Split (2)

train · 33.5k rows

patent_number stringlengths 0 9	section stringclasses 4 values	raw_text stringlengths 0 954k
	summary
	abstract	An object of the present invention is to provide a sample image forming method and a charged particle beam apparatus which are suitable for realizing suppressing of the view area displacement with high accuracy while the influence of charging due to irradiation of the charged particle beam is being suppressed.
048428086	claims	1. A nuclear fuel pellet collating system, comprising: (a) means for positioning a plurality of pellet supply trays and a plurality of pellet storage trays, said trays adapted to support pellets in multiple rows thereof, each supply tray being adapted to support in at least one row thereon a plurality of pellets of an enrichment different from the enrichments of pellets on at least some other of said supply trays, each storage tray being adapted to support in at least one row thereon a plurality of pellets of an enrichment different from the enrichments of pellets on at least some other of said storage trays; (b) a pellet collating line including a pellet input station, a pellet measuring and collating work station and a pellet output station in a serial arrangement thereof; (c) means for transferring one at time said supply trays between said tray positioning means and said input station and for transferring one at a time said storage trays between said tray positioning means and said output station; and (d) pellet collating means disposed adjacent said pellet collating line and being operable for moving pellets in the at least one row thereof onto said work station from a given one supply tray on said input station, for measuring a desired length of pellets on said work station and separating the measured desired length of pellets from the remaining pellets, if there be any, for moving the measured length of pellets from said work station onto a given one storage tray on said output station, and for moving the remaining pellets, if there be any, from said work station back onto the one given supply tray on said input station. a platform having a tray supporting region thereon; and clamping means mounted on said platform adjacent said region and being operable to move between an unclamping position in which a tray on said input station is unclamped relative to said platform region permitting transfer of the tray from and to said region and a clamping position in which said tray is clamped on said platform region. a pair of shafts each rotatably mounted to said platform along one of a pair of opposite sides of said region thereon; a plurality of hook members attached to each of said shafts for pivoting between said unclamping and clamping positions relative to said platform region upon rotation of said shafts; and an actuator mounted on said platform adjacent each of said shafts and coupled thereto, each of said actuators being extendable and retractable for rotating said shafts and pivoting said hook members between said clamping and unclamping positions. a platform having a tray supporting region thereon; and clamping means mounted on said platform adjacent said region and being operable to move between an unclamping position in which a tray on said output station is unclamped relative to said platform region permitting transfer of the tray from and to said region and a clamping position in which said tray is clamped on said platform region. a pair of shafts each rotatably mounted to said platform along one of a pair of opposite sides of said region thereon; a plurality of hook members attached to each of said shafts for pivoting between said unclamping and clamping positions relative to said platform region upon rotation of said shafts; and an actuator mounted on said platform adjacent each of said shafts and coupled thereto, each of said actuators being extendable and retractable for rotating said shafts and pivoting said hook members between said clamping and unclamping positions. a platform having separate upper and lower portions, said upper portion of said platform having a tray supporting region thereon; a weighing scales disposed below said upper portion of said platform; elevating means pivotally mounted on said lower portion of said platform and supporting said upper portion thereof above said scales, said elevating means being operable to move between a lowered position in which a tray is supported off said region of said platform upper portion by said weighing scales and a raised position in which the tray is supported off said scales by said upper portion of said platform. a pair of lift arms disposed at each of a pair of opposite ends of said platform and at their upper ends movable supporting said upper platform portion, each of the lift arms of said pair thereof at one platform end being pivotally connected at its lower end with the lower end of one lift arm of said pair thereof at the opposite platform end; a pair of shafts each rotatably mounted to said lower platform portion and mounting one of said pair of lift arms between the upper and lower ends thereof; and an actuator coupled to one of said shafts and being extendable and retractable for rotating said shafts and thereby pivoting said lift arms so as to raise and lower said upper platform portion relative to said lower portion thereof and said weighing scales. a platform having separate upper and lower portions, said upper portion of said platform having at least one elongated pellet supporting region defined therein; and elevating means pivotally mounted on said lower portion of said platform and supporting said upper portion thereof thereabove, said elevating means being operable to move to a lowered position in which said upper platform portion is lowered toward said lower portion thereof and said pellet supporting region on said upper platform portion is located at an elevation slightly below that of the one supply tray on said input station for facilitating movement of the pellets from said supply tray onto said work station, said elevating means also being operable to move to a raised position in which said upper platform portion is raised away from said lower portion thereof and said pellet supporting region on said upper platform portion is located at an elevation slightly above that of the one storage tray on said output station for facilitating movement of the pellets from said work station onto said storage tray. a pair of lift arms disposed at each of a pair of opposite ends of said platform and at their upper ends movable supporting said upper platform portion, each of the lift arms of said pair thereof at one platform end being pivotally connected at its lower end with the lower end of one lift arm of said pair thereof at the opposite platform end; a pair of shafts each rotatably mounted to said lower platform portion and mounting one of said pair of lift arms between the upper and lower ends thereof; and an actuator coupled to one of said shafts and being extendable and retractable for rotating said shafts and thereby pivoting said lift arms so as to raise and lower said upper platform portion relative to said lower portion thereof. a platform having at least a pair of elongated generally parallel spaced apart bar-like members adapted to support the pellets in the at least one row thereof on said work station and defining an open slot therebetween; at least one alignment member; and an actuator mechanism mounted on said platform below said bar-like members and coupled to said alignment member, said actuator mechanism being operable to move toward, away from, and along said platform for respectively projecting said alignment member upwardly through said slot and above said bar-like members, retracting said alignment member downwardly through said slot and below said bar-like members, and moving said alignment member along said slot toward and away from the pellets supported by said bar-like members to locate said alignment member in contact with a leading one of the pellets in the at least one row thereof to establish a zero position for measuring of the desired length of the pellets. (a) a pellet collating line including serially-arranged pellet input, work and output stations; (b) a plurality of mobile carts, some supporting pellet supply trays and others supporting pellet storage trays, said trays adapted to support pellets in multiple rows thereof, said pellets on a given one tray being of the same enrichment with enrichments of pellets on some trays being different from on other trays; (c) a tray positioning station located adjacent to said pellet collating line and defining positions in which are lodged said mobile carts; (d) tray transfer robot located between said pellet collating line and said tray positioning station, said robot being operable to transfer supply and storage trays one at a time between said respective carts at said tray positioning station and said respective input and output stations; (e) an input sweep head disposed adjacent said input station and being operable for sweeping pellets resting in multiple rows on a given one of said supply trays at said input station from said supply tray onto said work station; (f) a gripping and measuring head disposed adjacent said work station and being operable for measuring a desired length of pellets in the multiple rows thereof on said work station and then separating the measured desired length of pellets from the remaining pellets, if there be any; (g) an output sweep head disposed adjacent to said output station and operable for sweeping the measured lengths of pellets from said work station onto a given one of said storage trays at said output station; (h) one of said input sweep head, said gripping and measuring head and said output sweep head being operable for sweeping the remaining pellets, if any, in the multiple rows thereof from said work station back onto the given one of said supply trays at said input station. a platform having a tray supporting region thereon; and clamping means mounted on said platform adjacent said region and being operable to move between an unclamping position in which a tray on said input station is unclamped relative to said platform region permitting transfer of the tray from and to said region and a clamping position in which said tray is clamped on said platform region. a pair of shafts each rotatably mounted to said platform along one of a pair of opposite sides of said region thereon; a plurality of hook members attached to each of said shafts for pivoting between said unclamping and clamping positions relative to said platform region upon rotation of said shafts; and an actuator mounted on said platform adjacent each of said shafts and coupled thereto, each of said actuators being extendable and retractable for rotating said shafts and pivoting said hook members between said clamping and unclamping positions. a platform having a tray supporting region thereon; and clamping means mounted on said platform adjacent said region and being operable to move between an unclamping position in which a tray on said output station is unclamped relative to said platform region permitting transfer of the tray from and to said region and a clamping position in which said tray is clamped on said platform region. a pair of shafts each rotatably mounted to said platform along one of a pair of opposite sides of said region thereon; a plurality of hook members attached to each of said shafts for pivoting between said unclamping and clamping positions relative to said platform region upon rotation of said shafts; and an actuator mounted on said platform adjacent each of said shafts and coupled thereto, each of said actuators being extendable and retractable for rotating said shafts and pivoting said hook members between said clamping and unclamping positions. a platform having separate upper and lower portions, said upper portion of said platform having a tray supporting region thereon; a weighing scales disposed below said upper portion of said platform; elevating means pivotally mounted on said lower portion of said platform and supporting said upper portion thereof above said scales, said elevating means being operable to move between a lowered position in which a tray is supported off said region of said platform upper portion by said weighing scales and a raised position in which the tray is supported off said scales by said upper portion of said platform. a pair of lift arms disposed at each of a pair of opposite ends of said platform and at their upper ends movable supporting said upper platform portion, each of the lift arms of said pair thereof at one platform end being pivotally connected at its lower end with the lower end of one lift arm of said pair thereof at the opposite platform end; a pair of shafts each rotatably mounted to said lower platform portion and mounting one of said pair of lift arms between the upper and lower ends thereof; and an actuator coupled to one of said shafts and being extendable and retractable for rotating said shafts and thereby pivoting said lift arms so as to raise and lower said upper platform portion relative to said lower portion thereof and said weighing scales. a platform having separate upper and lower portions, said upper portion of said platform having at least one elongated pellet supporting region defined therein; and elevating means pivotally mounted on said lower portion of said platform and supporting said upper portion thereof thereabove, said elevating means being operable to move to a lowered position in which said upper platform portion is lowered toward said lower portion thereof and said pellet supporting region on said upper platform portion is located at an elevation slightly below that of the one supply tray on said input station for facilitating movement of the pellets from said supply tray onto said work station, said elevating means also being operable to move to a raised position in which said upper platform portion is raised away from said lower portion thereof and said pellet supporting region on said upper platform portion is located at an elevation slightly above that of the one storage tray on said output station for facilitating movement of the pellets from said work station onto said storage tray. a pair of lift arms disposed at each of a pair of opposite ends of said platform and at their upper ends movable supporting said upper platform portion, each of the lift arms of said pair thereof at one platform end being pivotally connected at its lower end with the lower end of one lift arm of said pair thereof at the opposite platform end; a pair of shafts each rotatably mounted to said lower platform portion and mounting one of said pair of lift arms between the upper and lower ends thereof; and an actuator coupled to one of said shafts and being extendable and retractable for rotating said shafts and thereby pivoting said lift arms so as to raise and lower said upper platform portion relative to said lower portion thereof. a platform having a multiplicity of elongated generally parallel spaced apart bar-like members adapted to support the pellets in the multiple rows thereof on said work station and defining a multiplicity of open slots therebetween; a multiplicity of alignment members; and an actuator mechanism mounted on said platform below said bar-like members and coupled to said alignment members, said actuator mechanism being operable to move toward, away from, and along said platform for respectively projecting said alignment members upwardly through said respective slots and above said bar-like members, retracting said alignment members downwardly through said slots and below said bar-like members, and moving said alignment members along said slots toward and away from the pellets supported by said bar-like members to locate said alignment members in contact with a leading one of the pellets in each of the multiple rows thereof to establish a zero position for measuring of the desired length of the pellets. 2. The system as recited in claim 1, wherein said pellet collating means includes means disposed adjacent said input station and being operable for moving pellets in the at least one row thereof onto said work station from the given one supply tray on said input station. 3. The system as recited in claim 2, wherein said pellet moving means disposed adjacent said input station is an input sweep head disposed above said input station and adapted to move toward, away from, and along said input station for sweeping the pellets onto the work station from the one given supply tray and for moving to and from a retracted position relative to said input station. 4. The system as recited in claim 1, wherein said pellet collating means includes means disposed adjacent said work station and being operable for measuring a desired length of pellets on said work station and separating the measured length of pellets from the remaining pellets, if there be any. 5. The system as recited in claim 4, wherein said pellet measuring means disposed adjacent said work station is a gripping and measuring head disposed above said work station and adapted to move toward, away from, and along said work station for measuring and separating the pellets on said work station and for moving to and from a retracted position relative to said work station. 6. The system as recited in claim 1, wherein said pellet collating means includes means disposed adjacent said output station and being operable for moving the measured length of pellets from said work station onto the one given storage tray on said output station. 7. The system as recited in claim 6, wherein said pellet moving means disposed adjacent said output station is an output sweep head disposed above said output station and adapted to move toward, away from, and along said output station for sweeping the measured length of pellets from said work station onto the one given storage tray and for moving to and from a retracted position relative to said output station. 8. The system as recited in claim 1, wherein said input station includes: 9. The system as recited in claim 8, wherein said clamping means includes: 10. The system as recited in claim 1, wherein said output station includes: 11. The system as recited in claim 10, wherein said clamping means includes: 12. The system as recited in claim 1, wherein said output station includes: 13. The system as recited in claim 12, wherein said elevating means includes: 14. The system as recited in claim 1, wherein said work station includes: 15. The system as recited in claim 14, wherein said elevating means includes: 16. The system as recited in claim: 1, wherein said work station includes: 17. A system for collating nuclear fuel pellets, comprising: 18. The system as recited in claim 17, wherein said input sweep head is disposed above said input station and adapted to move toward, away from, and along said input station for sweeping the pellets in the multiple rows thereof onto said work station from the one given supply tray and for moving to and from a retracted position relative to said input station. 19. The system as recited in claim 17, wherein said gripping and measuring head is disposed above said work station and adapted to move toward, away from, and along said work station for measuring and separating the pellets on said work station and for moving to and from a retracted position relative to said work station. 20. The system as recited in claim 19, wherein said gripping and measuring head is adapted to measure and separate the pellets on said work station simultaneously in two rows thereof. 21. The system as recited in claim 17, wherein said output sweep head is disposed above said output station and adapted to move toward, away from, and along said output station for sweeping the measured length of pellets in the multiple rows thereof from said work station onto the one given storage tray and for moving to and from a retracted position relative to said output station. 22. The system as recited in claim 17, wherein said input station includes: 23. The system as recited in claim 22, wherein said clamping means includes: 24. The system as recited in claim 17, wherein said output station includes: 25. The system as recited in claim 24, wherein said clamping means includes: 26. The system as recited in claim 17, wherein said output station includes: 27. The system as recited in claim 26, wherein said elevating means includes: 28. The system as recited in claim 17, wherein said work station includes: 29. The system as recited in claim 28, wherein said elevating means includes: 30. The system as recited in claim 17, wherein said work station includes:
	claims	1. A radiotherapeutic apparatus comprising:a source of radiation emitting a beam of therapeutic radiation having a width, anda collimator comprising a plurality of moveable elements arranged to limit the beam width by a variable amount, the collimator being moveable along an arc centered substantially on the radiation source and comprising means for moving the beam in a direction transverse to the beam width including means for sweeping the beam to deliver a therapeutic dose of radiation across a two-dimensional area of a patient. 2. A radiotherapeutic apparatus according to claim 1 in which the elements of the collimator are adapted to be adjusted as the collimator is moved. 3. A radiotherapeutic apparatus according to claim 1 in which the collimator comprises an array of moveable elements each adapted to selectively block a beam segment. 4. A radiotherapeutic apparatus according to claim 3 in which the elements are arranged in a linear array. 5. A radiotherapeutic apparatus according to claim 3 in which the elements are arranged in a 2*n array. 6. A radiotherapeutic apparatus according to any one of claims 3 to 5 in which the beam of radiation is emitted along a path passing through part of the array of moveable elements, and the moveable elements can take up one of two available positions, one located within the beam path and thus adapted to block the beam segment, and one located outside the beam path. 7. A radiotherapeutic apparatus according to claim 6 in which the collimator is adapted to move transverse to both a beam axis and an array length. 8. A radiotherapeutic apparatus according to claim 1 or claim 2 in which the collimator is a multi-leaf collimator. 9. A radiotherapeutic apparatus according to claim 8 in which the collimator moves transverse to both a beam axis and a length of leaves of the multi-leaf collimator. 10. A radiotherapeutic apparatus according to claim 1 or claim 2 in which the collimator comprises elongate leaves which can be moved into a path of the beam by a desired length. 11. A radiotherapeutic apparatus according to claim 10 in which two arrays of leaves are provided, one on either side of the beam, each having a plurality of leaves disposed in a generally parallel arrangement. 12. A radiotherapeutic apparatus according to claim 11 in which the collimator moves transverse to both a beam axis and a length of the leaves. 13. A radiotherapeutic apparatus according to claim 10 in which the collimator moves transverse to both a beam axis and a length of the leaves.
	description	The present application is relevant to U.S. patent application Ser. No. 11/311,278, filed Dec. 20, 2005 by Yuko Sasaki et al., based on Japanese Patent Application No. 2004-367153 filed on Dec. 20, 2004, the entire content of which is incorporated herein by reference. The present invention relates to an inspection technology for inspecting fine patterns in a semiconductor device, a photo mask, a liquid crystal device, and the like. More specifically, the invention relates to the inspection technology for inspecting circuit patterns floated on a wafer during the manufacturing step of the semiconductor device, using an electron beam. The inspection technology for the semiconductor device, photo mask, and liquid crystal device having fine circuit patterns is a very important technology for improvement in a manufacturing yield thereof. An outline of the technology will be described below using the inspection technology for a semiconductor wafer as an example. The semiconductor device and a liquid crystal display device, which will be hereinafter referred to as the semiconductor device, is manufactured by repeating the step of transferring a pattern formed on the photo mask on the semiconductor wafer using a lithography process and an etching process. Whether the lithography process, etching process, and other various processes are satisfactory or not and generation of foreign matter during the manufacturing process of the semiconductor device greatly affect the yield of the semiconductor device. It is therefore important to detect abnormality and occurrence of a fault early or in advance and feedback the result of detection to the manufacturing process. For this purpose, the method of inspecting a pattern on the semiconductor wafer during the manufacturing process has been traditionally carried out. As the method of inspecting a defect that is present on a circuit pattern on the semiconductor wafer, a defect inspection apparatus that irradiates white light onto the semiconductor wafer, and makes comparison among the circuit patterns of the same type in a plurality of large integrated circuits (LSIs) using an optical image obtained by the irradiation has been proposed and put to practical use. As the inspection method that uses the optical image, for example, JP-A-3-167456 discloses a method in which an optically illuminated region on a substrate is imaged by a time delay integrating sensor, and the obtained image of the optically illuminated region is compared with design information input in advance, thereby detecting a defect. JP-A-9-138198 discloses an inspection method in which laser light is irradiated onto the semiconductor wafer to detect diffracted light or scattered light, makes discrimination between the diffracted light from a regular circuit pattern and the scattered light from foreign matter or a defective portion of an irregular shape, thereby detecting the foreign matter or the defective portion alone. With finer geometries of the circuit pattern, a more complicated shape of the circuit pattern, and diversification of materials, defect detection by the optical image has become difficult. Accordingly, a method in which an electron beam image having a higher definition than that of the optical image is used to make circuit pattern comparison, for inspection, has also been proposed. As a method of making pattern comparison for inspection using the electron beam, J. Vac. Sci. Tech. B, Vol. 9, No. 6, pp. 3005-3009 (1991), J. Vac. Sci. Tech. B, Vol. 10, No. 6, pp. 2804-2808 (1992), JP-A-5-258703, U.S. Pat. No. 5,502,306, and JP-A-10-234543 disclose the method in which the electron beam having an electron beam current of 10 nA or more, which is 100 times or more the electron beam current of an ordinary scanning electron microscope (SEM) is irradiated onto a conductive substrate such as an X-ray mask, one of secondary electrons, reflected electrons, and transmitted electrons that are generated by the irradiation are detected, and an image formed from a signal of the detected electrons is compared with an adjacent comparable pattern, thereby automatically detecting a defect. The inspection method as described above will be referred to as an electron beam inspection method. In the electron beam inspection method, an image with a higher definition than that with an optical appearance inspection method or a laser inspection method can be obtained. Detection of minute foreign matter or a defect on a fine circuit pattern is thereby possible. In addition to that, it is also possible to detect conductivity or non/conductivity of the circuit pattern and an electric defect using potential contrast. The potential contrast indicates a surface potential difference which is caused by the influence of charge by electron beam irradiation and reflects the emission efficiency of the secondary electrons. The conductivity or non-conductivity of the circuit pattern and the electric defect such as a short circuit of wiring or a transistor is generated on the surface or the lower layer of the semiconductor wafer. The potential contrast and a technology that utilizes the potential contrast are described in the “Electron and Ion Beams Handbook” (THE NIKKAN KOGYO SHIMBUN, Ltd), pp 622-623. By applying the optical appearance inspection, the optical inspection method, and the electron beam inspection method to various minute circuit patterns of the semiconductor device or the like, detection of various defects that could not be detected or discriminated by the shape of the semiconductor wafer surface as well as defects such as foreign matter and a defective pattern shape have become possible. Such defects include an electric defect such as an open circuit or a short circuit in various transistors, and a conduction fault of an opening pattern. In the conventional electron beam inspection, the electron beam is irradiated during an inspection. Then, the secondary electrons or the reflected electrons generated by the irradiation are detected and converted into a signal, for the inspection. Irradiation of the electron beam is thus continued during the inspection. For this reason, when the surface of the wafer to be inspected is made of an insulating material and is easily subject to the influence of charge, or when a structure floated from the substrate is formed on the wafer to be inspected and charged electrons tend to be accumulated on the floated structure, the charged electrons resulting from the charge are accumulated on the insulating material during the process of the inspection. The charged potential of the surface of the wafer will therefore be changed from an initial state. When the charged potential is changed, the focusing position or irradiating position of the electron beam will be changed. Thus, a magnification for an electron beam image obtained during the inspection does not become accurate. Further, a positional drift or a focusing deviation is generated, so that the quality of the electron beam image obtained during the inspection will be changed. Hence, it has become difficult to continue the inspection with the same sensitivity and accuracy as those in the initial stage of the inspection. Assume that an electron beam irradiating condition is changed in conjunction with the charged potential of the surface of the wafer to be inspected, when the charged potential changes. Then, the same electron beam image quality can be obtained. For this purpose, it is necessary to measure the charged potential of the wafer to be inspected real time during the inspection. It is therefore difficult to measure the charged potential real time based on the electron beam image alone. Further, it is possible to obtain the electron beam image of the same quality by correcting the focus and irradiating position of the electron beam irradiation whenever the quality of the electron beam image is changed during the inspection. However, when frequent suspension of the inspection and frequent focusing and positional alignment are performed on the wafer to be inspected, the time required for the inspection will become longer. Hence, speeding up of the inspection has become difficult, which leads to an increase in the manufacturing cost of the semiconductor device. Further, by setting an inspecting condition that causes a less change in the charged potential when the inspecting condition is set, the inspection of the semiconductor device using a stable image becomes possible. However, to do so, a method of performing the inspection for a long time using the set condition, checking presence or absence of a drift in the image, and obtaining an optimal inspecting condition was employed. An enormous time was therefore required for determining the optimal inspecting condition. In the conventional electron beam inspection, the electron beam is irradiated onto the wafer to be inspected during the inspection. Then, the secondary electrons or the reflected electrons generated by the electron beam irradiation are detected and converted into a signal, for the inspection. Irradiation of the electron beam is thus continued during the inspection. For this reason, when the surface of the wafer to be inspected is made of an insulating material and is easily subject to the influence of charge, or when a structure floated from the surface is formed on the wafer to be inspected and charged electrons tend to be accumulated on the floated structure, the charged electrons are accumulated on the insulating material during the process of the inspection. The quality of the electron beam image is not therefore stabilized. The conventional arts described above did not refer to a method of addressing this problem, or the method of obtaining the image without changing the charged state of the wafer during the inspection. An object of the present invention is therefore to provide a technology for inspecting patterns of a semiconductor device or the like, which can reduce the influence of charge on a wafer to be inspected during an inspection. This technology can be applied to the wafer to be inspected having a structure floated from the substrate thereof which is easily subject to the influence of the charge and charged electrons tend to be accumulated thereon. An apparatus for inspecting patterns according to the present invention including means for irradiating an electron beam onto the surface of a specimen with one of the patterns formed thereon, detection means for detecting a signal generated from the specimen, and means for imaging the signal detected by the detection means, the apparatus further including: means for changing the potential of the specimen or the potential of an electrode provided on a side, with respect to the specimen, where the electron beam is irradiated; means for changing the potential of the specimen or the potential of the electrode, thereby obtaining an electron beam image at each potential; and means for performing numeric conversion on information indicating contrast of the electron beam image or brightness of the electron beam image, for display. It is arranged that the potential of the specimen or the potential of the electrode can be arbitrarily set within a predetermined range. Then, there is provided means for setting the potential within the range where the charged potential of the surface of the specimen to be inspected is changed from positive to negative, obtaining the electron beam at each of plurality of potentials, and performing numeric conversion on image information, for display. A method for inspecting patterns according to the present invention includes the steps of: irradiating an electron beam onto a surface of a specimen with one of the patterns formed thereon and scanning the specimen; detecting a signal secondarily generated from the specimen by the electron beam; imaging the detected signal, for display; changing the potential of the specimen or the potential of an electrode provided on a side, with respect to the specimen to be inspected, where the electron beam is irradiated, thereby obtaining an electron beam image at each potential; and performing numeric conversion on information indicating contrast of the obtained electron beam or brightness of the obtained electron beam image, for display. Further, from electron beam image information obtained when the potential of the electrode above the specimen is changed, a point of change with brightness of the electron beam image starting to decrease is selected as an inspecting condition, for display, or set as the inspecting condition. Further, the potential of the specimen or the potential of the electrode is extensively and coarsely changed in several stages, thereby obtaining the electron beam image in each of the stages. The point of change with the brightness of the obtained electron beam image starting to decrease is obtained from information on the obtained electron beam image. Then, the potential is changed in finer stages in the vicinity of the point of change, thereby obtaining the electron beam image in each of the finer stages again. Then, the point of change is obtained again from information on the electron beam image obtained again. An optimal inspecting condition can be thereby set with high efficiency and with high accuracy. Assume the specimen (or substrate) such as the semiconductor device, having a fine circuit pattern formed thereon, or the wafer to be inspected in particular, of which the surface of the substrate is covered with an insulating film or which has the circuit pattern floated from the substrate. Then, using the technology described above, the potential of the substrate or the potential of the electrode for limiting charge, provided on the side of an electron beam source for irradiating the electron beam with respect to the substrate is determined so that a so-called state of equilibrium is maintained. In the state of equilibrium, the number of electrons pulled back from the substrate maintains equilibrium with the number of electrons returned to the substrate. Then, by setting this potential as the inspecting condition, the influence of charge on the specimen can be reduced. According to the present invention, even for the wafer to be inspected that is easily subject to the influence of charge, it becomes possible to set the optimal inspecting condition for implementing stable inspection easily and with high accuracy. As a result, it becomes possible to perform highly sensitive inspection of a defect on the wiring test pattern which has been hitherto difficult to identify the location of the defect therein. Further, when setting the optimal inspecting condition, conventionally, the defect detection sensitivity of the inspection and a set time for the inspection were varied according to the skill and the experience of an operator. On contrast therewith, according to the present invention, the optimal inspecting condition can be set in a short time. Accordingly, the time required for the operator to perform the inspection can be saved. A waiting period for products is also greatly reduced, so that a TAT (turnaround time) for detecting occurrence of a fault can be reduced. As described above, by providing the technology for inspecting the wiring step of the semiconductor device with high sensitivity and with high accuracy, the contents of a fault in the wiring step, which are important during the manufacturing process of the semiconductor device can be detected early. Further, information on the location and the size of the defect which is the cause of the fault necessary for taking countermeasures against the fault can be obtained substantially at the same time as the inspection. The TAT required until the countermeasures are taken can be thereby reduced, thus resulting in contribution to improvement in the yield and productivity of the semiconductor device. Other objects, features and advantages of the invention will become apparent from the following description of the embodiments of the invention taken in conjunction with the accompanying drawings. A technology of inspecting patterns according to an embodiment of the present invention will be described in detail with reference to drawings by taking inspection of a circuit pattern on a semiconductor device as an example. First, before the embodiment of the present invention is described, the principle underlying the technology of inspecting the semiconductor device according to the present invention will be described in detail. The technology of inspecting presence or absence of a defect in a pattern such as the circuit pattern of the circuit having a structure floated from a substrate using an electron beam will be described, taking the circuit pattern of the semiconductor device formed on a wafer as an example. FIG. 1 is a diagram showing an example of a configuration of an apparatus for inspecting the circuit pattern according to an embodiment of the present invention. The apparatus for inspecting the circuit pattern in this embodiment is roughly constituted from an electron optical system, a stage mechanism system for mounting the wafer thereon or moving the wafer therefrom, a wafer carrying system for loading the wafer there onto, a vacuum exhaust system for making the apparatus within a chamber to be in a high vacuum state, a control system for controlling respective units of the apparatus, an image processing system for performing processing on an observed image, and an operating system to be operated by a user. Details of the configuration in FIG. 1 will be described later. An example of a structure of the wafer to be inspected will be described with reference to FIGS. 2 to 6. In this embodiment, the wafer with a metal wiring test pattern formed on a Si substrate thereof is employed as the wafer to be inspected. FIG. 2 is a diagram showing an example of an overall configuration of the metal wiring test pattern. As shown in FIG. 2, a test pattern 2 is constituted as a group of a lot of blocks 2-1. From both sides of the test pattern 2, wirings 2-2 are extended, and one ends of the wirings 2-2 are connected to signal measuring pads 2-3. FIG. 3 is a diagram showing an example of a typical wiring configuration. As shown in FIG. 3, the pattern may be constituted from one long wiring. Alternatively, the pattern may be constituted from alternating comb-tooth patterns as shown in FIG. 4, or the pattern may be constituted from a contact chain obtained by connecting isolated wirings on two layers using via holes between the layers. All of these wiring test patterns are isolated from the Si substrate by an insulating film, thus each forming a so-called floating structure. FIG. 6 is a perspective view of the contact chain shown in FIG. 5. As shown in FIG. 6, an inter-layer insulating film 6-3 is formed on a Si substrate 6-4. On the inter-layer insulating film 6-3, a contact chain pattern 6-1 is formed. Though one of signal measuring pads 6-2 is shown in FIG. 6 for convenience of description, the signal measuring pads 6-2 are arranged on both sides of the pattern 6-1. Assume that a non-conducting defect 6-5 is present in a via hole for conduction in such a pattern, for example. Then, when a probe is applied to both ends of the signal measuring pad 6-2 to measure electrical characteristics, the value of resistance differs from a case where there is no defect. By checking this resistance value, presence or absence of a fault can be inspected. For the patterns in FIGS. 3 and 4, same resistance value measurement is carried out. When a wire break occurs in the wiring of the pattern in FIG. 3, the resistance value of the pattern becomes higher than that of a normal pattern. In the pattern in FIG. 4, the two comb-tooth patterns are insulated. Accordingly, when a short circuit occurs in this pattern, the resistance value becomes low. FIG. 7 is a diagram showing an example in which the measurement has been carried out. This embodiment shows the example in which the measurement of the contact chain has been carried out. The normal contact chain pattern shows the resistance value of an order of 106Ω, and the resistance values of 107Ω or more are shown as faults. By measuring the resistance as described above, presence or absence of a defect can be detected. In FIG. 7, locations colored in gray shows the locations of defective pattern portions. It cannot be known, however, where the defect has occurred in the test pattern. For this reason, it is difficult to trace down the contents of the defect and the cause of the defect. Thus, it would take much time to devise countermeasures against the defect. An inspection method of identifying the location of the defect is therefore required. A technology capable of identifying a faulty location as well will be described below. By performing inspection using the inspection apparatus shown in FIG. 1, the location of a defect can be identified by using potential contrast. FIGS. 8 to 10 show electron beam images obtained by measurement using the inspection apparatus in FIG. 1 and shows the electron beam images when defects have occurred. In the case of the test pattern in FIG. 3, when an electron beam is irradiated along wiring, the charged potential of the test pattern changes at both ends of the wiring with a wiring break portion 8-1 acting as a boundary between the both ends. The electron beam image obtained by observing this change becomes the one as shown in FIG. 8 as a potential contrast image. The location of the defect 8-1 can be estimated based on this potential contrast image. In the case of the pattern shown in FIG. 4, even if the wirings of the pattern are short-circuited, the electric potential change does not occur. Accordingly, brightness of a defect in this pattern does not change in the form of the potential contrast. However, a short-circuit failure occurs between the wirings. Thus, using a change in the contrast between the wirings, or a contrast between a defective portion 9-1 and a wiring 9-2 as shown in FIG. 9, the location of the defective portion can be estimated. In the case of the pattern shown in FIG. 5, by irradiating the electron beam in a direction in which the contact chain is connected, a defect portion 10-1 manifests itself as the potential contrast and becomes a circle shown in FIG. 10, as in the case of the pattern in FIG. 3. As described above, by using the electron beam image, the defective portion can be made to manifest itself. When the entire surface of the wafer is inspected, the electron beam is continuously irradiated as shown in arrows and a zig-zag arrow shown in a large circuit in FIG. 11. Accordingly, electric charges are accumulated on the surface of the wafer, so that the charged state of the surface of the wafer sometimes changes from the charged state of the surface of the wafer when inspection has been started, as shown in FIG. 12. FIG. 12 is a graph schematically showing a change of the charged potential of the surface of the wafer over time. The horizontal axis of the graph represents time, while the vertical axis of the graph represents the charged potential of the surface of the wafer. Since the focusing condition of electron beam irradiation differs between an initial image 12-1 and an image 12-2 showing a state in which the electric charges are accumulated, a manner in which a defect is seen is also changed. Thus, it can be seen that detection sensitivity of the defect is reduced. The inventor of the present invention conceived that, by performing the inspection with an irradiating condition that does not cause a change in the charged state of the wafer surface, the problem associated with the change in the charged potential over time could be solved. Referring again to FIG. 1, the inspection apparatus for the semiconductor device in this embodiment will be described in detail. As shown in FIG. 1, the electron optical system includes an electron gun 1-1, draw-out electrodes 1-2 and 1-5, a condenser lens 1-14, a blanking deflector 1-29, a stop 1-8, deflectors 1-15 and 1-11, an objective lens 1-16, a charge control electrode 1-17, an ExB deflector 1-9, reflection boards 1-27, a detector 1-25, and a power supply for charge control electrode 1-24 capable of applying an adjustable voltage to the charge control electrode 1-17. Voltages are supplied from power supplies for draw out electrode 1-3 and 1-6 to the draw-out electrodes 1-2 and 1-5. In order to prevent contamination of the stop 1-8 and a longer operating life of the stop 1-8, a heater for stop 1-10 is provided. A signal is sent to the blanking deflector 1-29 from a blanking signal generating unit 1-30, so that an electron beam 1-4 is deflected to prevent passage through the aperture portion of the stop 1-8. Irradiation of the electron beam 1-4 onto a wafer 1-12 is thereby prevented. The stage mechanism system includes an XY stage 1-18, an insulating layer 1-20, a holder 1-19 for mounting the wafer 1-12 thereon, and a retarding power supply 1-13 capable of applying a zero or negative voltage to the wafer 1-12 or substrate. A position detector using laser measurement is mounted on the XY stage 1-18. The control system includes a signal detection system control unit 1-23, a beam deflection correction control unit 1-40, an electron optical system control unit 1-42, and a mechanism and stage control unit 1-43. Irradiation of the electron beam 1-4 onto the wafer 1-12 causes a signal generated from the wafer to strike one of the reflection boards 1-27, thereby generating a secondary signal 1-28. This signal is detected by the detector 1-25 and amplified by a detection signal amplifier 1-31. The amplified analog signal is converted to a digital signal by an A/D converter 1-32 and transmitted to a signal processing unit 1-33 in an image processing system 1-26. The signal detection system control unit 1-23 can generate a clock frequency, and thereby can change a timing in which the secondary signal is generated. The beam deflection correction control unit 1-40 controls voltages to be applied to the deflectors 1-15 and 1-11, thereby controlling a deflection amount, deflection speed, and deflection direction of the electron beam 1-4. The electron optical system control unit 1-42 controls the draw-out electrodes 1-2 and 1-5, condenser lens 1-14, and blanking signal generating unit 1-30. The electron optical system control unit 1-42 adjusts the current value of the condenser lens 1-14 in particular, thereby controlling the current of the electron beam 1-4. The image processing system 1-26 includes a signal processing unit 1-33, a first image memory 1-34, a second image memory 1-35, a comparison operation unit 1-36, a defect determination unit 1-37, and a retarding voltage control unit 1-41. The operating system includes an operation screen, an operating unit 1-38, and an image and inspection data storage unit 1-44. By changing a voltage to be applied to the charge control electrode 1-17 provided above the wafer 1-12 (on the side of the electron gun 1-1) by the power supply for charge control electrode 1-21, the amount of secondary electrons which are generated by irradiation of the electron beam onto the wafer 1-12 and will reach the detector 1-25 can be adjusted. The reference numeral 1-3 designates a power supply for draw-out electrode. The reference numeral 1-4 designates an electron beam. The reference numeral 1-5 designates a draw-out electrode. The reference numeral 1-7 designates a condenser lens. The reference numeral 1-8 designates a stop. The reference numeral 1-10 designates a heater for stop. The reference numeral 1-24 designates a power supply for charge control electrode. The reference numeral 1-28 designates a secondary signal. The reference numeral 1-29 designates a blanking deflector. The reference numeral 1-30 designates a blanking signal generating unit. The reference numeral 1-31 designates a detection signal amplifier. The reference numeral 1-32 designates an A/D converter. The reference numeral 1-39 designates a control unit. The reference numeral 1-41 designates a retarding voltage control unit. Next, a flow of processing for setting the irradiating condition that does not cause a change in the charged state of the wafer surface will be described with reference to FIGS. 13 to 15. A description will be made with reference to FIG. 1, if necessary. First, at step 13-1, the processing is started, and the wafer 1-12 to be inspected is loaded. Next, a layout of the circuit pattern of the wafer 1-12 to be inspected is set, at step 13-2. This step of setting the layout is performed when the wafer is a new product. When product data on the same layout has already been set, automatic retrieval of the layout data can be performed if the set product data is selected. Next, an image of the wafer 1-12 to be inspected is obtained, and alignment is performed at step 13-3. With this arrangement, information on rotation of the wafer 1-12 to be inspected and information on the position of the wafer 1-12 are thereby obtained and fed back to deflection control during electron beam scanning. Beam irradiation is thereby accurately performed onto a region to be inspected, and a magnification at the time of comparison with the image of an adjacent region is thereby corrected. Next, the irradiating condition of the electron beam is set at step 13-4. Assume that an inspection object is a floating wiring pattern. Then, when the beam irradiating condition is set so that the amount of emitted electrons becomes substantially the same as the amount of secondary electrons that will be generated, charging will not vary even if irradiation of the electron beam is continued. For this reason, a voltage to be applied from the power supply for charge control electrode 1-21 to the charge control electrode 1-17 above the wafer is swung, thereby adjusting the amount of the generated secondary electrons that will reach the detector 1-25. When a barrier potential formed by the voltage applied to the charge control electrode 1-17 is higher than the potential of the wafer 1-12 to be inspected, the secondary electrons are actively lifted toward upward. The floating wiring pattern of the wafer 1-12 to be inspected is therefore positively charged. When the voltage to be applied to the charge control electrode 1-17 is reduced so that the barrier potential becomes the same as or lower than the potential of the wafer 1-12, part of the secondary electrons are pulled back to the surface of the wafer 1-12. Then, when the voltage to be applied to the charge control electrode 1-17 is further reduced, the ratio of the secondary electrons pulled back to the surface of the wafer 1-12 is increased. The surface of the wafer 1-12 is thereby negatively charged due to the pulled back electrons. Since a lot of the generated secondary electrons are pulled back to the surface of the wafer 1-12 in this case, the number of the electrons that will reach the detector 1-25 is reduced, so that the image will be darkened. Since the relationship between the voltage to be applied to the charge control electrode and brightness of the image as described above is present, the potential state of the surface of the wafer 1-12 can be known by measuring the number of the secondary electrons that has reached the detector 1-25 or the brightness of the image. FIG. 14 is a graph showing the relationship between the electrode potential of the charge control electrode 1-17 and the brightness of the electron beam image. It can be seen that, as the electrode potential of the charge control electrode 1-17 above the surface of the wafer 1-12 is reduced, the brightness of the image is reduced, as described above. A region with the constant brightness of the image shows the state of positive charging, while a region that is darkened shows the state of negative charging. Accordingly, a point of change in the brightness may be a boundary between the state of the positive charging and the state of the negative charging or the point at which switching between the positive charging and the negative charging is performed and the point which is weakly charged. By setting this point of change as an inspecting condition, the amount of electric charges on the surface of the wafer can be reduced, and stable inspection on the wafer can be performed. In an example shown in FIG. 14, a region in the vicinity of an applied voltage V1 is estimated to be the point of change. The point of change is roughly included in the voltage range of a region enclosed by a broken line in the vicinity of the applied voltage V1. In order to obtain the point of change with a higher accuracy, by finely changing the electrode potential of the charge control electrode 1-17, the electron beam images of the region in the vicinity of the applied voltage V1 enclosed by the broken line are obtained as shown in FIG. 15. Then, correspondences with signals showing the brightness of the image are detected. An optimal irradiating condition can be thereby obtained in a short time, with a high efficiency, and with high accuracy. Assume that an image evaluation value of a positively charged region (or a high voltage region) is set to 100%. The image evaluation value indicates the average brightness of the image and the image evaluation value of 100% is obtained when the image evaluation value is flat. Then, processing for setting the value of the applied voltage that makes the image estimation value to be 90% to an applied voltage V2, for example, is performed. As a procedure of setting the irradiating condition, following processing as shown at step 13-4 in FIG. 13 is performed. 1) The voltage to be applied to the charge control electrode is swung to obtain images at five applied voltages, for example. 2) The image evaluation values of the images are computed. 3) Correspondences between the voltages applied to the charge control electrode and the image evaluation values are displayed. 4) The applied voltage at which the evaluation value starts to decrease is measured. 5) The voltage applied to the charge control electrode in the vicinity of this applied voltage is finely swung to obtain five images at five applied voltages, for example. 6) The image evaluation values of the images are computed. 7) Correspondences between the voltages applied to the charge control electrode and the image evaluation values are displayed. 8) The applied voltage at which the image evaluation value starts to decrease is measured. 9) The voltage V2 to be applied to the charge control electrode is determined. After the irradiating condition that should be set has been determined as described above, a cell and die inspection region (or a wafer inspection region) is set at step 13-5, and the brightness and the contrast of the image in the wafer inspection region are set to be optimal at step 13-6. Then, an image processing condition and a threshold value are set at step 13-7. A test run of the inspection is thereby performed at step 13-8. At the time of the trial inspection, the location being inspected and presence or absence of drift of a focal point are checked at step 13-9. If the drift is not generated at step 13-9 (YES at step 13-9), presence or absence of erroneous detection is checked at step 13-10. Then, if required, the inspection is continuously executed at step 13-11. A recipe, which is the set condition obtained from the processing is stored in a memory or the image and inspection data storage unit 1-44 at step 13-13. Then, steps of the inspection are finished. If the drift is generated, the procedure is returned to the step 13-4 for setting the irradiating condition, and checking of the irradiating condition is performed again. Then, a newly obtained optimal irradiating condition is set. Further, when the erroneous detection is generated at step 13-10, the procedure is returned to the step 13-7 for setting the image processing condition and the threshold. Parameters are thereby changed. Conventionally, there was no method of determining the optimal irradiating condition. Hence, by performing checking after the test run, the irradiating condition was determined. Accordingly, whenever the drift was generated, adjustment is repeated. An enormous time was therefore required for setting the recipe. When the irradiating condition is set and the inspection is performed using the inspection technology according to this embodiment, a change between an image 16-1 in an initial state of the inspection and an image 16-2 in an advanced state of the inspection can be reduced, as shown in FIG. 16. The inspection can be thereby continued with the same sensitivity. By using the inspection technology described so far, it becomes possible to determine and set an optimal inspecting condition easily and with high accuracy. Under the optimal inspection, the stable inspection can be performed even on the wafer to be inspected that is easily subject to the influence of charge, without interruption. As a result, it becomes possible to perform inspection of a defect on the wiring test pattern including the floating structure which has been hitherto difficult to identify the location of a defect therein, with high sensitivity. Further, when setting the optimal inspecting condition, conventionally, the defect detection sensitivity of the inspection and a set time for the inspection were varied according to the skill and the experience of an operator. On contrast therewith, by using the technology according to this embodiment, the optimal inspecting condition can be set in a short time. Accordingly, the time required for the operator to perform the inspection can be saved. A waiting period until switchover to the next manufacturing step is performed is greatly reduced, so that a turnaround time (TAT) for detecting occurrence of a fault can be reduced. As described above, according to the inspection technology in this embodiment, the wiring step of the semiconductor device can be inspected with high sensitivity and with high accuracy. Thus, the contents of a fault in the wiring step, which are important during the manufacturing process of the semiconductor device can be detected early. Further, information on the location and the size of the defect which is the cause of the fault necessary for taking countermeasures against the fault can be obtained substantially at the same time as the inspection. The TAT required until the countermeasures are taken can be thereby reduced, thus resulting in contribution to improvement in the yield and productivity of the semiconductor device. The foregoing description was directed to a specific flow of the inspection, operations of respective units of the inspection apparatus, a flow for determining the condition of the inspection, and the embodiment of the manner of operation for the inspection and for setting the condition of the inspection. The method of the inspection and the inspection apparatus with a plurality of characteristics claimed within the scope of the present invention combined therein can also be employed. Incidentally, in the semiconductor device in this embodiment, an example was described in which the voltage is applied to the charge control electrode disposed above the wafer, thereby adjusting the amount of charges on the wafer. By changing the potential of the wafer and obtaining the electron beam image in the same manner as described above, a proper inspecting condition may be obtained. As described above, according to the inspection technology for the semiconductor device in this embodiment, even when the wafer to be inspected is particularly and easily subject to the influence of charge, the optimal inspecting condition can be set easily and with high accuracy. Under the optimal inspecting condition, the stable inspection can be performed without interruption. As a result, highly sensitive inspection of a defect can be performed on the wiring test pattern which has been hitherto difficult to identify the location of a defect therein. Further, when setting the optimal inspecting condition, conventionally, the sensitivity of the inspection and the set time for the inspection were varied according to the skill and the experience of the operator. On contrast therewith, by using the technology according to this embodiment, the defect detection sensitivity of the inspection and the set time for the inspection can be set in a short time. The present invention can be used as the inspection technology and the inspection apparatus for the semiconductor device. It should be further understood by those skilled in the art that although the foregoing description has been made on embodiments of the invention, the invention is not limited thereto and various changes and modifications may be made without departing from the spirit of the invention and the scope of the appended claims.
