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abstract | The invention relates to a process for the preparation of a product based on a phosphate of at least one element M(IV), for example of thorium and/or of actinide(IV)(s). |
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claims | 1. A waveguide of a microwave ion source, comprising:an elongated waveguide main body of the microwave ion source, the elongated waveguide main body being made of a material selected from the group consisting of a boron nitride and an aluminum oxide; anda thin film defining a microwave path made of a titanium nitride covering an outer peripheral surface of the waveguide main body, wherein the outer peripheral surface of the waveguide main body is bonded to the thin film. 2. waveguide according to claim 1, wherein the waveguide main body is made of a boron nitride. 3. The waveguide according to claim 1, wherein the outer peripheral surface of the waveguide main body is bonded to the thin film. 4. The waveguide according to claim 1, wherein the waveguide main body is made of an aluminum oxide. 5. The waveguide according to claim 1, wherein the waveguide main body has a wedge shape. 6. The waveguide according to claim 1, wherein the thin film is formed by a CVD method. 7. waveguide according to claim 1, wherein the thin film has a thickness of 10 to 500 μm. 8. The waveguide according to claim 1, wherein the thin film has a thickness of 200 μm. 9. The waveguide according to claim 1, wherein a reflection of an electromagnetic wave on the outer peripheral surface of the waveguide main body is suppressed. |
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description | This application claims the benefit of U.S. Provisional Application No. 62/151,566 filed Apr. 23, 2015, which is incorporated herein by reference in its entirety. The present invention relates generally to nuclear fuel assembly, and more particularly to a highly portable device and related method for controlling the reactivity of a fuel assembly outside of the nuclear reactor vessel. Most high capacity dry storage canisters used to store commercial nuclear fuel, such as MPC-32 in the HI-STORM 100 system (USNRC Docket #72-1014) are of the so-called Non-flux trap (NFT) type which means a single panel of neutron absorber lies between two facing fuel assemblies. The storage cells are thus tightly packed and the number of fuel assembles that can be accommodated in a cask (or canister) of a given cross section is maximized. These high capacity fuel baskets, however, suffer from the demerit that they do not meet the NRC's (Nuclear Regulatory Commission's) sub-criticality criterion (reactivity multiplier <0.95 with all uncertainties and biases factored in with 95% confidence and 95% certainty) for fresh fuel of a relatively high initial enrichment (say, 5 w/0 U-235). Even the most modern PWR fuel basket, such as the one in MPC-37 (NRC Docket #72-1032) cannot satisfy the above criticality requirement for the largest commercial PWR fuel assemblies in spite of the fact that it features neutron absorber panels with substantially greater boron areal concentration that older basket designs. Areal density of boron is the direct indicator of the neutron absorption capacity of a neutron absorber. This deficit in the neutron absorption ability of the high capacity fuel basket is overcome by relying on the soluble boron in the fuel pool's water (permitted under USNRC's 10 CFR 72 rules) while the cask/canister is being loaded in the fuel pool. During transport, the U.S. NRC allows partial credit for fuel burn-up (USNRC ISG-8) under 10 CFR 71 rules thus enabling the high capacity fuel baskets to be used to both store and transport spent nuclear fuel. This condition of reliance on regulatory dispensation is, however, not entirely satisfactory, because the extent of burn-up credit allowed by different regulatory jurisdictions varies widely and the actual amount of burn-up exposure garnered by a fuel assembly is subject to some uncertainty. Evidently, it would be far better to equip the fuel with additional neutron absorption capability such that no reliance on boron credit or burn-up credit is necessary. An improved approach is desired for storing nuclear fuel and controlling reactivity. This disclosure describes a reactivity control device which is intended to be installed to add reactivity mitigation capability to a nuclear fuel assembly while it is stored remotely from the reactor vessel such as in a spent fuel pool and thereafter when transferred to dry storage in a canister. This device may be arbitrarily referred to as “HI-SERT” for convenience of reference and not limitation. Use of the HI-SERT device is intended to require no reliance on boron credit or burn-up credit described above. In one aspect, a reactivity control device for storing nuclear fuel includes: a top tube sheet; an array comprising a plurality of vertically elongated neutron absorber rods fixedly attached to the top tube sheet, the absorber rods arranged parallel to each other; and a floating guide plate slideably mounted on the absorber rods for upward and downward movement along the absorber rods, the floating guide plate movable between a lower position proximate to bottom ends of the absorber rods and an upper position abuttingly engaging the top tube sheet. In one aspect, a reactivity control system for storing nuclear fuel includes: a nuclear fuel assembly comprising a bottom nozzle box, a top nozzle box, a plurality of fuel rods extending vertically between the nozzle boxes, and a plurality of guide tubes extending vertically between the nozzle boxes; a reactivity control device comprising a top tube sheet, a plurality of neutron absorber rods fixedly attached to the top tube sheet, and a floating guide plate slideably mounted on the absorber rods for upward and downward movement along the absorber rods, the absorber rods removably insertable into the guide tubes of the fuel assembly; wherein the reactivity control device has a first uninstalled position prior to insertion of the absorber rods into the fuel assembly in which the floating guide plate is spatially separated from the top tube sheet, and a second installed position after insertion of the absorber rods into the guide tubes of the fuel assembly in which the floating guide plate is abuttingly engaged with the top tube sheet. A method for controlling reactivity in a spent nuclear fuel assembly removed from a nuclear reactor core is provided. The method includes: removing a spent fuel assembly from a nuclear reactor core; positioning a reactivity control device above the spent fuel assembly, the device comprising a top tube sheet, a plurality of absorber rods fixedly attached to the top tube sheet, and a floating guide plate slideably mounted on the absorber rods for upward and downward movement along the absorber rods, the top tube sheet and floating guide plate being spatially separated; aligning each of the absorber rods with a corresponding one of a plurality of guide tubes disposed in the spent fuel assembly; lowering the reactivity control device toward the spent fuel assembly; inserting the absorber rods into the guide tubes; abuttingly engaging firstly the floating guide plate with a top of the fuel assembly; sliding the absorber rods through the floating guide plate while continuing to lower the reactivity control device toward the spent fuel assembly; and abuttingly engaging secondly the top tube sheet with the floating guide plate, wherein the absorber rods are fully inserted in the guide tubes. Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. All drawings are schematic and not necessarily to scale. The features and benefits of the invention are illustrated and described herein by reference to exemplary embodiments. This description of exemplary embodiments is intended to be read in connection with the accompanying drawings, which are to be considered part of the entire written description. Accordingly, the disclosure expressly should not be limited to such exemplary embodiments illustrating some possible non-limiting combination of features that may exist alone or in other combinations of features. In the description of embodiments disclosed herein, any reference to direction or orientation is merely intended for convenience of description and is not intended in any way to limit the scope of the present invention. Relative terms such as “lower,” “upper,” “horizontal,” “vertical,”, “above,” “below,” “up,” “down,” “top” and “bottom” as well as derivative thereof (e.g., “horizontally,” “downwardly,” “upwardly,” etc.) should be construed to refer to the orientation as then described or as shown in the drawing under discussion. These relative terms are for convenience of description only and do not require that the apparatus be constructed or operated in a particular orientation. Terms such as “attached,” “affixed,” “connected,” “coupled,” “interconnected,” and similar refer to a relationship wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise. As used throughout, any ranges disclosed herein are used as shorthand for describing each and every value that is within the range. Any value within the range can be selected as the terminus of the range. In addition, all references cited herein are hereby incorporated by referenced in their entireties. In the event of a conflict in a definition in the present disclosure and that of a cited reference, the present disclosure controls. Referring initially to FIGS. 1-3 and 5, a reactor vessel 25 and a vertically elongated nuclear fuel assembly 20 (also referred to as “fuel bundle” in the art) are shown. In one embodiment, the fuel assembly 20 may be a pressurized water reactor (PWR) fuel assembly. Fuel assembly 20 is removably inserted into the reactor vessel and forms a constituent part of the fuel core 23 for heating the primary coolant circulating therein. In practice, the core comprises an array 116 of such fuel assemblies. Each fuel assembly 20 contains a plurality of fuel rods 21 mechanically coupled together in an array which is insertable and removably as a unit into/from the reactor core 23. Typical fuel assemblies 20 for a pressurized water reactor (PWR) may each hold over 150 fuel rods generally in 10×10 to 17×17 fuel rod grid arrays per assembly. The assemblies may typically be on the order of approximately 14 feet high weighing about 1400-1500 pounds each as an example. The fuel assemblies traditionally have a rectilinear cross-sectional configuration such as a square array as illustrated. Fuel assemblies are further described in commonly assigned U.S. patent application Ser. No. 14/413,807 filed Jul. 9, 2013, which is incorporated herein by reference. The fuel rods 21 are generally cylindrical elongated hollow metal tubular structures formed of materials such as zirconium alloy or stainless steel. The tubes hold a plurality of vertically-stacked cylindrical fuel pellets formed of sintered uranium dioxide and integral burnable poisons arranged in an engineered pattern to facilitate as uniform a burning profile of the fuel as possible (in both axial and cross sectional/transverse directions). The fuel rod tubes may have an external metal cladding formed of corrosion resistant material to prevent degradation of the tube and contamination of the reactor primary coolant water. The opposite ends of the fuel rod are typically sealed. Fuel assembly 20 further generally includes a top nozzle box 22 and bottom nozzle box 24. When mounted in the fuel core 23 inside the reactor vessel shown in FIG. 1, the nozzle boxes allows primary coolant to flow upwards through the fuel assembly 20 between the fuel rods 21 to absorb heat and circulate through the reactor vessel by natural convection. The nozzle boxes 22, 24 have a three-dimensional box-like rectilinear configuration or shape such as a square with squared or perpendicular corners. Referring generally to FIGS. 1-5, multiple longitudinally-extending tubular passageways known as “guide tubes” 36 which are formed within each fuel assembly 20. The guide tubes 36 enable the reactor's control rods 30 to be inserted within the fuel assembly to adjust the power generation rate in the reactor or to provide reactor shut-down. The guide tubes 36 are interspersed throughout the fuel rod matrix in the fuel assembly 20. FIG. 10 shows one example of guide tube penetrations 34 locations in a 17×17 array PWR fuel assembly widely used in the industry. Each control rod comprises a hollow tube filled with neutron absorbing boron carbide pellets. The cavities within each guide tube 36 are accessible to the control rods 30 through the penetrations 34 formed in the recessed floor plate 37 (exposed top face) of the top nozzle box 22 (see FIG. 10). The nuclear fuel assemblies 20 may each include their own individual dedicated control rod assembly that supports a cluster of the reactor's control rods 30, best shown in FIGS. 4 and 5. The control rod assemblies may be referred to as a rod cluster control assembly (RCCA) 31 which is mounted inside the reactor vessel 2 with the nuclear fuel core 23. The RCCAs remain with the reactor vessel as part of the reactor's motorized control rod drive system 32 when swapping out fuel assemblies from the fuel core 23 (i.e. removing spent fuel assemblies and installing fresh fuel assemblies). The RCCA 31 is operably coupled to the control rod drive system 32 and mounted above the fuel assemblies 20 when positioned in the reactor fuel core 23 inside the reactor vessel 25. The drive system 32 generally includes a drive rod 33 operably coupled to a suitable type and capacity motor 42 mounted proximally above the top of the reactor vessel 25 which operates to raise and lower the drive rod and RCCA 31. Drive rod 33 has a lower end grapple or coupling 39 detachably coupled to a drive rod extension 38. The drive rod extension in turn is detachably coupled to the distally located RCCA 31 positioned at the top of the fuel assembly 20 (see, e.g. FIG. 5). During a SCRAM (emergency shutdown procedure of the reactor in which control rods are quickly dropped and inserted into the fuel core to suppress the nuclear reaction), the RCCA 31 is automatically uncoupled from and released from the drive rod extension 38. A drive rod extension support structure 41 (DRESS) positioned between the fuel assembly 20 and drive rod 33 supports and guides the drive rod extension 38 for upward/downward movement. To accommodate multiple fuel assemblies 20 which comprise the core 23, the DRESS 41 is formed by a plurality of tightly packed tubes in which the drive rod extensions 38 travel and structural support members. In practice, each reactor includes a plurality of drive rods, drive rod extensions, and RCCAs 31 to service the multiple fuel assemblies in each fuel core for controlling reactivity. One non-limiting example of such a control rod drive system and related components is described in commonly owned co-pending U.S. patent application Ser. No. 14/417,628 filed Jan. 27, 2015, which is incorporated herein by reference. Each RCCA 31 comprises a control rod support plate 32 to which is mounted the plurality of control rods 30 supported by the plate. The support plate 32 has a specially configured and machined forged central hub 40 which detachably couples to the bottom end coupling mechanism of the drive rod extension 38. The control rods 30 are arranged on the support plate 32 in a pattern which coincides with the geometric layout of the control rod guide tube penetrations 34 and guide tubes 36 formed in the top flow nozzle box 22 (see FIGS. 5 and 10). The foregoing rod cluster control assemblies (RCCA) 31 act to control the nuclear reactivity of the fuel assemblies 20 when loaded in the reactor vessel fuel core 23. However, the RCCA's 31 which support the reactor's control absorber rods 30 remain with the reactor when a spent (exhausted) fuel assembly 20 is eventually removed and temporarily stored in either the water-impounded spent fuel pool 60 (wet storage) within the reactor containment enclosure structure, or thereafter when removed from the pool and loaded into a multi-purpose canister (MPC) for dry transport and/or interim on-site storage of the spent fuel. As discussed in the Background above, the tightly-packed fuel storage cells defined by the fuel baskets in the canisters have limited neutron absorption abilities which alone cannot satisfy the NRC's criticality requirements. In order to extend the duration of the spent fuel assemblies storage time in the fuel pool, neutron absorbing materials may be added to the fuel assemblies. Although reactor control component assemblies 31 (RCCAs) offer a possible solution to control criticality levels in the pool, this approach is not practical from an economic standpoint. A RCCA is a precisely machined steel plate with attached tubes filled with boron carbide pellets. The RCCAs are very expensive components with specially configured forged machined hubs 40 and other appurtenances, which are intended and designed to be used in the reactor core of the reactor vessel to control criticality. This also makes RCCAs impractical for use with spent fuel assemblies transported or stored in multi-purpose canisters to control criticality. To address the criticality issue with storing and transporting spent fuel assemblies in a manner which meets the NRC's sub-criticality criterion without reliance on boron credits, a reactivity control device 100 is disclosed herein. The device is especially adapted and designed for use with spent fuel assemblies held in the reactor's spent fuel pool outside the confines of the reactor vessel 25, and may remain with the fuel assembly when loaded into a multi-purpose canister thereafter. Advantageously, the reactivity control device offers a more economic alternative in terms of capital cost than using the more expensive specialty RCCAs. Reactivity control device 100 (“HI-SERT”) exploits the vacant tubular spaces inside the fuel assembly 20 formed by guide tubes 36 (described above) after the fuel assemblies are removed from the reactor vessel 25. Referring to FIGS. 6-13, reactivity control device 100 comprises an assemblage of parallel vertically elongated neutron absorber rods 110 dimensioned to fit in the guide tubes 36 of the fuel assembly. Absorber rods 110 are cylindrically shaped elements including a fixed top end 111 and opposing free bottom end 112. The bottom ends 112 may be tapered as shown to facilitate insertion into the guide tubes 36 via a lifting tool 152 such as a long-handled tool or a motorized hoist 151 (shown schematically in FIG. 6) often employed with a fuel assembly handling and transport mechanism used with a spent fuel pool. The hoist 151 may be movably mounted to the reactor vessel enclosure structure (e.g. a monorail) or a maneuverable crane. The absorber rods 110 may be comprised of a solid ductile neutron-absorbing material or alternatively a hollow alloy tube (e.g. stainless steel, etc.) in which a neutron absorber material is installed. The neutron absorber material may be comprised of boron, silver, indium, cadmium, and other materials capable of absorbing neutrons. If a tube is used to form the absorber rod, each tube is preferably plugged at both ends to contain the neutron absorber material. However, small holes may be provided at the top and/or bottom of the sealed tubes to extract the moisture from inside the tube (while drying the fuel assembly canister subsequent to fuel loading in the wet spent fuel pool 60 shown in FIG. 14) that would infiltrate the tubes interior during its residence in the fuel pool and to prevent pressure build-up during storage in a dry canister environment. The top ends 111 of the neutron absorber rods 110 are rigidly and immovably connected to a suitably machined top support structure such as fixed top tube sheet 120 which ensures that the absorber rods are supported and precisely align with the locations of the recipient guide tubes 36 in the fuel assembly 20 accessed through penetrations 34 in the floor plate 37 of the top nozzle box 22 (best shown in FIG. 10 depicting some but not all of the penetrations for clarity). Top tube sheet 120 includes a top surface 124, bottom surface 125, and plurality of straight lateral peripheral edges 121 extending between the top and bottom surfaces that forms a perimeter of the tube sheet. Suitably configured flow apertures 122 (e.g. round, etc.) may be formed in tube sheet 120 to allow pool water heated by waste decay heat from the radioactive fuel rods in the fuel assembly 20 to rise and flow upwards from the assembly through the sheet which promotes natural circulation of the water in the spent fuel pool 60, and for drainage when removing the reactivity control device 100 from the fuel assembly in the spend fuel pool 60. Top tube sheet 120 may be substantially rectilinear in top plan view in some embodiments (see FIG. 8). One example of a non-limiting embodiment may include radiused arcuately-shaped or rounded corners 123 formed between adjoining pairs of each of the four peripheral edges 121. The peripheral edges 121 may be substantially straight and arranged orthogonally (i.e. perpendicular) to each other. The rounded corners facilitate insertion of the top tube sheet 120 into an upwardly open top recess 140 formed at the upper end of the top nozzle box 22 of the fuel assembly 20 between the floor plate 37 and top of the box (see, e.g. FIG. 10), as further explained below. Top tube sheet 120 is configured and dimensioned to fit inside the recess 140. The rounded corners 123 may have a relatively large radius such that the corner regions occupy about one-quarter to one-third of the length of each lateral peripheral edge 121 as shown. Other suitable corner configurations such as angled corners comprising a straight linear edge arranged obliquely to the peripheral edges 121 may also be used. In embodiments using solid neutron-absorber rods 110 describe above, the top ends 111 of the rods may be threaded and secured to the top tube sheet 120 via mounting holes 113 in the sheet and threaded nuts 114. In other embodiments using hollow tubular absorber rods 110 described above, the rods may be secured to the top tube sheet 120 by expansion and edge welding in the manner of a typical heat exchanger tube sheet joint. Other suitable methods of joining may be used such as those described in Chapter 7 of the book, “Mechanical Design of Heat Exchangers” By K. P. Singh, et al., (1984) or other forms of robust attachment to fixedly secure the absorber rods 110 to the top tube sheet. A lifting coupling element 150 may be disposed on or in the top tube sheet 120 for handling the reactivity control device 100 via a long-handled gripping tool or hoist; both of which allow plant operating/maintenance personnel to install/remove the reactivity control device from a safe remote location to minimize radiation exposure to the fuel assembly. Any suitable configuration of coupling element 150 may be used which is configured to be detachably engaged by the particular type of lifting tool 152 employed for handling the reactivity control device. Some non-limiting examples of coupling element 150 configurations that may be used include without limitation threaded sockets, quick connect couplings, lifting protrusion with lifting pins or flanges, etc.). In order to facilitate insertion of reactivity control device 100 into the fuel assembly 20 when handling the reactivity control device 100 remotely with a long-handled tool or hoist 151, a lower floating guide plate 130 is provided. Unlike the top tube sheet 120, the guide plate 130 by contrast is slideably mounted on the absorber rods 110 for upward/downward movement thereon. In one embodiment, the guide plate 130 has the same configuration and dimensions as the top tube sheet 120 in top plan view. With continuing reference to FIGS. 6-13, the floating guide plate 130 includes a top surface 134, bottom surface 133, and plurality of straight lateral peripheral edges 135 extending between the top and bottom surfaces that forms a perimeter of the plate. The floating guide plate 130 includes machined rod guide holes 137 which slideably receive the absorber rods 110 therethrough and allow the plate to slide and travel upwards and downwards along a majority of the length of the absorber rods. Preferably, in one embodiment, the guide plate 130 is slideably movable on the absorber rod array between an uninstalled lower position proximate to the bottom ends 112 of the rods 110 (see, e.g. FIGS. 6 and 7) and an installed upper position abuttingly engaging the underside of the top tube sheet 120 (see, e.g. FIG. 13). The locations of the floating guide plate holes 137 precisely correspond to the fuel assembly's guide tubes 36 and corresponding guide tube penetrations 34 layout/pattern in fuel assembly's upper end structure (e.g. top nozzle box). This vertically aligns each of the absorber rods 110 with a mating one of the fuel assembly's guide tubes 36 for insertion therein. Accordingly, in plan view, the pattern of the absorber rod 110 array (see, e.g. FIG. 9) is preferably identical to the pattern of the guide tubes 36 and penetrations 34 in the fuel assembly 20. To prevent the floating guide plate 130 from sliding off the absorber rod array, the guide plate is captured proximate to the bottom ends 112 of the rods by one or more end stops 138 formed on the lower extremity of the absorber rod array on reactivity control device 100. The end stops 138 are preferably disposed on the absorber rod array proximate to but spaced vertically a short distance above the bottom ends 112 of the absorber rods so that the rods extend and protrude downwards below the guide plate 130 as shown. This allows the bottom ends 112 of the absorber rods to be inserted through the guide tube penetrations 36 in the top nozzle box 22 of the fuel assembly 20 without interference from the guide plate. Preferably, the height and location of the end stops is selected close enough to the bottom of the absorber rod array to prevent excessive radial inward/outward splaying or displacement of the free bottom ends 112 of the absorber rods 110 which might otherwise interfere with the precise alignment of the rod ends with their corresponding guide tube penetration 34 in the fuel assembly top nozzle box 22 necessary for insertion into the fuel assembly guide tubes 36. Accordingly, the floating guide plate 130 serves an important function of maintaining the absorber rod 110 pattern (see, e.g. bottom plan view of FIG. 9) at the bottom of the rod array distally from the top tube sheet 120 that supports the plate. This ensures to precise alignment of the absorber rods 110 with the plurality of guide tube penetrations in the floor plate 37 of the top nozzle box 22. The end stops 138 may be formed and configured in various ways to retain the guide plate 130 on the array of absorber rods 110. In one embodiment shown in FIG. 7, the end stops 138 may be formed by a necked down or reduced diameter upper portion 143 formed preferably on at least two or more outboard absorber rods 110 at diametrically opposite sides of the absorber rod array (e.g. near corners 136 in one non-limiting example). The diameter of the mating rod guide holes 137 for the end stop absorber rods 110 with reduced diameter upper portion 143 is correspondingly smaller than the guide holes which slideably receive the remaining full diameter absorber rods 110 in the array. The end stop absorber rods 110 have a full diameter lower portion 142 extending from the reduced diameter upper portion 143 below the floating guide plate 130 towards the bottom ends 112 of the rods (except for tapered rod ends if provided). The transition between the reduced diameter upper portion 143 of each end stop absorber rods 110 and full diameter lower portion 142 define a stepped shoulder 139 that engages and captures the guide plate 130, thereby defining the end stop 138 that retains the plate on the absorber rod array (see FIG. 7 enlarged cross sectional detail). The smaller mounting hole 137 for the end stop absorber rods 110 has a diameter smaller than the outside diameter of the full diameter absorber rods to capture the floating guide plate 130. Preferably, the reduced diameter portion 143 of the end stop absorber rods 110 extends upwards for sufficient distance on each rod so that the floating guide plate 130 may form an abutting relationship with the top tube sheet 120, for reasons explained below. In other embodiments, the end stops 138 may be formed by radial protrusions extending outwards from preferably at least two absorber rods 110 at the same location described above for end stops defined by the stepped shoulder 143 on the rods. The protrusions have a length that extends for a distance beyond the diameter of the rod guide holes 137 in the floating guide plate 130 to capture the plate on the end stop absorber rods. Other possible ways of forming end stops on the absorber rods 110 are possible. As noted above, guide plate 130 may have the same shape and dimensions as top tube sheet 120 and is therefore substantially rectilinear in top plan view (see, e.g. FIG. 9). In some embodiments, the guide plate 130 may also include the same radiused arcuately-shaped rounded corners 136 formed between each of the four peripheral edges 135 which may be substantially straight. The rounded corners 123 may have a relatively large radius such that the corner regions occupy about one-quarter to one-third of the length of each peripheral edge 121 as shown. Other corner configurations such as angled or squared corners may be used. The radiused corners 136 ensure that that the absorber rods 110 are orientated and properly vertically aligned top nozzle box 22 for insertion into the guide tube penetrations formed in the nozzle box. The floating guide plate 130 has a complementary configuration to the upwardly open top recess 140 in the fuel assembly top nozzle box 22 (in top plan view) to therefore facilitate insertion with the proper orientation. Accordingly, in the illustrated embodiment, the guide plate 130 may only be inserted into the nozzle box top recess 140 when the peripheral edges 135 of the plate are oriented parallel to the four orthogonal straight lateral sidewalls 141 circumscribing the nozzle box floor plate 37. This locates the corners 136 of the guide plate in vertical alignment with truncated corner regions 144 of the top nozzle box 22 formed between each adjacent pair of sidewalls 141 (the same rationale applies to the rounded corners 123 of the top tube sheet 120 describe above). In one non-limiting embodiment, the truncated corner regions 144 of the top nozzle box 22 may be formed by inward facing angled inner corner surfaces 145 circumscribing and formed adjacent to the nozzle box top recess 140. The inner corner surfaces 145 may be flat and vertically oriented. Each angled inner corner surface 145 is oriented obliquely to the pair of adjacent straight sidewalls 141 of the top nozzle box 22 which meet at each of the corner regions. In one non-limiting embodiment illustrated, angled corner surfaces 145 may be formed on upwardly extending guide protrusions 146 formed on the top nozzle box 22 (e.g. on sidewalls 141) at each of the truncated corner regions 144. As best shown in FIGS. 8 and 13, the guide protrusions 146 extend diagonally across the sidewalls 141 in the corners of the nozzle box top recess 140 to create an effective upwardly open surface area in top plan view for receiving the top tube sheet 120 and floating guide plate 130 which is less than the actual surface area of the floor plate 37 of the top nozzle box 22 beneath the protrusions. This restricts insertion of the top tube sheet and guide plate into the nozzle box top recess 140 to a single rotational orientation of the sheet and plate with respect to the top recess. In operation, if the corners 137 of the guide plate 130 are not vertically aligned with the truncated corner regions 144 of the top nozzle box 22, the corners 137 would catch on (i.e. engage) the tops of the sidewalls 141 or guide protrusions 146 if provided, thereby preventing full insertion of the floating guide plate 130 into the recess 140. This ensures that each of the neutron absorber rods 110 are properly aligned vertically with a corresponding guide tube penetration 34 in the nozzle floor plate 37 when the rods and guide plate 130 are being lowered into mutual engagement with the fuel assembly 20 (i.e. top nozzle box 22). Because the reactivity control device 100 is typically suspended via cables or chain from a remote hoist 151 when being inserted or withdrawn from a fuel assembly 20 submerged 25 feet or more in the water-impounded spent fuel pool 60 in a fuel storage rack 70 (see, e.g. FIGS. 14-15) or multi-purpose canister 80 in the fuel pool (see, e.g. FIGS. 16-17), the ability to easily achieve proper rotational orientation of the reactivity control device about its vertical centerline Cv with respect to the fuel assembly and its top nozzle box 22 is significant benefit when using this type of rigging arrangement. The top tube sheet 120 is rotationally oriented in the same radial position with respect to vertical centerline Cv as the lower floating guide plate 130 so have the corners 123 of the tube sheet are positioned vertically above corners 136 of the guide plate producing an identical footprint in top plan view for the same foregoing reasons. In other possible embodiments, the truncated corner regions 144 of the fuel assembly top nozzle box 22 may have arcuately radiused or rounded inner corner surfaces 145 of similar shape to the corners 136 and 123 of the floating guide plate 130 and top tube sheet 120 instead of being obliquely angled in the illustrated embodiment. Other possible complementary and mating polygonal shape combinations (in top plan view) of the floating guide plate 130 (and top tube sheet 120) and top recess 140 of the top nozzle box 22 may be used (e.g. hexagonal, octagonal, triangular, etc.) so long as the combination of shapes selected permits insertion of the plate 130 into the top recess in one proper orientation. Preferably, the combination of shapes selected are non-circular unless other provisions are made to ensure that guide plate 130 and top tube sheet 120 can be inserted into the top nozzle box top recess 140 in a single orientation (e.g. mating radial protrusions on the plate/sheet and recesses in the top nozzle box, etc.). The floating guide plate 130 may also include a plurality of suitably configured flow apertures 131 (e.g. round, etc.) similar to flow apertures 122 formed in the top tube sheet 120. Preferably, the flow apertures 131 and 122 are arranged in the same layout or pattern so that each flow aperture 131 is concentrically aligned with a mating flow aperture 122 when the guide plate 130 and top tube sheet 120 are abuttingly engaged when the reactivity control device 100 is fully inserted and positioned in the fuel assembly 20 when the floating guide plate is in the upper installed position. This ensures that water in the spent fuel pool 60 heated by the waste decay heat by the fuel rods in the fuel assembly 20 can flow through each pair of apertures 122, 132 in the tightly stacked top tube sheet and floating guide plate for cooling the fuel assembly. In one embodiment, therefore, the flow apertures 122 and 131 may each have the same diameter to provide unrestricted flow through the sheet and plate. In one non-limiting construction, as an example, the materials selected for the upper structure of the fuel assembly 20 (i.e. top nozzle box 22) and guide tubes 36 in the fuel assembly may be an austenitic stainless steels (e.g., type 304, 304L, 304LN, 316, 316L, 316 LN) or a nickel alloy (e.g., Hastelloy, etc. widely used in the nuclear industry). The neutron absorber material for selected for absorber rods 110 may be a powdered or metal matrix composite containing boron carbide or elemental boron. Borated stainless steel has the advantage of being directly weldable to the top structure (thus dispensing with the sheathing tube), but its boron loading capacity is quite modest, making it a relatively weak neutron absorber. The floating guide plate 130, top tube sheet 120, and coupling element 150 may be made of similar materials as the fuel assembly top nozzle box and guide tubes, or a different material. Other materials than those examples given herein may be used. In one non-limiting example of a reactivity control device 100 designed for use in a typical 17×17 PWR fuel assembly 20, the device may have a height of approximately 13.8 feet (4.2 meters) and width (of top tube sheet 120/floating guide plate 130) of approximately 6.5 inches (16.5 cm). The absorber rods 110 may have an outside diameter of approximately 0.3125 inches (8 mm). For comparison, the 17×17 fuel assembly has a height of approximately 14 feet (4.3 meters) and width of approximately 8.3 inches (21 cm). The guide tubes 36 have an outside diameter of approximately 1.2 inches (3.1 cm). These dimensions are representative, but not limiting. Reactivity control device 100 is advantageously a mechanically simple, economically fabricated, and reusable device. As such, it can be used to improve the sub-criticality of the fuel while being stored in a spent fuel pool (wet storage). Once equipped with a reactivity control device 100, the reactivity of the fuel in the fuel assembly is permanently decreased making it suitable for transfer to dry storage (under 10 CFR 72 rules) and transport (under 10 CFR 71 rules) without reliance on burn-up or boron credit. Because the fuel assembly is extremely radioactive, the installation of reactivity control device preferably occurs in a fuel pool or in a hot cell by remote means. The description provided herein of the reactivity control device assumes for convenience of description and not limitation installation into a fuel assembly placed in a spent fuel pool rather than hot cell. A non-limiting example of a method or process for controlling reactivity in a nuclear fuel assembly removed from a fuel core of a nuclear reactor will now be described. The reactivity is controlled in one embodiment using the reactivity control device 100 which may be deployed and installed using a remote handling device such as a long-handled tool or crane/hoist. FIGS. 10-13 show sequential steps in the installation process for the reactivity control device. The fuel assembly 20 may initially be installed in the fuel core 23 of the nuclear reactor vessel 25 and used to power the heating of the primary coolant. The rod cluster control assembly (RCCA) 31 inside the reactor vessel 25 is removably inserted in the fuel assembly 20 and used to control the reactivity in a known manner. After the nuclear fuel source (i.e. uranium) has been depleted, the fuel assembly requires removal from the reactor vessel and replacement (“spent fuel assembly”). The replacement includes among other things opening the reactor vessel and removing the RCCA 31 from the fuel core. The spent fuel assembly 20 is then removed from reactor vessel 25, transported, and placed in the spent fuel pool 60 to submerge the fuel assembly (see, e.g. FIGS. 14 and 15). In one embodiment, the fuel assembly 20 may be transported to and loaded into a vacant cell 71 of a fuel storage rack 70 positioned on the bottom 64 of the pool which holds a plurality of fuel assemblies 20. A new fuel assembly 20 may be inserted into the fuel core, the same RCCA 31 (which remains with the reactor vessel) is then re-inserted into the new fuel assembly, and the reactor vessel 25 is closed. It will be appreciated that numerous other disassembly and reassembly steps are involved as known to those skilled in the art, which are omitted herein for brevity. Referring to FIG. 10, with the fuel assembly 20 placed in the spent fuel pool 60, the reactivity control device 100 is ready to be installed. The reactivity control device is first coupled to a lifting tool 152 (e.g. long-handled tool or hoist 151) via coupling element 150 mounted on the top tube sheet 120 and raised. The reactivity control device 100 is in an upright vertical position (FIGS. 6-13) wherein the tube sheet 120 and guide plate 130 are oriented horizontally and the absorber rods 110 are oriented vertically perpendicular to the tube sheet and guide plate as shown. The top tube sheet 120 and floating guide plate 130 are spatially separated. The guide plate 130 is initially now is in the lower position proximate to the bottom ends 112 of the absorber rods 110 (see, e.g. FIGS. 6 and 7). The installation process continues by positioning the reactivity control device 100 above the fuel assembly 20 (e.g. with hoist 151), and then lowering the reactivity control device towards the fuel assembly. The free bottom ends 112 of the absorber rods 110 first enter the top recess 140 of the top nozzle box 22 between the sidewalls 141. The absorber rods 110 are therefore partially inserted into the nozzle box of the fuel assembly 20 at this point. Once the bottom ends of the rods are captured in the recess 140 between the sidewalls 141 that extend upwards from the fuel assembly 20, it bears noting lateral movement of the absorber rod array without raising the reactivity control device 100 prevents the device from laterally wandering and moving beyond the confines of the fuel assembly which facilitate installation. The installation process continues by angularly rotating the reactivity control device 100 about its centerline Cv until the corners 136 of the of the floating guide plate 130 are vertically aligned with the truncated corner regions 144 of the fuel assembly top nozzle box 22 and the straight peripheral edges 135 are oriented parallel to the sidewalls 141 of the fuel assembly top nozzle box 22. The floating guide plate 130 next engages the top nozzle box 22. If the desired vertical alignment is already achieved when lowering the reactivity control device 100 towards the fuel assembly 20, this step may be omitted. This alignment process is necessary to ensure each absorber rod 110 is properly positioned above and vertically aligned with a corresponding guide tube 36 in the fuel assembly. With the proper vertical alignment achieved in either case, the reactivity control device 100 is lowered farther to insert the free bottom ends 112 of the absorber rods 112 into one of the guide tube penetrations 34 in the top nozzle box 22 as shown in FIG. 11. It bears noting that if the absorber rods 110 and guide tube penetrations 34 are not properly aligned first, the bottom ends 112 will abutting engage the top floor plate 37 of the nozzle box, thereby preventing the reactivity control device 100 from being lowered any farther. The reactivity control device 100 is then continues to be lowered still farther until the floating guide plate 130 abuttingly engages the top of the fuel assembly 20 (i.e. floor plate 37 of the top flow box 22). This is shown in FIG. 12. The guide plate 130 is nested and positioned completely within the top recess 140 of the fuel assembly and below the top edges of the sidewalls 141 and guide protrusions 146. The guide plate 130 remains stationary in this position during the remainder of the reactivity control device installation process. The installation process proceeds by continuing to lower the reactivity control device 100 farther until the top tube sheet 120 next abuttingly engages or contacts the floating guide plate 130 within the top recess 140 of the top nozzle box 22), as shown in FIG. 13. This indicates that the reactivity control device 100 is fully installed and inserted into the fuel assembly 20 wherein the array of absorber rods 110 are correspondingly fully inserted into the fuel assembly guide tubes 36. As this occurs, the floating guide plate 130 remains in contact with the fuel assembly's top nozzle box 22 allowing the absorber rods 110 to slide and pass through the floating guide plate within guide holes 137 until the top tube sheet engages the floating guide plate. The top tube sheet 120 may also be nested and positioned completely within the top recess 140 of the fuel assembly 20 and below the top edges of the sidewalls 141 and guide protrusions 146. Advantageously, the reactivity control device 100 nests in the fuel assembly's top nozzle box 22 in a recessed manner described above so that the fuel assembly can be handled by existing fuel assembly handling equipment (e.g. handling tools or hoists) without interference. A portion of the coupling element 150 may protrude above the top nozzle box in some embodiments to facilitate recoupling to the lifting tool 152. In other embodiments, the coupling element 150 may not extend above the top edges of the sidewalls 141 of the fuel assembly 20 and/or the guide protrusions 146. The handling tool 152 may now be uncoupled or disconnected from the coupling element 150 of the reactivity control device 100. If the reactivity control device 100 is to be removed from the fuel assembly 20 for some reason, the floating guide plate 130 will slide down along the absorber rods 110 as the top tube sheet 120 disengages and spatially separates from the guide plate as the device is raised. The guide plate 130 continues to slide down along the absorber rod array until it comes in contact with the end stops 138 on the rods (see, e.g. FIG. 7). The reactivity control device 100 is lifted completely out of the fuel assembly while advantageously maintaining all of the absorber rods 110 in the correct orientation and pattern for reinstallation into another fuel assembly. It is evident from the foregoing that the multiple reactivity control assemblies 100 can be utilized in parallel each covering all of the guide tubes 36 of each spent fuel assembly 20. Although it may be possible to install individual single absorber rods into each guide tube, this approach is not practical because of the difficulty of installation encountered if attempting to insert a rod (solid or tubular) remotely some 25 feet underwater in the spent fuel pool 60. This tantamount to threading a needle from a remote location. By contrast, a single reactivity control device 100 having multiple absorber rods 110, however, is advantageously far more operator-friendly and less time intensive with the added benefit of providing far better visual verification of presence of a rod in each guide tube of the fuel assembly. FIGS. 14 and 15 depict a spent fool pool 60 such as the type which may be used to temporarily store spent fuel assembles 20. The pool includes a plurality of vertical sidewalls 61 and adjoining bottom floor 64 which define a cavity 62 that holds water W for submerging the fuel assemblies. One or more submerged fuel storage racks 70 rest on the bottom floor 62 which are configured to hold a plurality of fuel assemblies 20. Each rack generally comprises a grid array of closely packed open compartments or cells 71 defined by a plurality of adjacent tightly packed and parallel elongated tubes 72 having a height H sufficient to hold a fuel assembly. The tubes have open tops 73 providing access to the cells 71 which are configured and dimensioned for inserting and storing a single fuel assembly 20 in each. Each cell 71 may include bottom openings (not shown) which allows water W to infiltrate and circulate around each fuel assembly to remote waste decay heat generated by the fuel rods therein. The fuel assemblies 20 in the storage rack 70 may each include a reactivity control device 100 disposed therein as described herein. Fuel storage racks are further described in commonly assigned U.S. patent application Ser. No. 14/367,705 filed Jun. 20, 2014, which is incorporated herein by reference. The fuel assemblies 20 with inserted reactivity control device 100 may be transferred to and stored a multi-purpose canister 80, a non-limiting example of which is shown in FIGS. 16 and 17. Canister 80 generally comprises a cylindrical shell, baseplate 85, and sealable/weldable lid 81 which form the confinement boundary for the stored fuel assemblies. The confinement boundary may be a seal-welded enclosure of all stainless steel construction. The canister includes a fuel basket 86 which has composite cell structure having a rectilinear honeycomb construction formed by a plurality of tightly packed elongated tubes 82 forming open top elongated cells 83 each configured and dimensioned to hold a single fuel assembly 20. The fuel assemblies 20 may be transferred from the fuel storage rack 70 to the canister 80 underwater while submerged in the spent fuel pool 60 to minimize radiation levels. Multi-purpose canisters are further described in commonly assigned U.S. Pat. Nos. 7,096,600 and 5,898,747, which are incorporated herein by reference. When loaded, the multi-purpose canisters 80 may be removed from the spent fuel pool 60, dried using inert gases and vacuum in a manner known in the art, and transferred to an outer transport or storage 84 with a sealable lid 85 (e.g. “overpack”). While the foregoing description and drawings represent some example systems, it will be understood that various additions, modifications and substitutions may be made therein without departing from the spirit and scope and range of equivalents of the accompanying claims. In particular, it will be clear to those skilled in the art that the present invention may be embodied in other forms, structures, arrangements, proportions, sizes, and with other elements, materials, and components, without departing from the spirit or essential characteristics thereof. In addition, numerous variations in the methods/processes described herein may be made. One skilled in the art will further appreciate that the invention may be used with many modifications of structure, arrangement, proportions, sizes, materials, and components and otherwise, used in the practice of the invention, which are particularly adapted to specific environments and operative requirements without departing from the principles of the present invention. The presently disclosed embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being defined by the appended claims and equivalents thereof, and not limited to the foregoing description or embodiments. Rather, the appended claims should be construed broadly, to include other variants and embodiments of the invention, which may be made by those skilled in the art without departing from the scope and range of equivalents of the invention. |
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description | This present application is a continuation of U.S. National Phase PCT/IB2012/002714 filed Dec. 13, 2012, which claims priority from Japanese Application No. 2012-014248 filed Jan. 26, 2012, and Japanese Patent Application No. 2012-228764 filed Oct. 16, 2012, the entire disclosure of which is incorporated herein by reference for all purposes. 1. Technical Field The present disclosure relates to apparatuses for generating extreme ultraviolet (EUV) light. 2. Related Art In recent years, semiconductor production processes have become capable of producing semiconductor devices with increasingly fine feature sizes, as photolithography has been making rapid progress toward finer fabrication. In the next generation of semiconductor production processes, microfabrication with feature sizes at 60 nm to 45 nm, and further, microfabrication with feature sizes of 32 nm or less will be required. In order to meet the demand for microfabrication with feature sizes of 32 nm or less, for example, an exposure apparatus is needed in which a system for generating EUV light at a wavelength of approximately 13 nm is combined with a reduced projection reflective optical system. Three kinds of systems for generating EUV light are known in general, which include a Laser Produced Plasma (LPP) type system in which plasma is generated by irradiating a target material with a laser beam, a Discharge Produced Plasma (DPP) type system in which plasma is generated by electric discharge, and a Synchrotron Radiation (SR) type system in which orbital radiation is used to generate plasma. An apparatus according to one aspect of the present disclosure for generating extreme ultraviolet light may include a reference member, a chamber fixed to the reference member, the chamber including at least one window, a laser beam introduction optical system configured to introduce an externally supplied laser beam into the chamber through the at least one window, and a positioning mechanism configured to position the laser beam introduction optical system to the reference member. Hereinafter, selected embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The embodiments to be described below are merely illustrative in nature and do not limit the scope of the present disclosure. Further, the configuration(s) and operation(s) described in each embodiment are not all essential in implementing the present disclosure. Note that like elements are referenced by like reference numerals and characters, and duplicate descriptions thereof will be omitted herein. 1. Overview 2. Overview of EUV Light Generation System 2.1 Configuration 2.2 Operation 3. EUV Light Generation System in which Laser Beam Introduction Optical System Is Positioned: First Embodiment 3.1 Configuration 3.2 Operation 4. Examples of Positioning Mechanism 4.1 Second Embodiment 4.2 Third Embodiment 4.3 Fourth Embodiment 5. Examples of Optical Elements 5.1 Fifth Embodiment 5.2 Sixth Embodiment 6. Examples of Moving Mechanism 6.1 Seventh Embodiment 6.2 Eighth Embodiment 6.3 Ninth Embodiment 6.4 Tenth Embodiment 6.5 Eleventh Embodiment 7. EUV Light Generation System Including Pre-pulse Laser Apparatus: Twelfth Embodiment 7.1 Configuration and Operation 7.1 Details of Laser Beam Measuring Unit 8. EUV Light Generation Apparatus in which Laser Beam Introduction Optical System Is Housed in Box: Thirteenth Embodiment In an LPP-type EUV light generation system, a target material may be irradiated with a laser beam outputted from a laser apparatus. Upon being irradiated with the laser beam, the target material may be turned into plasma, and light including EUV light may be emitted from the plasma. The emitted EUV light may be collected by an EUV collector mirror provided in the chamber and supplied to an external apparatus such as an exposure apparatus. A laser beam introduction optical system for introducing the laser beam into the chamber may preferably be positioned with high precision. If the laser beam introduction optical system is not positioned with high precision, a target material may not be irradiated with the laser beam, and an output of EUV light may become unstable. Further, a target material may preferably be irradiated with the laser beam at a predetermined position inside the chamber which coincides with a focus of the EUV collector mirror, so that the emitted EUV light is supplied to the exposure apparatus constantly at a desired angle. According to one or more embodiments of the present disclosure, an EUV collector mirror and a laser beam introduction optical system may be fixed to a reference member such that respective focuses of the EUV collector mirror and the laser beam introduction optical system coincide with each other. Accordingly, the EUV collector mirror and the laser beam introduction optical system may be positioned to each other with high precision. FIG. 1 schematically illustrates an exemplary configuration of an LPP type EUV light generation system. An EUV light generation apparatus 1 may be used with at least one laser apparatus 3. Hereinafter, a system that includes the EUV light generation apparatus 1 and the laser apparatus 3 may be referred to as an EUV light generation system 11. As shown in FIG. 1 and described in detail below, the EUV light generation system 11 may include a chamber 2 and a target supply device 26. The chamber 2 may be sealed airtight. The target supply device 26 may be mounted onto the chamber 2, for example, to penetrate a wall of the chamber 2. A target material to be supplied by the target supply device 26 may include, but is not limited to, tin, terbium, gadolinium, lithium, xenon, or any combination thereof. The chamber 2 may have at least one through-hole or opening formed in its wall, and a pulse laser beam 32 may travel through the through-hole/opening into the chamber 2. Alternatively, the chamber 2 may have a window 21, through which the pulse laser beam 32 may travel into the chamber 2. An EUV collector mirror 23 having a spheroidal surface may, for example, be provided in the chamber 2. The EUV collector mirror 23 may have a multi-layered reflective film formed on the spheroidal surface thereof. The reflective film may include a molybdenum layer and a silicon layer, which are alternately laminated. The EUV collector mirror 23 may have a first focus and a second focus, and may be positioned such that the first focus lies in a plasma generation region 25 and the second focus lies in an intermediate focus (IF) region 292 defined by the specifications of an external apparatus, such as an exposure apparatus 6. The EUV collector mirror 23 may have a through-hole 24 formed at the center thereof so that a pulse laser beam 33 may travel through the through-hole 24 toward the plasma generation region 25. The EUV light generation system 11 may further include an EUV light generation controller 5 and a target sensor 4. The target sensor 4 may have an imaging function and detect at least one of the presence, trajectory, position, and speed of a target 27. Further, the EUV light generation system 11 may include a connection part 29 for allowing the interior of the chamber 2 to be in communication with the interior of the exposure apparatus 6. A wall 291 having an aperture may be provided in the connection part 29. The wall 291 may be positioned such that the second focus of the EUV collector mirror 23 lies in the aperture formed in the wall 291. The EUV light generation system 11 may also include a laser beam direction control unit 34, a laser beam focusing mirror 22, and a target collector 28 for collecting targets 27. The laser beam direction control unit 34 may include an optical element (not separately shown) for defining the direction into which the pulse laser beam 32 travels and an actuator (not separately shown) for adjusting the position and the orientation or posture of the optical element. With continued reference to FIG. 1, a pulse laser beam 31 outputted from the laser apparatus 3 may pass through the laser beam direction control unit 34 and be outputted therefrom as the pulse laser beam 32 after having its direction optionally adjusted. The pulse laser beam 32 may travel through the window 21 and enter the chamber 2. The pulse laser beam 32 may travel inside the chamber 2 along at least one beam path from the laser apparatus 3, be reflected by the laser beam focusing mirror 22, and strike at least one target 27 as a pulse laser beam 33. The target supply device 26 may be configured to output the target(s) 27 toward the plasma generation region 25 in the chamber 2. The target 27 may be irradiated with at least one pulse of the pulse laser beam 33. Upon being irradiated with the pulse laser beam 33, the target 27 may be turned into plasma, and rays of light 251 including EUV light may be emitted from the plasma. At least the EUV light included in the light 251 may be reflected selectively by the EUV collector mirror 23. EUV light 252, which is the light reflected by the EUV collector mirror 23, may travel through the intermediate focus region 292 and be outputted to the exposure apparatus 6. Here, the target 27 may be irradiated with multiple pulses included in the pulse laser beam 33. The EUV light generation controller 5 may be configured to integrally control the EUV light generation system 11. The EUV light generation controller 5 may be configured to process image data of the target 27 captured by the target sensor 4. Further, the EUV light generation controller 5 may be configured to control at least one of: the timing when the target 27 is outputted and the direction into which the target 27 is outputted. Furthermore, the EUV light generation controller 5 may be configured to control at least one of: the timing when the laser apparatus 3 oscillates, the direction in which the pulse laser beam 31 travels, and the position at which the pulse laser beam 33 is focused. It will be appreciated that the various controls mentioned above are merely examples, and other controls may be added as necessary. FIG. 2A is a plan view illustrating an EUV light generation apparatus according to a first embodiment of the present disclosure connected to an exposure apparatus. FIG. 2B is a sectional view of the EUV light generation apparatus and the exposure apparatus shown in FIG. 2A, taken along IIB-IIB plane. As shown in FIGS. 2A and 2B, an EUV light generation apparatus 1 may include an installation mechanism 7, a reference member 9, and a chamber 2. A surface of a floor shown in FIG. 2B may serve as a mechanical reference plane on which the EUV light generation apparatus 1 and an exposure apparatus 6 are installed. The reference member 9 may be supported by the installation mechanism 7 installed on the floor serving as the mechanical reference plane. The installation mechanism 7 may include a mechanism (not separately shown) to move the reference member 9 relative to the installation mechanism 7, and the reference member 9 and the chamber 2 may be movable relative to the exposure apparatus 6 through the aforementioned mechanism included in the installation mechanism 7. The installation mechanism 7 may also include another mechanism (not separately shown) to position the reference member 9 relative to the exposure apparatus 6. Through these mechanisms, the reference member 9 may first be positioned relative to the exposure apparatus 6. The reference member 9 may have a flow channel (not separately shown) formed therein, through which a heat carrier may flow to retain the temperature of the reference member 9 substantially constant. The chamber 2 may be substantially cylindrical in shape. The chamber 2 may be mounted to the reference member 9 such that one end in the axial direction of the chamber 2 is covered by the reference member 9 (see FIG. 2B). For example, a sloped surface may be formed on the reference member 9, and the chamber 2 may be fixed to the sloped surface of the reference member 9 so that the other end of the chamber 2 faces the exposure apparatus at a predetermined angle. A connection part 29 may be connected to the other end of the chamber 2 to connect the chamber 2 to the exposure apparatus 6. As discussed, the target supply device 26 (see FIG. 1) may be fixed to the chamber 2 to supply targets to the plasma generation region 25 in the chamber 2. The EUV collector mirror 23 may be fixed to the reference member 9 through an EUV collector mirror mount 23a. The EUV collector mirror 23 may be fixed to the reference member 9 such that the first focus of the EUV collector mirror 23 lies in the plasma generation region 25 and the second focus thereof coincides with the intermediate focus 292 specified by the exposure apparatus 6. Since the reference member 9 is positioned relative to the exposure apparatus 6 and fixed through a stopper (not separately shown), a variation in the position and/or posture of the EUV collector mirror 23, which is fixed to the reference member 9, relative to the exposure apparatus 6 may be suppressed. A housing chamber 9a that is in communication with the chamber 2 through a through-hole and a housing chamber 9b adjacent to the housing chamber 9a may be formed in the reference member 9. A window 38 may be provided between the housing chamber 9a and the housing chamber 9b. Thus, the interior of the chamber 2 and the housing chamber 9a may be kept at a low pressure. A lid 9c may be operably provided in the housing chamber 9b to seal the housing chamber 9b. A laser beam focusing optical system 60 that includes a high-reflection mirror 61 and a laser beam focusing mirror 62 may be provided in the housing chamber 9a. The laser beam focusing mirror 62 may be an off-axis paraboloidal mirror. A laser beam introduction optical system 50 that includes a beam splitter 52 and a high-reflection mirror 53 may be provided in the housing chamber 9b. A laser beam measuring unit 37 may further be provided in the housing chamber 9b. The high-reflection mirror 61 and the laser beam focusing mirror 62 may be fixed to the reference member 9 through respective holders. The high-reflection mirror 61 and the laser beam focusing mirror 62 may be positioned such that a laser beam incident on the high-reflection mirror 61 is reflected thereby toward the laser beam focusing mirror 62 at a predetermined angle and the laser beam from the high-reflection mirror 61 is reflected by the laser beam focusing mirror 62 to be focused in the plasma generation region 25, where the first focus of the EUV collector mirror 23 lies. In this way, the laser beam focusing optical system 60 and the EUV collector mirror 23 may be fixed to the reference member 9 in the above-described positional relationship, and the reference member 9 may then be positioned to the exposure apparatus 6. Accordingly, EUV light emitted in the plasma generation region 25 may stably be supplied to the exposure apparatus 6 at a desired angle. The beam splitter 52 and the high-reflection mirror 53 may also be fixed to the reference member 9. The beam splitter 52 and the high-reflection mirror 53 may be positioned such that a laser beam that has entered the housing chamber 9b is first incident on the beam splitter 52 and the laser beam reflected by the beam splitter 52 is incident on the high-reflection mirror 53 at a predetermined angle. This predetermined angle may be set such that the laser beam reflected by the high-reflection mirror 53 is incident on the high-reflection mirror 61 provided inside the housing chamber 9a. In this way, the laser beam introduction optical system 50 may be fixed to the reference member 9 and positioned relative to the laser beam focusing optical system 60, and thus a variation in the position and/or the posture of the laser beam introduction optical system 50 relative to the laser beam focusing optical system 60 may be suppressed. Accordingly, the position and/or the angle at which the laser beam enters the laser beam focusing optical system 60 may be set precisely. In addition, the laser beam measuring unit 37 may be fixed to the reference member 9. The laser beam measuring unit 37 may be positioned such that the laser beam transmitted through the beam splitter 52 enters the laser beam measuring unit 37. In this way, the laser beam measuring unit 37 may be fixed to the reference member 9 and positioned relative to the laser beam introduction optical system 50, and thus a variation in the position and/or the posture of the laser beam measuring unit 37 relative to the laser beam introduction optical system 50 may be suppressed. Accordingly, a beam intensity profile, pointing, and divergence of a laser beam that enters the laser beam measuring unit 37 from the laser beam introduction optical system 50 may constantly be measured with high precision. The beam splitter 52, the high-reflection mirror 53, and the laser beam measuring unit 37 may be positioned and fixed to the reference member 9 through a positioning mechanism 10. The positioning mechanism 10 may serve to position optical elements such as the beam splitter 52 to the reference member 9, and the configuration thereof is not particularly limited to those described in the subsequent embodiments. An optical pipe 66 may be attached to the reference member 9 through a flexible pipe 68. High-reflection mirrors 671 and 672 may be provided in the optical pipe 66. The optical pipe 66 may also be connected to a laser apparatus 3. The exposure apparatus 6 may include a plurality of high-reflection mirrors 6a through 6d. A mask table MT and a workpiece table WT may be provided in the exposure apparatus 6. In the exposure apparatus 6, a mask on the mask table MT may be irradiated with EUV light to project an image on the mask onto a workpiece such as a semiconductor wafer on the workpiece table WT. By transitionally moving the mask table MT and the workpiece table WT simultaneously, the pattern on the mask may be transferred onto the workpiece. A laser beam outputted from the laser apparatus 3 may be reflected sequentially by the high-reflection mirrors 671 and 672 to enter the housing chamber 9b of the reference member 9. The laser beam that has entered the housing chamber 9b may be incident on the beam splitter 52. The beam splitter 52 may be positioned to reflect the laser beam incident thereon with high reflectance toward the high-reflection mirror 53 and transmit a part of the laser beam toward the laser beam measuring unit 37. The high-reflection mirror 53 may reflect the laser beam from the beam splitter 52 to guide the laser beam into the housing chamber 9a through the window 38. The laser beam that has entered the housing chamber 9a may be incident on the high-reflection mirror 61. The high-reflection mirror 61 may be positioned to reflect the laser beam incident thereon toward the laser beam focusing mirror 62. The laser beam focusing mirror 62 may be positioned to focus the laser beam from the high-reflection mirror 61 in the plasma generation region 25. In the plasma generation region 25, a target supplied from the target supply device 26 (see FIG. 1) may be irradiated with the laser beam, and the target is turned into plasma from which light including EUV light may be emitted. As described above, in the first embodiment, the laser beam introduction optical system 50 that includes the beam splitter 52 and the high-reflection mirror 53 may be fixed and positioned to the reference member 9 through the positioning mechanism 10 relative to the laser beam focusing optical system 60. The laser beam focusing optical system 60 may then be positioned relative to the EUV collector mirror 23, which in turn may be positioned relative to the exposure apparatus 6 with the plasma generation region 25 and the intermediate focus 292 serving as references. Accordingly, a target may be irradiated with the laser beam with high precision, and emitted EUV light may stably be supplied to the exposure apparatus 6. FIG. 3A is a plan view illustrating an EUV light generation apparatus according to a second embodiment of the present disclosure. FIG. 3B is a sectional view of the EUV light generation apparatus shown in FIG. 3A, taken along plane. As shown in FIGS. 3A and 3B, the positioning mechanism 10 for positioning the beam splitter 52, the high-reflection mirror 53, and the laser beam measuring unit 37 to the reference member 9 may include a support plate 10a. The beam splitter 52, the high-reflection mirror 53, and the laser beam measuring unit 37 may be supported on the upper surface of the support plate 10a through respective holders. The laser beam measuring unit 37 is not shown in FIG. 3B. Three legs 71 through 73 may be attached on the lower surface of the support plate 10a to support the support plate 10a at three points. The lower end of each of the legs 71 through 73 may be hemispherical in shape. The leg 71 may be provided at a position directly underneath the beam splitter 52. The leg 72 may be provided at a position distanced from the leg 71 in a direction in which a laser beam travels from the beam splitter 52 to the high-reflection mirror 53. The leg 72 may be provided directly underneath the beam axis of the laser beam. The leg 73 may be provided at a position distanced in the Y-direction from an imaginary line connecting the leg 71 and the leg 72. The positioning mechanism 10 may further include mounts 81 through 83, on which the legs 71 through 73 are placed, respectively. The mounts 81 through 83 may be fixed in the housing chamber 9b of the reference member 9. The legs 71 through 73 may be placed on the respective mounts 81 through 83, and thus the support plate 10a may be supported on the reference member 9. A conical recess may be formed on the upper surface of the mount 81. A V-shaped groove may be formed on the upper surface of the mount 82. The groove in the mount 82 may be formed in a direction parallel to the beam axis of the laser beam from the beam splitter 52 to the high-reflection mirror 53. The upper surface of the mount 83 may be planar. The leg 71 may be placed on the mount 81 having a conical recess, and thus the leg 71 may be restricted from moving along the XY plane. The leg 72 may be placed on the mount 82 having a V-shaped groove, and thus the leg 72 may be supported movably in the X-direction. That is, the leg 72 may be supported movably along the direction in which the laser beam travels from the beam splitter 52 to the high-reflection mirror 53. The leg 73 may be placed on the mount 83, and thus the leg 73 may be supported movably along the XY plane. Through the above-described configuration, even if the support plate 10a deforms due to thermal expansion, the direction of the laser beam may be prevented from being changed inside the housing chamber 9b. Because of shapes of the mounts 81 through 83, for example, the support plate 10a may be allowed to expand along the path of the laser beam. Thus, the laser beam introduction optical system 50 may be positioned with precision relative to the laser beam focusing optical system 60 and the plasma generation region 25. Accordingly, a target may be irradiated with the laser beam with high precision, and an output of EUV light may be stabilized. FIG. 4A is a plan view illustrating an EUV light generation apparatus according to a third embodiment of the present disclosure. FIG. 4B is a sectional view of the EUV light generation apparatus shown in FIG. 4A, taken along IVB-IVB plane. In the third embodiment, the beam splitter 52, the high-reflection mirror 53, and the laser beam measuring unit 37 may be supported on the lower surface of the support plate 10a through respective holders. The laser beam measuring unit 37 is not shown in FIG. 4B. A through-hole 54 may be formed in the holder supporting the high-reflection mirror 53 through which a laser beam may pass. Hooks 71b through 73b may be attached on the upper surface of the support plate 10a. Each of the hooks 71b through 73b may have a hemispherical projection. The hook 71b may be provided such that the hemispherical projection thereof is located directly above the beam splitter 52. The hook 72b may be provided such that the hemispherical projection thereof is located at a position distanced from the hook 71b in a direction in which a laser beam travels from the beam splitter 52 to the high-reflection mirror 53. The hemispherical projection of the hook 72b may be located directly above the beam axis of the laser beam. The hook 73b may be provided at a position distanced in the Y-direction from an imaginary line connecting the hook 71b and the hook 72b. The positioning mechanism 10 may include mounts 81b through 83b, on which the hooks 71b through 73b are placed, respectively. The mounts 81b through 83b may be suspended and fixed inside the housing chamber 9b of the reference member 9. The hooks 71b through 73b may be placed on the respective mounts 81b through 83b, and thus the support plate 10a may be supported by the reference member 9. A conical recess may be formed on the upper surface of the mount 81b. A V-shaped groove may be formed on the upper surface of the mount 82b. The groove in the mount 82b may be formed in a direction parallel to the beam axis of the laser beam from the beam splitter 52 to the high-reflection mirror 53. The upper surface of the mount 83b may be planar. FIG. 5A is a plan view illustrating an EUV light generation apparatus according to a fourth embodiment of the present disclosure. FIG. 5B is a sectional view of the EUV light generation apparatus shown in FIG. 5A, taken along VB-VB plane. In the fourth embodiment, the upper surfaces of mounts 81c through 83c of the positioning mechanism 10 may be planar. Biasing members 74c and 75c may be attached to the support plate 10a on a side surface that is parallel to the YZ plane. A V-shaped groove may be formed on a side surface of the biasing member 74c in the Z-direction, which corresponds to the direction of gravitational force. A side surface of the biasing member 75c may be planar. The positioning mechanism 10 may include columnar stoppers 84c and 85c. Each of the stoppers 84c and 85c may be fixed at one end thereof in the housing chamber 9b of the reference member 9 such that the axis of each of the stoppers 84c and 85c coincides with the direction of gravitational force. The biasing member 75c and the stopper 85c are not shown in FIG. 5B. The legs 71 through 73 each having a hemispherical bottom may be placed on the mounts 81c through 83c each having a planar upper surface, and thus the support plate 10a may not easily move in the Z-direction and may not easily rotate about the X-axis or the Y-axis. The biasing member 74c having the V-shaped groove may be biased against the stopper 84c, and thus the support plate 10a may be rotatably supported about the Z-axis. The biasing member 75c may be biased against the stopper 85c, and thus the support plate 10a may be positioned relative to the reference member 9. An elastic member 76c may be attached to the support plate 10a at a position between the biasing member 74c and the biasing member 75c. The elastic member 76c may be a spring. When the biasing members 74c and 75c are biased against the stoppers 84c and 85c, respectively, the biasing member 76c may be biased against a stopper 86c fixed inside the housing chamber 9b of the reference member 9. Thus, shock that occurs when the biasing members 74c and 75c are biased against the stoppers 84c and 85c may be absorbed. An elastic member 77c may be attached to the support plate 10a at a position opposite from the elastic member 76c. The elastic member 77c may be a spring. When the housing chamber 9b is closed by the lid 9c, a pressing member 87c may bias the elastic member 77c. Thus, when the housing chamber 9b is closed by the lid 9c, the biasing members 74c and 75c may be biased against the stoppers 84c and 85c, respectively. Accordingly, the laser beam introduction optical system 50 supported by the support plate 10a may be positioned relative to the reference member 9. FIG. 6A is a plan view illustrating an EUV light generation apparatus according to a fifth embodiment of the present disclosure. FIG. 6B is a sectional view of the EUV light generation apparatus shown in FIG. 6A, taken along VIB-VIB plane. The housing chamber 9a (see FIGS. 2B, 3B, 4B, and 5B) that is in communication with the chamber 2 may not be provided in the reference member 9, and only the housing chamber 9b may be provided in the reference member 9. The window 38 may be provided in the reference member 9 to provide an airtight seal between the housing chamber 9b and the chamber 2 while allowing a laser beam to enter the chamber 2. A laser beam focusing optical system 63 may be supported by the support plate 10a of the positioning mechanism 10 in the housing chamber 9b through a holder 631. The laser beam focusing optical system 63 may include at least one mirror, at least one lens, or a combination thereof. The arrangement of the legs 71 through 73 and the mounts 81 through 83 for supporting the support plate 10a may be the same as that in the second embodiment. In the fifth embodiment, the laser beam introduction optical system 50 that includes the beam splitter 52 and the high-reflection mirror 53 and the laser beam focusing optical system 63 may altogether be positioned to the reference member 9 through the positioning mechanism 10. Thus, the laser beam focusing optical system 63 and the laser beam introduction optical system 50 may be positioned with precision relative to the plasma generation region 25. Accordingly, a target may be irradiated with the laser beam with high precision, and an output of EUV light may be stabilized. FIG. 7A is a plan view illustrating an EUV light generation apparatus according to a sixth embodiment of the present disclosure. FIG. 7B is a sectional view of the EUV light generation apparatus shown in FIG. 7A, taken along VIIB-VIIB plane. In the sixth embodiment, a backpropagating beam measuring unit 39 may be supported on the upper surface of the support plate 10a of the positioning mechanism 10 through a holder. The backpropagating beam measuring unit 39 may be positioned such that a backpropagating beam from the plasma generation region 25 is incident on the photosensitive surface thereof through the high-reflection mirror 53 and the beam splitter 52. The backpropagating beam from the plasma generation region 25 may include a part of a laser beam reflected by a target. An imaging optical system (not separately shown) may be provided between the beam splitter 52 and the backpropagating beam measuring unit 39 to form an image of a target irradiated with the laser beam on the photosensitive surface of the backpropagating beam measuring unit 39. Measuring the backpropagating beam with the backpropagating beam measuring unit 39 may enable to determine whether or not a target has been irradiated with a laser beam at its focus. The leg 71 may be provided at a position immediately underneath the high-reflection mirror 53. The leg 72 may be provided at a position immediately underneath the backpropagating beam measuring unit 39. In the sixth embodiment, the laser beam introduction optical system 50 that includes the beam splitter 52 and the high-reflection mirror 53 and the backpropagating beam measuring unit 39 may altogether be fixed to the reference member 9 and positioned relative to each other through the positioning mechanism 10 so that the positional relationship among the beam splitter 52, the high-reflection mirror 53, and the backpropagating beam measuring unit 39 does not vary. Accordingly, the backpropagating beam from the plasma generation region 25 may stably be measured with the back propagating beam measuring unit 39. FIG. 8A is a front view illustrating the interior of a reference member of an EUV light generation apparatus according to a seventh embodiment of the present disclosure. FIG. 8B is a sectional view of the reference member shown in FIG. 8A, taken along VIIIB plane. FIG. 8C is a front view illustrating the interior of the reference member shown in FIG. 8A in a state where a laser beam introduction optical system 50 is positioned to the reference member. FIG. 8D is a sectional view of the reference member shown in FIG. 8C, taken along VIIID-VIIID plane. As shown in FIGS. 8A through 8D, a moving mechanism that includes a pair of rails 41 and 42 and driving mechanisms 43 and 44 may be provided in the housing chamber 9b of the reference member 9. The rails 41 and 42 may be arranged parallel to each other and at the same height. The driving mechanisms 43 and 44 may be configured to move the rails 41 and 42 vertically at the same rate. Wheels 101a and 101b may be provided on the support plate 10a to be movable along the rail 41, and a wheel 102 and another wheel (not separately shown) may be provided on the support plate 10a to be movable along the rail 42. The legs 71 through 73 may be attached on the lower surface of the support plate 10a. The mounts 81 through 83, on which the legs 71 through 73 are placed, respectively, may be fixed inside the housing chamber 9b of the reference member 9. A conical recess may be formed on the upper surface of the mount 81. A V-shaped groove may be formed on the upper surface of the mount 82. The upper surface of the mount 83 may be planar. Moving the wheels 101a, 101b, and 102a along the rails 41 and 42 may allow the support plate 10a to move. When the leg 71 of the support plate 10a reaches above the mount 81, the driving mechanisms 43 and 44 may lower the rails 41 and 42, respectively (see FIGS. 8C and 8D). Thus, the legs 71 through 73 may be placed on the mounts 81 through 83, respectively, and the laser beam introduction optical system 50 that includes the beam splitter 52 and the high-reflection mirror 53 may be positioned to the reference member 9. Thereafter, the housing chamber 9b may be closed by the lid 9c (see FIG. 3B). When the laser beam introduction optical system 50 is replaced or maintenance work is carried out on the laser beam introduction optical system 50, the driving mechanisms 43 and 44 may raise the rails 41 and 42, respectively. Thereafter, by moving the support plate 10a along the rails 41 and 42, the laser beam introduction optical system 50 that includes the beam splitter 52 and the high-reflection mirror 53 may be removed from the housing chamber 9b. According to the seventh embodiment, a work load for positioning the laser beam introduction optical system 50 to the reference member 9 and a work load for removing the laser beam introduction optical system 50 from the chamber 9 may be reduced. FIG. 9A is a front view illustrating the interior of a reference member of an EUV light generation apparatus according to an eighth embodiment of the present disclosure. FIG. 9B is a sectional view of the reference member shown in FIG. 9A, taken along IXB-IXB plane. FIG. 9C is a front view illustrating the interior of the reference member shown in FIG. 9A in a state where a laser beam introduction optical system 50 is positioned to the reference member. FIG. 9D is a sectional view of the reference member shown in FIG. 9C, taken along IXD-IXD plane. In the eighth embodiment, the support plate 10a may be moved vertically relative to the wheels 101a, 101b, and 102a. The rails 41 and 42 may be fixed to the bottom of the housing chamber 9b to be parallel to each other. Driving mechanisms 103a, 103b, and 104a, and another driving mechanism (not separately shown) may be provided to the support plate 10a to move the support plate 10a vertically with respect to the wheels 101a, 101b, 102a, and another wheel (not separately shown), respectively. Moving the wheels 101a, 101b, and 102a along the rails 41 and 42 may allow the support plate 10a to move. When the leg 71 of the support plate 10a reaches above the mount 81, the driving mechanisms 103a, 103b, and 104a may lower the support plate 10a (see FIGS. 9C and 9D). Thus, the support plate 10a may be lowered, and the legs 71 through 73 may be placed on the mounts 81 through 83, respectively. Accordingly, the laser beam introduction optical system 50 that includes the beam splitter 52 and the high-reflection mirror 53 may be positioned to the reference member 9. Thereafter, the housing chamber 9b may be closed by the lid 9c (see FIG. 3B). At this point, the wheels 101a, 101b, and 102a may not need to be in contact with the rails 41 and 42. When the laser beam introduction optical system 50 is replaced or maintenance work is carried out on the laser beam introduction optical system 50, the driving mechanisms 103a, 103b, and 104a may raise the support plate 10a. Thereafter, by moving the support plate 10a along the rails 41 and 42, the laser beam introduction optical system 50 that includes the beam splitter 52 and the high-reflection mirror 53 may be removed from the housing chamber 9b. FIG. 10A is a front view illustrating the interior of a reference member of an EUV light generation apparatus according to a ninth embodiment of the present disclosure. FIG. 10B is a sectional view of the reference member shown in FIG. 10A, taken along XB-XB plane. FIG. 10C is a plan view illustrating the reference member shown in FIG. 10A in a state where a laser beam introduction optical system 50 is positioned to the reference member. FIG. 10D is a front view of the interior of the reference member shown in FIG. 10C. FIG. 10E is a sectional view of the reference member shown in FIG. 10D, taken along XE-XE plane. As shown in FIGS. 10A through 10E, a moving mechanism that includes the pair of rails 41 and 42 may be provided in the housing chamber 9b of the reference member 9. The rails 41 and 42 may be arranged parallel to each other and at the same height. Wheels 101c and 101d may be provided to the support plate 10a to be movable along the rail 41, and wheels 102c and 102d may be provided to the support plate 10a to be movable along the rail 42. As the wheels 101c, 101d, 102c, and 102d may move on the rails 41 and 42, the support plate 10a may be moved. Legs 71e through 73e may be attached on the lower surface of the support plate 10a. A ball bearing (not separately shown) may be provided at the lower end of each of the legs 71e through 73e. Slopes 81f through 83f may be provided adjacent to mounts 81e through 83e having planar upper surfaces. When the support plate 10a is moved to the right in FIG. 10B, the legs 71e through 73e may come into contact with the slopes 81f through 83f, respectively. As the support plate 10a is further moved, the legs 71e through 73e may run on the slopes 81f through 83f, respectively. Then, the wheels 101c and 102c may be distanced from the rails 41 and 42. Meanwhile, the wheels 101d and 102d may move while being in contact with the side surfaces of the rails 41 and 42, respectively. When the support plate 10a is moved even further, the legs 71e through 73e may move along the slopes 81f through 83f to reach the planar upper surfaces of the respective mounts 81e through 83e. Then, as in the fourth embodiment, the biasing members 74c and 75c may be biased against the stoppers 84c and 85c, respectively, and thus the laser beam introduction optical system 50 that includes the beam splitter 52 and the high-reflection mirror 53 may be positioned to the reference member 9. Here, since the laser beam introduction optical system 50 is positioned by biasing the biasing members 74c and 75c against the stoppers 84c and 85c, the wheels 101d and 102d may not need to be in contact with the side surfaces of the rails 41 and 42, respectively. FIG. 11A is a partial sectional view illustrating a reference member and a moving mechanism of an EUV light generation apparatus according to a tenth embodiment of the present disclosure. FIG. 11B is a partial sectional view illustrating the reference member shown in FIG. 11A in a state where a laser beam introduction optical system 50 is positioned to the reference member. As shown in FIGS. 11A and 11B, the moving mechanism may include a dolly 110. The dolly 110 may include a frame 111, wheels 112, a stay 113, a rail 114, drive units 115, and a support 116. The dolly 110 may be moved as the wheels 112 roll on the floor. The stay 113 may be fixed to the frame 111 to stand vertically with respect to the floor surface. The drive units 115 may move the rail 114 vertically with respect to the frame 111. Directions in which the rail 114 is movable may be regulated by the stay 113. The rail 114 may be provided to be horizontal with respect to the floor surface and vertically movable with respect to the frame 111. The support 116 may be movable along the rail 114. The support 116 may hold the support plate 10a thereon. The support 116 holding the support plate 10a may move along the rail 114 to move the support plate 10a. When the support plate 10a moves along the rail 114 and the legs 71 through 73 reach above the respective mounts 81 through 83, the drive units 115 may lower the rail 114 (see FIG. 11B). Thus, the legs 71 through 73 may be placed on the mounts 81 through 83, respectively, and the laser beam introduction optical system 50 that includes the beam splitter 52 and the high-reflection mirror 53 may be positioned to the reference member 9. Thereafter, the drive units 115 may further lower the rail 114. Then, the support plate 10a may be separated from the support 116 to allow the dolly 110 to be removed. When the laser beam introduction optical system 50 is replaced or maintenance work is carried out on the laser beam introduction optical system 50, the dolly 110 may be arranged at the position shown in FIG. 11B, and the drive units 115 may raise the rail 114. Thereafter, by moving the support 116 holding the support plate 10a along the rail 114, the laser beam introduction optical system 50 that includes the beam splitter 52 and the high-reflection mirror 53 may be removed from the housing chamber 9b. According to the tenth embodiment, a work load for positioning the laser beam introduction optical system 50 to the reference member 9 and a work load for removing the laser beam introduction optical system 50 from the reference member 9 may be reduced. FIG. 12A is a partial sectional view illustrating a reference member and a moving mechanism of an EUV light generation apparatus according to an eleventh embodiment of the present disclosure. FIG. 12B is a partial sectional view illustrating the reference member shown in FIG. 12A in a state where a laser beam introduction optical system 50 is positioned to the reference member. As shown in FIGS. 12A and 12B, the moving mechanism may include the dolly 110. The configuration of the dolly 110 may be similar to that in the tenth embodiment. According to the eleventh embodiment, a work load for positioning the laser beam introduction optical system 50 to the reference member 9 and a work load for removing the laser beam introduction optical system 50 from the reference member 9 may be reduced. FIG. 13A is a plan view illustrating an EUV light generation apparatus according to a twelfth embodiment of the present disclosure. FIG. 13B is a sectional view of the EUV light generation apparatus shown in FIG. 13A, taken along XIIIB-XIIIB plane. In the twelfth embodiment, a target may be irradiated with a pre-pulse laser beam to be diffused, and the diffused target may then be irradiated with a main pulse laser beam to be turned into plasma. For example, a yttrium aluminum garnet (YAG) laser apparatus that oscillates at a wavelength of 1.06 μm may be used as a pre-pulse laser apparatus, and a carbon-dioxide (CO2) laser apparatus that oscillates at a wavelength of 10.6 μm may be used as a main pulse laser apparatus. As shown in FIG. 13A, a pre-pulse laser apparatus 3a and a main pulse laser apparatus 3b may be provided to output a pre-pulse laser beam and a main pulse laser beam, respectively. Optical pipes 66a and 66b may be attached to the reference member 9 through flexible pipes 68a and 68b, respectively. High-reflection mirrors 67a and 67b may be provided in the optical pipes 66a and 66b, respectively. The optical pipes 66a and 66b may be connected to the laser apparatuses 3a and 3b, respectively. A beam splitter 58, a high-reflection mirror 59, the beam splitter 52, the high-reflection mirror 53, the laser beam measuring unit 37, and the backpropagating beam measuring unit 39 may be supported on the upper surface of the support plate 10a of the positioning mechanism 10 through respective holders. The leg 71 to be placed on the mount 81 having a conical recess may be provided at a position immediately underneath the high-reflection mirror 53. The leg 72 to be placed on the mount 82 having a V-shaped groove may be provided at a position immediately underneath the high-reflection mirror 59. The beam splitter 58 may transmit the pre-pulse laser beam with high transmittance. The high-reflection mirror 59 may reflect the main pulse laser beam with high reflectance. The pre-pulse laser beam transmitted through the beam splitter 58 may be incident on a first surface of the beam splitter 52. The main pulse laser beam reflected by the high-reflection mirror 59 may be incident on a second surface of the beam splitter 52. The beam splitter 52 may reflect the pre-pulse laser beam incident on the first surface thereof toward the high-reflection mirror 53 with high reflectance. The beam splitter 52 may transmit a part of the pre-pulse laser beam incident on the first surface thereof toward the laser beam measuring unit 37. Further, the beam splitter 52 may transmit the main pulse laser beam incident on the second surface thereof toward the high-reflection mirror 53 with high transmittance. The beam splitter 52 may reflect a part of the main pulse laser beam incident on the second surface thereof toward the laser beam measuring unit 37. The laser beam measuring unit 37 may have a photosensitive surface sensitive to both the wavelength of the pre-pulse laser beam and the wavelength of the main pulse laser beam. The beam splitter 52 may serve as a beam combiner for controlling the direction in which the pre-pulse laser beam travels and the direction in which the main pulse laser beam travels to coincide with each other. The beam splitter 52 may, for example, be formed of diamond. The high-reflection mirror 53 may reflect the pre-pulse laser beam reflected by the beam splitter 52 and the main pulse laser beam transmitted through the beam splitter 52 with high reflectance. The pre-pulse laser apparatus 3a and the main pulse laser apparatus 3b may be controlled so that the main pulse laser beam is outputted when a predetermined time elapses after the pre-pulse laser beam is outputted. The pre-pulse laser beam and the main pulse laser beam sequentially reflected by the high-reflection mirror 53 may be transmitted through the window 38 with high transmittance, and reflected by the high-reflection mirror 61 with high reflectance. Then, the pre-pulse laser beam and the main pulse laser beam may be focused on a target and a diffused target, respectively, in the plasma generation region 25 by the laser beam focusing mirror 62. A backpropagating beam from the plasma generation region 25 may be incident on the photosensitive surface of the backpropagating beam measuring unit 39 through the high-reflection mirror 53, the beam splitter 52, and the beam splitter 58. An imaging optical system (not separately shown) may be provided between the beam splitter 58 and the backpropagating beam measuring unit 39 to form an image of a target irradiated with the pre-pulse laser beam on the photosensitive surface of the backpropagating beam measuring unit 39. Measuring the backpropagating beam with the backpropagating beam measuring unit 39 may enable to determine whether or not a target has been irradiated with the pre-pulse laser beam at its focus. According to the twelfth embodiment, even in a case where a target is irradiated with a pre-pulse laser beam and a diffused target is then irradiated with a main pulse laser beam, the target and the diffused target may be irradiated respectively with the pre-pulse laser beam and the main pulse laser beam with high precision. FIG. 14 illustrates an exemplary configuration of a laser beam measuring unit of the twelfth embodiment. The beam splitter 52 may be positioned such that a pre-pulse laser beam is incident on the first surface thereof and a main pulse laser beam is incident on the second surface thereof. The pre-pulse laser beam may be reflected by the first surface of the beam splitter 52, and the main pulse laser beam may be transmitted through the beam splitter 52. The pre-pulse laser beam reflected by the beam splitter 52 and the main pulse laser beam transmitted through the beam splitter 52 may be guided into the chamber 2. Meanwhile, a part of the pre-pulse laser beam may be transmitted through the beam splitter 52, and a part of the main pulse laser beam may be reflected by the second surface of the beam splitter 52. The transmitted part of the pre-pulse laser beam and the reflected part of the main pulse laser beam may be incident on a beam splitter 52a as sample beams. The beam splitter 52a and a high-reflection mirror 52b may be provided in a beam path of the sample beams. The beam splitter 52a may reflect the pre-pulse laser beam with high reflectance and transmit the main pulse laser beam with high transmittance. The high-reflection mirror 52b may reflect the main pulse laser beam with high reflectance. A beam splitter 78a, a focusing optical system 79a, a transfer optical system 80a, and beam profilers 56a and 57a may be provided in a beam path of the pre-pulse laser beam reflected by the beam splitter 52a. The beam splitter 78a may be configured to transmit a part of the sample beam toward the transfer optical system 80a and reflect the other part toward the focusing optical system 79a. The transfer optical system 80a may transfer a beam profile at a position A1 in a beam path of the sample beam onto the photosensitive surface of the beam profiler 57a. The focusing optical system 79a may focus the sample beam reflected by the beam splitter 78a on the photosensitive surface of the beam profiler 56a. The beam profiler 56a may be provided at a position distanced from the focusing optical system 79a by a predetermined distance F. The predetermined distance F may be the focal distance of the focusing optical system 79a. Each of the beam profilers 56a and 57a may output data on a beam profile such as a beam intensity distribution based on the sample beams received on the respective photosensitive surfaces thereof to a controller 90. The controller 90 may calculate a beam width of the sample beam at the position A1 from an output of the beam profiler 57a. Further, the controller 90 may calculate the spot width of the sample beam from an output of the beam profiler 56a. The controller 90 may then calculate the travel direction and the wavefront curvature of the sample beam from the calculation results. Similarly, a beam splitter 78b, a focusing optical system 79b, a transfer optical system 80b, and beam profilers 56b and 57b may be provided in a beam path of the main pulse laser beam reflected by the high-reflection mirror 52b. Thus, the travel direction and the wavefront curvature of the main pulse laser beam may be obtained. FIG. 15A is a plan view illustrating an EUV light generation apparatus according to a thirteenth embodiment of the present disclosure. FIG. 15B is a sectional view of the EUV light generation apparatus shown in FIG. 15A, taken along XVB-XVB plane. In the thirteenth embodiment, a box 9d may be connected to the housing chamber 9b formed in the reference member 9 through a flexible pipe 68c. The high-reflection mirror 53 may be provided in the housing chamber 9b. The beam splitter 58, the high-reflection mirror 59, the beam splitter 52, the laser beam measuring unit 37, and the backpropagating beam measuring unit 39 may be provided in the box 9d. The legs 71 through 73 may be attached on the lower surface of the box 9d. The leg 72 is not shown in FIG. 15B. The mounts 81 through 83 on which the legs 71 through 73 are placed may be fixed on the outer surface of the reference member 9. The leg 71 to be placed on the mount 81 having a conical recess may be provided at a position immediately underneath the beam splitter 58. The leg 72 to be placed on the mount 82 having a V-shaped groove may be provided at a position immediately underneath the laser beam measuring unit 37. The groove in the mount 82 may be formed in a direction parallel to the beam axis of the laser beam from the beam splitter 52 to the laser beam measuring unit 37 (see, e.g., 82 in FIG. 13B). Thus, the box 9d may be positioned to the reference member 9. The optical pipes 66a and 66b may be attached to the box 9d through the flexible pipes 68a and 68b, respectively. The high-reflection mirrors 67a and 67b may be provided in the optical pipes 66a and 66b, respectively. The optical pipes 66a and 66b may be connected to the pre-pulse laser apparatus 3a and the main pulse laser apparatus 3b, respectively. At least one eye bolt 9e serving as a moving mechanism may be attached to the box 9d to lift the box 9d. When maintenance work is carried out, the flexible pipe 68c may be detached from the box 9d, and a hook of a crane may be engaged with the eye bolt 9e to move the box 9d housing the laser beam introduction optical system 50. The above-described embodiments and the modifications thereof are merely examples for implementing the present disclosure, and the present disclosure is not limited thereto. Making various modifications according to the specifications or the like is within the scope of the present disclosure, and other various embodiments are possible within the scope of the present disclosure. For example, the modifications illustrated for particular ones of the embodiments can be applied to other embodiments as well (including the other embodiments described herein). The terms used in this specification and the appended claims should be interpreted as “non-limiting.” For example, the terms “include” and “be included” should be interpreted as “including the stated elements but not limited to the stated elements.” The term “have” should be interpreted as “having the stated elements but not limited to the stated elements.” Further, the modifier “one (a/an)” should be interpreted as “at least one” or “one or more.” |
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description | The subject application is a continuation of U.S. patent application Ser. No. 16/453,951, filed Jun. 26, 2019, which is a continuation of U.S. patent application Ser. No. 15/600,536, filed May 19, 2017, now U.S. Pat. No. 10,375,814, which is a continuation of PCT Patent Application No. PCT/US15/61356, filed Nov. 18, 2015, which claims priority to Russian Patent Application No. 2014146574, filed on Nov. 19, 2014, all of which are incorporated by reference herein in their entireties for all purposes. The subject matter described herein relates generally to neutral beam injectors and, more particularly, to a photon neutralizer for a neutral beam injector based on negative ions. A traditional approach to produce a neutral beam from a negative ion H−, D− beam for plasma heating or neutral beam assisted diagnostics, is to neutralize the negative ion beam in a gas or plasma target for detachment of the excess electrons. However, this approach has a significant limitation on efficiency. At present, for example, for designed heating injectors with a 1 MeV beam [R. Hemsworth et al., 2009, Nucl. Fusion 49 045006], the neutralization efficiency in the gas and plasma targets will be about 60% and 85%, respectively [G. I. Dimov et al., 1975, Nucl. Fusion 15, 551], which considerably affects the overall efficiency of the injectors. In addition, the application of such neutralizers is associated with complications, including the deterioration of vacuum conditions due to gas puffing and the appearance of positive ions in the atomic beam, which can be significant in some applications. Photodetachment of an electron from high-energy negative ions is an attractive method of beam neutralization. Such method does not require a gas or plasma puffing into the neutralizer vessel, it does not produce positive ions, and it assists with beam cleaning of fractions of impurities due to negative ions. The photodetachment of an electron corresponds to the following process: H−+hω=H0+e. Similar to most negative ions, the H− ion has a single stable state. Nevertheless, photodetachment is possible from an excited state. The photodetachment cross section is well known [see, e.g., L. M. Branscomb et al., Phys. Rev. Lett. 98, 1028 (1955)]. The photodetachment cross section is large enough in a broad photon energy range which practically overlaps all visible and near IR spectrums. Such photons cannot knock out an electron from H0 or all electrons from H− and produce positive ions. This approach was proposed in 1975 by J. H. Fink and A. M. Frank [J. H. Fink et al., Photodetachment of electrons from negative ions in a 200 keV deuterium beam source, Lawrence Livermore Natl. Lab. (1975), UCRL-16844]. Since that time a number of projects for photon neutralizers have been proposed. As a rule, the photon neutralizer projects have been based on an optic resonator similar to Fabri-Perot cells. Such an optic resonator needs mirrors with very high reflectance and a powerful light source with a thin line, and all of the optic elements need to be tuned very precisely. For example, in a scheme considered by Kovari [M. Kovari et al., Fusion Engineering and Design 85 (2010) 745-751], the reflectance of the mirrors is required to be not less than 99.96%, the total laser output power is required to be about 800 kW with output intensity of about 300 W/cm2, and the laser bandwidth is required to be less than 100 Hz. It is unlikely that such parameters could be realized together. Therefore, it is desirable to provide a non-resonance photo-neutralizer. Embodiments provided herein are directed to systems and methods for a non-resonance photo-neutralizer for negative ion-based neutral beam injectors. The non-resonance photo-neutralizer described herein is based on the principle of nonresonant photon accumulation, wherein the path of the photon becomes tangled and trapped in a certain space region, i.e., the photon trap. The trap is preferably formed as two smooth mirror surfaces facing each other with at least one surface being concave. In the simplest form, the trap is preferably elliptical in shape. A confinement region of the trap is a region near a family of normals that are common to both mirror surfaces of the trap. The photons with a sufficiently small angle of deviation from the nearest common normal are confined. Depending on specific conditions, the shape of the trap may be one of spherical, elliptical, cylindrical, toroidal, or a combination thereof. In operation, photon beams with a given angular spread along and across the trap are injected through one or more small holes in one or more of the mirrors. The photon beams can be from standard industrial power fiber lasers. The photo neutralizer does not require high quality laser radiation sources pumping a photon target, nor does it require very high precision adjustment and alignment of the optic elements Other systems, methods, features and advantages of the example embodiments will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. It should be noted that elements of similar structures or functions are generally represented by like reference numerals for illustrative purpose throughout the figures. It should also be noted that the figures are only intended to facilitate the description of the preferred embodiments. Each of the additional features and teachings disclosed below can be utilized separately or in conjunction with other features and teachings to provide a non-resonance photo-neutralizer for negative ion-based neutral beam injectors. Representative examples of the embodiments described herein, which examples utilize many of these additional features and teachings both separately and in combination, will now be described in further detail with reference to the attached drawings. This detailed description is merely intended to teach a person of skill in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the invention. Therefore, combinations of features and steps disclosed in the following detail description may not be necessary to practice the invention in the broadest sense, and are instead taught merely to particularly describe representative examples of the present teachings. Moreover, the various features of the representative examples and the dependent claims may be combined in ways that are not specifically and explicitly enumerated in order to provide additional useful embodiments of the present teachings. In addition, it is expressly noted that all features disclosed in the description and/or the claims are intended to be disclosed separately and independently from each other for the purpose of original disclosure, as well as for the purpose of restricting the claimed subject matter independent of the compositions of the features in the embodiments and/or the claims. It is also expressly noted that all value ranges or indications of groups of entities disclose every possible intermediate value or intermediate entity for the purpose of original disclosure, as well as for the purpose of restricting the claimed subject matter. Embodiments provided herein are directed to a new non-resonance photo-neutralizer for negative ion-based neutral beam injectors. A detailed discussion of a negative ion-based neutral beam injector is provided in Russian Patent Application No. 2012137795 and PCT Application No. PCT/US2013/058093, which are incorporated herein by reference. The non-resonance photo-neutralizer described herein is based on the principle of nonresonant photon accumulation, wherein the path of the photon becomes tangled and trapped in a certain space region, i.e., the photon trap. The trap is preferably formed as two smooth mirror surfaces facing each other with at least one surface being concave. In the simplest form, the trap is preferably elliptical in shape. A confinement region of the trap is a region near a family of normals that are common to both mirror surfaces of the trap. The photons with a sufficiently small angle of deviation from the nearest common normal are confined. Depending on specific conditions, the shape of the trap may be one of spherical, elliptical, cylindrical, toroidal, or a combination thereof. In operation, photon beams with a given angular spread along and across the trap are injected through one or more small holes in one or more of the mirrors. The photon beams can be from standard industrial power fiber lasers. The photo neutralizer does not require high quality laser radiation sources pumping a photon target, nor does it require very high precision adjustment and alignment of the optic elements. Turning to the figures, an embodiment of a non-resonance photon trap 10 is shown in FIG. 1. As depicted in a two-dimensional case, the trap 10 comprises a bottom flat mirror 20 and a top concave mirror 30. A photon γ with a small angle to vertical axes within the trap 10, will develop with each reflection from the upper mirror 30 some horizontal momentum difference to central axes of trap 10. The position of the photon γ after an n-th reflection is defined by the abscissa of a reflection point, xn, with a height, F(xn), an angle φ from a vertical and a photon speed, βn. The horizontal motion is described by the following system of equations: x n + 1 - x n = ( F ( x n + 1 ) + F ( x n ) ) tg β n ( 1 ) β n + 1 - β n = 2 dF ( x n + 1 ) dx ( 2 ) For stability investigation, linearize versions of equations (1) and (2) are combined and the following equations are obtained: x n + 1 - x n = 2 F ( 0 ) β n ( 3 ) β n + 1 - β n = 2 d 2 F ( 0 ) dx 2 x n + 1 ( 4 ) By combining equations (3) and (4), the following linear recurrence relation is obtained: x n + 2 - 2 x n + 1 + x n = 4 F ( 0 ) d 2 F ( 0 ) dx 2 x n + 1 = - 4 F ( 0 ) x n + 1 R , ( 5 ) where R is the curvature radius of top mirror 30. Equation (5) is a type of finite-difference scheme for an oscillation system with unit time step and with Eigen frequency ω 0 = 2 F ( 0 ) R . The solution is representable in the form xn=A·qn, where q is a complex number. Then for q defined as: q 1 , 2 = 1 - 2 F ( 0 ) R ± ( 1 - 2 F ( 0 ) R ) 2 - 1 , ( 6 ) The stability condition is |q|≤1, from which photons confinement in a geometric optic, when taking into account non-negativity of value F ( 0 ) R ,is determined asF(0)<R,ωo2<4 (7)The curvature radius of the upper mirror 30 impacts photon confinement. Recurrent systems (1) and (2) allow the production of the integral of motion: ∑ n tg β n ( β n + 1 - β n ) = ∑ n 2 ( x n + 1 - x n ) F ( x n + 1 ) + F ( x n ) dF ( x n + 1 ) dx , ( 8 ) In the case of a sufficiently small curvature of the upper mirror 30 and small steps, such as Δ F << F , dF dx << 1 , Δβ << 1 , ( 9 ) the integral sums (8) is approximately transformed into ln cos β 0 cos β = ln F ( x ) F ( x 0 ) or into standard adiabatic invariantF(x)cos(β)=const (10)Relation (10) determines the region filled by photons. These estimations enable the design of an effective photon neutralizer for negative ion beams. Turning to FIGS. 2 and 3, a reasonable three-dimensional geometry of the trap 10 is a long arch assembly of four components. As depicted in FIG. 2, the trap 10 preferably comprises a bottom or lower mirror 20 at the bottom of the trap 10 that is planar or flat in shape, and an upper mirror assembly 30 comprising a central mirror 32 that is cylindrical in shape, and a pair of outer mirrors 34 that are conical in shape and coupled to the ends of the central mirror 32. As shown, an ion beam H− is passed along the photon trap. The sizes are taken from the characteristic scales of a single neutralizer channel of a beam injector for the International Thermonuclear Experimental Reactor (ITER). The following provides results of a numerical simulation of a photon neutralizer for ITER NBI. This simulation has been carried out by using ZEMAX code. FIG. 4 shows a one ray trace in the trap system 10 given in FIG. 2 with a random angle from −3° to 3° in the XY plane, and −5° to 5° along the trap 10. The trajectory presented in FIG. 4 contains 4000 reflections, after which the ray remained in the trap system. In a resonance device [M Kovari, B. Crowley. Fusion Eng. Des. 2010, v. 85 p. 745-751], the storage efficiency under a mirror reflectance r2=0.9996 is about P/Pin≈500. In the case noted herein, with a lower mirror reflectance of r2=0.999, the determined storage efficiency is P / P in ≈ 1 1 - r 2 ≈ 1000 ( 11 ) Losses will tend to be associated chiefly with a large number of surfaces inside the cavity and diffraction. [J. H. Fink, Production and Neutralization of Negative Ions and Beams: 3rd Int. Symposium, Brookhaven 1983, AIP, New York, 1984, pp. 547-560] The distribution of the radiant energy flux through a horizontal plane inside the trap 10 is shown in FIG. 5, where the reflection coefficient of all surfaces is equal to 0.999 and the input radiant power is equal to 1 W. The calculated accumulated power in the cavity of the trap 10 is equal to 722 watts. Taking into account calculation losses (Zemax code monitors and evaluates such losses) the accumulated power value should be increased by 248 watts. Therefore, the storing efficiency reaches almost a maximum possible value (11). Thus, quasi-planar systems allow within the geometrical optics the creation of a confinement region with a given size. Note, that the end cone mirrors 34 and main cylindrical mirrors 32 and 20 form broken surface as shown in FIGS. 2 and 3. The broken surfaces tend to have a negative effect on the longitudinal confinement of photons because this forms an instability region (see (7)). However, the number of crossings of these borders by a ray during the photon lifetime is not large in comparison with the total number of reflections, and, thus, the photon does not have time to significantly increase longitudinal angle and leave the trap through the ends of the trap 10. Radiation Injection into Trap and Sources To pump the optic cell, photons beams with a given angular spread along and across the trap 10 can be injected through one or more small holes in one or more mirrors. For example, it is possible by using a ytterbium fiber laser (X=1070 nm, total power above 50 kW) [http://www.ipgphotonics.com/Collateral/Documents/English-US/HP Brochure.pdf]. These serial lasers have sufficient power and their emission line is near optimal. The radiation beam with necessary angular spread can be prepared from fiber laser radiation by special adiabatic conical or parabolic shapers. For example, radiation with a spread of 15° from fiber and 0300μ may be transformed to 5° and Ø1 mm, which is sufficient for the neutralizer trap 10 described herein. Efficiency of Photon Neutralization The degree of neutralization is representable as K ( P ) = 1 - exp ( σ P E 0 dV ) ( 12 ) where d is the width of the neutralization region, E0 is the photon energy, V is the velocity of the ions. P is the total accumulated power defined as P = P 0 1 - r 2 ,where P0 is the optic pumping power. The neutralization efficiency of D-flux by the laser with overall efficiency ηt may be determined as η ( P 0 ) = K ( P ) P - P - + P 0 / η l ( 13 ) where P− is the negative ion beam power. The efficiency increases with growth of D− beam power. The efficiency (13) and degree of neutralization (12) are shown in FIG. 6. This curve has been calculated for a single channel gas neutralizer in ITER injectors, in which 10 MW part is passed. Thus, in such an approach nearly 100% neutralization can be achieved with very high energetic efficiency of about 90%. For comparison, ITER neutral beam injector has a 58% neutralization [R. Hemsworth et al./Nucl. Fusion. 2009, v. 49, 045006] and correspondently the same efficiency. The overall injector efficiency while taking into account accelerator supply and transport losses has been estimated by Krylov [A. Krylov, R. S. Hemsworth. Fusion Eng. Des. 2006, v. 81, p. 2239-2248]. A preferred arrangement of an example embodiment of a negative ion-based neutral beam injector 100 is illustrated in FIGS. 7 and 8. As depicted, the injector 100 includes an ion source 110, a gate valve 120, deflecting magnets 130 for deflecting a low energy beam line, an insulator-support 140, a high energy accelerator 150, a gate valve 160, a neutralizer tube (shown schematically) 170, a separating magnet (shown schematically) 180, a gate valve 190, pumping panels 200 and 202, a vacuum tank 210 (which is part of a vacuum vessel 250 discussed below), cryosorption pumps 220, and a triplet of quadrupole lenses 230. The injector 100, as noted, comprises an ion source 110, an accelerator 150 and a neutralizer 170 to produce about a 5 MW neutral beam with energy of about 0.50 to 1.0 MeV. The ion source 110 is located inside the vacuum tank 210 and produces a 9 A negative ion beam. The vacuum tank 210 is biased to −880 kV which is relative to ground and installed on insulating supports 140 inside a larger diameter tank 240 filled with SF6 gas. The ions produced by the ion source are pre-accelerated to 120 keV before injection into the high-energy accelerator 150 by an electrostatic multi aperture grid pre-accelerator 111 in the ion source 110, which is used to extract ion beams from the plasma and accelerate to some fraction of the required beam energy. The 120 keV beam from the ion source 110 passes through a pair of deflecting magnets 130, which enable the beam to shift off axis before entering the high energy accelerator 150. The pumping panels 202 shown between the deflecting magnets 130 include a partition and cesium trap. A more detailed discussion of the negative ion-based neutral beam injector is provided in Russian Patent Application No. 2012137795 and PCT Application No. PCT/US2013/058093, which are incorporated herein by reference. The example embodiments provided herein, however, are merely intended as illustrative examples and not to be limiting in any way. In the foregoing specification, the invention has been described with reference to specific embodiments thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the invention. For example, the reader is to understand that the specific ordering and combination of process actions shown in the process flow diagrams described herein is merely illustrative, unless otherwise stated, and the invention can be performed using different or additional process actions, or a different combination or ordering of process actions. As another example, each feature of one embodiment can be mixed and matched with other features shown in other embodiments. Features and processes known to those of ordinary skill may similarly be incorporated as desired. Additionally and obviously, features may be added or subtracted as desired. Accordingly, the invention is not to be restricted except in light of the attached claims and their equivalents. |
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050376063 | abstract | Methods for making nuclear fuel compacts exhibiting low heavy metal contamination and fewer defective coatings following compact fabrication from a mixture of hardenable binder, such as petroleum pitch, and nuclear fuel particles having multiple layer fission-product-retentive coatings, with the dense outermost layer of the fission-product-retentive coating being surrounded by a protective overcoating, e.g., pyrocarbon having a density between about 1 and 1.3 g/cm.sup.3. Such particles can be pre-compacted in molds under relatively high pressures and then combined with a fluid binder which is ultimately carbonized to produce carbonaceous nuclear fuel compacts having relatively high fuel loadings. |
description | In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular techniques and applications in order to provide a thorough understanding of the present invention. However, it will be apparent to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known methods and apparatuses are omitted so as not to obscure the description of the present invention with unnecessary details. The present invention may be applied using a variety of X-ray detectors, such as detectors employing direct TFTs, indirect TFTs, CCDs equipped with scintillator, Cmos detectors, PIN-diodes and gas detectors. TFT detector elements have a minimum size of e.g. 100xc3x97100 micrometer. However, if a TFT detector element is made longer it may also be made narrower still maintaining a high fill factor. Thus, it is possible to achieve a TFT detector element being narrower than a conventional TFT and for instance 0.1-100 mm long. Thus, a detector element is achieved having a better spatial resolution than the spatial resolution normally achieved in one direction at the expense of the resolution in the other direction. FIG. 1a shows a top view of a preferred embodiment according to the invention where such elongated detector elements are used. A first array of detector elements 101 and a second array of detector elements 102 are covered with a collimator 103. Each of the arrays 101 and 102 comprise several elongated detector elements arranged, with their respective longer side, side by side, to make up an e.g. 25 cm long array of detector elements. Each of the individual detector elements can be made between 0.01 mm and 5 mm wide, e.g. 50 xcexcm. This is the distance xcex1 in FIG. 1b. Each element can then be made between 0.05 and 100 mm long, e.g. 1 mm, distance xcex2 in FIG. 1a. Even though FIGS. 1a-1c only show two arrays, more arrays may of course be incorporated. Thus, as an example, to cover a 25 cmxc3x9725 cm area using 50 xcexcm wide and 1 mm long detector elements, 250 arrays of 5000 detector elements would be needed. In the figures each detector element is schematically shown separated from its neighbours by some distance. However, this separation can be made very short, e.g. 3-5 xcexcm, so that the radiation detecting elements can be regarded, for all practical purposes, to be arranged side-by-side. The figures are thus not to scale. The collimator 103 is arranged to prevent radiation from reaching the detector elements, apart from at selected areas. Thus, the radiation source (not shown) is placed above the collimator 103, as taken in a Z-direction. The collimator 103 has a first elongated slit 104 and a second elongated slit 105. Each of the elongated slits 104 and 105 is e.g. 50 xcexcm wide and 25 cm long, thus covering the complete length of each respective array 101 and 102 in a X-direction but only a relative short distance of the length of each individual detector element in a Y-direction. The radiation reaching each detector element is thus limited in the X-direction by the width of the detector element to 50 xcexcm and limited in the Y-direction to the width of the elongated slits 104 and 105, respectively, to 50 xcexcm. Thus a spatial resolution is obtained where each pixel is 50xc3x9750 xcexcm. The X-direction, Y-direction and Z-direction are substantially orthogonal. FIG. 1b shows the arrangement in FIG. 1a taken along the line Axe2x80x94A. FIG. 1c shows the arrangement in FIG. 1a taken along the line Bxe2x80x94B. To achieve an image of the radiation the collimator 103 is moved at constant speed, or alternatively step-wise with e.g. 50 xcexcm increment in the Y-direction. The slits 104 and 105 will move over the detector element arrays 101 and 102 and let through radiation from different parts of the scanned area to the detector elements during the scanning. The radiation reaching the detector elements is continuously monitored and recorded in a computer (not shown) and an image of the radiation is assembled. As an alternative the slit 104 may pass over both the detector element arrays 101 and 102. An over sampling, or a double scanning would thus be achieved of the part of object to be imaged that are located above the original position of detecting element array 102. If, as sometimes occur in these kind of detectors, a detector element in array 102 is broken an improved imaged is obtained, since it is very unlikely that the corresponding element in detector element array 101 would also be broken. It should be clear to the man skilled in the art that in practical applications where not only two arrays are used but a multitude of arrays, substantially the complete object would be subject to over sampling. Only the part over the first array would not be subject to over sampling. It would of course also be possible to move the object to be imaged and the detecting element arrays in relation to a fixed collimator. It is also preferable to move the radiation source with the collimator, as will be discussed later. FIG. 2 shows a top view of a radiation detector according to a preferred embodiment of the invention where only one array of detector elements 201 is used and a collimator 202 comprises a corresponding elongated slit 203. If an object 204, larger than the detector, as defined by the length of the array of detecting elements in one dimension and the length of the individual detector elements in the other dimension, should be imaged, the detector can be made to move between successive scannings. FIG. 2 shows the detector in a first starting position 200a, indicated by dotted lines and in a second end position 200b, where the detector has been moved in the Y-direction in successive steps of length L, where L is the length of the detector elements in the y-direction, so as to scan the object 204. Thus the slit 203 is brought over the complete area of the object 204 and an image is recorded. That is, both the detector, comprising the array of detector elements 201, and the collimator is moved during the scan. FIG. 3 shows a side view of a preferred embodiment according to the invention comprising a first collimator 301 and a second collimator 302. The first collimator 301 has two elongated slits 303 and 304 and the second collimator has two elongated slits 305 and 306 aligned with the first collimators 301 slits 303 and 304. The elongated slits 303 and 304 are preferably arranged at the projection of incident X-ray radiation, emitted by a radiation source 310, through the slits 305 and 306. A first array of detector elements 307, of which only the first detector element is visible in this view, and a second array of detector elements 308, of which only the first detector element is visible in this view, are arranged below said first collimator 301. The first 301 and second 302 collimator are arranged at a distance to allow for an object 309, to be imaged, to be positioned there between. The primary purpose of the first collimator 301 is to prevent radiation from reaching the detector elements 307 and 308 in other positions than governed by the slits 303 and 304. The primary purpose of the second collimator 302 is to reduce the radiation dose to the object 309. This is specifically important where a living object, such as a human, is to be imaged. The radiation source 310 radiates X-rays towards the second collimator 302. The second collimator transmits photons only through the slits 305 and 306 and photons thus radiate the object 309 substantially only directly under the slits 305 and 306. The slits 303 and 304 transmit radiation towards the detector elements 307 and 308 so that a reading is obtained relating to the radiation passing through the object 309. The collimators 301 and 302 and the radiation source 310 are moved in fixed relation to each other in the Y-direction, while radiation data is continuously read by the detector elements 307 and 308, scanning the object 309. FIG. 4 shows a schematic drawing in side view of an E-arm detector apparatus according to a preferred embodiment of the invention. The E-arm comprises a first arm 401 carrying the radiation source, a second arm 402 carrying a first collimator and a third arm 403 carrying a second collimator. The first, second and third arms are fixed in relation to each other. The radiation source is arranged to radiate X-rays towards the first collimator. The E-arm is attached to a stand 404 so as to allow the E-arm to expose a pendulum movement around an axis 405, and/or a horizontal transverse movement along the x- or y-direction. An object 406 to be imaged is positioned between the first and second collimators and is fixed in relation to the stand 404. By moving the E-arm a scanning of the object 406 is achieved. A fourth arm 407 is carrying the radiation detecting elements. The fourth arm 407 may be independently movable in relation to the E-arm as required by some embodiments described herein. FIG. 5 shows a side view of a preferred embodiment according to the invention where a gas detector 501 is employed. Gas detectors are per se known and thus no detail will be given as to the specific operation of the gas detector 501. In this respect we refer to our co-pending patent applications by Francke et al. having U.S. Pat. Nos. 09/443,294, 09/698,173, 09/709,305, 09/752,722 and the Swedish patent application by Francke et al. having Swedish patent application number SE 0102097-3 all incorporated herein by reference. A first collimator 502 comprises slits 503 and 504, respectively. The first collimator 502 is primarily used for preventing excess radiation to reach an object 505 to be imaged. Slits 503 and 504 admit radiation towards to object 505 along defined openings. A second collimator 506, having two slits 507 and 508 respectively, is arranged over the gas detector 501 for admitting X-ray photons into the gas detector 501. The photons ionize the gas, resulting in that electrons, schematically indicated 509 in FIG. 6a, being released. The electrons, accelerated by a voltage 510 applied over a cathode 511 and an anode 512, is registered by two different detector elements 513 and 514, respectively. Alternatively, the voltage 510 may be strong enough to cause electron avalanche amplification during the acceleration towards the detector elements 513 and 514, respectively. The collimators 502 and 506 are moved in the Y direction in relation to the gas detector 501 to perform a scan of the object 505 and thus a 2-dimensional image is recorded. It should be clear that, even though two collimators have been shown in FIG. 5, one of the collimators 502 and 506 might be disposed with. If the amount of radiation reaching the object 505 is of no importance, the collimator 502 may be omitted. The arrangement in FIG. 6a may instead do without collimator 506 but, due to scattering of radiation, a lower resolution might be achieved. It should also be clear that, even though the detector elements 513 and 514 have been depicted as being located below the anode 512, they could equally well be positioned above the anode 512, arranged to function as the anode, in which case the anode 512 would be replaced with the detector elements, or the detector elements could even be positioned adjacent the cathode, in which case they would detect positive ions. FIG. 6 shows a preferred embodiment according to the invention having a first 601 and a second 602 array of detector elements. A collimator 603 has two slits 604 and 605 for admitting radiation towards selected parts of the detector element arrays 601 and 602. The detector elements in the two arrays of detector elements 601 and 602 are arranged with a distance xcex1 from each other, e.g. 2 mm, in X-direction. In this embodiment xcex1 is substantially larger than a distance xcex5, being the width of the detecting area in the X-direction of the detector element. In other aspect the present embodiment is similar to the embodiment described in connection with for instance FIG. 1. To obtain a complete 2-dimensional image of an object it is thus necessary to scan not only in the Y-direction by moving the collimator 603, but also to scan in the X-direction by movement of the detector arrangement, as defined by all individual detector elements, and the collimator 603 (and also possibly the radiation source) but not the object. First the collimator 603 moves in the Y-direction from its start position to its end position scanning over substantially the complete length of the detector elements. Thus, a set of image lines is obtained, however the lines are separated by the distance xcex1 in the X-direction. To obtain a complete 2-dimensional image the detector arrangement and the collimator is moved in the X-direction a distance xcex5xe2x80x2 substantially equal to the line width distance xcex5, e.g. 50 xcexcm. The collimator is again moved in the Y-direction, however this time in the opposite direction from what was the end position during the first scan, to what was the start position during the first scan, to obtain a second set of image lines in the Y-direction. The process is then repeated until the detector elements 601, 602 and the collimator 603 has moved substantially the complete distance xcex1. Thus, in summary, the collimator 603 can be said to oscillate back and fourth in the X-direction, while the detector elements 601 and 602, together with the collimator, is moved a line width distance in the X-direction, at each turning of the collimator. Even though, the FIG. 6 only shows two arrays of detector elements with 14 detector elements each, a complete detector arrangement would typically include many more arrays having many more detector elements. Typically, in practical applications, a detector arrangement, which would cover 25xc3x9725 cm, could employ detector elements having a length in Y-direction of 5 mm, and in X-direction of 50 xcexcm, being separated with 2 mm. Such an arrangement would thus have 250/5=50 arrays of detector elements, each array having 125 detector elements. Of course the collimator would have 50 slits, each slit corresponding to a respective detector array. The detector would need approximately 40 scans to complete a 2-dimensional image. If the dose administrated to the object to be imaged need to be minimal, a second collimator might be employed. It should be noted that in the description given above no specific detail has been given to the electronics involved in reading the individual radiation values by the radiation detecting elements or regarding how the assemble the images from the obtained pixel data. This is, however, well known to the man skilled in the art and the present description is therefore not burdened with these details. It will be obvious that the invention may be varied in a plurality of ways. For instance, the number of radiation detecting elements, arrays and slits may be varied without limitations. Such variations are not to be regarded as a departure from the scope of the invention. All such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the appended claims. |
