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	abstract	A method to perform signal validation for either reactor fixed incore detectors and/or core exit thermocouples to enhance core monitoring systems. The method uses a combination of both measured sensor signals and expected signal responses to develop a ratio of measured to expected signals. The ratios are evaluated by determining the expected ratios for each detector based on the behavior of the remaining collection of detectors, taking into account the geometry/location of the other detectors. The method also provides for automatic removal of invalid detectors from the core power distribution determination if sufficient detectors remain on line to adequately characterize the core's power distribution.
	abstract	A fuel assembly for a nuclear water reactor having an upstream end, a downstream end, and a flow interspace between the upstream and downstream ends. Fuel rods are provided in the flow interspace between the upstream and downstream ends. The flow interspace permits a flow of coolant through the fuel assembly along a flow direction from the upstream end to the downstream end. A filter device is provided to catch debris particles in the flow of coolant. The filter device has a first filter zone for a major part of the flow of coolant, and a second filter zone for a minor part of the flow of coolant. The first filter zone has a first filtering efficiency and the second filter zone has a second filtering efficiency. The second filtering efficiency is higher than the first filtering efficiency.
047479957	summary	BACKGROUND OF THE INVENTION In previous art the previous application, Ser. No. 692,849 to A. H. Krieg, filed Mar. 11, 1985, a control rod crushing device was introduced. This device was developed in order to reduce the volume of spent radioactive BWR control rods. In the process of development, it was determined that the velocity limiter end of the control rod was too substantial to crush and a method had to be developed to remove this portion of the control rod without polluting the containment pool. For this reason we developed the velocity limiter shear for BWR control rods. SUMMARY OF THE INVENTION The object of this invention is to provide a machine that can operate underwater in hazardous environment via remote control, shear off the velocity limiter from the BWR control rod and carry out this function without the release of any of the materials contained in the fins of the control rod. Furthermore, the invention is foreseen with a method for positioning and aligning the control rod in a simple and practical manner. This second portion of the invention is called an alignment system. A third function of the invention is that 2 fins of the control rod are sheared simultaneously so that side pressure or the inherent intrinsic slippage, is met with a counter action to a one sided shearing function, and is by equal pressure from both sides contained. Yet another function of this invention is the rotation of the control rod so as to allow the second set of fins to be sheared. Referring now to the drawings in which like numeral refer to like parts: In FIG. 1, we see a side view representative of the apparatus where #13 is the handle attached to #11 control rod with #12 "D" shaped holes located near the bottom end of the #11 control rod where the #15 cylindrical protrusion and #17 wheel like protrusions are. The #18 shearing heads are fed into cutting position by #19 retraction and feeding cylinders and are activated by #20 shear activating cylinders. After the first shearing operation is completed, the #18 shearing heads are retracted and the #14 rotary table cylinder turns the #16 rotary table which rotates the #11 control rod 90.degree. for the next shearing operation. In FIG. 2, we see a top view representative of the apparatus where the #11 control rod is positioned in the shearing apparatus and #18 shearing heads are being activated by #20 shear activating cylinders. The #19 retraction and feeding cylinders hold the #18 shearing heads in place while the shearing function is performed. A further function is the ability to retract the shearing heads from their forward cutting and working position, so as to allow the control rod to be rotated.
053696751	abstract	Electrically controlled load activating mechanisms that can be used inside the containment vessel of a nuclear reactor in conjunction with bellows-loaded DCB crack growth sensors installed inside the reactor pressure vessel or piping of a nuclear reactor. One mechanism is a liquid-filled, double-bellows master/slave arrangement connected by a capillary tube to transmit the loading provided by a linear motion device. Another mechanism uses a heat-resistant gas bottle that can be heated in a furnace to increase the gas pressure to expand the bellows of the DCB sensor. A third mechanism uses a pump or compressor to provide the necessary expansion force. The loading is controlled via electrical connections that do not require special pressure boundary penetrations of the containment vessel.
	description	This application is a Continuation of U.S. application Ser. No. 10/232,853 filed on Aug. 28, 2002, now U.S. Pat. No. 6,898,779 which is incorporated herein by reference. This application is related to the following co-pending, commonly assigned U.S. patent application: “Method and Apparatus for Forming a Pattern on a Semiconductor Surface,” U.S. application Ser. No. 10/229,330, filed Aug. 27, 2002; of which the disclosure is herein incorporated by reference in its entirety. The invention relates to semiconductor devices and device fabrication. Specifically, the invention relates to designing patterns of elements on a surface of a semiconductor wafer. In fabricating integrated circuits (IC's) on a surface of a semiconductor wafer, a number of electronic devices are formed on or within the surface of the wafer. Any of a number of electronic devices may be formed on the surface of the wafer, such as transistors, capacitors, diodes, etc. Electronic devices include active areas such as a body region of a transistor, or a source/drain region of a transistor. After the individual electronic devices are formed on the surface of the wafer, selected electronic devices must be interconnected to form the IC. One typical approach to interconnecting electronic devices is to deposit metal interconnect traces on the surface of the wafer, usually on top of the electronic devices. The interconnect traces typically take the form of trace lines, with a line width that is generally the same along a length of the trace line. The traces connect at least one active region of a first electronic device with an active region of a second electronic device, allowing the devices to communicate with one another, and perform complex operations such as processing or storing information. Trace lines, however, create a rough surface on the wafer with the trace lines as high points, and the spaces between traces as low points. In many IC designs, there is a need to form a substantially planar surface on the wafer over the trace lines. For example, most IC designs stack multiple layers of electronic devices on top of each other. Layers of trace lines interconnect electronic devices on each respective layer, frequently with vias connecting between layers. The surface of each trace line layer must be substantially planar, and electrically isolated in order to form subsequent layers of electronic devices. One approach in the industry has been to deposit an inter layer dielectric (ILD) over the trace lines. The ILD electrically isolates the trace line layer, and it can be planarized to form the necessary surface for subsequent layers. Current devices and methods design a pattern of trace lines that merely considers electrical connection of electronic devices. The effects of the chosen pattern on subsequent wafer fabrication steps such as deposition of an ILD layer is not currently considered. Current devices and methods require multiple steps and multiple layers for effective isolation and planarization of the trace line layer. Current devices and methods also produce significant variation in ILD thickness. Current devices and methods are thus more costly due to additional fabrication steps, and less reliable due to resulting thickness variations. Thick ILD layer regions are undesirable, because formation of subsequent vias is difficult due to the extra distance that the vias must tunnel through. Variation in ILD thickness is undesirable because, among other problems, subsequent via etching must either under etch thick regions, or over etch thin regions of the ILD. What is needed is a method of forming a pattern of elements, such as trace lines, on a surface of a semiconductor wafer that results in fewer subsequent fabrication steps. What is also needed is a method of forming a pattern of elements, such as trace lines, that allows a thinner, more planar deposition of an ILD layer with a more uniform thickness. A method of forming a pattern of elements on a semiconductor wafer is shown. In one embodiment, the method includes choosing a first location of a number of edges of a number of conductive elements. The location of the number of edges define at least one space between elements. The method further includes selecting spaces that possess space dimensions within a range. The range includes a minimum dimension and a maximum dimension. The method further includes choosing a desired space dimension based on characteristics of the pattern of elements adjacent to selected spaces, and modifying the first location of at least a portion of one of the number of edges to a second location. In the second location, the space dimension is substantially the desired space dimension. A machine-readable medium with instructions stored thereon is also shown. In one embodiment, the instructions, when executed, are operable to cause selection of a first location of a number of edges of a number of conductive elements. The location of the number of edges define at least one space between elements. The instructions further cause selection of TODO spaces that possess space dimensions within a range. The range includes a minimum dimension and a maximum dimension. The instructions further cause selection of a desired space dimension. The desired space dimension is based on characteristics of the pattern of elements adjacent to selected spaces. The instructions further cause modification of the first location of at least a portion of one of the number of edges adjacent to one of the TODO spaces to a second location. In the second location, the space dimension is modified to the desired space dimension. These and other embodiments, aspects, advantages, and features of the present invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art by reference to the following description of the invention and referenced drawings or by practice of the invention. The aspects, advantages, and features of the invention are realized and attained by means of the instrumentalities, procedures, and combinations particularly pointed out in the appended claims. In the following detailed description of the invention, reference is made to the accompanying drawings which form a part hereof, and in which is shown, by way of illustration, specific embodiments in which the invention may be practiced. In the drawings, like numerals describe substantially similar components throughout the several views. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. Other embodiments may be utilized and structural, logical, and electrical changes may be made without departing from the scope of the present invention. The terms wafer and substrate used in the following description include any structure having an exposed surface with which to form the integrated circuit (IC) structure of the invention. The term substrate is understood to include semiconductor wafers. The term substrate is also used to refer to semiconductor structures during processing, and may include other layers, such as silicon-on-insulator (SOI), etc. that have been fabricated thereupon. Both wafer and substrate include doped and undoped semiconductors, epitaxial semiconductor layers supported by a base semiconductor or insulator, as well as other semiconductor structures well known to one skilled in the art. The term conductor is understood to include semiconductors, and the term insulator or dielectric is defined to include any material that is less electrically conductive than the materials referred to as conductors. The term “horizontal” as used in this application is defined as a plane parallel to the conventional plane or surface of a wafer or substrate, regardless of the orientation of the wafer or substrate. The term “vertical” refers to a direction perpendicular to the horizontal as defined above. Prepositions, such as “on”, “side” (as in “sidewall”), “higher”, “lower”, “over” and “under” are defined with respect to the conventional plane or surface being on the top surface of the wafer or substrate, regardless of the orientation of the wafer or substrate. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims, along with the full scope of equivalents to which such claims are entitled. FIG. 1A shows a first planned surface 100 of a semiconductor wafer. In one embodiment, the first planned surface 100 is not in a final state. In one embodiment, the first planned surface has not been put into a permanent physical form such as in a reticle for photolithographic processing, or a pattern of physical trace lines. In one embodiment, the first planned surface 100 is defined by data stored on a machine readable media, such as a computer memory, a hard disk drive, a floppy disk, optical storage, other storage media, etc. The first planned surface 100 includes a number of conductive elements 102, each defined by a number of edges 104. In one embodiment, the conductive elements include a metal. In one embodiment, a single element metal, such as aluminum is used. In one embodiment, a metal is included in an alloy. Other conductive materials are also possible, such as semiconductors. In one embodiment, the conductive elements 102 include trace lines. In one embodiment, the conductive elements 102 are adapted to interconnect at least a pair of active regions, such as source/drain regions of transistors. In one embodiment, the conductive elements 102 of the first planned surface 100 are located based primarily on electrical considerations of interconnecting a number of active regions. In FIG. 1A, the edges 104 of the conductive elements 102 define a number of spaces 106 between elements. Along a chosen direction, such as a Y-direction, a dimension of the spaces 106 can be measured. FIG. 1B shows a number of elements 110 which are shaped in rectangles for ease of illustration. One embodiment of the invention includes a set of dimensional rules that apply to elements such as the number of elements 110. The following description of dimensional rules between elements 110 is applicable to the conductive elements 102 shown in FIG. 1A. In FIG. 1B, all dimensions are measured along direction 111. One of ordinary skill in the art, with the benefit of the present disclosure, will recognize that although the single direction 111 is shown in FIG. 1B, the rules described herein regarding element and space dimensions are applicable to any chosen measurement direction in a pattern of elements. Element 130 is shown with a threshold dimension 116. Element 140 is shown with a second dimension 112 that is greater than the threshold dimension 116. Element 130 is shown separated from element 140 by a desired large element gap 114. In one embodiment, the desired large element gap is defined as the minimum spacing dimension that can be located adjacent to an element with an element dimension larger than the threshold dimension 116. As shown, element 140 includes the second dimension 112 that is larger than the threshold dimension 116, therefore the minimum separation between elements 140 and 130 is the desired large element gap 114. Element 150 is shown with a third dimension 119 that is smaller that the threshold dimension 116. In one embodiment, the third dimension 119 is defined as a minimum lithographic line width. Element 150 is shown directly adjacent to a first space 152 and a second space 154. The first space 152 is shown with a minimum space dimension 118. In one embodiment, the first space 152 and the second space 154 have substantially the same minimum space dimension 118. An SLS dimension 120 is defined as being substantially equal to a space+line+space (SLS) where the line is the minimum lithographic line dimension, and the two adjacent spaces are both equal to the minimum lithographic space as formed when adjacent to a minimum lithographic line dimension. It should be noted that the minimum space dimension 118 is smaller than the desired large element gap 114. This is allowed due to lithographic techniques that allow thin spaces, but only when they are adjacent to elements thinner than a certain dimension. In one embodiment, elements that are thin enough to be located next to a space smaller than desired large element gap 114 must have element dimensions in a limited range. In one embodiment, the limited range includes the minimum lithographic line width 119 and the limited range can be as large as the threshold dimension 116. A third space 156 is further shown in FIG. 1B with a dimension 122 that is greater than the SLS dimension 120. In one embodiment, a FLOAT area is defined as an area with dimensions that are large enough to allow insertion of at least one element within the FLOAT area while complying with the above described dimensional rules. Additional elements within a FLOAT area, in one embodiment, are referred to a floating elements because they are not coupled to any active areas of electronic devices. The additional elements are electrically “floating” on top of an isolated substrate region. In one embodiment, floating elements are included to improve subsequent ILD layer deposition kinetics as discussed below. In FIG. 1B, the dimension 122 of the third space 156 allows insertion of an additional element, and thus qualifies as a FLOAT space dimension. It should be noted that the smallest dimension of a FLOAT area dimension depends on the dimensions of the elements that surround the area. The minimum lithographic line width 119 remains the same in one embodiment for all configurations. However, according to the dimensional rules above, if surrounding elements include one or more “large” elements with dimensions greater than the threshold dimension 116, then the desired large element gap 114 is needed adjacent to the floating element. Likewise, if surrounding elements include one or more elements with dimensions less than or equal to the threshold dimension 116, then a space as small as the minimum space dimension 118 can be used. In one embodiment, a FLOAT area includes both desired large element gap 114 dimensions surrounding a floating element and minimum space dimensions 118 surrounding the floating element. A TODO area is defined as a space between elements with at least one dimension that is larger than desired large element gap 114 where the space is also not large enough to insert a floating element under the above dimensional rules. TODO areas are located in a pattern of elements and modified as described below. Dimensional rules such as the rules described above are driven by subsequent wafer processing steps in one embodiment. As discussed above, it is often desirable to form subsequent structure such as an inter layer dielectric (ILD) between elements on a wafer, such as conductive elements 102 from FIG. 1A. In many designs, the ILD must be substantially planar, and a thin, consistent ILD layer is more desirable due to subsequent addition of conductive vias through the ILD. It has been discovered that the deposition process of an ILD layer using processes such as spin-on-glass or CVD is not isotropic. Spaces of different sizes and dimensions fill at different rates. Anisotropic fill rates are minimized by controlling space dimensions, which leads to a more consistent, planar ILD surface, and a more simple fabrication process for deposition and planarization of the ILD surface. Dimensional rules, in one embodiment, are chosen based on these ILD fill dynamics considerations. Dimensions such as the desired large element gap 114, the minimum space dimension 118, etc. provide an ILD deposition process requiring fewer steps, resulting in a thinner, more planar, more consistent ILD layer that is more reliable. Likewise, in one embodiment, the addition of floating elements is driven by the desire for spaces between elements in a pattern that are more easily filled and planarized in a subsequent ILD process. In one embodiment, a pattern of elements utilizing dimensional rules as described above can be filled and planarized in a single processing operation. FIG. 1C shows the spaces 106 of FIG. 1A further divided into categories based on the dimensions of the spaces 106 and the dimensional rules above. The first planned surface 100, in FIG. 1C, shows a FLOAT region 160. The first planned surface 100 in FIG. 1C also includes a number of TODO regions 170. In one embodiment, the dimensions of elements and spaces at various locations in the first planned surface 100 are measured substantially along X and Y directions as indicated in the Figures. One skilled in the art, having the benefit of the present disclosure, will recognize that a dimension of the spaces 106 can be alternatively measured on any of a wide range of directions other than X and Y directions. The following descriptions and Figures describe methods that are used to convert the first planned surface 100 to a surface with spaces that conform to dimensional rules as described above, and as a result are more easily filled by an ILD fabrication process. In one embodiment, edges of FLOAT regions 160 are not modified. In one embodiment, the TODO regions are modified based on methods that are described below. Edges or portions of edges of conductive elements adjacent to the TODO region are identified and ranked based on a set of movement rules. The edges or portions of edges are then moved according to the movement rules with the highest ranking edges moving first. In this way, the spaces between elements are substantially brought within the space dimensional rules described above. It should again be noted that location and movement of edges and spaces is performed in a virtual environment, such as in a computer. In one embodiment, the final planned pattern of elements is in a state that is more effective for subsequent processing steps such as ILD deposition. In addition to bringing the pattern of elements into compliance with dimensional rules, in one embodiment the movement rules are designed to avoid dead end patterns. If edges are not moved in a certain order, it is possible to create dead end patterns that do not conform to the space dimensional rules as described above, yet at the same time, movement rules do not allow movement of edges to correct the dead end pattern. One example of a dead end pattern includes a “pinwheel” pattern. FIG. 1D shows an example of a pinwheel pattern 180. Because all adjacent elements 182 include dimensions greater that the threshold dimension 116, a desired large element gap 114 is needed between the elements. As indicated in FIG. 1D, the TODO region 184 is a square with dimension 186 measuring larger than a desired large element gap, but smaller than a FLOAT area under the given conditions (two times a desired large element gap plus a minimum lithographic dimension). This region is a dead end because the space is larger than desired large element gap, floating elements cannot be added and no edges can be moved into the TODO region under the dimensional rules because at least a desired large element gap 114 is needed between any moved edges. In one embodiment, the movement rules avoid dead end patterns by using rules such as edge rankings and edge movement distance rules. In one embodiment, movement rules include subdividing the TODO regions, or fracturing the TODO regions into smaller regions before moving any edges. FIG. 2A shows a planned surface 200 with a number of conductive elements 210 and a number of TODO regions 220. A selected TODO region 220 is shown fractured along the X-direction into a number of rectangles by defining a number of sub-edges 222 of the TODO region that are normal to the X-direction. In one embodiment, edges of the conductive elements 210 adjacent to newly formed sub-regions of the TODO region 220, and normal to the X-direction are moved in the X-direction. Similarly, in FIG. 2B, a TODO region 220 is shown fractured along the Y-direction into a number of rectangles by defining a number of sub-edges 224 of the TODO region that are normal to the Y-direction. In one embodiment, edges of the conductive elements 210 adjacent to newly formed sub-regions of the TODO region 220, and normal to the Y-direction are moved in the Y-direction. One advantage of fracturing the TODO regions into sub-regions is that the sub-regions are geometrically more simple than the parent TODO region. In one embodiment, computations and evaluations involving the sub-regions are less complex. Although rectangles are shown in FIGS. 2A and 2B, other geometric shapes are within the scope of the present disclosure. In one embodiment, fracturing of TODO regions is performed along one direction at a time. In one embodiment, fracturing and moving edges of TODO regions is performed a number of times. In one embodiment, fracturing and moving of edges is iteratively performed in the X-direction and the Y-direction until the TODO regions are substantially in compliance with the dimensional rules described above. In one embodiment, movement rules include a rule where edges of conductive elements are allowed to move only within a sub-element that is bounded by the edge to be moved. In one embodiment, movement rules include a rule where if multiple co-linear edges of a conductive element are adjacent to a sub-element of a TODO region, the multiple co-linear edges are moved together by the same amount. FIGS. 3A-3C illustrate additional movement rules based on edge classification. FIG. 3A shows a planned surface 300 for a semiconductor wafer. The planned surface 300 includes a number of conductive elements 310 with a number of spaces defined between edges of the conductive elements 310. A number of TODO regions 320 are also shown. The TODO regions 320 form boundaries 322 with selected conductive elements 310 along various edges of the conductive elements 310 or along portions of edges of the conductive elements 310. The edges of conductive elements 310, in one embodiment, are classified according to certain characteristics of the boundaries 322. FIG. 3A shows a number of inside edges 330 that are highlighted by a bold line and inside edge endpoints 332. In one embodiment, the inside edges 330 are defined as edges of the conductive elements 310, and not edges of the TODO regions 320. In one embodiment, the inside edges 330 are each further defined as sharing a continuous common boundary 322 with a TODO region. In one embodiment, while evaluating a classification of an edge of a conductive element 310, the entire edge between corners must be considered. In one embodiment, the inside edges are each further defined as an edge of a conductive element 310 where both inside edge endpoints 332 include outside corners of the conductive elements 310. Outside corners, in one embodiment, are defined as corners with conductive element angles 334 that are less than 180 degrees as measured across the conductive element. In one embodiment, the conductive element angles 334 are approximately 90 degrees. FIG. 3B shows the planned surface 300 with the conductive elements 310 and the TODO regions 320. FIG. 3B highlights a number of corner edge groups 340. The corner edge groups 340 include a number of linked individual corner edges 342. The individual corner edges are each bounded by corner edge endpoints 344. Similar to inside edges discussed in FIG. 3A, in one embodiment, the corner edges 340 are defined as edges of the conductive elements 310, and not edges of the TODO regions 320. In one embodiment, the corner edges 340 are each further defined as sharing a continuous common boundary 322 with a TODO region. In one embodiment, while evaluating a classification of an edge of a conductive element 310, the entire edge between corners must be considered. In one embodiment, the corner edges are each further defined as an edge of a conductive element 310 where at least one corner edge endpoint 344 includes an inside corner of a conductive element 310. Inside corners, in one embodiment, are defined as corners with conductive element angles 346 that are greater than 180 degrees as measured across the conductive element. In one embodiment, the conductive element angles 346 of inside corners are approximately 270 degrees. FIG. 3C shows the planned surface 300 with the conductive elements 310 and the TODO regions 320. FIG. 3C highlights a number of straddling edges 350 with straddling edge endpoints 352. Similar to inside edges and corner edges discussed in FIGS. 3A and 3B, in one embodiment, the straddling edges 350 are defined as edges of the conductive elements 310, and not edges of the TODO regions 320. In one embodiment, the straddling edges 350 are each further defined as sharing a common boundary 322 with a TODO region, as well as sharing an external boundary 324 with a space region 360 that is not a TODO region. In one embodiment, while evaluating a classification of an edge of a conductive element 310, the entire edge between corners must be considered. In one embodiment, corners at the straddling edge endpoints 352 may be either inside corners or outside corners as defined above. In one embodiment, the classified edges are moved in ranking order. One ranking moves the inside edges first, the corner edges second, and the straddling edges third. In one embodiment, in a situation including both inside edges and corner edges, the edges are both ranked as corner edges. In one embodiment, in a situation including inside edges, corner edges, and straddling edges, the edges are all ranked as straddling edges. Movement rules that include ranking of edges as described above avoid dead end structures, such as pinwheels. In one embodiment, additional rules as described below are included for moving notches and moving structures of long parallel edges. FIG. 4 shows a planned surface 400 with a number of conductive elements 410 and a number of TODO regions 420. An edge 422 is identified for a move, and is moved along direction 426 to a second location 424. In one embodiment, the edge 422 is classified as a notch. In one embodiment, a notch includes a corner edge that includes an outside corner on both corner edge endpoints. In one embodiment, notches are moved with the highest priority. FIG. 5 shows a planned surface 500 with a number of conductive elements 510 and a number of TODO regions 520. An edge 521 is identified as a long parallel edge with edge 519. In one embodiment, a portion of long parallel edges 521 and 519 are each moved along arrows 525 and 523 to new locations 524 and 522 respectively. In one embodiment the movement of long parallel edges is performed symmetrically as shown in FIG. 5. Symmetrical movement of long parallel edges is desirable because signal integrity is maintained in the circuit. In one embodiment, long parallel edges are moved with the same priority as notches. As shown in FIG. 6A, one embodiment moves and entire edge of an element at one time. FIG. 6A shows an initial edge location 610 as a dashed line. The initial edge location 610 is moved in the direction 612 to a second location 614. FIG. 6B shows one embodiment where a portion of an edge 620 is moved. Edge 620 is sub-divided into a first portion 622 and a second portion 624. The first portion 622, shown as a dashed line, is moved along direction 626 to a second location 628. The second portion 624 is not moved in this embodiment. FIG. 6C shows a further embodiment where an edge 630 is sub-divided into a number of portions. A first portion 632, a second portion 634, a third portion 636, and a fourth portion 638. The first portion 632 is moved along direction 644 to a second location 646. Likewise the third portion 636 is moved along direction 640 to a second location 642. The second portion 634 and the fourth portion 638 remain in their original locations. One of ordinary skill in the art, with the benefit of the present disclosure, will recognize that other similar combinations of edge sub-division, and moves are possible. FIGS. 6A-6C illustrate some examples of edge, and sub-edge movement. The invention is not so limited to these examples. FIG. 7 shows a flow diagram of one embodiment utilizing dimensional rules and movement rules as described above. In FIG. 7, all TODO regions are sub-divided into rectangles before edge modification takes place. Although rectangles are used in one embodiment as sub-divided geometric shapes, other sub element shapes such as triangles parallelograms, etc, are also acceptable sub element shapes. The flow diagram of FIG. 7 utilizes spaces of a desired gap. In one embodiment, a desired gap includes multiple gap spacing. In one embodiment, dimensional rules as described above determine a desired gap. One possible desired gap includes a desired large element gap that is sized based on “large” adjacent conductive elements. Another possible desired gap includes a minimum lithographic gap that is sized smaller that desired large element gap only when permitted by the dimensional rules. One example allowing a minimum lithographic gap smaller than a desired large element gap includes a condition where adjacent conductive elements are sized less than or equal to a threshold dimension. FIG. 8 shows a flow diagram of one embodiment that looks beyond adjacent edges of conductive elements of a TODO regions to help determine what a desired gap dimension is. In one embodiment, conductive elements adjacent to a TODO region are checked to see if they are “large” elements that would require a desired large element gap adjacent to them. In one embodiment, conductive elements adjacent to a TODO region are checked to see if they are sized smaller than a threshold dimension that in turn allows a minimum lithographic gap adjacent to the conductive element. In one embodiment, a test region is defined as a region with dimensions in all directions sized larger than the TODO region by an amount equal to the threshold dimension plus a small amount. If a portion of the test region intersects an adjacent portion of a conductive region, then the adjacent portion of the conductive region is labeled as being larger than the threshold dimension. Conversely, if a portion of the test region intersects a space, then the adjacent portion of the conductive region is labeled as being less than or equal to the threshold dimension. While checking a test region as described above is one possible method of characterizing adjacent conductive elements, the present invention is not so limited. Other methods that determine a variable desired gap spacing based on a size or dimensions of adjacent conductive elements are also within the scope of the present invention. FIG. 9 provides a brief, general description of a suitable computing environment in which the above embodiments may be implemented. Embodiments of the invention will hereinafter be described in the general context of computer-executable program modules containing instructions executed by a personal computer (PC). Program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Those skilled in the art will appreciate that the invention may be practiced with other computer-system configurations, including hand-held devices, multiprocessor systems, microprocessor-based programmable consumer electronics, network PCs, minicomputers, mainframe computers, and the like which have multimedia capabilities. The invention may also be practiced in distributed computing environments where tasks are performed by remote processing devices linked through a communications network. In a distributed computing environment, program modules may be located in both local and remote memory storage devices. FIG. 9 shows a general-purpose computing device in the form of a conventional personal computer 20, which includes processing unit 21, system memory 22, and system bus 23 that couples the system memory and other system components to processing unit 21. System bus 23 may be any of several types, including a memory bus or memory controller, a peripheral bus, and a local bus, and may use any of a variety of bus structures. System memory 22 includes read-only memory (ROM) 24 and random-access memory (RAM) 25. A basic input/output system (BIOS) 26, stored in ROM 24, contains the basic routines that transfer information between components of personal computer 20. BIOS 26 also contains start-up routines for the system. Personal computer 20 further includes hard disk drive 27 for reading from and writing to a hard disk (not shown), magnetic disk drive 28 for reading from and writing to a removable magnetic disk 29, and optical disk drive 30 for reading from and writing to a removable optical disk 31 such as a CD-ROM or other optical medium. Hard disk drive 27, magnetic disk drive 28, and optical disk drive 30 are connected to system bus 23 by a hard-disk drive interface 32, a magnetic-disk drive interface 33, and an optical-drive interface 34, respectively. The drives and their associated computer-readable media provide nonvolatile storage of computer-readable instructions, data structures, program modules and other data for personal computer 20. Although the exemplary environment described herein employs a hard disk, a removable magnetic disk 29 and a removable optical disk 31, those skilled in the art will appreciate that other types of computer-readable media which can store data accessible by a computer may also be used in the exemplary operating environment. Such media may include magnetic cassettes, flash-memory cards, digital versatile disks, Bernoulli cartridges, RAMs, ROMs, and the like. Program modules may be stored on the hard disk, magnetic disk 29, optical disk 31, ROM 24 and RAM 25. Program modules may include operating system 35, one or more application programs 36, other program modules 37, and program data 38. A user may enter commands and information into personal computer 20 through input devices such as a keyboard 40 and a pointing device 42. Other input devices (not shown) may include a microphone, joystick, game pad, satellite dish, scanner, or the like. These and other input devices are often connected to the processing unit 21 through a serial-port interface 46 coupled to system bus 23; but they may be connected through other interfaces not shown in FIG. 9, such as a parallel port, a game port, or a universal serial bus (USB). A monitor 47 or other display device also connects to system bus 23 via an interface such as a video adapter 48. In addition to the monitor, personal computers typically include other peripheral output devices (not shown) such as speakers and printers. In one embodiment, one or more speakers 57 or other audio output transducers are driven by sound adapter 56 connected to system bus 23. Personal computer 20 may operate in a networked environment using logical connections to one or more remote computers such as remote computer 49. Remote computer 49 may be another personal computer, a server, a router, a network PC, a peer device, or other common network node. It typically includes many or all of the components described above in connection with personal computer 20; however, only a storage device 50 is illustrated in FIG. 9. The logical connections depicted in FIG. 9 include local-area network (LAN) 51 and a wide-area network (WAN) 52. Such networking environments are commonplace in offices, enterprise-wide computer networks, intranets and the Internet. When placed in a LAN networking environment, PC 20 connects to local network 51 through a network interface or adapter 53. When used in a WAN networking environment such as the Internet, PC 20 typically includes modem 54 or other means for establishing communications over network 52. Modem 54 may be internal or external to PC 20, and connects to system bus 23 via serial-port interface 46. In a networked environment, program modules, such as those comprising Microsoft® Word which are depicted as residing within 20 or portions thereof may be stored in remote storage device 50. Of course, the network connections shown are illustrative, and other means of establishing a communications link between the computers may be substituted. Software may be designed using many different methods, including object oriented programming methods. C++ and Java are two examples of common object oriented computer programming languages that provide functionality associated with object oriented programming. Object oriented programming methods provide a means to encapsulate data members (variables) and member functions (methods) that operate on that data into a single entity called a class. Object oriented programming methods also provide a means to create new classes based on existing classes. An object is an instance of a class. The data members of an object are attributes that are stored inside the computer memory, and the methods are executable computer code that act upon this data, along with potentially providing other services. The notion of an object is exploited in the present invention in that certain aspects of the invention are implemented as objects in one embodiment. An interface is a group of related functions that are organized into a named unit. Each interface may be uniquely identified by some identifier. Interfaces have no instantiation, that is, an interface is a definition only without the executable code needed to implement the methods which are specified by the interface. An object may support an interface by providing executable code for the methods specified by the interface. The executable code supplied by the object must comply with the definitions specified by the interface. The object may also provide additional methods. Those skilled in the art will recognize that interfaces are not limited to use in or by an object oriented programming environment. Computers and computer-executable program modules, etc are used in one embodiment of the invention to generate patterns as described above for use on a semiconductor surface. The detailed description of the method and associated devices above is used, in one embodiment, to create a reticle for lithography of a semiconductor wafer surface. In one embodiment, a pattern on the reticle is first generated using computer software to interconnect a number of active areas on the wafer. The first pattern is not physically formed, and it's pattern is stored as data for modification as described above. The first pattern is then modified according to the teachings above to create a pattern that conforms to dimensional rules as described above with desired spaces between elements. In further embodiments, a semiconductor wafer is formed using the reticle generated by the method of the software described above. Elements such as metal trace lines are formed on the wafer in one embodiment, although the invention is not limited to metal trace lines. Layers of elements such as trace lines can be better covered with an ILD in a simplified deposition process due to the teachings of pattern formation as described above. An ILD layer can also be deposited over a layer of elements in a planar surface that is thinner and more consistent in thickness than was possible using prior techniques. An ILD layer that is thinner and more consistent than prior ILD layers provides benefits such as the ability to form more reliable vias. Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that any arrangement which is calculated to achieve the same purpose may be substituted for the specific embodiment shown. This application is intended to cover any adaptations or variations of the present invention. It is to be understood that the above description is intended to be illustrative, and not restrictive. Combinations of the above embodiments, and other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the invention includes any other applications in which the above structures and fabrication methods are used. The scope of the invention should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.
	abstract	A collimator includes an x-ray blocking surface including one or more generally flat plates defining an aperture edge. The aperture edge includes a first end portion including a first end of the aperture edge, a second end portion including a second end of the aperture edge, and a central portion including a center of the aperture edge. The first end portion of the aperture edge corresponds to a first end portion of a detector, the second end portion of the aperture edge corresponds to a second end portion of the detector, and the central portion of the aperture edge corresponds to a central portion of the detector. A profile of the aperture edge is discontinuous at a point between the first end of the aperture edge and the center of the aperture edge.
059360070	summary	BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The invention relates to copolycarbonates based on diphenols and one or more stabilisers, stabilised against the discolouring effect of .gamma.-radiation. SUMMARY OF THE INVENTION The invention provides polycarbonate moulding compositions containing a) 97.5 wt. % to 99.9 wt. % of a polycarbonate or copolycarbonate and b) 0.1 wt. % to 2.5 wt. % of a .gamma.-radiation stabiliser of the general formula (I), each with reference to 100 wt. % of a)+b), EQU R.sub.1 --X--(CHR.sub.4).sub.n --Y--R.sub.2 (I) in which R.sub.1, R.sub.2 and R.sub.4 represent C.sub.1 -C.sub.36 optionally branched alkyl groups, preferably C.sub.1 -C.sub.12 optionally branched alkyl groups or C.sub.16 -C.sub.24 optionally branched alkyl groups, C.sub.7 -C.sub.18 optionally branched and/or substituted alkylaryl or arylalkyl groups or C.sub.6 -C.sub.18, preferably C.sub.6, optionally substituted aryl groups and R.sub.4 may also represent H, and in which "n" is a number between 1 and 8, preferably 1, and if R.sub.1 =R.sub.2 =benzyl and Y is a single bond, may also be zero, and wherein X and Y, independently of each other, are ##STR1## and Y may also represent --S--where R.sub.3 is defined in the same way as R.sub.1, wherein R.sub.3 is preferably methyl, benzyl or phenyl, or in which X or Y is a single chemical bond; groups R.sub.1 and R.sub.2 which are part of a 4 to 12-membered, preferably 5 or 6-membered, optionally heterocyclic ring system, via groups X and Y respectively, wherein in this case R.sub.1 or R.sub.2 may be a single bond, are also suitable. Preferred compounds (I) are those in which X and/or Y represent ##STR2## and those in which X or Y represent a single bond and those in which Y=--S--. Particularly preferred compounds (I) are those in which X is ##STR3## and Y is ##STR4## or a single bond. In a specific embodiment of compounds (I), R.sub.1 =R.sub.2 =benzyl, Y is a single bond and n=0. As a further stabiliser c), 0.05 wt. % to 5 wt. %, preferably 0.1 wt. % to 1.5 wt. %, of optionally terminally capped and/or branched polypropylene glycol with an average molecular weight of 200 to 200,000, preferably 800 to 4,000, may be contained in the polycarbonate moulding compositions according to the invention, wherein the percentages by weight of c) are each with reference to 100 wt. % of a)+b). DESCRIPTION OF THE PRIOR ART The prior art relating to stabilisation against .gamma.-radiation comprises incorporating oligomeric polypropylene glycols (EP 376 289), oligomeric, brominated bisphenol A polycarbonates (EP 114 973), blends of polycarbonate and polyesters based on terephthalic acid and cyclohexanedimethanol (EP 152 012), organic disulphides (U.S. Pat. No. 5,382,605 (Mo 3788)) or organic monosulphides (EP-611 797 (Mo 3913+Mo 3960)), each optionally combined with oligomeric polypropylene glycols, into the polycarbonate. The disadvantages associated with these stabilisers are, for instance, as follows: polypropylene glycol on its own provides inadequate stabilisation at high radiation doses, brominated systems are preferably not used because of the presence of a halogen, the use of polyester blends means that superheated steam sterilisation cannot be applied and in the case of a disulphide system there is a small processing window prior to decomposition. When using a monosulphide system in accordance with EP-0 611 797, on the other hand, as is also the case with a disulphide system, nuisance effects due to unpleasant odours cannot be excluded. There was therefore the object of developing an additive system which is stable under manufacturing and processing conditions, which produces superheated steam sterilisable moulded articles, in order to ensure universal applicability, does not utilise halogen-containing stabilisers and ensures adequate stabilisation when irradiated at 5 Mrad. The object was achieved by the use according to the invention of stabiliser (I). DESCRIPTION OF THE PREFERRED EMBODIMENTS Suitable diphenols for the preparation of polycarbonates to be used according to the invention are those of the general formula (II) EQU HO--Z--OH (II) with preferably 6 to 30 carbon atoms, either mononuclear or polynuclear diphenols, which may contain hetero-atoms and have substituents which are inert under the conditions of polycarbonate preparation and when exposed to thermal irradiation. Examples of these are hydroquinone, resorcinol, dihydroxydiphenyl, bis-(hydroxyphenyl)-alkanes, bis-(hydroxyphenyl)-cycloalkanes, bis-(hydroxyphenyl) sulphides, ethers, sulphoxides, sulphones and .alpha.,.alpha.-bis-(hydroxyphenyl)-diisopropylbenzenes as well as their ring-alkylated and ring-halogenated compounds. Suitable phenols are described, for example, in U.S. Pat. Nos. 3,028,365, 2,999,835, 3,062,781, 3,148,172 and 4,982,014, in DE-OS 1,570,703 and 2,063,050, and also in the monograph "H. Schnell, Chemistry and Physics of Polycarbonates, Interscience Publishers, New York, 1964". Preferred diphenols are 4,4'-dihydroxydiphenol, 2,2-bis-(4-hydroxyphenyl)-propane, 2,4-bis-(4-hydroxyphenyl)-2-methylbutane,1,1-bis-(4-hydroxyphenyl)-cyclohe xane, .alpha.,.alpha.-bis-(4-hydroxyphenyl)-p-diisopropylbenzene, .alpha.,.alpha.-bis-(4-hydroxyphenyl)-m-diisopropylbenzene, 2,2-bis-(3-methyl4-hydroxyphenyl)-propane, 2,2-bis-(3-chloro-4-hydroxyphenyl)-propane, bis-(3,5-dimethyl-4-hydroxyphenyl)-methane, 2,2-bis-(3,5-dimethyl-4-hydroxyphenyl)-propane, bis-(3,5-dimethyl-4-hydroxyphenyl) sulphone. 2,4-bis-(3,5-dimethyl-4-hydroxyphenyl)-2-methylbutane, 1,1-bis-(3,5-dimethyl-4-hydroxyphenyl)-cyclohexane, .alpha.,.alpha.-bis-(3,5-dimethyl-4-hydroxyphenyl)-p-diisopropylbenzene, 1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, 1,1-bis-(4-hydroxyphenyl)-3-methyIcyclohexane, 1,1-bis-(4-hydroxyphenyl)-3,3-dimethylcyclohexane, 1,1-bis-(4-hydroxyphenyl)-4-methylcyclohexane, 2,2bis-(3,5-dichloro-4-hydroxyphenyl)-propane, 2,2-bis-(3,5-dibromo-4-hydroxyphenyl)-propane, 1,1-bis-(4-hydroxyphenyl)-1 -phenylethane, 2,2-bis-(3,5-dimethyl-4-hydroxyphenyl)-2-phenylethane, 2,2-bis-(4-hydroxyphenyl)-2,2-diphenylethane, 9,9-bis-(4-hydroxyphenyl)-fluorene, 9,9-bis-(3,5-dimethyl-4-hydroxyphenyl)-fluorene. Particularly preferred diphenols are, for instance, 2,2-bis-(4-hydroxyphenyl)-propane, 2,2-bis-(3,5-dimethyl-4-hydroxyphenyl)-propane, 1,1 -bis-(4- hydroxyphenyl)-cyclohexane, 1,1-bis-(4-hydroxyphenyl)-1-phenylethane, 1,1-bis-(4- hydroxyphenyl)-3,3,5-trimethylcyclohexane, 1,1-bis-(4-hydroxyphenyl)-3-methylcyclohexane, 1,1-bis-(4-hydroxyphenyl)-4-methylcyclohexane, 9,9-bis-(3,5- dimethyl-4-hydroxyphenyl)-fluorene. In particular, 2,2-bis-(4-hydroxyphenyl)-propane, 1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane and 1,1-bis-(4-hydroxyphenyl)-1-phenylethane are preferred. Any mixture of the previously mentioned diphenols may also be used. With the objective of improving the flow behaviour, small amounts, preferably amounts between 0.05 and 2.0 mol-% (with reference to the moles of diphenols used), of trifunctional or more than trifunctional compounds, in particular those with three or more than three phenolic hydroxyl groups, may also be incorporated in a known manner during synthesis. Some of the compounds which may be used are, for instance, 1,3,5-tris-(4-hydroxyphenyl)-benzene, 1,3,5-tris-(4-(4-hydroxyphenyl-isopropyl)-phenyl)-benzene, 1,1,1-tris-(4-hydroxyphenyl)-ethane, 2,6-bis-(2-hydroxy-5'-methylbenzyl)-4-methylbenzene,2-(4-hydroxyphenyl)-2- (2,4-dihydroxyphenyl)-propane, esters of hexakis-(4-(4-hydroxyphenylisopropyl)-phenyl)-o-terephthalic acid, tetrakis-(4-hydroxyphenyl)-methane, 1,1-bis((4',4"-dihydroxytriphenyl)-methyl)-benzene, 3,3,-bis-(4-hydroxyphenyl)-2-oxo-2,3- dihydroindole, 3,3-bis-(4-hydroxy-3-methylphenyl)-2-oxo-2,3-dihydroindole, also suitable are the esters of the chlorocarbonic acids corresponding to these compounds and the acids, or preferably the acid chlorides, of more than 2-basic aliphatic or aromatic carboxylic acids, that is, for example, 2,4-dihydroxybenzoic acid or 2,4-dihydroxybenzoic dichloride, trimesic acid or trimesic trichloride, trimellitic acid or trimellitic trichloride, cyanuric trichloride, wherein these branching agents are initially introduced individually or as a mixture or may be added in portions during synthesis. Chain terminators which may be used in the synthesis include phenols, optionally substituted phenols, their chlorocarbonic acids, monocarboxylic acids, and their acid chlorides, preferably cumylphenol, phenol, tert.-butylphenol and i-octylphenol, optionally as mixtures. with conventional impurities and isomers, wherein the chain terminators may be initially introduced individually or as a mixture with the diphenols or may be added in portions during synthesis. The polycarbonates or polycarbonate mixtures to be used according to the invention may essentially be prepared by the following three known methods (see H. Schnell, "Chemistry and Physics of Polycarbonates", Polymer Review, vol. IX, pages 27 et seq., Interscience Publishers, New York, 1964): 1. By a solution process in dispersed phase, the so-called two-phase interfacial process". 2. By a solution process in homogeneous phase, also known as the "pyridine process". 3. By the melt transesterification process. Polycarbonates to be used according to the invention have average weight molecular weights M.sub.w (determined by measuring the relative viscosity in CH.sub.2 Cl.sub.2 at 25.degree. C. and at a concentration of 0.5 g in 100 ml of CH.sub.2 Cl.sub.2) between 10,000 and 80,000, preferably between 15,000 and 40,000. Conventional additives for thermoplastic polycarbonates such as stabilisers, that is e.g. thermal stabilisers such as, for example, organic phosphites, optionally in combination with monomeric or oligomeric epoxides, UV stabilisers, in particular those based on nitrogen-containing heterocyclic compounds such as triazoles, optical brighteners, flame retardants, in particular fluorine-containing compounds such as perfluorinated salts of organic acids, polyperfluoroethylene, salts of organic sulphonic acids and combinations of these, optionally other mould release agents, colorants, pigments, antistatic agents, fillers and reinforcing substances may be added in conventional amounts to the polycarbonate moulding compositions according to the invention, before, during or after processing. Preferred .gamma.-stabilisers of the formula (I) are in particular those of the formula (Ia) ##STR5## where R.sub.1 and R.sub.2, independently of each other, represent methyl, ethyl, i/n-propyl, i/n/t-butyl, i/n-pentyl, ethylhexyl, cyclopentyl, cyclohexyl, stearyl, palmityl, benzyl, phenyl, cresyl and myristyl, R.sub.4 represents H, CH.sub.3, benzyl and phenyl, Y represents --SO.sub.2 --, --S--, --SO--, --CO-- or a single bond and n=1 or 2. Particularly preferred are those compounds of the type (Ia) in which R.sub.1 and R.sub.2, independently of each other, represent methyl, phenyl or benzyl, R.sub.4 =H or CH.sub.3, Y represents --SO.sub.2 -- or --CO-- and n=1. Dibenzylsulphone is also particularly preferred, that is (Ia) where R.sub.1 =R.sub.2 =benzyl, Y=a single bond and n=zero. Stabilisers (I) and (Ia) are either known and described in the relevant works of reference such as Beilstein or Chemical Abstracts or can be synthesised by known methods of synthesis for, for example; 1,3-dicarbonyl compounds or sulphonic acids or sulphone compounds. The following references are given by way of example: Rompp: "Lexikon der Chemie", 9th ed., vol. 5, page 4384; Houben-Weyl: 9, pages 223 et seq., E11, pages 1132-1299; Kharash: "Organic Sulphur Compounds", vol. 1, pages 617 et seq.; Patai: "The Chemistry of Sulphones and Sulphoxides", pages 165 et seq., 232 et seq., 1988 J. Wiley & Sons; Winnacker-Kuchler: (3rd) 4, pages 166 et seq.; Beilstein vols. 6, I 6, II 6, in particular pages 305, 426, 456, 868, I 226, I 408, II 430, II 829 and II 854. Examples of stabilisers (I) are: a) 1,3-dicarbonyl compounds such as, for example, dimethyl, diethyl, di-i/n-propyl, di-i/n/t-butyl, di-i/n-pentyl, dicyclopentyl, dicyclohexyl, distearyl, dimyristyl, dipalmityl, dibenzyl, diphenyl esters of malonic acid and Meldrum's acid and its higher homologues based on other ketones. b) Methyl, ethyl, i/n-propyl, i/n/t-butyl, i/n-pentyl, ethylhexyl, cyclopentyl, cyclohexyl, stearyl, myristyl, palmityl, benzyl, phenyl esters or cresyl esters of optionally substituted acetic acid. c) Esters of the carboxylic acids mentioned under a), wherein one or both carboxyl groups are replaced by sulphonic acid groups. d) Sulphonic acid analogues of the acetates mentioned under b). e) The compounds mentioned under b) and d) after exchanging the carbonyl groups for SO.sub.2 groups. f) 1,3-diketones, such as e.g. 1,3-pentanedione. The stabilisers mentioned are used, individually or in any mixture, at concentrations of 0.1 wt. % to 2.5 wt. %, wherein they may be added in bulk, as a powder or a melt, or else as a solution before or during processing of the polycarbonate resin, or also in a subsequent compounding step. Dichloromethane and/or chlorobenzene, for example, may be used as a solvent for (I). It may be advantageous, if the moulding compositions also contain, in addition to the stabilisers mentioned, polypropylene glycols in amounts of 0.05 wt. % to 5 wt. %, preferably 0.1 wt. % to 1.5 wt. % of optionally terminally capped and/or branched polypropylene glycol with an average molecular weight of 200 to 200,000, preferably 800 to 4,000. This type of polypropylene glycol is known from the literature. In order to eliminate slight yellow coloration, which does occasionally occur, it may be beneficial under some circumstances to also provide the moulding compositions with the phosphorus-containing stabilisers which are conventionally used for polycarbonates. Polycarbonates according to the invention may be processed to give moulded articles by, for example, extruding the isolated polycarbonates to give a granular material in a known manner and processing this granular material, optionally after the addition of the additives mentioned above, by injection moulding in a known manner to produce a variety of articles. Polycarbonates according to the invention can be used as moulded articles in particular wherever it is known that polycarbonates have hitherto been used for this purpose, especially however in medical fields of application, that is, for example, for dialyser housings. The invention therefore also provides use of the polycarbonate moulding compositions according to the invention for preparing items for medical applications. Polycarbonates according to the invention may be admixed with other thermoplastic materials in conventional amounts, i.e. between 10 wt. % and 50 wt. %, with reference to the polycarbonate according to the invention, mostly for non-transparent applications. Appropriate other thermoplastic materials are, for example, aromatic polyestercarbonates, polycarbonates based on different bisphenols from the polycarbonates according to the invention, polyalkylene terephthalates, EPDM polymers, polystyrene and copolymers and graft copolymers based on styrene such as in particular ABS.
	claims	1. A hazardous material repository, comprising:a drillhole formed from a terranean surface into a subterranean zone that comprises a geologic formation, the drillhole comprising a vertical portion and a non-vertical portion coupled to the vertical portion by a transition portion, the non-vertical portion comprising a storage volume for hazardous waste;a casing installed between the geologic formation and the drillhole, the casing comprising one or more metallic tubular sections formed of API-5CT L80 steel;at least one canister positioned in the storage volume of the non-vertical portion of the drillhole, the at least one canister sized to enclose a portion of hazardous material and comprising an outer housing formed from a nickel-chromium-molybdenum alloy;an engineered filling inserted into the drillhole to fill at least a portion of the storage volume between the at least one canister and the casing, the engineered filling comprising a deaerated bentonite-based slurry; anda backfill material inserted into the at least one canister to fill a void between the portion of hazardous material and the canister, the backfill material comprising a quartz material. 2. The hazardous material repository of claim 1, wherein the hazardous material comprises radioactive material waste. 3. The hazardous material repository of claim 2, wherein the radioactive material waste comprises one or more portions of a spent nuclear fuel assembly. 4. The hazardous material repository of claim 2, wherein the geologic formation is at a depth in which a hydrostatic pressure at the depth is great enough to prevent boiling of water at a boiling point of about 310° C., or the geologic formation comprises pore water that is highly reducing, or the geologic formation comprises a rock in which pore waters are anoxic, or the geologic formation comprises a fully saturated rock formation. 5. The hazardous material repository of claim 1, wherein the nickel-chromium-molybdenum alloy comprises Alloy 625. 6. The hazardous material repository of claim 1, wherein a wall thickness of the at least one canister is between 9.25 mm and 10 mm. 7. The hazardous material repository of claim 6, wherein a wall thickness of the casing is 12.5 mm. 8. The hazardous material repository of claim 1, wherein a wall thickness of the casing is 12.5 mm. 9. The hazardous material repository of claim 1, wherein the bentonite-based slurry is pumped from the terranean surface into the non-vertical portion of the drillhole to fill the portion of the storage volume between the at least one canister and the casing. 10. The hazardous material repository of claim 1, wherein the geologic formation is at a depth in which a hydrostatic pressure at the depth is great enough to prevent boiling of water at a boiling point of about 310° C., or the geologic formation comprises pore water that is highly reducing, or the geologic formation comprises a rock in which pore waters are anoxic, or the geologic formation comprises a fully saturated rock formation. 11. The hazardous material repository of claim 1, wherein a thermal load of the hazardous material repository is controlled by spacing of the at least one canister within the storage volume. 12. The hazardous material repository of claim 1, wherein the nickel-chromium-molybdenum alloy is configured to self-form a passive protective film on an exterior surface of the outer housing of the at least one canister. 13. The hazardous material repository of claim 1, further comprising one or more expansion absorbers placed at predetermined locations in the casing. 14. The hazardous material repository of claim 1, wherein the deaerated bentonite-based slurry is pumped from the terranean surface into the non-vertical portion of the drillhole to fill the portion of the storage volume between the at least one canister and the casing to a level that extends uphole to at or near a drillhole seal that is positioned to isolate an entry of the drillhole at a terranean surface from the storage volume. 15. The hazardous material repository of claim 1, wherein the deaerated bentonite-based slurry comprises an insulator and a radioactive energy absorber between the at least one canister and the casing. 16. A method for forming an engineered barrier system for a hazardous material repository, comprising:forming a drillhole from a terranean surface into a subterranean zone that comprises a geologic formation, the drillhole comprising a vertical portion and a non-vertical portion coupled to the vertical portion by a transition portion, the non-vertical portion comprises a storage volume for hazardous waste;installing a casing between the geologic formation and the drillhole, the casing comprising one or more metallic tubular sections formed of API-5CT L80 steel;positioning at least one canister in the storage volume of the non-vertical portion of the drillhole, the at least one canister enclosing a portion of hazardous material and comprising an outer housing formed from a nickel-chromium-molybdenum alloy, the outer housing defining a volume that encloses the portion of the hazardous material and a backfill material that comprises a quartz material; andinserting an engineered filling into the drillhole to fill at least a portion of the storage volume between the at least one canister and the casing, the engineered filling comprising a deaerated bentonite-based slurry. 17. The method of claim 16, wherein the hazardous material comprises radioactive material waste. 18. The method of claim 17, wherein the radioactive material waste comprises one or more portions of a spent nuclear fuel assembly. 19. The method of claim 16, wherein the nickel-chromium-molybdenum alloy comprises Alloy 625. 20. The method of claim 16, wherein a wall thickness of the at least one canister is between 9.25 mm and 10 mm. 21. The method of claim 20, wherein a wall thickness of the casing is 12.5 mm. 22. The method of claim 16, wherein a wall thickness of the casing is 12.5 mm. 23. The method of claim 16, wherein inserting the engineered filling into the drillhole comprises pumping the bentonite-based slurry from the terranean surface into the non-vertical portion of the drillhole to fill the portion of the storage volume between the at least one canister and the casing. 24. The method of claim 16, wherein the geologic formation is at a depth in which a hydrostatic pressure at the depth is great enough to prevent boiling of water at a boiling point of about 310° C., or the geologic formation comprises pore water that is highly reducing, or the geologic formation comprises a rock in which pore waters are anoxic, or the geologic formation comprises a fully saturated rock formation. 25. The method of claim 16, wherein positioning the at least one canister in the storage volume of the non-vertical portion of the drillhole comprises:positioning a first canister in the storage volume of the non-vertical portion of the drillhole; andpositioning a second canister in the storage volume of the non-vertical portion of the drillhole apart from the first canister a specified distance based on a thermal load of the hazardous material repository. 26. The method of claim 16, further comprising, subsequent to the inserting the engineered filling into the drillhole, sealing the vertical portion of the drillhole from the terranean surface. 27. The method of claim 16, further comprising inserting one or more expansion absorbers at predetermined locations in the casing. 28. The method of claim 16, further comprising forming a passive protective film on an exterior surface of the outer housing by the nickel-chromium-molybdenum alloy.
	description	The present application claims the benefit of Korean Patent Application Nos. 2008-0014861 and 2008-0031979, filed in Korea on Feb. 19, 2008 and Apr. 7, 2008, respectively, both of which are hereby incorporated by reference in their entirety. 1. Field of the Invention Embodiments of the invention relate to a liquid crystal display (LCD) device, and more particularly, to a method of aligning an alignment layer for an LCD device being capable of controlling a pre-tilt angle of a liquid crystal layer and an LCD device having an alignment layer aligned by the same. 2. Discussion of the Related Art Liquid crystal display (LCD) devices are the subject of significant research and development because of their low power consumption and high value. Among the known types of LCD devices, active matrix LCD (AM-LCD) devices, which have thin film transistors (TFTs) arranged in a matrix array, are the subject of significant research and development because of their high resolution and superior ability in displaying moving images. Each of the TFTs can be controlled to have ON or OFF state. Generally, the LCD device is fabricated though an array substrate fabricating process, a color filter substrate fabricating process and a liquid crystal (LC) cell process. In the array substrate fabricating process, array elements, such as a TFT, a pixel electrode and so on, are formed on a first substrate. In the color filter substrate fabricating process, a color filter and a common electrode are formed on a second substrate. In the LC cell process, after the first and second substrates are attached, an LC layer is provided between the first and second substrates. FIG. 1 is an exploded perspective view of a related art LCD device. The related art LCD device includes first substrate 12, second substrate 22, and a liquid crystal layer 30. The first and second substrates 12 and 22 face each other, and the liquid crystal layer 30 is interposed therebetween. The first substrate 12 includes a gate line 14, a data line 16, a TFT “Tr”, and a pixel electrode 18. The gate line 14 and the data line 16 cross each other such that a pixel region “P” is defined between the gate and data lines 14 and 16. The TFT “Tr” is formed adjacent to a crossing of the gate and data lines 14 and 16, and the pixel electrode 18 is formed in the pixel region “P” and connected to the TFT “Tr”. The second substrate 22 includes a black matrix 25, a color filter layer 26, and a common electrode 28. The black matrix 25 has a lattice shape to cover a non-display region of the first substrate 12, such as the gate line 14, the data line 16, the TFT “Tr”. The color filter layer 26 includes first sub-color filters 26a, second sub-color filters 26b, and third sub-color filter 26c. Each of the sub-color filters 26a, 26b, and 26c has one of red, green, and blue colors R, G, and B and corresponds to the each pixel region “P”. The common electrode 28 is formed on the black matrix 25 and the color filter layers 26 and over an entire surface of the second substrate 22. The first substrate 12, which includes the TFT “Tr”, the pixel electrode 18 and so on, is referred to as an array substrate 10, and the second substrate 22, which includes the color filter layer 26, the common electrode 28 and so on, is referred to as a color filter substrate 20. The LCD device can be fabricated through following processes. First, an array pattern including a plurality of switching elements, a plurality of pixel electrodes, a gate line, a data line and pads is formed on the first substrate. The array pattern can be formed through a deposition process, a photo-lithography process and an etching process. The gate and data lines cross each other to define a pixel region. Each switching element is disposed each pixel region. Each of the plurality of pixel electrodes corresponds to each pixel region and is connected to the switching element. The pads are disposed at an end portion of the gate line and the data line. This process can be referred to as an array substrate fabricating process. Meanwhile, a black matrix and a color filter layer including red, green and blue color filter patterns are formed on the second substrate. A common electrode is formed on the black matrix and the color filter layer to face the pixel electrode on the first substrate. This process can be referred to as a color filter substrate fabricating process. Next, a liquid crystal layer is interposed between the first and second substrate, and then the first and second substrate are attached to each other such that a liquid crystal panel is fabricated. This process can be referred to as a cell process. The LCD device uses electro-optical properties of liquid crystal molecules. The electro-optical properties result from optical anisotropy and arrangement of the liquid crystal molecules. Accordingly, high quality images are obtained by control of the arrangement of the liquid crystal molecules. To control an initial arrangement of the liquid crystal molecules, an aligning process is performed on an alignment layer. The alignment process includes an alignment layer forming process and an aligning process on a surface of the alignment layer. In the alignment layer forming process, an alignment material is coated onto a substrate to form the alignment layer. In the aligning process, the alignment layer is treated to form a polymer chain arranged along one direction. Particularly, in the alignment layer forming process, an alignment material, for example, polyimide, is coated onto a substrate to form the alignment layer having uniform thickness. The substrate can be one of the array substrate and the color filter substrate. In more detail, the alignment layer is disposed at an active region where the liquid crystal layer is formed. Accordingly, when the alignment layer is formed over an entire surface of the substrate by a spin coating method, an etching process is required to remove a portion of the alignment layer at a non-display region about the periphery of the active region. Accordingly, to avoid any additional processes, such as the etching process, the alignment layer is formed on the active region but not on the non-display region by using a transcription plate. The transcription plate is already patterned to correspond to the active regions on the substrate. Next, the substrate including the alignment layer is treated in a drier and a hardening apparatus to remove moisture in the alignment layer and to achieve a desired hardness. Next, a surface of the alignment layer is treated to form a polymer chain arranged along one direction on the surface of the alignment layer. The treatment process can be referred to as a rubbing process. Hereinafter, a related art rubbing process is explained with reference to the accompanying drawings. FIGS. 2A and 2B are plane views and a cross-sectional view showing a related art rubbing process, respectively. In FIG. 2A, a substrate 40 where an alignment layer (not shown) is disposed on a stage of a rubbing apparatus. And then, a rubbing roll 50 is disposed over the substrate 40 and rotated. Rubbing cloth, which is formed of rayon, is wound on the rubbing roll 50. Referring to FIG. 2B, when the rubbing roll 50 is rotated, the rubbing cloth 55 contacts and rubs a surface of the alignment layer 45. When the rubbing cloth 55 contacts the alignment layer 45, the stage 30 or the rubbing roll 50 moves along a direction such that an entire surface of the alignment layer 45 is rubbed by the rubbing cloth 55. As a result, a polymer chain, which is referred to as a side chain, is arranged along a direction on a surface of the alignment layer 45. Due to the side chain, liquid crystal molecules on the surface of the alignment layer 45 have a pre-tilt angle with respect to the alignment layer 45. The pre-tilt angle is defined as an angle between a major axis of the liquid crystal molecule and a surface of the alignment layer or the substrate. In a twisted-nematic (TN) mode LCD device and an in-plane switching (IPS) mode LCD device, the pre-tilt angle can be 0 to 3 degrees. Generally, a horizontal type alignment layer is rubbed such that the liquid crystal molecule has a pre-tilt angle of 0 to 3 degrees. Before the alignment layer is rubbed, a side chain of the horizontal type alignment layer is substantially horizontal to the surface of the alignment layer. On the other hand, in a vertical type alignment (VA) mode LCD device, the liquid crystal molecule has a pre-tilt angle of 89 to 90 degrees. The vertical type alignment layer is first formed and then rubbed. Recently, a new mode of LCD device has been introduced in which the alignment layer is required to be rubbed to have a pre-tilt angle of 20-70 degrees. Namely, the alignment layer is required to be capable of having a controllable pre-tilt angle. To meet the requirement, blending of polymer materials having different properties have been researched. However, since the blending is very difficult, there is no practical use. Moreover, a controllable pre-tilt angle can be obtained by forming a horizontal type alignment layer and a vertical type alignment layer with controlled rubbing densities on each of them. However, such a process requires forming alignment layers at least twice. Accordingly, there are problems that production time and production costs increase. In addition, a controllable pre-tilt angle may be obtained by using transcription plates having different patterns. However, the transcription plate has ductility such that there is no reliability. On the other hand, at least two rubbing processes cause some other problems. When the rubbing cloth contacts the alignment layer, a hair of a surface of the rubbing cloth is separated such that particles are generated. Moreover, because the rubbing cloth itself generates fine dusts, there are some problems in a fabricating process of the LCD device where an excellent cleaning is required. Further, disconnection of the electrical lines on the substrate and degradation of properties in the switching element can occur due to static electricity being generated between the rubbing cloth and the alignment layer. Furthermore, as the substrate becomes larger, the rubbing cloth is required to be longer. When the longer rubbing cloth is rotated, an eccentric force increases that causes vibrations in the rubbing roll to also increase. Such vibrations cause the aligning properties of the resultant alignment film to be non-uniform. Recently, the LCD device is required to have fast response time and a wide viewing angle. To meet these requirements, an optically compensated bend (OCB) mode LCD device has been introduced. Due to symmetrical arrangement in liquid crystal molecules with respect to a center line in a liquid crystal layer, a compensating plate is not required. Accordingly, there is an advantage in production cost. FIGS. 3A to 3C are schematic cross-sectional views showing arrangements of liquid crystal molecules in a related art OCB mode LCD device, respectively. FIGS. 3A to 3C respectively show a splay state, a bend-I state and a bend-II state. The OCB mode LCD device includes a first substrate 60, a second substrate 70 and a liquid crystal (LC) layer 80 therebetween. A first alignment layer 62 is disposed over the first substrate 60, and a thin film transistor (not shown) as a switching element and a pixel electrode (not shown) are disposed between the first alignment layer 62 and the first substrate 60. A second alignment layer 72 is disposed over the second substrate 70, and a color filter layer (not shown) and a common electrode (not shown) are disposed between the second alignment layer 72 and the second substrate 70. The LC layer 80 including liquid crystal (LC) molecules 82 and 84 are disposed between the first and second alignment layers 62 and 72. In FIG. 3A showing the splay state where voltages are not applied, first LC molecules 82 adjacent to one of the first alignment layer 62 and the second alignment layer 72 are symmetric to each other with respect to a second LC molecule 84 in a center of the LC layer 80. In this case, a first pre-tilt angle θ1 of the first LC molecules 82 is about 1 degree to about 3 degrees with respect to one of the first and second alignment layers 62 and 72 (or first and second substrates 60 and 70). On the other hand, the second LC molecule 84 is substantially parallel to one of the first and second alignment layers 62 and 72 (or first and second substrates 60 and 70). When a first voltage is applied, the OCB mode LCD device has the bend-I state in FIG. 3B. The first voltage may be referred to as an initial voltage. In the bend-I state, the OCB mode LCD device has an ON state and displays a white image. In this case, the first LC molecules 82 has a second pre-tilt angle θ2 greater than the first pre-tilt angle θ1 in the splay state. The second LC molecule 84 is arranged to be substantially perpendicular to one of the first and second substrates 60 and 70. On the other hand, when a second voltage being greater than the initial voltage is applied, the OCB mode LCD device has the bend-II state in FIG. 3C. The second voltage can be referred to as a driving voltage. In the bend-II state, the OCB mode LCD device has an OFF state and displays a black image. In this case, the first LC molecules 82 has a third pre-tilt angle θ3 greater than the second pre-tilt angle θ2 in the bend-I state. The second LC molecule 84 is arranged to be substantially perpendicular to one of the first and second substrates 60 and 70. Referring to FIG. 4 showing relation between states of the OCB mode LCD device and applying voltages, since the OCB mode LCD device can displays images in the bend-I state and the bend-II state, it has fast response time. Namely, when the driving voltage is applied to the LC molecules in the bend-I state where the LC molecules adjacent to the first and second alignment layers have the second pre-tilt angle being greater than the first pre-tilt angle in the splay state, it is possible to obtain fast response time. However, since the LC molecules have to be the bend-I state, it is required to apply the initial voltage, which causes an increase in power consumption. Accordingly, embodiments of the invention are directed to a method of aligning an alignment layer and a liquid crystal display device having an alignment layer aligned by the same that substantially obviates one or more of the problems due to limitations and disadvantages of the related art. An object of embodiments of the invention is to provide a liquid crystal layer in a bend-I state of an optically compensated bend mode for a liquid crystal display device. Another object of embodiments of the invention is to provide a method for forming a single alignment layer capable of controlling a pre-tilt angle of a liquid crystal layer. Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. To achieve these and other advantages and in accordance with the purpose of embodiments of the invention, as embodied and broadly described, a method of aligning an alignment layer for a liquid crystal display device includes forming an alignment layer on a substrate such that the alignment layer has side chains protruding from a surface of the alignment layer, positioning the substrate with alignment layer on a stage of an ion beam irradiating apparatus, forming a non-altered area in the alignment layer by switching OFF an ion generator while one of the stage and ion generator is moving, and forming an ion-altered area in the alignment layer by switching ON the ion generator while the one of the stage and ion generator is stopped. In another aspect, a liquid crystal display device includes: a first substrate having a black matrix, a color filter layer and a common electrode; a second substrate having gate lines, data lines and thin film transistors connected to pixel electrodes; a first alignment layer on the first substrate; a second alignment layer on the second substrate; and a liquid crystal layer having a plurality of liquid crystal molecules and positioned between the first and second alignment layers, wherein each of the first and second alignment layers has a first area with ion-altered side chains and a second area with non-altered side chains. In another aspect, a method of aligning an alignment layer for a liquid crystal display device includes forming an alignment layer on a substrate such that the alignment layer has side chains protruding from a surface of the alignment layer, positioning the substrate with alignment layer on a stage of an ion beam irradiating apparatus, forming an ion-altered area in the alignment layer by stopping one of the stage and ion generator while an ion generator is turned ON in a first interval, and forming a non-altered area in the alignment layer by moving one of the stage and ion generator while the ion generator is turned ON in a second interval shorter than the first interval. In yet another aspect, a liquid crystal display device includes: a first substrate having a black matrix, a color filter layer and a common electrode; a second substrate having gate lines, data lines and thin film transistors connected to pixel electrodes; a first alignment layer on the first substrate; a second alignment layer on the second substrate; and a liquid crystal layer of liquid crystal molecules positioned between the first and second alignment layers, wherein the liquid crystal molecules include first liquid crystal molecules at a first pre-tilt angle adjacent to one of the first and second alignment layers, second liquid crystal molecules at a second pre-tilt angle adjacent to the one of the first and second alignment layers, and third liquid crystal molecules at a third pre-tilt angle, which is smaller than the first pre-tilt angle and greater than the second pre-tilt angle, adjacent to the first and second liquid crystal molecules. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. Reference will now be made in detail to the preferred embodiments, examples of which are illustrated in the accompanying drawings. FIG. 5 is a schematic perspective view showing an ion beam irradiating apparatus for aligning an alignment layer having a controllable pre-tilt angle according to embodiments of the invention. An ion beam irradiating apparatus for a method of aligning an alignment layer will be explained with reference to FIG. 5. As shown in FIG. 5, the ion beam irradiating apparatus 100 includes a chamber 150, an ion generator 110 inside the chamber 150 and a stage 140 for receiving a substrate. The chamber 150 is connected to a vacuum pump (not shown) via a pipe 155 to provide a vacuum. A gas supplying pipe 130 is connected to the ion generator 110 to supply gases for generating ions. During the irradiation of ions onto the substrate 145, the chamber 150 has a vacuum within a range of about 10−7 Torr to about 760 Torr (atmospheric pressure). The ion generator 110 includes a plasma generating unit 115, an accelerating electrode 120 and an ion exhausting portion 123. The plasma generating unit 115 dissociates gases supplied from the gas supplying pipe 130 into ions, and the ions generated from the plasma generating unit 115 are exhausted through the ion exhausting portion 123. Before being exhausted, the ions are accelerated by the accelerating electrode 120 to have pre-determined velocity and energy. The ion exhausting portion 123 has a width equal to or smaller than the width of the substrate 145. When an inert gas is supplied into the ion generator 110 and a high voltage is applied to the plasma generating unit 115, plasmas are generated and the inert gas is dissociated. As a result, the ions are generated. And then, the ions are accelerated by the accelerating electrode 120. The accelerated ions are provided into the chamber 150 through the ion exhausting portion 123 having a grid shape. The ions collide into the alignment layer (not shown) on the substrate 145 in the chamber 150 such that a side chain of the alignment layer (not shown) is altered. And then, the ions are exhausted via the pipe 155 from the chamber 150. The inert gas includes one of helium (He), neon (Ne), argon (Ar), krypton (Kr) and xenon (Xe). Considering cost, the inert gas can be Ar. At least one of the ion generator 110 and the stage 140 is movable along a first direction. (In FIG. 5, the stage 140 is movable along the first direction.) Irradiation of ions onto the substrate 145 can be stopped during moving in the first direction. When the ion exhausting portion 123 has a width being equal to or smaller than the substrate 145, the ion generator 110 can move across an entire surface of the substrate 145 along the second direction. When ions are irradiated during a very short interval, such as less than 0.1 sec, or the ion generator 110 is turned OFF while moving the ion generator 110 along the substrate 145 in the first direction, the surface of the substrate 145 in front of the ion exhausting portion 123 is non-altered. On the other hand, when ions are irradiated during a long interval, such as more than 0.1 sec, the surface of the substrate 145 in front of the ion exhausting portion 123 is irradiated. Particularly, when the ion generator 110 or the stage 140 is stopped while the ion generator 110 is turned ON, ion-altered areas “IA” are formed on the substrate 145. The ion-altered areas “IA” are formed in an alignment layer (not shown) on the substrate 145. When the ion generator 110 or the stage 140 moves, the ion generator 110 is turned OFF to stop generating ions or a turned ON ion generator 110 is moved quickly to form a non-altered area in the alignment layer on the substrate 145. When the ion generator 110 or the stage 140 stops again, a turned ON ion generator 110 generates the ions to form another ion-altered area “IA”. Accordingly, the non-altered area is disposed between two adjacent ion-altered areas “IA”. Further, an ion-altered area “IA” can also be disposed between two adjacent non-altered areas. Hereinafter, an aligning method according to embodiments of the invention is explained. FIGS. 6A and 6B show fabricating processes of an alignment layer having a controllable pre-tilt angle using an ion beam irradiating apparatus in FIG. 5, and FIGS. 7A and 7B are schematic perspective views showing a surface of an alignment layer before and after aligning method according to embodiments of the invention. In FIG. 6A, an alignment layer 230 is formed on a substrate 220 disposed on a stage 205. The alignment layer 230 has a side chain extending perpendicular to a surface of the alignment layer 230. Thus, the alignment layer 230 is a vertical type alignment layer. The substrate 220 can be one of an array substrate and a color filter substrate for an LCD device. When the substrate 220 is the array substrate, gate and data line (not shown) crossing each other, a thin film transistor (not shown) as a switching element, and a pixel electrode (not shown) connected to the thin film transistor (not shown) are formed on the array substrate. On the other hand, when the substrate 220 is the color filter substrate, a color filter layer (not shown) and a common electrode (not shown) are formed on the color filter substrate. In the LCD device, the array substrate and the color filter substrate are attached with a liquid crystal layer therebetween. The alignment layer 230 can be formed by using an alignment printing apparatus 200. The alignment printing apparatus 200 includes a doctor roll 212, a doctor blade (not shown), an anilox roll (210), a printing roll 208 and a stage 205. A transcription plate 215 is attached onto a surface of the printing roll 208. A polymer material for the alignment layer 230 is coated on the transcription plate 215 by the anilox roll 210, and then the printing roll 208 is rotated and the stage 205 moves along a direction such that the transcription plate 215 contacts a surface of the substrate 220. As a result, the alignment layer 230 is formed on the surface of the substrate 220 to have a desired shape. And then, the substrate where the alignment layer 230 is formed is treated in a drier and a hardening apparatus such that the alignment layer 230 has a desired thickness, for example, about 500 angstroms to about 1500 angstroms, and a desired hardness, for example, about 1 hardness (H) to about 4 hardness (H). Referring to FIG. 7A, the alignment layer 230, which is formed through the above-mentioned process, on the substrate 220 includes a base layer (not shown). In the base layer, main chains are entangled with each other such that the base layer has an upper surface being substantially parallel to an upper surface of the substrate 220. Further, side chains 240 protruding from the base layer. Since the alignment layer is a vertical type, the side chains 240 are substantially perpendicular to the upper surface of the base layer. For example, the side chains 240 have an angle of about 87 degrees to about 90 degrees with respect to the surface of the substrate 220. Referring to FIGS. 6B and 7B, an ion beam 277 is irradiated onto the alignment layer 230 having the side chains 240 (of FIG. 7A) by using the ion beam irradiating apparatus 260. As mentioned above, the ion beam irradiating apparatus 260 includes a chamber 263, an ion generator 266 inside the chamber 263 and a stage 285 on which the substrate 220 is disposed. The chamber 263 is connected to a vacuum pump (not shown) via a pipe 280 to provide a vacuum. A gas supplying pipe 278 is connected to the ion generator 266 to supply gases for generating ions. The ion generator 266 includes a plasma generating unit 269, an accelerating electrode 272 and an ion exhausting portion 275. The stage 285 or the ion generator 266 is movable. The stage 285 or ion generator 266 moves and stops. Thus, the ion generator 266 can be switched ON such that the ion beam 277 forms an ion-altered area in the alignment layer 230 during a stop and is moved quickly across a portion of the alignment layer 230 while still being switched ON to form a non-altered area in the alignment layer 230. In the alternative, the ion generator 266 is switched OFF while the stage 285 or ion generator 266 is moving to form a non-altered area in the alignment layer 230, and the ion generator 266 is switched ON while the stage 285 or ion generator 266 is stopped to form an ion-altered area in the alignment layer 230. In more detail, when the substrate 220 where the alignment layer 230 is formed is disposed on the stage 285 of the ion beam irradiating apparatus 260, the chamber 263 is put in a vacuum state by the vacuum pump (not shown) via the pipe 280. The degree of vacuum in the chamber 263 can be within a range of about 10−7 Torr to about 760 Torr. Subsequently, an inert gas is supplied into the ion generator 266, and ions are generated by the plasma generating unit 269. The ions are accelerated by the accelerating electrode 272, and the accelerated ions are exhausted through the ion exhausting portion 275. The exhausted ions through the ion exhausting portion 275 is referred to as the ion beam 277. The ion beam 277 is irradiated onto the alignment layer 230. The ion beam 277 has about 1011 to about 1013 doses per square centimeter (cm2) and has an energy of about 50 eV to about 2000 eV. The ions are accelerated by using a voltage of about 100 V to about 10 kV. The ion beam 277 can have an angle of about 30 degrees with respect to the surface of the substrate 220. When the stage 285 moves while the ion generator 266 is an OFF state, a first area “A” remains on the alignment layer 230. Since the ion beam 277 is not irradiated onto the first area “A”, the side chain 240 remains in the first area “A”. On the other hand, when the stage 285 is stopped and the ion generator 266 is in an ON state, a second area “B” is formed onto the alignment layer 230. Since the ion beam 277 is irradiated onto the second area “B”, the side chain 240 is altered in the second portion “B”. The ion beam 277 is irradiated onto the second area “B” within an interval of about 0.1 sec to about 300 sec. The first and second areas “A” and “B” are alternately disposed with each other. Width of the first and second areas “A” and “B” are controlled depending on a desired range of pre-tilt angle of liquid crystal (LC) molecules. Referring to FIG. 8 showing an initial arrangement of liquid crystal molecules on an aligned alignment layer, first LC molecules 292a adjacent to a surface of the alignment layer 230 and in the second area “B”, where the side chains 240 are altered, and a second LC molecules 292b adjacent to a surface of the alignment layer 230 and in the first area “A”, where the side chains 240 exists, have different pre-tilt angles. Since the side chains 240 are altered in the second area “B”, the first LC molecules 292a have a first pre-tilt angle (not shown) of about 0 degree with respect to the alignment layer 230. Namely, a major axis of the first LC molecule 292a is substantially parallel to the alignment layer 230. On the other hand, since the side chains 240 exists in the first area “A”, the second LC molecules 292b have a second pre-tilt angle (not shown) of about 90 degrees. Namely, a major axis of the second LC molecule 292b is substantially perpendicular to the alignment layer 230. A third LC molecules 292c adjacent to the first and second LC molecules 292a and 292b have a third pre-tilt angle “θ” greater than the first and second pre-tilt angles (not shown) because all of the LC molecules have an elastic property. Since a large portion of the LC molecules adjacent to the alignment layer 230 is the third LC molecules, the third LC molecules have a third pre-tilt angle “θ” are in mass since there are more third LC molecules than either first or second molecules. FIG. 9 is a graph showing a pre-tilt angle of a liquid crystal molecule on an alignment layer depending on an ion beam exposure time. A pre-tilt angle of a first LC molecule 292a (of FIG. 8) in the second area “B” (of FIG. 8) strongly depends on an ion beam exposure (irradiating) time. When the alignment layer is exposed to the ion beam by an interval being greater than about 20 sec, the first LC molecule 292a (of FIG. 8) has a pre-tilt angle of about 0 degree. On the other hand, when the alignment layer is not exposed to or is exposed to the ion beam by an interval being smaller than about 2 sec, the first LC molecule 292a (of FIG. 8) has a pre-tilt angle of about 90 degree. When the alignment layer is exposed by an interval between about 2 sec to about 20 sec, the first LC molecule 292a (of FIG. 8) has a pre-tilt angle within a range of about 0 degree to about 90 degree. Particularly, when the alignment layer is exposed by an interval between about 5.5 sec to about 12.5 sec, the first LC molecule 292a (of FIG. 8) has a pre-tilt angle within a range of about 40 degree to about 70 degree. FIG. 10 is a schematic cross-sectional view of an OCB mode LCD device according to an embodiment of the invention. In FIG. 10, an OCB mode LCD device 300 includes a first substrate 310, a second substrate 320 and a liquid crystal (LC) layer 330. The first and second substrates 310 and 320 face each other. The LC layer 330 is interposed therebetween and includes a plurality of LC molecules 332a, 332b, 332c and 334. The LC molecules 334 are disposed at a center of the LC layer 330. Although not shown, a plurality of gate lines and a plurality of data lines, a thin film transistor as a switching element and a pixel electrode are formed on the first substrate 310. The plurality of gate lines and the plurality of data lines cross each other to define a pixel region, and the thin film transistor is disposed at each pixel region. The pixel electrode is connected to the thin film transistor. A black matrix, a color filter layer including red, green and blue color filters, and a common electrode are formed on the second substrate 320. The black matrix corresponds to a non-display region, for example, the gate lines, the data line and the thin film transistor to shield light. Each of the red, green and blue color filters corresponds to each pixel region. The common electrode is formed on the black matrix and the color filter layer. The LC molecules 332a, 332b, 332c and 334 are driven by an electric field induced between the pixel and common electrodes. In addition, first and second alignment layers 312 and 322 are formed over the first and second substrates 310 and 320, respectively. In more detail, the first and second alignment layers 312 and 322 are formed on the pixel and common electrodes, respectively. The first and second alignment layers 312 and 322 face each other such that the liquid crystal layer 330 is disposed therebetween. Each of the first and second alignment layers 312 and 322 functions in determining an initial arrangement of the LC molecules 332a, 332b, 332c and 334. The first and second alignment layers 312 and 322 can be formed of a vertical type polyimide. In the OCB mode LCD device, there is characteristics in the arrangements of the LC molecules 332a, 332b and 332c adjacent to the first and second alignment layers 312 and 322. Here, the LC molecules adjacent to the first alignment layer are explained. First LC molecules 332a are initially arranged to be perpendicular to the first alignment layer 312 (or the first substrate 310). Namely, the first LC molecules 332a have a first pre-tilt angle (not shown) of about 90 degree with respect to the first alignment layer 312. Second LC molecules 332b are arranged to be parallel to the first alignment layer 312 (or the first substrate 310). Namely, the second LC molecules 332b have a second pre-tilt angle (not shown) of about 0 degree with respect to the first alignment layer 312. In addition, third LC molecules 332c disposed adjacent to the first and second LC molecules 332a and 332b are oblique to the first alignment layer 312 (or the first substrate 310). Namely, the third LC molecules 332c have a third pre-tilt angle θ within a range of about 20 to about 70 degree because the LC molecules have an elastic property. Accordingly, the average of the pre-tilt angle for the LC molecules 332a, 332b and 332c is about 20 to 70 degrees. The first LC molecules 332a are disposed in a first area “A”. Since an ion beam is not irradiated onto the first area “A” and the alignment layer 312 is a vertical type alignment layer, side chains, which protrude to be perpendicular to the first alignment layer 312, remain such that the first LC molecules 332a have the first pre-tilt angle of about 90 degrees. Second LC molecules 332b are disposed in the second area “B”. Since the second area “B” is exposed to an ion beam, side chains are altered such that the second LC molecules 332b have the second pre-tilt angle of about 0 degree. As mentioned above, since the LC molecules have an elastic property, the third LC molecules 332c adjacent to the first and second LC molecules 332a and 332b have the third pre-tilt angle θ smaller than the first pre-tilt angle and greater than the second pre-tilt angle θ. Since a large portion of LC molecules adjacent to the alignment layer correspond to the third LC molecules 332c, it can be said that the third LC molecules having the third pre-tilt angle θ are in mass since there are more third LC molecules than either first or second LC molecules. The pre-tilt angle corresponds to an initial arrangement. As explained, the OCB mode LCD device has advantages in response time and viewing angle. Unfortunately, since the related art OCM mode LCD device requires an initial voltage, there is a disadvantage in power consumption. However, in the OCB mode LCD device, since the LC molecules have a pre-tilt angle of about 20 to 70 corresponding to a pre-tilt angle in a bend-I state, it is possible to obtain fast response time without applying an initial voltage. Accordingly, the problem of large power consumption is overcome. Moreover, since the LC molecules are symmetrically arranged with respect to a center line of the liquid crystal layer, a compensating plate is not required. Accordingly, there is an advantage in production cost. In another embodiment, the second LC molecules 332b in the second area “B” where the ion beam is irradiated can have a second pre-tilt angle above 0 degree. Namely, the side chain in the second area “B” is altered such that the second LC molecules 332b in the second area “B” have the second pre-tilt angle above 0 degree. For example, the second LC molecules 332b have the second pre-tilt angle within a range of about 10 degrees to about 20 degrees. If other conditions are same, the third pre-tilt angle θ of the third LC molecules 332c depends on the second pre-tilt angle of the second LC molecules 332b. The second pre-tilt angle can be controlled by an ion beam exposure time or a density of the ion beam. Further, the third pre-tilt angle of the third LC molecules 332c can be controlled by controlling a ratio of an area of the first area “A” to an area of the second area “B”. The third pre-tilt angle θ of the third LC molecules 332c is in proportion to the ratio of the area of the first area “A” to the area of the second area “B”. Namely, as the first area “A” has the larger area, the third LC molecules 332c has a larger pre-tilt angle. It is experimentally known that the third LC molecules 332c have a pre-tilt angle θ within a range of about 30 degrees to about 60 degrees when a ratio of an area of the first area “A” to an area of the second area “B” is 0.5˜3:1 and the second LC molecules have a pre-tilt angle of about 0 degree. Moreover, a pre-tilt angle θ of the third LC molecules 332c can be controlled by controlling a pre-tilt angle of the second LC molecules and a ratio of an area of the first area “A” to an area of the second area “B”. It will be apparent to those skilled in the art that various modifications and variations can be made in the organic electroluminescent device and fabricating method thereof of embodiments of the invention without departing from the spirit or scope of the invention. Thus, it is intended that embodiments of the invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.
	abstract	An X-ray source with optical indication of radiation, which can be used in various measuring devices for parameters control and visualization of structure of industrial and biological objects, is proposed. The source comprises a vacuum housing, an anode irradiated by electrons and generating the divergent flux of radiation, an exit window for X-ray radiation, means for optical indication of X-ray radiation beam including a source of optical radiation and an optical mirror. The anode is made composite in the form of a thin film and a radiolucent substrate luminescent in the optical range. The anode structure is an exit window of the source, and behind it the coaxially arranged means of collimation and focusing of X-ray and optical radiation and means of optical visualization of X-ray focus are mounted. The proposed device significantly increases the accuracy and informativity of optical indication of X-ray radiation parameters.
059129395	claims	1. A microfluoroscope comprising: a plasma source of soft x-rays for producing diverging plasma radiation; a fluorescent screen placed at a distant plane to receive diverging plasma radiation; means for placing a specimen in close proximity to the distant plane so that an x-ray absorption shadow of the specimen is projected onto the fluorescent screen; and an optical microscope for viewing fluorescent light emitted by the fluorescent screen corresponding to the x-ray absorption shadow of-the specimen. the fluorescent screen is fine grained. the fluorescent screen is grainless. the fluorescent screen is a single-crystal scintillator. the means for placing a specimen in close proximity to the distant plane places the specimen in contact with the fluorescent screen. the fluorescent screen is very thin and transparent to visible or ultraviolet light so that a high-numerical-aperture optical microscope objective can closely approach and view the fluorescent screen. the plasma source is in a vacuum; and an x-ray transparent vacuum window is used to separate the specimen, fluorescent screen, and microscope from the vacuum of the plasma source. filters are used to limit the wavelengths of soft x-rays which reach the fluorescent screen to the desired energy range. the filters are monochromator devices. the plasma source for producing diverging plasma radiation includes a laser-produced plasma. the plasma source of soft x-rays is an x-ray laser. the soft x-rays are in the water window wavelength range. the specimen is living. the fluorescent screen emits ultraviolet fluorescence and the microscope has an objective lens which is compatible with UV light. a plasma source of soft x-rays for producing diverging plasma radiation; an x-ray relay optic aligned to collect at least part of the diverging plasma radiation and redirect part of the diverging plasma radiation to the focal plane of the conventional microscope; a fluorescent screen placed at the focal plane of the conventional microscope to receive the redirected part of the diverging plasma radiation; means for placing a specimen in close proximity to the focal plane of the conventional microscope so that an x-ray absorption shadow of the specimen is projected onto the fluorescent screen for examination by the conventional optical microscope. the optical microscope has visible light condenser optics for performing standard light microscopy. the plasma radiation is unobstructed by utilizing removable light condenser optics. multilayer mirrors are used in conjunction with the x-ray relay optic for redirecting the plasma radiation. the optical microscope has confocal optics. the optical microscope has fluorescence contrast capabilities. the optical microscope has phase contrast capabilities. the optical microscope has interference contrast capabilities. a miniaturized plasma source of soft x-rays placed between the microscope condenser optics and the microscope objective-lens; a fluorescent screen placed at the focal plane of the conventional microscope to receive diverging plasma radiation; means for placing a specimen in close proximity to the focal plane of the conventional microscope so that an x-ray absorption shadow of the specimen is projected onto the fluorescent screen. the miniaturized plasma source uses a laser-produced plasma. a plasma source of soft x-rays for producing diverging plasma radiation; an x-ray relay optic aligned to collect at least part of the diverging plasma radiation and redirect part of the diverging plasma radiation to a distant plane; a fluorescent screen placed at the distant plane to receive the redirected part of the diverging plasma radiation; means for placing a specimen in close proximity to the distant plane so that an x-ray absorption shadow of the specimen is projected onto the fluorescent screen; and an optical microscope for viewing fluorescent light emitted by the fluorescent screen corresponding to the x-ray absorption shadow of the specimen. the fluorescent screen is fine grained. the fluorescent screen is grainless. the flourescent screen is a single crystal scintillator. the means for placing a specimen in close proximity to the distant plane places the specimen in contact with the fluorescent screen. the fluorescent screen is very thin and transparent to visible or ultraviolet light so that a high numerical-aperture optical microscope objective can closely approach and view the screen. the plasma source is in a vacuum; and an x-ray transparent vacuum window is used to separate the specimen, fluorescent screen, and microscope from the vacuum of the plasma source. filters are used to limit the wavelengths of soft x-rays which reach the fluorescent screen to the desired energy range. the filters are monochromator devices. the plasma source of soft x-rays is an x-ray laser. the soft x-rays are in the water-window wavelength range. the specimen is living. the fluorescent screen emits ultraviolet fluorescence and the microscope has an objective lens which is compatible with UV light. x-ray optics are used to collimate the plasma radiation. the relay optics are a hollow capillary tube. the optical microscope has visible light condenser optics for performing standard light microscopy. the plasma radiation is unobstructed by utilizing removable light condenser-optics. multilayer mirrors are used in conjunction with the x-ray relay optic for redirecting the plasma radiation. a conventional microscope; a plasma source of soft x-rays for producing diverging plasma radiation; an x-ray relay optic aligned to collect at least part of the diverging plasma radiation and redirect part of the diverging plasma radiation to the plane of the conventional microscope; a fluorescent screen placed at the plane of the conventional microscope to receive the redirected part of the diverging plasma radiation; means for placing a specimen in close proximity to the plane of the conventional microscope so that an x-ray absorption shadow of the specimen is projected onto the fluorescent screen. the optical microscope has confocal optics. the optical microscope has fluorescence capabilities. the optical microscope has phase contrast capabilities. the optical microscope has interference capabilities. 2. A microfluoroscope according to claim 1 and herein: 3. A microfluoroscope according to claim 1 and wherein: 4. A microfluoroscope according to claim 1 and wherein: 5. A microfluoroscope according to claim 1 and wherein: 6. A microfluoroscope according to claim 1 and wherein: 7. A microfluoroscope according to claim 1 and wherein: 8. A microfluoroscope according to claim 1 and wherein: 9. A microfluoroscope according to claim 8 and wherein: 10. A microfluoroscope according to claim 1 and wherein: 11. A microfluoroscope according to claim 1 and wherein: 12. A microfluoroscope according to claim 1 and wherein: 13. A microfluoroscope according to claim 1 and wherein: 14. A microfluoroscope according to claim 1 and wherein: 15. The combination with a conventional optical microscope for examining a specimen at a plane by microfluoroscopy comprising: 16. The combination according to claim 15 and wherein: 17. A combination according to claim 15 and wherein: 18. The combination according to claim 15 and wherein: 19. The combination according to claim 15 and wherein: 20. The combination according to claim 15 and wherein: 21. The combination according to claim 15 and wherein: 22. The combination according to claim 15 and wherein: 23. The combination with a conventional light microscope for examining a specimen by microfluoroscopy at a plane comprising; 24. The invention according to claim 23 and wherein: 25. A microflouroscope comprising: 26. A microflouroscope according to claim 25 and wherein: 27. A microflouroscope according to claim 25 and wherein: 28. A microflouroscope according to claim 25 and wherein: 29. A microflouroscope according to claim 25 and wherein: 30. A microflouroscope according to claim 25 and wherein: 31. A microflouroscope according to claim 25 and wherein: 32. A microflouroscope according to claim 25 and wherein: 33. A microflouroscope according to claim 32 and wherein: 34. A microflouroscope according to claim 25 and wherein: 35. A microflouroscope according to claim 25 and wherein: 36. A microflouroscope according to claim 25 and wherein: 37. A microflouroscope according to claim 25 and wherein: 38. A microflouroscope according to claim 25 and wherein: 39. A microflouroscope according to claim 25 and wherein: 40. A microflouroscope according to claim 25 and wherein: 41. A microflouroscope according to claim 40 and wherein: 42. A microflouroscope according to claim 25 and wherein: 43. The combination for examining a specimen at a plane comprising: 44. A microflouroscope according to claim 43 and wherein: 45. A microflouroscope according to claim 43 and wherein: 46. A microflouroscope according to claim 43 and wherein: 47. A microflouroscope according to claim 43 and wherein:
	abstract	According to an installation method of a water-chamber working apparatus of the present invention, the water-chamber working apparatus includes a base that holds heat transfer tubes on a tube plate surface and is fixed to the tube plate surface, and a manipulator that is coupled with the base, suspended in a water chamber and arranged therein, and has a separable configuration. In this case, a base installing step of installing the base on the tube plate surface and a manipulator coupling step of carrying the separated manipulator (a front stage and a rear stage) into the water chamber sequentially and individually and coupling the manipulator with the base (a coupling link) are performed.
	description	The invention generally relates to nuclear reactors, and in particular to the drive mechanisms of the members controlling the reactivity of the core. More specifically, the present disclosure relates to a nuclear reactor of the type comprising: a vessel having a center axis, containing a primary liquid; a plurality of nuclear fuel assemblies, forming a core placed in the vessel; a plurality of members for controlling the reactivity of the core; a plurality of drive mechanisms of the control members parallel to the center axis; wherein each drive mechanism comprises: a motor comprising a stator and a rotor that may be rotated by the stator; a driving member comprising a driving part forming one of a screw or a nut; a device for connecting in rotation the member driving the rotor, and having a member for applying a rotary torque of the rotor to the driving member; a driven member connected in translation to one of the control members and comprising the other of a screw or a nut, wherein the screw and the nut interact so that rotation of the driving member with respect to the stator is in the form of a translation of the member driven parallel to the center axis with respect to the stator; a blocking device comprising at least one selectively movable blocking member between a blocking position in which the drive member is blocked in translation parallel to the center axis relative to the rotor, and a releasing position in which the driving member and the driven member are free in translation parallel to the center axis with respect to the rotor between an extreme high position and an extreme low position. Such a nuclear reactor is known from EP0034517. The drive mechanisms of this reactor are located outside the vessel, so that the nuclear reactor has a significant height. Moreover, these mechanisms have significant diameters, so that the number of control members that may be implemented in the nuclear reactor is greatly limited. This is particularly problematic when the nuclear reactor operates with a primary liquid free of boron. In this context, the invention aims to provide a nuclear reactor that solves the above problem. To this end, a nuclear reactor of the aforementioned type is provided, characterized in that in each drive mechanism: the motor is fully immersed in the primary liquid inside the vessel; the rotor has a central passage, wherein the member for applying the rotary torque is located in or near the central passage; the driving member comprises a connecting part engaged in the central passage and interacting with the rotary torque application member, wherein the connecting part is free in translation in the central passage relative to the rotor when the, or each, blocking member is in the releasing position. Because the drive mechanisms are fully immersed in the primary liquid inside the vessel, the total height of the nuclear reactor is reduced, since it no longer has structures projecting above the vessel. Furthermore, the member for applying the torque of the rotor to the driving member is located very close to the rotor, or even in the internal passage of the rotor. In EP0034517, the member for applying the torque of the rotor to the driving member is situated at a significant distance from the rotor. The drive mechanism of EP0034517 must include a hollow shaft transmitting the torque of the rotor to the rotational torque application member. The mechanism also has to provide a guide in rotation of the hollow shaft, because of the significant cantilever separating the rotor from the rotary torque application member. Such an arrangement significantly increases the radial size of the drive mechanism. These constraints are eliminated in the present disclosure because of the position of the rotary torque application member. Furthermore, the fact that the driving member comprises a connecting part free in translation in the central passage in the event of release, means that the motor does not contribute to the total height of the drive mechanism. The latter depends on the respective lengths of the driving member and the driven member and the extreme high position. Thus, it is possible to arrange the coils of the rotor and the stator in such a manner as to minimize the outer diameter of the motor, by distributing the conductors over a greater height. The diameter of the drive mechanism may thus be smaller than the pitch of the fuel assemblies, so that it is possible to provide up to one drive mechanism for each fuel assembly. The nuclear reactor may also have one or more of the following characteristics considered individually or in any technically feasible combination: the connecting part of the driving member comprises a first section interacting with the member for applying the rotary torque in the extreme high position, and a second section interacting with the member for applying the rotary torque in the extreme low position; a reactor as described above, wherein the rotary torque application member comprises a plurality of rotatable elements capable of rolling along the connecting part when the connecting part moves parallel to the center axis; the connecting part has at least one flat side on the section perpendicular to the center axis; the passage is delimited by a peripheral wall separated from the connecting part by a gap with a width greater than 10 mm; the, or each, blocking member is mounted on a support integral with the rotor; the blocking device comprises at least one polar mass connected to the, or one of the, blocking member(s) and at least one electromagnetic coil interacting with the, or each, polar mass, wherein the, or each, electromagnetic coil is fixed in translation and in rotation with respect to the stator; the blocking device comprises at least one elastic member interposed between the driving member and the support, and urging the driving member to the extreme low position. each drive mechanism comprises a device for guiding the driven member in translation and blocking the driven member in rotation relative to the stator; each drive mechanism comprises an upper frame on which the motor and the blocking device are mounted, and a lower frame on which is mounted the device for guiding in translation and blocking in rotation, wherein the upper and lower frames are fixed in a removable manner to each other so that the lower frame is closer to the core than the upper frame; the screw and the nut constitute an irreversible connection, arranged so that a vertical bias applied to the driven member is not converted into a rotational movement of the driving member. The nuclear reactor 1 shown in FIG. 1 is a reactor known by the acronym SMR (Small and Medium Reactor). This type of reactor equips, for example, small nuclear facilities, with a power of a few hundred MWe. This reactor is typically of the pressurized water type (PWR). Alternatively, the reactor may be of the boiling water type (BWR). The reactor 1 comprises a vessel 3 having a center axis C, a plurality of nuclear fuel assemblies 5 forming a core 7 placed in the vessel 3, a plurality of core reactivity controllers in the form of members 9 for controlling the reactivity of the core 7, and a plurality of mechanisms 11 for driving the control members 9 parallel to the center axis C. In FIG. 1, only a small number of nuclear fuel assemblies, control members and drive mechanisms are shown. In reality, each nuclear reactor comprises a large number of nuclear fuel assemblies and likewise a large number of control members and drive mechanisms. The center axis C is typically vertical or substantially vertical. The vessel 3 is substantially cylindrical around the center axis C. The vessel 3 contains the primary liquid of the nuclear reactor. Typically, in an SMR type reactor, the pressurizer and the steam generator(s) is/are housed inside the vessel 3. These elements are not shown in FIG. 1. The nuclear fuel assemblies 5 are elongated elements parallel to the center axis, of prismatic shape, and placed against each other. The members 9 for controlling the reactivity of the core are known under the name of control rod or control element. Each comprises a part made of a neutron-absorbing material. Each control member is of elongated shape parallel to the center axis C, and with a section adapted to allow the insertion of the control member in a channel arranged in the center of a nuclear fuel assembly 5. Each drive mechanism 11 is intended to move one of the control members parallel to the center axis C, in order to remove it completely from the corresponding nuclear fuel assembly 5, or to insert it by a given length inside the nuclear fuel assembly. As may be seen in FIG. 2, each drive mechanism 11 comprises: a motor 15 comprising a stator 17 and a rotor 19 capable of being rotated by the stator 17; a driving member 21 comprising a driving part 23 forming one of a screw or a nut; a connector in the form of a connecting device 25 for rotating the driving member 21 with the rotor 19, and having a torquer in the form of a member 27 for applying a rotational torque of the rotor to the driving member; a driven member 29 connected in translation to one of the control members 9 and comprising the other of a screw or a nut; a blocking device 31, comprising at least one blocker in the form of a blocking member 33 selectively movable between a locking position in which the drive member 21 is locked in translation parallel to the center axis C relative to the rotor 19, and a releasing position in which the driving member 21 and the driven member 29 are free in translation parallel to the center axis C relative to the rotor 19. The motors 15 are fully immersed in the primary liquid inside the vessel. More generally, the drive mechanisms 11 are completely immersed in the primary liquid inside the vessel 3. This means that, unlike EP0034517, none of the elements of the drive mechanism protrude outside the vessel 3. In particular, the motor 15, the driving members 21, the driven members 29, and the blocking device 31 are immersed in the primary liquid inside the vessel 3. Typically, all these elements are immersed permanently in the primary liquid. Only electrical conductors connecting the drive mechanism to a source of electrical power or electronic detection devices exit the vessel. The stator 17 has a cylindrical shape, and has an axis A parallel to the center axis C. The rotor 19 is arranged inside the stator 17, and has a cylindrical shape coaxial with the axis A. It has a central passage 35, extending along the axis A. The driving member 21, in addition to the driving part 23, comprises a connecting part 37 engaged in the central passage 35. The driving member 21 is a rod of significant length parallel to the center axis C, wherein the driving part 23 constitutes the lower part of the rod, while the connecting part 37 constitutes the upper part of the rod. The driving part 23 is integral with the connecting part 37. In the present description, the terms inferior and superior, the top and the bottom, the upper and the lower, are understood relative to a vertical direction, corresponding substantially to the center axis C. In the example shown, the driving part 23 forms a screw bearing an external thread 39. This thread extends substantially over the entire length of the driving part 23. In this case, the driven member 29 comprises a tubular part 41, wherein the upper end 43 of the tubular part carries a nut 45. The nut 45 has an internal thread interacting with the external thread 39 of the screw. Alternatively, the driving part 23 carries a nut and the driven member 29 has a part forming a screw and interacting with the nut. The screw 23 and the nut 45 thus interact in such a manner that rotation of the driving member 21 relative to the stator 17 results in a translation of the driven member 29 parallel to the center axis C relative to the stator 17. The interaction of the screw and the nut in normal operation allows the insertion position of the control member 9 in the corresponding fuel assembly 5 to be controlled. Normal operation corresponds to the situation where the blocking member(s) is/are in the locked position. The tubular part 41 has a length parallel to the center axis that is substantially equal to that of the screw 23. Thus, the screw 23 may be received inside the tubular part 41, over all or part of its length, as a function of the position of the nut 45 along the screw 23. The length of the screw corresponds to the maximum stroke of the control member 9 in normal operation. Furthermore, the driven member 29 comprises a fastener 47 connecting the driven member 30 to the control member 9. The fastener 47 is carried by the lower end 49 of the tubular part 41. The rotary torque application member 27 is provided to transmit a rotary torque from the rotor 19 to the driving member 21. The term “application member” as used here refers to the part of the connecting device 25 interacting directly with the driving member 21, and, more specifically, with the connecting part 37 thereof. Advantageously, the application member 27 comprises a plurality of rotary elements 51 able to roll along the connecting part 37 when the latter moves parallel to the center axis. For example, the rotating elements 51 may be rollers. Alternatively, these may be balls or any other type of rotating elements. In another variant, the connection between the rotor 19 and the driving member 21 is provided without a rotary element by means of a male square type connection (rotor side 19)/female square type connection (driving member side 21). The rotating elements are connected to the rotor 19. They are rotatable about respective axes each extending in a plane perpendicular to the center axis C. They are distributed circumferentially around the connecting part 37 of the driving member 21. In order to allow the transmission of the rotational torque, the connecting part 37 has at least one flat side 53 (FIG. 3) in the section perpendicular to the center axis C. Typically, the connecting part 37 has as many flat sides 53 in section as there are rotary elements 51, wherein each rotary element rolls along a flat side 53. In the example shown, the application member 27 comprises four rollers 51 arranged at 90° to each other about the center axis C. Moreover, the connecting part 37 of the driving member 21 has a square section perpendicular to the center axis C. It thus comprises four flat sides 53, perpendicular to each other. Alternatively, the application member 27 may comprise three rotary elements 51, or five rotary elements 51, or more than five rotary elements 51. The rotary torque application member 27 is located in or near the central passage 35. The term “near” means that the application member 27 is located along the center axis at a distance less than 50 cm from the rotor 19. When the application member is not housed in the central passage, it is preferably located under the rotor 19. In a non-preferred variant, it is situated above the rotor 19. Typically, the rotating elements 51 are arranged in housings formed in the rotor 19, and protrude into the passage 35. This situation is illustrated in FIGS. 2 and 3. As a result, the peripheral wall 57 delimiting the passage 35 is separated from the connecting part 37 by a gap having a width greater than 10 mm. Firstly, this has the effect of allowing the circulation of the primary fluid between the drive member 21 and the rotor 19 via the passage 35. This thus reduces the pressure drop for the primary fluid passing through the drive mechanism. This is also favorable for engine cooling. Finally, this reduces the hydromechanical resistance when the driving member 21 and the driven member 29 are released in an emergency. Alternatively, the rotary torque application member 27 does not comprise rotating elements but comprises, for example, one or more pads sliding against the connecting part 37 of the driving member. The blocking member(s) 33 is/are mounted on a support 59 integral with the rotor 19. The support 59 has a cylindrical shape and internally delimits a conduit 60 placed in the extension of the passage 35. The blocking device 31 typically comprises a plurality of blocking members 33 distributed circumferentially around the driving member 21. The blocking device 31 comprises at least one polar mass 61 linked to the blocking member(s) 33, and at least one electromagnetic coil 63 interacting with the polar mass(es) 61. For example, each blocking member 33 may be a hook that is pivotally mounted on the support 59. The blocking device 31 further comprises a rod 64 for each blocking member 33, which is articulated at one end to one of the polar masses 61, and at its opposite end to the hook 33. When the electromagnetic coil 63 is activated, it magnetically attracts the polar mass(es) 61 parallel to the center axis, by bearing against a stop formed on the support 59. In this position, the blocking member(s) 33 protrude inside the conduit 60 and are placed in a groove 65 formed in the driving member 21. The groove 65 is located in an intermediate part of the driving member 21, between the driving part and the connecting part. The groove 65 is delimited upwards by a shoulder 67 bearing against the blocking member(s) 33. The blocking member(s) 33 interact with the shoulder 67 to block the movement of the driving member 21 towards the core 7 parallel to the center axis C. Furthermore, the blocking device 31 also comprises an elastic member 69, interposed between the driving member 21 and the support 59, and urging the driving member 21 towards the core 7. In the example shown, this elastic member is a helical compression spring. When the power supply to the coil 63 is cut off, the polar mass(es) 61 is/are no longer held against the stop provided on the support 59. Elastic members rotate the blocking member(s) 33 in order to withdraw them from the conduit 60. This movement is no longer prevented by the polar mass(es) 61 that is/are held electromagnetically against the stop(s). The driving member 21 is then free to move towards the core 7 under the effect of its weight and the urging force applied by the elastic member 69. It should be noted that the screw 45 and the nut 23 constitute an irreversible connection in the sense that this is provided to prevent vertical stress applied to the driven member 29 being converted by the screw and the nut into a rotational movement of the driving member 21. Therefore, it is not necessary to permanently maintain a power supply to the stator and rotor in order to lock the control member 9 at its current position. Each drive mechanism 11 further comprises a guide in the form of a device 71 for guiding the driven member 29 in translation and blocking it in rotation relative to the stator 17. Typically, this device 71 comprises one or more slides 73 for orientation parallel to the center axis C, wherein each slide 73 interacts with a key 74 that is integral with the driven member 23. This device thus makes it possible to prevent the rotation of the driven member 29 when the driving member 21 is rotated by the rotor 19. Each drive mechanism 11 further comprises an upper frame 75 on which are mounted the motor 15 and the blocking device 31, and a lower frame 77 on which is mounted the device 71 for guiding in translation and blocking in rotation. The lower frame 77 only carries the device 75 for guiding in translation and blocking in rotation. It may therefore be added in order to facilitate the circulation of the primary liquid. This contributes to reducing the pressure drop and to facilitating the cooling of the motor 15 and the electromagnetic coils 63. The upper frame 75 and the lower frame 77 are fixed to each other so that the lower frame 77 is closer to the core 7 than the upper frame 75. In fact, the electrical parts, for example the motor, the electromagnetic coils, the electrical connections and the instrumentation are sensitive to nuclear radiation. It is therefore advantageous to locate them remote from the core 7. The lower frame only carries robust mechanical members, and may therefore be advantageously arranged closer to the core 7. Furthermore, the upper frame 75 and the lower frame 77 are rigidly fixed to each other by removable fasteners. This has the effect of facilitating the maintenance of the drive mechanism 11. The upper frame, which carries the most compact and most fragile elements, may be removed from the vessel independently of the lower frame, and a block. It should be noted that the driving member 21 is disassembled separately from the upper frame and the lower frame. The driven member 29 is disassembled with the lower frame. The operation of the nuclear reactor will now be described. We consider here a starting configuration in which the driving member 21 is locked in translation parallel to the center axis C relative to the rotor 19 by the blocking device 31. This position is called the extreme high position. In this situation, the electromagnetic coil 63 is activated, so that the polar mass(es) 11 is/are held electromagnetically against the stops provided for this purpose. In the representation of FIG. 2, they are thus attracted upwards. To move a core reactivity control member 9 downwards or upwards, the stator 17 is activated and rotates the rotor 19. The rotational movement of the rotor 19 is transmitted to the driving member 21 by the connecting device 25, or, more precisely, by the rotary torque application member 27. The rotary elements 51 bear against the sides 53 of the connecting part 37, and transmit the rotary torque of the rotor to the driving member 21. According to the direction of rotation of the rotor 19, this rotation is converted into a translational movement of the driven part either upwards or downwards and parallel to the center axis C. In fact, the screw 23 is rotated so that the nut 45 moves in translation along the screw. This causes a displacement of the whole driven member 29, which itself drives the control member 9 in translation parallel to the center axis C. This movement is guided by the guide device 71, wherein the keys 74 slide in slides 73 provided for this purpose. If it is necessary to rapidly lower the core reactivity control members 9 into the inside the nuclear fuel assemblies, for example in an emergency, the power supply of the electromagnetic coil 63 may be cut off. The polar mass(es) 61 is/are no longer electromagnetically held against their stop, but are biased in a direction leading to the retraction of the blocking members 33 by the elastic members provided for this purpose. In this situation, the driving member 21 is no longer blocked in translation relative to the rotor 19. The elastic member 69 urges the driving member 21 towards the core 7, wherein the latter in turn drives the driven member 29 by the bias of the screw-nut torque. The driving member 21 and the driven member 29 thus move together in translation relative to the rotor 19. The connecting part 37 of the driving member 21 moves inside the passage 35. The stroke in translation of the driving member 21 and the driven member 29 depends on the position of the nut 45 along the screw 23 when the power supply of the coil 63 is cut off. This stroke is maximum when the nut 45 is raised to the maximum along the screw 23, as shown in FIG. 2. The driving member 21 and the driven member 29 then move to an extreme low position. It should be noted that both in the extreme high position and in the extreme low position, the connecting part 37 of the driving member 21 remains in engagement with the rotary torque application member 27. More specifically, in the extreme high position, a first section 79 of the connecting part 37 interacts with the rotary torque application member 27, and in the extreme low position a second section 81 of the connecting part interacts with the rotary torque application member 27. The first section 79 is located at the lower end of the connecting part 37, and therefore adjoins the shoulder 67. The second section 81 is located at the upper end of the connecting part 37. The fall time of the entire driving member/driven member is particularly short. In fact, because the screw-nut connection is released with the driving member and the driven member, the fall is a simple translational movement and not the helical movement of a screw or a nut. The mechanical friction is minimized, especially in the case where the torque application member comprises one or more rotating elements rolling along the connecting part. The hydrodynamic resistance to the falling movement is reduced by the fact that a gap of significant width is created between the rotor and the connecting part of the driving member. Moreover, this hydrodynamic residence only affects the height of the rotor, which is low compared to the height of the driving member or the driven member. Finally, the mass of the driving member and the driven member contributes to accelerate the fall. After the driving member and the driven member 29 have been released in order to bring the latter to its highest extreme position, the stator 17 is activated in order to rotate the rotor 19 in the direction that would normally move the driven member 29 towards the core, i.e. downwards. Because the driven member 29 is ultimately downwards, this results in a lifting of the driving member 21. When it is detected that the shoulder 67 has reached its initial position, the electromagnetic coil 63 is re-supplied, so that the blocking members 33 pivot and block the driving member 21 in its extreme high position. The arrival of the shoulder 67 at its initial position may be detected by any means, for example by a limit sensor. The control of the blocking device is independent of the control of the motor 15 to ensure the raising or lowering of the control member. This is particularly advantageous because the control of the electromagnetic coil 63 of the blocking device is classified at the highest level of safety, which is not the case for the motor control 15. The drive mechanism has low power consumption, and therefore low heat dissipation, in particular because the maneuvering of the control members requires very little energy, because of the gearing by the screw-nut system. Furthermore, the resetting of the blocking members is effected unloaded, which only requires a low-power electromagnetic coil. It will again be noted that the air gap between the rotor and the stator or between the polar mass(es) and the electromagnetic coil that moves them does not come into play during the release of the driving member and the driven member, nor in the maintenance of the seal in the device, nor for refrigerating the system. This gap may be reduced to a minimum, so that the electromagnetic coupling is improved and the size and power of the windings are limited. In addition, the number and volume of jacketed members is particularly small. The jacketed members are those that must be physically isolated from the primary liquid: i.e. the rotor, the stator, and the electromagnetic coil.
	abstract	The present invention relates to a laser processing method and the like having a structure for making it possible to process an object to be processed in various ways while accurately adjusting the installation state of the object. The method irradiates the object with plural adjustment laser light beams that are set in a specific positional relationship against a converging point of processing laser light beam, and adjusts the state of installation of the object while monitoring irradiation areas of the adjustment laser light beams on the surface of the object. Each irradiation directions of adjustment laser light beams is different from that of the processing laser light beam. By reflecting the irradiation condition of the adjustment laser light beam and monitored information of the irradiation areas in positional adjustment of the object, the installation state of the object can be adjusted in accordance with various kinds of processing.
	abstract	A passive safety system for a nuclear power plant (100) cools the plant after shutdown, even when primary water circulation is disabled. The system comprises a source of compressed gas (112, 805) which can be the system's only source of operating energy, a source of external cooling water (106, 500), and interconnection components. If the reactor overheats, the gas is used to force the cooling water into the reactor's core. The gas can be taken from a highly compressed source and decompressed to a lower pressure suitable for forcing the water from the source, in which case the water can first be used to supply heat to the expanding gas to prevent it from freezing its environment. The system can be located underground or can be portable, e.g., carried on railroad cars or other wheeled conveyances. The system can be located above ground, or in a covered trench (705).
	claims	1. A metal fuel pin system for a nuclear reactor, the system comprising:an annular metal nuclear fuel alloy, wherein a central hole provides for an effective fuel density of 75% or less upon irradiation;a zirconium sheath surrounding and fit tightly to the metal nuclear fuel alloy;a cladding surrounding the sheath; anda gas plenum. 2. The system of claim 1, wherein the metal nuclear fuel alloy comprises uranium-zirconium. 3. The system of claim 1, wherein the metal nuclear fuel alloy comprises uranium-molybdenum. 4. The system of claim 1, wherein the metal nuclear fuel alloy comprises transuranic elements. 5. The system of claim 1, wherein the metal nuclear fuel alloy comprises thorium alloys. 6. The system of claim 1, wherein the gas plenum is filled with helium. 7. The system of claim 1, wherein the cladding is steel. 8. The system of claim 1, wherein the metal nuclear fuel alloy acts like a traditional metal fuel upon irradiation. 9. The system of claim 1, wherein the metal nuclear fuel alloy is cast into the zirconium sheath to form a unitary product. 10. A metal fuel mold system comprising:a mold block with a cylindrical hole for receiving metal nuclear fuel alloy;a central rod within the cylindrical hole; anda zirconium sheath lining the cylindrical hole. 11. The system of claim 10, wherein the mold block comprises graphite. 12. The system of claim 10, wherein the central rod comprises steel coated with titanium nitride or a threaded solid graphite rod. 13. The system of claim 10, wherein the metal nuclear fuel alloy comprises uranium-zirconium. 14. The system of claim 10, wherein the metal nuclear fuel alloy comprises uranium-molybdenum. 15. The system of claim 10, wherein the metal nuclear fuel alloy further comprises transuranic elements. 16. The system of claim 10, wherein the metal nuclear fuel alloy comprises thorium alloys. 17. The system of claim 10, wherein the system is adapted for bottom pour casting. 18. A method of fabricating a sheathed, annular metal nuclear fuel, the method comprising:bottom pouring a liquid metal nuclear fuel alloy into a mold, wherein the mold comprises a set of holes within the mold, a rod in the approximate center of each of the holes, and a zirconium sheath within each of the one or more holes;allowing the liquid metal nuclear fuel alloy to form a sheathed, annular metal fuel;removing the sheathed, annular metal fuel; andplacing the sheathed, annular metal fuel in a cladding with a gas plenum. 19. The method of claim 18, wherein the one or more tubes are placed into a cladding prior to bottom pouring. 20. The method of claim 18, wherein the rod is a titanium nitride coated steel rod or a threaded solid graphite rod. 21. The method of claim 18, wherein the metal nuclear fuel alloy comprises uranium-zirconium. 22. The method of claim 18, wherein the metal nuclear fuel alloy comprises uranium-molybdenum. 23. The method of claim 18, wherein the metal nuclear fuel alloy comprises transuranic elements. 24. The method of claim 18, wherein the metal nuclear fuel alloy comprises thorium alloys. 25. The method of claim 18, further comprising remote fabrication of reprocessed fuel. 26. A method of using an annular metal fuel slug, the method comprising:providing an annular metal fuel slug created by bottom pour casting;initially irradiating of the annular metal fuel slug; andwherein the annular metal fuel slug acts like a traditional metal fuel after initial irradiation. 27. The method of claim 26, further comprising remote fabrication of reprocessed fuel. 28. The method of claim 26, further comprising removing minor actinides from spent fuel and alloying the minor actinides with new metal fuel. 29. The method of claim 26, further comprising providing a zirconium sheath surrounding the annular metal fuel slug. 30. The method of claim 26, wherein the annular metal fuel slug comprises thorium alloys.
	summary
	summary
	abstract	Embodiments of an apparatus and methods for correcting systematic non-uniformities using a gas cluster ion beam are generally described herein. Other embodiments may be described and claimed.