	description	This application is a 371 of international application of PCT application serial no. PCT/CN2021/098569, filed on Jun. 7, 2021, which claims the priority benefit of China application no. 202010578765.9, filed on Jun. 23, 2020. The entirety of each of the above mentioned patent applications is hereby incorporated by reference herein and made a part of this specification. The present invention relates to the technical field of nuclear power, in particular to a travelling wave reactor for a space exploration. A travelling wave (fast) reactor is a fast neutron reactor which uses fast neutrons to carry out a chain fission reaction and provide energy. The reactor uses an open fuel cycle strategy, and fuel recycle processing is not needed, and natural uranium or spent fuel of a thermal reactor can be directly used as fuel, and the burning of reactor can persist to a sufficient burn-up depth by one-time loading, such that shutdown for refueling is avoided during a service life. Taking a uranium-plutonium cycle as an example, the basic principle is as follows: a reactor core is divided, in an axial direction (a travelling wave direction), into an ignition region in a small part and a subcritical region (natural uranium or spent fuel of a thermal reactor) in a large part. When the reactor is started up, the ignition region “ignites” and reaches criticality at first, generated fast neutrons will convert 238U in the nearby subcritical region into 239Pu, and then converted 239Pu enables a nearby region to reach the criticality, thus forming a “breed-and-burn wave”. The wave continuously enables natural uranium or spent fuel in front of the wave to generate a breeding reaction, and then a “burn-up” (critical fission) reaction phase is started. In the propagation direction of the wave, local reactivity rises to supercriticality first and then falls to subcriticality, and a critical wave slowly passes through the whole reactor core in the axial direction during the service life of the reactor core. In this process, the travelling wave reactor enters a self-sustaining stage after ignition and start-up, and residual reactivity of the whole reactor remains unchanged in an ideal state during burn-up, so corresponding reactivity control is not needed. Theoretically speaking, for a self-sustaining travelling wave fast reactor with arbitrarily long service life, only the fuel reserve in the travelling wave direction of the reactor core needs to be increased. Nowadays, research on travelling wave reactors is limited to reactor types used on land, and as deep space exploration advances constantly, a travelling wave reactor for a deep space exploration needs to be designed. The objective of the present invention is to overcome the above drawbacks of the prior art and provide a travelling wave reactor for a space exploration. The travelling wave reactor can meet power requirements of the space exploration, and meanwhile avoid a load pressure of an overweight travelling wave reactor on a spacecraft. The objective of the present invention can be realized by the following technical solution: The core of the travelling wave reactor for a space exploration is divided into several modules in the wave propagating direction; a new reactor consists of a starting source module and a plurality of fresh fuel modules sequentially at zero burnup state; all the modules are coaxially assembled in the travelling wave direction using assembling parts, and each module further includes a heat pipe; and during assembly, the heat pipe in each module positioned at a front part sequentially passes through all the modules positioned at a rear portion thereof and extends out of the module at a rear end. The starting source module is used for emitting neutron flow to enable the fresh fuel module nearby to generate a nuclear critical reaction, and the new fuel module enables the nuclear critical reaction to continue to form a critical travelling wave. After a period of time of burn-up, the reactor core of the travelling wave reactor sequentially consists of the starting source module, a spent fuel module, a critical fuel module and the new fuel module in the travelling wave direction. The spent fuel module is generated after the new fuel module is subjected to the critical nuclear reaction, and a certain amount of fissile nuclide is generated after the new fuel module experiences a sufficient amount of nuclear conversion reactions, so as to enter the nuclear criticality state, and in the state, the number of neutrons released in the critical fuel module by means of the nuclear fission reaction exceeds the number of neutrons absorbed thereby, so as to promote nuclear conversion in the new fuel module on one side. Preferably, all the modules in the travelling wave reactor are assembled in space after being transported from a land to the space. Preferably, the starting source module includes a starting source inner layer and a starting source outer layer in a radial direction, the starting source inner layer being provided with a neutron source material, and the starting source outer layer being a neutron shielding layer. Preferably, the new fuel module includes a new fuel inner layer and a new fuel outer layer in a radial direction, the new fuel inner layer being filled with a convertible material, and the new fuel outer layer being a neutron shielding layer. Preferably, uniform sections of all the modules in the travelling wave reactor are in butt joint. Preferably, the assembling parts includes a fastening hasp and a fastening bolt which are arranged on edge sides of two end portions of each module, and each two adjacent modules are detachably assembled by means of the fastening hasp and the fastening bolt. Preferably, each module in the travelling wave reactor further includes a butt joint positioning member for coaxial butt joint during assembly. Preferably, the butt joint positioning member includes a bump and a groove which are coaxially arranged at two ends of each module, and during assembly, the bump and the groove on each two adjacent modules match each other. Preferably, when the travelling wave reactor is used as a power source for the space exploration, a specific application mode is as follows: firstly, a set number of starting source module and new fuel modules of the travelling wave reactor are launched to a preset position in space. Then, the new fuel modules are sequentially and axially connected by means of the assembling parts to form a new fuel module group. Finally, the starting source module is mounted at a head end of the new fuel module group by means of the assembling parts, and the heat pipes extending out of an end portion is connected to a thermoelectric conversion device, then start the travelling wave reactor to burn. Preferably, when the travelling wave reactor operates, spent fuel is continuously accumulated at a rear portion of the travelling wave direction to form the spent fuel module, and on the premise of ensuring a criticality of the reactor core by nuclear physics calculation, the starting source module and part of the spent fuel modules are separated from the travelling wave reactor and discarded. Compared with the prior art, the present invention has the following advantages: (1) According to the present invention, reactor core materials of the travelling wave reactor are designed in a modularized manner, and a length of the reactor core in a travelling wave transmission direction may be changed as required like building blocks such that travelling wave reactors with corresponding lengths may be provided according to features and lengths of space missions, so as to meet the power requirements of the space exploration and meanwhile avoid the load pressure brought by the overweight travelling wave reactor to the spacecraft. (2) The reactor core materials of the present invention are launched in a modularized manner, and assembled in the space, so as to reduce requirements of launching power. (3) According to the present invention, with regard to a specific mission of the space exploration, since after a period of time of operation, spent fuel is continuously accumulated at the rear portion of the travelling wave direction of the travelling wave reactor, on the premise of ensuring the criticality of the reactor core, the starting source module and part of the spent fuel modules may be directly discarded as “deadweights” such that on one hand, a load of the spacecraft may be reduced, and on the other hand, a one-time propulsion may be obtained during discarding, so as to improve power efficiency of the space exploration. The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the following description of the implementations is merely illustrative in nature, and the present invention is not intended to be limited to its application objects or use, and the present invention is not limited to the following implementations. As shown in FIG. 1, a reactor core of a travelling wave reactor for a space exploration is dispersed into several modules in a travelling wave direction; a new reactor is sequentially provided with a starting source module 1 and a plurality of new fuel modules 4 at zero burnup. All the modules are coaxially assembled in the travelling wave direction by means of assembling parts. Uniform sections of all the modules in the travelling wave reactor are in butt joint. Each module further includes a heat pipe 9 for conducting out heat. During assembly, the heat pipe 9 in each module positioned at a front part sequentially passes through all the modules positioned at a rear portion thereof and extends out of the module at a rear end. The heat pipe 9 is a closed metal tube containing a liquid heat conducting substance, these pipes come out of the reactor, and the other end thereof is inserted into a thermoelectric conversion device to supply power to a spacecraft. All the modules in the whole travelling wave reactor are assembled in space after being transported from a land to the space, and the heat pipe 9 has an extraction function, that is, when the module at the front part is separated from the hot reactor, the heat pipe 9 thereon is extracted from all the modules at the rear portion. The starting source module 1 is used for emitting neutron flow to enable the new fuel module 4 nearby to absorb neutrons to cause nuclear conversion reaction, so as to accumulate fissile nuclides to cause nuclear critical reaction. The new fuel module 4 contains a large amount of materials capable of generating fissile nuclides by means of the nuclear conversion reaction, such that the nuclear critical reaction may continue to form a critical travelling wave. In the embodiment, one starting source module 1 is arranged, and ten new fuel modules 4 are arranged. After a period of time of burning, spent fuel is generated, and meanwhile, a fuel module in nuclear criticality is also generated. Therefore, as described in FIG. 2, after a period of time of burn-up, the reactor core of the travelling wave reactor is provided with the starting source module 1, a spent fuel module 2, a critical fuel module 3 and the new fuel module 4 sequentially in the travelling wave direction, that is, the spent fuel module 2 and the critical fuel module 3 are generated after burning. The spent fuel module 2 is generated after the new fuel module 4 is subjected to the critical nuclear reaction, a certain amount of fissile nuclide is generated after nuclides in new fuel absorbing external neutrons to cause a sufficient amount of nuclear conversion reactions, so as to enter the nuclear criticality state, and in the state, the number of neutrons released by the critical fuel module 3 by means of the nuclear fission reaction exceeds then number of neutrons absorbed thereby, so as to promote nuclear conversion in new fuel on one side. In FIG. 2, after the travelling wave reactor in the embodiment is burned for a period of, two spent fuel modules 2 and two critical fuel modules 3 are generated, and six new fuel modules 4 are remained. The starting source module 1, the new fuel module 4, etc. may be set as cylindrical structures, and mainly include common neutron source materials such as Cf or Po—Be coated with stainless steel materials. The new fuel module 4 is mainly composed of a convertible material such as U238 coated with stainless steel. The starting source module 1 and the new fuel module 4 may each be divided into an inner layer and an outer layer in a radial direction. The inner layers are filled with the above effective materials (the inner layer of the starting source module 1 is filled with the neutron source material, and the inner layer of the new fuel module 4 is filled with the convertible material). The outer layer of each module is a neutron shielding layer, such that the neutron flow is mainly transmitted in the axial direction. When a new reactor is started, one side of an outer layer in a radial direction and an outermost end in an axial direction of the starting source are covered with neutron reflecting layers, so as to guide the neutron flow to be injected into the new fuel module 4 in the axial direction. A large number of nuclides in the adjacent new fuel module 4 are continuously converted into fissile nuclides, so as to enter nuclear criticality state, nuclear fission reactions is generated to release a large number of neutrons, so as to continue to convert a large amount of nuclides in the adjacent new fuel module 4 into fissile nuclides, meanwhile, a large amount of fissile nuclides are consumed due to a fission reaction in the new fuel module, such that the new fuel module degrades into the spent fuel module 2, and the adjacent new fuel module 4 enters nuclear criticality state such that it can be seen that the breeding wave (a large number of fissile materials generated by the nuclear conversion reaction) and the critical wave are sequentially transmitted in the axial direction. In this way, the whole travelling wave reactor may continuously provide fission energy, and provide a space propulsion by means of nuclear thermal conversion or nuclear electric conversion. As shown in FIG. 3, the assembling parts includes a fastening hasp 5 and a fastening bolt 6 which are arranged on edge sides of two end portions of each module, and each two adjacent modules are detachably assembled by means of the fastening hasp 5 and the fastening bolt 6, specifically, the fastening bolt 6 is rotated and buckled into the fastening hasp 5 to tightly combine the two adjacent modules. Meanwhile, during butt joint, the heat pipe 9 also has a positioning function, but as each module needs to have an extraction function, the following design is adopted. As shown in FIG. 3, assembly of three modules is taken as a schematic diagram, one heat pipe 9 extends out of a left module to carry out heat generated thereby, the heat pipe passes through the two modules on a right side and then is inserted into the thermoelectric conversion device, such that one heat pipe 9 extends out of a middle module, and besides, the middle module is provided with a perforation for all the modules 9 (not all shown in the figure) on a left side to pass through, so do the modules on the right side. In this way, when each module is separated from the thermal reactor, the heat pipe 9 thereof is extracted together to realize separation. When the travelling wave reactor is used as a power source for the space exploration, a specific application mode is as follows: Firstly, a set number of starting source module 1 and new fuel modules 4 of the travelling wave reactor are launched to a preset position of the space. Then, the new fuel modules 4 are sequentially and axially connected by means of the assembling parts to form a new fuel module group. Finally, the starting source module 1 is mounted at a head end of the new fuel module group by means of the assembling parts, and the heat pipe 9 extending out of an end portion is connected to a thermoelectric conversion device, then start the travelling wave reactor to burn, the heat pipe 9 conducts heat generated by the hot reactor, and the heat is converted into electrical energy by means of the thermoelectric conversion device, so as to supply power to a spacecraft. When the travelling wave reactor operates, spent fuel is continuously accumulated at a rear portion of the travelling wave direction to form the spent fuel module 2, and on the premise of ensuring a criticality of the reactor core by means of nuclear physics calculation, the starting source module 1 and part of the spent fuel modules 2 are separated from the travelling wave reactor and discarded. As shown in FIG. 4, the starting source module and part of the spent fuel modules are discarded in a travelling wave transmission direction from left to right in sequence. When a certain spent fuel module 2 is to be discarded, the fastening hasp 5 in the module adjacent to the right side of the spent fuel module is also opened, such that the module is automatically separated from a travelling wave reactor body. FIG. 4 shows that during discharging for the first time, the starting source module 1 at the head end and one spent fuel module 2 are discarded, at the same time, the heat pipes 9 on the discarded starting source module 1 and the spent fuel module 2 are also discarded away from the thermal reactor, and as the travelling wave reactor continuously operates, the spent fuel module 2 may be continuously discarded from a left end in the figure. The travelling wave reactor of the present invention has the following design points: (1) The reactor core is designed in a building block manner. With regard to the reactor used for a deep space exploration, operation features of the travelling wave reactor may be utilized to increase or decrease a length of a new fuel interval according to features and lengths of space missions. In this design, a reactor core material in the travelling wave direction is designed in a modularized manner such that a length of the reactor core in the travelling wave transmission direction may be changed as required like building blocks. (2) The reactor core materials are launched in a modularized manner, and assembled in the space. In order to meet requirements of critical mass of the reactor and overcome a pressure of an overall launch weight (such as a long-term mission) of the reactor on a single launch mission, the whole reactor core extending in the travelling wave direction (the axial direction) is separated into several modules, then the modules are separately launched to a preset orbit and then are axially connected on a space station or other extraterrestrial bases, and finally, the starting source module 1 is mounted to start the reactor. (3) Spent fuel may be discarded to provide extra propulsion. With regard to a specific mission of the space exploration, since after a period of time of operation, spent fuel is continuously accumulated at the rear portion of the travelling wave direction of the travelling wave reactor, on the premise of ensuring the criticality of the reactor core, part of the spent fuel modules may be directly discarded as a “deadweight” such that on one hand, the load of the spacecraft may be reduced, and on the other hand, the one-time propulsion may be obtained during discarding, so as to improve power efficiency of the space exploration. In this embodiment, the number (10) of the new fuel modules 4 is relatively great at zero burnup, which is suitable for a long-term operation. A structure of the travelling wave reactor for a space exploration in the embodiment is the same as that in Embodiment 1, and a difference is that each module in the travelling wave reactor further includes a butt joint positioning member for coaxial butt joint during assembly. As shown in FIG. 5, the butt joint positioning member includes a bump 7 and a groove 8 which are coaxially arranged at two ends of each module, and during assembly, in addition to the positioning function of the heat pipe 9, the bump 7 and the groove 8 on each two adjacent modules match each other, such that positioning accuracy is higher, and reliability of assembly is improved. FIG. 6 shows a schematic diagram of a short-cycle reactor core structure of the travelling wave reactor for a space exploration in the embodiment. In the core of the travelling wave reactor, one starting source module 1 is arranged, and eight new fuel modules 4 are arranged at zero burnup. The other features are the same as those of Embodiment 1. FIG. 7 is a schematic diagram of a state of the reactor core travelling wave reactor after a period of time of burn-up in the embodiment, two spent fuel modules 2 and two critical fuel modules 3 are arranged, and four new fuel modules 4 are remained. During burning, by discarding part of the spent fuel modules as “deadweights”, on the one hand, the load of the spacecraft may be reduced, and on the other hand, the one-time propulsion may be obtained during discarding, so as to improve power efficiency of the space exploration. The above implementations are merely exemplary, and are not intended to limit the scope of the present invention. These implementations may also be carried out in various other ways, and various omissions, substitutions and changes may be made without departing from the scope of the technical idea of the present invention.
045405450	description	DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 3 through 5, an upper grid 20 and a lower support plate, not shown, are arranged in a reactor core of a reactor pressure vessel and the upper grid 20 is provided with a plurality of through holes through which fuel assembly units, each comprising four fuel assemblies 1, are installed respectively. Each fuel assembly 1 comprises a plurality of fuel rods which are supported by an upper tie plate 3 (FIG. 1) at its upper portion, by a lower tie plate 4 (FIG. 1) at its lower end, and by fuel spacers 5 located between the upper and lower tie plate with suitable spaces. The outer surface of the fuel assembly 1 is entirely surrounded by a channel box 6. An inverted U-shape stationary handle 7 is attached to the upper tie plate 3 along the diagonal line of the top portion thereof and a movable handle 8, which has substantially the same shape as that of the handle 7, is attached thereto so as to be vertically movable, for example, in a manner that legs of the movable handle 8 can be slidably inserted through a pair of upper and lower guide members 7A mounted on the legs of the stationary handle 7 and supported by spring means described hereunder. It will be desirable for the handle 8 to have a horizontal top portion which is slightly bent upwardly at its central portion. The movable handle 8 is urged downwardly by spring means 10, preferably tension coil springs as shown in FIG. 3, which are attached to the legs of the movable handle 8 at their upper ends and to the lower guide members 7 at their lower ends, respectively. When the handle 8 is slidably pulled upwardly by engaging it with a mast hook 25, shown by dotted lines in FIG. 5, the springs 10 extend upwardly to a position where the upper horizontal portion of the handle 8 comes into contact with the upper horizontal portion of the stationary handle 7 and at this position both handles 7 and 8 engage with the mast hook 25. It will be required for the tension spring 10 to have a spring force only sufficient for engaging a projected one end of a hook member, described hereinafter, with a groove 21 provided for the upper grid 20 when the movable handle 8 is lowered, so that the restoring force of the spring 10 at a time when the movable handle 8 is lifted and comes into contact with that of the handle 7 is considered to be significantly smaller in comparison with the entire weight of the fuel assembly 1. Hook members 11 having an arm shape are pivotally attached to the legs of the handle 7 or upper tie plate 3 with pins 12 in a manner to be rotatable thereabout when the handle 8 is moved vertically. The engagement of each hook member 11 with the corresponding leg of the movable handle 8 can be achieved by engaging a projection 9 of an inwardly U-shaped end portion of the leg with a bifurcated upper end portion of the hook member 11 which is also provided with an outwardly projecting lower end portion 14 which is engaged with a groove 21 provided for the upper grid 20, the groove 21 being communicated with an opening 6A provided for the channel box 6 when the movable handle 8 occupies its lower position, and released from the groove 21 when the movable handle 8 is pulled upwardly by the mast hook 25. These states of the hook members 11 are clearly shown in FIGS. 4 and 5. Thus, briefly stated the hook members 11 are rotated about the pins 12 to engage with or disengage from the upper grid 20 in accordance with the vertical movement of the movable handle 8. Since the vertical motion of the movable handle 8 is converted into the rotation of the hook member 11, it will easily be understood that a rack and pinion engagement may be utilized between the handle 8 and the hook member 11 and another combination of suitable members may be used within the scope of this invention. Moreover, with the illustrated embodiment, roller means, not shown, may be provided on either one of the projection 9 or bifurcated member 13 for smoothly engaging the hook member 11. At the time of loading the fuel assembly which is now suspended by the mast hook 25 through the stationary and movable handles 7 and 8, the hook members 11 do not engage with the upper grid 20 but are received within the channel box 6, so that the suspended fuel assembly can be smoothly lowered into the upper grid 20 of the reactor core. When the lower end of the fuel assembly 1 has been settled on the fuel support 23 (FIG. 1), the mast hook 25 is disengaged from the handles 7 and 8 and only the handle 8 is then lowered by the restoring force of the tension coil springs 10. This downward movement of the handle 8 is converted into the rotation of the hook members 11 about the pins 12 through the engagement of the projections 9 with the bifurcated portions 13 of the hook members 11 whereby the lower end projection 14 of the hook member 11 would project into the groove 21 of the upper grid 20 through the opening 6A of the channel box 6. When it is required to remove the fuel assembly 1 from the upper grid 20 of the reactor core, the mast hook 25 is first engaged with the horizontal top portion of the movable handle 8 to pull the same upwardly. The hook members 11 are then rotated about the respective pins 12 to disengage the lower ends 14 of the hook members 11 from the grooves 21 of the upper grid 20. Under such condition, the handle 8 can move upwardly together with the handle 7 to smoothly take out the fuel assembly of the reactor core. As is apparent from the foregoing description, with an operative connection or engagement with the movable handle 8, tension coil spring 10, hook members 11 and upper grid 20 shown in the preferred embodiment of this invention, when the movable handle 8 moves upwardly or downwardly, the hook members 11 are caused to disengage from or engage with the grooves 21 of the upper grid 20 of the reactor core. In a normal operating condition of the BWR, in which the fuel assemblies are loaded into the reactor core, the movable handle is caused to assume its lowered position by the spring means, and the hook members are firmly engaged with the upper grid, whereby the vertical as well as horizontal vibrations and movements of the fuel assemblies can be safely prevented even when an emergency such as an earthquake occurs. The removal of the fuel assemblies from the reactor core, for example, in case of unloading the assemblies can be achieved only by upwardly pulling the movable handle with the mast hook. At this time, the hook members are caused to disengage smoothly from the upper grid of the reactor core and the fuel assembly is then completely pulled away therefrom by further lifting upwardly the movable handle together with the stationary handle with the mast hook. The device according to this invention has a simple construction, so that it can easily be attached to conventional fuel assembly supporting means only by slightly changing the construction of the conventional device of this kind and the device is durable for long use in water having high temperature in the reactor core with high precision and reliability. FIGS. 6 and 7 show another embodiment of this invention, in which the movable handle 8 is provided with inwardly projecting lower end portions, which are connected through links 31 to upper portions of generally Z-shaped hook members 11, respectively. With this embodiment, when the movable handle 8 is pulled upwardly and suspended together with the stationary handle 7 by the mast hook 25, the hook members 11 are rotated about the pins 12 in directions in which the lower end portions 14 of the hook members disengage from the grooves 21 of the upper grid 20 as shown in FIG. 7. On the other hand, when the fuel assembly is loaded into the reactor core and settled on the supporting member, the mast hook 25 disengages the handles 7 and 8 and the handle 8 is then slidably lowered by the action of the tension coil springs 10. The lowering of the handle 8 renders the hook members 11 to rotate about the pins 12 in directions in which the lower end portions 14 of the respective hook members 11 engage with the corresponding grooves 21 of the upper grid 20 thereby to firmly lock the fuel assembly in position. According to a device of this invention for firmly supporting a fuel assembly unit in a reactor core of a BWR, the fuel assembly unit loaded in the reactor core can be firmly secured thereto so as not to move or vibrate upwardly, so that any accidental upward movement of the fuel assembly can be prevented thereby to safely insert the control rod to promptly control the reactor core upon occurrence of an emergency. Moreover, when it is required to unload the fuel assembly unit, it can be readily removed by using no additional specific means. The device has a simple construction which can be applied to a conventional device only by slightly changing the design thereof and is durable for long time use with high precision and reliability.
	claims	1. An X-ray exposure apparatus comprising: a point X-ray source for generating pulsed X-rays, which are emitted radially from said point X-ray source; first to nth exposure-means, each of which is disposed in a position facing said point X-ray source to receive the pulsed X-rays in an approximately perpendicular direction, to each of the first to nth exposure means, wherein said exposure means project patterns of first to nth masks onto respective ones of first to nth substrates that are to be exposed. 2. The apparatus according to claim 1 , further comprising: claim 1 first to nth, where a represents an integer of at least two, collimators for varying at least one of angle and intensity of X-rays generated by said X-ray source. 3. The apparatus according to claim 1 , further comprising: claim 1 first to nth shutters situated between said X-ray source and respective ones of the masks and having at least one shielding member for shielding X-rays that irradiate the masks; first to nth shutter drive units for driving respective ones of said shutters; and a shutter controller for controlling each of said shutters. 4. The apparatus according to claim 3 , wherein said shutter drive unit controls said first to nth shutters depending upon the state of said X-ray source and at least one state among the states of said first to nth exposure means. claim 3 5. The apparatus according to claim 1 , wherein timing of X-ray emission from said X-ray source is controlled by an X-ray emission trigger signal, claim 1 said apparatus further comprising an X-ray emission trigger generating unit for generating the X-ray emission trigger signal depending upon the state of said X-ray source and at least one state among the states of said first to nth exposure means. 6. The apparatus according to claim 1 , wherein intensity of X-rays from said X-ray source is controlled by an X-ray intensity control signal, claim 1 said apparatus further comprising an X-ray intensity control signal generator for generating an X-ray intensity signal control signal depending upon the state of said X-ray source and at least one state among the states of said first to nth exposure means. 7. The apparatus according to claim 6 , further comprising a total control unit, which receives information for specifying the internal status of a point source X-ray source unit having said point-source X-ray source, as a status signal from said point-source X-ray source unit, for exercising total control which combine said shutter control unit and a plurality of controllers that control the exposure states of each of said exposure means based upon measurement values from a plurality of sensors that measure the X-ray intensities of respective ones-of said exposure means, claim 6 wherein said total control unit sends said X-ray emission trigger signal generating unit a trigger generation command and sends said X-ray intensity control signal generator at least one of an X-ray intensity value and an X-ray intensity command. 8. The apparatus according to claim 7 , wherein said total control unit has means for controlling exposure timing of each exposure means in accordance with a prescribed objective, said exposure timing being tunable within a range of set values that have been set in said total control unit. claim 7 9. The apparatus according to claim 1 , further comprising first to nth moving means for moving at least one of respective ones of said masks and said substrates. claim 1 10. The apparatus according to claim 1 , wherein an optical-axis center of each collimator is configured radially with respect to the X-ray source. claim 1 11. The apparatus according to claim 1 , further comprising: claim 1 an interface for being connected to a network; a computer for running network software for communicating maintenance information for said exposure apparatus by data communication via the network; and a display for displaying the maintenance information for said exposure apparatus communicated by the network software run by said computer. 12. The apparatus according to claim 11 , wherein said network software provides said display with a user interface for accessing a maintenance database, which is connected to an external network of a plant at which said X-ray exposure apparatus has been installed, and which is supplied by a vendor or user of the X-ray exposure apparatus, thereby making it possible to obtain information from the database via said external network. claim 11 13. A method of manufacturing a semiconductor device comprising the steps of: placing a plurality of semiconductor manufacturing apparatus, inclusive of an X-ray exposure apparatus, in a plant for manufacturing semiconductor devices; and manufacturing a semiconductor device using the plurality of manufacturing apparatus, the X-ray exposure apparatus including: (i) a point X-ray source for generating pulsed X-rays, which at emitted radially from the X-ray source; and (ii) first to nth exposure means, each of which is disposed in a position facing said point X-ray source to receive the pulsed X-rays in an approximately perpendicular direction to each of the first to nth exposure means, wherein the exposure means project patterns of first to nth masks onto respective ones of first to nth substrates that are to be exposed. 14. The method according to claim 13 , further comprising: claim 13 interconnecting the plurality of semiconductor manufacturing apparatuses by a local-area network; connecting the local-area network and an external network outside the plant; acquiring information relating to the exposure apparatus from a database on the external network utilizing the local-area network and the external network; and controlling the exposure apparatus based upon the information acquired. 15. The method according to claim 14 , wherein maintenance information for the manufacturing apparatus is obtained by accessing, by data communication via the external network a database provided by a vendor or user of the exposure apparatus, or production management is performed by data communication with a semiconductor manufacturing plant other than the first-mentioned semiconductor manufacturing plant via the external network. claim 14 16. A semiconductor manufacturing plant, comprising: a plurality of semiconductor manufacturing apparatus inclusive of an exposure apparatus; a local-area network for interconnecting said plurality of semiconductor manufacturing apparatus; and a gateway for connecting said local-area network and an external network outside said plant, whereby information relating to at least one of said plurality of semiconductor manufacturing apparatus can be communicated by data communication, said X-ray exposure apparatus including: (i) a point X-ray source for generating pulsed X-rays, which are emitted radially from said point X-ray source; and (ii) first to nth exposure means, each of which is disposed in a position facing said point X-ray source to receive the pulsed X-rays in an approximately perpendicular direction, to each of the first to nth exposure means, wherein said exposure means project patterns of first to nth masks onto respective ones of first to nth substrates that are to be exposed. 17. A method of maintaining an X-ray exposure apparatus installed in a semiconductor manufacturing plant, said method comprising the steps of: providing a maintenance database, which is connected to an external network of the semiconductor manufacturing plant, by a vendor or user of the X-ray exposure apparatus; connecting the X-ray exposure apparatus to a local-area network within the semiconductor manufacturing plant; and maintaining the X-ray exposure apparatus, based upon information that is stored in the maintenance database, utilising the external network and the local-area network, the X-ray exposure apparatus including: (i) a point X-ray source for generating pulsed X-rays, which are emitted radially from said point X-ray source; and (ii) first to nth exposure means, each of which is disposed in a position facing said point X-ray source and to receive the X-rays in an approximately perpendicular direction, to each of the first to nth exposure means, wherein said exposure means project patterns of first to nth masks onto respective ones of first to nth substrates that are to be exposed.
051820510	abstract	There is provided radioactive particles having a ceramic matrix and an element which can be bombarded with neutrons to produce a gamma ray-emitting isotope. The particles are manufactured by mixing the ceramic components and the element, forming particles, sintering the particles, and the particles are subsequently made radioactive by bombardment with neutrons. Particles injected into wells or flow apparatus are traced by adding the radioactive particles and detecting the radioactive particles with gamma ray-sensitive instruments. Particles containing different elements are detected by spectral analysis of gamma rays.
	claims	1. A method of manufacturing mirror shells of a nested shells grazing incidence mirror, in particular for EUV radiation and/or X-rays, the method at least comprising the steps ofproviding and machining a blank of a bulk material to form a mirror body of the shell, wherein said mirror body is formed to have edges which are knife edge shapedintegrating and/or attaching mechanical structures in and/or to the mirror body during and/or after said step of machining the blank, andforming an optical surface on the mirror body including said mechanical structures by diamond turning. 2. The method according to claim 1, wherein said step of forming the optical surface includes the steps ofcoating the mirror body at least in a region in which said optical surface is formed with a layer of a second material, said second material being selected to allow the formation of the optical surface from said second material by diamond turning, anddiamond turning said layer of the second material. 3. The method according to claim 1, wherein said step of integrating and/or attaching mechanical structures includes integrating and/or attaching cooling channels and/or mounting elements in and/or to the mirror body. 4. The method according to claim 1, wherein said machining of the blank to form the mirror body comprises at least a milling process. 5. The method according to claim 1, wherein said attaching of mechanical structures to the mirror body comprises at least one of welding and brazing and screwing said structures to the mirror body. 6. The method according to claim 1, wherein said mirror body is formed to have a thickness increasing from both edges of the mirror body to form at least one thicker portion in between. 7. The method according to claim 1, wherein said mirror body is formed to have a thickness of ≧5 mm at a thickness maximum of said at least one thicker portion. 8. The method according to claim 1, wherein the optical surface is additionally polished. 9. The method according to claim 1, wherein the optical surface is additionally coated by an appropriate material increasing the reflectivity and/or the mechanical and/or chemical stability of the optical surface.
	claims	1. A method, comprising:operating a conversion cell to generate electric charge from nuclear radiation;charging a number of charge storage devices electrically coupled in series with the electric charge generated by the conversion cell;changing an electrical configuration of the charge storage devices to discharge electricity while parallel to one another after the charging; andproviding the electricity to a receiving device from the charge storage devices during the discharging. 2. The method of claim 1, wherein the receiving device includes a transformer. 3. The method of claim 1, wherein the nuclear radiation is provided in the form of a beta emission. 4. The method of claim 3, wherein the conversion cell includes 90Sr to provide the beta emission. 5. The method of claim 4, which includes providing the 90Sr in the form of 90strontium titanate. 6. The method of claim 1, wherein the charge storage devices are each a capacitor. 7. The method of claim 6, wherein the charge storage devices are coupled together from one to the next by two spark gaps. 8. The method of claim 7, wherein each of the storage devices corresponds to a different one of at least 100 repeating circuitry stages. 9. An apparatus, comprising:one or more radioisotopic conversion cells to generate electric charge;circuitry with an input to receive the electric charge from the one or more radioisotopic conversion cells and an output to provide electricity, the circuitry including a number of charge storage devices electrically coupled together in series in a first configuration to charge the storage devices with the electric charge from the one or more radioisotopic conversion cells, the circuitry being structured to be reconfigurable to electrically couple the charge storage devices together in parallel in a second configuration to discharge the electricity through the output; andwherein the circuitry includes a number of switching devices responsive to a threshold voltage to change between the first configuration and the second configuration. 10. The apparatus of claim 9, wherein the charge storage devices are each a capacitor and the switching devices are each a spark gap. 11. The apparatus of claim 10, wherein the charge storage devices and the switching devices are arranged as a number of repeating circuitry stages. 12. The apparatus of claim 11, wherein the stages number 100 or more. 13. The apparatus of claim 11, wherein the stages number at least 1000. 14. The apparatus of claim 9, wherein at least one of the radioisotopic conversion cells includes a beta emitter. 15. The apparatus of claim 14, wherein the beta emitter includes 90Sr. 16. A method, comprising:generating electric charge;providing the electric charge to an input of step-down circuitry that includes a number of charge storage devices and a number of switching devices;operating the circuitry in a charging configuration to receive the electric charge, the charging configuration including the switching devices in a first electrical connectivity state to connect the charge storage devices in series; andproviding electricity through an output of the circuitry by operating the circuitry in a discharging configuration, the discharging configuration including the switching devices in a second electrical connectivity state opposite the first state to connect the charge storage devices in parallel. 17. The method of claim 16, wherein the switching devices each include a spark gap. 18. The method of claim 16, wherein the charge storage devices each include a capacitor. 19. The method of claim 16, wherein the switching devices each include a spark gap and the charge storage devices each include a capacitor. 20. The method of claim 19, wherein the switching devices and the charge storage device are arranged in several repeating stages. 21. The method of claim 20, wherein the stages number 100 or more. 22. The method of claim 20, wherein the stages number at least 1000. 23. The method of claim 16, wherein the generating of the electric charge is performed by with one or more radioisotopic conversion cells. 24. The method of claim 23, wherein at least one of the radioisotopic conversion cells includes a beta emitter. 25. The method of claim 24, wherein the beta emitter includes 90Sr.
	summary
043538630	description	In the various figures, the same reference numerals pertain to similar components. The method for localizing according to the invention, a leaking rod in a nuclear fuel assembly generally lies in measuring for each rod in said assembly, the radio-activity, notably the .gamma.-activity, from at least two discrete rod rows in said assembly, in which rows lies said rod, and localizing a possible leaking rod by sensing a varying of said radio-activity in the tested rows where said rod is located, relative to the radio-activity in an identical row of non-leaking rods. In a particular embodiment of the invention, use may advantageously be made of the change in the ratio between two or more radio-active products (fission products, activating products, or tracers). More particularly the radio-activity of the gaseous fission products, activating products, or radio-active tracers accumulated inside the rod plenum(s) is measured, said rods being arranged either inside a desactivating tank containing a cooling medium (water, sodium, etc), or inside a cased cell. FIGS. 1 to 5 show a particular embodiment of said method. FIG. 1 shows diagrammatically an assembly 6 from five rows A, B, C, D and E of rods containing a fissionable material 7 topped by a plenum 8 inside which are collected fission products which are released by the fissionable material during the operation of a nuclear reactor. Said rods are assembled into clusters according to a regular array with a square geometry, the assembly means however have not been shown in the drawings. Among the fission products accumulated inside the plenum, some products are radio-active and generate .gamma.-radiations. Such radiations with high energy, for example larger than 500 keV, easily pass through the structural materials of the assembly at the level of plenums 8. A .gamma.-radiation sensor 9 suitably protected from the surrounding radiations, is arranged behind a collimator 10 with such a size that only the plenums from a single rod row at a time can lie wihtin the viewing field 11 of sensor 9. Said sensing or viewing field 11 has a pyramidal shape mostly spread along the rod axis as clearly shown in FIGS. 1 to 3. Consequently the sensitivity loss in the measuring of the .gamma.-radiations due to the spacing of some rods, is at least partly balanced by such pyramidal shape of the radiation beam captured by the sensor and forming said viewing area 11. Indeed the more some particular rod is spaced away, the larger is the plenum cross-section area lying inside the viewing area 11. Advantageously, the solid angle from the collimator is so selected as to approximately balance the losses by .gamma.-absorption. It would be possible in this respect to adjust the size of slot 12 from collimator 10 along the rod axis. As regards the width of said slot 12, said width is enforced by the activity to be measured and the statistical accuracy. Said width will preferably be substantially smaller than the rod outside diameter to eliminate edge effects such as rod sag, centering of a spring not shown, etc. The .gamma.-radiation sensor 9 comprises for instance a crystal from NaI, Ge(Li), intrinsic Ge, Cd.Te, HgI.sub.2, . . . . Said sensor is connected to a meter 12 which is for example comprised of a recording device for the total activity, or a device for discriminating .gamma.-radiations with energies corresponding to well-characterized fission products, for instance by means of a monochannel device, a multi-channel device, etc. The selection of the measuring method is essentially dependent on the actual working conditions such as the irradiating time, the cooling time, etc. FIGS. 1 to 3 show an actual example of localizing a leaking rod. Said method comprises measuring discretely and succeedingly the .gamma.-activity from rows 1 to 5 in assembly 6 extending along the direction of arrow 14 by subjecting for instance said assembly to a translating along the direction shown by arrows 15 in such a way that plenums 8 from the rods in each such rows 1 to 5 pass through the viewing area 11 from collimator 10. Thereafter, said rod assembly 6 is rotated over a 90.degree.-angle about an axis in parallel relationship with the rods as shown by arrow 16 in FIG. 3, in such a way that the rods lie in that position relative to collimator 10 which is shown in FIG. 3. In a similar way, the .gamma.-radiation from each row A to E extending in the direction of arrow 14 is measured by subjecting rod assembly 6 to a translating in the direction of arrows 15 relative to collimator 10. Said translating may be a continuous or stepwise motion. In the case of a continuous translation the measuring of .gamma.-activity may be plotted in a diagram as shown in FIG. 4. The .gamma.-activity is plotted in ordinates, while the motion of said rod assembly relative to collimator 10 is plotted as abcissae. For clearness' sake, the markings of rows 1 to 5 and A to E have been shown along the abcissa axis. Diagram 18 shows the measuring as performed according to FIG. 2, while diagram 19 shows the measuring as performed according to FIG. 3. When assuming for example that said assembly comprises a single leaking rod in position B4, the .gamma.-activities from rows 4 and B which contain said rod, will show a change in the .gamma.-activity which is for example, as shown in FIG. 4, a lowering of said .gamma.-activity. Moreover it is also possible by computing, to ascertain a varying of the ratio relative to one or more radio-active products. The .gamma.-activity measurings performed in the case of a stepwise translating have been shown in the diagram from FIG. 5 which also enables to localize directly the leaking rod B4. In the case of a stepwise translating, the spacing between two succeeding steps should be substantially equal to the spacing between the axial planes of two succeeding rod rows in said assembly. In the case of a translating and rotating of a rod assembly 6, the sensor may be fixed and in this case, the collimator can be provided in wall 20 of the storage or desactivating tank, or of the cased cell which contains said assembly at the level of rod plenums 8. Said wall then comprises essentially the .gamma.-protection for sensor 9. However in the case where for instance said collimator could not be provided in the wall for practical considerations, in a variation of the method for localizing a leaking rod according to the invention, it would be possible to provide for the translating of that unit formed by collimator 10, sensor 9 and a specific protection thereof against the surrounding radiations. In such a case said unit may for instance cooperate with a mechanism not shown in the figures for translating said unit inside the desactivating or storage tank, or inside the cased cell, for example along the inner surface of the wall 20 thereof. It is thus required in the case of a square array as shown in FIGS. 2 and 3, that said unit may perform two translation motions at right angle to one another along a substantially horizontal direction on the outer side from said rod assembly. Said unit might even be immersed into the cooling medium which is contained inside said tank. The translating of the assembly might however be combined with the translating of the sensor-collimator unit. In such an embodiment the movement of the rod assembly might for example be limited to a simple rotating about an axis in parallel relationship with the rods and the translating of a sensor-collimator unit might be limited to a single direction. In another embodiment, it would be possible to provide a co-ordinated rotating of the assembly and the sensor-collimator unit. Should the rod array have a triangular geometry said rotating of the assembly might be limited to 60.degree. instead of 90.degree., while in the case of a fixed assembly, the angle formed between both translations of the movable sensor-collimator unit should also be 60.degree.. For large-volume assemblies, the share of one rod in the activity of a row is progressively lowered together with the increasing spacing due to the .gamma.-absorption in the structural materials and possibly in the cooling medium. The measuring along four sides for an assembly with square geometry or along six sides for an assembly with triangular geometry allows to confirm the results obtained over two sides, as a rod far away from the one side is close relative to the opposite side. On the other hand, it may be advantageous to perform the measuring over rows in parallel relationship with the diagonals for an assembly with square geometry. However as already mentioned above, the sensitivity loss due to the spacing away of a specific rod can be balanced partly at least by means of the pyramid-shaped viewing field for the collimator. When the .gamma.-absorption in the cooling medium results in too much lowering of the share from the last rods, the sensitivity lowering due to such absorption might be removed by discharging temporarily the cooling medium from the area of those rods to be subjected to radio-activity measuring, that is from the plenums 8. Moreover when the leaking of gaseous fission products from the leaking rod is too small for the localizing to be unquestionable, it would be possible to provide heating of the assembly when measuring said activity or between two activity measurings, to cause a stronger leak which is thus easier to localize. It is further to be noted that the example of localizing as shown diagrammatically in FIGS. 4 and 5 assumes a simple assembly the rods of which are spent uniformly. Actually however, said assemblies may contain empty rods such as RCC control rods, a stacked implementing, etc., which form irregularities at the start. Moreover the rods are not generally spent uniformly, which does of course contribute to an unequal distributing of the activities. For a given assembly type and reactor, there is but little difference from one assembly to another, in such a way that the results may be related to a typical assembly, which is not leaking, to remove the action of said irregularities. It is also possible to minimize the influence of said irregularities or the influence of a position uncertainty, by referring the measured activity to a fission or activating product which is not influenced by the leak. As already mentioned above, the invention further relates to an equipment for localizing a leaking rod in a nuclear fuel assembly. There already results from the above description relating to the method for localizing such a rod that such equipment does comprise an enclosure (storage or desactivating tank, or cased cell) which contains partly at least a rod assembly, and at least one .gamma.-radiation sensor which is arranged behind a collimator with such a size that only the rod plenums lie within the sensing or viewing area of the sensor. FIG. 6 shows a particular embodiment of a part from such an equipment. Said embodiment comprises a cylinder 21 which can be arranged above rod assembly 6 and dipped partly at least in the cooling medium 22 inside the desactivating or storage tank, part of the .gamma.-protection being shown where collimator 10 and sensor 9 are provided. Said cylinder is connected through the top thereof, to a pressurized gas source not shown, by means of a line 23, to allow forcing the cooling medium underneath said cylinder to a level lower than said viewing or sensing area 11 to lower the .gamma.-absorption. This would enable a better sensing of leaking rods the fission product loss of which is relatively small. Moreover with a greater lowering of the cooling medium level inside the cylinder, there would be obtained a better sensing of leaking rods the fission product loss of which is relatively small. The temporary absence of cooling medium at the level of the fissionable material would make easier the .gamma.-heating inside the assembly as well as the release of fission products from said leaking rods. In a particular embodiment of the equipment inside a cased cell, the same result could be obtained by heating said assembly. The temporary closure of a lower valve 24 and depressurizing of the cylinder might further increase the release efficiency of the fission products. It must be understood that the invention is in no way limited to the above embodiments and that many changes may be brought therein without departing from the scope of the invention as defined by the appended claims. For instance it would be possible to provide a plurality of sensors for one and the same rod assembly and even one sensor per row the activity of which is to be measured. In such a case, both the sensors and the rods might remain fixed. According to the invention, said embodiment with a plurality of sensors might be included in the above-mentioned sweating equipment. Moreover, it must be understood that the invention is not limited to the top plenum given as example hereinbefore, but may apply to those various plenums the assembly to be tested might comprise, whatever the level thereof. As already mentioned above, in some cases it is possible to measure the radio-activity from tracers arranged inside the rods when manufacturing same, said tracers either being originally radio-active notably for manufacture control, or being activated by neutron irradiating. Advantageously the rods can be taken-apart inside the assemblies to allow replacing easily the leaking rods.
