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051184621	summary	The invention relates to a manipulator for handling operations, particularly for non-destructive testing, in the vicinity of the nozzle of a vessel in the primary loop of a nuclear power plant. The invention also relates to a method for handling a device, in particular for handling a test head or probe. The nozzles on the vessels in the primary loop are among the highly stressed parts of a nuclear power plant. The weld seams and the inner radius of the nozzles must therefore be tested regularly by non-destructive methods. It is known to perform such tests with a manipulator that has an outrigger which is radial to the nozzle and a probe that is axially displaceable on the outrigger. The manipulator slides on an annular rail that surrounds the nozzle to be tested. In order to execute the required motions in the test operations, the manipulator has a respective drive mechanism for each of the circumferential and radial directions. The outrigger in the radial direction is pressed by mechanical devices against the outer vessel wall to be tested and is aligned tangentially. The vessel having the nozzle to be tested is surrounded by a biological shield and insulation. Since the gap between the vessel and the insulation or the biological shield is sometimes quite narrow, it is very difficult to introduce the conventional manipulator into the annular gap and in fact it is not always possible, because the required structural height of the known outrigger prevents its use with a very narrow annular gap. During testing, the probe must be moved around the neck on concentric or elliptical paths. Due to testing technique requirements, it is necessary to use various probes, which must be manually changed in the course of a test. The testing is made more difficult by the increased radiation in the vicinity of the test specimen, and by the cramped conditions. In the known apparatus, changing the probe requires manual disassembly of the manipulator and is therefore very time-consuming and entails considerable radiation exposure to personnel. Moreover, it is not always possible to circumvent obstacles in the test region, because the radial outrigger has a bottom frame with a spindle extending over its entire length for moving the probe and as a result it projects quite far outward. It is accordingly an object of the invention to provide a manipulator for handling operations, particularly for non-destructive testing, and a method for handling a device, which overcome the hereinafore-mentioned disadvantages of the heretofore-known methods and devices of this general type, which can be introduced into the annular gap more easily than before and which can also work in very narrow annular gaps. Moreover, the manipulator should make it possible to shorten the time required for changing the probe and for reducing the exposure load to operating personnel and the method should enable remote-controlled handling of a device by a manipulator under cramped conditions. With the foregoing and other objects in view there is provided, in accordance with the invention, a manipulator for handling operations particularly for non-destructive testing in the vicinity of the nozzle of a vessel, especially in the primary loop of a nuclear power plant, comprising a carriage being movable in circumferential direction of a nozzle of a vessel, a sled being disposed on the carriage and displaceable in the axial direction of the nozzle, a shoulder joint disposed on the sled, a scissors half having an upper arm with one end supported in the shoulder joint and another end, a lower arm with a free end, another joint connecting the other end of the upper arm to the lower arm, a holder, a further joint connecting the holder to the free end of the lower arm, and a tool or a probe disposed on the holder. In this way, a very slender structure is attained, which makes it possible to use the manipulator in cramped spaces, and above all enables good adaptation to the curvature of the annular gap in the region of the nozzle. Obstacles in the test region can be circumvented by retracting the outrigger, because the lower arm can not only be pivoted but can also be moved in the axial direction of the nozzle. The manipulator also not only makes it possible to drive along the test regions on the vessel but also along all of the test regions on the nozzle jacket. The arms of the manipulator can be positioned in three dimensions. The manipulator is therefore not only suitable for testing purposes, but also for handling operations on the nozzle and in the annular gap. In accordance with another feature of the invention, there is provided a rack drive mechanism for displaceably supporting the shoulder joint on the sled. In accordance with a further feature of the invention, the rack drive mechanism has a rack being disposed on the carriage and having a toothless guide element for rerailing and derailing the sled. In accordance with an added feature of the invention, there is provided drive motor with a position transducer and a gear operatively connecting the drive motor and the sled for adjusting the position of the sled, and a control device connected to the position transducer, and/or another drive motor with another position transducer and another gear operatively connecting the other drive motor and the shoulder joint for adjusting a pivoting angle of the upper arm, the control device being connected to the other position transducer, and/or a further drive motor with a further position transducer and a further gear operatively connecting the further drive motor and the other joint for adjusting a pivoting angle between the upper and lower arms, the control device being connected to the further position transducer. The gears may be bevel gears. In accordance with an additional feature of the invention, the other joint includes means for permitting the lower arm to be folded back onto the upper arm, and the shoulder joint includes means for permitting the upper arm to be folded onto the carriage. In accordance with yet another feature of the invention, the lower arm has a shorter length than the upper arm, which is preferably approximately two-thirds the length of the upper arm. In accordance with yet a further feature of the invention, there is provided an annular rail disposed concentrically about the nozzle of the vessel, and means for derailing the carriage from and rerailing the carriage onto the rail. With the objects of the invention in view, there is also provided a method for handling a device, particularly a probe, in the vicinity of the nozzle of a vessel, especially in the primary loop of a nuclear power plant, with a manipulator, the manipulator including a carriage movable in circumferential direction of the nozzle, a sled being disposed on the carriage and displaceable in axial direction of the nozzle, a shoulder joint disposed on the sled, a scissors half having an upper arm with one end supported in the shoulder joint and another end, a lower arm with a free end, another joint connecting the other end of the upper arm to the lower arm, a holder, a further joint connecting the holder to the free end of the lower arm, and at least one drive motor operatively connected to at least one of the arms, and the method comprises controlling the holder and the other joint along a predetermined path with a control device acting upon the at least one drive motor, varying a pivoting angle of at least one of the arms with the at least one drive motor, optionally varying a position of the sled with a drive motor operatively connected to the sled, and optionally connecting a tool or a probe to the free end of the lower arm with the holder. In accordance with another mode of the invention, there is provided a method which comprises controlling the other joint along a path at least approximately parallel to a surface to be tested. In accordance with a concomitant mode of the invention, there is provided a method which comprises folding the lower arm back onto the upper arm and folding the upper arm onto the carriage, folding the probe or the tool onto the sled, changing the probe or the tool, and introducing or removing the manipulator through an opening in a biological shield into an annular gap between the vessel and the biological shield. Other features which are considered as characteristic for the invention are set forth in the appended claims. Although the invention is illustrated and described herein as embodied in a manipulator for handling operations, particularly for non-destructive testing, and a method for handling a device, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
	claims	1. A plasma doping method for forming an impurity doped layer in a substrate to be processed, the plasma doping method comprising:a step (a) of preparing a vacuum chamber having an inner wall on which a film containing a first impurity is formed;a step (b) of, after the step (a), placing the substrate to be processed on a sample table; anda step (c) of, after the step (b), generating plasma including a second impurity in the vacuum chamber and supplying high-frequency power to an electrode having the sample table so as to dope the first impurity and the second impurity into the substrate to be processed and to form the impurity doped layer,wherein the inner wall surrounds the sample table on which the substrate to be processed is placed. 2. The plasma doping method according to claim 1, wherein, in the step (c), a dose of the first impurity to be doped into the impurity doped layer is larger than a dose of the second impurity. 3. The plasma doping method according to claim 1, wherein, in the step (c), the second impurity is doped into the substrate to be processed by irradiating the plasma containing the second impurity, and the first impurity to be sputtered and emitted when the film containing the first impurity is exposed to the plasma is doped into the substrate to be processed. 4. The plasma doping method according to claim 1, wherein the first impurity and the second impurity are the same impurity. 5. The plasma doping method according to claim 1,wherein the substrate is a semiconductor substrate; andin the step (a), the film containing the first impurity is set such that the total distribution of the distribution of the second impurity to be doped from the plasma containing the second impurity and the distribution of the first impurity to be doped from the film containing the first impurity is made uniform in a surface of the semiconductor substrate. 6. The plasma doping method according to claim 1,wherein the inner wall is an inner wall of the vacuum chamber. 7. The plasma doping method according to claim 1,wherein the formation of the impurity doped layer is performed using a plasma doping apparatus having the sample table, andthe step (a) includes a substep of providing the vacuum chamber, from which the film containing the first impurity is removed, in the plasma doping apparatus and then generating plasma containing the first impurity in the vacuum chamber so as to form the film containing the first impurity on the inner wall of the vacuum chamber. 8. The plasma doping method according to claim 1,wherein the formation of the impurity doped layer is performed using a plasma doping apparatus having the sample table, andthe step (a) includes:a step (a1) of providing the vacuum chamber, from which the film containing the first impurity is removed, in a plasma doping apparatus different from the plasma doping apparatus and then generating plasma containing the first impurity ions in the vacuum chamber so as to form the film containing the first impurity on the inner wall of the vacuum chamber; anda step (a2) of, after the step (a1), providing the vacuum chamber having the film containing the first impurity on the inner wall in the plasma doping apparatus. 9. The plasma doping method according to claim 1,wherein the inner wall is an inner wall of an inner chamber provided in the vacuum chamber. 10. The plasma doping method according to claim 1,wherein the formation of the impurity doped layer is performed using a plasma doping apparatus that is provided with a head plate having a plurality of gas outlet ports at a position facing the substrate to be processed placed on the sample table. 11. The plasma doping method according to claim 1,wherein the plasma containing the second impurity is plasma of gas containing boron. 12. The plasma doping method according to claim 11,wherein the gas containing boron is gas having boron and hydrogen molecules. 13. The plasma doping method according to claim 11,wherein the gas containing boron is diborane (B2H6). 14. The plasma doping method according to claim 1,wherein the plasma containing the second impurity is plasma of gas that is obtained by diluting gas having boron and hydrogen molecules with rare gas. 15. The plasma doping method according to claim 14,wherein the rare gas is an atom having an atomic weight equal to or less than neon. 16. The plasma doping method according to claim 14,wherein the rare gas is helium. 17. The plasma doping method according to claim 1,wherein the plasma containing the second impurity is plasma of gas that is obtained by diluting diborane (B2H6) with helium. 18. The plasma doping method according to claim 11,wherein an implantation depth of boron is in a range of 7.5 nm to 15.5 nm. 19. The plasma doping method according to claim 1,wherein, in the step (c), a temperature of the inner wall of the vacuum chamber is set to a desired temperature in a range of 40° C. to 90° C.
	claims	1. A radiographic shield comprising:a first half presenting a first face;a second half presenting a second face, the second face being engaged against the first face in a first position and being separated from the first face in a second position;wherein the first half includes a first convex curved protrusion and a first concave curved undercut recess and the second half includes a second convex curved protrusion and a second concave curved undercut recess, wherein, in the first position, the first convex curved protrusion is engaged within the second concave curved undercut recess and the second protrusion is engaged within the first concave curved undercut recess whereby the first half and the second half have a single degree of freedom of relative motion; anda passageway formed between the first face and the second face, the passageway including a first end opening and a second end opening, the passageway including a circuitous element wherein there is no line of sight between the first end opening and the second end opening, the passageway including a portion for shielding a radiographic source prior to projecting the radiographic source during a projector mode. 2. The radiographic shield of claim 1 wherein the first and second halves are comprised of tungsten. 3. The radiographic shield of claim 1 wherein the first half and the second half are manufactured from a single block of material using electrical discharge machining. 4. The radiographic shield of claim 1 wherein the circuitous element includes a central portion of the passageway which rises upwardly to prevent a line of sight between the first end opening and the second end opening. 5. The radiographic shield of claim 1 wherein the circuitous element includes an at least partially S-shaped element. 6. The radiographic shield of claim 1 further including a radiographic shutter mechanism for selectively opening and closing the passageway. 7. The radiographic shield of claim 6 wherein the radiographic shutter is made from tungsten. 8. The radiographic shield of claim 6 wherein the radiographic shutter is manually operated. 9. The radiographic shield of claim 8 further including a screw for manual operation of the radiographic shutter.
	summary
	abstract	A shipping container comprises a tubular or cylindrical shell having a closed end and an open end, a top end-cap removably secured to the open end of the tubular or cylindrical shell, and at least one fuel assembly compartment defined inside the shell. Each fuel assembly compartment includes elastomeric sidewalls and is sized and shaped to receive an unirradiated nuclear fuel assembly through the open end of the shell. The shipping container may further include a divider component, for example having a cross-shaped cross-section with ends of the cross secured to inner walls of the shell, and the divider component and the inner walls of the shell define the fuel assembly compartments. To load, the shipping container is arranged vertically and an unirradiated nuclear fuel assembly is loaded through the open end of the shell into each compartment, after which the open end is closed off by securing the top end-cap.
	summary
	description	The present invention generally relates to the use of photoreactive compound materials, and more particularly to the use of photoreactive compound materials to irreversibly change the appearance of a housing for a variety of devices. The market for electronic devices, especially personal portable electronic devices, for example, cell phones, personal digital assistants (PDA's), digital cameras, and music playback devices (MP3), is very competitive. Manufacturers are constantly improving their product with each model in an attempt to cut costs and to meet production requirements. The look and feel of personal portable electronics devices is now a key product differentiator and one of the most significant reasons that consumers choose specific models. From a business standpoint, outstanding designs (form and appearance) may increase market share and margin. Consumers are enamored with appearance features that reflect personal style and select personal portable electronics devices for some of the same reasons that they select clothing styles, clothing colors, and fashion accessories. Consumers desire the ability to change the appearance of their portable electronics devices (cell phones, MP3 players, etc.). Plastic snap-on covers for devices such as cell phones and MP3 players can be purchased in pre-defined patterns and colors. The types of electro-optical modules that one could affix or embed in a portable electronic device to enable a changing appearance are limited by a number of factors. Portable electronic devices must be particularly thin, robust, and low power. Sales of high volume consumer products are very sensitive to consumer preferences for design, functionality, and cost. These factors produce a narrow engineering window requiring unique solutions. Accordingly, it is desirable to provide a method and apparatus for changing the appearance of a device housing. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background. The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any theory presented in the preceding background or the following detailed description. Housings are used to contain or store, and protect, a wide variety of items or devices and typically are a rigid or flexible material of a specific color. The term “housing” generally refers to a material at least partially covering or surrounding an item, and may assume other names such as a “case”, for example. Items disposed within a housing range, for example, from keepsakes such as jewelry to electronic devices such as cell phones. The housing described herein includes a transparent support layer, a photoreactive coating, a radiation attenuating material, an optional background color layer, an optional activating radiation source, and an optional patterning layer. The transparent support layer provides structure to the housing. The radiation attenuating material, transparent to visible light, absorbs radiation, such as ultraviolet (UV) from sunlight, and prevents the unintentional changing of the color of the photochromic coating and degradation of the other layers beneath. The radiation attenuating material may be referred to as a blocking material when the UV radiation is substantially prevented from passing there through. When a slow color or design change is preferred, such as developing of patina effect, the UV blocking ability or efficiency can be engineered to allow, or attenuate, a limited amount of UV to reach the photoreactive layer to slowly activate the process. The photoreactive coating may be photochromic ink of a solution of a 1,2-dihydroquinoline (DHQ) in a polymer solution that irreversibly changes color when exposed to activating radiation such as UV radiation. The photoreactive material may also be a photosensitive layer containing silver oxalate and mercury(I) and/or mercury(II) oxalate. Another example is pyrrole derivatives, such as 2-phenyl-di(2-pyrrole)methane, which becomes irreversibly red upon UV light exposure. The photoreactive coating may originally comprise a color or be clear, and is changed to a color, or from a color to clear, upon the application of radiation. As used herein when referring to the photoreactive coating, the word “color” includes a visible color or no visible color (clear). The optional background color layer provides an initial color to the housing, and may be a partially reflective layer of metallization. The background color may be provided alternatively by the transparent support layer or may be omitted altogether when a transparent housing is desired (for displaying objects within the housing). The radiation source may be for example, a light emitting diode (LED), which emits light at specific wavelengths, for example ultraviolet or fluorescent black light, that activate the color changing process of the photoreactive compounds. While UV radiation is preferred, other wavelengths may be used. Referring to FIG. 1, housing 100 includes a transparent support layer 104 having a UV blocking coating 102 formed thereon. While the transparent support layer 104 may be any known transparent material, a polymer material is preferred. The transparent support layer 104 provides protection to items within the housing, and a surface on which to apply the UV blocking coating 102 and the photoreactive coating 106. The UV blocking coating 102 is a material that contains compounds, such as Benzotriazole or Benzophenone, that absorbs UV radiation found in the ambient environment, for example, in the range of 280 to 400 that includes both UV-A and UV-B, and especially UV radiation within sunlight. The photoreactive coating 106 is a material of dye molecules that initially assumes a first color, then irreversibly changes to a second color upon the application of activating radiation. The second color remains when the activating radiation is removed. This material is, for example, preferably a matrix of 1,2-dihydroquinoline (DHQ) in polymer (See U.S. Pat. No. 4,812,171) or other materials such as a photosensitive layer containing silver oxalate and mercury(I) and/or mercury(II) oxalates, pyrrole derivatives, such as 2-phenyl-di(2-pyrrole)methane. A transparent colored layer 108 is disposed contiguous to the photochromic coating 106. The outer surface 110 of the UV blocking layer 102 is considered the outside of the housing while the inside surface 112 of the transparent colored layer 108 is the inside of the housing in which items (not shown) may be contained. Undesired UV radiation such as sunlight striking the surface 110 will not penetrate beyond the UV blocking coating 102 to the photochromic coating 106. However, a user of the device viewing the outer surface 110 will view the color presented by the colored layer 108 since the UV blocking coating 102, support layer 104, and photochromic coating 106 are transparent to frequencies in the visual range of approximately 400 to 780 nanometers. Note that the colored layer 108 is optional, in which case the housing 100 is transparent, enabling the contents of the housing 100 to be viewed. Referring to FIG. 2, a light source 122 such as a light emitting diode provides activating radiation 124 to the inside surface 112 of the housing 100. The activating radiation 124 passes through the transparent colored layer 108 and strikes the photochromic coating 106, causing it to irreversibly assume a color as indicated by the crosshatching within photochromic coating 106 of FIG. 2. The color in which the photochromic coating 106 changes depends on the chemicals contained therein and its thickness. Examples of chemicals for the irreversible photochromic coating 106 include 1,2-dihydroquinoline (DHQ) in a polymer solution, a photosensitive layer containing silver oxalate and mercury(I) and/or mercury(II) oxalates, pyrrole derivatives, such as 2-phenyl-di(2-pyrrole)methane. The thickness of the photochromic coating 106 preferably includes the range of 0.1 micron to 100 microns. The housing then exhibits the color, viewing towards the outside surface 100, combined from the colors of the colored layer 108 and the photochromic coating 106. For example, if the color of the colored layer 108 is blue and the color assumed by the photochromic coating 106 is yellow, a green color would be presented at the surface 110. FIG. 3 shows a second exemplary embodiment of a housing 300 including the UV blocking coating 102, transparent support layer 104, photochromic coating 106, and transparent colored layer 108 as described for the housing 100. A UV blocking layer 330 is patterned on the transparent colored layer 108 resulting in a light source 322 such as a light emitting diode provides activating radiation 324 through the patterned material 332 to the inside surface 112 in the gaps between the material 332 of the patterned layer 330, causing the area 326 to change to a color (as indicated by the crosshatching). FIG. 4 is taken along line 4-4 of FIG. 3, showing the patterned material 332 of the patterned layer 330 forming a fanciful pattern formed on the colored layer 108. FIG. 5 is the result showing the color and pattern looking at the surface 110 of the UV blocking coating 102 of the housing 300 in which the patterned material is distinctly seen through the transparent layers 104 and 102. FIG. 6 is a third exemplary embodiment of a housing 600 similar to the second exemplary embodiment of FIG. 3; however, the colored layer 108 is disposed between the UV blocking coating 102 and the transparent support layer 104. Note in this third exemplary embodiment, the colored layer 108 need not be transparent to the activating radiation. Instead of the light sources 122, 322, a fourth alternate exemplary embodiment includes a door, or sealable opening, that may be opened to allow sunlight to enter, striking the photochromic coatings 106, causing it to change colors and/or pattern. Referring to FIG. 7, a fifth exemplary embodiment includes a housing 700 having a UV attenuating layer 702 formed over the photochromic coating 106, and the transparent support layer 104 disposed between the photochromic coating 106 and the colored layer 108. The UV attenuating layer only partially blocks UV radiation, for example from sunlight, resulting in the color of the photochromic coating 106 slowly changing color over time. Depending on the thickness and the chemical makeup of the attenuating layer and the photochromic coating 106, this change in color may take days to weeks or more. Additionally, the patterned layer 330 may be included to cause a change in pattern over time. There are many variations to the above described embodiments. As mentioned, the colored layer 108 is optional (the housing may be transparent or the color may integrated within the transparent support layer 106) and may be disposed on either side of the support layer 104 or the photochromic coating 106. The photochromic coating 106 may be disposed on either side of the support layer 104 or may be integrated within the support layer 104. The disposition of the patterned layer 330 is also variable as long as it is disposed between the photochromic coating 106 and the source of radiation. Although the housing 100, 300 described herein may be used to house many types of devices, FIG. 8 shows in schematic form a mobile communication device, which may be used with the exemplary embodiments of the housing 100, 300 described herein, and includes a touchscreen display 812 formed within the housing 100, 300. Conventional mobile communication devices also include, for example, an antenna and other inputs which are omitted from the figure for simplicity. Circuitry (not shown) is coupled to each of the display 812, and typically a speaker and microphone (not shown). An icon 814 is disposed below the touchscreen display 812. It is also noted that the portable electronic device 800 may comprise a variety of form factors, for example, a “foldable” cell phone. While this embodiment is a portable mobile communication device, the present invention may be incorporated within any electronic device having a housing that incorporates an electro-optical module to change colors and/or patterns. Other portable applications include, for example, a laptop computer, personal digital assistant (PDA), digital camera, or a music playback device (e.g., MP3 player). Non-portable applications include, for example, car radios, stainless steel refrigerators, watches, and stereo systems. The low power requirements of the exemplary embodiments, specifically the light source providing UV radiation, presented herein make them particularly well suited to portable electronics devices. A sixth embodiment includes disposing an LED so as to irradiate only of a portion of the housing 100, 300. For example, referring to the device 800 shown in FIG. 9, only the area 916 surrounding the touchscreen display 812 is irradiated (as shown by the cross hatching) by one light source 324. Another light source 324 may selective irradiate the icon 814. Although only two light sources 322 are described with the exemplary embodiment of device 900, many more light sources 322 may be disposed within the housing 100, 300 to irradiate various portions of the device 900. Additionally, the photochromic coating 106 may be disposed in selective positions, such as behind only the icon 918, and then irradiated. The exemplary embodiments described herein provides an easy, inexpensive way for users to irreversibly customize the appearance of a device's housing, while requiring little or no power requirements. While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment of the invention, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the invention as set forth in the appended claims.
061921009	claims	1. A pellicle member for protection of an X-ray exposure area absorber pattern that is positioned on and that extends a distance from a surface of a circular X-ray mask having an outside diameter and a support ring with a shoulder extending beyond said outside diameter, comprising in combination: a subassembly of a circular membrane member on a washer shaped spacer member, retention means adapted to retain said subassembly to said mask as an assembly, in which, a mask protecting pellicle, said pellicle including a membrane member on a washer shaped spacer member sub assembly, said membrane member being positioned in contact with all of said first surface of said spacer member and having a thickness dimension that is small relative to said thickness dimension of said spacer member, and, retention means adapted to retain said subassembly to said X-ray pattern reproduction mask as an assembly, in which said second surface of said spacer member is in contact with said second bulk mask support surface from which said absorber pattern extends. 2. The pellicle member of claim 1 where said retention means is an electrostatic charge across the interface of said mask and said spacer member. 3. The pellicle member of claim 1 wherein said membrane member is of a material that is a member of the group of Si, Si.sub.3 N.sub.4, SiC and Diamond. 4. The pellicle member of claim 3 wherein said spacer member is of boron doped silicon. 5. The pellicle member of claim 3 wherein said support ring is of pyrex material. 6. The pellicle member of claim 5 wherein absorber pattern is of a material taken from the group of Au, W or TaSi. 7. The pellicle member of claim 1 wherein said mask support ring shoulder portion has an outside diameter that is greater than said outside diameter of said mask and said retention means includes at least one ring member and first and second attachments said first attachment being of a first portion of said at least one ring member to said shoulder portion by at least one of adhesive and screw means, and said second attachment being of a second portion of said at least one ring member to an extending portion of said second surface of said spacer by adhesive means. 8. The pellicle member of claim 7 wherein said retention means is a single ring member having an inside diameter that fits over said outside diameter of said mask, said first attachment being of a first portion of said single ring member to said shoulder portion by adhesive means, and said second attachment being of a second portion of said single ring member to an extending portion of said second surface of said spacer by adhesive means. 9. The pellicle member of claim 7 wherein said retention means is a single ring member having an inside diameter that fits over said outside diameter of said mask, said first attachment being of a first portion of said single ring member to said shoulder portion by screw means, and said second attachment being of a second portion of said single ring member to an extending portion of said second surface of said spacer by adhesive means. 10. The pellicle member of claim 7 wherein said retention means is superimposed first and second ring members each having an inside diameter that fits over said outside diameter of said mask, and being connected by a spring surrounding a rod between said first and second rings, said first attachment being of said first of said superimposed rings to said shoulder portion by screw means, and said second attachment being of said second of said superimposed rings to an extending portion of said second surface of said spacer by adhesive means. 11. The pellicle member of claim 7 wherein said retention means is superimposed first and second ring members each having an inside diameter that fits over said outside diameter of said mask, and being connected by an elastomer member adhesively attached to each said superimposed ring and extending across the intersection between them, said first said superimposed rings being attached to said shoulder portion by screw means, and said second of said superimposed rings being attached to an extending portion of said second surface of said spacer by adhesive means. 12. The pellicle member of claim 7 wherein said retention means is first and second ring members, said first ring member having an inside diameter that fits over said outside diameter of said mask, and being adhesively attached to said mask and to said shoulder and having threads on the outside diameter, said second ring member being attached to an extending portion of said second surface of said spacer by adhesive means and having threads in the inside diameter thereof that mesh with said threads on the outside diameter of said first ring member. 13. The pellicle member of claim 7 wherein said retention means is a single ring member having an inside diameter that fits over said outside diameter of said mask, said single ring member further having partial cuts producing bendable tabs that when bent inward provide a friction grip of said mask, and, attachment of an edge of said ring member to an extending portion of said second surface of said spacer by adhesive means. 14. In a pattern reproduction mask for use with X-rays wherein a circular bulk mask support member having first and second essentially parallel surfaces is supported at the periphery by a ring member, said bulk mask support member having a central thinned region in said first surface and having an absorber pattern of X-ray opaque material on said second surface in registration with said thinned region, the improvement comprising: 15. The improvement of claim 14 wherein said membrane member is of a material that is a member of the group of Si, Si.sub.3 N.sub.4, SiC and Diamond. 16. The improvement of claim 15 wherein said spacer member is of boron doped silicon. 17. The improvement of claim 16 wherein said support ring is of pyrex material. 18. The improvement of claim 17 wherein said absorber pattern is of a material taken from the group of Au, W or TaSi.
	abstract	A method, system, and apparatus are disclosed for a complex shape structure for liquid lithium first walls of fusion power reactor environments. In particular, the method involves installing at least one tile on the surface area of the internal walls of the reactor chamber. The tile(s) is manufactured from a high-temperature resistant, porous open-cell material. The method further involves flowing liquid lithium into the tile(s). Further, the method involves circulating the liquid lithium throughout the interior network of the tile(s) to allow for the liquid lithium to reach the external surface of the tile(s) that faces the interior of the reactor chamber. In addition, the method involves outputting the circulated liquid lithium from the tile(s). In one or more embodiments, the reactor chamber is employed in a fusion reactor. In some embodiments, the tile is manufactured from a ceramic material or a metallic foam.
044538570	description	In practice of the present invention, hazardous or toxic material to be stored is first sealed into containers, preferably of uniform size, for transport to and handling at the disposal site. For many materials, the standard 55 gallon metal drum, 10 are entirely satisfactory. However, corrosive or highly radioactive materials will require containers of more specialized construction such as polymeric drums for corrosives and lead shielded containers for radioactive waste. The primary requirements of the containers employed are that the container possess adequate integrity to safely contain the particular material involved; and that the container possesses sufficient strength and rigidity to withstand the handling operations to which it will be subjected and the pressures applied by the static head of concrete as concrete is poured around and above the container during the storage process. Details of each particular installation will vary in accordance with its location, soil conditions and type of waste being handled, however, the basic technique is to first form at a suitable depth below ground level an open topped concrete chamber. In a typical case, the chamber includes a floor 12 with a thickness of about three feet. The floor 12 has a continuous channel 14 formed around the outer edge of the floor. Continuous side 16 and end 18 walls of one or more feet thickness are poured to form the enclosed concrete chamber. The side and end walls 16, 18 are formed with a continuous bead 20 at the lower surface where the walls meet the floor. The bead 20 and channel 14 form a mechanical joint which serves to consolidate the chamber structure and prevent the movements of the parts relative to each other. A polymeric shield 22 is shown disposed within the joint. The shield has enlarged portions 24 which are disposed in the floor and walls thereby anchoring the shield within the chamber. The enlarged ends 24 are connected by a web 26 which passes transversely through the joint formed by the channel 14 and bead 20. The web 26 is essentially a continuous barrier which will minimize any leakage through the joint. The side walls 16 and end walls 18 are poured with divider walls 28. The divider walls form compartments within the chamber. The chambers allow the storage of several kinds of hazardous material in the same chamber while keeping the materials separated. While the materials may react violently if mixed, this system will serve to prevent such dangers. The separation walls 28 also provide structural integrity to the chamber and provide support keeping the walls separated. Further, it is only necessary to fill one compartment with containers prior to encasement of the layer. Therefore, only about one forth of the chamber need be filled prior to encasement. This allows smaller lots of material to ensure the containerized waste is exposed to the surroundings for a shorter period of time prior to encasement which lessens the chance of an accident to one or more containers. As shown the divider walls 28 also have a mechanical joint with the floor. The depth of the concrete container ground will be selected in accordance with the total number of containers 10 to be stored, which will also determine the height of the side and end walls, with provision being made for covering the completed installation with fill to an adequate depth. The manner in which the floor, side and end walls are poured, the placing of reinforcing grids or bars within the poured material, etc. will be determined in accordance with standard construction practices, soil conditions, etc. After the sides 16, floor 12 and end walls 18 have cured, containers 10 are placed on the floor of the chamber until the floor of one chamber is filled. In the usual case, the containers will be cylindrical and thus even when placed in side to side contact with each other, will provide spaces between the individual containers. In same cases, the properties of the waste material may be such that the containers will be located on the floor out of contact with each other, by distances determined by the property of the material or the container. In any case, it is desirable that spaces or voids be left between the containers as explained below. After the containers 10 are placed on the floor 12, concrete is poured into the chamber to a depth which will cover the containers so as to form a floor for a subsequent layer of containers. Generally an amount which covers the container by three or more inches as shown at 30 will be sufficient. In the case where the material held in the container is of relatively low density a fixed grid of expanded metal or bars 32 can be secured to the chamber walls 16, 18 overlying the containers and preventing the containers from floating in the concrete as it is being poured. Where concrete rebar is used the retaining grid will serve the additional function of reinforcing the poured concrete. The concrete will fill the spaces between the containers as shown at 33 to form posts which support the subsequent layers of concrete and containers. After the concrete has been poured to the desired depth, completely covering and enclosing the containers on the chamber floor, the concrete is allowed to cure and a second layer of containers is then placed on the new floor of the chamber and the process repeated until the final or uppermost layer of containers is placed. The final pouring which encases the upper layer of containers 10 will close the concrete chamber forming a ceiling 34. The ceiling will normally be of substantial thickness, e.g. say three feet or more. As shown, the ceiling has a bead and channel interlock with a shield 22 disposed therein to prevent leakage into as well as out of the chamber preventing or minimizing liquid percolation through and around the containers 10, lessening the amount of contaminate leachment. After the ceiling 34 has cured, fill dirt is employed to cover the installation. Referring now to FIGS. 3, 4 and 5, a recovery systems suitable for supporting the concrete chamber of FIGS. 1 and 2 described in detail hereinbefore is shown. A one-piece subfloor 36 is formed with short vertical walls 38 extending upward. A plurality of spaced concrete pillars 40 are formed extending upward from the floor 36 within the periphery of the walls to provide supporting columns. The volume between the pillars 40 is filled with crushed concrete, large gravel, or other course filler 41 material which provides a certain measure of load supporting strength but which is porous and will allow any liquid leachate coming from the bottom of the chamber to flow freely into the well level disposed below the upper surface of the floor. A well 42 is shown formed at a location on the periphery of the floor 36. One or more of the wells 42 are formed as an integral part of the floor and depend downward from the floor to collect any leachate or liquid which escapes through the bottom or floor portion 12 of the concrete chamber. The upper surface 43 of the floor 36 will be shaped and slanted during construction so that any liquid on the upper surface flows to the well through the porous filler. As shown, the well 42 has a pipe 44 contained therein which is attached to a pump 46 adapted to withdraw liquid and pump it to the surface where any liquid containing contaminants can be placed in a container for storage. As shown in FIG. 4, the concrete chamber can be formed with a bottom wall which extends outward beyond the concrete chamber formed by the side walls 18 to form a shelf 48. The shelf 48 will have a recovery trench 50 formed as a continuous peripheral trench at a position several inches away from the walls. The recovery trench 50 and the area immediately above it would be back filled with crushed concrete or gravel 52 providing a porous media for several inches atop the recovery trench. Leachate, if any, from the concrete chamber will tend to flow down the walls into the porous gravel immediately above the shelf 48 and into the recovery trench 50. The trench is formed so that liquid therein drains into a lower recovery unit 52. Any leachate will be pumped to the surface by means of standard pumping techniques and the leachate processed and placed in suitable containers. Monitors can be placed in the pipes extending into the recovery wells to monitor the liquid within the wells. Such monitors can be installed to monitor the presence of organic chemicals, acids, bases, or radioactivity depending upon the type or types of material stored within the concrete chamber. Such sensors are known in the art and the particular monitor forms no part of this invention. With respect to the filler between the containers 10, alternative fillers can be used depending upon the material to be stored and the structural strength necessary. For example, the barrels can be surrounded with sand, aggregates, crushed rock or small stones which are tamped into a tight layer surrounding the containers. After the containers are surrounded with the crushed filler material, a layer of concrete of the desired thickness can be poured over the unit to create a sound solid structural floor for a second layer of containers with the process being repeated until the concrete chamber is full. The upper most layer of the unit forming the ceiling will be formed as described hereinabove with respect to FIGS. 1 and 2. Where desired, one or more of the chambers formed by the divider walls, side walls, end walls and floor can be sprayed with sealing materials. One example of a suitable sealing material is an isocyanate terminated polyurethane prepolymer. Such polymers have polyoxyethylene as a backbone prepolymer the polymers being miscible and reactive with water. Such polymers when sprayed on concrete have a tendency to be absorbed into the liquid generally present in concrete and react in situ with the ambient water to form a polyurea-urethane which seals the porous concrete. Other coating materials such as asphalt, and various other polymeric sealant materials are known in the art. Obviously, if so desired, the outer surface of the concrete chamber could be coated instead of the inner or both the inner and the outer surfaces could be coated with the same or different materials depending upon the desired structure. Examples of other suitable coating materials are polysulfide-epoxide resins, chloro-sulfonate polyethylene, polyvinyl chloride, polyvinyl acetate, lead metal, and polyethylene sheeting. Another structural material suitable for use in the practice of this invention is a material called polymeric concrete. Such structural material improves the durability and water-tightness of concrete structures and improves the concrete's resistance to corrosive environment. The material also provides improved strength and stiffness. In forming polymeric concrete, an organic monomer system is mixed into the concrete in addition to the water used in mixing the cement. One example of a suitable monomer system is methacrylate combined with trimethlopropane, trimethacrylate and azo bis-isobutyronitrile. Such a system will cure to a polymerized methylemthacrylate system which seals and consolidates the concrete or portland cement present in the concrete chamber. Examples of other suitable chemicals include trimethacrylate, dimethyl para toluidine. Such resin systems and suitable free radical catalysts are known in the art. As noted before, various isocyanate terminated polymers and prepolymers, urethanes or epoxides, can be added to the concrete mixture prior to pouring to provide materials which will react in situ to form a polymer within the concrete sealing the pores and preventing or at least minimizing, the flow of liquid into and out of the chamber. Various modifications and alterations of this invention will become apparent to those skilled in the art from the description of the new waste disposal system contained hereinbefore. It is understood that this invention is not limited to the illustrative embodiments described hereinbefore.
	description	This application is based upon and claims the benefits of priority from the prior Japanese Patent Applications No. 2002-337339 filed on Nov. 21, 2002 and No. 2003-75932 filed on Mar. 19, 2003; the entire contents of which are incorporated herein by reference. This invention is related generally to a system and a method for chemical decontamination of radioactive material, and more particularly to a system and a method for chemically dissolving oxide film on a surface of a contaminated component or the base material of the component. In a facility handling nuclear radiation, oxide film containing radioactive nuclides is adhered or generated on the internal surface of the constructional parts in contact with fluid containing radioactive material as the operation is continued. When the operational experience time becomes longer, the radiation level around the constructional parts such as piping and components becomes higher, the dosage the personnel would receive during periodic inspection or during demolishing in decommissioning of the facility would be increased. Practical chemical decontamination technique, by which the oxide film is chemically dissolved and removed has been developed to reduce dosage of personnel. Various chemical decontamination methods have been proposed. For example, a method is known which has a step of oxidizing and dissolving the chromium oxide in the oxide film with oxidizer agent and a step of reducing and dissolving the iron oxide which is a main component of the oxide film by reduction agent. Japanese Patent Publication (Tokkou) Hei-3-10919 discloses a chemical decontamination method where dicalboxylic acid (oxalic acid) aqueous solution is used as a reducer. According to this method, permanganic acid and oxalic acid are used. Permanganic acid has a strong oxidation effect with low concentration, and oxalic acid can be decomposed into carbon dioxide and water. Therefore, the amount of secondary waste material generation is reduced compared to the conventional chemical decontamination method. This method has been actually used in a decontamination work of a nuclear power facility. Japanese Patent Application Publication (Tokkai) 2000-81498 discloses a chemical decontamination method where ozone aqueous solution is used as an oxidizer and oxalic acid aqueous solution is used as a reducer. Ozone is decomposed into oxygen, and oxalic acid is decomposed into carbon dioxide and water. Therefore, this method is noted as a decontamination technique which can reduce secondary waste material. Japanese Patent Application Publication (Tokkai) Hei-9-113690 discloses a method for decontaminating stainless steel waste material in organic acid (oxalic acid or formic acid) aqueous solution. According to this method, a stainless steel component is set in contact with a metal component which has a lower potential than oxidation-reduction potential of stainless steel, and the base material of stainless steel is dissolved and decontaminated. Since a single organic acid aqueous solution process is used, the decontamination process is simple. In addition, since the base metal is dissolved, this method is effective as a method for decontaminating waste metal to a general industrial waste level of radioactivity. Japanese International Patent Application Publication (Tokuhyou) Hei-9-510784 (International Patent Application Publication WO 95/26555) discloses treatment of oxalic acid aqueous solution as a treatment of decontamination waste liquid. According to this reference, Fe3+ in the oxalic acid aqueous solution forms anions as a complex with oxalic acid. Fe3+ is reduced into Fe2+ by irradiation of ray (h ν), as shown in Equation (1) shown below:[Fe(C2O4)3]3−+hν-->FeII(C2O4)2+2CO2 (1) Then, Fe2+ in the oxalic acid aqueous solution can be separated by cation resins. Oxalic acid is decomposed by the oxidation effect of hydroxy radical or OH(radical), which is generated as a result of a reaction of hydrogen peroxide (H2O2) and Fe2+, and carbon dioxide and water are generated as shown in Equations (2) and (3) shown below:H2O2+Fe2+-->Fe3++OH−+OH(radical) (2)H2C2O4+2OH(radical)-->2CO2+2H2O (3) The techniques disclosed in the references cited above can be used as decontamination techniques for reducing dosage of personnel working for periodic inspection of nuclear facilities such as nuclear power plants. However, ultraviolet ray devices are required to reduce Fe3+ into Fe2+ when oxalic acid is used as a reducer. As the structure to be decontaminated becomes larger, the amount of the decontamination liquid increases, and the required ultraviolet ray device becomes larger, which results in enhanced cost for the device construction. In addition, required time period for dissolving oxalic acid becomes longer which results in longer decontamination work time period. In the technique disclosed in Japanese Patent Application Publication Hei-9-113690, formic acid is utilized as a decontamination agent. However, formic acid cannot be used in decontamination if the component to be decontaminated has to be in safe, because formic acid electro-chemically dissolves the base metal. Furthermore, simple treatment with only formic acid cannot dissolve and remove oxide film and iron oxide which have been generated on the surface of the components, and sufficient decontamination performance cannot be obtained. Japanese Patent Application Publication (Tokkai) Hei-2-222597 and Japanese International Patent Application Publication (Tokuhyou) 2002-513163 (International Patent Application Publication WO 99/56286) disclose chemical decontamination techniques for radioactive metal waste. Japanese Patent Application Publication Hei-2-222597 discloses a method where the component to be decontaminated is temporally electrolyzed and reduced in sulfuric acid aqueous solution, and the potential is lowered to corrosion region of stainless steel so that the base metal would be dissolved and decontaminated. Japanese International Patent Application Publication 2002-513163 cited above discloses a method of decontamination, where trivalent irons are reduced into bivalent irons by ultraviolet ray, and oxidation-reduction potential of organic acid aqueous solution is lowered to corrosion region of stainless steel so that the base metal would be dissolved and decontaminated. This reference also discloses a method for removing iron ions in organic acid aqueous solution by cation exchange resins. Since trivalent irons are in form of complexes with organic acid as complex anions, they cannot be removed by cation exchange resins. Therefore, trivalent irons are reduced into bivalent irons by irradiation of ultraviolet ray. Bivalent irons can be easily removed by cation exchange resins since bivalent iron oxalate complex would be less stable. According to the technique disclosed in Japanese Patent Application Publication Hei-2-222597 cited above, oxidation-reduction potential is enhanced when concentrations of iron ions and chromium ions dissolved in the decontamination liquid increase. Therefore, dissolving reaction of stainless steel ceases, and the decontamination performance would deteriorate. Since sulfuric acid is used as a decontamination agent, the decontamination waste liquid generated in the decontamination process cannot be accepted in the existing waste liquid process system of nuclear facility without modification. A dedicated neutralization treatment device and an aggregation/settling tank are required. The aggregation/settling tank is to be used for separating deposition, which is separated out as hydroxide, and clear supernatant liquid, which would result in higher cost for construction of the decontamination system. Furthermore, large amount of secondary waste material is generated in the neutralization process, and cost for disposing the waste material increases. According to the technique disclosed in Japanese International Patent Application Publication 2002-513163 cited above, the decontamination device itself in contact with the decontamination liquid would be corroded, since the potential is lowered by concentration control of the bivalent and trivalent irons in organic acid decontamination liquid. Especially, oxalic acid has larger corrosion rate compared to other organic acids. Therefore, the decontamination device made from stainless steel may have a failure due to corrosion. In addition, the metal removed by the ion exchange resins includes metal which has eluted from the decontamination device, so that another problem may be generated in increase of spent ion exchange resins. The present inventors have obtained new information by actually decontaminating components contaminated with radioactivity, using the technology disclosed in Japanese Patent Application Publication Hei-9-113690 cited above. The newly obtained information includes: (1) In a case of using organic acid as decontamination liquid, if only oxalic acid is used, decontamination performance is high because it reduces and dissolves iron oxide. However, it takes long time to decompose the oxalic acid. If only formic acid is used, it takes shorter time to decompose the formic acid compared with the oxalic acid. However, the decontamination performance is not high because formic acid would not dissolve iron oxide. (2) Similarly to the technology disclosed in Japanese Patent Application Publication Hei-2-222597 cited above, in a case of temporary potential control, oxidation-reduction potential of the decontamination liquid is enhanced, as the concentrations of iron ions and chromium ions dissolved in the decontamination liquid increase. Therefore, dissolving reaction of stainless steel ceases, and decontamination performance deteriorates. (3) When oxide film including chromium oxide film is generated or adhered on the surface of the component, decontamination performance can be enhanced by oxidizing-dissolving the chromium with oxidizer agent. The entire contents of the all references cited above are incorporated herein by reference. Accordingly, it is an object of the present invention to provide an improved system or method for chemical decontamination of radioactive material. The system or the method do not require a step or a device for reducing trivalent iron ions into bivalent iron ions, the dissolving rate is higher than those using oxalic acid, and have a decontamination performance equivalent to oxalic acid. It is another object of the present invention to provide an improved system or method for chemical decontamination of radioactive material, wherein the decontamination rate is high, corrosion of the decontamination device is evaded and amount of generated secondary waste is comparatively small. There has been provided, in accordance with an aspect of the present invention, a method for chemically decontaminating radioactive material, the method comprising: reducing-dissolving step for setting surface of radioactive material in contact with reducing decontamination liquid including mono-carboxylic acid and di-carboxylic acid as dissolvent; and oxidizing-dissolving step for setting the surface of the radioactive material in contact with oxidizing decontamination liquid including oxidizer. There has also been provided, in accordance with another aspect of the present invention, a system for chemically decontaminating radioactive material which forms a passage for liquid to flow through, the system comprising: a circulation loop connected to the passage for circulating the decontamination liquid, the circulation loop having: a decontamination agent feeder for feeding mono-carboxylic acid and di-carboxylic to the decontamination liquid; a hydrogen peroxide feeder for feeding hydrogen peroxide to the decontamination liquid; an ion exchanger for separating and removing metal ions in the decontamination liquid; and an ozonizer for injecting ozone into the decontamination liquid. There has also been provided, in accordance with another aspect of the present invention, a system for chemically decontaminating radioactive material, the system comprising: a decontamination tank for containing radioactive material and decontamination liquid; a direct current power source for providing potential between the radioactive material and an anode; and a circulation loop connected to the tank for circulating the decontamination liquid, the circulation loop having: a decontamination agent feeder for feeding mono-carboxylic acid and di-carboxylic acid into the decontamination liquid; a hydrogen peroxide feeder for feeding hydrogen peroxide into the decontamination liquid; an ion exchanger for separating and removing metal ions in the decontamination liquid; and an ozonizer for injecting ozone into the decontamination liquid. A first embodiment of a method and a system for chemically decontaminating radioactive material according to the present invention are now described with reference to FIGS. 1 through 4. In this embodiment, the oxide layer (or film) on the surface of the radioactive component is dissolved, but the base metal of the radioactive component is not dissolved and remain intact. FIG. 1 shows a first embodiment of a system used for chemically decontaminating radioactive material according to the present invention. The system is used for chemically decontaminating radioactive component (or contaminated component) 30 such as a pipe section which has a passage for decontamination liquid 1a to pass through. The system includes a circulation loop 2 which is connected to the radioactive component 30 to be decontaminated for circulating the decontamination liquid 1a. The circulation loop 2 includes a circulation pump 3, a heater 4, a decontamination agent feeder 5a, a hydrogen peroxide feeder 5b, a liquid-phase decomposer 6, a cation resin tank 7, a mixed bed resin tank 8, a mixer 9 and an ozonizer 10. The mixed bed resin tank 8 is filled with mixture of cation resins and anion resins. The decontamination liquid 1a is driven by the circulation pump 3 through the circulation loop 2 and the radioactive component 30. When the oxide film on the surface of the radioactive component 30 is reduced and dissolved, reducing aqueous solution mixture including formic acid and oxalic acid is fed to the circulation loop 2 through the decontamination agent feeder 5a. The iron ions dissolved into the reducing decontamination liquid is separated and removed by the cation resin tank 7. After the reducing-decontaminating step, the reducing decontamination liquid is decomposed into carbon dioxide and water. The decomposition is conducted either by injecting ozone gas from the ozonizer 10 to the circulation loop 2 via the mixer 9, or by feeding hydrogen peroxide from the hydrogen peroxide feeder 5b. The metal ions dissolved in the decontamination liquid 1a are removed by the cation resin tank 7. If ozone or hydrogen peroxide is remained when the decontamination liquid 1a is passed through the cation resin tank 7, ultraviolet ray is irradiated at the liquid-phase decomposer 6. Thus, the ozone is decomposed into oxygen, and the hydrogen peroxide is dissolved into hydrogen and oxygen. When the oxide film on the surface of the radioactive component 30 is oxidized and dissolved, ozone gas is injected from the ozonizer 10 to the mixer 9 to generate ozone water, and the ozone water is injected into the decontamination liquid 1a in the circulation loop 2. The decontamination liquid remained in the system after the decontamination process is cleaned by passing through the mixed bed resin tank 8. Although oxide film formed on stainless steel surface can be dissolved and removed with only formic acid accompanied by oxidation treatment, iron oxide can be hardly dissolved with only formic acid. In the present embodiment, oxalic acid is added to the formic acid in order to dissolve the iron oxide. The mole fraction of formic acid is 0.9 or more in the decontamination liquid of the mixture aqueous solution of formic acid and oxalic acid. Formic acid can be decomposed in a short time with only hydrogen peroxide, as described below. Besides, oxalic acid in low concentration can be decomposed in a short time with ozone, permanganic acid or potassium permanganate. Therefore, time for decontamination treatment can be drastically shortened. Ozone, permanganic acid or permanganate (potassium permanganate, for example) can be used as an oxidizer for oxidizing the surface of the radioactive component. Using such oxidizer with formic acid can enhance dissolving-removing rate of the oxide film. Since equilibrium constants of the complex forming reactions of ions of Fe2+ and Fe3+ with formic acid are small, both types of ions can be adsorbed and separated with cation resins. Therefore, a device for reducing Fe3+ ions into Fe2+ ions is not required which is required when oxalic acid is used. Although formic acid can be decomposed with hydrogen peroxide in a short time, oxalic acid can hardly be decomposed with only hydrogen peroxide. The oxalic acid, which is remained after formic acid is decomposed, is decomposed with ozone, permanganic acid and potassium permanganate which are used in oxidation treatment. Since the mole fraction of oxalic acid is 0.1 or less, the oxalic acid can be decomposed in a short time. Now, test results are explained confirming the oxide film dissolution performance of the chemical decontamination method of the first embodiment according to the present invention shown in FIG. 1. The oxide film dissolution tests were conducted with stainless steel (Japanese Industrial Standard SUS 304) test pieces covered with oxide films for 3,000 hours. The oxide films had been formed in water under a condition simulating water in the primary system in a boiling water nuclear power station. FIG. 2 shows the first test results. The ordinate axis represents weight reduction of the oxide films, while the abscissa axis represents formic acid concentration. The blank circles (◯) represent the results obtained by treating with formic acid aqueous solution after treating with ozone aqueous solution. The blank triangles (Δ) represent the results obtained by treating with formic acid aqueous solution after treating with permanganic acid aqueous solution. The blank inverted triangles (∇) represent the results obtained by treating with oxalic acid aqueous solution after treating with ozone aqueous solution, as prior-art examples for comparison. The blank squares (□) represent the results obtained by treating with only formic acid aqueous solution, as other prior-art examples for comparison. The ozone treatment was conducted under a condition of a concentration of 5 ppm, a temperature of 80 degrees Centigrade and a submerging time of 2 hours. The permanganic acid treatment was conducted under a condition of a concentration of 300 ppm, a temperature of 95 degrees Centigrade and submerging time of 2 hours. The formic acid treatment was conducted under a condition of a concentration of 100–50,000 ppm (2.2–110 m mol L−1), a temperature of 95 degrees Centigrade and a submerging time of 1 hour. The oxalic acid treatment was conducted under a condition of a concentration of 2,000 ppm (22 m mol L−1), a temperature of 95 degrees Centigrade and a submerging time of 1 hour. The oxide film was hardly removed by only formic acid (a concentration of 2,000 ppm or 43 m mol L−1) treatment as shown in the graph. On the other hand, in the process with both ozone treatment and formic acid treatment of this embodiment according to the present invention, the oxide was removed more by increased concentration of formic acid. The rate of removal was constant with 1,000 ppm (22 m mol L−1) or more of the formic acid concentration. When the rate of dissolution of the cases with 1,000 ppm (22 m mol L−1) or more of the formic acid are compared, the cases of the present embodiment had about 5 times of the dissolution of the case with only formic acid. The rate of dissolution was equivalent to the prior-art combination of ozone treatment and oxalic treatment. Also in the combination of permanganic acid treatment and formic acid treatment of the present embodiment, oxide film removing effect was obtained. About 3 times of the removing rate of the case with only formic acid treatment was obtained, although the dissolution rate was smaller than the case using the ozone treatment. Furthermore, similar effect was obtained in a test where potassium permanganate was chosen as a permanganate. Treatment of potassium permanganate was conducted and subsequently formic acid treatment was conducted. In the treatment of potassium permanganate, the concentration was 300 ppm, the temperature was 95 degrees Centigrade and submergence duration time was an hour. In the formic acid treatment, the concentration was 2,000 ppm (43 m mol L−1), the temperature was 95 degrees Centigrade and submergence was for an hour. According to the present embodiment of the chemical decontamination method described above, ozone, permanganic acid or permanganate are used in oxidation treatment, and mixture of formic acid and oxalic acid is used as decontamination liquid in reduction treatment. Thus, oxide film generated on surface of stainless steel and iron oxide can be effectively removed or dissolved. Since radioactive material is absorbed in the oxide film on the surface of radioactive component, radioactive material can be removed from the radioactive component by dissolving and removing the oxide film. Thus, radiation dosage of the working personnel can be reduced. Only formic acid combined with oxidation treatment can remove the oxide layer on the surface of stainless steel. However, only formic acid can hardly dissolve iron oxide, and decontamination performance would be worse compared to the decontamination liquid of mixture of formic acid and oxalic acid. When permanganic acid or permanganate is used as oxidizer, the ozonizer 10 and the mixer 9 shown in FIG. 1 can be eliminated. Now the fourth test results are explained, which are featured in decomposition of hydrogen peroxide and ozone that are remained after decomposition of the decontamination liquid mixture of formic acid and oxalic acid. Although iron ions and radioactive material which have been dissolved into the decontamination liquid are separated by the ion exchange resins, deterioration of the ion exchange resins due to oxidation can be accelerated, if hydrogen peroxide and ozone are remained in the decontamination liquid. In order to suppress the deterioration, the decontamination liquid is irradiated with ultraviolet ray (h ν), so that hydrogen peroxide and ozone are decomposed into water and oxygen as shown in Equations (4) and (5): Decomposition of hydrogen peroxide:H2O2+hν-->O2+2H++2e− (4) Decomposition of ozone:O3+hν-->O+O2 (5) In order to confirm the reaction described above, tests of decomposing hydrogen peroxide and ozone remained in the decontamination liquid (with formic acid concentration of 10 ppm or less) were conducted. The test results of hydrogen peroxide decomposition are shown in FIG. 3 and the test results of ozone decomposition are shown in FIG. 4. The ultraviolet ray output power was 3 kw/m3. Hydrogen peroxide concentration decreased from the initial value of 20 ppm to 1 ppm in 1.5 hours, and ozone concentration decrease from the initial value of 5.5 ppm to 0.1 ppm in 12 minutes. As discussed above, the hydrogen peroxide and ozone, which remain in the decontamination liquid during or after the decomposition of formic acid, can be decomposed by ultraviolet ray. Therefore, the dissolved metal ions can be separated without decreasing exchange capacity of the ion exchange resins. Thus, generation rate of spent ion exchange resins as secondary waste can be reduced. The liquid-phase decomposer 6 for ultraviolet ray irradiation is used only to secure soundness of the ion exchange resins by decomposing the hydrogen peroxide and ozone which remain in the decontamination liquid. Therefore, if there are no hydrogen peroxide and ozone remained or if separation treatment of dissolved metal ions by the ion exchanger is omitted, the liquid-phase decomposer 6 can be eliminated. It is known that addition of corrosion suppression agent is effective for suppressing corrosion of stainless steel which is in contact with oxidizer of ozone water. The corrosion suppression agent includes carbonic acid, carbonate, hydrogen carbon ate, boric acid, borate, sulfuric acid, sulfate, phosphoric acid, phosphate and hydrogen phosphate. In the embodiment according to the present invention described above, the cited corrosion suppression agents have proved to be effective in suppressing corrosion of stainless steel base material during the oxalic acid decomposition process, because ozone gas is fed during the oxalic acid decomposition process. According to the method and system for chemical decontamination of radioactive component of the present embodiment described above, oxide film including radioactive material generated or attached on the surface of radioactive component is chemically dissolved and decontaminated. The radioactive component to be decontaminated may be constructive part of a facility for handling radioactivity. In this method, the radioactive material is exposed alternately to reducing decontamination liquid of dissolved mixture of mono-carboxylic acid and di-carboxylic acid, and to oxidizing decontamination liquid dissolved with oxidizer. Thus, the radioactive material is effectively removed and decontaminated. The mono-carboxylic acid and di-carboxylic acid may be formic acid and oxalic acid, respectively, for example. The Fe3+ ions, which have eluted into the reducing mixture decontamination liquid, can be separated by the cation resins. Therefore, reducing device or reducing process for reducing Fe3+ ions into Fe2+ ions is not required, which results in cost reduction of the total decontamination system construction. Furthermore, the formic acid in the reducing mixture decontamination liquid can be decomposed by only hydrogen peroxide, and the low concentration oxalic acid can be decomposed by oxidizing aqueous solution in a short time period. Therefore, reducing device or reducing process for generating bivalent iron can be eliminated, which results in further cost reduction of the total decontamination system construction. A second embodiment of a method and a system for chemically decontaminating radio active material according to the present invention are now described with reference to FIGS. 5 through 11. In this embodiment, not only the oxide layer on the surface of the radioactive component but also the base metal of the radioactive component may be dissolved. FIG. 5 shows the second embodiment of the system for chemically decontaminating radioactive material according to the present invention. This system is used for chemically decontaminating spent component which has been replaced by a spare component at a periodic inspection of a nuclear power station. The system includes a decontamination tank 1 for storing decontamination liquid 1a. The system also includes a circulation loop 2 which is connected to the decontamination tank 1 for circulating the decontamination liquid 1a. The circulation loop 2 includes a circulation pump 3, a heater 4, a decontamination agent feeder 5a, a hydrogen peroxide feeder 5b, a liquid-phase decomposer 6, a cation resin tank 7, a mixed bed resin tank 8, a mixer 9 and an ozonizer 10. The mixed bed resin tank 8 is filled with mixture of cation resins and anion resins. The decontamination tank 1 is connected to an exhaust gas blower 12 via a gas-phase decomposer tower 11. In this embodiment, an electric insulating plate 33 is disposed on the bottom of the decontamination tank 1, and a corrosion resistant metal support 34 is positioned on the electric insulating plate 33 in the tank 1. The radioactive component 13 is disposed on the corrosion resistant metal support 34. The cathode of a direct current (DC) power source 35 is connected to the corrosion resistant metal support 34. The anode of the DC power source 35 is connected to an electrode 36, which is submerged in the decontamination liquid 1a in the decontamination tank 1. Now, the sequence of the process for decontaminating radioactive component 13 made from stainless steel using the system shown in FIG. 5 is described. First, the decontamination tank 1 is filled with decontamination liquid 1a, which is demineralized water. The decontamination liquid 1a is circulated in the circulation loop 2 by the circulation pump 3, and is heated up to a stipulated temperature by the heater 4. The ozone water or the decontamination liquid 1a is generated by injecting ozone gas from the ozonizer 10 to the loop 2 via the mixer 9. The chromium oxide (Cr2O3) in the oxide film of the radioactive component (or the component to be decontaminated) 13 is dissolved by the oxidation effect of ozone into the decontamination liquid or the ozone water 1a. This reaction is shown in Equation (6):Cr2O3+3O3+2H2O→2H2CrO4+3O2 (6) The ozone gas generated in the decontamination tank 1 is sucked by the exhaust gas blower 12. Then, the ozone gas is decomposed in the gas-phase decomposer tower 11 and is exhausted through existing exhaust system. Now a method for dissolving the base metal of the radioactive component (or component to be decontaminated) 13. Formic acid and oxalic acid are injected from the decontamination agent feeder 5a, and decontamination liquid 1a of mixture of formic acid and oxalic acid is generated in the decontamination tank 1. The decontamination mixture 1a is driven by the circulation pump 3 to circulate through the circulation loop 2, and is heated up to a stipulated temperature by the heater 4. In this state, electric potential is provided between the corrosion resistant metal support 34 connected to the cathode of the DC power source 35 and the electrode 36 connected to the anode of the DC power source 35. Since the radioactive component 13 of stainless steel is in contact with the corrosion resistant metal support 34, the potential of the component 13 decreases to a corrosion region of stainless steel, and the base metal is dissolved to be decontaminated. If the corrosion resistant metal support 34 were in electric contact with the decontamination tank 1, the decontamination tank 1 and the circulation loop 2, which is in contact with the circulation loop 2, would also be corroded due to lowered potential. In this embodiment, the decontamination tank 1 and the circulation loop 2 would not corrode, because the electric insulating plate 33 is disposed on the bottom of the decontamination tank 1. FIG. 6 shows a polarization characteristic curve of stainless steel in acid. This polarization characteristic curve shows corrosion characteristics of metal material in a solution. The axis of ordinate is electric current in logarithmic scale, while the axis of abscissas is the potential. The polarization characteristic curve shows the current at the potential. A larger current corresponds to a larger corrosion elusion rate and a lower corrosion resistance. As for high corrosion-resistant structural material such as stainless steel or nickel-base alloy, corrosion characteristics changes depending on the potential. The corrosion characteristic curve is divided into an immunity region 20, an active region 21, a passive state region 22, a secondary passive state region 23 and a transpassivity region 24. In the immunity region 20 and the passive state region 22, corrosion rate is low because the current is small. On the other hand, in the active region 21 and the transpassivity region 24, corrosion rate is high because the current is large. In the transpassivity region 24, anode-oxidation dissolution with generation of oxygen occurs. The transpassivity region 24 has been utilized in electrolysis decontamination for simple shaped components such as plates and pipes. In this embodiment according to the present invention, the corrosion potential of the stainless steel is lowered to the active region 21, and dissolution with generation of hydrogen is utilized. If the iron ions eluted from the radioactive component 13 were accumulated in the mixture decontamination liquid 1a, the dissolution reaction of the base metal might be suppressed. Therefore, iron ions are removed by guiding the mixture decontamination liquid 1a through the cation resin tank 7. After the decontamination process, hydrogen peroxide is fed through the hydrogen peroxide feeder 5b to the circulation loop 2, or ozone gas is injected from the ozonizer 10 through the mixer 9 to the circulation loop 2. Thus, the formic acid in the mixture decontamination liquid 1a is decomposed into carbon dioxide and water. FIG. 7 shows the results of tests of dissolving base material of stainless steel (JIS SUS 304) by the decontamination liquid of mixture of formic acid and oxalic acid. A test piece of stainless steel was connected to the cathode of the DC power source in the decontamination liquid of the mixture of formic acid and oxalic acid. The concentrations of formic acid and oxalic acid were 44 m mol L−1 and 3.3 m mol L−1, respectively. A potential was loaded between the test piece and the anode in the decontamination liquid. As for the test conditions, the temperature of the mixture decontamination liquid was maintained a constant value of 95 degrees Centigrade, and the potential of the test piece was changed within the range of −1,000 to −500 mV as represented with blank circles (◯) in FIG. 7. The ordinate axis is dissolution rate of the test piece, while the abscissa axis is potential of the test piece. FIG. 7 also shows other test results for comparison. One result represented with a solid circle (●) shows a result of a test without potential control, and another result represented with a blank triangle (Δ) shows result of a test with potential control in liquid of only oxalic acid aqueous solution with a concentration of 3.3 m mol L−1. Average dissolution rate of the test pieces in a potential range of −1,000 to −500 mV in the mixture decontamination liquid represented by “∘” was 0.6 mg dm−2 h−1, which was equivalent to the case of only oxalic acid presented by “Δ”. On the other hand, in the case of submergence in the mixture decontamination liquid without potential control represented by “●”, there were almost no dissolution. In the tests described above, the radioactive component 13 was connected to the cathode of the DC power source 35, and the potential of the component 13 was lowered to the corrosion region. The test results showed that the base material could be dissolved. The result means that the radioactive material which might have intruded in the base material of the radioactive component 13 would be removed. FIG. 8 shows results of the tests where trivalent iron was separated with the cation exchange resins by changing mole fraction of formic acid in the mixture decontamination liquid. The ordinate axis is concentration ratio (post-test/pre-test ratio) of trivalent iron in the mixture decontamination liquid, while the abscissa axis is mole fraction of formic acid in the mixture decontamination liquid. When the mole fraction of the formic acid was 0.93 or more, all of the trivalent iron was separated by the cation exchange resins. On the other hand, when the mole fraction was 0.91 or less, part of the trivalent iron remained, and the remained trivalent iron concentration increased substantially linearly with decrease of mole fraction. When the decontamination liquid of only oxalic acid, which has been practically used as a chemical decontamination agent, is used, trivalent iron ions form complexes with oxalic acid. Therefore, the trivalent iron ions cannot be separated by a cation exchange resins. In order to separate the trivalent iron ions by a cation exchange resins, the trivalent iron must be reduced into bivalent iron by irradiating ultraviolet ray. When the decontamination mixture of formic acid and oxalic acid is used according to the present invention, the trivalent iron can also be decomposed. When the mol fraction of formic acid in the decontamination mixture liquid is 0.9 or more, almost all trivalent iron can be separated. Thus, by using the decontamination liquid mixture of formic acid and oxalic acid according to the present invention, device and process for reducing trivalent iron can be eliminated. Therefore, decontamination treatment cost can be reduced compared to a case using decontamination liquid of only oxalic acid. FIG. 9 shows the results of the tests of decomposing the decontamination mixture aqueous solution of formic acid and oxalic acid according to the present invention and prior-art aqueous solution of only oxalic acid. The tests included cases of aqueous solution of only oxalic acid of concentration of 22 m mol L−1 which are represented by blank squares (□). The tests also included cases of mixture aqueous solution of formic acid of concentration of 44 m mol L−1 and oxalic acid of concentration of 1.1 m mol L−1, represented by blank triangles (Δ) and blank inverted triangles (∇). The temperature was 90 degrees Centigrade. Iron ions of 0.36 m mol L−1 were dissolved in each aqueous solution. As for decomposing, the formic acid was decomposed by the mixture aqueous solution with hydrogen peroxide (added amount: 1.5 times of equivalent) as shown by blank triangles (Δ), first. Then, the oxalic acid was decomposed by the ozone (O3 generation rate/amount of liquid: 75 g/h/m3) as shown by blank inverted triangles (∇). The aqueous solution of only oxalic acid was decomposed by combination of ultraviolet ray (output power/liquid volume: 3 kw/m3) and hydrogen peroxide (added amount: 1.5 times of equivalent). The ordinate axis of FIG. 9 is ratio of organic carbon concentration to initial value. As for the prior-art test results, the aqueous solution of only oxalic acid was decomposed to an organic carbon concentration of 0.8 m mol/L−1 or less in 10 hours by the combination of hydrogen peroxide and ultraviolet ray. As for the mixture aqueous solution of this embodiment according to the present invention, the formic acid was decomposed by only hydrogen peroxide, while the oxalic acid was not decomposed by only hydrogen peroxide. Then, after the formic acid was decomposed, the oxalic acid was decomposed by the ozone which was also used for oxidation, and the both acids were decomposed to an organic carbon concentration of 0.8 m mol L−1 or less in less than 4 hours in total. Alternatively, the oxalic acid may be decomposed by other oxidizing aqueous solution such as permanganic acid or potassium permanganate. The reason for not decomposing the formic acid by oxidizing aqueous solution was discussed before, in conjunction with the first embodiment. The aqueous solution mixture of formic acid and oxalic acid requires about half time period compared to oxalic acid which has been practically used as decontamination agent. Although decomposition of oxalic acid requires a step for reducing trivalent iron to bivalent iron as explained as background art, decomposition of the aqueous solution mixture does not require a reducing step, which results in lower cost for total decontamination work. FIG. 10 shows results of the tests of dissolving stainless steel (JIS SUS 304) test pieces for confirming effect of removing oxide films formed on the surface of the components to be decontaminated. The test pieces had been provided with oxide surface film by soaking in hot water of 288 degrees Centigrade, simulating properties of the water in the primary system of a boiling water nuclear reactor, for 3,000 hours. As for the test sequence, first, oxidation treatment was conducted by ozone water at a temperature of 80 degrees Centigrade with an ozone concentration of 5 ppm, and the duration time period was 2 hours. Then, the base material was dissolved in the aqueous solution mixture of formic acid and oxalic acid with a potential control. The concentrations of formic acid and oxalic acid were 44 m mol L−1 and 3.3 m mol L−1, respectively—same as in the cases of FIG. 7. The temperature was 95 degrees Centigrade, and the duration time period was 1 hour. The potential was controlled at −500 mV vs Ag—AgCl. FIG. 10 also shows the result of a test with aqueous solution mixture of formic acid and oxalic acid with a potential control without oxidation treatment. The concentrations of formic acid and oxalic acid, the temperature, the duration time period and the potential control were same as in the cases described above. As shown in FIG. 10, the cases with oxidation by ozone water resulted in about three times larger weight reduction compared to the cases with only potential control or without oxidation. Most of the oxide film remained in the cases with only potential control, while most of the oxide film was removed in the cases with potential control and oxidation. When the component to be decontaminated is made from stainless steel, main contents of the oxide film on the surface are iron oxide and chromium oxide, and most of the radioactive material is contained in the oxide film. Chromium oxide is dissolved by oxidizer such as ozone, while iron oxide is dissolved by reduction with organic acid such as formic acid and oxalic acid, as described later referring to FIG. 11. Therefore, it is to be understood from these test results that oxidation by ozone water is effective for removing radioactive material from the component to be decontaminated. Aqueous solution of permanganic acid or permanganate have effect similar to ozone water. FIG. 11 shows test results of measured dissolved iron concentration. Hematite (Fe2O3), which was used for simulating iron oxide in oxide film, was added into the mixture decontamination liquid at 95 degrees Centigrade. The axis of ordinate is dissolution rate in m mol L−1 h−1, while the axis of abscissa is mole fraction of oxalic acid in the mixture decontamination liquid. When the mole fraction is zero, the decontamination liquid contains only formic acid. The horizontal dotted line in FIG. 11 shows the test results of measured dissolved iron concentration when decontamination liquid of only oxalic acid (concentration: 22 m mol/L) was used. The test results showed, hematite was hardly dissolved by only formic acid, but it was dissolved by adding oxalic acid to formic acid. The dissolution rate increased substantially proportionally to the concentration of oxalic acid. When mole fraction of oxalic acid was 0.05 or more, the dissolution rate was over that of decontamination of only oxalic acid. The test results showed that the mixture decontamination liquid can dissolve iron oxide which is the main component of oxide film. Since the dissolution rate of iron oxide heavily affects decontamination performance, the mixture decontamination liquid has a decontamination performance equivalent to or better than the prior-art decontamination liquid of only oxalic acid. The above discussion is now summarized. Even aqueous solution of only formic acid or of only oxalic acid can dissolve base material, if the potential of the base material is lowered to the corrosion region of the stainless steel. However, in case of aqueous solution of only formic acid, the dissolution rate of base material is low, and iron oxide in the oxide film containing radioactive material is hardly dissolved. Since the bivalent iron and trivalent iron ions dissolved in aqueous solution of formic acid, which hardly form complexes with formic acid, can be easily separated by cation exchange resins. On the other hand, in the cases of oxalic acid, which has been practically used as decontamination agent, the dissolution rate of base material is high, and the iron oxide is reduced and dissolved. However, since trivalent iron easily forms complexes with formic acid ions, trivalent iron cannot be separated by cation exchange resins. According to this embodiment of the present invention, by using aqueous solution of mixture of formic acid and oxalic acid, merits of both acid are utilized, while demerits are compensated. By using the mixture decontamination liquid, dissolution rate of stainless steel base material increases, and trivalent iron can be separated. Especially, the separation performance of trivalent iron is enhanced when the mole fraction of formic acid in the mixture decontamination liquid is 0.9 or more. Thus, the device for reducing trivalent iron into bivalent iron can be eliminated which is required when only oxalic acid is used. While formic acid can be decomposed by only hydrogen peroxide in a short time period, oxalic acid can hardly be decomposed by only hydrogen peroxide. Oxalic acid, which remains after formic acid is decomposed, is decomposed by ozone, hydrogen permanganic acid or potassium permanganate. Since the mole fraction of formic acid is 0.9 or more, the decomposition is conducted in a short time period. When chromium oxide is contained in oxide film on the surface of the component to be decontaminated, the radioactive material in the oxide film can hardly removed, because chromium oxide is hardly dissolved by decontamination liquid mixture of formic acid and oxalic acid. In order to enhance decontamination performance, oxidation treatment using ozone, permanganic acid or permanganate is also utilized. Chromium, which has been eluted from the oxide film, is dissolved in the decontamination liquid in a form of hexavalent chromium. Since hexavalent chromium is harmful, it must be made harmless through reduction into trivalent chromium. Formic acid is added to the decontamination liquid so that the pH of the liquid becomes 3 or less, and hexavalent chromium is reduced into trivalent chromium by hydrogen peroxide. Since formic acid can be easily decomposed into carbon dioxide and water by hydrogen peroxide, generation rate of secondary waste accompanied by reduction process can be drastically reduced. Trivalent chromium, bivalent nickel, and bivalent and trivalent iron ions in the decontamination liquid are separated by cation exchange resins. If hydrogen peroxide or ozone is still in the decontamination liquid during the separation process, the ion exchange resins would be oxidized and deteriorate, which would result in decrease in exchange capacity of ion exchange resins and elution of component of the resins into the decontamination liquid. In order to evade such an incident, ultraviolet ray is irradiated on the decontamination liquid so that the hydrogen peroxide and ozone are decomposed. According to this embodiment of the present invention, the radioactive component 13 of stainless steel in the decontamination liquid mixture 1a of formic acid and oxalic acid is connected to the cathode of the DC power source 35. Then, the potential of the radioactive component 13 is lowered to the corrosion region of stainless steel, so that the base metal is dissolved and decontaminated. Thus, corrosion of the decontamination device and resultant failures are prevented. In addition, since the oxide film on the surface of the radioactive component 13 is dissolved and removed by combination with oxidation, dissolution of the base metal is accelerated, and the decontamination rate is enhanced. Furthermore, the device and process for reducing trivalent iron can be eliminated by setting the mole fraction of the formic acid in the decontamination liquid mixture to 0.91 or more. Since the decomposition time period is drastically reduced, total cost for decontamination work is also drastically reduced. Numerous modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that, within the scope of the appended claims, the present invention can be practiced in a manner other than as specifically described herein.
062263420	summary	TECHNICAL FIELD The present invention relates to components of a light-water nuclear reactor. The invention specifically relates to a ceramic device to retain fuel rods therein. BACKGROUND OF THE INVENTION A fuel assembly in a boiling-water nuclear reactor comprises a long tubular container. The container is often made with a rectangular or square cross section and is open at both ends to make possible a continuous flow of coolant through the fuel assembly. The fuel assembly comprises a large number of equally long tubular fuel rods, arranged in parallel in a defined typically symmetrical, pattern. The fuel rods are retained at the top by a top tie plate and at the bottom by a bottom tie plate. To allow optimum coolant optimum flow along the fuel rods, it is important to keep these at a distance from each other and prevent them from bending or vibrating when the reactor is in operation. If the flow of coolant around a fuel rod is prevented, so-called dryout may occur on the surface of the fuel rod, which may result in damage of the fuel rod. To secure the flow of coolant along the fuel rods, a plurality of spacers are distributed longitudinally along the fuel assembly; however, each new spacer contributes to the pressure drop across the fuel assembly. To minimize the risk of dryout to the fuel assembly the flow of coolant is maintained at a fixed margin, the dryout margin, designed to exceed the coolant flow at which dryout occurs under the relevant conditions. A fuel assembly for a pressurized-water nuclear reactor has, in principle, the same construction as a fuel assembly for a boiling-water nuclear reactor except that the fuel rods are not enclosed by any tubular container and that their number is greater. Normally, a fuel assembly comprises components for retaining the elongated elements, such as spacers, top tie plate and bottom tie plate. These components are normally made of metallic materials, preferably of zirconium alloys or so-called superalloys based on nickel. The resilient clamping force which the retaining components apply to the fuel rods decreases, relaxes, during operation of the reactor as a consequence of the metallic material mechanically degrading, under the conditions prevailing in the fuel assembly during operation. In addition, corrosion, erosion and abrasion damage arise under conditions which prevail in the fuel assembly during operation of the nuclear reactor. The degradation of the retaining components, as well as the occurrence of abrasion, erosion and corrosion damage, may be predicted. When dimensioning these components, the degradation is taken into consideration by oversizing the thickness of the material of the components. This oversizing of the thickness of the material of the components results in an increase of the pressure drop across the fuel assembly. The object of the present invention is therefore to provide a device for retaining elongated elements such as fuel rods in a fuel assembly for a light-water nuclear reactor. The device makes possible an increased operating margin, that is, a margin with respect to dryout as a consequence of too low a coolant flow such that the components included in the device exhibit both improved mechanical properties, including a reduced relaxation of the clamping force which is applied to the elongated elements, and an improved resistance to damage caused by corrosion, erosion and/or abrasion. SUMMARY OF THE INVENTIONS According to one aspect of the present invention, a fuel assembly comprising a device for retaining elongated elements, such as fuel rods, is provided. The retaining element of this invention retains its mechanical rigidity under the conditions of heat, fluid flow and other environmental conditions that occur during the operation of a nuclear reactor. A fuel assembly according to the invention comprises components, which are completely or partially made of a ceramic material, such as zirconium dioxide. Preferably, a two-phase zirconium dioxide is used, based on material where the high-temperature shape of the zirconium dioxide has been stabilized by the addition of a stabilizing dopant, such as an oxide of magnesium, calcium, yttrium, or a mixture of two or more of these oxides, that is, a so-called partially stabilized zirconium dioxide. These components are preferably formed in such a way that the ceramic part of a component constitutes a mechanically self-supporting structure. The good mechanical properties and good resistance against erosion, corrosion and abrasion of the ceramic parts of the components which are included in a device according to the invention are ensured by manufacturing ceramic bodies with low porosity and with few and controlled defects by pressing and sintering, starting from a ceramic powder. Especially advantageous is the internal stress state which exists in a ceramic body of a partially stabilized zirconium dioxide. One advantage of the enhanced resistance to corrosion, erosion or abrasion of the components included in the device is that the contamination of the reactor water by radioactive corrosion products is prevented. The radioactive corrosion products are thus prevented from being deposited in the circulation system for the reactor water and from there emitting radioactive radiation, against which the personnel have to protect themselves in connection with service work in this circulation system. According to the invention, forming at least one mechanically supporting part of the components, included in a fuel assembly, for retaining the elongated elements such as spacers, bottom tie plate and top tie plate in a ceramic material, the thickness of the material of this component may be considerably reduced. In addition, the risks of degradation of the mechanical properties of the components as a result of creeping and/or as a result of damage caused by erosion, corrosion and/or abrasion are minimized. The reduced thickness of the material also results in a reduction of the pressure drop across a fuel assembly which may be utilized for arranging more spacers in the fuel assembly. This results in a stabilization of the fuel assembly and the flow of coolant through the same, thus attaining the object of the invention, that is, to increase the dryout margin. By increasing the dryout margin, the total cost of the fuel cycle is reduced.