047298677	description	DETAILED DESCRIPTION OF THE INVENTION In the following description, like reference characters designate like or corresponding parts throughout the several views of the drawings. Also in the following description, it is to be understood that such terms as "forward", "rearward", "left", "right", "upwardly", "downwardly", and the like are words of convenience and are not to be construed as limiting terms. In General Referring now to the drawings, and particularly to FIGS. 1 to 3, there is shown a nuclear fuel assembly, generally designated 10 for a boiling water nuclear power reactor (BWR), with which the spring retainer apparatus (FIGS. 11 to 17) of the present invention can be employed, as will be described later on. The fuel assembly 10 includes an elongated outer tubular flow channel 12 that extends along substantially the entire length of the fuel assembly 10 and interconnects an upper support fixture of top nozzle 14 with a lower base or bottom nozzle 16. The bottom nozzle 16 which serves as an inlet for coolant flow into the outer channel 12 of the fuel assembly 10 includes a plurality of legs 18 for guiding the bottom nozzle 16 and the fuel assembly 10 into a reactor core support plate (not shown) or into fuel storage racks, for example, in a spent fuel pool. The outer flow channel 12 generally of rectangular cross-section is made up of four interconnected vertical walls 20 each being displaced about ninety degrees one from the next. Formed in a spaced apart relationship in, and extending in a vertical row at a central location along, the inner surface of each wall 20 of the outer flow channel 12, is a plurality of structural ribs 22. The outer flow channel 12, and thus the ribs 22 formed therein, are preferably formed from a metal material, such as an alloy of zirconium, commonly referred to as Zircaloy. Above the upper ends of the structural ribs 22, a plurality of upwardly-extending attachment studs 24 fixed on the walls 20 of the outer flow channel 12 are used to interconnect the top nozzle 14 to the channel 12. For improving neutron moderation and economy, a hollow water cross, as seen in FIGS. 1, 2 and 4 and generally designated 26, extends axially through the outer channel 12 so as to provide an open inner channel 28 for subcooled moderator flow through the fuel assembly 10 and to divide the fuel assembly into four, separate, elongated compartments 30. The water cross 26 has a plurality of four radial panels 32 composed by a plurality of four, elongated, generally L-shaped, metal angles or sheet members 34 that extend generally along the entire length of the channel 12. The sheet members 34 of each panel 32 are interconnected and spaced apart by a series of elements in the form of dimples 36 formed therein and extending therebetween. The dimples 36 are provided in opposing pairs that contact each other along the lengths of the sheet members 34 to maintain the facing portions of the members in a proper spaced-apart relationship. The pairs of contacting dimples 36 are connected together such as by welding to ensure that the spacing between the sheet members 34 forming the panels 32 of the central water cross 26 is accurately maintained. The hollow water cross 26 is mounted to the angularly-displaced walls 20 of the outer channel 12. Preferably, the outer, elongated lateral ends of the panels 32 of the water cross 26 are connected such as by welding to the structural ribs 22 along the lengths thereof in order to securely retain the water cross 26 in its desired central position within the fuel assembly 10. Further, the inner ends of the panels together with the outer ends thereof define the inner central cruciform channel 28 which extends the axial length of the hollow water cross 26. Also, the water cross 26 has a lower flow inlet end 38 and an opposite upper flow outlet end 40 which each communicates with the inner channel 28 for providing subcoolant flow therethrough. Disposed within the channel 12 us a bundle of fuel rods 42 which, in the illustrated embodiment, number sixty-four and form an 8.times.8 array. The fuel rod bundle is, in turn, separated into four mini-bundles thereof by the water cross 26. The fuel rods 42 of each mini-bundle, such being sixteen in number in a 4.times.4 array, extend in laterally spaced apart relationship between an upper tie plate 44 and a lower tie plate 46. The fuel rods 42 in each mini-bundle are connected to the upper and lower tie plates 44,46 and together therewith comprise a separate fuel rod subassembly 48 within each of the compartments 30 of the channel 12. A plurality of spacers or grids 50 axially spaced along the fuel rods 42 of each fuel rod subassembly 48 are composed of interleaved inner straps 52 and an outer strap 54 which maintain the fuel rods in their laterally spaced relationships. The lower and upper tie plates 44,46 of the respective fuel rod subassemblies 48 have flow openings 56 defined therethrough for allowing the flow of the coolant fluid into and from the separate fuel rod subassemblies. Also, coolant flow paths provide flow communication between the fuel rod subassemblies 48 in the respective separate compartments 30 of the fuel assembly 10 through a plurality of openings 58 formed between each of the structural ribs 22 along the lengths thereof. Coolant flow through the openings 58 serves to equalize the hydraulic pressure between the four separate compartments 30, thereby minimizing the possibility of thermal hydrodynamic instability between the separate fuel rod subassemblies 48. Apparatus for Loading Fuel Rods into Grids In the normal manner of loading fuel rods 42 through the fuel assembly grid 50, springs 60 and dimples 62 defined by the inner straps 52 and normally extending into the hollow cells 64 formed by the interleaved straps, as seen in FIGS. 6 and 7, will rub against the fuel rod outer surfaces and cause scratching thereof. Not only is the external appearance of the fuel rods 42 adversely affected, more importantly accelerated corrosion is likely to occur at the scratch sites and debris formed by material from the scratch is released into the coolant flow through the fuel assembly 10. Referring now to FIGS. 8 to 20 in addition to FIGS. 6 and 7, in accordance with the present invention, a spring retainer apparatus, generally designated 66, is provided for facilitating the loading of the fuel rods 42 into the cells 64 of the fuel assembly grid 50 in a manner which minimizes marring or scratching of the outer surfaces of the fuel rods. It will be noted that some of the inner straps 52A are disposed in pairs so as to form the springs 60 in pairs thereof which are positioned in back-to-back relationships between adjacent ones of cells 64. The springs 60 in each pair thereof are configured to normally assume expanded positions, as seen in FIG. 6, in which they are displaced away from one another to engage the fuel rods 42 when received in the respective cells 64. However, using the apparatus 66 of the present invention, the springs 60 in each pair thereof can be deflected to retracted positions, as seen in FIGS. 8 and 10, in which they are displaced toward one another to provide the clearance necessary to allow loading of the fuel rods 42 in the respective cells 64 without engaging the springs 60. More particularly, as seen in FIGS. 8 to 17, the spring retainer apparatus 66 includes a pair of first and second spring retainer assemblies 68A, 68B which are substantially identical. Each of the spring retainer assemblies 68A, 68B includes a pair of elongated holder bars 70 and a handle bar 72 interconnecting the holder bars together at the same one of the opposite ends thereof so that the holder bars 70 are concurrently extended along and aligned with a pair of the straps 52A of the grid 50 which define the pairs of springs 60. The sizes of the cross-sectional dimensions of the holder bars 70 are designed to allow the bars to be extended between and spaced from positions occupied by fuel rods 42 when received in the cells 64 of the grid 50 so that neither the bars 70 nor the springs 60 held in retracted positions by the assemblies 68 will engage nor interfere with the fuel rods 42 during loading thereof. In addition, each of the holder bars 70 of the spring retainer assemblies 68A, 68B supports a number of depending members 74. The number of such members 74 corresponds to the number of pairs of springs 60 defined by the pair of straps 52A aligned with the specific holder bar 70. In the illustrated embodiment, both the members 74 on each bar 70 and the springs 60 aligned with each bar are four in number. Each of the depending members 74 has a terminal end 76 configured to engage and retain the springs 60 of one pair thereof in their retracted positions when the respective holder bar 70 supporting the member 74 is aligned with and moved toward the pair of straps 52A aligned with the holder bar 70. Preferably, each of the members 74 supported by a respective one holder bar 70 is rigidly connected to and extends from the bar in a generally parallel relationship with respect to the other members 74 supported by the bar. Further, each member 74 is an elongated post with the terminal end 76 of the member being a bifurcated end on the post. The bifurcated end 76 on each of the posts 74 defines two spaced pairs of spaced apart fingers 78,80 adapted to receive the pair of springs 60 therebetween and engage the spring pair at two displaced locations therealong, as depicted in FIG. 10, for retaining them in their retracted positions. Many configurations are possible for defining the bifurcated ends 76 of the posts 74, the configurations seen in FIGS. 19 and 20 being merely one example. The important feature, whatever the particular configuration or structure of the fingers 78,80 might be, is that the bifurcated terminal end of each post 74 should define a pocket 82 adapted to receive the pair of springs 60 therein and retain the springs in their retracted positions, as represented in FIG. 20, and a convergently-tapered entrance 84 to the pocket 82 for facilitating insertion of the springs 60 when in their retracted positions into the pocket. In the preferred embodiment seen in FIGS. 19 and 20, the tapered entrance 84 is of sufficient size (i.e., length and width) to cause deflection of the springs 60 from their normal expanded positions to their retracted positions, both of which are depicted in FIG. 20, as the post 74 is moved toward and into contact with the springs 60 at its bifurcated end 76. However, in an alternative embodiment seen in FIG. 22, the tapered entrance 84' to the pocket 82' defined on each post 74' is insufficient in size to cause such deflection of the springs 60. So here, a fixture 86 of dummy fuel rods is first inserted into the cells 64 of the grid 50 to deflect the springs 60 to their retracted positions and then bifurcated terminal ends 76' of the posts 74' are inserted on the retracted springs to retain them in such positions. Finally, the holder bars 70 of the respective first and second spring retainer assemblies 68A, 68B have mating means permitting the assemblies to be superimposed one on top of the other, as seen in FIGS. 8 to 11, in criss-cross fashion and interconnected in alignment with all of the pairs of the springs 60 defined by the straps 52A of the grid 50. Particularly, the mating means on the holder bars 70 are in the form of aligned notches 88,90 defined in the respective holder bars. It will be noted that the notches 88 of the assembly 68A open downwardly, whereas the notches 90 of assembly 68B open upwardly. It will be observed that some of the posts 74 on the holder bars 70 are slightly larger than other of the posts. This is because the sets of the four radial springs 60 in the different quadrants of the grid 50, as seen in FIGS. 7 and 9, are disposed at different levels within the grid due to the manner in which the springs 60 are attached to other of the inner straps 52 which define the dimples 62. It is thought that the invention and many of its attendant advantages will be understood from the foregoing description and it will be apparent that various changes may be made in the form, construction and arrangement thereof without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the form hereinbefore described being merely a preferred or exemplary embodiment thereof.
	description	This is a National Stage application of PCT international application PCT/FR2017/051646, filed on Jun. 21, 2017, which claims the priority of French Patent Application No. 16 55871, filed Jun. 23, 2016, both of which are incorporated herein by reference in their entirety. The present invention relates to a process for dissolving nuclear fuel, this process having improved performance compared with current dissolution processes, in particular when the nuclear fuel, whether irradiated in a nuclear reactor or a fabrication reject, comprises plutonium or a mixture of uranium and plutonium. The present invention also relates to the use of a particular device to implement this dissolution process. Finally, the invention relates to a process for dissolving irradiated nuclear fuel which implements the preceding dissolution process, to obtain improved dissolution of valuable compounds contained in the dissolution fines from current dissolution processes. With the constant search to optimize management of radioactive waste, the fuel unloaded from nuclear reactors, called “irradiated fuel” or “spent fuel”, is treated for the purpose of separating recyclable material such as uranium and plutonium from ultimate waste currently considered to be non-recyclable, i.e. fission products such as platinoids and minor actinides, e.g. neptunium, americium and curium. Treatment entails a set of physical and chemical processes: the assemblies of irradiated nuclear fuel, composed of sealed claddings inside which the material forming the nuclear fuel is confined, are typically cut into segments having a length of about 3 cm to 5 cm. These segments are then immersed in a concentrated nitric acid solution to dissolve the nuclear material confined within the claddings, these claddings being practically insoluble. The nitric dissolution solution obtained after this immersion contains, in the liquid phase, uranium, plutonium, minor actinides, soluble fission products and insoluble solid products among which the insoluble fission products routinely called “dissolution fines”. These dissolution fines correspond to solids of small particle size, typically less than 1 μm, resulting from the non-dissolving, with current dissolution processes, of some fission products such as platinoids and/or from partial dissolution of some others such as molybdenum, zirconium or technetium. This nitric dissolution solution is then subjected to a succession of chemical steps to separate the valuable and/or recyclable materials and to produce solutions of plutonium and uranium from which the uranium and plutonium are recycled to produce fresh fuel. The process of dissolving nuclear fuel in a nitric acid solution amounts to a key step in treatment since it must allow the fullest possible passing into solution of the chemical elements contained in this nuclear fuel. To date, this nuclear fuel dissolution process is a process able to be carried out in batch or continuous operation. With continuous operation, the dissolution process is implemented by means of a rotating dissolver comprising a bucket wheel rotating in a tank containing the nitric acid solution heated to between 90° C. and 105° C. The buckets are loaded when the wheel is at a standstill via direct feeding of the segmented assemblies into a bucket. The wheel is then rotated to feed the next bucket. The rotating speed of the wheel is chosen so as to guarantee a residence time of the immersed segmented assemblies that is longer than two hours, to optimize dissolution of the irradiated fuel in the nitric acid solution. The performance level of this current dissolution process varies as a function of the constituent material of the nuclear fuel that it is sought to dissolve. While the current process using said rotating dissolver is fully satisfactory for the dissolution of uranium-based nuclear fuel, in particular containing uranium oxides known as “UOX fuels”, it is observed that this is not necessarily the case for all uranium and plutonium nuclear fuels, in particular for fuels containing mixed oxides of uranium and plutonium called “MOX fuels”. Some of these MOX fuels, whether or not irradiated, can contain greater or lesser amounts of chemical heterogeneities in the form of islands and characterized by a higher plutonium content than in the remainder of the fuel. In particular, when the plutonium content in an island reaches about 35% of the total uranium and plutonium content, the fraction of insoluble plutonium in the nitric acid starts to increase and reaches 100% when the plutonium content, relative to the total uranium and plutonium content, is in the region of 60% and 70% in 5 M and 10 M nitric acid respectively. In an attempt to overcome this dissolution issue encountered with MOX fuels having high local contents of plutonium, it has been proposed to place under agitation the mixture formed by the segments of nuclear fuel and the nitric acid solution. However, it is difficult to envisage the implementing of mechanical agitation within a rotating dissolver. Therefore, and if the dissolution process is carried out in a rotating dissolver, it has been proposed to continuously renew the nitric acid solution, the buckets being pierced to allow the circulation of this solution. However, said proposition is not without impact on the volumes of nitric acid solution to be employed. Also, in current dissolution processes, the dissolution fines contained in the nitric dissolution solution can be subjected to a solid/liquid separation operation, e.g. via centrifugation, and then treated by integration into the flow of material to be vitrified in the vitrification process. Yet, since these dissolution fines are associated with, or integrate within their particles, compounds that are recoverable such as plutonium, uranium and/or soluble fission products, it is desirable to find means to recover these valuable compounds by optimizing the dissolution thereof in the nitric acid solution so that they can be recycled for the fabrication of fresh fuel. In the remainder of the present description, these recoverable compounds associated with the dissolution fines or integrated in the particles of these dissolution fines are designated as being “contained” in these dissolution fines. It is therefore the objective of the invention to overcome these different shortcomings just mentioned of the dissolution processes currently used to treat nuclear fuel, whether or not irradiated, and therefore to propose a process allowing improved dissolution of this fuel, in particular improved dissolution of MOX fuels having high local contents of plutonium. It is also an objective of the invention to provide a process for dissolving irradiated nuclear fuel allowing optimized dissolution of the recoverable compounds contained in the dissolution fines resulting from current dissolution processes, with a view to recycling said compounds. It is a further objective of the invention to provide a dissolution process able to be implemented in batch or continuous operation and allowing improved dissolution of any type of irradiated nuclear fuel that is to be treated, using reasonable volumes of nitric acid solution and under optimum safety conditions. In particular, it must be possible for this dissolution process to be implemented independently of the composition of the irradiated nuclear fuel, whether it is irradiated fuel which originally was fresh fuel of UOX type or MOX type, and irrespective of the plutonium content in any islands which may be contained in this MOX fuel compared with the total uranium and plutonium content. In addition, the fabrication of fresh plutonium-containing nuclear fuel can lead to the generation of fabrication rejects. Said fabrication rejects can be formed in particular by plutonium mixed oxide powders possibly containing americium, by uranium and plutonium mixed oxide powders (U,Pu)O2 and/or by pellets of mixed fuel of MOX type, these powders and/or pellets being considered non-conforming to specifications and may also be confined in sheaths called “rods”. It is known that these non-irradiated materials exhibit more refractory behaviour on dissolution by nitric acid than these same materials when present in irradiated fuel. More generally, this process must therefore also allow the dissolution of these fabrication rejects and materials included in the composition of fresh (non-irradiated) fuel, such as plutonium oxide powders or uranium and plutonium mixed oxide powders, pellets of MOX fuel or rods of fresh MOX fuel, with a view to recycling the recyclable materials contained in these various fabrication rejects. These objectives and others are reached first with a process for dissolving nuclear fuel, whether irradiated or fresh, comprising the immersing of the nuclear fuel in a nitric acid solution. According to the invention, this dissolution process also comprises mechanical milling of the nuclear fuel, this mechanical milling being performed in the nitric acid solution during said immersion. The process of the invention therefore entails concomitant implementing of immersion and mechanical milling of the nuclear fuel, to optimize the dissolution of the constituent materials of this fuel in a nitric acid solution and thereby to obtain a nitric dissolution solution having a liquid phase which not only comprises the compounds that are at least partly dissolved with current dissolution processes, and in particular plutonium and optionally uranium, minor actinides and soluble fission products, but also the recoverable compounds contained in the dissolution fines which current dissolution processes are unable to solubilize such as plutonium, uranium and/or soluble fission products. The application of said mechanical milling during immersion of the nuclear fuel allows a gradual decrease in the size of the particles, or grains, of the nuclear fuel to be dissolved, and hence a gradual increase in specific surface area. By doing so, the mechanical milling associated with immersion allows an increase, on the surface of the nuclear fuel particles, in the number of reaction sites at which the dissolution reaction takes place, but also in the number of structural and/or crystallographic defects which correspond to potential corrosion sites and hence potential dissolution sites of said nuclear fuel particles in the nitric acid solution. All the above-described phenomena allow the consideration that the dissolution process of the invention is a process which allows the obtaining of continuous activation of the surface of the nuclear fuel particles, promoting dissolution thereof in the nitric acid solution. The performing of mechanical milling during immersion of the nuclear fuel also ensures renewal via agitation of the nitric acid solution at the solid/liquid interface (nuclear fuel particles/nitric acid solution), without the need to have recourse to excessive volumes of nitric acid solution and/or to an additional agitation system as such. The implementation of the dissolution process of the invention can therefore be fully envisaged for batch or continuous operation. This finding is all the more unexpected and surprising as the performance levels of dissolution reached with the process of the invention are much higher than those which would be obtained with a nuclear fuel dissolution process providing for milling prior to immersion and wherein the specific surface area of the nuclear fuel would undeniably be higher, and that right at the start of immersion. In addition, by performing mechanical milling in the nitric acid solution, the process of the invention has the other major advantage of limiting dissemination of the ground particles of nuclear fuel and therefore any resulting contamination, compared with a dissolution process in which this mechanical milling is “dry” milling prior to immersion of the fuel in the nitric acid solution, having regard to the nuclear nature of the fuel to be dissolved. In one advantageous variant of the process of the invention, the nitric acid solution in which the nuclear fuel is simultaneously immersed and milled is heated to between 90° C. and 105° C. The fact that the nitric acid solution is heated allows an increase in the dissolution kinetics of the nuclear fuel and, therefore, a further improvement in the dissolution performance of the process of the invention. In one variant of the process of the invention, the molar concentration of the nitric acid solution can be between 1 mol/L and 10 mol/L. The molar concentration of the nitric acid solution can be adapted in particular to the composition of the material forming the nuclear fuel to be dissolved. The molar concentration of the nitric acid solution is advantageously between 3 mol/L and 8 mol/L. In another advantageous variant of the process of the invention, the nitric acid solution may also comprise a neutron poison. The presence of a neutron poison in the mixture formed by the nuclear fuel and nitric acid solution allows optimization of the condition of a neutron state of this mixture, called sub-critical. As an example of neutron poison, mention can be made of gadolinium. In another variant of the process of the invention, the immersing of the nuclear fuel in the nitric acid solution can be maintained for a time of at least 30 min. The immersion time of the nuclear fuel in the nitric acid solution can be adapted in particular to the composition of this nuclear fuel to be dissolved. With the process of the invention, in-line monitoring of dissolution can be ensured, allowing piloted halting of dissolution, and hence draining of the dissolution reactor, as a function of the state of progress of the dissolution reactions under consideration. As indicated above, unlike prior art dissolution processes, the process of the invention comprises mechanical milling of the nuclear fuel that is carried out in the nitric acid solution during the immersion of said nuclear fuel. Evidently, this mechanical milling can be carried out during part of the immersion time of the nuclear fuel. However, in one particularly preferred variant of the process of the invention, mechanical milling is carried out during the entire immersion time so as to further optimize dissolution of the nuclear fuel in the nitric acid solution. If the nuclear fuel is confined within a cladding, the dissolution process of the invention can advantageously further comprise a step to de-clad the nuclear fuel, this decladding step being performed prior to immersion. Said decladding step promotes contact between the nitric acid solution and the consituent material of the nuclear fuel, whether this material is in powder or in pellet form. This decladding step is conventionally ensured by mechanical decladding. Said mechanical decladding step can be performed for example by shearing or with the technical means proposed in document EP 2 345 041 allowing these claddings to be emptied by “ovalisation”. Evidently, if the constituent material of the nuclear fuel is a non-irradiated plutonium oxide powder, possibly also containing uranium or americium, or a non-irradiated pellet (rejected on fabrication) containing plutonium oxide or a mixed uranium and plutonium oxide, the dissolution process of the invention does not require said prior decladding step, the non-irradiated powders and pellets being able to be milled directly. The nuclear fuel to be dissolved, whether irradiated or non-irradiated, may comprise at least one plutonium oxide and/or at least one mixed oxide of plutonium and of at least one second metal other than plutonium. As will be seen below, this second metal can particularly be selected from among uranium, thorium, neptunium, americium and curium. When the nuclear fuel to be dissolved is an irradiated fuel, this fuel can evidently come from fresh fuel comprising at least one uranium oxide such as an uranium dioxide UO2 fuel, also called UOX fuel. If it comprises at least one mixed oxide of plutonium and of at least one second metal, this nuclear fuel, whether or not irradiated, can be a fuel of a mixed oxide of plutonium and of at least one element selected from among uranium, thorium and a minor actinide. By “minor actinide” is meant a chemical element in the actinide family with the exception of uranium, plutonium and thorium. Said minor actinides are formed in the reactors by successive capturing of neutrons by the uranium nuclei of the nuclear fuel. The chief minor actinides are neptunium, americium and curium. The nuclear fuel comprising at least one mixed oxide of plutonium and of at least one second metal can particularly be a mixed oxide fuel of uranium and plutonium (U,Pu)O2, also called MOX fuel. With its improved dissolution properties compared with current dissolution processes, the process of the invention particularly allows the dissolution of MOX fuels having local chemical heterogeneities with high plutonium content, typically 35% or more of the total uranium and plutonium content. The fuel comprising at least one mixed oxide of plutonium and of at least one second metal may also be a mixed oxide fuel of plutonium and of one or more minor actinides, this or these minor actinides more particularly being selected from among neptunium, americium and curium. Although the process of the invention focuses essentially on the dissolution of nuclear fuel formed of an irradiated nuclear fuel, it can also advantageously be applied to the dissolution of fresh, non-irradiated nuclear fuel for which dissolution in a nitric acid solution is known to be more difficult than for the same fuel when irradiated. In particular, this nuclear fuel may comprise and even consist of fabrication rejects of non-irradiated or fresh nuclear fuel. Therefore, the nuclear fuel that can be dissolved with the process of the invention can be irradiated fuel and/or non-irradiated fuel. The invention secondly relates to the use of a particular device to implement the process for dissolving a nuclear fuel such as defined above, the advantageous characteristics of the dissolution process possibly being taken alone or in combination. According to the invention, this device is a mill equipped with mechanical milling means. As is fully conventional, said mill is equipped with a milling chamber equipped with mechanical milling means and fed with the nuclear fuel, nitric acid solution and optional neutron poison. The advantage of the use of said mill particularly lies in the fact that it can be easily and safely connected with means for feeding the nuclear fuel and nitric acid solution for loading thereof into the milling chamber, with means for evacuating the nitric dissolution solution, solid insoluble products and gases, and with one or more of the following means: means for filtering the nitric dissolution solution; heating means; means for recirculating the nitric dissolution solution; sampling means; and means for adjusting dissolution reaction parameters such as temperature and pH. As examples, the heating means can be adapted for direct heating of the mixture formed by the nuclear fuel and nitric acid solution, or they can be associated with means for circulating said mixture such as an expansion tank. Similarly, adjustment of pH can be obtained by adding a suitable solution either directly to the milling chamber or via an expansion tank in which there circulates the mixture formed by the nuclear fuel and nitric acid solution. The connecting of the mill to the sampling means can notably allow monitoring of the state of progress of dissolution. Said sampling means can be arranged, in series or in parallel, to measure the pH of the nitric dissolution solution and/or the concentration of ions in this solution (e.g. via colorimetry/UV/visible spectrometry, via assay) or to determine the particle size distribution of the nuclear fuel to be dissolved (e.g. granulometry). Said sampling means can be composed in particular of milli-fluid cells. The mill used to implement the dissolution process of the invention is advantageously a bead or pebble mill. The mill materials and the beads or pebbles are evidently adapted to resist the nuclear nature of the fuel to be dissolved and any corrosion which could be generated by the nitric acid solution. Therefore, and in one advantageous version of the invention, the bead(s) and other pebble(s) are in zirconium dioxide, also known as zirconia, which optimizes resistance to corrosion generated by the mixture formed by the nuclear fuel and nitric acid solution. The invention thirdly relates to a process for dissolving irradiated nuclear fuel allowing improved dissolution of recoverable compounds contained in the dissolution fines from current dissolution processes. According to the invention, this process comprises the following successive steps taken in this order: (a) dissolving irradiated nuclear fuel by immersion in a nitric acid solution, after which a nitric dissolution solution containing dissolution fines is obtained; (b) separating the dissolution fines from the nitric dissolution solution; and (c) dissolving the dissolution fines separated at step (b) by implementing the previously described dissolution process, the advantageous characteristics of this process possibly being taken alone or in combination. In other words, the process for dissolving irradiated nuclear fuel comprises the following successive steps taken in this order: (a) dissolving irradiated nuclear fuel by immersion in a nitric acid solution, after which a nitric dissolution solution containing dissolution fines is obtained; (b) separating the dissolution fines from the nitric dissolution solution; and (c) dissolving the dissolution fines separated at step (b) by immersion and mechanical milling of these dissolution fines in a nitric acid solution, this mechanical milling being performed in the nitric acid solution during said immersion. Steps (a) and (b) of the above process correspond to the steps of current dissolution processes, these steps having been described in the foregoing under the chapter titled “State of the prior art”. As indicated in this chapter, the implementation of these steps (a) then (b) do not allow satisfactory dissolution of the recoverable compounds contained in dissolution fines, in particular plutonium, uranium and/or soluble fission products. However, the performing of step (c) after step (b) allows optimization of this dissolution of the recoverable compounds contained in the dissolution fines from current dissolution processes, with a view to recycling thereof. The flow of solid materials that can be vitrified is thereby de facto depleted of plutonium, of uranium and/or of soluble fission products. In one variant of the process of the invention, when the irradiated nuclear fuel is confined in a cladding, a step to de-clad the irradiated nuclear fuel can be carried out, this decladding step preceding step (a). The irradiated nuclear fuel to be dissolved may comprise at least one plutonium oxide and/or at least one mixed oxide of plutonium and at least one second metal other than plutonium. This second metal can more particularly be selected from among uranium, thorium, neptunium, americium and curium. The irradiated nuclear fuel containing at least one mixed oxide of plutonium and of at least one second metal can more particularly be a MOX fuel. Other characteristics and advantages of the invention will become apparent on reading the remainder of the description referring to appended FIG. 1 and relating to examples of embodiment of dissolution processes, two processes conforming to the invention comprising simultaneous immersion and milling (Pi and PI) and two other reference processes, one only comprising immersion (Pr) and the other comprising milling followed by immersion (PR). It is specified that examples described below were conducted with cerium dioxide CeO2, sometimes called ceria, which is a non-radioactive metal oxide simulating plutonium in terms of dissolution in a nitric acid solution. These examples are evidently given to illustrate the subject of the invention and under no circumstances limit this subject-matter. In this example, a bead mill available from Wma-Getzmann under the trade name Dispermat® SL5 having a 50 mL milling chamber volume and zirconium dioxide beads were used. A three-way valve was connected to the outlet pipe of this mill for sampling purposes to determine the state of progress of ceria dissolution in the nitric acid solution by monitoring the concentration of cerium [Ce] in the resulting nitric dissolution solution, this concentration being determined by Inductively Coupled Plasma, Atomic Emission Spectrometry (ICP-AES). For the first test, 20 g of ceria were immersed in 100 mL of nitric acid solution at a molar concentration of 5 mol/L (5 M) in the milling chamber of the bead mill, in the presence of the beads, so as to monitor the progress of ceria dissolution when implementing a reference dissolution process denoted Pi. For a second test, 20 g of ceria were immersed in 100 mL of nitric acid solution at a molar concentration of 5 mol/L (or 5 M) in the milling chamber of the bead mill, but in the absence of said beads, so as to monitor the progress of ceria dissolution when implementing a reference dissolution process denoted Pr. With reference to FIG. 1 giving the change, as a function of time, in the weight concentration of cerium in each of the nitric dissolution solutions obtained when implementing the dissolution processes Pi and Pr, it is observed that: after 400 min (i.e. a little more than 6 h), the weight concentration of cerium in the nitric dissolution solution is 0.09 g/L for process Pr against 4.22 g/L for process Pi, which corresponds to 0.1% dissolution of ceria with process Pr against 5% with process Pi; and after 1350 min (about 22 h), the weight concentration of cerium in the nitric dissolution solution is 0.31 g/L for process Pr against 17.75 g/L for process Pi, which corresponds to only 0.2% dissolution of ceria with process Pr against 11% with process Pi. In other words, it is observed an increase by a factor of 50 in the dissolution kinetics of ceria in 5 M nitric acid solution, justifying the advantage of simultaneously performing ceria immersion and milling. In this example, an oscillating mill was used comprising two compartments denoted CI and CR. In compartment CI, comprising a grinding bead in zirconium dioxide, a dissolution process conforming to the invention was implemented, denoted PI. 2 g of ceria were immersed in 10 mL of nitric acid solution at a molar concentration of 5 M. After an immersion time and simultaneous milling of 7.5 h of the ceria in the nitric acid solution, the nitric dissolution solution obtained denoted SI was analysed by ICP-AES. In compartment CR, comprising a grinding bead in zirconium dioxide, a reference dissolution process was implemented, denoted PR. 2 g of ceria were immersed in 10 mL of deionized water. After an immersion time and simultaneous milling of 7.5 h of the ceria in the deionized water, the solution comprising the milled ceria was filtered and dried. The milled, dried ceria was then placed in a beaker and immersed in 10 mL of nitric acid solution at a molar concentration of 5 M, under agitation with a magnetic stir bar. After an immersion time of 7.5 h with agitation of the milled ceria in the nitric acid solution, the nitric dissolution solution obtained denoted SR was also analysed by ICP-AES. The weight concentrations of cerium measured in solutions SI and SR respectively were 4 g/L and 0.75 g/L. An increase is therefore observed in this example by a factor of 5 in the dissolution kinetics of ceria in the 5 M nitric acid solution. Such results clearly evidence the synergy of the dissolution process conforming to the invention which applies simultaneous immersion and milling, compared with a dissolution process applying milling followed by immersion. EP 2 345 041 A1
	description	The present invention relates to a core of a boiling water reactor, and particularly to a core of a boiling water reactor before decommissioning. In a boiling water reactor, a plurality of fuel assemblies are arranged and loaded in a square lattice shape in a core provided in a reactor pressure vessel. The fuel assemblies loaded into the core reside in the core for a predetermined period, are taken out of the reactor after reaching a predetermined burnup degree, and are exchanged for new fuel assemblies. In the core of the related art, it is common to operate the core by a fuel assembly having the maximum number of residence cycles in the core being loaded into the outermost periphery of the core and fuel assemblies having different numbers of residence cycles in the core by including a new fuel assembly and the fuel assembly with the maximum number of residence cycles in the core are dispersedly loaded into an inside of the outermost periphery of the core. In a method for operating the boiling water reactor of the core of the related art, in a case where the boiling water reactor is decommissioned, a fuel assembly newly loaded during fuel exchange before the decommissioning has a problem that fuel cost to power generation amount is increased by a large amount of unreacted fissile uranium of which the number of residence cycles in the core is shorter than that during normal operation being remained. For example, in PTL 1, fuel cost of a four-batch core is calculated and PTL 1 describes that the fuel cost is significantly deteriorated in three cycles before the decommissioning and, in particular, the fuel cost is twice or more in a cycle immediately before the decommissioning. Therefore, PTL 1 discloses a method for alleviating deterioration in fuel cost by loading a fuel assembly having a smaller inventory of uranium heavy metal than that of a normally used fuel assembly during the final fuel exchange immediately before the decommissioning. Specifically, in order to alleviate the deterioration in the fuel cost in the boiling water reactor before the decommissioning, a configuration in which a fuel assembly having increased the number of water rods to be disposed is loaded into the core during the final fuel exchange prior to the decommissioning is disclosed. In addition, instead of increase in the number of water rods to be disposed, a configuration in which fuel assemblies in which fuel rods not filled with fuel pellets are disposed or fuel assemblies in which fuel rods are reduced in diameter are loaded is described. PTL 1: JP-A-62-30993 Nuclear power plants are decommissioned when life thereof is finished due to the aging of equipment or the like. At this time, in the final operation cycle before decommissioning, in a case where new fuel assemblies are added and operated like the operation cycle of the related art, there is a concern about the burden of fuel cost, increase in radioactive waste, and increase in critical management risk of fuel which is taken out. However, in the configuration described in PTL 1, although since PTL 1 is configured to load new fuel assemblies with a smaller inventory of uranium heavy metal than normally used fuel assemblies, it is possible to alleviate the deterioration of the fuel cost, since the PTL 1 has a configuration in which new fuel assemblies are newly loaded into the core, it is not enough to solve the concern about burden of fuel cost, increase in radioactive waste, and increase in critical management risk due to increase in the number of fuel which is taken out. Therefore, the invention provides a core of a boiling water reactor that can be operated without loading a new fuel assembly in an operation cycle before the decommissioning. In order to solve the problem described above, according to the invention, there is provided a core of a boiling water reactor in which multiple fuel assemblies are loaded in a square lattice shape, in which, during fuel exchange, without loading fuel assemblies having a shorter loading period than a fuel assembly having the shortest loading period loaded into the core before the fuel exchange in the core after the fuel exchange, the multiple fuel assemblies are loaded so that a parameter X represented by the following equation (1) is 0.8 or more and 1.0 or less using the number of residence cycles, in the core, of fuel assemblies laterally adjacent and longitudinally adjacent to a fuel assembly having the shortest loading period and the number of residence cycles, in the core, of fuel assemblies diagonally adjacent thereto, among fuel assemblies to be loaded into the core after the fuel exchange.X=Ta/Tb (1) where, Ta: T in a case where fuel exchange is performed, Tb: T in a case where fuel exchange is not performed, T: an average value of t of fuel assembly having shortest loading period loaded into an inside-core region, t: (ΣTs+0.5×ΣTx)/(4+0.5×4), Ts: the number of residence cycles in reactor of fuel assemblies laterally and longitudinally adjacent to fuel assembly having shortest loading period in core cross section, and Tx: the number of residence cycles in reactor of fuel assemblies diagonally adjacent to fuel assembly having shortest loading period in core cross section. According to the invention, it is possible to provide a core of a boiling water reactor that can be operated without loading a new fuel assembly in an operation cycle before the decommissioning. The problems, configurations, and effects other than those described above will be clarified from description of the embodiments below. In the present specification, a boiling water reactor includes a normal boiling water reactor (BWR) that includes a recirculation pump, and uses cooling water as a moderator to flow the cooling water through outside a reactor pressure vessel and again to flow into a down comer in the core pressure vessel and an advanced boiling water reactor (ABWR) that includes an internal pump instead of the recirculation pump and circulates the coolant in the core pressure vessel. As the coolant, for example, water, pure water, heavy water, boric acid water or the like is used. In the following description, the coolant is referred to as cooling water and a case where a core according to the invention is applied to a boiling water reactor (BWR) will be described as an example. FIG. 11 is an overall schematic configuration view of a boiling water reactor (BWR) according to an embodiment of the invention. As illustrated in FIG. 11, in a boiling water reactor 10 to which a fuel disposition of fuel assemblies to be loaded into a core according to the invention to be described below is applied, a cylindrical core shroud 16 is installed in a reactor pressure vessel 11 and a core 12 in which multiple fuel assemblies are loaded is installed in the core shroud 16. In addition, a shroud head 20 that covers the core 12, a gas-water separator 18 that is attached to the shroud head 20 and also extends upward, and steam dryer 19 that is disposed above the gas-water separator 18 are provided in the core pressure vessel 11. An upper lattice plate 14 is disposed in the core shroud 16 below the shroud head 20 and is attached to the core shroud 16 and positioned at an upper end portion of the core 12. A core plate 13 is positioned at a lower end portion of the core 12, is disposed in the core shroud 16, and is installed in the core shroud 16. In addition, a plurality of fuel supports 15 are installed on the core plate 13. In addition, in the core pressure vessel 11, in order to control nuclear reaction of the fuel assemblies, a control rod guide tube 22 which enables insertion of a plurality of cross-sectional cross-shape type control rods (not illustrated) into the core 12 is provided. A control rod drive 23 is provided in a control rod drive housing (not illustrated) installed below a lower mirror 24 which is a bottom portion of the reactor pressure vessel 11 and a control rod (not illustrated) is connected to the control rod drive 23. An annular down comer 17 is formed between the cylindrical core shroud 16 and an inside surface of the reactor pressure vessel 11. A jet pump 21 is installed in the down comer 17. A recirculation system provided in the core pressure vessel 11 has a recirculation system tube 27 and a recirculation pump 28 connected to the recirculation system tube 27. Cooling water discharged from the jet pump 21 is supplied to the core 12 via a lower plenum 29. The cooling water becomes gas-liquid two-phase flow including water and steam by being heated when the cooling water passes through the core 12. The gas-water separator 18 separates the gas-liquid two-phase flow into steam and water. The separated steam in which moisture is further removed in a steam dryer 19 is guided to a main steam tube 25. This steam is led to a steam turbine (not illustrated) to rotate the steam turbine. A generator (not illustrated) connected to the steam turbine rotates to generate electric power. The steam discharged from the steam turbine is condensed in a condenser (not illustrated) to become water. This condensed water is supplied as supply water into the reactor pressure vessel 11 by a water supply tube 26. The water separated by the gas-water separator 18 and the steam dryer 19 falls and reaches an inside of the down comer 17 as cooling water. As described above, a recirculation system including the jet pump 21, the recirculation system tube 27, and the recirculation pump 28 connected to the recirculation system tube 27 forcedly circulates the cooling water into the core 12 in order to efficiently remove the heat generated in the core 12. In a method for operating the boiling water reactor (BWR) of the related art, the number of new fuel assemblies and the fuel disposition (fuel assembly loading position to core) are determined so that excess reactivity of the core becomes zero at the end of a cycle. In addition, since the amount of the burnable poison such as gadolinia (Gd) mixed in new fuel assemblies is determined so as to burn out in an operation cycle, an infinite multiplication factor of a fuel assembly loaded into the core at the end of the cycle is monotonously decreased as the exposure increases. In other words, the infinite multiplication factor of the fuel assembly is proportional to the number of residence cycles in the core. In order to obtain the adequate excess reactivity without loading new fuel assemblies, it is preferable that the fuel assemblies having a short number of residence cycles in the core, among the fuel assemblies to be loaded into the core are collected in an inside-core region which is 70% of a radius of a circumscribed circle of the core (radius of circumscribed circle circumscribing peripheral fuel assembly to be loaded into outermost circumference of core) which is about half the area of the cross-sectional area in the core with high neutron importance. As a result of further investigation, the inventors found a condition of fuel loading of the core determined by a parameter X expressed by the following equation (1).X=Ta/Tb (1) where, Ta: T in a case where fuel exchange is performed, Tb: T in a case where fuel exchange is not performed, T: an average value of t of fuel assembly having shortest loading period loaded into the inside-core region, t: (ΣTs+0.5×ΣTx)/(4+0.5×4), Ts: the number of residence cycles of fuel assemblies laterally adjacent and longitudinally adjacent to fuel assembly having shortest loading period in core cross section, and Tx: the number of residence cycles of fuel assemblies obliquely adjacent to fuel assembly having shortest loading period in horizontal cross section in the core. T is a value obtained by taking weighted average of the number of residence cycles, in the core, of fuel assemblies laterally adjacent, longitudinal adjacent, and diagonally adjacent to a fuel assembly with the shortest loading period, which has maximum reactivity, in the horizontal cross section of the core and is an index indicating a degree of whether or not fuel assemblies having a short loading period are loaded intensively into the core, in a certain fuel disposition. Here, the term “laterally adjacent and longitudinal adjacent in the cross section of the core” means, that is, that it is adjacent to four side surfaces of a channel box having a cross-section square shape constituting the fuel assembly. When fuel assemblies having a short loading period are intensively loaded, the gain of the excess reactivity is increased and the power peaking becomes severe. The parameter X is a ratio of T (Ta) in the case of performing fuel exchange, and T (Tb) in the case of not performing fuel exchange and is an index indicating a degree of how much the fuel assemblies having a short loading period are loaded into the core inside region by the fuel exchange. FIG. 7 is a diagram illustrating a relationship between a parameter X (Ta/Tb) expressed as a core residence period of fuel assemblies adjacent to a fuel assembly having the shortest loading period and excess reactivity, and FIG. 8 is a diagram illustrating a relationship between the parameter X (Ta/Tb) expressed as the core residence period of the fuel assemblies adjacent to a fuel assembly having the shortest loading period and power peaking. As illustrated in FIG. 7, if parameter X (Ta/Tb) is 1.0 or less, gain of the excess reactivity can be obtained. When parameter X (Ta/Tb) is decreased as much as possible, although the gain of the excess reactivity can be obtained, power peaking becomes severe. As illustrated in FIG. 8, when the parameter X (Ta/Tb) is less than 0.8, the power peaking exceeds safety limitation and it becomes impossible to operate safely. As illustrated above, it is understood that it is preferable to set the parameter X (Ta/Tb) to 0.8 or more and 1.0 or less. Further, as illustrated in FIG. 7, since a gain effect having excess reactivity which is larger than the power coastdown operations which obtain excess reactivity can be obtained by decrease in the core power of the boiling water reactor (BWR), it is preferable that the parameter X (Ta/Tb) becomes 0.9 or less. Hereinafter, examples of the invention reflecting study results described above will be described with reference to the drawings. FIG. 1 is a view illustrating a cross section of a core 12 of a boiling water reactor of Example 1 according to an example of the invention, which is a fuel disposition view of a ¼ core, FIG. 2 is a view illustrating t of an inside-core region in the fuel disposition illustrated in FIG. 1. In addition, FIG. 3 is a cross-sectional view of an equilibrium core of a boiling water reactor in an operation cycle in which a new fuel assembly is loaded, which is a fuel disposition view of the ¼ core, and FIG. 4 is a view illustrating an inside-core region t in the fuel disposition illustrated in FIG. 3. For convenience of explanation, coordinate axes (X axis and Y axis) are attached to the ¼ core illustrated in FIG. 1 to FIG. 4. First, a relationship between FIG. 1 and FIG. 3 will be described. In a fuel disposition of the core 12 (¼ core) which is an equilibrium core of FIG. 3 in which a new fuel assembly (first cycle fuel assembly) is loaded into the core 12, a fuel disposition of the core 12 after the fuel exchange becomes a fuel disposition illustrated in FIG. 1 without taking out the fuel assembly from the core 12 and without loading a new fuel assembly, that is, only by changing dispositions of multiple fuel assemblies loaded into the core 12 after one cycle operation (after one cycle burnup). Therefore, in the fuel assembly loaded into the ¼ core illustrated in FIG. 2, only by changing the dispositions of multiple fuel assemblies loaded into the core 12, a value of t for each fuel assembly loaded into the inside-core region after the fuel exchange is illustrated. Here, the inside-core region is a region surrounded by a one-dot chain line in FIG. 2 and is a region of an inside of a circle of 70% of the core circumscribed circle radius (radius of circumscribed circle circumscribing fuel assembly to be loaded into outermost periphery of core 12). In addition, an outside of a circle of 70% of the core circumscribed circle radius is set to an outside-core region. In addition, in FIG. 1 and FIG. 3, the numbers assigned to the respective fuel assemblies to be loaded into the core 12 represent the numbers of residence cycles of the fuel assembly in the core. For example, in FIG. 3, “1” indicating a new fuel assembly (first cycle fuel assembly) newly loaded into the core 12 is assigned to a fuel assembly loaded at a position of coordinates (9, 10). In addition, similarly, “2” indicating a fuel assembly (second cycle fuel assembly) after one cycle burnup (after one cycle operation) is assigned to a fuel assembly loaded at a position of coordinates (8, 9) and “3” indicating a fuel assembly (third cycle fuel assembly) after three cycle burnup (after three cycle operation) is assigned to a fuel assembly loaded at a position of coordinates (9, 8). Similarly, “4” indicating a fourth cycle fuel assembly is assigned to a fuel assembly after four cycle burnup (after four cycle operation) and “5” indicating a fifth fuel assembly is assigned to a fuel assembly after five cycle burnup (after five cycle operation). As described above, in FIG. 1, in the fuel disposition of the core 12 (¼ core) which is the equilibrium core illustrated in FIG. 3, “2” to “6” indicating the second cycle fuel assembly to the sixth cycle fuel assembly are assigned to each fuel assembly since it is the fuel disposition of the core 12 after the fuel exchange is performed by only dispositions of multiple fuel assemblies loaded into the core 12 being changed, without taking out the fuel assembly from the core 12 and without loading a new fuel assembly from the outside of the core after one cycle operation (after one cycle burnup). The core 12 of the boiling water reactor illustrated in FIG. 3 is changed only the disposition position of the fuel assembly loaded into the core 12 in order to obtain the fuel disposition of the core 12 of the boiling water reactor illustrated in FIG. 1 without newly loading anew fuel assembly during the fuel exchange after an operation (one cycle operation) is performed for a predetermined period. Next, in FIG. 2, the value of “t” of the fuel assembly loaded into the inside-core region will be described. As an example, a value of “t” of the fuel assembly loaded at the position of the coordinates (9, 10) is obtained as follows. In FIG. 1, fuel assemblies laterally adjacent to the fuel assembly loaded at the position of the coordinates (9, 10), which is the second cycle fuel assembly are a fifth cycle fuel assembly loaded at the position of the coordinates (8, 10) and a fourth cycle fuel assembly loaded at the position of the coordinates (10, 10). In addition, fuel assemblies longitudinally adjacent to the fuel assembly loaded at the position of the coordinates (9, 10), which is the second cycle fuel assembly are the fourth cycle fuel assembly loaded at the position of coordinates (9, 9) and the fourth cycle fuel assembly loaded at the position of the coordinates (9, 11). In addition, Also, fuel assemblies diagonally adjacent to the fuel assembly loaded at the position of the coordinates (9, 10) which is the second cycle fuel assembly are the third cycle fuel assembly loaded at the position of the coordinates (8, 9), the second cycle fuel assembly loaded at the position of the coordinates (10, 9), the third cycle fuel assembly loaded at the position of the coordinates (8, 11), and the third cycle fuel assembly loaded at the position of the coordinates (10, 11). Therefore, ΣTs and ΣTx in the equation (1) described above are respectivelyΣTs=5(8,10)+4(10,10)+4(9,9)+4(9,11)=17ΣTx=3(8,9)+2(10,9)+3(8,11)+3(10,11)=11.t=(ΣTs+0.5×ΣTx)/(4+0.5×4)=(17+0.5×11)/6=3.75,the value of “t” of the fuel assembly loaded at the position of coordinates (9, 10) illustrated in FIG. 2 is “3.8”. The other second cycle fuel assembly (fuel assembly having the shortest loading period) loaded into the inside-core region are similarly obtained and are as illustrated in FIG. 2. In addition, in FIG. 2, the number of the second cycle fuel assemblies loaded into the inside-core region of the core 12 (¼ core) is 24 and the average value of “t” of the fuel assemblies having the shortest loading period loaded into the inside-core region illustrated in FIG. 2: Σt/24=3.870=3.9 and Ta=3.9. On the other hand, in FIG. 4, the value of “t” of the fuel assembly loaded into the inside-core region will be described. As an example, the value of “t” of the fuel assembly loaded at the position of the coordinates (9, 10) is obtained as follows. In FIG. 3, fuel assemblies laterally adjacent to the fuel assembly loaded at the position of the coordinates (9, 10) which is the first cycle fuel assembly are the fourth cycle fuel assembly loaded at the position of the coordinates (8, 10) and the third cycle fuel assembly loaded at the position of the coordinates (10, 10). In addition, fuel assemblies longitudinally adjacent to the fuel assembly loaded at the position of the coordinates (9, 10) which is the first cycle fuel assembly are the third cycle fuel assembly loaded at the position of the coordinates (9, 9) and the third cycle fuel assembly loaded at the position of the coordinates (9, 11). In addition, fuel assemblies diagonally adjacent to the fuel assembly loaded at the position of the coordinates (9, 10) which is the first cycle fuel assembly are the second cycle fuel assembly loaded at the position of the coordinates (8, 9), the first cycle fuel assembly loaded at the position of the coordinates (10, 9), the second cycle fuel assembly loaded at the position of the coordinates (8, 11), and the second cycle fuel assembly loaded at the position of the coordinates (10, 11). Therefore, ΣTs and ΣTx in the equation (1) described above are respectivelyΣTs=4(8,10)+3(10,10)+3(9,9)+3(9,11)=13ΣTx=2(8,9)+1(10,9)+2(8,11)+2(10,11)=7.t=(ΣTs+0.5×ΣTx)/(4+0.5×4)=(13+0.5×7)/6=2.75,the value of “t” of the fuel assembly loaded at the position of coordinates (9, 10) illustrated in FIG. 4 is “2.8”. The other first cycle fuel assemblies (fuel assemblies with shortest loading period) loaded into the inside-core region are similarly obtained and are as illustrated in FIG. 4. In addition, in FIG. 4, the number of the first cycle fuel assembly loaded into the inside-core region of the core 12 (¼ core) is 24 and the average value of “t” of the fuel assemblies having the shortest loading period loaded into the inside-core region illustrated in FIG. 4: Σt/24=3.025=3.0, Tb=4.0 (average value “t” illustrated in FIG. 4+1). Here, the reason why the average value of “t”+1 illustrated in FIG. 4 is Tb will be described. The value of “t” of each of the fuel assemblies loaded into the inside-core region illustrated in FIG. 4 is the value of “t” of the fuel assembly loaded into the inside-core region of the core 12 illustrated in FIG. 3, that is, it is the value of “t” illustrated in FIG. 3 before burnup. Therefore, since the number of cycle of each fuel assembly is incremented by one after completion of one cycle operation (one cycle burnup) without fuel exchange in the fuel disposition state illustrated in FIG. 4, the value obtained by adding one to the average value of “t” illustrated in FIG. 4 is the T in a case of not performing the fuel exchange, that is, Tb. In the present example, since Ta=3.9 (average value of “t” in FIG. 2) and Tb=4.0 (average value of “t” in FIG. 4+1), X=0.98 and thus the value of X meets 0.8 or more and 1.0 or less. In other words, in the present example, the core can be operated while adequate excess reactivity therein without loading of a new fuel assembly by a configuration to change only disposition positions of multiple fuel assemblies to be loaded into the core and to perform fuel exchange without taking out the fuel assembly from the core 12 and loading a new fuel assembly in the core 12 after one cycle operation (after one cycle burnup), from the fuel disposition of the equilibrium core illustrated in FIG. 3. According to the present example described above, a core of a boiling water reactor that can be operated without loading a new fuel assembly in an operation cycle before the decommissioning can be realized. In addition, according to the present example, the core can be operated while adequate excess reactivity therein without loading a new fuel assembly in the operation cycle before the decommissioning. FIG. 5 is a cross-sectional view illustrating a core 12 of a boiling water reactor of Example 2 according to another example of the invention, which is a fuel disposition view of a ¼ core and FIG. 6 is a view illustrating t of the inside-core region in the fuel disposition illustrated in FIG. 5. The present example is different from Example 1 in that it is configured that only disposition positions of multiple fuel assemblies to be loaded into the core 12 are changed without taking out the fuel assembly from the core 12 and without loading a new fuel assembly from the outside of the core, in particular, a fuel assembly having a short loading period in the core 12 is loaded into the inside-core region and a fuel assembly having a long loading period in the core 12 is loaded into the outside-core region, after one cycle operation (after one cycle burnup), in the fuel disposition of the core 12 (¼ core) which is the equilibrium core illustrated in FIG. 3 described above. The others are the same as those in Example 1. In FIG. 5, in the fuel disposition of the core 12 (¼ core) which is the equilibrium core illustrated in FIG. 3 described above, “2” to “6” indicating the second cycle fuel assembly to the sixth cycle fuel assembly are assigned to each fuel assembly since it is the fuel disposition of the core 12 after the fuel exchange is performed by only the disposition positions of multiple fuel assemblies to be loaded into the core 12 being changed without taking out the fuel assembly from the core 12 and without loading a new fuel assembly from the outside of the core after one cycle operation (after one cycle burnup). The core 12 of the boiling water reactor illustrated in FIG. 3 is changed only the disposition position of the fuel assembly loaded into the core 12 in order to be the fuel disposition of the core 12 of the boiling water reactor illustrated in FIG. 5 without newly loading anew fuel assembly during fuel exchange after an operation (one cycle operation) is performed for a predetermined period. Next, in FIG. 6, the value of “t” of the fuel assembly to be loaded into the inside-core region will be described. As an example, the value of “t” of the fuel assembly loaded at the position of the coordinates (9, 10) is obtained as follows. In FIG. 5, fuel assemblies laterally adjacent to the fuel assembly loaded at the position of the coordinates (9, 10) which is the second cycle fuel assembly are the fourth cycle fuel assembly loaded at the position of the coordinates (8, 10) and the fourth cycle fuel assembly loaded at the position of the coordinates (10, 10). In addition, fuel assemblies longitudinally adjacent to the fuel assembly loaded at the position of the coordinates (9, 10) which is the second cycle fuel assembly are the fourth cycle fuel assembly loaded at the position of coordinates (9, 9) and the fourth cycle fuel assembly loaded at the position of the coordinates (9, 11). In addition, fuel assemblies diagonally adjacent to the fuel assembly loaded at the position of the coordinates (9, 10) which is the second cycle fuel assembly are the third cycle fuel assembly loaded at the position of the coordinates (8, 9), the second cycle fuel assembly loaded at the position of the coordinates (10, 9), the third cycle fuel assembly loaded at the position of the coordinates (8, 11), and the third cycle fuel assembly loaded at the position of the coordinates (10, 11). Therefore, ΣTs and ΣTx in the equation (1) described above are respectivelyΣTs=4(8,10)+4(10,10)+4(9,9)+4(9,11)=16ΣTx=3(8,9)+2(10,9)+3(8,11)+3(10,11)=11.t=(ΣTs+0.5×ΣTx)/(4+0.5×4)=(16+0.5×11)/6=3.58,the value of “t” of the fuel assembly loaded at the position of coordinates (9, 10) illustrated in FIG. 6 is “3.6”. The other second cycle fuel assemblies (fuel assemblies having shortest loading period) loaded into the inside-core region are similarly obtained and are as illustrated in FIG. 6. In addition, in FIG. 6, the number of the second cycle fuel assemblies loaded into the inside-core region of the core 12 (¼ core) is 24 and the average value of “t” of the fuel assemblies having the shortest loading period loaded into the inside-core region illustrated in FIG. 6: Σt/24=3.25=3.3 and Ta=3.3. On the other hand, in FIG. 4, the value of “t” of the fuel assembly to be loaded into the inside-core region will be described. As an example, the value of “t” of the fuel assembly loaded at the position of the coordinates (9, 10) is obtained as follows. In FIG. 3, fuel assemblies laterally adjacent to the fuel assembly loaded at the position of the coordinates (9, 10) which is the first cycle fuel assembly are the fourth cycle fuel assembly loaded at the position of the coordinates (8, 10) and the third cycle fuel assembly loaded at the position of the coordinates (10, 10). In addition, fuel assemblies longitudinally adjacent to the fuel assembly loaded at the position of the coordinates (9, 10) which is the first cycle fuel assembly are the third cycle fuel assembly loaded at the position of the coordinates (9, 9) and the third cycle fuel assembly loaded at the position of the coordinates (9, 11). In addition, fuel assemblies diagonally adjacent to the fuel assembly loaded at the position of the coordinates (9, 10) which is the first cycle fuel assembly are the second cycle fuel assembly loaded at the position of the coordinates (8, 9), the first cycle fuel assembly loaded at the position of the coordinates (10, 9), the second cycle fuel assembly loaded at the position of the coordinates (8, 11), and the second cycle fuel assembly loaded at the position of the coordinates (10, 11). Therefore, ΣTs and ΣTx in the equation (1) described above are respectivelyΣTs=4(8,10)+3(10,10)+3(9,9)+3(9,11)=13ΣTx=2(8,9)+1(10,9)+2(8,11)+2(10,11)=7.t=(ΣTs+0.5×ΣTx)/(4+0.5×4)=(13+0.5×7)/6=2.75,the value of “t” of the fuel assembly loaded at the position of coordinates (9, 10) illustrated in FIG. 4 is “2.8”. The other first cycle fuel assemblies (fuel assemblies with shortest loading period) loaded into the inside-core region are similarly obtained and are as illustrated in FIG. 4. In addition, in FIG. 4, the number of the first cycle fuel assembly loaded into the inside-core region of the core 12 (¼ core) is 24 and the average value of “t” of the fuel assembly having the shortest loading period loaded into the inside-core region illustrated in FIG. 4: Σt/24=3.025=3.0, Tb=4.0 (average value “t” illustrated in FIG. 4+1). In the present example, since Ta=3.3 (average value of “t” in FIG. 6) and Tb=4.0 (average value of “t” in FIG. 4+1), X=0.83 and thus the value of X meets 0.8 or more and 0.9 or less. In other words, in the present example, gain effect of excess reactivity larger than that of power coastdown operations can be obtained as illustrated in FIG. 7 and the core can be operated while adequate excess reactivity therein during the longer period than that of Example 1 without loading of a new fuel assembly by changing only the disposition positions of multiple fuel assemblies to be loaded into the core 12 without taking out the fuel assembly from the core 12 and without loading a new fuel assembly from the outside of the core, in particular, by adopting a configuration in which the fuel exchange is performed which loads fuel assemblies having a short loading period in the core 12 in the inside-core region and loads fuel assemblies having a long loading period in the core 12 in the outside-core region, after one cycle operation (after one cycle burnup), from the fuel disposition of the equilibrium core illustrated in FIG. 3. According to the present example described above, in addition to the effect of Example 1, the core can be operated while ensuring excess reactivity in the core over a longer period. FIG. 9 is a view illustrating a cross section of a core 12 of a boiling water reactor of Example 3 according to another example of the invention, which is a fuel disposition view of a ¼ core and FIG. 10 is a view illustrating t of the inside-core region in the fuel disposition illustrated in FIG. 9. The present example is different from Example 1 in that it is configured that only disposition positions of multiple fuel assemblies to be loaded into the core 12 are changed without taking out the fuel assembly from the core 12 and without loading a new fuel assembly from the outside of the core, in particular, fuel assemblies having a short loading period in the core 12 are loaded into the inside-core region and fuel assemblies having a long loading period in the core 12 are loaded into the outside-core region, and thus a configuration of the present example becomes the fuel disposition illustrated in FIG. 5 of Example 2 after one cycle operation (after one cycle burnup), and thus furthermore, only the disposition positions of multiple fuel assemblies to be loaded into the core 12 are changed without taking out the fuel assembly from the core 12 and loading a new fuel assembly from the outside of the core, in particular, the fuel assemblies having a short loading period in the core 12 are loaded into the inside-core region after another cycle operation (after one cycle burnup), in the fuel disposition of the core 12 (¼ core) which is the equilibrium core illustrated in FIG. 3 described above. In the present example, in the core 12 of the boiling water reactor 12 illustrated in FIG. 3 described above, during fuel exchange after a predetermined period of operation (one cycle operation), without newly loading a new fuel assembly, in order to be the fuel disposition of the core 12 of the boiling water reactor illustrated in FIG. 5, only the disposition position of the fuel assembly loaded into the core 12 is changed, and then furthermore only the disposition position of the fuel assembly loaded into the core 12 is changed in order to be the fuel disposition of the core 12 of the boiling water reactor illustrated in FIG. 9 without newly loading a new fuel assembly after another cycle operation (after one cycle burnup). Next, in FIG. 10, the value of “t” of the fuel assembly to be loaded into the inside-core region will be described. As an example, the value of “t” of the fuel assembly loaded at the position of the coordinates (9, 10) is obtained as follows. In FIG. 9, fuel assemblies laterally adjacent to the fuel assembly loaded at the position of the coordinates (9, 10) which is the third cycle fuel assembly are the fourth cycle fuel assembly loaded at the position of the coordinates (8, 10) and the fourth cycle fuel assembly loaded at the position of the coordinates (10, 10). In addition, fuel assemblies longitudinally adjacent to the fuel assembly loaded at the position of the coordinates (9, 10) which is the second cycle fuel assembly are the fourth cycle fuel assembly loaded at the position of coordinates (9, 9) and the fourth cycle fuel assembly loaded at the position of the coordinates (9, 11). In addition, fuel assemblies diagonally adjacent to the fuel assembly loaded at the position of the coordinates (9, 10) which is the second cycle fuel assembly are the third cycle fuel assembly loaded at the position of the coordinates (8, 9), the third cycle fuel assembly loaded at the position of the coordinates (10, 9), the third cycle fuel assembly loaded at the position of the coordinates (8, 11), and the third cycle fuel assembly loaded at the position of the coordinates (10, 11). Therefore, ΣTs and ΣTx in the equation (1) described above are respectivelyΣTs=4(8,10)+4(10,10)+4(9,9)+4(9,11)=16ΣTx=3(8,9)+3(10,9)+3(8,11)+3(10,11)=12.t=(ΣTs+0.5×ΣTx)/(4+0.5×4)=(16+0.5×12)/6=3.67,the value of “t” of the fuel assembly loaded at the position of coordinates (9, 10) illustrated in FIG. 10 is “3.7”. The other third cycle fuel assemblies (fuel assemblies having shortest loading period) loaded into the inside-core region are similarly obtained and are as illustrated in FIG. 10. In addition, in FIG. 10, the number of the second cycle fuel assemblies loaded into the inside-core region of the core 12 (¼ core) is 42 and the average value of “t” of the fuel assemblies having the shortest loading period loaded into the inside-core region illustrated in FIG. 10: Σt/42=3.802=3.8 and Ta=3.8. On the other hand, in FIG. 6, the value of “t” of the fuel assembly loaded into the inside-core region will be described. As an example, the value of “t” of the fuel assembly loaded at the position of the coordinates (9, 10) is obtained as follows. In FIG. 5, fuel assemblies laterally adjacent to the fuel assembly loaded at the position of the coordinates (9, 10) which is the second cycle fuel assembly are the fourth cycle fuel assembly loaded at the position of the coordinates (8, 10) and the fourth cycle fuel assembly loaded at the position of the coordinates (10, 10). In addition, fuel assemblies longitudinally adjacent to the fuel assemblies loaded at the position of the coordinates (9, 10) which is the second cycle fuel assembly are the fourth cycle fuel assembly loaded at the position of the coordinates (9, 9) and the fourth cycle fuel assembly loaded at the position of the coordinates (9, 11). In addition, fuel assemblies diagonally adjacent to the fuel assembly loaded at position of the coordinates (9, 10) which is the second cycle fuel assembly are the third cycle fuel assembly loaded at the position of the coordinates (8, 9), the second cycle fuel assembly loaded at the position of the coordinates (10, 9), the third cycle fuel assembly loaded at the position of the coordinates (8, 11), and the third cycle fuel assembly loaded at the position of the coordinates (10, 11). Therefore, ΣTs and ΣTx in the equation (1) described above are respectivelyΣTs=4(8,10)+4(10,10)+4(9,9)+4(9,11)=16ΣTx=3(8,9)+2(10,9)+3(8,11)+3(10,11)=11.t=(ΣTs+0.5×ΣTx)/(4+0.5×4)=(16+0.5×11)/6=3.58,the value of “t” of the fuel assembly loaded at the position of coordinates (9, 10) illustrated in FIG. 6 is “3.6”. The other second cycle fuel assemblies (fuel assemblies with shortest loading period) loaded into the inside-core region are similarly obtained and are as illustrated in FIG. 6. In addition, in FIG. 6, the number of the second cycle fuel assemblies loaded into the inside-core region of the core 12 (¼ core) is 24 and the average value of “t” of the fuel assemblies having the shortest loading period loaded into the inside-core region illustrated in FIG. 6: Σt/24=3.25=3.3 and Tb=4.3 (average value of “t” illustrated in FIG. 6+1). In the present example, since Ta=3.8 (average value of “t” in FIG. 10) and Tb=4.3 (average value of “t” in FIG. 6+1), X=0.88 and thus the value of X meets 0.8 or more and 0.9 or less. In other words, in the present example, one cycle operation can be further continued from the core 12 of the boiling water reactor in Example 1 described above by only the dispositions of multiple fuel assemblies being loaded into the core 12 being changed without taking out the fuel assembly from the core 12 and without loading a new fuel assembly from outside the core, in particular, by fuel assemblies having a short loading period in the core 12 being loaded into the inside-core region and a fuel assembly having a long loading period in the core 12 being loaded into the outside-core region, and thus a configuration of the present example becoming the fuel disposition illustrated in FIG. 5 of Example 2 after one cycle operation (after one cycle burnup) and then furthermore only the dispositions of multiple fuel assemblies loaded into the core 12 being changed without taking out the fuel assembly from the core 12 and without loading a new fuel assembly from outside the core, in particular, by a configuration in which a fuel assembly having a short loading period in the core 12 is loaded into the inside-core region after another cycle operation (after one cycle burnup), in the fuel disposition of the core 12 (¼ core) which is an equilibrium core in FIG. 3 described above. According to the present example described above, in addition to the effect of Example 1, further one cycle operation can be continued and the core can be operated while adequate excess reactivity in the core over a long period. The invention is not limited to the examples described above but includes various modification examples. For example, the examples described above are described in detail in order to explain the invention easily and are not necessarily limited to those including all the configurations described. In addition, it is possible to replace a portion of the configuration of one example with the configuration of another example and, in addition, the configuration of another example can be added to the configuration of one example. 10 boiling water reactor 11 reactor pressure vessel 12 core 13 core plate 14 upper portion lattice plate 15 fuel support 16 core shroud 17 down comer 18 gas-water separator 19 steam dryer 20 shroud head 21 jet pump 22 control rod guide tube 23 control rod drive 24 lower mirror 25 main steam tube 26 water supply tube 27 recirculation system tube 28 recirculation pump 29 lower plenum
062367021	summary	BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel assembly spacer grid for nuclear reactors, and more particularly to a fuel assembly spacer grid used for a nuclear fuel assembly placed in a reactor core at a nuclear power plant, which spacer grid is provided with swirl deflectors, hydraulic pressure springs, and wear resistant springs. 2. Description of the Prior Art Referring to FIG. 1, a nuclear reactor is illustrated in which a nuclear fuel assembly is placed in a reactor core denoted by the reference numeral 101. Typically, a spacer grid 103 is used to firmly support fuel elements 111 of the nuclear fuel assembly in a state placed in the reactor core. Such a spacer grid 103 consists of a plurality of longitudinally-extending parallel vertical straps and a plurality of laterally-extending parallel vertical straps perpendicularly interconnecting the longitudinally-extending straps. The fuel elements 111 are placed in internal spaces defined by the interconnecting straps, respectively. The spacer grid 103 serves to prevent the nuclear fuel from being damaged due to vibrations of the fuel elements 111 caused by a flow of cooling water in the reactor core. The spacer grid 103 also maintains a desired space between each fuel element 111 and a guide tube 102 arranged adjacent to the fuel element 111 even when the nuclear reactor is subjected to an earthquake or other external impact. In other words, the spacer grid 103 always provides a flow passage for the cooling water, thereby keeping a desired cooling function for the reactor core. In this regard, active research efforts have been made to provide a spacer grid capable of suppressing vibrations and abrasion of fuel elements while enhancing a resistance to lateral impact. In order to support the fuel elements 111, the spacer grid 103 has a plurality of protrusions which are typically formed by forming slots at desired portions of the straps, and depressing portions of the straps each positioned between adjacent slots. Of the protrusions, those, which have a low strength, thereby supporting fuel elements while being depressed by those fuel elements, are called "springs". On the other hand, protrusions, which have a high strength, thereby supporting fuel elements while exhibiting little or no deformation, are called "dimples". When springs are subjected to irradiation of neutrons for an extended period of time, they change the property of their material. As a result, the springs exhibit a gradual reduction in elasticity. This results in a reduction in the support force of the springs for the fuel elements, thereby causing those elements to vibrate. Due to such vibrations, the fuel elements may be subjected to a fretting wear at portions contacting the fuel element-supporting elements of the straps. Such a fretting wear of the fuel elements results in a perforation of the fuel elements which, in turn, causes a leakage of radioactivity. In connection with this, several reports have been made. It is known that an important geometric factor causing the above mentioned fretting wear of fuel elements is the shape of contacts between elements being in contact with each other. In conventional configurations, the contacts between fuel elements and springs or between fuel elements and dimples have a point or line contact shape. In terms of fretting wear, the line contact shape provides a high ability of suppressing vibrations and a high abrasion resistance, as compared to the point contact shape. This is because an increase in contact area at a constant elasticity of springs results in a reduction in the contact pressure causing a depression of those springs, thereby suppressing a fretting wear of fuel elements contacting the springs. In the case of springs in which elasticity depends only on a material used, as in the above mentioned springs, a reduction in elasticity occurs inevitably due to an irradiation of neutrons onto the springs. In order to eliminate such a drawback, it is necessary to increase the initial spring force of springs. Alternatively, an additional force capable of compensating for the reduced mechanical property of springs should be applied to those springs. However, an increase in the initial spring force may result in an increase in the force required upon initially placing a nuclear fuel assembly, thereby causing a damage of fuel elements. On the other hand, fuel elements placed in a reactor core exhibit a non-uniform heat flux distribution. Due to such a non-uniform heat flux distribution, a severe increase in the temperature of a cooling water in the reactor core occurs at areas surrounding fuel elements generating a higher heat flux, namely, exhibiting a higher temperature. Meanwhile, bubbles may be locally formed on the surfaces of fuel elements. Where the formation of such bubbles may become severe, thereby covering the surfaces of fuel elements, an abrupt degradation in heat transfer efficiency occurs. This results in an abrupt increase in temperature on the surface of fuel elements. In this case, the temperature of fuel elements themselves or pallets present in the fuel elements may reach a melting point of the fuel elements or pallets. To this end, spacer grids also have a function for forcibly mixing flows of cooling water flowing along areas surrounding fuel elements, thereby obtaining a uniform temperature of the fuel elements while achieving an improvement in the heat transfer performance at the surfaces of the fuel elements. Such a function of spacer grids assists a safe operation of nuclear reactors. For such a function, spacer grids, which include elements for supporting fuel elements, may be attached with separate flow mixing devices adapted to enhance the heat transfer performance. A typical one of conventional flow mixing methods is a method in which cooling water forms a strong wake when it passes through a spacer grid, thereby mixing flows of the cooling water to promote a temperature uniformity. In such a method, however, the flow mixing function is greatly attenuated as the cooling water flows downstream away from the spacer grid. Another conventional flow mixing method is a forced swirling method. In accordance with this method, cooling water is swirled in such a manner that cooling water flows of a high density are forced to flow toward the surfaces of fuel elements with bubbles of a low density being concentrated toward the center of swirling. In this case, the layer of the bubbles serves to prevent a reduction in the heat transfer performance, thereby achieving an improvement in the cooling performance of fuel elements. It is known that the forced swirling method exhibits a slow attenuation in flow mixing effect generated when cooling water passes through the spacer grid, as compared to the wake forming method. Recent developments of spacer grids are focused on the formation of swirling flows. The loss of pressure in a cooling water flow generated when the cooling water passes an obstacle depends mainly upon an area projected onto a plane normal to the flow direction of the cooling water. The provision of a flow mixer results in an additional pressure loss because an increase in the projected area causes a reduction in the area through which the cooling water flows. Such an increase in pressure loss results in an increase in the load applied to a pump for pumping the cooling water. For this reason, there is a problem in that the flow rate of the cooling water flowing in the nuclear reactor decreases. Therefore, where a flow mixer is attached to the spacer grid, a design capable of minimizing the loss of pressure at the same projected area should be provided. Recent developments of nuclear fuel are concentrated on a highly burn-up and non-defective fuel. In the case of a highly-combustible fuel, an increase in the nuclear fuel concentration may be involved. In this case, a severe heat flux peaking phenomenon may occur. Here, the output peaking phenomenon is a phenomenon wherein a part of fuel elements generate a heat flux considerably higher than the mean heat flux of those fuel elements. Where such a severe heat flux peaking phenomenon occurs, a severe boiling phenomenon occurs on the surfaces of fuel elements. This results in a high possibility of a great degradation in heat transfer rate. To this end, it is required to develop a spacer grid with a superior cooling performance over conventional spacer grids. Due to a high burn-up capacity, the using period of the nuclear fuel is extended. In this case, the amount of neutrons irradiated onto the spacer grid increases. This is an important consideration in that the problem associated with a decrease in spring force may occur due to a change in the property of the spacer grid material. For the development of a non-defective fuel, therefore, it is necessary, in terms of fretting wear, to provide a mechanism capable of compensating for a decrease in the spring force required for suppressing vibrations of fuel elements. SUMMARY OF THE INVENTION Therefore, an object of the invention is to solve the above mentioned problems involved in conventional fuel assembly spacer grids, and to provide a fuel assembly spacer grid provided with swirl deflectors each capable of generating a strong swirling flow of cooling water while maintaining the swirling motion far downstream of the cooling water flow. Another object of the invention is to provide a fuel assembly spacer grid provided with swirl deflectors each capable of generating a strong swirling flow of cooling water while using a small bent angle at which the swirl deflector comes into contact with the cooling water, thereby minimizing the loss of pressure in the cooling water flow caused by the provision of the swirl deflector. Another object of the invention is to provide a fuel assembly spacer grid capable of utilizing the hydraulic drag force on spring in a cooling water flow passing through the spacer grid as an additional spring force, thereby compensating for a decrease in the initial mechanical spring force caused by a change in the property of the material of the spacer grid occurring in a reactor core where the spacer grid is disposed. Another object of the invention is to provide a fuel assembly spacer grid in which the portions of the springs and dimples thereof contacting fuel elements have a conformal surface contact shape in such a manner that those contact portions are in surface contact with the fuel elements, thereby effectively suppressing vibrations of the fuel elements and greatly reducing the possibility of a fretting abrasion of the fuel elements resulting in a damage of the fuel elements. In accordance with the present invention, these objects are accomplished by providing a fuel assembly spacer grid for a nuclear reactor comprising a plurality of longitudinally-extending, parallel, spaced vertical straps, and a plurality of laterally-extending, parallel, spaced vertical straps perpendicularly interconnecting the longitudinally-extending straps, the interconnecting straps supporting fuel elements of a nuclear fuel assembly, further comprising: a plurality of swirl deflectors respectively arranged at interconnections between the interconnecting straps on upper ends of the interconnecting straps and adapted to generate a swirling flow from a cooling water passing through the spacer grid, each of the swirl deflectors having a plurality of vanes bent to have an air vane shape.
041522877	summary	BACKGROUND OF THE INVENTION This invention relates to the solidification of radioactive liquid waste in a low leachability form. Radioactive waste solutions are obtained in most conventional separation processes in which uranium, plutonium, or other radionuclides are recovered from irradiated nuclear fuels. Recovery methods are usually based on solvent extraction, on precipitation, or on ion exchange techniques. The aqueous waste solutions left after the separation processes contain the bulk of the radioactive fission products in a highly dilute form, salts that have been added and possibly reducing or oxidizing agents that were added for the conversion of actinides from one valence to another. Disposal of liquid radioactive waste to the environment is undesirable since the wastes continue to release dangerous radiation for thousands of years. Liquid radioactive wastes are sometimes highly acidic and corrode or destroy containers, even those made of stainless steel or other resistant materials, after a very long period of time. For this reason, it is undesirable to bury liquid waste in the ground due to the possible contamination of ground waters or to dispose such waste at sea. It is necessary to reduce the bulk of the waste solutions and to convert the radioactive fission products into water insoluble form. Prior art has attempted to accomplish this in a number of ways, such as by dehydration and calcination, as taught in the U.S. Pat. No. 3,008,904; solidification of the radioactive waste as taught by U.S. Pat. No. 3,507,801; and the use of a fluidized bed to calcine the radioactive material as described in U.S. Pat. No. 3,862,296 and in the article "Technical and Economic Comparison of Methods for Solidifying and Storing High-Activity Liquid Waste Arising in the Reprocessing of Irradiated Fuel Elements from Water-Cooled and Water-Moderated Reactors" from the Symposium on the Management of Radioactive Wastes from Fuel Reprocessing of the Organisation for Economic Co-Operation and Development in Paris, dated March, 1973. The prior art processes, while effective in reducing the volume of waste material and the problem of the corrosive nature of the waste, still have certain inherent drawbacks, particularly as regards the use of the fluidized bed to calcine the waste material. The fluidized bed resulted in a product which was finely divided and susceptible to leaching when exposed to water. Production of a granular product without excessive fines requires that the introduction of feed be closely controlled to produce particles within a narrow size range and that the elutriation of fines be kept low. It has been proposed to calcine the radioactive waste, mix it with glass frit, e.g., a borosilicate glass frit, and then melt the mixture to form a mass of glass in which the radioactive material is dispersed. This produces a product which is very resistive to leaching. Such as process is disclosed in U.S. Atomic Energy Commission (or Energy Research and Development Administration) Report BNWL 1667. However, to secure a uniform product, it is necessary to mix the calcine and frit. The highly radioactive character of the calcine makes it necessary to have specialized mixing equipment, which adds to the cost and complexity of the plant. SUMMARY OF THE INVENTION The foregoing and other difficulties are overcome by the present method which utilizes a fluidized-bed calciner to simplify the conversion of liquid radioactive waste to a solidified glass form. The invention comprises, in brief, the proportional addition of a glass frit or similar material directly to a fluidized bed wherein it is coated or intimately mixed with radioactive calcine. The coated materials are of such a nature as to permit them to be drained and elutriated from the bed directly into a melter for conversion to glass which fixes the radioactive caline waste.
046845046	abstract	A fuel assembly for use at non-control rod locations of a nuclear reactor core includes top and bottom nozzles and longitudinal structural members extending between and attached to the nozzles for forming an integral unitary structure. One or more of the structural members includes an elongated hollow cladding tube extending between the top and bottom nozzles and end plugs secured to opposite ends of the tube for hermetically sealing and attaching the tube to the top and bottom nozzles. The improvements in the structural member relate to features for reducing fuel assembly bow. Such features relate to a quantity of thermal or irradiation-induced creep resistant material and pretensioning means positioned within the tube. The creep resistant material is a ceramic material in stacked pellet form and coated with a burnable adsorber material. The pretensioning means applies a predetermined compressive load to the ceramic pellet stack and reacts the load so as to preload the tube in a state of pretension having a magnitude sufficient to substantially counteract an axial load typically transmitted through the unitary structure of the fuel assembly and thereby greatly reduce the compressive stress in the structural member tube. There are two embodiments of the pretensioning means. In one embodiment, it is an elongated bellows type device positioned within the tube between the ceramic pellet stack and one of the tube ends, with the interior of the bellows type device being pressurized to create a predetermined axial force therein which places the ceramic pellet stack in compression and the tube in the state of pretension. In the other embodiment, it is an arrangement of belleville springs positioned within the tube between the ceramic pellet stack and one of the tube ends and stacked both in series and in parallel.
055704085	abstract	A system comprising a novel combination of a multiple-channel monolithic capillary optic and an x-ray source with a spot size of less than 300 microns to produce a high intensity small diameter x-ray beam is described. A system of this invention can be easily adapted for use in the analysis of small samples where an intense quasi-parallel, or converging x-ray beam is required.
	description	This application is based upon and claims benefit of priority from the Japanese Patent Application No. 2017-25738, filed on Feb. 15, 2017, the entire contents of which are incorporated herein by reference. The present invention relates to a charged particle beam writing method. With an increase in the packing density of LSIs, the required linewidths of circuits included in semiconductor devices become finer year by year. To form a desired circuit pattern on a semiconductor device, a method is employed in which a high-precision original pattern formed on quartz (i.e., a mask, or also particularly called reticle, which is used in a stepper or a scanner) is transferred to a wafer in a reduced manner by using a reduced-projection exposure apparatus. The high-precision original pattern is written by using an electron-beam writing apparatus, in which a so-called electron-beam lithography technique is employed. In an electron beam writing apparatus, pattern-writing positional errors result from physical phenomena, such as substrate flexure, charging of resist applied to a substrate, and distortion in shape of an electron-beam deflection field. For this reason, correction coefficients for correcting the positional errors resulting from the physical phenomena are calculated and input to the writing apparatus. In traditional writing position correction, for example, a correction coefficient for distortion in shape of an electron-beam deflection field is obtained in a state where physical phenomena, such as substrate flexure and resist charging, have occurred. In other words, the correction coefficient is determined such that the coefficient is affected by the physical phenomena other than the physical phenomenon associated with a positional error to be corrected. Disadvantageously, there is a limit to improvement in writing positional accuracy. In one embodiment, a charged particle beam writing method is for writing a pattern on a substrate by irradiating the substrate with a charged particle beam. The substrate is placed on a movable stage and coated with resist. The method includes writing a first evaluation pattern in a writing area located in central part of a first substrate having a charge dissipation layer (CDL) on resist while stopping the stage to calculate, based on a position of the written first evaluation pattern, a first correction coefficient for correcting a positional error, correcting a writing position in a writing area located in central part of a second substrate having no CDL on resist using the first correction coefficient and writing a second evaluation pattern in the writing area of the second substrate while stopping the stage to calculate, based on a position of the written second evaluation pattern, a second correction coefficient for correcting a positional error, correcting a writing position in a writing area located in central part of a third substrate having CDL on resist using the first correction coefficient and writing a third evaluation pattern in the writing area of the third substrate while moving the stage to calculate, based on a position of the written third evaluation pattern, a third correction coefficient for correcting a positional error, correcting a writing position in a writing area larger than central part of a fourth substrate having CDL on resist using the first correction coefficient and writing a fourth evaluation pattern in the writing area of the fourth substrate while stopping the stage to calculate, based on a position of the written fourth evaluation pattern, a fourth correction coefficient for correcting a positional error, and computing a corrected position, at which positional deviation of the charged particle beam is corrected, on a surface of the substrate using the first, second, third, and fourth correction coefficients and irradiating the corrected position with the charged particle beam to write a predetermined pattern. Hereinafter, an embodiment of the present invention will be described based on the drawings. FIG. 1 is a schematic diagram of an electron beam writing apparatus according to a first embodiment of the present invention. The electron beam writing apparatus 100 illustrated in FIG. 1 is a variable-shaped writing apparatus and includes a writing unit 150 and a control unit 160. The writing unit 150 includes an electron optical column 102 and a writing chamber 103. The electron optical column 102 accommodates an electron gun 201, an illumination lens 202, a blanker 212, a blanking aperture 214, a first shaping aperture 203, a projection lens 204, a first shaping deflector 220, a second shaping deflector 222, a second shaping aperture 206, an objective lens 207, a main deflector 232 (first objective deflector), a sub-deflector 230 (second objective deflector), and a sub-sub-deflector 234 (third objective deflector). The first shaping deflector 220 and the second shaping deflector 222 each include eight pairs of (or sixteen) electrodes circumferentially spaced uniformly from one another. The deflectors are configured to deflect an electron beam when voltage is applied between the opposed electrodes. The writing chamber 103 accommodates an XY stage 105. A substrate 101, serving as a writing target, is placed on the XY stage 105. The substrate 101 is, for example, a mask substrate fabricated by forming a metal light-shielding layer made of, for example, chromium, on a quartz substrate and coating the metal light-shielding layer with resist. The control unit 160 includes a control computer 110, a deflection control circuit 120, a stage position detector 130, and memories 140 and 142, such as magnetic disk units. The control computer 110 includes a corrected-position computing unit 112 and a write data processing unit 114. The corrected-position computing unit 112 and the write data processing unit 114 may be implemented by hardware or may be implemented by software. The deflection control circuit 120 controls the amount of deflection by each of the blanker 212, the first shaping deflector 220, the second shaping deflector 222, the main deflector 232, the sub-deflector 230, and the sub-sub-deflector 234. The stage position detector 130 includes a laser distance measuring device and detects the position of the XY stage 105. The memory 140 (storage unit) stores write data (layout data), including a plurality of figure patterns, input from the outside. The memory 142 stores correction coefficients for correcting positional deviation of an electron beam 200 to be applied to the substrate 101. A method of calculating correction coefficients will be described later. A description of other control circuits for controlling an operation of the writing unit 150 is omitted. When the electron beam 200, emitted from the electron gun 201 (emitting unit) disposed in the electron optical column 102, passes through the blanker 212 (blanking deflector), the electron beam 200 is controlled by the blanker 212 as follows. In a beam ON state, the electron beam 200 is controlled so as to pass through the blanking aperture 214. In a beam OFF state, the electron beam 200 is deflected such that the whole of the beam is interrupted by the blanking aperture 214. The electron beam 200 passed through the blanking aperture 214 for a period between the time when the beam is changed from the beam OFF state to the beam ON state and the time when the beam is changed to the beam OFF state corresponds to a one-time electron beam shot. The blanker 212 controls the direction of the electron beam 200 passing therethrough to alternately generate the beam ON state and the beam OFF state. For example, a deflection voltage is not applied to the blanker 212 in the beam ON state, and the deflection voltage is applied to the blanker 212 in the beam OFF state. A dose per shot of the electron beam 200 to be applied to the substrate 101 is adjusted depending on irradiation time for each shot. The electron beam 200 of each shot generated by allowing the beam to pass through the blanker 212 and the blanking aperture 214 is applied to the entire first shaping aperture 203 having a rectangular opening 32 (refer to FIG. 2) through the illumination lens 202. The electron beam 200 passes through the opening 32 of the first shaping aperture 203, so that the electron beam 200 is shaped into a rectangle. The electron beam 200, serving as a first aperture image, passed through the first shaping aperture 203 is projected onto the second shaping aperture 206 having an opening 34 (refer to FIG. 2) through the projection lens 204. At this time, the first shaping deflector 220 and the second shaping deflector 222 perform deflection control on the first aperture image to be projected onto the second shaping aperture 206, so that the electron beam passing through the opening 34 can be changed in shape and dimension, or subjected to variable shaping. The electron beam 200, serving as a second aperture image, passed through the opening 34 of the second shaping aperture 206 is focused by the objective lens 207. The electron beam 200 is deflected at three stages by the main deflector 232, the sub-deflector 230, and the sub-sub-deflector 234 and is then applied to a target position on the substrate 101 placed on the XY stage 105. FIG. 2 is a schematic perspective view explaining beam shaping by the first shaping aperture 203 and the second shaping aperture 206. The first shaping aperture 203 has the rectangular (rectangular or square) opening 32 for shaping the electron beam 200. The second shaping aperture 206 has the variable-shaping opening 34 for shaping the electron beam 200 passed through the opening 32 of the first shaping aperture 203 into a desired shape. The variable-shaping opening 34 has an octagonal shape obtained by combining a hexagonal portion with a rectangular portion such that the rectangular portion connects to the hexagonal portion. The electron beam 200 emitted from the electron gun 201 and passed through the opening 32 of the first shaping aperture 203 is deflected by the first shaping deflector 220 and the second shaping deflector 222. The electron beam 200 then passes through the variable-shaping opening 34, causing the electron beam to have a desired shape and dimensions. The electron beam, passed through part of the variable-shaping opening 34 of the second shaping aperture 206, having the desired shape and dimensions is applied to the substrate 101 placed on the XY stage 105 continuously moving in a predetermined direction (e.g., X direction). Specifically, the shape 36 of the beam allowed to pass through both the opening 32 of the first shaping aperture 203 and the variable-shaping opening 34 of the second shaping aperture 206 is written in a writing area of the substrate 101 placed on the XY stage 105 continuously moving in the X direction. In the case of FIG. 2, the electron beam 200 passes through the opening 32 of the first shaping aperture 203, so that the beam is shaped into a rectangle. Then, the electron beam 200 passes through the variable-shaping opening 34 of the second shaping aperture 206, so that the beam is shaped into an isosceles right triangle in cross-section perpendicular to the axis of the beam. In the present embodiment, the first shaping deflector 220 adjusts the shape of a shot and the second shaping deflector 222 adjusts the size of the shot. FIG. 3 is a schematic diagram explaining a writing area. Referring to FIG. 3, a writing area 10 of the substrate 101 is virtually divided into a plurality of stripe regions 20, which are strip-shaped parts having a width in which the main deflector 232 can perform deflection and are arranged in, for example, the y direction. Each stripe region 20 is virtually divided into a plurality of mesh-like sub-fields (SFs) 30 having a size in which the sub-deflector 230 can perform deflection. Each SF 30 is virtually divided into a plurality of mesh-like tertiary fields (TFs) 40 having a size in which the sub-sub-deflector 234 can perform deflection. A shot figure is written at each shot position 42 in each TF 40. It is desirable that the number of TFs in each SF be a number at which a writing operation is not delayed by thermal diffusion computation for the TFs. For example, each of the number of columns of TFs and the number of rows of TFs is preferably less than or equal to 10, more preferably less than or equal to 5. To perform writing on the substrate 101 using the shaped electron beam 200, the main deflector 232 deflects the shaped electron beam 200 to a reference position in an SF 30. When the XY stage 105 is moving, the main deflector 232 deflects the electron beam 200 such that the beam follows the moving XY stage 105. The sub-deflector 230 deflects the shaped electron beam 200 from the reference position in the SF 30 to a reference position in a TF 40 in the SF 30. The sub-sub-deflector 234 deflects the electron beam 200, and the deflected electron beam 200 is applied to each position in the TF 40. The write data processing unit 114 reads write data (pattern data) from the memory 140 and performs multi-stage data conversion on the write data to generate shot data specific to the apparatus. The shot data includes a figure type, a size, and a shot position for each shot. The corrected-position computing unit 112 reads a correction coefficient from the memory 142 and computes the amount of correction for correcting positional deviation of the electron beam 200 on the basis of the position and moving speed of the XY stage 105. The corrected-position computing unit 112 computes a corrected writing position based on the correction amount. The deflection control circuit 120 receives the shot data and the corrected writing position from the control computer 110, mathematically calculates the amount of deflection for each of the blanker 212, the first shaping deflector 220, the second shaping deflector 222, the main deflector 232, the sub-deflector 230, and the sub-sub-deflector 234, and outputs a control signal to each of these deflectors. Consequently, a predetermined pattern is written at a desired position. Correction coefficients to be stored in the memory 142 will now be described. In electron beam writing, various physical phenomena result in deviation of the trajectory of an electron beam, causing deviation of a writing position. The correction coefficients are used to correct positional deviation or errors resulting from the physical phenomena. A correction coefficient is defined for each physical phenomenon. In the present embodiment, a correction coefficient for field distortion, a correction coefficient for resist charging, a correction coefficient for an eddy current, and a correction coefficient for substrate flexure are obtained, and the correction coefficients for the four physical phenomena are stored in the memory 142. The field distortion refers to distortion in shape of deflection fields (main fields, sub-fields, and tertiary fields) for the main deflector 232, the sub-deflector 230, and the sub-sub-deflector 234. Distortion in shape of deflection fields leads to deviation of a writing position. The resist applied to the substrate 101 is an organic insulating layer. Some of electrons entered the resist accumulate in the resist and the surface of the resist (resist charging). An electrostatic force associated with the accumulation of electrons causes deviation of the trajectory of an electron beam, leading to deviation of a writing position. To increase the resolution of an electron beam on the surface of the substrate 101, the objective lens 207 is brought close to the substrate 101. This results in “in-lens” arrangement in which the substrate 101 is exposed to the magnetic field of the lens. In the “in-lens” arrangement, the magnetic field of the objective lens 207 passes through the metal light-shielding layer of the substrate 101. Movement of the XY stage 105, on which the substrate 101 is placed, causes an eddy current in the substrate 101. A magnetic field generated by the eddy current causes deviation of the trajectory of the electron beam. A change in thickness of the metal light-shielding layer or a change in moving speed of the XY stage 105 results in a change in strength of the magnetic field generated by the eddy current. The substrate 101 is supported by three supporting pins arranged on the XY stage 105. The substrate 101 flexes due to its own weight. If the substrate 101 flexes and the surface thereof is uneven, or not flat, a writing position is deviated. In the present embodiment, a correction coefficient for correcting positional deviation resulting from one of the four physical phenomena including field distortion, resist charging, an eddy current, and substrate flexure is calculated so as not to be affected by the other three physical phenomena. Resist charging can be prevented by, for example, applying a charge dissipation layer (CDL) to the resist on the substrate 101. An eddy current can be prevented by stopping the XY stage 105 and performing static writing. Central part of the substrate 101, for example, 3- to 4-cm square central part of the substrate 101, is less likely to flex and is substantially flat. Using the central part of the substrate 101 as a writing area can reduce or eliminate the effect of substrate flexure. A method of calculating correction coefficients for the physical phenomena will now be described with reference to a flowchart of FIG. 4. An evaluation pattern (first evaluation pattern) is statically written in central part of a substrate 101 having CDL applied to the resist (step S101). For example, the evaluation pattern includes a cross pattern. The CDL can be made of a known material. After the evaluation pattern is written, development is performed to form a resist pattern. Then, the metal light-shielding layer is etched by using the resist pattern as a mask, the resist is removed, and cleaning is performed, thus forming a light-shielding-layer pattern. The position of the light-shielding-layer pattern is measured and the amount of positional deviation from a design value is computed, thus determining a first correction coefficient for correcting the positional deviation (step S102). In writing of step S101, resist charging is prevented by coating the resist with the CDL. In addition, an eddy current is prevented by performing static writing. Additionally, the effect of substrate flexure is reduced or eliminated by writing the evaluation pattern in the central part of the substrate 101. Therefore, the first correction coefficient obtained in step S102 is a correction coefficient for correcting positional deviation associated with field distortion. The first correction coefficient is stored in the memory 142. Then, an evaluation pattern (second evaluation pattern) is statically written in central part of another substrate 101 using the first correction coefficient (step S103). The resist is not coated with CDL. After the evaluation pattern is written, development is performed to form a resist pattern. Then, the metal light-shielding layer is etched by using the resist pattern as a mask, the resist is removed, and cleaning is performed, thus forming a light-shielding-layer pattern. The position of the light-shielding-layer pattern is measured and the amount of positional deviation from the design value is computed, thus determining a second correction coefficient for correcting the positional deviation (step S104). In writing of step S103, an eddy current is prevented by performing static writing. In addition, the effect of substrate flexure is reduced or eliminated by writing the evaluation pattern in the central part of the substrate 101. Additionally, since the first correction coefficient is used to correct the writing position for the evaluation pattern, positional deviation associated with field distortion is reduced or eliminated. Therefore, the second correction coefficient obtained in step S104 is a correction coefficient for correcting positional deviation associated with resist charging. Then, an evaluation pattern (third evaluation pattern) is written in central part of another substrate 101 having CDL applied to the resist using the first correction coefficient while the XY stage is being moved (continuous writing) (step S105). After the evaluation pattern is written, development is performed to form a resist pattern. Then, the metal light-shielding layer is etched by using the resist pattern as a mask, the resist is removed, and cleaning is performed, thus forming a light-shielding-layer pattern. The position of the light-shielding-layer pattern is measured and the amount of positional deviation is computed, thus determining a third correction coefficient for correcting the positional deviation (step S106). In writing of step S105, resist charging is prevented by coating the resist with CDL. In addition, the effect of substrate flexure is reduced or eliminated by writing the evaluation pattern in the central part of the substrate 101. Additionally, since the first correction coefficient is used to correct the writing position for the evaluation pattern, positional deviation associated with field distortion is reduced or eliminated. Therefore, the third correction coefficient obtained in step S106 is a correction coefficient for correcting positional deviation associated with an eddy current. Then, an evaluation pattern (fourth evaluation pattern) is statically written on another substrate 101 having CDL applied to the resist using the first correction coefficient (step S107). This evaluation pattern is written not only in central part of the substrate 101 but also in as wide a range of a writable area as possible. After the evaluation pattern is written, development is performed to form a resist pattern. Then, the metal light-shielding layer is etched by using the resist pattern as a mask, the resist is removed, and cleaning is performed, thus forming a light-shielding-layer pattern. The position of the light-shielding-layer pattern is measured and the amount of positional deviation is computed, thus determining a fourth correction coefficient for correcting the positional deviation (step S108). In writing of step S107, resist charging is prevented by coating the resist with CDL. In addition, an eddy current is prevented by performing static writing. Additionally, since the first correction coefficient is used to correct the writing position for the evaluation pattern, positional deviation associated with field distortion is reduced or eliminated. Therefore, the fourth correction coefficient obtained in step S108 is a correction coefficient for correcting positional deviation associated with substrate flexure. The first to fourth correction coefficients for the four physical phenomena including field distortion, resist charging, an eddy current, and substrate flexure are stored in the memory 142. For actual writing on a product, the corrected-position computing unit 112 reads the first to fourth correction coefficients from the memory 142 and computes correction amounts for correcting positional deviation of the electron beam 200. The corrected-position computing unit 112 computes a corrected position by adding the correction amounts to design coordinates. The electron beam 200 is applied to the corrected position, thus writing a predetermined pattern. In the present embodiment, the first to fourth correction coefficients are determined while the effects of the physical phenomena other than the physical phenomenon associated with a positional error or deviation to be corrected are being reduced or eliminated. The position is corrected using the first to fourth correction coefficients, thus improving writing positional accuracy. In the above-described first embodiment, writing is performed under writing conditions where the physical phenomena other than the physical phenomenon associated with a positional error or deviation to be corrected are eliminated, and a plurality of correction coefficients for the physical phenomena are obtained. The correction coefficients may be obtained by sequentially using the calculated correction coefficients. A method of calculating the correction coefficients in accordance with a second embodiment will now be described with reference to a flowchart of FIG. 5. Steps S201 to S204 of calculating the first and second correction coefficients are the same as steps S101 to S104 in FIG. 4. A description of steps S201 to S204 is omitted. An evaluation pattern is written in central part of a substrate 101 using the first and second correction coefficients while the XY stage is being moved (continuous writing) (step S205). The resist is not coated with CDL. After the evaluation pattern is written, development is performed to form a resist pattern. Then, the metal light-shielding layer is etched by using the resist pattern as a mask, the resist is removed, and cleaning is performed, thus forming a light-shielding-layer pattern. The position of the light-shielding-layer pattern is measured and the amount of positional deviation is computed, thus calculating a third correction coefficient for correcting the positional deviation (step S206). The third correction coefficient is a correction coefficient for correcting positional deviation associated with an eddy current. Then, an evaluation pattern is written on another substrate 101 using the first to third correction coefficients while the XY stage is being moved (continuous writing) (step S207). The resist is not coated with CDL. The evaluation pattern is written in as wide a range of the writable area of the substrate 101 as possible. After the evaluation pattern is written, development is performed to form a resist pattern. Then, the metal light-shielding layer is etched by using the resist pattern as a mask, the resist is removed, and cleaning is performed, thus forming a light-shielding-layer pattern. The position of the light-shielding-layer pattern is measured and the amount of positional deviation is computed, thus calculating a fourth correction coefficient for correcting the positional deviation (step S208). The fourth correction coefficient is a correction coefficient for correcting positional deviation associated with substrate flexure. As described above, the calculated correction coefficients can be sequentially used to obtain the correction coefficients for correcting positional deviation or errors associated with physical phenomena. In the present embodiment, it is preferred that writing in a small writing area (central part of the substrate) be performed prior to writing in a wide range of the writing area to calculate or update correction coefficients. In addition, it is preferred that static writing, in which writing is performed while the XY stage 105 is being stopped, be performed prior to continuous writing, in which writing is performed while the XY stage 105 is being moved, to calculate or update correction coefficients. FIG. 6 is a flowchart explaining a method of determining correction coefficients for various substrate materials and writing conditions and performing writing on a product. An electron beam is scanned over a reference mark disposed at a different position from a substrate placement area of the XY stage 105, electrons reflected from the reference mark are detected, and an optical system or tracking of the XY stage 105 is adjusted based on the result of scanning to eliminate distortion in shape of deflection fields (step S301). In this step, writing is not performed on a substrate 101. The writing apparatus can therefore be adjusted without being affected by substrate materials. Then, an evaluation pattern is statically written in central part of a substrate 101 having CDL applied to the resist (step S302). After the evaluation pattern is written, development is performed to form a resist pattern. Then, the metal light-shielding layer is etched by using the resist pattern as a mask, the resist is removed, and cleaning is performed, thus forming a light-shielding-layer pattern. The position of the light-shielding-layer pattern is measured and the amount of positional deviation is computed, thus determining a first correction coefficient for correcting the positional deviation (step S303). The first correction coefficient is a correction coefficient for correcting positional deviation associated with field distortion that failed to be eliminated by adjusting the optical system in step S301. If positional deviation associated with resist charging is to be corrected (Yes in step S304), an evaluation pattern is statically written in central part of another substrate 101 having no CDL using the first correction coefficient obtained in step S303 (step S305). A plurality of substrates 101 having different types of resist are prepared, and the evaluation pattern is written on each of the substrates 101. After the evaluation pattern is written, development is performed to form a resist pattern. Then, the metal light-shielding layer is etched by using the resist pattern as a mask, the resist is removed, and cleaning is performed, thus forming a light-shielding-layer pattern. The position of the light-shielding-layer pattern is measured and the amount of positional deviation is computed, thus calculating a second correction coefficient for correcting the positional deviation (step S306). The second correction coefficient is a correction coefficient for correcting positional deviation associated with resist charging. The type of resist is a parameter. If the correction of positional deviation associated with resist charging is not needed (No in step S304) because, for example, CDL is set to be used in writing on a product, CDL is applied to the substrate in the subsequent writing to prevent resist charging (step S307). Then, an evaluation pattern is written in central part of another substrate 101 while the XY stage is being moved (continuous writing) (step S308). The effect of resist charging is eliminated by using the first and second correction coefficients or by applying CDL to the resist and using the first correction coefficient. A plurality of substrates 101 including different metal light-shielding layers made of different materials are prepared. The evaluation pattern is written on each of the substrates 101 while the moving speed of the XY stage 105 is being changed for each substrate. After the evaluation pattern is written, development is performed to form a resist pattern. Then, the metal light-shielding layer is etched by using the resist pattern as a mask, the resist is removed, and cleaning is performed, thus forming a light-shielding-layer pattern. The position of the light-shielding-layer pattern is measured and the amount of positional deviation is computed, thus calculating a third correction coefficient for correcting the positional deviation (step S309). The third correction coefficient is a correction coefficient for correcting positional deviation associated with an eddy current. The material of the metal light-shielding layer and the moving speed of the XY stage 105 are parameters. For example, the third correction coefficient is expressed by an approximate expression that approximates the amount of positional deviation (correction amount) using the moving speed of the stage as a factor. Then, while the XY stage is being moved, an evaluation pattern is written on another substrate 101 using the first to third correction coefficients or on another substrate 101 having CDL applied to the resist using the first and third correction coefficients (continuous writing) (step S310). The evaluation pattern is written in as wide a range of the writable area of the substrate 101 as possible. After the evaluation pattern is written, development is performed to form a resist pattern. Then, the metal light-shielding layer is etched by using the resist pattern as a mask, the resist is removed, and cleaning is performed, thus forming a light-shielding-layer pattern. The position of the light-shielding-layer pattern is measured and the amount of positional deviation is computed, thus calculating a fourth correction coefficient for correcting the positional deviation (step S311). The fourth correction coefficient is a correction coefficient for correcting positional deviation associated with substrate flexure. When an electron beam is applied to the substrate 101 in the electron beam writing apparatus, reflected electrons occur. The reflected electrons may strike the optical system and the detector in the electron beam writing apparatus, causing a charge-up phenomenon. In such a case, a new electric field is generated from a place affected by the charge-up phenomenon. Furthermore, the material of the resist irradiated with the electron beam may be scattered, and the deflectors may be contaminated with the scattered resist material. These factors may cause the trajectory of the electron beam to change with time, causing the beam to drift such that a writing position is deviated from a desired position. If beam drift occurs (No in step S312), the position of the reference mark on the stage is detected and the amount of drift is properly measured, thus correcting the writing position (step S313). Information about a substrate, serving as a product, and writing conditions are registered in the writing apparatus (step S314). In writing on the product (step S315), the correction coefficients for the material of the metal light-shielding layer included in the substrate 101, serving as a writing target, the type of resist, and the moving speed of the stage in the writing operation are read from the memory 142, a writing position is corrected using the correction coefficients, and a predetermined pattern is written. The positional deviation or errors resulting from the physical phenomena can be corrected, thus improving the writing positional accuracy. Although the configuration using an electron beam has been described in the above embodiments, the present invention is not limited to such an example. The present invention is applicable to a configuration using another charged particle beam, such as an ion beam. Although the single-beam writing apparatus has been described in the above embodiments, a multi-beam writing apparatus may be used. While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms, furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.
	summary
	summary
	claims	1. A system for phase stepping in phase contrast image acquisition, the device comprising:a phase contrast image acquisition apparatus including a radiation source; anda device comprising:a mobile grating spaced apart, in an optical axis direction of a radiation emitted from the radiation source, from the radiation source, wherein the mobile grating is movable along a linear direction different from the optical axis direction;a guide,wherein when the mobile grating is moving along the linear direction different from the optical axis direction, the guide is configured to guide the mobile grating between a first position and a second position and along the linear direction different from the optical axis direction, andwherein the first position is offset from the second position in the linear direction different from the optical axis direction;a restorer configured to apply a force to the mobile grating, the force being directed from the first position to the second position; anda lock configured to releasably lock the mobile grating in the first position. 2. The system according to claim 1, wherein the device further comprises:a position decoder configured to detect a position of the mobile grating along the guide and emit a trigger signal for a detector if the mobile grating passes predefined positions along the guiding element guide. 3. The system according to claim 1, wherein the mobile grating is configured to perform a continuous movement between the first position and the second position. 4. The system according to claim 1, wherein the device further comprises:a movement dampener configured to dampen a movement of the mobile grating between the first position and the second position. 5. The system according to claim 4, wherein the movement dampener is controllable. 6. The system according to claim 4, wherein the movement dampener applies at least an under critical dampening to the movement of the mobile grating. 7. The system according to claim 1, wherein the device further comprises:a mobile grating mover configured to move the mobile grating into the first position. 8. The system according to claim 1,wherein the phase contrast image acquisition apparatus comprisesat least one immobile grating; andwherein a movement of the mobile grating from the first position to the second position shifts the mobile grating relative to the at least one immobile grating. 9. The system according to claim 1, wherein the phase contrast image acquisition apparatus comprises:a detector that includesa photodiode array; anda scintillator;wherein the photodiode array matches the scintillator; andwherein the detector is configured to completely read out the photodiode array at least four times during a movement of the mobile grating between the first position and the second position. 10. A method for phase stepping in phase contrast image acquisition, the method comprising:locking a mobile grating in a first position with a lock,wherein the mobile grating and a radiation source are spaced apart from each other in an optical axis direction of a radiation emitted from the radiation source,wherein the mobile grating is movable between the first position and a second position and along a linear direction different from the optical axis direction of the radiation, andwherein the first position is offset from the second position in the linear direction different from the optical axis direction;applying a force on the mobile grating with a restorer, wherein the force is directed from the first position to the second position; andunlocking the lock such that the force moves the mobile grating into the second position. 11. The method according to claim 10, further comprising:reading out a detector on which X-ray radiation passing the mobile grating falls on.