	description	This application is a continuation of, and claims priority under 35 U.S.C. § 120 to, U.S. patent application Ser. No. 15/997,819, filed on Jun. 5, 2018, and entitled “STORING HAZARDOUS MATERIAL IN A SUBTERRANEAN FORMATION,” which in turn claims priority under 35 U.S.C. § 119 to U.S. Provisional Patent Application Ser. No. 62/515,050, filed on Jun. 5, 2017, and entitled “STORING HAZARDOUS MATERIAL IN A SUBTERRANEAN FORMATION.” The entire contents of the previous applications are incorporated by reference herein. This disclosure relates to storing hazardous material in a subterranean formation and, more particularly, storing spent nuclear fuel in a subterranean formation. Hazardous waste is often placed in long-term, permanent, or semi-permanent storage so as to prevent health issues among a population living near the stored waste. Such hazardous waste storage is often challenging, for example, in terms of storage location identification and surety of containment. For instance, the safe storage of nuclear waste (e.g., spent nuclear fuel, whether from commercial power reactors, test reactors, or even high-grade military waste) is considered to be one of the outstanding challenges of energy technology. Safe storage of the long-lived radioactive waste is a major impediment to the adoption of nuclear power in the United States and around the world. Conventional waste storage methods have emphasized the use of tunnels, and is exemplified by the design of the Yucca Mountain storage facility. Other techniques include boreholes, including vertical boreholes, drilled into crystalline basement rock. Other conventional techniques include forming a tunnel with boreholes emanating from the walls of the tunnel in shallow formations to allow human access. In a general implementation, a hazardous material storage repository includes a drillhole extending into the Earth and including an entry at least proximate a terranean surface, the drillhole including a substantially vertical drillhole portion, a transition drillhole portion coupled to the substantially vertical drillhole portion, and a hazardous material storage drillhole portion coupled to the transition drillhole portion, at least one of the transition drillhole portion or the hazardous material storage drillhole portion including an isolation drillhole portion that is directed vertically toward the terranean surface and away from an intersection between the substantially vertical drillhole portion and the transition drillhole portion; a storage canister positioned in the hazardous material storage drillhole portion, the storage canister sized to fit from the drillhole entry through the substantially vertical drillhole portion, the transition drillhole portion, and into the hazardous material storage drillhole portion of the drillhole, the storage canister including an inner cavity sized enclose hazardous material; and a seal positioned in the drillhole, the seal isolating the hazardous material storage drillhole portion of the drillhole from the entry of the drillhole. In an aspect combinable with the general implementation, the isolation drillhole portion includes a vertically inclined drillhole portion that includes a proximate end coupled to the transition drillhole portion at a first depth and a distal end opposite the proximate end at a second depth shallower than the first depth. In another aspect combinable with any of the previous aspects, the vertically inclined drillhole portion includes the hazardous material storage drillhole portion. In another aspect combinable with any of the previous aspects, an inclination angle of the vertically inclined drillhole portion is determined based at least in part on a distance associated with a disturbed zone of a geologic formation that surrounds the vertically inclined drillhole portion and a length of a distance tangent to a lowest portion of the storage canister and the substantially vertical drillhole portion. In another aspect combinable with any of the previous aspects, the distance associated with the disturbed zone of the geologic formation includes a distance between an outer circumference of the disturbed zone and a radial centerline of the vertically inclined drillhole portion. In another aspect combinable with any of the previous aspects, the inclination angle is about 3 degrees. In another aspect combinable with any of the previous aspects, the isolation drillhole portion includes a J-section drillhole portion coupled between the substantially vertical drillhole portion and the hazardous material storage drillhole portion. In another aspect combinable with any of the previous aspects, the J-section drillhole portion includes the transition drillhole portion. In another aspect combinable with any of the previous aspects, the hazardous material storage drillhole portion includes at least one of a substantially horizontal drillhole portion or a vertically inclined drillhole portion. In another aspect combinable with any of the previous aspects, the isolation drillhole portion includes a vertically undulating drillhole portion coupled to the transition drillhole portion. In another aspect combinable with any of the previous aspects, the transition drillhole portion includes a curved drillhole portion between the substantially vertical drillhole portion and the vertically undulating drillhole portion. In another aspect combinable with any of the previous aspects, the hazardous material storage drillhole portion is located within or below a barrier layer that includes at least one of a shale formation layer, a salt formation layer, or other impermeable formation layer. In another aspect combinable with any of the previous aspects, the hazardous material storage drillhole portion is vertically isolated, by the barrier layer, from a subterranean zone that includes mobile water. In another aspect combinable with any of the previous aspects, the hazardous material storage drillhole portion is formed below the barrier layer and is vertically isolated from the subterranean zone that includes mobile water by the barrier layer. In another aspect combinable with any of the previous aspects, the hazardous material storage drillhole portion is formed within the barrier layer, and is vertically isolated from the subterranean zone that includes mobile water by at least a portion of the barrier layer. In another aspect combinable with any of the previous aspects, the barrier layer includes a permeability of less than about 0.01 millidarcys. In another aspect combinable with any of the previous aspects, the barrier layer includes a brittleness of less than about 10 MPa, where brittleness includes a ratio of compressive stress of the barrier layer to tensile strength of the barrier layer. In another aspect combinable with any of the previous aspects, the barrier layer includes a thickness proximate the hazardous material storage drillhole portion of at least about 100 feet. In another aspect combinable with any of the previous aspects, the barrier layer includes a thickness proximate the hazardous material storage drillhole portion that inhibits diffusion of the hazardous material that escapes the storage canister through the barrier layer for an amount of time that is based on a half-life of the hazardous material. In another aspect combinable with any of the previous aspects, the barrier layer includes about 20 to 30% weight by volume of clay or organic matter. In another aspect combinable with any of the previous aspects, the barrier layer includes an impermeable layer. In another aspect combinable with any of the previous aspects, the barrier layer includes a leakage barrier defined by a time constant for leakage of the hazardous material of 10,000 years or more. In another aspect combinable with any of the previous aspects, the barrier layer includes a hydrocarbon or carbon dioxide bearing formation. In another aspect combinable with any of the previous aspects, the hazardous material includes spent nuclear fuel. Another aspect combinable with any of the previous aspects further includes at least one casing assembly that extends from at or proximate the terranean surface, through the drillhole, and into the hazardous material storage drillhole portion. In another aspect combinable with any of the previous aspects, the storage canister includes a connecting portion configured to couple to at least one of a downhole tool string or another storage canister. In another aspect combinable with any of the previous aspects, the isolation drillhole portion includes a spiral drillhole. In another aspect combinable with any of the previous aspects, the isolation drillhole portion has a specified geometry independent of a stress state of a rock formation into which the isolation drillhole portion is formed. In another general implementation, a method for storing hazardous material includes moving a storage canister through an entry of a drillhole that extends into a terranean surface, the entry at least proximate the terranean surface, the storage canister including an inner cavity sized enclose hazardous material; moving the storage canister through the drillhole that includes a substantially vertical drillhole portion, a transition drillhole portion coupled to the substantially vertical drillhole portion, and a hazardous material storage drillhole portion coupled to the transition drillhole portion, at least one of the transition drillhole portion or the hazardous material storage drillhole portion including an isolation drillhole portion that is directed vertically toward the terranean surface and away from an intersection between the substantially vertical drillhole portion and the transition drillhole portion; moving the storage canister into the hazardous material storage drillhole portion; and forming a seal in the drillhole that isolates the storage portion of the drillhole from the entry of the drillhole. In an aspect combinable with the general implementation, the isolation drillhole portion includes a vertically inclined drillhole portion that includes a proximate end coupled to the transition drillhole portion at a first depth and a distal end opposite the proximate end at a second depth shallower than the first depth. In another aspect combinable with any of the previous aspects, the vertically inclined drillhole portion includes the hazardous material storage drillhole portion. In another aspect combinable with any of the previous aspects, an inclination angle of the vertically inclined drillhole portion is determined based at least in part on a distance associated with a disturbed zone of a geologic formation that surrounds the vertically inclined drillhole portion and a length of a distance tangent to a lowest portion of the storage canister and the substantially vertical drillhole portion. In another aspect combinable with any of the previous aspects, the distance associated with the disturbed zone of the geologic formation includes a distance between an outer circumference of the disturbed zone and a radial centerline of the vertically inclined drillhole portion. In another aspect combinable with any of the previous aspects, the inclination angle is about 3 degrees. In another aspect combinable with any of the previous aspects, the isolation drillhole portion includes a J-section drillhole portion coupled between the substantially vertical drillhole portion and the hazardous material storage drillhole portion. In another aspect combinable with any of the previous aspects, the J-section drillhole portion includes the transition drillhole portion. In another aspect combinable with any of the previous aspects, the hazardous material storage drillhole portion includes at least one of a substantially horizontal drillhole portion or a vertically inclined drillhole portion. In another aspect combinable with any of the previous aspects, the isolation drillhole portion includes a vertically undulating drillhole portion coupled to the transition drillhole portion. In another aspect combinable with any of the previous aspects, the transition drillhole portion includes a curved drillhole portion between the substantially vertical drillhole portion and the vertically undulating drillhole portion. In another aspect combinable with any of the previous aspects, the hazardous material storage drillhole portion is located within or below a barrier layer that includes at least one of a shale formation layer, a salt formation layer, or other impermeable formation layer. In another aspect combinable with any of the previous aspects, the hazardous material storage drillhole portion is vertically isolated, by the barrier layer, from a subterranean zone that includes mobile water. In another aspect combinable with any of the previous aspects, the hazardous material storage drillhole portion is formed below the barrier layer and is vertically isolated from the subterranean zone that includes mobile water by the barrier layer. In another aspect combinable with any of the previous aspects, the hazardous material storage drillhole portion is formed within the barrier layer, and is vertically isolated from the subterranean zone that includes mobile water by at least a portion of the barrier layer. In another aspect combinable with any of the previous aspects, the barrier layer includes a permeability of less than about 0.01 millidarcys. In another aspect combinable with any of the previous aspects, the barrier layer includes a brittleness of less than about 10 MPa, where brittleness includes a ratio of compressive stress of the barrier layer to tensile strength of the barrier layer. In another aspect combinable with any of the previous aspects, the barrier layer includes a thickness proximate the hazardous material storage drillhole portion of at least about 100 feet. In another aspect combinable with any of the previous aspects, the barrier layer includes a thickness proximate the hazardous material storage drillhole portion that inhibits diffusion of the hazardous material that escapes the storage canister through the barrier layer for an amount of time that is based on a half-life of the hazardous material. In another aspect combinable with any of the previous aspects, the barrier layer includes about 20 to 30% weight by volume of clay or organic matter. In another aspect combinable with any of the previous aspects, the barrier layer includes an impermeable layer. In another aspect combinable with any of the previous aspects, the barrier layer includes a leakage barrier defined by a time constant for leakage of the hazardous material of 10,000 years or more. In another aspect combinable with any of the previous aspects, the barrier layer includes a hydrocarbon or carbon dioxide bearing formation. In another aspect combinable with any of the previous aspects, the hazardous material includes spent nuclear fuel. Another aspect combinable with any of the previous aspects further includes at least one casing assembly that extends from at or proximate the terranean surface, through the drillhole, and into the hazardous material storage drillhole portion. In another aspect combinable with any of the previous aspects, the storage canister includes a connecting portion configured to couple to at least one of a downhole tool string or another storage canister. Another aspect combinable with any of the previous aspects further includes prior to moving the storage canister through the entry of the drillhole that extends into the terranean surface, forming the drillhole from the terranean surface to a subterranean formation. Another aspect combinable with any of the previous aspects further includes installing a casing in the drillhole that extends from at or proximate the terranean surface, through the drillhole, and into the hazardous material storage drillhole portion. Another aspect combinable with any of the previous aspects further includes cementing the casing to the drillhole. Another aspect combinable with any of the previous aspects further includes, subsequent to forming the drillhole, producing hydrocarbon fluid from the subterranean formation, through the drillhole, and to the terranean surface. Another aspect combinable with any of the previous aspects further includes removing the seal from the drillhole; and retrieving the storage canister from the hazardous material storage drillhole portion to the terranean surface. Another aspect combinable with any of the previous aspects further includes monitoring at least one variable associated with the storage canister from a sensor positioned proximate the hazardous material storage drillhole portion; and recording the monitored variable at the terranean surface. In another aspect combinable with any of the previous aspects, the monitored variable includes at least one of radiation level, temperature, pressure, presence of oxygen, presence of water vapor, presence of liquid water, acidity, or seismic activity. Another aspect combinable with any of the previous aspects further includes based on the monitored variable exceeding a threshold value removing the seal from the drillhole; and retrieving the storage canister from the hazardous material storage drillhole portion to the terranean surface. In another general implementation, a method for storing hazardous material includes moving a storage canister through an entry of a drillhole that extends into a terranean surface, the entry at least proximate the terranean surface, the storage canister including an inner cavity sized enclose hazardous material; moving the storage canister through the drillhole that includes a substantially vertical drillhole portion, a transition drillhole portion coupled to the substantially vertical drillhole portion, and a hazardous material storage drillhole portion coupled to the transition drillhole portion, the hazardous material storage drillhole portion located below a self-healing geological formation, the hazardous material storage drillhole portion vertically isolated, by the self-healing geological formation, from a subterranean zone that includes mobile water; moving the storage canister into the hazardous material storage drillhole portion; and forming a seal in the drillhole that isolates the storage portion of the drillhole from the entry of the drillhole. In an aspect combinable with the general implementation, the self-healing geologic formation includes at least one of shale, salt, clay, or dolomite. In another general implementation, a hazardous material storage repository includes a drillhole extending into the Earth and including an entry at least proximate a terranean surface, the drillhole including a substantially vertical drillhole portion, a transition drillhole portion coupled to the substantially vertical drillhole portion, and a hazardous material storage drillhole portion coupled to the transition drillhole portion, the hazardous material storage drillhole portion located below a self-healing geological formation, the hazardous material storage drillhole portion vertically isolated, by the self-healing geological formation, from a subterranean zone that includes mobile water; a storage canister positioned in the hazardous material storage drillhole portion, the storage canister sized to fit from the drillhole entry through the substantially vertical drillhole portion, the transition drillhole portion, and into the hazardous material storage drillhole portion of the drillhole, the storage canister including an inner cavity sized enclose hazardous material; and a seal positioned in the drillhole, the seal isolating the hazardous material storage drillhole portion of the drillhole from the entry of the drillhole. In an aspect combinable with the general implementation, the self-healing geologic formation includes at least one of shale, salt, clay, or dolomite. Implementations of a hazardous material storage repository according to the present disclosure may include one or more of the following features. For example, a hazardous material storage repository according to the present disclosure may allow for multiple levels of containment of hazardous material within a storage repository located thousands of feet underground, decoupled from any nearby mobile water. A hazardous material storage repository according to the present disclosure may also use proven techniques (e.g., drilling) to create or form a storage area for the hazardous material, in a subterranean zone proven to have fluidly sealed hydrocarbons therein for millions of years. As another example, a hazardous material storage repository according to the present disclosure may provide long-term (e.g., thousands of years) storage for hazardous material (e.g., radioactive waste) in a shale formation that has geologic properties suitable for such storage, including low permeability, thickness, and ductility, among others. In addition, a greater volume of hazardous material may be stored at low cost—relative to conventional storage techniques—due in part to directional drilling techniques that facilitate long horizontal boreholes, often exceeding a mile in length. In addition, rock formations that have geologic properties suitable for such storage may be found in close proximity to sites at which hazardous material may be found or generated, thereby reducing dangers associated with transporting such hazardous material. Implementations of a hazardous material storage repository according to the present disclosure may also include one or more of the following features. Large storage volumes, in turn, allow for the storage of hazardous materials to be emplaced without a need for complex prior treatment, such as concentration or transfer to different forms or canisters. As a further example, in the case of nuclear waste material from a reactor for instance, the waste can be kept in its original pellets, unmodified, or in its original fuel rods, or in its original fuel assemblies, which contain dozens of fuel rods. In another aspect, the hazardous material may be kept in an original holder but a cement or other material is injected into the holder to fill the gaps between the hazardous materials and the structure. For example, if the hazardous material is stored in fuel rods which are, in turn, stored in fuel assemblies, then the spaces between the rods (typically filled with water when inside a nuclear reactor) could be filled with cement or other material to provide yet an additional layer of isolation from the outside world. As yet a further example, secure and low cost storage of hazardous material is facilitated while still permitting retrieval of such material if circumstances deem it advantageous to recover the stored materials. The details of one or more implementations of the subject matter described in this disclosure are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages of the subject matter will become apparent from the description, the drawings, and the claims. FIG. 1A is a schematic illustration of example implementations of a hazardous material storage repository system, e.g., a subterranean location for the long-term (e.g., tens, hundreds, or thousands of years or more) but retrievable safe and secure storage of hazardous material, during a deposit or retrieval operation according to the present disclosure. For example, turning to FIG. 1A, this figure illustrates an example hazardous material storage repository system 100 during a deposit (or retrieval, as described below) process, e.g., during deployment of one or more canisters of hazardous material in a subterranean formation. As illustrated, the hazardous material storage repository system 100 includes a drillhole 104 formed (e.g., drilled or otherwise) from a terranean surface 102 and through multiple subterranean layers 112, 114, 116, and 132. Although the terranean surface 102 is illustrated as a land surface, terranean surface 102 may be a sub-sea or other underwater surface, such as a lake or an ocean floor or other surface under a body of water. Thus, the present disclosure contemplates that the drillhole 104 may be formed under a body of water from a drilling location on or proximate the body of water. The illustrated drillhole 104 is a directional drillhole in this example of hazardous material storage repository system 100. For instance, the drillhole 104 includes a substantially vertical portion 106 coupled to a radiussed or curved portion 108, which in turn is coupled to an inclined portion 110. As used in the present disclosure, “substantially” in the context of a drillhole orientation, refers to drillholes that may not be exactly vertical (e.g., exactly perpendicular to the terranean surface 102) or exactly horizontal (e.g., exactly parallel to the terranean surface 102), or exactly inclined at a particular incline angle relative to the terranean surface 102. In other words, vertical drillholes often undulate offset from a true vertical direction, that they might be drilled at an angle that deviates from true vertical, and inclined drillholes often undulate offset from a true incline angle. Further, in some aspects, an inclined drillhole may not have or exhibit an exactly uniform incline (e.g., in degrees) over a length of the drillhole. Instead, the incline of the drillhole may vary over its length (e.g., by 1-5 degrees). As illustrated in this example, the three portions of the drillhole 104—the vertical portion 106, the radiussed portion 108, and the inclined portion 110—form a continuous drillhole 104 that extends into the Earth. The illustrated drillhole 104, in this example, has a surface casing 120 positioned and set around the drillhole 104 from the terranean surface 102 into a particular depth in the Earth. For example, the surface casing 120 may be a relatively large-diameter tubular member (or string of members) set (e.g., cemented) around the drillhole 104 in a shallow formation. As used herein, “tubular” may refer to a member that has a circular cross-section, elliptical cross-section, or other shaped cross-section. For example, in this implementation of the hazardous material storage repository system 100, the surface casing 120 extends from the terranean surface through a surface layer 112. The surface layer 112, in this example, is a geologic layer comprised of one or more layered rock formations. In some aspects, the surface layer 112 in this example may or may not include freshwater aquifers, salt water or brine sources, or other sources of mobile water (e.g., water that moves through a geologic formation). In some aspects, the surface casing 120 may isolate the drillhole 104 from such mobile water, and may also provide a hanging location for other casing strings to be installed in the drillhole 104. Further, although not shown, a conductor casing may be set above the surface casing 120 (e.g., between the surface casing 120 and the surface 102 and within the surface layer 112) to prevent drilling fluids from escaping into the surface layer 112. As illustrated, a production casing 122 is positioned and set within the drillhole 104 downhole of the surface casing 120. Although termed a “production” casing, in this example, the casing 122 may or may not have been subject to hydrocarbon production operations. Thus, the casing 122 refers to and includes any form of tubular member that is set (e.g., cemented) in the drillhole 104 downhole of the surface casing 120. In some examples of the hazardous material storage repository system 100, the production casing 122 may begin at an end of the radiussed portion 108 and extend throughout the inclined portion 110. The casing 122 could also extend into the radiussed portion 108 and into the vertical portion 106. As shown, cement 130 is positioned (e.g., pumped) around the casings 120 and 122 in an annulus between the casings 120 and 122 and the drillhole 104. The cement 130, for example, may secure the casings 120 and 122 (and any other casings or liners of the drillhole 104) through the subterranean layers under the terranean surface 102. In some aspects, the cement 130 may be installed along the entire length of the casings (e.g., casings 120 and 122 and any other casings), or the cement 130 could be used along certain portions of the casings if adequate for a particular drillhole 102. The cement 130 can also provide an additional layer of confinement for the hazardous material in canisters 126. The drillhole 104 and associated casings 120 and 122 may be formed with various example dimensions and at various example depths (e.g., true vertical depth, or TVD). For instance, a conductor casing (not shown) may extend down to about 120 feet TVD, with a diameter of between about 28 in. and 60 in. The surface casing 120 may extend down to about 2500 feet TVD, with a diameter of between about 22 in. and 48 in. An intermediate casing (not shown) between the surface casing 120 and production casing 122 may extend down to about 8000 feet TVD, with a diameter of between about 16 in. and 36 in. The production casing 122 may extend inclinedly (e.g., to case the inclined portion 110) with a diameter of between about 11 in. and 22 in. The foregoing dimensions are merely provided as examples and other dimensions (e.g., diameters, TVDs, lengths) are contemplated by the present disclosure. For example, diameters and TVDs may depend on the particular geological composition of one or more of the multiple subterranean layers (112, 114, 116, and 132), particular drilling techniques, as well as a size, shape, or design of a hazardous material canister 126 that contains hazardous material to be deposited in the hazardous material storage repository system 100. In some alternative examples, the production casing 122 (or other casing in the drillhole 104) could be circular in cross-section, elliptical in cross-section, or some other shape. As illustrated, the vertical portion 106 of the drillhole 104 extends through subterranean layers 112, 114, 116, and 132, and, in this example, lands in a subterranean layer 119. As discussed above, the surface layer 112 may or may not include mobile water. Subterranean layer 114, which is below the surface layer 112, in this example, is a mobile water layer 114. For instance, mobile water layer 114 may include one or more sources of mobile water, such as freshwater aquifers, salt water or brine, or other source of mobile water. In this example of hazardous material storage repository system 100, mobile water may be water that moves through a subterranean layer based on a pressure differential across all or a part of the subterranean layer. For example, the mobile water layer 114 may be a permeable geologic formation in which water freely moves (e.g., due to pressure differences or otherwise) within the layer 114. In some aspects, the mobile water layer 114 may be a primary source of human-consumable water in a particular geographic area. Examples of rock formations of which the mobile water layer 114 may be composed include porous sandstones and limestones, among other formations. Other illustrated layers, such as the impermeable layer 116 and the storage layer 119, may include immobile water. Immobile water, in some aspects, is water (e.g., fresh, salt, brine), that is not fit for human or animal consumption, or both. Immobile water, in some aspects, may be water that, by its motion through the layers 116 or 119 (or both), cannot reach the mobile water layer 114, terranean surface 102, or both, within 10,000 years or more (such as to 1,000,000 years). Below the mobile water layer 114, in this example implementation of hazardous material storage repository system 100, is an impermeable layer 116. The impermeable layer 116, in this example, may not allow mobile water to pass through. Thus, relative to the mobile water layer 114, the impermeable layer 116 may have low permeability, e.g., on the order of nanodarcy permeability. Additionally, in this example, the impermeable layer 116 may be a relatively non-ductile (i.e., brittle) geologic formation. One measure of non-ductility is brittleness, which is the ratio of compressive stress to tensile strength. In some examples, the brittleness of the impermeable layer 116 may be between about 20 MPa and 40 MPa. As shown in this example, the impermeable layer 116 is shallower (e.g., closer to the terranean surface 102) than the storage layer 119. In this example rock formations of which the impermeable layer 116 may be composed include, for example, certain kinds of sandstone, mudstone, clay, and slate that exhibit permeability and brittleness properties as described above. In alternative examples, the impermeable layer 116 may be deeper (e.g., further from the terranean surface 102) than the storage layer 119. In such alternative examples, the impermeable layer 116 may be composed of an igneous rock, such as granite. Below the impermeable layer 116 is the storage layer 119. The storage layer 119, in this example, may be chosen as the landing for the inclined portion 110, which stores the hazardous material, for several reasons. Relative to the impermeable layer 116 or other layers, the storage layer 119 may be thick, e.g., between about 100 and 200 feet of total vertical thickness. Thickness of the storage layer 119 may allow for easier landing and directional drilling, thereby allowing the inclined portion 110 to be readily emplaced within the storage layer 119 during constructions (e.g., drilling). If formed through an approximate horizontal center of the storage layer 119, the inclined portion 110 may be surrounded by about 50 to 100 feet of the geologic formation that comprises the storage layer 119. Further, the storage layer 119 may also have only immobile water, e.g., due to a very low permeability of the layer 119 (e.g., on the order of milli- or nanodarcys). In addition, the storage layer 119 may have sufficient ductility, such that a brittleness of the rock formation that comprises the layer 119 is between about 3 MPa and 10 MPa. Examples of rock formations of which the storage layer 119 may be composed include: shale and anhydrite. Further, in some aspects, hazardous material may be stored below the storage layer, even in a permeable formation such as sandstone or limestone, if the storage layer is of sufficient geologic properties to isolate the permeable layer from the mobile water layer 114. In some examples implementations of the hazardous material storage repository system 100, the storage layer 119 (and/or the impermeable layer 116) is composed of shale. Shale, in some examples, may have properties that fit within those described above for the storage layer 119. For example, shale formations may be suitable for a long-term confinement of hazardous material (e.g., in the hazardous material canisters 126), and for their isolation from mobile water layer 114 (e.g., aquifers) and the terranean surface 102. Shale formations may be found relatively deep in the Earth, typically 3000 feet or greater, and placed in isolation below any fresh water aquifers. Other formations may include salt or other impermeable formation layer. Shale formations (or salt or other impermeable formation layers), for instance, may include geologic properties that enhance the long-term (e.g., thousands of years) isolation of material. Such properties, for instance, have been illustrated through the long term storage (e.g., tens of millions of years) of hydrocarbon fluids (e.g., gas, liquid, mixed phase fluid) without escape of substantial fractions of such fluids into surrounding layers (e.g., mobile water layer 114). Indeed, shale has been shown to hold natural gas for millions of years or more, giving it a proven capability for long-term storage of hazardous material. Example shale formations (e.g., Marcellus, Eagle Ford, Barnett, and otherwise) has stratification that contains many redundant sealing layers that have been effective in preventing movement of water, oil, and gas for millions of years, lacks mobile water, and can be expected (e.g., based on geological considerations) to seal hazardous material (e.g., fluids or solids) for thousands of years after deposit. In some aspects, the formation of the storage layer 119 and/or the impermeable layer 116 may form a leakage barrier, or barrier layer to fluid leakage that may be determined, at least in part, by the evidence of the storage capacity of the layer for hydrocarbons or other fluids (e.g., carbon dioxide) for hundreds of years, thousands of years, tens of thousands of years, hundreds of thousands of years, or even millions of years. For example, the barrier layer of the storage layer 119 and/or impermeable layer 116 may be defined by a time constant for leakage of the hazardous material more than 10,000 years (such as between about 10,000 years and 1,000,000 years) based on such evidence of hydrocarbon or other fluid storage. Shale (or salt or other impermeable layer) formations may also be at a suitable depth, e.g., between 3000 and 12,000 feet TVD. Such depths are typically below ground water aquifer (e.g., surface layer 112 and/or mobile water layer 114). Further, the presence of soluble elements in shale, including salt, and the absence of these same elements in aquifer layers, demonstrates a fluid isolation between shale and the aquifer layers. Another particular quality of shale that may advantageously lend itself to hazardous material storage is its clay content, which, in some aspects, provides a measure of ductility greater than that found in other, impermeable rock formations (e.g., impermeable layer 116). For example, shale may be stratified, made up of thinly alternating layers of clays (e.g., between about 20-30% clay by volume) and other minerals. Such a composition may make shale less brittle and, thus less susceptible to fracturing (e.g., naturally or otherwise) as compared to rock formations in the impermeable layer (e.g., dolomite or otherwise). For example, rock formations in the impermeable layer 116 may have suitable permeability for the long term storage of hazardous material, but are too brittle and commonly are fractured. Thus, such formations may not have sufficient sealing qualities (as evidenced through their geologic properties) for the long term storage of hazardous material. The present disclosure contemplates that there may be many other layers between or among the illustrated subterranean layers 112, 114, 116, and 119. For example, there may be repeating patterns (e.g., vertically), of one or more of the mobile water layer 114, impermeable layer 116, and storage layer 119. Further, in some instances, the storage layer 119 may be directly adjacent (e.g., vertically) the mobile water layer 114, i.e., without an intervening impermeable layer 116. In some examples, all or portions of the radiussed drillhole 108 and the inclined drillhole 110 may be formed below the storage layer 119, such that the storage layer 119 (e.g., shale or other geologic formation with characteristics as described herein) is vertically positioned between the inclined drillhole 110 and the mobile water layer 114. Further, in this example implementation, a self-healing layer 132 may be found below the terranean surface 102 and between, for example, the surface 102 and one or both of the impermeable layer 116 and the storage layer 119. In some aspects, the self-healing layer 132 may comprise a geologic formation that can stop or impede a flow of hazardous material (whether in liquid, solid, or gaseous form) from a storage portion of the drillhole 104 to or toward the terranean surface 102. For example, during formation of the drillhole 104 (e.g., drilling), all are portions of the geologic formations of the layers 112, 114, 116, and 119, may be damaged (as illustrated by a damaged zone 140), thereby affecting or changing their geologic characteristics (e.g., permeability). Indeed, although damaged zone 140 is illustrated between layers 114 and 132 for simplicity sake, the damaged zone 140 may surround an entire length (vertical, curved, and inclined portions) of the drillhole 104 a particular distance into the layers 112, 114, 116, 119, 132, and otherwise. In certain aspects, the location of the drillhole 104 may be selected so as to be formed through the self-healing layer 132. For example, as shown, the drillhole 104 may be formed such that at least a portion of the vertical portion 106 of the drillhole 104 is formed to pass through the self-healing layer 132. In some aspects, the self-healing layer 132 comprises a geologic formation that that does not sustain cracks for extended time durations even after being drilled therethrough. Examples of the geologic formation in the self-healing layer 132 include clay or dolomite. Cracks in such rock formations tend to heal, that is, they disappear rapidly with time due to the relative ductility of the material, and the enormous pressures that occur underground from the weight of the overlying rock on the formation in the self-healing layer. In addition to providing a “healing mechanism” for cracks that occur due to the formation of the drillhole 104 (e.g., drilling or otherwise), the self-healing layer 132 may also provide a barrier to natural faults and other cracks that otherwise could provide a pathway for hazardous material leakage (e.g., fluid or solid) from the storage region (e.g., in the inclined portion 110) to the terranean surface 102, the mobile water layer 114, or both. As shown in this example, the inclined portion 110 of the drillhole 104 includes a storage area 117 in a distal part of the portion 110 into which hazardous material may be retrievably placed for long-term storage. For example, as shown, a work string 124 (e.g., tubing, coiled tubing, wireline, or otherwise) may be extended into the cased drillhole 104 to place one or more (three shown but there may be more or less) hazardous material canisters 126 into long term, but in some aspects, retrievable, storage in the portion 110. For example, in the implementation shown in FIG. 1A, the work string 124 may include a downhole tool 128 that couples to the canister 126, and with each trip into the drillhole 104, the downhole tool 128 may deposit a particular hazardous material canister 126 in the inclined portion 110. The downhole tool 128 may couple to the canister 126 by, in some aspects, a threaded connection or other type of connection, such as a latched connection. In alternative aspects, the downhole tool 128 may couple to the canister 126 with an interlocking latch, such that rotation (or linear movement or electric or hydraulic switches) of the downhole tool 128 may latch to (or unlatch from) the canister 126. In alternative aspects, the downhole tool 124 may include one or more magnets (e.g., rare Earth magnets, electromagnets, a combination thereof, or otherwise) which attractingly couple to the canister 126. In some examples, the canister 126 may also include one or more magnets (e.g., rare Earth magnets, electromagnets, a combination thereof, or otherwise) of an opposite polarity as the magnets on the downhole tool 124. In some examples, the canister 126 may be made from or include a ferrous or other material attractable to the magnets of the downhole tool 124. As another example, each canister 126 may be positioned within the drillhole 104 by a drillhole tractor (e.g., on a wireline or otherwise), which may push or pull the canister into the inclined portion 110 through motorized (e.g., electric) motion. As yet another example, each canister 126 may include or be mounted to rollers (e.g., wheels), so that the downhole tool 124 may push the canister 126 into the cased drillhole 104. In some example implementations, the canister 126, one or more of the drillhole casings 120 and 122, or both, may be coated with a friction-reducing coating prior to the deposit operation. For example, by applying a coating (e.g., petroleum-based product, resin, ceramic, or otherwise) to the canister 126 and/or drillhole casings, the canister 126 may be more easily moved through the cased drillhole 104 into the inclined portion 110. In some aspects, only a portion of the drillhole casings may be coated. For example, in some aspects, the substantially vertical portion 106 may not be coated, but the radiussed portion 108 or the inclined portion 110, or both, may be coated to facilitate easier deposit and retrieval of the canister 126. FIG. 1A also illustrates an example of a retrieval operation of hazardous material in the inclined portion 110 of the drillhole 104. A retrieval operation may be the opposite of a deposit operation, such that the downhole tool 124 (e.g., a fishing tool) may be run into the drillhole 104, coupled to the last-deposited canister 126 (e.g., threadingly, latched, by magnet, or otherwise), and pull the canister 126 to the terranean surface 102. Multiple retrieval trips may be made by the downhole tool 124 in order to retrieve multiple canisters from the inclined portion 110 of the drillhole 104. Each canister 126 may enclose hazardous material. Such hazardous material, in some examples, may be biological or chemical waste or other biological or chemical hazardous material. In some examples, the hazardous material may include nuclear material, such as spent nuclear fuel recovered from a nuclear reactor (e.g., commercial power or test reactor) or military nuclear material. For example, a gigawatt nuclear plant may produce 30 tons of spent nuclear fuel per year. The density of that fuel is typically close to 10 (10 gm/cm3=10 kg/liter), so that the volume for a year of nuclear waste is about 3 m3. Spent nuclear fuel, in the form of nuclear fuel pellets, may be taken from the reactor and not modified. Nuclear fuel pellet are solid, although they can contain and emit a variety of radioactive gases including tritium (13 year half-life), krypton-85 (10.8 year half-life), and carbon dioxide containing C-14 (5730 year half-life). In some aspects, the storage layer 119 should be able to contain any radioactive output (e.g., gases) within the layer 119, even if such output escapes the canisters 126. For example, the storage layer 119 may be selected based on diffusion times of radioactive output through the layer 119. For example, a minimum diffusion time of radioactive output escaping the storage layer 119 may be set at, for example, fifty times a half-life for any particular component of the nuclear fuel pellets. Fifty half-lives as a minimum diffusion time would reduce an amount of radioactive output by a factor of 1×10−15. As another example, setting a minimum diffusion time to thirty half-lives would reduce an amount of radioactive output by a factor of one billion. For example, plutonium-239 is often considered a dangerous waste product in spent nuclear fuel because of its long half-life of 24,100 years. For this isotope, 50 half-lives would be 1.2 million years. Plutonium-239 has low solubility in water, is not volatile, and as a solid. its diffusion time is exceedingly small (e.g., many millions of years) through a matrix of the rock formation that comprises the illustrated storage layer 119 (e.g., shale or other formation). The storage layer 119, for example comprised of shale, may offer the capability to have such isolation times (e.g., millions of years) as shown by the geological history of containing gaseous hydrocarbons (e.g., methane and otherwise) for several million years. In contrast, in conventional nuclear material storage methods, there was a danger that some plutonium might dissolve in a layer that comprised mobile ground water upon confinement escape. As further shown in FIG. 1A, the storage canisters 126 may be positioned for long term storage in the inclined portion 110, which, as shown, is tilted upward at a small angle (e.g., 2-5 degrees) as it gets further away from the vertical portion 106 of the drillhole 104. As illustrated, the inclined portion 110 tilts upward toward the terranean surface 102. In some aspects, for example when there is radioactive hazardous material stored in the canisters 126, the inclination of the drillhole portion 110 may provide a further degree of safety and containment to prevent or impede the material, even if leaked from the canister 126, from reaching, e.g., the mobile water layer 114, the vertical portion 106 of the drillhole 104, the terranean surface 102, or a combination thereof. For example, radionuclides of concern in the hazardous material tend to be relatively buoyant or heavy (as compared to brine or other fluids that might fill the drillhole). Buoyant radionuclides may be the greatest concern for leakage, since heavy elements and molecules tend to sink, and would not diffuse upward towards the terranean surface 102. Krypton gas, and particularly 14CO2 (where 14C refers to radiocarbon, also called C-14, which is an isotope of carbon with a half-life of 5730 years), is a buoyant radioactive element that is heavier than air (as are most gases) but much lighter than water. Thus, should 14CO2 be introduced into a water bath, such gas would tend to float upward towards the terranean surface 102. Iodine, on the other hand, is denser than water, and would tend to diffuse downward if introduced into a water bath. By including the inclined portion 110 of the drillhole 104, any such diffusion of radioactive material (e.g., even if leaked from a canister 126 and in the presence of water or other liquid in the drillhole 104 or otherwise) would be directed angularly upward toward a distal end 121 of the inclined portion 110 and away from the radiussed portion 108 (and the vertical portion 106) of the drillhole 104. Thus, leaked hazardous material, even in a diffusible gas form, would not be offered a path (e.g., directly) to the terranean surface 102 (or the mobile water layer 114) through the vertical portion 106 of the drillhole 110. For instance, the leaked hazardous material (especially in gaseous form) would be directed and gathered at the distal end 121 of the drillhole portion 110. Alternative methods of depositing the canisters 126 into the inclined drillhole portion 110 may also be implemented. For instance, a fluid (e.g., liquid or gas) may be circulated through the drillhole 104 to fluidly push the canisters 126 into the inclined drillhole portion 110. In some example, each canister 126 may be fluidly pushed separately. In alternative aspects, two or more canisters 126 may be fluidly pushed, simultaneously, through the drillhole 104 for deposit into the inclined portion 110. The fluid can be, in some cases, water. Other examples include a drilling mud or drilling foam. In some examples, a gas may be used to push the canisters 126 into the drillhole, such as air, argon, or nitrogen. In some aspects, the choice of fluid may depend at least in part on a viscosity of the fluid. For example, a fluid may be chosen with enough viscosity to impede the drop of the canister 126 into the substantially vertical portion 106. This resistance or impedance may provide a safety factor against a sudden drop of the canister 126. The fluid may also provide lubrication to reduce a sliding friction between the canister 126 and the casings 120 and 122. The canister 126 can be conveyed within a casing filled with a liquid of controlled viscosity, density, and lubricant qualities. The fluid-filled annulus between the inner diameter of the casings 120 and 122 and the outer diameter of the conveyed canister 126 represents an opening designed to dampen any high rate of canister motion, providing automatic passive protection in an unlikely decoupling of the conveyed canister 126. In some aspects, other techniques may be employed to facilitate deposit of the canister 126 into the inclined portion 110. For example, one or more of the installed casings (e.g., casings 120 and 122) may have rails to guide the storage canister 126 into the drillhole 102 while reducing friction between the casings and the canister 126. The storage canister 126 and the casings (or the rails) may be made of materials that slide easily against one another. The casings may have a surface that is easily lubricated, or one that is self-lubricating when subjected to the weight of the storage canister 126. The fluid may also be used for retrieval of the canister 126. For example, in an example retrieval operation, a volume within the casings 120 and 122 may be filled with a compressed gas (e.g., air, nitrogen, argon, or otherwise). As the pressure increases at an end of the inclined portion 110, the canisters 126 may be pushed toward the radiussed portion 108, and subsequently through the substantially vertical portion 106 to the terranean surface. In some aspects, the drillhole 104 may be formed for the primary purpose of long-term storage of hazardous materials. In alternative aspects, the drillhole 104 may have been previously formed for the primary purpose of hydrocarbon production (e.g., oil, gas). For example, storage layer 119 may be a hydrocarbon bearing formation from which hydrocarbons were produced into the drillhole 104 and to the terranean surface 102. In some aspects, the storage layer 119 may have been hydraulically fractured prior to hydrocarbon production. Further in some aspects, the production casing 122 may have been perforated prior to hydraulic fracturing. In such aspects, the production casing 122 may be patched (e.g., cemented) to repair any holes made from the perforating process prior to a deposit operation of hazardous material. In addition, any cracks or openings in the cement between the casing and the drillhole can also be filled at that time. For example, in the case of spent nuclear fuel as a hazardous material, the drillhole may be formed at a particular location, e.g., near a nuclear power plant, as a new drillhole provided that the location also includes an appropriate storage layer 119, such as a shale formation. Alternatively, an existing well that has already produced shale gas, or one that was abandoned as “dry,” (e.g., with sufficiently low organics that the gas in place is too low for commercial development), may be selected as the drillhole 104. In some aspects, prior hydraulic fracturing of the storage layer 119 through the drillhole 104 may make little difference in the hazardous material storage capability of the drillhole 104. But such a prior activity may also confirm the ability of the storage layer 119 to store gases and other fluids for millions of years. If, therefore, the hazardous material or output of the hazardous material (e.g., radioactive gasses or otherwise) were to escape from the canister 126 and enter the fractured formation of the storage layer 119, such fractures may allow that material to spread relatively rapidly over a distance comparable in size to that of the fractures. In some aspects, the drillhole 102 may have been drilled for a production of hydrocarbons, but production of such hydrocarbons had failed, e.g., because the storage layer 119 comprised a rock formation (e.g., shale or otherwise) that was too ductile and difficult to fracture for production, but was advantageously ductile for the long-term storage of hazardous material. FIG. 1B is a schematic illustration of a portion of the example implementation of the hazardous material storage repository system 100 that shows an example determination of a minimum angle of the inclined portion 110 of the hazardous material storage repository system 100. For example, as shown in system 100, the inclined portion 110 provides that any path that leaking hazardous material (e.g., from one or more of the canister 126) takes to the terranean surface 102 through the drillhole 104 includes at least one downward component. In this case, the inclined portion 110 is the downward component. In other example implementations described later, such as systems 200 and 300, other portions (e.g., a J-section portion or undulating portion) may include at least one downward component. Such paths, as shown in this example, dip below a horizontal escape limit line 175 that intersects a canister 126 that is closest (when positioned in the storage area 117) to the vertical portion 106 of the drillhole 104. and therefore must include a downward component. In some aspects, an angle, a, of the inclined portion 110 of the drillhole 104 may be determined (and thereby guide the formation of the drillhole 104) according to a radius, R, of the damaged zone 140 of the drillhole 104 and a distance, D, from the canister 126 that is closest to the vertical portion 106 of the drillhole 104. As shown in the callout bubble in FIG. 1B, with knowledge of the distances R and D (or at least estimates), then the angle, a, can be computed according to the arctangent of R/D. In an example implementation, R may be about 1 meter while D may be about 20 meters. The angle, a, therefore, as the arctangent of R/D is about 3°. This is just one example of the determination of the angle, a, of a downward component (e.g., the inclined portion 110) of the drillhole 104 to ensure that such a downward component dips below the horizontal escape limit line 175. FIG. 2 is a schematic illustration of example implementations of another hazardous material storage repository system, e.g., a subterranean location for the long-term (e.g., tens, hundreds, or thousands of years or more) but retrievable safe and secure storage of hazardous material, during a deposit or retrieval operation according to the present disclosure. For example, turning to FIG. 2, this figure illustrates an example hazardous material storage repository system 200 during a deposit (or retrieval, as described below) process, e.g., during deployment of one or more canisters of hazardous material in a subterranean formation. As illustrated, the hazardous material storage repository system 200 includes a drillhole 204 formed (e.g., drilled or otherwise) from a terranean surface 202 and through multiple subterranean layers 212, 214, and 216. Although the terranean surface 202 is illustrated as a land surface, terranean surface 202 may be a sub-sea or other underwater surface, such as a lake or an ocean floor or other surface under a body of water. Thus, the present disclosure contemplates that the drillhole 204 may be formed under a body of water from a drilling location on or proximate the body of water. The illustrated drillhole 204 is a directional drillhole in this example of hazardous material storage repository system 200. For instance, the drillhole 204 includes a substantially vertical portion 206 coupled to a J-section portion 208, which in turn is coupled to a substantially horizontal portion 210. The J-section portion 208 as shown, has a shape that resembles the bottom portion of the letter “J” and may be shaped similar to a p-trap device used in a plumbing system that is used to prevent gasses from migrating from one side of the bend to the other side of the bend. As used in the present disclosure, “substantially” in the context of a drillhole orientation, refers to drillholes that may not be exactly vertical (e.g., exactly perpendicular to the terranean surface 202) or exactly horizontal (e.g., exactly parallel to the terranean surface 202), or exactly inclined at a particular incline angle relative to the terranean surface 202. In other words, vertical drillholes often undulate offset from a true vertical direction, that they might be drilled at an angle that deviates from true vertical, and horizontal drillholes often undulate offset from exactly horizontal. As illustrated in this example, the three portions of the drillhole 204—the vertical portion 206, the J-section portion 208, and the substantially horizontal portion 210—form a continuous drillhole 204 that extends into the Earth. As also shown in dashed line in FIG. 2, the J-section portion 208 may be coupled to an inclined portion 240 rather than (or in addition to) the substantially horizontal portion 210 of the drillhole 204. The illustrated drillhole 204, in this example, has a surface casing 220 positioned and set around the drillhole 204 from the terranean surface 202 into a particular depth in the Earth. For example, the surface casing 220 may be a relatively large-diameter tubular member (or string of members) set (e.g., cemented) around the drillhole 204 in a shallow formation. As used herein, “tubular” may refer to a member that has a circular cross-section, elliptical cross-section, or other shaped cross-section. For example, in this implementation of the hazardous material storage repository system 200, the surface casing 220 extends from the terranean surface through a surface layer 212. The surface layer 212, in this example, is a geologic layer comprised of one or more layered rock formations. In some aspects, the surface layer 212 in this example may or may not include freshwater aquifers, salt water or brine sources, or other sources of mobile water (e.g., water that moves through a geologic formation). In some aspects, the surface casing 220 may isolate the drillhole 204 from such mobile water, and may also provide a hanging location for other casing strings to be installed in the drillhole 204. Further, although not shown, a conductor casing may be set above the surface casing 220 (e.g., between the surface casing 220 and the surface 202 and within the surface layer 212) to prevent drilling fluids from escaping into the surface layer 212. As illustrated, a production casing 222 is positioned and set within the drillhole 204 downhole of the surface casing 220. Although termed a “production” casing, in this example, the casing 222 may or may not have been subject to hydrocarbon production operations. Thus, the casing 222 refers to and includes any form of tubular member that is set (e.g., cemented) in the drillhole 204 downhole of the surface casing 220. In some examples of the hazardous material storage repository system 200, the production casing 222 may begin at an end of the J-section portion 208 and extend throughout the substantially horizontal portion 210. The casing 222 could also extend into the J-section portion 208 and into the vertical portion 206. As shown, cement 230 is positioned (e.g., pumped) around the casings 220 and 222 in an annulus between the casings 220 and 222 and the drillhole 204. The cement 230, for example, may secure the casings 220 and 222 (and any other casings or liners of the drillhole 204) through the subterranean layers under the terranean surface 202. In some aspects, the cement 230 may be installed along the entire length of the casings (e.g., casings 220 and 222 and any other casings), or the cement 230 could be used along certain portions of the casings if adequate for a particular drillhole 202. The cement 230 can also provide an additional layer of confinement for the hazardous material in canisters 226. The drillhole 204 and associated casings 220 and 222 may be formed with various example dimensions and at various example depths (e.g., true vertical depth, or TVD). For instance, a conductor casing (not shown) may extend down to about 120 feet TVD, with a diameter of between about 28 in. and 60 in. The surface casing 220 may extend down to about 2500 feet TVD, with a diameter of between about 22 in. and 48 in. An intermediate casing (not shown) between the surface casing 220 and production casing 222 may extend down to about 8000 feet TVD, with a diameter of between about 16 in. and 36 in. The production casing 222 may extend inclinedly (e.g., to case the substantially horizontal portion 210 and/or the inclined portion 240) with a diameter of between about 11 in. and 22 in. The foregoing dimensions are merely provided as examples and other dimensions (e.g., diameters, TVDs, lengths) are contemplated by the present disclosure. For example, diameters and TVDs may depend on the particular geological composition of one or more of the multiple subterranean layers (212, 214, and 216), particular drilling techniques, as well as a size, shape, or design of a hazardous material canister 226 that contains hazardous material to be deposited in the hazardous material storage repository system 200. In some alternative examples, the production casing 222 (or other casing in the drillhole 204) could be circular in cross-section, elliptical in cross-section, or some other shape. As illustrated, the vertical portion 206 of the drillhole 204 extends through subterranean layers 212, 214, and 216, and, in this example, lands in a subterranean layer 219. As discussed above, the surface layer 212 may or may not include mobile water. Subterranean layer 214, which is below the surface layer 212, in this example, is a mobile water layer 214. For instance, mobile water layer 214 may include one or more sources of mobile water, such as freshwater aquifers, salt water or brine, or other source of mobile water. In this example of hazardous material storage repository system 200, mobile water may be water that moves through a subterranean layer based on a pressure differential across all or a part of the subterranean layer. For example, the mobile water layer 214 may be a permeable geologic formation in which water freely moves (e.g., due to pressure differences or otherwise) within the layer 214. In some aspects, the mobile water layer 214 may be a primary source of human-consumable water in a particular geographic area. Examples of rock formations of which the mobile water layer 214 may be composed include porous sandstones and limestones, among other formations. Other illustrated layers, such as the impermeable layer 216 and the storage layer 219, may include immobile water. Immobile water, in some aspects, is water (e.g., fresh, salt, brine), that is not fit for human or animal consumption, or both. Immobile water, in some aspects, may be water that, by its motion through the layers 216 or 219 (or both), cannot reach the mobile water layer 214, terranean surface 202, or both, within 10,000 years or more (such as to 1,000,000 years). Below the mobile water layer 214, in this example implementation of hazardous material storage repository system 200, is an impermeable layer 216. The impermeable layer 216, in this example, may not allow mobile water to pass through. Thus, relative to the mobile water layer 214, the impermeable layer 216 may have low permeability, e.g., on the order of 0.01 millidarcy permeability. Additionally, in this example, the impermeable layer 216 may be a relatively non-ductile (i.e., brittle) geologic formation. One measure of non-ductility is brittleness, which is the ratio of compressive stress to tensile strength. In some examples, the brittleness of the impermeable layer 216 may be between about 20 MPa and 40 MPa. As shown in this example, the impermeable layer 216 is shallower (e.g., closer to the terranean surface 202) than the storage layer 219. In this example rock formations of which the impermeable layer 216 may be composed include, for example, certain kinds of sandstone, mudstone, clay, and slate that exhibit permeability and brittleness properties as described above. In alternative examples, the impermeable layer 216 may be deeper (e.g., further from the terranean surface 202) than the storage layer 219. In such alternative examples, the impermeable layer 216 may be composed of an igneous rock, such as granite. Below the impermeable layer 216 is the storage layer 219. The storage layer 219, in this example, may be chosen as the landing for the substantially horizontal portion 210, which stores the hazardous material, for several reasons. Relative to the impermeable layer 216 or other layers, the storage layer 219 may be thick, e.g., between about 100 and 200 feet of total vertical thickness. Thickness of the storage layer 219 may allow for easier landing and directional drilling, thereby allowing the substantially horizontal portion 210 to be readily emplaced within the storage layer 219 during constructions (e.g., drilling). If formed through an approximate horizontal center of the storage layer 219, the substantially horizontal portion 210 may be surrounded by about 50 to 100 feet of the geologic formation that comprises the storage layer 219. Further, the storage layer 219 may also have only immobile water, e.g., due to a very low permeability of the layer 219 (e.g., on the order of milli- or nanodarcys). In addition, the storage layer 219 may have sufficient ductility, such that a brittleness of the rock formation that comprises the layer 219 is between about 3 MPa and 10 MPa. Examples of rock formations of which the storage layer 219 may be composed include: shale and anhydrite. Further, in some aspects, hazardous material may be stored below the storage layer, even in a permeable formation such as sandstone or limestone, if the storage layer is of sufficient geologic properties to isolate the permeable layer from the mobile water layer 214. In some examples implementations of the hazardous material storage repository system 200, the storage layer 219 (and/or the impermeable layer 216) is composed of shale. Shale, in some examples, may have properties that fit within those described above for the storage layer 219. For example, shale formations may be suitable for a long-term confinement of hazardous material (e.g., in the hazardous material canisters 226), and for their isolation from mobile water layer 214 (e.g., aquifers) and the terranean surface 202. Shale formations may be found relatively deep in the Earth, typically 3000 feet or greater, and placed in isolation below any fresh water aquifers. Other formations may include salt or other impermeable formation layer. Shale formations (or salt or other impermeable formation layers), for instance, may include geologic properties that enhance the long-term (e.g., thousands of years) isolation of material. Such properties, for instance, have been illustrated through the long term storage (e.g., tens of millions of years) of hydrocarbon fluids (e.g., gas, liquid, mixed phase fluid) without escape of such fluids into surrounding layers (e.g., mobile water layer 214). Indeed, shale has been shown to hold natural gas for millions of years or more, giving it a proven capability for long-term storage of hazardous material. Example shale formations (e.g., Marcellus, Eagle Ford, Barnett, and otherwise) has stratification that contains many redundant sealing layers that have been effective in preventing movement of water, oil, and gas for millions of years, lacks mobile water, and can be expected (e.g., based on