06295332&	claims	1. A method of improving x-ray lithography in the sub 100 nm range to create high quality semiconductor devices, for use in the manufacturing of commercial and military semiconductor devices used in phased array radar, missile seeking devices, direct broadcast satellite television receivers, wide band wireless systems, global positioning satellite receivers and cellular telephones, and other equipment said method comprising the steps of: providing for the use and development of horizontal beams from a synchrotron or point source of x-ray beams; preparing of submicrometer, transverse horizontal and vertical stepper stages and frames; providing a stepper base frame for the proper housing and mating of the x-ray beam; minimizing the effects of temperature and airflow control by means of an environmental chamber; transporting, handling and prealigning wafers and other similar items for tight process control; improving the control and sensing of positional accuracy through the use of differential variable reluctance transducers; controlling the continuous gap and all six degrees of freedom of the wafer being treated with a multiple variable stage control; incorporating alignment systems using unambiguous targets to provide data to align one level to the next; using beam transport, shaping or shaping devices to include x-ray point sources; using an inline collimator or concentrator for collimating or concentrating the x-ray beams; and imaging the mask pattern at the precise moment for optimum effectiveness. said using and developing of horizontal beams from a synchrotron or point source of x-ray beams step comprises the use of a beamline in parallel with the z axis. said preparing of submicrometer, transverse horizontal and vertical stepper stages and frames step comprises providing a light weight, honeycomb structure; said preparing of submicrometer, transverse horizontal and vertical stepper stages and frames step further comprises providing a air or gaseous bearing; said preparing of submicrometer, transverse horizontal and vertical stepper stages and frames step further comprises providing vacuum clamping and mating surfaces; said preparing of submicrometer, transverse horizontal and vertical stepper stages and frames step further comprises providing active weight compensation; said preparing of submicrometer, transverse horizontal and vertical stepper stages and frames step further comprises linear actuators; and said preparing of submicrometer, transverse horizontal and vertical stepper stages and frames step further comprises a fine alignment flexure stage of transverse horizontal and vertical nanometer stages. said providing a light weight, honeycomb structure step comprises the use of at least one composite material. said providing a stepper base frame for the proper housing and mating of the x-ray beam step comprises providing beam alignment and vibration insulation techniques when connecting the stationary x-ray synchrotron or point source. said minimizing the effects of temperature and airflow control by means of an environmental chamber step comprises controlling the temperature and humidity; and said minimizing the effects of temperature and airflow control by means of an environmental chamber step further comprises minimizing particle molecular contamination. said transporting handling and prealigning wafers and other similar items for tight process control step comprises using a cluster like environment in the coating, pre-baking, aligning and exposing, post baking and quality control processes. said improving the control and sensing of positional accuracy through the use of differential variable reluctance transducers step comprises providing positional feedback of the six degrees of freedom alignment stage. said controlling the continuous gap and all six degrees of freedom of the wafer being treated with a multiple variable stage control step comprises using a device having a cross coupled gantry design. said incorporating alignment systems using unambiguous targets to provide data to align one level to the next level step comprises using multiple bright field optical microscopes in order to provide x, y and z, magnification and rotational data; and said incorporating alignment systems using unambiguous targets to provide data to align one level to the next level step further comprises using an additional imaging broad band interferometer alignment system for providing precise alignment of wafer levels and gap controls during x-ray exposure and imaging. 2. A method of improving x-ray lithography in the sub 100 nm range to create high quality semiconductor devices, according to claim 1, wherein: 3. A method of improving x-ray lithography in the sub 100 nm range to create high quality semiconductor devices, according to claim 1, wherein: 4. A method of improving x-ray lithography in the sub 100 nm range to create high quality semiconductor devices, according to claim 3, wherein: 5. A method of improving x-ray lithography in the sub 100 nm range to create high quality semiconductor devices, according to claim 1, wherein: 6. A method of improving x-ray lithography in the sub 100 nm range to create high quality semiconductor devices, according to claim 1, wherein: 7. A method of improving x-ray lithography in the sub 100 nm range to create high quality semiconductor devices, according to claim 1, wherein: 8. A method of improving x-ray lithography in the sub 100 nm range to create high quality semiconductor devices, according to claim 1, wherein: 9. A method of improving x-ray lithography in the sub 100 nm range to create high quality semiconductor devices, according to claim 1, wherein; 10. A method of improving x-ray lithography in the sub 100 nm range to create high quality semiconductor devices, according to claim 1, wherein:
	description	The present invention relates to a cabin structure of a manned vehicle for special environment use that can be driven and operated safely by a driver or operator in an environment where radiation, radioactive or other harmful substances (hereinafter referred to collectively as “special substances”) that adversely affect human health are present (hereinafter referred to as “special environments”), and a technique that allows a vehicle usable in a normal environment to be modified into a manned vehicle for special environment use. Examples of a cabin structure of a manned vehicle used in special environments and a manned vehicle for special environment use include a driver cab structure of a transport apparatus for transporting radiation shielding members and this transport apparatus (see, for example, Patent Document 1), and a vehicle interior structure of a vehicle (car) with a retrofitted radiation protection device and this vehicle (see, for example, Patent Document 2). According to FIG. 2 of Patent Document 1, the transport apparatus 5 is configured to run on continuous tracks 8, with an operator cab 9 surrounded by radiation shield plates provided on the continuous tracks 8. According to FIG. 1 and FIG. 2 of Patent Document 2, the vehicle body 1 has a windshield part 2a covered by a first shielding member 3 and side parts 4 covered by second shielding members 20. Patent Document 1: Japanese Patent Application Laid-open No. 2001-289990 Patent Document 2: Japanese Patent No. 4268162 Patent Document 1 does not describe in detail the structure of attaching the operator cab 9 on the continuous tracks 8. Substantial alteration may be needed if the shielding capabilities of the operator cab 9 are to be changed in accordance with the level of radiation exposure in the environment, which will increase the cost. According to Patent Document 2, shielding members are attached to a common vehicle (car), but it would be difficult to cover the entire vehicle completely with shielding members and to increase the shielding capabilities in this way. An object of the present invention is to enable easy alteration of a vehicle that can be used in a normal environment into a manned vehicle for special environment use, and to provide a vehicle that has sufficient ability to block special substances, and a cabin structure of this vehicle. To achieve the object, the present invention provides a cabin structure of a manned vehicle for special environment use, the structure being configured such that a cabin is mounted on a vehicle body having at least an engine and a vehicle moving mechanism driven by the engine, this cabin storing an operation terminal for operating the engine and the vehicle moving mechanism, and having a space for accommodating an operator who operates the operation terminal or an occupant, wherein the cabin is formed as a casing body having a protection structure and partitioned and separable from the vehicle body, the casing body has a coupling and fastening part on a bottom side thereof for secure attachment to the vehicle body with restraint at least in planar coordinate directions. According to the present invention, the cabin is partitioned and separable from the vehicle body, so that it is possible to provide a protection structure to the cabin only, and as a consequence, it is easy to alter a vehicle that is usable in a normal environment into a manned vehicle for special environment use. As the protection structure is given only to the cabin, the ability to block special substances need be increased only in a limited area. Characteristically, the casing body has no bottom plate, or has a separable bottom plate, the bottom plate (if any, or a lower end part of the casing body) being secured to the vehicle body, and the coupling and fastening part is provided between the vehicle body and the box-like structure for secure attachment with restraint in the planar coordinate directions. According to the present invention, since the casing body has no bottom plate, or has a separable bottom plate, the casing body is lightweight, and can be readily transported or attached to the vehicle body. Characteristically, the casing body has a monocoque structure of a combination of a plurality of metal plates that can function as shielding masses, and around a hole drilled in the metal plate, a baffle is provided at a position facing an incoming direction of special substances, or a bent path for incoming special substances is formed by one or a plurality of the metal plates, so that the operator or occupant inside the cabin is not directly exposed to the special substances from outside the casing body. According to the present invention, since the casing body has a monocoque structure, its weight is lighter than a casing body formed by using frames. With a baffle or a bent path for incoming special substances provided around the hole in the metal plate, ingress of special substances advancing straight into the cabin can be prevented, whereby the amount of special substances inside the cabin is readily reduced. Characteristically, the casing body has a monocoque structure of a combination of a plurality of metal plates that can function as shielding masses, and a gap portion between adjacent metal plates is formed as a bent path for incoming special substances and formed either by an abutment plate provided at a position facing an incoming direction of special substances or by one or a plurality of the metal plates, so that the operator or occupant inside the cabin is not located on a line extending straight from outside air through the gap portion. According to the present invention, a gap portion between adjacent metal plates is formed as a bent path for incoming special substances, formed either by an abutment plate or by one or a plurality of the metal plates, so that ingress of special substances advancing straight into the cabin can be prevented, and the amount of special substances inside the cabin is readily reduced. Characteristically, the casing body has surface parts at least on a front side and a rear side in a vehicle moving direction that are shielded by lead glass with front and rear visibility. According to the present invention, the casing body can be shielded from special substances by means of lead glass while visibility is achieved on the front side and the rear side in the vehicle moving direction. Characteristically, an opening having a seal part for seal off from special substances is formed in the bottom plate of the casing body, and a control unit controlling the vehicle body and supplementary equipment by processing signals including a signal obtained by operation of the operation terminal is disposed as the protection structure inside the casing body, while a signal line for transmitting signals processed in the control unit is extended through the opening into the vehicle body. According to the present invention, electronic circuits such as CPU and controllers of hydraulic circuits are prevented from being damaged by special substances or affected by noise and can be used normally. Characteristically, the coupling and fastening part includes fitting parts protruding and recessed in a direction perpendicular to the planar coordinates, the fitting parts fitting to each other to connect the casing body with the vehicle body and restraining the casing body to the vehicle body in three-dimensional directions. According to the present invention, the casing body is three-dimensionally restrained to the vehicle body via the coupling and fastening part, i.e., in the front to back direction, left-right direction, and up and down direction of the vehicle, so that even though it is heavy, the casing body can be firmly supported on the vehicle body. Characteristically, the coupling and fastening part connects the casing body separably to the vehicle body by fastening bolts. According to the present invention, the casing body can be simply separated from or coupled to the coupling and fastening part by fastening bolts. The present invention also provides a manned vehicle for special environment use including a vehicle body having at least an engine and a vehicle moving mechanism driven by the engine, and a cabin storing an operation terminal for operating the engine and the vehicle moving mechanism and accommodating an operator who operates the operation terminal or a occupant, wherein the cabin is formed as a casing body having a protection structure against special substances, and partitioned and separable from the vehicle body, and the casing body is fixed to the vehicle body via a coupling and fastening part with restraint at least in planar coordinate directions. According to the present invention, the cabin is partitioned and separable from the vehicle body, so that it is possible to provide a protection structure to the cabin only, and as a consequence, it is easy to alter a vehicle that is usable in a normal environment into a manned vehicle for special environment use. As the protection structure is given only to the cabin, the ability to block special substances need be increased only in a limited area. Characteristically, the casing body has a box-like structure without a bottom plate or with a separable bottom plate, the bottom plate (if any, or a lower end part of the casing body) being secured to the vehicle body, and the coupling and fastening part is interposed between the vehicle body and the box-like structure for secure attachment with restraint in planar coordinate directions. According to the present invention, since the casing body has no bottom plate, or has a separable bottom plate, the casing body is lightweight, and can be readily transported or attached to the vehicle body. Characteristically, one or a plurality of openings having a seal part for sealing off from special substances is/are formed in the bottom plate of the casing body facing the vehicle body, and a control unit controlling the vehicle body and supplementary equipment by processing signals including a signal obtained by operation of the operation terminal is disposed inside the casing body, while a signal line for transmitting signals processed in the control unit is configured to transmit the signals to the vehicle body through the opening. According to the present invention, electronic circuits such as CPU and controllers of hydraulic circuits are prevented from being damaged by special substances or affected by noise and can be used normally. Characteristically, the casing body has a monocoque structure of a combination of a plurality of metal plates that can function as shielding masses, and a gap portion between adjacent metal plates is formed as a bent path for incoming special substances and formed either by a baffle provided at a position facing an incoming direction of special substances or by one or a plurality of the metal plates, so that the operator or occupant inside the cabin is not located on a line extending straight from outside air through the gap portion. According to the present invention, a gap portion between adjacent metal plates is formed as a bent path for incoming special substances, formed either by an abutment plate or by one or a plurality of metal plates, so that ingress of special substances advancing straight into the cabin can be prevented, and the amount of special substances inside the cabin is readily reduced. Characteristically, the casing body has surface parts at least on a front side and a rear side in a vehicle moving direction that are shielded by lead glass with front and rear visibility. According to the present invention, the casing body can be shielded from special substances by means of lead glass while visibility is achieved on the front side and the rear side in the vehicle moving direction. Characteristically, the casing body has a monocoque structure of a combination of a plurality of metal plates that can function as shielding masses, and around a hole drilled in the metal plate, a baffle is provided at a position facing an incoming direction of special substances, or a bent path for incoming special substances is formed by one or a plurality of the metal plates, so that the operator or occupant inside the cabin is not directly exposed to the special substances from outside the casing body. According to the present invention, since the casing body has a monocoque structure, its weight is lighter than a casing body formed by using frames. With a baffle or a bent path for incoming special substances provided around the hole in the metal plate, ingress of special substances advancing straight into the cabin can be prevented, whereby the amount of special substances inside the cabin is readily reduced. Characteristically, the coupling and fastening part includes a protrusion and a recess protruding and recessed in a direction perpendicular to the planar coordinates. The protrusion and the recess fit to each other, with one them being formed on the casing body and the other one of them being formed on the vehicle body, to restrain the casing body to the vehicle body in three-dimensional directions. According to the present invention, the casing body is three-dimensionally restrained to the vehicle body via the coupling and fastening part, i.e., in the front to back direction, left-right direction, and up and down direction of the vehicle, so that even though it is heavy, the casing body can be firmly supported on the vehicle body. Characteristically, the vehicle body according to claim 1 is a body of an industrial vehicle having an engine, a vehicle moving mechanism driven by the engine, and a work end driven by operation of the operation terminal in the cabin, and a signal from the operation terminal is transmitted via a signal tube or a signal line directly through the opening(s) to the vehicle body, or transmitted to the vehicle body through the opening(s) via the signal line for transmitting signals processed in the control unit disposed inside the casing body. According to the present invention, electronic circuits such as CPU and controllers of hydraulic circuits are prevented from being damaged by special substances or affected by noise and can be used normally. As described above, according to the present invention, the cabin is partitioned and separable from the vehicle body, so that it is possible to provide a radiation protection structure to the cabin only, and as a consequence, it is easy to alter a vehicle that is usable in a normal environment with no risk of exposure to special substances into a manned vehicle for special environment use. As the cabin only is provided with a protection structure, the ability to block special substances need be increased only in a limited area, so that the shielding capabilities of the cabin against special substances can be readily enhanced. The casing body may be configured without a bottom plate to make it lightweight, so that the casing body can be readily transported or attached to the vehicle body. According to the present invention, since the casing body has a monocoque structure, its weight is lighter than a casing body formed by using frames. With a baffle or a bent path for incoming special substances provided around the hole in the metal plate, ingress of special substances advancing straight into the cabin can be prevented, whereby the amount of special substances inside the cabin is readily reduced. A gap portion between adjacent metal plates is formed as a bent path for incoming special substances, formed either by an abutment plate or by one or a plurality of the metal plates, so that ingress of special substances advancing straight into the cabin can be prevented, and the level of exposure to special substances of the operator or occupant inside the cabin is readily reduced. Further, the casing body can be shielded from special substances by means of lead glass while visibility is achieved on the front side and the rear side in the vehicle moving direction. Furthermore, as the electronic equipment such as the control unit and the like is stored inside the cabin, the electronic circuits such as CPU and controllers of hydraulic circuits are prevented from being damaged by special substances or affected by noise and can be used normally. Moreover, the casing body is three-dimensionally restrained to the vehicle body, i.e., in the front to back direction, left-right direction, and up and down direction of the vehicle, so that even though it is heavy, the casing body can be firmly supported on the vehicle body. By means of bolt fastening between the casing body and the coupling and fastening part, the casing body can be readily separated from or coupled to the coupling and fastening part. The illustrated embodiments of the present invention will be hereinafter described in detail. It should be noted that, unless otherwise particularly specified, the sizes, materials, shapes, and relative arrangement or the like of constituent components described in these embodiments are not intended to limit the scope of this invention. The term “FRONT” with an arrow in each figure represents a vehicle forward direction. The fork lift 10 shown in FIG. 1 and FIG. 2 is an industrial vehicle used for carrying out work in a special environment in particular, such as transporting radioactive waste containers. The structural difference from a common fork lift is that it has a cabin shielded from special substances to protect the driver from exposure to special substances. More specifically, the fork lift 10 is made up of a vehicle body 13 having a pair of left and right front wheels 11 and a pair of left and right rear wheels 12 (reference numerals denoting only those visible on the viewer's side), a cabin 14 attached on top of this vehicle body 13, and a mast device 17 provided to the front of the vehicle body 13 with a pair of left and right forks 16 movable up and down. The vehicle body 13 includes therein an engine 37 (see FIG. 3) that is the power source for driving the front wheels 11, a transmission 38 (see FIG. 3) that changes gears and transfers power from this engine 37, a hydraulic pump as a hydraulic pressure source for moving the forks 16 up and down, a battery for starting the engine and supplying electric power to electronic equipment, and an air conditioner for conditioning the air inside the cabin 14, all these being covered by a vehicle body cover 21. The cabin 14 is formed as a casing body made by a plurality of thick metal plates and lead glass. These thick metal plates and lead glass prevent transmission of special substances into the cabin. On top of the ceiling of the cabin 14 is attached an air purifier 24 that decontaminates and introduces outside air into the cabin 14. The pressure inside the cabin 14 is increased to a level higher than the atmosphere by introducing outside air into the cabin 14, so as to prevent ingress of special substances. The internal pressure of the cabin 14 is maintained at, for example, about 2 atmospheres. The air purifier 24 is installed in the ceiling of the cabin 14 so that the air purifier 24 is positioned farthest possible from the ground, to reduce the effects of special substances from the ground as much as possible. A normal fork lift has a vehicle control unit or engine control unit and various electronic equipment for controlling, for example, the engine, transmission, hydraulic pump, and air conditioner, disposed in the vehicle body 13. The fork lift 10, however, has these control units 43 (see FIG. 3) and necessary electronic equipment 45 (see FIG. 3) located inside the cabin 14 to avoid effects by special substances and to protect them from special substances. The mast device 17 includes a mast 26 attached to a front lower part of the vehicle body 13 to be pivotable, a lift bracket 27 attached to this mast 26 to be movable up and down, the forks 16 attached to this lift bracket 27, and a drive mechanism (not shown) for extending and contracting the mast 26 to move the lift bracket 27 up and down, and tilt cylinders 28 extending between the vehicle body 13 and the mast 26 to tilt the mast 26 forward and backward. The mast 26 consists of an outer mast on the side of the vehicle body 13 and an inner mast attached to this outer mast to be movable up and down. The drive mechanism includes a lift cylinder for moving the inner mast up and down, a chain passing from a stationary part of this lift cylinder to the lift bracket 27, and a roller provided at the top of a movable part of the lift cylinder to support a middle part of the chain as it rotates. As shown in FIG. 3, the cabin 14 is attached on top of the vehicle body 13 such as to be removable, and includes a front window 31, a rear window 32, a left side window 33, and a right side window 34 (see FIG. 4) to obtain front, rear, left side, and right side fields of view, respectively, and a left side door 36 for the driver to get in and out. A door may be provided on the right side instead of the left side door 36 for an operator who operates the operation terminal or an occupant to board or exit the vehicle. As the cabin 14 is removably attached to the vehicle body 13 as described above, the cabin of a commercially available fork lift can readily be replaced with the cabin 14 described above, i.e., the fork lift can readily be altered into a manned vehicle for special environment use. Moreover, as most parts of the common fork lift other than the cabin can be used, the cost for alteration is low. Reference numeral 37 in the drawings denotes the engine that is the power source for driving the left and right front wheels 11, 38 denotes the transmission that changes gears and transfers power from the engine 37, and 39 denotes a power transmission mechanism that transmits the power from the transmission 38 to the left and right front wheels 11. The transmission 38, power transmission mechanism 39, and left and right front wheels 11 form a vehicle moving mechanism 40. Reference numeral 43 denotes the control unit that controls various parts and engine of the vehicle, and 45 denotes electronic equipment other than the control unit. As shown in FIG. 4 and FIG. 5, the vehicle body 13, as the main body of the vehicle, includes a pair of left and right vehicle body frames 41 extending in the front to back direction. A plurality each of support pillars 42 as coupling and fastening parts are welded to these vehicle body frames 41, these support pillars 42 supporting the cabin 14. Reference numeral 51b in the drawings denotes a front surface of a front wall 51, and 52b denotes a rear surface of a rear wall (see FIG. 7). FIG. 6A shows a bottom wall 44 only of the cabin 14 (see FIG. 4 and FIG. 5) that is the bottom plate at the bottom of the cabin, with the upper part of the cabin 14 removed from the illustrations of FIG. 4 and FIG. 5 for the sake of explanation of the bottom wall 44. The bottom wall 44 has a plurality of holes—through holes 44a and 44b—for various piping, harnesses, and wire cables to pass through between inside and outside of the cabin 14. Piping includes, for example, brake piping, and operating oil piping for hydraulic equipment. Harnesses include harnesses for electronic equipment. Wire cables include acceleration pedal cables, shift lever cables for changing gears, and operation lever cables for the forks 16 (see FIG. 1). The bottom wall 44 is removably attached to the respective support pillars 42 each with a plurality of bolts 46 as shown in FIG. 6B and FIG. 6C. Each support pillar 42 is made up of a main body 47 having an L-shaped cross section with an integrally formed upper wall 47a and side wall 47b, and a reinforcement 48 attached perpendicularly to both of the upper wall 47a and the side wall 47b of the main body 47 by welding. As the side walls 47b of the respective support pillars 42 are welded to outer side faces 41a of the vehicle body frames 41, the attachment strength and support strength are high in the width direction of the support pillars 42, i.e., front to back direction of the vehicle (left-right direction in FIG. 6B) relative to the vehicle body frames 41. The support strength in the left-right direction of FIG. 6C is also high, as the reinforcements 48 of the respective support pillars 42 have their width extending in that direction. Moreover, as a plurality of support pillars 42 are attached to the vehicle body frames 41, and as these support pillars 42 support the bottom wall 44, the attachment strength and support strength of the cabin 14 are also high in the up and down direction. As the support structure described above supports the cabin 14 three dimensionally, i.e., in three axis directions, front to back, left to right, and up and down directions of the vehicle, the cabin 14 which is a heavy object can be supported with sufficient support strength. FIG. 7 shows the cabin body 50, with the front window 31, rear window 32, left side window 33, right side window 34, and left side door 36 removed from the cabin 14 shown in FIG. 4 and FIG. 5. The cabin body 50 is made up of the bottom wall 44; a front wall 51 (see FIG. 4), a rear wall 52, a left side wall 53, and a right side wall 54 attached to the front, back, left and right of the bottom wall 44; and an upper wall 56 attached to the tops of these front wall 51, rear wall 52, left side wall 53, and right side wall 54. As shown in FIG. 4, FIG. 5, and FIG. 7, the cabin 14 is a casing body with a box-like structure formed by the cabin body 50, respective windows (front window 31, rear window 32, left side window 33, and right side window 34), and the left side door 36. In FIG. 4, the front wall 51 has an opening (not shown), with a sash 61 attached to the edges of the opening with a plurality of bolts. Lead glass 71 that is special substance shielding glass containing lead oxide is fitted in the sash 61. The sash 61 and the lead glass 71 form the front window 31. In FIG. 5 and FIG. 7, the rear wall 52 has an opening 52a, with a sash 62 attached to the edges of the opening 52a with a plurality of bolts. Lead glass 72 is fitted in the sash 62. The sash 62 and the lead glass 72 form the rear window 32. In FIG. 5 and FIG. 7, the left side wall 53 has openings 53a and 53b, with a sash 63 attached to the edges of the opening 53a with a plurality of bolts. The left side door 36 is hinged to open and close at one end of the rear wall 52 that forms one edge of the opening 53b. Lead glass 73 is fitted in the sash 63. The sash 63 and the lead glass 73 form the left side window 33. In FIG. 4 and FIG. 7, the right side wall 54 has an opening (not shown), with a sash 64 attached to the edges of the opening with a plurality of bolts. Lead glass 74 is fitted in the sash 64. The sash 64 and the lead glass 74 form the right side window 34. The bottom wall 44, front wall 51, rear wall 52, left side wall 53, right side wall 54, upper wall 56, and left side door 36 are all shield plates made of steel plate, lead plate, or a lamination of steel plate and lead plate for shielding special substances, and have a sufficient thickness to shield against the special substances. Similarly to the lead glass 71, the lead glass 72, 73, and 74 is made of glass containing lead oxide that shields against special substances, and all the lead glass 71, 72, 73, and 74 has a sufficient thickness to shield against the special substances. Fillet welding is performed so that the walls are continuous without any gap between them for joining the bottom wall 44 and the left side wall 53, the bottom wall 44 and the right side wall 54 shown in FIG. 8A; the bottom wall 44 and the front wall 51, the bottom wall 44 and the rear wall 52 shown in FIG. 8B; the upper wall 56 and the front wall 51, the upper wall 56 and the rear wall 52 shown in FIG. 9A; the upper wall 56 and the left side wall 53, the upper wall 56 and the right side wall 54 shown in FIG. 9B; the front wall 51 and the left side wall 53, the front wall 51 and the right side wall 54 shown in FIG. 9C; and the rear wall 52 and the left side wall 53, and the rear wall 52 and the right side wall 54 shown in FIG. 9D. As shown in FIG. 10, in the left side wall 53 of the cabin 14 is provided the left side door 36 adjacent on the rear side of the left side window 33 for a driver to get in and out. The left side door 36 is attached to the rear wall 52 to be opened and closed via a plurality of hinges 81. A rotatable lever handle 82 is attached to the left side door 36 which is gripped to open and close the door. Rotating this lever handle 82 locks the left side door 36 to the left side wall 53 or releases the lock. As shown in FIG. 11A, the sash 63 of the left side window 33 consists of a rectangular frame 63a and a flange 63b integrally formed on the outer circumferential surface of the frame 63a. The lead glass 73 is tightly fitted to the inside of the frame 63a. A plurality of bolt holes 63c are formed in the flange 63b, and with bolts 84 threaded into internal threads 53d formed in the left side wall 53, the sash 63 is attached to the left side wall 53. Each hinge 81 consists of a mount side plate 91 attached to the rear wall 52 with a plurality of bolts 86, a door side plate 92 attached to the inner face 36a of the left side door 36 by welding, and a pivot part 93 that rotatably connects these mount side plate 91 and door side plate 92. The lever handle 82 is made up of an outer handle 95 rotatably attached to the left side door 36 and disposed on the outer side of the left side door 36, an inner handle 96 integrally coupled to this outer handle 95, rotatably attached to the left side door 36 and disposed on the inner side of the left side door 36, and a locking piece 97 attached to this inner handle 96. A locking hole 53e is formed in the opening 53b of the left side wall 53 for the locking piece 97 of the lever handle 82 to fit in. Rotating the lever handle 82 to insert the locking piece 97 into the locking hole 53e locks the left side door 36 in a closed position. Reference numeral 98 in the drawings denotes sheet-like sealing members that are bonded to an outer surface of the left side wall 53 and an end face 52d of the rear wall 52 around the edges of the opening 53b in the left side door 36 for providing a seal between the left side door 36 and the left side wall 53, and between the left side door 36 and the rear wall 52 when the left side door 36 is closed, to prevent ingress of special substances from outside into the cabin 14. The sealing members 98 should preferably be made of a material having flexibility such as rubber, urethane and the like. Reference numerals 101, 102, 103, and 104 in FIG. 10 and FIG. 11A denote long shielding blocks as abutment plates arranged on extension lines of possible gaps between the left side door 36 and the left side wall 53, and between the left side door 36 and the rear wall 52 when the left side door 36 is closed, for stopping progression of special substances that advance straight from outside along the extension lines of the gaps toward the gaps to prevent them from entering into the cabin 14. FIG. 11B shows a state in which the left side door 36 is opened as indicated by the arrow, with the lever handle 82 in the state shown in FIG. 11A having been rotated to release the locking piece 97 from the locking hole 53e. The shielding blocks 101, 102, and 103 (FIG. 10 shows 102 and 103) are attached to the left side wall 53, while the shielding block 104 is attached to the left side door 36. By providing the shielding blocks 101, 102, 103, and 104 as described above, the gap formed between the left side door 36 and the shielding blocks 101, 102, and 103, and the gap formed between the left side wall 53 and the left side door 36 form a bent path having an L-shaped cross section (bent path for incoming special substances), so that ingress of special substances is prevented as described above. Similarly, the gap formed between the rear wall 52 and the shielding block 104, and the gap formed between the rear wall 52 and the left side door 36 or hinges 81 form a bent path having an L-shaped cross section (bent path for incoming special substances), so that ingress of special substances is prevented as described above. As shown in FIG. 12, the air purifier 24 (see FIG. 1) has a filter/suction unit 106, which includes an intake port 111 that takes in outside air from below upwards, a filter 112 as a decontamination filter connected to the intake port 111 to filter the special substances in the air as the air passes through, a blower 113 having a suction port 113a connected downstream of the filter 112 to suck in air inside the filter 112, and a seat 114 that supports these filter 112 and blower 113 and attaches them to the ceiling (upper wall 56, see FIG. 1) of the cabin 14 (see FIG. 1). As shown in FIG. 13, the air purifier 24 is made up of the filter/suction unit 106, a duct part 117 connected to this filter/suction unit 106, in particular to a discharge port 113b of the blower 113 forming the filter/suction unit 106 via a rubber hose 116, and a communication hole 118 opened in the upper wall 56 (see FIG. 1) of the cabin 14 to communicate the duct part 117 with the inside of the cabin 14 (see FIG. 10 and FIG. 11A). Reference numeral 112b denotes a discharge port of the filter 112, which is connected to the suction port 113a of the blower 113. Reference numeral 113c is an internal passage of the blower 113. The internal passage 113c partially forms a bent path 115 with the discharge port 112b of the filter 112. The duct part 117 is made up of a duct entrance 121 connected to the rubber hose 116, an entrance shield plate 122 to which the duct entrance 121 is attached, five duct forming blocks 123 to 127 that form a labyrinth structure, and an upper cover 128 (not shown) that covers the entrance shield plate 122 and the duct forming blocks 123 to 127 from above. The lower face of the duct part 117 is directly welded to the upper wall 56 of the cabin 14, so that the duct part 117 and the upper wall 56 of the cabin 14 together form a sealed space as a duct. The operation of the air purifier 24 described above will be explained next. In FIG. 13, when the blower 113 is operated, outside air is sucked in from the intake port 111 as indicated by arrows A, and as the air passes through the filter 112 as indicated by the white arrow B, particles of special substances larger than the opening size of the filter 112 are separated from the air in the filter 112, which then flows from the filter 112 through the blower 113 via the bent path 115 into the duct part 117 as shown by arrow C. A hose 136 may be provided as shown in FIG. 14. This air purifier 131 is made up of the filter/suction unit 106, a duct part 132 arranged near the discharge port 113b of the filter/suction unit 106, in particular on the left side, a communication pipe 134 attached in the upper wall 56 (see FIG. 1) to communicate a labyrinth 133 formed inside the duct part 132 with the inside of the cabin 14 (see FIG. 10 and FIG. 11A), and the hose 136 disposed along the labyrinth 133 and having one end connected to the discharge port 113b and the other end connected to the communication pipe 134. The duct part 132 includes a conduit 137a opened inside for passing the hose 136, an entrance shield plate 137 fitted on the outer circumference of the hose 136, five duct forming blocks 123 to 127 that form a labyrinth structure, and an upper cover 128 (not shown) that covers the entrance shield plate 122 and the duct forming blocks 123 to 127 from above. The lower face of the duct part 132 is directly welded to the upper wall 56 of the cabin 14. FIG. 15 shows another air purifier 141 that may be arranged behind the cabin 14 of the vehicle body 13. This air purifier is made up of the filter/suction unit 106, and an exhaust duct 142 having one end connected to the discharge port 113b of the filter/suction unit 106 and the other end extending through the rear wall 52 of the cabin 14 into the cabin 14. The blower 113 is operated to suck in air behind the fork lift 10 and pressurize the space 146 inside the cabin 14 with the air taken in, as shown by arrow E, from which special substances have been removed. Reference numeral 144 in the drawing denotes a handle as an operation terminal for steering the left and right rear wheels 12 (see FIG. 2), and reference numeral 145 denotes a seat for a driver 167 as an occupant to sit on. In the cabin 14, the control unit 43 is disposed under the seat 145, and the electronic equipment 45 is disposed inside a dash board, to avoid influence of special substances. As shown in FIG. 16, a flange 151 extending forward is welded to the front at the lower end of the front wall 51 that is part of the cabin 14, and a baffle 152 is welded to the front end face 151a of the flange 151. The flange 151 has a plurality of bolt holes 151b. A plurality of internal threads 44d are formed along the edge of the bottom wall 44. Bolts 153 are passed through the bolt holes 151b and screwed into the internal threads 44d. The front wall 51 is thus removably attached to the bottom wall 44 with the plurality of bolts 153. The rear wall 52, left side wall 53, and right side wall 54 are likewise removably attached to the bottom wall 44 with respective sets of bolts. Therefore, as compared to the embodiment shown in FIG. 8B, the upper part of the cabin 14, when removed from the bottom wall 44, is lighter by the weight of the bottom wall 44, so that it is handled more easily. The baffle 152 is disposed perpendicularly to an extension plane of the lower end face 51a of the front wall 51, or perpendicularly to a portion on an extension line of a gap formed between the bottom wall 44 and the front wall 51, so that special substances advancing straight from the front toward the gap between the bottom wall 44 and the front wall 51 as shown by arrow G do not progress as indicated by the dotted line arrow H, and thus ingress of special substances from the gap into the cabin 14 is prevented. As shown in FIG. 17, if holes—the opening 51c—which are formed in a wall of the cabin 14, for example, the front wall 51, is closed by a shield plate 161 with a plurality of bolts 162, baffles 165 may be attached on a front face 51d of the front wall 51 such as to block the pathways along the extension line of the gap 163 formed between the front wall 51 and the shield plate 161 so that special substances will not enter into the cabin 14. Baffles 165 should preferably be attached to the front wall 51 such as to continuously surround the shield plate 161. Special substances advancing along the extension lines of the gap 163 toward the gap 163 as shown by arrows K are stopped by the baffles 165 and do not enter into the cabin 14 through the gap 163 and the opening 51c as indicated by broken line arrows M, so that the driver 167 will be prevented from being exposed to the special substances. There are gaps 168 between attachment flanges 166 that are part of the shield plate 161 and the baffles 165. However, these gaps 168 and the gap 163 together form a bent path 169, which is a bent path for incoming special substances and has an L-shaped cross section, so that they can effectively block the progression of special substances advancing straight from the front of the vehicle into the cabin 14. As shown in FIG. 18A, if a pipe 170 is passed through the through hole 44a in the bottom wall 44, the gap between the through hole 44a and the pipe 171 may be filled with lead wool 171, rubber and the like, and the gaps between the edges at both ends of the through hole 44a and the pipe 171 may be closed with respective baffles 172 and 173, so as to prevent ingress of radioactive substances and special substances into the cabin through the gaps between the through hole 44a and the pipe 171. As shown in FIG. 18B, the baffle 172 consists of a first base plate 176 attached to the bottom wall 44 with bolts 174, and a first overlay plate 177 stacked upon and attached to the first base plate 176. The first base plate 176 has bolt holes 176a for the bolts 174 to pass through, and a cut-out 176b for passing the pipe 170. The first overlay plate 177 has a cut-out 177a for passing the pipe 170. The baffle 173 consists of a second base plate 183 attached to the bottom wall 44 with bolts 174, and a second overlay plate 184 stacked upon and attached to the second base plate 183. The second base plate 183 has bolt holes 183a for the bolts 174 to pass through, and a cut-out 183b for passing the pipe 170. The second overlay plate 184 has a cut-out 184a for passing the pipe 170. As shown in FIG. 18C, the first overlay plate 177 of the baffle 172 and the second overlay plate 184 of the baffle 173 respectively have a cut-out 177a and a cut-out 184a that make tight contact with the pipe 170. The first overlay plate 177 of the baffle 172 and the second base plate 183 of the baffle 173 have overlapping portions 177b and 183c that overlap one upon another. The horizontal gap between the first base plate 176 and the second base plate 183 can therefore be closed from above and below as shown in FIG. 18A and FIG. 18B, so that special substances and radioactive substances advancing upward from below the cabin 14 toward the cabin 14 are blocked and prevented from entering into the space 146 inside the cabin 14. As shown in FIG. 19A, if hydraulic piping 191 or air piping is passed through the opening 44a in the bottom wall 44, a pipe manifold 193 may be attached with a plurality of bolts 192 to the edges of the opening 44a of the bottom wall 44, and hydraulic piping 191 may be installed in this pipe manifold 193. As shown in FIG. 19B, the pipe manifold 193 consists of a manifold body 187 and a flange 188 attached around the sides of the manifold body 187. The flange 188 is attached to the lower face of the bottom wall 44 with a plurality of bolts 192. The manifold body 187 has a first passage 191a, a second passage 191b communicating with the first passage 191a, and a third passage 191c communicating with the second passage 191b. A joint connector 194 is connected to one end of the first passage 191a. One end of the second passage 191b is closed with a plug cap 196. A joint connector 194 is connected to one end of the third passage 191c. Hydraulic piping 191 can be passed through the opening 44a in the bottom wall 44 easily by being connected to respective plug caps 194. Moreover, the gap between the opening 44a and the manifold body 187 can be closed with the flange 188. As shown in FIG. 20A, the opening angle of the left side door 36 is restricted by an opening angle restrictor 201. The opening angle restrictor 201 is made up of a wall side retainer 203 attached to the opening 53b of the left side wall 53, a door side retainer 204 attached to the inner face 36a of the left side door 36, and a chain 205 hanging between the wall side retainer 203 and the door side retainer 204. The left side door 36 can be prevented from being completely shut, by means of a hinge 207. The hinge 207 has a fixed part 211 attached to the edge of the opening 53b of the left side wall 53, and a movable part 213 supported on the fixed part 211 such as to be pivotable up and down around a support shaft 212. To fully close the left side door 36, the movable part 213 is turned down to retract from the open/close range of the left side door 36. To prevent the left side door from being fully closed, the movable part 213 is turned up to be located within the open/close range of the left side door 36. The left side door 36 will then abut on the movable part 213, forming a gap between the left side wall 53 and the left side door 36. There is therefore no worry that a hand or the like will get caught in the door. As shown in FIG. 20B, the opening angle of the left side door 36 is restricted by a stopper 221 as the opening angle restrictor. The stopper 221 is attached to the rear surface 52b of the rear wall 52. When the left side door 36 is opened widely, the tip of the stopper 221 will abut at least one of the left side door 36 and the hinges 81 so that the door does not open any further. The left side door 36 may also be fixed in position by an open/close stopper 225. The open/close stopper 225 is made up of a wall side fixed part 226 attached to the inner face 52c of the rear wall 52, a bar 227 pivotably coupled to the wall side fixed part 226 and having a hooked part 227a at the distal end, and a door side fixed part 228 capable of engaging with the hooked part 227a of the bar 227 and attached to the inner face 36a of the left side door 36. As shown in FIG. 20B, with the hooked part 227a of the bar 227 engaged with the door side fixed part 228, the left side door 36 can be kept opened. To allow the left side door 36 to open or close, the hooked part 227a of the bar 227 is released from the door side fixed part 228, and the bar 227 is pivoted around the wall side fixed part 226 to be stored inside the cabin 14. FIG. 21 shows another cabin structure. The cabin 230 that is part of the fork lift is a casing body with a box-like structure made up of a cabin upper body 231 forming the upper part, a base plate 236 attached to left and right vehicle body frames 41 that are part of the vehicle body 235 as a main body of the fork lift, a plurality of support members 237 as coupling and fastening parts attached on the upper surface of the base plate 236 by welding, and a plurality of bolts (not shown) for fastening the cabin upper body 231 to these support members 237. The cabin upper body 231 is a casing body, but without the bottom wall 44 of the cabin 14 in the embodiment shown in FIG. 5, and with internal threads formed at the lower end of the left side wall 53 and the right side wall 54 (see FIG. 4). That is, the left side wall 53 formed with internal threads is the left side wall 238. The base plate 236 is a shield plate made of steel plate, lead plate, or a lamination of steel plate and lead plate, and has a sufficient thickness to shield against the special substances. The support member 237 consists of a plate having an L-shaped cross section, and a reinforcing plate studding between and attached to two sides of the plate. The L-shaped plate has a plurality of bolt holes for the bolts to pass through. The support members 237 are fastened to the cabin upper body 231 by passing the bolts through the bolt holes of the support members 237 and screwing the bolt tips into the respective internal threads in the left side wall 53 and the right side wall. As the shape of the support members 237 and the fastening structure between the support members 237 and the cabin upper body 231 are similar to the shape of the support pillars 42 and the fastening structure between the support pillars 42 and the cabin 14 shown in FIG. 6A to FIG. 6C, the support structure with the support members 237 described above supports the cabin upper body 231 three dimensionally, i.e., in three axis directions, front to back, left to right, and up and down directions of the vehicle, so that the cabin upper body 231 which is a heavy object can be supported with sufficient support strength. The cabin upper body 231 is a casing body with a box-like structure removably attached to the vehicle body 235 with a plurality of bolts. It is configured lighter as it has no bottom wall, and with fewer number of components, so that handling such as transport or design change are easy, and the cost can be reduced, too. While the casing body is partitioned from the vehicle body and separable therefrom via a coupling and fastening part in the present invention, in an alternative embodiment, the casing body may be directly and separably coupled to the vehicle body. In the embodiment shown in FIG. 21, support members 237 are provided on the base plate 236 of the vehicle body 235. Alternatively, the support members 237 may be welded to a lower end part of the cabin upper body 231, and removably joined to the base plate 236 with bolts. The present invention is preferably applicable to manned vehicles for special environment use.
047972475	abstract	A nuclear reactor having a remotely removable and replaceable thermal insulating shield for the head. Access permitting removal and replacement of the head is thus afforded.. The thermal insulating shield includes a vertical frame of insulating material of polygonal transverse cross section encircling the head. A top panel of insulating material is mounted on the top of the frame pivotal by remote actuation between a horizontal position and a retracted position which may be vertical. In the horizontal position, the panels mate to provide thermal shielding for the head.
	abstract	The process of the present application facilitates the production of electric energy by the deliberate extraction of electrons from atoms and molecules of a gas, vapor, liquid, particulate solid, or any other form of matter that can be passed along the surface or through the electron extraction unit. The extracted electrons are captured, collected and controlled or regulated for distribution as electric energy. It is an energy efficient process for the extraction and capture of electrons for the production of electric energy with positive atomic or molecular ions as byproducts. The product ions can then be confined in a coherent beam or restricted to a magnetic enclosure or by other confinement methods, expelled to the atmosphere, another environment or to ground, or modified into useful molecules. These results are accomplished by the forcible extraction and capture of electrons from the object particles by electrically charged particles in a strong electric field. It is an extremely efficient process, in that, once the primary components are sufficiently charged, thereafter it requires only an occasional replenishment of energy to sustain operation.
	claims	1. A radiation detection apparatus for use in a radiation tomography apparatus, said radiation detection apparatus comprising:a detector element array in which a plurality of detector elements are arranged substantially in a fan-angle direction and in a cone-angle direction of a radiation;a collimator adhesively bonded to a side of said detector element array on which the radiation impinges, and having outer end surfaces on both sides in the cone-angle direction tapered to align with a direction of emission from a radiation source; anda pair of blocks disposed to sandwich said collimator in the cone-angle direction, and having inner end surfaces on both sides in the cone-angle direction tapered to align with said direction of emission. 2. The radiation detection apparatus as recited in claim 1, wherein: said outer end surface in said collimator on either side lies close to said inner end surface in said pair of blocks on either side and separated by a space. 3. The radiation detection apparatus as recited in claim 1, wherein: said outer end surface in said collimator on either side is adjacent to said inner end surface in said pair of blocks on either side with an elastic material interposed therebetween. 4. The radiation detection apparatus as recited in claim 1, wherein:said collimator comprises a plurality of collimator modules arranged in the fan-angle direction, andeach of said plurality of collimator modules has both end surfaces in the cone-angle direction tapered to align with said direction of emission. 5. The radiation detection apparatus as recited in claim 1, wherein:said collimator comprises a plurality of collimator modules arranged in the cone-angle direction, andeach of said plurality of collimator modules has both end surfaces in the cone-angle direction tapered to align with said direction of emission. 6. A radiation detection apparatus for use in a radiation tomography apparatus, said radiation detection apparatus comprising:a detector element array in which a plurality of detector elements are arranged substantially in a fan-angle direction and in a cone-angle direction of a radiation;a collimator adhesively bonded to a side of said detector element array on which the radiation impinges, and having outer end surfaces on both sides in the fan-angle direction tapered to align with a direction of emission from a radiation source; anda pair of blocks disposed to sandwich said collimator in the fan-angle direction, and having inner end surfaces on both sides in the fan-angle direction tapered to align with said direction of emission. 7. The radiation detection apparatus as recited in claim 6, wherein: said outer end surface in said collimator on either side lies close to said inner end surface in said pair of blocks on either side and separated by a space. 8. The radiation detection apparatus as recited in claim 6, wherein: said outer end surface in said collimator on either side is adjacent to said inner end surface in said pair of blocks on either side with an elastic material interposed therebetween. 9. The radiation detection apparatus as recited in any claim 6, wherein:said collimator comprises a plurality of collimator modules arranged in the fan-angle direction, andeach of said plurality of collimator modules has both end surfaces in the fan-angle direction tapered to align with said direction of emission. 10. The radiation detection apparatus as recited in claim 6, wherein: said pair of blocks are included in a support portion for directly or indirectly supporting said detector element array. 11. A radiation tomography apparatus including a radiation detection apparatus, said radiation detection apparatus comprising:a detector element array in which a plurality of detector elements are arranged substantially in a fan-angle direction and in a cone-angle direction of a radiation;a collimator adhesively bonded to a side of said detector element array on which the radiation impinges, and having outer end surfaces on both sides in the cone-angle direction tapered to align with a direction of emission from a radiation source; anda pair of blocks disposed to sandwich said collimator in the cone-angle direction, and having inner end surfaces on both sides in the cone-angle direction tapered to align with said direction of emission. 12. The radiation tomography apparatus as recited in claim 11, wherein:said outer end surface in said collimator on either side lies close to said inner end surface in said pair of blocks on either side and separated by a space. 13. The radiation tomography apparatus as recited in claim 12, wherein:said collimator comprises a plurality of collimator modules arranged in the fan-angle direction, andeach of said plurality of collimator modules has both end surfaces in the cone-angle direction tapered to align with said direction of emission. 14. The radiation tomography apparatus as recited in claim 12, wherein:said collimator comprises a plurality of collimator modules arranged in the cone-angle direction, andeach of said plurality of collimator modules has both end surfaces in the cone-angle direction tapered to align with said direction of emission. 15. The radiation tomography apparatus as recited in claim 11, wherein:said outer end surface in said collimator on either side is adjacent to said inner end surface in said pair of blocks on either side with an elastic material interposed therebetween. 16. The radiation tomography apparatus as recited in claim 15, wherein:said collimator comprises a plurality of collimator modules arranged in the fan-angle direction, andeach of said plurality of collimator modules has both end surfaces in the cone-angle direction tapered to align with said direction of emission. 17. The radiation tomography apparatus as recited in claim 15, wherein:said collimator comprises a plurality of collimator modules arranged in the cone-angle direction, andeach of said plurality of collimator modules has both end surfaces in the cone-angle direction tapered to align with said direction of emission. 18. The radiation tomography apparatus as recited in claim 11, wherein:said collimator comprises a plurality of collimator modules arranged in the fan-angle direction, andeach of said plurality of collimator modules has both end surfaces in the cone-angle direction tapered to align with said direction of emission. 19. The radiation tomography apparatus as recited in claim 18, wherein:said collimator comprises a plurality of collimator modules arranged in the cone-angle direction, andeach of said plurality of collimator modules has both end surfaces in the cone-angle direction tapered to align with said direction of emission. 20. The radiation tomography apparatus as recited in claim 11, wherein:said collimator comprises a plurality of collimator modules arranged in the cone-angle direction, andeach of said plurality of collimator modules has both end surfaces in the cone-angle direction tapered to align with said direction of emission.
053923251	description	DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In accordance with a first preferred embodiment of the invention suitable for installation in pipe 50 of circular cross section, a catalytic recombiner cartridge 52 (see FIGS. 1A and 1B) comprises a first plurality of concentric thin cylindrical shells 54 supported between spacers 56 and 56' and a second plurality of concentric thin cylindrical shells 54' supported between spacers 56' and 56", for example, by spot welding or brazing. The shells are made of catalytic material. Each spacer comprises a number (e.g., four) of planar fins, each fin being welded at one end to a central rod 58 positioned along the axis of the concentric shells. Rod 58 resists torquing of the spacers relative to each other. The fins may be disposed at equiangular intervals, e.g., 90.degree.. The cylindrical shells 54 are formed from thin sheets (e.g., 10-12 mils thick) made of noble metal-doped alloy (e.g., stainless steel doped with at least about 1 wt. % palladium) and provided with a multiplicity of means for generating turbulence. The spacers and central rod may also be made of catalytic material provided with turbulence generating means. The sheets are rolled into a cylindrical shape and then welded (not shown) along the overlapping edges to form a cylindrical shell. The cylindrical shells are then welded (not shown) to the supporting structure, i.e., spacers 56, 56' and 56" welded to central rod 58, to form a cartridge 52 which is installed inside pipe 50 with the surfaces of shells 54 lying generally parallel to the direction of fluid flow. The spacers function to stiffen the concentric shells against flow-induced vibration and to maintain the shells in concentric relationship with channels 64 therebetween. The spacing between adjacent shells is preferably constant, e.g., about 25 mils. Although the preferred embodiment shown in FIG. 1B comprises first and second pluralities of concentric cylindrical shells, it will be appreciated that the invention also encompasses a single plurality of shells supported between a pair of spacers. In accordance with the method of the invention, H.sub.2 gas is injected into the flow at a point immediately upstream of installed cartridge 52. The fluid flowing through pipe 50 should be H.sub.2 -enriched to provide an adequate supply of H.sub.2 for the catalytic recombination of water at the surfaces of shells 54. As a result of this catalytic recombination, the concentrations of O.sub.2 and H.sub.2 O.sub.2 in the fluid exiting cartridge 52 will be reduced to a level whereat the ECP is below the SCC threshold value, thereby reducing the susceptibility to SCC of components immediately downstream of the cartridge. In accordance with a second preferred embodiment of the invention suitable for installation in piping of circular or elliptical cross section, a catalytic recombiner cartridge 80 (see FIG. 1C) comprises a thin sheet 74 fabricated into a helix and welded at its inner edge to a central rod 58 which is supported at both ends inside the pipe 50 by a pair of support members, only one (76') of which is shown. The helix is wound tightly around the central rod and then released to spring into place inside the pipe. In addition to being provided with turbulence generating means, such as perforations (not shown), the sheet 74 has hemispherical spacer bumps 78 for maintaining successive turns of the helix with predetermined spacing. In accordance with a third preferred embodiment suitable for installation in piping of rectangular, square or irregular cross section, a catalytic recombiner cartridge 66 (see FIG. 2A) can be formed by welding a plurality of hexagonal units into a honeycomb array. As shown in FIGS. 2B and 2C, each hexagonal unit comprises a hexagonal shell 68 having spacers 72, 72' and 72" which support first and second pluralities of thin planar sheets 70 and 70'. The thin planar sheets 70 and 70' are spot welded or brazed to the shell as well as to the spacers. The thin sheets (e.g., 10-12 mils thick) are made of noble metal-doped alloy (e.g., stainless steel doped with at least about 1 wt. % palladium) and are provided with a multiplicity of means for generating turbulence. The spacing between adjacent sheets is preferably constant, e.g., about 25 mils. Each spacer has four planar fins welded in an X shape, with the outer tips of the fins being welded to four of the six vertices of the hexagonal shell 68, as shown in FIG. 2A. The spacers and the hexagonal shell may also be made of catalytic material provided with turbulence generating means. Although the preferred embodiment shown in FIG. 2B comprises first and second pluralities of parallel planar sheets, it will be appreciated that the invention also encompasses a single plurality of sheets supported between a pair of spacers. The turbulence generating means function to repeatedly interrupt the boundary layer in fluid flowing along the sheet surfaces. Such turbulence generating means are disclosed in a concurrently filed and commonly assigned U.S. patent application entitled "Catalytic Reactor Element", the disclosure of which is incorporated by reference herein. In accordance with the preferred embodiment disclosed therein, each element of the catalytic reactor is a perforated thin sheet of catalytic material having a multiplicity of small holes, preferably circular holes of equal diameter. The holes can be formed by punching and deburring. The holes are distributed over the sheet in a pattern of staggered rows extending transverse to the direction of fluid flow. The distance between the staggered rows is greater than the distance between holes in each row. This arrangement of perforations optimizes the performance of the elements of the catalytic recombiner in accordance with the invention by limiting boundary layer growth and, at the same time, facilitating communication and mixing of the reactants between flow channels, without introducing an excessive pressure drop in the bulk fluid. In particular, the perforations repeatedly break up the fluid boundary layers on the surfaces of the catalytic reactor elements, which layers block diffusion of the reactants to the surface of the catalytic material. Second, the perforations provide turbulent paths which cause fluid in one flow channel to mix with fluid in another flow channel, thereby preventing formation of local zones of reactant depletion. However, the turbulence generating means need not be holes. Dimples and protuberances (e.g., in the shape of hemispheres) can also be distributed over the sheet surfaces in a pattern of staggered rows. Protuberances can also perform the function of spacers. Although dimples and protuberances are less desirable than holes because the former do not provide mixing of fluid between flow channels, the benefits of disrupting the boundary layer would be realized. Recombiner design in accordance with the invention is effected using general principles of mass transfer which are known in the art. The design process involves selection of material and dimensions so that outlet concentration ratio and pressure drop are consistent with required criteria. In addition, size, weight, accessibility, etc. are important aspects of the design. The key points will be illustrated for typical dimensions and for recombination of water from hydrogen and oxygen, although the results are similar for other species. The outlet concentration ratio for a catalytic recombiner cartridge in accordance with the invention is determined by a mass balance across the recombiner, which yields: EQU ln[C/C.sub.o ]=[1-n.pi.d.sub.p.sup.2 /4][4L/D.sub.h ][.alpha.--be.sup.-CRe ]Sc.sup.-0.67 Re .sup.-0.54 where: ##EQU1## and .alpha..apprxeq.0.77; b.apprxeq.0.59; c.apprxeq.1/3570; D.sub.O2 and D.sub.H2 are the diffusion coefficients of O.sub.2 and H.sub.2, respectively; D.sub.h is the mass transfer diameter; .nu. is the fluid kinematic viscosity; V.sub.0 is the bulk fluid velocity; Re and Sc are the Reynolds and Schmidt numbers, respectively; d.sub.i and L are the diameter and length of the cartridge, respectively; N.sub.0 is the number of concentric shells in the cartridge; t is the shell thickness; n is the number of perforations per unit area of element; and d.sub.p is the perforation diameter. An important design consideration is the pressure drop between the inlet and outlet of the cartridge: ##EQU2## where .rho. is the density of the fluid; g.sub.0 is the acceleration due to gravity; and f is a friction factor which is determined semi-empirically. For compact recombiners, an appropriate correlation is: ##EQU3## where 16,000.gtoreq.Re.gtoreq.1,000, b.sub.0 =2, b.sub.1 =6.10.sup.-4, b.sub.2 =-3. 10.sup.-8 and b.sub.3 =7.10.sup.-13. The recombiner void fraction, .epsilon., is given by: ##EQU4## and the coefficient in .function.(Re) accounts for flow-blockage effects. The outlet concentration ratio for a recombiner cartridge made in accordance with the first preferred embodiment is shown in FIG. 3. The cartridge in this case has 33 concentric shells/inch, each shell having 30 holes/inch.sup.2 of diameter 79 mils and a thickness of 12 mils. The mean spacing of the shells is 30 mils, the void fraction is 80%, and the linear density of a 9-inch-diameter assembly is about 3 lb.sub.m /inch. This recombiner design reduces the outlet concentration of oxidizing agents by a factor of 1000 for a length L of 18 inches at a rated flow of 1.8 ft/sec. The graph shows that the length must increase as the flow rate increases in order to maintain a constant outlet concentration. Thus, a 24-inch length is required at a rated flow of 4.3 ft/sec to obtain the same outlet concentration ratio. This can be achieved by placing 6-inch-long cartridges in series in order to accommodate different flow specifications in pipes of the same inside diameter. Pressure drop increases with overall length and flow velocity, as shown in FIG. 4. The magnitude of .DELTA.p is not sensitive to the alignment of cartridges or to details of the perforation design. Form drag is the major contributor to pressure drop in a compact design. The catalytic recombiner cartridges in accordance with the preferred embodiments of the invention can be installed in a BWR of the type depicted in FIG. 5. In such BWRs, feedwater is admitted into a reactor pressure vessel (RPV) 10 via a feedwater inlet 12 and a feedwater sparger 14, which is a ring-shaped pipe having suitable apertures for circumferentially distributing the feedwater inside the RPV. A core spray inlet 11 supplies water to a core spray sparger 15 via core spray line 13. The feedwater from feedwater sparger 14 flows downwardly through the downcomer annulus 16, which is an annular region between RPV 10 and core shroud 18. Water flowing through downcomer annulus 16 then flows to the core lower plenum 24 and into core 20, which comprises numerous fuel assemblies 22 (only two 2.times.2 arrays of which are depicted in FIG. 5). Each fuel assembly is supported at the top by top guide 19 and at the bottom by core plate 21. A mixture of water and steam exits the core and enters core upper plenum 26 under shroud head 28. Core upper plenum 26 provides standoff between the steam-water mixture exiting core 20 and entering vertical standpipes 30, the latter being disposed atop shroud head 28 and in fluid communication with core upper plenum 26. The steam-water mixture flows through standpipes 30 and enters steam separators 32, which are of the axial-flow centrifugal type. The separated liquid water then mixes with feedwater in the mixing plenum 33, which mixture then returns to the core via the downcomer annulus. The steam passes through steam dryers 34 and enters steam dome 36. The steam is withdrawn from the RPV via steam outlet 38. The BWR also includes a coolant recirculation system which provides the forced convection flow through the core needed to achieve the required power density. A portion of the water is sucked from the lower end of the downcomer annulus 16 via recirculation water outlet 43 and forced by a centrifugal recirculation pump (not shown) into jet pump assemblies 42 (only one of which is shown) via recirculation water inlets 45. The BWR has two recirculation pumps, each of which provides the driving flow for a plurality of jet pump assemblies. The pressurized driving water is supplied to each jet pump nozzle 44 via an inlet riser 47, an elbow 48 and an inlet mixer 46 in flow sequence. The catalytic recombiner cartridge in accordance with the preferred embodiments of the invention can be installed at key locations in the reactor, e.g., in the inlet mixers 46, in the recirculation water outlets 43 or in the core spray sparger 15. Each of these are locations with high concentrations of dissolved oxygen and hydrogen peroxide. Preferably, hydrogen gas is injected upstream of the cartridges. If cartridges are installed in the inlet mixers, the recirculation water and reactor vessel downcomer water (normally having high concentrations of dissolved oxygen and hydrogen peroxide) will flow over the recombiner cartridge surfaces and react with a small hydrogen gas addition to the feedwater. Thus, the catalytically reacted water entering the core lower plenum 24 via the jet pump nozzle 44 through the jet pump throat will be very low in dissolved oxidizing agents. Consequently, the ECP is reduced below the SCC threshold, preventing SCC from occurring in this difficult and costly to repair area. In the absence of the recombiner cartridge, the lower plenum components, such as vessel bottom-head penetrations and access-hole covers, would be susceptible to SCC. The catalytic recombiner cartridge of the invention can be installed in a cylindrical pipe using shim rings. In the case where the diameter of the pipe is decreasing in the downstream direction, the cartridge can be installed with a shim ring wedged between the upstream end of the cartridge and the pipe wall. Although the preferred embodiments have been disclosed in the specific context of BWRs, in principle the invention is applicable to any system made of austenitic stainless steels subject to corrosion from low concentrations of dissolved chemical species from diverse sources. In addition, persons of ordinary skill in the art of nuclear reactor engineering will recognize that the geometry of the catalytic recombiner cartridge in accordance with the invention will depend on the specific design of the component in which the recombiner cartridge is to be installed. Moreover, the structure disclosed herein can be made from catalytic material other than water recombination catalyst to form catalytic reactors other than water recombiners. The preferred embodiments have been disclosed for the purpose of illustration only. Variations and modifications of those embodiments will be readily apparent to mechanical engineers of ordinary skill. For example, the cylindrical shells or planar sheets could be supported in a concentric or parallel array respectively by rounded protuberances distributed over the surfaces instead of by welded spacers. In accordance with a further alternative, shells of rectangular or square section could be used in place of the hexagonal shells of the third preferred embodiment. This variation would be especially useful in pipes of rectangular or square section. All such variations and modifications are intended to be encompassed by the claims appended hereto.
	claims	1. A fixed cluster for a pressurized water nuclear reactor core comprising:rods to be inserted into guide tubes of a nuclear fuel assembly; anda support for the rods from which the rods extend in a longitudinal direction the longitudinal direction being orientated vertically downwards when the fixed cluster is arranged on the nuclear fuel assembly;the support including:an upper head having a longitudinal center axis;fins extending radially outwards from the upper head;systems for mounting the rods so as to be distributed on the fins; andat least two elements for abutment against the upper plate of the core, the abutment elements each protruding longitudinally from the respective fins, beyond the mounting systems, in a direction vertically upwards when the fixed cluster is arranged on a nuclear fuel assembly, the abutment elements being arranged radially outwards relative to the adjacent mounting systems,wherein each abutment element is arranged radially outwards relative to all of the rods supported by the respective fin the abutment element protrudes longitudinally from. 2. The cluster according to claim 1 wherein the abutment elements are located at radially outer ends of the fins. 3. The cluster according to claim 1 wherein the abutment elements are arranged angularly about the longitudinal center axis in a regular manner. 4. The cluster according to claim 3 wherein the support includes two abutment elements arranged in a diametrically opposed manner relative to the longitudinal center axis. 5. The cluster according to claim 1 wherein at least one portion of the upper head and the fins are integral. 6. The cluster according to claim 1 wherein the mounting systems include members for receiving upper ends of the rods and nuts which are screwed to the upper ends to fix the rods in receiving members. 7. The cluster according to claim 6 wherein the nuts protrude longitudinally from the members in a direction vertically upwards when the fixed cluster is arranged on the nuclear fuel assembly, and wherein the nuts are arranged at various levels along the longitudinal center axis. 8. The cluster according to claim 6 wherein the upper ends of the rods include shanks which extend through the nuts and are welded to the nuts. 9. The cluster according to claim 1 wherein at least one fin includes a passage for receiving an instrument. 10. A core of a pressurized water nuclear reactor comprising:an upper plate;a lower plate; andnuclear fuel assemblies which are arranged between the upper plate and lower plate, the core further comprising fixed clusters and movable clusters which are arranged on respective nuclear fuel assemblies, the fixed clusters each comprising:rods which are intended to be inserted into guide tubes of the respective nuclear fuel assembly;a support for the rods from which the rods extend in a longitudinal direction, the longitudinal direction being vertically downwards when the fixed cluster is arranged on the respective nuclear fuel assembly; andat least one element for longitudinal abutment against the upper plate of the core of the nuclear reactor;wherein at least one of the fixed clusters is a fixed cluster according to claim 1, the abutment elements of the fixed cluster being in vertical abutment against the upper plate around a water passage hole which is provided in the upper plate above the nuclear fuel assembly on which the fixed cluster is arranged. 11. The core according to claim 10 wherein at least one movable cluster comprises:rods which are intended to be inserted into the guide tubes of the respective nuclear fuel assembly; anda rod support from which the rods extend in a longitudinal direction, the longitudinal direction being vertically downwards when the movable cluster is arranged on the respective nuclear fuel assembly;wherein the shapes of the supports for the fixed cluster and the movable cluster are similar. 12. The core according to claim 11 wherein the fixed cluster and the movable cluster are adjacent. 13. An assembly comprising a nuclear fuel assembly and a fixed cluster which is capable of being arranged on the nuclear fuel assembly wherein the fixed cluster is a fixed cluster according to claim 1. 14. The cluster according to claim 1 wherein the abutment elements do not mount any of the rods on the fins. 15. The cluster according to claim 1 wherein the abutment elements are integral with the respective fins, forming rigid and solid elements.
	claims	1. A method for removing decay heat from a nuclear reactor after shutdown, where said reactor has nuclear fuel rods and a cooling water input connected to deliver water that is supplied to said cooling water input to said fuel rods, comprising:providing a tank of water having an inlet and an outlet,providing a source of compressed gas,said source of compressed gas being connected to said inlet of said tank of water, said outlet of said tank of water being connected to said cooling water input and to said fuel rods of said reactor,allowing said compressed gas to flow into said inlet of said tank of water so that said compressed gas enters said tank and forces said water to leave said outlet of tank and flow to said cooling water input of said nuclear reactor and then to said fuel rods of said nuclear reactor, said compressed gas being the only force that urges said water to said cooling water input and said fuel rods of said nuclear reactor,whereby said compressed gas will force said water to flow into said nuclear reactor and cool said fuel rods to remove said decay heat from said reactor. 2. The method of claim 1 wherein(a) said source of compressed gas is compressed to at least 1000 pounds per square inch, and further including(b) providing a pressure reducing expansion valve to reduce the pressure of said gas to a relatively lower level of compression before it is allowed to flow into said inlet of said tank of water, and(c) conveying the water that said compressed gas forces from said tank of water to provide heat of expansion to said expansion valve to prevent freezing of the environment around said expansion valve before said water flows to said cooling water input of said nuclear reactor. 3. A passive safety method for cooling the fuel rods in a reactor pressure vessel in a nuclear power plant after a shutdown, where said reactor pressure vessel has a cooling water input, comprising:(a) providing a source of compressed gas at a relatively high pressure of at least 1000 pounds per square inch,(b) providing a reservoir of water,(c) conveying a stream of said highly compressed gas from said source to a location separate from said source,(d) expanding said stream of said highly compressed gas at said separate location to a relatively low pressure gas stream, resulting in lowering the temperature of said gas stream due to the expansion of said gas,(e) using said relatively low-pressure gas stream to force said water out of said reservoir in a stream to said separate location, such that said stream of water makes thermal contact with said relatively low pressure gas stream and supplies heat to said relatively low-pressure gas stream to prevent said relatively low-pressure gas stream from freezing the environment at said separate location,(f) conveying said stream of water from said separate location, after it supplies heat to said relatively low-pressure gas stream, to said cooling water input of said reactor pressure vessel of said nuclear power plant so as to cool said fuel rods in said reactor pressure vessel,whereby said low-pressure gas stream will force said stream of water of water to said separate location where it will first raise the temperature of said low-pressure gas stream to prevent freezing and thereafter to said reactor pressure vessel where it will second absorb heat from said fuel rods in said reactor pressure vessel to mitigate overheating thereof. 4. The passive safety method for cooling a reactor pressure vessel of claim 3 wherein:said location separate from said source contains an expansion valve having an input and an output and a heat exchanger having a water input, a water output, and a compressed gas output,said stream of said highly compressed gas is conveyed to said input of said expansion valve,said stream of water is conveyed to said water input of said heat exchanger so that, when water is forced out of said reservoir, it will flow to said water input of said heat exchanger,said expansion valve placed inside or connected to said heat exchanger so that said water flowing through said heat exchanger will transfer heat to said pressure-reducing expansion valve and to said compressed gas entering and leaving said expansion valve so that said compressed gas will not freeze its environment as it leaves said expansion valve,said output of said expansion valve being arranged to pass said expanded gas into said heat exchanger so that said compressed gas will flow through said heat exchanger to said compressed gas output of said heat exchanger,said compressed gas output of said heat exchanger is connected to said reservoir of water so that it will force said water out of said reservoir and to said water input of said heat exchanger,said water output of said heat exchanger being connected to said cooling water input of said reactor pressure vessel. 5. The passive safety method of claim 3 wherein a plurality of reservoirs of water is provided and said relatively low-pressure gas stream is arranged to force said water out of said plurality of reservoirs to said separate location. 6. The passive safety method of claim 3 wherein a plurality of said sources of compressed gas at said relatively high pressure is provided, and a plurality of streams of said highly compressed gas is conveyed from said plurality of reservoirs to said separate location. 7. The passive safety system of claim 3 wherein said source of compressed gas is contained within said reservoir of water and is surrounded by the water in said reservoir of water. 8. The passive safety method of claim 3 wherein said reservoir of cooling water and said source of compressed gas are portable. 9. The passive safety method of claim 8 wherein said reservoir of water and said source of compressed gas are mounted on at least one movable wheeled conveyance. 10. The passive safety method of claim 3 wherein at least one of said reservoir of water and said source of compressed gas is located at a place selected from the group consisting of above ground and underground. 11. The passive safety method of claim 3 wherein said source of compressed gas is a compressed-gas tank which stores said compressed gas at a pressure of at least 1000 pounds per square inch. 12. The passive safety method of claim 3, further including providing a compressed-gas valve arranged to deliver said stream of said highly compressed gas from said compressed gas tank when said valve is opened and to prevent delivery of compressed gas from said compressed gas tank when said valve is closed. 13. The passive safety method of claim 3 wherein a plurality of reservoirs of water are provided, and said relatively low-pressure gas stream is arranged to force said water out of said plurality of reservoirs to said separate location. 14. The passive safety method of claim 5 wherein a plurality of said sources of compressed gas at a relatively high pressure is provided, and a plurality of streams of said highly compressed gas is conveyed from said plurality of water reservoirs to said separate location. 15. A method for removing decay heat from a nuclear reactor after shutdown, said nuclear reactor having a cooling fluid inlet, said method comprising:providing a tank of water having an inlet and an outlet,providing a source of relatively highly compressed gas compressed to at least 1000 pounds per square inch,providing a pressure-reducing gas expansion valve having an inlet and an outlet and a heat exchanger having an inlet and an outlet,said source of highly compressed gas being connected to said inlet of said expansion valve, so that said highly compressed gas will expand to a relatively low pressure and drop in temperature,said outlet of said tank of water being connected to said inlet of said heat exchanger,said outlet of said expansion valve being connected to said inlet of said tank of water,said outlet of said heat exchanger being connected to said cooling fluid inlet of said reactor, andreleasing said highly compressed gas to said expansion valve so that said gas will expand to a relatively low pressure and flow to said tank of water and force said water to flow through said heat exchanger, said heat exchanger being in thermal contact with said expansion valve, so that said water in said heat exchanger will transfer heat to said gas to prevent said gas from freezing its environment, and then flow to said cooling fluid inlet of said reactor to absorb heat from said reactor to prevent overheating thereof. 16. The method of claim 15 wherein said tank of water and said source of compressed gas are buried underground. 17. The method of claim 15 wherein said tank of water and said source of compressed gas are portable. 18. The method of claim 15 wherein said tank of water and said source of compressed gas are mounted on at least one movable wheeled conveyance. 19. The method of claim 18 wherein said wheeled conveyance, said tank of water, and said source of compressed gas are concealed in a trench. 20. The method of claim 18 wherein a plurality of tanks of water and a plurality of sources of highly compressed gas compressed to at least 1000 pounds per square inch are provided and said plurality of tanks of compressed gas are connected to said plurality of tanks of water.
	abstract	Methods, apparatus, devices, and systems for creating, controlling, conducting, and optimizing fusion activities of nuclei. In particular, the present inventions relate to, among other things, fusion activities that are conducted individually or collectively on a very small scale, preferably on the nano-scale or smaller such as pico to femto scales, for the utilization of energy produced from these activities in smaller devices and for aggregation into larger devices.
	claims	1. An ion implant apparatus comprising:a rotary scan assembly having an axis of rotation and a periphery;the rotary scan assembly further having an axial profile about said axis of rotation and extending to said periphery;a plurality of substrate holders distributed about said periphery, said substrate holders arranged to hold respective planar substrates at a common substrate tilt angle to define a total cone angle about said axis of rotation which is less than 60°;and a beam line assembly to provide a beam of ions for implantation in said planar substrates on said substrate holders, said beam line assembly comprising in sequence in an ion beam direction: an ion source, an ion accelerator effective to accelerate ions from said ion source to produce an accelerated beam having a desired implant energy, and a beam bending magnet having a beam inlet to receive said accelerated beam; wherein said ion source, said accelerator and said beam inlet defining a beam acceleration path which is linear from said ion source to said beam inlet of said beam bending magnet;wherein said beam line assembly further includes an analyzer magnet which is located inside said axial profile of said rotary scan assembly;wherein said beam line assembly is arranged to direct said beam in a predetermined ion implant direction along a final beam path, which is at an angle of at least 45° to said axis of rotation; and wherein said planar substrates on said substrate holders successively intercept said final beam path in a travel direction as said rotary scan assembly rotates. 2. Ion implant apparatus as claimed in claim 1, wherein said analyzer magnet is located after said beam acceleration path and is operative to produce an angular separation in said accelerated beam between ions of different mass/charge ratios (m/e). 3. Ion implant apparatus as claimed in claim 1,wherein said analyzer magnet is operative to direct ions having an m/e which is desired for implantation in said predetermined ion implant direction along said final beam path,wherein said implant apparatus further comprises an ion beam dump which is mounted on said rotary scan assembly and forms an annular beam dump region which rotates with said rotary scan assembly, andwherein said analyzer magnet is operative to direct ions having an m/e greater than said desired m/e towards said annular beam dump region. 4. Ion implant apparatus as claimed in claim 1, wherein said final beam path has a total ion drift distance which is less than a diameter of said periphery of said rotary scan assembly. 5. Ion implant apparatus as claimed in claim 1, wherein said planar substrates comprise a crystalline semiconductor material. 6. Ion implant apparatus as claimed in claim 5, wherein said crystalline semiconductor material is silicon. 7. Ion implant apparatus as claimed in claim 1, wherein said beam of ions for implantation comprises H+ ions. 8. An ion implant apparatus comprising:a rotary scan assembly having an axis of rotation and a periphery;a plurality of substrate holders distributed about said periphery, said substrate holders arranged to hold respective planar substrates at a common substrate tilt angle to define a total cone angle about said axis of rotation which is less than 60°;and a beam line assembly to provide a beam of ions for implantation in said planar substrates on said substrate holders, said beam line assembly comprising in sequence in an ion beam direction: an ion source, an ion accelerator effective to accelerate ions from said ion source to produce an accelerated beam having a desired implant energy, and a beam bending magnet having a beam inlet to receive said accelerated beam; wherein said ion source, said accelerator and said beam inlet defining a beam acceleration path which is linear from said ion source to said beam inlet of said beam bending magnet;wherein said beam line assembly further includes an analyzer magnet which is located near said axis of rotation of said rotary scan assembly;wherein said beam line assembly is arranged to direct said beam in a predetermined ion implant direction along a final beam path, which is at an angle of at least 45° to said axis of rotation; andwherein said planar substrates on said substrate holders successively intercept said final beam path in a travel direction as said rotary scan assembly rotates. 9. An ion implant apparatus comprising:a rotary scan assembly having an axis of rotation and a periphery;the rotary scan assembly further having an axial profile about said axis of rotation and extending to said periphery;a plurality of substrate holders distributed about said periphery, said substrate holders arranged to hold respective planar substrates at a common substrate tilt angle to define a total cone angle about said axis of rotation which is less than 60°;and a beam line assembly to provide a beam of ions for implantation in said planar substrates on said substrate holders, said beam line assembly comprising in sequence in an ion beam direction: an ion source, an ion accelerator effective to accelerate ions from said ion source to produce an accelerated beam having a desired implant energy, and a beam bending magnet having a beam inlet to receive said accelerated beam; wherein said ion source, said accelerator and said beam inlet defining a beam acceleration path which is linear from said ion source to said beam inlet of said beam bending magnet;wherein said beam line assembly is physically contained within said axial profile of said rotary scan assembly;wherein said beam line assembly is arranged to direct said beam in a predetermined ion implant direction along a final beam path, which is at an angle of at least 45° to said axis of rotation; andwherein said planar substrates on said substrate holders successively intercept said final beam path in a travel direction as said rotary scan assembly rotates. 10. Ion implant apparatus as claimed in claim 9, wherein said beam line assembly includes an analyzer magnet which is located after said beam acceleration path and is operative to produce an angular separation in said accelerated beam between ions of different mass/charge ratios (m/e). 11. Ion implant apparatus as claimed in claim 9,wherein said beam line assembly includes an analyzer magnet,wherein said analyzer magnet is operative to direct ions having an m/e which is desired for implantation in said predetermined ion implant direction along said final beam path,wherein said implant apparatus further comprises an ion beam dump which is mounted on said rotary scan assembly and forms an annular beam dump region which rotates with said rotary scan assembly, andwherein said analyzer magnet is operative to direct ions having an m/e greater than said desired m/e towards said annular beam dump region. 12. Ion implant apparatus as claimed in claim 9, wherein said beam bending magnet is a beam scanner magnet operative to deflect said accelerated beam at a repetition rate through a range of deflection angles, to produce a scanned beam such that said final beam path is scanned transversely relative to said travel direction of said substrate holders. 13. Ion implant apparatus as claimed in 12, wherein said beam line assembly includes an analyzer magnet which is located to receive said scanned beam from said beam scanner magnet over said range of deflection angles and is operative to produce an angular separation between beam ions of different mass/charge ratios (m/e). 14. Ion implant apparatus as claimed in 13, wherein said analyzer magnet is operative to direct ions having an m/e which is desired for implantation in a collimated scanned beam in said predetermined ion implant direction along said final beam path. 15. Ion implant apparatus as claimed in claim 14, further comprising an ion beam dump mounted on said rotary scan assembly and forming an annular beam dump region which rotates with said rotary scan assembly, wherein said analyzer magnet is operative to direct ions of said accelerated beam having an m/e greater than said desired m/e towards said annular beam dump region. 16. Ion implant apparatus as claimed in claim 9, wherein said final beam path has a total ion drift distance which is less than a diameter of said periphery of said rotary scan assembly. 17. Ion implant apparatus as claimed in claim 9, wherein said acceleration path is aligned with said axis of rotation of said rotary scan assembly. 18. Ion implant apparatus as claimed in claim 9, wherein said planar substrates comprise a crystalline semiconductor material. 19. Ion implant apparatus as claimed in claim 18, wherein said crystalline semiconductor material is silicon. 20. Ion implant apparatus as claimed in claim 9, wherein said beam of ions for implantation comprises H+ ions.
	description	This invention was made with government support under Contract No. DE-AC52-06NA25396 awarded by the U.S. Department of Energy. The government has certain rights in the invention. The present invention relates generally to the production of molybdenum-99 and to recycling uranium after it has been used for production of molybdenum-99. Technetium-99m (“Tc-99m”) is the most commonly used radioisotope in nuclear medicine. Tc-99m is used in approximately two-thirds of all imaging procedures performed in the United States. Tens of millions of diagnostic procedures using Tc-99m are undertaken annually. Tc-99m is a daughter isotope produced from the radioactive decay of molybdenum-99 (“Mo-99”). Mo-99 decays to Tc-99m with a half life of 66 hours. The vast majority of Mo-99 used in nuclear medicine in the U.S. is produced in aging foreign reactors. Many of these reactors still use solid highly enriched uranium (“HEU”) targets to produce the Mo-99. HEU has a concentration of uranium-235 (“U-235”) of greater than 20%. Maintenance and repair shutdowns of these reactors have disrupted the supply of Mo-99 to the U.S. and to most of the rest of the world. The relatively short half-life of the parent radioisotope Mo-99 prohibits the build-up of reserves. One of the major producers, The National Research Reactor in Canada, will cease production in 2016. An alternative strategy for providing Mo-99 is based upon the use of low enriched uranium (LEU), which presents a much lower nuclear proliferation risk than HEU. LEU has a concentration of U-235 of less than 20%, and many international Mo-99 producers are converting from HEU to LEU solid targets for Mo-99 production. Several of the technologies currently being considered for the domestic supply of Mo-99 are based on the fission of U-235 in mildly acidic solutions of LEU, including the Aqueous Homogenous Reactor concept and an Accelerator-based concept which provides an external source of neutrons. Only a small fraction of the U-235 present in the acidic solution will undergo fission, as is also the case with solid target irradiation. Fission of U-235 generates a variety of fission products, one of which is Mo-99. The uranium in the mildly acidic solution is in the +VI oxidation state and in the chemical form of the uranyl di-oxo di-cation (UO22+). Some form of enriched uranium (HEU and/or LEU) is used for the production of Mo-99. After the fission process, the remaining uranium is typically discarded along with other fission products as waste. Recycling the uranium for additional production of Mo-99 would minimize the waste while maximizing the utilization of the uranium. Therefore, an object of the present invention is to provide a process for recycling uranium after it has been used for the production of Mo-99. Another object is to provide a process for producing Mo-99 using recycled uranium. The embodiments for recovering uranium apply to recovering all isotopic ratios of uranium, including low-enriched uranium (LEU) as well as highly-enriched uranium (HEU). Enriched uranium refers to uranium enriched in isotope U-235. A process for recycling irradiated uranium that has been used for the production of Mo-99 involves providing an aqueous solution comprising uranyl nitrate and nitric acid. The uranyl nitrate comprises uranium, and inducing fission of U-235 in the uranium produces soluble fission products, with the soluble fission products including Mo-99. Thereafter, conditioning the solution promotes the formation of crystals that comprise uranyl nitrate hydrates, and a supernatant that comprises the soluble fission products which includes Mo-99. The crystals will then be separated from the supernatant. In an embodiment, a second aqueous solution is prepared from the crystals. The second aqueous solution comprises uranyl nitrate and nitric acid. After conditioning the second aqueous solution to a suitable acidity and uranium concentration, it is irradiated, inducing fission of U-235 in the uranium that produces soluble fission products, with the soluble fission products including Mo-99. Thereafter, conditioning this second solution promotes a second crystallization, forming crystals that comprise uranyl nitrate hydrates, and forming a supernatant that comprises the soluble fission products which includes Mo-99. The crystals from the second crystallization will then be separated from the second supernatant. In yet another embodiment, a third aqueous solution is prepared from the crystals from the second crystallization. The third aqueous solution comprises uranyl nitrate and nitric acid. After conditioning the third aqueous solution to a suitable acidity and uranium concentration, it is irradiated, inducing fission of U-235 in the uranium that produces soluble fission products, with the soluble fission products including Mo-99. Thereafter, conditioning this second solution promotes a second crystallization, forming crystals that comprise uranyl nitrate hydrates, and forming a supernatant that comprises the soluble fission products which includes Mo-99. The crystals from the third crystallization will then be separated from the third supernatant. Thus, embodiment processes for the recycle of uranium can be repeated multiple times for the production of multiple batches of Mo-99 from the same repeatedly-recycled uranium. After each recycle, a small fraction of less than 10 percent of the original uranium content will be lost during processing. This loss can be made up using a fresh LEU uranyl nitrate aqueous solution and nitric acid and/or recovered uranium from the supernatant solution, after recovery of the Mo-99 by applying the crystallization process. Another embodiment process for the recycle of uranium involves providing an irradiated solid target comprising uranium, irradiating the target to produce fission products comprising Mo-99, and thereafter forming an aqueous acidic solution comprising uranium from the target. The nitric acid and uranium concentrations can be adjusted to concentrations suitable for inducing the formation of crystals of uranyl nitrate hydrates and a supernatant. The crystals can then be separated from the supernatant, thereby recovering uranium that has been used for the production of Mo-99. An embodiment process relates to recovery of uranium that has been used for the production of Mo-99 generated from the fission of U-235. Mo-99 undergoes radioactive decay to Tc-99m, the most widely used radioisotope in nuclear medicine. Recovery of the uranium allows for continued use of the parent radioisotope (U-235) to produce Mo-99, which can decay to generate Tc-99m. Recovery of uranium also minimizes waste by allowing for continued use of the same uranium for the continued production of Mo-99. An embodiment process for recycling uranium that has been used for the production of Mo-99 includes providing an aqueous solution comprising uranyl nitrate and nitric acid, irradiating the solution to produce soluble fission products that include Mo-99. Thereafter adjusting the nitric acid and uranium concentration to concentrations suitable for inducing the formation of crystals of uranyl nitrate hydrates, and a supernatant (i.e., the liquid phase that remains). The crystals may be separated from the supernatant and recycled for the production of additional Mo-99. It should be understood that uranium includes both LEU (uranium having less than 20% of the U-235 isotope), and also HEU (uranium having greater than 20% of the U-235 isotope). Thus, an embodiment of the disclosed process may be used for recovery of either LEU or HEU. In an embodiment, recovery of uranium involves crystallization of uranium compounds from a previously irradiated solution of uranium having a concentration of uranium in a range of from 80 gU/L to 310 gU/L (gU/L means grams of uranium per liter of solution). An embodiment process involves irradiation of a solution that includes uranium in the form of soluble uranyl nitrate in a dilute nitric acid solution. The dilute nitric acid solution has a solution acidity of from about 0.01 M to about 0.5 M (moles/liter). One of the fission products is a soluble species of Mo-99. Some non-limiting species include soluble species that comprise molybdenum in the +VI oxidation state. Examples include H2MoO4, HMoO4− and/or MoO42−. After the irradiation, the resulting solution is evaporated under vacuum and/or through heating, and afterward is acidified with a suitable amount of nitric acid to yield a solution concentration of nitric acid of from about 4M to about 8M, and a uranium concentration of from about 350 gU/L to about 650 gU/L; the temperature of this solution may be raised to ensure that all the uranium remains in solution. This solution is then evaporated under reduced pressure and/or cooled in order to promote conditions suitable for the formation of crystals of uranyl nitrate hydrates from the solution. An example of such a uranyl nitrate hydrate is UO2(NO3)2.6H2O. The crystals are then separated from the supernatant that remains and can be washed with nitric acid. Nitric acid can be removed from the supernatant by evaporation under reduced pressure and/or by heating. Water, and nitric acid if needed, can be added to yield a concentration of nitric acid of from about 0.01 to about 0.2 M and a uranium concentration of from about 10 gU/L to about 70 gU/L. Removal of excess nitric acid from the supernatant facilitates recovery of Mo-99 using a column of adsorbent such as alumina. Recovery of the crystalline uranyl nitrate hydrates provides a means for recovery of uranium for recycle for additional irradiation to promote fission of U-235 to generate additional Mo-99. For recycling, the crystals will be dissolved in water to form a solution, and the solution will be conditioned by evaporation under reduced pressure and/or heating. The solution conditioning process removes nitric acid. The addition of water, and nitric acid if needed, will then result in a solution with a uranium concentration of between about 80 gU/L to 310 gU/L and solution acidity of between about 0.01 to 0.5 M. Only a small fraction of the U-235 component of the uranium undergoes fission during irradiation. Therefore, recycling of uranium according to the present process minimizes the generation of hazardous waste while enabling reuse of uranium for generating Mo-99. Nitric acid that is used in the process may be recovered using an evaporator. Thus, nitric acid can also be recycled, further minimizing hazardous waste. An embodiment process will allow (1) recycle of uranium and (2) efficient Mo-99 recovery after purification through an alumina column. Alumina is used routinely for purification of Mo-99, and for the delivery of Tc-99m from medical isotope generators. Thus, an embodiment process for recycling uranium that has been used for the production of Mo-99 involves providing an aqueous solution comprising uranyl nitrate and nitric acid, irradiating the solution to produce soluble fission products, the soluble fission products comprising Mo-99. Thereafter, the solution will be conditioned to recover uranium by crystallization. The crystals will comprise uranyl nitrate hydrates and a supernatant that will comprise the soluble fission products. The soluble fission products will include Mo-99, Ba-140, Zr-95, Ru-103 and Ce-141. Afterward, the process continues by preparing a second aqueous solution from the crystals, the second aqueous solution comprising uranyl nitrate and nitric acid. This second solution would be irradiated to produce soluble fission products comprising Mo-99, Ba-140, Zr-95, Ru-103 and Ce-141. Thereafter, this second solution will be conditioned to again recover uranium by crystallization. The process can be repeated again and again but unwanted activation and fission products could build up in the crystallized uranium nitrate hydrates. To prevent, or at least minimize, the buildup of unwanted activation and fission products, the recycled uranium may be periodically purified. Purification can be accomplished by a number methods including washing the crystals with nitric acid, heating the crystals to sweat out impurities prior to washing and/or undertaking a second recrystallization process. In the latter case the uranyl nitrate hydrates solid would be dissolved in nitric acid, and the resulting solution would be conditioned to yield a 350-650 gU/L solution in a nitric acid concentration of between 4-8 M prior to crystallization through concentration by evaporation under reduced pressure and/or by cooling. After purification, the crystalline uranyl nitrate hydrates could be dissolved in water, and then nitric acid would be removed by heating and/or by evaporating under reduced pressure. Water, and nitric acid if needed, can then be added to generate a 80-310 gU/L solution with a nitric acid concentration of between 0.01-0.5 mol/L that can be irradiated, thus recycling the uranium. After the solution irradiation, and uranium nitrate hydrates crystallization, the Mo-99 remains soluble in the supernatant. Mo-99 can be recovered from the supernatant using a column based process employing alumina as a sorbent after the supernatant has been conditioned to yield a concentration of nitric acid of from about 0.01 to about 0.2 M and a uranium concentration of from about 10 gU/L to about 70 gU/L. Uranium at lower concentrations (e.g., below 70 gU/L) results in comparatively low nitrate concentrations. Nitrate will bind to alumina, but at lower nitrate concentrations nitrate will not effectively compete with molybdenum in the +VI oxidation state. Molybdenum in the +VI oxidation binds strongly to the alumina in mildly acidic aqueous solution, and can be stripped from alumina in basic solution. Additional purification steps will then result in a pure Mo-99 product for use in Tc-99m generators. 80% or greater of the Mo-99 produced from the U-235 fission in dilute nitric acid may be recovered after a column-based alumina separation, with the percentage yield not corrected for radioactive decay. 93% or greater of the uranium may be recycled for future production of Mo-99. In an embodiment, a uranium nitrate solution may be concentrated through evaporation and acidified to a concentration of nitric acid of between 4 M and 8 M and uranium in an amount of, for example, 500 gU/L. Cooling to a temperature effective for crystallization, forming crystals of uranyl nitrate hydrates, an effective temperature being a temperature of from about 10° C. to about −30° C. (e.g. −10° C.) allows crystallization of 93% or greater of the uranium as uranyl nitrate hydrates, which is a largely insoluble salt at such cold temperatures. Evaporation under reduced pressure may be used as a means of both cooling the solution and lowering solution volume to increase the percentage of uranyl nitrate hydrates crystallized from solution. The crystals of uranyl nitrate hydrates are filtered from the supernatant that remains. The supernatant may be further conditioned to lower the nitric acid concentration through evaporation under reduced pressure and/or heating. An inorganic oxidant may be added either to the pre-crystallization solution and/or the post-crystallization supernatant to ensure all of the Mo-99 is in the +VI oxidation state. This is the preferred oxidation state for separation of Mo-99 from the uranium nitrate hydrates in the crystallization step and for using alumina as an absorbent. Suitable inorganic oxidants include potassium permanganate, hydrogen peroxide, and sodium persulfate. Another embodiment relates to a process for recycling uranium wherein irradiation of solid targets leads to the production of Mo-99 from U-235. Solid uranium targets can be based on several chemical compositions, including uranium metal foils, U3Si2 plates, UAlx targets and UO2 targets. Through dissolution and subsequent chemical processing of the irradiated solid targets a uranium solution of nitric acid concentration of between 4 M and 8 M, and a uranium concentration of between 350 gU/L and 650 gU/L, can be prepared. Crystallization of this solution recovers 93% or greater of the uranium as uranyl nitrate hydrates for subsequent recycle. FIG. 1 provides a flow diagram for an embodiment process. The boxes refer to a particular material and the numbers 1 through 5, which are in between boxes, refer to process steps. Thus, the top left box refers to an irradiated solution of enriched uranium having uranium concentration of from about 80 gU/L to about 310 gU/L in a dilute nitric acid solution having a concentration of from about 0.01 M to about 0.5 M. The number 1a refers to the process steps performed on the composition, which are steps that result in increasing the concentration of uranium nitrate to a concentration of from about 350 gU/L to about 650 gU/L and increasing the concentration of nitric acid to a concentration of from about 4 M to about 8 M. These results may be achieved by evaporation using heat and/or evaporation under a reduced pressure, and addition of nitric acid. This solution may be held at above ambient temperature (e.g., 40° C.) to be sure all of the uranium remains in solution. Alternatively, the top right box refers to an irradiated solid uranium target. The number 1b refers to the process steps performed on the composition, which are steps that result in dissolution and chemical processing to generate a solution with concentration of from about 350 gU/L to about 650 gU/L, and increasing the concentration of nitric acid to a concentration of from about 4 M to about 8 M. This solution may be held at above ambient temperature (e.g., 40° C.) to be sure all of the uranium remains in solution. Process step 2, which is performed on the 350 gU/L to about 650 gU/L solution, results in the formation of crystals of uranyl nitrate hydrates and a supernatant. The uranyl nitrate hydrates contain greater than 93% of the uranium. At this point the uranyl nitrate hydrates could be conditioned and converted back into a solid target for irradiation and production of Mo-99. The supernatant contains greater than 85% of the Mo-99 (not corrected for radioactive decay) and less than 7% of uranium. Process step 3, which is performed on the uranyl nitrate hydrate crystals (UO2(NO3)2.xH2O), involves dissolving the crystals in water, and subsequent evaporation using heat and/or reduced pressure to remove nitric acid. Then water will be added, and nitric acid if needed, to arrive at a dilute nitric acid solution (from about 0.01 to about 0.5 M) with a uranium concentration (350 gU/L to about 650 gU/L) suitable for recycling the uranium so that it can be used for another round of irradiation, solution conditioning, etc. Process step 4 is performed on the supernatant which contains greater than 85% of the Mo-99 (not corrected for radioactive decay) and less than 7% of the uranium. Process step 4 involves evaporation using heat and/or reduced pressure to remove nitric acid. Then water will be added, and nitric acid if required, to obtain a concentration of uranium of from about 10 gU/L to about 70 gU/L and a solution nitric acid concentration from about 0.01 M to about 0.2 M. Process step 5 is performed next, which involves using a column of alumina adsorbent to recover more than 80% of the total Mo-99 (not corrected for radioactive decay), and the uranium from this step (<7%) can be disposed of or subjected to recycle through concentration of uranium to a concentration of from about 350 gU/L to about 650 gU/L and increasing the concentration of nitric acid to a concentration of from about 4 M to about 8 M, and subsequently undertaking steps 2 and 3. The aforementioned embodiments relate to the irradiation of solutions and solid targets of uranium and subsequent recovery of molybdenum-99 for generating Tc-99m, and thus relates to satisfying an objective of using LEU for generating molybdenum-99 and subsequent recycling of the LEU. Although the present invention has been described with reference to specific details, it is not intended that such details should be regarded as limitations upon the scope of the invention, except as and to the extent that they are included in the accompanying claims.
	abstract	Devices and corresponding methods of use are described herein which may comprise an enclosing structure defining a closed loop flow path and a system generating a plasma at a plasma site, e.g. laser produced plasma system, where the plasma site may be in fluid communication with the flow path. For the device, a gas may be disposed in the enclosing structure which may include an ion-stopping buffer gas and/or an etchant. A pump may be provided to force the gas through the closed loop flow path. One or more heat exchangers removing heat from gas flowing in the flow path may be provided. In some arrangements, a filter may be used to remove at least a portion of a target species from gas flowing in the flow path.
	claims	1. A filter comprising:more than two plural filter plates that form a layer crossing X-rays, wherein each of said plural filter plates has a constant thickness and the thickness of each filter plate is successively doubled with the thinnest filter plate defined as a reference; andan adjusting device that adjusts a combination of filter plates forming the layer by individually moving the plural filter plates so as to come in and out of an X-ray passing space. 2. A filter according to claim 1, wherein the adjusting device has a pair of moving in/out mechanisms for moving the plural filter plates in and out from both sides of the X-ray passing space, wherein a first of said mechanisms moves a first set of said plural filter plates comprising every other of said plural filter plates, and a second of said mechanisms moves the remaining of said plural filter plates. 3. A filter according to claim 2, wherein the moving in/out mechanisms move the filter plates in and out by a reciprocating movement of a link based upon a rotation of a plate cam. 4. A filter according to claim 3, wherein plural plate cams present at the same side with respect to the X-ray passing space have a common rotation axis. 5. A filter according to claim 2, wherein the moving in/out mechanisms move the filter plates in and out by a swing movement of an arm driven by a motor. 6. A filter according to claim 2, wherein the moving in/out mechanisms move the filter plates in and out by using a reciprocating movement of a movable section of an electromagnetic solenoid. 7. A filter according to claim 2, wherein the moving in/out mechanisms move the filter plates in and out by using a reciprocating movement of a movable section of an air cylinder. 8. A filter according to claim 2, wherein the moving in/out mechanisms move the filter plates in and out by using a reciprocating movement of a movable section of a hydraulic cylinder. 9. An X-ray imaging apparatus for imaging a subject by X-rays via a filter, wherein the filter comprises:more than two plural filter plates that form a layer crossing X-rays, wherein each of said plural filter plates has a constant thickness and the thickness of each filter plate is successively doubled with the thinnest filter plate defined as a reference; andan adjusting device that adjusts a combination of filter plates forming the layer by individually moving the plural filter plates so as to come in and out of an X-ray passing space. 10. An X-ray imaging apparatus according to claim 9, wherein the adjusting device has a pair of moving in/out mechanisms for moving the plural filter plates in and out from both sides of the X-ray passing space, wherein a first of said mechanisms moves a first set of said plural filter plates comprising every other of said plural filter plates, and a second of said mechanisms moves the remaining of said plural filter plates. 11. An X-ray imaging apparatus according to claim 10, wherein the moving in/out mechanisms move the filter plates in and out by a reciprocating movement of a link based upon a rotation of a plate cam. 12. An X-ray imaging apparatus according to claim 11, wherein plural plate cams present at the same side with respect to the X-ray passing space have a common rotation axis. 13. An X-ray imaging apparatus according to claim 10, wherein the moving in/out mechanisms move the filter plates in and out by a swing movement of an arm driven by a motor. 14. An X-ray imaging apparatus according to claim 10, wherein the moving in/out mechanisms move the filter plates in and out by using a reciprocating movement of a movable section of an electromagnetic solenoid. 15. An X-ray imaging apparatus according to claim 10, wherein the moving in/out mechanisms move the filter plates in and out by using a reciprocating movement of a movable section of an air cylinder. 16. An X-ray imaging apparatus according to claim 10, wherein the moving in/out mechanisms move the filter plates in and out by using a reciprocating movement of a movable section of a hydraulic cylinder. 17. A filter comprising:plural filter plates that form a layer crossing X-rays, wherein each of said plural filter plates has a constant thickness; andan adjusting device that adjusts a combination of filter plates forming the layer by individually moving the plural filter plates so as to come in and out of an X-ray passing space, the adjusting device having a pair of moving in/out mechanisms for moving the plural filter plates in and out from both sides of the X-ray passing space, wherein a first of said mechanisms moves a first set of said plural filter plates comprising every other of said plural filter plates, and a second of said mechanisms moves the remaining of said plural filter plates.