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042279682 | abstract | A nuclear-reactor assembly comprising a pressure vessel for the nuclear reactor and auxiliary vessels disposed in annularly spaced relationship around the reactor pressure vessel and communicating therewith by horizontal passages in the walls between the vessels. According to the invention, the outer surface of the reactor pressure vessel, which is otherwise generally cylindrical, is formed with vertical surfaces in the region of the passages against which complementary vertical planar surfaces of the auxiliary vessels lie. The spaces between the auxiliary vessels are filled in the plane of these passages by support blocks so that the blocks together with the auxiliary vessels form a compound disk which is prestressed inwardly by a peripheral prestressing element passing around the perimeter of the disk. |
claims | 1. An energy spectrum modulation method by using an energy spectrum modulation apparatus, wherein the energy spectrum modulation apparatus comprises a rotation shaft, a first energy spectrum part and a second energy spectrum part both coupled to the shaft, and the energy spectrum modulation method comprises the steps of:modulating by the first energy spectrum modulation part a first X-ray having a first energy spectrum; andmodulating by the second energy spectrum modulation part a second X-ray having a second energy spectrum different from the first energy spectrum;whereinthe first energy spectrum modulation part includes at least one first vane, and the second energy spectrum modulation part includes at least one second vane; andthe mass thickness of the first vane is smaller than or equal to that of the second vane in the direction of the X-rays. 2. The energy spectrum modulation method of claim 1, wherein the first vane is made of material having a first Z value, the second vane is made of material having a second Z value lower than the first Z value. 3. The energy spectrum modulation method of claim 2, wherein the first vane is made of at least one of Pb, W, U and Cu. 4. The energy spectrum modulation method of claim 2, wherein the second vane is made of at least one of B, C, polyethylene and any other hydrogen-rich organic material. 5. The energy spectrum modulation method of claim 2, wherein the first vane and the second vane are arranged alternately and can rotate. 6. A method of discriminating material using X-rays having different energy levels comprising the steps of:generating alternately a first X-ray having a first energy spectrum and a second X-ray having a second energy spectrum;performing energy spectrum modulation for the first X-ray and second X-ray respectively by the energy spectrum modulation method of claim 1;utilizing the modulated first X-ray and second X-ray to interact with an inspected object;collecting the first X-ray and the second X-ray after their interaction with the inspected object to obtain a first detection value and a second detection value; anddiscriminating a material of the inspected object based on the first detection value and the second detection value;wherein the discriminating step includes generating corresponding classification functions from the first detection value and the second detection value, and determining the material of the inspected object based on the classification functions, the classification functions is fitting functions of third and fourth detection values obtained after the first X-ray and the second X-ray interact respectively with predetermined known materials having varying mass thickness. 7. The method of claim 6, wherein the detection values are the transmission intensity of the X-rays after they penetrate through the inspected object. 8. The method of claim 6, wherein the known materials are different materials which represent organic matter, light metal, inorganic matter and heavy metal respectively and whose atomic numbers are known. 9. The method of claim 6 further comprises collecting the first X-ray and the second X-ray after their interaction with the inspected object by a variable gain detector. 10. The method of claim 9, wherein the gain of the detector at the time of collecting the first X-ray is different from that at the time of collecting the second X-ray. 11. A device for discriminating material using X-rays having different energy levels comprising:a ray generation apparatus for generating alternately a first X-ray having a first energy spectrum and a second X-ray having a second energy spectrum;an energy spectrum modulation apparatus for modulating the first X-ray and the second X-ray respectively, wherein the modulated first X-ray and the modulated second X-ray interact with the inspected object;a collecting apparatus for collecting the first X-ray and the second X-ray after their interaction with the inspected object to obtain a first detection value and a second detection value; anda material discrimination apparatus for discriminating a material of the inspected object based on the first detection value and the second detection value;wherein the discriminating apparatus is further adapted to generate corresponding classification functions from the first detection value and the second detection value, and determine the material of the inspected object based on the classification functions, the classification functions are fitting functions of third and fourth detection values obtained after the first and second X-rays interact respectively with predetermined known materials having varying mass thickness. 12. The device of claim 11, wherein the detection values are the transmission intensity of the X-rays after they penetrate through the inspected object. 13. The device of claim 11, wherein the known materials are different materials which represent organic matter, light metal, inorganic matter and heavy metal respectively and whose atomic numbers are known. 14. The device of claim 11, wherein the collecting apparatus has a variable gain. 15. The device of claim 14, wherein the gain of the collecting apparatus at the time of collecting the first X-ray is different from that at the time of collecting the second X-ray. 16. An image processing method comprising the steps of:utilizing a first X-ray having a first energy spectrum and a second X-ray having a second energy spectrum to interact with an inspected object, respectively, wherein the first X-ray and the second X-ray are modulated by the energy spectrum modulation method of claim 1;collecting the first X-ray and the second X-ray after the interaction to obtain a first detection value and a second detection value;comparing the first detection value and the second detection value with a threshold value respectively to judge mass thickness information of the inspected object; andbased on the mass thickness information, combining an image obtained from the first detection value and an image obtained from the second detection value with different weighting factors;for a material having a first mass thickness, the weighting factor for the image from the first detection value is smaller than that for the image from the second detection value; for a material having a second mass thickness larger than the first mass thickness, the weighting factor for the image from the first detection value is greater than that for the image from the second detection value. 17. The image processing method of claim 16, wherein the mass thickness information is determined based on the attenuation of the X-rays from the inspected object. |
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abstract | A full-digital control rod position measurement device and a method thereof. The full-digital rod position measurement device transforms the core process of rod position measurement that is normally processed by an analog circuit or analog-to-digital mixed circuit into a digital processing. The full-digital rod position measurement device comprises an excitation power supply, an integrated interface board, and a universal signal processor. The universal signal processor processes output signals of detectors according to a preset numerical processing algorithm and outputs Gray code rod position signals. The full-digital rod position measurement device and method disclosed by the present disclosure may effectively reduce the complexity of the primary excitation circuit and the secondary measurement signal processing circuit of the detectors, and improve the operation reliability and measurement accuracy of the rod position processing equipment. |
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047612614 | claims | 1. A liquid reactor comprising: (a) a reactor vessel having a core; (b) one or more satellite tanks; (c) pump means in said satellite tank; (d) heat exchanger means in said satellite tank; (e) an upper liquid metal conduit extending between said reactor vessel and said satellite tank; (f) a lower liquid metal duct extending between said reactor vessel and satellite tanks said upper liquid metal conduit and said lower liquid metal duct being arranged to permit free circulation of liquid metal between said reactor vessel core and said satellite tank by convective flow of liquid metal; (g) a separate sealed common containment vessel around the reactor vessel, conduits and satellite tanks; (h) said satellite tank having space for a volume of liquid metal that is sufficient to dampen temperature transients resulting from abnormal operating conditions. (a) a reactor vessel having a core; (b) one or more satellite tanks; (c) an upper plenum located in the satelitte tank for receiving hot liquid metal; (d) a lower plenum located in the satellite tank for receiving cooled liquid metal, which is hydraulically interconnected with each satellite tank and the reactor vessel by a lower liquid metal conduit; (e) pump means in said satellite tank; (f) heat exhcanger means in said satellite tank; (g) an upper liquid metal conduit extending between said reactor vessel and said satellite tank; (h) a lower liquid metal duct extending between said reactor vessel and said satellite tank which with said upper liquid metal conduit hydraulically interconnects each satellite tank and the reactor vessel; said upper liquid metal conduit and said lower liquid metal duct being arrnaged to permit a free circulation of liquid metal between said reactor vessel and said satellite tank by convective flow; (i) said satellite tank having space for a volume of liquid metal that is sufficient to dampen temperature transients resulting from abnormal operating conditions and a gaseous space above the volume of liquid metal; (j) a separate sealed common containment vessel around the reactor vessel, conduits and satellite tanks; and (k) a conduit which interconnects the lower plenum of each satellite tank with the gaseous space above the upper plenum in each satellite tank. 2. A liquid metal reactor as defined in claim 1 further comprising a lower plenum in each of the satellite tanks that is hydraulically interconnected through a lower liquid metal conduit to a plenum in said reactor vessel. 3. A liquid metal reactor as defined in claim 2 further comprising a conduit which interconnects the volume of liquid metal that is in the lower plenum of the satellite tank with a gaseous space that is provided above the volume of liquid metal in said satellite tank. 4. A liquid metal reactor as defined in claim 2 further comprising pump means housed within the conduit connecting the lower plenum and the gaseous space. 5. A liquid metal reactor as defined in claim 2 further comprising means for accomodating thermal expansion of the vessels and liquid metal conduit which comprise roller means that permit horizontal movement of the satellite tank, an expansion means in the pump discharge conduit, and expansion means in the portion of the separate sealed common containment vessel that surrounds said upper liquid metal conduit and said lower liquid metal conduit. 6. A liquid metal reactor as defined in claim 5 which further comprises means to resist seismic forces said means comprising attachment means for rigidly fastening the reactor vessel to a support and seismic snubbers for attachment to the exterior of said satellite tanks. 7. A liquid metal reactor as defined in claim 2 further comprising means for accomodating thermal expansion of the vessel and conduits which comprise expansion means in the upper and lower liquid metal conduits, and a pump discharge conduit; and expansion means in the portion of the separate sealed common containment vessel that surrounds said upper liquid metal conduit and said lower liquid metal conduit. 8. A liquid metal reactor as defined in claim 7 which further comprises means to resist seismic forces which comprise attachment means for rigidly fastening the reactor vessel and satellite tank to a support. 9. A liquid metal reactor as defined in claim 2 which further comprises a plurality of cooling fins mounted on the exterior of said containment vessel. 10. A liquid metal reactor as defined by claim 1 wherein the liquid metal is selected from the group consisting of sodium and a mixture of sodium and potassium. 11. A liquid metal reactor as defined in claim 2 which further comprises a flow nozzle in a pump discharge line that is connected to said pump means. 12. A liquid metal reactor comprising: 13. A liquid metal reactor as defined in claim 12 further comprising a transverse structure across the central portion of said satellite tank to give lateral support to said pump means and said heat exchanger, said traverse structure also acting to separate the upper and lower plenum areas. 14. A liquid metal reactor as defined by claim 13 further comprising a lower plenum at the bottom of said satellite tanks and said reactor vessel, said lower plenum being sized to hold a reservoir of liquid metal. 15. A liquid metal reactor as defined by claim 14 further comprising a duct within the lower liquid duct and a plenum attached to the reactor core structure, said duct being connected to the pump means and to the plenum attached to the reactor core structure. |
summary | ||
abstract | This disclosure describes various configurations and components of a molten fuel fast or thermal nuclear reactor in which one or more primary heat exchangers are located above the reactor core of the nuclear reactor. |
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045004870 | abstract | A pressure surge attenuation system for pipes having a fluted region opposite crushable metal foam. As adapted for nuclear reactor vessels and heads, crushable metal foam is disposed to attenuate pressure surges. |
description | The present invention relates to a radiation attenuation elastomeric material, i.e. having the property of attenuating ionizing radiations and in particular those produced by powders entering the manufacturing of plutonium nuclear fuels. It also relates to the use of this elastomeric material for manufacturing protective articles against ionizing radiations. It further relates to a multilayer protective glove against ionizing radiations, at least one layer of each is formed by said elastomeric material, as well as to the use of this glove for protection against ionizing radiations emitted by powders entering the manufacturing of nuclear fuels. In a certain number of professions, it is customary to use gloves and other protective articles against ionizing radiations. This is notably the case in the nuclear industry where certain radioactive materials such as nuclear fuel powders are handled in glove boxes, i.e. sealed enclosures which are provided with specific gloves for protecting the hands, the forearms and a portion of the arms of the operator. But this is also the case in medicine where ionizing radiations are used for diagnostic and therapeutic purposes, in the plastic material industry where irradiations are used for obtaining chemical polymerization, grafting, cross-linking or degradation effects of polymers, or further in inspection and monitoring laboratories, for example for manufactured parts, where analytical techniques based on the use of ionizing radiations are used. Most radioprotection gloves presently available on the market are multilayer gloves which comprise a layer formed with an elastomer into which are dispersed fine particles of lead, in the form of metal, oxide or salt, and which is sandwiched between two layers which themselves are only formed with an elastomer. Considering the toxicity of lead and of its compounds, the manufacturing of these gloves requires heavy and costly equipment for preventing any contamination of the personnel in charge of this manufacturing. Further, removal of the waste stemming from the manufacturing of these gloves as well as that of used gloves requires specific procedures for collecting and treating them, failing which they are quite simply removed in dumps with all the harmful consequences on the environment which this may imply. Replacement of the use of lead as a radio-opaque filler with that of other metals which are also capable of attenuating ionizing radiations but which are not toxic or in any case have less toxicity has also been suggested recently. Thus, for example, U.S. Pat. No. 5,548,125 (reference [1]), recommends the use of tungsten particles dispersed in natural rubber or in ethylene-propylene-diene rubber, while patent application US 2004/0262546 (reference [2]) recommends the use of bismuth oxide particles alone or mixed with tungsten oxide, tin oxide or tin oxide/antimony oxide particles dispersed in natural rubber. It is commonly recognized that with radio-opaque fillers such as tungsten, bismuth, tin and their, oxides, for which the radiation attenuation capacity is less than that of lead, it is extremely difficult to obtain gloves which, while having effectiveness in attenuating ionizing radiations, comparable with that of lead-filled gloves, have satisfactory flexibility and therefore comfort characteristics for those wearing them. This problem, which is related to the fact that with fillers having less radiation attenuation capacity than that of lead, it is necessary, in order to obtain an elastomeric layer able to ensure comparable radioprotection with that of a layer of lead-filled elastomer, to incorporate into this elastomer a much larger amount of fillers than that required in the case of a lead-bearing filler, is discussed in detail in French patent application 2 911 991 (reference [3]). This document moreover suggests solving it by encapsulating the radio-opaque filler, in this case bismuth in the form of a trioxide, in liquid droplets which are dispersed within the elastomeric layer. The disappearance of the interface between the bismuth trioxide particles and the elastomer as well as the mobile nature of the dispersed liquid phase would suppress the stiffening effect of bismuth trioxide. Now, within the scope of their work, the Inventors noticed against all expectations that by using as a radio-opaque filler, a powder comprising bismuth trioxide, tungsten trioxide and lanthanum trioxide in suitably selected proportions, it is possible to obtain gloves, which, while having radiation attenuation properties equivalent to those of a glove comprising an elastomeric layer filled with lead oxide, have flexibility comparable with that of gloves exclusively consisting of an elastomer. It is on this observation that the present invention is based. Therefore the object of the invention is first an elastomeric material useful for manufacturing protective articles against ionizing radiations, which comprises an elastomer in which a powder of metal oxides is dispersed, and which is characterized in that the powder of metal oxides comprises from 70 to 90% by mass of bismuth trioxide, from 5 to 15% by mass of tungsten trioxide and from 5 to 15% of lanthanum trioxide. According to the invention, the respective proportions of the elastomer and of the powder of metal oxides in the material may vary to a wide extent depending on the use for which this material is intended and, notably on the radiation attenuation level and on the mechanical properties which are sought within the scope of this use. This being said, it is generally preferred that the elastomer represent from 15 to 35% by mass of the mass of the material and that the powder of metal oxides itself represent from 65 to 85% by mass of the mass of the material. For a use such as the manufacturing of gloves and notably of gloves intended for handling powders of nuclear fuels, it is preferred that the elastomer represent 25±2% by mass of the mass of the material and that the powder of metal oxides represents 75±2% by mass of the mass of the material, such proportions actually ensuring an excellent compromise between the radiation attenuation properties and the flexibility characteristics required for this type of glove. In every case, the powder of metal oxides preferably comprises 80±2% by mass of bismuth trioxide, 10±1% by mass of tungsten trioxide and 10±1% by mass of lanthanum oxide, these proportions between the different oxides having actually shown that they provide the material with optimum radiation attenuation properties. Moreover, the powder of metal oxides preferably consists of particles for which at least 90% by number have a size comprised between 1 and 100 μm and, even better at least 80% by number, have a size comprised between 1 and 50 μm and this in order to obtain a distribution of this powder as homogeneous as possible in the elastomer. According to the invention, the elastomer may be selected from very many elastomers and in particular from natural rubber, synthetic polyisoprenes, polybutadienes, polychloroprenes, chlorosulfonated polyethylenes, elastomeric polyurethanes, fluorinated elastomers (further known as fluoroelastomers), isoprene-isobutylene copolymers (further known as butyl rubbers), ethylene-propylene-diene (or EPDM) copolymers, styrene-isoprene-styrene (or SIS) block copolymers, styrene-ethylene-butylene-styrene (or SEBS) block copolymers and mixtures thereof, it being understood that the selection of the elastomer there also depends on the use for which the material is intended. Thus, for example, for the manufacturing of gloves, the elastomer is preferably selected from polychloroprenes and even better from polychloroprenes which resist to crystallization and consequently retain particularly well their flexibility over time. Such polychloroprenes are for example marketed by DuPont Performance Elastomers under the names of Neoprene® WRT and Neoprene® WD. According to the invention, the material may further comprise, depending on the use for which it is intended and on how it will be applied within the scope of this use, one or more adjuvants of the type of those conventionally used in the polymer industry such as one or several plasticizers, flexibilizing agents, antistatic agents, lubricating agents, adherence promoters or coloring agents, in which case the total mass of these adjuvants preferably does not represent more than 10% of the mass of the material. The elastomeric material according to the invention may be prepared by a method which comprises: dry mixing of the elastomer with bismuth trioxide, tungsten trioxide, lanthanum trioxide and the optional adjuvant(s) for example in an internal mixer; and transformation of the thereby obtained mixture into a material. Preferably, the mixture is transformed for example by calendering, drawing and granulation, into a material which appears as granules which may then be used for manufacturing protective articles against ionizing radiations. Therefore an object of the invention is also the use of an elastomeric material as defined earlier for manufacturing a protective article against ionizing radiations. Considering the elastomeric nature of the material according to the invention, the protective article is preferably an individual protective article such as an apron, chasuble, jacket, skirt, glove, sleeve, thyroid protection, gonad protection, eye protection band, breast protection bra or else further a surgical drape or sheet. However, this may also be a collective protective article such as for example a curtain which desirably has some flexibility, notably for storage convenience. In every case, this protective article which may comprise one or more layers consisting of the elastomeric material according to the invention, either associated or not with one or several layers in another material such as for example a textile material, may be manufactured by transforming the elastomeric material according to the invention into films, sheets or plates, by conventional molding, extruding techniques or the like, and then by cutting out parts with a suitable shape in these films, sheets or plates, and assembling these parts together and/or with other parts by sewing, welding or adhesive bonding. However, in certain cases, and notably in the case when the protective article is a glove, it is preferred: on the one hand that this protective article be a multilayer article, i.e. it comprises at least one layer in an elastomeric material according to the invention sandwiched between at least two layers in another elastomeric material; and on the other hand that it be made as a single part so that it does not exhibit any area where the attenuation of the ionizing radiations may be reduced due to the presence of a seam, a weld, an adhesive or the like. In this case, the protective article is advantageously manufactured by the conventional soaking technique which consists of forming an object by dipping a mold with a suitable shape in a succession of baths resulting from the dissolution in volatile solvents of the elastomeric materials intended to enter the composition of this object. According to the invention, the protective article against ionizing radiations is preferably a glove and more specially a glove intended for the handling of powders entering the manufacturing of nuclear fuels. Also, the object of the invention is also a multilayer glove for protection against ionizing radiations, which is characterized in that it comprises at least one layer C2 in an elastomeric material as defined earlier, inserted between at least two layers, C1 and C3 respectively, in another elastomeric material, both of these layers may either be identical with each other or not as regards the elastomeric material which makes them up and their thickness. According to the invention, the layers C1 and C3 may be in an elastomeric material selected from natural rubber, synthetic polyisoprenes, polybutadienes, polychloroprenes, chlorosulfonated polyethylenes, elastomeric polyurethanes, fluorinated elastomers, isoprene-isobutylene-copolymers, ethylene-propylene-diene copolymers, styrene-isoprene-styrene block copolymers, styrene-ethylene-butylene-styrene block copolymers, and mixtures thereof. However, it is preferred that these layers be in an elastomeric polyurethane because of the particularly interesting mechanical strength properties which this type of elastomer exhibits. Moreover, each of the layers C1,C2 and C3 may have a thickness from 50 to 1,500 μm. Advantageously, the layer C2 has a thickness from 50 to 200 μm while the layers C1 and C3 have a thickness from 150 to 300 μm. As the handling of powders of nuclear fuels is in principle carried out in glove boxes, the glove according to the invention preferably comprises a sleeve, typically with a frusto-conical shape, with the same composition as it and with a measured length from 25 to 100 cm and even better with a length from 50 to 80 cm, so as to be able to be used in a glove box. The glove according to the invention may be manufactured by a method which comprises at least: formation of the layer C1 by one or several successive soaking operations of a mold reproducing the shape of a hand and all or part of a forearm and an arm in a solution of the elastomeric material selected for forming this layer; formation of the layer C2 by one or several soaking operations of the mold in a solution of the elastomeric material according to the invention; formation of the layer C3 by one or several soaking operations of the mold in a solution of the elastomeric material selected for forming this layer;each soaking operation being immediately followed by evaporation of the solvent present on the mold; drying of the thereby formed glove and after removal of this glove from the mold, optional vulcanization. The glove according to the invention has many advantages. Indeed, it combines remarkable properties for attenuating ionizing radiations—since it has a capability of attenuating this type of radiation which may range, in lead equivalent, from 0.03 to 0.50 mm (depending on the thickness of the layer C2)—with an also remarkable flexibility since, for example, gloves comprising a layer C2 with a thickness of 100 μm (and ensuring a lead equivalent protection of 0.03 mm) have proved to have almost the same flexibility as that of gloves with comparable thickness but not containing any radio-opaque filler. It further has very satisfactory mechanical strength properties. It contains as a radio-opaque filler, a powder comprising metal oxides which do not have any toxicity known to this day for human health and the environment so that the removal of the waste stemming from its manufacture does not require any specific procedure for collection and treatment. Similarly, removal of the gloves after use does not require any specific procedure other than the one imposed by possible contamination of these gloves by radio-active materials. Finally, it is simple to make and lends itself to additional treatments such as sterilization. Because of its properties, the glove according to the invention is particularly interesting for ensuring protection against ionizing radiations emitted by powders of nuclear fuels, notably with plutonium. However, it is also possible to use this glove in all the other fields where protection against ionizing radiations may be sought such as medical imaging (radiology, scanography, . . . ), interventional radiology, nuclear medicine (scintigraphy, radiotherapy, . . . ), treatment of plastics, inspection and control of manufactured parts, etc. Other characteristics and advantages of the invention will become better apparent upon reading the additional description which follows, which relates to examples for making an elastomeric material and a glove according to the invention as well as for demonstrating radiation attenuation properties and mechanical properties of gloves according to the invention. Of course, these examples are only given as illustrations of the object of the invention and by no means are a limitation of this object. An elastomeric material according to the invention is made by mixing: 100 parts by mass of a polychloroprene (Neoprene® WRT—DuPont Performance Elastomers); 267 parts by mass of a bismuth trioxide powder consisting of particles with a size of less than 20 μm; 33 parts by mass of a lanthanum trioxide powder of optical quality, consisting of particles measuring about 25 μm; and 33 parts by mass of a tungsten trioxide powder, consisting of particles with a size of less than 250 μm;in an internal mixer adapted for the formulation of rubbers, and then submitting the resulting mixture to calendering (with which it is possible to complete homogenization of this mixture), to stretching as strips and then to granulation so as to obtain substantially cubic granules, the measured size of which is of the order of 0.5 cm. A slight amount of talc is put on the granules in order to avoid their agglomeration while waiting to be used. A glove, which is manufactured by a soaking method, comprises a layer C2 formed with an elastomeric material according to the invention and which is inserted between two layers, C1 and C3 respectively, formed with an elastomeric polyurethane. To do this, first of all two baths are prepared, one of which will allow the making of the layers C1 and C3 while the other one will allow the making of the intermediate layer C2. The first bath is prepared, as known per se in the state of the art by dissolving 100 parts by mass of an aromatic thermoplastic polyurethane crosslinked beforehand into 500 parts by mass of a ketone solvent, and then filtering and degassing the resulting solution by putting it to rest for 24 hours. The second bath is prepared by dissolving 100 parts by mass of granules such as those obtained in Example 1 hereinbefore, into 92.225 parts by mass of toluene in a propeller mixer rotating at a velocity of 1500 rpm and this for about two hours. The resulting solution is filtered by having it pass over a sieve with 160 μm meshes. Next, its viscosity (according to the AFNOR NFT 30-014 standard) and its dry extract content (by means of a halogen dessicator Mettler Toledo) are measured and if necessary, it is proceeded with adjustment of both of these parameters so that the first one is located around 180 Pa·s and the second one is of the order of 50%. The solution is then degassed by leaving it at rest for 24 hours. Once both baths are ready, it is proceeded with five successive soakings of a hand-shaped china mold in the first bath in order to form the layer C1 (which will form the internal face of the glove), and then with soaking the mold in the second bath for forming the layer C2,and then with four successive soakings of the mold in the first bath in order to form the layer C3 (which will form the external face of the glove), it being understood that each soaking operation is immediately followed by an operation consisting of evaporating the solvent present on the mould and which is carried out at room temperature under an extractor. At the end of the last solvent evaporation, the glove is left to dry several hours in a tunnel oven, the temperature of which does not exceed 100° C. and then it is removed from the mold. A glove is thereby obtained, the layer C2 of which has a measured thickness of about 100 μm and the layers C1 and C3 each have a measured thickness of about 200 μm. 3.1. Radiation Attenuation Properties Gloves as obtained in Example 2 hereinbefore were subject to tests aiming at assessing their capability of attenuating γ radiations emitted by powders entering the manufacturing of nuclear fuels. To do this, they were used on glove boxes dedicated to the handling of powders entering the manufacturing of nuclear fuels, in an exploitation representative of significant dosimetry. Thus γ radiation attenuation factors were obtained ranging from 1.5 to 4, i.e. factors equivalent to those obtained with the lead-bearing gloves customarily used on these glove boxes, which comprise a layer with a thickness of 100 μm, formed with lead oxide (litharge) particles dispersed in a polychloroprene, between two elastomeric polyurethane layers. 3.2. Mechanical Properties Gloves according to the invention (G1 to G5 hereafter), having a thickness ranging from 600 to 700 μm and comprising a layer C2,in its composition and its thickness, identical with the layer C2 of the glove made in the Example 2 above, inserted between two layers C1 and C3 in elastomeric polyurethane, were subject to tensile tests according to the AFNOR NFT 46-002 standard. Table 1 hereafter shows, for each of the tested gloves, the results obtained in terms of breaking resistance, maximum breaking force, breaking elongation and elasticity moduli at 20% and 100% of elongation during these tests as well as those obtained under the same conditions with gloves with comparable thickness but exclusively formed by elastomeric polyurethane (R1 to R5 hereafter). TABLE 1MaximumElasticityElasticityGloveBreakingbreakingBreakingmodulus at 20%modulus at 100%thicknessstrengthforceelongationelongationelongation(μm)(Mpa)(N)(%)(Mpa)(Mpa)GlovesG160031.7766711.11.9according toG260032.6786661.01.7the inventionG368026.0716511.01.6G470025.1706691.11.7G560030.1728191.01.8Average60029.1736951.01.7Gloves inR148046.8906761.22.0elastomericR252044.4925901.22.2polyurethaneR367030.5825771.01.5R471027.8796300.91.5R545045.7827821.42.1Average57039.0856511.11.9 This table shows that the elasticity moduli at 20% and 100% of elongation, and therefore the flexibility of the gloves according to the invention, are equivalent to those of gloves in elastomeric polyurethane, with comparable thickness but without any layer loaded with metals or metal oxides. It also shows that the mechanical strength properties of the gloves according to the invention are also very satisfactory. Cited References [1] U.S. Pat. No. 5,548,125 [2] Patent Application US 2004/0262546 [3] Patent Application FR 2 911 991 |
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061920959 | claims | 1. A process of preparing a .sup.133 Xe radioactive stent to be placed within a blood vessel for preventing restenosis of the blood vessel by retarding the growth of smooth muscles by means of .beta.-rays and internal conversion electrons emitted from .sup.133 Xe, the process comprising: generating a gaseous nuclear fission product of .sup.133 Xe by nuclear fission in a .sup.235 U target in fuel rods in a nuclear reactor upon irradiation of .sup.235 U with neutrons; flowing the gaseous .sup.133 Xe fission product into a Xe purifier; supplying .sup.133 Xe from the Xe purifier into an ion source to ionize the .sup.133 Xe and yield an ion beam of .sup.133 Xe; and introducing the ion beam into an irradiating unit to irradiate stents positioned on a vertically moveable rotating table and to uniformly inject .sup.133 Xe into the surface of the stents. |
06297419& | abstract | This disclosure sets forth a method for processing metal waste incorporating substantial zirconium as exemplified by nuclear fuel rods which include enriched uranium and other nuclear products. This process contemplates conversion of the zirconium and other constituents into oxides by mixing with an acid, subsequently forming a solution or a gel which is either dried or frozen, thereby yielding a green shaped body. The green body is thereafter sintered to form a dimensionally and structurally stable monolith for disposal. |
042726824 | claims | 1. A machine for ion milling a specimen comprising: a main evacuated chamber having an upper port and a lower port; ion milling means for ion milling of a specimen disposed in said main evacuated chamber; a secondary chamber in communication with said main chamber through its upper port for specimen viewing and exchange; specimen positioning means extending through said lower port of said main chamber for vertically moving the specimen between a first position in said main evacuated chamber, where ion thinning is accomplished, and a second position in said secondary chamber, where the specimen can be viewed and exchanged; means for sealing said main chamber at its lower port; and sealing means for providing a vacuum seal between said main chamber and said secondary chamber when said specimen positioning means is in the second position. said secondary chamber is removable from said main chamber; and, said secondary chamber is held to said main chamber by atmospheric pressure when said main chamber and said secondary chamber are evacuated. a transparent outer portion disposed so the specimen can be viewed when said specimen positioning means is in the second position. vacuum valve means for connecting a vacuum to said secondary chamber; and atmospheric valve means for connecting said secondary chamber to atmosphere. drive means for rotating said specimen positioning means when said specimen positioning means is in the first position. said specimen positioning means comprises an elongated piston extending into said main evacuated chamber and being movable along its longitudinal axis; said sealing means at said lower port of said main chamber includes a seal around said elongated piston where it extends into said main evacuated chamber; and, said drive means comprises: a positioning cylinder disposed around a portion of said elongated piston outside of said main evacuated chamber; a sealing plate providing a seal between said elongated piston and said positioning cylinder; and the means for admitting or exhausting pressurized gas from the positioning cylinder for causing movement of said piston along its longitudinal axis. a main chamber wherein ion thinning of the specimen is accomplished under vacuum; a specimen elevating means for moving the specimen between a lowered position where ion thinning is accomplished and a raised position where the specimen can be viewed; said specimen elevating means comprising, a secondary chamber for receiving said specimen when said specimen elevating means is in its raised position; and sealing means for sealing said secondary chamber from said main chamber when said specimen elevating means is in said raised position. drive means for rotating said piston when said specimen elevating means is in its lowered position. said specimen elevating means moves vertically and comprises a holder platform disposed for horizontally supporting a specimen so that the specimen can be held in place by the force of gravity. a main evacuated chamber having an upper port and a lower port; ion milling means for milling a specimen disposed in said main evacuated chamber; a secondary chamber in communication with said main chamber through its upper port; specimen support means extending into said main evacuated chamber through its lower port for supporting a specimen and being movable between a first position wherein said specimen is in said main chamber in position for ion milling and a second position wherein said specimen is in the secondary chamber; means for sealing said main chamber where said specimen support means extends through said lower port of said main chamber; sealing means for sealing said secondary chamber from said main chamber when said specimen support means moves the specimen into the secondary chamber; and drive means for rotating the specimen when said specimen support means is in the first position. atmospheric biasing means for biasing said specimen support means to the second position by atmospheric pressure; pressurized gas biasing means for biasing said specimen support means to the first position by utilizing pressurized gas; and release means for controllably releasing the pressurized gas from said pressurized gas biasing means to permit said specimen support means to move to the second position under the influence of atmospheric pressure. a specimen inspection chamber in communication with said main chamber; means for supporting said specimen within said main chamber in a first position during said ion milling and for transporting said specimen to a second position within said inspection chamber; means for sealing said main chamber from said inspection chamber when said specimen supporting and transporting means moves said specimen into said second position; means for biasing said specimen supporting and transporting means toward said second position by the selected application thereto of atmospheric pressure; and means for overcoming said biasing means by the selected application of superatmospheric pressure to said specimen supporting and transporting means to urge it into said first specimen position. said specimen inspection chamber is releasably connected to said main chamber, when said specimen is in said second position, by the selective application of atmospheric or subatmospheric pressure to the interior of said inspection chamber. a main chamber wherein ion thinning is accomplished under vacuum; a specimen elevating means for moving the specimen between a lowered position where ion thinning is accomplished and a raised position where the specimen can be exchanged; said specimen elevating means comprising: a secondary chamber for housing said specimen when said specimen elevating means is in its raised position; and sealing means for sealing said secondary chamber from said main chamber when said specimen elevating means is in said raised position. 2. A machine as claimed in claim 1 wherein: 3. A machine as claimed in claim 2 wherein said secondary chamber comprises: 4. A machine as claimed in claim 1 which further comprises: 5. A machine as claimed in claim 1 which further comprises: 6. A machine as claimed in claim 5 wherein: 7. A machine as claimed in claim 6 wherein said specimen positioning means further comprises: 8. A machine as claimed in claim 7 wherein said piston is oriented vertically. 9. An ion milling machine for ion thinning a specimen comprising: 10. An ion milling machine as claimed in claim 9 comprising: 11. An ion milling machine as claimed in claim 10 comprising: 12. An ion milling machine as claimed in claim 9 wherein: 13. An ion milling machine comprising: 14. An ion milling machine as claimed in claim 13 comprising: 15. In an ion milling machine having a main chamber in which ion milling of a specimen disposed therein is carried out under subatmospheric pressure, the improvement comprising: 16. The improvement recited in claim 15 wherein: 17. An ion milling machine for ion thinning a specimen comprising: |
abstract | Radioactive waste may be stored in storage containers that are suitable for long-term disposal, but do not provide adequate shielding. By assembling an overpack from metal plates, the metal plates each being substantially flat, and the overpack providing sufficient shielding for the radioactive waste, and enclosing the storage container that contains radioactive waste in the overpack, the storage container can then be stored safely in a weatherproof enclosure. The enclosure does not need to provide radiation shielding. The plates can be stored as a flat-pack, and assembled into the overpack when required. |
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claims | 1. A minute sample processing and observation apparatus comprising:a first sample stage on which a sample is placed;a probe for taking out a minute sample from the sample;a second sample stage on which the minute sample is fixed;a second sample stage controller that controls an angle of the second sample stage;a sample chamber in which the first sample stage, the probe and the second sample stage are arranged;a focused ion beam optical system for applying an ion beam to the sample placed on the first sample stage and the minute sample fixed on the second sample stage;an electron beam optical system for applying an electron beam to the minute sample fixed on the second sample stage;wherein the focused ion beam optical system applies the ion beam to the sample placed on the first sample stage for extracting the minute sample from the sample, and the probe supports the minute sample;the focused ion beam optical system and the electron beam optical system are arranged within the sample chamber;the minute sample supported by the probe is fixed to the second sample stage;the focused ion beam optical system applies the ion beam to the minute sample fixed on the second sample stage for creating a desired observation section;the second sample stage controller controls the angle of the second sample stage so as to locate an observation section at substantially vertical to the electron beam;the electron beam optical system applies the electron beam to the minute sample for observing the observation section, andobservation of an inner section of the sample can be carried out with the sample in the sample chamber, and the sample chamber having a vacuum atmosphere. 2. A minute sample processing and observation apparatus according to claim 1, wherein the sample is a semiconductor device. 3. A minute sample processing and observation apparatus according to claim 1, wherein the sample is a wafer. 4. A minute sample processing and observation apparatus according to claim 1, wherein the minute sample extracted from the sample is a pentahedron. 5. A minute sample processing and observation apparatus according to claim 1, wherein the minute sample extracted from the sample is a tetrahedron. |
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claims | 1. A method of irradiating a target tissue in a patient, which method comprises:positioning the patient on a patient support system so that the target tissue in the patient is within irradiating distance of multiple beams of radiation, wherein (a) each beam, which is from a different source or a single arcing source, is from a different direction and has a central axis, (b) the central axes of the multiple beams are focused on a fixed point in the target tissue, and (c) each beam rotates around its own central axis and around the fixed point of focus, andcontinuously moving the patient support system relative to the fixed point of focus of the multiple beams of radiation and, coordinately with movement of the patient support system, continuously rotating at least one beam of radiation around the fixed point of focus in the target tissue, which comprises and/or is adjacent to a non-target tissue, so that the fixed point of focus is constantly moving within the target tissue, while simultaneously and/or sequentially irradiating the target tissue,whereupon the target tissue in the patient is irradiated in a pattern created by the coordinated continuous movement of the patient support system and the continuous rotation of at least one beam of radiation around the fixed point of focus in the target tissue. 2. The method of claim 1, wherein the beam of radiation has a D-shaped cross-section. 3. The method of claim 2, wherein the straight edge of the D-shaped cross-section of the beam of radiation is placed tangentially to the boundary of the target tissue and the non-target tissue, as the beam of radiation is rotated. 4. A collimator, which (i) shapes a beam of radiation to have a D-shaped cross-section, (ii) maintains the central axis of the beam of radiation on or adjacent to the straight edge of the D-shaped cross-section of the beam of radiation, and (iii) fully rotates the beam of radiation in either direction about the beam axis during irradiation, such that the straight edge of the D-shaped cross-section of the beam of radiation faces any direction during irradiation. 5. A method of making the collimator of claim 4, which method comprises joining half of a circular (cross-section) collimator with a cone-shaped tunnel with half of a rectangular (cross-section) collimator with a pyramid-shaped tunnel, where the circular and the rectangular collimators have the same divergence, whereupon the collimator is made. 6. A system for irradiating a target tissue in a patient comprising:(i) a patient support system, which comprises (a) a table or a couch, either of which is optionally padded, (b) one or more motors, each of which drives movement of the table or the couch in the direction of a separate axis, (c) optionally, a base, in which case the one or more motors are housed in the base, and (d) a computerized control system, which controls the continuous movement of the patient support system;(ii) multiple beams of radiation, wherein (a) each beam, which is from a different source or a single arcing source, is from a different direction and has a central axis, (b) the central axes of the multiple beams are focused on a fixed point in the target tissue, and (c) each beam rotates around its own central axis and around the fixed point of focus;(iii) at least one collimator, wherein each collimator is operably aligned with one rotatable source of a beam of radiation; and(iv) a central control unit, which executes a patient treatment plan including coordinating continuous rotation of at least one beam of radiation around its own central axis, continuous rotation of at least one beam of radiation around the fixed point of focus, and continuous movement of a patient support system relative to the fixed point of focus of the multiple beams of radiation. 7. The system of claim 6, wherein the at least one collimator (a) shapes the beam of radiation to have a D-shaped cross-section, (b) maintains the central axis of the beam of radiation on or adjacent to the straight edge of the D-shaped cross-section of the beam of radiation, and (c) fully rotates the D-shaped cross-section of the beam of radiation in either direction, such that the straight edge of the D-shaped cross-section of the beam of radiation faces any direction during irradiation. 8. A method of planning irradiation of a target tissue in a patient with the system of claim 6, which method comprises:(i) determining the volume and the surface contour of the target tissue to be irradiated and, if present, the volume and the surface contour of a non-target tissue located wholly within the target tissue and/or the surface contour and, optionally, the volume of a non-target tissue located partially within the target tissue,(ii) setting the radiation dose to be delivered to the target and limiting the radiation dose to the non-target tissue;(iii) assigning control points to the surface contours identified in (i),(iv) determining the angle of the beam of radiation, the orientation of the collimator, and the position of the patient support system at each control point,(v) assigning “wild card” points within the volume of the target tissue with the proviso that a “wild card” point is not assigned within the volume of any non-target tissue that is located wholly or partially within the target tissue,(vi) determining the path of motion when all control points and one or more “wild card” points, are connected and optimizing the weighting of each control point of radiation so as to provide a dose pattern of radiation within the target tissue and a sharp drop-off away from the boundary between the target tissue and any non-target tissue, and(vii) checking the resulting radiation dose distribution against a desired radiation dose distribution and adjusting the path of motion and the weightings of control points accordingly and, if needed, adding more control points,whereupon irradiation of a target tissue in a patient is planned. 9. The method of claim 8, wherein the at least one collimator of the system (a) shapes the beam of radiation to have a D-shaped cross-section, (b) maintains the central axis of the beam of radiation on or adjacent to the straight edge of the D-shaped cross-section of the beam of radiation, and (c) fully rotates the D-shaped cross-section of the beam of radiation in either direction, such that the straight edge of the D-shaped cross-section of the beam of radiation faces any direction during irradiation. 10. The method of claim 9, wherein the straight edge of the D-shaped cross-section of the beam of radiation is maintained tangentially to the surface contour identified in (i). |
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summary | ||
051397323 | description | DESCRIPTION OF PREFERRED EMBODIMENT FIG. 1 shows a pressurizer of a pressurized-water nuclear reactor 1 comprising a casing 2 consisting of a cylindrical barrel which is arranged with its axis vertical and which is closed at its upper end by means of a domed bottom 2a and at its lower end by means of a domed bottom 2b. Heating rods 3 pass through the lower domed bottom 2b and are held in a vertical arrangement in the lower part of the casing 2 by a lower spacer plate 4a and by an upper spacer plate 4b. A connection piece 5 likewise passes through the domed bottom 2b in the central part of the latter and makes it possible to connect the inner volume of the pressurizer to the primary circuit of the nuclear reactor. The parts of the heating rods 3 projecting relative to the lower domed bottom 2b are arranged inside a supporting skirt 6 forming the extension of the barrel 2 and making it possible to fasten the pressurizer in the structure of the nuclear reactor. An inspection port or manhole 7 passes through the upper domed bottom 2a of the casing 2 of the pressurizer, a connection piece 8 making it possible to connect the spray piping of the pressurizer and connection pieces 9 and 10 making it possible respectively to connect a pressure-reducing piping and mount a safety valve. FIG. 2 shows the lower part of the pressurizer 1, in which are arranged the heating rods 3 passing through the lower domed bottom 2a of the casing 2 inside passage sleeves 12 fastened sealingly to the bottom 2a. Each of the rods 3 is connected to a connection sleeve fastened to a corresponding passage sleeve 12 by means of a weld 13. The heating rods 3 are engaged into orifices passing through the lower spacer plate 4a and upper spacer plate 4b making it possible to hold the rods 3 in a vertical arrangement. The spacer plates 4a and 4b are fastened, on their periphery, to supporting right-angle brackets 14a and 14b fixed to the inner wall of the pressurizer casing 2. The disc-shaped plate 4a has a central orifice of small diameter and an outside diameter substantially smaller than the inside diameter of the pressurizer casing, so that peripheral space of considerable width is provided round the outer edge of the plate 4a. The upper plate 4b has a central orifice of large diameter and an outside diameter which is only slightly smaller than the inside diameter of the pressurizer casing 2, the space provided round the plate 4b being of small width. The heating rods are connected, at their end located outside the pressurizer casing, to means for feeding electrical current to electrical resistors arranged inside the tubular casing of the rod. An electrical connection device 15 has been shown on the end part of the rod 3b illustrated in FIG. 2. The rod 3a has been shown in a configuration allowing it to be extracted and replaced. The electrical connection device 15 is removed and the sleeve is cut along a cutting line 16 located above the weld joint 13. The rod 3a illustrated in FIG. 2 does not have any deformation, and it is therefore possible to carry out its extraction by exerting an axial pull on the end of the connection sleeve, all the operations necessary for the extraction being conducted from outside the steam generator. The heating rod 3c illustrated in FIG. 2, which has deformations, particularly a bulge 17 above the lower spacer plate 4a, cannot be extracted simply by pulling on its lower end located outside the pressurizer casing. To carry out the replacement of a deformed rod, such as the rod 3c, it is necessary to put the process according to the invention into practice. A first cut of the heating rod 3c is made in a zone 18 located just above the spacer plate 4a and below the bulge 17. A second cut 19 is made just below the upper spacer plate 4b. The heating rod is thus separated into three successive portions 20a, 20b and 20c which can be extracted separately from the pressurizer casing 2. The portion 20a can be extracted from the pressurizer from outside the casing 2 by pulling on the end of the rod 3c located outside the casing 2. The portions 20b and 20c are picked up inside the pressurizer casing 2 and extracted by way of the manhole 7. The replacement of the heating rod 3c can be carried out by introducing a new rod from outside the pressurizer and via its lower end, as in prior art replacement processes. The heating rod 3d illustrated in FIG. 3 has a deformation consisting of a bulge 21 located just above the corresponding passage sleeve 12. The presence of the bulge 21 prevents the rod 3d from being extracted by cutting its connection sleeve and by pulling on its end located outside the pressurizer casing. The extraction of the rod 3d makes it necessary to put the process according to the invention into practice. A first cut of the rod 3d is made, inside the pressurizer casing, along the cutting line 22 above the sleeve 12 and below the bulge 21. A second cut is made along the cutting line 23 located below the lower spacer plate 4a. The upper portion 24a of the rod 3d and the lower portion 24b located above the sleeve 12 can be extracted from the casing 2 by way of the manhole 7. The part of the heating rod 3d remaining in the sleeve 12 can be extracted from the sleeve from outside the pressurizer simply by pulling on the end of the heating rod projecting from the pressurizer casing. FIGS. 4, 5, 6 and 7 illustrate remotely controlled devices making it possible to carry out the cutting of the deformed heating rods inside the pressurizer and to extract the rod portions obtained after cutting. A first type of cutting device consists of a robot, such as 25 or 25', illustrated in FIGS. 4 and 5 and making it possible to carry out the cutting of the heating rods just above or just below the spacer plates 4a and 4b. The device 25 makes it possible to carry out the cutting of heating rods above the spacer plate 4a and the device 25' makes it possible to carry out the cutting of heating rods below the upper plate 4b. The devices 25 and 25' comprise means allowing the remote control of their movement between two concentric rows of heating rods 3. As can be seen in FIG. 5, the spacer plates, for example the disc-shaped lower spacer plate 4a, comprise concentric rows of orifices each intended for receiving a heating rod 3. Between these concentric rows of orifices, water passage orifices 27 pass through the spacer plate, which orifices are arranged in concentric circles and uniformly spaced in the circumferential direction. The device 25 forming a robot capable of moving independently between the rows of rods comprises a central part 28 constituting the support of the machining turret 30 and two lateral slides 31a and 31b mounted slidably on the central part 28 of the device 25 and associated with remote-controlled driving means making it possible to move the slides 31a and 31b in the longitudinal direction of the end parts of the central element 28, these misaligned end parts forming an angle slightly less than 180.degree. relative to one another. The central element 28 carries two retractable grasping fingers 32, 32', and slides 31a and 31b carry a retractable grasping finger 33a, 33b respectively. The grasping fingers 32, 32' and 33a, 33b can be controlled remotely in order to ensure that they are introduced into and clamped in a water passage orifice 27 or, on the contrary, that they are retracted onto the outside of a water passage 27 in which they are engaged and clamped. When the device 25 is in engagement, by means of the fingers 32 and 32' with two successive water passage orifices located between two rows of heating rods 3, the cutting tool carried by the working turret 30 is capable of carrying out the cutting of a heating rod 3 located in one of the rows between which the robotized cutting device 25 is placed. To move the device 25 in the direction of a heating rod to be cut which is located in one of the rows between which the device 25 is placed, the fingers 32 and 32' and the finger 33a or 33b of the slide 31a or 31b located opposite the direction of advance are put into their retracted position. The general movement of the central element 28 and of the slide, the finger of which is in the retracted position, is brought about by controlling the driving means of the slide, the finger of which is in the grasping position inside a water passage orifice 27. The movement is executed over a distance corresponding to the space between two water passage orifices 27. The grasping fingers arranged at the rear of the movable assembly take their place opposite two water passage orifices 27 by advancing one step. These fingers are engaged into and clamped in the corresponding water passage orifices, and the grasping finger arranged on the slide located at the front of the device 25 is put into the retracted position. This slide located at the front of the device 25 is moved one step, in such a way that its grasping finger comes into engagement inside the next water passage orifice in the direction of movement along the water passage line. The next movement step can then be executed. The device 25 can thus be moved in successive steps in the circumferential direction of the water passage line 27 between two rows of heating rods 3. This circumferential movement is made possible by the inclination of the longitudinal direction of the end parts of the central element 28. The device 25 carries inspection means, such as a miniaturized video camera, making it possible to identify the heating rods 3 having deformations. The movement of the robotized cutting device 25 and its placement in the operating position can thus be controlled remotely. A robotized cutting device of a second type is illustrated in FIGS. 4 and 6. This device 35 is capable of moving between the rows of heating rods 3 by bearing on the upper ends of the passage sleeves 12 and on the heating rods. As can be seen in FIG. 6, the general structure of the device 35 is substantially identical to the general structure of the device 25 which has just been described. The device 35 comprises a central element and two slides, the central element carrying a working turret 36 and two grasping forks 37 and 37', and the slides each carrying a grasping fork 38a, 38b, respectively. The grasping forks 37, 37' and 38a, 38b can be controlled remotely in order to assume the grasping position on the heating rods 3, just above the sleeves 12 ensuring the support of the cutting device 35. The slides of the device 35 are mounted movably on the central element, and their movement in the longitudinal direction can be controlled remotely in an amount corresponding to the distance separating two heating rods 3 located on one row. The cutting device 35 can be moved and put into the operating position in a way similar to that described previously as regards the with regard to device 25. As can be seen in FIGS. 5 and 6, the heating rods 3 are not arranged over the entire annular zone defined by the spacer plates 4a and 4b. A zone 40 devoid of heating rods occupies a particular length in the circumferential direction of the plates 4a and 4b. The zone 40 without heating rods makes it possible to carry out the introduction and positioning of the cutting devices 25 and 35 between any two rows of heating rods, as will be explained later. FIG. 7 illustrates all the means making it possible to place the robotized devices 25 and 35 at the entrance of an aisle located between two rows of rods 3 of the pressurizer. These means comprise a vertical structure 41 which rests on the bottom of the pressurizer and on which a transfer rail 42 is mounted for rotation about a vertical axis and in a transverse arrangement by means of bearings 42'. The ramps 43 and 44 for supporting and guiding the devices 25 and 35 are mounted in an articulated manner about a horizontal axis on the rail 42 in the region of the spacer plates 4a and 4b, respectively. The ramps 43 and 44 can be placed by a remote-controlled device into a horizontal position, in which these ramps are in the extension of the spacer plates 4a and 4b. The ramps 43 and 44 have a row of orifices, the arrangement of which corresponds to the position of the water passage orifices of the spacer plates 4a and 4b, thereby providing geometrical continuity. The rail 42 likewise carries a pivoting ramp 45 located in the region of the upper end of the passage sleeves 12 of the heating rods. The ramp, which has dummy heating rods, also provides geometrical continuity. The robotized cutting devices 25, 25' and 35 can be moved in the vertical direction by means of a bundle of cables for the suspension and feed of the corresponding mechanism connected to a lifting means carried by the transfer rail 42. The cable bundle 46 makes it possible to place the robotized cutting mechanism 25 on the upper or lower surface of the ramp 43, depending on the level at which action is to be taken by the device 25. In the same way, the bundle 46' makes it possible to place the robotized cutting device 25' on the upper or lower surface of the ramp 44. The bundle 47 makes it possible to place the robotized cutting device 35 on the upper surface of the ramp 45. The positioning of the robotized device 25, 25' or 35 between two particular rows of heating rods is carried out in the region of the zone 40 of the pressurizer in which there are no heating rods. The positioning of the robotized devices is ensured by means of a radial movement, as indicated diagrammatically by the arrows 48, 49 and 50. The radial movement of the robotized mechanisms for placing them inside the space 40 can be ensured by the means for moving these mechanism inside the rows of rods. In this case, it is necessary to cause the robotized cutting mechanism to execute a rotation of 90.degree., in order to align it with circumferential space between two rows of heating rods. It is also possible to place the robotized mechanism in its circumferential position on the corresponding ramp if the device has means of movement in two mutally perpendicular directions. Monitoring by video camera makes it possible to identify the rows of heating rods between which the cutting device is to be introduced. The robotized cutting mechanisms comprise, in addition to their working turret, a means for grasping the heating rods, thus making it possible to carry out the extraction of the portions of heating rods after cutting, by using the handling and lifting means of the robotized mechanisms. The robotized mechanisms are introduced into the pressurizer by way of the central orifices of the spacer plates. To carry out this introduction and this positioning of the robotized devices, it may be necessary to rebore the lower spacer plate. The positioning of the robotized devices and the extraction of the portions of heating rods could also be carried out by passage through the free space located on the periphery of the spacer plates. At all events, the process and device according to the invention make it possible to carry out the extraction of heating rods having deformations in the region of the spacer plates or above the passage sleeves of these rods. This extraction is carried out remotely and requires no manual action inside the pressurizer casing, thus avoiding exposing operators to an irradiated environment. The cutting of the heating rods inside the pressurizer casing can be performed by remote controlled cutting mechanisms other than those described. These mechanisms can comprise means of movement between the rows of heating rods other than those described. Likewise, the means for positioning the robotized mechanisms can be different from those described. The process according to the invention can also be carried out by using sequences for the cutting and extraction of portions of the heating rods which are different from those described. |
043022898 | abstract | A method of refueling a nuclear reactor having a core containing a plurality of fuel rod bundles which are built up from a plurality of fuel rods includes replacing at least one burnt up fuel rod bundle with a fuel rod bundle which is at least partly composed of fuel rods from other fuel rod bundles burnt up in the reactor, the mean content of fissile material in the fuel rod bundle thus composed being higher than the mean content of fissile material in the fuel rod bundle which is replaced by the composed fuel rod bundle. |
abstract | The invention provides an actuator apparatus and method where a source provides electrons to a target material wherein electrical work is performed. A beta emission process comprises a source material emitting electrons which are then captured by a target material. The actuator's source vanes rotate within an electric field between the target chutes' walls, generating torque. The principal providing torque and power is the change in energy as a vane gets closer to the outer walls. During the release and capture process, electrical work is performed which, in turn, is transferred into mechanical work in the form of rotation of the rotor. Specific applications include a radioisotope fueled rotary actuator for micro and nano air vehicles employed as the main form of propulsion. |
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06188748& | abstract | A contour collimator has a plurality of plate-shaped diaphragm elements movably arranged with respect to each other in a guiding block to form a contour diaphragm for a radiation beam emitted by a radiation source towards the collimator, and at least one drive for moving the diaphragm elements. A drive is associated with each diaphragm element with the drives of a group of diaphragm elements being substantially adjacent, and a driving transmission arranged between each drive and the associated diaphragm element. |
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claims | 1. For use with an ion implanter having an ion source and an implantation chamber; apparatus comprising:a) beam forming structure that scans ions from side to side to produce a thin ion beam moving into an ion implantation chamber;b) a workpiece support for positioning a workpiece within the implantation chamber;c) a drive for moving the workpiece support back and forth through the thin ion beam to effect controlled ion beam processing of said workpiece; andd) a control including:i) a first control output coupled to the beam forming structure that limits an extent of side to side scanning to reduce a width of the ion beam to a width less than a width of the workpiece thereby limiting ion beam processing of the workpiece to a specified region of the workpiece; andii) a second control output coupled to the drive to control back and forth movement of the workpiece to a specified amount; said first and second control outputs causing the ion beam to impact less than an entire surface of the workpiece. 2. The apparatus of claim 1 wherein the second control output from said control causes the drive to move the support back and forth at a non uniform rate. 3. The apparatus of claim 1 wherein the workpiece is a generally circular workpiece and wherein the control limits a width of the ion beam to intercept approximately one half of the workpiece and further limits back and forth movement of the support to cause said beam to implant ions into a selected single quadrant of said generally circular workpiece during a scan cycle. 4. The apparatus of claim 3 wherein the control performs additional scan cycles for ion beam processing other quadrants of said workpiece. 5. The apparatus of claim 4 wherein a dose is adjusted to have different values in different quadrants of said wafer. 6. The apparatus of claim 5 wherein the dose is controlled by adjusting a back and forth workpiece speed. 7. The apparatus of claim 1 additionally comprising two current sensors spaced on opposite sides of said workpiece support for monitoring current passing through the implantation chamber in the region of the workpiece. 8. The apparatus of claim 1 additionally comprising a tilt drive for adjusting an angle at which the ions that make up the beam strike a workpiece treatment surface. 9. The apparatus of claim 1 additionally comprising a twist drive for rotating the workpiece about an axis to perform treatment of a specified portion of the workpiece. 10. For use with an ion implanter having a source and an implantation chamber; apparatus comprising:a) structure including one or more scan electrodes that produces a thin beam of ions moving into an ion implantation chamber by deflecting ions in a scanning side to side deflection pattern;b) a workpiece support for positioning a workpiece within the implantation chamber;c) a drive for moving the workpiece support back and forth through the thin beam of ions to effect controlled beam processing of said workpiece; andd) a control including a control output coupled to the scan electrodes to vary a dose received by the workpiece by changing a delay period at ends of the back and forth deflection pattern during movement of the workpiece through the thin beam of ions. 11. The apparatus of claim 10 wherein the control causes the drive to move the support back and forth at a non uniform rate. 12. The apparatus of claim 10 additionally comprising two current sensors spaced on opposite sides of said workpiece support for monitoring current passing through the implantation chamber in the region of the workpiece. 13. For use with an ion implanter having an ion source and an implantation chamber; apparatus comprising:a) beam forming structure that produces a thin ion beam moving into an ion implantation chamber;b) a workpiece support for positioning a workpiece within the implantation chamber;c) a drive for moving the workpiece support back and forth through the thin ion beam to effect controlled beam treatment of said workpiece; andd) a control including:i) a first control output coupled to the beam forming structure that limits a width of the ion beam to less than a maximum amount and thereby limits ion processing of the workpiece to a specified region of the workpiece; andii) a second control output coupled to the drive to control back and forth movement of the workpiece support to a specified amount so that a controlled portion of said workpiece having a width less than an entire width of the workpiece is treated by the thin beam of ions during the back and forth movement of the workpiece. |
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description | This application is the U.S. National Phase under 35 U.S.C. §371 of International Application No. PCT/JP2009/062928, filed on Jul. 10, 2009, which in turn claims the benefit of Japanese Application No. 2008-252130, filed on Sep. 30, 2008, the disclosures of which Applications are incorporated by reference herein. The present invention relates to an electron microscope. For example, the present invention relates to a phase adjuster for providing an arbitrary phase adjusting mechanism in terms of electron beam optics. In addition, for example, the present invention relates to a spherical aberration of the electron microscope. In addition, for example, the present invention relates to a transmission electron microscope for forming an enlarged image of a sample to be observed as faithfully to its original structure as possible. A transmission electron microscope is an apparatus which enables the observation of an atomic-scale structure, and fulfills its function in various fields. However, an image which can be observed using the transmission electron microscope is an image formed by the interference between electron beams, and hence the observed image cannot be interpreted as it is. Therefore, simulation and the like are performed, and observation results and calculation results are compared with each other, to thereby analyze the original structure of an observation sample. JP Patent Publication (Kokai) No. 2006-162805 A discloses a phase difference electron microscope. In addition, JP Patent Publication (Kokai) No. 2006-318939 A discloses a spherical aberration corrector. Patent Literature 1: JP Patent Publication (Kokai) No. 2006-162805 A Patent Literature 2: JP Patent Publication (Kokai) No. 2006-318939 A Non Patent Literature 1: R. Danev and K. Nagayama, Ultramicroscopy, 88 (2001) 243. The inventors of the present application intensively studied the reason why results observed using a transmission electron microscope are different from the original structure of a sample. As a result, the following findings were obtained. Hereinafter, the reason why the results observed using the transmission electron microscope are different from the original structure of the sample is described by describing the principle of image formation by the transmission electron microscope. An image observed using the transmission electron microscope is formed by the contrast between light and dark. The contrast observed using the transmission electron microscope is roughly categorized into a scattering contrast and a phase contrast. For the scattering contrast, electrons scattered by the sample are cut for image formation by an objective diaphragm which is disposed on the back focal plane of an objective lens and transmits therethrough only a transmission wave, whereby an image is obtained. The scattering contrast refers to a contrast obtained by scattering as its name suggests. On the other hand, the phase contrast refers to a contrast obtained by the interference between electron beams. In a broader interpretation, the phase contrast refers to a contrast generated by the interference between all the electron waves which contribute to the image formation by using an appropriate objective diaphragm, of electron waves generated on the lower surface of the sample. Here, it is assumed that an electron wave which has a wavelength of λ and is accelerated at a voltage of E is 1, and an image is formed by a transmission wave ψ(r) which has been transmitted through a sample having a potential of φ(r) which is weak in scattering intensity. Then, the formed image as described above is discussed. The transmission wave ψ(r) can be expressed as follows.ψ(r)=exp(−iσφ)=cos σφ−i sin σφ (1)where σ=π/λE and φ=φ(r)·ΔZ. Here, if σφ is sufficiently smaller than π/2, the following approximation is possible.ψ(r)=1−iσφ (2) The electron microscope image is observed as the intensity of a wave function obtained by further subjecting an electron beam diffraction wave which is a Fourier transform of the above-mentioned transmission wave, to the Fourier transform by means of a lens action. The wave function of the electron beam diffraction image is a Fourier transform of Expression (2), and thus is expressed as follows.Q(g)=δ−iσΦ(g) (3)where δ is a Dirac δ function and represents a transmitted non-scattering wave, Φ(g) is a Fourier transform of φ and represents a scattering wave on a diffraction image plane, and g corresponds to 1/r. A phase difference of γ(g) is generated in the scattering wave due to influences of the spherical aberration of a lens or focus. When this phase difference is taken into consideration, exp−iγ(g) is applied to Expression (3), so that the following expression is obtained.Q(g)=δ−σΦ(g)sin γ(g)−iσΦ(g)cos γ(g) (4)A wave function on the image plane is a Fourier transform image of Expression (4), and when F is assumed as a sign representing the Fourier transform, the following expression is obtained.ψ(r)=1−σF{Φ(g)sin γ(g)}−iσF{Φ(g)cos γ(g)} (5) An observed intensity I(r) is ψ(r) ψ(r)*, and hence when the second-order term of σφ is omitted, the following expression is obtained. I ( r ) ≅ 1 - 2 σ F { Φ ( g ) sin γ ( g ) } = 1 - 2 σ ∫ Φ ( g ) sin γ ( g ) exp ( - i g · r ) · ⅆ g ( 6 ) Here, ∫Φ(g) exp(−ig·r)·dg is a Fourier transform of the diffraction image, and is ψ(−r) on the lower surface of the sample. Accordingly, the following expression is obtained.I(r)=1−2σψ(−r)*F sin γ(g) (7)where * represents a convolution operation defined by f(x)*h(x)=∫f(x)h(x−X)dX. In order to maximize the observed intensity, it is necessary to change γ(g) by a given measure to make sin γ(g)−1 or +1. At this time, the following expression is obtained.I(r)=1±2σψ(−r) (8) An amount of change in the intensity of the observed image is proportional to an electrostatic potential of an object projected in an entering electron beam direction. A function sin γ(g) which transmits phase information which contributes to the contrast to the image is referred to as a phase contrast transmitting function (phase CTF). However, in actuality, it is difficult to manufacture a transmission electron microscope in which sin γ(g) is constantly kept −1 or +1. In a conventional transmission electron microscope (CTEM), it was merely possible to make sin γ(g) −1 or +1 only for part of g. This is because focus, the spherical aberration of a lens, a beam divergence, and the deviation from an in-focus position due to a chromatic aberration affect the CTF. For example, in an electron microscope with an accelerating voltage of 300 kV, when the defocus is 48 nm, the spherical aberration is 0.9 mm, the deviation from the in-focus position due to the chromatic aberration is 5 nm, and the beam divergence is 0.3 mrad, the CTF is as shown in FIG. 1. The horizontal axis thereof is g in units of 1/nm. In a region surrounded by a dotted line in FIG. 1, sin γ(g) exhibits a value close to −1, and hence diffraction information (Fourier transform components) contained in this region contributes to an image formed by the transmission electron microscope, at a relatively high intensity. As this region is broader, the formed image shows information which is more faithful to the original information of a sample. Therefore, the design of the electron microscope and focusing at the time of photographing are performed so that this region becomes broader. The focus which allows as much diffraction information as possible to contribute to the image formation is referred to as Sherzer focus, which is named after the name of the proposer thereof. In the case where photographing is performed under the above-mentioned conditions by using a normal transmission electron microscope, almost no diffraction information outside of the region indicated by the dotted line in FIG. 1 can be reflected to the electron microscope image. In order to form an image of the diffraction information outside of this region, it is necessary to change the focus and change the shape of the CTF, to thereby cause sin γ(g) to exhibit a value close to −1 or +1 at g at which the necessary diffraction information exists. However, even in that case, there are some pieces of diffraction information which do not contribute to the image formation. An influence of this loss of the diffraction information on the formed electron microscope image is described by using: Fourier transform images which are simple pictures; and images which are reproduced by applying modulation to the Fourier transform image, removing part of the diffraction information therefrom, and then subjecting the image to the inverse Fourier transform. The first Fourier transform corresponds to the electron beam diffraction image in the transmission electron microscope, the application of modulation corresponds to the addition of the CTF inherent to the electron microscope, and the calculation of the inverse Fourier transform image thereof corresponds to the image formation in the transmission electron microscope. First, the original space information is illustrated in FIG. 2(a). This is a picture which is obtained by superimposing an image having a regular structure similar to a crystal structure onto a picture of a waterfall at the upper left part of the figure. The following description is given on the assumption that a portion indicated by a dark contrast in the picture corresponds to a portion having a higher potential within the sample observed by the transmission electron microscope. The Fourier transform image of FIG. 2(a) is illustrated in FIG. 2(b). The image has an appearance totally different from its original image. This Fourier transform image corresponds to an electron beam diffraction image in the case of the transmission electron microscope. Spots which indicate the Fourier transform of the regular structure superimposed onto the image are observed in FIG. 2(b). In addition, a point at the center thereof corresponds to a transmission wave in the transmission electron microscope, and the Fourier transform image of the waterfall appearing in the picture is observed in the vicinity thereof, though at a low intensity. Here, the case where components outside of FIG. 2(b) do not contribute to the image formation by CTF modulation of the transmission electron microscope is discussed. The Fourier transform image after the CTF modulation which is assumed in this case is illustrated in FIG. 2(c). To simplify phenomenon, it is assumed that the CTF exhibits 1 when g is from 0 to gC and exhibits 0 when g is equal to or larger than gC. The assumed CTF is illustrated in FIG. 2(b). When the CTF modulation is applied to the Fourier transform image, it was assumed that all pieces of information located at the same radius g with respect to the center of the Fourier transform image are subjected to the modulation of CTF (g). In the case of the transmission electron microscope, this assumption corresponds to the state where there is not any astigmatism. FIG. 2(c) is the same as FIG. 2(b) near the center, whereas, in FIG. 2(c), the CTF exhibits 0 in the region having a radius equal to or larger than gC. The Fourier transform image of FIG. 2(c) is illustrated in FIG. 2(d). This operation is equivalent to the image formation in the transmission electron microscope. In FIG. 2(d), although the original picture is roughly reflected, detailed information on splashes of the waterfall and the like has been lost. Such lost space information d is space information smaller than 1/gC which is an inverse of gC which is given when the modulation is applied to the Fourier transform. For example, some diffraction waves gcrystal which are obtained by the Fourier transform of the regular structure at the upper left part of FIG. 2(a) appear in regions surrounded by a circle in FIG. 2(b). The diffraction waves gcrystal which appear in FIG. 2(b) are cut by performing the CTF modulation, with the result that information on the diffraction waves is lost in FIG. 2(c). As a result of subjecting FIG. 2(c) to the Fourier transform to form an image, the regular (crystal) structure which originally exists at the upper left part of FIG. 2(a) is lost in the formed image of FIG. 2(d). On the other hand, it is assumed that CTF modulation is applied to FIG. 2(b), to thereby form an image of diffraction information as illustrated in FIG. 2(e). In this CTF modulation, the CTF exhibits 0 in a region having a radius equal to or smaller than gC1 near the center and a region having a radius equal to or larger than gC2. The Fourier transform image of FIG. 2(e) is illustrated in FIG. 2(f). The information on the diffraction waves gcrystal is left in FIG. 2(e), and hence the regular (crystal) structure which originally exists at the upper left part of FIG. 2(a) is reproduced. However, it can be understood that the contrasts of the waterfall and a shore are remarkably reduced. This lost information is a structure which is larger than dC1=1/gC1. In this way, as a result of applying the CTF modulation to the Fourier transform, part of the diffraction information does not contribute to the image formation, which leads to a problem that the original structure of the sample is not reflected in the image formed by this Fourier transform. Accordingly, ideally, the CTF required for the transmission electron microscope always exhibits −1 or +1. However, in actuality, as described above, it is difficult to design the transmission electron microscope so that the CTF always exhibits −1 or +1. In the transmission electron microscope, as described above, the CTF has an undulate form as shown in FIG. 1 which is decided by the spherical aberration of the objective lens, the focus at the time of photographing, the beam divergence, and the chromatic aberration. Because the required space information r is different depending on a structure to be observed, the focus and the spherical aberration need to be changed. On this occasion, the spherical aberration of the objective lens is an inherent value affected by a gap of the designed objective lens, and hence fine adjustment is performed by the focus. In addition, the transmission electron microscope has a mechanism in which a sample is inserted into the gap of the objective lens. Therefore, there is a physical limit to the reduction in the gap thereof, and there is a limit to the design of the objective lens. Therefore, the CTF in the transmission electron microscope is subjected to various restrictions, and thus can exhibit a value close to −1 or +1 only within a limited range, with the result that the resolution is restricted. In recent years, it has been required to perform photographing while variously changing elements which affect the CTF, and a spherical aberration correcting apparatus capable of changing the spherical aberration, which was a value inherent to an objective lens conventionally, has been developed. The CTF under the following conditions is as shown in FIG. 3. That is, the spherical aberration is corrected to 0.005 mm by using this spherical aberration correcting apparatus, the accelerating voltage is 300 kV, the defocus is 4.5 nm, the deviation from the in-focus position due to the chromatic aberration is 3 nm, and the beam divergence is 0.3 mrad. In the CTF shown in FIG. 3, an S region in which sin(γ) exhibits −1 is broader than that in the CTF shown in FIG. 1, and sin(γ) exhibits a value up to a portion in which g is approximately 10. From this fact, it is understood that a resolution equal to or smaller than 0.1 nm can be achieved theoretically by using this spherical aberration correcting apparatus. With regard to the case where a normal crystal structure is observed, it can be said that the resolution of the electron microscope has reached a sufficient level, partly because of the development of the spherical aberration correcting apparatus. However, on the other hand, information on an L region in FIG. 3 has been lost. Hereinafter, this problem is described. In consideration of the relation between the CTF and the TEM image which is described with reference to FIG. 2, the loss of the L region in the CTF in FIG. 3 corresponds to the loss of information on a large structure. In an actual TEM sample, this large information is, for example, information in which the contrast of a cell organelle in an embedding resin and the like are contained in this region. In the observation using a conventional biological TEM, a sample is stained, and a small objective diaphragm is used, to thereby obtain the contrast of the cell organelle. However, when the objective diaphragm is made smaller, there arises a side effect that the resolution of a TEM image becomes lower. Therefore, it has been necessary to gropingly find out conditions for the best observation, in view of the relation between the contrast and the size of a structure to be observed. A method which has attracted attention in recent years as a solution to this problem is a phase difference transmission electron microscope method. This method is a method of using a thin film with a small hole as an objective diaphragm, and has a feature that a diffraction wave other than a transmission wave is transmitted through the thin film part and a phase difference of π/2 is given to the diffraction wave at this time. For example, in the case where an objective diaphragm which gives a phase difference of π/2 to a diffraction wave having g=0.5 or larger is used in a TEM, the CTF is as shown in FIG. 4. In this TEM, the spherical aberration is corrected to 0.005 mm by using the spherical aberration correcting apparatus, the accelerating voltage is 300 kV, the defocus is 4.5 nm, the deviation from the in-focus position due to the chromatic aberration is 3 nm, and the beam divergence is 0.3 mrad. From the CTF shown in FIG. 4, it is understood that a value of sin(γ) exhibits −1 from the beginning by using a phase plate. This is the very effect which is obtained by using the phase plate to thereby shift the phase of the diffraction wave by π/2 in a region having g=0.5 or larger, and a previous CTEM does not have such a feature. There has been known that this effect enables observation even when the structure of a cell organelle is not stained, in a phase TEM (hereinafter, abbreviated to PTEM) using a phase plate with a further smaller hole. (R. Danev and K. Nagayama, Ultramicroscopy, 88 (2001) 243. It is understood that, according to the above-mentioned method, sin(γ) exhibits 0 near g=7.8 at the time of the observation using the PTEM in which a phase plate is used in a spherical aberration correcting apparatus capable of obtaining information of 0.1 nm. In this condition, part of information is lost, and hence it is not possible to obtain all information that the sample originally has. An object of the present invention relates to providing a CTF in which |sin(γ)| is constantly kept +1 for all values of g. In addition, an object of the present invention relates to adjusting a phase difference in an apparatus using an electron beam and thus improving the coherence thereof. This is because, when an electron beam is to be converged by a lens or an image of an electron microscope using the lens is to be formed, an influence of a spherical aberration causes a phase difference of the electron beam and thus prevents an interference effect from being sufficiently obtained. The present invention relates to adjusting a phase difference due to a difference in electron beam path which is caused when the electron beam is converged by a lens or an image of the electron beam is formed, and eliminating the difference. Specifically, for example, a phase plate having a thickness which changes from its center in the radial direction is used, and a thickness effect, a potential effect, or these two effects are used to thereby adjust a phase of the electron beam. In addition, for example, the present invention is realized by a potential adjusting function, a temperature adjusting function, a phase plate atmosphere gas pressure adjusting mechanism, a phase plate astigmatism correcting mechanism, a phase plate tilt position height adjusting mechanism, and the like. According to the present invention, it is possible to make higher the resolution of a PTEM image, to thereby realize a versatile use thereof. In the present embodiment, as illustrated in FIG. 5(a), a phase plate 510 is disposed at a back focal plane of an objective lens 502, and a phase plate holder 504 including a mechanism which heats, tilts, and displaces the phase plate 510 and applies a voltage to the phase plate 510 is provided. The phase plate 510 has a shape as illustrated in FIG. 5(b), and is a circular plate having a small hole. A cross sectional shape thereof has a thickness which changes in the radial direction as needed. In actuality, it is desirable to dispose the phase plates 510 having several shapes, and select the phase plate 510 to be used in accordance with a structure, characteristics, or an observation purpose of an observed sample. It is desirable to select an appropriate value for the voltage to be applied to the phase plate 510 in accordance with the structure, the characteristics, and the observation purpose of the observed sample. Similarly to the CTEM, an electron microscope including the phase plate 510 is provided with an objective stigma for performing astigmatism correction of the objective lens 502, and is also provided with a phase plate stigma 506 for performing astigmatism correction of the phase plate 510 which functions as a lens. In addition, a phase plate chamber 505 is provided for a reduction in charge up due to electron beam irradiation of the phase plate 510, and a mechanism which enables gas introduction is provided therein. The phase plate chamber 505 has a hole having a diameter which is large enough to allow the electron beam to pass therethrough. The degree of vacuum in the phase plate chamber 505 is adjusted in accordance with the balance between an amount of introduced gas and an exhaust velocity. In addition, potential distribution around the phase plate 510 is changed by gas introduction, and hence sufficient adjustment for use is required, so that a phase plate chamber degree-of-vacuum adjusting function using a PC may be provided. FIG. 6 is a schematic view illustrating an optical system in which a spherical aberration correction lens is disposed between the phase plate chamber and the objective lens. This configuration makes it possible to incorporate, as an electron microscope function, the combination of a spherical aberration correcting function and a phase difference adjusting function. The position adjustment of the phase plate with respect to the electron beam is difficult for a normal operator, and hence it is effective to provide an automatic position adjusting function, for the purpose of facilitating the operation. According to the present embodiment, it is possible to correct a spherical aberration of an imaging system of the transmission electron microscope. There is an effect of improving the coherence at the time of use for the irradiation system of the scanning electron microscope, to thereby improve the brightness of an electron beam probe. The use for the irradiation system of the transmission electron microscope makes it possible to irradiate a sample with an electron beam having high coherence. Further, in comparison with a spherical aberration corrector which uses a large number of electron lenses, it is possible to provide a similar effect at relatively lower costs. This effect can be used for the imaging system including the objective lens in the transmission electron microscope. It should be noted that, in the present embodiment, there is disclosed an electron microscope including: means for adjusting a phase difference between a portion on an optical axis and a portion passing outside of the optical axis, of an electron beam passing through the electron microscope; and a phase plate having a thickness which changes in a radial direction. In addition, in the present embodiment, there is disclosed an electron microscope including: means for adjusting a phase difference between a portion on an optical axis and a portion passing outside of the optical axis, of an electron beam passing through the electron microscope; and a phase plate having a potential which changes in a radial direction. In addition, in the present embodiment, there is disclosed an electron microscope including: means for adjusting a phase difference between a portion on an optical axis and a portion passing outside of the optical axis, of an electron beam passing through the electron microscope; and a phase plate supporting mechanism having a function of adjusting a potential. In addition, in the present embodiment, there is disclosed an electron microscope including: means for adjusting a phase difference between a portion on an optical axis and a portion passing outside of the optical axis, of an electron beam passing through the electron microscope; and a mechanism for performing, if a change in phase does not uniformly occur on the same concentric circle, correction of the change in phase. In addition, in the present embodiment, there is disclosed the electron microscope, in which the phase plate is a conductive crystalline phase plate. In addition, in the present embodiment, there is disclosed the electron microscope, in which the phase plate is a conductive amorphous phase plate. In addition, in the present embodiment, there is disclosed the electron microscope further including a phase plate supporting mechanism including: a mechanism for adjusting a tilt, a position, and/or a height of the phase plate; and a mechanism for adjusting temperature. In addition, in the present embodiment, there is disclosed the electron microscope further including a phase plate chamber, an electron beam passage port, a gas introduction pipe, a gas flow adjustment valve, and an exhaust apparatus, for adjusting a gas pressure in the vicinity of the phase plate. In addition, in the present embodiment, there is disclosed an electron beam phase adjuster, which is used for the electron microscope. In addition, in the present embodiment, there is disclosed: a phase difference electron microscope; a transmission electron microscope which is configured by combining the phase difference electron microscope and a spherical aberration corrector; a scanning electron microscope; a scanning transmission electron microscope; or a transmission electron microscope. In addition, there is disclosed the electron microscope further including a mechanism which is capable of automatically performing axis adjustment of a phase adjusting mechanism. Hereinafter, the above-mentioned and other novel features and effects of the present invention are described with reference to the drawings. It should be noted that the drawings are employed for the understanding of the invention, and do not restrict the scope of the claims. FIG. 5(a) illustrates a schematic mechanism of the present embodiment. In the present embodiment, description is given of an electron microscope including a phase plate in the vicinity of a diffraction plane of an electron beam. There is provided a function of causing the phase plate holder 504 to heat, tilt, and displace the phase plate 510 and to apply a voltage to the phase plate 510. The phase plate 510 has a mechanism which is inserted from the outside into the phase plate chamber 505 by using the phase plate holder 504. The phase plate chamber 505 has a hole having a diameter which is large enough to allow the electron beam to pass therethrough. In addition, the phase plate chamber 505 includes: a gas introducing mechanism including a gas introduction valve adjusting function 509 and a gas introduction pipe 516; and an exhausting mechanism including an exhaust pipe 512 and an exhaust apparatus 514. The phase plate 510 has a shape as illustrated in FIG. 5(b), and is a circular plate having a small hole. A cross sectional shape of the phase plate has a thickness which changes in the radial direction as needed. Hereinafter, description is given of an example of an effect obtained by changing the thickness in the radial direction. FIG. 7 shows a cross sectional shape of only one side of the phase plate having a thickness which does not change in the radial direction, from the center toward the outer side. A hole is opened at the center, and the thickness thereof is 0. An outer portion from a radius R1 has a uniform thickness of t. In addition, it is assumed that the thickness of t is a thickness which changes a phase of the electron beam by exactly π/2 by using the phase plate. t is decided by a material used for the phase plate and the accelerating voltage of the electron beam. In the case where this phase plate is used in a TEM in which the accelerating voltage is 300 kV, the defocus is 4.5 nm, the spherical aberration is 0.005 mm, the deviation from the in-focus position due to the chromatic aberration is 3 nm, and the beam divergence is 0.3 mrad, the CTF is as shown in FIG. 7(b). From this figure, it is understood that a nano-sized or larger structure can be observed with an excellent contrast, but sin(γ) exhibits 0 near g=7.8. In this condition, part of information is lost, and hence it is not possible to obtain all information that the sample originally has. In the TEM in which the accelerating voltage is 300 kV, the defocus is 4.5 nm, the spherical aberration is 0.005 mm, the deviation from the in-focus position due to the chromatic aberration is 3 nm, and the beam divergence is 0.3 mrad, characteristics of proper change in phase using a phase plate for forming an image of the largest amount of information are shown in FIG. 8(a). The horizontal axis thereof is g which is a value obtained by dividing a radius r of the phase plate by a camera length L. The vertical axis thereof shows a proper amount by which the phase of the electron beam should be changed by the phase plate at the position of each radius. The amount of change in phase is set to 2π-π/2 near the center, and the reason for this will be described later. Assuming that the camera length is L (nm·mm), the radius r on the phase plate is associated with a reciprocal lattice vector g as shown below in Expression (9).g=r/L (9) Assuming that the amount of change in phase of the TEM when the TEM does not use the phase plate is γ0(g), the proper amount of change in phase referred to here can be expressed as follows.Proper amount of change in phase Ps=2πn±π/2−γ0(g) (10)where n is an arbitrary integer. As a result of this phase correction, sin(γ) constantly exhibits −1 or 1, and description thereof is given below. In the calculation of the CTF, in actuality, π/2 which is a change in phase of electrons scattered by the sample is taken into consideration, and cos(λ/2−γ0(g)) is calculated, with the result that sin(γ) is derived. When the effect Ps of the phase plate is additionally applied, the following expression is obtained.cos(−Ps+π/2−γ0(g)) or sin(Ps+γ0(g)) (11) As a result, the following expression is obtained.cos(−2πn±π/2+γ0(g)+π/2−γ0(g))=cos(−2πn+π/2±π/2)=±1 Const. (12a)orsin(2πn±π/2−γ0(g)+γ0(g))=sin(2πn±π/2)=±1 Const. (12b) Here, γ0(g) is shown below in Expression (13).γ0(g)=πCsλ3g4/2−πλΔfg2 (13)where Cs is the spherical aberration, λ is the wavelength of the electron beam, and Δf is the defocus. The usage conditions of the electron microscope are given to Expression (13), whereby the proper amount of change in phase is decided. FIG. 8(b) shows an ideal CTF with the phase being properly corrected. In this state, all images of from a large structure to a small structure can be formed. It is one of means for bringing the CTF into an ideal state to change the thickness of the phase plate in the radial direction. γ0(g) variously changes depending on the usage state of the TEM, and hence an ideal shape of the phase plate is also varied. However, in a rough classification, there are four types: a type which becomes thicker gradually from the center toward the outer side; a type which once becomes thicker midway from the center toward the outer side and then becomes thinner; a type which once becomes thinner midway from the center toward the outer side and then becomes thicker; and a type which becomes thinner gradually from the center toward the outer side. An amount P(r) of change in phase of the electron beam by using the phase plate is shown below in Expression (14) by an inherent potential φ decided by the material of the phase plate, a thickness T(r) of the phase plate, and a potential V(r) of the phase plate.P(r)=[2πe(E0+E)/λE(2E0+E)]{φ+V(r)}T(r) (14)where E0 is rest energy of electrons and E is energy of entering electrons. When the thickness of the phase plate is changed in the radial direction, according to Expression (14), it is possible to change the amount of change in phase of the electron beam in the radial direction by using the phase plate. This effect is achieved by: an effect obtained by the change in thickness of the phase plate itself; and an effect obtained by the change in charging characteristics of the phase plate due to the change in thickness in the radial direction. Because the thickness of the phase plate cannot be made zero, in order to obtain ideal distribution of the change in phase, it is effective to perform such adjustment that a phase difference of (2n±½)π is given in the vicinity of the transmission wave. However, if n is set to a large value, the transmittance of the electron beam itself becomes lower to reduce the contrast of an image, and hence n cannot be set to an excessively large value. From that point of view, the proper amount of change in phase shown in FIG. 8 is set to (2−½)π. In general, a thin film material is positively charged by electron beam irradiation, and a larger amount of irradiation with the electron beam leads to stronger charging. An electron beam diffraction image exhibits distribution of various electron beam intensities in the radial direction, and hence it is necessary to change the shape of the phase plate in accordance with the electron beam diffraction image of the observation sample. However, a pattern of the electron beam diffraction image is different depending on the sample, and is varied only by the change in observation field of view. Accordingly, the charging by the irradiation of the phase plate with the electron beam is the most significant factor which complicates the operability of the PTEM. In order to solve this problem, in the present embodiment, there is provided a mechanism capable of applying an arbitrary potential to the phase plate. The charging of the phase plate occurs to the highest degree on an edge of the small hole at the center of the phase plate, which is located in the vicinity of the transmission wave of the electron beam diffraction image. This is because a large background exists in the vicinity of the transmission wave of the electron beam diffraction image. Here, it is assumed that the central part of the phase plate is charged to 7 V by the electron beam irradiation. In that case, the entire phase plate is charged to 7 V or higher, whereby the charged potential becomes constant in the radial direction of the phase plate. In this state, it is possible to substantially control the amount of change in phase of the electron beam in the radial direction of the phase plate by means of the thickness of the phase plate. In addition, a potential applied to the phase plate is changed to the charged potential near the center of the phase plate, whereby the potential in the radial direction can be changed arbitrarily. This mechanism is advantageous when there is a slight difference between the shape of the phase plate in use and an ideal shape of the phase plate which is required by the conditions of the electron microscope currently used for the observation. Effects which act on the change in phase of the electron beam at this time are a thickness effect and a potential effect of the phase plate. Another measure for controlling the charging can be conceived. The above-mentioned method is a control method using the mechanism which holds a charged state, and alternatively, there is also a method of controlling the charging by using a gas species. For this purpose, in the present embodiment, a gas introduction port and an exhaust port are provided. In the case where charging occurs due to an influence of the electron beam, the charging is balanced by the exchange between a gas species and electrons. As a gas pressure is higher, an effect of suppressing the charging is higher. However, the gas pressure cannot be made worse than the degree of vacuum required by an electron gun of an electron beam microscope, and hence there is a restriction. The gas pressure is decided by the relation between the size of an electron beam introduction port, the flow rate of an introduced gas, and the exhaust velocity. It is possible to face a leading end of a gas pipe toward the vicinity of the center of the phase plate which is charged to the highest degree so that the introduced gas can effectively suppress the charging. An example thereof is illustrated in FIG. 5(b). The CTF of the PTEM is evidently decided by the phase difference between the transmission wave and the diffraction wave. A method of adjusting the phase of the diffraction wave to the best condition by means of the thickness or the potential of the phase plate is one of the points of the present embodiment. An ideal shape of the phase plate is changed by the accelerating voltage at the time of photographing by the electron microscope, the defocus, the spherical aberration, the deviation from the in-focus position due to the chromatic aberration, and the beam divergence. Therefore, it is desirable to provide a mechanism in which several phase plates corresponding to conditions which are more likely to be used for observation can be selected. For example, as illustrated in FIG. 11, a phase plate A 1102, a phase plate B 1103, a phase plate C 1104, and a phase plate D 1105 are provided in a thick phase plate supporting electrode 1101. When the phase plate is charged, the phase plate has a function as an electrostatic lens. It may be considered that there is not a large influence when the charged potential is still small, but in the case of using the phase plate whose hole at the center of the phase plate is small, the axis adjustment of the phase plate affects the image quality. For the axis displacement of the phase plate, there are x, y, and z as well as Tilt and Azim. A method of correcting a position and a tilt of the phase plate is described below. First, the axis adjustment and various types of astigmatism correction are performed on the electron microscope without the insertion of the phase plate. After the adjustment of the electron microscope has been finished, the electron beam diffraction image is checked, to thereby check at which part of a CCD camera the center of the diffraction image appears. In order to prevent the CCD camera from being broken by strong electron beam irradiation, a filter is used for preventing burnout. The phase plate is inserted, and the transmission wave of the electron beam diffraction image is caused to reach the phase plate. An imaging lens is adjusted, and the electron beam diffraction image of the phase plate, which is formed by the electrons radiated to the phase plate, is brought into an observable state. If the phase plate is made of a single-crystal material, the tilt of the phase plate with respect to the electron beam can be accurately determined by observing a diffraction pattern of the phase plate using the CCD camera. Both of Tilt and Azim are adjusted, and the tilt adjustment is continued with feedback until the designed tilt and the actual tilt of the phase plate coincide with each other. Next, x and y fine adjustments are moved so that the hole of the phase plate is positioned at the center of the electron beam diffraction image. The image formed by the PTEM is checked, and a z position of the phase plate is examined. Specifically, when an image is shown at low magnification, if the z position of the phase plate is largely different from the image plane of the electron beam diffraction image, a region in which a phase difference image appears becomes smaller. In relation to the positional relation between the height z of the phase plate and the image plane of the electron beam diffraction image, when the phase plate is moved farther from the image plane of the electron beam diffraction image, it is possible to give the contrast to a larger structure. However, the observation field of view becomes narrower, and blurring occurs on the periphery of the image. On the other hand, when the phase plate is positioned exactly at the image plane of the electron beam diffraction image, the observation field of view becomes largest, and blurring on the periphery can be reduced. However, the size of a structure to which the contrast can be given is a designed value of the phase plate. It is desirable to make selective use depending on the intended purpose. The position of the phase plate is correlated with the size of the phase difference image region observed by the PTEM, and hence the z position of the phase plate can be roughly adjusted by monitoring the size of the phase difference image region. At this time, because there may be a move in x or y, the x or y position adjustment is performed again. Lastly, the voltage center of the entire PTEM is checked, and if the voltage center is deviated more than an allowable value, the position adjustment of the phase plate from the tilt correction is performed. After the position adjustment of the phase plate has been finished, the adjustment of the phase plate stigma occurring in the phase plate is performed. The position and tilt adjustments of the phase plate require time and effort, and hence it is desirable to provide a mechanism capable of automatic processing therefor. In order to check whether or not the phase plate functions in an ideal state, an average amorphous sample is found in the vicinity of the observation sample, and an image obtained by photographing the found region by the CCD camera is subjected to the Fourier transform. In general, the Fourier transform image of the TEM image is used for examining characteristics of the CTF. It is equally effective to attach a sample for PTEM adjustment in advance in the vicinity of the observation sample. If the phase plate does not function properly, it is necessary to take a measure thereagainst. For example, the used phase plate is changed, or the applied voltage is changed. In the case where the phase plate is used together with the spherical aberration correcting apparatus, it is equally effective to change the spherical aberration. As a matter of course, changing the focus is one of the measures which can be conceived naturally. It is checked whether or not the contrast can be obtained at a magnification to be set for observation, whereby a precious sample can be observed with little damage within a short time. If the irradiation of the phase plate with the electron beam causes contamination on the phase plate, the thickness of the phase plate is partially changed, so that the function which is originally designed as the phase plate is lost. In order to reduce such contamination, the observation is performed while heating the phase plate, and the serviceable time of the phase plate can be further extended by providing a cold trap in the phase plate chamber. Metal having good conductive properties is the most suitable for a material of the phase plate. In addition, because the phase plate is irradiated with the strong electron beam while being heated, a heat-resistant material is preferable. It is desirable that a crystalline structure of the phase plate be uniform, and it is desirable that the crystalline structure thereof be single-crystal or amorphous. In the case of an amorphous material, the scattering wave is generated in the vicinity of the electron beam which has been transmitted through the phase plate, and hence a certain amount of noise of the electron beam scattered by the phase plate mixes into the field of view of the phase difference image. As a result, a random pattern peculiar to the amorphous material is superimposed on the phase difference image. However, the amorphous phase plate is easily manufactured, and thus is effective for a sample having a large structure. In the present embodiment, the used phase plate is made of a single-crystal material and is designed so as to make higher-order diffraction of the electron beam. In the case of the single-crystal phase plate, noise in the vicinity of the transmission wave is reduced. Accordingly, noise components of the phase difference image can be reduced. In addition, in the case of the single-crystal phase plate, noise appears in a regular stripe pattern deriving from a lattice image, and hence it is possible to easily remove the noise by the IFFT (inverse Fourier transform). For reference, a scattering pattern of the amorphous phase plate and a scattering pattern of a single-crystal higher excitation phase plate are illustrated in FIGS. 10(a) and 10(b), respectively. When the position and tilt adjustments of the phase plate and the adjustment of the phase plate stigma are completed and it can be confirmed that the phase plate normally functions, the adjustment of the PTEM comes to an end. It is possible to search the observation field of view and acquire the data similarly to the TEM. Embodiment 2 is illustrated in FIG. 12. In the present embodiment, there is disclosed a scanning electron microscope which converges an electron beam on a sample surface for observation, the scanning electron microscope including a phase adjusting apparatus which adjusts a phase difference on the sample surface between electrons having different irradiation angles, which is caused by a spherical aberration of a lens provided between a sample and an electron source. According to the present embodiment, it is possible to improve the coherence when a large diaphragm is used and the irradiation angle is made larger, so that the brightness of an electron probe is improved. As a result, high-sensitivity analysis and photographing of an image with a high S/N ratio are possible. The use as a scanning transmission electron microscope, which is configured by providing the above-mentioned scanning electron microscope with a transmitted electron detector and a scattered electron detector, is also possible. In the case of the use as the scanning electron microscope or the scanning transmission electron microscope, the proper amount of change in phase is different from that of Embodiment 1. In the case of the use as the scanning microscope, a phase difference γ(α) of an electron beam reaching the sample for each irradiation angle α is shown below in Expression (15).γ(α)=πCsα4/2λ−πΔfα2/λ (15) At this time, it is not necessary to consider the change in phase π/2 due to sample scattering in the phase modulation of the irradiation system, and hence the proper amount of change in phase is shown below in Expression (16).Proper amount of change in phase=2πn−γ(α) (16)where n is an integer. For example, in the electron microscope with the accelerating voltage of 200 kV, when the defocus is 10 nm and the spherical aberration is 0.5 mm, the proper amount of change in phase is as shown in FIG. 13(b). In FIG. 13(b), the horizontal axis thereof is α, and a distance R in the radial direction of the phase plate and α are associated with each other as follows, on the basis of the positional relation between a virtual light source, the phase plate, the objective lens, and the sample.R=tan(α)(fb/fa)Pz (17)The above expression is established on the assumption of the simplest irradiation system. In actuality, there is an electron microscope in which several converging lenses are used, and hence the association between R and a cannot be shown as simple as Expression (17), but is an extension of Expression (17) basically. In any system, the distance R in the radial direction of the phase plate and the irradiation angle α can be associated with each other. In the case of applying the present embodiment to the irradiation system, a phase adjusting mechanism may be disposed at any position between the electron beam source and the sample. However, in the scanning microscope, the optical axis of the electron beam is displaced at the time of scanning with the electron beam, and hence it is desirable that the phase adjusting mechanism be disposed on the electron beam source side with respect to a scanning coil. In a normal STEM, it is sufficient if the coherence can be secured within a range of approximately 10 mrad, and it is found out that, according to the present embodiment, the coherence can be secured satisfactorily up to approximately 20 mrad. Because the thickness of the phase plate cannot be made zero, there is a limit to an application range. In the present embodiment, the phase plate having a thickness which is constant at 20 mrad or larger is adopted. FIGS. 14(a) and 14(b) show the coherences before and after the phase adjustment by means of cos(−γ), respectively. A hole is not opened at the center of the phase plate, and this is a feature of Embodiment 2. The four patterns can be conceived as the patterns of the shape as described in Embodiment 1. As illustrated in FIG. 15, in the scanning transmission electron microscope, the transmitted electron detector is replaced with an imaging lens 1508, and an image photographing apparatus is combined, whereby the transmission electron microscope including the phase adjusting mechanism can be configured. It becomes possible to uniformly adjust, on the sample surface, a phase shift of irradiation electrons which occurs in the irradiation system. For example, in the case, such as in electron beam holography, where information on a change in phase is recorded and evaluated, an electron beam with a uniform phase is required in a wide range, and hence the present invention is particularly effective. In recent years, a technology of observing an organic material such as a cell organelle, protein, and a high molecule without staining the material by using a TEM has attracted attention. At present, although only limited researchers have started pioneering studies on the PTEM, if the PTEM is widely used in the world as a general-purpose apparatus to be utilized by various research institutes, the progress of research results in the cell science and the medical science can be expected almost as a matter of course. When the present invention is applied to the irradiation system of the scanning electron microscope or the scanning transmission electron microscope, it is possible to form an electron beam probe having high coherence, which enables high-sensitivity analysis and high-resolution observation. When the present invention is applied to the irradiation system of the transmission electron microscope, it is possible to irradiate a sample with an electron beam having high coherence, and this is effective in the case, such as in holography, where analysis is performed using the interference between electron beams. 501, 601 object surface 502, 602, 1205, 1303, 1506 objective lens 503, 603 diffraction plane 504 phase plate holder 505 phase plate chamber 506, 612 phase plate stigma 507 imaging lens 508 image plane 509 gas introduction valve adjusting function 510 phase plate 511 heater 512 exhaust pipe 513 voltage applying means 514 exhaust apparatus 515 optical axis 516 gas introduction pipe 517 electrode for voltage application 518 cross section of phase plate 604 transfer dublet 1 605 hexapole 1 606 transfer dublet 2 607 hexapole 2 608 ADL 609 image plane 610 intermediate lens 611 diffraction plane 2 613 imaging lens 614 image plane 615 spherical aberration correction lens 616 phase plate 617 heater 618 voltage applying means 1101 phase plate supporting electrode 1102 phase plate A 1103 phase plate B 1104 phase plate C 1105 phase plate D 1201, 1501 electron beam source 1202, 1502 converging lens 1 1203, 1504 phase difference adjuster 1204, 1503 converging lens 2 1206, 1505 secondary electron detector 1207, 1304, 1507 object surface (sample) 1208 scattered electron detector 1209 transmitted electron detector 1301 virtual light source 1302 phase plate 1508 imaging lens 1509 phase change analyzing apparatus 1510 image storing mechanism 1511 electron energy loss analyzing apparatus |
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claims | 1. A method for maintaining liquid lithium on a surface area of internal walls of a reactor chamber, the method comprising:installing at least one tile on the surface area of the internal walls of the reactor chamber, wherein the at least one tile is manufactured from a high-temperature resistant, porous open-cell material comprising an internal network;pumping the liquid lithium through the interior network of the at least one tile;circulating the liquid lithium throughout the interior network of the at least one tile via at least one open cell to allow for the liquid lithium to seep from the interior network through the porous open-cell material to reach an external surface of the at least one tile that faces the interior of the reactor chamber, wherein the porous open-cell material retains the liquid lithium in place on the internal walls of the reactor chamber against gravity and electromagnetic forces; andoutputting the circulated liquid lithium from the at least one tile. 2. The method of claim 1, wherein the reactor chamber is employed in a fusion reactor. 3. The method of claim 1, wherein the at least one tile has an irregular shape. 4. The method of claim 1, wherein the at least one tile has a regular shape. 5. The method of claim 1, wherein the high-temperature resistant, porous material is a ceramic material. 6. The method of claim 1, wherein the high-temperature resistant, porous material is a metallic foam. 7. The method of claim 1, wherein the at least one tile has a constant porosity. 8. The method of claim 1, wherein the at least one tile has a varied porosity. 9. The method of claim 1, wherein the at least one tile includes an input plenum,wherein the liquid lithium is inputted into the at least one tile via the input plenum. 10. The method of claim 9, wherein the input plenum is a hollow piece of metal. 11. The method of claim 1, wherein the at least one tile includes an output plenum,wherein the liquid lithium is outputted from the at least one tile via the output plenum. 12. The method of claim 11, wherein the output plenum is a hollow piece of metal. 13. The method of claim 1, wherein a flow rate of the circulation of the liquid lithium within the interior network of the at least one tile is varied over time. |