geological considerations) to seal hazardous material (e.g., fluids or solids) for thousands of years after deposit. In some aspects, the formation of the storage layer 219 and/or the impermeable layer 216 may form a leakage barrier, or barrier layer to fluid leakage that may be determined, at least in part, by the evidence of the storage capacity of the layer for hydrocarbons or other fluids (e.g., carbon dioxide) for hundreds of years, thousands of years, tens of thousands of years, hundreds of thousands of years, or even millions of years. For example, the barrier layer of the storage layer 219 and/or impermeable layer 216 may be defined by a time constant for leakage of the hazardous material of more than 10,000 years (such as between 10,000 years and 1,000,000 years) based on such evidence of hydrocarbon or other fluid storage. Shale (or salt or other impermeable layer) formations may also be at a suitable depth, e.g., between 3000 and 12,000 feet TVD. Such depths are typically below ground water aquifer (e.g., surface layer 212 and/or mobile water layer 214). Further, the presence of soluble elements in shale, including salt, and the absence of these same elements in aquifer layers, demonstrates a fluid isolation between shale and the aquifer layers. Another particular quality of shale that may advantageously lend itself to hazardous material storage is its clay content, which, in some aspects, provides a measure of ductility greater than that found in other, impermeable rock formations (e.g., impermeable layer 216). For example, shale may be stratified, made up of thinly alternating layers of clays (e.g., between about 20-30% clay by volume) and other minerals. Such a composition may make shale less brittle and, thus less susceptible to fracturing (e.g., naturally or otherwise) as compared to rock formations in the impermeable layer (e.g., dolomite or otherwise). For example, rock formations in the impermeable layer 216 may have suitable permeability for the long term storage of hazardous material, but are too brittle and commonly are fractured. Thus, such formations may not have sufficient sealing qualities (as evidenced through their geologic properties) for the long term storage of hazardous material. The present disclosure contemplates that there may be many other layers between or among the illustrated subterranean layers 212, 214, 216, and 219. For example, there may be repeating patterns (e.g., vertically), of one or more of the mobile water layer 214, impermeable layer 216, and storage layer 219. Further, in some instances, the storage layer 219 may be directly adjacent (e.g., vertically) the mobile water layer 214, i.e., without an intervening impermeable layer 216. In some examples, all or portions of the J-section drillhole 208 and the substantially horizontal portion 210 (and/or the inclined portion 240) may be formed below the storage layer 219, such that the storage layer 219 (e.g., shale or other geologic formation with characteristics as described herein) is vertically positioned between the substantially horizontal portion 210 (and/or the inclined portion 240) and the mobile water layer 214. Although not illustrated in this particular example shown in FIG. 2, a self-healing layer (e.g., such as the self-healing layer 132) may be found below the terranean surface 202 and between, for example, the surface 202 and one or both of the impermeable layer 216 and the storage layer 219. In some aspects, the self-healing layer may comprise a geologic formation that can stop or impede a flow of hazardous material (whether in liquid, solid, or gaseous form) from a storage portion of the drillhole 204 to or toward the terranean surface 202. For example, during formation of the drillhole 204 (e.g., drilling), all are portions of the geologic formations of the layers 212, 214, 216, and 219, may be damaged, thereby affecting or changing their geologic characteristics (e.g., permeability). In certain aspects, the location of the drillhole 204 may be selected so as to be formed through the self-healing layer. For example, as shown, the drillhole 204 may be formed such that at least a portion of the vertical portion 206 of the drillhole 204 is formed to pass through the self-healing layer. In some aspects, the self-healing layer comprises a geologic formation that that does not sustain cracks for extended time durations even after being drilled therethrough. Examples of the geologic formation in the self-healing layer include clay or dolomite. Cracks in such rock formations tend to heal, that is, they disappear rapidly with time due to the relative ductility of the material, and the enormous pressures that occur underground from the weight of the overlying rock on the formation in the self-healing layer. In addition to providing a “healing mechanism” for cracks that occur due to the formation of the drillhole 204 (e.g., drilling or otherwise), the self-healing layer may also provide a barrier to natural faults and other cracks that otherwise could provide a pathway for hazardous material leakage (e.g., fluid or solid) from the storage region (e.g., in the substantially horizontal portion 210) to the terranean surface 202, the mobile water layer 214, or both. As shown in this example, the substantially horizontal portion 210 of the drillhole 204 includes a storage area 217 in a distal part of the portion 210 into which hazardous material may be retrievably placed for long-term storage. For example, as shown, a work string 224 (e.g., tubing, coiled tubing, wireline, or otherwise) may be extended into the cased drillhole 204 to place one or more (three shown but there may be more or less) hazardous material canisters 226 into long term, but in some aspects, retrievable, storage in the portion 210. For example, in the implementation shown in FIG. 2, the work string 224 may include a downhole tool 228 that couples to the canister 226, and with each trip into the drillhole 204, the downhole tool 228 may deposit a particular hazardous material canister 226 in the substantially horizontal portion 210. The downhole tool 228 may couple to the canister 226 by, in some aspects, a threaded connection or other type of connection, such as a latched connection. In alternative aspects, the downhole tool 228 may couple to the canister 226 with an interlocking latch, such that rotation (or linear movement or electric or hydraulic switches) of the downhole tool 228 may latch to (or unlatch from) the canister 226. In alternative aspects, the downhole tool 224 may include one or more magnets (e.g., rare Earth magnets, electromagnets, a combination thereof, or otherwise) which attractingly couple to the canister 226. In some examples, the canister 226 may also include one or more magnets (e.g., rare Earth magnets, electromagnets, a combination thereof, or otherwise) of an opposite polarity as the magnets on the downhole tool 224. In some examples, the canister 226 may be made from or include a ferrous or other material attractable to the magnets of the downhole tool 224. As another example, each canister 226 may be positioned within the drillhole 204 by a drillhole tractor (e.g., on a wireline or otherwise), which may push or pull the canister into the substantially horizontal portion 210 through motorized (e.g., electric) motion. As yet another example, each canister 226 may include or be mounted to rollers (e.g., wheels), so that the downhole tool 224 may push the canister 226 into the cased drillhole 204. In some example implementations, the canister 226, one or more of the drillhole casings 220 and 222, or both, may be coated with a friction-reducing coating prior to the deposit operation. For example, by applying a coating (e.g., petroleum-based product, resin, ceramic, or otherwise) to the canister 226 and/or drillhole casings, the canister 226 may be more easily moved through the cased drillhole 204 into the substantially horizontal portion 210. In some aspects, only a portion of the drillhole casings may be coated. For example, in some aspects, the substantially vertical portion 206 may not be coated, but the J-section portion 208 or the substantially horizontal portion 210, or both, may be coated to facilitate easier deposit and retrieval of the canister 226. FIG. 2 also illustrates an example of a retrieval operation of hazardous material in the substantially horizontal portion 210 of the drillhole 204. A retrieval operation may be the opposite of a deposit operation, such that the downhole tool 224 (e.g., a fishing tool) may be run into the drillhole 204, coupled to the last-deposited canister 226 (e.g., threadingly, latched, by magnet, or otherwise), and pull the canister 226 to the terranean surface 202. Multiple retrieval trips may be made by the downhole tool 224 in order to retrieve multiple canisters from the substantially horizontal portion 210 of the drillhole 204. Each canister 226 may enclose hazardous material. Such hazardous material, in some examples, may be biological or chemical waste or other biological or chemical hazardous material. In some examples, the hazardous material may include nuclear material, such as spent nuclear fuel recovered from a nuclear reactor (e.g., commercial power or test reactor) or military nuclear material. For example, a gigawatt nuclear plant may produce 30 tons of spent nuclear fuel per year. The density of that fuel is typically close to 10 (10 gm/cm3=10 kg/liter), so that the volume for a year of nuclear waste is about 3 m3. Spent nuclear fuel, in the form of nuclear fuel pellets, may be taken from the reactor and not modified. Nuclear fuel pellet are solid, although they can contain and emit a variety of radioactive gases including tritium (13 year half-life), krypton-85 (10.8 year half-life), and carbon dioxide containing C-14 (5730 year half-life). In some aspects, the storage layer 219 should be able to contain any radioactive output (e.g., gases) within the layer 219, even if such output escapes the canisters 226. For example, the storage layer 219 may be selected based on diffusion times of radioactive output through the layer 219. For example, a minimum diffusion time of radioactive output escaping the storage layer 219 may be set at, for example, fifty times a half-life for any particular component of the nuclear fuel pellets. Fifty half-lives as a minimum diffusion time would reduce an amount of radioactive output by a factor of 1×10−15. As another example, setting a minimum diffusion time to thirty half-lives would reduce an amount of radioactive output by a factor of one billion. For example, plutonium-239 is often considered a dangerous waste product in spent nuclear fuel because of its long half-life of 24,100 years. For this isotope, 50 half-lives would be 1.2 million years. Plutonium-239 has low solubility in water, is not volatile, and as a solid is not capable of diffusion through a matrix of the rock formation that comprises the illustrated storage layer 219 (e.g., shale or other formation). The storage layer 219, for example comprised of shale, may offer the capability to have such isolation times (e.g., millions of years) as shown by the geological history of containing gaseous hydrocarbons (e.g., methane and otherwise) for several million years. In contrast, in conventional nuclear material storage methods, there was a danger that some plutonium might dissolve in a layer that comprised mobile ground water upon confinement escape. As further shown in FIG. 2, the storage canisters 226 may be positioned for long term storage in the substantially horizontal portion 210, which, as shown, is coupled to the vertical portion 106 of the drillhole 104 through the J-section portion 208. As illustrated, the J-section portion 208 includes an upwardly directed portion angled toward the terranean surface 202. In some aspects, for example when there is radioactive hazardous material stored in the canisters 226, this inclination of the J-section portion 208 (and inclination of the inclined portion 240, if formed) may provide a further degree of safety and containment to prevent or impede the material, even if leaked from the canister 226, from reaching, e.g., the mobile water layer 214, the vertical portion 206 of the drillhole 204, the terranean surface 202, or a combination thereof. For example, radionuclides of concern in the hazardous material tend to be relatively buoyant or heavy (as compared to other components of the material). Buoyant radionuclides may be the greatest concern for leakage, since heavy elements and molecules tend to sink, and would not diffuse upward towards the terranean surface 202. Krypton gas, and particularly krypton-85, is a buoyant radioactive element that is heavier than air (as are most gases) but much lighter than water. Thus, should krypton-85 be introduced into a water bath, such gas would tend to float upward towards the terranean surface 202. Iodine, on the other hand, is denser than water, and would tend to diffuse downward if introduced into a water bath. By including the J-section portion 208 of the drillhole 204, any such diffusion of radioactive material (e.g., even if leaked from a canister 226 and in the presence of water or other liquid in the drillhole 204 or otherwise) would be directed angularly upward toward the substantially horizontal portion 210, and more specifically, toward a distal end 221 of the substantially horizontal portion 210 and away from the J-section portion 208 (and the vertical portion 206) of the drillhole 204. Thus, leaked hazardous material, even in a diffusible gas form, would not be offered a path (e.g., directly) to the terranean surface 202 (or the mobile water layer 214) through the vertical portion 206 of the drillhole 210. For instance, the leaked hazardous material (especially in gaseous form) would be directed and gathered at the distal end 221 of the drillhole portion 210, or, generally, within the substantially horizontal portion 210 of the drillhole 204. Alternative methods of depositing the canisters 226 into the inclined drillhole portion 210 may also be implemented. For instance, a fluid (e.g., liquid or gas) may be circulated through the drillhole 204 to fluidly push the canisters 226 into the inclined drillhole portion 210. In some example, each canister 226 may be fluidly pushed separately. In alternative aspects, two or more canisters 226 may be fluidly pushed, simultaneously, through the drillhole 204 for deposit into the substantially horizontal portion 210. The fluid can be, in some cases, water. Other examples include a drilling mud or drilling foam. In some examples, a gas may be used to push the canisters 226 into the drillhole, such as air, argon, or nitrogen. In some aspects, the choice of fluid may depend at least in part on a viscosity of the fluid. For example, a fluid may be chosen with enough viscosity to impede the drop of the canister 226 into the substantially vertical portion 206. This resistance or impedance may provide a safety factor against a sudden drop of the canister 226. The fluid may also provide lubrication to reduce a sliding friction between the canister 226 and the casings 220 and 222. The canister 226 can be conveyed within a casing filled with a liquid of controlled viscosity, density, and lubricant qualities. The fluid-filled annulus between the inner diameter of the casings 220 and 222 and the outer diameter of the conveyed canister 226 represents an opening designed to dampen any high rate of canister motion, providing automatic passive protection in an unlikely decoupling of the conveyed canister 226. In some aspects, other techniques may be employed to facilitate deposit of the canister 226 into the substantially horizontal portion 210. For example, one or more of the installed casings (e.g., casings 220 and 222) may have rails to guide the storage canister 226 into the drillhole 202 while reducing friction between the casings and the canister 226. The storage canister 226 and the casings (or the rails) may be made of materials that slide easily against one another. The casings may have a surface that is easily lubricated, or one that is self-lubricating when subjected to the weight of the storage canister 226. The fluid may also be used for retrieval of the canister 226. For example, in an example retrieval operation, a volume within the casings 220 and 222 may be filled with a compressed gas (e.g., air, nitrogen, argon, or otherwise). As the pressure increases at an end of the substantially horizontal portion 210, the canisters 226 may be pushed toward the J-section portion 208, and subsequently through the substantially vertical portion 206 to the terranean surface. In some aspects, the drillhole 204 may be formed for the primary purpose of long-term storage of hazardous materials. In alternative aspects, the drillhole 204 may have been previously formed for the primary purpose of hydrocarbon production (e.g., oil, gas). For example, storage layer 219 may be a hydrocarbon bearing formation from which hydrocarbons were produced into the drillhole 204 and to the terranean surface 202. In some aspects, the storage layer 219 may have been hydraulically fractured prior to hydrocarbon production. Further in some aspects, the production casing 222 may have been perforated prior to hydraulic fracturing. In such aspects, the production casing 222 may be patched (e.g., cemented) to repair any holes made from the perforating process prior to a deposit operation of hazardous material. In addition, any cracks or openings in the cement between the casing and the drillhole can also be filled at that time. For example, in the case of spent nuclear fuel as a hazardous material, the drillhole may be formed at a particular location, e.g., near a nuclear power plant, as a new drillhole provided that the location also includes an appropriate storage layer 219, such as a shale formation. Alternatively, an existing well that has already produced shale gas, or one that was abandoned as “dry,” (e.g., with sufficiently low organics that the gas in place is too low for commercial development), may be selected as the drillhole 204. In some aspects, prior hydraulic fracturing of the storage layer 219 through the drillhole 204 may make little difference in the hazardous material storage capability of the drillhole 204. But such a prior activity may also confirm the ability of the storage layer 219 to store gases and other fluids for millions of years. If, therefore, the hazardous material or output of the hazardous material (e.g., radioactive gasses or otherwise) were to escape from the canister 226 and enter the fractured formation of the storage layer 219, such fractures may allow that material to spread relatively rapidly over a distance comparable in size to that of the fractures. In some aspects, the drillhole 202 may have been drilled for a production of hydrocarbons, but production of such hydrocarbons had failed, e.g., because the storage layer 219 comprised a rock formation (e.g., shale or otherwise) that was too ductile and difficult to fracture for production, but was advantageously ductile for the long-term storage of hazardous material. FIG. 3 is a schematic illustration of example implementations of another hazardous material storage repository system, e.g., a subterranean location for the long-term (e.g., tens, hundreds, or thousands of years or more) but retrievable safe and secure storage of hazardous material, during a deposit or retrieval operation according to the present disclosure. For example, turning to FIG. 3, this figure illustrates an example hazardous material storage repository system 300 during a deposit (or retrieval, as described below) process, e.g., during deployment of one or more canisters of hazardous material in a subterranean formation. As illustrated, the hazardous material storage repository system 300 includes a drillhole 304 formed (e.g., drilled or otherwise) from a terranean surface 302 and through multiple subterranean layers 312, 314, and 316. Although the terranean surface 302 is illustrated as a land surface, terranean surface 302 may be a sub-sea or other underwater surface, such as a lake or an ocean floor or other surface under a body of water. Thus, the present disclosure contemplates that the drillhole 304 may be formed under a body of water from a drilling location on or proximate the body of water. The illustrated drillhole 304 is a directional drillhole in this example of hazardous material storage repository system 300. For instance, the drillhole 304 includes a substantially vertical portion 306 coupled to a curved portion 308, which in turn is coupled to a vertically undulating portion 310. As used in the present disclosure, “substantially” in the context of a drillhole orientation, refers to drillholes that may not be exactly vertical (e.g., exactly perpendicular to the terranean surface 302) or exactly horizontal (e.g., exactly parallel to the terranean surface 302), or exactly inclined at a particular incline angle relative to the terranean surface 302. In other words, vertical drillholes often undulate offset from a true vertical direction, that they might be drilled at an angle that deviates from true vertical, and horizontal drillholes often undulate offset from exactly horizontal. Further, in some aspects, an undulating portion may not undulate with regularity, i.e., have peaks that are uniformly spaced apart or valleys that are uniformly spaced apart. Instead, an undulating drillhole may undulate irregularly, e.g., with peaks that are non-uniformly spaced and/or valleys that are non-uniformly spaced. Further, an undulated drillhole may have a peak-to-valley distance that varies along a length of the drillhole. As illustrated in this example, the three portions of the drillhole 304—the vertical portion 306, the curved portion 308, and the vertically undulating portion 310—form a continuous drillhole 304 that extends into the Earth. The illustrated drillhole 304, in this example, has a surface casing 320 positioned and set around the drillhole 304 from the terranean surface 302 into a particular depth in the Earth. For example, the surface casing 320 may be a relatively large-diameter tubular member (or string of members) set (e.g., cemented) around the drillhole 304 in a shallow formation. As used herein, “tubular” may refer to a member that has a circular cross-section, elliptical cross-section, or other shaped cross-section. For example, in this implementation of the hazardous material storage repository system 300, the surface casing 320 extends from the terranean surface through a surface layer 312. The surface layer 312, in this example, is a geologic layer comprised of one or more layered rock formations. In some aspects, the surface layer 312 in this example may or may not include freshwater aquifers, salt water or brine sources, or other sources of mobile water (e.g., water that moves through a geologic formation). In some aspects, the surface casing 320 may isolate the drillhole 304 from such mobile water, and may also provide a hanging location for other casing strings to be installed in the drillhole 304. Further, although not shown, a conductor casing may be set above the surface casing 320 (e.g., between the surface casing 320 and the surface 302 and within the surface layer 312) to prevent drilling fluids from escaping into the surface layer 312. As illustrated, a production casing 322 is positioned and set within the drillhole 304 downhole of the surface casing 320. Although termed a “production” casing, in this example, the casing 322 may or may not have been subject to hydrocarbon production operations. Thus, the casing 322 refers to and includes any form of tubular member that is set (e.g., cemented) in the drillhole 304 downhole of the surface casing 320. In some examples of the hazardous material storage repository system 300, the production casing 322 may begin at an end of the curved portion 308 and extend throughout the vertically undulating portion 310. The casing 322 could also extend into the curved portion 308 and into the vertical portion 306. As shown, cement 330 is positioned (e.g., pumped) around the casings 320 and 322 in an annulus between the casings 320 and 322 and the drillhole 304. The cement 330, for example, may secure the casings 320 and 322 (and any other casings or liners of the drillhole 304) through the subterranean layers under the terranean surface 302. In some aspects, the cement 330 may be installed along the entire length of the casings (e.g., casings 320 and 322 and any other casings), or the cement 330 could be used along certain portions of the casings if adequate for a particular drillhole 302. The cement 330 can also provide an additional layer of confinement for the hazardous material in canisters 326. The drillhole 304 and associated casings 320 and 322 may be formed with various example dimensions and at various example depths (e.g., true vertical depth, or TVD). For instance, a conductor casing (not shown) may extend down to about 120 feet TVD, with a diameter of between about 28 in. and 60 in. The surface casing 320 may extend down to about 2500 feet TVD, with a diameter of between about 22 in. and 48 in. An intermediate casing (not shown) between the surface casing 320 and production casing 322 may extend down to about 8000 feet TVD, with a diameter of between about 16 in. and 36 in. The production casing 322 may extend inclinedly (e.g., to case the vertically undulating portion 310) with a diameter of between about 11 in. and 22 in. The foregoing dimensions are merely provided as examples and other dimensions (e.g., diameters, TVDs, lengths) are contemplated by the present disclosure. For example, diameters and TVDs may depend on the particular geological composition of one or more of the multiple subterranean layers (312, 314, and 316), particular drilling techniques, as well as a size, shape, or design of a hazardous material canister 326 that contains hazardous material to be deposited in the hazardous material storage repository system 300. In some alternative examples, the production casing 322 (or other casing in the drillhole 304) could be circular in cross-section, elliptical in cross-section, or some other shape. As illustrated, the vertical portion 306 of the drillhole 304 extends through subterranean layers 312, 314, and 316, and, in this example, lands in a subterranean layer 319. As discussed above, the surface layer 312 may or may not include mobile water. Subterranean layer 314, which is below the surface layer 312, in this example, is a mobile water layer 314. For instance, mobile water layer 314 may include one or more sources of mobile water, such as freshwater aquifers, salt water or brine, or other source of mobile water. In this example of hazardous material storage repository system 300, mobile water may be water that moves through a subterranean layer based on a pressure differential across all or a part of the subterranean layer. For example, the mobile water layer 314 may be a permeable geologic formation in which water freely moves (e.g., due to pressure differences or otherwise) within the layer 314. In some aspects, the mobile water layer 314 may be a primary source of human-consumable water in a particular geographic area. Examples of rock formations of which the mobile water layer 314 may be composed include porous sandstones and limestones, among other formations. Other illustrated layers, such as the impermeable layer 316 and the storage layer 319, may include immobile water. Immobile water, in some aspects, is water (e.g., fresh, salt, brine), that is not fit for human or animal consumption, or both. Immobile water, in some aspects, may be water that, by its motion through the layers 316 or 319 (or both), cannot reach the mobile water layer 314, terranean surface 302, or both, within 10,000 years or more (such as to 1,000,000 years). Below the mobile water layer 314, in this example implementation of hazardous material storage repository system 300, is an impermeable layer 316. The impermeable layer 316, in this example, may not allow mobile water to pass through. Thus, relative to the mobile water layer 314, the impermeable layer 316 may have low permeability, e.g., on the order of nanodarcy permeability. Additionally, in this example, the impermeable layer 316 may be a relatively non-ductile (i.e., brittle) geologic formation. One measure of non-ductility is brittleness, which is the ratio of compressive stress to tensile strength. In some examples, the brittleness of the impermeable layer 316 may be between about 20 MPa and 40 MPa. As shown in this example, the impermeable layer 316 is shallower (e.g., closer to the terranean surface 302) than the storage layer 319. In this example rock formations of which the impermeable layer 316 may be composed include, for example, certain kinds of sandstone, mudstone, clay, and slate that exhibit permeability and brittleness properties as described above. In alternative examples, the impermeable layer 316 may be deeper (e.g., further from the terranean surface 302) than the storage layer 319. In such alternative examples, the impermeable layer 316 may be composed of an igneous rock, such as granite. Below the impermeable layer 316 is the storage layer 319. The storage layer 319, in this example, may be chosen as the landing for the vertically undulating portion 310, which stores the hazardous material, for several reasons. Relative to the impermeable layer 316 or other layers, the storage layer 319 may be thick, e.g., between about 100 and 200 feet of total vertical thickness. Thickness of the storage layer 319 may allow for easier landing and directional drilling, thereby allowing the vertically undulating portion 310 to be readily emplaced within the storage layer 319 during constructions (e.g., drilling). If formed through an approximate horizontal center of the storage layer 319, the vertically undulating portion 310 may be surrounded by about 50 to 100 feet of the geologic formation that comprises the storage layer 319. Further, the storage layer 319 may also have only immobile water, e.g., due to a very low permeability of the layer 319 (e.g., on the order of milli- or nanodarcys). In addition, the storage layer 319 may have sufficient ductility, such that a brittleness of the rock formation that comprises the layer 319 is between about 3 MPa and 10 MPa. Examples of rock formations of which the storage layer 319 may be composed include: shale and anhydrite. Further, in some aspects, hazardous material may be stored below the storage layer, even in a permeable formation such as sandstone or limestone, if the storage layer is of sufficient geologic properties to isolate the permeable layer from the mobile water layer 314. In some examples implementations of the hazardous material storage repository system 300, the storage layer 319 (and/or the impermeable layer 316) is composed of shale. Shale, in some examples, may have properties that fit within those described above for the storage layer 319. For example, shale formations may be suitable for a long-term confinement of hazardous material (e.g., in the hazardous material canisters 326), and for their isolation from mobile water layer 314 (e.g., aquifers) and the terranean surface 302. Shale formations may be found relatively deep in the Earth, typically 3000 feet or greater, and placed in isolation below any fresh water aquifers. Other formations may include salt or other impermeable formation layer. Shale formations (or salt or other impermeable formation layers), for instance, may include geologic properties that enhance the long-term (e.g., thousands of years) isolation of material. Such properties, for instance, have been illustrated through the long term storage (e.g., tens of millions of years) of hydrocarbon fluids (e.g., gas, liquid, mixed phase fluid) without escape of such fluids into surrounding layers (e.g., mobile water layer 314). Indeed, shale has been shown to hold natural gas for millions of years or more, giving it a proven capability for long-term storage of hazardous material. Example shale formations (e.g., Marcellus, Eagle Ford, Barnett, and otherwise) has stratification that contains many redundant sealing layers that have been effective in preventing movement of water, oil, and gas for millions of years, lacks mobile water, and can be expected (e.g., based on geological considerations) to seal hazardous material (e.g., fluids or solids) for thousands of years after deposit. In some aspects, the formation of the storage layer 319 and/or the impermeable layer 316 may form a leakage barrier, or barrier layer to fluid leakage that may be determined, at least in part, by the evidence of the storage capacity of the layer for hydrocarbons or other fluids (e.g., carbon dioxide) for hundreds of years, thousands of years, tens of thousands of years, hundreds of thousands of years, or even millions of years. For example, the barrier layer of the storage layer 319 and/or impermeable layer 316 may be defined by a time constant for leakage of the hazardous material more than 10,000 years (such as between 10,000 years and 1,000,000 years) based on such evidence of hydrocarbon or other fluid storage. Shale (or salt or other impermeable layer) formations may also be at a suitable depth, e.g., between 3000 and 12,000 feet TVD. Such depths are typically below ground water aquifer (e.g., surface layer 312 and/or mobile water layer 314). Further, the presence of soluble elements in shale, including salt, and the absence of these same elements in aquifer layers, demonstrates a fluid isolation between shale and the aquifer layers. Another particular quality of shale that may advantageously lend itself to hazardous material storage is its clay content, which, in some aspects, provides a measure of ductility greater than that found in other, impermeable rock formations (e.g., impermeable layer 316). For example, shale may be stratified, made up of thinly alternating layers of clays (e.g., between about 20-30% clay by volume) and other minerals. Such a composition may make shale less brittle and, thus less susceptible to fracturing (e.g., naturally or otherwise) as compared to rock formations in the impermeable layer (e.g., dolomite or otherwise). For example, rock formations in the impermeable layer 316 may have suitable permeability for the long term storage of hazardous material, but are too brittle and commonly are fractured. Thus, such formations may not have sufficient sealing qualities (as evidenced through their geologic properties) for the long term storage of hazardous material. The present disclosure contemplates that there may be many other layers between or among the illustrated subterranean layers 312, 314, 316, and 319. For example, there may be repeating patterns (e.g., vertically), of one or more of the mobile water layer 314, impermeable layer 316, and storage layer 319. Further, in some instances, the storage layer 319 may be directly adjacent (e.g., vertically) the mobile water layer 314, i.e., without an intervening impermeable layer 316. In some examples, all or portions of the curved portion 308 and the vertically undulating portion 310 may be formed below the storage layer 319, such that the storage layer 319 (e.g., shale or other geologic formation with characteristics as described herein) is vertically positioned between the vertically undulating portion 310 and the mobile water layer 314. Although not illustrated in this particular example shown in FIG. 3, a self-healing layer (e.g., such as the self-healing layer 132) may be found below the terranean surface 302 and between, for example, the surface 302 and one or both of the impermeable layer 316 and the storage layer 319. In some aspects, the self-healing layer may comprise a geologic formation that can stop or impede a flow of hazardous material (whether in liquid, solid, or gaseous form) from a storage portion of the drillhole 304 to or toward the terranean surface 302. For example, during formation of the drillhole 304 (e.g., drilling), all are portions of the geologic formations of the layers 312, 314, 316, and 319, may be damaged, thereby affecting or changing their geologic characteristics (e.g., permeability). In certain aspects, the location of the drillhole 304 may be selected so as to be formed through the self-healing layer. For example, as shown, the drillhole 304 may be formed such that at least a portion of the vertical portion 306 of the drillhole 304 is formed to pass through the self-healing layer. In some aspects, the self-healing layer comprises a geologic formation that that does not sustain cracks for extended time durations even after being drilled therethrough. Examples of the geologic formation in the self-healing layer include clay or dolomite. Cracks in such rock formations tend to heal, that is, they disappear rapidly with time due to the relative ductility of the material, and the enormous pressures that occur underground from the weight of the overlying rock on the formation in the self-healing layer. In addition to providing a “healing mechanism” for cracks that occur due to the formation of the drillhole 304 (e.g., drilling or otherwise), the self-healing layer may also provide a barrier to natural faults and other cracks that otherwise could provide a pathway for hazardous material leakage (e.g., fluid or solid) from the storage region (e.g., in the vertically undulating portion 310) to the terranean surface 302, the mobile water layer 314, or both. As shown in this example, the vertically undulating portion 310 of the drillhole 304 includes a storage area 317 in a distal part of the portion 310 into which hazardous material may be retrievably placed for long-term storage. For example, as shown, a work string 324 (e.g., tubing, coiled tubing, wireline, or otherwise) may be extended into the cased drillhole 304 to place one or more (three shown but there may be more or less) hazardous material canisters 326 into long term, but in some aspects, retrievable, storage in the portion 310. For example, in the implementation shown in FIG. 3, the work string 324 may include a downhole tool 328 that couples to the canister 326, and with each trip into the drillhole 304, the downhole tool 328 may deposit a particular hazardous material canister 326 in the vertically undulating portion 310. The downhole tool 328 may couple to the canister 326 by, in some aspects, a threaded connection or other type of connection, such as a latched connection. In alternative aspects, the downhole tool 328 may couple to the canister 326 with an interlocking latch, such that rotation (or linear movement or electric or hydraulic switches) of the downhole tool 328 may latch to (or unlatch from) the canister 326. In alternative aspects, the downhole tool 324 may include one or more magnets (e.g., rare Earth magnets, electromagnets, a combination thereof, or otherwise) which attractingly couple to the canister 326. In some examples, the canister 326 may also include one or more magnets (e.g., rare Earth magnets, electromagnets, a combination thereof, or otherwise) of an opposite polarity as the magnets on the downhole tool 324. In some examples, the canister 326 may be made from or include a ferrous or other material attractable to the magnets of the downhole tool 324. As another example, each canister 326 may be positioned within the drillhole 304 by a drillhole tractor (e.g., on a wireline or otherwise), which may push or pull the canister into the vertically undulating portion 310 through motorized (e.g., electric) motion. As yet another example, each canister 326 may include or be mounted to rollers (e.g., wheels), so that the downhole tool 324 may push the canister 326 into the cased drillhole 304. In some example implementations, the canister 326, one or more of the drillhole casings 320 and 322, or both, may be coated with a friction-reducing coating prior to the deposit operation. For example, by applying a coating (e.g., petroleum-based product, resin, ceramic, or otherwise) to the canister 326 and/or drillhole casings, the canister 326 may be more easily moved through the cased drillhole 304 into the vertically undulating portion 310. In some aspects, only a portion of the drillhole casings may be coated. For example, in some aspects, the substantially vertical portion 306 may not be coated, but the curved portion 308 or the vertically undulating portion 310, or both, may be coated to facilitate easier deposit and retrieval of the canister 326. FIG. 3 also illustrates an example of a retrieval operation of hazardous material in the vertically undulating portion 310 of the drillhole 304. A retrieval operation may be the opposite of a deposit operation, such that the downhole tool 324 (e.g., a fishing tool) may be run into the drillhole 304, coupled to the last-deposited canister 326 (e.g., threadingly, latched, by magnet, or otherwise), and pull the canister 326 to the terranean surface 302. Multiple retrieval trips may be made by the downhole tool 324 in order to retrieve multiple canisters from the vertically undulating portion 310 of the drillhole 304. Each canister 326 may enclose hazardous material. Such hazardous material, in some examples, may be biological or chemical waste or other biological or chemical hazardous material. In some examples, the hazardous material may include nuclear material, such as spent nuclear fuel recovered from a nuclear reactor (e.g., commercial power or test reactor) or military nuclear material. For example, a gigawatt nuclear plant may produce 30 tons of spent nuclear fuel per year. The density of that fuel is typically close to 10 (10 gm/cm3=10 kg/liter), so that the volume for a year of nuclear waste is about 3 m3. Spent nuclear fuel, in the form of nuclear fuel pellets, may be taken from the reactor and not modified. Nuclear fuel pellet are solid, although they can contain and emit a variety of radioactive gases including tritium (13 year half-life), krypton-85 (10.8 year half-life), and carbon dioxide containing C-14 (5730 year half-life). In some aspects, the storage layer 319 should be able to contain any radioactive output (e.g., gases) within the layer 319, even if such output escapes the canisters 326. For example, the storage layer 319 may be selected based on diffusion times of radioactive output through the layer 319. For example, a minimum diffusion time of radioactive output escaping the storage layer 319 may be set at, for example, fifty times a half-life for any particular component of the nuclear fuel pellets. Fifty half-lives as a minimum diffusion time would reduce an amount of radioactive output by a factor of 1×10−15. As another example, setting a minimum diffusion time to thirty half-lives would reduce an amount of radioactive output by a factor of one billion. For example, plutonium-239 is often considered a dangerous waste product in spent nuclear fuel because of its long half-life of 24,100 years. For this isotope, 50 half-lives would be 1.2 million years. Plutonium-239 has low solubility in water, is not volatile, and as a solid is not capable of diffusion through a matrix of the rock formation that comprises the illustrated storage layer 319 (e.g., shale or other formation). The storage layer 319, for example comprised of shale, may offer the capability to have such isolation times (e.g., millions of years) as shown by the geological history of containing gaseous hydrocarbons (e.g., methane and otherwise) for several million years. In contrast, in conventional nuclear material storage methods, there was a danger that some plutonium might dissolve in a layer that comprised mobile ground water upon confinement escape. As further shown in FIG. 3, the storage canisters 326 may be positioned for long term storage in the vertically undulating portion 310, which, as shown, is coupled to the vertical portion 106 of the drillhole 104 through the curved portion 308. As illustrated, the curved portion 308 includes an upwardly directed portion angled toward the terranean surface 302. Further, as shown, the undulating portion 310 of the drillhole 304 includes several upwardly and downwardly (relative to the surface 302) inclined portions, thereby forming several peaks and valleys in the undulating portion 310. In some aspects, for example when there is radioactive hazardous material stored in the canisters 326, these inclinations of the curved portion 308 and undulating portion 310 may provide a further degree of safety and containment to prevent or impede the material, even if leaked from the canister 326, from reaching, e.g., the mobile water layer 314, the vertical portion 306 of the drillhole 304, the terranean surface 302, or a combination thereof. For example, radionuclides of concern in the hazardous material tend to be relatively buoyant or heavy (as compared to other components of the material). Buoyant radionuclides may be the greatest concern for leakage, since heavy elements and molecules tend to sink, and would not diffuse upward towards the terranean surface 302. Krypton gas, and particularly krypton-85, is a buoyant radioactive element that is heavier than air (as are most gases) but much lighter than water. Thus, should krypton-85 be introduced into a water bath, such gas would tend to float upward towards the terranean surface 302. Iodine, on the other hand, is denser than water, and would tend to diffuse downward if introduced into a water bath. By including the curved portion 308 of the drillhole 304 and the undulating portion 310, any such diffusion of radioactive material (e.g., even if leaked from a canister 326 and in the presence of water or other liquid in the drillhole 304 or otherwise) would be directed toward the vertically undulating portion 310, and more specifically, to peaks within the vertically undulating portion 310 and away from the curved portion 308 (and the vertical portion 306) of the drillhole 304. Thus, leaked hazardous material, even in a diffusible gas form, would not be offered a path (e.g., directly) to the terranean surface 302 (or the mobile water layer 314) through the vertical portion 306 of the drillhole 310. For instance, the leaked hazardous material (especially in gaseous form) would be directed and gathered at the peaks of the drillhole portion 310, or, generally, within the vertically undulating portion 310 of the drillhole 304. Alternative methods of depositing the canisters 326 into the inclined drillhole portion 310 may also be implemented. For instance, a fluid (e.g., liquid or gas) may be circulated through the drillhole 304 to fluidly push the canisters 326 into the inclined drillhole portion 310. In some example, each canister 326 may be fluidly pushed separately. In alternative aspects, two or more canisters 326 may be fluidly pushed, simultaneously, through the drillhole 304 for deposit into the vertically undulating portion 310. The fluid can be, in some cases, water. Other examples include a drilling mud or drilling foam. In some examples, a gas may be used to push the canisters 326 into the drillhole, such as air, argon, or nitrogen. In some aspects, the choice of fluid may depend at least in part on a viscosity of the fluid. For example, a fluid may be chosen with enough viscosity to impede the drop of the canister 326 into the substantially vertical portion 306. This resistance or impedance may provide a safety factor against a sudden drop of the canister 326. The fluid may also provide lubrication to reduce a sliding friction between the canister 326 and the casings 320 and 322. The canister 326 can be conveyed within a casing filled with a liquid of controlled viscosity, density, and lubricant qualities. The fluid-filled annulus between the inner diameter of the casings 320 and 322 and the outer diameter of the conveyed canister 326 represents an opening designed to dampen any high rate of canister motion, providing automatic passive protection in an unlikely decoupling of the conveyed canister 326. In some aspects, other techniques may be employed to facilitate deposit of the canister 326 into the vertically undulating portion 310. For example, one or more of the installed casings (e.g., casings 320 and 322) may have rails to guide the storage canister 326 into the drillhole 302 while reducing friction between the casings and the canister 326. The storage canister 326 and the casings (or the rails) may be made of materials that slide easily against one another. The casings may have a surface that is easily lubricated, or one that is self-lubricating when subjected to the weight of the storage canister 326. The fluid may also be used for retrieval of the canister 326. For example, in an example retrieval operation, a volume within the casings 320 and 322 may be filled with a compressed gas (e.g., air, nitrogen, argon, or otherwise). As the pressure increases at an end of the vertically undulating portion 310, the canisters 326 may be pushed toward the curved portion 308, and subsequently through the substantially vertical portion 306 to the terranean surface. In some aspects, the drillhole 304 may be formed for the primary purpose of long-term storage of hazardous materials. In alternative aspects, the drillhole 304 may have been previously formed for the primary purpose of hydrocarbon production (e.g., oil, gas). For example, storage layer 319 may be a hydrocarbon bearing formation from which hydrocarbons were produced into the drillhole 304 and to the terranean surface 302. In some aspects, the storage layer 319 may have been hydraulically fractured prior to hydrocarbon production. Further in some aspects, the production casing 322 may have been perforated prior to hydraulic fracturing. In such aspects, the production casing 322 may be patched (e.g., cemented) to repair any holes made from the perforating process prior to a deposit operation of hazardous material. In addition, any cracks or openings in the cement between the casing and the drillhole can also be filled at that time. For example, in the case of spent nuclear fuel as a hazardous material, the drillhole may be formed at a particular location, e.g., near a nuclear power plant, as a new drillhole provided that the location also includes an appropriate storage layer 319, such as a shale formation. Alternatively, an existing well that has already produced shale gas, or one that was abandoned as “dry,” (e.g., with sufficiently low organics that the gas in place is too low for commercial development), may be selected as the drillhole 304. In some aspects, prior hydraulic fracturing of the storage layer 319 through the drillhole 304 may make little difference in the hazardous material storage capability of the drillhole 304. But such a prior activity may also confirm the ability of the storage layer 319 to store gases and other fluids for millions of years. If, therefore, the hazardous material or output of the hazardous material (e.g., radioactive gasses or otherwise) were to escape from the canister 326 and enter the fractured formation of the storage layer 319, such fractures may allow that material to spread relatively rapidly over a distance comparable in size to that of the fractures. In some aspects, the drillhole 302 may have been drilled for a production of hydrocarbons, but production of such hydrocarbons had failed, e.g., because the storage layer 319 comprised a rock formation (e.g., shale or otherwise) that was too ductile and difficult to fracture for production, but was advantageously ductile for the long-term storage of hazardous material. FIG. 4A-4C are schematic illustrations of other example implementations of a hazardous material storage repository system according to the present disclosure. FIG. 4A shows hazardous material storage repository system 400, FIG. 4B shows hazardous material storage repository system 450, and FIG. 4C shows hazardous material storage repository system 480. Each of the systems 400, 450, and 480 include a substantially vertical drillhole (404, 454, and 484, respectively) drilled from a terranean surface (402, 452, and 482, respectively). Each substantially vertical drillhole (404, 454, 484) couples to (or continues into) a transition drillhole (406, 456, and 486, respectively) that is a curved or radiussed drillhole. Each transition drillhole (406, 456, and 486) then couples to (or continues into) an isolation drillhole (408, 458, and 488, respectively) that includes or comprises a hazardous material storage repository into which one or more hazardous material storage canisters (e.g., canisters 126) may be placed for long-term storage and, if necessary retrieved according to the present disclosure. As shown in FIG. 4A, the isolation drillhole 408 is a spiral drillhole that, at the point where it connects to the transition drillhole 406, starts to curve to the horizontal and simultaneously begins to curve to the side, i.e. in a horizontal direction. Once the spiral drillhole reaches its lowest point, it continues to curve in both directions, giving it a slight upward spiral. At that point the horizontal curve may be made a little bigger so that the curve does not intersect the vertical drillhole 404. Once the spiral drillhole begins to rise, a curved hazardous material storage repository section may commence. The storage section may continue until a highest point (e.g., point closest to the terranean surface 402), which is a dead-end trap (e.g., for escaped hazardous material solid, liquid, or gas). The rise of the spiral drillhole can be typically 3 degrees. In some aspects, the path of the spiral drillhole 408 can be down the axis of the spiral (that is, in the center of the spiraling circles) or displaced. Also, as shown in FIG. 4A, the vertical drillhole 404 is formed within the spiral drillhole 408. In other words, the spiral drillhole 408 may be formed symmetrically around the vertical drillhole 404. Turning briefly to FIG. 4C, the system 480 shows a spiral drillhole 488 similar to that of the spiral drillhole 408. However, spiral drillhole 488 is formed offset and to a side of the vertical drillhole 484. In some aspects, the spiral drillhole 488 can be formed offset of any side of the vertical drillhole 484. Turning to FIG. 4B, the system 450 includes a spiral drillhole 458 that is coupled to the transition drillhole 456 that turns from the vertical drillhole 454. Here, the spiral drillhole 458, rather than being oriented vertically (e.g., with an axis of rotation parallel of the vertical drillhole), is oriented horizontally (e.g., with an axis of rotation perpendicular to the vertical drillhole 454). At an end of or within the spiral drillhole 458 (or both) is a hazardous material storage section. In the implementations of systems 400, 450, and 480, a radius of curvature of the transition drillholes may be about 1000 feet. The circumference of each spiral in the spiral drillholes may be about 227 times the radius of curvature, or about 6,000 feet. Thus, each spiral in the spiral drillholes may contain a bit over one mile of storage area of hazardous material canisters. In some alternative aspects, the radius of curvature may be about 500 feet. Then, each spiral of the spiral drillholes may include about 0.5 miles of storage area of hazardous material canisters. If two miles of storage is desired then there may be four spirals for each spiral drillholes of this size. As shown in FIGS. 4A-4C, each of the systems 400, 450, and 480 include drillhole portions that serve as hazardous material storage areas and are directed vertically toward the terranean surface and away from an intersection between the transition drillhole of each system and the vertical drillhole of each section. Thus, any leaked hazardous material (e.g., such as radioactive waste gas) may be directed to such vertically-directed storage areas and away from the vertical drillholes. Each of the drillholes shown in FIGS. 4A-4C may be cased or uncased; the casing may serve as an additional layer of protection to prevent hazardous material from reaching mobile water. If casing is omitted, then angular changes to any drillhole can be more rapid with a constraint being the accommodation of movement of any canister therethrough. If there is casing, angular changes in direction for the drillholes may be done sufficiently slowly (as they are in standard directional drilling) that the casing can be pushed into the drillhole. Further, in some aspects, all or a portion of each of the illustrated isolation drillholes (408, 458, and 488) may be formed in or under an impermeable layer (as described in the present disclosure). In some aspects, implementations of a spiral drillhole may have a constant curvature around an axis of rotation. Alternative implementations of a spiral drillhole may have a gradually changing curvature, making the spirals in the spiral drillhole either tighter or less confined. Still additional implementations of a spiral drillhole may have the spirals changing in radius (making it tighter or less tight) but have little or no vertical rise (e.g., for situations in which it might be useful if the geologic layer in which the hazardous material storage section of the isolation drillholes is not very thick in the vertical dimension). FIG. 5A is a top view, and FIGS. 5B-5C are side views, of schematic illustrations of another example implementation of a hazardous material storage repository system 500. As shown, the system includes a vertical drillhole 504 formed from a terranean surface 502. The vertical drillhole 504 is coupled to or continues into a transition drillhole 506. The transition drillhole 506 is coupled to or turns into an isolation drillhole 508. In this example, the isolation drillhole 508 includes or comprise an undulating drillhole in which the undulations are substantially side-to-side. As shown in FIG. 5B, the isolation drillhole 508 rises toward the terranean surface 502 and vertically away from the transition drillhole 506 as it undulates side-to-side. As shown in FIG. 5C, alternatively, the isolation drillhole 508 stays in a plane substantially parallel to the terranean surface 502 as it undulates side-to-side. In some aspects, the spiral or undulating drillholes may be oriented without regard to the stress pattern of any gas or oil bearing layer in which they are formed. This is because the orientation need not take into account any fracturing of the drillhole as is the case for hydrocarbon production. Thus, drillhole geometers that are not oriented in the direction of the rock stress pattern, and are more compact, can be utilized. These drillholes may also have significant value in reducing the amount of terranean land under which the drillholes are formed. This may also reduce a cost of the land and of any mineral rights that must be bought to allow the hazardous material storage repository systems to be built. The drillholes are therefore determined not by the pattern of stresses in the rock, but primarily by the efficient and practical use of the available land. Each of the drillholes shown in FIGS. 5A-5C may be cased or uncased; the casing may serve as an additional layer of protection to prevent hazardous material from reaching mobile water. If casing is omitted, then angular changes to any drillhole can be more rapid with a constraint being the accommodation of movement of any canister therethrough. If there is casing, angular changes in direction for the drillholes may be done sufficiently slowly (as they are in standard directional drilling) that the casing can be pushed into the drillhole. Further, in some aspects, all or a portion of the isolation drillhole 508 may be formed in or under an impermeable layer (as described in the present disclosure). Referring generally to FIGS. 1A, 2, 3, 4A-4C, and 5A-5C, the example hazardous material storage repository systems (e.g., 100, 200, 300, 400, 450, 480, and 500) may provide for multiple layers of containment to ensure that a hazardous material (e.g., biological, chemical, nuclear) is sealingly stored in an appropriate subterranean layer. In some example implementations, there may be at least twelve layers of containment. In alternative implementations, a fewer or a greater number of containment layers may be employed. First, using spent nuclear fuel as an example hazardous material, the fuel pellets are taken from the reactor and not modified. They may be made from sintered uranium dioxide (UO2), a ceramic, and may remain solid and emit a variety of radioactive gases including tritium (13 year half-life), krypton-85 (10.8 year half-life), and carbon dioxide containing C-14 (5730 year half-life). Unless the pellets are exposed to extremely corrosive conditions or other effects that damage the multiple layers of containment, most of the radioisotopes (including the C-14, tritium or krypton-85) will be contained in the pellets. Second, the fuel pellets are surrounded by the zircaloy tubes of the fuel rods, just as in the reactor. As described, the tubes could be mounted in the original fuel assemblies, or removed from those assemblies for tighter packing. Third, the tubes are placed in the sealed housings of the hazardous material canister. The housing may be a unified structure or multi-panel structure, with the multiple panels (e.g., sides, top, bottom) mechanically fastened (e.g., screws, rivets, welds, and otherwise). Fourth, a material (e.g., solid or fluid) may fill the hazardous material canister to provide a further buffer between the material and the exterior of the canister. Fifth, the hazardous material canister(s) are positioned (as described above), in a drillhole that is lined with a steel or other sealing casing that extends, in some examples, throughout the entire drillhole (e.g., a substantially vertical portion, a radiussed portion, and a inclined portion). The casing is cemented in place, providing a relatively smooth surface (e.g., as compared to the drillhole wall) for the hazardous material canister to be moved through, thereby reducing the possibility of a leak or break during deposit or retrieval. Sixth, the cement that holds or helps hold the casing in place, may also provide a sealing layer to contain the hazardous material should it escape the canister. Seventh, the hazardous material canister is stored in a portion of the drillhole (e.g., the inclined portion) that is positioned within a thick (e.g., 100-200 feet) seam of a rock formation that comprises a storage layer. The storage layer may be chosen due at least in part to the geologic properties of the rock formation (e.g., only immobile water, low permeability, thick, appropriate ductility or non-brittleness). For example, in the case of shale as the rock formation of the storage layer, this type of rock may offers a level of containment since it is known that shale has been a seal for hydrocarbon gas for millions of years. The shale may contain brine, but that brine is demonstrably immobile, and not in communication with surface fresh water. Eighth, in some aspects, the rock formation of the storage layer may have other unique geological properties that offer another level of containment. For example, shale rock often contains reactive components, such as iron sulfide, that reduce the likelihood that hazardous materials (e.g., spent nuclear fuel and its radioactive output) can migrate through the storage layer without reacting in ways that reduce the diffusion rate of such output even further. Further, the storage layer may include components, such as clay and organic matter, that typically have extremely low diffusivity. For example, shale may be stratified and composed of thinly alternating layers of clays and other minerals. Such a stratification of a rock formation in the storage layer, such as shale, may offer this additional layer of containment. Ninth, the storage layer may be located deeper than, and under, an impermeable layer, which separates the storage layer (e.g., vertically) from a mobile water layer. Tenth, the storage layer may be selected based on a depth (e.g., 3000 to 12,000 ft.) of such a layer within the subterranean layers. Such depths are typically far below any layers that contain mobile water, and thus, the sheer depth of the storage layer provides an additional layer of containment. Eleventh, example implementations of the hazardous material storage repository system of the present disclosure facilitate monitoring of the stored hazardous material. For example, if monitored data indicates a leak or otherwise of the hazardous material (e.g., change in temperature, radioactivity, or otherwise), or even tampering or intrusion of the canister, the hazardous material canister may be retrieved for repair or inspection. Twelfth, the one or more hazardous material canisters may be retrievable for periodic inspection, conditioning, or repair, as necessary (e.g., with or without monitoring). Thus, any problem with the canisters may be addressed without allowing hazardous material to leak or escape from the canisters unabated. Thirteenth, even if hazardous material escaped from the canisters and no impermeable layer was located between the leaked hazardous material and the terranean surface, the leaked hazardous material may be contained within the drillhole at a location that has no upward path to the surface or to aquifers (e.g., mobile water layers) or to other zones that would be considered hazardous to humans. For example, the location, which may be a dead end of an inclined drillhole, a J-section drillhole, or peaks of a vertically undulating drillhole, may have no direct upward (e.g., toward the surface) path to a vertical portion of the drillhole. A number of implementations have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure. For example, example operations, methods, or processes described herein may include more steps or fewer steps than those described. Further, the steps in such example operations, methods, or processes may be performed in different successions than that described or illustrated in the figures. Accordingly, other implementations are within the scope of the following claims.
	abstract	A system and method for testing derating performance of a component obtains a component list, a pin list, and a standard derating list of the electronic device from a storage. The system and method further receives parameters of each component, the parameters of each component comprising voltages of two pins of the component and a working temperature of the component, calculates a working voltage and a derating ratio of the component according to the parameters. The system and method also analyzes the working voltage and the derating ratio of the component to get analysis result, generates a test report comprising the derating ratio, the working temperature, the analysis results of each component in the component list, and storing the test report in the storage.
	claims	1. A multi-leaf collimator comprising a plurality of leaves, each leaf being movable to allow a selected portion of radiation energy to be blocked, whereby a shape is defined by a portion of radiation energy which is incident at a target, and the shape is controlled by a positioning of the plurality of leaves,wherein at least some of the plurality of leaves comprise a leaf body which includes a first section and a second section, the first section being thicker than the second section and being provided with a drive screw adapted to move the leaf body. 2. The multi-leaf collimator of claim 1 wherein the drive screw is provided inside the first section of the leaf body. 3. The multi-leaf collimator of claim 1 whereinthe first section provides a first edge portion of the leaf body, the second section provides a second edge portion of the leaf body, andthe first edge portion of the leaf body is provided with an elongate recess adapted to slidably engage a support, the second edge portion of the leaf body is provided with an elongate step adapted to slidably engage the support. 4. The multi-leaf collimator of claim 1 wherein the first section of the leaf body has a cross-section in a trapezoidal shape. 5. The multi-leaf collimator of claim 1 wherein the at least some of plurality leaves are arranged such that a first section of a leaf body is adjacent to a second section of another leaf body. 6. The multi-leaf collimator of claim 1 wherein the plurality of leaves comprise a first set of leaves having a first greatest thickness and a second set of leaves having a second greatest thickness, said first greatest thickness is smaller than the second greatest thickness. 7. A multi-leaf collimator comprising a support and a plurality of leaves supported by the support, each leaf being movable to allow a selected portion of radiation energy to be blocked, whereby a shape is defined by a portion of radiation energy which is incident at a target, and the shape is controlled by a positioning of the plurality of leaves,wherein at least some of the plurality of leaves comprise a leaf body which includes a first edge portion and a second edge portion, the first edge portion of the leaf body being provided with an elongate recess slidably engaging the support, and the second edge portion of the leaf body being provided with an elongate step slidably engaging the support. 8. The multi-leaf collimator of claim 7 wherein the leaf body comprises a first section including the first edge portion and a second section including the second edge portion, and the first section is thicker than the second section. 9. The multi-leaf collimator of claim 8 wherein the first section of the leaf body is provided with a drive screw adapted to move the leaf body. 10. The multi-leaf collimator of claim 9 wherein the drive screw is provided inside the first section of the leaf body. 11. The multi-leaf collimator of claim 8 wherein the first section of the leaf body has a cross-section in a trapezoidal shape. 12. The multi-leaf collimator of claim 8 wherein the at least some of plurality leaves are arranged such that a first section of a leaf body is adjacent to a second section of another leaf body. 13. The multi-leaf collimator of claim 8 wherein the plurality of leaves comprise a first set of leaves having a first greatest thickness and a second set of leaves having a second greatest thickness, said first greatest thickness is smaller than the second greatest thickness.