053176090	summary	BACKGROUND OF THE INVENTION The present invention relates to installing fuel rods in a nuclear fuel assembly skeleton, and it is particularly applicable to fuel assemblies in which the skeleton includes guide tubes interconnecting removable end fittings and carrying grids that delimit cells distributed at the nodes of a regular array and designed to receive the rods. Such assemblies are used in nuclear reactors that are cooled and moderated by water, in particular by pressurized water. An apparatus is already known for installing fuel rods in such a skeleton, of the type which comprises receiving means for receiving a skeleton without end nozzles, interposed between a magazine for storing fuel rods in alignment with locations in the skeleton for receiving the rods, and a displacement mechanism for displacing pull bars longitudinally towards the magazine and away from the magazine, the pull rods being terminated by clamps for grasping the rods to be inserted in the skeleton. This applies in particular when the cells in the grids are distributed in a square array, with the displacement mechanism often being provided with the same number of pull bars as there are cells in a layer and enabling an entire layer of rods to be installed simultaneously in the skeleton. After the rods in one layer have been inserted, the mechanism is displaced transversely relative to the layer through a distance equal to the pitch between layers and is used to load a new layer of rods. The shape of the clamps on the pull bars is such that, while they are being displaced towards the magazine through the grids, they run the risk of damaging the springs and/or the projections provided on the plates that constitute the grids for the purpose of holding the rods in place. To avoid this risk, it is common practice to place caps having an externally tapered shape on the clamps before inserting the pull bars into the skeleton. The caps are removed when the clamps are in an intermediate position between the outlets from the skeleton and the magazine. At present, these operations are performed manually. They are lengthy, particularly the operation of installing the caps. They require an operator to remain in the vicinity of the fuel rods. Unfortunately, greater and greater use is being made of rods that contain reprocessed fuel and/or plutonium, thereby running the risk of irradiating the operators. SUMMARY OF THE INVENTION It is an object of the present invention to provide rod- ling apparatus that satisfies practical requirements better than prior art apparatuses, and in particular that eliminate any need for manual placement of the caps on the clamps. To this end, the invention provides apparatus of the kind defined above, further comprising a cap-placing assembly interposed between the skeleton-receiving means and the displacement mechanism, the assembly having a support fixed to these means and a removable plate that is formed with cap-retaining housings disposed in an array that reproduces the array of rod locations, the shape of the caps being such that the clamps, when closed, engage inside the caps when the pull bars are moved forwardly toward the magazine. This disposition makes it possible to load the caps into the removable plate in a zone that is protected against radiation. The manual operation that remains necessary consists merely in fixing the plate or the receptacle that includes the plate on the fixed support prior to installing the rods of an assembly, and then in removing it once empty in order to replace it with another that is full, after the rods have been installed. In an advantageous embodiment, making it possible to further reduce the exposure time of an operator, the apparatus further includes a cap-removing assembly comprising a frame interposed between the skeleton-receiving means and the magazine, having a frame carrying retaining jaws that are displaceable transversely to the displacement direction of the pull bars between a position in which they hold at least some of the caps and a position in which they release the caps. Such unit makes it possible to retain the terminal caps of a set of pull bars (e.g corresponding to a layer of rods) and to remove the caps, by slightly pulling the pull bars back and then releasing the caps. This can be done merely by displacing the frame transversely to the direction of the pull bars in order to leave room for the pull bars to pass, and to enable the clamps that terminate them to advance and grasp rods placed in the magazine. The invention also provides a method suitable for being implemented with the above-defined apparatus, comprising the steps of placing a skeleton without end nozzles horizontally between a storage magazine that stores rods in alignment with rod-receiving emplacements in the skeleton and a mechanism for longitudinally displacing pull bars terminated by rod-grasping clamps towards the magazine and away from the magazine; passing the pull bars through the skeleton up to the magazine and grasping respective rods; and pulling the rods into the skeleton. The method is characterized in that caps are loaded, at a distance from the magazine, into housings of a receptacle, the housings being distributed in the same array as the rods; the receptacle is interposed between the displacement mechanism and the skeleton; the pull bars are advanced for the clamps to be engaged inside the caps as they pass through the receptacle prior to passing through the skeleton; and on leaving the skeleton the caps are removed without manual intervention prior to bringing the clamps up to the magazine. The invention will be better understood on reading the following description of a particular embodiment given by way of example.
	description	The present invention relates to a pH adjusting system and a pH adjusting method for adjusting pH in a reactor container at abnormal time of a nuclear reactor stored in the reactor container. As a nuclear power plant in the past, a nuclear power plant including a pressurized water reactor is known. In this nuclear power plant, a primary cooling system such as the pressurized water reactor or a steam generator is stored in a reactor container (see, for example, Non-Patent Document 1). A spray facility for spraying spray water into the reactor container is provided around the nuclear container on the assumption of an abnormal situation. As shown in FIG. 10, this spray facility includes a water tank for refueling disposed on the outside of the reactor container and serving as a water source, a spray ring disposed in the reactor container, a first spray pipe that connects the water tank for refueling and the spray ring, and a spray pump interposed in the first spray pipe. A storage container recirculation sump that is provided at the bottom of the reactor container and stores the sprayed spray water is provided in this spray facility. The storage container recirculation sump is connected to the first spray pipe between water tank for refueling and the spray pump via a second spray pump. If an abnormal situation occurs, the pressure in the reactor container is increased by an evaporated primary coolant (light water). In such a case, the spray facility operates, more specifically, the spray pump is driven to spray the spray water from the water tank for refueling into the reactor container via the spray ring, whereby the inside of the reactor container is cooled to reduce the pressure in the reactor container. Thereafter, the sprayed spray water is stored in the storage container recirculation sump and the stored spray water is sprayed from the spray ring again through the second spray pipe. In other words, the spray facility is configured such that the spray water circulates in the reactor container. In the spray facility, to remove radioactive iodine contained in the evaporated light water, an iodine removal chemical tank that stores an iodine removal chemical, a spray eductor interposed in the first spray pipe, a chemical injection flow path that connects the iodine removal chemical tank and the spray eductor, and an on-off valve interposed in the chemical injection flow path are provided. Consequently, at abnormal time, the on-off valve is opened and the iodine removal chemical is injected into the first spray pipe via the spray eductor to mix the iodine removal chemical and the spray water. The mixture of the iodine removal chemical and the spray water is sprayed into the reactor container to remove the radioactive iodine in the reactor container. In this case, in general, strong alkali caustic soda is used as the iodine removal chemical. Therefore, to reduce burdens of management and operation of the chemical and a test of a chemical injection line valve, a pH adjusting system described below is also adopted. For example, it is known that a mesh basket containing a pH adjuster such as trisodium phosphate is arranged on a base level near an outer peripheral wall in the nuclear reactor (on a floor of the storage container recirculation sump) (see, for example Non-Patent Document 2). With this configuration, when the spray water is sprayed by the spray facility at abnormal time, the storage container recirculation sump is filled with the spray water. Then, the basket disposed on the floor of the storage container recirculation sump is submerged and the pH adjuster stored in the basket dissolves in the spray water. Thereafter, the spray water in which the pH adjuster dissolves is circulated in the reactor container by the spray facility. This makes it possible to adjust pH in the reactor container. The radioactive iodine can be kept in the solution by adjusting pH in the reactor container. The deterioration in durability of structural materials and various devices in the reactor container can be controlled by adjusting pH in the reactor container. Boric acid is dissolved in the light water to decelerate neutrons generated by the nuclear fission reaction. Therefore, the light water is low in pH and acidic. The recirculated water is likely to deteriorate durability of materials of devices and pipes that recirculate the light water for a long period after an accident. However, the deterioration in durability of the devices and the pipes can be controlled by adjusting pH in the reactor container to be neutral. Non-Patent Document 1: “Genkai Nuclear Power Plant, Application for Permission of a Change in the Nuclear Reactor (A Change in Nos. 3 and 4 Nuclear Reactor Facilities)”, Kyushu Electric Power Co., Inc., April 1990, Attached Document 8, p. 8-5-8 to 8-5-10 and p. 8-5-18 Non-Patent Document 2: J. A. Reinhart Site Director/Fort Calhoun Station, “Fort Calhoun Station, Unit No. 1 License Amendment Request (LAR) ‘Change of Containment Building Sump Buffering Agent from Trisodium Phosphate to Sodium Tetraborate’”, [online], Aug. 21, 2006, U.S.NRC, [retrieved on Oct. 17, 2007], Internet <URL: http://www.nrc.gov/→select Electrpnic Reading Room→select Documents in ADAMS→select Web-based access→select Begin ADAMS Search→Input “ML062340039”→select Rank 5. (80)> However, in the nuclear power plant, in design, it may be difficult to set the basket on the floor of the storage container recirculation sump. Such difficulty occurs, for example, when boric water is always filled in a water storage tank set at the bottom of the storage container or when a space for arranging the basket on the floor of the storage container recirculation sump cannot be secured. Therefore, it is an object of the present invention to provide a pH adjusting system and a pH adjusting method that can suitably perform pH adjustment in a reactor container even if it is difficult to dispose a pH adjusting apparatus on a floor of an internal water storage tank. According to an aspect of the present invention, a pH adjusting system comprises an internal water storage tank that is disposed in a reactor container, which stores a nuclear reactor, and is capable of storing cooling water; and a pH adjusting apparatus that is disposed above the internal water storage tank and stores a pH adjuster. The pH adjusting apparatus causes a pH-adjusted solution generated by dissolving or mixing the pH adjuster to flow out to the internal water storage tank below the pH adjusting apparatus. In the pH adjusting system, the pH adjuster may be prepared in a powder state. The pH adjusting system may further comprise a solvent injecting unit that is capable of injecting a solvent for dissolving or diluting the pH adjuster into the pH adjusting apparatus. The pH adjusting apparatus may dissolve or mix the pH adjuster in the solvent, which is injected by the solvent injecting unit, to generate a pH-adjusted solution and may cause the generated pH-adjusted solution to flow out to the internal water storage tank below the pH adjusting apparatus. The pH adjusting system may further comprise a spraying unit that is capable of spraying the cooling water stored in the internal water storage tank into an inside of the reactor container. The spraying unit may also function as the solvent injecting unit and the cooling water may be used as the solvent, and the pH adjusting apparatus may be disposed below the spraying unit. The pH adjusting system may further comprise an external water storage tank that is provided on an outside of the reactor container and is capable of storing the solvent. The solvent injecting unit may inject the solvent, which is stored in the external water storage tank, into the pH adjusting apparatus. In the pH adjusting system, the solvent injecting unit may inject the cooling water, which is stored in the internal water storage tank, into the pH adjusting apparatus as the solvent. In the pH adjusting system, the pH adjusting apparatus may include a pH adjuster, a basket containing the pH adjuster, and a basket housing container housing the basket. An inlet through which the solvent injected from the solvent injecting unit flows in, and an outlet from which the pH-adjusted solution generated by dissolving or mixing the pH adjuster in the solvent flows out to the internal water storage tank are formed in the basket housing container. In the pH adjusting system, the outlet of the basket housing container may include an overflow pipe, and a start edge of the overflow pipe is located at a bottom of the basket housing container. In the pH adjusting system, a terminal end of the overflow pipe may be connected to the internal water storage tank. In the pH adjusting system, the pH adjusting apparatus may further include a vent pipe provided in the overflow pipe to vent the overflow pipe. According to another aspect of the present invention, a pH adjusting system comprises a reactor container that stores a nuclear reactor; an internal water storage tank that is disposed in a reactor container and is capable of storing cooling water; a spraying unit that is capable of spraying the cooling water, which is stored in the internal water storage tank, to an inside of the reactor container at abnormal time; and a pH adjusting apparatus that is disposed above the internal water storage tank and below the spraying unit and stores a pH adjuster therein. The pH adjusting apparatus includes the pH adjuster, a basket containing the pH adjuster, and a basket housing container that houses the basket therein, and is formed therein an inlet through which the cooling water sprayed from the spraying unit flows in and an outlet from which the pH-adjusted solution generated by dissolving the pH adjuster in the cooling water flows out to the internal water storage tank. According to still another aspect of the present invention, a pH adjusting system comprises a reactor container that stores a nuclear reactor; an internal water storage tank that is disposed in a reactor container and is capable of storing cooling water; a pH adjusting apparatus that is disposed above the internal water storage tank and stores a pH adjuster therein; and a solvent injecting unit that is capable of injecting the cooling water, which is stored in the internal water storage tank, into the pH adjusting apparatus as a solvent for dissolving or diluting the pH adjuster at abnormal time. The pH adjusting apparatus includes the pH adjuster, a basket containing the pH adjuster, and a basket housing container that houses the basket therein. The basket housing container includes an inlet through which the cooling water injected from the solvent injecting unit flows in and an outlet from which the pH-adjusted solution generated by dissolving the pH adjuster in the cooling water flows out to the internal water storage tank. According to still another aspect of the present invention, a pH adjusting method for adjusting pH in a reactor container at abnormal time of a reactor stored in the reactor container comprises a pH-adjusted-solution generating for injecting a solvent for dissolving or diluting a pH adjuster into a pH adjusting apparatus that stores the pH adjuster therein and dissolving or mixing the pH adjuster in the solvent to generate a pH-adjusted solution; and a mixing for causing the pH-adjusted solution, which is generated at the pH-adjusted-solution generating, to flow into an internal water storage tank that is provided below the pH adjusting apparatus and stores cooling water and mixing the pH-adjusted solution in the cooling water. The pH adjusting method may further comprises a spraying for spraying the cooling water mixed with the pH-adjusted solution in the mixing into an inside of the reactor container. With the pH adjusting system according to the present invention, the pH adjusting apparatus can surely cause the pH-adjusted solution generated by dissolving or mixing the pH adjuster to flow into the internal water storage tank below the pH adjusting apparatus. Therefore, it is possible to dispose the pH adjusting apparatus above the internal water storage tank, mix the pH-adjusted solution in the cooling water, and suitably perform pH adjustment in the reactor container. In other words, even if there is no space for disposing the pH adjusting apparatus on the floor of the internal water storage tank, it is possible to dispose the pH adjusting apparatus in an arbitrary position above the internal water storage tank. It is preferable to dispose the pH adjusting apparatus in a free space in the reactor container. This makes it possible to effectively make use of the free space and dispose the pH adjusting apparatus without changing an existing configuration. When the pH adjuster is in a solid state, the pH adjuster is dissolved into the pH-adjusted solution. When the pH adjuster is in a liquid state, the pH adjuster is diluted into the pH-adjusted solution. With the pH adjusting system according to the present invention, because the pH adjuster can be prepared in a powder state, the pH adjuster can be prepared to be easily dissolved. This makes it possible to efficiently generate a pH-adjusted solution with the pH adjusting apparatus. With the pH adjusting system according to the present invention, it is possible to inject the solvent into the pH adjusting apparatus by the solvent injecting means. Therefore, it is possible to dissolve or mix the pH adjuster in the solvent to generate a pH-adjusted solution. With the pH adjusting system according to the present invention, because the cooling water stored in the internal water storage tank is sprayed into the reactor container by the spraying means, it is possible to efficiently cool the inside of the reactor container. Because the sprayed cooling water flows into the internal water storage tank again, it is possible to circulate the cooling water in the reactor container. Moreover, because the spraying means also serves as the solvent injecting means, it is possible to reduce the number of components of the pH adjusting system and simplify a configuration of the pH adjusting system. With the pH adjusting system according to the present invention, it is possible to provide the external water storage tank and inject the solvent stored in the external water storage tank into the pH adjusting apparatus. Therefore, because it is unnecessary to dispose the pH adjusting apparatus right below the spraying means unlike the pH adjusting apparatus according to the previously mentioned invention, it is possible to improve a degree of freedom of a disposition position of the pH adjusting apparatus. With the pH adjusting system according to the present invention, it is possible to inject the cooling water stored in the internal water storage tank into the pH adjusting apparatus as the solvent. Therefore, because it is unnecessary to dispose the pH adjusting apparatus right below the spraying means unlike the pH adjusting apparatus according to the previously mentioned invention, it is possible to improve a degree of freedom of a disposition position of the pH adjusting apparatus. With the pH adjusting system according to the present invention, because the solvent (the cooling water) is caused to flow into the basket housing container by the solvent injecting means (the spraying mean) through the inlet in a state in which the basket containing the pH adjuster is stored in the basket housing container, it is possible to submerge the basket in the solvent. In other words, it is possible to dissolve or mix the pH adjuster in the solvent by submerging the pH adjuster in the solvent. This makes it possible to generate a pH-adjusted solution. The generated pH-adjusted solution can flow into the internal water storage tank through the outlet. Because the generated pH-adjusted solution flows into the internal water storage tank in a free fall, it is unnecessary to use a driving system such as an on-off valve or a pump. In other words, it is possible to supply the pH-adjusted solution to the internal water storage tank simply by injecting the solvent into the basket housing container. Consequently, because a supply failure of the pH-adjusted solution due to an operation failure of the driving system is not caused, it is possible to improve not only reliability of the pH adjusting apparatus and but also reliability of the pH adjusting system. Because the solvent in the basket housing container flows from the inlet to the outlet, compared with a method of simply submerging the basket as in the past, it is possible to efficiently dissolve the pH adjuster. It is preferable to configure the basket using a mesh or the like. With the pH adjusting system according to the present invention, the outlet includes the overflow pipe and the start end point of the overflow pipe is located at the bottom of the basket housing container. Therefore, it is possible to cause the high-density pH-adjusted solution, which tends to stay at the bottom, to flow out to the internal water storage tank. In other words, the pH-adjusted solution moves further downward as the density is higher. Therefore, by adopting the configuration described above, it is possible to satisfactorily cause the pH-adjusted solution to flow out without causing the high-density pH-adjusted solution to stay at the bottom of the basket housing container. With the pH adjusting system according to the present invention, because the terminal end of the overflow pipe is connected to the internal water storage tank, it is possible to appropriately lead the pH-adjusted solution to the internal water storage tank. With the pH adjusting system according to the present invention, the pH adjusting system includes the vent pipe for opening the inside of the duct of the overflow pipe to the atmosphere. Therefore, a siphon effect due to filling of the overflow pipe with the solvent (the cooling water) is not caused. With the pH adjusting system according to the present invention, because the cooling water is sprayed over the pH adjusting apparatus by the spraying means at abnormal time, it is possible to cause the cooling water to flow into the basket housing container through the inlet. When the cooling water flows into the basket housing container, the basket housing container is filled with the cooling water and the basket is submerged. When the basket is submerged, because the pH adjuster is dissolved in the cooling water, the pH-adjusted solution is generated. The generated pH-adjusted solution flows into the internal water storage tank through the outlet. By configuring the pH adjusting apparatus as described above, it is possible to dispose the pH adjusting apparatus above the internal water storage tank. In other words, even if there is no space for disposing the pH adjusting apparatus on the floor of the internal water storage tank, it is possible to dispose the pH adjusting apparatus in an arbitrary position above the internal water storage tank. Because the generated pH-adjusted solution is caused to flow into the internal water storage tank in a free fall, it is unnecessary to use a driving system such as an on-off valve or a pump. In other words, it is possible to supply the pH-adjusted solution to the internal water storage tank simply by injecting the solvent into the basket housing container. Consequently, because a supply failure of the pH-adjusted solution due to an operation failure of the driving system is not caused, it is possible to improve not only reliability of the pH adjusting apparatus but also reliability of the pH adjusting system. With the pH adjusting system according to the present invention, the cooling water is injected into the pH adjusting apparatus by the solvent injecting means at abnormal time. Therefore, it is possible to cause the cooling water to flow into the basket housing container through the inlet. When the cooling water flows into the basket housing container, the basket housing container is filled with the cooling water and the basket is submerged. When the basket is submerged, because the pH adjuster is dissolved in the cooling water, the pH-adjusted solution is generated. The generated pH-adjusted solution flows into the internal water storage tank through the outlet. It is possible to dispose the pH adjusting apparatus above the internal water storage tank by configuring the pH adjusting apparatus as described above. In other words, even if there is no space for disposing the pH adjusting apparatus on the floor of the internal water storage tank, it is possible to dispose the pH adjusting apparatus in an arbitrary position above the internal water storage tank. With the pH adjusting method according to the present invention, it is possible to dispose the pH adjusting apparatus above the internal water storage tank provided in the reactor container and suitably perform adjustment of pH in the reactor container. With the pH adjusting method according to the present invention, it is possible to spray the cooling water mixed with the pH-adjusted solution into the reactor container. This makes it possible to satisfactorily perform pH adjustment in the reactor container. 1 nuclear power plant 5 nuclear reactor 10 reactor container 30 pH adjusting system 35 water pit for refueling 36 spray facility 37 pH adjusting apparatus 42 inspection rack 45 spray ring 46 spray pump 50 basket 51 basket housing container 52 overflow pipe 53 vent pipe 201 pH adjusting system (second embodiment) 205 water tank for refueling 301 pH adjusting system (third embodiment) 305 water filling facility 307 injection nozzle 308 water filling pipe 309 ECCS pump 401 water filling pump A nuclear power plant to which a pH adjusting system according to the present invention is applied is explained below referring to the attached drawings. The present invention is not limited by embodiments described below. In a nuclear power plant according to this embodiment, a pressurized water reactor (PWR) is used as a nuclear reactor. In a pressurized water nuclear power plant, after light water as a primary coolant is heated in the nuclear reactor, the high-temperature light water is sent to a steam generator by a pump. In the nuclear power plant, the high-temperature light water is subjected to heat exchange with a secondary coolant to evaporate the secondary coolant. The evaporated secondary coolant (steam) is sent to a turbine to drive a generator, whereby power generation is performed. FIG. 1 is a schematic diagram of the nuclear power plant according to this embodiment. FIG. 2 is a schematic diagram of a pH adjusting system according to this embodiment. FIG. 3 is a side sectional view of a reactor container. FIG. 4 is a plan sectional view of the reactor container. A configuration of the nuclear power plant is explained referring to FIG. 1. As shown in FIG. 1, the nuclear power plant 1 has a nuclear reactor 5 and a steam generator 7 connected to the nuclear reactor 5 via a pair of coolant pipes 6a and 6b made of a cold leg 6a and a hot leg 6b. A pressurizer 8 is interposed in the hot leg 6b of the pair of coolant pipes 6a and 6b. A coolant pump 9 is interposed in the cold leg 6a. A primary cooling system 3 of the nuclear power plant 1 includes the nuclear reactor 5, the pair of coolant pipes 6a and 6b, the steam generator 7, the pressurizer 8, and the coolant pump 9, which are housed in a reactor container 10. In the configuration described above, the light water as the primary coolant flows into the steam generator 7 from the nuclear reactor 5 through the hot leg 6b. Thereafter, the light water flowing out through the steam generator 7 flows into the nuclear reactor 5 through the cold leg 6a. In other words, the light water is circulating between the nuclear reactor 5 and the steam generator 7. Boric acid is dissolved in the light water to decelerate neutrons generated by the nuclear fission reaction of the nuclear reactor 5. The light water is acidic. In other words, the light water is used as a coolant and a neutron decelerator. The nuclear reactor 5 is the pressurized water reactor as described above. The inside of the nuclear reactor 5 is filled with the light water. In the nuclear reactor 5, a large number of fuel assemblies 15 are housed and a large number of control rods 16 that controls atomic fission of the fuel assemblies 15 are provided to be insertable in the fuel assemblies 15. When the fuel assemblies 15 are subjected to atomic fission while the atomic fission reaction is controlled by the control rods 16, thermal energy is generated by this atomic fission. The generated thermal energy heats the light water and the heated light water is sent to the steam generator 7 via the hot leg 6b. On the other hand, the light water sent from the steam generator 7 via the cold leg 6a flows into the nuclear reactor 5 and cools the inside of the nuclear reactor 5. The pressurizer 8 interposed in the hot leg 6 pressurizes the high-temperature light water to thereby control boiling of the light water. The steam generator 7 subjects the high-temperature light water to heat exchange with the secondary coolant to thereby evaporate the secondary coolant to generate steam and cool the high-temperature and high-pressure light water. The coolant pump 9 circulates the light water in the primary cooling system 3, sends the light water into the nuclear reactor 5 from the steam generator 7 via the cold leg 6a, and sends the light water into the steam generator 7 from the nuclear reactor 5 via the hot leg 6b. A series of operations in the primary cooling system 3 of the nuclear power plant 1 are explained. When the light water is heated by the thermal energy generated by the atomic fission reaction in the nuclear reactor 5, the heated light water is sent to the steam generator 7 by the coolant pump 9 via the hot leg 6b. The high-temperature light water passing through the hot leg 6b is pressurized by the pressurizer 8 and boiling thereof is controlled. The light water flows into the steam generator 7 in a high-temperature and high-pressure state. The high-temperature and high-pressure light water flowing into the steam generator 7 is cooled by being subjected to heat exchange with the secondary coolant. The cooled light water is sent to the nuclear reactor 5 by the coolant pump 9 via the cold leg 6a. When the cooled light water flows into the nuclear reactor 5, the nuclear reactor 5 is cooled. The nuclear power plant 1 has a turbine 22 connected to the steam generator 7 via a steam pipe 21, a steam condenser 23 connected to the turbine 22, and a feed water pump 24 interposed in a condensing and feeding pipe 26 that connects the steam condenser 23 and the steam generator 7. A secondary cooling system 20 includes these units. A secondary coolant circulating through the secondary cooling system 20 evaporates in the steam generator 7 to be gas (steam) and is changed from the gas to liquid in the steam condenser 23. A generator 25 is connected to the turbine 22. When the steam flows into the turbine 22 from the steam generator 7 via the steam pipe 21, the turbine 22 rotates. When the turbine 22 rotates, the generator 25 connected to the turbine 22 performs heat generation. Thereafter, the steam flowing out from the turbine 22 flows into the steam condenser 23. Cooling pipes 27 are disposed in the steam condenser 23. An intake pipe 28 for supplying cooling water (e.g., seawater) is connected to one of the cooling pipes 27. A drainage pipe 29 for draining the cooling water is connected to the other of the cooling pipes 27. The steam condenser 23 cools the steam, which flows in from the turbine 22, with the cooling pipe 27 to change the steam to liquid. The secondary coolant changed to the liquid is sent to the steam generator 7 by the feed water pump 24 via the condensing and feeding pipe 26. The secondary coolant sent to the steam generator 7 is subjected to heat exchange with the primary coolant to be changed to the steam again in the steam generator 7. In the nuclear power plant 1, a pH adjusting system 30 for cooling the inside of the reactor container 10 and controlling evaporation of radioactive iodine and a fall in durability of structural materials and the like is incorporated. The pH adjusting system 30 in this embodiment is explained below referring to FIGS. 2 to 5. This pH adjusting system 30 is a system for cooling the inside of the reactor container 10 and controlling evaporation of radioactive iodine and a fall in durability of structural materials and the like at abnormal time. As shown in FIGS. 2 and 3, the pH adjusting system 30 includes the reactor container 10 described above, a water pit for refueling 35 (an internal water storage tank) provided at the bottom in the reactor container 10, a spray facility 36 (solvent injecting means and spraying means) that can spray boric water (cooling water and the solvent) stored in the water pit for refueling 35 in the reactor container 10, and three pH adjusting apparatuses 37 for adjusting pH in the reactor container 10. As shown in FIG. 3, the reactor container 10 integrally includes a container sealing section 40 formed in a hollow semispherical shape and a container main body section 41 formed in a bottomed cylindrical shape. The nuclear reactor 5, the pair of coolant pipes 6a and 6b, the steam generator 7, the pressurizer 8, and the coolant pump 9 are stored in the reactor container 10. The nuclear reactor 5 is disposed in the center of the reactor container 10. For example, two steam generators 7 are disposed to be adjacent to each other on both sides of the nuclear reactor 5. An inspection rack 42 formed in a horseshoe shape in plan view is disposed in an upper part of a container main body section 41 of the reactor container 10 along an inner wall thereof (see FIG. 4). The inspection rack 42 includes a grating or the like. The three pH adjusting apparatuses 37 are disposed on this inspection rack 42. The inside of the reactor container 10 is configured such that boric acid water sprayed from a spray ring 45 described later returns to the water pit for refueling 35. The water pit for refueling 35 is disposed at the bottom of the reactor container 10 and is disposed in a horseshoe shape in plan view in a peripheral direction along an inner wall of the reactor container 10 (see FIG. 4). The inside of the water pit for refueling 35 is always filled with boric acid water. Usually, this boric acid water is used for refueling the fuel assemblies 15. However, at abnormal time of the reactor 5, this boric acid water is also used as cooling water for cooling the inside of the reactor container 10. This boric acid water is also used as a solvent of a pH adjuster described later. The water pit for refueling 35 is not limited to the configuration described above. A plurality of water pits for refueling can be disposed at equal intervals in the peripheral direction along the inner wall of the reactor container 10. As shown in FIG. 2, the spray facility 36 includes four spray rings 45 (see FIG. 3) provided in a container ceiling section 40 in the reactor container 10, a spray pipe 47 that connects the four spray rings 45 and the water pit for refueling 35, and a spray pump 46 interposed in the spray pipe 47. As shown in FIG. 3, the respective spray rings 45 are formed in ring shapes having different diameters. The four spray rings 45 are disposed in parallel to a center axis direction in a state in which the centers thereof are aligned and are disposed such that the diameters increase from a ceiling side to a bottom side. The diameter of the spray ring 45 located at the top of the container ceiling section 40 is the smallest and the diameter of a spray ring 45d located at the bottom is the largest. The spray pump 46 pumps up the boric acid water stored in the water pit for refueling 35 and supplies the boric acid water to the four spray rings 45. As shown in FIG. 4, the three pH adjusting apparatuses 37 are disposed in arbitrary positions of the inspection rack 42, respectively. The pH adjusting apparatuses 37 are attached to an inner wall of the container main body section 41 and disposed at intervals in a peripheral direction of the container main body section 41. In other words, the three pH adjusting apparatuses 37 are disposed above the water pit for refueling 35 and disposed right below the spray ring 45d at the bottom (see FIG. 3). Consequently, the respective pH adjusting apparatuses 37 are disposed in water spray positions of water spray nozzles of the spray ring 45d at the bottom. As shown in FIG. 5, each of the pH adjusting apparatuses 37 has a pH adjuster, a plurality of baskets 50 (one is shown in FIG. 5) that include the pH adjuster, a basket housing container 51 that houses the basket 50, an overflow pipe 52 provided in the basket housing container 51, and a vent pipe 53 provided in the overflow pipe 52. The number of baskets 50 housed in the basket housing container 51 is different for each of the three pH adjusting apparatuses 37. Prepared twenty-three baskets 50 in total are housed by being divided in such a manner that seven baskets, seven baskets, and nine baskets are housed in basket housing containers 51 of the respective pH adjusting apparatuses 37 (see FIG. 4). As the pH adjuster, for example, sodium tetraborate decahydrate (NaTB) is used. The pH adjuster is formed in a powder state to be easily dissolved in the boric acid water. In this embodiment, NaTB is used as the pH adjuster. However, the pH adjuster is not limited to this. Trisodium phosphate (TSP) and the like can be used. Each of the baskets 50 containing the pH adjuster is formed in a rectangular parallelepiped shape. A part of the basket 50 (e.g., upper and lower surfaces or sides) is formed by using a mesh. Consequently, because the boric acid water penetrates into the inside of the basket 50, it is possible to make it easy to dissolve the pH adjuster. The pH adjuster in the powder state does not flow out to the outside of the basket 50. The basket housing container 51 is formed in a box shape opened in an upper surface and is formed to be vent along the inner wall of the container main body section 41. A plurality of baskets 50 are housed in the basket housing container 51. When the boric acid water is sprayed from the spray ring 45d located right above over the basket housing container 51, the sprayed boric acid water is stored in the basket housing container 51 via openings of upper surfaces of the baskets 50 and submerges the baskets 50 housed therein. In other words, the openings of the upper surfaces of the baskets 50 are inlets of the boric acid water. An outlet of the basket housing container 51 includes the overflow pipe 52. The overflow pipe 52 is formed in a substantially reverse “U” shape. In other words, a start end of the overflow pipe 52 is located at the bottom in the basket housing container 51, the overflow pipe 52 extends upward from the start end along an inner wall of the basket housing container 51, bends in the horizontal direction in a sidewall upper part of the basket housing container 51, and pierces through the sidewall upper part. The overflow pipe 52, which pierces through the sidewall upper part, extends downward along an outer wall of the basket housing container 51, and a terminal end of the overflow pipe 52 is connected to the water pit for refueling 35. An aperture of the overflow pipe 52 is set to an aperture for preventing a duct of the overflow pipe 52 from being filled with the boric acid water, whereby occurrence of the siphon effect is controlled. In this case, it is preferable to dispose overflow pipes 52 in a number same as the number of baskets 50 housed in the basket housing container 51. It is preferable that terminal ends of a plurality of overflow pipes 52 are disposed at intervals in a peripheral direction of the reactor container 10 with respect to the water pit for refueling 35 provided in the peripheral direction. This makes it possible to cause the pH-adjusted solution to evenly flow into the water pit for refueling 35. Therefore, it is possible to quickly and equally perform pH adjustment. The vent pipe 53 is formed in a substantially reverse “J” shape and disposed above the overflow pipe 52. The vent pipe 53 connects the inside and the outside of the overflow pipe 52. The vent pipe 53 opens the inside of the duct of the overflow pipe 52 to the atmosphere to prevent the inside of the duct of the overflow pipe 52 from being filled with the boric acid water. Consequently, the siphon effect due to the filling of the overflow pipe 52 with the boric acid water is not caused. In other words, because the boric acid water sprayed from the spray ring 45d passes through the basket 50 and flows out from the overflow pipe 52, the pH adjuster in the basket 50 is always exposed to the flowing boric acid water. It is also possible that the vent pipe 53 is not provided, an aperture of the overflow pipe 52 is set to an aperture with which the siphon effect is caused, and a strong flow of the boric acid water due to the siphon effect is repeatedly given to the pH adjuster in the basket 50 to facilitate the dissolution of the pH adjuster. A series of operations in the pH adjusting system 30 are explained. When an abnormal situation occurs, first, the spray facility 36 operates. In other words, the spray pump 46 is driven to pump up the boric acid water from the water pit for refueling 35 and spray the pumped-up boric acid water into the reactor container 10 via the four spray rings 45. At this point, a part of the boric acid water sprayed from the spray ring 45d located at the bottom flows into the pH adjusting apparatus 37. The other parts of the boric acid water cool the inside of the reactor container 10. When the boric acid water is sprayed over the pH adjusting apparatus 37, the boric acid water flows into the basket housing container 51. Then, the basket housing container 51 is filled with the boric acid water and the basket 50 is submerged. When the basket 50 is submerged, because the pH adjuster is dissolved in the boric acid water, the pH-adjusted solution is generated (a pH-adjusted-solution generating). The generated pH-adjusted solution flows into the water pit for refueling 35 in a free fall via the overflow pipe 52. In other words, it is possible to cause the generated pH-adjusted solution to flow into the water pit for refueling 35 without using a driving system such as an on-off valve or a pump. Therefore, a supply failure of the pH-adjusted solution due to a failure of the driving system is not caused. Consequently, it is possible to improve not only reliability of the pH adjusting apparatus 37 but also reliability of the pH adjusting system 30. Because the start end of the overflow pipe 52 is located at the bottom of the basket housing container 51, it is possible to appropriately lead the high-density pH-adjusted solution, which tends to stay at the bottom, to the overflow pipe 52. Moreover, because the terminal end of the overflow pipe 52 is connected to the water pit for refueling 35, it is possible to appropriately lead the pH-adjusted solution, which flows through the overflow pipe 52, to the water pit for refueling 35. The pH-adjusted solution, which flows into the water pit for refueling 35, is mixed with the boric acid water in the water pit for refueling 35 (a mixing step). Thereafter, the boric acid water mixed with the pH-adjusted solution in the water pit for refueling 35 is pumped up the by spray pump 46 and the pumped-up boric acid water is sprayed into the reactor container 10 via the four spray rings 45 (a spraying step). Consequently, because the pH-adjusted solution circulates in the reactor container 10, pH in the reactor container 10 is adjusted and the inside of the reactor container 10 is cooled. With the configuration described above, the pH adjusting apparatus 37 can be configured to be capable of generating the pH-adjusted solution at abnormal time and cause the generated pH-adjusted solution to flow into the water pit for refueling 35 below the pH adjusting apparatus 37. Consequently, it is possible to dispose the pH adjusting apparatus 37 above the water pit for refueling 35. In other words, even if there is no space for disposing the pH adjusting apparatus 37 on the floor of the water pit for refueling 35, it is possible to dispose the pH adjusting apparatus 37 in an arbitrary position above the water pit for refueling 35. It is possible to effectively make use of a free space by disposing the pH adjusting apparatus 37 on the inspection rack 42. The boric acid water sprayed by the spray facility 36 falls on the pH adjusting apparatus 37. In other words, the spray facility 36 simultaneously performs spraying of the boric acid water into the reactor container and injection of the boric acid water into the pH adjusting apparatus. Therefore, it is unnecessary to provide a new solvent injection system that injects the boric acid water into the pH adjusting apparatus 37. Consequently, it is possible to simplify the configuration of the pH adjusting system 30 without increasing the number of components. Moreover, because the pH adjusting apparatus 37 is configured without using a driving system, a supply failure of the pH-adjusted solution due to an operation failure of the driving system does not occur. Consequently, it is possible to improve not only reliability of the pH adjusting apparatus 37 but also reliability of the pH adjusting system 30. Although not shown in the figure, for example, a water collecting member formed in a funnel shape can be interposed between the spray ring 45d located at the bottom and the pH adjusting apparatus 37. With this configuration, because the boric acid water sprayed from the spray ring 45d can be effectively collected, it is possible to increase a flow rate of the boric acid water that flows into the pH adjusting apparatus 37. Consequently, it is possible to efficiently perform generation of the pH-adjusted solution by the pH adjusting apparatus 37. The nuclear power plant 1 to which the pH adjusting system 201 according to a second embodiment is applied is explained referring to FIGS. 6 and 7. To avoid a redundant description, only sections different from those described above are explained. FIG. 6 is a schematic diagram of a pH adjusting system at normal time according to the second embodiment. FIG. 7 is a schematic diagram of the pH adjusting system at abnormal time according to the second embodiment. In the first embodiment, the water pit for refueling 35 is provided at the bottom of the reactor container 10 and the boric acid water is always filled in the reactor container 10. However, in the second embodiment, the water pit for refueling 35 is not provided at the bottom of the reactor container 10. Instead of the water pit for refueling 35, a water tank for refueling 205 is provided on the outside of the reactor container 10. The pH adjusting system 201 according to the second embodiment is specifically explained below. This pH adjusting system 201 includes the reactor container 10 that stores the nuclear reactor 5, the water tank 205 provided on the outside of the reactor container 10, a spray facility 206 that can spray boric acid water stored in the water tank for refueling 205 into the reactor container 10, and the pH adjusting apparatus 37 for adjusting pH in the reactor container 10. The reactor container 10 is configured to be capable of storing the boric acid water at the bottom thereof. Usually, the bottom of the reactor container 10 is in an empty state (see FIG. 6). However, at abnormal time of the nuclear reactor 5, the bottom of the reactor container 10 is filled with the boric acid water sprayed by the spray facility 206 (see FIG. 7). Therefore, the bottom of the reactor container 10 functions as an internal water storage tank that stores the boric acid water at abnormal time. The water tank for refueling 205 stores the boric acid water in the inside thereof. Usually, the boric acid water is used in refueling the fuel assemblies 15. However, at abnormal time of the nuclear reactor 5, the boric acid water is also used as cooling water for cooling the inside of the reactor container 10. The spray facility 206 includes four spray rings 207 (one is shown in the figure), a first spray pipe 208 that connects the four spray rings 207 and the water tank for refueling 205, a spray pump 209 interposed in the first spray pipe 208 on the outside of the reactor container 10, a second spray pipe 210 that connects the first spray pipe 208 between the water tank for refueling 205 and the spray pump 209 and the bottom of the reactor container 10, and a duct switching valve 211 disposed in a connecting portion of the first spray pipe 208 and the second spray pipe 210. When the spray facility 206 operates at abnormal time, first, the spray pump 209 is driven to supply the boric acid water from the water tank for refueling 205 to the spray rings 207. At this point, the duct switching valve 211 switches a duct to lead from the water tank for refueling 205 to the spray rings 207. When the boric acid water is sprayed into the reactor container 10 from the spray ring 207, the sprayed boric acid water flows to the bottom of the reactor container 10. Consequently, the bottom of the reactor container 10 is gradually filled with the boric acid water and a water level thereof rises. When the water level in the water tank for refueling 205 reaches a level equal to or lower than a predetermined water level, the duct switching valve 211 switches the duct to lead from the bottom of the reactor container 10 to the spray rings 207. Then, the spray pump 209 supplies the boric acid water stored at the bottom of the reactor container 10 to the spray rings 207 and circulates the boric acid water in the reactor container 10. The pH adjusting apparatus 37 is configured in the same manner as the pH adjusting apparatus 37 according to the first embodiment and disposed on the inspection rack 42 provided in the reactor container 10. In other words, the pH adjusting apparatus 37 is disposed right below the spray ring 207 and disposed above the bottom of the reactor container 10 that functions as an internal water storage tank. When the spray facility 206 operates at abnormal time, the boric aid water is sprayed from the spray rings 207 and the sprayed boric acid water falls on the pH adjusting apparatus 37. When the boric acid water is sprayed on the pH adjusting apparatus 37, the boric acid water flows into the basket housing container 51 and the basket 50 is submerged in the boric acid water. The pH-adjusted solution is generated by the pH adjusting apparatus 37 and the generated pH-adjusted solution flows into the bottom of the reactor container 10. Consequently, even when there is no space for disposing the pH adjusting apparatus 37 at the bottom of the reactor container 10, by adopting the above configuration, it is possible to dispose the pH adjusting apparatus 37 above a water level of the boric acid water filled at the bottom of the reactor container 10 while suitably performing adjustment of pH in the reactor container 10. In the embodiment described above, the pH adjusting apparatus 37 includes the pH adjuster, the basket 50, the basket housing container 51, and the like. However, the present invention is not limited to this. The pH adjusting apparatus 37 only has to be configured to dissolve the pH adjuster stored therein with the boric acid water to generate a pH-adjusted solution and cause the generated pH-adjusted solution to flow into the water pit for refueling 35 (the bottom of the reactor container). The nuclear power plant 1 to which a pH adjusting system 301 according to a third embodiment is applied is explained referring to FIG. 8. In this case, as in the above case, to avoid a redundant description, only sections different from those explained above are explained. FIG. 8 is a schematic diagram of a pH adjusting system according to the third embodiment. In the first embodiment, injection of the boric acid water into the pH adjusting apparatus 37 is performed by the spray facility 36. However, in the third embodiment, injection of the boric acid water into the pH adjusting apparatus 37 is performed by a water filling facility 305 (solvent injecting means) instead of the spray facility 36. The pH adjusting system 301 according to the third embodiment includes the water filling facility 305 that injects the boric acid water into the pH adjusting apparatus 37. The water filling facility 305 has an injection nozzle 307 for injecting the boric acid water into the pH adjusting apparatus 37, a water filling pipe 308 that connects the injection nozzle 307 and the water pit for refueling 35, and an ECCS pump 309 interposed in the water filling pipe 308. The ECCS pump 309 is used in a reactor core system for emergency and supplies the boric acid water to the primary cooling system 3. When an abnormal situation occurs and the water filling facility 305 operates, the ECCS pump 309 is driven to pump up the boric acid water from the water pit for refueling 35 and inject the pumped-up boric acid water into the pH adjusting apparatus 37 via the injection nozzle 307. When the boric acid water is injected into the pH adjusting apparatus 37, because the basket 50 is submerged in the boric acid water, the pH-adjusted solution is generated. The generated pH-adjusted solution flows into the water pit for refueling 35. In the configuration described above, as in the first embodiment, the pH adjusting apparatus 37 can be configured to be capable of generating the pH-adjusted solution at abnormal time and cause the generated pH-adjusted solution to flow into the water pit for refueling 35 below the pH adjusting apparatus 37. Consequently, it is possible to dispose the pH adjusting apparatus 37 above the water pit for refueling 35. Unlike the first embodiment, it is unnecessary to dispose the pH adjusting apparatus 37 right below the spray ring 45d. Therefore, the pH adjusting apparatus 37 can be disposed in an arbitrary position without being restricted by a disposition position of the spray ring 45d. In this case, an upper part of the basket housing container 51 can be opened or can be closed by a lid. A modification of the pH adjusting system 301 according to the third embodiment is explained referring to FIG. 9. FIG. 9 is a schematic diagram of a pH adjusting system according to the modification of the third embodiment. In the third embodiment, the boric acid water is injected into the pH adjusting apparatus 37 by the ECCS pump 309. In the modification, the boric acid water is injected into the pH adjusting apparatus 37 by an exclusive water filling pump 401 separate from the ECCS pump 309. The water filling facility 305 of the pH adjusting system 301 according to the modification of the third embodiment has the injection nozzle 307 for injecting the boric acid water into the pH adjusting apparatus 37, the water filling pipe 308 that connects the injection nozzle 307 and the water pit for refueling 35, and the water filling pump 401 interposed in the water filling pipe 308. In the configuration described above, as in the first and third embodiments, the pH adjusting apparatus 37 can be configured to be capable of generating the pH-adjusted solution at abnormal time and cause the generated pH-adjusted solution to flow into the water pit for refueling 35 below the pH adjusting apparatus 37. As described above, the pH adjusting system and the pH adjusting method according to the present invention is suitable for adjusting pH in a reactor container at abnormal time of a nuclear reactor stored in the reactor container.
041561465	summary	BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a structure for replacably mounting an operating member, such as glove, bag, filter, or the like in a wall port of a radiation shielding box. 2. Detailed Description of the Prior Art In the case where a radioactive or other hazardous material must be indirectly handled or manipulated, such a material is placed in a shielded container, room or box and is handled by means of a glove, a bag, a filter, etc. Heretofore, when it is required to handle or manipulate a shielded material in a shielding box, a transparent shielding box 1, as shown in FIG. 1, was employed. The outside of the box 1 is sealed. On the walls 2 of the box 1, there are provided gloves 3 into which the operator's hands can be put so that his hands can be inserted into the box 1. A bag of polyvinyl chloride 4 is for material to be inserted into or removed from the box, and a filter 5 for filtering polluted material is included in the shielding box. Such a shielding box as described above is well known in the art. The box is provided with ports for securing the gloves and the bag. The construction of these ports will be described. As is shown in FIG. 2 and FIG. 3, a cylindrical fixed port 8 is fixedly inserted into an opening of the wall 2 through a ring-shaped packing 7 whose section is in the form of the letter "U". The base 9 of the glove 3 is placed over the outer wall of the fixed port and is tightly clamped with clamping parts, or an "O" ring 10 and a tightened sealing band 11. With the shielding box thus constructed, an old glove is replaced by a new glove in accordance with the following method: First, the fingers of the new glove 12 are inserted into the old glove 3. Then, a sealing tool 18 consisting of disk-shaped steel plates 13 and 14, a cylindrical rubber section 15, and a screw member 17 with a handle 16 is inserted into the new glove 12. The rubber section 15 is inflated by operating the handle 15 as shown with the dotted line in FIG. 2, so that parts of the new and old gloves 12 and 3 are abutted against the inner wall of the fixed port 8 thereby to seal the box 1 from the outside. Then, the tightening band 11 is removed from the fixed port and the base 9 of the old glove 3 is folded about the "O" ring 10. In this operation, a slight amount of polluted material may be transferred to the surface of the base portion of the glove thus folded and to the outer wall of the fixed port 8. This polluted material must be completely removed from such parts. Then, although not shown in the drawing, the base 19 of the new glove 12 is pulled over the base 9 of the old glove 3 folded and is placed on the periphery of the fixed port 8. Thereafter, the base 19 of the new glove thus placed is secured to the outer wall of the fixed port 8 with the tightening band 11. Then, the sealing tool 18 is released by operating the handle 16, and the old glove 3 is caught through the new glove 12 by the band so that the old glove 3 together with the "O" ring 10 is pulled into the box 1 and is allowed to drop therein. Finally, a new "O" ring is placed on the base 19 of the new glove. Thus the replacement of the old glove with the new glove has been completed. In the case when an unnecessary material 20 is removed from the box 1, the material 20 is put in the bag as shown in FIG. 3, and a suitable part 21 of the bag 4 above the material 20 is sealed and then cut off to take the material 20 out of the box as shown in FIG. 4. In contrast, if it is necessary to put a material 22 into the bag 4 from outside, a suitable part 25 of the bag is sealed as shown in FIG. 5. Then the material 22 is, put into the box 1 through the hole 24 of a port section 23, and the part 25 thus sealed is cut off inside the box 1. As the removal or insertion of the material is frequently carried out, it will be required to replace the bag 4 with a new one. In this case, of course, the old bag 4 is removed from the port section 23. As is apparent from FIGS. 3 through 5, the conventional bag mounting structure is such that the bag is fixedly secured directly to the port section 23 with the tightening band 11 and the "O" ring 10. Accordingly, the replacement of the bag 4 is carried out by the use of the sealing tool 18, similarly as in the replacement of the glove 3. Gloves 3 and the bags 4 are also provided at places on the wall of the box 1 in view of various internal conditions, where normally the glove or the bag is not used. However, these gloves and bags will be deteriorated with the lapse of time and must be replaced with new ones some time. The filter 5 is not concretely illustrated; however, the replacement of the filter will become apparent from the following description: The filter 5 is inserted into a filter fixing frame provided on the wall 2 of the shielding box 1, and a retainer is placed over the filter thus inserted, at the outside of the shielding box 1. Thus, the provision of the filter 5 is completed. When the filter 5 should be replaced with a new one owing to the decrease of its filtering capacity or its pollution, the replacement of the filter is carried out by removing or opening the retainer. However, in the above-described port sections of the glove and the filter, a part of the polluted material may leak out of the shielding box 1 during the replacement operation. Therefore, the conventional method is not completely safe. Furthermore, the conventional method is not economical because the replacement requires a special tool and the gloves are often wasted. In addition, it is rather troublesome to periodically inspect a number of gloves, which are not used so often, for damage or deterioration, which leads to the necessity of a great deal of labor. Known in the art is an arrangement in which air supplying ducts (pipes) 27 for introducing clean air into the boxes 1 in order to clean the atmosphere in the boxes and exhaust ducts 28 for discharging the polluted air out of the boxes 1 are connected to the respective boxes 1, as shown in FIG. 6. In the midpoint of the exhaust duct 28, a filter case 30 including a filter 29 is connected through rubber tubes 31 and 32, so that the polluted air is discharged out of the box 1 through a stack 26. When the used filter is replaced with a new one, it is essential that the worker should not directly touch the polluted filter. Therefore, the replacement of the polluted filter 29 is carried as follows. First, the rubber tubes 31 and 32 are sealed to block the flow of air therein, and the duct mouths 33 and 34 of the polluted filter case 30 are removed from the respective rubber tubes 31 and 32 thereby to remove the filter case 30. Then, the duct mouths of a new filter case are respectively coupled to the ends of the ends of the sealed rubber tubes 31 and 33. Thus, the replacement of the polluted filter case has been completed. In the case where a large volume of polluted air should be cleaned, it goes without saying that the use of only one filter case is insufficient, and a number of filter cases. as shown in FIG. 7, must be disposed horizontally or vertically. Accordingly, in the replacement of these number of filter cases, the worker must move back and forth or up and down. Furthermore, the replacement of the filter cases should be done within as short a period of time as possible in view of the worker's health. However, according to the conventional replacement method, it takes a lot of time to complete the replacement, and the polluted air might leak out. SUMMARY OF THE INVENTION Accordingly, an object of this invention is to provide an improved port section in which all of the above-described drawbacks have been eliminated, and polluted material is scarecely leaked out of a shielding box. According to the invention, a port section structure comprises a cylindrical fixed port on a wall of a shielding box, a cylindrical replacement port having an operating member and screwed into said fixed port, and an elastic member inserted in a compressed and deformed state between the fixed port and the replacement port. According to another aspect of this invention, the cylindrical replacement port having an operating member includes a concave section and/or a convex section provided in at least one end face of the replacement port so as to be able to engage with a convex section and/or a concave section provided in another replacement port.
047160128	claims	1. In combination, an upright cylindrical nuclear reactor pressure vessel having a hemispherical lower head section with a curved inner surface and defining an annular flange extending radially inward near its upper end, reactor internals suspended within said pressure vessel from said flange, said internals extending downward into said hemispherical lower head section but with the lower end thereof terminating short of contacting the curved inner surface hemispherical lower head section to form a radially extending, annular gap therebetween which varies in size in response to variations in the temperature of reactor coolant circulated through the pressure vessel and internals due to a difference in the coefficients of thermal expansion thereof, and strainer means comprising an annular member with apertures therethrough smaller than the smallest size of said gap secured to the lower end of said reactor internals and extending radially outward therefrom, over the gap with an outer peripheral edge in contact with the curved inner surface of the hemispherical lower head section for all sizes of said gap to prevent debris from entering and lodging in said gap from above while allowing fluid to pass therethrough. 2. The combination of claim 1 wherein said annular strainer member is a resilient member which is fixed to the lower end of said internals with said outer peripheral edge pressed against the hemispherical lower head section of the vessel and which bends to maintain said outer peripheral edge in contact with the curved inner surface of the hemispherical lower head section of the vessel as the size of the gap changes. 3. The combination of claim 2 wherein said annular strainer member is curved in cross-section with a curvature which maintains said outer peripheral edge of the resilient annular member in contact with the inner surface of the hemispherical lower head section as the gap varies in size. 4. The combination of claim 3 wherein said annular member is convex upward in cross-section to increase over a flat annular member the angle at which the strainer member intersects the curved inner surface of the hemispherical lower head section of the vessel. 5. A nuclear reactor comprising: an upright cylindrical pressure vessel having a hemispherical lower head section with a curved inner surface and defining an annular support flange extending radially inward near the upper end thereof; a cylindrical core barrel having a radially outwardly extending flange at its upper end which seats on said support flange with the core barrel suspended inside the pressure vessel; resilient means clamping said core barrel flange down onto said support flange; secondary core support means depending from the bottom of the core barrel into the lower hemispherical head section and terminating at its lower end in a horizontally extending base plate which defines at its lower edges a spherical surface spaced from the inner surface of the hemispherical lower head section to define a radially extending, annular gap therebetween; and strainer means for preventing debris from entering from above and lodging in said gap and lifting the flange on said core barrel up off of the support flange against said resilient clamping means as the core barrel and secondary core support expand more than the pressure vessel in response to heat-up of the reactor to reduce the size of said gap, said strainer means comprising an upwardly convex in cross-section, resilient, annular, member secured to the periphery of said base plate and extending radially outward therefrom over said gap to contact with a peripheral edge the inner curved surface of the hemispherical lower head section, and which bends to remain in contact therewith as said gap varies in size with temperature, said annular member defining apertures therethrough through which reactor coolant but not debris of a size which could lodge in said gap can pass into said gap from above.
	description	This application claims priority to U.S. provisional patent application No. 62/698,540 filed Jul. 16, 2018, the disclosure of which is incorporated by reference herein. The presently-disclosed invention relates generally to systems for irradiating radioisotope targets in nuclear reactors and, more specifically, to systems for irradiating radioisotope targets in heavy water-moderated fission-type nuclear reactors. Technetium-99m (Tc-99m) is the most commonly used radioisotope in nuclear medicine (e.g., medical diagnostic imaging). Tc-99m (m is metastable) is typically injected into a patient and, when used with certain equipment, is used to image the patient's internal organs. However, Tc-99m has a half-life of only six (6) hours. As such, readily available sources of Tc-99m are of particular interest and/or need in at least the nuclear medicine field. Given the short half-life of Tc-99m, Tc-99m is typically obtained at the location and/or time of need (e.g., at a pharmacy, hospital, etc.) via a Mo-99/Tc-99m generator. Mo-99/Tc-99m generators are devices used to extract the metastable isotope of technetium (i.e., Tc-99m) from a source of decaying molybdenum-99 (Mo-99) by passing saline through the Mo-99 material. Mo-99 is unstable and decays with a 66-hour half-life to Tc-99m. Mo-99 is typically produced in a high-flux nuclear reactor from the irradiation of highly-enriched uranium targets (93% Uranium-235) and shipped to Mo-99/Tc-99m generator manufacturing sites after subsequent processing steps to reduce the Mo-99 to a usable form, such as titanium-molybdate-99 (Ti—Mo99). Mo-99/Tc-99m generators are then distributed from these centralized locations to hospitals and pharmacies throughout the country. Since Mo-99 has a short half-life and the number of existing production sites are limited, it is desirable both to minimize the amount of time needed to reduce the irradiated Mo-99 material to a useable form and to increase the number of sites at which the irradiation process can occur. There at least remains a need, therefore, for a system and a process for producing a titanium-molybdate-99 material suitable for use in Tc-99m generators in a timely manner. One embodiment of the present disclosure provides a target irradiation system for irradiating a radioisotope target in a vessel penetration of a fission reactor, the system including an irradiated target removal system with a body defining a central bore, an elevator that is configured to be selectively received within the central bore, and a docking surface that is configured to selectively place the irradiated target removal system in fluid communication with the vessel penetration. A target canister includes a body defining a target bore that is configured to slidably receive the radioisotope target therein and a cap configured to attach to the body of the target canister, thereby providing a water-tight seal for the target bore. The elevator is configured to receive the target canister therein and is lowered into the vessel penetration of the reactor when irradiating the radioisotope target. The irradiated target removal system forms a portion of a pressure boundary of the reactor when in fluid communication with the vessel penetration. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more embodiments of the invention and, together with the description, serve to explain the principles of the invention. Repeat use of reference characters in the present specification and drawings is intended to represent same or analogous features or elements of the invention according to the disclosure. The invention now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all, embodiments of the invention are shown. Indeed, this invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. As used in the specification, and in the appended claims, the singular forms “a”, “an”, “the”, include plural referents unless the context clearly dictates otherwise. Referring now to the figures, a target irradiation system in accordance with the present disclosure includes an adjuster port docking pedestal 150 (FIGS. 1A through 1C) that is in fluid communication with a vessel penetration of a corresponding nuclear reactor, an irradiation target removal system 100 (FIG. 3A) that is selectively dockable with adjuster port docking pedestal 150 so that the irradiation target removal system 100 may insert into and extract irradiation targets 145 (FIG. 4) from the nuclear reactor, respectively, at least one target canister 140 (FIG. 4) for housing radioisotope targets 145 during irradiation, and an irradiated material transfer flask 180 (FIG. 8) including a target exchange module 190 (FIG. 8) disposed therein for the loading and unloading of target canisters 140. Referring additionally to FIG. 2, adjuster port docking pedestal 150 is preferably mounted to a reactivity mechanism deck 103 of a corresponding heavy water moderated nuclear fission reactor 101 (such as a CANDU (CANada Deuterium Uranium) reactor shown in FIGS. 10 and 12A through 12C), so that adjuster port docking pedestal 150 is in fluid communication with an unused adjuster port 105 (FIG. 12B) of the reactor. Note, however, in alternate embodiments various other types of reactors and vessel penetrations may be utilized during the radioisotope target irradiation process. Referring now on the FIGS. 1A through 1C, adjuster port docking pedestal 150 includes an outer body portion 152 defining a central cavity in which an inner body portion 163 is disposed. Outer body 152 includes a plurality of support legs 156 extending radially-outwardly therefrom, each support leg 156 including an outrigger 162 with a socket 158 and corresponding lag bolts 160 disposed at its lower end. Each socket 158 is configured to be received in a corresponding mounting aperture of reactor reactivity mechanism deck 103 (FIG. 2), and lag bolts 160 are used to semi-permanently secure adjuster port docking pedestal 150 to the reactivity mechanism deck. Preferably, outer body 152 is formed of depleted uranium, thereby providing radiation shielding. Inner body portion 163 of adjuster port docking pedestal 150 includes central bore 164 that is in fluid communication with the interior of reactor vessel 113 by way of the corresponding adjuster port, a mounting flange 166 that is configured to be secured to the corresponding adjuster port, and a gate valve 172 disposed at the upper end of inner body portion 163. Gate valve 172 includes a motor 174 for remote operation of a gate 175 (not shown in FIG. 1C) and provides a docking surface 176 so that an irradiated target removal system 100 (FIG. 3A) may be selectively secured to adjuster port docking pedestal 150, as discussed in greater detail below. Gate valve 172 provides a seal so that adjuster port docking pedestal 150 forms a portion of the reactor's pressure boundary when the gate valve is closed. A maintenance control valve 168 is also provided for pressure boundary isolation should maintenance be required on gate valve 172. Additionally, a force isolation bellows 170 is provided to lessen contact forces between irradiated target removal system 100 and adjuster port docking pedestal 150 during docking procedures, as discussed in greater detail below. Referring now to FIGS. 3A through 3D, irradiated target removal system 100 includes a body 102 defining an elongated central bore 104, an elevator 112 that is selectively receivable within central bore 104, a winch 106 that is connected to elevator 112 by cable 110 that passes over a pulley 108, and a gate valve 132 that is disposed on the bottom of irradiated target removal system 100. As best seen in FIG. 3B, elevator 112 includes a pair of opposed risers 116 that have a plurality of support platforms 122 extending therebetween. Each support platform is configured to slideably receive a corresponding target canister 140 thereon, as shown in FIG. 3A. Elongated protrusions 118 are disposed on the inner surfaces of both risers 116 and are configured to engage correspondingly shaped elongated grooves 147 on each target canister 140 (FIG. 4) to help maintain the target canisters in the desired positions on elevator 112. A connection point 114 is disposed at the top end of elevator 112 and is configured to be crimped to the bottom end of cable 110. Elevator 112 includes a V-shaped bottom surface 124 to facilitate proper alignment of elevator 112 within target exchange module 190 (FIG. 9) for the loading and unloading of target canisters 140, as discussed in greater detail below. The apexes of V-shaped bottom surface 124 each correspond to an elongated groove 120 formed on an outer surface of each riser 116, as also discussed in greater detail below. Irradiated target removal system 100 also includes a damped lift assembly 126 disposed on its upper end. Damped lift assembly 126 includes a shackle 128 to facilitate lifting by the reactor's crane 107 (FIG. 10), and is configured to lessen contact forces between irradiated target removal system 100 and adjuster port docking pedestal 150 during docking procedures. Preferably, a purging/drying tank 130 is provided for removing moderator water from the interior of irradiated target removal system 100 after the irradiation process is complete. The drying process is performed prior to shutting gate valve 132 and subsequently undocking irradiated target removal system 100 from adjuster port docking pedestal 150. Similarly to the gate valve of adjuster port docking pedestal 150, gate valve 132 includes a motor 134 for remote operation of a gate (not shown in FIG. 1C), and its bottom surface is a docking surface 136 for mating with docking surface 176 of adjuster port docking pedestal 150, as shown in FIG. 6. Referring now to FIG. 4, target canister 140 includes a substantially cylindrical body portion 142 including a pair of opposed, parallel sidewalls 143. A plurality of target bores 144 is defined by target canister 140, each target bore 144 being parallel to a longitudinal center axis of target canister 140, and configured to slideably receive a corresponding radioisotope target 145 therein. A sealing cap 146 is connectable to the end of target canister 140 from which target bores 144 extend so that the interior of target canister 140 remains free of fluids during the irradiation process. A first pair of recesses 148 and a second pair of recesses 149 are formed on opposite sides of each sidewall 143 and are configured to be selectively engaged by corresponding gripper pins of target exchange module 190 (FIG. 9) during loading and unloading operations, as discussed in greater detail below. As well, each sidewall 143 includes an elongated groove 147 that is configured to selectively receive a corresponding elongated protrusion 118 formed on the inner surface of the elevator's risers 116 (FIG. 3B) to help retain each target canister 140 on elevator 112, as shown in FIG. 5. Referring now to FIGS. 7A, 7B and 8, irradiated material transfer flask 180 includes a body 182 defining a central bore 184, a target exchange module 190 disposed within central bore 184, and an in-station transfer tool 186 mounted to a top end of body 182. During loading and unloading operations, irradiated target removal system 100 is docked with in-station transfer tool 186, as shown in FIG. 7B. In-station transfer tool 186 provides the required pneumatic/electrical connections to facilitate the loading and unloading of target canisters 140, and its upper surface forms a docking surface 188 that is configured to mate with docking surface 136 of irradiated target removal system 100. Once irradiated target removal system 100 is securely docked with irradiated material transfer flask 180, gate valve 132 of irradiated target removal system 100 is opened and elevator 112 is lowered into central bore 184 so that target canisters 140 may be loaded and/or unloaded by target exchange module 190. Note, as shown in FIGS. 7A and 7B, irradiated material transfer flask 180 is disposed atop a cradle 185 that facilitates movement of irradiated material transfer flask 180 by a forklift 111 (FIGS. 10 and 11) in a loading area 109 of the reactor facility. Referring now to FIG. 9, target exchange module 190 includes a frame 192 defining a central passage 197 and first and second storage locations 199a and 199b, respectively, disposed on opposite sides of central passage 197. Central passage 197 is configured to allow elevator 112 of irradiated target removal system 100 to pass through target exchange module 190 so that the desired target canister 140 of the elevator may be aligned with a pair of gripper slides 194 of target exchange module 190. As shown in FIG. 9, each gripper slide 194 includes a first pair of gripper pins 196 and a second pair of gripper pins 198, wherein each pair of gripper pins is configured to selectively engage a corresponding pair of recesses 148 and 149 of target canister. Interaction between the gripper pins and the gripper recesses allows gripper slides 194 to move target canisters 140 both onto and off of elevator 112. Moreover, gripper pins 196 and 198 may remain engaged with the corresponding recesses 148 and 149 of the target canisters during movement of irradiated material transfer flask 180 to help stabilize them. Each gripper slide 194 includes a piston 191 for moving the slide transversely along a pair of linear bearings 193. Referring still to FIG. 9, target exchange module 190 includes a pair of rotary guide pins 195, the rotary guide pins being disposed opposite each other and adjacent central passage 197. Each rotary guide pin 195 extends radially inwardly into central passage 197 and is configured to engage the outer periphery of V-shaped bottom surface 124 of elevator 112 as the elevator is lowered into central passage 197 of target exchange module 190. As elevator 112 is lowered into central passage 197, each rotary guide pin 195 comes into contact with a corresponding portion of V-shaped bottom surface 124. If rotary guide pins 195 are aligned with apexes 125 of V-shaped bottom surface 124, each rotary guide pin 195 will slideably enter a corresponding one of the elongated grooves 120, each of which originates at a corresponding apex 125 of the bottom surface and elevator 112. As such, the elevator will pass through target exchange module 190 without rotation. However, if rotary guide pins 195 make contact with V-shaped bottom surface 124 anywhere other than apexes 125, elevator 112 will be caused to rotate as the periphery of the bottom surface passes along rotary guide pins 195. When rotary guide pins 195 reach apexes 125, rotation will stop and rotary guide pins 195 will slideably pass through the corresponding elongated grooves until elevator 112 reaches the desired position. Referring now to FIGS. 13A and 13B, an alternate embodiment of a target irradiation system in accordance with the present disclosure is shown. The alternate embodiment differs primarily from the previously discussed embodiment in that adjuster port docking pedestal 250 includes a winch 256 and pulley 258 for raising and lowering an elevator. Similarly to the previous discussed embodiment, after irradiated target removal system 200 is docked to adjuster port docking pedestal 250, gate valves 232 and 272 are opened and elevator 212 may be lowered into the adjuster port docking pedestal 250, which is in fluid communication with corresponding adjuster port 105 (FIGS. 12B and 12C). However, unlike the previous embodiment, once in the adjuster port docking pedestal 250, elevator 212 is transferred to winch 256 and pulley 258 for further lowering into the adjuster port. After elevator 212 is transferred to winch 256, gate valves 232 and 272 are closed so that irradiated target removal system 200 no longer forms a portion of the pressure boundary of the reactor. As such, irradiated target removal system 200 can be un-docked from adjuster port docking pedestal 250 and removed for the duration of the irradiation process. Note, the target irradiation system shown in FIGS. 13A and 13B also differs from the previous embodiment in that irradiated target removal system 200 includes an onboard target exchange module 290 for the loading and unloading target canisters 140. As shown in FIG. 14, yet another embodiment of a target irradiation system includes an irradiated target removal system 300 that is supported by a bridge 113 when positioned over the adjuster port docking pedestal 150 and reactivity mechanism deck 103 as targets are irradiated. The support provided by bridge 113 lessens the weight supported by the adjuster port docking pedestal and also limits the number of moves required by crane 107 over the reactivity mechanism deck to properly position irradiation target removal system 300. These and other modifications and variations to the invention may be practiced by those of ordinary skill in the art without departing from the spirit and scope of the invention, which is more particularly set forth in the appended claims. In addition, it should be understood that aspects of the various embodiments may be interchanged in whole or in part. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only, and it is not intended to limit the invention as further described in such appended claims. Therefore, the spirit and scope of the appended claims should not be limited to the exemplary description of the versions contained herein.
042723205	summary	This invention relates to targets for implosion by an energy source, such as one or more laser beams, and more particularly to a high density laser-driven target. In recent years much effort has been directed to inertial confinement fusion systems wherein a target is imploded by an energy source such as a laser or electron beam machine. U.S. Pat. No. 3,378,446 issued Apr. 16, 1968 to J. R. B. Whittlesey; 3,489,645 issued Jan. 13, 1970 to J. W. Daiber et al; 3,624,239 issued Nov. 30, 1971 to A. P. Fraas; 3,723,246 issued Mar. 27, 1973 to M. J. Lubin; and 3,762,992 issued Oct. 2, 1973 to J. C. Hedstrom are exemplary of these inertial confinement systems. As set forth in U.S. Pat. No. 3,723,246 to M. J. Lubin inertial confinement fusion has various utilities recognized by the scientific community as excellent sources of neutrons, x-rays, alpha particles, for example, for applications in radiography, synthetic fuel production, fissile fuel production, as well as for physics studies. The advent of inertial confinement fusion wherein a tiny fusion fuel target can be imploded in an evacuated chamber without damage to the chamber or the optics involved has provided an excellent source of neutrons, etc., at a magnitude not previously available under controlled conditions. Thus, as widely recognized by the scientific community, while fusion power for electrical production has not yet been accomplished, the inertial confinement fusion techniques thus far developed have greatly advanced the state of the art. In addition to the systems of the above-referenced U.S. Patents, various inertial confinement fusion mechanisms for imploding the targets have been developed as exemplified by U.S. Pat. No. 4,017,163 issued Apr. 12, 1977, to A. J. Glass, and articles "Laser Fusion Target Illumination System" by C. E. Thomas, Applied Optics, Vol. 14, No. 6, June 1975; and "Thermonuclear Fusion Research With High-Power Lasers", Vacuum Technology, May 1975, pp 50-60 and 64, by R. R. Johnson et al. Various target designs have been proposed in the open literature for laser, electron beam, and ion beam implosion techniques as exemplified by Report UCID-17297 "A 1964 Computer Run On A Laser-Imploded Capsule", by R. E. Kidder, Mar. 28, 1973; "Implosion, Stability, And Burn Of Multishell Fusion Targets" By G. S. Fraley et al, The Fifth I.A.E.A Conference on Plasma Physics and Controlled Nuclear Fusion Research, Tokyo, Japan, Nov. 11-15, 1974 as Paper IAEA-CN-33/F55 (LA-UR-5783-MS); "Laser Driven Implosion of Hollow Pellets" by J. Nuckolls et al, presented at the above-referenced Fifth I.A.E.A. Conference (UCRL-75538); "Structured Fusion Target Designs" by R. C. Kirkpatrick et al, Nuclear Fusion 15, April 1975, pp. 333-335; "Target Compression With One Beam" by G. H. McCall et al, Laser Focus, Dec. 1974, pp. 40-43; "Electrically Imploded Cylindrical Fusion Targets" by W. S. Varnum, Nuclear Fusion 15, Dec. 1975, pp. 1183-1184; "The Calculated Performance Of Structured Laser Fusion Pellets" by R. J. Mason, Nuclear Fusion 15, Dec. 1975, pp. 1031-1043; "Low Power Multiple Shell Fusion Targets For Use With Electron And Ion Beams" by J. D. Lindl et al and "Stability and Symmetry Requirements of Electron and Ion Beam Fusion Targets" by R. O. Bangerter et al, both published in the Proceedings of the International Topical Conference on Electron Beam Research and Technology held Nov. 3-6, 1975, Albuquerque, N. M. (Printed Feb. 1976), SAND76-57122; and "Problems With Fuel Pellets For Laser-Induced Fusion", Physics Today, March 1975, pp. 17 and 20. The production of fusion neutrons by inertial confinement (laser implosion) techniques was first demonstrated in May 1974, see above-referenced Vacuum Technology article by R. R. Johnson, and "Measurement of the Ion Temperature in Laser-Driven Fusion" by V. W. Slivinsky et al, Physical Review Letters, Vol. 35, No. 16, Oct. 20, 1975, pp. 1083-1085. Since that time hundreds of targets of various configurations have been imploded by lasers and electron beam machines which have verified to the satisfaction of the scientific community that neutrons are being produced from fusion reactions. Diagnostic techniques for verifying this fact are exemplified by the above-cited Physical Review-Letters by V. W. Slivinsky et al; "Pinhole imaging of Laser-Produced Thermonuclear Alpha Particles" by V. W. Slivinsky et al, Applied Physics Letters, Vol. 30, No. 11, June. 1, 1977, pp. 555-556; "Laser-Fusion Ion Temperatures Determined by Neutron Time-Of-Flight Techniques" by R. A. Lerche et al, UCRL-79375, dated April 1977; and "Implosion Experiments With D,He.sup.3 Filled Microballons" by V. M. Slivinsky et al, UCRL-78450 Rev. II, dated Mar. 11, 1977. Such diagnostics have verified that the computer code "LASNEX", for example, accurately models current laser fusion experiments. Target fabrication techniques are at an advanced state of development with numerous mechanisms and processes having been developed, as exemplified by the above-referenced U.S. Pat. No. 3,723,246 to M. J. Lubin, and U.S. Pat. No. 3,907,477, issued Sept. 23, 1975 to T. R. Jarboe et al; No. 3,985,841 issued Oct. 12, 1976 to R. J. Turnbull et al; and No. 4,012,265 issued Mar. 15, 1977 to J. A. Rinde et al. Copending U.S. Patent Application Ser. No. 609,640 filed Sept. 2, 1975, now U.S. Pat. No. 4,035,032 issued July 5, 1977, and Ser. No. 807,108, filed June 16, 1977, now U.S. Pat. No. 4,133,854 issued Jan. 9, 1979, each in the name of C. D. Hendricks, assigned to the assignee of this application, describe and claim processes for rapidly producing fusion target. In addition numerous publications such as "Spherical Hydrogen Targets for Laser-Produced Fusion" by I. Lewkowicz, J. Phys. D: Appl. Phys., Vol. 7, 1974; "Fabrication and Characterization of Laser Fusion Targets" by C. D. Hendricks et al, American Physical Society, Division of Plasma Physics, Nov. 10-14, 1975 (UCRL-76679); and report UCRL-50021-75"Laser Program Annual Report 1975", Lawrence Livermore Laboratory, Univ. of Calif., Section 7 "Target Fabricartion", distributed Nov. 1976, pp. 343-368. Thus, while commercial fusion power reactors may be at least a decade away, the inertial confinement fusion technology has raidly advanced such that greater than 10.sup.9 fusion neutrons are being produced by existing implosion systems, which systems currently provide an excellent source of neutrons, x-rays, alpha particles, etc., which sources have not been previously available, in the magnitude now provided, to the scientific community for use in various recognized applications as exemplified above. In addition, other currently known applications for neutrons, x-rays etc., produced by the target of this invention have applications in the field of neutron crystallography, means of achieving crystal dislocation, initiation of some action such as a switch or random number generator upon receipt of a neutron pulse by a detector, calibration of diagnostics for other apparatus, fluor studies, and as a source of strong shock waves for high pressure testing. With the acceptance by the scientific community that fusion neutrons have been produced by laser imploded targets, substantial effort is now being directed toward large laser systems and a prototype inertial confinement fusion reactor. As laser capabilities increase, targets capable of producing high neutron, x-ray yield must be developed, and with, for example, the 20-beam Shiva laser system targets having high densities will be utilized to increase the yield. While laser systems prior to Shiva have been capable of attaining high fuel densities or temperatures, but not both, the higher power Shiva system will be able to increase both the fuel densities and temperatures. Thus, a need exists for a high density laser-driven target. SUMMARY OF THE INVENTION The present invention is a high density target for inertial confinement fusion applications, and is particularly applicable for implosion by high energy lasers. Basically the target is composed of a quantity of fusion fuel surrounded by a pusher shell and having an ablator-pusher shell in spaced relation with said pusher shell defining a region therebetween which is filled with low-density material. Therefore, it is an object of this invention to provide a high density target for inertial confinement fusion. A further object of the invention is to provide a high density laser-driven target. Another object of the invention is to provide a target for laser implosion utilizing a double shell geometry wherein the inner shell functions as a pusher and the spaced outer shell functions as an ablator-pusher to implode the inner shell. Other objects of the invention will become readily apparent from the following description and accopanying drawing.
050080695	abstract	A heat-generating member (3), in particular a nuclear reactor core, is placed in a liquid contained in a pressure vessel (1) and adapted to serve as a coolant for the heat-generating member. For cooling of the liquid the pressure vessel is adapted to be included in a circulation system (15a, 15, 14. 16, 16a) for self-circulation of the liquid and/or of steam of the liquid with any contents of uncondensable gas. The circulation system also includes an evaporator (14) arranged in an evaporation pool (13), a supply conduit (15) for conducting liquid and/or steam from a point of connection (15a) in the upper part of the pressure vessel to the evaporator, and a discharge conduit (16) for conducting liquid from the evaporator to a point of connection (16a) on the pressure vessel which is located below the point of connection (15a) for the supply conduit. The evaporator is located at a higher level than the point of connection (16a) on the pressure vessel for the discharge conduit (16). At a level above its bottom (16b) the discharge conduit is connected to a discharge vessel (21) by means of a connecting conduit (20), which only allows a considerably smaller flow than the flow in the circulation system, for discharging uncondensable gas from the circulation system, which discharge vessel (21) is provided with one or more outlets (22a, 22a) for gas and steam for maintaining a lower pressure in the discharge vessel than inside the evaporator.
061817732	summary	TECHNICAL FIELD This invention relates to radiation anti-scatter grids, and more particularly, to a single stroke, moving radiation anti-scatter grid that is a component in a radiographic diagnostic imaging system, specifically a direct radiographic imaging system. BACKGROUND OF THE INVENTION Description of the Art Direct radiographic imaging using detectors comprising a two dimensional array of tiny sensors to capture a radiation generated image is well known in the art. The radiation is imagewise modulated as it passes through an object having varying radiation absorption areas. Information representing an image is, typically, captured as a charge distribution stored in a plurality of charge storage capacitors in individual sensors arrayed in a two dimensional matrix. X-ray images are decreased in contrast by X-rays scattered from objects being imaged. Anti-scatter grids have long been used (Gustov Bucky, U.S. Pat. No. 1,164,987 issued 1915) to absorb the scattered X-rays while passing the primary X-rays. A problem with using grid, however, is that whenever the X-ray detector resolution is comparable or higher than the spacing of the grid, an image artifact from the grid may be seen. Bucky recognized this problem which he solved by moving the anti-scatter grid to eliminate grid image artifacts by blurring the image of the anti-scatter grid (but not of the object, of course). Improvements to the construction of anti-scatter grids have reduced the need to move the grid, thereby simplifying the apparatus and timing between the anti-scatter grid motion and X-ray generator. However, Moire pattern artifacts can be introduced when image capture is accomplished through the direct radiographic process or when film images are digitized. (The Essential Physics of Medical Imaging, Jerrold T Bushberg, J. Anthony Seibert, Edwin M. Leidholdt, Jr., and John M. Boone. c1994 Williams & Wilkins, Baltimore, pg. 162 ff.). When the X-ray detector is composed of a two dimensional array of X-ray sensors, which generate a two dimensional array of picture elements, as opposed to film, the beat between the spatial frequency of the sensors and that of the anti-scatter grid gives rise to an interference pattern having a low spatial frequency, i.e. a Moire pattern. There are two possible approaches to solving this problem. The first, described in U.S. Pat. No. 5,666,395 to Tsukamoto et al. teaches Moire pattern prevention with a static linear grid having a grid pitch that is an integer fraction of the sensor pitch. In the case where the sensors are separated by dead spaces, i.e. interstitial spaces which are insensitive to radiation detection, Tsukamoto teaches to make the grid pitch to correspond to the sensor pitch and to hold in a steady positional relation to the detector such that the grid elements are substantially centered over the interstitial spaces. A problem with the above proposed solution, which uses a static grid, is that it is often impractical to position and to maintain the anti-scatter grid in a desired fixed position relative to the radiation detector array. A second approach, originally proposed by Bucky in U.S. Pat. No. 1,164,987 proposes moving the anti-scatter grid during radiation exposure to blur the artifact images generated by the grid. The use of a moving grid appears a reasonable solution but for one problem. In modem radiographic equipment the exposure time is determined by automated exposure control devices. The total exposure time is, therefore unknown, and as a consequence the bucky must be maintained in motion for an undetermined length of time, at least long enough for the longest anticipated exposure. Using a single stroke unidirectional linear velocity profile is impractical because as the exposure becomes longer the size of the bucky and the length of the bucky path become far too large to be accommodated in a useful package. The solution adopted by the art is to provide an oscillating bucky which can be continuously on for so long as the exposure lasts. While this is an ingenious solution it also presents certain practical problems, particularly related to the direction change in the bucky movement at the two path ends where the grid movement becomes zero prior to reversing direction. A number of patents have issued describing different arrangements to solve this reversal problem including oscillating the grid with a velocity that increases as the grid approaches the travel limits prior to reversal of the travel direction, or controlling the location of the grid interstitial spaces at the reversal point to avoid creation of artifacts. With the exception of the solution proposed by Tsukamoto et al., the above methods have been proposed to solve the problem of a film grid combination rather than direct radiographic imaging application and as such are primarily concerned with the elimination of shadow type artifacts rather than the Moire patterns which are generated when using a direct radiographic detector comprising rows and columns of individual image detecting sensors with an anti-scatter grid. Direct radiography is a relatively new technology and often requires new and different solutions better fitted to the new set of problems associated with it. The art originally started with a grid which was moveable in one direction. When this approach failed, due to innovations in the radiation exposure equipment, the art solved the new problems by inventing the oscillating grid. This solution worked for radiographic film exposure, but does not adequately solve the Moire type problems associated with direct radiography detectors. There is still a need in the art for a single stroke radiation anti-scatter device suitable for a wide range of exposure windows, and tailored to reduce Moire-pattern artifacts in digital radiograms. SUMMARY OF THE INVENTION In accordance with this invention, there is provided a radiation anti-scatter device comprising a grid, and a grid driver connected to the grid for unidirectionaly moving the grid with a variable grid velocity along a path between a starting and an end position. The variable grid velocity may comprise a velocity profile having a decreasing velocity component. The decreasing velocity profile is typically exponential, preferably with V=K.sub.2 t.sup.-m, where V is velocity, K is a constant, t is time, and m is an exponent having a value greater than 0. The initial grid velocity is obtained by first accelerating the grid to a desired velocity. The sole requirement for the increasing velocity component is that the desired maximum velocity for the grid is attained rapidly, preferably within milliseconds. Preferably, maximum velocity is attained within 1 to 10 milliseconds and with a grid displacement between 0.5 and 3 cm. Constant acceleration is preferred as it is easier to implement. The motion may be imparted to the grid by a variable speed motor, a variable drive coupling, or a combination thereof. The anti-scatter device may be part of a direct radiographic diagnostic imaging system further comprising a radiation source for emitting a radiation beam and an image-producing detector comprising an array of radiation sensors positioned in the beam path for receiving the radiation. The system also includes a moveable radiation anti-scatter grid between the radiation source and the detector. The grid is moveable across the image detector with a decelerating velocity profile. The imaging system may further comprise a controller adapted to synchronize the radiation emission with the grid motion. Still according to the present invention, there is provided a method for reducing scattered radiation and eliminating Moire patterns in a radiographic detector by moving an anti-scatter grid over the detector in a single stroke in one direction with a decelerating velocity profile during a radiographic exposure, the decelerating velocity profile being such that the grid motion continues for the duration of the longest anticipated radiation exposure. The method may further comprise starting the radiation exposure at a position in the grid motion optimized for a particular grid, radiation source, or examination procedure.