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claims | 1. An x-ray computed tomography system that generates an x-ray beam with an x-ray generator and detects with an x-ray detector at least one characteristic of the x-ray beam generated by the x-ray generator, after the x-ray beam has passed through an object, the system comprising:a converting unit configured to obtain analog projection data outputted by the x-ray detector and to convert the analog projection data to digital projection data; anda processing unit configured to obtain the digital projection data from the converting unit, to detect overflow digital projection data that overflows a measuring range of the computed tomography system, and to correct the overflow digital projection data of the digital projection data by using a curve fitting function. 2. The x-ray computed tomography system of claim 1, wherein the processing unit comprises:an overflow unit configured to detect the overflow digital projection data; anda correction unit configured to correct the overflow digital projection data based on the overflow digital projection data obtained from the overflow unit, non-overflow digital projection data of the digital projection data obtained from the converting unit, and the curve fitting function of the processing unit. 3. The x-ray computed tomography system of claim 2, wherein the correction unit comprises:a first fitting unit configured to perform a first curve fitting function on the non-overflow digital projection data obtained from the converting unit;a second fitting unit configured to perform a second function fitting on a combination of the non-overflow digital projection data and the overflow digital projection data obtained from the converting unit and the overflow unit, respectively; anda weighting unit configured to weight and combine an output obtained from the first fitting unit and an output obtained from the second fitting unit to output a correction of the digital projection data,wherein a weight is adaptatively calculated by simulation by the weighting unit based on prior known digital projection data of the x-ray computed tomography system or the weight is obtained from a known lookup table. 4. The x-ray computed tomography system of claim 1, further comprising:a reconstruction unit configured to reconstruct an image of the object based on the corrected digital projection data obtained from the correction unit and the non-overflow digital projection data. 5. The x-ray computed tomography system of claim 4, further comprising:a display unit configured to display the image of the object reconstructed by the reconstruction unit. 6. The x-ray computed tomography system of claim 3, wherein the correction unit further comprises:an interpolation unit configured to identify overflow points in the digital projection data obtained from the converting unit and to linearly interpolate a group of overflow points if the group has a number of overflow points smaller than a predetermined number. 7. The x-ray computed tomography system of claim 6, wherein the first and second fitting units correct only groups of overflow points that have a number of overflow points bigger than the predetermined number. 8. The x-ray computed tomography system of claim 7, wherein the predetermined number is one. 9. The x-ray computed tomography system of claim 1, wherein the x-ray detector is an array detector having a plurality of detector elements. 10. The x-ray computed tomography system of claim 6, wherein the overflow unit comprises:a mapping unit configured to create an overflow map that identifies overflow points in the digital projection data obtained from the converting unit and to provide the overflow map to the correction unit. 11. The x-ray computed tomography system of claim 10, further comprising:a prior knowledge input unit configured to input the prior known digital projection data of the x-ray computed tomography system to the weighting unit. 12. The x-ray computed tomography system of claim 11, wherein the prior known digital projection data is water calibration data obtained by irradiating water with the x-ray beam in the computed tomography system and measuring with the x-ray detector the at least one characteristic of the x-ray beam after the x-ray beam has passed through the water. 13. The x-ray computed tomography system of claim 12, further comprising:a prior knowledge correction unit configured to calculate a correction of the overflow digital projection data based on an input obtained from the prior knowledge input data unit and an input obtained from the weighting unit; anda selection unit configured to select a best correction to be applied to the digital projection data based on an output obtained from the prior knowledge correction unit and an output obtained from the weighting unit. 14. The x-ray computed tomography system of claim 13, whereinthe first curve fitting function is a spline function,the second curve fitting function is a polynomial function, andthe selection unit selects the smallest correction from the correction of weighting unit, a correction of the second fitting unit, and the correction of the prior knowledge correction unit as the best selection. 15. The x-ray computed tomography system of claim 1, wherein the processing unit comprises a selection unit configured to select a correction algorithm based on characteristics of the overflow. 16. The x-ray computed tomography system of claim 1, wherein the processing unit is configured to correct the digital projection data along a channel direction of the x-ray detector. 17. A method for correcting an image of an object placed in an x-ray computed tomography system that generates an x-ray beam with an x-ray generator and detects with an x-ray detector at least one characteristic of the x-ray beam generated by the x-ray generator, after the x-ray beam has passed through the object, the method comprising:converting analog projection data outputted by the x-ray detector to digital projection data with a converting unit connected to the x-ray detector;detecting overflow digital projection data that overflows a measuring range of the computed tomography system with an overflow detecting unit connected to the converting unit; andcorrecting the overflow digital projection data with a correction unit connected to the overflow detecting unit by using a curve fitting function to produce a corrected image. 18. The method of claim 17, wherein the correcting comprises:correcting the overflow digital projection data with the correction unit based on the overflow digital projection data obtained from the overflow detecting unit, non-overflow digital projection data of the digital projection data obtained from the converting unit, and the curve fitting function. 19. The method of claim 18, wherein the correcting further comprises:performing a first curve fitting function with a first fitting unit on the non-overflow digital projection data obtained from the converting unit;performing a second curve fitting function with a second fitting unit on a combination of the non-overflow digital projection data obtained from the converting unit and the overflow digital projection data obtained from the overflow detecting unit; andweighting and combining an output obtained from the first fitting unit and an output obtained from the second fitting unit with a weighting unit to output a correction of the digital projection data,wherein a weight is adaptatively calculated by simulation by the weighting unit based on prior known digital projection data of the x-ray computed tomography system or the weight is obtained from a known lookup table. 20. The method of claim 17, further comprising:reconstructing the image of the object with a reconstruction unit, based on the corrected digital projection data and non-overflow digital projection data obtained from the correction unit and the converting unit, respectively. 21. The method of claim 20, further comprising:displaying the image of the object reconstructed by the reconstruction unit on a display unit. 22. The method of claim 19, wherein the correcting further comprises:identifying overflow points in the digital projection data obtained from the converting unit with a linear interpolation unit; andlinearly interpolating a group of overflow points identified by the linear interpolation unit if the group has a number of overflow points smaller than a predetermined number. 23. The method of claim 22, wherein the first and second fitting units correct only groups of overflow points that have a number of overflow points bigger than the predetermined number. 24. The method of claim 23, wherein the predetermined number is one. 25. The method of claim 17, wherein the x-ray detector is an array detector having a plurality of detector elements. 26. The method of claim 22, further comprising:creating an overflow map that identifies overflow points in the digital projection data obtained from the converting unit with an overflow map unit; andproviding the overflow map to the correction unit. 27. The method of claim 26, further comprising:inputting prior known digital projection data of the x-ray computed tomography system into a prior knowledge input unit; andproviding the prior known digital projection data to the weighting unit. 28. The method of claim 27, wherein the prior known digital projection data is water calibration data obtained by irradiating water with the x-ray beam in the computed tomography system and measuring with the x-ray detector the at least one characteristic of the x-ray beam, after the x-ray beam has passed through the water. 29. The method of claim 28, further comprising:calculating a correction of the overflow digital projection data with a prior knowledge correction unit based on an output obtained from the prior knowledge input data unit and an output obtained from the weighting unit; andselecting a best correction to be applied to the digital projection data based on an output obtained from the correction unit and an output obtained from the prior knowledge correction unit by using a selection unit that communicates to the correction unit and the prior knowledge correction unit. 30. The method of claim 29, whereinthe first curve fitting function is a spline function,the second curve fitting function is a polynomial function, andthe selection unit selects the smallest correction from the correction of the weighting unit, a correction of the second fitting unit, and the correction of the prior knowledge correction unit as the best selection. 31. The method of claim 17, wherein the correcting comprises:selecting a correction method based on characteristics of the overflow with a selection unit connected to the correction unit. 32. The method of claim 17, wherein the correcting comprises:correcting the digital projection data along a channel direction of the x-ray detector. 33. A computer readable medium for correcting an image of an object placed in an x-ray computed tomography system that generates an x-ray beam with an x-ray generator and detects with an x-ray detector at least one characteristic of the x-ray beam generated by the x-ray generator, after the x-ray beam has passed through the object, the computer readable medium storing instructions for execution on a computer system, which when executed by the computer cause the computer to execute a process comprising:converting analog projection data outputted by the x-ray detector to digital projection data with a converting unit connected to the x-ray detector;detecting overflow digital projection data that overflows a measuring range of the computed tomography system with an overflow detecting unit connected to the converting unit; andcorrecting the overflow digital projection data with a correction unit connected to the overflow detecting unit by using a curve fitting function to produce the corrected image. 34. The computer readable medium according to claim 33, wherein the correcting comprises:correcting the overflow digital projection data with the correction unit based on the overflow digital projection data obtained from the overflow detecting unit, non-overflow digital projection data of the digital projection data obtained from the converting unit, and the curve fitting function. 35. The computer readable medium according to claim 34, wherein the correcting further comprises:performing a first curve fitting function with a first fitting unit on the non-overflow digital projection data obtained from the converting unit;performing a second curve fitting function with a second fitting unit on a combination of the non-overflow digital projection data obtained from the converting unit and the overflow digital projection data obtained from the overflow detecting unit; andweighting and combining an output obtained from the first fitting unit and an output obtained from the second fitting unit with a weighting unit to output a correction of the digital projection data,wherein a weight is adaptatively calculated by simulation by the weighting unit based on prior known digital projection data of the x-ray computed tomography system or the weight is obtained from a known lookup table. 36. The computer readable medium according to claim 33, further comprising:reconstructing the image of the object with a reconstruction unit, based on the corrected digital projection data and non-overflow digital projection data obtained obtained from the correction unit and the converting unit, respectively. 37. The computer readable medium according to claim 33, further comprising:displaying the image of the object reconstructed by the reconstruction unit on a display unit. 38. The computer readable medium according to claim 35, wherein the correcting further comprises:identifying overflow points in the digital projection data obtained from the converting unit with a linear interpolation unit; andlinearly interpolating a group of overflow points identified by the linear interpolation unit if the group has a number of overflow points smaller than a predetermined number. 39. The computer program product according to claim 38, wherein the first and second fitting units correct only groups of overflow points that have a number of overflow points bigger than the predetermined number. 40. The method of claim 39, wherein the predetermined number is one. 41. The computer readable medium according to claim 33, wherein the x-ray detector is an array detector having a plurality of detector elements. 42. The computer readable medium according to claim 38, further comprising:creating an overflow map that identifies overflow points in the digital projection data with an overflow map unit; andproviding the overflow map to the correction unit. 43. The computer readable medium according to claim 42, further comprising:inputting prior known digital projection data of the x-ray computed tomography system into a prior knowledge input unit; andproviding the prior known digital projection data to the weighting unit. 44. The computer readable medium according to claim 43, wherein the prior known digital projection data is water calibration data obtained by irradiating water with the x-ray beam in the computed tomography system and measuring with the x-ray detector the at least one characteristic of the x-ray beam, after the x-ray beam has passed through the water. 45. The computer readable medium according to claim 44, further comprising:calculating a correction of the overflow digital projection data with a prior knowledge correction unit based on an output obtained from the prior knowledge input data unit and an output obtained from the weighting unit; andselecting a best correction to be applied to the digital projection data based on an output obtained from the correction unit and an output obtained from the prior knowledge correction unit by using a selection unit that communicates to the correction unit and the prior knowledge correction unit. 46. The computer readable medium according to claim 45, whereinthe first curve fitting function is a spline function,the second curve fitting function is a polynomial function, andthe selection unit selects the smallest correction from the correction of the weighting unit, a correction of the second fitting unit, and the correction of the prior knowledge correction unit as the best selection. 47. The computer readable medium according to claim 33, wherein the correcting comprises:selecting a correction method based on characteristics of the overflow with a selection unit connected to the correction unit. 48. The computer readable medium according to claim 33, wherein the correcting comprises:correcting the digital projection data along a channel direction of the x-ray detector. |
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summary | ||
abstract | A package (100) comprising storage packaging (1) as well as a confinement canister (3) for irradiated fuel, the packaging comprising a lateral body (2) which extends around a longitudinal axis (12) of the packaging and which includes an internal surface (22) which delimits a cavity for housing the canister (3), the packaging furthermore comprising at least one assembly (15) forming a guide rail for the canister in the cavity, mounted on the lateral body (2) and protruding at least partly into the housing cavity (4). According to the invention, the assembly forming a guide rail (15) includes an impact shock absorbing element (28) designed to absorb the shock, by plastic deformation, of a lateral impact between the packaging (1) and the confinement canister (3). |
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abstract | The invention proposes a zirconium-based alloy also containing, by weight, apart from unavoidable impurities, from 0.02 to 1% of iron, from 0.8% to 2.3% of niobium, less than 2000 ppm of tin, less than 2000 ppm of oxygen, less than 80 ppm of carbon, from 5 to 35 ppm of sulphur and less than 0.25% in total of chromium and/or vanadium, the ratio R of the niobium content less 0.5% to the iron content, optionally supplemented by the chromium and/or vanadium content, being lower than 3. |
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053918878 | claims | 1. A container system for storing hazardous waste material, comprising: a cylindrical body consisting of precipitation hardenable material, said body having an open top and a closed bottom; a lid consisting of precipitation hardenable material; a channel for receiving weld filler material having a precipitation hardening temperature lower than the temperature where significant aging kinetics are triggered in the material of said body and said lid, said channel being formed between said lid and said body with said lid secured to the top portion of said body, thereby sealing off said container, said channel being circumferential about said container for receiving said weld filler material. means for heat treating said weld filler material for precipitation hardening thereof to substantially attain the same mechanical, electrical, and thermal characteristics of said weld filler material as the material of said body and said lid. a housing having a cylindrical shape, a closed top, and an open bottom, the inside diameter of said housing being greater than the outside diameter of said lid and said body of said container; a band-like heater affixed to a portion of the circumference about the inside surface of a sidewall of said housing, the heater being positioned therein to provide that it is centered upon the weld filler material of said weld channel when said housing is installed over a top portion of said container, for heat treating the weld filler material; and cooling means for cooling the material of said lid and said body above and below said weld filler material within said channel, at times of heat treating said weld filler material. first cooling tubes affixed to the inside surface of the top of said housing, said first cooling tubes being arranged for contacting the top of said lid when said housing is mounted over the top of said container, whereby coolant is passed through said tubes for conducting heat away from said lid generated therein during heat treatment of said weld filler material; and second cooling tubes affixed to the interior portion of a sidewall of said housing below said heater, whereby coolant is passed through said second cooling tubes for cooling portions of said container below and proximate said weld filler material as it is being heat treated. a bottom portion of the sidewall of said container below said cooling means being of reduced diameter for causing that portion to fit snugly against the sidewall of said body when said housing is mounted over said container; and a manually adjustable securing band being mounted around the outside of the lower reduced diameter portion of said housing, for tightening this portion against the opposing sidewall portion of said container, thereby securing said heat treating apparatus in place on said container. a plurality of transducers mounted upon and through said housing at predetermined positions for contacting predetermined points on said lid whenever said housing is mounted onto said container, for providing a measurement of the temperature at these various contact points during the heat treating process. a laminated disk including a first layer of material for providing a bearing surface to prevent galling of an underlying second layer of material by rotational movement of the bottom of said lid as it is screwed into said body, and a third layer of material affixed to said second layer for providing rigidity to said laminated disk; said shoulder including first and second circular ridges concentric with one another and spaced apart; and said first and second layers of material each having a diameter slightly less than the maximum diameter associated with said shoulder, and said third layer having a diameter slightly less than the minimum diameter of said shoulder equivalent to the diameter of an inside wall of said body below said shoulder, whereby as said lid is screwed into said body, the bottom of said lid forces an outer exposed portion of said second layer of material into compression against said first and second ridges, causing plastic deformation of said second layer of material about said first and second ridges, thereby providing multiple ring seals therebetween. a metal disk having a top side and a bottom side; and two concentric metal "O"-rings affixed to the bottom side of said disk, whereby when said lid is secured to the top of said body, the bottom of said lid is torqued against the top side of said disk for compressing said metal "O"-rings to flatten them against said shoulder for providing a double "O"-ring seal therebetween. a metallic disk of temperature deformable material; and a circumferential groove located in an inside wall portion of said body between said shoulder and said inside wall of said top portion of said body, wherein said metallic disk is secured between the bottom of said lid and said shoulder with said lid secured to the top of said body, whereafter said metallic disk is heated via an external heat source for triggering expansion of said disk into said circumferential groove. three radially directed slots cut or formed into the top of said dome shaped portion from the circumference thereof, directed inward for a predetermined distance, with each slot being terminated via a back wall thereof, respectively; and three radially directed holes from the lower center of the back walls of said slots, respectively, for a predetermined distance toward the center of said lid, said slots and associated holes providing for receipt of portions of said handling apparatus. three radially directed holes through a sidewall of said cup-shaped portion, said holes being equally spaced from one another, said holes providing for receipt of manipulating apparatus for installing and removing said lid to said body, and for lifting said container via said lid. a cup-shaped x-ray film insert dimensioned to frictionally fit within a lower interior portion of said cup-shaped portion of said lid, said insert including a band-like shallow channel about the outside circumference of a lower sidewall portion, said channel being adapted for receiving a strip of x-ray film, and holding the film in place between said insert and a circumferential portion of an inside wall of said cup-shaped portion of said lid opposite said channel formed between said lid and said top rim of said body for receiving weld filler material, whereby inspection of a resultant weld is facilitated by transmitting x-rays through the weld and sidewall portion of said cup lid, for exposing said film to permit inspection of said weld. a cylindrical body; a lid shaped to include an upper dome-like portion, and a lower threaded portion of reduced diameter relative to the upper portion, for mating with a threaded interior portion of said body proximate a top rim thereof; said lid further including manipulating means on a top portion of said dome-like portion thereof, for coacting with apparatus for installing or removing said lid from said body, and for lifting said container by said lid; a channel for receiving weld filler material, said channel being formed from a lower edge portion of said dome shaped portion of said lid, and a top portion of said top rim of said body, with said lid and body mated together wherein said body, said lid and said weld filler material consist of precipitation hardenable alloy material; and sealing means positioned between the bottom of said lid as mated to said body and a shoulder formed within said body immediately below said interior threaded portion thereof, said sealing means providing a vacuum seal between said container and said lid. means for heat treating said weld filler material for precipitation hardening thereof to substantially attain the same mechanical, electrical, and thermal characteristics of said weld filler material as the material of said body and said lid. three radially directed slots cut or formed into the top of said dome shaped portion from the circumference thereof, directed inward for a predetermined distance, with each slot being terminated via a back wall thereof, respectively; and three radially directed holes from the lower center of the back walls of said slots, respectively, for a predetermined distance toward the center of said lid, said slots and associated holes providing for receipt of portions of said handling apparatus. a metal disk having a top side and a bottom side; two concentric metal "O"-rings affixed to the bottom side of said disk, whereby when said lid is screwed into said body, the bottom of said lid is torqued against the top side of said disk for compressing said metal "O"-rings to flatten them against said shoulder for providing a double "O"-ring seal therebetween. a metallic disk of temperature deformable material; and a circumferential groove located in an inside wall portion of said body between said shoulder and said threads thereof, wherein said metallic disk is secured between the bottom of said lid and said shoulder with said lid screwed in place, whereafter said metallic disk is heated via an external heat source for triggering expansion of said disk into said circumferential groove. a laminated disk including a first layer of material for providing a bearing surface to prevent galling of an underlying second layer of material by rotational movement of the bottom of said lid as it is screwed into said body, and a third layer of material affixed to said second layer for providing rigidity to said laminated disk; said shoulder including first and second circular ridges concentric with one another and spaced apart; and said first and second layers of material each having a diameter slightly less than the maximum diameter associated with said shoulder, and said third layer having a diameter slightly less than the minimum diameter of said shoulder equivalent to the diameter of an inside wall of said body below said shoulder, whereby as said lid is screwed into said body, the bottom of said lid forces an outer exposed portion of said second layer of material into compression against said first and second ridges, causing plastic deformation of said second layer of material about said first and second ridges, thereby providing multiple ring seals therebetween. a cylindrical body; a lid shaped to include an upper cup-shaped portion, and a lower threaded portion of reduced diameter, for mating with a threaded interior portion of said body proximate a top rim thereof, for configuring said container for providing long term storage of hazardous waste material; said cup-shaped portion of said lid including manipulating means formed therein for coacting with handling apparatus, for installing or removing said lid from said body, and for lifting said container by said lid; a channel for receiving weld filler material, said channel being formed from a lower edge portion of said cup-shaped portion of said lid, and a top portion of said top rim of said body, with said lid and body mated together wherein said body, said lid and said weld filler material consist of precipitation hardenable alloy material; and sealing means positioned between the bottom of said lid as mated to said body and a shoulder formed within said body immediately below said interior threaded portion thereof, said sealing means providing a vacuum seal between said container and said lid. a metal disk having a top side and a bottom side; two concentric metal "O"-rings affixed to the bottom side of said disk, whereby when said lid is screwed into said body, the bottom of said lid is torqued against the top side of said disk for compressing said metal "O"-rings to flatten them against said shoulder for providing a double "O"-ring seal therebetween. means for heat treating said weld filler material for precipitation hardening thereof to substantially attain the same mechanical, electrical, and thermal characteristics of said weld filler material as the material of said body and said lid. three radially directed holes through a sidewall of said cup-shaped portion, said holes being equally spaced from one another, said holes providing for receipt of manipulating apparatus for installing and removing said lid to said body, and for lifting said container via said lid. a metallic disk of temperature deformable material; and a circumferential groove located in an inside wall portion of said body between said shoulder and said threads thereof, wherein said metallic disk is secured between the bottom of said lid and said shoulder with said lid screwed in place, whereafter said metallic disk is heated via an external heat source for triggering expansion of said disk into said circumferential groove. a laminated disk including a first layer of material for providing a bearing surface to prevent galling of an underlying second layer of material by rotational movement of the bottom of said lid as it is screwed into said body, and a third layer of material affixed to said second layer for providing rigidity to said laminated disk; said shoulder including first and second circular ridges concentric with one another and spaced apart; and said first and second layers of material each having a diameter slightly less than the maximum diameter associated with said shoulder, and said third layer having a diameter slightly less than the minimum diameter of said shoulder equivalent to the diameter of an inside wall of said body below said shoulder, whereby as said lid is screwed into said body, the bottom of said lid forces an outer exposed portion of said second layer of material into compression against said first and second ridges, causing plastic deformation of said second layer of material about said first and second ridges, thereby providing multiple ring seals therebetween. 2. The container system of claim 1, further including: 3. The container system of claim 2, wherein said heat treating means includes: 4. The container system of claim 3, wherein said cooling means includes: 5. The container system of claim 3, further including: 6. The container system of claim 5, wherein said heat treating means further includes said housing having a lowermost outwardly flaring sidewall portion below said region of reduced diameter, for assisting in centering said housing onto the top of said container, during installation of said heat treating means upon said container. 7. The container system of claim 3, wherein said heat treating means further includes: 8. The container system of claim 7, wherein said transducers are spring-loaded thermocouples. 9. The container system of claim 3, further including a lifting bracket rigidly attached to the top surface of the top of said housing. 10. The container system of claim 1, wherein the material of said body, lid, and weld filler consists of copper beryllium alloy. 11. The container system of claim 1, wherein the material of said body and said lid consists of C17510 beryllium-copper alloy. 12. The container system of claim 11, wherein said weld filler material consists of C17200 copper-beryllium alloy. 13. The container system of claim 1, further including sealing means between the bottom of said lid, and a shoulder formed within said body below an open top portion thereof configured for receiving said lid, said sealing means providing a mechanical vacuum seal between said container and said lid. 14. The container system of claim 13, wherein said lid includes a lower threaded portion, and said body includes an interior threaded portion above said shoulder for mating with the threads of said lid, thereby permitting said lid to be screwed into said body. 15. The container system of claim 14, further including sealing means between the bottom of said lid, and a shoulder formed within said body below said open top portion thereof configured for receiving said lid, said sealing means providing a mechanical vacuum seal between said container and said lid, said sealing means including: 16. The container system of claim 15, wherein said first layer of material consists of UNS7718 material, said second layer consists of C10700 material, and said third layer consists of UNS7718 material. 17. The container system of claim 13, wherein said sealing means includes: 18. The container system of claim 17, wherein said "O"-rings are welded to the bottom side of said metal disk. 19. The container system of claim 13, wherein said sealing means includes: 20. The container system of claim 19, wherein said metallic disk consists of NiTi material. 21. The container system of claim 19, wherein said disk is dimensioned for upon expansion via heat triggering, expanding to form a first ring seal about an interior circumferential portion of said shoulder, and a second ring seal with a circumferential corner edge between said groove and the inside sidewall of said body. 22. The container system of claim 1, wherein a top portion of said lid includes means formed thereon for coacting with handling apparatus, for installing or removing said lid from said body, and for lifting said container by said lid. 23. The container system of claim 1, wherein said lid is shaped to include an upper dome-like portion, and a lower threaded portion of reduced diameter relative to the upper portion, for mating with a threaded interior portion of said body proximate a top rim thereof. 24. The container system of claim 23, wherein a top portion of said dome-like portion of said lid includes manipulating means formed therein for coacting with handling apparatus, for installing or removing said lid from said body, and for lifting said container by said lid. 25. The container system of claim 24, wherein said manipulating means of said lid further includes: 26. The container system of claim 23, wherein said lid further includes a lower edge of said dome-shaped portion being formed to provide in combination with said top rim of said body, said channel for receiving said weld filler material. 27. The container system of claim 1, wherein said lid is shaped to include an upper cup-shaped portion, and a lower threaded portion of reduced diameter, for mating with a threaded interior portion of said body proximate a top rim thereof, for configuring said container for providing long term storage of hazardous waste material. 28. The container system of claim 27, wherein said cup-shaped portion of said lid includes manipulating means formed therein for coacting with handling apparatus, for installing or removing said lid from said body, and for lifting said container by said lid. 29. The container system of claim 28, wherein said manipulating means of said lid further includes: 30. The container system of claim 27, further including: 31. The container system of claim 27, wherein said lid further includes indexing and calibrating means on said cup-shaped portion for permitting an inspection tool mounted thereon to determine its angular position at any time to determine the location of defects in a weld in said channel. 32. The container system of claim 27, wherein said lid further includes a lower edge of said cup-shaped portion thereof being formed to provide in combination with said top rim of said body, said channel for receiving said weld filler material. 33. The container system of claim 1, wherein the depth of said channel for receiving said weld filler material is predetermined for receiving a continuous weld bead deposited in five passes about the circumference of said channel, the five passes consisting of root, first fill, second fill, third fill, and capping weld passes, respectively. 34. A container for the storage of hazardous waste material, including nuclear waste material, for periods of time of about forty years, said container comprising: 35. The container of claim 34, wherein said weld filler material has a precipitation hardening temperature lower than the temperature where significant aging kinetics are triggered in the material of said body and said lid. 36. The container of claim 34, wherein said body and said lid each consist of C17510 beryllium-copper alloy, and said weld filler material consists of C17200 copper-beryllium alloy. 37. The container of claim 36, further including: 38. The container of claim 34, wherein said manipulating means of said lid includes: 39. The container of claim 34, wherein said sealing means includes: 40. The container of claim 34, wherein said sealing means includes: 41. The container of claim 34, wherein said sealing means includes: 42. The container of claim 41, wherein said first layer of material consists of UNS7718 material, said second layer consists of C10700 material, and said third layer consists of UNS7718 material. 43. A container for storing hazardous waste material, including nuclear waste material, for periods of time exceeding hundreds of years, comprising: 44. The container of claim 43, wherein said weld filler material has a precipitation hardening temperature lower than the temperature where significant aging kinetics are triggered in the material of said body and said lid. 45. The container of claim 43, wherein said sealing means includes: 46. The container of claim 43, wherein said body and said lid each consist of C17510 beryllium-copper alloy, and said weld filler material consists of C17200 copper-beryllium alloy. 47. The container of claim 43, further including: 48. The container of claim 43, wherein said manipulating means of said lid further includes: 49. The container of claim 43, wherein said sealing means includes: 50. The container of claim 43, wherein said sealing means includes: 51. The container of claim 50, wherein said first layer of material consists of UNS7718 material, said second layer consists of C10700 material, and said third layer consists of UNS7718 material. |
050864440 | abstract | A primary radiation diaphragm for use in a medical radiation application apparatus for gating the x-ray beam emitted by a radiation source onto a desired region has first and second diaphragm plates and an actuator for the diaphragm plates having two ranges of adjustment. The first diaphragm plate is adjusted within the first range of adjustment by movement of the actuator, and the second diaphragm rate is adjusted by moving the actuator within the second range of adjustment. |
055352502 | claims | 1. A device for manipulating a synchrotron beam bundle, in irradiating apparatuses for deep X-ray lithography containing within a vacuum chamber an object table for receiving an object to be irradiated, comprising: a vacuum chamber having a window for allowing a synchrotron beam bundle to enter said chamber; an object table disposed within said vacuum chamber for receiving an object to be irradiated, said object being adjustable by a scanning movement relative to said synchrotron beam bundle; a filter chamber connected upstream of the vacuum chamber and containing filters which can be inserted into the synchrotron beam bundle; pairs of diaphragms which are displaceable relative to one another being provided between said object table and said window and adjacent to said filter chamber; and wherein a pair of said pairs of diaphragms for which the direction of relative displacement of the diaphragms coincides with the scanning movement is coupled with the scanning movement. 2. The device according to claim 1, wherein filter changers are provided for inserting the filters into the synchrotron beam bundle, wherein a pneumatic cylinder is fastened via stay rods to a vacuum flange arranged on the filter chamber, and wherein movement of the pneumatic cylinder is transmitted to a connecting rod by means of a rod linkage which passes within a guide bush and membrane bellows, a filter holder being fastened to the connecting rod. 3. The device according to claim 2, wherein the filter holder has two frame members which are provided with an elongated aperture adapted to the cross section of the synchrotron beam bundle. 4. The device according to claim 1, wherein one pair of diaphragms which are displaceable relative to one another forms a first beam limiting unit which limits the synchrotron beam bundle horizontally. 5. The device according to claim 4, wherein there is in the beam limiting unit, for each of the diaphragms which are displaceable relative to one another, a guide rail which is rigidly supported on a mounting plate and a spindle which is rotatably supported on the mounting plate via holding elements, and wherein a spindle nut which is fixed relative to rotation on the spindle carries one of the diaphragms, and wherein sensors, which are fastened to the mounting plate, are provided for positioning the diaphragms. 6. The device according to claim 4, wherein the other pair of diaphragms which are displaceable relative to one another forms a second beam limiting unit which limits the synchrotron beam bundle vertically and in which the displacement of the diaphragms is carried out by driving elements which substantially correspond to those provided for driving diaphragms and are fastened to the movable part of the object table. |
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abstract | The invention relates to a method of producing radionuclides. According to the method, a target medium comprising at least a target nuclide material is irradiated in an irradiation zone with neutron irradiation. Radionuclides form in the target nuclide material as a result of the irradiation, and at least some of the formed radionuclides are ejected from the target nuclide material. The ejected radionuclides are then captured and collected in a carbon-based recoil capture material which does not have an empty cage structure at crystallographic level. |
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050283847 | abstract | A measure providing improved personnel safety in the operation of a steam producing, water cooled, boiling water nuclear fission reactor for generating electrical power is disclosed. The measure comprises utilizing catalytic oxidation to inhibit the escape of certain radioactive material from the reactor and its passage through the steam circuit. |
abstract | A channel type heterogeneous reactor core for a heavy water reactor for burnup of thorium based fuel is provided. The heterogeneous reactor core comprises at least one seed fuel channel region comprising seed fuel channels for receiving seed fuel bundles of thorium based fuel; and at least one blanket fuel channel region comprising blanket fuel channels for receiving blanket fuel bundles of thorium based fuel; wherein the seed fuel bundles have a higher percentage content of fissile fuel than the blanket fuel bundles. The seed fuel channel region and the blanket fuel channel region may be set out in a checkerboard pattern or an annular pattern within the heterogeneous reactor core. Fuel bundles for the core are also provided. |
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040640019 | abstract | A system is provided for the relief of excess pressure from the hot leg of a nuclear reactor to the cold leg on the occurrence of a loss of coolant accident. This system includes a conduit connecting the hot leg with the cold leg. The conduit further includes a check valve which is operated on the basis of differential pressure so that during normal operation the valve is closed. |
description | This application is a U.S. National Phase Application under 35 U.S.C. § 371 of International Patent Application No. PCT/FR2016/052881, filed Nov. 7, 2016, and claims the benefit of priority under 35 U.S.C. Section 119(e) of French Application Serial No. 1560606, filed Nov. 5, 2015, all of which are incorporated by reference in their entireties. The International Application was published on May 11, 2017 as International Publication No. WO 2017/077259 A1. This invention relates to a radiation protection screen. Typically, a radiation protection screen is used to separate a person from an element emitting ionizing rays, and to protect that person from these rays. For this purpose, a radioprotection screen includes a panel coated with a radiation protection sheet (typically a leaded sheet). However, the rigidity of the screen comes only from the panel, and nothing can be fixed to it so as not to perforate the radiation protection sheet. In addition, in the case of mobile screen, there is no radiological protection at the wheels whose height is generally equal to about 15 cm. The invention aims to solve the aforementioned problems, and in particular to allow the attachment of an object to the screen without altering the radiation protection sheet. According to the invention, the radiation protection screen comprises two main faces, characterized in that it comprises a framework which stiffens the screen and which carries on each side a panel, one of the panels being radiation protective. Therefore, the screen according to this invention comprises a rigid framework which carries, on one side, a radiation protective panel and, on the other side, a panel which can be secured to an object by fixing the object to the framework. Typically, the thickness of the framework is about 5 cm. According to a first embodiment, the frame is formed by a section assembly. As a result, the structure of the framework is particularly light. By “section”, one means in particular a longitudinal structure preferably open along the longitudinal axis, such as a structure having a section “U”, “L” or “V.” The assembled sections are connected together to form the framework stiffening the screen. More particularly, the framework comprises external sections and internal sections, said sections covering at least the internal sections. According to a first variant of the first embodiment, each section is made of stainless steel. As a result, the framework is made of stainless steel. According to a second variant of the first embodiment, each section has a generally U-shaped form, each side panel carries a side of the screen. Therefore, knowing the position of the sections, it is possible that the object is attached to the side panel that supports the non-radiation protective side. According to a third variant of the first embodiment, the section assembly comprises an outer frame forming the outer limits of the screen. According to a first preference of the third variant of the first embodiment, when the sections forming the outer frame have a generally U-shaped form, they are oriented so that the central branch of the U is disposed on the inside of the screen. As a result, the edge of the outer frame is formed by the opening of the U. According to a second preference of the third variant of the first embodiment, the section assembly comprises at least one horizontal section which extends from one to the other of the two vertical sections of the outer frame. Advantageously, the section assembly comprises two parallel vertical sections which extend between two adjacent horizontal sections. As a result, the two adjacent horizontal sections and the two parallel vertical sections define a rectangular frame in the framework. According to a second embodiment, the non-radiation protective panel comprises an inner panel fixed to the framework and an outer panel covering the inner panel. Typically, the thickness of the inner panel is about 12 to 16 mm, and that of the outer panel is about 1 to 2 mm. According to a first variant of the second embodiment, the inner panel is a chipboard, preferably chipboard having good moisture behavior (CTBH). According to a second variant of the second embodiment, the outer panel is a laminated panel. The laminate panel can be colored. According to a third variant of the second embodiment, the radiation protective panel comprises a lead sheet (typically of a thickness of 1 to 2 mm) attached to the framework and a non-radiation protective panel attached to the lead sheet. Thus, the radiation protective panel includes the lead sheet that is attached to the framework, an inner panel that is attached to the lead sheet, and an outer panel that is attached to the inner panel. By its arrangement, the lead sheet provides radiation protection of the radiation protective panel. According to a third embodiment, the radioprotection screen includes a radiation protection glazing. Typically, the radiation protection glazing is a so-called leaded glazing. Therefore, each panel includes an opening in which is disposed the radiation protection glazing. According to a first variant of the third embodiment, the radiation protection glazing is surrounded by the two parallel vertical sections and the two adjacent horizontal sections of the advantageous mode of the second preference of the third variant of the first embodiment. According to a second variant of the third embodiment, the radioprotection screen comprises two glazing beads, each glazing bead being disposed at the junction of the radiation protection glazing with the panels. According to a first advantage of the second variant of the third embodiment, a first glazing bead has an L-shaped cross section, one branch of which covers the peripheral edge of the opening of one panel and the other branch bears on the framework. According to a second advantage of the second variant of the third embodiment, a second glazing bead in the form of a simple box covering the peripheral edges of the radiation protection glazing and the opening of a panel. According to an advantageous embodiment of the second advantage of the second variant of the third embodiment, the second windscreen covers an additional radiation protection sheet which extends into a peripheral groove formed in the radiation protective panel and which covers the peripheral rim of the radiation protection glazing, also arranged in that groove. Preferably, the second glazing bead is fixed (by screwing) to a portion of the panel that surrounds the peripheral groove. According to a third advantage of the second variant of the third embodiment, the glazing beads are made of aluminum. According to a fourth embodiment, the radiation protection screen comprises wheels allowing its displacement. According to a first variant of the fourth embodiment, the wheels are pivoting with respect to a vertical axis. As a result, the change of orientation of the screen is facilitated. According to a second variant of the fourth embodiment, the screen comprises a base which surrounds the wheels. According to a first advantage of the second variant of the fourth embodiment, a radiation protection film (typically a lead film) is secured to the base in order to ensure, at the level of the wheels, the continuity of the radiation protection carried out by the radiation protective panel. According to a second advantage of the second variant of the fourth embodiment, the base comprises an upper wall which is connected to the framework, and four side walls which hang from the upper wall and which surround the wheels. Typically, the sidewalls extend from the top wall to a distance close to the ground on which the wheels rest (about 1 cm from the ground). In addition, unlike a protection panel at the wheels, a protection by a base allows to limit the diffuse rays that can be reflected on the ground just below the panel. According to a first preference of the second advantage of the second variant of the fourth embodiment, the radiation protection film extends, firstly, along the portion of the upper wall which extends on the side of the front face, and, on the other hand, along the side wall which is also located on the side of the front face. According to a second preference of the second advantage of the second variant of the fourth embodiment, the upper wall and the four side walls are made of stainless steel. According to a third preference of the second advantage of the second variant of the fourth embodiment, a skirting board connects the base to the framework in a fixed manner. Advantageously, the skirting board is integral with the base and extends vertically upwards. According to a third variant of the fourth embodiment, the screen comprises a handle to facilitate its grip and its movement. Advantageously, the handle is hollowed in a side edge of the screen. According to a fifth embodiment, the screen comprises a skirting board which is fixed to the framework and which is adapted to be fixed to a floor. Advantageously, the skirting board is made of stainless steel in order to withstand the possible shocks that it could undergo once the screen has been installed. According to a sixth embodiment, the screen comprises a peripheral covering which forms its outer limit. According to a first variant of the sixth embodiment, the peripheral casing covers the outer peripheral edge of the two sections of the screen. According to a second variant of the sixth embodiment, the peripheral casing with a generally U-shaped form, each side branch of which covers the outer peripheral edge of a panel and whose central branch forms the corresponding edge of the screen. According to a third variant of the sixth embodiment, the peripheral casing is made of aluminum. According to the seventh embodiment, the panel which is not radiation protective carries a tablet attached to the frame. Advantageously, the tablet comprises a fixed part fixed to the frame and a movable part articulated to the fixed part. FIGS. 1 and 3 show in perspective two examples of radiation protection screen 1 according to this invention. Each radiation protection screen 1 comprises two main faces 2, 3: a front face 2 intended to be on the source side emitting ionizing radiation, and a rear face 3 intended to be on the side of the people to protect from the ionizing radiation. According to the invention, the radiation protection screen 1 comprises a framework 4 which stiffens it and which carries a front panel 5 on the side of the front panel 2, and a rear panel 6 on the side of the rear panel 3. Here, the front panel 5 is a radiation protective panel and the rear panel 6 is a non-radiation protective panel. In the present examples, each radiation protection screen 1 has a height of 2 meters and a width of 0.8 meters, and the distance between the front face 2 of the rear face 3 is 72 millimeters. The radiation protective panel 5 is formed by a radiation protection sheet 7 (typically a leaded sheet) which is attached to framework 4 and a non-radiation protective panel 8 (typically the same panel as the rear panel 6) which is attached to the radiation protection sheet 7. The thickness of the radiation protection sheet 7 is approximately 1 to 2 millimeters. The non-radiation protective rear panel 6 and the non-radiation protective panel 8 forming part of the front radiation protective panel 5 comprise an inner panel and an outer panel. The inner panel is attached to the lead sheet 7 (in the case of the radiation protective front panel 5) or to framework 4 (in the case of the non-radiation protective rear panel 6). The outer panel covers the inner panel. Typically, the inner panel is a chipboard (preferably chipboard with good moisture behavior) and its thickness is about 12 to 16 millimeters. Typically, the outer panel is a laminated panel and its thickness is about 1 to 2 millimeters. Framework 4 is 12-tenths stainless steel and is formed by an assembly of sections 9, 10, 11, 12, 13 which gives strength and lightness to the radiation protection screen 1 (each section is made of stainless steel). Framework 4 is 12-tenths stainless steel and is formed by an assembly of sections 9, 10, 11, 12, 13 which gives strength and lightness to the radioprotection screen 1 (each section is made of stainless steel). In particular, framework 4 comprises external sections 9, 10, 11 and internal sections 12, 13. Sections 5, 6 cover at least internal sections 12, 13. Preferably, the internal sections are arranged between sections 5, 6. Each section 9, 10, 11, 12, 13 has a generally U-shaped form, of which each side panel carries a panel 5, 6. Here, the width of each side panel is about 20 millimeters and the width of the central branch is about 50 millimeters. Section 9, 10, 11, 12, 13 assembly comprises a rectangular outer frame forming the outer boundaries of the radiation protection screen 1. In this case, this outer frame comprises two vertical sections 9 and two horizontal sections 10, 11 connecting the two vertical sections 9 (an upper horizontal section 10 located near the upper ends of the two vertical sections 9, and a lower horizontal section 11 disposed near the lower ends of the two vertical sections 9). Here, vertical sections 9 of the outer frame have a U-shaped form, each lateral branch 14 carrying a wheelbase 15 which is parallel to the central branch 16 and which is directed opposite the other lateral branch 14. The central branch 16 is disposed on the inside of the radiation protection screen 1 and, therefore, the edge of the outer frame is formed by the opening of the U. Each wheelbase 15 has a width of about 10 millimeters. Section 9, 10, 11, 12, 13 assembly also comprises at least one internal horizontal section 12 which extends from one to the other of the two vertical sections 9 of the outer frame (here, four internal horizontal sections 12). In the present examples, the central branch of the U of all the horizontal sections 10, 11, 12 (including those of the outer frame) is formed by two horizontal walls which are in line with one another so as to form the major part of the central branch, the two horizontal walls being connected to each other by a central U-shaped connecting segment. The central U-shaped segment comprises a central branch and two lateral branches. The central branch of the U-shaped central link segment is parallel to the two horizontal walls which form the major part of the central branch of horizontal section 10, 11, 12 in U. The two lateral branches of the central link segment are parallel to each other and with the two lateral branches of horizontal section 10, 11, 12 in U. Each horizontal wall carries at one end a lateral branch of horizontal section 10, 11, 12 U which extends in a first direction, and at a second end a lateral branch of the central connecting segment which extends in a second direction opposite to the first direction. The assembly of sections 9, 10, 11, 12, 13 also comprises two parallel internal vertical sections 13 which extend between two adjacent internal horizontal sections 12. In the present examples, the two internal vertical sections 13 have a U-shape and have, at each of their longitudinal end, a connecting wall which is carried by the central branch of the internal vertical section 13 and which is oriented in the opposite direction to that of the lateral branches of the inner vertical section 13. The two connecting walls of the two internal vertical sections 13 allow to fix these two sections 13 to two adjacent internal horizontal sections 12. As a result, the two adjacent internal horizontal sections 12 and the two internal vertical sections 13 define a rectangular frame in framework 4. Panels 5, 6 (more precisely the inner panels of panels 5, 6) are attached to the lateral branches of the sections of framework 4 and their edges (more precisely the edges of the inner and outer panels and the radiation protection sheet 7 of sections 5, 6) abut against the wheelbases 15 of the two vertical sections 9 of the outer frame of framework 4. Radiation protection screen 1 comprises a radiation protection glazing 17. Typically, this radiation protection glazing 17 is a so-called leaded glazing. It has a thickness of 8.5 millimeters (corresponding to a thickness of 2.2 millimeters of lead equivalent). Each panel 5, 6 comprises an opening 18, 19 situated at the level of radiation protection glazing 17. Here, radiation protection glazing 17 is situated at the level of the two internal vertical sections 13 and of the two adjacent horizontal sections 12 (more precisely, the U-shaped openings of these four sections 12, 13 are oriented towards the edges of radiation protection glazing 17). The radiation protection screen comprises two glazing beads 20, 21 (in this case made of aluminum) which are arranged at the junction of the radiation protection glazing 17 with the openings 18, 19 of panels 5, 6 and which, when assembled, form a U-shaped section whose central branch is arranged against and each lateral branch encircles a panel 5, 6 at its opening 18, 19. A first glazing bead 20 has a L-shaped cross-section, a first bar 22 of which (the one forming the central branch of the U of the two glazing beads 20, 21 assembled) encircles internal vertical sections 13 and adjacent horizontal sections 12 and a second 23 bar covers the peripheral edge of opening 18 of non-radiation protective rear panel 6. The first bead 20 is fixed, on the one hand, to the two internal vertical sections 13 and to the two adjacent horizontal sections 12, and, on the other hand, to non-radiation protective rear panel 6. The second glazing bead 21 is a simple box that covers the peripheral edge of the opening 19 of radiation protective front panel 5. In order to ensure a continuity of the radiation protection at the level of radiation protection glazing 17, the inner panel of radiation protective front panel 5 comprises all along the edge of its opening 19, a groove 24. In this groove 24 are arranged the glazing of radiation protection 17 and an additional radiation protection sheet 25 (typically leaded sheet). The additional radioprotection sheet 25 covers the portion of radiation protection glazing 17 disposed in groove 24. Second glazing bead 21 completely covers the additional radiation protection sheet 25 and the solid part of the inner panel surrounding groove 24. As a result, second glazing bead 21 can be fixed to radiation protective front panel 5 by screwing without breaking the continuity of radiation protection (the screws pass through second glazing bead 21 and the solid part of the inner panel which surrounds groove 24). Radiation protection screen 1 comprises a peripheral casing 26 (here, aluminum) which forms its edge and its outer limit. Peripheral casing 26 covers the outer peripheral edges of the two panels 5, 6 and is fixed to frame 4. In the present embodiments, for each upper and lateral outer peripheral edge, peripheral casing 26 is a section 27 having the shape of a U with a central panel 28 and two lateral branches 29, each side panel 29 covering the edge outer peripheral of a panel 5, 6, and central branch 28 forming the edge of radiation protection screen 1. For the lower peripheral edge, peripheral casing 26 is formed by a skirting board 30. In the first example, skirting board 30 is adapted to be fixed to a floor so as to make radiation protection screen 1 fixed. In the second example, skirting board 30 is also attached to wheels 31 so as to make the radiation protection screen 1 movable. Here, each wheel 31 is pivotally mounted relative to skirting board 30 along a vertical axis to facilitate the change of orientation of the radiation protection screen 1. From skirting board 30 hangs a base 32 (here, stainless steel) which surrounds wheels 31. This base 32 comprises a horizontal upper wall 33 which is connected to skirting board 30 and framework 4, and four vertical side walls 34 which hang from upper wall 33 and which surround wheels 31. Typically, side walls 34 extend from upper wall 33 to a distance close to the ground (about 1 centimeter from the ground). In the second example, wheels 31 are fixed to the underside of a fixing plate 35 whose upper face is fixed to the lower face of upper wall 33. In the second example, in order to ensure radiation protection at the level of wheels 31, base 32 comprises a radiation protection film (typically a leaded sheet). The radiation protection film of base 32 and the radiation protection sheet of radiation protective panel 5 are arranged in such a way as to ensure a continuity of the radiation protection. Here, the radiation protection sheet film extends along the portion of upper wall 33 which extends on the side of front face 2, and along side wall 34 which is also located on the side of front face 2. The radioprotection film is covered by the front part of upper wall 33 and front side wall 34. Finally, in order to easily direct the movement of radiation protection screen 1, the latter comprises at least one handle 36 (here, two handles 36). In this case, each handle 36 is a hollow handle which is arranged in an orifice 37 made in the central branch of each section 27 associated with a lateral outer circumferential edge of radiation protection screen 1. It is also possible to provide solid handles 38, for example tubular. Handles 38 preferably include an antibacterial material on their surface. For example, the handles comprise a surface metallized with ferrous or non-ferrous metals and cold-solidified. In addition to its properties conferring rigidity without burdening the radiation protection screen, framework 4 also makes it possible to securely fix an object to the non-radiation protective rear panel 6. This fixation is done by resting on at least one section 9, 10, 11, 12, 13 of framework 4. The fixed object can thus be a horizontal shelf. In order to limit the space requirement, the tablet may comprise a first part fixed to framework 4 and a second part articulated to the first part. In the case of a fixed radiation protection screen 1, the fixed object can be a worktop (which can also be supported on other supports). According to a variant, at least one, preferably two support arms 39 may be attached to framework 4 or to rear panel 6. Support arm 39 may serve as a handle 38. Furthermore, in order to avoid tilting of movable radiological protection screen 1 because of the weight of the object which is fixed there and of the material which rests on it, upper wall 33 of base 32 extends more on the side of the rear face 3. Finally, the presence of framework 4 also makes it possible to have a radiation protection screen 1 comprising passages making it possible to pass cables (for example electrical cables) and to have power outlets for electrical equipment (in particular the one resting on the objects fixed to the non-radiation protective rear panel 6. In addition, the screen may include at least one sticker 40 on one or both sides. Sticker 40 can be used to customize the screen, affix a mark or decorate the screen. Preferably, the sticker is antimicrobial. The invention further relates to a system comprising at least two screens connected or capable of being coupled together, at least one of which is as previously described. Preferably, the system comprises a central screen carrying one or more, preferably two, side screens. The extra screens protect more people, especially up to 4 to 5 people with two side screens. According to a variant, the central screen comprises a base and wheels and preferably, the side screens do not include any wheel. According to one variant, the screens are coupled together by means of at least one hinge. Preferably, the hinge comprises a radiation protective element, or a radiation protective panel comprises an extension covering the hinge. Preferably, the screen or the system comprises a mechanism configured to vary the height of the screen or of the system relative to the ground. For example, an elevation of a few millimeters makes it easier to move while a lowering so as to be in contact with the ground makes it possible to improve radiation protection. |
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abstract | An extreme ultraviolet light generation apparatus may include: a chamber in which extreme ultraviolet light is generated from plasma generated by irradiating a target supplied into the chamber with a laser beam; a target generator that supplies the target into the chamber as a droplet; a droplet measurement unit that measures the droplet supplied from the target generator into the chamber; and a shielding member that shields the droplet measurement unit from electromagnetic waves emitted from the plasma, the droplet measurement unit including: a light source that emits continuous light to the droplet; a window provided in the chamber to allow the continuous light to transmit therethrough; and an optical sensor that receives the continuous light via the window. The shielding member includes a shielding body provided on the chamber side with respect to the window and configured to cover an optical path of the continuous light. |
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abstract | A system for controlling the position of an articulated robotic arm in a robotic catheter procedure system, includes an articulated robotic arm, a first controller coupled to the articulated robotic arm and a patient table. The patient table includes a user interface and a second controller coupled to the user interface and the first controller. The second controller is programmed to generate a control signal in response to a user input received using the patient table user interface, the user input indicating a change in position of the patient table. The second controller is also programmed to transmit the control signal to the patient table and to transmit the control signal to the first controller. |
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summary | ||
claims | 1. A charged particle beam apparatus, comprising:a charged particle beam generator having a charged particle source;a charged particle optical system that enters charged particle beams emitted from the charged particle source on a sample;a vacuum evacuating means that evacuates the charged particle beam generator and the charged particle optical system; anda subsidiary vacuum pump that evacuates the charged particle beam generator, andwherein the charged particle source is configured of a field emission type charged particle source and the subsidiary vacuum pump is configured of a first non-evaporable getter pump comprising an alloy surface that extends orthogonally to a direction in which the charged particle beams are emitted from the field emission type charged particle source,wherein, the field emission type charged particle source is disposed to emit the charged particle beams in a gravity direction,wherein an electrode having an aperture through which the charged particle beams passes is provided immediately below the field emission type charged particle source,wherein the first non-evaporable getter pump is disposed around the aperture on the electrode surface, andwherein the electrode has a groove formed on a surface thereof, and the first non-evaporable getter pump is formed on a bottom of the groove. 2. The charged particle beam apparatus according to claim 1, further comprising a heater provided on the rear of the electrode. 3. The charged particle beam apparatus according to claim 1, wherein the electrode has a groove formed on the electrode surface, and the first non-evaporable getter pump is formed in a sheet shape and set on the bottom of the groove. 4. The charged particle beam apparatus according to claim 3, wherein a portion to which the charged particle beams of the first non-evaporable getter pump is irradiated is provided with a shield plate. 5. The charged particle beam apparatus according to claim 1, wherein the charged particle beam generator includes a magnetic shield, a heater provided around an outer wall at an atmospheric side, and a second non-evaporable getter pump that is disposed in a region surrounded by the magnetic shield along an inner wall. 6. The charged particle beam apparatus according to claim 1, wherein the electrode has a cup shape and the cup-shaped electrode includes a cylindrical heater on a side thereof, and a third non-evaporable getter pump disposed along a side of the cylindrical heater, the circumference of the third non-evaporable getter pump being surrounded by a magnetic shield. 7. The charged particle beam apparatus according to claim 6, wherein the side of the magnetic shield is provided with the apertures. 8. The charged particle beam apparatus according to claim 1, wherein the charged particle beam generator includes a region where the field emission type charged particle source is disposed and a vacuum chamber, the charged particle beam generator being connected to the vacuum chamber via the aperture of the electrode and the vacuum chamber being provided with a main vacuum evacuating means and a sub vacuum evacuating means. 9. The charged particle beam apparatus according to claim 8, wherein an ion pump is used as the main vacuum evacuating means and a fourth non-evaporable getter pump is used as the sub vacuum evacuating means. 10. The charged particle beam apparatus according to claim 1, wherein a heating temperature when the first non-evaporable getter pump is activated is set to be higher than a baking temperature that promotes degassing by heating the apparatus when vacuum evacuates. 11. The charged particle beam apparatus according to claim 1, wherein a portion to which the charged particle beams of the first non-evaporable getter pump is irradiated is provided with a shield plate. 12. A charged particle beam apparatus, comprising:a charged particle beam generator having a charged particle source;a charged particle optical system that enters charged particle beams emitted from the charged particle source on a sample;a vacuum evacuating means that evacuates the charged particle beam generator and the charged particle optical system; anda subsidiary vacuum pump that evacuates the inside of charged particle beam generator evacuated by the vacuum evacuating means, whereinthe charged particle source is a field emission type charged particle source,the subsidiary vacuum pump is configured of a first non-evaporable getter pump comprising an alloy surface that extends orthogonally to a direction in which the charged particle beams are emitted from the field emission type charged particle source, andthe charged particle beam generator includes a magnetic shield, a second non-evaporable getter pump that is disposed in a region surrounded by the magnetic shield along an inner wall of the charged particle beam generator, and a heater that heats the second non-evaporable getter pump around an outer wall at an atmospheric side,the field emission type charged particle source is disposed to emit the charged particle beams in a gravity direction,an electrode having an first aperture through which the charged particle beams passes is provided immediately below the field emission type charged particle source,the first non-evaporable getter pump is disposed around the first aperture on the electrode surface, andthe electrode has a groove formed on a surface thereof, and the first non-evaporable getter pump is formed on a bottom of the groove. 13. The charged particle beam apparatus according to claim 12, further comprising:a cup-shaped electrode provided immediately below the field emission type charged particle source, the cup-shaped electrode having a second aperture through which the charged particle beams passes,wherein the cup-shaped electrode includes a cylindrical heater on a side thereof, and a third non-evaporable getter pump disposed along a side of the cylindrical heater, and a magnetic shield surrounding the circumference of the third non-evaporable getter pump along the side of the heater. 14. The charged particle beam apparatus according to claim 13, wherein the side of the magnetic shield is provided with the apertures. 15. The charged particle beam apparatus according to claim 12, wherein the charged particle beam generator includes a vacuum chamber connected to the charged particle beam generator via the first aperture through which the charged particle beams passes, the vacuum chamber being provided with a main vacuum evacuating means and a sub vacuum evacuating means. 16. The charged particle beam apparatus according to claim 15, wherein an ion pump is used as the main vacuum evacuating means, and a fourth non-evaporable getter pump is used as the sub vacuum evacuating means. 17. The charged particle beam apparatus according to claim 12, wherein a heating temperature when the second non-evaporable getter pump is activated is set to be higher than a baking temperature that promotes degassing by heating the apparatus when vacuum starts. |
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description | This application claims the benefit of the prior foreign application: Japanese Patent Application No. 2004-176193 filed on Jun. 14, 2004 in the Japan Patent Office and the entire disclosure of which is incorporated herein by reference in this application. 1. Field of the Invention The present invention relates to a surface illuminator (i.e. a surface light source, a surface lighting device, a planer or plane light source, a flat light source, an edge light source, a side light source) that uses a plate-like or panel-like light guide (i.e. light guiding member, optical waveguide, optical or light conducting member) and at least one point light source (i.e. a point-like or dot-like light source), such as a light emitting diode/diodes (LED/LEDs). The present invention further relates to the surface illuminator typically for use in a backlighting or front-lighting of a liquid crystal display (LCD). 2. Description of the Related Art The liquid crystal displays (LCDs) are being widely used as information displays for mobile or portable electronic information devices such as mobile cellular telephones, digital cameras, video cameras, mobile electronic information terminals such as PDA (private digital assistant), portable or notebook-like personal computers and television receivers. Since the liquid crystal displays are non-emissive or passive opt-electronic information displays, the liquid crystal displays are generally used in combination with the surface light source as backlighting or front-lighting devices that illuminate the liquid crystal displays from back side or front side thereof. The liquid crystal display provided with a surface light source having the LED/LEDs with low power consumption and the light guide member (i.e. light guide plate or panel) is being widely used for such mobile or portable electronic information devices, because these mobile electronic information devices are mainly driven by batteries. A first conventional surface illuminator using a light guide plate and at least one point-like light source is shown as a prior art, for example, in FIG. 5 of U.S. Pat. No.; 6,627,922 B1 (the corresponding Japan Patent publication No.: P2000-315825 A). According to the specification related to FIG. 5 of U.S. Pat. No.; 6,627,922, the conventional light source is such that: “In the case where such light emitting device is installed on the side surface of the light transmitting plate to constitute a backlight, as shown in FIG. 5, the chip-type light emitting device has a structure constituted in such a manner that a side surface emitting chip-type light emitting device 20 is arranged on one side wall of the light transmitting plate 30 in a definite interval, light is allowed to be incident on the inside of the light transmitting plate 30 and is allowed to be scattered within the light transmitting plate 30 to allow light to be applied from the surface the light transmitting plate 30. As a consequence, a bundle of light that is radiated from one side surface is such that a strong light is emitted in a central direction and the directivity thereof is narrowed down. As a consequence, as shown in FIG. 5, when light emitting devices are arranged in a definite interval on a side surface of the light transmitting plate 30, a portion which is referred to as a dark portion 31 is generated in which light is not allowed to be incident at a portion of the light transmitting plate 30 between the light emitting devices 20. A portion of such dark portion 31 is compensated with light which is reflected and brought back within the light transmitting plate 30, but the dark portion 31 has a problem such that the portion has a different luminance from a portion on which light is directly allowed to be incident so that the luminance does not become uniform on the entire surface of the light transmitting plate 30”. A second conventional surface illuminator using a light guide plate and at least one point-like light source is illustrated, in which the second conventional surface light source is indicated as a prior art, for example, in FIG. 10 of U.S. Pat. No.; 6,283,602 B1 (the corresponding Japan Patent publication No.: 10-260405). According to the specification related to FIG. 10 of U.S. Pat. No.; 6,283,602 B1, the conventional light source is such that: “Hitherto, as the foregoing lighting device, the lighting device shown in FIG. 10 is known which has a planar light guide 101 and point-source lights 102 which are positioned to face a light incident surface 101a of the light guide 101. In this conventional device, the light emitted from the point-source lights 102 is diverged by lenses 103, respectively, and the diverged light then radiates in a planar form from a light emitting surface 101b of the light guide 101. In the above known type of lighting device, however, the area in which the light emitted from the point-source lights 102 can be guided is restricted to predetermined angular areas A. A sufficient luminance level of light can be obtained in the areas A, but not in the portions outside the areas A. As a result, the overall light emitting surface 101b cannot emit light with a uniform luminance level. In these conventional surface illuminators, one or more point-like light sources are positioned adjacent to, in contact with or buried into a side surface of the light guide plate. These conventional surface illuminators have such drawback that it is difficult to produce a uniform surface brightness or luminance of the light guide plate along entire areas of that surface lighting surface i.e. light output surface, since the point-like light source, especially LED has a very narrow spread angle or directivity and resultantly the surface lighting surface has not only bright areas but also dark areas, i.e. uneven surface brightness or luminance along or over its lighting surface area. One prior art is U.S. Pat. No.; 6,627,922 B1 (the corresponding Japan Patent publication No.: P2000-315825 A) that discloses a chip-type light emitting diode having a directivity with wide radiation angle in order to improve the drawback of conventional chip-type light emitting diodes having narrow directivity as shown in FIG. 10 of the same U.S. and JAPAN Patent documents. However many number of the improved light emitting diodes (LEDs) are yet required when the LEDs are used in backlighting or front-lighting of the liquid crystal displays with a comparatively large sized viewing screen used as the mobile information terminals. Another prior arts are disclosed to improve the drawback of the first and second conventional surface light sources or surface illuminator, for example, in FIG. 1 to FIG. 6 of U.S. Pat. No.; 6,283,602 (the corresponding Japan Patent publication No.: 10-260405), in FIG. 1 to FIG. 14 of U.S. Pat. No.; 6,193,383 (the corresponding Japan Patent publication No.: 2000-011723 A), U.S. Pat. No.; 6,283,602 (the corresponding Japan Patent publication No.: 10-284803), Japan Patent publication No.: 10-282368 and U.S. Pat. No.; 5,664,862. U.S. Pat. No.; 6,283,602 disclosed such a lighting device that in a lighting device in which planar light is emitted from the planar light emitting surface of a light guide by using a point-source light, such as an LED, the emitted light having a uniform luminance level is obtained on the overall light emitting surface. The lighting device has a point-source light 18 for emitting light in a point-like form. A planar light guide 16 radiates light in a planar form from the planar light emitting surface 16a. A linear light guide 19 is disposed between the point-source light 18 and the planar light guide 16. The point-like light emitted from the point-source light 18 is converted into linear light by the linear light guide 19, and the linear light is guided into the planar light guide 16 through the light incident surface 16b. Since the linear light is incident on the planar light guide 16, the light having a uniform luminance level can be obtained on the overall light emitting surface 16a. U.S. Pat. No.; 6,193,383 discloses such a linear light source unit that an elongated transparent light leading member is provided above a light source, leading member is provided opposite to the light source and a hole is formed in the light leading member at a position above the light source. The hole has an inverted triangular shape, opposite sides of the hole are provided for reflecting light beams emitted from the light source in a longitudinal direction of the light leading member. U.S. Pat. No.; 5,664,862 discloses such an edge light for a panel display that the edge light for projecting light into a lighting panel through an end surface of the lighting panel. The edge light includes a thin transparent optical guide member having an elongate portion and at least one end portion extending from the elongate portion. The elongate portion has a planar surface and a shaped surface generally parallel to the planar surface and configured for reflecting light within the guide member through one of the planar surface and the shaped surface. Either the planar surface or the shaped surface is positioned adjacent the end surface of the lighting panel when the edge light is used to illuminate the panel. The edge light also includes a light source positioned at the end portion for projecting light into the elongate portion of the optical guide member. U.S. Pat. No.; 6,283,602 discloses such linear light guide unit that an elongated transparent light leading member is provided above a light source, leading member is provided opposite to the light source and a hole is formed in the light leading member at a position above the light source. The hole has an inverted triangular shape, opposite sides of the hole are provided for reflecting light beams emitted from the light source in a longitudinal direction of the light leading member. The surfaces light sources or the linear light guides disclosed in these prior arts are such that the surface illuminator includes a linear (i.e. bar-like or rod-like) light guide member having a linear light output side and dual opposed end surfaces, at least one point light source or LED positioned adjacent to the at least one end surface and a substantially rectangular surface lighting light guiding plate having a side surface and a surface lighting major surface, in which the linear light guide member is positioned adjacent to along the side surface of the surface lighting light guiding plate. However, the surface illuminators in these prior arts are not yet sufficient to produce a uniform surface brightness or luminance along or over an entire area of a surface lighting or light emitting surface of the surface lighting light guide member. A main object of the present invention is to improve the surface illuminators i.e. surface light sources described in the related art, in which the present invention proposes the surface illuminator having a more uniform surface brightness or luminance along or over an entire area of the surface lighting or emitting surface of the surface lighting light guide member. In accordance with one embodiment of the present invention, a surface illuminator comprises: a first light guide member for a surface lighting having a first light exiting surface and a first light entering surface; a second light guide member for a light distribution having a second light exiting surface and a second light entering surface; at least one point light source optically communicated with the second light entering surface; a channel light guide member having a fiber optic channel array having a plurality of light guiding portions optically isolated one another; and wherein the channel light guide member is disposed between the first light guide member and the second light guide member. The first light guide member, the channel light guide member channel light guide member and the second light guide member are interposed laterally or vertically respectively in that order. The second light guide member is a light distributing light guide that acts as a light distribution for distributing, spreading or dispensing light entered therein from the point light source. In accordance with another embodiment of the present invention, a surface illuminator comprises: a surface lighting light guide member having a light emitting first major surface, a second major surface opposed to the first major surface and at least one light side surface; an elongated light guide member having a linear or nonlinear elongated member, at least one surface and at least one light receiving portion; at least one point light source optically communicated with the at least one light receiving portion; and a channel light guide member having a plurality of optical core channel elements and a plurality of optical clads alternately aligned to form an elongated fiber optic channel array having a plurality of light entrance core surfaces and a plurality of exit core surfaces opposed to the light entrance core surfaces; and wherein the channel light guide member is interposed between the surface lighting light guide member and the elongate light guide member. In accordance with a still another embodiment of the present invention, a surface illuminator comprises: a surface lighting light guide member having a light emitting first major surface, a second major surface opposed to the first major surface and at least one side surface; an elongated light guide member having a linear or nonlinear elongated member, at least one surface and at least one end surface and/or corner surface that act as at least one light receiving portion; at least one point light source optically communicated with the at least one light receiving portion; a channel light guide member having a plurality of optical core channel elements and a plurality of optical clads alternately aligned to form an elongated fiber optic channel array having a plurality of light entrance core surfaces and a plurality of exit core surfaces opposed to the light entrance core surfaces; wherein light from the at least one point light source enters the elongate light guide member and the light transmits therein toward at least one substantially lengthwise direction thereof; and wherein the channel light guide member is interposed between the surface lighting light guide member and the elongate light guide member. In these embodiments of the invention, the light entrance core surfaces and the light exit core surfaces may be disposed to be in contact with, connected with and/or in close vicinity to the at least one surface of the elongate light guide member and the at least one side surface of the surface lighting light guide member respectively in that order. That is, the light entrance core surfaces may be disposed to be in contact with, connected with and/or in close vicinity to the at least one surface of the elongate light guide member and the light exit core surfaces may be disposed to be in contact with, connected with and/or in close vicinity to the at least one side surface of the surface lighting light guide member. In these embodiments of the invention, light may enter from the light entrance core surfaces into the cores, may exit from the light exit core surface and the light may be received in the at least one light side surface to transmit within the surface lighting light guide member for outputting from the light emitting surface. In these embodiments of the invention, the optical clads may be composed of air having a refractive index lower than the refractive index of the cores made of substantially transparent light guide material. In these embodiments of the invention, the optical clads may be composed of substantially transparent light guide material having a refractive index lower than the refractive index of the cores made of substantially transparent light guide material. In these embodiments of the invention, the optical clads may be composed of substantially light reflecting material. In the some embodiments of the present invention, the surface lighting light guide member, the channel light guide member and the elongate light guide member may be positioned in close vicinity in that order. In the some embodiments of the present invention, the surface lighting light guide member, the channel light guide member and the elongate light guide member may be connected in that order to form an integrated light guide unit. In the some embodiments of the present invention, each of the optical channel elements may have a light entrance surface/portion and a light exit surface/portion opposed to the light entrance surface/portion, and an area of the light entrance surface/portion is similar in size to the area of the light exit surface/portion. In the some embodiments of the present invention, each of the optical channel elements may have a light entrance surface/portion and a light exit surface/portion opposed to the light entrance surface/portion, and an area of the light entrance surface/portion is smaller in size than the area of the light exit surface/portion. In the some embodiments of the present invention, a width of each of the optical channel elements may be substantially unchanged along the elongated optical channel array. In the some embodiments of the present invention, a width of each of the optical channel elements may be variably changed along the elongated optical channel array. In the some embodiments of the present invention, a width of each of the optical channel elements may be variably changed along the elongated optical channel array in such a way that the width increases in accordance with a distance from the point light source. In the some embodiments of the present invention, a pitch between adjacent optical channel elements may be substantially unchanged along the elongated optical channel array. In the some embodiments of the present invention, a pitch between adjacent optical channel elements may be variably changed along the elongated optical channel array. In the some embodiments of the present invention, a pitch between adjacent optical channel elements may be variably changed along the elongated optical channel array in such a way that the pitch decreases in accordance with a distance from the point light source. A light guide unit comprises the surface lighting light guide member (or portion), the channel light guide member (or portion) and the linear or nonlinear light guide member (or portion). In some embodiments of the present invention, the light guide unit may comprise a single integrated first composite unit, wherein the surface lighting light guide member (or portion), the channel light guide member (or portion) and the linear or nonlinear light guide member (or portion) are connected laterally to one another to form the single integrated first composite unit or a unitary composite, as shown in e.g. FIG. 12 and FIG. 23. In stead, in another embodiments of the present invention, the light guide unit may comprise the surface lighting light guide member (or portion) and a second composite unit composed of the channel light guide member (or portion) and the linear or nonlinear light guide member (or portion) as shown in e.g. FIG. 10 and FIG. 21. The channel light guide member (or portion) is laterally connected with the linear or nonlinear light guide member (or portion) to form the second composite unit and the surface lighting light guide portion is laterally in contact with or adjacent to the channel light guide portion of the composite unit. In stead, in still another embodiments of the present invention, the light guide unit may comprise the linear or nonlinear light guide member (or portion) and a composite unit composed of the surface lighting light guide member (or portion) and the channel light guide member (or portion) as shown in e.g. FIG. 11 and FIG. 22. The surface lighting light guide member (or portion) is laterally connected with the channel light guide member (or portion) to form a third composite unit and the channel light guide portion of the third composite unit is laterally in contact with or adjacent to the linear or nonlinear light guide member (or portion). In stead, in other embodiments of the present invention, the light guide unit is composed of separated members of the surface lighting light guide member, the channel light guide member and the linear or nonlinear light guide member as shown in e.g. FIG. 20. The separated members are disposed in such a manner that the channel light guide member is sandwiched laterally between the surface lighting light guide member and the linear or nonlinear light guide member (or portion), in which the surface lighting light guide member is laterally in contact with or adjacent to the channel light guide member and the channel light guide member is laterally in contact with or adjacent to the linear or nonlinear light guide member. A refractive index (n) i.e. an index of refraction in regards to the linear or nonlinear light guide member or portion (n=n1), the channel light guide member or portion having the channel light guide elements (n=n2) and the interposers (n=n4), and the surface lighting light guide member portion (n=n3) may be selected from anyone in the following combination of the index (a), (b), (c), (d), (e) and (f): (a); n1=n2=n3>n4 (e.g. FIG. 12, FIG. 23, FIG. 20), (b); n1=n2<n3 and n1=n2>n4 (e.g. FIG. 10, FIG. 21, FIG. 20), (c); n1<n2=n3 and n2>n4 (e.g. FIG. 11, FIG. 22, FIG. 20), (d); n1<n2<n3 and n2>n4 (e.g. FIG. 20), (e); n1=n2>n3 and n2>n4 (e.g. FIG. 20), and (f); n1<n2=n3>n4 (e.g. FIG. 20). The present invention will now be described in detail with reference to the accompanying drawings, wherein elements or parts depicted in the drawings are not necessarily shown to scale and wherein like or similar elements, parts or portions are denoted by the same reference numeral in the several views. Therefore, a duplicated description for the like or similar elements, parts or portions attached with the same reference numeral may be omitted. Reference is made to FIG. 1 through FIG. 12 showing a first embodiment of the present invention. In the drawings; FIG. 1 is a schematic exploded perspective view showing a surface illuminator of a first embodiment, FIG. 2 is a schematic exploded top view showing the surface illuminator of the first embodiment, FIG. 3 is a schematic cross sectional view showing the surface illuminator of the first embodiment taken along the line A–A′ of FIG. 1, FIG. 4 is a schematic cross sectional view showing the surface illuminator of the first embodiment taken along the line B—B of FIG. 1, FIG. 5 is a schematic top view showing the surface illuminator, FIG. 6 is a schematic bottom view showing the surface illuminator, FIG. 7 is a schematic enlarged perspective view showing the optical channel light guide, and FIG. 8 is a schematic enlarged partial top view showing the surface illuminator showing an example of optical path of light which travels within the light guide unit 100. As shown in FIG. 1 through FIG. 8, a surface illuminator is briefly composed of a light guide unit 100 and at least one light emitting diode (LED) or point light source. The surface illuminator is generally called as a surface lighting device or apparatus, a planer or plane light source, a flat light source, an edge light source or a side light source, in which these technical terms are substantially similar, the same or equivalent meanings. The light guide unit or light guiding unit 100 is composed of at least one light transmitting member having a substantially transparent (i.e. transparent, translucent, opaque or semi-transparent, semi-translucent, semi-opaque, light transmissive, light transmitting or light permeable) material. As the substantially transparent materials for the light guide unit or light guiding unit 100, substantially transparent or light transmissive polymers or resin may be suitably used such as acrylic resin, typically polymethyl-methacrylate (PMMA) with a refractive index of about 1.49–1.50, polycarbonate (PC) with a refractive index of about 1.58–1.59, polystyrene (PS) with a refractive index of about 1.59–1.60, acryl-polystyrene copolymer with a refractive index of about 1.51–1.57, polyethylene terephthalate (PET) with a refractive index of about 1.66, epoxy with a refractive index of about 1.55–1.61, polyimide fluoride with a refractive index of about 1.46–1.47, polyvinylidene chloride with a refractive index of about 1.47, silicone resin with a refractive index of about 1.41, silicone rubber with a refractive index of about 1.42, polytetrafluoroethylene (PTFE) with a refractive index of about 1.35, etc. As such materials, transparent polymer or resin with a controllable refractive index may also be used such as the UV curable epoxy based resin including fluorine and sulfur contents with the controllable refractive index range between 1.42 and 1.70 that is commercially available from such as NTT Advanced Technology Corporation (NTT AT), JAPAN. The light guide unit 100 is composed of a surface lighting light guide member (surface lighting light guide) 30 having a substantially transparent planer plate-like member, a linear light guide member (linearly elongated light guide) 10 having a substantially transparent plate-like, bar-like or rod-like linear member and an optical channel light guide member (channel light guide) 20 disposed therebetween, in which the optical channel light guide member 20 is sandwiched laterally by the linear light guide member 10 and the surface lighting light guide member 30. The surface lighting light guide plate 30 may be further composed of typically or generally a substantially transparent rectangular member having a first major surface i.e. a front surface 30a to act as a surface lighting surface i.e. light emitting surface, a second major surface i.e. a rear surface 30b opposed to the first major surface 30a, a first side surface (i.e. side, edge, end) 30c, a second side surface 30d opposed to the first side surface 30c, a third side surface 30e, a fourth side surface 30f opposed to the third side surface 30e. The surface lighting surface 30a may have a substantially rectangular and a substantially planer surface. The surface lighting light guide member 30 may have a substantially uniform or equal thickness between the opposed major surfaces 30a and 30b as shown in FIG. 1, FIG. 3 and FIG. 4. The second major surface 30b may have at least one light diffusing means 50 disposed thereon/therein for diffusing or scattering the light reached or struck to the light diffusing means 50 to redirect the light toward the first major surface 30a so that the light emits from the first major surface 30a to an exterior thereof for illuminating a liquid crystal display (LCD) 220 in FIG. 9. The light diffusing means 50 may be composed of at least one light diffusing or scattering film or at least one rough surface area, at least one grooved surface area and/or at least one prism surface area and may be disposed partially or entirely on the second major surface 30b, while the surface areas without the light diffusing means 50 may be planer, smooth or flat. The light diffusing means 50 is preferably provided with a predetermined diffusing pattern on the second major surface 30b to produce a substantially uniform, even or equal surface brightness or luminance along or over the surface lighting surface 30a. As shown in FIG. 6 (and FIG. 3, FIG. 4), a plurality of the light diffusing means 50 may form a linear gradation pattern having a plurality of stripes, belts or lines with a substantially uniform width aligned in parallel to one another with a variable distance. The linear gradation pattern may be made in such a manner that a quantity of the stripes, belts or lines gradually increase in a stepwise or continuous fashion from the first side surface 30c to act as a light entrance or incident portion toward the opposed second side surface 30d, while a pitch or spacing between the adjacent stripes, belts or lines gradually decrease in a stepwise or continuous fashion from the light entrance side surface 30c toward the opposed side surface 30d. Since the light diffusing means 50 have such a gradation pattern for diffusing light, diffusing areas in the surface lighting light guide 30 can be increased in proportion to a distance from the light entrance side surface 30c toward the opposed side surface 30d, thereby a uniform surface luminance can be produced from the surface lighting surface 30a of the surface lighting light guide 30. The first side surface 30c to act as a light entrance, receiving or incident portion receives light exit or output from the channel light guide 20 in order to introduce the light into the surface lighting light guide member 30. The channel light guide or optical channel light guide member 20 is composed of a plurality of optical channel elements 21 to act as optical cores in the fiber optics (i.e. optical channels, channel light guide elements) with air gaps (air spacing, openings, through holes or interposers) 22 to act as optical clads or claddings in the fiber optics. The optical channel elements 21 and the air gaps 22 are disposed alternately to align substantially in parallel to form a linear optical channel array or a fiber optic channel array. The optical channel elements 21 are separated so as to be isolated optically to one another by the air gaps 22 that are present adjacently between the optical channel elements 21. The channel light guide member 20 is disposed laterally so as to be sandwiched between the surface lighting light guide member 30 and the linear light guide member 10, in such a manner that a light exit surface or face i.e. light output surface or face 20d of the channel light guide member 20 is connected with, in contact with or adjacent to the light receiving side surface i.e. light incident side surface 30c of the surface lighting light guide member 30 and a light entrance surface or face i.e. light input surface or face 20c of the channel light guide member 20 is connected with, in contact with or adjacent to the light exit front side surface 10d of the linear light guide member 10. As shown in FIG. 7, the channel light guide member 20 may be composed of a plurality of optical channel elements or optical cores 21 (21-1, 21-2, . . . and 21n, and 21-1′, 21-2′, . . . and 21-n′) and a plurality of optical clads (or interposers, air spacing, openings, through holes, air gaps) 22 (22-c, and 22-1, 22-2, . . . and 22n, and 22-1′, 22-2′, . . . 22-n′ and 22-c) that exist to position between the adjacent optical channel elements 21, in which the optical channel elements 21 are isolated by the adjacent openings 22. Each of the optical channel elements 21 has parallel opposed walls. Width “w1” of the optical channel elements 21 is substantially equal, while width “w2” of the air clads is variable. The optical core channel elements 21 and the clads 22 are aligned alternately substantially in parallel to form a linear array or a fiber optic channel array of the optical channel light guide 20 as a whole. In this embodiment, the optical core channel elements (or optical channel portions) 21 are variably distributed in quantity along the linear length of the channel light guide member 20 in proportion to the distance from a center “c” of the channel light guide plate 20 toward the opposed ends 20e and 20f, in which the center “c” of the channel light guide 20 i.e. a center air gap 22-c faces the point_like light source 200 positioned at a vicinity of the rear side surface 10c of the linear light guide member 10. A pitch “p” between the adjacent optical channel elements 21 and a width “w” of the slits or air gaps 22 variably or gradually decrease to form a predetermined gradation pattern in a continuous or stepwise manner from the center “c” of the channel light guide 20 toward the end 20e and 20f thereof. Thereby a substantially uniform light output from the light output side or face 20d of the channel light guide member 20 can be produced along the linear length thereof. Since the optical core channel elements 21 with a high refractive index n1 (n1>1) are interposed between the air cores or interposers 22 with the refractive index n2 (n2=1) lower than that of the optical core channel elements 21 along the lengthwise direction of the linear fiber optic array of the channel light guide 20, a plurality of independent small optical waveguides or solid light pipes 21 (21-1, 21-2, . . . and 21n, and 21-1′, 21-2′ . . . and 21-n′) that are optically isolated to one another are formed in the channel light guide member or the fiber optic array 20. The optical core channel elements 21 have a substantially rectangular shape in this embodiment as shown in FIG. 7, in which the light input (entrance) surface (i.e. proximate end face) 21c is substantially equal to the light output (exit) surface (i.e. distal end face) 21d in that area size in each of the optical channel element 21 and each of the optical channel elements 21 has parallel opposed walls. However, each of the optical channel elements 21 may have other shapes, in stead, such as a substantially trapezoidal shape having the opposed light input and output surfaces 21c and 21d and opposed inclined walls. When each of the optical channel elements forms the substantially trapezoidal shape having the area size of the light exit or output surface (distal end face) 21d larger than the area size of the light entrance or input surface (proximate end face) 21c, light beams output from the light exit surface 21d can expand more than the light beams received at the light entrance surface 21c so that the light beams output from the light exit surface 21d have wider directive angle wider than the directive angle of the light beams of the optical core channel elements 21 in FIG. 7. Back to FIG. 1 through FIG. 6, the linear light guide member 10 may be composed of opposed major surfaces 10a and 10b, opposed front and rear side surface (or sides or side face) 10c and 10d, opposed end surfaces 10e and 10f, at least one light receiving portion 10g in the rear side surface 10c and a light reflecting means or reflector 40. The light reflecting means or reflector 40 in this embodiment has a substantially triangular opening or through hole positioned in a substantially center portion of the linear length of the linear guide member 10, in which the light reflecting means 40 i.e. the substantially triangular opening is composed of opposed reflecting surfaces 40a and 40b with a letter “V” shaped configuration, another surface 40c to connect the opposed reflecting surfaces 41 and 42 and a crossed point 40d of the opposed surfaces 41 and 42. The opposed reflecting surfaces 40a and 40b may have opposed inclined or slanted surfaces of which opposed angle may be the same, preferably 30 to 60 degree. The linear light guide member 10 may be disposed to be connected with, in contact with, or adjacent to a first side face 20c of the channel light guide member or plate 20 so that light output from the linear light guide member 10 can pass through mainly the optical channel elements 21. At least one light emitting diode 200 (LED) may be disposed relative to, or in optical communication with the linear light guide member 10 so as to position at the light receiving portion 10g thereof so that a light emitting surface 200a of the LED 200 faces the light reflecting means 40 or the opposed reflecting surfaces 40a and 40b and an optical axis of the LED coincides the cross point 40d of the reflecting surfaces 40a and 40b. Any types of the light emitting diodes (LEDs) may be used for the present invention as point-like light sources such as bare LED chips, encapsulated or packaged LED chips, surface mountable LEDs (SMD type LEDs) and conventional semi-circular or semi-round type LEDs. An encapsulated or packaged LED device having three different kinds of bare LED chips or LED dies may suitably be used for emitting a mixing color of white in conjunction with the light guide unit of the present invention for lighting the liquid crystal displays to display full color images, in which the bare LED chips for emitting different color light i.e. blue, green and red are enclosed in one capsule or package to emit white light from a light emitting window that is made by mixing the different colors therein. Other white color LED devices may be used for the present invention, in which the white color LED devices are composed of a short wavelength (i.e. UV, purple or blue) emitting LED chip and a phosphor material, in which the phosphor material converts light with UV rays, purple or blue color to light with white color. These white color LEDs are commercially available from manufacturers such as Lumileds Lighting U.S. LLS, NICHIA Corporation, Japan, TOYODA GOSEI Co., Ltd, Japan, Stanley Electric Co., Ltd. Japan, Citizen Electronics Co., Ltd. Japan and SEIWA Electric MFG. Co., Ltd. Japan. Referring to FIG. 8 showing a typical optical path within the light guide unit 100, the at least one light emitting diode (LED) 200 may be positioned in contact with, adjacent to or within the light receiving portion 10g of the linear light guide member 10, in which a light emitting window i.e. a light emitting surface 200a of the LED 200 faces the opposed light reflecting surfaces 40a and 40b of the light reflecting means or reflector 40 having a substantially triangular opening within the linear light guide member 10, in which the opposed light reflecting surfaces 40a and 40b have a symmetrical inclined i.e. slant angle with respect to the a vertical line of the another surface 40c. The surfaces 40a and 40b may constitute an interface between the linear light guide member 10 having a first refractive index (n1>1) and air of the opening 40 having a second refractive index (n2=1) lower than the first refractive index. Light “L” indicated by dotted lines with arrows in FIG. 8 (i.e. light rays or light beams) emitting from the LED 200 enters the linear light guide member 10 and the light advances toward the reflector 40. Large volume of light “L1” among the light “L” from the LED 200 reaches the opposed inclined reflecting surfaces 40a and 40b, the light “L1” incident with more than critical angle is reflected by at the opposed inclined reflecting surfaces 40a and 40b based on the total internal reflection (TIR) toward substantially lateral first and second directions opposed to each other and the light “L1” advances to reflect repeatedly based on the TIR toward the substantially opposed ends 10e and 10f along the length of the linear light guide member 10 therein, The rest volume of light “L2” passes the reflector 40 to transmit into the surface lighting light guide member 30 through the substantially triangular opening 40 and the center air clad 22-c, since the light “L2” reached the reflector 40 with less than a critical angle of TIR passes the reflector 40 without reflecting at the inclined reflecting surfaces 40a and 40b. The reflecting sheet or plate 52 may be disposed adjacent to the light diffusing means 53 except for the light receiving portion 10b of LED 200 so as to redirect the light leaked from the linear light guide 10 to return thereto. The optical channel element 21 (i.e. channel light guide elements, optical core channel elements, optical cores) are separated or optically isolated by the interposers 22 (i.e. air clads in this embodiment, optical clads) existing between each of the optical channel element 21, in which a refractive index of the air clads 22 is lower than the refractive index of the optical channel element 21 that are surrounded by air of the slits 22, so that each of the optical channel element 21 constitutes an independent optical waveguide, i.e. optical pipe or light pipe. When the light “L1” reaches the rear side surface 10c of the linear light guide 10, the light “L1” reflects at the rear side surface 10c toward the optical channel light guide 20, the light “L1” further travels to reach the optical channel light guide elements 21 or the air interposers 22. When the light “L1” with more than the critical angle of the TIR reaches the air interposers 22 after reflecting at the rear side surface 10c or after reflecting at the reflector 40, the light is reflected by the air interposers 22 to advance toward substantially lateral direction/directions (i.e. the rear side surface 10c or the end surfaces 10e and/or 10f). When the light “L1” with less than the critical angle of the TIR reaches the air interposers 22 after reflecting at the rear side surface 10c or after reflecting at the reflector 40, the light passes through the air interposers 22 to enter the light incident side surface 30c of the surface lighting light guide 30. The light “L1” reached the light diffusing means 55 diffuses or scatters to become diffused light “L3” and the diffused light “L3” travels toward the optical channel light guide member 20 (the optical core channel elements 21 and the air clad or interposers 22). The diffused light “L3” reached the optical channel light guide elements 21 advances therein to reflect at least one time based on the TIR and the diffused light “L3” passes therethrough to enter the surface lighting light guide member 30 via the light incident or input side surface 30c thereof. The diffused light “L3” with more than the critical angle of the TIR reached the air interposers 21 reflects based on the TIR to advance toward the substantially lateral direction within the linear light guide 10, while the diffused light “L3” with less than the critical angle reached the air clads i.e. air interposers 21 passes therethrough to enter the surface lighting light guide member 30 via the light incident or input side surface 30c thereof. The light “L1” reached the end surface/surfaces 10e and/or 10f reflects at planer, flat or smooth surface portions thereof or diffused at the light diffusing means 55 to become diffused light “L3”, in which the reflected light “L1” further travels to a substantially lateral opposite direction within the linear light guide member 10 and the diffused light “L3” travels to plural directions within the linear light guide member 10. The light “L1” and/or “L3” leaked from the rear side surfaces 10c or from the end surfaces 10e and/or 10f are reflected by the reflecting or diffusing sheet or plate 52 to return the linear light guide member 10. It should be noted that a first volume of the light L1 entered the optical core channel elements 21 is larger than a second volume of the light L1 entered the air clads 22, since all the light L1 reached the optical core channel elements 21 can enter therein, while only the light L1 with less than the critical angle of the TIR reached the air interposers 22 can pass therethrough and the light L1 with more than the critical angle of the TIR reached the air interposers 22 reflects within the linear light guide 10 without passing the air interposers 22. A large volume of first light with strong brightness exits from the optical core channel elements 21 in which the output light has a wide spread angle similar to optical fibers exits therefrom, while a small volume of second light with week brightness exits from the air clads 22. The channel light guide member (i.e. the linear fiber optic array) 20 exits the first bright light and the second week light adjacent to one another along the linear length of the linear fiber optic array 20 and the first bright light and the second week light enter the surface lighting light guide member 30 from the light receiving side surface 30c thereof. The first bright light and the second week light are mixed together at a vicinity of the light receiving side surface 30c within the surface lighting light guide member 30, thereby a substantially uniform or equalized linear light can transmit within the surface lighting light guide member 30. The substantially uniform linear light within the surface lighting light guide member 30 transmits to reflect repeatedly between the opposed major surfaces 30a and 30b based on the TIR from the light receiving side surface 30c toward the opposed side surface 30d and the light gradually emits from the light emitting major surface 30a on the way of transmission. Therefore, the planer output light with a substantially uniform or equalized brightness or luminance can be produced substantially over of the surface lighting major surface 30a of the surface lighting light guide member 30. As described in the above, in this embodiment, since the optical channel light guide elements (optical core channel elements) 21 and/or the interposers (air optical clads) 22 are variably distributed to form the linear fiber optic array as a whole having the gradation pattern, in which the pitch “p” of the optical channel light guide elements 21 and/or the width “w” of the interposers 22 are variably aligned, the channel light guide member 20 can exit a substantially uniform light output along the linear length of the linear fiber optic array and resultantly a uniform surface lighting from the surface lighting light guide member or plate 30 over the light exit major surface 30a thereof can be produced. Referring to FIG. 9, a typical example of the application of the surface illuminator of the present invention, in which FIG. 9 is a schematic enlarged partial cross sectional view showing the first embodiment taken along the line A–C of FIG. 1. As shown in FIG. 9, the surface illuminator composed of the light guide unit 100 and the LED 200 is typically utilized for a surface lighting such as a backlighting of a liquid crystal display device (LCD) 200, so that a viewer or user can see a displayed image of the LCD 220 illuminated by light from the surface lighting guide member 30 positioned in a backside of the LCD 200. As described in above in detail, the light guide unit 100 is briefly composed of the linear light guide member 10 having the opposed major surface 10a and 10b, the light receiving side face 10c, the light exit side face 10d and the reflector 40, the optical channel light guide member 20 having the light receiving side face 20c and the light exit side face 20d, and the surface lighting light guide member 30 having the surface lighting front surface 30a, the opposed rear surface 30b and the light diffusing means 50 disposed in/on the rear surface 30b. The liquid crystal display (LCD) 220 is briefly composed of a liquid crystal panel 221 having opposed transparent plates with opposed transparent electrode films disposed their inner surfaces and liquid crystal material filled between the opposed transparent plates, and opposed polarized films 222 and 223 disposed so as to sandwich the liquid crystal panel 221. A light spreading or prism sheet 51 may be disposed on or adjacent to the surface lighting surface 30a of the surface lighting light guide 30 and a light reflecting sheet or plate 54 may be disposed on or adjacent to the rear surface 30b of the surface lighting light guide 30. The light reflective or shielding sheet 53 may be disposed on or adjacent to cover an end portion of the front surface 30a of the surface lighting light guide 30, a front surface of the linear members 20 and the front surface of the channel light guide member 20, in which only the air clad i.e. air interposer 22 is shown in FIG. 9 and the optical core channel element 21 is not shown in FIG. 9), The light reflective or shielding sheet 53 returns the light leaked undesirably from the front surfaces of the light guide unit 100 thereto and shields light from entering from outside into the light guide unit 100. In stead, the surface illuminator can be utilized for a front lighting (not shown in FIG. 9) of the liquid crystal display device 220 in such a manner that the light reflecting sheet 54 is removed so that the viewer can see indirectly the liquid crystal display 220 through the surface lighting light guide member 30. Reference is made to FIG. 10, FIG. 11 and FIG. 12 illustrating top views of the light guide unit 100 showing three kinds of the light guide unit 100 of the first embodiment. As shown in FIG. 10, a first kind of the light guide unit 100A is composed of the surface lighting light guide member 30 and a composite light guide member (10, 20) of the linear light guide member 10 having the reflector 40 disposed therein and the channel light guide member 20, in which the linear light guide member 10 and the channel light guide member 20 are integrated to form a single unit, and the surface lighting light guide member 30 are preferably positioned laterally in contact with the composite light guide member (10, 20). Light entered the optical core channels 21 of the channel light guide portion 20 in the composite light guide member (10, 20) from the linear light guide portion 10 of the composite light guide member (10, 20) may travel within the optical core channels to reflect totally one or more times therein toward light exit end surfaces 21d thereof and the light may exit effectively from the light exit end surfaces 21d to enter the light receiving side surface 30c of the surface lighting light guide 30 to transmit therein. The composite light guide member (10, 20) and the surface lighting light guide member The composite light guide member (10, 20) and the surface lighting light guide member 30 may be preferably composed of a substantially transparent polymer material, in which a refractive index of the composite light guide member (10, 20) must be substantially the same or lower than the refractive index of the surface lighting light guide member 30. For example, the substantially transparent polymer material used as the composite light guide member (10, 20) may be polymethyl-methacrylate (PMMA) with a refractive index of about 1.49–1.50 and the substantially transparent polymer material used as the surface lighting light guide member 30 may be polymethyl-methacrylate (PMMA) with a refractive index of about 1.49–1.5 or polycarbonate (PC) with a refractive index of about 1.58–1.59. Therefore, light output from an optical channel light guide portion of the composite light guide member (10, 20) toward the surface lighting light guide 30 is prevented from returning back to the composite light guide member (10, 20) by reflecting at the interface between the optical channel light guide portion and the light input side surface of the surface lighting light guide 30. As shown in FIG. 11, a second kind of the light guide unit 100B is composed of the linear light guide member 10 having the reflector 40 and a composite light guide member (20, 30), in which he surface lighting light guide member 30 and the channel light guide member 20 are integrated to form a single unit, and the composite light guide member (20, 30) are preferably positioned in substantially contact with the linear light guide member 10. The composite light guide member (20, 30) and the linear light guide member 10 may be preferably composed of a substantially transparent polymer material, in which a refractive index of the composite light guide member (20, 30) is preferably substantially the same or higher than the refractive index of the linear light guide member 10. For example, the composite light guide member (20, 30) may be made of “PMMA” or “PC” and the linear light guide member 10 may be made of “PMMA”. As shown in FIG. 12, a third kind of the light guide unit 100C is composed of a unitary composite light guide unit (10, 20, 30), in which the surface lighting light guide member 30, the channel light guide member 20 and the linear light guide member 10 having the reflector 40 are connected or unified in that order to form a single integrated unit. The light guide unit 100C i.e. the composite light guide unit (10, 20, 30) may be preferably composed of a substantially transparent polymer material and there is no attention with respect to a combination of the refractive index because of a completely integrated single unit with a single refractive index that differs from the light guide unit 100A and 10B. Therefore, the light guide unit 100C composed of a single polymer material may be manufactured by an injection molding process at the same time. The composite light guide member or unit (10, 20) of the light guide unit 100A in FIG. 10, the composite light guide member or unit (20, 30) of the light guide unit 100B in FIG. 11 and the composite light guide member or unit (10, 20, 30) of the light guide unit 100C in FIG. 12, may be manufactured by various processes using a substantially transparent polymer, for example, laser cutting process, injection molding process, casting molding (or polymerization) process or compression molding process. The laser cutting process may be made by using a laser cutting or engraving machine, in which a light guide plate is processed by scanning of laser beam energy so as to cut in accordance with a predetermined pattern relative to at least the channel light guide 20 and the reflector 40. The injection molding process may be made by using a molding die with a molding pattern including a channel pattern relative to at least the channel light guide 20 and a reflector pattern relative to the reflector 40, in which melted or softened polymer is injected into the molding die and the solid polymer light guide (10, 20) in FIG. 10 and (20, 30) in FIG. 11 or (10, 20, 30) in FIG. 12 is taken out from the molding die after cooling. The casting molding or polymerization process may be made by using a casting die with a pattern including a channel pattern relative to at least the channel light guide portion 20 and a reflector pattern relative to the reflector portion 40, in which liquid resin or monomer including a thermo-sensitive or light-sensitive hardener (i.e. photo-initiator) is poured into the casting die and the solid polymer light guide (10, 20) in FIG. 10 and (20, 30) in FIG. 11 or (10, 20, 30) in FIG. 12 is taken out from the casting die after hardening or polymerizing by application of heat or light. The compression molding process may be made by using a molding die with a molding pattern including a channel pattern relative to at least the channel light guide 10 and a reflector pattern relative to the reflector 40, in which melted or softened polymer are placed in the molding die and compressed by pressing the molding die and the solid polymer light guide (10, 20) in FIG. 10 and (20, 30) in FIG. 11 or (10, 20, 30) in FIG. 12 is taken out from the molding die after cooling. When the above-mentioned process is applied for making the light guide unit 100A, 100B or 100C, a mass production thereof is easily carried out and the light guide unit 100A, 100B or 100C can be supplied in a short delivery time and in comparatively low cost. Reference is made to FIG. 13, FIG. 14 and FIG. 15 showing three modifications of the defusing pattern of the light diffusing means 50 of the surface lighting light guide 30 in FIG. 6, in which FIG. 13, FIG. 14 and FIG. 15 is schematic bottom views of the surface illuminator of the first embodiment of the present invention. As shown in FIG. 13 (and FIG. 3, FIG. 4), a plurality of the light diffusing means 50a disposed in/on the second major surface 30b may be composed of a plurality of dots or dot-like areas 50a to form a gradation pattern and each of the dots or dot-like areas has a substantially uniform area with an arbitrary shape such as a circle in FIG. 13, ellipse, rectangle or polygon. A quantity of the dots or dot-like areas 50a increases in accordance with the distance from the light entrance side surface 30c toward the opposed side surface 30d so that a distributing density of the dots or dot-like areas 50a increases in a stepwise or continuous fashion. Thereby a substantially uniform surface brightness can be produced over substantially entire areas of the surface lighting surface 30a of the surface lighting light guide 30. As shown in FIG. 14 and FIG. 15 (and FIG. 3, FIG. 4), a plurality of the light diffusing means 50b and 50c disposed in/on the second major surface 30b may be composed of a plurality of island-like areas or isolated areas to form a gradation pattern. Each of the island-like areas 50b and 50c may have a different sized area with an arbitrary shape such as the light diffusing means 50b with a rectangular pattern in FIG. 14, the light diffusing means 50c with a circular pattern in FIG. 15. The island-like areas 50b and 50c increase in each size in a stepwise or continuous fashion from the light receiving side surface 30c toward the opposed side surface 30d. Thereby a substantially uniform surface brightness can be produced over substantially entire areas of the surface lighting surface 30a of the surface lighting light guide 30. Reference is made to FIG. 16 through FIG. 19 showing a second embodiment of the present invention. FIG. 16 is a schematic exploded perspective view showing a surface illuminator, FIG. 17 is a schematic exploded top view showing the surface illuminator and FIG. 18 is a schematic top view showing the surface illuminator and FIG. 19 is a schematic perspective view showing a channel light guide 23 used for the surface illuminator. The second embodiment (FIG. 16 through FIG. 19) differs from the first embodiment (e.g. FIG. 1 through FIG. 15) described hereinbefore in the constitution of a channel guide member 23 and a linear light guide member 12 and like or similar elements, parts or portions are denoted by the same reference numeral in these Figures. Therefore, a duplicated description for the like or similar elements, parts or portions attached with the same reference numeral may be omitted hereinafter. A surface illuminator is composed of the light guide unit 110 and a light emitting diode (LED) 200 as a point-like light source. The light guide unit 110 is composed of a plate-like surface lighting light guide member 30, a channel light guide member 23 and a plate-like linear light guide member 12, in which these light guide members 30, 23 and 12 are made of substantially transparent, light transmitting, light guiding or light conducting material. The surface lighting light guide member 30, the channel light guide member 23 and the linear light guide member 12 are disposed laterally in that order so that the channel light guide member 23 is sandwiched between the surface lighting light guide member 30 and the linear light guide member 12. The linear guide member 12 may be composed of a substantially linearly elongated transparent plate having opposed major surfaces 12a and 12b, opposed side surfaces 12c and 12d, opposed ends or end surfaces 12e and 12f, a light receiving portion 12g disposed in/on the rear side surface 12c, a substantially triangular light reflecting means 42 disposed in an interior of the linear guide member 12 and a substantially transparent material 43 disposed in a substantially triangular space of the light reflecting means 42. The light reflecting means or reflector 42 in this embodiment may be composed of opposed reflecting inclined surfaces 42a and 42b with a substantially “V′ shape and another surface 42c to connect the opposed reflecting surfaces 42a and 42b and the substantially transparent triangular polymer member 43 filled in the substantially triangular opening (denoted as the reference numeral 40 in e.g. FIG. 1), in which the reflector 42 may be positioned near a central portion of the linear light guide 12. A refractive index of the substantially transparent triangular polymer member 43 must be lower than the refractive index of the linear light guide member 12, thereby the opposed reflecting inclined surfaces 42a and 42b can reflect light within the linear light guide 12 without entering the polymer member 43, when light with more than critical angle of the TIR reach the opposed reflecting inclined surfaces 42a and 42b. The point_like light source (or LED) 200 is disposed in a light receiving area 12g, i.e. that is a portion near a center “c” of the rear side surface 12c of the linear light guide member 12, in such a manner that a light emitting window or surface of the LED 200 faces the opposed light reflecting surfaces 42a and 42c of the reflector 42. The channel light guide member 23 is composed of a plurality of optical channel elements 21 to act as optical solid cores and a plurality of substantially transparent solid interposers to act as optical solid clads 25. The solid interposers or optical solid clads 25 are disposed between the adjacent optical channels elements or optical solid cores 21 in such a manner that the optical solid cores 21 and the optical solid clads 25 are alternately aligned in substantially parallel to form a linear fiber optic channel array 23. Therefore, the optical solid cores 21 are separated to isolate optically to one another by the optical solid clads 25 in the lengthwise direction of the channel light guide member 23 i.e. the linear fiber optic channel array 23. As shown in FIG. 19, in this embodiment, the optical channel elements (or optical channel portions) 21 have substantially the same width “w1” and the optical channel elements 21 are variably distributed to increase in quantity or distribution density along the linear length of the channel light guide member 23 in proportion to the distance from a center “c” of the channel light guide member 23 toward the opposed ends 23e and 23f. A pitch “p” between the adjacent optical core channel elements 21 and a width “w2” of the solid clad interposers 25 are variably or gradually decreased in a continuous or stepwise manner to form a gradation pattern from the center “c” of the channel light guide member 23 or a center solid clad interposer 25-c toward the end 23e and 23f of the channel light guide member 23, thereby a substantially uniform linear light output from the light output side surface 23d of the channel light guide member 23 can be produced along the linear length thereof. A refractive index or an index of refraction of the interposers (i.e. solid clads) 25 must be lower than the refractive index of the optical channel elements (i.e. optical cores) 21. The solid interposers i.e. solid clads 25 with a comparatively low refractive index may be composed of substantially transparent polymer material selected from, for example, polyimide fluoride with a refractive index of about 1.46–1.47, silicone resin with a refractive index of about 1.41, polyvinylidene chloride with a refractive index of about 1.47 and epoxy based resin including fluorine and sulfur contents with the refractive index range that is controlled from 1.42 to 1.48. While the optical channel elements (i.e. solid cores) 21 with a comparatively high refractive index may be composed of substantially transparent polymer material selected from, for example, polymethyl-methacrylate (PMMA) with a refractive index of about 1.49–1.50, polycarbonate (PC) with a refractive index of about 1.58–1.59, polystyrene (PS) with a refractive index of about 1.59–1.60, epoxy with a refractive index of about 1.55–1.61 and epoxy based resin including fluorine and sulfur contents with the refractive index range that is controlled from 1.49 to 1.70. Since each of the optical channel elements (optical cores) 21 with a refractive index “n2” is surrounded or interposed laterally by the interposers (solid clads) 25 with the refractive index “n4” lower than “n2” except for the opposed light input surfaces (i.e. proximate end surfaces or light entrance surfaces) 21c and light output surfaces (i.e. distal end surfaces or light exit surfaces) 21d along a lengthwise direction, the independent optical waveguides or light pipes 21 between the opposed light input and output surfaces 21c and 21d are produced separately to one another within the channel light guide plate 23. The optical channel elements 21 and the interposers 23 have a substantially rectangular shape as shown in FIG. 16, in which the opposed light input and output surface 21c and 21d have substantially the same area size. However, each of the optical channel elements 21 and the interposers 15 may have other shapes such as a substantially trapezoidal shape. Further, each area of the light output surfaces 21d of the optical channel elements 21 may be larger than each area of the light input surface 21c of the optical channel elements 21, while the interposers 25 is reversed to the optical channel elements 21, so that light entered the light input surface 21c exits from the light output surface 21d so as to expand the light with wider directivity. The solid interposers 25 may contain a plurality of light diffusing particles to disperse therein and the light diffusing particles may be selected from substantially transparent glass or polymer beads with a refractive index different from the refractive index of the solid interposers 26 or light reflecting or diffusing pigments so that light with wider spread angle can exit from the solid interposers 25 when the light enters an interior of the solid interposers therefrom. Reference is made to FIG. 20 through FIG. 23 illustrating top views of the light guide units 110 showing four kinds of the light guide units 110A, 110B, 100C and 110D of the second embodiment of the present invention. As shown in FIG. 20, a first kind of the light guide unit 110A is composed of the surface lighting light guide member 30, the channel light guide member 23 having the channel light guide elements 21 and the interposers 25, and the linear light guide member 12 having the reflector 42 and the substantially transparent polymer member 43 filled therein, in which all the light guide members 30, 23 and 12 are separated to one another. The light guide members 30, 23 and 12 may be positioned laterally in a side-by-side relationship in that order so as to be or to come in substantially contact with to one another so that the channel light guide member 23 is sandwiched laterally between the light receiving side face 30c of the surface lighting light guide member 30 and the light output surface 12d of the linear light guide member 12. As shown in FIG. 21, a second kind of the light guide unit 110B is composed of the surface lighting light guide member 30 and a composite light guide member (12, 23) of the channel light guide member 23 having the channel light guide elements 21 and the interposers 25, and the linear light guide member 12 having the reflector 42 and the substantially transparent filler member filled therein, in which the composite light guide member (12, 23) and the surface lighting light guide member 30 are separated to one another. The composite light guide member (12, 23) may be positioned in substantially contact with the surface lighting light guide members 30, so that the light output surface 23d of the composite light guide member (12, 23) faces the light receiving surface 30c of the surface lighting light guide member 30. As shown in FIG. 22, a third kind of the light guide unit 110C is composed of the linear light guide member 12a having the reflector 42 and the substantially transparent filler member 43 filled therein, and a composite light guide member (23, 30) of the surface lighting light guide member 30 and the channel light guide member 23 having the channel light guide elements 21 and the interposers 25, in which the surface lighting light guide member 30 and the channel light guide member 23 are integrated to form a single unit. The composite light guide member (23, 30) may be positioned in substantially contact with the linear light guide member 12 so that the light exit surface 12d of the linear light guide member 12 contacts with the light receiving side surface 23c of the channel light guide portion 23 of the composite light guide member (23, 30). As shown in FIG. 23, a fourth kind of the light guide unit 110D is composed of a unitary composite light guide member (12, 23, 30) is composed of the surface lighting light guide member 30, the channel light guide member 23 having the channel light guide elements 21 and the interposers 25 and the linear light guide member 12 having the reflector 42 and the substantially transparent polymer member 43 filled therein, in which all the light guide members 12, 23 and 30 are completely connected to one another in that order or completely integrated in a single unit. Reference is made to FIG. 24 showing a third embodiment of the present invention, in which FIG. 24 is a schematic perspective view. The surface illuminator of the third embodiment is a modification of the first embodiment described referring to e.g. FIG. 1 to FIG. 4. A surface lighting light guide member 32 in the third embodiment differs from the lighting light guide member 30 in the first embodiment, while the linear light guide member 10 and the channel light guide member 20 in the first and second embodiments are the same as that in the first embodiment, in which the same numerals are attached. As shown in FIG. 24, the surface illuminator is briefly composed of a light guide unit 120 and a LED 200 as a point source. The light guide unit 120 is composed of a linear light guide member 10 having a substantially triangular reflector 40 therein, a channel light guide member 20 having optical channel elements 21 (optical cores) and openings or air interposers (optical air clad) 22 and the surface lighting light guide member 32. In this embodiment, the surface lighting light guide member 32 is composed of a substantially rectangular and substantially transparent plate having a substantially planer surface lighting first major surface 32a and a tapered second major surface i.e. an inclined, wedge-like or slanted surface 32b or 32b′ opposed to the first major surface 32a, a light receiving side surface 32c i.e. light input side and another side surface 32d opposed to the light receiving side surface 32c. The surface lighting light guide member 32 has a variable thickness in which one type of the surface lighting light guide member 32 is provided with the tapered surface 32b indicated by a continuous line in FIG. 24 so that the surface lighting light guide member 32 varies in the thickness so as to decrease in a stepwise fashion from the light receiving side surface 32c toward the opposed side surface 32d, while the surface lighting light guide member 32 has a substantially uniform thickness as shown in e.g. FIG. 1 to FIG. 4. Instead, another type of the surface lighting light guide member 32 has the continuous tapered surface 32b′ indicated by a dotted or dashed line in FIG. 24 so that the surface lighting light guide member 32 varies in the thickness so as to decrease gradually in a continuous fashion from the light receiving side surface 32c toward the opposed side surface 32d. Due to the tapered surface 32b/32b′, the light reached the surface lighting surfaces 32a has the variable critical angle of the TIR that narrows in accordance with a distance from the light receiving side 32c toward the opposed side 32d, more volume of the light leaks from the surface lighting surfaces 32a in accordance with the distance so that light diffusing means 50 in e.g. FIG. 6 is not necessarily required. The air clads 22 may be replaced to the solid clads 25 as the second embodiment (e.g. FIG. 7, FIG. 10) in such a manner that the openings or spacing 22 of the air clads 22 is filled with a substantially transparent polymer having a refractive index lower than the refractive index of the optical channel elements 21. Reference is made to FIG. 25 through FIG. 28 showing a fourth embodiment of the present invention. FIG. 25 is a schematic exploded perspective view showing the fourth embodiment, FIG. 26 is a schematic exploded top view showing the fourth embodiment, FIG. 27 is a schematic top view a of the fourth embodiment and FIG. 28 is a schematic enlarged perspective view showing a channel light guide 26 in FIG. 25. Duplicated description may be omitted as much as possible in this embodiment in respect to the portions or elements denoted by the same reference numerals as in the embodiments described in detail hereinbefore. A surface illuminator of the fourth embodiment is composed of a light guide unit 121 and a LED 200. The lighting light guide unit 121 is composed of a plate-like linear light guide member 10 having a triangular reflector 40 with opposed reflecting surfaces 40a and 40b disposed near a center of the linear light guide member 10, a surface lighting light guide member 30 and a channel light guide member 26 having a plurality of channel elements 27 and a plurality of slit-like air clads 28. The channel light guide member 26 is positioned laterally between the linear light guide member 10 and the surface lighting light guide member 30 to be in substantially contact with or connected with one another. As shown in FIG. 28, the channel light guide member 26 may be composed of a plurality of the optical channel elements i.e. solid cores 27 (27-1, 27-2, . . . , and 27n, and 27-1′, 27-2′, . . . , and 27-n′) and a plurality of air interposers i.e. air clads 28 (28-c, and 28-1, 28-2, . . . , and 28n, and 28-1′, 28-2′, . . . , and 28-n′). The optical channel elements 27 are sandwiched by the adjacent air interposers 28, in which each of the optical channel elements 27 are separated to isolate optically by the adjacent air interposers 28. The optical channel elements 27 and the air interposers 28 are alternately aligned in substantially parallel in order to form a linear fiber optic array as a whole. Since the optical core channel elements 21 with a relatively high refractive index n1 (n1>1) are interposed between the air interposers or air clads 22 with the refractive index n2 (n2=1) lower than that of the optical core channel elements 21 along the lengthwise direction of the linear fiber optic array i.e. the channel light guide 20, a plurality of independent optical waveguides or solid light pipes 21 (21-1, 21-2, . . . and 21n, and 21-1′, 21-2′, . . . , and 21-n′). That independent optical waveguides or solid light pipes 21 are optically isolated to one another are formed in the channel light guide member or the linear fiber optic array 20. It should be noted that in this embodiment, each pitch “p′” between the adjacent optical channel elements 27 and each width “w1′” of the optical channel elements 27 are variably changed to increase in a stepwise or continuously fashion along the linear length of the channel light guide member 26 in accordance with, or in proportion to the distance from a center “c” of the channel light guide member 26 toward the end 26e and 26f thereof to form a gradation pattern, while each width “w2′” of substantially all the air interposers or air clads 28 is substantially equal to one another. However, in the channel light guide member 20 of the first embodiment as shown in FIG. 7 that differs from the channel light guide member 26 of the fourth embodiment, each pitch “p” between the adjacent optical channel elements 27 and each width “w2” of substantially all the air interposers 28 are variably changed to decrease in a stepwise or continuously fashion along the linear length of the channel light guide member 20 in proportion to the distance from a center “c” of the channel light guide member 20 toward the end 20e and 20f thereof to form a gradation pattern, while each width “w1” of the optical channel elements 21 is substantially equal to one another. The channel light guide member 26 in this embodiment differs from the channel light guide member 20 in the first embodiment in the constitution. However, an effect obtained by both channel light guide members 26 and 20 is equivalent such that these gradation patterns produce a substantially uniform light output along the length of the channel light guide member 26 or 20. In the fourth embodiment, the air interposers or air clads 28 may be filled with substantially transparent solid polymer material therein with a refractive index lower than the refractive index of the channel guide elements 27, as well as the refractive index of the solid clads 23 as shown in FIG. 8. In the fourth embodiment, the opening of the triangular reflector 40 may be filled with substantially transparent solid material with a refractive index lower than the linear light guide 10, as well as the solid filler of the reflector 42 as shown in FIG. 8. Before the fifth embodiment is described referring to FIG. 30A and FIG. 30B, the optical channel light guides 10 and 23 in the before-mentioned embodiments are described as bellow referring to FIG. 29. Referring to FIG. 29 illustrating an enlarged partial perspective view, showing the optical channel light guides 10 and 23 in the embodiments described in the above. As shown in FIG. 29, the optical channel light guides 20 and 23 are composed of the optical channel elements 21 and the interposers 22 or 25 alternately aligned to form the linear fiber optic array, in which each of the optical channel elements 21 and the interposers 22 or 25 have a substantially rectangular shape. Each of the optical channel elements 21 to act as optical cores of light pipes is composed of a substantially rectangular light entrance or input side surface 21c, a substantially rectangular light exit or output side surface 21d opposed to and in parallel with the entrance or input side surface 21c, a substantially rectangular first side wall 21h, a substantially rectangular second side wall I 21g opposed to and in parallel with the first side wall I 21h and opposed and parallel top and bottom surfaces, in which an area size of the light entrance and exit side surfaces 21c and 21d is substantially equal. Each of the air or solid interposers 22 or 25 to act as optical clads or claddings of light pipes is composed of a substantially rectangular first side surface 22c or 25c, a substantially rectangular second side surface 22d or 25d opposed to and in parallel with the first side surface 22c or 25c, the substantially rectangular first and second side walls and the substantially rectangular top and bottom surfaces, in which the first and second side walls are common portions with the first and second side walls 21g and 21h of the optical channel elements 21. When light transmitted within the linear light guide member 10 or 12 (see e.g. FIG. 1 and FIG. 16) reaches the light entrance side surfaces 21c of the optical channel elements 21, the light enters interiors of the optical channel elements 21, the light reflects at least one time based on the TIR at the side walls 21g and 21h and/or the top and bottom surfaces and the light exits from the light exit side surfaces 21d. When light transmitted within the linear light guide member 10 or 12 reaches the first side surfaces 22c or 25c of the clad interposers 22 or 25, the light with the angle more than the critical angle of the TIR is reflected at the first side surfaces 22c or 25c by the clad interposers 22 or 25 to return the linear light guide member 10 or 12 without entering the clad interposers 22 or 25, while the light with the angle less than the critical angle of the TIR enters interiors of the clad interposers 22 or 25 from the first side surfaces 22c or 25c and the light to exits from the second surfaces 22d or 25d. Therefore, substantially all volume of the light reached the light entrance side surfaces 21c of the optical channel elements 21 can pass effectively through the optical channel elements 21 to exit from the light exit surface 21d, while a volume of the light reached the first side surfaces 22c or 25c of the clad interposers 22 or 25 partially passes through the clad interposers 22 or 25 to exit from the second side surface 22d or 25d and the rest volume of the light returns the linear light guide member to transmit therein. Referring to FIG. 30A and FIG. 30B illustrating schematic perspective enlarged partial views showing the fifth embodiment having optical channel elements 21′ and 21″ having a substantially trapezoidal shape. As shown in FIG. 30A, the optical channel element 21′ to act as an optical core may be composed of a trapezoidal structure having a light entrance surface 21′c with a first surface area, a light exit surface 21′d with a second surface area larger than the first surface area, opposed to, parallel with the light entrance surface 21′c, a first side wall 21′g, a second side wall 21′h opposed to, nonparallel with the first side wall 21′g and opposed, parallel top and bottom surfaces. The first and second side walls 21′g and 21′h have inclined, sloped or slanted surfaces so that an surface area of the light exit side surfaces 21′d becomes larger in size than the surface area of the light entrance side surfaces 21′c. An interposer 22′ to act as an optical clad or cladding is composed of a trapezoidal structure having a first side surface 22′c with a first surface area, a second side surface 22′d with a second surface area smaller than the first surface area, opposed inclined, sloped or slanted side walls with an inclined angle “ag” and top and bottom surfaces, and the interposer 22′ is positioned between the walls 21′g and 21′h of the adjacent optical channel element 21′. Since the surface area of the light exit surface 21′d of the optical channel element 21′ is larger than the surface area of the light entrance surface 21′c of the optical channel element 21′, light entered from the light entrance surface 21′c to an interior of the optical channel element 21′ can exit from the light exit surface 21′d to expand its directivity with wide radiation angle. Therefore, the surface lighting light guide 30 in this embodiment, can receive the light with a more uniform brightness or luminance along the length of the light receiving side surface 30c thereof, than the surface lighting light guide 30 in the before-mentioned embodiments. As shown in FIG. 30B, the optical channel element 21″ to act as an optical core may be composed of a trapezoidal structure having a light entrance surface 21″c with a first surface area, a light exit surface 21″d with an opposed second surface area larger than the first surface area, opposed inclined, wedge-like or slanted side walls 21″e and top and bottom surfaces. An interposer 22″ to act as an optical clad or cladding is composed of a triangular structure having a first surface 22″c with a surface area, opposed inclined, wedge-like or slanted side walls, top and bottom surfaces and a crossed line 22″d to connect the opposed inclined, wedge-like or slanted side walls with an inclined angle “ag”, and the interposer 22″ is positioned between the walls 21″e of the adjacent optical channel element 21″. In this embodiment, the light entrance side surfaces 21″c of the adjacent optical channel elements 21″ are separated by the interposers 22″, while plural optical channel elements 21″ are connected to one another by a connection portion “cp” elongated from the light exit surface 21″d along a lengthwise direction in the light exit surface 21″d, therefore the channel light guide 20″ or 23″ form a linear continuous fiber optic channel integrated array, even if the interposers 22″ are air clads. Since the surface area of the light exit surface 21″d of the optical channel element 21″ is larger than the surface area of the light entrance surface 21″c of the optical channel element 21′, light entered from the light entrance surface 21″c to an interior of the optical channel element 21″ can exit from the continuous light exit surface 21″d to expand its directivity with wide radiation angle so that the surface lighting light guide 30 can receive the light with a more uniform brightness or luminance along the light receiving side surface 30c thereof. Referring to FIG. 31A and FIG. 31B illustrating a schematic enlarged partial top view showing the sixth embodiment showing surface illuminators having modified optical cores in optical channel light guides. In FIG. 31A, a light guide unit 101A is composed of a surface lighting light guide 30, an optical channel light guide 20A and a linear light guide 10, in which three light guides 30, 20A and 10 are laterally connected in that order to form an integrated composite unit. The optical channel light guide 20A is composed of a plurality of optical channel light guide elements (i.e. optical cores) 21A and a plurality interposers (i.e. optical clads) 22A having substantially transparent films 22Aa and air spacing 22Ab. The optical clads 22A, i.e. the transparent films 22Aa and the air 22Ab have a refractive index lower than the refractive index of the optical cores 21A and the linear light guide 10. The transparent clad films 22Aa are disposed on side walls of the optical cores 21A so that liquid polymer may be coated and hardened on the side walls of the optical cores 21A to form the transparent clad films 22Aa. When light rays L1 or L3 traveled within the linear light guide 10 reach to an interface between the front surfaces or front surface portions of the linear light guide 10 and the optical clads 22A (i.e. the transparent solid clad films 22Aa or the air 22Ab), the light rays L1 indicated as continuous lines in FIG. 31A reflect at the interface because the light rays L1 have more than a critical angle “cr”. While the light rays L3 indicated as dotted lines in FIG. 31A pass through the interface because the light rays L3 have less than the critical angle “cr”. When light rays L2 or L4 traveled within the linear light guide 10 enter each interior of the cores 21A and reach to interfaces of the transparent solid clad films 22Aa, the light rays L2 indicated as continuous lines in FIG. 31A reflect at least one time at the interface to opposite direction within the cores 21A and exit from exit surfaces or exit surface portions of the cores 21A into the surface lighting light guide or surface lighting light guide portions 30 because the light rays L2 have a light incident angle more than a critical angle “cr”. While the light rays L4 indicated as dotted lines in FIG. 31A pass through the solid clad films 22Aa and the air spacing 22Ab because the light rays L4 have a light incident angle less than the critical angle “cr”. In FIG. 31B showing a modification of the light guide unit 101A, light reflecting metallic films 22Ba to act as optical clads may be substitute for the transparent solid polymer clad films 22Aa in FIG. 31A. A light guide unit 101B is composed of a surface lighting light guide 30, an optical channel light guide 20B having optical cores 21B and optical clads 22B and a linear light guide 10, in which three light guides 30, 20B and 10 are laterally connected in that order to form an integrated composite unit. The light reflecting metallic films 22Ba are disposed on side walls of the optical cores 21B so as to be formed selectively on side walls of the optical cores 21B preferably by a vacuum plating process or non-electrolyte plating process using light reflecting metals such as silver or aluminum. When light rays L1 or L3 traveled within the linear light guide 10 reach to an interface between the front surfaces or front surface portions of the linear light guide 10 and the air clads 22Bb), the light rays L1 indicated as continuous lines in FIG. 31B reflect at the interface because the light rays L1 have a light incident angle more than a critical angle “cr”. While the light rays L3 indicated as dotted lines in FIG. 31B pass through the interface because the light rays L3 have a light incident angle less than the critical angle “cr” and the light rays L3 enter the air clads 22Bb and reflect at the light reflecting metallic films 22Ba to opposite direction. When light rays L2 and L4 traveled within the linear light guide 10 enter each interior of the cores 21B and reach to the light reflecting metallic films 22Ba i.e. metallic clads, the light rays light rays L2 indicated as continuous lines in FIG. 31B and the light rays light rays L4 indicated as dotted lines in FIG. 31B reflect at least one time at the light reflecting metallic films 22Ba to opposite direction within the cores 21B and exit from exit surfaces or exit surface portions of the cores 21B into the surface lighting light guide or surface lighting light guide portions 30. Therefore, he light rays with an arbitrary incident angle such as light rays L2 and L4 can transmit within the cores 21B without escaping from the side walls thereof and the light rays can exit from the light exit surface or exit surface portions thereof to enter the surface lighting light guide 30. Referring to FIG. 32A and FIG. 32B illustrating a schematic enlarged partial top view showing the sixth embodiment showing surface illuminators having modified optical channel light guides. In FIG. 32A, a light guide unit 101C is composed of a surface lighting light guide 30, an optical channel light guide 20C and a linear light guide 10, in which three light guides 30, 20C and 10 are laterally connected in that order to form an integrated composite unit. The optical channel light guide 20C may be composed of a plurality of optical channel light guide elements (i.e. optical cores) 21C and a plurality of clads 22C having substantially transparent polymer films 22Ca and air 22Cb. In this embodiment, the substantially transparent polymer films 22Ca may contain a plurality of light diffusing particles dispersed therein in which the light diffusing particles may be selected from transparent glass and polymer beads, gaseous bubbles having a refractive index different from the refractive index of the transparent films 22Ca, and light reflecting metallic particles such as aluminum or silver. The clads 22C, i.e. the transparent films 22Ca and the air 22Cb have a refractive index lower than the refractive index of the optical cores 21C and the linear light guide 10. The transparent films 22Ca with the light diffusing particles are disposed on side walls of the optical cores 21C so that transparent liquid polymer containing the light diffusing particles solid may be coated and hardened on the side walls of the optical cores 21A to form the transparent films 22Ca with the light diffusing particles. When light rays L1 or L3 traveled within the linear light guide 10 reach to an interface between the front surfaces or front surface portions of the linear light guide 10 and the optical clads (i.e. the transparent solid clad films 22Ca or the air 22Cb), the light rays L1 indicated as continuous lines in FIG. 32A reflect at the interface because the light rays L1 have more than a critical angle “cr”. While the light rays L3 indicated as dotted lines in FIG. 32A pass through the interface because the light rays L3 have less than the critical angle “cr” and the light rays L3 entered the air clad 22Cb further advance to the solid clad films 22Ca with diffusing particles where the light rays L3 diffuse to become diffused light L5. When light rays L2 or L4 traveled within the linear light guide 10 enter each interior of the cores 21C and reach to interfaces of the transparent films 22Ca with the light diffusing particles, the light rays L2 indicated as continuous lines in FIG. 32A reflect at least one time at the transparent films 22Ca to opposite direction within the cores 21C and exit from exit surfaces or exit surface portions of the cores 21C into the surface lighting light guide or surface lighting light guide portions 30 because the light rays L2 have more than a critical angle “cr”, while the light rays L4 indicated as dotted lines in FIG. 32A pass through the solid clads 22Ca and the air 22Cb because the light rays L4 have less than the critical angle “cr” In FIG. 32B showing a modification of the light guide unit 101A in FIG. 31A, a light guide unit 101D is composed of a surface lighting light guide 30, an optical channel light guide 20D and a linear light guide 10, in which three light guides 30, 20D and 10 are laterally connected in that order to form an integrated composite unit. The optical channel light guide 20D may be composed of a plurality of optical channel light guide elements 21D (i.e. optical cores 21D) and a plurality of clads 22D having air spacing 22Db and substantially transparent first and second polymer films 22Da and 22Dc, in which the transparent first polymer films 22Da are disposed on side walls of the optical cores 21D and the transparent second polymer films 22Dc are disposed on portions of front side surface of the linear light guide 10 to face the air spacing 22Db where optical cores 21D are not present. The clads 22D, i.e. the transparent polymer clad films 22Da and 22Dc and the air spacing 22Db have a refractive index lower than the refractive index of the optical cores 21D and the linear light guide 10. The transparent polymer clad films 22Da and 22Dc may be made so that liquid polymer or monomer may be coated and hardened on the side walls of the optical cores 21D and the portions of front side surface of the linear light guide 10. When light rays L1 or L3 traveled within the linear light guide 10 reach to an interface between the front surfaces or front surface portions of the linear light guide 10 and the transparent solid clad films 22Dc, the light rays L1 indicated as continuous lines in FIG. 32B reflect at the interface because the light rays L1 have more than a critical angle “cr”, while the light rays L3 indicated as dotted lines in FIG. 32B pass through the transparent solid clad films 22Dc and enter the air spacing 22Db because the light rays L3 have less than the critical angle “cr”. cores 21D and reach to interfaces of the transparent solid clad films 22Da, the light rays L2 indicated as continuous lines in FIG. 32B reflect at least one time at the side walls of the cores 21D to opposite direction within the cores 21D and exit from exit surfaces or exit surface portions of the cores 21D into the surface lighting light guide or surface lighting light guide portions 30 because the light rays L2 have more than a critical angle “cr”, while the light rays L4 indicated as dotted lines in FIG. 32B pass through the solid clads 22Da because the light rays L4 have less than the critical angle “cr” and the light rays enter the air spacing 22Db. Referring to FIG. 33A and FIG. 33B illustrating a schematic enlarged partial top view showing the sixth embodiment showing surface illuminators having modified optical cores in optical channel light guides. In FIG. 33A showing a modification of the light guide unit 101D in FIG. 32B, a light guide unit 101E is composed of a surface lighting light guide 30, an optical channel light guide 20E and a linear light guide 10, in which three light guides 30, 20E and 10 are laterally connected in that order to form an integrated composite unit. The optical channel light guide 20E may be composed of a plurality of optical channel light guide elements 21E (or optical cores) and a plurality of clads 22E having air 22Eb and first and second light reflecting metallic films 22Ea and 22Ec, in which the first light reflecting metallic films 22Ea are disposed on side walls of the optical cores 21E and the second light reflecting metallic films 22Ec are disposed on portions of front side surface of the linear light guide 10 to face the air space 22Eb where optical cores 21E are not present. The first and second light reflecting metallic films 22Ea and 22Ec may be preferably made by a non-electrolyte plating process or a vacuum plating process selectively on the side walls of the optical cores 21E and the portions of front side surface of the linear light guide 10 where the optical cores 21E are not present. When light rays L1 or L3 traveled within the linear light guide 10 reach to the second light reflecting metallic films 22Ec, the light rays L1 with incident angle “ra” indicated as continuous lines in FIG. 33A and the light rays L3 indicated as dotted lines in FIG. 33A reflect at the second light reflecting metallic films 22Ec to opposite direction within the linear light guide 10. When light rays L2 or L4 traveled within the linear light guide 10 enter each interior of the cores 21E and reach to the first light reflecting metallic films 22Ea, the light rays L2 with incident angle “ra” indicated as continuous lines in FIG. 33A and the light rays L4 indicated as dotted lines in FIG. 33A reflect at least one time at the first light reflecting metallic films 22Ea to opposite direction within the cores 21E and exit from exit surfaces or exit surface portions of the cores 21E into the surface lighting light guide or surface lighting light guide portions 30. In this embodiment, as described in the above, it is noted that all the light rays L1 and L3 can be reflected by the second metallic films 22Ec within the linear light guide 10 and also all the light rays L2 and L4 can be reflected at least one time by the first metallic films 22Ea within the optical cores 21E to exit into the surface lighting light guide 30. In FIG. 33B showing a combination of the light guide unit 101D in FIG. 32B and the light guide unit 101E in FIG. 33A, a light guide unit 101F is composed of a surface lighting light guide 30, an optical channel light guide 20F and a linear light guide 10, in which three light guides 30, 20F and 10 are laterally connected in that order to form an integrated composite unit. The optical channel light guide 20F may be composed of a plurality of optical channel light guide elements 21F (or optical cores) and a plurality of optical clads 22F having air spacing 22Fb, substantially transparent first and second polymer films 22Fa and 22Fc and first and second light reflecting metallic films 22Fd and 22Fe. The first polymer films 22Fa are disposed on side walls of the optical cores 21F, the second polymer films 22Fc are disposed on portions of front side surface of the linear light guide 10 to face the air spacing 22Fb where optical cores 21F are not present. The first and second light reflecting metallic films 22Fd and 22Fe are disposed on the first and second polymer films 22Fa and 22Fc respectively in that order. When light rays L1 or L3 traveled within the linear light guide 10 reach to the second polymer film 22Fc, the light rays L1 indicated as continuous lines in FIG. 33B reflect thereat because the light rays L1 have more than a critical angle “cr”, while the light rays L3 indicated as dotted lines in FIG. 32B pass through the transparent second polymer film 22Fc because the light rays L3 have less than the critical angle “cr” and then the light rays L3 are reflected by the second light reflecting metallic films 22Fe to return toward the linear light guide 10. When light rays L2 or L4 traveled within the linear light guide 10 enter each interior of the cores 21F and reach to interfaces with the transparent solid clad films 22Fa, the light rays L2 indicated as continuous lines in FIG. 33B reflect at least one time at the side walls of the cores 21D to opposite direction within the cores 21F and exit from exit surfaces or exit surface portions of the cores 21F into the surface lighting light guide or surface lighting light guide portions 30 because the light rays L2 have an incident angle more than a critical angle “cr”, while the light rays L4 indicated as dotted lines in FIG. 33B pass through the solid clads 22Fa because the light rays L4 have an incident angle less than the critical angle “cr” and the light rays L4 are reflected by the first light reflecting metallic films 22Fd to return within the cores 21F for exiting from the light exit surfaces of the cores 21F. Back to FIG. 31B, FIG. 33A and FIG. 33B, the metallic films 22Ba in FIG. 31B, 22Ea and 22Ec in FIGS. 33A and 22Fd and 22Fe in FIG. 33B may be partial reflective mirror or half mirror films instead, in which the partial reflective mirror or half mirror films have a desired reflectivity and transmittance that reflects and transmits light and the partial reflective mirror or half mirror thin films may be formed by a vacuum deposition process using e.g. Al, Ag, Cr and Au and a thickness of the partial reflective mirror or half mirror thin film may be from 0.001·m to 1·m. Referring to FIG. 34 illustrating a schematic exploded top view showing the ninth embodiment of the present invention, a surface illuminator is composed of a light guide unit 122 having a linear light guide member 10A, a channel light guide member 29 and a surface lighting light guide 30, and a plurality of LEDs 200-1, . . . , and 200n for point sources. The linear light guide member 10A is composed of a substantially transparent plate-like linear member having a plurality of light guide portions 10-1, . . . , and 10-n (where “n” is natural number) connected in series in a lengthwise direction thereof and a plurality of a substantially triangular openings to act as reflectors 40-1, . . . , 40n (where “n” is natural number) having opposed inclined reflecting side surfaces with substantially a letter “V” shape, in which the reflectors 40-1, . . . , and 40n are disposed within each center of the light guide portions 10-1, . . . , and 10-n. portions 20-1, . . . , and 20-n (n: natural number) connected in series in a lengthwise direction and each of the channel light guide portions 20-1, . . . , and 20-n is composed of channel light guide elements 21 having substantially transparent solid optical core members with a comparatively high refractive index and a plurality of air clads 22 having with a lower refractive index than the refractive index of the channel light guide elements 21, in which the channel light guide elements 21 and the air clads 22 are alternately aligned to form a linear array. Each of the LEDs 200-1, . . . , and 200-n (n: natural number) is positioned in contact with, adjacent to or buried in the linear light guide member 13 to face the opposed inclined surfaces of the reflector 40-1, . . . , and 40-n. Each of the light guide portions 10-1, . . . , and 10-n with the reflectors 40-1, . . . , and 40n may be the same structure and configuration as the linear light guide member 10 in the first embodiment as shown in e.g. FIG. 1 and FIG. 2. The surface lighting light guide 30 may have a uniform thickness similarly to the surface lighting light guide 30 as shown in e.g. FIG. 1 or may have a variable thickness similarly to the surface lighting light guide 32 as shown in FIG. 24. The surface illuminator 122 (200-1, . . . , and 200-n) in this embodiment can produce a surface lighting with a larger size and a brighter surface luminance than that of the surface illuminator (100 and 200) in the first embodiment. Reference is made to FIG. 35 through FIG. 38 showing a tenth embodiment of the present invention, in which FIG. 35 is a schematic exploded top view showing the tenth embodiment of the present invention, showing a modification of the reflector shown in e.g. FIG. 1 in the first embodiment and FIG. 36 through FIG. 38 is schematic top views showing three types of configuration of the tenth embodiment. In FIG. 35, a surface illuminator is composed of a substantially transparent light guide unit 123 and LED/LEDs 200, in which the light guide unit 123 is composed of a linear light guide member 13, a channel light guide member 20 having optical channel elements i.e. solid cores 21 and air interposers 22 i.e. air clads and a surface lighting light guide member 30. The linear light guide member 13 is composed of opposed major surfaces, opposed rear and front side surfaces 13c and 13d and opposed end surfaces 13e and 13f. The rear side surface 13d has opposed reflecting side surfaces 44a and 44b therein near a center thereof, in which the opposed reflecting surfaces 44a and 44b act as a reflector or reflecting portion 44 forming a substantially “V” shape of a letter or character (as indicated to be surrounded by a circle with a dotted circular line in FIG. 35). The front side surface 13c has a light receiving portion near a center thereof, where a LED 200 is positioned in contact therewith or adjacent thereto so as to face the opposed reflecting surfaces 44a and 44b of the reflector 44 through the linear light guide member 13, in which an optical axis of LED 200 coincides a cross point of the opposed surfaces 44a and 44b. The channel light guide member 20 is composed of optical channel elements i.e. solid cores 21 (21-1, . . . 21-n, and 21-1′, . . . , 21-n′) (“n” and “n′”: natural number) and air interposers i.e. air clads 22 (22-c, 22-1, . . . , 22-n and 22-1′, . . . , 22-n′) (“n” and “n′”: natural number). Each of the optical channel elements 21 may have a substantially equal width and substantially equal light input side surface area and each of the interposers 22 may have a substantially variable width. The optical channel elements 21 and the air interposers 22 are alternately aligned in parallel to one another so as to form a linear fiber optic channel array, in which the optical channel elements 21 are distributed variably in a pitch therebetween in a stepwise or continuous manner to form a gradation pattern in such a manner that a distributed density of the channel elements 21 increases from a center of the channel light guide member 20 toward both of the end surfaces 20e and 20f thereof as shown in FIG. 35. Therefore, the light emitted from LED 200 enters the linear light guide member or portion 13, reflects at the reflector 40, advances to substantially opposed lateral directions within the linear light guide member or portion 13, enters the channel light guide member or portion 20 and then the light can exit therefrom with a substantially uniform luminance along the length thereof. Thereby, a surface lighting with substantially uniform surface luminance or brightness can be produced over substantially entire areas of the surface lighting surface 30a in the surface lighting light guide member or portion 30. As shown in FIG. 36, a first type of the light guide unit 123A is composed of the surface lighting light guide member 30 and a composite light guide member 13/20 of the linear light guide member or portion 13 having the reflector 44 and the channel light guide member or portion 20, in which the linear light guide member or portion 13 and the channel light guide member or portion 20 are connected and integrated to form a single unit. The composite light guide member 13/20 is disposed relative to the surface lighting light guide member 30 in such a manner that the light exit side surface 20d of the channel light guide portion 20 of the composite light guide member 13/20 may be positioned in contact with the light receiving side surface or light input side surface 30c of the surface lighting light guide member 30. As shown in FIG. 37, a second type of the light guide unit 123B is composed of the linear light guide member 13 and a composite light guide member 20/30 of the surface lighting light guide member 30 and the channel light guide member 20, in which the surface lighting light guide member 30 and the channel light guide member 20 are connected and integrated to form a single unit. The composite light guide member 20/30 may be disposed relative to the linear light guide member 13 in such a manner that the light entrance side surface 20c of the channel light guide portion 20 in the composite light guide member 13/20 may be positioned in contact with the front side surface 13d of the linear light guide member 13. As shown in FIG. 38, a third type of the light guide unit 123C is composed of a single composite member 13/20/30, in which the surface lighting light guide member or portion 30, the channel light guide member or portion 20 and the linear light guide member or portion 13 are connected and completely integrated to form a single unit. Reference is made to FIG. 39 through FIG. 42 showing an eleventh embodiment of the present invention, in which FIG. 39 is a schematic exploded top view and FIG. 40, FIG. 41 and FIG. 42 are schematic top views showing three types of light guide units. In FIG. 39, a surface illuminator of the eleventh embodiment is composed of a substantially transparent light guide unit 124 and a LED 200, in which the light guide unit 124 is composed of a linear light guide member 13, a channel light guide member 26 having optical channel elements (i.e. solid cores) 27 and air interposers (i.e. air clads) 28 and a surface lighting light guide member 30. The linear light guide member 13 is composed of at least opposed major surfaces, opposed rear and front surfaces 13c and 13d and opposed end surfaces 13e and 13f. The front side surface 13d includes opposed reflecting side surfaces 44a and 44b thereon near a center thereof, in which the opposed reflecting side surfaces 44a and 44b act as a reflector or reflecting portion 44 forming a substantially “V” shape of a letter or character (as indicated to be surrounded by a circle with a circular dotted line FIG. 39. The rear side surface 13c includes light receiving portion near a center thereof, where LED 200 is positioned in contact therewith or adjacent thereto so as to face the opposed reflecting surfaces 44a and 44b of the reflector 44 through the linear light guide member 13, in which an optical axis of LED 200 coincides a cross point of the opposed surfaces 44a and 44b. The channel light guide member 26 is composed of optical channel elements i.e. solid cores 27 (27-1, . . . , 27-n, and 27-1′, . . . , 27-n′) (n and n′: natural number) and air interposers i.e. air clads 28 (28-c, 28-1, . . . , 28-n and 28-1′, . . . , 28-n′) (n and n′: natural number). Each of the optical channel elements 27 may be composed of a variable width, while each of the interposers 28 may be composed of a substantially equal width and equal light input surface area except for the center interposer 28-c. The optical channel elements 27 and the air interposers 28 are alternately aligned in parallel to one another so as to form a linear fiber optic channel array, in which the optical channel elements 27 are distributed variably in a pitch therebetween. Each width of the optical channel elements 27 variably increases in a stepwise or continuously fashion along the linear length of the channel light guide member 26 in proportion to the distance from a center of the channel light guide member 26 toward the end surfaces 26e and 26f thereof to form a gradation pattern, while each width of the air interposers 28 is substantially equal to one another. The optical channel elements 27 and the air interposers 28 are alternately aligned in parallel to one another so as to form a linear fiber optic channel array, in which the optical channel elements 27 are distributed variably in a pitch therebetween. Each width of the optical channel elements 27 variably increases in a stepwise or continuously fashion along the linear length of the channel light guide member 26 in accordance with the distance from a center of the channel light guide member 26 toward the end surfaces 26e and 26f thereof to form a gradation pattern, while each width of the air interposers 28 is substantially equal to one another except for the center interposer 28-c. Therefore, the light emitted from LED 200 enters the linear light guide member or portion 13, reflects at the reflector 40, advances to substantially opposed lateral directions within the linear light guide member or portion 13, enters the channel light guide member or portion 26 and then the light can exit therefrom with a substantially uniform luminance along the length thereof. Thereby, a surface lighting with substantially uniform surface luminance or brightness can be produced over substantially entire areas of the surface lighting surface 30a in the surface lighting light guide member or portion 30. As shown in FIG. 40, a first type of the light guide unit 124A is composed of the surface lighting light guide member 30 and a composite light guide member 13/26 of the linear light guide member or portion 13 having the reflector 44 and the channel light guide member or portion 26, in which the linear light guide member or portion 13 and the channel light guide member or portion 26 are connected and integrated to form a single unit. The composite light guide member 13/26 may be disposed relative to the surface lighting light guide member 30 in such a manner that the light exit side surface 26d of the composite light guide member 13/26 may be positioned in contact with the light receiving side surface or light input side surface 30c of the surface lighting light guide member 30. As shown in FIG. 41, a second type of the light guide unit 124B is composed of the linear light guide member 13 having the reflector 44 and a composite light guide member 26/30 of the surface lighting light guide member 30 and the channel light guide member 26, in which the surface lighting light guide member 30 and the channel light guide member 26 are connected and integrated to form a single unit. The composite light guide member 26/30 may be disposed relative to the linear light guide member 13 in such a manner that the light entrance side surface 26c of the channel light guide portion 26 in the composite light guide member 26/30 may be positioned in contact with the front side surface 13d of the linear light guide member 13. As shown in FIG. 42, a third type of the light guide unit 124C is composed of a single composite member 13/26/30, in which the surface lighting light guide member or portion 30, the channel light guide member or portion 26 and the linear light guide member or portion 13 are connected and completely integrated to form a single unit. Reference is made to FIG. 43 through FIG. 48, in which these Figures are schematic partial enlarged top views showing several modifications of the reflectors 40 in e.g. FIG. 1, FIG. 5 and the reflectors 44 in e.g. FIG. 35 to FIG. 38. Referring to FIG. 43, a surface illuminator is composed of a light guide unit 100 and a LED, in which the light guide unit 100 is composed of a surface lighting light guide 30, optical channel light guide 20 having solid cores 21 and air clads 22 and 22-c and a linear light guide 10 having a substantially triangular reflector 40 being laterally connected to one another in that order to form a single integrated unit. The substantially triangular reflector 40 is composed of a substantially rectangular opening having opposed side surfaces 40a and 40b with “V” shaped configuration and a substantially transparent polymer film or layer 41 disposed on the opposed side surfaces 40a and 40b, in which a refractive index of the substantially transparent polymer film or layer 41 is lower than the refractive index of the linear light guide 10. A light diffusing film or layer may be substituted for the substantially transparent polymer film or layer 41, in which the light diffusing film or layer is composed of the substantially transparent film or layer 41 and a plurality of light diffusing particles dispersed therein. When light from LED 200 reaches the light diffusing film or layer, the light incident to the opposed side surfaces 40a and 40b with an incident angle lower than a critical angle of the TIR is diffused by the light diffusing particles therein to advance with wide spread angle toward an upward direction or toward the center air interposer 22-c, while the light opposed side surfaces 40a and 40b with an incident angle more than the critical angle is reflected by the light diffusing film or layer to advance laterally within the linear light guide member or portion 10. A light reflecting, mirror, partial reflective mirror or half-mirror film may be substituted for the substantially transparent polymer film or layer 41, in which the light reflecting, mirror or half-mirror film may be composed of light reflecting metallic thin film using reflecting metal such as silver, aluminum or nickel that is selectively formed only on the opposed reflecting side surfaces 40a and 40b by non-electrolyte plating, vacuum evaporation (i.e. vacuum metallization) or sputtering process. The light reflecting, mirror, partial reflective mirror or half-mirror film controls the light incident thereto, in which the light reflects at the film to lateral directions within the linear light guide member 10 and/or the light passes through the film to an upward direction in accordance with the reflectance and/or transmittance of the film. Referring to FIG. 44, a surface illuminator is composed of a light guide unit 123 and a LED 200, in which the light guide unit 123 is composed of a surface lighting light guide 30, optical channel light guide 20 having solid cores 21 and air clads 22 and 22-c and a linear light guide 13 having a substantially “V” shaped reflector 44 being laterally connected to one another in that order to form a single integrated unit. The substantially “V” shaped reflector 44 is composed of opposed side surfaces 44a and 44b with “V” shaped configuration and a substantially transparent polymer film or layer 45 disposed on the opposed side surfaces 44a and 44b, in which a refractive index of the substantially transparent polymer film or layer 45 is lower than the refractive index of the linear light guide 13. A light diffusing film or layer may be substituted for the substantially transparent polymer film or layer 45, in which the light diffusing film or layer is composed of the substantially transparent film or layer 45 and a plurality of light diffusing particles dispersed therein. When light from LED 200 reaches the light diffusing film or layer, the light with an incident angle lower than a critical angle of the TIR is diffused by the light diffusing particles therein to advance with wide spread angle toward an upward direction or toward the center air interposer 22-c, while the light with an incident angle more than the critical angle is reflected by the light diffusing film or layer to advance laterally within the linear light guide member or portion 13. A light reflecting, mirror, partial reflective mirror or half-mirror film may be substituted for the substantially transparent polymer film 45, in which the light reflecting, mirror, partial reflective mirror or half-mirror film 45 may be composed of light reflecting metallic thin film using reflecting metal such as silver, aluminum or nickel that is selectively formed only on the opposed side surfaces 44a and 44b by non-electrolyte plating, vacuum evaporation (i.e. vacuum metallization) or sputtering process. The light reflecting, mirror, partial reflective mirror or half-mirror film controls the light incident thereto, in which the light reflects at the film to advance toward lateral directions within the linear light guide member 13 and/or the light passes through the film to advance toward an upward direction or toward the center air interposer 22-c in accordance with the reflectance and/or transmittance of the film. Referring to FIG. 45, a surface illuminator is composed of a light guide unit 100 and a LED 200, in which the light guide unit 100 is composed of a surface lighting light guide 30, optical channel light guide 20 having solid cores 21 and air clads 22 and 22-c and a linear light guide 10 having a substantially triangular reflector 42 being laterally connected to one another in that order to form a single integrated unit, in which this substantially triangular reflector 42 is a modification of substantially triangular reflector 40 in FIG. 43. The substantially triangular reflector 44 may be composed of opposed side surfaces 42a and 42b with substantially parabolic or curved shape and an optional light adjusting film 43 disposed on the substantially parabolic or curved, opposed side surfaces 42a and 42b. The optional light adjusting film 43 may be selected from a substantially transparent polymer film with a refractive index lower than the refractive index of the linear light guide 10, the substantially transparent polymer film containing light diffusing particles therein or a light reflecting/mirror/partial reflective mirror/half mirror film. Referring to FIG. 46, a surface illuminator is composed of a light guide unit 123 and a LED 200, in which the light guide unit 123 is composed of a surface lighting light guide 30, optical channel light guide 20 having solid cores 21 and air clads 22 and 22-c and a linear light guide 13 having a substantially “V” shaped reflector 46 being laterally connected to one another in that order to form a single integrated unit. The substantially triangular reflector 46 may be composed of opposed side surfaces 46a and 46b with substantially parabolic or curved shape and an optional light adjusting film 47 disposed on the substantially parabolic or curved, opposed side surfaces 46a and 46b. The optional light adjusting film 47 may be selected from a substantially transparent polymer film with a refractive index lower than the refractive index of the linear light guide 13, the substantially transparent polymer film containing light diffusing particles therein and a light reflecting, mirror, partial reflective mirror or half-mirror film with a predetermined reflectance and/or transmittance. Referring to FIG. 47, a surface illuminator is composed of a light guide unit 100 and a LED 200, in which the light guide unit 100 is composed of a surface lighting light guide 30, optical channel light guide 20 having solid cores 21 and air clads 22 and 22-c and a linear light guide 10 having a substantially triangular reflector 48 being laterally connected to one another in that order to form a single integrated unit. Referring to FIG. 48, a surface illuminator is composed of a light guide unit 123 and a LED 200, in which the light guide unit 123 is composed of a surface lighting light guide 30, optical channel light guide 20 having solid cores 21 and air clads 22 and 22-c and a linear light guide 13 having a substantially “V” shaped reflector 48′ being laterally connected to one another in that order to form a single integrated unit. In FIG. 47 and FIG. 48, a reflector 48 or 48′ may be composed of opposed side surfaces (48a and 48b) or (48′a and 48′b) having substantially “V” shaped configuration and an optional light adjusting film 49 or 49′ disposed entirely or partially on the opposed side surfaces (48a and 48b) or (48′a and 48′b). The optional light adjusting film 49 or 49′ may be selected from a substantially transparent polymer film with a refractive index lower than the refractive index of the linear light guide 10 or 13, the substantially transparent polymer film containing light diffusing particles therein and a light reflecting, mirror or half-mirror film with a predetermined reflectance and/or transmittance. The substantially “V” shaped side surfaces (48a and 48b) or (48′a and 48′b) are composed of inclined side surfaces and substantially horizontal side surfaces to connect the adjacent inclined side surfaces so as to form a stepwise configuration as a whole. When light emitting from LED 200 reaches the substantially “V” shaped side surfaces (48a and 48b) or (48′a and 48′b), the light incident to the inclined faces reflects mostly toward substantially lateral direction within the linear light guide member 10 or 13, while light incident to the substantially horizontal faces passes mostly therefrom to the central air clad 22-c or to the light adjusting film 49 or 49′. Reference is made to FIG. 49, FIG. 50A and FIG. 50B showing a twelfth embodiment of the present invention, in which FIG. 49 is a schematic exploded perspective view, FIG. 50A is a schematic top view showing a linear light guide member 14 and FIG. 50B is a schematic cross sectional view showing the linear light guide member 14 taken along the line D—D in FIG. 49. As shown in FIG. 49, a surface illuminator of this embodiment is composed of a light guide unit 131 having a linear light guide member 14, a channel light guide member 20 and a surface lighting light guide member 30, and a LED 200. The channel light guide member 20 is composed of a plurality of optical channel elements i.e. solid cores 21 and a plurality of air interposers i.e. air clads 22 disposed therebetween, in which the optical channel elements 21 form a linear array, as described in detail hereinbefore. The channel light guide member 20 is composed of a plurality of optical channel elements i.e. solid cores 21 and a plurality of air interposers i.e. air clads 22 laterally disposed therebetween to form a fiber optic linear array, as described in detail hereinbefore. As shown in FIG. 49, FIG. 50A and FIG. 50B, the linear light guide member 14 is composed of a substantially transparent linear light guide member having opposed major surfaces 14a and 14b elongated linearly, opposed side surfaces 14c and 14d elongated linearly and opposed end surfaces 14e and 14f. The major surface i.e. top surface 14a is further composed of substantially planer or flat dual surfaces and inclined (i.e. wedge-like or slanted) opposed surface 60 (60a and 60b) positioned therebetween near a center of the major surface 14a, in which the opposed surfaces 60 (60a and 60b) is acting as the reflector 60 having a substantially “V” shaped configuration. A light reflecting film or layer 61 (61a, 61b, 61c and 61d) may be preferably formed on the inclined opposed surfaces 60 (60a and 60b) and portions of the planer surfaces extended from the inclined opposed surfaces 60, in which the reflecting film or layer 61 may be made of reflecting metal such vacuum evaporated silver or aluminum. The linear light guide member 14 may have a grooved portion 14g (i.e. cavity, housing space or room) disposed on a center of the major surface i.e. bottom surface 14b so as to house at least light emitting portion of the LED 200. The LED 200 may be adhered to the grooved portion 14g by a substantially transparent polymer adhesive 62 such as substantially transparent epoxy resin for optical adhesive purpose, in which the substantially transparent polymer adhesive 62 may preferably have a refractive index similar to or the same as the refractive index of the linear light guide member 14. Reference is made to FIG. 51 and FIG. 52 showing a thirteenth embodiment of the present invention, in which FIG. 51 is a schematic exploded perspective view and FIG. 52 is a schematic top view. Referring to FIG. 51 and FIG. 52, a surface illuminator of this embodiment is composed of a light guide unit 132 and a LED 200, in which the light guide unit 132 is composed of a linear light guide member 15, a channel light guide member 60 and a surface lighting light guide member 30. The linear light guide member 15 is composed of a substantially transparent linear light guide member having opposed major surfaces 15a and 15b elongated linearly, opposed side surfaces 15c and 15d elongated linearly and opposed end surfaces 15e and 15f. In this embodiment, the linear light guide member 15 has not the substantially triangular reflector 40, 42, 44, 48, 48′ or 60 in the embodiments described herein before. The LED 200 is disposed relative to the end surface 15f, so that the LED 200 is positioned adjacent to, in contact with the end surface 15f and a reflecting film, sheet or plate 64 is disposed adjacent to, in contact with the end surface 15e opposed to the end surface 15f. The channel light guide member 60 is composed of a plurality of optical channel elements i.e. solid cores 21 and a plurality of air interposers i.e. air clads 22, so that the optical channel elements 21 and the air interposers 22 are alternately aligned in parallel to form a fiber optic linear array. As shown in FIG. 52, the optical channel elements 21 have a substantially equal width “w1”, while the air interposers 22 have a substantially variable width “w2”, in which the air interposers 22 are distributed to form a gradation pattern such that the width “w2” decreases in a stepwise fashion (or a continuous fashion) from the end surface 15f where the LED 200 is positioned toward the end surface 10e where the reflecting means 63 is positioned. The optical channel elements 21A are distributed in such a way that a pitch “p” between the adjacent optical channel elements 21 decreases in accordance with a distance from the end surface 15e toward the opposed end surface 15f, in which the pitch “p” means a distance between the midpoints of the width “w1” of the adjacent optical channel elements 21. Reference is made to FIG. 53 that is a top view showing a fourteenth embodiment of the present. As shown in FIG. 53, a surface illuminator of this embodiment is composed of a light guide unit 133 and a LED 200, in which the light guide unit 133 is composed of a linear light guide member 15, a channel light guide member 61 and a surface lighting light guide member 30. The light guide unit 133 in this embodiment differs from the light guide unit 132 of the thirteenth embodiment shown in FIG. 51 and FIG. 52 in the channel light guide member 61, while the linear light guide member 15 and the surface lighting light guide member 30 are the same as that of the thirteenth embodiment. The linear light guide member or portion 15 is composed of a substantially transparent linear light guide member or portion having opposed major surfaces elongated linearly, opposed side surfaces 15c and 15d elongated linearly and opposed end surfaces 15e and 15f. The LED 200 is disposed relative to the end surface 15f, so that the LED 200 is positioned adjacent to, in contact with the end surface 15f and a reflecting means 64 such as a reflecting film, sheet or plate is disposed adjacent to, in contact with the end surface 15e opposed to the end surface 15f. The channel light guide member 61 is composed of a plurality of optical channel elements i.e. solid cores 62 and a plurality of air interposers i.e. air clads 63 disposed therebetween, in which the optical channel elements 62 and the air interposers 63 are alternately aligned laterally and in parallel to form a fiber optic linear array. As shown in FIG. 53, the optical channel elements 62 are distributed to have a substantially variable width “w1” and also the air interposers 63 are distributed to have a substantially variable width “w2”, along the fiber optic linear array. The optical channel elements 62 and the air interposers 63 are distributed in the fiber optic linear array to form a gradation pattern in such a way that the width “w1” of the optical channel elements 62 and the width “w2” of the air interposers 63 change oppositely in that size in a stepwise fashion (or a continuous fashion) from the end surface 15f near the LED 200 toward the opposed end surface 10e near the reflecting means 63, so that the width “w1” of the optical channel elements 62 increases in proportion to a distance from the end surface 15f to the end surface 15e, while the width “w2” of the air interposers 63 decreases in proportion to a distance from the end surface 15f to the opposed end surface 15e. Light emitting from LED 200 via the end surfaces 15f enters the linear light guide member or portion 15 via the end surface 15f and the light travels to reflect repeatedly between the opposed side surfaces 15c and 15d, and between the opposed major surfaces so as to advance towards the opposed end surfaces 15d linearly along the length of the linear light guide member or portion 15. When a portion of a second light reaches the front side surface portion 63c of the air interposers 63 with an incident angle more than a critical angle, the light reflects at the front side surface portion 63c to return within the linear light guide member or portion 15. When the rest portion of the second light reaches the front side surface portion 63c of the air interposers 63 with an incident angle less than the critical angle, the light enters the air interposers 63 and passes therethrough. The linear light guide member 15 in this embodiment, a distance or width between the opposed rear and front side surfaces 15c and 15d is substantially equal along the length of the linear light guide member 15, however a linear tapered light guide member 16 indicated by a chain or un-continuous line in FIG. 53 may be substituted for the linear light guide member 15 indicated by a continuous line. The linear tapered light guide member 16 has an inclined i.e. slanted rear surface 16c and a horizontal front surface 16d opposed to each other and the distance or width between the rear and front surfaces 16c and 16d and decreases gradually from the end surface 15f near the LED 200 to the end surface 15e near the reflecting means 64. Reference is made to FIG. 54 showing a fifteenth embodiment of the present invention, in which FIG. 54 is a schematic top view showing the fifteenth embodiment. As shown in FIG. 54, a surface illuminator of this embodiment is composed of a light guide unit 134 and two LEDs 200a and 200b, in which the light guide unit 134 is composed of a linear light guide member 15, a channel light guide member 65 and a surface lighting light guide member 30. The linear light guide member or portion 15 is composed of a substantially transparent linear light guide member or portion having opposed major surfaces elongated linearly, opposed side surfaces 15c and 15d elongated linearly. The first LED 200a is disposed adjacent to or in contact with the first end surface 15e and the second LED 200b is disposed adjacent to or in contact with the second end surface 15f. The channel light guide member 65 is composed of a plurality of optical channel elements i.e. solid cores 66 and a plurality of air interposers i.e. air clads 67 disposed therebetween, in which the optical channel elements 66 and the air interposers 67 are alternately aligned laterally and in parallel to form a fiber optic linear array. As shown in FIG. 54, the optical channel elements 66 are distributed to have a substantially variable width “w1” and also the air interposers 67 are distributed to have a substantially variable width “w2”, along the fiber optic linear array. The optical channel elements 66 and the air interposers 67 are distributed in the fiber optic linear array 65 to form a gradation pattern in such a way that the width “w1” of the optical channel elements 66 and the width “w2” of the air interposers 67 change oppositely in that size in a stepwise fashion (or a continuous fashion) from both of the opposed end surface 15e and 15f toward a substantially a center “c” of the linear light guide member or portion 15, so that the width “w1” of the optical channel elements 62 increases in proportion to a distance from the end surfaces 15e and 15f to the center “c”, while the width “w2” of the air interposers 67 decreases in proportion to a distance from the end surface 15f the center “c”. The linear light guide member 15 in this embodiment, a distance or width between the opposed rear and front side surfaces 15c and 15d is substantially equal along the length of the linear light guide member 15, however a linear tapered light guide member 17 indicated by a chain or un-continuous line in FIG. 53 may be substituted for the linear light guide member 15 indicated by a continuous line. The linear light guide member 17 has an inclined or slanted rear surface 17c and a horizontal front surface 17d opposed to each other, in which the distance or width between the inclined rear surface 17c and the horizontal front side surface 17d decreases gradually from the end surfaces 15e and 15f toward the center “c”. Reference is made to FIG. 55 showing a sixteenth embodiment of the present invention, in which FIG. 55 is a schematic top view showing the sixteenth embodiment. As shown in FIG. 55, a surface illuminator of this embodiment is composed of a light guide unit 135 and a LED 200, in which the light guide unit 135 is composed of a linear light guide member 15, a channel light guide member 68 and a surface lighting light guide member 30. The linear light guide member or portion 15 is composed of a substantially transparent linear light guide member or portion having opposed major surfaces, a tapered, inclined, sloped or slanted rear side surface 15c, a front side surface 15d opposed to the rear side surface 15c, a first end surface 15e and a second end surface 15f where a LED 200 is positioned, in which a distance between the tapered rear side surface 15c and the non-tapered front surface 15d decreases gradually from the second end surface 15f toward the first end surface 15e, in which the critical angle of incident light within the linear tapered light guide 15 decreases according to the distance from the second surface 15f. The channel light guide member 68 is composed of a plurality of optical channel elements 68-1 and a plurality of air interposers or slit-like openings 68-2 disposed therebetween, in which the optical channel elements 68-1 and the air interposers 68-2 are alternately aligned laterally in parallel to form a linear optical channel array. It is noted that all the optical channel elements 68-1 in this embodiment have a substantially equal width “w1” and also all the air interposers 68-2 have a substantially equal width “w2” as shown in FIG. 56, that differ from the optical channel light guides in the embodiments as mentioned in the above. Some light entered from the second end surface 15f transmits to reflect repeatedly between the tapered rear surface 15c and bottom surfaces 68-2c of the air interposers 68-2 in accordance with the total internal reflection (TIR) until incident light is less than the critical angle. Another light entered from the second end surface 15f transmits within the linear tapered light guide 15 and the light reached the light entrance surface 15c enters the channel light guide elements 68-1 because a refractive index of the channel light guide elements 68-1 is the same as or higher than the refractive index of the tapered light guide 15 so that the light entered the channel light guide elements 68-1 exits from the light exit side surfaces or portions to enter the surface lighting light guide 30. Reference is made to showing a seventeenth embodiment of the present invention, in which FIG. 56 is a schematic top view showing the seventeenth embodiment. As shown in FIG. 56, a surface illuminator of this embodiment is composed of a light guide unit 136 and a LED 200, in which the light guide unit 136 is composed of a linear light guide member 15, a channel light guide member 69 and a surface lighting light guide member 30. The linear light guide member or portion 15 is composed of a substantially transparent linear light guide member or portion having opposed major surfaces, a tapered, inclined, sloped or slanted rear side surface 15c, a front side surface 15d opposed to the rear side surface 15c, a first end surface 15e and a second end surface 15f where a LED 200 is positioned, in which a distance between the tapered rear side surface 15c and the non-tapered front surface 15d decreases gradually from the second end surface 15f toward the first end surface 15e, in which the critical angle of incident light within the linear tapered light guide 15 decreases according to the distance from the second surface 15f. The channel light guide member 69 is composed of a plurality of optical channel elements 69-1 and a plurality of solid interposers or transparent polymer interposers 69-2 disposed therebetween, in which the optical channel elements 69-1 and the solid interposers 69-2 are alternately aligned laterally in parallel to form a linear optical channel array, in which a refractive index of the optical channel elements 69-1 is higher than the refractive index of the solid interposers 69-2. It is noted that all the optical channel elements 69-1 in this embodiment have a substantially equal width “w1” and also all the solid interposers 69-2 have a substantially equal width “w2” as shown in FIG. 56, that differ from the optical channel light guides in the embodiments as mentioned in the above. Some light entered from the second end surface 15f transmits to reflect repeatedly between the tapered rear surface 15c and bottom surfaces 69-2c of the solid interposers 69-2 in accordance with the total internal reflection (TIR) until incident light is less than the critical angle. Another light entered from the second end surface 15f transmits within the linear tapered light guide 15 and the light reached the light entrance surface 15c enters the channel light guide elements 69-1 because a refractive index of the channel light guide elements 69-1 is the same as or higher than the refractive index of the tapered light guide 15 so that the light entered the channel light guide elements 69-1 exits from the light exit side surfaces or portions to enter the surface lighting light guide 30. Reference is made to FIG. 57 through FIG. 59 showing an eighteenth embodiment of the present invention, which is a modification of the first embodiment. FIG. 57 is a schematic exploded perspective view showing a surface illuminator of the eighteenth embodiment, FIG. 58 is a schematic exploded top view showing the surface illuminator of the eighteenth embodiment and FIG. 59 is a schematic top view showing the surface illuminator of the eighteenth embodiment. As shown in FIG. 57 through FIG. 59, a surface illuminator is briefly composed of a light guide unit 137 and at least one LED 200. The light guide unit 137 is made of a light transmitting member having a substantially transparent material. The light guide unit 137 is composed of a surface lighting light guide member 30, a linear light guide member or portion 69 and an optical channel light guide member or portion 20 disposed therebetween, in which the optical channel light guide member or portion 20 is sandwiched laterally by the linear light guide member 69 and the surface lighting light guide member 30. The optical channel light guide member 20 and the surface lighting light guide member 30 are similar to or the same as that described in mentioned above in detail in the first embodiment, a detail description on these members 20 and 30 is omitted here. The channel light guide or optical channel light guide member 20 is composed of a plurality of optical channels or optical channel elements 21 aligned in parallel to form a linear array, in which the optical channel elements 21 are isolated or separated to one another by interposers or slit-like openings 22 between the dual optical channel elements 21 adjacent to each other. The optical channel elements 21 are, similar to that of the first embodiment, variably distributed in quantity along the linear length of the channel light guide member 20 in proportion to the distance from a center “c” of the channel light guide plate 20 toward the opposed ends 20e and 20f. The linear light guide member 69 is, similarly to that of the first embodiment, composed of opposed major surfaces, opposed front and rear side surfaces 69c and 69d, opposed end surfaces 69e and 69f, at least one light receiving portion 69g in the rear side surface 69c and a reflector 40 having opposed reflecting surfaces to form a letter “V” shaped configuration. The rear side surface 69c, different from that of the first embodiment, is further composed of first and second inclined, wedge-like or slanted surfaces 69c and 69c′, in which the inclined, wedge-like or slanted surfaces 69c and 69c′ are inclined, wedge-like in a continuous fashion (or a stepwise fashion) from a center “c” of the linear light guide member 69 toward the opposed end surfaces 69e and 69f, thereby the rear side surface 69c forms a letter “V” shape. At least one LED 200 may be disposed relative to the linear light guide member 69 at the light receiving portion 69g thereof so that a light emitting surface 200 faces the light reflector 40. As shown in FIG. 60, the light guide unit 137 may be composed of a completely integrated composite unit, in which the surface lighting light guide member 30, the optical channel light guide member 20 and the linear guide member 69 are connected to one another. Instead, the light guide unit 137 may be composed of the linear guide member 69 and a composite unit of the surface lighting light guide member 30 and the optical channel light guide member 20, or composed of the surface lighting light guide member 30 and another composite unit of the linear guide member 69 and the optical channel light guide member 20. Reference is made to FIG. 60 through FIG. 64 showing a nineteenth embodiment of the present invention, in which includes a nonlinear light guide member with a letter or character “L” shaped configuration. FIG. 60 is a schematic exploded perspective view, FIG. 61 is a schematic exploded top view showing a surface illuminator, FIG. 62 is a schematic top view showing a first type of the surface illuminator, FIG. 63 is a schematic top view showing a second type of the surface illuminator and FIG. 64 is a schematic top view showing a third type of the surface illuminator. As shown in FIG. 60 and FIG. 61, the surface illuminator is briefly composed of a light guide unit 138 and at least one LED 200. The light guide unit 138 is made of a light transmitting member having a substantially transparent material. The light guide unit 138 is composed of a surface lighting light guide member 30, a nonlinear light guide member or portion 70 and an optical channel light guide member or portion 80 disposed therebetween, in which the optical channel light guide member or portion 80 is sandwiched laterally by the nonlinear light guide member 70 and the surface lighting light guide member 30. The nonlinear light guide member 70 has a substantially “L” shaped configuration with an angle of about 90 degree as a whole, in which the nonlinear light guide member 70 is composed of a substantially linear first light guide member 71, a substantially linear second light guide member 72 connected with the first light guide member 71, a light receiving side surface, portion or area 73 and a reflector 40 having opposed reflecting surfaces or portions 40a and 40b with a substantially “V” shaped configuration. The substantially linear first light guide member 71 further composed of opposed major surfaces 71a and 71b, opposed front and rear side surfaces 71c and 71d and an end surface 71e. The substantially linear second light guide member 72 further composed of opposed major surfaces 72a and 72b, opposed front and rear side surfaces 72c and 72d and an end surface 72e, which is similar to the substantially linear first light guide member 71. The opposed reflecting surfaces or portions with “V” shape 40a and 40b are positioned in a vicinity of a cross point of the opposed front side surfaces 71d and 72d. The light receiving side surface, portion or area 73 are positioned in a vicinity of a cross point of the rear side surfaces 71c and 72c, in which LED 200 is disposed in contact with or adjacent to the light receiving side surface, portion or area 73 so as to face the opposed reflecting surfaces 40a and 40b. The optical channel light guide member, channel light guide or channel light guide portion 80 has an “L” shaped configuration as a whole, similar to the nonlinear light guide member or distributing light guide 70. The optical channel light guide member 80 is composed of a plurality of optical channels or first and second optical channel elements 81 and 81′ to act as optical cores and a plurality of first and second interposers 82 and 82′ to act as optical clads disposed therebetween, in which the optical channel elements 81 and 81′ have a refractive index higher than the refractive index of the interposers 82 and 82′. The first optical channel elements 81 (81-1, 81-2, . . . , 81-n) and the first interposers 82 (82-1, 82-2, . . . , 82-n) are alternately aligned in contact with and in parallel to one another to form a first linear array and the second optical channel elements 81′ (81′-1, 81′-2, . . . , 81′-n), similarly, the second interposers 82′ (82′-1, 82′-2, . . . , 82′-n) are alternately aligned in contact with and in parallel to one another to form a second linear array. The first and second linear arrays are connected with or in contact with a “V” shaped center interposer 82c to form a nonlinear array with “L” shaped configuration, in which the optical channel elements 81 and 81′ are isolated or separated to one another by the interposers 82 and 82′ between the dual optical channel elements 81 and 81′ adjacent to each other. The optical channel elements 81 and 81′, similarly to that of the first embodiment, are variably distributed in quantity along the nonlinear length of the channel light guide member 80 in proportion to the distance from a center of the channel light guide member 80 toward the opposed ends 71e and 72e. The interposers 82 and 82′, similarly to that of the first embodiment, are variably decreased in that width along the nonlinear length of the interposers 82 and 82′ in proportion to the distance from a center of the channel light guide member 80 toward the opposed ends 71e and 72e. LED 200 may be disposed relative to the nonlinear light guide member 70 at the light receiving portion 73 thereof so that a light emitting surface of the LED 200 faces the light reflector 40, i.e. the opposed reflecting surfaces 40a and 40b. As shown in FIG. 62, a first type of the light guide unit 138A may be composed of a completely integrated composite light guide unit 30/80/70, in which the surface lighting light guide member 30 (or the surface lighting light guide portion), the optical channel light guide member 80 (or the optical channel light guide portion) and the nonlinear light guide member 70 (or the nonlinear light guide portion) are connected to one another in that order. Instead, as shown in FIG. 63, a second type of the light guide unit 138B may be composed of the surface lighting light guide member 30 and a composite light guide unit 70/80 of the optical channel light guide member 80 and the nonlinear light guide member 70 connected therewith, while the optical channel light guide member 80 that is a portion of the composite light guide unit 70/80 is in contact with the surface lighting light guide member 30. Instead, as shown in FIG. 64, a third type of the light guide unit 138C may be composed of the nonlinear light guide member 70 and a composite light guide unit 30/80 of the optical channel light guide member 80 and the surface lighting light guide member 30 connected therewith, while the optical channel light guide member 80 that is a portion of the composite light guide unit 30/80 is in contact with the nonlinear light guide member 70. Back to FIG. 62, a fourth type of the surface lighting light guide member 30, the optical channel light guide member 80 and the nonlinear light guide member 70 may be separated to one another, in which three members 30, 80 and 70 may be disposed in contact with to one another in that order. Reference is made to FIG. 65 and FIG. 66 showing a twentieth embodiment of the present invention. FIG. 65 is a schematic exploded perspective view showing a surface illuminator of the twentieth embodiment and FIG. 66 is a schematic top view showing the surface illuminator in the FIG. 66. As shown in FIG. 65 and FIG. 66, a surface illuminator is briefly composed of a light guide unit 139 and at least one LED 200. The light guide unit 139 is made of a light transmitting member having a substantially transparent material. The light guide unit 139 is composed of a surface lighting light guide member 30, a nonlinear light guide member or portion 70′ and an optical channel light guide member or portion 80 disposed therebetween, in which the optical channel light guide member or portion 80 is sandwiched laterally by the nonlinear light guide member 70′ and the surface lighting light guide member 30. The nonlinear light guide member 70′ has a substantially “L” shaped configuration with an angle of about 90 degree as a whole, in which the nonlinear light guide member 70′ (i.e. distributing light guide) is composed of a substantially linear first light guide member 71′, a substantially linear second light guide member 72′ connected with the first light guide member 71′, a light receiving side surface, portion or area 73 and a reflector 40 having opposed reflecting surfaces or portions 40a and 40b with a substantially “V” shaped configuration. It is noted that the substantially nonlinear light guide member 70′ in this embodiment has the first and second substantially linear light guide members 71′ and 72′ having a tapered configuration, in which a distance between rear side surfaces 71′c and 72′c and front side surfaces 71′d and 72′d decreases from a center of the substantially nonlinear light guide member 70′ toward ends thereof 71′e and 72′e, while the substantially nonlinear light guide member 70 in the fifteenth embodiment has a parallel configuration as shown in FIG. 61 through FIG. 63, in which a distance between rear side surfaces 71c and 72c and front side surfaces 71d and 72d substantially unchanged or equal from a center of the substantially nonlinear light guide member 70 toward ends thereof 71e and 72e. In FIG. 66, the light guide unit 30/80/70′ is composed of the surface lighting light guide 30, the channel light guide 80 and “L” shaped tapered nonlinear light guide 70′, in which three light guides 30, 80 and 70′ are connected to one another in that order to form a single integrated composite unit. However, three light guides 30, 80 and 70′ may be separated to be in contact with in that order to one another, or two light guides of the three light guides 30, 80 and 70′ may form a composite. Reference is made to showing a twenty first embodiment of the present invention, in which FIG. 67 is a schematic exploded perspective view showing a surface illuminator of the twenty first embodiment and FIG. 68 is a schematic top view showing the surface illuminator in the FIG. 67, which includes a nonlinear light guide member with a letter or character “L” shaped configuration. This embodiment is typically a modification of the embodiment as shown in FIG. 60 through FIG. 66. As shown in FIG. 67 and FIG. 68, the surface illuminator is briefly composed of a light guide unit 139A and two numbers or sets of LED 200a and 200b. The light guide unit 139A is made of a light transmitting member having a substantially transparent material. The light guide unit 139A is composed of a surface lighting light guide member 30, a nonlinear light guide member or portion 70 and an optical channel light guide member or portion 59 disposed therebetween, in which the optical channel light guide member or portion 59 is sandwiched laterally by the nonlinear light guide member 70 and the surface lighting light guide member 30. The nonlinear light guide member 70 has a substantially “L” shaped configuration with an angle of about 90 degree as a whole, in which the nonlinear light guide member 70′ is composed of a substantially linear first light guide portion 71, a substantially linear second light guide portion 72 and a corner surface 73.to connect the linear first and second portions 73. The substantially linear first light guide member 71 further composed of opposed front and rear side surfaces 71c and 71d and an end surface 71e. The substantially linear second light guide member 72 further composed of opposed front and rear side surfaces 72c and 72d and an end surface 72e, which is similar to the substantially linear first light guide member 71. The LED 200a and 200b are disposed in contact with or adjacent to the end surfaces 71e and 72e so that each light emitting surface of the LED 200a and 200b faces the end surfaces 71e and 72e. The optical channel light guide member 59 is composed of a substantially linear first optical channel light guide portion 59-1 and a substantially linear second optical channel light guide portion 59-2, in which the first and second optical channel light guide portion 59-1 and 59-2 are disposed to have an angle of about 90 degree to form a substantially “L” shaped configuration. Each of the first and second optical channel light guide portion 59-1 and 59-2 is composed of a plurality of first and second optical channels elements 59-1a and 59-2a to act as optical cores and a plurality of first and second interposers 59-1b and 59-2b to act as optical clads disposed therebetween, in which the optical channel elements 59-1a and 59-2a have a refractive index higher than the refractive index of the interposers 59-1b and 59-2b. In this embodiment, as shown in FIG. 67 and FIG. 68, air with value “1” of the refractive index is used as the interposers 59-1b and 59-2b, however solid interposers may be used instead. The first optical channel elements 59-1a and the first interposers 59-1b are alternately aligned in parallel to one another to form a first linear array and the second optical channel elements 59-2a and the second interposers 59-2b are alternately aligned in contact with and in parallel to one another to form a second linear array, in which the first and second arrays form a nonlinear array having a substantially “L” shaped configuration as a whole. The optical channel elements 59-1a and 59-2a are variably distributed along the nonlinear length of the channel light guide member 59 in such a manner that a width of the optical channel elements 59-1a and 59-2a increases in proportion to the distance from the end surfaces 59-1e and 59-2e toward the corner side surface 70h. On the contrary, the interposers 59-1b and 59-2b variably distributed along the nonlinear length of the channel light guide member 59 in such a manner that a width of the interposers 59-1b and 59-2b decreases in proportion to the distance from the end surfaces 59-1e and 59-2e toward the corner side surface 70h. In FIG. 68, the light guide unit 139A is composed of the surface lighting light guide 30, the substantially “L” shaped channel light guide member 59 and the substantially “L” shaped distributing light guide 71, in which three light guides 30, 59 and 71 are connected one another in that order to form a single integrated composite unit. However, three light guides 30, 59 and 71 may be separated to be in contact with in that order to one another, or two light guides of the three light guides 30, 59 and 71 may form a composite, instead. As shown in FIG. 67 and FIG. 68, a modification of the distributing light guide 70 is indicated as a first chain line 71′ and a second chain line 72′, in which the modified distributing light guide has slanted rear surfaces thereof so that the distance between the rear and front surfaces decreases from the end surfaces 71-e and 72-e toward the corner surface 73. Reference is made to FIG. 69 and FIG. 70 showing a twenty second embodiment of the present invention. FIG. 69 is a schematic exploded perspective view showing a surface illuminator of the twenty second embodiment and FIG. 70 is a schematic top view showing the surface illuminator in the FIG. 69. As shown in FIG. 69 and FIG. 70, a surface illuminator is briefly composed of a light guide unit 140 and at least one LED 200, in which the surface illuminator of this embodiment is a modification of the embodiment as shown in FIG. 35 through FIG. 38. The light guide unit 140 is made of a light transmitting member having a substantially transparent material. The light guide unit 140 is composed of a surface lighting light guide member 30, a nonlinear light guide member or portion 74 and an optical channel light guide member or portion 83 disposed therebetween, in which the optical channel light guide member or portion 83 is sandwiched laterally by the nonlinear light guide member 74 and the surface lighting light guide member 30. The nonlinear light guide member 74 is acting as a distributing light guide for distributing light along an entire length thereof, in which the light is introduced from one limited area 73 thereof that is a corner surface area where LED 200 is positioned. The nonlinear light guide member 74 is composed of a substantially “U” shaped light guide member having a substantially linear first leg portion 74-1, a substantially linear second leg portion 74-2 opposed to and parallel with the first leg portion 74-1 and a substantially linear bottom portion 74-3 connected with a first slanted side surface 74i of the first leg portion 74-1 and a second slanted side surface 74h of the second leg portion 74-2. The first and second leg portions 74-1 and 74-2 have end surfaces 74-1e and 74-2e that are optically opposed to each other via an entire length of “U” shaped light guide 74. The substantially linear bottom portion 74-3 is provided with a reflector 40 near a center thereof in a front side surface 74-3d, in which the reflector 40 is composed of opposed reflecting surfaces or portions 40a and 40b with a substantially “V” shaped configuration that is one portion of the front side surface 74-3d. The LED 200 is disposed in contact with, adjacent to a rear side surface 74-3d near a center thereof in the substantially linear bottom portion 74-3 so that a light emitting window of the LED 200 faces the opposed reflecting surfaces 40a and 40b of the reflector 40. The channel light guide or optical channel light guide member 83 is composed of a opposed linear first and second leg portions and a bottom linear portion connected with the linear first and second leg portions to form a substantially “U” shaped configuration as a whole similar to the configuration of the distributing light guide 74, in which an external contour with “U” shape of the channel light guide 83 is substantially equal in size to an internal contour with “U” shape of the distributing light guide 74 so as to be connected or in contact with to each other. An internal contour with “U” shape of the channel light guide 83 is substantially equal in size to an contour with “U” shape of three adjacent side surfaces 30c, 30e and 30f of the surface lighting light guide 30 so as to be connected or in contact with to each other. The channel light guide or optical channel light guide member 83 is further composed of a plurality of optical channel elements 84 and a plurality of interposers 85, in which the optical channel elements 84 and the adjacent interposers 85 are alternately aligned so as to form a substantially “U” shaped array as a whole, in such a manner that each of the optical channel elements 84 is positioned to be sandwiched by the adjacent interposers 85. The interposers 85 are composed of a light transmitting solid member having a substantially transparent material having a refractive index lower than the refractive index of the optical channel elements 84. The interposers 85 may substitute air for the light transmitting solid member since the refractive index (value=1) of the air is generally lower than that of the light transmitting solid member such as PMMA or PC. Each of the optical channel elements 84 has a substantially equal width and equal light input surface area, while each of the interposers 85 has a substantially variable width. The optical channel elements 84 are distributed variably in a pitch therebetween in a stepwise or continuous manner to form a gradation pattern in such a manner that the quantity of the channel elements 84 is increased from a center of the bottom portion 74-3 (or the slanted side surfaces 74i and 74h toward both of the end surfaces 74-1e and 74-2e, while the interposers 85 are distributed variably in the width in a stepwise or continuous manner to form a gradation pattern in such a manner that the width of the interposers 85 is decreased from a center of the bottom portion 74-3 (or the slanted side surfaces 74i and 74h toward both of the end surfaces 74-1e and 74-2e. Therefore, light emitting from LED 200 to input into the nonlinear light guide member or portion 74 with “U” shaped configuration can output the light with a substantially uniform luminance along an entire length of the light output side surface or side surface portion 74-1d, 74-2d and 74-3d and resultantly a lighting with substantially uniform surface luminance or brightness can be produced from substantially entire areas of the surface lighting surface 30a of the surface lighting light guide member or portion 30. In FIG. 69 and FIG. 70, the light guide unit 140 is composed of the surface lighting light guide 30, the substantially “U” shaped channel light guide 83 and the substantially “U” shaped nonlinear distributing light guide 74, in which three light guides 30, 83 and 74 are connected one another in that order to form a single integrated composite unit. However, three light guides 30, 83 and 74 may be separated to be in contact with in that order to one another, or two light guides of the three light guides 30, 83 and 74 may form a composite, instead. Reference is made to FIG. 71 and FIG. 72 showing a twenty third embodiment of the present invention. FIG. 71 is a schematic exploded perspective view showing a surface illuminator of the twenty third embodiment and FIG. 72 is a schematic top view showing the surface illuminator in the FIG. 71. As shown in FIG. 71 and FIG. 72, a surface illuminator is briefly composed of a light guide unit 141 and at least one LED 200, in which the surface illuminator of this embodiment is a modification of the embodiment as shown in FIG. 69 and FIG. 70. The light guide unit 141 is made of a light transmitting member having a substantially transparent material. The light guide unit 141 is composed of a surface lighting light guide member 30, a nonlinear light guide member or portion 74′ and an optical channel light guide member or portion 83 disposed therebetween, in which the optical channel light guide member or portion 83 is sandwiched laterally by the nonlinear light guide member 74′ and the surface lighting light guide member 30. The nonlinear light guide member 74′ is acting as a distributing light guide for distributing light along an entire length thereof, in which the light is introduced from one limited area thereof. The nonlinear light guide member 74′ is composed of a substantially “U” shaped light guide member having a substantially linear first leg portion 74′-1, a substantially linear second leg portion 74′-2 opposed to and parallel with the first leg portion 74′-1 and a substantially linear bottom portion 74′-3 connected with a first slanted side surface 74′i of the first leg portion 74′-1 and a second slanted side surface 74′h of the second leg portion 74′-2. The first and second leg portions 74′-1 and 74′-2 have end surfaces 74′-1e and 74′-2e that are optically opposed to each other via an entire length of “U” shaped light guide 74′. The substantially linear bottom portion 74′-3 is provided with a reflector 40 near a center thereof in a front side surface 74′-3d, in which the reflector 40 is composed of opposed reflecting surfaces or portions 40a and 40b with a substantially “V” shaped configuration that is one portion of the front side surface 74′-3d. LED 200 is disposed in contact with, adjacent to a rear side surface 74′-3d near a center thereof in the substantially linear bottom portion 74′-3 so that a light emitting window of the LED 200 faces the opposed reflecting surfaces 40a and 40b of the reflector 40. The channel light guide or optical channel light guide member 83 is composed of a opposed linear first and second leg portions and a bottom linear portion connected with the linear first and second leg portions to form a substantially “U” shaped configuration as a whole similar to the configuration of the distributing light guide 74′, in which an external contour with “U” shape of the channel light guide 83 is substantially equal in size to an internal contour with “U” shape of the distributing light guide 74′ so as to be connected or in contact with to each other. An internal contour with “U” shape of the channel light guide 83 is substantially equal in size to an contour with “U” shape of three adjacent side surfaces 30c, 30e and 30f of the surface lighting light guide 30 so as to be connected or in contact with to each other. The channel light guide or optical channel light guide member 83 is further composed of a plurality of optical channel elements 84 and a plurality of interposers 85, in which the optical channel elements 84 and the adjacent interposers 85 are alternately aligned so as to form a substantially “U” shaped array as a whole, in such a manner that each of the optical channel elements 84 is positioned to be sandwiched by the adjacent interposers 85. The interposers 85 are composed of a light transmitting solid member having a substantially transparent material having a refractive index lower than the refractive index of the optical channel elements 84. The interposers 85 may substitute air for the light transmitting solid member since the refractive index (value=1) of the air is generally lower than that of the light transmitting solid member such as PMMA or PC. Each of the optical channel elements 84 has a substantially equal width and equal light input surface area, while each of the interposers 85 has a substantially variable width. The optical channel elements 84 are distributed variably in a pitch therebetween in a stepwise or continuous manner to form a gradation pattern in such a manner that the quantity of the channel elements 84 is increased from a center of the bottom portion 74′-3 (or the slanted side surfaces 74′i and 74′h toward both of the end surfaces 74′-1e and 74′-2e, while the interposers 85 are distributed variably in the width in a stepwise or continuous manner to form a gradation pattern in such a manner that the width of the interposers 85 is decreased from a center of the bottom portion 74′-3 (or the slanted side surfaces 74′i and 74′h toward both of the end surfaces 74′-1e and 74′-2e. Therefore, light emitting from LED 200 to input into the nonlinear light guide member or portion 74 with “U” shaped configuration can output the light with a substantially uniform luminance along an entire length of the light output side surface or side surface portion 74′-1d, 74′-2d and 74′-3d and resultantly a lighting with substantially uniform surface luminance or brightness can be produced from substantially entire areas of the surface lighting surface 30a of the surface lighting light guide member or portion 30. It is noted that each of the first and second opposed light guides 74′-1 and 74′-2 and the bottom light guide 74′-3 has a tapered configuration, in which the first and second opposed light guides 74′-1 and 74′-2a have tapered rear side surfaces 74′-1c and 74′-2c and the bottom light guide 74′-3 has a tapered rear side surface 74′-3c, in which the distance between the tapered rear side surfaces 74′-1c and 74′-2c and the non-tapered front side surfaces 74′-1d and 74′-2d decreases from the corner sides 74′1 and 74′h toward the end surfaces 74′-1e and 74′-2e and the distance between the tapered rear side surface 74′-3c and the front side surfaces 74′-3d decreases from near the center of the bottom light guide 74′-3 toward the corner sides 74′1 and 74′h. On the contrary, in the nineteenth embodiment as shown in FIG. 70 and FIG. 71, the distance between the rear and front side surfaces of the first and second leg light guides 74-1 and 71-2 are substantially equal or uniform and the distance between the rear and front side surfaces of the bottom light guide 74-3 is substantially equal or uniform except for a portion of the reflector 40. In FIG. 71 and FIG. 72, the light guide unit 141 is composed of the surface lighting light guide 30, the substantially “U” shaped channel light guide 83 and the substantially “U” shaped nonlinear distributing light guide 74′, in which three light guides 30, 83 and 74′ are connected one another in that order to form a single integrated composite unit. However, three light guides 30, 83 and 74′ may be separated to be in contact with in that order to one another, or two light guides of the three light guides 30, 83 and 74′ may form a composite, instead. Reference is made to FIG. 73 and FIG. 74 showing a twenty fourth embodiment of the present invention. FIG. 73 is a schematic exploded perspective view showing a surface illuminator of the twenty fourth embodiment and FIG. 74 is a schematic top view showing the surface illuminator in the FIG. 73. As shown in FIG. 73 and FIG. 74, a surface illuminator is briefly composed of a light guide unit 142 and two LEDs 200a and 200b, in which the surface illuminator of this embodiment is a modification of the fifteenth embodiment as shown in FIG. 61 through FIG. 65. The light guide unit 142 is made of a light transmitting member having a substantially transparent material. The light guide unit 142 is composed of a surface lighting light guide member 30, a nonlinear light guide member or portion 75 and an optical channel light guide member or portion 86 disposed therebetween, in which the optical channel light guide member or portion 86 is sandwiched laterally by the nonlinear light guide member 75 and the surface lighting light guide member 30. The nonlinear light guide member 75 is acting as a distributing light guide for distributing light along an entire nonlinear length thereof, in which the light is introduced from two limited areas thereof that are two corner side surfaces 75i and 75h where LEDs 200a and 200b are positioned so as to be in contact with or adjacent to the corner surfaces 75i and 75h. The nonlinear light guide member 75 is composed of a substantially “U” shaped light guide member having a substantially linear first leg portion 75-1, a substantially linear second leg portion 75-2 opposed to and parallel with the first leg portion 75-1 and a substantially linear bottom portion 75-3 connected with a first slanted side surface 75i of the first leg portion 75-1 and a second slanted side surface 75h of the second leg portion 75-2. The first and second leg portions 75-1 and 75-2 have end surfaces 75-1e and 75-2e that are optically opposed to each other via an entire length of “U” shaped light guide 75. The channel light guide or optical channel light guide member 86 is composed of opposed linear first and second leg portions 86-1 and 86-2 and a bottom linear portion 86-3 connected with the linear first and second leg portions to form a substantially “U” shaped configuration as a whole similar to the configuration of the distributing light guide 75, in which an external contour with “U” shape of the channel light guide 86 is substantially equal in size to an internal contour with “U” shape of the distributing light guide 75 so as to be connected or in contact with to each other. An internal contour with “U” shape of the channel light guide 86 is substantially equal in size to an contour with “U” shape of three adjacent side surfaces 30c, 30e and 30f of the surface lighting light guide 30 so as to be connected or in contact with to each other. The channel light guide or optical channel light guide member 86 is further composed of a plurality of optical channel elements 87 and a plurality of interposers 88, in which the optical channel elements 87 and the adjacent interposers 88 are alternately aligned so as to form a substantially “U” shaped array as a whole, in such a manner that each of the optical channel elements 87 is positioned to be sandwiched by the adjacent interposers 88. The interposers 88 are composed of a light transmitting solid member having a substantially transparent material having a refractive index lower than the refractive index of the optical channel elements 87. The interposers 88 may substitute air for the light transmitting solid member since the refractive index (value=1) of the air is generally lower than that of the light transmitting solid member such as PMMA or PC. Each of the optical channel elements 87 has a substantially equal width and equal light input surface area, while each of the interposers 88 has a substantially variable width. The optical channel elements 87 are distributed variably in a pitch therebetween in a stepwise or continuous manner to form a first gradation pattern in such a manner that the quantity of the channel elements 87 is increased from the dual corners of the bottom portion 86-3 of the channel light guide portion 86 toward the dual end surfaces of the first and second leg portions 86-1 and 86-2 and from the dual corners of the bottom portion 86-3 toward a center of the bottom portion 86-3. The interposers 88 are distributed variably in the width in a stepwise or continuous manner to form a second gradation pattern in such a manner that the width of the interposers 88 is decreased f from the dual corners of the bottom portion 86-3 of the channel light guide portion 86 toward the dual end surfaces of the first and second leg portions 86-1 and 86-2 and from the dual corners of the bottom portion 86-3 toward a center of the bottom portion 86-3. Therefore, light emitting from LEDs 200a and 200b to input into the nonlinear light guide member or portion 75 with “U” shaped configuration can output the light with a substantially uniform luminance along an entire length of the light output side surface or side surface portions of the distributing light guide 75 and resultantly a lighting with substantially uniform surface luminance or brightness can be produced from substantially entire areas of the surface lighting surface 30a of the surface lighting light guide member or portion 30. In FIG. 73 and FIG. 74, the light guide unit 142 is composed of the surface lighting light guide 30, the “U” shaped channel light guide 86 and “U” shaped nonlinear distributing light guide 75, in which three light guides or light guide portions 30, 86 and 75 are connected one another in that order to form a single integrated composite unit. However, three light guides 30, 86 and 75 may be separated to be in contact with in that order to one another, or two light guides of the three light guides 30, 86 and 75 may form a composite, instead. Reference is made to FIG. 75 and FIG. 76 showing a twenty fifth embodiment of the present invention. FIG. 75 is a schematic exploded perspective view showing a surface illuminator of the twenty fifth embodiment and FIG. 76 is a schematic top view showing the surface illuminator in the FIG. 75. As shown in FIG. 75 and FIG. 76, a surface illuminator is briefly composed of a light guide unit 143 and two LEDs 200a and 200b, in which the surface illuminator of this embodiment is a modification of the twenty fourth embodiment as shown in FIG. 74 and FIG. 75. The light guide unit 143 is made of a light transmitting member having a substantially transparent material. The light guide unit 143 is composed of a surface lighting light guide member 30, a nonlinear light guide member or portion 76 and an optical channel light guide member or portion 86 disposed therebetween, in which the optical channel light guide member or portion 86 is sandwiched laterally by the nonlinear light guide member 76 and the surface lighting light guide member 30. The nonlinear light guide member 76 is acting as a distributing light guide for distributing light-along an entire nonlinear length thereof, in which the light is introduced from two limited areas thereof that are two corner side surfaces 76i and 76h where LEDs 200a and 200b are positioned so as to be in contact with or adjacent to the corner surfaces 76i and 76h. The nonlinear light guide member 76 is composed of a substantially “U” shaped light guide member having a substantially linear first leg portion 76-1, a substantially linear second leg portion 76-2 opposed to and parallel with the first leg portion 76-1 and a substantially linear bottom portion 76-3 connected with a first slanted side surface 76i of the first leg portion 76-1 and a second slanted side surface 76h of the second leg portion 76-2. The first and second leg portions 76-1 and 76-2 have end surfaces 76-1e and 76-2e that are optically opposed to each other via an entire length of “U” shaped light guide 76. It is noted that each of the first and second opposed light guides 76-1 and 76-2 and the bottom light guide 76-3 has a tapered configuration, in which the first and second opposed light guides 76-1 and 76-2 have tapered rear side surfaces and the bottom light guide 76-3 has a tapered rear side surface, in which the distance between the tapered rear side surfaces 76-1c and 76-2c and the non-tapered front side surfaces 76-1d and 76-2d decreases from the corner sides 76i and 76h toward the end surfaces 76-1e and 76-2e and the distance between the tapered rear side surface 76-3c and the front side surface 76-3d decreases from the corner sides 76l and 76h toward the center of the bottom light guide 76-3. On the contrary, in the twenty first embodiment as shown in FIG. 74 and FIG. 75, the distance between the rear and front side surfaces of the first and second leg light guides 76-1 and 76-2 are substantially equal or uniform and the distance between the rear and front side surfaces of the bottom light guide 76-3 is substantially equal or uniform. The channel light guide or optical channel light guide member 86 is composed of opposed linear first and second leg portions 86-1 and 86-2 and a bottom linear portion 86-3 connected with the linear first and second leg portions to form a substantially “U” shaped configuration as a whole similar to the configuration of the distributing light guide 76, in which an external contour with “U” shape of the channel light guide 86 is substantially equal in size to an internal contour with “U” shape of the distributing light guide 76 so as to be connected or in contact with to each other. An internal contour with “U” shape of the channel light guide 86 is substantially equal in size to an contour with “U” shape of three adjacent side surfaces 30c, 30e and 30f of the surface lighting light guide 30 so as to be connected or in contact with to each other. The channel light guide or optical channel light guide member 86 is further composed of a plurality of optical channel elements 87 and a plurality of interposers 88, in which the optical channel elements 87 and the adjacent interposers 88 are alternately aligned so as to form a substantially “U” shaped array as a whole, in such a manner that each of the optical channel elements 87 is positioned to be sandwiched by the adjacent interposers 88. The interposers 88 are composed of a light transmitting solid member having a substantially transparent material having a refractive index lower than the refractive index of the optical channel elements 87. The interposers 88 may substitute air for the light transmitting solid member since the refractive index (value=1) of the air is generally lower than that of the light transmitting solid member such as PMMA or PC. Each of the optical channel elements 87 has a substantially equal width and equal light input surface area, while each of the interposers 88 has a substantially variable width. The optical channel elements 87 are distributed variably in a pitch therebetween in a stepwise or continuous manner to form a first gradation pattern in such a manner that the quantity of the channel elements 87 is increased from the dual corners of the bottom portion 86-3 of the channel light guide portion 86 toward the dual end surfaces of the first and second leg portions 86-1 and 86-2 and from the dual corners of the bottom portion 86-3 toward a center of the bottom portion 86-3. The interposers 88 are distributed variably in the width in a stepwise or continuous manner to form a second gradation pattern in such a manner that the width of the interposers 88 is decreased f from the dual corners of the bottom portion 86-3 of the channel light guide portion 86 toward the dual end surfaces of the first and second leg portions 86-1 and 86-2 and from the dual corners of the bottom portion 86-3 toward a center of the bottom portion 86-3. Therefore, light emitting from LEDs 200a and 200b to input into the nonlinear light guide member or portion 76 with “U” shaped configuration can output the light with a substantially uniform luminance along an entire length of the light output side surface or side surface portions of the distributing light guide 76 and resultantly a lighting with substantially uniform surface luminance or brightness can be produced from substantially entire areas of the surface lighting surface 30a of the surface lighting light guide member or portion 30. In FIG. 75 and FIG. 76, the light guide unit 143 is composed of the surface lighting light guide 30, the “U” shaped channel light guide 86 and “U” shaped nonlinear distributing light guide 76, in which three light guides or light guide portions 30, 86 and 76 are connected one another in that order to form a single integrated composite unit. However, three light guides 30, 86 and 76 may be separated to be in contact with in that order to one another, or two light guides of the three light guides 30, 86 and 76 may form a composite, instead. Reference is made to FIG. 77 and FIG. 78 showing a twenty sixth embodiment of the present invention. FIG. 77 is a schematic exploded perspective view showing a surface illuminator of the twenty sixth embodiment and FIG. 78 is a schematic top view showing the surface illuminator in the FIG. 77. As shown in FIG. 77 and FIG. 78, a surface illuminator is briefly composed of a light guide unit 144 and two LEDs 200a and 200b, in which the surface illuminator of this embodiment is a modification of the twenty first embodiment as shown in FIG. 74 and FIG. 75. The light guide unit 144 is made of a light transmitting member having a substantially transparent material. The light guide unit 144 is composed of a surface lighting light guide member 30, a nonlinear light guide member or portion 75 and an optical channel light guide member or portion 89 disposed therebetween, in which the optical channel light guide member or portion 89 is sandwiched laterally by the nonlinear light guide member 75 and the surface lighting light guide member 30. The nonlinear light guide member 75 is composed of a substantially “U” shaped light guide member having a substantially linear first leg portion 75-1, a substantially linear second leg portion 75-2 that is opposed to and parallel with the first leg portion 75-1 and a substantially linear bottom portion 75-3 connected with a first slanted side surface 75i of the first leg portion 75-1 and a second slanted side surface 75h of the second leg portion 75-2. The first and second leg portions 75-1 and 75-2 have first and second end surfaces 75-1e and 75-2e that are optically opposed to each other via an entire length of “U” shaped light guide 75. The nonlinear light guide member 75 is acting as a distributing light guide for distributing light along an entire nonlinear length thereof, in which the light is introduced from the first and second end surfaces 75-1e and 75-2e where LEDs 200a and 200b are positioned so as to be in contact with or adjacent to the first and second end surfaces 75-1e and 75-2e. The channel light guide or optical channel light guide member 89 is composed of opposed linear first and second leg portions 89-1 and 89-2 and a bottom linear portion 89-3 connected with the linear first and second leg portions to form a substantially “U” shaped configuration as a whole similar to the configuration of the distributing light guide 75, in which an external contour with “U” shape of the channel light guide 89 is substantially equal in size to an internal contour with “U” shape of the distributing light guide 75 so as to be connected or in contact with to each other. An internal contour with “U” shape of the channel light guide 89 is substantially equal in size to an contour with “U” shape of three adjacent side surfaces 30c, 30e and 30f of the surface lighting light guide 30 so as to be connected or in contact with to each other. The channel light guide or optical channel light guide member 89 is further composed of a plurality of optical channel elements 90 and a plurality of interposers 91, in which the optical channel elements 90 and the adjacent interposers 91 are alternately aligned so as to form a substantially “U” shaped array as a whole, in such a manner that each of the optical channel elements 90 is positioned to be sandwiched by the adjacent interposers 91. The interposers 91 are composed of a light transmitting solid member having a substantially transparent material having a refractive index lower than the refractive index of the optical channel elements 91. The interposers 91 may substitute air for the light transmitting solid member since the refractive index (value=1) of the air is generally lower than that of the light transmitting solid member such as PMMA or PC. Each of the optical channel elements 90 has a substantially equal width and equal light input surface area, while each of the interposers 91 has a substantially variable width. The optical channel elements 90 are distributed variably in a pitch therebetween in a stepwise or continuous manner to form a first gradation pattern in such a manner that the quantity of the channel elements 90 increases from the dual end surfaces of the first and second leg portions 89-1 and 89-2 toward the dual corners of the bottom portion 89-3 of the channel light guide portion 89 and from the dual corners of the bottom portion 89-3 toward a center of the bottom portion 89-3. The interposers 91 are distributed variably in the width in a stepwise or continuous manner to form a second gradation pattern in such a manner that the width of the interposers 91 substantially decreases from the dual end surfaces of the first and second leg portions 89-1 and 89-2 toward the dual corners of the bottom portion 89-3 of the channel light guide portion 89 and from the dual corners of the bottom portion 89-3 toward a center of the bottom portion 89-3. Therefore, light emitting from LEDs 200a and 200b to input into the nonlinear light guide member or portion 75 with “U” shaped configuration can output the light with a substantially uniform luminance along an entire length of the light output side surface or side surface portions of the distributing light guide 75 and resultantly a lighting with substantially uniform surface luminance or brightness can be produced from substantially entire areas of the surface lighting surface 30a of the surface lighting light guide member or portion 30. In FIG. 77 and FIG. 78, the light guide unit 144 is composed of the surface lighting light guide 30, the “U” shaped channel light guide 89 and the “U” shaped nonlinear distributing light guide 75, in which three light guides or light guide portions 30, 89 and 75 are connected one another in that order to form a single integrated composite unit. However, three light guides 30, 89 and 75 may be separated to be in contact with in that order to one another, or two light guides of the three light guides 30, 89 and 75 may form a composite, instead. Reference is made to FIG. 79 and FIG. 80 showing a twenty seventh embodiment of the present invention. FIG. 79 is a schematic exploded perspective view showing a surface illuminator of the twenty seventh embodiment and FIG. 80 is a schematic top view showing the surface illuminator in the FIG. 79. As shown in FIG. 70 and FIG. 80, a surface illuminator is briefly composed of a light guide unit 145 and two LEDs 200a and 200b, in which the surface illuminator of this embodiment is a modification of the embodiment as shown in FIG. 77 and FIG. 78. The light guide unit 145 is made of a light transmitting member having a substantially transparent material. The light guide unit 145 is composed of a surface lighting light guide member 30, a nonlinear light guide member or portion 76 and an optical channel light guide member or portion 89 disposed therebetween, in which the optical channel light guide member or portion 89 is sandwiched laterally by the nonlinear light guide member 76 and the surface lighting light guide member 30. The nonlinear light guide member 76 is composed of a substantially “U” shaped light guide member having a substantially linear first leg portion 76-1, a substantially linear second leg portion 76-2 that is opposed to and parallel with the first leg portion 76-1 and a substantially linear bottom portion 76-3 connected with a first slanted side surface 76i of the first leg portion 76-1 and a second slanted side surface 76h of the second leg portion 76-2. The first and second leg portions 76-1 and 76-2 have first and second end surfaces 76-1e and 76-2e that are optically opposed to each other via an entire length of “U” shaped light guide 76. The nonlinear light guide member 76 is acting as a distributing light guide for distributing light along an entire nonlinear length thereof, in which the light is introduced from the first and second end surfaces 76-1e and 76-2e where LEDs 200a and 200b are positioned so as to be in contact with or adjacent to the first and second end surfaces 76-1e and 76-2e. It is noted that each of the first and second opposed light guides 76-1 and 76-2 and the bottom light guide 76-3 has a tapered configuration, in which the first and second opposed light guides 76-1 and 76-2 have tapered rear side surfaces and the bottom light guide 76-3 has a tapered rear side surface, in which the distance between the tapered rear side surfaces 76-1c and 76-2c and the non-tapered front side surfaces 76-1d and 76-2d decreases from the corner sides 76i and 76h toward the end surfaces 76-1e and 76-2e and the distance between the tapered rear side surface 76-3c and the front side surface 76-3d decreases from the corner sides 76l and 76h toward the center of the bottom light guide 76-3. On the contrary, in the twenty third embodiment as shown in FIG. 78 and FIG. 79, the distance between the rear and front side surfaces (75-1c and 75-1d) and (75-2c and 75-2d) of the first and second leg light guides 75-1 and 75-2 are substantially equal or uniform and the distance between the rear and front side surfaces 76-3c and 76-3d of the bottom light guide 76-3 is substantially equal or uniform. The channel light guide or optical channel light guide member 89 is composed of opposed linear first and second leg portions 89-1 and 89-2 and a bottom linear portion 89-3 connected with the linear first and second leg portions to form a substantially “U” shaped configuration as a whole similar to the configuration of the distributing light guide 76, in which an external contour with “U” shape of the channel light guide 89 is substantially equal in size to an internal contour with “U” shape of the distributing light guide 76 so as to be connected or in contact with to each other. An internal contour with “U” shape of the channel light guide 89 is substantially equal in size to an contour with “U” shape of three adjacent side surfaces 30c, 30e and 30f of the surface lighting light guide 30 so as to be connected or in contact with to each other. The channel light guide or optical channel light guide member 89 is further composed of a plurality of optical channel elements 90 and a plurality of interposers 91, in which the optical channel elements 90 and the adjacent interposers 91 are alternately aligned so as to form a substantially “U” shaped array as a whole, in such a manner that each of the optical channel elements 90 is positioned to be sandwiched by the adjacent interposers 91. The interposers 91 are composed of a light transmitting solid member having a substantially transparent material having a refractive index lower than the refractive index of the optical channel elements 91. The interposers 91 may substitute air for the light transmitting solid member since the refractive index (value=1) of the air is generally lower than that of the light transmitting solid member such as PMMA or PC. Each of the optical channel elements 90 has a substantially equal width and equal light input surface area, while each of the interposers 91 has a substantially variable width. The optical channel elements 90 are distributed variably in a pitch therebetween in a stepwise or continuous manner to form a first gradation pattern in such a manner that the quantity of the channel elements 90 increases from the dual end surfaces of the first and second leg portions 89-1 and 89-2 toward the dual corners of the bottom portion 89-3 of the channel light guide portion 89 and from the dual corners of the bottom portion 89-3 toward a center of the bottom portion 89-3. The interposers 91 are distributed variably in the width in a stepwise or continuous manner to form a second gradation pattern in such a manner that the width of the interposers 91 substantially decreases from the dual end surfaces of the first and second leg portions 89-1 and 89-2 toward the dual corners of the bottom portion 89-3 of the channel light guide portion 89 and from the dual corners of the bottom portion 89-3 toward a center of the bottom portion 89-3. Therefore, light emitting from LEDs 200a and 200b to input into the nonlinear light guide member or portion 76 with “U” shaped configuration can output the light with a substantially uniform luminance along an entire length of the light output side surface or side surface portions of the distributing light guide 76 and resultantly a lighting with substantially uniform surface luminance or brightness can be produced from substantially entire areas of the surface lighting surface 30a of the surface lighting light guide member or portion 30. In FIG. 79 and FIG. 80, the light guide unit 145 is composed of the surface lighting light guide 30, the “U” shaped channel light guide 89 and the “U” shaped nonlinear distributing light guide 76, in which three light guides or light guide portions 30, 89 and 76 are connected one another in that order to form a single integrated composite unit. However, three light guides 30, 89 and 76 may be separated to be in contact with in that order to one another, or two light guides of the three light guides 30, 89 and 76 may form a composite, instead. Reference is made to FIG. 81 and FIG. 82 showing a twenty eighth embodiment of the present invention. FIG. 81 is a schematic exploded perspective view showing a surface illuminator of the twenty eighth embodiment and FIG. 82 is a schematic top view showing the surface illuminator in the FIG. 81. As shown in FIG. 81 and FIG. 82, a surface illuminator is briefly composed of a light guide unit 145 and four LEDs 200a, 200b, 200c and 200d. The light guide unit 146 is made of a light transmitting member having a substantially transparent material. The light guide unit 146 is composed of a surface lighting light guide member 30, a nonlinear light guide member or portion 75 and an optical channel light guide member or portion 92 disposed therebetween, in which the optical channel light guide member or portion 92 is sandwiched laterally by the nonlinear light guide member 75 and the surface lighting light guide member 30. The nonlinear light guide member 75 is composed of a substantially “U” shaped light guide member having