054065941	claims	1. High rate injection system of cryogenic pellets, comprising at least a pneumatic first and second stage propulsion system, in which high pressure gas in said first stage is supplied against a piston compressing the propelling gas in said second stage through a quick control valve so as to cause in said second stage an almost adiabatic compression of the same propelling gas and to reach at an inlet port of a launching barrel of a pellet downstream of said second stage a high pressure peak up to about 2000 bars for a typical time of the order of ten to hundreds of microseconds. 2. The high rate injection system of cryogenic pellets of claim 1, wherein said second stage and said launching barrel are separated by a vacuum sealing cutoff valve having extremely reduced dead volumes and adapted to stand high pressures and temperatures. 3. The high rate injection system for cryogenic pellets of claim 1, characterized in that the propelling gases and the pellet shot by the launching barrel are fed to decompression chambers connected to a vacuum pump system in series upstream of the user's machine and are provided with dynamic impedances and turbulence chambers to delay the flow of the gases and with cutoff means to entrap the gases after the pellet is shot. 4. The high rate injection system for cryogenic pellets of claim 1, wherein the quick control valve (3) between the first (2) and the second (4) stages includes a cylindrical pressure-containing member or shutter (3a) which is pneumatically pushed into the seat, (3b) by the pressure gas supplied upstream into a chamber (50), the backward movement of said shutter being made extremely quick by a shoulder (56) on which the high pressure in the first stage (2) is acting when chamber (50) is evacuated to the atmosphere. 5. The high rate injection system for cryogenic pellets of claim 2, wherein said cutoff valve is a slide valve (6) formed of a blade (65) sliding into a seat formed in a valve body (61) and provided with a hole (66) for an opening and a closure of a channel (72) connecting said second stage (4) and said launching barrel (7), the movement of said slide valve being controlled by a pneumatic actuator. 6. The high rate injection system for cryogenic pellets of claim 3, wherein said impedances of the decompression chambers (11, 12) are formed of straight pipes (82) which extend within said decompression chambers axially with the cutoff valves, have diameters lower than the width of the decompression chambers but larger than the diameter of the pellet, and are provided at their ends with shaped ports (84) and nozzles (86) forming turbulence chambers. 7. The high rate injection system for cryogenic pellets of claim 3, wherein said decompression chambers have reduced overall dimensions and a capacity of the order of 100-200 liters. 8. The high rate injection system for cryogenic pellets of claim 1, including a drawing pipe for a refrigerating fluid (gas) adapted to draw saturated vapors at constant temperature independently of the level of liquid in a Dewar flask and without mechanical movement within said flask. 9. The high rate injection system for cryogenic pellets of claim 8, wherein said drawing pipe (16) is formed of a pair of concentric pipes, an outer pipe being closed at its end immersed into said Dewar flask, and an inner pipe (16d) within said outer pipe and communicating therewith by an innerspace (16c) between said concentric pipes at ends thereof, holes (16e) for the inlet of vapor into said interspace (16c) being formed in said outer pipe at a level which cannot be reached by the liquid in said Dewar flask. 10. The high rate injection system for cryogenic pellets of claim 1, including one or more cryostats in which the cryogenic pellet is formed by the solidification of small gas volumes in a chamber (90) corresponding to the cold point at the lower end of said launching barrel (7) which is supported by a body (94) adapted to move axially and to rotate with respect to a fixed base (95), in which two seats are formed, a dead seat (97) and a seat (96) connected to the pneumatic propulsion system, the pellet being solidified slowly under a thermal gradient suitably controlled by a heater (100) so as to simulate the typical condition of the growth of single crystals when said launching barrel (7) is located on said dead seat (97), the pellet being launched at the end of the solidification after it is carried to said seat (96). 11. The high rate injection system for cryogenic pellets of claim 1, wherein said at least one pneumatic propulsion system is a multi-stage system. 12. The high rate injection system for cryogenic pellets of claim 1, wherein said launching barrel is more than one. 13. The high rate injection system for cryogenic pellets of claim 2, characterized in that the propelling gases and the pellet shot by the launching barrel are fed to decompression chambers connected to a vacuum pump system in series upstream of the user's machine and are provided with dynamic impedances and turbulence chambers to delay the flow of the gases and with cutoff means to entrap the gases after the pellet is shot. 14. The high rate injection system for cryogenic pellets of claim 2, wherein the quick control valve (3) between the first (2) and the second (4) stages includes a cylindrical pressure-containing member or shutter (3a) which is pneumatically pushed into the seat (3b) by the pressure gas supplied upstream into a chamber (50), the backward movement of said shutter being made extremely quick by a shoulder (56) on which the high pressure in the first stage (2) is acting when chamber (50) is evacuated to the atmosphere. 15. The high rate injection system for cryogenic pellets of claim 3, wherein the quick control valve (3) between the first (2) and the second (4) stages includes a cylindrical pressure-containing member or shutter (3a) which is pneumatically pushed into the seat (3b) by the pressure gas supplied upstream into a chamber (50), the backward movement of said shutter being made extremely quick by a shoulder (56) on which the high pressure in the first stage (2) is acting when chamber (50) is evacuated to the atmosphere. 16. The high rate injection system for cryogenic pellets of claim 3, wherein said cutoff valve is a slide valve (6) formed of a blade (65) sliding into a seat formed in a valve body (61) and provided with a hole (66) for an opening and a closure of a channel (72) connecting said second stage (4) and said launching barrel (7), the movement of said slide valve being controlled by a pneumatic actuator. 17. The high rate injection system for cryogenic pellets of claim 4, wherein said cutoff valve is a slide valve (6) formed of a blade (65) sliding into a seat formed in a valve body (61) and provided with a hole (66) for an opening and a closure of a channel (72) connecting said second stage (4) and said launching barrel (7), the movement of said slide valve being controlled by a pneumatic actuator. 18. The high rate injection system for cryogenic pellets of claim 4, wherein said impedances of the decompression chambers (11, 12) are formed of straight pipe (82) which extend within said decompression chambers axially with the cutoff valves, have diameters lower than the width of the decompression chambers but larger than the diameter of the pellet, and are provided at their ends with shaped ports (84) and nozzles (86) forming turbulence chambers. 19. The high rate injection system for cryogenic pellets of claim 5, wherein said impedances of the decompression chambers (11, 12) are formed of straight pipe (82) which extend within said decompression chambers axially with the cutoff valves, have diameters lower than the width of the decompression chambers but larger than the diameter of the pellet, and are provided at their ends with shaped ports (84) and nozzles (86) forming turbulence chambers. 20. The high rate injection system for cryogenic pellets of claim 4, wherein said decompression chambers have reduced overall dimensions and a capacity of the order of 100-200 liters.
	claims	1. A Boron neutron cancer treatment system, comprising:a moderator chamber filled with liquid or granular moderator material except for a central treatment chamber, the moderator chamber having parallel upper and lower surfaces;a plurality of neutron generators, each comprising a pre-moderator block of moderating material having an upper surface, a lower surface, a first and a second end, opposite side surfaces, a first length, a first width less than the first length, and a first thickness, a cylindrical acceleration chamber having a first diameter the first width of the pre-moderator block, sealed at one end to the upper surface of the pre-moderator block adjacent the first end of the pre-moderator block, with a vertical axis perpendicular to the upper surface, the acceleration chamber having a height and a top cover at a second end away from the pre-moderator block, a vacuum pump engaging the acceleration chamber, evacuating the acceleration chamber to a high vacuum, a plasma ion chamber opening into the acceleration chamber through an ion extraction iris through the top cover of the acceleration chamber on the vertical axis of the acceleration chamber, a gas source providing deuterium gas to the plasma ion chamber, a microwave energy source ionizing the gas in the plasma ion chamber, a cylindrical primary isolation well extending a distance into the pre-moderator block from the upper surface, centered on the vertical axis of the acceleration chamber, a secondary isolation well in a shape of a hollow cylinder surrounding the primary isolation well, to a depth somewhat less than the distance of the primary isolation well, within the first diameter of the acceleration chamber, a water-cooled titanium target disk having a target surface orthogonal to the axis of the acceleration chamber, the target disk having a diameter smaller then a diameter of the isolation well, positioned at a lower extremity of the isolation well, the target disk biased to a negative DC voltage, and electrically grounded metal cladding covering all otherwise exposed surfaces of the pre-moderator block; and mechanical adjustable carriers for the neutron generators, each carrier supporting one neutron generator, and enabled to translate the neutron generator toward and away from the central treatment chamber, and to rotate the neutron generators in a plane parallel to a plane of the parallel upper and lower surfaces of the moderator chamber;wherein the modular generators and the mechanical adjustable carriers are fully immersed in the liquid or granular moderator material of the moderator chamber.
052672913	abstract	In a fuel bundle for a boiling water nuclear reactor, modification of the spacers at the peripheral spacer band is made to maintain a more uniform spacing of the peripheral fuel rods from the channel walls to avoid critical power limitations. The conventional fuel bundle construction include a plurality of side-by-side sealed vertically disposed nuclear fuel rods in a square array supported at a lower tie plate, at least some of the fuel rods fastened to an upper tie plate, and held in designed spaced apart relation as a unitary mass by intermittent vertically placed spacers. A square sectioned channel surrounds the upper tie plate, the lower tie plate, and the fuel rods and spacers therebetween. The square sectioned channel functions to confined fluid flow interior of the fuel bundle between the tie plates and through the fuel rods. At the same time, the channel separates a core bypass region exterior of the channel having high moderator density from the flow path interior of the fuel bundle. The spacers are modified at their peripheral band to prevent the spacer confined group of fuel rods closing on the channel wall due to overall migration of the fuel rods as a group held together by the spacers. According to the invention, two adjacent spacer sides are formed with at least two protrusions--typically in the form of bubble like projections, these protrusions occupying the entire interval necessary to maintain the fuel rods adjacent the sides at their full optimal spacing from the interior channel walls. Similarly, the remaining two adjacent spacer sides are formed with protrusions--again in the form of bubble like projections, these protrusions occupying a sufficient interval to prevent inadvertent closing of the fuel rods to the channel sides beyond a worst case limit. This worst case limit is chosen to provide the peripheral fuel rods with adequate clearance to avoid critical power limitation and yet leave sufficient clearance between the peripheral band and the channel so that the channel may be conveniently assembled to the fuel bundle. On these two remaining sides of the peripheral spacer band, leaf springs are added. These leaf springs are preferably vertical in their longitudinal dimension, fastened to the band at one end, bulged outwardly toward the channel in the middle, and bent inwardly and bearing in sliding relation on the band at the opposite end. In operation, the leaf springs are given sufficient force to bias the fuel rod matrix at the spacer away from the channel wall. Such biasing registers the full dimension protrusions to the channel wall at the opposite sides of the spacer and uniformly spaces the peripheral fuel rods with respect to the channel. Bundle critical power is enhanced.
051397323	abstract	The heating rod (3c) is cut from inside the casing (2) of the pressurizer in at least one zone (18, 19) by means of a cutting operation controlled remotely, and at least one portion (20a, 20b, 20c) of the rod (3c) is extracted by way of an inspection port (7) of the casing (2). The invention also relates to robotized cutting devices making it possible to carry out the cutting of heating rods (3) inside the casing (2) of the pressurizer (1).
	claims	1. A therapeutic energy application system comprising:a laser energy source;an x-ray energy source;an energy probe insertable into a tissue at a first position;a stylet removably insertable into the energy probe, wherein the stylet is in the energy probe when the energy probe is inserted into the tissue, and wherein the stylet is configured to be removed from the energy probe after the energy probe is inserted into the tissue at the first position;a laser optical fiber configured to be connectable to the laser energy source, the laser optical fiber removably insertable into the energy probe after the stylet is removed from the energy probe, and configured to emit laser energy to heat and ablate tissue;an x-ray optical fiber configured to be connectable to the x-ray energy source, the x-ray optical fiber removably insertable into the energy probe after the stylet is removed from the energy probe and when the laser optical fiber is not in the energy probe;a sensing probe separate from the energy probe, the sensing probe configured to be independently and separately inserted into the tissue at a second position spaced apart from the first position and configured to detect at least one temperature; andat least one microprocessor configured to co-act with the laser energy source, the x-ray energy source, and the at least one sensing probe to:send a signal to the laser energy source to change the amount of laser energy generated,receive a signal from the at least one sensing probe indicating a detected temperature, andsend a signal the x-ray energy source to change the amount of x-ray energy generated. 2. The therapeutic energy application system of claim 1, including at least one display device configured to co-act with the at least one microprocessor to display a graphical representation of the signal from the sensing probe indicating a detected temperature. 3. The therapeutic energy application system of claim 1, including at least one input device configured to co-act with the at least one microprocessor to enable an operator to cause the at least one microprocessor to send a signal to the laser energy source to change the amount of laser energy emitted. 4. The therapeutic energy application system of claim 1, including at least one storage device configured to co-act with the at least one microprocessor to store the signal from the sensing probe indicating a detected temperature. 5. The therapeutic energy application system of claim 1, including at least one input device configured to co-act with the at least one microprocessor to enable an operator to cause the at least one microprocessor to send a signal to the x-ray energy source to change the amount of x-ray energy emitted. 6. The therapeutic energy application system of claim 1, wherein the microprocessor is further configured to co-act with the laser energy source, the x-ray energy source, and the sensing probe, to send a signal to at least one of the laser energy source and the x-ray energy source to cause at least one of the laser energy source and the x-ray energy source to stop emitting energy. 7. The therapeutic energy application system of claim 1, wherein the at least one energy probe includes a substantially constant diameter along the energy probe, such that the energy probe does not maintain a cavity during an application of therapeutic energy. 8. The therapeutic energy application system of claim 7, which does not include a balloon. 9. The therapeutic energy application system of claim 1, wherein a surgical excision of tissue is performed coincident to the at least one microprocessor co-acting with the laser energy source, the x-ray energy source, and the sensing probe. 10. The therapeutic energy application system of claim 1, wherein the sensing probe is configured to detect at least one dosage amount. 11. The therapeutic energy application system of claim 10, including at least one display device configured to co-act with the at least one microprocessor to display a graphical representation of the signal from the sensing probe indicating a detected temperature and to display a graphical representation of the signal from the sensing probe indicating a detected dosage amount. 12. The therapeutic energy application system of claim 10, including at least one storage device configured to co-act with the at least one microprocessor to store the signal from the sensing probe indicating a detected temperature and to store the signal from the sensing probe indicating a detected dosage amount.
	description	Embodiments of the present invention relate to image display methods and, more particularly, to image display methods focusing on a region of interest (ROI) of an imaged zone within a more extended field of view (FOV) of this imaged zone. In an embodiment of the present invention, the imaged zone can be part of a body of a human being. The imaged zone can be a part of an object exposed to a radiation source. Radiation can be X-ray radiation, but sources using other types of radiation can be used. While imaging part of a body of a human being, the amount of radiation emitted by the source and received by patients whose body is imaged as well as operators manipulating the imaging system, should be reduced. Therefore, to reduce the amount of radiation received by the patient, one efficient way is to limit the exposure of the anatomical part of body to be imaged. Minimizing the amount of ionizing radiation used during x-ray guided interventional procedure is of importance to protect both patients and operators. Several strategies can be used as part of standard radiation protection practice. In particular, collimating the x-ray beam to limit exposure to the anatomical region being treated is very effective as it limits the x-ray beam to the required area. However, this comes at the expense of not being able to see the surrounding anatomical context. In addition, collimating to the right anatomical area requires operator action. This is the reason why collimation is often underutilized, thus leading to larger than necessary exposed area. Currently, it is known to display one image showing at the same time the whole field of view of imaged zone as well as the more limited region of interest in the middle of the field of view. To be able to limit radiation exposure and frequently update information on the region of interest, the refreshing rate of the region of interest of the imaged zone is notably higher than the refreshing rate of the rest of the field of view surrounding the region of interest of the imaged zone. However, even if satisfactory at first sight, this method has several drawbacks. When displaying the region of interest and field of view of an imaged zone in a single image on a single display window, the region of interest being within the center of field of view, choosing the size of the image to be displayed leads to a compromise. Either a limited size of displayed image is chosen or a big size of displayed image is chosen. If a limited size of displayed image is chosen, then the size of the displayed region of interest on the screen may be too small to be easily exploited by the operator. If a big size of displayed image is chosen, then the screen may be too cumbersome. Of course, a compromise can be chosen in between; but for the relatively big size of image, the size of the displayed region of interest on the screen may then appear as too narrow. Besides, in this method, the region of interest is not displayed in optimal conditions; indeed, the size of the displayed region of interest on the screen is too small. An object of the present invention is to alleviate at least the above mentioned drawbacks. More particularly, according to an embodiment of the present invention, an image display shows, on at least two different display windows of reasonable size, both the region of interest and the field of view, the region of interest being refreshed at a higher refreshing rate than the field of view. That way, both images can be optimized independently, the region of interest image so as to be easily exploited by the operator without needing too big a display window, and the field of view including the region of interest so as to locate the region of interest within the rest of field of view of imaged zone in a reasonable size display window, without impairing detailed exploitation of region of interest, since such detailed exploitation is no more performed in this display window. An embodiment of the present invention comprises displaying a first image of an imaged zone in a first display window, displaying a second image of only part of said imaged zone in a second display window distinct from said first display window, a majority of said first image being refreshed at a lower refreshing rate than said second image. In an embodiment, all said first image is refreshed at a lower refreshing rate than said second image. An embodiment of the present invention comprises a first display window adapted to display a first image of an imaged zone, a second display window, distinct from said first display window, adapted to display a second image of part of said imaged zone, a refreshing system adapted to refresh a majority of said first image at a lower refreshing rate than said second image. In an embodiment, all said first image is refreshed at a lower refreshing rate than said second image. More particularly, this image display system comprises a single collimating system which is adapted to collimate an electromagnetic beam which is sent on said imaged zone to capture said first and second images and which is also adapted to switch between said first and second images. An embodiment of the present invention comprises an imaging system comprising a radiation source adapted to radiate on an imaged zone, a radiation detector adapted to receive radiation from said imaged zone so as to detect a first image of said imaged zone and a second image of only part of said imaged zone, and a collimating system adapted to collimate radiation emitted by said radiation source. The imaging system further comprises a control system adapted to control said collimating device so as to refresh a majority of said first image detected by said radiation detector at a lower refreshing rate than said second image detected by said radiation detector, and an image display system including a first display window adapted to display said first image received from said radiation detector and a second display window, distinct from said first display window, adapted to display said second image received from said radiation detector. In an embodiment, all said first image is refreshed at a lower refreshing rate than said second image. Some embodiments comprise one or more of the following features, which may be taken separately or in partial combination or in full combination. In an embodiment of the present invention, the first refreshing rate of the first image is at least twice smaller than the second refreshing rate of the second image or, in an embodiment, is at least five times smaller than the second refreshing rate of the second image or, in an embodiment, is at least ten times smaller than the second refreshing rate of the second image. In an embodiment of the present invention, said first image is displayed on a first display screen and said second image is displayed on a second display screen distinct from said first display screen. That way, both screens can be kept in very reasonable range of size, one bigger screen may cost more than two smaller screens. In an embodiment of the present invention, said second image is a zoom of only part of said first image. That way, while still keeping a reasonable size of display window and of associated screen, more optimal exploitation of information contained is said second image is made possible. In an embodiment of the present invention, said second image is displayed over a larger or equal screen area than said first image. That way, while still keeping a reasonable size of display window and of associated screen, even more optimal exploitation of information contained is said second image is made possible. Other image processing can be applied on one of the images and not on the other. Other image processing can be applied on both images but in a first way on first image which is different from a second way on second image. In an embodiment of the present invention, a box framing said second image is displayed in said first image. That makes easier for the operator the quick location of region of interest within the rest of field of view. In an embodiment of the present invention, said imaged zone is part of a body of a human being. In this field, the level of radiation received by the imaged zone if particularly critical. In an embodiment of the present invention, said imaged zone is imaged by medical X-ray imaging In an embodiment of the present invention, said imaged zone is imaged by medical dynamic X-ray imaging. In an embodiment of the present invention, an electromagnetic beam collimated with a collimating system is sent on said imaged zone to capture said first and second images and switching between said first and second images is performed with same said collimating system. This saves material resources in the global imaging system. This is made possible by choosing a substantially lower refreshing rate for said first image showing field of view, since said field of view does not need such a high refreshing rate as region of interest, since it is to be used by the operator only from time to time and only to perform a rough localization of region of interest within field of view. In an embodiment of the present invention, said collimated electromagnetic beam is pulsed at a pulse rate corresponding to a pulse period, where a duration of opening or of shutting said collimating system is longer than the pulse period or, in an embodiment, is longer than two pulse periods or, in an embodiment, is longer than five pulse periods. The duration of opening and shutting said collimating system should not be too long. In an embodiment of the present invention, the duration of opening or of shutting said collimating system is shorter than twenty pulse periods or, in an embodiment, is shorter than ten pulse periods. In an embodiment of the present invention, one or more pulses are not sent during opening and shutting of said collimating system. This allows avoiding emitting radiation that will produce intermediate images, images intermediate between region of interest and field of view, which indeed are not useful and need not be used by the operator. This helps make sure that all the radiation received by the imaged zone is “useful” radiation, which is radiation used to make images which are useful and which will be exploited by the operator, because those images are really needed and not only because those images have to be exploited since radiation has been emitted. In an embodiment of the present invention, said first image is a single and full capture of said imaged zone, especially when one or more pulses are not sent during opening and shutting of said collimating system. Alternatively, said first image is a combination of several captured images, some of them containing only part of said imaged zone. This combination allows to refresh parts of field of view closer to region of interest to be refreshed more often than parts of field of view farther from region of interest, what can be useful, since the parts of field of view closer to region of interest are more critical than the parts of field of view farther from region of interest. In an embodiment of the present invention, the first image is representing the field of view of an imaged zone and second image is representing a region of interest of the field of view of this imaged zone, the region of interest being smaller than the field of view and the region of interest being a portion only of the field of view, and the first image being refreshed at a first refreshing rate smaller than a second refreshing rate of second image. There are several embodiments for the refreshing rate of the region of interest located within the field of view in the first image. In an embodiment of the present invention, the region of interest in the first image is refreshed at a first refreshing rate, that is, at the same refreshing rate that the rest of the field of view. Manipulation of information in the first image is rather simple and consistent between field of view and region of interest. However, region of interest is not updated as much as it could. In an embodiment of the present invention, the region of interest in the first image is refreshed at a second refreshing rate, that is, at the same refreshing rate as the region of interest in the second image. The region of interest is updated as much as possible, but there may be some inconsistency between the region of interest and field of view, because of too big a difference between first and second refreshing rates. In an embodiment of the present invention, the region of interest in the first image is refreshed at a third refreshing rate, this third refreshing rate being greater than the first refreshing rate but being smaller than the second refreshing rate. Region of interest updating is an intermediate between first and second embodiments, and there is a more consistency between region of interest and field of view than in second embodiment but less than in first embodiment. This intermediate value between first and second refreshing rates may help to make a better compromise in some cases. In an embodiment of the present invention, capturing said first and second images is done by a detector, with no anti-scatter grid between imaged zone and detector. This option is specifically used when the part of a body which is x-rayed, is of reduced thickness. In an embodiment of the present invention, the collimating system is switching between said first image showing field of view and said second image showing region of interest. Said first image is being refreshed at a lower refreshing rate than said second image. To perform this in accordance with an embodiment of the present invention, at some periods, only part of the imaged zone is refreshed, whereas other parts of the imaged zone is not refreshed. In an embodiment of the present invention said other part of the imaged zone receives no or little imaging beam. This is done by one of interposing blades between imaging beam source and other part of image zone, and by interposing attenuating filters between imaging beam source and other part of image zone. In an embodiment of the present invention, a means to automate collimation is proposed. Said means automates collimation to a reduced area and at the same time shows the region of interest in the broader anatomical context of the field of view of an imaged zone. An embodiment of the present invention provides an imaging method comprising displaying a first image of an imaged zone and displaying a second image of only part of said imaged zone, said first image being refreshed at a lower refreshing rate than said second image. The method further comprises sending an electromagnetic beam collimated with a collimating system on said imaged zone to capture said first and second images and performing switching between said first and second images with same said collimating system. This imaging method can display both first and second images either on the same display window or on two display windows distinct from each other. If the already existing collimator in imaging system is reused to perform the switching between first and second image, this imaging method could be implemented in existing imaging system as a software only feature, thus resulting in no product cost increase, provided image processing resources can accommodate image pasting. An embodiment of the invention provides an image display method. The image display method comprises displaying a first image of an imaged zone in a first display window; displaying a second image of only a part of the imaged zone in a second display window distinct from the first display window; and refreshing a majority of the first image at a first refreshing rate that is lower than a second refreshing rate of the second image. An embodiment of the invention provides an image display system. The image display system comprises a first display window configured to display a first image of an imaged zone; a second display window, distinct from the first display window, configured to display a second image of only a part of the imaged zone; and a refreshing system configured to refresh a majority of the first image at a first refreshing rate that is lower than a second refreshing rate of the second image. An embodiment of the invention provides an image system. The image system comprises a radiation source configured to radiate on an imaged zone, a radiation detector configured to receive radiation from the imaged zone so as to detect a first image of the imaged zone and a second image of only a part of the imaged zone, and a collimating system configured to collimate radiation emitted by the radiation source. The image system further comprises a control system configured to control the collimating device so as to refresh a majority of the first image detected by the radiation detector at a first refreshing rate that is lower than a second refreshing rate of the second image detected by the radiation detector, and an image display system. The image display system comprises a first display window configured to display the first image received from the radiation detector, and a second display window, distinct from the first display window, configured to display the second image received from the radiation detector. Further features and advantages of the present invention will appear from the following description of embodiments of the present invention, given as non-limiting examples, with reference to the accompanying drawings listed hereunder. All FIGS. 1 to 6 are shown with a region of interest (ROI) which is a centered square of the field of view (FOV). Nevertheless, other suitable ways of delimiting the region of interest ROI in the field of view FOV, for example a non-centered rectangle, may be used. FIG. 1 shows an example of image including a region of interest ROI within a field of view FOV according to some embodiments of the present invention. An imaged zone I corresponds to a field of view FOV including in its center a region of interest ROI. The field of view FOV covers 100% of the imaged zone I. The rest of the field of view FOV corresponds to the periphery of the imaged zone surrounding the region of interest ROI. Here the region of interest ROI covers about 11% of the whole field of view FOV, whereas the rest of the field of view FOV covers about 89% of the whole field of view FOV which corresponds to the imaged zone I. FIG. 2 shows an example of a closing and opening of a collimating device to make first and second images to be displayed according to some embodiments of the present invention. An Interventional x-ray imaging system will be operated in a new mode, in particular to make use of an off-the-shelf collimator and a new display mode. X-ray radiation is pulsed at pulse rate P. The collimator will close and open cyclically during exposure. The global cyclic period is T which, for example, ranges from 5 s to 10 s. The closing and opening duration is τ which, for example, ranges from 0.5 s to 1 s. During the closing period, the imaged zone goes from I1 corresponding to the complete field of view FOV to I2 corresponding to the region of interest ROI, going through the intermediate images I3 and I4. During opening period, the imaged zone goes from I2 corresponding to the region of interest ROI to I1 corresponding to the complete field of view FOV, going through the intermediate images I4 and I3. Indeed, soon after the operator depresses the x-ray pedal to start imaging the patient, the collimator blades automatically move until reaching a defined region of interest ROI position corresponding to image I2. It is not the object of the present invention to specifically describe how the region of interest ROI is selected, especially its size and position. It can simply be a zone located at the center of the image whose area is, e.g., ¼th to on 1/9th of the full field of view FOV. Another form, different from a centered square, can be used too, for example a non-centered rectangle, or a centered rectangle or a non-centered square. Although it is desirable that the collimation blades move quickly from the full field of view FOV position corresponding to the image I1 to the region of interest ROI corresponding to the image I2 position, it is not necessary that this happens between two x-ray exposures, e.g. sixty-seven (67) milliseconds if the patient is imaged at fifteen (15) images per second. While the collimation blades close, the image processor of the x-ray system keeps memory of successive images, here for example images I3 and I4, and, in a given image, replaces the dark area due to the presence of the collimator blades by the most recent image information available prior to the blades reaching this position. This allows showing the region of interest ROI at a nominal frame rate in its broader anatomical context encompassing the full field of view FOV. As this information can become quickly irrelevant because of natural anatomical motion or because the operator wants to image a different zone, the collimator will open to the full field of view FOV every few seconds automatically, or based on changes of imaging conditions, such as table top or gantry motion, or under a specific operator action, such as a change of the field of view FOV size, a change of the region of interest ROI size or position, etc. During this process, the image is refreshed using the same process as already described. This process is repeated as the operator continues pressing the x-ray pedal. Typically, the collimator may close or open within half a second and the process may be repeated every 5 seconds. The curve (C) shows the Dose Area Product (DAP) plotted versus time. Although this is not the object of the present invention to present specific image processing algorithms, two possible, simple implementations of the processing to eliminate the collimator blades from the image are mentioned. The first one is a form of peak detection that retains the maximum pixel value outside the region of interest ROI. Another possibility is a modified traditional fluoroscopic noise reduction filter which is a recursive low pass filter. Obviously, more sophisticated processing is possible. FIG. 3 shows a curve showing the radiation dose reduction when using different refreshing rates for first and second images to be displayed according to some embodiments of the present invention. The duration of opening or of shutting said collimating system is notably longer than the pulse period. The curve C of FIG. 2 is shown again, whereas the saved dose (SD) of radiation received by the imaged zone is shown too. The exposed area (EA), expressed in percentage, is plotted versus the time, expressed in seconds. Clearly, refreshing the full field of view FOV at a notable lower rate than the region of interest ROI allows for a notably high saved dose. Interestingly enough, this mode can allow operating without an anti-scatter grid. When the exposed area becomes small, typically 12 cm or less, it becomes advantageous to remove the anti-scatter grid for small patient thickness, because scatter rejection will not so easily make up for the signal loss due to grid absorption. Indeed, contrast-to-noise can be made better without grid at equivalent image quality and lower dose, in about a 10-20% range. Therefore, the proposed scheme could at the same time provide lower Dose Area Product (DAP), representative of the level of radiation received by the imaged zone, and lower skin dose in some circumstances, particularly in pediatric imaging. The curve C is showing the level of this Dose Area Product (DAP) which of course is much greater during the closing and opening phase than during the region of interest ROI stable position. Moreover, the proposed mode could be further leveraged to provide means for scatter radiation correction in the image. It is known in the art that scatter can be estimated by measuring a signal at the location of the collimator blades. Then correction can be applied to the region of interest ROI based on this measurement. One simple approach is to subtract the mean measurement from the readings at the region of interest ROI. Other more sophisticated methods exist. FIG. 4 shows an example of a displayed image according to the prior art. On a screen (S0), in the same display window, a first image I10 representing the field of view FOV of an imaged zone is displayed. In the center of the first image I10, a second image I20 representing the region of interest ROI is displayed. In the second image I20, there is an object O1 that can be seen. This object O1 is relatively small, so if it is to be seen more clearly by the operator, the operator will have to zoom on the second image I20 which will cover at least part of the surrounding field of view FOV, which will then be no more visible by the operator. Part of first image I10 surrounding the second image I20 is refreshed at a lower rate than the second image I20. Such factors as low refreshing rate, pasting of images taken at different times, not clearly defined blade edges due to a non-punctual x-ray source as well as off-focal radiation, etc. will result in degradation of image quality, with exception of the region of interest ROI. FIG. 5 shows an example of displayed images according to embodiments of the present invention. On a screen S1, or in a first display window of a given screen, a first image I10 representing the field of view FOV of an imaged zone is displayed. In the center of the first image I10, a second image I22 representing the region of interest ROI is displayed. In the second image I22, there is an object O1 that can be seen. This object O1 is relatively small, but it can be seen more precisely on a second screen S2, or in a second display window different from the first display window but on the same given screen. A second image I21 representing the region of interest ROI is also displayed; the second image may be zoomed in on Here, object O1 can be seen more clearly, especially with fewer artefacts or without any of the artefacts which can be created at the border B between the images I10 and I22. Screen S1 is the reference monitor showing the region of interest ROI in the anatomical context of the field of view FOV. Screen S2 is the live monitor showing in detail and or without artefacts the region of interest ROI alone, independently of the field of view FOV. This is quite an interesting mode because the operator requires maximum image quality for the region of interest ROI and can get by with reduced quality for the anatomical background shown in the field of view FOV. The live image I21 is where the eye will focus and the reduced rate image I10 including image I22 will serve as a reference from time to time. The border B between the image I22 representing the region of interest ROI of first image I10 and the rest of the image I10 may be indicated by graphics on the first image I10, for example through a dotted box framing B. From a practical standpoint, two different monitors may be used, or alternatively, a large monitor screen with two fully distinct display windows, one for the first image I10 including image I22, and the other one for the second image I21. FIG. 6 shows examples of curves showing the evolution of the resulting Dose Area Product (DAP) with respect to the frame rate between the second image and the first image. The duration of opening or shutting said collimating system is notably longer than the pulse period. The resulting DAP, expressed in percentage, is plotted versus the image frame rate IRF, expressed in Hertz. Resulting DAP shows the percentage of DAP remaining versus the nominal DAP without the collimating system closing and opening. The three curves DAP1, DAP2 and DAP3, correspond respectively to three different ratios of surfaces between second image and first image, here 10%, 25% and 40%. The higher the ratio between the ROI and FOV areas is, the higher the resulting DAP is relative to the nominal DAP, while keeping in mind that the resulting DAP remains inferior to the nominal DAP, without collimation opening and closing, and the lowest is also the factor by which the nominal DAP is divided. The exposed area of the patient is limited. Radiation is not reduced at the region of interest ROI, with exception of the proposed removal of the anti-scatter grid, but unnecessary exposure to surrounding anatomy is limited. From a practical standpoint, this will provide significant reduction of the DAP. At first order (not accounting for the discrete nature of the x-ray exposure), DAP reduction as defined by the ratio of DAP in the automated region of interest ROI mode to DAP at the full field of view FOV can be approximated by the following equation: DAP ⁢ ⁢ Reduction ≅ α + 2 ⁢ τ T ⁢ ( 1 3 - α + 2 3 ⁢ α 3 2 ) Where α is the ratio between the region of interest ROI and the full field of view FOV areas, T is the period of the close open collimator blade cycle, and τ is the time required by the collimator to fully close or open. Using α= 1/9, T=5 s, τ=0.5 s: the resulting DAP is approximately 16% of nominal DAP. Therefore, such a mode can easily divide the DAP by a factor of 5, depending on characteristics of the collimator, for instance speed, area of the selected region of interest ROI, refreshing rate, and image frame rate. In particular, in very low frame rate modes, collimator closure can be viewed as occurring instantaneously between x-ray exposures, thus providing optimal dose reduction conditions. This written description uses examples to disclose the present invention, including the best mode, and also to enable any person skilled in the art to practice the present invention, including making and using any computing system or systems and performing any incorporated methods. The patentable scope of the present invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.
	summary
040000389	description	DESCRIPTION OF THE PREFERRED EMBODIMENTS In all the illustrations like parts of the nuclear power station are provided with like reference numerals. The nuclear power stations which are illustrated have a direct helium cycle, and each comprise a reactor 1 and the following machine groups: a turbine set 2 with a compressor and a gas turbine, other apparatus namely a heat exchanger 3 and a preliminary cooling apparatus 4, and also a generator 5 and gas conduits which are designated with arrows showing the direction of flow of the working medium, that is to say helium. To receive and support the machine groups 1 to 5 with the gas conduits, rooms such as the room designated as 8 for example are hollowed out from the natural rock 7 in each of which a machine group such as the reactor 1 is arranged. In order to make the rooms such as for example the room 8 accessible from the atmosphere, tunnels are hollowed out from the rock 7 such as for example the tunnel 9 which connects the room for receiving and supporting the machine groups with the atmosphere. The walls of the rooms, for example the wall of the room 8, are provided with a cast-on concrete layer 10 which takes up the pressures acting on the external wall of the machine group and bears on the wall of the room. This concrete layer 10 is cooled by means of a cooling system not shown here but arranged in the concrete layer. The concrete layer is given its own strength by a prestressed cable system and/or by reinforcements in cases where it supports an intermediate wall between two rooms which are subjected to different pressure, for example in the case of the intermediate wall 11. In the access tunnels, as in illustrated for the tunnel 9, there is provided a chamber 9.sup.1 which is adjacent the particular machine group concerned, in this case the reactor 1, and which is secludable by means of a door 12 relatively to the atmosphere. The nuclear power station shown in FIGS. 1 and 3 is accessible from above. The rooms for receiving and supporting the machine group 1 to 5 and the access tunnels 9 are hollowed out substantially vertically in natural rock 7. The other nuclear power station which is shown in FIG. 2 and FIG. 4 is accessible from the rock face 13. The rooms and the tunnels are hollowed out substantially horizontally in the rock. 6 designates a helium store. The tunnels 9 are so large that the machine group to which each tunnel leads can be transported through the said tunnel. At any rate the tunnels are sufficiently large to allow the largest component part of the machine group to be transported through them. For example the tunnel 9 which leads to the reactor 1 is sufficiently large to allow the largest part of the reactor 1 which, as is known per se, is assembled from component parts in the room 8 hollowed out for it, to be transported through this tunnel. The respective machine group can be transported complete through the tunnel concerned in the case of machine groups 2 to 5. The invention is not limited to the selected constructional example of a nuclear plant station with direct helium cycle. It is also possible to construct other nuclear power station systems with different cycles in accordance with the present invention.
047708425	summary	BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is directed to a common bus multinode sensor system that allows multiple remote units to simultaneously transmit over the common bus using frequency division multiplexing and, more particularly, to a system that provides power to the remote units via the bus and allows low speed digital, low frequency analog signals and high frequency analog signals to be transmitted over the bus to receivers which demodulate the analog signals and decode the digital signals. 2. Description of the Related Art Closed loop communication systems for facilities such factories and nuclear power plants require the capability of transmitting digital, low frequency analog and high frequency analog signals from a plurality of spaced apart points to a central location through an environment full of electromagnetic noise. Such systems typically require that the communication medium such as a twisted wire pair, coaxial cable or optical light guide be spread out through a very large complex requiring a media up to two kilometers in length. Prior art methods of providing such closed loop networks typically provide synchronous data transmission over a transmit channel and a receive channel. These systems poll each remote unit separately and, as a result, operate using a time division multiplexing scheme. The use of time division multiplexing does not allow plural sensors to be sampled simultaneously. The prior art systems also require power supplies at each remote unit producing ground loop problems as well as requiring that extra power wires be provided to the remote units. SUMMARY OF THE INVENTION It is an object of the present invention to provide a communications system that allows slow speed digital as well as low frequency and high frequency analog signals to be simultaneously transmitted for a plurality of sensors. It is another object of the present invention to power remote units over a common bus. It is an object of the present invention to provide a remote unit that can interface plural types of sensors. It is also an object of the present invention to provide separate communication channels for each remote unit. It is an additional object of the present invention to allow plural low speed analog signals to be multiplexed. It is a further object of the present invention to provide a low cost remote unit that takes advantage of medium scale integration. It is still another object of the present invention to allow asynchronous data collection. It is an object of the present invention to allow each remote unit to be flexibly assigned different channel frequencies for communication. It is an additional object of the present invention to allow easy addition of remote units. The above objects can be attained by a multinode system that transmits power down a common bus coaxial cable typically using an alternating current power source. Each remote unit connected to the coaxial cable converts the alternating current power to direct current power for an integrated circuit bus interface. The interface is externally pin programmable to provide a carrier at a frequency for a channel assigned to the remote unit thereby providing each remote unit with an individual identity. When plural low frequency analog signals are to be transmitted over the common bus an on-chip multiplexer multiplexes the signals to an off-chip, external analog-to-digital converter. The analog-to-digital converter loads an on chip parallel-to-serial out shift register that applies each bit of the digitized signal serially to an on chip Manchester encoder. The encoder modifies the input voltage of an on chip voltage controlled oscillator operating at the carrier frequency. The modulated frequency oscillator signal is applied to the coaxial cable. Receivers at the end of the coaxial cable can be tuned to the designated carrier frequencies to demodulate and then decode the encoded signal at any time. If a high frequency analog signal is supplied, it is used to directly modify the voltage applied to the voltage controlled oscillator, that is, the carrier frequency is modulated by the high frequency signal and the receiver operating at the carrier frequency demodulates the signal. The integrated circuit is arranged so that the digital circuitry is generally isolated from and on the opposite side of the chip from the analog circuitry so noise immunity is enhanced. The digital and analog circuitry have separate power supplies. The circuit is arranged in a carrier so that critical lead wire runs are held to a minimum. These together with other objects and advantages which will be subsequently apparent, reside in the details of construction and operation as more fully hereinafter described and claimed, reference being had to the accompanying drawings forming a part hereof, wherein like numerals refer to like parts throughout.
	claims	1. A device manufacturing method, comprising:supplying a liquid between an object and a final optical element of a projection system of a lithographic projection apparatus, wherein the lithographic projection apparatus comprises a movable table and the object comprises at least one selected from the following: a sensor, a substrate, a closing plate or other object in or on the movable table, and wherein a cover plate contacts the object and a top surface of the movable table and bridges a gap between the object and the top surface of the movable table, the cover plate being stretchable and having a hole in its interior; andprojecting a radiation beam, through the liquid, onto a radiation-sensitive surface of a substrate. 2. The method of claim 1, wherein the cover plate has a thickness selected from the range of 5 to 50 microns. 3. The method of claim 1, wherein the cover plate comprises an adhesive to adhere the cover plate to the object, the movable table, or both. 4. The method of claim 1, wherein the cover plate comprises plastic. 5. The method of claim 1, wherein the cover plate comprises metal. 6. The method of claim 1, wherein the object is a substrate having a radiation-sensitive material layer. 7. The method of claim 1, further comprising moving the cover plate with respect to the object and the movable table. 8. A device manufacturing method, comprising:supplying a liquid between an object and a final optical element of a projection system of a lithographic projection apparatus, wherein the lithographic projection apparatus comprises a movable table and the object comprises at least one selected from the following: a sensor, a substrate, a closing plate or other object in or on the movable table, wherein a cover plate contacts and at least partly covers over a top surface of the object and of the movable table and bridges a gap between the object and the top surface of the movable table, the cover plate having at least two portions at least partially separable from and movable with respect to each other; andprojecting a radiation beam, through the liquid, onto a radiation-sensitive surface of a substrate. 9. The method of claim 8, wherein the at least two portions are segments, such that the cover plate is segmented, the segments being moveable with respect to each other to cover the gap. 10. The method of claim 9, wherein the segments are movable over each other. 11. The method of claim 8, wherein the object comprises a sensor. 12. The method of claim 8, comprising moving the cover plate, using an actuator, with respect to the object and the movable table. 13. The method of claim 8, wherein the object is a substrate having a radiation-sensitive material layer. 14. A manufacturing method in a lithographic projection apparatus comprising a final optical element of a projection system and a movable table, the method comprising:moving an object comprising at least one selected from the following: a sensor, a substrate, a closing plate or other object for in or on the movable table of the lithographic projection apparatus, from a position out of contact with the movable table into a recess of the movable table and in contact with the movable table, the object comprising a cover plate that extends laterally from the object, wherein the movement of the object into the recess causes the cover plate to come into contact with a top surface of the movable table and bridge a gap between the object and the top surface of the movable table;supplying a liquid between the object and the final optical element; andprojecting a radiation beam, through the liquid, onto a radiation-sensitive surface of a substrate. 15. The method of claim 14, wherein the cover plate has a thickness selected from the range of 5 to 50 microns. 16. The method of claim 14, wherein the object is a substrate having a radiation-sensitive material layer. 17. The method of claim 14, wherein the object is a sensor. 18. The method of claim 14, wherein the cover plate comprises an adhesive to adhere the cover plate to the object, the movable table, or both. 19. The method of claim 14, wherein the cover plate comprises plastic. 20. The method of claim 14, wherein the cover plate comprises metal.