044329300	claims	1. A method of operating a nuclear reactor comprising: determining the current power density of each core zone; predicting the anticipated reactivity change of each of said core zones after movement of the corresponding reactor coolant displacer elements, based on the equation EQU .DELTA.R=K.times.BU.times.APD determining the reactivity change needed to achieve the desired reactor core power level; selecting an appropriate displacer element for movement to attain the desired reactivity change; and moving said selected displacer element relative to said core for attaining the desired reactor core power level. determining the fraction of the total core power that is attributed to each of said core zones; predicting the anticipated fraction of the total core power that would be attributed to each of said core zones after movement of the corresponding reactor coolant displacer element; and selecting said appropriate displacer element for movement to attain the desired reactivity change without disturbing the total core power distribution. NPD=core zone power density after displacer element movement; OPD=core zone power density prior to displacer element movement; BU=burnup in MWD/MTU; a=a constant; and b=a constant. 2. The method according to claim 1 wherein said method further comprises: 3. The method according to claim 2 wherein said step of predicting the anticipated fraction of the total core power that would be attributed to each of said core zones after movement of the corresponding displacer element comprises predicting said fraction where: EQU NPD=(a+b.times.BU).times.OPD 4. The method according to claim 3 wherein said method further comprises prior to moving said selected displacer element, selecting the next appropriate displacer element for movement and determining that said selected appropriate displacer element movement would not preclude moving said next appropriate displacer element. 5. The method according to claim 4 wherein K=0.0054. 6. The method according to claim 5 wherein a=1.17 and b=0.00033.
	summary
	claims	1. A computer-implemented method comprising:receiving at least one reactor core parameter distribution associated with a state of a core of a reference nuclear reactor;generating an initial fuel loading distribution for a simulated beginning-of-cycle (BOC) core of a nuclear reactor, the simulated BOC core of the nuclear reactor including a simulated beginning-of-life (BOL) core of the nuclear reactor;selecting an initial set of positions associated within a set of regions within the simulated BOC core of the nuclear reactor, wherein the initial set of positions correspond to the set of regions;generating an initial set of fuel design parameter values utilizing at least one design variable of at least one of the set of regions;calculating at least one reactor core parameter distribution of the simulated BOC core utilizing the initial set of fuel design parameter values associated with the set of regions located at the initial set of positions of the simulated BOC core;generating a loading distribution by performing at least one perturbation process on the set of regions of the simulated BOC core in order to determine a subsequent set of positions for the set of regions within the simulated BOC core; andcausing a fuel handler to arrange one or more fuel assemblies in a core of the nuclear reactor according to the loading distribution. 2. The method of claim 1, wherein the receiving the at least one reactor core parameter distribution associated with the state of the core of the reference nuclear reactor includes:receiving at least one reactor core parameter distribution associated with an equilibrium state of the core of the reference nuclear reactor. 3. The method of claim 1, wherein the reference nuclear reactor includes:at least one of a reference thermal nuclear reactor, a reference fast nuclear reactor, a reference breed-and-burn nuclear reactor, or a reference traveling wave reactor. 4. The method of claim 1, wherein the core of the reference nuclear reactor includes:at least one fuel assembly. 5. The method of claim 4, wherein the at least one fuel assembly of the core of the reference nuclear reactor includes at least one pin. 6. The method of claim 1, wherein the at least one reactor core parameter distribution associated with the state of the core of the reference nuclear reactor includes:at least one of a power density distribution, a rate of change of a power density distribution, a reactivity distribution, or a rate of change of a reactivity distribution associated with the state of the core of the reference nuclear reactor. 7. The method of claim 1, wherein at least a portion of the BOC core includes at least one of recycled nuclear fuel, unburned nuclear fuel, or enriched nuclear fuel. 8. The method of claim 1, wherein the generating an initial fuel loading distribution for a simulated beginning-of-cycle (BOC) core of a nuclear reactor includes:randomly generating the initial fuel loading distribution for the simulated BOC core of the nuclear reactor. 9. The method of claim 1, wherein the simulated BOC core of the nuclear reactor includes a plurality of simulated fuel assemblies. 10. The method of claim 1, wherein the at least one of the set of regions encompasses at least one fuel assembly. 11. The method of claim 1, wherein the at least one of the set of regions is a three-dimensional region having at least one of a selected volume, a selected shape, or a selected number of regions. 12. The method of claim 1, wherein the at least one design variable of the at least one of the set of regions includes a thermodynamic variable of the at least one of the set of regions. 13. The method of claim 1, wherein the generating the initial set of fuel design parameter values utilizing the at least one design variable of the at least one of the set of regions includes:generating the initial set of fuel design parameter values utilizing a neutronic parameter of the at least one of the set of regions. 14. The method of claim 13, wherein the utilizing the neutronic parameter of the at least one of the set of regions includes:generating the initial set of fuel design parameter values utilizing a k-infinity value of the at least one of the set of regions. 15. The method of claim 1, wherein the generating the initial set of fuel design parameter values utilizing the at least one design variable of the at least one of the set of regions includes:generating an initial set of enrichment values utilizing the at least one design variable of the at least one of the set of regions. 16. The method of claim 1, wherein the generating the initial set of fuel design parameter values utilizing the at least one design variable of the at least one of the set of regions includes:generating an initial set of pin dimension values associated with a set of pins of a fuel assembly of the simulated BOC core of the nuclear reactor utilizing the at least one design variable of the at least one of the set of regions. 17. The method of claim 16, wherein the generating the initial set of pin dimension values associated with the set of pins of the fuel assembly of the simulated BOC core of the nuclear reactor utilizing the at least one design variable of the at least one of the set of regions includes:generating at least one of an initial set of pin configuration values, an initial set of pin geometry values, or an initial set of pin composition values associated with the set of pins of the fuel assembly of the simulated BOC core of the nuclear reactor utilizing the at least one design variable of the at least one of the set of regions. 18. The method of claim 1, wherein the at least one design variable of the at least one of the set of regions includes:at least one design variable of each of a set of pins of the set of regions, wherein each of the initial set of fuel design parameter values is associated with one of the set of regions of the simulated BOC core of the nuclear reactor. 19. The method of claim 18, wherein each of the initial set of fuel design parameter values is associated with one of the pins of the at least one of the set of regions of the simulated BOC core of the nuclear reactor. 20. The method of claim 1, wherein the calculating the at least one reactor core parameter distribution of the simulated BOC core utilizing the initial set of fuel design parameter values associated with the set of regions located at the initial set of positions of the simulated BOC core includes:calculating at least one of a power density distribution, a rate of change of a power density distribution, a reactivity distribution, or a rate of change of a reactivity distribution of the simulated BOC core utilizing the initial set of fuel design parameter values associated with the set of regions located at the initial set of positions of the simulated BOC core. 21. The method of claim 1, wherein the subsequent set of positions define the loading distribution for the simulated BOC core. 22. The method of claim 1, wherein the subsequent set of positions reduce a deviation metric between the at least one reactor core distribution of the simulated BOC core and the received at least one reactor core parameter distribution associated with the state of the core of the reference nuclear reactor below a selected tolerance level. 23. The method of claim 1, further comprising:reporting the subsequent set of positions of the set of regions of the simulated BOC core. 24. A non-transitory computer-readable medium comprising program instructions, wherein the program instructions are executable to:receive at least one reactor core parameter distribution associated with a state of a core of a reference nuclear reactor;generate an initial fuel loading distribution for a simulated beginning-of-cycle (BOC) core of a nuclear reactor, the simulated BOC core of a nuclear reactor including a simulated beginning-of-life (BOL) core of the nuclear reactor;select an initial set of positions associated with a set of regions within the simulated BOC core of the nuclear reactor, wherein the initial set of positions correspond to the set of regions;generate an initial set of fuel design parameter values utilizing at least one design variable of at least one of the set of regions;calculate at least one reactor core parameter distribution of the simulated BOC core utilizing the initial set of fuel design parameter values associated with the set of regions located at the initial set of positions of the simulated BOC core;generate a subsequent loading distribution by performing at least one perturbation process on the set of regions of the simulated BOC core in order to determine a subsequent set of positions for the set of regions within the simulated BOC core; andcause a fuel handler to arrange one or more fuel assemblies in a core of the nuclear reactor according to the subsequent loading distribution. 25. A system comprising:a controller including one or more processors operable to execute program instructions maintained on a non-transitory computer-readable medium, the program instructions configured to:receive at least one reactor core parameter distribution associated with a state of a core of a reference nuclear reactor;generate an initial fuel loading distribution for a simulated beginning-of-cycle (BOC) core of a nuclear reactor;select an initial set of positions associated with a set of regions within the simulated BOC core of the nuclear reactor, each of the initial set of positions corresponding to one of the set of regions;generate an initial set of fuel design parameter values utilizing at least one design variable of at least one of the set of regions, wherein each of the initial set of fuel design parameter values is associated with one of the set of regions of the simulated BOC core of the nuclear reactor;calculate at least one reactor core parameter distribution of the simulated BOC core utilizing the initial set of fuel design parameter values associated with the set of regions located at the initial set of positions of the simulated BOC core;generate a subsequent loading distribution by performing at least one perturbation process on the set of regions of the simulated BOC core in order to determine a subsequent set of positions for the set of regions within the simulated BOC core, the subsequent set of positions defining the loading distribution for the simulated BOC core, wherein the subsequent set of positions reduce the difference between the at least one reactor core parameter distribution of the simulated BOC core and the received at least one reactor core parameter distribution associated with the state of the core of the reference nuclear reactor below a selected tolerance level; andcause a fuel handler to arrange one or more fuel assemblies in a core of the nuclear reactor according to the subsequent loading distribution. 26. The system of claim 25, wherein the at least one reactor core parameter distribution is associated with an equilibrium state of the core of the reference nuclear reactor. 27. The system of claim 25, wherein the reference nuclear reactor comprises at least one of a reference thermal nuclear reactor, a reference fast nuclear reactor, a reference breed-and-burn nuclear reactor, or a reference traveling wave reactor. 28. The system of claim 25, wherein the at least one reactor core parameter distribution associated with the state of the core of the reference nuclear reactor includes:at least one of a power density distribution, a rate of change of the power density distribution, a reactivity distribution, or a rate of change of the reactivity distribution associated with the state of the core of the reference nuclear reactor. 29. The system of claim 25, wherein the reference nuclear reactor includes at least one fuel assembly. 30. The system of claim 25, wherein the reference nuclear reactor comprises at least one fuel assembly including at least one fuel pin. 31. The system of claim 25, wherein at least a portion of the simulated BOC core includes at least one of recycled nuclear fuel, unburned nuclear fuel, or enriched nuclear fuel. 32. The system of claim 25, wherein the simulated BOC core includes a plurality of simulated fuel assemblies. 33. The system of claim 25, wherein the generating the initial set of fuel design parameter values utilizing the at least one design variable of the at least one of the set of regions includes:utilizing a thermodynamic variable of the at least one of the set of regions. 34. The system of claim 25, wherein the generating the initial set of fuel design parameter values utilizing the at least one design variable of the at least one of the set of regions includes utilizing a neutronic parameter of the at least one of the set of regions. 35. The system of claim 34, wherein the utilizing the neutronic parameter of the at least one of the set of regions includes utilizing a k-infinity value of the at least one of the set of regions. 36. The system of claim 25, wherein the generating the initial set of fuel design parameter values utilizing the at least one design variable of the at least one of the set of regions includes:generating an initial set of enrichment values utilizing the at least one design variable of the at least one of the set of regions. 37. The system of claim 25, wherein the generating the initial set of fuel design parameter values utilizing the at least one design variable of the at least one of the set of regions includes:generating an initial set of pin dimension values associated with a set of pins of a fuel assembly of the simulated BOC core of the nuclear reactor utilizing at least one design variable of the at least one of the set of regions. 38. The system of claim 25, wherein each of the initial set of fuel design parameter values is associated with one of the set of regions of the simulated BOC core of the nuclear reactor. 39. The system of claim 38, wherein the generating the initial set of fuel design parameter values utilizing the at least one design variable of the at least one of the set of regions includes:utilizing at least one design variable of each of a set of pins of the set of regions, wherein each of the initial set of fuel design parameter values is associated with one of the pins of the one of the set of regions of the simulated BOC core of the nuclear reactor. 40. The system of claim 25, wherein the calculating the at least one reactor core parameter distribution of the simulated BOC core utilizing the initial set of fuel design parameter values associated with the set of regions located at the initial set of positions of the simulated BOC core includes:calculating at least one of a power density distribution, a rate of change of the power density distribution, a reactivity distribution, or a rate of change of the reactivity distribution of the simulated BOC core utilizing the initial set of fuel design parameter values associated with the set of regions located at the initial set of positions of the simulated BOC core. 41. The method of claim 1, wherein causing the fuel handler to arrange the one or more fuel assemblies in the core of the nuclear reactor according to the loading distribution comprises causing the fuel handler to grip a selected fuel assembly and move the selected fuel assembly from a first location to a second location. 42. The non-transitory computer-readable medium of claim 24, wherein the program instructions are executable to cause the fuel handler to arrange the one or more fuel assemblies in the core of the nuclear reactor according to the subsequent loading distribution by causing the fuel handler to grip a selected fuel assembly and move the selected fuel assembly from a first location to a second location. 43. The system of claim 25, wherein the program instructions are configured to cause the fuel handler to arrange the one or more fuel assemblies in the core of the nuclear reactor according to the subsequent loading distribution by causing the fuel handler to grip a selected fuel assembly and move the selected fuel assembly from a first location to a second location.
046506322	description	DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention will be described with reference to a particular magnetic confinement plasma device, the Poloidal Diverter experiment (PDX), located at Princeton University, Plasma Physics Laboratory. As will be appreciated by those skilled in the art, the present invention can be readily adapted to other applications. The Poloidal Diverter experiment is being used to study impurity control and another significant processes in high-temperature neutral beam heated plasmas. With reference to the schematic plan view of FIG. 1, the PDX machine 10, a tokamak, has a toroidal vacuum vessel 12 for containing a magnetically-confined plasma. The plasma is heated by four neutral beam injectors, 21-24, as explained in the following references: W. L. Gartner et al, "Proceeding of the 8th Symposium on Engineering Problems of Fusion Research", San Francisco, Calif. 1979, (IEEE, N.Y, N.Y.) p. 972; M. M. Menon et al., also appearing in the "Proceeding of the 8th Symposium on Engineering Problems of Fusion Research", p. 656; and H. W. Kugel and M. Ulrickson "The Design of the PDX Tokamak Wall Armor and Inner Limiter System", American Nuclear Society, Nuclear Technology/Fusion, Vol. 2, October, 1982, pp. 712-722. The four beam lines inject a total heating power of 6 MW H.sup.0 or 8 MW D.sup.0. The injection is at a nearly perpendicular injection angle (9.degree.). The measured neutral beam power density profile in the focal plane is almost axially symmetric and approximately Gaussian from the maximum power point to about 10% of maximum with a characteristic half-angle-at-1/e of 1.1.degree. to 1.8.degree.. The expected maximum power density on beam axis at the inner wall of the torus for a 300 millisecond injection is 3.2 kW/cm.sup.2. Eventual 500 millisecond injection pulse lengths are anticipated. Incident power densities of this magnitude, for pulse durations up to 500 milliseconds, require the protection of the 0.95 cm thick 304 stainless steel inner wall of PDX. The adopted armor plate consists of arrays 30 of water cooled, titanium carbide coated graphite tiles 32, supported on inner wall 34 of the torus, opposite each beam port. Channels 36 formed in tiles 32 provide paths for coolant flow. Titanium plates 38 shield the gaps between the graphite units. The PDX wall armor is designed to function as an inner wall thermal armor, a neutral beam power diagnostic, and a large area inner plasma limiter. The maximum PDX neutral beam power densities are capable of melting the surface of the 0.95 cm thick stainless steel-304 inner wall in about 250 milliseconds if injection occurs in the absence of a plasma, i.e., during conditions allowing essentially 100% power transmission to the inner wall. During normal operation with typical PDX plasma densities, beam transmission is approximately 10-30%, thus proportionally reducing the power density through the inner wall. However, if a disruption in the plasma current occurs during neutral beam injection, the transmitted power could increase to its maximum value. In principle, beam injection is terminated by a sense circuit approximately 10 milliseconds after the disappearance of the plasma current. However, the PDX armor is designed to accommodate this range of conditions and increase the margin of safety while adequately shielding the inner wall of the torus from full power for 0.5 seconds in the absence of the plasma. Several systems are provided to study neutral beam heating in PDX, including the direct measurement of injected power or power density for a variety of beam and plasma conditions. These systems generally comprise an array of 64 thermocouples installed in the graphite tiles, and calibrated calorimeters installed in the water cooling lines 36 which cool the graphite tiles. Window ports on the outer wall 40 of the torus permit the use of IR cameras to monitor the front face temperature of the armor at regions of maximum power deposition. Such measurements provide a safety diagnostic for monitoring the integrity of the armor and also yield useful information on armor front face temperature profiles and effective heat transfer coefficients. The PDX inner wall armor (i.e. array 30) is designed to also function as a plasma limiter. It has been estimated that a conventional poloidal rail inner limiter has a peak plasma thermal load of the order of 2 kW/cm.sup.2 at mid-plane, whereas in an axisymmetric toroidal limiter, the peak plasma thermal load at mid-plane would be about 200 W/cm.sup.2 (J. A. Schmidt, "Comments on Plasma Physics and Controlled Fusion" Vol. 5 (1980) p. 225. This substantially lower thermal load for a toroidal limiter is expected to provide a reduction in impurity emissions, and thermal fatigue. The PDX toroidal limiter configuration will contribute useful information concerning plasma and disruption thermal loads for a nearly axisymmetric limiter, impurity emissions, surface damage, mechanical stability, and overall reliability. Access to the PDX vessel is obtained via 31 cm by 34 cm ports. This places a maximum size constraint on all armor components and installation procedures. The PDX plasma has a minor diverted radius of 47 cm and a major diverted radius of 145 cm. Undiverted dimensions are 57 cm and 145 cm, respectively. The toroidal radius of curvature of the PDX inner wall is 71.4 cm. This relatively small radius of curvature requires armor segments of a comparable curvature or, equivalently, many narrow flat plates. However, practical constraints required the selection of a flat plane geometry of 9.93 cm front face width for the PDX armor design as a compromise between maximizing flat plate width in order to reduce the required total number of plates, and minimizing the amount of plate-edge exposure and protrusion beyond the mean armor radius as the plate width is increased. An armor length of 61 cm (or 30.5 cm above and below the mid-plane), was chosen to prevent protrusion beyond the shielding provided by the upper and lower inner limiters. The design tile length produced an approximately square tile shape, with an odd number of tiles per backing plate. An approximately square shape achieves a more symmetric thermal expansion, while an odd number of tiles was chosen to eliminate any gap at the mid plane where the neutral beam power is greatest. Each of the four armor units consists of three subunits containing either two or three backing plates, which provide mounting to inner wall 34. The graphite armor units cover approximately 70% of the circumference of the inner wall, and each graphite armor unit is positioned to intercept injected neutral beams. The 30% of the inner wall circumference that does not receive direct neutral beam power is armored with titanium plate which acts as an inner wall plasma calorimeter for measuring thermal loading during normal operations and disruptions in the plasma current. The armor is grounded to the PDX vessel which is electrically isolated during plasma shots. The following is a description of vertical temperature toroidal limiter, during both ohmic and neutral beam heated discharges. With reference to FIG. 3, the vertical temperature profiles along the graphite tile array 30 were taken with a scanning infrared camera 50 which views array 30 through a conventional high transmission Zinc Selenide infrared window 52 formed in outer wall 40 of device 10. Camera 50 is an Inframetrics Model 210 scanning infrared camera, which was positioned to view the limiter of array 30 from a distance of about 2 meters. The camera operates in two wavelengths ranges: 3 to 5 micrometers, and 8 to 12 micrometers. The camera was used in a line scan mode where temperatures along a single line are recorded. Since the camera used is designed for horizontal scanning operation only, a conventional 90.degree. image rotator 54 (such as Inframetrics Model No. AC048) was employed upstream of the camera to facilitate vertical scanning of array 30. It will become immediately apparent to those skilled in the art, that an array of infrared photodiodes can be substituted for the infrared camera, if less stringent spatial resolution requirements are acceptable. The time response of the system was about 125 microseconds, and a scan was taken every three milliseconds. The scans were archived using a computer data acquisition system. The camera and signal processing electronics were calibrated using standard black body sources. The emissivity of the limiter surface was detemined by uniformly heating the limiter by circulating warm water (approximately 50.degree. C.) through the limiter cooling lines, and comparing the infrared signal to the limiter thermocouples. It was found that the emissivity was different for the two wavelength bands. The emissivity for the 3 to 5 micrometer band was 0.95 to 0.98 across the face of the limiter, while emissivity in the 8 to 12 micrometer band varied between 0.4 and 0.7. In view of the greater signal-to-background ratio obtained with the 3 to 5 micrometer band, and the relatively constant emissivity at these wavelengths, the results presented here were obtained using the 3 to 5 micrometer band. After the correction for emissivity, the temperatures determined from the two wavelength bands agreed to within plus or minus 10.degree. C. The measurements were performed during a period of extensive high beta plasma studies as described in "High-Beta Experiments with Neutral Beam Injection on PDX", D. Johnson et al, "Plasma Physics and Controlled Nuclear Fusion Research 1982" (Proceedings of the 9th International Conference, Baltimore, 1982) IAEA, Vienna, Vol. 1, No. 9 (1982). The temperature profiles measured on the inner toroidal limiter were obtained using both co-and-counter injection geometry. The discharges were typically initiated at the major radius and then brought into contact with the inner limiter. The inner toroidal limited plasmas had a major radius of 125 cm and a minor radius of 40 cm. FIG. 4 shows a typical vertical temperature profile following a beam heated discharge. A shift of the thermal pattern below the mid plane (see d=0 in FIG. 4, and line 60 in FIG. 2) is unexplained at this time. The asymmetry of the two peaks 62, 64 is tentatively presumed to be due to the directed momentum of the fast beam particles. The asymmetry is seen most strongly following neutral beam, as opposed to ohmic heating shots. The ratio of the thermal load in the two peaks is about 0.3. The temperatures are consistent with about 40% of the input power during the beam pulse going to the limiter. The decay rate for the temperature profiles following beam heated discharges is shown in FIG. 5. The dotted line is the result of a theoretical calculation of the limiter front face temperature using temperature dependent material parameters and a peak thermal load of 0.25 kW/cm.sup.2 for 200 milliseconds. The thermal load was reduced from the temperature rise during the beam portion of the discharge. The time dependence of the power load during the beam could not be determined because of noise problems caused by the beam. The noise was due to electrical pickup and possibly beam heating of small bits of dust on the limiter surface resulting in small hot spots. It was observed that the predominant thermal load occurs during the beam portion of the discharge. This is consistent with the very small temperature rises observed during non-disruptive portions of ohmic heated discharges. An array of 64 thermocouples mounted in the graphite tiles 32 was used to monitor the toroidal asymmetry of the thermal depositions. Data taken from the array show that the power deposition was toroidally symmetric except in those areas where there were inner wall diagnostic apertures. In these locations, power is deposited on the edge of the aperture and/or behind the limiter, resulting in slightly higher power deposition. Measurements of ohmic heated discharges followed the beam-heated discharges described above. Typical plasma parameters include: toroidal magnetic field of approximately 12 kilogauss, I.sub.p between the 220 and 270 kilo-amperes, line average electron density 2.5 10.sup.-13 cm.sup.-3, and a magnetic safety factor (q) of 3.5. FIG. 6 shows a typical temperature profile sequence preceding and following a major disruption 70 of an ohmic heated discharge. It was observed that a single heat precursor profile 72 appeared about 50 milliseconds prior to a major disruption 70, within an initial rate of rise of 2.4.degree. C. per millisecond. The temperature of profile prior to the disruption could not be determined because the heat flux from the ohmically heated discharge was too small to cause measurable temperature differences across the graphite limiter. A series of inner wall temperature profile measurements were made over several hours of operation using sensitive thermocouples mounted on a titanium plate on the north-side of the limiter wall. Examination of these measurements revealed a double peak that occurred during normal ohmic heated discharges [a phenomenon reported by R. J. Fonck, et al, "Impurity Levels and Power Loading in the PDX Tokamak with High Power Neutral Beam Injection", "Plasma Surface Interactions in Controlled Fusion Devices, 1982", (Proceedings of the 5th International Conference, Gatlinburg, Tenn., June 1982), J. Nucl. Mater., 111 & 112, 343 (1982)]. Note also that the sequence of temperature profiles 74 following the disruption are double peaked and initially symmetrical. FIG. 7 shows a typical temperature profile following a disruption in an ohmically heated discharge. The deposition is still shifted down by about the same amount as was found for the neutral beam heated discharges (see FIG. 4). Theoretical calculations of front-face tile temperature using temperature dependent material parameters and a thermal load of 5-10 kW/cm.sup.2 for the 3-6 millisecond duration are consistent with observed temperatures. This load time is consistent with the measured plasma current decay rate of approximately 42 kiloamperes per millisecond. The temperature histories prior to the disruption indicate a thermal load of less than 20 W/cm.sup.2. The Schmidt model for scrape-off of a toroidal limiter [J. A. Schmidt, "Tokamak Impurity-Control Techniques", "Comments on Plasma Physics and Controlled Fusion", Vol. 5, 225 (1980)] predicts a double peaked temperature profile. Using this model, the scrape-off length (.lambda.) was derived as a function of the separation of the temperature peaks for the case of a flat, vertical, inner toroidal limiter. The results are shown in FIG. 8, a plot of one-half theoretical peak separation versus .lambda.. The inferred scrape-off lengths are=1.0 cm for the neutral beam discharges and .lambda.=0.5 cm for the postdisruption ohmic heated discharges. These values are consistent with other measurements made on PDX, as reported in "Interactions in Controlled Fusion Devices 1982" (Proc. 5th Intl. Conf. Gatlinburg, Tenn., June, 1982), J. Nucl. Mater., 111 & 112, 130 (1982). The observed symmetry in the toroidal direction is predicted by the model. A peak power load of 250 w/cm.sup.2, deduced from the temperature profile, agrees with the peak power predicted by the model for 40% of the input power going to the limiter. The filling in of the valley between the peaks indicates the presence of a radial transport which is not included in the model in an explicit manner. While radial transport is implicitly included in the scrape-off thickness in the model, the power is assumed to flow only along field lines. This results in the power flux being predicted to be zero at the limiter plasma tangency point (midplane in the PDX case). The same radial transport which results in the scrape-off length will carry power to the tangency point, [according to S. A. Cohen, R. Budny, G. M. McCracken, M. Ulrickson, "Mechanisms Responsible for Topographical Changes in PLT Stainless-Steel and Graphite Limiters," J. Nucl. Fus. 21, 233 (1981)] and fill in the profile, as was observed. The lack of a double peak before disruption implies that the radial transport is greatly enhanced just prior to disruption. While it is true that enhanced radial transport will result in longer scrape-off lengths giving a wider peak separation, it will also result in more filling in of the space beween the peaks. Also, the longer scrape-off lengths result in lower peak power densities. Under such conditions, the radial transport to the tangency point can dominate the power flow. This could be particularly true if field lines are becoming stochastic prior to a disruption. Those skilled in the art could implement various methods for automatically detecting the precursor peaks. For example, a simple method involves focusing several individual infrared photodiode detectors to view points on the surface of the inner limiter laying along a vertical line. A rapid increase in the signal strength from detectors viewing the midplane of the limiter relative to the signal strength of detectors viewing the outer edge of the limiter would indicate the presence of the disruption precursor. Either the relative rates of change in the respective signal strengths, the relative absolute differences in signal strength, or ratios of the signal strength between the respective detectors could be monitored for the disruption precursors. Indicators such as these could be introduced into a control feedback loop or used to trigger an electronic threshold to cause corrective control action to be taken. A more elaborate method, for example, involves using fast automatic data processing equipment to analyze the temperature profile detected with an array of individual detectors or a scanning camera system. The fast automatic data processing system could be programmed to recognize the characteristic disruption precursor pattern and adjust the tokamak operating parameters in a suitable manner to avoid the disruption or to reduce its severity. Thus it can be seen that in those major plasma disruptions characterized by a temperature profile precursor, a fast infrared camera arranged according to the present invention can detect the precursor in time to provide a realtime interval before disruption, which allows ameliorating, or even fully corrective action to be taken. In the above example, the time interval prior to disruption was 50 msec. An example of corrective action that can be taken within this time is cited in "The Effect of Current Profile Evolution on Plasma-Limiter Interaction and the Energy Confinement Time", R. J. Hawryluk, et al., Nucl. Fusion Vol. 19 (1979) p. 1307, which describes an automatic control of operating parameters so as to optimize reactor performance and avoid the aforementioned deleterious effects of a plasma disruption. It is anticipated that other, more fully corrective measures, will be devised so as to sustain continuous operation despite potential plasma disruptions. The arrangement of the present invention can be employed to initiate such corrective action. Another use of this invention is to detect the presence of so-called stationary mode plasma instabilities, i.e. plasma instabilities characterized by non-fluctuating, non-rotating, stationary magnetic structures in the plasma which are undetectable using the conventional magnetic sensing coils used to detect rapid fluctuations in magnetic structure.
	claims	1. A method comprising:propagating a nuclear fission traveling wave burnfront along first and second dimensions within a plurality of nuclear fission fuel subassemblies in a reactor core of a nuclear fission traveling wave reactor;determining an existing shape of the nuclear fission traveling wave burnfront;determining a desired shape of the nuclear fission traveling wave burnfront, andin response to the determined desired shape, controllably migrating selected ones of the plurality of nuclear fission fuel subassemblies along the first dimension from respective first locations in the reactor core to respective second locations in the reactor core to alter the existing shape to resemble the desired shape, wherein the respective first locations and the respective second locations are on opposite sides of the nuclear fission traveling wave burnfront. 2. The method of claim 1, wherein the first dimension is substantially orthogonal to an elongated axis of the plurality of nuclear fission subassemblies. 3. The method of claim 1, wherein:the first dimension includes a radial dimension; andthe desired shape defines the nuclear fission traveling wave burnfront in an axial dimension. 4. The method of claim 1, wherein:the first dimension includes an axial dimension; andthe desired shape defines the nuclear fission traveling wave burnfront in a radial dimension. 5. The method of claim 1, wherein:the first dimension includes a lateral dimension; andthe desired shape defines the nuclear fission traveling wave burnfront in an axial dimension. 6. The method of claim 1, wherein:the first locations include outward locations; andthe second locations include inward locations. 7. The method of claim 1, wherein:the first locations include inward locations; andthe second locations include outward locations. 8. The method of claim 1, wherein controllably migrating selected ones of the plurality of nuclear fission fuel subassemblies along the first dimension from respective first locations to respective second locations includes rotating at least one of the selected ones of the plurality of nuclear fission fuel subassemblies. 9. The method of claim 1, wherein controllably migrating selected ones of the plurality of nuclear fission fuel subassemblies along the first dimension from respective first locations to respective second locations includes inverting at least one of the selected ones of the plurality of nuclear fission fuel subassemblies. 10. The method of claim 1, wherein the desired shape is based on a selected set of dimensional constraints including a predetermined maximum distance along the second dimension. 11. The method of claim 1, wherein the desired shape is based on a selected set of dimensional constraints and the selected set of dimensional constraints is a function of at least one burnfront criteria. 12. The method of claim 11, wherein the burnfront criteria includes neutron flux. 13. The method of claim 12, wherein the neutron flux is associated with at least one of the selected ones of the plurality of nuclear fission fuel subassemblies. 14. The method of claim 11, wherein the burnfront criteria includes neutron fluence. 15. The method of claim 14, wherein the neutron fluence is associated with at least one of the selected ones of the plurality of nuclear fission fuel subassemblies. 16. The method of claim 11, wherein the burnfront criteria includes burnup. 17. The method of claim 16, wherein the burnup is associated with at least one of the selected ones of the plurality of nuclear fission fuel subassemblies. 18. The method of claim 11, wherein the burnfront criteria includes burnfront location within at least one of the selected ones of the plurality of nuclear fission fuel subassemblies. 19. The method of claim 1, wherein controllably migrating selected ones of the plurality of nuclear fission fuel subassemblies along the first dimension from respective first locations to respective second locations includes controllably migrating selected ones of the plurality of nuclear fission fuel subassemblies spirally along the first dimension from respective first locations to respective second locations. 20. The method of claim 1, wherein the desired shape of the nuclear fission traveling wave burnfront includes a shape chosen from a substantially spherical shape, a shape conforming to a selected continuously curved surface, a shape that is substantially rotationally symmetrical around the second dimension, and a shape having substantial n-fold rotational symmetry around the second dimension. 21. The method of claim 1, wherein the shape of the nuclear fission traveling wave burnfront along the second dimension is asymmetrical. 22. The method of claim 21, wherein the shape of the nuclear fission traveling wave burnfront is rotationally asymmetrical around the second dimension. 23. The method of claim 1, further comprising initiating a nuclear fission traveling wave burnfront with a plurality of nuclear fission traveling wave igniter assemblies. 24. The method of claim 23, further comprising removing at least one of the plurality of nuclear fission traveling wave igniter assemblies prior to controllably migrating selected ones of the plurality of nuclear fission fuel subassemblies along the first dimension from respective first locations to respective second locations. 25. The method of claim 24, wherein removing at least one of the plurality of nuclear fission traveling wave igniter assemblies prior to controllably migrating selected ones of the plurality of nuclear fission fuel subassemblies along the first dimension from respective first locations to respective second locations includes removing at least one of the plurality of nuclear fission traveling wave igniter assemblies from the second locations prior to controllably migrating selected ones of the plurality of nuclear fission fuel subassemblies along the first dimension from respective first locations to respective second locations. 26. The method of claim 1, wherein the desired shape of the nuclear fission traveling wave burnfront includes approximating a Bessel function. 27. The method of claim 1, wherein controllably migrating further includes:controllably migrating a first nuclear fission fuel subassembly of the plurality of nuclear fission fuel subassemblies along the first dimension from a first location of the respective first locations in the reactor core to a second location of the respective second locations in the reactor core, wherein the first nuclear fission fuel subassembly includes fertile fuel to be bred up at the second location and wherein the first location has a lower burn-up rate than the second location. 28. The method of claim 1, wherein controllably migrating further includes:controllably migrating a first nuclear fission fuel subassembly of the plurality of nuclear fission fuel subassemblies along the first dimension from a first location of the respective first locations in the reactor core to a second location of the respective second locations in the reactor core, wherein the first nuclear fission fuel includes spent fuel at the second location and wherein the first location has a higher burn-up rate than the second location. 29. The method of claim 1, wherein controllably migrating further includes migrating each individual one of the plurality of nuclear fission fuel subassemblies based on relative burn-up rates at a first location of the respective first locations on a first side of the nuclear fission traveling wave burnfront and a second location of the respective second locations on opposite sides of the nuclear fission traveling wave burnfront.
	abstract	The object of this invention is to provide a fiber-reinforced concrete cask that ensures easy working, enables reducing working cost, excels in strength, durability and heat resistance and enables minimizing cracking; a process for fabrication of the same; and a supporting frame for molding the concrete cask. In particular, concrete cask (10) formed through injecting and solidification of concrete (11) is characterized in that sheets of reinforcement fibers having a thermal expansion coefficient equal to or lower than that of concrete (11) are provided on at least the outer circumferential surface and the inner circumferential surface of the concrete cask (10) and that the inner circumferential surface of outer sheet (21) and the outer circumferential surface of inner sheet (22) are connected with each other by strings of reinforcement fibers (23). Preferably, carbon fibers are used as the reinforcement fibers.
052934179	claims	1. A method of fabricating a collimator for use in a radiation imager device having a point radiation source, comprising: selectively removing material from each of a plurality of collimator plates to form passages therein corresponding to a respective selected pattern, each of said selected patterns corresponding to the arrangement of an array of radiation detector elements adjoining said collimator in the assembled imager device; and stacking said collimator plates together to form a collimator body, said collimator plates being positioned so that passages in each of said collimator plates are disposed in spaced relation to respective passages in adjoining collimator plates to form channels through said collimator body, the longitudinal axis of each of said channels having a respective selected orientation angle; each of said collimator plates comprising substantially only a radiation absorbent material selected to absorb radiation of the wavelength distribution emitted by said radiation point source and the number of collimator plates being selected to provide a predetermined overall thickness of radiation absorptive material so as to absorb substantially all radiation striking the collimator from said radiation point source; the step of selectively removing material further comprising the steps of forming a respective mask corresponding to each of said plates, said mask each having a respective pattern of openings therein corresponding to a pattern of radiation detector elements in the radiation detector array to which said collimator is to be mated, and then etching each said collimator plates through its respective mask to form said passages therein. 2. The method of claim 1 wherein said radiation absorbent material comprises one of the group consisting of tungsten, gold, and lead. 3. The method of claim 1 wherein the step of selectively removing material from said collimator plates comprises wet etching tungsten sheets through a mask having said selected pattern. 4. The method of claim 3 wherein said step of etching further comprises removing portions of said mask remaining on said collimator plate after etching said passages. 5. The method of claim 1 wherein said step of stacking said collimator plates further comprises aligning said plates so that the sidewalls of said passages are positioned with respect to adjoining sidewalls of respective passages in adjoining ones of said collimator plates to form channels in said collimator body having longitudinal axes aligned with said respective selected orientation angles.
	claims	1. A tool for making two substantially simultaneous cuts along an elongated length of a spline of a boiling water reactor cruciform shaped control rod having four elongated panels radially extending at spaced locations around a circumference of the spline, with each of the panels having two oppositely facing sides and the spline having a central axis extending along the elongated length, the tool comprising:a tool base plate oriented in a substantially horizontal position, substantially perpendicular to the central axis when the control rod is in position to be cut, and the tool base plate is configured to be moved vertically;a first pair of spaced pulley wheels rotatably supported from one side of the tool base plate with one of the first pair of spaced pulley wheels comprising a drive wheel that is operatively connected to a motor to rotate the drive wheel when the motor is in an on state and a second of the first pair of spaced pulley wheels oriented along a first axis extending between the drive wheel and the second of the first pair of spaced pulley wheels;a first band saw blade having a first set of teeth facing in a downward direction, extending around the drive wheel and the second of the first pair of spaced pulley wheels wherein a first side of the first band saw blade extends between the drive wheel and the second of the first pair of spaced pulley wheels and around the second of the first pair of spaced pulley wheels and a second side of the first band saw blade extends between the second of the first pair of spaced pulley wheels and the drive wheel and around the drive wheel wherein the first side of the first band saw blade extends over a first opening in the tool base plate that is sized for the boiling water reactor control rod to axially pass through in a direction of the central axis and the first band saw travels in a first plane, around the drive wheel and the second of the first pair of spaced pulley wheels, substantially parallel to the one side of the tool base plate when the motor is in the on state;a second pair of spaced pulley wheels rotatably supported from the one side of the tool base plate with one of the second pair of spaced pulley wheels comprising a follower wheel that is operatively connected to the drive wheel to rotate the follower wheel when the motor is in an on state and a second of the second pair of spaced pulley wheels oriented along a second axis extending between the follower wheel and the second of the second pair of spaced pulley wheels, the second axis being oriented at a fixed angle greater or less than zero relative to the first axis; anda second band saw blade having a second set of teeth facing in the downward direction, extending around the follower wheel and the second of the second pair of spaced pulley wheels wherein a first side of the second band saw blade extends between the follower wheel and the second of the second pair of spaced pulley wheels and around the second of the second pair of spaced pulley wheels and a second side of the second band saw blade extends between the second of the second pair of spaced pulley wheels and around the follower wheel wherein the first side of the second band saw blade extends over the first opening in the tool base plate that is sized for the boiling water reactor control rod to pass through and the second band saw travels in a second plane, around the follower wheel and the second of the second pair of spaced pulley wheels, substantially parallel to the first plane, when the motor is in the on state. 2. The tool of claim 1 wherein the follower wheel is connected to the drive wheel with a chain and sprocket coupling. 3. The tool of claim 1 wherein the drive wheel and the follower wheel respectively drive the first and second band saw blades at approximately the same speed. 4. The tool of claim 1 wherein the first side of the first band saw blade and the first side of the second band saw blade cross one another over the central axis when the boiling water reactor control rod is positioned in the first opening in the tool base plate. 5. The tool of claim 1 wherein the opening in the tool base plate includes guide supports extending from the tool base plate to contact, ride along and guide each side of the panels through the first opening in the tool base plate when the boiling water reactor control rod panels extend through the opening. 6. The tool of claim 5 wherein the guide supports on either side of each panel are supported about the first opening at a different elevation relative to the central axis. 7. The tool of claim 6 wherein the different elevations are approximately 50 mm apart. 8. The tool of claim 6 wherein the guide supports extend above and below the tool base plate. 9. The tool of claim 1 wherein the tool base plate includes a second opening through which a guide pole can extend to guide movement of the tool base plate in a direction parallel to the central axis when the boiling water reactor control rod panels extend through the first opening. 10. The tool of claim 9 including means for moving the tool base plate along a direction parallel to the central axis. 11. The tool of claim 10 wherein the means for moving the tool base plate is an overhead hoist. 12. The tool of claim 9 including the guide pole and means for supporting the guide pole on a bottom of a spent fuel pool. 13. The tool of claim 9 wherein the guide pole is a guide rail configured to be supported from a reactor building floor with the guide rail extending down into a spent fuel pool. 14. The tool of claim 13 wherein the guide rail is configured to extends down into the spent fuel pool at least six meters. 15. The tool of claim 1 wherein the first and second band saw blades operate to substantially simultaneously cut the boiling water reactor control rod vertically along the spline dividing the boiling water reactor control rod spline into four substantially equal sections. 16. The tool of claim 1 wherein when in an upper position above the boiling water reactor control rod the tool can be rotated 180 degrees to facilitate maintenance. 17. The tool of claim 1 wherein the motor is a hydraulic motor. 18. The tool of claim 1 including a camera on the tool base plate for managing the cutting process. 19. The tool of claim 18 wherein the camera includes a plurality of cameras. 20. The tool of claim 1 wherein the fixed angle is approximately ninety degrees.
	description	1. Field of the Invention The present invention relates to radiation sources, and particularly to a radiation emitting device for use in a scanning imaging system. 2. Description of Prior Art Almost most of conventional radiation sources used in scanning imaging systems are merely capable of generating fan-beam X-rays or cone-beam X-rays. Accordingly, the scanning imaging systems have to employ a line/array of detectors arranged for receiving/intercepting the fan-beam/cone-beam X-rays. As such, a flying-spot X-ray radiation source is proposed and typically used in a X-ray inspection system for inspecting contents of objects, such as packages and containers used in the shipment of cargo among sea, land and air ports. However, the structure of most conventional flying-spot X-ray radiation source is unduly complex. In addition, the resolution of scanning images obtained by such conventional flying-spot X-ray radiation source is commonly unadjustable and therefore the scanning image is unclear. Accordingly, an object of the present invention is to provide a radiation source device that is capable of overcoming the above-mentioned shortcoming associated with unadjustable resolution. In order to achieve the above-mentioned object, a radiation source device is provided. The radiation source device includes a radiation emitter configured for emitting X-rays, an emitter switch, a rotating mechanism, and an annular shielding enclosure. The radiation emitter may be secured to the emitter switch, a disk-shaped collimator. The collimator has a central axial through-hole portion and a plurality of radial apertures configured for collimating the X-rays emitted from the radiation emitter into pencil beams. The through-hole portion receives the radiation emitter and the emitter switch therein. The rotating mechanism is coupled to the through-hole portion of the collimator for rotating the collimator. The annular shielding enclosure has an opening configured for allowing the pencil beams to exit therethrough. The shielding enclosure encloses the collimator, the radiation emitter and the emitter switch therein. The radiation emitter is jointly axially movable with the emitter switch in the through-hole portion between a first position where the radiation source device is in an off state and, the radiation emitter is misaligned with any one of the radial apertures, and thereby the X-rays emitted from the radiation emitter are blocked from exiting from the opening of the shielding enclosure, and a second position where the radiation source device is in an on state and, the radiation emitter is aligned with one of the radial apertures thereby the X-rays emitted form the radiation emitter are capable of exiting from the opening of the shielding enclosure. Preferably, the radiation emitter is radially engaged with the collimator by means of one of splines and flat keys such that the radiation emitter, the emitter switch and the collimator are capable of collectively rotating relative to the shielding enclosure. However, in the on state of the radiation emitter, the radiation emitter and the emitter switch are generally at rest relative to the shielding enclosure. The radiation source may further includes a frame movable along a predetermined direction, the shielding enclosure being mounted on the frame. The present radiation source may be employed in a flying-spot scanning imaging system, because the radiation emitter emits X-rays while the collimator rotates. Accordingly, the resolution of obtained scanning image may be adjusted by controlling the rotating/swinging speed of the collimator. The above and other features of the invention, including various novel details of construction and combination of parts, will now be more particularly described with reference to the accompanying drawings, in which: Reference will now be made to the drawing to describe the present invention in detail. Referring to FIG. 1, this illustrates a radiation source in accordance with a preferred embodiment of the present invention. The radiation source device includes a radiation emitter 50, an emitter switch 80, a collimator, a rotating mechanism and an annular shielding enclosure. The radiation emitter 50 is an essentially cylindrical body. The radiation emitter 50 is provided for emitting X-rays (see FIG. 2). The radiation emitter 50 generally emits cone-beam X-rays 54. The emitter switch 80 is securely coupled to the radiation emitter 50. The collimator is substantially disk-shaped. The collimator includes a main body 30 and a cover 40 attached to the main body 30. The main body 30 has a central axial through-hole portion and a plurality of radial apertures. The main body 30 further includes a shaft 20 configured to be coupled to the rotating mechanism via a shaft adapter. The radial apertures are configured for collimating the X-rays emitted from the radiation emitter 50 into pencil beams. The radiation emitter 50 is axially movably received in the through-hole portion. The rotating mechanism is coupled to the through-hole portion of the collimator for rotating/swinging the collimator. The annular shielding enclosure has first part 10 having a first opening section 90 and second part having a second opening section 90′. The first opening section 90 and the second opening section 90′ cooperatively define an opening configured for allowing the pencil beams to exit therethrough. The shielding enclosure encloses the collimator therein. The shielding enclosure has a through hole for receiving the through hole portion of the collimator, and a shielding stopper 70 attached to the through hole for shielding purposes. Referring to FIG. 2, this is a schematic view showing the spatially relationship between the radiation emitter 50 and the shielding enclosure. The emitter switch 80 is configured for selectively switching the radiation emitter 50 between an off state and an on state. In other words, the radiation emitter 50 is jointly axially movable with the emitter switch 80 in the through-hole portion of the collimator between a first position (shown in solid lines) where the radiation source device is in an off state and, the radiation emitter 50 is misaligned with any one of the radial apertures of the collimator, and thereby the X-rays emitted from the radiation emitter 50 are blocked from exiting from the opening of the shielding enclosure, and a second position (shown in broken lines) where the radiation source device is in an on state and, the radiation emitter 50 is aligned with one of the radial apertures thereby the X-rays emitted form the radiation emitter 50 are capable of exiting from the opening of the shielding enclosure. Preferably, the radiation emitter 50 is securely coupled to the emitter switch 80, and the radiation emitter 50 is radially engaged with the collimator by means of one of splines and flat keys such that the radiation emitter 50, the emitter switch 80 and the collimator are capable of collectively rotating relative to the shielding enclosure. However, in the on state of the radiation source device, the radiation emitter 50 and the emitter switch 80 are generally at rest relative to the shielding enclosure. The radiation source device may further include a frame movable along a predetermined direction, the shielding enclosure being mounted on the frame. Although the present invention has been described with reference to a specific embodiment, it should be noted that the described embodiment is not necessarily exclusive and that various changes and modifications may be made to the described embodiment without departing from the scope of the invention as defined by the appended claims.
	abstract	Embodiments of the invention relate to electron microscopy. Example embodiments relate to an apparatus including a first electron beam source, a second electron beam source, and a receiving unit. The first electron beam source is configured to provide a first low-voltage electron beam to a surface of a sample. The second electron beam source is configured to provide a second low-voltage electron beam to pass through the sample. The receiving unit is configured to analyze the first low-voltage electron beam, or the second low-voltage electron beam, or both the first and the second electron beam to obtain information about the sample.
	summary
	description	This application claims priority to and the benefit of U.S. Provisional Patent Application Ser. No. 62/460,380, filed Feb. 17, 2017, the disclosures of which are incorporated herein in their entirety by reference. This Application relates to an apparatus in which to establish controlled environmental conditions, and a method of operation and use thereof. On occasion it may be desirable to be able undertake manufacturing processes in a controlled environment. Sometimes such processes are undertaken in a chamber that may be referred to as a “glove box”, namely a chamber having a controlled internal environment but also having gloves that allow a person positioned outside the chamber to work upon an object located inside the chamber. One such activity may involve the deposition of a coating material upon a substrate, as by a welding or welding-like process. In an aspect of the invention there is a glove box. It has an enclosure having a working chamber defined therewithin. The enclosure has a viewing portion. The enclosure has at least one gauntlet extending into the working chamber. There is piping connected to permit a selected atmosphere to be established within the chamber. The enclosure has an access by which to introduce a work-piece into the chamber. The enclosure has an angular adjustment by which to tilt at least one of the gauntlet and the viewing portion. In a feature of that aspect of the invention, the access includes an environmental lock antechamber. In an additional feature the environmental lock antechamber has piping to permit the antechamber to be flushed and charged with gases independently of the chamber. In still another feature, the glove box has at least a first parameter read out display, the read-out display being located outside the chamber. In another feature, a seat is mounted within the chamber in which to accommodate the work-piece. In still another feature, the enclosure is angularly adjustable relative to the seat. In yet another feature, there is at least a first sealed utility penetration through a wall of the enclosure. In a further feature, the glove box has a heat exchanger mounted there within by which to adjust temperature within the chamber. In another feature, the glove box has a tool interface there within, and the tool interface includes a coolant line connection. In another feature of the invention, the apparatus has an independently flushable access antechamber mounted to the enclosure. There is a seat in which to mount a work-piece, and a welding electrode holder in which to mount a consumable electrode. A welding electrode power connection passes through a sealed penetration of the enclosure, in use the welding electrode holder being mounted thereto. There is a second gauntlet in addition to the first gauntlet. A heat exchanger is mounted within the enclosure, and is operable to extract heat therefrom. There are controls, for at least one of (a) power to the welding electrode holder; and (b) cooling of the heat exchanger located within the enclosure. In another aspect of the invention there is a glove box. It has an enclosure having a working chamber defined therewithin. The enclosure has a viewing portion and at least one gauntlet extending into the working chamber. There is an access by which to introduce a work-piece into the chamber, and piping by which to introduce gases into the chamber. There is an environmental control system operable to govern temperature within the chamber. In still another aspect of the invention, there is a glove box. It has an enclosure having a working chamber defined there within, the enclosure having a viewing portion and at least a first gauntlet extending into the working chamber. There is an access by which to introduce a work-piece into the chamber, and a tool for use by an operator to engage the work piece. There is a controller of the tool mounted within the chamber, the controller being adjustable by an operator wearing the first gauntlet. In another aspect of the invention there is any combination of any of the features of any one of embodiments shown or described herein, in combination with the features of any other embodiment, except to the extent those features are mutually exclusive. In another aspect of the invention, there is any apparatus substantially as shown or described herein, in whole or in part. The description that follows, and the embodiments described therein, are provided by way of illustration of an example, or examples, of particular embodiments of the principles of the invention. These examples are provided for the purposes of explanation, and not of limitation, of those principles and of the invention. In the description, like parts are marked throughout the specification and the drawings with the same respective reference numerals. The drawings may be understood to be to scale and in proportion unless otherwise noted. The wording used herein is intended to include both singular and plural where such would be understood, and to include synonyms or analogous terminology to the terminology used, and to include equivalents thereof in English or in any language into which this specification many be translated, without being limited to specific words or phrases. For the purposes of this description, a Cartesian frame of reference may be employed. In such a frame of reference, the long, or largest, dimension of an object may be considered to extend in the direction of the x-axis, being the longitudinal axis and the main axis of rotation. The height of the object is measured in the z-direction, and the lateral distance from the central vertical plane is measured in the y-direction. Unless noted otherwise, the terms “inside” and “outside”, “inwardly” and “outwardly”, refer to location or orientation inside the housing of the apparatus. In this specification, the commonly used engineering terms “proud”, “flush” and “shy” may be used to denote items that, respectively, protrude beyond an adjacent element, are level with an adjacent element, or do not extend as far as an adjacent element, the terms corresponding conceptually to the conditions of “greater than”, “equal to” and “less than”. In the Figures, a controlled environment chamber assembly, such as may be referred to as a glove box, is shown generally as 20. It includes a frame or wall structure, or enclosure 22. The wall structure of enclosure 22 is hollow, there being an enclosed volume or space, or accommodation, or chamber 24 defined there within. Chamber 24 is a working chamber, and to the end of permitting the operator to see what he or she is doing, enclosure 22 has a viewing portion, or window 26. Given that the apparatus is a glove box, enclosure 22 has first and second access penetrations 28, 30, and first and second, or, more particularly, left-hand and right-hand gloves, or gauntlets, 32, 34, mounted respectively thereto, and into which, naturally, an operator may place their hands in the usual manner. Gauntlets 32, 34 extend into work chamber 24. The cuffs 36 of gauntlets 28, 30 are mounted to outwardly extending flanges 36 that surround penetrations 28, 30. When not in use, penetrations 28, 30 are sealed from the inside by removable port covers 38. Since glove box 20 is intended to permit work to be conducted in an environment having a controlled atmosphere, glove box 20 is provided with conduits, or hoses, or ductwork, indicated generically as piping 40 that permits gases to be supplied to or extracted from chamber 24, by which means a selected atmosphere may be established within chamber 24. Given the purpose of glove box 20, and the general undesirability of removing viewing window 26 each time it is desired to change a work piece, glove box 20 has an external access 42 by which to introduce a work piece (or tools, or consumables, such as welding electrodes, and so on) into chamber 24 prior to processing, and by which to extract the work piece after processing. Glove box 20 has a support apparatus, or stand, or suspension, or frame, or mounting, or undercarriage, indicated generally as 44. Enclosure 22 is movably mounted to undercarriage 44. In the embodiment shown, enclosure 22 is hingedly mounted, as at hinge 46, such that it has a rotational degree of freedom of motion relative to undercarriage 44. Accordingly, enclosure 22 has an angular adjustment be which it can be tilted relative to undercarriage 44, thereby tilting the viewing panel, window 26, and tilting the access of gauntlets 32, 34. Inside enclosure 22 there is a workstand 48 upon which the workpiece may sit, or to which the workpiece may be secured, during processing. Glove box 22 is also provided with an environmental control system, indicated generally as 50, which may include a heat exchanger 52, mounted within chamber 24, and through which gases contained within chamber 24 may be encouraged to pass. Environmental control system 50 may further include piping connected to deliver heating or cooling fluid to galleries, or passages, formed in work stand 48. Environmental control system 50 is operable to govern temperature within chamber 24. As it may be inconvenient or clumsy for the operator to remove his or her hands from gauntlets 32, 34 during processing, controls 56 are located inside chamber 24 within the reach of gauntlets 32, 34 so that parameter adjustments can be made while wearing the gauntlets. A duplicate set of controls 58 is also located outside chamber 24, to permit control from either inside or outside chamber 24, as may be convenient. The features identified above may be considered in greater detail, commencing with undercarriage 44, followed by enclosure 22, access 42, workstand 48, environmental control system 50, and the controls, be they inside, as at 56, or outside, as at 58. Undercarriage 44 may have the general nature of a stand or frame upon which to mount enclosure 22. In the example shown, undercarriage 44 is an all welded steel structure. It may include a set of vertical, or predominantly vertically extending posts or columns or uprights, 60. Upright 60 could be a single vertical pillar or stand. In the embodiment shown there are four uprights 60 arranged as corners of a rectangle. Undercarriage 44 also includes lateral bracing, or braces, or cross-members 62 between the various pairs of uprights 60. There is an upper set of cross-members 64 defining a rectangular frame at the upper end of undercarriage 44, and a lower set of cross-members 66 at a mid-level height part way along uprights 60. The lower cross-members need not run along the front side, such that undercarriage 44 may be open underneath, like a desk. Undercarriage 44 may also include a frame, stanchion, cradle, arm, or accommodation 68 at which to secure gas reservoirs 70, 72, such as may contain, and be used to supply, inert gases such as argon, or non-participating gases such as CO2. Further, undercarriage 44 may include feet 74. In the embodiment shown, each foot 74 is axially adjustable relative to its associated upright 60, such that the height of apparatus 20 may be adjusted. In that regard, in the embodiment shown each foot has a shank nested within its upright 60 in a telescoping relationship. Glove box 20 may be movable, such that it may be transported to a location where, for example, a repair service is required. To that end, an adjacent pair of, or all of, feet 74 may have a wheel, 76, which may be a caster wheel. Enclosure 22 may have the form of a generally rectangular sided open-topped box 78, having a bottom or base wall 80, a front wall 82, a rear wall 84, a left hand end wall 86 and a right hand end wall 88, all of which co-operate to define open-topped box 78. Enclosure 22 may have a top wall, of which a viewing panel, such as window 26 may form a portion. In the embodiment illustrated, window 26 forms substantially the entirety of the top wall, and is set in a bezel, or external peripheral mounting frame, 90. Open topped box 78 has an upper rim, or frame, or lip, or peripherally extending flange 92 that mates with frame 90. A seal, such as an O-ring seal, 94 is captured between flanges 92 and frame 90. Window 26 may be provided with an optical filter, or smoked glass window panel 96. Panel 96 may be mounted on a pantograph, movable articulated arm, or on a set of rails 98 permitting x-y adjustment. Panel 96 is provided for use when the glove box 20 is being used for a welding activity or procedure. The front wall 82 or face of enclosure 22 most typically has the working access port or porting or penetrations 28, 30. Removable obstructing panels, or port covers 38 are provided on the inside of front wall 82, and may be pulled into place when retracting the gauntlets. Port covers 96 may be put in place, and sealed, when the air is evacuated from chamber 22 and a flushing atmosphere of an inert gas or CO2 is introduced. When chamber 22 is again at only a small pressure differential from ambient, port covers 96 are opened. External access 42 is mounted to one or the other of the left or right hand walls 86, 88. In this description, the choice of left or right is arbitrary. In the illustrations, access 42 is mounted to the right hand wall, there being a corresponding penetration trough the right hand wall. Access 42 could be mounted to the base wall or to the rear wall. In an event, access 42 as shown is, or includes an air-lock 100, having a generally rectangular body 102 having an external closure or hatchway or port 104 and an internal hatchway or port 106. Each of the internal and external hatches has an array of securements, indicated as clamps 108 by which to seal either end of the passageway through body 102. Body 102 has gas supply and evacuation fittings 110, 112. In operation, one port is opened; a work piece, or batch of work pieces, or tool, or consumable item such as an electrode, or box of electrodes, is placed inside the antechamber, or passageway, defined by body 102; the outside door is secured; air is evacuated from body 102 through evacuation fitting 112 and, typically, replaced by an inert gas, such as Argon, provided through fitting 110 to match the prevailing atmosphere within chamber 24. The interior port is then opened, and the objects are moved into the chamber 24. Where objects are to be removed, the procedure is reversed. In this way, objects can be introduced into chamber 24, or removed therefrom, without so frequently having to evacuate and purge chamber 24 using a vacuum pump and supplied inert or non-participating gases. This may tend to save time and gas consumption. Environmental control system 50 of chamber 24 may include main inlet and outlet 120, 122 fittings by which to introduce or to evacuate gases. Inlet fitting 120 may typically be connected to a gas manifold 114 connected to an inert gas cylinder (e.g., 70) or a typically non-participating gas, such as Nitrogen or CO2 (e.g., 72). Outlet fitting 122 may be a vent, where flushing relies merely on the relative buoyancy of gases, or it may be connected to a vacuum pump 116, where one gas is evacuated, or largely evacuated, before another gas is introduced The wall penetrations for these fittings may be located in the opposite end wall, namely left hand wall 86. There may be more than one such fitting, depending on the relative densities of the gases being introduced and extracted. In the manner of a submarine's ballast tanks, the lighter (i.e., less dense) fluid will be introduced or extracted at the top, and the heavier (i.e., more dense) fluid is extracted or introduced at the bottom. Environmental control system 50 may also include one or more internal heat exchangers 124 and an externally mounted heat exchanger 126, the two heat exchangers being connected by suitable piping, that piping passing through the wall structure of enclosure 22 at sealed wall penetrations. There may typically be a pump 128 to move a working fluid between the two heat exchangers. There may be a nozzle, and there may be check valves in the various lines to prevent backward flow. There may be an air mover, such as a fan or blower 130, located within chamber 24, an operable to urge flow of the internal atmosphere through heat exchanger 124. Similarly, there may be an external fan or blower 132 mounted to urge ambient air through external heat exchanger 126. External heat exchanger 126 may be mounted to undercarriage 44, or it may be mounted on a separate frame or stand. Environmental control system 50 may also include a more active heating or cooling system, such as a heat pump, typically a vapour cycle heat pump. In such a system, internal heat exchanger 124 would be an evaporator, and external heat exchanger 126 would typically be a condenser. In a further alternative, internal heat exchanger 124 may be supplied with a chilled (or, possibly, heated) liquid feed line, such as a cold water supply line, with heated return water being either discarded or cooled in heat exchanger 126. Workstand 48 of glove box 20 is an apparatus to which a workpiece can be mounted for processing. Workstand 48 may be, or may include, a flat plate, indicated as a tooling plate 140. Tooling plate 140 may have a clamp, or jig, or other fixture having or defining an accommodation or seat for the work piece. It may include an upstanding member 142, be it a wall or arm or frame directed toward that same end. Workstand 48, or any of its components, may be electrically conductive, or may have an electrical connection by which either direct or alternating current may be applied. Workstand 48 may include an array of threaded holes or profiled channels to which clamps or fasteners may be mounted, thereby to provide a securement for jigs, of fittings, or tool holders for the workpiece or for processing equipment or tooling. Furthermore, workstand 48 may be provided with cooling fittings, passages or galleries, indicated notionally as 142, by which, and through which, liquid coolant may be supplied. Such fittings may be connected to an external coolant source (e.g., a cold water tap) through yet another wall penetration. Workstand 48 may also be provided with a temperature sensor, or thermostat. A temperature control unit 144 may be mounted on rear wall 84, and is connected to operate the various elements of the environmental control system, as may be. There may also be a tool holder 146, in which to mount a tool such as a welding electrode holder. Tool holder 146 may be an adjustable, multiple-degree-of-freedom tool holder permitting variation of placement and orientation of the tool relative to the workpiece. Tools may also be hand held, and hand operated by the user. As indicated above, enclosure 22 is movably mounted to undercarriage 44. In the embodiment shown, enclosure 22 is hinged long its front edge at the tops of the left and right uprights 60. At the rearward end or edge of enclosure 22 are mounted a pair of left and right hand rods, or struts, or supports 150, 152, and corresponding clamps 154, 156. Left-hand and right-hand gas springs 158 are used to counter-balance enclosure 22. Supports 150, 152 may be rigid members, and may have the shape or profile of a sector of a circle. Enclosure 22 may be raised and lowered pneumatically, and, when adjusted, clamped in position by securing supports 150, 152 to the top frame side cross-members with clamps 154, 156. Enclosure 22 has a set of electrical control circuit interface fittings 160 mounted in left hand wall 86. Rather than making repeated openings in wall 86, several fittings may be mounted on a common plate, as at 146. An electrical control box is mounted to undercarriage 44 at 148. One use for glove box 20 may be for welding or other high temperature melting of fusing processes. To that end, a welding applicator, or handle, or electrode holder 162 may be provided inside chamber 24. Electrical power connections for holder 162 are provided through fittings 160, and may include multiple power sources, whether AC or DC, whether for providing a main welding current, or for powering accessories such as oscillator motors, sensors, controls, ventilators and so on. It may be expected that the electrode mounted in holder 162 will have opposite polarity to workstand 48. The use of glove box 20 permits the welding processes to occur in a controlled, typically non-oxidizing, atmosphere. Glove Box 20 has user-operable controls 56 located within chamber 24, within reach of gauntlets 32, 34 to permit the operator to adjust variable process parameters. Controls 56 may include controls to adjust voltage, current, discharge capacity, or discharge pulse duration. Control 56 may also include controls to adjust shielding gas flow, and chamber temperature. To the extent that either workstand 48 or holder 162 vibrates, controls 56 may include a frequency adjustment. Chamber 24 may have a supply rack in which alternate types of electrode rod are held. The voltage, current and charge suitable for different welding rod deposition materials may vary. The operator is then able to adjust between coating layers without removing the operator's hands from gauntlets 32, 34. Glove box 20 may include a duplicate set of controls 166 mounted outside enclosure 22. The operator may be able to determine the settings of the various controls 56 by feel inside chamber 24. Alternatively, or additionally, glove box 20 may have an external visual display 168, that is mounted outside chamber 24, and so protected from damage during a welding process, while still being visible to the operator. In the alternate embodiment of FIG. 7, the workstand, 170 is movably mounted to an internal ring 172 such that the angular orientation of workstand 170, and therefore of a workpiece mounted thereto, is variable. When the desired angle of tilt is obtained, workstand 170 may be clamped in a fixed orientation for processing using clamps 174. Thus enclosure 176 can be tilted to tilt the viewing angle of window 178, and the workpiece can also be tilted. In some circumstances the tilt may be such as to make the surface of workstand 170 horizontal and level notwithstanding that enclosure 176 is tilted. The adjustment mechanism may be motorized, and operable by the operator using either internal or external controls. Similarly, or additionally, in FIG. 8a and in the enlarged detail of FIG. 8b, the inside of chamber 24, including an angularly adjustable tool stand, or tool holder, or shelf 180, upon which to place, for example, tools, or additional work pieces, or welding electrodes or other consumable items so that they will not roll away. By their nature, when a glove box such as glove box 20 is to be used for an activity such as welding or brazing, where it is desired purge the usual ambient oxygen containing atmosphere, and to replace it with an inert or non-participating atmosphere instead, e.g., so as to reduce the likelihood on undesirable oxides contaminating the weld, the purging process may first require drawing a vacuum in the chamber to purge the air, and then introducing the desired non-participating gas to flush the chamber. Even with a large vacuum pump, this is typically quite a slow process involving a substantial transition time. If the operator wishes to process several work pieces per day, the rate of work may be reduced by the length of time it takes to purge and flush the chamber. Also, by its nature, a production process may involve the introduction of new work pieces and the removal of finished work pieces, as well as the introduction of consumables as processing occurs. It may also involve the introduction or changing of tools, such as welding electrode holder 162 shown in FIG. 10. The process may be hastened by reducing the volume to which vacuum extraction and gas purging may be applied. Further, the cost of supplying purging gases for a repetitive production process may not be insignificant over time. It may be possible to reduce both the turn-around time and the use of purging gases by reducing the volume to be evacuated, purged, and flushed. To that end, FIGS. 9a and 9b relate to a casing, or carrier, or transfer case, indicated generally as 200, and having first and second halves 202, 204. Carrier 200 has external length, width, and depth dimensions closely corresponding to the inside length, width, and depth of the antechamber, or air lock 100. First and second halves 202, 204 are provided with respective internal cavities 206, 208, 210, 212. Cavities 206 and 208 may combine to form a female mold, or cavity, corresponding closely to the shape of a work piece to be processed. Cavities 210, 212 may correspond to the shape of tools or consumables to be used in processing the corresponding workpiece. Transfer case 200 is not sealed, and cavities 206, 208, 210 and 212 communicated with the outside, such that when air lock 100 is purged, cavities 206, 208, 210 and 212 are also purged. By occupying the balance of the volume of air lock 100, transfer case 200 reduces the time required to purge the air lock, and the amount of inert or non-participating gas that must be used to purge the chamber. Transfer case halves 202, 204 have external grips, or bails, or handles 214, 216 which permit them to be opened. Handles 214, 216 may be spring mounted and may seat in external recesses such that they lie shy of the outside profile of the sides of transfer case 200, thereby allowing the outsides of the box to fit more closely in air lock 100. Although only one pair of workpiece cavities 206, 208 is shown, it may be that a process may be more efficient, in terms of both transition time and gas use where carrier 200 has accommodations for several work pieces. In use, one batch of work-pieces can be introduced, and placed on shelf 180, while another batch of finished work-piece can be placed in the now-empty cavity, or cavities, of transfer case 200. Similarly, cavities 210, 212 may be used to introduce enough consumable materials, such as electrodes, for several work pieces, and may include work pieces of different compositions, corresponding to different coating layers. That is, it may be that in coating one type of substrate, be it steel or copper or some other material, it may be desirable to start with a first coating layer. That first coating layer may be of nickel, for example. The first coating layer may be followed by a second coating layer, of a different material, be it a carbide, such as titanium carbide or titanium di-boride; or it may be another metal layer such as a layer of molybdenum. There may be a third layer, or such additional layers as may be, of yet different composition, or compositions. Various coating materials may be used according to the desired process and the desired final finish properties. The use of transfer case 200 may tend to permit these processes to occur with less volumetric exchange. The embodiments illustrated and described above illustrate individual non-limiting examples in which the principles of the present invention are employed. It is possible to make other embodiments that employ the principles of the invention and that fall within the following claims. To the extent that the features of those examples are not mutually exclusive of each other, the features of the various embodiments may be mixed-and-matched, i.e., combined, in such manner as may be appropriate, without having to resort to repetitive description of those features in respect of each possible combination or permutation. The invention is not limited to the specific examples or details which are given by way of illustration herein, but only by the claims, as mandated by law. The claims are to be given the benefit of purposive interpretation to include equivalents under the doctrine of equivalents. Although the various embodiments have been illustrated and described herein, the principles of the present invention are not limited to these specific examples which are given by way of illustration, but only by a purposive reading of the claims.
	claims	1. An irradiation target retention system comprising:at least one irradiation target retention device,dimensioned and shaped to fit within a nuclear fuel rod such that a central axis of the at least one irradiation target retention device is parallel to a longitudinal axis of the fuel rod in which the at least one irradiation target retention device is dimensioned and shaped to fit,fabricated of a material configured to substantially maintain its physical and neutronic properties when exposed to the neutron flux in the operating nuclear reactor, andindividually defining each of a plurality of bores, each of the bores being defined with a bottom in the irradiation target retention device in a direction of the central axis of the irradiation target retention device such that the bores do not pass entirely through the irradiation target retention device in the direction of the central axis of the irradiation target retention device, each of the bores being offset from the central axis of the irradiation target retention device; andat least one irradiation target contained in the irradiation target retention device by one of the bores, the irradiation target configured to substantially convert to a radioisotope when exposed to a neutron flux in an operating nuclear reactor. 2. The system of claim 1, wherein the at least one irradiation target retention device includes a cap configured to attach to an end of the irradiation target retention device having the at least one bore, the attaching of the cap and the device configured so as to retain the irradiation target within the at least one bore. 3. The system of claim 1, wherein the irradiation target is at least one of Iridium-191 and Cobalt-59. 4. The system of claim 1, a central axis for each of the bores is placed at an equal radial distance from the central axis of the irradiation target retention device. 5. The system of claim 4, wherein the at least one irradiation target retention device further defines at least one hole passing entirely through the irradiation target retention device, a central axis for the hole being located at the equal radial distance from the central axis of the irradiation target retention device. 6. The system of claim 5, wherein the at least one irradiation target retention device includes a keyed slit positioned about the central axis of the irradiation target retention device and passing through the irradiation target retention device, the keyed slit having a unique orientation with respect to the at least one hole. 7. The system of claim 1, wherein the irradiation target retention device is fabricated from at least one of a zirconium alloy, stainless steel, aluminum, nickel alloy, and Inconel. 8. A nuclear fuel assembly comprising:an upper tie plate;a lower tie plate; anda plurality of fuel rods extending between the upper tie plate and lower tie plate, at least one fuel rod including at least one irradiation target retention device including,a plurality of irradiation targets contained within a bore defined by the irradiation target retention device, the bore being offset from a central axis of the irradiation target retention device by a distance, the bore being defined with a bottom in the irradiation target retention device in a direction of the central axis of the irradiation target retention device such that the bore does not pass entirely through the irradiation target retention device in the direction of the central axis of the irradiation target retention device, the irradiation targets configured to substantially convert to a radioisotope when exposed to a neutron flux in an operating nuclear reactor,the irradiation target retention device including a hole passing entirely through the irradiation target retention device, a central axis of the hole being offset from the central axis of the irradiation target retention device by the distance,the irradiation target retention device dimensioned to fit within the at least one fuel rod, andthe irradiation target retention device fabricated of a material configured to substantially maintain its physical and neutronic properties when exposed to the neutron flux in the operating nuclear reactor. 9. The nuclear fuel assembly of claim 8, wherein the irradiation targets include at least one of Iridium-191 and Cobalt-59. 10. The nuclear fuel assembly of claim 8, wherein the at least one fuel rod includes a plurality of irradiation target retention devices axially stacked within the at least one fuel rod. 11. The nuclear fuel assembly of claim 10, wherein the at least one fuel rod further includes a spring configured to compress the axially stacked plurality of irradiation targets within the at least one fuel rod with a force such that the irradiation target is sealed in the at least one bore. 12. The nuclear fuel assembly of claim 10, wherein the irradiation target retention device individually defines each of a plurality of bores and a central axis of each of the bores is placed at the equal radial distance from the central axis of the irradiation target retention device. 13. The nuclear fuel assembly of claim 8, wherein the irradiation target retention device further includes a keyed slit positioned about the central axis of the irradiation target retention device and passing through the irradiation target retention device, the keyed slit having a unique orientation with respect to the at least one hole. 14. The nuclear fuel assembly of claim 8, wherein the irradiation target retention device is fabricated from at least one of a zirconium alloy, stainless steel, aluminum, a nickel alloy, and Inconel. 15. The nuclear fuel assembly of claim 8, wherein the at least one irradiation target retention device includes a cap configured to attach to an end of the irradiation target retention device having the at least one bore, the attaching of the cap and the device configured so as to retain the irradiation target within the at least one bore. 16. The system of claim 1, wherein the material does not substantially interfere with the neutron flux. 17. The nuclear fuel assembly of claim 8, wherein the material does not substantially interfere with the neutron flux.