	description	This application is a continuation of U.S. patent application Ser. No. 11/517,622, filed Sep. 8, 2006, now U.S. Pat. No. 8,003,934 which is a continuation-in-part of U.S. patent application Ser. No. 11/063,485, filed Feb. 22, 2005, now U.S. Pat. No. 7,138,642 which claims the benefit of U.S. Patent Application Ser. No. 60/547,259, filed Feb. 23, 2004. This application is also a continuation-in-part of U.S. patent application Ser. No. 11/063,801, filed Feb. 22, 2005, now abandoned which claims the benefit of U.S. Patent Application Ser. No. 60/547,302, filed Feb. 23, 2004, and U.S. Patent Application Ser. No. 60/619,113, filed Oct. 15, 2004. This application further claims priority to U.S. Patent Application Ser. No. 60/798,377, filed May 5, 2006, and U.S. Patent Application Ser. No. 60/802,941, filed May 23, 2006. In addition, this application is related to the following three U.S. patent applications filed Sep. 7, 2006: (1) U.S. patent application Ser. No. 60/843,105 entitled “Advanced ion source for macromolecules;” (2) U.S. patent application Ser. No. 60/843,106 entitled “Ion source with controlled liquid injection;” and (3) U.S. patent application Ser. No. 60/843,205 entitled “Computer controlled active feedback system for LDI/ES ion source with electro-pneumatic superposition.” All aforementioned applications are incorporated herein by reference in their entirety. This invention is in the field of chemical and biochemical analysis, and relates particularly to methods and apparatus for controlling and improving ion current in an ion transmission device in a mass spectrometer apparatus. The sensitivity of an ion analytical instrument, such as a mass spectrometer, depends in part upon the efficiency with which the coupled ion source generates ions from the analytical sample and then delivers those ions to the instrument for analysis. Matrix Assisted Laser Desorption and Ionization (MALDI)/Laser Desorption Ionization (LDI) and Electrospray ion sources have become an essential and enabling building block in modern mass spectrometry of biological macromolecules (e.g. proteins, peptides and sugars etc.). Both methods were awarded the Nobel Prize in Chemistry in 2002 and revolutionized the application of mass spectrometers in life science, in particular in proteomics but also in functional genomics and metabolomics and drug discovery. One of the ultimate goals of life science (including disciplines such as proteomics) is the prediction of disease based on molecular information. To achieve this goal, highly efficient and sensitive ion sources as well as mass spectrometers with sufficient mass accuracy and reliability have to be available. Highly sensitive ion sources are needed in view of factors such as the following: 1. The human proteome is estimated to contain >106 protein species. 2. These proteins are thought to occur at an extremely large range of abundance (≈1010). 3. Typically purification/selective binding are required which further reduces sample abundance. 4. Many purification methods impact ionization efficiencies negatively. 5. Frequently only very small sample amounts in low concentrations are available (mg or less, a few 103 cells). 6. Investigations face combinatorial complexity from factors such as the very high number of measurements required, and the fact that Investigations limited by time. It can be assumed that the discovery of biomarkers and the ability to predict diseases is currently hindered and limited by the unreliability with which distinctive patterns in mass spectra can be found, at least partially as a result of imperfections and limitation of the current ion source technology. This is one of the remaining obstacles for mass spectrometry to move from being an instrument in biochemical labs to an everyday tool in clinics and hospitals. Beside the application in life science and medicine, rapid and sensitive detection of organic and inorganic compounds will, unfortunately, become more common in the form of screening for biological agents and residues of explosives. One specific variant of MALDI is sometimes referred to as Surface Enhanced Laser Desorption Ionization (SELDI) in which the matrix is already pre-deposited on the target surface. We will henceforth refer to MALDI and SELDI commonly as MALDI, or in general, as LDI. Electrospray (ES) has a number derivatives or of what can be considered variants such as Electrohydrodynamic ionization, Aerospray ionization, ACPI, and Thermospray ionization and which shall also be considered as included in the following. Fundamentally, both LDI and ES methods suffer from a number of problems which limit their practical application, including aspects such as sensitivity, usefulness as quantitative tools, and usefulness in biomarker discovery. One significant problematic factor is that of molecular fragmentation. Due to the high laser power densities LDI/MALDI ion sources eject ions with substantial translational and internal temperatures which frequently results in molecular fragmentation and decay thereby limiting the available ion life time for analysis. Such ion fragmentation also reduces sensitivity and, importantly, reduces the ‘fidelity’ or clarity of mass spectra which limits or prevents further data analysis, e.g. for biomarker discovery and analysis: Correlation of data from mass spectra with medical conditions of living or dead, human, animal or plant subjects from which analyzed samples were taken. In MALDI ion sources typically a UV laser (sometimes IR) is fired at the crystals in the MALDI spot with typical pulse duration on the order of tLP≈10−9 to 10−8 s. The matrix molecules in the spot absorb the electromagnetic laser energy and are thought to protect the sample molecules. This, however, is only achieved to a very limited extent. Originally, LDI/MALDI ion sources have been operated under vacuum conditions at pressures where sample ion—background gas collisions are negligible. Later, ion sources operating at elevated pressure or Atmospheric Pressure MALDI (AP MALDI) have been introduced for convenience in terms of sample handling as well as collisional cooling. Experiments carried out in the early 90's indicated improved ion transmission within gas-filled multipole ion guides due to “collisional cooling”: Repeated collisions of ions with gas molecules reduce the temperature of the ions and also cause the ion beam to collapse axially inside RF multipole ion guides. This collisional cooling effect was subsequently utilized in MALDI ion sources themselves. Simple versions of so called elevated pressure and Atmospheric Pressure MALDI (AP MALDI) ion sources have been described beginning in the late '90. However, their ion-optical design is poor and a pneumatic design is effectively non-existent due to the lack of appropriate computational design tools capable of modeling the flow field as well as the electro-pneumatic interactions (ion-neutral collisions). A second significant problematic factor in conventional mass spectrometry involves inefficiency. LDI/MALDI is a highly inefficient means to generate ions from a sample which results in a general lack of sensitivity of this method as well as very poor performance in terms of true quantitative sample analysis. In addition, sample preparation techniques strongly influence the characteristics of the obtained mass-spectrometric data in a mostly unpredictable manner. In LDI/MALDI ion sources molecules in the sample spot absorb the electromagnetic laser energy and it is thought that primarily the matrix is ionized by this event. The matrix is then thought to transfer part of their charge to the analyte (e.g. a protein), thus ionizing them while (to a limited extent) still protecting them from the disruptive energy of the laser. Ions observed after this process are quasimolecular ions that are typically ionized by the addition of a proton to [M+H]+ or the removal of a proton [M−H]−. MALDI generally produces singly-charged ions, but multiply-charged ions such as [M+2H]2+ have been observed specifically in conjunction with IR lasers. However, if one thoroughly analyzes the budget of ions in a mass spectrometer it becomes apparent that the total ionization efficiency of MALDI is incredibly weak. For example, if a sample of 1 pmol (6·1023·10−12=6·1011) of stable biological macromolecules with a mass on the order of m=103 u is introduced into a commercially available high-end MALDI triple-quadrupole-Time-of-Flight (TOF) instrument an ion count on the order 104 can be expected. It is known that the total ion transmission efficiency of that particular type of mass spectrometer (including detector efficiency, duty cycle, quadrupole transmission etc.) is on the order of 10−2. This means that approximately only 106 ions are transmitted from the MALDI ion source into the mass spectrometer. Since the sample contains 6·1011 molecules the ionization efficiency is on the order of 106/6·1011≈1.6·10−6. Approximately only one sample molecule in one million becomes an ion and is transmitted into the mass spectrometer. Even if this approximation would underestimate the ionization efficiency by one order of magnitude it is still apparent that a fundamental shortcoming of state-of-the-art MALDI is the lack of ionization efficiency. Further improvements in mass spectrometer performance can be helpful but have by far less potential than improvements on the ion sources and aspects such as ionization efficiency. In conventional MALDI ion sources the available time for ionization is approximately only on the order of the duration of the laser pulse or slightly above (t≈101 ns). Thereafter, the plume expands and electrons and protons are rapidly extracted from the plume due their substantially lower mass-to-charge ratio m/q compared to sample ions of interest with a typical range of m/q≈102 u/e to 106 u/e. The creation and transfer of free charges to sample molecules in a conventional MALDI process can in fact be considered a byproduct. A third level of problematic considerations involve the electrospray process itself. In Electrospray ion sources a liquid, in which the sample molecules are dissolved, is pressed through a capillary. It is generally assumed that the sample molecules are already in an ionized state inside the liquid and upon leaving the capillary the liquid forms a mist (or aerosol) of very small droplets containing such ionized sample molecules (“nebulization”) which, due to coulombic forces, eventually releases individual ionized sample molecules of varying charge state. The exact mechanism of the ion formation is a matter of scientific debate. There are several fundamental problems in Electrospray ion sources. First, the nebulization and ionization depends on large number of parameters such as, sample concentration, degree of dissociation, liquid flow rate, liquid conductivity, liquid surface tension, capillary diameter, liquid pressure, electric field, gas flow fields, gas temperature fields, gas pressure fields, etc. Stable nebulization and ionization can be difficult to achieve. Moreover, a single or a plurality of droplets can not intentionally be created at a specific point in time with specific initial velocity and direction. Further The total ionization efficiency is also very low (although generally assumed to be better than conventional MALDI) since it depends to some extend on physical characteristics of the initial droplets and their creation, such as net charge, which are at least partially influenced by or in fact based on random processes/natural fluctuation. A fourth problem is that thus far ES ion source designs have been considerably suboptimal since the combined influence of the electric fields and gas flow fields has not been addressed with sufficient accuracy due to the lack of appropriate computational tools. A fifth level of problematic considerations involve operational limitations. Both advanced LDI and ES ion sources are inherently difficult to operate due to the complexity of the ion source behavior, the number of parameters that can be adjusted, and the limited available time during measurements. A typical user of such ion sources (connected to mass spectrometers) can not be expected to perform such correcting adjustments in an optimal and rapid fashion. Thus there is a need to address this problem by providing an automated, active control and feedback system which performs the desired operations. Aspects of the present invention provide methods, apparatus, systems, processes and other inventions relating to: ion sources with controlled electro-pneumatic superposition, ion source synchronized to RF multipole, ion source with charge injection, optimized control in active feedback system, radiation supported charge-injection liquid spray, and ion source with controlled liquid injection, as well as various embodiments and combinations of each of the foregoing. The disclosed inventions address these and other problems by providing the following solutions. Disclosed herein are ion sources based controlled superposition of electric and pneumatic fields which enables extraordinary performance in terms of ion survivability and ion guidance and transmission. In contrast to state-of-the-art devices, gas pressure and gas flow velocities are not considered as global quantities but as spatially distributed fields. In this new class of ion optical electro-pneumatic devices, the balance between electrical and collisional forces on ions varies spatially in a controlled fashion by utilizing elements which act as electrodes and have also aerodynamic functionality, i.e. “electro-pneumatic elements.” Disclosed herein is a method to increase total ion transmission from ion sources based on controlled superposition of electric and pneumatic fields whereby the operation of the ion source is synchronized to the operation of a RF multipole to which the ion source transmitting ions and the RF multipole using ramped or stepped mass ranges. Disclosed herein are LDI/MALDI ion sources with Charge-Injection. Such Charge-Injection LDI/MALDI (CIN-LDI/CIN-MALDI) ion source technology achieves orders of magnitude higher sample ionization efficiency by exposing the ejected neutral sample molecules to a controlled and directed low energy charge injection ion beam of stable low molecular weight ions (including protons) originating from an ion gun with specific kinetic energy. Disclosed herein are ion sources wherein at a single or a plurality of droplets containing sample molecules (1) a low energy charge injection ion beam of stable low molecular weight ions (including protons) originating from an ion gun is controlled and directed with specific kinetic energy and (2) a beam of electromagnetic radiation is directed. The fundamental advantage of this configuration is that it allows to substantially increase the net charge state of the droplet(s) as well as their temperature/evaporation rate, effectively independent of an energy transfer with a optionally present background gas. Disclosed herein are ion sources wherein the droplet formation of liquids or liquid crystals containing sample molecules is largely independent of the pressure and rate with which the liquid is supplied, the degree of dissociation of the sample molecules, the electric conductivity of the liquid, and the electric field at the capillary tip from which the droplets are released. Such ion sources enable electrically controlled formation and ejection of droplets of specific size and with specific initial velocity. Disclosed herein is a method of optimizing the operation of an ion source utilizing electro-pneumatic superposition, the source being in ion communication with a mass spectrometer, wherein an active control system analyzes data generated during operation of the mass spectrometer and active control system derives and generates signals from the data analysis, and providing these signals as feedback to control the operation of the ion source. Ion Sources with Controlled Electro-Pneumatic Superposition Aspects of the present invention provide apparatus and methods in which controlled superposition of gas flow fields and electrostatic fields within an ion source can effect rapid collisional cooling with improved collection, collimation, and output of ions, as well as other effects. The high efficiency injection of unfragmented ions into ion analytical instruments to which the source may be operably coupled can increase significantly the sensitivity of the analytical apparatus. In one aspect, the invention provides a device for outputting ions, an ion source device. In some embodiments, the device may comprise a first housing and a second housing. In such embodiments, the first housing may comprise at least one pneumatic element that segregates the space within the first housing into a gas reservoir and an ion expansion chamber, the gas reservoir being in axisymmetric gas communication with the ion expansion chamber and in gas communication with the exterior of the first housing. A second housing of such embodiments may comprise at least one pneumatic element that segregates the space within the second housing into an axial trajectory region and a gas sink region, the gas sink region being in axisymmetric gas communication with the axial trajectory region and in gas communication with the exterior of the second housing. The first housing expansion chamber of some embodiments may be axially aligned with and in gas and ion communication with the second housing axial trajectory region; the second housing axial trajectory region may be in axial alignment with and in ion communication with an ion outlet of the device. In some embodiments the elements, including electro-pneumatic elements, within the first and second housing may not be axisymmetric or may be only partially axisymmetric. In some embodiments they may be generally axisymmetric. Ions introduced into or generated within the ion expansion chamber may be guided, during operation of the device, along the device axis from the expansion chamber through the axial trajectory region to the ion outlet predominantly by pneumatic fields in the first housing and predominantly by electrostatic fields in the second housing. In some embodiments, the first housing may comprise a plurality of pneumatic elements that segregate the space within the first housing into a gas reservoir and an ion expansion chamber, the gas reservoir being in axisymmetric gas communication with the ion expansion chamber and in gas communication with the exterior of the first housing. Similarly, the second housing may comprise a plurality of pneumatic elements that segregate the space within the second housing into an axial trajectory region and a gas sink region, the gas sink region being in axisymmetric gas communication with the axial trajectory region and in gas communication with the exterior of the second housing. In order to generate superposed pneumatic and electrostatic fields in a first portion of the ion trajectory, the first housing may further comprise at least one electrically conductive element; at least a portion of at least one of the first housing pneumatic elements may be electrically conductive. In some embodiments, at least a portion of a plurality of the first housing pneumatic elements may be electrically conductive. In a subset of these embodiments, each of the plurality of first housing pneumatic elements may be electrically conductive. The first housing electrically conductive elements, if present, may be capable of creating an electrostatic field that is capable of affecting ion trajectory in the expansion chamber. In order to generate superposed pneumatic and electrostatic fields in a second portion of the ion trajectory, the second housing may further comprise at least one electrically conductive element. In some embodiments, at least a portion of at least one of the second housing pneumatic elements may be electrically conductive. Often, at least a portion of a plurality of the second housing pneumatic elements may be electrically conductive. In a subset of these latter embodiments, each of the plurality of second housing pneumatic elements may be electrically conductive. The second housing electrically conductive elements, when present, may be capable of creating an electrostatic field capable of guiding ions axially through the axial trajectory region to a device outlet that communicates the axial trajectory region with the exterior of the second housing. The ion source device of the present invention may include means for introducing ions into or generating ions within the expansion chamber. The means can, for example, comprise engagement means or guides for a laser desorption ionization probe upon which an analytical sample may be disposed, the engagement means being capable of positioning a laser desorption ionization probe so as to display at least one surface thereof to the expansion chamber. In some of these embodiments, the probe engagement means may be in physical and electrical contiguity to an electrically conductive element. The engagement means may include a probe holder, or other suitable device known in the art. In addition, the first housing may comprise at least one symmetrically disposed gas inlet, typically a plurality of separately disposed gas inlets, that communicate the gas reservoir with the exterior of the first housing. The gas inlet(s) may be so shaped and so disposed that the gas pressure inside the gas reservoir is, for the most part, spatially constant, and on average only negligible gas flow speeds occur inside the gas reservoir as compared to gas flow speeds in the expansion chamber. In some embodiments, for example, the gas inlets may comprise means to baffle inward streaming gas flow to facilitate the achievement of such pressure and flow characteristics. Analogously, the second housing may comprise at least one, typically a plurality of, symmetrically disposed gas outlets that communicate the gas sink region with the exterior of the second housing. In some embodiments, one or two completely open sides of the second housing may act as the gas outlets. In various embodiments, the second housing may further comprise additional gas flow guiding means (pneumatic elements) which help maintain axisymmetrically outwardly directed gas flow out of the sink region, although at some point during the spatial transition from the gas sink region to the exterior of the second housing, spatial symmetry may be broken. Typically, the collective gas flow resistance of the gas outlets is lower than the collective gas flow resistance of the gas inlets. In some embodiments, the plurality of gas outlets may be communicably connected to means, disposed outside the second housing, for adjusting outward gas flow. In some embodiments, the plurality of gas inlets may be communicably connected to means, disposed outside the first housing, for adjusting inward gas flow. In certain embodiments, one or more of the at least one first housing pneumatic elements may be so shaped and so disposed that maximal constriction to axisymmetric gas flow between the gas reservoir and expansion chamber is located proximal to the expansion chamber. The gas communication between the gas reservoir and expansion chamber can be either continuously or periodically axisymmetric. The first and second housings can be separately constructed, and sealingly engaged, or of integral construction. In some embodiments, the ion source device can be operably coupled to an ion analytical instrument. In some embodiments, the ion source device may be so coupled to the analytical instrument as to permit gas to be evacuated through the second housing gas outlets from the ion analytical instrument's ion source-proximal region, such as from a multipole in the instrument's ion-source proximal region. The present invention further provides, in another aspect, an ion source device. The device may comprise ion generating means, first ion guidance means, and second ion guidance means. The first ion guidance means may be configured to establish electrostatic fields and ion-guiding pneumatic fields, the ion-guiding pneumatic fields predominating over electrostatic fields during use; the second ion guidance means may be configured to establish ion-guiding electrostatic fields and pneumatic fields, the ion-guiding electrostatic fields predominating over pneumatic fields during use. During operation, ions generated by the ion generating means may be guided by the pneumatically dominant first ion guidance means and then by the electrostatically dominant second ion guidance means along the device axis to a device outlet. The first ion guidance means of some embodiments may be disposed in a first housing, the second ion guidance means in a second housing, the first housing being in axial ion and gas flow communication with the second housing. As noted above, and further described herein below, the first and second housings can be of integral construction. In some embodiments, the first ion guidance means may comprise at least one electropneumatic element, the at least one electropneumatic element segregating the space within the first housing into a gas reservoir and an ion expansion chamber, the gas reservoir being in axisymmetric gas communication with the ion expansion chamber. In some of these embodiments, the first ion guidance means may comprise a plurality of electropneumatic elements, the plurality of electropneumatic elements segregating the space within the first housing into a gas reservoir and an ion expansion chamber, the gas reservoir being in axisymmetric gas communication with the ion expansion chamber. In some embodiments, at least one of the electropneumatic elements may be so shaped and so disposed within the first housing as to create radially inwardly-directed axisymmetric gas flow when the gas reservoir is at a higher pressure than the expansion chamber. In a subset of these embodiments, each of the electropneumatic elements may be so shaped and so disposed within the first housing as to create radially inwardly-directed axisymmetric gas flow when the gas reservoir is at a higher pressure than the expansion chamber. In certain embodiments, at least one of the electropneumatic elements may be so shaped and so disposed that gas flowing radially inwardly from the gas reservoir to the expansion chamber encounters maximal constriction axisymmetrically proximal to the expansion chamber. In some embodiments, the second ion guidance means may comprise at least one electropneumatic element, the at least one electropneumatic element segregating the space within the second housing into an axial trajectory region and a gas sink region, the axial trajectory region being in axisymmetric gas communication with the gas sink region. In a subset of these embodiments, the second ion guidance means may comprise a plurality of electropneumatic elements, the plurality of electropneumatic elements segregating the space within the second housing into an axial trajectory region and a gas sink region, the axial trajectory region being in axisymmetric gas communication with the gas sink region. At least one, often each of a plurality, of the electropneumatic elements may be so shaped and so disposed within the second housing as to create radially outward-directed axisymmetric gas flow when the axial trajectory region is at a higher pressure than the gas sink region. In some embodiments, the second ion guidance means may further comprise gas flow guiding means (pneumatic elements) that help maintain axisymmetrically outwardly directed gas flow out of the sink region, although at some point during the spatial transition from the gas sink region to the exterior of the second housing spatial symmetry may be broken. The first housing may comprise at least one, typically a plurality of, symmetrically disposed gas inlets that communicate the gas reservoir with the exterior of the first housing, and the second housing may comprise at least one large gas outlet, typically a plurality of gas outlets, that communicate the gas sink region with the exterior of the second housing, with the collective gas flow resistance of the second housing gas outlets being lower than the collective gas flow resistance of the first housing gas inlets. In some embodiments, the means for introducing or generating ions acts to generate ions within the expansion chamber. Such ion-generating means may include, in some embodiments, laser desorption ionization means. The laser desorption ionization means can comprise laser desorption ionization probe engagement means, the engagement means being capable of positioning a laser desorption ionization probe so as to display at least one surface thereof to the expansion chamber. In some of these embodiments, the probe engagement means may be in electrical contiguity with an electrically conductive element within the first housing. In some laser desorption ionization means, the laser desorption ionization means can further comprise a mirror that directs laser light to the surface of a laser desorption ionization probe substantially along the device axis. This mirror may also allow observation of the sample, such as by video or other optical systems. Alternatively, the laser desorption ionization means may include a first mirror that directs laser light to the probe surface, and may further include one or more additional mirrors that may be used for video or optical observation of the sample on the probe. In a further aspect, the invention provides analytical apparatus, comprising an ion source device according to the present invention, operably coupled to an ion analytical instrument. The ion analytical instrument can, in some embodiments, comprise at least one multipole radio-frequency (RF) ion guide, such as a quadrupole ion guide. In some of these embodiments, the operative coupling of the ion source device to the ion analytical instrument permits the ion source device to draw gas proximally outward from the RF multipole during use. The ion analytical instrument can usefully comprise at least one mass analyzer, and even a plurality of mass analyzers. In another aspect, the invention provides methods of increasing the collimated output of ions from an ion source device, and thus methods of increasing the sensitivity of ion analytical instruments to which such ion source devices may optionally be operably coupled. The methods comprise guiding ions introduced into or generated within the source along the device axis to an ion source outlet using superposed electrostatic and axisymmetric pneumatic fields. Ion-guiding pneumatic fields predominate in their effects on ion motion over electrostatic fields in a first portion of the ion trajectory and ion-guiding electrostatic fields predominate in their effects on ion motion over pneumatic fields in a second portion of the ion trajectory. In some embodiments, the pneumatic fields may be generated by establishing radially-inward axisymmetric and radially-outward axisymmetric gas flows in axial succession. In such embodiments, the ion source device can usefully be an ion source device of the present invention. In some of these embodiments, the magnitude of the gas flows may be controlled in part by controlling gas flows into the gas reservoir, and/or by controlling gas flows out of the gas sink region. In some embodiments, controlling gas flows out of the gas sink region may comprise controlling outwardly directed pumping of gas from the gas sink region. In embodiments of the methods of this aspect of the invention, electrostatic fields may be generated by applying an electrical potential to each of a plurality of electrically conductive elements in the ion source device. In some embodiments, the potential applied to at least one of the plurality of electrically conductive elements may change, typically under computer control, between the time of ion introduction into or generation within the device and ion output from the ion source device. In a subset of these embodiments, the potential applied to a plurality of electrically conductive elements may change between the time of ion introduction into or generation within the device and ion output from the ion source device. Such change in potential can be used to facilitate ion focusing and guidance. Such change in potential can also be used to facilitate injection of ions into an RF multipole of an analytical instrument that is optionally coupled to the ion source device. In the latter case, the potential applied to at least one of the plurality of the electrically conductive elements may be ramped coordinately with AC potential stepping of an RF multipole of an ion analytical instrument to which the source is operably coupled. The methods of the present invention may further comprise a subsequent step of performing at least one analysis on at least one species of ion output from the ion source device. For example, the analysis may comprise determining the mass to charge ratio of at least one ion species. The methods of the present invention may, other embodiments, further comprise the subsequent steps of: selecting at least one ion species output from the ion source device; fragmenting the at least one selected ion species; and performing at least one analysis on at least one product ion resulting from fragmenting the at least one selected ion. The analysis may, for example, be determining the mass to charge ratio of the at least one product ion, or performing a complete product ion scan. The methods of the present invention may further comprise, before the step of guiding ions to the ion source device outlet, the step of: introducing ions into or generating ions within the ion source device. Introducing or generating ions may comprise, in certain embodiments, generating ions by laser desorption ionization of an analytical sample. In certain of these embodiments, the analytical sample may comprise proteins, and the ions to be guided are ions generated from the proteins. In such embodiments, the methods may further comprise the antecedent step, before generating ions, of capturing proteins from an inhomogeneous mixture on a surface of a laser desorption ionization probe. Ion Source Synchronized to RF Multipole Aspects of the present invention also relate to the field of chemical and biochemical analysis, and relate to methods and apparatus for controlling and improving ion current in an ion transmission device in a mass spectrometer apparatus. The present invention solves these and other needs by providing an apparatus with an ion source and an ion transmission device, wherein the ion source and the ion transmission device are in ion communication. The ion current of the ion source may be controlled by coordination of the operating parameters of the ion source with the operating parameters of the ion transmission device. In a first aspect, the present invention provides a method for controlling the ion current of an ion transmission device by coordinating the respective operating parameters of the ion transmission device with the ion source. In another aspect, a method of the present invention is a method for controlling the ion current of an ion transmission device, wherein an ion source is in ion communication with and provides ions to the ion transmission device, the method may comprise coordinating a value for each of at least one operating parameter of the ion source with a value for each of at least one operating parameter of the ion transmission device. The step of coordinating may include setting the ion source operating parameters with values that are predetermined, or selected from a set of predetermined values. The predetermined values for the ion source operating parameters may be predetermined for providing ions of a given mass range from the ion source to the ion transmission device. The predetermined values for the ion source operating parameters may also be predetermined to provide ions of all mass ranges from the ion source to the ion transmission device. In certain embodiments, an apparatus of the present invention or methods practiced therewith may include an ion transmission device that provides ions to a mass spectrometer, an ion mobility spectrometer, or a total ion current measuring device. In certain embodiments, the step of coordinating may comprise setting values of the ion transmission device operating parameters and the ion source operating parameters, wherein the both of the respective values are predetermined for the given mass range of ions. In certain embodiments, the step of coordinating may comprise setting a first set of values of the ion transmission device operating parameters and setting a first set of values of the ion source operating parameters, wherein said first set of values for the ion source are predetermined based on the first set of values of the ion transmission device operating parameters. In certain embodiments, this method may further comprise the steps of setting a second set of values of the ion transmission device operating parameters and setting a second set of values of the ion source operating parameters, wherein said second set of values for the ion source are predetermined based on the second set of values of the ion transmission device operating parameters. In certain embodiments, the step of coordinating may comprise determining the values of the ion transmission device operating parameters and then setting values of the ion source operating parameters, wherein said values for the ion source are predetermined based on the values determined for the ion transmission device operating parameters. In certain embodiments, an apparatus of the present invention or methods practiced therewith may include an ion transmission device that may comprise a multipole radio-frequency ion guide. In such embodiments, examples of ion transmission device operating parameters include the amplitude and frequency of the alternating current potential of the multipole ion guide electrodes. Ion transmission device operating parameters may also include the amount of DC potential that may be applied to the multipole radio-frequency ion guide with the AC potential. In certain embodiments, an apparatus of the present invention or methods practiced therewith may include an ion transmission device that may comprise an electrostatic ion guide or an electromagnetic ion guide. In certain embodiments, an apparatus of the present invention or methods practiced therewith may include an ion source that may comprise a laser desorption/ionization ion source, a chemical ionization ion source, an electron impact ionization ion source, a photoionization ion source or an electrospray ionization ion source. These and other suitable ion sources known in the art, such as other known methods of generating ions from an analyte sample, may be used with or included in the present invention. In certain embodiments, an apparatus of the present invention or methods practiced therewith may include an ion source that may comprise at least one electrode capable of affecting the potential experienced by ions in the ion source. In certain embodiments, at least one of the ion source operating parameters includes the direct current potential of at least one of the ion source electrodes. In certain embodiments, at least one of the ion source operating parameters includes an alternating current potential of at least one of the ion source electrodes. In certain embodiments of the present invention, the step of coordinating may comprise setting values of the ion transmission device operating parameters and setting values of the ion source operating parameters, wherein at least one of the values of the ion source operating parameters is calculated based on at least one of the values of the ion transmission guide operating parameters. In certain embodiments, an apparatus of the present invention or methods practiced therewith may include an ion transmission device that may comprise a multipole radio-frequency ion guide, and at least one of the ion transmission guide operating parameters includes the amplitude and frequency of the radio-frequency alternating current potential of the multipole ion guide electrodes. In certain embodiments of the present invention, the step of coordinating may comprise monitoring in real-time at least one of the operating parameters of the ion transmission device. In certain embodiments of the present invention, the potential applied to the at least one of the electrodes of the ion transmission device may be monitored in real-time. In certain embodiments of the present invention in which the ion source and the ion transmission device are in signal communication with a controller, the step of coordinating may comprise configuring the controller to set at least one of the values of the ion source operating parameters, wherein said at least one set values are predetermined based on at least one of the values of the ion transmission device operating parameters as determined by the controller. In certain embodiments in which the ion source operating parameters are predetermined for a given mass range, the ion current may be improved for the given mass range. In certain embodiments, the given mass range may be user-defined. In certain embodiments of the present invention in which the ion source and the ion transmission device are in signal communication with a controller, the step of coordinating may comprise configuring the controller to set at least one of the values of the ion source operating parameters, wherein said at least one set values are predetermined based on a given mass range. In certain embodiments of the present invention, the given mass range is user-defined. In certain embodiments of the present invention in which the ion source and the ion transmission device are in signal communication with a controller, the step of coordinating may comprise configuring the controller to set at least one of the values of the ion source operating parameters, wherein the at least one of said set values are calculated based on at least one of the values of the ion transmission device operating parameters. In certain embodiments of the present invention in which the ion source and the ion transmission device are in signal communication with a controller, the step of coordinating may comprise configuring the controller to set at least one of the values of the ion source operating parameters, wherein said at least one set values are predetermined for a given mass range of ions, and whereby the controller is capable of coordinating the respective values of the operating parameters of the ion source and the ion transmission device for the given mass range. In certain embodiments of the present invention in which the ion source and the ion transmission device are in signal communication with a controller, the step of coordinating may comprise configuring the controller to set at least one of the values of the ion source operating parameters, wherein at least one of said set values are calculated based on at least one of the values of the ion transmission device operating parameters, and whereby the controller is capable of coordinating the respective values of the operating parameters of the ion source and the ion transmission device. In certain embodiments of the present invention in which the ion source and the ion transmission device are in signal communication with a controller, the step of coordinating may comprise configuring the controller to set at least one of the values of the ion source operating parameters, wherein said at least one set values are based on the values of the ion transmission device operating parameters, and whereby the controller is capable of coordinating the respective values of the operating parameters of the ion source and the ion transmission device. In another aspect, the present invention provides an apparatus for controlling the ion current of an ion transmission device therein. An apparatus of the present invention may comprise an ion source, an ion transmission device in ion communication therewith, and a controller configured to coordinate respective values of the operating parameters of the ion source and the ion transmission device. In certain embodiments, the controller may comprise a digital computer and/or memory. In certain embodiments, the controller may be in signal communication with the ion source and the ion transmission device of the apparatus. In certain embodiments, the controller may be configured to coordinate the value of at least one ion source operating parameter with the value of at least one ion transmission device operating parameter. In certain embodiments of the apparatus, the controller, when coordinating the respective values of the operating parameters, may be configured to determine at least one of the values of the ion transmission device operating parameters and set at least one of the values of the ion source operating parameters, wherein the values set for the ion source operating parameters are selected from a set of predetermined values based on the values determined for the ion transmission device operating parameters. In some embodiments, the controller may comprise memory in which the set of predetermined values are stored. In certain embodiments of the apparatus, the controller, when setting the values of the ion source operating parameters, may be configured to calculate at least one of the values of the ion source operating parameters, wherein said calculation is based on at least one of the values of the ion transmission device operating parameters. In certain embodiments of the apparatus, the controller, when coordinating the respective values of the operating parameters, may be configured to set at least one of the values of the ion transmission device operating parameters and set at least one of the values of the ion source operating parameters, wherein said set values of the ion source operating parameters are predetermined for providing ions of a given mass range from the ion source to the ion transmission device. In certain embodiment, the given mass range may be user-defined. In certain embodiments of the apparatus, the ion source may be a laser desorption/ionization ion source, a chemical ionization ion source, an electron impact ionization ion source, a photoionization ion source, an electrospray ionization ion source, or a plasma desorption ion source. In certain embodiments of the apparatus, the ion source may comprise at least one electrode capable of affecting the potential experienced by ions in the ion source. The ion source operating parameters may include the magnitude of a direct current potential of at least one of the ion source electrodes. The ion source operating parameters may also include the frequency and amplitude of an alternating current potential of at least one of the ion source electrodes. In certain embodiments of the apparatus, the ion transmission device may comprise a multipole radio-frequency ion guide. The ion transmission device operating parameters may include the amplitude of a radio-frequency alternating current potential of the multipole radio-frequency ion guide electrodes. The multipole radio-frequency ion guide may include a quadrupole ion guide, a hexapole ion guide, or an octopole ion guide. In certain embodiments of the apparatus, the ion source may comprise systems and components for providing a gas flow field, such as are known in the art. In certain embodiments, the apparatus may further comprise one or more mass analyzers. Suitable mass analyzers may include a quadrupole mass filter, a reflectron, a time-of-flight mass analyzer, an electric sector time-of-flight mass analyzer, a triple quadrupole apparatus, a Fourier transform ion cyclotron resonance mass analyzer, a magnetic sector mass analyzer, or other suitable mass analyzers known in the art. It is understood that the present invention embraces embodiments in which the apparatus does not include a mass analyzer component with the ion source and ion transmission device. In some embodiments, the apparatus may be a tandem mass spectrometer. In certain embodiments of the apparatus, one or mass analyzers may be in ion communication with the ion transmission device. The mass analyzer may be disposed at either the entry or the exit of said ion transmission device. In some embodiments, one or more optional intervening components may be disposed between the ion transmission device and the mass analyzer, wherein the optional intervening component may allow and/or facilitate ion communication between the mass analyzer and the ion transmission device. In certain embodiments of the apparatus, the ion transmission device may include a mass analyzer. For example, in some embodiments the apparatus of the present invention may comprise an ion source in ion communication with an ion transmission device, wherein the ion transmission device is a mass analyzer. In other embodiments, the ion transmission device may include one or more mass analyzers and one or more ion guides, such as a multipole ion guide. In these embodiments, the mass analyzer and the ion guide function together as an ion transmission device. In certain embodiments, the apparatus may further comprise an ion current measuring device or an ion mobility spectrometer. The apparatus may also further comprise an ion detector. In still another aspect, the present invention provides an apparatus that includes an ion source in ion communication with an ion transmission device, and a system for coordinating the respective operating parameters of the ion source and the ion transmission device. In certain embodiments of the apparatus, the coordinating system may comprise a component for determining at least one of the values of the ion transmission device operating parameters. In certain embodiments of the apparatus, the coordinating system may comprise a component for setting at least one of the values of the ion source operating parameters, wherein at least one of the values set for the ion source operating parameters is based on at least one of the values determined for the ion transmission device operating parameters. In certain embodiments, the apparatus may further comprise a system for the mass analysis of ions, wherein the coordination system improves the sensitivity of said system for ion mass analysis. Charge Injection Aspects of certain embodiments of the inventive CIN-LDI/CIN-MALDI ion source system include a low energy charge injection ion beam (CIN-beam) of stable low molecular weight ions (including protons) originating from an ion gun, the ion beam being controlled and directed with specific kinetic energy by electric and/or magnetic fields into the plume of a laser pulse-desorbed sample containing sample ions and neutral sample molecules and/or onto the sample itself. Low energy collisions occur between neutrals and CIN-beam ions (CIN-ions) which attach to the neutral sample molecules thereby increasing the total sample ionization efficiency of the ion source and the sample ions then being extracted by electric fields. The system as a whole represents an optimized ion-optical and/or electro-pneumatic ion-optical configuration for high resolution mass spectrometry. In some embodiments, the ion gun may feed ions into an ion trap to accumulate CIN-ions which are then pulsed into the LDI/MALDI region. In some embodiments, the CIN-beam may be pulsed or modulated in a pulse-like arbitrarily time-dependent manner, synchronized with the laser and acceleration potentials on the electrodes in the CIN-LDI/CIN-MALDI ion source are turned off or floated during the CIN ion injection but turned on thereafter to extract created sample ions. In some embodiments, the initial kinetic energy of the CIN-ions may be sufficient to reach the sample target with CIN-ion—sample interaction predominately occurring at the sample surface or its immediate proximity. In some embodiments the initial kinetic energy of the CIN-ions may be insufficient to reach the sample target, causing them to reverse their trajectories thereby largely increasing the collision probability with neutrals thereby having most of the ionization of the neutral sample molecules occurring in a region adjacent to the sample. In various embodiments, the CIN-beam may be either DC or pulsed. In some of the pulsed embodiments, the pulsed CIN-beam is synchronized to the MALDI laser(s) pulse(s). In some embodiments with several CIN-beam pulses, the pulses are similarly synchronized to the MALDI laser(s) pulse(s) Some embodiments of the inventive CIN-LDI/CIN-MALDI ion source system may operate with pulsed or arbitrarily time-dependent electric potentials on the main electrodes of the ion source or attached or joint ion analytical instrument In some embodiments, the inventive CIN-LDI/CIN-MALDI ion source system may operate at elevated pressures to achieve collisional sample ion cooling. In some cases, the collisional cooling is based on electro-pneumatic superposition. In some embodiments, the system operates with pulsed gas flow fields. In still other embodiments, the system operates with pulsed or arbitrarily time-dependent electric potentials on the main electrodes of the ion source or attached of joint ion analytical instrument In some embodiments of the inventive CIN-LDI/CIN-MALDI ion source system, the CIN-ion source may be a separable and detachable component of the CIN-MALDI ion source. In other embodiments, the CIN-ion source is an integral part of the CIN-MALDI ion source. In some embodiments of the inventive CIN-LDI/CIN-MALDI ion source system, the CIN-LDI/CIN-MALDI may be attached to an ion analytical instrument. In other embodiments, it is attached to a MS (e.g. linear TOF, refectron TOF, quadrupole, ion trap [incl Orbitrap], Fourier transform ion cyclotron resonance MS, etc.), MS-MS (e.g. triple-quad TOF, TOF-TOF, trap-TOF etc.), or any other tandem mass spectrometer or MSn instrument or combination thereof. In still other embodiments, it may be connected to a quadrupole or multi-pole with the CIN-beam being injected into the ion source on the axis of the quadrupole or multi-pole. In still other embodiments, it may be connected to a tetrahedral ion trap (patent to be filed separately) In some embodiments of inventive CIN-LDI/CIN-MALDI ion source system, the CIN-LDI/CIN-MALDI ion source may be a separable device attached an ion analytical instrument. In the other embodiments, it may be an integral part of an ion analytical instrument. In some embodiments of the inventive CIN-LDI/CIN-MALDI ion source system, the CIN-beam and laser beam may be simultaneously scanned over the sample and/or chip. Optimized Control Aspects of the present invention relate to systems and methods for optimizing the control of an ion source utilizing electro-pneumatic superposition connected to a mass spectrometer by feedback from operational data and to optimizing results obtained by a mass spectrometer or other instrumentation receiving ions from the ion source. Aspects of embodiments of the present invention relate to systems and methods that optimize the control of ion sources employing electro-pneumatic superposition, the ion sources being operably connected to a mass spectrometer. Methods and systems of control include collecting and analyzing data from the mass spectrometer during its operation, generating signals from the data analysis, and providing the signals as feedback to control various aspects of the operation of the ion source. Data from which informative feedback signals are generated may include the mass spectrum data from a sample being analyzed, and may also include data from sensors reporting conditions from the locale of the ion source, as well as data from other sources. The ion source of mass spectrometers controlled by embodiments of these systems and methods may include ion sources of the laser desorption ionization type as well as the electrospray type. Some embodiments of the ion source may make use of charge injection (CIN-LDI/CIN-MALDI), and may further make use of two-dimensional sample chips. Objectives of the optimization of the control of the ion source include optimally guiding ions, cooling ions collisionally, and optimally guiding droplets containing sample ions. Optimizing control may be effected by various approaches, for example, by changing the multiplicity of the gas reservoir pressures used to supply gas to the ion source region in which the electro-pneumatic superposition occurs, or by controlling changing the total gas flow to the ion source region in which the electro-pneumatic superposition occurs. Optimizing control may further be effected by changing the electric potentials on electro-pneumatic elements. Optimizing control may further be effected by changing the mechanical arrangement of electro-pneumatic elements such as angles or gap-width by means of active drives such as stepper motors. Optimizing control may still further be effected by changing the timing behavior of the electric or pneumatic parameters. Optimizing control may even still further be effected by changing the operation of a pump connected to the ion source or the gas flow to said pump by means of a throttling valve. Embodiments of the presently described active control system may assume various configurations, for example, they may be integrated into the control system of the ion source, they may be integrated in the control system of the mass spectrometer, or they may be stand-alone devices. Embodiments of the active control system may make use of information obtained throughout the entire mass spectrometric data acquisition process to provide feedback information to optimize the performance of the ion source, or they may make use only of information obtained during an initial phase of the mass spectrometric data acquisition process. In these embodiments, the active control system is providing feedback in real time. Other embodiments of the active control system may make use of stored information, which may also be encoded in the sample itself or on a bio-chip. Embodiments of the active control system may make use of an algorithm that derives variously from any of the control signals provided to the ion source from the total ion count, from the signal to noise ratio in the mass spectrum, and/or from the amount of fragment or cluster ions in the mass spectrum. Radiation Supported Charge-Injection Liquid Spray Aspects of the present invention relate to systems and methods for improving the sensitivity of ion sources based on spraying liquids, and improving their usefulness as a quantitative tool, when connected to a mass spectrometer or other equipment. Described herein are various aspects of embodiments of a “Radiation supported Charge-Injection Liquid Spray” (RCIN-LS) device and associated methods of operation. In broad terms, these embodiments are devices for outputting ions where (1) droplets of a liquid (or liquid crystal) containing sample molecules are generated, (2) one or more low energy charge injection ion beam(s) (CIN-beam) of stable low molecular weight ions (including protons) originating from an ion gun is controlled and directed with specific kinetic energy by electric and/or magnetic fields onto one or more droplets, thereby increasing the net charge of said droplets, and/or (3) having the droplets exposed to a single or a plurality of controlled and directed beam(s) of electromagnetic radiation (such as optical, UV, IR (including laser]; microwave) in order to control its (their) temperature and evaporation rate both influences (2 and 3) combined increasing the total sample ionization efficiency and ionization uniformity (across different molecular species) of the device/ion source. CIN- and EM-beam variations include methods and devices where (1) beams may be deflected, (2) beams may be synchronized, and/or (3) beams may be controlled by video/timing. Variations of the charge-injection aspect of the RCIN-LS ion source and connected devices may include any of the following: 1. The ion gun feeds ions into an ion trap to accumulate CIN-ions which are then pulsed into the ES region. 2. The CIN-beam is pulsed or pulse-like arbitrarily time-dependent modulated, synchronized with the droplet formation and acceleration potentials on the electrodes in the ion source are turned off or floated during the CIN ion injection but turned on thereafter to extract created droplets and/or sample ions with pulsed or arbitrarily time-dependent electric potentials on the main electrodes of the ion source or attached or joint ion analytical instrument with pulsed or arbitrarily time-dependent electric potentials on the main electrodes of the RCIN-LS ion source. 3. The CIN-ion gun is a separable and detachable component of the RCIN-LS ion source, or the CIN-ion gun being an integral part of the RCIN-LS ion source. 4. The RCIN-LS ion source is either (1) a separable device attached an ion analytical instrument or (2) being an integral part of an ion analytical instrument. 5. The ion analytical instrument may be any of various types, including a. Any of various mass spectrometer types, including linear TOF, refectron TOF, quadrupole, ion trap. b. A Fourier transformed ion cyclotron resonance mass spectrometer, or Orbitrap. c. A MS-MS (for example, triple-quad TOF, TOF-TOF, trap-TOF, etc.), or any other tandem mass spectrometer or MSn instrument or combination thereof. 6. The RCIN-LS ion source may be connected to a RF multi-pole with the CIN-beam being injected into the ion source on the axis of multi-pole. 7. The RCIN-LS ion source may be connected to a tetrahedral ion trap (per patent application being filed separately). Variations of the EM-beam aspect of the ion source may include any one or more of the following: 1. may be IR, UV, or visible Laser. 2. may be any of known variants of solid state or gas phase lasers, OPO lasers. 3. semiconductor lasers such as laser-diodes or arrays thereof. 4. may be intense incandescent lamps, arc, glow discharges etc. 5. may be exposure to microwave or Terahertz electromagnetic radiation. 6. may include electronically controlled deflection. 7. may include electronically controlled attenuation. 8. may include electronically controlled synchronization. 9. may hit a single or multiple droplets. Variations of the general RCIN-LS ion source design may include any one or more of the following: 1. The droplet formation/nebulization, droplet guidance, and ion guidance is supported by electro-pneumatic superposition by means of electro-pneumatic elements which create specifically designed electric fields as well as gas flow fields. 2. The liquid containing sample molecules is dispensed utilizing “controlled liquid ejection” by means of a inkjet printer like mechanism, with any of the following variations: a the droplet generation/ejection is synchronized with the charge injection. b a single packet of CIN ions is directed a at a single droplet. c a single packet of CIN ions is directed a at multiple droplet. 3. The design may have an active control system operate the ion source and optimize its performance, the active control system having knowledge/data from previously performed modeling and/or (a) reduced order model(s) based said modeling and using such knowledge/data to perform/optimize the ion source control. 4. The design may have an active control system operate the ion source and optimize its performance, the active control system analyzing mass spectrometric data and such data to derive control signal for the ion source 5. The droplets may be exposed to synchronized and pulsed electric fields of high strength to support ionization.Ion Source with Controlled Liquid Injection Aspects of the present invention relate to means which improve sensitivity of ion sources based on spraying liquids and their usefulness as quantitative tool when operably connected to a mass spectrometer or other device. Aspects and embodiments of the presently described invention relate to apparatus and methods to make the droplet formation largely independent of the pressure and rate with which the liquid is supplied, the degree of dissociation of the sample molecules, the electric conductivity of the liquid, and the electric field at the capillary tip from which the droplets are released. More particularly, embodiments of the invention may include an ion source wherein the liquid containing sample molecules is dispensed from a capillary-like or needle-like hallow structure, or at least a small opening by means of a mechanism (an “Inkjet printer like mechanism”) that enables electrically controlled formation and ejection of droplets of specific size and with specific initial velocity. Embodiments of the inventive apparatus may include ejection heads for dispensing a liquid, which may include any one or more of the following elements and features: 1. a liquid reservoir to which the sample-containing liquid or liquid crystal is fed, 2. the liquid or liquid crystal leaving the reservoir through a small nozzle-like or tube-like opening with a typical diameter smaller than a typical dimension of said reservoir, 3. the liquid and/or gas pressure in the reservoir being controlled by a electrically driven means (such as piezoelectric, electrostatic, electromagnetic, electro-optically) such that single droplets or a plurality of droplets of predominantly of a specific size is formed and ejected with a specific velocity at times determined by the driving electric signal, 4. having a plurality of ejection heads to increase throughput, 5. having a plurality of ejection heads to enable different droplet size, the heads being fed from one or more reservoirs, 6. having an active control system analyze obtained mass spectra and to choose optimal droplet size, initial velocity and/or timing (frequency), 7. having the control/timing of the droplet ejection synchronized with electric fields created by electrodes or electro-pneumatic elements inside the ion source to optimize droplet guidance, nebulization, ionization and ion guidance, 8. the ejection head(s) being simultaneously an electrode(s) and/or electro-pneumatic element(s), 9. having the ejection head(s) controllably generate a single droplet or multiple droplets to be used for executing mass analysis, 10. the ejection head(s) being part of a micro-fluidic chip being inserted in the ion source 11. mixing droplets in flight, 12. axial or radial droplet injection, and 13. injection of droplets in region of very high electric field strength sufficient to cause ion extraction. The mass spectrometer and operational context for the embodiments of the ejection heads may include an instrument that utilizes electro-pneumatic superposition, charge injections, as well as radiation supported charge-injection. The mass spectrometer may further make use of an active computer controlled feedback system that analyzes mass spectra data or data from sensors that report from the vicinity of the ion source to optimize the ion source operation. The ion source, itself, may be either a separable device attached to an ion analytical instrument or an integral part of an ion analytical instrument. The ion analytical instrument may be any of various types, including (a) any of various mass spectrometer types, including linear TOF, refectron TOF, quadrupole, ion trap, (b) a Fourier transformed ion cyclotron resonance mass spectrometer, or Orbitrap, or (c) A MS-MS (for example, triple-quad TOF, TOF-TOF, trap-TOF, etc.), or any other tandem mass spectrometer or MSn instrument or combination thereof. Aspects of the present invention provide methods, apparatus, systems, processes and other inventions relating to: ion sources with controlled electro-pneumatic superposition, ion source synchronized to RF multipole, ion source with charge injection, optimized control in active feedback system, radiation supported charge-injection liquid spray, ion source with controlled liquid injection as well as various embodiments and combinations of respective elements of some and/or each of the foregoing in additional embodiments. Ion Sources with Controlled Electro-Pneumatic Superposition Aspects of apparatus and methods of certain embodiments of the present invention rely upon the controlled superposition of gas flow fields and electrostatic fields within an ion source to effect rapid collisional cooling with improved collection, collimation, and output of ions. The high efficiency injection of unfragmented ions into ion analytical instruments to which the source may be operably coupled can significantly increase the sensitivity of the instrument. In a first aspect, certain embodiments of the invention provide an ion source device. According to aspects of some embodiments of the present invention, in a first region of an ion source, radially-inward axisymmetric gas flow creates ion-guiding gas flow (pneumatic) fields that predominate in their effects on ion motion over electrostatic fields during operation of the device. This collision-dominated first region effects rapid collisional cooling as well as ion capture and trajectory collimation. In the second region of the source, ion-guiding electrostatic fields predominate in their effects on ion motion over gas flow fields created by radially-outward axisymmetric gas flow during use. In this electrostatically-dominated second region, ions are separated from the gas and electrostatically guided toward subsequent ion analytical instruments; the electrostatic fields are such that negligible collisional heating occurs. FIG. 1A is a schematic cross-section of an embodiment of an ion source device according to aspects of the present invention. The cross-section is taken along device axis A-A, defined by ion introduction or generation means 5 on the proximal end and ion outlet 18 on the distal end of ion source 100. In FIG. 1A, ion source 100 is shown operably engaged at its distal end to the proximal end of analytical instrument 200, shown in partial cross-section, and axis A-A is shown extending into first multipole 7 of analytical instrument 200. Ion source 100 may comprise first housing 10 and second housing 12. First housing 10 is sealingly engaged to second housing 12 through interface partition 14, which partition provides, however, for axial communication of gas and ions between first and second housings, as further described below. First housing 10 and second housing 12 can be separately constructed and subsequently fused, with either or both contributing to interface partition 14, or can be of integral construction. First housing 10 may comprise at least one pneumatic element 6 that segregates the space within first housing 10 into gas reservoir 4 and ion expansion chamber 8. In typical embodiments, first housing 10 may comprise a plurality of pneumatic elements 6, the plurality of pneumatic elements segregating the space within the first housing into gas reservoir 4 and ion expansion chamber 8. The one or more pneumatic elements 6 are so shaped and so disposed within housing 10 as to cause gas reservoir 4 to be in axisymmetric gas communication with ion expansion chamber 8. First housing 10 further may comprise at least one, typically a plurality of, gas inlets 3 that communicate gas reservoir 4 with the exterior of first housing 10. Gas inlets 3 are preferably positioned symmetrically in housing 10; in embodiments in which housing 10 is cylindrical, gas inlets 3 can usefully be axisymmetrically arranged in housing 10. Symmetrical disposition of gas inlets 3 provides maximum isotropy of gas pressure in gas reservoir 4. Gas inlets 3 are typically also designed to minimize turbulence at the point of gas entry into gas reservoir 4: in some embodiments, for example, gas inlets 3 are baffled. Gas present in gas reservoir 4 during use of the ion source is schematized by stippling in FIG. 1A. Second housing 12 may comprise at least one pneumatic element 20 that segregates the space within the second housing into axial trajectory region 22 and gas sink region 24. In typical embodiments, second housing 12 may comprise a plurality of pneumatic elements 20, the plurality of pneumatic elements segregating the space within the first housing into axial trajectory region 22 and gas sink region 24. The one or more pneumatic elements 20 are so shaped and so disposed within second housing 12 as to cause axial trajectory region 22 to be in axisymmetric gas communication with gas sink region 24. Second housing 12 further may comprise at least one, typically a plurality of, gas outlets 26 that communicate gas sink region 24 with the exterior of second housing 12. Gas outlets 26 are preferably positioned symmetrically in second housing 12; in embodiments in which housing 12 is cylindrical, gas outlets 26 can usefully be axisymmetrically arranged in housing 12. Symmetrical disposition of gas outlets 26 provides maximum symmetry in radially outward gas flow fields during use. In various embodiments (not shown in FIG. 1A), the second housing may further comprise additional gas flow guiding means (pneumatic elements) which help maintain axisymmetrically outwardly directed gas flow out of the gas sink region, although at some point during the spatial transition from the gas sink region to the exterior of the second housing, spatial symmetry may be broken. With continued reference to FIG. 1A, expansion chamber 8 is axially aligned with and in gas and ion communication with axial trajectory region 22. Axial trajectory region 22 is in axial alignment with and in ion communication (and optionally also in gas communication) with ion outlet 18 of device 100. In the embodiment shown in FIG. 1A, axial trajectory region 22 and ion outlet 18 are in axial alignment with multipole 7 of ion analytical instrument 200, with partition 16 and distal-most pneumatic elements 20 forming a sealing engagement with ion analytical instrument 200. In order to establish electrostatic fields capable of acting upon ions introduced into expansion chamber 8, housing 10 optionally, but typically, may comprise at least one electrically conductive element. In the embodiment shown in FIG. 1A, for example, element 28 can be an electrically conductive element. Typically, at least a portion of at least one of the pneumatic elements 6 in housing 10 is electrically conductive; the electropneumatic element contributes to both gas flow (i.e., pneumatic) fields and electrostatic fields during use. In the schematized embodiment shown in FIG. 1A, electrically conductive element 28 can also be such an electropneumatic element 6. In various embodiments, at least a portion of a plurality of pneumatic elements 6 in housing 10 is electrically conductive, the plurality of electropneumatic elements contributing to both pneumatic fields and electrostatic fields during use. In the schematized embodiment shown in FIG. 1A, electrically conductive element 28 can be one of the plurality of such electropneumatic elements 6. In certain embodiments, all of a plurality of pneumatic elements 6 in housing 10 are electrically conductive, the plurality of electropneumatic elements contributing to both pneumatic fields and electrostatic fields during use. In the schematized embodiment shown in FIG. 1A, electrically conductive element 28 can be one of the plurality of such electropneumatic elements 6. Analogously, in order to establish electric, typically electrostatic, fields capable of acting upon ions introduced into axial trajectory region 22, and optionally capable of acting upon ions within expansion chamber 8, housing 12 further may comprise at least one electrically conductive element. Typically, at least a portion of at least one of pneumatic elements 20 in housing 12 is electrically conductive; the electropneumatic element contributes to both gas flow (i.e., pneumatic) fields and electrostatic fields during use. In various embodiments, at least a portion of a plurality of pneumatic elements 20 in housing 12 is electrically conductive, the plurality of electropneumatic elements contributing to both pneumatic fields and electrostatic fields during use. In certain embodiments, all of a plurality of pneumatic elements 20 in housing 12 is electrically conductive, the plurality of electropneumatic elements contributing to both pneumatic fields and electrostatic fields during use. In certain embodiments, the potentials applied to the electrically conductive elements of ion source 100 can usefully be ramped coordinately with AC potential stepping of an RF multipole of an ion analytical instrument to which the source is operably coupled, as further described and claimed in the commonly owned patent application entitled “Methods And Apparatus For Controlling Ion Current In An Ion Transmission Device”, the disclosure of which is incorporated herein by reference in its entirety. FIG. 1B. schematizes exemplary gas flow and ion trajectories during operation of the ion source device of FIG. 1A, with exemplary gas flows shown in solid arrows and exemplary ion trajectories shown in dashed arrows. Gas, from either a dedicated reservoir (not shown) or directly or indirectly from atmosphere, is routed through gas line 1 to gas inlets 3 of first housing 10 by maintaining gas sink region 24 within second housing 12 at lower pressure than gas reservoir 4, as for example by outward pumping at gas outlet 26 of second housing 12. The gas can usefully be selected, for example, from the group consisting of atmospheric gas, conditioned atmospheric gas, nitrogen, and noble gases, such as argon. Conditioning of atmospheric gas can include, e.g., removal of moisture using a moisture trap and/or removal of particulates using one or more filters of various porosity. Usefully, gas line 1 includes one or more flow adjustment means 2, such as one or more throttling valves, disposed between the gas source and gas inlets 3 of housing 10, permitting the resistance to inward gas flow to be adjusted. Optionally, flow adjustment means 2 may be actively controlled by an electronic feedback system which measures the gas pressure in gas reservoir 4 at one or more points and adjusts the gas flow through line 1 such that the pressure in reservoir 4 is maintained with high accuracy at a constant value, even if operating conditions and or pumping power might fluctuate. Gas reservoir 4 is maintained at a pressure that is typically subatmospheric, but greater than that in gas sink region 24. As a result, gas flows radially inward between pneumatic (optionally, electropneumatic) elements 6 into expansion chamber 8. For the most part, the gas pressure inside gas reservoir 4 is spatially constant. On average only negligible gas flow speeds occur inside the gas reservoir as compared to gas flow speeds in the expansion chamber, as shown in the gas flow velocity magnitude contour plot of FIG. 5, further described herein below. In some embodiments, the gas inlets comprise means to baffle inward streaming gas flow to facilitate the achievement of such pressure and flow characteristics. The radially inward axisymmetric flow of gas from gas reservoir 4 into expansion chamber 8 is further illustrated in FIG. 4B, which presents a perspective view of an axial cross-section of device 100 with a portion of first housing 10 and second housing 12 schematized; stippled arrows schematize the radially inward axisymmetric gas flow from the gas flow reservoir toward the expansion chamber within first housing 10. With reference to FIG. 1B, ion trajectories in expansion chamber 8, exemplified by dashed arrows, are shaped principally by the above-described gas flow fields, which predominate in their effects on ion motion over any electrostatic fields that may also be extant in housing 10 during use. Gas then flows from expansion chamber 8 into axial trajectory region 22, radially outward axisymmetrically through pneumatic (optionally, electropneumatic) elements 20, through gas sink region 24, and thence through at least one, typically through a plurality of, symmetrically disposed gas outlets 26. In typical embodiments, the collective gas flow resistance of second housing gas outlets 26 is lower than the collective gas flow resistance of first housing gas inlets 3. In a typical embodiment, the difference in gas flow resistance is accomplished by using outlets having greater collective cross sectional area than the collective cross sectional area of the gas inlets. In various embodiments, the gas flow through either or both of gas inlet(s) 3 and gas outlet(s) 26 are adjustable during device use. Although not shown in FIGS. 1A and 1B, gas flow outlets 26 of second housing 12 may, in certain embodiments, be in gas flow communication with means, disposed outside housing 12, for adjusting outward gas flow. Such means include, for example, one or more variable or constant flow resistors, throttling valves, or controllable pumps disposed outside housing 12; the flow adjustment means can be used to set the minimum pressure inside gas sink region 24 and/or to influence the gas flow vector field within housing 12. Furthermore, in various embodiments such as that schematized in FIG. 1C, second housing 12 may comprise additional pneumatic elements 21 that help maintain axisymmetrically outwardly directed gas flow out of gas sink region 24, notwithstanding a break in symmetry from the gas sink region to the exterior of the second housing. For example, in the embodiment of FIG. 1C, a single gas outlet 26 is disposed asymmetrically in second housing 12; notwithstanding the lack of symmetry in gas flow outwards through second housing 12, additional pneumatic elements 21 so baffle outward air flow as to maintain axisymmetric gas flow through most of gas sink region 24. As exemplified in FIG. 1B, ion trajectories in axial trajectory region 22 are little affected by the radially outward axisymmetric gas flow fields in second housing 12. The radially outward axisymmetric gas flow vectors have little defocusing effect on the ion trajectories in this region because the spatially varying gas pressures are significantly lower than the pressure in expansion chamber 8, and because ion trajectories are dominated in axial trajectory region 22 by electrostatic forces. FIG. 2 is a schematic axial cross-section of another embodiment of an ion source device according to the present invention, operably engaged to the initial portion of a multipole-containing ion analytical instrument. In the embodiment of FIG. 2, element 28 extends proximally into contiguity with housing 10. Gas inlets 3 are, as in the embodiment shown in FIGS. 1A and 1B, symmetrically disposed, maintaining maximum isotropy of gas pressure in gas reservoir 4. As in the embodiment of FIGS. 1A and 1B, pneumatic (optionally, electropneumatic) elements 6 are so shaped and so disposed as to effect radially inward, axisymmetric gas flow from gas reservoir 4 into expansion chamber 8 during use. FIG. 3 is a schematic axial cross-section of a further embodiment of an ion source device according to the present invention. In this embodiment, the ion source is coupled to an ion analytical instrument in a geometry that permits gas additionally to be evacuated through gas outlets 26 from the ion analytical instrument's multipole region. FIGS. 4A-4C are perspective views of an axial section through embodiments of an ion source according to the present invention. Element 28 (optionally electrically conductive, optionally an electropneumatic element), pneumatic (optionally, electropneumatic) elements 6, and pneumatic (optionally, electropneumatic) elements 20 of ion source device 100 are shown operationally aligned with multipole 7 of ion analytical instrument 200. In FIGS. 4A and 4C, housings 10 and 12 are omitted; in FIG. 4B, a portion of each of housings 10 and 12 is schematized. As in FIGS. 1A and 1B, FIGS. 4A-4C show a single element 28, which can optionally be an electrically conductive element 28 or an electropneumatic element 6; two pneumatic (optionally, electropneumatic) elements 6; and two pneumatic (optionally, electropneumatic) elements 20. The number of electrically conductive and pneumatic elements is not critical to the invention, however, and there may be fewer or greater numbers of electrically conductive and pneumatic (optionally, electropneumatic) elements in various embodiments. In the embodiments of FIGS. 4A-4C and FIGS. 5-9, the pneumatic elements (optionally, electropneumatic elements) 6 are so shaped and so disposed that the point of greatest constriction to radially inward axisymmetric gas flow—between element 28 and proximal pneumatic element 6, and also between the proximal and distal pneumatic elements 6—is in immediate proximity to ion expansion chamber 8. In some embodiments the point of greatest constriction is in a facilitating general proximity to the ion expansion chamber. The flow resistance beyond these points of greatest constriction—i.e., within ion expansion chamber 8, axial trajectory region 22, gas sink region 24, and gas outlets 26—is much lower than the flow resistance at the points of closest constriction. As a result, high gas expansion velocities occur radially inward into expansion chamber 8, as further shown in the simulations shown in FIGS. 5 and 6. In some embodiments, the magnitude of the velocity vectors just after the point of greatest constriction may be generally from 100 to 300 m/sec although lower or higher magnitudes may also be used. In some other embodiments, the magnitude of the velocity vectors just after the point of greatest constriction may be from 250 to 300 m/sec. In these embodiments, this high speed gas flow impacts the ion plume. The simulation depicted in FIGS. 5 and 6 (as well as in the others of FIGS. 4C-10) were performed using methods such as those described in the following references, incorporated herein by reference in their entireties: Andreas Hieke, “GEMIOS—a 64-Bit multi-physics Gas and Electromagnetic Ion Optical Simulator”, Proceedings of the 51st Conference on Mass Spectrometry and Allied Topics (Jun. 8-12, 2003, Montreal, PQ, Canada); Andreas Hieke “Theoretical and Implementational Aspects of an Advanced 3D Gas and Electromagnetic Ion Optical Simulator Interfacing with ANSYS Multiphysics”, Proceedings of the International Congress on FEM Technology, pp. 1.6.13 (Nov. 12-14, 2003, Potsdam, Germany); Andreas Hieke, “Development of an Advanced Simulation System for the Analysis of Particle Dynamics in LASER based Protein Ion Sources”, Proceedings of the 2004 NSTI Nanotechnology Conference and Trade Show Nanotech 2004 (Mar. 7-11, 2004, Boston, Mass., U.S.A.). FIG. 5 is an axial section of a mathematically modeled contour plot of gas flow velocity magnitudes during use of an embodiment of an ion source device according to the present invention that is similar to the embodiments schematized in FIGS. 4A-4C; darker regions indicate higher velocity gas flow. FIG. 6 is an axial section of a mathematically modeled vector plot of gas flow velocity during use of an embodiment of an ion source device similar to the embodiments schematized in FIGS. 4A-4C. The pressure in gas reservoir 4 is chosen such that, for a given resistance to radially inward, axisymmetric gas flow, the pressure and velocity distribution in expansion chamber 8 pneumatically collects and cools effectively all of the ions ejected from the ion introduction or generation means, such as ions present in plume ejected from a laser desorption ionization probe. FIG. 7 shows a mathematically modeled contour plot of the distribution of gas pressures during use of an embodiment of an ion source device according to the present invention similar to the embodiments schematized in FIGS. 4A-4C; higher pressures are in darker shades. As can be seen, the pressure throughout gas reservoir 4 is essentially constant, with a dramatic drop in pressure occurring upon entry to expansion chamber 8. As can also be seen, pressures within ion source 100 are effectively decoupled from that in RF multipole 7 of ion analytical instrument 200. There is a variety of pressure differentials that can be utilized in various embodiments between gas reservoir 4 and the expansion chamber 8. In some embodiments the pressure in the gas reservoir 4 may be as little as only twice the dominant pressure in the expansion chamber 8 to which the ions are exposed. In other embodiments, the pressure in the gas reservoir 4 may be 5, 10, 20, or 50 or more times the dominant pressure in the expansion chamber 8. In one prototype embodiment the pressure in the gas reservoir 4 was about 10 times the dominant pressure in the expansion chamber 8. In that prototype embodiment the pressure in the gas reservoir was adjusted, with the embodiment operating successfully, to be from about 25 to 400 Pa and operated more successfully at between 100 and 300 Pa. FIG. 8 shows a contour plot of the mathematical product of the modeled gas flow velocity magnitude and gas pressures—providing a measure of collisional effects—in an embodiment of an ion source device according to the present invention similar to the embodiments shown in FIGS. 4A-4C. The contour plot demonstrates the predominance of collisional effects in the pneumatically dominant first phase of ion guidance, confirming that rapid collisional cooling is effected in ion source devices according to the present invention. A rapid cooling of the ions is accomplished. In some embodiments the ions are cooled to approximately the gas temperature in the order of 10−5 seconds or less from the point in time at which the ions are ejected from the sample by effect of the laser pulse. In other embodiments, the ions are cooled to approximately the gas temperature in less than 10−4 seconds from the point in time at which the ions are ejected from the sample by effect of the laser pulse. Additionally, in other embodiments the ions can be cooled in one microsecond or less. In certain embodiments, the gas temperature in the expansion region 8 is in a range of from 250 to 300 K, although higher and lower temperatures can be used. The often significant temperature drop of the gas passing through the constrictions results in highly cooled gas which supports the collisional cooling of the sample ions. FIG. 9 shows a mathematically-modeled vector plot of the electrostatic fields during operation of an embodiment of an ion source device of the present invention that is similar to the embodiments shown in FIGS. 4A-4C, at one set of electrical potentials. FIG. 10 shows modeled ion trajectories for one set of operating conditions of an embodiment of an ion source device according to the present invention, the embodiment being similar to the embodiments shown in FIGS. 4A-4C, demonstrating electropneumatic capture and axial guidance of ions ejected from the ion introduction or generation means, including ions ejected in an off-axis direction. FIG. 4C shows modeled ion trajectories in perspective view. As described herein, the extent of ion cooling that occurs in an ion source device of the present invention may be controlled by the gas pressure in the gas reservoir, the configuration of the pneumatic and/or electropneumatic elements in the device, etc. Accordingly, operating the device at an elevated pressures, such that the gas pressures and/or velocities in the ion expansion chamber are correspondingly increased, may result in more rapid collisional cooling of ions introduced in this chamber. However, one effect that may result from this increased pressure is clustering between ions and matrix material in the device. Such clustering may be undesirable, as the apparent mass and/or charges of the ions may be affected, thereby resulting in problems in subsequent analysis of these ions. To counter this clustering, the ions may be subjected to a moderate amount of collisional heating in a controlled fashion. This heating may be effected by increasing the ion velocities in either or both the first and the second housings, the heating resulting from increasing the collision rate between the ions and the gases therein. The ion velocities may be increased by increasing the electric field magnitudes within either or both the first and the second housings in various embodiments of the present invention. For example, by applying appropriate potentials to one or more of the electrostatic and/or electropneumatic elements in the device, the ion velocities are increased, thereby resulting in a moderate amount of collision heating. The appropriate amount of collisional heating may be determined empirically, for example, by increasing the collision heating when the device is being operated at an elevated pressure until the extent of ion/matrix clustering has been reduced to an acceptable level. As described above, the advantages of an ion source device of the present invention result from, inter alia, controlled superposition of the electrostatic fields and pneumatic fields within the device. The extent of superposition of these two fields is a result of factors such as the physical configuration of the device (e.g., the pneumatic, electrostatic, and electropneumatic elements) and the operating parameters of the device, such as the gas pressures and velocities, and the potentials applied to one or more of the conductive elements. Referring to FIGS. 12A and 12B, experimental results using an ion source embodiment of the present invention is depicted. In these examples, the ion source is used to generate ions from about 10 fmol of a peptide (amino acid residues 661-681 of epithelial growth factor receptor) using a MALDI probe. For each experiment, the ion count for each detected ion was determined (I) and plotted as its ratio of the maximum ion count (Imax). FIG. 12A depicts the results of the experiment when performed at a gas pressure of 25 Pa, whereas FIG. 12B depicts the results at a gas pressure of 200 Pa. At the higher pressure, the same ion device produced not only a higher overall ion transmission as indicated by the Imax, but also a lower amount of fragmentation of the expected ion peak. In contrast, the experiment at the lower pressure resulted in a lower ion transmission and a higher degree of ion fragmentation. Therefore, although collisional cooling occurred in both examples, the superposition of the electrostatic and pneumatic gas fields in the experiment of FIG. 12B was more effective, thus resulting in both improved ion transmission and a lower degree of ion fragmentation. Referring to FIG. 13, the pressure dependence on superposition is shown. Here, a prophetic experiment in which the maximal ion count (Imax) is shown to be dependent on the operating pressure in a given embodiment of the present invention. Accordingly, it is desirable to determine the optimum operating pressure when using a given ion device. This optimum pressure may be determined either experimentally, empirically, theoretically, or some combination thereof. Referring to FIGS. 14A and 14B, the importance of the superposition during use of an ion source of the present invention is further demonstrated. In these examples, each ion source is used to generate ions from about 10 fmol of a peptide (phosphorylated protein kinase C substrate having the amino acid sequence TSTEPQYQPGENL with an expected mass of 1423 Daltons) using a MALDI probe. For each experiment, the ion count for each detected ion was determined (I) and plotted as its ratio of the maximum ion count (Imax). In FIG. 14A, the experiment is performed using a prior art MALDI ion source. As is evident from these results, extensive ion fragmentation due to insufficient cooling is apparent. The expected peak of about 1423 mass unit is not even visible as the predominant peak. In contrast, FIG. 14B depicts the experiment performed using an ion source of the present invention having improved collisional cooling. Here, both the expected mass peak is clearly visible and relatively ion fragmentation has occurred compared to the prior art MALDI source. As described above, each of the various embodiments of an ion source device according to the present invention may comprise ion introduction or generation means, first ion guidance means, and second ion guidance means. The ion introduction or generation means can, for example, be laser desorption ionization means. In laser desorption ionization embodiments, ion introduction or generation means 5 can comprise laser desorption ionization probe engagement means, the engagement means being capable of positioning a laser desorption ionization probe so as to display at least one surface thereof to expansion chamber 8. Probe engagement means 5 can, in some embodiments, be in physical and electrical contiguity with an electrically conductive element 28, as suggested by the schematic shown in FIGS. 1-3: in use, electrically conductive element 28, probe engagement means 5, and the laser desorption ionization probe engaged therein can be commonly set to an electrical potential that contributes to an electrostatic field capable of acting upon ions introduced into expansion chamber 8 from the engaged probe. In certain laser desorption ionization embodiments of the ion source device of the present invention, the laser is usefully directed to the surface of a laser desorption ionization probe by reflection from a mirrored surface of a pneumatic (optionally, electropneumatic) element 20, as schematized in FIG. 11. A steep incidence angle usefully directs the laser substantially along the device axis, perpendicular to the laser desorption ionization probe, creating highly symmetric initial ion velocities. In such embodiments, video observation of the laser focal spot and origin of the ions can be achieved using a similar light path, including reflection from a mirrored surface of a pneumatic (optionally, electropneumatic) element 20. In some embodiments of the present invention, the device may include at least two mirrors, wherein the first mirror is used to reflect the incident desorption ionization laser to the probe surface. The second, separate mirror may then be used for video or other optical observation of the laser focal spot on the probe. As described above, the first ion guidance means are configured to establish ion-guiding pneumatic fields, and optionally electrostatic fields, the ion-guiding pneumatic fields predominating in their effects on ion motion over electrostatic fields during use. The second ion guidance means are configured to establish ion-guiding electrostatic fields and pneumatic fields, the ion-guiding electrostatic fields predominating over pneumatic fields during use. The pneumatic fields of the first ion guidance means and the second ion guidance means are generated, respectively, by radially inward axisymmetric gas flows and radially outward axisymmetric gas flows. In the embodiment schematically illustrated in FIG. 4B, the radially inward and radially outward axisymmetric gas flows are continuous around the device axis. In other embodiments of an ion source device according to the present invention, however, the axisymmetric gas flows can be periodic, rather than continuous, with gas flowing through a plurality of channels disposed between element 28 and pneumatic (optionally electropneumatic) elements 6, between adjacent pneumatic (optionally electropneumatic elements) 6, and between pneumatic elements 20, the plurality of channels arranged with radial symmetry. Such embodiments (not shown) usefully reduce the volume of gas flow required to effect ion collection, collisional cooling, and trajectory collimation, thus reducing pumping needs. FIGS. 1A-1C, 2 and 3 show various embodiments of an ion source device according to the present invention as optionally coupled to the proximal end of an ion analytical instrument. In the ion source device embodiments schematized in FIGS. 1A, 1B, 1C and 2, the ion source device is operably coupled to analytical instrument 200 through sealing engagement via partition 16, which partition provides, however, for axial communication of ions between axial trajectory region 22 of ion source device 100 and the proximal region of analytical instrument 200 through ion source ion outlet 18. In the alternative ion source device embodiment schematized in FIG. 3, ion source device 100 is operably coupled to analytical instrument 200 so as effectively to integrate ion source device 100 into ion analytical instrument 200. In such embodiments, partition 16 is omitted and housing 12 of ion source 100 is made contiguous with a housing of ion analytical instrument 200. Thus, ion source devices of the present invention can be discrete devices, optionally to be coupled to a subsequent ion analytical instrument, or in alternative embodiments can be integrated with an ion analytical instruments. Thus, in another aspect, the present invention provides analytical apparatus comprising an ion source device of the present invention operably coupled to an ion analytical instrument. In some embodiments, the analytical instrument may comprise at least one multipole, typically an RF multipole, often a quadrupole, hexapole, or octapole, positioned proximal to the ion outlet of the ion source device. In a variety of these latter embodiments, the ion source device can be coupled to the analytical instrument so as to effect little or no gas input into or output from such a proximally disposed multipole, as schematized in the embodiments of FIGS. 1A, 1B, 1C and 2; in others of the multipole-containing embodiments, the ion source device may instead be coupled to the analytical instrument so as to additionally encourage gas withdrawal from such a proximally disposed multipole, as schematized in the exemplary embodiment of FIG. 3. The ion analytical instrument of the analytical apparatus can, in some embodiments, comprise at least one mass analyzer, and can comprise a plurality of mass analyzers. The analytical apparatus can, for example, comprise a mass spectrometer, including both single stage and multi-stage mass spectrometers, single quadrupole, single hexapole, multiple quadrupole (q2, q3), multiple hexapole, quadrupole ion trap, linear ion trap, ion trap-TOF, and quadrupole-TOF mass spectrometers, orthogonal quadrupole-quadrupole-TOF (Qq-TOF) including orthogonal quadrupole-quadrupole-TOF (Qq-TOF) with linear quadrupole ion trap, orthogonal hexapole-hexapole-TOF including orthogonal hexapole-hexapole-TOF with linear hexapole ion trap mass spectrometers as well as FTIR and Ion Trap-FTIR mass spectrometers. In a further aspect, the invention provides methods for increasing the collimated output of unfragmented ions from an ion source device, thus increasing the sensitivity of an ion analytical instrument that may optionally be operably coupled to the ion outlet of the ion source. The method may comprise guiding ions introduced into or generated within the ion source device along the device axis to an ion outlet using superposed electrostatic and axisymmetric pneumatic fields, the ion-guiding pneumatic fields predominating in their effects on ion motion over electrostatic fields in a first portion of the ion trajectory, and ion-guiding electrostatic fields predominating in their effects on ion motion over pneumatic fields in a second portion of the ion trajectory. In typical embodiments, the pneumatic fields are generated by establishing radially-inward axisymmetric and radially-outward axisymmetric gas flows in axial succession. Usefully, the methods are practiced using an ion source device of the present invention as above-described. Using the ion source device of the present invention, the magnitude of the gas flows may be controlled, at least in part, by controlling gas flows into the gas reservoir, as for example by throttling the inward gas flow. In other embodiments, the magnitude of the gas flows may be controlled, at least in part, by controlling gas flows out of the gas sink region, as for example by throttling the outward gas flow and/or by controlling outwardly directed pumping of gas from the gas sink region. The magnitude of the gas flows may be controlled, at least in part, by controlling both the gas flows into the gas reservoir and gas flow out of the gas sink region. In some embodiments of methods of the present invention, the electrostatic fields may be generated by applying an electrical potential to each of a plurality of electrically conductive elements in the ion source device. In some embodiments, the potential applied to at least one of the plurality of electrically conductive elements may change between the time of ion introduction into or generation within the ion source device and ion output from the source. In some of these embodiments, the potential applied to a plurality of electrically conductive elements may change during this period. The change in electrical potential can facilitate injection of ions into an RF multipole of an analytical instrument coupled to the ion source device, as further described in commonly owned U.S. patent application Ser. No. 11/063,801 entitled “Methods And Apparatus For Controlling Ion Current In An Ion Transmission Device,” the disclosure of which is incorporated herein by reference in its entirety. In a variety of such embodiments, the potential applied to at least one of the plurality of the electrically conductive elements may be ramped coordinately with AC potential stepping of an RF multipole of an ion analytical instrument to which the ion source device is operably coupled. The methods of the present invention may comprise a subsequent step of performing at least one analysis on at least one species of ion output from the ion source device. For example, the analysis can comprise determining the mass to charge (m/z) ratio of at least one species of ion output from the ion source. If the ion analytical instrument comprises means for performing a plurality of such measurements, either tandem-in-space or tandem-in-time, the methods can usefully comprise the subsequent steps, after guiding ions to the ion source device outlet, of selecting at least one ion species output from the ion source device, often based upon its m/z, fragmenting the at least one selected ion species, and performing at least one analysis on at least one product ion resulting from the fragmented parent ion. In some embodiments, the at least one analysis may comprise a determination of the mass to charge ratio of the product ion. Usefully, the at least one analysis may comprise a product ion scan. The methods of the present invention comprise a step before the step of guiding ions, of introducing ions into, or generating ions within, the ion source device. Any means of introducing ions into, or generating ions within, the source can be used, such as laser desorption ionization. In various embodiments, ions may be generated within the source by laser desorption ionization of a sample disposed on at least one surface of a laser desorption ionization probe. The analytical sample can usefully comprise proteins, the ions being generated from one or more proteins in the sample. In some of these embodiments, the method can further comprise the step, before generating ions, of capturing proteins from inhomogeneous admixture onto a surface of a laser desorption ionization probe, such as a surface enhanced laser desorption probe, such as a ProteinChip® Array available commercially from Ciphergen Biosystems, Inc. (Fremont, Calif., USA). In some embodiments the electro-pneumatic superposition methods and apparatus may be applied to electrospray ion sources, and ion sources as described below controlled liquid injection. In some embodiments there may be provided a plurality of at least partially electrically conductive elements which simultaneously shape and influence electric fields and gas flow fields. Such elements are termed electro-pneumatic elements In some embodiments of ion sources according to the present invention the electro-pneumatic elements are not exclusively made of electrically conductive material but from a combination of both electrically conductive (such as metals) and electrically non-conductive (such as ceramics), or at least a combination of elements with varying electric conductivity such as different metal, alloys, semiconductors or carbon enabling at least partially separation of the portion of the electro-pneumatic element which controls the electric field generation and the portion of the electro-pneumatic element which controls the pneumatic field generation. In some embodiments a plurality of axisymmetric electro-pneumatic elements may be used which form a stack and which is held in position by a plurality of rods on or close to the circumference of the electro-pneumatic elements such that the position as well as the distance between the electro-pneumatic elements on the rods is determined (and can be changed) by a plurality of spacers, small tubes, or similar which too are being held in place be said rods, and: 1. the entire stack is compressed by a plurality of springs, and 2. the complete stack can be removed/replaced from the ion source as a single component, and 3. the electro-pneumatic elements are generally electrically isolated from said rods by isolating rings or spacers inside the hole through which said rod run, and 4. individual rods can also serve to provide electric potential to individual electro-pneumatic elements which are not electrically isolated from certain rods Some embodiments of ion sources according to the present invention may contain a stack of axisymmetric electro-pneumatic elements wherein the gaps between them can be adjusted by stepper motors, or other electromagnetic or piezo-electric drives which can be driven during operation of the ion source by outside control circuitry. In some embodiments axisymmetric electro-pneumatic elements may contain mechanisms which allow adjustments of the inner diameter (aperture) of the elements can be adjusted be (such as in a camera lens). This aperture adjustment may also be effected by stepper motors, or other electromagnetic or piezo-electric drives. In some embodiments the gaps between a plurality of electro-pneumatic elements may be replaced by a large number of circumferentially displaced apertures. In some embodiments of the present invention a plurality of electro-pneumatic elements may be made from a single block of a electrically nonconductive material by milling, etching or other means and electrically conductive components are added after this process by ways of partially coating (such as metal films), or filling cavities or gaps in the electrically nonconductive material with electrically conductive material. Such method/configuration enable inexpensive mass fabrication of stacks of electro-pneumatic elements. In some embodiments of the present invention a number of electro-pneumatic elements to generate electric and pneumatic fields and to guide ions wherein separate housings (chambers, spaces) may be used, but no clear distinction regarding dominating electric or dominating pneumatic forces can be made. In some embodiments of the present invention a number of electro-pneumatic elements to generate electric and pneumatic fields and to guide ions may be used, but no clear distinction between separate housings (chambers, spaces) can be made. In some embodiments of the present invention the electro-pneumatic elements may be shaped such that coaxially inwardly directed jets are created which supportion guidance. The creation of the jet is accomplished by having the strongest constriction (gaps) of the gas flow in the immediate vicinity of the location where high gas flow velocities are desired. In some embodiments of the present invention the significant gas temperature drop inside said high speed gas jets (which can reach supersonic velocities) may be used to effect and support very rapid collisional ion cooling and/or collisional ion cooling down to temperatures lower than the temperature of the supplied collisional cooling gas at rest. Ion Source Synchronized to RF Multipole In apparatus and methods of the present invention, an ion source is in ion communication with an ion transmission device. Applying a set of operating parameters to the ion source can determine the characteristics of the ions generated by the ion source. Similarly, applying a set of operating parameters to the ion transmission device can determine the characteristics of the ions transmitted through the ion transmission device. Applying a set of operating parameters to the foregoing components refers to setting or providing values for one or more of their operating parameters. In a first aspect, the present invention provides methods for controlling the ion current of an ion transmission device in ion communication with an ion source. The method may comprise coordinating the operating parameters of an ion transmission device with the operating parameters of an ion source. In some embodiments, the method may involve coordinating values of the operating parameters of the respective components. Examples of operating parameters of the ion transmission guide source include, without limitation, any characteristics of the potentials applied to one or more of the electrodes of the ion transmission guide, such as the electrodes of a multipole radio-frequency ion guide. Such characteristics include, without limitation and where relevant, the characteristics of applied DC potentials, AC potentials, or any other arbitrarily time-dependent waveform. These include the magnitude of the applied potentials, wherein the magnitude may be determined by absolute value, peak, root-mean-square, average, or the like. These characteristics also include the frequencies and amplitudes of applied waveforms, the magnitudes of phase shifts between two or more applied waveforms, the shapes of applied waveforms, pertinent time intervals between changes in state and other values, and other like characteristics. Examples of operating parameters of the ion source that can be coordinated with operating parameters of the ion transmission guide include, without limitation, any characteristics of the potentials applied to one or more of the electrodes of the ion source. Such characteristics include, without limitation and where relevant, the characteristics of applied DC potentials, AC potentials, or any other arbitrarily time-dependent waveform. These include the magnitude of the applied potentials, wherein the magnitude may be determined by absolute value, peak, root-mean-square, average, or the like. These characteristics also include the frequencies and amplitudes of applied waveforms, the magnitudes of phase shifts between two or more applied waveforms, the shapes of applied waveforms, pertinent time intervals between changes in state and other values, and other like characteristics. In some embodiments of the present invention, the operating parameters of the ion source and the ion transmission device may be coordinated such that the characteristics of the ions generated by the ion source are substantially commensurate with the characteristics of the ions transmitted through the ion transmission device. Proper coordination results in improvement of the ion current of the ion transmission device. Coordination of these respective operating parameters may also result in improvements in the measurement and detection of the ions. In some preferred embodiments, a controller may be configured to coordinate the operating parameters of the ion source and the ion transmission device of the present invention. A controller can thereby coordinate the respective operating parameters of the ion source and the ion transmission device in a manner directed towards control of the ion current of the ion transmission device. In some embodiments of the present invention, coordination of the respective operating parameters of the ion source and the ion transmission device may require applying or changing values of one or more of the operating parameters. In some embodiments, these changes or applications of operating parameter values to a first component, such as an ion source, may be effected with regard to changes or applications of values to the operating parameters to a second component, such as an ion transmission device. Such values may include characteristics of the electrostatic or electromagnetic properties of electrodes in the components of interest. Such characteristics may include, for example, the properties of the applied AC or DC potentials, the properties of the applied AC or DC currents, the frequencies and amplitudes of applied waveforms, the magnitudes of phase shifts between two or more waveforms, the shapes of applied waveforms, pertinent time intervals between changes in state and other values, and other like characteristics known to affect the operation of ion sources and ion transmission devices of the present invention. In some embodiments of the present invention, the operating parameters may include either or both of digital and analog values. The operating parameters may include settings for the ion source or ion transmission device that represent or reflect its electric and electronic characteristics, its spatial and physical characteristics, its temporal characteristics, and other characteristics that are known in the art relating to such components. In some embodiments of the present invention, coordination of the values of these respective operating parameters may involve measuring, calculating, querying, recalling, or other suitable method for determining the values of one or more of the operating parameters on a first component (e.g., ion source, ion transmission device, etc.). Such determination may be made transiently or in real-time. For example, the controller may measure directly values of one or more operating parameters of a component (e.g., applied AC or DC potentials, the AC peak amplitude and frequency, etc.). The controller may also calculate or derive one or more operating parameter values based on other known or measured parameters. The controller may query another controller in closer proximity to the component of interest to obtain the desired values. The controller may also recall the values of the operating parameters that were applied previously to the component, instead of determining anew the values from the component itself. It is also understood that suitable combinations of the foregoing determination methods may also be used. Concurrent with or following this determination of the operating parameters, suitable operating parameter values may be applied to the second component based on one or more of the parameters determined from the first component. For example, one or more values of the operating parameters of the ion transmission device (such as the amplitude of the applied AC potential) may be measured or otherwise determined by a controller in the apparatus. Based on this determination, one or more suitable values may be applied to the operating parameters of the ion source by the controller, thereby coordinating both sets of operating parameters with respect to each other. The foregoing coordination method of the present invention may also be performed unidirectionally, reciprocally, or any other suitable combination thereof. For example, one or more operating parameters may be determined on both components, and based on this determination, the controller may apply suitable operating parameters on the other components. Further to the above, in some embodiments of the present invention, coordination of the respective operating parameters may require monitoring the component for changes to its operating parameter values. Such monitoring may be performed in real-time, at periodic intervals, or at other suitable times or intervals. In these embodiments, changes to one or more of the operating parameter values of a first component may result in a coordinate changes of one or more of operating parameter values of the other component. For example, the controller may monitor one or more of the operating parameter values of the ion transmission device. If the controller determines that the values of one or more of these parameters (e.g., the AC potential applied to the ion transmission device) has changed, the controller may apply a coordinate change in the values of the operating parameters of the other component (e.g., the ion source). In some embodiments of the present invention, coordination of the respective operating parameters may require applying suitable operating parameter values to both the ion source and the ion transmission device in a coordinate yet independent manner. Such coordination may not require determination of the operating parameter values of one or both components, but instead the respective operating parameter values may be matched prior to their application, and applied to both respective components coordinately. For example, the controller may include a lookup table or other suitable database in which each given set of ion source operating parameters is matched with a corresponding set of ion transmission device parameters. Such operating parameter values may have been predetermined, newly calculated from other values, or other suitable combinations thereof. In some embodiments of the present invention, one or more values of the operating parameters that are applied to the ion source and ion transmission device may be calculated or derived by other suitable mathematical or logical systems. These calculated operating parameter values may be thus derived from one or more other operating parameter values. For example, to coordinate the respective operating parameters of the ion source and the ion transmission device of the present invention, one or more values of the operating parameters (e.g., the peak amplitude of the applied AC potential) may be determined by querying or measuring the ion transmission device. The controller may then calculate or otherwise derive one or more of values of the ion source operating parameters based on one or more of the values of the ion transmission device operating parameters. In some embodiments of the present invention, one or more values of the operating parameters applied to the ion source and the ion transmission device may be predetermined. In such embodiments, such predetermined operating parameters may not require real-time calculations or logical transformations by the controller. Predetermined operating parameter values may be generated by calculating the operating parameters in advance, and then pre-loading or storing the values in the controller for subsequent retrieval and application to the component. Other suitable methods for predetermining operating parameter values may include empirical observation of and experimentation with the component in question. Predetermined operating parameter values may be determined based on computer simulations of the components under simulated operating conditions. It is also within the scope of the present invention that the operating parameter values may be determined by ascertaining a mathematical or other algorithmic relationship between the desired operating parameters and other known operating parameters. It is also within the scope of the present invention that, with respect to any of the foregoing methods, such determination may make determination of operating parameters more efficient by reducing the degrees of freedom among the known operating parameters. Predetermined operating parameters calculated by these methods may then be stored in memory storage of the controller such that the calculated does not need to be performed again. In some embodiments of the present invention, coordination of the respective operating parameter values may be performed over several intervals. For example, a first set of operating parameter values may be applied to a first component (e.g., the ion transmission device) and a corresponding first set of operating parameter values may be applied to a second component (e.g., the ion source). These first sets may be maintained on each component for a period of time. The length of a period may be fixed or predetermined, or may be conditioned on other events. Following this period, a second set of operating parameter values may then be applied to the first component and a corresponding second set of operating parameters may be applied to the second component. This continued coordination of the respective operating parameters may continue to be maintained for many intervals or periods of time. In some embodiments, coordination of the respective operating parameters of the first and the second components may involve synchronizing the respective operating parameter values. In some other embodiments, such coordination may be offset by a suitable time period or other criteria. For example, a given set of operating parameter values may be applied to a first component, and a corresponding set of operating parameter values may be applied to a second component following a period of time after the first application. In some embodiments, this temporal order may be reversed. The temporal offset may be predetermined, or may be responsive to the certain parameters. For example, a set of operating parameters may be applied to an ion source to allow ions of a certain mass range to be extracted. After a period of time to allow these ions to travel to the entrance of the ion transmission device, the corresponding set of operating parameter values may then be applied to the ion transmission device, thereby effecting coordination of the respective operating parameter values in accordance with the present invention. In one embodiment, an apparatus may include an ion source with a plurality of electrodes in ion communication with an ion transmission device, which is an multipole radio-frequency ion guide (RFIG). In this embodiment, coordination of the operating parameter values of an ion source with operating parameter values of the multipole RFIG may include setting one or more values for the AC potentials applied to the multipole RFIG electrodes. Based on these values applied to the RFIG, the potentials applied to one or more of the ion source electrodes may be set. In certain conditions, this coordination of the operating parameter values of the ion source with the operating parameter values of the multipole RFIG results in an improved or increased ion current from the RFIG, compared. Coordination of the respective values may also include the situation in which one or more of the operating parameter values are changed on the multipole RFIG. For example, the RFIG may be ramped, thereby changing the peak amplitude of the AC potential applied to its electrodes. In response to this change of values in the RFIG, one or more of the operating parameter values of the ion source may also be changed. For example, the potentials applied to one or more of the ion source electrodes may also be changed in response to the change in values of the RFIG. Therefore, coordination of the respective operating parameter values in this manner in accordance with the present invention may result in changing the respective values in a substantially synchronous manner. In accordance with methods and apparatus of the present invention, control of the ion current of the ion transmission device may result in useful improvements to the ion current in the ion transmission device compared to prior practices. For example, previously when a predetermined set of operating parameters had been applied to the ion source, these operating parameters were generally not changed during the operation of the apparatus, nor were they changed or coordinated with the operating parameters of other components, such as that of the ion transmission device. Accordingly, improvements of the present invention resulting from coordination of the respective operating parameters may be at least one-and-one-half-fold, at least two-fold, at least three-fold, or at least-five fold over an apparatus or methods in which the ion source operating parameters have not been coordinated with the ion transmission device operating parameters. Similarly, in some embodiments such improvements in the ion current may also result in commensurate or proportional improvements in the ion-derived signal measured by the apparatus. For example, in an apparatus of the present invention that includes a TOF mass analyzer, improvements in the ion current resulting from the methods and apparatus described herein may also increase the signals and amount of detected ions by the TOF apparatus. Coordinating respective operating parameters in accordance with the present invention may be used to control other aspects of the ion current, other than improvement of the ion flux. For example, control of the ion current may be used to increase ion flux with respect to one or more selected ion species, to decrease ion flux with respect to one or more selected species, to enrich one or more ion species, to diminish one or more ion species, to control the distribution of velocities (with respect to either or both of the magnitude or directions) of the ion current, and any other suitable properties of the ion current or suitable combinations thereof. Coordination of the operating parameters of an ion source and an ion transmission device, in accordance with the present invention, has several advantages and differences over previous methods and apparatus. First, in contrast to previous methods, coordinating the respective operating parameters may provide values for the operating parameters that are suitable for controlling the ion current of the ion transmission device. Previously, controlling the ion current of the ion transmission device was not considered when setting the operating parameters of other components, in particular the operating parameters of the ion source. Second, in contrast to previous methods, coordination of the operating parameters in accordance with the present invention may require setting or providing values for the operating parameters for one component (e.g., the ion source) based on the operating parameters of another component (e.g., the ion transmission device). For example, one or more values of the operating parameters of an ion transmission device may be determined. Based on this determination, a corresponding set of operating parameters may then be applied to the ion source. Previously, operating parameters for one component were usually set to affect functionality of that component, and not necessarily the functionalities of other components. Third, in contrast to previous apparatus, the present invention includes a controller component suitable for and configured to coordinate the respective operating parameters of the ion source and the ion transmission device. Previous apparatus lacked such a controller, and particularly one configured for coordinating the respective operating parameters of the two components. More particularly, previous apparatus lacked a controller configured to effect such coordination in order to effect control of the ion current in the ion transmission device. Fourth, in contrast to previous methods and apparatus, operating parameters for one or more components of an apparatus of the present invention may be predetermined and subsequently stored. Accordingly, during coordination of the respective operating parameters, the stored, predetermined operating parameters may be applied to their respective components. Storing and using predetermined operating parameters in the present invention may be particularly useful when mutually coordinated sets of operating parameters may be too complex or time-consuming to calculate in real-time. In another aspect, the present invention may provide an apparatus for controlling the ion current of an ion transmission device. Such apparatus of the present invention may effect this ion current control by coordinating the operating parameters applied to the ion source with that of the ion transmission guide, both of the present invention. Referring to FIG. 15, a block diagram of an embodiment of an apparatus of the present invention is depicted. Apparatus 105 may comprise ion source 110 and ion transmission device 120. Ion source 110 is in ion communication with ion transmission device 120, such that ions may travel from the ion source to the ion communication device. Apparatus 105 of the present invention may also include optional intervening component 130 disposed between ion source 110 and ion transmission device 120. If present, intervening component 130 is in ion communication with both ion source 110 and ion transmission device 120, thus allowing ions from ion source 110 to enter ion transmission device 120 via intervening component 130. Likewise, optional intervening component 135, if present, may be disposed following ion transmission device 120 in a manner similar to intervening component 130, such that ions may travel from ion transmission device 120 and distal component 140 via intervening component 135. If either or both are present, intervening components 130 and 135 may include, for example, deflecting electrodes (having static or dynamic applied potentials), electrostatic lenses, apertures, mass filters, ion transmission devices, cooling cells, collision cells, ion fragmentation cells, mass analyzers, multipole devices, ion guides, and other like devices or suitable combinations thereof. Intervening components 130 and 135 may serve to limit or restrict the entry to or exit from components of apparatus 105 to which they are proximately situated. Intervening components 130 and 135 may also serve to affect the potentials or electromagnetic environment of ions. Intervening components 130 and 135 may also effect other changes to the ions, such as mass- or charge-dependent filtration or selection of ions, fragmentation, redirection or deflection, reduction in kinetic energy (i.e., cooling), linear or angular acceleration, and other suitable or necessary functions as are known in the art. Apparatus 105 of the present invention also includes distal component 140 that is capable of receiving ions from ion transmission device 120, or via intervening component 135, if present. Distal component 140 may include one or more mass analyzers, one or more mass spectrometers, a total ion current measuring device, an ion mobility spectrometer, and other like devices known in the art, as well as suitable combinations thereof. In the present invention, the ion current of the ion transmission device may affect the quantity and distribution of ions that are received by the distal component. The present invention also embraces embodiments of apparatus 105 in which distal component 140 is optional. In such embodiments, apparatus 105 of the present invention minimally may comprise ion source 110, ion transmission device 120, and controller 150. Such an apparatus may serve as a particularly useful and improved means for generating ions with an improved ion current. Apparatus 105 of the present invention also includes ion detector 160, which may include an ion detector for detecting ions, and may also include a component for amplifying ion signals, examples of which are known in the art, and thus will not be discussed in detail here. For example, ion detector 160 may include continuous electron multipliers, discrete dynode electron multipliers, scintillation counters, Faraday cups, photomultiplier tubes, and the like. Ion detector 160 may also include a system or component for recording ions detected therein, such as a computer or other electronic apparatus. In some embodiments of the present invention, apparatus 105 may be a single-stage mass spectrometer apparatus. In such embodiments, mass analysis is performed by a mass analyzer included within distal component 140. Suitable mass analyzers include, for example, a quadrupole mass filter, a reflectron, a time-of-flight mass analyzer, an electric sector time-of-flight mass analyzer, a triple quadrupole apparatus, a Fourier transform ion cyclotron resonance mass analyzer, a magnetic sector mass analyzer, or other suitable mass analyzers known in the art. In some embodiments of the present invention, apparatus 105 may be a tandem mass spectrometer, whereby apparatus 105 may comprise two or more mass analyzers. In some tandem mass spectrometer embodiments of the present invention, distal component 140 of apparatus 105 may include the one or more mass analyzers. For example, distal component 140 can be selected from the group consisting of a quadrupole-TOF MS, an ion trap MS, an ion trap TOF MS, a TOF-TOF MS, a Fourier transform ion cyclotron resonance MS, with an orthogonal acceleration quadrupole-TOF MS a particularly useful embodiment. In other embodiments, both ion transmission device 120 and distal component 140 may each include one or more mass analyzers. For example, ion transmission device 120 may include a first mass analyzer and distal component 140 may include a second mass analyzer. In some of such embodiments, the first mass analyzer is ion transmission device 120. In other of such embodiments, ion transmission device 120 may include one or more mass analyzers and one or more ion guides, whereby the mass analyzers and ion guides function together as ion transmission device 120. Control of ion transmission device 120 by controller 150 may be effected by control of one or more of said mass analyzers and ion guides. In one example of an apparatus of the present invention having multiple mass analyzer components, apparatus 105 may comprise a suitable ion source as ion source 110, one or more multipole (e.g., quadrupole) ion guides and/or mass filters as ion transmission device 120, and a time-of-flight mass analyzer as distal component 140. In another example, apparatus 105 may comprise a suitable ion source as ion source 110, one or more multipole (e.g., quadrupole) ion guides and/or mass filters as ion transmission device 120, and a Fourier transform ion cyclotron resonance mass analyzer as distal component 140. Apparatus 105 of the present invention also includes controller 150 which is configured to coordinate the operating parameters of ion source 110 and ion transmission device 120. Controller 150 may be in signal communication with ion source 110 and ion transmission device 120. Such signal communication may occur by either or both analog or digital signals. In some embodiments, controller 150 may include one or more digital computers, including a processor and memory storage. Controller 150 may also be configured to store values of operating parameters, such as predetermined operation parameters or those determined from one or more of the components of the apparatus. In some embodiments of the present invention, controller 150 may be configured to provide one or more values for the operating parameters of ion source 110. Similarly, controller 150 may also be configured to provide one or more values for the operating parameters of ion transmission device 120. In addition, in some embodiments of the present invention controller 150 may also be configured to determine one or more of the operating parameters of either or both of ion source 110 and ion transmission device 120. Such determination may be made by, for example, measuring or otherwise deriving the parameter to be determined from the device or its immediate controller, querying the device or its immediate controller for the desired parameter, determining the desired parameters based on the parameters that were recently provided to the device, and other suitable methods or combinations thereof as are known in the art. Ion source 110 includes any systems or methods for generating ions that are known in the art. Ions may be generated in ion source 110 in a continuous or pulsed manner. Ion source 110 may include means for producing a plurality of ions within a relatively small volume and within a relatively short time. Also included are any of the systems or methods known in the art for producing a pulse of ions, such that the pulse of ions has the appearance of or behaves as if the ions were produced within a relatively small volume and within a relatively short time. Ion source 110 may also include systems or methods for producing a continuous beam of ions, or by any of the known systems or methods of producing an essentially continuous or extended beam of ions from an initially generated pulse of ions. Ion source 110 may also include systems or methods to concentrate the ions, such as a quadrupole ion trap, a linear ion trap, and other suitable systems or combinations thereof. Ion source 110 may, for example, include systems or methods that employ a pulsed laser interacting with a solid surface, a pulsed focused laser ionizing a gas within a small volume, or a pulsed electron or ion beam interacting with a gas or solid surface. In another example, ion source 110 may employ systems or methods for generating a pulse of ions that uses a rapidly sweeping, continuous ion beam passed over a narrow slit, in which a brief pulse of ions is produced by the ions passing through the slit when the ion beam passes thereover. Ion source 110 may employ, but is not limited to use of, electrospray ionization, laser desorption/ionization (“LDI”), matrix-assisted laser desorption/ionization (“MALDI”), surface-enhanced laser desorption/ionization (“SELDI”), surface-enhance neat desorption (“SEND”), affinity capture laser desorption/ionization, fast atom bombardment, surface-enhanced photolabile attachment and release, pulsed ion extraction, plasma desorption, multi-photon ionization, electron impact ionization, inductively coupled plasma, chemical ionization, atmospheric pressure chemical ionization, hyperthermal source ionization, and the like. Furthermore, ion source 110 may also include systems or methods for selectively providing ions of one or more masses or ranges of masses, or fragments therefrom. Such systems or methods may be accomplished by combining the apparatus of the present invention in tandem fashion with a mass analyzer that is known in the art, wherein the mass analyzer may include components such as magnetic sectors, electric sectors, ion traps, multipole devices, mass filters, TOF devices, and the like. The combined mass analyzer and ion source may be included as part of ion source 110. Ion source 110 may also include systems or methods for extracting or accelerating ions from the ion source, such as by application of an electric field or voltage pulse. Such systems or methods may be parallel (i.e., coaxial) or orthogonal with respect to the trajectory of the initially-generated ions, such as an ion beam. Extraction or acceleration of the ions may occur subsequent to the formation of the ions. Ion source 110 may also include systems or methods for reducing the initial kinetic energies of the ions that may result from their desorption or ionization, such as by collisional cooling means. Accordingly, ion source 110 may also include a gas flow field, as is known in the art. Ion source 110 may, in certain embodiments, use superposed electrostatic and gas flow fields, as further described and claimed in the commonly owned patent application, entitled “Ion Source With Controlled Superposition Of Electrostatic And Gas Flow Fields” the disclosure of which is incorporated herein by reference in its entirety. The advantages of the present invention become particularly apparent when such ion sources are used. In these embodiments, ion motion is determined by a multitude of factors, including the initial conditions, the ion mass, the collision cross-section, the spatial distribution of the gas flow velocity vector field, the spatial distribution of the gas flow pressure field, and other like conditions. Accordingly, methods and apparatus of the present invention may allow control and improvement of the total ion current over a wide mass range in these embodiments. Referring to FIG. 16, an exemplary ion source embodiment of the present invention is depicted. Ion source 205 is depicted schematically in cross-sectional view, in which the vertical axis corresponds approximately to the longitudinal ion extraction path. It is understood that the particular number, arrangement, shapes, configuration and other features of the ion source and its electrodes as depicted in ion source 205 and described herein are an exemplary embodiment of the present invention provided for illustrative purposes. Other conceivable ion source configurations, including those known in the art, are envisioned to be included within the scope of the present invention. Like ion source 105 in FIG. 15, ion source 205 may be in ion communication with ion transmission device 290 via ion source exit 220, either directly or via optional intervening components, such as those described herein. Accordingly, ions that exit via ions source exit 220 may be received by and thereby may enter ion transmission device 290. In ion source 205, ions are generated at or near ion generation point 210, such as by laser desorption/ionization or other suitable ion generation systems or methods, including those listed herein. Ions generated at point 210 may have initial thermal energies resulting from the desorption, ionization, or other step during or following generation of the ions from the sample. In the exemplary embodiment of the present invention depicted in FIG. 16, ion source 205 includes basal electrode 230 and electrodes 240-255. Electrodes 230-255 preferably have an axisymmetric configuration, but may also comprise discrete electrode elements. Operating parameters of these electrodes may include, for example, direct current (DC) potentials, alternating current (AC) potentials, or any other arbitrarily time-dependent waveform or suitable combinations thereof may be applied independently to each of these electrodes such that each electrode may have different potential values. Another operating parameter is the waveform of the applied potentials. The applied potentials may also have an arbitrary waveform, such as sinusoidal, square, sawtooth, and other suitable forms. As a result of these applied potentials, each electrode may affect the potential experienced by ions within ion source 205. In preferred embodiments of the present invention, the electric field resulting from electrodes 230-255 is configured to accelerate and direct ions towards ion source exit 220. In this embodiment, other operating parameters of ion source 205 may include, for example, the magnitude and timing of potentials applied to one or more of electrodes 230-255. Still other operating parameters may include the physical locations of one or more of the electrodes within the ion source, parameters relating to any time-dependent application of potentials to one or more of the electrodes, parameters relating to the generation of the ions or introduction of the sample, and other suitable operating parameters of ion sources that are known in the art. Control of one or more the foregoing ion source operating parameters may be effected by, for example, controller 260 in signal communication with ion source 205. Controller 260 may thereby apply or set one or more of the operating parameters of ion source 205. Controller 260, or another suitable device, may also be configured to determine one or more of the current operating parameters of ion source 205 (as described above), such as by measuring, querying, or deriving said parameters from ion source 205. An apparatus of the present invention also includes an ion transmission device, such as ion transmission device 120 and 290 represented in FIGS. 15 and 16, respectively. An ion transmission device of the present invention serves to conduct one or more ions from its entrance to its exit. The entrance of an ion transmission device of the present invention may be in ion communication with an ion source, such as ion source 110. The exit of an ion transmission device of the present invention may be in ion communication with a distal component or mass analyzer, such as distal component 140. Referring to FIG. 15 as an example, ions that exit ion source 110 of the present invention may then enter ion transmission device 120 (either directly or via an optional intervening component). Ion transmission device 120 may then conduct the ions to subsequent distal component 140 (either directly or via an optional intervening component). In some embodiments of the present invention, the distal component includes one or more mass analyzers and ion detectors. As described hereinabove, it is understood that the present invention embraces embodiments in which distal component 140 is optional, such that apparatus 105 minimally may comprise ion source 110, ion transmission device 120, and controller 150. One operational metric of the ion transmission device is its ion current. Ion current may generally refer to the flux of ions (or other charged species) at a given point or through a given cross-section in an ion path. Ion current can reflect the total flux of all ions, irrespective of ion mass. Under certain circumstances, it may be more useful to determine partial ion current as a function of ion mass. Partial ion currents may be particularly useful to identify and to measure mass-dependent selectivity and preferences within the apparatus. For example, an ion transmission device in the apparatus according to the present invention may exhibit a mass-dependent selectivity when conducting ions therethrough. To demonstrate such selectivity, a partial ion current can be measured for each mass or range of masses as ions enter and exit the device. Ion masses to which the ion transmission device exhibits either positive or negative selectively may result in a higher or lower corresponding partial ion current at the exit of the device. The ion current of an ion transmission device in the apparatus according to the present invention reflects the ion flux at the exit of the ion transmission device. Using apparatus 105 in FIG. 15 as an example of the present invention, the ion current of ion transmission device 120 therefore reflects the flux, or amount, of ions exiting ion transmission device 120. Accordingly, this ion current may also reflect the ion flux, or amount of ions, that is entering distal component 140 (either directly or via optional intervening component 135). The ion current of the ion transmission device may be particularly relevant with respect to components that are distal from the ion transmission device, and thus are capable of receiving ions therefrom. In preferred embodiments, these components may include a mass analyzer and ion detector. Accordingly, the ion current can be an important indicator of the operating performance of the apparatus. For example, in some embodiments of the present invention, distal apparatus 140 of FIG. 15 may include a time-of-flight (TOF) mass analyzer. A TOF mass analyzer is capable of receiving and measuring individual ions over a broad range of masses, in which the signal strength for each ion may correspond to the amount of that ion received by the analyzer. In such cases, high ion currents are preferable to low ion currents, as the former may result in a stronger signal by the mass analyzer. Therefore, it is desirable in these and other contexts to improve the ion current over all ion masses. Ion transmission device 120 of FIG. 15 may include any suitable device for conducting or transmitting ions that are known in the art. Examples of ion transmission devices may include ion guides, multipole devices (such as quadrupoles, hexapoles, octopoles, etc.), electrostatic ion guides, electromagnetic ion guides, and other like devices or combinations thereof. Ion transmission device 120 may include a plurality of such devices arranged in serial ion communication. For example, ion transmission device 120 may include a triple-quadrupole device, as is known in the art, in which three quadrupoles (a first mass filter, a collision cell, and a second mass filter) are arranged in series. In some embodiments of the present invention, ion transmission device 120 may include one or more ion guides, as are known in the art. Ion guides are suitable for conducting one or more ions from its entrance to its exit. In some embodiments, ion guides of the present invention are configured to confine and focus an ensemble of mobile ions within a potential envelope. In this manner, only those ions that can maintain a stable trajectory within the ion guide are then able to exit the ion guide. In some ion guide embodiments, conduction by the ion guides is performed by reducing or dampening the ion velocity components that are orthogonal to the longitudinal axis of the ion guide, while substantially maintaining the parallel component. In this manner, ions that exit the ion guide are more focused in a single direction. Ion guides of the present invention may include, for example, multipole ion guides, electrostatic ion guides, electromagnetic ion guides, and other suitable ion guides and combinations thereof as are known in the art. In some preferred embodiments of the present invention, ion transmission device 120 may include one or more multipole ion guides, as are known in the art. Multipole devices are constructed from a plurality of linear electrodes. The linear electrodes are uniformly and circumferentially arranged around a central longitudinal axis. The electrodes are also arranged such that they are parallel with respect to each other and the central axis. The approximately cylindrical shape of a multipole ion guide thereby defines a longitudinal passage through which the ions are conducted. The individual electrodes in multipole ion guides of the present invention may have cylindrical, hyperbolic, or other suitable cross-sectional geometries, as are known in the art. In some preferred embodiments of the present invention, ion transmission device 120 may include one or more multipole ion guides having four, six, or eight electrodes (known respectively as quadrupoles, hexapoles, and octopoles), as are known in the art. In some embodiments of the present invention, ion transmission device 120 may include one or more segmented multipole devices. Such segmented multipoles may allow the application of different potentials to each segment. In some preferred embodiments of the present invention, ion transmission device 120 may include one or more quadrupole ion guides. Referring to FIG. 17, schematic isometric view of an exemplary quadrupole ion guide is depicted. Quadrupole 300 includes linear electrodes 310-325 arranged substantially in parallel with respect to each other. Electrodes 310-325 are also substantially parallel to and equidistant from longitudinal axis 330. Quadrupole ion guide 300 may also include one or more terminal electrostatic lenses at either or both of openings of ion guide 300, such as lenses 360 and 365. Lenses 360 and 365 may be disposed in a manner and at a location such that they may affect the potential experienced by ions entering or exiting the quadrupole. In some embodiments of the present invention, quadrupole ion guide 300 may also include potential sources 340 and 345. Potential sources 340 and 345 are configured to apply voltage potentials to one or more of electrodes 310-325. In some preferred embodiments of the present invention, potential source 340 is configured to apply potentials to electrode pair 310 and 315, while potential source is similarly configured to apply potentials to electrode pair 320 and 325. In these embodiments, each potential source applies substantially the same potentials to both members of an electrode pair. As is known in the art, multipoles, such as quadrupole 300, conduct mobile ions that are able to maintain stable trajectories within its electric field. The potentials applied to the electrodes from potential sources 340 and 345 may consist of a direct current (DC) potential with a superimposed alternating current (AC) potential. In quadrupole ion guide 300 of the present invention, the time-dependent potential of each electrode can be generally defined by the following equations:ΦA=+[ΦDC+ΦAC cos(ωt)] (Eq. 1)ΦB=−[ΦDC+ΦAC cos(ωt)] (Eq. 2) In the above general equations, ΦA (Eq. 1) represents the potential applied to electrodes pairs 310 and 315 by potential source 340. Similarly, ΦB (Eq. 2) represents the potential applied to electrodes pairs 320 and 325 by potential source 345. Application of the potentials to each pair of electrodes in accordance with Eqs. 1 and 2 results in a phase-shift with respect to each other by approximately 180°. The waveform of the applied AC potentials is generally sinusoidal, but may also be sawtooth, square, or any other known waveform or suitable combination thereof. All of the foregoing are examples of operating parameters of an ion transmission device of the present invention The value of ΦDC represents the DC potential applied to the electrodes, while ΦAC represents the peak amplitude of a superimposed AC potential. The AC potential