a substantially linear first leg portion 75-1, a substantially linear second leg portion 75-2 that is opposed to and parallel with the first leg portion 75-1 and a substantially linear bottom portion 75-3 connected with a first slanted side surface 75i of the first leg portion 75-1 and a second slanted side surface 75h of the second leg portion 75-2. The first and second leg portions 75-1 and 75-2 have first and second end surfaces 75-1e and 75-2e that are optically opposed to each other via an entire length of “U” shaped light guide 75. The nonlinear light guide member 75 is acting as a distributing light guide for distributing light along an entire nonlinear length thereof, in which the light is introduced from the first and second end surfaces 75-1e and 75-2e and dual corner inclined surfaces 75i and 75h, where the four LEDs 200a, 200b, 200c and 200d are positioned so as to be in contact with or adjacent to the first and second end surfaces 75-1e and 75-2e and the dual corner inclined surfaces 75i and 75h. The distance between the rear and front side surfaces (75-1c and 75-1d) and (75-2c and 75-2d) of the first and second leg light guides 75-1 and 75-2 are substantially equal or uniform and the distance between the rear and front side surfaces 75-3c and 75-3d of the bottom light guide 75-3 is substantially equal or uniform. THE channel light guide or optical channel light guide member 92 is composed of opposed linear first and second leg portions 92-1 and 92-2 and a bottom linear portion 92-3 connected with the linear first and second leg portions to form a substantially “U” shaped configuration as a whole similar to the configuration of the distributing light guide 75, in which an external contour with “U” shape of the channel light guide 92 is substantially equal in size to an internal contour with “U” shape of the distributing light guide 75 so as to be connected or in contact with to each other. An internal contour with “U” shape of the channel light guide 92 is substantially equal in size to an contour with “U” shape of three adjacent side surfaces 30c, 30e and 30f of the surface lighting light guide 30 so as to be connected or in contact with to each other. The channel light guide or optical channel light guide member 92 is further composed of a plurality of optical channel elements 93 and a plurality of interposers 94, in which the optical channel elements 93 and the adjacent interposers 94 are alternately aligned so as to form a substantially “U” shaped array as a whole, in such a manner that each of the optical channel elements 93 is positioned to be sandwiched by the adjacent interposers 94. The interposers 94 are composed of a light transmitting solid member having a substantially transparent material having a refractive index lower than the refractive index of the optical channel elements 94. The interposers 94 may substitute air for the light transmitting solid member since the refractive index (value=1) of the air is generally lower than that of the light transmitting solid member such as PMMA or PC. Each of the optical channel elements 93 has a substantially equal width and equal light input surface area, while each of the interposers 94 has a substantially variable width. The optical channel elements 93 are distributed variably in a pitch therebetween in a stepwise or continuous manner to form a first gradation pattern in such a manner that the quantity of the channel elements 93 increases from the dual end surfaces of the first and second leg portions 92-1 and 92-2 and the dual corners of the bottom portion 92-3 toward the centers of the first and second leg portions 92-1 and 92-2 and from the dual corners of the bottom portion 92-3 toward the center of the bottom portion 92-3. The interposers 94 are distributed variably in the width in a stepwise or continuous manner to form a second gradation pattern in such a manner that the width of the interposers 94 substantially decreases from the dual end surfaces of the first and second leg portions 92-1 and 92-2 and the dual corners of the bottom portion 92-3 toward the centers of the first and second leg portions 92-1 and 92-2 and from the dual corners of the bottom portion 92-3 toward the center of the bottom portion 92-3. Therefore, light emitting from the LEDs 200a, 200b, 200c and 200d to input into the nonlinear light guide member or portion 75 with “U” shaped configuration can output the light with a substantially uniform luminance along an entire length of the light output side surface or side surface portions 75-1d, 75-2d, and 75-3d of the distributing light guide 75 and resultantly a lighting with substantially uniform surface luminance or brightness can be produced from substantially entire areas of the surface lighting surface 30a of the surface lighting light guide member or portion 30. In FIG. 83, the light guide unit 146 is composed of the surface lighting light guide 30, the “U” shaped channel light guide 92 and the “U” shaped nonlinear distributing light guide 75, in which three light guides or light guide portions 30, 92 and 75 are connected one another in that order to form a single integrated composite unit. However, three light guides 30, 92 and 75 may be separated to be in contact with in that order to one another, or two light guides of the three light guides 30, 92 and 75 may form a composite, instead. Reference is made to FIG. 83 and FIG. 84 showing a twenty ninth embodiment of the present invention. FIG. 83 is a schematic exploded perspective view showing a surface illuminator of the twenty ninth embodiment and FIG. 84 is a schematic top view showing the surface illuminator in the FIG. 83. As shown in FIG. 83 and FIG. 84, a surface illuminator is briefly composed of a light guide unit 147 and four LEDs 200a, 200b, 200c and 200d, in which the surface illuminator of this embodiment is a modification of the embodiment as shown in FIG. 81 and FIG. 82. The light guide unit 147 is made of a light transmitting member having a substantially transparent material. The light guide unit 147 is composed of a surface lighting light guide member 30, a nonlinear light guide member or portion 76 and an optical channel light guide member or portion 92 disposed therebetween, in which the optical channel light guide member or portion 92 is sandwiched laterally by the nonlinear light guide member 76 and the surface lighting light guide member 30. The nonlinear light guide member 76 is composed of a substantially “U” shaped light guide member having a substantially linear first leg portion 76-1, a substantially linear second leg portion 76-2 that is opposed to and parallel with the first leg portion 76-1 and a substantially linear bottom portion 76-3 connected with a first slanted side surface 76i of the first leg portion 76-1 and a second slanted side surface 76h of the second leg portion 76-2. The first and second leg portions 76-1 and 76-2 have first and second end surfaces 76-1e and 76-2e that are optically opposed to each other via an entire length of “U” shaped light guide 76. The nonlinear light guide member 76 is acting as a distributing light guide for distributing light along an entire nonlinear length thereof, in which the light is introduced from the first and second end surfaces 76-1e and 76-2e and dual corner inclined surfaces 76i and 76h, where the four LEDs 200a, 200b, 200c and 200d are positioned so as to be in contact with or adjacent to the first and second end surfaces 76-1e and 76-2e and the dual corner inclined surfaces 76i and 76h. It is noted that each of the first and second opposed light guides 76-1 and 76-2 and the bottom light guide 76-3 has a tapered configuration, in which the first and second opposed light guides 76-1 and 76-2 have tapered rear side surfaces and the bottom light guide 76-3 has a tapered rear side surface, in which the distance between the tapered rear side surfaces 76-1c and 76-2c and the non-tapered front side surfaces 76-1d and 76-2d decreases from the corner sides 76i and 76h toward the end surfaces 76-1e and 76-2e and the distance between the tapered rear side surface 76-3c and the front side surface 76-3d decreases from the corner sides 76l and 76h toward the center of the bottom light guide 76-3. On the contrary, in the twenty fifth embodiment as shown in FIG. 82 and FIG. 83, the distance between the rear and front side surfaces (75-1c and 75-1d) and (75-2c and 75-2d) of the first and second leg light guides 75-1 and 75-2 are substantially equal or uniform and the distance between the rear and front side surfaces 76-3c and 76-3d of the bottom light guide 76-3 is substantially equal or uniform. The channel light guide or optical channel light guide member 92 is composed of opposed linear first and second leg portions 92-1 and 92-2 and a bottom linear portion 92-3 connected with the linear first and second leg portions to form a substantially “U” shaped configuration as a whole similar to the configuration of the distributing light guide 76, in which an external contour with “U” shape of the channel light guide 92 is substantially equal in size to an internal contour with “U” shape of the distributing light guide 76 so as to be connected or in contact with to each other. An internal contour with “U” shape of the channel light guide 92 is substantially equal in size to an contour with “U” shape of three adjacent side surfaces 30c, 30e and 30f of the surface lighting light guide 30 so as to be connected or in contact with to each other. The channel light guide or optical channel light guide member 92 is further composed of a plurality of optical channel elements 93 and a plurality of interposers 94, in which the optical channel elements 93 and the adjacent interposers 94 are alternately aligned so as to form a substantially “U” shaped array as a whole, in such a manner that each of the optical channel elements 93 is positioned to be sandwiched by the adjacent interposers 94. The interposers 94 are composed of a light transmitting solid member having a substantially transparent material having a refractive index lower than the refractive index of the optical channel elements 94. The interposers 94 may substitute air for the light transmitting solid member since the refractive index (value=1) of the air is generally lower than that of the light transmitting solid member such as PMMA or PC. Each of the optical channel elements 93 has a substantially equal width and equal light input surface area, while each of the interposers 94 has a substantially variable width. The optical channel elements 93 are distributed variably in a pitch therebetween in a stepwise or continuous manner to form a first gradation pattern in such a manner that the quantity of the channel elements 93 increases from the dual end surfaces of the first and second leg portions 92-1 and 92-2 and the dual corners of the bottom portion 92-3 toward the centers of the first and second leg portions 92-1 and 92-2 and from the dual corners of the bottom portion 92-3 toward the center of the bottom portion 92-3. The interposers 94 are distributed variably in the width in a stepwise or continuous manner to form a second gradation pattern in such a manner that the width of the interposers 94 substantially decreases from the dual end surfaces of the first and second leg portions 92-1 and 92-2 and the dual corners of the bottom portion 92-3 toward the centers of the first and second leg portions 92-1 and 92-2 and from the dual corners of the bottom portion 92-3 toward the center of the bottom portion 92-3. Therefore, light emitting from the LEDs 200a, 200b, 200c and 200d to input into the nonlinear light guide member or portion 76 with “U” shaped configuration can output the light with a substantially uniform luminance along an entire length of the light output side surface or side surface portions 76-1d, 76-2d, and 76-3d of the distributing light guide 76 and resultantly a lighting with substantially uniform surface luminance or brightness can be produced from substantially entire areas of the surface lighting surface 30a of the surface lighting light guide member or portion 30. In FIG. 83 and FIG. 84, the light guide unit 147 is composed of the surface lighting light guide 30, the “U” shaped channel light guide 92 and the “U” shaped nonlinear distributing light guide 76, in which three light guides or light guide portions 30, 92 and 76 are connected one another in that order to form a single integrated composite unit. However, three light guides 30, 92 and 76 may be separated to be in contact with in that order to one another, or two light guides of the three light guides 30, 92 and 76 may form a composite, instead. Reference is made to FIG. 85 and FIG. 86 showing a thirtieth embodiment of the present invention. FIG. 85 is a schematic exploded perspective view showing a surface illuminator of the thirtieth embodiment and FIG. 86 is a schematic top view showing the surface illuminator in the FIG. 85. As shown in FIG. 85 and FIG. 86, a surface illuminator is briefly composed of a light guide unit 148 and at least one LED 200, in which the surface illuminator of this embodiment is a modification of the embodiment as shown in FIG. 71 and FIG. 72. The light guide unit 148 is made of a light transmitting member having a substantially transparent material. The light guide unit 148 is composed of a surface lighting light guide member 30, a nonlinear light guide member or portion 77 and an optical channel light guide member or portion 95 disposed therebetween, in which the optical channel light guide member or portion 95 is sandwiched laterally by the nonlinear light guide member 77 and the surface lighting light guide member 30. The nonlinear light guide member 77 is acting as a distributing light guide for distributing light along an entire length thereof. The nonlinear light guide member 77 is composed of an annular light guide member having substantially rectangular flame, “O” shaped, flame-like, loop-like or ring-like light guide member, in which the nonlinear light guide member 77 is further composed of a substantially linear first portion 77-1, a substantially linear second portion 77-2 opposed to and parallel with the substantially linear first portion 77-1, a substantially linear third portion 77-3 and a substantially linear fourth portion 77-4 opposed to and parallel with the substantially linear first portion 77-3. The nonlinear light guide member 77 is further provided with four corner surfaces 77i, 77h, 77j and 77k at the four corners of four substantially linear first, second, third and fourth portions 77-1, 77-2, 77-3 and 77-4, where the first, second, third and fourth portions 77-1, 77-2, 77-3 and 77-4 are connected to one another. The first, second, third and fourth portions 77-1, 77-2, 77-3 and 77-4 have rear side surfaces 77-1c, 77-2c, 77-3c and 77-4c and front side surfaces 77-1d, 77-2d, 77-3d and 774d opposed to the rear side surfaces 77-1c, 77-2c, 77-3c and 77-4c respectively. The substantially linear third portion 77-3 is provided with a reflector 40 near a center thereof in the front side surface 77-3d, in which the reflector 40 is composed of opposed reflecting surfaces or portions 40a and 40b with a substantially “V” shaped configuration that is one portion of the front side surface 77-3d. LED 200 is disposed in contact with, adjacent to the rear side surface 77-3d near a center thereof in the substantially linear third portion 77-3 so that a light emitting window of the LED 200 faces the opposed reflecting surfaces 40a and 40b of the reflector 40. The channel light guide or optical channel light guide member 95 is composed of an annular light guide member having a substantially rectangular flame, “O” shaped, flame-like, loop-like or ring-like light guide member, in which the optical channel light guide member 95 is further composed of a substantially linear first portion 95-1, a substantially linear second portion 95-2 opposed to and parallel with the substantially linear first portion 95-1, a substantially linear third portion 95-3 and a substantially linear fourth portion 95-4 opposed to and parallel with the substantially linear first portion 95-1. The first, second, third and fourth portions 95-1, 95-2, 95-3 and 95-4 of the channel light guide or optical channel light guide member 95 are connected together to form the substantially flame-like configuration as a whole similar to the configuration of the distributing light guide 77, in which an external contour with the substantially rectangular flame-like configuration of the channel light guide 95 is substantially equal in size to an internal contour with the substantially rectangular flame-like configuration of the distributing light guide 77 so as to be connected or in contact with to each other. An internal contour with the substantially rectangular flame-like configuration of the channel light guide 95 is substantially equal in size to an contour with the substantially rectangular shape of four side surfaces 30c, 30d, 30e and 30f of the surface lighting light guide 30 so as to be connected or in contact with to each other. The channel light guide or optical channel light guide member 95 is further composed of a plurality of optical channel elements 97 and a plurality of interposers 98, in which the optical channel elements 97 and the adjacent interposers 98 are alternately aligned so as to form a substantially rectangular flame-like array as a whole, in such a manner that each of the optical channel elements 97 is positioned to be sandwiched by the adjacent interposers 98. The interposers 98 are composed of a light transmitting solid member having a substantially transparent material having a refractive index lower than the refractive index of the optical channel elements 97. The interposers 98 may substitute air for the light transmitting solid member since the refractive index (value=1) of the air is generally lower than that of the light transmitting solid member such as PMMA or PC. Each of the optical channel elements 97 has a substantially equal width and equal light input surface area, while each of the interposers 98 has a substantially variable width. The optical channel elements 97 are distributed variably in a pitch therebetween in a stepwise or continuous manner to form a gradation pattern in such a manner that the quantity of the channel elements 97 increases from a center of the third distributing light guide portion 77-3 where LED 200 is positioned toward a center of the fourth distributing light guide portion 77-4 via the first and second distributing light guide portions 77-1 and 77-2. On the contrary, the interposers 98 are distributed variably in the width in a stepwise or continuous manner to form a gradation pattern in such a manner that the width of the interposers 98 decreases from a center of the third distributing light guide portion 77-3 where LED 200 is positioned toward a center of the fourth distributing light guide portion 77-4 via the first and second distributing light guide portions 77-1 and 77-2. Therefore, light emitting from LED 200 to input into the nonlinear light guide member or portion 77 with the substantially rectangular flame-like shaped configuration can output the light with a substantially uniform luminance along an entire length of the light output side surface or side surface portion 77-1d, 77-2d, 77-3d and 77-4d and resultantly a lighting with substantially uniform surface luminance or brightness can be produced from substantially entire areas of the surface lighting surface 30a of the surface lighting light guide member or portion 30. In FIG. 85 and FIG. 86, the light guide unit 148 is composed of the surface lighting light guide 30, the substantially rectangular flame-like shaped channel light guide 95 and the substantially rectangular flame-like shaped nonlinear distributing light guide 77, in which three light guides 30, 95 and 77 are connected one another in that order to form a single integrated composite unit. However, three light guides 30, 95 and 77 may be separated to be in contact with in that order to one another, or two light guides of the three light guides 30, 95 and 77 may form a composite, instead. Reference is made to FIG. 87 and FIG. 88 showing a thirty first embodiment of the present invention. FIG. 87 is a schematic exploded perspective view showing a surface illuminator of the thirty first embodiment and FIG. 88 is a schematic top view showing the surface illuminator in the FIG. 87. As shown in FIG. 87 and FIG. 88, a surface illuminator is briefly composed of a light guide unit 149 and at least one LED 200, in which the surface illuminator of this embodiment is a modification of the embodiment as shown in FIG. 85 and FIG. 86. The light guide unit 149 is made of a light transmitting member having a substantially transparent material. The light guide unit 149 is composed of a surface lighting light guide member 30, a nonlinear light guide member or portion 78 and an optical channel light guide member or portion 95 disposed therebetween, in which the optical channel light guide member or portion 95 is sandwiched laterally by the nonlinear light guide member 78 and the surface lighting light guide member 30. The nonlinear light guide member or distributing light guide member 78 is acting as a distributing light guide for distributing light along an entire length thereof. The nonlinear light guide member 78 is composed of an annular light guide member having a substantially rectangular flame, “O” shaped, flame-like, loop-like or ring-like light guide member, in which the nonlinear light guide member 78 is further composed of a substantially linear first portion 78-1, a substantially linear second portion 78-2 opposed to and parallel with the substantially linear first portion 78-1, a substantially linear third portion 78-3 and a substantially linear fourth portion 78-4 opposed to and parallel with the substantially linear first portion 78-3. The nonlinear light guide member 78 is further provided with four corner and corner surfaces 78i, 78h, 78j and 78k at the four corners of four substantially linear first, second, third and fourth portions 78-1, 78-2, 78-3 and 78-4, where the first, second, third and fourth distributing light guide portions 78-1, 78-2, 78-3 and 78-4 are connected to one another. The first, second, third and fourth portions 78-1, 78-2, 78-3 and 78-4 have rear side surfaces 78-1c, 78-2c, 78-3c and 78-4c and front side surfaces 78-1d, 78-2d, 78-3d and 78-4d opposed to the rear side surfaces 78-1c, 78-2c, 78-3c and 78-4c respectively. It is noted that each of the first, second, third and fourth distributing light guide portions 78-1, 78-2, 78-3 and 78-4 has a tapered configuration, in which the distributing light guide portions 78-1, 78-2, 78-3 and 78-4 have tapered rear side surfaces 78-1c, 78-2c, 78-3c and 78-4c, in which the distance between the tapered rear side surfaces 78-1c and 78-2c and the non-tapered front side surfaces 78-1d and 78-2d decreases from the corners 78i and 78h toward the corner surfaces 78j and 78k and the distance between the tapered rear side surface 78-3c and 78-4c and the front side surface 78-3d and 78-4d decreases from the centers of the third and fourth distributing light guide 78-3 and 78-4 toward the corner surfaces 78j and 78k. On the contrary, in the twenty sixth embodiment as shown in FIG. 86 and FIG. 87, the distance between the rear and front side surfaces (78-1c, 78-2c, 78-3c and 78-4c) and (78-1d, 78-2d, 78-3d and 78-4d) are substantially equal or uniform. The substantially linear third portion 78-3 is provided with a reflector 40 near a center thereof in the front side surface 78-3d, in which the reflector 40 is composed of opposed reflecting surfaces or portions 40a and 40b with a substantially “V” shaped configuration that is one portion of the front side surface 78-3d. LED 200 is disposed in contact with, adjacent to the rear side surface 78-3d near a center thereof in the substantially linear third portion 78-3 so that a light emitting window of the LED 200 faces the opposed reflecting surfaces 40a and 40b of the reflector 40. The channel light guide or optical channel light guide member 95 is composed of an annular light guide member having a substantially rectangular flame, “O” shaped, flame-like, loop-like or ring-like light guide member, in which the optical channel light guide member 95 is further composed of a substantially linear first portion 95-1, a substantially linear second portion 95-2 opposed to and parallel with the substantially linear first portion 95-1, a substantially linear third portion 95-3 and a substantially linear fourth portion 95-4 opposed to and parallel with the substantially linear first portion 95-1. The first, second, third and fourth portions 95-1, 95-2, 95-3 and 95-4 of the channel light guide or optical channel light guide member 95 are connected together to form the substantially flame-like configuration as a whole similar to the configuration of the distributing light guide 78, in which an external contour with the substantially rectangular flame-like configuration of the channel light guide 95 is substantially equal in size to an internal contour with the substantially rectangular flame-like configuration of the distributing light guide 78 so as to be connected or in contact with to each other. An internal contour with the substantially rectangular flame-like configuration of the channel light guide 95 is substantially equal in size to an contour with the substantially rectangular shape of four side surfaces 30c, 30d, 30e and 30f of the surface lighting light guide 30 so as to be connected or in contact with to each other. The channel light guide or optical channel light guide member 95 is further composed of a plurality of optical channel elements 97 and a plurality of interposers 98, in which the optical channel elements 97 and the adjacent interposers 98 are alternately aligned so as to form a substantially rectangular flame-like array as a whole, in such a manner that each of the optical channel elements 97 is positioned to be sandwiched by the adjacent interposers 98. The interposers 98 are composed of a light transmitting solid member having a substantially transparent material having a refractive index lower than the refractive index of the optical channel elements 97. The interposers 98 may substitute air for the light transmitting solid member since the refractive index (value=1) of the air is generally lower than that of the light transmitting solid member such as PMMA or PC. Each of the optical channel elements 97 has a substantially equal width and equal light input surface area, while each of the interposers 98 has a substantially variable width. The optical channel elements 97 are distributed variably in a pitch therebetween in a stepwise or continuous manner to form a gradation pattern in such a manner that the quantity of the channel elements 97 increases from a center of the third distributing light guide portion 78-3 where LED 200 is positioned toward a center of the fourth distributing light guide portion 78-4 via the first and second distributing light guide portions 78-1 and 78-2. On the contrary, the interposers 98 are distributed variably in the width in a stepwise or continuous manner to form a gradation pattern in such a manner that the width of the interposers 98 decreases from a center of the third distributing light guide portion 78-3 where LED 200 is positioned toward a center of the fourth distributing light guide portion 78-4 via the first and second distributing light guide portions 78-1 and 78-2. Therefore, light emitting from LED 200 to input into the nonlinear light guide member or portion 78 with the substantially rectangular flame-like shaped configuration can output the light with a substantially uniform luminance along an entire length of the light output side surface or side surface portion 78-1d, 78-2d, 78-3d and 784d and resultantly a lighting with substantially uniform surface luminance or brightness can be produced from substantially entire areas of the surface lighting surface 30a of the surface lighting light guide member or portion 30. In FIG. 87 and FIG. 88, the light guide unit 149 is composed of the surface lighting light guide 30, the substantially rectangular flame-like shaped channel light guide 95 and the substantially rectangular flame-like shaped nonlinear distributing light guide 78, in which three light guides 30, 95 and 78 are connected one another in that order to form a single integrated composite unit. However, three light guides 30, 95 and 78 may be separated to be in contact with in that order to one another, or two light guides of the three light guides 30, 95 and 78 may form a composite, instead. Reference is made to FIG. 89 and FIG. 90 showing a thirty second embodiment of the present invention, in which FIG. 89 is a schematic exploded perspective view showing a surface illuminator of the thirty second embodiment and FIG. 90 is a schematic top view showing the surface illuminator in the FIG. 89. As shown in FIG. 89 and FIG. 90, a surface illuminator is briefly composed of a light guide unit 150 and dual LEDs 200a and 200b, in which the surface illuminator of this embodiment is a modification of the embodiment as shown in FIG. 87 and FIG. 88. The light guide unit 150 is made of a light transmitting member having a substantially transparent material. The light guide unit 150 is composed of a surface lighting light guide member 30, a nonlinear light guide member or portion 78 and an optical channel light guide member or portion 95 disposed therebetween, in which the optical channel light guide member or portion 95′ is sandwiched laterally by the nonlinear light guide member 78 and the surface lighting light guide member 30. The nonlinear light guide member 78 is acting as a distributing light guide for distributing light along an entire length thereof. The nonlinear light guide member 78 is composed of an annular light guide member having a substantially rectangular flame-like, “O” shaped, flame-like or ring-like light guide member, in which the nonlinear light guide member 78 is further composed of a substantially linear first portion 78-1, a substantially linear second portion 78-2 opposed to and parallel with the substantially linear first portion 78-1, a substantially linear third portion 78-3 and a substantially linear fourth portion 78-4 opposed to and parallel with the substantially linear first portion 78-3. The nonlinear light guide member 78 is further provided with four corner surfaces 78i, 78h, 78j and 78k at the four corners of four substantially linear first, second, third and fourth portions 78-1, 78-2, 78-3 and 78-4, where the first, second, third and fourth portions 78-1, 78-2, 78-3 and 78-4 are connected to one another. The first, second, third and fourth portions 78-1, 78-2, 78-3 and 78-4 have rear side surfaces 78-1c, 78-2c, 78-3c and 78-4c and front side surfaces 78-1d, 78-2d, 78-3d and 78-4d opposed to the rear side surfaces 78-1c, 78-2c, 78-3c and 78-4c respectively. The substantially linear third and fourth distributing light guide portions 78-3 and 78-4 are provided with reflectors 40 and 40′ near each center thereof in the front side surface 78-3d and 78-4d, in which each of the reflectors 40 and 40′ is composed of opposed reflecting surfaces or portions (40a and 40b) or (40′a and 40′b) with a substantially “V” shaped configuration that is one portion of the front side surface 78-3d or 78-4d. LEDs 200a and 200b are disposed in contact with, adjacent to the rear side surface 78-3c and 78-4d near the centers thereof in the substantially linear third and fourth distributing light guide portions 78-3 and 78-4 so that each light emitting window of the LEDs 200a and 200b faces the opposed reflecting surfaces (40a and 40b of the reflector 40) or (40′a and 40′b of the reflector 40′). The channel light guide or optical channel light guide member 95′ is composed of an annular channel light guide member having a substantially rectangular flame-like channel light guide member, “O” shaped, flame-like, loop-like or ring-like light guide member, in which the optical channel light guide member 95′ is further composed of a substantially linear first portion 95′-1, a substantially linear second portion 95′-2 opposed to and parallel with the substantially linear first portion 95′-1, a substantially linear third portion 95′-3 and a substantially linear fourth portion 95′4 opposed to and parallel with the substantially linear first portion 95′-1. The first, second, third and fourth portions 95′-1, 95′-2, 95′-3 and 95′-4 of the channel light guide or optical channel light guide member 95′ are connected together to form the substantially flame-like configuration as a whole similar to the configuration of the distributing light guide 78, in which an external contour with the substantially rectangular flame-like configuration of the channel light guide 95′ is substantially equal in size to an internal contour with the substantially rectangular flame-like configuration of the distributing light guide 78 so as to be connected or in contact with to each other. An internal contour with the substantially rectangular flame-like configuration of the channel light guide 95′ is substantially equal in size to an contour with the substantially rectangular shape of four side surfaces 30c, 30d, 30e and 30f of the surface lighting light guide 30 so as to be connected or in contact with to each other. The channel light guide or optical channel light guide member 95′ is further composed of a plurality of optical channel elements 97′ and a plurality of interposers 98′, in which the optical channel elements 97′ and the adjacent interposers 98′ are alternately aligned so as to form a substantially rectangular flame-like array as a whole, in such a manner that each of the optical channel elements 97′ is positioned to be sandwiched by the adjacent interposers 98′. The interposers 98′ are composed of a light transmitting solid member having a substantially transparent material having a refractive index lower than the refractive index of the optical channel elements 97′. The interposers 98′ may substitute air for the light transmitting solid member since the refractive index (value=1) of the air is generally lower than that of the light transmitting solid member such as PMMA or PC. Each of the optical channel elements 97′ has a substantially equal width and equal light input surface area, while each of the interposers 98′ has a substantially variable width. The optical channel elements 97′ are distributed variably in a pitch or width therebetween in a stepwise or continuous manner to form a first gradation pattern in such a manner that the quantity or width of the channel elements 97′ increases from the centers of the third and fourth channel light guide portions 95′-3 and 95′-4 toward the centers of the first and second channel light guide portions 95′-3 and 95′4. On the contrary, the interposers 98′ are distributed variably in a width or pitch in a stepwise or continuous manner to form a second gradation pattern in such a manner that the width of the interposers 98′ decreases from the centers of the third and fourth channel light guide portions 95′-3 and 95′-4 toward the centers of the first and second channel light guide portions 95′-3 and 95′4. Therefore, light emitting from the dual LEDs 200a and 200b to input into the nonlinear i.e. annular light guide member or portion 78 with the substantially rectangular flame-like configuration can output the light with a substantially uniform luminance along an entire length of the light output side surface or side surface portion 78-1d, 78-2d, 78-3d and 784d and resultantly a lighting with substantially uniform surface luminance or brightness can be produced from substantially entire areas of the surface lighting surface 30a of the surface lighting light guide member or portion 30. In FIG. 89 and FIG. 90, the light guide unit 150 is composed of the surface lighting light guide 30, the substantially rectangular flame-like channel light guide member 95′ and the substantially rectangular flame-like distributing light guide 78, in which three light guides 30, 95′ and 78 are connected one another in that order to form a single integrated composite unit. However, three light guides 30, 95′ and 78 may be separated to be in contact with in that order to one another, or two light guides of the three light guides 30, 95′ and 78 may form a composite, instead. Reference is made to FIG. 91 and FIG. 92 showing a thirty third embodiment of the present invention, in which FIG. 91 is a schematic exploded perspective view showing a surface illuminator of the thirty third embodiment and FIG. 92 is a schematic top view showing the surface illuminator in the FIG. 91. As shown in FIG. 91 and FIG. 92, a surface illuminator is briefly composed of a light guide unit 151 and dual LEDs 200a and 200b. The light guide unit 151 is made of a light transmitting member having a substantially transparent material. The light guide unit 151 is composed of a surface lighting light guide member 30, a nonlinear light guide member or portion 79 and an optical channel light guide member or portion 95 disposed therebetween, in which the optical channel light guide member or portion 95′ is sandwiched laterally by the nonlinear light guide member 79 and the surface lighting light guide member 30. The nonlinear light guide member 79 is acting as a distributing light guide for distributing light along an entire length thereof. The nonlinear light guide member 79 is composed of an annular light guide member having a substantially rectangular flame-like, “O” shaped, flame-like or ring-like light guide member, in which the nonlinear light guide member 79 is further composed of a substantially linear first portion 79-1, a substantially linear second portion 79-2 opposed to and parallel with the substantially linear first portion 79-1, a substantially linear third portion 79-3 and a substantially linear fourth portion 79-4 opposed to and parallel with the substantially linear first portion 79-3. The nonlinear light guide member 79 is further provided with four corner surfaces 79i, 79h, 79j and 79k at the four corners of four substantially linear first, second, third and fourth portions 79-1, 79-2, 79-3 and 79-4, where the first, second, third and fourth portions 79-1, 79-2, 79-3 and 79-4 are connected to one another. The first, second, third and fourth portions 79-1, 79-2, 79-3 and 79-4 have rear side surfaces 79-1c, 79-2c, 79-3c and 79-4c and front side surfaces 78-1d, 79-2d, 79-3d and 79-4d opposed to the rear side surfaces 79-1c, 79-2c, 79-3c and 794c respectively. The substantially linear third and fourth distributing light guide portions 79-3 and 79-4 are provided with reflectors 40 and 40′ near each center thereof in the front side surface 79-3d and 794d, in which each of the reflectors 40 and 40′ is composed of opposed reflecting surfaces or portions (40a and 40b) or (40′a and 40′b) with a substantially “V” shaped configuration that is one portion of the front side surface 79-3d or 79-4d. It is noted that each of the first, second, third and fourth distributing light guide portions 79-1, 79-2, 79-3 and 79-4 has a tapered configuration, in which the distributing light guide portions 79-1, 79-2, 79-3 and 79-4 have tapered rear side surfaces 79-1c, 79-2c, 79-3c and 794c, in which the distance between the tapered rear side surfaces 79-1c and 79-2c and the non-tapered front side surfaces 79-1d and 79-2d decreases from the corner surfaces 79h, 79i, 79j and 79k toward the centers of the first and second distributing light guide portions 79-1 and 79-2 and the distance between the tapered rear side surface 79-3c and 794c and the front side surface 79-3d and 794d decreases from the centers of the third and fourth distributing light guide 79-3 and 79-4 toward the corner surfaces (79h and 79i) and (79j and 79k). On the contrary, in the twenty seventh embodiment as shown in FIG. 90 and FIG. 91, the distance between the rear and front side surfaces (78-1c, 78-2c, 78-3c and 78-4c) and (78-1d, 78-2d, 78-3d and 78-4d) are substantially equal or uniform. LEDs 200a and 200b are disposed in contact with, adjacent to the rear side surface 79-3c and 79-4d near the centers thereof in the substantially linear third and fourth distributing light guide portions 79-3 and 79-4 so that each light emitting window of the LEDs 200a and 200b faces the opposed reflecting surfaces (40a and 40b of the reflector 40) or (40′a and 40′b of the reflector 40′). The channel light guide or optical channel light guide member 95′ is composed of an annular channel light guide member having a substantially rectangular flame-like channel light guide member, “O” shaped, flame-like, loop-like or ring-like light guide member, in which the optical channel light guide member 95′ is further composed of a substantially linear first portion 95′-1, a substantially linear second portion 95′-2 opposed to and parallel with the substantially linear first portion 95′-1, a substantially linear third portion 95′-3 and a substantially linear fourth portion 95′-4 opposed to and parallel with the substantially linear first portion 95′-1. The first, second, third and fourth portions 95′-1, 95′-2, 95′-3 and 95′-4 of the channel light guide or optical channel light guide member 95′ are connected together to form the substantially flame-like configuration as a whole similar to the configuration of the distributing light guide 79, in which an external contour with the substantially rectangular flame-like configuration of the channel light guide 95′ is substantially equal in size to an internal contour with the substantially rectangular flame-like configuration of the distributing light guide 79 so as to be connected or in contact with to each other. An internal contour with the substantially rectangular flame-like configuration of the channel light guide 95′ is substantially equal in size to an contour with the substantially rectangular shape of four side surfaces 30c, 30d, 30e and 30f of the surface lighting light guide 30 so as to be connected or in contact with to each other. The channel light guide or optical channel light guide member 95′ is further composed of a plurality of optical channel elements 97′ and a plurality of interposers 98′, in which the optical channel elements 97′ and the adjacent interposers 98′ are alternately aligned so as to form a substantially rectangular flame-like array as a whole, in such a manner that each of the optical channel elements 97′ is positioned to be sandwiched by the adjacent interposers 98′. The interposers 98′ are composed of a light transmitting solid member having a substantially transparent material having a refractive index lower than the refractive index of the optical channel elements 97′. The interposers 98′ may substitute air for the light transmitting solid member since the refractive index (value=1) of the air is generally lower than that of the light transmitting solid member such as PMMA or PC. Each of the optical channel elements 97′ has a substantially equal width and equal light input surface area, while each of the interposers 98′ has a substantially variable width. The optical channel elements 97′ are distributed variably in a pitch or width therebetween in a stepwise or continuous manner to form a first gradation pattern in such a manner that the quantity or width of the channel elements 97′ increases from the centers of the third and fourth channel light guide portions 95′-3 and 95′-4 toward the centers of the first and second channel light guide portions 95′-3 and 95′4. On the contrary, the interposers 98′ are distributed variably in a width or pitch in a stepwise or continuous manner to form a second gradation pattern in such a manner that the width of the interposers 98′ decreases from the centers of the third and fourth channel light guide portions 95′-3 and 95′-4 toward the centers of the first and second channel light guide portions 95′-3 and 95′4. Therefore, light emitting from the dual LEDs 200a and 200b to input into the nonlinear i.e. annular light guide member or portion 79 with the substantially rectangular flame-like configuration can output the light with a substantially uniform luminance along an entire length of the light output side surface or side surface portion 79-1d, 79-2d, 79-3d and 79-4d and resultantly a lighting with substantially uniform surface luminance or brightness can be produced from substantially entire areas of the surface lighting surface 30a of the surface lighting light guide member or portion 30. In FIG. 91 and FIG. 92, the light guide unit 151 is composed of the surface lighting light guide 30, the substantially rectangular flame-like channel light guide member 95′ and the substantially rectangular flame-like distributing light guide 79, in which three light guides 30, 95′ and 79 are connected one another in that order to form a single integrated composite unit. However, three light guides 30, 95′ and 79 may be separated to be in contact with in that order to one another, or two light guides of the three light guides 30, 95′ and 79 may form a composite, instead. Reference is made to FIG. 93 and FIG. 94 showing a thirty fourth embodiment of the present invention, in which FIG. 93 is a schematic exploded perspective view showing a surface illuminator of the thirty fourth embodiment and FIG. 94 is a schematic top view showing the surface illuminator in the FIG. 93. As shown in FIG. 93 and FIG. 94, a surface illuminator is briefly composed of a light guide unit 152 and four LEDs 200a, 200b, 200c and 200d. The light guide unit 152 is made of a light transmitting member having a substantially transparent material. The light guide unit 152 is composed of a surface lighting light guide member 30, a nonlinear light guide member or portion 55 and an optical channel light guide member or portion 92a disposed therebetween, in which the optical channel light guide member or portion 92a is sandwiched laterally by the nonlinear light guide member 55 and the surface lighting light guide member 30. The nonlinear light guide member 55 is acting as a distributing light guide for distributing light along an entire length thereof. The nonlinear light guide member 55 is composed of an annular light guide member having a substantially rectangular flame-like, “O” shaped, flame-like or ring-like light guide member, in which the nonlinear light guide member 55 is further composed of a substantially linear first portion 55-1, a substantially linear second portion 55-2 opposed to and parallel with the substantially linear first portion 55-1, a substantially linear third portion 55-3 and a substantially linear fourth portion 55-4 opposed to and parallel with the substantially linear first portion 55-3. The nonlinear light guide member 55 is further provided with four corner surfaces 55i, 55h, 55j and 55k at the four corners of four substantially linear first, second, third and fourth portions 55-1, 55-2, 55-3 and 55-4, where the first, second, third and fourth portions 55-1, 55-2, 55-3 and 55-4 are connected to one another. The first, second, third and fourth distributing light guide portions 55-1, 55-2, 55-3 and 55-4 have rear side surfaces 55-1c, 55-2c, 55-3c and 55-4c and front side surfaces 55-1d, 55-2d, 55-3d and 55-4d opposed to the rear side surfaces 55-1c, 55-2c, 55-3c and 55-4c respectively. The four numbers or sets of LEDs 200a, 200b, 200c and 200d are disposed in contact with, adjacent to the four corner side surface 55h, 55i, 55j and 55k of the substantially linear first, second, third and fourth distributing light guide portions 55-1, 55-2, 55-3 and 55-4. The channel light guide or optical channel light guide member 92a is composed of an annular channel light guide member having a substantially rectangular flame-like channel light guide member, “O” shaped, flame-like, loop-like or ring-like light guide member, in which the optical channel light guide member 92a is further composed of a substantially linear first portion 92a-1, a substantially linear second portion 92a-2 opposed to and parallel with the substantially linear first portion 92a-1, a substantially linear third portion 92a-3 and a substantially linear fourth portion 92a-4 opposed to and parallel with the substantially linear first portion 92a-1. The first, second, third and fourth portions 92a-1, 92a-2, 92a-3 and 92a-4 of the channel light guide or optical channel light guide member 92a are connected together to form the substantially rectangular flame-like configuration as a whole similar to the configuration of the distributing light guide 55, in which an external contour with the substantially rectangular flame-like configuration of the channel light guide 92a is substantially equal in size to an internal contour with the substantially rectangular flame-like configuration of the distributing light guide 55 so as to be connected or in contact with to each other. An internal contour with the substantially rectangular flame-like configuration of the channel light guide 92a is substantially equal in size to an contour with the substantially rectangular shape of four side surfaces 30c, 30d, 30e and 30f of the surface lighting light guide 30 so as to be connected or in contact with to each other. The channel light guide or optical channel light guide member 92a is further composed of a plurality of optical channel elements 93a and a plurality of interposers 94a, in which the optical channel elements 93a and the adjacent interposers 94a are alternately aligned so as to form a substantially rectangular flame-like array as a whole, in such a manner that each of the optical channel elements 93a is positioned to be sandwiched by the adjacent interposers 94a. The interposers 94a are composed of a light transmitting solid member having a substantially transparent material having a refractive index lower than the refractive index of the optical channel elements 93a. The interposers 94a may substitute air for the light transmitting solid member since the refractive index (value=1) of the air is generally lower than that of the light transmitting solid member such as PMMA or PC. Each of the optical channel elements 93a has a substantially equal width and equal light input surface area, while each of the interposers 94a has a substantially variable width. The optical channel elements 93a are distributed variably in a pitch therebetween in a stepwise or continuous manner to form a first gradation pattern in such a manner that the quantity of the channel elements 93a increases from the four corners of the channel light guide portions 92a-1, 92a-2, 92a-3 and 92a-4 toward the four centers of the channel light guide portions 92a-1, 92a-2, 92a-3 and 92a-4. On the contrary, the interposers 94a are distributed variably in a width in a stepwise or continuous manner to form a second gradation pattern in such a manner that the width of the interposers 94a decreases from the four corners of the channel light guide portions 92a-1, 92a-2, 92a-3 and 92a-4 toward the four centers of the channel light guide portions 92a-1, 92a-2, 92a-3 and 92a-4. Therefore, light emitting from the LEDs 200a, 200b, 200c and 200d to input into the nonlinear i.e. annular distributing light guide member or portion 55 with the substantially rectangular flame-like configuration can output the light with a substantially uniform luminance along an entire length of the light output side surface or side surface portion 55-1d, 55-2d, 55-3d and 55-4d and resultantly a lighting with substantially uniform surface luminance or brightness can be produced from substantially entire areas of the surface lighting surface 30a of the surface lighting light guide member or portion 30. In FIG. 93 and FIG. 94, the light guide unit 152 is composed of the surface lighting light guide 30, the substantially rectangular flame-like channel light guide member 92a and the substantially rectangular flame-like distributing light guide 55, in which three light guides 30, 92a and 55 are connected one another in that order to form a single integrated composite unit. However, three light guides 30, 92a and 55 may be separated to be in contact with in that order to one another, or two light guides of the three light guides 30, 92a and 55 may form a composite, instead. Reference is made to FIG. 95 and FIG. 96 showing a thirty fifth embodiment of the present invention, in which FIG. 95 is a schematic exploded perspective view showing a surface illuminator of the thirty fifth embodiment and FIG. 96 is a schematic top view showing the surface illuminator in the FIG. 95, in which this embodiment is a modification of the embodiment as shown in FIG. 93 and FIG. 94. As shown in FIG. 95 and FIG. 96, a surface illuminator is briefly composed of a light guide unit 153 and four LEDs 200a, 200b, 200c and 200d. The light guide unit 153 is made of a light transmitting member having a substantially transparent material. The light guide unit 153 is composed of a surface lighting light guide member 30, a nonlinear light guide member or portion 56 and an optical channel light guide member or portion 92a disposed therebetween, in which the optical channel light guide member or portion 92a is sandwiched laterally by the nonlinear light guide member 56 and the surface lighting light guide member 30. The nonlinear light guide member 56 is acting as a distributing light guide for distributing light along an entire length thereof. The nonlinear light guide member 56 is composed of an annular light guide member having a substantially rectangular flame-like, “O” shaped, flame-like or ring-like light guide member, in which the nonlinear light guide member 56 is further composed of a substantially linear first portion 56-1, a substantially linear second portion 56-2 opposed to and parallel with the substantially linear first portion 56-1, a substantially linear third portion 56-3 and a substantially linear fourth portion 56-4 opposed to and parallel with the substantially linear first portion 56-3. The nonlinear light guide member 56 is further provided with four corner surfaces 56i, 56h, 56j and 56k at the four corners of four substantially linear first, second, third and fourth portions 56-1, 56-2, 56-3 and 56-4, where the first, second, third and fourth portions 56-1, 56-2, 56-3 and 56-4 are connected to one another. The first, second, third and fourth distributing light guide portions 56-1, 56-2, 56-3 and 56-4 have rear side surfaces 56-1c, 56-2c, 56-3c and 56-4c and front side surfaces 56-1d, 56-2d, 56-3d and 564d opposed to the rear side surfaces 56-1c, 56-2c, 56-3c and 56-4c respectively. The four numbers or sets of LEDs 200a, 200b, 200c and 200d are disposed in contact with, adjacent to the four corner side surfaces 56h, 56i, 56j and 56k of the substantially linear first, second, third and fourth distributing light guide portions 56-1, 56-2, 56-3 and 56-4. It is noted that each of the first, second, third and fourth distributing light guide portions 56-1, 56-2, 56-3 and 56-4 has a tapered configuration, in which the distributing light guide portions 56-1, 56-2, 56-3 and 56-4 have tapered rear side surfaces 56-1c, 56-2c, 56-3c and 56-4c, in which the distance between the tapered rear side surfaces 56-1c, 56-2c, 56-3c and 56-4c and the non-tapered side surfaces 56-1d, 56-2d, 56-3d and 56-4d decreases from the corner surfaces 56h, 56i, 56j and 56k toward the centers of the distributing light guide portions 56-1, 56-2, 56-3 and 56-4. On the contrary, in the thirtieth embodiment as shown in FIG. 94 and FIG. 95, the distance between the rear and front side surfaces (56-1c, 56-2c, 56-3c and 564c) and (56-1d, 56-2d, 56-3d and 564d) are substantially equal or uniform. The channel light guide or optical channel light guide member 92a is composed of an annular channel light guide member having a substantially rectangular flame-like channel light guide member, “O” shaped, flame-like, loop-like or ring-like light guide member, in which the optical channel light guide member 92a is further composed of a substantially linear first portion 92a-1, a substantially linear second portion 92a-2 opposed to and parallel with the substantially linear first portion 92a-1, a substantially linear third portion 92a-3 and a substantially linear fourth portion 92a-4 opposed to and parallel with the substantially linear first portion 92a-1. The first, second, third and fourth portions 92a-1, 92a-2, 92a-3 and 92a-4 of the channel light guide or optical channel light guide member 92a are connected together to form the substantially rectangular flame-like configuration as a whole similar to the configuration of the distributing light guide 56, in which an external contour with the substantially rectangular flame-like configuration of the channel light guide 92a is substantially equal in size to an internal contour with the substantially rectangular flame-like configuration of the distributing light guide 56 so as to be connected or in contact with to each other. An internal contour with the substantially rectangular flame-like configuration of the channel light guide 92a is substantially equal in size to an contour with the substantially rectangular shape of four side surfaces 30c, 30d, 30e and 30f of the surface lighting light guide 30 so as to be connected or in contact with to each other. The channel light guide or optical channel light guide member 92a is further composed of a plurality of optical channel elements 93a and a plurality of interposers 94a, in which the optical channel elements 93a and the adjacent interposers 94a are alternately aligned so as to form a substantially rectangular flame-like array as a whole, in such a manner that each of the optical channel elements 93a is positioned to be sandwiched by the adjacent interposers 94a. The interposers 94a are composed of a light transmitting solid member having a substantially transparent material having a refractive index lower than the refractive index of the optical channel elements 93a. The interposers 94a may substitute air for the light transmitting solid member since the refractive index (value=1) of the air is generally lower than that of the light transmitting solid member such as PMMA or PC. Each of the optical channel elements 93a has a substantially equal width and equal light input surface area, while each of the interposers 94a has a substantially variable width. The optical channel elements 93a are distributed variably in a pitch therebetween in a stepwise or continuous manner to form a first gradation pattern in such a manner that the quantity of the channel elements 93a increases from the four corners of the channel light guide portions 92a-1, 92a-2, 92a-3 and 92a-4 toward the four centers of the channel light guide portions 92a-1, 92a-2, 92a-3 and 92a-4. On the contrary, the interposers 94a are distributed variably in a width in a stepwise or continuous manner to form a second gradation pattern in such a manner that the width of the interposers 94a decreases from the four corners of the channel light guide portions 92a-1, 92a-2, 92a-3 and 92a-4 toward the four centers of the channel light guide portions 92a-1, 92a-2, 92a-3 and 92a-4. Therefore, light emitting from the LEDs 200a, 200b, 200c and 200d to input into the nonlinear i.e. annular distributing light guide member or portion 56 with the substantially rectangular flame-like configuration can output the light with a substantially uniform luminance along an entire length of the light output side surface or side surface portion 56-1d, 56-2d, 56-3d and 564d and resultantly a lighting with substantially uniform surface luminance or brightness can be produced from substantially entire areas of the surface lighting surface 30a of the surface lighting light guide member or portion 30. In FIG. 95 and FIG. 96, the light guide unit 153 is composed of the surface lighting light guide 30, the substantially rectangular flame-like channel light guide member 92a and the substantially rectangular flame-like distributing light guide 56, in which three light guides 30, 92a and 56 are connected one another in that order to form a single integrated composite unit. However, three light guides 30, 92a and 56 may be separated to be in contact with in that order to one another, or two light guides of the three light guides 30, 92a and 56 may form a composite, instead. Reference is made to showing a thirty sixth embodiment of the present invention, in which FIG. 97 is a schematic exploded perspective view showing a surface illuminator of a thirty sixth embodiment and FIG. 98 is a schematic top view showing the surface illuminator in the FIG. 97, in which this embodiment is a modification of the embodiment as shown in FIG. 89 and FIG. 90. As shown in FIG. 97 and FIG. 98, a surface illuminator is briefly composed of a light guide unit 154 and four numbers or sets of LEDs 200a, 200b, 200c and 200d. The light guide unit 154 is made of a light transmitting member having a substantially transparent material. The light guide unit 154 is composed of a surface lighting light guide member 30, a nonlinear light guide member or portion (i.e. distributing light guide member) 57 and an optical channel light guide member or portion 95″ disposed therebetween, in which the optical channel light guide member or portion 95″ is sandwiched laterally by the nonlinear light guide member 57 and the surface lighting light guide member 30. The nonlinear light guide member 57 is acting as a distributing light guide for distributing light along an entire length thereof. The nonlinear light guide member 57 is composed of an annular light guide member having a substantially rectangular flame-like, “O” shaped, flame-like or ring-like light guide member, in which the nonlinear light guide member 57 is further composed of a substantially linear first portion 57-1, a substantially linear second portion 57-2 opposed to and parallel with the substantially linear first portion 57-1, a substantially linear third portion 57-3 and a substantially linear fourth portion 57-4 opposed to and parallel with the substantially linear first portion 57-3. The nonlinear light guide member 57 is further provided with four corner surfaces 57i, 57h, 57j and 57k at the four corners of four substantially linear first, second, third and fourth portions 57-1, 57-2, 57-3 and 57-4, where the first, second, third and fourth portions 57-1, 57-2, 57-3 and 57-4 are connected to one another. The first, second, third and fourth distributing light guide portions 57-1, 57-2, 57-3 and 57-4 have rear side surfaces 57-1c, 57-2c, 57-3c and 57-4c and front side surfaces 57-1d, 57-2d, 57-3d and 57-4d opposed to the rear side surfaces 57-1c, 57-2c, 57-3c and 57-4c respectively, in which the distance between the rear and front side surfaces (57-1c, 57-2c, 57-3c and 57-4c) and (57-1d, 57-2d, 57-3d and 57-4d) are substantially equal or uniform. Four reflectors 40-1, 40-2, 40-3 and 404, each having a substantially V” shaped configuration are disposed in each center of the front side surfaces 57-1d, 57-2d, 57-3d and 57-4d of the distributing light guide portions 57-1, 57-2, 57-3 and 574. Each of the reflectors 40-1, 40-2, 40-3 and 40-4 is composed of opposed reflecting surfaces or portions (40-1a and 40-1b), (40-2a and 40-2b), (40-3a and 40-3b) and (404a and 404b). The LEDs 200a, 200b, 200c and 200d are disposed in contact with, adjacent to the rear side surface 57-1c, 57-2c, 57-3c and 574c near the centers thereof, so that each light emitting window of the LEDs 200a, 200b, 200c and 200d faces the opposed reflecting surfaces (40-1a and 40-1b), (40-2a and 40-2b), (40-3a and 40-3b) and (404a and 404b). The channel light guide or optical channel light guide member 95″ is composed of an annular channel light guide member having a substantially rectangular flame-like channel light guide member, “O” shaped, flame-like, loop-like or ring-like light guide member, in which the optical channel light guide member 95″ is further composed of a substantially linear first portion 95″-1, a substantially linear second portion 95″-2 opposed to and parallel with the substantially linear first portion 95″-1, a substantially linear third portion 95″-3 and a substantially linear fourth portion 95″-4 opposed to and parallel with the substantially linear first portion 95″-1. The first, second, third and fourth portions 95″-1, 95″-2, 95″-3 and 95″-4 of the channel light guide or optical channel light guide member 95″ are connected together to form the substantially flame-like configuration as a whole similar to the configuration of the distributing light guide 57, in which an external contour with the substantially rectangular flame-like configuration of the channel light guide 95″ is substantially equal in size to an internal contour with the substantially rectangular flame-like configuration of the distributing light guide 57 so as to be connected or in contact with to each other. An internal contour with the substantially rectangular flame-like configuration of the channel light guide 95″ is substantially equal in size to an contour with the substantially rectangular shape of four side surfaces 30c, 30d, 30e and 30f of the surface lighting light guide 30 so as to be connected or in contact with to each other. The channel light guide or optical channel light guide member 95″ is further composed of a plurality of optical channel elements 97″ and a plurality of interposers 98″, in which the optical channel elements 97″ and the adjacent interposers 98″ are alternately aligned so as to form a substantially rectangular flame-like array as a whole, in such a manner that each of the optical channel elements 97″ are positioned to be sandwiched by the adjacent interposers 98″. The interposers 98″ are composed of a light transmitting solid member having a substantially transparent material having a refractive index lower than the refractive index of the optical channel elements 97″. The interposers 98″ may substitute air for the light transmitting solid member since the refractive index (value=1) of the air is generally lower than that of the light transmitting solid member such as PMMA or PC. Each of the optical channel elements 97″ has a substantially equal width and equal light input surface area, while each of the interposers 98″ has a substantially variable width. The optical channel elements 97″ are distributed variably in a pitch therebetween in a stepwise or continuous manner to form a first gradation pattern in such a manner that the quantity of the channel elements 97″ increases from the centers of the channel light guide portions 95″-1, 95″-2, 95″-3 and 95″-4 toward the corners of the channel light guide portions 95″-1, 95″-2, 95″-3 and 95″-4. On the contrary, the interposers 98″ are distributed variably in a width in a stepwise or continuous manner to form a second gradation pattern in such a manner that the width of the interposers 98″ decreases from the centers of the channel light guide portions 95″-1, 95″-2, 95″-3 and 95″-4 toward the corners of the channel light guide portions 95″-1, 95″-2, 95″-3 and 95″4. Therefore, light emitting from the LEDs 200a, 200b, 200c and 200d to input into the nonlinear i.e. annular distributing light guide member or portion 57 with the substantially rectangular flame-like configuration can output the light with a substantially uniform luminance along an entire length of the light output side surface or side surface portion 57-1d, 57-2d, 57-3d and 57-4d and resultantly a lighting with substantially uniform surface luminance or brightness can be produced from substantially entire areas of the surface lighting surface 30a of the surface lighting light guide member or portion 30. In FIG. 97 and FIG. 98, the light guide unit 154 is composed of the surface lighting light guide 30, the substantially rectangular flame-like channel light guide member 95″ and the substantially rectangular flame-like distributing light guide 57, in which three light guides 30, 95″ and 57 are connected one another in that order to form a single integrated composite unit. However, three light guides 30, 95″ and 57 may be separated to be in contact with in that order to one another, or two light guides of the three light guides 30, 95″ and 57 may form a composite, instead. Reference is made to FIG. 99 and FIG. 100 showing a thirty seventh embodiment of the present invention, in which FIG. 99 is a schematic exploded perspective view showing a surface illuminator of the thirty seventh embodiment and FIG. 100 is a schematic top view showing the surface illuminator in the FIG. 99, in which this embodiment is a modification of the embodiment as shown in FIG. 97 and FIG. 98. As shown in FIG. 99 and FIG. 100, a surface illuminator is briefly composed of a light guide unit 155 and four numbers or sets of LEDs 200a, 200b, 200c and 200d. The light guide unit 155 is made of a light transmitting member having a substantially transparent material. The light guide unit 155 is composed of a surface lighting light guide member 30, a nonlinear light guide member or portion (i.e. distributing light guide member) 58 and an optical channel light guide member or portion 95″ disposed therebetween, in which the optical channel light guide member or portion 95″ is sandwiched laterally by the nonlinear light guide member 58 and the surface lighting light guide member 30. The nonlinear light guide member 58 is acting as a distributing light guide for distributing light along an entire length thereof. The nonlinear light guide member 58 is composed of an annular light guide member having a substantially rectangular flame-like, “O” shaped, flame-like or ring-like light guide member, in which the nonlinear light guide member 58 is further composed of a substantially linear first portion 58-1, a substantially linear second portion 58-2 opposed to and parallel with the substantially linear first portion 58-1, a substantially linear third portion 58-3 and a substantially linear fourth portion 58-4 opposed to and parallel with the substantially linear first portion 58-3. The nonlinear light guide member 58 is further provided with four corner surfaces 58i, 58h, 58j and 58k at the four corners of four substantially linear first, second, third and fourth portions 58-1, 58-2, 58-3 and 584, where the first, second, third and fourth portions 58-1, 58-2, 58-3 and 58-4 are connected to one another. The first, second, third and fourth distributing light guide portions 58-1, 58-2, 58-3 and 58-4 have rear side surfaces 58-1c, 58-2c, 58-3c and 58-4c and front side surfaces 58-1d, 58-2d, 58-3d and 58-4d opposed to the rear side surfaces 58-1c, 58-2c, 58-3c and 58-4c respectively. It is noted that each of the first, second, third and fourth distributing light guide portions 58-1, 58-2, 58-3 and 58-4 has a tapered configuration, in which the distributing light guide portions 58-1, 58-2, 58-3 and 58-4 have tapered rear side surfaces 58-1c, 58-2c, 58-3c and 58-4c, in which the distance between the tapered rear side surfaces 58-1c, 58-2c, 58-3c and 58-4c and the non-tapered side surfaces 58-1d, 58-2d, 58-3d and 58-4d decreases from the corner surfaces 58h, 58i, 58j and 58k toward the centers of the distributing light guide portions 58-1, 58-2, 58-3 and 58-4. On the contrary, in the thirty six embodiment as shown in FIG. 98 and FIG. 99, the distance between the rear and front side surfaces (57-1c, 57-2c, 57-3c and 57-4c) and (57-1d, 57-2d, 57-3d and 57-4d) are substantially equal or uniform. Four reflectors 40-1, 40-2, 40-3 and 40-4, each having a substantially V″ shaped configuration are disposed in each center of the front side surfaces 58-1d, 58-2d, 58-3d and 58-4d of the distributing light guide portions 58-1, 58-2, 58-3 and 58-4. Each of the reflectors 40-1, 40-2, 40-3 and 40-4 is composed of opposed reflecting surfaces or portions (40-1a and 40-1b), (40-2a and 40-2b), (40-3a and 40-3b) and (40-4a and 40-4b). The LEDs 200a, 200b, 200c and 200d are disposed in contact with, adjacent to the rear side surface 58-1c, 58-2c, 58-3c and 58-4c near the centers thereof, so that each light emitting window of the LEDs 200a, 200b, 200c and 200d faces the opposed reflecting surfaces (40-1a and 40-1b), (40-2a and 40-2b), (40-3a and 40-3b) and (40-4a and 40-4b). The channel light guide or optical channel light guide member 95″ is composed of an annular channel light guide member having a substantially rectangular flame-like channel light guide member, “O” shaped, flame-like, loop-like or ring-like light guide member, in which the optical channel light guide member 95″ is further composed of a substantially linear first portion 95″-1, a substantially linear second portion 95″-2 opposed to and parallel with the substantially linear first portion 95″-1, a substantially linear third portion 95″-3 and a substantially linear fourth portion 95″-4 opposed to and parallel with the substantially linear first portion 95″-1. The first, second, third and fourth portions 95″-1, 95″-2, 95″-3 and 95“4 of the channel light guide or optical channel light guide member 95″ are connected together to form the substantially flame-like configuration as a whole similar to the configuration of the distributing light guide 58, in which an external contour with the substantially rectangular flame-like configuration of the channel light guide 95″ is substantially equal in size to an internal contour with the substantially rectangular flame-like configuration of the distributing light guide 58 so as to be connected or in contact with to each other. An internal contour with the substantially rectangular flame-like configuration of the channel light guide 95″ is substantially equal in size to an contour with the substantially rectangular shape of four side surfaces 30c, 30d, 30e and 30f of the surface lighting light guide 30 so as to be connected or in contact with to each other. The channel light guide or optical channel light guide member 95″ is further composed of a plurality of optical channel elements 97″ and a plurality of interposers 98″, in which the optical channel elements 97″ and the adjacent interposers 98″ are alternately aligned so as to form a substantially rectangular flame-like array as a whole, in such a manner that each of the optical channel elements 97″ are positioned to be sandwiched by the adjacent interposers 98″. The interposers 98″ are composed of a light transmitting solid member having a substantially transparent material having a refractive index lower than the refractive index of the optical channel elements 97″. The interposers 98″ may substitute air for the light transmitting solid member since the refractive index (value=1) of the air is generally lower than that of the light transmitting solid member such as PMMA or PC. Each of the optical channel elements 97″ has a substantially equal width and equal light input surface area, while each of the interposers 98″ has a substantially variable width. The optical channel elements 97″ are distributed variably in a pitch therebetween in a stepwise or continuous manner to form a first gradation pattern in such a manner that the quantity of the channel elements 97″ increases from the centers of the channel light guide portions 95″-1, 95″-2, 95″-3 and 95″-4 toward the corners of the channel light guide portions 95″-1, 95″-2, 95″-3 and 95″-4. On the contrary, the interposers 98″ are distributed variably in a width in a stepwise or continuous manner to form a second gradation pattern in such a manner that the width of the interposers 98″ decreases from the centers of the channel light guide portions 95″-1, 95″-2, 95″-3 and 95″-4 toward the corners of the channel light guide portions 95″-1, 95″-2, 95″-3 and 95″-4. Therefore, light emitting from the LEDs 200a, 200b, 200c and 200d to input into the nonlinear i.e. annular distributing light guide member or portion 58 with the substantially rectangular flame-like configuration can output the light with a substantially uniform luminance along an entire length of the light output side surface or side surface portion 58-1d, 58-2d, 58-3d and 58-4d and resultantly a lighting with substantially uniform surface luminance or brightness can be produced from substantially entire areas of the surface lighting surface 30a of the surface lighting light guide member or portion 30. In FIG. 99 and FIG. 100, the light guide unit 155 is composed of the surface lighting light guide 30, the substantially rectangular flame-like channel light guide member 95″ and the substantially rectangular flame-like distributing light guide 58, in which three light guides 30, 95″ and 58 are connected one another in that order to form a single integrated composite unit. However, three light guides 30, 95″ and 58 may be separated to be in contact with in that order to one another, or two light guides of the three light guides 30, 95″ and 58 may form a composite, instead. Reference is made to showing a thirty eighth embodiment of the present invention, in which FIG. 101 is a schematic exploded perspective view showing a surface illuminator of the thirty eighth embodiment and FIG. 102 is a schematic top view showing the surface illuminator in the FIG. 101. This embodiment is a modification of the embodiment as shown in FIG. 93 and FIG. 94 and the embodiment as shown in FIG. 97 and FIG. 98 that these two embodiments are combined. As shown in FIG. 101 and FIG. 102, a surface illuminator is briefly composed of a light guide unit 156 and eight numbers or sets of LEDs 200a, 200b, 200c, 200d, 200e, 200f, 200g and 200h. Since this embodiment enables to use eight numbers or sets of LEDs, a surface illuminator having a comparatively large surface area with a sufficient surface brightness and a uniform brightness along that entire surface area can be obtained and the surface illuminator is suitable for use in backlighting or front-lighting of the liquid crystal display devices (LCDs) with a comparatively large display screen. The light guide unit 156 is made of a light transmitting member having a substantially transparent material. The light guide unit 156 is composed of a surface lighting light guide member 30, a nonlinear light guide member or portion (i.e. distributing light guide member) 57 and an optical channel light guide member or portion 95″ disposed therebetween, in which the optical channel light guide member or portion 95″ is sandwiched laterally by the nonlinear light guide member 57 and the surface lighting light guide member 30. The nonlinear light guide member 57 is acting as a distributing light guide for distributing light along an entire length thereof. The nonlinear light guide member 57 is composed of an annular light guide member having a substantially rectangular flame-like, “O” shaped, flame-like or ring-like light guide member, in which the nonlinear light guide member 57 is further composed of a substantially linear first portion 57-1, a substantially linear second portion 57-2 opposed to and parallel with the substantially linear first portion 57-1, a substantially linear third portion 57-3 and a substantially linear fourth portion 57-4 opposed to and parallel with the substantially linear first portion 57-3. The nonlinear light guide member 57 is further provided with four corner side surfaces 57i, 57h, 57j and 57k at the four corners of four substantially linear first, second, third and fourth portions 57-1, 57-2, 57-3 and 57-4, where the first, second, third and fourth portions 57-1, 57-2, 57-3 and 57-4 are connected to one another. The first, second, third and fourth distributing light guide portions 57-1, 57-2, 57-3 and 57-4 have rear side surfaces 57-1c, 57-2c, 57-3c and 57-4c and front side surfaces 57-1d, 57-2d, 57-3d and 57-4d opposed to the rear side surfaces 57-1c, 57-2c, 57-3c and 574c respectively. Four reflectors 40-1, 40-2, 40-3 and 40-4 having substantially V” shaped configuration are disposed in each center of the front side surfaces 57-1d, 57-2d, 57-3d and 57-4d of the distributing light guide portions 57-1, 57-2, 57-3 and 57-4. Each of the reflectors 40-1, 40-2, 40-3 and 40-4 is composed of opposed reflecting surfaces or portions (40-1a and 40-1b), (40-2a and 40-2b), (40-3a and 40-3b) and (404a and 404b). The LEDs 200a, 200b, 200c and 200d are disposed relative to the reflectors 40-1, 40-2, 40-3 and 40-4 respectively so that the LEDs 200a, 200b, 200c and 200d are in contact with or adjacent to the rear side surface 57-1c, 57-2c, 57-3c and 57-4c near the centers thereof, so that each light emitting window of the LEDs 200a, 200b, 200c and 200d faces the opposed reflecting surfaces (40-1a and 40-1b), (40-2a and 40-2b), (40-3a and 40-3b) and (40-4a and 40-4b). Further, the LEDs 200e, 200f, 200g and 200h are disposed to be in contact with or adjacent to the corner side surfaces 57i, 57h, 57j and 57k. The channel light guide or optical channel light guide member 95″ is composed of an annular channel light guide member having a substantially rectangular flame-like channel light guide member, “O” shaped, flame-like, loop-like or ring-like light guide member, in which the optical channel light guide member 95″ is further composed of a substantially linear first portion 95″-1, a substantially linear second portion 95″-2 opposed to and parallel with the substantially linear first portion 95″-1, a substantially linear third portion 95″-3 and a substantially linear fourth portion 95″-4 opposed to and parallel with the substantially linear first portion 95″-1. The first, second, third and fourth portions 95″-1, 95″-2, 95″-3 and 95″-4 of the channel light guide or optical channel light guide member 95″ are connected together to form the substantially flame-like configuration as a whole similar to the configuration of the distributing light guide 57, in which an external contour with the substantially rectangular flame-like configuration of the channel light guide 95″ is substantially equal in size to an internal contour with the substantially rectangular flame-like configuration of the distributing light guide 57 so as to be connected or in contact with to each other. An internal contour with the substantially rectangular flame-like configuration of the channel light guide 95″ is substantially equal in size to an contour with the substantially rectangular shape of four side surfaces 30c, 30d, 30e and 30f of the surface lighting light guide 30 so as to be connected or in contact with to each other. The channel light guide or optical channel light guide member 95″ is further composed of a plurality of optical channel elements 97″ and a plurality of interposers 98″, in which the optical channel elements 97″ and the adjacent interposers 98″ are alternately aligned so as to form a substantially rectangular flame-like array as a whole, in such a manner that each of the optical channel elements 97″ are positioned to be sandwiched by the adjacent interposers 98″. The interposers 98″ are composed of a light transmitting solid member having a substantially transparent material having a refractive index lower than the refractive index of the optical channel elements 97″. The interposers 98″ may substitute air for the light transmitting solid member since the refractive index (value=1) of the air is generally lower than that of the light transmitting solid member such as PMMA or PC. Each of the optical channel elements 97″ has a substantially equal width and equal light input surface area, while each of the interposers 98″ has a substantially variable width. The optical channel elements 97″ are distributed variably in a pitch therebetween in a stepwise or continuous manner to form a first gradation pattern in such a manner that the quantity of the channel elements 97″ increases from the centers of the channel light guide portions 95″-1, 95″-2, 95″-3 and 95″-4 toward the corners of the channel light guide portions 95″-1, 95″-2, 95″-3 and 95″-4. Further, the quantity or density of the channel elements 97″ increases from the corners of the channel light guide portions 95″-1, 95″-2, 95″-3 and 95″-4 toward the centers of the channel light guide portions 95″-1, 95″-2, 95″-3 and 95″-4. On the contrary, the interposers 98″ are distributed variably in a width in a stepwise or continuous manner to form a second gradation pattern in such a manner that the width of the interposers 98″ decreases from the centers of the channel light guide portions 95″-1, 95″-2, 95″-3 and 95″-4 toward the corners of the channel light guide portions 95″-1, 95″-2, 95″-3 and 95″-4. Further, the interposers 98″ are distributed variably in a width in a stepwise or continuous manner to form a second gradation pattern in such a manner that the width of the interposers 98″ decreases from the corners of the channel light guide portions 95″-1, 95″-2, 95″-3 and 95″-4 toward the centers of the channel light guide portions 95″-1, 95″-2, 95″-3 and 95″-4. Therefore, light emitting from the LEDs 200a, 200b, 200c, 200d, 200e, 200f, 200g and 200h to input into the nonlinear i.e. annular distributing light guide member or portion 57 with the substantially rectangular flame-like configuration can output the light with a substantially uniform luminance along an entire length of the light output side surface or side surface portion 57-1d, 57-2d, 57-3d and 57-4d and resultantly a lighting with substantially uniform surface luminance or brightness can be produced from substantially entire areas of the surface lighting surface 30a of the surface lighting light guide member or portion 30. In FIG. 101 and FIG. 102, the light guide unit 156 is composed of the surface lighting light guide 30, the substantially rectangular flame-like channel light guide member 95″ and the substantially rectangular flame-like distributing light guide 57, in which three light guides 30, 95″ and 57 are connected one another in that order to form a single integrated composite unit. However, three light guides 30, 95″ and 57 may be separated to be in contact with in that order to one another, or two light guides of the three light guides 30, 95″ and 57 may form a composite, instead. The surface illuminator of the present invention may be typically used with the liquid crystal devices such as liquid crystal displays as backlighting or front-lighting, further the surface illuminator of the present invention may be used for other various applications of lighting or illumination such as lighting fixtures, illumination of timepieces, film viewers, night lights, lighted posters, emergency lights and the backlighting or front-lighting of other passive or non-emissive devices or displays such as electro-chromic devices or displays and plasma addressed liquid crystal devices. In the various embodiments described above, the first light guide member, the channel light guide member channel light guide member and the second light guide member are interposed laterally in that order. In stead of a lateral disposition (positioning) of these three members, a vertical disposition of these three members may be applied, in which the first light guide member, the channel light guide member channel light guide member and the second light guide member may be interposed vertically in that order. In the vertical disposition, these three members each may be composed of a plate and the three members may be composed to form a laminate or a stack. These lateral and vertical dispositions may be selected according to the purpose. Although illustrative embodiments of the present invention have been described referring to the accompanying drawings, it is to be understood that the present invention is not limited to those embodiments and that various changes, modifications or equivalents may be made in the present invention by those skilled in the art without departing from the spirit or the scope of the present invention and the appended claims. |
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description | This application claims the benefit of Chinese Patent Application No. 201010576003.1 filed Nov. 26, 2010, which is hereby incorporated by reference in its entirety. The embodiments described herein relate to an interface device, in particular to an mechanical trigger interface device for use in the collimator for an X-ray imaging apparatus, a collimator including the interface device and the assemble and disassemble method thereof. In various X-ray imaging apparatuses such as CT scanning and imaging apparatuses, the mechanical interface of the collimator directly relates to the safety of the suspending weight (e.g. fall of collimator), the satisfactory of users and the service cost. However, in the conventional X-ray imaging apparatus, usually a bolt is used to connect the collimator to the flange of the tube. Such a way of connection requires certain tightness and torque and generally requires the use of an adhesive, besides, the process and effect of installation are invisible. In addition, factors like mis-operation and loose or aging and fractured bolt will result in a collimator fall in practical application and will thus cause accidents. Therefore, a safer interface device for collimator that can be easily installed and can reduce the risk of collimator fail is needed. The embodiments described herein provide a safe and reliable mechanical trigger interface device of a collimator that can be easily assembled and dissembled, a collimator including the interface device, and the assemble and dissemble method thereof so as to overcome the defects in the prior art. According to a first aspect, a mechanical trigger interface device of a collimator is provided. The interface device includes a locating ring configured to mount at the outlet of the tube flange on the collimator housing; and a tongue set fixed on the locating ring, wherein the outstretching direction of the tongue is towards the center of the locating ring. According to one embodiment, the tongue set further includes a tongue set housing with a tongue outlet provided on one end face thereof; a tongue located in the tongue set housing and including a head that can pop out from the tongue and a tail that has a pullback section; and a trigger pin for controlling popping out of the tongue. According to one embodiment, the tongue set further includes a block plate, which is connected to an end of the tongue set housing opposite to the tongue outlet for covering the pullback section provided at the tongue tail. Preferably, according to one embodiment, the mechanical trigger interface device of a collimator includes at least three tongue sets which are uniformly disposed on the locating ring. According to one embodiment, the mechanical trigger interface device of a collimator further includes a rotating lock knob, which is provided on the locating ring for controlling rotation of the collimator. According to a second aspect, a collimator for X-ray imaging apparatus is provided. The X-ray imaging apparatus includes a collimator housing and a tube. In addition, the collimator further includes a locating ring configured to be mounted at the outlet of the tube flange on the collimator housing; and a tongue set which is fixed on the locating ring, wherein the outstretching direction of the tongue is towards the center of the locating right. According to one embodiment, the tongue set further includes a tongue set housing with a tongue outlet provided on one end face thereof; a tongue located in the tongue set housing and includes a head that can pop out from the tongue and a tail that has a pullback section; and a trigger pin for controlling popping out of the tongue. According to one embodiment, the tongue set further includes a block plate, which is connected to an end of the tongue set housing opposite to the tongue outlet for covering the pullback section provided at the tongue tail. Preferably, according to one embodiment, the collimator includes at least three tongue sets which are uniformly disposed on the locating ring. According to one embodiment, the tongue set further includes a rotating lock knob, which is provided on the locating ring for controlling rotation of the collimator. According to a third aspect, a method of assembling the collimator for use in a CT scanning and imaging apparatus according to the second aspect is provided. The method includes rotating the operation platform system to the assembling position to place the tube and the tube flange in position; placing the collimator in the assembling position and pressing the trigger pin; and mounting the block plate. According to a fourth aspect, a method of disassembling the collimator for use in a CT scanning and imaging apparatus according to the second aspect is provided. The method includes rotating the operation platform system to the disassembling position; removing the block plate; pulling back the tongue; and moving the collimator away from the operation platform system. According to a fifth aspect, an X-ray imaging apparatus is provided. The X-ray imaging apparatus includes the mechanical trigger interface device of a collimator according to the first aspect or the collimator for X-ray imaging apparatus according to the second aspect. In the mechanical trigger interface device of a collimator, the collimator includes the interface device, and the assemble and disassemble method thereof, the tube flange is reliably connected to the collimator without using any special assembling tool or adhesive, so the assembling is convenient and time-saving. On the contrary, a tool is needed when disassembling it, thus ensuring a reliable locking during operation of the collimator. The present invention will be described in detail below by means of embodiments and in conjunction with the drawings, wherein the same or similar components are indicated by the same reference numbers. As shown in FIG. 1, which shows a schematic drawing of the mechanical trigger interface device of a collimator including a locating ring 100 and a tongue set 102. The locating ring is configured to be adapted to mounting at the outlet of the tube flange 106 on the collimator housing 104. For example, the size of the locating ring 100 is configured to be adapted to the size of the outlet of the tube flange 106, as shown in FIG. 2. The tongue set is adapted to be fixed on the locating ring 100, for example, by bolting, riveting, jointing, bonding, etc. The outstretching direction of the tongue is towards the center of the locating ring, namely, towards the tube flange 106, as shown in FIG. 2. As shown in FIG. 3, in one embodiment, the tongue set 102 further includes a tongue set housing 108, a tongue 110, and a trigger pin 112. The tongue set housing 108 is substantially a cuboid, with one end face thereof being provided with a tongue outlet 114 and one side face thereof being provided with a trigger pin hole 116. The tongue 110 can be assembled into the tongue set housing 108, and can be configured in such a way that its head 118 can pop out from the tongue outlet 114 and its tail has a pullback section. A locating hole 120 is provided on the tongue 110 as well as a slotted hole 122 connected to the locating hole 120. The locating hole 120 is wider than the slotted hole 122. The head 118 of the tongue is made to be wider than the rest parts of the tongue, so that after nesting the driving spring 124 into the tongue 110, the tail of the tongue 110 passes through the opening on the block plate 126 that can allow its passage and is assembled into the tongue set housing 108. The trigger pin 112 is made to be adapted to mounting into the trigger pin hole 116 on the tongue set housing 108. In other words, after being mounted, the trigger pin 112 can move up and down in the trigger pin hole 116 when being pressed so as to control the pop out of the tongue 110. Specifically, a locating section 128 (e.g. including but not limited to a nut that can be connected to the lower part of the trigger pin 112) is provided at the lower part of the trigger pin 112. The dimension of the locating section 128 is greater than the width of the slotted hole 122, but is adapted to be inserted into the locating hole 120 on the tongue 110. The body of the trigger pin 112 is thinner than the locating section 128 so as to be movable in the slotted hole 122. In addition, a trigger sprint 130 is in socket joint with the body of the trigger pin 112. As shown in FIG. 4, after mounting, the locating section 128 at the lower part of the trigger pin 112 is in the locating hole 120 on the tongue 110, the driving spring 124 is compressed between the head 118 of the tongue and the block plate 126, the trigger spring 130 is in a natural state, and the tongue 110 is in a retracting state at this time. When the trigger pin 112 is pressed, the locating section 128 at the lower part of the trigger pin 112 is detached downwards from the locating hole 120 on the tongue 110, and the tongue 110 is popped out from the tongue outlet 114 under the force of the driving spring 124. The popping length mainly depends on the length of the slotted hole 122, so an appropriate tongue popping length can be obtained by properly setting the length of the slotted hole 122. Meanwhile, the trigger spring 130 is compressed, as shown in FIG. 5. Furthermore, a pull back section is provided at the tail of the tongue 110. In one embodiment, the pull back section includes a nut 134, a bolt 135, and a tongue tip 138 connected through a screw hole 132 at the tail of the tongue 110, as shown in FIG. 3. When pulling the tongue 110 by the pull back section (as shown by the arrow in FIG. 6), the head 118 of the tongue 110 moves towards the inside of the tongue set housing 108, and the driving spring 12 is compressed. When the locating hole 120 on the tongue is moved to be aligned with the locating section 128 at the lower part of the trigger pin 112, the trigger pin 112 moves upwards under the force of the trigger spring 130, so that the locating section 128 at the lower part of the trigger pin 112 enters the locating hole 120 on the tongue so as to lock the tongue 110, as shown in FIG. 6. As shown in FIGS. 3 and 5, in one embodiment, the tongue set 102 further includes a block plate 140 that can be connected to an end of the tongue set housing opposite to the tongue outlet 114 for covering the pull back section provided at the tail of the tongue, thus preventing mis-operation. In one embodiment, the mechanical trigger interface device of a collimator includes at least three tongue sets 102 which are uniformly disposed on the locating ring 100. Preferably, the mechanical trigger interface device of a collimator includes three tongue sets which are disposed on the locating ring with an interval of 120° between each other, as shown in FIGS. 1 and 2. In one embodiment, the mechanical trigger interface device of a collimator further includes a rotating lock knob 142, which is provided on the locating ring 100 for controlling rotation of the collimator, as shown in FIGS. 1 and 2. FIG. 2 is a schematic drawing of the collimator including the mechanical trigger interface device of a collimator according to the above embodiment. The locating ring 100 is mounted at the outlet of the tube flange 106 on the collimator housing 104 by bolting, riveting or other connection means. Likewise, the three tongue sets 102, for example, are mounted onto the locating ring 100. After pressing the trigger pin 112 on the tongue set 102, the tongue 110 outstretches towards the center of the locating ring to be against the tube flange 106 so as to fix it at the central position. The mechanical trigger interface device of a collimator according to the above embodiments makes it easy to install the collimator and prevents mis-disassembling. The assembling process mainly includes the following steps: rotating the operation platform system to the assembling position to place the tube and the tube flange in position; placing the collimator in the assembling position and pressing the trigger pin; and mounting the block plate. Correspondingly, the disassembling process mainly includes the steps of rotating the operation platform system to the disassembling position; removing the block plate; pulling back the tongue; and moving the collimator away from the operation platform system. The mechanical trigger interface device of a collimator according to the above embodiments or the collimator including the interface device can be used in an X-ray scanning and imaging apparatus. Since this can be easily realized by those skilled in the art, it is not described in detail herein. While the present invention has been described in detail by specific embodiments, it is not limited to the specific embodiments. Those skilled in the art shall understand that various modifications, equivalent substitutions and changes can be made to the present invention, for example, the trigger spring can be provided between the lower part of the trigger pin and the bottom face of the tongue set housing, or the driving spring can be provided at the tail end of the tongue. A bayonet can be provided at a side of the tongue, so that the tongue is popped out or locked by poking the trigger pin. Such variations, however, should fall within the protection scope of the present invention as long as they are not departing from the spirit of the present invention. In addition, some terms used in the description and claims of the present application, for example “on” and “under” and so on are not intended to limit but to facilitate the description. Moreover, expressions like “one embodiment” and “another embodiment” used in the above texts indicate different embodiments, but of course, they can be implemented, all or in part, in one embodiment. |
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041636902 | claims | 1. A nuclear reactor fuel assembly spacer grid for supporting and spacing a plurality of elongated fuel elements with their longitudinal axes in parallel comprising: at least two generally rectangular first plates, second plates, and a plurality of substantially flat rectangular third plates, each having lengthwise edges disposed transversely with respect to the longitudinal axes of the fuel elements and widthwise edges disposed generally parallel to the longitudinal axes of the fuel elements, and oppositely disposed faces bound perimetrically by said lengthwise and widthwise edges; a peripheral band circumscribing the spacer grid; said peripheral band having an inner face and an outer face; said lengthwise edges of said first and second plates transversely cut by slots each along a respective lengthwise edge thereof for mutually interlocking said first and second plates as a pair with said third plates; one of said first and one of said second plates being generally disposed in longitudinally spaced and inverted relation with respect to each other so that said slots on said respective first and second plates are oriented in opposite directions to form a first set of paired plates each having spaced cantilevered panels traversing the longitudinal space such that a portion of each panel is in transverse contact with the opposing plate of the pair; other first and second plates being relatively longidudinally spaced and inverted to form a second set of paired plates similar to said first set of paired plates; said first and second sets of paired plates being further disposed to perpendicularly intersect each other set and the third plates to mutually interlock therewith; said widthwise edges of the first, second, and third plates being in communication with the inner face of the peripheral band to form a plurality of cells having a substantially open cross-section through which the fuel elements protrude; a plurality of protrusions extending into the cells from one face of the first and second plates, from the inner face of the peripheral band, and from both faces of the third plates; said protrusions of the first and second plates being resilient; said protrusions of the inner face of the prripheral band being rigid; and said protrusions on one face of the third plate being rigid and the protrusions on the opposite face of the third plates being resilient. 2. A fuel assembly spacer grid according to claim 1 wherein a first plurality of said third plates is disposed parallel to and on either side of said first set of paired plates so that the rigid protrusions of the plates of said first plurality of third plates are orientated toward said first set of paired plates; a second plurality of third plates is disposed parallel to and on either side of said second set of paired plates so that the rigid protrusion of the plates of said second plurality of third plates are orientated toward said second set of paired plates; and said second plurality of third plates being inverted and perpendicularly disposed with respect to said first plurality of third plates. 3. A fuel assembly spacer grid according to claim 2 wherein said protrusions of said first, second, and third plates, of said peripheral band include at least one aperture. 4. A fuel assembly spacer grid according to claim 3 wherein said first, second, and third plates, and said peripheral band are disposed so that said cells each has two adjacent sides with resilient protrusions projecting into said cell opposite two adjacent sides with rigid protrusions projecting into said cell. 5. A spacer grid for supporting and spacing fuel elements comprising: a pair of slotted first plates generally disposed in longitudinally spaced and inverted relation having spaced cantilevered panels traversing said longitudinal space such that a portion of each panel is in transverse contact with the opposing plate of the pair; a pair of slotted second plates generally disposed in longitudinally spaced and inverted relation having spaced cantilevered panels traversing said longitudinal space such that a portion of each panel is in transverse contact with the opposing plate of the pair; a plurality of third plates; a peripheral band; said pair of slotted first plates and said pair of slotted second plates being disposed to perpendicularly intersect each other and said third plates to mutually interlock therewith; said peripheral band being in communication with said mutually interlocked plates to form a plurality of cells through which the fuel elements protrude. 6. A spacer grid as defined in claim 5 wherein said cantilevered panels of the first plates and the second plates include resilient protrusions projecting a portion of said panels; said third plates include a plurality of resilient protrusions projecting one face and rigid protrusions projecting the opposite face; said peripheral band includes rigid protrusions projecting the face of the cells side of the band; and said first; second and third plates being disposed so that each of said cells has two adjacent sides with resilient protrusions projecting into said cell opposite two adjacent sides with rigid protrusions projecting into said cells. 7. A spacer grid as defined in claim 6 wherein said peripheral band includes a spring like member formed on the face of the peripheral band opposite said cells. 8. A spacer grid as defined in claim 7 wherein said cantilevered panels are arcuate. |
claims | 1. A method for producing nuclear fuel products, the method comprising:receiving metallic or intermetallic uranium-based fuel particle cores,providing at least one physical vapour deposited coating layer surrounding the fuel particle core, the physical vapour deposited coating layer having a layer thickness between 5 nm and 2 μm, andembedding the coated fuel particles in a matrix material so as to form a powder mixture of coated fuel particles and matrix material. 2. The method according to claim 1, wherein embedding the coated fuel particles in a matrix material comprises obtaining a powder dispersion of the fuel particles and the solid matrix powder material. 3. The method according to claim 1, wherein the method furthermore comprises compacting the powder mixture of coated fuel particles and matrix material by pressing. 4. The method according to claim 1, wherein providing at least one physical vapour deposited coating layer comprises sputtering a coating layer having a thickness between 100 nm and 2 μm on the fuel particle core. 5. The method according to claim 1, wherein the method furthermore comprises annealing the provided coating layer. 6. The method according to claim 1, wherein providing at least one physical vapour deposited coating layer comprises providing at least one physical vapour deposited coating layer comprising inhibitor elements for inhibiting formation of an interaction layer between the coated fuel particles and the matrix material. 7. The method according to claim 6, wherein the coating layer comprises ZrN or Si to avoid interaction between the coated fuel particles and the matrix material. 8. The method according to claim 1, wherein providing at least one physical vapour deposited coating layer comprises providing at least one physical vapour deposited coating layer comprising neutron poisons. 9. The method according to claim 8, wherein the at least one physical vapour deposited coating layer comprising neutron poisons has a layer thickness between 100 nm and 200 nm. 10. The method according to claim 1, wherein providing the at least one physical vapour deposited coating layer comprises one or more of providing a single coating layer comprising both neutron poisons and inhibitor elements using co-deposition and providing a plurality of coating layers, each layer comprising one or more elements for introducing an additional functionality to the fuel particles. 11. The method according to claim 1, wherein the providing at least one physical vapour deposited coating layer is performed at room temperature. 12. A nuclear fuel product comprising a matrix material and nuclear fuel particles embedded therein, said fuel product based on a powder mixture of the matrix material and the nuclear fuel particles, the nuclear fuel particles comprising a metallic or intermetallic uranium-based fuel particle core and at least one physical vapour deposited coating layer surrounding the fuel particle core, the at least one physical vapour deposited coating layer having a thickness between 5 nm and 2 μm. 13. The nuclear fuel product according to claim 12, wherein the powder mixture is a powder dispersion of the fuel particles and the solid matrix powder material, and/or wherein the powder mixture of matrix material and coated fuel particles are compacted. 14. The nuclear fuel product according to claim 12, wherein the physical vapour deposited coating layer has a thickness between 100 nm and 2 μm and/or wherein the at least one physical vapour deposited coating is an amorphous coating layer and/or wherein the at least one physical vapour deposited coating layer is annealed. 15. The nuclear fuel product according to claim 12, wherein the at least one physical vapour deposited coating layer comprises inhibitor elements for inhibiting formation of an interaction layer of the nuclear fuel particle with the matrix material and/or inhibiting the negative effects of this interaction layer formation on the behaviour of the fuel during its use. 16. The nuclear fuel product according to claim 15, wherein the inhibitor elements comprise one of or a combination of Si, Zr, Nb, U, Mo, Al, Ti, As, Mg, Ge, Sn, Pb, Bi, Se, Sb or Te, an oxide thereof, a nitride thereof or a carbide thereof. 17. The nuclear fuel product according to claim 12, wherein the at least one physical vapour deposited coating layer comprises neutron poisons. 18. The nuclear fuel product according to claim 17, wherein the neutron poisons comprise one of or a combination of B, Sm, Gd, Dy, Ag, In, Cd, Er, Hf, Eu or Ta. 19. The nuclear fuel product according to claim 12, wherein the at least one physical vapour deposited coating layer comprises a single coating layer comprising both neutron poisons and inhibitor elements obtained by co-deposition and/or wherein the at least one physical vapour deposited coating layer comprises a stack of at least two layers, one layer comprising neutron poisons, another layer comprising inhibitor elements. 20. The nuclear fuel product according to claim 12, wherein the metallic or intermetallic uranium-based core comprise one or a combination of uranium alloys, uranium silicides or aluminides. 21. The nuclear fuel product according to claim 12, the nuclear fuel product being in the shape of a fuel plate or fuel rod. 22. A nuclear installation for generating neutrons, the nuclear installation comprising a fuel element that is a nuclear fuel product as recited in claim 12. |
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claims | 1. A fission process reactor unit, comprising:a radioactive element;a cobalt 59 (Co-59) layer;a Nuclear Thermionic Avalanche Cell (NTAC); anda thermoelectric generator,wherein:a fission process of the radioactive element releases neutrons to the Co-59 layer to breed cobalt 60 (Co-60);the NTAC receives gamma rays from the fission process, a by-product of the fission process, and the bred Co-60 to generate direct current (DC) power; andthe thermoelectric generator receives thermal energy from the radioactive element and the NTAC to generate DC power. 2. The fission process reactor unit of claim 1, wherein the radioactive element comprises uranium 235 (U-235) and the by-product of the fission process is cesium 137 (Cs-137). 3. The fission process reactor unit of claim 2, wherein the U-235 is a fuel rod and the fission process is controlled by a primary neutron source rod controllably inserted or removed from the fuel rod. 4. The fission process reactor unit of claim 3, wherein the Co-59 layer at least partially encircles the U-235 fuel rod. 5. The fission process reactor unit of claim 4, wherein the Co-59 layer is disposed between the U-235 fuel rod and the NTAC. 6. The fission process reactor unit of claim 5, wherein the NTAC is disposed between the Co-59 layer and the thermoelectric generator. 7. The fission process reactor unit of claim 6, wherein the NTAC and the thermoelectric generator are connected in tandem to a same DC bus or load. 8. The fission process reactor unit of claim 6, wherein the NTAC comprises a photoionic electron emitter separated from an electron getter electrode by a thermionic vacuum gap. 9. A reactor system, comprising:a containment vessel; andone or more fission process reactor units supported within the containment vessel, each of the one or more fission process reactor units comprising:a radioactive element;a cobalt 59 (Co-59) layer;a Nuclear Thermionic Avalanche Cell (NTAC); anda thermoelectric generator,wherein:a fission process of the radioactive element releases neutrons to the Co-59 layer to breed cobalt 60 (Co-60);the NTAC receives gamma rays from the fission process, a by-product of the fission process, and the bred Co-60 to generate direct current (DC) power; andthe thermoelectric generator receives thermal energy from the radioactive element and the NTAC to generate DC power. 10. The reactor system of claim 9, wherein the one or more fission process reactor units are twenty five or more fission process reactor units. 11. The reactor system of claim 9, wherein the radioactive element comprises uranium 235 (U-235) and the by-product of the fission process is cesium 137 (Cs-137). 12. The reactor system of claim 11, wherein the Co-59 layer at least partially encircles the U-235 fuel rod. 13. The reactor system of claim 12, wherein the Co-59 layer is disposed between the U-235 fuel rod and the NTAC and the NTAC is disposed between the Co-59 layer and the thermoelectric generator. 14. The reactor system of claim 13, wherein each of the one or more fission process reactor units are connected to a same DC bus. 15. The reactor system of claim 14, wherein the NTAC comprises a photoionic electron emitter separated from an electron getter electrode by a thermionic vacuum gap. 16. The reactor system of claim 9, further comprising a fluid circulated within the containment vessel. 17. The reactor system of claim 16, wherein the fluid is argon gas. |
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description | This application claims priority to German patent application number 10 2004 044 626.1, filed Sep. 13, 2004, which is incorporated herein by reference in its entirety. The invention concerns a method for investigating transport processes in a preferably biological specimen, a laser light beam being guided by means of a scanning apparatus line by line over the specimen within definable specimen regions, and the light proceeding from the specimen being detected by means of a detection apparatus. Methods of the kind under discussion here have been known in practical use for some time in a variety of embodiments. Of the known methods, only fluorescence recovery after photobleaching (FRAP), fluorescence loss in photobleaching (FLIP), or photoactivation will be mentioned by way of example. It is characteristic of these methods that a definable region of interest (ROI) is illuminated in a particular fashion. In FRAP, FLIP, or photoactivation experiments, this so-called manipulation illumination is characterized, for example, by a particularly high brightness. In the corresponding inverse experiments (inverse FRAP, inverse FLIP, inverse photoactivation), on the other hand, a particularly dark manipulation illumination is selected. Also known are methods in which the illumination during normal imaging and the manipulation illumination are distinguished from one another by their respective spectral compositions. The purpose of the manipulation illumination is to set in motion certain processes in the specimen being investigated; this can be, for example, bleaching or photoactivation of a fluorophore. Also conceivable is a reorganization within a fluorophore. These processes can result in changes in the spectral properties, or other detectable changes. By way of a locally differing selected manipulation illumination, local properties can be imparted to the specimen so that, for example, after manipulation illumination certain parts of cells have fluorophores that are visible particularly well or particularly poorly. The local properties imparted to the specimen can then be made visible in a confocal microscope. A redistribution of the fluorophores takes place as a result of transport processes in the interior of the specimen, for example inside cells. In many cases the transport processes ultimately result in a more or less homogeneous distribution of the fluorophores. The behavior over time of these processes can be made visible with the aid of microscopic images, allowing conclusions as to the transport processes in the specimen. Conventional experiments of the kind described above are generally carried out in such a way that the specimen is first scanned, once or repeatedly, with a laser light beam for the manipulation illumination. In a subsequent step, the specimen is then scanned for the actual image acquisition. The result obtained therefrom is a series of images at different time intervals. At a typical image acquisition rate, which is on the order of 1 to 100 frames per second, the time interval between two successive images is 10 ms to 1 second. It is extremely problematic in this context that diffusion processes in biological specimens generally proceed much more quickly. A fluorophore typically moves in a few microseconds out of the focus of a confocal microscope. Such snapshots consequently allow only extremely poor investigation of local properties of transport processes, for example local flow directions, barriers, etc., since a local excitation effected by the manipulation illumination propagates too greatly between two successive images. For image production, for example for color depiction of regions of the specimen having different transport properties, the known methods are, for the reasons described, quite entirely unsuitable. The so-called “volume effect” moreover causes additional problems for specimen investigation. The volume effect becomes apparent by the fact that transport processes also take place physically out of and into the image plane of a confocal microscope. Because the regions of the specimen located outside (i.e. above and below) the image plane are not accessible to observation, it is extremely difficult to interpret measured diffusion constants or other local conditions. For example, a local transport barrier in the image plane is not visible if the transport process overcomes that barrier by bypassing it through the volume located above or below it. Signal quality is also negatively affected by the volume effect, since manipulated fluorophores migrate relatively quickly into the volume above and below the image plane that is inaccessible to observation. To circumvent the problems associated with the volume effect, measurements for the investigation of transport processes in specimens are often performed with the confocal microscope pinhole open. This degrades the resolution in the laser beam direction, and a projected image of the specimen, instead of a defined section of the specimen, is acquired. This allows better interpretation of the data that are obtained, but at the same time the essential advantages of a confocal microscope—such as high resolution, flare suppression, etc.—must be sacrificed. It is now the object of the present invention to describe a method for investigating transport processes of the kind cited initially with which, in particular, processes within the specimen that proceed on a short time scale can also be investigated with high accuracy. The method according to the present invention for investigating transport processes achieves the aforesaid object by way of the features of claim 1. According to the latter, such a method is characterized in that both an image production light beam for the purpose of observing the specimen and a manipulation light beam for the purpose of manipulating the specimen are used as the laser light beam, the image production light beam preceding the manipulation light beam in such a way that pixels of the specimen not yet manipulated by the manipulation light beam are illuminated with the image production light beam. What has been recognized according to the present invention is firstly that the image acquisition rate of methods in which the specimen is scanned first with the manipulation illumination, and in a subsequent step for actual image acquisition, is too low for satisfactorily accurate investigation of transport processes that proceed rapidly, especially in biological specimens. The present invention proposes that definable regions of the specimen be illuminated by a laser light beam first for the purpose of observing the specimen and then for the purpose of manipulating the specimen. The consequence of the method according to the present invention is that only regions of the specimen that have not yet been exposed to any manipulation illumination are observed. The invention makes use, in this context, of the effect that after the manipulation illumination of definable specimen regions, transport processes take place which result, for example, in the transport of fluorophores into adjacent pixels. These can be sensed by the image production light beam, for example in the next line. Image production thus follows the manipulation illumination at an extremely short time interval, with the result that even rapidly proceeding transport processes are made accessible to observation. Advantageously, each line of the specimen is swept twice by the laser light beam, the first illumination serving for image production and the second illumination for manipulation of the specimen. Once the manipulation light beam has influenced the specimen pixels swept by it, fluorophores are transported into adjacent pixels as a result of transport processes. Those fluorophores that are transported into the next image line that is imaged are then sensed by the image production light beam in the next line, and become visible in the image. This yields an image in which the only fluorophores visible are those that were transported in the direction of the next image line as a result of a transport process. If a Cartesian coordinate system is defined in which the specimen is scanned, for example, in the positive X direction, the measured image brightness then constitutes a direct indication of the local transport flow in the Y direction. According to an alternative embodiment, each line of the specimen is swept by the laser light beam only once, the lines being used alternately for observation purposes and for manipulation purposes. In the interest of simple evaluation of and a high information content in the acquired images, a fixed correlation in time between the image production illumination and the manipulation illumination of the specimen proves advantageous. In the context of a further embodiment, provision is made for a separate laser light beam to be used respectively for image production and for manipulation of the specimen. In other words, a second laser light beam is used in addition to the laser light beam usually used for image production, and the two laser light beams can exhibit a fixed angle difference with respect to one another. This results in two illumination points at different locations on the specimen, which points possess a fixed physical distance from one another and scan the specimen synchronously with one another. The result of a fixed angle difference, whose magnitude can be defined in each case as a function of the specific application and the specific specimen properties, is that there is always a fixed distance in time between the image production light beam and the manipulation light beam of the previous line. In particularly advantageous fashion, the investigation is carried out by means of a confocal microscope. Because the image is generated almost immediately after manipulation, and volume processes consequently play a subordinate role, all the advantages of the confocal microscope can be utilized. In particular, it is not necessary to perform the investigation with the confocal microscope pinhole open; in other words, it is possible to work with a high resolution in the laser beam direction in order to achieve highly accurate image production. In the interest of a high degree of flexibility, provision can be made for the speed of the scanning apparatus to be adapted to the speed of the transport processes being investigated. The investigation can thereby be adapted to specimens having different properties and to different experimental situations, so that the most comprehensive information possible can always be obtained about the transport processes taking place in the respective specimen. For efficient investigation, regions of particular interest in the specimen can be determined, and the manipulation illumination of the specimen can be confined to the regions of interest that are defined. During the scanning operation, for example in the X direction, which is also referred to as an X scanning operation, the lines of the specimen can be illuminated continuously for the purpose of manipulation. For certain applications, on the other hand, it may be advantageous to alternately illuminate and not illuminate regions within a line. Manipulation illumination in a checkerboard-like pattern is, in particular, conceivable. In the context of a more complex embodiment, provision can be made for a spectrally selective manipulation illumination of the specimen, so that different types of fluorophores in the specimen can be excited in controlled fashion. In the context of such an embodiment, it is additionally advantageous to design the detection apparatus in such a way that a spectrally sensitive detection of the light proceeding from the specimen is also possible. To allow the most comprehensive information possible to be gathered regarding the transport processes taking place in the specimen, it is advantageous to acquire multiple images of the specimen, the individual images being rotated with respect to one another through a definable angle. The rotation of the image for another image acquisition can be implemented, for example, by means of an image rotator or by suitable activation of the scanning apparatus. From the acquired images, the transport flow in the interior of the specimen can then easily be calculated, for example, by determining the projection of the flow onto a fixed X or Y axis relative to the specimen, by suitable differentiation of the intensity values of the individual images. An alternative possibility is only to acquire one set of three images, for example for rotations of 0°, 120°, and 240°. The desired information can easily be ascertained by way of suitable linear combinations of the images. Appropriate techniques, including the associated correction methods, are well known in the context of quadrature encoders, and need not be explained in detail at this juncture. In the interest of highly accurate measurement results, it is advantageous to apply suitable correction methods for the investigation. Both online corrections, in which the specimen is influenced during the measurement itself, and subsequent offline corrections, are possible. The correction methods used make it possible, for example, to take into account offsets, the enrichment of cells with photoactivated fluorophores over the course of the measurement sequence, or similar undesired effects. The data obtained can be presented in multifarious ways, depending on the particular specific situation. A visualization of the measured data via color codings, vector diagrams, contour line graphs, or the like is particularly advantageous. It is furthermore possible to plot boundary lines and/or boundary surfaces in the acquired images on the basis of the measured data. The respective flow through the boundaries could additionally be indicated quantitatively. A representational identification of flow sources and/or flow sinks is likewise conceivable. The above and other features of the invention including various novel details of construction and combinations of parts, and other advantages, will now be more particularly described with reference to the accompanying drawings and pointed out in the claims. It will be understood that the particular method and device embodying the invention are shown by way of illustration and not as a limitation of the invention. The principles and features of this invention may be employed in various and numerous embodiments without departing from the scope of the invention. FIG. 1, in which pixels 1 of a specimen are depicted in an X,Y coordinate system, schematically shows line-by-line scanning of the specimen with two laser light beams 2, 3, the one laser light beam 2 functioning as manipulation light beam 4 and the other laser light beam 3 as image production light beam 5. The two laser light beams 2, 3 are guided over the specimen along the positive X direction. When the end of a line is reached, the scanning operation is continued at the end of a line that follows in the Y scanning direction. As is clearly evident from FIG. 1, two illumination points, at different locations on the specimen, are generated by laser light beams 2, 3. The two illumination points, which are indicated by a thicker border, possess a fixed physical distance from one another and scan the specimen synchronously with one another. The physical distance between the two illumination points is achieved by way of a definable angle difference between manipulation light beam 4 and image production light beam 5. Because image production light beam 5 precedes manipulation light beam 4, image production light beam 5 always sees a specimen that is as yet uninfluenced by manipulation light beam 4. FIG. 2 schematically shows the same scanning operation as in FIG. 1, but at a more advanced point in time. Because the specimen has been influenced by manipulation light beam 4, transport processes take place in the pixels swept by manipulation light beam 4; among other effects, those processes cause fluorophores to be transported into adjacent pixels. This process is depicted schematically, with arrows, for one pixel in the line numbered 6. In the operation depicted in FIG. 2 in which the next line (numbered 7) is scanned, those fluorophores that were transported as a result of a transport process from a previous image line into the image line currently being imaged are now sensed by image production light beam 5 and thus made visible in the image. Because of the fixed angle difference between manipulation light beam 4 and image production light beam 5, in each line image production light beam 5 always has a fixed spacing in time from manipulation light beam 4 of the previous line which influenced the transported fluorophores. The method described can thus be used with particular advantage in conjunction with photoactivatable fluorophores. Utilization for FRAP, FLIP, or similar experiments is, however, additionally possible. FIG. 3 shows, once again schematically, acquired images that can be obtained with the method according to the present invention. FIG. 3a), firstly, depicts a possible transport flow within the specimen. What is depicted specifically is a transport process that proceeds counterclockwise around a center. While no transport processes take place at the center itself, the intensity of the transport processes increases with increasing distance from the center. The subsequent FIGS. 3b) to e) show the relevant acquired intensity images. FIG. 3b) shows an image that was obtained, as explained in conjunction with FIGS. 1 and 2, from a specimen scan in the positive X and positive Y direction. The bright left half of the image results from the strong transport flow in the positive Y direction in this region. The right half of the image, conversely, appears dark, since no transport flow in the positive Y direction is present in the corresponding specimen region. FIG. 3c) shows an image rotated 90° by means of an image rotator. The bright upper region of the image is attributable to the transport flow in the negative X direction present in this specimen region. FIG. 3d) shows an acquired image rotated 180°, which was obtained with a Y scan direction turned around as compared with the image shown in FIG. 3b). A high intensity exists here in the right part of the image, attributable to the transport flow in the negative Y direction present in the corresponding specimen region. Lastly, FIG. 3e) shows an acquired image rotated 270°. This image was acquired using a 90° image rotator and a Y scanning direction as in the image depicted in FIG. 3d). From the individual images, the transport flow in the interior of the specimen can easily be calculated, for example by determining the projection of the flow onto a fixed X or Y axis relative to the specimen by differentiating the intensity values in the 0° and 180° images and in the 90° and 270° images, respectively, thus yielding the relevant local vectors. Those vectors are depicted, as already explained above, in FIG. 3a). It is also possible in this fashion to detect local sinks and sources of the transport flow caused, inter alia, either by the production or annihilation of fluorophores or by transport into or out of the image plane. It may be noted that the method described need not necessarily be carried out in an image plane parallel to the specimen surface. Oblique sections through the specimen are likewise possible. Lastly, FIG. 4 schematically shows the scanning operation according to a further exemplifying embodiment of the method according to the present invention. Here manipulation light beam 4 is controlled in such a way that it alternately illuminates pixels 6 and exempts pixels 7 from illumination, the overall result being a manipulation illumination in the manner of a checkerboard. Apart from that, the reader is referred, in order to avoid repetition, to the statements made in conjunction with FIGS. 1 and 2. In conclusion, be it noted very particularly that the exemplifying embodiments discussed above serve merely to describe the teaching claimed, but do not limit it to the exemplifying embodiments. While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims. |
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060463740 | abstract | A method for forming a radiation-absorbing barrier around a radioactive component by flowing a radiation-absorbing cement grout into a container which encloses the component. The radiation-absorbing cement grout comprises a cement slurry, a finished foam material, a bentonite gel, and a radiation-absorbing metal constituent. |