	description	This application claims the benefit under 35 U.S.C. § 119(e) of U.S. Provisional Application No. 60/909,431, filed on Mar. 31, 2007, the entire contents of which are incorporated herein by reference. 1. Technical Field Example embodiments relate to the production and extraction of radioisotopes from a source compound. 2. Description of the Related Art Therapeutic radiopharmaceuticals may be radiolabeled molecules used for delivering therapeutic doses of ionizing radiation with relatively high specificity to certain disease sites (e.g., cancerous tumors) in a patient's body. Additionally, recent research has been directed to the radiolabeling of monoclonal antibodies to evaluate the efficacy of radioimmunotherapy. A number of different radioisotopes have been used for these purposes, including α, β, and auger electron emitters. For those applications including site-specific therapy, it may be beneficial to use radiopharmaceuticals exhibiting higher specific activities. However, the presence of “cold” labeled antibodies may decrease the number of “hot” labeled antibodies that occupy the binding sites on the target cells. Consequently, reduced numbers of “hot” labeled antibodies may result in lower doses of ionizing radiation to the target cells, thus decreasing or impeding the ability of the treatment to induce the desired cell kill. Accordingly, higher specific radioactivity (SA) compounds may be beneficial to reduce the impact of “cold” labeled antibodies. 186Re has been investigated as a candidate for radiotherapy, because 186Re decays by β-emissions and has a half-life of about 3.7 days. Additionally, 186Re exhibits a chemical similarity to 99mTc, a radioisotope that has already been extensively studied and used in a variety of medical applications. 186Re may be produced in reactors via an 185Re(n, γ)186Re reaction. Although radioimmunotherapy using 186Re has been successfully performed, higher SA 186Re compounds remain relatively difficult to obtain. A method of isolating a radioisotope for production of a higher specific activity radiopharmaceutical according to example embodiments may include vaporizing a source compound containing a first isotope and a second isotope, wherein the second isotope may be a radioisotope having therapeutic and/or diagnostic properties. The vaporized source compound may be ionized to form negatively-charged molecules containing the first isotope and the second isotope. The negatively-charged molecules may be separated by mass to isolate the negatively-charged molecules containing the second isotope. The isolated negatively-charged molecules containing the second isotope may be collected with a positively-charged collector. A method of isolating 186Re according to example embodiments may include vaporizing a source compound containing 185Re and 186Re. The vaporized source compound may be ionized to form negatively-charged molecules containing 185Re and 186Re. An electric field may be generated to extract and accelerate the negatively-charged molecules away from the ion source. Additionally, a magnetic field may be generated to draw excess free electrons away from the negatively-charged molecules. The negatively-charged molecules may be separated by mass to isolate the negatively-charged molecules containing 186Re. The isolated negatively-charged molecules containing 186Re may be collected with a positively-charged collector. It will be understood that when an element or layer is referred to as being “on”, “connected to”, “coupled to”, or “covering” another element or layer, it may be directly on, connected to, coupled to, or covering the other element or layer or intervening elements or layers may be present. In contrast, when an element is referred to as being “directly on,” “directly connected to” or “directly coupled to” another element or layer, there are no intervening elements or layers present. Like numbers refer to like elements throughout the specification. 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, although the terms first, second, third, etc. may be used herein to describe various elements, components, regions, layers and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another region, layer or section. Thus, a first element, component, region, layer or section discussed below could be termed a second element, component, region, layer or section without departing from the teachings of example embodiments. Spatially relative terms, e.g., “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the term “below” may encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. The terminology used herein is for the purpose of describing various 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” and/or “comprising,” when used in this specification, 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. Example embodiments are described herein with reference to cross-sectional illustrations that are schematic illustrations of idealized embodiments (and intermediate structures) of example embodiments. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, example embodiments should not be construed as limited to the shapes of regions illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, an implanted region illustrated as a rectangle will, typically, have rounded or curved features and/or a gradient of implant concentration at its edges rather than a binary change from implanted to non-implanted region. Likewise, a buried region formed by implantation may result in some implantation in the region between the buried region and the surface through which the implantation takes place. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the actual shape of a region of a device and are not intended to limit the scope of example embodiments. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments belong. It will be further understood that terms, including those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein. Example embodiments relate to the production and isolation of anionic species from a source material. For instance, the methods according to example embodiments may be suitable for producing and isolating 186Re (rhenium-186) radioisotopes. As a result, higher specific radioactivity compounds containing the 186Re radioisotopes may be generated. The 186Re compounds may be utilized in a variety of medical applications. For example, an 186Re compound may be attached to one or more antibodies that are specific to the targeted receptors and utilized in radiation therapy and/or diagnostic procedures. The methods and apparatuses according to example embodiments may also be suitable for producing other higher specific radioactivity materials which may be utilized in a broader range of research, therapeutic, and/or diagnostic applications. Conventional methods of producing 186Re may utilize 185Re (rhenium-185) or 186W (tungsten-186) as the starting material. The conventional method utilizing 185Re as the starting material may be represented by expression (1) below:185Re(n,γ)186Re (1)wherein the 185Re is converted to 186Re through neutron capture in a reactor. Although this method may have relatively high yield, separating the desired 186Re isotope from the source material may be difficult (e.g., via chemical separation), thus resulting in products exhibiting relatively low specific radioactivity. The conventional method utilizing 186W as the starting material may be represented by expression (2) below:186W(p,n)186Re (2)wherein the 186W is converted to 186Re through a proton induced reaction within a particle accelerator. Although this method may have in a relatively low yield, separating the desired 186Re isotope from the source material may be easier (e.g., via chemical separation), thus resulting in products exhibiting improved levels of specific radioactivity. However, because the cross-section for the 186W(p,n)186Re reaction is relatively low, producing patient-dose quantities of 186Re in a cost effective manner using this method may not be feasible. Additionally, a relatively large number of curies of therapeutic and/or diagnostic radioisotopes may be required for clinical trials. Accordingly, an accelerator-based 186W production method may not even be able to produce the necessary quantities of therapeutic and/or diagnostic radioisotopes for a single patient per day (let alone thousands of patients yearly). The methods and apparatuses according to example embodiments may involve the ionization and mass separation of 186Re from the 185Re starting material so as to facilitate the production of increased specific radioactivity 186Re compounds. The methods and apparatuses according to example embodiments may be able to achieve radioisotope production in the range of curies per day of material exhibiting relatively high specific radioactivity values (e.g. above 30 curies/mg). As discussed above, conventional 186Re therapeutic and/or diagnostic compounds produced by neutron capture in a reactor may have relatively low specific radioactivity. Consequently, increases in the specific radioactivity of 186Re compounds according to example embodiments may be investigated to determine to the level of specific radioactivity required to improve therapeutic and/or diagnostic efficacy relative to that of conventional 186Re compounds. Once a target specific radioactivity has been established (e.g., the antibody-conjugated 186Re according to example embodiments exhibits improved efficacy over the conventional lower specific radioactivity 186Re while maintaining acceptable specificity so as to reduce or avoid impacting cells that do not express the target cell surface marker), methods and apparatuses according to example embodiments may be employed to produce usable quantities of the 186Re compound having the target specific radioactivity via ionization and mass separation of the 186Re radioisotope. The increased availability of 186Re compounds having higher specific radioactivity may facilitate further chemical developments and clinical studies directed to the use of 186Re-radiolabeled antibodies or small molecules. Labeling an antibody with 186Re produced and recovered according to example embodiments may involve utilizing an activated ester as a bifunctional chelating agent (e.g., mercaptoacetyltriglycine (MAG3)). An example of a reaction scheme for the synthesis of the activated ester may be shown below by scheme (3). Although 188Re may be available in no-carrier-added form via a 188W generator, 186Re may be the more suitable radioisotope, at least with regard to matching the physical decay properties of the radioisotope with the cell repair cycle. For example, the decay properties of 186Re may include a β-Emax of about 1 MeV and a t1/2 of about 90 h, while the decay properties of 188Re may include a β-Emax of about 2 MeV and a t1/2 of about 17 h. Thus, the decay properties of 186Re may be more suited for the radioisotope therapy of small tumors. Additionally, generation of the 188W precursor (for 188Re production) involves a double neutron capture reaction which can be achieved at only a few reactors worldwide, while facilities capable of the 185Re(n,γ)186Re reaction are much more widely available. According to example embodiments, higher specific radioactivity 186Re compounds may be generated with greater ease from the 185Re(n,γ)186Re reaction product. Furthermore, 186Re compounds according to example embodiments may exhibit improved physical properties with regard to energy and half-life relative to 90Y and 131I, respectively, wherein 90Y and 131I are commonly used radioisotopes. The methods and apparatuses according to example embodiments relate to the production of increased specific radioactivity 186Re compounds. Additionally, the specific radioactivity of the 186Re compounds may be adjusted via the inclusion of natural rhenium so as to achieve a level of specific radioactivity that exhibits the desired balance of therapeutic and/or diagnostic efficacy and value. As discussed above, 186Re may be a suitable candidate for radiotherapy, because its decay properties include β-emissions and a half-life of about 3.7 days. Furthermore, 186Re has a chemical similarity to 99mTc, which has already been extensively studied. However, although production facilities capable of producing 186Re via the 185Re(n,γ)186Re reaction may be readily available, the conventional 185Re(n,γ)186Re reaction method typically results in a 186Re product exhibiting relatively low specific radioactivity which limits its utility in therapeutic and/or diagnostic applications involving site-specific targets. To improve the production of higher specific radioactivity 186Re compounds, methods and apparatuses according to example embodiments may employ a cusp ion source to ionize and extract the 186Re radioisotopes from the starting material. Additional information regarding cusp ion source technology may be found, for example, in Dehnel, et al., NIM B, vol. 241, pp. 896-900, 2005, the entire contents of which are incorporated herein by reference. FIG. 1 is an electrical schematic diagram of a rhenium ion source according to example embodiments. Referring to FIG. 1, plasma may be generated by electron emission from the filament 100 at a current of about 130 Amps. The plasma may be maintained in a stable state by the addition of hydrogen (H2) gas. As a result, the majority of the ions implanted into the Faraday cup 102 may be H− ions. The extraction lens 104 (e.g., 2 kV) and Faraday cup 102 (e.g., 20 kV Bias) may be maintained at a positive voltage so as to extract negative ions from the source. It should be understood that the rhenium ion source according to example embodiments is not limited to the parameters set forth in FIG. 1. Rather, one of ordinary skill in the art will readily appreciate that, in view of the present disclosure, other variations are possible. Using the example discussed above, initial tests may be conducted to determine the temperature of the plasma as a function of the resistance of resistor R2. As the filament current is increased, the arc across the plasma may also increase. The resistor R2 may limit the feedback between these two power supplies, so it may be beneficial to determine the highest resistance of the resistor R2 that will allow the maintenance a temperature that is sufficiently high to keep a rhenium oxide species volatile. A graph of this plasma temperature change with resistance is shown in FIG. 2. In light of the results shown in FIG. 2, the R2 resistor value may be maintained at about three ohms to ensure adequate vaporization. However, in view of the present disclosure, those of ordinary skill in the art will readily appreciate that a variety of circuits and apparatuses may be used to achieve the target plasma heating and that such modifications would not detract from the fundamental operation of the disclosed device. In a method according to example embodiments, H188ReO4 was utilized as the radioisotope source compound. The H188ReO4 was collected on a quartz dish, dried, and placed in the ion source chamber. The pressure in the ion source chamber was reduced to below atmospheric pressure, and hydrogen plasma was produced within the ion source chamber. Consequently, the plasma heated the radioisotope source compound to a temperature sufficient to induce vaporization of the source compound. As the molecules of the source compound vaporized and interacted with the plasma (e.g., H− ions), negatively charged species were produced and accelerated toward the collector assembly. In this instance, the collector assembly was a Faraday cup, although example embodiments are not limited thereto. Without being bound by theory, it is believed that the H− plasma interacts with the radioisotope source compound to produce one or more negatively charged ions (e.g., ReOn−) which are accelerated toward and collected in the Faraday cup. As will be appreciated by those ordinarily skilled in the art, this technique may also be applicable to other radioisotope source compounds (e.g., oxides, nitrides, carbides) which can be vaporized under the appropriate temperature and pressure combination maintained within the ion source chamber. Similarly, those ordinarily skilled in the art will also appreciate that the proper temperature and pressure may be a function of the materials utilized, the power applied, and the configuration of the source chamber and the ancillary equipment (e.g., gas mass flow controllers, valving, control systems, vacuum pumps, cooling assemblies). The ion source chamber according to example embodiments may be constructed and operated so as to enable the creation and maintenance of the appropriate temperature and pressure conditions within the ion source chamber. As a result, the radioisotope source material may be vaporized at a suitable rate without damaging the ion source chamber or generating undesirable levels of byproducts that would interfere with the collection and enrichment of the targeted radioisotope. For example, the radioisotope source compound utilized in the ion source may exhibit satisfactory vaporization at temperatures below about 1300° C. Additionally, it may be beneficial for the radioisotope source compound to exhibit satisfactory vaporization at temperatures below about 900° C. so as to allow for the utilization of a wider range of materials in the construction of the ion source chamber. Furthermore, it may be beneficial for the radioisotope source compound utilized in the ion source to exhibit satisfactory vaporization at pressures below about 1 Torr. As discussed above, the use of an appropriately sized R2 resistor according to example embodiments may allow the production of plasma capable of heating the source compound and its vessel to temperatures in excess of about 500° C., thereby volatilizing the rhenium oxide. Consequently, the source compound may dissociate within the plasma, with the resulting fragments becoming negatively charged ions (e.g., ReOn−). The negatively charged ions may be extracted from the ion source chamber and implanted on the Faraday cup. After an implant cycle, the Faraday cup may be removed and evaluated using gamma spectroscopy to determine the amount of radioactivity implanted in the Faraday cup. Ion source performance analysis indicates that the apparatus illustrated in FIG. 1 may achieve implant beam currents of about 1.2 mA (with H− constituting a major portion of the beam and the radioisotope source compound species ReOn− constituting a minor portion of the beam). FIG. 3 is a photographic image of a Faraday cup after one hour of irradiation with the extracted Re beam according to example embodiments. Because the power of the accelerated beam exceeded the tolerance of the Faraday cup based on its initial configuration, the Faraday cup became discolored and deformed, as shown in FIG. 3. When the Faraday cup and the source compound container from the ion source chamber were analyzed with a high purity Germanium detector for radioactivity, the initial results indicated that approximately 20% of the radioactivity that was volatilized from the source was actually implanted in the Faraday cup. Additional efforts may be directed toward improving the extraction percentage, wherein the extraction percentage may be the portion of the desired rhenium radioisotopes released from the source compound vessel (e.g., quartz dish). For example, by providing a combination of both stable and radioactive rhenium atoms on the source compound vessel used in the ion source chamber, the majority of the radioisotope atoms may be successfully vaporized, ionized, and collected at the target assembly (e.g., a Faraday cup). As will be appreciated by those ordinarily skilled in the art, various combinations of stable and radioactive rhenium atoms and extraction voltages may provide for further improvements in the extraction percentage. FIG. 4 is a plan view, side view, and perspective view of a water-cooled Faraday cup for a rhenium ion source according to example embodiments. A modified apparatus incorporating a water-cooling arrangement 106 for the Faraday cup 102 may reduce the damage suffered by the Faraday cup 102 during implantation. For example, the water-cooled Faraday cup 102 may be beneficial during prolonged implants and may increase the removability of the radioactivity from the source. The methods and apparatuses according to example embodiments may facilitate the production of useful quantities of increased specific radioactivity 186Re and related compounds. For example, a 186Re source compound may be placed in an ion source chamber and exposed to a temperature and pressure combination that is sufficient to induce the vaporization of the source compound. Hydrogen plasma may be utilized to both heat the source compound and to ionize the resulting molecular fragments to produce Re-containing anions. The Re-containing anions may be extracted from the ion source chamber and collected in a positively-charged target vessel. As will be appreciated by those ordinarily skilled in the art, alternative configurations may provide for supplemental heating sources. For example, resistance heating and/or microwave heating may be used in lieu of or in addition to the plasma for vaporizing the source compound. Similarly, alternative structures (e.g., higher voltage filaments) may be utilized for imparting a negative charge to the vaporized source compound fragments so that the desired species (e.g., radioactive species) may be extracted from the ion source chamber and accelerated toward a collection assembly. Furthermore, the source compound may be introduced into the ion source chamber as a vapor (e.g., perrhenic acid). Thus, when properly configured according to the present disclosure, various alternative example embodiments may be attained for purposes of producing higher specific radioactivity compounds. Depending on the separation assembly (e.g., magnetic separation assembly), specific radioactivity values in the range of 30 curies/mg to over 300 curies/mg may be achieved using the methods and apparatuses according to example embodiments. As discussed above, a CUSP ion source may be used to separate 186Re from neutron-irradiated 185Re by ionizing perrhenate molecules and implanting them on a water-cooled Faraday cup. The CUSP ion source may provide satisfactory results even when the perrhenate ion beam is not controlled and is contaminated with a relatively high current negative ion hydrogen beam. Alternatively, a negative ion surface thermal ionization (NIST) process may be utilized to ionize the perrhenate molecules. Depending on the circumstances, negative ion surface thermal ionization may be more efficient and effective than CUSP ionization. Methods and apparatuses according to example embodiments with regard to negative surface ionization are described below. Furthermore, additional information relating to surface ionization may be found in Brown, Ian G. (Ed.), “The Physics and Technology of Ion Sources,” 2nd edition, Wiley-VCH, Weinheim, 2004, the entire contents of which are incorporated herein by reference. When a neutral atom or molecule impinges upon and is temporarily adsorbed by a heated surface during a negative ion surface thermal ionization (NIST) process, the heated surface may be hot enough to prevent the atoms from remaining adsorbed. As a result, the atoms or molecules may be ionized when leaving the heated surface. A negative ion may be produced when the work function (Φ) of the heated surface is smaller than the electron affinity (EA) of the atom or molecule impacting the heated surface. For example, referring to FIG. 5, when approaching a relatively hot surface 500, an atom/molecule 502 may become polarized by the forces between its nucleus and the free electrons inside the relatively hot surface 500. The atom/molecule 502 may adhere to the relatively hot surface 500 under the action of these forces. If the work function (Φ) of the relatively hot surface 500 is smaller than the electron affinity (EA) of the absorbed atom/molecule 502, then an electron 504 at the Fermi level in the conduction band of the relatively hot surface 500 may shift by tunneling to the electron affinity level of the atom/molecule 502. Consequently, there may be a probability that the adsorbed atom/molecule 502 will transition from a neutral state to a negative ionic state. If the temperature of the relatively hot surface 500 is sufficiently high, then the adsorbed atom/molecule 502 may accumulate enough energy to overcome the binding forces so as to result in thermal desorption. During thermal desorption, the adsorbed atom/molecule 502 may be ejected as an ion 506 with relatively low energy from the relatively hot surface 500. The likelihood of ionization may be described as a function of the surface temperature, the work function of the surface material, and the electron affinity of the atom/molecule to be ionized. The probability that a negative ion will be emitted may be mathematically expressed by a set of equations. For example, the equilibrium ratio (α) of ion flux (N−) to neutral flux (Nn) leaving from the heated surface may be provided by the Saha-Langmuir (S-L) equation as shown by equation (4) below: α ⁢ = N - N n = g - g n ⁢ exp ⁡ [ q ⁡ ( EA - Φ ) kT ] ( 4 ) wherein: N−=emission rate of negative ions Nn=emission rate of neutral species φ=work function of the surface [eV] EA=electron affinity of atom or molecule [eV] k=Boltzmann's constant (8.617×10−5 eV/K) T=absolute surface temperature [K] g−,=statistical weighting factors for the negative ion and neutral gn atom/molecule, respectively. They are related to the total spin S of the respective species given by g = 2 ⁢ ⁢ S + 1 = 2 ⁢ ∑ i ⁢ s i + 1 ,wherein si is the spin on the ith electron The ionization efficiency (β) may be in equilibrium when the total number of particles (N0) is equal the sum of N−+Nn. The ionization efficiency (β) may be expressed by equation (5) below: β = α 1 + α = N - N 0 = 1 1 + g n g - ⁢ exp ⁡ ( q ⁡ ( Φ - EA ) kT ) ( 5 ) wherein: N−=emission rate of negative ions Nn=emission rate of neutral species φ=work function of the surface [eV] EA=electron affinity of atom or molecule [eV] k=Boltzmann's constant (8.617×10−5 eV/K) T=absolute surface temperature [K] g−,=statistical weighting factors for the negative ion and neutral gn atom/molecule, respectively. They are related to the total spin S of the respective species given by g = 2 ⁢ ⁢ S + 1 = 2 ⁢ ∑ i ⁢ ⁢ s i + 1 ,wherein si is the spin on the ith electron In view of the above equations, it may be appreciated that higher temperatures may have higher ionization potential. Additionally, it may be appreciated from equation (6) below that the residence time (τ) of the impinging particle may be reduced with higher temperature. τ = τ 0 ⁢ exp ⁡ ( E ads kT ) ( 6 ) wherein: Eads=ion adsorption energy [eV] τ0=vibrational period of the ion near the surface [s] k=Boltzmann's constant (8.617×10−5 eV/K) T=absolute surface temperature [K] The ion adsorption energy (Eads) may a few eV, and τ0 may be about 10−13 s. The ionization probability may be independent of the initial kinetic energy as long as the initial kinetic energy is smaller than or comparable to the adsorption energy, because the residence time (τ) on the heated surface may be sufficient to ensure thermal equilibrium with the heated surface. A negative surface ion source apparatus according to example embodiments may include an evaporation unit, a vacuum system, an ionization unit, and an extraction unit. The extraction unit may include magnets for removing excess electrons. Ionization and extraction according to example embodiments may include transferring a 185/186Re mixture into a crucible and inserting the crucible into the evaporation unit. A vacuum may be established in the evaporation unit. The perrhenate molecules of the 185/186Re mixture may be evaporated under a vacuum. The perrhenate molecules then may be ionized in the ionization unit. The resulting perrhenate ions may be extracted from the ionization unit as a beam, wherein the beam may be shaped for injection into a mass separator to separate the 185Re from the 186Re. A method of isolating 186Re according to example embodiments will be discussed in further detail below. An irradiated chemically-undefined 185/186Re mixture may be chemically converted into a perrhenate salt (different counter ions are suitable). The perrhenate salt may be dissolved in water and transferred to a vaporization crucible. The water may be completely evaporated from the crucible, such that the 185/186Re perrhenates may be adhered to the walls of the crucible. The crucible may be made of a refractory material with a relatively low work function. For example, the crucible may be formed of tungsten (W), molybdenum (Mo), tantalum (Ta), or Lanthanum-Hexaboride, although example embodiments are not limited thereto. The cavity of the crucible may be comprised of a hollow cylinder with one side closed and the opening directly attached to the vaporization unit. The inner diameter and depth of the cavity may be in the mm to cm range and may be adjusted as needed. The crucible may be disposed in a filament of the evaporation unit for ohmic heating. After the crucible with the perrhenate has been inserted into the filament of the evaporation unit, a vacuum may be established (e.g., about 10−5 to 10−7 Torr). The crucible may be heated to a temperature of about 1500° C. After evaporation, the volatile perrhenates may drift into the ionization unit. The temperature of the ionization unit may be controlled separately. The ionizer may be made of a refractory material with a relatively low work function. The ionizer may have a tubular shape. The ionizer may also be filled with a porous material or a screen so as to enhance the ionizing process by increasing the surface area. The ionizer may be ohmically heated by a filament up to temperatures of about 1500° C. It may be beneficial for the transition connection between the evaporator and the ionizer to be relatively tight so as to reduce or prevent the loss of the volatile perrhenates. The transition connection may also provide thermal insulation between the evaporator and the ionizer to allow independent control of the evaporation and ionizing processes. Upon operation of the ion source, a plasma including of an equilibrium of volatile ionized and neutral perrhenates may be generated in the ionizer volume. An excess of free electrons, formed during the ionization process, may also be present. To reduce or prevent further acceleration of the excess free electrons, a relatively weak magnetic field may be established at the “exit” of the ionizer to draw the excess free electrons towards the screening electrode. The negatively ionized species may be accelerated from the ionizer by an electric field produced by a series of extraction electrodes having different voltage levels. The perrhenate ions and the excess free electrons may be initially accelerated from the ionizer region by the extraction electrode. The perrhenate ions may then be further accelerated and shaped by the screening electrode, whereas the excess free electrons (which have smaller mass) will hit the screening electrode and so be removed from the perrhenate ion beam. The final extracted perrhenate ion beam may be additionally shaped by magnetic and/or electrostatic beam optics and then injected into a mass separator to separate the 185Re from the 186Re. Although the example embodiments detailed above are directed to the production of higher SA 186Re compounds, the present disclosure is not limited thereto. For instance, the methods and apparatuses described above may be applied to the extraction of other radioisotope species (e.g., 99Mo compounds) that can be vaporized and negatively charged within an ion source chamber constructed and operated in accord with the detailed description provided above. Accordingly, the methods and apparatuses according to example embodiments may be utilized to produce an increased volume of a range of higher SA radioisotope materials having a longer shelf life and improved therapeutic and/or diagnostic effects compared to conventional production and purification techniques. While example embodiments have been disclosed herein, it should be understood that other variations may be possible. Such variations are not to be regarded as a departure from the spirit and scope of example embodiments of the present disclosure, 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.
052672913	summary	This invention relates to boiling water nuclear reactor fuel bundles and their fuel rod spacers and channels. More particularly, a fuel rod spacer with a surrounding band is disclosed in which sizing of the band at protrusions with respect to the immediately surrounding channel occurs to maintain the optimum clearance between the peripheral fuel rods within the fuel bundle and the channels of the fuel rods. Improved critical power performance results. BACKGROUND OF THE INVENTION Boiling water nuclear reactors have reactor cores composed of two moderator flow regions. These regions include the flow region through the reactor core and the flow region through the so-called core bypass region. In understanding these flow regions, the construction of the regions will first be set forth. Thereafter, the thermal hydraulic and nuclear characteristics of both regions will be discussed. The reactor core includes a plurality of side-by-side fuel bundles, these bundles being square in section and vertically elongate in dimension. The fuel bundles each include a matrix of sealed and vertically upstanding fuel rods supported on a lower tie plate. The lower tie plate serves to admit water moderator through the bottom of the fuel bundle about the rods for steam generation. A upper tie plate typically fastens to at least some of the fuel rods and permits the exit of water and generated steam from the fuel bundle. A channel surrounds the lower tie plate, the upper tie plate and the fuel rods therebetween. This channel serves to confine the flow path through the fuel bundle. At the same time, this channel and its flow path separate the fuel bundle flow interior of the channel from the core by-pass region exterior of the channel. So-called fuel rod spacers are placed at selected vertical intervals along the length of the fuel bundle. These spacers maintain the otherwise long a flexible fuel rods from coming into abrading contact one with another under the dynamics of fluid flow within the reactor as well as to maintain the designed fuel rod to fuel rod spacing for optimum nuclear performance. This being the case, each fuel rod spacer defines a matrix position for each fuel rod at the particular elevation of the spacer. Each fuel rod is confined by the spacer to a designed spaced apart position with respect to all of the adjacent fuel rods. The spacers are typically surrounded at a band. It is the function of this band to provide an outer defining envelope for the spacer cells into which fuel rods can be placed. Assembly of the fuel bundle can be summarized. Typically the lower tie plate and spacers are placed in their final spatial relation. Thereafter the fuel rods are threaded through the spacers at each matrix position and registered to the lower tie plate. Thereafter the upper tie plate is fitted over the assembly. Finally, the fuel bundle has the channel placed over its exterior surface. The operation of the fuel bundle from the thermal hydraulic stand point can be simply stated. Water moderator coolant is inlet from the bottom of the fuel bundle through the lower tie plate. Increasing fractions of vapor are generated as the moderator passes upwardly within the channel between the fuel rods through the fuel bundle with exit of the water and generated steam at and through the upper tie plate at the top of the fuel bundle. Operation of the fuel bundle from the nuclear stand point can likewise be simply stated. The water moderator within and about the fuel bundle takes the fast neutrons generated by the atomic reaction and slows or thermalizes these neutrons when the neutrons pass through the moderator. In the slow or thermalized state, the neutrons are capable of promoting the continuous chain reaction required to keep the reactor operating. It is to be understood that the density of the water moderator is an important factor in allowing the nuclear reaction to continue. Where the moderator is relatively dense--as for example where it consists of pure water--the fast neutrons are rapidly thermalized and the reaction abundantly continues. Where the moderator is not dense and contains large vapor fractions--the fast neutrons are not rapidly thermalized and among other things the reaction is not as abundant in its continuation. Having summarized the operation of the fuel bundles, the construction of the core bypass region can now be set forth. Simply stated, the core bypass region is defined by the exterior of the fuel bundles as they are arrayed within the reactor core in spaced apart side-by-side relation. As the square sectioned fuel bundles are placed together, they are spaced apart so as to define cruciform sectioned (that is "cross shaped") interstitial spaces. These spaces interconnect in a continuous matrix between all the fuel bundles. This interconnected matrix defines the core bypass region. This region accommodates the reactor control blades during reactor shut down and is flooded with water during reactor operation. The function of the reactor control blades is well known. These control blades are typically cruciform sectioned members. These cruciform sectioned members typically fit interstitially in the complimentary shaped cruciform core bypass region defined by the adjacent but spaced apart fuel bundles. When the cruciform shaped control blades are inserted to the cruciform shaped interstices between the fuel bundles of the core bypass region, they control and even shut down the nuclear reaction. The control blades in a boiling water reactor are typically inserted from below the reactor between the fuel rods displacing water in the core bypass region and absorbing the thermal neutrons. The function of the core bypass region during operation is also well known. The control rods are in large measure withdrawn. Water occupies this region immediately upon control rod withdrawal and immediately adjoins the fuel bundles at the channel walls. The water is on the outside of the channel walls; the fuel is on the inside of the channel walls. The water in this core bypass region--when not displaced by the fuel rods--serves further to moderate the fast neutrons emitted by the nuclear reaction to the slow or thermalized state where these neutrons may continue the nuclear reaction. In this sense, the core bypass region is a particularly important source of nuclear moderator immediate the outside of every fuel bundle. Having explained the nuclear function of the core bypass region, attention can be directed to the fuel rods within the fuel bundle immediately adjacent the channel. This attention will first consider the unique nuclear position of these fuel rods and thereafter the thermal hydraulic limitations of these fuel rods. From a nuclear operational view, the fuel rods adjacent the channel are typically the most reactive fuel locations in the fuel bundle of a boiling water reactor. Because the moderator of the core bypass region is immediately available, these fuel rods--especially in the early life of a fuel bundle--tend to be the most reactive. Consequently, they generate the most power and easily come under so-called "critical power" limits. When a fuel rod approaches critical power limits, the heat generated by the fuel bundle exceeds the ability of the coolant to remove the heat; the excess heat become a threat to the integrity of the cladding of the fuel rod surrounding the nuclear fuel. When this limit is approached, the entire remainder of the fuel bundle is limited in performance so that the critical power limit is not exceeded at any one individual portion of a fuel bundle. From the thermal hydraulic operational view, the peripheral fuel rods must be provided with an adequate flow of coolant to prevent these fuel rods from exceeding the critical power limits. DISCOVERY It should be understood that clearance between the channel inside walls and the chamber wall contact points on the spacers (commonly called bathtubs) exists in present fuel designs. Thus, conventional spacer designs allow movement of the fuel rods as confined by the spacers as a mass with respect to the channel. Such movement can be caused by many forces within the reactor. This movement of the spacer and the fuel rods as a group with respect to the channel enables the outside fuel rods to move in spatial relation towards and away from the channel walls. Typically, overall movement of the fuel rod matrix at the spacer occurs with fuel rods on one bundle side moving away from one channel wall while fuel rods on the opposite side move adjacent an opposite channel wall. When any outside fuel rods close in on and become adjacent to a channel wall, the flow of the moderating coolant is inhibited at these highly reactive outside fuel rods. Critical power losses of as much as 6% can be experienced by these fuel rods adjacent the channel--and especially those fuel rods adjacent the corners of the channel. As a result, the entire fuel bundle must be limited in its performance so that these critical power limits of the peripheral fuel rods are not exceeded. INVENTION SUMMARY OF THE INVENTION In a fuel bundle for a boiling water nuclear reactor, modification of the spacers at the peripheral spacer band is made to maintain a more uniform spacing of the peripheral fuel rods from the channel walls to avoid critical power limitations. The conventional fuel bundle construction include a plurality of side-by-side sealed vertically disposed nuclear fuel rods in a square array supported at a lower tie plate, at least some of the fuel rods fastened to an upper tie plate, and held in designed spaced apart relation as a unitary mass by intermittent vertically placed spacers. A square sectioned channel surrounds the upper tie plate, the lower tie plate, and the fuel rods and spacers therebetween. The square sectioned channel functions to confined fluid flow interior of the fuel bundle between the tie plates and through the fuel rods. At the same time, the channel separates a core bypass region exterior of the channel having high moderator density from the flow path interior of the fuel bundle. The spacers are modified at their peripheral band to prevent the spacer confined group of fuel rods closing on the channel wall due to overall migration of the fuel rods as a group held together by the spacers. According to the invention, two adjacent spacer sides are formed with at least two protrusions--typically in the form of bubble like projections, these protrusions occupying the entire or any fraction of the interval necessary to maintain the fuel rods adjacent the sides at their full optimal spacing from the interior channel walls. Similarly, the remaining two adjacent spacer sides are formed with protrusions--again in the form of bubble like projections, these protrusions occupying a sufficient interval to prevent inadvertent closing of the fuel rods to the channel sides beyond a worst case limit. This worst case limit is chosen to provide the peripheral fuel rods with adequate clearance to avoid critical power limitation and yet leave sufficient clearance between the peripheral band and the channel so that the channel may be conveniently assembled to the fuel bundle. On these two remaining sides of the peripheral spacer band, preferably leaf springs (or some other suitable spring design) are added. These leaf springs are preferably vertical in their longitudinal dimension, fastened to the band at one end, bulged outwardly toward the channel in the middle, and bent inwardly and bearing in sliding relation on the band at the opposite end. In operation, the leaf springs are given sufficient force to bias the fuel rod matrix at the spacer away from the channel wall. Such biasing registers the full dimension protrusions to the channel wall at the opposite sides of the spacer and uniformly spaces the peripheral fuel rods with respect to the channel. Bundle critical power is enhanced. With respect to this invention and the so-called "worst case" dimension, it is to be understood that it is the maximum critical power of the outer fuel rods which is achieved by the centering apparatus and process set forth herein. This has been determined and can be determined by running tests to establish worst case clearances and taking the most conservative results for the outer rods. It will be appreciated that where the interior rods are limiting, the disclosed placement scheme has no value. Further, it will be understood that at assembly of the fuel bundle, the highest power fuel rods can usually be identified, prior to the placement of the fuel bundle into the reactor. Naturally, these fuel rods will be fitted to the adjacent spacer sides occupying the full spacer interval from the channel. The remaining fuel bundle sides having the fuel rods with a lesser critical power will be assigned to the "worst case" limit.
055770908	claims	1. An x-ray apparatus for product irradiation comprising: a chamber and a gas confined within said chamber; means connected to said chamber for heating said gas to create a hot electron plasma and generate x-rays; means disposed proximate to said chamber for magnetically confining said hot electron plasma in an annular configuration; and means for supporting and locating said product proximately to said chamber for receiving x-rays radiating therefrom; and wherein said chamber encompasses an interior opening and said support means is located at least partially within said opening. confining a gas within a chamber; heating said gas to create a hot electron plasma and generate x-rays; magnetically confining said hot electron plasma in an annular configuration; supporting and locating said product proximately to said chamber for receiving x-rays radiated therefrom; and including the steps of forming an interior opening within said chamber and placing the product within said interior opening during irradiation. 2. An apparatus as in claim 1 wherein said background plasma has a density in the range of 10.sup.18 to 10.sup.20 electrons/m.sup.3. 3. An apparatus as in claim 1 wherein said support means includes a conveyor passing through said opening. 4. An apparatus as in claim 1 including a plurality of said chambers and including a means for magnetically confining said plasma associated with each said chamber and wherein said means for heating is connected to each of said plurality of chambers. 5. An apparatus as in claim 4 wherein at least two of said chambers share a portion of one of said means for magnetically confining. 6. An apparatus as in claim 4 wherein said plurality of chambers are arranged coaxially in series. 7. An apparatus as in claim 6 wherein each of said chambers encompasses an interior opening. 8. An apparatus as in claim 7 wherein said support means includes a conveyor passing through said interior opening. 9. An apparatus as in claim 4 wherein said plurality of chambers are arranged in an array surrounding a central open area. 10. An apparatus as in claim 9 wherein said support means is located within said central opening. 11. An apparatus as in claim 1 wherein said gas is a gas from a group including xenon, helium, neon and argon. 12. An apparatus as in claim 1 wherein said means for heating said gas includes a microwave power source. 13. An apparatus as in claim 12 wherein said microwave power source includes means for generating microwave frequencies in the range of 9 GHz to 90 GHz. 14. An apparatus as in claim 1 wherein said means for magnetically confining said plasma includes two electromagnets forming a magnetic mirror with a magnetic mirror field. 15. An apparatus as in claim 14 wherein said magnetic mirror has a mirror ratio of 2. 16. An apparatus as in claim 14 wherein said magnetic field has a magnitude in the range of 3.2 to 32 kgauss. 17. An apparatus as in claim 1 wherein said plasma is heated to a temperature of about 2 MeV. 18. An apparatus as in claim 1 wherein said gas is a noble gas. 19. An apparatus as in claim 1 wherein said chamber includes sidewalls made of a high Z material to enhance x-ray generation. 20. A method for product irradiation comprising: 21. A method as in claim 20 wherein said gas is a noble gas. 22. A method as in claim 20 wherein said gas is a gas from a group including xenon, helium, neon and argon. 23. A method as in claim 20 wherein said step of supporting and locating includes the step of conveying said product through said interior opening. 24. A method as in claim 20 including the step of arranging a plurality of said chambers coaxially in series. 25. A method as in claim 24 including the step of forming an interior opening within each of said chambers. 26. A method as in claim 25 wherein said step of supporting and locating includes the step of conveying said product through each chamber interior opening. 27. A method as in claim 20 including the step of arranging a plurality of said chambers in an array surrounding a central open area and said supporting and locating step includes locating said product in said central open area. 28. A method as in claim 20 wherein said heating step includes using a microwave power source. 29. A method as in claim 28 further including operating said microwave power source in the frequency range of 9 GHz to 90 GHz. 30. A method as in claim 20 wherein said magnetically confining step includes forming a magnetic mirror and a magnetic mirror field using two electromagnets. 31. A method as in claim 30 including forming said magnetic mirror field with a magnitude in the range of 3.2 to 32 kgauss. 32. A method as in claim 20 wherein said heating step includes heating said plasma to a temperature of about 2 MeV.
052763358	abstract	A cask for storing and transporting highly radioactive materials includes an inner shell and a number of layers of depleted uranium wire wound on the inner shell to create a radioactive shield against emanation of radioactivity from the material stored within the inner shell.
041939530	description	Examples of the process of the invention are set forth below. The hydrosols having high concentration of heavy metal are produced as follows. ThO.sub.2 hydrosols are quite simply produced by addition of gaseous or dissolved ammonia to solutions of Th(NO.sub.3).sub.4. The precipitate thus produced can easily be collodially suspended by stirring at increased temperature, preferably at 95.+-.10.degree. C. After introduction of 80-90% of the aqua ammonia quantity which is necessary for a complete precipitation, an aquasol is obtained in which the precipitation is almost reached. The sols are stabilized by hydrogen ions and have a pH value of about 3. For the production of the mixed oxide grains of (Th,U).sub.2, up to a Th:U ratio of 3:1, solutions can be used as starting materials for the sol production that contain UO.sub.2 (NO.sub.3).sub.2 in addition to Th(NO.sub.3).sub.4. EXAMPLE 1 2.5 moles of Th(NO.sub.3).sub.4.5H.sub.2 0 were dissolved in 0.5 liter of H.sub.2 O and the solution was heated to 80.degree. C. Beginning at this temperature, NH.sub.3 gas was introduced through the shaft of the stirrer. The temperature then rose as a result approximately to the boiling point of the solution of about 110.degree. C. After an hour 85% by weight of the amount of ammonia gas necessary for the complete precipitation reaction had been introduced. In the course of an additional hour, an additional 5% amount of ammonia by weight was gradually introduced. After cooling the hydrosol was filled out with H.sub.2 O to the volume of 1 liter. The hydrosol thus prepared was cloudy-white and at 20.degree. C. had a viscosity of .eta.=8 cP and a pH value of 3.5. This hydrosol was dripped in a drip casting column having at the bottom a precipitation bath containing aqua ammonia and thereabove an ammonia-containing gas phase. The hydrosol was injected in drop form at 40.degree. C. horizontally into the gas phase at a velocity allowing the drops to fall through the gas phase by gravity until they fell into the precipitation bath. The height through which the drops fell in the drip casting column was 5 cm. The height was so chosen that the prehardening of the drops in the gas phase is just sufficient to prevent permanent deformation of the drops upon hitting the surface of the precipitation bath. The hydrosol was drip-cast at a drop frequency of 400 HZ with a drop diameter of 1.24 mm. The precipitation bath contained 5 moles per liter of ammonium nitrate and 1% by weight of ammonium hydroxide. The gel spheres produced in this manner were washed free of ammonium nitrate with water that contained 0.01% of surfactant which is available under the common commercial designation "Span 80" and was then dried at 250.degree. C. at an atmosphere containing water vapor. The cores of ThO.sub.2 thereafter sintered had a diameter of 500 .mu.m with good spherical shape, and a density of 99.8% of that theoretically possible. The yield was 99.9%. EXAMPLE 2 2.4 moles of Th(NO.sub.3).sub.4.5H.sub.2 O were dissolved together with 0.6 moles of UO.sub.2 (NO.sub.3).sub.2.6H.sub.2 O in 0.5 liter of water that had been heated to 80.degree. C. and--as described in Example 1--was converted to a hydrosol of 1 liter. The prepared hydrosol that had an intense dark red color, had a viscosity of 6.5 cP. The pH value measured was 3.2. The hydrosol--warmed to a temperature of 30.degree. C.--was drip-cast in the same manner as in Example 1. The washing and drying of the gel spheres was also carried out in the same manner as in Example 1. The high temperature treatment, however, was carried out so as to reduce the hexavalent uranium to tetravalent uranium, in a reducing atmosphere of argon with 4% by weight of hydrogen. The results were comparable to those of Example 1. EXAMPLE 3 1.5 moles of Th(NO.sub.3).sub.4.5H.sub.2 O were dissolved in hot water of a temperature of 80.degree. C. and--as described in Examples 1 and 2--converted into a ThO.sub.2 hydrosol of a volume of one liter. The hydrosol had a pH value of 4.0 and a viscosity of 10 cP. The hydrosol was drip-cast at a temperature of 60.degree. C. The remaining treatment corresponded to that given in Example 1. The sintered ThO.sub.2 granules had a diameter of 400 .mu.m. The performance of the process with an ammonia-hydroxide concentration in the precipitation bath in the range between 3 and 5 moles per liter brought about comparable results. In addition to use for the production of fuel and breeder particles of thorium oxide or granules containing thorium-uranium mixed oxides, it is also possible to apply the process to the manufacture of thorium-plutonium mixed oxide granules. Although the invention has been illustrated by means of particular examples, it is evident that variations and modifications are possible within the inventive concept.
	description	The present application is a divisional application of copending application Ser. No. 11/197,273, filed Aug. 4, 2005, the teachings of which are incorporated herein by reference. 1. Field of the Invention The present invention concerns a method for operating an x-ray device, in particular a mammography x-ray apparatus, of the type that emits an x-ray beam that exhibits a movement in the manner of a scan of a subject. 2. Description of the Prior Art In x-ray imaging, the imaging properties are negatively influenced (such as blurring) by the scatter radiation of the x-ray beam generated by an anode, for example a rotary anode. To prevent such scatter radiation, in addition to scattered-ray grids scan methods are used in which a fan-shaped x-ray beam is excised from the totality of emitted, x-rays by a slit-shaped diaphragm, and the diaphragm and the x-ray beam are moved in a grid-like manner over the subject to be imaged. Furthermore, to prevent scatter radiation it is known to provide a further slit diaphragm between the subject and the radiation detector that converts the x-ray radiation into an image signal. It is also known to divide the detector into row-like regions and to only map the respective region passed over by the x-ray beam. It cannot be prevented, however, that regions of the x-ray beam that produce a different image resolution are gated by means of the movement of the diaphragm, such that the generated image exhibits differing image definitions. An x-ray device for implementing a scanning method is known from U.S. Pat. No. 4,928,297, in which an x-ray tube, a slit-shaped diaphragm and a row-like detector are arranged in a line and are fastened together on a shaft. This unit is mounted such that it can rotate around an axis intersecting the line, above the x-ray tube. The necessary synchronization of the mechanical movements is thereby made particularly simple. It is an object of the present invention to provide a method for operating an x-ray device with which an improvement in the quality of x-ray images, in particular with regard to obtaining a sharp image over the entire region, can be achieved in a low-cost manner. The above object is achieved in accordance with the present invention by a method for operating an x-ray device having an x-ray tube that emits an x-ray beam from a focal spot of a rotary anode that is rotatable around a rotational axis, the emitted x-ray beam having a region that is either a region of highest image resolution or a region of highest image definition. A slit-shaped diaphragm is disposed in the path of the emitted x-ray beam, and gates a fan-shaped x-ray beam therefrom. The fan-shaped x-ray beam is caused to move through an examination region substantially in the direction of the rotational axis of the rotary anode by tilting the x-ray tube relative to the focal spot. The x-ray tube is tilted relative to the focal spot so that the fan-shaped x-ray beam is always gated from the aforementioned region of highest image resolution or region of highest image definition during the movement through the examination region. The x-ray device is particularly suited for use in a mammography x-ray apparatus. By tilting the x-ray tube in accordance with the invention with a mounting arrangement for the x-ray tube, the emitted x-ray beam is moved over the examination region so that the fan-shaped beam always is gated from the region of highest image resolution or image sharpness of the emitted x-ray beam (which is on the side of the x-ray beam facing the rotary anode), and thus overall a uniform and high image definition or high image resolution is ensured over the examination region in a simple manner. The image sharpness can be still further improved in an embodiment wherein, in combination with the tilting of the x-ray tube, the slit-shaped diaphragm can be moved over the examination region substantially in the direction of the rotational axis of the rotary anode and substantially synchronously with the movement of the fan-shaped x-ray beam. This ensures that the region of highest image resolution of the x-ray beam is always gated by the slit-shaped diaphragm. The use of the inventive x-ray device can be expanded in an advantageous manner by the opening of the slit-shaped diaphragm being adjusted to cover the entire examination region, i.e. in the whole-field range. The x-ray device is thereby made usable for all types of whole-field examinations. The whole-field examination can be still further improved by the inventive x-ray device in an embodiment wherein the slit-shaped diaphragm is adjusted to cover the entire examination region and the x-ray beam is adjusted so its region of highest image resolution stays within this slit solely by the tilting of the x-ray tube in a defined range of the examination region. The tilting of the x-ray tube, which leads to an effective reduction of the anode inclination angle of the rotary anode, also leads to a reduction of the image definition differences over the examination region for a whole-field examination, and thus achieves a sharper image overall. By the tilting of the x-ray tube, the region with the highest image definition can additionally be adjusted to match the subject to be examined, such that a complete utilization of this region is possible. According to a further embodiment of the invention, the focal spot can be enlarged in the radial direction of the rotary anode. The x-ray power can thereby be increased without loss due to the higher focal spot area, since the tube is inventively tilted to adjust the image definition. The advantage of an increase of the x-ray power is a reduction of the scan time. The shortening of the examination time thereby achieved is desirable for a patient to be examined with the x-ray device since the patient must remain still during the x-ray exposure, which (primarily in mammography) can be painful for the patient. For variable adjustment (and therewith selectable enlargement as needed) of the focal spot, at least two emitters (in particular of different specifications for generation of a focal spot of corresponding dimensions) are provided in an inventive x-ray device with a cathode for generation of an electron beam. The cathode has at least one emitter with at least one intermediate tap for separate activation of sub-regions of the emitter. The dimensions of the focal spot thus can be increased by using both sub-regions of the emitter. A number of emitters with a number of intermediate taps can also be provided in order to allow further adjustment possibilities of the dimensions of the focal spot. FIG. 1 shows a generally known x-ray device 30 for imaging a subject 6. The device 30 has a slit-shaped diaphragm 4 for generation of a fan-shaped x-ray beam 5 that can be gated from the overall emitted x-ray beam and moved over an examination region 8 in the manner of a scan. The x-ray device 30 has an x-ray tube 1 with a rotary anode 2 that can be rotated around a rotational axis 3, as well as a 2D detector 10 for acquiring the entire examination region of the subject 6. The lengthwise extent of the fan-shaped x-ray beam 5 is essentially parallel to the rotational axis 3 of the rotary anode 2; the scan direction over the examination region is essentially perpendicular to the plane of the fan-shaped x-ray beam 5. The scanning ensues by movement of the opening of the slit-shaped diaphragm 4 in the arrow direction s1. FIG. 2 through FIG. 7 respectively show an inventive x-ray device 31 for scanning a subject 6 on an examination region 8 in various tilt positions of the x-ray tube 1. The x-ray tube 1 emits a total emitted x-ray beam 37 (see FIG. 8). A fan-shaped x-ray beam 5 is gated from the total emitted beam 37 by the slit-shaped diaphragm 4. The total emitted x-ray beam 37 has a region of highest image definition or resolution. The x-ray tube 1 is tiltably mounted at a mounting unit 38 that tilts the x-ray tube 1 to move the fan beam 5 over the examination region 8 in the direction essentially along the rotational axis 3 of the rotary anode 2 and perpendicular to the plane of the fan-shaped x-ray beam 5, as indicated by the arrow s2 on the detector 10 in FIGS. 2, 4 and 6. FIGS. 2 and 3 show a first tilt position of the x-ray tube 2. The tilting by the mounting unit 38 is designed so that the slit-shaped diaphragm 4 always gates in the aforementioned region of the highest image definition of the rotary anode 2 to form the fan beam 5, with a corresponding anode inclination angle that faces the rotary anode 2. The fan-shaped x-ray beam 5 is moved over the examination region 8 in the manner of a scanner by the tilting of the x-ray tube 1 on a tilt axis 26 proceeding through the focal spot 7, parallel to the surface of the examination region 8 and perpendicular to a first axis 16. The diaphragm 4 can be moved as well, synchronized, such that the same x-ray beam 5 remains gated. FIGS. 4 and 5 show a second tilt position of the x-ray tube 1 and FIGS. 6 and 7 show a third tilt position of the x-ray tube 1. FIG. 8 shows an inventive x-ray device 31 with a slit-shaped diaphragm 4 fashioned with an opening covering the entire examination region. The diaphragm 4 has two diaphragm plates 4.1 and 4.2 delimiting the slit opening that can be moved toward and away from one another and/or relative to one another to displace the slit opening. The inventive x-ray device can also be used in a whole-field mode in a simple manner. This is advantageous since important information can be acquired by comparisons between images of the same subject with the same x-ray device with scatter radiation suppression and without scatter radiation suppression. Moreover, the whole-field mode affords the possibility of using imaging methods that require large fields of view. In the whole-field mode, the inventive tilting of the x-ray tube 1 with the diaphragm 4 moved out of the x-ray beam 5 enables adjustment of the region of highest image resolution of the x-ray beam 5 to each part of the examination region, controlled by the tilting for the particular acquisition. Moreover, it is possible to move only a single diaphragm plate 4.1 or 4.2 out of the x-ray beam 5 and to use the other diaphragm plate 4.1 or 4.2 to mask partial regions of the x-ray beam 5. The diaphragm plates 4.1 and 4.2 also can be individually or mutually connected to form a unit with the x-ray tube 1 so that they can be tilted as well given a tilting of the x-ray tube 1. FIG. 9 shows a portion of an inventive x-ray device 31 with a rotary anode 2 and a cathode 9 for generation of an electron beam 11 that, through its impact area on the rotary anode 2, determines the size of the focal spot 7. The cathode 9—as shown in FIG. 10—has at least two emitters 12, 13 of different specifications, for generation of focal spots 7 of different dimensions. A selection between at least two differently-sized focal spots is thereby possible. The x-ray power can be increased and thus the scan duration can be reduced by selection of a larger focal spot relative to a smaller one; at the same time losses of image definition can be compensated by the inventive tilting. An alternative cathode 9 is shown in FIG. 11. According to one embodiment of the invention, the cathode 9 has at least one emitter 14 with at least one intermediate tap 15 for separate activation of partial regions of the emitter 14, allowing selection between at least two focal spots of different sizes. Instead of one partial region, the entire emitter 14 can be used for generation of the electron beam and therewith the focal spot 7. An increase of the x-ray power and ultimately a shortening of the scan time thereby result. A further embodiment of the inventive x-ray device 32 is shown in FIGS. 12 through 13. In addition to the inventive tilting, the x-ray tube 1 also can be rotated in around a first axis 16, proceeding through the focal spot 7 and perpendicular to the examination region 8. FIG. 12 shows the x-ray tube 1 in a first position, for example before rotation around the first axis 16; FIG. 13 shows the same x-ray tube 1 after such a rotation by 90°. A repositioning of the subject 6 is avoided by the rotation. The examination is thereby made easier and less uncomfortable for a patient. FIG. 14 shows an alternative method for reduction of the scatter radiation in an inventive x-ray device 33. A further movable slit-shaped diaphragm 24 is provided that is arranged proximate to the detector. The detector-proximate diaphragm 24 can be moved over the examination region 8 in synchronization with the x-ray beam 5 such that the scatter radiation is filtered out. The detector-proximate diaphragm 24 alternatively can be fashioned as a scattered-ray grid and be composed of tiltable lamellae diagnosed parallel to the movement direction of the x-ray beam 5. With the use of the detector-proximate diaphragm 24, rotation around the first axis 16 (shown in FIGS. 12 and 13) enables the opening (aperture) of the detector-proximate diaphragm 24 to be moved up to a point directly on the edge of the examination region 8; this was conventionally prevented (for example in mammography) by the sternum of the patient. In general, in the scanning mode it is also necessary to rotate the diaphragm 24 around the first axis 16. The detector 10 can also be moved at the same time as well. A detector 10 is appropriately fashioned as a detector surface covering the entire examination region 8. For a further reduction of scatter radiation, in an inventive x-ray device 34 with a detector 19 for conversion of x-ray radiation into an image signal, the detector 19 is designed as a detector row 19 (as is shown, among other things, in FIGS. 15 and 16) covering only a portion of the examination region, extending transverse to the movement direction of the x-ray beam 5 and movable over the examination region 8. In two views, FIG. 15 and FIG. 16 show a further rotation displacement possibility of the x-ray tube 1. The tiltable x-ray tube 1 can additionally be rotated around a second axis 17 that lies in the plane of the fan-shaped x-ray beam 5, perpendicular to the rotational axis 3 of the rotary anode 2 and outside of the focal spot 7 at the side thereof facing away from the examination region 8. By this rotation around the second axis 17, the fan-shaped x-ray beam 5 can be moved so that the rotational axis 3 of the rotary anode 2 essentially lies in the plane perpendicular to the fan plane of the fan-shaped x-ray beam 5. The focal spot 7, the slit (generated by the slit-shaped diaphragm 4) with its center point and the detector 19 can be appropriately arranged in a line 18 and be moved along this line 18. If, for example, the x-ray tube 1 and the slit-shaped diaphragm 4 are moved together toward the examination region 8, this has the advantage that no distortions of the image can occur. The x-ray power per area can be increased, and therewith the scan time can be reduced, by the approach of the x-ray tube toward the examination region. By rotation of the x-ray tube around the second axis 17 and simultaneous arrangement of the x-ray tube 1, the slit-shaped diaphragm 4 and the detector row 19 in a line 18, the slit-shaped diaphragm 4 and the detector row 19 can be rotated around the second axis 17 in synchronization with the x-ray tube 1, and the examination region 8 can likewise be scanned. FIG. 17 shows an embodiment with a detector 20 that is composed of a series of parallel detector rows (for example 21-23) arranged perpendicular to the movement direction (indicated by the arrow s4) of the x-ray beam 5. To prevent scatter radiation, according to one embodiment of the invention the detector rows can respectively be activated individually dependent on being passed over by the x-ray beam 5, as is shown in FIG. 18 wherein the detector row 21 is passed over by the x-ray beam 5. In realization that the scatter radiation can also provide important image information (for example for differential diagnostics) dependent on the subject to be imaged, in an inventive x-ray device 35 detector rows 22; 23 can be activated dependent on the passage of the x-ray beam 5 over adjacent detector row 21 for measurement of scatter radiation. According to one embodiment of the invention, a slit displacement of the slit-shaped diaphragm 4 occurs dependent (in control terms) on changes of the ratio of the scatter radiation to the useable radiation of the ray beam, by widening the opening of the slit-shaped diaphragm 4 upon reduction of the ratio and narrowing the opening of the slit-shaped diaphragm 4 upon an increase of the ratio. Although scatter radiation is low given a very narrow slit, the duration of the scan is long, which can mean an unwanted exposure for the patient. As also shown in FIG. 18, the x-ray device in accordance with the invention is particularly suited for mammography. FIG. 18 shows a mammography apparatus having a support plate 39 on which a female breast 41 is compressed by a compression plate 40. The radiation detector 20 is disposed in the support plate 39. The support plate 39 and the compression plate 40 as is known, are composed of suitably x-ray transparent material. According to a further embodiment, in an inventive x-ray device with the dose rate of the x-ray tube dependent on the x-ray beam, a controller for the dose rate of the x-ray tube is provided that controls the dose rate dependent on the image contrast and the radiation exposure of a patient, by increasing of the x-ray dose given low image contrast and reducing the x-ray dose given high radiation exposure of the patient. By the adjustment of the dose in a region passed over at the beginning of the scan, unnecessary radiation exposure of the patient is prevented and, at the same time, the contrast of the x-ray images is optimized for the remaining region. FIG. 19 shows a further embodiment of the inventive x-ray device 36. The radial extent of the focal spot 7 is determined by the bisecting lines 27 of the aperture angle α of the x-ray beam 5. The image definition of the x-ray image is thereby additionally increased since this is highest in the plane of the rotary anode at the elongation of the focal spot and is less given removal of this line. in accordance with the principles of the present invention the image resolution or image definition is improved by fan-shaped ray beam being moved over the examination region essentially in the direction of the rotation axis of the rotary anode and the x-ray tube can be tilted on the focal spot such that the fan-shaped x-ray beam lies in the region of highest image resolution given movement over the examination region. Although modifications and changes may be suggested by those skilled in the art, it is the intention of the inventors to embody within the patent warranted hereon all changes and modifications as reasonably and properly come within the scope of the contribution to the art.
	abstract	Method and apparatus for heating and/or compressing plasmas to thermonuclear temperatures and densities are provided. In one aspect, at least one of at least two plasmoids separated by a distance is accelerated towards the other. The plasmoids interact, for instance to form a resultant plasmoid, to convert a kinetic energy into a thermal energy. The resultant plasmoid is confined in a high energy density state using a magnetic field. One or more plasmoids may be compressed. Energy may be recovered, for example via a blanket and/or directly via one or more coils that create a magnetic field and/or circuits that control the coils.
	abstract	Illustrative embodiments provide for the operation and simulation of the operation of fission reactors. Illustrative embodiments and aspects include, without limitation, nuclear fission reactors and reactor modules, including modular nuclear fission reactors and reactor modules, nuclear fission deflagration wave reactors and reactor modules, modular nuclear fission deflagration wave reactors and modules, methods of operating nuclear reactors and modules including the aforementioned, methods of simulating operating nuclear reactors and modules including the aforementioned, and the like.
	description	A WJP method (preventive maintenance method) for a vertical weld portion (or line) of a core shroud (hereinafter referred to as xe2x80x9cshroudxe2x80x9d) in a boiling water reactor (BWR) according to the first embodiment of the present invention is explained by FIG. 1. In this embodiment, an object of the WJP is the vertical weld portion on an outer surface of the shroud. The vertical weld portion is one of narrow space portions in a RPV (reactor pressure vessel). FIG. 1A shows a schematic longitudinal sectional view of the RPV in a state that a top head of the RPV, a steam drier and a shroud head are removed from the RPV. In this state, the RPV 13 is filled with core water 22 and riser pipes 24, jet pumps 25, core cooling pipes 27, etc. are mounted in an annulus portion (a narrow space portion) between the shroud 23 and the RPV 13. In some cases, the vertical weld portion 17 of the shroud 23 is located near the riser pipe 24, and a distance (a spatial width) between the vertical weld portion 17 and the riser pipe 24 is as narrow as about a few tens (20 to 30) mm. In a case that the spatial width is narrow like this, it is impossible to direct a nozzle 4 to the vertical weld portion 17 and to discharge a water jet (hereinafter referred to as xe2x80x9cjetxe2x80x9d) 3 from the nozzle 4. FIG. 1A shows also an ICM housing mounted in a bottom head 26 of the RPV 13. FIG. 1B is a schematic configuration view which shows a state that the WJP method of the present invention is applied to the vertical weld portion on the outer surface of the shroud. In FIG. 1B, the riser pipe 24 is not shown for simplicity. As shown in FIG. 1B, the nozzle 4 is inserted substantially in parallel to the outer surface of the shroud 23 by moving a lifting means 6 using, for example, a fuel exchanger assisting hoist (not shown). Pressurized water flows through a hole in the nozzle 4 and is discharged downward from an opening of the nozzle 4 as a jet 3. When the jet 3 is discharged from the opening, cavitation bubbles 2a are generated. This jet 3 containing cavitation bubbles 2a collides with (or impinges on) a plane surface (hereinafter referred to as xe2x80x9ca collision surfacexe2x80x9d) of a baffle body 5a provided near the vertical weld portion 17. The jet 3 changes direction and velocity of its flow by the collision with the collision surface of the baffle body 5a, and collides with the vertical weld portion 17 as a collision jet 9a. That is, the baffle body 5a is a deflector of the jet 3. Although it is omitted in FIG. 1B, practically, a relative position between the nozzle 4 and the collision surface of the baffle body 5a is maintained by a support. A distance between an end of the nozzle 4 and the collision surface 50 of the baffle body 5a is defined as a collision distance L as shown in FIG. 1C. Strictly, the collision distance L is a distance in a central axis 3a passing through the opening of the nozzle 4. In this embodiment, the collision distance L is set at most 100 times (preferably at most 50 times) as large as a hole diameter of the nozzle 4. This hole diameter means a substantial diameter of the hole in the nozzle 4. By arranging the nozzle 4 and the baffle body Sa so as to meet the above condition, the jet 3 collides with the collision surface so before fine cavitation bubbles contained in the jet 3 become large. Therefore, since the amount (a ratio) of the cavitation bubbles collapsed by the collision with the collision surface 50 is reduced and the jet 3 collides with the collision surface 50 before its velocity becomes low, the collision jet 9a including a strong vortex flow and a strong separation flow is generated. Accordingly, the fine cavitation bubbles, which are not collapsed by the collision with the collision surface 50, grow in the collision jet 9a and collapse at the vertical weld portion 17 with high collapse pressures, thereby a tensile residual stress of the vertical weld portion 17 can be reduced effectively. If the collision distance L is set more than 100 times as large as the hole diameter of the nozzle 4, the amount (the ratio) of the cavitation bubbles collapsed by the collision with the collision surface 50 becomes large and the velocity of the jet 3 becomes low. Therefore, the amount (the ratio) of the cavitation bubbles contained in the collision jet 9a is reduced and an improvement effect of the residual stress decreases. As shown in FIG. 1C, an angle formed the central axis 3a passing through the opening of the nozzle 4 and the collision surface 50 is defined as a collision angle. Strictly, the collision angle is a lower (smaller) angle of two angles formed the central axis 3a and the collision surface 50 on a plane 51 including both the central axis 3a and a perpendicular line 50a of the collision surface 50, the perpendicular line 50a passing through an intersection point where the central axis 3a crosses the collision surface 50. The collision angle is an acute angle except a case that the central axis 3a crosses perpendicularly the collision surface 50. The collision angle is needed to be at least 10. When the jet 3 collides with the collision surface 50, not only the collision jet 9a flowing toward the vertical weld portion 17 but also, for example, a collision jet 9b flowing opposite to the vertical weld portion 17 is generated. If the collision angle is set about 10, since the collision surface has a steep slope (incline) to the vertical weld portion 17, a rate of the collision jet 9a can be higher and a rate of the collision jet 9b can be lower in comparison with a case of less than 10. In this case, however, the vortex flow and the separation flow in the collision jet 9a are not so strong because the water-hammering effect on the collision surface 50 is still weak. Therefore, a long period of time for discharging the jet 3 is needed to attain a desired effect of improving the residual stress. In this embodiment, the collision angle is set in a range of 40 to 90 (preferably in a range of 60 to 90). In this case, since the water-hammering effect on the collision surface 50 becomes strong, the strong vortex flow and the strong separation flow can be generated in the collision jet 9a. Accordingly, it is possible to impinge the collision jet 9a containing the cavitation bubbles with the high collapse pressures on the vertical weld portion 17, and also attain the desired effect of improving the residual stress more effectively. According to this embodiment, it is easy to indirectly impinge the jet 3 on the vertical weld portion 17 without directing the nozzle 4 to the vertical weld portion 17. When the jet 3 collides with the collision surface 50, part of cavitation bubbles 2a contained in the jet 3 collapse due to an increase of a fluid pressure caused by the water-hammering effect. But the remaining cavitation bubbles, which do not collapse on the collision surface 50, grow to the cavitation bubbles with the high collapse pressures in the collision jet 9a including the strong vortex flow and the strong separation flow. In the collision jet 9a, in addition to the above mentioned growth of the remaining cavitation bubbles, new cavitation bubbles are also generated and then grow. As a result, the collapse pressure of the collision jet 9a on the vertical weld portion 17 becomes higher, and it is possible to attain the effect of improving significantly the residual stress of the vertical weld portion 17. FIG. 1D shows another example of the baffle body which is used for changing the direction of the flow of the jet 3 in FIG. 1B. This baffle body has a curved surface 5d as the collision surface and jet guides 5dxe2x80x2 which are provided at both sides of the curved surface 5d. In a case of using this baffle body, the strong vortex flow and the strong separation flow are generated in the collision jet 9a, and the collision jet 9a containing the cavitation bubbles with the high collapse pressures can collide with (impinge on) the vertical weld portion 17. Further, it is possible to reduce effectively the rate (amount) of collision jet except the collision jet 9a flowing toward the weld portion 17. One example of a nozzle head, which can discharge a collision jet to almost one direction, according to the present invention is explained by FIG. 2. FIG. 2 shows a schematic configuration view of a nozzle head 15a which is a one-sided discharging type and has a flow baffle 5 with an opening at one side. Hereinafter, this flow baffle is referred to as xe2x80x9ca one-sided opening type flow bafflexe2x80x9d. This flow baffle 5 is formed into a cylindrical shape and has a square-shaped opening 5b which is formed by cutting out a circumferential part near one end portion of the cylinder. A baffle body 5a is removably engaged with the one end portion of the flow baffle 5 at a position adjacent to the opening 5b in such a manner that a collision jet 9a passing through the opening 5b collides with a surface to be treated. The nozzle head 15a is constructed by engaging removably a nozzle 4 with the other end portion of the flow baffle 5. Since the baffle body 5a is removably engaged with the flow baffle 5, when the baffle body 5a is worn, it can be easily replaced with a new one. Therefore, reliability of execution of WJP can be maintained. In this nozzle head 15a, a collision distance and a collision angle are set in the above-mentioned range. In FIG. 2, the jet 3 collides with the collision surface of the baffle body 5a to change its flow direction, and the collision jet 9a directly collides with the surface to be treated. A collision jet 9b flowing toward direction in which the opening 5b is not provided, changes its flow direction toward the opening 5b by making a second collision with an inner wall of the flow baffle 5, and are discharged from the opening 5b so as to make a third collision with the surface to be treated. In this case, cavitation bubbles in the collision jet grow more largely by this second collision, and the collision jet can restrictively collide with the surface to be treated. Further, by making fine irregularities on the collision surface of the baffle body 5a, the cavitation bubbles grow largely by the collision with the collision surface having the fine irregularities. This growth of the cavitation bubbles can make a strong peening effect (a strong effect of improving the residual stress) in cooperation with the above mentioned repeated collision. In FIG. 2, it is possible to replace the cylindrical flow baffle with a square pipe flow baffle. It is also possible to replace the plane collision surface with a curved surface as shown in FIG. 1C. FIG. 3 shows one example of an improvement effect of the residual stress by using the one-sided discharging type nozzle head 15a shown in FIG. 2. The nozzle having an outer diameter of 30 mm and a hole diameter of 2 mm is used. The baffle body 5a is arranged so as to make the collision distance of 80 mm and the collision angle of 70. The one-sided opening type flow baffle 5 has the opening 5b in a half circumferential part. FIG. 3 shows a measurement result of the residual stress on a surface of a strip-shaped (plate-shaped) test piece after executing the WJP to the test piece using this nozzle head 15a. The WJP is executed in a condition that the nozzle head is moving to a longitudinal direction (Y-direction) by keeping a distance between the nozzle head and the surface of the test piece about 5 mm. In FIG. 3, a vertical axis is a relative measurement value of the residual stress, and a horizontal axis is a distance from a center line (Y-axis) of the test piece in a width direction (X-direction). A positive residual stress is a tensile residual stress, and a negative residual stress is a compressive residual stress. The surface of the test piece is subjected to surface grinding so as to have a tensile residual stress of about 400 MPa as an initial residual stress. As shown in FIG. 3, the initial tensile residual stress is improved to the compressive residual stress in a range in which the collision jet collides with the surface of the test piece. The first embodiment, in which the WJP method according to the present invention is applied to the vertical weld portion on the outer surface of the shroud in a BWR plant after at least the first operation cycle, is explained in more detail using FIG. 4 and FIG. 5. A WJP apparatus having the one-sided discharging type nozzle head 15a with the cylindrical flow baffle 5 is used. The collision distance and the collision angle are set in the above-mentioned range, respectively. FIG. 4 is a schematic longitudinal sectional view, which shows a state of the WJP execution, of a surrounding area near the RPV. FIG. 4 also shows the third embodiment in which the WJP method according to the present invention is applied to a horizontal weld portion of an ICM housing. FIG. 5 is a schematic flow chart which shows execution steps of the WJP in the first embodiment. Each step is explained below according to the flow chart of FIG. 5. (1) Disconnection: A top head of the RPV, a steam drier and a shroud head are removed from the RPV. In this state, the RPV 13 and a reactor well are filled with core water 22. (2) Detection of weld line: A weld line detector (not shown) is lowered and set near an outer surface of the shroud using, for example, a fuel exchanger assisting hoist (hereinafter referred to as xe2x80x9cassisting hoistxe2x80x9d) 21. A vertical weld portion (line) is detected by the weld line detector. (3) Confirmation of access route: While a monitor camera 30 is lowered using, for example, the assisting hoist 21, an access route to the weld line 17, presence or absence of an obstacle to set a WJP main body 29, and the weld line 17 are confirmed by means of a monitor video 31. A spatial distance between a riser pipe 24 and the shroud 23 is measured to confirm that a nozzle head can be inserted into the space. (4) Setting of WJP apparatus: A control panel 20 and a booster pump 18 are disposed on an operation floor. The booster pump 18 is connected to a source water tank (not shown) by means of a water supply hose 19. The booster pump 18 is connected to the WJP main body 29 by means of a high-pressure hose 7. Wiring between these devices is laid out, and these devices are adjusted. (5) Setting of WJP main body: This step has next steps of a) to e). a) Lowering: The WJP main body 29 is lowered by the assisting hoist 21 to a specific height in a space between the shroud 23 and the RPV 13. It is confirmed by the monitor camera 30 and the monitor video 31 that the WJP main body 29 is located in a suitable height. b) Fixing: Upper and lower portions of the WJP main body 29 are fixed on a shroud""s side and a RPV""s side by a support 29a and a support 29b. c) Extending nozzle arm: A nozzle head 15a fixed at a top end of a nozzle arm 33 is inserted between the shroud 23 and the riser pipe 24 by extending forwardly the nozzle arm 33. d) Confirmation of position: A distance between the weld line 17 and the nozzle head 15a and discharging direction are confirmed by the monitor camera 30 and the monitor video 31. e) Trial discharge of jet: A trial discharge of a collision jet 9 is performed to confirm that the collision jet 9 collides with a desired position by the monitor camera 30 and the monitor video 31. It is the last step for setting of the WJP main body 29. (6) Execution of WJP: This step has next steps of a) to c). a) Setting of execution conditions: A discharging pressure and a flow rate of the jet, and a moving speed and a moving range of the nozzle head 15a are set. b) Discharge of jet: The collision jet 9 is discharged and the nozzle head 15a is moved in a vertical direction along the weld line 17 to execute the WJP. This execution state of the WJP is confirmed by the monitor camera 30 and the monitor video 31. In this state, the schematic longitudinal sectional view of the surrounding area near the RPV is shown in FIG. 4A, and a top view of a surrounding area near the WJP main body 29 is shown in FIG. 4B. c) Confirmation of execution of WJP: A state of a surrounding area near the weld line 17 after the execution of the WJP is confirmed by the monitor camera 30 and the monitor video 31 to terminate the execution of the WJP. (7) Withdrawal of WJP main body: This step has next steps of a) to d). a) Folding of nozzle arm: The nozzle arm 33 is folded to be contained in the WJP main body 29. b) Release of main body: The WJP main body 29 fixed between the shroud 23 and the RPV 13 is released. c) Confirmation of preparation for lifting: A termination of preparation for lifting the WJP main body 29 is confirmed by the monitor camera 30 and the monitor video 31. d) Lifting of main body: The WJP main body 29 is lifted by the assisting hoist 21. (8) Withdrawal of WJP apparatus: The connection between the booster pump 18 and the source water tank by the water supply hose 19 and the connection between the booster pomp 18 and the WJP main body 29 by the high pressure hose 7 are released, and the wiring between these devices is removed. The apparatuses such as the WJP main body 29, the control panel 20, the booster pump 18, the high pressure hose 7 and the water supply hose 19 are withdrawn. (9) Withdrawal of monitor camera: The monitor camera 30 is withdrawn. (10) Withdrawal of weld line detector: The weld line detector is withdrawn to terminate the execution of the WJP. (11) Synchronization: The shroud head, the steam drier, and the top head of the RPV are lowered and assembled to be restored. By executing (applying) the WJP with the above steps to the vertical weld portion on the outer surface of the shroud in the RPV filled with the core water, it is possible to collapse cavitation bubbles with high collapse pressures on a surface of the vertical weld portion. Accordingly, the residual stress on the surface of the vertical weld portion can be improved and a damage such as the SCC can be prevented. When the above WJP method is executed during an outage of the BWR plant, since the top head of the RPV, the steam drier and the shroud head are already removed, the execution of the WJP is started from the step (2) and terminated at the step (9). The one-sided discharging type nozzle head 15a can be applied to axial weld lines on both inner and outer surfaces of a weld pipe. Of course, it can be applied to a weld pipe with no weld line. One example of a four-sided discharging type nozzle head according to the present invention is explained by FIG. 6. FIG. 6A shows a schematic configuration view of this nozzle head, and FIG. 6B shows an Axe2x80x94A cross sectional view of FIG. 6A. This nozzle head 15b has a cylindrical flow baffle 5 with four square openings 5b which are arranged symmetrically in a peripheral direction. Each of four supports 5x forming the openings 5b has a square-shaped cross section. A baffle body 5a having a flat collision surface is removably engaged with one end portion of the flow baffle 5 at a position adjacent to the openings 5b. A nozzle 4 is removably and rotatably engaged with the other end portion of the flow baffle 5. A collision angle is about 90 and a collision distance is set in the above-mentioned range. Since the baffle body 5a is removably engaged with the flow baffle 5, when the baffle body 5a is worn, it can be easily replaced with a new one. Therefore, reliability of execution of WJP can be maintained. In this nozzle head 15b, a jet 3 having cavitation bubbles collides with the collision surface of the baffle body 5a and is discharged from the four openings 5b as four collision jets 9a. Therefore, it is possible to execute the WJP simultaneously to a plurality of objects to be treated which are disposed opposite to the four openings 5b. In this case, since velocity of the collision jets 9a in an axial direction becomes almost zero, a strong water-hammering effect and a turbulent flow are generated, and an vortex flow and a separation flow generated in the collision jet become strong. In this nozzle head 15b, by making width of each opening 5b wider, the collision jets 9a can be discharged in approximately radial directions. In this case, the nozzle head 15b can make an almost omni-directional discharge which is suitable for executing the WJP to an entire inner surface of a cylinder. Therefore, by discharging the jet from this nozzle head to a peripheral weld portion on an inner surface of such a tube with a small diameter, it is possible to execute the WJP simultaneously to the entire peripheral weld portion without rotating this nozzle head from outside. Also, by increasing the number of the openings 5b, the collision jets 9a can be discharged in approximately radial directions. Further, in this nozzle head 15b, since the openings 5b are made longer in the axial direction, the jet 3 can draw water near the openings 5b. Therefore, since cavitation bubbles contained in the jet 3 can grow largely before the collision with the baffle body 5a, the improvement effect of the residual stress by the collision jet becomes higher. Another example of a four-sided discharging type nozzle head according to the present invention is explained by FIG. 6C. FIG. 6C shows a cross sectional view which corresponds to the Axe2x80x94A cross sectional view of FIG. 6A. In this nozzle head, each of four supports 5x forming the openings 5b has curved sides as shown in FIG. 6C. As a result, the support 5x has an almost parallelogram-shaped cross section. The collision jets 9a become to have velocity components in both a radial direction and a peripheral direction by passing through this openings 5b. That is, the collision jets 9a become a revolving flow. In this nozzle head, since the collision jets 9a become the revolving flow, the collision jets 9a can go around to portions which are not disposed opposite to the openings. Further, the nozzle 4 is not rotated but the flow baffle 5 is rotated on its axis by a reaction force to the revolving flows. Therefore, this nozzle head is more suitable for executing the WJP to the entire inner surface of the cylinder than that shown in FIG. 6B. That is, this nozzle head can make an almost omni-directional discharge of the collision jets. Another example of a four-sided discharging type nozzle head according to the present invention is explained by FIG. 7. FIG. 7A shows a cross sectional view which corresponds to FIG. 6B. FIG. 7B and FIG. 7C show a Bxe2x80x94B cross sectional view and a Cxe2x80x94C cross sectional view of FIG. 7A, respectively. The other elements of this nozzle head are almost the same as FIG. 6A. As shown in FIG. 7A, this nozzle head has a collision surface with four spiral grooves 5c which are symmetrical with respect to an central axis of the collision surface. As shown in FIG. 7C, each groove 5c has a V-shaped cross section. In this nozzle head, the collision jet 9a discharged from the opening is given a velocity component in a peripheral direction by the groove 5c. That is, the collision jets 9a become a revolving flow. As a result, the collision jets 9a can go around to portions which are not disposed opposite to the openings. Therefore, this nozzle head is also suitable for executing the WJP to the entire inner surface of the cylinder. Further, if the spiral grooves 5c are replaced with spiral projections, the same effect can be attained. In FIG. 7A, the spiral grooves 5c are originated from positions which are separated from the central axis of the collision surface. If the spiral grooves 5c are originated from the central axis of the collision surface, since vortex flows and separation flows contained in the collision jets 9a become stronger, the collision jets can become collision jets containing cavitation bubbles with high collapse pressures. Therefore, higher improvement effect of the residual stress can be attained. Further, by combining the spiral grooves 5c with the supports 5x shown in FIG. 6C, the peripheral velocity component of the collision jet 9a becomes higher and the rotation speed of the flow baffle 5 on its axis also becomes higher. Therefore, the improvement effect of the residual stress can be attained more effectively. Another example of a four-sided discharging type nozzle head according to the present invention is explained by FIG. 7D. FIG. 7D shows a longitudinal sectional view which corresponds to FIG. 7B. The other elements of this nozzle head are almost the same as FIG. 6A. This nozzle head has a recessed baffle body 5a which has a recess with a concave cross section as the collision surface. The recess is in shape of cone with an apex angle of at least 90(preferably at least 120) in a longitudinal cross section thereof. When a jet 3 collides with the collision surface, velocity of the jet 3 in a collision direction (a downward direction in FIG. 7D) becomes zero on the collision surface, and then the jet 3 changes to a collision jet 9a with a velocity component in direction (an upward direction in FIG. 7D) opposed to that of the jet 3. Since a change in velocity from the jet 3 to the collision jet 9 becomes large by setting the apex angle in the above range, a water-hammering effect occurs strongly on the collision surface. Therefore, part of cavitation bubbles collapse strongly on the collision surface. The remaining cavitation bubbles, which are not collapsed on the collision surface, grow in a strong vortex flow and a strong separation flow included in the collision flow 9a, and are discharged. Also, in this nozzle head, by forming spiral grooves (or spiral projections) as shown in FIG. 7A on the collision surface, it is possible to give a revolving flow to the collision jet 9a and also generate the vortex flow and the separation flow more strongly. As a result, an improvement effect of the residual stress which is high and almost uniform in the peripheral direction can be obtained. As a modification of FIG. 7D, the collision surface can be formed into a projecting surface (shape). In this case, the top of the projecting surface breaks a central flow in the jet 3 and generates cavitation bubbles. Further, it becomes easy to form grooves (or projections) like FIG. 7A on the collision surface by machining. The second embodiment, in which the WJP method according to the present invention is applied to a weld portion of a water-level measuring nozzle in a BWR, is explained using FIG. 8. FIG. 8 is a longitudinal sectional view which shows a state that a nozzle head 15b is set in a water-level measuring nozzle 35. An object of the WJP in this embodiment is a weld portion 38 between a nozzle 36 and a safe end 37 in the water-level measuring nozzle 35 mounted in a RPV 13. The nozzle head 15b shown in FIG. 7D is used in this embodiment. A central flow (a flow near a central axis) in a jet 3 changes its flow direction by a collision with a central portion of a recessed surface (collision surface) and then flows along the recessed surface, thereby a strong turbulent flow is generated by interference between the direction-changed flow and an outer flow in the jet 3. A collision jet generated like this flows toward the RPV 13 (a right side in FIG. 8) in the water-level measuring nozzle 35, and is finally discharged into the RPV 13 because a leading end of the water-level measuring nozzle 35 is closed with a valve 37a. An apparatus used for execution of the WJP to the weld portion 38 in the water-level measuring nozzle 35 is explained using FIG. 9. This apparatus has a nozzle head drive unit 39 for moving the nozzle head 15b to an object to be treated, a frame 40 for supporting the nozzle head drive unit 39 at a level of the water-level measuring nozzle 35, a high-pressure hose 42 and a booster pump 43 for supplying pressurized water to a nozzle 4, a water supply hose 44 for supplying water to the booster pump 43, and a control panel 45 for controlling the nozzle head drive unit 39 and the booster pump 43. The WJP is executed using the above apparatus in accordance with the following steps. (1) Disconnection: A top head of the RPV, a steam drier, a shroud head and fuel assemblies are removed from the RPV. In this state, the RPV 13 and a reactor well are filled with core water 22. (2) Setting of nozzle head drive unit: The nozzle head drive unit 39 is mounted on the frame 40. The nozzle head drive unit 39 is lowered in the frame 40 by an assisting hoist 21, and is set at a position of the water-level measuring nozzle 35. (3) Preparation for execution of WJP: This step has next steps of a) to c). a) Setting of WJP apparatus: The nozzle head 15b mounted at a top end of the nozzle head drive unit 39 is inserted in the water-level measuring nozzle 35. The control panel 45 and the booster pump 43 are disposed on an operation floor. The booster pump 43 is connected to a source water tank 46 by the water-supply hose 44. The booster pump 43 is connected to a WJP main body by the high-pressure hose 42. Wiring between these devices are laid out, and these devices are adjusted. b) Setting of execution conditions: A flow rate and a discharging period (time) of the jet, a moving speed and a moving range of the nozzle head in an axial direction, and a turning speed and a turning range of the nozzle head in a peripheral direction are set. c) Confirmation of operation of apparatus: The nozzle head 15b is moved according to the setting conditions in a state in which the jet is not discharged, to confirm whether or not the execution range is suitable, the nozzle head 15b is smoothly moved, and the like. (4) Execution of WJP: A jet is discharged to start the execution of the WJP. (5) Confirmation of execution of WJP: This step has next steps of a) to b). a) Removal of nozzle head: The nozzle head 15b is removed from the water-level measuring nozzle 35. b) Confirmation of execution of WJP: A monitor camera 47 is inserted in the water-level measuring nozzle 35. It is confirmed by a monitor TV 48 that the WJP is suitably executed. The suitably executed state is recorded in a monitor video 49. (6) Withdrawal of WJP apparatus: This step has next steps of a) to b). a) Withdrawal of monitor camera: The monitor cameral 48 is removed from the water-level measuring nozzle 35 to be withdrawn. b) Withdrawal of WJP apparatus: Piping and wiring between the above devices are removed. The devices, pipes for piping, and wires for wiring are withdrawn. (7) Synchronization: The fuel assemblies, the shroud head, the steam drier, and the top head of the RPV are lowered and assembled to be restored. By executing (applying) the WJP with the above steps to the weld portion of the water-level measuring nozzle in the RPV filled with the core water, it is possible to collapse cavitation bubbles with high collapse pressures on a surface of the weld portion. Accordingly, the residual stress on the surface of the weld portion can be improved and a damage such as the SCC can be prevented. Another example of a four-sided discharging type nozzle head according to the present invention is explained by FIG. 10. FIG. 10 shows a schematic configuration view of this nozzle head. This nozzle head has a turning vane 5d adjacent to the baffle body 5a on an opposite side to the nozzle. The turning vane 5d and the baffle body Sa have the same central axis. That is, this nozzle head has the flow baffle 5 with the turning vane 5d. The other elements of this nozzle head are almost the same as FIG. 6A. In this case, the turning vane 5d is turned by the collision jet which changed its flow direction by the collision with an object to be treated, and this rotation of the turning vane 5d assists a rotation of the baffle body 5a on its axis. The third embodiment, in which the WJP method according to the present invention is applied to an inner surface of a horizontal weld portion (or line) of an ICM housing in a BWR, is explained using FIG. 11. FIG. 11 is a schematic configuration view which shows a state that a nozzle head 15c with a back-flow obstructive plate 10 is set at the inner surface of the horizontal weld portion 17a of the ICM housing 1. As shown in FIG. 4A, the ICM housing 1 pierces a bottom head 26 of the RPV 13 and is fixed to the bottom head 26. The nozzle head 15c corresponds to the nozzle head 15b (shown in FIG. 8) to which the back-flow obstructive plate 10 is added on a nozzle side. Since the nozzle head 15c has the back-flow obstructive plate 10, a sealing portion located at a lower end of the ICM housing 1 is protected for sealing water. In this nozzle head 15c, the collision jet, which changed its flow direction opposite to an initial flow direction of the jet 3 by the collision with the buffle body 5a, can change (be repelled) its flow direction to the initial flow direction by a collision with the back-flow obstructive plate 10. Interference between this repelled collision jet and the initial collision jet makes a turbulent flow, and this turbulent flow can make the peening effect higher. As shown in FIG. 11, an apparatus used for execution of the WJP to the horizontal weld portion 17a of the ICM housing 1 has a lifting shaft 6a with a lifting guide 14 mounting the nozzle head 15c, a nozzle head drive unit 16 having a nozzle rotating means 16a provided at a lower end of the lifting shaft 6a and a nozzle lifter 16b, a high-pressure hose 7 and a booster pump 18 for supplying pressurized water to a nozzle 4, a water supply hose 19 for supplying water to the booster pump 18, and a control panel 20 for controlling the nozzle head drive unit 16 and the booster pump 18. The WJP is executed using the above apparatus in accordance with the following steps. (1) Disconnection: A top head of the RPV, a steam drier, a shroud head, fuel assemblies and control rods are removed from the RPV. In this state, the RPV 13 and a reactor well are filled with core water 22. (2) Water sealing for upper end of ICM guide tube: The upper end of the ICM guide tube above the ICM housing 1 shown in FIG. 1A is plugged for sealing water. (3) Removal of ICM detector: The ICM detector (not shown) contained in the ICM guide tube is removed from the lower end of the ICM housing 1. (4) Confirmation of welding position: An ultrasonic sensor (not shown) or the like is inserted from the lower end of the ICM housing 1 to confirm a position of the horizontal weld portion 17a and an execution range of the WJP. (5) Preparation for execution of WJP: This step has next steps of a) to e). a) Setting of WJP apparatus: A nozzle drive shaft 16c mounting the nozzle head 15c at the leading end is inserted in the ICM housing 1. The nozzle head drive unit 16, control panel 20 and the booster pump 18 are disposed as shown in FIG. 4A. The booster pump 18 is connected to a source water tank (not shown) by the water supply hose 19. The booster pump 18 is connected to a WJP main body by the high-pressure hose 7. Wiring between these devices is laid out, and these devices are adjusted. b) Setting of execution conditions: A flow rate and a discharging period (time) of the jet, a moving speed and a moving range of the nozzle head in an axial direction, and a turning speed and a turning range of the nozzle head in a peripheral direction are set. c) Confirmation of operation of apparatus: The nozzle head 15c is moved according to the setting conditions in a state in which the jet is not discharged, to confirm whether or not the execution range is suitable, the nozzle head 15c is smoothly moved, and the like. d) Release of sealing of upper end of ICM guide tube: The plugging of the upper end of the ICM guide tube is released. e) Trial discharge of jet: The trial discharge of the jet 3 is performed for conforming looseness of pipes, a vibrational state, and the like. In this way, the setting of the WJP apparatus is terminated. (6) Execution of WJP: The jet 3 is discharged to start execution of the WJP to the horizontal weld portion 17a. (7) Confirmation of execution of WJP: This step has next steps of a) to d). a) sealing for upper end of ICM guide tube: The upper end of the ICM guide tube is plugged for sealing water. b) Removal of nozzle drive shaft: The nozzle drive shaft 16c is removed from the ICM housing 1. c) Setting of monitor camera: The monitor camera 30 is inserted in the ICM housing 1 and is set in co-operation with the monitor video 31. d) Confirmation of execution of WJP: It is confirmed that the WJP is suitably executed by the monitor camera 30. (8) Withdrawal of WJP apparatus: This step has next steps of a) to b). a) Withdrawal of monitor camera: The monitor camera 30 is removed from the ICM housing 1 to be withdrawn. b) Withdrawal of WJP apparatus: The wiring and piping between the above devices are removed, and the devices, pipes for piping, and wires for wiring are withdrawn. (9) Mounting of ICM detector: The ICM detector is inserted from the lower end of the ICM housing 1 to be mounted. (10) Release of sealing of upper end of ICM guide tube: The plugging of the upper end of the ICM guide tube is released. In this way, the execution of the WJP is terminated. (11) Synchronization: The fuel assemblies, the control rods, the shroud head, the steam drier and the top head of the RPV are lowered and assembled to be restored. By executing (applying) the WJP with the above steps to the horizontal weld portion of the ICM housing in the RPV filled with the core water, it is possible to collapse cavitation bubbles with high collapse pressures on a surface of the horizontal weld portion. Accordingly, the residual stress on the surface of the horizontal weld portion can be improved and a damage such as the SCC can be prevented. In this embodiment, the nozzle head 15c with the back-flow obstructive plate 10 is used. However, the nozzle head 15a and 15b shown in FIGS. 2 and 6 are also can be used in the above steps. The fourth embodiment, in which the WJP method according to the present invention is applied to an inner surface of a horizontal weld portion of an ICM housing in a BWR, is explained using FIG. 12. In the third embodiment, the nozzle head is inserted from the lower end of the ICM housing, however, in this embodiment, the nozzle head is inserted from the upper end of the ICM housing. In this embodiment. The nozzle head 15b shown in FIG. 8 is used. FIG. 12 is a schematically constructional view which shows a state that the nozzle head 15b is set at the inner surface of the horizontal weld portion 17a of the ICM housing 1. Executing steps of WJP according to this embodiment is explained below. (1) Disconnection: A top head of the RPV, a steam drier, a shroud head, fuel assemblies and control rods are removed from the RPV. In this state, the RPV 13 and a reactor well are filled with core water 22. (2) Water sealing for upper end of ICM guide tube and removal of ICM detector: This step has next steps of a) to b). a) The upper end of the ICM guide tube above the ICM housing 1 shown in FIG. 1A is plugged for sealing water. In FIG. 12, 34 is a core support. b) The ICM detector (not shown) contained in the ICM guide tube 1a is removed from the lower end of the ICM housing 1. (3) Water sealing for lower end of ICM housing and release of sealing for upper end of ICM guide tube: This step has next steps of a) to b). a) A closing flange 32 is mounted at the lower end of the ICM housing 1 for sealing water. b) The plugging of the upper end of the ICM guide tube is released. (4) Confirmation of welding position: An ultrasonic sensor (not shown) or the like is inserted from the upper end of the ICM guide tube 1a to confirm a position of the horizontal weld portion 17a and an execution range of the WJP. (5) Preparation for execution of WJP: This step has next steps of a) to d). a) Setting of WJP apparatus: A lifting shaft 6a mounting the nozzle head 15b at the leading end is inserted in the ICM housing 1 from an upper side. A nozzle head drive unit 16, a control panel 20 and a booster pump 18 are disposed. The booster pump 18 is connected to a source water tank (not shown) by the water supply hose 19. The booster pump 18 is connected to a WJP main body by a high-pressure hose 7. Wiring between these devices is laid out, and these devices are adjusted. The arrangement of these devices in this case are substantially the same as those shown in FIG. 4A. Therefore, the explanation thereof is omitted. b) Setting of execution conditions: A flow rate and a discharging period (time) of the jet, a moving speed and a moving range of the nozzle head in an axial direction, and a turning speed and a turning range of the nozzle head in a peripheral direction are set. c) Confirmation of operation of apparatus: The nozzle head 15b is moved according to the setting conditions in a state in which the jet is not discharged, to confirm whether or not the execution range is suitable, the nozzle head 15c is smoothly moved, and the like. d) Trial discharge of jet: The trial discharge of the jet 3 is performed for conforming looseness of pipes, a vibrational state, and the like. In this way, the setting of the WJP apparatus is terminated. (6) Execution of WJP: The jet 3 is discharged to start execution of the WJP to the horizontal weld portion 17a. (7) Confirmation of execution of WJP: This step has next steps of a) to c). a) Removal of nozzle drive shaft: The nozzle drive shaft (not shown) is removed from the ICM housing 1. b) Setting of monitor camera: The monitor camera is inserted in the ICM housing 1 and is set in co-operation with the monitor video. c) Confirmation of execution of WJP: It is confirmed that the WJP is suitably executed by the monitor camera. (8) Withdrawal of WJP apparatus: This step has next steps of a) to b). a) Withdrawal of monitor camera: The monitor camera is removed from the ICM housing 1 to be withdrawn. b) Withdrawal of WJP apparatus: The wiring and piping between the above devices are removed, and the devices, pipes for piping, and wires for wiring are withdrawn. (9) Water sealing for upper end of ICM guide tube, mounting of ICM detector, and release of sealing of upper end of ICM guide tube: This step has next steps of a) to c). a) The upper end of the ICM guide tube 1a is plugged for sealing water. b) The closing flange 32 at the lower end of the ICM housing 1 is removed, and the ICM detector is inserted to be mounted. c) The plugging of the upper end of the ICM guide tube 1a is released. In this way, the execution of the WJP is terminated. (10) Synchronization: The fuel assemblies, the control rods, the shroud head, the steam drier and the top head of the RPV are lowered and assembled to be restored. In this embodiment, since the nozzle head 15b having the baffle body 5a with the recessed surface (collision surface) is used, a central flow in the jet 3 changes its flow direction by the collision with a central portion of the recessed surface and then flows along the recessed surface, thereby a strong turbulent flow is generated by interference between the direction-changed flow and an outer flow in the jet 3. A collision jet generated like this flows upward in the ICM housing 1, and is finally discharged into the RPV 13 because the closing flange 32 is mounted at the lower end of the ICM housing 1. Since the collapse pressures of the cavitation bubbles become higher by a strong turbulent flow generated near the recessed surface, a high improvement effect of the residual stress can be obtained. Accordingly, in this embodiment, the residual stress on the surface of the horizontal weld portion of the ICM housing can be improved and damage such as the SCC can be prevented like in the third embodiment. FIG. 13 shows one example of the improvement effect of the residual stress by using the four-sided discharging type nozzle head 15b shown in FIG. 6A. The nozzle 4 having an outer diameter of 30 mm and a hole diameter of 2 mm is used. The baffle body 5a is arranged so as to make the collision distance of 80 mm and the collision angle of 90. FIG. 13 shows a measurement result of the residual stress on an inner surface of a test tube with an inner diameter of 38 mm after executing the WJP to the inner surface of the test tube using this nozzle head 15b. The WJP is executed in a condition that the nozzle head is moving to an axial direction (Z-direction) of the test tube. In FIG. 13, a vertical axis is a relative measurement value of the residual stress, and a horizontal axis is a distance from a center position in an executing region of WJP in the Z-direction. A positive residual stress is a tensile residual stress, and a negative residual stress is a compressive residual stress. The test tube is divided into three pieces, and its surface is subjected to surface grinding so as to have a tensile residual stress of about 400 MPa as an initial residual stress. As shown in FIG. 13, the initial tensile residual stress is improved to the compressive residual stress by executing the WJP. Since it is known that no SCC and no fatigue fracture occur under the compressive stress, it is possible to prevent the SCC and the fatigue fracture by applying the above-mentioned WJP in accordance with the present invention. While the WJP methods according to the present invention are applied to the structural members in the RPV in the above-mentioned embodiments, objects applied by these WJP methods are not limited in this. That is, these WJP methods can be applied to tubes in a nuclear plant, general industrial machines and ships. The fifth embodiment, in which the WJP method according to the present invention is applied to weld portions of a water-level measuring nozzle in a BWR, is explained using FIGS. 14 through 17. As shown in FIG. 15, a RPV 13 is provided with a lower water-level measuring nozzle 35a, a middle water-level measuring nozzle 35b, and an upper water-level measuring nozzle 35c. The present embodiment is an example in which a WJP apparatus (a preventive maintenance apparatus) of the present invention is applied to weld portions of the lower water-level measuring nozzle 35a. As for the upper water-level measuring nozzle 35c and the middle water-level measuring nozzle 35b, the WJP apparatus shown in FIG. 8 can be applied to them. As shown in FIG. 14, the WJP apparatus employed by the present embodiment comprises a nozzle 4, a nozzle head 15d, a nozzle head driver 60, a nozzle drive device 39, a fixing apparatus 61, etc. The structure of the nozzle head 15d is substantially the same as that of the nozzle head 15b shown in FIG. 6. The nozzle head 15d is different from the nozzle head 15b in that one end (the end portion on the nozzle side) of the nozzle head 15d extends to the nozzle head driver 60 (to the left side of the nozzle 4 in FIG. 14). The nozzle head driver 60 comprises driver members 60a, 60b, 60c, etc. The driver member (element) 60a forms a pantograph-like link mechanism and is connected to the driver member 60c and the nozzle drive device 39 by use of pin-like connecting members 60d and 60g, respectively. The driver member 60c has two guide holes 60e and is movable in the axial direction of the nozzle 4 along two rods 61b that penetrate through the guide holes 60e. The driver member 60b has a cylindrical structure whose one end is connected to the nozzle head 15d and the other end is connected to the driver member 60c. The nozzle drive device 39 has a mechanism for extending (expanding) and contracting the entire driver member 60a by rotating the link mechanism of the driver member 60a symmetrically in an arrow direction indicated in FIG. 14 using the connecting member 60g as the rotational axis. The driver member 60c can be moved to the nozzle side (to the right side in FIG. 14) by extending the driver member 60a (that is, decreasing the angle xcex8) by use of the nozzle drive device 39, while the driver member 60c can be moved to the nozzle drive device side (to the left side in FIG. 14) by contracting the driver member 60a (that is, increasing the angle xcex8) by use of the nozzle drive device 39. Thus, by controlling the angle xcex8 of the link mechanism formed by the driver member 60a using the nozzle drive device 39, it is possible to control the position of the driver member 60c in the axial direction of the nozzle 4 as well as controlling the positions of the nozzle 4 and the nozzle head 15d in the axial direction of the nozzle 4. That is, it is possible to stop the nozzle 4 and the nozzle head 15d at desired positions in their axial direction to position them. The control signal and power necessary to perform the above control are supplied to the nozzle drive device 39 through a control cable 62. It should be noted that the driver member 60b may be configured so as to be extendable and contractible i.e. telescopic, in the axial direction of the nozzle 4 (the nozzle head 15d). In this case, the positions of the nozzle 4 and the nozzle head 15d can be controlled by use of the driver members 60a and 60b. The fixing apparatus 61 comprises pads 61a, rods 61b, rod drivers 61c, etc. In this WJP apparatus, the pads 61a are members in contact with an external side of a shroud upper body 23a. Also in this WJP apparatus, the rods 61b function as both the guides for the above driver member 60c and members in contact with an internal side of the RPV 13. The tips of the rods 61b (the end portions on the RPV side) may be provided with members such as the pads 61a thereon as necessary. The rod drivers 61c have a mechanism for extending and contracting the rods 61b in the axial direction of the nozzle 4. With this arrangement, the rods 61b obtains a structure extendable and contractible in the axial direction of the nozzle 4. A method for applying a WJP process to the weld portions of the lower water-level measuring nozzle 35a by use of the above WJP apparatus is explained below using FIGS. 16 and 17. The procedure for executing WJP according to the present embodiment is basically the same as that shown in FIG. 5. Furthermore, according to the present embodiment, the state in which the WJP apparatus is installed is substantially the same as that shown in FIG. 9 except that the target to which the WJP process is applied is the lower water-level measuring nozzle 35a. FIGS. 16 and 17 are schematic partial cross-sectional views showing states in which the WJP apparatus of the present embodiment is applied to the lower water-level measuring nozzle 35a. As shown in FIG. 16, the targets in the lower water-level measuring nozzle 35a to which the WJP process is applied are a portion A (a weld heat-affected zone) near a weld portion 38a (J weld portion) between the RPV 13 and a nozzle 36 and a portion B which includes a weld portion 38 between the nozzle 36 and a safe end 37 and the weld heat affected zone around the weld portion 38. That is, portions A and B are target portions to be treated (processed). Since the lower water-level measuring nozzle 35a is situated (positioned) at the same height as the shroud upper body 23a, the space between the shroud upper body 23a and the RPV 13 forms narrow space portions. Therefore, the WJP apparatus is installed in the narrow space portions in a state in which the lengths of the driver member 60a and the rods 61b in the axial direction of the nozzle 4 are set to be shortest (setting their positions at which the lengths are shortest). Specifically, the WJP apparatus is suspended and lowered from the upper portion of the RPV 13 into the narrow space portions so that the positions of the nozzle drive device 39 in the height direction and the circumferential direction in the RPV 13 are aligned with those of the lower water-level measuring nozzle 35a. Then, the rods 61b are extended by use of the rod drivers 61c to fix the WJP apparatus between the shroud upper body 23a and the RPV 13. While monitoring the operation on a monitor camera 47, the driver member 60a is extended by use of the nozzle drive device 39 to position the nozzle head 15d at the position of the target portion A to be treated (processed). With the nozzle head 15d at this position, high-pressure water is supplied through a high-pressure hose 7 to discharge a jet (water jet) 3 from the nozzle 4 so that the WJP process is executed on the target portion A to be treated by use of a collision jet 9a whose direction has been changed by a baffle body 5a. Furthermore, while monitoring the operation on the monitor camera 47, the driver member 60a is further extended by use of the nozzle drive device 39 to position the nozzle head 15d at the position of the target portion B to be treated. This positioning may be realized by extending the driver member 60b. With the nozzle head 15d at this position, the jet 3 is discharged from the nozzle 4 so that the WJP process is executed on the target portion B to be treated by use of the collision jet 9a whose direction has been changed by the baffle body 5a, as in the case with the target portion A to be processed. FIG. 17 shows a state in which the driver members 60a and 60b are extended to position the nozzle head 15d at the position of the target portion B to be treated. To make possible the positioning of the nozzle head 15d as shown in FIG. 17, the outside (outer) diameters of the nozzle head 15d and the driver member 60b are set to be smaller than the inside (inner) diameter of the lower water-level measuring nozzle 35a. After thus executing the WJP process on the target portions A and B to be treated, the driver members 60a and 60b are contracted. Then, the rods 61b are contracted by use of the rod drivers 61c so as to be able to remove the WJP apparatus from the narrow space portions. According to the present embodiment, since the driver members 60a and 60b have a structure extendable and contractible in the axial direction of the nozzle 4 to position the nozzle head 15d in the axial direction, it is possible to surely perform the WJP process even on the weld portions of the lower water-level measuring nozzle 35a situated in the narrow space portions. This application of the WJP process can reduce a tensile residual stress on a surface of the weld portions of the lower water-level measuring nozzle 35a, and can prevent occurrence of stress corrosion cracking (SCC) on the surface thereof. In this embodiment, a nozzle head having a recess like FIG. 7D can be applicable.