varies periodically as a function of time (t) with a frequency ω. The frequency of the applied AC potential is typically in the radio-frequency (MHz) range. Accordingly, such ion guides are known as radio-frequency ion guides (RFIG). A suitable AC frequency is primarily determined by the ion mass or mass range to be conducted, and the geometry of the multipole device. These and other suitable or relevant variables known in the art may be included in the operating parameters of the ion transmission device of the present invention. Similarly, operating parameters may also include other appropriate values for other suitable ion transmission devices of the present invention. Control of one or more of the foregoing operating parameters of the ion transmission device may be effected by, for example, controller 350 in signal communication with ion transmission device 300. Controller 350 may thereby apply or set one or more of the operating parameters of ion transmission device 300. Controller 350, or another suitable device, may also be configured to determine the current operating parameters or state of ion transmission device 300, such as by measuring, querying, or deriving said parameters from ion transmission device 300. The oscillating AC potential applied to the multipole device, such as quadrupole 300, creates a dynamic electric field environment. For a given AC peak voltage, AC frequency, and quadrupole geometry, ions of a certain mass range can maintain stable trajectories and are thereby conducted to the exit of the multipole. Other species, such as those with unstable trajectories or non-charged species, will fail to be conducted to the exit and will exit the multipole at other locations. In preferred embodiments of the present invention, quadrupole 300 of FIG. 17 functions as a multipole ion guide. In such a multipole ion guide, only the AC potential component is applied to the electrodes, whereas the DC potential component (i.e., (DA in Eqs. 1 and 2) is essentially zero. Accordingly, for multipole ion guides the generalized equations above may be reduced to the following equations:ΦA=+ΦAC cos(ωt) (Eq. 3)ΦB=−ΦAC cos(ωt) (Eq. 4) Multipole ion guides still exhibit some mass selectivity, although significantly lower than that of a mass filter, and thereby conduct a broader range of ions masses. In certain embodiments and applications of the present invention, such broad permissibility of ion transmission is preferable and advantageous. For example, a multipole ion guide that provides a broad range of ion masses is preferable when the ions exiting the ion transmission device are subject to subsequent mass analysis, such as by a time-of-flight mass analyzer. Therefore, it is even more preferable under these and other circumstances to have an even broader range of ion masses transmitted by the ion guide. Accordingly, it is desirable to improve upon even the lower mass selectivity of the multipole ion guide. In some embodiments of the present invention, quadrupole 300 of FIG. 17 functions as a multipole mass filter. In such a mass filter, the applied potential has non-zero DC and AC potential components concurrently applied to the electrodes. In multipole mass filters, in contrast to multipole ion guides described above, only a relatively narrow range of ion masses can achieve stable trajectories within the multipole device. As a result, this narrow range of ion masses is thereby selected for conduction by the multipole mass filter. In an exemplary apparatus of the present invention, the apparatus includes a RFIG in ion communication with an ion source. The RFIG is a multipole ion guide having properties similar to ion guide 300 depicted in FIG. 17. The ion source includes systems or methods for the electrostatic extraction of ion therefrom, similar to ion source 200 depicted in FIG. 2. As described in further detail below, both the ion source and the ion transmission device of this exemplary apparatus exhibit mass-dependent behavior that may result in selective transmission of the affected ion population. Previous methods and apparatus were significantly limited in their ability to remedy this problem. In contrast, methods and apparatus of the present invention provide improvement and advantages over these earlier approaches. As a result of this mass-dependent behavior of the RFIG, the population of ions in the ion current exiting the ion transmission device may be less diverse and have lower partial ion currents than the ion population that enters the device. In certain applications of the present invention, such as time-of-flight mass analysis, this diminishment of the ion current may have considerable impact on the mass analysis results. For example, a poorer partial ion current may result in a lower TOF signal. The foregoing limitation may be partially addressed by “ramping” one or more appropriate parameters of the ion transmission device. In this technique, different sets of operating parameters are applied to the RFIG in sequence. For example, an AC potential having a peak amplitude of ΦAC_1 is applied to the RFIG over a first period of time. Following this first period, a peak amplitude of ΦAC_2 is applied in a second period. Other additional intervals in which different operating parameters are applied to the RFIG may follow in a like manner. In each interval, a different range of ion masses may be stably conducted by the RFIG. By allowing the RFIG to operate under multiple operating parameters, the RFIG may cumulatively conduct a broader range of ion masses than would be possible under a single set of operating parameters. As a result, the cumulative ion current of the ion transmission device may be improved accordingly. FIGS. 18 A-D illustrate, in principle, a prophetic example of mass selectivity in a representative RFIG of the present invention. In this example, the distributions of ion masses (i.e., m1, m2, and m3) that are conducted by the RFIG at three different peak AC amplitudes (i.e., ΦAC_1, ΦAC_2, and ΦAC_3) are shown. In FIG. 18A, an exemplary time-course of the peak AC amplitude as applied to an RFIG is shown. In a first time interval, when the peak AC amplitude is ΦAC_1, the RFIG conducts a mass range of ions distributed around mass m1, as shown in FIG. 18B. Likewise in FIG. 18C, when the RFIG is ramped to ΦAC_2 during a second time interval, a different mass range, now centered around mass m2, is preferably conducted. At a third time interval, the peak AC amplitude of ΦAC_3 results in the conduction of the mass range m3 as shown in FIG. 18D. Repeating this ramping cycle, such as by reapplication of the ΦAC_1 peak amplitude to the RFIG, results again in conduction of mass range m1. As a result, there is no single set of ion guide operating parameters, such as a value for ΦAC, at which the RFIG can conduct efficiently the entire range of ion masses that are shown in FIGS. 18B-18D. However, certain heretofore unaddressed shortcomings remain despite the use of ramping. Most significantly, ramping the ion transmission device may not improve partial ion currents if the precedent ion source providing the ions is the limiting factor. For example, if the preceding ion source provides only a narrow range of ion masses to the ion transmission device, ramping the RFIG to allow conduction of ions outside of this narrow range will not result in improved ion current for that mass range. Moreover, the above limitation of the ion source is particularly apparent because of the demonstrated mass dependence of ion sources. For example, in ion sources in which ions are extracted electrostatically, ions are not extracted with uniform efficiency. Other ion sources may also demonstrate such mass dependence and therefore behave in a similar manner. An example of this ion source behavior is described below. Referring to FIGS. 19A-C, an exemplary ion source of the present invention is depicted. Ion source 205 (as described above in relation to FIG. 16) includes electrodes 230-255. Ions are generated at introduction point 210 and are intended to exit via ion exit 220 in order to proceed to subsequent devices. In certain embodiments of the present invention, an ion transmission device including a RFIG may be positioned to receive ions exiting the ion source. Each of FIGS. 19A-C depicts simulated ion trajectories within the ion source of the present invention. For the ion source in each figure, a set of operating parameters have been applied to the ion source, specifically a set of DC potentials that have been applied to each of the ion source electrodes. Under these conditions, a plurality of ions are introduced at approximately introduction point 210 and, as a result, undergo deflection and other accelerations subject to the imposed electric field and, if present, collisions with a background gas. In this stochastic model, the efficiency of ion extraction at ion exit 220 can be assessed based on the number of simulated ion trajectories that exit successfully via ion exit 220. The simulation depicted in FIGS. 19A-C were performed using methods such as those described in the following references: Andreas Hieke, “GEMIOS—a 64-Bit multi-physics Gas and Electromagnetic Ion Optical Simulator”, Proceedings of the 51st Conference on Mass Spectrometry and Allied Topics (Jun. 8-12, 2003, Montreal, PQ, Canada); Andreas Hieke “Theoretical and Implementational Aspects of an Advanced 3D Gas and Electromagnetic Ion Optical Simulator Interfacing with ANSYS Multiphysics”, Proceedings of the International Congress on FEM Technology, pp. 1.6.13 (Nov. 12-14, 2003, Potsdam, Germany); Andreas Hieke, “Development of an Advanced Simulation System for the Analysis of Particle Dynamics in LASER based Protein Ion Sources”, Proceedings of the 2004 NSTI Nanotechnology Conference and Trade Show Nanotech 2004 (Mar. 7-11, 2004, Boston, Mass., U.S.A). Other suitable programs, algorithms, methods, and the like that are known in the art may also be used to perform simulations such as those described herein. As set forth in Table 1, the simulation was conducted with the listed potential values applied to the corresponding electrodes, while simulating the trajectories of ions having the listed mass. TABLE IFIG. 5AFIG. 5BFIG. 5CIon Mass m1000u10000u10000uPotential φ on40V40V70VElectrode 230Potential φ on52V52V122VElectrodes 240Potential φ on0V0V0VElectrodes 245Potential φ on40V40V70VElectrodes 250Potential φ on0V0V0VElectrodes 255 FIGS. 19A and 19B both depict ion source 205 under the same electrostatic and pneumatic conditions, as shown in Table 1. However, each of these figures illustrates the trajectories of a different ionic species. In FIG. 19A, trajectories of ions having mass m=1000 u are shown. In FIG. 19B, trajectories of ions having mass m=10000 u are shown. Referring to FIG. 19A, under the operating parameters listed in Table 1, the simulation predicts that nearly all of the ions having mass of 1000 u are expected to exit the ion source at exit 220. In contrast, FIG. 19B depicts that under the same set of operating parameters the ions having a mass of 10000 u are extracted with a significantly lower efficiency. Therefore, under these operational conditions, if a diverse population of ions of varying mass were introduced into ion source 205, those having mass 1000 u are more efficiently extracted than those of mass 10000 u). As a result of this mass-dependent efficiency of ion extraction at the ion source, such differences may be propagated to later components, such as an RFIG in an ion transmission device. Accordingly, the partial ion current of the heavier ions (i.e., those around 10000 u) is expected to be lower than that of the lighter ions (i.e., those around 1000 u). Furthermore, because this difference originates in the ion source, ramping or otherwise changing the operating parameters of the subsequent RFIG may not significantly improve the partial current. However, the simulations reveals a different result in FIG. 19C. In this figure, a different set of DC potentials have been applied to ion source 205. Under this different set of operating parameters, ions having a mass of 10000 u are now extracted with a much greater efficiency. These simulations demonstrate that these and other ion sources exhibit a mass dependency during ion extraction. Therefore, if ions of a particular mass range are desired, the yield of such ions can be improved by changing the operating parameters of the ion source. However, despite this mass dependency of the ion source, ion source operating parameters were not previously changed during its operation of the apparatus. Instead, the operating parameters that were applied to the ion source were maintained regardless of the ion current and the operating parameters of the subsequent ion transmission device. As is evident from the examples provided in FIGS. 19A-C, no single set of operating parameters of the ion source is suitable for all ion masses. Therefore, even if the RFIG of the ion transmission device were ramped to cover a broader mass range, such practices were not completely effective because the ion source was often not providing ions of suitable masses. The methods and apparatus of the present invention solves these and other problems. By coordinating the respective operating parameters of both the ion source and the ion transmission device, the present invention may ensure that the ions provided by the ion source are commensurate with the ions conducted by the ion transmission device. For example, a RFIG included in an ion transmission device of the present invention is configured with operating parameters such that it preferentially conduct ions of a particular mass range. In accordance with the present invention, this set of RFIG operating parameters is coordinated with a set of corresponding operating parameters that are applied to the ion source. As a result of this coordination, the ion source is configured to efficiently extract and thereby provide ions having substantially the same particular mass range as those preferentially conducted by the RFIG. This coordination, therefore, may result in a significantly improved ion current for the particular mass range of ions. In a further example in accordance with the present invention, a different set of operating parameters may now be applied to the RFIG, thereby resulting in the preferential conduction of a different mass of ions. Such changes occur during the practice of ramping, as described above. To maintain coordination in accordance with the present invention, a second set of operating parameters is now applied to the ion source, whereby the second set corresponds to the second set applied to the RFIG. Under this second set of operating parameters, the ion guide may now provide a different mass range of ions that matches those now being conducted by the RFIG. Therefore, the present invention provides a significant improvement to the practice of ramping the RFIG of an ion transmission device. For example, at each ramping interval of the RFIG, the ion source may be correspondingly reconfigured with applied operating parameters such that the masses or other characteristics of the ions provided by the ion source match those that are to be conducted by the RFIG. This method of the present invention may therefore increase the ion current over a broad range of masses, particularly when compared to ramping the RFIG alone. An example of coordinating the operating parameters of different components, in accordance with the present invention, is depicted in FIGS. 18E-J. These FIGS. 18E-J illustrate, in principle, a prophetic example of coordination of a RFIG and an ion source, in conjunction with a prophetic example of resulting mass selectivity. In the example of FIGS. 18G-J, as described above in relation to FIGS. 18A-D, the distributions of ion masses (i.e., m1, m2, and m3) that are conducted by the RFIG at three different peak AC amplitudes (i.e., ΦAC_1, ΦAC_2, and ΦAC_3) are shown. FIG. 18G shows an exemplary time-course of the peak AC amplitude as applied to an RFIG. FIGS. 18E and 18F show concurrent time-courses of representative DC potentials (i.e., Φ1 and Φ2) applied respectively to two discrete electrodes within an ion source. In accordance with the present invention, the potentials applied to each of the ion source electrodes (as shown in FIGS. 18E and 18F) are coordinated with the ramping of the RFIG (as shown in FIG. 18G). In this example, when ΦAC_1 is applied to the RFIG as shown in FIG. 18G, ion source electrodes are coordinated accordingly by the application of DC potentials Φ1_1 and Φ2_1, as respectively depicted in FIGS. 18E and 18F. In some embodiments, as described herein, the operating parameter values used in this coordination may be predetermined. In each following time interval, the change in ΦAC resulting from the ramping of the RFIG (as in FIG. 18G) is coordinated by changes to Φ1 and Φ2 (FIGS. 18F and 18G, respectively) in the respective ion source electrodes. This exemplary coordination may result in improved ion current for the mass range that are preferably conducted by the RFIG at each time interval. An example apparatus of the present invention is depicted in FIG. 20. Apparatus 600 includes ion source 610, RFIG 620, mass analyzer 640, ion detector 650, and controller 630. The ion source, the RFIG, the mass analyzer, and the ion detector are in sequential ion communication. In certain embodiments of the present invention, mass analyzer 640 may include any suitable mass analyzer, such as a quadrupole mass filter, a reflectron, a time-of-flight mass analyzer, an electric sector time-of-flight mass analyzer, a triple quadrupole apparatus, a Fourier transform ion cyclotron resonance mass analyzer, a magnetic sector mass analyzer, or other suitable mass analyzers known in the art. Mass analyzer 640 may also be any suitable TOF apparatus known in the art, such as an electric sector TOF apparatus, a multi-electric sector TOF apparatus (such as a quadruple electric sector TOF apparatus), a reflectron, and other known TOF mass analyzers and suitable combinations thereof. RFIG 620 may include any known multipole ion guide known in the art, including quadrupoles, hexapoles, octopoles, and the like. Alternatively, or in addition, RFIG 620 may also include other suitable devices in serial ion communication with the RFIG, such as collision cells, electrostatic lenses, and the like. In some embodiments of the present invention, apparatus 600, like apparatus 105 of FIG. 15, may be a single-stage mass spectrometer apparatus, in which RFIG 620 serves as an ion guide without performing mass analysis. In some other embodiments of the present invention, apparatus 600, like apparatus 105 of FIG. 15, may be a tandem mass spectrometer, whereby apparatus 600 may comprise two or more mass analyzers. In some of such tandem mass spectrometer embodiments of the present invention, mass analyzer 640 of apparatus 600 may include a tandem mass analyzer. For example, mass analyzer 640 can be selected from the group consisting of a quadrupole-TOF MS, an ion trap MS, an ion trap TOF MS, a TOF-TOF MS, a Fourier transform ion cyclotron resonance MS, with an orthogonal acceleration quadrupole-TOF MS a particularly useful embodiment. In other tandem mass spectrometer embodiments of the present invention, both RFIG 620 and mass analyzer 640 may each include one or more mass analyzers. For example, RFIG 620 may include a first mass analyzer and mass analyzer 640 may include a second mass analyzer. In some of such embodiments, the first mass analyzer also serves to function as an ion transmission device of RFIG 620. In other of such embodiments, RFIG 620 further includes one or more mass analyzers and one or more ion guides, whereby said mass analyzers and ion guides function together as RFIG 620. For example, RFIG 620 may include a RFIG in serial communication with a quadrupole mass filter, an ion trap, or other mass analyzers as are known in the art. Alternatively, or in addition, in some embodiments mass analyzer 640 may include more than one mass analyzer components situated in tandem. A suitable tandem mass spectrometer can be selected from the group consisting of a quadrupole-TOF MS, an ion trap MS, an ion trap TOF MS, a TOF-TOF MS, a Fourier transform ion cyclotron resonance MS, with an orthogonal acceleration quadrupole-TOF MS a particularly useful embodiment Ion detector 650 which may include systems or methods for detecting ions and amplifying their signals that are known in the art. For example, ion detector 650 may include continuous electron multipliers, discrete dynode electron multipliers, scintillation counters, Faraday cups, photomultiplier tubes, and the like. Ion detector 650 may also include systems or methods for recording ions detected therein, such as a computer or other electronic apparatus Controller 630 is in signal communication with ion source 610 and RFIG 620. In this example, controller 630 is configured to determine one or more of the operating parameters of RFIG 620 and apply one or more of the operating parameters to ion source 610. In this exemplary embodiment, controller 610 determines, for example, the peak amplitude of the AC potential applied to RFIG 620. This set of operating parameters is thus coordinated with that of the ion source by applying a corresponding set of operation parameters to the ion source including, for example, one or more DC potentials applied to its electrodes. As described above, other conceivable controller configurations are envisioned to be within the scope of the present invention. For example, controller 630 may also be configured to determine one or more of the operating parameters of ion source 610, as well as apply one or more of the operating parameters to RFIG 620. In some embodiments, controller 630 may include a digital computer, a microprocessor, and memory storage. In some embodiments, the memory storage may be used to store values for operating parameters, including predetermined values used in coordination. In some embodiments, controller 630 may also include a plurality of such computers, wherein at least one computer is in communication with ion source 610 and at least one other computer is in communication with ion transmission device 620. In some embodiments, one or more of these separately communicating computers may be in communication with each other. Following this determination of the peak amplitude of the AC potential applied to RFIG 620, controller 630 may coordinate the operating parameters of ion source 610 with that of the RFIG. For example, the controller may coordinate the DC potentials applied to the electrodes of the ion source with the peak AC amplitude on the RFIG. Such coordination may also involve calculation of one or more values for operational parameters based on other operating parameters that have been determine or measured. In some embodiments, controller 630 may calculate the appropriate ion source operating parameters, use predetermined operating parameters, or suitable combinations thereof. In addition, predetermined operating parameters of ion source 610 may be derived from empirical observations, experimental determinations, computer-based simulations, mathematical calculations, and other suitable methods and combinations thereof. Referring to FIG. 21, a perspective cut-away view of a preferred embodiment of the present invention is depicted. Apparatus 700 of the present invention includes ion source 710, in which mobile ions are generated. Ion source 710 may include any suitable systems or methods for generating ions known in the art, including those described hereinabove with respect to ion sources 110, 205, and 610. In the configuration depicted in FIG. 7, ions are preferably introduced into or generated in the ion source at a location substantially near ion generation point 715. For example, ion generation point 715 may represent the point at which laser desorption/ionization occurs in suitable ion sources. Ion source 710 further may comprise basal electrode 730 and axisymmetric electrodes 735, 740, 745, and 750. Voltage potentials may be applied to some or all of these electrodes. The electric field resulting from these electrodes may affect the potentials experienced by the ions within the ion source. For example, potentials may be applied to the electrodes of ion source 710 in a manner such that ions are accelerated and deflected towards ion source exit 795. Voltage potentials on each of the ion source electrodes are applied by potential sources 733, 738, 743, 748, and 753 in the manner depicted. The foregoing potential sources may apply DC potentials, AC potentials, or any other arbitrarily time-dependent waveform or suitable combinations thereof to their respective electrodes. Apparatus 700 also includes ion transmission device 720 suitable for conducting mobile ions extracted and received from ion source 710 via ion source exit 795. In the preferred embodiment depicted in FIG. 7, ion transmission device 720 includes quadrupole radio-frequency ion guide 725, for which three of its electrodes are depicted (electrodes 780, 785, and 790). The fourth electrode has been omitted for purposes of clarity. Electrodes 780 and 785 are paired such that potential source 783 applies a common potential to both electrodes. Similarly, electrode 790 and the omitted electrode are commonly served by potential source 793. In accordance with the preferred invention, the respective operating parameters of ion source 710 and ion transmission device 720 are coordinated in order to effect control of the ion current. Such coordination may be performed by controller 760 in signal communication with one or more of the potential sources as shown. In an example, ions may be generated in ion source 710 at ion generation point 715. Application of a given set of operating parameters to electrodes 730, 735, 740, 745, and 750 can result in acceleration and extraction of ions of a given mass range towards ion source exit 795. Ions that exit in this manner can therefore enter multipole RFIG 725 of ion transmission device 720. Ion transmission device 720, having operating parameters that are coordinated with those of ion source 710, is configured to conduct ions having approximately the same or overlapping mass range. Accordingly, such ions are thereby conducted through multipole RFIG. Exemplary simulated ion trajectories within the ion source and the ion transmission device, as indicated by reference numeral 770, are depicted. In some embodiments, ion source 710 may use superposed electrostatic and gas flow fields, as further described and claimed in the commonly owned patent application filed concurrently herewith by Andreas Hieke, entitled “Ion Source With Controlled Superposition Of Electrostatic And Gas Flow Fields”, the disclosure of which is incorporated herein by reference in its entirety. In another aspect of the present invention, existing apparatus may be upgraded, retrofitted, or otherwise modified in accordance with the methods and apparatus of the present invention. For example, a prior or existing apparatus may lack a controller suitable for coordinating the ion source and the ion transmission device. Accordingly, it is envisioned that installing such a suitably configured controller would provide an apparatus in accordance with the present invention. In another embodiment, an existing apparatus may have a controller that is not configured for coordination operating parameters. In accordance with the present invention, this existing apparatus may thus be properly configured such that it is able to conduct configurations of operating parameters in the manner described above. In another embodiment, an existing apparatus may have a controller that is not configured for coordination operating parameters. In accordance with the present invention, this existing apparatus may thus be properly configured such that it is able to conduct configurations of operating parameters in the manner described above. In some embodiments of the present invention the ion source may use a plurality of electro-pneumatic elements and the ion source may be in ion communication with a RF-multipole ion guide and the electro-pneumatic superposition may be stepwise synchronized to the corresponding mass-to-charge ranges at which the RF-multipole ion guide is operating or at which the RF-mass filter is active. In some embodiments coordination/synchronization may involve stepping DC potentials on the electro-pneumatic elements. In some embodiments the synchronization may occur as a continuous function in contrast with step function synchronization. In some embodiments the ion source may use a plurality of electro-pneumatic elements and the ion source may be in ion communication with an ion trap, and the goal of the coordination/synchronization is to optimize electro-pneumatic superposition inside the ion source such that the mass-to-charge range at which the ion trap is trapping is maximally utilized. The coordination/synchronization may involve stepwise changing or continuous ramping of DC potentials on the electro-pneumatic elements. Charge Injection Overview Aspects of the present invention address a significant problem associated with conventional MALDI, in the rate of ion generation is highly inefficient; the presently described “Charge-Injection” LDI/MALDI (CIN-LDI/CIN-MALDI) ion source technology achieves orders-of-magnitude higher sample ionization efficiency over conventional systems by exposing the ejected neutral sample molecules to a controlled and directed beam of stable, low molecular weight ions originating from an ion beam gun. By way of understanding terminology and usage herein, “CIN” is an acronym referencing “charge injection”, and “CIN-ion gun”, “CIN-gun”, “CIN-ion source”, and “CIN-source” all refer to a device that generates low molecular weight ions, typically being a type of duo-plasmatron, radio-frequency (RF), micro-wave, or Penning type ion gun. This approach yields improvements in data sensitivity of up to one or more orders of magnitude from minute amounts of biological macromolecules, with sample amounts as small as the deep sub-atto (10−18) mole range. The described CIN-LDI/CIN-MALDI technology can also be used in conjunction with so called collisional (sample) ion cooling and electro-pneumatic superposition which can, in addition, reduce ion fragmentation, thereby addressing the second basic problem of conventional MALDI, that of molecular fragmentation and decay. Typically a UV laser (sometimes IR) is fired at the crystals in the MALDI spot with typical pulse duration on the order of tLP≈10−9 to 10−8 s. The matrix molecules in the spot absorb the electromagnetic laser energy and it is thought that primarily the matrix is ionized by this event. The matrix is then thought to transfer part of their charge to the analyte (e.g. a protein), thus ionizing them while still protecting them from the disruptive energy of the laser. Ions observed after this process are typically ionized by the addition of a proton to [M+H]+ or the removal of a proton [M−H]−. MALDI generally produces singly-charged ions, but multiply-charged ions such as [M+2H]2+ have been observed specifically in conjunction with IR lasers. However, a thorough analysis of the budget of ions in a mass spectrometer shows that the total ionization efficiency of MALDI is very low. FIG. 22 shows a simplified schematic overview of a typical ion budget in a current MALDI ion source 2201 connected to a triple-quad TOF mass spectrometer 2202. The sample 2203 is exposed to pulses of laser radiation 2204 which generates sample ions 2205 which are introduced into the mass spectrometer 2202. After (selectively) passing through the mass spectrometer 2202, the ions 2205 are eventually detected and converted in electrical signals by the ion detector 2206, and electronically counted by connected equipment. If, for example, in a conventional device as illustrated in FIG. 22, a sample of 1 pmol (6·1023·10−12=6·1011) of stable biological macromolecules with a mass on the order of m=103 u is introduced, an ion count on the order 104 can be expected at the detector 2206. It is known that the total ion transmission efficiency of that particular type of mass spectrometer (including detector efficiency, duty cycle, quadrupole transmission etc.) is on the order of 10−2. This means that approximately only 106 ions 2205 are transmitted from the MALDI ion source into the mass spectrometer. Since the sample contains 6·1011 molecules, the ionization efficiency is on the order of 106/6·1011≈1.6·10−6. Thus, approximately only one sample molecule per million becomes an ion and is transmitted into the mass spectrometer. The ionization efficiency depends also on the total sample amount as well as many other more or less difficult to control parameters such as the matrix crystallization process, the matrix chemistry, laser operating parameters etc. However, even if this approximation would underestimate the ionization efficiency by one order of magnitude it is still apparent that a fundamental shortcoming of state-of-the-art MALDI is the lack of ionization efficiency. Further improvements in mass spectrometer performance can be helpful but have by far less potential than improvements on the ion source and its ionization efficiency. The creation and transfer of free charges to sample molecules in a conventional MALDI process can in fact be considered a byproduct. Aspects of the present inventive CIN-LDI/CIN-MALDI system solve this problem by exposing the ejected neutral sample molecules to a controlled and directed low energy ion beam of stable, low molecular weight (CIN-beam) originating from an ion beam gun and causing a portion of the ions in the CIN-beam to collide-with and attach to the neutral sample molecules, thereby substantially increasing the total ionization efficiency. In conventional MALDI systems, the samples to be investigated are typically placed on chips with specially prepared surface chemistry in order to support the MALDI/SELDI process—MALDI chips. The samples spots on these chips are arranged either linearly in a single row (1D MALDI chip) or in an orthogonal array of spots (2D MALDI chips). Further, typically, the specific shapes and sizes of 1D and 2D MALDI chips differ between manufacturers. This manufacturer-specific constraints on chips poses yet another shortcoming of conventional systems, whereby a user may not easily mix and match prepared chips with different instruments, and thereby be disallowed from exploiting the technical advantages of various systems. Thus, embodiments of a larger inventive system of which the inventive LDI ion source is a part, may further include a self-adjusting holder and insertion system that is able to detect and adjust itself to the size, shape and type of inserted chip thereby freeing a user from having to use only one specific type of MALDI chips with a given LDI ion source. This aspect of the larger inventive system will be further described, in detail, in another application. Detailed View As noted above, the ionization efficiency of current LDI/MALDI ion sources is very low. A factor underlying this inefficiency, as the applicant has inventively recognized, is the lack of sufficient free charges and insufficient time and probability to transfer existing charges to created neutral sample molecules. In conventional MALDI ion sources, the available time for ionization is approximately only on the order of the duration of the laser pulse or slightly above (t≈101 ns). Thereafter, the plume expands and the few free charges in form of electrons and protons are rapidly extracted from the plume due their substantially lower mass-to-charge ratio m/q compared to sample ions of interest, with a typical m/q≈102 u/e to 105 u/e. Experimental results have shown that the velocities with which ions and neutrals are ejected from MALDI targets are on the order of ve=102 m/s to 103 m/s. (See e.g. Volker Bökelmann, Bernhard Spengler and Raimund Kaufmann: “Dynamical parameters of ion ejection and ion formation in matrix-assisted laser desorption/ionization”, Eur. Mass Spectrom. 1, 1995, page 81-93). With typical dimensions of MALDI ion sources being on the order of 10−2 m, the applicant has determined that a time interval of at least t=10−4 second to 10−5 for interaction in certain embodiments with the charge injection beam would be available. Therefore, the inventive CIN-LDI/CIN-MALDI system hugely increases ionization efficiencies by providing a directed high density of free charges (injected CIN-ions) in a manner that increases the collision probability between the CIN-ions and the desorbed sample neutrals. As shown in FIG. 23 depicting an embodiment of the invention, a CIN-beam 2302 of stable low molecular weight ions (such as H [protons], He, Li, O, Ne, Na, Ar, K, Xe, etc.) originates from a dedicated ion beam gun 2303 (typically a duo-plasmatron, RF, Micro-Wave, or Penning type) which is either an integral part of the CIN-LDI/CIN-MALDI ion source or attached to it in a separable configuration. The ion source is not drawn to scale, and is substantially larger than illustrated. The CIN-beam is directed onto the same sample 2203 spot to which the laser beam 2204 is directed. The sample is typically deposited onto a carrier or chip 2301. The neutrals of the sample 2304 which are desorbed by the pulsed laser beam 2204 expand into the hemisphere 2305 above the chip 2301. Realistically, the expansion is non-isotropic and depends on the angle with which the laser is impinging, hence the illustrative approximation as a hemisphere only serves as simplified explanation. The irradiated sample region is exposed to an electric field generated by a variable voltage source 2306, thereby providing potential U to the at least partially conductive carrier or chip 2301 and typically axisymmetric electrodes 2308 of appropriate shape enabling the extraction of sample ions 2205. If the carrier or chip 2301 is non conductive, an additional electrode behind the chip may be used to create the electric field. In most embodiments a plurality of electrodes and variable voltage sources will be used to create the required electric fields. These voltage sources may commonly reference to ground or be entirely or partially be stacked and floating on another potential, for example the potential present at the elements of a mass spectrometer into which the sample ions are injected. An advantage of using a dedicated ion beam gun, per certain embodiments of the present invention, is that it enables (1) the generation and control high space charge densities, (2) spatial and temporal control and guidance of charges/ions with electric and/or magnetic field, and (3) synchronization of the charge injection with the laser operation. Typical achievable CIN-ion beam currents vary over several orders of magnitude (for example, I=10−6 to 10−2 A) and depend on the actual gun design, the operating conditions and the ion type. High beam currents are generally desirable. For example, assuming an ejection velocity of ve=5·102 m/s and in a 1st order, assuming isotropic velocity distribution, and further requiring that the ejected neutrals shall not have traveled more than re=2.5·10−3 m away from the sample surface (approximating the dimension of a CIN-beam diameter of d=5·10−3 m) a time of ti=(2.5·10−3 m)/(5·102 m/s)=5·10−6 s is interaction time between the neutrals and the CIN-ions is available. The number of charges injected by a current of I=2·10−3 A in the hemispherical volume 2305 defined by radius re is approximately: n ≈ 1 / e · t i · I ≈ ( 1.6 · 10 - 19 ⁢ A ⁢ ⁢ s ) - 1 · 5 · 10 - 6 ⁢ s · 2 · 10 - 3 ⁢ A n ≈ 6 · 10 10 Assuming that 1 fmol (=6·1023−15=6·108) of analyte molecules were deposited in the sample and desorbed by the laser pulse predominately as neutrals, the number of available charges exceeds the number of neutrals by two orders of magnitude. Duo-plasmatron, RF, Micro-Wave, or Penning type ion guns suitable for the CIN-beam injection are commercially available (e.g. ‘Oxford Scientific’, SPECS, National Electrostatics Corp.) and may be easily modified to satisfy the requirements of this particular application. In certain embodiments, the optimal (kinetic) ion energy is relatively low, typically on the order of some Ek=100 to some 102 eV. Since the kinetic energies of many ion guns are higher, in some embodiments ion beam deceleration may be required by means of additional retarding potentials. An example of such modification, if required, is described in Popova, et al.: “Construction and performance of a low energy ion gun”, J. Vac. Sci. Technol. A21(2) March/April 2003, pp 401-403. In FIG. 24, an example of a more complex configuration of an embodiment of the CIN-LDI/CIN-MALDI ion source is shown that enables additional control of the CIN-beam in cases where such control can not be effected by the ion beam gun itself. The example shows two electrodes 2308 and 2401 for sample ion extraction. It also shows a plurality of electrodes 2402 connected to additional variable voltage sources 2403 which can be used to retard or accelerate, focus, modulate, or deflect the CIN-beam. In FIG. 25 an embodiment of the present invention is depicted wherein a relatively weak CIN-beam is guided not directly onto the sample, but rather into an 3D RF ion trap 2501 to accumulate large amounts of charge. The ion trap 2501 is connected to a plurality of variable DC and AC voltage supplies 2502. The CIN-ions are then released in bunches from the trap and accelerated into the LDI/MALDI region synchronized with the laser pulses by means of the before mentioned electrodes 2402. Again, in this depiction all potentials on electrodes are referenced to ground which will not be the case in all applications. The potentials voltage supplies may be stacked and/or commonly floating on a supplied potential. The CIN-beam may be continuous, pulsed, or arbitrarily time-dependent modulated, preferably in a manner which is synchronized to the LDI laser(s) pulse(s). In another embodiment of the invention, as illustrated in FIG. 26, the CIN-beam current ICI(t) is pulsed or modulated in a pulse-like arbitrarily time-dependent manner, and synchronized with the laser radiant flux ΦL(t). As mentioned, typical duration times for the laser flux may be on the order of tLP≈10−9 to 10−8 second. The charge injection (tCI) depends on the chosen velocity of the CIN-ions and a characteristic dimension of the plume region; typical values are on the order of tCI=10−6 to 10−4 second. In addition, the potentials on the sample and the sample ion extraction electrodes 2401 and 2308 in the CIN-LDI/CIN-MALDI ion source are synchronized. During the CIN ion injection the potentials on the sample and the electrodes, here referred to as Uex(t), are turned off, or floated, or changed such that the CIN-ion trajectories are preferable or at least not disturbed by the electric field normally created by the sample ion extraction electrodes during extraction. After the CIN-ion injection pulse is completed, the potentials Uex(t) return to values optimal for the sample ion extraction. The duration tex of the extraction is primarily dominated by the laser repetition rate frep, typically on the order of frep≈101 to 103 Hz, and to a lesser extent on an optional wait time tw. The sequence repeats the according to the laser repletion. In one basic operating mode of certain embodiments of the invention, the kinetic energy of the CIN-ions is sufficient to reach the sample target. As a result the CIN-ion—sample interaction predominately occurs on the sample surface or its immediate proximity where the plume of neutrals expands. In a second basic operating mode, depicted in FIG. 27, the kinetic energy of the CIN-ions insufficient to reach the sample target causing the CIN-beam 2302 to reverse direction; this increases the collision probability with neutrals thereby having most of the ionization of the neutral sample molecules occurring in a region adjacent to the sample. However, the total achievable space charge density is smaller in this embodiment. Another embodiment of the invention is shown in FIG. 28, wherein an additional magnetic field, orthogonal to the plane of the drawing, is generated in region 2801. (The depiction is rendered in an oversimplified manner, as magnetic field has no sharp boundaries). This embodiment allows better sample access for the CIN-beam and more desirable arrangements of the ion beam gun 2303 since the CIN-beam 2302 is deflected by the magnetic field. The magnetic field also influences the trajectories of the extracted sample ions, however significantly weaker. This configuration utilizes the effect that Lorenz forces in magnetic field depend linearly on the velocity of a charged particle. Since the mass if the CIN-ions is orders of magnitude lower than typical sample ion masses, their velocity and hence the Lorenz force acting on them is significantly larger for a given kinetic energy. As a result, the bending radius is smaller. FIG. 29 shows an embodiment of the inventive CIN-LDI/CIN-MALDI ion source, such as the configuration depicted in FIG. 25, which is connected to further ion-optical elements, in this particular case to a RF quadrupole, which can be operated as ion guide or as mass/charge filter. The CIN-LDI/CIN-MALDI ion source, here shown as a separate unit 2901 from the RF quadrupole, may be also connected to any other type of ion guide or trap. FIG. 30 shows the same configuration of the invention as seen in FIG. 29 with the addition of preferably axisymmetric gas flow 3001 for collisional cooling of sample ions. FIG. 31 depicts an embodiment of the inventive CIN-LDI/CIN-MALDI ion source connected to a high-end triple-quadrupole-Time-of-Flight (TOF) instrument. Optimized Control The subsequently described embodiments of an active feedback and control system for ion sources and applies to both LDI and ES technology in conjunction with electro-pneumatic superposition. The following patent applications of Hieke are related to the presently described embodiments of the invention, and are included by this reference: “Ion source with controlled superposition of electrostatic and gas flow fields” (WO05081944A2 and US2005194542A1, both filed on Feb. 22, 2005); and “Methods and apparatus for controlling ion current in an ion transmission device” (US2005194543A1 and WO05081916A2, both filed on Feb. 22, 2005). Provisional U.S. applications that are related and included by this reference are “Laser desorption ionization ion source with charge injection” (U.S. App. No. 60/798,377, filed on May 5, 2006) and “Laser desorption ionization ion source with self-adjusting holder and insertion system for one and two-dimensional sample chips” (U.S. App. No. 60/802,941, filed on May 23, 2006. As illustrated in FIG. 32 the functionality of advanced ion sources employing electro-pneumatic superposition, per aspects of this invention, depends on shape and arrangement of a number of so-called electro-pneumatic elements 3201. The sample ions originate from a small spatial area, typically a sample spot, 3202 and form a continuous or pulsed beam 3203 which is, in this example, injected in a RF multipole ion guide 3204. Gas flows through this structure as indicated by the arrows. To understand the operation of such ion sources, per aspects of this invention, the visualization of the electric fields and pneumatic flow fields created by the electric-pneumatic elements and the computation of ion trajectories are helpful. FIG. 33 shows one such example. The numerical solution of gas pressure (top) and gas flow velocity magnitude (bottom) for configuration depicted for the configuration shown in FIG. 32 at one particular operational point. Besides the gas pressure, the spatial distribution of the gas flow velocity magnitude 3301 is of particular interest. In practical applications, electro-pneumatic ion sources are contained in housings and connected to mass spectrometers. In some particular embodiments of the invention, as shown in the FIG. 34, the electro-pneumatic elements 3201 are supplied with gas via a reservoir 3402. The gas is supplied to the reservoir via one or more adjustable valves 3401. FIG. 34 also shows an ion source connected to a high-end triple-quadrupole time-of-flight (TOF) instrument that contains a series of RF multipoles 3204, a time-of-flight region 3403, including ion detector 3404. Mass spectra obtained with such configurations can exhibit many artifacts such as ion fragmentation, ion clustering, or insufficient ion transmission due to superposition breakdown if the ion source is not operating at optimal conditions. An example is shown in FIG. 35 that provides mass spectra obtained from a single labile compound at different reservoir pressures pmax of an electric-pneumatic LDI ion source. Since only a single compound is used the expected true signal is a single peak in the mass spectrum. Also indicated are the obtained intensities for the true peak 3501 at m≈2398μ. At pmax=25 Pa substantial ion fragmentation occurs which results in numerous peaks 3502 which do not represent the original composition of the sample. In addition, the total ion in intensity is a relatively low. At pmax=100 Pa the maximum ion count for the true peak has been reached, however, ion fragments are still observed. The highest signal to noise ratio is reached at pmax=200 Pa, although the total ion count is now reduced for this particular electro-pneumatic design. At pmax=300 Pa the signal to noise ratio decreases again due to the appearance of cluster ions 3503. In addition to varying the reservoir pressure the electric potential on the electric-pneumatic elements thereby the electric field inside the ion source has to be modified in order to maintain sufficient ion transmission. The actual optimal values for gas reservoir pressure and various electric potentials typically depend on the design of the electro-pneumatic elements, sample composition, surface chemistry of the chip as well as laser operation parameters in case of LDI. Further, it is apparent that the optimization can have different goals, such as improving the maximum ion count or the maximum signal to noise ratio. FIG. 36 illustrates an example, per embodiments of the invention, as to how variations in the gas supply may influence the spatial distribution of gas flow velocity magnitude 3301 and thereby the guidance of ions and the total available ion high-end count. On the left side, the numerical solutions of the gas flow velocity magnitude are shown, and on the right side, the resulting ion trajectories for two operational points. At the top of FIG. 36 an electric-pneumatic configuration is supplied from the surrounding gas reservoir (not shown) through three of the four existing channels. The fourth channel is used to evacuate the gas from the system. At the bottom of FIG. 36 the same electro-pneumatic configuration is used, however, gas is supplied only through two of the four channels and evacuated via the remaining two. The configuration on top shows more ion losses 3601. The aforementioned difficulties may be eliminated by implementing an active control and feedback system, per aspects of some embodiments, as shown in FIG. 37. The signal current from the ion detector is amplified 3701 and digitized 3702 to make the information contained in the mass spectrum processable by computer 3703. According to aspects of the present invention, this computer (or one communicating with it) can also measure various operational conditions of the ion source and actively control and set parameters. For example, the variable gas inlet valve 3705 may be driven, by a stepper motor or electromagnetically. The information required is provided to the valve controller by computer 3703. Various pressure values that are, as a result, established inside the ion source are measured by digital pressure gauges which, in turn, provide these values to computer 3703. In addition, computer 3703 can set potentials Φi on the electro-pneumatic elements 3201 via a plurality of digital to analog converters (DACs) 3707. Another embodiment is shown in FIG. 38 wherein (in addition to the active feedback system for electric-pneumatic components) a charge-injection ion gun creating a CIN-beam is used to increase the ionization efficiency of the LDI ion source as disclosed by above-referenced application of Hieke (U.S. App. No. 60/798,377, filed on May 5, 2006). The shown configuration will also require an additional magnetic field, orthogonal to the plane of the drawing. In some embodiments of the invention, the active control and feedback system may now also set values on the Charge-Injection gun to optimize total system performance. Radiation Supported Charge-Injection Liquid Spray FIG. 39 shows a liquid or liquid crystals containing sample molecules being introduced into a capillary 3901 or similar structure and dispersed as droplets 3902. A charge injection beam (“CIN-beam”) 3903 of stable low molecular weight ions (such as H [protons], He, Li, O, Ne, Na, Ar, K, Xe, etc.) originates form a dedicated charge injection ion beam gun 3904 is directed with specific, typically low energy (10−1 to 102 eV) and current onto a single or plurality of droplets 3902. The charge injection ion beam gun is either integral part of the RCIN-LS ion source or attached to it in a separable configuration. The CIN ions which are not absorbed in droplets may be collected by a grounded cup or a similar electrically conductive object 3906 at an arbitrary potential favorable to achieve desired CIN-ion beam trajectories. Also directed at a single or a plurality of droplets is a beam of electromagnetic radiation 3907 (EM beam), typically from a IR, UV, or visible Laser 3908. Radiation sources may further include any of known variants of solid state or gas phase lasers, OPO lasers, semiconductor lasers such as laser-diodes or arrays thereof, intense incandescent lamps, arc, glow discharges etc. Further possibilities include exposure to microwave or Terahertz electromagnetic radiation. The fundamental advantage of this configuration is that it allows to substantially increase the net charge state of the droplet(s) as well as their temperature/evaporation rate, effectively independent of an energy transfer with a optionally present background gas. Suitable ion beam guns for the CIN-beam injection (such as Duo-plasmatron, RF, Micro-Wave, or Penning type ion guns) may either be commercially available models (as provided, for example, by, Oxford Scientific, SPECS, or National Electrostatics Corp.) that may optionally easily be modified to satisfy certain specific requirements of this particular application or be integral part of the disclosed RCIN-LS ion source. The following references are relevant to this subject: M. R. Cleland and R. A. Kiesling: “Dynamag Ion Source with Open Cylindrical Extractor”, IEEE Transactions on Nuclear Science, June 1967; Stanley Humphries: “Charged Particle Beams”, Wiley-Interscience, April 1990, and Horst W. Loeb: “Plasma-based ion beam sources” 2005 Plasma Phys. Control. Fusion 47 B565-B576. The optimal (kinetic) ion energy is relatively low, typically on the order of Ek=10−1 to some 102 eV. Since the kinetic energies of many ion guns are higher, ion beam deceleration may be required by means of additional retarding potentials. An example of such modification is described in Popova, et al.: “Construction and performance of a low energy ion gun”, J. Vac. Sci. Technol. A21(2) March/April 2003, pp 401-403. The released ions 3909 are attracted by an electrode 3910 at appropriate electric potential. The electrode may further provide pressure decoupling between the two spaces on each side of it. The electrode may, for example, be followed by a RF multipole ion guide 3911 or any other ion trapping or analyzing configuration. Many of the depicted components are being held at electric potential by means of adjustable voltage sources 3912 such that favorable ion trajectories result. Various embodiments and aspects of the invention may vary from the depiction of FIG. 1. There may be differences in scale among embodiments, for example, either one of the beams (CIN and EM) may be larger or smaller in diameter than a typical droplet. There may further be a single or a plurality of CIN-beams, and there may be a single or a plurality of EM-beams. The process will typically occur at considerably less than atmospheric gas pressures to limit disturbance of the CIN beam. FIG. 40 shows a particular embodiment in which both CIN-ion current and laser photon flux may be arbitrarily modulated in time as well as spatially scanned and focused in one, two, or three dimensions. Additional voltage or current sources 4012 are connected to the CIN-ion gun to control beam current as well as to electrical or magnetic deflection systems 4001. The EM beam is deflected by a single or several pivoting mirrors 4002 which can be controlled in their position by electronic means such as signals from a pulse generator 4003 or, in general, driven by computer controlled DACs. The laser itself may be pulsed or continuous. Pulsed lasers may receive synchronizing signals from other, typically computer controlled, pulse generators. Further, the EM beam intensity may, in case of optical or near-optical wavelength, be modulated by means of Kerr cells or LCDs 4004 or similar devices which are also controlled by electronics means. Further still, the EM beam may be focused by an electronically controllable lens or lens system 4005. Additionally, a video camera, typically high-resolution high speed CCD, 4006 in conjunction with a microscopic optical arrangement 4007 may be used to observe droplets and also to derive control signals for the CIN and/or EM beam. FIG. 41 shows an embodiment wherein a relatively weak CIN-beam is guided not directly onto the droplet(s) but into a 3D RF ion trap 4101 to accumulate large amounts of charge. The ion trap 4101 is connected to a plurality of variable DC and AC voltage supplies 4112. The CIN-ions are then released in bunches from the trap and accelerated and guided onto the droplet(s). Again, in this depiction all potentials on electrodes are referenced to ground; this will not be the case in all applications. The potentials voltage supplies may be stacked and/or commonly floating on a supplied potential. The CIN-beam may be continuous, pulsed, or arbitrarily time-dependent modulated, preferably in a manner which is synchronized with the EM beam 3907. FIG. 42A shows an embodiment wherein additional electro-pneumatic elements 4201 are used to create spatially controlled gas flow velocity fields, gas pressure fields, and gas temperature fields as well as electric fields. The electro-pneumatic elements 4201 are held at electric potentials by means of additional voltage sources 4212. The superposition of said fields preferably supports droplet guidance, solvent evaporation, sample ion-solvent separation, ion guidance. Usually the fields will also influence the CIN-beam. Additional deflective means and/or modifications in the way the existing CIN-beam deflection system(s) are driven may be required to compensate such effects. The potentials on the electro-pneumatic elements 4201 may be any arbitrary function of time including pulsed and synchronized, including synchronized and delayed etc., with respect to any other operation of any other component such as the CIN-beam and/or the EM beam. Furthermore, by means of additional walls 4202 the interior may be divided into a number of domains 4203, 4204, and 4205 some of which may act as gas reservoirs. Said domains may be supplied with gas via typically electronically driven gas flow controllers 4220 or gas may be evacuated from them through openings 4221 of sufficiently low gas flow resistance. In the configuration shown in FIG. 42A, gas is supplied to domain 4203 which initially supports the guidance of droplets. Gas is also supplied to domain 4205 which (a) creates a counter flow with respect to the sample ions which supports removal of remaining neutrals and (b) creates a gas flow stagnation point in the center of domain 4204 which can be advantageous with respect to effecting charge injection and temperature control by means of the CIN-beam and EM-beam. Gas is evacuated from domain 4204 and 4206 through openings 4221. FIG. 42B shows an embodiment wherein only domain 4205 is supplied with gas and all other domains are evacuated. As a result, the gas flow is predominately counter to the droplet and sample ion motion. FIG. 42C shows an embodiment wherein only domain 4203 is supplied with gas and all other domains are evacuated. As a result, the gas flow is, at least on the axis of the system, predominately in the same direction as the droplet and sample ion motion. FIG. 43A shows an embodiment wherein the liquid containing the sample molecules is delivered to reservoir 4331. On the reservoir itself or in its proximity on the capillaries leading to and from the reservoir, electrically driven means 4330 to exert pressure on the liquid containing structure and thereby the liquid itself are mounted. Such means may be based on piezoelectric, electrostatic, electromagnetic, electro-optically and similar effects. Such an arrangement enables that single droplets or a plurality of droplets of predominantly specific size is/are formed and ejected with a specific velocity at times determined by the driving electric signal. Currently known designs of such droplet ejection mechanisms enable minimal droplet volumes on the order of 10−7 m3 to 10−8 m3 and ejection frequencies of several 104 Hz. In general small droplet volumes and high repetition rates are desirable although optimal values will depend on various conditions. The advantage of utilizing such mechanisms is that the droplet formation is largely independent of the pressure and rate with which the liquid is supplied, the degree of dissociation of the sample molecules, the electric conductivity of the liquid, and (specifically important) the electric field at the capillary tip from which the droplets are released. Specifically, the electric potentials on the droplet ejection mechanism/the capillary and the first electro-pneumatic element 4301 may be such that the electric field is small or zero in the space in between into which the droplets are initially injected. Optionally, and in addition to the CIN-beam and EM-beam exposure, the droplets may be exposed to very strong (pulsed) electric fields inside domain 4204, preferably in a manner synchronized/delayed to the CIN-beam and EM-beam exposure (since strong electric fields would influence the CIN-beam). FIGS. 42A-43A may not convey a particular feature of these embodiments of the electro-pneumatic system, which is that they are axisymmetric as far as is practical given other physical and design constraints. The symmetrically arranged arrows illustrating the gas may serve as a simplified illustration. To illustrate this concept FIG. 43B shows a 3D representation of the electro-pneumatic elements (3 quadrants are actually shown) including some droplets as well as the CIN-beam and the EM-beam. FIG. 44 shows the principle design wherein active control and feedback system analyzes obtained mass spectrometric data to derive signals that are sent to the ion source. A plurality of digital and/or analog inputs and outputs, such as, by way of example, variable voltage sources, ADC, DAC, computer controlled pulse generators, enable a main control computer to keep the ion source at optimal operational conditions. The parameters the computer can modify may include any one or more of (1) the potentials on the electro-pneumatic elements, (2) gas pressures and gas flow rates, (3) control potentials/currents for the CIN-gun and resulting CIN-beam energy, current, deflection, timing, and/or (4) control signals for the EM-beam including deflection, focus, intensity, timing. The computer may also utilize digitized video images of the droplets to control the CIN-beam and EM-beam. Ion Source with Controlled Liquid Injection FIG. 45 shows the principle configuration for a liquid based ionization techniques such as electrospray. A liquid containing sample molecules is introduced into a capillary 4501 or similar structure and dispersed as mist made up of a large number of droplets 4502. The droplets, and the sample ions 4503 which are eventually released from them, are moving towards an electrode 4504. Also shown, as an example, is a RF multipole-ion guide 4505 to which the ion source may provide ions. Some applications may also include means to effect additional gas flow, which can be helpful in separating neutrals from ions. In general, it is commonly difficult to actually achieve the formation of droplets, nebulization, and finally sample ionization, as this process depends on large number of parameters, including, for example, variables associated with sample concentration, degree of dissociation, liquid flow rate, liquid conductivity, liquid surface tension, capillary diameter, liquid pressure, electric field, gas flow fields, gas temperature fields, gas pressure fields. FIG. 46 shows a basic embodiment of the disclosed invention wherein the liquid or liquid crystal containing the sample molecules is delivered into a capillary or thin tube 4501 and said capillary extends into a reservoir 4602 relative proximity to the exit nozzle 4603 of the liquid. On the reservoir itself or the capillaries leading to and from the reservoir, typically electrically driven actuators 4601 to exert pressure on the liquid containing structure, and thereby the liquid itself, are mounted. Such mechanisms may be based on piezoelectric, electrostatic, electromagnetic, electro-optically and similar effects. Furthermore pressure wave inside the liquid may be utilized including reflection and/or scattering effects of such waves. Such an arrangement enables that single droplets or a plurality of droplets of predominantly specific size is/are formed and ejected with a specific velocity at times determined by the driving electric signal 4605 which is typically applied to the actuator(s) 4601 via amplifier(s) 4604. Somewhat comparable arrangements for dispensing liquid ink are commonly used today in inkjet printer heads. Currently known designs of such droplet ejection mechanisms enable minimal droplet volumes on the order of 10−7 m3 to 10−8 m3 and ejection frequencies of several 104 Hz. In general, small droplet volumes and high repetition rates are desirable although optimal values will depend on various conditions. The advantage of utilizing such mechanisms is that the droplet formation is largely independent of the pressure and rate with which the liquid is supplied, the degree of dissociation of the sample molecules, the electric conductivity of the liquid, and particularly, the electric field at tip of the exit nozzle 4603 from which the droplets are released. FIGS. 47A-D show several schematically-rendered examples of different configurations for the capillaries 4501, reservoirs 4602 and pressure actuators 4601. FIG. 48A shows a further embodiment in which from one reservoir a plurality of exit nozzles of different diameter is fed. This allows an ion source control system to vary the released droplet diameter (which will influence the ionization process) in order to optimize various aspects of the ion source performance such as, for example, total ion yield, spectral fidelity, or dominance of a certain preferred charge state. FIG. 48B shows a further variation of the embodiments shown in FIG. 48B wherein a plurality of reservoirs each feeds into a single exit nozzles of different diameter is fed. The fluid dynamic decoupling in such a configuration is stronger than in the one shown in FIG. 48B. Such a configuration allows an ion source control system to vary the released droplet diameter (which will influence the ionization process) in order to optimize various aspects of the ion source performance such as, for example, total ion yield, spectral fidelity, or dominance of a certain preferred charge state. Configuration 48A and 48B allow also the simultaneous release droplets of different sizes. Configuration 48B can also enable ejection of different liquid if additional feed-in capillaries 4501 are provided. A plurality of liquid ejection units may also be used to increase droplet ejection repetition rate by driving them in a time-staggered manner. Although the depictions in FIGS. 48A and 48B are simplified 2D renderings, the actual arraignment of the plurality of exit nozzles may assume various 3D shapes such as 1D linear, 2D linear, or concentric. FIG. 49 shows such an example where a plurality of liquid ejection units is arranged in an axisymmetric fashion. FIG. 50 shows an advanced embodiment wherein additional, typically axisymmetrical electrodes 5001 and 5002 are used, and which are held at certain electric potentials by additional voltage sources 5006. In one particular mode of operation, the electric potentials on the liquid ejection unit and the opposing electrode 5001 may be such that the electric field is small or zero in the space in which the droplets are initially injected but very high between electrode 5001 and 5002. In some modes of operation the value of the electric field may be sufficiently strong to extract ions from the droplets. In this depiction, again, all potentials on electrodes are referenced to ground; this will not be the case in all applications. The voltage supplies may be stacked and/or commonly floating on a supplied potential. FIG. 51A shows a configuration wherein the droplets are injected radially (not axially) into the high electric field region. In some modes of operation the value of the electric field may be sufficiently strong to extract ions from the droplets. The electric field is aligned such that those of desired polarity are then moving towards an ion-analytical instrument, here exemplified by the RF multipole. Ions of opposite polarity may be collected by means of a grounded cup or a similar electrically conductive object 5101 at an arbitrary potential favorable to achieve desired ion trajectories. FIG. 51B shows schematically a particular embodiment and mode of operation of the configuration shown in FIG. 51B. The potential which are applied to the electrodes are synchronized to the droplet injection such that a droplet is injected into a field free region and only when it reaches the axis of the system the appropriate potentials are applied. Such mode of operation may be achieved by utilizing a computer controlled system which utilizes a plurality of digital and/or analog inputs and outputs, such as, by way of example, computer controlled pulse generators, programmable delay units, variable voltage sources, ADC, DAC, etc. The actual duration of the pulse which initiates the droplet ejection and the time length during which the potentials in the electrodes are applied are in general not identical. Similar synchronization may also be applied in case of axial droplet injection. FIG. 52A shows an additional refinement by employing electrodes which are shaped and manufactured such that they at as electro-pneumatic elements 5201 which permits to establish spatially controlled gas flow velocity fields, gas pressure fields, and gas temperature fields as well as electric fields. The electro-pneumatic elements 5201 are held at electric potentials by means of before mentioned voltage sources. The superposition of said fields preferably supports droplet guidance, solvent evaporation, sample ion-solvent separation, ion guidance. The potentials on the electro-pneumatic elements 5201 may be any arbitrary function of time including pulsed and synchronized, including synchronized and delayed etc., with respect to any other operation of any other component such as droplet injection. Furthermore, by means of additional walls 5202 the interior may be divided into a number of domains 5203, 5204, and 5205 some of which may act as gas reservoirs. Said domains may be supplied with gas via typically electronically driven gas flow controllers 5220 or gas may be evacuated from them through openings 5221 of sufficiently low gas flow resistance. In the particular configuration shown in FIG. 52A, gas is supplied to domain 5204 and evacuated from domain 5203, 5204, and 5205 through openings 5221. This particular gas flow regime may serve only as an example, optimal gas flow configuration will depend on a number of design parameters and operational conditions. FIG. 52B shows a similar configuration except that droplet injection is axially-oriented, and the gas flow regime has been modified to such that gas is supplied to domain 5205 and also to domain 5203. This configuration creates (1) a counter flow with respect to the sample ions which supports removal of remaining neutrals and (2) a gas flow stagnation point in the center of domain 5204 which can be advantageous with respect to effecting charge separation on the droplets as well as to effect any additional physical operation on droplets such as controlled charge injection and/or temperature control e.g., by means additional beams directed at droplets. It should be understood that any feasible combination of such gas flows (direction) and droplet injections are included as embodiments of this invention. As a general comment on FIGS. 52A-54, it should be noted that although not apparent per se in the drawings, the entire electro-pneumatic system is generally constructed axisymmetrically, as far as practically possible. The symmetrically arranged arrows illustrating the gas may serve as a simplified illustration. FIG. 53 shows the configuration from FIG. 52A including an additional charge injection beam (“CIN-beam”) 5301 of stable low molecular weight ions (such as H [protons], He, Li, O, Ne, Na, Ar, K, Xe, etc.) which originates from a dedicated charge injection ion beam gun 5302 is directed with specific, typically low energy (10−1 to 102 eV) and specific current onto a single or plurality of droplets. The CIN-beam may be applied as a continuous beam or as a series of charge packets. Also directed at a single or a plurality of droplets is a beam of electromagnetic radiation 5303 (EM beam), typically from a IR, UV, or visible Laser 5304. Such a configuration allows a substantial increase in the net charge state of the droplet(s) as well as control of their temperature/evaporation rate, effectively independent of an energy transfer with any optionally present background gas. Various parameters of the CIN-beam (direction, focus, current, energy, timing) as well as EM-beam (flux, direction, focus, timing) can be electronically controlled. In a particular embodiment of such a configuration a plurality of digital and/or analog inputs and outputs, such as, by way of example, variable voltage sources, ADC, DAC, computer controlled pulse generators, programmable delay units, etc., enable a main control computer to control the ion source and to synchronize various operations with the droplet ejection. FIG. 54 shows a general design for embodiments of the invention wherein an active control and feedback system analyzes obtained mass spectrometric data to derive signals which are sent to the ion source based on controlled liquid ejection in combination with controlled superposition of electro-pneumatic fields. The control computer is equipped to control effectively all operational parameters of an ion source. The parameters the computer can modify may include any one or more of (1) the potentials on the electro-pneumatic elements, (2) gas pressures and gas flow rates, (3) control potentials/currents for the CIN-gun (if present) and resulting CIN-beam energy, current, deflection, timing, and/or (4) control signals for the EM-beam (if present), including deflection, focus, intensity, and/or timing. The computer may also utilize digitized video images of the droplets to control the CIN-beam and EM-beam. The goal of the optimization may be for example be any one or more of total ion yield, spectral fidelity, dominance of a certain charge state, or yield of a certain molecular mass. References, Claim Elements, and Equivalents of the Invention All patents, patent publications, and other published references mentioned herein are hereby incorporated by reference in their entireties as if each had been individually and specifically incorporated by reference herein. By their citation of various references in this document, applicants do not admit that any particular reference is “prior art” to their invention. An element in a claim is intended to invoke 35 U.S.C. §112 paragraph 6 if and only if it explicitly includes the phrase “means for,” “step for,” or “steps for.” The phrases “step of” and “steps of,” whether included in an element in a claim or in a preamble, are not intended to invoke 35 U.S.C. §112 paragraph 6. While particular embodiments of the invention and variations thereof have been described in detail, other modifications and methods of using the disclosed self-adjusting holder and insertion system for LDI will be apparent to those of skill in the art. Accordingly, it should be understood that various applications, modifications, and substitutions may be made of equivalents without departing from the spirit of the invention or the scope of the claims. Various terms have been used in the description to convey an understanding of the invention; it will be understood that the meaning of these various terms extends to common linguistic or grammatical variations or forms thereof. It will also be understood that when terminology referring, for example to physical equipment, hardware, or software has used trade names or common names, that these names are provided as contemporary examples, and the invention is not limited by such literal scope. Terminology that is introduced at a later date that may be reasonably understood as a derivative of a contemporary term or designating of a subset of objects embraced by a contemporary term will be understood as having been described by the now contemporary terminology. Further, it should be understood that the invention is not limited to the embodiments that have been set forth for purposes of exemplification, but is to be defined only by a fair reading of claims that will be appended to the non-provisional patent application, including the full range of equivalency to which each element thereof is entitled.
	abstract	System for separating and coupling a nuclear fuel assembly from/to a top nozzle which has a flow channel plate with guide holes. The system includes a lock insert and a separation member. The lock insert includes an insertion part provided on a top portion of a hollow body. The separation member is configured to separate the insertion part from a guide hole. The insertion part is variable in size. The insertion part comprises a first latching member and a second latching member, each having a step which contacts the flow channel plate. The first latching member includes a latching groove which is inserted into a member protruding from the top surface of the flow channel plate. The second latching member contacts a bottom surface of the flow channel plate. The separation member provides a space accommodating an outer circumferential surface of the first latching member.
	claims	1. A scattered radiation collimator for radiological radiation, comprising:a multiplicity of absorber elements connected one behind another in a collimation direction; andat least two plate holding elements, arranged substantially parallel with respect to one another and including absorber element holders for holding the absorber elements, the at least two plate holding elements being connected to each other by cross beams running along an end face with respect to each of the absorber elements. 2. The scattered radiation collimator as claimed in claim 1, wherein the absorber element holders include at least one of slits, recesses, depressions, and projections. 3. The scattered radiation collimator as claimed in claim 2, wherein the absorber elements include at least one of notches on an edge side and protruding lugs which engage into the absorber element holders. 4. The scattered radiation collimator as claimed in claim 2, wherein the absorber element holders include grooves or channels. 5. A radiation detector, comprising:at least one detection unit configured to detect radiological radiation; andthe scattered radiation collimator as claimed in claim 2, arranged upstream of the at least one detection unit. 6. A radiation detection device, comprising the radiation detector as claimed in claim 5. 7. The radiation detection device as claimed in claim 6, wherein the radiation detector is an X-ray computed tomography device. 8. The scattered radiation collimator as claimed in claim 1, wherein at least one cross beam is arranged on at least two opposite end faces. 9. The scattered radiation collimator as claimed in claim 8, wherein the at least one cross beam includes at least two cross beams, the at least two cross beams forming an integrally-formed cross brace. 10. The scattered radiation collimator as claimed in claim 8, wherein at least two crossing cross beams are, in each case, arranged on at least two opposite end faces. 11. The scattered radiation collimator as claimed in claim 1, wherein the cross beams run substantially diagonally on the end face. 12. The scattered radiation collimator as claimed in claim 1, wherein at least one of bolts, pins, screws and adhesive connect the cross beams and the at least two plate. 13. The scattered radiation collimator as claimed in claim 1, wherein the absorber elements are aligned confocally with respect to a focus. 14. A radiation detector, comprising:at least one detection unit configured to detect radiological radiation; andthe scattered radiation collimator as claimed in claim 1, arranged upstream of the at least one detection unit. 15. A radiation detection device, comprising the radiation detector as claimed in claim 14. 16. The radiation detection device as claimed in claim 15, wherein the radiation detector is an X-ray computed tomography device. 17. A scattered radiation collimator comprising:a multiplicity of absorber elements connected one behind another in a collimation direction; andat least two plate holding elements, arranged substantially parallel with respect to one another and including absorber element holders for holding the absorber elements, the at least two plate holding elements being connected to each other by cross beams running along an end face with respect to at least one of a longitudinal and transverse extent of the absorber elements, wherein the absorber elements include recesses corresponding to the profile of the cross beams on the end face, into which recesses the cross beams are at least partially lowered. 18. A scattered radiation collimator comprising:a multiplicity of absorber elements connected one behind another in a collimation direction; andat least two plate holding elements, arranged substantially parallel with respect to one another and including absorber element holders for holding the absorber elements, the at least two plate holding elements being connected to each other by cross beams running along an end face with respect to at least one of a longitudinal and transverse extent of the absorber elements, wherein the at least two plate holding elements and the cross beams are arranged and designed such that an attenuation of the radiation in a radiation transit direction, caused by the at least two plate holding elements and the cross beams, in a region of the cross beams, is approximately equal to an attenuation of the radiation in the radiation transit direction, caused by the holding elements only, in a cross-beam-free region. 19. A scattered radiation collimator comprising:a multiplicity of absorber elements connected one behind another in a collimation direction; andat least two plate holding elements, arranged substantially parallel with respect to one another and including absorber element holders for holding the absorber elements, the at least two plate holding elements being connected to each other by cross beams running along an end face with respect to at least one of a longitudinal and transverse extent of the absorber elements, wherein the absorber elements include recesses corresponding to the profile of the cross beams on the end face, into which recesses the cross beams are at least partially lowered, avoiding mechanical contact with the absorber elements.
	abstract	This invention teaches a method of performing gamma-ray microscopy and how to build a gamma-ray microscope. While the beam of gamma rays can not be manipulated like a beam of light or a beam of electrons, magnification is possible using a single-point source of gamma radiation. With this design, gamma rays originate from a tiny point in space and radiate outward as they travel away from the source. This results in magnification when a sample is placed between this single-point source and a detector array. The magnification factor is equal to the source-to-detector distance divided by the source-to-sample distance. A single-point source of gamma rays can be made by crossing a beam of positrons with a beam of electrons. The finer and more focused these beams are, the smaller the single-point source can be, and the higher the resolution can be. Methods of making and focusing electron beams are known in the art of making electron microscopy. These methods can be adapted to accelerate and focus positrons into a fine beam. Positrons can be harvested from radioactive isotopes that emit positrons and trapped by electric fields and magnetic fields for use when necessary. Mini versions of particle accelerator can trap positrons in an orbit for regulated or pulsed beam of positrons to be generated.
	summary
	summary
	claims	1. An electro-technical device, comprising:an input electrical connection supplied with an input signal and electrically isolated from an output electrical connection; anda bar magnet pivotally mounted on a pedicel between the input electrical connection and the output electrical connection; andat least one coil disposed adjacent to the bar magnet and being supplied with an electronic signal from a sensor, the bar magnet being responsive to an electromagnetic field generated by the at least one coil to cause the bar magnet to pivot to simultaneously come into contact with both the input electrical connection and the output electrical connection and complete a circuit and send out a control signal. 2. The electro-technical device according to claim 1, further comprising a housing for enclosing the bar magnet, the pedicel, the input electrical connection and the output electrical connection. 3. An electro-technical device, comprising:an input electrical connection supplied with an input signal and electrically isolated from an output electrical connection; anda bar magnet pivotally mounted on a pedicel between the input electrical connection and the output electrical connection; andat least one coil disposed adjacent to the bar magnet and being supplied with an electronic signal from a sensor, the bar magnet being responsive to an electromagnetic field generated by the at least one coil to cause the bar magnet to contact the input electrical connection and the output electrical connection and complete a circuit and send out a control signal, wherein the at least one coil includes a pair of coils including a first coil connected to one of a temperature sensor, a pressure sensor and a flow sensor and a second coil connected to a second one of a temperature sensor, a pressure sensor and a flow sensor. 4. A fault detection system for a nuclear reactor, comprising: a plurality of contactors each including;an input electrical connection supplied with an input signal and electrically isolated from an output electrical connection;a bar magnet pivotally mounted on a pedicel between the input electrical connection and the output electrical connection; anda pair of coils disposed on opposite sides of the bar magnet and each being supplied with an electronic signal from a sensor, the bar magnet being responsive to an electromagnetic filed generated by the pair of coils to cause the bar magnet to pivot to simultaneously come into contact with both the input electrical connection and the output electrical connection and complete a circuit and send out a control signal. 5. The fault detection system according to claim 4, wherein each of the plurality of contactors further comprising a housing for enclosing the bar magnet, the pedicel, the input electrical connection and the output electrical connection. 6. The fault detection system according to claim 4, wherein the pair of coils include a first coil connected to one of a temperature sensor, a pressure sensor and a flow sensor and a second coil connected to a second one of a temperature sensor, a pressure sensor and a flow sensor.
	claims	1. An X-ray anti-scatter device, comprising:an X-ray transparent dielectric material having a first lateral extent in a first direction, a second lateral extent in a second direction orthogonal to the first direction, the first and second directions defining a plane, the X-ray transparent dielectric material having a thickness orthogonal to the plane; anda set of X-ray opaque tubes extending at least partially through the X-ray transparent dielectric material, each of the X-ray opaque tubes having a selected axial orientation, a selected outside width and a selected inside width;wherein the X-ray opaque tubes comprise tungsten and the X-ray transparent dielectric material comprises at least one of borosilicate glass and anodic aluminum oxide. 2. The X-ray anti-scatter device of claim 1, wherein the thickness of the X-ray transparent dielectric material is substantially uniform across the first and second lateral extents. 3. The X-ray anti-scatter device of claim 2, wherein the set of X-ray opaque tubes extends substantially entirely through the plane. 4. The X-ray anti-scatter device of claim 2, wherein the set of X-ray opaque tubes have a cross sectional shape including at least one of circular, elliptical, oval, hexagonal and polygonal. 5. The X-ray anti-scatter device of claim 1, wherein the selected outside width and the selected inside width of each of the X-ray opaque tubes are selected to obtain an X-ray open area ratio of greater than 80%. 6. The X-ray anti-scatter device of claim 1, wherein the selected inside width of the X-ray opaque tubes and the thickness of the X-ray transparent dielectric material are selected to obtain a thickness to width ratio of greater than 100/1. 7. The X-ray anti-scatter device of claim 6, wherein the X-ray opaque tubes are straight and hollow. 8. The X-ray anti-scatter device of claim 1, wherein the tungsten comprises a conformal layer on an inside surface of a hollow capillary tube, and extends substantially an entire length of the hollow capillary tube. 9. The X-ray anti-scatter device of claim 1, wherein the selected axial orientation for each individual one of the set of X-ray opaque tubes is substantially directed towards a point a selected distance from the plane of the X-ray anti-scatter device. 10. A method of forming an X-ray anti-scatter device, comprising:forming a block from a set of parallel straight hollow capillary tubes, each hollow capillary tube comprising an X-ray transparent dielectric material having a selected inner diameter, a selected outer diameter, and a selected length;opening a first end and a second end of substantially each one of the set of parallel straight hollow capillary tubes; andforming an X-ray opaque material layer having a selected thickness on a surface of each one of the set of parallel straight hollow capillary tubes;wherein forming the X-ray opaque material includes depositing a first layer having a selected layer thickness formed by a set of thin layers of a first material;depositing a second layer having a selected layer thickness formed by a set of thin layers of a second material on the first layer; andalternately depositing additional layers of the first material and the second material, each individual first and second material layer having a separate selected thickness, to form the X-ray opaque layer having a selected X-ray opaque material layer thickness and a selected composition. 11. The method of claim 10, wherein the first material is comprised substantially of alumina and the second material is comprised substantially of tungsten. 12. The method of claim 10, further including selecting each first material and second material layer thickness to provide a specified X-ray opaque material composition for each of a set of thickness locations in the X-ray opaque layer. 13. The method of claim 10, wherein forming the layer of the X-ray opaque material includes atomic layer deposition. 14. The method of claim 10, wherein forming the layer of the X-ray opaque material includes forming a layer having composition selected for thermal stress relief with the X-ray transparent dielectric material. 15. The method of claim 10, wherein forming the block further includes at least some of the straight hollow capillary tubes having an elliptical cross section. 16. The method of claim 10, further including modifying the block to direct one end of each one of the straight hollow capillary tubes towards a point at a selected distance from a center point of the block. 17. The method of claim 16, wherein modifying the block further includes forming a substantially circular curve having a selected radius of curvature from the block having the set of parallel straight hollow capillary tubes. 18. The method of claim 16, wherein modifying the block includes at least one of thermal flowing the X-ray transparent dielectric material over a form, and cutting slices from the block. 19. A system for forming X-ray images, comprising:a source of X-rays;an X-ray anti-scatter device including a set of straight X-ray transparent hollow tubes, each tube including an X-ray opaque layer inside the hollow tube and a longitudinal axis directed at the source of the X-rays; andan X-ray detector attached to an X-ray imaging device;wherein the source of X-rays provides X-rays having a selected energy;and wherein the set of straight X-ray transparent hollow tubes comprise a borosilicate glass, and the X-ray opaque layer comprises a layer of tungsten having a thickness sufficient to block greater than 90% of X-rays from the source of X-rays. 20. The system of claim 19, wherein the X-ray imaging device comprises a scintillating material fixed adjacent to the X-ray anti-scatter device and a solid state imaging device fixed adjacent to the scintillating material. 21. The system of claim 19, wherein the X-ray anti-scatter device comprises a substantially flat plane having a substantially uniform thickness. 22. An X-ray anti-scatter device, comprising:a set of straight hollow open ended tubes formed of an X-ray transparent dielectric material, each straight hollow open ended tube including a layer of X-ray opaque material covering an inside surface;substantially all of the straight hollow open ended tubes aligned towards a selected point; andthe set of straight hollow open ended tubes physically connected to each other at one end of each tube to form a conic section curved surface;wherein the thickness of the X-ray opaque material is selected to obtain an X-ray open area ratio of greater than 80% and an X-ray stopping power greater than 90% for X-rays under a selected energy. 23. The X-ray anti-scatter device of claim 22, wherein each one of the set of straight hollow open ended tubes have a circular cross section. 24. The X-ray anti-scatter device of claim 22, wherein the X-ray transparent dielectric material comprises borosilicate glass and the X-ray opaque tubes comprises tungsten.
	claims	1. An electron beam sterilizer which sterilizes vessels being conveyed by irradiation with an electron beam, comprisingvessel holder means including a pair of holders which carries two vessels in vertical alignment, transfer means on which a plurality of vessel holder means are mounted at an equal spacing and cyclically transferred, inversion means for inverting the vessel holder means by rotating it about an axis parallel to a direction in which the transfer means advances, and an electron beam irradiator capable of irradiating the electron beam across the upper and the lower end of the two vessels which are carried in vertical alignment by the vessel holder means,the arrangement being such that a transfer path of the transfer means extends from a vessel feed position to a vessel discharge position and includes an inversion interval where the inversion means inverts the vessel holder means and an upright transfer interval where the vessels in vertical alignment are transferred in an upright position, the electron beam irradiator having an electron beam irradiation position which is chosen to be within the upright transfer interval, the vessels which are fed through the vessel feed position being discharged at the vessel discharge position after passing through the electron beam irradiation position and the inversion interval twice. 2. An electron beam sterilizer according to claim 1 in which the inversion means comprises a guide rail disposed along a transfer path for the vessel holder means, and an engaging member mounted on the vessel holder means and engaging the guide rail. 3. An electron beam sterilizer according to claim 1 in which the holder of the vessel holder means comprises a pair of holding plates which are attracted toward each other by springs, the holding plates being effective to hold a neck of a vessel sandwiched therebetween. 4. An electron beam sterilizer according to claim 1 in which the holder of the vessel holder means comprises a vacuum table which applies a vacuum suction for holding the vessel by sucking the bottom surface thereof. 5. An electron beam sterilizer according to claim 1 in which the electron beam irradiation position is chosen to be between a feed position where vessels are fed to the transfer means and a start position of the inversion interval. 6. An electron beam sterilizer according to claim 1 in which the electron beam irradiation position is chosen to be between an end position of the inversion interval and the discharge position where vessels are discharged from the transfer means.
	summary
052290662	description	DESCRIPTION OF THE PREFERRED EMBODIMENTS Inserting control rods into a nuclear reactor core causes a change in the axial and radial power distributions in the core. The changes in power distribution are correlated to changes in the signals from neutron or gamma ray detectors fixed in the core. The present invention utilizes measured deviations in fixed incore detector signals from established current reference values and correlates the deviations with rod axial positions to indicate rod position. The present invention provides an on-line, real time surveillance grade information system, as defined by IEEE or ANSI standards, for determining rod position and could, with suitable qualification, provide a protection grade, automatic reactor protection system. The present system first begins with a known fixed incore detector signal pattern produced when the control rods are in a current known reference position. From this known configuration a signature database is created by assuming movement of the control rods in the reactor in varying increments and configurations to create incore detector signal deviation patterns to be used for signature analysis. This can be accomplished by assuming movement of the rods into one of the possible positions in one of the possible configurations, determining the expected detector responses and storing, in a permanent memory, such as a magnetic disk, the expected changes or deviations in fixed incore detector signals which would be produced in that configuration. The system then assumes movement of the rods to a new position within that configuration and the expected or predicted changes in fixed incore detector signals with respect to reference signals are again stored. Once the predicted fixed incore detector signal deviations in all of the rod positions in the configuration are stored, the system performs the same operations on the next configuration and so forth until expected fixed incore neutron detector signal deviation patterns are stored for each position within each configuration. The distance or number of rod position steps between each assumed position is a fixed number of steps so that a database can be created which will facilitate searching for the exact rod positions. The signature database is updated periodically as the plant operates where periodically may mean once a day when the plant is in a base load mode and once every fifteen minutes during or following a load change. Once the signature database is created, when an anomaly is detected, such as when one or more incore detector responses deviate from the current reference responses or when a thermocouple response deviates from a current reference response, the signature database is scanned for a close match which, if it exists, indicates rod position. If a close match does not exist the closest configuration is used as a starting point for a search to find the exact rod position. This exact rod position is then compared to the rod position determined by the coil stack system or the thermocouple system. The system performs the deviation measurements within a reactor core 10, as illustrated in FIG. 1, where control rods 12 are inserted into the core 10 by a rod control system 14 to control power output. An analog rod position indication system 16 produces rod positions magnetically as previously discussed. These positions are provided to the rod position detection system 18 which correlates the rod positions with the signals produced by fixed incore detector strings 20 residing in the core. The detector strings can be conventional six segment detectors. The rod position detection system can also receive position signals from the enthalpy rise deviation rod position system described in U.S. Pat. No. 4,927,594 as an alternative or supplement to the positions provided by system 16. A computer system suitable for performing not only the functions of creating the database but also for performing the calculations to be discussed herein is available from the Commercial Nuclear Fuels Division of Westinghouse and is associated with the BEACON system. The present invention requires strings of fixed, incore thermal neutron or gamma ray sensitive detectors disposed in the reactor core so that at least one string of axially dispersed fixed incore detector sections is in the near vicinity of every control rod location in the core. It is also preferable that a detector string be located within a conventional King's move, as defined in chess, of each of the target control rods. With such a configuration, it is possible and practical to determine the degree of insertion of any individual control rod or any organized bank or configuration of control rods in the active region of the core by considering the pattern of output signals generated by the three dimensional array of fixed incore detectors in the reactor core. When the rods move in the core, the signals from the detectors within the core can be used to determine deviations from a previously stored current detector signal reference pattern for each axial section through the core as illustrated in FIGS. 2A and 2B. The deviation indicates an anomaly has occurred in the core. These figures illustrate four control rod locations 30-36 and five strings 38-46 of fixed incore neutron detectors. Each string includes typically six sections allowing the reactor to be divided into six different levels axially, however, depending on the core model used an alternate or different division of the core into axial regions is possible. FIGS. 2A and 2B illustrate typical contours of the deviations from the reference signal pattern which are detected by the detectors 38-46 of, for example, the first section or top most level and last or bottom most level. These figures illustrate control rods which are moved only partially into the core since a deviation pattern is shown in FIG. 2A and not in FIG. 2B. These deviation contour patterns would typically represent the levels associated with the highest and lowest detectors in a detector string with multiple detector sections. Typical deviation contour patterns allow the system to determine whether a rod has not been inserted into the level, that a rod has been inserted fully into the level, whether the rod has been inserted, for example, 30%, 50% and 70% into the level. The first step in performing the method of the present invention, as illustrated in FIG. 3, is to sample 70 the current core conditions which include not only the current rod positions used as a reference but also power level, inlet coolant temperature, etc. Once the current core conditions are sampled the system performs a routine calibration 71 of an analytical core analysis tool, such as the BEACON system available from the Commercial Nuclear Fuels Division of Westinghouse. Such an analytical core power distribution system has the capability, given input descriptions of certain system parameters such as reactor coolant system pressure and core inlet temperature, reactor power level and control rod insertion configuration and certain other core power distribution parameters, of calculating expected fixed incore neutron or gamma ray detector responses. The calibration step 71 involves the calculation of expected incore detector responses. If the calculated and measured responses do not agree within a predetermined degree of tolerance, the conventional control rod position indicator system is declared inoperable and the analysis tool must be adjusted. If adequate agreement exists both the measured and calculated responses are stored. Both the measured and calculated detector responses are stored because two measures of deviations need to be made, the first, the deviation of calculated detector responses from the calculated reference distribution and, the second, the deviation of measured detector responses from the measured distribution. Because the comparison is made in terms of deviations and not absolutes both reference distributions must be recorded. When the deviation database is constructed the calculated reference response distribution can be discarded. The system next initiates a loop or set of calculations to determine what the calculated deviations in response would be in predetermined control rod configurations. The predetermined configurations include changes in the rod positions that would be anticipated in normal operations, for example control bank D ten steps farther in or out. Also included in the configurations are anticipated changes in controlling and overlap bank positions, for example control bank D fifty steps in or out and one hundred steps in or out, if relevant, with control bank C maintaining a programmed overlap. Such configurations can occur as a result of a partial loss of load or other upset. Other predetermined configurations which can be anticipated from possible failure modes of the rod drive system are also included, such as a rod drop or uncontrolled insertion or withdrawal. For each of these configurations the deviation response of the core to the change or perturbation is determined. This step involves a search of configurations based on boron concentration or average coolant temperature to establish criticality in the calculations involving minor changes in control rod position and, for example, a search on power level to maintain critically in severely perturbed configurations. This search for expected configurations is necessary because, in a "major" upset event, such as an uncontrolled insertion or withdrawal of a rod group or, conversely, a partial loss of load without a reactor trip, the automatic control system will adjust primary systems conditions in an attempt to maintain criticality at a reduced power level or at zero power. Thus, if the control system thinks it has detected a partial loss of load it will run rods into reduce core power output. Therefore, the search should reflect predictable behavior of the automatic control systems, since such behavior is expected. If the automatic control system response is not what is expected, a reactor trip will occur and the issue of control rod position is moot--all rods are in. The predetermined configurations which should be used depend on the design of the core and rod control systems. A nuclear safety transient analysis engineer of skill in the art can develop a set of configurations for a particular reactor. For each configuration the system calculates 72 the difference or deviation between the detector signals of the calibration step and what the expected or calculated signals would be. That is, the system calculates expected deviations between the current, analytically expected responses and analytically anticipated responses. The calculation 72 of the expected detector response deviations is performed by the analytical core analysis tool. Once the expected detector response deviations are calculated the rod positions and expected response deviations are stored 74 in a signature database. If all the anticipatable rod configurations from the reference have not been determined 76, the assumed rod configuration is incremented 78 and another signature is calculated. If all configurations have been calculated, the system waits 80 until it is time for another periodic update. After the signature database is created the system enters a monitoring loop, as illustrated in FIG. 4, which looks for power distribution deviations from the observed reference. This loop is executed at least once a minute. In this loop the system samples 90 the fixed incore detector responses (or the thermocouples as an alternate) and then compares 92 the current responses to the reference responses stored in the calibration step. If the responses have not changed in an unexpected way the system waits 94 until it is time to perform another deviation detection operation. If the comparison of the current measured fixed incore detector responses with the stored measured fixed incore detector response indicates that the core power distribution has changed detectably, i.e. at least some fixed incore detector responses have changed by more than a predefined tolerance, such as 1%, depending on signal to noise ratios, etc. and acceptable Technical Specification limits, the system initiates a deviation signature analysis of the deviation signatures in the database created with respect to FIG. 3 to determine the rod configuration responsible for the observed change in the fixed incore detector responses. U.S. Pat. No. 4,637,910 describes one method of signature analysis that would be appropriate. During the signature analysis, in particular, when a change is detected, from the deviation the system can determine 96 the control rod or rod bank(s) that has moved and the direction of the movement. For example, the movement of a single rod alone (a rod drop) as compared to the movement of a bank alone will produce very different detector signal deviation patterns. The direction of insertion can be determined from the direction of the signal change. Generally, moving rods into the core lowers the magnitude of the response signal of the detectors in the vicinity of the rods while moving rods out increases the magnitude of the response signal in the vicinity of the rods. However, if the detectors are gamma sensitive and the control rods are silver-indium-cadmium or hafnium, the reverse is true. During the search the system selects 98 the closest signature to the current detector response deviations. This selection can be made by a simple deviation magnitude comparison. If the selected signature matches 100, the rod position is output 102. If a match does not occur, the rod configuration most nearly matching expected and observed deviations is a reliable indication of the change in the rod configuration that yielded the observed change in fixed incore detector responses. From this configuration the analysis tool (BEACON) is used to calculate a range of changes in position of the identified control rod bank or individual control rod in the appropriate direction. In each calculation the system computes the deviation of calculated response stored in the calibration step 71. In particular the system can start with the closest rod configuration and assume an incremental movement 102 from the closest rod position in the direction toward the actual detector responses. The increment for this search depends on the number of steps between the signatures, which, as previously discussed depends on the bank and whether banks are combined in the move. For example, if the movement is inward and the closest signature is farther inward (that is the expected responses in a certain axial region of the core are less than the actual responses), the system makes an incremental assumed rod movement further inward from the rod position of the reference. This incremental assumed rod position is used to calculate 104 expected detector response deviations. This calculation is performed by the analytical tool used for the calculations in FIG. 3 and uses the current core conditions for power level, inlet coolant temperature, etc. The deviations in expected responses are compared 106 with the observed deviations to determine if a match exists or is very closely approximated. If no match exists, the system determines whether the calculated expected response deviation is approaching 108 the actual response deviation, that is, whether the difference is decreasing. When the difference is no longer decreasing it means that the system has searched past the actual position and the latest assumed position is output 102. As an alternative to the incremental search discussed above an interpolation scheme can be used to determine the rod position change that yielded the change in fixed incore detector responses. The present invention has a unique advantage over the previous methods of determining control rod insertion since it addresses the primary consequence of control rod positioning, that of the effect on local power flux distribution, rather than that of secondary importance, absolute or relative control rod position. Thus, if the consequence of having one or more control rods inserted to a given degree is a local change in local nuclear power density, this local change will be evident to the nearby fixed incore detectors and to the system of this invention. If the consequence of having one or more control rods inserted to a given degree is of little concern, which would be the case if the rods are inserted in a low-worth region near the top of the core, the fixed incore detectors will be little concerned, even though current Technical Specifications, based on absolute error in rod positioning, could cause power reduction or, in the worst case, reactor shutdown. The present invention allows an unnecessary obstruction to efficient reactor operations to be avoided. The many features and advantages of the invention are apparent from the detailed specification and thus it is intended by the appended claims to cover all such features and advantages of the invention which fall within the true spirit and scope thereof. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation illustrated and described, and accordingly all suitable modifications and equivalents may be resorted to, falling within the scope of the invention.
	abstract	An apparatus and method of attenuating radiation includes oscillating at least one fluid having a radiation attenuating property between at least two chambers, incident to applied radiation. The radiation attenuating device includes at least two communicating adjacent chambers, at least one fluid having radiation attenuating properties moveable between the at least two chambers, and a control circuit configured to oscillate the at least one fluid between the chambers.
	summary
	summary
039473198	abstract	A nuclear reactor plant comprising at least two hydraulically separated but thermally interconnected heat conveying circuits, of which one is the reactor circuit filled with a non-water medium and the other one is the water-steam-circuit equipped with a steam generator, a feed water conduit controlled by a valve and a steam turbine, and a control system mainly influenced by the pressure drop caused in said feed water conduit and its control valve and having a value of at least 10 bars at full load.
046684689	claims	1. A fuel pellet for a nuclear fuel assembly fuel rod, comprising: a body having an inner portion disposed within an outer annular portion integral with and surrounding said inner portion, said inner portion being formed from compacted natural uranium oxide powder alone and said outer annular portion being formed of compacted mixtures of enriched uranium oxide and gadolinium oxide powders to provide a fuel pellet that has a lower reactivity than a conventional homogeneously mixed pellet at the beginning of life and a higher reactivity than a conventional homogenously mixed pellet at the end of life. a body having an inner part and an outer part integral with an surrounding said inner part, said inner part containing enriched nuclear fuel material and said outer part containing only natural nuclear fuel material to provide a fuel pellet that has a lower reactivity than a convnetional homogenously mixed fuel pellet at the beginning of life and a higher reactivity than a conventional homogenously mixed fuel pellet at the end of life. 2. A nuclear fuel pellet for a nuclear fuel assembly fuel rod, comprising:
	summary
	description	1. Field of the Invention The present invention relates to sanitizing systems, and more particularly, to a sanitizing apparatus for writing utensils. 2. Description of the Related Art Microorganisms are microscopic organisms that are too small to be seen by the human eye. Microorganisms can be bacteria, fungi, archaea or protists, but not viruses and prions, which are generally classified as non-living. Microorganisms are generally single-celled, or unicellular organisms; however, there are exceptions as some unicellular protists are visible to the average human, and some multicellular species are microscopic. Microorganisms live almost everywhere on earth, and certain microorganisms, such as pathogenic microbes, can invade other organisms and cause diseases that kill millions of people every year. In most commercial establishments, such as banks, there are writing instruments that are often used by the general public to sign documents and the like. These writing instruments, including pens, are a haven for dangerous microorganisms. Yet at the commercial establishments, the general public typically shares them, thus spreading the dangerous microorganisms from one person to another. There is a need to sanitize writing instruments to prevent the spread of dangerous microorganisms from one person to another. The present invention is a sanitizing apparatus for writing utensils. It comprises a housing assembly that has a top wall, a base, and first, second, third, and fourth walls. The first and second walls are perpendicularly disposed to the third and fourth walls. The third and fourth walls are lateral sidewalls that are in a parallel and spaced-apart relationship with respect to each other. The housing assembly also comprises an angled wall that is in between the third and fourth walls. The angled wall protrudes outwardly beyond the top wall a first predetermined distance and protrudes outwardly beyond the first wall a second predetermined distance. The angled wall terminates at the base and defines an elongated channeled slot through the top wall to receive at least one writing utensil. The second predetermined distance of the angled wall defines a tray that terminates with a lip, which prevents the writing utensils from falling off the tray. The housing assembly further comprises ultraviolet and ozone generating means for radiating the writing utensils within the housing assembly with rays and ozone. This effectively sterilizes bacteria and biological germs existing within the housing assembly and on the writing utensils. The housing further comprises electronic means to notify a user when the ultraviolet and ozone generating means is operating. The electronic means comprises at least one visual indicator that illuminates to notify the user when the bacteria and biological germs are being sterilized from the writing utensils. In the preferred embodiment, the housing assembly further comprises a battery compartment for a battery power source. In an alternate embodiment, the housing assembly comprises an electrical plug to connect to an electrical outlet. It is therefore one of the main objects of the present invention to provide a sanitizing apparatus for writing utensils to prevent the spreading of dangerous microorganisms from one person to another. It is another object of the present invention to provide a sanitizing apparatus for writing utensils with a source of ozone by means of an ultraviolet lamp, or other ozone generator, for sterilizing microorganisms. It is yet another object of this invention to provide such a device that is inexpensive to manufacture and maintain while retaining its effectiveness. Further objects of the invention will be brought out in the following part of the specification, wherein detailed description is for the purpose of fully disclosing the invention without placing limitations thereon. Referring now to the drawings, the sanitizing apparatus for writing utensils is generally referred to with numeral 10. It can be observed that it basically includes housing assembly 20, and ultraviolet and ozone generating assembly 60. As seen in FIGS. 1 and 2, housing assembly 20 comprises top wall 22, base 24 and walls 26, 28, 30 and 32. Walls 26 and 28 are perpendicularly disposed with respect to walls 30 and 32. Walls 30 and 32 are lateral sidewalls that are in a parallel and spaced-apart relationship with respect to each other. Housing assembly 20 also comprises angled wall 34, which is in between walls 30 and 32. Angled wall 34 protrudes outwardly beyond top wall 22 a first predetermined distance and protrudes outwardly beyond wall 26 a second predetermined distance. The second predetermined distance portion of angled wall 34 defines tray 40. Angled wall 34 terminates at base 24. Housing assembly 20 also comprises battery compartment 80 for a battery power source. Battery compartment 80 has door 82 that is accessible from base 24. As seen in FIG. 2, ultraviolet and ozone generating assembly 60 is housed within housing assembly 20. Ultraviolet and ozone generating assembly 60 radiates writing utensil U within housing assembly 20 with rays and ozone, to effectively sterilize bacteria and biological germs existing within housing assembly 20 and on writing utensil U. Ultraviolet and ozone generating assembly 60 comprises ultraviolet lamp 62 and ozone generator 64. Ultraviolet lamp 62 is known to neutralize bacteria and germs with ultraviolet rays, without detrimental side effects to the user. Ultraviolet rays produce a frequency that neutralizes bacteria and germs within housing assembly 20. Frequencies other than those known as ultraviolet can also be used if effective against bacteria and germs being suspected. As best seen in FIG. 2, ultraviolet lamp 62 and ozone generator 64 are mounted within housing assembly 20. Ozone generator 64 is affixed adjacent to ultraviolet lamp 62 and produces ozone to complement ultraviolet lamp 62. Electronic assembly 50 is also housed within housing assembly 20. Electronic assembly 50 notifies a user when ultraviolet and ozone generating assembly 60 is operating. Electronic assembly 50 comprises visual indicator 52 that illuminates to notify the user when bacteria and biological germs are being sterilized from writing utensil U. Visual indicator 52 is preferably located on top wall 22. In an alternate embodiment, instead of battery compartment 80, housing assembly 20 may comprise an electrical plug connected to electronic assembly 50 to connect to an electrical outlet. As seen in FIGS. 3 and 4, angled wall 34 defines elongated channeled slot 36 through top wall 22 to receive writing utensils U. It is noted that tray 40 terminates with lip 42, which prevents writing utensil U, or a plurality thereof, from falling off tray 40. Tray 40 has cutout 44 to facilitate a user in removing a sterilized writing utensil U from instant invention 10. Once the user has utilized writing utensil U, the user then inserts the used writing utensil U in through channeled slot 36 to be sterilized again. In the preferred embodiment, tray 40 alone and/or in combination with angled wall 34, contain a plurality of writing utensils U to effectively expose writing utensils U to ultraviolet lamp 62 and ozone generator 64. The foregoing description conveys the best understanding of the objectives and advantages of the present invention. Different embodiments may be made of the inventive concept of this invention. It is to be understood that all matter disclosed herein is to be interpreted merely as illustrative, and not in a limiting sense.
047626690	description	DETAILED DESCRIPTION OF THE INVENTION In the following description, like reference characters designate like or corresponding parts throughout the several views of the drawings. Also in the following description, it is to be understood that such terms as "forward", "rearward", "left", "right", "upwardly", "downwardly", and the like are words of convenience and are not to be construed as limiting terms. Referring now to the drawings, and particularly to FIGS. 1 and 2, there is shown a pressurized water nuclear reactor (PWR), being generally designated by the numeral 10. The PWR 10 includes a reactor pressure vessel 12 which houses a nuclear reactor core 14 composed of a plurality of elongated fuel assemblies 16. The relatively few fuel assemblies 16 shown in FIG. 1 is for purposes of simplicity only. In reality, as schematically illustrated in FIG. 2, the core 14 is composed of a great number of fuel assemblies 16. Spaced radially inwardly from the reactor vessel 12 is a generally cylindrical core barrel 18 and within the barrel 18 is a former and baffle system, hereinafter called a baffle structure 20, which permits transition from the cylindrical barrel 18 to a squared off periphery of the reactor core 14 formed by the plurality of fuel assemblies 16 being arrayed therein. The baffle structure 20 surrounds the fuel assemblies 16 of the reactor core 14. Typically, the baffle structure 20 is made of plates 22 joined together by bolts (not shown). The reactor core 14 and the baffle structure 20 are disposed between upper and lower core plates 24,26 which, in turn, are supported by the core barrel 18. The upper end of the reactor pressure vessel 12 is hermetically sealed by a removable closure head 28 upon which are mounted a plurality of control rod drive mechanisms 30. Again, for simplicity, only a few of the many control rod drive mechanism 30 are shown. Each drive mechanism 30 selectively positions a rod cluster control mechanism 32 above and within some of the fuel assemblies 16. A nuclear fission process carried out in the fuel assemblies 16 of the reactor core 14 produces heat which is removed during operation of the PWR 10 by circulating a coolant fluid, such as light water, through the core 14. More specifically, the coolant fluid is typically pumped into the reactor pressure vessel 12 through a plurality of inlet nozzles 34 (only one of which is shown in FIG. 1). The coolant fluid passes downward through an annular region 36 defined between the reactor vessel 12 and core barrel 18 (and a thermal shield 38 on the core barrel) until it reaches the bottom of the reactor vessel 12 where it turns 180 degrees prior to flowing up through the lower core plate 26 and then the reactor core 14. On flowing upward through the fuel assemblies 16 of the reactor core 14, the coolant fluid is heated to reactor operating temperatures by the transfer of heat energy from the fuel assemblies 16. The hot coolant fluid then exits the reactor vessel 12 through a plurality of outlet nozzles 40 (only one being shown in FIG. 1) extending through the core barrel 18. Thus, heat energy which the fuel assemblies 16 impart to the coolant fluid is carried off by the fluid from the pressure vessel 12. Due to the existence of holes (not shown) in the core barrel 18, coolant fluid is also present between the barrel 18 and baffle structure 20 and at a higher pressure than within the core 14. However, the baffle structure 20 together with the core barrel 18 do separate the coolant fluid from the fuel assemblies 16 as the fluid flows downwardly through the annular region 36 between the reactor vessel 12 and core barrel 18. As briefly mentioned above, the reactor core 14 is composed of a large number of elongated fuel assemblies 16. Turning to FIG. 3, each fuel assembly 16, being of the type used in the PWR 10, basically includes a lower end structure or bottom nozzle 42 which supports the assembly on the lower core plate 26 and a number of longitudinally extending guide tubes or thimbles 44 which project upwardly from the bottom nozzle 42. The assembly 16 further includes a plurality of regular transverse support grids 46 axially spaced along the lengths of the guide thimbles 44 and attached thereto. The grids 46 transversely space and support a plurality of elongated fuel rods 48 in an organized array thereof. Also, the assembly 16 has an instrumentation tube 50 located in the center thereof and an upper end structure or top nozzle 52 attached to the upper ends of the guide thimbles 44. With such arrangement of parts, the fuel assembly 16 forms an integral unit capable of being conveniently handled without damaging the assembly parts. Each fuel rod 48 of the fuel assembly 18 includes nuclear fuel pellets 54 and the opposite ends of the rod are closed by upper and lower end plugs 56,58 to hermetically seal the rod. Commonly, a plenum spring 60 is disposed between the upper end plug 56 and the pellets 54 to maintain the pellets in a tight, stacked relationship within the rod 48. The fuel pellets 54 composed of fissile material are responsible for creating the reactive power which generates heat in the core 14 of the PWR 10. As mentioned, the coolant fluid is pumped upwardly through each of the fuel assemblies 10 of the core 14 in order to extract heat generated therein for the production of useful work. To control the fission process, a number of control rods 62 of each rod cluster control mechanism 32 are reciprocally movable in the guide thimbles 44 located at predetermined positions in the fuel assembly 16. (Not all of the fuel assemblies 16 have rod cluster control mechanism 32 and thus control rods 62 associated therewith. In fact, only a small minority of the fuel assemblies do.) Specifically, each rod cluster control mechanism 32 is associated with the top nozzle 52 of the respective fuel assembly 16. The control mechanism 32 has an internally threaded cylindrical member 64 with a plurality of radially extending flukes or arms 66. Each arm 66 is interconnected to one or more control rods 62 such that the control mechanism 32 is operable to move the control rods 62 vertically in the guide thimbles 44 to thereby control the fission process in the fuel assembly 16, all in a well-known manner. All of the fuel assemblies 16 in the reactor core 14 have the conventional construction just described. However, an outer group of the fuel assemblies, each being designated as 16A and also identified by an "x" in the square boxes in FIG. 2, which are located along the periphery of the core 14 adjacent the baffle structure 20 also employ annular anti-vibration grids 68, a preferred embodiment of which is seen in FIGS. 3-6. The remainder of the fuel assemblies 16B in an inner group, which constitutes the vast majority of fuel assemblies in the core 14 and are positioned inwardly of and encompassed by the outer group of fuel assemblies, have no need for and thus do not employ the annular grids 68. As mentioned earlier, the baffle structure 20 which surrounds the fuel assemblies 16 of the reactor core 14 is made of plates 22 joined together by bolts (not shown). These bolts sometimes become loose thereby developing a small gap between the baffle structure plates 22. When this happens, a jetting action of the coolant fluid takes place through the baffle structure 20 in a radially inward direction from the exterior to the interior thereof due to the greater fluid pressure existing outside of the baffle structure 20 than within the core 14. In absence of the one or more of the annular anti-vibration grids 68 in the peripheral or outer group of fuel assemblies 16A in the core 14, the fluid jets impinging thereon would make their outer fuel rods 48 vibrate, eventually causing them to fail. Referring to FIGS. 4-6, the preferred embodiment of the annular anti-vibration grid 68 basically includes a plurality of interleaved inner and outer straps 70, 72 arranged and connected together, such as by welding, in an egg-crate configuration to define a plurality of hollow cells 74 open at their opposite ends and a large central generally square-shaped void region 76. Whereas each of the regular support grids 46, as conventionally known, defines a multiplicity of cells at least equal in number to the multiplicity or total number of the fuel rods 48 for receiving therethrough respective ones thereof and supporting them in a side-by-side array with respect to one another and to the guide thimbles 44, the plurality of cells 74 of the annular grid 68 is less in number than the multiplicity or total number of the fuel rods 48 in each fuel assembly 16A but are at least equal in number to a plurality of fuel rods positioned about the periphery of the multiplicity of fuel rods 48. Preferably, the cells 74 are equal in number to the number of fuel rods 48A in the outer three continuous rows in the square array of fuel rods. The cells 74 of the annular grid are sized to receive therethrough respective ones of the fuel rods 48A in the plurality thereof and engage the fuel rods so as to dampen any coolant fluid jetting or cross flow vibrations induced therein. On the other hand, the large central generally square-shaped void region 76 of the annular grid 68 is of a size adapted to receive therethrough the rest of the fuel rods 48 in the multiplicity thereof or those fuel rods 48B (which add up to a minority of the fuel rods) in the square array thereof bounded by the outer three continuous rows of fuel rods 48A. The preferred embodiment of the annular grid 68 seen in FIGS. 4-6 also includes means in the form of dimples or protrusions 78,80 defined on the respective inner and outer straps 70,72 which project from the planes of the respective straps into the cells 74 for engaging respective ones of the fuel rods 48A extending through the cells. Instead of protrusions 78 on the inner straps 70 forming a number of the cells 74, such number of the cells of the preferred annular grid 68 receive a like number of hollow cylindrical sleeves 82 therein. The sleeves 82 are attached, such as by welding, to the respective inner straps 70 and sized to receive a like number of the guide thimbles 44 therethrough for attachment of the annular grid 68 to those of the guide thimbles. The sleeves 82 can be attached to the like number of the guide thimbles 46 (for example, twelve thimbles in a 17.times.17 fuel assembly design) in a conventional way, such as by bulging or welding, such being the same manner that similiar sleeves (not shown) on the regular support grids 46 are attached to the guide thimbles 46. The alternative embodiment of the annular grid 68A seen in FIGS. 7-13 has the same protrustions 78, 80 and sleeves 82 as the preferred annular grid 68 and so reference should also be made to FIGS. 8-13 in the following discussion of the protrusions 78,80 and sleeves 82. The only difference between the preferred and alternative embodiments of the annular grids 68,68A is the inclusion of coolant flow deflecting means in the form of angular mixing vanes 84 formed on the inner and outer straps 78,80 which project upwardly and inwardly therfrom toward a central longitudinal axis of each cell 74. (The same reference numerals are used in referring to the components of the alternative annular grid 68A of FIGS. 7-13 as used to identify the components of the preferred annular grid 68 of FIGS. 4-6). The protrusions 78 on the inner straps 70 have a trapezoidal arched configuration open to normal longitudinal coolant flow through the annular grid 68 so as to minimize any effect on pressure drop through the grid, whereas the protrusions 80 on the outer straps 72 have a trapezoidal arched configuration parallel to normal longitudinal coolant flow through the annular grid 68 but across and in blocking relation to jetting flow from the baffle structure 20. Both of the protrusions 78,80 are generally rigid and formed on their associated straps 70,72 by a conventional stamping operation. Although protrusions 78 on the inner straps 70 project into the cells 74 a greater distance than protrusions 80 on the outer straps 72, both sets of protrusions 78,80 project into each of the cells 74 through a sufficient distance to contact and hold each fuel rod 48A received through each cell at four circumferentially spaced points on the respective opposing sides of the fuel rod. The relationship of the protrusions is such that two of them lie in a first horizontally extending plane, whereas the other two of the four protrusions lie in a second horizontally extending plane which is parallel to and axially spaced below the first horizontal plane. It can be seen from these views that each inner strap 70 has two protrusions 78 formed thereon at each cell 74, with one of the protrusions 78 projecting into one of the cells and the other projecting oppositely from the first and into the adjacent cell. It is important to note also that the sleeves 82, which attach the annular grid 68 to the several guide thimbles 44 being less in number than the total thereof in the fuel assembly 16A, are not connected with, and are substantially shorter in length than the distance between, the ones of the regular support grids 46 disposed above and below adjacent to the annular grid 68. A comparison of FIGS. 10 and 11 reveals that the sleeve 82 does not project by any substantial amount below the outer strap 72 of the grid 68. In such manner, the annular anti-vibration grids 68 being axially spaced along and connected to the selected ones of the guide thimbles 44 between at least some of the regular support grids 46 are entirely separate from and unconnected to the regular support grids. In instances where intermediate flow mixer grids, such as disclosed in the third application cross-referenced above, are already present between the regular support grids 46 in the top half of the fuel assemblies 16A, the annular grids 68 are only positioned between the support grids 46 being located nearer to the bottom nozzle 42 than to the top nozzle 44 or in the bottom half of the fuel assemblies, as is the case in FIG. 3. It will be understood that the fuel assemblies 16A with the annular anti-vibration grids 68 are only placed in the peripheral core locations most susceptible to coolant fluid jetting action through the baffle structure 20. Since the number of fuel assemblies with these annular grids 68 will be small, its impact on overall core pressure drop will be small. Also, since these peripheral core locations typically have low relative power, these assemblies will not become DNB limiting. The presence of the annular grid 68 in the outer three continuous rows of fuel rods 48A will cause more coolant to flow through longitudinally through the void region 76 of the grid and the center of the fuel assembly causing the grid to have an impact on DNB performance of the fuel assembly. But again, since the fuel assembly will have smaller relative power, the assembly will not become DNB limiting. Since the annular anti-vibration grids 68 are made of Zircaloy, and since only a few fuel assemblies will have these grids, the fuel cycle core penalty due to their presence will be small. Since it is preferable to limit the number of these fuel assemblies, they may be kept in the same peripheral core locations for several cycles. However, it is still advantageous to move these assemblies across the core diagonally in order to minimize burnup gradient and peaking factors. Unlike assemblies equipped with so-called anti-vibration clips, the assemblies with annular grids may be moved inboard to other low power locations if needed. From mechanical and handling viewpoints, the use of the annular grid is desirable since it is not necessary to remove this grid unlike the so-called anti-vibration clips. This eliminates need for special handling tools and the critical path for refueling is not impacted. It is thought that the invention and many of its attendant advantages will be understood from the foregoing description and it will be apparent that various changes may be made in the form, construction and arrangement thereof without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the form hereinbefore described being merely a preferred or exemplary embodiment thereof.
043022901	claims	1. A support structure system adapted for use in cooperative association with a nuclear reactor vessel comprising: a. mounting means operative for selectively mounting the support structure system in either one of a first and second positions relative to the nuclear reactor vessel; b. multiple deck means arranged in a tiered array, said multiple deck means being interconnected one with another to form an integral structure; c. a multiplicity of cables routed through said multiple deck means, said multiplicity of cables each having one end thereof extending in a first direction and having the other end thereof extending in a second direction oriented substantially perpendicular to said first direction; d. connector means operative for cooperatively associating said one end of each of said multiplicity of cables with the nuclear reactor vessel; e. first support means operative for purposes of providing a separation between individual ones of said multiplicity of cables, said first support means further being operative to provide support to said multiplicity of cables intermediate the length thereof; and f. a second support means operative for supporting said other end of each of said multiplicity of cables. 2. The support structure system as set forth in claim 1 wherein said mounting means includes a first mounting means operative for mounting the support structure system above and in spaced relation to the nuclear reactor vessel. 3. The support structure system as set forth in claim 2 wherein said mounting means further includes a second mounting means operative for mounting the support structure system in a laydown position relative to the nuclear reactor vessel. 4. The support structure system as set forth in claim 1 wherein each of said multiple deck means includes at least one floor-like surface lying in a substantially horizontal plane, and having openings formed therein for routing said multiplicity of cables therethrough. 5. The support structure system as set forth in claim 4 wherein said first support means comprises a multiplicity of channel-like cableways mounted in supported relation on each of said floor-like surfaces of said multiple deck means so as to occupy substantially the entire central portion thereof, said multiplicity of channel-like cableways being operative to receive therewithin said multiplicity of cables. 6. The support structure system as set forth in claim 5 wherein said second support means comprises a plurality of termination panels mounted on said floor-like surfaces adjacent the edges thereof and so as to extend substantially perpendicular thereto. 7. The support structure system as set forth in claim 1 wherein said connector means comprises a connector operative for connecting said one end of each of said multiplicity of cables to the nuclear reactor vessel. 8. The support structure system as set forth in claim 7 further including clamping means operative for clamping said multiplicity of cables in spaced relation to said one end thereof so as to permit said one end of said multiplicity of cables to move laterally in response to the existence of a seismic occurrence. 9. The support structure system as set forth in claim 1 wherein said multiple deck means are operative in the manner of a missile shield to absorb the kinetic energy of missiles striking thereagainst. 10. The support structure system as set forth in claim 1 wherein at least one of said multiple deck means is operative as a support for ductwork.
041644433	summary	BACKGROUND OF THE INVENTION This invention relates to nuclear reactors and in particular to an apparatus for holding down fuel assemblies within the reactor core. In pressurized water reactors the coolant flow rate and fuel assembly flow resistance are such that the hydraulic uplift force is of sufficient magnitude to cause the assemblies to jitter and even lift off the core support structure. Various approaches have been used to eliminate this detrimental movement. One suggested solution involves the use of a lock down device which attaches the lower end of the fuel assemblies to the core support structure. While this device will function properly it does introduce mechanical complexity since the device must not only lock and unlock remotely but it must release reliably after a year of operation in the reactor environment. Another approach has been to use springs located above each fuel assembly which bear against an upper alignment plate, thereby urging the fuel assemblies down. As reactors have been designed with increasingly large hydraulic uplift forces the spring force and the springs have become very large. Any component at this location limits the ability to obtain a desirable flow pattern and tends to increase the pressure drop of the coolant. In the design of nuclear reactors, a loss of coolant accident must be considered which involves a break of either the inlet or outlet line connected to the reactor vessel. In the event of a break of the outlet line the increased flow results in a substantial increase in the upward force on the fuel assemblies. A break of the inlet line on the other hand reverses the flow direction. Steam generated in the core remains behind as a steam pocket and forces the water backwardly through the core to the break at the inlet line. It would be desirable to maintain the water within the core while permitting the steam to escape through the break. SUMMARY OF THE INVENTION It is an object of the invention to hold down fuel assemblies in a simple manner which will eliminate or reduce the need for spring hold down forces and in a manner which will minimize flow restrictions due to the hold down structure. It is a further object to introduce these forces in a manner which will compensate for variations in the primary flow through the reactor with concomitant variations in upward force on the fuel assemblies. It is a further object to provide a steam release path through the reactor in the event of an inlet line break where the invention is used with the preferred embodiment. These and other objects are achieved in the invention wherein a nuclear reactor vessel is divided by a seal plate structure into a high pressure upper plenum and a low pressure plenum. A piston is in sealing and sliding relationship with the seal plate structure and it has push rods attached thereto which extend downwardly and hold down the fuel assemblies of the core. The piston in the preferred embodiment is located above the seal plate and seals against vertical extensions on the seal plate structure. The high pressure plenum is directly connection to the reactor vessel inlet and, therefore, the pressure above the piston approximates the inlet pressure. The lower surface of the piston is in direct fluid communication with the reactor vessel outlet and, therefore, the pressure below the piston approximates the reactor vessel outlet pressure. The pressure difference acting on the piston is a function of the pressure difference through the reactor and, therefore, the hold down force inherently compensates for differences in flow through the reactor. The substantial portion of the hold down structure is out of the primary fluid flow path since it is located at or above the seal plate structure. Only the tubular push rod which surrounds the control rod extends down toward the primary flow path. This push rod also forms a flow path for downward flow of coolant which is passing from the upper plenum downwardly to cool the control rods. The close seal between the piston and the seal plate structure is effected above the seal plate whereby adjustments may be made and installation effected prior to placing the core alignment barrel on the fuel assemblies. Assembly of the reactor is thereby simplified since the close fitting tolerances need not be handled during this operation. In the event of a loss of coolant accident due to a break of the outlet line, the inherent compensation characteristic of the invention increases the hold down force at the time that the high flow is tending to lift the assemblies. In the event of an inlet line loss of coolant accident, the reverse force on the piston causes the piston to disengage from the seal plate structure, thereby providing a flow path for the steam to pass to the broken inlet connection without passing downwardly through the core and forcing water out.
042808723	summary	The present invention relates to a core catcher associated with a fast nuclear reactor of the liquid-metal cooled type having a pressure vessel. This device is intended to collect reactorcore elements which are liable to melt either partially or completely as a result of a fast temperature rise caused by a major operational accident condition and then to fall under gravity to the bottom of the reactor pressure vessel which contains the liquid metal. A number of different designs of so-called core catchers or catchpots are already known. A device of this type generally consists of a structure of mechanically welded sheet metal plates mounted beneath a diagrid which supports fuel assemblies of the reactor core, the diagrid being in turn supported by a metallic structure which bears on the bottom wall of the pressure vessel. In a typical design, a core catcher is constituted by an array of cups or the like which are separated from each other and each capable of collecting part of the molten reactor core. The core catcher is so arranged that the liquid metal coolant contained within the reactor vessel is caused by an effect of convective heat transfer to circulate around the core catcher while producing a cooling action on this latter. As disclosed in particular in the U.S. Patent Application Ser. No. 589,881, now abandoned, filed on June 24, 1975, provision has already been made in a core catcher of this type for passages which extend through the diagrid support structure. Thus the cooled liquid metal collected within the pressure vessel at the outlet of heat exchangers of the reactor is circulated through said passages in order to produce a powerful cooling action on the core catcher while preventing any unacceptable temperature rise by removal of residual heat from the portions of molten reactor core which have thus been collected. This accordingly affords a satisfactory degree of protection of the other reactor structures contained in the pressure vessel. The present invention is concerned with another design concept of a core catcher in which the circulating liquid metal coolant is confined within an enclosed space, said core catcher being so arranged as to prevent any collected core debris from coming into contact with the pressure vessel. To this end, the device under consideration essentially comprises a collecting tray having a large area which is placed beneath the reactor core and pierced by a central chimney, and a bearing structure for said collecting tray extending in the form of a shell which is substantially parallel to the bottom wall of the pressure vessel, there being delimited between the bottom wall, the diagrid support structure and the diagrid an enclosed space which contains the collecting tray and in which a natural circulation of liquid metal can be induced under the action of the temperature differences arising from the fuel deposited on the collecting tray and by virtue of the presence of the chimney, said natural circulation being such as to ensure sufficient cooling of said fuel. During normal operation, the liquid metal contained in the enclosed space thus defined is practically stagnant except for leakages at the bottom end-fittings of the fuel assemblies through the diagrid and collected within said enclosed space, the leakage flow being intended to serve in a manner known per se to supply an annular region which is located between the pressure vessel and a parallel baffle wall and communicates with said enclosed space. In the event of a major accident which results in particular in partial or total melt-down of the reactor core, the core is collected on the tray within said enclosed space and produces an appreciable rise in temperature of the liquid metal in which said tray is immersed. A circulation of liquid metal is consequently established between the hot zone constituted by the collecting tray and the colder zones constituted by the walls which delimit said space, i.e. the walls forming the diagrid and the diagrid support structure and especially that surface of the diagrid support structure which is in contact externally with the mass of colder liquid metal contained in the pressure vessel. By virtue of these arrangements, the tray which serves to collect the debris from the molten reactor core can be placed beneath the core in the lowest portion of the enclosed space in such a manner as to ensure that said collecting tray has the largest possible area and extends in particular beyond the lateral limits of the reactor core. Preferably and in accordance with a particular feature of the invention, the collecting tray which is placed beneath the reactor core has a circular peripheral contour and a slightly conical shape from the periphery to the center in order to facilitate the circulation of liquid metal within the enclosed space. As an advantageous feature, the central chimney for the circulation of liquid metal is provided with an inclined top cover-plate carried by small columns, said cover-plate being intended to protect the pressure vessel against elements of the molten reactor core which fall onto the collecting tray. In accordance with a secondary feature, the collecting tray can have two walls separated if necessary by a clearance space. The top wall is advantageously formed by successive adjacent sheet metal elements provided with an overlapping zone from one element to the next. In accordance with a further distinctive feature, the collecting tray is supported on the bearing surface by means of a rigid structure constituted by vertical radial ribs which carry the collecting tray and are braced with respect to each other by means of circumferential stiffening members. The ribs are preferably provided with notches in order to reduce thermal stresses on those edges of said ribs which are in contact with the collecting tray and with openings for the circulation of liquid metal between said ribs. In accordance with yet another distinctive feature, the bearing surface which supports the collecting tray is suspended from the diagrid support structure by means of suspension members, that face of said bearing surface which is directed towards the pressure vessel being provided with shoes which are capable of coming into contact with said vessel in the event of failure of said suspension members.
048521426	abstract	An alloy filter in the form of a plate made from a homogeneous alloy comprising 85-95 wt. % cadmium, 5-15 wt. % copper and up to 3 wt. % of incidental impurities is interposed between a collimator and sodium iodide crystal of a gamma camera. The alloy filter improves image resolution by allowing the passage only of emmissions which impinge substantially perpendicularly on the collimator, while filtering out others which impinge obliquely.