description | This application is a divisional application of U.S. application Ser. No. 11/769,064, filed on Jun. 27, 2007, which is a divisional application of U.S. application Ser. No. 10/711,224, filed on Sep. 2, 2004, now U.S. Pat. No. 7,406,397, the contents of both applications are incorporated by reference herein in their entirety. 1. Field of the Invention The invention relates to semiconductor circuit design, and more particularly to modeling temperatures of a self-heating semiconductor device. 2. Background Description Accurate measurement of self-heating of SOI and SiGe based MOSFET devices is important because DC currents of such devices are typically depressed significantly due to self-heating. This is in contrast to CMOS circuits where transients are too rapid for significant self-heating to occur. Thus, simulation (compact) models must be adjusted to correctly account for self-heating in order to correctly predict circuit performance. In SOI technologies, this effect ranges from about 3 percent to 12 percent, while in SGOI (SiGe on SOI) these effects are expected to exceed 30 percent. Such large temperature effects in SGOI devices are due in part to the active region of the device being almost entirely surrounded by layers of material having poor thermal conductivity properties. For example, the active region of the SGOI device is SiGe, and the SiGe is arranged on top of an oxide layer. The SiGe layer has a limited length and width on top of the oxide layer, and thus forms what is referred to as a “island” on the oxide layer. During subsequent fabrication steps, the SiGe island is surrounded on its sides by an oxide, and then further covered over its top by an oxide. Thus, the SiGe island is relatively small and almost entirely surrounded by an oxide. Due to the surrounding oxide, the SiGe island has extremely limited thermal pathways by which to dissipate any heat generated in the SiGe island. The small dimensions of the SiGe island also increase the device's susceptibility to thermal effects. In particular, because the SiGe island is relatively small, it has a comparatively low thermal mass. With the low thermal mass, the SiGe island quickly responds to any heating by a device thereon. As such, the SiGe island itself fails to act as its own heat sink for the device and the device quickly heats the island up to the devices own temperature. Thus, any device fabricated on the SiGe island will be particularly influenced by its own self-heating effects. Known methods of measuring semiconductor device performance versus temperature include placing a diode proximate to the device for which the temperature will be measured, and using the diode's change in electrical performance as a function of temperature to measure the temperature at that point. However, such a method is difficult to implement because it is difficult to build such a diode close to a device to be measured to provide an accurate gauge of the active region of the device. Another method of measuring the temperature effect on the electrical characteristics of a semiconductor device includes running the device at a particular power level to heat itself, and using the device's own change in electrical characteristics as a function of temperature to determine the temperature of the device. While simple to fabricate such a temperature measurement configuration, the data produced by such a configuration is less than reliable because of various hysteresis-like effects. For example, the device's sensitivity to temperature changes, may be based on, for example, among other things, on the prior electrical history of the device. Such a sensitivity to electrical history makes determining the actual temperature of the device to be less than reliable. The invention is designed to solve one or more of the above-mentioned problems. In a first aspect of the invention, a method of measuring performance of a device includes thermally coupling a first heating device to a first sensing device, and generating heat at the first heating device. The method also includes measuring a change in at least one electrical characteristic of the first sensing device caused by the heat generated at the first heating device, and calculating a temperature of the first heating device using the measured change in the at least one electrical characteristic. In another aspect of the invention, a method of measuring performance of a device, includes thermally coupling a heating transistor to a measurement transistor at one or more predetermined distance, and calibrating the measurement transistor by measuring a particular electrical characteristic of an active region of the measurement transistor with the measurement transitory held at a known temperature. The method also includes generating heat at the heating transistor, and incrementally measuring a change in the at least one electrical characteristic of the measurement transistor caused by the heat generated at the heating transistor. The method additionally includes calculating a temperature of the heating transistor using the measured change in the at least one electrical characteristic. In another aspect of the invention, an apparatus for measuring semiconductor device temperature, includes a silicon island, and at least one pair of transistors, each pair of the at least one pair of transistors comprises a transistor configured to generate heat and a transistor configured to sense temperature, wherein each transistor of each pair of transistors is arranged a prescribed distance from its corresponding transistor. In another aspect of the invention, an apparatus for measuring semiconductor device temperature, includes at least one silicon island, and at least one heating field effect transistor configurable to generate heat arranged within the silicon island. The apparatus also includes at least one sensing field effect transistor arranged within the at least one silicon island corresponding to each heating field effect transistor of the at least one heating field effect transistor, wherein each sensing field effect transistor is arranged a prescribed distance from its corresponding heating field effect transistor and each sensing field effect transistor is configurable to sense a temperature. The apparatus additionally includes means to calculate a temperature of the each heating field effect transistor using a measured change in at least one electrical characteristic of the each sensing field effect transistor caused by the heat generated at the each heating field effect transistor. In another aspect of the invention, an apparatus for determining the temperature of an active region of a semiconductor device includes three silicon sections, and three pairs of active regions, wherein each pair of active regions is arranged on a respective silicon section, wherein each pair of active regions is configurable to produce and sense heat. The apparatus also includes three thermal conductors, wherein each thermal conductor is arranged between each active region of each respective pair of active regions. In another aspect of the invention, a computer program product comprising a computer usable medium having readable program code embodied in the medium, the computer program product includes at least one component to measure a change in at least one electrical characteristic of a first sensing device caused by heat generated at a first heating device, and calculate a temperature of the first heating device using the measured change in the at least one electrical characteristic. The invention is directed to determining the temperature of an active region of a device fabricated using SGOI technology as a function of electrical power through the device. Such information may be used to characterize the effect of temperature on the performance characteristics of the device. This information may be utilized by design engineers to predict device performance during the circuit layout process, as a function of temperature, and to accommodate such temperature effects in the circuit design. To reliably measure the temperature of a semiconductor device, and thereby determine the effects on performance of the device, a method includes fabricating two devices in thermal communication with one another, where the first device is run at a predetermined power level, and the second device is a prescribed distance from the first device. The second device, otherwise known as the measuring device, is capable of providing temperature information at its position as a function of the first device, e.g., power level of the heating device. In operation, a particular electrical characteristic of the second device is monitored to determine the temperature of the second device. This characteristic may be, for example, the sub-threshold voltage slope (also referred to as “Sub Vt”) as shown in FIG. 1. In this embodiment, multiple devices are used at varying distances from the heating device to make various temperature measurements at varying distances. The measurements are used to calculate the temperature of the active region of the heating device by extrapolating the distanced-based temperature measurements back to the origin, i.e., the position of heating device. In one embodiment, the fabricated device may include multiple SiGe islands which are fabricated where each SiGe island has its own measurement and heating device pair. For example, two FETs may be fabricated on a SiGe island a prescribed distance apart. After fabrication, a particular electrical characteristic of the second FET is measured at multiple ambient temperatures. The power levels and distances as well as other measurable phenomena and features are shown for illustration purposes in FIGS. 1 and 2 as well as the exemplary data and results shown in Tables 1-5. The method is illustrated in more detail in FIGS. 9 and 10 as discussed below. By carrying out the measurement process for each measurement/heating device pair, the temperature and power information can be used to calculate the temperature of the active device. Although the measurement device typically has multiple electrical characteristics which will vary as a function of its temperature, an embodiment of the invention uses a sub-threshold voltage slope as a function of temperature to measure temperature. Referring to FIG. 1, a graph showing sub-threshold voltage slope versus power at 25° C. ambient temperature is shown. The y-axis represents channel current of the measurement device, and the x-axis represents various voltages as the source input voltage is varied, where the two gates and the two drains of the devices are common to one another making Vgs (voltage between the gate and source) equal to Vds (voltage between the drain and source). Accordingly, Vgs=Vds as noted on the x-axis of FIG. 1. The common diffusion input and the measurement source may be connected with Kelvin connectors. The information of FIG. 1 is an example of an electrical characteristic of the sensing device from which its temperature is inferred. This information may be used in the method of the invention as described herein. The data for each power point is a voltage ramp of the measurement source from, for example, Vgs=Vds=1.0 V to Vgs=Vds=0.6 in 0.010V increments. The sub-threshold voltage slope is fit below Vt and above the point where the behavior deviates from log-linear. For typical devices, Vgs=Vds=0.1 v to 0.2 v was used. For reference, the single point Vt is 11.25 .mu.A for a device. It should be noted that similar plots are typically constructed and the slope calculated for a device at 50° C., 75° C., and 100° C. with no power in the heating device. From these plots, the relationship between sub-threshold voltage slope and temperature of the measurement device may be determined. The temperature of the measurement device can be determined by comparing the sub-threshold voltage slope at a given heating device power to the relationship features sub-threshold slope and temperature previously determined with no power to the heating device. Referring to FIG. 2, a change in temperature versus power of a self-heating semiconductor device is shown. The graph of FIG. 2 is an example of the graphs generated for each measurement and heating device pair at various distances. Thus, the measurement with heating devices for FIG. 2 is illustrative examples, and should not be considered a limiting feature. Other examples are contemplated and can be easily determined by those of skill in the art in view of the present invention. This illustrative information of FIG. 2 is the final result after extrapolation and all measurements and calculating steps resulting from the flow of the invention as described in more detail with reference to FIGS. 9 and 10. In the graph, the y-axis represents the change in temperature in degrees centigrade, and the x-axis represents the power applied to the device in micro Watts (μW) at 25° C. ambient temperature. The line on the graph was derived for heating bias conditions of Vgs=Vds=0V to 1V in 0.1V increments. These slopes were converted to temperature changes and plotted versus the applied power. FIGS. 3 through 7 illustrate steps in fabricating an embodiment of the self-heating monitor. Referring to FIG. 3, an SOI wafer is shown. The SOI wafer includes a silicon substrate 12 overlaid by a thin, buried oxide layer 14. On top of the buried oxide layer 14 is arranged a layer of silicon 16. The buried oxide layer 14 and silicon layer 16 may be formed on a silicon substrate 12 by any of the methods well-known in the art, such as, for example, a high-energy oxygen implant and then activating the oxygen to form the buried oxide layer 14. Referring to FIG. 4, well-known standard photo lithographic imaging and etching techniques are preformed to remove portions of the silicon layer 14 to form a silicon island 18 on top of the buried oxide layer 14. Next, shallow trench isolation oxides 20 are formed surrounding the edges of the silicon island 18. The oxide is deposited into the regions surrounding the edge of the silicon island 18 by any of the oxide deposition techniques well-known in the art. The silicon island 18 is then implanted with a well doping ion (P-type for N-channel devices, and n-type for P-channel devices) using any of the doping techniques well known in the art. In the example shown in FIG. 4, the channel regions of the two devices being fabricated are doped with P-type dopant. Referring to FIG. 5, the surface of the silicon island 18 is cleaned and a gate oxide 22 is formed on the surface of the island 18. The gate oxide 22 can be formed by any of the methods for depositing, imaging and etching gate oxides well known in the art. A gate polysilicon layer 24 is formed on top of the gate oxide 22, and patterned and etched to form the device gate structure using any of the methods well known in the art to fabricate gate polysilicon layers. After the gate polysilicon 24 is formed, spacers 26 are formed on top of the gate oxides 22 and abutting the edges of the gate polysilicon 24. The spacers 26 can be formed from materials and using methods well known in the art and include, for example, nitride or oxide spacers. After the spacers 26 are formed, the region of the silicon island 18 not covered by the gate structures is implanted 19 with the appropriate dopant relative to the channel dopant. In this example, the channels are doped with p-type ions, and thus the regions in the silicon island 18 to either side of the gate structures is doped with n-type ions, as well as doping the gate polysilicon 24. Doping techniques which may be used for this step are well known in the art. In this example, the n-doped regions form the source and drain regions 28, and the p-doped region forms the channel 30 of the measurement and heating device pair The dopant types, concentrations and energy levels would be those appropriate for whichever type of device is being fabricated, and are well-known in the art. Referring to FIG. 6, the silicide layer 32 is formed over the source and drain regions, 28, and the gate-polysilicon 24. After the silicide layer 32 is formed, a planar oxide layer 34 is deposited over the shallow trench oxide regions 20, silicide 32 and gate structures. The planar oxide 34 can be deposited using any of the methods well-known in the art. Referring to FIG. 7, vias 35 are patterned and etched in the planar oxide 34 from a top surface of the planar oxide 34 down to the silicon island 18. The vias 35 are filled with conductive material, such as metal to form contacts 36 to the source and drain regions 28 of the silicon island 18. After the contacts 36 are formed, a first metal wiring layer 38 is deposited on top of the planar oxide 34. The first metal wiring layer is then etched to form metal contacts 38 on a top surface of the planar oxide 34, in electrical contact with the contacts 36. Referring to FIG. 8, a top view of an embodiment of the device 50 is shown, illustrating various metal contacts to the devices on silicon island 52. The silicon island 52 has a heating device drain metal contact 60, and a measurement device drain contact 62. Also included on the silicon island 52 is a common source contact 54 which leads to the source of both the underlying measurement device and the heating devices. A measurement gate contact 56 and a heating gate 58 are also included on the silicon island 52. It should be noted that although a particular example of forming the heating and measuring devices is discussed above, any fabrication process which produces a pair of semiconductor devices such as FETs in thermal communication with one another may be suitable for the temperature measurement. As such, the temperature measurement method can work with any pair of devices where one of the devices produces heat, and the other device responds to that heat in some measurable way, such as one of its electrical characteristics changing in accordance with its temperature. It should also be noted that while the examples discussed above use two devices of similar design for heating and measuring, the measurement device and the heating device may be of completely different designs as long as the heating device is capable of heating and the measurement device is capable of measuring temperature and the two are in thermal contact. Additionally, two devices may be in thermal contact with one another without actually being in physical contact with one another. Thus, two devices may be in thermal contact while actually touching one another, and two devices may be in thermal contact where the thermal contact is through an intermediate thermal conductor such as a length of silicon in physical contact with one another. It should be noted that the silicon island may have a perimeter which describes a square as well as other geometric shapes such as rectangles, circles, oblongs, triangle, etc. Additionally, although the measurement device in FIGS. 3-7 show two FETs, the measurement device can be made with more FETs. In general, the measurement method relies upon two semiconductor devices where one device functions as a heat source, and the other devices functions as a temperature measurement. For example, the temperature measurement method may rely on two FETs fabricated on a single silicon island, which is substantially surrounded on all sides by material having low thermal conductivity as discussed below. One of the FETs is referred to as the heating device, and generates heat when it is powered up. The second device is referred to as the measurement device, and measures the temperature in its active region by sensing a change in a prescribed electrical characteristic of its active region, which is then correlated to temperature. In implementation, the distance between the heating device and the measurement device is varied and thus the temperature at the heating device may be extrapolated from multiple measurements. To determine the correspondence between power applied to the heating device and its temperature, a series of measurements for each heating/measurement pair is performed where varying amounts of power are applied to the heating device and the temperature at the measurement device is determined. This process may be repeated for the multiple pairs of heating/measurement devices where each pair has a different distance between the heating and measurement device. By measuring the temperature at varying distances from the heating device, the data can be extrapolated and the temperature of the active region of the heating device under various amounts of power can be determined. Typical distances between the heating device and the measurement device range from ¼ of a micron to one or two microns. It should be realized that due to the thermal characteristics of the silicon island, multiple measurements using different pairs of heating and measurement devices in different geometries may be required to accurately determine the relationship between power applied to the heating device and its temperature. For example, multiple pairs of heating and measurement devices may be made where each measurement device corresponds to a particular heating device and with a different separation distance. Before actual measurements can be made, the measurement device of each heating/measurement pair should be calibrated. The calibration of the measurement device is performed by measuring a particular electrical characteristic of the active region of the measurement device with the measurement device held at a known ambient temperature. For example, the measurement device can be held at 25° C. and the sub-threshold voltage slope is measured in a range from 0-0.4 volts driving voltage of the heating device. The sub-threshold voltage slope may be measured by holding the gate voltage at 0 and sweeping the drain through the desired voltage range. Next, 0.1V is applied to the drain of the heating device and another sweep of the drain of the measurement device is done. This process maybe repeated in 0.1 V steps of the drain of the heating device until the entire desired range is swept through. Other voltage steps are also contemplated. The collected data produces a sub-threshold voltage slope at each different increment of power corresponding to the voltage applied to the drain of the heating device as illustrated by the example of FIG. 1. Additionally, the current of the heating device is measured so that the power being dissipated by the device is known. Such a process is repeated for multiple temperatures and a sub-threshold voltage slope versus temperature relationship is derived. For example, the process is repeated for 15° C., 75° C. and 100° C. temperature points. Accordingly, four sub-threshold voltage slopes as a function of ambient temperature are determined with no self-heating at the heating device to calibrate the measurement device. For the typical geometry of heating/measurement device, there may be thermal effects which would not be present during operation of the heating device in an actual application as distinguished from having its temperature measured. For example, the presence of a measurement device may require metal contacts which otherwise would not normally be there. Such metal contacts may act as heat sinks which conduct heat away from the heating device, thereby effectively reducing the temperature below that at which it would normally operate. This thermal effect can be understood and accounted for by fabricating the heating/measurement device pairs so that such thermal effects are the same from pair to pair. Accordingly, it is advantageous to make the thermal resistance between the devices for each pair of devices as similar as possible. Referring to FIG. 9, a flow chart of an embodiment of the measurement method is shown. FIGS. 9 and 10 may equally represent a high-level block diagram of components of the invention implementing the steps thereof. Several of the steps of FIGS. 9 and 10 may be implemented on computer program code in combination with the appropriate hardware. This computer program code may be stored on storage media such as a diskette, hard disk, CD-ROM, DVD-ROM or tape, as well as a memory storage device or collection of memory storage devices such as read-only memory (ROM) or random access memory (RAM). Additionally, the computer program code can be transferred to a workstation over the Internet or some other type of network. In step S10, a sensing device of a device pair having a sensing device and a heating device is calibrated. The calibration may include of determining the variation of a particular electrical characteristic of the sensing device as a function of temperature. In step S 20, the calibration process S10 is repeated for a different distance between the sensing and heating device. This typically involves a different device pair arranged at a distance different from the previously calibrated device pair. In S30 of FIG. 9, a temperature measurement is processed for a device pair at a particular distance. The temperature measurement typically involves running the heating device at various power levels. In S40, the temperature measurement is performed at a different distance for a device pair, and typically involves a different device pair arranged at a distance different from the previously measured device pair. S50 includes calculating a temperature versus power level relationship for the heating device using the data collected at different power levels and different distances between the sensing and heating devices. Referring to FIG. 10, an example of an embodiment of the measurement method is shown. In S100, a sensing device of a first device pair having a sensing and a heating device is calibrated for a chosen separation distance. The calibration process includes monitoring a particular electrical characteristic of the sensing device while the device pair is held at a selected ambient temperature with no power being applied to the heating device. For example the sub-threshold voltage slope of the sensing device may be monitored while the device pair is held at 25° C. In S120, the calibration process is repeated while the device pair is held at a second ambient temperature, such as, for example, 50° C. In S140, the calibration process is repeated at a third temperature, such as, for example 100° C. A relationship between the temperature of the device and the chosen electrical characteristic is then calculated by fitting the data to a curve, such as by a least squares method. Alternatively, the data may be fitted to a curve using any of the curve fitting software packages which are well known in the art In S160, the calibration process is checked to determine whether the process had been performed for each selected distance. If device pairs are to be calibrated at other distances, the calibration process is repeated at S180 for all the chosen temperatures at a different distance between a sensing and heating device. This typically involves a new device pair having of a similar sensing and heating device as in the previous device pair, but arranged with a different separation distance. After the calibration steps, S100, S120, S140, S160 and S180 are complete, a measurement is made in S200 at a first power level for the heating device and a first distance separating the device pair. The measurement is repeated for a second and third power level in steps S220 and S240, respectively. When all the predetermined power levels have been measured, the process is repeated in S260 and S280 if other distances are to be measured. Once all measurement data has been collected in steps S200, S220, S240, S260 and S280, a relationship between temperature and power of the heating device is calculated using, for example, any of the commercially available curve fitting software packages capable of fitting data to a curve. The relationship between the temperature and power of the heating device is typically an exponential relationship, although other relationships are possible and can be accommodated by the method. Table 1 shows examples of dimensions of various devices which were fabricated for measurements of temperature using the above-described method. As can be seen from Table 1, silicon islands of various lengths and widths were used as well as gate spacings between the gates of the heating and measurement device. The devices also had various numbers of contacts, ranging from 2 to 4 to 6. Additionally, the comments section includes information about the device geometry such as gate spacing and length. TABLE 1GateRxLdWdSpacingLengthDevice(μm)(μm)(μm)(μm)ContactsCommentsM1S10.875.12250.26250.89252/3XVery narrowRxM1S20.8751.750.981.614/4XWide spacebetween gateswithout AlbridgeM1S30.8751.750.50751.13754/4XMediumspace betweengates with AlbridgeM1S40.8751.750.26250.89254/3XBase deviceM2S10.8750.8750.26250.89252/3XNarrow RxM2S30.8751.750.26250.89256/3XExtra contacts& cooling finsM2S40.8751.750.262535.93514/3XVery long RxM3S10.8751.750.26252.64254/3XMedium longRxThe various device geometries are labeled, for example, M1S1. Thus, various device geometries were tested. Table 2 shows the heating effects for three different gate spacings of 0.26 micron, 0.51 micron and 0.98 micron. The column labeled Waf T5TY and at Waf Q878 each represent different SOI wafers from which the respective measurement devices were manufactured. For example, the device type M1S4 was manufactured on two different wafers, the first labeled T5TY, and the second labeled Q878. TABLE 2Waf T5TYWaf Q878PC spacingDeg C./mW/uDeg C./mW/uCommentsBase device,33.2536.75M1S4-4CA/3XPC-PC = 0.26PC-PC = 0.5118.819.1M1S3-4CA/4X,A1 bridgePC-PC = 0.985.57.9M1S2-4CA/4X,No A1 bridge Referring to Table 3, the results of adding contacts is shown to the device M1S4 and the device M2S3. TABLE 3Waf T5TYWaf Q878Added CADeg C./mW/uDeg C./mW/uCommentsBase device,33.2536.75M1S44CA/3X6CA/3X &26.2531.5M2S3“cooling fins” Referring to Table 4, devices of different widths are shown and the results thereto. TABLE 4Waf T5TYWaf Q878Device widths/Ca/uDeg C./mW/uDeg C./mW/uCommentsBase device,33.2536.75M1S44CA/3X, W = 1.752CA/3X, W = 0.82528.530.3M2S12CA/3X, W = 0.12253.10.8M1S1 Referring to Table 5, the results of various RX paths of the device are shown for the devices M1S4, M3S1 and M2S4. TABLE 5Waf T5TYWaf Q878RX past deviceDeg C./mW/uDeg C./mW/uCommentsBase device,33.2536.75M1S4RX = 0.89RX = 2.6433.2526.3M3S1RX = 35.930.9N/AM2S4 In the embodiments described above, the heat reducing effects of the contacts between the gates was considered negligible. However, to more accurately determine the self heating, the embodiments of FIGS. 11-13 take into account the thermal resistance of the contacts in order to more accurately assess the self heating. As should be understood, the contacts create a thermal resistance. That is, the contacts act as heat sinks which take heat away from the silicon island 52 which, in turn, reduces the temperature at the measurement gate contact 56. Accordingly, without taking into account the number of contacts, the reading of the temperature may vary by a certain offset, equal with a proportionality to the number of contacts. But, to compensate for this offset, the technique of FIGS. 11-13 use a measurement differential taken with at least two devices having a different number of contacts and extrapolating the results to zero contacts. In embodiments, this is accomplished by adding or subtracting the number of contacts between two or more different devices, as discussed below. The measuring technique associated with FIGS. 11-13 is applicable to both wide and narrow type devices, known in the art. In the measuring technique of this aspect of the invention, the number of contacts will vary on the diffusion between the measurement gate contacts 56 and heating gate contacts 58 of different measured devices to establish the rate of temperature change per contact. Once the rate of temperature change is established for the devices, it is then possible to extrapolate that change to zero contacts to determine the actual device temperature without the effect of the offsetting contacts between the gates. By way of example, FIGS. 11 and 12 represent a top view of a wide device 50. Similar to the previous embodiments, in FIGS. 11 and 12, the silicon island 52 has a heating device drain metal contact 60 and a measurement device drain contact 62. Also provided on the silicon island 52 is a common source drain contact 54 which leads to the source drain of both the underlying measurement device and the heating device. A measurement gate source contact 56 and a heating gate source 58 are further provided on the silicon island 52. FIG. 11 shows 12 contacts on the common drain 61; whereas, FIG. 12 shows six contacts. The different number of contacts between FIGS. 11 and 12 provides for a measured temperature differential in accordance with this aspect of the invention. It should be understood that any number of contacts may be used with the extrapolative method of this embodiment by either adding or subtracting contacts. By illustrative example, in the embodiment of a wide device such as shown in FIGS. 11 and 12, it is preferable to subtract contacts. Thus, FIG. 11 includes 12 contacts and FIG. 12 shows six contacts. However, in narrow devices such as shown in FIG. 13, it is preferable to add contacts. Thus, in the narrow device example, it may be necessary to add an additional contact 61A to reduce the thermal resistance which, in turn, results in a measured heat differential (e.g., difference of the thermal load) between a first narrow device with one contact and a second narrow device with two contacts. Once these temperature differentials are measured, the results are then extrapolated to zero contacts, in any well known extrapolative technique. In one aspect of the invention, for a wide device the procedure should be applied to the smallest gate spacing, since the measurement temperatures (signal) is highest and the effect will be largest. The number of contacts is then reduced to allow the slope of the measured temperature to be determined versus the number of contacts. To help calibrate the narrow device the total number of contacts is kept the same as a case where all the contacts are an equal distance from the gate edge to help further quantify the results for one case. Additional cases with fewer contacts could also be added to further determine the proper scaling. While the invention has been described in terms of embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the appended claims. For example, the invention can be readily applicable to multiple measurement devices associated with the single heating device. |
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claims | 1. A nuclear fuel rod comprising:a container including:a support material defining an exterior facing surface having a roughness Ra in a range of 10 nm to 500 nm, wherein the support material includes zirconium, tin, niobium, iron, chromium, nickel, hafnium, alloys thereof, or a combination thereof;a rough material layer disposed over the exterior facing surface of the support material, the rough material layer comprising yttria-stabilized zirconia, wherein the roughness Ra of the rough material layer is in a range of 10 nm to 1 micrometer; anda ceramic nitride layer disposed over and in direct contact with the rough material layer, the ceramic nitride layer including silicon nitride, the ceramic nitride layer having a roughness Ra of at least 0.1% and not greater than 50% of the roughness Ra of the rough material layer; anda nuclear fuel disposed within the container. 2. The nuclear fuel rod of claim 1, wherein the rough material layer includes a crystalline material. 3. The nuclear fuel rod of claim 1, wherein the rough material layer has a thickness in a range of 50 nm to 5 micrometers. 4. The nuclear fuel rod of claim 3, wherein the rough material layer has a thickness in a range of 50 nm to 1 micrometer. 5. The nuclear fuel rod of claim 1, wherein the ceramic nitride is an enriched ceramic nitride, wherein the enriched ceramic nitride includes 2% to 20% 15N. 6. The nuclear fuel rod of claim 1, wherein the roughness Ra of the rough material layer is in a range of 50 nm to 500 nm. 7. The nuclear fuel rod of claim 1, wherein the support material is a zirconium alloy. 8. The nuclear fuel rod of claim 1, wherein the ceramic nitride is an enriched ceramic nitride, wherein the enriched ceramic nitride includes 80% to 99.99% 15N. 9. The nuclear fuel rod of claim 1, wherein the roughness Ra of the rough material layer is in a range of 50 nm to 1 micrometer. 10. The nuclear fuel rod of claim 1, wherein the roughness Ra of the rough material layer is greater than the roughness Ra of the exterior facing surface of the support material. 11. The nuclear fuel rod of claim 1, wherein the roughness Ra of the ceramic nitride layer is not greater than 40% of the roughness Ra of the rough material layer. 12. The nuclear fuel rod of claim 11, wherein the roughness Ra of the ceramic nitride layer is not greater than 30% of the roughness Ra of the rough material layer. 13. The nuclear fuel rod of claim 12, wherein the roughness Ra of the ceramic nitride layer is not greater than 25% of the roughness Ra of the rough material layer. 14. The nuclear fuel rod of claim 1, wherein the ceramic nitride layer is amorphous. 15. The nuclear fuel rod of claim 1, wherein the ceramic nitride layer is crystalline. 16. The nuclear fuel rod of claim 1, wherein the ceramic nitride layer has a thickness in a range of 50 nm to 10 micrometers. 17. The nuclear fuel rod of claim 16, wherein the ceramic nitride layer has a thickness in a range of 50 nm to 1 micrometer. |
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047643331 | summary | The present invention concerns end closures for containers, in particular end closures for nuclear fuel transport flasks. BACKGROUND OF THE INVENTION One form of flask for the transport of nuclear fuel comprises a vessel having a removable closure member at one end. The flask accommodates a bottle or magazine containing the fuel and the flask is emptied by setting in an upright position with the removable closure member at its lower end whereby upon removal of the closure member the bottle or magazine can be lowered out of the flask. As the fuel within the bottle or magazine is submerged in water which can leak out of the bottle it is necessary as a safety feature to ensure that the end closure member effect a liquid tight seal at the end of the flask. It has been proposed to utilise a wedge-shaped member to effect a seal whereby lateral movement of the wedge-shaped member across the end of the flask causes an initial vertical displacement of the end closure member to break the seal at the end of the flask. This has the advantage of reducing damage to the seal by a tearing action which could arise if the closure member was moved laterally across the end of the flask seal face without any initial separation. However the use of a single wedge-shaped member results in an end closure member of a non-uniform thickness. FEATURES AND ASPECTS OF THE INVENTION According to the present invention there is provided an end closure for a container, in particular an end closure for a nuclear fuel transport flask, comprising a gate movable between open and closed positions across an end of the flask, the gate having first and second portions continuously urged apart, a door releasably mounted on the gate and sealingly engageable with an opening in the end of the flask, the door having upper and lower cooperable wedge-shaped members releasably mounted on the first and second gate portions respectively for movement therewith between the open and closed positions, the assembly being arranged such that a lateral displacement of the gate into or out of its fully closed position effects movement of the second gate portion only and corresponding movement of the associated lower wedge-shaped door member, with the first gate portion and its associated upper wedge-shaped door member remaining stationary whereby to effect a vertical displacement of the upper wedge-shaped door member into or out of sealing engagement with the opening in the end of the fuel flask. |
summary | ||
abstract | A radiation exposure system having a beam source is provided. The system further includes a variable thickness degrader, positioned between the beam source and an object to be exposed, for providing varying degrees of degradation to a radiation beam emitted from the beam source onto the object. The system also includes a set of detectors, positioned between the variable thickness degrader and the object, for receiving and measuring only a portion of the radiation beam remaining after the degradation of the radiation beam by the variable thickness degrader. |
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042004926 | claims | 1. A nuclear fuel element which comprises an elongated composite cladding container having a zirconium alloy tube containing constituents other than zirconium in an amount greater than about 5000 parts per million and a barrier of sponge zirconium metallurgically bonded to the inside surface of the alloy tube, said sponge zirconium barrier being of thickness from about 1% to 30% of the thickness of the said alloy tube, a central core of a body of nuclear fuel material selected from the group consisting of compounds of uranium, plutonium, thorium and mixtures thereof disposed in and partially filling said container so as to leave a gap between said container and said core and an internal cavity at one end of the container an enclosure integrally secured and sealed at each end of said container and a nuclear fuel material retaining means positioned in the cavity. 2. The nuclear fuel element of claim 1 which has in addition a cavity inside the fuel element and a nuclear fuel material retaining means comprising a helical member positioned in the cavity. 3. A nuclear fuel element of claim 1 in which the nuclear fuel material is comprised of plutonium compounds. 4. A nuclear fuel element of claim 1 in which the nuclear fuel material is comprised of uranium dioxide. 5. A nuclear fuel element of claim 1 in which the nuclear fuel material is a mixture comprising uranium dioxide and plutonium dioxide. |
claims | 1. A nuclear power system, comprising:a reactor vessel that comprises a reactor core mounted within a volume of the reactor vessel, wherein the reactor core comprises one or more nuclear fuel assemblies configured to generate a nuclear fission reaction, and wherein the reactor vessel does not include any control rod assemblies therein;a riser positioned above the reactor core;a primary coolant flow path that extends from a bottom portion of the volume below the reactor core, through the reactor core, within the riser, and through an annulus between the riser and the reactor vessel back to the bottom portion of the volume;a primary coolant that circulates through the primary coolant flow path to receive heat from the nuclear fission reaction and release the received heat to generate electric power in a power generation system coupled to the primary coolant flow path;a chemical injection system in fluid communication with the primary coolant flow path; anda control system communicably coupled to the power generation system and the chemical injection system, wherein the control system is configured to control a power output of the nuclear fission reaction independent of any control rod assemblies by controlling one or more parameters of at least one of the power generation system or the chemical injection system, and wherein the control system is configured to perform operations to control one or more parameters of the chemical injection system, the operations comprising:determining that the power output of the nuclear fission reaction is greater than an upper value or less than a lower value;based on the determination, adjusting an amount of a chemical injected into the reactor core from the chemical injection system to adjust the power output of the nuclear fission reaction; andsubsequent to the adjustment, determining that the power output is within a range. 2. The nuclear power system of claim 1, wherein the control system is further configured to perform operations to control one or more parameters of the power generation system comprising:based on the determination, controlling the power generation system to adjust at least one of a turbine inlet steam valve or a feed water pump to adjust the power output of the nuclear fission reaction. 3. The nuclear power system of claim 2, wherein the operation of controlling the power generation system to adjust the turbine inlet steam valve comprises at least one of:adjusting the turbine inlet steam valve toward a fully closed position to decrease the power output of the nuclear fission reaction; oradjusting the turbine inlet steam valve toward a fully open position to increase the power output of the nuclear fission reaction. 4. The nuclear power system of claim 2, wherein the operation of controlling the power generation system to adjust the feed water pump comprises at least one of:decreasing an output flowrate of the feed water pump to decrease the power output of the nuclear fission reaction; orincreasing the output flowrate of the feed water pump to increase the power output of the nuclear fission reaction. 5. The nuclear power system of claim 1, further comprising:a containment vessel sized to enclose the reactor vessel such that an open volume is defined between the containment vessel and the reactor vessel; anda boron injection system positioned in the open volume and comprising an amount of boron sufficient to stop the nuclear fission reaction or maintain the nuclear fission reaction at a sub-critical state. 6. The nuclear power system of claim 5 wherein the boron injection system comprises a boron container sized to hold or enclose the amount boron, and wherein the boron container is configured to release the amount of boron directly into the open volume in response to at least one of a predetermined temperature and pressure within the open volume such that the amount of boron is in fluid communication with an inner surface of the containment vessel. 7. A nuclear power system, comprising:a reactor vessel that comprises a reactor core mounted within a volume of the reactor vessel, the reactor core comprising one or more nuclear fuel assemblies configured to generate a nuclear fission reaction;a riser positioned above the reactor core;a primary coolant flow path that extends from a bottom portion of the volume below the reactor core, through the reactor core, within the riser, and through an annulus between the riser and the reactor vessel back to the bottom portion of the volume;a primary coolant that circulates through the primary coolant flow path to receive heat from the nuclear fission reaction and release the received heat to generate electric power in a power generation system fluidly or thermally coupled to the primary coolant flow path;a chemical injection system in fluid communication with the primary coolant flow path; anda control system communicably coupled to the chemical injection system, wherein the control system is configured to perform operations to control one or more parameters of the chemical injection system to control a power output of the nuclear fission reaction independent of any control rod assemblies during the normal operation, the operations comprising:determining that the power output of the nuclear fission reaction is greater than an upper value or less than a lower value;based on the determination, adjusting an amount of a chemical injected into the reactor core from the chemical injection system to adjust the power output of the nuclear fission reaction, wherein the operation of adjusting the amount of the chemical injected into the reactor core from the chemical injection system comprises at least one of:increasing the amount of the chemical injected into the reactor core from the chemical injection system to decrease the power output of the nuclear fission reaction; ordecreasing the amount of the chemical injected into the reactor core from the chemical injection system to increase the power output of the nuclear fission reaction; andsubsequent to the adjustment, determining that the power output is within a range between the upper and lower values. 8. A method for controlling a nuclear fission reaction, comprising:operating a nuclear power system to initiate a nuclear fission reaction, the nuclear power system comprising:a reactor vessel that comprises a reactor core mounted within a volume of the reactor vessel, the reactor core comprising one or more nuclear fuel assemblies configured to initiate and maintain the nuclear fission reaction during a normal operation, wherein the reactor vessel does not include any control rod assemblies therein,a riser positioned above the reactor core,a primary coolant flow path that extends from a bottom portion of the volume below the reactor core, through the reactor core, within the riser, and through an annulus between the riser and the reactor vessel back to the bottom portion of the volume; anda chemical injection system in fluid communication with the primary coolant flow path;circulating a primary coolant through the primary coolant flow path to receive heat from the nuclear fission reaction;transferring the received heat into a power generation system fluidly or thermally coupled to the primary coolant flow path to generate electric power; andcontrolling a power output of the nuclear fission reaction independent of any control rod assemblies during the normal operation by:determining that the power output of the nuclear fission reaction is greater than an upper value or less than a lower value;based on the determination, adjusting an amount of a chemical injected into the reactor core from the chemical injection system to adjust the power output of the nuclear fission reaction; andsubsequent to the adjustment, determining that the power output is within a range between the upper and lower values. 9. The method of claim 8, wherein adjusting the amount of the chemical injected into the reactor core from the chemical injection system comprises at least one of:increasing the amount of the chemical injected into the reactor core from the chemical injection system to decrease the power output of the nuclear fission reaction; ordecreasing the amount of the chemical injected into the reactor core from the chemical injection system to increase the power output of the nuclear fission reaction. 10. The method of claim 8, wherein controlling the power output of the nuclear fission reaction further comprises:based on the determination, controlling the power generation system to adjust at least one of a turbine inlet steam valve or a feed water pump to adjust the power output of the nuclear fission reaction. 11. The method of claim 10, wherein controlling the power generation system to adjust the turbine inlet steam valve comprises at least one of:adjusting the turbine inlet steam valve toward a fully closed position to decrease the power output of the nuclear fission reaction; oradjusting the turbine inlet steam valve toward a fully open position to increase the power output of the nuclear fission reaction. 12. The method of claim 10, wherein controlling the power generation system to adjust the feed water pump comprises at least one of:decreasing an output flowrate of the feed water pump to decrease the power output of the nuclear fission reaction; orincreasing the output flowrate of the feed water pump to increase the power output of the nuclear fission reaction. 13. A pressurized water reactor (PWR), comprising:a control rod assembly-less reactor module that comprises:a reactor vessel comprising a volume sized to enclose a reactor core, a riser, and a steam generator without enclosing a control rod assembly system, wherein the reactor core comprises one or more nuclear fuel assemblies configured to generate a nuclear fission reaction, and wherein the reactor vessel includes a primary coolant flow path that extends from a bottom portion of the volume below the reactor core, through the reactor core, within the riser, and through an annulus between the riser and the reactor vessel back to the bottom portion of the volume;a chemical injection system in fluid communication with the primary coolant flow path; anda containment vessel comprising a volume sized to enclose the reactor vessel and the chemical injection system;a power generation system comprising a steam conduit in fluid communication with the steam generator, a steam turbine-generator, and a steam condenser; anda control system communicably coupled to the power generation system and the chemical injection system, wherein the control system is configured to control a power output of the nuclear fission reaction independent of any control rod assemblies by controlling one or more parameters of at least one of the power generation system or the chemical injection system, and wherein the control system is configured to perform operations to control one or more parameters of the chemical injection system, the operations comprising:determining that the power output of the nuclear fission reaction is greater than an upper value or less than a lower value;based on the determination, adjusting an amount of a chemical injected into the reactor core from the chemical injection system to adjust the power output of the nuclear fission reaction; andsubsequent to the adjustment, determining that the power output is within a range between the upper and lower values. 14. The PWR of claim 13, wherein the volume of the reactor vessel is less than a volume of a conventional reactor vessel sized to enclose a control rod assembly system. 15. The PWR of claim 13, wherein the control system is further configured to adjust the power output of the nuclear fission reaction by controlling at least one of a flowrate or pressure of a steam supply to the steam turbine generator or a flowrate or temperature of a feed water circulated from the steam condenser to the steam generator. 16. The PWR of claim 15, further comprising a passive boron injection system electrically decoupled from a Class 1E power source that is electrically coupled to the reactor module. 17. The PWR of claim 16, wherein the passive boron injection system is positioned in the volume of the containment vessel and fluidly isolated from the volume of the reactor vessel during normal operation of the reactor module. 18. The PWR of claim 17, wherein the passive boron injection system is configured to release an amount of solid boron sufficient to shut down a nuclear fission reaction of the reactor module during an emergency core cooling system (ECCS) event. |
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051827638 | summary | FIELD OF THE INVENTION AND RELATED ART This invention relates generally to a reflection device with a mirror having a multilayered film. In another aspect, the invention relates to a scanning system or an exposure apparatus with such a reflection device. More particularly, the invention is concerned with a reflection device with a mirror having a multilayered film, effective to reflect light of a wavelength 200 nm or less, such as X-rays, vacuum ultraviolet rays or the like, to produce expanded or diffused reflection light. In another aspect, the invention is concerned with a scanning system or an exposure apparatus with such a reflection device. Conventionally, for reflection of light of a wavelength 200 nm or less, having a small divergent angle, such as X-rays or vacuum ultraviolet rays, for example, and for enlarging the diameter of the light, a fixed convex mirror or a swingingly moved convex or flat mirror is used. If, when such a mirror is used, it is desired to provide an increased reflectivity with respect to a particular wavelength, as compared with the other wavelengths, it may be considered that a multilayered film designed with respect to the particular wavelength may be formed on the mirror surface. However, the provision of such a multilayered film on the mirror surface involves such problems as follows. In a fixed convex mirror, different portions of light inputted to the reflection surface of the mirror impinge on different positions on the convex reflection surface of the mirror. As a result, at these positions, the inputted light rays have different angles (angles of incidence) with respect to the reflection surface. On the other hand, generally a multilayered film is so optimized that it exhibits its performance when light of a predetermined wavelength is inputted thereto with a predetermined angle (angle of incidence). Accordingly, in the case of the fixed convex mirror, there is a possibility that, with regard to the predetermined wavelength, only the reflection light rays produced around the peak of the mirror, for example, have intensified strength (as compared with the other wavelengths), and those reflection light rays produced by the other portions of the mirror have intensified strength with respect to some wavelength other than the predetermined wavelength. If this occurs, then the reflection light produced by this mirror has spatial non-uniformness in wavelength, in its section. In a swingable mirror, on the other hand, the inclination of the reflection surface to the light inputted thereto changes with time. As a result, the angle of incidence of the light with respect to the reflection surface also changes with time. This leads to a situation that, in the produced reflection light with which a surface to be illuminated is scanned, such a light component as having a relatively strong light intensity has a varying wavelength. When such a fixed mirror or a swingable mirror is used in an illumination system of an X-ray exposure apparatus, for example, to expose a semiconductor wafer with X-rays reflected by this mirror, since generally the sensitivity of a resist applied to the wafer has a dependence upon the wavelength, the non-uniformness in wavelength or the variation in wavelength such as described above presents uniform exposure. SUMMARY OF THE INVENTION It is accordingly a primary object of the present invention to provide an improved reflection mirror which is free from the above-described inconveniences. It is another object of the present invention to provide a reflection device with such a reflection mirror. It is a further object of the present invention to provide a scanning system with such a reflection device. It is yet another object of the present invention to provide an exposure apparatus with such a reflection device. In accordance with an aspect of the present invention, there is provided a fixed or swingable reflection mirror for reflecting a received radiation beam to produce a reflection beam, wherein the radiation beam is inputted to said reflection mirror with an angle of incidence which changes with position on said reflection mirror, characterized in that: said reflection mirror has a multilayered film effective to provide an increased relative reflectivity with respect to a predetermined wavelength of the reflection beam, wherein a layer of said multilayered film has a thickness which changes with position so as to substantially avoid a shift of said wavelength of the reflection beam dependent upon the angle of incidence. In accordance with another aspect of the present invention, there is provided a reflection device including a movable mirror for reflecting a received radiation beam to produce a reflection beam, wherein said movable mirror is so moved that, with respect to a plane of incidence of the radiation beam, a position and an angle of incidence of the radiation beam are shifted with the movement of said movable mirror, characterized in that: said movable mirror has a multilayered film effective to provide an increased relative reflectivity of a predetermined wavelength of the reflection beam, wherein each layer of said multilayered film has a thickness which changes with position so as to substantially avoid a shift of said wavelength with the shift in the angle of incidence of the radiation beam. In accordance with a further aspect of the present invention, there is provided a scanning system, comprising: a radiation source; a reflection mirror for reflecting a radiation beam from said radiation source to produce a reflection beam, said reflection mirror having a multilayered film effective to provide an increased relative reflectivity with respect to a predetermined wavelength of the reflection beam, wherein a layer of said multilayered film has a thickness which gradually increases with an increase in a distance from said radiation source in a plane of incidence of the radiation beam; and a driving device for swinging said reflection mirror so as to shift a position and an angle of incidence of the radiation beam upon said reflection mirror, in the plane of incidence of the radiation beam, to thereby scanningly deflect the reflection beam. In accordance with yet another aspect of the present invention, there is provided an exposure apparatus having a reflection mirror for reflecting a received radiation beam to produce a reflection beam, to expose a substrate with the reflection beam, wherein the radiation beam is inputted to said reflection mirror with an angle of incidence which changes with position on said reflection mirror, characterized in that: said reflection mirror has a multilayered film effective to provide an increased relative reflectivity with respect to a predetermined wavelength of the reflection beam, wherein each layer of said multilayered film has a thickness which changes with position so as to substantially avoid a shift of said wavelength of the reflection beam dependent upon the angle of incidence. In this type of exposure apparatus, said reflection mirror may be fixed or swingingly moved. In accordance with a still further aspect of the present invention, there is provided an X-ray exposure apparatus, comprising: an X-ray source; and an illumination system for illuminating a mask pattern with X-rays from said X-ray source to expose a wafer to the mask pattern; wherein said illumination system includes a reflection mirror for reflecting the X-rays from said X-ray source to produce a reflection beam and a driving device for swinging said reflection mirror; wherein said reflection mirror has a multilayered film effective to provide an increased relative reflectivity with respect to a predetermined wavelength of the reflection beam; wherein each layer of said multilayered film of said reflection mirror has a thickness which gradually increases with an increase in a distance from said X-ray source in a plane of incidence of the X-rays; and wherein said driving device swings said reflection mirror so as to shift a position and an angle of incidence of the X-rays upon said reflection mirror in the plane of incidence, to thereby scanningly deflect the reflection beam to scan the mask pattern with the deflected reflection beam. In the present invention, as the reflection mirror, one having a flat reflection surface, one having a concave reflection surface or one having a convex reflection surface may by used. In one preferred form of the present invention, the mirror has a flat reflection surface and the driving device rotationally moves the reflection mirror through a rotational shaft space from the reflection surface. In another preferred form, the reflection mirror has a convex reflection surface and the driving device rotationally moves the reflection mirror through a rotational shaft spaced from the reflection surface or, alternatively, the driving device oscillatingly moves the reflection mirror in a direction traversing the radiation beam. Preferably, in the present invention, the reflection mirror is disposed so that the radiation beam such as X-rays is grazingly inputted (at a certain grazing angle) to the reflection surface thereof, so as to ensure enhanced reflectivity. It is to be noted here that the term "plane of incidence" means a plane that contains the radiation beam inputted to the reflection surface of the reflection mirror and the reflection beam produced by this reflection surface. These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings. |
claims | 1. A method of controlling or containing radioactive contamination comprising:providing a neutron absorbing material comprising one or more of the lanthanide elements selected from the group consisting of gadolinium, samarium, europium, erbium and dysprosium in a portable dispenser;spraying said neutron absorbing material to a source of radioactive contamination from said portable dispenser;absorbing emitted neutrons of said radioactive contamination and controlling an expansion of said radioactive contamination;wherein said neutron absorbing material is mixed into cement or provided in an adhesive or provided in a high viscosity matrix. 2. The method of controlling or containing radioactive contamination according to claim 1 wherein said neutron absorbing material comprises a mixture further comprising at least one of hafnium, zirconium, tantalum, silver, indium, hydrogen, and mixtures thereof. 3. The method of controlling or containing radioactive contamination according to claim 1 wherein said neutron absorbing material is provided as one of a powder, a granule, a slurry, and a suspension. |
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description | The present invention relates to platform matching. In particular, the present invention relates to systems and methods to profile applications and benchmark platforms such that the applications may be matched to a most suitable computing platform. Businesses and other entities are becoming increasingly dependent upon custom or semi-custom software applications to perform a variety of processing. For example, financial services businesses develop and utilize a wide range of applications to perform important activities, such as trade processing, decisioning, settlement, and the like. Each application may have different processing characteristics. For example, one application may be particularly dependent on database operations and may require use of a computing platform that has efficient memory and disk storage operation. Another application may be computation intensive, and require a computing platform that is suited for performing efficient floating point operations. As a result, different applications may perform differently on different hardware or computing platforms. Advances in computing hardware and software are continuing at a rapid pace. This rapid advancement has provided a wide range of choices in computing platforms, with different operating systems, processors, storage devices, and memory configurations. A business or other entity may run custom or other software applications on a variety of computing platforms. Unfortunately, however, there is no “one size fits all” computing platform. An application requiring efficient floating point operations may not perform as well on a computing platform that is designed for efficient memory and disk storage applications. It is desirable to provide systems and methods to allow a business or other entity to select the computing platform (from among more than one available platforms) that is the best fit for a particular software application. It is desirable to provide systems and methods to match the processing requirements of applications to the performance results of one or more computing platforms to determine the best platform for an application. It is further desirable to monitor applications during operation and automatically generate application resource usage data for use in further matching each application to a most desirable computing platform. Applicants have recognized a need for an ability to match an application with the best fit computing platform from among more than one available computing platforms. Pursuant to some embodiments, a matching platform is provided to manage and administer this matching. Some embodiments described herein are associated with platform matching systems and methods. As used herein, the phrase “software application” or “application” may refer to a software program (or related set of programs) coded (in any of a number of programming languages or techniques) to perform a desired set of services, tasks or operations on behalf of one or more users. The phrase “computing platform” may refer to computing hardware (including one or more processors, memory storage devices, input and output devices, etc.) and operating system software (such as Linux®, Unix, Windows®, or the like) packaged or integrated together so that software applications may be installed and operated on the computing platform. As used herein, the term “services taxonomy” will refer to the description or characterization of each “service” performed by or utilized by an application. Put another way, as used herein, a “taxonomy” defines terminology associated with an application, and provides a coherent description of the components and conceptual structure of the computing platform requirements of the application. Each application has one or more “services”, and each “service” has a service nature or taxonomy. Each service nature or taxonomy describes or categorizes the primary characteristics of a service. For example, a software application may be described as having one or more concrete service types, such as a database service and a data communication service. Each service may have characteristics other than hardware performance that may be considered. For example, characteristics such as HA capabilities, power consumption, failure rates, licensing costs, support costs, operational costs, and the like may also be considered and included in a given services taxonomy. Further details of how these service descriptions are used pursuant to some embodiments will be described below. Those skilled in the art will appreciate that a number of services taxonomies may be followed or used in conjunction with some embodiments, including the “TOGAF Service Categories” available through the OpenGroup at http://www.opengroup.org. For example, an application taxonomy for a particular application may be shown as follows: Database Management Service: 50% Memory Intensive: 15% Disk Intensive: 35% Network Intensive: 20% Integer Intensive: 30% Network Service: 25% Memory Intensive: 20% Disk Intensive: 30% Network Intensive: 20% Integer Intensive: 30% System and Network Management Service: 25% Memory Intensive: 25% Disk Intensive: 20% Network Intensive: 40% Integer Intensive: 15% That is, the application taxonomy shown above is used to describe an application that is most heavily dependent upon database management services, and is particularly disk intensive in operation. Pursuant to some embodiments, this type of a description of the services profile of an application is used by the matching platform to analyze different computing platforms to identify the most appropriate platform for use with the application. Those skilled in the art will appreciate that other taxonomies and usage profile breakdowns may be used. In general, pursuant to some embodiments, a platform matching process and system are provided in which an application is matched with a best (or most cost effective, or most desirable) computing platform by first generating a baseline performance dataset by testing the application using a known or benchmark computing platform. A resource usage profile is generated using a desired services taxonomy, and suitable benchmark unit tests are selected to evaluate each of the services in the taxonomy. In some embodiments, generating an accurate resource usage profile may require runtime analysis of an application's component services with software tools that can capture resource usage metrics from the baseline platform during testing. In some embodiments, for example if resource usage measurement tools are not available, then a resource usage profile can be generated manually based on expert knowledge of application behavior. Each of the benchmark unit tests are then run on one or more target platforms to arrive at a benchmark result dataset. The matching platform then evaluates the benchmark result dataset by comparing the dataset to the resource usage profile to identify the computing platform that is the “best fit” (or most cost effective, or most desirable) computing platform. The result is a systemized, repeatable and efficient process and system for evaluating a plurality of computing platforms to select a computing platform that will produce the most desirable results when used with a particular software application. In this manner, embodiments allow businesses and other organizations to select the best computing platform (from a set of platforms under evaluation) for use with each software application, resulting in better application performance. Features of some embodiments will now be described by first referring to FIG. 1, where a block diagram of some components of a platform matching system 100 pursuant to some embodiments is shown. As shown, platform matching system 100 includes a matching platform 102 in communication with a plurality of computing platforms 104a-n, one or more client devices 106, application profile and baseline data 108, unit tests 110, and result data 112. In general, matching platform 102 is used to control, administer, and analyze the overall matching process. Matching platform 102 may be configured as a computer server in communication with each of the other devices or systems using a communication network. As used herein, the phrase “communication network” may refer to, by way of example only, a Local Area Network (LAN), a Metropolitan Area Network (MAN), a Wide Area Network (WAN), a proprietary network, a wireless network, an Ethernet network, and/or an Internet Protocol (IP) network such as the Internet, an intranet, a direct (or wired) connection, and/or an extranet. Matching platform 102 might comprise, for example, one or more personal computers, servers or the like. Although a single matching platform 102 is illustrated in FIG. 1, a plurality of platforms might be provided. Matching platform 102 is in communication with one or more client devices 106 which may comprise, for example, networked computers in communication with matching platform 102 and used by, for example, end users who use each client device 106 to interact with matching platform 102. For example, client device 106 may be operated by a technician who wishes to evaluate a number of target platforms 104 for use with a software application. The technician may interact with the matching platform 102 through the client device 106. For example, the technician may use the client device 106 to specify a services taxonomy for the software application, and then use the client device 106 to control or establish a benchmark test sequence performed on a benchmark platform. The technician may then use the client device 106 to select a set of benchmark unit tests to be run on each of the target platforms 104, and then use the device to manage or administer the running of each of the benchmark unit tests on each of the target platforms 104. After all of the benchmark unit tests have been performed, the technician may use the client device 106 to run a “best fit” analysis of each of the target platforms to identify the target platform 104 that is the best or most appropriate platform to use with the software application under evaluation. Further details of this process will be provided below. As shown in FIG. 1, matching platform 102 is in communication with a number of data stores, including, for example, unit test data 110, result data 112, and application profile/baseline data 108. Some or all of these data stores may include data stored in a structured database, such as an XQuery capable database (where the data is stored in one or more XML files), although those skilled in the art will appreciate that other storage techniques and structures may also be used. Details of the data stored in some embodiments will be described further below. To illustrate features of some embodiments, an example will now be provided. This illustrative example will be referenced throughout the remainder of this description. Those skilled in the art will appreciate that this example is illustrative but not limiting—other specific applications, platforms, and tests may be used with, and are within the scope of, embodiments of the present invention. In the illustrative example, a technician is tasked with the responsibility of evaluating two potential target platforms for use as the “production” or live computing platform to run or operate a financial services software application. The technician is responsible for selecting which of the two target platforms is best suited for use with the software application. The two target platforms are: (1) A System ABC computing platform (referred to in the example as the “ABC” platform); and (2) A System DEF computing platform (referred to in the example as the “DEF” platform). In the illustrative example, the software application is referred to as the “ABC application”. The ABC application is a financial services software application that is primarily a database application and that will be used by a number of users on a network. The processing that may occur, pursuant to some embodiments, to match an application (such as the ABC application, in the example) to a most desirable, or most suitable (or “best fit”) computing platform will now be described by first referring to FIG. 2 where a flow diagram of an overview of a platform matching process is provided. The flow charts described herein do not imply a fixed order to the steps, and embodiments of the present invention may be practiced in any order that is practicable. The process of FIG. may be performed, for example, using the matching system 100 of FIG. 1. Processing of FIG. 2 begins at 202 where an application to be matched to a computing platform is analyzed. Pursuant to some embodiments, an application is analyzed to measure its application resource usage profile by measuring, monitoring, and manipulating selected resource metrics. The application resource usage profile data is expressed as a percentage of overall application resource consumption of the application. For example (and as will be described in further detail below), processing at 202 includes determining which resources are used during runtime of an application, and a relative weight of usage of that resource. As a specific illustrative example, memory usage will be expressed as the time that is spent accessing memory during runtime divided by the total application runtime. As another specific illustrative example, integer intensive operations will be expressed as the time that is spent performing integer intensive processing during runtime divided by the total application runtime. The result is an application resource usage profile that identifies the relative weightings of application resource usage for an application (e.g., an application may then be described as being 50% memory intensive, etc.). The resulting application resource usage profile data is stored for each application for later use. Processing continues at 204 where one or more target platforms are analyzed to create data identifying their performance characteristics. Processing at 204 may be performed separately from the processing at 202 so that a separate data store of platform data may be available for matching operations. Platform data may be created by performing a variety of benchmark unit tests on each platform and storing the results in a data store for access by the platform matching system. Processing continues at 206 where a matching process (described further below) is performed to compare the application resource usage profile data with performance data from one or more available target platforms to identify which platform(s) are most suited to the application. In this way, applications may be matched to the best (or most desirable) computing platform, resulting in increased performance, cost savings or efficiency. Pursuant to some embodiments, processing at 206 is performed using matching platform 102 of FIG. 1. At 208, an operator interacting with matching platform 102 may select from the most desirable platforms to pick the target platform to be used with the application. In this manner, an application can be matched to a best or most suitable platform in an efficient and repeatable manner. Further details of the processing to match a target platform to an application will now be described by reference to FIG. 3. FIG. 3 is a flow chart of a platform matching process according to some embodiments of the present invention. According to some embodiments, some or all of the steps of FIG. 3 may be directed or managed by a user interacting with a matching platform (such as platform 102 of FIG. 1) via a client device (such as device 106 of FIG. 1). Instructions and commands may be input by the user into a Graphical User Interface (GUI) display associated with the client device to interact with a matching application operated under the control of the matching platform. Pursuant to some embodiments, the user begins the process of FIG. 3 with several pieces of information—knowledge of the software application, and knowledge of the available computing platforms to be evaluated. For example, the user may be a technician or developer who understands the general design and operation of the software application, as well as the set of computing platforms to be evaluated. Continuing the illustrative example introduced above, the technician may begin the process of FIG. 3 knowing that the ABC application is a financial services software application that is primarily a database application that will be used on a network, and that the ABC and DEF platforms are to be evaluated. Processing begins at 302, where the user generates a baseline set of data to begin the matching process. In some embodiments, the baseline set of data is obtained by running the software application on a known computing platform, and monitoring the resource usage characteristics of the software application. For example, a test hardware configuration may be used that is in communication with the matching platform. The baseline set of data may, for example, include the capture and storage of resource usage characteristics such as: database usage characteristics, data communication characteristics, system and network management characteristics, and the like. These characteristics may be measured using a set of standard benchmark tests designed to test each of the various characteristics. Processing continues at 304 where a user interacts with the matching system to identify resource usage profile data and select a set of appropriate benchmark unit tests to evaluate the identified resources. In some embodiments, an objective is to measure the application resource usage of various system resources and express the application behavior profile as a breakdown by percentage of resources utilized. Applicants have recognized that one challenge is to translate the recorded resource metrics (which are often expressed as a consumption rate such as a disk write expressed as a bits per second throughput metric) into a form that can be expressed as a percentage of overall application resource consumption which is composed of disparate types of resources each with their own unit of measurement. Its not enough to know the throughput of a resources; instead, embodiments correlate the throughput to the amount of time the application spends accessing the resource. For example, an application may be doing 50k bps writes, but if the disk write portion of a 10 minute application runtime is only 10 seconds long, then the disk write operation is only a small percentage of the application resource usage profile. For example, in the illustrative example, the technician may identify that the ABC application has the following baseline resource usage profile, and with the following canonical form weightings: Multithreaded/Multiprocess: 5% Floating Point: 0%; Memory Intensive: 50%; Integer Intensive: 25%; Networking: 20% That is, the technician, based on baseline testing of the application on a known platform, has identified that the ABC application is comprised of services that are heavily dependent upon memory operations (with 50% of the canonical form weightings going toward how a platform performs in memory intensive operations), and is less dependent upon multithreaded and multiprocess services and floating point operation services. This baseline resource usage profile will be used by the matching platform to analyze different computing platforms to identify the most appropriate platform for use with the ABC application. Those skilled in the art will appreciate that other taxonomies and usage profile breakdowns may be used. Pursuant to some embodiments, processing at 304 includes storing the baseline resource usage profile in a datastore accessible by the matching platform (e.g., such as in datastore 108 in FIG. 1). Those skilled in the art will appreciate that this baseline resource usage profile may be expressed in a number of ways. In one example embodiment, the baseline resource usage profile is expressed quantitatively so that it can fit into a ranking system (which will be described further below). In the example, based on the baseline resource usage profile established by the technician, the ABC and DEF computing platforms will be tested and evaluated and then ranked with the memory intensive service test results receiving a weight of 50%, the integer intensive service test results receiving a weight of 25%, etc. Processing at 304 further includes the selection of individual benchmark unit tests to test each of the services identified as of importance to analysis of the application. Those skilled in the art will appreciate that a number of benchmark unit test procedures are available to test different resource usage characteristics. In some embodiments, the matching system may access or use data from a datastore (such as datastore 110 of FIG. 1) to access information about available unit tests. For example, datastore 110 may store a library of available benchmark unit tests. In one example embodiment, data may be stored in a structured manner, by using, for example, a relational database or as XML files in an XQuery capable database. In this manner, data from individual unit tests and matching processes may easily be stored, accessed, and manipulated by the matching platform. Continuing the illustrative example introduced above, in the example, processing at 304 may include the technician selecting baseline unit tests that are appropriate for testing a platform's multithreaded/multiprocess, floating point, memory intensive, integer intensive, and networking services. The technician may select one or more unit test procedures to test each characteristic. As a specific illustrative example, the technician has selected the following unit test procedures to perform on each target computing platform: Unit Test NameCanonical FormACE_QBWMultithreaded/MultiprocessACE_TCPNetworkingMPBMultithreaded/MultiprocessPBMultithreaded/MultiprocessSTREAMSMemory IntensiveThose skilled in the art will appreciate that a wide range of different unit test procedures are available, and that selection of a desired unit test procedure to test a particular service is within the skill of the person of ordinary skill in the art. The above unit test procedures are identified for illustrative purposes only. Once the technician has selected a set of unit test procedures to test each of the target platforms, processing continues at 306, where each of the selected unit test procedures are run on each of the target platforms. Processing continues at 308 where the result data for each of the unit test procedures for each of the target platforms is captured and stored. For example, the unit test data may be stored in datastore 110 of FIG. 1 so that it is readily accessible by matching platform 102 for analysis. In some embodiments, each test may be run multiple times (e.g., there may be multiple sub-tests within each unit test). For example, a unit test may be run with different parameters to identify different performance characteristics of the platform under test. As used herein, the results from each of these sub-tests is referred to as a separate “Y-value” in the unit test results. The test result data from each unit test is stored in a structured manner so that each Y-value result may be identified and compared by the matching platform. Again, in some embodiments, the data is stored in XML format. Processing at 306 and 308 is repeated until all of the selected unit tests have been performed on each of the target platforms and all of the result data has been stored in a data store for analysis by the matching platform. For example, continuing the illustrative example introduced above, processing at 306 and 308 includes performing the ACE_QBW, ACE_TCP, MPB, PB and STREAMS unit test procedures on each of the ABC and DEF platforms. Each of the unit tests are repeated for each Y-value, until a complete dataset representing the full test results for each platform is obtained. In the illustrative example, the unit test results are stored as XML files in an XQuery capable database. The XML may be stored or accessed using the following general format:<benchmark test name>|<system configuration tested>|<y-value>As a result, at the completion of the processing at 306 and 308, in the illustrative example, a data array or table is constructed which has data identifying each unit test for each tested platform, and at each Y-value (or sub test). Those skilled in the art will recognize that other data storage and formatting techniques may be used so long as the data for each test and each platform are readily accessible. Processing continues at 310 where the matching platform (such as matching platform 102 of FIG. 1) accesses the result data and analyzes the data to identify the platform that is the best fit or match for the software application. Further details of the processing at 310 will now be described in conjunction with FIG. 4. FIG. 4 depicts a process 400 for analyzing data to identify the most appropriate platform (or the “best fit”) for a particular software application. Process 400 may be performed by a matching platform such as platform 102 of FIG. 1. For example, process 400 may be initiated by a user interacting with a client device in communication with the matching platform. The matching platform may perform process 400 by executing computer program code configured to perform the process steps of process 400. As a specific illustrative example, the matching platform stores PHP code which, when executed, performs one or more of the steps of process 400. Process 400 begins at 402 where the matching platform accesses the test result data, for each platform, each unit test, and each subtest. As discussed above, in some embodiments, the data is stored as an XML file in an XSD database. In such an embodiment, the processing at 402 includes retrieving the data by an XQuery. Processing at 402 may include creating an object having an array of the result data. For example, the array for the testing done in the illustrative example introduced above may include an array[0]-array[x] having array data including the unit test name (such as “ACE_QBW”), the system configuration tested (such as “ABC”), and a number of Y-values, representing the unit test results for each Y-value or subtest. In some embodiments, processing continues at 404 where the object (including the XQuery results) is then re-ordered into a tree structure that associates the Y-values to the system configurations tested, grouped within the particular unit benchmark test. This allows the matching system to then numerically sort within the Y-value data to determine a score for each platform within each subtest. In some embodiments, the resulting score within each subtest will be in ascending order, while in other embodiments the score will be in descending order (depending upon the particular benchmark, and whether the benchmark results are to be ranked in ascending, i.e. throughput, or descending order, i.e. latency). For example, again continuing the illustrative example, the result of processing at 404 may be an array that ranks the ABC and DEF platforms by their performance in each subunit test within each unit test. Example result data is shown below in TABLE 1 to facilitate understanding of some embodiments: TABLE 1Unit Test: STREAMSY-ValueY-Value ResultPlatformY11846.1567ABC2250.0021DEFY21846.1567ABC2181.8187DEFY32000.0037ABC2511.8187DEFY42000.0037ABC2400.0061DEFAs shown, in the STREAMS unit tests, the DEF system performed better than the ABC system in the subunit tests labeled Y1-Y4 (as STREAMS is a throughput test, higher values are better). Those skilled in the art will appreciate that for some benchmark unit tests, a large number of Y-values or subtests may be performed. Processing pursuant to some embodiments involves sorting each of the Y-value results for each unit test so that a ranking may be determined by the matching platform. Similar sorts are performed for each of the unit tests so that a resulting data structure is created that has unit test data with all Y-values and Y-value results for each of the platforms sorted within each Y-value. Processing continues at 406 where the matching platform operates on the data structures created at 404 to generate platform placement scores within each benchmark unit test. In some embodiments these scores are calculated by having the post-sorted array index values (created in 404) represent the finishing order of a system within a test. For example, in the STREAMS array illustrated above, the ABC system had the top ranking Y-value results for subtests Y1-Y4, and would have an overall platform placement score of “4” (assuming, for simplicity, that there were no other Y-values). Similarly, the DEF system would have an overall platform placement score of “8” because it finished in second index position in each of the four unit subtests. In some embodiments, Y-values for an identical test between two or more platforms may be considered of equal performance if they do not differ by more than a pre-specified margin of error. This optional margin of error value can be specified by the user at a global level (wherein it would apply to all test comparisons), or on a per test basis. Processing continues at 408 where, in some embodiments, the data structure from 406 is transformed into a results data structure representing the scores for each benchmark unit test, by platform. For example, the results data structure for the illustrative example may generally appear as shown below in TABLE 2: TABLE 2“ABC Application” Results DataBenchmark UnitTestPlatformScoreACE_QBWABC50DEF40ACE_TCPABC2DEF4MPBABC9DEF9PBABC6DEF6STREAMSABC4DEF8The results data structure is generated, for example, by taking the post-sorted subunit test results generated in 406, and creating a data structure containing all of the results. Processing continues at 410 where the platform placement scores are normalized within each benchmark unit test. For example, this may be performed to assign a familiar (or human-readable) placement score, such as “1” for “first place”, “2” for “second place”, etc. A “tie” may be signified by two equal normalized results. These normalized scores may also be stored in a data structure for later analysis and viewing. An illustrative data structure is shown below in TABLE 3: TABLE 3“ABC Application” Results DataBenchmark UnitNormalizedTestPlatformResultsACE_QBWABC1DEF2ACE_TCPABC1DEF2MPBABC1DEF1PBABC1DEF1STREAMSABC1DEF2 Processing continues at 412 where the matching platform operates on the data generated above to arrive at a “best fit” or best match platform ranking. For example, the matching platform may multiply the value that represents the percentage of relevance (the weighting) of each service in the taxonomy, to the normalized placement scores (generated at 410). These may be stored in a further data structure. For example, continuing the illustrative example, at the beginning of the matching process the technician determined that the application profile of the ABC application and their relative weightings was as follows: Multithreaded/Multiprocess: 5% Floating Point: 0% Memory Intensive: 50% Integer Intensive: 25% Networking: 20%Since there were three Multithreaded/Multiprocess unit tests selected and performed on each of the platforms, the technician may choose to distribute the 5% weighting of the Multithreaded/Multiprocess service evenly among the three unit tests (although different distributions may be selected). As such, the weightings for each of the unit tests performed in the illustrative example may be: ACE_QBW: 1.66% MPB: 1.66% PB: 1.66% STREAMS: 50% ACE_TCP: 25%In this illustrative example, no Integer Intensive unit tests were performed, so the total weightings allocation for the unit tests does not total 100%. In some embodiments, processing at 412 includes applying the weighting allocations (shown above for the illustrative example) to the normalized rankings (shown in TABLE 3 for the illustrative example) generated at 410. Pursuant to some embodiments, the resulting rankings may again be normalized to familiar placement rankings (e.g., with “1” for first place, etc.). In the illustrative example, the DEF system is the “best fit” platform for the ABC application, with an overall placement score of “74”. The ABC system is the second place platform, with an overall placement score of “143”. Pursuant to some embodiments, different systems can be readily compared even a variety of different benchmark tests are performed which have different meanings (e.g., a value of a Floating Point test is expressed in MFlops, and a value of a Network test may be expressed in terms of throughput or latency). The result is a system that allows different computing platforms to be compared in a meaningful way to identify the platform (or platforms) that are best suited for use in conjunction with a particular software application. Further, pursuant to some embodiments, the comparison of the platforms can be performed using an automated, or partially automated, matching platform, allowing rapid and accurate comparisons. The following illustrates various additional embodiments of the present invention. These do not constitute a definition of all possible embodiments, and those skilled in the art will understand that the present invention is applicable to many other embodiments. Further, although the following embodiments are briefly described for clarity, those skilled in the art will understand how to make any changes, if necessary, to the above-described apparatus and methods to accommodate these and other embodiments and applications. Pursuant to some embodiments, a matching platform (such as the platform 102 of FIG. 1), may automatically analyze a particular software application to generate accurate canonical form weightings for the application. In some embodiments, the canonical form weightings may be generated manually by a technician operating or interacting with the matching platform. In some embodiments, a matching platform (such as the platform 102) is configured to monitor (or receive monitoring data) a variety of applications in their production environments during their normal operation to continually receive and update application resource usage data. In some embodiments, this data may be used to reallocate computing resources, make new platform purchase or allocation decisions, monitor service level agreements, monitor budget and capacity, or the like. For example, referring to FIG. 5, a system 500 is shown which receives application resource usage data from applications in a production environment. As shown, matching platform 502 is in communication with an application 506 deployed in a production environment. While only a single production application is shown, a number of applications may be monitored. Application resource usage data is captured by a data collection tool 508 which monitors selected application resource usage data of the application and transmits the data back to platform matching system 502. Matching platform 502 may use this data to make updated “best fit” recommendations (e.g., by matching the updated application resource usage data to a set of available platforms 504). In some embodiments, matching platform 502 may also use the updated application resource data to monitor service level agreement commitments, changes in application resource usage, and other performance data. The data can be used to reallocate resources, deploy new applications and platforms, or the like. Users and administrators may interact with matching platform 102 of FIG. 1 via one or more client device(s) 106 using a graphical user interface such as the graphical user interface 600 of FIG. 6. Pursuant to some embodiments, users may interact with matching platform 102 by pointing a Web browser associated with a client device 106 to an Internet address (such as a secure site) associated with the matching platform 102. While a wide variety of user interface designs may be used, one suitable design is depicted in FIG. 6. As shown, a user screen is presented which includes a top portion in which a user can select an application for analysis. When an application is selected, details of the application resource usage profile associated with that application are shown. A user may also be provided with sufficient permissions to edit the profile of a selected application. A second portion of the illustrative user interface includes a region for selecting one or more target platforms to analyze the suitability of a match between the selected application and the selected target platforms. Details of each of the selected target platforms may be shown, and a user with sufficient permissions may be able to upload an XML file (or other suitable file format) having details of a new or updated target platform. A third portion of the illustrative user interface includes a region for viewing data showing how well each of the selected target platforms fit the selected application. A number of options may be selected or deselected by a user to view various charts or descriptions relating to the match of the selected platforms to the application. In this way, a user operating a client device may efficiently and easily interact with matching platform 102 to view, analyze, update and edit information associated with an application and one or more platforms. The result is an ability to easily select the platform or platforms that are best suited to a given application. The present invention has been described in terms of several embodiments solely for the purpose of illustration. Persons skilled in the art will recognize from this description that the invention is not limited to the embodiments described, but may be practiced with modifications and alterations limited only by the spirit and scope of the appended claims. For example, while some embodiments have been described in which an application's resource utilization profile is created by a technician who has in-depth knowledge of an application's behavior, other embodiments create a resource utilization profile using a model derived from measurements obtained via performance analysis tools. Further, while an application's resource utilization profile has been described in terms of technical characteristics (such as whether/how much an application is disk intensive, memory intensive, network intensive, etc.), those skilled in the art will now appreciate that an application's profile may be described in terms of other characteristics such as system redundancy features, operational costs, etc. Further, while the use of XML schemas to represent both an application's resource utilization profile and a platform's description and test results, those skilled in the art will recognize that other schemas may be used. |
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abstract | The present invention is directed to a method for portioning high radiation intensity waste and an apparatus thereof. A hanging mechanism hangs both a manual lifting mechanism and a lead shield, wherein the manual lifting mechanism is provided with a net basket hanging chain extending downwards, wherein the net basket hanging chain can be manipulated to be lifted or lowered. The net basket hanging chain is secured to a net basket containing the high radiation intensity waste. The lead shield is arranged under the hanging mechanism and in a path, along which the net basket is lifted or lowered, wherein the lead shield is provided with a space having an opening facing down. |
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description | This application is a division of application, Ser. No. 10/656,091, now U.S. Pat. No. 7,117,120, which was filed on Sep. 5, 2003, which aims priority benefit of provisional application Ser. No. 60/429,158, entitled “Sensorless Control System For Progressive Cavity and Electric Submersible Pumps”, which was filed on Nov. 26, 2002, and provisional application, Ser. No. 60/414,197, entitled “Rod Pump Control System Including Parameter Estimator”, which was filed on Sep. 27, 2002, and is related to application, Ser. No. 10/655,778 entitled “Control System For Progressing Cavity Pumps”, which was filed on Sep. 5, 2003, and application, Ser. No. 10/655,777, now U.S. Pat. No. 7,168,924, entitled “Rod Pump Control System Including Parameter Estimator”, which was filed on Sep. 5, 2003, which was filed on Sep. 5, 2003, which five patent applications are hereby incorporated herein by reference. The present invention relates generally to pumping systems, and more particularly, to methods for determining operating parameters and optimizing the performance of centrifugal pumps, which are rotationally driven and characterized by converting mechanical energy into hydraulic energy through centrifugal activity. Centrifugal pumps are used for transporting fluids at a desired flow and pressure from one location to another, or in a recirculating system. Examples of such applications include, but are not limited to: oil, water or gas wells, irrigation systems, heating and cooling systems, multiple pump systems, wastewater treatment, municipal water treatment and distribution systems. In order to protect a pump from damage or to optimize the operation of a pump, it is necessary to know and control various operating parameters of a pump. Among these are pump speed, pump torque, pump efficiency, fluid flow rate, minimum required suction head pressure, suction pressure, and discharge pressure. Sensors are frequently used to directly measure pump operating parameters. In many applications, the placement required for the sensor or sensors is inconvenient or difficult to access and may require that the sensor(s) be exposed to a harmful environment. Also, sensors add to initial system cost and maintenance cost as well as decreasing the overall reliability of the system. Centrifugal pumping systems are inherently nonlinear. This presents several difficulties in utilizing traditional closed-loop control algorithms, which respond only to error between the parameter value desired and the parameter value measured. Also, due to the nature of some sensors, the indication of the measured parameter suffers from a time delay, due to averaging or the like. Consequently, the non-linearity of the system response and the time lag induced by the measured values makes tuning the control loops very difficult without introducing system instability. As such, it would be advantageous to predict key pump parameters and utilize each in a feed forward control path, thereby improving controller response and stability and reducing sensed parameter time delays. As an example, in a methane gas well, it is typically necessary to pump water off to release trapped gas from an underground formation. This process is referred to as dewatering, where water is a byproduct of the gas production. The pump is operated to control the fluid level within the well, thereby maximizing the gas production while minimizing the energy consumption and water byproduct. As another example, in an oil well, it is desirable to reduce the fluid level above the pump to lower the pressure in the casing, thereby increasing the flow of oil into the well and allowing increased production. This level is selected to reduce the level as much as possible while still providing sufficient suction pressure at the pump inlet. The minimum required suction head pressure of a pump is a function of its design and operating point. Typically, centrifugal pumps are used for both oil and gas production. Generally, the fluid level is sensed with a pressure sensor inserted near the intake or suction side of the pump, typically 1000 to 5000 feet or more below the surface. These down-hole sensors are expensive and suffer very high failure rates, necessitating frequent removal of the pump and connected piping to facilitate repairs. As fluid is removed, the level within the well drops until the inflow from the formation surrounding the pump casing equals the amount of fluid being pumped out. The pump flow rate may be reduced to prevent the fluid level from dropping too far. At a given speed and flow, there is a minimum suction pressure which must be met or exceeded to prevent a condition that could be damaging to the pump. Accordingly, it is common practice to monitor the fluid level within the well and control the operation of the pump to prevent damage. This requires the use of downhole sensors. Downhole sensors are characterized by cost, high maintenance and reliability problems. Likewise, the need for surface flow sensors adds cost to the pump system. The elimination of a single sensor improves the installation cost, maintenance cost and reliability of the system. Also, centrifugal pumps are inefficient when operating at slow speeds and/or flows, wasting electrical power. Therefore, there is a need for a method which would provide reduced flow without sacrificing overall efficiency. Accordingly, it is an objective of the invention to provide a method for estimating the flow and pressure of a centrifugal pump without the use of down hole sensors. Another objective of the invention is to provide a method for determining pump suction pressure and/or fluid levels in the pumping system using the flow and pressure of a centrifugal pump combined with other pumping system parameters. Another objective of the invention is to provide a method for using closed loop control of suction pressure or fluid level to protect the pump from damage due to low or lost flow. Another objective of the invention is to provide a method for improving the dynamic performance of closed loop control of the pumping system. Other objectives of the invention are to provide methods for improving the operating flow range of the pump, for using estimated and measured system parameters for diagnostics and preventive maintenance, for increasing pumping system efficiency over a broad range of flow rates, and for automatically controlling the casing fluid level by adjusting the pump speed to maximize gas production from coal bed methane wells. The apparatus of the present invention must also be of construction which is both durable and long lasting, and it should also require little or no maintenance by the user throughout its operating lifetime. In order to enhance the market appeal of the apparatus of the present invention, it should also be of inexpensive construction to thereby afford it the broadest possible market. Finally, it is also an objective that all of the aforesaid advantages and objectives be achieved without incurring any substantial relative disadvantage. The disadvantages and limitations of the background art discussed above are overcome by the present invention. With this invention, there is provided a method of continuously determining operational parameters of a down hole pump used in oil, water or gas production. In one embodiment, wherein the pump is a centrifugal pump, the pump is rotationally driven by an AC electrical drive motor having a rotor coupled to the pump for rotating the pump element. In deep wells, it is common practice to use an AC electrical drive motor designed to operate at voltages that are several times that of conventional industrial motors. This allows the motors to operate at lower currents, thereby reducing losses in the cable leading from the surface to the motor. In those cases, a step up transformer can be used at the surface to boost the typical drive output voltages to those required by the motor. The method comprises the steps of continuously measuring above ground the electrical voltages applied to the cable leading to the drive motor to produce electrical voltage output signals; continuously measuring above ground the electrical currents applied to the drive motor through the cable to produce electrical current output signals; using a mathematical model of the cable and motor to derive values of instantaneous electrical torque from the electrical voltage output signals and the electrical current output signals; using a mathematical model of the cable and motor to derive values of instantaneous motor velocity from the electrical voltage output signals and the electrical current output signals; and using mathematical pump and system models and the instantaneous motor torque and velocity values to calculate instantaneous values of operating parameters of the centrifugal pump system. In systems using a step up transformer, electrical voltages and currents can be measured at the input to the step up transformer and a mathematical model of the step up transformer can be used to calculate the voltages and currents being supplied to the cable leading to the motor. In one embodiment, the method is used for calculating pump flow rate, head pressure, minimum required suction head pressure, suction pressure, and discharge pressure. In another embodiment, used when accurate calculation of pump flow rate is difficult or impossible, the flow rate is measured above ground in addition to determining the motor currents and motor voltages, and the method is used to calculate head pressure, minimum required suction head pressure, suction pressure, and discharge pressure. The invention provides a method of deriving pump flow rate and head pressure from the drive motor and pumping unit parameters without the need for external instrumentation, and in particular, down hole sensors. The self-sensing control arrangement provides nearly instantaneous readings of motor velocity and torque which can be used for both monitoring and real-time, closed-loop control of the centrifugal pump. In addition, system identification routines are used to establish parameters used in calculating performance parameters that are used in real-time closed-loop control of the operation of the centrifugal pump. In one embodiment, wherein the operating parameters are pump head pressure and flow rate, the method includes the steps of using the calculated value of the flow rate at rated speed of the pump under the current operating conditions and the instantaneous value of motor speed to obtain pump efficiency and minimum required suction head pressure. The present invention includes the use of mathematical pump and system models to relate motor torque and speed to pump head pressure, flow rate and system operational parameters. In one embodiment, this is achieved by deriving an estimate of pump head pressure and flow rate from motor currents and voltage measurements which are made above ground. The results are used to control the pump to protect the pump from damage, to estimate system parameters, diagnose pumping system problems and to provide closed-loop control of the pump in order to optimize the operation of the pump. Protecting the pump includes detecting blockage, cavitation, and stuck pump. Comparisons of calculated flow estimates and surface flow measurements can detect excess pump wear, flow blockage, and tubing leaks. The operation of a centrifugal pump is controlled to enable the pump to operate periodically, such that the pump can achieve a broad average flow range while maintaining high efficiency. This obviates the need to replace a centrifugal pump with another pump, such as a rod beam pump, when fluid level or flow in the well decreases over time. In accordance with another aspect of the invention, a check valve is used to prevent back flow during intervals in which the pump is turned off. In accordance with a further aspect of the invention, an optimizing technique is used in the production of methane gas wherein it is necessary to pump water off an underground formation to release the gas. The optimizing technique allows the fluid level in the well to be maintained near an optimum level in the well and to maintain the fluid at the optimum level over time by controlling pump speed to raise or lower the fluid level as needed to maintain the maximum gas production. This is done by measuring and/or calculating fluid flow, gas flow, casing gas pressure, and fluid discharge pressure at the surface. Selected fluid levels are used to define a sweet zone. This can be done manually or using a search algorithm. The search algorithm causes the fluid level to be moved up and down, searching for optimum performance. The search algorithm can be automatically repeated at preset intervals to adjust the fluid level to changing well conditions. Uses of the self-sensing pump control system also include, but are not limited to HVAC systems, multi-pump control, irrigation systems, wastewater systems, and municipal water systems. Variables used throughout the drawings have the following form: A variable with a single subscript indicates that the reference is to an actual element of the system as in Tm for the torque of the motor or a value that is known in the system and is stable as in Xp for the depth of the pump. A variable with a second subscript of ‘m’, as in Vmm for measured motor voltage, indicates that the variable is measured on a real-time basis. Similarly, a second subscript of ‘e’ indicates an estimated or calculated value like Tme for estimated motor torque; a second subscript of ‘c’ indicates a command like Vmc for motor voltage command; and a second subscript of ‘f’ indicates a feedforward command like Umf for motor speed feedforward command. Variables in bold type, as in Vs for stator voltage, are vector values having both magnitude and direction. Referring to FIG. 1, the present invention is described with reference to an oil well 30 wherein oil is to be pumped from an underground formation 22. The well includes an outer casing 39 and an inner tube 38 that extend from ground level to as much as 1000 feet or more below ground level. The casing 39 has perforations 26 to allow the fluid in the underground formation to enter the well bore. It is to be understood that water and gas can be combined with oil and the pump can be used for other liquids. The control apparatus can also be used for pumping water only. The bottom of the tube generally terminates below the underground formations. A centrifugal pump of the type known as an electric submersible pump (ESP) 32 is mounted at the lower end of the tube 38 and includes one or more centrifugal pump members 34 mounted inside a pump housing. The pump members are coupled to and driven by a drive motor 36 which is mounted at the lower end of the pump housing. The tube 38 has a liquid outlet 41 and the casing 39 has a gas outlet 42 at the upper end above ground level 31. An optional check valve 28 may be located on the discharge side of the pump 32 to reduce back flow of fluid when the pump is off. These elements are shown schematically in FIG. 1. The operation of the pump 32 is controlled by a pump control system and method including a parameter estimator in accordance with the present invention. For purposes of illustration, the pump control system 20 is described with reference to an application in a pump system that includes a conventional electric submersible pump. The electric submersible pump includes an electric drive system 37 connected to motor 36 by motor cables 35. A transformer (not shown) is sometimes used at the output of the drive to increase voltage supplied to the motor. The motor rotates the pump elements that are disposed near the bottom 33 of the well. The drive 37 receives commands from controller 50 to control its speed. The controller 50 is located above ground and contains all the sensors and sensor interface circuitry and cabling necessary to monitor the performance of the pump system. The motor 36 can be a three-phase AC induction motor designed to be operated from line voltages in the range of 230 VAC to several thousand VAC and developing 5 to 500 horsepower or higher, depending upon the capacity and depth of the pump. Pump Control System Referring to FIG. 2, there is shown a simplified representation of the pump control system 20 for the pump 32. The pump control system 20 controls the operation of the pump 32. In one embodiment, the casing fluid level is estimated using pump flow rate and head pressure estimates which, in turn, can be derived from values of motor speed and torque estimates. The pump flow rate and head pressure estimates are combined with system model parameters to produce a casing fluid level estimate. In one preferred embodiment, a pump model and system model are used to produce estimated values of pump flow rate and casing fluid level for use by a pump controller in producing drive control signals for the pump 32. Alternatively, the measured discharge flow rate of the pump 32 can be obtained using measurements from the surface flow sensor 59 and combined with the estimates produced by the pump and system models to produce the casing fluid level estimate. This is particularly useful when the configuration of the pump makes it difficult to accurately calculate pump flow rate from the mechanical inputs to the pump. While in a primary function the estimated parameters are used for control, the parameters also can be used for other purposes. For example, the estimated parameters can be compared with those measured by sensors or transducers for providing diagnostics alarms. The estimated parameters may also be displayed to setup, maintenance or operating personnel as an aid to adjusting or troubleshooting the system. In one embodiment, values of flow and pressure parameters are derived using measured or calculated values of instantaneous motor currents and voltages, together with pump and system parameters, without requiring down hole sensors, fluid level meters, flow sensors, etc. The flow and pressure parameters can be used to control the operation of the pump 32 to optimize the operation of the system. In addition, pump performance specifications and system identification routines are used to establish parameters used in calculating performance parameters that are used in real time closed-loop control of the operation of the pump. The pump control system 20 includes transducers, such as above ground current and voltage sensors, to sense dynamic variables associated with motor load and velocity. The pump control system further includes a controller 50, a block diagram of which is shown in FIG. 2. Above ground current sensors 51 of interface devices 140 are coupled to a sufficient number of the motor cables 35, two in the case of a three phase AC motor. Above ground voltage sensors 52 are connected across the cables leading to the motor winding inputs. The current and voltage signals produced by the sensors 51 and 52 are supplied to a processing unit 54 of the controller 50 through suitable input/output devices 53. The controller 50 further includes a storage unit 55 including storage devices which store programs and data files used in calculating operating parameters and producing control signals for controlling the operation of the pump system. This self-sensing control arrangement provides nearly instantaneous estimates of motor velocity and torque, which can be used for both monitoring and real-time, closed-loop control of the pump. For example, in one embodiment, instantaneous estimates of motor velocity and torque used for real- time, closed-loop control are provided at the rate of about 1000 times per second. Motor currents and voltages are sensed or calculated to determine the instantaneous speed and torque produced by the electric motor operating the pump. As the centrifugal pump 32 is rotated, the motor 36 is loaded. By monitoring the motor currents and voltages above ground, the calculated torque and speed produced by the motor 36, which may be below ground, are used to calculate estimates of fluid flow and head pressure produced by the pump 32. More specifically, interface devices 140 include the devices for interfacing the controller 50 with the outside world. None of these devices are located below ground. Sensors in blocks 51 and 52 can include hardware circuits which convert and calibrate the current and voltage signals into current and flux signals. After scaling and translation, the outputs of the voltage and current sensors can be digitized by analog to digital converters in block 53. The processing unit 54 combines the scaled signals with cable and motor equivalent circuit parameters stored in the storage unit 55 to produce a precise calculation of motor torque and motor velocity. Block 59 contains an optional surface flow meter which can be used to measure the pump flow rate. Block 59 may also contain signal conditioning circuits to filter and scale the output of the flow sensor before the signal is digitized by analog to digital converters in block 53. Pump Control Referring to FIG. 3, which is a functional block diagram of the pump control system 20 for a pump 32 where the pump flow rate to pump power relationship allows pump flow rate to be calculated, the pump 32 is driven by a drive 37 and motor 36 to transfer fluid within a system 150. The operation of the motor 36 is controlled by the drive 37 and controller 50 which includes a pump model 60, system model 80, fluid level feedforward controller 90, fluid level feedback controller 100, motor vector controller 130 and interface devices 140. More specifically, block 140, which is located above ground, can include hardware circuits which convert and calibrate the motor current signals Im (consisting of individual phase current measurements Ium and Ivm in the case of a three phase motor) and voltage signals Vm (consisting of individual phase voltage measurements Vum, Vvm, and Vwm in the case of a three phase motor) into motor current and flux signals. After scaling and translation, the outputs of the voltage and current sensors can be digitized by analog to digital converters into measured voltage signals Vmm and measured current signals Imm. The motor vector controller 130 combines the scaled signals with cable and motor equivalent circuit parameters to produce a precise calculation of motor electrical torque Tme and velocity Ume. Automatic identification routines can be used to establish the cable and motor equivalent circuit parameters. The pump model 60 calculates the values of parameters, such as pump flow rate Qpe, pump head pressure Hpe, pump head pressure at rated speed Hre, minimum required suction head pressure Hse, pump efficiency Epe, and pump safe power limit Ple relating to operation of the pump 32 from inputs corresponding to motor torque Tme and motor speed Ume without the need for external flow or pressure sensors. This embodiment is possible for pumps where the relationship of pump flow rate to pump power at rated speed, as shown in FIG. 13, is such that each value of power has only one unique value of pump flow rate associated with it throughout the range of pump flows to be used. Further, the system model 80 derives estimated values of the pump suction pressure Pse, flow head loss Hfe, pump discharge pressure Pde and the casing fluid level Xce from inputs corresponding to discharge flow rate value Qpe and the head pressure value Hpe of the pump. The fluid level feedforward controller 90 uses the pump head pressure at rated speed value Hre, flow head loss value Hfe and commanded fluid level Xcc to calculate a motor speed feedforward command Umf. The fluid level feedback controller 100 compares the commanded fluid level Xcc with static and dynamic conditions of the fluid level value Xce to calculate a motor velocity feedback command Ufc. Motor velocity feedback command Ufc and feedforward command Umf are added in summing block 79 to yield the motor velocity command Umc. Motor vector controller 130 uses the motor speed command Umc to generate motor current commands Imc and voltage commands VNc. Interface devices in block 140, which can be digital to analog converters, convert the current commands Imc and voltage commands Vmc into signals which can be understood by the drive 37. These signals are shown as Ic for motor current commands and Vc for motor winding voltage commands. In installations with long cables and/or step up transformers, the signals Ic and Vc would be adjusted to compensate for the voltage and current changes in these components. Referring to FIG. 4, which is a functional block diagram of the pump control system 20 for a pump 32 where the pump flow rate is measured above ground, the pump 32 is driven by a drive 37 and motor 36 to transfer fluid within a system 150. The operation of the motor 36 is controlled by the drive 37 and controller 50 which includes a pump model 260, system model 80, fluid level feedforward controller 90, fluid level feedback controller 100, motor vector controller 130 and interface devices 140. More specifically, block 140, which is located above ground, can include hardware circuits which convert and calibrate the motor current signals Im (consisting of individual phase current measurements Ium and Ivm in the case of a three phase motor) and voltage signals Vm (consisting of individual phase voltage measurements Vum, Vvm, and Vwm in the case of a three phase motor) into motor current and flux signals. After scaling and translation, the outputs of the voltage and current sensors can be digitized by analog to digital converters into measured voltage signals Vmm and measured current signals Imm. The motor vector controller 130 combines the scaled signals with cable and motor equivalent circuit parameters to produce a precise calculation of motor electrical torque Tme and velocity Ume. Automatic identification routines can be used to establish the cable and motor equivalent circuit parameters. In this embodiment, block 140 also may contain hardware circuits which convert above ground flow rate into an electrical signal that can be digitized by analog to digital converters into the measured flow signal Qpm for use by the pump model 260 and the system model 80. The pump model 260 calculates the values of parameters pump head pressure Hpe, pump head pressure at rated speed Hre, minimum required suction head pressure Hse, pump efficiency Epe, and pump safe power limit Ple relating to operation of the pump 32 from inputs corresponding to flow Qpm as measured by a flow sensor and motor speed Ume without the need for other external sensors. This embodiment is used for pumps where the relationship of pump flow rate to pump power at rated speed is such that there is not a unique pump flow rate for each value of pump power. Further, the system model 80 derives estimated values of the pump suction pressure Pse, flow head loss Hfe, pump discharge pressure Pde and the casing fluid level Xce from inputs corresponding to discharge flow rate value Qpm and the head pressure value Hpe of the pump. The fluid level feedforward controller 90 uses the motor speed value Ume, flow head loss value Hfe and commanded fluid level Xcc to calculate a motor speed feedforward command Umf. The fluid level feedback controller 100 compares the commanded fluid level Xcc with static and dynamic conditions of the fluid level value Xce to calculate a motor velocity feedback command Ufc. Motor velocity feedback command Ufc and feedforward command Umf are added in summing block 79 to yield the motor velocity command Umc. Motor vector controller 130 uses the motor speed command Umc to generate motor current commands Imc and voltage commands Vmc. Interface devices in block 140, which can be digital to analog converters, convert the current commands Imc and voltage commands Vmc into signals which can be understood by the drive 37. These signals are shown as Ic for motor current commands and Vc for motor winding voltage commands. In installations with long cables and/or step up transformers, the signals Ic and Vc would be adjusted to compensate for the voltage and current changes in these components. The controller 50 provides prescribed operating conditions for the pump and/or system. To this end, either pump model 60 or pump model 260 also can calculate the efficiency Epe of the pump for use by the controller 50 in adjusting operating parameters of the pump 32 to determine the fluid level Xc needed to maximize production of gas or produced fluid and/or the fluid level Xc needed to maximize production with a minimum power consumption. The controller 50 (FIG. 3 and FIG. 4) uses the parameter estimates to operate the pump so as to minimize energy consumption, optimize gas flow, and maintain the fluid level to accomplish the objectives. Other inputs supplied to the controller 50 include the commanded casing fluid level Xcc and values representing casing pressure Pc and tubing pressure Pt (FIG. 8). Values representing casing pressure Pc and tubing pressure Pt may each be preset to approximate values as part of the system setup or, as is preferable in situations where these values are likely to vary during operation of the system, the controller 50 can use values measured by sensors mounted above ground and connected to the controller 50 through appropriate signal conditioning and interface circuitry. The controller 50 (FIG. 3 and FIG. 4) optimizes use of electrical power as the flow delivery requirements change and can determine fluid level without using down hole sensors and, in one preferred embodiment, without using surface flow sensors. As will be shown, the control operations provided by the controller 50 include the use of the pump model 60 (FIG. 3) or pump model 260 (FIG. 4) and system model 80 (FIG. 3 or FIG. 4) to relate mechanical pump input to output flow rate and head pressure. In one embodiment (FIG. 3), this is achieved by deriving an estimate of pump flow rate from above ground measurements of motor current and voltage. In another embodiment (FIG. 4), the pump flow rate is measured using a surface flow sensor. From the flow value thus obtained, the pump head pressure, efficiency and other pump operating parameters are determined using pump curve data. The results are used to control the pump 32 to protect it from damage and to provide closed-loop control of the pump 32 in order to optimize the operation of the pumping system. Protecting the pump 32 includes detecting blockage, cavitation, and stuck pump. Moreover, the operation of the pump 32 can be controlled to enable it to operate periodically, such that the pump can operate efficiently at a decreased average pump flow rate. This obviates the need to replace the electric submersible pump with another pump, such as a rod beam pump, when fluid level or inflow within the well decreases over time. Further, in accordance with the invention, the pump can be cycled between its most efficient operating speed and zero speed at a variable duty cycle to regulate average pump flow rate. Referring to FIG. 1, in cases where electric submersible pumps are being operated at a low duty cycle, such as on for twenty-five percent of the time and off for seventy-five percent of the time, a check valve 28 may be used down hole to prevent back flow of previously pumped fluid during the portion of each cycle that the pump is off. The check valve 28 can be designed to allow a small amount of leakage. This allows the fluid to slowly drain out of the tube 38 to allow maintenance operations. Pump Model Reference is now made to FIG. 5, which is a block diagram of an algorithm for the pump model 60 of the pump 32 as used in the embodiment shown in FIG. 3 where it is possible to calculate an estimate of pump flow rate. The pump model 60 is used to calculate estimates of parameters including head pressure Hpe, fluid flow Qpe, minimum required suction head pressure Hse, pump mechanical input power limit Ple, and pump efficiency Epe. In one preferred embodiment, the calculations are carried out by the processing unit 54 (FIG. 2) under the control of software routines stored in the storage devices 55 (FIG. 