	claims	1. A factor estimating device for estimating a factor from a result generated in a target system for diagnosis, said factor estimating device comprising;an estimate knowledge recording part for recording factor estimating knowledge data that correlate one or more candidates for factor to each of a plurality of results that may be generated in said target system and show factor estimating paths from each of said results to each of said candidates corresponding to said each result as knowledge of a network structure having condition branches;inference processing means for carrying out factor estimating process based on said factor estimating knowledge data recorded in said estimate knowledge recording part;item data obtaining means for obtaining data on input item corresponding to conditions contained in said factor estimating knowledge data while said inference processing means carries out said factor estimating process;fitness calculating means for calculating fitness factors based on the data obtained by said item data obtaining means, said fitness factors being indicative of degrees to which said conditions are satisfied;certainty calculating means for calculating for each of the factors a representative value of an assembly of fitness factors corresponding to a condition contained in said factor estimating paths as certainty factor; andinfluence calculating means for calculating influence factor for each of input items indicative of degree of influence on the certainty factor when said data on said input item are obtained regarding a certain input item;wherein said item data obtaining means obtains data on a selected input item by considering the influence factors. 2. The factor estimating device of claim 1 further comprising aimed node determining means for determining as an aimed node, when data obtained by said item data obtaining means satisfy a condition, the node to which said satisfied condition branches;said item data obtaining means obtaining data of an input item selected out of those of input items corresponding to said aimed node and nodes on the downstream side of said aimed node by considering the influence factors. 3. The factor estimating device of claim 2 wherein said aimed node determining means determines an earlier determined aimed node as the aimed node if there is no input item with influence factor higher than a specified value. 4. The factor estimating device of claim 1 further comprising a related item recording part for grouping and recording data on a plurality of related input items;wherein said item data obtaining means obtains not only data on a selected input item by considering the influence factors but also data on input items that belong to same group as said selected input item. 5. The factor estimating device of claim 4 further comprising a related item recording part for grouping and recording data on a plurality of related input items;said item data obtaining means obtaining not only data on said selected input item by considering the influence factors but also data on input items that belong to same group as said selected input item and have influence factors higher than a specified value. 6. The factor estimating device of claim 1 further comprising input control means for obtaining a user's response to a question corresponding to a condition contained in said factor estimating knowledge data;wherein said item data obtaining means obtains said data on said input item based on said response obtained by said input control means. 7. The factor estimating device of claim 6 further comprising:inspection result inputting means for receiving inspection result data from an inspection device that inspects said target system;an inspection result recording part that records said inspection result data received by said inspection result inputting means; andan obtaining method recording part for recording data on an obtaining method indicating whether said data on said input item are obtained either from a user or from said inspection result data or from both said user and said inspection result, as well as said data on said input item;wherein said item data obtaining means obtains said data on said input item based on said data on the obtaining method corresponding to said input item. 8. The factor estimating device of claim 1 that estimates a factor from a no-good result generated in a processing system which carries out processes on a target object. 9. A program storage device readable by a machine, tangibly embodying a program of instructions executable by said machine to a factor estimating device for estimating a factor from a result generated in a target system of diagnosis; said factor estimating device comprising;an estimate knowledge recording part for recording factor estimating knowledge data that correlate one or more candidates for factor to each of a plurality of results that may be generated in said target system and show factor estimating paths from each of said results to each of said candidates corresponding to said each result as knowledge of a network structure having condition branches;inference processing means for carrying out factor estimating process based on said factor estimating knowledge data recorded in said estimate knowledge recording part;item data obtaining means for obtaining data on input item corresponding to conditions contained in said factor estimating knowledge data while said inference processing means carries out said factor estimating process;fitness calculating means for calculating fitness factors based on the data obtained by said item data obtaining means, said fitness factors being indicative of degrees to which said conditions are satisfied;certainty calculating means for calculating for each of the factors a representative value of an assembly of fitness factors corresponding to a condition contained in said factor estimating paths as certainty factor; andinfluence calculating means for calculating influence factor for each of input items indicative of degree of influence on the certainty factor when said data on said input item related are obtained regarding a certain input item;wherein said item data obtaining means obtains data on a selected input item by considering the influence factors. 10. The program storage device of claim 9 wherein said factor estimating device further comprises aimed node determining means for determining as an aimed node, when data obtained by said item data obtaining means satisfy a condition, the node to which said satisfied condition branches;said item data obtaining means obtaining data of an input item selected out of those of input items corresponding to said aimed node and nodes on the downstream side of said aimed node by considering the influence factors. 11. The program storage device of claim 10 wherein said aimed node determining means determines an earlier determined aimed node as the aimed node if there is no input item with influence factor higher than a specified value. 12. The program storage device of claim 9 wherein said factor estimating device further comprises a related item recording part for grouping and recording data on a plurality of related input items;wherein said item data obtaining means obtains not only data on a selected input item by considering the influence factors but also data on input items that belong to same group as said selected input item. 13. The program storage device of claim 12 wherein said factor estimating device further comprises a related item recording part for grouping and recording data on a plurality of related input items;said item data obtaining means obtaining not only data on a selected input item by considering the influence factors but also data on input items that belong to same group as said selected input item and have influence factors higher than a specified value. 14. The program storage device of claim 9 wherein said factor estimating device further comprises input control means for obtaining a user's response to a question corresponding to a condition contained in said factor estimating knowledge data;wherein said item data obtaining means obtains said data on said input item based on said response obtained by said input control means. 15. The program storage device of claim 14 wherein said factor estimating device further comprises:inspection result inputting means for receiving inspection result data from an inspection device that inspects said target system;an inspection result recording part that records said inspection result data received by said inspection result inputting means; andan obtaining method recording part for recording data on an obtaining method indicating whether said data on said input item are obtained either from a user or from said inspection result data or from both said user and said inspection result, as well as said data on said input item;wherein said item data obtaining means obtains said data on said input item based on said data on the obtaining method corresponding to said input item. 16. The program storage device of claim 9 wherein said factor estimating device estimates a factor from a no-good result generated in a processing system which carries out processes on a target object. 17. A method of estimating a factor by a factor estimating device for estimating a factor from a result generated in a target system for diagnosis, said factor estimating device being provided with an estimate knowledge recording part for recording factor estimating knowledge data that correlate one or more candidates for factor to each of a plurality of results that may be generated in said target system and show factor estimating paths from each of said results to each of said candidates corresponding to said each result as knowledge of a network structure having condition branches, said method comprising:an inference step of carrying out factor estimating process based on said factor estimating knowledge data recorded in said estimate knowledge recording part;an item data obtaining step of obtaining data on input item corresponding to conditions contained in said factor estimating knowledge data during said factor estimating process in said inference step;a fitness calculating step of calculating fitness factors based on the data obtained in said item data obtaining step, said fitness factors being indicative of degrees to which said conditions are satisfied;a certainty calculating step of calculating for each of the factors a representative value of an assembly of fitness factors corresponding to a condition contained in said factor estimating paths as certainty factor; andan influence calculating step of calculating influence factor for each of input items indicative of degree of influence on the certainty factor when said data on said input item are obtained regarding a certain input item;wherein said item data obtaining means obtains data on a selected input item by considering the influence factors.
	summary
044180357	claims	1. In a nuclear power reactor having a fuel core and a sensor positioned within a body of reactor coolant in thermal contact with an outer sheath of the sensor to establish a heat sink for a body of the sensor internally heated by gamma radiation and having thermal resistance regions formed therein within spaced measurement zones and a thermocouple device extending through said heated body having at least two spaced junctions in each of the measurement zones producing differential signal voltages of one polarity in response to uniform cooling of the outer sheath by the body of coolant in the reactor, the improvement residing in one of the junctions in each of the measurement zones being located vertically above the other of the junctions to produce a differential signal voltage opposite in polarity to said one polarity in response to depletion of the body of reactor coolant to a level below said one of the junctions, and voltage monitoring means connected to the spaced junctions in each of the measurement zones for indicating coolant condition in the reactor. 2. The combination as defined in claim 1 wherein said thermocouple device includes an electrically grounded cladding enclosing the spaced junctions, said voltage monitoring means including first voltage indicating means connected across said spaced junctions for measuring heat flow rate in the heated body and second voltage indicating means connected between ground and said one of the junctions for measuring sensor temperature. 3. The improvement as defined in claim 2 including alarm means connected to the spaced junctions for indicating loss of coolant in response to a polarity reversal of the voltage across said spaced junctions. 4. The improvement as defined in claim 3 wherein said one of the junctions is located in spaced adjacency above the thermal resistance region in each of the measurement zones. 5. The improvement as defined in claim 1 wherein said one of the junctions is located in spaced adjacency above the thermal resistance region in each of the measurement zones. 6. The improvement as defined in claim 1 including electrical heating means embedded within the body for selectively increasing the internal heating thereof. 7. In a nuclear power reactor having a fuel core and a gamma sensor positioned within a body of reactor coolant in thermal contact therewith, said sensor having a thermocouple device provided with spaced junctions and means connected thereto for registering a differential signal voltage, the improvement residing in location of the junctions relative to each other producing a reversal in polarity of the differential signal voltage in response to depletion of the body of coolant to a level below one of the junctions, and means connected to said spaced junctions for monitoring heat transfer conditions externally of the sensor. 8. The improvement as defined in claim 5 wherein said one of the junctions is faster responding than the other of the junctions and is positioned above the other of the junctions. 9. The improvement as defined in claim 8 wherein said sensor includes a thermal resistance region axially aligned with the other of the junctions below the faster responding junction. 10. The improvement as defined in claim 7 wherein said monitoring means includes indicator means for detecting loss of reactor coolant in response to said reversal in polarity of the differential signal voltage. 11. The improvement as defined in claim 7 including electrical heating means embedded in the sensor for selectively increasing the differential signal voltage. 12. In a combination with a nuclear power reactor having an elongated, coolant containing vessel provided with a dome at an upper end thereof, and a lower end through which an elongated sensor is inserted for monitoring power generated by a fuel core positioned within the vessel in spaced relation below the dome, the improvement comprising means projecting into the dome for protectively enclosing the sensor extended vertically into the dome from the fuel core, and means connected to the sensor for monitoring heat transfer conditions of coolant within the dome. 13. The improvement as defined in claim 12 wherein said sensor includes a gamma radiation heated body and a thermocouple device embedded therein, to which the monitoring means is connected for monitoring both the heat transfer conditions and power generated within the fuel core. 14. The improvement as defined in claim 13 wherein said protective enclosing means is provided with openings through which the sensor is externally exposed to coolant throughout within the dome. 15. The improvement as defined in claim 14 wherein said thermocouple device includes at least two spaced temperature measuring junctions connected to the monitoring means and located within the dome, one of said two junctions responding more rapidly to changes in heat flow through the heated body of the sensor than the other of the junctions, said faster responding one of the junctions being located vertically above the other of the junctions to produce a reversal in polarity of voltage across the junctions as measured by the monitorng means in response to depletion of the coolant to a level below said faster responding one of the junctions. 16. The improvement as defined in claim 12, wherein said sensor includes a gamma radiation heated body and a thermocouple device embedded therein having at least two spaced temperature measuring junctions connected to the monitoring means and located within the dome, one of said two junctions responding more rapidly to changes in heat flow through the heated body of the sensor than the other of the junctions, said faster responding one of the junctions being located vertically above the other of the junctions to produce a reversal in polarity of voltage across the junctions as measured by the monitoring means in response to depletion of the coolant to a level below said faster responding one of the junctions. 17. In a nuclear power reactor having a fuel core and sensor means positioned within a body of liquid coolant in thermal contact therewith, said sensor means including vertically spaced thermocouple junctions, the improvement residing in a liquid level monitor comprising means connected to said junctions for indicating a differential signal voltage therebetween in response to depletion of said body of liquid coolant below at least one of the junctions, heater means mounted adjacent to the sensor means for increasing said differential signal voltage to a triggering level, and alarm means connected to said indicating means for registering coolant loss in response to the differential signal voltage above said triggering level. 18. The combination of claim 18 wherein a differential voltage of opposite polarity is developed at said thermocouple junctions when the liquid coolant is in thermal contact with both of said junctions to monitor local power distribution. 19. In combination with a power distribution sensor for the fuel core of a nuclear power reactor having a body of coolant, the sensor including a gamma radiation heated body, in heat transfer relation to the coolant, within which a varying temperature distribution is established, thermoouple junctions mounted within the body at spaced locations, and monitoring means connected to said thermocouple junctions for measuring temperature differentials in the heated body reflecting localized power generation, the improvement comprising additional means connected to the thermocouple junctions for detecting changes in the temperature differentials caused by changes in relative coolant conditions at said spaced locations, and alarm means connected to the additional detecting means for indicating a drop in coolant level within the reactor.
055047882	description	DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The present invention is described with reference to the enclosed Figures wherein the same reference numbers are utilized where applicable. Referring to FIG. 2, the support plate inspection device 10 of the present invention is illustrated. It is to be appreciated by those skilled in the art that the present invention will be utilized to facilitate the easy and rapid inspection of the support plates and tubes of a nuclear steam generator. Typically, the tubes form rows of tube members 24, 24a which are separated by lanes 21, and are retained in position by a plurality of support plates 26. The bottom of each lane typically includes one or more access ports 18 through the which the quenching water exits the generator. This water may have impurities which may corrode or pierce the pipes of the tube sheets, thus resulting in leaks of radioactive superheated water. Such leaks may not be visible to the human eye. Because of the limited access ports, it is difficult for direct human inspection of the pipes to take place. The support plate inspection device 10 of the present invention, in a preferred embodiment, comprises boom means 12 for extending into an access port 18 of a steam generator and into a lane 21 separating two tube sheet members 24, 24a. The boom means is uprightable within the lane 21. A video camera means 30 is attached to the boom means for inspecting the tube members 24, 24a and support plates 26 within the lane 21 when said boom means is uprighted. In a more preferred embodiment, the boom means 22 is multi-sectioned and includes first boom means 14 rotatably coupled to second boom means 16. Boom means 14, 16 are joined by a rotatable joint or connector means 20 such as an elbow joint. The rotatable connector 20 may be activated mechanically via a hand crank, or by means of a pneumatic or hydraulic activator. As shown in FIG. 2, rotatable connector means 20 facilitates the selective vertical rotation of the second boom means 16 with respect to the first boom means 14 within the lane 21. While the present invention has been illustrated in the context of a rotatable elbow joint, it is to be appreciated that the present invention may be utilized with any means for rotating maneuvering the second boom means upwardly relative to first boom means. The first and second boom means 14, 16 are, in one embodiment cylindrical booms members, which enter the steam generator through access port 18 in the wall 23 of the steam generator, and extended within the lane 21 separating two rows of tube members 24, 24a. Wall 23 is typically constructed from steel. The access port may be 1", 2", 4", or 6" in diameter. By enabling access of the inspection device of the present invention through the 1" or 2" access ports, the present invention provides for the inspection of the complete secondary side of the tube sheet and the support plates. As shown in FIGS. 3, 4 and 5, second boom means 16 preferably comprises a plurality of telescoping members 22 which are extendable pneumatically or hydraulically. The multiple telescoping members 22 facilitate the selective vertical or longitudinal adjustment of the second boom means 16 within the tube lane 21. Telescoping members 22 facilitate a full visual inspection of the reactor support plates 26 and tube members 24, 24a. In a preferred embodiment, the second boom means 16 should have telescoping members 22 of sufficient quantity and length to permit the vertical extension of the second boom means 16 of up to approximately 32 feet. This is the typical height of the tubes and will facilitate inspection of the entire tube sheet and all of the support plates. The support plate inspection device 10 further includes a video camera 30 which is attached at or near the distal end of the second telescoping boom means 16, and which transmits video images to a TV monitor located outside of the steam generator. In a preferred embodiment, the video camera will incorporate CCD (charge-coupled device) technology. The advent of CCD (charge-coupled devices) image transducers has permitted television cameras to be fabricated in very small sizes. The CCD detector assembly is positioned to receive optical images from the camera lens so that it can convert the components of the received image to corresponding electrical signals. Electrical circuitry associated with the detectors converts the image component signals to standard video signals for use by television receiver/monitors. In the present invention, the CCD circuitry may, for example, comprise Sony Model A-7560-026A, which functions to convert optical images received from a lens assembly into electrical video signals. The lens assembly of the preferred embodiment, may, for example, comprise Sony Model VCL08SBYA. The distal end of the second boom means 14 supporting the CCD camera further incorporates a pan and tilt means 32, to which video camera 30 is attached. As shown in FIGS. 6 and 7, pan and tilt means 32 facilitates the horizontal 32a and vertical rotation 32b of the video camera 30. In a preferred embodiment, the video camera should be able to pan 359.degree. and tilt approximately 180.degree.. In this manner, the video camera 30 can completely inspect the tube members 24, 24a and support plates 26. In a preferred embodiment, the video camera 30 will also preferably incorporate an auto focus mechanism 34 which, along with the pan and tilt means 32, will be controlled by an operator with a joy stick (not shown) on the outside of the steam generator. FIGS. 6 and 7 further illustrate connecting cables 36 which facilitate the remote operation of the auto focus and pan and tilt mechanism from the joy stock. The cables 36 from the video camera 30 lead to the closed circuit TV monitor located on the outside of the steam generator. Finally, as shown in FIG. 7A, the present invention further includes means 38 for cleaning the tubes 24, 24a and support plates 26. Means 38 will be affixed to the pan and tilt means 32. In a preferred embodiment, means 38 will comprise a nozzle 40 with attached hose 42 which will jet hot water, steam or a chemical cleaner to clean the tube members 24, 24a and support plates 26. The operation of the present invention is now described with reference to the enclosed Figures. As noted above, the present invention is utilized to inspect the support plates 26 and tube members 24, 24a of a nuclear steam generator. Initially, as shown in FIG. 2, the support plate inspection device 10 is inserted through an access port 18 in the wall 23 of the steam generator and through a lane 21 dividing two rows of tube members 24a, 24b. The second telescoping member 16 having the CCD video camera 30 attached thereto is uprighted using rotational connector joint means 20. The rotational joint means 20 may be uprighted using a mechanical crank, or alternatively, with a hydraulic or pneumatic power source. The telescoping second boom means 16 extends upwardly in the lane 21 so as to facilitate the inspection of the support plates and the tube sheet members. The telescoping second boom means 16 can be longitudinally adjusted such that the CCD camera 30 can obtain a full and complete visual inspection of the support plates 26 and complete tubes. The telescoping members 22 should enable the CCD camera to extend vertically approximately 32 feet in order facilitate the full examination of the tubes and support plates. By adjusting the auto focus and pan and tilt means using a joystick situated outside the generator, the CCD camera can fully inspect the tubes 24, 24a sheet and support plates 26. The operator, safely outside the generator, can monitor the inspection on a closed circuit TV camera used in association with the CCD camera 30. By selectively extending the telescoping second boom 16 up to a length approximately 32 feet, the CCD camera 30 can fully inspect each of the four to six support plates which retain the tube sheet members. Means 38 can be utilized to get hot water, steam or chemical cleaner to remove corrosion and dirt from the tube members 24, 24a and support plates 26. When the inspection is completed, the telescoping members 22 are retracted and the second boom means is rotated downward as shown in FIG. 2. The support plate inspection device 10 is withdrawn through access port 18 in wall 23. The procedure may then be repeated by extending the device into another access port 16. The present invention has been described with reference to the enclosed figures and the above-detailed description. It is to be appreciated that numerous modifications and embodiments fall within the spirit of the present invention and that the true nature and scope of the present invention should be determined with reference to the claims appended hereto.
	abstract	Illustrative embodiments provide a reactivity control assembly for a nuclear fission reactor, a reactivity control system for a nuclear fission reactor having a fast neutron spectrum, a nuclear fission traveling wave reactor having a fast neutron spectrum, a method of controlling reactivity in a nuclear fission reactor having a fast neutron spectrum, methods of operating a nuclear fission traveling wave reactor having a fast neutron spectrum, a system for controlling reactivity in a nuclear fission reactor having a fast neutron spectrum, a method of determining an application of a controllably movable rod, a system for determining an application of a controllably movable rod, and a computer program product for determining an application of a controllably movable rod.
051261006	abstract	A unique and optimal method for assessing the feasibility of employing chemical decontamination processes to remove crud from nuclear reactor primary systems without adversely affecting the integrity of the system components or piping during further reactor operation is disclosed. Materials used to construct such components and piping are exposed to several cycles of simulated decontamination processing with a test loop constructed to simulate a range of full system decontamination process conditions. The material specimens are then removed and tested to assure that the particular decontamination processing system has no adverse effects on the materials used.
056174578	description	DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the figures of the drawing in detail and first, particularly, to FIG. 1 thereof, there is seen a multiplicity of fuel assemblies 2 which are disposed inside a reactor pressure vessel 1. The fuel assemblies are supported by tops or top fittings 3 of the fuel assemblies at apertures or meshes 4 in a grid plate 5. Feet or bottom fittings 6 of the fuel assemblies rest adjacently on a lower core support 7 with a flow distribution plate 7' at a bottom 8 of the pressure vessel 1. A plenum 10 which is below a lid 9 of the pressure vessel is separated by the grid plate 5 from a zone of the pressure vessel containing the fuel assemblies. Support columns 11 protrude from the grid plate, through the plenum 10 up to a top plate 12 above an upper core support 13, to hold the grid plate 5 and the tops of the fuel assemblies. For reasons of clarity, a control-rod guideway 14 is shown above only one fuel assembly. The guideway holds the control rods which can be introduced into control-rod guide tubes of individual fuel assemblies to control the nuclear reaction. The lid therefore bears passages 15 which are assigned to drive elements in each case for a plurality of control rods. Elements 11 and 14 are plenum attachments. The fuel-assembly zone is surrounded laterally by a core shroud 17 inside a core barrel 18, so that the coolant flowing in through an inlet 16 is guided to a flow skirt 19 at the bottom of the pressure vessel. Elements 17, 18, 19 provide a device for deflecting a coolant flow. In each case the coolant then enters the foot of a fuel assembly from below through the lower core support 7, and flows essentially vertically along the fuel rods to passage openings in the top plate which covers the corresponding fuel assembly at the top of the fuel assembly. The coolant then enters the plenum 10 from the respective fuel assembly through the top 3 of the fuel assembly and enters the aperture 4 of the grid plate 5. In the plenum the coolant is deflected to one or more lateral outlet nozzles or an outlet 20. FIG. 2 shows the horizontal components of the coolant flow which occur within a quadrant of the core shroud. In this case, the fuel assemblies are disposed in rows 22 having an alignment which is shown in FIG. 2. In this case, gaps 23 are formed between the individual rows of fuel assemblies, with the coolant being able to pass through the gaps 23 from one row of fuel assemblies to another in a largely unobstructed manner. These transverse flows are produced by pressure differences below the grid plate. The pressure differences occur due to damming-up which the coolant suffers because of obstructions to flow which it encounters in the plenum after it passes through the grid plate and on the path to the outlet. These pressure differences and flows cause bending and horizontal vibrations, above all in the upper region of the fuel assemblies, which can lead to damage to the fuel rods and fuel assemblies that are bent in any case in the course of reactor operation due to the high temperatures, temperature loading and radiation-related changes. In order to be certain that a spacing, which is sufficient for the coolant flow, is always ensured between individual fuel rods of a fuel assembly despite this bending, the fuel rods are guided through apertures of spacers 24 shown in FIG. 1 and mechanically supported at different axial positions. It is already known (from European Patent Application 0 246 962 A1, corresponding to U. S. Pat. No. 4,804,516) to select the axial spacing of the spacer grids to be narrower in the upper region of the fuel assembly. However, ruptures of welds or other mechanical damage may occur even on the spacers. FIG. 2 shows some positions 26 at which turbulences and particular mechanical loads occur, for example due to great changes in the flow and the flow direction. Whereas a controlled transverse flow is desirable per se to increase the thorough mixing and cooling effect and can be produced intentionally by guide surfaces on the spacer webs, such inhomogeneous flow conditions as are shown in FIG. 2 are also undesirable with respect to a uniform cooling of the reactor core. Whereas in boiling-water reactors the coolant flow, which is already distributed relatively uniformly on a lower grid plate or the lower core support 7 over the different regions of the core cross section, is guided individually in the individual fuel assemblies (the feet of the fuel assemblies contain funnel-shaped, laterally closed transition pieces and the bundle of fuel rods is surrounded laterally by a fuel-assembly water canal), the feet of customary pressurized-water fuel assemblies are formed only of a laterally open frame, and the fuel assemblies are not surrounded laterally by a canal. The invention therefore provides for uniform pressure conditions to be enforced in the fuel assemblies of a pres- surized-water reactor by corresponding throttling of the coolant flow when it enters the plenum 10, thus obviating the cause of the above-mentioned transverse flows below the grid plate. FIG. 3 shows a cross section through a top region of a fuel assembly. Upper closure caps 30 of individual fuel rods 31, in which a compensation space is provided through the use of compression springs, for gaseous fission products produced by nuclear operations, are held in the apertures or meshes of a spacer 24. The spacers themselves are supported by control-rod guide tubes 32 which are attached to a top plate 34 by a screwed-on nut 33. A similar attachment is also provided between the guide tubes and the feet 6 of the fuel assemblies, so that the top plate which is supported by a frame 35 of the top of the fuel assembly, the guide tubes with the spacers and the foot part, form a supporting skeleton for the fuel rods. As is also shown in FIG. 5, the frame 35 of the top of the fuel assembly with the associated top plate 34 is supported on the grid plate 5 through the use of compression springs 36. FIG. 4 shows that the top plate 34 has passage openings 40 which are advantageously disposed in such a way that they lie above interstices which are produced between the individual fuel rods 31. In the exemplary embodiments of FIGS. 3 and 5, a throttle plate 41 is releasably attached at least in the top of a plurality of fuel assemblies. The throttle plate can rest, in particular, on the top plate, with the throttle plate 41 being bolted to the top plate 34 through the nut 33 of some control-rod guide tubes 32 in FIG. 3. FIG. 5 shows that the top plate 34 and the throttle plate 41 are advantageously held through common holding-down devices, for example the springs 36, in the top of the fuel assembly. According to FIG. 4, the throttle plate contains throttle openings 43 which advantageously have, in total, a smaller cross-sectional area than the passage openings 40 in the top plate 34 and lie with the largest part of their cross-sectional area above the passage openings 40. The configuration of the individual throttle plates and the dimensioning of their passage openings are adapted individually to the position of the respective fuel assembly on the grid plate in such a way that, when the coolant passes through the tops of all of the fuel assemblies, for example, a uniform damming-up is produced everywhere, that is to say no horizontal changes in pressure occur. In this case, however, provision may also be made by appropriate construction of the throttle plates to maintain a particular uniform pattern of weak transverse flows to increase thorough mixing of the coolant. FIG. 6 shows that the underside of the grid plate 5 can carry fuel assembly alignment pins 60 which engage in corresponding bores in the top parts 3 of the fuel assemblies in order to position the tops of the fuel assemblies at the respective apertures in the grid plate 5. The upper surface of the grid plate 5 carries the control-rod guideways 14, the support columns 11 and holding structures 11' for the tops of the fuel assemblies. Webs of the grid plate 5 form individual apertures, with throttle elements 61 being inserted in at least a plurality of the apertures. During an exchange of used fuel assemblies, the throttle elements can be inserted together with new fuel assemblies in order to adapt the pressure in the coolant, which emerges from the top of the new fuel assemblies supported on the grid apertures, to the pressure which prevailed in the old fuel assembly. If, in the case of such a fuel-assembly exchange, fuel assemblies which have not yet been burnt out completely are transferred to a different site in the reactor core, the throttle elements which are advantageously constructed as inserts for the grid apertures, can again be placed at the old site. The throttle plates or throttle elements according to the invention thus influence the damming-up occurring in the coolant below the grid plate in such a way that virtually no horizontal pressure differences occur below the grid plate or at least these pressure differences lead to a desirable distribution of the coolant when it enters the plenum. Additionally, they can contribute to the stabilizing of the desired flow, as a result of which even the thermodynamic and hydrodynamic conditions in the reactor core can be calculated and controlled in a simpler manner.
	abstract	A method including directing a first electrical signal to at least one of a plurality of probes each positioned within a chamber of a charged particle beam device. At least one of the plurality of probes is exposed to a charged particle beam of the charged particle beam device, and a second electrical signal is compared to the first electrical signal to determine a characteristic associated with the at least one of the plurality of probes.
	description
	description	The present application is a national phase entry under 35 U.S.C. § 371 of International Application No. PCT/EP2016/071788 filed Sep. 15, 2016, published in French, which claims priority from French Patent Application No. 1558823 filed Sep. 18, 2015, all of which are incorporated herein by reference. The invention relates to a belt for measuring physical quantities such as for example temperature, level, heat flow, of an object. One field of application of the invention relates in particular to water pipes such as for example those of the primary circuit of nuclear power plants. Such a belt for measuring temperature is known for example from U.S. Pat. No. 4,553,432. In this known belt, a temperature monitoring electric wire is attached to the belt by a clamping block situated in a groove of a thermal insulation surrounding the pipe. This known belt is used to measure the temperature and the humidity around steam pipes, so as to detect leakage there, or in a drain of a nuclear power plant to detect that the water falling into this drain comes from a leak, so as to be used as a surveillance system for it. One of the disadvantages of this known belt is that the temperature sensor is not applied directly against the pipe, of which the temperature must be measured, but rather a layer of thermal insulation is provided between the temperature sensor and the pipe. Now, in order to have a reliable temperature measurement, it is desired to have satisfactory contact between the temperature sensor and the object. In particular, the invention must be able to be used in certain constraining environments, such for example as those having reduced space, high temperature, ionizing radiation, such as for example on water pipes of pressurized-water reactors (abbreviated PWRs) of electricity production power plants. These environments are subjected to supplementary qualification requirements of the measurement belt, which can for example be resistance to earthquakes, resistance to pressure, resistance to high temperatures, resistance to humidity, resistance to high mechanical constraints. In addition, in the case of an environment subjected to ionizing radiation, as for example for a water pipe of a pressurized-water nuclear reactors, the persons who must install the measurement belt on the pipe are exposed to this radiation. It follows not only that the staff must intervene very rapidly to minimize the quantity of radiation received during the intervention but must also have a measurement belt that is reliable, systematic and able to adapt to any type of object on which it must be installed. Thus, the measurement belt must for example be able to be installed on an object which may have a mean temperature of 300° C. in the case of a pipe of an electricity production power plant in operation, and 70° C. when stopped. In the case of a water pipe of a nuclear reactor of an electricity production power plant, subjected to ionizing radiation, the irradiation in the assembly zone of the belt can attain 5 kGy/year (or 100000 Gy in 20 years) at full power. Thus, these environments must not be penalizing factors on the assembly time and the good positioning of the attachment belt on the object. In the case of a water pipe of a nuclear reactor of an electricity production power plant, thermocouples placed directly in contact with the zone to be studied to measure temperature are known. Thermocouples being directly welded to piping is known, creating surface constraint zones. At the conclusion of instrumentation, it was necessary to grind the surface on the thickness impacted by the constraint zone so as to avoid any risk of later cracking. This solution can respond partially to the problem of dynamic behavior but is shown to be very penalizing in terms of dosimetry because the time required for installation and proper positioning of the sensor and the reconditioning of the piping at the conclusion of the measurement campaign is high. But much of the piping is not accessible to this type of implementation. In the case of thermal fatigue measurement, a large number of sensors (8 to 20 for sections of 5 to 40.6 cm) must be placed according to a predefined distribution depending on the phenomena expected on the same circumference of the piping. The layout, and even more the welding in place of each sensor individually on the piping is difficult and sometimes even impossible due to the presence of supports and obstacles not allowing a welder to operate in a reasonable time. This problem returns during the removal of the instrumentation, during which it is necessary to manage the effluents due to the grinding of the piping. This type of instrumentation is accompanied by a very complex technical file and administrative authorizations that are difficult to obtain. In addition, the implementation of positioning and attachment systems of sensors to the piping grouped within the same device generally has problems of heat conduction between sensors and piping and of common modes between sensors. Thus, the invention aims to obtain a belt for the measurement of physical quantities of an object that mitigates the disadvantages of the prior art and responds to the requirements of these constraining environments and remains reliable in them by requiring a very short intervention time of the staff for assembling the belt to the object in these environments. To this end, the invention provides a belt for measuring an object, the belt comprising: at least one measurement sensor, a strip having a circumference intended to surround the object, a device for clamping the strip around the object, characterized in that the belt further comprises a pressing device for pressing the measurement sensor in a first orientation of a first direction directed toward the object, the pressing device comprising at least one casing attached to the strip (10), at least one intermediate part housed in the casing, and at least one constraining member inserted between the casing and the intermediate part and capable of having the intermediate part assume a first low position in which it presses toward the sensor in the first orientation of the first direction toward the object, the pressing device of the sensor further comprises a lifting member, for holding the intermediate part in a second lifting position above the first low position in a second orientation of the first direction, opposite the first orientation against the constraining member, the lifting member being actuable from the outside of the casing to have the intermediate part pass from the second lifting position to the first low position in which it presses toward the sensor. Thanks to the invention, it is possible to immobilize the sensor with rapidity and reliability against the object in environments constraining to the staff. Thus, the direct assembly of the sensor against the object can be systematized with great rapidity in constraining environments such as those mentioned above and requiring great rapidity of intervention by the staff. Thanks to the invention, the sensor can be applied directly against the object by the pressing device. In addition, the second lifting position allows first positioning the belt around the object, so as to not yet exert pressure on the sensor, then, passing from the second lifting position to the first low position, pressing the sensor against the object. Thus, the installation of the belt, due to the fact that it is accomplished with the second lifting position of the pressing device, is not interfered with by the pressing of the sensor against the object, which is carried out only later, once the belt is positioned and attached to the object, when the pressing device passes from the second lifting position to the first low position guaranteeing optimal coupling of the sensor. This also allows not damaging the sensors during the installation of the belt. According to one embodiment of the invention, the lifting member passes through a first guide provided in the intermediate part and abuts against an abutment of the casing in the second lifting position, the lifting member being capable of being removed from the first guide of the intermediate part to have the intermediate part pass from the second lifting position to the first low position in which it presses toward the sensor. According to one embodiment of the invention, the first guide comprises in the intermediate part a hole for letting through the lifting member in the intermediate part during its passage into the second lifting position. According to one embodiment of the invention, the lifting member comprises a wire having at least one end section situated outside the casing to allow the lifting member to be removed. According to one embodiment of the invention, the measurement sensor is a temperature sensor. According to one embodiment of the invention, a plurality of measurement sensors distributed along the circumference of the strip is provided as a measurement sensor, the plurality of measurement sensors being associated with a plurality of respective pressing devices having a plurality of lifting members. According to one embodiment of the invention, the lifting members are mutually integral. According to one embodiment of the invention, the lifting members are formed by the same wire having at least one end section situated outside the casings to allow the lifting members to be removed. According to one embodiment of the invention, the constraining member comprises a first spring inserted between the casing and the intermediate part. According to one embodiment of the invention, at least one heat-insulating layer is provided between the intermediate part and the measurement sensor. According to one embodiment of the invention, the device for clamping the strip around the object comprises: at least one first hooking part attached in proximity to a first end of the strip and at least one second hooking part attached in proximity to a second end of the strip, a first module for connection to the hooking parts, capable of being mounted removably on them, the first module comprising a first spindle for driving the first hooking part in a first joining direction coming closer to the second hooking part and a second spindle for driving the second hooking part in a second joining direction coming closer to the first hooking part, at least one second guide on which the first and second spindles are slidably mounted respectively in the first and second joining directions, and at least one second bias spring mounted between at least one of the spindles and the second guide to cause the spindles to come closer one to another in the first and/or second joining direction, a second approximation module for bringing the spindles closer in the first and second directions, allowing the immobilization of the spindles in a clamping position of the belt around the object. According to one embodiment of the invention, the second approximation module comprises a gripper for gripping the spindles. According to one embodiment of the invention, the second approximation module comprises at least one first jaw for gripping the first spindle and at least one second jaw for gripping the second spindle, the first jaw being integral with at least one first arm, the second jaw being integral with at least one second arm, the first arm being hinged with respect to the second arm by a main axis of rotation situated at a distance from the jaws, the second approximation module further comprising at least one screw cooperating with the arms to cause the jaws to come closer one to another by rotation around the main axis. According to one embodiment of the invention, the approximation module is of the parallelogram or pantograph type between the screw and the jaws. According to one embodiment of the invention, the second approximation module comprises at least one first connecting rod having a first hinge axis with respect to the first arm between the main axis and the first jaw, at least one second connecting rod having a second hinge axis with respect to the second arm between the main axis and the second jaw, the connecting rods being mutually hinged by a third axis situated at a distance from the first and second axes, the screw cooperating with a first support mounted on the main axis and with a second support mounted on the third axis to allow the jaws to come closer one to another by moving the first and second supports away one from another. In the figures, the measurement belt 1 according to the invention is used to attach at least one sensor 5 against an object OBJ. This object OBJ can for example be a fluid pipe OBJ, such as for example a water pipe, as is described below. One case of application of the invention is a belt 1 for mechanical attachment of one or more measurement sensor(s) 5 on a liquid or gas pipe as the object OBJ. The object OBJ is for example a water pipe of the primary circuit of a pressurized-water nuclear reactor (PWR) of an electricity production power plant. The water pipe can be high-pressure piping. Of course, the belt 1 can comprise one or more sensors 5 such as one or more temperature sensors, level sensors, heat flow sensors or any other measurement sensor for a physical quantity. These sensors 5 can be temperature sensors (thermocouples, platinum probe, for example) but also other types of sensors (level measurement, heat flow for example). Different types of sensors can cohabit on the same belt and be implemented simultaneously. The belt 1 comprises a strip 10 having a circumference intended to surround the object OBJ, such as for example the pipe OBJ. In the figures, the object OBJ extends in an axial direction X, around which the belt 1 must be disposed. Consequently, the strip 10 of the belt 1 surrounds the object OBJ in a plane transverse to the direction X, this transverse plane being formed by the directions Z and Y, mutually perpendicular and perpendicular to the direction X. The direction Z originates from the axis X of the object OBJ to pass through the object OBJ toward the belt 1 intended to surround the object OBJ around this axis X. The direction Y is the direction tangent to the circumference of the strip 10 around the object OBJ and around the axis X. The strip 10 is a strip made of metal for example. The object OBJ or the pipe OBJ has for example an outer cylindrical contour, circular for example. For example, in the case of a circular cylindrical object OBJ around the axis X, the direction Z is the radial centrifugal direction, starting with the object OBJ, from the inside to the outside with respect to the belt 1. The object OBJ or the pipe OBJ can have a metallic outer surface, made of steel for example, against which the belt 1 is disposed. Of course, the invention can apply to any type of object, particularly cylindrical around the direction X which must be surrounded by the belt 1, which can be other than those mentioned above such as for example thermodynamic systems, agri-food, petrochemistry, methanation units. The belt 1 comprises at least one sensor 5. According to one embodiment, the belt 1 comprises at least one temperature sensor 5. For example, in FIG. 1, a plurality of temperature sensors 5 is provided in the belt 1. The temperature sensor(s) 5 are mounted below the strip 10 and therefore at a distance from the strip 10. According to one embodiment, at least one lower heat insulating layer 6 is provided between the strip 10 and the temperature sensor(s) 5. This heat insulating layer 6 is for example attached below the strip 10, below its inner side 109 turned toward the object OBJ, along its circumference intended to surround the object OBJ along the tangential direction Y. The temperature sensor 5 or each of the temperature sensors 5 comprises for example a thermocouple 500. The sensors 5 are for example at equal distance, one following the other, below the strip 10. For example, different types of sensors, i.e. sensors measuring different physical quantities, can cohabit on a same single belt and be implemented simultaneously. The belt 1 further comprises a device 8 for clamping the strip 10 around the object OBJ. The clamping device 8 allows for example hooking the strip 10 around the object OBJ. According to one embodiment, the sensor 5 is a part of a measurement chain. FIG. 1 represents these elements as well as the interfaces between the measurement chain and the outer elements. A first interface is for example formed by the outer surface SUR of the object OBJ, against which the sensor 5 must be attached by the belt 1. The sensor 5 serves to transform the physical quantity G or measured G into an exploitable (often electric) signal S. The conditioner COND converts the quantity S at the output of the sensor 5 into a voltage whose amplitude or frequency reflects the temporal evolution of the physical quantity G. The first interface SUR constitutes the border between the physical process and the information desired. The capacity of the sensor 5 to measure the physical quantity can be penalized by elements belonging to the environment (corrosion, geometric irregularities, humidity, etc.) and particularly for sensors in direct contact. In certain applications (ex. measurements by fastening on piping) there exists another indispensable element for proper operation of the instrumentation chain. This is the mechanical attachment system 1 of the sensor 5 which has as its main role to support and hold the sensor 5 in contact with the component which it is desired to measure, most often piping, allowing the chain to continue to provide the function expected: measurement of the physical quantity. To guarantee the proper operation of the sensor 5, the attachment system 1 must also insulate it from any perturbation inherent in the process but not desirable for measurement (ex. vibration, thermal and mechanical constraints, etc.). In the case of a pressurized-water reactor (PWR), a strict observance of the objectives of quality to be attained is indispensable. Such is the case in particular with mechanical equipment resisting pressure (primary, secondary and auxiliary circuits) for which the Design and Construction Rules (DCR-M for mechanical equipment) have been defined. For any mechanical equipment not subjected to the DCR, such as for example the system 1 for attaching the sensor 5, a qualification process must be implemented to guarantee the metrological performance of the instrumentation chains (functional qualification). Regarding the mechanical attachment system 1, there does not exist any dedicated design and manufacturing standards, but qualification tests must verify their safety with respect to the component on which it will be installed. During qualification, conditions such as resistance to earthquakes, pressure, temperature or humidity can be verified. In addition to the conditions required during qualification, other particular conditions of the primary circuit of a PWR must be considered when such attachment systems 1 are installed there permanently: A mean temperature of 300° C. in operation and less than 70° C. during a unit outage. An irradiation of 5 kGy/y (or 100000 Gy in 20 years) at full power. The first condition above has an impact on the selection of the material and on the design of the attachment system 1. The system 1 for attaching the sensor 5 must be designed to resist strong mechanical constraints while still holding its main function. As for the second condition, it plays an implicit role in the selection of the material but the main impact of the irradiation on the design of the system 1 for attaching the sensor 5 is the intervention time necessary for the installation of the attachment system 1, or for any maintenance operation of the sensor 5 or the attachment system 1 itself. One application case of the invention is a mechanical attachment belt 1 of a temperature sensor 5 against a water pipe OBJ of the primary circuit of a nuclear pressurized-water reactor of an electricity production power plant. According to the invention, the belt 1 comprises a pressing device 50 for pressing the temperature sensor 5 in a first orientation 55 of a first direction directed toward the object OBJ. The pressing device 50 comprises at least one casing 53 attached to the strip 10. The temperature sensor 5 is situated below the strip 10. The casing 53 is situated on the strip 10. The pressing device 50 further comprises at least one intermediate part 52 (or tappet 52) housed in the casing 53, and at least one constraining member 51 inserted between the casing 53 and the intermediate part 52. The intermediate part 52 serves to ensure coupling of the temperature sensor 5 against the object OBJ or the pipe OBJ or the piping OBJ. The constraining member 51 is capable of having the intermediate part 52 assume a first low position in which the intermediate part 52 presses toward the sensor 5 in the first orientation 55 directed toward the object OBJ. For example, as shown in FIG. 2, the strip 10 comprises one or more holes 101 allowing the passage of the intermediate part(s) 52 through the strip 10 in the orientation 55. The casing(s) 53 are each attached to the edges of the corresponding hole 101, for example by welding. In order to avoid or reduce direct conduction from a temperature sensor 5 site to another, which could perturb measurement, the strip 10 has cutouts 102, rectangular for example, situated between the holes 101. The casing 53 has for example a lateral cylindrical, for example circular, surface around the guiding orientation 55, the intermediate part 52 also being cylindrical, for example circular, against and inside the casing 53. The casing 53 is for example a perforated cylinder. In the figures, the orientation 55 directed toward the object OBJ is for example in the opposite orientation to the direction Z. For example, in the case of a circular cylindrical object OBJ around the axis X, the first orientation 55 is in this case the radial centripetal direction. The pressing device 50 further comprises a lifting member 54 for holding the intermediate part 52 in a second lifting position situated above the first low position in a second orientation 56 of the first direction, which is opposite the first orientation 55 and which is against the constraining member 51. This second orientation 56 corresponds for example, in the case of a circular cylindrical object OBJ, to the centrifugal radial direction parallel to the direction Z and in the same orientation as that. The lifting member 54 is actuable from the outside of the casing 53 to have the intermediate part 52 pass from the second lifting position to the first low position in which the intermediate part 52 presses toward the sensor 5. The belt 1 takes into account constraints linked to the nuclear environment (ionizing radiation) as well as all the other constraints belonging to an industrial facility such as bulk, compatibility of materials, mechanical resistance of the system to earthquakes. The measurement belt 1 according to the invention offers the advantage of being able to install a large number of measurement sensors 5 which can be of different natures, i.e. capable of measuring different physical quantities, in a very rapid manner around an object OBJ, which is particularly attractive in the case where this object OBJ is situated in a constraining environment, such as, for example, for nuclear applications where response time is very limited, as in the containment building of a nuclear reactor subjected to ionizing radiation, for which the operators must intervene in the shortest time possible to be subjected to as little as possible of this radiation. The invention thus allows installation, with high reliability, of a large number of sensors 5, of temperature for example, in these constraining environments. The invention allows the sensor(s) 5 to be put into contact, with good coupling, directly with the object OBJ, which allows the accuracy of the measurement(s) to be optimized, and to reduce their response time. In FIGS. 3 and 4, the intermediate part 52 or its portion 521, designed for temperature sensors, is for example in the form of a supporting pin. The intermediate part 52 comprises a lower base 521, for example a circular cylinder around the pressing orientation 55. The lower base 521 is situated on the side of the sensor 5 and is attached on its outer side to a rod 522 extending beyond the top of the casing 53 in the orientation 56. The constraining member 51 comprises for example a first spring 510 inserted between the casing 53 and the intermediate part 52. For example, the first spring 510 is housed in the casing 53. The spring 510 is for example a compression spring fitted around the rod 522 against the base 521 to push this base 521 in the first orientation 55 toward the temperature sensor 5. According to one embodiment, the lifting member 54 passes through a first guide 520 provided in the intermediate part 52 and abuts against an abutment 530 of the casing 53 in the second lifting position. The lifting member 54 is capable of being removed from the first guide 520 of the intermediate part 52 to lower the intermediate part 52 from the second position to the first position pressing toward the sensor 5. The abutment 530 is for example formed by an outer wall of the casing 53, distant from the sensor 5. According to one embodiment, the first guide 520 is formed by a hole 520 provided in the intermediate part 52, so that the lifting member 54 passes through the intermediate part 52 in the second position. The hole 520 is provided for example in the outer portion of the rod 522, situated outside the casing 53 in the second lifting position. For example, the lifting member 54 comprises or is formed by a wire 540 having one or two end sections 541 situated outside the casing 53 to allow the removal of the lifting member 54. The wire 540 is metallic for example and can be made of stainless steel. As shown in FIG. 1, a plurality of temperature sensors 5 distributed along the circumference 108 of the strip 10, to be distributed around the object OBJ, is for example provided as a sensor 5. A plurality of associated respective pressing devices 50 is provided for the plurality of temperature sensors 5, such as that described above. The temperature sensor(s) 5 are each connected to an outer cable 501, which extends under the strip 10 and which extends beyond it to be accessible from the outside and to be able to be connected to an external acquisition and processing unit for the measurements carried out by the sensor 5 (for example the conditioner COND and/or others). The pressing devices 50 are for example at equal distances, one following the other, on the strip 10. The respective lifting members 54 of the pressing devices 50 are for example mutually integrated. According to one embodiment, the lifting members 54 are formed by the same wire 540 having one or two end sections 541 situated outside the casing 53 to allow the lifting members 54 to be removed. Thus, during a first installation step of the belt 1 around the object OBJ, the pressing devices 50 are first pre-positioned in the second lifting position of the intermediate part 52. The strip 10 is disposed around the object OBJ, such as for example a circular cylinder pipe OBJ. Using the clamping device, the strip 10 is attached around the object OBJ in a position of immobilization. Then, during a second step, the pressing device(s) 50 are made to pass from the second lifting position to the first low position by removing the lifting member 54, for example by pulling on the wire 540 to remove the latter. The constraining member 51 then displaces the intermediate part 52 in the first orientation 55 toward the temperature sensor 5 and toward the object OBJ, which holds the temperature sensor 5 between the intermediate part 52 and the object OBJ. Thus, the lifting member 50 prevents applying pressure to the temperature sensor 5 when the strip 10 is displaced with respect to the object OBJ during the first installation step, and thus prevents damaging it. According to one embodiment, the at least one lower heat-insulating layer 6 is provided between the intermediate part 52 and the temperature sensor 5. Another external heat-insulating layer 7 can be attached over all or a portion of the outer surface 110 of the strip 10, far from the object OBJ. The outer heat-insulating layer 7 can cover the pressing device(s) 50, comprising the layer 532. The heat-insulating layer 6 and/or 7 and/or 532 has a thermal conductivity less than that of the strip 10 and/or that of the object OBJ or that of steel. For example, the heat-insulating layer 6 and/or 7 and/or 532 is made of a material having a thermal conductivity less than or equal to 0.5 W/mK at 300° C. According to one embodiment, the material of the heat-insulating layer 6 and/or 7 and/or 532 does not contain halogens, so as to be appropriate in use in a nuclear environment (PWR or other), as mentioned above. A foldable heat-insulating flap 800, for example made of canvas, attached to one side of the clamping device 8, can be provided to cover the clamping device 8 in its immobilization position. For example, the heat-insulating layer 6 and/or 7 and/or 532 is made of glass cloth. The lower heat-insulating layer 6, in permanent contact with the object OBJ, avoids any formation of an air gap between the belt 1 and the object OBJ. In the case of thermocouples 500, the sensors 5, put into contact individually and insulated by the glass cloth 6, have a rapid response time and good measurement accuracy, the effects of common mode being limited thanks to the design of the metal ribbon 10. According to one embodiment, the thermocouple 500 of the temperature sensor 5 is attached, for example using ligature(s) 502, under the lower heat-insulating layer 6, and for example also with the outer heat-insulating layer 7 on the strip 10. Thus, the temperature sensor 5 or the thermocouple 500 is in contact with the object OBJ in the second low position of the pressing device 50 without being in direct contact with the strip 10; thermal drains caused by the belt are thus limited. The thermocouple 500 has for example a diameter of less than 5 mm, and is for example 1 mm. One or more ligature(s) 503 can also be provided to attach the outer heat-insulating layer 7 to the strip 10, for example with the lower heat-insulating layer 6, at places other than those where the temperature sensor 5 or thermocouple 500 are located. The casing 53 can also be covered by a heat-insulating layer 532, nevertheless having a passage for the intermediate part 52 and/or the rod 522 and/or the lifting member 54. The strip 10 is for example metallic, in the form of a ribbon, made for example of stainless steel sheet. The metal ribbon 10 is used to surround the pipe to guarantee solid attachment of the other elements of the system. The length of the strip 10 can be cut to be adapted to the circumference of the object OBJ or the pipe OBJ. The strip 10 is configured to tolerate variations in temperature (and therefore the mechanical constraints) belonging for example to high-pressure piping OBJ (for example the primary circuit of a pressurized-water reactor). The configuration of the strip 10 can be adapted to the instrumentation of elbows; in this case, the closure by the clamping device 10 will be positioned on the neutral fiber of the elbow. According to one embodiment shown in FIG. 16, the strip 10 has a second end 104 narrower in the axial direction X than its other first end. The second end 104 slips under two metal guides 1031 and 1032 welded to the transverse edges of the other lower first end 103 of the strip 10. Described below are the embodiments of the clamping device 8 of the strip 10 around the object OBJ, with reference to FIGS. 5 to 14. In FIGS. 5 to 9, the clamping device 8 of the strip 10 comprises at least one first hooking part 11, attached (by welding for example) in proximity to a first end 103 of the strip and for example two hooking parts 12 distant from one another in the axial direction X. The clamping device 8 of the strip 10 also comprises at least one second hooking part 12 attached (by welding for example) in proximity to the second end 104 of the strip 10, for example two hooking parts 12 distant from one another in the axial direction X. A first module 3 for connection to the hooking parts 11, 12 is capable of being mounted removably on them. The hooking parts 11, 12 have at least one protruding hook 111, 121, for example V-shaped, the hooks 111, 121 extending away from one another in the opposite orientation of one another in the direction Y. The parts 11, 12 or hooks 111, 121 each have a recess 112, 122 for receiving spindles, respectively 21 and 22. The hooking parts 11, 12 can be welded upon request depending on the geometry of the belt which depends on the diameter of the object OBJ. The hooking parts 11, 12 allow a solid assembly between the strip 10 and the object OBJ during the first installation step, to then allow the attachment of the approximation module 200. The first module 3 comprises a first spindle 21 for driving the first hooking part 11 in a first joining direction directed toward the second hooking part 12 and a second spindle 22 driving the second hooking part 12 in a second joining direction directed toward the first hooking part 11. The connecting module 3 comprises a second guide 30 on which the first and second spindles 21, 22 are slidably mounted respectively in the first and second joining direction(s), and at least one second bias spring 40 mounted between at least one of the spindles 21, 22 and the second guide 30 to cause the spindles 21, 22 to come closer one to another in the first and/or second joining direction(s). The first and second joining directions are therefore substantially parallel to the direction Y in the figures, i.e. the direction tangent to the circumference 108 of the strip 10 around the object OBJ and around the axis X. The guide 30 is for example adjustable. The spring 40 is for example a tension spring in FIG. 5, while in the example of FIG. 9, the spring 40 is a compression spring. At least one bias spring 40 mounted between the spindle 21 and the guide 30, and at least another spring 40 mounted between the spindle 22 and the guide 30 are for example provided. The guide 30 comprises for example a first guide portion 31, on which a first portion 211 of the first spindle 21 is slidably mounted and on which a first portion 221 of the second spindle 22 is slidably mounted, as well as a second guide portion 32 on which a second portion 212 of the first spindle 21 is slidably mounted and a second portion 222 of the second spindle 22 is slidably mounted. The guide 30 or each guide portion 31, 32 is for example in the shape of a stirrup having, on the one hand a first section 33 for guiding of the first spindle 21, and on the other hand a second section for guiding 34 of the second spindle 22. The sections 33, 34 are connected to a core 35 situated between them in the first and/or second joining direction. To install the connecting module 3, the first spindle 21 is passed behind the hooking part(s) 11 against the force of the spring(s) 40 and the spindle 22 is passed behind the hooking part 12 against the force of the spring(s) 40 acting on this spindle 22. According to the embodiment shown in FIG. 17, the guide 30 can comprise one or more stop holes 301 in which are placed one or more other wires 302 (for example metal wires) for holding the spindle 21 (or portion 211 or 212) and/or 22 (or portion 221 or 222) against the force exerted by the spring 40, in a position spreading the spindles 21 and 22 with respect to the hooking parts 11, 12. This thus allows fitting the spindles 21 and 22 around the hooking parts 11, 12. It is then sufficient to withdraw the wire(s) 302 to release the spring 40 which then displaces the spindle 21 and/or 22 against the hooking parts 11, 12 to clamp them. The connecting module 3 provides elastic holding on the object OBJ so as to resist differential dilations and to vibrations. The connecting module 3 may not have been designed to withstand the intense mechanical forces exerted in particular during the application of pressure to the sensors 5. The connecting module 3 makes it possible to ensure the holding of the belt 1 over the entire dimensional range of the standard. The module 3 makes it possible to pre-position the belt 1 around the object OBJ in order to, firstly, close the belt 1 around the object OBJ during the first step. The spring(s) 40 allow pre-constraining the first module 3 in a position connecting the hooking parts 11, 12 together, so as to close the strip 10 around the object OBJ. The measurement belt 1 allows the simultaneous implementation of a large quantity of measurement points in a few minutes while still guaranteeing their geometric position. Manufactured for one diameter of piping, it can be positioned without adjustment over the entire range of the standard. The positioning of the sensors 5, but also of the exit of the cables of the sensors 5 during manufacture allows, in application of the implementation procedure, a guarantee against any error in positioning and any ambiguity in benchmarking. The recommendations which are made there regarding packaging allow the risks of radiological or chemical surface contamination to be limited. The belt 1 allows accomplishing measurements on piping OBJ with small diameters with a large density of measurement points by mixing, as needed, the types of sensors and being able to accomplish measurements in elbows and over all diameters. The measurement belt 1 is compact and easily adaptable to the specific needs of its use. Its range of applicability extends from 1.5 inches to several hundred inches. In the case of large diameters of the object OBJ, the recourse to several sections of strip 10, connected to one another, allows guaranteeing good holding of the belt 1 at all points of the circumference, the positioning devices allowing the observance of the spacing provided between each section. A particular design allows its use in elbows. Despite that, the sensors 5 and the thermocouples 500 remain identical, they can be mixed on the same belt. With a very small thickness, the belt 1 has been designed for rapid installation (less than 2 minutes per belt) and for low bulk; it can be used up to 400° C. and be covered by a mattress thermal insulator without particular specification (for example for nuclear applications). The measurement belt 1 having a very small thickness, it does not require a specific design of a thermal insulator and can be covered by a standard mattress thermal insulator. The belt can carry one or more sensors 5, the possible density of the sensors 5 depending to a large extent on the volume of the sensor itself and on the bulk of the device 50 for applying pressure. In the case of thermocouples, this density can be very large (up to 1 sensor for every 15 mm of the circumference of the strip 10), a density which can be doubled by placing the sensors 5 offset both in the axial direction X and in the tangential direction Y, with the same offset for the pressing devices 50 situated above the sensors 5, for example in alternating pitch as shown in FIG. 6 for the sensors and the pressing devices 50. The belt 1, very light, being attached elastically on the object OBJ or the piping OBJ, and each sensor 5 having an individual pressing system, the belt 1 guarantees good contact between the sensor and the piping, independently of variations in temperature (causing dilation and therefore mechanical constraints), vibrations or clamping torque on the object OBJ or the piping OBJ. It has perfect safety with regard to the facility in which the object OBJ is located or the fluid circuit in which the piping or pipe OBJ is located. The clamping device 8 further comprises a second approximation module 200 for the spindles 21, 22 in the first and second directions, allowing the immobilization of the spindles 21, 22 in a clamping position of the belt 1 around the object OBJ. This approximation module 200 comprises for example a gripper for gripping the spindles 21, 22 as shown in FIGS. 9 to 14. According to one embodiment, the second approximation module 200 comprises a first jaw 201 for gripping the first spindle 21 and a second jaw 202 for gripping the second spindle 22. The first jaw 201 is integral with a first arm 211, while the second jaw 202 is integral with a second arm 212. The first arm 211 is hinged with respect to the second arm 212 by a main axis of rotation 203, which is situated at a distance from the jaws 201, 202. The second approximation module 200 further comprises at least one screw 204 cooperating with the arms 211 and 212 to cause the jaws 201, 202 to come nearer one to another by rotation of the arms 211, 212 around the main axis 203. According to one embodiment, the approximation module 200 is of the parallelogram or pantograph type between the screw 204 and the jaws 201 and 202. Thus, according to one embodiment, the approximation module 200 comprises a first connecting rod 205 having a first hinge axis 207 with respect to the first arm 211, this hinge axis 207 being situated between the main axis 203 and the first jaw 201. In addition, the second approximation module 200 comprises a second connecting rod 206 having a second hinge axis 208 with respect to the second arm 212, this hinge axis 208 being situated between the main axis 203 and the second jaw 202. The connecting rods 205 and 206 are hinged to one another by a third hinge axis 209, which is situated at a distance from the axes 207 and 208. The screw 204 cooperates with a first support 231 mounted on the main axis 203 and with a second support 232 mounted on the third axis 209 to allow the jaws 201, 202 to come closer one to another by moving the first and second supports 231 and 232 away from one another. For example, the connecting rod 205 is parallel to the arm 212, while the connecting rod 206 is parallel to the arm 211. Two first jaws 201 are provided for example of respectively two first arms 211, which are situated at a distance from one another in the axial direction X surrounded by the belt 1 and/or two second jaws 202 of respectively two second arms 212 situated at a distance from one another in the axial direction X surrounded by the belt 1. For example, the lower end 2041 of the screw 204 is mounted freely in the lower support 232, while, between its lower end 2041 and its upper head 2042, the screw 204 comprises a thread 2043 inserted in a corresponding internal screw thread 2044 of the upper support 231 to, by rotation of the head 2042, cause the support 231 to come closer to and move away from the support 232 by rotation of the head 2042 in one direction or in the other. For this purpose, the head 2042 can be attached to a thumbwheel 2043 for manual gripping of the screw 204. Thus, the rotation of the screw 204 in one direction causes the approximation of the arms 211 and 212 against the spindles 21 and 22, which allows the spindles 21 and 22 to be clamped to one another and therefore to clamp to one another the hooking parts 11 and 12 of the strip 10. Due to the jaws 201 and 202, this clamping is accomplished with great force and allows the belt 1 to be cramped in a position of immobilization against the object OBJ. This clamping by bringing the jaws 201 and 202 closer one to another is therefore accomplished because the module 3 was previously mounted on the parts 11 and 12, beyond the clamping procured by the connecting module 3 of the spindles 21 and 22. When the clamping device 8 is in the position for immobilizing the strip 10 around the object OBJ, during the second step the lifting member 54 is actuated to have the intermediate part(s) 52 pass from the second lifting position to the first low position pressing toward the sensor 5, which presses and immobilizes the sensor(s) 5 toward the object OBJ. To remove the belt 1 from the object OBJ, the clamping device 8 is actuated, namely, in the example described above, the screw 200 is actuated to move the arms 211, 212 away from one another in order to move the jaws 201 and 202 away from the spindles 21 and 22, as shown in FIG. 11, for example at least to an opening angle of 140° between the arms 211 and 212. Then the connecting module 3 is removed with respect to the hooking parts 11 and 12. As shown in FIGS. 10 and 14, the approximation module 200 offers the advantage of being able to adapt to strips 10 of different circumference lengths 108 between their hooking parts 11 and 12, FIG. 14 thus showing the strip 10 with a length smaller than that of FIG. 10. The clamping device 8 offers the advantage of being adaptable to a large range of object diameters and belt lengths and to all cylindrical objects: piping, pressurizers, steam generators, reactors, exchangers, water pipes. Non elastic, it allows the accurate positioning of the belt 1 and is designed to tolerate intense mechanical constraints, particularly during the application of pressure to the sensors 5. It ensures the immobility of the belt 1 during the installation of the clamping device (second step) or during its withdrawal during dismantling of the instrumentation. In the case of devices comprising several belts 1 connected to one another to girdle a large diameter or a complex shape, it is the clamping devices 8 which will allow good positioning of each belt 1 to be ensured and will provide for their firm holding. The belt 1 allows the simultaneous implementation of several types of sensors on the same single belt 1. Their positioning, accomplished on demand during manufacture, allows them to be adapted to actual needs. The installation of the belt 1 is very rapid and the implementation of the sensors 5 being carried out individually when the belt is firmly tied to the piping, can be adapted specifically to each type of sensor. The dismantling-reassembly of the belt 1 during maintenance shutdowns of facilities, during radiography operations particularly, is rapid and the reconditioning of the pressing devices 50 of the sensors 5 is easy.
047056630	summary	The invention relates to a nuclear reactor fuel element with mutually parallel rods, particularly fuel rods containing nuclear fuel, and a rectangular, grid-shaped spacer with grid mesh openings respectively receiving rods, including outer webs crossing and flatly facing the rods at right angles to the rods, the spacer having an outward curve formed from two outer webs on an outer corner of a corner grid mesh opening located between the two outer webs, being curved in a direction parallel to the longitudinal direction of the rods. A nuclear reactor fuel elelemnt of this type is known from French Patent of Addition No. 91 358 corresponding to U.S. application Ser. No. 482,792 and British Pat. No. 1,153,743. This conventional nuclear reactor fuel element is particularly intended for a boiling water nuclear reactor. The device includes a so-called duct tube formed of sheet metal which is pushed over the nuclear reactor fuel element with spacers and which rests with two sheet metal cross strips on the inside of the corners of the upper end of the fuel element, on two stay bolts on the top of a grid plate belonging to the fuel element head. The sheet metal cross strips are respectively screwed to the stay bolts with a screw penetrating the corss strips. The spacers of this nuclear reactor fuel element have outer webs with a width that is reduced at the curves on the outer corners of the grid mesh openings. When the duct tube is pushed onto the nuclear reactor fuel element, there is a danger that the duct tube will rotate with respect to the nuclear reactor fuel element about the longitudinal axis of the duct tube, as seen in cross section, so that the lower edge of the duct tube rests directly on an outer corner of a corner grid mesh opening of a spacer and becomes caught there. This danger arises particularly when a used duct tube, and therefore one which is somewhat twisted, for example, around its longitudinal axis, is pushed onto the nuclear reactor fuel element. No duct tubes are associated with nuclear reactor fuel elements which are intended for a pressurized water nuclear reactor, but in the reactor core of such a pressurized water nuclear reactor there are a series of similarly constructed nuclear reactor fuel elements with parallel longitudinal axes, disposed like chess board squares closely adjacent each other. Therefore, when loading or unloading a pressurized water nuclear reactor with the individual nuclear reactor fuel elements, nuclear reactor fuel elements, especially those diagonally adjacent each other in the reactor core, can still become caught at the outer corners of the corner grid mesh openings of their spacers when the spacers are constructed as in the conventional nuclear reactor fuel elements intended for boiling water nuclear reactors. This type of hooking of diagonally adjacent nuclear reactor fuel elements can lead to a destruction of the outer webs of the spacers of these nuclear reactor fuel elements, so that these nuclear reactor fuel elements cannot be re-inserted into the reactor core of the pressurized water nuclear reactor. Nuclear reactor fuel elements which have become greatly warped in the reactor core due to operational stresses have a particular tendency to become caught. It is accordingly an object of the invention to provide a nuclear reactor fuel element which overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type, to avoid using spacers when duct tubes are pushed onto nuclear reactor fuel elements and to avoid the hooking of spacers to spacers of adjacent nuclear reactor fuel elements when nuclear reactor fuel elements are inserted into reactor cores. With the foregoing and other objects in view there is provided, in accordance with the invention, a nuclear reactor fuel element for receiving mutually parallel rods especially fuel rods containing nuclear fuel, comprising a rectangular grid-shaped or latticed spacer including planar webs crossing and facing the rods at right angles defining grid mesh openings receiving the rods, the webs including two outer webs forming an outer corner of the spacer and defining a corner grid mesh opening at the outer corner, the outer corner having an outward curve being curved around a direction parallel to the longitudinal direction of the rods, the outer webs having edges at the curve transverse to the rods being drawn inward toward the rods in the corner grid mesh opening forming a bevel in longitudinal direction of the rod. The edges of the two outer webs drawn in toward the rod ensure a hooking-free sliding of both a duct tube and a spacer of an adjacent nuclear reactor fuel element in a reactor core. In accordance with another feature of the invention, the edges of the outer webs form edges of a channel on the curve. This channel can ensure coolant flow on the outside of the rod passing through the corner grid mesh opening of the spacer, which is not obstructed by the spacer. In accordance with a concomitant feature of the invention, the two outer webs together include a one-piece angular part forming the curve and a remaining part of each outer web secured to the angular part at locations spaced from the curve. Thus it is possible to avoid fastening points of the two outer webs with overlapping on the curve which encourages hooking. Other features which are considered as characteristic for the invention are set forth in the appended claims. Although the invention is illustrated and described herein as embodied in a nuclear reactor fuel element, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
047553456	claims	1. An antenna for radiating rf energy into a magnetically confined plasma within a vacuum vessel, comprising: an inductive rf energy radiating element having a length substantially shorter than a half wavelength of the rf wavelength and disposed adjacent to said plasma; first and second variable capacitors connected respectively between opposite ends of said radiating element and a common connecting point; an input coaxial feedline having an outer conductor connected to said common connecting point of said first and second capacitors and an inner conductor connected to said radiating element at a fractional distance .alpha. of the length of said radiating element from one end of said radiating element to provide a real input impedance for said antenna which is matched to the input feedline impedance for feeding power to said antenna at a selected operating frequency in a manner to form first and second resonant loops having essentially equal currents I.sub.1 and I.sub.2, respectively, which flow in the same direction through said radiating element, wherein said current I.sub.1 flows through said first capacitor and a length 1-.alpha. of said radiating element into said inner conductor of said feedline and said current I.sub.2 flows out of said inner conductor of said feedline through a length .alpha. of said radiating element and said second capacitor; a drive means coupled to said first and second capacitors for varying the capacitances thereof so that the input impedance of said antenna may be varied to match the impedance of said coaxial feedline while maintaining resonance in said first and second resonant loops; and a vacuum sealed housing means for vacuum sealed mounting of said antenna in an access port of said vacuum vessel. 2. The antenna as set forth in claim 1 wherein said inner conductor of said feedline is connected to said radiating element at a fractional distance .alpha..gtoreq.0.5 from one end of said radiating element to provide a real input impedance for said antenna which may be matched to the feedline impedance over the adjustable capacitance range of said first and second capacitors. 3. The antenna as set forth in claim 2 wherein the commonly connected electrodes of said first and second capacitors and the outer conductor of said coaxial feedline are connected to ground potential. 4. The antenna as set forth in claim 3 wherein said input coaxial feedline has a characteristic impedance of about 50 ohms said first and second capacitors are variable over a range of capacitance of from about 50 to 1000 picofarads and wherein .alpha. is selected in the range of from 0.5 to about 0.9. 5. The antenna as set forth in claim 4 wherein said selected operating frequency is in the range of from about 40 to 100 MHz at power levels greater than 2 MW. 6. The antenna as set forth in claim 5 further including means for adjustably positioning said antenna relative to said plasma. 7. The antenna as set forth in claim 6 further including an electrostatic shielding means disposed between said radiating element and said plasma to maximize magnetic field coupling of the radiated power from said radiating element into said plasma.
	abstract	This application relates to manufacturing of vacuum chambers of nuclear fusion reactors, and more particularly to a method, device and apparatus for machining grooves of poloidal segments of a vacuum chamber of a nuclear fusion reactor, and a computer-readable storage medium. The method includes: collecting three-dimensional (3D) point cloud data of surfaces of individual poloidal segments of the vacuum chamber; performing reverse model reconstruction, based on the three-dimensional point cloud data, to generate an actual 3D model to acquire a sectional view of the vacuum chamber; extracting a cross-reconstruction region between two adjacent poloidal segments; and calculating a target machining allowance of individual poloidal segments according to the cross-reconstruction region and a preset segment boundary to generate a machining strategy for the groove of individual poloidal segments.
	summary
048470376	summary	This invention relates to an apparatus for the inspection of nuclear reactor fuel rods, which are combined into fuel rod clusters in a fuel assembly, wherein fingers of a test probe which are fitted with ultrasonic test heads on several levels are insertable into spaces between the fuel rods. Such an apparatus is known from German Published, Non-Prosecuted Application 34 19 765 corresponding to U.S. Pat. No. 4,683,104. In that device, the probe can be moved parallel to the longitudinal direction of the fuel assembly to permit inspection on several levels. The vertical movement of the probe over several meters (a fuel assembly is approximately 4 meters long) requires a precise and consequently elaborate, spindle drive mechanism. For reasons of radiation protection, the fuel assembly as well as the apparatus are disposed in a water-filled pool. The vertical travel of the probe to the various test levels must therefore take place slowly. The test operation which is executed successively at the various levels, especially the required vertical movement of the probe, contributes to a considerable expenditure of time. Since the inspection of the fuel rods takes place with the reactor plant shut down, the inspection time is lost from the time that the nuclear power plant is available. It is accordingly an object of the invention to provide an apparatus for the inspection of nuclear reactor fuel rods, which overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type and which reduces the inspection effort, while nevertheless ensuring a precise positioning of the probe in the direction of the spaces to be passed through. With the foregoing and other objects in view there is provided, in accordance with the invention, an apparatus for the inspection of nuclear reactor fuel rods combined in fuel rod clusters with spaces therebetween in a fuel assembly, comprising test probes each being disposed at a respective level along the fuel assembly, fingers each being part of a respective one of the test probes, ultrasonic test heads each being disposed on a respective one of the fingers, means for inserting the test heads into the spaces between the fuel rods, and means for correcting the insertion position of each of the test probes independently of the insertion position of the others of the test probes, before insertion of the test probes. This apparatus ensures that it will be possible to cope with an inclined position of the fuel assembly or a bowing or bending of the fuel rods (a deviation from normal) without any problems, ie. without the risk of a test probe running into a fuel rod. It is only the separate positioning that allows simultaneous testing on several levels. In accordance with another feature of the invention, there is provided a rack holding the probes assigned to the levels, the inserting means moving the rack together with the probes in a given insertion direction of the probes, and a common drive moving the probes at all of the levels transverse to the given insertion direction. This simply constructed rack, which does not take up any more space than the conventional apparatus with vertically movable probes, allows the joint movement of the probe to be carried out both in the insertion direction and transversely thereto. In accordance with a further feature of the invention, the rack has a lower surface, and there is provided a support plate having brackets, at least two mutually parallel spindle nuts fixed on the lower surface of the rack, and spindles mounted in the brackets and engaging in the spindle nuts for moving the rack and the support plate. This structure provides for integration of the sequence of movement and for the support of the rack. In accordance with an added feature of the invention, the rack has bearing points at each of the levels, shafts disposed at the bearing points at each of the levels, the shafts each having a central region in the form of a spindle, probe carriers in the form of spindle nuts each being disposed on a respective one of the central regions, and pairs of bars each bordering a respective one of the central regions and being fixed relative to respective one of the shafts, the bars jutting out from the shafts in the same direction as the fingers of the probe by a distance at least equal to the diameter of a fuel rod, the bars of the pairs being spaced apart by a distance equal to the nominal width of a fuel assembly, and the shafts being displaceable relative to the bearing points. In this case, simple mechanical side successfully perform the automatic guidance of the probes in the case of fuel assemblies which deviate from normal regarding the vertical disposition thereof. In accordance with an additional feature of the invention, the rack has opposite side walls at which the bearing points are disposed, the shafts pass through the bearing points and the side walls and have free ends protruding from the side walls, and including abutments disposed on the free ends of the shafts, and compression springs each being disposed between one of the abutments and a respective one of the side walls. This is done in order to ensure that once they have assumed their position, the bars do not adjust themselves of their own accord. In accordance with yet another feature of the invention, there are provided worm wheels each being disposed on a respective one of the shafts, tongue and groove connections securing the worm wheels on the shafts, and a worm shaft extending transversely to the shafts and simultaneously engaging all of the worm wheels. Since the position of the probes disposed on the individual levels can be corrected, the uniform movement of all of the probes in their travel from one gap to the next is thus ensured. The tongue and groove connection permits axial movement of the shaft relative to the worm wheel. In accordance with yet a further feature of the invention, there are provided hubs each being disposed on the rack for limiting axial movement of a respective one of worm wheels. The lateral fixing of the worm wheel prevents the worm wheel from following the axial movement of the shaft. In accordance with yet an added feature of the invention, there is provided a base plate for holding a fuel assembly, two struts jutting out from the base plate parallel to each other and to the fuel assembly, spindle drive mechanisms each being disposed transverse to the struts at a respective one of the levels, spindle nuts each being disposed on a respective one of the spindle drive mechanisms, probe carriers each being disposed on a respective one of the spindle nuts, and drive elements each being disposed on a respective one of the probe carriers for inserting the probes into the spaces between the fuel rods. Through the use of this structure, the probes of the various levels can be positioned independently of one another and can also execute the insertion movement independently of one another. In order to effect positioning of the probes, in accordance with yet an additional feature of the invention, there is provided a strip guiding the probe fingers, and an ultrasonic transducer disposed on the strip between the probe fingers, the ultrasonic transducer emitting sound waves in a given insertion direction of the probes and receiving returning echoes providing positional determination of the probes relative to a fuel rod. In this way, the transducer which is constructed as transmitter and receiver receives a maximum echo when the center of the probe coincides with the center of the ultrasonically exposed fuel rod. The insertion movement of the respective probe can then take place immediately. In accordance with a concomitant feature of the invention, there are provided other struts offset by 90.degree. with respect to the first-mentioned struts, and other probes disposed on the other struts at levels different from the first-mentioned levels. This makes possible the simultaneous testing of a fuel assembly from two sides. Other features which are considered as characteristic for the invention are set forth in the appended claims. Although the invention is illustrated and described herein as embodied in an apparatus for the inspection of nuclear reactor fuel rods, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
	claims	1. An X-ray tube comprising:an electron beam generation unit emitting an electron beam;a limiting electrode unit limiting the electron beam emitted from the electron beam generation unit; anda target unit comprising a target material emitting an X-ray when the limited electron beam collides with the target material,wherein the limiting electrode unit comprises an electron beam limiting electrode allowing a portion of the emitted electron beam to pass therethrough and to be delivered to the target unit,wherein the portion of the emitted electron beam has a size corresponding to a size of a focal spot of the X-ray. 2. The X-ray tube of claim 1, wherein the limiting electrode unit further comprises a penetration type electron beam limiting electrode having a limiting opening having a predetermined diameter. 3. The X-ray tube of claim 2, wherein the penetration type electron beam limiting electrode delivers, to the target unit, a portion of the electron beam having passed the limiting opening among the emitted electron beams. 4. The X-ray tube of claim 2, wherein the penetration type electron beam limiting electrode is configured to have an equal electric potential as the target unit. 5. The X-ray tube of claim 1, wherein the limiting electrode unit comprises at least one slit type electron beam limiting electrode having a slit having a predetermined width. 6. The X-ray tube of claim 5, wherein the at least one slit type electron beam limiting electrode comprises:at least one spacer having a thickness corresponding to the predetermined width; anda plurality of metal electrodes spaced by the at least one spacer. 7. The X-ray tube of claim 5, wherein the at least one slit type electron beam limiting electrode is disposed such that slits are aligned with each other at a predetermined angle. 8. The X-ray tube of claim 5, wherein the slit has an incident surface into which the emitted electron beam is incident and an emitting surface through which the portion of the electron beam is delivered to the target unit, and a width of the incident surface is greater than a width of the emitting surface. 9. The X-ray tube of claim 1, wherein the electron beam limiting electrode is made of at least one of tungsten, molybdenum or gold. 10. The X-ray tube of claim 1, further comprising a filter disposed between the target unit and an object to which the X-ray is delivered, the filter being configured to remove a low energy X-ray. 11. The X-ray tube of claim 10, wherein the filter is integrally provided with the target unit. 12. The X-ray tube of claim 1, wherein the electron beam generation unit comprises a cathode emitting the electron beam, and the target unit comprises an anode. 13. The X-ray tube of claim 12, wherein the electron beam generation unit further comprises a focusing unit focusing the electron beam emitted from the cathode in a micrometer-scale.
	summary
050154346	claims	1. In a boiling water reactor having a reactor vessel, a core for containing a reaction within said reactor vessel, and a plurality of vertical in-core guide tubes extending from outside the reactor vessel into the core of said vessel at spaced apart locations, said vertical in-core guide tubes extending upwardly to the bottom of core to permit the insertion and removal of monitoring strings having local power range detectors for measuring the thermal neutron flux density interior of the core, the improvement comprising: a string having a plurality of local power range detectors, each monitor including a cathode; fissionable material on said cathode; an anode insulating material; and wiring connecting each said anode and cathode from a position on said string interior of said core to a position through said in-core guide tube exterior of said reactor vessel, each said local power range detector being placed in spaced apart relation along an end of said string whereby when said string is inserted to the end of said vertical guide tubes in said core, said local power range monitors will be in spaced vertical relation along said conduits in said core for measuring the thermal neutron flux; said string having a corresponding plurality of gamma thermometers, each said gamma thermometer provided along the length of said string at a position immediately adjacent a local power range monitor, each said gamma thermometer for monitoring the temperature of said gamma thermometers with respect to a reference to determine the gamma flux of said reactor adjacent said local power range monitor whereby during conditions of steady state power operation readings of said gamma thermometers can be used for the calibration of said local power range monitors. providing a monitoring string, said monitoring string having a plurality of local power range monitors including an anode, a cathode, fissionable material placed on said cathode and mineral insulated connecting each said anode and cathode in parallel to remote leads for connection to monitoring current reading instrumentation, each said local power range monitor being spaced in spaced apart relation along said string; providing further in said string, gamma thermometers, each gamma thermometer including a mass for absorbing gamma rays and varying in temperature with respect to the flux of said absorbed gamma rays, said gamma thermometer including a reading thermocouple and a reference thermocouple; each said gamma thermometer placed immediately adjacent a local power range monitors; providing connection means for each said gamma thermometer to conventional paired leads for reading said thermocouples to determine gamma flux interior of said reactor; operating said reactor at a steady power state; taking an energy balance of said reactor to determine the reactor power output; relating the power output at any portion of said reactor to a gamma thermometer reading; taking the reading of a corresponding and immediately adjacent local power range monitor; and calibrating the determined neutron flux from the reading of said local power range monitor to the reading of said gamma thermometer for the overall calibration of said local power range monitor. 2. The invention of claim 1 and including four local power range monitors and four or eight gamma thermometers on said string. 3. A process of calibrating local power range monitors in a boiling water reactor by a calibration detector inserted into a vertical in-core guide tube exterior of said vessel, said vertical in-core guide tube passing upward into the interior of said vessel core, said calibration process comprising the steps of;
051494922	summary	BACKGROUND OF THE INVENTION The present invention relates to a reactor containment vessel of a nuclear power plant and more particularly to improvements relating to a cooling system of the nuclear power plant to remove decay heat in the case of breaking of tubes or the like on an accident. If an accident happens in a reactor by any possibility, it is necessrary to remove decay heat by means of cooling a reactor. In reactor containment vessels there have been proposed various kinds of cooling systems for removing the decay heat. For example, it is known that a suppression chamber and isolation condenser (emergency condenser) are respectively provided as a cooling system without using dynamic device like a pump. The reactor containment vessel is generally composed of a drywell and a wetwell, and the suppression chamber is provided in the wetwell to communicate with a drywell through a suppression vent pipe wherein pool water is charged. The isolation condenser is connected to a main steam line extending from the reactor pressure vessel to remove decay heat from steam introduced therein. The provision of such a system makes cooling operation of the nuclear power plant reliable. If an accident happens in the reactor, for example, in the case of the loss of coolant accident (LOCA), the decay heat produces steam in the reactor pressure vessel. The steam is introduced into the isolation condenser through the main steam line. The introduced steam is condensed in the isolation condenser and returned to the reactor pressure vessel as condensate by gravity. When the main steam line is broken in the drywell, the steam produced by the decay heat is released into the drywell from the reactor pressure vessel through the broken main steam line. Then non-condensable gas charged in the drywell is mixed with the steam and introduced into heat exchanger tubes of the isolation condenser. Such an invasion of non-condensable gas causes the heat-exchanging performance of the heat exchanger tubes to deteriorate. To cope with these problems, in the above-mentioned conventional structure, the isolation condenser is provided with a non-condensable gas vent pipe which vents the non-condensable gas in the heat exchanger tubes to the suppression chamber. However, if the pressure in the drywell becomes almost equal to that in the suppression chamber, the end of the non-condensable gas vent pipe is sealed by the suppression pool water and the non-condensable gas vent pipe stops venting the non-condensable gas to the suppression chamber. However, if residual non-condensable gas exists even a little in the heat exchanger tubes, the existance of such non-condensable gas causes condensation heat transfer to deterioate. It is known by experiment that when the non-condensable gas is 10% at mass rate to the steam, the condensation heat transfer degrades at about 20% as compared with the case without non-condensable gas. Accordingly, to prevent the degradation of heat transfer characteristics in the isolation condenser, it is desirable that non-condensable gas should be excluded from the heat exchanger tubes as much as possible. SUMMARY OF THE INVENTION An object of the present invention is to substantially eliminate defects or drawbacks encountered in the prior art and to provide an improved reactor containment vessel for preventing non-condensable gas from invading into an isolation condenser and an improved isolation condenser for promoting the non-condensable gas to be vented from the isolation condenser heat exchanger so as to remove decay heat efficiently when a main steam line is broken. This object can be achieved according to the present invention, by providing one opening of a suppression vent pipe at a substantially corresponding level to a main steam line with providing of a communication pipe for introducing non-condensable gas toward a lower area of a drywell and providing a non-condesable gas vent pipe of an isolation condenser toward the lower area of the drywell, which branches from a non-condensable gas vent pipe of the isolation condenser toward a suppression chamber. According to the reactor containment vessel of the structure or character described above, in the case of breaking of the main steam line, non-condensable gas in the vicinity of the main steam line in the drywell is introduced with steam into a suppression chamber of a wetwell through the suppression vent pipe, thus reducing a quantity of non-condensable gas to flow into the isolation condenser through the main steam line. Further, when the drywell is succesively cooled by the isolation condenser, the pressure in the drywell is equal to or lower than that in the suppression chamber. When the pressure in the dry well becomes almost equal to that in the suppression chamber, the non-condensable gas vent pipe of the isolation condenser toward the suppression chamber is plugged by the suppression pool water and stops venting the non-condensable gas. Even in this case, the gas vent pipe toward the lower area of the drywell continues venting the non-condensable gas to the drywell. When the pressure in the drywell decreases lower than that in the suppression chamber, the vacuum breaker opens and the non-condensable gas flows back to the drywell from the suppression chamber. Even in this case, the vent pipe of the vacuum breaker connects to the lower area of the drywell, the non-condensable gas is introduced to the lower area of the drywell from the suppression chamber, thus preventing an invasion of the introduced non-condensable gas into the isolation condenser.