055576508	abstract	A method for fabricating an anti-scatter x-ray grid for medical diagnostic radiography includes providing a substrate having channels therein and material that is substantially non-absorbent of x-radiation; and filling the channels with absorbing material that is substantially absorbent of x-radiation. In one embodiment, the step of providing a substrate having channels therein comprises sawing a plastic substrate with a thin circular blade and the step of filling the channels with absorbing material comprises melting the absorbing material and flowing the melted absorbing material into the channels.
	summary
	description	1. Field of the Invention The present invention relates to a biological-specimen observation apparatus. This application is based on Japanese Patent Application Nos. 2007-333870 and 2008-162127, the content of which is incorporated herein by reference. 2. Description of Related Art A known observation apparatus in the related art is capable of both observation of the distribution of a fluorescent material in a specimen and acquisition of clear, highly quantitative images of the fluorescent material by switching between an objective lens and an image-forming lens to achieve a broad range of magnification (for example, refer to Japanese Unexamined Patent Application, Publication No. 2005-316362). Furthermore, a known image acquisition apparatus in the related art displays the distribution of a fluorescent material in a specimen by obtaining and storing a bright field image and a luminous image and automatically generating an image in which the two images are superimposed (for example, refer to Japanese Translation of PCT International Application, Publication No. 2003-536052). Another known observation apparatus performs time-series contrast observation of a fluorescence image that contains an entire specimen (for example, refer to U.S. Pat. No. 5,650,135). However, the observation apparatus disclosed in Japanese Unexamined Patent Application, Publication No. 2005-316362 has a disadvantage of being unable to associate an image showing the distribution of a fluorescent material and a clear, highly quantitative image of the fluorescent material with each other. The image acquisition apparatuses disclosed in Japanese Translation of PCT International Application, Publication No. 2003-536052 and the observation apparatuses disclosed in U.S. Pat. No. 5,650,135 have a disadvantage of being unable to perform clear, highly quantitative fluorescence observation because they observe a specimen using a macroimage in which an entire specimen is acquired. The present invention is made in consideration of the above-described circumstances. Accordingly, it is an object of the present invention to provide a biological-specimen observation apparatus that allows observation of the distribution of a fluorescent material in a specimen and acquisition of the fluorescent material as clear, highly quantitative image data. To achieve the above object, the present invention provides the following solutions. According to an aspect of the present invention, a biological-specimen observation apparatus is provided which comprises a stage on which a specimen is mounted; a position detector, provided on the stage, that detects the position of the specimen; a light source that emits excitation light or illumination light onto the specimen mounted on the stage; an objective lens, disposed opposing the stage, that collects fluorescence or reflected light from the specimen; an image-forming lens that forms an image on the specimen, collected by the objective lens; an image acquisition unit that acquires the image on the specimen, formed by the image-forming lens; an image storage unit that stores the image obtained by the image acquisition unit and positional information of the specimen detected by the position detector in association with each other; and an image processing unit that performs combining processing of a plurality of the images stored by the image storage unit on the basis of the positional information stored in association with the images. In the above aspect, a diaphragm device capable of changing an aperture diameter may be provided between the objective lens and the image-forming lens. In the above aspect, there may be provided a focus detecting unit that detects focusing of the objective lens on the specimen; and an autofocusing unit that moves the stage in a direction along an optical axis of the objective lens on the basis of the detection result of the focus detecting unit so as to focus the objective lens on the specimen. In the above aspect, a zooming mechanism for changing zoom magnification may be provided between the objective lens and the image-forming lens; wherein the image storage unit may store the zoom magnification in association with the images and the positional information. In the above aspect, the image acquisition device may be a CCD camera, the observation apparatus having a function for changing an image acquisition region of the CCD camera and further comprising an information recording unit that records the obtained image acquisition region. In the above aspect, the image processing unit may have a function for trimming part of the stored images and combining processing them. In the above aspect, the image processing unit may have a deconvolution function. In the above aspect, the image processing may include at least the process of superimposing a bright field image and a fluorescence image. In the above aspect, the fluorescence image combined by the image processing unit may be subjected to image processing for changing the color in accordance with the brightness value. The present invention offers the advantages in that the distribution of a fluorescent material in a specimen can be observed and the fluorescent material can be obtained as clear, highly quantitative image data. Referring to FIGS. 1 to 4C, a biological-specimen observation apparatus 1 according to a first embodiment of the present invention will be described hereinbelow. As shown in FIG. 1, the biological-specimen observation apparatus 1 according to this embodiment is provided with an observation-apparatus main body 2, a control unit 21 that controls the observation apparatus, an operation storage unit 22 that provides a predetermined operation program to the control unit 21, an image control unit 3, and a display 4. The observation-apparatus main body 2 is provided with a stage 5 on which a specimen A, such as a small laboratory animal, for example, a mouse, is mounted, an observation optical system 6, and a case 7 that accommodates the observation optical system 6 to shield it from light. The observation optical system 6 is provided with a visible-light source 8 that emits visible light for bright-field observation, an excitation-light source 9 that emits excitation light for fluorescence observation, a light transfer member 10 that guides the visible light from the visible-light source 8 to the specimen A, a phototransmitting tube 11 that guides the excitation light from the excitation-light source 9 to the specimen A, a focusing mechanism 12 that adjusts the focal point of the specimen A, a zooming optical system 13 that adjusts the observation magnification, an objective lens 14 that emits the visible light and the excitation light onto the specimen A on the stage 5 and collects reflected light of the visible light returning from the specimen A and fluorescence, a diaphragm 15 that can change the beam diameter of the light collected by the objective lens 14, a dichroic unit 16 that separates the reflected light and the fluorescence collected by the objective lens 14 from the excitation light, an image-forming lens 17 that focuses the reflected light and the fluorescence collected by the objective lens 14 and separated by the dichroic unit 16 to form an image, and an image acquisition unit 18 that acquires an image of the specimen A formed by the image-forming lens 17. The stage 5 is an electrically driven stage, and the focusing mechanism 12 is an electrically driven focusing mechanism. The stage 5 and the focusing mechanism 12 can operate in response to signals from the control unit 21 and can also move to a desired position in response to signals from an external operating unit 20. The operating unit 20 is provided with a joystick for operating the stage 5 and a knob for operating the focusing mechanism 12. Furthermore, the stage 5 is provided with a position detector 19. Positional information detected by the position detector 19 is sent to an information recording section 3a. As shown in FIG. 2, an observation region is indicated on the upper surface 5a by an indicating line 5b in a color different from an upper surface 5a of the stage 5. Heat insulating unit is provided inside the indicating line 5b so as to keep the specimen A around 37° C. A holding mechanism for holding a mouthpiece for feeding anesthetic or oxygen to the specimen A is provided slightly inside the short side of the indicating line 5b. The case 7 has an opening 23 closed and opened by a door, for taking the specimen A in and out, in the vicinity of the specimen A. The dichroic unit 16 is provided with a dichroic mirror 16a that reflects excitation light and allows fluorescence and reflected light to pass through and band-pass filters 16b and 16c disposed on the excitation-light source 9 side and the image-forming lens 17 side, with the dichroic mirror 16a therebetween, to allow light of a specified wavelength to selectively pass through. The characteristics of the dichroic mirror 16a and the band-pass filters 16b and 16c are adjusted to match the wavelength characteristics of the fluorescent material to be observed. The dichroic unit 16 is disposed in such a manner that it can be inserted in and removed from an optical axis by means of a rotary turret mechanism, for example. A plurality of dichroic units 16 with different characteristics may be provided and may be freely inserted in or removed from the observation optical system 6. Furthermore, the excitation-light source 9 can be used as a visible-light source by setting the characteristics of the band-pass filters 16b and 16c on the excitation-light source 9 side to the entire visible band (for example, from 400 to 600 nm) and by using the dichroic mirror 16a as a half mirror. The control unit 21 is configured to control the focusing mechanism 12, the stage 5, the diaphragm 15, the zooming optical system 13, the insertion and removal of the dichroic unit 16, the image acquisition unit 18, the visible-light source 8, and the excitation-light source 9 of the observation-apparatus main body 2. All of them can be electrically controlled and can be operated in accordance with electrical signals from the control unit 21. The image control unit 3 is provided with the information recording section 3a that associates an image obtained by the image acquisition unit 18 with information from the observation-apparatus main body 2 and information from the position detector 19 of the stage 5, an image storage section 3b that stores the image associated with the information, and an image processing section 3c that processes the image. The operation of the biological-specimen observation apparatus 1 with this configuration according to this embodiment will be described with reference to FIGS. 3A and 3B. The specimen A is set on the stage 5 through the opening 23; the opening 23 is closed by closing the door; and the focusing mechanism 12 is operated to focus the specimen A irradiated by the visible-light source 8 while a live image obtained by the image acquisition unit 18 is being observed. In obtaining the live image, the obtained image passes through the information recording section 3a and the image storage section 3b and is displayed on the display 4 in real time. At that time, the diaphragm 15 limits the beam to a small diameter. After focusing, a program stored in the operation storage unit 22 is started so that a plurality of continuous adjacent bright field images is obtained. The images obtained by the image acquisition unit 18 are sent to the information recording section 3a and are stored in the image storage section 3b in association with the positional information of the stage 5 and the information of the observation-apparatus main body 2. After completing acquisition and recording of the plurality of images, the plurality of images are sent to the image processing section 3c and combined into one image on the basis of the positional information of the stage 5, stored in association with the images. The combined image is stored in the image storage unit 3b and is displayed on the display unit 4. Next, the visible-light source 8 is turned off, and the excitation-light source 9 is turned on to observe a fluorescence image. At that time, a desired dichroic unit 16 is used according to the characteristics of fluorescence to be observed. The diaphragm 15 is opened to the maximum. As in observation of bright field images, the fluorescence image is focused on while being observed by the image acquisition unit 18. After focusing, the operating unit 20 is operated to move the stage 5 so that the fluorescent material to be observed comes to the center of the field of view. Thereafter, the zooming optical system 13 is operated to set a desired magnification in accordance with the size of the fluorescent material. After the specimen A has been moved and the magnification has been set, focusing is performed again. After completing positioning, magnification setting, and focusing, a fluorescence image is obtained by the image acquisition unit 18. The image obtained by the image acquisition unit 18 is sent to the information recording section 3a and is stored in the image storage section 3b in association with the positional information of the stage 5 and the information of the observation-apparatus main body 2, and is then displayed on the display 4. Furthermore, the combining process of retrieving the plurality of images stored in the image storage section 3b and superposing them is performed by the image processing section 3c. When superposing the images in the image processing section 3c, the images are combined using positional information and magnification information stored in association with the images. The combined image is stored in the image storage section 3b and displayed on the display 4. A series of these operations is introduced by a wizard function in response to input of a start signal to the control unit 21 and is executed semiautomatically. The fluorescence image may be displayed in a rainbow, with the color changed according to the brightness value. Referring to FIGS. 4A, 4B and 4C, the flowchart in FIGS. 3A and 3B will be described in more detail. FIG. 4A is used to describe steps S1 to S11 of the flowchart in FIG. 3A. First, assuming that the size of the specimen A is 40×140 mm, the observation viewing region is 45×60 mm, and assuming that the image acquisition unit 18 is a ⅔-inch CCD camera, the projection magnification is about ×0.14. In step S1, an observer sets the specimen A using the indicating line 5b provided on the stage 5. “Turn on bright field setting” in step S2 indicates a state in which the visible-light source 8 is turned on and the dichroic unit 16 is removed from the observation optical system 6. “Turn off bright field setting” in step S11 is opposite thereto. In step S3, the diaphragm 15 is adjusted to reduce the beam diameter of an afocal optical system behind the objective lens 14 to about 10 mm (50%). In step S4, the observer performs focusing the operating unit 20. First, at N=1, the stage 5 is moved to the first position (step S5). Then, the position detector 19 of the stage 5 recognizes coordinates (0, 0). Image-acquisition is performed in this state (step S6), and the acquired image is associated with the coordinates (0, 0) of the upper left end. Furthermore, coordinates (0, 60) of the lower left end of the image, coordinates (45, 0) of the upper right end, and coordinates (45, 60) of the lower right end are associated by ascertaining the magnification information of the observation-apparatus main body 2 (step S7) In this way, the image with associated coordinates is stored in the image storage section 3b (step s8). Next, N is incremented to N=2, and the stage 5 is moved by a programmed moving amount X=0 mm and Y=60 mm to the second position (step S5). Then, the position detector 19 of the stage 5 recognizes coordinates (0, 60). Image-acquisition is performed in this state (step S6), and the acquired image is associated with the coordinates (0, 60) of the upper left end. Furthermore, coordinates (0, 120) of the lower left end of the image, coordinates (45, 60) of the upper right end, and coordinates (45, 120) of the lower right end are associated by ascertaining the magnification information of the observation-apparatus main body 2 (step S7). In this way, the image with associated coordinates is stored in the image storage section 3b (step S8). After this operation is repeated until N reaches N=6, six images from the first position to the sixth position shown in FIG. 4A are stored in the image storage section 3b. The six images from the first position to the sixth position are read from the image storage section 3b and are combined by the image processing section 3c in such a manner that the coordinates of the individual corners agree, to generate one combined image (step S9). The coordinates of the four corners of the combined image, that is, the coordinates (0, 0) of the upper left end, the coordinates (90, 0) of the upper right end, the coordinates (0, 180) of the lower left end, and the coordinates (90, 180) of the lower right end, are stored in the image storage section 3c in association with the image, and the image is displayed on the display 4 (step S10). Next, “turn off bright field setting” is executed (step S11), and the excitation-light source 9 is turned on to allow selection of the dichroic unit 16 (step S12). The observer sends a signal from the control unit 21 to select a desired dichroic unit 16 and dispose it in the observation optical system 6. Next, the diaphragm 15 is opened to an aperture diameter of about 20 mm (100%) in aperture diameter (step S13), and focusing is performed (step S14). The planar position of the specimen A is adjusted by the operator using the operating unit 20, and the zooming optical system 13 is operated in accordance with a signal from the control unit 21 so as to acquire a fluorescent material B at a desired position and in a desired size (step S15). Then, after focusing has been performed again (step S16), an image is obtained (step S17) and stored in association with the positional information of the four corners of the image on the basis of the positional information from the position detector 19 and the magnification information from the observation-apparatus main body 2 (steps S18 and S19). For example, as shown in FIG. 4B, in the case where the stage 5 is moved so that the upper left end of the observation region is set to (33.75, 75), and zooming is set at ×2, the upper left end of the image is stored as (45, 90). Here, the fluorescence-image acquisition processing from step S16 to S20 is performed by the observer a desired number of times (two or more times). Thereafter, the images stored in steps S10 and S19 are retrieved (step S20), and the fluorescence image stored in step S19 is superimposed on the bright field image combined in step S10 (step S21). At that time, the images are superimposed such that the coordinates stored in association with the image in step S10 and the coordinates stored in association with the image in step S19 are aligned. The image superimposed as shown in FIG. 4C is stored in the image storage section 3b and displayed on the display 4 (step S22). Thus, the biological-specimen observation apparatus 1 according to this embodiment can acquire an accurate bright field image and an image in which a clear fluorescence image is superimposed at an accurate position of the bright field image. This offers the advantage of allowing a fluorescent material in the specimen A to be clearly observed and the distribution of the fluorescent material in the specimen A to be quantitatively observed. Although this embodiment shows the stage 5 having the indicating line 5b for mounting one specimen A by way of example, a stage 105 having a plurality of indicating lines 5b to 5d for mounting two or more specimens A may be adopted, as shown in FIG. 5. The indicating lines 5b to 5d are arranged in the X direction at intervals of about 15 mm. In setting the specimens A, three specimens A are set in accordance with the indicating lines 5b to 5d. The program in the operation storage unit 22 is configured so that positions 1 to 18 are obtained as shown in FIG. 6. The other operations are the same as those of the flowchart in FIGS. 3A, 3B and 3C. This allows acquisition of an image in which a image of the fluorescence material that the observer desires is superimposed on a bright field image in which three specimens A are arranged side-by-side. This configuration offers the same advantages as the above-described embodiment and also the advantage of improving the throughput and allowing comparison among the specimens A by obtaining three specimens A at the same time. Although this embodiment adopts the dichroic unit 16 having the dichroic mirror 16a and the band-pass filters 16b and 16c, a combination with a tunable filter 401 may be adopted. As shown in FIG. 7A, the tunable filter 401 is disposed between a dichroic unit 402 that supports the dichroic mirror 16a and the band-pass filter 16b and the image-forming lens 17. The tunable filter 401 selects the transmission wavelength of fluorescence that is emitted from the specimen A and passes through the dichroic mirror 16a. The tunable filter 401 is a filter that can change the transmission wavelength in accordance with an electrical signal. The transmission wavelength changes in accordance with a signal from the control unit 21. In this case, the image processing section 3c needs an unmixing function for analyzing a partial wavelength characteristic of an obtained image to discriminate a fluorescent element. At the image-acquisition step S17 in FIG. 3, a plurality of images whose fluorescence wavelengths are shifted by the tunable filter 401 is obtained. Furthermore, in the superimposing step S21, the plurality of the fluorescence images is superimposed and subjected to unmixing so that a fluorescent element is discriminated. This allows acquisition of a clear image and discrimination of a fluorescent element. As shown in FIG. 7B, the tunable filter 401 may be disposed between the excitation-light source 9 and a dichroic unit 403. In this case, the dichroic unit 403 has the dichroic mirror 16a and the band-pass filter 16c. Changing the excitation wavelength using the tunable filter 401 allows wavelength analysis. With this configuration, the fluorescence transmission wavelength does not change, thus offering the advantage of causing no focus shift due to chromatic aberration of a fluorescence image. As shown in FIG. 7C, a half mirror 404 and tunable filters 401 disposed between the half mirror 404 and the excitation-light source 9 and between the half mirror 404 and the image-forming lens 17 may be disposed in place of the dichroic units 402 and 403. In this case, there is no need to provide a large number of dichroic mirrors 16a, offering the advantage of eliminating the need for insertion and removal thereof. As shown in FIG. 7D, in the case where a dichroic unit 405 having the dichroic mirror 16a in place of the half mirror 404 is disposed, the dichroic unit 405 may be detachably attached in accordance with the excitation wavelength and the fluorescence wavelength. This allows the excitation wavelength and the fluorescence wavelength to be selected freely, permitting acquisition of a fluorescence image suitable for a desired fluorescent dye. Referring to FIGS. 8, 9A, 9B and 9C, a biological-specimen observation apparatus 201 according to a second embodiment of the present invention will be described hereinbelow. In the description of this embodiment, components having a configuration common to the above-described biological-specimen observation apparatus 1 according to the first embodiment are given the same reference numerals, and descriptions thereof will be omitted. As shown in FIG. 8, the biological-specimen observation apparatus 201 according to this embodiment is not provided with the zooming optical system 13 but is provided with a plurality of switchable objective lenses 14 and 203 having different focal distances. These objective lenses 14 and 203 are held by a revolver 204 so as to be selectively inserted in and removed from the observation optical system 6. The objective lenses 14 and 203 have a viewing region as shown in FIGS. 9A, 9B and 9C. As shown in FIG. 9B, the objective lens 14 for observing the fluorescent material B in the specimen A has a viewing region smaller than that of the objective lens 203 and a high magnification. For example, its viewing region is 22.5 mm×30 mm and its magnification is about ×0.3. On the other hand, as shown in FIG. 9A, the objective lens 203 is capable of observing the entire specimen A and has a viewing region larger than the objective lens 14 and a low magnification. For example, its viewing region is 120 mm×180 mm and its magnification is about ×0.05. FIGS. 10A and 10B shows a flowchart of observation using the biological-specimen observation apparatus 201 according to this embodiment. In steps S1 to S10 for bright field observation, position adjustment and magnification selection are performed in new step S201 while a live image is being viewed. The position adjustment is performed using the operating unit 20, and the objective lens 203 having a wide viewing region and a low magnification is selected as an objective lens. This does not include the step S5 in which the movement of the stage 5 and image acquisition are repeated and the image combining step S9 in the first embodiment. Next, in steps S11 to S19 for fluorescence observation, switching between the objective lens 203 and 14 is performed in new step S202 by the operation of the revolver 204 instead of zooming during magnification selection. At that time, the objective lens 14 having a narrow viewing region and a high magnification is selected as an objective lens. As shown in FIG. 9C, this embodiment has the same advantages as the first embodiment, namely, an image in which a clear fluorescence image is superimposed at the exact position of a bright field image can be obtained and the distribution of a fluorescent material in the specimen A can be quantitatively observed, and also the advantage of simplifying acquisition of a bright field image to allow the acquisition of the image in a shorter time. Next, referring to FIG. 11, a biological-specimen observation apparatus 301 according to a third embodiment of the present invention will be described hereinbelow. Also in the description of this embodiment, components having a configuration common to the above-described biological-specimen observation apparatus 1 according to the first embodiment are given the same reference numerals, and descriptions thereof will be omitted. The biological-specimen observation apparatus 301 according to this embodiment is not provided with the focusing mechanism 12 for moving the stage 5 in the direction along the optical axis of the objective lens 14 but is provided with a linear motion mechanism 303 for moving the image-forming lens 17 in the direction along the optical axis. The linear motion mechanism 303 includes, for example, a linear motion guide having a motor serving as a driving source, a rail, and a slider, and a rack-and-pinion mechanism for transferring a driving force from the motor to the linear motion guide (not shown). The image-forming lens 17 is fixed to the slider, and the rail is fixed to an observation-apparatus main body 302. The linear motion guide is connected to the operating unit 20 so as to be operated also according to a signal from the operating unit 20. This mechanism allows focusing by moving the image-forming lens 17 in the direction along the optical axis of the objective lens 14. Thus, the biological-specimen observation apparatus 301 according to this embodiment has the same advantages as the biological-specimen observation apparatus 1 according to the first embodiment and also the advantage of reducing the problem of the changing image size during focusing to allow highly quantitative observation. Referring to FIG. 12, a biological-specimen observation apparatus 501 according to a fourth embodiment of the present invention will be described hereinbelow. Also in the description of this embodiment, components having a configuration common to the above-described biological-specimen observation apparatus 1 according to the first embodiment are given the same reference numerals, and descriptions thereof will be omitted. In the biological-specimen observation apparatus 501 according to this embodiment, it is possible to partially disable the functioning of an image acquisition device 502 of the image acquisition unit 18. If the diagonally shaded area in FIG. 13 is disabled, an image of the dotted-line area in the image acquisition device 502 is obtained. Furthermore, information on the disabled part is sent to the information recording section 3a together with the image, so that dotted-line area information is added to the obtained information. Positional information of the focusing mechanism 12 is passed to the information recording section 3a by a position detector 503. FIGS. 14A and 14B shows a flowchart of observation according to this embodiment. Although the steps from the specimen setting step S1 to the focusing step S4 and the stage-5-position moving step S5 (N=1) are the same as those in the first embodiment, a Z-position moving flow (step S401) is added thereafter. This is for obtaining several images with different Z-positions, which are used as reference images for the following projection processing (step S403). For example, assuming that this flow is configured to obtain images by vertically moving the stage 5 in two steps from the focal point and that the amount of movement is 1 mm, Z1=P+2 mm, Z2=P+1 mm, Z3=P, Z4=P -1 mm, and Z5=P -2 mm are obtained, where P is a focal point obtained in step S4. Subsequently, an image-acquisition-region setting step S402 for setting an area on the image acquisition device 502 to be disabled is provided between the Z-position moving step S401 and the image acquisition step S6. A limited acquired image is given information on the disabled area (acquired area) and Z-position information at the information recording section 3a and is stored in the image storage section 3b. A series of these observing operations is stored in the operation storage unit 22, so that the stage 5 and the image acquisition unit 18 are operated via the control unit 21 to allow image acquisition at the next position. After image acquisition up to the sixth position is finished, the image processing section 3c executes the projection processing step S403. Here, in-focus portions are extracted from the images at individual Z-positions according to their brightness value information and are combined into one image. Thus, the images at the individual positions become a clear image without defocus even if the specimen A has surface irregularities. After the projection processing step S403 is finished, the images are combined by matching the X and Y coordinate positions of the individual positions. This is set in the operation storage unit 22 so that the individual images are combined together without positional misalignment by using both the X and Y coordinates and the disabled area of the image acquisition device 502. Although the following fluorescence observation step until focusing, position, and magnification setting is the same as in the first embodiment, Z-position moving (step S401) is added before the image acquisition step S17, and thereafter, the projection processing step S403 is performed. Although the amount of movement of Z-position does not necessarily need to be the same as that during bright field observation, they are basically based on the same operating principles. The projection processing step S403 is the same as that during the process of bright field observation. The following steps of retrieving the bright field image in step S20, superimposing the bright field image and the fluorescence image together, and displaying the image are the same as in the first embodiment. This can correct an out-of-focus {a defocused} area of an image due to surface irregularities of the specimen A and provide a clear image in which the entire image is in focus without blurring around the viewing field. Because the area to be acquired is limited, the image acquisition time can be reduced. Although this embodiment excludes the periphery of the image by disabling the image acquisition device 502 of the CCD camera, the CCD camera may be configured to obtain an image as in the first embodiment and to trim the periphery of the image by postprocessing of the image. In this case, the moving coordinates of XY position need to be set in the operation storage unit 22 in consideration of the subsequent trimming process. Referring to a flowchart in FIGS. 15A and 15, a modification of the fourth embodiment will be described next. The apparatus configuration is the same as that in FIG. 12. In the flowchart of observation, instead of the projection processing step S403, a deconvolution processing step 501 is performed by the image processing section 3co The deconvolution processing allows the images at the plurality of Z positions to be reconstructed as a 3D image. The unknown spaces among the Z-positions are estimated from the brightness distribution of the images to form a 3D image. Likewise, also in fluorescence observation, the obtained images are subjected to deconvolution, and finally XYZ positional information of a fluorescent material in the specimen A and volumetric information of fluorescent material can be obtained.
	summary
043437613	summary	BACKGROUND OF THE INVENTION The present invention relates to a device for removing heat from a neutron-producing plasma. Heat energy is transferred from the plasma by means of neutron radiation and absorbed within a circulating solid media that is cooled for extracting heat energy for use. The neutron radiation is produced in a plasma containing ions of such as deuterium and tritium that react to produce helium and energetic neutrons. The plasma containing such reactions is fully described in U.S. Pat. No. 3,037,921 to Tuck, entitled "Method and Apparatus for Producing Neutrons and Other Radiations". This patent is expressly incorporated herein for the purpose of describing such a neutron-producing plasma. A neutron-producing plasma of this type can be produced not only by the reaction of tritium and deuterium to form helium ions and neutrons but also by various other reactions. For example, the reaction of deuterium with deuterium, helium isotopes with deuterium and helium with protons are contemplated. Reactions of these types also are suggested in the above patent as a source of neutron radiation. These neutron-producing reactions occur at extremely high temperatures and release very large quantities of energy. Previous coolant systems thus have been severely tested in regard to strength of materials and heat transfer rates due to the high temperatures and energetic output of these reactions. In addition, the problem of breeding additional fuel, particularly tritium, often is approached by combining this breeding function with that of heat transfer. One proposed system employs the gravity flow of solid lithium oxide microspheres for removing heat from the neutron-producing plasma as well as for breeding tritium through a neutron-lithium reaction. As is well known, both Li.sup.6 and Li.sup.7 react with neutrons to produce tritium and helium. However, the Li.sup.7 isotope has a greater propensity for reaction with energetic neutrons, which reaction additionally produces a secondary slow neutron. Other similar systems have proposed the use of molten lithium metal for this combined heat transfer and breeding function. The combination of heat removal and tritium breeding in a single media, although appealing from a functional and utilitarian viewpoint, has inherent and serious disadvantages. A major difficulty is that the heat transfer media becomes radioactive with the production of tritium which necessitates complicated and cumbersome maintenance techniques along with extended waiting periods for the decay of radioisotopes. The problem of tritium diffusion from the heat transfer system likewise must be considered. In addition, optimum breeding materials and conditions do not necessarily provide optimum characteristics for heat transfer such that a compromise as to desiderata in each of these functions may be required. Where lithium metal is selected its extremely high chemical reactivity and corrosiveness requires that it be kept scrupulously free of materials such as oxygen and nitrogen with which it reacts. PRIOR ART STATEMENT The following publications relate to but do not disclose the invention as claimed in the present application for patent. Miller et al., U.S. Pat. No. 3,976,888 discloses a device for reacting deuterium and tritium to produce 14 Mev neutrons and helium. The device is nested within the flux trap of a nuclear reactor and is cooled by a flow of deuterium-tritium gas. Goldstein et al., U.S. Pat. No. 3,899,676, discloses as in-core measuring device for power distribution and fuel breeding rates within a nuclear reactor. Beryllia balls containing uranium isotopes are fed into spindles located at desired positions within the reactor core and maintained there for a required period of irradiation. Subsequently the balls are driven from the spindles by sodium flow for radiation measurements. Winsche et al., U.S. Pat. No. 3,969,631, discloses a tritium breeding system in which lithium alloy targets are neutron-irradiated within gas coolant tubes. The product tritium is removed by the gas flow. Maniscalco and Meier, "Liquid-Lithium `Waterfall` Inertial Confinement Fusion Reactor Concept", Transactions of the American Nuclear Society, Vol. 26, page 62, June 1977. This report discloses a liquid-lithium waterfall which serves as a primary coolant, neutron moderator and fertile material for tritium breeding. Sze et al., "Gravity Circulated Solid Blanket Design for a Tokamak Fusion Reactor", Proc. at 2nd ANS Topical Meeting on Technology of Controlled Nuclear Fusion, 1976. This report discloses a falling bed of LiO.sub.2 microspheres for cooling and for breeding tritium in combination with a deuterium-tritium reactor. SUMMARY OF THE INVENTION Therefore, in view of the above, it is an object of the present invention to provide a system for removing energy from a neutron-producing plasma. It is also an object to provide a heat transport system for use with a neutron-producing plasma that is separate from the fuel breeding function. It is likewise an object to provide a heat transport system in which the heat transport media is a high-temperature, chemically inert material that does not activate to form long-lived radioisotopes and can be directly contacted by a secondary coolant fluid. It is also an object to provide a heat transport system in which the coolant media temperatures in regions near to the plasma are moderated in nearer accord with temperatures in regions away from the plasma. It is a further object to provide a heat transport system for use with a neutron-producing plasma in which containment walls between the plasma and media can be maintained at lower temperatures than that of the heat transport media. In accordance with the present invention, a heat transport system is disclosed for removing heat from a neutron-producing plasma. The system includes a vertical duct with its inlet above its outlet for passing a gravity flow of ceramic particles through its central region exposed to neutron radiation and thus energy transfer from the plasma. The ceramic particles are selected from alumina, magnesia, silica or a combination of these materials. A heat exchange vessel communicates with the outlet of the vertical duct and includes openings for passing a flow of coolant gas into direct heat exchange contact with the ceramic particles. The heated gas passes through circulatory means for maintaining its flow and for extracting heat energy for use. A conveyor is connected to the lower portion of the heat exchange vessel for upwardly transporting the ceramic particles to the inlet of the vertical duct and permitting the particles to gravitate through the central portion of the duct to the heat exchange vessel. In a more specific aspect of the invention, containers with lithium atoms in combined or elemental form are placed between the central region of the vertical chute and the neutron-producing plasma for breeding and recovering tritium by the reaction of lithium and neutron irradiation. In another important aspect, a lower portion of the vertical chute is constricted in open cross-sectional area to limit downward flow of particles and create a downwardly moving, packed bed. The duct and constriction are advantageously partitioned to provide a compartment, near to the neutron-producing plasma, which has a lower portion with a larger opening for discharge flow than the opening within the lower portion of a corresponding compartment disposed away from the neutron-producing plasma. This permits a greater linear flow of particles through the compartment near to the plasma and a lower maximum temperature than that of a falling bed that does not include this velocity partitioning. In another aspect of the invention, the ceramic particles are substantially free of material other than alumina, magnesia and silica. The particles are also generally globular in shape with a diameter of about 0.5 to 1.5 cm to facilitate solid flow within the bed. The invention also contemplates a method of removing energy from a neutron-producing plasma by passing a gravity flow of ceramic particles selected from magnesia, alumina, silica and combinations thereof through the neutron flux produced by the plasma to absorb energy and increase the particle temperature. The particles then flow outside the neutron flux to directly contact a coolant fluid which is subsequently employed as a source of heat energy. The cooled particles are recycled to again pass through the neutron flux.
	description	This application claims the benefit of Korean Patent Application No. 10-2016-0096128, filed on Jul. 28, 2016, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. One or more embodiments relate to an externally integrated steam generator type small modular reactor for a nuclear power plant, and more particularly, to an externally integrated steam generator type small modular reactor in which a steam generator is arranged along the circumference of a reactor vessel and a steam drum is arranged along the circumference of the steam generator in order to increase the heat transfer area of the steam generator, simplify the structure of the small modular reactor, and increase the spatial efficiency of the small modular reactor. In general, a reactor coolant system of a large pressurized-water reactor nuclear power plant includes a nuclear reactor, steam generators, reactor coolant pumps, and pipes connecting the components. The reactor coolant system may have a loop structure in which two to four steam generators are arranged around the nuclear reactor, one or two reactor coolant pumps are arranged for each of the steam generators, and pipes are welded to nozzles of the components. The steam generators include heat transfer U-tubes, evaporators, moisture separators, and steam dryers. In such a reactor coolant system of a large pressurized-water reactor nuclear power plant, pipes for connecting components to a nuclear reactor, steam generators, and reactor coolant pumps are individually installed. However, it is difficult to repair and maintain the pipes installed as described above, and basically, accidents such as leakage of a coolant may occur because of pipe break. That is, large nuclear power plants have to be designed by assuming break at both ends of pipes exposed to high pressure and high temperature and considering factors such as dynamic loads and pressure surges caused by break at both ends of pipes and are required to satisfy complex design specifications including environment verification so as to maintain integrity and functional stability in radioactivity and steam conditions in case of coolant leakage. Meanwhile, small-medium modular reactors are designed to have an integrated structure in which steam generators and reactor coolant pumps are integrated in a nuclear vessel for removal of connection pipes and pipe welding. FIG. 1 illustrates a small-medium modular reactor of the related art including a steam generator 20 provided in a reactor vessel 10. Referring to FIG. 1, the small-medium modular reactor of the related art includes the reactor vessel 10, the steam generator 20 provided in the reactor vessel 10, a core 30, turbines 40, and motor pumps 50. Since the steam generator 20 is installed in the reactor vessel 10, pipes may not be used in the small-medium modular reactor of the related art. However, the small-medium modular reactor of the related art may have the following problems. In the small-medium modular reactor of the related art, a complex structure is used to maintain a pressure boundary between secondary cooling water used in the steam generator 20 provided in the reactor vessel 10 and primary cooling water used for circulating heat generated in the core 30. That is, in the small-medium modular reactor in which the steam generator 20 is provided in the reactor vessel 10, a pressure boundary between primary cooling water and secondary cooling water is scattered in the reactor vessel 10, and thus a complex structure is used to maintain the pressure boundary. Furthermore, since the steam generator 20 is provided in the reactor vessel 10 of the small-medium modular reactor of the related art, the small-medium modular reactor has a limited degree of spatial efficiency and a complex structure. For example, since additional structures (such as the turbines 40) are arranged in the reactor vessel 10 to form paths for coolant pumps, the structure of the small-medium modular reactor is complicated. If the structure of the small-medium modular reactor is complicated as described above, access to the small-medium modular reactor is limited, thereby making it difficult to perform in-service inspection, repair, and maintenance and causing problems such as limited workability and an increase in the use of anti-radiation suits. Therefore, the operability and stability of the small-medium modular reactor may decrease. Furthermore, in the small-medium modular reactor in which the steam generator 20 is provided in the reactor vessel 10, moisture separators and steam dryers may not be installed in the steam generator 20 but may have to be installed in separate components outside the steam generator 20. A pressurizer of a large nuclear power plant is installed in a reactor coolant system as an independent component, and the temperature of a fluid in the pressurizer is markedly different from the temperature of the fluid in a reactor coolant system pipe according to operational states. In this case, a thermal stratification flow may occur in a surge line connecting the pressurizer and the coolant pipe, thereby causing a large degree of stress and requiring a space and support structures for the surge line. In the small-medium modular reactor of the related art in which the steam generator 20 is provided in the reactor vessel 10, a pressurizer 60 is integrated in an upper head 70 for removal of a surge line and an installation space. However, the complex structure of the small-medium modular reactor of the related art may limit access paths for inspection, repair, and maintenance of the inside of the pressurizer 60 and a penetration portion of the upper head 70. (Patent Document 1) Korean Patent Application Laid-open Publication No. 10-2014-0021121 (Feb. 20, 2014) One or more embodiments include an externally integrated steam generator type small modular reactor in which a steam generator is arranged along the circumference of a reactor vessel and a steam drum is arranged along the circumference of the steam generator so as to increase the heat transfer area of the steam generator, simplify the structure of the small modular reactor, and increase the spatial efficiency of the small modular reactor. Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments. According to one or more embodiments, an externally integrated steam generator type small modular reactor includes: a nuclear reactor including an upper head, a reactor vessel cylindrical shell having a cylindrical shape and coupled to the upper head, and a lower head provided on a lower portion of the reactor vessel, wherein a core is placed in the nuclear reactor; a steam generator surrounding all around the reactor vessel cylindrical shell and including a first penetration hole communicating with an inside of the nuclear reactor; and a steam drum surrounding all around the steam generator and including a second penetration hole communicating with an inside of the steam generator. The steam generator may further include: a steam generator inner shell integrated with or formed in one piece with the reactor vessel cylindrical shell and surrounding 360 degrees a circumference of the reactor vessel cylindrical shell, the steam generator inner shell sharing a portion with the reactor vessel cylindrical shell and extending in a longitudinal direction of the reactor vessel cylindrical shell; and a steam generator outer shell spaced apart from the steam generator inner shell and surrounding 360 degrees the circumference of the reactor vessel cylindrical shell, the steam generator outer shell extending in the longitudinal direction of the reactor vessel cylindrical shell, wherein the steam drum may further include: a steam drum inner shell integrated with or formed in one piece with the steam generator outer shell and surrounding 360 degrees a circumference of the steam generator, the steam drum inner shell sharing a portion with the steam generator outer shell and extending in the longitudinal direction of the reactor vessel cylindrical shell; and a steam drum outer shell spaced apart from the steam drum inner shell and surrounding 360 degrees the circumference of the steam generator, the steam drum outer shell extending in the longitudinal direction of the reactor vessel cylindrical shell, wherein the first penetration hole may be provided in a region in which the reactor vessel cylindrical shell and the steam generator inner shell are integrated with or formed in one piece with each other and may be used as a flow path allowing a fluid to flow between the inside of the nuclear reactor and the inside of the steam generator, wherein the second penetration hole may be provided in a region in which the steam generator outer shell and the steam drum inner shell are integrated with or formed in one piece with each other and may be used as a flow path allowing a fluid to flow between the inside of the steam generator and an inside of the steam drum. The steam generator may further include: a steam generator upper head connecting an upper portion of the steam generator inner shell to an upper portion of the steam generator outer shell; and a steam generator lower head connecting a lower portion of the steam generator outer shell to the reactor vessel cylindrical shell, wherein the steam generator upper head may have a semicircular or semielliptical cross section and may extend in a ring shape along the circumference of the steam generator, and the steam generator lower head may have a circular-arc cross section and may extend in a ring shape along the circumference of the steam generator. A manway may be detachably coupled to the steam generator upper head or the steam generator lower head. A plurality of first partition plates may be arranged at intervals inside the steam generator along the circumference of the steam generator, steam generator modules each including a high-temperature part and a low-temperature part may be provided in spaces separated by the first partition plates, and each of the steam generator modules may include a second partition plate separating the high-temperature part and the low-temperature part from each other. The first penetration hole may include a first entrance penetration hole communicating with the high-temperature part and a first exit penetration hole communicating with the low-temperature part; a cylindrical core support barrel assembly extending in the longitudinal direction of the reactor vessel cylindrical shell and accommodating the core may be provided inside the nuclear reactor; and the core support barrel assembly may include a core penetration hole communicating with the first entrance penetration hole, and the first exit penetration hole may communicate with a space between the reactor vessel cylindrical shell and the core support barrel assembly. A lower heat transfer tube sheet may be provided in a lower portion of the steam generator, the lower heat transfer tube sheet being coupled to the steam generator inner shell and the steam generator outer shell and having a plate shape along the circumference of the steam generator; an upper heat transfer tube sheet may be provided in an upper portion of the steam generator, the upper heat transfer tube sheet being coupled to the steam generator inner shell and the steam generator outer shell having a plate shape along the circumference of the steam generator; and the externally integrated steam generator type small modular reactor may further include a heat transfer tube coupled to the lower heat transfer tube sheet and the upper heat transfer tube sheet and extending straight from the lower heat transfer tube sheet to the upper heat transfer tube sheet. The lower heat transfer tube sheet or the upper heat transfer tube sheet may be integrated with or formed in one piece with the steam generator inner shell and the steam generator outer shell. The steam drum may further include: a steam drum upper head connecting an upper portion of the steam drum inner shell to an upper portion of the steam drum outer shell; and a steam drum lower head connecting a lower portion of the steam drum inner shell to the steam generator outer shell, wherein the steam drum upper head may have a semicircular or semielliptical cross section and may extend in a ring shape along a circumference of the steam drum, and the steam drum lower head may have a circular-arc cross section and may extend in a ring shape along the circumference of the steam drum. A steam outlet nozzle may be formed in the steam drum upper head. A moisture separator and a steam dryer may be provided in the steam drum. The externally integrated steam generator type small modular reactor may further include a circular-arc shaped shroud extending from an inside of the steam drum lower head to an inside of the steam generator outer shell, the shroud extending in a ring shape along a circumference of the steam drum lower head and a circumference of the steam generator outer shell. An electric heater may be installed on a pressurizer plate, and a surge hole may be formed in the pressurizer plate to allow a fluid to pass therethrough. A protrusion protruding inward from the nuclear reactor upper head and having a stud bolt hole may be provided on the nuclear reactor upper head protrusion, and the pressurizer plate may be coupled to the protrusion using a stud bolt. A cylindrical shell flange may protrude inward from the reactor vessel cylindrical shell and may include a stud bolt hole, an upper head flange may protrude outward from the upper head and may include a stud bolt hole, and the upper head and the reactor vessel cylindrical shell may be coupled to each other by joining the cylindrical shell flange and the upper head flange using a stud bolt. The externally integrated steam generator type small modular reactor may be manufactured by coupling a plurality of forged members to each other. A space formed on an upper portion of the reactor vessel cylindrical shell and surrounded by the steam generator inner shell may be configured to be filled with a reactor coolant and can be utilized as a refueling pool during refueling operation. Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. In this regard, the present embodiments may have different forms and should not be construed as being limited to the descriptions set forth herein. Accordingly, the embodiments are merely described below, by referring to the figures, to explain aspects of the present description. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed. One or more embodiments relate to an externally integrated steam generator type small modular reactor in which a steam generator is arranged along the circumference of a reactor vessel and a steam drum is arranged along the circumference of a steam generator so as to increase the heat transfer area of the steam generator, simplify the structure of the small modular reactor, and increase the spatial efficiency of the small modular reactor. According to an embodiment, the externally integrated steam generator type small modular reactor includes: a nuclear reactor 110 including an upper head 111, a reactor vessel cylindrical shell 112, and a lower head 113; a steam generator 130; and a steam drum 160. The externally integrated steam generator type small modular reactor is configured to increase the heat transfer area of the steam generator 130 and have a simple structure and a high degree of spatial efficiency. In the externally integrated steam generator type small modular reactor of the embodiment, the steam generator 130 surrounds the circumference of the reactor vessel cylindrical shell 112 and includes first penetration holes 120 communicating with the inside of the nuclear reactor 110. In addition, the steam drum 160 surrounds the circumference of the steam generator 130 and includes second penetration holes 150 communicating with the inside of the steam generator 130. Referring to FIG. 2, the nuclear reactor 110 includes: the upper head 111; the reactor vessel cylindrical shell 112 coupled to the upper head 111 and having a cylindrical shape; and the lower head 113 provided on a lower portion of the nuclear reactor 110. A core 114 is provided inside the nuclear reactor 110. The upper head 111 may be variously shaped. For example, the upper head 111 may have a hemispherical shape. The reactor vessel cylindrical shell 112 is coupled to the upper head 111 and extends downward from the upper head 111. The upper head 111 and the reactor vessel cylindrical shell 112 may be coupled to each other using an upper head flange 118 provided on the upper head 111 and a cylindrical shell flange 117 provided on the reactor vessel cylindrical shell 112. The lower head 113 may be variously shaped. For example, the lower head 113 may have a hemispherical shape. The steam generator 130 surrounds the circumference of the reactor vessel cylindrical shell 112 and includes the first penetration holes 120 communicating with the inside of the nuclear reactor 110. The steam generator 130 includes: a steam generator inner shell 131 integrated with or formed in one piece with the reactor vessel cylindrical shell 112 and surrounding 360 degrees the circumference of the reactor vessel cylindrical shell 112, the steam generator inner shell 131 sharing a portion with the reactor vessel cylindrical shell 112 and extending in a longitudinal direction of the reactor vessel cylindrical shell 112; and a steam generator outer shell 132 spaced apart from the steam generator inner shell 131 and surrounding 360 degrees the circumference of the reactor vessel cylindrical shell 112, the steam generator outer shell 132 extending in the longitudinal direction of the reactor vessel cylindrical shell 112. The steam generator inner shell 131 is integrated with or formed in one piece with the reactor vessel cylindrical shell 112. The steam generator outer shell 132 is spaced apart from the steam generator inner shell 131 and surrounding 360 degrees the circumference of the reactor vessel cylindrical shell 112 and extends upward from the reactor vessel cylindrical shell 112 in the longitudinal direction of the reactor vessel cylindrical shell 112 (here, the longitudinal direction of the reactor vessel cylindrical shell 112 is a direction in which the upper head 111, the reactor vessel cylindrical shell 112, and the lower head 113 are arranged). The steam generator inner shell 131 and the steam generator outer shell 132 surround the reactor vessel cylindrical shell 112 and have a doughnut-shaped cross section. Referring to FIG. 3, the steam generator inner shell 131 and the steam generator outer shell 132 have a doughnut-shaped cross section in which the nuclear reactor 110 is placed. The steam generator 130 may further include: a steam generator upper head 133 connecting an upper portion of the steam generator inner shell 131 to an upper portion of the steam generator outer shell 132; and a steam generator lower head 134 connecting a lower portion of the steam generator outer shell 132 to the reactor vessel cylindrical shell 112. The steam generator upper head 133 has a semicircular cross section and extends in a ring shape along the circumference of the steam generator 130. That is, the steam generator upper head 133 has a semicircular cross section and surrounds an upper portion of the steam generator 130 in a doughnut shape. Since the steam generator upper head 133 has a semicircular cross section, a space in which a fluid may stay may be formed. Instead of having a semicircular cross section, the steam generator upper head 133 may have another cross sectional shape such as a semielliptical shape. The steam generator lower head 134 has a circular-arc cross section and extends in a ring shape along the circumference of the steam generator 130. That is, the steam generator lower head 134 has a circular-arc cross section and connects the steam generator outer shell 132 to the reactor vessel cylindrical shell 112 while surrounding a lower portion of the steam generator 130 in a doughnut shape. Since the steam generator lower head 134 has a circular-arc cross section, a fluid may smoothly flow along the shape of the steam generator lower head 134. In a non-limiting example, the steam generator lower head 134 may have a quarter-circular cross section. However, the steam generator lower head 134 may have another circular-arc cross sectional shape. The first penetration holes 120 function as flow paths allowing a fluid to flow between the inside of the nuclear reactor 110 and the inside of the steam generator 130. That is, openings are formed in the steam generator 130 to allow a fluid to flow from or to the inside of the nuclear reactor 110. In other words, owing to the first penetration holes 120, the steam generator 130 is connected to the nuclear reactor 110 without using pipes, and a fluid may flow therebetween. The first penetration holes 120 may be provided in a region in which the steam generator inner shell 131 and the reactor vessel cylindrical shell 112 are integrated with or formed in one piece with each other. For example, the first penetration holes 120 may be formed between a lower portion of the steam generator inner shell 131 and a position at which the steam generator lower head 134 and the reactor vessel cylindrical shell 112 are coupled to each other. Referring to FIGS. 3 to 5, a plurality of first partition plates 143 are arranged at intervals inside the steam generator 130 along the circumference of the steam generator 130. The first partition plates 143 extend in the longitudinal direction of the reactor vessel cylindrical shell 112 and divide an inner space of the steam generator 130. Steam generator modules 140 each including a high-temperature part 141 and a low-temperature part 142 are arranged in the divided inner space of the steam generator 130. That is, the steam generator modules 140 are independently arranged in the inner space of the steam generator 130 divided by the first partition plates 143. Each of the steam generator modules 140 is divided into the high-temperature part 141 and the low-temperature part 142 by a second partition plate 144. Referring to FIG. 4, the high-temperature parts 141 and the low-temperature parts 142 are related to the flow of a fluid in the nuclear reactor 110 (described later). Primary coolant temperature heated to a high temperature in the core 114 flows to the upper portion of the steam generator 130 through the high-temperature parts 141, and after passing through the low-temperature parts 142, the primary cooling water flows to the core 114. Heat transfer tubes 137 are arranged in the high-temperature parts 141 and the low-temperature parts 142. A lower heat transfer tube sheet 135 coupled to the steam generator inner shell 131 and the steam generator outer shell 132 and having a plate shape along the circumference of the steam generator 130 is provided in the lower portion of the steam generator 130, and an upper heat transfer tube sheet 136 coupled to the steam generator inner shell 131 and the steam generator outer shell 132 and having a plate shape along the circumference of the steam generator 130 is provided in the upper portion of the steam generator 130. The lower heat transfer tube sheet 135 and the upper heat transfer tube sheet 136 are respectively provided in the lower and upper portions of the steam generator 130, and each of the lower heat transfer tube sheet 135 and the upper heat transfer tube sheet 136 extends along the circumference of the steam generator 130 in a doughnut shape. The lower heat transfer tube sheet 135 is placed above the steam generator lower head 134, and the upper heat transfer tube sheet 136 is placed below the steam generator upper head 133. The lower heat transfer tube sheet 135 and the upper heat transfer tube sheet 136 may be formed integrally with or in one piece with the steam generator inner shell 131 and the steam generator outer shell 132. Holes may be formed in the lower heat transfer tube sheet 135 and the upper heat transfer tube sheet 136 so as to couple the heat transfer tubes 137 to the holes. That is, the heat transfer tubes 137 may be coupled to the lower heat transfer tube sheet 135 and the upper heat transfer tube sheet 136 by inserting the heat transfer tubes 137 into the holes. The heat transfer tubes 137 are straight from the lower heat transfer tube sheet 135 to the upper heat transfer tube sheet 136, and a fluid may flow in the heat transfer tubes 137. Primary cooling water heated to a high temperature and flowing out from the core 114 flows in the heat transfer tubes 137 arranged in the high-temperature parts 141, and after passing through the heat transfer tubes 137 arranged in the high-temperature parts 141 of the steam generator 130, the primary cooling water flows in the heat transfer tubes 137 arranged in the low-temperature parts 142 in a direction from the steam generator 130 toward the core 114. Referring to FIGS. 2 and 6, the steam drum 160 surrounds the circumference of the steam generator 130 and includes the second penetration holes 150 communicating with the inside of the steam generator 130. That is, the steam drum 160 surrounds 360 degrees the steam generator 130. The steam drum 160 includes: a steam drum inner shell 161 integrated with or formed in one piece with the steam generator outer shell 132 and surrounding 360 degrees the circumference of the steam generator outer shell 132, the steam drum inner shell 161 extending in the longitudinal direction of the reactor vessel cylindrical shell 112; and a steam drum outer shell 162 spaced apart from the steam drum inner shell 161 and surrounding the circumference of the steam generator 130, the steam drum outer shell 162 extending in the longitudinal direction of the reactor vessel cylindrical shell 112. The steam drum inner shell 161 and the steam generator outer shell 132 are integrated with or formed in one piece with each other and share a shell with each other. The steam drum inner shell 161 may be integrated with or formed in one piece with the steam generator outer shell 132 and a portion of the steam generator upper head 133. The steam drum inner shell 161 extends upward from the steam generator outer shell 132 in the longitudinal direction of the reactor vessel cylindrical shell 112. The steam drum outer shell 162 is spaced apart from the steam drum inner shell 161 and surrounds 360 degrees the steam generator 130. That is, the steam drum inner shell 161 and the steam drum outer shell 162 surround the steam generator 130 and have a doughnut-shaped cross section. Referring to FIG. 6, the steam drum inner shell 161 and the steam drum outer shell 162 have a doughnut-shaped cross section in which the steam generator 130 is placed. The steam drum 160 may further include: a steam drum upper head 163 connecting an upper portion of the steam drum inner shell 161 to an upper portion of the steam drum outer shell 162; and a steam drum lower head 164 connecting a lower portion of the steam drum outer shell 162 to the steam generator outer shell 132. The steam drum upper head 163 has a semicircular cross section and extends in a ring shape along the circumference of the steam drum 160. That is, the steam drum upper head 163 has a semicircular cross section and surrounds an upper portion of the steam drum 160 in a doughnut shape. Steam outlet nozzles 165 communicating with the outside may be formed in an upper portion of the steam drum upper head 163. Steam generated in the steam generator 130 and the steam drum 160 may be discharged through the steam outlet nozzles 165. The steam drum upper head 163 may have a semicircular shape. However, the steam drum upper head 163 is not limited thereto. For example, the steam drum upper head 163 may have another shape such as a semielliptical shape. The steam drum lower head 164 has a circular-arc cross section and extends in a ring shape along the circumference of the steam drum 160. That is, the steam drum lower head 164 has a circular-arc cross section and connects the steam drum outer shell 162 to the steam generator outer shell 132 while surrounding a lower portion of the steam drum 160 in a doughnut shape. Since the steam drum lower head 164 has a circular-arc cross section, a fluid may smoothly flow along the shape of the steam drum lower head 164. In a non-limiting example, the steam drum lower head 164 may have a quarter-circular cross section. However, the steam drum lower head 164 may have another circular-arc cross sectional shape. Referring to FIG. 6, the second penetration holes 150 function as flow paths allowing a fluid to flow between the inside of the steam generator 130 and the inside of the steam drum 160. That is, openings are formed in the steam drum 160 to allow a fluid to flow to the inside of the steam generator 130. In other words, owing to the second penetration holes 150, the steam drum 160 is connected to the steam generator 130 without using pipes, and a fluid may flow therebetween. The second penetration holes 150 may be provided in a region in which the steam drum inner shell 161 and the steam generator outer shell 132 are integrated with or formed in one piece with each other. Moisture separators 166 and steam dryers 167 may be provided in the steam drum 160. The moisture separators 166 and the steam dryers 167 may be used to remove moisture from steam and then discharge dried pure steam, and since the moisture separators 166 and the steam dryers 167 are well known in the art, descriptions thereof will not be presented here. Referring to FIG. 2, a circular-arc shaped shroud 170 may extend from the inside of the steam drum lower head 164 to the inside of the steam generator outer shell 132 and may extend in a ring shape along the circumference of the steam drum lower head 164 and the circumference of the steam generator outer shell 132. That is, the shroud 170 may extend along the circular-arc shape of the steam drum lower head 164 and may further extend along the steam generator outer shell 132. The shroud 170 may be a plate dividing the inside of the steam drum 160 and the inside of the steam generator 130 and may be placed between the steam generator outer shell 132 and the heat transfer tubes 137 (that is, the heat transfer tubes 137 may be arranged in a region of the steam generator 130 located inside the shroud 170, and a separate space may be formed in a region of the steam generator 130 located outside the shroud 170). Although the inside of the steam generator 130 may be divided by the shroud 170, the shroud 170 does not extend to the lower portion of the steam generator 130. Therefore, an inner space of the lower portion of the steam generator 130 is not divided. Condensation formed by the moisture separators 166 and the steam dryers 167 provided inside the steam drum 160 may flow along the separate space formed by the shroud 170. After flowing along the separate space formed by the shroud 170, the condensation may flow back to the inside of the steam generator 130 from the lower portion of the steam generator 130. Owing to the shroud 170, condensation formed by the moisture separators 166 and the steam dryers 167 may be reused. Control rod driving devices 190 are installed in the upper head 111 of the nuclear reactor 110, and nozzles connected to a pressurizer injection system and a discharge system of a reactor coolant system are installed in the upper head 111 of the nuclear reactor 110. The control rod driving devices 190 are inserted into the upper head 111 and connected to the core 114 through guide tubes. A cylindrical shell flange 117 protruding inward from the reactor vessel cylindrical shell 112 and having stud bolt holes is provided on the reactor vessel cylindrical shell 112, and an upper head flange 118 protruding outward from the upper head 111 and having stud bolt holes is provided on the upper head 111. Referring to FIGS. 2 and 7, the upper head 111 and the reactor vessel cylindrical shell 112 may be coupled to each other by joining the upper head flange 118 and the cylindrical shell flange 117 to each other using stud bolts. For example, the upper head 111 and the reactor vessel cylindrical shell 112 may be coupled to each other using stud bolts 119. In this case, the upper head 111 and the reactor vessel cylindrical shell 112 may be easily coupled and separated. Referring to FIG. 8, a pressurizer plate 181 in which surge holes 182 are formed to allow a fluid to pass therethrough and electric heaters 183 are installed to heat a fluid may be provided in the nuclear reactor 110. For example, a pressurizer 180 including the surge holes 182, the electric heaters 183, and the pressurizer plate 181 may be provided in the upper head 111 of the nuclear reactor 110. The pressurizer 180 may adjust the inside pressure of the core 114, and a fluid may be introduced between the pressurizer plate 181 and the upper head 111 to adjust the inside pressure of the core 114. The pressurizer 180 may include a spray 184 to adjust the pressure of the fluid. The pressure of the core 114 may be adjusted using the pressurizer 180 by a well-know method, and thus a description thereof will not be presented here. The pressurizer plate 181 may be provided in a lower portion of the upper head 111 or at a position at which the reactor vessel cylindrical shell 112 and the upper head 111 meet each other. The pressurizer plate 181 may be installed using a protrusion 185 which has stud bolt holes and protrudes inward from the nuclear reactor 110 in a ring shape. The pressurizer plate 181 may be coupled to the protrusion 185 using stud bolts. Referring to FIG. 9, manways 138 are detachably coupled to the steam generator upper head 133 or the steam generator lower head 134. The manways 138 are detachably coupled to the steam generator upper head 133 or the steam generator lower head 134 using stud bolts, and maintenance work may be performed on the inside of the steam generator 130 after detaching the manways 138. In the externally integrated steam generator type small modular reactor of the embodiment, heat generated in the core 114 is distributed using a fluid. Fluid flow in the externally integrated steam generator type small modular reactor is as follows. Referring to FIGS. 2 and 3, the first penetration holes 120 connecting the steam generator 130 to the nuclear reactor 110 may include first entrance penetration holes 121 communicating with the high-temperature parts 141 of the steam generator 130 and first exit penetration holes 122 communicating with the low-temperature parts 142 of the steam generator 130. Along with this, a cylindrical core support barrel assembly 115 in which the core 114 is placed is provided in the nuclear reactor 110, and the core support barrel assembly 115 extends in the longitudinal direction of the reactor vessel cylindrical shell 112. That is, the core 114 is placed in the cylindrical core support barrel assembly 115 provided inside the nuclear reactor 110. The core support barrel assembly 115 includes core penetration holes 116 communicating with the first entrance penetration holes 121, and thus primary cooling water may flow from the core 114 to the first entrance penetration holes 121 through the core penetration holes 116. Since the first entrance penetration holes 121 communicate with the high-temperature parts 141, primary cooling water may flow from the core 114 to the high-temperature parts 141. The first exit penetration holes 122 communicate with a space formed between the reactor vessel cylindrical shell 112 and the core support barrel assembly 115. That is, after passing through the low-temperature parts 142, primary cooling water flows to the space between the reactor vessel cylindrical shell 112 and the core support barrel assembly 115 through the first exit penetration holes 122. Fluid flow in the externally integrated steam generator type small modular reactor will now be described with reference to FIG. 2. Primary cooling water is heated to a high temperature in the core 114 and then flows to the high-temperature parts 141 through the core penetration holes 116 of the core support barrel assembly 115 and the first entrance penetration holes 121. Exit nozzles 1161 connected from the reactor vessel cylindrical shell 112 to the core support barrel assembly 115 are provided under the core penetration holes 116. Owing to the exit nozzles 1161, the primary cooling water may not flow to the space between the reactor vessel cylindrical shell 112 and the core support barrel assembly 115. The primary cooling water introduced into the high-temperature parts 141 flows along the heat transfer tubes 137 to the upper head 133 of the steam generator 130 through the lower heat transfer tube sheet 135. At this time, a region among the steam generator inner shell 131, the steam generator outer shell 132, and the heat transfer tubes 137 is filed with secondary cooling water, and thus heat is exchanged between the primary cooling water flowing in the heat transfer tubes 137 and the secondary cooling water flowing outside the heat transfer tubes 137 (that is, the inside of the steam generator 130 is filled with the secondary cooling water except for the heat transfer tubes 137). Referring to FIG. 4, primary cooling water introduced into the high-temperature parts 141 flows to the low-temperature parts 142 through the upper heat transfer tube sheet 136 and the steam generator upper head 133. The primary cooling water introduced into the low-temperature parts 142 flows along the heat transfer tubes 137 to the lower portion of the steam generator 130, and thus heat exchange occurs once again between the primary cooling water flowing in the heat transfer tubes 137 and the secondary cooling water filled outside the heat transfer tubes 137. The primary cooling water flows from the low-temperature parts 142 to the first exit penetration holes 122 through the lower heat transfer tube sheet 135 and then flows to the lower head 113 through the space between the reactor vessel cylindrical shell 112 and the core support barrel assembly 115. Thereafter, the primary cooling water flows back to the core 114 from the lower head 113, and thus the primary cooling water may be reused. In this case, reactor coolant pumps 123 may be provided at the first exit penetration holes 122 for smooth fluid flow. The secondary cooling water may be filled among the steam generator inner shell 131, the steam generator outer shell 132, and the heat transfer tubes 137 by using feed water nozzles 139 and supply water distributors 1391 provided in a lower region of the steam generator outer shell 132. While the secondary cooling water flows outside the heat transfer tubes 137 toward the upper portion of the steam generator 130, the secondary cooling water changes heat with the primary cooling water flowing inside the heat transfer tubes 137 and is thus heated and changed to steam by heat received from the primary cooling water. The steam and remaining heated secondary cooling water are introduced into the steam drum 160 through the second penetration holes 150 and are increased in the degree of dryness and changed into saturated steam while passing through the moisture separators 166 and the steam dryers 167 of the steam drum 160, and the saturated steam is discharged through the steam outlet nozzles 165. Owing to the shroud 170, condensation formed by the moisture separators 166 and the steam dryers 167 may be reused as secondary cooling water. The shroud 170 extends from a lower portion of the steam drum lower head 164 to the steam generator outer shell 132 and divides inner spaces of the steam drum 160 and the steam generator 130. A fluid condensed by the moisture separators 166 and the steam dryers 167 flows downward along the shroud 170 toward the lower portion of the steam generator 130 and is then reused as secondary cooling water. Since the shroud 170 does not extend to the lower portion of the steam generator 130, a space in the lower portion of the steam generator 130 is not divided by the shroud 170. Therefore, after flowing along the shroud 170, secondary cooling water may flow from the lower portion of the steam generator 130 to the inside of the steam generator 130 through the supply water distributors 1391 and may be reused in the steam generator 130. According to an embodiment, when nuclear fuel of the core 114 of the externally integrated steam generator type small modular reactor is replaced, the upper head 111 may be detached and lifted, and an upper portion of the nuclear reactor 110 may be filled with water (refueling water) so as to block radiation passing through the upper portion of the nuclear reactor 110. Since the steam generator inner shell 131 extends upward from the reactor vessel cylindrical shell 112, a space 1311 surrounded by the steam generator inner shell 131 is formed on an upper portion of the reactor vessel cylindrical shell 112 (since the steam generator inner shell 131 surrounds the reactor vessel cylindrical shell 112 in a ring shape, the space 1311 surrounded by the steam generator inner shell 131 has a cylindrical shape). The cylindrical space 1311 surrounded by the steam generator inner shell 131 may be filled with a fluid after the upper head 111 is detached and lifted, and thus the steam generator inner shell 131 may function as a water pool (refueling water pool). In this manner, water for blocking radiation passing through the upper portion of the nuclear reactor 110 may be filled in the cylindrical space 1311 surrounded by the steam generator inner shell 131. The externally integrated steam generator type small modular reactor of the embodiment may have the following effects. In the externally integrated steam generator type small modular reactor of the embodiment, the steam generator 130 is arranged along the circumference of the nuclear reactor 110, and the steam drum 160 is arranged along the circumference of the steam generator 130. Therefore, the heat-transfer area of the steam generator 130 may be increased, and the externally integrated steam generator type small modular reactor may have a simple structure and a high degree of space utilization efficiency. That is, owing to the concentric structure formed by arranging the steam generator 130 along the outer circumference of the nuclear reactor 110 and the steam drum 160 along the outer circumference of the steam generator 130, problems relating to spatial efficiency may be solved. Since structures such as the steam generator 130 and the steam drum 160 are spatially separated from the inside of the nuclear reactor 110, the inside space of the nuclear reactor 110 may be efficiently used, and thus components such as the pressurizer 180 may be easily placed in the nuclear reactor 110. In addition, since the steam drum 160 is arranged along the circumference of the steam generator 130 and the second penetration holes 150 are formed in the steam drum 160, the heat transfer tubes 137 of the steam generator 130 may be completely immersed in a liquid-phase fluid, and thus the heat transfer tubes 137 may not be overheated and damaged. The first penetration holes 120 are provided in a structure in which the reactor vessel cylindrical shell 112 and the steam generator inner shell 131 are integrated with or formed in one piece with each other, and the second penetration holes 150 are provided in a structure in which the steam generator outer shell 132 and the steam drum inner shell 161 are integrated with or formed in one piece with each other. Therefore, the externally integrated steam generator type small modular reactor of the embodiment may be designed without using pipes. Large nuclear power plants of the related art use pipes, and thus the risk of pipe break is always present. However, the embodiment realizes designs not using pipes, and thus dynamic loads caused by pipe break may not be applied to components, structures, and systems, and thus the amount of engineering work for designing and analysis may be reduced. According to the embodiment, the steam generator 130 is arranged along the circumference of the reactor vessel cylindrical shell 112, and thus the design of the steam generator 130 may be easily modified. In small-medium modular reactors of the related art, a steam generator is integrated with an inner side of a nuclear reactor, and thus it is difficult to change the design of the steam generator due to a limited space of the nuclear reactor. According to the embodiment, however, the steam generator 130 is arranged along the circumference of the reactor vessel cylindrical shell 112, and thus if necessary, the design of the steam generator 130 may be easily modified. Owing to the same reason, the design of the steam drum 160 may be easily modified. In the small-medium modular reactor of the related art, a complex structure is used to maintain a pressure boundary between primary cooling water used in the core 30 and secondary cooling water used in the steam generator 20 provided in the reactor vessel 10. In addition, since the pressure boundary between primary cooling water and secondary cooling water is scattered in the reactor vessel 10, a complex structure is required to maintain the pressure boundary. According to the embodiment, however, since the steam generator 130 is arranged along the circumference of the reactor vessel cylindrical shell 112, space may be easily utilized, and a pressure boundary of cooling water may be simply maintained using the lower heat transfer tube sheet 135, the upper heat transfer tube sheet 136, and the heat transfer tubes 137 provided in the steam generator 130. In addition, since the steam generator modules 140 each including the high-temperature part 141 and the low-temperature part 142 are independently provided in the steam generator 130, the number of the steam generator modules 140 may be increased according to the design and capacity of the reactor coolant system. According to the embodiment, secondary cooling water may be reused owing to the shroud 170. In addition, although the heat transfer tubes 137 of the steam generator 130 of the embodiment are straight, the steam generator 130 may have the same function as a U-tube type steam generator owing to the steam generator upper head 133. Along with this, the manways 138 are detachably provided in the steam generator upper head 133 or the steam generator lower head 134. Owing to the manways 138, maintenance of the steam generator 130 may be easily performed, and since the heat transfer tubes 137 of the steam generator 130 are straight, the heat transfer tubes 137 may be easily replaced compared to heat transfer U-tubes. In an integration design of the related art for installing a pressurizer in a nuclear reactor, access paths for inspection and maintenance of the inside of the pressurizer and a penetration portion of a reactor upper head are limited. In the externally integrated steam generator type small modular reactor of the embodiment, however, the protrusion 185 is provided inside the nuclear reactor 110, and the pressurizer plate 181 is coupled to the protrusion 185 using stud bolts. Therefore, the pressurizer plate 181 may be easily detached, and inspection and maintenance may be easily performed on the inside of the pressurizer 180. In addition, according to the embodiment, the upper head 111 and the reactor vessel cylindrical shell 112 are coupled to each other by joining the cylindrical shell flange 117 provided on the reactor vessel cylindrical shell 112 to the upper head flange 118 provided on the upper head 111 by using stud bolts 119. Therefore, the upper head 111 may be easily detached from the reactor vessel cylindrical shell 112, and thus an access path for inspection and maintenance of a penetration portion of the upper head 111 of the nuclear reactor 110 may be secured. In addition, when nuclear fuel of the core 114 is replaced, the upper head 111 is detached and lifted, and the core 114 is replaced. Radiation passing through the upper portion of the nuclear reactor 110 is blocked when the core 114 is replaced, and to this end, the upper portion of the nuclear reactor 110 is filled with water (refueling water). According to the embodiment, the cylindrical space 1311 surrounded by the steam generator inner shell 131 is provided on the upper portion of the reactor vessel cylindrical shell 112. Therefore, the cylindrical space 1311 may be used as a refueling water pool to fill water (refueling water) therein when the core 114 is replaced, and thus radiation passing through the upper portion of the nuclear reactor 110 may be blocked during the replacement of the core 114. According to the externally integrated steam generator type small modular reactor of the embodiment, the heat-transfer area of the steam generator 130 may be increased. In addition, since pipe break is prevented, weight reduction, relaxation of environmental qualification conditions, and reduction in the capacity of a safe injection system for emergency core cooling may be achieved. In addition, since the steam generator 130 and the steam drum 160 are integrated with the outer side of the nuclear reactor 110, space utilization efficiency may be increased, and maintenance work may be easily performed. Furthermore, since the steam generator 130 is provided outside the nuclear reactor 110, the capacity and size of the steam generator 130 may be flexibly determined. The externally integrated steam generator type small modular reactor of the embodiment may be manufactured as follows. The externally integrated steam generator type small modular reactor of the embodiment may be manufactured by coupling a plurality forged members or materials to each other. Since the steam generator 130 and the steam drum 160 are arranged in a ring shape along the circumference of the nuclear reactor 110, formation of particular structures such as joining and welding of vessels or shells should be guaranteed. Thus, the externally integrated steam generator type small modular reactor of the embodiment may be manufactured by manufacturing a plurality forged members and welding the forged members. Referring to FIG. 10, the forged members may be distinguished as follows: a forged member for the cylindrical shell flange 117 and the steam generator inner shell 131; a forged member for the reactor vessel cylindrical shell 112 integrated with or formed in one piece with the steam generator inner shell 131; a forged member for the reactor vessel cylindrical shell 112, the lower heat transfer tube sheet 135, and the steam generator outer shell 132; a forged member for the steam generator lower head 134; a forged member for the steam generator inner shell 131, the upper heat transfer tube sheet 136, and the steam generator outer shell 132; a forged member for the steam generator upper head 133 and the steam drum inner shell 161; a forged member for the steam generator inner shell 131; a forged member for the steam generator outer shell 132; a forged member for the reactor vessel cylindrical shell 112; a forged member for the steam drum lower head 164; a forged member for the steam drum outer shell 162; a forged member for the steam drum inner shell 161; a forged member for the steam drum upper head 163; a forged member for the upper head 111; etc. Basically, the forged members may be manufactured in a ring shape. For example, the steam generator lower head 134 may be a doughnut-shaped forged member having a circular cross section, and referring to FIG. 11, the forged member for the reactor vessel cylindrical shell 112, the lower heat transfer tube sheet 135, and the steam generator outer shell 132 may have a ring shape. The above-described forged members may be welded to each other to manufacture the externally integrated steam generator type small modular reactor of the embodiment. Distinguishment of forged members is not limited to the above-described method. That is, various forged members may be used according to manufacturing conditions. If the externally integrated steam generator type small modular reactor is manufactured using the forged members and the manufacturing method described above, the externally integrated steam generator type small modular reactor may be simply manufactured with low costs in a short construction time. As described above, according to the one or more of the above embodiments, the steam generator 130 is arranged along the circumference of the nuclear reactor 110, and the steam drum 160 is arranged along the circumference of the steam generator 130. Therefore, the heat transfer area of the steam generator 130 may be increased. In addition, since pipe break is prevented, weight reduction, relaxation of environmental qualification conditions, and reduction in the capacity of a safe injection system for emergency core cooling may be achieved. In addition, since the steam generator 130 and the steam drum 160 are integrated with the outside of the nuclear reactor 110, space utilization efficiency may be increased, and maintenance work may be easily performed. Furthermore, since the steam generator 130 is provided outside the nuclear reactor 110, the capacity and size of the steam generator 130 may be flexibly determined. It should be understood that embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each embodiment should typically be considered as available for other similar features or aspects in other embodiments. While one or more embodiments have been described with reference to the figures, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the disclosure as defined by the following claims.
	claims	1. An apparatus comprising:a fuel element for a fuel assembly, the fuel element having a tubular interior volume and storing a fissionable composition within at least a portion of the tubular interior volume, the fissionable composition in thermal transfer contact with an interior surface of the fuel element and defined by a smear density profile that includes at least five different smear densities that selectively vary with position along a longitudinal axis of the fuel element and includes:at least one region of locally increased smear density positioned to correspond to at least one region of locally decreased neutron flux, andat least one region of locally decreased smear density positioned to correspond to at least one region of locally increased neutron flux. 2. The apparatus of claim 1, wherein the smear density profile includes multiple regions of locally increased smear density corresponding to regions of locally decreased neutron flux. 3. The apparatus of claim 1, wherein the smear density profile approximates an inverted Gaussian shape. 4. The apparatus of claim 1, wherein the smear density profile varies according to a step function. 5. The apparatus of claim 1, wherein the smear density profile is higher at a first end of the fuel element than at a second opposite end of the fuel element. 6. The apparatus of claim 5, wherein the first end of the fuel element is proximate a coolant entry point within the fuel assembly and the second opposite end of the fuel element is proximate a coolant exit point of the fuel assembly. 7. The apparatus of claim 1, wherein the smear density profile of the fuel element is lower in a central section of the longitudinal axis than at either a first end or a second end of the longitudinal axis. 8. The apparatus of claim 1, wherein the fuel element comprises at least three sections, a first section proximate a first longitudinal end of the fuel element, a third section proximate a second longitudinal end of the fuel element, and a second section between the first and third sections, wherein an average smear density of the first section is greater than an average smear density of the second section, and wherein an average smear density of the third section is greater than the smear density of the second section. 9. The apparatus of claim 8, wherein the average smear density of the third section is less than the average smear density of the first section. 10. The apparatus of claim 7, wherein the smear density profile of the fuel element is not symmetrical around the central section. 11. The apparatus of claim 10, wherein the smear density profile is higher at a first end of the fuel element than at a second opposite end of the fuel element. 12. The apparatus of claim 1, wherein the fissionable composition comprises a fissionable metal sponge. 13. The apparatus of claim 1, wherein the fissionable composition comprises fuel pellets. 14. An apparatus comprising:a fuel element having an interior volume with a fissionable composition within at least a portion of the interior volume, the fissionable composition in thermal transfer contact with an interior surface of the fuel element and having a smear density profile that includes, longitudinally arranged in order from a first end to a second end of the fuel element:a first section at the first end having a first average smear density,a second section having a second average smear density different than the first average smear density,a third section having a third average smear density less that the first average smear design and the second average smear density,a fourth section having a fourth average smear density greater than the third average smear density, anda fifth section having a fifth average smear density greater than the fourth average smear density. 15. The apparatus of claim 14, wherein the smear density profile approximates an inverted Gaussian shape. 16. The apparatus of claim 14, wherein the smear density profile varies according to a step function. 17. The apparatus of claim 14, wherein the fifth average smear density is greater than the first average smear density.
	summary
050376012	abstract	A nuclear power plant that is of a walk-away type with an encapsulated reaction core in a glass matrix pool having a reactive Thorium/U.sup.233 composition in a containment structure that radiates thermal energy for use in a closed gas cycle with a split path having a common compressor with an output that divides into a first path communicating with the thermal source and a second path communicating with an intercooler, the two paths combining in a turbine with an expander that discharges to a common collector for return to the compressor.
	summary
050733052	description	DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a process for compacting radioactive wastes wherein the method of the invention is practiced. First in step P1, a die 1 is filled with radioactive wastes, i.e., hulls (fuel claddings as sheared after use) 2, which are then pressed (precompressed) by plungers 3. The precompressed hulls 2 are placed into a treating container 5 along with other blocks of waste 4, if any (step P2). The amount of waste 6 thus charged in is such that a clearance of predetermined thickness will be left inside the container 5 at its upper end. A metal powder, ceramic powder or like particulate material is filled into the clearance to form a filter layer 7 (step P3). The filter layer 7 is so formed as to fulfill the requirements represented by the hatched area of the graph of FIG. 2. More specifically stated, the mean particle size of the particulate material forming the filter layer 7 and the thickness of the layer 7 need to fulfill one of the following requirements. (1) The mean particle size is not smaller than 40 .mu.m to less than 105 .mu.m, and the thickness is at least 5 mm. PA0 (2) The mean particle size is not smaller than 105 .mu.m to not greater than 210 .mu.m, and assuming that the mean particle size is d .mu.m and the thickness of the layer is D mm, the layer 7 has the following relationship between this size and the thickness. EQU D.gtoreq.(20/105).times.d-15 The reason for determining these requirements will be described later. The clearance inside the container 5 around the waste 6 to be treated is also filled up with the metal powder or like particulate material. Next, the opening of the treating container 5 is closed with a closure 9 provided with an evacuating pipe 8, and the closure 9 is joined to the container 5 by welding the outer periphery of the closure to the container (step P4). The evacuating pipe 8 is then connected to a vacuum pump 10, which in turn is operated to evacuate the interior of the container 5 (step P5). At this time, the gas inside the treating container 5 is drawn out of the container through the interstices between the particles forming the filter layer 7, whereas the radioactive substance separating off the waste 6 is blocked by the filter layer 7 which fulfills the foregoing requirement, and is prevented from being led out of the container. After the container has been evacuated completely in this way, the evacuating pipe 8 is collapsed by a sealing device 11 to seal off the container 5 (step P6), which is then checked for leaks (step P7). The container 5 is compressed hot in its entirety by HIP (step P8) or hot press (step P9), whereby the radioactive waste 6 accommodated in the container 5 is compacted and further made stabilized through diffusion and bonding actions between the blocks of waste treated. FIG. 3 shows the result of a simulation test conducted for determining the requirements for the filter layer 7 using as a simulated radioactive powder a commercial clay powder (trade name: Arizona Roaddust) which is widely used for filter trapping tests. A 5 g quantity of the clay powder was passed through a glass tube, 30 mm in diameter, at a flow rate of 22.5 liters/min. The glass tube was provided at an intermediate portion thereof with a filter layer having a predetermined thickness and formed of globular stainless steel particles with a predetermined size. The clay powder passing through the filter layer was trapped with a membrane filter, 0.8 .mu.m in pore size, to measure the amount thereof. Table 1 below shows the particle size distribution of the clay powder. Table 2 shows the particles sizes of stainless steel powders used for forming different filter layers, and the thicknesses of the layers. With reference to FIG. 3, the simulated radioactive powder can be collected 100% when the layer is made of particles of up to 105 .mu.m in size and has a thickness of 5 mm. Further with particles of 210 .mu.m in size, a collection efficiency of 100% can be achieved if the layer is 25 mm in thickness. However, if the particle size exceeds 210 .mu.m, the improvement in the collection efficiency is small even when the layer has a thickness of larger than 25 mm, and it is substantially impossible to achieve a collection efficiency of 100%. When the particle size is less than 40 .mu.m, the interstices between the particles are too small, with the result that the layer causes an exceedingly great pressure loss and offers great resistance, hence a reduced evacuation efficiency. Because of such limitations of particle size, the thickness of the layer must be at least 5 mm at all times. Consequently, the contamination due to the aspiration of radioactive substance can be completely prevented with use of filters fulfilling the requirements represented by the hatched area of FIG. 2. TABLE 1 ______________________________________ Particle Size Distribution of Clay Powder ______________________________________ Particle size (.mu.m) <1 1.5 2 3 4 6 8 12 Proportion (%) 4.4 2.1 6.6 6.7 4.3 6.5 6.3 7.7 Particle size (.mu.m) 16 24 32 48 64 96 128 192 Proportion (%) 7.0 9.8 8.3 14.4 7.4 6.7 1.3 0.5 ______________________________________ TABLE 2 ______________________________________ Requirements for Filter Layer ______________________________________ Particle size of stainless 53 105 210 297 420 steel powder (.mu.m) Thickness of layer of 5 10 15 20 25 stainless steel powder (mm) ______________________________________ The particulate materials usable for forming the filter layer 7 according to the invention include, besides metal powders and stainless steel powder as mentioned above, ceramic powders such as ZrO.sub.2 and SiO.sub.2. Further the treating container 5 is not specifically limited in shape. The same advantage as above can be obtained, for example, by stretchable or contractable containers of the bellows type. Although the present invention has been fully described by way of example with reference to the accompanying drawings, it is to be understood that various changes and modifications will be apparent to those skilled in the art. Therefore, unless otherwise such changes and modifications depart from the scope of the invention, they could be construed as being included therein.
	description	The present application is related to and claims the benefit of the earliest available effective filing date(s) from the following listed application(s) (the “Related Applications”) (e.g., claims earliest available priority dates for other than provisional patent applications or claims benefits under 35 USC §119(e) for provisional patent applications, for any and all parent, grandparent, great-grandparent, etc. applications of the Related Application(s)). All subject matter of the Related Applications and of any and all parent, grandparent, great-grandparent, etc. applications of the Related Applications is incorporated herein by reference to the extent such subject matter is not inconsistent herewith. For purposes of the USPTO extra-statutory requirements, the present application constitutes a continuation-in-part of U.S. patent application Ser. No. 12/386,495, entitled A NUCLEAR FISSION REACTOR, FLOW CONTROL ASSEMBLY, METHODS THEREFOR AND A FLOW CONTROL ASSEMBLY SYSTEM, naming Charles E. Ahlfeld, Roderick A. Hyde, Muriel Y. Ishikawa, David G. McAlees, Jon D. McWhirter, Nathan P. Myhrvold, Ashok Odedra, Clarence T. Tegreene, Thomas Allan Weaver, Charles Whitmer, Victoria Y. H. Wood, Lowell L. Wood, Jr., and George B. Zimmerman as inventors, filed Apr. 16, 2009, which is currently co-pending, or is an application of which a currently co-pending application is entitled to the benefit of the filing date. The United States Patent Office (USPTO) has published a notice to the effect that the USPTO's computer programs require that patent applicants reference both a serial number and indicate whether an application is a continuation or continuation-in-part. Stephen G. Kunin, Benefit of Prior-Filed Application, USPTO Official Gazette Mar. 18, 2003, available at http://www.uspto.gov/web/offices/com/sol/og/2003/week11/patbene.htm. The present Applicant Entity (hereinafter “Applicant”) has provided above a specific reference to the application(s) from which priority is being claimed as recited by statute. Applicant understands that the statute is unambiguous in its specific reference language and does not require either a serial number or any characterization, such as “continuation” or “continuation-in-part,” for claiming priority to U.S. patent applications. Notwithstanding the foregoing, Applicant understands that the USPTO's computer programs have certain data entry requirements, and hence Applicant is designating the present application as a continuation-in-part of its parent applications as set forth above, but expressly points out that such designations are not to be construed in any way as any type of commentary and/or admission as to whether or not the present application contains any new matter in addition to the matter of its parent application(s). This application generally relates to processes involving induced nuclear reactions and structures which implement such processes including orifices or fluid control means at inlet, outlet or coolant channels and more particularly relates to a nuclear fission reactor, flow control assembly, methods therefor and a flow control assembly system. It is known that, in an operating nuclear fission reactor, neutrons of a known energy are absorbed by nuclides having a high atomic mass. The resulting compound nucleus separates into fission products that include two lower atomic mass fission fragments and also decay products. Nuclides known to undergo such fission by neutrons of all energies include uranium-233, uranium-235 and plutonium-239, which are fissile nuclides. For example, thermal neutrons having a kinetic energy of 0.0253 eV (electron volts) can be used to fission U-235 nuclei. Fission of thorium-232 and uranium-238, which are fertile nuclides, will not undergo induced fission, except with fast neutrons that have a kinetic energy of at least 1 MeV (million electron volts). The total kinetic energy released from each fission event is about 200 MeV. This kinetic energy is eventually transformed into heat. In nuclear reactors, the afore-mentioned fissile and/or fertile material is typically housed in a plurality of closely packed together fuel assemblies, which define a nuclear reactor core. It has been observed that heat build-up may cause such closely packed together fuel assemblies and other reactor components to undergo differential thermal expansion leading to misalignment of the reactor core components. Heat build-up may also contribute to fuel rod creep that can increase risk of fuel rod swelling and fuel rod cladding rupture during reactor operation. This may increase the risk that fuel pellets might crack and/or fuel rods might bow. Fuel pellet cracking may precede pellet-cladding failure mechanisms, such as pellet-clad mechanical interaction, and lead to fission gas release. Fission gas release can produce higher than normal radiation levels in the reactor core. Fuel rod bow may lead to obstruction of coolant flow channels. Attempts have been made to provide adequate coolant flow to nuclear reactor fuel assemblies. U.S. Pat. No. 4,505,877, issued Mar. 19, 1985 in the name of Jacky Rion and titled “Device for Regulating the Flow of a Fluid”, discloses a device comprising a series of gratings perpendicular to the fluid flow and that change direction of the fluid flow. According to the Rion patent, this device is intended for use in the regulation of the direction of a cooling fluid circulating in the base of a liquid metal-cooled nuclear reactor assembly. The device is directed toward bringing about a given pressure drop for a given nominal flow rate and a given down-stream pressure, without producing cavitation. Another attempt to provide adequate coolant flow to nuclear reactor fuel assemblies is disclosed in U.S. Pat. No. 5,066,453, issued Nov. 19, 1991 in the names of Neil G. Heppenstall et al. and titled “Nuclear Fuel Assembly Coolant Control.” This patent discloses an apparatus for controlling the flow of coolant through a nuclear fuel assembly, the apparatus comprising a variable flow restrictor locatable in the fuel assembly, means responsive to neutron radiation at a location in the fuel assembly in a manner to cause neutron induced growth of the responsive means, and a connecting means for connecting the neutron radiation responsive means to the variable flow restrictor for controlling the flow of coolant through the fuel assembly. The variable flow restrictor comprises a plurality of longitudinally aligned ducts, and a plugging means having an array of plugging members locatable in some of the ducts, the plugging members being of different lengths so that longitudinal displacement of the plugging means by the connecting means progressively opens or closes some of the ducts. Yet another attempt to provide adequate coolant flow to nuclear reactor fuel assemblies is disclosed in U.S. Pat. No. 5,198,185 issued Mar. 30, 1993 in the name of John P. Church and titled “Nuclear Reactor Flow Control Method and Apparatus.” This patent appears to disclose a coolant flow distribution that results in improved flow during accident conditions without degrading flow during nominal conditions. According to this patent, a universal sleeve housing surrounds a fuel element. The universal sleeve housing has a plurality of holes to allow passage of coolant. A variation is imposed in the number and size of holes in the sleeve housings from one sleeve to another to increase amount of coolant flowing to the fuel in the center of the core and decrease, relatively, flow to the peripheral fuel. Also, according to this patent, varying the number of holes and size of holes can meet a particular power shape across the core. According to an aspect of this disclosure, there is provided a nuclear fission reactor, comprising a nuclear fission module configured to have at least a portion of a traveling burn wave at a location relative to the nuclear fission module; and a flow control assembly configured to be coupled to the nuclear fission module and configured to modulate flow of a fluid in response to the traveling burn wave at the location relative to the nuclear fission module. According to an another aspect of the disclosure there is provided a nuclear fission reactor, comprising a heat-generating nuclear fission fuel assembly configured to have at least a portion of a traveling burn wave at a location relative to the nuclear fission fuel assembly; and a flow control assembly configured to be coupled to the nuclear fission fuel assembly and capable of modulating flow of a fluid stream in response to the traveling burn wave at the location relative to the nuclear fission fuel assembly. According to yet another aspect of the disclosure there is provided, for use in a traveling wave nuclear fission reactor, a flow control assembly, comprising a flow regulator subassembly. According to another aspect of the disclosure there is provided, for use in a nuclear fission reactor, a flow control assembly, comprising a flow regulator subassembly, the flow regulator subassembly including a first sleeve having a first hole; a second sleeve configured to be inserted into the first sleeve, the second sleeve having a second hole alignable with the first hole, the first sleeve being configured to rotate for bringing the first hole into alignment with the second hole; and a carriage subassembly configured to be coupled to the flow regulator subassembly. According to still another aspect of the disclosure there is provided, for use in a traveling wave nuclear fission reactor, a flow control assembly configured to be connected to a fuel assembly, comprising an adjustable flow regulator subassembly configured to be disposed in a fluid stream. According to a further aspect of the disclosure there is provided, for use in a nuclear fission reactor, a flow control assembly configured to be connected to a fuel assembly, comprising an adjustable flow regulator subassembly configured to be disposed in a fluid stream, the adjustable flow regulator subassembly including a first sleeve having a first hole; and a second sleeve configured to be inserted into the first sleeve, the second sleeve having a second hole, the first hole being progressively alignable with the second hole, whereby a variable amount of the fluid stream flows through the first hole and the second hole as the first hole progressively aligns with the second hole, the first sleeve being configured to axially translate relative to the second sleeve for aligning the second hole with the first hole. According to an additional aspect of the disclosure there is provided, for use in a nuclear fission reactor, a flow control assembly configured to be connected to a fuel assembly, comprising an adjustable flow regulator subassembly; and a carriage subassembly coupled to the adjustable flow regulator subassembly for adjusting the adjustable flow regulator subassembly. According to another aspect of the disclosure there is provided, for use in a nuclear fission reactor, a flow control assembly couplable to a selected one of a plurality of nuclear fission fuel assemblies arranged for disposal in the nuclear fission reactor, comprising an adjustable flow regulator subassembly for modifying flow of a fluid stream flowing through the selected one of the plurality of nuclear fission fuel assemblies, the adjustable flow regulator subassembly including an outer sleeve having a plurality of first holes; an inner sleeve inserted into the outer sleeve, the inner sleeve having a plurality of second holes, the first holes being progressively alignable with the second holes for defining a variable flow area, whereby a variable amount of the fluid stream flows through the first holes and the second holes as the first holes and the second holes progressively align to define the variable flow area; and a carriage subassembly coupled to the adjustable flow regulator subassembly for adjusting the adjustable flow regulator subassembly. According to a further aspect of the disclosure there is provided a method of operating a nuclear fission reactor, comprising producing at least a portion of a traveling burn wave at a location relative to a nuclear fission module; and operating a flow control assembly coupled to the nuclear fission module to modulate flow of a fluid in response to the location relative to the nuclear fission module. According to another aspect of the disclosure there is provided a method of assembling a flow control assembly for use in a traveling wave nuclear fission reactor, comprising receiving a flow regulator subassembly. According to another aspect of the disclosure there is provided a method of assembling a flow control assembly for use in a traveling wave nuclear fission reactor, comprising receiving a carriage subassembly. According to another aspect of the disclosure there is provided a method of assembling a flow control assembly for use in a nuclear fission reactor, comprising receiving a first sleeve having a first hole; inserting a second sleeve into the first sleeve, the second sleeve having a second hole alignable with the first hole, the first sleeve being configured to rotate for axially translating the first hole into alignment with the second hole; and coupling a carriage assembly to the flow regulator subassembly. According to an additional aspect of the disclosure there is provided, for use in a traveling wave nuclear fission reactor, a flow control assembly system, comprising a flow regulator subassembly. According to another aspect of the disclosure there is provided, for use in a nuclear fission reactor, a flow control assembly system, comprising a flow regulator subassembly, the flow regulator subassembly including a first sleeve having a first hole; a second sleeve configured to be inserted into the first sleeve, the second sleeve having a second hole alignable with the first hole, the first sleeve being configured to rotate for axially translating the first hole into alignment with the second hole; and a carriage subassembly configured to be coupled to the flow regulator subassembly. According to yet another aspect of the disclosure there is provided, for use in a nuclear fission reactor, a flow control assembly system configured to be connected to a nuclear fission fuel assembly, comprising an adjustable flow regulator subassembly configured to be disposed in a fluid stream. According to another aspect of the disclosure there is provided, for use in a nuclear fission reactor, a flow control assembly system couplable to a selected one of a plurality of nuclear fission fuel assemblies disposed in the nuclear fission reactor, comprising an adjustable flow regulator subassembly for controlling flow of a fluid stream flowing through the selected one of the plurality of nuclear fission fuel assemblies, the adjustable flow regulator subassembly including an outer sleeve having a plurality of first holes; an inner sleeve inserted into the outer sleeve, the inner sleeve having a plurality of second holes, the first holes being progressively alignable with the second holes for defining a variable flow area, whereby a variable amount of the fluid stream flows through the first holes and the second holes as the first holes and the second holes progressively align to define the variable flow area; and a carriage subassembly coupled to the adjustable flow regulator subassembly for adjusting the adjustable flow regulator subassembly. A feature of the present disclosure is the provision of a flow control assembly capable of controlling flow of a fluid in response to location of a burn wave. Another feature of the present disclosure is the provision of a flow control assembly comprising a flow regulator subassembly including an outer sleeve and an inner sleeve, the outer sleeve having a first hole and the inner sleeve having a second hole alignable with the first hole, whereby an amount of a fluid stream flows through the first hole and the second hole as the second hole aligns with the first hole. An additional feature of the present disclosure is the provision of a carriage subassembly configured to be coupled to the flow regulator subassembly for carrying and configuring the flow regulator subassembly. In addition to the foregoing, various other method and/or device aspects are set forth and described in the teachings such as text (e.g., claims and/or detailed description) and/or drawings of the present disclosure. The foregoing is a summary and thus may contain simplifications, generalizations, inclusions, and/or omissions of detail; consequently, those skilled in the art will appreciate that the summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description. In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented herein. In addition, the present application uses formal outline headings for clarity of presentation. However, it is to be understood that the outline headings are for presentation purposes, and that different types of subject matter may be discussed throughout the application (e.g., device(s)/structure(s) may be described under process(es)/operations heading(s) and/or process(es)/operations may be discussed under structure(s)/process(es) headings; and/or descriptions of single topics may span two or more topic headings). Hence, the use of the formal outline headings is not intended to be in any way limiting. Moreover, the herein described subject matter sometimes illustrates different components contained within, or connected with, different other components. It is to be understood that such depicted architectures are merely exemplary, and that in fact many other architectures may be implemented which achieve the same functionality. In a conceptual sense, any arrangement of components to achieve the same functionality is effectively “associated” such that the desired functionality is achieved. Hence, any two components herein combined to achieve a particular functionality can be seen as “associated with” each other such that the desired functionality is achieved, irrespective of architectures or intermedial components. Likewise, any two components so associated can also be viewed as being “operably connected”, or “operably coupled,” to each other to achieve the desired functionality, and any two components capable of being so associated can also be viewed as being “operably couplable,” to each other to achieve the desired functionality. Specific examples of operably couplable include but are not limited to physically mateable and/or physically interacting components, and/or wirelessly interactable, and/or wirelessly interacting components, and/or logically interacting, and/or logically interactable components. In some instances, one or more components may be referred to herein as “configured to,” “configurable to,” “operable/operative to,” “adapted/adaptable,” “able to,” “conformable/conformed to,” etc. Those skilled in the art will recognize that “configured to,” “configurable to,” “operable/operative to,” “adapted/adaptable,” “able to,” “conformable/conformed to,” etc. can generally encompass active-state components and/or inactive-state components and/or standby-state components, unless context requires otherwise. With respect to the present disclosure and as previously mentioned, in many cases, for every neutron that is absorbed in a fissile nuclide, more than one neutron is liberated until the fissile nuclei are depleted. This phenomenon is used in a commercial nuclear reactor to produce continuous heat that, in turn, is used to generate electricity. However, heat damage to reactor structural materials may occur due to “peak” temperature (i.e., hot channel peaking factor) which occurs due to uneven neutron flux distribution in the reactor core. As well known in the art, neutron flux is defined as the number of neutrons passing through a unit area per unit time. This peak temperature is, in turn, due to heterogeneous control rod/fuel rod distribution. The heat damage may occur if the peak temperature exceeds material limits. In addition, reactors operating in the fast neutron spectrum may be designed to have a fertile fuel “breeding blanket” material present at the core periphery. Such reactors will tend to breed fuel into the breeding blanket material through neutron absorption. This results in an increasing power output in the reactor periphery as the reactor approaches the end of a fuel cycle. Flow of coolant through the peripheral assemblies at the beginning of a reactor fuel cycle can maintain a safe operating temperature and account for the increase in power which will occur as burn-up increases during the fuel cycle. A “reactivity” (i.e., change in reactor power) is produced because of fuel “burnup”. Burn-up is typically defined as the amount of energy generated per unit mass of fuel and is usually expressed in units of megawatt-days per metric tonne of heavy metal (MWd/MTHM) or gigawatt-days per metric tonne of heavy metal (GWd/MTHM). More specifically, reactivity change is related to the relative ability of the reactor to produce more or less neutrons than the exact amount to sustain a critical chain reaction. Responsiveness of a reactor is typically characterized as the time derivative of a reactivity change causing the reactor to increase or decrease in power exponentially. In this regard, control rods made of neutron absorbing material are typically used to adjust and control the changing reactivity. Such control rods are reciprocated in and out of the reactor core to variably control neutron absorption and thus the neutron flux level and reactivity in the reactor core. The neutron flux level is depressed in the vicinity of the control rod and potentially higher in areas remote from the control rod. Thus, the neutron flux is not uniform across the reactor core. This results in higher fuel burnup in those areas of higher neutron flux. Also, it may be appreciated by a person of ordinary skill in the art of nuclear power production, that neutron flux and power density variations are due to many factors. Proximity to a control rod may or may not be the primary factor. For example, the neutron flux typically drops significantly at core boundaries with no nearby control rod. These effects, in turn, may cause overheating or peak temperatures in those areas of higher neutron flux. Such peak temperatures may undesirably reduce the operational life of structures subjected to such peak temperatures by altering the mechanical properties of the structures. Also, reactor power density, which is proportional to the product of the neutron flux and the fissile fuel concentration, is limited by the ability of core structural materials to withstand such peak temperatures without damage. Therefore, referring to FIG. 1, by way of example only and not by way of limitation, there is shown a nuclear fission reactor, generally referred to as 10, that addresses the concerns recited hereinabove. As described more fully hereinbelow, reactor 10 may be a traveling wave nuclear fission reactor. Nuclear fission reactor 10 generates electricity that is transmitted over a plurality of transmission lines (not shown) to users of the electricity. Reactor 10 alternatively may be used to conduct tests, such as tests to determine effects of temperature on reactor materials. Referring to FIGS. 1, 1A, 1B and 2, reactor 10 comprises a nuclear fission reactor core, generally referred to as 20, that includes a plurality of nuclear fission fuel assemblies or, as also referred to herein, nuclear fission modules 30. Nuclear fission reactor core 20 is sealingly housed within a reactor core enclosure 35. By way of example only and not by way of limitation, each nuclear fission module 30 may form a hexagonally-shaped structure in transverse cross-section, as shown, so that more nuclear fission modules 30 may be closely packed together within reactor core 20, as compared to most other shapes for nuclear fission module 30, such as cylindrical or spherical shapes. Each nuclear fission module 30 comprises a plurality of fuel rods 40 for generating heat due to the aforementioned nuclear fission chain reaction process. Fuel rods 40 may be surrounded by a fuel rod canister 43, if desired, for adding structural rigidity to nuclear fission modules 30 and for segregating nuclear fission modules 30 one from another. Segregating nuclear fission modules 30 one from another avoids transverse coolant cross flow between adjacent nuclear fission modules 30. Avoiding transverse coolant cross flow prevents transverse vibration of nuclear fission modules 30. Such transverse vibration might otherwise increase risk of damage to fuel rods 40. In addition, segregating nuclear fission modules 30 one from another allows control of coolant flow on an individual module-by-module basis, as described more fully hereinbelow. Controlling coolant flow to individual, preselected nuclear fission modules 30 efficiently manages coolant flow within reactor core 20, such as directing coolant flow substantially according to the nonuniform temperature distribution in reactor core 20. Canister 43 may include an annular shoulder portion 46 (see FIG. 7) for resting bundled together fuel rods 40 thereon. The coolant may have an average nominal volumetric flow rate of approximately 5.5 m3/sec (i.e., approximately 194 cubic ft3/sec) and an average nominal velocity of approximately 2.3 msec (i.e., approximately 7.55 ft/sec) in the case of an exemplary sodium cooled reactor during normal operation. Fuel rods 40 are adjacent one to another and define a coolant flow channel 47 (see FIG. 7) therebetween for allowing flow of coolant along the exterior of fuel rods 40. Fuel rods 40 are bundled together so as to form the previously mentioned hexagonal nuclear fission modules 30. Although fuel rods 40 are adjacent to each other, fuel rods 40 are nonetheless maintained in a spaced-apart relationship by a wire wrapper 50 (see FIG. 7) that extends spirally along the length of each fuel rod 40, according to techniques known by persons of skill in the art of nuclear power reactor design. With particular reference to FIG. 1B, each fuel rod 40 has a plurality of nuclear fuel pellets 60 stacked end-to-end therein, which nuclear fuel pellets 60 are sealingly surrounded by a fuel rod cladding material 70. Nuclear fuel pellets 60 comprise the afore-mentioned fissile nuclide, such as uranium-235, uranium-233 or plutonium-239. Alternatively, nuclear fuel pellets 60 may comprise a fertile nuclide, such as thorium-232 and/or uranium-238 which will be transmuted during the fission process into the fissile nuclides mentioned immediately hereinabove. A further alternative is that nuclear fuel pellets 60 may comprise a predetermined mixture of fissile and fertile nuclides. More specifically, by way of example only and not by way of limitation, nuclear fuel pellets 60 may be made from an oxide selected from the group consisting essentially of uranium monoxide (UO), uranium dioxide (UO2), thorium dioxide (ThO2) (also referred to as thorium oxide), uranium trioxide (UO3), uranium oxide-plutonium oxide (UO—PuO), triuranium octoxide (U3O8) and mixtures thereof. Alternatively, nuclear fuel pellets 60 may substantially comprise uranium either alloyed or unalloyed with other metals, such as, but not limited to, zirconium or thorium metal. As yet another alternative, nuclear fuel pellets 60 may substantially comprise a carbide of uranium (UCx) or a carbide of thorium (ThCx). For example, nuclear fuel pellets 60 may be made from a carbide selected from the group consisting essentially of uranium monocarbide (UC), uranium dicarbide (UC2), uranium sesquicarbide (U2C3), thorium dicarbide (ThC2), thorium carbide (ThC) and mixtures thereof. As another non-limiting example, nuclear fuel pellets 60 may be made from a nitride selected from the group consisting essentially of uranium nitride (U3N2), uranium nitride-zirconium nitride (U3N2Zr3N4), uranium-plutonium nitride ((U—Pu)N), thorium nitride (ThN), uranium-zirconium alloy (UZr) and mixtures thereof. Fuel rod cladding material 70, which sealingly surrounds the stack of nuclear fuel pellets 60, may be a suitable zirconium alloy, such as ZIRCOLOY™ (trademark of the Westinghouse Electric Corporation), which has known resistance to corrosion and cracking. Cladding 70 may be made from other materials, as well, such as ferritic martensitic steels. As best seen in FIG. 1, reactor core 20 is disposed within a reactor pressure vessel 80 for preventing leakage of radioactive particles, gasses or liquids from reactor core 20 to the surrounding biosphere. Pressure vessel 80 may be steel, concrete or other material of suitable size and thickness to reduce risk of such radiation leakage and to support required pressure loads. In addition, there may be a containment vessel (not shown) sealingly surrounding parts of reactor 10 for added assurance that leakage of radioactive particles, gasses or liquids from reactor core 20 to the surrounding biosphere is prevented. Referring again to FIG. 1, a primary loop coolant pipe 90 is coupled to reactor core 20 for allowing a suitable coolant to flow through reactor core 20 in order to cool reactor core 20. Primary loop coolant pipe 90 may be made from any suitable material, such as stainless steel. It may be appreciated that, if desired, primary coolant loop pipe 90 may be made not only from ferrous alloys, but also from non-ferrous alloys, zirconium-based alloys or other structural materials or composites. The coolant carried by primary loop coolant pipe 90 may be a noble gas or mixture of noble gases. Alternatively, the coolant may be other fluids such as “light” water (H2O) or gaseous or supercritical carbon dioxide (CO2). As another example, the coolant may be a liquid metal. Such a liquid metal may be a lead (Pb) alloy, such as lead-bismuth (Pb—Bi). Further, the coolant may be an organic-based coolant, such as a polyphenyl or a fluorocarbon. In the exemplary embodiment disclosed herein, the coolant may suitably be a liquid sodium (Na) metal or sodium metal mixture, such as sodium-potassium (Na—K). As an example and depending on the particular reactor core design and operating history, normal operating temperature of a sodium-cooled reactor core may be relatively high. For instance, in the case of a 500 to 1,500 MWe sodium-cooled reactor with mixed uranium-plutonium oxide fuel, the reactor core outlet temperature during normal operation may range from approximately 510° Celsius (i.e., 950° Fahrenheit) to approximately 550° Celsius (i.e., 1,020° Fahrenheit). On the other hand, during a LOCA (Loss Of Coolant Accident) or LOFTA (Loss of Flow Transient Accident) peak fuel cladding temperatures may reach about 600° Celsius (i.e. 1,110° Fahrenheit) or more, depending on reactor core design and operating history. Moreover, decay heat build-up during post-LOCA or post-LOFTA scenarios and also during suspension of reactor operations may produce unacceptable heat accumulation. In some cases, therefore, it is appropriate to control coolant flow to reactor core 20 during both normal operation and post accident scenarios. Moreover, the temperature profile in reactor core 20 varies as a function of location. In this regard, the temperature distribution in reactor core 20 may closely follow the power density spatial distribution in reactor core 20. It is known that the power density near the center of reactor core 20 is generally higher than near the periphery of reactor core 20, in the absence of a suitable neutron reflector or neutron breeding “blanket” surrounding the periphery of reactor core 20. Thus, it is to be expected that coolant flow parameters for nuclear fission modules 30 near the periphery of reactor core 20 would be less than coolant flow parameters for nuclear fission modules 30 near the center of reactor core 20, especially at the beginning of core life. Hence, in this case, it would be unnecessary to provide the same or uniform coolant mass flow rate to each nuclear fission module 30. As described in detail hereinbelow, a technique is provided to vary coolant flow to individual nuclear fission modules 30 depending on location of nuclear fission modules 30 in reactor core 20 and desired reactor operating results. Still referring to FIG. 1, the heat-bearing coolant generated by reactor core 20 flows along a coolant flow path 95 to an intermediate heat exchanger 100, for reasons described presently. The coolant flowing along coolant flow path 95 flows through intermediate heat exchanger 100 and into a plenum volume 105 associated with intermediate heat exchanger 100. After flowing into plenum volume 105, the coolant continues through primary loop pipe 90, as shown by a plurality of arrows 107. It may be appreciated that the coolant leaving plenum volume 105 has been cooled due to the heat transfer occurring in intermediate heat exchanger 100. A first pump 110 is coupled to primary loop pipe 90, and is in fluid communication with the reactor coolant carried by primary loop pipe 90, for pumping the reactor coolant through primary loop pipe 90, through reactor core 20, along coolant flow path 95, into intermediate heat exchanger 100, and into plenum volume 105. Referring again to FIG. 1, a secondary loop pipe 120 is provided for removing heat from intermediate heat exchanger 100. Secondary loop pipe 120 comprises a secondary “hot” leg pipe segment 130 and a secondary “cold” leg pipe segment 140. Secondary cold leg pipe segment 140 is integrally formed with secondary hot leg pipe segment 130 so as to form a closed loop that defines secondary loop pipe 120, as shown. Secondary loop pipe 120, which is defined by hot leg pipe segment 130 and cold leg pipe segment 140, contains a fluid, which suitably may be liquid sodium or a liquid sodium mixture. Secondary hot leg pipe segment 130 extends from intermediate heat exchanger 100 to a steam generator and superheater combination 143 (hereinafter referred to as “steam generator 143”), for reasons described momentarily. After passing through steam generator 143, the coolant flowing through secondary loop pipe 120 and exiting steam generator 143 is at a lower temperature than before entering steam generator 143 due to the heat transfer occurring within steam generator 143. After passing through steam generator 143, the coolant is pumped, such as by means of a second pump 145, along “cold” leg pipe segment 140, which terminates in intermediate heat exchanger 100. The manner in which steam generator 143 generates steam is generally described immediately hereinbelow. Referring yet again to FIG. 1, disposed in steam generator 143 is a body of water 150 maintained at a predetermined temperature and pressure. The fluid flowing through secondary hot leg pipe segment 130 will surrender its heat to body of water 150, which is at a lower temperature than the fluid flowing through secondary hot leg pipe segment 130. As the fluid flowing through secondary hot leg pipe segment 130 surrenders its heat to body of water 150, a portion of body of water 150 will vaporize to steam 160 according to the temperature and pressure within steam generator 143. Steam 160 will then travel through a steam line 170 which has one end thereof in vapor communication with steam 160 and another end thereof in liquid communication with body of water 150. A rotatable turbine 180 is coupled to steam line 170, such that turbine 180 rotates as steam 160 passes therethrough. An electrical generator 190, which is connected to turbine 180, such as by a rotatable turbine shaft 195, generates electricity as turbine 180 rotates. In addition, a condenser 200 is coupled to steam line 170 and receives the steam passing through turbine 180. Condenser 200 condenses the steam to liquid water and passes any waste heat to a heat sink, such as a cooling tower 210, which is associated with reactor 10. The liquid water condensed by condenser 200 is pumped along steam line 170 from condenser 200 to steam generator 143 by means of a third pump 220 interposed between condenser 200 and steam generator 143. Turning now to FIGS. 2, 3 and 4, there are shown in transverse cross section, exemplary configurations for reactor core 20. In this regard, nuclear fission modules 30 may be arranged to define a hexagonally-shaped configuration, generally referred to as 230, for reactor core 20. Alternatively, nuclear fission modules 30 may be arranged to define a cylindrically-shaped configuration, generally referred to as 240, for reactor core 20. As another alternative, nuclear fission modules 30 may be arranged to define a parallelpiped-shaped configuration, generally referred to as 250, for reactor core 20. In this regard, reactor core 250 has a first end 252 and a second end 254 for reasons provided hereinbelow. Referring to FIG. 5, regardless of the configuration chosen for reactor core 20, a plurality of spaced-apart, longitudinally extending and longitudinally movable control rods 260 are symmetrically disposed within a control rod guide tube or cladding (not shown), extending the length of a predetermined number of nuclear fission modules 30. Control rods 260, which are shown disposed in a predetermined number of the hexagonally-shaped nuclear fission modules 30, control the neutron fission reaction occurring in nuclear fission modules 30. Control rods 260 comprise a suitable neutron absorber material having an acceptably high neutron absorption cross-section. In this regard, the absorber material may be a metal or metalloid selected from the group consisting essentially of lithium, silver, indium, cadmium, boron, cobalt, hafnium, dysprosium, gadolinium, samarium, erbium, europium and mixtures thereof. Alternatively, the absorber material may be a compound or alloy selected from the group consisting essentially of silver-indium-cadmium, boron carbide, zirconium diboride, titanium diboride, hafnium diboride, gadolinium titanate, dysprosium titanate and mixtures thereof. Control rods 260 will controllably supply negative reactivity to reactor core 20. Thus, control rods 260 provide a reactivity management capability to reactor core 20. In other words, control rods 260 are capable of controlling or are configured to control the neutron flux profile across reactor core 20 and thus influence the temperature profile across reactor core 20. Referring to FIGS. 5A and 5B, alternative embodiments of nuclear fission module 30 are shown. It may be appreciated that nuclear fission module 30 need not be neutronically active. In other words, nuclear fission module 30 need not contain any fissile material. In this case, nuclear fission module 30 may be a purely reflective assembly or a purely fertile assembly or a combination of both. In this regard, nuclear fission module 30 may be a breeder nuclear fission module comprising nuclear breeding material or a reflective nuclear fission module comprising reflective material. Alternatively, in one embodiment, nuclear fission module 30 may contain fuel rods 40 in combination with nuclear breeding rods or reflector rods. For example, in FIG. 5A, a plurality of fertile nuclear breading rods 270 are disposed in nuclear fission module 30 in combination with fuel rods 40. Control rods 260 may also be present. The fertile nuclear breeding material in nuclear breeding rods 270 may be thorium-232 and/or uranium-238, as mentioned hereinabove. In this manner, nuclear fission module 30 defines a fertile nuclear breeding assembly. In FIG. 5B, a plurality of neutron reflector rods 274 are disposed in nuclear fission module 30 in combination with fuel rods 40. Control rods 260 may also be present. The reflector material may be a material selected from the group consisting essentially of beryllium (Be), tungsten (W), vanadium (V), depleted uranium (U), thorium (Th), lead alloys and mixtures thereof. Also, reflector rods 274 may be selected from a wide variety of steel alloys. In this manner, nuclear fission module 30 defines a neutron reflector assembly. Moreover, it may be appreciated by a person of ordinary skill in the art of nuclear in-core fuel management that nuclear fission module 30 may include any suitable combination of nuclear fuel rods 40, control rods 260, breeding rods 270 and reflector rods 274. FIG. 5C shows another embodiment of the previously mentioned reactor core 250. In FIG. 5C, a breeding blanket comprising a plurality of breeding nuclear fission modules 276 containing fertile material are disposed around an interior periphery of parallelpiped reactor core 250. The breeding blanket breeds fissile material therein. Returning to FIG. 4, regardless of the configuration selected for nuclear fission reactor core 20, the nuclear fission reactor core 20 may be configured as a traveling wave nuclear fission reactor core, such as exemplary reactor core 250. In this regard, a comparatively small and removable nuclear fission igniter 280, that includes a moderate isotopic enrichment of nuclear fissionable material, such as, without limitation, U-233, U-235 or Pu-239, is suitably located in reactor core 250. By way of example only and not by way of limitation, igniter 280 may be located near first end 252 that is opposite second end 254 of reactor core 250. Neutrons are released by igniter 280. The neutrons that are released by igniter 280 are captured by fissile and/or fertile material within nuclear fission modules 30 to initiate the fission chain reaction. Igniter 280 may be removed once the fission chain reaction becomes self-sustaining, if desired. Referring again to FIG. 4, igniter 280 initiates a three-dimensional, traveling deflagration wave or “burn wave” 290 having a width “x”. When igniter 280 releases its neutrons to cause “ignition”, burn wave 290 travels outwardly from igniter 280 near first end 252 and toward second end 254 of reactor core 250, so as to form the propagating burn wave 290. In other words, each nuclear fission module 30 is capable of accepting at least a portion of traveling burn wave 290 as burn wave 290 propagates through reactor core 250. Speed of the traveling burn wave 290 may be constant or non-constant. Thus, the speed at which burn wave 290 propagates can be controlled. For example, longitudinal movement of the previously mentioned control rods 260 (see FIG. 5) in a predetermined or programmed manner can drive down or lower neutronic reactivity of fuel rods 40 that are disposed in nuclear fission modules 30. In this manner, neutronic reactivity of fuel rods 40 that are presently being burned at the location of burn wave 290 is driven down or lowered relative to neutronic reactivity of “unburned” fuel rods 40 ahead of burn wave 290. This result gives the burn wave propagation direction indicated by an arrow 295. The basic principles of such a traveling wave nuclear fission reactor is disclosed in more detail in co-pending U.S. patent application Ser. No. 11/605,943 filed Nov. 28, 2006 in the names of Roderick A. Hyde, et al. and titled “Automated Nuclear Power Reactor For Long-Term Operation”, which application is assigned to the assignee of the present application, the entire disclosure of which is hereby incorporated by reference. Referring to FIGS. 6 and 7, there are shown upright adjacent hexagonally-shaped nuclear fission modules 30. Only three adjacent nuclear fission modules 30 are shown, it being understood that a greater number of nuclear fission modules 30 are present in reactor core 20. In addition, each nuclear fission module 30 comprises the plurality of the previously mentioned fuel rods 40. Each nuclear fission module 30 is mounted on a horizontally extending reactor core lower support plate 360. Reactor core lower support plate 360 extends across all nuclear fission modules 30. Reactor core lower support plate 360 has a counter bore 370 therethrough for reasons provided hereinbelow. Counter bore 370 has an open end 380 for allowing flow of coolant thereinto. Horizontally extending across a top portion or exit portion of each nuclear fission module 30 and removably connected thereto is a reactor core upper support plate 400 that caps each nuclear fission module 30. Reactor core upper support plate 400 also defines a plurality of flow slots 410 for allowing flow of coolant therethrough. As previously mentioned, it is important to control the temperature of reactor core 20 and the nuclear fission modules 30 therein, regardless of the configuration selected for reactor core 20. Proper temperature control is important for several reasons. For example, heat damage may occur to reactor core structural materials if the peak temperature exceeds material limits. Such peak temperatures may undesirably reduce the operational life of structures subjected to such peak temperatures by altering the mechanical properties of the structures, particularly those properties relating to thermal creep. Also, reactor power density is limited by the ability of core structural materials to withstand such high temperatures without damage. In addition, reactor 10 alternatively may be used to conduct tests, such as tests to determine affects of temperature on reactor materials. Controlling reactor core temperature is important for successfully conducting such tests. In addition, nuclear fission modules 30 residing at or near the center of reactor core 20 may generate more heat than nuclear fission modules 30 residing at or near the periphery of reactor core 20 in the absence of a neutron reflector or neutron breeding blanket surrounding the periphery of reactor core 20. Therefore, it would be inefficient to supply a uniform coolant mass flow rate across reactor core 20 because hotter nuclear fission modules 30 near the center of reactor core 20 would involve a higher coolant mass flow rate than nuclear fission modules 30 near the periphery of reactor core 20. The disclosure herein provides a technique to address these concerns. With reference to FIGS. 1, 6 and 7, first pump 110 and primary loop pipe 90 deliver reactor coolant to nuclear fission modules 30 along a coolant flow path or fluid stream indicated by flow arrows 420. The primary coolant then continues along coolant flow path 420 and through open end 380 that is formed in lower support plate 360. As described in more detail hereinbelow, the reactor coolant can be used to remove heat from or cool selected ones of nuclear fission modules 30 at the location of traveling burn wave 290. The nuclear fission module 30 may be selected, at least in part, on the basis of whether or not burn wave 290 is located, detected, or otherwise resides within or in the vicinity of the nuclear fission module 30, as described in more detail hereinbelow. Referring again to FIGS. 1, 6 and 7, in order to achieve the desired result of cooling the selected one of nuclear fission modules 30, an adjustable flow regulator subassembly 430 is coupled to nuclear fission module 30. Flow regulator subassembly 430 controls flow of the coolant in response to the location of burn wave 290 (see FIG. 4) relative to nuclear fission modules 30 and also in response to certain operating parameters associated with nuclear fission module 30. In other words, flow regulator subassembly 430 is capable of supplying or is configured to supply a relatively lesser amount of coolant to nuclear fission module 30 when a lesser amount of burn wave 290 (i.e., lesser intensity of burn wave 290) is present within nuclear fission module 30. On the other hand, flow regulator subassembly 430 is capable of supplying or is configured to supply a relatively greater amount of coolant to nuclear fission module 30 when a greater amount of burn wave 290 (i.e., greater intensity of burn wave 290) is present within nuclear fission module 30. Presence and intensity of burn wave 290 may be identified by heat generation rate, neutron flux level, power level or other suitable operating characteristic associated with nuclear fission module 30. Referring to FIGS. 7, 8, 8A, 8B, 8C, and 8D, adjustable flow regulator subassembly 430 extends through counter bore 370 for regulating flow of fluid stream 420 into nuclear fission module 30. It will be understood by a person of ordinary skill in the art that, in order to regulate flow of fluid stream 420, flow regulator subassembly 430 provides a controllable flow resistance. Flow regulator subassembly 430 comprises a generally cylindrical first or outer sleeve 450 having a plurality of first ligaments 460, which define respective ones of a plurality of axially spaced-apart first holes or first controllable flow apertures 470 radially distributed around outer sleeve 450. Outer sleeve 450 further comprises a first nipple 480 which may have an hexagonally-shaped transverse cross section for reasons provided hereinbelow. First nipple 480 defines a threaded internal cavity 500 for reasons provided hereinbelow. Referring again to FIGS. 7, 8, 8A, 8B, 8C and 8D, flow regulator subassembly 430 further comprises a generally cylindrical second or inner sleeve 530 that is threadably received into outer sleeve 450, as disclosed in more detail hereinbelow. In one embodiment, inner sleeve 530 may be integrally formed with nuclear fission module 30 during fabrication of fission module 30, such that inner sleeve 530 is a permanent portion of nuclear fission module 30. In another embodiment, inner sleeve 530 may be removably connected to nuclear fission module 30, such that inner sleeve 530 is readily separable from nuclear fission module 30 and hence not a permanent portion of nuclear fission module 30. In either embodiment, inner sleeve 530 comprises a plurality of second ligaments 540, which define respective ones of a plurality of axially spaced-apart second holes or second controllable flow apertures 550 radially distributed around inner sleeve 530. Inner sleeve 530 further comprises an externally threaded second nipple 560 sized to be threadably received into threaded internal cavity 500 of bottom portion 490 that belongs to outer sleeve 450. A top portion 570 of inner sleeve 530 includes a cap 580, which may or may not be permanently formed with nuclear fission module 30, as previously mentioned. An internal bore 590 extends through top portion 570, including through cap 580, for passage of the coolant therethrough. Coupled to cap 580 and fuel rods 40 may be a frusto-connical funnel portion 600 having an inner surface 605 in communication with internal bore 590 and the interior of canister 43 for allowing passage of the coolant from internal bore 590 and into canister 43 where fuel rods 40 reside. As previously mentioned, nuclear fission modules 30 are capable of having or are configured to have a temperature dependent reactivity change. Thus, flow control regulator subassembly 430 is at least partially configured to control temperature within nuclear fission module 30 by controlling coolant flow into nuclear fission module 30 in order to effect such a temperature dependent reactivity change. Referring now to FIGS. 8A and 8D, bottom portion 490 of outer sleeve 450 includes an anti-rotation configuration, generally referred to as 606, to prevent relative rotation of outer sleeve 450 with respect to inner sleeve 530. In this regard, outer sleeve 450 defines a plurality of grooves, such as grooves 607a and 607b, for matingly receiving respective ones of a plurality of tabs 608a and 608b integrally formed with inner sleeve 530. Thus, as outer sleeve 450 is rotated, inner sleeve 530 is prevented from 1 rotating with respect to outer sleeve 450 due to the engagement of tabs 608a and 608b in grooves 607a and 607b, respectively. As best seen in FIG. 8E, first nipple 480 is rotatable relative to outer sleeve 450. In this regard, first nipple 480 includes an annular flange 608c that is slidably received in an annular slot 608d formed in outer sleeve 450. In this manner, first nipple 480 is freely slidably rotatable with respect to outer sleeve 450. First nipple 480 is freely slidably rotatable in either of the directions indicated by curved arrows 608e or 608f. Moreover, as first nipple 480 freely slidably rotates in one direction, such as in the direction of arrow 608e, threaded internal cavity 500 will threadably engage the external threads of second nipple 560. It may be appreciated that as the threads of internal cavity 500 threadably engage the external threads of second nipple 560, first nipple 480 will abut first sleeve 450, such as at surface 608g. As first nipple 480 abuts first sleeve 450, first sleeve 450 will upwardly translate or ascend along a longitudinal axis thereof in a direction indicated by a vertical arrow 608h. First sleeve 450 will upwardly translate or ascend only in the direction of arrow 608h due to presence of anti-rotation configuration 606. As first sleeve 450 upwardly translates or ascends a predetermined amount, first holes 470 will be progressively closed, covered, shut-off and otherwise blocked by second ligaments 540 of inner sleeve 530. Moreover, it may be appreciated that, as first sleeve 450 upwardly translates or ascends the predetermined amount, second holes 550 will be progressively closed, covered, shut off and otherwise blocked by first ligaments 460 of outer sleeve 450. Progressively closing, covering, shutting off and otherwise blocking first holes 470 and second holes 550 in this manner variably reduces flow of the coolant through first holes 470 and second holes 550. It may be appreciated that rotation of first nipple 480 in an opposite direction, such as in the direction of curved arrow 608f, causes first holes 470 and second holes 550 to be progressively opened, uncovered, revealed and otherwise unblocked for variably increasing flow of coolant through first holes 470 and second holes 550. Therefore, referring to FIGS. 7, 8, 8A, 8B, 8C, 8D, 8E, 9 and 10, flow control in nuclear fission module 30 is achieved, at least in part, by use of two distinct components, which are outer sleeve 450 and inner sleeve 530, as described presently. As previously mentioned, inner sleeve 530 may be integrally formed with nuclear fission module 30 when nuclear fission module 30 is first fabricated. However, if desired, inner sleeve may be formed separately from nuclear fission module 30, but connectable thereto, rather than being integrally formed with nuclear fission module 30 when nuclear fission module 30 is first fabricated. Inner sleeve 530 defines the plurality of second holes 550 to allow passage of the coolant into nuclear fission module 30. Outer sleeve 450 slides on top of inner sleeve 530 and has the corresponding plurality of first holes 470. Outer sleeve 450 and inner sleeve 530 are concentric and holes 470/550 are always aligned to match along the radial or rotational axis. Coolant flow is controlled by the relative positions of inner sleeve 530 and outer sleeve 450 in the axial or vertical direction. In this regard, FIG. 8B shows flow regulator subassembly 430 in a fully open configuration to fully allow fluid flow into nuclear fission module 30 and FIG. 8C shows flow regulator subassembly 430 in a fully closed configuration to fully block fluid flow into nuclear fission module 30. The engagement of tabs 608a and 608b into respective ones of grooves 607a and 607b restricts rotation of outer sleeve 450 relative to inner sleeve 530, as previously mentioned. This feature allows axial sliding of outer sleeve 450 on inner sleeve 530, but no relative rotation between outer sleeve 450 and inner sleeve 530. Fine adjustment of coolant flow is achieved by the progressive axial sliding of outer sleeve 450 relative to inner sleeve 530. Thus, rotation of first nipple 480 in direction 608e progressively opens flow regulator subassembly 430 and rotation of first nipple 480 in direction 608f progressively closes flow regulator subassembly 430 for achieving fine adjustment of holes 470/550 and thus fine adjustment of coolant flow. As best seen in FIG. 11, there may be a plurality of smaller flow regulator subassemblies, such as flow regulator subassemblies 609a and 609b, assigned to a single nuclear fission module 30. Assignment of the plurality of smaller flow regulator subassemblies 609a and 609b to a single nuclear fission module 30 provides an alternative configuration for providing coolant flow to nuclear fission module 30. In addition, assignment of the plurality of smaller flow regulator subassemblies 609a and 609b to an individual or single nuclear fission module 30 provides a possibility of substantially controlling temperature distribution within distinct portions of an individual or single nuclear fission fuel module 30. This is possible because fluid flow through each of the smaller flow regulator subassemblies 609a and 609b can be individually controlled. Referring to FIGS. 12, 13, 14, 15, and 16, there is shown flow regulator subassembly 430 in operative condition to adjust or regulate coolant fluid flow into nuclear fission module 30. Together, flow regulator subassembly 430 and a carriage subassembly 610 define a flow control assembly, generally referred to as 615, as disclosed more fully hereinbelow. In other words, flow control assembly 615 comprises flow regulator subassembly 430 and carriage subassembly 610. In this regard, carriage subassembly 610 is disposed underneath reactor core 20, such as underneath core lower support plate 360, and is capable of being coupled to or is configured to be coupled to flow regulator subassembly 430 for adjusting flow regulator subassembly 430. Adjustment of flow regulator subassembly 430 variably controls coolant flow into nuclear fission module 30, as mentioned hereinabove. Moreover, carriage subassembly 610 is capable of carrying outer sleeve 450 to nuclear fission module 30, if desired. Referring to FIGS. 13, 14, 15, and 16, the configuration of carriage subassembly 610 will now be described. Carriage subassembly 610 comprises an elongate bridge 620 spanning reactor core 20 for supporting a plurality of vertically movable socket wrenches 630 thereon. Each of socket wrenches 630 has a shaft 700 and is movably disposed in a socket well 635 for reasons disclosed hereinbelow. Connected to opposing ends of bridge 620 are a first bridge mover 640a and a second bridge mover 640b, respectively. Bridge movers 640a and 640b may be operable by means of a gear arrangement (not shown) driven by a motor (also not shown). Such a motor may be located externally to reactor core 20 to avoid the corrosive effects and heat of the coolant, such as liquid sodium, circulating through reactor core 20. Each of bridge movers 640a and 640b includes at least one wheel 650a and 650b, respectively, for allowing bridge movers 640a and 640b to simultaneously move along respective ones of transversely spaced-apart and parallel tracks 660a and 660b. Bridge movers 640a and 640b are capable of moving or are configured to move bridge 620 along tracks 660a and 660b in either of the directions indicated by arrow 663. Connected to each of tracks 660a and 660b may be a track support 665a and 665b, respectively, for supporting tracks 660a and 660b thereon. Referring to FIGS. 13, 14, 15, 16, 17, 18, and 19, socket wrenches 630 are configured to be vertically reciprocated in socket well 635 into engagement and out of engagement with first nipple 480 of outer sleeve 450. In one embodiment of carriage assembly 610, rows of socket wrenches 630 are configured to be driven by a lead screw arrangement, generally referred to as 670. Lead screw arrangement 670 has a lead screw 680 configured to threadably engage external threads 690 surrounding shaft 700 belonging to each socket wrench 630. Lead screw 680 may be driven by a mechanical drive system 705 comprising a mechanical linkage 707 coupled to lead screw 680. When mechanical linkage 707 drives lead screw 680, the lead screw 680 will turn or rotate shaft 700 due to the threaded engagement of lead screw 680 and the external threads 690 surrounding shaft 700. Turning or rotating shaft 700 will turn or rotate first nipple 480 a like amount when an hexagonally shaped recess 700a in an upper portion of shaft 700 engages hexagonally shaped first nipple 480, as shown. Referring to FIGS. 15 and 16, the manner in which each shaft 700 is selectively raised and lowered will now be described. In this regard, an externally threaded, elongate mechanical linkage extension 708 engages a first gear wheel 709 for rotating first gear wheel 709 in either of the directions indicated by curved arrows 709a and 709b. For example, as mechanical linkage extension 708 translates in one of the directions indicated by a double-headed arrow 709c, first gear wheel 709 will rotate in a first direction, such as in the direction of arrow 709a. On the other hand, as mechanical linkage extension 708 translates in an opposite direction indicated by double-headed arrow 709c, first gear wheel 709 will rotate in a second direction, such as in the direction of arrow 709b. As first gear wheel 709 rotates, such as in the direction of arrow 709a, an externally threaded centermost first rod 709d will also rotate a like amount because the external threads of first rod 709d threadably engage internal threads (not shown) formed through the center of first gear wheel 709. A second gear wheel 709e has internal threads (not shown) formed through the center thereof for threadably engaging the external threads of first rod 709d. Thus, as first rod 709d is rotated by first gear wheel 709, second gear wheel 709e will translate along first rod 709d due to the threaded engagement of first rod 709d with second gear wheel 709e. Second gear wheel 709e will translate along first rod 709d until the location of a predetermined one of shafts 700 is reached. It may be appreciated that the pitch of the external threads or gear teeth of second gear wheel 709e is such as not to create an interference with the pitch of the external threads surrounding shafts 700 so that translation of second gear wheel 709e along first rod 709e may proceed unimpeded. A third gear wheel 709f is also provided for reasons described presently. In this regard, third gear wheel 709f is coupled to an elongate second rod 709g and to an elongate third rod 709h disposed on either side of and adjacent to centermost first rod 709d. Third gear wheel 709f is driven by the previously mentioned mechanical linkage extension 708, which is movable from a first position of engagement with first gear wheel 709 to a second position of engagement with third gear wheel 709f. As third gear wheel 709f rotates, second rod 709g and third rod 709h will rotate about the longitudinal axis of first rod 709d for rotating second gear wheel 709e about the longitudinal axis of first rod 709d. As second gear wheel 709e rotates, the external threads of second gear wheel 709e will threadably engage the external threads of shaft 700 for vertically translating shaft 700. In this manner, socket wrench 630 is translated either upwardly or downwardly. It should be appreciated that mechanical linkage extension 708 may be replaced by a fourth gear wheel (not shown) or by a pulley belt assembly (also not shown). Referring to FIGS. 17, 18 and 19, in another embodiment of carriage assembly 610, socket wrenches 630 are individually rotatable and axially translatable by means of respective ones of a plurality of hermetically sealed, reversible, first electric motors 710 that are coupled to shafts 700. First electric motors 710 are hermetically sealed and may be gas cooled to protect first electric motors 710 from the corrosive effects and heat of the coolant, which may be liquid sodium or liquid sodium mixture. First electric motors 710 are configured to selectively, vertically move shafts 700. Motors 710 are reversible in the sense that rotors of motors 710 may be operated in a first direction or a second direction opposite the first direction for moving shafts 700 either upwardly or downwardly, respectively. Operation of either mechanical drive system 705 or motors 710 is suitably controlled by means of a controller or control unit 720 coupled thereto. Each motor 710 may be a custom designed direct current servomotor, such as may be available from ARC Systems, Incorporated located in Hauppauge, N.Y., USA. Controller 720 may be a custom designed motor controller, such as may be available from Bodine Electric Company located in Chicago, Ill., USA. According to another embodiment, socket wrenches 630 are individually movable by means of a radio transmitter-receiver arrangement that includes a plurality of hermetically sealed, gas cooled, reversible, second electric motors 730 that are individually operable by receipt of a radio frequency signal transmitted by a radio transmitter 740. Second electric motors 730 are hermetically sealed and may be gas cooled to protect second electric motors 730 from the corrosive effects and heat of the sodium coolant. A power supply for second electric motor 730 may be a battery or other power supply device (not shown). Second electric motors 730, that are configured to receive such a radio signal, and radio transmitter 740 may be a custom designed motor and transmitter that may be available from Myostat Motion Control, Incorporated located in Ontario, Canada. According to another embodiment, socket wrenches 630 are individually movable by means of a fiber optic transmitter-receiver arrangement, generally referred to as 742, having a plurality of fiber optic cables 745 in order to operate the reversible motor arrangement by light transmission. As best seen in FIG. 14, flow control assembly 615, and thus flow regulator subassembly 430, are capable of being operated according to or in response to an operating parameter associated with nuclear fission module 30. In this regard, at least one sensor 750 may be disposed in nuclear fission module 30 to sense status of the operating parameter. The operating parameter sensed by sensor 750 may be current temperature in nuclear fission module 30. Alternatively, the operating parameter sensed by sensor 750 may have been a previous temperature in nuclear fission module 30. In order to sense temperature, sensor 750 may be a thermocouple device or temperature sensor that may be available from Thermocoax, Incorporated located in Alpharetta, Ga. U.S.A. As another alternative, the operating parameter sensed by sensor 750 may be neutron flux in nuclear fission module 30. In order to sense neutron flux, sensor 750 may be a “PN9EB20/25” neutron flux proportional counter detector or the like, such as may be available from Centronic House, Surrey, England. As another example, the operating parameter sensed by sensor 750 may be a characteristic isotope in nuclear fission module 30. The characteristic isotope may be a fission product, an activated isotope, a transmuted product produced by breeding or other characteristic isotope. Another example is that the operating parameter sensed by sensor 750 may be neutron fluence in nuclear fission module 30. As well known in the art, neutron fluence is defined as the neutron flux integrated over a certain time period and represents the number of neutrons per unit area that passed during that time. As yet another example, the operating parameter sensed by sensor 750 may be fission module pressure, which may be a dynamic fluid pressure of approximately 10 bars (i.e., approximately 145 psi) for an exemplary sodium cooled reactor or approximately 138 bars (i.e., approximately 2000 psi) for an exemplary pressurized “light” water cooled reactor during normal operation. Alternatively, fission module pressure that is sensed by sensor 750 may be a static fluid pressure or a fission product pressure. In order to sense either dynamic or static fission module pressure, sensor 750 may be a custom designed pressure detector that may be available from Kaman Measuring Systems, Incorporated located in Colorado Springs, Colo. U.S.A. As another alternative, sensor 750 may be a suitable flow meter such as a “BLANCETT 1100 TURBINE FLOW METER”, that may be available from Instrumart, Incorporated located in Williston, Vt. U.S.A. In addition, the operating parameter sensed by sensor 750 may be determined by a suitable computer-based algorithm. A variety of algorithms can be implemented, including those such as the ideal gas law, PV=nRT, or known algorithms that produce signals indicative of pressure or temperature from direct or indirect measurement of other properties, such as flows, temperatures, electrical properties, or other. According to yet another example, the operating parameter may be operator initiated action. That is, flow regulator subassembly 430 is capable of being modified in response to any suitable operating parameter determined by a human operator. Further, flow regulator subassembly 430 is capable of being modified in response to an operating parameter determined by a suitable feedback control. Also, flow regulator subassembly 430 is capable of being modified in response to an operating parameter determined by an automated control system. Moreover, flow regulator subassembly 430 is capable of being modified in response to a change in decay heat. In this regard, decay heat decreases in the “tail” of burn wave 290 (see FIG. 4). Detection of the presence of the tail of burn wave 290 is used to decrease coolant flow rate over time to account for this decrease in decay heat found in the tail of burn wave 290. This is particularly the case when nuclear fission module 30 resides behind burn wave 290. In this case, flow regulator subassembly 430 accounts for changes in decay heat output of nuclear fission module 30 as the distance of nuclear fission module 30 from burn wave 290 changes. Sensing status of such operating parameters can facilitate suitable control and modification of flow control assembly 615 operation and thus suitable control and modification of temperature in reactor core 20. Referring to FIGS. 14, 15, 17, 18 and 19, it should be understood from the description hereinabove that flow regulator subassembly 430 is reconfigurable according to a predetermined input to controllers 720 and 740, so that controllers 720 and 740 in combination with flow regulator subassembly 430 suitably control fluid flow. That is, the predetermined input to controllers 720 and 740 is a signal produced by the previously mentioned sensor 750. For example, the predetermined input to controllers 720 and 740 may be a signal produced by the previously mentioned thermocouple or temperature sensor. Alternatively, the predetermined input to controllers 720 and 740 may be a signal produced by the previously mentioned fluid flow meter. As another alternative, the predetermined input to controllers 720 and 740 may be a signal produced by the previously mentioned neutron flux detector. As another example, signals received by controllers 720 and 740 may have been processed by reactor control systems (not shown). For example, the signals produced by such a reactor control system may come from a meter or detector and get processed either by a computer or operator in a reactor control room and then go out to carriage subassembly 610, so as to move bridge 620 and socket wrenches 630 to operate flow regulator subassembly 430. Referring to FIGS. 4, 10, and 14, it may be understood by a person of skill in the art that, based on the teachings herein, flow control assembly 615 can be capable of controlling or modulating flow of the coolant according to when traveling burn wave 290 arrives at and/or departs from nuclear fission module 30. Also, flow control assembly 615 is capable of controlling or modulating flow of the coolant according to when traveling burn wave 290 is proximate to or in the vicinity of nuclear fission module 30. Flow control assembly 615 is also capable of controlling or modulating flow of the coolant according to the previously mentioned width “x” of burn wave 290. Arrival and departure of burn wave 290, as burn wave 290 travels through nuclear fission module 30, is detected by sensing any of the previously mentioned operating parameters. For example, flow control assembly 615 is capable of controlling or modulating flow of the coolant according to heat generation rate sensed in nuclear fission module 30. It should be apparent to those skilled in the art that, in some cases, an input signal alone may control modification of flow control assembly 615 and the associated fluid flow in nuclear fission module 30. Referring to FIGS. 14 and 15, and as previously mentioned, flow control assembly 615 is operated to provide variable fluid flow to a selected one of nuclear fission modules 30. Nuclear fission module 30 is selected on the basis of the desired value for the operating parameter (e.g., temperature) in nuclear fission module 30 compared to the actual value of the operating parameter that is sensed in nuclear fission module 30. As described in more detail presently, fluid flow to nuclear fission module 30 is adjusted to bring the actual value for the operating parameter into substantial agreement with the desired value for the operating parameter. To achieve this result, bridge 620 that belongs to carriage subassembly 630 is caused to travel along tracks 660a and 660b by simultaneously actuating bridge movers 640a and 640b. As bridge 620 travels along tracks 660a and 660b, the bridge 620 will travel underneath core lower support plate 360. Bridge 620 eventually stops its travel at a predetermined location underneath core lower support plate 360 based on the actual value of the operating parameter sensed by sensors 750 in nuclear fission module 30 compared to the desired value of the operating parameter for nuclear fission module 30, as described in more fully presently. Activation and extent of travel of bridge movers 640a and 640b may be controlled by a suitable controller, such as by controllers 720 or 740. In this regard, controllers 720 or 740 will stop the travel of bridge 620 based on location of the selected one of the plurality of nuclear fission modules 30. As mentioned hereinabove, the nuclear fission module 30 to be adjusted can be selected on the basis of whether or not there is substantial agreement between the actual value of the operating parameter sensed by sensor 750 and the value of the operating parameter desired for nuclear fission module 30. Next, a selected one of the plurality of hexagonal socket wrenches 630 is caused to move vertically upwardly to matingly engage hexagonal first nipple 480. After engagement of socket wrench 630 with first nipple 480, shaft 700 is caused to rotate in order to rotate socket wrench 630. Shaft 700 is caused to rotate either by means of the previously mentioned lead screw arrangement 670, first electric motors 710, or second electric motors 730 that are coupled to controllers 720 or 740. Referring to FIGS. 7, 8, 8A, 8B, 8C, 8D, 8E, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18 and 19, after engagement with first nipple 480, rotation of socket wrench 630 in a first direction causes first or outer sleeve 450 to rotate in the same first direction. As outer sleeve 450 rotates, outer sleeve 450 will axially slidably ascend along the exterior of inner sleeve 530 due to the threaded engagement of first nipple 480 belonging to outer sleeve 450 and second nipple 560 belonging to inner sleeve 530. As outer sleeve 450 slides upwardly along inner sleeve 530, first ligaments 460 of outer sleeve 450 will progressively close, cover, shut-off and otherwise block second holes 550 of inner sleeve 530 and second ligaments 540 of inner sleeve 530 will simultaneously progressively close, cover, shut-off and otherwise block first holes 470 of outer sleeve 530. Progressively closing, covering, shutting-off and otherwise blocking first holes 470 and second holes 550 variably reduces flow of the coolant through first holes 470 and second holes 550. In this case, second holes 550 and first holes 470 may have been previously aligned for allowing full flow of coolant therethrough. Alternatively, second holes 550 and first holes 470 may have been previously partially aligned for allowing partial flow of coolant therethrough. Referring again to FIGS. 7, 8, 8A, 8B, 8C, 8D, 8E, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18 and 19, after engagement with first nipple 480, rotation of socket wrench 630 in a second direction opposite the first direction causes first or outer sleeve 450 to rotate in the second direction. As outer sleeve 450 rotates, outer sleeve 450 will axially slidably descend along the exterior of inner sleeve 530 due to the threaded engagement of first nipple 480 belonging to outer sleeve 450 and second nipple 560 belonging to inner sleeve 530. As outer sleeve 450 slides downwardly along inner sleeve 530, first ligaments 460 of outer sleeve 450 will progressively open, uncover, reveal and otherwise unblock second holes 550 of inner sleeve 530 and second ligaments 540 of inner sleeve 530 will simultaneously progressively open, uncover, reveal and otherwise unblock first holes 470 of outer sleeve 530. Progressively opening, uncovering, revealing and otherwise unblocking first holes 470 and second holes 550 variably increases flow of the coolant through first holes 470 and second holes 550. In this case, second holes 550 and first holes 470 may have been previously misaligned for restricting or disallowing flow of coolant therethrough. Alternatively, second holes 550 and first holes 470 may have been previously partially misaligned for partially restricting or partially disallowing flow of coolant therethrough. Thus, use of flow control assembly 615, which includes flow regulator subassembly 430 and carriage subassembly 610, achieves variable coolant flow on a module-by-module (i.e., fuel assembly-by-fuel assembly) basis. This allows coolant flow to be varied across reactor core 20 according to the location of burn wave 290 or the non-uniform temperature distribution in reactor core 20. Illustrative Methods Illustrative methods associated with exemplary embodiments of a nuclear fission reactor and flow control assembly will now be described. Referring to FIGS. 20A-20S, illustrative methods are provided for operating a nuclear fission reactor. Turning now to FIG. 20A, an illustrative method 760 of operating a nuclear fission reactor starts at a block 770. At a block 780, the method comprises producing at least a portion of a traveling burn wave at a location relative to a nuclear fission module. At a block 790, a flow control assembly is operated to modulate flow of a fluid in response to the location relative to the nuclear fission module. The method stops at a block 800. In FIG. 20B, an illustrative method 810 of operating a nuclear fission reactor starts at a block 820. At a block 830, at least a portion of a traveling burn wave is produced at a location relative to a nuclear fission module. At a block 840, a flow control assembly that is coupled to the nuclear fission module is operated to modulate flow of a fluid in response to the location relative to the nuclear fission module. At a block 850, a flow regulator subassembly is operated. The method stops at a block 860. In FIG. 20C, another illustrative method 870 of operating a nuclear fission reactor starts at a block 880. At a block 890, at least a portion of a traveling burn wave is produced at a location relative to a nuclear fission module. At a block 900, a flow control assembly that is coupled to the nuclear fission module is operated to modulate flow of a fluid in response to the location relative to the nuclear fission module. A flow regulator subassembly is operated at a block 910. At a block 920, the flow regulator subassembly is operated according to an operating parameter associated with the nuclear fission module. The method stops at a block 930. In FIG. 20D, a further illustrative method 940 of operating a nuclear fission reactor starts at a block 950. At a block 960, at least a portion of a traveling burn wave is produced at a location relative to a nuclear fission module. At a block 970, a flow control assembly that is coupled to the nuclear fission module is operated to modulate flow of a fluid in response to the location relative to the nuclear fission module. A flow regulator subassembly is operated at a block 980. At a block 990, the flow regulator subassembly is modified in response to an operating parameter associated with the nuclear fission module. The method stops at a block 1000. In FIG. 20E, another illustrative method 1010 of operating a nuclear fission reactor starts at a block 1020. At least a portion of a traveling burn wave is produced at a location relative to a nuclear fission module at a block 1030. At a block 1040, a flow control assembly that is coupled to the nuclear fission module is operated to modulate flow of a fluid in response to the location relative to the nuclear fission module. A flow regulator subassembly is operated at a block 1050. At a block 1060, the flow regulator subassembly is reconfigured according to a predetermined input to the flow regulator subassembly. The method stops at a block 1070. In FIG. 20F, still another illustrative method 1080 of operating a nuclear fission reactor starts at a block 1090. At least a portion of a traveling burn wave is produced at a location relative to a nuclear fission module at a block 1100. At a block 1110, a flow control assembly that is coupled to the nuclear fission module is operated to modulate flow of a fluid in response to the location relative to the nuclear fission module. At a block 1120, a flow regulator subassembly is operated. At a block 1130, a controllable flow resistance is achieved. The method stops at a block 1140. In FIG. 20G, an illustrative method 1150 of operating a nuclear fission reactor starts at a block 1160. At least a portion of a traveling burn wave is produced at a location relative to a nuclear fission module at a block 1170. At a block 1180, a flow control assembly that is coupled to the nuclear fission module is operated to modulate flow of a fluid in response to the location relative to the nuclear fission module. At a block 1190, a flow regulator subassembly is operated. At a block 1200, a second sleeve is inserted into a first sleeve, the first sleeve having a first hole and the second sleeve having a second hole alignable with the first hole. The method stops at a block 1210. In FIG. 20H, another illustrative method 1220 of operating a nuclear fission reactor starts at a block 1230. At least a portion of a traveling burn wave is produced at a location relative to a nuclear fission module at a block 1240. At a block 1250 a flow control assembly that is coupled to the nuclear fission module is operated to modulate flow of a fluid in response to the location relative to the nuclear fission module. At a block 1260, a flow regulator subassembly is operated. At a block 1270 a carriage subassembly that is coupled to the flow regulator subassembly is operated. The method stops at a block 1280. In FIG. 20I, an additional illustrative method 1290 of operating a nuclear fission reactor starts at a block 1300. At least a portion of a traveling burn wave is produced at a location relative to a nuclear fission module at a block 1310. At a block 1320, a flow control assembly that is coupled to the nuclear fission module is operated to modulate flow of a fluid in response to the location relative to the nuclear fission module. At a block 1330, a flow regulator subassembly is operated. At a block 1340, a temperature sensor is coupled to the nuclear fission module and the flow regulator subassembly. The method stops at a block 1350. In FIG. 20J, a further illustrative method 1360 of operating a nuclear fission reactor starts at a block 1370. At least a portion of a traveling burn wave is produced at a location relative to a nuclear fission module at a block 1380. At a block 1390, a flow control assembly that is coupled to the nuclear fission module is operated to modulate flow of a fluid in response to the location relative to the nuclear fission module. At a block 1400, flow of the fluid is controlled in response to the location relative to the location of the nuclear fission module by operating the flow control assembly according to when the burn wave arrives at the location relative to the location of the nuclear fission module. The method stops at a block 1410. In FIG. 20K, still another illustrative method 1420 of operating a nuclear fission reactor starts at a block 1430. At least a portion of a traveling burn wave is produced at a location relative to a nuclear fission module at a block 1440. At a block 1450, a flow control assembly that is coupled to the nuclear fission module is operated to modulate flow of a fluid in response to the location relative to the nuclear fission module. At a block 1460, flow of the fluid is controlled in response to the location relative to the nuclear fission module by operating the flow control assembly according to when the burn wave departs from the location relative to the nuclear fission module. The method stops at a block 1470. In FIG. 20L, another illustrative method 1480 of operating a nuclear fission reactor starts at a block 1490. At least a portion of a traveling burn wave is produced at a location relative to a nuclear fission module at a block 1500. At a block 1510, a flow control assembly that is coupled to the nuclear fission module is modulated to modulate flow of a fluid in response to the location relative to the nuclear fission module. At a block 1520, flow of the fluid is controlled in response to the location relative to the nuclear fission module by operating the flow control assembly according to when the burn wave is proximate to the location relative to the nuclear fission module. The method stops at a block 1530. In FIG. 20M, an illustrative method 1540 of operating a nuclear fission reactor starts at a block 1550. At least a portion of a traveling burn wave is produced at a location relative to a nuclear fission module at a block 1560. At a block 1570, a flow control assembly that is coupled to the nuclear fission module is operated to modulate flow of a fluid in response to the location relative to the nuclear fission module. At a block 1580, flow of the fluid is controlled according to a width of the burn wave. The method stops at a block 1590. In FIG. 20N, an illustrative method 1600 of operating a nuclear fission reactor starts at a block 1610. At least a portion of a traveling burn wave is produced at a location relative to a nuclear fission module at a block 1620. At a block 1630, a flow control assembly that is coupled to the nuclear fission module is operated to modulate flow of a fluid in response to the location relative to the nuclear fission module. At a block 1640, flow of the fluid is controlled by operating the flow control assembly according to a heat generation rate in the nuclear fission module. The method stops at a block 1650. In FIG. 20O, an illustrative method 1660 of operating a nuclear fission reactor starts at a block 1670. At least a portion of a traveling burn wave is produced at a location relative to a nuclear fission module at a block 1680. At a block 1690, a flow control assembly that is coupled to the nuclear fission module is operated to modulate flow of a fluid in response to the location relative to the nuclear fission module. At a block 1700, flow of a fluid is controlled by operating the flow control assembly according to a temperature in the nuclear fission module. The method stops at a block 1710. In FIG. 20P, an illustrative method 1720 of operating a nuclear fission reactor starts at a block 1730. At least a portion of a traveling burn wave is produced at a location relative to a nuclear fission module at a block 1740. At a block 1750, a flow control assembly that is coupled to the nuclear fission module is operated to modulate flow of a fluid in response to the location relative to the nuclear fission module. At a block 1760, flow of the fluid in controlled by operating the flow control assembly according to a neutron flux in the nuclear fission module. The method stops at a block 1770. In FIG. 20Q, an illustrative method 1780 of operating a nuclear fission reactor starts at a block 1790. At least a portion of a traveling burn wave is produced at a location relative to a nuclear fission module at a block 1800. At a block 1810, a flow control assembly that is coupled to the nuclear fission module is operated to modulate flow of a fluid in response to the location relative to the nuclear fission module. At a block 1820, at least a portion of the traveling burn wave is produced at a location relative to a nuclear fission fuel assembly. The method stops at a block 1830. In FIG. 20R, an illustrative method 1840 of operating a nuclear fission reactor starts at a block 1850. At least a portion of a traveling burn wave is produced at a location relative to a nuclear fission module at a block 1860. At a block 1870, a flow control assembly that is coupled to the nuclear fission module is operated to modulate flow of a fluid in response to the location relative to the nuclear fission module. At a block 1880, at least a portion of the traveling burn wave is produced at a location relative to a fertile nuclear breeding assembly. The method stops at a block 1890. In FIG. 20S, an illustrative method 1900 of operating a nuclear fission reactor starts at a block 1910. At least a portion of a traveling burn wave is produced at a location relative to a nuclear fission module at a block 1920. At a block 1930, a flow control assembly that is coupled to the nuclear fission module is operated to modulate flow of a fluid in response to the location relative to the nuclear fission module. At a block 1940, at least a portion of the traveling burn wave is produced at a location relative to a neutron reflector assembly. The method stops at a block 1950. Referring to FIGS. 21A-21H, illustrative methods are provided for assembling a flow control assembly for use in a nuclear fission reactor. Turning now to FIG. 21A, an illustrative method 1960 of assembling a flow control assembly for use in a nuclear fission reactor starts at a block 1970. At a block 1980, a flow regulator subassembly is received. The method stops at a block 1990. In FIG. 21B, another illustrative method 2000 of assembling a flow control assembly for use in a nuclear fission reactor starts at a block 2010. At a block 2020, a carriage subassembly is received. The method stops at a block 2030. In FIG. 21C, another illustrative method 2040 of assembling a flow control assembly for use in a nuclear fission reactor starts at a block 2050. A flow regulator subassembly is received at a block 2060. A first sleeve having a first hole is received at a block 2070. At a block 2080, a second sleeve is inserted into the first sleeve, the second sleeve having a second hole alignable with the first hole, and the first sleeve being configured to rotate for rotating the first hole into alignment with the second hole. At a block 2090, a carriage subassembly is coupled to the flow regulator subassembly. The method stops at a block 2100. In FIG. 21D, yet another illustrative method 2110 of assembling a flow control assembly for use in a nuclear fission reactor starts at a block 2120. A flow regulator subassembly is received at a block 2130. At a block 2140, a first sleeve is received having a first hole. At a block 2150, a second sleeve is inserted into the first sleeve, the second sleeve having a second hole alignable with the first hole. At a block 2160, a carriage subassembly is coupled to the flow regulator subassembly. At a block 2170, the carriage subassembly is coupled to the flow regulator subassembly so that the carriage subassembly carries the flow regulator subassembly to the fuel assembly. The method stops at a block 2180. In FIG. 21E, a further illustrative method 2190 of assembling a flow control assembly for use in a nuclear fission reactor starts at a block 2200. A flow regulator subassembly is received at a block 2210. At a block 2220, a first sleeve is received having a first hole. At a block 2230, a second sleeve is inserted into the first sleeve, the second sleeve having a second hole alignable with the first hole. At a block 2240, a carriage subassembly is coupled to the flow regulator subassembly. At a block 2250 the carriage subassembly is coupled to the flow regulator subassembly so that the carriage subassembly is driven by a lead screw arrangement. The method stops at a block 2260. In FIG. 21F, an illustrative method 2270 of assembling a flow control assembly for use in a nuclear fission reactor starts at a block 2280. A flow regulator subassembly is received at a block 2290. A first sleeve having a first hole is received at a block 2300. At a block 2310, a second sleeve is inserted into the first sleeve, the second sleeve having a second hole alignable with the first hole, and the first sleeve being configured to rotate for rotating the first hole into alignment with the second hole. At a block 2320, a carriage subassembly is coupled to the flow regulator subassembly. At a block 2330, the carriage subassembly is coupled so that the carriage subassembly is driven by a reversible motor arrangement. The method stops at a block 2340. In FIG. 21G, an illustrative method 2350 of assembling a flow control assembly for use in a nuclear fission reactor starts at a block 2360. A flow regulator subassembly is received at a block 2370. A first sleeve having a first hole is received at a block 2380. At a block 2390, a second sleeve is inserted into the first sleeve, the second sleeve having a second hole alignable with the first hole, and the first sleeve being configured to rotate for rotating the first hole into alignment with the second hole. At a block 2400, a carriage subassembly is coupled to the flow regulator subassembly. At a block 2410, the carriage subassembly is coupled so that the carriage subassembly is at least partially controlled by a radio transmitter-receiver arrangement operating the reversible motor arrangement. The method stops at a block 2415. In FIG. 21H, an illustrative method 2420 of assembling a flow control assembly for use in a nuclear fission reactor starts at a block 2430. A flow regulator subassembly is received at a block 2440. A first sleeve having a first hole is received at a block 2450. At a block 2460, a second sleeve is inserted into the first sleeve, the second sleeve having a second hole alignable with the first hole, and the first sleeve being configured to rotate for rotating the first hole into alignment with the second hole. At a block 2470, a carriage subassembly is coupled to the flow regulator subassembly. At a block 2480, the carriage subassembly is coupled so that the carriage subassembly is at least partially controlled by a fiber optic transmitter-receiver arrangement operating the reversible motor arrangement. The method stops at a block 2490. One skilled in the art will recognize that the herein described components (e.g., operations), devices, objects, and the discussion accompanying them are used as examples for the sake of conceptual clarity and that various configuration modifications are contemplated. Consequently, as used herein, the specific exemplars set forth and the accompanying discussion are intended to be representative of their more general classes. In general, use of any specific exemplar is intended to be representative of its class, and the non-inclusion of specific components (e.g., operations), devices, and objects should not be taken as limiting. Moreover, those persons skilled in the art will appreciate that the foregoing specific exemplary processes and/or devices and/or technologies are representative of more general processes and/or devices and/or technologies taught elsewhere herein, such as in the claims filed herewith and/or elsewhere in the present application. While particular aspects of the present subject matter described herein have been shown and described, it will be apparent to those skilled in the art that, based upon the teachings herein, changes and modifications may be made without departing from the subject matter described herein and its broader aspects and, therefore, the appended claims are to encompass within their scope all such changes and modifications as are within the true spirit and scope of the subject matter described herein. It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to claims containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that typically a disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms unless context dictates otherwise. For example, the phrase “A or B” will be typically understood to include the possibilities of “A” or “B” or “A and B.” With respect to the appended claims, those persons skilled in the art will appreciate that recited operations therein may generally be performed in any order. Also, although various operational flows are presented in a sequence(s), it should be understood that the various operations may be performed in other orders than those which are illustrated, or may be performed concurrently. Examples of such alternate orderings may include overlapping, interleaved, interrupted, reordered, incremental, preparatory, supplemental, simultaneous, reverse, or other variant orderings, unless context dictates otherwise. Furthermore, terms like “responsive to,” “related to,” or other past-tense adjectives are generally not intended to exclude such variants, unless context dictates otherwise. Therefore, what are provided are a nuclear fission reactor, flow control assembly, methods therefor and a flow control assembly system. While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. For example, a horizontally disposed orifice plate may be substituted for the flow regulator subassembly, the orifice plate having a plurality of orifices therethrough. A plurality of individually actuatable shutters would be associated with respective ones of the orifices, the shutters being capable of progressively closing and opening the orifices for regulating or modulating flow of coolant to the nuclear fission module. In addition, it may be appreciated from the teachings herein that, unlike the devices disclosed in the prior art patents cited hereinabove, the flow control assembly and system of the present disclosure dynamically change the amount of the fluid flow, avoids reliance on different and precisely constituted neutron-induced growth properties of structural materials for controlling fluid flow, and can be dynamically varied during reactor operation, as needed. Moreover, the various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.