2). Briefly, values of motor torque Tme and motor speed Ume are used to calculate the mechanical power input to the pump Ppe which is used with the motor speed value Ume to calculate what the flow Qre would be at rated pump speed Ur. This value of Qre is used with formulas derived from published pump data and pump affinity laws to solve for the pump head at rated speed Hre, pump efficiency Epe, and minimum required suction head pressure required Hse. Using the value of motor speed Ume, the values of pump head at rated speed Hre and pump flow rate at rated speed Qre are scaled using pump affinity laws to estimated values of pump head Hpe and pump flow rate Qpe, respectively. With reference to the algorithm illustrated in FIG. 5, the value for pump mechanical input power Ppe is obtained by multiplying the value for motor torque Tme by the value of motor speed Ume in block 61. In block 62, the mechanical input power applied to the pump, Ppe is multiplied by a scaling factor calculated as the cube of the ratio of the rated speed of the pump Ur to the current speed Ume to yield a value representing the power Pre which the pump would require at rated pump speedUr. This scaling factor is derived from affinity laws for centrifugal pumps. Block 63 derives a value of the pump flow rate Qre at the rated speed with the current conditions. This value of pump flow rate Qre at rated speed is calculated as a function of power Pre at rated speedUr. Pump manufacturers often provide pump curves such as the one shown in FIG. 13, which relates pump mechanical input power Pp to flow Qre at rated speed. Alternatively, such a curve can be generated from values of pump head as a function of flow at rated speed, pump efficiency as a function of flow at rated speed, and the fluid density. The function of block 63 (FIG. 5) is derived from the data contained in the graph. One of two methods is used to derive the function of block 63 from the data in this graph. The first method is to select data points and use curve fitting techniques, which are known, to generate an equation describing power as a function of flow. Solving the equation so flow is given as a function of power will provide one method of performing the calculation in block 63. One simple method is to fit the data to a second order equation. In the case of a second order equation, the solution for flow is in the form of a quadratic equation which yields two solutions of flow for each value of power. In this case, block 63 must contain a means of selecting flow value Qre from the two solutions. This is usually easy as one of the values will be much less likely than the other, if not impossible as in a negative flow solution. The second method is to select several points on the graph to produce a look-up table of flow versus power. With such a look-up table, it is relatively easy to use linear interpolation to determine values of Qre between data points. In block 64, the value for flow at rated speed, Qre, is scaled by the ratio of the current speed Ume to the rated speed Ur to yield the pump flow rate value Qpe. This scaling factor is derived from affinity laws for centrifugal pumps. Block 65 calculates a value of head pressure at rated speed Hre as a function of flow at rated speed Qre. Pump manufacturers provide pump curves such as the one shown in FIG. 11, which relates pump head pressure to flow at rated speed. The function of block 65 is uses the data contained in the graph. One of two methods is used to derive the function of block 65 from the data in this graph. The first method is to select data points and use curve fitting techniques, which are known, to generate an equation describing pump head pressure as a function of flow. The second method is to select several points on the graph to produce a look-up table of pump head pressure versus flow. With such a look-up table, it is relatively easy to use linear interpolation to determine values of Hre between data points. In block 66, the value for pump head pressure at rated speed, Hre, is scaled by the square of ratio of the current speed Ume to the rated speed Ur to yield the pump head pressure value Hpe. This scaling factor is derived from affinity laws for centrifugal pumps. The efficiency of the pump is calculated in block 67 to yield the value Epe. Pump efficiency is the ratio of fluid power output divided by mechanical power input. Pump manufacturers provide pump curves such as the one shown in FIG. 12, which relates pump efficiency to pump flow rate at rated speed. The function of block 67 is derived from the data contained in the graph. One of two methods is used to derive the function of block 67 from the data in this graph. The first method is to select data points and use curve fitting techniques, which are known, to generate an equation describing pump efficiency as a function of flow. The second method is to select several points on the graph to produce a look-up table of pump efficiency versus flow. With such a look-up table, it is relatively easy to use linear interpolation to determine values of Epe between data points. An estimate of the suction head pressure required at the input of the pump, Hse, is calculated in block 68. Pump manufacturers provide pump curves such as the one shown in FIG. 11, which relates the pump's minimum required suction head pressure Hs to pump flow rate at rated speed. The function of block 68 is derived from the data contained in the graph. One of two methods is used to derive the function of block 68 from the data in this graph. The first method is to select data points and use curve fitting techniques, which are known, to generate an equation describing pump suction pressure required as a function of flow. The second method is to select several points on the graph to produce a look-up table of pump suction pressure required versus pump flow rate. With such a look-up table, it is relatively easy to use linear interpolation to determine values of Sre between data points. A mechanical input power limit for the pump is calculated in block 69. The end of curve power level Pe as shown in FIG. 13 is scaled by the cube of the ratio of the current speed Ume to the rated speed Ur to provide the mechanical input power limit estimate Ple. This scaling factor is derived from affinity laws for centrifugal pumps. The mechanical input power limit value can be used to limit the torque and/or the speed of the pump, and thereby limit power, to levels which will not damage the pump. Reference is now made to FIG. 6, which is a block diagram of an algorithm for the pump model 260 of the pump 32 as used in the embodiment shown in FIG. 4 where it is not possible to calculate an estimate of pump flow rate. The pump model 260 is used to calculate estimates of parameters including head pressure Hpe, minimum required suction head pressure Hse, pump mechanical input power limit Ple, and pump efficiency Epe. In one preferred embodiment, the calculations are carried out by the processing unit 54 (FIG. 2) under the control of software routines stored in the storage devices 55 (FIG. 2). Briefly, values of measured fluid flow Qpm and motor speed Ume are used to calculate what the flow Qre would be at rated pump speed Ur. This value of flow Qre is used with formulas derived from published pump data and pump affinity laws to solve for the pump head at rated speed Hre, pump efficiency Epe, and minimum required suction head pressure required Hse. Using the value of motor speed Ume, the values of pump head at rated speed Hre and pump flow rate at rated speed Qre are scaled using pump affinity laws to estimated values of pump head Hpe and pump flow rate Qpe respectively. With reference to the algorithm illustrated in FIG. 6, in block 264, the value for measured pump flow rate Qpm is scaled by the ratio of the rated speed of the pump Ur to the speed of the pump Ume to derive an estimate of the flow of the pump at rated speed Qre. This scaling factor is derived from affinity laws for centrifugal pumps. Block 265 calculates a value of head pressure at rated speed Hre as a function of flow Qre at rated speed Ur. Pump manufacturers provide pump curves such as the one shown in FIG. 11, which relates pump head pressure to flow at rated speed. The function of block 265 is derived from the data contained in the graph. One of two methods is used to derive the function of block 265 from the data in this graph. The first method is to select data points and use curve fitting techniques, which are known, to generate an equation describing pump head pressure as a function of flow. The second method is to select several points on the graph to produce a look-up table of pump head pressure versus flow. With such a look-up table, it is relatively easy to use linear interpolation to determine values of Hre between data points. In block 266, the value for pump head pressure at rated speed, Hre, is scaled by the square of the ratio of the current speed Ume to the rated speed Ur to yield the pump head pressure value Hpe. This scaling factor is derived from affinity laws for centrifugal pumps. The efficiency of the pump is calculated in block 267 to yield the value Epe. Pump efficiency is the ratio of fluid power output divided by mechanical power input. Pump manufacturers provide pump curves such as the one shown in FIG. 12, which relates pump efficiency to pump flow rate at rated speed. The function of block 267 is derived from the data contained in the graph. One of two methods is used to derive the function of block 267 from the data in this graph. The first method is to select data points and use curve fitting techniques, which are known, to generate an equation describing pump efficiency as a function of flow. The second method is to select several points on the graph to produce a look-up table of pump efficiency versus flow. With such a look-up table, it is relatively easy to use linear interpolation to determine values of Epe between data points. An estimate of the suction head pressure required at the input of the pump, Hse, is calculated in block 268. Pump manufacturers provide pump curves such as the one shown in FIG. 11, which. relates the pump's minimum required suction head pressure Hs to pump flow rate at rated speed. The function of block 268 is derived from the data contained in the graph. One of two methods is used to derive the function of block 68 from the data in this graph. The first method is to select data points and use curve fitting techniques, which are known, to generate an equation describing pump suction pressure required as a function of flow. The second method is to select several points on the graph to produce a look-up table of pump suction pressure required versus pump flow rate. With such a look-up table, it is relatively easy to use linear interpolation to determine values of Sre between data points. A mechanical input power limit for the pump is calculated in block 269. The end of curve power level Pe as shown in FIG. 13 is scaled by the cube of the ratio of the current speed Ume to the rated speed Ur to provide the mechanical input power limit estimate Ple. This scaling factor is derived from affinity laws for centrifugal pumps. The mechanical input power limit value Ple can be used to limit the torque and/or the speed of the pump, and thereby limit power, to levels which will not damage the pump. System Model Reference is now made to FIG. 7, which is a block diagram of an algorithm for the system model 80 of the fluid system 150. The system model 80 is used to calculate estimates of system parameters including pump suction pressure Pse, pump discharge pressure Pde, head flow loss Hfe and casing fluid level Xce. In one preferred embodiment, the calculations are carried out by the processing unit 54 (FIG. 2) under the control of software routines stored in the storage devices 55. FIG. 14 diagrammatically presents the actual reservoir system parameters used in FIG. 5 for the pump 32. Ps is the pump suction pressure, Pd is the pump discharge pressure, Hp is the pump head pressure, Hf is the flow head loss and Qp is the pump flow rate. Lp is the length of the pump, Lt (not shown) is the length of the tubing from the pump outlet to the tubing outlet, Xp is the pump depth and Xc is the fluid level within the casing 39 (FIG. 1). Pc is the pressure within the casing and Pt is the pressure within the tubing 38. Parameter Dt is the tubing fluid specific weight, parameter Dc is the casing fluid specific weight, and parameter Dp (not shown) is the specific weight of the fluid within the pump. Briefly, with reference to FIG. 7, a value representing pump flow rate Qp (such as measured surface flow rate Qpm or estimated pump flow rate Qpe), pump head pressure estimate Hpe, and values of tubing pressure Pt and casing pressure Pc are combined with reservoir parameters of pump depth Xp and pump length Lp to determine pump suction pressure Pse and casing fluid level Xce. More specifically, the processing unit 54 responds to the value representing pump flow rate Qp. This value representing pump flow rate Qp can be either the value of Qpe produced by the pump model 60, as shown in FIG. 3, or the value of Qpm as shown in FIG. 4 from a surface flow sensor 59 (FIG. 2). This pump flow rate value is used to calculate a tubing flow head loss estimate Hfe in block 81. The head loss equation for Hfe presented in block 81 can be derived empirically and fit to an appropriate equation or obtained from well known relationships for incompressible flow. One such relationship for flow head loss estimate Hfe is obtained from the Darcy-Weisbach equation:Hfe=f[(L/d)(V2/2G)] (1)where f is the friction factor, L is the length of the tubing, d is the inner diameter of the tubing, V is the average fluid velocity (Q/A, where Q is the fluid flow and A is the area of the tubing), and G is the gravitational constant. For laminar flow conditions (Re<2300), the friction factor f is equal to 64/Re, where Re is the Reynolds number. For turbulent flow conditions, the friction factor can be obtained using the Moody equation and a modified Colebrook equation, which will be known to one of ordinary skill in the art. For non-circular pipes, the hydraulic radius (diameter) equivalent may be used in place of the diameter in equation (1). Furthermore, in situ calibration may be employed to extract values for the friction factor f in equation (1) by system identification algorithms. Commercial programs that account for detailed hydraulic losses within the tubing are also available for calculation of fluid flow loss factors. It should be noted that although fluid velocity V may change throughout the tubing length, the value for fluid velocity can be assumed to be constant over a given range. The suction pressure Pse is calculated by adding the head loss Hfe calculated in block 81 with the pump depth Xp and subtracting the pump head pressure Hpe in summing block 82. The output of summing block 82 is scaled by the tubing fluid specific weight Dt in block 83 and added to the value representing tubing pressure Pt in summing block 84 to yield the suction pressure Pse. The pump discharge pressure Pde is calculated by scaling the length of the pump Lp by the casing fluid specific weight Dc in block 87. The pump head pressure Hpe is then scaled by the pump fluid specific weight Dp in block 88 to yield the differential pressure across the pump, Ppe. Pump pressure Ppe is then added to the pump suction pressure Pse and the negative of the output of scaling block 87 in summing block 89 to calculate the pump discharge pressure Pde. The casing fluid level Xce is calculated by subtracting casing pressure Pc from the suction pressure Pse, calculated in summing block 84, in summing block 85. The result of summing block 85 is scaled by the reciprocal of the casing fluid specific weight Dc in block 86 to yield the casing fluid level Xce. The casing fluid specific weight Dc, pump fluid specific weight Dp, and tubing fluid specific weight Dt may differ due to different amounts and properties of dissolved gases in the fluid. At reduced pressures, dissolved gases may bubble out of the fluid and affect the fluid density. Numerous methods are available for calculation of average fluid density as a function of fluid and gas properties which are known in the art. Fluid Level Feedforward Controller Referring to FIG. 8, there is shown a process diagram of the fluid level feedforward controller 90. The fluid level feedforward controller 90 uses flow head loss Hfe, pump head pressure Hre at rated speed and other parameters to produce a motor speed feedforward command Umf to be summed with the motor speed feedback command Ufc in summing block 79 (FIG. 3 and FIG. 4) to produce the motor speed command Umc for the motor vector controller 130. This speed signal is based on predicting the pump speed required to maintain desired pressures, flows and levels in the pumping system. Use of this controller reduces the amount of fluid level error in the fluid level feedback controller 100 (FIG. 9), allowing conservative controller tuning and faster closed loop system response. More specifically, in scaling block 91, the value of casing pressure Pc is scaled by the inverse of the casing fluid specific weight Dc to express the result in equivalent column height (head) of casing fluid. Similarly, in scaling block 92, the value of tubing pressure Pt is scaled by the inverse of the tubing fluid specific weight Dt to express the result in equivalent column height (head) of tubing fluid. In summing block 93, the negative of the output of block 91 is added to the output of block 92, the pipe head flow loss Hfe, the depth of the pump Xp, and the negative of the commanded casing fluid level Xcc to obtain pump head pressure command Hpc. The flow head loss Hfe is the reduction in pressure due to fluid friction as calculated in block 81 (FIG. 7). The commanded pump head Hpc is the pressure that the pump must produce as a result of the inputs to summing block 93. The values of casing pressure Pc and tubing pressure Pt can be measured in real time using above ground sensors in systems where they are variable or fixed for systems where they are relatively constant. The values of pump depth Xp and commanded casing fluid level command Xcc are known. More specifically, in block 94, the pump speed required to produce the pressure required by the head pressure command Hpc is calculated by multiplying the rated speed Ur by the square root of the ratio of the head pressure command Hpc to the head pressure at rated speed Hre to yield the motor speed feedforward command Umf. The value of head pressure at rated speed Hre is calculated by block 65 of FIG. 5 or block 265 of FIG. 6 depending on the specific embodiment. Fluid Level Feedback Controller Reference is now made to FIG. 9, which is a block diagram of a fluid level feedback controller 100 for the motor vector controller 130. The fluid level feedback controller 100 includes a PID (proportional, integral, derivative) function that responds to errors between casing fluid level command Xcc and casing fluid level Xce to adjust the speed command for the pump 32. Operation of the fluid level feedforward controller 90 provides a command based on the projected operation of the system. This assures that the errors to which the fluid level feedback controller 100 must respond will only be the result of disturbances to the system. The inputs to the fluid level feedback controller 100 include casing fluid level command Xcc and a casing fluid level value Xce. The fluid level command Xcc is a known value and is subtracted from the casing fluid level value Xce in block 101 to produce the error signal Xer for the fluid level feedback controller 100. The algorithm of the fluid level feedback controller 100 uses Z-transformations to obtain values for the discrete PID controller. The term Z−1 (blocks 102 and 109) means that the value from the previous iteration is used during the current iteration. More specifically, in summing block 101, an error signal Xer is produced by subtracting Xcc from Xce. The speed command derivative error term Udc is calculated by subtracting, in summing block 103, the current Xer value obtained in block 101 from the previous Xer term obtained from block 102 and multiplying by the derivative gain Kd in block 104. The speed command proportional error term Upc is calculated by multiplying the proportional gain Kp in block 105 by the current Xer value obtained in block 101. The speed command integral error term Uic is calculated by multiplying the integral gain Ki in block 106 by the current Xer value obtained in block 101 and summing this value in block 107 with the previous value of Uic obtained from block 109. The output of summing block 107 is passed through an output limiter, block 108, to produce the current integral error term Uic. The three error terms, Udc, Upc and Uic, are combined in summing block 110 to produce the speed command Ufc to be summed with the motor speed feedforward command Umf in summing block 79 (FIG. 3 and FIG. 4) for the motor vector controller 130. Vector Controller Reference is now made to FIG. 10, which is a simplified block diagram of the motor vector controller 130. The motor vector controller 130 contains functions for calculating the velocity error and the torque necessary to correct it, convert torque commands to motor voltage commands and current commands and calculate motor torque and speed estimates from measured values of motor voltages and motor currents. In one embodiment, the stator flux is calculated from motor voltages and currents and the electromagnetic torque is directly estimated from the stator flux and stator current. More specifically, in block 131, three-phase motor voltage measurements Vmm and current measurements Imm are converted to dq (direct/quadrature) frame signals using three to two phase conversion for ease of computation in a manner known in the art. Signals in the dq frame can be represented as individual signals or as vectors for convenience. The motor vector feedback model 132 responds to motor stator voltage vector Vs and motor stator current vector Is to calculate a measure of electrical torque Tme produced by the motor. In one embodiment, the operations carried out by motor vector feedback model 132 for calculating the electrical torque estimate are as follows. The stator flux vector Fs is obtained from the motor stator voltage Vs and motor stator current Is vectors according to equation (2):Fs=(Vs−Is·Rs)/s (2)Fds=(Vds−Ids·Rs)/s (2A)Fqs=(Vqs−+Iqs·Rs)/s (2B)where Rs is the stator resistance and s (in the denominator) is the Laplace operator for differentiation. Equations (2A) and (2B) show typical examples of the relationship between the vector notation for flux Fs, voltage Vs, and current Is and actual d axis and q axis signals. In one embodiment, the electrical torque Tme is estimated directly from the stator flux vector Fs obtained from equation (2) and the measured stator current vector Is according to equation (3) or its equivalent (3A):Tme=Ku·(3/2)·P·FsxIs (3)Tme=Ku·(3/2)·P·(Fds·Iqs−Fqs·Ids) (3A)where P is the number of motor pole pairs and Ku is a unit scale factor to get from MKS units to desired units. In one embodiment, rotor velocity Ume is obtained from estimates of electrical frequency Ue and slip frequency Us. The motor vector feedback model 132 also performs this calculation using the stator voltage Vs and stator current Is vectors. In one embodiment, the operations carried out by the motor vector feedback model 132 for calculating the motor velocity Ume are as follows. A rotor flux vector Fr is obtained from the measured stator voltage Vs and stator current Is vectors along with motor stator resistance Rs, stator inductance Ls, magnetizing inductance Lm, leakage inductance SigmaLs, and rotor inductance Lr according to equations (4) and (5); separate d axis and q axis rotor flux calculations are shown in equations (5A) and (5B) respectively:SigmaLs=Ls−Lm^2/Lr (4)then,Fr=(Lr/Lm)·(Fs−Is·SigmaLs (5)Fdr=(Lr/Lm)·(Fds−SigmaLs·Ids) (5A)Fqr=(Lr/Lm)·(Fqs−SigmaLs·Iqs) (5B) The slip frequency Us can be derived from the rotor flux vector Fr, the stator current vector Is, magnetizing inductance Lm, rotor inductance Lr, and rotor resistance Rr according to equation (6): Us = Rr · ( Lm / Lr ) · [ Fdr · Iqs - Fqr · Ids ] Fdr ^ 2 + Fqr ^ 2 ( 6 ) The instantaneous excitation or electrical frequency Ue can be derived from stator flux according to equation (7): Ue = Fds · sFqs - Fqs · sFds Fds ^ 2 + Fqs ^ 2 ( 7 ) The rotor velocity or motor velocity Ume can be derived from the number of motor pole pairs P the slip frequency Us and the electrical frequency Ue according to equation (8):Ume=(Ue−Us)(60)/P (8) In cases where long cable lengths or step up transformers are used, the impedances of the additional components can be added to the model of motor impedances in a method that is known. The velocity controller 133 uses a PI controller (proportional, integral), PID controller (proportional, integral, derivative) or the like to compare the motor speed Ume with the motor speed command Umc and produce a speed error torque command Tuc calculated to eliminate the speed error. The speed error torque command Tuc is then converted to motor current commands Imc and voltage commands Vmc in flux vector controller 134 using a method which is known. Referring to FIG. 15, in one preferred embodiment, the pump control system provided by the present invention is software based and is capable of being executed in a controller 50 shown in block diagram form in FIG. 13. In one embodiment, the controller 50 includes current sensors 51, voltage sensors 52, input devices 171, such as analog to digital converters, output devices 172, and a processing unit 54 having associated random access memory (RAM) and read-only memory (ROM). In one embodiment, the storage devices 55 include a database 175 and software programs and files which are used in carrying out simulations of circuits and/or systems in accordance with the invention. The programs and files of the controller 50 include an operating system 176, the parameter estimation engines 177 that includes the algorithms for the pump model 60 (FIG. 5) or pump model 260 (FIG. 6) and the pump system model 80 (FIG. 7), pump controller engines 178 that include the algorithms for fluid level feedforward controller 90 (FIG. 8) and the fluid level feedback controller 100 (FIG. 9), and vector controller engines 179 for the motor vector controller 130 for converting motor current and voltage measurements to torque and speed estimates and converting speed and torque feedforward commands to motor current and voltage commands, for example. The programs and files of the computer system can also include or provide storage for data. The processing unit 54 is connected through suitable input/output interfaces and internal peripheral interfaces (not shown) to the input devices, the output devices, the storage devices, etc., as is known. Optimized Gas Production The production of methane gas from coal seams can be optimized using the estimated parameters obtained by the pump controller 50 (FIG. 3 or FIG. 4) in accordance with the invention. For methane gas production, it is desirable to maintain the casing fluid level at an optimum level. A range for casing fluid level command Xcc is selected to define an optimal casing fluid level for extracting methane gas. This range is commonly referred to as a sweet zone. In one embodiment of the present invention, the selection of the sweet zone is determined by the controller 50 (FIG. 3 or FIG. 4) that searches to find the optimum casing fluid level command Xcc. Since the sweet zone can change as conditions in the well change over time, it can be advantageous to program the controller 50 to perform these searches at periodic intervals or when specific conditions, such as a decrease in efficiency, are detected. In determining the sweet zone, the centrifugal pump intake pressure Ps or casing fluid level Xc is controlled. The centrifugal pump 32 is controlled by the fluid level feedforward controller 90 and the fluid level feedback controller 100 to cause the casing fluid level Xc to be adjusted until maximum gas production is obtained. The casing fluid level command Xcc is set to a predetermined start value. The methane gas flow through outlet 42 at the surface is measured. The casing fluid level command is then repeatedly incremented to progressively lower values. The methane gas production is measured at each new level to determine the value of casing fluid level Xc at which maximum gas production is obtained. The point of optimum performance is called the sweet spot. The sweet zone is the range of casing fluid level above and below the sweet spot within which the gas production decrease is acceptable. However, the selection of the sweet zone can be done manually by taking readings. Improved Pump Energy Efficiency and Operating Range One method to optimize the pump control when operated at low flow and/or efficiency, is to operate using a duty cycle mode to produce the required average flow rate while still operating the centrifugal pump at its most efficient and optimal flow rate point Qo. In this duty cycle mode, the volume of fluid to be removed from the casing can be determined using the fluid inflow rate Qi when the casing fluid level Xc is near the desired level. A fluid level tolerance band is defined around the desired fluid level, within which the fluid level is allowed to vary. The volume Vb of the fluid level tolerance band is calculated from the projected area between the tubing, casing and pump body and the prescribed length of the tolerance band. This volume is used with the fluid inflow rate Qi to determine the pump off time period Toff. When the centrifugal pump is on, the value for casing fluid level Xc is calculated and the fluid level in the casing is reduced to the lower level of the fluid level tolerance band, when the pump is again turned off. The fluid inflow rate Qi is calculated by dividing the fluid level tolerance band volume Vb by the on time period Ton used to empty the band, then subtracting the result from the optimal pump flow rate Qo used to empty the band. The on-off duty cycle varies automatically to adjust for changing well inflow characteristics. This variable duty cycle continues with the centrifugal pump operating at its maximum efficiency over a range of average pump flow rates varying from almost zero to the flow associated with full time operation at the most efficient speed. Use of the duty cycle mode also increases the range of controllable pump average flow by using the ratio of on time, Ton, multiplied by optimal flow rate, Qo, divided by total cycle time (Ton+Toff) rather than the centrifugal pump speed to adjust average flow. This also avoids the problem of erratic flow associated with operating the pump at very low speeds. This duty cycle method can produce significant energy savings at reduced average flow rates as shown in FIG. 16. As can be seen in FIG. 16, the efficiency of the example pump using continuous operation decreases rapidly below about 7.5 gallons per minute (GPM), while the efficiency of the same pump operated using the duty cycle method remains at near optimum efficiency over the full range of average flow. Pump system efficiency is determined by the ratio of the fluid power output to the mechanical or electrical power input. When operated to maximize efficiency, the controller turns the centrifugal pump off when the centrifugal pump starts operating in an inefficient range. In addition, the centrifugal pump is turned off if a pump off condition casing level at the pump intake is detected by a loss of measured flow. For systems with widely varying flow demands, multiple centrifugal pumps, each driven by a separate motor, may be connected in parallel and staged (added or shed) to supply the required capacity and to maximize overall efficiency. The decision for staging multiple centrifugal pumps is generally based on the maximum operating efficiency or capacity of the centrifugal pump or combination of centrifugal pumps. As such, when a system of centrifugal pumps is operating beyond its maximum efficiency point or capacity and another centrifugal pump is available, a centrifugal pump is added when the efficiency of the new combination of centrifugal pumps exceeds the current operating efficiency. Conversely, when multiple centrifugal pumps are operating in parallel and the flow is below the combined maximum efficiency point, a centrifugal pump is shed when the resulting combination of centrifugal pumps have a better efficiency. These cross-over points can be calculated directly from the efficiency data for each centrifugal pump in the system, whether the additional centrifugal pumps are variable speed or fixed speed. Pump and Pump System Protection One method of protecting the centrifugal pump and system components is to use sensors to measure the performance of the system above ground and compare this measurement to a calculated performance value. If the two values differ by a threshold amount, a fault sequence is initiated which may include such steps as activating an audio or visual alarm for the operator, activating an alarm signal to a separate supervisory controller or turning off the centrifugal pump. In one embodiment, a sensor is used to measure the flow in the tubing at the surface Qpm and compare it with the calculated value Qpe. If the actual flow Qpm is too low relative to the calculated flow Qpe, this could be an indication of a fault such as a tubing leak, where not all of the flow through the centrifugal pump is getting to the measurement point. Another method of protecting the pump is to prevent excessive mechanical power input. In one embodiment, the mechanical power input to the pump is calculated by multiplying the speed Ume by the torque Tme. The result is compared to the mechanical input power limit Ple calculated by the pump model (FIG. 5 or FIG. 6). If the limit Ple is exceeded, the torque and speed are reduced to protect the pump. Although exemplary embodiments of the present invention have been shown and described with reference to particular embodiments and applications thereof, it will be apparent to those having ordinary skill in the art that a number of changes, modifications, or alterations to the invention as described herein may be made, none of which depart from the spirit or scope of the present invention. All such changes, modifications, and alterations should therefore be seen as being within the scope of the present invention. |
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summary | ||
abstract | A nuclear reactor control rod with SiC fiber reinforced structure comprises wing sections and a central joint section. Each of the wing sections is a flat plate spreading axially and radially, and includes storage tubes and a wing surface structural member. The storage tubes are arranged in parallel in a flat plane and contain a neutron absorbing member containing the neutron absorbing material. The wing surface structural member is formed by molding of SiC/SiC composite material as to cover surfaces of the storage tubes and formed to have an outward shape of a flat plate. The central joint section and storage tubes are made of SiC/SiC composite material. The central joint section bundles the wing sections together at center. The storage tubes are bundled together with fibers made of SiC or a textile made of SiC. |
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041636899 | abstract | A nuclear fuel cell for use in a thermionic nuclear reactor in which a small conduit extends from the outside surface of the emitter to the center of the fuel mass of the emitter body to permit escape of volatile and gaseous fission products collected in the center thereof by virtue of molecular migration of the gases to the hotter region of the fuel. |
abstract | Provided are a nuclear reactor and an operating method for the reactor. The reactor includes a driving system and a safety system. The safety system includes isolation vessels, heat exchangers, a coolant pipe, and a communication pipe. Fluid is distributed in the safety system according to thermal, pressure, and leak conditions. |
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062401580 | summary | This application claims the benefit of Japanese Applications No. 10-035108, filed in Japan on Feb. 17, 1998, No. 10-037616, filed in Japan on Feb. 19, 1998, and No. 10-037617, filed in Japan on Feb. 19, 1998, all of which are hereby incorporated by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray projection exposure apparatus, and more particularly, to an X-ray projection exposure apparatus which is suitable for transferring a circuit pattern formed on a mask (also referred to as "reticle") onto a substrate, such as a wafer, via a reflective type focusing X-ray optical system using a mirror projection scheme or the like. 2. Discussion of the Related Art Conventionally, in exposure apparatus used for semiconductor manufacture, circuit patterns formed on a mask (photo-mask) used as an object surface are projected and transferred onto the surface of a photosensitive substrate such as a wafer or substrate for forming a mask, etc., via a focusing optical system. The photosensitive substrate is coated with a resist. The resist is exposed with exposing light to form a rest pattern. The resolving power W of the exposure apparatus is determined mainly by the wavelength .lambda. of the exposing light and the numerical aperture NA of the focusing optical system, and is expressed by the following equation: EQU W=k1.lambda./NA (k1:constant) (1) Accordingly, in order to improve the resolving power, it is necessary to shorten the wavelength and/or increase the numerical aperture. Currently, exposure apparatus used in the manufacture of semiconductor devices uses mainly the i-line having a wavelength of 365 nm, and a resolving power of 0.5 .mu.m is obtained at a numerical aperture of about 0.5. Since increasing the numerical aperture is difficult due to various constraints in optical design, it will be necessary in the future to shorten the wavelength of the exposing light. Excimer lasers are examples of exposing light that has a wavelength shorter than the i-line. The wavelengths are 248 nm for the KrF excimer laser and 193 for the ArF excimer laser, respectively. A resolving power of 0.25 .mu.m is obtained in the case of the KrF excimer laser, and a resolving power of 0.18 .mu.m is obtained in the case of ArF. Furthermore, if X-rays with an even shorter wavelength are used as exposing light, a resolving power of 0.1 .mu.m or less should be possible at a wavelength of 13 nm, for example. The main components of the conventional exposure apparatus are a light source, an illumination optical system, and a projection focusing optical system. The projection focusing optical system is constructed from a plurality of lenses or reflective mirrors, etc., so as to focus the mask pattern on the mask onto a substrate, such as a wafer. To obtain a desired resolving power, it is necessary that at least the focusing optical system be essentially free from aberration. If aberration is present in the focusing optical system, the sectional profile of the resist pattern deteriorates, and as a result, adverse effects on the processes following the exposure and/or the problem of image distortion may arise. In the conventional exposure apparatus for manufacturing semiconductor devices or the like, a position detection device (also referred to as "alignment device") is provided so that a resist pattern can be formed at a predetermined position on the wafer with respect to an existing circuit patterns on the wafer. The alignment device detects the positions of the mask and wafer, and the respective detected positions of the wafer and the mask are adjusted by a wafer stage and a mask stage so that a reduced image of the mask pattern is focused at a prescribed position on the wafer. An example of the alignment device is an optical detection device. This type of device detects alignment marks on the wafer by illuminating the marks and detecting the light reflected from the alignment marks through a photo-detector, for example. When the wafer position changes, the signal output from the photo-detector also changes, thereby enabling the detection of the wafer position. Similarly, the position of the mask can be detected by illuminating the alignment marks on the mask with illuminating light, and then detecting the light reflected from the alignment marks through a photo-detector, for example. Such an alignment device can detect the positions of the respective marks on the wafer and the mask with high accuracy. Accordingly, alignment of the mask with respect to the wafer can accurately be performed. In the conventional exposure apparatus, the alignment devices are disposed between the focusing optical system and the wafer and between the focusing optical system and the mask. Furthermore, in the conventional exposure apparatus, a high resolving power can be obtained in the vicinity of the focal position of the projection focusing optical system. Accordingly, the position of the surface of the wafer that is being exposed must be located in the vicinity of the focal position of the projection focusing optical system. The range in the direction of the optical axis in which the projection focusing optical system exhibits a high resolving power is called the "depth of focus(DOF)." The depth of focus, DOF, is determined mainly by the wavelength .lambda. of the exposing light and the numerical aperture NA of the focusing optical system, and is expressed by the following equation: EQU DOF=k2.lambda./NA.sup.2 (k2:constant) (2) For example, if the numerical aperture is 0.5 and the constant K2 is 1 at a wavelength of 365 nm, then the DOF is 1.5 .mu.m. In order to expose the wafer surface while the wafer surface is positioned within the range of the depth of focus, a device for detecting the position of the wafer surface in the direction of the optical axis of the projection focusing optical system (also referred to as "focal point detection device," because the device detects the vertical position of the wafer in order to position the wafer at the focal point) is installed in the exposure apparatus. Through this device, the position of the wafer in the direction of the optical axis is detected, and the position of the wafer in the direction of the optical axis is adjusted by the wafer stage so as to position the wafer surface at an appropriate position within the DOF. FIG. 12 schematically shows an example of such a focal point detection device. The detection scheme illustrated in FIG. 12 is generally referred to as the triangulation method. In this method, wafer 6 is illuminated with illuminating light 91, which is obliquely incident on the wafer 6 through mirror 95, and light 92 reflected from the wafer is detected by a photo-detector 96 through mirror 95. When the wafer position changes, the optical path of the reflected light changes, which in turn changes the position of the reflected light at the photo-detector 96. Thus, by detecting such position changes at the photo-detector 96, the position of the wafer can be measured. A one-dimensional or two-dimensional position detection sensor is used as the photo-detector. Such a focal point detection device is advantageous because the position on the wafer at which the focal point detection device detects the position of the surface (i.e., the position illuminated by detection light) can be set inside the area being exposed or in the vicinity thereof. In the conventional exposure apparatus, the focal point detection device is installed between the focusing optical system and the wafer. FIGS. 13 and 14 are schematic diagrams illustrating examples of conventional exposure apparatus that uses the i- line. This apparatus is constructed mainly from a light source and illumination optical system (not shown in the figures), a stage 15 for holding mask 14, a projection focusing optical system 13, a stage 17 for holding wafer 16, alignment devices 18 and 18' (FIG. 13), and a focal point detection system 18" (FIG. 14). The mask 14 has a mask pattern thereon, which is to be transferred onto the wafer 16 without reduction or with a certain reduction factor. The projection focusing optical system 13 is constructed of a plurality of lenses, etc., in such a way as to focus the image of the mask pattern on the mask 14 onto the wafer 16. The focusing optical system 13 has a field of view, the diameter of which is about 20 mm, and is constructed in such a way as to transfer the mask pattern onto the wafer 16 at once. The alignment detection devices 18 and 18' detects the positions of respective alignment marks on the mask and the wafer. The focal point detection system 18" emits a light beam 91, such as visible light beam, towards the wafer 16 obliquely, and detects the light beam 92 reflected from the surface of the wafer 16. In the conventional exposure apparatus using the i-line or the like, as described above, the projection focusing optical system can be constructed of leases. Accordingly, an optical system with a field of view of 20 mm square or larger can be designed. Thus, it has been possible to expose a desired region (e.g., a region corresponding to two (2) semiconductor chips) at once. On the other hand, in designing a focusing optical system for X-rays in an effort to obtain a higher resolving power, it is found that the field of view needs to be reduced. Therefore, an exposure region as large as that in the above-mentioned exposure apparatus cannot be exposed at once. Accordingly, a scanning method has been proposed. In the scanning method, a semiconductor chip area of 20 mm square or larger can be exposed using a focusing optical system having a small field of view by synchronously scanning the mask and the wafer during exposure. Using such a method, it is possible to expose the desired exposure region by an X-ray projection exposure apparatus. For example, in the case of exposure by X-rays having a wavelength of 13 nm, it is possible to form the exposure field of view of the projection focusing optical system to be an annular band shape so that a high resolving power can be obtained. FIGS. 15 and 16 schematically show examples of proposed designs of X-ray projection exposure apparatus. The X-ray projection exposure apparatus includes an X-ray source 1, a X-ray illumination optical system 2, a stage 5 for holding a mask 4, an X-ray projection focusing optical system 3, and a stage 7 for holding a wafer 6. The mask 4 has a mask pattern thereon, which is to be transferred onto the wafer 6 without reduction or with a certain reduction factor. The projection focusing optical system 3 includes a plurality of reflective mirrors 31-34, etc., in such a way as to focus the mask pattern on the wafer 6. The focusing optical system has an annular band shape field of view so as to transfer a portion of the mask pattern on the mask 4 having an annular band shape onto the wafer 6. During exposure, the mask 4 is illuminated with X-rays 91, and the reflected X-rays 92 are guided towards the wafer 6 via the X-ray projection focusing optical system 3. The mask 4 and wafer 6 are synchronously scanned with the X-rays at respective constant speeds to expose an entire predetermined region (e.g., a region corresponding to one semiconductor chip). In this example of X-ray projection exposure apparatus, due to various constraints to the design of X-ray optical systems, the reflective mirror closest to the wafer (mirror 34 in FIG. 15 or mirror 31 in FIG. 16) needs to be disposed in proximity to the wafer. Accordingly, it is difficult to install the optical systems for alignment devices and the focal position detection device between the focusing optical system and the wafer. In this connection, the following two problems are worth noting. (1) If the position of the reflective mirror closest to the wafer among the reflective mirrors of the focusing optical system is removed from the wafer in order to increase the gap between the wafer and the closest reflective mirrors, the focusing performance of the focusing optical system suffers, and as a result, the desired pattern with a sufficient resolution cannot be obtained. (2) If the reflective mirror closest to the wafer among the reflective mirrors of the focusing optical system is made thinner in order to increase the gap, the rigidity of such a mirror drops, making manufacture of a high-precision mirror difficult. Thus, in the design of the X-ray exposure apparatus, it is difficult to increase the gap between the mirror closest to the wafer and the wafer without sacrificing the optical characteristics of the focusing optical system. Furthermore, because no operational X-ray projection apparatus has yet been developed, there is no specific proposals as to the arrangement of the above-mentioned focal point detection system (system for detecting the position of the wafer surface in the optical axis direction). SUMMARY OF THE INVENTION Accordingly, the present invention is directed to an X-ray projection exposure apparatus that substantially obviates the problems due to limitations and disadvantages of the related art. An object of the present invention is to provide an X-ray projection exposure apparatus in which alignment detection can be accomplished without sacrificing the optical characteristics of the focusing optical system. Another object of the present invention is to provide an X-ray projection exposure apparatus in which focal point detection can be accomplished without sacrificing the optical characteristics of the focusing optical system. Additional features and advantages of the invention will be set forth in the description that follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the present invention provides an X-ray projection exposure apparatus, including an X-ray source that generates X-rays; a mask stage configured to hold a mask having a mask pattern; an X-ray illumination optical system that directs the X-rays generated by the X-ray source towards the mask; a substrate stage configured to hold a substrate; an X-ray projection focusing optical system that receives the X-rays from the mask and projects and focuses an image of the mask pattern onto the substrate, the X-ray projection focusing optical system including a plurality of reflective mirrors that reflect X-rays, the reflective mirror closest to the substrate stage being adjacent the substrate stage; and a position detection optical system that optically detects a position of the substrate, wherein the X-ray projection focusing optical system is configured to accommodate at least a portion of the position detection optical system. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. |
047611278 | abstract | A drum to receive waste, in particular radioactive waste, and an encapsulating material such as cement is located on a vibratable platform beneath a charge chute. The platform is mounted on an inflatable support, conveniently a plurality of air cushions, operable to lift and maintain the drum in sealing engagement about the charge chute during filling of the drum. Vibration means on the platform vibrate the drum and its contents without breaking the sealing engagement. |
053902190 | claims | 1. Device for trapping migrating bodies within the secondary circuit of a steam generator of a nuclear electric power generating installation, constituted by a filtering system positioned across the annular cross-section of the secondary circuit, downstream of the intake tubes (4) for the water into the secondary circuit and upstream of the entry of the water into the tube bundle (3) of the primary circuit, the tubes of the tube bundle (3) being spaced by a given distance, the filtering system being constituted by grids (16) having meshes with a maximum width smaller than said given distance so as to only allow the passage only of migrating bodies or objects liable to jam between the tubes, said grids having a thickness (E) sufficient to give said grids (16) adequate mechanical strength for resisting stresses such as the weight of operators, hydraulic stresses in both normal and emergency operation mad local impacts of migrating bodies without deformation or fracture. 2. Device according to claim 1, wherein the grids (16) are constituted by circular sectors mounted on two radial brackets (19) common to two adjacent sectors and welded to an envelope (8) of the tube bundle. 3. Device according to claim 2, wherein the grids (16) are screwed to said brackets (19) so as to be dismantlable. 4. Device according to claim 1, wherein the grids (16) are slightly narrower than the annular cross-section of the secondary circuit, at the point where the grids (16) are positioned, so as to leave a clearance (20) to permit expansion between a pressure envelope (7) and an envelope (8) of the tube bundle of the steam generator. 5. Device according to claim 4, comprising first outer strips (21) placed on the outer periphery of the grids (16), in order to prevent the reintroduction by secondary water of migrating bodies trapped on the grids (16) into file outer circular clearance (20) between the grids (16) and file pressure envelope (7). 6. Device according to claim 4, comprising inner strips (22) placed between the grids (16) and the outer surface (17) of the tube bundle envelope (8). 7. Device according to claim 4, comprising second outer strips (30) fixed to the inner face (18) of the pressure envelope (7) of the steam generator in the annular section (14) in order to fill the outer annular clearance (20) between the grids (16) and the pressure envelope (7). |
abstract | A laboratory device unit (1) for processing or analyzing substances, mixtures or media, is provided having functional elements provided in or on a laboratory device (3) for carrying out said processing and/or analyzing. At least two remote controls (2, 6) are provided, wherein a range of functions of the functional elements can be used to a lesser extent with the one remote control (6) than with the other remote control (2). |
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description | An overview of the apparatus of the present invention is depicted in FIG. 1. The IR source 1 is comprised of a catalytic assembly 10, which radiates when contacted by a first fluid 15, positioned within an exit 17 of a housing 5. Housing 5 is depicted in two parts to more clearly show that catalytic assembly 10 is positioned within exit 17 of housing 5. It should further be understood that there can be multiple exits 17 each with a catalytic assembly 10 positioned therein. The catalytic assembly 10 is comprised an element 50 with a catalyst 51 positioned thereon. The catalytic assembly 10 can be made from a single element or a plurality of elements. The entrance 16 of housing 5 is adapted to be connected to the source of first fluid 15, in this case the exhaust port of an internal combustion engine. The first fluid 15 enters the housing through entrance 16 and is directed through catalyst assembly 10 then out exit 17. The housing 5 comprises an exterior surface 19 with a partition 35 extending outwardly therefrom. The partition 35 is positioned such that a second fluid 8 flowing toward the downstream face 11 of catalytic assembly 10 will be deflected away from the downstream face 11. Within housing 5, baffle 30 is positioned outwardly from the interior surface 18 to direct the first fluid 15 flow toward catalytic assembly 10. FIG. 2 shows the apparatus of FIG. 1 mounted on a target 60, in this case an aerial drone. The apparatus is connected to an engine 61.such that the first fluid 15, in this case the exhaust from the engine, causes the catalytic assembly to radiate. Catalytic assembly 10 is positioned in the exit 17 such that the generated radiation 75 is visible to a distant observer 70. FIG. 2 also shows that the engine 61 is integrated into the propulsion system, attached to a propeller 62, of the target 60. FIG. 3 shows another view of target 60 to illustrate that multiple catalytic assemblies 10 can be employed. FIG. 4 shows a schematic representation from the distant observer""s perspective. The device is intended as an IR source that can be acquired by a sensor that is part of a weapon (not shown). The sensor is manipulated by the distant observer 70. Thus an irradiance 71 at the location of the sensor, assumed to the distant observer 70, must be sufficient for the sensor to detect. Thus an irradiance 71 at the location of the sensor, assumed to the distant observer 70, must be sufficient for the sensor to detect. The catalytic assembly 10 is comprised of at least one element 50 with a catalyst 51 positioned thereon. As those skilled in the art will recognize, there are numerous structures for element 50 as well as numerous catalyst for catalyst 51 and still further numerous ways of positioning the catalyst on the element. Element 50 must be capable of radiating, elements providing greater emissivty are preferred. In the case of the present invention, a metallic, short channel element, woven metal 10xc3x9710 mesh constructed of Haynes 230, was used. Other element structures such as expanded metal, gauze, foam, or monolith constructed of almost any material including metals or ceramics could be used. It is preferred that the shape of the material chosen for element 50, or most downstream element 50 in the case where multiple elements 50 are employed, provide a radiation pattern off the downstream face 11 in more than a single direction. An element 50 is comprised of members 52, in this case wire woven into a mesh. Wire has a round cross-section that generates a hemispherical radiating pattern off the downstream face 11. If the shape of the members at the downstream face were planar, a typical monolith, the members 52 would generate a radiation pattern in a single direction. It would be possible, however, to use members 52 with cooperating planer surfaces to generate a multidirectional radiation pattern. For example, two planar surfaces oriented at an acute angle to one another. Depending upon the element chosen and the application, a single or multiple element catalytic assembly might be devised. The most downstream surface of the most downstream element 50, based on the flow of the first fluid through the catalyst assembly, is defined as the downstream face 11. In the case of a multiple element 50 catalytic assembly, it is preferred that the members 52 of respective elements 50 be offset to one another relative to the flow of the first fluid 15 through the catalytic assembly. The catalyst 51 is application dependent, depending upon the composition and operating conditions of the first fluid 15 in combination with the weapon sensor and the range on which the target will be used. The catalyst must be positioned on the element, or elements, such that the catalytic assembly 10 when contacted with the first fluid 15 radiates. Positioning could be accomplished through any number of commonly used deposition techniques or integrated into the composition of the element. In the case of the present embodiment wherein the first fluid 15 is the exhaust gas of an internal combustion engine, any precious metal catalyst, such as platinum or palladium, could be used. While this embodiment depicts the first fluid 15 as an exhaust gas of an internal combustion engine, this should not be considered a limitation of the invention. It is preferred that the invention utilize a first fluid 15 that is presently available onboard the target, the exhaust gas or a fuel. The present invention, however, will function as intended if the first fluid is ancillary to the target, for example a bottled fuel. In addition, it is anticipated that other engines, other than internal combustion, may be used to generate the second fuel 15. The housing 5 is the structure that holds the catalytic assembly 10 in the housing""s exit 17. The design of exit 17 is application dependent, but it is preferred that the opening be sized to permit the maximum exposure of the catalytic assembly 10 downstream face 11 to a distant observer. It should be realized, that the housing can be adapted to the first fluid source with multiple entrances 16. The material selected for the housing is application dependent. A partition 35 extends outwardly from the housing 5 exterior surface 19. Where the target is moving, such as in the depicted aerial drone, the catalyst assembly 10 could be cooled by a second fluid 8 passing over the surface. It is preferred that the partition 35 be located upstream of the downstream face 11, relevant to the flow of fluid 8, to prevent as much as possible this cooling effect, in the presented embodiment thereby defining a partition angle 36 that is acute. The partition 35 also has an overhang 9 that extends beyond the width of the downstream face 11 to account for non-parallel second fluid 8 flow patterns. When the housing 5 is adapted to be in fluid communication with the source of the first fluid, the passage created by the housing may have turns. In order to assure maximum utilization of the catalyst 51, it is preferred that the first fluid be distributed equally throughout the catalyst assembly 10. In the present embodiment, baffle 21 extends outwardly from the interior surface 18 of housing 5 to accomplish this objective. When baffle 21 is performing this function, as depicted in this embodiment, it is preferred that the baffle in cooperation with the downstream face define a baffle angle 22 that is acute. Baffle 21, however, might be employed to simply reduce the pressure drop between entrance 16 and exit 17. The shape and positioning of the baffle is based on the application, but in the preferred embodiment that baffle was given a fair surface and the surface was given a parabolic shape. In the method of the present invention, the catalytic assembly 10 is engineered such that the catalyst 51 cooperates with the first fluid 15 to create a radiation 75. The amount of radiation 75 required is dependent upon the sensor being used and the parameters of the range such as distance from sensor, which is illustrated herein as the distance from observer 70 to the target. The first fluid can either by a fluid onboard the target, exhaust gas or fuel, or from an ancillary source added to the target. To provide additional benefit to the observer by illuminating the target from multiple perspectives, multiple exits 17 each with a catalyst assembly 10 can be positioned at different locations on the target. |
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053352521 | description | DESCRIPTION OF PREFERRED EMBODIMENT Referring now to the drawing FIG. 1, a schematic arrangement of a heat removal system in accordance with the present invention for transferring heat from a reactor gas coolant to a secondary fluid medium is indicated generally. Although the heat removal system finds particular application as a heat removal system in a high temperature gas cooled reactor, utilizing water and steam as the secondary fluid medium, it will become apparent herein that the inventive concept may be employed in other applications with other fluid media. In the illustrated embodiment the non-nuclear portion of the heat removal system is shown as being placed in a lower pit area 10 in close proximity to the nuclear pressure vessel 12 which contains the nuclear portions of the heat removal system, the reactor core (not shown) and other nuclear components (not shown). The nuclear pressure vessel 12 may be of steel or prestressed concrete construction. More particularly, the nuclear portion of the heat removal system is housed within a nuclear steam generator cavity 14 defined internally of the nuclear pressure vessel 12. Turning now to a more detailed description of the heat removal system in acordance with the present invention, and referring to FIG. 1 the nuclear portion of the heat removal system is relatively compact and thus enables the nuclear steam generator cavity 14 within the nuclear pressure vessel 12 to be located below a transverse reactor gas coolant inlet duct 16 which conventionally communicates with the lower end of the core cavity (not shown) for removing reactor gas coolant therefrom. The nuclear steam generator cavity 14 is a generally cylindrical configuration and has a suitable metallic shield liner 18 establishing the outer peripheral surface of the cavity 14 and to which is suitably attached a thermal barrier 20 in a known manner. Within the nuclear steam generator cavity 14 of the nuclear pressure vessel 12 the steam generator is comprised of the reheater tube bundle 22 and the main steam tube bundle 24 which are arranged within a metallic shroud 26 the upper end of which serves as a flow guide 26a to direct reactor gas coolant to the inlet of the reheater tube bundle 22, while the lower portion of the shroud 26b immediately surrounding the reheater tube bundle 22 and the main steam tube bundle 24 is of double wall construction to reduce heat transfer through the shroud 26b. The reheater tube bundle 22 is above the main steam tube bundle 24 which is comprised of the initial superheater stage 24a above and the economizer/evaporator stage 24b below. The reheater tube bundle is comprised of a plurality of heat transfer tubes arranged such that internal steam flows in parallel tube circuits which are connected by reheater lead-in tubes 28 to the reheater inlet penetration 30 in the nuclear pressure vessel 12, and by reheater lead-out tubes 32 connected to the reheater outlet penetration 34 in the nuclear pressure vessel 12. The main steam tube bundle 24 within the nuclear pressure vessel 12 is also comprised of a plurality of heat transfer tubes which are arranged such that internal water and steam flows in parallel tube circuits connected by economizer/evaporator lead-in tubes 36 to the economizer/evaporator inlet penetration 38 in the nuclear pressure vessel 12, and by initial superheater lead-out tubes 40 to the initial superheater outlet penetration 42 in the nuclear pressure vessel 12. Outside of the nuclear pressure vessel 12 the non-nuclear portions of the heat removal system are located in the lower pit area 10. The finishing superheater tube bundle 44 is contained in the finishing superheater pressure vessel 46 which is located adjacent to the nuclear pressure vessel 12 such that the length of the shell side inlet pipe 48, which carries maximum temperature shell side steam from the reheater tube bundle outlet penetration 34 in the nuclear pressure vessel 12 to the finishing superheater shell side inlet penetration 50 is minimized. Shell side steam flows from the finishing superheater shell side inlet penetration 50 through the finishing superheater tube bundle 44 and exits from the finishing superheater pressure vessel 46 through the finishing superheater shell side outlet penetration 52. Shell side steam flow continues through the shell side connecting pipe 54 and enters the intermediate superheater pressure vessel 56 through the intermediate superheater shell side inlet penetration 58, flows through the intermediate superheater tube bundle 60, to exit from the intermediate superheater pressure vessel 56 through the intermediate superheater shell side outlet penetration 62. Shell side steam flow continues through the reheat turbine inlet pipe 64 to deliver power to the reheat turbine 66, and then continues through the reheat turbine outlet pipe 29 to the plant condenser (not shown). Tube side steam from the initial superheater outlet penetration 42 in the nuclear pressure vessel 12 flows through the tube side inlet penetration 70 in the intermediate superheater pressure vessel 56, continues through the intermediate superheater tube bundle 60, and exits from the intermediate superheater pressure vessel 56, through the intermediate superheater tube side outlet penetration 72. Tube side steam then flows through tube side connecting pipe 74 to enter the finishing superheater pressure vessel 46 through the finishing superheater tube side inlet penetration 76, flows through the finishing superheater tube bundle 44, to exit from the finishing superheater pressure vessel 46 through the finishing superheater tube side outlet penetration 78. Steam flow continues through the main steam turbine inlet pipe 80 to the main steam turbine 82, to which it delivers power, and returns through the main steam turbine outlet pipe 98 to the reheater tube bundle inlet penetration 30 in the nuclear pressure vessel 12 for reheating. A water recirculation system is provided to produce satisfactory water velocities in the economizer/evaporator tube bundle stage 24b during low load and start-up operation. In this system water is received from the tube side inlet pipe 68 at the intermediate superheater pressure vessel 56 tube side inlet, passed through heat exchanger 17 to condense excess steam and reduce water temperature to meet recirculation pump 84 requirements, is then circulated by the recirculation pump 84 to mixing tee 86 where recirculated water is mixed with feedwater flow from the plant feedpump (not shown) coming through feedwater pipe 31. Mixed flow continues from the mixing tee 86 to the economizer/evaporator inlet penetration 38 in the nuclear pressure vessel 12. A bypass system is also provided to divert excess flow from the tube side inlet pipe 68 at the intermediate superheater pressure vessel 56 tube side inlet, through the bypass pipe 96 and the pressure reducing valve 94, to the flash tank 92. Excess flow occurs because minimum water velocity requirements in the main steam tube bundle 24 may result in main steam flow above that required to operate the main steam turbine 82 during low load and start-up operation of the plant. Water and steam are separated in the flash tank 92, water being drained through flash tank drain pipe 26 to the plant condenser (not shown), and low pressure steam being diverted through the flash tank steam outlet pipe 23 and the flash tank steam outlet valve 25 to the main steam turbine outlet pipe 98 for return to the reheater tube bundle 22 during plant start-up. Low pressure steam from the flash tank 92 may also be used for hot restarts and other start-up purposes. The by-pass system also serves as a pressure relief system. A main steam diverting pipe 19 is also provided to deliver low temperature superheated steam from the tube side inlet pipe 68 at the intermediate superheater pressure vessel 56 inlet to plant feedwater heaters (not shown). Diverting a portion of the main steam flow to feedwater heaters during continuous plant operation increases the ratio of reheat steam flow to main steam flow through the intermediate superheater tube bundle 60 and the finishing superheater tube bundle 44, thereby reducing the maximum steam temperature requirement at the reheater tube bundle 22 outlet. In briefly reviewing the operation of the steam generator of the present invention, hot reactor gas coolant which during maximum continuous operation may be up to 1600 degrees F. ,at a pressure of approximately 700 psia. and flow rate of between 3 and 6 lb./sec.sq.ft., enters the nuclear steam generator cavity 14 from the reactor gas coolant inlet duct 16, passes into the open top of the flow guide portion of the shroud 26a, flows downwardly through the reheater tube bundle 22, then through the main steam tube bundle 24, and radially through the space between the bottom face of the main steam tube bundle 24 and the thermal barrier 20 on the lower surface of the nuclear pressure vessel 12. The reactor gas coolant, now at substantially lower temperature then passes upwardly within a generally annular flow area between the outer surface of the double wall portion of the shroud 26b and the thermal barrier 20 on the inner surface of the nuclear pressure vessel 12, then outwardly through the annular space 15 for return to the reactor core (not shown), it being understood that flow of reactor gas coolant is effected by a gas circulator (not shown). As the reactor gas coolant passes downwardly within the shroud 26, reheat steam enters reheater inlet penetration 30 in the nuclear pressure vessel 12 simultaneously with feedwater entering the economizer/evaporator inlet penetration 38 in the nuclear pressure vessel 12 during continuous operation of the plant. The reheat steam, which is coming from the main steam turbine outlet pipe 98, is at a temperature of approximately 575 degrees F.,flow rate of approximately 300 lb./sec.sq.ft. and pressure of approximately 700 psia. The feedwater is at an inlet temperature of approximately 350 degrees F., flow rate of approximately 400 lb./sec.sq.ft. and pressure of between 2800 and 4000 psia. The entering reheat steam passes upwardly in series through the reheater lead-in tubes 28 and the reheater tube bundle 22, while feedwater passes upwardly in series through the economizer/evaporator lead-in tubes 36, the economizer/evaporator tube bundle stage 26b and the initial superheater tube bundle stage 24a. During such upward passage within the reheater tube bundle 22, which is arranged in counterflow with respect to the reactor gas coolant flow, reheat steam increases in temperature to between 1300 and 1500 degrees F. by heat transfer from the downwardly flowing reactor gas coolant, the temperature of which is reduced to approximately 850 degrees F. upon reaching the lower end of the reheater tube bundle 22, continuing downwardly to enter the main steam tube bundle 24. Simultaneously during similar upward passage of feedwater within the economizer/evaporator tube bundle stage 24b and the initial superheater tube bundle stage 24a, which are arranged in counter flow with respect to the reactor gas coolant flow, the feedwater undergoes a phase change to superheated steam emerging at the top of the main steam tube bundle 24 at a temperature of approximately 750 degrees F. The phase change and temperature increase is effected by heat transfer from the downwardly flowing reactor gas coolant which is emerging from the reheater tube bundle 22. The temperature of the reactor gas coolant is reduced to approximately 500 degrees F. upon reaching the lower end of the main steam tube bundle 24. Reheat steam exiting from the reheater tube bundle 22 passes downwardly through the reheater lead-out tubes 32 and through the reheater outlet penetration 34 in the nuclear pressure vessel 12 where tube to tube differences in temperature are dissipated by mixing. Similarly superheated steam which is exiting from the initial superheater tube bundle stage 24a passes downwardly through the initial superheater lead-out tubes 40 and through the initial superheater outlet penetration 42 in the nuclear pressure vessel 12 where tube to tube differences in temperature are dissipated by mixing. The intermediate superheater pressure vessel 56 and the finishing superheater pressure vessel 46 which ape located outside of the nuclear pressure vessel 12 contain respectively, the intermediate superheater tube bundle 60 and the finishing superheater tube bundle 44, which produce an increase in temperature of superheated steam emerging from the initial superheater tube bundle stage 24a, by regenerative heat transfer from high temperature excess heat which is available in the shell side reheat steam flow. The reheat steam exiting from the nuclear pressure vessel 12, which during maximum continuous operation is at a temperature of between 1300 and 1500 degrees F., a flow Pate of approximately 300 lb./sec.sq.ft. and a pressure of approximately 700 psia flows downwardly in shell side inlet pipe 48 where tube to tube temperature differences which developed in the reheater tube bundle 22 are dissipated by mixing, to enter the finishing superheater pressure vessel 46 shell side through the finishing superheater shell side inlet penetration 50. Shell side reheat steam then flows transversely across the finishing superheater tube bundle 44, which is arranged in counterflow with respect to shell side reheat steam flow and tube side main steam flow, and exits from the finishing superheater pressure vessel 46 through the finishing superheater shell side outlet penetration 52 where it enters the shell side connecting pipe 54 from which shell side reheat steam flow continues into the intermediate superheater pressure vessel 56 through the intermediate superheater pressure vessel shell side inlet penetration 58. Shell side reheat steam flow then flows transversely across the intermediate superheater tube bundle 60 which is arranged in counterflow with respect to shell side reheat steam flow and tube side main steam flow before exiting from the intermediate superheater pressure vessel 56 through the intermediate superheater shell side outlet penetration 62 at a temperature of approximately 950 degrees F. As reheat steam flows through the shell side of the intermediate superheater tube bundle 60 and the finishing superheater tube bundle 44, main steam flow from the initial superheater tube bundle stage 24a passes downwardly through the initial superheater outlet penetration 42 in the nuclear pressure vessel 12, and downwardly through the intermediate superheater pressure vessel tube side inlet pipe 68 where tube to tube temperature differences which developed in the main steam tube bundle are dissipated by mixing, to split into two flow streams in which a flow of approximately 450 lb./sec.sq.ft. at a temperature of approximately 750 degrees F. and pressure of between 2800 and 4000 psia, continues into the intermediate superheater pressure vessel 56 through the intermediate superheater tube side inlet penetration 70, while a flow of approximately 50 lb./sec.sq.ft. at a temperature of approximately 750 degrees F. and pressure of between 2800 and 4000 psia. enters the main steam diverting pipe 11 continuing on to plant feedwater heaters (not shown). Main steam flow of approximately 450 lb./sec.sq.ft. continues through the tube side of the intermediate superheater tube bundle 60 which is arranged in counterflow with respect to shell side reheat steam flow and tube side main steam flow, and exits from the intermediate superheater pressure vessel 56 through the intermediate superheater tube side outlet penetration 72 where main steam flow enters the tube side connecting pipe 74 in which tube to tube temperature differences which developed in the intermediate superheater tube bundle 60 are dissipated by mixing. Main steam flow then enters the finishing superheater pressure vessel 46 through the finishing superheater tube side inlet penetration 76, flows through the finishing superheater tube bundle 44, and exits from the finishing superheater pressure vessel 46 through finishing superheater pressure vessel tube side outlet penetration 78. During passage through the intermediate superheater tube bundle 60 and through the finishing superheater tube bundle 44 main steam flow attains a temperature of approximately 950 degrees F. and tube to tube temperature differences which developed in the finishing superheater tube bundle 44 are dissipated by mixing in the main steam turbine inlet pipe 80, before reaching the main steam turbine 82. Upon delivering power to the main steam turbine 82, main steam flow at reduced temperature and pressure returns through main steam turbine outlet pipe 98, to the reheat inlet penetration 30 in the nuclear pressure vessel 12. During start-up and low load operation of the plant the recirculation system and the bypass system are in operation to maintain minimum required water velocities, and thereby produce positive upward flow in all of the parallel tube circuits, in the economizer/evaporator tube bundle stage 24b, and the initial superheater tube bundle stage 24a. The recirculation system is operated by opening the inlet valve 88 and the outlet valve 90 while the recirculation pump 84 is running. The recirculation pump inlet heat exchanger 17, inlet valve 88 and outlet valve 90 are adjusted to provide a minimum flow rate of 100 lb./sec.sq.ft. at a temperature of approximately 350 degrees F. and a pressure of between 2800 and 4000 psia to the economizer/evaporator inlet penetration 38 in the nuclear pressure vessel 12. Flow in excess of approximately 133 lb./sec.sq.ft. at the initial superheater outlet penetration 42 in the nuclear pressure vessel 12 is diverted to the bypass flash tank 92 during start-up and low load operation of the plant, to maintain feedwater flow between one-quarter and one-third of maximum continuous flow. While a preferred embodiment of the present invention has been illustrated and described it will be understood to those skilled in the art the changes and modifications that may be made therein without departing from the invention in its broader aspects. Various features of the invention are defined in the following claims. |
description | 1. Technical Field The present invention relates generally to a novel method for producing neutrons in a controlled manner in a novel type of neutron generator, and more particularly to a novel method and apparatus for producing commercially and medically useful isotopes by transmuting selected precursor isotopes using gamma radiation. 2. Background Art It is well known that neutrons produce valuable isotopes used in scientific research, manufacturing, and medicine. Radioactive isotopes are employed in scientific research in fields as diverse as hydrology and life sciences. Isotopes are used in business and commerce in many manufacturing process and in the production of oil and gas. The most valuable, yet some of the most difficult to make isotopes, are used in the diagnosis and treatment of human diseases and disorders. It is also well known that fission in nuclear reactors produces fission products that are a component of nuclear waste. Isotopes are currently produced by electron beams, ion beams, in cyclotrons and in nuclear reactors. Some isotopes may be produced by any of the four general methods. Others by one method alone. The science of isotope production involves adding or subtracting the requisite number of nucleons (protons or neutrons) to or from the target's parent isotope to produce the desired end product in significant quantities with appropriate purity. The transmutation reactions that change the number of protons or neutrons in the isotopes include photo nuclear reactions wherein energetic gamma photons eject neutrons from nuclei. Also high energy neutrons are able to displace or eject protons from nuclei. Transmutation reactions caused by accelerated ions such as protons, deuterons, helium nuclei and other ions collide with the nuclei of the target material to change the isotope from one to another. These reactions generally do not yield the quantity of desired product material as efficiently as reactions involving successive or singular neutron capture in the nuclear reactor. The above mentioned reactions also are not as efficient in the treatment of fission products to transmuted them to shorter lived isotopes or common stable isotopes. The present invention relates to an inventive compact neutron generator and isotope production apparatus and method of using the apparatus to produce copious amounts of commercially and medically useful neutrons. The gamma,n reaction produces the neutrons in beryllium and deuterium as well as high-Z materials such as bismuth, lead, thorium and uranium. The produced neutrons from gamma n reactions are moderated or their spectrum is shaped so that the capture of neutrons in the target isotope is maximized. The present invention advances the art by employing alloys fashioned from materials that emit energetic gamma radiation to obviate the use of a reactor or a cyclotron for these applications when stimulated by high energy electrons. The novel method disclosed herein takes advantage of the energetic gamma radiation emitted from isotopes of nickel, vanadium, iron and other high gamma emitting materials after one or successive neutron captures or from gamma,n reactions on high-z materials such as bismuth, lead, thorium and uranium. For the purpose of this application the thermal energy region is defined as 1/1000 electron volts to 5/10 electron volts, the epi thermal energy region as 5/10 electron volts to 5000 electron volts, the fast energy region as five thousand electron volts (five kilo electron volts, 5 keV) to one million electron volts (1 MeV) and the high energy region as above one million electron volts (1 MeV) and in some cases in excess of ten million electron volts (10 MeV). The novel neutron generator of the present invention uses gamma photons to dissociate nuclei of beryllium and/or deuterium or to produce neutrons from bismuth, lead, thorium or uranium. The apparatus is best summarily described as a photo nuclear neutron generator and isotope producer. Using the inventive apparatus, gamma photons are produced in various alloys or compounds of gamma emitting isotopes. Exemplary gamma emitting isotopes that function by neutron capture include, but are not limited to: vanadium-50, vanadium-51, nickel-59, nickel-61, iron-57, iron-54, erbium-167, europium-151 europium-153, gadolinium-155, gadolinium-157, bromine-79, palladium-105, palladium-107, and others being high-z refractory materials such as tantalum, tungsten, rhenium and niobium functioning as a “converter” in which energetic electrons are slowed down and emit penetrating and energy gamma photons. The inventive photo nuclear neutron generator is a very compact “plug-in” neutron generator that obviates the need for large reactors to produce neutrons for several applications and uses including: (1) production of therapeutic medical isotopes and other important isotopes used for the treatment or diagnosis of disease or for the production of other commercially significant isotopes, (2) production of penetrating gamma radiation for industrial applications; (3) production of neutrons for the waste treatment of fission products from spent light water reactor fuel to convert the fission products to shorter lived or stable isotopes; (4)) for motive power applications and (5) the gamma photons can also transmute matter by ejecting neutrons from nuclei to accomplish transmutations with the same results and purpose as the aforesaid four applications and uses. There has thus been broadly outlined the more important features of the invention in order that the detailed description that follows may be better understood, and in order that the present contribution to the art may be better appreciated. Additional objects, advantages and novel features of the invention will be set forth in part in the description as follows, and in part will become apparent to those skilled in the art upon examination of the following. Furthermore, such objects, advantages and features may be learned by practice of the invention, or may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims. Still other objects and advantages of the present invention will become readily apparent to those skilled in this art from the following detailed description, which shows and describes only the preferred embodiments of the invention, simply by way of illustration of the best mode now contemplated of carrying out the invention. As will be realized, the invention is capable of modification in various obvious respects without departing from the invention. Accordingly, the drawings and description of the preferred embodiments are to be regarded as illustrative in nature, and not as restrictive. Referring to FIGS. 1 through 5, wherein like reference numerals refer to like components in the various views, wherein FIG. 1 is a schematic view showing a first preferred embodiment of the neutron generator and isotope production apparatus of the present invention. This view shows that an exemplary embodiment 100 includes an electron beam source 300 which directs an electron beam, preferably 10 mA, between 16 and 32 MeV, to a first chamber, which is a converter cell. The converter cell preferably comprises a hollow rectangular 2 mm tungsten alloy channel or tube 1 with an interior void 2 through which cooling water or other working fluid such as helium, carbon dioxide, or selected liquid metal or alloy of liquid metals as may be continually circulated to export heat and enable long term operation of the system. While tungsten alloy is the preferred alloy material, alloys of other refractory metals, such as rhenium, niobium and or tantalum, or any combination thereof as computationally optimized, may be employed. The electron beam source is separated from the converter cell by dry air 400, which surrounds the two chambers. The system next includes a second chamber 4, which contains one or more target isotopes, and the volume of target isotope may be demised into a plurality of cells 10-13, 20-23, 30-33, 40-43, 50-53, 60-63, 70-73, 80-83, and 90-93, which receive various amounts of exposure to gamma rays at various energies. The energy dependent photon fluence may be calculated for each zone. FIGS. 2-5 show a compound target assembly of a second preferred embodiment of the inventive compact neutron generator and isotope production apparatus of the present invention, showing the target assembly 100, including a central power rod 200, preferably consisting of high-Z x-ray emitting material such as lead bismuth eutectic, and even more preferably spiked with fissile material or neutron multiplying material. This is disposed in an inner tube of spectrum shaping material, preferably a gamma emitting erbium-167-nickel cup 210. The cup may be cooled by heavy water pumped through channels 215, exterior to the cup, as shown. Axially disposed around the inner tube of spectrum shaping material (and preferably spaced apart therefrom) is a ring or tube of precursor isotope target material 220, in either ring, tube, or foil form. This is followed by an outer ring of spectrum shaping alloy 230, and an outer ring of neutron multiplying target material 240 or gamma converting material. An optional reflector 250 may be axially disposed around the outer ring of neutron multiplying target material in order to reflect second generation neutrons back to the target to drive fission reactions. The reflector is preferably fabricated from beryllium, beryllium deuteride, beryllium triteride, or heavy water producing thermalised neutrons. Channels 215, 225, 235, 245, may be disposed around and between each of the material layers and provided with circulated air or heavy water to cool each layer of the target assembly. Alternatively, in embodiments where cooling is either not desired or not needed, the channels may be eliminated and each material layer (ring or tube) disposed immediately upon and approximated to the underlying material layer (ring, tube, or rod). FIG. 5 is a cross sectional end view in elevation of the central neutron generator cavity where the capsule is attached to an electronics package 270, and showing the relative position of gamma generating alloy forming the cup 280 and selected target material 290 for the gamma,n reaction. The gamma emitting assembly of the photo nuclear neutron generator of the present invention has unique design characteristics. There are common elements to the preferred embodiments of the present invention. The first common element is the use of neutron multiplication in by elevating the intensity of cascades of gammas in two or more volumes (200, 240) within the compound target assembly 100 shown in the diagrams and/or figures. The x-ray source is depicted as a tube or rod 200 in the central axis of the cylindrical electron or particle accelerator. The second element common to all of the preferred embodiments is the use of a spectrum shaping gamma emitting alloy disposed proximate the neutron multiplying target. These are “cups” 210 of gamma emitting alloy that “hold” or surround the LBE. These cups are preferably jacketed and cooled by heavy water pumped through a channel 215 that also contributes neutrons to the central area of the target. The gamma emitting alloy 210 includes spectrum shaping additives that soften the high energy spectrum to an epithermal or thermal neutron spectrum as needed to promote the most efficient capture in the selected isotopes comprising the gamma emitting alloy. In the preferred embodiments, the metal matrix for shaping the neutron spectrum is composed of vanadium nickel erbium europium or other selected lanthanide(s) that are computationally optimized. Aluminum has low parasitic neutron absorption cross-section, and nickel has high elastic scattering cross-section. Other metals of the alloy such as vanadium or zirconium have unique neutronic properties so these can be added to improve neutronic behaviors in the spectrum shaping matrix that assists capture in the gamma producing alloy. The hydrogen atoms in the hydrides function to soften neutron spectrum to its optimal shape for transmutations that produce gamma radiation. The metals that form the intermetalic deuteride compounds include yttrium, europium, gadolinium, erbium, ytterbium, zirconium, vanadium, and titanium. Additionally, various oxides are known to shape or tailor neutron spectra. These include zirconia, alumina, and lithia-7. Finally carbide compounds and nitrides as homogeneously dispersed fine particles can be used with the hydrides to assist in slowing neutrons down in aluminum alloys. All of the additives are fine powders that are homogeneously dispersed in the alloy. The photo nuclear neutron generator can be configured to produce more than one medical isotope at a time and can also be used to produce electrical energy. The device can produce many Positron Emission Tomography (PET) Isotopes, various longer lived positron emitting isotopes, and actinium-225 and many other useful isotopes by the gamma,n reaction. Further, long lived fission products, mid Z isotopes can be transmuted to shorter lived isotopes or to stable isotopes as a method of the treatment of nuclear waste using this type of neutron generator/neutron ejector. When the purpose of the inventive neutron generator is to produce useful amounts of electrical energy for motive applications, then the materials interacting with the gammas would be selected to produce gamma,2n reactions to multiply the number of neutrons producing gamma photons. These gammas do not have to be highly energetic so that the selected lanthanides can provide much of the mass of the gamma emitting alloy and the lanthanide such as erbium-167 has a high affinity for neutrons having thermal energies. This apparatus is called the Photo Nuclear Neutron Generator. For this embodiment matter which most easily “ejects” neutrons (beryllium, deuterium, bismuth, lead, thorium, uranium, for example) is illuminated with energetic gamma radiation generated from neutron captures in electron slowing down reactions or from neutron capture in vanadium 50 and 51 nickel 61 or similar isotopes with the selected lanthanides disclosed in paragraph one above. These isotopes have the attribute of emitting energetic gamma photons above the five million electron volt level. These gammas interact with neutron shedding matter to cause a gamma,2n reaction in beryllium and in deuterium or in lead. For the effect to take place in beryllium the incident photon must have energy in excess of 1.67 MeV. For deuterium the energy must be in excess of 2.24 MeV. The cross-section is much higher for the high-z materials such as lead, bismuth, thorium and uranium although the threshold energy must be over 8 or so MeV. These energies are the binding energy for the least bound neutrons in found in nature. Further particle collisions with these materials will also cause neutrons to be produced by the n,2n reaction as well as from the electron generated gamma,n reactions. The novel idea includes the use of gamma emitting isotopes to produce energetic gamma radiation in combination with gamma produced from energetic electrons. The gamma photons are energetic enough to cause neutrons to be ejected from the nuclei of common isotopes, fluorine-19, nitrogen-14 for example to produce positron emitting isotopes, fluorine-18 and nitrogen-13 for example in commercial quantities as well as other valuable isotopes including actinium-225 by means of the gamma,n reaction. The gamma emitting alloy is engineered computationally to slow neutrons down to epithermal energies where captures are most likely in the gamma emitting alloy, containing vanadium-50 and nickel-61 and others like this one that emit energetic photons. The target for the production of isotopes is the selected common isotope and precursor material for each of the desired positron emitting isotopes to be produced. As noted, the spectrum shaping alloy material facilitates efficient neutron capture by the gamma emitting isotope in the selected resonance energy regions. This maximizes the production of the desired gammas of high intensity. The spectrum shaping material can be a hydrided or deuterated alloy or an oxide strengthened alloy or an alloy containing carbides, nitrides or other neutron scattering material that shapes or tailors the spectrum appropriately, each spectrum shaping alloy being specifically formulated to shape or tailor the spectrum to maximize production of gammas in the selected gamma emitting isotope. One particularly effective scattering alloy is composed of very fine particles of boron tetra carbide (B4C) dispersed in aluminum silumen or vanadium-nickel, aluminum zirconium alloys. This scattering alloy functions as a moderator and allows neutrons to be slowed in a controlled manner so that they reach the reduced energy needed for effective capture in the selected gamma emitting isotope. The scattering materials are preferably low Z ceramics boron tetra carbide (B4C) with the boron as boron-11, lithium-7 boride (with the boron as boron-11), lithium-7 nitride, and boron nitride (with the boron as boron-11). These are low-Z materials with low neutron capture and they can be combined with hydrides of zirconium, titanium, vanadium, lithium to provide spectrum softening effects to optimize the spectrum for capture. For increasing the probabilities of the gamma,n reaction, the shaping alloy can be nickel aluminum, Ni3Al, with zirconium hydride. The main alloy matrix employed to produce the gammas is Er3Ni, in which the erbium is erbium-167. Using the inventive method, neutrons can be generated using a high energy electron beam 275 that interacts with a liquid lead bismuth eutectic (LBE). The LBE is either spiked with particles of fissile uranium-233, uranium-235 and/or plutonium-239 alloyed with optimized amounts of beryllium, or it is not spiked with fissile material but is instead alloyed with beryllium. Spiking with fissile material will increase neutron production provided there is sufficient spectrum shaping material present. to moderate the produced neutrons to thermal energies with the highest cross-sections for n, fission reactions. The incident electrons produce energetic x-rays in the gamma ranges of the electromagnetic spectrum from interactions with the high-Z materials comprising the LBE, lead bismuth eutectic that may also contain thorium, uranium and one or more selected fissile isotopes such as uranium-233, uranium-235 or plutonium-239 or plutonium-241. These gammas are energetic enough to photo-dissociate nuclei of beryllium, deuterium and tritium as well as the high-z isotopes of lead bismuth, thorium and or uranium. The first generation neutrons produced from the interactions of the electron beam with the spiked LBE or non-spiked LBE, can be moderated to a thermal spectrum by spectrum shaping alloys, and after moderation are most likely to interact with selected fissile material by neutron capture and fission. Second generation neutrons are produced by fission are energetic and will escape the liquid target area without interacting with the fissile material in the target and without interacting with the LBE. Some of second generation neutrons can be reflected back to the target by the reflector made of beryllium, beryllium deuteride, beryllium triteride, or heavy water producing thermalised neutrons to drive fission reactions in the spiked LBE embodiment. The reflected second generation neutrons become low energy neutrons and will interact with the fissile material in the target with high probability. The reaction set will amplify without becoming critical because the amplification is dependent upon continuous input of gamma radiation from the electron beam, because the fissile mass is non-critical and the geometry is well considered when the mass and density of the selected fissile material(s) in the metal matrix is sufficient. Additional gammas are provided by the interior of the target containing the spiked or unspiked LBE. The part of the target that surrounds the LBE is comprised of erbium-nickel alloy which emits energetic and penetrating gamma radiation in excess of 8 MeV for each neutron captured by each erbium-167 nuclei. This alloy is also an excellent conductor of heat to provide cooling for the LBE. More energetic gammas are provided by the capture in erbium-167 than what is produced by the electron beams. The gammas from erbium-167 are energetic enough to photo-dissociate more than one nuclei of beryllium, deuterium or tritium that may be encountered. Also the erbium-nickel “cup” that holds the LBE has heavy water circulating in it. Heat is generated from the electron beam and from fission in the target. Heat is removed by pumping heavy water through the vanadium-erbium-nickel alloy that functions as the structural material to hold the spiked or unspiked LBE. Since erbium nickel is an excellent conductor of heat and since the working fluid for heat transport is heavy water, D2O, heat is managed well and additional neutrons are produced via gamma,n reactions from the D2O. The heavy water is pumped through the interior element of the target to transport heat to the heat exchanger outside of the apparatus to keep the operating temperature of the neutron generator within satisfactory ranges. Each embodiment of the invention discloses the novel apparatus that produces significant quantities of neutrons outside of the conventional nuclear reactor or neutron generators using fusion reactions of tritium and deuterium, or using alpha emitters on beryllium. The produced neutrons can be used to transmute isotopes using the n,2 reaction, the n,3n reaction and or the gamma,n reaction. Further, significant amounts of gamma radiation for direct conversion to direct current is available. The neutrons or the produced gamma radiation could be used to transmute many unstable isotopes commonly known as “fission products” to shorter lived radioactive isotopes or to stable non-radioactive isotopes. Numerous medical and commercial isotopes, especially the positron emitting isotopes, can be produced using the gamma,n reaction. Energetic gammas eject neutrons from the nuclei of target isotopes to make important future commercial medical isotopes. The gamma photons can produce a usable electric current by the photoelectric effect for direct electrical production in other embodiments. Depending on the application, this device produces neutrons up to 5×1014 (5×10sup.14) neutrons per second with about 250 kilowatts of thermal output that is managed by the cooling system. These neutrons have a different spectrum than the thermal or fast fission spectra. Copious high energy neutrons are produced with a significant population above eight million electron volts (8 MeV). The output of the neutrons can be modulated by changing the pulse rate of the electron beam so that as fewer pulses per second occur, to reduce the neutron production rate. Cooling is achieved by circulating heavy water or other selected coolants through the interior of the target, specifically the vanadium-erbium-nickel alloy that readily absorbs neutrons, conducts heat well and provides high energy gamma radiation in return. The structural components of the target preferably comprise a vanadium-nickel-erbium alloy which transfers heat efficiently and from which energetic and penetrating gamma radiation is produced when neutrons are captured. This gamma radiation is produced from thermal epithermal neutron capture in erbium-167 for the most part. These gammas are energetic enough to photo dissociate neutrons from nuclei of beryllium or deuterium. These photo produced neutrons will be in the thermal spectrum and will cause uranium-233, uranium-235, plutonium-239, or americium-243m to fission. These produce fission spectrum neutrons that are too energetic to cause a chain reaction and they escape from the target compartment(s) containing the selected fissile materials. The embodiments of this neutron generator include transportable devices that are electrically energized; allowing neutron production to cease shortly after the generator's electron beam is de-energized. The first generation neutrons are produced in the target from energetic x-rays above 5 MeV by the displaced electrons in the high-Z, LBE or LBE containing thorium and uranium spikes also with spectrum shaping alloys and computationally optimized amounts of fissile material. Additional neutrons can be produced in a surrounding the sub-critical assembly. The generator will not sustain a nuclear chain reaction because the fissile materials are carefully distributed and are too low of mass to support an uncontrolled chain reaction. The device is activated electrically so that the produced stream of neutrons can be conveniently turned on and off to suit the needs of the application. The electron beam area of the neutron generator consists of an evacuated tube made from a commercially available components. At the top end of the evacuated tube the electrons or alpha particles are gathered, excited and are accelerated by the electronic package to the target. The electrons or alpha ions are accelerated in the evacuated tube by electrostatic field effects, electrical effects and/or magnetic means to a high velocity near 99.99c (99.99% of the speed of light). The energy of the electron beam should be between two and four times the Giant Resonance region of the targeted material for the gamma,n reaction to occur within that material. Beryllium and deuterium have the lowest gamma,n threshold energies known, 1.67 MeV and 2.24 MeV respectively. The Giant Resonance energy region for these reactions in these materials spans energies of 2.0 million electron volts (2.0 MeV) to ten million electron volts (10 MeV). Electrons having a velocity of 99.99c have an energy of ten million electron volts (10 MeV). At the bottom end of the evacuated beam tube, the 10 MeV electron beam interacts with the target matter the selected converter alloy of refractory elements, tantalum, tungsten rhenium and niobium or the beam interacts with high-Z materials, lead, bismuth, thorium and uranium with optimized amounts of selected fissile materials comprising the spiked LBE. In all embodiments there is a subcritical mass, density and geometry when the LBE is spiked with fissile material as set out above in another embodiment and in the preferred embodiment High-Z bismuth lead eutectic is used with out fissile material, with a low Z neutron source materials such as beryllium in the LBE target and deuterium in the heavy water coolant to provide the neutrons in response to the gamma photons produced from the activated electron beam or from the vanadium-50-nickel-58-erbium-167 alloy or from palladium-105 and palladium-107 deuteride in compartments in the target assembly. When alpha particles are used at high enough energy, spallation neutrons are produced from the LBE. These neutrons interact with the gamma emitting alloys. This embodiment of the neutron generator can produce its neutrons from powdered beryllium dispersed in an aluminum “lamp shade” surrounding the exterior of the generator with out the need for the use of fissile materials in the generator. An aluminum clad powdered beryllium “lampshade” would reflect neutrons from the interior to sustain production of energetic gammas in the erbium alloy driving photo-dissociation reactions in the beryllium powder portion of the “lamp shade.” The electronics package 270 contemplates the use of any suitably charged particles: electrons, protons, deuterons and alpha particles, depending on the application and the effectiveness of each charged particle to produce the desired reaction. The target generates the neutrons upon stimulation from bombardment of the relativistic electrons after the electrons are converted to x-rays and after the x-rays interact with deuterium and beryllium. The LBE spiked target is uranium-235, uranium-233 or plutonium-239, plutonium-241 or americium-243, or any combination thereof (as the fissile neutron source) with, beryllium, deuterium or tritium, or a combination thereof (as the non-fissile neutron source) in one embodiment. The target geometry and target mass are calculated computationally, optimized and engineered so that the target assembly and its components are highly sub-critical at all times. The accelerated electrons interact with the high-Z materials, uranium, plutonium or americium to produce energetic x-rays or in the preferred embodiment to produce x-rays in a lead bismuth eutectic. These x-rays are powerful enough to dissociate beryllium nuclei by the gamma,n reaction when the emitted energy is above 1.67 MeV. The target may include a chamber containing beryllium di-deuteride or lithium beryllium tri-deuteride and tri-triteride or palladium deuteride. The gammas produced from the electron beam will dissociate deuterium nuclei (as well as the beryllium nuclei) by the gamma,n reaction when the energy of the gamma is above 2.24 MeV. Higher energy gammas will be produced by capture reactions in the target where neutrons are captured by erbium-167. These gammas exceed 6 MeV which can photo dissociate more than one nuclei of beryllium or deuterium but will interact with high-z materials such as lead, bismuth, thorium and uranium to produce neutrons more efficiently. To recapitulate and further clarify the teaching of this disclosure: There are three energy “generations” for the neutrons produced by the target and four energy “generations” of gammas. The first generation neutrons are produced by the gamma,n reaction as a consequence of the high energy electron beam interacting with the converter material and high-z target such as lead, bismuth, thorium or uranium. The second generation neutrons are produced from fission in one embodiment. The second or third generation neutrons, depending on the presence or absence of fissile material in the target, are from the higher energy gamma,n reactions from erbium, nickel and vanadium acting on high-Z materials, lead, bismuth, thorium and uranium. The gammas are from the electron beam and from neutron capture in erbium, nickel and vanadium. Each has its characteristic wavelength. These gammas cause photo dissociation in the heavy water coolant as well, in compartments containing either beryllium or deuterium and in the exterior beryllium-containing aluminum lampshade. The first generation neutrons, those produced by the incident accelerated particles, have energy in or near the thermal neutron range. These primary neutrons will interact with the nuclei of the fissile materials and will cause the fissile material in the target to fission with known probabilities in one embodiment. The resulting fissioning will produce energetic neutrons and fission fragments. Some of these neutrons will escape from the target and others will interact with the beryllium nuclei to either produce additional neutrons or will be thermalised to be captured by fissile materials and cause fission with a K eff below 1. The liquid metal alloy comprising the beam target is electrically conductive so that the electron beam can be maintained indefinitely. The LBE target is arrayed like a wick inside a candle made from thoria-containing zirconium hydride or other refractory material. The tube of electrically insulating material surrounds the target at the down end of the evacuated tube and the down end comprised of the vanadium-nickel-erbium alloy that holds the liquid metal LBE, as if it were a deep cup. The target is cooled by circulating heavy water through the deep cup comprising the gamma emitting alloy. This provides for the production of gammas boosting the yield from the electron input. The deuterium in the coolant circulating through the deep cup provides additional neutrons from the gamma,n reactions. These neutrons will be captured by erbium in the target to produce energetic gamma photons sufficient to effectively dissociate nuclei of deuterium and beryllium positioned outside of the target. These materials “shed” neutrons when exposed to high energy gamma radiation. The “shed neutrons” are the product of the generator and escape the target area. These can be captured by a covering of gamma emitting isotopes for the production of medical isotopes placed outside of the beryllium lampshade. If power is to be produced, the covering of gamma emitting isotopes is, in turn, covered by photo electric materials that produce a direct current from the gamma photons like cadmium-tellurium, cadmium zinc tellurium, cesium iodide thallium plus silicon. A different embodiment of the neutron generator is used for the production of commercial or medical isotopes by the use of the gamma,neutron reaction. The generator neutrons are captured outside of the target by the gamma emitting target comprised of isotopes such as vanadium-50 vanadium-51, nickel-58 and nickel-61 and erbium-167 that emit energetic and penetrating gamma radiation when neutrons are captured. These alloys are placed in close proximity to target isotopes and the transmutation reactions result as the gamma photons interact with nuclei of the target isotope by causing neutrons to be ejected from the nuclei of the targets. All of the preferred embodiments of the neutron generator of the present invention employ isotopes that have large capture cross sections for neutrons and emit very energetic gamma photons. These include vanadium isotopes, vanadium-50 and vanadium-51 nickel isotopes, nickel-59 and nickel-61, the iron isotopes iron-57 and iron-54, europium isotopes europium-152 and europium-154, erbium isotopes including erbium-167, gadolinium isotopes and bromine isotopes. The nuclei of these isotopes emit very energetic gammas when neutrons are captured. These attributes allow alloys to be engineered from combinations of these isotopes and computationally optimized to produce cascades of penetrating gamma radiation that is useful for isotope production, electrical energy production and other national security applications. The vanadium isotopes, vanadium-50 and vanadium-51, produce gammas in excess of eleven million electron volts (11 MeV). The nickel isotopes, nickel-59 and nickel-61 produce photons whose energy is in excess of ten million electron volts (10 MeV). The europium isotopes produce photons whose energy in excess of eight million electron volts (8 MeV). Erbium produces gammas in excess of seven million electron volts (7 MeV). The iron isotopes provide energetic photons as do certain isotopes of palladium-105 paladium-107, bromine-79 and gadolinium-155 and gadolinium-157. Each neutron captured by the above mentioned isotopes of vanadium, nickel, palladium, bromine gadolinium, bromine and/or iron causes highly energetic gammas to be emitted from the nuclei. These gammas are penetrating and useful and the composition of the alloys can be optimized using these materials. The alloys comprising the invention, the gamma emitting alloys, will also contain materials that slow high energy neutrons produced from fission For example, vanadium-50, vanadium-51, nickel-59, nickel-61, iron-57 and iron-54 can be placed under a beryllium and lead shell that reflects produced neutrons back below the reflecting shell but allowing the gamma stream freely through the beryllium shell for applications outside of the neutron generator. On the inside of the inventive neutron generator in the central region proximate to the electron beam target is placed a layer of palladium, titanium, or erbium infused with tritium and deuterium. This matrix will generate secondary neutrons and will moderate fission spectrum neutrons. Beryllium-9 dissociates into a neutron and two alpha particles when it is hit with an energetic neutron whose collision energy is more than 1.67 million electron volts or when (with less likelihood) the beryllium nuclei interact with a gamma photon having an energy of more than 1.67 million electron volts. Deuterium dissociates into a neutron and a proton when it is hit with an energetic neutron whose collision energy is more than 2.24 million electron volts. There will be an increase in the population of neutrons cause by the multiplication effects of the levels of energies of the gamma photons and the presence of fissile material in the target. This feedback will contribute to gamma production and may obviate the need for continual input of electrons from the beam to supply primary neutrons. Pulses may be more separated in time as the neutronic feed back effects increase the neutron production rate. The various examples disclosed in this patent application are generally called embodiments of the neutron generator. The gamma,n effects will produce additional neutrons from target materials that are available for capture by the gamma emitting isotopes in the target. These neutrons will come from the beryllium nuclei or the deuterium or tritium nuclei or both. The neutrons will be slowed to the, epithermal and thermal energies where capture by the gamma emitting isotope is most probable or where fission is most probable. The gamma emitter alloy contains vanadium-50, vanadium-51, nickel-59, nickel-61, iron-57 or iron-54, or bromine-79, and selected lanthanides such as europium and/or erbium that are deuterated or tritiated for secondary and/or tertiary neutron production. The present invention considers the neutronic properties of the materials as well as the metallurgical aspects of the target alloy to optimize the production of neutrons for various functions adjacent to the generator. Another potential use of the inventive neutron generator is for power production applications, i.e, for motive power from direct conversion of gamma photons to electrical power. The gamma photons stimulate the movement of electrons taking advantage of the photoelectric effects to convert the nuclear energy, the gamma radiation, directly to electrical energy for motive power or other purposes. The high energy gammas produce pairs of electrons and holes in selected materials. The distribution of the energies of the neutrons leaving the target is managed and controlled by the thickness of the neutrons' average traverse through the alloys comprising the target, the geometry of the shaping alloy and the neutron scattering and slowing down properties engineered into the shaping or tailoring alloy for energetic gamma production to make neutrons available outside the target. The target alloy will include two or more gamma emitters having markedly different neutron capture cross sections so that as the neutrons slow down they will have opportunity to interact by capture reactions in two or more gamma emitting isotopes. The lanthanides have the largest cross sections and will capture neutrons at lower energies very efficiently. The gammas produced will generate more neutrons from the neutron donor materials. The action of an electron beam may be optimized in the alloy to produce secondary neutrons by particle interactions and by the photo nuclear effects caused by high energy gamma radiation. Having fully described several embodiments of the present invention, many other equivalents and alternative embodiments will be apparent to those skilled in the art. These and other equivalents and alternatives are intended to be included within the scope of the present invention. |
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abstract | A micro-scale power source and method includes a semiconductor structure having an n-type semiconductor region, a p-type semiconductor region and a p-n junction. A radioisotope provides energy to the p-n junction resulting in electron-hole pairs being formed in the n-type semiconductor region and p-type semiconductor region, which causes electrical current to pass through p-n junction and produce electrical power. |
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claims | 1. A method of creating desired isotopes in a commercial nuclear reactor generating heat for use in power production, the method comprising:operating the nuclear reactor to generate heat for use in power production,wherein the reactor includes an irradiation target holder in a core of the nuclear reactor, and the irradiation target holder being inaccessible from outside the reactor during the operating, wherein,the irradiation target holder directly contacts and is moveable within moderator of the nuclear reactor,the irradiation target holder is directly exposed to neutron flux from a plurality of fuel assemblies surrounding the irradiation target holder in the core during the operating,wherein the irradiation target holder is physically separate from all of the plurality of fuel assemblies,the irradiation target holder impermeably contains an irradiation target having a thermal neutron absorption cross section exceeding 1 barn and an atomic number less than 90, andthe operating irradiates the irradiation target holder with the neutron flux to produce a desired daughter product from the irradiation target. 2. The method of claim 1, further comprising:removing a startup source holder from the core; andinstalling the irradiation target holder in the core where the startup source holder was removed, wherein the removing and installing are performed during a non-operational period. 3. The method of claim 2, further comprising:retrieving the irradiation target holder from the core, wherein the retrieving is performed during a non-operational period. 4. The method of claim 3, wherein the retrieving includes moving at least one of the plurality of fuel assemblies directly adjacent to the irradiation target holder so as to expose and access the irradiation target holder. 5. The method of claim 2, wherein the removing withdraws at least a portion of the startup source holder from a penetration in a core plate supporting the plurality of fuel assemblies. 6. The method of claim 5,wherein the installing includes inserting at least a portion of the irradiation target holder into the penetration in the core plate previously occupied by the startup source holder and seating a fin of the irradiation target holder into an adjacent fuel casting on the core plate. 7. The method of claim 1, wherein the irradiation target is at least 0.1 kilograms of cobalt-59. 8. The method of claim 1, wherein the operating is performed for a plurality of months, and wherein the irradiation target holder is sealed inside the reactor during the operating, and wherein the irradiation target does not produce neutrons during the operating. 9. A method of creating desired isotopes in a commercial nuclear reactor generating heat for use in power production, the method comprising:removing a startup source holder from a startup holder position in a core of the nuclear reactor;installing an irradiation target holder in the startup holder position by inserting at least a portion of the irradiation target holder into a penetration in a core plate at a bottom of the core previously occupied by the startup source holder and seating a fin of the irradiation target holder into an adjacent fuel casting on the core plate;operating the nuclear reactor to generate heat for use in power production,wherein the reactor includes the irradiation target holder in the core of the nuclear reactor in the startup holder position directly exposed to neutron flux from a plurality of nuclear fuel assemblies surrounding the irradiation target holder and moderator in the core, and the irradiation target holder being inaccessible from outside the reactor during the operating, wherein,the irradiation target holder is physically separate from all the plurality of fuel assemblies and impermeably contains an irradiation target having a thermal neutron absorption cross section exceeding 1 barn and an atomic number less than 90, andthe operating irradiates the irradiation target holder with neutron flux to produce a desired daughter product from the irradiation target. 10. The method of claim 9, wherein the irradiation target is at least 0.1 kilograms of cobalt-59. 11. The method of claim 9, wherein the operating is performed for a plurality of months, and wherein the irradiation target holder is sealed inside the reactor during the operating, and wherein the irradiation target does not produce neutrons during the operating. |
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description | Referring to FIG. 1, a container suitable for storing spent fuel is designated generally by the reference numeral 10. The container comprises a canister 12 which is loaded with spent fuel rods 13 and is then is sealed with a welded lid. Once the spent fuel 13 is sealed within the canister 12 the canister 12 is vacuum dried then back filled with an inert gas, such as helium, which surrounds the spent fuel rods 13. Thermal conduction from the fuel rods 13 within the canister 12 is enhanced through the use of the helium atmosphere at a pressure slightly above atmospheric. Once loaded with spent fuel the canister 12 is positioned within a concrete cask 14 such that the outer surface 15 of the canister 12 and the inner surface 16 of the cask 14 are spaced apart from one another. This allows air flow from an air inlet 17 to an air outlet 18 formed in the outer wall 9 of the cask 14. It is necessary to have air flow passing over the canister 12 to maintain fuel temperature below regulatory limits. It is envisaged that the spent fuel rods 13 may be stored within container 10 for many decades. This means that it may be prudent to be able to provide for monitoring the contents of the canister regularly and reliably over these time scales to assist in demonstrating and confirming safe confined storage conditions to government regulatory officials. By means of the present invention it is possible to detect the leakage of oxygen from the surrounding air into the helium atmosphere with a sealed canister in a non-intrusive manner. By means of the present invention, the atmosphere of the canister is probed with ultrasonic signals. An ultrasonic signal transmitted into the canister will emerge from the canister, and by measuring changes in the ultrasound signature of the received signal produced by any oxygen influx, presence of oxygen may be detected. In particular, changes in sound velocity, attenuation, resonant frequencies and structures may indicate oxygen leakage into the canister. Additionally or alternatively variations in pressure within the canister may be monitored by detecting similar variations with pressure. Additionally or alternatively, as xenon and krypton gases may also be released during storage of spent fuel within the sealed canister in the event of failure of fuel rod cladding it, it is desirable to be able to monitor relatively small variations in the levels of such gases within the helium atmosphere. These affects can also be monitored by suitable consideration of their effect on the ultrasound investigation. For an ideal gas the sound velocity is given by: v = ( γ xe2x80x83 r xe2x80x83 T ρ ) 1 / 2 ( 1 ) wherexcex3=ratio of specific heats; r=gas constant; T=temperature; xcfx81=molecular weight. For a binary mixture xcex3, m are proportionally modified. As can be seen from equation (1) a variation in xcfx81 results from a variation in the relative He, O2 composition. Thus at 30xc2x0 C. a complete change of atmosphere from He (xcfx81=4, v=1024.7 msxe2x88x921), to oxygen (xcfx81=16, v=332 msxe2x88x921) leads to v0/vHe=xc2xc (or xcex4v≈660 msxe2x88x921. Calculations indicate that for a 10:90, O2:He mixture the sound velocity would be 764.4 msxe2x88x921 i.e., a change of 260.3 msxe2x88x921 (≈25%) from pure He. This variation is easily detectable experimentally and is particularly suited to mono-atomic gases, as is the case in the surrounding gas for spent fuel rod storage. Equation (1) also indicates that the velocity scales with T as it does with p so that a temperature change from 30 to 300xc2x0 C. would approximately lead to a velocity increase of x(3xe2x86x924). As a consequence of this variation it is of the utmost importance in many applications to provide for an accurate compensation for any temperature variation between measurements. This can be achieved by direct measurement of temperature conditions, with appropriate compensation for changes. However, it is a particularly significant advantage of the present invention that investigation at a number of frequencies can also determine temperature and thus account for it. Pressure variations are, however, sufficiently small to have no meaningful effect. As well as allowing consideration of O2 levels in the He atmosphere, any Xe, Kr released from the fuel would also affect xcfx81 (for Xe, xcfx81=131; Kr, xcfx81=84). Proportionately smaller amounts of Xe, Kr could produce significant sound velocity changes of the cask atmosphere due to further variation in xcfx81 and hence v. The sonic velocity will vary with both frequency and gas pressure. The variation is due to visco thermal, and in the case of diatomic gases, vibrational and rotational relaxation effects. As well as variations in the speed of the ultrasound travel, variations in the attenuation of the sound wave can be expected. The attenuation, xcex1, of a soundwave in a gas is usually quoted in terms of the parameter: ( α xe2x80x83 p f 2 ) where (xcex1=absorption coefficient; p=gas pressure;ƒ=frequency). The total absorption in a binary gas mixture in which one component is polyatomic is the sum of three terms: α xe2x80x83 p f 2 = xe2x80x83 F 1 , ( viscosity , thermal xe2x80x83 conduction xe2x80x83 ) + F 2 , ( diffusion xe2x80x83 ) + F 3 xe2x80x83 ( vibration / rotation xe2x80x83 energy xe2x80x83 relaxation xe2x80x83 ) . As a variation in the components present changes xcex1 the attenuation effects can also, therefore, be used for also detecting differences in concentration of two binary components and for distinguishing between different contaminants and temperature effects. Thus, for example (xcex1p/ƒ) for He and a 10:90 O2 He mixture are 0.525 and 1.546 respectively so that a 10% oxygen contamination would produce a factor of 3xc3x97 change. The above mentioned theoretical techniques can be deployed according to the present invention in a variety of different manners. In the following examples particular emphasis is placed on the monitoring of canisters for spent nuclear fuel. The embodiment illustrated in FIG. 2 shows the top portion of a canister of the general type designated 12 in FIG. 1. The canister 200 comprises a cylindrical side wall 202 and lid structure 204. The lid structure 204 is formed of an inner shield lid 206, which rests on lip 208, and an outer structural lid 210, which rests on lip 212. Both the shield lid 206 and structural lid 210 are welded in position with gas tight welds. The spent fuel rods are contained in the volume 214 below the shield lid 206. Mounted on the structural lid 210 is the monitor housing 216. The housing 216 provides a structural wall thickness 218 around the monitoring location 220. The structural wall thicknesses required to met regulatory standards vary for materials (for instance 25 mm thickness for carbon steel, 19 mm thickness for stainless steel). The monitoring location 220 consists of a cylindrical bore 222 leading from the cavity volume 214 to the monitoring location 220 and beyond to a xe2x80x9ctop hatxe2x80x9d configuration 224. The bore 222 is fully enclosed by the housing 216 to maintain the isolation of the cavity volume 214 and its helium atmosphere from the surrounding cooling air volume 226. The bore 222 is dog leg for shielding purposes. On either side of the monitoring location are two bores 228 in the housing 216, the bores receiving the transmission transducer 230 and receiver 232. Ultrasound is passed through the monitoring location 220 and the appropriate characteristics of its passage are measured to give the desired information. Although physically remote from the cavity volume 214 measurements at the monitoring location 220 are accurate representations of the cavity volume due to the extreme mobility of helium. Additionally the time period between measurements is likely to be days or more with very gradual or no change expected between tests, as a consequence this gas volume is fully representative. As illustrated in more detail in FIG. 3, the bore 222 consists of a main bore 234 and subsidiary bore 236 connected by a cross-bore 238. The housing 216 is mounted on the structural lid 210 by plate 240 which is welded thereto by welds 242 and 244. To ensure good ultrasound contact between the transducers 230, 232, gel is provided on the end faces of the bores 228. As alternatives to flat ends for the bores, concave or convex faces can be used to focus the ultrasound. The top hat shape to the upper section 246 of the bore 222 is so shaped for the purposes of damping noise signals spreading from the source to receiver transducer. The transducers 230, 232 face each other across a gap of 5 to 6 cm in the case of a 40 kHz ultrasound system. As an alternative to direct contact between the end of the bore and the transducer, the transducers may be provided with plates connected to the end surfaces of the transducers by spigots. Whilst FIGS. 2 and 3 imply the use of a unitary element to form the housing 216 acoustic filtering advantages can be obtained by forming the housing of different materials. The different materials may filter the noise signal and/or give enhancing directional effects. Acoustic filtering of the signals arising in the system, through appropriate structural configurations, is important in ensuring that the quicker signal transmission of the ultrasound through the housing does not give a noise signal which swamps the slower transmission of the ultrasound through the gas being monitored. The frequency of the ultrasound, the gap between the transducers, the relative thicknesses of the intervening walls, side walls and surrounding walls all, individually and together, effect the system and can be used to effect its operation accordingly. The transducers 230, 232 are only introduced once the fuel has been loaded, as part of the loading procedure will involve the complete emersion of the canister 200 including the housing 216 in the cooling pond where the fuel is stored. The transducers 230, 232 and accompanying electronics to which they are attached (not shown) are removed from the housing 216 between tests to reduce the potential for radiation damage of the transducers and their surrounding electronics and also to reduce the number of measuring equipment sets that are needed. As tests on the gas content may be days, months or even years apart, it is wasteful to leave that part of the equipment in-situ during that time. In general, the measurement system is checked against a known standard or other calibration technique, before and/or after being used, to ensure correct operation. True verification of the systems correct operation can therefore be provided, away from the canister if desired. To give accurate measurements the temperature of the monitoring location is measured. The temperature monitoring can be effected by a thermal couple attached to the housing at a consistent position between tests. A pair of thermocouple, one at substantially the same location as the transmitting transducer, one at substantially the same position as the receiver are preferred in this regard. There is no need for the temperature monitoring apparatus to intrude into the internal cavity (thereby avoiding leakage site generation) provided a consistent correction is applied. The output from the thermocouples are fed to the processing electronics to provide a correction signal. This signal can be used to correct the gas monitoring result to ensure that variations in temperature, for instance cooling of the canister over the years, does not give a false reading of gas change. Measurement of pressure within the cavity may also be desirable to remove the effect of any pressure variation from the signal analysis in a similar manner to that discussed above for temperature. In FIG. 4 an alternative positioning of the housing 216 is provided on the top wall 400 of the cylindrical wall 402 of the canister 200. This provides the necessary clearance for the introduction of the shield lid 204 and structural lid 210 following introduction of the spent fuel. The connection between the monitoring location 404 and the cavity volume 406, in this case, is provided by a bore 408 in the cylindrical side wall 402. The monitoring operates in a similar manner to that outlined above. In FIG. 5 the housing 216 is provided on the end of a bore carrying element 500 fixed to the side wall 502 of the canister. The bore 504 in this element 500 connects the measuring location 506 to the cavity volume 508. In the alternative form of mounting for the housing 216 of FIG. 2, illustrated in FIG. 6, the housing base 600 penetrates the structural lid 210 and rests on the shield lid 204. In this way only the, relatively narrow, bore carrying element 602 needs to penetrate the shield lid 204, thereby reducing the variation between the existing canister and a canister 200 embodying the present invention. In the still further alternative form of mounting for the housing 216 shown in FIG. 7, the housing 216 rests on the top surface 700 of the structural lid 210. In this way the structural lid 210 and the shield lid 204 are both only penetrated by the relatively narrow, bore carrying element 702. In certain instances the housing must have quite deep bores for the transducers to give sufficient signal introduction and sufficient signal collection capability for the best results to be achieved. Transducers of 6 to 8 inches in length and 3 inches in diameter are suitable for many applications. In general the longer the transducer the better the filtering that is achieved. The FIG. 4 and FIG. 5 type embodiment positioning of the housing can be a problem in this regard. FIG. 8 illustrates an embodiment of the invention which provides the necessary clearance for the lids 800, but provides the necessary bore length 802 by extending the housing 804 around and within the profile of the cylindrical wall 806. This form of housing 804 also avoids intrusion of the housing 806 outside the cylindrical profile, an important consideration given the very limited clearances which exist between the outside 810 of the cylindrical wall 806 and other parts of the apparatus during transfer of the canister from the cooling pond, where it receives the spent fuel, and the concrete cask. The FIG. 8 and other embodiments of the invention illustrate a transmission system for determining the ultrasonic effects. This and the other embodiments of the invention can, however, use reflective measurements. In such cases a substantially coincident transmission and reception location may be provided or the transmission and reception locations may be provided close to one another, but separated by a small angle. The opposing side of the bore containing the gas may be shaped to promote ultrasound reflection. To illustrate the techniques effectiveness reference is made to FIG. 9 which displays the time difference between signal emission and reception against different gas compositions for air to helium mixtures. In FIG. 10 a typical input signal (solid line 1000) and a typical detected signal (solid line 1002) are illustrated. The detected form includes both that part of the signal which crosses the gas gap to the detector and also a significant noise signal which travels around through the housing itself to reach the detector. To achieve the necessary accuracy in the results using the techniques of the present invention it is desirable to apply certain signal processing techniques. Preferred embodiments of the invention use Fast Fourier Transform method or the new technique of chromatic filtering to extract the desired information from the detected signal. The technique of chromatic processing is illustrated in FIG. 11a to 11c. Chromatic filtering of a signal (FIG. 11(a)) involves the use of n nonorthogonal Gaussian processors (FIG. 11(b)) which cover the range of frequencies covered by the signal. In one embodiment n=3 the outputs of the Gaussian processors are manipulated algorithmically to provide at each instant in time a signal detection in terms of three parameters namely the nominal energy content of the signal, the dominant frequency and the effective bandwidth. The signal is effectively represented by a single point in a three dimensional chromatic space defined in terms of these parameters (FIG. 11(c)). In this embodiment the conditions within the fluid containing canister are defined by the position of the signal defining point in chromatic space. Deviation of this point from its nominal equilibrium position is indicative of changed conditions in the canister. Experience with other measurements indicate that: The type of fault producing a change is characterised by the direction of the deviation from equilibrium. The extent of fault development is characterised by the magnitude of the change. Fault types and their characteristics are determined empirically from a prior calibration. From the above mentioned three parameters the time of flight of the ultrasound through the gas gap can be determined in the desired manner. The process also reveals significant other information on differential attenuation and propagation which can be used. It is likely that some resonant frequencies of the gas containment facility will depend upon the mass density of the gas within the structure. There is, therefore, the possibility of exploring whether such an approach could yield further information about the composition of the gas atmosphere. At one extreme such an approach might give a better xe2x80x9cintegrated atmospherexe2x80x9d indication since major parts of the casket volume would have an effect (rather than simply a xe2x80x9cline of sightxe2x80x9d, local indication). At the other extreme, a xe2x80x9cline of sightxe2x80x9d approach may well, in any case, excite resonances which will need to be taken into account in the analysis of test results. Sound velocity and attenuation co-efficient may be evaluated in detail for the gaseous components He, O2, N2, Xe and Kr separately in various combinations for a range of acoustical frequencies. The purpose of these calculations is to determine the extent to which the different atmospheric combinations within the fuel storage canister might be distinguished. Differences in acoustical velocities will indicate the presence of different species. Differences in attenuation coefficient will indicate temperature effects, whilst the frequency dependence of the velocity and attenuation coefficient may enable different contaminants to be distinguished. Calculations used to determine the composition of a gas content within a canister will take into account the structural considerations of the canister. Some of the resonances will depend on the mass density of the gaseous atmosphere. When putting the invention into practice it is necessary to define a range of sonic frequencies to be used in order to maximise trends and variations between different contaminants. For example, it may be possible to discriminate between oxygen and Xe/Kr on the basis of the rotational energy and relaxation of the oxygen molecule if sufficiently high frequencies are employed. In addition, for xe2x80x9cline of sightxe2x80x9d measurements sonic attenuation will have to be minimised for appropriate choice of frequency when taking into account the structure. The acoustic transducer could be either electromagnetic, a capacitance, or any other type of transducer. Depending on the choice of source and detector, it may be advantageous to use optical fibres in order to detect the received signal. Although the present invention has been described primarily with reference to use in connection with monitoring of spent nuclear fuel contained within fuel canisters, the invention would also be applicable in areas where materials which are harmful to human beings are being handled or transported, for example, toxins, biological materials and medical materials. |