	claims	1. An apparatus comprising:an internal-external hybrid nuclear reactor comprising:at least one reciprocating internal engine configured to receive internally a nanofuel comprising:a molecular mixture,wherein the molecular mixture comprises: a plurality of components mixed together, wherein at least one of said plurality of components comprises a molecule, the plurality of components of the molecular mixture comprising: i) a fissile fuel, wherein the fissile fuel comprises: a nuclide that undergoes neutron induced fission; ii) a moderator, wherein the moderator comprises: an element capable of: A) thermalizing a neutron population; and B) absorbing a fission fragment kinetic energy; and iii) a passive agent, wherein the passive agent comprises: a nuclide comprising: a resonance neutron absorption cross-section in an epithermal energy range, wherein said resonance neutron absorption cross-section of said passive agent, creates a neutron sink that increases with a nanofuel temperature; and wherein the plurality of components of the molecular mixture provide the nanofuel a nanofuel negative temperature coefficient of reactivity; andat least one external nuclear reactor integrated with said at least one reciprocating internal engine. 2. The apparatus according to claim 1, wherein said at least one reciprocating internal engine comprises at least one or more of:at least one reciprocating piston;at least one cylindrical reciprocating piston;at least one reciprocating engine comprising a plurality of pistons;at least one reciprocating rotary engine;at least one reciprocating rotary engine comprising a plurality of pistons;at least one rotary engine;at least one rotor;at least one reciprocating piston rotary engine;at least one wankel-type rotary engine; orwherein said at least one reciprocating rotary engine comprises the nanofuel placed internally to said at least one reciprocating rotary engine. 3. The apparatus according to claim 1, wherein said external nuclear reactor comprises at least one or more of:at least one plasma core assembly;at least one reflector;at least one Beryllium (Be) reflector;at least one reflector surrounded by at least one solid fuel assembly;at least one solid fuel assembly;at least one solid inverted fuel assembly;at least one core assembly;at least one channel;at least one equivalent annulus;at least one coolant;at least one cladding;at least one gap;at least one fuel;at least one cavity reactor;at least one cavity reactor that is configured to use solid fuel;at least one control drum;at least one Rover Program control drum; orat least one system for nuclear auxiliary power (SNAP) control drum. 4. The apparatus according to claim 1, wherein said internal-external hybrid nuclear reactor comprises at least one or more of:wherein said internal-external hybrid nuclear reactor comprises a compact configuration;wherein said internal-external hybrid nuclear reactor comprises being configured for military applications;wherein said internal-external hybrid nuclear reactor comprises being configured in a small transportable box;further comprising at least one cooling system;further comprising at least one reactivity control;further comprising at least one reactivity control for at least one solid fuel;further comprising at least one control drum;further comprising at least one Rover Program control drum;further comprising at least one system for nuclear auxiliary power (SNAP) control drum;further comprising at least one continuously rotating control drum; orfurther comprising at least one continuously rotating drum producing a burst of energy. 5. The apparatus according to claim 1, wherein said at least one reciprocating internal engine is configured to receive the nanofuel in at least one internal chamber. 6. The apparatus according to claim 5, wherein said at least one reciprocating internal engine is configured to receive the nanofuel in said at least one internal chamber, wherein the nanofuel is produced by a method of obtaining transuranic elements comprising:a) receiving spent nuclear fuel;b) separating transuranic elements from said spent nuclear fuel, wherein said separating comprises:separating said spent nuclear fuel into at least one stream, wherein said at least one stream comprises the transuranic elements comprising at least one or more of:any of all elements with an atomic number Z greater than 92 (Z>92);a fissile fuel;a passive agent;a fertile fuel; ora fission product. 7. The apparatus according to claim 5, wherein said at least one reciprocating internal engine is configured to operate loaded with the nanofuel, a method comprising at least one or more of:a) operating said at least one reciprocating internal engine in a spark ignition mode by injecting neutrons into the nanofuel using a source external to the nanofuel; orb) operating said at least one reciprocating internal engine in a compression ignition mode by creating neutrons in the nanofuel comprising:i) using a radioactive material that emits neutrons. 8. The apparatus configured to operate according to the method of claim 7, wherein said (a) of said operating said at least one reciprocating internal engine in said spark ignition mode by injecting neutrons into the nanofuel using said source external to the nanofuel, comprises at least one or more of:i) using a fusion neutron source; orii) using a radioactive material that emits neutrons. 9. The apparatus according to claim 1, wherein said reciprocating internal engine is configured to use the nanofuel in said reciprocating internal engine comprising:a) compressing the nanofuel in said reciprocating internal engine; andb) igniting the nanofuel using a neutron source, wherein said igniting comprises:triggering a release of nuclear energy from the nanofuel. 10. The apparatus according to claim 1, wherein said at least one reciprocating internal engine is configured to receive and use the nanofuel comprising:a) capturing release of nuclear energy from the nanofuel in said reciprocating internal engine, wherein the nanofuel is also a working fluid in said reciprocating internal engine; andb) using the energy in said working fluid to perform work. 11. The apparatus according to claim 10 wherein the using the energy in said working fluid to perform work comprises at least one or more of:driving an alternator;driving a generator;driving a propeller;generating heat;turning a shaft; orturning at least one wheel. 12. The apparatus according to claim 1, wherein said at least one reciprocating internal engine comprises:at least one engine housing; andat least one reflector. 13. The apparatus according to claim 12, wherein at least one, or more of: said at least one housing, or said at least one reflector, comprises:at least one channel. 14. The apparatus according to claim 13, wherein said at least one channel comprises at least one or more of:a coolant;a reflector; ora moderator. 15. The apparatus according to claim 1, wherein the nanofuel is received into an engine core of said at least one reciprocating internal engine, and said engine core is bounded by a first layer material. 16. The apparatus according to claim 15, wherein said first layer material has a second layer material to resist movement and to create structure. 17. The apparatus according to claim 16, wherein said first layer material comprises Beryllium and wherein said second layer material comprises cement. 18. The apparatus according to claim 1, wherein said internal-external hybrid nuclear reactor comprises at least one of:physically adjacent, or geographically adjacent to any one or more of:a nuclear reactor;a spent nuclear fuel storage facility; ora fuel fabrication facility. 19. The apparatus according to claim 1, wherein fuel of said internal-external hybrid nuclear reactor comprises fuel fabricated from spent nuclear fuel from one or more sources comprising at least one or more of:stored nuclear waste;light-water reactor spent nuclear fuel;nuclear power plant spent nuclear fuel;spent nuclear waste from at least one of: reactor, commercial, industrial, university, military, or governmental source;industrial nuclear waste; ormedical industry nuclear waste. 20. An apparatus comprising:a hybrid energy source comprising:an internal nuclear engine configured to receive internally a nanofuel comprising:a molecular mixture, wherein the molecular mixture comprises:a plurality of components mixed together, wherein at least one of said plurality of components comprises a molecule, the plurality of components of the molecular mixture comprising:i) a fissile fuel, wherein the fissile fuel comprises:a nuclide that undergoes neutron induced fission;ii) a moderator, wherein the moderator comprises:an element capable of:A) thermalizing a neutron population; andB) absorbing a fission fragment kinetic energy; andiii) a passive agent, wherein the passive agent comprises:a nuclide comprising:a resonance neutron absorption cross-section in an epithermal energy range, wherein said resonance neutron absorption cross-section of said passive agent, creates a neutron sink that increases with a nanofuel temperature; andwherein the plurality of components of the molecular mixture provide the nanofuel a nanofuel negative temperature coefficient of reactivity; andan external nuclear reactor integrated with and neutronically coupled with said internal nuclear engine. 21. The apparatus according to claim 1, wherein the at least one reciprocating internal engine provides said internal-external hybrid nuclear reactor with a compact configuration and said at least one internal reciprocating engine is neutronically coupled to said at least one external nuclear reactor. 22. The apparatus according to claim 1, comprising a housing comprising a plurality of layers comprising one or more of:an inner layer adjacent to an engine core of said at least one reciprocating internal engine;a channel;at least one outer layer comprising at least one or more of:a plurality of layers;a layer chosen from a material selected to reduce cost;a layer chosen from a material selected to improve structural integrity;a layer chosen from a material selected to provide manufacturing alternatives;a layer chosen from a material selected to add additional functionality;a sound reduction layer;a noise controlling material;an acoustic panel;a vacuum layer;a Beryllium layer;a graphite layer;an internal channel;a cooling layer;a cost reduction layer;a diagnostic layer;an instrumentation layer;a neutron reflector layer; ora material that reflects neutrons. 23. The apparatus according to claim 9, wherein the method of using the apparatus comprises:a) cooling the nanofuel with a heat exchanger; andb) returning the nanofuel to the at least one reciprocating internal engine.
	description	FIGS. 1 and 2 show the end part of a fuel element 1 for a pressurised water nuclear reactor. The fuel element 1 includes in particular a zirconium alloy tubular sleeve 2 which contains fuel pellets 3 and which is closed at its ends by plugs such as the plug 4 closing the end of the sleeve 2 shown in FIGS. 1 and 2. The plugs 4 are generally made of zirconium alloy and have a part 4a which is inserted virtually without clearance into the end part of the bore of the sleeve 2. As shown in FIG. 1, the plug 4 is inserted into the sleeve 2 in a coaxial arrangement, the axis of the plug and the axis of the sleeve 2 coinciding with the longitudinal axis 5 of the fuel element. The plug 4 has a shoulder perpendicular to the axis 5 between its smaller diameter cylindrical part 4a which is inserted into the sleeve 2 and a part of the plug 4 which remains outside the sleeve. After the plug is inserted in the closure position, a very small annular interstice 6 remains between the shoulder on the plug and the end of the sleeve. After the sleeve is welded, as shown in FIG. 2, the weld 7 fills and closes the interstice 6, joins the sleeve 2 to the plug 4, and seals the joint between the sleeve and the plug. The welding is performed by rotating the sleeve 2 into which the plug 4 is inserted inside a welding station about the axis 5 common to the sleeve and the plug and melting the end of the sleeve 2 and a portion of the plug 4 using a welding device disposed radially relative to the circular joint line between the sleeve and the plug in a joint plane perpendicular to the axis 5 common to the sleeve 2 and the plug 4. The expression xe2x80x9cjoint planexe2x80x9d refers to the area between two planes perpendicular to the axis 5, one plane containing the end of the sleeve 2 and the other plane containing the shoulder on the plug 4. Thus the circular joint line is in fact an annular area extending along the interstice 6 and in which the weld 7 is formed during welding. FIG. 3 illustrates a welding station of a first embodiment of the invention for welding plugs to the end parts of fuel elements by a TIG welding process, i.e. an electrical arc welding process carried out in an inert gas atmosphere using a tungsten electrode. FIG. 3 also illustrates an inspection system for implementing the method according to the invention. The welding station 8 includes a closed and sealed welding chamber 9 which contains an inert gas such as argon and inside which plugs are welded to the end parts of fuel element sleeves. The chamber 9 has on one of its lateral faces a sealed bushing 10 by which an end part of a fuel element 1 analogous to the end part of the fuel element shown in FIG. 1 passes through the wall of the chamber. A vertical TIG welding torch 11 is mounted on the top face of the chamber 9 and includes a vertical tungsten welding electrode 12 which passes through the torch 11 and therefore enters the chamber, the end part of the electrode having an axis constituting the welding axis which is disposed in the joint plane between the plug and the sleeve of the fuel element 1 and in a direction perpendicular to the axis of the fuel element, i.e. a radial direction relative to the circular joint line between the plug and the sleeve of the fuel element 1. To execute the welding, the electrode is fed with an electrical current with a potential difference between the electrode and the sleeve and the plug of the fuel element such that an electrical arc is struck between the joint area between the plug and the sleeve and the tip of the electrode, which is inside the sealed enclosure and at a small distance from the joint area. A first lateral face of the welding chamber 9 perpendicular to the face carrying the sealed bushing 10 for the fuel element 1 includes a transparent porthole 13 through which light is directed towards the joint area of the fuel element by an illumination device 14. This first lateral face of the chamber 9 is referred to as the front face and the illumination device 14 is referred to as the front illumination device. A second or rear face of the chamber 9 carries a porthole and a rear (backlight) illumination device 15 for illuminating the joint area of the fuel element 1. A digital camera 16 including an optical system 16a and a digitizer module is connected to a microcomputer 17 via an image acquisition card. The microcomputer 17 also includes a digital input/output card enabling the microcomputer to communicate with an automatic control system of the TIG welding equipment. In particular, after checking the position of the joint plane relative to the welding axis, the microcomputer communicates to the welding control system an instruction authorising or prohibiting welding, depending on the result of the check on the position of the joint plane. Similarly, a verdict is transmitted to the control system after inspecting the weld. Images of the joint area of the fuel element 1 reach the optical part 16a of the digital camera 16 via the front porthole 13 and are digitized before they are transmitted to the microcomputer 17 via the image acquisition card. The microcomputer 17 has a screen 18 on which the joint area of the fuel element and inspection results can be displayed. As indicated above, a first step of the process of inspecting the weld in accordance with the invention is to check the position of the joint plane between the plug and the sleeve of the fuel element before welding. In the case of TIG welding, the position of the joint plane is determined relative to the axis of the tungsten electrode, the width of the joint plane in the axial direction of the fuel element, and the distance between the tip of the electrode and the joint area of the fuel element, and a diagnosis relating to the position of the joint area relative to the electrode is produced. The joint plane is inspected while sweeping the joint area of the fuel element inside the welding chamber with an inert gas and rotating the fuel element about its axis inside the welding chamber by a rotation system of the welding station. In this way it is possible to locate and determine the position of the joint plane in a plurality of areas distributed around the periphery of the joint area of the fuel element. For example, eight successive operations can be carried out to locate and determine the position of the joint plane in eight areas around the periphery of the fuel element, to determine the conformance of the position of the joint plane relative to the electrode. In this case, in order to issue a verdict concerning the conformance of positioning, it is possible to choose a number of conform searches, i.e. searches which reveal no defects in respect of the position or the width of the joint plane over the total number of joint plane location and determination operations effected. In the case of eight operations to locate and determine the position of the joint plane, for example, the number of conform searches chosen is five. This procedure also verifies that the fuel element has rotated correctly between the successive operations to locate and determine the position of the joint plane. The rotation of the fuel element is deemed to be non-conform if all the positions of the fuel element determined by the successive joint plane location and determination operations are identical. Because the joint plane is in practice an area delimited between two planes perpendicular to the axis of the fuel element, the position of the joint plane is determined by the distance in the axial direction between at least one of the two planes and the axis of the electrode, the latter constituting the welding axis. For example, in the case of the location process described below, the distance between the left-hand edge of the joint plane in the image and the axis of the tungsten electrode in the axial direction is determined. The width of the joint plane corresponds to the axial distance between the end of the sleeve and the shoulder on the plug, i.e. the width of the interstice 6, which may vary along the circular joint line. The first step is to carry out measurements relating to the electrode 12 on the digitized images, as shown in FIGS. 5 and 6. The electrode is first located along an electrode search line 19 which is perpendicular to the joint plane, i.e. which is horizontal in the image displayed on the screen, as may be seen in FIGS. 5 and 6. A search is conducted along the search line 19 to find grey level transitions corresponding to the edges of the electrode 12. If the search does not find the electrode, a fault signal is issued. The electrode search line 19 is automatically centred on a reference line 20. The search line and the reference line 20 are positioned visually if the TIG welding station has been set up correctly. Following location of the electrode, the welding axis can be determined, and in the case of TIG welding corresponds to the axis of the electrode as found previously. A search for the joint plane 22, which corresponds to the interstice 6 between the fuel element and the plug, is then carried out (see FIGS. 5 and 6). To this end, the fuel element and the plug 4 are illuminated in a maximum illumination area 21 inside the welding chamber that can be seen in FIGS. 5 and 6. The joint plane is located along search lines such as the line 19xe2x80x2 in the illuminated area 21 shown in FIGS. 5 and 6. The reference line 20, which is vertical in the image, is positioned at the left-hand edge of a theoretical joint plane, and the search lines are centred on the reference line; the position of the real joint plane is determined by the horizontal distance between the left-hand edge of the joint and the axis of the electrode previously determined. The width of the joint plane is determined by the horizontal distance between the left-hand edge and the right-hand edge of the joint. The right-hand edge and the left-hand edge of the joint plane are looked for on search lines 19xe2x80x2 centred on the reference line 20, using a processing method described below with reference to FIG. 9. The distance between the tip of the electrode 12 and the fuel element is also measured, along the axis of the electrode previously found, i.e. in a vertical direction in the image, by measuring the distance between grey level transitions detected on that axis. The exit of the electrode at the tip is reflected in a black-white transition in the image and its entry into the fuel element by a white-black transition. The entry/exit distance in pixels is measured along a vertical column. FIG. 9 illustrates the search for the joint plane and is a diagram giving the grey levels of pixels along a mean search line which is established during previous processing of the image. A parameter N entered into the processing system corresponds to the number of rows above and the number of rows below the position of the search line, such as the line 19xe2x80x2, and provides a mean of the grey levels over the corresponding 2xc3x97N rows. The parameter N is referred to as the mean number of rows. The curve 23 in FIG. 9 represents the grey levels along the mean line, with the points on the line plotted on the abscissa axis. There are 245 points for the whole of the line, for example. The minimum and maximum values on the curve 23 representing the grey levels along the mean line are determined. A threshold value is calculated and is equal to half the sum of the maximum value and the minimum value determined previously. A straight line segment 24 is drawn parallel to the abscissa axis and corresponds to this threshold value. A search for the left-hand edge of the joint plane is then conducted based on the grey levels of the digitized image pixels, starting from the left-hand end of the mean search line. The left-hand edge is deemed to have been found as soon as three consecutive points are detected below the threshold shown by the straight line segment 24. The left-hand edge 25 of the joint plane is determined in this way. The position of the left-hand edge relative to the edge of the image is determined and the distance between the left-hand edge and the axis of the electrode found previously is calculated. The position of the right-hand edge of the joint plane is then determined by considering the grey levels of the successive pixels from the right-hand end of the mean search line and comparing those grey levels to the threshold value represented by the straight line segment 24. The right-hand edge 26 of the joint plane is deemed to have been reached as soon as three points are detected under the threshold. The width of the joint between the left-hand edge 25 and the right-hand edge 26 can then be determined. The values representative of the position of the joint, i.e. the distance between the left-hand edge of the joint and the axis of the electrode, and the width of the joint, are then compared to thresholds defined by the following parameters: left-hand electrode position tolerance, right-hand electrode position tolerance and maximum width of joint plane. The results of the comparison are shown on the screen of the microcomputer 17. If at least one threshold value is exceeded, a diagnosis is issued and an instruction is transmitted to the control system so that welding is not performed. FIG. 5 illustrates the image appearing on the screen in the case of a satisfactory search for the joint plane 22, which is located exactly along the reference line 20 coincident with the axis of the electrode. FIG. 6 illustrates the image appearing on the screen in the case of a non-conform joint plane, the joint plane 22 being offset to the left relative to the position of the reference line 20. Similarly, unfavourable diagnoses can be issued if the distance between the tip of the electrode and the fuel element is outside the specified range or if the width of the joint plane is above a threshold value. The search for the joint plane and the determination of its position and width can be effected in a plurality of areas at the periphery of the fuel element, which is rotated about its axis. Continuous inspection of the joint plane is also possible by rotating the fuel element and taking successive images, each of which is processed before the next image is taken. After carrying out the TIG welding, during the weld cooling phase, the weld is inspected in order to issue a final verdict on the quality of the weld, which is transmitted to the welding station control system. The weld is inspected by a process identical to the joint plane search process, as described above. The presence of a defect is logged if the joint plane is detected. If two consecutive defects are detected in the weld, inspection is stopped and the weld is declared defective in one area of the fuel element. Inspection continues as long as two consecutive defects are not detected. At the end of inspection the final verdict is sent to the welding station control system. The weld is inspected in accordance with the following sequence: continuous acquisition of images of the weld, the next image being acquired during the processing of the previous image, location of the weld in each image; if N consecutive weld integrity defects are detected (generally two consecutive defects), inspection is stopped and the weld is declared defective; N is the reject threshold parameter, display of results. FIG. 7 illustrates a conform weld in a strongly illuminated area 21 of the fuel element 1, the weld being totally invisible in the image. No part of the joint plane appears in the image. FIG. 8 illustrates a defective weld in a strongly illuminated area 21 of the fuel element 1. The joint plane 22 has been detected in this area. FIG. 4 illustrates a station for welding plugs to fuel elements using a laser beam and a system for inspecting the weld using a method according to the invention. The welding station 28 includes a welding chamber 29 into which the end of the fuel element 1 including the plug is inserted through a sealed bushing device 30 passing through one lateral face of the chamber 29. An adjustable abutment device 31 fixed to the lateral face opposite the face including the bushing device 30 for the fuel element 1 adjusts the position of the joint area of the plug and the sleeve of the fuel element 1 relative to the laser beam welding device. The welding station 8 includes in particular an optical system 32 which includes a mirror for deflecting and focussing the laser beam. The optical system 32 is connected to the laser generator by an optical fibre 27 connected to a collimator 33. The optics 34 of a digital camera 35 and an illumination system 36 are fixed to the top face of an enclosure of the optical system 32. The digital camera 35 is connected to a microcomputer 37 including a display screen 38. As in the case of TIG welding, inspection of the joint plane before welding is followed by inspection of the weld if the joint plane is deemed to be conform. The position of the joint plane is located and determined by a method similar to the method used in the case of TIG welding. The method is therefore not described again. However, the reference line relative to which the position of the edges of the joint plane is determined is defined and determined differently in the case of laser beam welding than in the case of TIG welding. In the case of TIG welding, the reference line serves only to support the search lines 19 and 19xe2x80x2. The position of the joint plane is determined relative to the axis of the electrode, which is detected by image processing. In the case of laser welding, a fixed reference is used in the form of a vertical line on the screen which constitutes a marker relative to which the position of the edges of the joint plane is determined. After setting up the laser welding station, the laser is fired onto the surface of the fuel element and the reference line is chosen as the vertical line of the image passing through the trace of the laser beam. The reference line therefore corresponds to the welding axis. The position of the joint plane relative to the reference line and the width of the joint plane are determined and rotation of the fuel element is verified. FIG. 10 illustrates, in a strongly illuminated area 41 of the fuel element 1, the reference line 40, a joint plane search line 39 and the joint plane 40 and 42. The left-hand edge of the joint plane is coincident with the reference line 40 and the conforming width of the joint plane. FIG. 11 illustrates a non-conform joint plane 42 offset to the right relative to the reference line 40. If the joint plane is conform, a favourable diagnosis is issued and a signal authorising welding is sent to the control system. The welding is effected by a pulsed laser beam while the fuel element is rotating. In FIG. 12, the weld 45 made by the pulsed laser beam and centred on the reference line 40 includes successive waves 44 of substantially circular shape each corresponding to one firing of the laser. The distance between the waves 44 in the vertical direction of the image, representing the circumferential direction of rotational movement of the fuel element, corresponds to the movement between two successive pulses of the laser beam. Digitized images are acquired continuously, the next image being acquired during the processing of the previous image. The left-hand and right-hand edges of the weld are located and their positions relative to the reference line 40 are determined. The width of the weld is also determined, from the positions of the edges of the weld. Because there is a correlation between the width of a laser beam weld and the depth of penetration of the weld, it is possible to determine from the width of the weld how deep the weld has penetrated into the sleeve and the plug of the fuel element. FIG. 13 is a diagram showing the grey levels, on a scale from black to white, of the pixels of an image of the weld in a first column of the image (i.e. along a vertical line of the image, corresponding to a peripheral circular line on the fuel element in a plane perpendicular to the axis of the fuel element) inside the weld and in a second column of the image outside the weld. The curve 46 corresponds to a column of the image outside the weld and the curve 47 to a column of the image inside the weld. The successive waves of the weld are reflected in peaks and troughs indicated by the respective arrows 48 and 49. The arrow 50 shows the distance the fuel element moves in a time period corresponding to the period of the laser beam pulses. Diagrams similar to the FIG. 13 diagram are produced for each column of the image of the weld and each diagram obtained, similar to the FIG. 13 diagram, is searched for pairs of transitions between a trough and a peak which have a period consistent with the period of the welding pulses. The number of transitions consistent with the period of the welding pulses is logged for each column of the weld and for the areas adjoining the lateral edges of the weld. FIG. 14 shows the number of transitions as a function of the columns of the image. FIG. 14 shows the reference line 40 and the peaks corresponding to the number of transitions consistent with the period of the welding pulses for each column of the image. The maximum number of transitions in the portion of the diagram to the left of the reference line 40 is determined, and is referred to as the left-hand maximum. Similarly, the maximum number of transitions in the portion of the diagram to the right of the reference line is determined, and is referred to as the right-hand maximum. The central mean of the transitions between the left-hand maximum and the right-hand maximum is also determined and is shown by the straight line segment 51 parallel to the abscissa axis. A weld is deemed to have been executed on the fuel element if the left-hand maximum and the right-hand maximum are above a particular limit, for example 4, and the central mean is above a particular limit, for example 3. A central mean above a particular limit indicates the presence of a weld in the central area. If the conditions relating to the left-hand maximum and the right-hand maximum and/or the central mean are not complied with, a search for the joint plane is conducted. If the joint plane is not found, inspection continues. If the joint plane is found, a weld integrity defect diagnosis is issued. The FIG. 15 diagram is produced by filtering the FIG. 14 diagram, and shows only transitions relating to the edges of the weld, excluding the central part. A search for the left-hand edge of the weld 45 and a search for the right-hand edge are conducted successively. To this end, a right-hand threshold and a left-hand threshold are calculated to provide a weld edge search criterion. The right-hand threshold is defined by the following equation, in which x is a parameter referred to as the right-hand weld search threshold: RH threshold=RH min+x% of (RH maxxe2x88x92RH min). Similarly, the left-hand threshold is defined by the following equation, in which y is a parameter referred to as the left-hand weld search threshold: LH threshold=LH min+y% of (LH maxxe2x88x92LH min). The values of x and y are determined according to the fuel element illumination conditions. If one of the above parameters is not satisfactory for precise determination of the edges, it is adjusted by entering a new value of the parameter into the processing software. The search for the left-hand edge and the right-hand edge is conducted from threshold values represented by straight line segments 52 and 53 in FIG. 15, for example by searching for a particular number of pixels below the threshold in a first direction from a maximum followed by a pixel above the threshold in the second direction. For example, five points are searched for under the threshold in one direction and then one point above the threshold in the second direction. This produces the position of the left-hand edge and the right-hand edge along the columns of the image, represented in FIG. 15 in the form of vertical segments 55 and 56, and the position and the width of the weld 45 are determined in this way from the number of columns between the left-hand and right-hand edges and between those edges and the edge of the window for determining their positions; these values are compared to threshold values constituting the following parameters of the processing system: left-hand marker, position tolerance and right-hand marker position tolerance. The width is also compared to a threshold value constituting a lack of weld minimum width parameter. If three consecutive widths less than the minimum width are encountered when the successive images of the welds are processed, the absence of a weld is deduced and inspection is stopped. The weld is declared defective. If three consecutive widths less than the minimum width are not encountered, inspection continues and at the end of inspection the positions and widths of the weld are averaged and then compared to the position limits (right-hand position tolerance, left-hand position tolerance) and width limits (minimum weld width) in order to issue a final verdict that is sent to the control system. The results are displayed on the screen of the microcomputer. The rotation of the fuel element is also verified at the end of inspection by examining the measured width of the weld throughout the length. If too few widths depart from the mean value, a diagnosis relating to non-rotation of the fuel element is issued. FIGS. 16 and 17 illustrate the image displayed on the screen at the end of inspection. In FIG. 16 (which is substantially the same as FIG. 12), a conforming weld. In FIG. 17, the weld is non-existent and deemed to be non-conforming. The invention therefore enables the joint plane to be inspected at the welding station itself, prior to welding, and the weld to be inspected with particular reference to the quality and continuity of the weld. The system can operate in masked time relative to the welding operation. In the case of laser beam welding, the penetration of the weld is checked by the correlation between the width of the weld and its penetration. This parameter is meaningless in the case of TIG welding. The method according to the invention is used at the welding station, during the welding operation, which avoids all handling operations to transfer the fuel elements between the welding station and an inspection station. The verdict relating to the conformance of the weld is available as soon as the welding operation is finished. The information concerning the operation as a whole (welding, positioning and inspection) can be saved on a hard disk for use afterwards in the form of a database. Finally, the illumination system used by the imaging means is a standard illumination system available off the shelf. The invention is not strictly limited to the embodiments described. Thus the method of inspecting the joint plane may be applied to any method of welding plugs to nuclear fuel elements. The digitized images of the weld may be processed by methods other than those described in the case of laser beam welding. Finally, the method according to the invention applies to any nuclear fuel element including sealed closure plugs inserted into end portions of the sleeve of the fuel element.
041860497	claims	1. A heat exchanger integrated into the main vessel of a molten combustible salt reactor comprising a reactor vessel containing the active core, a main vessel surrounding said reactor vessel, pumps and primary exchanges, an outer vessel spaced from said main vessel, a coolant between said main and said outer vessel maintaining said main vessel wall at a temperature below the melting temperature of a nuclearly inactive coating of solid salt on and protecting an inner surface of said main vessel, a plurality of autonomous heat transfer modules for removing heat from the core, each of said modules comprising a primary exchanger and a pump, each of said modules being suspended in the space between said main vessel and said reactor vessel, the improvement comprising a first bearing surface at the base of each of said modules, a horizontally extending plate secured around the lower end of said reactor vessel extending toward and spaced from said main vessel and ending in said coating of solid salt, an opening in said plate for each of said modules and a second bearing surface around each of said openings supporting the adjacent one of said first bearing surfaces. 2. A heat exchanger according to claim 1, wherein each of said opening sealingly cooperates with a lower part of said core by a delivery pipe for salt from the pump to the base of the reactor core. 3. A heat exchanger according to claim 1, wherein each of said openings communicates directly with a space in a lower part of said main vessel and beneath said reactor vessel, direct passages in said space for the return of the cold salt to the reactor core, the sealing of said space on the main vessel side being provided by said solid salt coating. 4. A heat exchanger according to claim 3, wherein a free end of said plate is tapered and underlies an annular boss on said main vessel within said solid salt coating. 5. A heat exchanger according to claim 4, wherein said free end of said plate supports on an upper face a graphite sealing element engaging a lower surface of said boss. 6. A heat exchanger according to claim 4 wherein said free end of said plate has on assembly and when cold an external diameter less than the internal diameter of said boss.
053435079	description	DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 schematically shows a shutdown coolign system for operation lapse of power, according to a first embodiment of the invention. Coolant tank 10, being filled with a supply of coolant such as water 15, is coupled in fluid communication with a high pressure pump 30. A plurality of fluid conduits 20 provide a means for fluid communication between the coolant tank 10 and high pressure pump 30. The high pressure pumo 30 is coupled via conduits 20 and junction 60 with the reactor coolant pump (RCP) seals 50. The preferred coolant is water although other fluids can be used. Gases such as air, carbon dioxide, helium and dry steam have been used successfully as coolants in nuclear reactors. Liquids such as water, single-phase pressurized water, two phase boiling water or fog, heavy water, terphenyl, hydrogenated terphenyl, molten bismuth and molten salts such as fluorides have also been successfully used as coolants. Under normal operating conditions junction 60 is arranged, either manually or automatically, such that water circulated by the normal charging pumps 40 is directed through conduits in heat transfer contact with the RCP seals 50. The water directed to the RCP seals is recirculated back to the normal charging pumps 40 and is thereby re-used. If a power failure occurs (i.e., the power generated locally by the turbine/generator, offsite power from the normal electric power grid, and emergency power generated by emergency diesel generators are all lost) the normal charging pump 40 will not be powered and consequently will not function. Therefore under power fail conditions junction 60 is arranged, preferably automatically but also possibly including manual actions, to direct wate from the high pressure pump 30 to the RCP seals 50. Water is suppied from the coolant tank 10, pumped by the high pressure pump 30, through conduits 20, through junction 60, to the RCP seals 50, thereby cooling the RCP seals 50. Valve 21 prevents misdirection of the flow. A low pressure pump 110 is coupled to the existing residual heat removal system (RHRS) 100 and a heat exchanger 120 via conduits 20. Heat exchanger 120 is a water-to-water heat exchanger, and has a primary fluid circuit with an inlet and outlet and a secondary fluid circuit with an inlet and outlet. The heat exchanger is operable to transfer heat from the water flowing through the primary circuit to the water flowing though the secondary circuit. The low pressure pump is coupled to the primary inlet 130 of the heat exchanger 120. The existing reactor coolant system (RCS) 170 is coupled to the primary outlet 140. Water from the RHRS 100, being pumped by the low pressure pump 110, flows into the primary inlet 130, through the primary circuit, out of the primary outlet 140, and into the RCS 170. Water flowing through the RCS is recirculated back to the RHRS 100and is thereby re-used. Valves 23 and 25 provide isolation from the RHRS 100 during normal operation, and open to allow flow via the low pressure pump 110. A cooling water pump 210 is coupled to the existing cooling water system (CWS) 200 and the secondary circuit of heat exchanger 120 via conduits 20. Water from the CWS 200, being pumped by the cooling water pump 210, flows into the secondary inlet 150, through the secondary circuit, out of the secondary outlet 160 and back to the CWS 200. The heat from water in the primary circuit is transferred to the water in the secondary circuit, thereby cooling the water in the primary circuit. Valves 26 and 27 provide isolation from the CWS 200 during normal operation, and open to allow flow via the cooling water pump 210. An independent power source 190, as shown in FIG. 1, is coupled to the high pressure pump 30, low pressure pump 110, and cooling water pump 210, thereby providing power during a power failure. Power from the independent power source 190 may also be routed to other systems where needed, for example power may be needed to automatically re-arrange junction 60 such that water can be directed from the coolant storage tank via the high pressure pump to the RCP seals. Similarly other junctions where the invention is coupled into the existing systems may need to be rearranged to route water to the proper conduits and therefore may also require power from the independent power source. These junctions preferably are arranged with controllable valve (e.g., valves 23, 25, 26, 27) operated by a suitable control system that triggers reconfiguration of the respective flowpaths upon detection of the loss of regular ad emergency power. FIG. 2 shows a second embodiment of the invention having an alternate configuration for residual heat removal, the same reference numbers being used to identify elements that correspond to those of the first embodiment. Cooling water is supplied to the RCP seals in the same fashion as the first embodiment. The high pressure pump 30 circulates water from coolant tank 10 to RCP seals 50 via conduits 20. Valve 21 prevents misdirection of flow. A low presusre pump 110 is coupled to the existing residual eat removal system (RHRS) 100 and a heat exchanger 122 via conduits 20. In this embodiment, the heat exchanger 122 is an air-to-water type, and has a primary fluid circuit with an inlet and outlet and a secondary circuit that is air cooled. The heat exchanger is operable to transfer heat from water flowing through the primary circuit to the air flowing though the secondary circuit. The low pressure pump 110 is coupled to the primary inlet 132 of the heat exchanger 122. Teh existing reactor coolant system (RCS) 170 is coupled to the primary outlet 142 of the heat exchanger 122. Water from the RHRS 100, being pumped by the low pressure pump 110, flows into the primary inlet 132, through the primary circuit, out of the primary outlet 142, and into the RCS 170. Water flowing through the RCS is recirculated back to the RHRS 100 and is thereby re-used. Valves 23 and 25 provide isolation from the RHRS 100 during normal operation, and open to allow flow via the low pressure pump 110. Blower 180 is operable to provide a stream of forced air, flowing over the air cooled secondary circuit 152 of the heat exchanger. The heat from water in the primary circuit is transferred to the air flowing over the air cooled secondary circuit, thereby cooling the water in the primary circuit. An independent power source 190, as shown in FIG. 2 is coupled to the high pressure pump 30, low pressure pump 110, blower 180, and valves (e.g., 23 and 25) as needed, thereby providing power during a power fail condition. FIG. 3 shows a third embodiment of the invention, having an alternate configuration for residual heat removal, the same reference numbers again being used. Cooling water is supplied to the RCP seals in the same fasion as the first and second embodiment. The high pressure pump 30 circuits water form coolant tank 10 to RCP seals 50 via conduits 20. Valve 21 prevents flow misdirection. Low pressure pump 110 is coupled to the existing residual heat removal system (RHRS) as shown in the first and second embodiment. The heat exchanger 120 can be a water-to-water type, and has a primary fluid circuit with an inlet and outlet and a secondary fluid circuit with an inlet and outlet. The heat exchanger is operable to transfer heat from water flowing through the primary circuit to water flowing though the secondary circuit. The low pressue pump is coupled to the primary inlet 130 of the heat exchanger 120. The existing reactor coolant system (RCS) 170 is coupled to the primary outlet 140 of the heat exchanger 120. Water from the RHRS 100, being pumped by the low pressure pump 110, flows into the primary inlet 130, through the primary circuit, out of the porimary outlet 140, and into the RCS 170. Water flowing through the RCS is recirculated back to the RHRS 100 and is re-used. Valves 23 and 25 provide isolation from the RHRS 100 during normal operation, and open to allow flow via the low pressure pump 110. Colling water from the coolant tank 10 is circulated though the heat exchanger secondary circuit by the high pressure pump 30 via conduits 20. Water from the coolant tank 10, being pumped by the high pressure pump 30, flows into the secondary inlet 150, through the secondary circuit, out of the secondary outlet 160 and back to the CWS 200. Valve 28 and 29 isolate this high pressure cooling from the normal system. The heat from water in the primary circuit is transferred to the water in the secondary circuit, thereby cooling the water in the primary circuit. An independent power source 190, as shown in FIG. 1 is coupled to the high pressure pump 30, low pressure pump 110 and valves (e.g., 23, 25, 28, 29) as needed, thereby providing power during a power fail condition. FIG. 4 shows a flow chart illustrating automatic activation of the high pressure pump of a preferred cooling system according to the invention, upon sensing a loss of power during particular coolant temperature and pressure conditions. The high pressure pump is automatically activated depending on temperature or pressure conditions in the reactor coolant system (RCS). If the RCS temperature rises above a pre-determined level, such as 320.degree. C., or the RCS pressure drops below a predetermined level, such as 130 bar, the high pressure pump is activated automatically. Additionally if all other sources of power are lost, the independent power source and the high pressure pump are activated. Upon starting the high pressure pump, it is also necessary to open the proper valves such that cooling water circulated by the high pressure pump is directed to the RCP Seals. Under normal conditions the normal charging pumps circulate cooling water to the RCP seals, and the high pressure pump is inactive. However if the RCS temperature or pressure deviates from the normal operating conditions, and the high pressure pump is automatically activated, controllable valves at the respective junctions are automatically opened, in known manner. Teh valves route the flow of cooling water to the RCP seals as shown. Appropriate redundant valves or conduits and check valves can be provided, to ensure operation in an emergency situation while having no effect on normal reactor operation. If there is a power fail condition, the independent powre source is actuated. The independent power source may provide either AC or DC power of both. The high pressure pump and the automatic valves are powered by the independent power source. The high pressure pump are automatically activated and the various valves automatically opened, to properly route the flow of cooling water to the RCP seals under power fail conditions. FIG. 5 shows a flow chart illustrating actuation of the low pressure pump. The low pressure pump is automatically activated upon detection of either a power fail condition or valves fom the RHRS being opened. Under normal conditins, various pumps and heat transfer means of the RHRS transfer residual heat away from the reactor core. If a power fail condition occurs, the independent power source and the low pressure pump are activated, the low pressure pump being powered from the independent power source. In the first embodiment of the invention as shown in FIG. 1, the low pressure and cooling water pumps are activated, both pumps being powered from the independent power source. The respective valves are automatically opened such that water is circulated though the primary circuit of the heat exchanger by the low pressure pump and water is circulated though the secondary circuit of the heat exchanger by the cooling water pump. In the second embodiment of the invention as shown in FIG. 2, the low pressure pump and blower are activated, the blower and pump being powered from the independent power source. The respective valves are automatically opened such that water is circulated though the primary circuit of the heat exchanger by the low pressure pump, the secondary circuit of the heat exchanger being cooled by air flow generated by the blower. In the third embodiment of the invention as shown in FIG. 3, the low pressure pump and respective valves are automatically actuated such that water is circulated though the primary circuit of the heat exchanger by the low pressure pump and water is circulated though the secondary circuit of the heat exchanger by the high pressure pump. It may be desirable in certain situations to activate the low pressure pumps in non-power-fail conditions. In that case, the system can be operable to detect when the RHRS primary valves are opened and automatically to start the low pressure cooling pumps. The invention having been disclosed in connection with the foregoing variations and examples, additional variations will now be apparent to persons skilled in art. The invention is not intented to be limited to the variations specifically mentioned, and accordingly reference should be made to the appended claims rather than the foregoing discussion of preferred examples, to assess the scope of the invention in which exclusive rights are claimed.
	claims	1. An electron microscope equipped with a magnetic microprobe, the microscope creating an image of a specimen made of a magnetic material based on an electron beam transmitted through the specimen, said microscope comprising:a nonmagnetic holder for holding said specimen made of the magnetic material;said magnetic microprobe being made of a magnetic material, the microprobe having a needle-like tip; anda moving mechanism capable of moving said microprobe toward and away from said specimen and brought to a stop. 2. An electron microscope equipped with a magnetic microprobe as set forth in claim 1, wherein there is further provided a biprism for producing interference between the electron beam transmitted through said specimen and an electron beam passing through a vacuum, and wherein a holographic image of said specimen may be obtained by accepting data about an image created by the electron beam transmitted through said biprism and performing given image processing on the accepted data. 3. An electron microscope equipped with a magnetic microprobe as set forth in claim 1, wherein said image of said specimen is processed to obtain a Lorentz image. 4. An electron microscope equipped with a magnetic microprobe as set forth in claim 1, wherein said magnetic microprobe uses a permanent magnet. 5. An electron microscope equipped with a magnetic microprobe as set forth in claim 1, wherein said magnetic microprobe uses an electromagnet and has a mechanism for varying the strength of a produced magnetic field. 6. An electron microscope equipped with a magnetic microprobe as set forth in claim 1, wherein said moving mechanism uses as its power source an electric motor or piezoelectric device. 7. An electron microscope equipped with a magnetic microprobe as set forth in claim 1, wherein said specimen is carried on a drive mechanism for driving the specimen in the X-, Y-, and Z-directions, and wherein said microprobe is carried on a drive mechanism for driving the microprobe in the X-, Y-, and Z-directions.
056407025	summary	BACKGROUND OF THE INVENTION Immense quantities of waste materials have accumulated at Federal laboratories throughout the United States, and in other countries as well, as a result of the large amount of nuclear research in preparation of fissionable materials for atomic bombs including for use during World War II; in improvement of efficiency and recovery techniques of fissionable materials and fission fragments; and in development of uses for radioactive elements in industry, medicine, and commercial use. In many cases, the equipment used in handling these materials has been contaminated. Safety equipment used to prevent exposure of personnel to the radiation has also been contaminated. Because of this contamination, all of this equipment has been discarded. This, despite that fact that the actual contamination level is extremely low. As a result of this situation, in many cases tons of material have been discarded which has been contaminated with a few microcuries of radioactivity. The ultimate result of all this is that there are literally millions of cubic yards of slightly contaminated materials which must be treated in order to reduce the sheer volume of material which must be stored in a permanent repository. In addition to these slightly contaminated waste materials, there are also huge volumes of liquids and solids which may include some chemicals which are hazardous to human health, which may contain small or large quantities of radioactive materials. These may consist of animals which have been injected with radioactive chemicals; solutions of radioactive species used in experiments; mill tailings from radioactive ore beneficiation; tagged chemicals, and many others. The entire problem is exacerbated by the fact that many of these materials were mixed indiscriminately when they were discharged, so that now there is no convenient way to separate the merely hazardous or radioactive from the non-hazardous or non-radioactive waste. The present invention relates generally to a method of and system for reducing the gross volume of these contaminated wastes by exposing them to the surface of molten metallic aluminum. This metal can be pure aluminum metal, alloys, or eutectic mixtures of other metals which may be either more or less reactive than the aluminum. Such metals may include sodium, potassium, calcium, magnesium, lead, iron, zinc, copper, etc. A number of successful approaches have been proposed by applicant for treating waste products. Some of these approaches are described in U.S. Pat. Nos.: 4,469,661; 4,552,667; 4,559,141; 4,666,696; and 4,695,447 and relate to the destruction of a variety of waste products, including biological waste products; hazardous waste containing organic compounds having covalently bound oxygen, nitrogen, sulfur or phosphorus; inorganic compounds which contain heavy metals or particular hazardous anionic groups or which are hazardous nonmetal oxides or sulfides; pathological materials; and hazardous halogenated hydrocarbon non-radioactive materials. For instance, U.S. Pat. No. 4,469,661, describes a system for treating solids contaminated with polychlorinated biphenyl (PCB) and other hazardous halogenated hydrocarbons which are reacted with molten aluminum. Because of this reaction, chlorine will be abstracted from the organic materials, since aluminum chloride is formed which is a volatile salt that may be distilled from the reaction mixture. In this patented process, there is a direct reaction of the liquid PCB; the passage of PCB-contaminated oils or solvents through the reactor so that the PCBs react, and the oils are distilled from or carbonized in the reactor; or the extraction of PCBs from soil or other contaminated materials with a suitable high-boiling hydrocarbon solvent and subsequent passage through the reactor. Still another approach is set forth in the U.S. Pat. No. 4,552,667 which patent describes a system for disposing of both liquid and solid hazardous wastes of the type including organic compounds which contain covalently bound oxygen, nitrogen, sulfur and/or phosphorus. In this approach, both liquid and solid hazardous wastes are pumped from a tank through a vat of molten aluminum wherein reacting vapors rise from the reaction zone into a water trap arrangement. While these approaches are successful, there is nevertheless a continuing desire to improve upon their applicability and performance, especially from the standpoint of handling radioactivity. For instance, there is a continuing desire to economically reduce the volumetric amounts of waste materials generated at nuclear industrial or research sites; these wastes contain mixtures of various waste materials some of which are hazardous by reason of their radioactivity and others are hazardous by virtue of their nature. Such wastes include, for example, the radio-nuclides on wiping tissues which are saturated with chlorinated solvents; others are inorganic nuclides in the presence of solvents; some are radioactively labeled compounds. It will be appreciated that the volume of such wastes increases daily as research and nuclear power generation activities continue. Given the excessive damages that can arise from accidental discharge of pollutants, it can be extremely expensive to safely and legally dispose of such wastes. To minimize pollution problems, these hazardous and radioactive wastes must be treated and disposed of in accordance with stringent guidelines. Prior efforts have not provided an entirely satisfactory and economical approach to reducing the volume of mixtures of wastes. For instance, at nuclear sites, the radioactive wastes are and have been stored in special containers and it is possible that such containers can include a variety of contaminants (including PCBs) in addition to radioactive contaminants. In order to safely dispose of the contents of such containers, especially older containers, an analysis of each is usually undertaken. The costs of such inspections can be extremely expensive--if not prohibitive--considering the large quantities of these containers which must be tested for proper disposal. SUMMARY OF THE INVENTION It is an object of the present invention to overcome shortcomings of the prior art and improve upon known waste disposal systems and methods. It is another object of the invention to provide a system and method which are highly versatile since they can handle various mixtures of wastes. It is another object of the present invention to reduce the contaminated wastes with a versatile method and system which allow the final disposable product to take such forms, so as to enhance waste disposal by reducing the volume of the final disposable product. It is still another object of the present invention to provide a versatile system and method in which the physical form of the final disposable product can be regulated by reaction with the molten reduction metal, whereby the final disposable product can be alloyed in molten metal, entrapped in the molten metal or removed as slag. According to the present invention there is in one aspect provided a method of reducing the volume of liquid or solid contaminated waste materials. It includes the steps of: a) directing liquid or solid contaminated waste materials to a molten reducing metal reaction chamber; b) applying a reduction metal in molten form so as to contact the contaminated solid or liquid waste materials, entraining them; and, c) removing from the reaction chamber at least a portion of unreacted molten metal containing the products of reaction of the reacted waste materials to allow them to solidify; thereby producing a substantially less hazardous, less voluminous, or innocuous final product which is easily and safely disposable. This method further comprises removing gaseous reaction products from the reaction chamber and passing them through a trap system, after which they are flared off to the atmosphere. Also, the directing steps of the method include: a) directing liquid, solid, or gaseous contaminated waste materials to the reaction chamber; b) directing the molten metal to the reaction chamber in such a way as to maximize contact between the metal and the contaminated waste; c) directing the gaseous reaction products to a suitable separator system outside the reaction chamber; d) directing the molten aluminum, with its burden of solid and alloyed reaction products, into a chamber where the oxides of reaction products can be removed; e) directing the remaining molten metal to a means by which it can be recirculated into the reaction chamber to react with more contaminated wastes, thereby comprising a continuous process. In this manner, the reaction products formed from the contaminants can be removed in solid form, as slag or dross forms and gaseous forms, depending upon the chemical nature of the waste materials and the products. A physical state that can be regulated is the vapor pressure of some of the more volatile elements. Thus, raising the temperature above the boiling point of an element can result in its vaporizing over to a trap. In an illustrated embodiment, the applying step includes applying liquid aluminum to effect the chemical reduction of the contaminated waste and entrainment of the reaction products. Specifically, the liquid or solid waste contaminants are contacted with the liquid aluminum, as by a showering of the contaminated wastes with the liquid aluminum. According to the invention a system is provided for reducing the volume of liquid, gaseous or solid contaminated waste materials, or any mixture of gaseous, liquid or solid waste materials. In essence, the system comprises means for directing gaseous, liquid or solid contaminated waste materials to a molten reducing metal reaction chamber; molten reducing metal reduction chamber means operable for reacting with the contaminated materials; means for applying a reduction metal in molten form so as to contact the contaminated solid, liquid or gaseous waste materials in the reaction chamber means; thereby chemically reducing the contaminated waste materials; and, means for removing at least a portion of reacted molten metal and the reacted products of waste materials from the reaction chamber so as to allow them to solidify thereby producing a substantially less hazardous or innocuous final product which is easily and safely disposable and occupies substantially less volume. Dilution by the unreacted metal may make it possible to dispose of it as a "low-level" waste. In an illustrated embodiment, the removing means includes a trap assembly, wherein the trap assembly removes condensable materials which are vapors at the temperature of molten metal, as they are swept from the reaction chamber by the gaseous reaction products. In another aspect, the applying means may be operable for applying liquid reducing metal such that the liquid, solid, or gaseous waste contaminants are contacted with the liquid reducing metal. In another aspect, the liquid, solid or gaseous contaminated wastes may be showered with the liquid reducing metal. Other objects and further scope of applicability of the present invention will become apparent when taken in conjunction with the accompanying drawing.