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	description	This application claims the benefit of U.S. Provisional Application No. 60/489,047, filed Jul. 22, 2003. This Provisional Application is hereby incorporated herein by reference in its entirety. The present invention relates to x-ray analysis of materials. In particular, the present invention relates to x-ray diffraction techniques for analysis of sample surfaces, especially for in-situ measurement of samples during fabrication thereof. X-ray analysis techniques have been some of the most significant developments in twentieth-century science and technology. The use of x-ray diffraction, spectroscopy, imaging, and other x-ray analysis techniques has led to a profound increase in knowledge in virtually all scientific fields. One existing class of surface analysis is based on diffraction of x-rays directed toward a sample. The diffracted radiation can be measured and various physical properties, including crystalline structure and phase, and surface texture, can be algorithmically determined. These measurements can be used for process monitoring in a wide variety of applications, including the manufacture of semiconductors, pharmaceuticals, specialty metals and coatings, building materials, and other crystalline structures. This measurement and analysis process requires the detection of diffracted x-ray information at multiple locations in reference to the sample. Conventional diffraction systems are large, expensive and prone to reliability problems. Their size, cost, and performance limit their use to off-line “laboratory” settings. There is a strong drive in the market for applying this technology to in-line process monitoring—allowing real-time process control. This type of in-line or “in-situ” measurement leads to certain practical concerns—such as the need for smaller instruments, and for sample handling and excitation/detection techniques compatible with the surrounding production environment. For example, the sample may be continuously moving past the instrument on a movement path. The technique must be compatible with both the sample movement and the movement path. These capabilities are provided by the present invention, which in one aspect is an x-ray diffraction measurement apparatus for measuring a sample, having an x-ray source and detector coupled together in a combination for coordinated rotation around the sample, such that x-ray diffraction data can be taken at multiple phi angles. The apparatus may provide a pole figure representation of crystal orientation of the sample, wherein the pole figure represents the crystal alignment, and a full width half maximum value is calculated from the pole figure for crystal alignment quantification. Data may be taken at discrete positions along a length of the sample, and the sample is in a fixed position during measuring; or data may be taken continuously along a length of the article, as the sample continuously moves along its length in a movement path between the source and detector. The sample may be in the form of a tape or sheet, linearly passing through a measurement zone between the source and detector. The apparatus may include a polycapillary x-ray optic for directing a parallel x-ray beam toward the sample from the source. The apparatus may include a substantially u-shaped plate affixed to the source at one arm and the detector at the other arm; a vertical post supporting the sample; and a base plate under the sample and rotatable around the post. The u-shaped plate may be affixed to the base plate such that it rotatably suspends the source and detector about the sample area. The present invention also extends to the methods of rotatably mounting a source/detector combination about a sample, to provide an in-situ, process-compatible diffraction measurement technique. FIG. 1 shows an XRD system 100 for determining the crystallographic texture of a reel-to-reel spool-fed continuous sample 110. In this example, the sample is a tape-like configuration, having a high aspect ratio over the sample area. For example, in a superconducting tape embodiment of the present invention as disclosed in copending Application entitled “METHODS FOR FORMING SUPERCONDUCTOR ARTICLES AND XRD METHODS FOR CHARACTERIZING SAME” filed o/a 16 Jul. 2003 in the name of Jodi Reeves as Docket# 1014-SP231, Ser. No. 60/487,739, the entirety of which is hereby incorporated herein by reference, the width of the tape is generally on the order of about 0.4-10 cm, and the length of the tape is typically at least about 100 m, most typically greater than about 500 m. Indeed, embodiments of the present invention provide for superconducting tapes that include a substrate having a length on the order of 1 km or above. Accordingly, the substrate may have an aspect ratio that is fairly high, on the order of not less than 103, or even not less than 104. Certain embodiments are longer, having an aspect ratio of 105 and higher. As used herein, the term ‘aspect ratio’ is used to denote the ratio of the length of the substrate or tape to the next longest dimension, the width of the substrate or tape. Turning back to FIG. 1, the tape 110 unwinds from a payout spool 112 and winds onto a take-up spool 122 in reel-to-reel fashion, threading through a sample holder 136 and making physical contact with an encoder 132 or a tape location reader. The encoder 132 provides position tracking and also provides a way to monitor the translation rate of the tape 110 as it translates through the XRD system 100. An alternate way to provide position tracking is to use a tape location reader that utilizes a bar code or dot matrix read head to measure and communicate the exact distance along the length of the tape 110 at which measurements are being performed. The tape location reader may additionally provide information identifying the sample. A motor 114 such as a stepper motor drives the rotation of the payout spool 112 and advances the tape 110 through the XRD system 100 a desirable increment while a motor 124 such as a torque motor drives the rotation of the take-up spool 122 and provides a desirable amount of tension in the tape 110. Further included in the sample holder 136 is a vacuum port with holes machined through the body of the sample holder 136, that are connected to a pump 138, all to optionally hold the sample against the sample holder. Controller 144 provides a control function, as discussed in greater detail below. In accordance with the present invention, a source 140 and detector 142 are in fixed relation to each other, and rotatably mounted around the sample holder on a fixture (not shown—discussed further below) to cover all necessary analysis (phi) angles of interest on a portion of the tape, while not interfering with the tape's movement path. In this example, the source and detector pair are aligned along axis “A” such that the source 140 that provides a parallel incident beam of x-ray radiation, such as copper Kα radiation, onto the tape 110, and detector 142 detects the diffracted x-rays along the same axis. For characterization of biaxially textured thin layers or films according to embodiments of the present invention, use of an x-ray source/optic combination that generates parallel x-ray incident beams is desirable. In this regard, use of an x-ray source generating a parallel x-ray incident beam advantageously improves the integrity of the data measured through characterization, as compared to techniques which utilize divergent beams for characterization. More specifically, the precise position of the tape as it translates through the characterization zone, most notably, in the z-direction, affects the precision of the x-ray measurement when relying on systems incorporating divergent beams. In contrast, use of a parallel beam minimizes the affect a variance in the actual z-direction location of the tape undergoing characterization. Such parallel beam transmission can be produced by a polycapillary collimating optic/source combinations such as those disclosed in X-Ray Optical Systems, Inc. U.S. Pat. Nos. 5,192,869; 5,175,755; 5,497,008; 5,745,547; 5,570,408; and 5,604,353; U.S. Provisional Applications Ser. Nos. 60/398,968 (filed Jul. 26, 2002 and perfected as PCT Application PCT/US02/38803) and 60/398,965 (filed Jul. 26, 2002 and perfected as PCT Application PCT/US02/38493)—all of which are incorporated by reference herein in their entirety. The x-ray source 140 and the detector 142 are oriented within the XRD system 100 such that the incident beam impinges upon the tape 110 at a given angle from the surface of the tape and produces a diffracted beam, also at a given angle to the surface of the tape 110. In the case of YSZ (yttria-stabilized zirconia), that angle is typically about 15° (see FIG. 3). Of course, for different materials, the incident and diffracted beam angles may be at different angles, as the particular physical angles are generally material dependent. The XRD system 100 can be used for a variety of sampling materials by setting the incident angle and the detector angle differently. A goniometer (not shown) may be functionally connected to the sample holder 136 and enables movement of the sample holder 136 through a plurality of motions and angles, including rotation through a range of φ-angles in conjunction with the positioning of the payout spool 112 and the take-up spool 122, respectively. Optionally, the system may include a laser-positioning functionality for sample height calibration. A controller 144 is in communication with the motors; the encoder 132; the pump 138; the x-ray source 140; and the detector 142. The controller 144 mathematically interprets the diffraction patterns created at the detector 142, yielding quantitative information about the texture of the layer of tape 110 subjected to characterization, which may include the substrate itself in the case of a textured substrate. The graphs produced by the controller 144 are coordinated with sample-identifying information as communicated to the controller 144 by the encoder 132. The final output of the controller 144 is in-plane texture (not just intensity) as a function of position along the tape 110, as is described in reference to FIG. 6 and FIG. 7, discussed in more detail below. The controller 144 may be embodied as a system personal computer (PC), data acquisition software, control software such as LabView, and a set of interfacing components. In operation, the tape 110 is subjected to characterization at XRD system 100 to undergo texture analysis, and most typically, in-plane texture analysis. While the precise form of the embodiment shown in FIG. 1 is readily adaptable for characterization ex-situ, it may be used in-situ as well, discussed in more detail with other embodiments herein. Further operational details are as follows: The tape 110 is manually threaded from the payout spool 112 through guides on the sample holder 136 and onto the take-up spool 122. The encoder 132 may physically contact the tape 110. The controller 144 next advances the tape 110 through the XRD system 100 by driving the motor 114 and the motor 124, which drive the rotation of the payout spool 112 and the take-up spool 122, respectively. The encoder 132 measures the distance translated by the tape 110 and at a predetermined increment, e.g., every 10 centimeters, as programmed within the controller 144, the controller 144 halts the translation of the tape 110 through the XRD system 100 by disengaging the motors 114 and 124. The controller 144 engages the pump 138, creating a vacuum through the vacuum ports that adheres the tape 110 flatly within the sample holder 136 and maintains the tape 110 at a fixed vertical height. The controller 144 begins the texture analysis by communicating to the x-ray source 140 to emit the incident beam 120, which impinges upon the tape 110 at an appropriate angle, e.g., 15° for YSZ or 16.4° for a YBCO (YBa2Cu3O7−x), and produces the diffracted beam, which is collected at the detector 142 and creates a diffraction pattern that is communicated back to the controller 144. Data is collected by the detector 142 for a time interval of, for example, 10 seconds, after which time the controller 144 communicates to the x-ray source 140 to discontinue generation of the incident beam. The controller 144 then may engage another motor (not shown) controlling the rotation of the source and detector motor 118 through an appropriate φ-angle, e.g., 5°. The controller 144 then communicates to the x-ray source 140 to emit the incident beam, and data is again collected at the detector 142 and communicated to the controller 144 for a similar time interval. The process continues until data has been collected at various phi angles through a range of phi angles. Typically, data is taken at multiple phi angles, usually at least 3, more typically at least 4, and generally within a range of about +/−5 to +/−25 degrees, more typically about +/−8 to +/−15 degrees. In one embodiment, a range of φ-angles, e.g., at increments of 5° from −25° to 25°. Even greater phi angle ranges can be obtained, without interfering with the tape's movement path, in an in-situ embodiment. The motor 114 and the motor 124 are reengaged by the controller 144 and advance the tape 110 another increment, e.g., 10 cm, through the XRD system 100 and the measurement process is repeated, such that data collected by the controller 144 can be plotted as a function of position along the tape 110. The encoder 132 communicates to the controller 144 position information for the tape 110 that gets paired with the gathered x-ray texture data. Alternatively, the measurements can all be accomplished while the tape is moving, and at multiple phi angles. The present invention can be used in connection in any application in which diffraction-type measurements are made on a sample surface. One exemplary application is that of high temperature superconductors as discussed herein. FIG. 2 shows a top view of an HTS processing apparatus employing the principles disclosed above, notably an XRD system 1000 for determining the crystallographic texture of a reel-to-reel spool-fed continuous tape. XRD assembly 1000 may also be moveably mounted to a track 932 such that the XRD assembly 1000 itself may translate horizontally through certain in-situ processing sites using its own motor. As shown in detail in FIGS. 2 and 3, the XRD assembly 1000 includes a low-power source 1110 that emits x-ray radiation, which is collimated by an optic 1112 that produces a parallel incident beam 1120 of high intensity, in a similar manner as described above in connection with FIG. 1. The incident beam 1120 interacts with the thin film overlying the tape 110 at an incident angle, which, in the case of YSZ is typically about 15°, to generate a diffracted beam 1122 that is collected at a low-power, high-resolution detector 1116 (e.g., energy sensitive). The source 1110 and the detector 1116 are low power to minimize cooling requirements. The XRD assembly 1000 is vacuum compatible, and thus the source 1110, the optic 1112, and the detector 1116 incorporate the appropriate shielding to prevent contamination and deposited species build-up. The source 1110 may be functionally attached to a track 1114 and the detector 1116 may be functionally attached to a track 1118 such that the motion of the source 1110 and the detector 1116 are coupled together for coupled rotation in φ-space. Coupling may be carried out through physical deployment on a single base that rotates along the tracks 1114 and 1118 (or see the embodiment of FIGS. 4 and 5 for a pivoting embodiment of such coupling), or through synchronized coupling electronically. In this regard, the source and detector need not necessarily rotate at the same rate, provided that they are both properly positioned for the targeted phi angle measurement. In-plane texture of the layer under examination is analyzed via the XRD assembly 1000 as the tape 110 translates through its processing environment, such that the source 1110, the optic 1112, and the detector 1116 are oriented with respect to the tape 110 to perform x-ray diffraction analysis. The optic 1112 collimates x-ray radiation emitted by the source 1110 and produces the parallel incident beam 1120, in contrast to some systems that rely on divergent beams for characterization. As discussed above, the parallel x-ray beam is particularly beneficial for use in systems that have the capability of continuous movement of the tape. In such systems, the parallel beam provides improved process control, as z-axis position of the tape (generally vertical direction) can be difficult to precisely control during continuous movement. The incident beam 1120 interacts with the thin film deposited atop the tape 110 to produce the diffracted beam 1122, which is collected at the detector 1116 and creates a diffraction pattern that is communicated back to the controller. Data is collected by the detector 1116 for a time interval of, for example, 0.1 to about 20 seconds (typically 0.1 to about 10 seconds, more typically 1 to about 5 seconds), after which time the controller communicates to the source 1110 to discontinue generation of the incident beam 1120. A coupled rotation through a predetermined φ-angle next occurs between the source 1110 and the detector 1116 along the tracks 1114 and 1118, respectively. The source 1110 then emits x-ray radiation that is collected as the diffracted beam 1122 at the detector 1116 for a similar time interval, after which time the source 1110 e.g., discontinues emission of x-ray radiation and a coupled rotation through another predetermined φ-angle occurs between the source 1110 and the detector 1116 along the tracks 1114 and 1118, respectively. The process continues for a range of phi angles. For example, x-ray diffraction measurements may be performed by the XRD assembly 1000 at phi (φ)=0°, φ=−10°, and φ=+10°, although a range of φ-motion is enabled by the assembly between −25° and 25°. At the conclusion of data gathering through the range of φ-angles at a particular, the entire assembly itself can be moved to a different part of the process along track 932 if needed. Parameters that may be controlled include tape translation rate (speed), temperature, pressure, gas flow, gas species flow, composition, and combinations thereof. It is noted that while in the foregoing embodiment, the XRD system typically gathers diffraction data through an area of the tape, as a function of translation rate and sampling duration, the tape could be stopped and discrete points on the tape measured. However, continuous data sampling along an area of the tape during continuous movement may be desirable for processing. While the foregoing embodiments generally rely on a single source/detector pair for measuring diffraction data at multiple phi angles, the multiple phi angle data can be gathered through alternative structures. For example, multiple detectors, multiple sources, or a combination of multiple sources and detectors can be utilized. In the case of multiple detectors and sources, they may be disposed as shown by the dotted lines in connection with XRD assembly 1000. Alternatively, a single source may be used, to emulate multiple sources. In this case, the source can have incident beams routed to specific phi angles through use of appropriate optics, thereby forming multiple source points from a single source. However the particularities of the source/detector system are embodied, according to one embodiment, it is generally desirable that the system have the capability of multiple phi angle measurement, which enables calculation of pole figures and derivation of FWHM values for superior characterization of the HTS tape under fabrication or under inspection. FIG. 4 is a top, isometric view of another XRD assembly 2000 in accordance with the present invention; and FIG. 5 shows a side, isometric view of this XRD assembly. In this embodiment, the source 2110/optic 2112 assembly is known as a low-power X-Beam® source as disclosed in the above-identified X-Ray Optical Systems, Inc. US provisional and PCT patent applications. The source 2110 is rigidly mounted to a rigid support structure, e.g., an approximately U-shaped plate 2120 which traverses around and under the sample holder 2136 (forming the tape 110's movement path). Here, the sample holder is fixedly mounted to a stationary post 2140. The detector 2116 is also rigidly mounted to the other end of plate 2120. In one embodiment, the detector is a semiconductor, energy-sensitive detector with a detector area of about 25 mm2. Plate 2120 can be fixedly attached to a horizontal, rotating plate 2130 with brackets 2150 such that the source/detector combination can rotate around the sample 110, through the requisite phi angles, but without interfering with the tape's linear movement path in and out of the measurement area. The sample may move continuously through the measurement zone using the actuator principles discussed above, or can be fixed during measurement. Notably in this example, plate 2120 is approximately U-shaped, and fixedly suspends the source/detector combination over the sample 110, and is tilted (somewhat wrapped) around the post 2140 to provide a coordinated, symmetric beam movement through the requisite phi angles. Tilting can also be used to achieve the requisite chi (tilt) angle of about 55 degrees in one embodiment. This movement can be accomplished manually, or using a controllable motor 2170. The entire assembly can be supported by a base structure 2160. While the source and detector are shown directly opposed on axis “A” (FIG. 1), they only need to be in some fixed relationship during rotation, not necessarily opposing. Other improvements to the assembly of FIGS. 4 and 5 are possible. For example, plate 2120 could be hingedly attached to the underlying plate 2130 to provide an additional degree of angular (chi angle) adjustment (either manually or by controllable motor); and the source and/or detector could also be mounted with some adjustment. However, during measurement, these adjustments generally stop, except for the rotational movement of the source/detector combination through the phi angles. In addition, the entire apparatus could be arranged over a sheet-like material, and provide the same angular rotatability over the area under measurement. A separate material with differing diffraction characteristics (e.g., silicon wafer slice) could be added to the upper surface of the sample holder (and underneath the sample itself) to suppress background diffraction of other portions of the sample holder. This is especially useful for smaller samples for which the parallel beam may overlap the sample's edges. Interpretation of Results: The final output of the controller is in-plane texture as a function of position along the tape 110, as is described below in reference to FIG. 6 and FIG. 7. FIG. 6 shows a plurality of diffraction patterns 1300 that are generated due to the constructive interference in the diffracted beam that occurs when the Bragg equation is satisfied in conjunction with the regularly repeating crystalline structure of the grains within the thin film atop the tape 110. The Bragg equation relates the angles at which X-rays are scattered by planes with an interplanar spacing (d) and states:nλ=2d sin θ where n is an integer, λ is the wavelength of incident radiation (constant), d is the interplanar spacing, and θ is the incident angle of the x-ray beam. In satisfying the Bragg equation, diffraction occurs at a specific θ-angle for each unique set of planes within a particular grain. In the case of YSZ, a diffraction signal recorded at 2θ=32.8° corresponds to diffraction from the (111) plane and a diffraction signal recorded 2θ=34.9° corresponds to the (201) plane of YSZ. Of course, such 2θ angles are material specific. With respect to a YBCO superconductor layer a diffraction signal recorded at 2θ=32.8° corresponds to diffraction from the (103) plane and a diffraction signal recorded 2θ=38.5° corresponds to the (005) plane. Information about the orientation of the individual grains that comprise the layer under study is contained in the diffraction patterns 1300. Each diffraction pattern corresponds to a different φ-angle, and three φ-angles and their corresponding diffraction patterns 1300 are shown in FIG. 6 for illustrative purposes. In practice, it is likely that a diffraction pattern is recorded for each 5° increment between φ=−25° and φ=25°. As a sidenote, when planes are being described, (001) is used to describe one plane and {001} is used to describe a family of planes. When diffraction directions are being described, [001] denotes a direction and <001> denotes a family of directions. For an XRD system, it is the planes that are doing the diffracting; however, the data in the diffraction pattern is usually described in terms of diffracting directions. Each constructive interference spot, called a diffraction peak, occurs at a specific location on a specific circle (of varying phi angles) of constant 2θ-angle, where different diffracting planes will produce diffraction peaks at different 2θangles. In the ideal case, in which all grains are perfectly aligned with respect to one another, the diffraction peaks appear as dots. In the worst case, in which all the grains are randomly oriented with respect to one another, the diffraction peaks appear as solid rings that occur along the curves of constant 2θ-angle. In the typical case, in which there is a substantial degree of in-plane grain misalignment within the thin film, diffraction peaks appear as elongated spots. In the particular case of YSZ, since the grains of the thin film are grown such that the c axis of their unit cells are approximately parallel to each other, the grains are well aligned in the [001] direction and the diffraction peaks appear as dots along the 2θ-angle=35° curve, which corresponds to diffraction by the {001}planes. The diffraction peaks along the 2θ-angle=35° curve remain undiminished in intensity as the tape 110 is rotated through the range of φ-angles away from φ=0° because the c axis of the unit cells does not change relative to the incident beam 210. Further, since there is some degree of in-plane grain misalignment along the [110]direction, the diffraction peaks that occur on the 2θ-angle=30° curve, which corresponds to the {111 } planes, appear as elongated spots, and diminish in intensity as the tape 110 is rotated through the range of φ-angles away from φ=0°, because the greatest number of grains is aligned along the [110] direction and fewer and fewer grains occur aligned at greater phi angles, as is illustrated in the three diffraction patterns 1300 corresponding to φ=10°, φ=0°, and φ=−10°. While the (110) plane is the plane of interest to quantify the range of in-plane misalignment that occurs between grains, due to the fact that the [110] direction lies within the plane of the tape 110 and lies parallel to the tape length direction, it is generally difficult to directly obtain diffraction data from the (110) plane. Instead, the {111} set of planes is studied and information, which includes a component that relates information about the {110} set of planes, is extracted. The change in intensity as the tape 110 is rotated in φ is plotted in FIG. 7, which illustrates a section of a two-dimensional pole figure 1400 that is analyzed to determine the degree of in-plane grain alignment within the thin film atop the tape 110. From the Gaussian that characterizes the pole figure 1400, the full-width at half-max (FWHM) is calculated by the controller. A large FWHM, and hence a broad peak in the pole figure 1400, implies that there is a large range of misorientation in grain alignment along the [110] direction, whereas a small FWHM, and hence a narrow peak in the pole figure 1400, implies a high degree of grain alignment along the [110] direction. According to embodiments of the present invention demonstrating grain alignment, typically, the FWHM spread is less than about 30°, most typically not greater than about 20°. Particular embodiments had a FWHM spread of not greater than about 15°, or even 10°. In the particular case of YSZ, a spread of 15° in the in-plane texture in the YSZ layer ensures that a spread of less than 10° exists in the in-plane texture in the subsequent epitaxially grown YBCO layer, thus enabling desirable a Jc performance, such as on the order of one million amperes/cm2 in the finished HTS tape. It is noted that while the foregoing focuses on characterization of a buffer layer formed at one stage of fabrication of an HTS tape, characterization may be carried out on other layers as well, such as on a textured substrate (as in the case of a RABiT substrate), and most notably, on the superconductor (HTS) layer itself. According to embodiments of the present invention, at least one of the substrate, the buffer layer (more specifically at least one buffer film of the buffer layer), and the superconducting layer has a FWHM not greater than about 25°, preferably not greater than 20°, and more preferably not greater than about 15°, or even about 10°. In this regard, assurance of low FWHM values for the substrate and/or the buffer layer are primarily important of assurance of a low FWHM for the superconductor layer, and the actual crystallographic structure and attendant FWHM for the superconductor layer are of particular significance. This technique (and its close relatives) may involve irradiating a sample area with any type of high energy radiation, such as x-rays, gamma rays, neutrons or particle beams and observing the resulting diffraction emitted by the sample area. Moreover, these techniques, while optimized in a diffraction measurement, are extendable to any measurement technique (e.g., fluorescence) using the above types of directed radiation. While superconductor tapes have formed the sample in this application, the principles are extendable to any type of sample media requiring analysis, especially elongated media moving through an in-situ measurement zone. As noted above, the embodiment disclosed is readily adapted for ex-situ use, it may be incorporated in-situ as well. Likewise, while the embodiment illustrated is particularly adapted for in-situ use (such as in a processing chamber, including IBAD processing chambers and HTS deposition chambers), it may be embodied to be an ex-situ system, such as a tabletop system. Moreover, in certain industries, the locale of such analyzers may be referred to as “in-line” where the system analyzes substantially all of the material passing through, or “at-line” where samples are readily available from the production line to insert into the analyzer. The disclosed system is readily adaptable for either of these environments. Although preferred embodiments have been depicted and described in detail herein, it will be apparent to those skilled in the relevant art that various modifications, additions, substitutions and the like can be made without departing from the spirit of the invention and these are therefore considered to be within the scope of the invention as defined in the following claims.
	description	Reference should now be made to the drawings, in which the same reference numerals are used throughout the different drawings to designate the same or similar components. As shown in FIG. 1, the instrumented capsule 1 according to a preferred embodiment of the present invention comprises a capsule main body 10 that is installed in an irradiation hole 103 of the research reactor pool 100. The instrumented capsule 1 also has a rigid protection tube 60, a flexible guide tube 70 and a junction box 80, which guide and connect a vacuum control pipe and several control wires extending from the interior of the main body 10 to a capsule control system 90 installed outside the reactor pool 100. In a detailed description of the instrumented capsule 1 of the present invention, the main body 10 of the instrumented capsule comprises a shell 11 that defines the appearance of the main body 10 as shown in FIG. 2. Housed in the shell 11 are heat media 13 used for transmitting heat from heaters to specimens. The heat media 13 collaterally hold the specimens 2 of target materials at the center and peripheral areas thereof. A plurality of insulators 23 are interposed between adjacent heat media 13 and positioned above and under the upper and lower reflectors 19, respectively. The Thermocouples 25 are set in each of the heat media 13, and are used for sensing the temperature of the specimens 2. A dosimeter 29 is installed in each of the heat media 13 so as to measure the quantity of neutron radiation. The capsule main body 10 is loaded into the irradiation hole 103 of the research reactor. The shell 11 of the main body 10 is a hollow cylindrical body, and the heat media 13 are sequentially set into the shell 11 along an axial direction of the shell 11. The specimens 2, made of a variety of target materials and having various shapes, are longitudinally set into the heat media 13, so the specimens 2 create a multi-staged specimen arrangement. The specimens 2 are fabricated in the form of rods with the same length and circular or rectangular cross-sections, and are installed in the shell 11 while being axially set at the center and peripheral areas of the heat media 13. The number of the heat media 13 may be changed in accordance with test purposes and test environments. The heat media 13 collaterally act as specimen holders, and each have a plurality of specimen seating holes at the center and peripheral areas thereof as shown in FIG. 5b. The specimen seating holes of the heat media 13 have circular or rectangular cross-sections, and receive the specimens 2 therein. The circumferential surfaces of the heat media 13 come into close contact with the inner surface of the shell 11, and two adjacent media 13 are connected to each other by a plurality of connecting pins 15. The thermocouples 25 are set into the circumferential portion of each heat medium 13 so as to detect the temperatures of the specimens 2 in the heat medium 13. The dosimeter 29 is installed in each heat medium 13 so as to measure the total neutron fluence. A coiled heater 27 is installed around the circumferential surface of each heat medium 13 so as to generate heat. The heat from the heaters 27 is transferred to the specimens 2 through the heat media 13, thus heating the specimens 13 to the target temperature. As shown in FIGS. 4a and 4b, each of the heaters 27 is a sheath-heater, and is wrapped along a spiral groove 28 formed around the circumferential surface of an associated heat medium 13. An upper reflector 19 is installed on the upper end of the uppermost heat medium 13, and a lower reflector 19 is installed under the lower end of the lowermost heat medium 13. The two reflectors 19 prevent upward and downward heat transfer from the uppermost and lowermost heaters 27 in axial directions of the shell 11. In order to fabricate each of the two reflectors 19, a plurality of circular discs 18 are layered and fastened together into a single body by using a fastening pin 20. The reflectors 19 thus have a multi-layered structure as shown in FIG. 6a. In an effort to minimize axial heat transfer between adjacent heat media 13 having specimens 2, an insulator 23 is interposed between the adjacent heat media 13 as shown in FIGS. 7a and 7b. In such a case, the insulators 23 are each fabricated in the form of a circular disc having the same diameter of the heat media 13, and are locked to adjacent media 13 by the connecting pins 15. A lower end plug 31 is mounted to the open lower end of the shell 11, while an upper end plug 33 is mounted to the open upper end of the shell 11. The upper and lower end plugs 33 and 31 thus seal the upper and lower ends of the shell 11. An upper guide spring unit 53 is fitted over the upper end of the shell 11, and comes into elastic and frictional contact with the inner surface of the irradiation hole 103 when the capsule main body 10 is installed in the irradiation hole 103. The upper guide spring unit 53 vertically places the shell 11 of the main body 10 at the center of the vertical irradiation hole 103. As shown in FIG. 12, the upper spring unit 53 has upper and lower fixing rings 52, at which the spring unit 53 is fitted over the shell 11. A plurality of wire springs 51 are connected between the upper and lower fixing rings 52 at regular positions, and are bent outward at their middle portions to project outward in radial directions. The wire springs 51 are thus brought, at their bent portions, into elastic and frictional contact with the inner surface of the irradiation hole 103 when the main body 10 is loaded in the irradiation hole 103. In the preferred embodiment of FIG. 12, the upper guide spring unit 53 has six wire springs 51 such that the capsule equipped with the spring unit 53 are loaded in an irradiation hole having a hexagonal cross-section. Of course, the number of the wire springs 51 may be changed in accordance with the cross-section of the irradiation hole in which the capsule main body 10 is installed. A specimen compressing spring 43 is installed under the upper end plug 33, and compresses the specimens 2. In order to seat the specimen compressing spring 43, a spring seat 45 is installed in the shell 11 at a position above the uppermost insulator 23. Two spacers 47 and 49 are sequentially set in the shell 11 at a position between the spring seat 45 and the uppermost insulator 23, thus spacing the spring seat 45 from the uppermost insulator 23 at a desired interval. As shown in FIG. 8, the upper end plug 33 has a central pipe hole 34 and six peripheral pipe holes 34. A vacuum control pipe 55, used for controlling the pressure of helium gas in the capsule main body 10 to control the degree of vacuum in said main body 10, passes through the central pipe hole 34 of the upper end plug 33, while six wiring pipes 57, which house the control wires extending from the thermocouples 25 and the heaters 27, pass through the six peripheral pipe holes 34. In such a case, the vacuum control pipe 55 and the six wiring pipes 57 are firmly held in the pipe holes 34 of the upper end plug 33 while accomplishing a sealing effect at the junctions of the pipes 55 and 57 and the pipe holes 34, and are guided to the junction box 80 by the protection tube 60 and the guide tube 70 while being protected by said tubes 60 and 70. The junction box 80 is installed outside the reactor pool 100, and connects the pipes 55 and 57 to the capsule control system 90. As described above, the vacuum control pipe 55 and the wiring pipes 57 extending from the capsule main body 10 are guided to the junction box 80 via the protection tube 60 and the guide tube 70. Both the protection tube 60 and the guide tube 70 shield the vacuum control pipe 55 and the wiring pipes 57 from coolant in the reactor pool 100, and accomplish the air-tightness of the pipes 55 and 57. The junction box 80 is installed outside the reactor pool 100, and connects the pipes 55 and 57 to the capsule control system 90. As shown in FIG. 13a, the junction box 80 has a guide tube connector 92 on its front surface, and the connector 92 connects the guide tube 70 to the junction box 80. In the junction box 80, the vacuum control pipe 55 and the control wires, such as wires extending from the heaters 25 and the thermocouples 27, are separated from each other. In order to separately connect the vacuum control pipe 55 and the control wires to the associated parts of the capsule control system 90, the rear surface of the junction box 80 is provided with several connectors, that is, a thermocouple control wire connector 93, a heater control wire connector 94, a vacuum control pipe connector 95, and a pressurizing tube connector 96. A grab hook 83 and a grapple head 84 are provided at the uppermost end of the protection tube 60 connected to the upper end of the capsule main body 10 as shown in FIG. 3. The grab hook 83 and the grapple head 84 are used in the process of moving, loading or unloading the capsule main body 10. In a detailed description, the capsule main body 10 is movable in the research reactor, with the grab hook 83 caught by an overhead crane (not shown) positioned above the reactor pool 100. The grapple head 84 is used for rotating the capsule main body 10 so as to fix or remove the main body 10 to or from a receptacle 105 provided at the bottom of the irradiation hole 103. That is, the capsule main body 10 is loaded or unloaded in or from the irradiation hole 103. A lower fixing unit 35, which is used for fixing the shell 11 of the capsule main body 10 to the receptacle 105 of the irradiation hole 103, is mounted to the shell 11 at a position under the lower end plug 31. As shown in FIG. 9a, the lower fixing unit 35 comprises a lower end cap 41, a rod tip 36, a stopper 38, and a stopper spring 40. The lower end cap 41 is mounted to the lower end plug 31, while the rod tip 36 is connected to the center of the lower end cap 41 and vertically extends downward. The stopper 38 is movably fitted over the rod tip 36, while the stopper spring 40 is fitted over the rod tip 36 at a position between the stopper 38 and the lower end cap 41, thus normally biasing the stopper 38 downward in a vertical direction. The rod tip 36 is a slim shaft, with two locking blades 37 formed on the lower portion of the rod tip 36 at diametrically opposite positions as shown in FIG. 9a. The rod tip 36 with the two locking blades 37 passes through the fixing slot 106 of the receptacle 105 provided at the bottom of the irradiation hole 103. The fixing slot 106 has two blade spaces allowing the two locking blades to pass through the fixing slot 106, and two locking recesses 106a are formed on the lower surface of the receptacle 105 such that the locking recesses 106a cross the locking slot 106 having the two blade spaces. The stopper 38 is provided with a plurality of holes 39 which allow the coolant flowing from the bottom of the irradiation hole 103 to smoothly flow upward through the stopper 38 without being disturbed by the stopper 38. The guide pins 38a are provided at the circumferential surface of the stopper 38 such that the guide pins 38a are bent outward in radial directions. The guide pins 38a thus come into contact with the inner surface of the irradiation hole 103 when the capsule main body 10 is installed in the irradiation hole 103. The upper ends of the guide pins 38a are connected to an annular ring 38b, thus being supported by the ring 38b, as best seen in FIG. 9b. That is, the lower fixing unit 35 of the capsule main body 10 according to the present invention reinforces the guide pins 38a by the annular ring 38b, so the lower fixing unit 35 effectively resists the torsion force applied thereto and effectively endures the stress caused by the torsion force even when the grapple head is rotated during the process of fixing the capsule main body 10 in the irradiation hole 103, different from a conventional lower fixing unit lacking such an annular ring, as shown in FIG. 9c. The process of assembling and installing the instrumented capsule 1 of the present invention and a material irradiation test performed with the capsule 1 will be described herein below. In order to fabricate the main body 10 of the instrumented capsule 1 for a material irradiation test, the heat media 13 with the specimens 2, lower fixing unit 35, lower end plug 31, insulators 23, reflectors 19, thermocouples 25, dosimeters 29, heaters 27, spacers 47 and 49, specimen compressing spring 43, upper end plug 33, and the guide spring unit 53 are set in or mounted to the shell 11, thus assembling the capsule main body 10. Thereafter, at the upper end plug 33 of the capsule main body 10, the vacuum control pipe 55 and the wiring pipes 57 for the control wires extending from the thermocouples 25 and the heaters 27 are inserted into the protection tube 60 so as to be air- and water-tightly guided to the junction box 80 through the protection tube 60 and the guide tube 70. The outside end of the guide tube 70 is connected to the guide tube connector 92 which is provided on the front surface of the junction box 80 installed at the upper portion of the reactor pool 100. In addition, at the rear surface of the junction box 80, the vacuum control pipe 55 and the control wires are separately connected to the associated parts of the capsule control system 90 through the several connectors provided at the rear surface of the junction box 80. The instrumented capsule 1 for the material irradiation test is thus completely installed in a research reactor. In other words, the protection tube 60 is connected at its inside end to the upper end plug 33, and at its outside end to the guide tube 70, thus guiding the vacuum control pipe 55 and the control wires to the guide tube 70. The outside end of the guide tube 70 is connected to the guide tube connector 72 provided at the front surface of the junction box 80, and so the vacuum control pipe 55 and the control wires are connected to the junction box 80. The vacuum control pipe 55 and the control wires are, thereafter, connected to the capsule control system 90 through the connectors provided at the rear surface of the junction box 80. Thereafter, the grab hook 83 of the capsule main body 10 is coupled to the overhead crane (not shown) positioned above the reactor pool 100, and primarily places the capsule main body 10 in the irradiation hole 103. Thereafter, the grapple head 84 is rotated to fix the capsule main body 10 in the irradiation hole 103 of the reactor pool 100. During the process of installing the capsule main body 10 in the irradiation hole 103 of the reactor pool 100, the lower fixing unit 35 provided at the lower end of the shell 11 is fixed to the receptacle 105 which is placed on the bottom of the irradiation hole 103 as shown in FIG. 11. During the process of fixing the lower fixing unit 35 to the receptacle 105, the receptacle 105 primarily catches the stopper 38 of the fixing unit 35. In such a case, only the rod tip 36 passes through the fixing slot 106 of the receptacle 105, while the stopper spring 40 is compressed by an external force. After the rod tip 36 completely passes through the slot 106 of the receptacle 105, the capsule main body 10 is rotated at an angle of 90xc2x0 by the grapple head 84 such that the two locking blades 37 of the rod tip 36 are positioned under the two locking recesses 106a of the receptacle 105. Thereafter, the external force is removed from the capsule main body 10, and so the stopper 38 is biased upward by both the liquid pressure of the coolant flowing upward from the position under the receptacle 105 and the restoring force of the stopper spring 38. The two locking blades 37 of the rod tip 36 are seated into the two locking recesses 106a of the receptacle 105. The installation of the capsule main body 10 in the irradiation hole 103 is accomplished. After the capsule main body 10 is completely loaded into the irradiation hole 103 as described above, the protection tube 60, placed in the coolant inside the reactor pool 100, is supported by a clamp robot arm 108. The instrumented capsule 1 is completely installed in the reactor pool 100. Thereafter, a desired material irradiation test using the capsule 1 is performed. During the material irradiation test, the specimens 2 housed in the shell 11 of the capsule main body 10 are irradiated. In such a case, the temperature inside the shell 11 is controlled by the thermocouples 25 and the heaters 27 wound around the spiral grooves 28 of the heat media 13, in addition to the helium gas atmosphere inside the shell 11. That is, the thermocouples 28 installed on the heat media 13 detect the temperatures of the specimens 2, and output temperature signals to the capsule control system 90. Upon receiving the temperature signals from the thermocouples 28, the capsule control system 90 controls the pressure of the helium gas flowing to the vacuum control pipe 55, thus controlling the heat transfer rate inside the shell 11 and controlling the output power of the heaters 27. For example, when the temperature of the specimens 2 is lower than a predetermined reference point or a predetermined target point, for example, 290xc2x0 C.xc2x110xc2x0 C., the degree of vacuum in the shell 11 is increased to reduce the quantity of heat transferred from the interior of the shell 11 to the coolant flowing around the shell 11 and the sheath-heaters 27 are operated to generate heat. In such a case, heat dissipated from the heaters 27 is uniformly transferred to the surfaces of the specimens 2 through the heat media 13 surrounding the specimens 2, thus increasing the temperature of the specimens 2 to a desired point. The dosimeters 29, installed around the specimens 2 in the heat media 13, detect and measure the quantity of neutron, radiation of the irradiated specimens 2. During such a material irradiation test in a research reactor, the capsule main body may interfere with adjacent structures due to its vibration caused by flow-induced vibration. Therefore, it is necessary to install the capsule in the research reactor in accordance with regulations defined by law. That is, the upper guide spring unit 53 is fitted over the upper end of the shell 11 as shown in FIGS. 2, 4a and 12, and comes into elastic and frictional contact with the inner surface of the irradiation hole 103 when the capsule main body 10 is installed in the irradiation hole 103. The upper guide spring unit 53 thus vertically places the shell 11 of the main body 10 at the center of the vertical irradiation hole 103 inside, and prevents the shell 11 from being unexpectedly eccentrically placed in the irradiation hole 103. The desired structural integrity of the capsule main body 10 is thus maintained. The lower fixing unit 35 provided at the lower end of the capsule main body 10 firmly fixes the capsule main body 10 in the vertical irradiation hole 103. When loading the instrumented capsule 1 of the present invention in an irradiation hole 103 of a reactor pool 100, the grab hook 83 provided at the upper end of the capsule main body 10 is coupled to an overhead crane, and is moved to a desired position above the reactor pool 100 by the crane. Thereafter, the grapple head 84 of the capsule main body 10 is connected to an appropriate tool (not shown), and is rotated by the tool so as to fix the capsule main body 10 to the receptacle 105 provided at the bottom of the irradiation hole 103. In the instrumented capsule 1 of the present invention, the guide pins 38a are reinforced by the annular ring 38b which supports the upper ends of the guide pins 38a as shown in FIGS. 9b and 10. The present invention thus allows the guide pins 38a, which have been recognized as the most easily breakable parts in the case of conventional instrumented capsules, to have a stable structure capable of effectively resisting both a tensile load applied to the guide pins 38a in an axial direction of the capsule main body 10 and a bending load applied to the guide pins 38a in a transverse direction of the capsule main body 10. As described above, the present invention provides an instrumented capsule for material irradiation tests in research reactors. In the instrumented capsule of the present invention, specimens are housed in the shell of a capsule main body such that the specimens create a multi-staged specimen arrangement. The temperature of the specimens during a material irradiation test is detected by thermocouples, and is controlled by heaters, spirally wound around the external surfaces of the heat media, in accordance with the detected results. In addition, the temperature of the specimens during the material irradiation test is also indirectly controlled by controlling the heat transfer rate inside the shell. In such a case, the heat transfer rate inside the shell is controlled by controlling pressure of the helium gas atmosphere in the shell. Therefore, it is easy to control the temperature of the specimens housed in the shell of the capsule main body, so the capsule of the present invention performs an optimum material irradiation test. In the capsule of the present invention, the vacuum control pipe and several control wires extending from the heaters and thermocouples are connected to the capsule control system through a junction box. The junction box of the present invention has a small size and light weight, different from conventional junction units, so it is easy and convenient for workers to handle the junction box. During a material irradiation test in a research reactor, the capsule main body may interfere with adjacent structures due to its vibration caused by flow-induced vibration. In order to prevent such interference of the capsule main body with adjacent structure, an upper guide spring unit is fitted over the upper end of the shell such that the guide spring unit comes into elastic and frictional contact with the inner surface of the irradiation hole when the capsule main body is loaded into the irradiation hole. The upper guide spring unit thus vertically places the capsule main body at the center of the vertical irradiation hole inside, and prevents the capsule main body from being unexpectedly and eccentrically placed in the irradiation hole. Desired structural integrity of the capsule main body is thus maintained. In the instrumented capsule, the guide pins, provided at the lower end of the capsule main body, are reinforced by an annular ring, thus having a stable structure, different from conventional guide pins which have been recognized as the most easily breakable parts of instrumented capsules. The guide pins thus more effectively endure a tensile load and a bending load during the process of loading/unloading the capsule main body. Although a preferred embodiment of the present invention has been described for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.
047215976	description	DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, a typical fuel rod assembly 10 includes individual fuel rods 11 (64 rods are shown in FIG. 1), guide rods 13 and a handle member 14. The individual fuel rods (sometimes also called fuel pins) 11 are about 0.4-0.6 inch in diameter and about eight feet long in one type of nuclear reactor installation and the fuel rods are about 15 feet long in another type of nuclear reactor installation. The fuel rod assembly 10 is withdrawn from a nuclear reactor after the nuclear fuel within the fuel rods 11 has been spent. Thereafter, the fuel rod assembly 10 is stored in appropriate storage racks under water in storage pools until its activity is dissipated. The purpose of the present invention is to compact the fuel rods 11 after their activity has dissipated and to store the fuel rods in a new and different container wherein their spacing is altered. The fuel rods as presented in a fuel rod assembly for use in a nuclear reactor are intended to be active in the presence of slow neutrons. The fuel rods in operation are spaced apart by predetermined distances so that released neutrons can be slowed to an effective velocity for atomic reactions. Water is an effective moderator for this purpose. As the fuel rods are brought closer together, there is insufficient water between fuel rods to retard the velocity of the neutrons. Hence the reactivity of the fuel rod assembly is reduced because the high velocity neutrons pass through the installation without sufficient retardation to cause any significant atomic collisions. Thus the reactivity is reduced as the fuel rods are brought together. As shown in FIG. 2, a fuel rod assembly 10 initially has its upper end removed so that the top ends 15 of the individual fuel rods 11 are exposed. The upper end of the fuel assembly is removed by cutting or otherwise. One way of removing the upper end is to cut the top elements with an air-powered underwater band saw. In some fuel rod assemblies, the upper end may be dismantled by removing the bolts of other fastening devices which connect it to the main frame. After the upper end of the assembly is removed, the top ends 15 of the individual fuel rods 11 are exposed as shown in FIG. 2. As shown in FIG. 3 the spaced-apart pattern of fuel rods forms a rectangular array of fuel rods within the fuel rod assembly. Above the fuel rod assembly 10 is a transition funnel 20 which has a lower end 21 and an upper end 22. The lower end 21 as shown in FIG. 4 has a generally square grid corresponding to the cross-section of the fuel rods 11, as shown in FIG. 3. At the lower end 21 is a grid 23 having openings for individual tubes 24 corresponding in number and array with the top ends 15 of the fuel rods. The transition funnel tapers from its lower end 21 toward its upper end 22. At the upper end 22, the transition funnel 20 as shown in FIG. 5, has a grid 25 with openings for receiving the top ends of the tubes 24 in a desired array. It will be observed that the array of the tube openings 24 in the grid 25 is equilateral triangular--a preferred array. Above the transition funnel 20 is a container 30 having outer dimensions corresponding to the outer dimensions of the fuel rod assembly 10. The container 30 preferably is a metal rectangular box having a length slightly greater than the length of the fuel rods 11 and having sufficient cross-sectional area to receive the compacted fuel rods from a fuel rod assembly 10 in approximately half of its cross-sectional area. In one embodiment, a vertical baffle is provided to divide the container 30 into parallel chambers 32, 34. All of the fuel rods 11 from the fuel rod assembly 10 can be confined in the chamber 32 as shown in FIG. 2. All of the fuel rods from another fuel rod assembly can be confined in the chamber 34. Extending downwardly through the container 30 is a number of individual pulling elements 40 corresponding to the number of fuel rods 11 in the fuel rod assembly 10. The individual pulling elements are connected at their upper ends to a header device 41 which is, in turn, connected by a cable to a distantly located tensioning device 42 such as a tensioning reel or wrench for tensioning the entire group of pulling elements 40. The lengths of the pulling elements are sufficiently long so that they can be lowered by operation of the tensioning device to extend through the chamber 32 and enter, one each, into one of the tubes 24 within the transition funnel 20. Continued lowering of the pulling elements causes their ends to extend through the grid 23 at the bottom of the transition funnel 20 and thence into abutting, end-to-end positions with the fuel rods such that contact is made between the end of each pulling element and a fuel rod aligned therewith. As shown in FIG. 6, the pulling elements each include a tube 43 comprised of plastic material. A tubular fitting 44 is provided with a threaded shank 45 for threaded engagement in the lower end of the tube. The threaded shank terminates at a torque-receiving section 46 which is constructed with a hexagonally-shaped outer wall for use to thread the shank 45 in the tube 43. Extending from the torque-receiving section 46 is a tubular holder 47 having an annular recess 48 in the outer wall surface about midway along the length of the annular wall. A cap 49 includes an end wall 50 integral with an annular wall 51 which can slide over the end portion of the tubular holder 47 and retained thereon by elastic deformation of the annular wall 51 so that a portion protrudes into the annular recess 48. The annular wall 51 of the cap near the end wall 50 is provided with radial openings 52 to permit a flow of an inert gas, e.g., argon, which is conducted by the tube 43 through an insulator sleeve 53 made of electrically insulative material such as glass into the cap at the end wall thereof where an arc is struck by electrical current delivered to an electrode 54. The electrode has a conical end which is spaced by a predetermined distance from the end wall 50 in the cap. The flow of inert gas prevents erosion, particularly oxidation, of the electrode which is made from metal, for example, tungsten. The electrode is connected to a holder 55 that includes a collet that is forced into engagement with the electrode by a sleeve 56 which is threaded onto the holder. Extending from the holder upwardly along the tube is a wire 57 for delivering electric current to the electrode. The gap which is established between the tip of the electrode and the cap is established by an anchor pin 58 preferably comprised of plastic or some other non-electrically conductive material through the side wall of the tube and into a suitable opening provided in the holder. Also shown in FIG. 6, at the upper end of the tube 43, there is a header 59 through which the upper ends of each tube 43 pass. Passageways 60 are formed in the header by drilling or other suitable operations. The passageways extend through the side wall of the tube for delivering the inert gas into the interior of the tube. The illustration in FIG. 6 is typical of the arrangement provided for the array of tubes. A plug 61 is fitted into the upper end of each of the tubes 43 to seal the end of the tubes so that the inert gas which is fed into the interior tube flows in a direction of the tube's length toward the electrode 54. The electrical wire 57 which extends from the electrode along the tube is passed through a suitable opening the plug 61 in a gas sealed manner. The end portion of the wire extending from the cap is connected to a suitable power supply 63 that is controlled so that electrical current is delivered to the electrode for a period of time sufficient to effect welding of the cap to a fuel rod. Preferably, the welder which is incorporated in the lower end of each tube 43 is a TIG welder which functions by striking an arc with the end wall 50 of the cap. The arc is submerged in the inert gas, e.g., argon, which is conducted by the tube to prevent erosion, particularly oxidation, of the electrode tip. The arc creates a pool of molten metal in the cap which welds the cap to the top of the fuel rod. The electrical current is delivered for about 4 to 6 seconds at about 80 amps to strike an arc is generated sufficient heat to weld the cap 49 to the top end 15 of a fuel rod. In FIG. 6, the top end 15 of the fuel rod is illustrated in a position which is suitable for carrying out the welding process. The operator, employing remote control devices, controls the welders in the ends of each pulling element for welding a corresponding fuel rod upper end 15. After all of the caps on the ends of the pull elements have been welded to fuel rods, the tensioning device 42 is activated and the pull elements 40 are drawn upwardly through the transition funnel 20 and the chamber 32. Each of the fuel rods 11 is withdrawn from the fuel rod assembly 10 upwardly through an individual tube 24 and into an altered array, preferably an equilateral triangular array as shown in FIG. 5. The fuel rods 11 preferably are drawn at a rate such that their upper ends 15 enter into the chamber 32 concurrently whereby compacted nesting of the fuel rods 11 is readily achieved within the chamber 32. Because the fuel rods 11 are in tension, no Hertzian stresses are imposed on the rods during the consolidation process. Any preexisting bends in a rod can be removed by straightening the fuel rods as they pass through the tubes in chamber 32 even though a bent fuel rod has been embrittled due to irradiation. The tension on each fuel rod required for withdrawal is from about 20 to 200 pounds. After the pulling elements 40 have been withdrawn to the top 33 of the container 30, the individual pulling elements are separated from the fuel rods 11. For this purpose, a guillotine shear can be arranged so that the shear blade is brought into contact with the weld sites between the cap and the fuel rod. Alternatively, the tubular fitting 44 can be pulled from the cap 49 whereby the latter will remain with the stored fuel rods. The chamber 32 is thereafter filled with fuel rods in a compact array. The fuel rod assembly 10 no longer contains fuel rods 11 and can be withdrawn from the water pool for storage and ultimate disposal in an appropriate fashion. The container 30 is subsequently advanced to another fuel rod assembly along with the transition funnel 20. The pulling elements 40 are introduced through the alternate chamber 34 and the transition funnel 20. The process is repeated and the alternate chamber 34 is filled with fuel rods. The container 30, holding fuel rods in a compacted array, can be stored under water in the water storage pool in the same type storage rack which formerly housed the fuel rod assembly 10. The storage capacity of a water storage pool can be nearly doubled by practicing this method. The precise construction of the transition funnel 20 is such that the tubes 24 merge from the lower end 21 to the upper end 22. As the fuel rods are drawn upwardly through the tubes 24, the fuel rods cannot increase their rod-to-rod spacing but, instead, are merged into an ever-increasing density whereby the reactivity of the array is continuously reduced. Thus the possibility of developing a critical spacing of the fuel rods is precluded throughout the controlled densifying operation. Although the invention has been shown in connection with a certain specific embodiment, it will be readily apparent to those skilled in the art that various changed in form and arrangement of parts may be made to suit requirements without departing from the spirit and scope of the invention.
	description	The presently preferred method for remediating radioactive waste is illustrated in FIG. 1. The present invention is presently directed to non-homogeneous, multi-component waste typically stored in underground tanks. The tank waste may include liquid and solid/sludge low activity waste (LAW) as well as solid/sludge high level waste (HLW). The HLW may include low boiling organic material, volatile metals, and heavy metal/transuranic components. Due to the high levels of radiation generated by the HLW, the vitrification technology is required to be placed in shielded cells that isolate the waste from the operating staff. The operation and control of the system, replacement of instrumentation, manipulation of the waste, and any necessary maintenance are performed using robotic devices. In a preferred embodiment, the waste is hydraulically removed from the tanks or other storage areas and the LAW liquids are decanted from the LAW/HLW solids/sludge. The solid/sludge waste is then isolated in a thermal desorption-type reaction vessel of the type disclosed herein. The reaction vessel is then flushed with an inert gas to provide an inert atmosphere. Presently preferred is argon or helium, but any suitable inert gas may be utilized. The pressure in the reaction vessel is then reduced, preferably to about 0.1 atm. The inert atmosphere in combination with the reduced pressure act to limit or eliminate explosive reactions of the waste as the temperature is raised. Removal of Organic Material The temperature in the reaction vessel is then raised to a first temperature necessary to vaporize the low boiling organic components. The temperature is dependent on the specific components of the waste, but it is anticipated to be about 30-40xc2x0 C. at 0.1 atm. This first temperature is maintained until essentially all of the organic material has been vaporized. The gaseous organic components are then removed from the reaction vessel for off-gas treatment. The treatment of the gaseous organic components may be accomplished by any method that results in a product that meets federal regulatory compliance standards. Presently preferred is catalytically oxidizing the organic components to form carbon dioxide and hydrogen halides, and then scrubbing the carbon dioxide and hydrogen halides through sodium hydroxide to form sodium halide and sodium carbonate for on-site disposal in an Emergency Response Disposal Facility (ERDF) landfill. Sample reactions for this step of the process follow: CxHyClxe2x86x92xc3x97CO2+H2O+HCl 3NaOH+HCl+CO2xe2x86x92Na2CO3+NaCl+2H2O This initial temperature phase process reduces the total waste volume by about three percent, based on a typical tank waste composition. Removal of Volatile Metals and Water The temperature in the reaction vessel is then raised to a second temperature necessary to vaporize the volatile metals components, about 50-60xc2x0 C. at 0.1 atm. This waste typically includes mercury, arsenic, selenium, and zinc. Any water in the waste will be vaporized at this time. The second temperature is maintained until essentially all of the volatile metals are vaporized. The gaseous volatile metals components are then removed from the reaction vessel for off-gas treatment. The water vapor containing the volatile metals is collected in a conventional condenser. The treatment of the gaseous volatile metal components may be accomplished by any method that results in a product that meets federal regulatory compliance standards for disposal. Presently preferred is the removal of the water to concentrate the metal ion solution by reverse osmosis through polymeric reverse osmosis membrane, preferably a high pressure high rejection polyamide thin membrane with a molecular cut off of approximately 50. The preferred reverse osmosis unit was constructed by and purchased from Osmonics, Inc., utilizing an OSMONICS(copyright) Desal Membrane. The metal ion solution is dried and the volatile metal ions are then grouted by a conventional method or as presently preferred, immobilized in a radiation shielding polymer which is the subject of the applicant""s pending application Ser. No. 09/775,359. The applicant""s polymer is a urethane-based composition, composite, or blend. The composition is formed by mixing a liquid isocyanate monomer and a liquid phenolic resin with a phosphate ester flame retardant at room temperature until a homogeneous mixture is formed. Presently preferred is 25 to 75% diphenylmethane 4,4xe2x80x2-diisocyanate monomer, with 40% most preferred, and 20 to 70% phenol formaldehyde resin with 53.85 to 54% most preferred. The presently preferred flame retardant is a halogenated phosphate ester, 3 to 10% with 6% most preferred. The resulting composition cures without heating in approximately 6-18 hours depending on environmental conditions. A catalyst may be utilized in applications where a short curing time is necessary. Phenylpropyl pyridine, 0 to 1%, 0 to 0.15% most preferred, is presently used as a catalyst, reducing the composition cure time to about 20 minutes, depending on environmental conditions. A ratio of 16% polymer to 84% volatile metal ion waste is presently preferred. The grouted waste is suitable for storage in an ERDF landfill. The second temperature phase process reduces the total waste volume by about sixty-one percent, based on a typical tank waste composition. Removal of Nitrates, Sulfur and Chromium The temperature in the reaction vessel is then raised to a third temperature at which pyrolysis of the remaining waste, primarily heavy metal/transuranics, occurs. Pyrolysis results in the formation of gaseous nitrogen and sulfur oxides and chromium, and leaves a metal oxide ash residue. This residue includes all of the non-volatile constituents including substantial sodium salts. The gaseous components are removed from the reaction vessel for off gas treatment. Presently preferred is scrubbing the gas through sodium hydroxide, phosphoric acid and calcium chloride to produce sodium sulfate, ammonium phosphate, and calcium chromate, respectively, for disposal in an ERDF landfill. Sample reactions for the step above follow: xe2x80x833NH3+H3PO4xe2x86x92(NH4)3PO4+3H2O xe2x80x832SO2+2NaOHxe2x86x92Na2SO4 xe2x80x83CrO2Cl2+Ca(OH)2xe2x86x92CaCrO4+2HCl C=Catalyst, R=Reagent=N2H5Cl The third temperature phase of this process results in an additional twenty percent volume reduction of the tank waste. At this point, only about ⅙ to {fraction (1/7)} of the original sludge mass and volume remain. Removal of Transuranic Oxides The metal oxide ash is then removed from the reaction vessel for treatment. The following procedure for producing products that meet federal regulatory compliance standards is presently preferred. The metal oxides are washed with water to remove all of the sodium and any water-soluble metal oxides, including sodium, strontium, technetium and cesium. While these components have fairly high solubility in water at room temperature, the temperature of the wash can be raised to insure dissolution. The LAW liquids decanted from the tanks or other storage areas before the waste was placed in the reaction vessel can be added to the wash solution for treatment. The wash solution is centrifuged to remove any solids. Carbon dioxide is then bubbled through the clear liquid wash solution to precipitate the strontium as strontium carbonate, and a 1% hydrazine hydrate solution is added to reduce the technetium from Tc+7 to Tc+3. The wash solution is then decanted from the precipitate, and the precipitate is added to the removed solids and dried for disposal by vitrification. The clean oxides are mixed with stoichiometric quantities of boron and silicon dioxide to yield high quality borosilicate glass with excellent long-term durability and leaching characteristics. It is preferred to filter the solids from the wash prior to the addition of carbon dioxide, as any resultant change in pH may cause plutonium oxide to go into solution. The decanted solution is then repeatedly diluted and subjected to reverse osmosis under 800 psi until the retentate is essentially sodium free, through a polymeric nanofiltration membrane. Presently preferred are three cycles of dilution/reverse osmosis, with the retentate being diluted by a factor of 9:1 deionized water to retentate for each cycle. The sodium is then recovered by drying the filtrate solution. The sodium is disposed of as sodium carbonate. In the alternative, the sodium can be vitrified into sodium aluminum silicate glass. The retentate solution then flows through a column packed with a zeolite for ionexchange recovery of the cesium and technetium. Presently preferred is a combination of zeolite material including TSM-140 and clinoptilolite by Steelhead Specialty Minerals, Spokane, Washington and Zeolyst Intl., Valley Forge, Pa. Once the ion exchange is complete, or the zeolite material has been exhausted, the zeolite containing the metal ions is removed from the column and dried. The stream of sodium solution that is produced is dried for disposal. Two alternatives for disposal are currently preferred, the first being vitrification into sodium aluminum silicate glass, the second being on site disposal. The dried, sodium free metal ions contained in the zeolite, plus the insoluble metal oxides and precipitate removed earlier is then mixed and melted with boron and silicon dioxide to fabricate borosilicate glass monoliths. The HLW sludge/solid fraction going to the melter has been significantly reduced to nearly {fraction (1/10)} of its original mass and volume. It is currently anticipated that the 60-65%(by volume) liquid fraction undergoes a 90-95% volume/mass reduction due to the loss of water during processing. The corresponding 35-40%(by volume) solid fraction undergoes an 84% volume/mass reduction. Referring to FIG. 2, there is illustrated a preferred embodiment of a thermal desorptiontype unit 10 constructed of a suitable material such as stainless steel and shielded to prevent leakage of radiation. The unit 10 includes a lid portion 12 and a cylindrical body portion 14. The body portion 14 is a double walled reaction vessel including an inner liner 16 and an outer shell 18. The inner liner 16 and outer shell 18 are held in place relative to each other by support brackets 19 or any other suitable means to form a void 24 therebetween. The inner liner 16 defines the storage compartment 17 of the unit 10. The lid portion 12 includes an aperture or inlet 20 having a cover 22 to allow the radioactive waste to be introduced into the storage compartment 17 of the body portion 14. The unit 10 further includes temperature control system 26 which is operatively connected to heating elements 28 located in the void 24, and temperature sensors 30 located adjacent the inner liner 16 within the compartment 17. The temperature control system 26 is capable of raising the temperature within the compartment 17 to any desired temperature between room temperature and pyrolysis temperatures. A pressure control system 32 includes a vacuum pump 34 that is adapted to lower the pressure within the compartment 17 to about 0.1 atmosphere. The system 32 includes at least one pressure sensor 36 located within the compartment 17. The body 14 further includes at least one gas outlet. In the presently preferred embodiment, an outlet 37 leads to three gas outlets 38, 40 and 42 as illustrated. These outlets correspond to three gaseous waste fractions that are typically generated by the method of the present invention. They include an outlet 38 for gaseous low boiling organic material, outlet 40 for gaseous volatile metals and outlet 42 for gaseous nitrogen oxides. In an alternative embodiment, the gaseous waste can all be removed through separate multiple outlets in the body 14, one outlet for gaseous low boiling organic material, one outlet for gaseous volatile metals, and one outlet for gaseous nitrogen oxides. The body 14 also includes at least one solid waste outlet. In one preferred embodiment, a hinged portion 44 is attached to the lower portion of the body 14 by a hinge 46 and is kept closed during heating by latch 48. When opened, any metal oxide ash remaining after pyrolysis can be dumped and removed from the unit 10 for further processing Since thermal desorption is performed at a pre-determined and carefully controlled ramp of various combinations of temperatures and pressures, it is recognized and anticipated that the control of such temperatures and pressures within the unit 10 can be electronically controlled via appropriate means so as to automatically control the various temperatures and pressures from start to finish. Electronic control of the unit 10 can be accomplished in a wide variety of different ways such as by coupling an electronic controller or other computer or processing means 50 to the temperature control system 26 and the pressure control system 32, the controller 50 being capable of controlling and adjusting the various temperatures and pressures within the unit 10 for completing the process. Electronic controllers such as the controller 50 are commonly used in association with a wide variety of different types of devices for accomplishing various tasks. In this regard, controller 50 may include processing means such as a microcontroller or microprocessor, associated electronic circuitry such as input/output circuitry, analog circuits and/or programmed logic arrays, as well as associated memory. Controller 50 can therefore be programmed to sense and recognize the appropriate signals indicative of the various conditions and states associated with unit 10 such as signals from sensors 30 and 36 indicative of the temperatures and pressures inside the compartment 17. In this regard, controller 50 could be operatively connected via conductive paths 52 and 54 for receiving input signals from temperature control system 26 and pressure control system 32 such as from the respective temperature and pressure sensors associated therewith. Based upon input signals 52 and 54, controller 50 would be configured to output appropriate signals such as output signals 56 and 58 to the appropriate control mechanisms such as control systems 26 and 32 to accurately control and change the temperatures and pressures associated with unit 10 during the thermal desorption process. Based upon the various parameters inputted to controller 50, appropriate calibration tables, charts, maps and other data can be stored or programmed within the memory of controller 50 so as to control and/or change the temperature, pressure and other selected parameters associated with compartment 17 so as to achieve the stated goals and objectives of the remediation process. Still other control systems for accomplishing the above-described processes can be utilized without the departing from the spirit and scope of the present invention. The unit 10 also includes a gas purging or venting system 60 operatively connected to the unit 10 in a known manner to allow for the removal of ambient air from the compartment 17 and the introduction of an inert gas atmosphere therewithin. The system 60 functions to flush the compartment 17 with an inert gas to provide the inert atmosphere. Although argon or helium is generally preferred, any suitable inert gas may be utilized. Once the inert gas atmosphere is established, the pressure within compartment 17 is then reduced, preferably to about 0.1 atm as previously described. The inert atmosphere in combination with the reduced pressure act to limit or eliminate explosive reactions of the waste within compartment 17 as the temperature is raised therewithin to accomplish the present remediation process. LAW and HLW simulants were prepared according to the procedure provided by the Tank Focus Group as approved by the Department of Energy (DOE) for use in each of the following examples. The simulants were thoroughly mixed for several hours using magnetic stirrers and let stand overnight. Both simulants yielded about 60-65% by volume clear solutions and about 40-35% by volume heavier sludge. The clear liquids from both simulants were decanted, filtered through a Buchner funnel and stored. The clear decanted liquids and the remaining solids/sludge were chemically analyzed after proper acid digestion procedures and by Atomic Absorption/inductively Coupled Plasma (AA/ICP) techniques to verify the simulant components. Aliquots of the clear liquid samples were dried at 105xc2x0 C. overnight. The volume decrease, due to loss of water, was determined to be about 90-95%. The samples were then subjected to pyrolysis at about 900xc2x0 C., at ambient pressure. The samples were cooled and the remaining ash was evaluated to determine volume reduction. The results are shown in Tables 1 and 2 which are set forth in FIGS. 3 and 4. An aliquot of the clear LAW solution was subjected to reverse osmosis through a high rejection polyamide thin membrane, OSMONICS(copyright) Desal Membrane by Osmonics, Inc. under 800 psi. The retentate was then diluted 9:1 deionized water to retentate, and the reverse osmosis repeated. A third cycle of reverse osmosis/dilution resulted in a retentate solution in which sodium was not detected. The sodium solution (the filtrate) was evaporated in a glass tray using an infrared heat source. The sodium residue was weighed and its specific gravity was determined to be 2.130 gms/cc, confirming purity of the sodium. The solution containing the cesium and strontium was evaporated to dryness, the residue weighed and grouted with the applicant""s polymer composition. The resulting monoliths were subjected to ANS 16.1 leaching tests. The results can be seen in Table 3 which is set forth in FIG. 5. An aliquot of the clear LAW filtrate was subjected to the reverse osmosis/diafiltration method described above until no sodium was detected in the retentate solution. The sodium free solution was then subjected to ion exchange using a column packed with natural and synthetic zeolites. The zeolites quantitatively exchanged sodium ions for every equivalent of cesium and strontium ions. The zeolites utilized were clinoptilolite by Steelhead Specialty Minerals, Spokane, Washington, and Zeolyst Intl., Valley Forge, Pa. The column heights were 5 inches with a 1.5 inch diameter. The flow rate was 2 ml/min. The solution was passed through a second identical column and the effluent saline solution was tested for cesium and strontium. The saline solution was then evaporated to dryness. The zeolite column packing was removed, dried, and grouted 84:16 waste to polymer with applicant""s polymer composite. The grout was cured in a cylindrical mold for 18 hours, and then was subjected to ANS 16.1 leaching tests for 28 days. The results can be seen in Table 4 which is set forth in FIG. 6. The volume reduction from the clear liquids to the polymer grout was on the order of 60-90%. The solid residue from the LAW waste was washed several times with water to remove sodium from the residue, and the residue centrifuged. The centrifugate was analyzed by AA to verify sodium was removed from the residue. A known quantity of the sodium free sludge was subjected to thermal desorption followed by pyrolysis. Two samples were taken from the ash residue and made into a polymer based grout and several grams of borosilicate glass. The glass monoliths were generated by heating the oxide residue with stoichiometric amounts of boron and silicon dioxide in an appropriate crucible in an electric furnace around 1,600 to 1700xc2x0 C. to form cylindrically shaped monoliths, 3 cm in height, 1 cm in diameter. in an electrical furnace around 1800xc2x0 C. Both samples were subjected to ANS 16.1 leaching tests. The results can be seen in Tables 5 and 6 which are set forth in FIGS. 7 and 8. The HLW simulant was also separated as clear liquid and heavy sludge and were subjected to similar evaluation as that of the LAW simulant. The results can be seen in Tables 7 through 9 which are set forth in FIGS. 9-11. From the foregoing description, those skilled in the art will appreciate that all the objects of the present invention are realized. A radioactive waste remediation method that results in a significant reduction in the total volume/mass of waste is provided. The volume/mass reduction that ranges from about 75.5% to 84.7% greatly reduces disposal and storage costs. There is further provided a method that allows the waste to be pumped straight from an underground waste tank or other storage areas without costly and time consuming pretreatment steps, thereby reducing costs while limiting handling and employee exposure. In addition, the method of the present invention provides a simplified and streamlined process that provides improved separation while being easily adapted to handle variations in tank waste. Finally an apparatus that is especially well suited to perform the method of the present invention is disclosed. While specific embodiments have been shown and described, many variations are possible. Most importantly, while the preferred embodiment is described as it relates to tank waste, this method is applicable to any multi-component waste product, radioactive or not. While a preferred embodiment of the waste remediation method of the present invention is described in relation to the thermal desorption-type apparatus illustrated in FIG. 2, the method is not limited to the apparatus disclosed and claimed herein. The steps of the present method may be accomplished in any suitable reaction vessel, or the steps may be accomplished in more than one reaction vessel. In addition, the off-gas treatments described, while presently preferred, are not meant to be limiting. Any suitable off-gas treatment may be utilized. Thus there have been shown and described embodiments of a method and apparatus for remediating radioactive waste, which method and apparatus fulfill all of the objects and advantages sought therefore. As evident from the foregoing description, certain aspects of the present invention are not limited by the particular details of the examples illustrated herein, and it is therefore contemplated that many changes, modifications, variations and other uses and applications of the present invention, including equivalents thereof, will become apparent to those skilled in the art after considering this specification and the accompanying figures. All such changes, modifications, variations and other uses and applications which do not depart from the spirit and scope of the invention are deemed to be covered by the invention which is limited only by the claims which follow.
	summary
	abstract	Disclosed is a shielding system for customized shielding of a patient or an operator from X-rays generated by a gantry. The shielding system is mounted on the gantry. The system has a rail that is arcuately movable in relation to gantry-mounted foundational blocks with apertures that receive movable rails from which protective curtains are suspended.
	description	The present invention relates to a nuclear fuel assembly spacer grid defining a lattice of cells for receiving fuel rods. A boiling water reactor nuclear fuel assembly (or “BWR fuel assembly”) generally comprises a bundle of fuel rods maintained laterally by spacer grids distributed along the bundle of fuel rods, at least one tubular water channel provided within the bundle of fuel rods for channeling a flow of coolant/moderator separately from the fuel rods and a tubular fuel channel encasing the bundle of fuel rods for channeling a flow of coolant/moderator between and about the fuel rods. Similarly, a water-water energetic reactor nuclear fuel assembly (or “VVER fuel assembly”) generally comprises a bundle of fuel rods maintained laterally by spacer grids distributed along the bundle of fuel rods, at least one water rod provided within the bundle of fuel rods for channeling a flow of coolant/moderator separately from the fuel rods and a tubular fuel channel encasing the bundle of fuel rods for channeling a flow of coolant/moderator between and about the fuel rods. A spacer grid generally defines a lattice of cells for receiving fuel rods and comprises a peripheral band composed of peripheral strips and delimiting the peripheral contour of the spacer grid. It preferably comprises positioning means provided on the peripheral band for ensuring an adequate lateral positioning of the spacer grid inside the fuel channel for ensuring an adequate flow of coolant/moderator between and about the fuel rods, namely about the peripheral fuel rods located adjacent to the inner walls of the fuel channel. US 2005/0246961, EP 0 709 0857 and U.S. Pat. No. 6,156,043 disclose spacer grids comprising a peripheral band provided with rigid tabs, lobs or stops protruding outwardly from the outer periphery of the peripheral band and formed in the peripheral band and/or assembled to the peripheral band. An object of the invention is to provide a nuclear fuel assembly spacer grid allowing good lateral positioning of the bundle of fuel rods within the fuel channel, while being obtainable easily and at low cost. To this end, a nuclear fuel assembly spacer grid defining a lattice of cells for receiving fuel rods is provided, wherein the spacer grid comprises a peripheral band composed of at least one peripheral strip delimiting a portion of the peripheral contour of the spacer grid, and at least one spacer grid positioning spring elastically deformable and formed in the peripheral band. In other embodiments, the spacer grid comprises one or several of the following features, taken in isolation or in any technically feasible combination: the at least one spring is cantilevered; the at least one spring is stamped in the peripheral band; the at least one spring is delimited in the peripheral band by at least one elongated slot cut in the peripheral band; the at least one elongated slot is a curved slot; the at least one spring comprises a flexible cantilevered tab and a rigid contact projection protruding outwardly from the tab; the at least one spring is adjacent to a longitudinal end of one of the at least one peripheral strip; two springs are formed in one of the at least one peripheral strip each adjacent to a respective longitudinal end of the peripheral strip; the peripheral band is composed of several peripheral strips each delimiting a side of the peripheral contour of the spacer grid and each comprising two springs each adjacent to a respective longitudinal end of the corresponding peripheral strip; one spring is formed by one free cantilevered end portion of the peripheral band; one corner cell is delimited by two peripheral strip free end portions of two peripheral strips of the peripheral band delimiting two adjacent sides of the peripheral contour of the spacer grid, said free end portions being separated from each other by an aperture such that the or each cell corner is laterally opened; each corner cell is delimited by two free end portions of two adjacent peripheral strips separated by an aperture; each free end portion delimiting a laterally opened corner cell forms a spacer grid positioning spring; one motion limiter associated to the at least one spring and formed in the peripheral band adjacent to the at least one spring and protruding outwardly; an assembly of interlaced strips comprising intersecting sets of peripheral strips and intermediate strips distributed between the peripheral strips. The a nuclear fuel assembly is also provided comprising a bundle of fuel rods, a fuel channel and at least one spacer grid as defined above for laterally positioning the bundle of fuel rods within the fuel channel. The nuclear fuel assembly 2 for boiling water reactor illustrated on FIG. 1 is elongated along an assembly axis L extending vertically when the fuel assembly is disposed inside a nuclear reactor. The fuel assembly 2 comprises a bundle of nuclear fuel rods 4, a tubular water channel 6 arranged within the bundle of fuel rods 4, spacer grids 8 distributed along the bundle of fuel rods 4 and maintaining the fuel rods laterally, and a tubular fuel channel 10 surrounding the bundle of fuel rods 4. The fuel rods 4 are elongated and extend parallel to each other along the assembly axis L. Each fuel rod 4 comprises a tubular cladding, pellets of nuclear fuel stacked inside the cladding and caps closing the ends of the cladding. The fuel rods 4 are arranged in a lattice with a interspacing between the fuel rods 4. The water channel 6 extends parallel to the fuel rods 4. The water channel 6 is arranged for channeling a coolant/moderator flow separately from interspaces between the fuel rods 4. The water channel 6 typically replaces one or several fuel rods 4 in the lattice. The spacer grids 8 are distributed in space relationship along the fuel rods 4. Each spacer grid 8 extends transversally to the assembly axis L. Each spacer grid 8 defines a lattice of cells 16 each for generally receiving a fuel rod 4 and an opening 18 for receiving the water channel 6. The fuel rods 4 are maintained laterally by each of the spacer grids 8. The water channel 6 passes through the corresponding opening 18 of the spacer grids 8. Each spacer grid 8 is secured to the water channel 6. The fuel channel 10 extends parallel to the fuel rods 4. The fuel channel 10 encases the bundle of fuel rods 4 and the water channel 6. The fuel channel 10 is arranged for channeling a coolant/moderator flow between and about the fuel rods 4. The fuel assembly 2 typically comprises a lower nozzle and an upper nozzle spaced along assembly axis L, the fuel rods 4, the water channel 6 and the fuel channel 10 extending between the lower nozzle and the upper nozzle, with the water channel 6 and the fuel channel 10 connecting the lower nozzle and the upper nozzle. In operation, the fuel assembly 2 is placed in a nuclear reactor with the assembly axis L being substantially vertical and the lower nozzle partly inserted into a coolant/moderator outlet provided in a bottom plate of the reactor. A coolant/moderator flow exiting the outlet flows into the lower nozzle and splits into a first coolant/moderator flow flowing in the water channel 6 separately from the fuel rods 4 and a second coolant/moderator flow flowing in the fuel channel 10 between and around the fuel rods 4. The spacer grids 8 may be similar. One spacer grid 8 according to the invention will be further described in reference to FIGS. 2-4. FIG. 2 illustrates the spacer grid 8 received in the fuel channel 10, without the fuel rods and the water channel for the sake of clarity. As illustrated on FIG. 2, the spacer grid 8 exhibits a square peripheral contour. The spacer grid 8 comprises fours sides joined by pairs at four corners. Alternatively, the spacer grid 8 may exhibit another shape. It may namely exhibit a polygonal shape, for instance a hexagonal contour with six sides joined by pairs at six corners. The spacer grid 8 comprises a peripheral band 11 delimiting the peripheral contour of the spacer grid 8. The peripheral band 11 is composed of elongated peripheral strips 12 each defining one respective side of the peripheral band 11. The spacer grid 8 comprises interlaced intermediate strips 14 extending between two opposed peripheral strips 12 and defining a lattice of cells 16, 16A each for generally receiving one respective fuel rod 4 and at least one opening 18 for receiving the water channel 6. The intermediate strips 14 comprise a first set of parallel strips extending in a first direction and a second set of parallel strips extending in a second direction different from the first direction and intersecting the strips of the first set. Peripheral cells 16, 16A are delimited outwardly by the peripheral strips 12. The spacer grid 8 comprises corner cells 16A located at the corners of the spacer grid 8 and each delimited by the end portions 24 of two adjacent peripheral strips 12. The fuel channel 10 exhibits a transverse section corresponding to peripheral contour of the spacer grid 8. The fuel channel 10 comprises inner walls 20. The spacer grid 8 is received within the fuel channel 10 with a transverse spacing between each side of the peripheral band 11 and a facing inner wall 20 of the fuel channel 10. The spacer grid 8 comprises positioning means for maintaining spacing between the peripheral band 11 and the inner walls 20 of the fuel channel 10. The positioning means comprise elastically deformable springs 22 provided on the peripheral band 11 for biasing the peripheral band 11 away from inner walls 20 of the fuel channel 10. Each spring 22 protrudes outwardly from the outer face 40 of the peripheral band 11. Each peripheral strip 12 is provided with one spring 22 on each longitudinal end portion 24 of the peripheral strip 12. As illustrated on FIG. 3, two springs 22 are provided adjacent to a corner of the peripheral contour of the spacer grid 8, one on each of the two adjacent peripheral strips 12 defining the corner. As illustrated on FIGS. 3 and 4, each spring 22 is stamped in the corresponding peripheral strip 12. More specifically, each spring 22 comprises an elastically flexible cantilevered tab 26 stamped in the peripheral strip 12. The tab 26 is delimited in the peripheral strip 12 by an elongated curved slot 28. The tab 26 is delimited by the slot 28 and an imaginary line joining the opposed ends 30 of the slot 28. As illustrated on FIGS. 3 and 4, the imaginary line extends substantially transversally to the longitudinal edges 32 of the peripheral strip 12 of the peripheral band 11. Each spring 22 extends in cantilever fashion away from the adjacent extremity 34 of the corresponding peripheral strip 12 and thus away from the edge of the adjacent corner. Each spring 22 is provided in the peripheral band 11, between the longitudinal edges 32 of the peripheral band 11. Optionally or alternatively, at least one spring 22 or each spring 22 extends in cantilever fashion towards the adjacent extremity 34 of the corresponding peripheral strip 12 and thus towards the edge of the adjacent corner. Optionally or alternatively, the imaginary line of at least one spring 22 or the imaginary line of each spring 22 extends substantially parallel to the two longitudinal edges 32 of the peripheral strip 12, the at least one spring 22 or each spring 22 extends in cantilever fashion towards one longitudinal edge 32 of the peripheral strip 12. The slot 28 is curved such that it exhibits a generally U-shape with two diverging branches (or V-shape with a rounded tip). The tab 26 converges from its base towards its free tip. In a free state of the spring 22, the tab 26 protrudes from the outer face 40 of the peripheral strip 12 oriented outwardly with respect to the spacer grid 8. The spring 22 comprises a rigid contact projection 36 provided at the free tip of the tab 26. The contact projection 36 protrudes outwardly from the tab 26 to contact the facing inner wall 20 of the fuel channel 10. The contact projection 36 is provided for instance as a dimple stamped in the tab 26. Each peripheral strip 12 comprises at least one rigid stop or motion limiter 38 formed in the peripheral strip 12 for limiting motion of the peripheral strip 12 towards the facing inner wall 20 of the fuel channel 10 and a subsequent overstress of the associated spring 22. Each motion limiter 38 is provided for instance as a rigid dimple stamped in the peripheral strip 12 and protruding outwardly on the outer face 40 of the peripheral strip 12. As illustrated on FIGS. 3 and 4, two motion limiters 38 are provided on two opposite sides of the spring 22. More specifically, one motion limiter 38 is provided above the spring 22 and the other motion limiter 38 is below the spring 22 such that the motions limiters 38 are vertically aligned with spring 22. Alternatively, the two motion limiters 38 are provided one in front of the spring 22 adjacent the free end of the spring 22 and the other behind the spring 22 adjacent the hinged end of the spring 22. Alternatively, only one motion limiter 38 is provided above the spring 22, below the spring 22, in front of the spring 22 adjacent the free end of the spring 22 or behind the spring 22 adjacent the hinged end of the spring 22. Alternatively more than two motion limiters may be provided. Each motion limiter 38 exhibits a protruding height inferior to the protruding height of the associated spring 22 in the free state of the spring 22. The peripheral band 11 comprising elastically deformable springs 22 allows elastic positioning of the spacer grid 8 in the fuel channel 10 with an appropriate adjustable force to ensure appropriate spacing and good performances. Motion limiters 38 avoid overstress of the springs 22 and provide minimal spacing. As illustrated on FIGS. 3 and 4, the peripheral strip 12 comprises two identical springs 22, one at each end portion 24 of the peripheral strip 12. Alternatively, one peripheral strip 12 may comprise two different springs 22 exhibiting different shapes, heights and/or spring rates, e.g. for obtaining a specific positioning of the spacer grid 8 relative to the fuel channel 10, namely an off-centered positioning. Similarly, the peripheral strips 12 of a spacer grid 8 may comprise identical springs 22 or alternatively different springs 22 exhibiting shapes, heights and/or spring rates, e.g. for obtaining a specific positioning of the spacer grid 8 relative to the fuel channel 10, namely an off-centered positioning. The spring 22 integrally formed in one-piece in a peripheral strip 12 results in a simplified design of the spacer grid 8 and a reduced number of fabrication steps and reduced flow resistance, namely as compared to springs assembled to the peripheral band 11. In the embodiments of FIGS. 2-4, springs 22 are provided at the two end portions 24 of each peripheral strip 12 whereby two springs 22 are provided close to each corner of the spacer grid 8 on the two corresponding sides. Alternatively, a peripheral strip 12 may be provided with one spring 22 on one end portion 24 of the peripheral strip 12. The spacer grid 8 might thus be provided with springs 22 adjacent only to every other corners of the spacer grid 8, e.g. springs 22 adjacent to two diagonally opposed corners. Alternatively, at least one of the peripheral strips 12 of a spacer grid 8 may comprise more than two springs 22 for instance spaced along the peripheral band 11 transversally to the assembly axis L. In the embodiment of FIGS. 2-4, the peripheral band 11 is composed of several initially separate peripheral strips 12 assembled in pairs at their longitudinal end, e.g. by welding. The peripheral band 11 delimits a continuous closed contour. Each pair of adjacent mutually assembled end portions 24 delimits together with two intersecting intermediate strips 14 a corner cell 16A of closed contour adapted for transversely maintaining a fuel rod 4 received in the corner cell 16A. Each corner cell 16A is located at a corner of the spacer grid 8. In an alternative embodiment, the peripheral strips 12 are made in one-piece and are portions of a same single piece of metal bent and assembled at its longitudinal ends to define the peripheral band 11. In the alternative embodiment of FIG. 5 illustrating a corner of a spacer grid 8 in perspective view, the peripheral band 11 is cut at a corner of the spacer grid 8 in such a manner that the two adjacent end portions 24 of adjacent peripheral strips 12 end at a distance from each other and are separated by an aperture 42. The cut peripheral band 11 is discontinuous. This alternative embodiment may be implemented with the spring 22 as described above. Alternatively, as illustrated on FIG. 5, each end portion 24 is free and forms a cantilevered positioning spring 22 protruding outwardly relative to the spacer grid 8 for contacting a facing wall adjacent the periphery of the spacer grid 8, namely a facing inner wall 20 of the fuel channel 10. The end portions 24 thus delimit together with two intersecting intermediate strips 14 a corner cell 16A laterally opened. Each end portion 24 defines an elastically flexible cantilevered tab 26 extending in cantilever from a connection of the peripheral strip 12 with an intermediate strip 14. Each end portion 24 is configured to contact the facing inner wall 20 of the fuel channel 10 while being elastically deformable for elastically positioning the spacer grid 8. The end portions 24 are independently elastically flexible. Separate end portions 24 of the peripheral strip 12 allow elastic positioning of the spacer grid 8 while allowing to obtain the spacer grid 8 with a reduced number of parts and a reduced number of operation, namely without welding of the peripheral strip 12 at the corner of the spacer grid 8. Optionally, each end portion 24 is provided with a rigid contact projection 44 protruding outwardly from the tab 26 to contact the facing inner wall 20. The contact projection 44 is provided e.g. as a rigid dimple stamped in the end portion 24. By varying the height and length of the dimple, the positioning performances of the spacer grid 8 may be optimized. Optionally, each end portion 24 is provided with at least one slot 46 to adjust the spring force of the tab 26. Optionally, each peripheral strip 12 is provided with at least one motion limiter 38 located adjacent to the free end portion 24 for avoiding overstress. The motion limiter 38 is preferably formed in a fixed portion of the peripheral strip 12 out of the cantilevered end portion 24. As illustrated on FIG. 5, the motion limiter 38 is formed in a fixed portion of the peripheral strip 12 opposite the end portion 24 relative to a connection with an intermediate strip 14. In one embodiment, the peripheral band 11 is cut at each corner and each peripheral strip 12 has its two end portions 24 configured as springs 22. Springs 22 are provided at each corner of the spacer grid 8. In an alternative embodiment, peripheral strip end portions 24 configured as springs 22 are provided only at a limited number of the corners of the spacer grid 8 inferior to the total number of corners of the spacer grid 8, e.g. at two diagonally opposed corners of the spacer grid 8. In such an embodiment, one peripheral strip 12 may have one end portion 24 configured as a spring 22 and the other opposite end portion 24 assembled to that of another peripheral strip 12 and optionally provided with spring 22, projection 36 and motion limiter 38 according to the first embodiment of the invention. The bundle of fuel rods 4 may comprise full-length fuel rods 4 and part-length fuel rods 4 of shorter length than the full-length fuel rods. A spacer grid 8 provided with a peripheral band 11 cut at a corner is especially adapted when the bundle of fuel rods 4 comprises a part-length fuel rod at said corner. As illustrated on FIG. 2, the spacer grid 8 exhibits a square peripheral contour and defines a 11×11 square lattice of cells 16 with the opening 18 replacing a 3×3 array of cells 16. Other arrangements may be contemplated by varying the number of cells 16 in the lattice (e.g. 9×9, 10×10 12×12), the peripheral contour of the spacer grid 8 and corresponding lattice (for instance square shaped, rectangular shaped or hexagonal shaped). Similarly, the number, shape and size of the water channel 6 may vary. Hence, the number of openings 18 for receiving water channel(s) or water rods (one opening 18, two openings 18 or more) and the size and shape of the openings 18 for receiving water channels or water rods (1×1, 1×2, 2×1, 2×2, 2×3, 3×3 . . . ) may vary correspondingly. The invention applies in particular to fuel assemblies comprising a fuel channel, where it is preferable to maintain an adequate spacing between the bundle of fuel rods and the inner walls of the fuel channel to allow adequate flow of coolant/moderator in the fuel channel between and around the fuel rods, i.e. namely to BWR or VVER fuel assemblies.
	summary
	summary
	claims	1. A method for a self-charging battery cell, comprising: providing a Strontium-90 source, the Strontium-90 source having a beta emission; activating a sensor device by the beta emission; generating electric energy by the sensor device from the beta emission, wherein the sensor device converts an intake from the beta emission into electric energy; and the self-charging battery cell is configured to restore a Lithium ion cell to full charge using the generated electric energy from the Strontium-90 source. 2. The method of claim 1, wherein the sensor device is at least one of a semiconductor light sensor and a thermoelectric heat sensor. 3. The method of claim 2, wherein the sensor device is at least one of a photodiode and a photocell. 4. The method of claim 3, wherein the sensor device is configured to convert light into at least one of electric current and voltage. 5. The method of claim 1, wherein the self-charging battery cell is used in a Lithium ion cell. 6. A method for a self-charging battery cell, comprising: providing a Strontium-90 source, the Strontium-90 source having a beta emission; converting the beta emission into light using a scintillation device; activating a sensor device by the light converted by the scintillation device; and converting the light into electric energy by the sensor device; wherein the self-charging battery cell is used in a Lithium ion cell. 7. The method of claim 6, wherein the scintillation device is at least one of a scintillation crystal, an organic scintillation crystal, and an inorganic scintillation crystal. 8. The method of claim 6, wherein the scintillation device converts electrons from the beta emission into at least one flash of light. 9. The method of claim 8, wherein the sensor device is at least one of a photodiode and a photocell. 10. The method of claim 8, wherein the sensor device is configured to convert light into at least one of electric current and voltage. 11. A system for a self-charging battery cell, comprising: at least one Strontium-90 source, the at least one Strontium-90 source having at least one beta emission; at least one scintillation device, the at least one scintillation device being disposed near the at least one Strontium-90 source; at least one sensor device, the at least one sensor device being disposed near the at least one scintillation device; wherein the at least one scintillation device is disposed near enough to the at least one Strontium-90 source so that the at least one scintillation device can intake electrons from the at least one beta emission and convert the at least one beta emission into light. 12. The system of claim 11, wherein the at least one sensor device is disposed near enough to the scintillation device so that the at least one sensor device is activated by the light, the at least one sensor device being configured to convert the light into electric energy. 13. The system of claim 12, wherein the scintillation device is at least one of a scintillation crystal, an organic scintillation crystal, an inorganic scintillation crystal. 14. The system of claim 12, wherein the Strontium-90 source is sandwiched between at least two scintillation devices, and the at least one sensor device is disposed adjacent to each of the at least two scintillation devices. 15. The system of claim 12, wherein the Strontium-90 source is surrounded by the at least one scintillation device, the at least one scintillation device forming an effective cylindrical wall around the Strontium-90 source, and the at least one sensor device being disposed outside the effective cylindrical wall. 16. The system of claim 12, wherein one or more of the battery cell is housed in a compact sealed container. 17. The system of claim 12, wherein the battery cell is used to at least one of recharge existing battery cells and serve as the battery cell to provide electric energy for an electronic device. 18. A method for a battery cell, comprising: providing a Strontium-90 source, the Strontium-90 source having a beta emission; exposing at least one water molecule (H.sub.2O) to the Strontium-90 beta emission, wherein the Strontium-90 beta emission effects a production of hydrogen from the at least one water molecule; further comprising: charging a nickel-hydrogen battery cell with the production of hydrogen.