	abstract	A molten glass discharging device provided in the bottom of a melting furnace of a waste vitrification apparatus so that the device can control the melting or cooling of a molten material. The molten glass discharging device, which is provided in the bottom of the furnace and controls discharging of a molten material, includes: an induction heating unit (110) having a discharging passage (10) along a discharging port formed in the bottom of the melting furnace; an induction coil (120) provided outside the induction heating unit (110); and a cooling unit (130) supporting the induction heating unit (110) and having a cooling conduit through which a cooling fluid circulates. The device can realize repeated discharging of the molten material by induction heating or cooling of the induction heating unit. Further, even when glass is adhered to the discharging port, the adhered glass can be easily discharged from the furnace.
	description	Field of the Invention Example embodiments relate generally to nuclear reactors, and more particularly to an external alternate cooling system of the suppression pool for a Boiling Water Nuclear Reactor (BWR). The cooling system may provide emergency cooling of the suppression pool without breaching any primary containment boundaries. Related Art FIG. 1 is a cut-away view of a conventional boiling water nuclear reactor (BWR) reactor building 5. The suppression pool 2 is a torus shaped pool that is part of the reactor building primary containment. Specifically, the suppression pool 2 is an extension of the steel primary containment vessel 3, which is located within the shell 4 of the reactor building 5. The suppression pool 2 is positioned below the reactor 1 and spent fuel pool 10, and is used to limit containment pressure increases during certain accidents. In particular, the suppression pool 2 is used to cool and condense steam released during plant accidents. For instance, many plant safety/relief valves are designed to discharge steam into the suppression pool 2, to condense the steam and mitigate undesired pressure increases. Conventionally, a BWR suppression pool 2 is approximately 140 feet in total diameter (i.e., plot plan diameter), with a 30 foot diameter torus shaped shell. During normal operation, the suppression pool 2 usually has suppression pool water in the pool at a depth of about 15 feet (with approximately 1,000,000 gallons of suppression pool water in the suppression pool 2, during normal operation). The pool 2 is conventionally cleaned and cooled by the residual heat removal (RHR) system of the BWR plant. During normal (non-accident) plant conditions, the RHR system can remove water from the suppression pool 2 (using conventional RHR pumps) and send the water through a demineralizer (not shown) to remove impurities and some radioactive isotopes that may be contained in the water. During a plant accident, the RHR system is also designed to remove some of the suppression pool water from the suppression pool 2 and send the water to a heat exchanger (within the RHR system) for cooling. During a serious plant accident, not anal plant electrical power may be disrupted. In particular, the plant may be without normal electrical power to run the conventional RHR system and pumps. If electrical power is disrupted for a lengthy period of time, water in the suppression pool may eventually boil and impair the ability of the suppression pool to condense plant steam and reduce containment pressure. In a plant emergency, use of the RHR system may cause highly radioactive water (above acceptable design limits) to be transferred between the suppression pool and RHR systems (located outside of primary containment). The transfer of the highly radioactive water between the suppression pool and RHR system may, in and of itself, cause a potential escalation in leakage of harmful radioactive isotopes that may escape the suppression pool. Additionally, radiation dosage rates in areas of the RHR system could be excessively high during an accident, making it difficult for plant personnel to access and control the system. Example embodiments provide a system for externally cooling the suppression pool for a Boiling Water Nuclear Reactor (BWR). The system may provide external cooling for the suppression pool, without breaching primary containment and without the need for normal plant electrical power. The cooling system may be operated and controlled from a remote location to protect the safety of plant personnel during a plant emergency. Example embodiments also include a method of making the system. Detailed example embodiments are disclosed herein. However, specific structural and functional details disclosed herein are merely representative for purposes of describing example embodiments. Example embodiments may, however, be embodied in many alternate forms and should not be construed as limited to only the embodiments set forth herein. Accordingly, while example embodiments are capable of various modifications and alternative forms, embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit example embodiments to the particular forms disclosed, but to the contrary, example embodiments are to cover all modifications, equivalents, and alternatives falling within the scope of example embodiments. Like numbers refer to like elements throughout the description of the figures. It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element, without departing from the scope of example embodiments. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. It will be understood that when an element is referred to as being “connected” or “coupled” to another element, it may be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements present. Other words used to describe the relationship between elements should be interpreted in a like fashion (e.g., “between” versus “directly between”, “adjacent” versus “directly adjacent”, etc.). The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises”, “comprising,”, “includes” and/or “including”, when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It should also be noted that in some alternative implementations, the functions/acts noted may occur out of the order noted in the figures. For example, two figures shown in succession may in fact be executed substantially concurrently or may sometimes be executed in the reverse order, depending upon the functionality/acts involved. FIG. 2 is an overhead view of an external cooling system 30, in accordance with an example embodiment. The external cooling system 30 may include cooling coils 26 wrapped around the suppression pool 2 and fluidly coupled to a heat sink 20 that provides external cooling for the suppression pool 2. The cooling coils 26 may be a flexible coil, branched tubing, a blanket, or any other apparatus that increases a surface area (for maximum heat transfer) between the outer shell of the suppression pool 2 and the coil 26. The cooling coils 26 may be flexible to allow the coil 26 to form around the shape of the suppression pool 2 to maximize the direct exposure between the coils 26 and the suppression pool 2 outer surface. The heat sink 20 may be a large, man-made or natural body of water. Liquid in the heat sink 20 may be water, or any other liquid fluid with a high heat capacity capable of optimizing heat exchange with the suppression pool 2. The cooler the liquid is in the heat sink 20, the more efficient the external cooling system 30 will be in cooling the suppression pool 2. The heat sink 20 may be fluidly coupled to the cooling coils 26 via pipes or tubing 24/28. Specifically, a pump 22 (connected to the heat sink 20) may discharge cool water from the heat sink 20 through a cool water inlet pipe 24 and into the cooling coils 26 wrapped around the suppression pool 2. A warm water outlet pipe 28 may discharge warm water from the cooling coils 26 back to the heat sink 20 (or, the water may alternatively be discharged to another location other than the heat sink 20). Operation and controls of the external cooling system 30 may be positioned in a remote location 31 (relative to the suppression pool 2), to protect plant personnel from exposure to primary containment during a plant accident. Specifically, the pump 22 (and/or a controller 34 used to operate the pump 22) may be located in the remote location. Likewise, a control valve 32 (and/or a controller 34 used to operate the valve 32) for controlling a flow of water through the cooling coils 26 (and opening and closing the inlet pipe 24) may also be located in the remote location 31. The pump 22 may be operated by a diesel generator, or directly by a mechanical engine, such that the operation of the pump need not rely on not anal plant electrical power (which is ideal, during a plant emergency). Alternative to the pump 22, the heat sink 20 may be located at an elevation that is above the suppression pool 2, allowing cool water from the heat sink 20 to gravity drain through the cooling coils 26 without the need for any electrical power (although this configuration, shown in FIG. 4, has the drawback of not being able to drain the water from outlet pipe 28 back into the heat sink 20). The system 30 may operate to cool the suppression pool without the need for breaching (i.e., penetrating) the integrity of the suppression pool 2 and/or any primary containment structure. The system 30 also operates without displacing water from the suppression pool 2 or otherwise removing potentially contaminated water from containment. FIG. 3 is a flowchart of a method of making an external cooling system 30, in accordance with an example embodiment. Specifically, step S40 may include wrapping a cooling coil or coils 26 around an outer surface of the suppression pool 2 (see FIG. 2). Step S42 may include fluidly coupling the cooling coils 26 to a heat sink 20. This may be accomplished by connecting inlet and outlet pipes 24/28 to the cooling coils 26 surrounding the suppression pool 2. Step S44 may include pumping cooling water from the heat sink through the cooling coils 26, via the use of a pump 22 (or, alternatively, via gravity draining). Example embodiments having thus been described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the intended spirit and scope of example embodiments, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.
	description	The disclosure is a continuation of U.S. patent application Ser. No. 13/589,155, filed Aug. 19, 2012, which is incorporated herein by reference. The present invention relates to [18F]fluoride diaryl- and aryl-fused [2.2.2]cryptate complexes suitable for performing radio-labeling reactions to generate [18F] fluorinated species for use as imaging agents. A cryptand is a phase-transfer agent used to complex [18F] fluoride anion to form [18F] fluoride cryptate complexes and that a [18F] fluorinated species defined herein comprises chemical or biological [18F] fluorinated compounds. Positron Emission Tomography (PET) relies upon the use of positron emitting radiolabeled tracer molecules and computed tomography to examine metabolic processes or to detect targets within the living body of a patient or experimental animal. Once injected, the tracer is monitored with a positron camera or a tomograph detector array. This technology can be more sensitive than scanning techniques such as magnetic resonance imaging (MRI), ultrasound imaging, or X-ray imaging. Some of the major clinical applications for PET are oncology, neurology, and cardiology. Positron emitting compounds may be employed as markers and imaging agents because their presence and location are indicated by the annihilation of a nearby electron and the consequent emission of two oppositely oriented gamma rays. Gamma ray detectors can be used to detect the event and precisely determine its location. Tracer molecules used in PET imaging are generally prepared by replacement of a group or atom in an unlabeled tracer with a radioisotope containing group or atom or by joining the tracer to a radioisotope containing atom (e.g. by chelation). Some common positron-emitting radioisotopes commonly used are: fluorine-18 (18F); carbon-11 (11C); nitrogen-13 (13N); and oxygen-15 (15O). In addition, 64Cu has been appended to tracer molecules using copper chelation chemistry (Chen et al. Bioconjug. Chem. (2004) 15: 41-49). 18F is a particularly desirable radioisotope for PET imaging since it has a longer half-life than 11C, 13N and 15O, readily forms covalent bonds, and has a short range beta+ emission that provides for high resolution in PET imaging. Natural, stable fluorine is 19F. 18F has one less neutron for that number of protons, which is why it decays by positron emission. 18F is a fluorine radioisotope which is an important source of positrons. It has a mass of 18.0009380 u and its half-life is 109.771 minutes. It decays by positron emission 97% of the time and electron capture 3% of the time. Both modes of decay yield stable oxygen-18 (18O). 18F is an important isotope in the radiopharmaceutical industry. For example, it is synthesized into fluorodeoxyglucose (FDG) for use in positron emission tomography (PET scans). It is substituted for hydroxyl and used as a tracer in the scan. Its significance is due to both its short half-life and the emission of positrons when decaying. In the radiopharmaceutical industry, the radioactive 18F must be made first as the fluoride anion (18F−) in the cyclotron. This may be accomplished by bombardment of neo-20 with deuterons, but usually is done by proton bombardment of 18O-enriched water, with high energy protons (typically ˜18 MeV protons). This produces “carrier-free” dissolved 18F-fluoride (18F−) ions in the water. Fluorine-18 is often substituted for a hydroxyl group in a radiotracer parent molecule. PET tracers often are or include a molecule of biological interest (a “biomolecule”). Biomolecules developed for use in PET have been numerous. They can be small molecules as ubiquitous as water, ammonia and glucose or more complex molecules intended for specific targeting in the patient, including labeled amino acids, nucleosides and receptor ligands. Specific examples include, but not limited to, 18F labeled fluorodeoxyglucose, methionine, deoxythymidine, L-DOPA, raclopride and Flumazenil. (Fowler J. S. and Wolf A. P. (1982), and The synthesis of carbon-11, fluorine-18 and nitrogen-13 labeled radiotracers for biomedical applications. Nucl. Sci. Ser. Natl Acad. Sci. Natl Res. Council Monogr. 1982). The 109.8 minute half-life of 18F makes rapid and automated chemistry necessary after this point. 18F-fluoride anion (18F) is often converted to a form suitable as an agent in aliphatic nucleophilic displacements or aromatic substitution reactions. 18F may be combined with a metal ion complexing agent such as cryptand or a tetrabutyl ammonium salt, a triflate, or a positively charged counter ion (including H+, K+, Na+, etc). Fluorination agents may be used in an appropriate solvent or cosolvent, including without limitation water, methanol, ethanol, THF, dimethylformamide (DMF), formamide, dimethylacetamide (DMSO), DMA, dioxane, acetonitrile, and pyridine. In nucleophilic radiofluorination, the first major step is drying the aqueous [18F] fluoride which is commonly performed in the presence of a phase-transfer catalyst under azeotropic evaporation conditions (Coenen et al., J. Labelled Compd. Radiopharm., 1986, vol. 23, pgs. 455-467). The [18F] fluoride that is solubilized or dissolved in the target water is often adsorbed on an anion exchange resin and eluted, for example, with a potassium carbonate solution (Schlyer et al., Appl. Radiat. Isot., 1990, vol. 40, pgs. 1-6). One cryptand that is available commercially is 4,7,13,16, 21,24-hexaoxa-1,10-diazabicyclo [8,8,8] hexacosan, with the tradename Kryptofix 222. Cryptand is a cage-like agent that has three ether ribs joining the nitrogens at each end. Alkali metals can be held very strongly inside the cage. The treatment with 18F− is suitably effected in the presence of a suitable organic solvent such as acetonitrile, dimethylformamide, dimethylsulphoxide, tetrahydrofuran, dioxan, 1,2 dimethoxyethane, sulpholane, N-methylpyrolidinineone, In nucleophilic fluorination reactions, anhydrous conditions are required to avoid the competing reaction with hydroxide. [Aigbirhio et al 1995 J. Fluor. Chem. 70 pp 279-87]. The removal of water from the fluoride ion is referred to as making “naked” fluoride ion. This is regarded in the prior art relating to nucleophilic fluoridation as a step necessary to increase the reactivity of fluoride as well as to avoid hydroxylated by-products resulting from the presence of water [Moughamir et al 1998 Tett. Letts. 39 pp 7305-6; and Handbook of Radiopharmaceuticals 2003 Welch & Redvanly eds. ch. 6 pp 195-227). The removal of water from the [18F] Fluoride is referred to as making “naked” [18F] Fluoride. This is regarded in the prior art relating to nucleophilic fluoridation as a step necessary to increase the reactivity of fluoride as well as to avoid hydroxylated by-products resulting from the presence of water (Moughamir et al 1998 Tett Letts; 39: 7305-6). The use of the cryptand to sequester the potassium ions avoids ion-pairing between free potassium and fluoride ions, making the fluoride anion more reactive. For example, [(2.2.2-cryptand) K+] 18F− is reacted with a protected mannose triflate; the fluoride anion displaces the triflate leaving group in an SN2 reaction, giving the protected fluorinated deoxyglucose. Base hydrolysis removes the acetyl protecting groups, giving the desired product 18FDG after removing the cryptand via ion-exchange (Fowler J S, Ido T (2002). “Initial and subsequent approach for the synthesis of 18FDG”. Semin Nucl Med 32 (1): 6-12; and Yu, S (2006). “Review of 18F-FDG synthesis and quality control”. Biomedical Imaging and Intervention Journal 2). To improve the reactivity of fluoride ion for fluoridation reactions a cationic counterion is added prior to the removal of water. The counterion should possess sufficient solubility within the anhydrous reaction solvent to maintain the solubility of the fluoride ion. Therefore, counterions that have been used include large but soft metal ions such as rubidium or caesium, potassium complexed with a cryptand such as Kryptofix™, or tetraalkylammonium salts. A preferred counterion for fluoridation reactions is potassium complexed with a cryptand such as Kryptofix™, because of its good solubility in anhydrous solvents and enhanced fluoride reactivity. Fluorodeoxyglucose (18F) or fludeoxyglucose (18F), commonly abbreviated 18F-FDG or FDG, is a radiopharmaceutical used in the medical imaging modality positron emission tomography (PET). Chemically, it is 2-deoxy-2-(18F) fluoro-D-glucose, a glucose analog, with the positron-emitting radioactive isotope fluorine-18 substituted for the normal hydroxyl group at the 2′ position in the glucose molecule. Synthesis of the FDG itself is not considered to be part of this invention and only a basic description of a process is included here. Production of 18F-labeled FDG is, by now, well known. Information can be found in: 1) Fowler et al., “2-Deoxy-2-[18F]Fluoro-D-Glucose for Metabolic Studies: Current Status,” Appl. Radiat. Isotopes, vol. 37, no. 8, pp. 663-668 (1986); 2) Hamacher et al., “Efficient Stereospecific Synthesis of No-Carrier-Added 2-[18F]-Fluoro-2-Deoxy-D-Glucose Using Aminopolyether Supported Nucleophilic Substitution,” J. Nucl. Med., vol. 27, pp. 235-238 1986; 3) Coenen et al., “Recommendation for Practical Production of [2-18F]Fluoro-2-Deoxy-D-Glucose,” Appl. Radiat. Isotopes, vol. 38, no. 8, pp. 605-610 (1987) (a good review); 4) Knust et al., “Synthesis of 18F-2-deoxy-2-fluoro-D-glucose and 18F-3-deoxy-3-fluoro-D-glucose with no-carrier-added 18F-fluoride,” J. Radioanal. Nucl. Chem., vol. 132, no. 1, pp. 85-91 (1989); and 5) Hamacher et al., “Computer-aided Synthesis (CAS) of No-carrier-added 2-[18F]Fluoro-2-Deoxy-D-Glucose: An Efficient Automated System for the Aminopolyether-supported Nucleophilic Fluorination,” Appl. Radiat. Isotopes, vol. 41, no. 1, pp. 49-55 (1990). See also U.S. Pat. No. 6,567,492 to Kislelev al. (20 May 2003). Several automatic processing systems capable of production of radiopharmaceuticals, such as 18F-labeled FDG, have also been described in: 1) U.S. Pat. No. 5,808,020 to Ferrieri et al. (15 Sep. 1998); 2) U.S. Pat. No. 6,599,484 to Zigler et al. (29 Jul. 2003); PCT pub. WO2004093652 by Buchanan et al. (2004 Nov. 4); and 3) German patent DE10320552 to Maeding et al. “Apparatus marking pharmaceutical substances with fluorine isotope, preparatory to positron-emission tomography, locates anion exchanger within measurement chamber” (2004 Nov. 25). Clinical Use of 18F-FDG 18F-FDG, as a glucose analog, is taken up by high-glucose-using cells such as brain, kidney, and cancer cells, where phosphorylation prevents the glucose from being released again from the cell, once it has been absorbed. The 2′ hydroxyl group (—OH) in normal glucose is needed for further glycolysis (metabolism of glucose by splitting it), but 18F-FDG is missing this 2′ hydroxyl. Thus, in common with its sister molecule 2-deoxy-D-glucose, FDG cannot be further metabolized in cells. The 18F-FDG-6-phosphate formed when 18F-FDG enters the cell thus cannot move out of the cell before radioactive decay. As a result, the distribution of 18F-FDG is a good reflection of the distribution of glucose uptake and phosphorylation by cells in the body. After 18F-FDG decays radioactively, however, its 2′-fluorine is converted to 18O−, and after picking up a proton H+ from a hydronium ion in its aqueous environment, the molecule becomes glucose-6-phosphate labeled with harmless nonradioactive “heavy oxygen” in the hydroxyl at the 2′ position. The new presence of a 2′ hydroxyl now allows it to be metabolized normally in the same way as ordinary glucose, producing non-radioactive end-products. After 18F-FDG is injected into a patient, a PET scanner can form images of the distribution of FDG around the body. The images can be assessed by a nuclear medicine physician or radiologist to provide diagnoses of various medical conditions. In PET imaging, 18F-FDG can be used for the assessment of glucose metabolism in the heart, lungs, and the brain. It is also used for imaging tumors in oncology, where a static 18F-FDG PET scan is performed and the tumor 18F-FDG uptake is analyzed in terms of Standardized Uptake Value (SUV). 18F-FDG is taken up by cells, phosphorylated by hexokinase (whose mitochondrial form is greatly elevated in rapidly growing malignant tumours), and retained by tissues with high metabolic activity, such as most types of malignant tumours. As a result FDG-PET can be used for diagnosis, staging, and monitoring treatment of cancers, particularly in Hodgkin's disease, colorectal cancer, breast cancer, melanoma, lung cancer, and Alzheimer's disease. Cryptands Cryptands and other macrocyclic compounds such as crown ethers, spherands, cryptahemispherands, cavitands, calixarenes, resorcinorenes, cyclodextrines, porphyrines and others are well known. (Comprehensive Supramolecular Chemistry Vol. 1-10, Jean-Marie Lehn—Chairman of the Editorial Board, 1996 Elsevier Science Ltd.) Many of them are capable of forming stable complexes with ionic organic and inorganic molecules. Those properties make macrocyclic compounds candidates for various fields, for instance, catalysis, separations, sensors development and others. Cryptands (bicyclic macrocycles) have extremely high affinity to metal ions. The cryptand metal ion complexes are more stable than those formed by monocyclic ligands such as crown ethers (Izatt, R. M., et al., Chemical Reviews 91:1721-2085 (1991)). This high affinity of the cryptands to alkaline and alkaline earth metal ions in water makes them superior complexing agents for the processes where strong, fast and reversible metal ion binding is required. Examples of these processes include separation, preconcentration and detection of metal ions, analysis of radioactive isotopes, ion-exchange chromatography, phase-transfer catalysis, activation of anionic species and others. Many strategies for the synthesis of macrocyclic compounds have been developed over the years (Comprehensive Supramolecular Chemistry Vol. 1-10, Jean-Marie Lehn—Chairman of the Editorial Board, 1996 Elsevier Science Ltd.; Krakowiak, K. E., et al., Israel Journal of Chemistry 32:3-13 (1992); Bradshaw, J S., et al., “Aza-Crown Macrocycles,” The Chemistry of Heterocyclic Compounds, Vol. 51, ed. Taylor, E. C., Wiley, New York, 1993; Haoyun, A., et al., Chemical Reviews 92:543-572 (1992)). The Cryptands may be synthesised as described in US20040267009 A1, Bernard Dietrich, Jean-Marie Lehn, Jean Guilhem and Claudine Pascard, Tetrehedron Letters, 1989, Vol. 30, No. 31, pp 4125-4128, Paul H. Smith et al, J. Org. Chem., 1993, 58, 7939-7941, Jonathan W. Steed et al, 2004, Journal of the American Chemical Society, 126, 12395-12402, Bing-guang Zhang et al, Chem. Comm., 2004, 2206-2207. Cryptands are cavity containing macromolecules which form stable complexes with alkali metal ions. For a given cation, the stability constant is largest for the cation which fits best into the cavity of the ligand. Thus stability maxima are found for Li[2.1.1]+, Na[2.2.1]+, and K[2.2.2]+ (Cox, B. G. Effects of substituents on the stability and kinetics of alkali metal cryptates in methanol. Inorganica Chimica Acta, 1981, 49, 153-158). In one embodiment of the present invention novel [18F]fluoride diaryl- and aryl-fused [2.2.2]cryptate complexes suitable for radiolabeling fluorinations. A further embodiment of the method in the present invention is wherein the di-substitutent in the di-substituted [2.2.2] cryptand is diaryl. Yet another embodiment of the invention is wherein the di-substituent in the disubstituted [2.2.2] cryptand is dibenzo. Yet another embodiment of the invention is wherein the di-substituent in the disubstituted [2.2.2] cryptand is dinaphtho. Yet, in a further embodiment of the present method the [18F] fluoride-complex is used to radiolabel a [18F] fluorinated species wherein the radiolabelled [18F] fluorinated species is used as an imaging agent in a patient. Still another embodiment of the present invention discloses the imaging agent as being viewed within a patient by an imaging technique such as a positron emission tomography (“PET”) scanner. The effect of substituents on macrocyclic molecules was first observed by Pedersen (Pedersen, C. J. J. Am. Chem. Soc. 1967, 89, 7017). Subsequently, many different moieties have been introduced into the macrocyclic backbone to modify the properties of the hosts, e.g., to increase rigidity and lipophilicity, (Marchand, A. P.; Huang, Z.; Chen, Z.; Hariprakasha, H. K.; Namboothiri, I. N. N.; Brodbelt, J. S.; Reyzer, M. L. J. Heterocyclic Chem. 2001, 38, 1361). The effect of increased rigidity introduced by the incorporated moiety can be interpreted in terms of preorganization. The principle of preorganization (Cram, D. J. in From Design to Discovery American Chemical Society, Washington D.C., 1991, p 9) states: “The more highly hosts and guests are organized for binding and low solvation prior to complexation, the more stable will be the complexes. The topology, along with ring size determines the degree of preorganization of a specific structure for complexation. The general trend is that the two-dimensional structure develops into a three dimensional structure, wherein, for similar ring-size, the rigidity of the molecule increases. For example, rigidity increases along the series 18-crown-6, [2.2.2]-cryptand. Increasing rigidity in this way restricts the ability of the ligand to undergo conformational reorganization. Thus more rigid ligands are more highly “preorganized”. Since the host must undergo conformational adjustment to provide a proper binding environment during the host-guest interaction. Thus, preorganization of a ligand, which is associated with its topology, rigidity and solvation, becomes important. For a specific guest, the more highly preorganized ligand requires less conformational change and thus pays minimal energy cost for conformational adjustment. Increasing rigidity of the host the more highly preorganized host and the more highly host and guest are organized for binding the more stable the complexes will be. In order to attain high, yet selective binding of a potassium ion chelator some rigidity in the system such as the ionophore “dibenzo-[2.2.2] cryptand” was considered necessary. The cavity size of [2.2.2] cryptand (2.8 A° in diameter) closely matches the size of potassium cation (2.66 A°). Substituted [2.2.2] cryptands, such as dibenzo [2.2.2] cryptand, possess a guest binding site (ionophore) having heteroatom with nonbonding electron pairs such as nitrogen, capable of binding potassium (K+) selectively in its cavity. The synthesis of dibenzo-cryptand [2.2.2]; namely 4,7,13,16,20,23-hexaoxa-1,10-diaza-19(1,2),24(1,2)-dibenzabicyclo[8.8.6]tetracosaphane (VII) is outlined in Scheme 1. The commercially available 2-nitrophenol (I) was chosen as a starting material. Treatment of two equivalents of (I) with 1,2-dibromoethane and potassium carbonate in dimethyl formamide (DMF) afforded 1,2-Bis (2-nitrophenoxy)ethane (II). Reduction of (II) with 10% Palladium-on-charcoal as the catalyst produced the amino derivative (III). The diamine (III) was reacted with 3,6-dioxaoctanedioyl dichloride (1,2-ethylene-O,O-diglycolic acid chloride) in tetrahydrofuran (THF) at high dilution conditions in tetrahydrofuran (Dietrich, B.; Lehn, J. M.; Sauvage, J. P.; Blanzat, J. Cryptates. X. Syntheses and physical properties of diazapolyoxamacrobicyclic systems. Tetrahedron 1973, 29, 1629) to give the lactam (IV). The lactam (IV) was reduced with Lithium Aluminum Hydride (LiAlH4) in THF to give the azacrown (V) (Previously reported by de Silva, A. P.; Gunaratne, H. Q. N.; Samankumura, K. R. A. S. A new benzo-annelated cryptand and a derivative with alkali cation-sensitive fluorescence. Tetrahedron Lett. 1990, 31, 5193-5196). Subsequent treatment of (V) with 3,6-dioxaoctanedioyl dichloride gave (VI) which upon reduction with diborane in tetrahydrofuran (Pettit, W. A.; Iwai, Y.; Berfknecht, C. F.; Swenson, D. C. Synthesis and structure of N1-e-benzo-4,7,13,16,21,26-hexaoxa-1,10-diazabicyclo[8.8.8]hexacos-23-yl-N2-phenylthiourea. Derivative of a bifunctional complexing agent. J. Heterocycl. Chem 1992, 29, 877) furnished the cryptand (VII). The phenyl groups of cryptand VII can be further derivatized by further chemical reactions such as bromination. Bromination of (VII) with 2,4,4,6-tetrabromo-2,5-cyclohexadien-1-one afforded the dibromo-cryptand (VIII). The dibromo-cryptand (VIII) was also prepared by an alternative reaction sequence starting with azacrown (V). Bromination of (V) with bromine afforded both monobromo azacrown (IX) and dibromo azacrown (X). Treatment of (X) with 3,6-dioxaoctanedioyl dichloride afforded (XI) which upon reduction with Borane in THF gave the dibromo-cryptand (VIII). (Naguib, Y M A. Molecules 2009, 14, 3600-3609). Di-substituted [2.2.2] cryptand possesses a guest binding site (ionophore) having heteroatom with nonbonding electron pairs such as nitrogen, capable of binding potassium (K+) selectively in its cavity. Cryptand is a phase-transfer agent used to complex [18F] fluoride in non-aqueous environment to form [18F] fluoride cryptate complexes suitable for performing radio-labeling reactions to generate [18F] fluorinated species to be viewed through an imaging agent such as Positron Emmision Tomography (“PET”) and that a [18F] fluorinated species defined herein comprises chemical or biological [18F] fluorinated compounds for use as imaging agents. Several approaches for incorporating 18F in biomolecules are described in the following references: Kuhnast, B., et al. (2004) J. Am. Chem. Soc., 15, 617-627; Garg, P. K., et al. (1991) Bioconj. Chem., 2, 44-49; Lee, B. C., et al. (2004) J. Am. Chem. Soc., 15, 104-111; Chen, X., et al. (2004) J. Am. Chem. Soc., 15, 41-49; Glaser, M., et al. (2004) J. Am. Chem. Soc., 15, 1447-1453; Toyokuni et al. Bioconjug. Chem. (2003) 14: 1253-9; and Couturier, O., et al. (2004) Eur. J. of Nuc. Med. and Mol. Imaging, 31, 1182-1206). The present invention is not to be limited in scope by specific to embodiments described herein. Indeed, various modifications of the inventions in addition to those described herein will become apparent to those skilled in the art from the foregoing description. Such modifications are intended to fall within the scope of the appended claims. Various publications and patent applications are cited herein, the disclosures of which are incorporated by reference in their entireties. Jewett et al, “Multiphase Extraction: Rapid Phase-Transfer of [18F]Fluoride Ion for Nucleophilic Radiolabeling Reactions,” Appl. Radiat. Isot., vol. 39, No. 11, pp. 1109-1111, 1988 No-Carrier-Added (NCA) ARYL [18F] Fluorides Via the Nucleophilic Aromatic Substitution of Electron-Rich Aromatic Rings,” Ding et al. Journal of Fluorine Chemistry vol. 48, pp. 189-205 (1990) The Synthesis of 6-[18] Fluoro-L-Dopa by Chiral Catalytic Phase-Transfer Alkylation,” C. Lemaire et al., J. Label Labelled Cpd., Radiopharm 42 (1999) S113-S115 F-18 labeled biomolecules for PET studies in the neurosciences, Ding Y S, Journal of Fluorine Chemistry, 101: (2) 291-295 February 2000 Proton Irradiation of [180]02: Production of [18F]F2 and [18F]F2+[18F]OF2, Allyson Bishop et al., Nuclear Med. Biol. 1996, 23, 189-199 4-[18F]Fluoroarylalkylethers via an improved synthesis of n.c.a. 4-[18F]fluorophenol,” T. Ludwig et al., Nuclear Medicine and Biology 29 (2002) 255-262 Babb, D. A., et al., “Synthesis of Hydroxymethyl-Functionalized-Diazacrowns and Cryptands,” Journal of Heterocyclic Chemistry 23:609-613 (1986) Blasius, E., et al., “Preparation and Application of Polymers with Cyclic Polyether Anchor Groups,” Pure & App. Chem. 54(11):2115-2128 (1982) Bradshaw, J. S., et at, “Stable Silica Gel-Bound Crown Ethers. Selective Separation of Metal Ions and a Potential for Separations of Amine Enantiomers,” Journal of Inclusion Phenomena and Molecular Recognition in Chemistry 7:127-136 (1989) Bradshaw, J. S., et al., “Silical gen-bound aza-crowns for the selective removal and concentration of metal ions,” Pure & Appl. Chem. 61:1619-1624 (1989) Krakowiak, K. E., et al., “Syntheses of the Cryptands. A Short Review,” Israel Journal of Chemistry 32:3-13 (1992) Krakowiak, K. E., et al., “One-step Methods to Prepare Cryptands and Crowns Containing Reactive Functional Groups,” Journal of Heterocyclic Chemistry 27:1011-1014 (1990) Krespan, C. G., “Functionalized Macroheterobicyclic Compounds,” Journal of Organic Chemistry 45:1177-1180 (1980) Montanari, F., et al., “Hydroxymethyl Derivatives of 18-Crown-6 and [2.2.2]Cryptand: Versatile Intermediates for the Synthesis of Lipophilic and Polymer-Bonded Macrocyclic Ligands,”, J. Org. Chem., 47:1298-1302 (1982) Dietrich, B., “Cryptands,” in Comprehensive Supramolecular Chemistry, Atwood et al. eds., Jean-Marie Lehn—Chairman of the Editorial Board, New York: Pergamon, 1996, vol. 1, G. W. Gokel, ed., pp. 154-157, 186, 192
	abstract	The radiography apparatus of the present invention includes a CPU 71 having a function of a lighting time limitation means to control the lighting time of light sources in such a way as to maintain a temperature at or below a predetermined temperature. In order to discriminate the type of light source connected to the device body, the setting of No. 5 pin on the CPU 71 to a high logic state or a low logic state is detected. This enables the detection of whether the light source connected to a control board 70 is a halogen lamp H or a light emitting diode (LED) L. Thus, the type of the light source is discriminated. The CPU 71 changes the controlled limiting lighting time based on the result of discrimination. This prevents the risk of incorrectly carrying out settings and enables the automatic setting for switching light sources.
	description	This application is a divisional of U.S. application Ser. No. 12/441,919 filed Mar. 19, 2009, which is National Stage Entry of PCT/US2007/021344 filed Oct. 3, 2007, which claims priority from U.S. Provisional Application No. 60/849,869, filed Oct. 6, 2006, all of which are incorporated herein by reference. The invention relates generally to radioisotope elution systems and, more specifically, to self-aligning components for use in such systems. This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present invention, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art. Nuclear medicine uses radioactive material for diagnostic and therapeutic purposes by injecting a patient with a dose of the radioactive material, which concentrates in certain organs or biological regions of the patient. Radioactive materials typically used for nuclear medicine include Technetium-99m, Indium-111, and Thallium-201 among others. Some chemical forms of radioactive materials naturally concentrate in a particular tissue, for example, iodide (I-131) concentrates in the thyroid. Radioactive materials are often combined with a tagging or organ-seeking agent, which targets the radioactive material for the desired organ or biologic region of the patient. These radioactive materials alone or in combination with a tagging agent are typically referred to as radiopharmaceuticals in the field of nuclear medicine. At relatively low doses of the radiopharmaceutical, a radiation imaging system (e.g., a gamma camera) may be utilized to provide an image of the organ or biological region that collects the radiopharmaceutical. Irregularities in the image are often indicative of a pathology, such as cancer. Higher doses of the radiopharmaceutical may be used to deliver a therapeutic dose of radiation directly to the pathologic tissue, such as cancer cells. A variety of systems are used to generate, enclose, transport, dispense, and administer radiopharmaceuticals. Using these systems often involves manual alignment of components, such as male and female connectors of containers. Unfortunately, the male connectors can be damaged due to misalignment with the corresponding female connectors. For example, hollow needles can be bent, crushed, or broken due to misalignment with female connectors. As a result, the systems operate less effectively or become completely useless. If the systems contain radiopharmaceuticals, then the damaged connectors can result in monetary losses or delays with respect to nuclear medicine procedures. Certain exemplary aspects of the invention are set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of certain forms the invention might take and that these aspects are not intended to limit the scope of the invention. Indeed, the invention may encompass a variety of aspects that may not be set forth below. In some embodiments of the present invention, a radioisotope elution system includes self-aligning components that protect needles from being damaged. In one embodiment, a radioisotope generator includes an alignment structure that is keyed to a complementary alignment structure on a lid of an auxiliary radiation shield. The complementary alignment structure may be inserted into the alignment structure, and the position of the lid relative to the radioisotope generator may be generally fixed. Once these components are aligned, apertures in the lid may be used to guide various components onto the needles of the generator in a controlled manner, thereby reducing the likelihood of a misaligned component damaging the needles. A first aspect of the present invention is directed to a radioisotope elution system that includes a radioisotope generator having an alignment structure configured to interface with a complementary alignment structure on a radiation shield. A second aspect of the invention is directed to a radiation shield for shielding a radioisotope generator. The radiation shield has a shield lid that includes an alignment structure configured to align the shield lid to a radioisotope generator. A third aspect of the invention is directed to radioisotope elution system that includes an auxiliary shield having a top plane, a shield lid that includes a handle, and a radioisotope generator disposed in the auxiliary shield and biased by the weight of the shield lid. The shield lid may be disposed in the auxiliary shield, and the handle may cross the top plane. A fourth aspect of the invention is directed to a method of operating a radioisotope elution system. The method includes aligning a radiation shield lid to a radioisotope generator via a first alignment structure on the radiation shield lid and a second alignment structure on the radioisotope generator. Various refinements exist of the features noted above in relation to the various aspects of the present invention. Further features may also be incorporated in these various aspects as well. These refinements and additional features may exist individually or in any combination. For instance, various features discussed below in relation to one or more of the illustrated embodiments may be incorporated into any of the above-described aspects of the present invention alone or in any combination. Again, the brief summary presented above is intended only to familiarize the reader with certain aspects and contexts of the present invention without limitation to the claimed subject matter. One or more specific embodiments of the present invention will be described below. In an effort to provide a concise description of these embodiments, all features of an actual implementation may not be described in the specification. It should be appreciated that in the development of any such actual implementation, as in any engineering or design project, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which may vary from one implementation to another. Moreover, it should be appreciated that such a development effort might be complex and time consuming, but would nevertheless be a routine undertaking of design, fabrication, and manufacture for those of ordinary skill having the benefit of this disclosure. When introducing elements of various embodiments of the present invention, the articles “a”, “an”, “the”, and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including”, and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. Moreover, the use of “top”, “bottom”, “above”, “below” and variations of these terms is made for convenience, but does not require any particular orientation of the components. As used herein, the term “coupled” refers to the condition of being directly or indirectly connected or in contact. FIG. 1 shows an exemplary radioisotope elution system 10 that includes an auxiliary shield assembly 12, an elution tool 14, and an eluant assembly 16. As discussed below, a variety of alignment structures, alignment mechanisms, and/or alignment indicators may be incorporated into the radioisotope elution system 10 to facilitate proper alignment of the various containers, hollow needles, radioisotope generator, and other components residing inside the auxiliary shield assembly 12. The illustrated auxiliary shield assembly 12 includes an auxiliary shield lid 18 and an auxiliary shield 20. For brevity, the auxiliary shield lid 18 is referred to as a “lid.” The auxiliary shield 20 may include a top ring 22, a base 24, and a plurality of step-shaped or generally tiered modular rings 26, which are disposed one over the other between the base 24 and the top ring 22 (see FIGS. 1 and 7). Substantially all or part of the illustrated auxiliary shield assembly 12 may be made of one or more suitable radiation shielding materials, such as depleted uranium, tungsten, tungsten impregnated plastic, or lead. One or more of the components of the auxiliary shield assembly 12 may be lined with, powder coated on, and/or embedded in other materials, such as an appropriate polymer material. For instance, in some embodiments, at least a portion (e.g., a majority, or a substantial entirety) of the lid 18 of the assembly 12 may be over-molded with polycarbonate resin (or other appropriate polymer). Embedding or over-molding the shielding materials may promote safety, enhance durability, and/or facilitate formation of components with smaller dimensional tolerances than components made entirely out of shielding materials. Moreover, the modular aspect of the rings 24 may tend to enhance adjustment of the height of the auxiliary shield 12, and the step-shaped configuration may tend to contain some radiation that might otherwise escape through an interface between the modular rings 26. While FIG. 1 depicts one example of an auxiliary shield assembly 12, it should be noted that other auxiliary shield assemblies may be employed. FIGS. 2, 3 are exploded views of the radioisotope elution system 10 from different perspectives. The auxiliary shield assembly 12 is designed to house a radioisotope generator 28 within the auxiliary shield 20 and under the lid 18. The radioisotope generator 28 may include a generator body 30, a needle assembly 32, and a cap 34. The illustrated generator body 30 includes an elution column configured to generate and output a desired radioisotope. Except for the needle assembly 32, the various components of the elution column of the radioisotope generator 28 are not shown in detail. However, elution columns are well known to those of ordinary skill in the art (see U.S. Pat. No. 5,109,160 and U.S. Patent Application Publication No. 2005/0253085, for example). As such, one of ordinary skill in the art could easily employ various aspects of the invention with radioisotope generators having a wide range of elution column designs. Certain medically useful radioisotopes have relatively short half-lives (e.g., technetium-99m (Tc99m) has a half-life of approximately 6 hours). To potentially expand the useful life of the radioisotope generator 28, the elution column may include a more stable radioisotope that decays into the desired radioisotope (e.g., molybdenum-99 (Mo99) has a half-life of approximately 66 hours and decays into Tc99m). As the desired radioisotope is needed, it may be separated from the more stable radioisotope with an elution process, as explained below. The generator body 30 may also include shielding configured to diminish radiation, and tubing to conduct fluids into and out of the elution column. Externally, the illustrated generator body 30 includes a lifting strap 36, two strap supports 38, 40, and outer rings 42, 44. The two strap supports 38, 40 extend upward from the generator body 30 and pivotably interconnect (e.g., connect in a manner that enables pivoting or pivot-like motion (e.g., flexing, elastic deformation, etc.)) to opposing ends of the lifting strap 36. The outer rings 42, 44 are near the top and bottom of the generator body 30, respectively. As depicted in FIG. 7, the outer rings 42, 44 extend radially from the generator body and limit the range of non-axial movement (e.g., movement other than up or down translation) of the generator body 30 within the auxiliary shield 20. The needle assembly 32 may include an input needle 46, an output needle 48, and a vent needle 50. The tubing in the generator body 30 may fluidly interconnect (e.g., connect either directly or indirectly in a manner that enables fluid to flow there between) to needles 46, 48, and/or 50. Specifically, the input needle 46 may fluidly interconnect with an input to the elution column, and the output needle 48 may fluidly interconnect with an output from the elution column. The vent needle 40 may vent to atmosphere to equalize pressure during an elution, as explained below. The needles 46, 48, 50 are hollow to facilitate fluid flow therein. The cap 34 may include needle apertures 52, 54, support channels 56, 58, tabs 60, 62, 64, 66, a top surface 67, and an alignment structure 68. Here, the term “alignment structure” refers to a member or surface that reduces the range of relative motion between two components as those components are interconnected, coupled, or brought into proximity. In other words, an alignment structure reduces the number of degrees of freedom between components as the components are interfaced (e.g., brought into contact with each other or an intermediary component such that mechanical forces may be transmitted from one alignment structure to another). The needle apertures 52, 54 are disposed within the alignment structure 68. In other embodiments, the needle apertures 52, 54 may be positioned elsewhere relative to the alignment structure 68, e.g., not within it or on a separate component. The support channels 56, 58 are shaped to complement the strap supports 38, 40 and orient the cap 34 relative to the generator body 30. That is, the support channels 56, 58 cooperate with the strap supports 38, 40 to align the cap 34 to the generator body 30 in one of a finite number of discrete orientations and positions, such as a single orientation and position. The illustrated alignment structure 68 generally defines a cylinder with an oval base 70 and walls 72 that are generally perpendicular to the base 70. As used herein, the term “cylinder” refers to a surface or solid bounded by two parallel planes and generated by a straight line (i.e., a generatrix) moving parallel to the given planes and tracing a curve (including but not limited to a circle) bounded by the planes and lying in a plane perpendicular or oblique to be given planes. The base 70 is generally parallel to the base 24 of the auxiliary shield 20, and the cylinder defined by the alignment structure 68 has a single plane of symmetry that is generally perpendicular to the base 70. The illustrated alignment structure 68 is recessed in word into the cap 34 and maybe generally characterized as a female alignment structure. In other embodiments, the alignment structure 68 may have a variety of different shapes and configurations. For example, the alignment structure 68 may be generally asymmetric, or the alignment structure 68 may extend outward from the cap 34. As described below, the alignment structure 68 may align the lid 18 to the radioisotope generator 28. FIG. 4 depicts the radioisotope generator 28 in an assembled state. The needle assembly 32 is disposed between the cap 34 and the generator body 32. The needles 46, 48, 50 extend through the apertures 52, 54, and the tabs 60, 62, 64, 66 are inserted into the generator body 32. Additionally, the strap supports 38, 40 are aligned with and inserted in the support channels 56, 58, respectively, thereby generally fixing the position and orientation of the cap 34 relative to the generator body 30. With reference to FIGS. 2, 3, and 5, the lid 18 will now be described. In the present embodiment, the lid 18 includes a bottom surface 74, a complementary alignment structure 76, a sidewall 78, handles 80, 82, an elution tool aperture 84, and an eluant aperture 86. The lid 18 may be made of appropriate radiation shielding materials, such as those discussed above. The handles maybe generally U-shaped. The illustrated complementary alignment structure 76, which may be generally characterized as a male alignment structure, extends downward from the bottom surface 74 and includes a mating surface 88 that is generally perpendicular to the bottom surface 74. The complementary alignment structure 76 generally defines a right cylinder (e.g., a cylinder with sidewalls that are perpendicular to the base) with an oval base that is complementary (e.g., keyed) to the alignment structure 68. In other words, the complementary alignment structure 76 is configured to mate with the alignment structure 68 on the radioisotope generator 30. When the alignment structures 76, 68 are mated, the sidewall 72 may be in contact with or proximate to the mating surface 88 on the lid 18, and contact between the surfaces may reduce the number of degrees of relative freedom between these components. In short, the alignment structures 76, 78 may cooperate to align the lid 18 with the radioisotope generator 30. The elution tool aperture 84 and eluant aperture 86 extend through the illustrated lid 18. These apertures 84, 86 may have a generally circular horizontal cross-section that is generally constant through at least a portion of the vertical thickness of the lid 18. The apertures 84, 86 may be disposed within and extend through the complementary alignment structure 76. In other embodiments, these features 84, 86, 76 may be disposed else elsewhere with respect to one another. The eluant aperture 86 may include a flared portion 90 (see FIGS. 3 and 6) for positioning subsequently discussed components. Referring general to FIGS. 2 and 3, the elution tool 14 may have a generally cylindrical shape and include an outer shield 92 and an eluate receptacle 94. The outer shield 92 is made of radiation shielding material, such as those discussed above, and is shaped to be inserted through the elution tool aperture 84 on the lid 18. During insertion, contact between the outer shield 92 and the elution tool aperture 84 may generally confine the elution tool 14 to translating up and down and substantially prevent the elution tool 14 from translating horizontally or rotating about a horizontal axis (e.g., rotating end-over-end). In other words, the elution tool aperture 84 may cooperate with the outer shield 92 to position the elution tool 14 over the input needle 48 and guide the elution tool 14 along a path that is generally parallel (e.g., coaxially) with the input needle 48, thereby generally preventing the elution tool 14 from potentially damaging the input needle 48. The eluate receptacle 94 may be generally enveloped by the outer shield 92 with the exception of an aperture 96 in the bottom of the outer shield 92. The eluate receptacle 94 may include an evacuated vial, a conduit, or some other container configured to receive fluid from the output needle 48 on the radioisotope generator 28. The eluant assembly 16 may include an eluant shield 98 and an eluant source 100. The illustrated eluant shield 98 has a handle 102, guide members 104, 106, and a recessed portion 108. The eluant shield 98 may be made of radiation shielding material, such as those materials discussed above. The guide members 104, 106 are shaped to fit within the flared portion 90 of the lid 18 and guide the eluant shield 98 into a resting position on the lid 18 (see FIG. 1). The recessed portion 108 generally corresponds to the shape of the top of the eluant source 100, which may be a vial of saline or other appropriate fluid. The eluant source 100 has a generally cylindrical shape and is sized such that it may pass through the eluant aperture 86 in the lid 18. When the eluant source 100 is inserted through the eluant aperture 86, contact with the walls of the eluant aperture 86 many generally constrain movement of the eluant source to up-and-down translation and rotation about a vertical axis. In other words, this contact may tend to prevent the eluant source 100 from translating horizontally or rotating about a horizontal axis during insertion. That is, the position and orientation of the eluant aperture 86 generally determines the position and orientation of the eluant source 100 when the eluant source 100 is positioned therein. FIGS. 6, 7 depict top and cross-section views, respectively, of the assembled radioisotope elution system 10. The radioisotope generator 28 is positioned within a cylindrical receptacle 108 in the auxiliary shield 20, and the top surface 67 of the cap 34 recessed below a top plane 110 of the auxiliary shield 20. Contact between the outer rings 42, 44 and the walls of the cylindrical receptacle 108 may tend to reduce horizontal translation of the radioisotope generator 28 and rotation of the radioisotope generator 28 about horizontal axes (e.g., rotating end-over-end). The lid 18 also fits into the cylindrical receptacle 108, and the shape of the outer walls 78 generally corresponding to the shape of the side walls of the cylindrical receptacle 108. Contact between the sidewalls 78 and the sidewalls of the cylindrical receptacle 108 may tend to reduce horizontal translation of the lid 18 and rotation of the lid 18 about horizontal axes. The lid 18 may be generally free to slide vertically within the cylindrical receptacle 108 until the bottom surface 74 of the lid 18 makes contact with the top surface 67 of the cap 34. In other words, the lid 18 may rest on the radioisotope generator 28 with the radioisotope generator 28 carrying the weight of the lid 18. A variety of components may interface with the lid 18. As discussed above, the eluant source 100 may slide through the eluant aperture 86 in the lid 18, and contact between these components 86, 100 may tend to reduce horizontal translation of the eluant source 100 and rotation of the eluant source 100 about horizontal axes. Similarly, the elution tool 14 may slide through the elution tool aperture 84, and contact between these components 14, 84 may tend to reduce horizontal translation of the elution tool 14 and rotation of the elution tool 14 about horizontal axes. In other words, the lid 18 may tend to constrain movement of the elution tool 14 and eluant source 100 to an up-and-down motion that is parallel (e.g., coaxial) with the needles 46, 48, 50 as these components 14, 100 are brought in contact with the needles 46, 48, 50. Aligning the elution tool 14 and eluant source 100 with the needles 46, 48, 50 before they make contact may reduce the chances of the needles 46, 48, 50 being damaged. The eluant shield 98 may rest on the lid 18 and cover a portion of the eluant source 100 that extends above a top of the lid 18. In the assembled state depicted by FIGS. 6, 7, the lid 18 is aligned to the radioisotope generator 28. The complementary alignment structure 76 on the lid 18 is inserted into the alignment structure 68 on the cap 34. Contact between the sidewalls 88 of the complementary alignment structure 76 and the sidewalls 72 of the alignment structure 68 may tend to reduce rotation of the lid 18 about vertical axes and reduce horizontal translation of the lid 18. In other words, when assembled, the lid 18 and radioisotope generator 28 generally have a single degree of freedom, i.e., vertical translation of the lid 18 in the cylindrical receptacle 108 away from the radioisotope generator 28. Other embodiments may include a latch or locking device for the lid 18 and reduce the number of degrees of freedom to zero. In operation, an eluant inside the eluant source 100 is circulated through the inlet needle 46, through the radioisotope generator 28 (including the elution column), and out through the outlet needle 48 into the eluate receptacle 94. This circulation of the eluant washes out or generally extracts a radioactive material, e.g., a radioisotope, from the radioisotope generator 28 into the eluate receptacle 94. For example, one embodiment of the radioisotope generator 28 includes an internal radiation shield (e.g., lead shell) that encloses a radioactive parent, such as molybdenum-99, affixed to the surface of beads of alumina or a resin exchange column. Inside the radioisotope generator 28, the parent molybdenum-99 transforms, with a half-life of about 66 hours, into metastable technetium-99m. The daughter radioisotope, e.g., technetium-99m, is generally held less tightly than the parent radioisotope, e.g., molybdenum-99, within the radioisotope generator 28. Accordingly, the daughter radioisotope, e.g., technetium-99m, can be extracted or washed out with a suitable eluant, such as an oxidant-free physiologic saline solution. Upon collecting a desired amount (e.g., desired number of doses) of the daughter radioisotope, e.g., technetium-99m, within the eluate receptacle 94, the elution tool 14 can be removed from the radioisotope elution system 10. As discussed in further detail below, the extracted daughter radioisotope can then, if desired, be combined with a tagging agent to facilitate diagnosis or treatment of a patient (e.g., in a nuclear medicine facility). The illustrated radioisotope elution system 10 is a dry elution system. Prior to an elution, the eluant receptacle 94 is substantially evacuated, and the eluant source 100 is filled with a volume of saline that generally corresponds to the desired volume of radioisotope solution. During an elution, the vacuum in the eluant receptacle 94 draws saline from the eluant source 100, through the radioisotope generator 28, and into the eluant receptacle 94. After substantially all of the saline has been drawn from the eluant source 100, a remaining vacuum in the eluant receptacle 94 draws air through the radioisotope generator 28, thereby removing fluid that might otherwise remain in the radioisotope generator 28. Air or other appropriate fluids may flow into the eluant source 100 through the vent needle 50 and into the radioisotope generator 28 through the input needle 46. The volume and pressure of the eluant receptacle 94 may be selected such that substantially all of the eluant fluid is drawn out of the radioisotope generator 28 by the end of an elution operation. In view of the operation of the elution system 10, proper alignment of the various components may be particularly important to the life of the needles 46, 48, 50 and, thus, proper circulation of the eluant from the eluant source 100 through the radioisotope generator 28 and into the eluant receptacle 94. For example, when the eluant source 100 is coupled to the needles 46, 50, it may bend the needles 46, 50 if not properly aligned. Similarly, pressing the elution tool 14 down onto the needle 48 may bend the needle 48 if the elution tool 14 is not properly aligned. Certain embodiments of a subsequently described elution process may align the eluant source 100 with the needles 46, 50 before the eluant source 100 contacts the needles 46, 50 and, also, may align the elution tool 14 with the needle 48 before the elution tool 14 contacts the needle 48. Moreover, certain embodiments may guide the elution tool 14 and the eluant source 100 through an up or down movement that is parallel with the needles 46, 48, 50 when the elution tool 14 and eluant source 100 are positioned over the needles 46, 48, 50 and properly oriented. An elution process 112 will now be described with reference to FIG. 8. Initially, a radiation shield, such as the lid 18, is aligned to a generator, as depicted by block 114. In the embodiment of FIGS. 1-7, aligning a radiation shield includes interfacing the alignment structure 68 on the cap 34 with the complementary alignment structure 76 on the lid 18. The lid 18 is inserted into the cylindrical receptacle 108 in the auxiliary shield 20 and lowered until the lid 18 makes contact with the top surface 67 of the cap 34. Then the lid 18 is rotated about a vertical axis within the cylindrical receptacle 108 until the complementary alignment structure 76 slides into the alignment structure 68. The complementary alignment structure 76 is inserted into the alignment structure 68 until the bottom surface 74 of the lid 18 makes contact with the top surface 67 of the cap 34. At this point, the position and orientation of the lid 18 is generally determined by the position and orientation of the radioisotope generator 28. In other words, the lid 18 is referenced to the radioisotope generator 28. Once aligned, in some embodiments, lid 18 and radioisotope generator 28 may have a single degree of relative freedom: for example, the lid 18 may translate vertically within the cylindrical receptacle 108, but the lid 18 may be generally obstructed from rotating about horizontal or vertical axes or translating horizontally. Because the lid 18 can translate vertically within the cylindrical receptacle 108, the radioisotope elution system 10 may accommodate radioisotope generators 28 of a variety of sizes. In other words, the lid 18 is able to self-adjust the height to match the generator 28. For example, the lid 18 may translate further into the cylindrical receptacle 108 to accommodate a smaller radioisotope generator 28 or less distance to accommodate a larger radioisotope generator 28. After aligning the radiation shield to the generator, a source of eluant may be aligned to the radiation shield, as depicted by block 116. For example, the eluant source 100 may be aligned to the lid 18. Aligning the eluant source 100 may include vertically orienting eluant source 100 over the eluant aperture 86 and inserting the eluant source 100 through the eluant aperture 86 until the needles 46, 50 have substantially penetrated the eluant source 100. Because the lid 18 is aligned (or referenced) to the radioisotope generator 28 and the eluant source 100 is aligned (or referenced) to the lid 18, the eluant source 100 may be aligned (or referenced) to the radioisotope generator 28. Moreover, the path traveled by the eluant source 100 as it interfaces or makes contact with the needles 46, 50 may be controlled by the eluant aperture 86. That is, the eluant aperture 86 may guide the eluant source 100 onto the needles 46, 50 in a path that is substantially parallel to the needles 46, 50. Next an elution tool is aligned to the radiation shield, as depicted by block 118. In the embodiment of FIGS. 1-7, the elution tool 14 may be aligned with the elution aperture 84 on the lid 18. Aligning the elution tool 14 may include positioning the elution tool 14 over the elution aperture 84 and vertically orienting the elution tool 14 so that it may be inserted into the elution aperture 84. As the elution tool 14 is inserted, the elution receptacle 94 may vertically translate in a direction that is parallel with the needle 48. That is the eluant aperture 84 may guide the elution tool 14 onto the needle 48 in a path and orientation that are referenced to the needle 48. During insertion, movement of the elution tool 14 relative to the needle 48 and radioisotope generator 28 may be generally limited to vertical translation and rotation about a vertical axis. FIG. 9 depicts another radioisotope elution system 120. The embodiment of FIG. 9 includes a T-shaped handle 122 that extends upward from the lid 18 and through the top plane 110 of the auxiliary shield 20. The present embodiment includes a pair of T-shaped handles 122 symmetrically dispose on the lid 18. Other embodiments may include handles with different shapes and/or handles that do not extend above the top plane 110. FIG. 10 depicts a radioisotope elution system 124 that is configured to indirectly align the lid 18 with the radioisotope generator 28. In the present embodiment, the lid 18 includes alignment structures 126, 128, and the radioisotope generator 28 includes alignment structure 130, 132. The auxiliary shield 20 includes complementary alignment structures 134, 136, 138, 140, which mate with (or are keyed to) the alignment structures 128, 126, 130, 132. Specifically, the triangle-shaped alignment structures 128, 126 on the lid 18 interface with the complementary alignment structures 136, 140 to align the lid 18 to the auxiliary shield 22. Similarly, the square-shaped alignment structures 130, 132 interface with the complementary alignment structures 134, 138 to align the radioisotope generator 28 to the auxiliary shield 22. That is, both the radioisotope generator 28 and the lid 18 are aligned to the auxiliary shield 22, thereby aligning these components 18, 28 with each other. In other words, the lid 18 is indirectly aligned with the radioisotope generator 28 through the auxiliary shield 22. Other embodiments may include alignment structures with different shapes, different positions, and/or other intermediary components. FIG. 11 is a flowchart illustrating an exemplary nuclear medicine process that uses the radioactive isotope produced by the previously discussed radioisotope elution systems 10, 110, 124. As illustrated, the process 162 begins by providing a radioactive isotope for nuclear medicine at block 164. For example, block 164 may include eluting technetium-99m from the radioisotope generator 22 illustrated and described in detail above. At block 166, the process 162 proceeds by providing a tagging agent (e.g., an epitope or other appropriate biological directing moiety) adapted to target the radioisotope for a specific portion, e.g., an organ, of a patient. At block 168, the process 162 then proceeds by combining the radioactive isotope with the tagging agent to provide a radiopharmaceutical for nuclear medicine. In certain embodiments, the radioactive isotope may have natural tendencies to concentrate toward a particular organ or tissue and, thus, the radioactive isotope may be characterized as a radiopharmaceutical without adding any supplemental tagging agent. At block 170, the process 162 then may proceed by extracting one or more doses of the radiopharmaceutical into a syringe or another container, such as a container suitable for administering the radiopharmaceutical to a patient in a nuclear medicine facility or hospital. At block 172, the process 162 proceeds by injecting or generally administering a dose of the radiopharmaceutical into a patient. After a pre-selected time, the process 162 proceeds by detecting/imaging the radiopharmaceutical tagged to the patient's organ or tissue (block 174). For example, block 174 may include using a gamma camera or other radiographic imaging device to detect the radiopharmaceutical disposed on or in or bound to tissue of a brain, a heart, a liver, a tumor, a cancerous tissue, or various other organs or diseased tissue. FIG. 12 is a block diagram of an exemplary system 176 for providing a syringe having a radiopharmaceutical disposed therein for use in a nuclear medicine application. As illustrated, the system 176 includes the radioisotope elution systems 10, 110, 124. The system 176 also includes a radiopharmaceutical production system 178, which functions to combine a radioisotope 180 (e.g., technetium-99m solution acquired through use of the radioisotope elution system 10) with a tagging agent 182. In some embodiment, this radiopharmaceutical production system 178 may refer to or include what are known in the art as “kits” (e.g., Technescan® kit for preparation of a diagnostic radiopharmaceutical). Again, the tagging agent may include a variety of substances that are attracted to or targeted for a particular portion (e.g., organ, tissue, tumor, cancer, etc.) of the patient. As a result, the radiopharmaceutical production system 178 produces or may be utilized to produce a radiopharmaceutical including the radioisotope 180 and the tagging agent 182, as indicated by block 184. The illustrated system 176 may also include a radiopharmaceutical dispensing system 186, which facilitates extraction of the radiopharmaceutical into a vial or syringe 188. In certain embodiments, the various components and functions of the system 176 are disposed within a radiopharmacy, which prepares the syringe 188 of the radiopharmaceutical for use in a nuclear medicine application. For example, the syringe 188 may be prepared and delivered to a medical facility for use in diagnosis or treatment of a patient. FIG. 13 is a block diagram of an exemplary nuclear medicine imaging system 190 utilizing the syringe 188 of radiopharmaceutical provided using the system 176 of FIG. 12. As illustrated, the nuclear medicine imagining system 190 includes a radiation detector 192 having a scintillator 194 and a photo detector 196. In response to radiation 198 emitted from a tagged organ within a patient 200, the scintillator 194 emits light that is sensed and converted to electronic signals by the photo detector 196. Although not illustrated, the imaging system 190 also can include a collimator to collimate the radiation 198 directed toward the radiation detector 192. The illustrated imaging system 190 also includes detector acquisition circuitry 202 and image processing circuitry 204. The detector acquisition circuitry 202 generally controls the acquisition of electronic signals from the radiation detector 192. The image processing circuitry 204 may be employed to process the electronic signals, execute examination protocols, and so forth. The illustrated imaging system 190 also includes a user interface 206 to facilitate user interaction with the image processing circuitry 204 and other components of the imaging system 190. As a result, the imaging system 190 produces an image 208 of the tagged organ within the patient 200. Again, the foregoing procedures and resulting image 208 directly benefit from the radiopharmaceutical produced by the elution systems 10, 110, 124. While the invention may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. However, it should be understood that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cap all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the following appended claims.
	summary
	description	The present application claims the benefit of U.S. Provisional Patent Application No. 61/476,706, entitled “Electron-Optical System for High-Speed and High-Sensitivity Inspections,” filed Apr. 18, 2011, the disclosure of which is hereby incorporated by reference. 1. Technical Field The present invention relates generally to semiconductor manufacturing and related technologies. More particularly, the present invention relates to an electron beam column and methods for using the column in automated inspection and other applications. 2. Description of the Background Art Automated electron beam inspection systems typically use an electron beam column to scan an electron beam across a region of a substrate surface to obtain image data. The present disclosure provides a novel and inventive electron beam column for use in automated electron beam inspection and other applications. The present disclosure provides an electron beam inspection (EBI) system with substantially improved resolution and/or throughput for inspecting manufactured substrates. The EBI system may include an electron beam column comprising an electron gun, a scanner, an objective lens, and a detector. In accordance with one embodiment, the electron gun may include a gun lens having a flip-up pole piece configuration. In contrast, conventional electron guns have a flip-down pole piece configuration. In accordance with another embodiment, the scanner may comprise a dual scanner having a pre-scanner and a main scanner, and the detector may be configured between the electron gun and the pre-scanner. In one particular embodiment, the electrodes of the dual scanner are tapered. In accordance with another embodiment, the electron beam column may include a continuously-variable aperture configured to select a beam current. The continuously-variable aperture may be implemented as a square aperture formed by the edges of overlapping blades. Other embodiments relate to methods of using an electron beam column for automated inspection of manufactured substrates. In one embodiment, for example, an aperture size may be adjusted to achieve a minimum spot size given a selected beam current and a column-condition domain being used. A column-condition domain may be defined, for example, by a landing energy and an electric field strength at the surface of the target substrate Other embodiments, aspects, and features are also disclosed herein. FIG. 1 is a schematic diagram of an electron-optical column 100 for an electron beam inspection apparatus in accordance with an embodiment of the invention. The electron-optical column 100 includes innovative design features over previous electron-optical columns 100. The innovative design features result in the substantial improvement of the imaging resolution and/or throughput for the electron beam inspection apparatus. An innovative design for an electron-optical column is also described in commonly-owned U.S. patent application Ser. No. 12/958,174, filed Dec. 1, 2010, entitled “Electron Beam Column and Methods of Using Same.” The electron-optical column 100 includes a cathode source or emitter tip 102 which emits electrons and a gun lens (GL). The gun lens may include an upper pole piece 106 and a lower pole piece 108 in a magnetic field section and an anode and beam limiting aperture (BLA) 104 in an electric field section. The emitted electrons are accelerated through an opening in the anode and focused into a primary electron beam 110 which is directed along the optical axis of the column (defined as the z-axis) to an opening in a gate valve 112. The gate valve 112 divides the upper (gun) vacuum chamber from the lower (main) vacuum chamber. After being extracted from the cathode source or emitter tip 102, the electrons are at a lower energy level defined as the “extraction energy” (EE). After acceleration by the gun lens, the electrons in the primary electron beam 110 are at a higher energy level defined as the “beam energy” (BE). In one example implementation, the EE level may be in a range of 4 to 7 keV, and the BE level may be in a range of 8 to 12 keV. The particular energy levels to be used depend on the particular implementation. In another example implementation, an ultra high BE of up to 35 keV may be used by providing a high voltage stand-off capability in a column which is very short in the z-dimension. The BE may be made variable to take advantage of high BE electron-optics for reducing electron-electron interactions without taking an extra high voltage risk. In accordance with an embodiment of the invention, the pole pieces of the magnetic field section of the gun lens in FIG. 1 are arranged in a flip-up pole piece configuration. In a flip-up pole piece configuration, the gap 105 between the upper and lower pole pieces (104 and 106) is positioned at the bottom of the pole pieces. In contrast, a conventional gun lens has pole pieces arranged in a flip-down pole piece configuration. In a flip-down pole piece configuration, the gap between the upper and lower pole pieces is positioned at the top of the pole pieces. FIG. 2 contrasts flip-up and flip-down pole piece configurations. In the lower vacuum chamber, the primary electron beam 110 may pass through beam-current selection aperture which may be used to select a final beam current to the target substrate for imaging. In accordance with one embodiment of the invention, the beam-current selection aperture may comprise a continuously-variable aperture (CVA) 114. Example embodiments of the CVA 114 are described below in relation to FIGS. 3A, 3B and 3C. While a square-shaped CVA is depicted in FIGS. 3A, 3B and 3C, the CVA may be more generally implemented as an N-side aperture with N equal sizes, where N=3, 4, 5, 6, and so on. Innovative CVA designs are also described in commonly-owned U.S. patent application Ser. No. 13/006,999, filed Jan. 14, 2011, entitled “High-Vacuum Variable Aperture Mechanism and Method of Using Same.” The CVA 114 may be configured or adjusted to an optimized aperture size, Dopt. In accordance with an embodiment of the invention, the optimized aperture size may be indexed to a particular column condition domain. Two example column condition domains and their corresponding optimized aperture sizes are described below in relation to FIG. 4. The primary electron beam 110 may be focused into a beam spot on the surface of the target substrate 118 by an objective lens (OL) 116. The objective lens 116 is preferably configured to have a very low spherical aberration coefficient and a very low chromatic aberration coefficient. The objective lens 116 may also retard the energy of (i.e. decelerate) the electrons in the primary beam from the “beam energy” (BE) level to a lower “landing energy” (LE) level. The particular energy levels to be used depend on the particular implementation. The objective lens 116 may include, in a magnetic section, an inner pole piece and an outer pole piece, where the inner pole piece is depicted in FIG. 1. In accordance with an embodiment of the invention, the pole pieces of the objective lens 116 may be configured such that the target substrate 118 is heavily immersed in the magnetic field produced by the objective lens 116. As shown, the objective lens 116 may also include, in an electrostatic section, an electrically-grounded (GND) plate 120 and a charge-control (CC) plate 122. The CC plate 122 may be used to establish the electric field (E-field) strength on the surface of the target substrate 118. The voltage applied to the CC plate 122 may be a positive or a negative voltage with respect to the ground plate 120. In accordance with an embodiment of the invention, the electrostatic section of the objective lens 116 may also include a pre-charge-control (Pre-CC) 121 plate. The Pre-CC plate 121 may be positioned between the ground plate 120 and the CC plate 122. The voltage applied to the Pre-CC plate 121 may be varied to provide an additional degree of freedom so as to further minimize lens aberrations and further optimize charge control at the target substrate 118. In addition, the voltage applied to the Pre-CC plate 121 may be used to optimize the retardation (lowering) of the energy of the primary electron beam as it approaches the target substrate. The primary electron beam 110 may be scanned over an area on the target substrate using a scanning system. The scanning system may comprise a dual-deflection scanner including a pre-scanner/stigmator 124 and a Wien filter/main scanner 126. The scanning system may be utilized to deflect the e-beam in the x and y directions (for example, in a raster pattern) so as to scan the beam over a region within the field of view of the imaging apparatus. In one embodiment, the pre-scanner 124 and the main scanner 126 are both configured with a tapered shape. The shape of the scanners is tapered the thickness of the electrodes varies from a thicker end to a thinner end. The thicker end is configured closer to the manufactured substrate while the thinner end is configured closer to the electron source. The impingement of the primary electron beam 110 into the surface of the target substrate 118 causes emission of secondary electrons 128. The secondary electrons are extracted from the target substrate 118 and deflected away from the z-axis by the Wien filter/main scanner 126. For example, the electrostatic deflection field for the Wien filter may be that generated by and used for the main scanning deflector, and the magnetic deflection field for the Wien filter may be generated by a two-pair saddle yoke with coils. The electrostatic and magnetic fields in the Wien filter are perpendicular and balanced such that the primary electron beam is not deflected while the secondary electrons are deflected. A detector 130 may then detect the secondary electrons. The detector 130 may be positioned, for example, in between the pre-scanner 124 and the CVA 114. The secondary electron detection signal may be synchronized or coordinated with the primary electron scanning signal such that an image of the scanned area may be produced. FIG. 3A shows a cross-sectional view of a square aperture with overlapping blades 306 in accordance with an embodiment of the invention. Applicants have determined that such a square aperture may be configured to form a continuously-variable aperture, and that such a continuously-variable aperture may contribute a further 10% to 100% improvement of resolution across column conditions ranging from landing energies of 50 to 5,000 eV and wafer electric fields ranging from −100 V/mm to +2,000 V/mm. As seen, the aperture base 302 may comprise a circular hole 304 in a thinner section at its middle. The circular hole 304 may be oversized in that it is larger than the largest needed square aperture to be formed by the overlapping blades. In one implementation, the aperture base 302 may comprise a molybdenum round aperture. The overlapping blades 306 may be supported by the top surface of the aperture base 302. The overlapping blades 306 may include at least one upper aperture blade 306-U and at least one lower aperture blade 306-L. In one implementation, the blades 306 may comprise thin molybdenum blades. In some implementations, a spacer 307 may be configured between the base 302 and the upper aperture blade 306-U to raise the height of the upper aperture blade 306-U above that of the lower aperture blade 306-L. The thickness of the spacer 307 may be slightly thicker than the thickness of the lower aperture blade 306-L such that portions of the upper aperture blade 306-U may slide over the lower aperture blade 306-L without contact between the blades being made. In accordance with an embodiment of the invention, a resultant square aperture 312 may be formed from a plan view perspective. The perimeter of the square aperture 312 may be formed from edges of the aperture blades 306 and may be centered on the electron-optical axis of the column. FIG. 3B shows a plan view of a square aperture which is formed by overlapping two V-cut blades in accordance with an embodiment of the invention. The right side of the figure shows the individual aperture parts, and the left side of the figure shows the parts as they are put together to form the square aperture. As shown, the two blades 306 may be attached to the base 302 and/or spacer 307 by spot welding. In this embodiment, the upper and lower blades (306-U and 306-L) each have a V-cut opening. When the blades are configured to form the square aperture, the edges of their V-cut openings form the perimeter of the square aperture. The upper and lower blades (306-U and 306-L) may be slid horizontally to increase or decrease their overlap. Increasing the overlap of the blades results in a smaller square aperture, while decreasing their overlap results in a larger square aperture. FIG. 3C shows a plan view of a square aperture which is formed by overlapping four rectangular blades in accordance with an embodiment of the invention. The right side of the figure shows the individual aperture parts, and the left side of the figure shows the parts as they are put together to form the square aperture. As shown, the four blades 306 may be attached to the base 302 by spot welding. In this embodiment, two of the blades are configured as lower blades 306-L and may be attached directly to the base 302, while the other two blades are configured as upper blades 306-U and may be attached on top of portions of the lower blades 306-L. For example, as indicated in plan view of FIG. 3C, the lower blades 306-L may be arranged above and below the center of the circular opening 304, while the upper blades 306-U may be arranged on the left and right of the center of the circular opening 304. As such, the edges of the four blades 306 form the perimeter of the square aperture. Increasing the overlap of the blades 306 results in a smaller square aperture, while decreasing their overlap results in a larger square aperture. In accordance with one embodiment, the horizontal positioning of the blades 306 (configured as shown in either FIG. 3B or FIG. 3C, for example) may be driven electrically and measured by capacitative sensors mounted symmetrically around the center of the aperture. The aperture size may be changed from one size to another within a couple of seconds. Advantageously, such a square aperture is continuously variable in that its size may be continuously (rather than discretely) varied over a size range. FIG. 4 is a graph showing spot size versus aperture size for two different column conditions (two different domains) in accordance with an embodiment of the invention. The performance of an electron-beam inspection instrument may be characterized by spot size (SS) and beam current (BC), where the former represents the resolution of the instrument and the latter represents the throughput of the machine. The BC finally reaching the sample may be selected by a beam current selection aperture with aperture size D positioned in between the gun and objective lenses. Inspections for different wafer layers normally require different column conditions, i.e. different electron landing energies (LE) on the wafer surface and different electric field strengths (E) applied on the wafer surface. Different column conditions, particularly in terms of different LE and E, are referred to herein as different domains. From an electron-optics point of view, the minimal SS for different column-condition (LE, E) domains requires different optimal apertures Dopt, even at the same BC. The optimal aperture size Dopt fundamentally reflects a balance of optical blurs between lens aberrations and electron-electron interactions, where the electron-electron interactions are dominant when D<Dopt while the lens aberrations are dominant when D>Dopt. Given a particular BC, the optimal aperture size Dopt may be determined to be the aperture size D where the SS is at a minimum. As shown in FIG. 4, the minimal SS may be found at the optimum aperture size Dopt1 for the curve for (LE, E) domain 1 and at the optimum aperture size Dopt2 for the curve for (LE, E) domain 2. In this example, the minimum SS for domain 2 is smaller than the minimum SS for domain 1. A prior method utilizes one aperture size D (corresponding to a single BC) to cover the entire column-condition space in terms of (LE, E). However, given the discussion above, this prior method fails to minimize the spot size (SS) at every column condition across the entire (LE, E) space (because the optimal aperture sizes Dopt are different at different (LE, E) domains even at the same BC). In accordance with one aspect of the present invention, the optimized aperture Dopt is indexed to the (LE,E) domain in the spot size minimization. In a preferred embodiment for wide applications, the LE and E are extended to a large column-condition range, e.g.: LE=50 eV to 5,000 eV and E=−100 V/mm to +2,000 V/mm respectively. The optimized apertures across the (LE, E) domain may be implemented with a variable aperture device or an aperture rod on which multi-apertures are installed for best fitting to different wafer layers of applications. Applicants believe that the presently-disclosed aperture domain concept (in which the optimized aperture size is indexed not only to the BC, but also to LE and E) and its use provide for improved resolution in terms of SS in a range of about 10% to 100% across the electron-beam inspection application condition space. In one implementation, optimal aperture sizes may be determined given a selected beam current and a particular column-condition domain (which may be specified, for example, by the beam current, landing energy, and electric field strength on the surface of the target substrate). The data providing the optimal aperture size given a selected beam current and a particular column-condition may be stored in memory or other data storage which is accessible to the control system for the electron beam column. Subsequently, when a beam current is selected, the controller may cause the aperture size to be adjusted to the optimal aperture size which is associated with a particular column-condition domain being used. Furthermore, it is also contemplated that the column-condition domain may be adjusted (and the aperture size adjusted to the optimal aperture size for the resultant domain) so as to further decrease the beam spot size. FIG. 5 is a graph showing an example of electron-optical performance improvement in accordance with an embodiment of the invention. Shown in FIG. 5 are plots of spot size (SS) versus beam current (BC), both in log scale, for a conventional column and for a column configured as disclosed herein per FIG. 1. As seen, at a same spot size, the column as disclosed herein per FIG. 1 has a higher beam current by more than four times over the conventional column. FIGS. 6A-6D show computer simulations (computer modeling) of electron beam spots generated using a conventional circular aperture and using a square aperture in accordance with an embodiment of the invention. Lens aberrations and electron-electron interactions are included in the modeling. FIG. 6A shows two-dimensional contour modeling of a square aperture in accordance with an embodiment of the invention, while FIG. 6B shows two-dimensional contour modeling of a round aperture. FIG. 6C shows three-dimensional profile modeling of a square aperture in accordance with an embodiment of the invention, while FIG. 6D shows three-dimensional profile modeling of a round aperture. As seen from FIGS. 6A-6D, the electron beam spot generated using a square aperture is comparable to those generated using a circular aperture. FIGS. 7A and 7B show electron images formed using a conventional circular aperture and using an overlapping square aperture in accordance with an embodiment of the invention. FIG. 7A shows an electron beam image obtained with a square aperture formed using overlapping blades in accordance with an embodiment of the invention. FIG. 7B shows an electron beam image obtained with a round aperture. As seen, there is no visible degradation in the image formed by the overlapping square aperture. In fact, the image formed by the overlapping square aperture appears to have less blurring and better resolution. Applicants have determined that there is no visible image degradation in the image formed by the overlapping square aperture even when using high beam currents. Advantageously, by using the apparatus and methods disclosed herein, the electron-optics imaging resolution may be substantially improved, and/or the throughput for an electron inspection apparatus may be substantially increased. The above-described diagrams are not necessarily to scale and are intended be illustrative and not limiting to a particular implementation. In the above description, numerous specific details are given to provide a thorough understanding of embodiments of the invention. However, the above description of illustrated embodiments of the invention is not intended to be exhaustive or to limit the invention to the precise forms disclosed. One skilled in the relevant art will recognize that the invention can be practiced without one or more of the specific details, or with other methods, components, etc. In other instances, well-known structures or operations are not shown or described in detail to avoid obscuring aspects of the invention. While specific embodiments of, and examples for, the invention are described herein for illustrative purposes, various equivalent modifications are possible within the scope of the invention, as those skilled in the relevant art will recognize. These modifications can be made to the invention in light of the above detailed description. The terms used in the following claims should not be construed to limit the invention to the specific embodiments disclosed in the specification and the claims. Rather, the scope of the invention is to be determined by the following claims, which are to be construed in accordance with established doctrines of claim interpretation.