061750514	summary	FIELD OF INVENTION This invention relates generally to remediation of nuclear reactor wastes, and more specifically, to deactivation of metal liquid coolants used for absorbing and transferring heat in nuclear reactors. BACKGROUND OF THE INVENTION Nuclear facilities at the end of their useful lives cannot merely be abandoned. As such, to protect the public from remaining hazardous materials the site must be decommissioned which includes decontamination, dismantling and demolition with subsequent return to green field status. Usually the first stage in nuclear plant decommissioning is the removal of fuel, followed by the initial wash out of the coolant system and then in situ decontamination for removing residual active species before dismantling the facility. In the process of decommissioning a breeder nuclear reactor, the liquid metal coolant, which may be an alkali metal such as sodium or a sodium-potassium alloy, presents unthoughtof problems for disposal. Liquid sodium and/or sodium/potassium alloys are extremely reactive metals subject to highly exothermic reactions with water which may result in the generation of hydrogen gas. Accordingly, when liquid alkali metal coolants are involved in the decommissioning of a nuclear reactor additional precautions must be taken for disposing of the large quantities of alkali metal wastes. In a breeder nuclear reactor a liquid metal coolant is used in several different areas but always for its cooling and/or heat transferring capabilities. The core of the reactor which contains the fuel element pins and the uranium-238 blanket surrounding the core are cooled by liquid metal coolant which circulates in two separate and distinct coolant loops, namely the primary and secondary or intermediate loop. The primary and secondary loops are isolated from each other to reduce the transfer of radioactive isotopes between the loops. The primary coolant loop surrounds the fuel core for absorbing heat from fission activity within the core and this coolant may contain radioisotopes of the liquid metal due to absorption of neutrons. The coolant enter the primary loop at about 600.degree. F. and leaves the core at about 900.degree. F. This absorbed heat retained by the molten alkali metal in the primary loop is transferred to the secondary or intermediate coolant loop by means of a heat exchanger. An estimated 75,000 gallons of liquid alkali metal coolant must be drained from the combined coolant loops and the liquid metal deactivated. After the initial draining of the molten liquid coolant, the primary and secondary loops and any additional equipment have to be decontaminated in situ. In this regard, any scale or deposits of remaining solidified alkali metal need to be dissolved and removed from the coolant system. Additionally, alkali metal especially sodium bonded fuel found within spent fuel elements must be deactivated. Fuel elements used in breeder reactors include uranium-235 pencil like pellets that are inserted into a thin-walled stainless steel tube. Included in these tubes is a small amount of an alkali metal, such as sodium which functions as a heat-transfer agent. The tube is welded shut and as more and more of the uranium-235 undergoes fission, fissures develop in the fuel allowing the alkali metal to enter the voids. The sodium extracts an important fission product, namely cesium-137, and hence become intensely radioactive. The liquid alkali metal drained and removed from the coolant system and/or removed from spent fuel elements must be disposed of in a safe and secure manner. However, before final disposal, the alkali metals must be deactivated, especially sodium, to reduce its reactivity. Several methods have been suggested for treating the sodium or sodium-potassium alloy to deactivate before disposal. U.S. Pat. No. 4,032,614 discloses a method for contacting molten alkali metal with a caustic solution thereby forming an alkali metal hydroxide. However, this method is carried out at increased temperatures with a concomitant production of hydrogen gas. The high temperatures used in this process increase the possibility of a hydrogen explosion thereby presenting an additional safety hazard. Furthermore, the method produces large quantities of caustic material which is considered hazardous due to its corrosivity. As such, disposal becomes a problem because the Environmental Protection Agency considers this caustic material as "mixed waste" due to its hazardous characteristics and radioactive content. Accordingly, the caustic material has to be disposed of in a hazardous waste site. Still further, this method has the limitation of not being applicable for dissolving and removing any deposited alkali metal remaining on process equipment, tools or in the circuit loops of the reactor. U.S. Pat. No. 5,678,240 overcomes the problems presented when producing alkali metal hydroxides by further converting the caustic waste materials to alkali metal carbonates. This method eliminates the concern for disposal of hazardous corrosive materials but includes several steps that involve the initial conversion to a hydroxide. As such, concerns for generating explosive hydrogen gas is still applicable. Furthermore, this method may not be used for final wash out of a reactor's coolant systems to remove any remaining scale or solids. Accordingly, a need exists for improved methods for deactivation of metal coolants removed from a nuclear reactor that reduces the production of explosive hydrogen gas and/or hazardous caustic materials, do not leave solid deposits and residue on process equipment after deactivation and may be used in a final in situ decontamination of a reactor's coolant systems. SUMMARY OF THE INVENTION Terms For purposes of this invention, the terms and expressions below, appearing in the specification and claims, are intended to have the following meanings: "Precipitating agent" as used herein means a compound that ionizes in an ammoniacal liquid such as anhydrous liquid ammonia to form an anion that combines with an alkali or alkaline earth metal cation to form a alkali or alkaline earth metal salt. "Breeder Reactor" as used herein means a nuclear reactor wherein the amount of plutonium produced exceeds the amount of plutonium consumed. "Precipitating ammoniacal mixture" as used herein is a mixture containing a precipitating agent dissolved and ionized in an ammoniacal liquid. "Metal coolants" as used herein means alkali and alkaline metals and mixtures thereof, either in a liquid or solid state, that have been used as circulating liquid coolant in a nuclear reactor or as heat transfer agents included within fuel element tubes. These metal coolants or heat transfer agents may contain other contaminates such as radioactive materials. "Ammoniacal liquid" as used herein means solutions having an ammonia content ranging from at least 50 percent-by-weight of ammonia in water to anhydrous liquid ammonia. Accordingly, it is a principal object of the present invention to provide improved methods for deactivating alkali metals used as liquid coolant in nuclear reactors that are safe and efficient without generating large quantities of caustic hazardous material and/or hydrogen gas. Yet another object of the invention is to provide a method for removing solidified metal coolant residue from process equipment, tools and/or in primary and secondary circuit loops of a nuclear reactor's cooling system. Still another object of the present invention is to provide a method of deactivating metal coolants such as alkali metals at lower temperatures to substantially reduce the possibility of an explosion of any hydrogen gas that may be generated during the deactivation process. A further object of the present invention is to provide a method for deactivating alkali metals removed from a reactor system to generate a solid non-hazardous waste product that can be landfilled in a sanitary landfill or stored as low level radioactive waste in a disposal site. A still further object of the present invention is to provide a method that not only deactivates liquid alkali metals removed from a breeder reactor but also detoxifies hazardous materials thereby rendering both the liquid alkali metal and hazardous waste as a non-hazardous waste stream. Yet another object of the present invention is to provide a method for deactivation of alkali metals removed from or included within spent fuel elements. These and additional objects are provided by the processes of the present invention which are directed to the deactivation of metal coolants removed from nuclear reactor coolant systems. A liquid alkali or alkaline earth metal can be deactivated by combining with a precipitating agent, both of which are soluble in liquefied ammonia to form a precipitating compound. Particularly, sodium and sodium-potassium alloys can be deactivated by contacting the alkali metal with an excess of an ammoniacal liquid such as anhydrous liquid ammonia to form a reaction mixture which when combined with a precipitating agent that substantially dissolves and ionizes in the ammoniacal liquid forms an alkali metal salt precipitate. The reaction mixture comprises a solution of solvated alkali metal cations and electrons that combine with an ionizable compound for precipitating an alkali metal salt. The resulting alkali metal salt precipitate may have a reduced solubility in the ammoniacal liquid when compared to that of the original precipitating agent and alkali metal thereby providing for easy separation of the precipitate from the ammonia solution. In one preferred embodiment of the invention, the process comprises the step of combining two mixtures, a reaction mixture comprising an alkali metal coolant removed from a reactor, either in solid or liquid form, introduced into a reaction vessel containing an ammoniacal liquid such as anhydrous liquid ammonia wherein the alkali metal is solubilized thereby forming alkali metal cations and solvated electrons. The alkali metal is introduced into the reaction mixture in an amount not exceeding the solubility of the alkali metal in the ammoniacal liquid ammonia. A precipitating ammoniacal mixture comprising a precipitating agent solubilized and/or ionized in anhydrous liquid ammonia is combined in the reaction vessel with the solvated alkali metal cations and electrons. The combining of ions in the reaction vessel forms an alkali metal salt which may be removed from the reaction vessel. The anhydrous liquid ammonia may be evaporated from the reaction vessel and recovered for future use. The processes of the present invention further contemplate in situ deactivation and recovery of solidified metal coolant from surfaces of a reactor coolant system, process equipment, tools and any other surfaces encrusted with solidified alkali or alkaline earth metal. Accordingly, in a preferred method an ammoniacal liquid such as anhydrous liquid ammonia is circulated through the coolant system, that being the primary and secondary loops and any other loops or surfaces exposed to the liquid metal coolant, to dissolve any remaining metal liquid coolant that solidified as a scale and/or became trapped in the coolant system after initial drainage of the molten metal. The anhydrous liquid ammonia is pumped through the coolant system under pressure to maintain the anhydrous ammonia in a liquefied state. The anhydrous liquid ammonia is circulated until a sufficient amount of the solidified metal, such as alkali metal is dissolved in the liquid ammonia and then removed from the coolant system. Upon removal from the system, the ammonia solution comprising solvated alkali metal cations and electrons is combined with a precipitating agent that solubilizes and ionizes in ammoniacal liquid. The combined mixtures effect the precipitation of an alkali metal salt. The present processes provide significant advantages over prior art methods, in that, the final waste product may be an alkali or alkaline earth metal salt which is not considered a hazardous material. In fact, liquid alkali metal circulating in the secondary loop of a reactor's cooling system is usually considered non-radioactive, assuming there has not been a leak between the primary and secondary circuit, and the precipitated alkali metal salt can be disposed of in a non-RCRA controlled landfill. Additionally, the process may be utilized for in situ decontamination which dissolves and removes solidified alkali metal from the coolant system for further treatment with a reagent that yields an alkali metal salt. Still further, because of the lower temperatures in the reaction vessel there is a reduced risk of an accidental explosion of any hydrogen gas that may form during the reaction. Yet another advantage of the present process is the substantial reduction of the production of hydrogen gas by selectively choosing a precipitating agent that has a cation or anion that may be reduced in the reaction mixture by solvated electrons.
	description	The present application claims priority from Japanese Patent application serial no. 2013-169486, filed on Aug. 19, 2013, the content of which is hereby incorporated by reference into this application. Technical Field The present invention relates to a laser welding apparatus, a preventive maintenance method for a reactor internal structure of a nuclear power plant, and a laser cutting apparatus and more particularly to a laser welding apparatus, a preventive maintenance method for a reactor internal structure of a nuclear power plant, and a laser cutting apparatus which are suitably applicable to the nuclear power plant. Background Art Conventionally, in a preventive maintenance operation of a reactor internal of a nuclear power plant, an automatic TIG welding or a laser welding described in Japanese Patent Laid-open No. 2010-276491 and Japanese Patent No. 3469185 is used as a welding method. In each aforementioned welding, a method of melting a wire fed to a welding portion of a welding object using a welding apparatus having a wire feed function or a method of setting a sleeve beforehand in the welding portion and melting it with non-filler is used. High-quality welding can be performed by the TIG welding and the laser welding, though as described in Japanese Patent Laid-open No. 2010-276491 and Japanese Patent No. 3469185, it is necessary to keep the angle of a welding torch relative to the welding surface in a state as close to perpendicular as possible. For this reason, a drive mechanism of a welding apparatus scanner of scanning the welding apparatus needs to include a complicated mechanism for adjusting posture of the welding torch. In contrast, as described in Japanese Patent Laid-open No. 2004-255410, in a head portion ahead of an optical fiber end portion, a laser welding apparatus having the conventional wire feed function, includes a collimate lens for converting the spread laser beam emitted from the optical fiber to a parallel beam and a condensing lens for condensing the parallel beam from the collimate lens. The laser beam enters the optical fiber from a laser oscillator. A laser irradiation arc welding method is described in Japanese Patent Laid-open No. 2006-95559. This laser irradiation arc welding method uses a welding apparatus including an arc welding head and a laser welding head. The laser welding head includes the aforementioned collimate lens and condensing lens. A laser welding head for feeding a powder-shape welding material instead of a wire includes a condensing lens for condensing a laser beam together with a power feed apparatus as described in Japanese Patent Laid-open No. 2007-216235. A powder laser welding head described in Japanese Patent Laid-open No. 2007-216235 and a laser welding head described in Japanese Patent Laid-open No. 2004-255410 and Japanese Patent Laid-open No. 2006-95559 respectively, dispose a collimate lens for converting the spread laser beam emitted from an optical fiber to a parallel beam at the front stage of a condensing lens. The parallel beam enters the condensing lens. A laser welding for feeding a powder-shape welding material is described also in Japanese Patent Laid-open No. 2007-50446 and Japanese Patent Application Publication No. 9(1997)-506039. In a boiling water nuclear power plant, a plurality of control rod drive mechanism housings and a plurality of in-core monitor housings are attached to a bottom head of a reactor pressure vessel passing through the bottom head. Each control rod drive mechanism housing is separately inserted into a plurality of stub tubes attached to the bottom head of the reactor pressure vessel by welding, passes through each stub tube and the bottom head of the reactor pressure vessel, and is attached to each stub tube by welding. Further, each of the in-core monitor housings is also attached to the bottom head of the reactor pressure vessel by welding. Repair operation is performed for the welded portions between the stub tubes and the bottom head of the reactor pressure vessel bottom, the welded portions between the control rod drive mechanism housings and the stub tubes, and the welded portions between the in-core monitor housings and the bottom head of the reactor pressure vessel. The repair operation is an operation in a narrow portion between the stub tubes, between the control rod drive mechanism housings, and between the control rod drive housing and the in-core monitor housing. The repair operation in a narrow portion in the boiling water nuclear power plant using a repair apparatus for the welded portions is described in Japanese Patent No. 4178027 (WO2002/011151). Even in a pressurized water nuclear power plant, a plurality of in-core guide tubes pass through a bottom head of a reactor pressure vessel and each in-core guide tube is attached to the bottom head by welding. The in-core guide tubes correspond to the in-core monitor housings in the boiling water nuclear power plant. Japanese Patent Laid-open No. 2011-52966 (US2011/0051878A1) describes the repair operation in a narrow portion of the in-core guide tubes using the repair apparatus for the welded portion between the bottom head of the reactor pressure vessel and the in-core guide tube, which is performed in the pressurized water nuclear power plant. [Patent Literature 1] Japanese Patent Laid-open No. 2010-276491 [Patent Literature 2] Japanese Patent No. 3469185 [Patent Literature 3] Japanese Patent Laid-open No. 2004-255410 [Patent Literature 4] Japanese Patent Laid-open No. 2006-95559 [Patent Literature 5] Japanese Patent Laid-open No. 2007-216235 [Patent Literature 6] Japanese Patent Laid-open No. 2007-50446 [Patent Literature 7] Japanese Patent Application Publication No. 9(1997)-506039 [Patent Literature 8] Japanese Patent No. 4178027 [Patent Literature 9] Japanese Patent Laid-open No. 2011-52966 [Non Patent literature 1] Itaru Chida et al., Study on Laser Welding Technology of Nuclear Power Plants, Japan Machinery Society Essays (Edition B), Volume 78, No. 787, (2012-3), pp. 73-77 The laser welding can concentrate high-density energy in a very narrow range, so that it can obtain deeper melting than the arc welding and can reduce the heat input quantity. Further, the laser welding uses a high-energy density heat source, so that it can realize high-speed welding. As a result, the laser welding can realize highly-efficient, highly-reliable, and high-quality welding. The repair operation for the welded portion of the reactor internal in the reactor pressure vessel is performed in a high-radiation environment, so that the laser welding, which is capable of obtaining a welded portion whose welding time is short and whose reliability is high, is welding suitable for the repair operation of the welded portion in the reactor pressure vessel. The laser welding using a wire needs to feed a wire to the welding portion melted by the laser. To repair the welded portion of the bottom head of the reactor pressure vessel, the wire is fed from the wire feed mechanism installed on the laser welding head transferred to the bottom head, though loadable wires are limited in the number. Therefore, when the wires loaded on the laser welding head are used up, it is necessary to complement wires to the wire feed mechanism of the laser welding head pulled up and taken out from the reactor pressure vessel and then move the laser welding head down to the neighborhood of the welding portion in the reactor pressure vessel again. In contrast, in the laser welding for feeding a powder-shape metal, which is a filler metal, to the welding portion (hereinafter, for convenience, referred to as powder laser welding) and this laser welding described in Japanese Patent Laid-open No. 2007-50446 and Japanese Patent Application Publication No. 9(1997)-506039, the metallic powder which is the filler metal can be fed continuously to the powder laser welding head through a tube in a state that a laser welding head including a powder feed path is disposed in the neighborhood of the welding portion in the reactor pressure vessel. Therefore, in the laser welding using powder, there is no need to move up and down the powder laser welding head so as to complement wires which are a filler metal, and the time required for the welding operation can be shortened compared with the laser welding using a wire. However, as mentioned above, the powder laser welding head includes a collimate lens and a condensing lens, so that the powder laser welding head becomes longer in length. Thus, the repair welding for the respective welded portions of the control rod drive mechanism housings, the stub tubes, and the in-core monitor housings which are standing together in large numbers on the bottom head of the reactor pressure vessel is difficult. For example, when repairing the welded portion between the control rod drive mechanism housings and the stub tubes and between the stub tubes and the bottom head of the reactor pressure vessel, the powder laser welding head needs to move around overall the peripheries of the control rod drive mechanism housings. However, since the respective intervals between other control rod drive mechanism housings and other stub tubes adjacent to the control rod drive mechanism housings and the stub tubes which are welding object are a narrow portion, it is difficult to make the laser welding head, which is long in length, move around the peripheries of the control rod drive mechanism housings and the stub tubes which are the welding objects facing the narrow portions. An object of the present invention is to provide a laser welding apparatus, a preventive maintenance method for a reactor internal structure of a nuclear power plant, and a laser cutting apparatus capable of easily performing a prevention maintenance operation for a prevention maintenance object of a plant which faces a narrow portion and shortening the time required for the prevention maintenance operation. A feature of the present invention for attaining the aforementioned object are a structure having a welding head including a head body, and a collimate lens installed on the head body and facing an end face of an optical fiber connected to the head body; and a welding head scanning apparatus of scanning the welding head, wherein a laser path of introducing a laser emitted from the optical fiber and passing through the collimate lens is formed in the head body; wherein the welding head includes only the collimate lens as a lens; and wherein a laser outlet of the laser path is formed in an end portion of the head body. The welding head includes only the collimate lens as a lens but includes no condensing lens, so that length of the welding head can be shortened and the welding head is made compact. Therefore, when the welding head moves in a narrow portion, the welding head can be avoided from interference to a structural member other than the welding object. As consequence, the laser welding to the welding object by the welding head can be performed easily, and the time required for the welding operation can be shortened. Namely, the laser welding which is a prevention maintenance operation to the welding object which is a prevention maintenance object can be performed easily and the time required for the prevention maintenance operation can be shortened. Preferably, it is desired to form the powder feed path of introducing the metallic powder which is a filler metal in the head body and form an injection outlet of the powder feed path in the end portion of the head body. The welding head forming the powder feed path is made compact. Therefore, when the welding head moves in a narrow portion, the welding head can be further avoided from interference to a structural member other than the welding object, and the laser welding using powder to the welding object by the welding head can be performed easily, and the time required for the welding operation can be further shortened. Namely, the laser welding which is a prevention maintenance operation using powder to the welding object which is a prevention maintenance object can be performed easily and the time required for the prevention maintenance operation can be further shortened. The aforementioned object can be attained also by a structure having a cutting head including a head body, and a collimate lens installed on the head body and facing an end face of an optical fiber connected to the head body; and a cutting head scanning apparatus of scanning the working head, wherein a laser path of introducing a laser emitted from the optical fiber and passing through the collimate lens and a gas feed path are formed in the head body; wherein the cutting head includes only the collimate lens as a lens; and wherein a laser outlet of the laser path and a gas outlet of the gas feed path are formed in an end portion of the head body. The cutting head includes only the collimate lens as a lens but includes no condensing lens, so that length of the cutting head can be shortened in length and the cutting head is made compact. Therefore, when the cutting head moves in a narrow portion, the cutting head can be avoided from interference to a structural member other than the welding object. As consequence, the cutting operation to the cutting object by the cutting head can be performed easily, and the time required for the cutting operation can be shortened. Namely, the laser cutting operation which is a prevention maintenance operation to the cutting object which is a prevention maintenance object can be performed easily and the time required for the prevention maintenance operation can be shortened. According to the present invention, the prevention maintenance operation for the prevention maintenance object of the nuclear power plant which faces a narrow portion can be performed easily and the time required for the prevention maintenance operation can be shortened. The inventors reviewed a countermeasure of shortening the length of a laser welding head to enable welding for a welding object facing a narrow portion. Before reviewing the countermeasure, the inventors conducted a welding test in order to confirm the validity of the powder laser welding applied to maintenance welding of a reactor internal in a reactor pressure vessel. An example of the welding test will be explained by referring to FIG. 7. As described in Japanese Patent No. 4178027, many control rod drive mechanism housings, stub tubes, and in-core monitor housings are attached to a bottom head of a reactor pressure vessel of a boiling water nuclear power plant, that is, a bottom of the reactor pressure vessel by welding. The stub tube positioned on an outermost periphery which is attached to the bottom is at an angle of approximately 45° relative to the bottom of the reactor pressure vessel. Further, many in-core guide tubes are attached by welding on a bottom of a reactor pressure vessel of a pressurized water nuclear power plant as described in Japanese Patent Laid-open No. 2011-52966. The in-core guide tube positioned on an outermost periphery is also at an angle of approximately 45° relative to the bottom of the reactor pressure vessel. As mentioned above, in the boiling water nuclear power plant and the pressurized water nuclear power plant, when the attaching angle of a tubular structure (for example, a stub tube, a control rod drive mechanism housing, an in-core monitor housing, or an in-core guide tube) which is an reactor internal attached to the bottom of the reactor pressure vessel by welding becomes less than or equal to 50° and the laser welding head is fixed in one direction, if the welding object can be welded at an angle of 0° (perpendicular) to 60° between the surface which is the welding object and the laser welding head, the welding of the tubular structure attached to the bottom of the reactor pressure vessel can be covered. The outline of the welding test that was conducted to check the weldability of the powder laser welding for an inclined surface of a welding test material is shown in FIG. 7. In the welding test, the weldability was checked within the angle range from 0° (perpendicular) to 60° relative to a plane of the welding test material. The welding test material is made from low alloy steel or an Inconel material used for the bottom of the reactor pressure vessel and an Inconel material was used for the metallic powder which is a filler metal. For the welding test conditions, laser power P was set within a range from 300 W to 4000 W, and a laser spot diameter D was set within a range from 1.4 mm to 5.4 mm, and the welding speed was set within the range from 9 cm/min to 300 cm/min, and a metallic powder feed rate M was set within a range from 0 g/min to 63 g/min. The welding test was conducted both for the laser welding under the non-filler condition of feeding no metallic powder and for the laser welding of feeding metallic powder. The results obtained by these welding tests will be explained below by referring to FIGS. 8 to 11. The results obtained by the laser welding test under the non-filler condition of feeding no metallic powder are shown in FIGS. 8 and 9 and the results obtained by the laser welding test of feeding metallic powder are shown in FIGS. 10 and 11. In the welding tests, the longitudinal section of each welding surface was observed. In the laser welding under the non-filler condition, when the longitudinal section of each welding test material was melted, it was decided as passing and when the longitudinal section was not melted, it was decided as failure. In the welding test results, the rate of the number of passed welding test materials to the total number of welding test materials was summarized as a pass rate (%). Also in the test results when the metallic powder is fed, similarly, the longitudinal section of each welded surface was observed. When satisfactory penetration was obtained, it was decided as passing, and when lack of fusion was observed, it was decided as failure, and then the results were summarized by a pass rate. The results obtained by the laser welding test under the non-filler condition and the results of the laser welding test for feeding the metallic powder, were arranged based on the heat input (kJ/cm) described in Itaru Chida et al., Study on Laser Welding Technology of Nuclear Power Plants, Japan Machinery Society Essays (Edition B), Volume 78, No. 787, (2012-3), pp. 73-77 and based on the power density (W/mm2) obtained by the research results on the laser welding technology of the nuclear power plant by the inventors, respectively. The test results of the laser welding performed under the non-filler condition which are arranged by the heat input are shown in FIG. 8 and the test results of the laser welding performed under the non-filler condition which are arranged by the power density are shown in FIG. 9. In addition, the test results of the powder laser welding arranged by the heat input are shown in FIG. 10 and the test results of the powder laser welding arranged by the power density are shown in FIG. 11. In the test results of the laser welding performed under the non-filler condition which are arranged by the heat input (refer to FIG. 8), the pass rate of the welding to the heat input (kJ/cm) at the time of welding is varied. For example, the pass rate is 100% at 0.3 kJ/cm which is low heat input, and the pass rate shows such a low value as 0% at 1.8 kJ/cm which is high heat input. As mentioned above, when the test results of the laser welding performed under the non-filler condition are arranged by the heat input, a fixed tendency cannot be found between the heat input and the pass rate. On the other hand, when the test results of the laser welding performed under the non-filler condition are arranged by the power density (W/mm2) at the time of welding (refer to FIG. 9), if the power density is set to 42 W/mm2 or higher, it is found that the welding pass rate can be maintained at 100%. Even in the test results of the laser welding for feeding metallic powder to the welding place, the similar tendency to the laser welding performed under the non-filler condition is seen. When arranged by the heat input of the welding, the welding pass rate is varied (refer to FIG. 10) and when arranged by the power density at the time of welding, if the power density is set to 27 W/mm2 or higher, it is found that the welding pass rate can be maintained at 100% (refer to FIG. 11). According to the aforementioned test results, when the laser power is set within the range from 300 W to 4000 W, the laser spot diameter is set within the range from 1.4 mm to 5.4 mm, and the welding speed is set within the range from 9 cm/min to 300 cm/min, and when the metallic powder feed rate is set within the range from 0 g/min to 63 g/min, if the power density is adjusted to 42 W/mm2 or higher, that is, to laser power P satisfying P>10.5 πD2, both of the non-filler laser welding and the laser welding for feeding metallic powder can perform good laser welding at a pass rate of 100% within the angle range between the central axis of the laser welding head and the welding surface from 0° to ±60°. Here, D indicates a spot diameter of the laser. In addition, the feed rate of the metallic powder which is a filler metal to the fusion zone of the welding portion is conventionally shown by [g/min] which is a metallic powder feed rate M (g) fed per unit time (min). When the above-mentioned test results of the powder laser welding are arranged based on the conventional arranging method, that is, the arranging method by [g/min] which is a metallic powder quantity M per unit time, the feed rate of the metallic powder to the fusion zone of the welding portion is shown by 1.63 g/min to 63.3 g/min. However, when the feed rate of the metallic powder to the fusion zone of the welding portion is arranged by the relation (g/kW·s) of the laser beam power P (kW), the irradiation time t (s), and the metallic powder feed rate M (g), the feed rate of the metallic powder in the powder laser welding test of this time can be arranged within a limited range from 0.1 g/kW·s to 0.26 g/kW·s. The inventors found that if the feed rate M of the metallic powder is adjusted to 0.26 g/kW·s or lower, that is, to the condition satisfying [M<0.26×P×t] based on the test results of the powder laser welding executed at this time, build-up welding can be performed. The laser welding using metallic powder (hereinafter, as mentioned earlier, for convenience, referred to as the powder laser welding) was performed and then the appearance of the welding test materials was checked. As a result, non-welded metallic powder was found adhered on a bead surface of the welding portion and a rough feel was confirmed, so that the bead surface with non-welded metallic powder adhered to was subjected again to the melting process with non-filler using the laser from the laser welding head (hereinafter, for convenience, referred to as the powder laser welding head) including a powder feed path. After the melting process, the bead surface was checked by penetrant inspection, thus no defects were observed. By the aforementioned welding test results, it became clear that in the powder laser welding, the angle between the central axis of the powder laser welding head and the welding surface can be set within the range of ±60° with the perpendicular line of the welding surface; and the angle adjustment of the powder laser welding head with a tubular structure such as the stub tube and the in-core monitor housing (or the in-core guide tube) which are positioned in a narrow portion inside the bottom of the reactor pressure vessel can be performed far more easily than the angle adjustment of the laser welding head for making the angle relative to the welding surface as close to perpendicular as possible in the conventional wire feed laser welding. Further, it became clear that the operation time required for the powder laser welding can be shortened extensively by adjusting the laser power P so as to satisfy P>10.5 πD2 and further adjusting the feed rate M of the metallic powder so as to satisfy M<0.26×P×t as knowledge by the aforementioned powder laser welding test. Next, the interference of the powder laser welding head to a tubular structure, that is a tubular member (for example, a stub tube, a control rod drive mechanism housing, or an in-core monitor housing) was investigated in the case of applying the powder laser welding to the welding portion of the tubular structure. The inventors investigated the interference thereof by assuming that the welding can be performed when the angle between the powder laser welding head and the welding surface is within the range of ±60° as a result of reflecting the aforementioned test results of the powder laser welding. The conventional powder laser welding head includes a collimate lens and a condensing lens similarly to the laser welding head described in Japanese Patent Laid-open No. 2004-255410 and Japanese Patent Laid-open No. 2006-95559. The total length of the conventional powder laser welding head is 760 mm, for example, in the powder laser welding head for outputting a 4000 W laser beam. As described in Japanese Patent No. 4178027, for example, it is assumed to repair the welded portion between one stub tube attached to the inner surface of the bottom of the reactor pressure vessel of the boiling water nuclear power plant and the bottom by using the powder laser welding head with a total length of 760 mm. To repair the welded portion between the stub tube and the bottom of the reactor pressure vessel, the powder laser welding head is disposed in the reactor pressure vessel so that the angle of the welding surface of the welding portion relative to the central axis of the powder laser welding head falls within the range of ±60°, and furthermore, the powder laser welding head needs to be rotated over the entire periphery of the welding portion. However, when intending the conventional powder laser welding head with a total length of 760 mm to rotate around the stub tube to be welded, the rotating powder laser welding head interferes with another stub tube adjacent to the stub tube that is a welding object and the control rod drive mechanism housing attached to the stub tube. Thus, the powder laser welding head cannot rotate around the stub tube that is the welding object, and repairing of the welded portion being a repair object becomes difficult. To avoid interference with the adjacent stub tube that occurs when rotating the powder laser welding head, it is effective to shorten the length of the powder laser welding head. Therefore, the inventors investigated shortening the length of the powder laser welding head. As described in Japanese Patent Laid-open No. 2004-255410 and Japanese Patent Laid-open No. 2006-95559, the laser welding head used by the conventional laser welding includes a collimate lens and a condensing lens. The laser beam spread state in the laser welding head having an optical system including the collimate lens and condensing lens is shown schematically in FIG. 12. The laser emitted from the optical fiber and converted to a parallel beam by the collimate lens passes through the condensing lens and then is converged on a focal position of the condensing lens. When welding by using the laser passing through the condensing lens like the conventional laser welding head, if coming off the focal position of the condensing lens, the laser diameter at either of the position closer to the condensing lens side than to the focal position and the position on the welding member side from the focal position becomes larger than the laser diameter at the focal position and the laser power density (W/mm2) at either of the former position and the latter position becomes smaller than the laser power density at the focal position. Therefore, in the laser welding of the wire feed system, the distance between the condensing lens and the welding surface needs to be adjusted so as to fit to the focal distance of the condensing lens. In contrast, in the powder laser welding, if the metallic powder fed to the fusion zone of the melding surface generated by the laser irradiation is melted, the welding member can be welded. Therefore, the inventors considered that even when the powder laser welding head including the condensing lens is used, the welding using the metallic powder is possible without fitting the distance between the condensing lens and the welding surface strictly to the focal distance of the condensing lens. Therefore, the inventors performed the powder laser welding test by the powder laser welding head having a focal lens using metallic powder with a particle diameter of 63 to 212 μm and they find that powder laser welding obtaining a pass rate of 100% is possible so long as the power density is 27 W/mm2 or higher even if the distance between the focal lens and the welding surface is off the focal distance of the focal lens. The inventors performed the powder laser welding on the welding surface, for example, under the conditions of using a powder laser welding head including the condensing lens, shifting and setting the distance between the condensing lens and the welding surface within a range from −6 mm to 30 mm for the focal distance of the condensing lens, inclining the central axis of the powder laser welding head at 50° to the welding surface, and setting the power density at 112 W/mm2. The inventors checked the welded surface after end of the powder laser welding and, as mentioned above, they were successful in melting the metallic powder on the welding surface even though the distance between the condensing lens and the welded surface was shifted from the focal distance of the condensing lens within the range from −6 mm to 30 mm. On the basis of the results, the inventors confirmed that the metallic powder fed to the welding surface can be melted and powder laser welding at a pass rate of 100% is possible even when the condensing lens is deleted and only the collimate lens is used as a lens of the optical system of the powder laser welding head. The condensing lens is deleted, thus the length of the powder laser welding head can be shortened. Namely, the total length of the powder laser welding head with the condensing lens deleted can be shortened to the extent that, when rotating the powder laser welding head around the welding portion of one stub tube, the head does not interfere with the adjacent stub tube, control rod drive mechanism housing, or in-core monitor housing. The powder laser welding head using only the collimate lens as a lens can easily rotate around the welding portion of one stub tube. The laser beam spread state in the powder laser welding head using only the collimate lens as a lens is shown schematically in FIG. 13. In the powder laser welding head, the laser spot diameter passing through the collimate lens is almost constant and does not change until reaching the welding surface. The welding using the laser has been described so far. Meanwhile, the inventors found that the optical system used for the powder laser welding head for using only the collimate lens as a lens can be applied to a laser cutting apparatus used for laser cutting work. The inventors executed the laser cutting work test by changing the power density in the same way as the powder laser welding, that is, under the conditions of power densities of 42 kW/mm2 and 56 kW/mm2. The laser power density used for cutting needs to be larger than the laser power density used for the aforementioned laser welding. At 42 kW/mm2, stainless steel with a sheet thickness of 0.5 mm can be cut at a cutting speed of 1100 mm/s or lower and at 56 kW/mm2, it can be cut at a cutting speed of 1300 mm/s or lower. When the obtained results are arranged by power density (W/mm2)/cutting speed (mm/s2) based on the above test results, the structure member can be cut by the laser at the time of 43 W·s/mm or higher. Therefore, when the power density of the parallel laser beam generated by passing through the collimate lens is set to 42 kW/mm2 or higher, it is desirable to set the cutting work condition by the laser to 43 W·s/mm or higher. This numerical value indicates the product of the irradiation laser power and the irradiation time per unit volume of a cutting work object. The embodiments of the present invention reflecting the above investigation results will be explained below. A prevention maintenance method of a reactor internal of a nuclear power plant according to embodiment 1 which is a preferred embodiment of the present invention will be explained below by referring to FIGS. 1 and 2. The prevention maintenance method of the reactor internal of the present embodiment is applied to a reactor internal existing in a reactor pressure vessel of a boiling water nuclear power plant. In the prevention maintenance method of the reactor internal of the nuclear power plant of the present embodiment, a laser welding apparatus 10 shown in FIG. 3 is used. The laser welding apparatus 10 is provided with a powder laser welding head (welding head) 21, a welding head scanning apparatus 23, and a metallic powder feed apparatus 41. The powder laser welding head 21 includes a head body 22 and a lens housing 24 as shown in FIG. 3. The lens housing 24 connected to one end portion of optical fiber 26 is disposed in a head body 28 and a collimate lens 25 is installed in the lens housing 24 so as to face one end of the optical fiber 26. A laser path 27 which is an opening portion formed from the lens housing 24 toward one end of the head body 22 is formed in the head body 22. The laser path 27 has openings at its both ends. The first opening of the laser path 27 is opposite to the collimate lens 25. The second opening of the laser path 27 is a laser outlet and is formed in an end face of the head body 28. The lens housing 24 and the laser path 27 are arranged along the central axis of the head body 22. Another end portion of the optical fiber 26 is connected to a laser oscillator (not shown). The powder laser welding head 21 includes only the collimate lens 25 as a lens but includes no condensing lens. Three powder feed paths 29A, 29B, and 29C (refer to FIG. 5) are formed in the head body 22. FIG. 4 does not show the powder feed path 29C. Each of the powder feed paths 29A, 29B, and 29C is inclined toward an extended line of a central axis of the laser path 27 at the end portion of the head body 22, the end portion including the laser outlet. The respective powder injection outlets of the powder feed paths 29A, 29B, and 29C are formed in the end face of the head body 22 with the laser outlet of the laser path 27 formed. The distance between the center of the powder injection outlet of the powder feed path 29B and the center of the laser outlet is the same as the distance between the center of the powder injection outlet of the powder feed path 29A and the center of the laser outlet. A powder feed hose 30A is attached to the head body 22 by a fixing member 32A and the powder feed hose 30A is connected with the powder feed path 29A. A powder feed hose 30B is attached to the head body 22 by a fixing member 32B and the powder feed hose 30B is connected with the powder feed path 29B. A powder feed hose 30C is attached to the head body 22 by a fixing member (not shown) (refer to FIG. 3) and the powder feed hose 30C is connected with the powder feed path 29C. The respective other end portions of the powder feed hoses 30A, 30B, and 30C are connected to the metallic powder feed apparatus 41 (refer to FIG. 3). As shown in FIG. 3, the welding head scanning apparatus 23 includes a seating member 11, a support body 13, a rotator 16, a horizontal direction moving apparatus 18, a hoisting table 36, and a swing drive apparatus 37. A support body 13 is rotatably attached to the seating member 11. The support body 13 includes a lower support plate 12, an upper support plate 14, a pedestal 15, and a support member 33. The support member 33 is attached to the top of the lower support plate 12 rotatably attached to the seating member 11 and the upper support plate 14 is attached to an upper end of the support member 33. The pedestal 15 is attached to a top face of the upper support plate 14. A first motor (not shown) is fixed to an undersurface of the seating member 11 and a rotary shaft of the first motor is connected to the lower support plate 12 from the underneath. The first motor is a rotary apparatus of the support body 13. The rotator 16 includes a rotation plate 34 and the rotary shaft 35. The rotary shaft 35, on a surface of which a trapezoidal screw of a male screw is formed, passes through the upper support plate 14 and the pedestal 15 and an upper end portion of the rotary shaft 35 is rotatably attached to the pedestal 15. A lower end portion of the rotary shaft 35 is rotatably attached to the lower support plate 12. The rotation plate 34 is disposed above the pedestal 15 and is attached to the upper end portion of the rotary shaft 35. A second motor (not shown) configuring a rotation drive apparatus of the rotator 16 is installed on the top face of the pedestal 15. A rotary shaft of the second motor is connected to a worm (not shown) and the worm meshes with the rotation plate 34 which is a worm wheel. The hoisting table 36 forms a through-hole (not shown) through which the rotary shaft 35 passes and the trapezoidal screw of a female screw meshing with the trapezoidal screw of the rotary shaft 35 is formed on an inner surface of the through-hole (not shown). The rotary shaft 35 passes through the through-hole of the hoisting table 36 and the trapezoidal screw of the rotary shaft 35 meshes with the trapezoidal screw of the through-hole. A end portion of a rotation prevention member 40 installed on the hoisting table 36 is inserted into the groove (not shown) formed on the surface of the support member 33 opposite to the rotary shaft 35 and extending in an axial direction of the rotary shaft 35 so that the hoisting table 36 does not rotate in correspondence with the rotation of the rotary shaft 35. The groove is formed between the lower end of the support member 33 and the upper end thereof. By use of such a structure, the hoisting table 36 moves in the axial direction of the rotary shaft 35. The hoisting table 36 moves up and down along the rotary shaft 35 by driving of the second motor. The horizontal direction drive apparatus 18 is movably attached to an arm 17 attached to the hoisting table 36 and extending horizontally. A rod-shaped support member 19 is attached to the horizontal direction drive apparatus 18 and extends toward the underneath. A head holding member 20 is attached to a lower end portion of the support member 19. A rotary shaft 39 that is attached to the head body 22 of the powder laser welding head 21 is rotatably attached to the head holding member 20. The rotary shaft 39 extends horizontally. The swing drive apparatus 37 is installed on the head holding member 20. The swing drive apparatus 37 includes a third motor 38 and a rotary power transfer mechanism (not shown) including a reduction mechanism for transferring the rotary power of the third motor 38 to the rotary shaft 39. The third motor 38 is attached to the head holding member 20. The prevention maintenance method of the reactor internal of the nuclear power plant of the present embodiment will be explained below. The prevention maintenance method of the reactor internal of the nuclear power plant of the present embodiment is executed after the operation of the boiling water nuclear power plant is shut down. The prevention maintenance method will be explained based on the procedure (including each process of the steps S1 to S7) shown in FIG. 1 by referring to FIGS. 2 and 3 of Japanese Patent No. 4178027. In the boiling water nuclear power plant, as shown in FIG. 3, a plurality of control rod drive mechanism housings 3 and a plurality of in-core monitor housings 4 pass through the bottom (bottom head) of a reactor pressure vessel 1 and are attached to the bottom. Each control rod drive mechanism housing 3 is separately inserted into a plurality of stub tubes 2 attached to the inner surface of the bottom of the reactor pressure vessel 1 by welding, passes through the stub tubes 2 and the bottom of the reactor pressure vessel 1, and is attached to the stub tubes 2 by welding. Further, each in-core monitor housing 4 also passes through the bottom of the reactor pressure vessel 1 and is attached to the bottom by welding. In the prevention maintenance method of the present embodiment, to reduce the stress corrosion cracking of the respective welding portions 53 of each stub tube 2 and the bottom of the reactor pressure vessel 1, the excellent corrosion resistant build-up welding is executed on the surfaces of the welded portions. The internal equipment is detached and is transferred from the reactor pressure vessel (step S1). After the operation of the boiling water nuclear power plant is shut down, an upper cover of a reactor primary containment vessel surrounding the reactor pressure vessel 1 is detached and furthermore, an upper cover of the reactor pressure vessel 1 is removed. The respective detached upper covers of the reactor primary containment vessel and the reactor pressure vessel 1 are hanged by the ceiling crane of the reactor building surrounding the reactor primary containment vessel, are transferred to the operation floor positioned above the reactor primary containment vessel in the reactor building, and are kept on the operation floor. A reactor well formed above the reactor primary containment vessel in the reactor building, and the reactor pressure vessel 1 are internally filled with cooling water. Thereafter, the steam dryer and the steam separator installed in the reactor pressure vessel 1 are removed from the reactor pressure vessel 1 and are transferred outside the reactor pressure vessel 1 by the ceiling crane, and are kept in a dryer separator pool in the reactor building. The fuel assembly loaded in the core in the reactor pressure vessel 1 is also taken out by a fuel exchange apparatus moving on the operation floor and is transferred to and is kept in a fuel storage pool in the reactor building. The control rods are pulled up by the fuel exchange apparatus outside the reactor pressure vessel 1 and are transferred to and are kept in the fuel storage pool. A plurality of fuel supports placed on a core support plate installed in the reactor pressure vessel 1 and supporting the lower end portion of the fuel assembly are taken out from the reactor pressure vessel 1. Furthermore, a plurality of control rod guide tubes arranged below the core support plate in the reactor pressure vessel is taken out upward the core support plate through the opening formed in the core support plate to insert the fuel support and is transferred outside the reactor pressure vessel 1. The fuel supports and control rod guide tubes, for example, are hanged by the ceiling crane and are transferred upward. The aerial environment setting apparatus is installed (step S2). After all the fuel assemblies loaded in the core are transferred to the fuel storage pool, the aerial environment setting apparatus (not shown) is hanged by the ceiling crane and is attached on the flange attached to an upper end portion of the reactor pressure vessel 1 and attached to the flange in the state that the reactor well is filled with cooling water. A radiation shielding cover is used as an aerial environment setting apparatus. The radiation shielding cover is removably attached to the flange attached to the upper end portion of the reactor pressure vessel 1 and covers the reactor pressure vessel 1 as described in shown in FIG. 3 of Japanese Patent No. 4178027. The radiation shielding cover is not rotated. The radiation shielding cover is shown as a radiation shielding member 21c in Japanese Patent No. 4178027. In the present embodiment, the radiation shielding cover is removably attached to the flange in the cooling water though in Japanese Patent No. 4178027, radiation shielding member 21c is attached to a flange 1b of a reactor pressure vessel (RPV) 1 in a state that water level is lowered below a position of the RPV flange 1b. The radiation shielding cover shields a radiation discharged upward from the reactor pressure vessel 1. The radiation shielding cover used in the present embodiment, for example, is a radiation shielding cover with a plurality of openings formed to insert the guide pipes shown in FIG. 4A of Japanese Patent No. 4178027. Each opening formed in the radiation shielding cover positions right above each control rod drive mechanism housing 3 attached to the bottom of the reactor pressure vessel 1. Each opening formed in the radiation shielding cover is closed by a closing plug made of the radiation shielding material. When the radiation shielding cover is attached on the flange of the upper end portion of the reactor pressure vessel 1, each opening formed in the radiation shielding cover is positioned right above each stub tube 2. As a radiation shielding cover used in the present embodiment, the radiation shielding cover described in either of FIG. 4B and FIG. 4C of Japanese Patent No. 4178027 may be used. The insertion of the guide pipe into the reactor pressure vessel is performed as described below. In the state that the reactor pressure vessel is filled with cooling water, the closing plug existing at position into which the guide pipe is inserted, concretely, right above the stub tubes 2 subjected to build-up welding of the repair and the prevention maintenance, the closing plug closing each opening formed in the radiation shielding cover, is detached and taken out from the reactor pressure vessel and the guide pipe is inserted into the opening. The guide pipe is divided into a plurality of portions in the axial direction and the guide pipe inserted into the aforementioned opening descends toward the bottom of the reactor pressure vessel 1 by adding (refer to Japanese Patent No. 4178027). The descent of the guide pipe is stopped when the lower end of the guide pipe reaches a predetermined position below the core support plate installed in the reactor pressure vessel 1. When a lower end of the guide pipe is arrived at the predetermined position in the axial direction of the reactor pressure vessel 1, the upper end of the guide pipe is removably attached on the top face of the radiation shielding cover. To effectively perform the repair and the prevention maintenance operation, the guide pipe may be inserted from each of the plurality of openings formed in the radiation shielding cover. By doing this, the build-up welding of the welding portion of each of the stub tubes 2 which will be described later can be performed in a plurality of places in parallel. The water in the reactor pressure vessel is discharged and an aerial environment is formed in the reactor pressure vessel (step S3). The open/close valve installed in a drain pipe (not shown) connected to the bottom head of the reactor pressure vessel is opened and the cooling water in the reactor well and the reactor pressure vessel is discharged outside the reactor pressure vessel through the drain pipe. According to the discharge of cooling water, a water surface of the cooling water in the reactor well lowers and the water surface soon lowers below the first radiation shielding cover in the reactor pressure vessel. When the cooling water in the reactor pressure vessel is all discharged, the aerial environment is formed in the reactor pressure vessel. The repair and the prevention maintenance operation are executed (step S4). The repair and the prevention maintenance operation of step 4 include each process of steps S4A to S4E which are shown in FIG. 2. The repair and the prevention maintenance operation will be explained in detail by referring to FIG. 2. The oxide film in the zone where the repair and the prevention maintenance operation are executed is removed (step S4A). When the boiling water nuclear power plant is in operation, an oxide film including a radioactive nuclide is formed on each surface of the respective welding portions 53 between each stub tube 2 and the bottom of the reactor pressure vessel 1. Therefore, the oxide film is removed before the build-up welding is performed on each surface of the welding portions 53. The oxide film is removed, thus the radioactive nuclide is also removed, and in the build-up welding performed for prevention maintenance, the radioactive nuclide can be avoided from imprisoning into the build-up welding. The decontamination operation of removing the oxide film is performed by the grinding apparatus described in Japanese Patent Laid-open No. 2011-52966 or the chemical decontamination described in Japanese Patent No. 4178027. The decontamination by the grinding apparatus is preferably applied when performing the repair and the prevention maintenance in a specific welding portion and the decontamination by the chemical decontamination is preferably applied when performing the repair and the prevention maintenance within a wide range. In the present embodiment, the respective welding portions 53 between all the stub tubes 2 attached to the bottom of the reactor pressure vessel 1 and the bottom of the reactor pressure vessel 1 are an object of prevention maintenance and in order to decontaminate the entire inner surface of the bottom of the reactor pressure vessel 1, the chemical decontamination is applied. A chemical decontamination liquid is fed to the zone below the core support plate in the reactor pressure vessel 1 from the drain pipe (not shown) connected to the bottom of the reactor pressure vessel 1. The feed of the chemical decontamination liquid is performed until the respective welding portions 53 are all immersed in the chemical decontamination liquid. As chemical decontamination, oxide decontamination and reduction decontamination are performed. Therefore, the