047864605	claims	1. An installation for handling assemblies forming a core of a fast neutron nuclear reactor, between a primary station situated in a main vessel containing the core and a secondary station situated in an adjoining vessel, said installation comprising: at least one pivotable transfer hood, means for pivoting the hood around a vertical axis, two inclined ramps for connecting the hood to the primary station and the secondary station respectively, at least one pot for transporting an assembly, means for lifting said at least one pot along guiding means inside each of the ramps and the pivotable hood between the primary station and the secondary station, and means for closing the ramps at their top ends when the reactor is operating, comprising two flaps, the hood being attached to a rotary horizontal platform such that the hood and platform rotate as a unit around said vertical axis, said flaps being mounted on the platform in locations such that the flaps can be simultaneously placed above the top ends of the ramps by said means for pivoting the hood when the reactor is operating, said at least one pot comprising two pairs of wheels cooperating with the guiding means. 2. An installation according to claim 1, wherein the transfer hood comprises a thick tube inclined at an angle identical to that of the ramps, so that it can be placed in an extension of each of said ramps when the means for pivoting the hood are operated. 3. An installation according to claim 2, wherein the thick tube is lined externally with a heat insulation cooperating with the tube to bound an annular space for the circulation of a cooling fluid, openings bounded by windows formed at a top and bottom of the heat insulation being controlled by closure members. 4. An installation according to claim 3, wherein heating means are disposed around the thick tube in contact therewith. 5. An installation according to claim 1, wherein the rotary platform also bears a spare flap disposed beneath a demountable plug extending through the platform, a flap-receiving station formed by a recess formed on a fixed base plate disposed below the platform, thereby enabling one of the two flaps to be interchanged with the spare flap. 6. An installation according to claim 5, wherein the spare flap and the hood are disposed in two locations such that they can be placed simultaneously above the top ends of the ramps by the means for pivoting the hood when the reactor is shut down. 7. An installation according to claim 5, wherein a closure member adapted to be attached to an open bottom end of the hood is located in a recess formed in the base plate, the hood being demountably mounted on the rotary platform. 8. An installation according to claim 7, wherein the closure member is located in the recess in the flap-receiving station. 9. An installation according to claim 5, wherein the ramps rest on the base plate via swivel links and can expand freely downwards. 10. An installation according to claim 5, wherein the base plate rests via a swivel joint on a tube connected to a slab closing the main vessel, the tube enclosing the ramp connected to the primary station and the base plate moreover resting via sliding supports on a floor into which the ramp connected to the secondary station opens. 11. An installation according to claim 1, wherein the means for lifting the at least one pot comprise two cables wound at one end on two drums simultaneously actuated by a common motor assembly, the opposite end being attached to the at least one pot, means being provided, to detect any imbalance between the forces exerted on each of the cables. 12. An installation according to claim 1, wherein the guiding means inside each of the ramps and the pivotable hood are rails, the ends of the rails of the hood and of the rails of the ramps being separated by a limited clearance when such rails are aligned. 13. An installation according to claim 1, wherein each of the flaps is mounted on the rotary platform via a control mechanism enabling the flap to be moved between a top position in which the flap is retracted into a recess in the rotary platform and a bottom position in which the flap closes the end of one of the ramps, the control mechanism also comprising means for gripping the flap.
	abstract	A pressurized water reactor (PWR) includes: a pressure vessel divided into an upper plenum containing primary coolant, a lower plenum containing primary coolant, and a steam generator plenum interposed between the upper plenum and the lower plenum and containing secondary coolant; a nuclear reactor core comprising fissile material disposed in the lower plenum; one or more risers arranged to convey primary coolant upward from the nuclear reactor core to the upper plenum; and a plurality of tubes passing through the steam generator plenum and arranged to convey primary coolant downward from the upper plenum to the lower plenum. A steam separator is operatively connected with the steam generator plenum to separate secondary coolant in the steam phase from secondary coolant in the water phase.
055531083	summary	TECHNICAL FIELD This invention relates generally to fuel bundle constructions for boiling water nuclear reactors, and specifically to water rod attachment techniques within such bundles. BACKGROUND PRIOR ART FIGS. 1, 2A and 2B of this application illustrate a conventional fuel rod bundle assembly B for a boiling water reactor (BWR) including an upper tie plate U, a lower tie plate L and a matrix of vertically upstanding fuel rods R extending between the two tie plates. The tie plates support the fuel rods R and also permit the inflow of water at the lower tie plate L and the out flow of water and generated steam at the upper tie plate U. An elongated channel C of substantially square cross sectional shape encloses the fuel rods R and confines the fluid flow within the fuel bundle B to a path between the respective tie plates L and U. Similar constructions are disclosed in commonly owned U.S. Pat. Nos. 5,174,949 and 4,675,154. To aid in equalizing neutron moderation, the fuel bundle B is fitted with a large water tube or rod W for conveying relatively cool water upward through the central region of the fuel assembly. Typically, the water rod W occupies four lattice positions in the fuel rod bundle, displacing four fuel rods. Transition pieces 14, 16 at the top and bottom of the rod connect the large diameter central part of the water rod to smaller diameter tubes 20, 22, respectively. At the upper end of the rod (see especially FIG. 2B), the small diameter tube 20 terminates in a circular end plug 12 which fits into the upper tie plate U. A spring 23 fits over the end plug 12 and bears against the lower surface 24 of the upper tie plate U. The spring 23 biases the water rod W downwardly against the lower tie plate L. Referring to FIG. 2A, the smaller diameter tube 22 at the lower end of the water rod W has a tapered flange 25 received in a square end plug 30 which, in turn, fits into a square hole 32 in the lower tie plate L. The square end plug 30 and square hole 32 prevent rotation of the water rod W. Such rotation must be prevented to insure capture of the fuel bundle spacers (one of several shown at S) to the water rod W. The function of the small diameter tube 22 is to provide flexibility to accommodate seismic movement of the lower tie plate L relative to the large water rod W in the fuel bundle B. The lower tube 22 has-relatively large diameter holes 36 in its lower portion. These holes 36 act as inlets for water from the single phase region at the bottom of the fuel bundle B. These inlet holes must be near the bottom of fuel bundle B to insure that only water and no steam enters water rod W. The upper end of tube 22 communicates with a central hole 40 in the lower transition piece 16, through which water enters the main large diameter part of water rod W. This hole 40 acts as an orifice and is sized to provide the correct water flow through the water rod W. Water exits the large diameter portion of the water rod through holes 42 at the upper end of the large diameter portion of rod W, as illustrated in FIG. 2B. In addition, the spring loaded rod 20 at the upper portion of water rod W is provided with holes 44 to provide required local circulation. As already noted, circular water rods have been used to capture the fuel rod spacers S located along the length of the bundle B, to prevent axial movement of the spacers S with respect to the fuel rods R and the water rod W, and also to assist in the fuel bundle assembly process. Tabs (not shown) are welded on the water rod W at axial locations just above and below the location of each spacer S. The water rod W is inserted through the spacers S with an angular orientation such that the tabs pass through the spacers S. The water rod W is then rotated to a locked orientation. As already noted above, the square lower end plug 32 is inserted into the square lower tie plate hole 34. The water rod W thus remains fixed against rotation in that angular orientation while the tabs prevent any axial movement of the spacers S. DISCLOSURE OF THE INVENTION The invention here provides a simple yet highly reliable connection between one or more (two in the exemplary embodiment) water rods and the lower tie plate. In the preferred arrangement, the lower end plug of the water rod is threaded, but is also formed with a diametrical slot extending across and through the threaded end. At the same time, the lower tie plate boss is formed with a threaded hole for receiving the end plug. In accordance with this invention, the boss is formed with a pair of aligned slots on diametrically opposed sides of the hole. When the slot in the end plug is aligned with the slots in the boss, a key may be inserted through the three aligned slots to lock the water rod in the correct angular position. The key may then be fixed to the lower tie plate boss by a small weld to ensure that it does not come loose. In its broader aspects, therefore, the present invention relates to a fuel bundle assembly for a nuclear reactor wherein a plurality of fuel rods and at least one water rod extend between an upper tie plate and a lower tie plate, the improvement comprising first means for removably securing the water rod to the lower tie plate; and second means for cooperating with the first means and for locking the water rod against rotation relative to the lower tie plate. In another aspect, the invention relates to a fuel bundle assembly for a nuclear reactor wherein a plurality of fuel rods and at least one water rod extend between an upper tie plate and a lower tie plate, the improvement comprising a fixed connection between said water rod and the lower tie plate, the fixed connection including a threaded lower end plug of the water rod and a threaded hole in a boss formed in the lower tie plate adapted to receive the threaded lower end plug, the threaded lower end plug formed with a diametrical slot therein and the boss formed with a pair of slots extending from opposite sides of the hole such that the diametrical slot and the pair of slots are alignable when the threaded lower end plug is threaded into the boss; and a key insertable within the aligned slots to thereby fix the water rod against rotational movement. It should be noted that the above described water rod attachment technique can be applied to one or both of the water rods in the bundle. The above described arrangement permits the elimination of the attachment components described above at the upper end of the water rod, i.e., the upper end plug 12, the upper extension tube 20, transition piece 14 and spring 23. Other objects and advantages of the invention will become apparent from the detailed description which follows.
063320126	description	DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS The strap 12 shown in part in FIG. 1 has a structure very similar to that described in the abovementioned French patent. It has notches 16 designed to co-operate with straps constituting a second set. Each zone situated between two notches and designed to separate two cells for rods carries springs 22 and bearing bosses 28. Each spring is made up of two resilient strips 24 cut out from the strap and interconnected in the middle by a transverse bridge 26. In the flow direction, each spring 22 is positioned between two bosses 28, likewise in the form of bridges. The bridges 26 and the bosses 28 may be of the same shape. The edge of the plate that is to be situated downstream in the flow direction, once the plate is in provided in a grid, may carry mixing fins 29. To increase the transparency of a grid built up from crossed straps, concave-shaped chamfers are provided at least in the vicinity of the upstream edge of the strap. In general, the flow in a pressurized water reactor is upwards and the upstream edge is constituted by the bottom edge. FIGS. 1 and 2 show chamfers 31 that are relatively easy to make and that do not weaken the edge excessively. The chamfering of each face extends over a distance b that is slightly less than the thickness a of the strap. For a grid made up of straps of the zirconium alloy known as Zircaloy 4, and having a thickness a=0.425 mm, the length b may be 0.35 mm. The upstream edge must not be too thin, as otherwise the edges will be weakened and may become indented in the event of an impact. However, the chamfers must be large enough to increase the transparency of the grid to a significant extent. In practice, the thickness along the edge will be selected to be close to half the common thickness a. Although various concave profiles can be used to make the chamfer, it is advantageous to use a shape that is in the form of a circular sector having its center situated beyond the upstream face of the grid constituted by the straps of the invention. In particular, it is possible to use a cylindrical shape of radius R and center C situated at a distance c beneath the upstream edge of the strap, where c is of the same order as b, and at a distance d from the axis of the strap that is equal to several times a. In practice, good results have been obtained with a strap of thickness a=0.425 mm, when c=0.3 mm, and d=2.1 mm. The chamfers may be provided either on either side of the crossings with orthogonal straps, or else along the full length of a strap. The straps may be attached together by welding either on the downstream face, or using beads along the dihedral angles, or indeed in windows such as 33. In the variant shown in FIG. 3, which is not to scale for reasons of clarity, the chamfer is of varying height. It is defined by a line 30 starting from the upstream edge close to each slot 16 and reaching a maximum distance from said edge in the middle of the face of a cell. Under such circumstances, the thickness of the edge is at a minimum in the middle of the wall of a cell and reaches the common thickness at the points where the strap crosses other straps. In the embodiment shown in FIG. 4, again not to scale, each chamfer for a strap 12 or 14 is again defined by a line 30 extending from the edge of the strap at its cross-points with two other straps. In addition, the upstream edge of the strap is neither of constant thickness nor rectilinear. This upstream edge has a curved shape serving to recenter the streams of coolant liquid towards the rods, such as the rod 32 shown diagrammatically in FIG. 2. To further improve the transparency of a grid as shown in FIG. 1, the bridges 26 and the bosses 28 may also be chamfered. However, under such circumstances, it is possible to use chamfers that are straight and plane, given the small sizes thereof. By way of example, FIG. 5 shows chamfers that can be formed on the upstream and downstream edges of a bridge, prior to the sheet being deformed, so as to constitute the bosses and the springs. An angle .alpha. of the chamfers equal to about 20.degree. has given good results. The thickness e of the edges can be that of the upstream edge of the strap, i.e., no more than 0.5 mm for a=0.425 mm, for example.
046481060	summary	CROSS-REFERENCES TO RELATED APPLICATIONS This invention relates to and may be utilized in the lithographic system disclosed in U.S. application Ser. No. 487,943 filed Apr. 25, 1983 entitled "Lithographic System" by W. Thomas Novak, Inventor; and U.S. application Ser. No. 475,427 filed Mar. 15, 1983 entitled "Mask Alignment Apparatus" by Anwar Husain, Inventor. The disclosure of such applications are herein incorporated by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to a lithographic alignment system particularly one usable in a system employing X-ray or other beams for printing replicas of patterns or masks on photo sensitive materials contained on semiconductor substrates such as silicon wafers, wherein the inert gas between the X-ray source and mask and the wafer fabrication process gas between the mask and wafer are controlled in terms of purity attenuation, oxygen content and leakage losses, and in pressurization levels affecting the mask-to-wafer gap. 2. Description of the Prior Art U.S. Pat. No. 4,185,202 discloses as prior art an X-ray lithography system involving an X-ray source, an X-ray transmission chamber 14 and an imaging or exposing chamber 18 into which a prealigned mask-wafer fixture is moved into position under the source at the bottom of the exposing chamber for each exposure. The transmission chamber is maintained in a vacuum at a pressure less than about 10.sup.-6 torr while helium is present in the imaging or exposure chamber or a 10.sup.-2 torr vacuum provided which limits the throughout capabilities of the system. The improvement in the '202 patent is directed to having a movable (expandible) exposure chamber 40 with a side wall 46 which is lowered to engage the mask-wafer fixture. Helium is flowed into chamber 40 for each exposure at a rate of 10 liters/minute through passageway 42. A separate atmosphere of inert gas e.g. nitrogen at a rate of 2.9 liter/minute at a pressure of 5-50 psi is provided into the fixture and the zone between the mask underside and the wafer. Flushing of the zone is initially started while the fixture is still being loaded remote from the exposure chamber. The '202 patent also mentions that it may be advantageous to maintain the pressure in the exposure chamber greater than in the mask-to-wafer zone to prevent gaseous constituents in the latter being introduced to the former and contemplates addition of a small amount of inhibiting oxygen in the mask-to-wafer zone. In the prior art the respective gases are both allowed to escape to the atmosphere in a relatively uncontrolled manner, typically the helium leaking profusely near the mask edge and exiting from the junction of the chamber and a bottom frame, and the process gas being injected in the vicinity of the wafer edge, in an attempt to maintain the proper gas environment and allowed to exit between the chuck and bottom frame. SUMMARY In an X-ray alignment apparatus, proper control of gas environments is essential for overall performance in two critical areas. The first relates to the helium gas between the X-ray exposure source and the X-ray mask, and the second relates to wafer fabrication process gases between the mask and the wafer which is being exposed. The problems arise due to several competing factors. First, the purity of the helium in the exposure chamber must be kept high in order to reduce the X-ray exposure time to a minimum. A second factor is the need, in certain cases, to have a special wafer fabrication process gas in between the mask and the wafer. As an example, it may be desirable to have a gas mixture of about 0.3% oxygen in nitrogen present above the substrate resist for an optimum exposure. The oxygen in the gas reacts with the resist during exposure to obtain certain desirable printing characteristics. A third factor is that the helium gas required is somewhat costly, and steps should be taken to minimize its use. This in turn improves the economic viability of the X-ray lithography system. A fourth factor is that due to the membrane nature of the X-ray mask, any differential pressure across the mask must be kept to a minimum. A pressure differential will cause the mask to deflect upward or downward, and therefore cause the mask-to-wafer gap to vary. This gap would also not be uniform across the wafer since the membrane would deflect more in its middle than at its supported peripheral edges and would introduce additional printing distortion. The allowable pressure difference is so small as to be not economically measurable by available sensors. However, the first two factors which have been mentioned tend to cause there to be two different gases on either side of the mask membrane. The present invention is an improved X-ray lithographic system and substrate or wafer fabrication method in which the gases in the exposure chamber and in the abutting mask-to-wafer zone are controlled more exactingly and their usage significantly reduced. These advantages are realized by providing an inert gas vent tube adjacent to the bottom of the exposure chamber and of a design to prevent back diffusion from the surrounding exterior ambient and prevent mask membrane deflection. Further, the helium purity within the chamber can be continually monitored by providing an oxygen detector in the vent line. The present invention also provides an improved means for venting, sealing and controlling the pressure in the mask-to-wafer zone, including a gas flange interposed between a wafer-holding chuck and the mask holder, or in an alternative embodiment providing a vent tube for allowing a controlled purge of gas from the mask-to-wafer zone. This prevents contamination of that zone by ingress of ambient air without unduly pressurizing the underside of the mask membrane being acted upon on its top side by the helium or other inert gas in the X-ray exposure chamber. Providing an essential zero pressure differential across the mask membrane obviates any change in the gap distance between the mask membrane and the wafer.
046684689	summary	This invention was made under contract with or supported by the Electric Power Research Institute, Inc. BACKGROUND OF THE INVENTION 1. Field of the Invention: The invention relates in general to a fuel pellet for a fuel rod of a fuel assembly of a nuclear reactor core and in particular to a fuel pellet having fissile, fertile, and burnable poison material disposed at predetermined radial locations within the fuel pellet. 2. Description of the Prior Art: To generate a predetermined amount of energy, a fuel assembly is loaded with fuel rods which include pellets enriched in fissile material (for instance, UO.sub.2 pellets enriched in U.sub.235). The nuclear reactivity (known in the art as K which is defined as the number of fissions in one generation divided by the number of fissions in the preceeding generation) of such an assembly is highest at the beginning of life and lowest at the end. To produce a certain fission rate at the end of life, excess enriched material is provided at the beginning of life. The reactivity of the assembly must be kept within tolerable limits at all times. The most limiting condition is early in the life of the core, since the reactor control system may not have sufficient nuclear worth to maintain the core subcritical by a certain margin in the cold condition due to the high reactivity of the fuel. The reactivity of the fuel assembly can be controlled by fuel rods having fuel pellets containing a burnable poison dispersed therein. The burnable poison is added in sufficient quantity to suppress the reactivity of the fuel to a level consistent with the capabilities of the reactor control system so that the reactor safety design criteria can be met. The burnable poison fuel rods are located in the interior of the fuel assembly so that the burnable poison does not become prematurely depleted, and so that the nuclear interaction between the control rods in the reactor and the burnable poison fuel rods is minimized. The fuel pellets containing the burnable poison are a homogeneous mixture of fissile and fertile nuclear materials and burnable poison materials. The powders containing these materials are blended and mixed in a manner to promote maximum dispersal of the materials into a homogeneous mixture. The burnable poison material tempers the excess reactivity of the enriched materials by absorbing neutrons throughout the lifetime of the fuel assembly. However, it is only necessary to restrain the excess reactivity of the fuel assembly near the beginning of the fuel cycle. Thereafter the excess burnable poison materials that are necessary to temper the reactivity of the fuel assembly near the beginning of the cycle continue to decrease the reactivity and the power output of the fuel assembly throughout the lifetime of the fuel assembly long after the beneficial control at the beginning of the cycle is necessary. The neutron absorption strength of the burnable poison is proportional to the concentration of the burnable absorber and the surface area of the absorbing material. Under the teachings of current state of the art, the concentration of the burnable neutron absorber at the beginning of life of the fuel assembly is selected so that enough burnable poison atoms are available in the proximity of the absorbing surface to maintain the reactivity of the fuel assembly below a predetermined value at some point in time in the life of the fuel assembly. For example, for boiling water reactors, the most limiting condition from a nuclear safety design point of view occurs after a few months of operation in the first cycle, somewhere towards the middle of the cycle. The rate of burnable poison depletion is controlled by increasing or decreasing the number of fuel rods which include the poison atoms (i.e. increasing or decreasing the absorbing surface area). Accurate and optimized control of reactivity is difficult to achieve. As the number of burnable poison fuel rods is increased while decreasing the absorber concentration per rod (a situtation which favors rapid depletion of the poison and reduced end of cycle reactivity penalties) the power distribution within the assembly early in life becomes more distorted as the power generated in the peak rod increases relative to the average power in the assembly, trending towards unacceptable regions based on thermal hydraulics and nuclear design and safety considerations. Alternatively, as the number of burnable poison fuel rods is decreased (i.e. the burnable poison atoms are concentrated at few locations) the depletion rate of the poison is reduced and the end of cycle residual poison reactivity penalties are increased. These penalties are compensated for by increasing the enrichment of fissile material within the fuel assembly which, accordingly, corresponds to higher costs for the fuel assembly. Therefore it would be desirable to have a means for minimizing the amount of burnable poison material that is necessary to be disposed within the fuel assembly and for controlling the reactivity of the fuel assembly without increasing the number of burnable poison fuel rods. It would further be desirable to have a means to control the reactivity of the nuclear fuel assembly without the use of burnable poison material. SUMMARY OF THE INVENTION Briefly, the present invention is a novel fuel pellet for a fuel rod of a nuclear reactor fuel assembly having a body containing a mixture of nuclear fuel material and a burnable poison material and a means for controlling the radial disposition of the burnable poison material, the fissile material, and the fertile material within the body to minimize the amount of burnable poison material necessary to control the reactivity of the fuel pellet to provide for control of the K value of the fuel assembly and to optimize the amounts of fissile and fertile material necessary for a given power output. The burnable poison material may be disposed at a predetermined radial location by means of the body of the nuclear fuel pellet having both an inner part and an outer part integral with and surrounding the inner part. The inner or the outer part, or both, may have the homogeneous mixture of the burnable poison material with the nuclear fuel material. The present invention teaches 3 pellet designs: (A) a fuel pellet in which all of the fissile material and all of the burnable poison material are homogeneously mixed with fertile material and segregated to the outer part of the pellet and surrounding an inner part in which only natural or depleted nuclear material is present; (B) a fuel pellet in which both the inner and the outer parts contain a mixture of fissile, fertile, and burnable poison material but the concentration of each in either part is different; (C) a fuel pellet in which only natural or depleted nuclear material is included in the outer part, and enriched nuclear material comprises the inner part. The fuel pellets A, B and C constructed according to the teachings of the invention may be disposed within a tubular fuel rod cladding to provide a fuel rod that will limit the reactivity of a fuel assembly at the beginning of a cycle. The fuel assembly may be designed with combinations of fuel rods and the individual fuel rods may contain combinations of fuel pellets. The fuel rod may be located within the fuel assembly both in the interior and at the periphery of the fuel assembly as will be explained further in the detailed description of the preferred embodiments.
062495666	summary	BACKGROUND OF THE INVENTION This invention relates to an apparatus for X-ray analysis which uses a composite monochromator having combined two elliptic monochromators, the composite monochromator being arranged between an X-ray source and a sample. In the field of X-ray analysis, there has always been required to make the X-ray intensity as high as possible. A stationary-anode X-ray tube (e.g., 0.4 mm.times.12 mm in focal spot size and 2.2 kW in maximum power) has a limit for increasing the X-ray intensity. To overcome this limitation, a rotating-anode X-ray tube which provides a higher X-ray intensity has been developed and used. There has also been used synchrotron radiation which provides a much higher X-ray intensity. The X-ray generator having such a higher X-ray intensity, however, is big and complicated in handling, and further spends much energy. Under the circumstances, there is more and more of a need to develop an apparatus for X-ray analysis which can increase the X-ray intensity on a sample even though it can be handled easily in laboratories. Assuming that a sample is set at a distance of several hundred millimeters apart from an X-ray source and an X-ray beam is incident on the sample directly from the X-ray source, the sample receives only a very small percentage of the X-rays which are emitted in all directions from the focal spot on the target of the X-ray source. Accordingly, it is known that optical elements such as mirrors or monochromators are used to focus X-rays on the sample. Persons in the art have sought for an improved focusing efficiency of such an X-ray optical system to save energy further. Elliptic or parabolic focusing elements with a synthetic multilayered thin film have recently been developed and given attention by persons in the field of X-ray analysis, the elements having high focusing efficiencies and high reflectivity for X-rays of a predetermined wavelength of interest. The focusing elements of this type are disclosed, for example, in U.S. Pat. Nos. 5,799,056; 5,757,882; 5,646,976; and 4,525,853; and M. Schuster and H. Gobel, "Parallel-Beam Coupling into Channel-Cut Monochromators Using Curved Graded Multilayers", J. Phys. D: Appl. Phys. 28(1995)A270-A275, Printed in the UK; G. Gutman and B. Verman, "Comment, Calculation of Improvement to HRXRD System Through-Put Using Curved Graded Multilayers", J. Phys. D: Appl. Phys. 29(1996)1675-1676, Printed in the UK; and M. Schuster and H. Gobel, "Reply to Comment, Calculation of Improvement to HRXRD System Through-Put Using Curved Graded Multilayers", J. Phys. D: Appl. Phys. 29(1996)1677-1679, Printed in the UK. There are further disclosed structures of the synthetic multilayered thin film for X-ray reflection and methods for producing them, for example, in Japanese Patent Post-Exam Publication No. 94/46240 and U.S. Patent No. 4,693,933. The synthetic multilayered thin film acts as a focusing monochromator for X-rays. It is certain that a combination of an ordinary X-ray source and the above focusing-type synthetic multilayered thin film may greatly increase the X-ray intensity on a sample. There will now be described with reference to FIGS. 5 to 12 the shape, structure and function of the prior-art elliptic monochromator having the synthetic multilayered thin film. First, the meaning of the terms "elliptic monochromator", "elliptic-arc surface" and "focal axis" will be described. Referring to FIG. 5, a three-dimensional rectangular coordinate axis XYZ is set in space and an ellipse 10 is drawn in an XY-plane. Imagining a curve 12 which is a portion of the ellipse 10, the curve 12 is referred to hereinafter as "elliptic-arc". The elliptic-arc 12 is translated in the Z-direction (i.e., the direction perpendicular to the plane including the elliptic-arc 12) to make a trace which becomes a curved surface 14. The curved surface 14 is referred to hereinafter as "elliptic-arc surface". The two foci F.sub.1 and F.sub.2 of the elliptic-arc surface 12 are translated in the Z-direction to make two traces 20 and 22 each of which is referred to hereinafter as "focal axis". The focal axes 20 and 22 of the elliptic-arc surface 14 become parallel to the Z-axis. A normal line drawn at any point on the elliptic-arc surface 14 becomes always parallel to the XY-plane. Under the above positional relationship, the elliptic-arc surface 14 can be represented by "elliptic-arc surface with focal axes parallel to the Z-axis". It should be noted that the monochromator whose reflecting surface consists of an elliptic-arc surface is referred to simply as "elliptic monochromator". Next, the function of the elliptic monochromator will be described. Referring to FIG. 6, imagine an elliptic monochromator 24 with focal axes parallel to the X-axis. The drawing sheet of FIG. 6 is parallel to the YZ-plane. The reflecting surface 26 of the elliptic monochromator 24 appears as an elliptic-arc on the drawing sheet of FIG. 6. In view of geometrical optics, a light ray emitted from a light source, which is positioned at one focal point F.sub.1 of the elliptic-arc, is reflected at the reflecting surface 26 and reach the other focal point F.sub.2. In view of X-ray optics, an X-ray emitted from an X-ray source, which is positioned at one focal point F.sub.1, may be reflected at the reflecting surface 26 only when an X-ray incidence angle .theta. on the reflecting surface 26, an X-ray wavelength .lambda. and the lattice spacing d of crystal of the reflecting surface 26 satisfy the Bragg equation for diffraction. The reflected X-ray will reach the other focal point F.sub.2. It should be noted that the lattice surfaces of crystal contributing to the diffraction are parallel to the reflecting surface 26. Incidentally, the X-ray incidence angle .theta. on the reflecting surface 26 depends upon the position, on which an X-ray is incident, of the reflecting surface 26 of the elliptic monochromator 24. Therefore, to satisfy the Bragg equation at any point of the reflecting surface 26, the lattice spacing must be graded along the elliptic-arc (i.e., must vary with the incidence angle .theta.). The elliptic monochromator for X-rays has accordingly a synthetic multilayered thin film in which the d-spacing of the multilayers varies continuously. The d-spacing varying continuously is referred to hereinafter as graded d-spacing. FIG. 7 shows the functional principle of the elliptic monochromator having graded d-spacing. X-rays emitted from the X-ray source 32 are incident on a point A, having d-spacing d.sub.1, of the reflecting surface 26 of the elliptic monochromator 24 with an incidence angle .theta..sub.1 and on a point B having d-spacing d.sub.2 with an incidence angle .theta..sub.2. The Bragg equation at the point A is EQU 2d.sub.1 sin.theta..sub.1 =.lambda. (1) where .lambda. is the wavelength of the X-rays. The Bragg equation at the point B is EQU 2d.sub.2 sin.theta..sub.2 =.lambda.. (2) If the positional relationship between the X-ray source 32 and the elliptic monochromator 24 is predetermined, the incidence angle .theta. could be calculated at any point of the reflecting surface 26 of the elliptic monochromator 24, and accordingly the d-spacing for every incidence angle .theta. could also be calculated so as to satisfy the Bragg equation. With the use of such an elliptic monochromator having the graded d-spacing, X-rays of a particular wavelength of interest always satisfy the Bragg equation even if the X-rays are incident on any point of the reflecting surface, so that the reflected X-rays of the particular wavelength can be focused at the other focal point F.sub.2. The elliptic monochromator having such a synthetic multilayered thin film per se is known as mentioned above. Referring to FIG. 6, X-rays, emitted from the focal point F.sub.1 and traveling in the direction within a divergence angle .alpha., are reflected by the reflecting surface 26 of the elliptic monochromator 26 and focused on the other focal point F.sub.2 with a convergence angle .beta.. With such a focusing effect, X-rays with the predetermined divergence angle can be utilized effectively, so that the X-ray intensity on the focal point F.sub.2 may be greatly increased as compared with the case of no elliptic monochromator. At the same time, X-rays may be purified into the specific monochromatic rays with the function of the elliptic monochromator 24. While we have considered, with reference to FIG. 6, the focusing of the X-rays which diverge in the XY-plane, the focusing of the X-rays which diverge in the ZX-plane can be realized when we use an "elliptic monochromator with focal axes parallel to the Y-axis". Accordingly, if both the "elliptic monochromator with focal axes parallel to the X-axis" and the "elliptic monochromator with focal axes parallel to the Y-axis" are arranged between the X-ray source and the sample, the focusing for both the divergence in the YZ-plane and the divergence in the ZX-plane can be realized. Under such an arrangement, the X-ray source must be positioned on one focal point of the "elliptic monochromator with focal axes parallel to the X-axis" and at the same time on one focal point of the "elliptic monochromator with focal axes parallel to the Y-axis" too. One arrangement of the elliptic monochromator system which can focus X-rays in both the YZ-plane and the ZX-plane may be a sequential arrangement as shown in FIG. 8A. This arrangement is disclosed in by V. E. Cosslett and W. C. Nixon, "X-ray Microscopy", Cambridge at the University Press, 1960, pp.105-109. Referring to FIG. 8A, X-rays emitted from an X-ray source 32 are reflected first at the first elliptic monochromator 34 (the elliptic monochromator with focal axes parallel to the X-axis) so that the divergence in the YZ-plane is focused. The X-rays are reflected next at the second elliptic monochromator 36 (the elliptic monochromator with focal axes parallel to the Y-axis) so that the divergence in the ZX-plane is focused. Another arrangement is a side-by-side arrangement as shown in FIG. 8B and this arrangement is disclosed in S. Flugge, "Encyclopedia of Physics", Volume XXX, X-rays, Springer-Verlag, Berlin.cndot.Gottingen.cndot.Heidelberg, 1957, pp.324-32. The side-by-side elliptic monochromator system has the first elliptic monochromator 38 (the elliptic monochromator with focal axes parallel to the X-axis) and the second elliptic monochromator 40 (the elliptic monochromator with focal axes parallel to the Y-axis), these monochromators being so combined that one side of the first monochromator 38 is in contact with one side of the second monochromator 40. X-rays emitted from an X-ray source 32 are reflected first at either one of the first elliptic monochromator 38 and the second elliptic monochromator 40, and further reflected, soon after the first reflection, at the other monochromator, so that the X-rays are focused on a convergence point 44. X-rays emitted from the X-ray source 32 must first impinge on the region 42 as indicated by hatching for enabling the sequential reflection on the two elliptic monochromators 38 and 40. Thus, the side-by-side composite monochromator utilizes the sequential reflection at the region 42 near the corner between the two monochromators. FIG. 9A is a view taken in the X-direction of FIG. 8B, and FIG. 9B is a view taken in the Y-direction of FIG. 8B. In FIGS. 9A and 9B, X-rays emitted from the X-ray source 32 are reflected first at a point C on the reflecting surface of the first elliptic monochromator 38 and reflected next at a point D on the reflecting surface of the second elliptic monochromator 40, so that the X-rays are focused on the convergence point 44. In another route as shown in FIGS. 10A and 10B, X-rays emitted from the X-ray source 32 are reflected first at a point E on the reflecting surface of the second elliptic monochromator 40 and reflected next at a point F on the reflecting surface of the first elliptic monochromator 38, so that the X-rays are focused on the convergence point 44. Referring back to FIG. 8B, when seen in the X-direction, the X-ray source 32 is positioned at one focal point of the first elliptic monochromator 38, while the convergence point 44 is on the other focal point. On the other hand, when seen in the Y-direction, the X-ray source 32 is positioned at one focal point of the second elliptic monochromator 40, while the convergence point 44 is on the other focal point. By the way, in FIG. 8B, when X-rays are incident first on any point which is out of the hatching region 42, the reflected X-rays from that point do not impinge on the other elliptic monochromator any longer. Such X-rays can not reach the convergence point 44. Stating in detail, when X-rays are incident first on any point, on the reflecting surface of the first elliptic monochromator 38, which is out of the region 42, the reflected X-rays from that point are focused on a line 46 (parallel to the X-axis). On the other hand, when X-rays are incident first on any point, on the reflecting surface of the second elliptic monochromator 40, which is out of the region 42, the reflected X-rays from that point are focused on a line 48 (parallel to the Y-axis). It is noted that the convergence point 44 is located at the intersection of an extension of the line 46 and an extension of the line 48. If a sample is set on the convergence point 44, only X-rays which are focused in both the YZ-plane and the ZX-plane may irradiate the sample. With the sequential-type composite monochromator as shown in FIG. 8A, a divergence angle, with which X-rays are caught by the composite monochromator, in the YZ-plane is different from a divergence angle in the ZX-plane. On the contrary, with the side-by-side composite monochromator as shown in FIG. 8B, a divergence angle, with which X-rays are caught by the composite monochromator, in the YZ-plane is equal to a divergence angle in the ZX-plane because the distances between the X-ray source 32 and the two monochromators 38 and 40 are equal to each other. Referring to FIG. 11 which illustrates an effect of the focal spot size of an X-ray source, when an X-ray source 32 is positioned at one focal point of the reflecting surface of an elliptic monochromator 24, X-rays emitted from the X-ray source 32 are incident on a point A on the reflecting surface of the elliptic monochromator 24 with an incidence angle .theta.. The incidence angle .theta. depends upon where the X-rays impinge on along the elliptic-arc of the reflecting surface of the elliptic monochromator 24. Because the elliptic monochromator 24 has the graded d-spacing along the curve, the d-spacing, the X-ray wavelength .lambda. of interest and the incidence angle .theta. at any point A satisfy the Bragg equation as described above. By the way, the X-ray source 32 has an apparent focal spot size D as viewed from the point A, and accordingly the incidence angle .theta. at the point A has an angular width .DELTA..theta. (breadth of incidence angle) of a certain extent. As to the breadth .DELTA..theta. the following equation (3) is obtained: EQU D/2=S.multidot.sin(.DELTA..theta./2) (3) where S is the distance between the X-ray source 32 and the point A, and D is the apparent focal spot size of the X-ray source 32. Because .DELTA..theta. is very small, sin(.DELTA..theta./2) is approximately equal to .DELTA..theta./2, noting that the unit for .DELTA..theta. is the radian, and the following equation (4) is obtained: EQU D=S.multidot..DELTA..theta.. (4) Next, the wavelength selectivity of the monochromator will be explained. A graph shown in FIG. 12 indicates the relationship between the incidence angle .theta. of X-rays at the point A and the intensity of the diffracted X-rays (i.e., reflected X-rays) therefrom. The abscissa represents the incidence angle .theta. and the ordinate represents the intensity of the diffracted X-rays. With the monochromator having the synthetic multilayered thin film, the half-value width .epsilon. of the diffraction peak observed is about 0.001 radian. If the breadth .DELTA..theta. of the incidence angle .theta. of incident X-rays is more than the half-value width .epsilon., a portion of X-rays, which has an incidence angle out of the half-value width .epsilon., will not satisfy the Bragg equation so as not to contribute to the diffracted intensity. In the above equation (4), substituting the half-value width .epsilon.=0.001 radian for .DELTA..theta. and 0.5 mm for the focal spot size D leads to that the distance S between the X-ray source and the point A becomes 500 mm. It could be understood that when there is used an X-ray source with an apparent focal spot size of 0.5 mm, the distance S between the X-ray source and the point A should be more than 500 mm for the purpose of narrowing the breadth .DELTA..theta. of the incidence angle .theta. of X-rays at the point A into the above half-value width .epsilon. of the monochromator. If the distance S is less than 500 mm, the breadth .DELTA..theta. of incidence angle, which depends on the X-ray focal spot size, becomes larger than the half-value width .epsilon., so that a portion of the X-rays which are incident on the point A will not satisfy the Bragg equation and will not contribute to the intensity of the diffracted X-rays any longer. Therefore, in FIG. 11, the distance S is required to be more than 500 mm for the purpose of effectively utilizing the intensity of X-rays which are incident on the elliptic monochromator 24. It would be noted further that the minimum distance between the X-ray source 32 and the elliptic monochromator 24 should be more than 500 mm so that the distance S for every point on the reflecting surface of the elliptic monochromator 24 is more than 500 mm. There will now be discussed the divergence angle .alpha. with which X-rays are caught by the elliptic monochromator 24. As the distance between the X-ray source 32 and the elliptic monochromator 24 increases, the divergence angle .alpha. decreases. As the distance decreases, the divergence angle .alpha. increases. Further, as the divergence angle .alpha. increases, the intensity of the X-rays which are focused by the elliptic monochromator 24 increases. Accordingly, for the purpose of increasing the intensity of the focused X-rays, the distance between the X-ray source 32 and the elliptic monochromator 24 should be smaller. However, for the purpose of narrowing the breadth .DELTA..theta. of incidence angle, which depends on the apparent focal spot size D of the X-ray source, into the half-value width .epsilon. mentioned above, the distance between the X-ray source 32 and the elliptic monochromator 24 should be larger. After all, even with the use of the elliptic monochromator, there has been the above-described opposite requirements for the purpose of increasing the intensity of the focused X-rays, so that increasing such an intensity has been limited. Accordingly, an object of the present invention is to provide apparatus for X-ray analysis with which a sample may be irradiated by X-rays of a higher intensity than before in the case of using the elliptic monochromator to focus X-rays on the sample. SUMMARY OF THE INVENTION Investigating the characteristics of the focusing-type synthetic multilayered thin film, we have found what the focal spot size of an X-ray source should be in using such a focusing element. As a result of our investigation, we have confirmed that a combination of a microfocus X-ray tube with a focal spot size of less than 30 micrometers and a focusing-type monochromator with a synthetic multilayered thin film leads to a focused X-ray beam with a good quality and a high intensity which is substantially equal to that in the case of using a 6-kW rotating-anode X-ray generator with a focal spot size of 0.3 mm.times.0.3 mm. Although an X-ray source and a focusing optical element have been considered, in the art, to be separate elements, the present invention provides an integral design comprising of these two elements. Apparatus for X-ray analysis in accordance with the invention is characterized in a combination of a composite elliptic monochromator with a specific structure and a microfocus X-ray source with an apparent focal spot size of less than 30 micrometers. The composite monochromator comprises of a first elliptic monochromator and a second elliptic monochromator. The reflecting surface of the first elliptic monochromator is an elliptic-arc surface with focal axes substantially parallel to the X-direction, while the reflecting surface of the second elliptic monochromator is an elliptic-arc surface with focal axes substantially parallel to the Y-direction. Although it is preferable that the focal axes of the two elliptic monochromator intersect at right angles, it is allowable in practice that the angle of intersection may be apart from right angles within a range of about .+-.10 degrees. The first elliptic monochromator has one side which is connected to one side of the second elliptic monochromator. It is acceptable that the two sides are connected to each other not only with a fitted condition in the longitudinal direction but also with a partly-translated condition of a certain extent (i.e., within a range of about one fourth of the length of the elliptic monochromator) in the longitudinal direction. An X-ray source is positioned at the first focal points of the two elliptic monochromators. A sample is to be set at or near, in the direction of the optical axis, the second focal points of the elliptic monochromators. The sample is not required to be located exactly on the second focal points and is allowed to be located near (namely, in the direction of the optical axis) the second focal point as far as it may be irradiated by X-rays from the monochromator. The first and second elliptic monochromators have synthetic multilayered thin films. The period of the multilayers varies continuously along the elliptic-arc so as to satisfy the Bragg equation for the X-ray wavelength of interest at any point of the reflecting surface. A microfocus X-ray source with an apparent focal spot size of less than 30 micrometers per se is known. For example, an X-ray source with a focal spot size of about 10 to 20 micrometers is disclosed in U.S. Pat. No. 5,020,086. Such a microfocus X-ray source has been utilized for (1) obtaining an enlarged transmission image of a very small region of a sample with an X-ray source being close to the very small region of the sample; and (2) scanning both a sample and a two-dimensional detector and observing the sample while being irradiated by small-spot X-rays, the X-rays being emitted from the X-ray source and focused by a capillary, i.e., an X-ray microscope. The present invention succeeds in increasing an X-ray intensity on a sample by means of combining a composite monochromator comprises two elliptic monochromators having synthetic multilayered thin films and a microfocus X-ray source. In this situation, the characteristics of the microfocus X-ray source (i.e., a very small apparent focal spot size) come in useful. Using the microfocus X-rays with a focal spot size of less than 30 micrometers, even when the distance between the X-ray source and the monochromator becomes smaller, the breadth .DELTA..theta. of incidence angle, which depends upon the apparent focal spot size of the X-ray source, becomes within the range of the half-value width .epsilon. of the diffraction peak of the elliptic monochromator, so that the X-rays reaching the elliptic monochromator are utilized effectively with no loss. Furthermore, because the distance between the X-ray source and the elliptic monochromator can be smaller in the invention, the capture angle .alpha. of incident X-rays on the elliptic monochromator is increased, for example, the capture solid angle may be more than 0.0005 steradian, so that the X-ray intensity on the second focal point can be greatly increased than before. The advantage of the present invention will now be described in detail. It will be understood from the below description that a higher X-ray intensity is obtained on the sample by using, in case of being combined with the composite monochromator, not the normal-focus or the fine-focus X-ray sources but the microfocus X-ray source which has a very small X-ray power as compared with the normal-focus or the fine-focus X-ray sources. That is to say, we have discovered a combination of the microfocus X-ray source with a very high brightness and the composite elliptic monochromator so arranged that it can take a large capture angle. Considering the condition that divergent X-rays are effectively focused by the focusing composite elliptic monochromator, a capture solid angle .OMEGA. for incident X-rays on the composite elliptic monochromator is expressed by EQU .OMEGA.=.alpha..sup.2 =A/S.sup.2 (5) where .alpha. is the divergence angle of incident X-rays on the composite monochromator, A is the apparent area of the composite monochromator, and S is the distance between the focal spot of the X-ray source and the composite monochromator. The X-ray intensity I on a sample is expressed by I=.eta.P.OMEGA. (6) where .eta. is the optical efficiency of the focusing composite monochromator for the X-ray intensity I on the sample, and P is the power (i.e., the effective total dose) of the X-ray source. The focal spot size D of the X-ray source is expressed by EQU D.apprxeq.S.multidot..DELTA..theta. (7) where .DELTA..theta. is the breadth of the incidence angle of X-rays, noting that the breadth .DELTA..theta. in this equation should be equal to the half-value width .epsilon. of the diffraction peak observed with the composite monochromator so that incident X-rays within the breadth .DELTA..theta. can be effectively reflected by the composite monochromator. The brightness B (i.e., the X-ray power per unit area) of the X-ray source is expressed by EQU B=P/D.sup.2. (8) Accordingly, EQU I=.eta.P.OMEGA.=.eta.PA/S.sup.2 =.eta.BA.multidot..DELTA..theta..sup.2. (9) Therefore, if the same composite monochromator is used, .eta., A, and .DELTA..theta. become constant, and the X-ray intensity I becomes essentially proportional to the brightness B of the X-rays. On the other hand, the possible brightness B of the X-ray source depends on both thermal limitation and electronic limitation. When the focal spot size of the X-ray source becomes very small, the electronic limitation becomes dominant. On the contrary, if the focal spot size of the X-ray source becomes not so small, the thermal limitation is dominant. The practical microfocus X-ray source in the art would have a possible minimum focal spot size of down to about 1 to 2 micrometers, with the technical improvement, in the case of using both the electronic gun and the electromagnetic lens. The electronic limitation would be dominant for the focal spot size of less than about 2 micrometers. Accordingly, for the focal spot size of more than about 2 micrometers, only the thermal limitation may be taken in account for defining the relationship between the focal spot size and the brightness of the X-ray source. The allowable input power P' of an X-ray source can be calculated in general by Muller's equation, the allowable power P' depending upon the material, shape and thermal condition of the X-ray target. The possible output power P (i.e., the X-ray intensity) of the X-ray source would be proportional to the allowable input power P' in the same condition. The allowable input power P' can be calculated by EQU P'.apprxeq.4.25.kappa.T.sub.m W/2 (10) where .kappa. is the thermal conductivity of the target material, T.sub.m is the temperature difference between the allowable maximum temperature of the focal spot surface and the cooled surface of the target, and W is the length of one side of a square focal spot on which an electron beam impinges at right angles. Assuming that the target material is copper and the shape of the focal spot on the target is a point focus, the allowable input power P' for the focal spot size is shown in Table 1. TABLE 1 Focal Spot Size P' (W) B' (W/mm.sup.2) Normal Focus 1 mm .times. 1 mm 750 750 Fine Focus 0.1 mm .times. 0.1 mm 75 7500 Microfocus 0.01 mm .times. 0.01 mm 7.5 75000 In Table 1, B' is the brightness which is observed in a direction perpendicular to the target surface of the X-ray source, the value of B' being obtained by dividing P' by the incident-electron-beam spot area which is substantially equal to the focal spot area of the X-ray source. The indicated value of B' for each focal spot size has been confirmed experimentally. The apparent focal spot size D and the apparent brightness B of the X-rays emitted from an X-ray source, even for the same electron-beam spot size W on the target, vary with the take-off angle. As shown in FIG. 2B, even for the line focus on the target, when taking an X-ray beam in the illustrated direction, the resultant X-ray beam is to be emitted from an apparent point focus. For example, assuming that the line focus on the target shown in FIG. 2B has a size of W.sub.1 =0.01 mm and W.sub.2 =0.1 mm, i.e., the microfocus line focus, we can obtain a microfocus X-ray beam emitted from an apparent point focus with an apparent focal spot size of D.sub.1 =W.sub.1 =0.01 mm and D.sub.2 =W.sub.2 sin(6 degrees)=0.01 mm when taking X-rays in the illustrated direction. The allowable input power P' for the apparent point focus with the take-off angle of 6 degrees is shown in Table 2. TABLE 2 Focal Spot Size P' (W) B (W/mm.sup.2) Normal Focus 1 mm .times. 1 mm 3180 3180 Fine Focus 0.1 mm .times. 0.1 mm 318 31800 Microfocus 0.01 mm .times. 0.01 mm 31.8 318000 In Table 2, B is the brightness which is observed in the direction of the take-off angle of about 6 degrees, the value of B being obtained, as an approximate value, by dividing P' by the apparent focal spot area. The normal-focus X-ray source typically has an allowable input power P.sub.a of about 3 kW and a brightness B of about 3000 W/mm.sup.2, while the microfocus X-ray source has, although depending on the focus shape, an allowable input power P' of about 30 W as shown in Table 2, which has been obtained experimentally as an approximate value, and a brightness B of about 300 kW/mm.sup.2 which is 100 times higher than that in the normal-focus. As the focal spot size decreases, within the range of down to about 2 micrometers, the brightness B increases and accordingly the X-ray intensity I on the sample also increases as indicated in the equation (9). It is noted therefore that a combination of the composite elliptic monochromator and the microfocus X-ray source having a very small power leads to a greatly increased X-ray intensity on the sample as compared with the prior art. The apparent focal spot size of an X-ray source is defined by the maximum span across the focal spot image as viewed from the elliptic monochromator. The present invention is effective in the case of the apparent focal spot size of less than 30 micrometers, and preferably within the range of 2 to 20 micrometers, and typically about 10 micrometers. With the present invention, the minimum distance between the focal spot of an X-ray target and the composite monochromator can be less than 50 mm, and preferably less than 30 mm, and more preferably about 10 to 20 mm. It is noted that the lower limit value of the minimum distance would depend upon, in general, structural restrictions of the X-ray tube. The elliptic monochromator used in this invention has an extremely compressed shape, so that an X-ray source, which is to be located on the focal point of the ellipse, can be close to the elliptic monochromator. The main feature of the apparatus for X-ray analysis of the invention is directed to the X-ray supplying system which is arranged between an X-ray source and a sample, so that an optical system between the sample and a detector has no restrictions in the invention. For example, when X-rays emitted from the microfocus X-ray source are focused by the composite monochromator on a sample and the diffracted X-rays from the sample are detected, such apparatus for X-ray analysis according to the invention becomes an X-ray diffraction system. On the other hand, when the fluorescence X-rays from the sample are detected, such apparatus for X-ray analysis according to the invention becomes a fluorescence X-ray analysis system.
055240410	summary	This invention generally concerned with a collimator for removing unwanted divergent beams of radiation received from a source, leaving a well resolved radiation beam for detection and analysis. More particularly, the invention is directed to a collimator having a layered structure for removing not only unwanted angularly divergent radiation beams, but also for removing radiation inelastically scattered by the collimator structure itself. Radiographic imaging methods and apparatus are undergoing rapid evolution as efforts are being made to improve the ability to image selected portions of a specimen or diffract and sense radiation from the specimen. The effectiveness of these various methodologies and even the ability to use certain techniques depends primarily on spatial resolution and on the associated signal to noise ratio in the data being accumulated. Present technology is able to generate a radiation intensity adequate to image and evaluate structure and analyze a number of abnormalities. However, current technology cannot effectively collimate this radiation intensity without counting certain divergent radiation and thus including substantial unwanted noise in the resulting data. Such divergent, unwanted signal derives, for example, from radiation which has been inelastically scattered from the collimator structure itself. This deficiency therefore requires exposing the specimen to larger intensities of radiation in order to achieve a desired resolution. Unfortunately, such increased radiation exposure can be hazardous, and moreover there are some divergent radiation sources whose deleterious effects cannot be alleviated even by increasing the radiation signal level. It is therefore an object of the invention to provide an improved method of manufacture and method for collimation of radiation. It is another object of the invention to provide a new method of manufacture of a collimator for a radiation beam. It is a further object of the invention to provide an improved collimating device for removing divergent radiation beams received from, or passed through, a specimen undergoing diagnostic analysis. It is an additional object of the invention to provide a new radiation collimator assembly for providing highly resolved, high intensity data characteristic of a specimen but without having to increase exposure to radiation. It is yet another object of the invention to provide an improved radiation collimator assembly having a layered wall material structure for substantially reducing inelastic scattered radiation present in the detected data signal. It is still a further object of the invention to provide a new collimator having a lead base structure with an outer layer of a material which preferentially absorbs X-rays generated from inelastic scattering of gamma rays from the lead base collimator structure. It is yet an additional object of the invention to provide a radiation collimator having a selectable collimator length using a stack of different predetermined height collimator units. It is still a further object of the invention to provide a gamma ray collimator of lead with a thin tin layer on the collimator walls to absorb lead X-rays generated by inelastic gamma ray scattering from the lead collimator. Other objects, features and advantages of the present invention will be readily apparent from the following description of the preferred embodiments thereof, taken in conjunction with the accompanying drawings described below wherein like elements have like numerals throughout the several views.
062748777	abstract	Blurring of an electron beam image produced by the Coulomb effect upon forming a pattern on a substrate by exposure using a multi-electron beam exposure apparatus is corrected. The electron beam exposure apparatus has an elementary electron optical system array for generating a plurality of electron beams in accordance with the pattern to be exposed, a reduction electron optical system for imaging the electron beams coming from the elementary electron optical system array, a deflector for deflecting the electron beams, and a focal point/astigmatism control circuit for correcting the imaging positions of the electron beams in units of settling positions of the electron beams on the basis of correction data corresponding to the pattern to be exposed.
	claims	1. A projection-optical system for projecting an image of a pattern from a first surface onto a second surface, the system comprising:a first reflector and a second reflector situated along a light-propagation path extending from the first surface to the second surface, whereinthe first reflector has a reflectance, for light of a predetermined wavelength, that is less than a predetermined reflectance;the second reflector has a reflectance, for light of the predetermined wavelength, that is greater than the predetermined reflectance; andalong the light-propagation path the first reflector is situated closer than the second reflector to the first surface. 2. The system of claim 1, further comprising at least one additional reflector, wherein, along the light-propagation path, the first reflector is closest to the first surface. 3. The system of claim 1, wherein the reflectance of the first reflector to light of the predetermined wavelength is less than half the reflectance of the second reflector to light of the predetermined wavelength. 4. The system of claim 1, wherein the first reflector comprises a layer configured to absorb light of the predetermined wavelength. 5. The system of claim 4, wherein;the first reflector further comprises a multilayer film; andthe layer configured to absorb light of the predetermined wavelength is situated on the multilayer film. 6. The system of claim 4, wherein the layer configured to absorb light of the predetermined wavelength comprises a material selected from the group consisting of silicon dioxide, carbon, zirconium, silicon carbide, silicon nitride, boron carbide, boron nitride, and combinations thereof. 7. The system of claim 1, wherein:the first reflector comprises (i) a multilayer film and (ii) a layer or membrane disposed on the multilayer film;the multilayer film has a reflective surface, and the layer or membrane has a reflective surface; andthe reflective surface of the multilayer film is inclined relative to the reflective surface of the layer or membrane. 8. The system of claim 7, wherein the layer or membrane comprises a material selected from the group consisting of silicon, silicon carbide, silicon nitride, and combinations thereof. 9. The system of claim 1, configured to use exposure light, having a wavelength different from the predetermined wavelength, for projecting an image of the pattern on the first surface onto the second surface, wherein the predetermined reflectance is reflectance to the exposure light. 10. The system of claim 9, wherein the exposure light is EUV light. 11. An exposure apparatus, comprising a projection-optical system as recited in claim 1. 12. A microelectronic-device manufacturing process, comprising:(a) preparing a substrate;(b) processing the substrate; and(c) assembling microelectronic devices formed on the substrate during steps (a) and (b), wherein step (b) comprises the steps of (i) applying a resist to the substrate; (ii) exposing the resist; and (iii) developing the resist; and step (ii) comprises providing a exposure apparatus as recited in claim 11, and using the exposure apparatus to expose the resist with the pattern defined on the reticle. 13. A projection-optical system for projecting an image of a pattern from a first surface onto a second surface, the system comprising:a first reflector and a second reflector situated along a light-propagation path extending from the first surface to the second surface, whereinthe first reflector has a reflectance, for light of a predetermined wavelength, that is less than a predetermined reflectance;the second reflector has a reflectance, for light of the predetermined wavelength, that is greater than the predetermined reflectance; andalong the light-propagation path the second reflector is situated at a location of maximal illuminance. 14. The system of claim 13, further comprising at least one additional reflector, wherein:along the light-propagation path at least one reflector of the system is situated closer than the second reflector to the first surface; andthe at least one reflector situated closer to the first surface includes the first reflector. 15. The system of claim 13, further comprising at least one additional reflector, wherein, along the light-propagation path and among the reflectors of the system, the reflector situated closest to the first surface is the first reflector. 16. The system of claim 13, further comprising at least one additional first reflector, wherein, along the light-propagation path the first reflectors are situated closer than the second reflector to the first surface. 17. The system of claim 13, wherein the reflectance of the first reflector to light of the predetermined wavelength is less than half the reflectance of the second reflector to light of the predetermined wavelength. 18. The system of claim 13, configured to use exposure light, having a wavelength different from the predetermined wavelength, for projecting an image of the pattern on the first surface onto the second surface, wherein the predetermined reflectance is reflectance to the exposure light. 19. The system of claim 18, wherein the exposure light is EUV light. 20. The system of claim 13, wherein the first reflector comprises a layer configured to absorb light of the predetermined wavelength. 21. The system of claim 20, wherein;the first reflector further comprises a multilayer film; andthe layer configured to absorb light of the predetermined wavelength is situated on the multilayer film. 22. The system of claim 20, wherein the layer configured to absorb light of the predetermined wavelength comprises a material selected from the group consisting of silicon dioxide, carbon, zirconium, silicon carbide, silicon nitride, boron carbide, boron nitride, and combinations thereof. 23. The system of claim 13, wherein:the first reflector comprises (i) a multilayer film and (ii) a layer or membrane disposed on the multilayer film;the multilayer film has a reflective surface, and the layer or membrane has a reflective surface; andthe reflective surface of the multilayer film is inclined relative to the reflective surface of the layer or membrane. 24. The system of claim 23, wherein the layer or membrane comprises a material selected from the group consisting of silicon, silicon carbide, silicon nitride, and combinations thereof. 25. An exposure apparatus, comprising a projection-optical system as recited in claim 13. 26. A microelectronic-device manufacturing process, comprising:(a) preparing a substrate;(b) processing the substrate; and(c) assembling microelectronic devices formed on the substrate during steps (a) and (b), wherein step (b) comprises the steps of (i) applying a resist to the substrate; (ii) exposing the resist; and (iii) developing the resist; and step (ii) comprises providing a exposure apparatus as recited in claim 25, and using the exposure apparatus to expose the resist with the pattern defined on the reticle. 27. A projection-optical system for projecting an image of a pattern from a first surface onto a second surface, the system comprising:multiple reflectors situated along a light-propagation path extending from the first surface to the second surface, the reflectors including a first reflector and a second reflector, whereinthe first reflector has a reflectance, for light of a predetermined wavelength, that is less than a predetermined reflectance;the second reflector has a reflectance, for light of the predetermined wavelength, that is greater than the predetermined reflectance; andalong the light-propagation path the second reflector is situated in a vicinity of a location at which an intermediate image is formed by the system. 28. The system of claim 27, further comprising at least one additional reflector, wherein:along the light-propagation path at least one reflector of the system is situated closer than the second reflector to the first surface; andthe at least one reflector situated closer to the first surface includes the first reflector. 29. The system of claim 27, further comprising at least one additional reflector, wherein, along the light-propagation path and among the reflectors of the system, the first reflector is situated closest to the first surface. 30. The system of claim 27, wherein:the system comprises multiple first reflectors; andalong the light-propagation path and among the reflectors of the system, the first reflectors are situated closer than the second reflector to the first surface. 31. The system of claim 27, wherein the reflectance of the first reflector to light of the predetermined wavelength is less than half the reflectance of the second reflector to light of the predetermined wavelength. 32. The system of claim 27, configured to use exposure light, having a wavelength different from the predetermined wavelength, for projecting an image of the pattern on the first surface onto the second surface, wherein the predetermined reflectance is reflectance to the exposure light. 33. The system of claim 32, wherein the exposure light is EUV light. 34. The system of claim 27, wherein the first reflector comprises a layer configured to absorb light of the predetermined wavelength. 35. The system of claim 34, wherein;the first reflector further comprises a multilayer film; andthe layer configured to absorb light of the predetermined wavelength is situated on the multilayer film. 36. The system of claim 34, wherein the layer configured to absorb light of the predetermined wavelength comprises a material selected from the group consisting of silicon dioxide, carbon, zirconium, silicon carbide, silicon nitride, boron carbide, boron nitride, and combinations thereof. 37. The system of claim 27, wherein:the first reflector comprises (i) a multilayer film and (ii) a layer or membrane disposed on the multilayer film;the multilayer film has a reflective surface, and the layer or membrane has a reflective surface; andthe reflective surface of the multilayer film is inclined relative to the reflective surface of the layer or membrane. 38. The system of claim 37, wherein the layer or membrane comprises a material selected from the group consisting of silicon, silicon carbide, silicon nitride, and combinations thereof. 39. An exposure apparatus, comprising a projection-optical system as recited in claim 27. 40. A microelectronic-device manufacturing process, comprising:(a) preparing a substrate;(b) processing the substrate; and(c) assembling microelectronic devices formed on the substrate during steps (a) and (b), wherein step (b) comprises the steps of (i) applying a resist to the substrate; (ii) exposing the resist; and (iii) developing the resist; and step (ii) comprises providing a exposure apparatus as recited in claim 39, and using the exposure apparatus to expose the resist with the pattern defined on the reticle. 41. A projection-optical system for projecting an image of a pattern from a first surface onto a second surface, the system comprising:multiple reflectors situated along a light-propagation path extending from the first surface to the second surface, the multiple reflectors including a first reflector and a second reflector, whereinthe first reflector has a reflectance, for light of a predetermined wavelength, that is less than a predetermined reflectance;the second reflector has a reflectance, for light of the predetermined wavelength, that is greater than the predetermined reflectance;with respect to each of the reflectors of the system, (i) a first point-reflecting region is a region, on the reflector, at which a light beam collected at a predetermined first point on the second surface is reflected, (ii) a second point-reflecting region is a region, on the reflector, at which a light beam collected at a second point, different from the first point, on the second surface is reflected, and (iii) a common-reflecting region is a region, on the reflector, in which the first point-reflecting region and the second point-reflecting region overlap;of the multiple reflectors of the system, a subset comprises reflectors each having a respective common-reflection region in which a portion corresponding to the first point-reflecting region is lower than a predetermined percentage; andone of the reflectors in the subset is the second reflector that is situated, along the light-propagation path, closest to the first surface of all the reflectors in the subset. 42. The system of claim 41, wherein:the multiple reflectors further comprise at least one additional reflector;at least one reflector is situated, along the light-propagation path, closer to the first surface than the second reflector in the subset; andthe at least one closer reflector includes the first reflector. 43. The system of claim 41, wherein:the multiple reflectors further comprise at least one additional reflector; andalong the light-propagation path and of the reflectors in the system, the first reflector is situated closest to the first surface. 44. The system of claim 41, wherein:the multiple reflectors comprise multiple first reflectors and at least one additional reflector; andalong the light-propagation path and of the reflectors in the system, the first reflectors are situated closest to the first surface. 45. The system of claim 41, wherein all reflectors, having respective common-reflection regions in which respective portions corresponding to the first point-reflecting region are lower than the predetermined percentage, are second reflectors. 46. The system of claim 41, wherein at least one of the reflectors, having respective common-reflection regions in which respective portions corresponding to the first point-reflecting region are lower than the predetermined percentage, is a first reflector. 47. The system of claim 41, wherein all reflectors, having respective common-reflection regions in which respective portions corresponding to the first point-reflecting region are higher than the predetermined percentage, are first reflectors. 48. The system of claim 41, further defining an arc-shaped exposure region of a predetermined width, wherein:the first point-reflection region is a first end of an arc passing through a widthwise center of the arc-shaped exposure region;the second point-reflection region is a second end of the arc passing through the widthwise center of the arc-shaped exposure region;among the reflectors having respective common-reflection regions in which respective portions corresponding to the first point-reflecting region are lower than the predetermined percentage, the reflector situated closest, along the light-propagation path, to the first surface is a second reflector. 49. The system of claim 48, wherein:among the reflectors, having respective common-reflection regions in which respective portions corresponding to the first point-reflecting region are lower than the predetermined percentage, is at least one deflector of which the percentage of the common-reflection region corresponding to the first point-reflecting region is substantially zero; andthe reflector situated closest, along the light-propagation path, to the first surface is the second reflector. 50. The system of claim 41, configured to use exposure light, having a wavelength different from the predetermined wavelength, for projecting an image of the pattern on the first surface onto the second surface, wherein the predetermined reflectance is reflectance to the exposure light. 51. The system of claim 50, wherein the exposure light is EUV light. 52. The system of claim 41, wherein the reflectance of the first reflector to light of the predetermined wavelength is less than half the reflectance of the second reflector to light of the predetermined wavelength. 53. The system of claim 41, wherein the first reflector comprises a layer configured to absorb light of the predetermined wavelength. 54. The system of claim 53, wherein;the first reflector further comprises a multilayer film; andthe layer configured to absorb light of the predetermined wavelength is situated on the multilayer film. 55. The system of claim 53, wherein the layer configured to absorb light of the predetermined wavelength comprises a material selected from the group consisting of silicon dioxide, carbon, zirconium, silicon carbide, silicon nitride, boron carbide, boron nitride, and combinations thereof. 56. The system of claim 41, wherein:the first reflector comprises (i) a multilayer film and (ii) a layer or membrane disposed on the multilayer film;the multilayer film has a reflective surface, and the layer or membrane has a reflective surface; andthe reflective surface of the multilayer film is inclined relative to the reflective surface of the layer or membrane. 57. The system of claim 56, wherein the layer or membrane comprises a material selected from the group consisting of silicon, silicon carbide, silicon nitride, and combinations thereof. 58. An exposure apparatus, comprising a projection-optical system as recited in claim 41. 59. A microelectronic-device manufacturing process, comprising:(a) preparing a substrate;(b) processing the substrate; and(c) assembling microelectronic devices formed on the substrate during steps (a) and (b), wherein step (b) comprises the steps of (i) applying a resist to the substrate; (ii) exposing the resist; and (iii) developing the resist; and step (ii) comprises providing a exposure apparatus as recited in claim 58, and using the exposure apparatus to expose the resist with the pattern defined on the reticle. 60. A projection-optical system for projecting an image of a pattern from a first surface onto a second surface, the system comprising along a light-propagation path from the first surface to the second surface:a first reflector having a particular reflectance for light of a predetermined wavelength; anda second reflector having a reflectance, greater than the reflectance of the first reflector, for light of the predetermined wavelength. 61. The system of claim 60, wherein the first reflector is situated, along the light-propagation path, closer than the second reflector to the first surface. 62. The system of claim 60, comprising multiple reflectors, including at least one first reflector and at least one second reflector, along the light-propagation path, wherein a first reflector is situated closest to the first surface. 63. The system of claim 60, wherein:the first reflector and the second reflector have respective illuminances; andthe illuminance at the first reflector is less than the illuminance at the second reflector. 64. The system of claim 60, wherein the second reflector is situated, along the light-propagation path, at a location at which illuminance is highest. 65. The system of claim 60, wherein:the system is configured to form, at a location along the light-propagation path, an intermediate image; andthe second reflector is located in the vicinity of the intermediate-image location. 66. The system of claim 60, wherein, with respect to each of the reflectors of the system;a first point-reflecting region is a region, on the reflector, at which a light beam collected at a predetermined first point on the second surface is reflected;a second point-reflecting region is a region, on the reflector, at which a light beam collected at a second point, different from the first point, on the second surface is reflected;a common-reflecting region is a region, on the reflector, in which the first point-reflecting region and the second point-reflecting region overlap;a common-region percentage is the percentage of the common-reflecting region corresponding to the first point-reflecting region; andthe common-region percentage of the first reflector is higher than the common-region percentage of the second reflector. 67. The system of claim 66, further defining an arc-shaped exposure region of a predetermined width, wherein:the first point-reflection region is a first end of an arc passing through a widthwise center of the arc-shaped exposure region; andthe second point-reflection region is a second end of the arc passing through the widthwise center of the arc-shaped exposure region. 68. The system of claim 67, wherein:multiple reflectors of the system have respective common-region percentages of substantially zero; andamong the reflectors having substantially zero common-region percentages, the reflector that is situated closest, along the light-propagation path, to the first surface is a second reflector. 69. The system of claim 60, configured to utilize an exposure light, having a wavelength different from the predetermined wavelength, for projection of an image of the pattern on the first surface onto the second surface. 70. The system of claim 69, wherein the exposure light is EUV light. 71. The system of claim 60, wherein the reflectance of the first reflector to light of the predetermined wavelength is less than half the reflectance of the second reflector to light of the predetermined wavelength. 72. The system of claim 60, wherein the first reflector comprises a layer configured to absorb light of the predetermined wavelength. 73. The system of claim 72, wherein;the first reflector further comprises a multilayer film; andthe layer configured to absorb light of the predetermined wavelength is situated on the multilayer film. 74. The system of claim 73, wherein the layer configured to absorb light of the predetermined wavelength comprises a material selected from the group consisting of silicon dioxide, carbon, zirconium, silicon carbide, silicon nitride, boron carbide, boron nitride, and combinations thereof. 75. The system of claim 60, wherein:the first reflector comprises (i) a multilayer film and (ii) a layer or membrane disposed on the multilayer film;the multilayer film has a reflective surface, and the layer or membrane has a reflective surface; andthe reflective surface of the multilayer film is inclined relative to the reflective surface of the layer or membrane. 76. The system of claim 75, wherein the layer or membrane comprises a material selected from the group consisting of silicon, silicon carbide, silicon nitride, and combinations thereof. 77. An exposure apparatus, comprising a projection-optical system as recited in claim 60. 78. A microelectronic-device manufacturing process, comprising:(a) preparing a substrate;(b) processing the substrate; and(c) assembling microelectronic devices formed on the substrate during steps (a) and (b), wherein step (b) comprises the steps of (i) applying a resist to the substrate; (ii) exposing the resist; and (iii) developing the resist; and step (ii) comprises providing a exposure apparatus as recited in claim 77, and using the exposure apparatus to expose the resist with the pattern defined on the reticle.
047117575	description	DESCRIPTION OF THE PREFERRED EMBODIMENTS The circuit shown in FIG. 1 includes a plurality of sensing coils L, each bearing a respective designation Ln, where n represents the spatial position of the respective coil along the path being monitored, starting from the lowest point of the path. Thus, coil L1 is at the lowest point of the path and coil L22 is at the highest point. Coils L are annular in form and are arranged so that each coil surrounds the path being monitored and permits passage of a member made of a material which can influence the effective impedance of each coil L. The coil array further includes two coils P, bearing respective designations P1 and P2. Coils P are located outside of the path being monitored. Preferably, all coils L, P are electrically and physically identical. The coils are connected in series pairs, as shown, with each pair being connected between a.c. supply voltage terminals 36 and 38. A voltage divider composed of two resistors 40 and 42 is also connected between terminals 36 and 38. Resistors 40 and 42 can have identical resistance values. The circuit further includes eight differential amplifiers 51 to 58, each having a signal input 60, a reference input 62, an output 64 and a feedback resistor 66 connected between signal input 60 and output 64. The reference input 62 of each differential amplifier is connected to the connection point 68 between resistors 40 and 42 to receive a reference voltage. Each pair of coils L, L and L, P has a connection point, or center tap, at which a voltage equal to the voltage at connection point 68 appears when both coils have the same effective impedance. This will occur if the impedance-influencing member is in a position in which it influences the impedances of both coils of a pair equally or in which it does not influence the impedance of either coil of the pair. On the other hand, if the impedance-influencing element is in a position where it influences the impedance of only one coil of a pair, then a voltage imbalance occurs between the coils of the pair and the voltage at the associated connection point will differ from that at connection point 68. The connection point between each pair of coils is connected via a respective resistor 72 to the signal input 60 of a respective one of amplifiers 51-58. It will be noted that in the illustrated circuit, the coils which are connected electrically to form a coil pair are not spatially directly adjacent one another along the path being monitored. For example, the coils at positions 1 and 3 (L1 and L3) form an electrically connected pair, as do those at positions 8 and 11 (L8 and L11). As a general rule, the coils of a given coil pair should be separated from one another by no more than three intervening coils associated with other coil pairs. Therefore, after the impedance-influencing member produces a voltage imbalance across one coil pair, resulting in a voltage representing a logic "1" at the associated connection point, this imbalance will be maintained when, during further member travel, an imbalance has been produced at at least the next succeeding coil pair. This relationship, which has been previously proposed, will be described in greater detail below. The outputs 64 of amplifiers 51-58 provide a parallel eight-bit Gray code representing the current position of the impedance-influencing element along the path being monitored. According to a novel feature of the invention, one or more of differential amplifiers 51-58 has its signal input 60 connected to more than one connection point via respective resistors 72. This means that the value of at least one output bit is influenced by movement of the impedance-influencing member along several portions of the path being monitored. This enables the position responses of the detector circuit to be directly coded into a suitabale eight-bit Gray code. FIG. 1 shows only one possible coding pattern according to the invention. Other patterns can be produced by changing the connection arrangements between center points and amplifier inputs 60. If the coils of each coil pair are electrically balanced when both coils are either fully penetrated or not penetrated at all by the impedance-influencing member, no interaction will occur betwee the multiple inputs to any one differential amplifier. The electrical separation of the inputs to a differential amplifier is further enhanced by connecting each differential amplifier to coil pairs which are physically separated to such an extent that, at any given time, only one of the coil pairs connected to a given amplifier will be unbalanced. The number of positions to be monitored can be varied by providing a suitable number of sensing coils, electrically connected in coil pairs, and by connecting the coil pair center points in an appropriate pattern to the eight amplifiers 51-58. FIG. 2 is a pictorial elevational view showing the lower portion of the sensing coil assembly of FIG. 1 and the upper portion of a control rod drive line 76 penetrating the four lowest coils L1-L4. Each coil has the same designation "Ln" as in FIG. 1 and the coils are spatially arranged in order of their respective "n" designations. The center point connections between electrically connected coil pairs are shown along the left-hand side of FIG. 2. At least the upper portion of line 76 is made of a material selected to vary the effective impedance of each coil which it penetrates and constitutes the abovementioned impedance-influencing member. In the position illustrated, line 76 fully penetrates coils L1 and L3 so that this electrically connected coil pair is electrically balanced and the potential at its center connection point has a value representing logic "0". While coils L2 and L4 are also penetrated by line 76, coils L5 and L7 are not. Therefore, coil pairs L2, L5 and L4, L7 are electrically unbalanced and the potentials at their respective center connection points have a value representing logic "1". Finally, all coils above coil L4 are not penetrated by drive line 76 so that all remaining coil pairs are electrically balanced. Therefore, reverting to FIG. 1, when drive line 76 is in the position shown in FIG. 2, amplifiers 52 and 53 will produce a logic "1" output and all other amplifiers will produce a logic "0" output. If the upper end of drive line 76 moves upwardly to penetrate coil L5, coil pair L2, L5 is no longer unbalanced and amplifier 52 then produces a logic "0" output. When the upper end of drive line 76 is below coil L1 so that no coil is penetrated, all coil pairs are electrically balanced so that all amplifiers 51-58 produce a logic "0" output. On the other hand, when the upper end of drive line 76 is at the highest point of the path being monitored, so that all L coils are penetrated, coils P1 and P2 are not penetrated. Therefore, coil pairs L20, P1 and L21, P2 are electrically unbalanced and cause amplifiers 53 and 56 to produce logic "1" outputs. As a result, the monitoring circuit is capable of distinguishing between the situation in which all L coils are penetrated and that in which no L coil is penetrated. The logic outputs provided by amplifiers 51-58 for all positions of the upper end of drive line 76 are shown in the following Table, where the top of drive line 76 is below coil L1 in POSITION 0, penetrates only coil L1 in POSITION 1, etc. and penetrates all L coils in POSITION 22. ______________________________________ POSITION 58 57 56 55 54 53 52 51 ______________________________________ 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 1 2 0 0 0 0 0 0 1 1 3 0 0 0 0 0 0 1 0 4 0 0 0 0 0 1 1 0 5 0 0 0 0 0 1 0 0 6 0 0 0 0 1 1 0 0 7 0 0 0 0 1 0 0 0 8 0 0 0 1 1 0 0 0 9 0 0 0 1 0 0 0 0 10 0 0 1 1 0 0 0 0 11 0 0 1 0 0 0 0 0 12 0 0 1 0 0 0 0 1 13 0 0 1 0 1 0 0 1 14 0 0 0 0 1 0 0 1 15 0 1 0 0 1 0 0 1 16 0 1 0 0 1 0 0 0 17 0 1 0 0 0 0 0 0 18 1 1 0 0 0 0 0 0 19 1 0 0 0 0 0 0 0 20 1 0 0 0 0 1 0 0 21 1 0 1 0 0 1 0 0 22 0 0 1 0 0 1 0 0 ______________________________________ The binary values shown in the preceding Table, which appear at the outputs of amplifiers 51-58, thus constitute an 8-bit Gray code identifying the position of the upper end of drive line 76. It will be understood that the above description of the present invention is susceptible to various modifications, changes and adaptations, and the same are intended to be comprehended within the meaning and range of equivalents of the appended claims.
	abstract	An apparatus to examine a target in a patient includes an x-ray source configured to deliver a first x-ray beam towards the target, a device having an array of openings, the device located at an angle less than 180 degrees relative to a beam path of the first x-ray beam to receive a second x-ray beam resulted from an interaction between the first x-ray beam and the target, and a detector aligned with the device, the detector located at an angle less than 180 degrees relative to the beam path of the first x-ray beam to receive a part of the second x-ray beam from the device that exits through the openings at the device.
	summary

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