	description	This application is the National Phase of International Application PCT/GB2014/051525 filed May 16, 2014, which designated the U.S. That International Application was published in English under PCT Article 21(2) on Nov. 20, 2014 as International Publication Number WO 2014/184589A1. PCT/GB2014/051525 claims priority to U.K. Application No. 1308818.2 filed May 16, 2013. Thus, the subject nonprovisional application also claims priority to U.K. Application No. 1308818.2 filed May 16, 2013. The disclosures of both applications are incorporated herein by reference. The present invention relates to x-ray detection apparatus and in particular x-ray detection apparatus utilising filters. X-ray detectors have a wide variety of uses and are available in many configurations. The present invention relates to x-ray detectors including structures configured to perturb an x-ray energy spectrum emanating from an x-ray source, prior to the x-ray energy spectrum impinging on an x-ray detector. According to a first aspect of the invention there is provided an x-ray detection apparatus as specified in Claim 1. Preferred aspects of the apparatus of this aspect of the invention are specified in the claims dependent on Claim 1, the description and the drawings. According to a second aspect of the invention there is provided a method of analysing at least one material property of a substance as specified in Claim 11. Preferred aspects of the method of this aspect of the invention are specified in the claims dependent on Claim 15, the description and the drawings. According to the invention there is provided an x-ray/gamma-ray detection apparatus, the apparatus including at least one x-ray/gamma-ray detector comprising, and a plurality of structures each configured to perturb an x-ray/gamma-ray energy spectrum differently, wherein said structure lies next to the at least one x-ray/gamma-ray detector. The apparatus may include a position for a material under test. The apparatus may include an x-ray/gamma-ray source. Preferably, the x-ray/gamma-ray source, at least one of the at least one x-ray/gamma-ray detector, the position for a material under test, and one of the plurality of structures are aligned wherein the x-ray/gamma-ray source is arranged to direct an x-ray/gamma-ray energy spectrum to impinge upon the at least one x-ray/gamma-ray detector, the structure configured to perturb the x-ray/gamma-ray energy spectrum, and positioned material under test, wherein said structure lies between the position for material under test and the x-ray/gamma-ray detector. The combination of the detector and the plurality of structures without the x-ray/gamma-ray source and position for a material under test is useful where the material under test is itself radio active. Preferably, the or each x-ray/gamma-ray detector is a single pixel detector. Preferably, the x-ray/gamma-ray detection apparatus, the or each x-ray/gamma-ray detector includes a scintillator. Preferably, each of the plurality of structures is mounted on a member adapted to provide for placing of a selected one of the plurality of structures such that it lies in alignment with the at least one x-ray/gamma-ray detector. Preferably, the member is a wheel and the structures are mounted on the wheel. Preferably, the apparatus further comprises means to move the member so as to place a selected one of the plurality of structures in alignment with the at least one x-ray/gamma-ray detector. Preferably, the means to move the member includes a motor. The x-ray/gamma-ray detection apparatus may comprise two x-ray/gamma-ray detectors aligned with each other and the x-ray/gamma-ray source, wherein the structure is situated between the two detectors. The x-ray/gamma-ray detection apparatus may comprise a plurality of x-ray/gamma-ray detectors arranged in a linear array. Preferably, each x-ray/gamma-ray detector is associated with a structure and each structure is different to its adjacent structure. The x-ray/gamma-ray detection apparatus may comprising two linear arrays of x-ray/gamma-ray detectors aligned with each other and the x-ray/gamma-ray source. Preferably, each x-ray/gamma-ray detector of one or both of the two linear arrays is associated with a structure and each structure is different. The x-ray/gamma-ray detection apparatus may comprise at least two linear arrays of x-ray/gamma-ray detectors, and wherein the linear arrays lie in different planes. The x-ray/gamma-ray detection apparatus may comprise a plurality of linear arrays of x-ray/gamma-ray detectors and a plurality of structures, each linear array associated with one of the plurality of structures and wherein adjacent structures are different. According to an aspect of the invention there is provided a method of analysing at least one material property of a substance using x-ray/gamma-ray detection apparatus of the invention, comprising the steps of: a) Positioning a material in the apparatus; b) Causing the x-ray/gamma-ray source to direct an x-ray/gamma-ray energy spectrum to impinge upon the at least one x-ray/gamma-ray detector, one of the plurality of structures configured to perturb the x-ray/gamma-ray energy spectrum, and positioned material under test; c) Causing the x-ray/gamma-ray source to direct an x-ray/gamma-ray energy spectrum to impinge upon the at least one x-ray/gamma-ray detector, another of the plurality of structures configured to perturb the x-ray/gamma-ray energy spectrum, and positioned material under test; d) Repeating step b for other structures of the plurality thereof one or more times; e) Analysing the signal of detector at each step or repeated step. The method may comprise the further step of recording the signals for detector with each different structure of the plurality of structures present and comparing the recorded signals with the recorded signals for the detector when successive structures are aligned with the x-ray/gamma-ray source and the detector. The method may comprise the further step of performing the step of Claim 16 without the object present. The method may comrpise the further step of comparing the current differences between recorded signals between detectors when successive structures are aligned with the x-ray/gamma-ray source and the detector as determined by previous method steps. The method may comprise the further step of following previous method steps for at least one known material and storing the differences in a database, and comparing the differences between recorded signals for an object under test with the differences between recorded signals in the database. The method may comprise the further step of producing at least one output representative of the at least one material property. The method may comprise the further step of displaying the at least one output on a display means. FIG. 1a illustrates a single shot x-ray detector apparatus comprising an x-ray source 1, an object 2, a single pixel x-ray detector 3 and a filter 4. The x-ray detector may be of the indirect type utilising a scintillator to convert incident x-ray photons into visible spectrum photons, those visible spectrum photons being converted to an electrical signal. Alternatively, the detector may be a silicon drift detector or a hybrid detector. In FIG. 1a a single filter 4 is shown. The filter 4 perturbs the x-ray shadow of the object 2 in a defined and known manner. Using one filter in this way it would be possible to detect the presence of an isotope. However, in order to detect not only the presence of a radio-active isotope, but also the identity of the isotope it is necessary to obtain one shot with one filter and another shot with a different filter. However, in order to achieve this, the radio isotope must be present for a sufficiently long time for the filter 4 to be changed. In FIG. 1b, the filter 4 is one of a plurality of filters 4a to 4b all mounted on a wheel 5. By rotating the wheel 5, multiple shots of the object may be taken, each shot having the x-ray shadow of the object 2 perturbed in a different and known manner. Information from such a set of shots may be used to derive material type and thickness information. Referring now to FIG. 2, the multi-shot detector apparatus comprises an x-ray source 1, an object 2, a first detector 3a, a second detector 3b and a filter 4 situated between the two detectors 3a, 3b. X-rays emitted from the x-ray source 1 pass through the object 2, which attenuates the x-ray signal, through the first detector 3a and filter 4, each of which further attenuates the x-ray signal, finally impinging on the detector 3b. Detectors 3a and 3b are both single pixel detectors. A significant amount of information about the object can be gained by detecting the x-rays attenuated only by the object 2, and those x-rays attenuated by the first detector 3a and the filter 4. FIGS. 3a to 3e illustrate linear array x-ray detectors, also known as 2-D cameras. This type of linear array detector is typically used in industrial applications, often to inspect items carried on conveyors, for example in airport security. As the item passes by the linear array, images of the part of the item aligned with the linear array are taken. These images are stacked together to form an image of the item. The embodiments of the invention illustrated in FIGS. 3a to 3e include a multi-absorption plate. The multi-absorption plate includes a plurality of regions configured to create different pertubations in the x-ray energy spectrum emanating from an x-ray source. FIG. 3a illustrates a linear array x-ray detector apparatus comprising an x-ray source 1, a linear array detector 30 comprising x-ray detector elements 30a to 30g, and a multi-absorption plate 40 a repeating array of absorption elements 40a to 40d, each of the absorption elements 40a to 40d absorbing an incident x-ray energy spectrum differently. An object 2 travels along the axis x-x. For example the object 2 may be mounted on a conveyor, with the x-ray source 1 being mounted above the conveyor and the linear array detector 30 and multi-absorption plate 40 being mounted below. The lower x-ray detector 30 shown in FIG. 3a is an alternative to the x-ray detector described above. In this x-ray detector 30 the multi-absorption plate is attached to the x-ray detector 30. The x-ray detector elements 30a to 30g may be of the indirect type utilising a scintillator to convert incident x-ray photons into visible spectrum photons, those visible spectrum photons being converted to an electrical signal. Alternatively, other types of x-ray detector may be used, such as a silicon drift detector, a hybrid detector or a direct detector. The presence of the multi-absorption plate 40 imposes a plurality of energy shifts on the x-ray energy spectrum. With this additional information it is possible to make deductions as to the type and thickness of materials contained in the item 2. It is therefore possible to obtain very similar information with a reduced number of detectors and because the same linear array of detectors is being used, intrinsic variabily in the image is reduced. Whilst temporal errors are greater than would be the case with an arrangement using multiple linear array detectors, these errors can be minimised by for example synchronising the movement of the item, i.e. the conveyor on which it is situated, with the capture frame rate of the array. Material type and/or thickness information may be embodied within an image captured by the x-ray detector elements 30a to 30g, for example by colour coding. The FIG. 3b configuration comprises a plurality of linear array detectors 30, four linear array detectors being shown. Each linear array detector is comprised of x-ray detector elements 30a to 30g. In this embodiment rather than the x-ray detector elements 30a to 30g being aligned with a multi-absorption plate, the elements 30a to 30g of each detector 30 are aligned with an absorption plate 41-44, each absorption plate being uniform. However, whilst each of the absorption plates 41-44 is uniform, each is also different. Hence, each linear detector array 30 has its own unique absorption plate. As the item 2 moves past the linear arrays 30 along the axis x-x, an image is built up as each array 30 sees the same part of the item sequentially. The images captured by each linear array 30 are subject to a different x-ray energy shift due to the differences between the absorption plates 41-44. These different x-ray energy shifts allow the material and thickness of the item to be determined. FIG. 3c illustrates a configuration similar to that shown in FIG. 3a, with an additional linear detector array 30′ aligned beneath the linear detector array 30. Each of the linear detector arrays is provided with a multi-absorption plate 40 in the same way as described with reference to FIG. 3a. The apparatus follows the same principles as described with reference to the FIG. 2 embodiment, that is the signal detected by the second linear array detector 30′ has been attenuated not only by the item 2 and the multi-absorption plate 40′, but also the first linear detector array 30, and its associated multi-absorption plate 40. One of the multi-absorption plates 40, 40′ may be omitted. FIGS. 3d and 3e illustrate embodiments of linear array x-ray detector apparatus configured to provide three dimensional information about an object in addition to the materials and thickness identification provided for by the embodiments illustrated in FIGS. 3a to 3c. The embodiment of FIG. 3d is essentially a variant of the embodiment illustrated in FIG. 3a, with second and third linear detector arrays 30 mounted to each side of a central linear detector array 30 and at an angle thereto. In FIG. 3e a group of four linear detector arrays 30 is mounted beneath an item 2 moving along an axis x-x. Each of the linear detector arrays 30 is provided with a multi-absorption plate 40 as described with reference to FIG. 3a. An x-ray source 1 is mounted above the item 2 and the linear detector arrays 30. The detector arrays 30 lie parallel to one another and across the direction of travel x-x of the item 2, substantially normal thereto. However, as can be seen from FIG. 3, each linear detector array 30 lies at an angle to the neighbouring linear detector array 30. The detector elements 30a to 30g, 30a′ to 30g′ may be single pixel x-ray detectors, or alternatively they may be cameras which may be low resolution x-ray cameras. Where the detector elements 30a to 30g, 30a′ to 30g′ are cameras the multi-absorption plate associated with the linear array may include different regions aligned with an individual detector. To determine a material property of an object 2 the x-ray source 1 is caused to direct an x-ray energy spectrum through the object 2, the structure 4, 40, to impinge upon the detector 3a, 3b, 30a-30f. Visible wavelength photons emitted by the scintillator are then analysed according to the following steps: Step (i)—The detectors 3a, 3b, 30a-30f are single pixel detectors: the intensity of visible wavelength photons recorded by the detector for each detector is compared with the recorded intensity for its adjacent or successive detectors and the differences in intensity are recorded; Step (ii)—The intensity of visible wavelength photons recorded by each detector is compared with the recorded intensity for its adjacent or successive detectors and the differences in intensity are recorded without the object 3 present; Step (iv)—The current differences between recorded intensities between adjacent detectors as determined by the method steps (i) and (ii) are compared; Step (v)—Following the method steps (i) to (iv) for at least one known material and storing the differences in a database; and Step (vi)—Comparing the differences between recorded intensities for a substance under test with the differences between recorded intensities for known substances from the database. Where the x-ray detector does not use a scintillator intensities and energies are recorded. FIG. 4 is a block diagram of a system according to an embodiment of the invention in which the detector 3, 30 (which may be the detector of any of the previously described embodiments or other embodiments falling within the scope of the claims) provides an output to a data recording means 50. The data recording means is in communication with a data processor as is a database 51 in which data characteristic of known materials are recorded. The data recording means 50 and the database 51 are in communication with a data processor 52 which runs data processing software, the data processing software comparing information from the detector, preferably via the data recording means, and the database to determine a material property of an object 2. A data output interface 53, is preferably included to which a determination of the data processing software may be outputted. Such an interface 53 may be connected to a VDU or may cause an object to be accepted or rejected, for example where the apparatus is used in quality control. It is not necessary that all values are stored in the database. Where matching values are not recorded in the database, a value for a material under test may be interpolated. References herein to x-rays are references to x-rays and/or gamma-rays. The structures configured to perturb the x-ray/gamma-ray energy spectrum are at least partially transparent to x-ray/gamma-ray radiation. Their function is to perturb rather than block the x-ray/gamma-ray energy.
	description	This application claims priorities from Korean Patent Application No. 10-2014-0020816, filed on Feb. 21, 2014, in the Korean Intellectual Property Office and Korean Patent Application No. 10-2014-0108457, filed on Aug. 20, 2014, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. 1. Field Apparatuses and methods consistent with exemplary embodiments relate to an X-ray grid structure for an X-ray detector, and an X-ray apparatus including the X-ray grid structure. 2. Description of the Related Art X-ray apparatuses are used as medical imaging apparatuses for obtaining medical images of an object by passing X-rays through the person's body. Such X-ray apparatuses are operated based on X-rays passing through a human body that are absorbed at different rates in different types of tissue. X-ray apparatuses are relatively simple and fast in taking medical images of objects (e.g., patients) as compared with other medical imaging apparatuses such as magnetic resonance imaging (MRI) apparatuses and computerized tomography (CT) apparatuses. When X-rays pass through a human body, some of the X-rays may be absorbed in the human body, and some of the X-rays may scatter in directions different from the direction in which the X-rays are incident on the human body. Such scattering of rays may lower the quality of X-ray images. To prevent such deterioration of image quality, X-ray grids which selectively transmit X-rays may be used. If an X-ray grid is disposed between a human body and an X-ray detector, the influence of scattering rays may be minimized. The use of an X-ray grid may be determined according to the part of a human body to be X-rayed. For example, when a person's chest is X-rayed, an X-ray grid may be used because a large number of X-rays is scattered. However, when a relatively thin part of a person such as a hand or foot is X-rayed, an X-ray grid does not need to be used because a smaller number of X-rays is scattered. Therefore, before taking an X-ray image, an operator may attach or detach an X-ray grid to or from an X-ray detector according to characteristics of an object to be X-rayed. Exemplary embodiments address at least the above problems and/or disadvantages and other disadvantages not described above. Also, the exemplary embodiments are not required to overcome the disadvantages described above, and may not overcome any of the problems described above. One or more exemplary embodiments include an X-ray grid structure which is light and easily attachable to an X-ray detection unit, and an X-ray apparatus including the X-ray grid structure. One or more exemplary embodiments include an X-ray grid structure including a plurality of holders which are simple and easy to manufacture, and an X-ray apparatus including the X-ray grid structure. According to an aspect of an exemplary embodiment, there is provided an X-ray grid structure configured to be detachably attached to an X-ray detector, the X-ray grid structure including an X-ray grid configured to selectively transmit X-rays, and holders fixed along an outer edge of the X-ray grid, wherein at least one of holders includes an elastic material and is configured to bendable in a direction crossing an attachment direction, which is a direction of attaching the X-ray detector to the X-ray grid. Holders may be spaced apart from each other along the outer edge of the X-ray grid. The elastic material may include at least one of polyurethane and silicone. The at least one of holders may have a hardness of about 70 to about 95 as measured by a Shore A durometer. The at least one of the holders may include a fixing portion fixed to the X-ray grid, and a support portion configured to be detachably attached to the X-ray detector and configured to support the X-ray detector. The X-ray detector may include a front side facing the X-ray grid, a rear side opposite the front side, and a lateral side between the front and rear sides, and wherein the support portion may include a side support portion configured to support the lateral side of the X-ray detector, and a rear support portion configured to support the rear side of the X-ray detector. The rear support portion may have a length of about 3 mm to about 6 mm. The fixing portion may be fixed to the X-ray grid using an adhesive. The fixing portion may include a slope, so that a height of the fixing portion increases in an outward direction from a center portion of the X-ray grid. The rear support portion may include a slope, so that a height of the rear support portion increases in an outward direction from a center of the X-ray grid. All of the holders may have a same shape and are formed of the same elastic material. The X-ray grid may have a rectangular shape, and the holders may be disposed at corners of the X-ray grid. When the X-ray grid structure is attached to the X-ray detector, edges of the X-ray grid may be disposed inward from the outer edge of the X-ray detector with respect to a center portion of the X-ray grid. The X-ray grid may include a rear side facing the X-ray detector and a front side opposite to the rear side, and reinforcement films disposed on the front side and the rear side of the X-ray grid to reinforce the X-ray grid. The reinforcement films may include carbon fiber. The X-ray grid may include a front side facing the X-ray detector and a rear side opposite to the front side, and at least one of the holders may include: a first member contacting the rear side of the X-ray grid; a second member contacting the front side of the X-ray grid; and a coupling member fastening the first member and the second member together. The first member may include at least one coupling hole structure protruding toward the second member for coupling with the coupling member. The second member may include a connection hole receiving the coupling member and connected to the coupling hole structure. The coupling member may include a body portion coupled to the coupling hole structure and a head portion for pressing the second member. The body portion may include a threaded region screwed into the coupling hole structure and a non-threaded region on which a thread is not formed. The second member may include an elastic material. The first member may include a material different from a material included in the second member. The first member may have bending strength greater than that of the second member. According to an aspect of another exemplary embodiment, there is provided an X-ray apparatus including an X-ray radiation unit configured to emit X-rays, an X-ray detector configured to detect the X-rays having passed through an object, and an X-ray grid structure which is configured to be detachably attached to the X-ray detector, and includes an X-ray grid configured to selectively transmit X-rays, and holders fixed along an outer edge of the X-ray grid, wherein at least one of holders includes an elastic material and is configured to bend in a direction crossing an attachment direction which is a direction of attaching the X-ray detector to the X-ray grid. The X-ray apparatus may further include wheels configured to move the X-ray apparatus. Exemplary embodiments are described in greater detail below with reference to the accompanying drawings. In the following description, like drawing reference numerals are used for like elements, even in different drawings. The matters defined in the description, such as detailed construction and elements, are provided to assist in a comprehensive understanding of the exemplary embodiments. However, it is apparent that the exemplary embodiments can be practiced without those specifically defined matters. Also, well-known functions or constructions are not described in detail since they would obscure the description with unnecessary detail. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. Expressions such as “at least one of,” when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list. Hereinafter, structures and operations of an X-ray grid structure and an X-ray apparatus including the X-ray grid structure will be described in detail with reference to the accompanying drawings according to exemplary embodiments. In the following descriptions of the exemplary embodiments, although the terms first, second, third, and fourth are used to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from other elements. In the present disclosure, the term “image” may refer to multi-dimensional image data including discrete image elements (for example, pixels of two-dimensional images, and voxels of three-dimensional images). Furthermore, in the present disclosure, the term “object” may refer to a person, an animal, a person's part, an animal's part, or the like. For example, the term “object” may refer to blood vessels or an organ such as the liver, the heart, the uterus, the brain, the breasts, and the abdomen. Furthermore, the term “object” may refer to a phantom. The phantom is an object having a density, volume, and effective atomic number similar to those of a living organism. For example, the phantom may be a sphere object having features similar to those of a human body. Furthermore, in the present disclosure, the term “operator” may refer to a medical service person such as doctors, nurses, medical laboratory technologists, medical imaging technicians, and medical equipment repairmen. However, the term “operator” is not limited thereto. FIG. 1 is a view illustrating an X-ray apparatus 100 according to an exemplary embodiment. The X-ray apparatus 100 of FIG. 1 may be a fixed or movable X-ray apparatus. Referring to FIG. 1, the X-ray apparatus 100 may include a workstation 110, an X-ray radiation unit 120, a high voltage generator 121, and an X-ray detector 130. The workstation 110 includes an input unit 111 and a controller 112. An operator may input commands such as an X-ray radiation command for operating the X-ray apparatus 100, and the controller 112 may controls overall operations of the X-ray apparatus 100. The high voltage generator 121 generates a high voltage and applies the high voltage to an X-ray source 122 to generate X-rays. The X-ray radiation unit 120 includes the X-ray source 122 configured to receive the high voltage from the high voltage generator 121 and emit X-rays; and a collimator 123 configured to guide X-rays emitted from the X-ray source 122. The X-ray detector 130 detects X-rays emitted from the X-ray radiation unit 120 and passing through an object. The X-ray apparatus 100 may further include an operating device 140, and the operating device 140 may include a sound generator 141 configured to generate sounds under the control of the controller 112 so as to provide information about imaging procedures such as X-ray radiation. The workstation 110, the X-ray radiation unit 120, the high voltage generator 121, and the X-ray detector 130 may be connected to one another through wires or wirelessly. In the latter case, clock synchronization devices may be used. Examples of the input unit 111 may include a keyboard, a mouse, a touchpad, a speech recognizing device, a fingerprint reader, an iris recognizing device, and any other input devices known to those of ordinary skill in the related art. An operator may input an X-ray radiation command through the input unit 111, and the input unit 111 may include a switch to receive such commands. If the input unit 111 generates a radiation signal, the controller 112 may signal the sound generator 141 to generate a sound to inform an object of X-ray radiation. In addition, the sound generator 141 may generate other sounds to provide information about other imaging procedures. In FIG. 1, the sound generator 141 is included in the operating device 140. However, the exemplary embodiments are not limited thereto. For example, the sound generator 141 may be disposed in a unit other than the operating device 140. For example, the sound generator 141 may be included in the workstation 110 or may be disposed on a wall of an X-ray room in which an object is x-rayed. The controller 112 controls the positions of the X-ray radiation unit 120 and the X-ray detector 130, imaging timing, and other imaging conditions according to imaging conditions set by an operator. In detail, the controller 112 may control the high voltage generator 121 and the X-ray detector 130 according to a command input through the input unit 111, so as to adjust the timing, intensity, and range of X-ray radiation. In addition, the controller 112 generates X-ray images of an object by using image data received from the X-ray detector 130. In detail, if the controller 112 receives image data of an object from the X-ray detector 130, the controller 112 may remove noise from the image data and may control the dynamic range and interleaving of the image data to generate an X-ray image of the object. The X-ray apparatus 100 of FIG. 1 may further include an output unit to output an X-ray image generated by the controller 112. In addition, the output unit may output a user interface (UI) and information such as user or object information that may be used to manipulate the X-ray apparatus 100. Examples of the output unit may include a printer, a CRT display, an liquid crystal display (LCD), a plasma display panel (PDP) display, an organic light emitting diode (OLED) display, a field emission display (FED), a light emitting diode (LED) display, a vacuum fluorescent display (VFD), a digital light processing (DLP) display, a primary flight display (PFD), a 3D display, a transparent display, and any other output device known to those of ordinary skill in the related art. The workstation 110 shown in FIG. 1 may further include a communicator capable of communicating with devices such as a server 162, a medical device 164, and a portable terminal 166 through a network 150. The communicator may be connected to the network 150 through a wired or wireless connection for communicating with the server 162, the medical device 164, or the portable terminal 166. The communicator may transmit diagnosis data of an object through the network 150. In addition, the communicator may receive medical images captured by the medical device 164 (e.g., a computerized tomography (CT) device, a magnetic resonance imaging (MRI) device, and an X-ray device) through the network 150. Furthermore, the communicator may receive data such as patient diagnosis history data and treatment schedule data from the server 162, and the data may be used for diagnosing an object. In addition, the communicator may exchange data with the portable terminal 166 (e.g., doctor's or user's cellular phones, personal digital assistants (PDAs), or laptop computers) as well as the server 162 and the medical device 164 that may be disposed in a hospital. The communicator may include at least one module for communicating with external devices. Examples of the module may include a short-distance communication module, a wired communication module, and a wireless communication module. The short-distance communication module is a module for communicating with other devices located within a certain range of distance. Near field communication technology such as wireless LAN, Wi-Fi, Bluetooth, Zigbee, Wi-Fi direct (WFD), ultra wideband (UWB), infrared data association (IrDA), Bluetooth low energy (BLE), and near field communication (NFC) may be used in exemplary embodiments. However, the exemplary embodiments are not limited thereto. The wired communication module is a communication module using electric or optical signals. Examples of wired communication technology that may be used in exemplary embodiments include communication technology using pair cables, coaxial cables, or optical fiber cables, and other communication technology known to those of ordinary skill in the related art. The wireless communication module may transmit/receive wireless signals to/from at least one of a base station, an external device, and a server through a mobile radio communication network. Such wireless signals may be voice call signals, video call signals, or text/multimedia message signals, and thus may include various types of data. The X-ray apparatus 100 of FIG. 1 may include a plurality of digital signal processors (DSPs), a microprocessing unit, and a special processing circuit (such as a circuit for high-speed A/D conversion, high-speed Fourier transform, or array processing). The workstation 110 may communicate with the X-ray radiation unit 120, the high voltage generator 121, and the X-ray detector 130 by high-speed digital interfacing such as low voltage differential signaling (LVDS), an asynchronous serial communication method using a universal asynchronous receiver transmitter (UART), a synchronous communication method, a communication method based on a low delay network protocol such as controller area network (CAN), or other communication methods known to those of ordinary skill in the related art. FIG. 2A is a schematic view illustrating an exemplary X-ray apparatus 200, and FIG. 2B is a schematic view illustrating an operational state of the X-ray apparatus 200 illustrated in FIG. 2A. The X-ray apparatus 200 illustrated in FIGS. 2A and 2B is movable for taking X-ray images at any places. The X-ray apparatus 200 includes an X-ray radiation unit 220 configured to emit X-rays to an object O; an X-ray detector 130 configured to detect X-rays passing through the object O; a guide unit 230 including a guide rail 231 to guide the X-ray radiation unit 220; a main body unit 205 supporting the guide unit 230 and including an input unit 111, a controller 112, a high voltage generator 121, and a sound generator 141; and a moving unit 270 including a plurality of wheels 271 and 272 for moving the main body unit 205. The X-ray radiation unit 120 may include an X-ray source 122 configured to generate X-rays, and a collimator 123 configured to control a region on which X-rays emitted from the X-ray source 122 are incident. The X-ray detector 130 detects X-rays passing through the object O. The X-ray detector 130 may include thin film transistors (TFTs) or charged coupled devices (CCDs). The X-ray detector 130 may be placed at a particular place. For example, the X-ray detector 130 may be placed on a diagnostic table 290. After the object O is placed between the X-ray detector 130 and the X-ray radiation unit 220, the object O may be X-rayed. Instead of placing the X-ray detector 130 on the diagnostic table 290, the X-ray detector 130 may be placed at any other place as long as the X-ray detector 130 is disposed at a side of the object O opposite to the X-ray radiation unit 220. When not used, the X-ray detector 130 may be placed in a storage pocket 280 provided on the main body unit 205. When X-rays pass through the object O, some of the X-rays scatter in directions different from the incident direction of the X-rays (that is, scattering rays are generated). Such scattering rays increase in proportion to the thickness of the object O, and as scattering rays increase, the quality of X-ray images of the object O may deteriorate. Therefore, if the thickness of the object is 20 cm or greater (for example, if the object O is the chest of a patient), an X-ray grid 310 may be used to remove scattering rays by selectively transmitting X-rays. However, if the object O is a hand or foot having a relatively small thickness, image quality is not largely lowered by scattering rays, and thus X-ray images having a certain degree of quality may be obtained without using the X-ray grid 310. As described above, according to the object O to be X-rayed, an operator may determine whether to use the X-ray grid 310 together with the X-ray detector 130. To this end, the X-ray grid 310 may be configured to be easily detached from the X-ray detector 130. FIGS. 3A and 3B illustrate an X-ray grid structure 300 according to one or more exemplary embodiments. FIG. 3A illustrates the X-ray grid structure 300 separated from the X-ray detector 130, and FIG. 3B illustrates the X-ray grid structure 300 attached to the X-ray detector 130. According to the thickness of an object O, an operator may use the X-ray detector 130 after separating the X-ray grid structure 300 from the X-ray detector 130 as shown in FIG. 3A or attaching the X-ray grid structure 300 to the X-ray detector 130 as shown in FIG. 3B. FIG. 4 is an exploded perspective view illustrating the X-ray grid structure 300 of FIG. 3A. Referring to FIG. 4, the X-ray grid structure 300 includes the X-ray grid 310, and a plurality of holders 331, 332, 333, and 334 used to detachably attach the X-ray grid 310 to the X-ray detector 130. The X-ray grid 310 selectively transmits X-rays passing through an object O so that scattering rays generated when the X-rays passing through the object O may be filtered out. The X-ray grid 310 has a grating structure. The X-ray grid 310 may include an X-ray absorbing material. Examples of the X-ray absorbing material may include lead and tungsten. The X-ray grid 310 may have a polygonal shape. For example, the X-ray grid 310 may have a rectangular shape as shown in FIG. 4. However, the shape of the X-ray grid 310 is not limited thereto. That is, the X-ray grid 310 may have any other shape such as a circular shape. The X-ray grid 310 may include a rear side 3102 facing the X-ray detector 130 and a front side 3101 opposite to the rear side 3102. The X-ray grid 310 is positioned in such a manner that the front side 3101 faces an object O or the X-ray radiation unit 220 and the rear side 3102 faces the X-ray detector 130. The plurality of holders 331, 332, 333, and 334 are fixed to the X-ray grid 310 and are used to detachably attach the X-ray grid 310 to the X-ray detector 130. The holders 331, 332, 333, and 334 are fixed to portions of edges of the X-ray grid 310. The holders 331, 332, 333, and 334 are spaced apart from each other on the X-ray grid 310. For example, as shown in FIG. 4, four holders 331, 332, 333, and 334 may be disposed on corners 311, 312, 313, and 314 of the X-ray grid 310. However, the number and positions of the holders are not limited thereto. For example, as shown in FIGS. 5A to 5D, the number and positions of holders of X-ray grid structures 300a, 300b, 300c, and 300d may vary. Because the holders 331, 332, 333, and 334 are arranged on portions of the edges of the X-ray grid 310 instead of being arranged along the entire edges of the X-ray grid 310, the weights of the holders 331, 332, 333, and 334 may be light. Therefore, an operator may experience less fatigue from lifting, connecting, and disconnecting which occur when using the X-ray grid structure 300. In other words, an operator may easily attach the X-ray grid structure 300 to the X-ray detector 130. As the X-ray grid structure 300 is frequently attached and detached, this effect may be increased. When the X-ray grid structure 300 is attached to the X-ray detector 130, the holders 331, 332, 333, and 334 are pushed against the X-ray detector 130. At least one of the holders 331, 332, 333, and 334 pushed against the X-ray detector 130 may be bent in a direction crossing the attachment direction of the holders 331, 332, 333, and 334. This will be explained later in more detail with reference to FIGS. 9A to 9C. To allow bending of the holders 331, 332, 333, and 334 when the holders 331, 332, 333, and 334 are pushed against the X-ray detector 130, the holders 331, 332, 333, and 334 may include an elastic material. The elastic material may include at least one of polyurethane and silicone. Because the holders 331, 332, 333, and 334 include an elastic material, the holders 331, 332, 333, and 334 may be return to original shapes thereof after a pushing force is removed. In this manner, the X-ray grid structure 300 may be attached to the X-ray detector 130. Furthermore, because the holders 331, 332, 333, and 334 include an elastic material, the X-ray detector 130 may not be damaged by contact or friction with the X-ray grid structure 300 when the X-ray grid structure 300 is attached to the X-ray detector 130. If the holders 331, 332, 333, and 334 are formed of a hard material such as metal, the X-ray detector 130 may be scratched by friction or collision with the holders 331, 332, 333, and 334. According to one or more exemplary embodiments, the holders 331, 332, 333, and 334 may have a Shore A hardness of about 70 to about 95 i.e., as measured by a type A Shore Durometer. If the Shore A hardness of the holders 331, 332, 333, and 334 is less than about 70, the holders 331, 332, 333, and 334 may be unintentionally bent. For example, when the X-ray detector 130 to which the X-ray grid structure 300 is attached is moved, the holders 331, 332, 333, and 334 may not resist the weight of the X-ray detector 130 and may be bent. In this case, the X-ray detector 130 may be separated from the holders 331, 332, 333, and 334. On the other hand, if the Shore A hardness of the holders 331, 332, 333, and 334 is greater than about 95, the holders 331, 332, 333, and 334 may not be bent when pushed against the X-ray detector 130. In this case, the X-ray detector 130 may not be held by the holders 331, 332, 333, and 334. The holders 331, 332, 333, and 334 may have the same shape and formed of the same material. In this case, the holders 331, 332, 333, and 334 may be manufactured with high productivity. FIG. 6 is an enlarged perspective view illustrating one of the holders 331, 332, 333, and 334, and FIG. 7 is a sectional view taken along line VI-VI of FIG. 3B. Although FIG. 6 illustrates the (third) holder 333, the other holders 331, 332, and 334 may have the same shape as the holder 333 shown in FIG. 6. Referring to FIGS. 6 and 7, the holder 333 includes a fixing portion 3301 fixed to the X-ray grid 310, and a support portion 3302 extending from the fixing portion 3301 and supporting the X-ray detector 130. The fixing portion 3301 may extend in a surface direction (x-axis direction) of the X-ray grid 310. The fixing portion 3301 may be fixed to portions of edges of the X-ray grid 310. The fixing portion 3301 may be fixed to the X-ray grid 310 using an adhesive. By using an adhesive, the holder 333 may be stably fixed to the X-ray grid 310 without increasing a thickness of the holder 333 and the X-ray grid 310. In addition, the holder 333 may be stably fixed to the X-ray grid 310 without damaging or breaking the X-ray grid 310. The X-ray grid 310 may have a thickness of about 1 mm to about 2 mm. The thickness of the X-ray grid 310 is measured in a y-axis direction perpendicular to the x-axis direction. If the fixing portion 3301 is fixed to the X-ray grid 310 by other methods such as a screw coupling method, the holder 333 or the X-ray grid 310 may have to be thick, or the holder 333 may not be stably fixed to the X-ray grid 310. Furthermore, if the holder 333 is fixed to the X-ray grid 310 using a screw, when the holder 333 is bent, stress may be concentrated on a region of the X-ray grid 310 because of the screw, and thus the X-ray grid 310 may be broken. However, if the fixing portion 3301 is fixed to the X-ray grid 310 through an adhesive B which is widely applied, when the holder 333 is bent, stress may not be concentrated on a region of the X-ray grid 310, and thus the X-ray grid 310 may not be broken. For example, the adhesive B may be an epoxy-containing resin. The support portion 3302 may include a side support portion 3303 extending from the fixing portion 3301 in the y-axis direction perpendicular to the surface direction (x-axis direction) of the X-ray grid 310; and a rear support portion 3304 extending from the side support portion 3303 in the surface direction (x-axis direction) of the X-ray grid 310. The X-ray detector 130 includes a front side 1301 facing the X-ray grid 310, a rear side 1302 opposite to the front side 1301, and a lateral side 1303 between the front side 1301 and the rear side 1302. After the X-ray grid structure 300 is attached to the X-ray detector 130, the side support portion 3303 supports the lateral side 1303 of the X-ray detector 130, and the rear support portion 3304 supports the rear side 1302 of the X-ray detector 130. When the X-ray grid structure 300 is attached to the X-ray detector 130, the support portion 3302 may be pushed by the X-ray detector 130 and thus may be bent. If the pushing force applied to the support portion 3302 from the X-ray detector 130 is removed, the support portion 3302 may return to the original shape thereof. FIGS. 8A to 8C are views sequentially illustrating a process of attaching the X-ray detector 130 shown in FIG. 3A to the X-ray grid structure 300. FIGS. 9A to 9C are views illustrating the attachment process of the X-ray detector 130 of FIG. 3A based on the shape change of the holder 333. The method of attaching the X-ray grid structure 300 to the X-ray detector 130 is similar to the method of attaching the X-ray detector 130 to the X-ray grid structure 300, and thus will not be repeatedly described. Referring to FIG. 8A, the X-ray detector 130 and the X-ray grid structure 300 are prepared. The function of the X-ray detector 130 is to detect X-rays emitted from the X-ray radiation unit 120 and passing through an object O. A battery may be attached to the X-ray detector 130 through a cover 135. The X-ray grid structure 300 includes the X-ray grid 310, and the plurality of holders 331, 332, 333, and 334 (e.g., first to fourth holders 331, 332, 333, and 334) fixed to the corners of the X-ray grid 310. Referring to FIG. 8B, a first corner 131 and a second corner 132 of the X-ray detector 130 are inserted into the first and second holders 331 and 332. In this state, the X-ray detector 130 is moved so that a third corner 133 and a fourth corner 134 of the X-ray detector 130 may approach the third and fourth holders 333 and 334. Then, the third and fourth corners 133 and 134 of the X-ray detector 130 are brought into contact with the third and fourth holders 333 and 334. In this state, if the X-ray detector 130 is pushed toward the X-ray grid 310 in an attachment direction F1, the holders 331, 332, 333, and 334 are bent in directions crossing the attachment direction F1, and the X-ray detector 130 is attached to the X-ray grid structure 300. Referring to FIG. 8C, after the X-ray detector 130 is attached to the X-ray grid structure 300, the lateral side 1303 of the X-ray detector 130 is supported by the side support portions 3303 of the holders 331, 332, 333, and 334, and the rear side 1302 of the X-ray detector 130 is supported by the rear support portions 3304 of the holders 331, 332, 333, and 334. With reference to FIGS. 9A to 9C, an explanation will now be given of the change of the holder 333 when the X-ray detector 130 is attached to the X-ray grid structure 300. Referring to FIG. 9A, as the X-ray detector 130 is moved toward the X-ray grid 310, the front side 1301 of the X-ray detector 130 is brought into contact with the rear support portion 3304 of the holder 333. Referring to FIG. 9B, as the X-ray detector 130 is pushed toward the X-ray grid 310 in the attachment direction F1, the support portion 3302 is bent in a direction C1 crossing the attachment direction F1. The X-ray detector 130 is pushed in the attachment direction F1 in a state in which the lateral side 1303 of the X-ray detector 130 makes contact with the rear support portion 3304. Referring to FIG. 9C, as the X-ray detector 130 is further pushed, the X-ray detector 130 is moved closer to the X-ray grid 310, and the contact of the lateral side 1303 of the X-ray detector 130 and the rear support portion 3304 ends. As a result, a pushing force applied from the X-ray detector 130 to the rear support portion 3304 is removed, and the rear support portion 3304 returns (in a direction C2) to an original position thereof. Then, the rear support portion 3304 supports the rear side 1302 of the X-ray detector 130, and the side support portion 3303 supports the lateral side 1303 of the X-ray detector 130. In this way, the attachment of the X-ray detector 130 to the X-ray grid structure 300 is completed as shown in FIG. 8C. Referring again to FIG. 9A, the rear support portion 3304 may have a length L1 of about 3 mm to about 6 mm. If the length L1 of the rear support portion 3304 is smaller than about 3 mm, the rear support portion 3304 may not sufficiently support the X-ray detector 130. On the other hand, if the length L1 of the rear support portion 3304 is greater than about 6 mm, when the X-ray detector 130 is attached, the end of the rear support portion 3304 may be bent in the attachment direction F1 of the X-ray detector 130 and may be inserted between the lateral side 1303 of the X-ray detector 130 and the side support portion 3303. The rear support portion 3304 may have a slope 3304S having an outwardly increasing height. When the rear support portion 3304 is brought into contact with the X-ray detector 130 and pushed by the X-ray detector 130, the slope 3304S of the rear support portion 3304 makes contact with the X-ray detector 130 so that the rear support portion 3304 may be smoothly moved in the direction C1 while being pushed by the X-ray detector 130. In the above-described embodiments, the holders 331, 332, 333, and 334 are fixed to the X-ray grid structure 310 by using the adhesive B. However, the holders 331, 332, 333, and 334 may be fixed to the X-ray grid structure 310 by using another method. FIG. 10 is an exploded perspective view illustrating a modified example of the X-ray grid structure of FIG. 3A, according to another exemplary embodiment. FIG. 11A is an enlarged view of a portion illustrated in FIG. 10, and FIG. 11B is a view of the portion from a different angle. Referring to FIG. 10, an X-ray grid structure 300-1 includes an X-ray grid 310-1, and a plurality of holders 331-1, 332-1, 333-1, and 334-1 used to detachably attach the X-ray grid 310-1 to the X-ray detector 130. The same description as that given in the previous exemplary embodiments will not be repeated, and differences will be mainly described below. Referring to FIGS. 11A and 11B, each of the holders 331-1, 332-1, 333-1, and 334-1 includes a first member 3401 contacting a rear side 3101 of the X-ray grid 310-1, a second member 3402 contacting a front side 3102 of the X-ray grid 310-1, and coupling members 3403 fastening the first member 3401 and the second member 3402. Hereinafter, the holder 332-1 of the holders 331-1, 332-1, 333-1, and 334-1 will be mainly described for clarity of illustration. The first member 3401 includes a plurality of coupling hole structures 3404 for coupling with the coupling members 3403. The coupling hole structures 3404 protrude toward the second member 3402. The first member 3401 may further include guide protrusions 3405 for determining the positions of the second member 3402. The guide protrusions 3405 may be arranged between the coupling hole structures 3404. The X-ray grid 310-1 may include openings h1 and h2 for receiving the coupling hole structures 3404 and the guide protrusions 3405 of the first member 3401. The coupling members 3403 include body portions 3403B for coupling with the coupling hole structures 3404 of the first member 3401, and head portions 3403H for pressing the second member 3402. Diameters of the head portions 3403H are greater than diameters of the body portions 3403B. The second member 3402 includes connection holes 3406 which receive the coupling members 3403 and are connected to the coupling hole structures 3404 of the first member 3401. The connection holes 3406 include support grooves 3407 to support the head portions 3403H of the coupling members 3403. FIG. 12A is a cross-sectional view of the portion illustrated in FIG. 11B, and FIG. 12B is a cross-sectional view illustrating a state in which the first and second members 3401 and 3402 of the holder 332-1 illustrated in FIG. 12A are coupled to each other using the coupling members 3403 and thus the holder 332-1 is fixed to the X-ray grid 310-1. Referring to FIGS. 12A and 12B, the first member 3401 of the holder 332-1 supports the rear side 3101 of the X-ray grid 310-1, and the second member 3402 of the holder 332-1 supports the front side 3102 of the X-ray grid 310-1. In this state, if the coupling members 3403 are coupled, the X-ray grid 310-1 is pressed by the first member 3401 and the second member 3402. In this way, the holder 332-1 is fixed to the X-ray grid 310-1. The first member 3401 and a portion of the second member 3402 may correspond to the fixing portion 3301 described in the previous embodiments, and a remaining portion of the second member 3402 may correspond to the support portion 3302 described in the previous exemplary embodiments. The body portions 3403B of the coupling members 3403 include threaded regions 3403B1 inserted into the coupling hole structures 3404 and screwed to the coupling hole structures 3404. When the threaded regions 3403B1 of the coupling members 3403 are moved toward the first member 3401 while being screwed to the coupling hole structures 3404, the second member 3402 is pressed at the support grooves 3407 by the heads 3402H of the coupling members 3403. The body portions 3403B of the coupling members 3403 may include non-threaded regions 3403B2 on which threads are not formed. When the coupling members 3403 are coupled, the coupling members 3403 are not screwed to the connection holes 3406 of the second member 3402. Therefore, the second member 3402 may not be deteriorated by heat generated during screw coupling and may not be deformed by pressure applied from the coupling members 3403 during screw coupling. At least a portion of the second member 3402 may include an elastic material so as to be bent when being pressed by the X-ray detector 130. The elastic material may include one or more of polyurethane and silicone. FIG. 13 is a view illustrating a state in which the X-ray detector 130 is attached to the X-ray grid structure 300-1. Referring to FIG. 13, when the X-ray detector 130 is moved close to the X-ray grid 310-1 of the X-ray grid structure 300-1, a portion 3304 of the second member 3402 may be elastically deformed, and then the X-ray detector 130 may be attached to the X-ray grid structure 300-1. Referring back to FIG. 12A, the first member 3401 may include a material that is different from a material included in the second member 3402. For example, the first member 3401 may have a bending strength greater than that of the second member 3402. The bending strength may be considered as an elastic deformation force. It may be relatively difficult to elastically deform the first member 3401 compared to the case of elastically deforming the second member 3402. In this case, the first member 3401 may be easily coupled to the coupling members 3403. For example, the first member 3401 may include a plastic material or a metallic material as a material having a bending strength greater than that of the second member 3402. Examples of the plastic material may include polycarbonate, an acrylonitrile-butadiene-styrene (ABS) resin, and polyethylene. Examples of the metallic material may include stainless steels (STSs), carbon steels for mechanical structures, aluminum alloys, and cold-rolled steels (SPCC). Examples of the carbon steels for mechanical structures may include SM45C and SM25C specified in Korean Industrial Standards (KS), and examples of the aluminum alloys may include AL6061 and AL6064 specified in KS. The first member 3401 may make contact with an object O to be X-rayed. Since the first member 3401 includes a plastic material or a metallic material, friction between the first member 3401 and the object O may be relatively low when compared to friction between an elastic material and the object O. Therefore, the object O may experience less inconvenience. In the previous embodiments, it is described that all of the holders 331-1, 332-1, 333-1, and 334-1 are plastically deformable. However, the holders 331-1, 332-1, 333-1, and 334-1 are not limited thereto. For example, some of the holders 331-1, 332-1, 333-1, and 334-1 may be rigid bodies that are not elastically deformable. FIG. 14 illustrates an X-ray grid structure 300A according to another exemplary embodiment. The X-ray grid structure 300A shown in FIG. 14 is constructed by attaching reinforcement films 326 and 327 to the X-ray grid 310 shown in FIG. 4, and other structures of the X-ray grid structure 300A are the same as those of the X-ray grid structure 300 shown in FIG. 4. Thus, descriptions of the same structures will not be repeated, and the following description of the X-ray grid structure 300A will be focused on different structures. The reinforcement films 326 and 327 may be disposed on the front side and rear side of an X-ray grid 310A. The reinforcement films 326 and 327 may reinforce the X-ray grid 310A and the X-ray grid structure 300A. In the X-ray grid structure 300A of the current exemplary embodiment, because the X-ray grid 310A is not reinforced by holders 331, 332, 333, and 334, the reinforcement films 326 and 327 may be used to protect the X-ray grid 310A. Because the reinforcement films 326 and 327 are disposed on the front and rear sides of the X-ray grid 310A, the X-ray grid 310A may not be broken even though the X-ray grid 310A is bent in any direction when being attached to or detached from the X-ray detector 130. The reinforcement films 326 and 327 may be formed of carbon fiber. Because carbon fiber has a high x-ray transmittance, the x-ray transmittance of the X-ray grid 310A may not be lowered by the reinforcement films 326 and 327. Referring FIG. 7, the fixing portion 3301 may include a slope 3301S having a height increasing in an outward direction of the X-ray grid 310. FIG. 15 schematically illustrates an arrangement in which the X-ray detector 130 coupled with the X-ray grid structure 300 is disposed on the diagnostic table 290 so as to explain the function of the slope 3301S of the fixing portion 3301. Referring to FIG. 15, the X-ray detector 130 to which the X-ray grid structure 300 is attached is positioned so that the X-ray grid 310 faces an object O. In this arrangement, X-rays passing through the object O are incident on the X-ray detector 130 through the X-ray grid 310. The object O is on the X-ray grid structure 300, and the fixing portions 3301 of the holders 331, 332, 333, and 334 may make contact with the object O. In this case, because the slopes 3301S of the fixing portions 3301 make contact with the object (O), the object (O) may feel less discomfort. In addition, surfaces of the fixing portions 3301 of the holders 331, 332, 333, and 334 contacting the object O may be smoothened so as to further reduce any discomfort that the object O may feel. For example, the fixing portions 3301 may include a plastic material or may be coated with a plastic film. FIG. 16 is a plan view illustrating the X-ray detector 130 to which the X-ray grid structure 300 shown in FIG. 4 is attached. Referring to FIGS. 4 and 16, grooves 321, 322, 323, and 324 may be formed in the edges E1 of the X-ray grid 310. The height h1 and width w1 of the X-ray grid 310 may be smaller than the height h2 and width w2 of the X-ray detector 130, respectively. The edges E1 of the X-ray grid 310 may be positioned inside the edges E2 of the X-ray detector 130, and the X-ray grid 310 may be prevented from protruding outward from the X-ray detector 130. This structure may prevent an operator from unstably holding only the X-ray grid 310. FIG. 17 is a cross-sectional view taken along line XVII-XVII of FIG. 16. Referring to FIG. 17, the edge E1 of the X-ray grid 310 is positioned inside the edge E2 of the X-ray detector 130. Because the X-ray grid 310 is thinner than the X-ray detector 130 is disposed inside the X-ray detector 130, an operator may hold the X-ray grid 310 together with the X-ray detector 130. If the edges E1 of the X-ray grid 310 are disposed outside or aligned with the edges E2 of the X-ray detector 130, an operator may hold only the X-ray grid 310. In this case, because the X-ray detector 130 is held by only the holders 331, 332, 333, and 334, the holders 331, 332, 333, and 334 may be bent due to the weight of the X-ray detector 130, and thus the X-ray detector 130 may be separated from the holders 331, 332, 333, and 334. However, according to the exemplary embodiment, the edges E1 of the X-ray grid 310 are disposed inside the edges E2 of the X-ray detector 130. Therefore, when an operator holds the X-ray detector 130 to which the X-ray grid structure 300 is attached, the operator may not only hold the X-ray grid 310. Reference numerals are used in the accompanying drawings to provide clear understanding of the exemplary embodiments, and terms used in the descriptions of the exemplary embodiments should not be construed as being limited to general meanings or dictionary definitions but should be construed as including all elements that those of ordinary skill in the related art may associate with the terms. In addition, the above-described operations or exemplary embodiments are examples which are not intended to limit the scope and spirit. In the present disclosure, descriptions of known electric components, control systems, software, and other functional aspects thereof may not given for conciseness. Furthermore, in the drawings, connection lines or members between elements are exemplary functional, physical, and/or electric connections that can be replaced with or used together with other functional, physical, and/or electrical connections. In the present disclosure, terms such as “comprising” and “including” should be construed as open-ended terms that do not exclude the presence or addition of one or more other elements. In the present disclosure, examples or exemplary terms (for example, “such as” and “etc.”) are used for the purpose of description, and thus the scope and spirit are not limited to the examples or exemplary terms unless limited by the claims. Furthermore, it will be understood by those of ordinary skill in the art that various changes in form and details may be made within the exemplary embodiments without departing from the spirit and scope as defined by the following claims.
051868687	summary	TECHNICAL FIELD This invention involves agents useful for preparing isotopically labeled compounds. More particularly, it relates to novel site-selective deuterating and tritiating agents with high deuterium or tritium contents, methods for their preparation, and methods for using these agents to insert high levels of deuterium/tritium labels into reducible compounds. BACKGROUND ART Isotopic labeling is a useful tool for rendering organic compounds easily identifiable in analytical and biochemical schemes. The isotopic label may be detected very sensitively, especially in the case of a radionuclide. By placing the isotopic label in a specific site in a molecule, it is possible to study reactions involving the molecule and detect and delineate reaction paths. Traditionally, isotopic hydrogen (e.g., tritium or deuterium) labeling has been limited by the unavailability of adequate deuterating/tritiating agents. There are two fundamental techniques for introducing isotopic hydrogen into organic molecules. These are synthetic techniques and exchange techniques. Synthetic techniques, where tritium or deuterium is directly and specifically inserted, yield high tritium or deuterium abundance, but are limited by the chemistry required. In addition, the molecule being labeled may be changed, depending upon the severity of the synthetic reaction employed. Exchange techniques yield lower tritium or deuterium incorporation, often with the isotope being distributed over many sites on the molecule, but offer the advantage that they do not require separate synthetic steps and are less likely to disrupt the structure of the molecule being labeled. Three common synthetic methods for incorporating activity levels of tritium into target molecules have been: (1) "hydrogenation" of the target molecule using tritium gas (T.sub.2), with a catalyst; (2) tritiodehalogenation; and (3) tritiomethylation with CT.sub.3 I. Each of these methods has been heavily employed in the art to achieve high levels of isotope incorporation, yet each involves reaction conditions that can affect the integrity of the target molecule. Conversely, the use of milder "tritium exchange" methods typically involves reduction in the level of tritium incorporated into the target molecule. A fourth way of synthetically incorporating tritium into a target molecule which contains a reducible site is to contact the target molecule with a reducing agent which is capable of inserting one or more tritium atoms into the reducible site. This methodology essentially mimics reduction with hydrogen-inserting reducing agents. Metal borohydrides such as LiAlH.sub.4 and NaBH.sub.4 are widely used mild reducing agents. In contrast, lithium trialkylborohydride (superhydride) (Brown, H. C. et al., (1980) J. Org. Chem. 45:1-12) is known to be a highly reactive nucleophilic reducing agent, and is now commonly used in organic synthesis (Brown, H.C. et al., (1979) Aldrichimica Acta 12:3-11). This reagent is capable of reducing esters, hindered alkyl halides (Brown, H.C. et al., (1973) J. Am. Chem. Soc. 95: 1669-1671) and toluene-p-sulphonates, in addition to exhibiting great sterioselectivity and steriospecificity, as in the reduction of epoxides. More hindered trialkylborohydrides (such as lithium or potassium tri-sec-butyl borohydride; known as L-selectride and K-selectride) exhibit even more steric control, as in the reduction of cyclic ketones (Fortunator, J. M. et al., (1975) J. Org. Chem. 41: 2194-2200). These remarkable hydride reducing agents are generally synthesized by reaction of the appropriate alkylborane with a metal hydride (Brown, H. C. et al (1980) J. Org. Chem. 45:1-12). It is clear that the ability to produce metal deuterides and tritides with high deuterium/tritium content would give access to a large number of deuteriated/tritiated reducing agents for chemoselective, regioselective and stereoselective labeling sequences, and allow high level deuterium/tritium incorporation through established synthetic routes with these highly reactive and selective reagents. The utility of supertritide has been demonstrated (Hegde, S. et al., (1983) J. Chem. Soc. Chem. Commun., 1484-1485) by the reduction of acids, aldehydes, toluene-p-sulphonates and epoxides, but these reactions were conducted with supertritide of specific activities in the mCi/mmol range (100's of MBq/mmol). Later work (Coates, R. M. et al., (1986) Synthesis and Applications of Isotopically Labeled Compounds (Proc. 2nd Int. Symp.), 207-212) reported the synthesis of chiral methyl groups, starting with supertritide at approximately 3 Ci/mmol. This is still a factor of 10 below the theoretical maximum (one tritium atom per molecule gives a specific activity 28.72 Ci/mmol or 1063 GBq/mmol) and consequently this tritiation reagent has not been applied in those types of reactions where it is used in general chemistry. The same general statements are true for the availability and utility of LiAlT.sub.4. At this time, both LiAlD.sub.4 and LiEt.sub.3 BD are available commercially. Although the complex hydrides are very useful reagents, the preparation of the initial metal hydrides has been problematic, especially where radioisotopes are involved. Metal hydrides may be prepared from the respective elements: e.g. atomic hydrogen produced in a glow discharge tube was found to rapidly react with various alkali metals, vacuum condensed as thin films on the reaction tube walls, to form metal hydrides (Ferrell, E. et al., (1934) J. Chem. Soc. 7-8). Other means of producing atomic hydrogen (or tritons) include dissociation of molecular hydrogen (tritium) by microwave discharge activation (Cao, G. Y. et al., (1984) Trans. Am. Nucl. Soc. 45:18-19) or on the surface of a hot tungsten wire (Moser, H. C. et al., (1962) J. Chem. Phys. 66:2272-2273). The latter two methods offer the advantages of being less limiting in scale and the option of exchange of tritons with LiH, thereby avoiding the use of liquid lithium. Tritide synthesis on a large scale has also been reported under conditions of high temperature and pressure, where lithium tritide was synthesized at 98% purity in an iron crucible at 750.degree. C., in the presence of three atmospheres of tritium gas (Bowman, R. C. et al., (1988) J. Nucl. Materials 154:318-331). The severe conditions and need for excessive tritium in this procedure make this option less attractive than the others outlined above, and only usable by the nuclear/fusion industries. One other problem lies in the fact that once the hydride (deuteride or tritide) is formed by one of the above methods its chemical reactivity is reported to be low, and conversion into a complex hydride for use as a reducing reagent in organic synthesis may be sluggish. Hegde, S. et al., (1983) J. Chem. Soc. Chem. Commun., 1484-1485, reported that a typical reduction with such agents took several days at 150.degree. C. The present invention is directed to the aforementioned problems. It provides a new method of in situ synthesis to generate a highly reactive alkali metal deuteride or tritide with a large proportion of its hydrogen present as deuterium or tritium from the respective deuterium or tritium gas. This material is then converted into a desirable highly selective labeling agent. DESCRIPTION OF THE PRIOR ART Background References. Brown, H. C. and Krishnamurthy, S., (1979) Aldrichimica Acta 12:3-11 presents a good summary of the state of borane chemistry for organic reductions, including the increased ability to perform regioselective, stereoselective and chemoselective reductions of various organic functional groups. Selective Borohydride Reducing Agents. The synthesis of Superhydride is described in Brown, H. C. et al., (1980) J. Org. Chem. 45:1-12, and some of its uses are described in Brown, H. C. and Krishnamurthy, S., J. (1973) Am Chem. Soc. 95:1669-1671. L-Selectride and K-Selectride are described synthetically in Brown, H. C. et al., (1978) J. Am. Chem. Soc. 100:3343, and some of their uses are described in Fortunato, J. M. and Ganem, B. (1976) J. Org. Chem. 41: 2194-2200, and Brown, H. C. and Dickason, W. C., (1970) J. Am. Chem. Soc. 92:709. Tritium Labeling Agents. The synthesis of a low specific activity "Supertritide" (LiEt.sub.3 BT) is described in Hegde, S. et al., (1983) J. Chem. Soc., Chem. Comm. 1983:1484-1485, and see Coates, R. M. et al., in "Synthesis and Applications of Isotopically Labeled Compounds (Proc 2d Int'l Symp.)". pp. 207-212 Muccino, R. R., ed. (Elsevier Press: Amsterdam) (1986). Altman, L. J. and Thomas, L., (1980) Anal. Chem. 52:992-995 identified a high specific activity sodium borotritide (NaBT.sub.4). Reactive Lithium Hydride. Klusener, P. et al., (1986) Angew. Chem. (English Edition) 25:465, and Pi, R. et al., (1987) J. Org. Chem. 52:4299-4303 have reported a method of in situ synthesis of lithium hydride by bubbling hydrogen gas through a solution of n-butyllithium in hexane in the presence of tetramethylethylenediamine (TMEDA). The resulting hydride is a fine suspension and is highly reactive at room temperature. RELATED PUBLICATIONS In November of 1989, the present inventors and a colleague published a report of some of the work described herein in Trans. Am. Nucl. Soc. 60:34-36 (1989). SUMMARY OF THE INVENTION It is accordingly a primary object of the present invention to overcome the disadvantages of the prior art and to provide methods and reagents which are capable of tritium and deuterium labeling selected specific sites in target molecules, while achieving the labeling at high levels of tritium and deuterium insertion. Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following, or may be learned by practice of the invention. The process of the invention is characterized as involving the in situ generation of highly selective reducing agents from alkali metal tritides or deuterides which have in turn formed from alkali metal alkyls. Thus, in one aspect, the invention provides a process for introducing tritium or deuterium label into organic compounds having a reducible site. This process involves reacting an organic solvented solution of an alkali metal alkyl with a gas which contains tritium or deuterium in the presence of an alkyl tertiary amine. This gives rise to an alkali metal tritide or deuteride. This tritide or deuteride can then be reacted in any of several manners to give rise to a reactive labeling reducing agent. In one of these subsequent reactions the alkali metal tritide or deuteride is reacted with a solution of trialkylborane thereby forming an alkali metal trialkyl borotritide or borodeuteride which can serve as the reducing agent. In another of the subsequent reactions the alkali metal tritide or deuteride is reacted with a solution of aluminum halide thereby forming a solution of alkali metal aluminum tritide or deuteride reducing agent. In a third such reaction the alkali metal tritide or deuteride is reacted with boron trifluoride thereby forming the tritium or deuterium analog of borane which can also serve as a selective reducing agent. Each of these reducing agents can then be contacted with the organic compound having the reducible site so as to directly reduce the reducible site and introduce tritium or deuterium atoms thereinto. In another aspect this invention provides the highly specific and selective deuterium and tritium labeling reagents just described, that is, the tritium and deuterium analogs of alkali metal trialkyl borohydride, the tritium and deuterium analogs of alkali metal aluminum hydride, and the deuterium and tritium analogs of borane. In particularly preferred embodiments the process and reagents provided by this invention are used at very high specific activities, often approaching the theoretical maximum. Thus, this invention can provide highly specific reagents and a process for achieving high levels of deuterium and tritium in selected sites of sensitive organic compounds.
	claims	1. A method for measuring flow rate within a volume comprising:transmitting, by a transmission device, a first signal through fluid contained within the volume, wherein the volume is bounded, at least in part, by an interior surface of an outer structure and an object at least partially located within the outer structure, wherein the transmission device is located at a first location on the outer structure;measuring a first time of flight of the first signal from the first location to a second location on the outer structure;propagating a second signal through the fluid from the second location to a third location on the outer structure;measuring a second time of flight of the second signal; anddetermining the flow rate of the fluid within the volume based, at least in part, on both the first time of flight and the second time of flight. 2. The method of claim 1, wherein the first signal travels through the fluid along a substantially linear path that passes between the object and the interior surface of the outer structure before arriving at the second location. 3. The method of claim 2, wherein the second signal travels through the fluid along a substantially linear path that passes between the object and the interior surface of the outer structure before arriving at the third location, and wherein the method further comprises:transmitting one or more additional signals through the fluid along a substantially linear path; andaggregating a plurality of the linear paths as a combined signal path that passes around the object. 4. The method of claim 3, wherein the combined signal path passes completely around the object. 5. The method of claim 2, wherein the object comprises a cylindrically shaped surface, and wherein the volume comprises an annular region formed between the cylindrically shaped surface of the object and the interior surface of the outer structure. 6. The method of claim 1, wherein determining the flow rate of the fluid within the volume comprises taking an average of the first time of flight and the second time of flight. 7. The method of claim 1, wherein determining the flow rate of the fluid within the volume comprises taking a weighted average of the first time of flight and the second time of flight to account for structural interference to the flow of the fluid within the volume. 8. The method of claim 1, further comprising comparing the first time of flight with the second time of flight to identify irregularities in flow rate of the fluid through the volume. 9. The method of claim 8, further comprising identifying a cold slug of the fluid within the volume based, at least in part, the comparison of the first time of flight with the second time of flight. 10. The method of claim 1, further comprising determining a temperature of the fluid based, at least in part, on an average of the first time of flight and the second time of flight. 11. An apparatus for measuring flow rate within a volume, comprising:means for transmitting a first signal through fluid contained within the volume, wherein the volume is bounded, at least in part, by an interior surface of an outer structure and by an object at least partially located with the outer structure, wherein the means for transmitting is located at a first location on the outer structure;means for measuring a first time of flight of the first signal from the first location to a second location on the outer structure;means for propagating a second signal through the fluid from the second location to a third location on the outer structure, wherein a second time of flight is measured for the second signal; andmeans for determining the flow rate of the fluid within the volume based, at least in part, on both the first time of flight and the second time of flight. 12. The apparatus of claim 11, wherein the means for propagating is located at the second location on the outer structure. 13. The apparatus of claim 12, wherein the means for propagating comprises a means for transmitting the second signal through the fluid. 14. The apparatus of claim 13, wherein the means for propagating further comprises means for receiving the first signal, and wherein the means for transmitting the second signal and the means for receiving the first signal are co-located at the second location on the outer structure. 15. The apparatus of claim 14, wherein the second signal is transmitted to the third location in response to the first signal being received by the means for receiving. 16. The apparatus of claim 12, wherein the means for propagating comprises means for reflecting the first signal to propagate the second signal. 17. The apparatus of claim 11, wherein the outer structure is associated with an overall length through which the fluid flows, and wherein the first location, the second location, and the third location are associated with different longitudinal positions along the overall length of the outer structure, and wherein both the first signal and the second signal travel along a signal path formed at a non-perpendicular angle with respect to the flow of the fluid through the volume. 18. The apparatus of claim 11, wherein the first signal and the second signal travel along at least a portion of a signal path formed between the first location and the third location, and wherein the means for transmitting and the means for propagating are positioned on the outer structure so that the signal path avoids the object. 19. A system for measuring flow rate within a volume, comprising:a first transmission device configured to transmit a first signal through fluid contained within the volume, wherein the volume is bounded, at least in part, by an interior surface of an outer structure and by an object at least partially contained within the outer structure, and wherein the first transmission device is located at a first location on an exterior surface of the outer structure so as to transmit the first signal while avoiding the object;a processing device configured to measure a first time of flight of the first signal from the first location to a second location on the exterior surface of the outer structure; anda second transmission device located at the second location and configured to transmit a second signal through the fluid from the second location to a third location on the exterior surface of the outer structure while avoiding the object, wherein the processing device is further configured to measure a second time of flight for the second signal, and wherein the flow rate of the fluid within the volume is determined based, at least in part, on both the first time of flight and the second time of flight. 20. The system of claim 19, further comprising a receiving device co-located with the second transmission device at the second location, wherein the first transmission device and the receiving device are associated with different longitudinal positions along the overall length of the outer structure, and wherein the second transmission device is configured to transmit the second signal in response to the receiving device having received the first signal.
	description	This is a Continuation of International Application PCT/EP2008/000842, with an international filing date of Feb. 2, 2008, which was published under PCT Article 21(2) in English, and the complete disclosure of which is incorporated into this application by reference. The present invention relates to a reflective optical element for an operating wavelength in the extreme ultraviolet and soft x-ray wavelength range, in particular for use in EUV lithography devices, which has a multilayer system made of at least two alternating materials having different real parts of the index of refraction at the operating wavelength. Furthermore, the present invention relates to a projection system and an illumination system, in particular for an EUV lithography device, having at least one reflective optical element and to an EUV lithography device having at least one reflective optical element. Reflective optical elements for the extreme ultraviolet (EUV) and soft x-ray wavelength range (e.g., wavelengths between approximately 1 nm and 20 nm) such as photomasks or multilayer mirrors, are used in particular in the lithography of semiconductor components. Because EUV lithography devices typically have multiple reflective optical elements, they must have the highest possible reflectivity to ensure a sufficiently high total reflectivity. Because typically multiple reflective optical elements are situated one behind another in an EUV lithography device, even small reflectivity losses at each individual reflective optical element have a greater effect on the total reflectivity. Reflective optical elements for the EUV and soft x-ray wavelength range typically have multilayer systems. These are alternatingly applied layers of a material having a higher real part of the index of refraction at the operating wavelength (also called a spacer) and a material having a lower real part of the index of refraction at the operating wavelength (also called an absorber), an absorber-spacer pair forming a stack. A crystal is thus simulated in a certain way, whose lattice planes correspond to the absorber layers at which Bragg reflection occurs. The thicknesses of the individual layers and also of the repeating stack may be constant or also vary over the entire multilayer system, depending on which reflection profile is to be achieved. One approach for ensuring the highest possible total reflectivities in EUV lithography devices is to provide reflective optical elements with a protective layer of one or more layers, to protect the reflective optical elements from contamination. The service life of the reflective optical elements is thus lengthened and a reflectivity loss over time is reduced. A further approach supplements the basic structure made of absorber and spacer with further more and less absorbent materials to increase the maximum possible reflectivity at the particular operating wavelength. For this purpose, in many stacks, absorber and/or spacer materials may be exchanged with one another or the stack may be constructed from more than one absorber and/or spacer material. The absorber and spacer materials may have constant or also varying thicknesses over all stacks to optimize the reflectivity. In practice, higher reflectivities cannot be achieved to the expected extent in reflective optical elements having complex material sequences. It is an object of the present invention to provide a reflective optical element which provides the highest possible reflectivity at its operating wavelength. This object is achieved, in one formulation of the invention, by a reflective optical element for an operating wavelength in the soft x-ray and extreme ultraviolet wavelength range, e.g. for use in an EUV lithography device, which has a multilayer system with respective layers of at least two alternating materials having differing real parts of the index of refraction at the operating wavelength, and with at least two additional layers of further material each being situated adjoining at least one of the two alternating materials, in particular on at least one transition between the two alternating materials. The materials and/or further materials may include either identical or differing compositions, as described in greater detail below. This object is achieved, in another formulation, by a corresponding reflective element, in which a first additional layer of a further material is situated on at least one transition between the two alternating materials, which results in an increase of the maximum reflectivity of the multilayer system at the operating wavelength compared to the reflectivity without the additional layer, and a second additional layer of another further material is situated on the transition, which acts as a barrier between the adjoining layers, with the first and second additional layer. The basic structure of this multilayer system with the first and second additional layer is based on the finding that many materials which are capable of increasing the reflectivity react chemically with the basic materials of the multilayer system, in particular the spacer material, so that additional layers of undesired material form, which on one hand have a negative effect on the reflectivity because of their index of refraction at the operating wavelength, and, on the other hand, result in a shift of the phase angle of the electromagnetic wave in relation to the interfaces and thus in a reduction of the reflectivity at the operating wavelength due to spatial shift of the interfaces between absorber and spacer layers. Particularly in the EUV and soft x-ray wavelength range, metals are suitable as the absorber layer and nonmetals, which frequently react with metals, are suitable as the spacer layer. By simultaneously considering two intermediate layers, namely a reflection-enhancing intermediate layer and an intermediate layer which prevents chemical interaction and/or diffusion between the reflection-enhancing intermediate layer and the adjoining spacer or possibly also absorption layer like a barrier, the reflectivity of the starting multilayer system of real reflective optical elements made of the absorption and the spacer materials may be increased. Materials which do not significantly reduce the reflectivity gains from the first intermediate layer are especially preferred for the second intermediate layer, materials which result in an additional reflectivity gain are very especially preferred. This object is further achieved, in yet another formulation, by a corresponding reflection element in which the two additional layers differ from one another at a transition from the material having a lower real part of the index of refraction to the material having a higher real part of the index of refraction than at a transition from the material having a higher real part of the index of refraction to the material having a lower real part of the index of refraction. It has been found that having different additional layers at different transitions leads to a higher reflectivity of the resulting multilayer system at the operating wavelength. In reflective optical elements in which the multilayer system has a protective layer on the side which is subjected to the EUV or soft x-ray radiation in operation, a first additional layer of a further material is advantageously situated on the transition between multilayer system and protective coating, which results in an increase of the maximum reflectivity at the operating wavelength in comparison to the reflectivity without the additional layer, and a second additional layer of another further material is situated, which acts as a barrier between the adjoining layers. Moreover, this object is achieved, in yet a further formulation, by a projection system, in particular for an EUV lithography device, having at least one such reflective optical element, by an illumination system, in particular for an EUV lithography device, having at least one such reflective optical element, and by an EUV lithography device having at least one such reflective optical element. Advantageous embodiments are found in the dependent claims. FIGS. 1a,b show an example of a reflective optical element 1 for the extreme ultraviolet and soft x-ray wavelength range, in particular for use in EUV lithography devices, e.g., as a photomask or as a mirror. FIG. 1a schematically shows the higher-order structure of the multilayer system 2. The multilayer system 2 has been produced in the present example by successively coating a substrate 3 using different materials having different complex indices of refraction. Moreover, a protective layer 4 was additionally applied to the multilayer system 2 for protection from external influences such as contamination. The protective layer 4 itself may be composed of multiple different material layers, which are inert to various contamination influences, suppress a chemical interaction with the multilayer system 2, and ensure an optical adaptation to the multilayer system 2, for example, to influence the optical properties such as the reflectivity of the reflective optical system 1 as little as possible. The multilayer system 2 includes multiple repeating stacks 20, whose structure is schematically shown in FIG. 1b. The layers of a stack 20, which particularly result in reflection at an operating wavelength due to the multiple repetition of the stacks 20, are generally designated absorber layers 22 and are made of a material having a lower real part of the index of refraction and the so-called spacer layers 21 made of a material having a higher real part of the index of refraction. Thus, a crystal is in a way simulated, the absorber layers 22 corresponding to the lattice planes within the crystal, which have a distance to one another defined by the particular spacer layers 21 and at which reflection of incident EUV and/or soft x-ray radiation occurs. The thicknesses of the layers are selected such that at a specific operating wavelength, the radiation reflected at each absorber layer 22 constructively superimposes, to thus achieve maximum reflectivity of the reflective optical element. In the present example illustrated in FIG. 1b, a first intermediate layer 23a,b to increase the maximum reflectivity in relation to the basic reflectivity, which would result if only the spacer layers 21 and the absorber layers 22 were provided, i.e. the theoretically maximum possible reflectivity of the stack 20 is increased, is provided both at the interface between absorber layer 22 on spacer layer 21 and also at the interface between spacer layer 21 on absorber layer 22. A second intermediate layer 24a,b is provided, which acts as a barrier between the first intermediate layer 23a,b and, in the present example, of the adjoining spacer layer 21 against chemical interaction or diffusion, advantageously against both. It is to be noted that it is also possible to provide the two intermediate layers 23a,b, 24a,b at only one of the two interfaces between absorber layer 22 and spacer layer 21 or between spacer layer 21 and absorber layer 22. It is also possible to provide two second intermediate layers 24a,b on both sides of the first intermediate layer 23a,b to thus suppress a chemical interaction and/or diffusion both with the spacer layer 21 and also with the absorber layer 22, as is schematically illustrated in FIG. 1c. The second intermediate layers 24a, 24b, 24a′, 24b′ on either side of some first intermediate layers 23a, 23b may be different with respect to e.g. thickness and/or material. Depending on the material selection, it may only be necessary on the side of the absorber layer 22 to provide the second intermediate layer 24a,b. A further possibility includes having alternatingly the first intermediate layer on the absorber layer and the second intermediate layer on the spacer layer and vice-versa, as is schematically illustrated in FIG. 1d, thus inverting the sequence of the two additional layers depending on the transition being from absorber to spacer or from spacer to absorber layer. In particular, it is also possible to select different materials for the intermediate layers, depending on whether the intermediate layers are to be situated between absorber layer 22 and spacer layer 21 or between spacer layer 21 and absorber layer 22 leading to different intermediate layers, e.g. 23a and 23b or 24a and 24b, respectively. For each type of intermediate layer, more than two different materials can be chosen, in particular in stacks comprising more than two absorber layers and/or spacer layers. As appropriate, the intermediate layers have differing thicknesses depending on the transition being from absorber to spacer or from spacer to absorber layer. The transition between multilayer system and protective coating is shown in detail in FIG. 1e, i.e., in the present example the transition of uppermost absorber layer 22 and protective layer 4. As already explained, the protective layer may be made of one material or assembled from multiple, i.e., two, three, four, or more layers. Preferred materials for the simple or assembled protective layer 4 are, for example, boron carbide, molybdenum boride, boron nitride, silicon nitride, silicon carbide, beryllium oxide, silicon oxide, titanium, titanium nitride, copper gold alloy, nickel, ruthenium, rhodium, iridium, gold, palladium, platinum, osmium, samarium, gadolinium, aluminum oxide, potassium, hafnium, thorium fluoride, natrium fluoride, lithium fluoride, magnesium fluoride, lanthanium fluoride, amorphous carbon, yttrium, niobium, rhodium oxide, ruthenium oxide, cerium, or silicon hydride. In the present example, a first intermediate layer 23 for increasing reflectivity and a second intermediate layer 24 as a barrier and in certain circumstances also for increasing reflectivity are situated between the uppermost absorber layer 22 and the protective layer 4. In the example shown in FIG. 1e, the first intermediate layer 23 is situated between the uppermost absorber layer 22 and the second intermediate layer 24. As needed, the second intermediate layer 24 may also be situated between the protective layer 4 and the first intermediate layer 23 or also on both sides of the first intermediate layer 23. Moreover, the multilayer system may also terminate with a spacer layer instead of with an absorber layer. First and second intermediate layers may then, too, be provided in the way described above at the transition to the protective layer to increase the reflectivity. In the dimensioning of the intermediate layers 23, 24 and the protective layer 4, the total thickness of the protective layer 4 is advantageously selected in a range between approximately 1 nm and approximately 10 nm and the total thickness of first and second intermediate layers 23, 24 is selected in a range between approximately 0.2 nm and approximately 10 nm. The materials for the first and second intermediate layers 23, 24 at the transition to the protective layer 4 may be identical to those for first and second intermediate layers 23a,b, 24a,b between the absorber and spacer layers 22, 21 or may also deviate therefrom. First and second intermediate layers may either be provided at the transition to the protective layer or within the multilayer system or also both at the transition to the protective layer and also within the multilayer system. Some examples will be further explained on the basis of a stack with the materials molybdenum as absorber and silicon as spacer, which are often used in the EUV and soft x-ray wavelength range. The following statements may also be transferred similarly to other suitable multilayer systems for the EUV and soft x-ray wavelength range, such as molybdenum/beryllium, molybdenum carbide/silicon, or ruthenium/silicon. They may also be transferred to multilayer systems which are based on alternating layers made of more than two materials. Furthermore, it is to be noted that the at least two intermediate layers may be used in multilayer systems having both constant and also varying thickness ratios of the individual layers within a stack. Firstly, the interface of molybdenum on silicon will be examined in greater detail. The thickness dependency of the reflectivity of some possible materials for the first intermediate layer on silicon, i.e. the reflectivity enhancing layer, is shown in FIG. 2a, the thickness dependency of the reflectivity of some possible materials for the second intermediate layer on silicon, i.e. the barrier layer, is shown in FIG. 2b. The solid line, which corresponds to a real Mo/Si multilayer system, is used as a comparison measure. A mixed layer, which may be approximately described by Mo7Si3 and typically has a thickness of 8 Å, i.e., 0.8 nm, forms by interdiffusion at the interface between the molybdenum and silicon layers in a real Mo/Li multilayer system. This mixed layer results in a reduction of the maximum reflectivity from just 70% to approximately 69%. In contrast, firstly the influence on the reflectivity of adding an intermediate layer made of ruthenium, rhodium, molybdenum carbide, and ruthenium silicide was studied as a function of the layer thickness. As may be seen from FIG. 2a, with increasing thickness, the reflectivity decreases with an intermediate layer made of molybdenum carbide or ruthenium silicide, but not a strongly as with the genuinely forming intermediate layer made of molybdenum silicide. With rhodium, a slight reflectivity increase may be seen at a thickness of up to approximately 6 Å, but the reflectivity sinks even more strongly at higher thicknesses. An astounding effect may be seen with ruthenium: up to a thickness of 8 Å, the reflectivity increases to above 70%, to then remain constant up to at least 10 Å. All of the materials shown here are fundamentally suitable as a material for the first intermediate layer, because they result in a real reflectivity gain in relation to the pure molybdenum-silicon multilayer system. Based on current observations, ruthenium is especially preferred as the material for the first intermediate layer. Correspondingly, materials which are suitable for the second intermediate layer are shown in FIG. 2b. These are boron carbide, amorphous carbon, and silicon nitride, which are all known for being relatively chemically inert to silicon and also acting as a diffusion barrier. They only differ insignificantly at all thicknesses in their effect on the reflectivity and all result in a still acceptable reflectivity reduction in relation to the normal molybdenum-silicon multilayer system. It is to be noted that silicon carbide is also suitable as a material for the second intermediate layer at the interface molybdenum-on-silicon. It is comparable in its effect on the reflectivity to the materials boron carbide, amorphous carbon, and silicon nitride shown in FIG. 2b. For the interface silicon-on-molybdenum, it has been found that different materials suggest themselves for the reflectivity increase than for the interface molybdenum-on-silicon. In particular yttrium, niobium, niobium silicide, and yttrium silicide were studied in regard to their influence on the maximum reflectivity at the interface silicon on molybdenum. The results are shown in FIG. 3a. All four materials first display an increase of the reflectivity up to maximum of 70% or more and then a drop of the reflectivity. The maximum is already at 4 Å for yttrium silicide, and approximately 6 Å for niobium and niobium silicide, and only shortly before 8 Å for yttrium. The maximum reflectivity is also above 70% at 10 Å. Therefore, based on present observations, yttrium is especially preferred as the material for the first intermediate layer. Boron carbide, amorphous carbon, and silicon nitride were again studied as materials for the second intermediate layer. In contrast to the interface of molybdenum on silicon, intermediate layers made of amorphous carbon and silicon nitride already have a very negative influence on the reflectivity at very low thicknesses at the interface of silicon on molybdenum (see FIG. 3b), while boron carbide results in a slight increase of the reflectivity in relation to the molybdenum/silicon multilayer system having a genuine molybdenum silicide layer for all studied thicknesses. Boron carbide is thus presently preferred as the material for the second intermediate layer at least at the interface silicon-on-molybdenum. Upon more precise observation of the properties of the materials which result in an increase of the maximum relative reflectivity of a multilayer system at an operating wavelength in the EUV and/or soft x-ray wavelength range in relation to a multilayer system without intermediate layers, e.g. a molybdenum/silicon multilayer system, one establishes two variants in particular. This is true in particular for the intermediate layer materials which result in a rise of the reflectivity not only in relation to a real molybdenum/silicon multilayer system having a mixed layer, but rather also in relation to an ideal molybdenum/silicon multilayer system (corresponds to the reflectivity at d=0 Å in FIGS. 2a,b, 3a,b). In a first variant, at least the material of the first additional layer 23a,b, i.e. the reflectivity enhancing layer, has an index of refraction whose value of the real part of the index of refraction at the operating wavelength is either greater than the corresponding value of the alternating material having the higher real part of the index of refraction or is lower than the corresponding value of the alternating material having the lower real part of the index of refraction. The optical contrast within the multilayer system is thus increased and thus also the reflectivity. For example, in the case observed here of a molybdenum/silicon multilayer system, ruthenium is suitable as the material of the first additional layer 23a above a silicon layer and below a molybdenum layer, which has a significantly lower real part of the index of refraction at the operating wavelength of 13.5 nm here than molybdenum (see also Table 1). For the selection of the thickness of the first additional layer it is to be ensured that it is not selected as so high that the effect of the reflectivity gain is compensated for because of the higher optical contrast due to the additional absorption because of the first additional layer. This is important in particular with materials having a high imaginary part of the index of refraction at the operating wavelength such as ruthenium (see also Table 1). In a second variant, at least the material of the first additional layer has an index of refraction whose value of the real part of the index of refraction at the operating wavelength is between the corresponding values of the alternating materials. Such a material does tend to reduce the optical contrast of the multilayer system. However, it results in a shift of the standing wave of the electrical field which forms upon irradiation of the multilayer system by refraction at the individual layer boundaries and interference. The standing wave field has a total absorption which is primarily influenced by the overall distribution of the intensities in the various layers in connection with the individual absorptions of the layers because of their particular materials, which are determined by the imaginary part of their indices of refraction. By incorporating the additional layer, the distributions of the intensities shift, so that another total absorption of the standing wave field results. As a special case, the position of the extremes and the nodes are shifted by additional layers made of material whose value of the real part of the index of refraction at the operating wavelength is between the corresponding values of the alternating materials in such a way that the maxima are shifted out of areas made of material having a relatively high imaginary part of the index of refraction, i.e., higher absorption, into areas made of material having a relatively low imaginary part of the index of refraction, i.e., lower absorption. The absorption thus reduced results in an increased reflectivity. It is to be noted that the suitable materials for the additional layers in the suitable thickness range are to be ascertained again for every multilayer system, because too large or too small a shift of the standing wave field may also result in an increase of the total absorption and reduction of the reflectivity. In the example described here of a molybdenum/silicon multilayer system, for example, yttrium and niobium are particularly suitable as the material for the first additional layer above a molybdenum layer and below a silicon layer. Materials that are suitable as second intermediate layer, i.e. as barrier layer, often show a low enthalpy of formation with respect to the adjacent material, in the present case the material of the first intermediate layer and the spacer and/or the absorber layer. They often show a low diffusion rate with respect to the adjacent material. Besides, they often show a tendency to grow layers as closed atomic layers in opposite to an insular growth pattern. Preferably, the material of the second intermediate layer has appropriate optical constants at the operating wavelength, as explained before in relation with the material for the first intermediate layer. It is to be noted that the materials cited in regard to the present example for the first or second intermediate layers are also suitable for corresponding intermediate layers at the transition to a protective layer. The thicknesses of the intermediate layers are preferably less than those of the layers made of the alternating materials which are used as spacer and absorber layers and which define the basic characteristics of the reflective optical element, in particular the operating wavelength range. The thickness of the additional layers is especially preferably less than one fourth of the operating wavelength, in particular less than one eighth of the operating wavelength. For example, for an operating wavelength of 13.5 nm, a molybdenum-silicon multilayer system having yttrium as the first intermediate layer 23a at the silicon-on-molybdenum interface and boron carbide as the second intermediate layer 24a toward the silicon layer 21 as well as ruthenium as the first intermediate layer 23b on the molybdenum-on-silicon interface and boron carbide again as the second intermediate layer 24b toward the silicon layer was produced. All layers were applied by electron beam vapor deposition. The individual layer thicknesses were approximately 2.8 nm for molybdenum, 0.6 nm for yttrium, 0.2 nm for both boron carbide layers, 4.2 nm for silicon, and 0.8 nm for ruthenium. This arrangement included fifty stacks 20. An actual achievable percent maximum reflectivity of somewhat above 71% resulted at the operating wavelength of 13.5 nm. This inventive arrangement corresponds to an increase of more than 2% compared to the 69% which may actually be achieved by a comparable molybdenum-silicon multilayer system without the intermediate layers. For a further example, the reflective optical element just described was produced in that the boron carbide intermediate layers were applied not by electron beam vapor deposition, but rather by magnetron sputtering. In this case as well, a maximum percent reflectivity of somewhat over 71% resulted at an operating wavelength of 13.5 nm. In addition, a further reflective optical element was produced, in which all individual layers were again applied by electron beam vapor deposition. Yttrium was replaced here by niobium as the material for the first intermediate layer at the interface silicon on molybdenum. A maximum percent reflectivity of approximately 71% was achieved at 13.5 nm by this reflective optical element. Reflective optical elements in accordance with the present invention have the further advantage, in addition to their high actually achievable reflectivity, that the structure of their multilayer system also remains stable over longer usage times due to the second intermediate layers in particular. This is because the second intermediate layers prevent interdiffusion with the layers adjoining them also under thermal strain by continuous irradiation with EUV or soft x-ray radiation. The maximum reflectivity at the operating wavelength is thus maintained even in continuous operation. This makes reflective optical elements according to the present invention particularly suitable for use in EUV lithography devices, in which they may be used at diverse locations and in various capacities, as mirror elements or mask elements, for example. An EUV lithography device 100 is schematically illustrated in FIG. 4 and includes the beam shaping system 110, the illumination system 120, the photomask 130, and the projection system 140. For example, a plasma source or also a synchrotron may be used as the radiation source 111. The exiting radiation in the wavelength range of approximately 5 nm to 20 nm is first bundled in the collimator 112. In addition, with the aid of a monochromator 113, the desired operating wavelength is filtered out by varying the angle of incidence. The collimator 112 and the monochromator 113 are typically implemented as reflective optical elements in the cited wavelength range. The use of reflective elements in accordance with the present invention, for example, as the collimator 112 or as the monochromator 113, is advisable particularly in the beam shaping system 110. This is because the thermal strain is especially high here and it is especially important to provide a maximum of EUV radiation by high reflectivity of the following parts. The operating beam, which is prepared in regard to wavelength and spatial distribution in the beam shaping system 110, is then introduced into the illumination system 120. In the example shown in FIG. 4, the illumination system 120 has two mirrors 121, 122, which both have multilayer systems having first and second intermediate layers as previously explained. It is to be noted that the illumination system 120 may also have as few as one mirror or as many as three, four, five, or more mirrors, which may all or partially have a multilayer system having first and second intermediate layers as previously explained. The mirrors 121, 122 conduct the beam to the photomask 130, which has the structure which is to be imaged on the wafer 150. The photomask 130 is also a reflective optical element for the EUV and soft x-ray wavelength range having a multilayer system having first and second intermediate layers. With the aid of the projection system 140, the beam reflected by the photomask 130 is projected on the wafer 150 and the structure of the photomask 130 is thus imaged thereon. The projection system 140 has two mirrors 141, 142 having a multilayer system having first and second intermediate layers in the illustrated example. It is to be noted that the projection system 140 may also have as few as one mirror or as many as three, four, five, or more mirrors, one or more mirrors of which may have a multilayer system having first and second intermediate layers. The above description of exemplary embodiments has been given by way of example. From the disclosure given, those skilled in the art will not only understand the present invention and its attendant advantages, but will also find apparent various changes and modifications to the structures and methods disclosed. The applicant seeks, therefore, to cover all such changes and modifications as fall within the spirit and scope of the invention, as defined by the appended claims, and equivalents thereof. TABLE 1Index of refraction at a wavelength of 13.5 nmNameReal partImaginary partMo0.9237935250.006435425Mo2C0.9177671450.007945986Ru0.8863600340.017064894Rh0.8750488310.031177852Ru2Si0.8995748610.016169887Si0.9990023050.001826494Y0.9737299590.002281516Nb0.9337496910.005195933Nb4Si0.9381468890.005302884Y5Si30.9776117210.002474689B4C0.9637714850.005145842C0.9615734700.006905315Si3Ni40.9731362090.009317771Mo7Si0.9266768920.006498690
	abstract	A power module includes a reactor vessel containing a coolant and a reactor core located near a bottom end of the reactor vessel. A riser section is located above the reactor core, wherein the coolant circulates past the reactor core and up through the riser section. In one embodiment, a coolant deflector shield includes flow-optimized surfaces, wherein the flow-optimized surfaces direct the coolant towards the bottom end of the reactor vessel. In another embodiment, the reactor housing includes an inward facing portion that varies a flow pressure of the coolant and promotes a circulation of the coolant past a baffle assembly and towards the bottom end of the reactor vessel.
047160110	description	DETAILED DESCRIPTION OF THE INVENTION In the following description, like reference characters designate like or corresponding parts throughout the several views of the drawings. Also in the following description, it is to be understood that such terms as "forward", "rearward", "left", "right", "upwardly", "downwardly", and the like are words of convenience and are not to be construed as limiting terms. In General Referring now to the drawings, and particularly to FIGS. 1 to 3, there is shown a nuclear fuel assembly, generally designated 10 for a boiling water nuclear power reactor (BWR), in which the improvement of the present invention is incorporated. The fuel assembly 10 includes an elongated outer tubular flow channel 12 that extends along substantially the entire length of the fuel assembly 10 and interconnects an upper support fixture or top nozzle 14 with a lower base or bottom nozzle 16. The bottom nozzle 16 which serves as an inlet for coolant flow into the outer channel 12 of the fuel assembly 10 includes a plurality of legs 18 for guiding the bottom nozzle 16 and the fuel assembly 10 into a reactor core support plate (not shown) or into fuel storage racks, for example in a spent fuel pool. The outer flow channel 12 generally of rectangular cross-section is made up of four interconnected vertical walls 20 each being displaced about ninety degrees one from the next. Formed in a spaced apart relationship in, and extending in a vertical row at a central location along, the inner surface of each wall 20 of the outer flow channel 12, is a plurality of structural ribs 22. The outer flow channel 12, and thus the ribs 22 formed therein, are preferably formed from a metal material, such as an alloy of zirconium, commonly referred to as Zircaloy. Above the upper ends of the structural ribs 22, a plurality of upwardly-extending attachment studs 24 fixed on the walls 20 of the outer flow channel 12 are used to interconnect the top nozzle 14 to the channel 12. For improving neutron moderation and economy, a hollow water cross, as seen in FIGS. 1 and 2 and generally designated 26, extends axially through the outer channel 12 so as to provide an open inner channel 28 for subcooled moderator flow through the fuel assembly 10 and to divide the fuel assembly into four, separate, elongated compartments 30. The water cross 26 has a plurality of four radial panels 32 composed by a plurality of four, elongated, generally L-shaped, metal angles or sheet members 34 that extend generally along the entire length of the channel 12. The sheet members 34 of each panel 32 are interconnected and spaced apart by a series of elements in the form of dimples (not shown) formed therein and extending therebetween. The dimples are provided in opposing pairs that contact each other along the lengths of the sheet members to maintain the facing portions of the member in a proper spaced-apart relationship. The pairs of contacting dimples are connected together such as by welding to ensure that the spacing between the sheet members 34 forming the panels 32 of the central water cross 26 is accurately maintainedd. The hollow water cross 26 is mounted to the angularly-displaced walls 20 of the outer channel 12. Preferably, the outer, elongated lateral ends of the panels 32 of the water cross 26 are connected such as by welding to the structural ribs 22 along the lengths thereof in order to securely retain the water cross 26 in its desired central position within the fuel assembly 10. Further, the inner ends of the panels together with the outer ends thereof define the inner central cruciform channel 28 which extends the axial length of the hollow water cross 26. Also, the water cross 26 has a lower flow inlet end 36 and an opposite upper flow outlet end 38 which each communicate with the inner channel 28 for providing subcoolant flow therethrough. Disposed within the channel 12 is a bundle of fuel rods 40 which, in the illustrated embodiment, number sixty-four and form an 8.times.8 array. The fuel rod bundle is, in turn, separated into four mini-bundles thereof by the water cross 26. The fuel rods 40 of each mini-bundle, such being sixteen in number in a 4.times.4 array, extend in laterally spaced apart relationship between an upper tie plate 42 and a lower tie plate 44. The fuel rods in each mini-bundle are connected to the upper and lower tie plates 42,44 and together therewith comprise a separate fuel rod subassembly 46 within each of the compartments 30 of the channel 12. A plurality of grids 48 axially spaced along the fuel rods 40 of each fuel rod subassembly 46 maintain the fuel rods in their laterally spaced relationships. The lower and upper tie plates 42,44 of the respective fuel rod subassemblies 46 have flow openings 50 defined therethrough for allowing the flow of the coolant/moderator fluid into and from the separate fuel rod subassemblies. Also, coolant flow paths provide flow communication between the fuel rod subassemblies 46 in the respective separate compartments 30 of the fuel assembly 10 through a plurality of openings 52 formed between each of the structural ribs 22 along the lengths thereof. Coolant flow through the openings 52 serves to equalize the hydraulic pressure between the four separate compartments 30, thereby minimizing the possibility of thermal hydrodynamic instability between the separate fuel rod subassemblies 46. The above-described basic components of the BWR fuel assembly 10 are known in the prior art, being disclosed particularly in the Doshi application cross-referenced above, and have been discussed in sufficient detail herein to enable one skilled in the art to understand the improved feature of the present invention presented hereinafter. For a more detailed description of the construction of the BWR fuel assembly, attention is directed to both of the above cross-referenced Barry et al and Doshsi patent applications. Coolant Flow Direction Control Device Referring now to FIG. 1, and more specifically to FIGS. 3 to 5, there is seen the feature incorporated in the BWR fuel assembly 10 which constitutes the present invention, namely a coolant flow direction control device, generally indicated by the numeral 54. The flow direction control device 54 is mounted in the bottom nozzle 16 of the fuel assembly 10 on an annular ledge or surface 56 formed thereon at an inner end of an inlet 58 of the bottom nozzle so as to surround the inlet. In such location, the flow direction control device 54 is operable basically to open the inlet 58 to flow of coolant fluid in an inflow direction into the flow channel 12 through the bottom nozzle inlet 58 but close the inlet to flow of coolant fluid from the channel 12 through the bottom nozzle inlet upon reversal of coolant liquid flow from the inflow direction. More particularly, the coolant flow direction control device 54 is preferably in the form of a one-way or unidirectional flow check valve positioned across the inlet 58 of the fuel assembly bottom nozzle 16. The coolant flow check valve 54 is operable to sense the direction of coolant flow through the inlet 58 and automatically, by action of the fluid on the valve, open when the flow direction sensed is into the bottom nozzle 16 (in the direction of arrow A in FIG. 4) and close when the flow direction sensed is out of the bottom nozzle (in the direction of arrow B in FIG. 4). In an exemplary embodiment, the flow check valve 54 is composed of four parts 54a,54b,54c,54d. Each part of the check valve 54 is quarter pie-shaped and has an outer portion 60 mounted to the bottom nozzle 16 on its annular surface 56 and adjacent to its inlet 58 and an inner portion 62 being connected to the respective outer portion 60 by a middle hinge portion 64 for pivotal movement relative to one another. The inner portions 62 of the valve 54 together pivot about the respective outer portions 60 between lowered positions, as seen in solid line form in FIGS. 4 and 5, and raised positions, as seen in broken line form in FIG. 4. The inner valve portions 62 are configured to extend in close fitting relationship adjacent to one another and coplanarly across the inlet 58, as seen in FIGS. 4 and 5, so as to close it when disposed in their respective lowered positions. Then, when disposed in their respective raised positions, as seen in FIG. 4, the inner portions 62 extend in generally parallel relationship to the direction of flow A an are disposed remote from one another so as to open the inlet 58. The inner valve portions 62 are arranged in first and second pairs which, as depicted in FIG. 5, are angularly displaced about ninety degrees from one another. In such arrangement, the inner valve portions 62 of each pair are placed in opposing relation to one another such that one is a mirror image of the other. Additionally, the inner valve portions 62 located directly opposite to one another in the respective pairs thereof extend generally parallel to one another when in their raised positions. The outer valve portions 60, in being mounted to the annular surface 56 of the bottom nozzle 16 which concentrically surrounds its inlet 58, are configured for attachment on respective circumferentially spaced sectors 66 of the surface 56, as seen in FIG. 5. The inner valve portions 62, when in their respective lowered positions as seen in FIG. 5, are configured for seating on respective circumferentially spaced segments 68 of the annular surface 56 which alternate with the spaced sectors 66 of the surface 56 and constitute the remainder thereof. Whereas in their raised positions the inner valve portions 62 extend toward the bottom nozzle 16 in the direction of coolant flow (arrow A) into the bottom nozzle, in their lowered positions their seating on the annular surface 56 stops them from pivoting past the lowered position so as to prevent them from extending away from the bottom nozzle 16 in a direction (arrow B) opposite to that of their raised positions which would allow reverse flow of coolant therefrom. Thus, the primary characteristic of the flow direction control device 54, whatever specific form it might take, should be that it provides unrestricted flow through the bottom nozzle inlet 58 into the fuel assembly during normal operation. Then, upon occurrence of LOCA flow reversal (initiation of core coolant inventory depletion), the flow reversal should cause the device to shut automatically, preventing any further depletion via the bottom nozzle. A principle requirement of this device should be reliability in operation and freedom from corrosion. The material of the device 54 might be a titanium alloy. The advantage of having multiple closure members or portions making up the device 54 is that in case one portion gets stuck and fails to close upon flow reversal, the others would then introduce a partial closure, which would still be beneficial. However, it is possible to use only one closure member. It is thought that the invention and many of its attendant advantages will be understood from the foregoing description and it will be apparent that various changes may be made in the form, construction and arrangement thereof without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the form hereinbefore described being merely a preferred or exemplary embodiment thereof.
047599111	claims	1. A gas cooled nuclear fuel element, comprising a plurality of rigid porous cylinders suitably sized for coaxial positioning of each of the smaller of said cylinders within the next largest cylinder, wherein said cylinders are provided with varying quantities of fissionable nuclear fuel to maximize the total power production within the element. 2. The fuel element of claim 1, wherein said fuel element is designed for radial gas flowthrough and axial gas outflow. 3. The fuel element of claim 1, wherein said fuel element is provided with the nuclear fuel uranium carbide. 4. The fuel element of claim 1, wherein said fuel element is provided with the nuclear fuel plutonium carbide. 5. The fuel element of claim 1, wherein said fuel element is provided with the nuclear fuel americium carbide. 6. The fuel element of claim 1, wherein said fuel element is provided with the nuclear fuel uranium dicarbide. 7. The fuel element of claim 1, wherein said porous cylinders have pores in the range of 0.5 to 5.0 millimeters. 8. The fuel element of claim 1, wherein said porous cylinders are formed from reticulated vitreous carbon. 9. The fuel element of claim 1, further comprising a protective layer of carbon on said cylinders. 10. The fuel element of claim 1, further comprising a protective layer of zirconium carbide on said cylinders. 11. A process for preparing a gas cooled nuclear fuel element, comprising: a. selecting a retriculated vitreous carbon skeleton of appropriate pore and ligament size; b. depositing a fissile material on said skeleton; and c. subjecting said coated skeleton to high temperature whereby said fissile material is changed to its carbide form. 12. The process of claim 11, further comprising depositing a protective layer of carbon on said coated skeleton. 13. The process of claim 12, further comprising depositing a protective layer of zirconium carbide over said carbon layer. 14. The process of claim 11, wherein said depositing of fissile material is accomplished by vapor deposition coating. 15. The process of claim 11, wherein the pore size of said skeleton ranges from 0.5 to 5.0 millimeters.
053496140	description	DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 and 4, the steam line plug installation tool 10 in accordance with the preferred embodiment of the invention can be used to insert a plug 12 with inflatable seal in the steam outlet nozzle 14 of the pressure vessel 16 of a BWR. The tool 10 is hung on the reactor vessel flange 18 using handling bracket 20. Handling bracket 20 is maintained in a horizontal position by holding pawl 21. Upon release of holding pawl 21, handling bracket 20 can be rotated downward by 90.degree. and out of the way of the steam separator assembly during the latter's removal. The plug installation tool is hung by seating hanger bracket 19 on top of vessel flange 18. In this position, the vessel supports the tool with actuating channel 24 of the latter bearing against the vessel wall 26. A guide plate 23 is bolted to a hanger plate 22 of hanger bracket 19. The tool is hooked onto reactor vessel flange 18 via hook 23a of guide plate 23. An actuating screw assembly 25 (see FIG. 5) is mounted inside actuating channel 24. This assembly comprises an actuating screw 28 (with hexagonal head which is supported at respective ends by upper and lower support blocks 88 and 88' welded to actuating channel 24. Actuating screw rotates freely without vertically displacing relative to support blocks 88, 88'. Vertical displacement of actuating screw 28 is blocked by collars 90, 90' secured thereto. Actuating screw 28 is threadably coupled to bronze acme nut 92, which is in turn secured to carriage block 30 having axle shafts 32 at respective ends thereof. Carriage block 30 rides in a pair of parallel vertical slots (not shown) formed in actuating channel 24 in response to rotation of actuating screw 28. A fixed lower axle mount 34, having axle shafts 36 at respective ends thereof, is also mounted in the bottom end of actuating channel 24. The ends of a pair of inside scissors bars 38 are pivotably coupled to respective axle shafts 32. Similarly, the ends of a pair of outside scissors bars 40 are pivotably coupled to respective axle shafts 36. Each inside scissors bar 38 is pivotably coupled to the corresponding outside scissors bar 40 by way of a pivot pin 42. The other ends of inside scissors bars 38 are pivotably coupled to pivot pins 44 which are mounted in and extend from a plug support tube 46. Plug support tube 46 is substantially parallel to actuating channel 24. The other ends of outside scissors bars 40 are pivotably coupled to pivot pins 48 which are mounted in and extend from a scissors slide collar 50 which is slidable along plug support tube 46. This arrangement of pivot pins, axle shafts and scissors bars constitutes the scissors jack assembly 45 for linearly displacing plug support tube 46 toward and away from actuating channel 24. In response to rotation of actuating screw 28 when the tool is in the state shown in FIG. 1, the carriage block 30 and the ends of inside scissors bars 38 connected thereto are vertically displaced. Scissors slide collar 50 is simultaneously vertically displaced. As a result, the scissors jack assembly 45 collapses into the state shown in FIG. 4. The plug 12 with inflatable seal is attached to a plug mounting ring 52, which is shown in detail in FIG. 6. Plug mounting ring 52 is connected to right and left strongback bars 56 and 56' of strongback assembly 54. Strongback bars 56 and 56' are rigidly connected by upper slide bar 58, lower slide bar 60 and cross bar 62. Strongback assembly 54 is adjustably supported by upper and lower slide support plates 64 and 66 respectively welded to the plug support tube 46. As best seen in FIG. 3, the elevation of strongback assembly 54--and consequently, the elevation of plug 12--relative to plug support tube 46 can be finely adjusted by turning adjustment screw 68. The threaded portion of adjustment screw 68 is screwed into a threaded bore in upper slide support plate 64, while the end of adjustment screw 68 bears against upper slide bar 58. Strongback assembly 54 is lowered relative to plug support tube 46 when adjustment screw 68 is rotated clockwise, thereby overcoming the resistance of a heavy-duty compression spring 70. When adjustment screw 68 is rotated in the opposite direction, compression spring 70 urges strongback assembly 54 upward relative to plug support tube 46. The compression spring 70 is supported by collar 102 securely mounted on slide shaft 100, on which upper and lower slide bars 58 and 60 slide. Slide shaft 100 is in turn supported by threads in upper slide support plate 64 and securely pinned to lower slide support plate 66. Slide shaft 100 slides in bushings (not shown) respectively seated in upper and lower slide bars 58 and 60. The fine adjustment of the elevation of strongback assembly 54 relative to plug support 46 is added to the coarse adjustment of the elevation of plug support tube 46 relative to the reactor flange. The elevation of plug support tube 46 is adjusted by sliding actuating channel 24 relative to hanger bracket 19 and then tightening six mounting screws 73 when actuating channel 24 is at the desired position (see FIG. 2). The midportions of mounting screws 73 slide in slotted mounting holes 74 formed in hanger bracket 19 and the ends of screws 73 are screwed into threaded bores (not shown) in actuating channel 24. Coarse adjustment is accomplished prior to installation by positioning the hanger bracket 19 with respect to the plug centerline using the six slotted mounting holes 74. The inflatable seal (not shown) of plug 12 is remotely inflated after plug installation by manipulating a control console 76 and setting a four-way valve 78 to expand mechanical grips (not shown). An air supply line 80 and a vent line 82 connect control console 76 to the inflatable seal. Three motor actuating lines 84 connect four-way valve 78 to an actuating air impact motor 103 (see FIGS. 7A and 7B), which is coupled to the inflatable seal for expanding the mechanical grips of the seal against the walls of nozzle 14. Lines 80, 82 and 84 pass through the channel of the plug support tube 46. The installation and operation of the plug assembly of the invention are as follows: The plug assembly is staged upright in a staging stand for transfer to the jet pump grapple on the refueling bridge- As an alternative, the plug can be located in a fixture mounted off the wall of the reactor cavity, thus eliminating the need to transfer to the jet pump grapple using the overhead crane. The control console 76 and four-way valve 78 are located on the reactor cavity handrails 86 at the azimuth of the steam line for plug installation. The air supply and actuating lines are unrolled and staged for hookup to the installation tool. The jet pump grapple (not shown) on the monorail hoist is hooked up to the installation tool handling bracket 20. The handling bracket is temporarily maintained in the horizontal position using a pawl 21 as shown in FIG. 2. This feature facilitates the hookup and removal of the grapple. With the steam line plug assembly hanging from the monorail hoist, the assembly is lowered until the air lines can be attached to the quick disconnects. A safety tag line is also hooked up to an eye bolt on the hanger bracket. The plug assembly is then lowered into the reactor cavity and positioned on the reactor vessel flange 18 at the azimuth of the steam line nozzle. Guide plate 23, which is bolted to hanger plate 22, hooks over the reactor vessel flange 18 and positions the plug 12 at the correct azimuth using the reactor head studs 72 as a reference. The jet pump grapple is released from the handling bracket 20. An actuating service pole (not shown) with a 1-inch socket adapter is then lowered and mated to the hexagonal head 29 of actuating screw 28 (see FIG. The service pole is turned clockwise, causing the actuating screw carriage 30 to collapse the scissors jack assembly 45, thereby inserting plug 12 into nozzle 14. An underwater TV camera (not shown) can be used to monitor the insertion and verify position. If the elevation needs to be further adjusted, the fine elevation adjustment screw 68 (see FIG. 3) can be turned to raise or lower the plug .+-.3/8 inch as necessary. To accomplish this, the service pole is removed from actuating screw 28 and mated to the hexagonal head of fine elevation adjustment screw 68. Using the underwater camera to monitor the plug, adjusting screw 68 is turned as necessary to lower or raise the plug. Pre-loaded compression spring 70 will raise the plug if necessary to increase its elevation. If the plug elevation is too high, compression spring 70 will compress as necessary. Once the plug is inserted, the service pole is used to tap the arm of pawl 21 to release the handling bracket 20. Handling bracket 20 will fold down over the back of the scissors slide collar 50 and plug support tube 46. The handling bracket provides a tapered guide surface 20a to prevent snagging during installation and removal of the steam separator from the reactor vessel. Thereafter, the air lines are hooked up to the quick disconnects on the four-way valve 78 and control console 76. A 90-psig air supply is hooked up to four-way valve 78 and a 150-psig air supply is hooked up to a 1/4-inch NPT connection on control console 76. Then the operating lever on the four-way valve is turned to the (I) position and hold for 40 sec to engage the holding grips (not shown) of the steam line plug 12. Binoculars or the underwater camera can be used to verify that the plug has engaged the proper amount of travel by observing that a position indicator rod (not shown) is positioned in the full travel range. After the plug is in the proper position, the pneumatic seal is inflated to actuate the plug secondary seal. The absence of air leaks should be verified by visually observing whether any bubbles are rising from the plug. This completes the plug installation operation. In order to remove the air impact motor 103 from the inflatable seal in the event of motor failure, the installation tool incorporates a remotely operable double latch bar arrangement as shown in FIGS. 7A and 7B. The latch consists of latch handle 94, eccentric bushing 96, latch hook 98 and latch bar 99. Air impact motor 103 has a handle bar 106 which is secured into a pair of notches 110 on the back side of strongback bars 56 and 56'. Hook latches 94 lock over handle bar 106. Then the eccentric bushings 96 are turned to pull on the handle bar by way of the hook latches to firmly securely the air impact motor to the strongback assembly. At the same time, an O-ring compression flange 104 on the air impact motor is compressed onto a mating flange on the inflatable seal assembly, thereby maintaining a watertight seal around the air impact motor. Latch bar 99 prevents latch hook 98 from disengaging due to vibration when operating the air impact motor. The latch handles allow standard actuating poles to be used to pull up the latches and remove a failed air impact motor while the plug is installed underwater. A separate air impact recovery tool (not shown) is used to disengage the steam plug holding grips when the failed motor is pulled out of the way. This feature is advantageous in that the water level in the reactor need not be drained down to the steam nozzle level to main physical access to the plug in the event of air impact motor failure. Thus, there would be minimal impact on the schedule for reactor reassembly which follows removal of the steamline plugs. When it is time to remove the plug assembly in accordance with the invention, this can be accomplished as follows: The secondary seal is deflated by turning the inflatable seal valve of control console 76 to the vent position. Also the LLRT/Vent Line valve on control console 76 is turned to the vent position. The operating lever on the four-way valve is moved to the (R) position and held to release the plug holding grips. Using binoculars or the underwater camera, the operator then verifies that the plug has released the amount of travel by observing that the position indicator rod is in the released travel range. Thereafter, the operator verifies that the steam line has completely backfilled with water by observing that air bubbles have ceased. Using a rope or service pole with a J-hook, handling bracket 20 is snagged and pulled up to its horizontal position, whereat it engages the holding pawl 21 and is locked in place. A service pole with a 1-inch socket adaptor is lowered onto the hexagonal head 29 of actuating screw 28 and turned counterclockwise to expand the scissors jack assembly 45, thereby retracting plug 12 from steam line nozzle 14. After plug 12 has been fully retracted, the service pole is removed and the jet pump grapple is lowered and engaged with handling bracket 20. The plug installation tool 10 is slowly raised off of the vessel flange 18 and backed away from the studs 72. Once clear of the studs, the assembly 10 is raised to the surface and transferred to the staging fixture. The operating air lines are then disconnected from the plug assembly, control console and four-way valve. The plug assembly is then decontaminated and stored in a storage container. The foregoing preferred embodiment has been described for the purpose of illustration only. Various modifications of the steam line plug installation tool in accordance with the invention will be readily apparent to a skilled engineer. The appended claims are intended to encompass all such variations and modifications.
	abstract	A duct-type spacer grid for nuclear fuel assemblies is disclosed. In this spacer grid, a plurality of duct-shaped grid elements, individually having an octagonal cell, are closely arranged in parallel and are welded together, thus forming a matrix structure. The grid elements do not pass across the center of the subchannel of the assembly, thus effectively reducing pressure loss. Each of the grid elements is formed as an independent cell, and so they effectively resist against a lateral impact. A plurality of integral type swirl flow vanes, having different heights or same height, axially extend from the top of the grid to be positioned within each subchannel. The swirl flow vanes are bent outwardly, and so they do not contact the fuel rods during an insertion of the fuel rods into the cells. In the spacer grid, the fuel rods are supported within the cells by line contact springs without using any dimple. The spacer grid thus uniformly distributes its spring force on the fuel rods and almost completely prevents damage of the fuel rods due to fretting wear.
	claims	1. Laminated lead-free radiation shielding device comprising at least two individual composite layers,each individual composite layer comprising a secondary radiation layer with a material comprising chemical elements with a low atomic number and a barrier layer with a material comprising chemical elements with a high atomic number,wherein the individual composite layers are arranged in the radiation shielding device in such a way that a barrier layer is arranged on both surfaces of the radiation shielding device and the respective secondary radiation layer is arranged at a distance from the surfaces. 2. Radiation shielding device according to claim 1, wherein one individual composite layer has a protection value of 0.25 mm Pb nominal value or less. 3. Radiation shielding device according to claim 2, wherein one individual composite layer has a protection value of 0.125 mm Pb nominal value and the individual composite layers are identical. 4. Radiation shielding device according to claim 2, wherein the individual composite layers have an identical protection value. 5. Radiation shielding device according to claim 1, wherein one individual composite layer comprises a reinforcing layer. 6. Radiation shielding device according to claim 5, wherein the reinforcing layer is arranged between the barrier layer and the secondary radiation layer. 7. Radiation shielding device according to claim 5, wherein the reinforcing layer is provided on the outside of the individual composite layer. 8. Radiation shielding device according to claim 7, wherein the reinforcing layer is a covering layer for radiation protection clothing. 9. Radiation shielding device according to claim 8, wherein the reinforcing layer comprises an aramide fabric or a glass-fiber fabric. 10. Radiation shielding device according to claim 5, wherein the reinforcing layer comprises a thin, tear-resistance fabric. 11. Radiation shielding device according to claim 5, wherein the reinforcing layer comprises carbon fibers. 12. Radiation shielding device according to claim 5, furthermore comprising a sliding layer between the individual layers of the radiation shielding device. 13. Radiation shielding device according to claim 1, wherein the material comprising chemical elements with a low atomic number of the secondary radiation layer comprises elements with an atomic number Z of 39 to 60. 14. Radiation shielding device according to claim 13, wherein the material comprising chemical elements with a low atomic number comprises at least one of the following elements: tin, antimony, iodine, caesium, barium, lanthanum, cerium, praseodymium and neodymium. 15. Radiation shielding device according to claim 13, wherein the material comprising chemical elements with a low atomic number additionally comprises at least one of the elements with an atomic number between Z>60 and Z=70. 16. Radiation shielding device according to claim 13, wherein the material comprising chemical elements with a low atomic number is a mixture of tin and at least one of the elements lanthanum, cerium or gadolinium. 17. Radiation shielding device according to claim 13, wherein the material comprising chemical elements with a low atomic number is a mixture of antimony and at least one of the elements lanthanum, cerium or gadolinium. 18. Radiation shielding device according to claim 1, wherein the material comprising chemical elements with a high atomic number of the barrier layer is a material with a high absorption coefficient with respect to the secondary radiation emitting from the secondary radiation layer. 19. Radiation shielding device according to claim 1, wherein the material comprising chemical elements with a high atomic number of the barrier layer comprises elements with an atomic number Z higher than 60 with the exception of lead. 20. Radiation shielding device according to claim 19, wherein the material comprising chemical elements with a high atomic number comprises elements with an atomic number Z higher than 70. 21. Radiation shielding device according to claim 20, wherein the material comprising chemical elements with a high atomic number additionally comprises at least one element with an atomic number between Z>60 and 70. 22. Radiation shielding device according to claim 19, wherein the material comprising chemical elements with a high atomic number comprises tantalum and/or bismuth and/or tungsten. 23. Radiation shielding device according to claim 1, wherein the radiation shielding device with 0.25 mm Pb nominal value comprises two individual composite layers. 24. Radiation shielding device according to claim 1, wherein the radiation shielding device with 0.35 mm Pb nominal value comprises three individual composite layer. 25. Radiation shielding device according to claim 1, wherein the radiation shielding device with 0.50 mm Pb nominal value comprises four individual composite layers wherein each barrier layer is arranged outside facing the next surface of the radiation shielding device. 26. Radiation shielding device according to claim 1, wherein the radiation shielding device with 0.50 mm Pb nominal value comprises five individual composite layers wherein each barrier layer is arranged outside facing the next surface of the radiation shielding device. 27. Radiation shielding device according to claim 1, furthermore comprising an outer covering layer. 28. Radiation shielding device according to claim 27, wherein the outer covering layer comprises textile material and/or PVC. 29. Radiation shielding device according to claim 27, wherein the covering layer is integrally coated with a barrier layer. 30. Radiation protection clothing or radiation protection device comprising a radiation shielding device according to claim 1. 31. Radiation protection clothing or radiation protection device according to claim 30, wherein in case of an asymmetrical structure of the radiation shielding device the surface with more barrier layers in its vicinity is arranged closer to the body to be protected.
	claims	1. A cutting method for cutting up a reinforced concrete mass, the method comprising:providing a drilling tool comprising:a drill tube having a longitudinal direction and presenting a distal end that carries a cutter member;a device for causing the drill tube to vibrate, which device comprises a vibration generator for generating longitudinal vibration in the drill tube;a device for injecting a drilling fluid into the mass at the distal end of the drill tube; anda device for moving the drill tube in its longitudinal direction;cutting the reinforced concrete mass by drilling at least one hole with the help of the drill tool while causing the drill tube to vibrate with the help of the vibration generator and simultaneously injecting the drilling fluid into the reinforced concrete mass at the distal end of the drill tube,wherein drilling parameters are measured while drilling a first hole in the reinforced concrete mass, and wherein a second hole is then drilled in the reinforced concrete mass after configuring the drill tool with the help of the parameters measured during drilling of the first hole. 2. The cutting method according to claim 1, wherein a succession of intersecting drillholes is made in the reinforced concrete mass with the help of the drill tool while causing the drill tube to vibrate, thereby obtaining a continuous line of cut. 3. The cutting method according to claim 2, wherein, in the event of one of the drillholes being deflected, a re-boring step is performed on the deflected drillhole by drilling an additional drillhole in the deflected drillhole, the additional drillhole having a diameter greater than the diameter of the deflected drillhole such that the additional drillhole intersects one of the drillholes adjacent to the deflected drillhole. 4. The cutting method according to claim 1, further comprising the steps of:drilling at least two primary drillholes in the reinforced concrete mass with the help of the drill tool by causing the drill tube to vibrate, the primary drillholes being spaced apart from each other; andcutting away a portion of concrete situated between the two primary drillholes, thereby obtaining a continuous line of cut. 5. The cutting method according to claim 4, wherein, in order to cut away the portion of concrete situated between the two primary drillholes, at least one secondary drillhole is drilled in the reinforced concrete mass with the help of the drill tool by causing the drill tube to vibrate, the secondary drillhole being made between the two previously drilled primary drillholes so as to intersect the two primary drillholes, whereby the succession of the primary drillholes and of the secondary drillhole intersecting the primary drillholes forms a continuous line of cut in the reinforced concrete mass. 6. The cutting method according to claim 5, wherein a diameter of the secondary drillhole is greater than a diameter of the primary drillholes. 7. The cutting method according to claim 5, wherein, in the event of one of the primary drillholes being deflected, after drilling the secondary drillhole, a re-boring step is also performed of re-boring the deflected primary drillhole by drilling an additional drillhole in the primary drillhole, the additional drillhole having a diameter greater than the diameter of the primary drillhole such that the additional drillhole intersects the secondary drillhole. 8. The cutting method according to claim 5, wherein a series of primary drillholes is drilled followed by a series of secondary drillholes, each secondary drillhole being drilled between two primary drillholes so as to intersect both primary drillholes. 9. The cutting method according to claim 8, wherein diameters of the secondary drillholes are greater than diameters of the primary drillholes. 10. The cutting method according to claim 1, wherein at least one of the drillholes is drilled by coring. 11. The cutting method according to claim 1, wherein the drilling fluid is a foam, water, or air. 12. The cutting method according to claim 1, wherein, during drilling, the treated effluent is used as drilling fluid. 13. The cutting method according to claim 1, wherein the drill tool further includes a device for setting the drill tube into rotation, and in that the drill tube is set into rotation while drilling the at least one drillhole. 14. The cutting method according to claim 13, wherein the torque applied to the drill tube while drilling the drillhole is measured, and in that deflection, if any, of the drilling direction is detected by means of the measured torque. 15. A method of dismantling containment buildings of a nuclear power station including at least one reinforced concrete mass, wherein the reinforced concrete mass is cut up by performing the cutting method according to claim 1. 16. An installation for cutting up a reinforced concrete mass by performing the cutting method according to claim 1, the installation including a drill tool comprising:a drill tube having a longitudinal direction and presenting a distal end carrying a cutter member;a device for causing the drill tube to vibrate, which device comprise a vibration generator for generating longitudinal vibration in the drill tube;a device for moving the drill tube along its longitudinal direction; anda device for injecting a drilling fluid into the mass at the distal end of the drill tube;the installation being arranged to cut up the reinforced concrete mass by drilling at least one drillhole with the help of the drill tool by causing the drill tube to vibrate with the help of the vibration generator while simultaneously injecting the drilling fluid into the mass at the distal end of the drill tube. 17. The installation according to claim 16, wherein the drilling fluid is foam, water, or air. 18. The installation according to claim 16, wherein it further includes a collector device for collecting the effluent generated while drilling the drillholes. 19. The installation according to claim 18, wherein the collector device comprises an effluent collector fastened to the reinforced concrete mass so as to surround the drill tube, and a treatment device for treating effluent that is connected to the collector and to the device for injecting the drilling fluid into the mass from the distal end of the drill tube.