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053612833 | summary | BACKGROUND OF THE INVENTION 1. Field of the Invention The invention is generally related to nuclear fuel assemblies and more particularly to a reusable locking arrangement for guide tubes and upper end fittings. 2. General Background In a nuclear reactor core, each fuel assembly is fitted with a number of guide tubes that are used to receive control rods. In the nuclear industry, the tubes that are used to receive control rods are referred to as guide tubes or thimble tubes and the upper internal structure that these tubes are attached to are referred to as an upper end fitting or a top nozzle, depending on the manufacturer. Therefore, it should be understood that references herein to a guide tube and upper end fitting should be considered as also referring to a thimble tube and top nozzle. The guide tubes have a relative thin wall thickness and thus require a sleeve at the upper end to provide the necessary support for attachment points and shoulder stops. During assembly, the guide tubes are inserted into the spacer grids. The upper end fitting is then aligned with, received on, and attached to the upper end sleeves of the guide tubes. Typically, upper end fittings and sleeves are attached to one another by the use of threaded joints and locking cups. When it becomes necessary to remove an irradiated fuel assembly upper end fitting or nozzle at the reactor site, the work must be done with remotely controlled tooling under water. This results in the handling of a number of parts and provides the potential for cross threading the fasteners during installation. The remote handling of a number of parts under water increases the potential for loose parts in the system that can damage the reactor and increases working time. Patents directed to nuclear fuel assembly end fitting retainers that applicant is aware of include the following. U.S. Pat. No. 3,769,158 discloses the use of an end fitting over fuel rods where a reduced neck extending through the opening in the end fitting has resilient split rings in grooves and engage the end fitting. U.S. Pat. No. 3,828,868 discloses guide tubes that are threadably attached to the end fitting. U.S. Pat. No. 4,699,761 discloses the use of a threaded sleeve on the upper end of the guide tube. SUMMARY OF THE INVENTION The invention addresses the above need. What is provided is an integral, reusable inexpensive locking arrangement between the guide tube assembly and upper end fitting that eliminates all loose fastener components at the reactor site. A retainer sleeve is fabricated to cooperate with the upper end sleeve of the guide tube assembly. Slots adjacent to the upper end of the sleeve receive rigid tabs on the upper end sleeve to hold the retainer sleeve and upper end sleeve together. The retainer sleeve is formed from a cylindrical tube that has a plurality of flexible tabs spaced around the circumference of the tube substantially at the mid section of the tube. Optional lower tabs serve to center the guide tube assembly in the upper end fitting and provide a more rigid connection. The mid section tabs are received against the shoulders of slots provided along the walls of the hole in the upper end fitting and serve to retain the guide tube assembly and upper end fitting in the installed position. The retainer sleeve is rotated to force the tabs inward to allow for removal of the upper end fitting from the guide tube assembly. |
abstract | Methods for distributing a random variable by spatial interpolation with statistical corrections. The method includes assigning a numerical value of the random variable at each vertex of an array of equilateral triangles formed in a planar coordinate frame and defining a plurality of test points at respective spatial locations in the planar coordinate frame that are bounded by the array of equilateral triangles. A numerical value of the random variable is distributed at each of the test points by spatial interpolation from one or more of the numerical values of the random variable assigned at each vertex of the array of equilateral triangles. The method further includes adjusting the numerical value of the random variable distributed at each of the test points with a respective correction factor. |
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description | This application is a divisional application claiming priority under 35 U.S.C. § 121 to U.S. patent application Ser. No. 15/681,484, entitled INSPECTION TOOL, filed Aug. 21, 2017, which issued as U.S. Pat. No. 10,672,526 on Jun. 2, 2020, the entire disclosure of which is hereby incorporated by reference herein. The disclosed and claimed concept relates generally to a tool that is usable in an irradiated environment and, more particularly, to a tool that is usable to be received into an interior region of a core shroud of a boiling water reactor and that is structured to carry a device thereon into the interior region. Numerous types of nuclear reactors are known to exist in the relevant art. Such known nuclear reactors can be said to include pressurized water reactors (PWRs) and boiling water reactors (BWRs), each of which typically is connected with an electrical generator as part of a nuclear power plant. Various components and structures in a nuclear reactor are examined periodically to assess the structural integrity of such components and structures and to indicate the need for repair. Ultrasonic inspection is a known technique for detecting cracks in nuclear reactor components and structures. However, the inspection areas in a nuclear reactor may have limited access and therefore may be difficult to assess using an inspection tool. For example, the reactor core shrouds of BWRs are periodically assessed for cracking inasmuch as the presence of cracking can diminish the structural integrity of the core shroud and can disrupt plant operations. However, the core shroud welds are difficult to access. More specifically, access to such a core shroud at the outer cylindrical surface is typically limited to the annular space between the outer surface of the core shroud and the inner surface of a reactor pressure vessel in areas between adjacent jet pumps. Access for purposes of ultrasonic scanning is further restricted within the narrow space between the inner surface of the reactor pressure vessel and the jet pumps and other attachments such as the riser brace or restrainer brackets that protrude radially outwardly from the cylindrical outer surface of the core shroud. Furthermore, and depending upon the specific plant installation, some core shrouds and welded attachments may be entirely inaccessible at the exterior surface of the core shroud. It is further noted that the inspection areas in a nuclear reactor can be highly radioactive and can pose safety risks for personnel working in these areas. The inspection and repairing of nuclear reactors, such as BWRs, typically consists of operating manually-controlled poles and ropes to manipulate and/or position the inspection devices. During a reactor shutdown, the servicing of some components requires the installation of inspection manipulation devices 30 to 100 feet deep within the reactor coolant. Relatively long durations are required to install or remove manipulators at such depths, which can impact the duration of the plant shutdown. In addition, different inspection devices can require several different manipulators or reconfigurations of manipulators in order to perform an inspection, which requires additional manipulator installations and removals, and thus added cost. The long durations impact not only plant shutdown durations but also have the effect of increasing the radiation and contamination exposure to personnel performing the inspection operations. Plant utilities thus have a desire to reduce the number of manipulator installations and removals in order to reduce the radiological exposure as well as the cost and impact of plant outages. Furthermore, plant utilities have a desire to reduce cost and to operate as productively as possible. Improvements thus would be desirable. An improved tool is configured to be received into an interior region of a core shroud of a BWR. The tool is structured to carry thereon a device into the interior region. The device can be a test instrument that is capable of performing an ultrasonic scanning operation on the core shroud, or it can be another device. The tool includes an elongated frame, an elevator apparatus situated on the frame, and a manipulator apparatus situated on the elevator apparatus. The tool further includes a reciprocation apparatus that is situated on the manipulator apparatus and that has a mount that is structured to carry the device thereon. The reciprocation apparatus includes an elongated rack of an arcuate profile that matches the profile of the inner surface of the core shroud. Movement of the elongated rack with respect to the manipulator apparatus causes a mount that is situated on the rack and the device that is carried on the mount to move along an arcuate path to inspect the core shroud along a circumferential direction. The elevator apparatus is operable to move the reciprocation apparatus along the longitudinal extent of the frame in order to move the mount and the device carried thereon along an axial direction on the core shroud. The manipulator apparatus is operable to move the reciprocation apparatus between a retracted position received in an elongated receptacle formed on the frame and a deployed position wherein the reciprocation apparatus is removed from the receptacle and the device is therefore deployed for inspection purposes. In the retracted position, the tool is receivable through an opening in a top guide of the BWR and into a fuel cell from which the nuclear fuel has been removed. The tool further includes a foot apparatus that is situated at an end of the frame and that is receivable on a core plate to enable the frame to be pivoted about an axis of elongation of the frame with respect to the core plate. Accordingly, an aspect of the disclosed and claimed concept is to provide an improved tool that is structured to be received in an interior region of a core shroud of a BWR and that is structured to carry an inspection device or other device thereon into the interior region. Another aspect of the disclosed and claimed concept is to provide an improved tool that can be received through an opening in the top guide and into a fuel cell of the BWR from which the nuclear fuel has been removed. Another aspect of the disclosed and claimed concept is to provide an improved tool having a reciprocation apparatus that is operable to move a device that is situated on a mount along an arcuate path along an interior surface of the core shroud of the BWR. Another aspect of the disclosed and claimed concept is to provide a reciprocation apparatus that is receivable on such a tool and that is adapted to enable movement of a device that is situated on a mount of a reciprocation apparatus along an arcuate path. Another aspect of the disclosed and claimed concept is to provide an improved tool having a manipulator apparatus that is mountable on an elevator apparatus in either of a pair of configurations, in one configuration the manipulator apparatus extending from the elevator apparatus in a direction generally toward the foot apparatus, and in a second configuration the manipulator apparatus extending from the elevator apparatus in a direction generally away from the foot apparatus. These and other aspects of the disclosed and claimed concept are provided by an improved tool that is structured to be received into an interior region of a core shroud of a boiling water reactor and that is structured to carry a device thereon into the interior region. The tool can be generally described as including a frame, the frame being elongated along an axis of elongation and having a receptacle formed therein that is elongated along the axis of elongation, an elevator apparatus situated on the frame, a manipulator apparatus situated on the elevator apparatus, at least a portion of the manipulator apparatus being situated in the receptacle, a reciprocation apparatus that can be generally described as including a support that is elongated and that is situated on the manipulator apparatus, the reciprocation apparatus further can be generally described as including a mount that is situated on the support and that is structured to carry the device, the elevator apparatus being operable to move the manipulator apparatus between a first position and a second position along the longitudinal extent of the frame, the manipulator apparatus being operable to move the reciprocation apparatus between a first position wherein the support is disposed at least in part in the receptacle and a second position wherein the support and the mount are removed from the receptacle, and a foot apparatus situated on the frame and that can be generally described as including a number of feet and a pivot mechanism, the number of feet being situated at an end of the frame and being structured to be received on at least one of a fuel support, a control rod guide tube, and a core plate of the boiling water reactor, the pivot mechanism being structured to pivot the frame about the axis of elongation with respect to the number of feet when the number of feet are received on the at least one of the fuel support, the control rod guide tube, and the core plate. Other aspects of the disclosed and claimed concept are provided by an improved reciprocation apparatus that is structured to be mounted to a tool which is receivable into an interior region of a core shroud of a boiling water reactor, the reciprocation apparatus further being structured to carry a device thereon into the interior region. The reciprocation apparatus can be generally stated as including a platform that is structured to be situated on the tool and that has a first side and a second side opposite one another, a support that is elongated and that is situated on the platform, the support having a first end and a second end opposite one another, the support being movable along its direction of elongation with respect to the platform in a first direction wherein the first end moves relatively farther away from the first side, the support further being movable in a second direction opposite the first direction wherein the second end moves relatively farther away from the second side, a belt that is elongated and flexible, the belt being affixed at one or more locations along its length to the platform to form a closed loop that extends about at least a portion of the support and that permits relative movement between the belt and the at least portion of the support when the support moves in the first and second directions, a mount that is situated on the belt and that is structured to carry the device, a drive mechanism operationally extending between the support and one of the platform and the belt, the drive mechanism being operable to move the reciprocation apparatus between a first state of the reciprocation apparatus and a second state of the reciprocation apparatus, in the first state, a relatively greater portion of the support extends from the first side than extends from the second side, and the mount is situated relatively closer to the first end than the second end, and in the second state, a relatively greater portion of the support extends from the second side than extends from the first side, and the mount is situated relatively closer to the second end than the first end. Similar numerals refer to similar parts throughout the specification. An improved tool 4 in accordance with an aspect of the disclosed and claimed concept is depicted generally in FIGS. 1-12 and is depicted in part in FIGS. 13-22. The tool 4 is configured to carry a device 6 (FIG. 7) thereon into an interior region 8 of a nuclear reactor such as a boiling water reactor (BWR) 10, as is depicted in FIG. 2. The device 6 may be, for example, an ultrasonic testing device or other such testing or evaluation device, or it alternatively might be some type of a device that physically interacts with an object at the interior region 8, such as a device that grasps or moves an object within the interior region 8, by way of example and without limitation. As can be seen in FIG. 2, the BWR 10 includes an annular shroud 12 that is situated within the interior region of a reactor pressure vessel 15. The shroud 12 has an interior surface 14 that faces away from the reactor pressure vessel 13 and that is the surface of the shroud 12 at which an inspection of the shroud 12 can be conducted with the use of the tool 4, such as if the device 6 is an ultrasonic sensor. As can be understood from FIG. 4, the shroud 12 has a number of welds formed therein that include a vertical weld 16 and a horizontal weld 18. As employed herein, the expression “a number of” and variations thereof shall refer broadly to any non-zero quantity, including a quantity of one. The vertical weld 16 can be said to extend along an axial direction 17 of the shroud 12, and the horizontal weld 18 can be said to lie along a circumferential direction 19 which can also be referred to herein as an azimuthal direction. As can be understood from FIG. 2, the BWR 10 further includes a core plate 20 upon which the tool 4 can be situated and a top guide 26 that is spaced vertically above the core plate 20. The BWR 10 has a plurality of fuel cells 22 formed therein that each include an opening formed in the top guide 26, and each of which is structured to have nuclear fuel situated therein when the BWR 10 is in operation. Furthermore, it is noted that the BWR 10 is depicted herein, i.e., in FIGS. 2 and 4, as having all of the fuel removed therefrom for purposes of simplicity of depiction. It is also expressly noted that the tool 4 is designed to be used in conjunction with the BWR 10 without the need to remove all of the fuel and other materials from the fuel cells 22. That is, the tool 4 is advantageously configured to be received in a fuel cell 22 after the fuel has been removed therefrom, but with a minimal need to remove fuel from the fuel cells 22 adjacent thereto. For example, FIG. 2 depicts the tool 4 being received in a fuel cell 22A of the plurality of fuel cells 22. FIG. 2 also depicts the tool 4 being pivoted (in a fashion that will be described in greater detail below) such that a portion thereof protrudes into an adjacent fuel cell 22B and into an adjacent region 22C that does not actually receive fuel therein. As such, it can be understood that the other fuel cells 22 that are depicted in FIG. 2 as being without fuel and the like need not have their fuel and the like removed therefrom in order to receive the tool 4 in the fuel cell 22A and have it perform an inspection on the interior surface 14 in the vicinity of the fuel cells 22A and 22B, and in such circumstances it is necessary only to remove the fuel from the fuel cells 22A and 22B. This advantageously reduces the time and effort required to perform an inspection on the interior surface 14 of the shroud 12 by limiting the amount of fuel that must be removed from the fuel cells 22 in order to perform the inspection operation on the interior surface 14 of the shroud 12. As can further be seen in FIG. 2, the core plate 20 has a plurality of sockets formed therein that are indicated generally at the numerals 24A, 24B, 24C, and 24D, and which can be collectively or individually referred to herein with the numeral 24. Each fuel cell 22 has a set of sockets 24A, 24B, 24C, and 24D that are configured to receive therein a cooperating structure of the tool 4 that will be described in greater detail below. When the BWR 10 is in operation, the receptacles 24 accept the reactor fuel support casting and various fuel lattice structures. It thus can be understood that when the BWR 10 is to be inspected or to have an operation performed thereon with the tool 4, one of the fuel cells 22 that is situated nearby the interior surface 8 will need its fuel removed therefrom in order to receive the tool 4 therein. The fuel that is in one or two additional fuel cells 22 that are adjacent the fuel cell 22 that is to receive the tool 4 may need to be removed in order to permit maneuvering of the tool 4 as will be described below. As can be understood from FIG. 1, the tool 4 is connected with a computer system 28 via an umbilical 30. The computer system 28 includes an input apparatus that can include various input devices such as a keyboard, joystick, and other control input devices. The computer system 28 further includes an output apparatus that can include various output devices such as a visual display, a printer, an audible output system such as a loudspeaker, and the like without limitation. The computer system 28 additionally includes a processor apparatus that is in communication with the input apparatus and the output apparatus and which has various routines executable thereon to cause the tool 4 to perform various operations. It is to be understood that the tool 4 and its various subassemblies are robotic in nature, meaning that they include actuators that are operated electronically via electric motors or via pneumatically-operated motors or cylinders, or the like. As such, it is understood that the umbilical 30 can include not only electronic communication channels in the form of wires and the like, but can also include air or other fluid channels that convey fluid to the tool 4 in order to actuate certain subassemblies thereof. In this regard, it is understood that the computer system 28 may communicate wirelessly with the tool 4 without departing from the spirit of the instant disclosure. The tool 4 can be said to include an elongated frame 32 that is elongated along an axis of elongation 34. The tool 4 further includes a foot apparatus 36 that is situated at an end of the frame 32 and which includes a foot assembly 37 having set of four feet 38 that are configured to be received in the sockets 28A, 28B, 28C, and 28D of a fuel cell 22 in which the tool 4 is received. In this regard, it is understood that the feet 38 can be received on any of a variety of parts of the BWR 10, such as any one or more of a fuel support, a control rod guide tube, or the core plate 20 of the BWR 10, by way of example. The fuel support is a piece of reactor hardware that sits on the top of a control rod guide tube. The top of the control rod guide tube protrudes slightly through the top of the core plate 20 and supports the weight of the fuel support. The feet 38 can be reconfigured as needed to permit installation of the tool 4 into a guide tube or on the core plate 20, by way of example, if the customer has the control rod guide tube and/or the fuel support removed. The foot apparatus 36 further includes a pivot mechanism 40 that causes the frame 32 to pivot with respect to the feet 38 about an axis of rotation which, in the depicted exemplary embodiment, is coincident with the axis of elongation 34. In this regard, the pivot mechanism 40 includes a motor 42 that is connected via gears between the frame 32 and the feet 38, and which can be energized or otherwise actuated to operate the pivot mechanism 40 to pivot the frame 32 about its axis of elongation 34 with respect to the feet 38. More specifically, and as is shown in FIG. 11A, the motor 42 includes a shaft 39 and further includes a pinion gear 41 situated on the shaft 39. The foot assembly 37 further includes situated thereon a reaction gear 43 that is engaged by the pinion gear 41 to pivot the frame 32 about its axis of elongation 34 with respect to the feet 38 when the motor 42 is energized or is otherwise actuated. A bearing 45 is interposed between the end of the frame 32 and the foot assembly 37 in order to reduce friction therebetween when the frame 32 is being pivoted with respect to the feet 38. In the depicted exemplary embodiment, the bearing 45 is a deep groove ball bearing, but it is understood that other types of bearings can be employed without departing from the spirit of the instant disclosure. As can be seen in FIG. 1, for example, the frame 32 has an elongated receptacle 44 formed into what can be characterized as a frontal face 46 of the frame 32. The receptacle 44 is elongated along the axis of elongation 34. The frame 32 can be said to additionally include a rear face 48 (FIG. 2) opposite the frontal face 46, and to further include a pair of chamfers 50A and 50B that are formed in the frame 32 and that extend between the rear face 48 and the pair of lateral surfaces 51A and 51B, respectively. As can be understood from FIG. 2, the chamfers 50A and 50B, which may be collectively or individually referred to herein with the numeral 50, provide clearance between the frame 32 and the fuel cell 22 that is situated adjacent the fuel cell 22 where the tool 4 is situated. Such clearance enables the pivot mechanism 40 to pivot the frame 32 with respect to the core plate 20 without a meaningful risk of striking or otherwise engaging the fuel that is situated in such adjacent fuel cell 22. It is noted that the chamfers 50 can be of different configurations and profiles, such as rounded radii or otherwise arcuate, or can be of other angles with respect to the rear face 48 and the lateral surfaces 51A and 51B without departing from the spirit of the instant disclosure. As can be understood from FIGS. 1 and 2, by way of example, the frame 32 includes a head 47 at an end thereof opposite the foot apparatus 36. The head 47 is of a round shape within a plane oriented transverse to the axis of elongation 34. The head 47 has formed therein an access port 49 that can receive therein another device such as a camera 53. The camera 53 would typically be connected via a cable 55 with a video system, and the cable 55 may be a part of the umbilical 30. By providing the pivot mechanism 40 at the bottom end of the tool 4 rather than at the top end of the tool 4 the head 47, the head 47 has sufficient free space inside that it can advantageously have the access port 49 formed therein, which permits the camera 53 or other device to be received into the access port 49. The access port 49 provides access into the receptacle 44, which enables access between the receptacle 44 and, for instance, the region that is situated vertically above the tool 4. For instance, the camera 53 can be received through the access port 49 into the receptacle 44 in order to remotely observe the operations of the device 6 and the functioning of the tool 4. Further advantageously, by providing the pivot mechanism 40 to be situated between the foot assembly 37 and the frame 44 and to thus pivot the entire frame 44 with respect to the feet 38, the pivoting of the frame 44 about axis of elongation 34 can cause the umbilical 30 to move within the water that is situated in the BWR 10. That is, in certain situations such as the removal of fuel from a fuel cell 22, the narrow confines of the BWR may result in a physical conflict between the umbilical 30 and the fuel that is being removed, by way of example. The pivot mechanism 40 thus can be advantageously operated to pivot the frame 44 and thus to thereby reposition the umbilical 30 within the water of the BWR 10, thus resolving the conflict between the umbilical 30 and the fuel being removed and therefore advantageously avoiding physical contact between them. The tool 4 further includes an elevator apparatus 52 that is depicted in FIG. 11 as being situated on the frame 32 and including a drive motor 54 and a drive screw 56. The drive screw 56 is cooperable with a follower 58 (FIG. 16). The drive motor 54 is operatively connected with the drive screw 56, which is in the form of a jack screw or other type of threaded elongated device, and which is threadably connected with the follower 58. As can be seen in FIG. 16, the follower 58 is affixed to a manipulator apparatus 60. As can be understood from FIGS. 8, 10, and 11, when the drive motor 54 is energized, or is otherwise caused to operate, the drive screw 56 is caused to rotate within the receptacle 44 and to threadably engage the follower 58, which causes the follower 58 and the manipulator apparatus 60 to be translated along the axis of elongation 34 of the frame 32. For example, the position of the manipulator apparatus 60 in FIG. 1 with respect to the frame 32 is different than the position of the manipulator apparatus 60 in FIG. 3 with respect to the frame 32. Such a translation of the manipulator apparatus 60 along the axis of elongation 34 results from the drive motor 54 of the elevator apparatus 52 having been energized or otherwise caused to operate the drive screw 56 in order to threadably engage the follower 58 and to translate the manipulator apparatus 60 within the receptacle 44 along the axis of elongation 34. As can be understood from FIGS. 1 and 16, by way of example, the manipulator apparatus 60 can be said to include an extension apparatus 62 and a rotation apparatus 64 that are connected with one another. The extension apparatus 62 is situated on the elevator apparatus 52, and the rotation apparatus 64 is situated on the extension apparatus 62. The extension apparatus 62 can be said to include a four bar linkage 66 and a driver 68. As can best be seen in FIG. 16, the four bar linkage 66 can be said to include a stand 69 upon which the follower 58 is situated, a first link 70 and a second link 72 that are pivotably connected with the stand 69 and that each extend away therefrom, and a body 74 that is pivotably connected with the ends of the first and second links 70 and 72 opposite the stand 69. The stand 69, the first and second links 70 and 72, and the body 74 together function as a four bar linkage, which is the four bar linkage 66. It can be understood from FIGS. 16-18 that the driver 68 operatively extends between the stand 69 and the first link 70. The driver 68 can be any of a wide variety of devices such as pneumatic cylinders, stepper motors, and other such devices that are configured to have a variable length and to thereby operate the four bar linkage 66 between a retracted position, such as is depicted generally in FIGS. 9-12 and an extended position such as is depicted generally in FIGS. 1, 3, and 5, by way of example. As will be set forth in greater detail below, the four bar linkage 66 is situated in the retracted position of FIGS. 9-12, by way of example, when the tool 4 is being received in the fuel cell 22 and being removed therefrom, whereas the extension apparatus 62 is typically in an extended position, some examples of which are depicted in FIGS. 1, 3, and 5, when an inspection operation or other operation is being performed by the tool 4 situated in the fuel cell 22. As can be understood from FIGS. 13-15, by way of example, the rotation apparatus 64 is situated on the body 74. The rotation apparatus 64 can be said to include a pair of actuators that are indicated generally at the numerals 76A and 76B, and which can be collectively or individually referred to herein with the numeral 76. The rotation apparatus 64 further includes a crank 68 that is pivotably situated on the body 74 and a base 80 that is situated on the crank 78. The actuators 76A and 76B each include a cylinder 82A and 82B, respectively, which serves as a stationary portion that is mounted to the body 74. The actuators 76A and 76B further each include a piston 84A and 84B, respectively, which serves as an effector that is movable along a telescoping direction with respect to the corresponding cylinder 82A and 82B. The pistons 84A and 84B are operatively connected with the crank 78. As can be understood from FIG. 15, the telescoping direction of the actuator 76A is substantially parallel with the telescoping direction of the actuator 76B, and vice versa. The telescoping direction of the actuators 76 thus can be said to be substantially parallel with one another. Moreover, the actuators 76A and 76B are situated side by side. In this regard, it can be seen that the manipulator apparatus 68 includes a free end 85 that is situated at an end of the body 74 opposite the connections with the first and second links 70 and 72. The base 80 is situated adjacent the free end 85, and the actuators 76 both extend away from the crank 78 in a direction that is also away from the free end 85. It can be understood from FIG. 15 that rotation of the base 80 with respect to the body 74 is caused by the extension of one of the actuators 76 simultaneously with the contraction of the other of the actuators 76, which results in a coupling of two opposite forces being applied to opposite ends of the crank 78 simultaneously. The advantageous positioning and coincident actuation of the actuators 76 enables the free end 85 of the body 74 to be situated extremely close to the base 80, which advantageously enables the device 6 to have a desirably long reach along the axis of elongation 34 from the stand 69, as will be set forth in greater detail below. As can be understood from FIGS. 1, 16, and 17, by way of example, the tool 4 further includes a reciprocation apparatus 86 that is situated on the base 80 of the rotation apparatus 64. More specifically, the reciprocation apparatus 86 can be said to include a platform 88 that is situated on the base 80 and to further include a support 90 that is movably situated on the platform 88. The platform 88 can be said to include a first side 91A and a second side 91B opposite one another. The reciprocation apparatus 86 further includes a belt 92 that extends between the platform 88 and the support 90 and a mount 94 that is situated on the support 90 and which includes, for example, a Gimbal apparatus that is interposed between the support 90 and the device 6. The reciprocation apparatus 86 further includes a drive mechanism 96 that operatively extends between the platform 88 and the support 90. The reciprocation apparatus 86 further includes a plurality of retention wheels 98 that are rotatably situated on the platform 88 and that are engaged with the support 90. In the depicted exemplary embodiment, the retention wheels 98 are in two pairs, with one pair of the retention wheels 98 movably engaging and retaining therebetween a first portion of the support 90, and with the other pair of retention wheels 98 movably engaging and retaining therebetween another portion of the support 90. In a like fashion, the mount 94 includes a set of four positioning wheels 99 that are rotatably situated thereon and that are similarly arranged in pairs that are disposed at opposite sides of the support 90 and that engage therebetween two different portions of the support 90. More specifically regarding the support 90, it can be seen that the support 90 includes an elongated flange 100 that is elongated along an arcuate path of fixed radius and that is concave with respect to the platform 88, meaning that the radius of curvature of the flange 100 is in the same direction from the flange 100 as the direction in which the platform 88 is situated with respect to the flange 100. The flange 100 has a first end 101A and a second end 101B opposite one another. The first end 101A extends from the flange 100 in a direction generally away from the first side 91A of the platform 88, and the second end 101B extends from the flange 100 in a direction generally away from the second side 91B of the platform 88. The support 90 further includes a toothed rack 102 that is formed on the flange 100 and that includes a plurality of teeth that are engaged by the drive mechanism 96 to move the mount 94 among a plurality of positions with respect to the manipulator apparatus 60. For example, FIGS. 1, 3, and 19-20 depict what could be characterized as a centered position of the reciprocation apparatus 86 which, in the depicted exemplary embodiment, is wherein the mount 94 is situated as close as possible to the platform 88, wherein the mount 94 is situated centrally on the flange 100 an equal distance between the first and second ends 101A and 101B, and wherein the mount 94 overlies the platform 88. FIGS. 5-8 and 16 depict one extreme position of the reciprocation apparatus wherein the support 90 and the mount 94 (and thus the device 6) are situated as far as possible in one circumferential direction away from the frame 32. In the position of FIGS. 5-8, the first end 101A of the flange 100 is situated at a location spaced relatively farther away from the first side 91A of the platform 88 than the second end 101B of the flange 100 is spaced away from the second side 91B of the platform 88. In a like fashion, FIG. 17 depicts another extreme position of the reciprocation apparatus with respect to the manipulator apparatus 60 wherein the platform 90 and the mount 94 (and thus the device 6) are situated as far as possible in an opposite circumferential direction away from the manipulator apparatus 60. In the position of FIG. 17, the first end 101A of the flange 100 is situated at a location spaced relatively closer to the first side 91A of the platform 88 than the second end 101B of the flange 100 is spaced away from the second side 91B of the platform 88. That is, in FIG. 17 the second end 101B of the flange 100 is spaced farther away from the second side 91B of the platform 88 than the first end 101A of the flange 100 is spaced from the first side 91A of the platform 88. FIG. 21 depicts an intermediate position intermediate the centered position of FIG. 19, for example, and the one extreme position of FIG. 16, by way of example. It is understood that the reciprocation apparatus 86 is continuously movable among all positions between the one extreme position of FIG. 16, for instance, and the other extreme position of FIG. 17, by way of example, in order to move the mount 94 and thus the device 6 along the circumferential direction 19 between the two extreme positions represented by FIGS. 16 and 17. As can be seen in FIGS. 19 and 21, for example, the belt 92 has two locations of affixation that are indicated at the numerals 104A and 104B and which cause the belt 92 to form a closed loop that extends around a pair of pulleys indicated at the numerals 105A and 105B that are situated adjacent the opposite ends 101A and 101B of the flange 100. The belt 92 further has an additional location of affixation 104C wherein the belt 92 is affixed at approximately its midpoint to the platform 88. As can be understood from FIG. 22, the drive mechanism 96 includes a motor 106 situated on the platform 88 from which extends a shaft 108 and that is connected with a gear train 110 via an intermediate bevel drive 112. The gear train 110 includes a drive gear 114 that is toothed and that toothedly engages the rack 102 of the support 90. When the motor 106 is energized or is otherwise caused to have its shaft 108 rotate, the resulting movement of the drive gear 114 causes the support 90 to move with respect to the platform 88 since the platform 88 is affixed to the base 80 of the manipulator apparatus 60. Since the belt 92 is affixed at the location of affixation 104C to the platform 88, movement of the support 90, such as is indicated in FIG. 21, in a direction away from the centered position of FIG. 19 toward the one extreme position of FIG. 16 results in the tension in the belt 92 applying a force at the location of affixation 104A to the mount 94. Such force causes the mount 94 to move with its positioning wheels 99 along the longitudinal extent of the support 90 toward the first end 101A of the flange 100. Such movement of the mount 94 can also be said to be generally away from the first side 91A of the platform 88. For each incremental distance of movement of the support 90 with respect to the platform 88 along the circumferential direction 19, the mount 94 moves twice as far with respect to the platform 88 along the circumferential direction 19. This is accomplished by providing the belt 92 to extend about both the concave surface of the flange 100, i.e., the surface upon which the rack 102 is formed, and the convex surface of the flange 100 that is opposite thereto. For example, if the support 90 moves one inch along the circumferential direction 19 to the left of FIG. 21, this results in a portion of the belt 92 being pulled a distance of one inch at each of the concave and convex surfaces of the support 90, and since the belt 92 is affixed to the platform 88 at the location of affixation 104C, the mount 94 is thereby caused to move a total of one inch+one inch=two inches along the circumferential direction 19 in the leftward direction from the perspective of FIG. 21. The distance along the circumferential direction 19 that is traversed by the mount 94 in going between the extreme positions of FIGS. 16 and 17 is far greater than the length of the support 90 along the circumferential direction. While a certain portion of the support 90 must remain affixed between the pairs of retention wheels 98 on the platform 88, the geometry presented herein permits the mount 94 and thus the device 6 situated thereon to move through a distance along the circumferential direction 19 that is nearly twice the length of the support 90 along the circumferential direction 19. Moreover, the provision of the drive mechanism 96 in combination with the arrangement of the belt 92 enables the drive mechanism 96 to drive both the support 90 and the mount 94 with only a single drive mechanism 96. In order to receive the tool 4 into the BWR 10 for use therein, the manipulator apparatus 60 is first placed into its retracted position, such as is depicted generally in FIGS. 9-12. As can be understood from FIGS. 9-12, the reciprocation apparatus 86 and the device 6 mounted thereon are situated fully within the receptacle 44 when in the retracted position, thereby permitting the tool 4 to be longitudinally received in one of the fuel cells 22. In the retracted position, the longitudinal extent of the support 90 is generally aligned with the axis of elongation 34. The manipulator apparatus 60 is typically retained in the retracted position until the feet 38 have engaged the sockets 24 of the fuel cell 22 in which the tool 4 is received. Thereafter, the driver 68 can be operated, i.e., lengthened in the depicted exemplary embodiment, to move the manipulator apparatus 60 from the retracted position of FIGS. 9-12 to an extended position wherein the support 90 is situated at the exterior of the receptacle 44 with the longitudinal extent of the support 90 remaining generally aligned with the axis of elongation 34. Further thereafter, the actuators 76 of the rotation apparatus 64 can be operated to pivot the reciprocation apparatus 86 between the extended position and a deployed position wherein the support 90 has been rotated by the rotation apparatus 64 such that its longitudinal extent lies approximately transverse to the axis of elongation 34, such as is depicted generally in FIG. 4. In so doing, it may also be necessary to energize or otherwise actuate the motor 42 of the foot apparatus 36 to cause the frame 32 to be pivoted about its axis of elongation 30 with respect to the feet 38, such as is depicted generally in FIG. 2, in order to cause the arcuate profile of the platform 88 to become aligned with the arcuate profile of the interior surface 14 of the shroud 12. In this regard, it can be understood that the operation of the manipulator apparatus 60 and the pivot mechanism 40 between the position of FIGS. 9-12 and the position of FIG. 2 can be accomplished in generally any order so long as the driver 68 has been operated sufficiently that the support 90 is situated outside the receptacle 44. For instance, in a given situation it may be desirable to operate the pivot mechanism 40 first to cause the frame 32 to be oriented in the position depicted generally in FIG. 2, after which the driver 68 will be operated to cause the platform 90 to be fully situated outside the receptacle 44 while not yet being fully situated closely adjacent the interior surface 14. The rotation apparatus 64 may then be energized or otherwise operated to cause the base 80 to be rotated approximately 90 degrees to cause the support 90 to be oriented such that its longitudinal extent is oriented generally transverse to the axis of elongation 34. After this, the driver 68 can be further operated to advance the support 90 relatively closer to the interior surface 14 until the position that is depicted generally in FIG. 2 is achieved. It thus can be understood that such operations can occur in generally any order in order to achieve the positioning of FIG. 2 so long as the support 90 is in the extended position situated outside the receptacle 44 prior to the rotation apparatus 44 being energized or otherwise operated. FIG. 2 depicts the same centered position of the reciprocation apparatus 86 as FIGS. 1, 3, and 4, by way of example. By energizing or otherwise operating the drive mechanism 96, the reciprocation apparatus 86 can be caused to move from the centered position and between the extreme positions of FIGS. 16 and 17, which thereby causes the mount 94 and thus the device 6 situated thereon to be moved along the circumferential direction 19 between a plurality of different positions along the interior surface 14, i.e., along the circumferential direction 19 at a given vertical height from the perspective of FIG. 4. Once the reciprocation apparatus 86 has moved between the two extreme positions of FIGS. 16 and 17, for example, the elevator apparatus 52 can be energized or otherwise operated to move the manipulator apparatus 60 and thus the reciprocation apparatus 86 and the mount 94, as well as the device 6 mounted on the mount 94, to a vertically different position vertically above or below, from the perspective of FIG. 4, the previous vertical position. For example, the tool 4 may be initially deployed in the position depicted in FIGS. 2 and 4 with respect to the shroud 12, i.e., with the free end 85 extending from the stand 69 in a direction toward the feet 38, which is in a downward direction from the perspective of FIGS. 2 and 4, and which can be referred to as a second configuration of the manipulator apparatus 60. The elevator apparatus 52 may be operated to progressively move the reciprocation apparatus 86 in the downward axial direction 17 after each traversal by the reciprocation apparatus 86 between the extreme circumferential positions such as are depicted in FIGS. 16 and 17. Such circumferential movement alternately followed by axial movement results in the reciprocation apparatus 86 and thus the device 6 moving along successive circumferential sectors of the interior surface 14 moving in, for instance, a downward direction to eventually inspect a large circumferential sector of the shroud 12 extending from the position depicted generally in FIG. 4 downward to the horizontal weld 18. In this regard, it can be understood from FIG. 6 that the positioning of the manipulator apparatus 60 on the elevator apparatus 52 such that its free end 85 extends from the stand 69 in a direction generally toward the feet 38 enables the reciprocation apparatus 86 and thus the device 6 to be moved to an extremely low vertical position along the shroud 12. This enables inspection of the horizontal weld 18, by way of example. The tool 4 can thereafter be removed from the fuel cell 22 and the tool 4 can be partially disassembled to reorient the manipulator apparatus 60 on the elevator apparatus 52 in a first configuration, such as is depicted generally in FIG. 1, wherein the free end 85 of the manipulator apparatus 60 extends from the stand 69 in a direction generally away from the feet 38. The first and second configurations mentioned herein are not intended to suggest any particular order of operation. Repositioning the tool 4 in the fuel cell 22 with the manipulator apparatus 60 having been reoriented to be in the second configuration, such as is depicted generally in FIG. 1, enables the elevator apparatus 52 to be operated to cause the manipulator apparatus 60 and thus the reciprocation apparatus 86 and the device 6 to be moved vertically very high along the axial direction 17 to enable inspection of the shroud 12 in a region adjacent the top guide 26. By enabling the manipulator apparatus 60 to be switchable between the two configurations of FIG. 1 and FIG. 5, for example, the manipulator apparatus 60 is alternately positioned to enable the entire vertical extent of the shroud 12 to be accessible by the device 6, such as for inspection or for other purposes. It is reiterated that operation of the reciprocation apparatus 86 enables a wide swath along the circumferential direction 19 that is nearly twice the length of the support 90 along the circumferential direction 19 to be accessed by the mount 94 and thus the device 6 for purposes of inspection or otherwise while the tool 4 is received in a given fuel cell 22. A bail 116 situated at the top of the frame 32 enables the tool 4 to be connected with a lifting mechanism that lowers the tool into the relevant fuel cell 22 and removes the tool 4 therefrom. It can be understood that the computer system 28 is operable to perform all of the operations set forth above and to control the device 6, such as by detecting ultrasonic data therefrom during a testing operation or to otherwise control a different type of device 6 that otherwise interacts with the shroud 12. The configuration of the tool 4 and the reciprocation apparatus 86 thus advantageously enable rapid access to the interior surface 14 of the shroud 12 which enables inspection or other operations to be rapidly performed thereon. Other advantages will be apparent. While specific embodiments of the disclosed concept have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the disclosed concept which is to be given the full breadth of the claims appended and any and all equivalents thereof |
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claims | 1. An X-ray examination apparatus which includes an X-ray source ( 1 ) for emitting an X-ray beam ( 8 ) having a central X-ray extending along a central beam line ( 4 ), and an X-ray detector ( 2 ) for picking up X-ray images, where the X-ray detector ( 2 ) and the X-ray source ( 1 ) are rotatable together about an axis of rotation ( 3 ), and a calibration system ( 6 , 7 ) which is provided with a calibration phantom ( 6 ) and a calibration control unit ( 7 ) which is arranged to form separate calibration images for different, notably essentially opposed directions of the X-ray beam, and to determine the zero orientation of the X-ray source with the X-ray detector from differences between the positions in the individual calibration images of the same aspect of the imaged calibration phantom, where the central beam line ( 4 ) extends perpendicularly to the axis of rotation ( 3 ) in the zero orientation. 2. An X-ray examination apparatus as claimed in claim 1 , wherein the axis of rotation and the central beam line intersect in an isocenter ( 9 ), and claim 1 wherein the calibration phantom is positioned outside the isocenter so as to form the calibration X-ray images. 3. An X-ray examination apparatus as claimed in claim 2 , wherein the distance between the isocenter and the calibration phantom during the formation of at least one of the calibration X-ray images is larger than the distance between the X-ray detector and the calibration phantom. claim 2 4. An X-ray examination apparatus as claimed in claim 1 , wherein claim 1 the X-ray detector is arranged to derive electronic calibration image signals from the calibration X-ray images, the calibration control unit is arranged to suppress electronic parts of the electronic calibration image signals, the suppressed parts being situated symmetrically relative to the center of the calibration images, and to display masked calibration images on the basis of the partly suppressed electronic image signals and to calibrate the zero orientation on the basis of the masked calibration images. 5. An X-ray examination apparatus as claimed in claim 1 , wherein the calibration system includes a tower with a plurality of mating structural elements for supporting the calibration phantom. claim 1 |
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summary | ||
abstract | The present invention relates to a shutter system operable between an open position, and a closed position operable to avoid unintended exposure of a surface to radiant flux, wherein said shutter system comprises at least one pair of shields, and an axis for each shield, wherein a first axis is connected to an end part of a first shield, and coincides with the turning axis of the first shield, wherein a second axis, in the shape of an angled arm, is connected to an end part of a second shield and the turning axis of the second shield is parallel to the turning axis of said first shield and is arranged at a distance from the second shield. |
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description | 1. Field of the Invention The present invention relates generally to the analysis of fuel failure in nuclear reactors and, more particularly, to a method of analyzing pellet-cladding interaction (PCI) in Condition II events. 2. Background Information Commercial light water nuclear reactors (LWRs) generally include a plurality of cylindrical fuel elements which are grouped and secured together as separate fuel assemblies. The fuel assemblies are then arranged in an organized array to form the core of the nuclear reactor. As shown in FIG. 1, each nuclear fuel element or rod 2 contains a stack of fuel pellets 4 (e.g., without limitation, uranium dioxide) enclosed within a zircaloy cladding 6 having a first end 8 and a second end 10. The first and second ends 8, 10 are capped by end plugs 12, 14, as shown. Typically, a hold-down spring 16 or other suitable restraining mechanism maintains the position of the fuel pellets 4 by biasing the pellets 4 toward the bottom or second end 10 of the fuel rod 2. A fission gas plenum 18 is disposed near the top or first end 8, and a relatively small or narrow gap 20 is present between the fuel pellets 4 and the cladding 6. When the fuel 4 is burned, it expands (i.e., swells) in both the axial and radial directions. Such expansion begins to reduce the gap 20 between the cladding 6 and the fuel 4. Eventually, if the fuel 4 is allowed to continue to expand, the gap 20 is totally eliminated (not shown). With different thermal expansion coefficients, increases in power can cause significant stress on the cladding 6. Once this stress exceeds a threshold, the cladding will rupture, an event commonly known as pellet clad interaction (PCI). PCI cladding failure is a breach of the first radioactivity boundary in the system, and results in the fuel pellets 4 and radioactive fission products being exposed to the reactor coolant. Such a condition is, therefore, extremely undesirable. In an attempt to avoid cladding failure, the reactor protection system setpoints need to preclude operation that could result in PCI. The setpoints are validated using a detailed analysis of the normal operation (Condition I) and of events with moderate frequency (Condition II). More specifically, the analysis of Condition II events for fuel failure due to PCI is a regulatory requirement in some countries (e.g., without limitation, France). Condition II events include scenarios within the reactor core which are associated, for example, with an increase in nuclear reactivity and expressly include but are not limited to, boron dilution, rod withdrawal, and rod drop which is a condition in which one or more of the control rods unintentionally drop within the core. Known methods of performing the PCI analysis are based upon a brute force approach that requires the review and analysis of many different operational histories and the initiation of different transients at multiple times within each history, followed by the evaluation of the impact of such transients on each and every fuel rod within the reactor core. In view of the fact that there can be up to about 50,000 or more fuel rods within the reactor core, it will be appreciated that such an approach is extremely labor intensive, time consuming, and costly. In some circumstances such rod-by-rod analysis can take up to about two years or more. Additionally, if the core or operational limits of the reactor change, the entire analysis must be redone. There is a need, therefore, for a method of PCI analysis which is capable of accurately and efficiently evaluating and defining safe core operational guidelines in order to minimize the likelihood of PCI, without requiring a rod-by-rod brute force analysis. There is, therefore, room for improvement in PCI analysis of nuclear reactors. These needs and others are met by the present invention, which is directed to an improved method of analyzing pellet-cladding interaction (PCI) in Condition II events. As one aspect of the invention, a method of evaluating pellet-cladding interaction in a nuclear reactor core is provided. The nuclear reactor core has a reactor protection system, and includes a plurality of elongated fuel rods. The fuel rods each include a cladding tube surrounding a plurality of nuclear fuel pellets with a gap being defined between the nuclear fuel pellets and the cladding tube. The reactor protection system defines a number of operational limits for a plurality of parameters of the core, with the operational limits being based, at least in part, upon a predetermined set of technical specifications for the core. The method comprises the steps of: selecting a number of the parameters of the core to be analyzed; evaluating the selected parameters at a plurality of statepoints, each of the statepoints corresponding to a predetermined point in time for a predetermined core condition, wherein a set of the statepoints defines a history point, the history point being representative of the operational history of one or more of the fuel rods of the core; generating a model of an operating space of the core based, at least in part, upon the statepoints; selecting a loci of statepoints from the statepoints of the model wherein each of the statepoints of the loci of statepoints, when subjected to a predetermined transient, falls within the operational limits of the reactor protection system, the loci of statepoints defining a subset of the statepoints within the operating space of the core, the selection of the loci of statepoints being based, at least in part, upon one or more the history point; and evaluating the loci of statepoints for pellet-cladding interaction in response to the transient. The operating space may include those statepoints for which the reactor protection system would allow operation without forcing a shutdown of the reactor. The reactor protection system typically includes evaluation of parameters, such as, for example, total core power versus the axial flux difference (i.e., power in the top half minus power in the bottom half of the reactor core), inlet temperature, and primary system pressure. The analyzed operating space conservatively assumes the uncertainties in the measurement and, therefore, creates the largest possible operating space. It is the intent of the analysis to verify that the reactor is safe while within this possible operating space. The normal (i.e., Condition I) operating space is the space of allowable operation, as defined by the plant technical specifications. The technical specifications typically define limits which are monitored. Typical parameters which may be monitored include, for example and without limitation, the total core power, the core axial power distribution as defined by the core axial flux difference (i.e., power in the top half minus power in the bottom half of the reactor core), the control rod position, reactor vessel inlet temperature, and primary system pressure. The normal operating space is a subset of the possible operating space. The transient to which the statepoints are subjected may be representative of a Condition II event. All Condition II statepoints must be able to be associated with an initiating statepoint that is within the normal operating space. The parameters which are selected may be selected from the group consisting of xenon distribution, control rod position, power level, time in life, and inlet temperature. The method may further comprise: establishing a set of allowable core operating guidelines in order to provide for the safe operation of the core and to avoid pellet-cladding interaction; selecting a number of fuel rods of the core, the selected fuel rods having a controlling effect on the limits of the operating space; and evaluating the selected fuel rods for compliance with the guidelines. The xenon distribution in the core may be evaluated as a function of a delta xenon parameter and a xenon mid parameter, wherein the delta xenon parameter comprises the amount of xenon distributed in the top of the core minus the average amount of xenon in the bottom of the core, and wherein the xenon mid parameter comprises the average distribution of xenon in the middle third of the core minus the average xenon distribution of the entire core. The operational limits of the reactor protection system may include normal core operating limits and Condition II transient limits, and the step of generating a model of the core operating space may further comprise: modeling the core operating space as a discrete grid comprising the plurality of statepoints, selecting as the loci of statepoints, points on the grid which have a controlling effect on the limits of the operating space, and evaluating the controlling points on the grid with respect to the normal core operating limits and with respect to the Condition II transient limits. Historical data (e.g., history points and parameters, as defined herein) regarding the parameters for a set of the fuel rods may be provided, and the evaluation of the safety parameters may compare the values at the statepoint condition with the historical data. The method may further comprise the step of accepting or rejecting the statepoint for safe operation of the core. Accordingly, the method of the invention involves modeling and analyzing the reactor core using the discrete grid of the statepoints in order to accurately evaluate the fuel rods of the core for pellet-cladding interaction without requiring a multitude of core operational transients to be analyzed individually. The method may employ three-dimensional power distribution analysis to analyze the potential for pellet-cladding interaction in the fuel rods, and select steps of the method may be computer automated. As another aspect of the invention, a method of analyzing fuel in a nuclear reactor core is provided. The nuclear reactor core has a reactor protection system which defines a number of operational limits for a plurality of parameters of the core. The method comprises: selecting a number of the parameters of the core to be analyzed; evaluating the selected parameters at a plurality of statepoints, each of the statepoints corresponding to a predetermined point in time for a predetermined core condition, wherein a set of the statepoints defines a history point, the history point being representative of the operational history of one or more of the fuel rods of the core; generating a grid of the statepoints in order to accurately model an operating space of the core; selecting a loci of statepoints from the statepoints of the model wherein each of the statepoints of the loci of statepoints, when subjected to a predetermined transient, falls within the operational limits of the reactor protection system, the loci of statepoints defining a subset of the statepoints within the operating space of the core, the selection of the loci of statepoints being based, at least in part, upon one or more the history point; and evaluating the loci of statepoints in response to the transient. The loci of statepoints is a small subset of the total discrete grid and is uniquely determined by the initial point and each of the transients considered. The method may further comprise the steps of subjecting as the transient, a transient representative of a Condition II event; selecting as the loci of statepoints, statepoints associated with the Condition II event transient, the transient being initiated from each of the statepoints comprising the normal operating space of the core; analyzing the effect of the Condition II event on the selected parameters; and determining the potential for pellet-cladding interaction in response to the Condition II event. As employed herein, the phrase “normal operation” refers to operation of the nuclear reactor under standard operating conditions, commonly referred to as Condition I, wherein there is an absence of abnormal or unusual circumstances, such as, for example and without limitation, an accident event, a Condition II event, or any other abnormality having a significant impact on the operating parameters (e.g., without limitation, power distribution) of the reactor core. Normal operation is generally defined by limits on various key parameters as set forth in the plant technical specifications. Accordingly, the phrase “operating space” as employed herein, refers to the bounds of allowable, safe plant operation as dictated in part by the plant technical specifications for the particular nuclear plant at hand, and in part by the method of the invention. The operating space includes the range of core operation within which the reactor protection system will not be triggered so as to shut down the reactor. As employed herein, the phrase “Condition II event” refers to scenarios or circumstances relating to a nuclear reactor core where an unanticipated change in nuclear reactivity is experienced, and may include actual events or simulations of the same (e.g., transients applied to the core to replicate a Condition II event). Condition II events expressly include, but are not limited to, soluble boron dilution, unintentional control rod withdrawal, inlet temperature cooldown and control rod drop, which is a condition in which one or more control rods are dropped unintentionally within the core. Some, but not all, Condition II events result in a trip of the reactor protection system, thereby shutting down the reactor. As employed herein, the term “statepoint” refers to a particular point in time and/or a particular core operation (e.g., maneuver or transient). A set of statepoints corresponds to a “history point,” wherein the history point, in accordance with the invention, reflects the previous operational history of the individual fuel rods in the reactor core. The history point parameters include local parameters for a multitude of fuel rods. The local parameters include, for example and without limitation, local burnup, base local power level, local isotopic concentrations of various nuclei, and an effective cold gap. As employed herein, the phrase “loci of statepoints,” refers to a subset or reduced number of statepoints selected from the total plurality of statepoints comprising the model (e.g., grid) of the core operating space. The selected statepoints of the loci of statepoints subset, when subjected to a predetermined transient (e.g., without limitation, a Condition II transient), fall within the operational limits of the plant reactor protection system. As employed herein, the term “effective cold gap” refers to the magnitude of the gap or space between the fuel pellets and the fuel rod cladding at a nominal temperature with no power production by the fuel rod. In accordance with the present invention, effective cold gap data is tabulated (i.e., recorded) for a plurality of fuel rods at different history points throughout the life of the fuel, and is subsequently referenced as a key parameter in determining which fuel rods are acceptable for safe core operation. Thus, the effective cold gap of particular fuel rods serves as a history parameter for the generation of a history point, as defined herein. Traditional Pellet-Cladding Interaction (PCI) Analysis Pellet-cladding interaction (PCI) is a potential cause of fuel rod failure in light water reactors (LWRs). To prevent these failures, a variety of prior proposals for PCI have been implemented over the years. For example, more restrictive fuel preconditioning and maneuvering criteria have been developed to reduce the risk of PCI failure in fuel rods. Another prior proposal was the introduction of the concept of employing a zirconium liner fuel design. However, with the incorporation of the liner, utilities had a tendency to employ more aggressive operating strategies in an attempt to improve plant efficiency and, therefore override or surpass the new safety margins provided by the liner. A still further proposal was the implementation of smaller fuel with more rods in order to reduce the average fuel rod linear heat generation rate (LHGR) and provide greater margins to PCI failure. However, these margins were also commonly consumed by more aggressive core management which resulted in fuel being allowed to operate with higher local peaking factors. A more detailed history of PCI analysis, including a detailed discussion of modeling PCI in the reactor core, is provided, for example, in the published article, Modeling Pellet-Cladding Mechanical Interaction and Application to BWR Maneuvering, by Michel Billaux. That document is a publication of the company Framatome ANP, Inc. which has a place of business at 2101 Horn Rapids Road, Richland, Wash. To combat the problem of cladding failure due to PCI, fuel vendors perform analyses to demonstrate that the protection system prevents PCI and, previously noted, in some countries the analysis of Condition II events for fuel failure due to PCI, is a regulatory requirement. The traditional approach to performing such PCI analysis for Condition II events has been by way of the aforementioned brute force approach which involves looking at many different operational histories, the initiation of different transients at multiple different times within each of those histories, and finally evaluating the impact of such transients on each individual fuel rod (up to about 50,000 or more) within the reactor core. More specifically, conventionally a single statepoint is analyzed for a wide variety of power maneuvers (e.g., without limitation, percent reduction in power to a predetermined power level for a predetermined period of time; various rates of power reaction, including for example, ramp downs; and variations in the time duration for which the power is reduced (commonly referred to as the hold down time) and other plant operations under normal operating conditions, and data is recorded. This analysis, which in itself is laborious, is repeated for each of the 50,000 fuel rods. Making the analysis even more time-consuming and labor-intensive is the fact that numerous transients must be introduced at various statepoints within the maneuvers, in order to simulate the multiple possible Condition II events. Such transients are followed until their conclusion, for example, where a reactor protection system point (i.e., trip set point) is reached. The process is, therefore, highly multiplicative, as the foregoing analysis is repeated for each statepoint in the transient. Thus, all of the rods are analyzed in a brute force manner. To assist in the foregoing analysis and to determine which of the fuel rods can be safely operated within the core, a known or suitable computer code is employed. Notwithstanding this fact, it is still an extremely labor and time-intensive process, often taking up to two man-years of effort or more. As will now be discussed, the method of analysis of PCI of the invention is substantially different and provides a dramatic improvement. 3D FAC PCI Analysis in Accordance with the Invention The method of the present invention employs a three-dimensional final acceptance criteria (3D FAC) methodology to analyze the potential for PCI failures and thereby provides an accurate, systematic and comprehensive, yet efficient analysis of the core as a model of select statepoints, as defined herein, as opposed to analyzing each and every statepoint in the core. In other words, the method of the invention minimizes redundancy and unnecessary inefficient duplicative analysis of substantially similar statepoints and/or for statepoints for which the associated parameters of the fuel are well known. More specifically, the concept of 3D FAC in accordance with the invention, involves characterizing the core operating space by defining a discrete grid of statepoints characterized, for example, by the operational history, the reactor power, the control rod positions, the reactor inlet temperature and the xenon distribution which can be characterized using two or more summary parameters (e.g., without limitation, delta xenon and xenon mid, as defined hereinbelow). The evaluation of the power distribution statepoints is performed for several different times during the reload core operation in order to account for changes in the nuclear characteristics and fuel burn-up, which respectively affect the xenon distributions and the behavior of the core during the course of the transients. Xenon-135, as a direct fission by-product and also as a secondary by-product from the decay of iodine-135, is extremely parasitic to neutrons and, therefore, can adversely affect power distribution within the core as a function of time. This in turn can lead to significant local power changes which could possibly result in PCI. Establishing safe core operational limits with respect to PCI, involves a similar but more complex analysis. Specifically, for PCI Condition II events, it is the power increase that is of primary concern. Therefore, as will be discussed herein, defining the limit or maximum allowable threshold, or failure threshold, within which the core may be operated safely while minimizing the potential of a PCI failure, requires the evaluation of, for example and without limitation, the local power change in the limiting fuel rods associated with the possible initial and final statepoints at a variety of different burn-ups, and for multiple power histories. A pair of initial and final statepoints will have the same history and xenon condition, but the statepoints could have different initial and final core powers, inlet temperatures and/or control rod insertions. Normal core operation is not a single statepoint, rather it is an area or continuum that is a function of the core power. Typically, it has limits on the axial shape index (i.e., axial offset) and control rod insertion, both as a function of power, but it will be appreciated that other parameters can be defined in the technical specifications of the plant. Therefore, the evaluation of normal core operation involves the analysis of the core power distribution at a large spectrum of statepoints. The Condition II analysis then starts from each of the selected normal operation statepoints, and must evaluate the impact of the different transients on the fuel. As previously discussed, the traditional approach for this process is to model selected normal operation transients to generate the normal operation statepoints, and to then model the different Condition II transients from each of those statepoints in order to perform the Condition II analysis. However, it is difficult to generate transients that effectively cover the space of normal operation. Rather, a large number of duplicate or overlapping statepoints are frequently generated (see, for example, the overlapping data of FIG. 3). Recognizing these shortcomings, the method in accordance with the invention instead involves performing a direct combinatorial analysis using independent parameters, such as, for example, xenon distributions, control rod insertion, power level, and inlet temperature, in order to determine the core power distribution, and to evaluate the fuel with respect to the core protection limits. The limits include, for example, the maximum allowable core power as a function of the core axial offset or other suitable axial shape parameter and inlet temperature, or the maximum local power as a function of axial offset rod limits or other suitable axial shape parameter. Such limits are generated by evaluating multiple different fuel rods and then evaluating the maximum power that can be achieved before the limits are reached. In this manner, the failure threshold is defined as the point where the technological limit for PCI is reached in the analysis. As employed herein, the “technological limit” is defined based upon analytical comparisons of, for example, historical data from power ramp tests with fuel failures, and then defining the limit which best characterizes the data. This limit will be defined as a continuous function over the extent of the evaluation. Then, the evaluation of Condition II transients may take into account the time aspect of the transient. Accordingly, multiple different limits may be created depending on the specific transient being evaluated. In this manner, the evaluation of the potential operational statepoints enables an evaluation of the ability to meet the limits for the various Condition II transients. Based upon this analysis, the allowable operational space, or operating bounds, can be defined. In other words, the method of PCI analysis of the invention focuses on defining the actual operational space, and on using the data in a manner which characterizes the actual limits. Thus, the method provides a process for efficiently performing an accurate PCI analysis of Condition II events without requiring the evaluation of multiple different normal operation transients, multiple different Condition II transients based upon the normal operation statepoints, or the individual evaluation of each separate fuel rod within the core. The speed and efficiency of performing PCI analysis is, therefore, drastically improved over the known approach. This will be still further appreciated and understood with reference to the comprehensive EXAMPLE provided and described hereinbelow. More specifically, PCI analysis has traditionally involved taking, for example, three or four points in time in the cycle and going through a series of transients, such as, for example and without limitation, power reductions with various rod insertions, and then applying other transients (e.g., simulated Condition II events) at different points in time during the various transients. In other words, many variables were combined and compounded and modeled until operating limits were exceeded such that the reactor would shut down. Following the transients and Condition II events, conventional PCI analysis involved evaluating each individual fuel rod to perform a stress analysis as to the effect of the transient on the rod, and the likelihood of PCI to occur. A determination was then made as to whether or not each rod was suitable for safe operation in the core. The method of PCI analysis of the invention improves the analysis by focusing on two key parameters in order to define xenon conditions at various points in time, and then generate a model of the core based upon this information. The model comprises, for example, a computer generated surface function with a grid representing the two key xenon parameters (e.g., delta xenon and xenon mid). In this manner, core statepoints with different xenon distributions may be modeled and analyzed rather than following specific xenon transients. Various points on the grid are then taken and analyzed, for example, as to control rod position and core power level. For instance, as will be appreciated with reference to the xenon distribution graph of FIG. 3, statepoints in two different transients may have substantially the same xenon distribution but for different reasons. Accordingly, rather than following specific transients and then analyzing each time point of the transient, xenon distribution, control rod position and power are evaluated over the entire spectrum of possible values. Since the expected changes to these parameters during the various Condition II transients are known based upon pre-existing accident and Condition II analysis historical data, the results of the foregoing analysis can be compared to the known reference values embodied in that data in order to clearly define or confirm existing core protection system setpoints or bounds, to ensure safe operation. FIG. 2 shows a flow chart outlining the basic steps of the method of PCI analysis in accordance with the invention. Generally, the analysis begins with step 100 of selecting a number of core operating parameters to be analyzed, and step 110 of evaluating the parameters at a plurality of statepoints in order to generate multiple core histories (i.e., history points, as defined herein) for the operating cycle. A model of the operating space of the core is then generated in step 120, and a loci of statepoints is selected from the model and subjected to a transient or maneuver in step 130. Next, in step 140, the loci of statepoints is evaluated in response to the transient or maneuver. Core operating guidelines may then be established, and select fuel rods may be evaluated for compliance with the guidelines in steps 150 and 160, respectively. Finally, in step 170, the fuel is accepted or rejected for safe operation in the core. Looking now at each of the aforementioned steps in greater detail, it will first be appreciated that each of the statepoints in the analysis corresponds to a predetermined point in time for a predetermined core condition, with a set of the statepoints defining a history point, and wherein the history points are representative of the operational history of one or more of the fuel rods. These core histories reflect different operational scenarios, such as, for example and without limitation, extended reduced power operation and extensive load follow operation in addition to extensive operation at full power. Thus, the analysis includes the generation of the history points and history parameters for the fuel rods of interest. One of the history parameters utilized may be effective cold gap. More specifically, over time, the Zircalloy cladding 6 (FIG. 1) surrounding the nuclear fuel pellets 4 creeps down, and the fuel pellets 4 swell. There are also different temperatures within the various regions of the fuel and different thermal expansion coefficients for the different parts. Thus, at different points in the life of the fuel and under different core conditions, the gap 20 or spacing between the cladding 6 and the fuel 4 is different. To provide a commonality for analysis purposes, an effective cold gap is defined, which is the gap 20 which would exist if the fuel rod was uniformly at a nominal cold temperature such as, for example, 20° C. Thus, effective cold gap is a key parameter for determining what the power limit is for a particular fuel rod, and ultimately which fuel rods are acceptable for safe operation in the core, in accordance with the invention. Along with the generation of the core operating history, a PCI limit surface is created based upon the key history parameters. This PCI limit surface or grid will be utilized to evaluate multiple locations on a large set of fuel in order to determine if the fuel PCI limits, in accordance with the reactor protection system, are met. Thus, a map is provided which defines the maximum allowed power that would be permitted for a fuel rod node as a function of various key parameters (e.g., without limitation, effective cold gap). More specifically, step 110 involves selecting a number of the history points to be analyzed in detail. This selection will cover a range of times in the fuel cycle, and predetermined and selected potential core operating strategies. The key core parameters selected may include, for example and without limitation, core power level, control rod position for each controlling bank, and inlet temperature. The analysis also includes defining the range of xenon conditions and, in particular, the xenon distributions in the core, for each of the times in the fuel cycle. While the xenon distribution is a three-dimensional distribution throughout the reactor core, it can be characterized by two key parameters, delta xenon and xenon mid, as previously noted. The delta xenon, is the average amount of xenon distribution in the top of the core minus the average amount of xenon in the bottom of the core, and xenon mid, is the average amount of xenon in the middle third of the core (when the core is hypothetically divided into a top third, a bottom third, and a middle third) minus the average amount of xenon of the entire core. An example plot of delta xenon versus xenon mid for nine different transients for one point in the life of the fuel, the end of life (EOL) is shown in FIG. 3. By evaluating the xenon distribution, the range or bounds of the xenon parameters can be defined and the operating space of the core can be modeled. Thus, in step 110, the xenon conditions are selected which are to be used to model the operating space of the core in step 120. As shown in FIG. 2, this may be accomplished by way of step 122, generating a grid of statepoints to accurately represent the core operating space. Then, in step 130, select statepoints on the grid are identified and analyzed. More specifically, a loci of statepoints is selected wherein the loci of statepoints comprises a reduced number or subset of select statepoints which have a controlling effect on the limits of the core operating space. In other words, certain statepoints and, for that matter, certain fuel rods within the core, have a tendency to define the bounds (i.e., the margin to the reactor protection system limit) within which the reactor core may be safely operated without exceeding the limits (i.e., initiating a trip) of the reactor protection system. The determination of which statepoints are controlling or limiting can generally be made from a review of the operational histories of the fuel rods. In summary, the loci of statepoints generally comprises the subset of statepoints which, when subjected to a predetermined transient (e.g., without limitation, a predetermined Condition II transient), will not exceed the limits of the reactor protections system. In step 140, the loci of statepoints is evaluated in response to the transient. For example, the loci of statepoints which have been subjected to a Condition II transient are evaluated for pellet-cladding interaction. In this manner, representative statepoints can be analyzed as opposed to analyzing each and every statepoint associated with many different core transients. More specifically, as previously noted, and as will be appreciated with reference to the xenon distribution plot of FIG. 3, there are a large number of duplicative or redundant statepoints for the various transients. Recognizing this, the method of the invention involves selecting only certain controlling statepoints while continuing to accurately represent the entire range or bounds of the data which defines the core operating space. Thus, in the example of FIG. 3, the xenon statepoints are chosen to bound the xenon distributions which are generated in representative power transient evaluations. Analyzing the selected statepoints of the model generally involves checking effects on the power distribution. Specifically, in accordance with the invention, the selected statepoints are systematically analyzed, rather than actually running a plethora of transients at each statepoint in accordance with known PCI analysis methods. While this still produces a large number of cases (e.g., the number of power histories, times the number of points in the cycle, times the number of core power levels, times the number of different control rod locations, times the number of different xenon distributions, time the number of inlet temperatures, times any other suitable variations), this analysis can be performed very systematically, with each of these statepoints being evaluated to see if the fuel rods are acceptable within the designated safety criteria for the nuclear plant. More specifically, as shown in FIG. 2, in a step 150, core operating guidelines can be established in accordance with designated safety criteria for the nuclear plant to ensure safe operation of the fuel in the core, without pellet-cladding interaction. Then, in step 160, select fuel rods can be evaluated for compliance with such guidelines. The guidelines include safety criteria, such as, for example and without limitation, peak power within the rod, departure from nucleate boiling and various fuel rod criteria, such as, for example, the evaluation of margin to PCI. The evaluation of the fuel rods against their criteria involves the analysis of many, if not all, of the fuel rods within the nuclear reactor since they have different power histories and different local powers. Thus, in accordance with the invention, the most limiting or controlling fuel rod at each statepoint is used to define the margin to the limit. It will be understood that although the analysis in steps 140, 150 and 160 may indeed find statepoints which exceed the limits, those statepoints should be excluded by the core limits and protection system. Accordingly, a primary purpose of the analysis is to demonstrate that the core limits and protection are adequate to protect against fuel failure (e.g., without limitation, due to PCI). Thus, in steps 160 and 170 those statepoints which are within the normal operation limits, as defined by the plant technical specifications, are selected. Typical parameters which define normal operation include, for example and without limitation, the allowable region for the control rod insertion, the maximum allowable power and the allowable axial flux difference as a function of the core power level. It will, however, be appreciated that depending on the plant technical specifications, other parameters can be used to select the allowable Condition I statepoints. These normal operation statepoints then serve as initiator points for the various hypothetical Condition II transients, as previously discussed. In summary, the analysis involves selecting the resulting statepoints permitted by Condition II transients (e.g., without limitation, dropped rod; rod withdrawal; inlet temperature cooldown; soluble boron dilution) which were initiated from acceptable Condition I (i.e., normal operation) statepoints. The set of possible Condition II statepoints is then evaluated to determine if the predetermined criteria for preventing fuel failure (i.e., fuel integrity criteria) are met. The purpose of this analysis is to verify that the possible Condition II statepoints which do not meet the fuel integrity criteria, are not permitted by the reactor protection system. Thus, all normal operation and Condition II transients will not exceed the fuel failure limits. Data for the loci of statepoints, after, or in response to, the transient is compared to limits based upon historical data (i.e., history points and parameters, as defined herein), and the fuel rod is accepted or rejected for safe operation (e.g., avoidance of PCI) in the core. It will, therefore, be appreciated that steps 130 through 170 of the method can involve the application of any known or suitable plant maneuver or transient. Accordingly, the invention involves analyzing the core as an area or continuum by monitoring the change in power from one selected statepoint to another, rather than the conventional point-by-point or rod-by-rod approach which requires isolation of each rod and monitoring local change in power and effects thereof to see if acceptable PCI criteria are exceeded for that rod, and then repeating the entire process for all 50,000 rods. Therefore, the method of the invention not only accurately evaluates the full scope of the core operating space, but it also simultaneously greatly simplifies the analysis by significantly reducing (i.e., by several orders of magnitude) the overall number of statepoints which are selected, modeled, and analyzed, and still further drastically simplifies the analysis by avoiding numerous unnecessary or redundant transient analyses for each of the statepoints of the model. Thus, it will be appreciated that the invention provides a method which is generally as precise and accurate as traditional PCI analyses methods, if not more so, but also vastly reduces the labor, time and thus cost of the analysis. It will also be appreciated that the analysis in accordance with the invention is, of course, largely facilitated by the use of a suitable computer code. Specifically, the aforementioned model is generated in the code as a surface map or grid function representative of the core operating area and based, at least in part, upon the fuel rod histories (e.g., history points and parameters, previously discussed and defined herein) as a function of the aforementioned key rod parameters (e.g., without limitation, effective cold cap, local burnup and local power). At least steps 140 and 160 of the method can then be performed using the code to analyze the fuel rods to determine, for example, the maximum power change that can be handled before a particular rod will suffer from PCI. The method, or at least select steps thereof are, therefore, computer automated. In this manner, the 3D FAC, which is required by some plant operators, can be accurately, effectively, and efficiently accomplished while vastly reducing the amount of analysis required. The method of the invention will be still further understood with reference to the following EXAMPLE which is provided solely for the purpose of simplicity of illustration, and is not meant to be limiting upon the scope of the invention. Specifically, the EXAMPLE provides a comparison of the PCI analysis of a Condition II event in accordance with the known method of analysis described hereinbefore, as compared to the improved method of the invention. For the comparison, the same plant operating period (e.g., cycle), the same number of operational histories, and the same number of times within the operating period, are analyzed under both methods. Specifically, in both methods, about 2-3 operational histories were each analyzed at about 3-4 different times within the period. The two methods of analysis then diverge significantly, as will now be discussed. For the traditional approach, in addition to the foregoing steps, each of the 3-6 operational histories was then analyzed for between about 12-32 different normal operating maneuvers, and each maneuver was analyzed for about 30-60 time steps. This was followed by the application and analysis of about 4-8 Condition II transients starting at each normal operation statepoint. Each Condition II transient starting at a normal operation statepoint had to also be analyzed for about 10-150 time steps. The power history versus time for each of the foregoing steps was applied for each fuel rod in the computer code model. In other words, all of the foregoing steps, which are quite numerous and cumbersome, must be performed about 13,000 or more times. Finally, an evaluation of the fuel rod performance had to be done using a fuel rod analysis code that contains fuel rod stress analysis capabilities. In summary, the traditional approach involves a multiplicative combinatorial problem wherein each step has multiple options to consider and analyze. In all, between about 1 billon and about 72 billion cases must be analyzed. The method of the invention on the other hand, vastly reduced and simplified the analysis. Specifically, in the instant EXAMPLE, the nuclear core operating space model was determined as a function of the aforementioned selected parameters for different power levels about 5-7 times. Xenon distributions were evaluated about 25-40 times, and different control rod insertions were evaluated about 18-64 times. These analyses were performed with the Westinghouse Electric Company ANC code, which is a three-dimensional nuclear analysis code licensable from the Westinghouse Electric Company LLC having a place of business in Monroeville, Pa. It will, however be appreciated that any known or suitable alternative three-dimensional nuclear analysis code could be employed. Typical fuel rods were modeled and evaluated for multiple idealized operational profiles and characteristic history parameters and a limiting power surface were generated. The characteristic history parameters and the limiting power surface are functions of key fuel parameters (e.g., the local fuel burnup, and the effective cold gap). This model was then utilized in the nuclear analysis tool to create the history information for the selected fuel rods to be analyzed and to determine the acceptability of the local power transient with respect to PCI failure. The foregoing was done for each of the limiting or controlling fuel rods in the model, about 10-100 total times. Like the prior art approach, a combinational problem was generated and solved using the suitable computer code. However, the extent of the analysis was dramatically simplified. Specifically, in comparison with the aforementioned traditional approach which required a total of between about 1 billion and 72 billion cases to be analyzed, the analysis of the invention reduced this number tremendously to between about 135,000 to about 21.5 million cases. Accordingly, it will be appreciated that the method of the invention drastically reduces the duration of the analysis, as previously discussed, from about two years to a number of weeks. In addition, the discretation of the key core statepoint parameters allows the analysis to be performed automatically by the computer code, which eliminates much of the elapsed time traditionally required for the analysis. Referring again to FIG. 3, the method of the invention will be still further understood and appreciated. FIG. 3 shows a plot of Delta Xenon versus Xenon Mid, as previously defined herein, for nine different transients. Thus, the resultant plot of FIG. 3 illustrates the end of life (EOL) load swings resulting from the various transients. The transients include three ramp maneuvers wherein core power is slowly reduced or ramped down to a determined level (e.g., 30%, 50% and 70%) and then ramped slowly back up, and six other transients. By way of example, the 18-6, 30% transient noted in the legend of FIG. 3 refers to a transient wherein the core is operated for 18 hours at full power followed by a rapid decrease to 30% power for six hours. It will, however, be appreciated that any suitable transients and maneuvers other than those shown in FIG. 3 could be applied and analyzed without departing from the scope of the invention. The plot shows the Delta Xenon versus Xenon Mid for all of the statepoints for each of the transients. As shown, and as previously described, there is significant overlap, or close relationship and redundancy between many of the statepoints for the different transients. As noted, the method of the invention acknowledges this redundancy and utilizes it in order to efficiently and accurately model and analyze the core. In view of the foregoing, it will be appreciated that rather than applying the straight linear approach of the known PCI analyses, the method of the invention is substantially different, instead involving the modeling of core transients as a grid of selective statepoints of the core operating space combined with the historical data, and then analyzing the transients as a progression between different statepoints on the grid (i.e., combination of the various key parameters) or model to evaluate the impact of, for example, a particular Condition II event on PCI. It is in this manner that the PCI analysis, which would have taken up to about 2 man-years worth of labor, or more, using conventional brute force methods of analysis, can be accomplished using the combinatorial approach of the invention, in as little as three weeks or less. While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention which is to be given the full breadth of the claims appended and any and all equivalents thereof. |
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summary | ||
041837851 | claims | 1. A method for positioning and extracting a moderator structure made of separate spherical moderator elements and also nodules in and from a nuclear reactor of the molten salt type, said method comprising positioning operations and extracting operations, wherein the positioning operations include the steps of: (a) defining a core region of the nuclear reactor by a bottom wall and a lateral reflector, (b) feeding in bulk a quantity of said spherical nodules required for completely filing said core region and obtaining said moderator structure consisting in a stock of separate nodules applied in mutual contact in the three dimensions of the space and a lattice of interstices in said stock, (c) placing a top wall for closing said core region, and (d) introducing into said core region, said molten salt, the extracting operations including the steps of: (e) removing the top wall, and (f) extracting said nodules by way of a handling device. (a) defining a core region of the nuclear reactor by a bottom wall and a lateral reflector, (b) feeding in bulk a quantity of said spherical nodules required for completely filing said core region and obtaining said moderator structure consisting in a stock of separate nodules applied in mutual contact in the three dimensions of the space and a lattice of interstices in said stock, (c) placing a top wall for closing said core region, and (d) introducing into said core region, said molten salt, the extracting operations including the steps of: (e) Removing the top wall, and (f) extracting said nodules by way of a handling device wherein the step f consists in withdrawing the molten salt and in introducing within said core region a liquid having a higher density than that of the constituent material of the nodules in order to cause said nodules to float on said liquid and wherein said nodules are extracted from said liquid by means of a handling device designed to grip only the nodules aforesaid. (a) defining a core region of the nuclear reactor by a bottom wall and a lateral reflector, (b) assembling the moderator blocks on a temporary supporting rig so as to define said moderator structure, outside said core region and introducing said assembled structure into said core region and disassembling said blocks from said supporting rib, and extracting said supporting rig, (c) placing a top wall for closing said core region, (d) and introducing into said core region said molten salt, the extracting operations including the steps of: (e) removing the top wall, and (f) extracting said nodules by way of a handling device. 2. A method according to claim 1, wherein the positioning operations include the step of subjecting the moderator structure to vibration after the step (b). 3. A method for positioning and extracting a moderator structure made of separate spherical moderator elements and also nodules in and from a nuclear reactor of the molten salt type, said method comprising positioning operations and extracting operations, wherein the positioning operations include the steps of; 4. A method according to claim 3, wherein said nodules are of graphite and the liquid is molten lead. 5. A method according to claim 1, wherein said handling device consists in hydraulic and also pneumatic transfer means. 6. A method according to claim 1, wherein said handling device consists in jaws of the claw type. 7. A method for positioning and extracting a moderator structure made of separate prismatic shaped moderator blocks in or from a nuclear reactor of the molten salt type, said method comprising positioning operations and extracting operations wherein: the positioning operations include the steps of: 8. A method according to claim 7 wherein the step f of the method is carried out by the supporting rig itself. 9. A method according to claim 7 for positioning and extracting a moderator structure made of moderator blocks, each block being provided with a central channel wherein the supporting rig is constituted by a series of hollow rods on which are threaded the central channels of a plurality of blocks, said hollow rods being rigidly fixed to a top support plate and the blocks being locked in position on the corresponding hollow rod by means of a temporary locking member located at the bottom of said rods. 10. A method according to claim 9, wherein the temporary locking members are pneumatic. 11. A method according to claim 9, wherein the temporary locking members are mechanical. 12. A method according to claim 9, wherein the temporary locking member is a tie-wire which is passed through the hollow rod and closed in a loop against the external surface of said blocks or engaged within an adjacent hollow rod. 13. A method according to claim 7, wherein the step f consists in withdrawing the molten salt, and in introducing within said core region a liquid having a higher density than that of the constituent material of the nodules in order to cause said nodules to float on said liquid and wherein said nodules are extracted from said liquid by means of a handling device designed to grip only the nodules aforesaid. 14. A method according to claim 13, wherein the blocks are made of graphite and the liquid is molten lead. 15. A method according to claim 7, wherein the handling device consists in jaws of the claw type. 16. A method according to claim 3, wherein the positioning operations include the step of subjecting the moderator structure to vibration after the step (b). |
claims | 1. An x-ray window comprising:a support-frame encircling an aperture and having a top-side and a bottom-side, the top-side and the bottom-side parallel with respect to each other;a boron-film and an aluminum-film spanning the aperture of the support-frame;the boron-film having ≥90 weight percent boron throughout the entire boron-film, and having a near-side and a far-side opposite of each other;a hermetic-seal between and adjoining an outer-ring of the near-side of the boron-film and the top-side of the support-frame, the hermetic-seal is a direct bond between the boron-film and the support-frame and is free of the aluminum-film;the aluminum-film adjoins the near-side of the boron-film inside of the outer-ring;ThF≤1.25*(Th12+Th52), where ThF is a minimum thickness of all thin films spanning the aperture, Th12 is a minimum thickness of the boron-film in the aperture, and Th52 is a minimum thickness of the aluminum-film in the aperture; andan annular-film adjoining the bottom-side of the support-frame, having an aperture aligned with the aperture of the support-frame, and including ≥90 weight percent boron throughout the entire annular-film. 2. The x-ray window of claim 1, wherein the aperture of the support-frame is free of support ribs and 300 nm≤Th12≤1200 nm. 3. The x-ray window of claim 1, wherein the aperture of the support-frame is free of material of the support-frame. 4. The x-ray window of claim 1, wherein solid material in the aperture consists of thin films spanning the entire aperture. 5. The x-ray window of claim 1, wherein a maximum total thickness of all thin films in the aperture is ≤4000 nm. 6. The x-ray window of claim 1, wherein a percent thickness difference between the boron-film and the annular-film is ≤20%, where the percent thickness difference equals a difference in minimum thickness between the boron-film and the annular-film divided by a minimum thickness of the boron-film. 7. The x-ray window of claim 1, further comprising ≥0.05 weight percent hydrogen throughout the entire boron-film and the entire annular-film. 8. The x-ray window of claim 1, wherein the boron-film and the annular-film have an identical material composition. 9. An x-ray window comprising:a support-frame encircling an aperture and having a top-side and a bottom-side, the top-side and the bottom-side parallel with respect to each other;a boron-film hermetically-sealed to the top-side, spanning the aperture of the support-frame, the boron-film having ≥90 weight percent boron throughout the entire boron-film; andan annular-film hermetically-sealed to the bottom-side, having an aperture aligned with the aperture of the support-frame, and including ≥90 weight percent boron throughout the entire annular-film. 10. The x-ray window of claim 9, wherein ThF≤1.5*Th12, where ThF is a minimum thickness of all thin films spanning the aperture, and Th12 is a minimum thickness of the boron-film in the aperture. 11. The x-ray window of claim 9, further comprising an aluminum-film spanning the aperture of the support-frame; the aluminum-film having ≥50 weight percent aluminum throughout the entire aluminum-film; and the aluminum-film and the boron-film are the only solid structures spanning the aperture of the support-frame. 12. The x-ray window of claim 9, further comprising an aluminum-film spanning the aperture of the support-frame, the boron-film faces atmospheric pressure, and the aluminum-film faces a vacuum. 13. The x-ray window of claim 9, wherein a percent thickness difference between the boron-film and the annular-film is ≤20%, where the percent thickness difference equals a difference in minimum thickness between the boron-film and the annular-film divided by a minimum thickness of the boron-film. 14. The x-ray window of claim 9, further comprising ≥0.05 weight percent hydrogen throughout the entire boron-film and the entire annular-film. 15. The x-ray window of claim 9, wherein the boron-film and the annular-film have an identical material composition. 16. An x-ray window comprising:a support-frame encircling an aperture;a boron-film spanning the aperture and hermetically-sealed to the support-frame;the boron-film having ≥97 weight percent boron, ≥0.3 weight percent hydrogen, and a density of ≥2.04 g/cm3 and ≤2.24 g/cm3; andThF≤1.5*Th12, where ThF is a minimum thickness of all solid structures spanning the aperture and Th12 is a minimum thickness of the boron-film in the aperture. 17. The x-ray window of claim 16, further comprising:the support-frame has a top-side and a bottom-side opposite of each other;the boron-film is hermetically-sealed to the top-side; andan annular-film hermetically-sealed to the bottom-side, having ≥97 weight percent boron, ≥0.3 weight percent hydrogen, and a density of ≥2.04 g/cm3 and ≤2.24 g/cm3. 18. The x-ray window of claim 16, further comprising an aluminum-film adjoining an inner-side and a bottom-side of the support-frame. 19. The x-ray window of claim 17, wherein the boron-film faces atmospheric pressure and the aluminum-film faces a vacuum. 20. The x-ray window of claim 16, wherein the aperture is free of support ribs and 300 nm≤Th12≤1200 nm. |
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abstract | An X-ray computed tomography (=CT) apparatus (10) has a filter element (2) for attenuating an X-ray beam (1). The filter element (2) has a spatially varying X-ray absorption capability along a cross direction (y) which is perpendicular to both the beam axis (z) of the X-ray beam and to a rotation axis (x) of a gantry. The spatially varying X-ray absorption capability exhibits a maximum absorption along the cross direction (y) at a zero position (y0), wherein X-rays passing through the filter element (2) at the zero position (y0) intersect the rotation axis (x). The CT apparatus allows for further reduction of the radiation dose for an object to be investigated, while simultaneously retaining high image quality. |
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claims | 1. A method of plasma particle simulation for analyzing the behavior of a plasma particle in plasma generated in a cylindrical-shaped housing chamber included by a plasma processing apparatus by calculating the behavior of a superparticle which is a virtual particle representing a plurality of plasma particles, comprising:dividing a space within said cylindrical-shaped housing chamber into a plurality of cells;setting a weighting factor corresponding to the number of said plasma particles represented by said superparticle in each of said divided cells;setting superparticles in each of said divided cells using plasma particles contained in said divided cell and said set weighting factor; andcalculating the behavior of said superparticles in each of said divided cells;wherein a volume of each of said divided cells is set small in the vicinity of a peripheral portion of said cylindrical-shaped housing chamber, andsaid weighting factor is set small in said divided cell in the vicinity of the peripheral portion of said cylindrical-shaped housing chamber. 2. The method of plasma particle simulation according to claim 1, further comprising default-setting said plasma particles in each of said divided cells. 3. The method of plasma particle simulation according to claim 1, wherein a plurality of weighting functions representing a relationship between a distance of said divided cell from a solid wall surface and said weighting factor are prepared, one of said weighting functions is selected in said setting the weighting factor step on the basis of a state of plasma predicted to be generated within said cylindrical-shaped housing chamber, and said weighting factor is set in each of said divided cells using said selected weighting function. 4. The method of plasma particle simulation according to claim 3, wherein one of said plurality of weighting functions is based on a trigonometric function. 5. The method of plasma particle simulation according to claim 3, wherein one of said plurality of weighting functions is based on a power index-based function. 6. The method of plasma particle simulation according to claim 1, wherein an increase/decrease in the number of said superparticles is determined using a probabilistic measure when said superparticles move from one of said divided cells to another one of said divided cells adjacent thereto. 7. The method of plasma particle simulation according to claim 1, wherein a space within said cylindrical-shaped housing chamber is divided axisymmetrically with respect to the central axis thereof into the plurality of cells in said dividing step, and a smaller weighting factor is set in any of said divided cells located closer to said central axis in said setting the weighting factor step. 8. The method of plasma particle simulation according to claim 1, wherein the volume of each of said divided cells is set small in an area in which a sheath is generated. 9. A non-transitory computer-readable storage medium for storing a program, which when executed by a computer, causes the computer to implement a method of plasma particle simulation for analyzing the behavior of a plasma particle in plasma generated in a cylindrical-shaped housing chamber included by a plasma processing apparatus by calculating the behavior of a superparticle which is a virtual particle representing a plurality of plasma particles, said method comprising:dividing a space within said cylindrical-shaped housing chamber into a plurality of cells;setting a weighting factor corresponding to the number of said plasma particles represented by said superparticle in each of said divided cells;setting superparticles in each of said divided cells using plasma particles contained in said divided cell and said set weighting factor; andcalculating the behavior of said superparticles in each of said divided cells;wherein a volume of each of said divided cells is set small in the vicinity of a peripheral portion of said cylindrical-shaped housing chamber, andsaid weighting factor is set small in said divided cell in the vicinity of the peripheral portion of said cylindrical-shaped housing chamber. 10. A plasma particle simulator for implementing a method of plasma particle simulation for analyzing the behavior of a plasma particle in plasma generated in a cylindrical-shaped housing chamber included by a plasma processing apparatus by calculating the behavior of a superparticle which is a virtual particle representing a plurality of plasma particles, comprising:a cell division unit adapted to divide a space within said cylindrical-shaped housing chamber into a plurality of cells;a weighting factor setting unit adapted to set a weighting factor corresponding to the number of said plasma particles represented by said superparticle in each of said divided cells;a superparticle setting unit adapted to set superparticles in each of said divided cells using plasma particles contained in said divided cell and said set weighting factor; anda behavior calculation unit adapted to calculate the behavior of said superparticles in each of said divided cells;wherein a volume of each of said divided cells is set small in the vicinity of a peripheral portion of said cylindrical-shaped housing chamber, andsaid weighting factor is set small in said divided cell in the vicinity of the peripheral portion of said cylindrical-shaped housing chamber. 11. A plasma processing apparatus provided with a cylindrical-shaped housing chamber in which plasma is generated and a plasma particle simulator for implementing a method of plasma particle simulation for analyzing the behavior of a plasma particle in plasma generated in said cylindrical-shaped housing chamber by calculating the behavior of a superparticle which is a virtual particle representing a plurality of plasma particles, wherein said plasma particle simulator includes:a cell division unit adapted to divide a space within said cylindrical-shaped housing chamber into a plurality of cells;a weighting factor setting unit adapted to set a weighting factor corresponding to the number of said plasma particles represented by said superparticle in each of said divided cells;a superparticle setting unit adapted to set superparticles in each of said divided cells using plasma particles contained in said divided cell and said set weighting factor; anda behavior calculation unit adapted to calculate the behavior of said superparticles in each of said divided cells;wherein a volume of each of said divided cells is set small in the vicinity of a peripheral portion of said cylindrical-shaped housing chamber, andsaid weighting factor is set small in said divided cell in the vicinity of the d peripheral portion of said cylindrical-shaped housing chamber. |
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abstract | An apparatus for ultrasonically examining a weld in a nuclear steam supply system includes an elongated guide rod for positioning within a pipe of the nuclear steam supply system. An ultrasonic transducer is positioned at an end of the elongated guide rod. A collapsible shoe encloses the ultrasonic transducer. The collapsible shoe includes a biasing mechanism to allow the collapsible shoe to pass through the pipe while the pipe is at a first circumference and while the pipe is at a second circumference. The collapsible shoe continuously contacts the pipe to establish ultrasonic coupling for the ultrasonic transducer. |
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047598964 | claims | 1. In a coolant moderated nuclear reactor including a nuclear core positioned within a pressure vessel, said nuclear core comprising a plurality of fuel assemblies extending to the periphery thereof, said pressure vessel having at least one axial or circumferential weld thereon, a method for reducing the value of the neutron flux to which said welds are exposed comprising the steps of determining the areas of the core periphery causing each of said welds to be exposed to high neutron flux levels determining the axial and circumferential locations of the core causing each of said welds to be exposed to high neutron flux levels determining the amount of moderating displacer material taken from the group consisting of boron carbide, cadmium, indium, silver, or hafnium needed to reduce the amount of the high neutron fluxes to which said welds are exposed to acceptable levels at each of the core areas and axial locations positioning said displacer material in a parallel arrangement within said fuel assemblies at the core periphery substantially axially and circumferentially adjacent to said welds exposed to high neutron flux levels. 2. In a coolant moderated nuclear reactor including a nuclear core positioned within a pressure vessel, said nuclear core comprising a plurality of fuel assemblies extending to the periphery thereof, said pressure vessel having at least one axial or circumferential weld thereon, means for reducing the amount of neutron flux to which said at least one axial or circumferential weld is exposed, said neutron flux reducing means being positioned within the periphery of said nuclear core and interspersed within the fuel assemblies at the core periphery substantially axially and circumferentially adjacent to one or more of said at least one axial or circumferential weld, respectively, said flux reducing means comprising a plurality of parallel arranged moderator displacer rods which are made from a neutron absorber material taken from the group consisting of boron carbide, cadmium-indium-silver, or hafnium. 3. The apparatus of claim 2, wherein said displacer and absorber rods are attached to a common hub. |
claims | 1. A nuclear island comprising:a nuclear reactor including a nuclear reactor core comprising fissile material disposed in a reactor pressure vessel having a lower vessel head disposed below the nuclear reactor core;a lateral seismic restraint including:a vertically oriented pin attached to one of the bottom of the lower vessel head and a floor underneath the nuclear reactor, and a mating pin socket attached to the other of the bottom of the lower vessel head and the floor underneath the nuclear reactor, the pin being received within the pin socket; anda reactor core retention cooling system comprising one or more baffles disposed alongside the exterior surface of a lower portion of the reactor pressure vessel including at least the lower vessel head,wherein the one or more baffles define a lower inlet surrounding the lateral seismic restraint that is in fluid communication with both the exterior surface of the lower portion of the reactor pressure vessel and the floor underneath the nuclear reactor. 2. The nuclear island of claim 1 further comprising:a support base secured to the floor underneath the nuclear reactor, wherein the vertically oriented pin or mating pin socket is attached to the floor via the support base. 3. The nuclear island of claim 1 wherein the one or more baffles comprise:a cylindrical jacket surrounding the lower portion of the pressure vessel including the lower vessel head, the cylindrical jacket having a narrowed lower end defining a central plenum inlet containing the lateral seismic restraint. 4. The nuclear island of claim 3 wherein the reactor core retention cooling system further comprises:radial ducts configured to admit water into the central plenum inlet. 5. The nuclear island of claim 1 wherein the one or more baffles include thermally insulating material. |
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claims | 1. A collimator comprising:a pair of first plate members having a shielding property against a radiation and movable in a direction parallel to surfaces thereof, the pair of first plate members defining a radiation passing aperture by a spacing between respective opposed end faces;a pair of second plate members having a shielding property against a radiation and parallel to the pair of first plate members and movable in a direction parallel to surfaces thereof, the pair of second plate members having end faces opposed to each other in the shielding property, the pair of second plate members overlapping the pair of first plate members at least partially so as to block any other radiation than the radiation passing through the aperture;a pair of third plate members having a shielding property against a radiation and parallel to the pair of second plate members, the pair of third plate members having respective end faces opposed to each other with a predetermined spacing, the pair of third plate members overlapping the pair of second plate members at least partially so as to block any other radiation than the radiation passing through the aperture;an adjusting mechanism which adjusts the aperture by moving the pair of first plate members; anda follow-up mechanism which causes the pair of second plate members to move following the pair of first plate members with movement of the first plate members. 2. A collimator according to claim 1, wherein the adjusting mechanism is configured to move the pair of first plate members so as to be close to and away from each other. 3. A collimator according to claim 2, wherein the follow-up mechanism comprises:a rack provided in the first plate member;a gear provided in the second plate member rotatably and engaging with the rack; anda fixed rack provided in the moving direction of the second plate member and engaging with the gear. 4. A collimator according to claim 1, wherein the follow-up mechanism comprises:an arm member mounted at an intermediate portion thereof to the second plate member and rotatable about the mounting portion in a plane parallel to the plate surface;a groove formed in the first plate member and with which one end of the arm member is engaged, the groove permitting movement of the one end of the arm member in a direction perpendicular to the moving direction of the first plate member; anda groove formed in the third plate member and with which an opposite end of the arm member is engaged, the groove permitting movement of the opposite end of the arm member in a direction perpendicular to the moving direction of the second plate member. 5. A collimator according to claim 1, wherein the radiation is X-ray. 6. A radiation irradiator having a radiation source and a collimator for applying a radiation from the radiation source to an object through an aperture, the collimator comprising:a pair of first plate members having a shielding property against a radiation and movable in a direction parallel to surfaces thereof, the pair of first plate members defining a radiation passing aperture by a spacing between respective opposed end faces;a pair of second plate members having a shielding property against a radiation, parallel to the pair of first plate members, and movable in a direction parallel to surfaces thereof, the pair of second plate members having end faces opposed to each other, the pair of second plate members overlapping the pair of first plate members at least partially so as to block any other radiation than the radiation passing through the aperture;a pair of third plate members having a shielding property against a radiation and parallel to the pair of second plate members, the pair of third plate members having respective end faces opposed to each other with a predetermined spacing, the pair of third plate members overlapping the pair of second plate members at least partially so as to block any other radiation than the radiation passing through the aperture;an adjusting mechanism which adjusts the aperture by moving the pair of first plate members; anda follow-up mechanism which causes the pair of second plate members to move following the pair of first plate members with movement of the first plate members. 7. A radiation irradiator according to claim 6, wherein the adjusting mechanism is configured to move the pair of first plate members so as to be close to and away from each other. 8. A radiation irradiator according to claim 6, wherein the follow-up mechanism comprises:a rack provided in the first plate member;a gear provided in the second plate member rotatably and engaging with the rack; anda fixed rack provided in the moving direction of the second plate member and engaging with the gear. 9. A radiation irradiator according to claim 6, wherein the follow-up mechanism comprises:an arm member mounted at an intermediate portion thereof to the second plate member and rotatable about the mounting portion in a plane parallel to the plate surface;a groove formed in the first plate member and with which one end of the arm member is engaged, the groove permitting movement of the one end of the arm member in a direction perpendicular to the moving direction of the first plate member; anda groove formed in the third plate member and with which an opposite end of the arm member is engaged, the groove permitting movement of the opposite end of the arm member in a direction perpendicular to the moving direction of the second plate member. 10. A radiation irradiator according to claim 6, wherein the radiation is X-ray. |
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