048511862	description	DESCRIPTION OF PREFERRED EMBODIMENT FIG. 1 shows a fuel assembly 1 in operating position in the support 2 of a nuclear reactor core according to the prior art. The support 2 or bolster comprises a horizontal upper plate 3, a horizontal lower plate 4 and an assembly of tubular sleeves 5 having a vertical axis, termed pillars. The pillars 5 interconnect the upper part and the lower part of the bolster which defines a free space between its upper plate 3 and lower plate 4. Liquid sodium for cooling the core is injected by primary pumps of the nuclear reactor into this space in the bolster 2. Each of the pillars 5 has an inner bore having a shape enabling it to receive the lower part 1a or foot of an assembly 1. The pillars include openings 6 extending through their lateral wall in confronting relation to corresponding openings 7 provided in the foot of the assemblies. Liquid sodium coolant can in this way enter the foot of the assembly and circulate in the vertical upward direction within this assembly for cooling the latter (arrows 10). The lower part 12 of the foot of the assembly, of cylindrical shape with a circular section, is engaged in a corresponding part 13 of the inner bore of the pillar 5. The assembly 1 is therefore mounted in the bolster 2 to be rotatable about the vertical axis of the pillar 14 which is coincident with the vertical axis of the assembly. The part of the assembly 1 disposed above the foot 1a, and constituting the body 1b of this assembly, has a hexagonal cross-sectional shape, as shown in FIG. 2. In this figure, it can be seen that the adjacent assemblies 20a, 20b, 20c . . . , constituting the network of the core, are in contact by their lateral surfaces, each assembly surrounded by six identical assemblies occupying a prismatic cell having a hexagonal section defined by the adjacent assemblies. When the assemblies 1 are placed in position to constitute the first charge of the core, the assemblies are self-orientable, each about its vertical axis 14, owing to the provision of guide and orientation surfaces 16 machined in the lower part of the body 1b of each of the assemblies. The guide and orientation surfaces 16 of the adjacent assemblies cooperate to provide a suitable relative orientation of the assemblies relative to one another. At the moment of the constitution of the first core with false assemblies, the shape to be given to the guide and orientation surfaces 16 of each of the assemblies is determined in a precise manner. In particular, the orientatin of the assemblies must ensure a perfect alignment between the openings 7 of the foot 1a of each of the assemblies with the opening 6 of the corresponding pillar 5. The body 1b of the assembly 1 is connected in its upper part with a relatively massive head 17 which has a double function. The head 17 first of all ensures the suspension of a group of bars 18 of a material which absorbs the neutrons and provides the neutronic protection of the upper structures of the reactor. The head 17 also includes an inner part 19 terminating in a shoulder which enables the assembly to be seized by the grab of the machine handling the assemblies of the reactor. The head 17 is fixed by a forming over or setting operation or by welding to the body 1b of the assembly. When the nuclear reactor is operating, the head part 17 of the assemblies is subjected to considerable stresses of thermal origin owing to the conditions prevailing in this region of the core. The massive head 17 and its connection to the body 1b of the assembly are therefore difficult construct. In FIG. 3, a part of a nucleaar reactor core according to the invention has been shown with a cross-sectional shape in the region of the body of the assemblies corresponding to that represented in FIG. 2. An assembly 21 of a core according to the invention is shown in its position extracted from the core and in its operating position in the core in FIG. 3. In FIG. 4, the assembly 21 is shown to an enlarged scale and partly in section. The core according to the invention has a general structure similar to the core of the prior art reactor shown in FIG. 1. It comprises a bolster 22 constituted by an upper plate 23 and a lower plate 24 interconnected by tubular struts or pillars 25. The tubular struts 25 receive the feet 21a of the assemblies which are provided with openings 27 which come into alignment with openings 26 provided in the corresponding pillars 25 for the passage of the liquid sodium in the assembly 21. The lower part 30 of the foot 21a of the assembly 21 has a prismatic shape with a hexagonal section whose axis is coincident with the axis 32 of the pillar 25, and the assembly 21 and the bore of the pillar 25 includes a corresponding part 31 of prismatic shape also having the axis 32 for its axis. The orientation of the assembly 21 relative to the bolster 22 is thus ensured by the corresponding male and female prismatic surfaces 30 and 31, at the moment at which the foot 21a of the assembly is inserted in the bolster 22. This orientation, which corresponds to a perfect alignment of the openings 27 and openings 26, is maintained, when the assembly is in the service position in the core, as shown in the right-hand part of FIG. 3, the assembly 21 being prevented from rotating about its axis inside the bore of the pillar 25. The design of the bolster 22 and, in particular the position and the orientation of the pillars 25 relative to one another, is such that the bodies 21b of the assemblies whose feet 21a are prevented from rotating in the pillars 25 of the bolster 22, are disposed in a hexagonal network whose section is shown in FIG. 2. It is now no longer necessary to provide guide and orientation surfaces similar to the surfaces 16 of the prior art assembly 1 in the lower part of the body 21b of the assembly of a core according to the invention. FIG. 4 shows the upper part of the body 21b of the assembly which comprises a simple tubular member 37 having a hexagonal section for supporting the bars 38 of the upper neutronic protection of the assembly instead of a massive member such as the member 17 of an assembly according to the prior art shown in FIG. 1. The member 37 is set or welded inside the case of the body 21b of the assembly. This case of the body 21b is extended above the member 37 and includes in this upper region through openings 39 permitting the engagement of claws of the grab handling the assembly. FIG. 5 shows the case 40 of the body of a control assembly of the nuclear reactor. This case 40 of hexagonal shape is identical to the case of the body 21b of a fuel assembly such as that shown in FIGS. 3 and 4. The foot part of the control assembly (not shown) is identical to the foot part 21a of a fuel assembly such as that shown in FIGS. 3 and 4. The case 40 of the control assembly includes through openings 41 in its upper part for the introduction of the claws of a handling grab when placing the fixed guide part 40 of the assembly in the core. The fixed part 40 is adapted to receive an absorber unit 42 which is vertically movable in the core by means of a mechanism comprising a control rod of great length which may be connected to the head 43 of the absorber unit 42 by means of an electromagnet 44. The assembly shown in FIG. 5 is a control assembly enabling the reactor to be stopped urgently in the event of an incident. Several assemblies identical to the control assembly shown in FIG. 5 are placed in predetermined positions in the core. When the reactor is operating normally, the absorber units 42 of these assemblies are in the upper position represented in FIG. 5 and maintained in this position by the electromagnets 44. In the event of an incident, the supply current of the electromagnets 44 is cut off and the units 42 drop to the lower position of maximum insertion in the core of the reactor. The lower part 45 of the absorber assembly 42 constitutes with the foot part of the case 40 of the assembly (not shown) a dash-pot which absorbs the kinetic energy acquired by the absorber assembly 42 during its fall. When the absorber assemblies 42 are in their position of maximum insertion in the core, the neutronic power of the core is reduced to a very low value. The control assemblies of the prior art comprise, as the fuel assemblies, a massive head member for handling the assembly and placing it in position or retracting it from the core. This massive member connected to the upper part of the case of the assembly results in a reduction in the section of the passage in the upper part of the assembly. The section of the block of the head 43 of the absorber assembly 42 and the height of the maximum rise of this assembly 42 are then reduced relative to those possible with an assembly according to the invention such as that shown in FIG. 5. The control assemblies may be of the type shown in FIG. 5 and serve to stop the reactor urgently, or may be in the form of an absorber unit permanently connected during the operation of the reactor to the control rod whose displacement results in a greater or lesser great insertion of the absorber unit in the core to control the neutronic flux and the power of the reactor. In this case, as in the case of the urgent stoppage control assemblies, the upper part of the case of the fixed part of the assembly has through openings for the handling of the assembly and is not connected to the massive seizing member. The section of the passage of the absorber unit is therefore not reduced, and coresponds to the total section of the opening of the case 40 in its upper part. In this case, it is possible, as in the case of the urgent stoppage control bars, to raise the absorber unit to a height exceeding the interior of the fixed structure of the control assembly. In both cases, it is possible to raise the absorber unit to a height exceeding that of the assembly heads in the core. In this way, greater freedom is provided in the design of the core of the nuclear reactor. All of the control assemblies, as all of the fuel assemblies, have a foot part which is part of their fixed case, engaged in the bolster of the reactor by a prismatic surface cooperating with a corresponding prismatic surface of the bolster. This produces an orientation and a maintenance of the assemblies for achieving, when charging the core, perfect alignment between the openings of the assembly feet with the openings of the pillars of the bolster. The fuel assemblies such as that shown in FIGS. 3 and 4 may be of the fissile type or of the fertile type, depending on the composition of the fuel rods they enclose. It will be clear that the core of the nuclear reactor according to the invention may be constituted, when effecting the first charging of the reactor, by a simple operation of placing the fuel assemblies, each one in a position inside the core, in a position perfectly determined by the position of the corresponding pillar. Each of the assemblies is taken hold of by the grab whose claws are engaged in the openings extending through the upper part of the body of the assembly. The position of these openings in the body of the assembly enables it to be placed in a perfectly determined position below the handling device, as concerns its orientation about its verticaal axis. This orientation permits an introduction of the foot of the assembly in the pillar so that the corresponding prismatic surfaces of the assembly and the pillar are in concordance. When an assembly rests in the corresponding pillar of the bolster of the reactor, its orientation about its vertical axis is perfectly determined and permanently fixed so that the adjacent assemblies, whose orientation is likewise defined and fixed at the moment of their insertion in the corresponding pillars, come to place themselves automatically in a contiguous manner against the peripheral surfaces of the assembly. The corresponding orientation parts of the assembly and of the pillar also permit perfect alignment between the openings of the foot of the assembly and the openings of the pillar. All of the assemblies of the core, whether they be fuel, fissile or fertile, control assemblies or other types of assemblies, include means for orienting them relative to the bolster, and consequently to one another. It is therefore no longer necessary to provide special and complex machinings on the surface of the body of the assemblies or attached centering and orientation members, and the design and the construction of the assemblies are thus considerably simplified. The process of charging the first core of the reactor is itself considerably simplified, since it is no longer necessary to construct a core under air atmosphere with false assemblies prior to the effective charging of the core. The charging may be effected directly in the liquid sodium with true assemblies. Furthermore, the angular immobilization of the assemblies avoids any deformation or evolution of the core over a period of time under the effect of the stress undergone in service. The elimination of the self-orienting shoes of the assemblies relative to one another enables the connection between the foot and the prismatic case having a hexagonal section of the body of the assembly to be more simply designed. This connection may be achieved by a press operation instead of a welding operation, or a saving may be achieved as concerns the axial overall size of the assembly which may be taken advantage of for increasing the height of the fuel in each of the assemblies and therefore in the whole of the core. In the same way, the saving in the axial overall size of the body of the assembly due to the elimination of the seizing head enables the height to the fuel in each of the assemblies, and therefore in the whole of the core, to be increased. The elimination of the massive seizing head also permits a simplification of the design of the assembly as concern the calculation of its dimensions, its construction and the control of the connection between the hexagonal case of the body and the massive head. Generally, the simplications rendered possible permit a reduction in the quantities and therefore in the cost of the raw materials employed and a limitation in the production of waste products which are stored and retreated when discharging the core. The orientation means on the foot of the assembly and in the pillar of the corresponding bolster may have a shape different other than a prismatic shape having a hexagonal section. It is possible to use prismatic shapes of any section, male parts and corresponding female parts of any shape which are not symmetrical of revolution about the axis of the assembly and pillar, studs and openings of corresponding shapes or projecting parts and recesses capable of cooperating for ensuring the orientation and the immobilization of the foot of the assembly relative to the bolster. For the hooking and the orientation of the assembly by the handling grab, it is possible to use, instead of the through openings any other form obtained by a press or machining operation, bosses or hollows directly obtained on the hexagonal case. The materials and the surface treatments of the male and female parts of the orientation contact means are selected to avoid any attachment of material and any excessive wear both when the reactor is operating and when reactor discharging and charging operations are being carried out. The invention is applicable not only to fast neutron nuclear reactors but also to any nuclear reactor comprising a core formed by vertical fuel assemblies engaged by their foot in a support into which a reactor cooling fluid is sent.
039869253	description	Proceeding now to the detailed description of the drawings, there is illustrated a nuclear reactor 10, having a plurality of self-contained sections or portions such as 1, 1', 1" and others. Each reactor portion has its own nuclear fuel elements and control elements, subject to individual control as to each portion. However, neutron flux of the individual sections are inter-coupled due to proximity of disposition of the fuel element. Each reactor section pertains to a particular unit, 9 or 9' or 9" etc., serving individually as principal heat source for such a unit. Each unit, such as 9, includes its own closed circulation loop 20 for a heat exchange medium serving also as working fluid for MHD type electricity generation. Alkaline metal, such as sodium and/or potassium, circulates through loop 20. Nuclear reactor portion 1 is the principle heating source for the working fluid. Fluid leaving reactor portion 1 passes first through a two phase acceleration nozzle 2 with atomizer; next in the loop is a hollow jet condenser 3, feeding an inductively operating MHD-converter 4. Electric circuit lines 23 indicate schematically the withdrawal of electrical energy from the unit 9. Lines 23 are connected to a power output bus 33. Working fluid leaving MHD-converter 4 passes through a diffusor and shock condenser unit 8, to a heat exchanger 5, serving as cooling device for the principle working fluid in loop 20. A sub-loop 21 branches cooled working fluid off the main loop and couples same into the flow in the hollow jet condenser as part of the operation thereof. The principle return path passes through nozzle 2 for preheating of the working fluid. For the basic unit see, for example, "Electricity from MHD, 1968", Vol. III, page 1440 et seq., IAEA, Vienna 1968. The dashed line 22 in FIG. 1 denotes an open loop circulation path for air which passes through the heat exchanger 5 for receiving thermal energy from the working fluid, particularly for extracting residual thermal energy from the working fluid prior to entering the return branch of its circulation loop 20. Air is forced through loop 22 by means of a compressor 7 and passes through heat exchanger 5 to a gas turbine 6. The gas turbine extracts enthalpy from the air circulation and drives compressor 7. Gas turbine 6 and compressor 7 are combined as a driving aggregate of a type which is known from aerodynamics. As conceivably the air circulates in open loop, it is discharged from the turbine, for example, into a desalination plant 27, serving as prime heating medium for the desalination process. For this, the air flows for the several units 9, 9', 9" etc. are combined. The MHD working process that takes place in the system as shown in FIG. 1 is accompanied by temperature-entropy changes illustrated in the upper graph of FIG. 4. In FIG. 4 temperature T is plotted along the ordinate, entropy 5 is plotted along the abscissa on a suitable scale; the upper graph has particular validity for the working fluid in loop 20. Changes in state as between liquid and gaseous phases take place in the immediate vicinity of the characteristics of pure liquid (for the alkaline working fluid), and denoted as X = O (X) being the quality). Particularly, such changes of state occur partially in the liquid phase proper, partially in the wet steam area. Beginning with point d, that point defines the temperature-entropy state of the liquid metal as working fluid, upon leaving the nuclear reactor. The hot metal is depressurized in accelerator nozzle 2 along line d.fwdarw.e as continued along line e.fwdarw.f, whereby pursuant to the latter portion cooling is provided by means of already cooled, liquidious metal in the return branch 20' and having a relatively low energy content. The two phase stream is additionally cooled in hollow jet condenser 3, along line f.fwdarw.b, cooling resulting in a nearly complete condensation in the two phase flow. Cooling is provided particularly by operation of branch loop 21, returning some of the already cooled working fluid to the main stream. Pressure in the working fluid decreases throughout this process, while its kinetic energy is accordingly increased. Point b denotes entry into the MHD-generator 4 wherein energy is extracted from the fluid. The MHD-generator has windings for derivation of particular voltage and current. At this point, electrical energy is taken from the kinetic energy of the working fluid so that its temperature-entropy is not or only insignificantly changed. Subsequently, the working fluid is cooled in heat exchanger 5 the heat transfer being represented by branch b.fwdarw.a as to the working fluid in loop 20. Prior to heat exchange, as between air and working fluid, diffuser 8 regains pressure energy in the latter and thus completes, if necessary, condensation by a shock. Cooling of the working fluid in heat exchanger 5 and along line b.fwdarw.a is provided to render sufficiently cool fluid available for use in condenser 3, (sup-loop 2). The line b.fwdarw.c is almost identical with limit characteristics X = 0 and represents re-generative pre-heating of working fluid in nozzle 2 along a substantially isobaric characteristic. In other words, the branch b.fwdarw.c as to the returning working fluid is the heat exchange counter part for fluid entering nozzle 2 undergoing the change e.fwdarw.f. The working fluid re-enters the reactor at point c in the diagram, wherein it is heated and its state is changed to point d, completing the circulation. The lower portion of FIG. 4 illustrates, in a comparable scale, the concurrently occuring change of state of air as passing through heat exchanger 5. Air is compressed in the compressor 7 along the isentropic portion h.fwdarw.i. The air is heated (branch i.fwdarw.k) through heat exchange with the principal working fluid of the system. As to the working fluid, that corresponds to branch b.fwdarw.a. The air is decompressed in turbine 6 along the isentropic curve k.fwdarw.i and, possibly cooled, along line l.fwdarw.h. That latter branch is present only in case of a closed loop air circulation but is omitted for open loop circulation. The hot air at point 1 can be discharged, for example, into the desalination plant, and cool air (point h) may enter the system from the environment. Turning now to particulars of FIG. 2, an individual unit includes essentially all of the components as shown in FIG. 1 in form of a serial arrangement. The nuclear reactor 10 of the system as a whole is, therefor, divided into a plurality of subreactors such as 1, 1', 1", disposed respectively in the rear of each unit. The units are elongated in construction and extend parallel to each other. The reactor portions are aligned transversely to that direction of predominant extension of each unit. The particular two-phase nozzle 2 is disposed behind the fuel elements of subreactor 1'. Next in line is the hollow jet condenser 3, inductive MHD-converter 4, diffusor and shock-condenser 8 for self-energization, and heat exchanger 5 driving aggregate 11. All these components constitute a structural unit. As the other units, such as 9', 9", are similarly constructed, similar components are aligned transverse to the predominant extension of each unit. Elements 14, 15 and 18 provide shielding that encases the entire system. Unit 9 has power cable 23, unit 9' has a cable 23', unit 9" a cable 23" etc.; these cables are all connected in parallel and to the common bus system 33 that constitutes the electrical output of the plant. Reference numeral 13 denotes the control cable for unit 9 which includes signal lines providing signal in representation of the particular operational state of unit 9. There being similar cables 13', 13" and others respectively for units 9' and 9" and others. These signal lines included in cables 13 and others feed a process control computer 25, individually controlling the reactor and MHD-generator portions in accordance with a program that depends on the demand for power on bus 33. The control signals pass from the computer to the several units via control lines included in the several cables 13, 13' etc. The front end of each unit has a tube, such as tube 12 of unit 9. Cables 13 and 23 pass through tube 12. Additionally, cool air enters the system through tube 12. Hot air is discharged from unit 9 through opening 17. The arrows in the opening denote the path of air flow in the system. Hot air discharged from the several units combines in a collection chamber 26 and flows through openings to desalination plant, or chemical plant 27, for heating therein. FIG. 3 illustrates what can be described to be a cross section through a bundle of units of the type shown in FIG. 2 and arranged in a compact, honeycomb-type arrangement. The wall structure 19 establishes suitable support for the several units. The individual units are to some extent known per se as to their particular contribution to the operation as a whole. The invention resides in the construction of a power plant from such units as self-contained units with regard to the MHD-process. They ae electrically connected in parallel and their nuclear process is controlled, for example, by electronic computer 25, to optimize operation as to power requirement. Utilization of air as cooling medium for removal of thermal energy from the principal circulation yields a high degree of independence of the locaton of the power plant. Aggregate 11 comprised of gas turbine 6 and compressor 7 provides air at an elevated pressure to improve heat transfer from the working fluid so as to reduce the need for large cooling surfaces. The power for the compressor is produced in the gas turbine using residual thermal energy extracted from the circulating stream of alkaline working fluid (characteristics b.fwdarw.a and i.fwdarw.k). Each unit has its own aggregate so that the several units as they operate in parallel, are decoupled as to cooling. Cooling of each unit can be controlled to match the requirements for cooling of a particular unit in dependence upon its power output. The several units in a single power plant are coupled to each other three fold. First, neutron flux of the subreactor units 1, 1', 1" etc. is shared due to proximity. Secondly, the units operate on a common power bus 33. Thirdly, the control of the units is interrelated in accordance with a particular program. Each unit has two operational modes. In the cooling mode the respective MHD-converter takes electrical energy from the electrical circuit to pump liquid working fluid as cooling medium through the reactor, i.e., such a unit acts as a load on bus 33 and causes the working fluid to circulate through its loop. In the cooling mode the production of thermal energy in the particular reactor portion is rather low, too low to permit useful extraction of electrical energy from the MHD-generator. The second mode is the power mode in which electrical energy is produced by and can be taken from the unit when operated in that mode. A unit operated in the power mode can be shifted into the cooling mode through control of neutron flux in the particular unit. That control is particularly provided by the computer 25. In case the power requirement on bus 33 increases, a unit that is currently operated in the cooling mode can be shifted into the power mode, to participate in the production of electrical energy. The neutron flux decreases in the border zone of the reactor (e.g. in units 1'). This "natural" distribution in neutron flux is utilized by having the outer units operate under stand-by conditions to be normally in the cooling mode. A power plant controlled in such a manner operates particularly advantageous in comparison with a conventional power plant, as neither heavy masses such as rotors, flywheels, etc., nor stored energy steam volumes have to be considered upon change in power requirements. Thus, the response delay as to control operation of the system in accordance with the invention is considerably reduced, which, in turn, means that the power output of the plant may follow promptly even comparatively large, suddenly occuring variations in power requirements. It will be recalled that the electronic computer 25 supervises the reactors and MHD-converters in a process control operation and in dependence upon the power requirement. The program alluded to above refers specifically to the selection of power mode-cooling mode for the several units and to the selection of which unit is to undergo a change in mode. Another advantage of the invention is to be seen in the high degree of independence of each unit. Therefor, in case a defect occurs in one of them, the plant does not have to be shutdown as a whole. Instead, through appropriate control operations, the particular defective unit can be shutdown and replaced. The units do not only operate but are also constructed and manufactured as individual replacement units. Spare units may be kept as inventory, so that in case one of them is found to be defective, it can be replaced as a whole by readily available new one, while the removed, defective one is repaired. This, in turn, increases the availability of the plant as a whole, as the plant is not fully operationally only for the time it takes to replace a unit. If the plant has many units that exchange diminishes the available plant output only by a fraction of total output which is noticeable only if the plant operates at maximum capacity. On the other hand, testing as well as production of such units is simplified, as compared with conventional equipment. Also, rating of a power plant differs from others of similar construction merely in the number of units employed. The honeycomb arrangement, as shown in FIG. 3, permits not only indefinite increase extension of a plant, but different size plants are compact so as to differ little in overall size. The invention is not limited to the embodiments described above but all changes and modifications thereof not constituting departures from the spirit and scope of the invention are intended to be included.
	claims	1. Imaging apparatus comprising:a radiation source for generating an imaging beam;a detector responsive to the imaging beam to generate image signals and comprising an array of pixels arranged in rows and columns, each pixel being responsive to incident radiation to generate an output signal;a drive arranged to move the radiation source and the detector relative to a subject in a scanning direction;an adjustable collimator arranged to vary the width of the imaging beam in the scanning direction; anda control system responsive to adjustment of the collimator to combine the output signals of groups of pixels comprising greater numbers of pixels automatically as the collimator is adjusted to increase the width of the imaging beam in the scanning direction, thereby to increase the contrast resolution of the image signals for a given spatial resolution. 2. Apparatus according to claim 1 wherein each group of pixels defines a super pixel comprising an array of fundamental pixels, the number of fundamental pixels in the array being selected according to a corresponding collimator setting. 3. Apparatus according to claim 2 wherein the relationship between collimator settings and the number of fundamental pixels in an array defining a super pixel is stored in a lookup table and related to respective ones of a plurality of different x-ray procedures. 4. Apparatus according to claim 1 wherein the control system is arranged to measure the signal level of the detected imaging beam and to adjust the collimator slit width to maintain the detected signal level at or close to a desired setpoint. 5. A method of operating imaging apparatus of the kind having a radiation source and an associated detector which are moveable relative to a subject, the method comprising:generating an imaging beam from the radiation source;moving the radiation source and the detector relative to a subject in a scanning direction to generate output signals from each of a plurality of pixels of the detector;adjusting a collimator to vary the width of the imaging beam in the scanning direction;detecting the setting of the collimator; andcombining the output signals of groups of two or more pixels according to the setting of the collimator, thereby to optimize a selected characteristic of the image signals. 6. A method according to claim 5 comprising combining the output signals of groups of pixels comprising greater numbers of pixels as the collimator is adjusted to increase the width of the imaging beam in the scanning direction, thereby to increase the contrast resolution of the image signals for a given spatial resolution. 7. A method according to claim 5 wherein each group of pixels defines a super pixel comprising an array of fundamental pixels, the number of fundamental pixels in the array being selected according to a corresponding collimator setting. 8. A method according to claim 5 wherein the relationship between collimator settings and the number of fundamental pixels in an array defining a super pixel is stored in a lookup table and related to respective ones of a plurality of different x-ray procedures. 9. A method according claim 5 including measuring the signal level of the detected imaging beam and adjusting the collimator slit width to maintain the detected signal level at or close to a desired setpoint. 10. A collimator for adjusting the effective width of an imaging beam generated by a radiation source, the collimator comprising:first and second shutter elements arranged side by side and including respective first and second tapered surfaces, and further including respective first and second slit-forming surfaces forming therebetween a slit through which radiation emitted by the source can pass, the slit having a length and a width of shorter dimension than the length, the width defined by a distance between the slit-forming surfaces;a guide mechanism comprising first and second tapered surfaces arranged to cooperate with respective ones of the first and second tapered surfaces on the first and second shutter elements; anda drive mechanism arranged to produce first sliding movement between the first tapered surface of the first shutter element and the first tapered surface of the guide mechanism, and second sliding movement between the second tapered surface of the second shutter element and the second tapered surface of the guide mechanism, to cause the first and second slit-forming surfaces to move relative to one another in the direction of the slit's width to vary the dimension of that width. 11. A collimator according to claim 10 wherein the imaging beam is directed towards a detector, the drive mechanism comprising a single motor that produces both of the first and second sliding movements, wherein both of the shutter elements are arranged to move co-centrically with respect to a centre line that passes through the slit along the slit's length, to obtain an optimum umbra to penumbra ratio of the imaging beam on the detector. 12. A collimator according to claim 10 wherein each shutter element comprises a strip of radiation-opaque material defining the respective slit-forming surface, and a supporting body carrying the respective strip and defining the respective tapered surface. 13. A collimator according to claim 10 wherein the drive mechanism comprises a motor, a reduction drive connected to the motor, and a mechanism connected to the reduction drive and arranged to impart linear motion to both shutter elements to effect the first and second sliding movements. 14. A collimator according claim 10 wherein the motor comprises a solenoid. 15. A collimator according claim 10 wherein the first and second tapered surfaces of the first and second shutter elements are biased towards one another, wherein the drive mechanism is operable to move those first and second tapered surfaces away from one another against the bias.
	description	This application is a continuation of U.S. patent application Ser. No. 12/257,750 filed on Oct. 25, 2008 which claims the priority benefit of U.S. Provisional Patent Application No. 60/982,628 filed on Oct. 25, 2007, the disclosure of which is expressly incorporated herein it its entirety by reference. Not Applicable Not Applicable The field of the present invention generally relates to overhead hoist or crane systems and, more particularly, to such systems for transporting canisters of spent nuclear fuel. Spent nuclear fuel is typically transferred in canisters which are moved by overhead hoist or crane systems. For example, see U.S. Pat. Nos 6,674,828 and 6,788,755, the disclosures of which are expressly incorporated herein in their entireties by reference. The spent nuclear fuel remains highly radioactive and is capable of generating significant thermal energy. Therefore, the canisters are typically transferred within a shielded bell. While prior hoist systems may adequately transfer the spent fuel canisters, they can be rather complex and expensive to produce and operate. The hoists must have a relatively high rating because it must raise both the spent fuel canister and the shield bell at the same time. For example, a hoist may need to be rated for 200 tons when the maximum weight of the spent fuel container is only 70 tons. Additionally, the hoist must have the ability to automate and have accurate reliable positioning to engage and manipulate the spend fuel canister. Accordingly, there is a need in the art for an improved system and method for transporting canisters of spent nuclear fuel. The present invention provides a system and method for transporting canisters of spent nuclear fuel that solve at least problem of the related art. According to one embodiment of the present invention, a transfer system for moving a spent fuel canister comprises, in combination, a carrier, a shielded bell trolley movable along the carrier and carrying a shielded bell, and a canister trolley movable along the carrier and carrying a lifting mechanism for raising and lowering the spent fuel canister into and out of the shielded bell. The canister trolley can move along the carrier independent of the shielded bell trolley. According to another embodiment of the present invention, a transfer system for moving a spent fuel canister comprises, in combination, a carrier, a shielded bell trolley movable along the carrier and carrying a shielded bell, and a canister trolley movable along the carrier and carrying a lifting mechanism for raising and lowering the spent fuel canister into and out of the shielded bell. The carrier directly supports the shielded bell trolley so that the lifting mechanism does not support the shielded bell. According to yet another embodiment of the present invention, a transfer system for moving a spent fuel canister comprises, in combination, a bridge, a shielded bell trolley movable along the bridge and carrying a shielded bell, and a canister trolley movable along the bridge and carrying a hoist for raising and lowering the spent fuel canister into and out of the shielded bell. The bridge includes a first pair of spaced-apart rails for supporting the canister trolley and a second pair of spaced-apart rails for supporting the shielded bell trolley. The first pair of spaced-apart rails is substantially parallel to the second pair of spaced-apart rails. The bridge is movable along a third pair of spaced-apart rails substantially perpendicular to the first pair of spaced-apart rails and the second pair of spaced-apart rails. The canister trolley can move along the bridge independent of the shielded bell trolley and the shielded bell trolley can move along the bridge independent of the canister trolley. From the foregoing disclosure and the following more detailed description of various preferred embodiments it will be apparent to those skilled in the art that the present invention provides a significant advance in the technology of system and method for transporting canisters of spent nuclear fuel. Particularly, the invention provides a relatively low cost system which meets performance requirements. Additional features and advantages of various preferred embodiments will be better understood in view of the detailed description provided below. It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various preferred features illustrative of the basic principles of the invention. The specific design features of the canister transfer systems as disclosed herein, including, for example, specific dimensions, orientations, and shapes of the various components will be determined in part by the particular intended application and use environment. Certain features of the illustrated embodiments have been enlarged or distorted relative to others to facilitate visualization and clear understanding. In particular, thin features may be thickened, for example, for clarity or illustration. All references to direction and position, unless otherwise indicated, refer to the orientation of the transfer systems illustrated in the drawings. In general, up or upward refers to an upward direction generally in the plane of the paper in FIG. 1 and down or downward refers to a downward direction generally in the plane of the paper in FIG. 1. It will be apparent to those skilled in the art, that is, to those who have knowledge or experience in this area of technology, that many uses and design variations are possible for the transfer systems and methods disclosed herein. The following detailed discussion of various alternative and preferred embodiments will illustrate the general principles of the invention with reference to a transfer system for spent nuclear fuel canisters. Other embodiments suitable for other applications will be apparent to those skilled in the art given the benefit of this disclosure. Referring now to the drawings, FIGS. 1 and 2 shows a canister transfer system 10 according to a preferred embodiment of the present invention. The operating envelope of the illustrated canister transfer system 10 provides coverage of a transportation cask transfer cell, waste package transfer cell, canister staging cells, and transfer system maintenance/staging area. The illustrated canister transfer system 10 includes a carrier 12, a first or shielded bell trolley 14 movable along the carrier 12 and carrying a shielded bell 16, and a second or canister trolley 18 movable along the carrier 12 and carrying a lifting mechanism 20 for raising and lowering the spent fuel canister 22 (see FIG. 9) into and out of the shielded bell 16. The illustrated canister transfer system 10 is in the form of a bridge crane, wherein the carrier 12 in the form of a bridge 24. It is noted that the canister transfer system 10 can alternatively have any other suitable form and/or the carrier 12 can alternatively have any other suitable form. The illustrated bridge 24 includes end trucks riding on a pair of laterally spaced apart and parallel rails 26. The illustrated rails 26 are straight but it is noted that any other suitable configuration for the rails 26 can be utilized. The illustrated rails 26 supported by corbels 28 located on laterally spaced-apart walls 30. It is noted that any other suitable supports for the rails 26 can alternatively be utilized. The distance between the rails 26 can be any suitable distance such as, for example, about eighty six feet. The illustrated bridge 24 is formed by box frame girders 32. Girder plates are preferably continuous welded for maximum strength, stiffness, and torsional stability but can alternatively be constructed in any other suitable manner. Bumpers 34 are provided at the ends of the rails 26 which are designed to minimize impact to the canisters 22 being transferred. Each bridge girder 32 supports the two trolleys 14, 18. A first or inner pair of rails 36 is provided for the canister trolley 18 and a second or outer pair of rails 38 is provided for the shielded bell trolley 14. The rails 36, 38 are preferably fastened to the girders 32 with welded clips but can alternatively be secured in any other suitable manner. The rails 36, 38 are mounted on top of the girders 32 so that the bridge 24 directly and independently supports each of the two trolleys 14, 18. The illustrated first pair of spaced-apart rails 36 is substantially parallel to the second pair of spaced-apart rails 38. The illustrated first and second pairs of rails 36, 38 extend in the lateral direction, that is along the longitudinal length of the bridge 24, such that the first and second pairs of rails 36, 38 are substantially perpendicular to the rails 26 for the bridge 24. The illustrated first and second pairs of rails 36, 38 are each straight but it is noted that any other suitable configuration for the rails 36, 38 can be utilized. The illustrated first and second pairs of rails 36, 38 are located at the same height but can alternatively be located at other heights as described in more detail hereinafter. The canister or main hoist trolley 18 includes a frame or body 40 having a plurality of wheels 42 which cooperate with the rails 36 so that the canister trolley 18 can be selectively moved along the rails 36. The canister trolley 18 can have any suitable type of drive mechanism for the wheels 42 such as, for example, an electric motor. The illustrated canister trolley 18 rides on the inner rails 36 of the bridge 24 and is preferably provided with seismic restraints. The canister trolley 18 also includes the lifting mechanism 20 for performing various transfer operations including raising and lowering the canisters 22. The illustrated lifting mechanism 20 is a crane or hoist system 44 having a remote grapple attachment or system 46. It is noted that any other suitable type of lifting mechanism 20 can alternatively be utilized. The crane or hoist 44 preferably utilizes failure proof technology. The illustrated hoist 44 includes an upper block assembly 48 and a lower block assembly 50 that is suspended from the upper block assembly 52 by a reeving arrangement 52. Operation of an electric motor raises and lowers the lower block 50. Secured to the lower block assembly 50 is the grapple attachment 46 which is adapted to interact with the shielded bell 16 and the canisters 22 as described in more detail hereinafter. The remotely operated grapple attachment 46 preferably utilizes limit switches to verify grapple engagement. The grapple attachment 46 preferably utilizes a mechanism that includes a mechanical safe drive that will not allow the grapple attachment 46 to disengage when a load is suspended from the grapple attachment 46. The canister trolley 18 can have any suitable hoisting capacity such as, for example, seventy tons. Electrical power to the canister trolley 18 is provided through hard-wired connections using a cable track system. The illustrated shielded bell 16 is generally cylindrical shaped and has an inner wall 54 which forms an interior space or main shielding chamber 56. The illustrated shielded bell 16 has a pair of opposed lifting lugs or trunnions 58 near its top end which are used by the trolley 14 to hold the shielded bell 16. The shielded bell 16 be can have any suitable size such as, for example, a height of about twenty-five feet, an outside diameter of about ninety-four inches, and an inside diameter of about seventy two inches. The shielded bell 16 can be formed of any suitable material such as, for example, steel and preferably reduces radiation exposure to operating personnel by limiting the contact dose rate (exterior of the shielded bell 16) to about one hundred mrems/hr. The total weight of the shielded bell 16 supported by the shielded bell trolley 14 can be, for example, about two hundred tons. The bottom end of the illustrated shielded bell 16 can be attached to a chamber 60 to accommodate cask lids having diameters of, for example, up to eighty-four inches. A bottom plate 62 with an opening can be attached to the chamber to support a motorized shield gate 64. The bottom plate 62 can have a thickness of, for example, about nine inches and the opening can have a diameter of, for example, about eighty six inches. The shield gate 64 can have a thickness of, for example, about twelve inches. The sliding shield gate 64 provides bottom shielding for the canister 22 once the canister 22 is inside the shielded bell 16. A shielded skirt 66 is provided around the perimeter of the bottom plate 62 which can be raised and lowered with the help of mechanical actuators. The shield skirt 66 is used to close any gap between the bottom plate 62 and a floor surface 68 to prevent any lateral radiation shine during a canister transfer operation. The shielded skirt 66 can have a thickness of, for example, about nine inches. The bottom plate 62 can preferably be located about two inches above the concrete floor 68 where canister transfer ports are located. The shielded bell trolley 14 supports the shielded bell 16 and includes a frame of body 70 having a plurality of wheels72 which cooperate with the rails 38 so that the shielded bell trolley 14 can be selectively moved along the rails 38. The shielded bell trolley 14 can have any suitable type of drive mechanism for the wheels 72 such as, for example, an electric motor. Electrical power to the shielded bell trolley 14 is provided through hard-wired connections using a cable track system. The shielded bell trolley 14 also includes grapple means 74 for interacting with the shielded bell 16. The illustrated grapple means 74 is in the form of a pair of paddles secured directly to the trolley frame 70. The paddles 74 include openings for receiving the trunnions 58 of the shielded bell 16. It is noted that the grapple means 74 can alternatively be of any suitable type. It is also noted that if desired the shielded bell trolley 14 can alternatively include a crane or hoist such as that described in U.S. patent application Ser. No. 11/839,797, the disclosure of which is expressly incorporated herein in its entirety by reference. The illustrated shielded bell trolley 14 rides on the outer rails 38 and supports the shielded bell 16 which includes the main shielding chamber 60 for shielding canisters 22, a lower larger chamber 76 for accommodating cask lids 78, and the slide gate 64 for providing bottom shielding for canisters 22 when inside the shielded chamber 60. The shielded bell trolley 14 carries the entire load of the shielded bell 16 and the bridge 24 directly supports the shielded bell trolley 14 so that the hoist system 44 of the canister trolley 18 is never required to support the shielded bell 16. The load path for the shielded bell 16 does not pass through the hoist system 44 or the canister trolley 18. This enables the hoist system 44 of the canister trolley 18 to be sized smaller than if it must carry the load of the shielded bell 16. For example, a seventy ton hoist 44 can be utilized when the shielded bell 16 weighs about two hundred tons or more. The shielded bell trolley 14 is preferably provided with seismic restraints. The trunnion-type attachment of the shielded bell 16 to the shielded bell trolley 14 preferably forma a swivel type joint to minimize transmission of seismic load to the trolley frame 70. All hoist, trolley and bridge drive gearing is preferably enclosed in sealed gear boxes, with oil of high flash point such as four hundred degrees Fahrenheit or better, that will not support a flame or fire. Electric power is provided by a crane cable track system 80 located along the runway length and supported by the facility walls 30. The canister trolley 18, the hoist system 44, and the shielded bell trolley 14 are each preferably controlled from a control room with a local control station as a backup. Limit switches, load cells and interlocks are preferably provided for the operation of the two trolleys 14, 18. The illustrated canister transfer system 10 allows for the two trolleys 14, 18 to move independently of one another when desired and to be selectively interlocked together to operate as a single unit when performing selected canister transfer operations. To mechanically interlock the trolleys 14, 18 together, the canister trolley 18 with the grapple 46 is first positioned concentric with the shielded bell 16, wherein the central axis of the grapple 46 is aligned with the central axis of the shielded bell 16. The two trolleys 14, 18 are mechanically interlocked locked prior to starting a canister transfer operation by lowering the grapple 46 into the shielded bell 16. It is noted that the trolleys 14, 18 can alternatively be mechanically interlocked in any other suitable means. FIGS. 3 to 5 illustrate a canister transfer system 100 according to second embodiment of the present invention. The second embodiment of the canister transfer system 100 illustrates that the shielded bell trolley 14 can be in an under running position. Either an over running or under running configuration can be utilized depending on the total allowable head room for the application. The illustrated rails 38 for the shielded bell trolley 14 are located outward and below the rails 36 for the canister trolley 18. Located above the shielded bell trolley 14 is the canister trolley 18 which operates independently of the shielded bell trolley 14 and has a telescoping mast 102 with a universal nose that can be attached to various tools for the work that needs to be performed. A tool box 104 for the tools can be located at an end of the shielded bell trolley 14. FIGS. 6 to 9 illustrate a transfer system 200 according to third embodiment of the present invention. The third embodiment of the canister transfer system 200 illustrates that the shielded bell trolley 14 can be located inward of the canister trolley 18. The illustrated rails 38 for the shielded bell trolley 14 are located inward and below the rails 36 for the canister trolley 18. Located above the shielded bell trolley 14 is the canister trolley 18 which operates independently of the shielded bell trolley 14. A typical canister transfer operation using the canister transfer system 10, 100, 200 includes positioning the shielded bell 16 over a port on a concrete deck or floor 68 with the shielded bell bottom being about two inches above the deck 68. Below the concrete deck 68 is a shielded transfer cell 76 with the port located above a loaded storage cask 82. In a similar manner, an empty waste package is positioned under an adjacent port of the waste package transfer cell. Each port is equipped with a motorized shielded gate and flushed with concrete deck surface. The transfer operation typically begins by positioning the canister transfer system 10 over the port with the loaded storage cask 82. The shield skirt 66 is remotely lowered to rest on the deck 68 to prevent any lateral radiation shine. The shielded slide gate 84 on the concrete deck 68 is opened to access the cask lid 78 located below. The slide gate 64 of the shielded bell 16 is opened and the grapple 46 is lowered through the shielded bell 16. The grapple 46 is engaged with a mounted lift fixture on the cask lid 78. The cask lid 78 is raised into the larger chamber 78 of the shielded bell 18. The deck slide gate 84 is closed and the shield skirt 66 is raised. The canister transfer system 10 is moved and positioned over a cask lid staging area located on the concrete deck. The cask lid 78 is lowered and placed in the staging area and the grapple 46 is raised. The canister transfer system 10 is moved back over the port with the loaded storage cask below 82, and the canister transfer system 10 is positioned and aligned for canister pickup and the shield skirt 66 of the shielded bell 16 is lowered. The deck slide gate 84 is opened and the grapple 46 is lowered to engage the canister lifting feature. The canister 22 is pulled up into the shielding chamber 56 and shielded bell 16. Both the transfer system slide gate 64 and the deck slide gate 84 are closed. The shield skirt 66 of the shielded bell 16 is raised and the canister transfer system 10 is moved over the waste package port for canister loading. The canister transfer system 10 is positioned and aligned with the port and the shield skirt 66 of the shielded bell 16 is lowered. Both the shielded bell and deck slide gates 64, 84 are opened. The canister 22 is lowered and placed into the waste package. The grapple 46 is then disengaged from the canister 22 and removed in a reverse manner. It is apparent from the foregoing disclosure that the canister trolley 18 can traverse the bridge 24 independently of the shielded bell trolley 14. This permits the canister trolley 18 to travel to and from the tool crib 104 located on the shielded bell trolley 14 to retrieve various tools and grapples required for removing the spent fuel canisters 22 from one storage cask 82 and transferring them to another. The canister trolley 18 is used to lift the canisters 22 as well as handling of tools and lift grapples required to remove and replace the cask lids 78 and to move the spent fuel canisters 22. Additionally, the canister trolley 18 can interlock with the shielded bell trolley 14 so that the canisters 22 can be transferred from one cask 82 to another cask while the shielded bell 16 protects the area from radiation given off by the spent fuel canisters 22. It is also apparent from the above disclosure that the hoist system 44 does not carry the shielded bell 14. Thus the hoist 44 does not have to be rated for more than the capacity of the heaviest spent fuel canister 22 because it does lift or lower the shielded bell 16. It is further apparent from the above disclosure that the canister extraction process can be automated. Leaving the shielded bell 16 in a fixed position and moving the canister trolley 18 with respect to a fixed position enables the canister trolley 18 and the hoist 44 to be very accurate and reliable when the bridge 24 does not have to move. Thus, the canister trolley 18 is isolated from the shielded bell 16 allowing them to move independently without one limiting movement of the other and when necessary the two are linked together to provide the accuracy needed to extract and manipulate spend fuel containers 22. From the foregoing disclosure and detailed description of certain preferred embodiments, it will be apparent that various modifications, additions and other alternative embodiments are possible without departing from the true scope and spirit of the present invention. The embodiments discussed were chosen and described to provide the best illustration of the principles of the present invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such modifications and variations are within the scope of the present invention as determined by the appended claims when interpreted in accordance with the benefit to which they are fairly, legally, and equitably entitled.
051026147	claims	1. A method for underwater welding of a control rod drive housing inserted through a stub tube to maintain requisite alignment and elevation of the top of the control rod drive housing to an overlying and corresponding aperture in a core plate as measured by an alignment device which determines the relative elevation and angularity with respect to the aperture, comprising the steps of: providing a welding cylinder dependent from the alignment device such that the elevation of the top of the welding cylinder is in a fixed relationship to the alignment device and is gas-proof; pressurizing the welding cylinder with inert welding gas sufficient to maintain the interior of the welding cylinder dry; lowering the welding cylinder through said aperture in said core plate by depending said cylinder with respect to said alignment device, said lowering including lowering through and adjusting the elevation relationship of the welding cylinder to the alignment device such that when the alignment device is in position to measure the elevation and angularity of the new control rod drive housing, the lower distal end of the welding cylinder extends below the upper periphery of the stub tube where welding is to occur; inserting a new control rod drive housing through the stub tube and positioning the control rod drive housing to a predetermined relationship to the anticipated final position of the control rod drive housing; providing welding implements transversely rotatably mounted interior of the welding cylinder relative to said alignment device such that the welding implements may be accurately positioned for dispensing weldment around the periphery of the top of the stub tube and at the side of the control rod drive housing; measuring the elevation and angularity of said control rod drive housing; and dispensing weldment along the top of the stub tube and at the side of the control rod drive housing. monitoring the elevation and angularity of the top of the control rod drive housing during said dispensing step. 2. The process of claim 1 and including the step of
062563637	abstract	A transport/storage container for spent nuclear-fuel elements has a vessel having a side wall with an inner surface defining an interior extending along an axis and a plurality of like basket sections forming a stack extending substantially a full axial length of the interior and forming a plurality of axial full-length rectangular-section wells adapted to receive the spent fuel elements. Each of the basket sections is formed of two long light-metal neutron-absorbing plates crossing each other, each having a pair of outer ends directly engaging the inner surface of the side wall in heat-transmitting contact therewith, and subdividing the interior at the respective section into a plurality of segments. A plurality of short light-metal neutron absorbing plates are fitted together in each of the segments and form with the main plates of the respective section rectangular-section axially throughgoing openings forming the wells with the plates of the other sections.
	summary
	description	The invention concerns a method and a system for recording the results of a psychological test. In particular it concerns a method and a system for recording the results of a test for personnel assessment by at least one observer. Nowadays tests are carried out in the most widely varying sectors, for assessment of the emotional and intellectual capabilities of people. Particular commercial significance is attributed to psychological tests of that kind in terms of the assessment of various applications for a post in a corporation, that is to say in terms of personnel assessment. Assessing applicants for posts in large corporations and in particular for management positions is nowadays increasingly performed in establishments which are internationally referred to “assessment centers”. An assessment center serves for assessing and evaluating the capabilities and competences of individual applicants on the basis of acknowledged, proven psychological tests. Assessment centers are generally divided into a number of areas in which different tests are carried out. Such tests are for example role playing, plan games, group discussions, individual presentations, case studies and psychological test procedures. In that respect the candidates are observed in situations (practice exercises) which are intended to reproduce as well as possible the demands of the future job. A number of observers record the behavior of the participants in each situation by means of observation sheets. Various capabilities and qualities of each participant are assessed by the observers. The various requirements involved are evaluated on a scale, which permits the various participants to be compared to each other. The scaling further permits to observe differences in performance of individual candidates in various practice situations. For this purpose the observers generally make use of prepared observation sheets on which assessments and observations are entered in manuscript. The recorded data are brought together in the context of what is referred to as an observer conference and assembled to afford a definitive evaluation of the applicant. While computer-aided tests have proven their worth for recording the intellectual capabilities and the level of education of the applicants, for example for recording knowledge of mathematics, knowledge of natural sciences or knowledge of languages, in practice no automated methods have proven to be so powerful and informative in regard to the assessment of the characteristic qualities and psychological competitiveness of the applicants, as assessment of the behavior of applicants by trained observers in practice situations. Automatic methods of standardizing and comparing the data relating to individual applicants are also known, without in that respect addressing the procedure of obtaining information, that is to say recording of the test results by at least one observer. Thus for example US 2002/0055870 describes a method and an apparatus for the comparison of personnel evaluations with evaluation requirements. The procedure involved in acquiring data, in particular personnel assessment, by psychologically trained observers, is here scarcely addressed. The procedure is substantially based on the data which the applicant himself provides about himself. A fully automatic inquiry system and method is to be found in WO 02/21303. This method may permit automatic processing of the results of interviews conducted by way of a computer and thus rapid evaluation of a large number of inquiry results. In contrast the informativeness and reliability of individual questioning procedures and tests by psychologically trained observers is not achieved here. A similar consideration applies to the apparatus of WO 02/13095. Here, associated with automatic answer recording are automatic prediction means which are intended to ascertain the suitability of individual applicants for a post. WO 03/009187 describes an Internet-based personnel assessment system. Here, requirement profiles of the employers and test results from the personnel consultants are brought together by way of the Internet. The applicants also have access to that system. This document describes in detail the production of requirement profiles and comparison thereof with evaluation profiles in order as a result to establish a conformity therebetween. The question of recording the performances and evaluation profiles of the applicants is less thoroughly considered. It is proposed that for example technical scientific knowledge is recorded by an online test. The document also refers to the consideration that some areas of competence of the applicant must be recorded at a personal conversation referred to therein as an interview. The results of this interview, after the end of the interview, are entered in a profile which is stored on a computer, of the applicant. The document does not deal with the question of how the evaluation profiles are recorded during an interview by a psychologically trained personnel consultant. One object of the invention is to provide a method and a system for recording the results of a psychological test, which promotes execution of the test and the significance of the test results. That object is attained by a method having all of the features of the presently described methods. As a departure from the usual practice of recording in manuscript the test results noted by the observer, the operation of recording the results is implemented by using a computer, on the display of which are produced input fields in which the results can be entered to be stored in a data memory. That already considerably increases the availability of the results. Thus, an overseer or supervisor can already get to know the impression of the observer or observers while the test is being conducted, by looking at the stored results. In addition the computer automatically executes functions of result recording and/or test implementation. In a first practical embodiment the computer records the running time of the test, that is to say the time which has elapsed since the beginning of the test. By virtue of this time recording operation, together with an entry in an input field, the test time which has expired at the moment of the entry can be stored by means of the computer. The time of the test which is associated with an entry provides a high level of information both about the applicant and also about the observer. Qualities which the observer enters at an early time appear obvious to the observer. Thus self-confidence and competent appearance of an applicant which are recognized at an early time may have a different importance with respect to certain employment prerequisites than the same self-confidence and competence which is noticed only in the course of a longer interview. The value of an entry can therefore be weighted with the automatically recorded time value. It will be noted that entries at an inopportune time can also give information about premature or defective assessment. Certain qualities and attributes of a person being tested can be reliably determined only at the end of a given test period. If entries relating to those features are made at an early time, it is possible to deduce therefrom that the observer was rash in arriving at his assessment. In an embodiment of the invention, for results which may be recorded only after a given test time has elapsed, the computer may enable the input fields in question, for receiving an entry, only after a predetermined time. The result relating to a given criterion, in particular a qualification or a quality of a person being tested, can be recorded in accordance with one embodiment of the invention in the form of a scaled value. A scaled value is generally a value which is between a minimum value and a maximum value. When assessing certain properties of persons being tested, it may be useful for example for evaluations to be recorded in six different steps of far above average (=6) to far below average (=1). In a practical embodiment those results which are recorded in the form of a scaled value, in relation to a given criterion, can be recorded on a plurality of occasions at different times. The sum of all results associated with the specified criterion can be divided by the number of inputs, thereby forming the arithmetic mean of all inputs. That procedure, in relation to a given criterion, not only records the result which is established towards the end of the test by the observer. In relation to that criterion, results are also recorded at the beginning of the test and during the course of the test. That result recordal which is distributed over the course of the test counteracts an effect which occurs when recording only the final result. If it is only the final result that is recorded, then it is generally the last impression gained by the observer that predominates. Recording the result during the course of the test means that the impressions of the observer at the beginning of the test and in the middle of the test are also sufficiently taken into account. In addition the number of entries in relation to a given criterion can allow conclusions to be drawn as to the strength of the impression of an observer, in relation to that given criterion. In practice the results which are inputted in relation to each given criterion can be stored together with the moment in time of the input thereof. That makes it possible on the one hand to associate a given assessment with given moments in the test. In addition, assessment of the behavior of the observer is also made possible. On the one hand, the entries and the times of the entries of various observers can be compared. In particular entries which are made almost simultaneously by a number of observers enjoy particular significance. Observers, whose observations differ greatly from those of other observers, can be trained on the basis of those items of information. That is possible in particular when the computerized result recordal procedure is coupled and synchronized with a video recording of the test so that the observers can associate the times of their entries with specific events in the test procedure, which are established on the video recording. In addition protocols about changes in the entries by the observer can also provide information about the applicant, in particular if specific time values are associated with the respective changes, in the protocols. In particular if a test is assessed by a plurality of observers, comparison of the various automatic test protocols with linked time value recordal makes it possible to ascertain whether the change in a quality is to be attributed to a subjective erroneous assessment on the part of an observer or whether it is to be attributed to a change in the behavior of the applicant or the impression given by the applicant. When a number of observers is involved, the latter may result in an approximately simultaneous change in the entry, in relation to given qualities. Preferably the test results are recorded by a plurality of observers, the computers thereof being networked together. In addition the computers are preferably networked to a server. The server serves for central data storage. As mentioned above, while the test is being performed, a supervisor can view the data on the server and thus find out the assessments made by the observers at an early time. In that situation the test results are preferably written into a common database. In practice a result file can be automatically produced on the common database. That result file can either be displayed to the supervisor while the test is being performed or it can be used at the end of the test for the observer conference or for presentation of the test results. A further additional function which in the case of networking the computer can automatically execute for promoting implementation of the test is the communication function. In that respect, in practice at least one computer sends by way of a data network a message which is received and reproduced by at least one other computer. The observers can communicate with each other through that form of communication, without the test procedure being disturbed by that communication. For example short texts can be inputted into a text field and reproduced on a display field on the screen of the message recipient. The computer which receives and displays the messages does not necessarily have to be associated with an observer. It may also be associated with that person who is conducting an interview or performing a test without appearing as an observer. In particular in that case either the observers or a supervisor who also has a computer connected to the data network can communicate items of information and instructions to the person who is carrying out the test or conducting the interview. That happens without the applicant being able to notice the communication and feeling disturbed thereby. The message does not have to be transmitted in the form of a text message but can also be in any other forms and for example can be a spoken message. In that case, a microphone can be connected to the computer of a message sender, and a headset can be connected to the computer of the message recipient, by way of which headset the message transmitted by way of the data network is reproduced without the applicant hearing that. In practice the inputs into the computer are preferably inputted by way of a touch-sensitive screen, referred to as a touch screen. In particular a Tablet PC is suitable as the computer for the observer. This involves portable computers which have the usual hardware components of conventional notebooks (processor, working memory, hard disk drives, data interface, screen), in which the screen is a touch screen by way of which data inputs can be effected. Tablet PCs are known both in the form of so-called convertibles which can be converted from a conventional notebook by rotating the screen into a Tablet PC with the touch-sensitive screen surface facing upwardly. The casing portion with the keyboard then lies beneath the portion with the screen. A pure Tablet PC does not have a keyboard and only has the casing in which the screen and the other hardware components of the computer are disposed. The inputs can be effected in different ways on the touch-sensitive screen. For certain qualities, only a limited number of values (for example five different values) may be permissible. In that case an input window may be represented, listing the five values, on the screen of the computer, the selected value being marked and inputted by the observer. A text input can be effected by way of a keyboard. As typing on a conventional keyboard is generally loud and can interfere with the test, it is possible to produce the image of a keyboard on the touch-sensitive screen, with the individual letters being activated by tapping on the images of the respective letters. In a practical embodiment the inputs are effected in manuscript by way of a touch-sensitive screen. Modem Tablet PCs are equipped with powerful handwriting recognition programs. In the case of reproducible handwriting, the handwriting recognition program can convert the manuscript input into an alphanumeric text and store it as a text file. An image of the manuscript input can additionally or alternatively be stored as an image file. Combined storage of the two different files permits fast automatic further processing of the text file and checking of correct handwriting recognition with the assistance of the image file. A further advantage is that notes stored in the form of a text file can be immediately incorporated into an opinion which is produced on the basis of the test results. In another embodiment a speech recognition program may be executed on the computer to recognize spoken observations or evaluations of the observer. In practice the computer of an observer can produce a plurality of input masks for a plurality of persons who are observed simultaneously during a test. Each of the input masks can be activated by the observer by input with an input means, preferably by touching the touch screen at a given location with an input stylus. Each of the input masks preferably shows the name of a given person with whom it is associated, in an identification field. The corresponding input mask can be activated by touching that identification field. Additionally or alternatively it is possible for each of the input masks to display a picture of the person with whom it is associated. Displaying the picture of the person makes it possible to avoid an observer entering results relating to a person in the wrong input mask. For each input mask, the computer can automatically record the total time for which that input mask is activated by the observer during a test. In that way it is possible to establish how intensively an observer was occupied with a given person. The recorded amount of the total time for which the input mask of a given person was activated by the observer can be used to weight the inputs of that observer in relation to that given person. In practice moreover at least one video recording of implementation of the test can be made. In that way it is possible for observers who are remote from the location of the test to be integrated into implementation of the test. The video recording of the test can be transmitted by way of the Internet or by way of other transmission paths (television satellites and so forth) to a receiving person at any locations in the world, who watches the recording on a screen. That observer, like the observers on site, can enter the results in input fields of his computer. The fact of bringing the entered results together into a central result file by way of the Internet means that the results which are produced at a remote location can be taken into account precisely like the results produced on site. All results are available immediately after the termination of a test. Alternatively a video recording can be played back with a time shift and an observer can thus produce the results in time-shifted relationship. In that case, the results are available only when the last observer has produced the results, when viewing the video recording. However the video recording of a test also affords a further advantage in terms of test evaluation, evaluation of the observers and presentation of the test results. Upon test evaluation at an observer conference, an overall assessment can be produced not just on the basis of the times when entries were made, as recorded by the computer, and the recorded results. Those times and the results can also be associated with specific situations during the course of the test. At the same time that permits an assessment of the performance of the observers so that the method can also be used to advantage for assessing observation in the context of education or training. Finally, in regard to presentation of the test results before a personnel manager who was not personally present at the test, the video recording permits the test results to be clearly set forth by presentation of the actual test procedure by means of the video recording. In addition one embodiment of the invention concerns a computer program product which for recording the results of a psychological test can be loaded directly into the working memory of a computer and has program code portions which, when the program is executed, perform the steps of the above-described method. The computer program product produces on the one hand the input fields on the display of the computer and receives the entries of the observer and stores them in the data memory. In addition the computer program product contains the required program code portions for executing the automatic functions of result recordal and/or test implementation. One embodiment of the invention further covers a computer system for recording the results of a psychological test, in particular a test for personnel assessment, by at least one observer, which for each observer includes a computer on which a computer program product as mentioned runs. In practice said computer can include a timer, also referred to as a clock, for automatic time recordal. As mentioned the computer preferably has a touch-sensitive screen. Finally the computer should have a module for wireless data transmission. Networking of the computers of various observers with each other and optionally with a server can in practice be effected by a so-called wireless data network (WLAN=wireless local area network). Such a wireless data network permits data exchange between a wireless access point and a computer over 30 meters and more. The individual observers are therefore not restricted by the networked computer assigned to them in terms of their mobility. The architecture of the network can be of any nature. In practice the use of a local server which is connected to a wireless access point has proven useful for the network. In operation of larger assessment centers in which different tests are carried out in different rooms the local server can also be connected to a plurality of wireless access points by way of suitable networking so as to ensure reliable data transmission in all rooms of the assessment center. In practice the local server can be connected to a central server by way of a data network, in particular the Internet. That network architecture has a number of advantages. Professional personnel advisers of large corporations or independent corporations who are specialized in personnel consultation can store on their own server information and files which are required for performing various psychological tests. The fact that a mobile server always has access to the central server by way of a data network guarantees that all assessment centers which are operated by employees of that enterprise access the same up-to-date database. In addition the test results can be communicated from the mobile server to the central server almost in real time. That prevents data loss, for example due to damage to the mobile server, in particular if the central server has reliable data safeguard mechanisms, for example mirroring of a hard disk. The invention results in a considerable improvement in the level of reliability of assessment recording by human observers. This specification has already described hereinbefore how protocolling of the performance of the observer allows substantial conclusions to be drawn about the quality of evaluation of that observer. In addition the use of computers avoids the transfer of the entries of the respective observers into files which can be processed and stored on computers. That avoids transfer errors. In addition the costs for the work involved in data transfer are eliminated. Finally the data from all observers are available in a database immediately after the termination of the test. That is of crucial significance, in particular for an observer conference which is frequently carried out following a test. Besides the actual inputs from the observers, data analysis can be effected immediately after the test is concluded. For example, conformities on the part of the assessments of various observers can be ascertained. Very high or very low conformities can be automatically marked in a file or in a data display so that they attract attention and can be further discussed at an observer conference. In addition the evaluation methodology which is presently used can be improved. Hitherto assessments were furnished by the observers in each case once towards the end of the test. Computerized assessment recordal permits a plurality of entries at different times in relation to one assessment criterion so that possibly different impressions at the different moments in time can be protocolled and can be incorporated into the overall assessment. That counteracts the previously known effect where the result is falsified by the last impression. If an applicant makes a very good impression at the end of the test, there is the danger that the assessment turns out to be too good. Conversely, the risk of an excessively poor judgment arises in a situation involving a poor final impression. That result falsification effect can be counteracted by virtue of recording the assessment of individual criteria not just once at the end of the test but a plurality of times during the test. In a practical embodiment a mean value is formed from the results which are entered over the entire time of the test for a given criterion. Finally it is possible for the data recorded by the method described herein to be transferred into personnel databases, also referred to as human resource databases, which are usually managed by the personnel departments of relatively large corporations. While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the present invention as defined by the appended claims. FIG. 1 diagrammatically shows the arrangement of a computer system on which the method according to one embodiment of the invention for digitally recording personnel assessment can be carried out. The network for carrying out digital result recordal itself is shown in the right-hand part in FIG. 1. The network comprises a mobile server 1 which in the present case is shown in the form of a notebook computer. The mobile server 1 is configured to communicate in a wireless fashion with a wireless access point 2, also referred to as a hot spot. The wireless access point (WAP) is a network node for a wireless local area network (WLAN). Tablet PCs 3 can exchange data with the mobile server 1 and with each other by way of the wireless access point 2. The Tablet PCs 3 are for that purpose provided with a commercially available WLAN card, that is to say a wireless network access card, which communicates with the access point 2 by way of a common standard for wireless data networks, for example IEEE 802.11g Wireless Standard. In addition a Tablet PC 3 has a touch-sensitive screen 4, referred to also as a touch screen. The touch screen is generally a back-lit LCD flat screen with a touch-sensitive surface. It is however also possible to use other screen technologies which can be integrated in a light mobile device. Further operating elements 5 of the Tablet PC 3 are mounted to the frame surrounding the screen 4. The Tablet PC 3 has the usual devices of a mobile personal computer (processor=CPU, working memory=RAM, graphic card, hard disk drive, chargeable battery for power supply and so forth). By virtue of the fact that the Tablet PC 3 communicates with the server 1 by way of a radio network, it does not impede the observer using the Tablet PC 3, in terms of his freedom of movement. Each observer has his own Tablet PC 3 which communicates with the wireless access point (hot spot) 2 by way of the communication of its WLAN card and is thereby networked both with the server 1 and also with the other Tablet PCs 3 of other observers. The mobile server 1 itself is preferably connected by way of the Internet to a database 6 on a central server 7. The central server 7 can be associated for example with a personnel consultation enterprise or the personnel department of a large corporation. The database 6 of the central server 7 includes all data relevant for the various personnel tests of the corporation in question, in particular prepared input masks which are displayed on the Tablet PCs during recording of the test results and include input fields in which the observer can enter the results. Results of earlier tests can also be stored in the database of the central server 7. The central server 7 is connected by way of its own local area data network to a plurality of workstation computers 8. At the workstations 8 employees of the enterprise can call up, process and store the data on the central server 7. Finally FIG. 1 shows a video camera 10 connected to a video recording carrier 11 on which video recordings of the test are stored. Preferably digital video recordings are produced, which are stored with a time signal. In that way it is possible for the moment in time in the test to be associated with the moments in time of given entries, which are recorded by way of the Tablet PCs. The recording carrier 11 used can be for example a magnetic tape cassette or preferably a hard disk with a large storage capacity. The video recording also makes it possible for at least one observer to assess the tested person in time-shifted relationship, in this case also the test time being recorded automatically. Then the beginning of playback of the video recording is assumed to apply as the time of the test start so that the moments in time of the entries made can be associated with the moments in time of the entries actually made during the test by other observers. The time signal of the digital video recording also allows reproduction of the entries of the observers jointly with the playback of the video recording, with the times of the entries being associated with the times of the video recording. It is possible for example at the edge of a video image of the video recording to produce image segments which are associated with given observers and which display the entries thereof in an input mask while the test was being conducted. In that way it is possible not only to check the entries by reference to the video recordings, but it is also possible to check the performances of the observers and possibly improve them in the context of training. In the system shown in FIG. 1 the digital video recording is transmitted to the database 6 of the server 7 by way of the Internet. If required it can also be called up by way of the mobile server 1. With broadband access to the Internet the data of a digital video signal can be transmitted almost in real time. Only one video camera 10 is shown in FIG. 1. It will be appreciated that a plurality of video cameras 10 can be operated simultaneously and thus different perspectives of the test or different test rooms can be recorded. FIG. 2 shows networking of the individual computers of the system according to one embodiment of the invention for operation of an assessment center. The mobile server 1 is set up in a preparation room or conference room. It is preferably connected to the Internet by way of an Internet access so that it can access data in the central server 7 (see FIG. 1). A hot spot 2, also referred to as a wireless access point, is connected to the mobile server 1. Two further hot spots 2 in different rooms are connected to the hot spot 2 in the conference room by way of data lines 9. Any cable which is suitable for data transfer can be used as a data line 9. Conventional network cables are nowadays in the form of coaxial cables or twisted pair cables. It is however also possible to make a data connection by way of power lines of the power mains of a building. Finally it is also possible to set up radio connections between the various hot spots 2 of the network. Care is to be taken to ensure that all regions of the rooms of an assessment center in which observers are possibly present are covered by at least one of the hot spots 2 for implementing data transfer. The various hot spots 2 communicate with the WLAN cards in the Tablet PCs 3 on which a client program of the program running on the server 1 runs. The program running on the server 1 is referred in this application as the “digital assessment center”. FIG. 3 shows the various program modules which are used for carrying out personnel assessment according to one embodiment of the invention. It comprises on the one hand a database 100 which is stored on the mobile server 1 (see FIGS. 1 and 2). The database 100 can contain the same items of information as the database 6 (FIG. 1) on the central server 7 of the corporation. It may however also differ from that central database 6 as a connection to the central database is admittedly useful but is not absolutely required, for carrying out the method according to one embodiment of the invention. In this case, the data in the database 100 of the mobile server 1 is preferably co-ordinated from time to time with the data in the database 6 of the central server 7. The data recording program 200 which is identified as the “digital assessment center” runs on the mobile server 1 (FIGS. 1 and 2). An assessment client 301, 302, . . . , runs on each Tablet PC 3 of an observer, that is to say a program which controls result recording on the Tablet PC 3 (FIGS. 1 and 2) and forwards the recorded data to the “digital assessment center” 200 on the mobile server 1. The “digital assessment center” on the mobile server 1 takes over central control of the result recording programs 301, 302 . . . . It establishes in particular the beginning and the end of the test and, as mentioned, stores the various data which are communicated by the assessment clients 301, 302 . . . . Time recordal can be effected both centrally in the digital assessment center 200 and also decentrally in the individual assessment clients 301, 302 . . . . Decentral time recordal has the advantage that the assessment client 301, 302 . . . is operational even if a short-term interruption occurs in the wireless network connection to the mobile server 1. On the display device, namely the touch-sensitive screen of each Tablet PC 3, each assessment client 301, 302 produces the masks with the input fields required for result recording. FIGS. 4 and 5 show examples of such input masks. In this respect the input masks can be activated alternately by so-called flags or tabs at the upper edge of the image, if the procedure is to switch to and for between them. Each input mask is associated with a given person who is participating in the test. The name of the respective person is entered on the flag of the input mask. In addition the input mask can have a field in which a picture of the person is represented. That avoids results from the observers being associated with the wrong person. In FIGS. 4 and 5 the flag of the person F. Schmidt is activated in the left-hand column so that at the same time the picture of Mr. Schmidt is shown. The input mask in FIG. 4 permits the input of five different assessment stages which range from “far above average” to “far below average” and are associated with five different qualities of an applicant, which are to be evaluated by the observer. The evaluation stages associated with the various qualities can be activated by so-called control boxes arranged below the symbols associated with the evaluation stages. Such a procedure makes it possible to achieve comparable assessments by different observers. In accordance with one embodiment of the invention the Tablet PC 3 which is used as the computer for result recording records not only the evaluation stage selected for each quality but also the moment in time at which the evaluation stage was selected by the observer. In addition the assessment client 301, 302 . . . running on the Tablet PC 3 can also record changes in the evaluation stages in relation to given qualities and store the moments in time associated with the changes. It is possible in that way to arrive at conclusions in regard to changes in the impressions of the observers in the course of a given test. The program can also be designed in such a way that several results are admitted in relation to a given quality. In that case the evaluation stages which are determined at different moments in time can be entered by the observer in relation to that quality. In practice the mean value of all inputs in relation to a given quality is formed. That ensures that the impressions of a person on the observer are recorded and taken into consideration throughout the entire period of the test. Together with the inputted evaluation stages, the moments in time of the respective input can be recorded by the computer. Frequently the test results in the form of evaluation stages in relation to given qualities provide too little information about a given applicant. For that reason the assessment client 301, 302 . . . running on the Tablet PC 3, by virtue of the alternative input mask shown in FIG. 5, affords the possibility of manuscript input of notes. That input mask is activated by an observer by touching the function field shown at bottom left and identified by the name “NOTES” on the input mask in FIG. 4 with an input stylus. Equally, by touching the function field with the name “EVALUATION” in the input mask in FIG. 5, the observer can change back to the input mask of FIG. 4. The masks are switched over between the various persons being observed by touching the name flag at the upper edge of the input mask. The computer can automatically record when an observer has activated the input mask of each of the persons being observed. It is possible to conclude therefrom the total time for which an observer devoted himself to each of the persons being considered. The notes are entered by manuscript by way of the touch-sensitive screen 4 of the Tablet PC 3. A handwriting recognition program converts the manuscript entries into alphanumeric characters, preferably ASCII codes. The result of handwriting recognition is shown at the lower edge of the input mask illustrated in FIG. 5. As in many cases handwriting recognition does not yet operate without error, besides the ASCII codes of handwriting recognition digital image data of the manuscript notes can also be stored. That permits a later check of the notes recognized by handwriting recognition. The input mask shown in FIG. 5 can also be used for the manuscript input of a message. In that case it is to be coupled to further control fields which are to be represented on the screen 4 and which cause the message to be sent to a given computer or a group of computers in the network. Each computer which is connected to the network of the assessment center acquires a unique address and text messages can be sent for example in the manner of an e-mail message from one computer in the network to another. When the message is received the receiving computer produces on its screen a display window on which the message is displayed in such a way that it can be readily read by the observer. 1 mobile server 2 wireless access point 3 Tablet PC, computer 4 touch-sensitive screen, display device 5 operating elements 6 database 7 server 8 workstation 9 data line 10 video camera 11 recording carrierAlthough the system and method of the present invention have been described in connection with several embodiments, the invention is not intended to be limited to the specific forms set forth herein, but on the contrary, it is intended to cover such alternatives, modifications, and equivalents as may be reasonably included within the spirit and scope of the invention as defined by the appended claims.
	summary
	abstract	A fuel assembly for a nuclear power boiling water reactor including a fuel channel defining a central fuel channel axis, fuel rods, each having a central fuel rod axis, at least 3 water channels for non-boiling water, each water channel having a central water channel axis and each water channel having a larger cross-sectional area than the cross-sectional area of (the average) fuel rod. The fuel rods include a first group of full length fuel rods and a second group of shorter fuel rods. The fuel assembly comprises 3 or 4 fuel rods which belong to said second group and which are positioned such that the central fuel rod axis of each of these 3 or 4 fuel rods is closer to the central fuel channel axis than any of the water channel axes of the water channels.
048658030	summary	BACKGROUND OF THE INVENTION The present invention relates to a pressurized gas discharge system for the safety containment of a nuclear reactor which includes a conduit having a filter arrangement with serially arranged filter elements consisting of stainless steel fiber packs. It is assumed that, after a reactor melt-down accident, the gas pressure within the safety containment of a nuclear reactor will increase within a couple of days to a degree that gas should be discharged therefrom. There are provided therefore discharge apparatus for limiting or reducing the pressure by way of a duct which provides communication of the containment interior and the atmosphere, that is, a discharge stack via a filtering system. The present invention relates to such a filtering system. The filtering systems utilized so far are not capable of safely handling the discharge of the gases under the given conditions involving a combination of water, steam, high temperatures and radiation. It is therefore the object of the present invention to provide a gas discharge system for the safety containment of a nuclear reactor which, with the use of stainless steel filter element packs, will permit to limit the containment pressure over a longer period of time and which remains functional over the whole period. Such a system needs to be resistant to high temperatures and corrosion, require little servicing and be highly reliable. SUMMARY OF THE INVENTION In a pressurized gas discharge system for the safety containment of a nuclear reactor which includes a conduit structure connected to the safety containment for receiving the gases to be discharged from the interior thereof and which consists of a plurality of modular conduit units flanged together end-to-end and provided with side openings with circumferential flanges, a plurality of frame members are flanged to the sides of the modular conduit units in end-to-end relationship and in alignment with the side openings of the modular conduit units and filter packs of stainless steel fibers are clamped with their circumferential edges between the flanges of adjacent frame members such that the filter packs extend fully across the frame members, one of the flanges of adjacent frame members having a U-shaped member disposed on its face such that the legs thereof project toward the flange of the adjacent frame member and firmly engage the circumferential edges of the filter packs which are compressed thereby to a fraction of their original thickness and form with the legs of the U-shaped member a double seal strip between the frame member flanges. The system according to the present invention provides for a substantial improvement in nuclear plant safety and reduces the remaining risks without the need for additional emergency measures. The system according to the invention additionally provides for long-term effectiveness and reliable operation even under the described extreme conditions as they would occur during a melt-down accident.
	summary
	description	The present application claims priority from Japanese Patent Application No. 2008-154012 filed on Jun. 12, 2008, the contents of which are incorporated herein by reference in their entirety. 1. Field of the Invention The present invention relates to an extreme ultraviolet (EUV) light source apparatus for generating extreme ultraviolet light by applying a laser beam to a target material to turn the target material into plasma, and specifically, to an EUV light source apparatus for supplying high-quality extreme ultraviolet light with spectrum purity improved by eliminating the influence of the laser beam applied to the target material. 2. Description of a Related Art Recent years, as semiconductor processes become finer, photolithography has been making rapid progress to finer fabrication. In the next generation, microfabrication at 70 nm through 45 nm, further, microfabrication at 32 nm and beyond will be required. Accordingly, in order to fulfill the requirement for microfabrication at 32 nm and beyond, for example, exposure equipment is expected to be developed by combining an EUV light source generating EUV light having a wavelength of about 13 nm and reduced projection reflective optics. As the EUV light source, there is an LPP (laser produced plasma) light source using plasma generated by applying a laser beam to a target (hereinafter, also referred to as “LPP type EUV light source apparatus”). In the LPP type EUV light source apparatus, a target material is injected from a nozzle and a laser beam is applied toward the target material, and thereby, the target material is excited and turned into plasma. Various wavelength components including extreme ultraviolet (EUV) light are radiated from the plasma. Accordingly, a desired EUV light is selected using a collector mirror (EUV collector mirror) for selectively reflecting and collecting a desired wavelength, and the desired EUV light is output to external equipment such as an exposure unit. For example, when EUV light having a wavelength near 13.5 nm is collected, an EUV collector mirror having a reflecting surface is used on which a multilayer film with alternately stacked molybdenum and silicon (Mo/Si multilayer film) is formed. However, also the light directly radiated from the target plasma and excitation laser beam reflected from the target and so on are mixed in the desired EUV light. A resist for exposure to be used in the EUV exposure unit is exposed to light having a wavelength from 130 nm to 400 nm in the spectrum of light generated from the target plasma, and it may reduce the exposure contrast. Further, infrared light contained in the excitation laser beam may be absorbed by optical parts, masks, wafers, and so on, to cause thermal expansion, and it may reduce the accuracy of patterning. Therefore, it is necessary to suppress those light components. Conventionally, in the LPP type EUV light source apparatus, a spectrum purity filter (SPF) has been used for removing components unnecessary for EUV exposure from the spectrum of light radiated from plasma. In a technology disclosed in U.S. Pat. No. 6,809,327 B2, as shown in FIG. 17, a laser beam emitted from a carbon dioxide (CO2) laser is introduced into a vacuum chamber and focused, the laser beam is applied to a target of tin (Sn) droplets or the like supplied by a target supply unit to turn the target into plasma, light radiated from the plasma is collected by an EUV collector mirror, and the collected light is spectrum-separated by a grating type SPF, and thereby, only the EUV light having a wavelength around 13.5 nm (negative first-order light in the drawing) is guided to an exposure unit. Further, by providing a thin film filter between the exposure unit and the vacuum chamber, Sn debris flying from the target material (Sn) introduced into the vacuum chamber and the target plasma is prevented from flowing to the exposure unit side and contaminating optical parts within the exposure unit. When a material such as zirconium (Zr) or silicon (Si) with higher transmittance for EUV light having a wavelength around 13.5 nm than for other wavelengths is selected, the thin film filter also serves as a thin film filter type SPF. In the conventional LPP type EUV light source apparatus as shown in FIG. 17, the light spectrum-separated and eliminated by the grating type SPF is absorbed by a dumper and turns into thermal energy. Further, Japanese Patent Application Publication JP-P2006-191090A discloses another SPF using apertures or an aperture array for reflecting light having a longer wavelength than twice the width of the aperture to suppress transmission of the light. Furthermore, Japanese Patent Application Publication JP-P2007-129209A discloses using, as an SPF, a gas curtain formed by combining necessary kinds of gases that do not have absorption capability for EUV light but have absorption capability for wavelengths to be eliminated. Especially, in the LPP type EUV light source apparatus using a CO2 laser beam (infrared light having a wavelength of 10.6 μm) for excitation of the Sn target, the CO2 laser beam having high-power is also reflected or scattered by the target or the like, and it is necessary to remove the CO2 laser beam by the SPF. For example, assuming that the intensity of the EUV light with the center wavelength of 13.5 nm is “1”, the intensity of the CO2 laser beam is required to be suppressed to about “0.1” or less. Accordingly, in view of removal of the CO2 laser beam, there have been the following problems in the above-mentioned conventional technologies. (1) Since the transmittance of the thin film filter type SPF that isolates the exposure unit from the EUV light source apparatus is as low as about 40%, the output efficiency of EUV light is very poor. Further, the thin film is easily broken by the incidence of debris. Furthermore, when debris adheres to the thin film, the debris absorbs EUV light and the temperature rises, and the filter itself may be melted, and therefore, it is difficult to maintain the function as the SPF.(2) In the SPF using an aperture array, there are issues of improving the efficiency of EUV light to be outputted to the exposure unit by improving the aperture ratio while maintaining the structural strength of the SPF, improving the reflectance of the CO2 laser beam to be blocked, and reducing the risk of deformation and breakage due to temperature rise caused by light absorption. Further, the fine intensity distribution of EUV light generated in the aperture array may disturb the exposure uniformity of the semiconductor and cause exposure variations.(3) In the SPF utilizing the selective absorption of gases, no kinds of gases suitable for absorption of CO2 laser beam is disclosed. The present invention has been achieved in view of the above-mentioned problems. The purpose of the present invention is to provide an EUV light source apparatus using a spectrum purity filter (SPF) capable of obtaining EUV light with high spectrum purity. In order to accomplish the above-mentioned purpose, an extreme ultraviolet light source apparatus according to one aspect of the present invention is a laser produced plasma type extreme ultraviolet light source apparatus for generating extreme ultraviolet light by applying a laser beam to a target material, and the apparatus includes: a chamber in which extreme ultraviolet light is generated; target supply means for supplying a target material to a predetermined position within the chamber; a driver laser using a laser gas containing a carbon dioxide gas as a laser medium, for applying a laser beam to the target material supplied by the target supply means to generate plasma; a collector mirror for collecting the extreme ultraviolet light radiated from the plasma to output the extreme ultraviolet light; and a spectrum purity filter provided in an optical path of the extreme ultraviolet light outputted from the collector mirror, for transmitting the extreme ultraviolet light and reflecting the laser beam, the spectrum purity filter including a mesh having electrical conductivity and formed with an arrangement of apertures having a pitch not larger than a half of a shortest wavelength of the laser beam applied by the driver laser. The mesh may be formed of a material having electrical conductivity, or may be formed by coating a material having electrical conductivity on at least a light incident surface or a back or a sidewall thereof. According to the one aspect of the present invention, by using the spectrum purity filter (SPF) including the mesh formed with an arrangement of apertures having a pitch not larger than a half of a shortest wavelength of the laser beam applied by the driver laser, the EUV light having a short wavelength is transmitted and the CO2 laser beam having a long wavelength is reflected, and thereby, EUV light having high spectrum purity can be obtained. Further, in the case of providing a metal coating of gold, molybdenum, or the like to the light incident surface of the mesh, the CO2 laser beam becomes hard to be absorbed by the light incident surface of the mesh of the SPF, and the risk of deformation and breakage caused by temperature rise of the SPF is reduced. Since an oscillation wavelength of a general CO2 gas laser is 10.6 μm, an SPF formed with an arrangement of apertures having a pitch not larger than a half of a wavelength of the laser beam, that is, a pitch not larger than 5.3 μm may be used. Further, in the case where a CO2 gas laser oscillates in a band of transition 00°1-02°0, an oscillation wavelength of the CO2 gas laser becomes nearly 9.56 μm. In this case, an SPF formed with an arrangement of apertures having a pitch not larger than a half of a wavelength of the laser beam, that is, a pitch not larger than 4.78 μm may be used. As mentioned above, in order to reflect the CO2 laser beam, an SPF formed with an arrangement of apertures having a pitch not larger than a half of a shortest wavelength of the laser beam applied by the driver laser is necessary. Hereinafter, preferred embodiments of the present invention will be explained in detail by referring to the drawings. The same reference numerals are assigned to the same component elements and the description thereof will be omitted. (First Embodiment) FIG. 1 shows a configuration of an extreme ultraviolet (EUV) light source apparatus according to the first embodiment of the present invention. The EUV light source apparatus employs a laser produced plasma (LPP) type of generating EUV light by applying a laser beam to a target material for excitation. As shown in FIG. 1, the EUV light source apparatus according to the embodiment includes a first vacuum chamber 1 in which EUV light is generated and a second vacuum chamber 2 for guiding the generated EUV light to an external exposure unit, and improves the quality of the generated EUV light 10 with a mesh-type spectrum purity filter (SPF) 22. Further, the EUV light source apparatus includes a target supply unit 5 for supplying a target 4 to a predetermined position (beam focusing point 9) within the first vacuum chamber 1, a driver laser 6 provided outside of the first vacuum chamber 1, a laser beam focusing optics 8 including at least one lens and/or at least one mirror arranged outside and/or inside of the first vacuum chamber 1, for guiding and focusing an excitation laser beam 7 applied by the driver laser 6, an incident window 34 for introducing the excitation laser beam 7 into the first vacuum chamber 1, an EUV collector mirror 11 for reflecting and collecting the EUV light 10 radiated from plasma generated when the excitation laser beam 7 is applied to the target 4 at the beam focusing point 9, a first vacuum pump 12 for evacuating the first vacuum chamber 1, and a second vacuum pump 25 for evacuating the second vacuum chamber 2. Furthermore, the EUV light source apparatus includes a first pinhole aperture (aperture part) 14 provided on a partition wall between the first vacuum chamber 1 and the second vacuum chamber 2, for connecting the first vacuum chamber 1 to the second vacuum chamber 2, and a second pinhole aperture (aperture part) 23 for guiding EUV light entering from the first pinhole aperture 14 to an exposure unit. Furthermore, the EUV light source apparatus may include a mitigation unit 16 for protecting the EUV collector mirror 11 and so on from debris. The mitigation unit 16 may include a superconducting coil electromagnet 19 for generating lines of magnetic force 20 surrounding the plasma, for example. Moreover, the EUV light source apparatus may include a valve for introducing an etchant gas for cleaning, and a gate valve 28 provided at the downstream of the second pinhole aperture 23, for preventing the etchant gas from flowing out into the exposure unit at cleaning. The target supply unit 5 heats and dissolves solid tin (Sn) and supplies it in a solid state or liquid droplets as the target 4 into the first vacuum chamber 1. The target 4 passes through the beam focusing point 9 at which it intersects with the excitation laser beam 7. The driver laser 6 is a high-power CO2 pulse laser using a laser gas containing a carbon dioxide gas (CO2) as a laser medium (e.g., the output: 20 kW, the pulse repetition frequency: 100 kHz, the pulse width: 20 ns). The excitation laser beam (CO2 laser beam) 7 applied by the driver laser 6 is focused on the target 4 via the laser beam focusing optics 8 and the incident window 34 of the first vacuum chamber 1, excites the target 4 to turn it into plasma, and generates EUV light 10 (the center wavelength: 13.5 nm). The generated EUV light 10 is collected and outputted to an intermediate focus (IF) by the EUV collector mirror 11 having an ellipsoidal reflecting surface, and guided to the exposure unit. When the target 4 is excited, the CO2 laser beam 7 applied by the driver laser 6 is reflected by the target 4 and scattered or reflected by the plasma generated at the beam focusing point 9, and reflected and collected by the EUV collector mirror 11 toward the IF. The SPF 22 for blocking the CO2 laser beam 7 is arranged between the IF and the EUV collector mirror 11, and transmits the EUV Light 10 having the center wavelength of 13.5 nm necessary for EUV exposure from among the light reflected by the EUV collector mirror 11. On the other hand, the SPF 22 reflects the CO2 laser beam 7 and the reflected CO2 laser beam 7 enters a water-cooling dumper 24 arranged on a reflection optical axis of the EUV collector mirror 11, and is absorbed and converted into heat. Alternatively, the SPF 22 may be slightly tilted such that light having a long wavelength such as a CO2 laser beam is reflected in a direction at an angle relative to the reflection optical axis of the EUV collector mirror 11, and the water-cooling dumper 24 may be arranged in a position not to block the EUV light 10 reflected by the EUV collector mirror 11. The two pinhole apertures 14 and 23 are arranged at the upstream and downstream of the IF, and the degree of vacuum is made higher in the second vacuum chamber 2 between the two pinhole apertures 14 and 23 by the vacuum pump than that in the first vacuum chamber and in the space connecting to the exposure unit. The diameters of the apertures 14 and 23 are about several millimeters. The IF is provided in the second vacuum chamber 2 other than the first vacuum chamber 1. By this configuration, the target and debris within the first vacuum chamber 1 are prevented from flowing into the exposure unit according to the principle of differential evacuation. In the embodiment, the superconducting coil electromagnet 19 for generating a magnetic field is used as the mitigation unit 16 for protecting the optical elements (the SPF 22, the EUV collector mirror 11, the laser beam focusing optics 8, the incident window 34, incident windows of an EUV light sensor and other optical sensors, and so on) within the first vacuum chamber 1 from the debris flying from the plasma at the beam focusing point 9. Since Sn ions generated from the target plasma have charge, the ions are subjected to Lorentz force in the magnetic field, restrained by the lines of magnetic force, and ejected to the outside of the first vacuum chamber 1 by the vacuum pump 12. On the other hand, neutral Sn particles other than the ions generated from the target plasma are not restrained by the magnetic field, and fly to the outside of the lines of magnetic force as Sn debris and gradually contaminate the optical elements. In the embodiment, the probability that the debris passes through the pinhole aperture 14 is lowered by imposing a spatial restriction by the pinhole aperture 14, and the debris that has passed the pinhole aperture 14 is collected by a vacuum pump 25. Thus, the debris hardly flows into the exposure unit through the other pinhole aperture 23. However, due to diffusion of neutral debris within the first vacuum chamber 1, the surface of the SPF 22 may be gradually contaminated by the debris and overheated. In this case, the SPF 22 may be cleaned by using the etchant gas under the condition that the operation of the EUV light source apparatus is temporarily stopped and the exposure unit is completely isolated from the first vacuum chamber 1 and the second vacuum chamber 2 by closing a gate valve 28 provided near the IF. As the etchant gas, a hydrogen gas, halogen gas, hydrogen halide, argon gas, or mixed gas of them is used, and the cleaning may be promoted by heating the SPF 22 with a heating unit (not shown). Further, the cleaning may be promoted by exciting the etchant gas with RF (radio frequency) waves or microwaves. When the cleaning is finished, the supply of the etchant gas is stopped. After confirming that the degree of vacuum in the second vacuum chamber 2 is made lower enough by the vacuum pump 25, the gate valve 28 is opened and the operation of the EUV light source apparatus is restarted. By the above-mentioned mitigation unit 16 using the magnetic field, the surface of the SPF 22 can be effectively prevented from being sputtered by the Sn ions. However, the neutral Sn debris is deposited on the SPF 22, and thereby, the reflectance of the CO2 laser beam in the SPF 22 is gradually reduced with the operation, and the SPF 22 absorbs light and the temperature rises. In the embodiment, by observation of the temperature distribution of the SPF 22 with a thermoviewer, and when sensing that the temperature rise is greater than a threshold level due to adherence of the neutral Sn debris, the apparatus may be stopped for replacement or the above-mentioned cleaning of the SPF 22. FIG. 2 is a perspective view showing a first example of the SPF used in the extreme ultraviolet light source apparatus according to the first embodiment. The SPF includes a mesh 22a in which an arrangement of apertures having a predetermined pitch is formed. In the first example, the mesh 22a has a square-lattice form. The mesh 22a may be manufactured by arranging plural wires laterally and longitudinally, or manufactured by forming plural apertures on a substrate to remain frames, for example. Here, assuming that each wire or frame has a diameter D and each aperture has a lateral width Wx and a vertical width Wy, each of the lateral pitch (Wx+D) and the vertical pitch (Wy+D) is made equal to or less than a half of a wavelength of an incident electromagnetic wave, that is, a CO2 laser beam in the embodiment. For example, by making each of the lateral pitch and the vertical pitch equal to or less than 5 μm, the CO2 laser beam having a wavelength of 10.6 μm is blocked, and transmittance becomes about 1/1000, and thus, the CO2 laser beam is prevented from passing therethough. On the other hand, the EUV light having a center wavelength of 13.5 nm is transmitted through the SPF 22 according to the aperture ratio of the mesh. The aperture ratio E (%) is calculated by the following equation.E=100×(Wx×Wy)/((Wx+D)×(Wy+D)) For example, given that each of the lateral width Wx and the vertical width Wy of the aperture is 4.5 μm and the diameter D of the wire or frame is 0.5 μm, the aperture ratio E is 81%. In practice, the mesh acts on the EUV light as a diffraction grating, and the transmittance is further reduced in consideration of diffraction loss. FIGS. 3 and 4 are diagrams for explanation of relationships between the aperture of the mesh shown in FIG. 2 and the transmittance of the EUV light. FIG. 3 shows changes of diffraction loss and transmittance relative to the aperture ratio of the mesh, and FIG. 4 is a diagram for explanation of the diffracted light generated on the surface of the SPF. When the first or higher order of diffracted light as shown in FIG. 4 is calculated as loss, there is a relationship between the aperture ratio and the transmittance as shown in FIG. 3. FIG. 3 also shows the transmittance without diffraction loss. In consideration of diffraction loss in the mesh having an aperture ratio of 81%, the transmittance is about 66%. Further, from FIG. 3, it is known that the mesh having a high aperture ratio, for example, equal to or larger than 80% is desirable for reducing the diffraction loss. Referring to FIG. 1 again, in order to minimize the loss of the EUV light toward the exposure unit, it is required that the position of the SPF 22 is made closer to the position of the IF such that the diffracted light is also used in the exposure unit. When the position of the SPF 22 is made closer to the IF, energy density of the EUV light entering the SPF 22 becomes greater, and it is required that no structural deformation or breakage occurs even when the SPF 22 absorbs light having great energy density and its temperature rises. FIG. 5 is a plan view showing a second example of the SPF used in the extreme ultraviolet light source apparatus according to the first embodiment. Further, FIG. 6 is a sectional view along A-A in FIG. 5. The SPF includes a mesh 22b in which an arrangement of apertures having a predetermined pitch is formed. In the second example, the mesh 22b has a honeycomb form. The mesh 22b may be manufactured by consecutively arranging plural frames each having a regular hexagon shape, or forming plural apertures on a substrate, for example. In the second example, an arrangement of apertures has a pitch (W+D) at maximum, and the pitch is made equal to or less than 5 μm. The SPF shown in FIG. 5 includes the honeycomb mesh 22b more adapted to the above-mentioned requirements, and realizes a high aperture ratio and high EUV light transmittance while maintaining the mechanical strength of the mesh. There are advantages that the honeycomb structure is a strong and hardly deformed structure obtained by arranging regular hexagons without gaps, an amount of a material necessary for manufacture can be made small, the diameter D of the frames forming the hexagons can be made small, and the aperture ration can be taken larger, and so on. In the embodiment, the material of the mesh is a material having a high coefficient of thermal conductivity and high rigidity such as silicon (Si), silicon carbide (SiC), diamond-like carbon (DLC), diamond, or the like, and maintains the mechanical strength of the SPF. A metal coating of gold (Au), molybdenum (Mo), or the like is provided to at least the light incident surface of the mesh, improves the reflectance of the CO2 laser beam, reduces the absorption of the CO2 laser beam in the SPF, and reduces the thermal deformation and breakage of the SPF. Further, since the mesh is manufactured by using a material having a high coefficient of thermal conductivity, the heat can be efficiently removed via a holder for holding the periphery of the mesh, and the thermal deformation and breakage of the SPF can be further reduced. FIG. 7 is a sectional view showing a third example of the SPF used in the extreme ultraviolet light source apparatus according to the first embodiment. In the SPF, a substrate made of the same material as that of the mesh is arranged on a light exit surface of the mesh. In order to fabricate such a structure, for example, a silicon (Si) substrate is etched by using an etching device to be used in the semiconductor manufacturing process, and thereby, the substrate and the mesh are integrally fabricated. A metal coating of gold (Au), molybdenum (Mo), or the like is applied on at least the light incident surface of the mesh, and thereby, improves the reflectance of the CO2 laser beam, reduces the absorption of the CO2 laser beam in the SPF, and reduces the thermal deformation and breakage of the SPF. Although examples are shown in FIGS. 6 and 7, in which a metal coating of gold (Au), molybdenum (Mo), or the like is provided on the light incident surface of the mesh so as to efficiently reflect the CO2 laser beam, the present invention is not limited to these examples. As far as the mesh has electrical conductivity, it is possible to reflect an electromagnetic wave or light having a wavelength equal to or larger than twice a pitch of the mesh. Specifically, the mesh itself may be formed of a material having electrical conductivity, or a material having electrical conductivity may be coated on the light incident surface, a back, or a sidewall of the mesh. Further, the thickness of the silicon substrate is made as thin as about 150 nm and the rear surface of the silicon substrate is coated with zirconium (Zr), and thereby, the substrate part also has the optical characteristic of the conventional thin film filter type SPF and can suppress transmission of not only the CO2 laser beam but also other unwanted spectra. Furthermore, the mesh reinforces the substrate in strength, and has greater mechanical strength than the conventional thin film filter type SPF, and hard to be broken. As the material of the substrate and the mesh, a material having high transmittance for EUV light and great mechanical strength such as silicon carbide (SiC), diamond-like carbon (DLC), diamond, or the like may be employed as well as silicon. When the material of the substrate and the mesh has high hardness and a high coefficient of thermal conductivity like diamond or the like, the substrate and mesh can be made thinner while the mechanical strength is held, and thereby, the aperture ratio is greater and the transmittance for EUV light is higher, and the efficiency of the light source can be improved. Furthermore, since the coefficient of thermal conductivity is great, the light energy absorbed by the substrate and the mesh can be efficiently removed and the risk of the deformation and breakage can be reduced. FIG. 8 is a perspective view showing an SPF including a holder. In FIG. 8, the case of using the mesh 22a is shown, however, the mesh 22b may be also used. The mesh 22a of the SPF 22 is thin and flexible, and therefore, unable to autonomously hold its position. Accordingly, by holding the periphery of the mesh 22a with the holder 31 such that the surface of the mesh 22a is flat, adequate surface tension is obtained, and the mesh 22a is provided within the first vacuum chamber 1 as a film-like element under tension. The holder 31 of the SPF 22 is made of a metal having a high coefficient of thermal conductivity such as copper, and has a structure in which a channel for passing a medium (water or the like) for cooling or heating the mesh is formed. FIG. 8 shows an inlet 31a and an outlet 31c of the channel. Since the mesh 22a of the SPF 22 is formed of a material having a high coefficient of thermal conductivity, the heat generated in the mesh 22a can be efficiently removed via the holder 31 for holding the periphery of the mesh 22a. Therefore, by using the holder 31, the thermal deformation and breakage of the SPF 22 can be prevented. Further, when the SPF 22 is cleaned with an etchant gas or the like, the mesh 22a may be heated via the holder 31 for promotion of chemical reaction for cleaning. FIGS. 9 and 10 are conceptual diagrams for explanation of a mechanism of rotating or vibrating the holder of the SPF. FIG. 9 shows a mechanism for rotating the holder 31 with a motor or the like. By rotating the SPF 22, the variations in the part of the SPF 22, to which EUV light is applied, are averaged, and the fine intensity distribution of transmitted EUV light caused by transmittance variations of the SPF 22 is solved by time integration, and thereby, exposure variations can be improved. The holder 31 may be rotated by an ultrasonic motor as disclosed in Japanese Patent Application Publication JP-A-7-184382, which is incorporated herein by reference. According to the technique of rotating the SPF, the location, where the CO2 laser beam reflected or diffused by the targetis applied, changes with the rotation, and thereby, the heat generated in the SPF 22 can be efficiently diffused and the life of the SPF 22 can be extended. Further, FIG. 10 shows a direct-driving actuator including a piezoelectric element or the like. By providing vibration to the SPF 22, the fine intensity distribution of transmitted EUV light generated by the SPF 22 is solved by time integration, and thereby, exposure variations can be improved. (Second Embodiment) FIG. 11 shows a configuration of an extreme ultraviolet light source apparatus according to the second embodiment of the present invention. In the second embodiment, a driver laser 32 uses a laser gas containing a carbon dioxide (CO2) gas as a laser medium and radiates an excitation laser beam (CO2 laser beam) having linear polarization, and a wire grid polarizer is used in place of the mesh in a spectrum purity filter (SPF) 33. The rest of the configuration is the same as that in the first embodiment. FIG. 12 is a principle diagram for explanation of the polarization direction of the CO2 laser beam and the wire grid polarizer. The wire grid polarizer 41 has periodically arranged wires of a metal or the like, and the wire spacing is made equal to or less than a half of a wavelength of an incident electromagnetic waves, that is, the CO2 laser beam in the embodiment. As shown in FIG. 12, the wire grid polarizer 41 has transmittance that changes according to the polarization direction of the incident electromagnetic waves. In the case where the pitch of the wires is equal to or less than 5 μm, the wire grid polarizer 41 reflects and blocks the CO2 laser beam at high reflectance when the electric field vibration direction in the CO2 laser beam having the linear polarization and the extending direction of the wires are substantially the same. Accordingly, in FIG. 11, by determining the polarization direction of the excitation laser beam 7 applied by the driver laser 32 and the direction of the wire grid in the SPF 33 as described above, the SPF 33 can reflect the CO2 laser beam reflected by the target and suppress the CO2 laser beam from entering the exposure unit. On the other hand, the EUV light has transmittance and diffraction loss according to the aperture ratio similarly to the mesh in the first embodiment. The difference from the mesh is that the wires are only in one direction in the wire grid polarizer. The substantial aperture ratio E (%) is expressed by the following equation.E=100×W/(W+D)Therefore, when the diameter D and the aperture width W of the wires are made the same as those in the mesh type, the higher aperture ratio, i.e., the higher EUV transmittance than that of the mesh type can be expected. The light component of the reflected CO2 laser beam and so on enters the dumper 24 and is absorbed. In FIG. 11, the dumper 24 is arranged off the optical axis, however, it may be arranged on the optical axis as shown in FIG. 1. When it is difficult to obtain the linear polarized CO2 laser beam, by arranging two wire grid polarizers overlapping such that the extending directions of the respective wires are orthogonal to each other, the CO2 laser beam can be blocked as is the case of the mesh. The CO2 laser beam becomes linear polarized light having a polarization plane in a direction orthogonal to the direction of the extending direction of the wires after transmitted through the first wire grid polarizer, and thus, the CO2 laser beam is unable to pass through the second wire grid polarizer provided orthogonally to the first wire grid polarizer. In this way, the CO2 laser beam applied by the driver laser 6 can be efficiently blocked regardless of its polarization state. In this case, the difference from the case of one wire grid polarizer is that the heat load per one polarizer due to light absorption is reduced to half and thermal deformation and breakage becomes less because the light is reflected and absorbed by the two wire grid polarizers. These wire grid polarizers are fabricated of a material having a high coefficient of thermal conductivity and high rigidity such as silicon (Si), silicon carbide (SiC), diamond-like carbon (DLC), diamond, or the like similarly to the mesh in the first embodiment such that the mechanical strength of the SPF 33 is maintained. Further, a metal coating of gold (Au), molybdenum (Mo), or the like is provided to at least the light incident surface of the wire grid polarizer such that the reflectance of the CO2 laser beam is improved, the absorption of the CO2 laser beam by the SPF 33 is reduced, and the thermal deformation and breakage of the SPF 33 are reduced. Further, since the wires of the wire grid polarizer are made of a material having a high coefficient of thermal conductivity, as is the case of the SPF 22 in the first embodiment as shown in FIG. 8, by providing the holder 31 (FIG. 8) for holding the periphery of the wire grid polarizer such that the surface of the wire grid polarizer is flat, the heat can be efficiently removed via the holder, and the thermal deformation and breakage of the SPF 33 can be further reduced. In the first and second embodiments, the SPF 22 or SPF 33 is provided between the EUV collector mirror 11 and the IF, however, the same effect can be obtained even when the SPF is provided in an arbitrary location in an optical path of the EUV light 10 such as a space of the exposure unit side at the downstream of the IF in the passage of the EUV light 10. (Third Embodiment) FIG. 13 shows a configuration of an extreme ultraviolet light source apparatus according to the third embodiment of the present invention. In the embodiment, an SPF of gas absorption type specialized for blocking the CO2 laser beam is used and sulfur hexafluoride (SF6) gas is used as a gas for absorption. The rest of the configuration is the same as that in the first embodiment. In the embodiment, a gas introducing nozzle 43 and a gas discharging nozzle 47 are provided to face each other near the IF within the first vacuum chamber 1. The SF6 gas is introduced near the IF within the first vacuum chamber 1 via the gas introducing nozzle 43 and the SF6 gas is collected into the gas discharging nozzle 47 by using a vacuum evacuation pump, and thereby, a gas curtain 45 of SF6 is generated. The sulfur hexafluoride (SF6) gas has a property of specifically absorbing the CO2 laser beam having a wavelength of 10.6 μm, and absorbs and blocks the CO2 laser beam of the light focused toward the IF. The technology of the gas curtain is disclosed in JP-P2007-129209A. However, nothing about the use of SF6 gas in the apparatus using the CO2 laser beam is described. The SF6 gas has nonlinear absorption rate for the CO2 laser beam, and the absorption rate is high when the light energy density intensity is low and the absorption rate becomes lower as the light energy density intensity becomes higher. When the SF6 gas is used as the SPF of gas absorption type, absorption is less in the focused part of the CO2 laser beam in which the energy density intensity is very high for excitation of the plasma for generating the EUV light, however, it is possible to effectively absorb the CO2 laser beam reflected or scattered by the target or the like and having low energy density intensity. Therefore, the CO2 laser beam reflected or scattered by the target or the like can be efficiently absorbed and blocked while the energy for excitation of the plasma for generating the EUV light is maintained. Further, the region, where the CO2 laser beam for excitation of the plasma for generating the EUV light is focused, is partially covered by a hood 49 and the space within the hood is purged with argon (Ar) gas introduced from a purge nozzle 51, and thereby, the concentration of the SF6 gas in the region, where the CO2 laser beam is focused, is reduced, and the absorption of the CO2 laser beam can be further reduced. Although argon (Ar) gas is used as a purge gas in this example, the present invention is not limited to this example, and a buffer gas such as hydrogen (H2) gas or helium (He) gas can be used as the purge gas. The above-mentioned SF6 gas and Ar gas are ejected by three vacuum evacuation pumps. Here, it is necessary to maintain the concentration of the gas within the first vacuum chamber 1 equal to or less than 1 Torr, for example, such that the gas within the first vacuum chamber 1 can sufficiently transmit the EUV light. In the third embodiment, as is the cases of the first and second embodiments, the two pinhole apertures 14 and 23 are arranged at the upstream and downstream of the IF and the space between the apertures is used as the second vacuum chamber 2, and the respective parts are formed such that the IF is located within the second vacuum chamber 2. The degree of vacuum is made higher in the second vacuum chamber 2 by the vacuum pump 25, and thereby, the debris generated in the first vacuum chamber 1 and the SF6 gas can be ejected from the second vacuum chamber 2 and prevented from entering the exposure unit. In the fourth embodiment, a CO2 laser system for performing multiline amplification is used as the driver laser of the EUV light source apparatus. Other configuration is the same as that in the first to third embodiments. FIGS. 14A and 14B show amplitude lines of a CO2 laser. In each of a band of transition 00°1-10°0 as shown in FIG. 14A and a band of transition 00°1-02°0 as shown in FIG. 14B, there exist plural amplification lines (see C. K. N. Patel, “Continuous-Wave Laser Action on Vibrational Transition of CO2”, American Physical Society, Vol. 135(5A), A1187-A1193, November 1964). A general CO2 gas laser performs laser oscillation at only an amplification line P (20) with a wavelength of 10.6 μm. The reason is that a gain at the amplification line P(20) in the band of transition 00°1-10°0 is the most significant even when compared with those at other amplification lines, and energy is concentrated to the amplification line P(20). However, in order to generate plasma for radiating EUV light, a laser beam having a short pulse width of about 20 ns to 50 ns is necessary. In order to efficiently amplitude the laser beam having such a short pulse width, it is known that the multiline amplification type of amplifying the laser beam at plural amplification lines is suitable. In the case of performing the multiline amplification, seed light having wavelengths at amplification lines P(20), P(18), P(16) in the band of transition 00°1-10°0 and an amplification line P(22) in the band of transition 00°1-02°0 can be amplified by being passed through a CO2 laser gas as a laser medium. Here, a wavelength at the amplification line P(22) in the band of transition 00°1-02°0 is about 9.56 μm. Therefore, in the case of using the amplification line in the band of transition 00°1-02°0, even if an arrangement of apertures having a pitch of, for example, 5.3 μm, which is equal to or less than a half of a wavelength of the general CO2 laser beam (10.6 μm), is formed in the SPF, a CO2 laser beam having a wavelength of 9.56 μm is transmitted without being reflected. In order to reflect the CO2 laser beam having a wavelength of 9.56 μm, the SPF formed with an arrangement of apertures having a pitch equal to or less than a half of the shortest wavelength among wavelengths of a laser beam applied by the driver laser is necessary. FIG. 15 shows a configuration of a CO2 laser system for performing multiline amplification at desired amplification lines. Plural semiconductor lasers for performing pulse oscillation in a single longitudinal mode in correspondence with wavelengths at plural amplification lines in a CO2 gas laser are used as master oscillators, and thereby, the multiline amplification can be realized. The CO2 laser system 60 includes plural semiconductor lasers 61, an optical multiplexer 62 for combining seed pulse light outputted from the plural semiconductor lasers 61, a preamplifier 63 for pre-amplifying the combined seed pulse light, and a main amplifier 64 for further amplifying the laser light pre-amplified by the preamplifier 63. Here, the preamplifier 63 and the main amplifier 64 use a laser gas containing a carbon dioxide gas (CO2) as a laser medium. By passing the seed pulse light at multi-lines through the laser medium, pulse amplification at multi-lines can be realized. The concrete example will be explained as follows. FIGS. 16A and 16B show intensity distribution in the case where intensity of wavelength components included in a laser beam outputted from a main amplifier is made uniform by adjusting light intensity in a longitudinal mode in oscillation of plural semiconductor lasers in correspondence with amplification ranges having different amplification gains. FIG. 16A shows a relationship between the amplification gains of a CO2 gas laser and light intensity of each semiconductor laser in the single longitudinal mode. For example, laser beams having five kinds of wavelengths outputted from five semiconductor lasers 1-5 are assigned to an amplification line P(22) in the band of transition 00°1-02°0 and amplification lines P(18), P(24), P(26), P(28) in the band of transition 00°1-10°0, respectively. Since gains are different among those amplification lines, intensity and wavelength of each semiconductor laser is adjusted in agree with the gain at respective one of the amplification lines. Specifically, intensity of the semiconductor laserbeam, which is assigned to an amplification line with a large gain, is set small, while intensity of the semiconductor laser beam, which is assigned to an amplification line with a small gain, is set large. Thereby, as shown in FIG. 16B, it becomes possible that light intensity of plural lines is made substantially uniform. As a result, the amplification efficiency is improved in comparison with that in a single-line amplification. Although the multiline amplification in a CO2 laser is simply explained in a schematic manner in this embodiment, a regenerative amplifier may be used according to need, in order to efficiently amplify seed pulse light having small light intensity after semiconductor laser beams are combined. Further, plural preamplifiers or plural main amplifiers may be arranged in serial for amplification, in order to obtain high output. In the case where the above-mentioned CO2 laser system for performing multiline amplification is used as the driver laser of the EUV light source apparatus, in the SPF as shown in FIG. 2 or 5, a pitch of the arrangement of apertures is set equal to or less than a half of the shortest wavelength among wavelengths of a CO2 laser beam applied by the driver laser. Further, in the SPF as shown in FIG. 12, a pitch of the wires is set equal to or less than a half of the shortest wavelength among wavelengths of a CO2 laser beam applied by the driver laser. For example, in the case where the shortest wavelength among wavelengths of a CO2 laser beam applied by the driver laser is 9.56 μm, the pitch of the apertures or the pitch of the wires is set equal to or less than 4.78 μm.
042696585	summary
	claims	1. A spectrometer for positron lifetime characterization studies, wherein a DC positron beam is directed onto a sample surface to produce annihilation gamma radiation and secondary electrons from the sample, the annihilation gamma radiation is detected by a gamma detector, and the secondary electrons are detected by an electron detector, comprising: wherein: an entrance grid situated in the incident positron beam, said entrance grid positioned parallel to the sample surface, and said entrance grid arranged to have a higher electrical potential than the sample potential; the entrance face of the electron detector assembly is situated parallel to the entrance grid, the entrance face of the electron detector assembly is arranged to have the same potential as the entrance grid, and the sample surface, said entrance grid, and said entrance face of said electron detector assembly are disposed at a tilt angle to the incident DC positron beam. 2. The spectrometer of claim 1 wherein said tilt angle is such that the electron detector does not physically block the incoming positron beam. claim 1 3. The spectrometer of claim 1 wherein the secondary electrons generated by the bombardment of the primary positrons on the sample start the positron lifetime clock, and the detection signal of the annihilation gamma radiation of the positrons stops the positron lifetime clock. claim 1 4. The spectrometer of claim 1 further including a time delay that delays the secondary electron signal so that the detection signal of the annihilation gamma radiation of the positrons starts the positron lifetime clock, and the secondary electrons generated by bombardment of the primary positrons on the sample stops the positron lifetime clock. claim 1
054988250	summary	TECHNICAL FIELD The present invention relates generally, as is indicated, to a plutonium and nuclear toxic waste storage depot and method and, more particularly, to a facility and a method for storing plutonium and nuclear toxic waste material by using a recirculating system in addition to a massive structure that is economically feasible. The invention also relates to encasement of asbestos, lead and other toxic waste by an encasing material that includes a resin and epsom salt, such as that sold under the trademark STAYTEX.RTM., for disposal in ordinary land fills Cross reference is made to copending, commonly owned U.S. Patent application Ser. No. 08/064,548, filed May 19, 1993, entitled Environmental Non-Toxic Encasement Systems for Covering In-Place Asbestos and Lead Paint, the entire disclosure of which hereby is incorporated by reference. Cross reference also is made to U.S. Pat. No. 4,122,203, the entire disclosure of which also hereby is incorporated by reference. BACKGROUND The storage of plutonium and nuclear toxic waste is becoming evermore a problem. A problem with plutonium and other nuclear waste is the need to store such waste for a very long time in view of the relatively long half-life of such material. For example, some nuclear waste material have a halfolife that is more than 100 years. Substantial exposure to nuclear material can be a health hazard and, in fact, can be fatal. One technique for storing plutonium and other nuclear waste has been to place the waste in a container and to bury the container. (Hereinbelow, reference to nuclear waste includes plutonium as well as other nuclear materials, especially those which emit nuclear radiation.) A disadvantage to this technique is the possibility that the container can rust or otherwise corrode, and the nuclear waste can leak. For example, if the nuclear waste were to leak into the ground, it could contaminate the ground water and eventually cause harm to animals, fish, vegetable life, and possibly to humans. Another disadvantage is that the radiation from the nuclear waste can too easily be emitted into the external environment causing a health hazard, for example. One technique for shielding nuclear waste has been to provide several inches, for example, at least three inches of lead shielding, to surround the nuclear waste. Such lead shielding tends to prevent the transmission of radiation to the external environment. Another technique has been to use at least three feet of water placed between the nuclear waste and the external environment to prevent transmission of radiation to the external environment. Storage of non-radioactive toxic waste also presents problems similar to those encountered with the storage of toxic nuclear waste. For example, if the toxic waste were placed in drums and buried, leakage due to rusting or corrosion can cause contamination of drinking water and other waters used by fish, animals and plant life. A difficulty encountered when storing toxic waste, whether nuclear or non-radioactive, is the heat often generated during storage. Excessive heat can trigger undesirable reactions, including the possibility of explosive activity. This, of course, is undesirable, as it tends to result in a release of the toxic waste to the external environment. One reason that nuclear waste has been buried in the ground in the past has been the good shielding provided by the ground. Also, prior above ground shelters considered for storing nuclear and other toxic waste contemplate or use concrete and metal wall and roofs; the heavy weight of the roof makes design and construction difficult and sturdiness of the structure questionable. If such structures are used, of necessity they must be small. Today there is no way permanently or substantially permanently to store large quantities of plutonium. Since 1988 over $20 billion has been spent by the U.S. Department of Energy for disposing of nuclear waste; but there has been no improvement in methods and techniques according the Secretary of the Department of Energy. However, when using the ground for shielding, a problem is encountered in the case of a spillage, leak, etc. of the primary containment medium, such as a metal drum or the like. Encasement using STAYTEX.RTM. material can be used for asbestos, lead, etc. for disposal in ordinary landfills. An example of such encasement is described in commonly owned pending U.S. patent application Ser. No. 08/064,548 filed May 19, 1993. With the foregoing in mind, it will be appreciated that improvements in storage of toxic waste, both of the nuclear type and the non-radioactive type are desired. SUMMARY An aspect of the invention relates to the use of a fluid material, such as a slurry, which contains a material intended to receive and to collect nuclear radiation, while preferably also blocking transmission of the nuclear radiation, and precipitating out such material from the fluid material for subsequent storage of the precipitated material. An exemplary material contained in the fluid or slurry mentioned in the preceding paragraph is epsom salt; and, therefore, an aspect is the use of epsom salt as summarized in the preceding paragraph. Another aspect of the invention relates to a toxic waste storage depot where toxic waste can be stored, including a building have a portion located below ground, walls for bounding an interior space in the building, and fluid for removing thermal energy from the building and for providing radioactive shielding, at least as a part of the building. According to .another aspect of the invention, a toxic waste storage depot uses the shielding effect of the ground to tend to prevent leakage of radiation in combination with a fluid of specific gravity characteristics greater than those of water to provide both radioactive shielding and thermal energy removal functions. A further aspect relates to the use of fluid, such as water, in combination with epsom salt or MgSO.sub.4.7H.sub.2 O to provide relatively high specific gravity slurry material to effect radiation shielding and thermal energy removal from a toxic waste storage facility. An aspect of the invention relates to a method of effecting radiation shielding and thermal energy removal from a toxic waste storage facility including using water in combination with epsom salt to provide relatively high specific gravity slurry material to block transmission of radiation and to remove thermal energy. Another aspect relates to a method of removing radioactivity from the interior of a building by transporting radioactive material within a slurry and filtering out the then contaminated material outside the building, thus removing it in a continuous fluid recirculation system. A further aspect relates to a toxic waste storage facility including a building having a portion located below ground level, walls for bounding an interior space in the building, and fluid for removing thermal energy from the building and for providing radioactive shielding at least at part of the roof of the building. An additional aspect relates to a toxic waste depot method including using the shielding effect of the ground to tend to prevent leakage of radiation in combination with a fluid of specific gravity characteristic greater than that of water to provide both radioactive shielding and thermal energy removal functions. Yet another aspect relates to a method of disposing of toxic material, such as asbestos, lead, and the like, including encasing the toxic material in a cured resin system including at least one liquid thermosetting resin having particulate solids dispersed therein, about 100% of the solids having a U.S. Standard mesh size of about 225 mesh or smaller and at least about 10% of the solids having a U.S. Standard mesh size of about 325 mesh or smaller, wherein the solids comprise crystalline hydrated inorganic salts, and placing the encased material in a conventional land fill. These and other objects, aspects, features and advantages of the present invention will become more apparent as the following description proceeds. To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings setting forth in detail a certain illustrative embodiment of the invention. This embodiment is indicative, however, of but one of the various ways in which the principles of the invention may be employed. Although the invention is shown and described with respect to a certain embodiment, it is obvious that equivalents and modifications will occur to others who have ordinary skill in the art upon reading and understanding the specification. The present invention includes all such equivalents and modifications and is limited only by the scope of the claims.

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