oxide decontamination liquid (for example, a potassium permanganate aqueous solution) and the reduction decontamination liquid (for example, an oxalic acid aqueous solution) which are a chemical decontamination liquid are fed in sequence. Firstly, the oxide decontamination liquid is fed from the drain pipe to a lower plenum 52 in the reactor pressure vessel 1 and the oxide decontamination for each welded portion aforementioned is performed. In the boiling water nuclear power plant, the lower plenum 52 is a region formed below the core, to be more specific, the core support plate in the reactor pressure vessel 1. After completion of the oxide decontamination, the oxide decontamination liquid in the reactor pressure vessel 1 is discharged from the drain pipe and is processed. Thereafter, the reduction decontamination liquid is fed from the drain pipe to the lower plenum 52 and the reduction decontamination for each oxide-decontaminated welded portion is executed. After completion of the reduction decontamination, the reduction decontamination liquid is discharged from the lower plenum 52 in the reactor pressure vessel 1 into the drain pipe and is processed. The inspection for a surface of the repair and prevention maintenance object zone before welding is executed (step S4B). For example, a penetrant test apparatus is hanged by the ceiling crane and descends to the lower plenum 52 in the reactor pressure vessel 1 through the guide pipe held by the radiation shielding cover. Using the penetrant test apparatus, the inspection for the surface of the welding portion 53 between the stub tube 2 and the bottom of the reactor pressure vessel 1 is executed. This stub tube 2 positions right under the guide pipe. By the penetrant inspection using the penetrant inspection apparatus, when a crack is found in the welded portion, in the corresponding welded portion, the repair operation for the crack is performed and thereafter, for the surface of the corresponding welded portion, the build-up welding which is the prevention maintenance operation needs to be performed. When no crack is found in the welded portion, the build-up welding is performed. After end of the surface inspection, the penetrant test apparatus is pulled up through the guide pipe. When a crack is found in the welded portion, the working apparatus for removing the cracking portion of the welded portion descends to the position of the welded portion via the guide pipe. Using the working apparatus, the cracking portion of the welded portion is cut off and the crack is removed. The cutting scrap generated by cutting is sucked by the sucking device (not shown) and is discharged out from the reactor pressure vessel 1. The welding operation is executed (Step S4C). In the respective welding of repair and prevention maintenance, the powder laser welding apparatus 10 shown in FIG. 3 is used. The powder laser welding apparatus 10 is hanged down by the ceiling crane and descends in the guide pipe up to the upper end position of the control rod drive mechanism housing 3 attached to the stub tube 2 positioned in the corresponding welding portion 53. The seating member 11 of the powder laser welding apparatus 10 is seated at the upper end of the control rod drive mechanism housing 3, and the projection (not shown) installed on the under surface of the seating member 11 and the aforementioned first motor are inserted into the control rod drive mechanism housing 3. In this way, the powder laser welding apparatus 10 is positioned and the powder laser welding apparatus 10 is prevented from tumble by the projection inserted into the control rod drive mechanism housing 3. Here, the build-up welding (prevention maintenance welding) when no crack is found in the welding portion 53 between the stub tube 2 positioned right under the guide pipe and the bottom of the reactor pressure vessel 1 will be explained. When the powder laser welding apparatus 10 is seated at the upper end of the control rod drive mechanism housing 3, the powder laser welding head 21 and the support member 19 are arranged between the control rod drive mechanism housing 3 where the powder laser welding apparatus 10 is seated and another control rod drive mechanism housing 3 adjacent to the former control rod drive mechanism housing 3. The third motor 38 of the swing drive apparatus 37 is driven to rotate the rotary shaft 39 and the powder laser welding head 21 is rotated in the axial direction of the control rod drive mechanism housing 3 until the central axis of the powder laser welding head 21 is inclined, for example, at 50° relative to the surface of the welding portion 53 subjected to the build-up welding. When the central axis of the powder laser welding head 21 is inclined at 50° relative to the surface of the welding portion 53, the driving of the third motor 38 is stopped. The horizontal direction drive apparatus 18 is moved along the arm 17 and the distance in the horizontal direction between the welding portion 53 and the laser outlet of the powder laser welding head 21 is adjusted. When the distance becomes a first predetermined distance, the movement of the horizontal direction moving apparatus 18 is stopped. Next, the distance in the axial direction of the control rod drive mechanism housing 3 between the welding portion 53 and the laser outlet thereof is adjusted to a second predetermined distance. The adjustment of the distance in the axial direction of the control rod drive mechanism housing 3 is performed by rotating the rotary shaft 35 by driving the second motor and moving the hoisting table 36 meshing with the trapezoidal screw of the rotary shaft 35 in the axial direction of the control rod drive mechanism housing 3. When the distance in the axial direction of the control rod drive mechanism housing 3 between the welding portion 53 between the stub tube 2 and the bottom of the reactor pressure vessel 1 and the laser outlet of the powder laser welding head 21 becomes the second predetermined distance, the second motor is stopped. The laser outlet of the powder laser welding head 21 is opposite to the surface of the welding portion 53. The optical fiber 26 and the powder feed hoses 30A, 30B, and 30C which are connected to the head body 22 of the powder laser welding head 21 pass through the guide pipe and reach above the reactor pressure vessel 1. The laser oscillator connected to the optical fiber 26 and the metallic powder feed apparatus 41 connected to the powder feed hoses 30A, 30B, and 30C are installed on the operation floor in the reactor building. The laser oscillator is operated and for example, a laser 28A of power of 1 kW generated by the laser oscillator satisfying P>10.5 πD2 enters the optical fiber 26. The laser 28A passes through the optical fiber 26 and is transmitted to the end of the optical fiber 26 on the side of a lens housing 24 (refer to FIG. 4). In the lens housing 24, the laser 28A emitted from the end of the optical fiber 26 spreads and enters the collimate lens 25. The laser 28A has a power density of 44 W/mm2 and becomes a laser 28B of a parallel beam by the collimate lens 25 (refer to FIG. 4) and enters the laser path 27 formed in the head body 22. The laser 28B with a spot diameter D of 5.4 mm of the parallel beam passing through the laser path 27 is emitted from the laser outlet formed in the head body 22 and is irradiated on the surface, for which the build-up welding is performed, of the welding portion 53 between the stub tube 2 and the bottom of the reactor pressure vessel 1. By the irradiation of the laser 28B, the surface of the welding portion 53 is melted. On the other hand, the metallic powder (for example, powder of the excellent corrosion resistant Inconel 52 alloy capable of suppressing the stress corrosion cracking) which is a filler metal fed from the metallic powder feed apparatus 41 is introduced to the powder feed paths 29A, 29B, and 29C which are formed in the head body 22 through the powder feed hoses 30A, 30B, and 30C, respectively. The total amount of the metallic powder fed to the powder feed paths 29A, 29B, and 29C, that is, the metallic powder feed quantity M is, for example, 0.17 g/W·s satisfying M<0.26×P×t. The metallic powder is jetted from the respective powder injection outlets of the powder feed paths 29A, 29B, and 29C toward the fusion zones of the welding portion 53 mentioned above. Here, the adjustment of the aforementioned laser power 1 kW for satisfying P>10.5 πD2 and the aforementioned metallic powder feed amount M 0.17 g/W·s for satisfying M<0.26×P×t will be explained. The diameter D of the laser 28B varies with the distance from the exit of the optical fibers 26 to the collimate lens 25, so that the relation between the diameter D and the distance is obtained beforehand and when producing the powder laser welding head 21, the collimate lens 25 is disposed at the position where the diameter D of the laser 28B becomes the target diameter D0, this is, 5.4 mm. In the powder laser welding apparatus 10, the powder laser welding head 21 produced in this way is used. The laser power P is adjusted by the laser oscillator. Concretely, the laser power P is adjusted, for example, to 1 kW by the laser oscillator so as to obtain the target power density 42 W/mm2 or higher, for example, 44 W/mm2 on the basis of the diameter 5.4 mm of the laser 28B. The metallic powder feed amount M is adjusted, for example, to 0.17 g/W·s by the metallic powder feed apparatus 41. The metallic powder discharged from the powder injection outlet and reaching the fusion zone is heated and melted by the laser 28B emitted from the laser outlet of the powder laser welding head 21. The powder laser welding head 21 is permitted to rotate around the welding portion 53 to be subjected to the build-up welding while emitting the laser from the laser outlet of the laser path 27 and discharging the metallic powder from the respective powder injection outlets of the powder feed paths 29A, 29B, and 29C. The rotation of the powder laser welding head 21 is performed by driving the first motor fixed to the under surface of the seating member 11. The lower support plate 12, that is, the support body 13 rotates by driving the first motor and the rotator 16 rotates. By these rotations, the hoisting table 36 meshing with the rotary shaft 35 rotates and the arm 17 attached to the hoisting table 36 rotates around the central axis of the control rod drive mechanism housing 3 in the horizontal surface. Therefore, the powder laser welding head 21 rotates around the concerned stub tube 2. The inner surface of the bottom of the reactor pressure vessel 1 is a curved surface, so that the position of the welding portion 53 in the axial direction of the reactor pressure vessel 1 is different depending on a peripheral direction of the welding portion 53. Namely, the position of the welding portion 53 in the axial direction of the reactor pressure vessel 1 is low on the central axis side of the reactor pressure vessel 1 and high on the side wall side of the reactor pressure vessel 1. In consideration of such a position difference of the welding portion 53 in the axial direction of the reactor pressure vessel 1, in order to keep the distance of in the axial direction the control rod drive mechanism housing 3 between the welding portion 53 and the laser outlet of the laser path 27 at the second predetermined distance, the second motor is driven to move up and down the hoisting table 36 while rotating the powder laser welding head 21 around the concerned stub tube 2. According to the above, over the entire periphery in the peripheral direction of the welding portion 53 between the stub tube 2 and the bottom of the reactor pressure vessel 1, the excellent corrosion resistant build-up welding portion, that is, the excellent corrosion resistant welding overlay for suppressing the stress corrosion cracking can be formed on the surface of the welding portion 53. The monitoring camera (not shown) is attached to the under surface of the head holding member 20. After completion of the build-up welding, the arm 17 is rotated by driving the first motor in the state that the emission of the laser 28A to the optical fiber 26 and the feed of metallic powder to the powder feed paths 29A, 29B, and 29C are stopped. Therefore, the powder laser welding head 21 and the monitoring camera rotate around the stub tube 2 subjected to the build-up welding. The monitoring camera rotates while taking photographs of the surface of the buildup welding portion. The image information of the surface of the buildup welding portion photographed by the monitoring camera is transmitted to a display apparatus (not shown) connected to the monitoring camera and disposed on the operation floor through the cable for transmitting the image information. The transmitted image information is displayed on the display apparatus. An operator on the operation floor looks at the image displayed on the display apparatus and monitors the state of the surface of the build-up welding portion. When adhesion of non-welded metallic powder which is a filler metal to the surface of the build-up welding portion is observed based on the displayed image, the laser 28B converted to the parallel beam by the collimate lens 25 is irradiated to the surface of the build-up welding portion formed on the surface of the welding portion 53 in a state that the laser 28A generated by the laser oscillator is permitted to enter the optical fibers 26 and the feed of metallic powder to the powder feed paths 29A, 29B, and 29C is stopped (in the non-filler state). The non-welded metallic powder adhered on the surface of the build-up welding portion is melted by the irradiation of the laser 28B. The support body 13 and the rotator 16 are rotated by driving the first motor and the powder laser welding head 21 is rotated around the stub tube 2 subjected to the build-up welding on the welding portion 53 while by emitting the laser 28B in the non-filler state. Therefore, the non-welded metallic powder adhered on the surface of the build-up welding portion can be melted over the entire periphery of the build-up welding portion. When the adhesion of the non-welded metallic powder on the surface of the build-up welding portion is not observed based on the image displayed on the display apparatus, the emission of the laser 28 on the surface of the build-up welding portion in the aforementioned non-filler state is not performed. After completion of the aforementioned build-up welding, the powder laser welding apparatus 10 is pulled up by using the ceiling crane through the guide pipe, is taken out from the reactor pressure vessel 1, and is come up to the operation floor. When a crack is found in the welding portion 53 at step S4B, as mentioned above, the cracking portion of the welding portion 53 is removed by cutting by the working apparatus. Thereafter, the repair welding is performed for the crack-removed portion of the welding portion 53 at step S4C. In the repair welding, the powder laser welding apparatus 10 transferred via the guide pipe is used. In the repair welding, the metallic powder is jetted from the respective powder injection outlet of the powder feed paths 29A, 29B, and 29C while irradiating the laser 28B emitted from the laser outlet of the powder laser welding head 21 to the crack-removed portion of the welding portion 53, and the repair welding for the crack-removed portion is performed. After completion of the repair welding, the build-up welding for the surface of the welding portion 53 is executed as aforementioned. When the crack generated in the welding portion 53 is small, using the powder laser welding head 21 of the powder laser welding apparatus 10, the crack is repaired by the non-filler laser welding. In step S4B, the inspection for the surface of the welding portion 53 may be executed by an ultrasonic test apparatus instead of the penetrant test apparatus. It is assumed that a crack 42 of a depth of t1 shown in (A) shown in FIG. 6 is found in the welding portion 53 by the ultrasonic test in which the ultrasonic test apparatus is used. As mentioned above, the laser outlet of the laser path 27 formed in the head body 22 is permitted to face the crack 42 by driving the first motor, second motor, and third motor and the distance in the horizontal direction between the welding portion 53 and the laser outlet of the powder laser welding head 21 is adjusted to the first predetermined distance. Furthermore, the distance in the axial direction of the control rod drive mechanism housing 3 between the welding portion 53 and the laser outlet of the powder laser welding head 21 is adjusted to the second predetermined distance. The laser oscillator is operated and the laser 28A with power of 1 kW enters the optical fiber 26. The laser 28B converted to a parallel beam by the collimate lens 25 in the head body 22 is irradiated toward the portion of the welding portion 53 where the crack 42 exists from the laser discharge opening of the laser path 27. The power density of the irradiated laser 28B is, for example, 44 W/mm2. At this time, the feed of metallic power from the metallic powder feed apparatus 41 to the powder feed hoses 30A, 30B, and 30C is stopped. The portion of the welding portion 53 where the crack 42 exists is melted by the irradiation of the laser 28B. The position of the laser outlet of the laser path 27 is changed by driving each of the first motor, second motor, and third motor and the welding portion around the crack 42 is melted. A melting portion 43 with no crack 42 formed by the melting is formed on the welding portion 53. When the depth of the crack 42 is t1, and the power density of the laser 28B is 42 W/mm2 or higher, and a melting depth t2 of the welding portion 53 for performing the melting process of the crack 42 satisfies t2>t1, the repair of the crack 42 generated in the welding portion 53 is enabled by the laser 28B (refer to (B) shown in FIG. 6). Therefore, the non-filler laser 28B can be applied to the repair operation of the crack. When the repair by the non-filler laser welding for removing the crack 42 to the welding portion 53 is finished, the laser oscillator is stopped and the irradiation of the laser 28B is stopped. Soon, the melting portion 43 solidifies in the state that the crack 42 is repaired. A surface of the build-up welding portion is ground (step S4D). The grinder hanged by the ceiling crane descends through the guide pipe and reaches the neighborhood of the welding portion 53 between the stub tube 2 and the bottom of the reactor pressure vessel 1. Using the grinder, the surface of the build-up welding portion formed on the welding portion 53 is ground. The grinding is executed over the entire periphery in the peripheral direction of the build-up welding portion. After completion of grinding of the surface of the build-up welding portion, the grinder is pulled up in the guide pipe and transferred to the operation floor. When the repair by the aforementioned non-filler laser welding is performed, after completion of this repair, the surface of the welding portion 53 including the solidified melting portion 43 between the stub tube 2 and the bottom of the reactor pressure vessel 1 is also ground by the grinder. The surface inspection of the build-up welding portion after build-up welding is executed (step S4E). Similarly to the step S4B, the penetrant inspection apparatus is hanged by the ceiling crane and descends to the lower plenum 52 of the reactor pressure vessel 1 through the guide pipe held by the radiation shielding cover. Using the penetrant inspection apparatus, the surface inspection of the build-up welding portion whose surface has been ground is executed. After completion of the surface inspection of the build-up welding portion, the penetrant inspection apparatus is hanged by the ceiling crane and is transferred to the operation floor through the guide pipe. According to the above, the build-up welding for the surface of one welding portion 53 between the stub tube 2 and the bottom of the reactor pressure vessel 1 or the build-up welding executed in parallel for the surfaces of a plurality of welding portions 53 between the stub tubes 2 and the bottom of the reactor pressure vessel 1 finishes. Thereafter, each operation at the steps S4A to S4E is executed for the welding portion 53 between another stub tube 2 existing on the bottom of the reactor pressure vessel 1 and the bottom thereof. As mentioned above, each operation at the steps S4A to S4E is repeated, thus the repair and prevention maintenance operation for each welding portion 53 between all the stub tubes 2 existing on the bottom of the reactor pressure vessel 1 and the bottoms thereof, that is, the repair and prevention maintenance operation in step S4 finish. The reactor pressure vessel is filled with water (step S5). The penetrant inspection apparatus is transferred to the operation floor and after the operation at step S4 finishes, cooling water is fed to the reactor pressure vessel 1. After cooling water is fed up to a predetermined water level, the feed of cooling water into the reactor pressure vessel 1 is stopped. The aerial environment setting apparatus is removed (step S6). The guide pipe inserted into the opening of the radiation shielding cover installed on the flange at the upper end of the reactor pressure vessel 1 is hanged by the ceiling crane, is pulled up, and is removed from the radiation shielding cover. After the guide pipe is removed, the opening of the radiation shielding cover is closed by the closing plug. After completion of removal of the guide pipe, the radiation shielding cover on the flange of the reactor pressure vessel 1 is hanged up by the ceiling crane and is collected on the operation floor. The internal equipment is installed (step S7). The internal equipment removed at step S1 is installed in the reactor pressure vessel 1. The control rod guide pipes and fuel supports are hanged in order by the ceiling crane and are transferred into the reactor pressure vessel 1. These are installed at predetermined positions in the reactor pressure vessel 1. After all the fuel supports are installed, the control rods are transferred into the reactor pressure vessel by the fuel exchange apparatus and are disposed in each control rod guide pipe through the through-hole formed in the fuel support. The fuel assemblies are loaded in the core in the reactor pressure vessel 1 from the fuel storage pool by the fuel exchange apparatus. The steam separator and the steam dryer are hanged in order by the ceiling crane, are transferred into the reactor pressure vessel 1, and are installed in a predetermined position in the reactor pressure vessel 1. Thereafter, the upper cover of the reactor pressure vessel 1 is attached to the flange of the reactor pressure vessel 1 and the upper cover of the primary containment vessel is installed at the upper end of the primary containment vessel. According to the above, all the processes of the prevention maintenance method of the reactor internal of the nuclear power plant according to the present embodiment finish. The powder laser welding apparatus 10 including the powder laser welding head 21 can be applied to the repair and the prevention maintenance operation for the welding portion between the stub tube 2 and the control rod drive mechanism 3 and each aforementioned process of the steps S1 to S7 can be executed. Particularly, each aforementioned process of the steps S4A to S4E can be executed and the repair welding for the welding portion between the stub tube 2 and the control rod drive mechanism 3, and the build-up welding to the surface of the concerned welding portion can be executed. According to the present embodiment, the powder laser welding head 21 of the powder laser welding apparatus 10 includes only the collimate lens 25 as a lens but includes no condensing lens, so that the length of the powder laser welding head 21 is approximately 70 mm, which is about 1/10 of the length of the conventional powder laser welding head (760 mm). In this way, the powder laser welding head 21 can be shortened in length and is made compact. In the present embodiment, the powder laser welding head 21 shortened in length is used, so that when performing the repair welding and the build-up welding of prevention maintenance for the welding portion 53 between the stub tube 2 and the bottom of the reactor pressure vessel 1 or another welding portion between the stub tubes 2 and the control rod drive mechanism housings 3 in the lower plenum 52 of the reactor pressure vessel 1 where many stub tubes 2, control rod drive mechanism housings 3, and in-core monitor housings 4 stand together to form a narrow portion, the interference with another stub tube 2, control rod drive mechanism housing 3, and in-core monitor housing 4 adjoining the stub tube 2 of a welding object and forming a narrow portion between the stub tubes 2 of a welding object can be avoided and the powder laser welding head 21 can be rotated around the stub tube 2 of the welding object. Thus, the powder laser welding can be performed easily for the welding portion of the stub tube 2 facing the narrow portion 53 and the time required for the build-up welding operation by the powder laser welding head 21 can be shortened. In the present embodiment, the welding is performed by the laser irradiation, so that the high-speed welding is enabled, thus the welding operation time can be shortened. Namely, the laser welding which is a prevention maintenance object using powder for the welding portion 53 of the stub tube 2 of a welding object which is a prevention maintenance object can be performed easily and the time required for the prevention maintenance operation can be shortened. Further, in the present embodiment, since the powder laser welding head 21 of the powder laser welding apparatus 10 includes only the collimate lens 25 as a lens, the laser 28B generated by the collimate lens 25 is irradiated to the welding object, so that there is no need to fit the welding place of the welding object to the focal position of the condensing lens like the conventional laser welding head using the condensing lens and even when the distance between the powder laser welding head 21 and the welding place of the welding object varies with the movement of the powder laser welding head 21, good powder welding (powder laser welding obtaining a pass rate of 100%) can be performed for the welding place of the welding object. According to the present embodiment, metallic powder (for example, powder of an Inconel 52 alloy) more excellent in the corrosion resistance than the reactor internal (for example, the stub tube 2 and the control rod drive mechanism housing) is built up on the surface of the welding portion (for example, the welding portion 53), so that the stress corrosion cracking in the welding portion of the reactor internal can be suppressed. In the present embodiment, the power P of the laser 28B to be irradiated to the welding portion is 1 kW satisfying P>10.5 πD2 and furthermore, the metallic powder feed amount M is 0.17 g/W·s satisfying M<2.6×P×t, so that good build-up welding portion using metallic powder with a pass rate of 100% can be obtained. In the present embodiment, when non-welded metallic powder is adhered on the surface of the build-up welding portion generated by the feed of metallic powder and the irradiation of the laser 28B, the laser 28B is irradiated on the surface of the build-up welding portion and the adhered non-welded metallic powder is melted in the state (non-filler state) that no metallic powder is fed, so that the surface of the build-up welding portion can be improved from the rough surface with non-welded metallic powder adhered to a smoother surface. As a result, the surface of the build-up welding portion is made smooth by the irradiation of the laser 28B in the non-filler state, so that there is no need to perform the grinding operation to the rough surface of the build-up welding portion with non-welded metallic powder adhered thereto for the purpose of inspection after the build-up welding. Since the grinding operation requiring a long time becomes unnecessary, the inspection of the build-up welding portion can be started that much sooner. Therefore, the time requiring the prevention maintenance operation by the build-up welding can be shortened. The lower plenum 52 in the reactor pressure vessel 1, in which the welding portion 53 and the like, which an object of the repair welding and the prevention maintenance build-up welding in the reactor pressure vessel 1, exists, is set in the aerial environment, so that the powder laser welding to the concerned welding portion can be performed easily. When performing the powder laser welding in water, the metallic powder which is a filler metal jetted from the powder feed paths 29A and 29B and the like cannot be fed to the welding place of the welding portion 53 and the like due to the resistance of water and the build-up welding to the welding portion 53 and the like cannot be performed satisfactorily. When performing the powder laser welding in the aerial environment, such a problem does not arise. The prevention maintenance method of the reactor internal of the nuclear power plant according to embodiment 2 which is another suitable embodiment of the present invention will be explained below. The prevention maintenance method of the reactor internal of the present embodiment is applied to reactor internal existing in a reactor pressure vessel of a pressurized water nuclear power plant. In the present embodiment, the reactor internal which is a prevention maintenance object is a bottom mounted instrumentation nozzle which is a tubular structure, and more specifically, a tubular member and the prevention maintenance is executed for the welding portion between the bottom mounted instrumentation nozzle (corresponds to the in-core monitor housing 4 in the boiling water nuclear power plant) and the bottom of the reactor pressure vessel 1. In the prevention maintenance method of the reactor internal of the nuclear power plant of the present embodiment, a powder laser welding apparatus 10A shown in FIG. 14 is used. The powder laser welding apparatus 10A has a constitution where a seating member 31 is attached to the powder laser welding apparatus 10 used in embodiment 1. The other structure of the powder laser welding apparatus 10A is the same as that of the powder laser welding apparatus 10. The outside diameter and inside diameter of a bottom mounted instrumentation nozzle 44 are smaller than the outside diameter and inside diameter of the control rod drive mechanism housing 3 on which the powder laser welding apparatus 10 is seated. For this reason, it is difficult to make the powder laser welding apparatus 10 seated at the upper end of the bottom mounted instrumentation nozzle 44 so that it will be held by the bottom mounted instrumentation nozzle 44. The powder laser welding apparatus 10A includes a seating member 31 so that the powder laser welding apparatus 10 is seated easily at the upper end of the bottom mounted instrumentation nozzle 44 and is held easily by the bottom mounted instrumentation nozzle 44. The seating member 31 is smaller in the outside diameter than the seating member 11 and includes the projection inserted into the bottom mounted instrumentation nozzle 44 for preventing the powder laser welding apparatus 10A from tumble on the under surface of the seating member 11. The seating member 31 is attached to the under surface of the seating member 11. The first motor which is a rotation apparatus of the support body 13 is attached to the under surface of the seating member 11 and is disposed inside the seating member 31. In the prevention and maintenance executed for the welding portion 53A between the bottom mounted instrumentation nozzle 44 and the bottom (bottom head) of the reactor pressure vessel 1 in the pressurized water nuclear power plant, the operations described in the paragraphs 0031 to 0051 of Japanese Patent Laid-open No. 2011-52966 (the paragraphs 0053 to 0080 of US2011/0051878A1) are performed. In the present embodiment, the common access apparatus is hanged by the ceiling crane, descends into the reactor pressure vessel 1 filled with water, and is set on the inner surface of the bottom of the reactor pressure vessel 1 (refer to FIGS. 2 and 3 of Japanese Patent Laid-open No. 2011-52966). The cover apparatus to which the guide pipe is attached for covering the common access apparatus is hanged by the ceiling crane, descends in the reactor pressure vessel 1, and is set on the inner surface of the bottom of the reactor pressure vessel 1 (refer to FIGS. 4 and 7 of Japanese Patent Laid-open No. 2011-52966). Water is removed from a zone in which the common access apparatus disposed and which exists below the cover apparatus in the reactor pressure vessel 1 and the zone is set in the aerial environment (refer to FIGS. 10 and 11 of Japanese Patent Laid-open No. 2011-52966). The water pressure above the cover apparatus existing in the reactor pressure vessel 1 is added to the cover apparatus by forming the aerial environment below the cover apparatus in the reactor pressure vessel 1, so that the cover apparatus is pressed to the inner surface of the bottom of the reactor pressure vessel 1 and the sealing property between the cover apparatus and the inner surface of the bottom of the reactor pressure vessel 1 is improved. The powder laser welding apparatus 10A, the penetrant inspection apparatus, and the grinder are fallen by hanging through the guide pipe, and are set to the metal fitting members attached to the arm of the common access apparatus. Thereafter, the operation of each process of steps S4A to S4E executed in embodiment 1 is executed in order. The chemical decontamination (step S4A) of the inner surface of the bottom of the reactor pressure vessel 1 is executed and using the penetrant inspection apparatus, the inspection of the surface of the welding portion 53A between a certain bottom mounted instrumentation nozzle 44 and the bottom of the reactor pressure vessel 1 is executed (step S4B). Next, the welding operation is executed (step S4C). The powder laser welding apparatus 10A is permitted to descend from the arm and the seating member 31 of the powder laser welding apparatus 10A is set at the upper end of a certain bottom mounted instrumentation nozzle 44 joined to the bottom of the reactor pressure vessel 1 by the welding portion 53A to be subjected to the build-up welding. When no crack is found in the welding portion 53A by the surface inspection at step S4B, the central axis of the powder laser welding head 21 is inclined, for example, at 50° relative to the surface of the welding portion 53A subjected to the build-up welding. Thereafter, similarly to embodiment 1, the laser 28B discharged from the laser outlet of the powder laser welding head 21 is irradiated on the surface of the welding portion 53A, and the metallic powder (for example, powder of the Inconel 52 alloy) which is a filler metal is fed to the surface of the welded portion 53A melted by the laser 28B from the metallic powder feed apparatus 41 through the powder feed paths 29A, 29B, and 29C. As a consequence, the build-up welding is performed to the surface of the welded portion 53A. Similarly to embodiment 1, the arm 17 is rotated by rotating the support body 13 and the rotator 16, and the powder laser welding head 21 is also rotated around the welding portion 53A of the bottom mounted instrumentation nozzle 44 subjected to the build-up welding. As a result, the build-up welding is performed over the entire periphery of the welding portion between the bottom mounted instrumentation nozzle 44 and the bottom of the reactor pressure vessel 1. After completion of the build-up welding, the grinding of the surface the build-up welding portion on the welding portion 53A at step S4D and the inspection of the surface of the build-up welding portion at step S4E are executed. Each operation at steps S4B to S4E is repeated and the build-up welding for each welding portion 53A between all the bottom mounted instrumentation nozzles 44 attached to the bottom of the reactor pressure vessel 1 and the reactor pressure vessel 1 is executed in order. After completion of these build-up welding operations, water is fed to the zone in which the common access apparatus disposed and which exists below the cover apparatus in the reactor pressure vessel 1, and the zone is filled with water. Thereafter, the cover apparatus and the common access apparatus are pulled up by the ceiling crane in order and are transferred outside the reactor pressure vessel 1. This completes the prevention maintenance method of the present embodiment. The present embodiment can obtain each effect generated in embodiment 1. The prevention maintenance method of the reactor internal of the nuclear power plant according to embodiment 3 which is still another preferred embodiment of the present invention will be explained below. The prevention maintenance method of the reactor internal of the present embodiment is applied to the reactor internal existing in the reactor pressure vessel of the boiling water nuclear power plant. In embodiment 1, the reactor internal which is a prevention maintenance object is the stub tube 2 which is a tubular structure or the control rod drive mechanism housing 3, though in the present embodiment, the prevention maintenance is executed for the welding portion of the in-core monitor housing 4 which is a tubular structure and the bottom of the reactor pressure vessel 1. The in-core monitor housing 4 is shown in FIG. 3. In the prevention maintenance method of the reactor internal of the nuclear power plant of the present embodiment, the aforementioned powder laser welding apparatus 10A used in embodiment 2 shown in FIG. 14 is used. The prevention maintenance method in the present embodiment will be explained. Similarly to embodiment 1, the operation of each process at steps S1 to S3 is executed. At step S4, similarly to embodiment 1, the operation of each process at steps S4A to S4E is executed in order. The welding operation at step S4C, concretely, the build-up welding on the surface of the welding portion between the in-core monitor housing 4 and the bottom of the reactor pressure vessel 1 will be explained below. When the powder laser welding apparatus 10A descending in the guide pipe and transferred is seated at an upper end of the in-core monitor housing 4 subjected to the build-up welding, the powder laser welding head 21 and the support member 19 are disposed between the in-core monitor housing 4 on which the powder laser welding apparatus 10 seated and another control rod drive mechanism housing 3 adjacent to in-core monitor housing 4. When no crack is found in the welding portion between the in-core monitor housing 4 and the bottom of the reactor pressure vessel 1 by the surface inspection at step S4B, the central axis of the powder laser welding head 21 is inclined, for example, at 50° relative to the surface of the welding portion subjected to the build-up welding. Thereafter, similarly to embodiment 1, the laser 28 discharged from the laser outlet of the powder laser welding head 21 is irradiated on the surface of the welding portion, and the metallic powder (for example, powder of the Inconel 52 alloy) which is a filler metal is fed to the surface of the welding portion melted by the laser 28 and the build-up welding is performed to the surface of the welding portion. The arm 17 is rotated by rotating the rotary shaft 35, and the powder laser welding head 21 is rotated around the welding portion subjected to the build-up welding. As a result, the build-up welding is performed over the entire periphery of the welding portion between the in-core monitor housing 4 and the bottom of the reactor pressure vessel 1. After completion of the build-up welding, the grinding of the surface of the build-up welding portion at step S4D and the inspection of the surface of the build-up welding portion after the build-up welding at step S4E are executed. Each operation at steps S4B to S4E is repeated and the build-up welding for each welding portion between all the in-core monitor housing 4 attached to the bottom of the reactor pressure vessel 1 and the reactor pressure vessel 1 is executed in order. After completion of these build-up welding operations, each operation at steps S5 to S7 is performed in order and the prevention maintenance method of the present embodiment finishes. The present embodiment can obtain each effect generated in embodiment 1. The cutting method of the reactor internal of the nuclear power plant according to embodiment 4 which is other preferred embodiment of the present invention will be explained by referring to FIGS. 15, 16, and 17. The cutting method of the reactor internal of the present embodiment is applied to the reactor internal existing in the reactor pressure vessel of the boiling water nuclear power plant. In the cutting method of the reactor internal of the present embodiment, a laser cutting apparatus 45 shown in FIG. 17 is used. The laser cutting apparatus 45 includes a laser cutting head (cutting head) 46, a cutting head scanning apparatus 49, and a gas feed apparatus 50. The laser cutting head 46 has a structure where in the powder laser welding head 21 of the powder laser welding apparatus 10, one gas feed path 47 is formed in the head body 22 in place of the powder feed paths 29A, 29B, and 29C (refer to FIG. 18). The other structure of the laser cutting head 46 is the same as the structure of the powder laser welding head 21. A gas injection outlet of the gas feed path 47 is formed together with the laser outlet at an end face of a head body 22. A gas feed hose 48 connected to the gas feed apparatus 50 is attached to the head body 22 by metal fitting member 32. A cutting head scanning apparatus 49 has the same structure as that of a welding head scanning apparatus 23 of the powder laser welding apparatus 10. The laser cutting head 46 includes only the collimate lens 25 as a lens and includes no condensing lens. The cutting method of the reactor internal of the nuclear power plant of the present embodiment will be explained below by referring to FIGS. 15 and 16. The cutting method of the reactor internal of the present embodiment has the procedures of executing the cutting and exchanging operations of the tubular structure (step S8) in place of the repair and the prevention maintenance operation (step S4) among the steps S1 to S7 executed by the prevention maintenance method of the reactor internal according to embodiment 1. In the present embodiment, after the operation of the boiling water nuclear power plant is stopped, similarly to embodiment 1, the removal and transfer of the internal equipment in the reactor pressure vessel 1 (step S1), the installation of the aerial environment setting apparatus (step S2), and discharge of the water from the reactor pressure vessel and the setting of the aerial environment (step S3) are executed in order. Thereafter, the cutting and exchanging operations of the tubular structure are executed (step S8). The cutting and exchanging operations of the tubular structure include each process of steps S8A to S8G shown in FIG. 16. The cutting and exchanging operations of the tubular structure will be explained in detail by referring to FIG. 16. The oxide film formed on the surface of the tubular structure is removed (step S8A). In step S8, the oxide film including the radioactive nuclide formed on the surfaces of the in-core monitor housing 4 which is a tubular structure and a cutting object and a plurality of control rod drive mechanism housings 3 to which the laser cutting apparatus 45 is attached, these control rod drive mechanism housings 3 being adjacent to it, is removed by the decontamination operation (the grinding operation or chemical decontamination) similarly to step S4A in embodiment 1. The cutting operation of the tubular structure is executed (step S8B). The laser cutting apparatus 45 is used in the cutting operation. The laser cutting apparatus 45 is hanged by the ceiling crane similarly to the powder laser welding apparatus 10 at step S4C and descends down in the guide pipe up to the position of the upper end of one control rod drive mechanism housing 3 (for example, the control rod drive mechanism housing 3A shown in FIG. 19) adjacent to the in-core monitor housing 4 being the cutting object. The seating member 11 of the laser cutting apparatus 45 is seated on the upper end of the control rod drive mechanism housing 3. The control rod drive mechanism housing 3 on which the laser cutting apparatus 45 is seated is one of four control rod drive mechanism housings 3 adjacent to the in-core monitor housing 4 being the cutting object. The gas feed apparatus 50 of the laser cutting apparatus 45 is installed on the operation floor in the reactor building. The laser cutting head 46 is moved up to the position A (refer to FIG. 19) by driving the first motor, second motor, and third motor, and the laser outlet of the laser cutting head 46 is permitted to face a cutting position 51 of the in-core monitor housing 4. Since the in-core monitor housing 4 is cut off in the horizontal direction, the laser cutting head 46 is rotated in the axial direction of the control rod drive mechanism housing 3 by driving the third motor 38 of the swing drive apparatus 37 so as to set the laser path 27 horizontally. When the laser path 27 is set horizontally, the drive of the third motor 38 is stopped. Next, the laser oscillator is operated and the laser 28A (power density: 44 kW/mm2) with power of 1 kW generated by the laser oscillator enters the optical fiber 26. The laser 28A is spread by the collimator lens 25, becomes a laser 28B with a spot diameter D of 5.4 mm of a parallel beam, and enters the laser path 27. The laser 28B is irradiated from the laser outlet toward a cutting position 51 of the in-core monitor housing 4 which is a cutting object. In the position where the laser 28B is irradiated, the in-core monitor housing 4 is melted. In the position where the in-core monitor housing 4 is melted by the irradiation of the laser 28B, gas (for example, air) pressurized from the gas feed path 47 is jetted. This air is pressurized by the gas feed apparatus (for example, a blower) 50 and is fed to the gas feed path 47 through the gas feed hose 48. The pressurized air discharged from the gas injection outlet of the gas feed path 47 is jetted toward the melted position of the in-core monitor housing 4 and the melted metal of the in-core monitor housing 4 is blown off. The first motor is driven while performing the irradiation of the laser 28B from the laser outlet and the jetting of pressurized air from the gas injection outlet. As a result, the support body 13 and the rotator 16 are rotated and the arm 17 is rotated in a predetermined angle in the horizontal direction around the rotary shaft 35. As a result, the cutting head 46 positioned in the position A (refer to FIG. 19), the cutting head 46 including in the laser cutting apparatus 45 seated in the control rod drive mechanism housing 3A, rotates horizontally in a predetermined angle around the rotary shaft 35 of the laser cutting apparatus 45 seated in the control rod drive mechanism housing 3A (refer to FIG. 19). Therefore, while melting the in-core monitor housing 4 by the laser 28B within the range of 45° each, that is, 90° in total (¼ of the overall periphery of the in-core monitor housing 4) on both sides in the horizontal direction of the straight line connecting a center of the control rod drive mechanism housing 3A and a center of the in-core monitor housing 4 which is a cutting object, the melted metal of the in-core monitor housing 4 is blown off by the pressurized air. After all, ¼ of the overall periphery of the in-core monitor housing 4 is cut off. The wire hanged from another travelling carriage installed on the ceiling crane is attached to an upper end portion of the in-core monitor housing 4. After completion of the cutting of ¼ of the overall periphery of the in-core monitor housing 4 by the cutting head 46 positioned in the position A (refer to FIG. 19), the laser cutting apparatus 45 seated on the control rod drive mechanism housing 3A is hanged up by the ceiling crane through the guide pipe disposed right above the control rod drive mechanism housing 3A and reach above the radiation shielding cover attached to an upper end portion of the reactor pressure vessel 1. In the present embodiment, four guide pipes are separately disposed right above four control rod drive mechanism housings 3 adjacent to the in-core monitor housing 4 being the cutting object and are attached to the radiation shielding cover at step S2. The laser cutting apparatus 45 which reached above the radiation shielding cover is come down in the guide pipe disposed right above the control rod drive mechanism housing 3B positioned in the neighborhood and is seated on the upper end of the control rod drive mechanism housing 3B. The first motor, second motor, and third motor 38 are driven, and the laser cutting head 46 is moved up to the position B (refer to FIG. 19), and the laser outlet of the laser cutting head 46 is permitted to face the cutting position 51 of the in-core monitor housing 4. While performing the irradiation of the laser 28B to the in-core monitor housing 4 and the jetting of pressurized air, the laser cutting head 46 arranged in the position B is rotated along the outside surface of the control rod drive mechanism housing 3B within the range of 45° each, that is, 90° in total (¼ of the overall periphery of the in-core monitor housing 4) on both sides in the horizontal direction of the straight line connecting a center of the control rod drive mechanism housing 3B and the center of the in-core monitor housing 4 which is a cutting object. Therefore, ¼ of the overall periphery aforementioned of the in-core monitor housing 4 facing the outside surface of the control rod drive mechanism housing 3B is cut off. After completion of the cutting of the in-core monitor housing 4 by the cutting head 46 positioned in the position B (refer to FIG. 19), similarly, the laser cutting apparatus 45 seated on the control rod drive mechanism housing 3B is hanged up by the ceiling crane and is seated in order at the respective upper ends of the control rod drive mechanism housings 3C and 3D positioned in the neighborhood. While performing the irradiation of the laser 28B and the jetting of the pressurized air from the laser cutting head 46, the laser cutting head 46 disposed in each the positions C and D is rotated along the outside surface of each the control rod drive mechanism housings 3C and 3D. Therefore, ½ of the remainder of the overall periphery of the in-core monitor housing 4 is cut off and the cutting of the in-core monitor housing 4 which is to be cut off finishes. After completion of the cutting of the in-core monitor housing 4, the laser cutting apparatus 45 seated on the upper end of the control rod drive mechanism housing 3D is pulled up by the ceiling crane through the guide pipe, is taken out from the reactor pressure vessel 1, and is transferred up to the operation floor. The cut tubular structure is taken out from the reactor pressure vessel (step S8C). The wire hanged down from another travelling carriage of the ceiling crane is wound and the in-core monitor housing 4, which is a cut tubular structure, above the cutting position 51 is pulled up through the guide pipe and is taken out from the reactor pressure vessel 1. A new tubular structure is transferred (step S8D). A groove portion in welding is formed at the upper end of the remainder of the cut in-core monitor housing 4 attached to the reactor pressure vessel 1 before an new in-core monitor housing 4A is transferred up to the upper end position of the remainder of the cut in-core monitor housing 4. The groove portion is formed as shown below. The upper end portion of the remainder of the in-core monitor housing 4 which is cut off is worked in order to form the groove portion by the cutting apparatus hanged down by the ceiling crane and descending through the guide pipe. The new in-core monitor housing 4A is held by the holding apparatus of a manipulator attached to the fuel exchange apparatus (not shown) moving on the operation floor in the reactor building, descends through the guide pipe, and is placed on the upper end of the remainder of the cut in-core monitor housing 4 with the groove portion worked by the cutting apparatus (refer to FIG. 20). The center of the new in-core monitor housing 4A and the center of the in-core monitor housing 4 attached to the reactor pressure vessel 1 coincide with each other and a central axial through these centers are extended upward in a straight line. The welding operation for the tubular structure is executed (step S8E). The powder laser welding apparatus 10 is hanged down by the ceiling crane and is seated on the upper end of one control rod drive mechanism housing 3 (among the four control rod drive mechanism housings 3A to 3D (refer to FIG. 21) in the neighborhood of the cut in-core monitor housing 4, for example, the control rod drive mechanism housing 3A). The first motor, second motor, and third motor 38 are driven, and the laser welding head 21 is moved up to the position A (refer to FIG. 21), and the laser outlet of the laser welding head 21 is permitted to face the welding positions 54 of the in-core monitor housings 4 and 4A. The laser welding head 21 is rotated in the axial direction of the control rod drive mechanism housing 3 by driving the third motor 38 of the swing drive apparatus 37 so as to set the laser path 27 horizontally. When the laser path 27 becomes horizontal, the drive of the third motor 38 is stopped. The laser 28A (power density: 44 W/mm2) with power of 1 kW generated by the laser oscillator enters the laser path 27 through the optical fiber 26 and the collimator lens. The laser 28B entering the laser path 27 is a parallel beam and the spot diameter D is 5.4 mm. The laser 28B is irradiated to the groove portions in the welding positions 54 of the in-core monitor housings 4 and 4A to melt the in-core monitor housings 4 and 4A. The metallic powder (for example, powder of the Inconel 52 alloy) which is a filler metal is fed to the powder feed paths 29A, 29B, and 29C of the head body 22 through the powder feed hoses 30A, 30B, and 30C, respectively, from the metallic powder feed apparatus 41. The total amount of the metallic powder fed to the powder feed paths 29A, 29B, and 29C is, for example, 0.17 g/W·s. The metallic powder is jetted from each powder injection outlet of the powder feed paths 29A, 29B, and 29C toward the welding place of the aforementioned groove portion and is melted in the fusion zone. While driving the first motor, performing the irradiation of the laser 28B to the groove portion and jetting the metallic powder, the laser welding head 21 is rotated horizontally in a predetermined angle around the rotary shaft 35 of the laser cutting apparatus 45 seated on the control rod drive mechanism housing 3A (refer to FIG. 19). Therefore, while the laser welding head 21 existing at the position A moves along the outside surface of the control rod drive mechanism housing 3A, the groove portion is melted by the laser 28B, and the metallic powder is melted in the fusion zone of the groove portion within the range of 45° each, that is, 90° in total (¼ of the overall periphery of the groove portion in the welding position 54) on both sides in the horizontal direction of the straight line connecting the center of the control rod drive mechanism housing 3A and the center of the in-core monitor housing 4 which is a welding object. The range of ¼ of the overall periphery of the groove portion is opposite to the outside surface of the control rod drive mechanism housing 3A. The in-core monitor housing 4 and the in-core monitor housing 4A are welded in the range of ¼ of the overall periphery of the groove portion in the welding position 54. Multi-layer welding is performed in the groove portion, so that the normal rotation and reverse rotation of the first motor are performed alternately and the laser welding head 21 for discharging the laser 28B and metallic powder is allowed to move back and forth within the range of ¼ of the overall periphery of the groove portion. After completion of the predetermined multi-layer welding within the range of ¼ of the overall periphery of the groove portion, the powder laser welding apparatus 10 seated on the control rod drive mechanism housing 3A is hanged up by the ceiling crane and is seated on the upper ends of the respective control rod drive mechanism housings 3 in order of the control rod drive mechanism housings 3C, 3B, and 3D as with the laser cutting apparatus 45. The laser welding head 21 is arranged in order in the positions C, B, and D. While the laser welding head 21 for discharging the laser 28B and metallic powder is moved along the outside surface of the control rod drive mechanism housing 3A within the range of each ¼ of the overall periphery of the groove portion opposite to each outside surface of the control rod drive mechanism housings 3C, 3B, and 3D, similarly to the case when the laser welding head 21 is arranged in the position A, the welding of the in-core monitor housing 4 and the in-core monitor housing 4A in the welding position 54 is performed. After completion of the welding of the overall periphery of the in-core monitor housing 4 and the in-core monitor housing 4A in the welding position 54, the powder laser welding apparatus 10 seated on the upper end of the control rod drive mechanism housing 3D is pulled up by the ceiling crane through the guide pipe, is taken out from the reactor pressure vessel 1, and is transferred up to the operation floor. The holding apparatus for holding the in-core monitor housing 4A is also raised up to the position of the fuel exchange apparatus by the operation of the manipulator. The grinding of the welding portion surface (step S8F) and the surface inspection (step S8G) after welding are executed. The grinding and the surface inspection are executed in sequence for the outside surface of the welding portion between the in-core monitor housing 4 and the in-core monitor housing 4A. The grinding of the welding portion surface at step S8F is performed similarly to step S4D of embodiment 1 and the surface inspection after the welding at step S8G is performed similarly to step S4E of embodiment 1. After completion of the surface inspection after welding at step S8G, each process at steps S5, S6, and S7 executed in embodiment 1 is executed in sequence. When the process at step S7 finishes, all the processes of the cutting method of the reactor internal of the nuclear power plant of the present embodiment finish. In the welding of the in-core monitor housing 4 and the in-core monitor housing 4A of the present embodiment, each effect generated in embodiment 1 can be obtained. Further, the laser cutting head 46 of the laser cutting apparatus 45 also includes only the collimate lens 25 as a lens, so that similarly to the laser welding head 21, the length of the laser cutting head 46 can be shortened. Therefore, the cutting of the in-core monitor housing 4 facing a narrow portion can be performed easily and the time required for the cutting operation can be shortened. Also at the time of cutting operation, there is no need to fit the cutting object to the focal position of the condensing lens, so that the cutting operation of the cutting object becomes easy. 1: reactor pressure vessel, 2: stub tube, 3: control rod drive mechanism housing, 4: in-core monitor housing, 10, 10A: laser welding apparatus, 11, 31: seating member, 13: support body, 15: pedestal, 16: rotator, 17: arm, 18: horizontal direction drive apparatus, 19: support member, 20: head holding member, 21: powder laser welding head, 22: head body, 23: welding head scanning apparatus, 24: lens housing, 25: collimate lens, 26: optical fiber, 28: laser, 29A, 29B: powder feed path, 35: rotary shaft, 36: hoisting table, 41: metallic powder feed apparatus, 44: bottom mounted instrumentation nozzle, 45: laser cutting apparatus, 46: laser cutting head, 47: gas feed path, 49: cutting head scanning apparatus, 50: gas feed apparatus.
	description	X-ray imaging uses the fact that x-rays xe2x80x9cRxe2x80x9d are extremely penetrating but are absorbed by the material xe2x80x9cBxe2x80x9d (such as a patient""s body) through which they pass. An x-ray image is the two-dimensional map of the x-ray absorption of the material xe2x80x9cBxe2x80x9d lying between an x-ray source located at a focal point xe2x80x9cFPxe2x80x9d and an X-ray detector located at a detector plane xe2x80x9cDPxe2x80x9d. FIG. 1 shows a typical medical x-ray imaging situation. The quality of the image depends on the fact that a significant fraction of the x-rays R are absorbed rather than scattered. Referring to FIG. 2, Ray R is emitted from the source located at the focal point FP and detected at point P by the X-ray detector located at the detector plane DP. Ray R1 scatters and is also detected at the point P. Ray R2 is totally absorbed and, therefore, not detected. In the making of an image, occurrences such as these happen many millions of times. The fact that R1 scattered and was detected at P causes density along the ray R1 to be appropriately assigned to the point P1. However, the point P receives radiation from the ray R1 and, therefore, the density along the ray R is measured to be lower than it actually is. Since scattering occurs in all directions, there is very little spatial information contained in the scattered radiation. The scattered radiation tends to blur the image and lower the measured absorption of localized regions of high absorption. This problem can be ameliorated by placing a grid 10 of plates 11, 12 in front of the X-ray detector DP which prevents the scattered radiation from reaching the detector, as shown in FIG. 3. The grid 10, which is also shown in FIGS. 4 and 5, is formed of a radiopaque material, such as lead, tungsten, copper or nickel. Each of these plates 11, 12 should be positioned so that the focal spot FP lies in the plane of the plate 11, 12. As illustrated in FIG. 3, it is clear that scattered radiation emanating from outside region (a) will not be detected; a fraction of the radiation emanating from the two regions labeled (b) will be detected; and all the radiation emanating from (c) will be detected. Furthermore, it is clear that this grid 10 will remove some of the unscattered radiation because the plates 11, 12 have a finite thickness xe2x80x9ctxe2x80x9d. For a one-dimensional grid, the geometric efficiency of the grid 10 is (pxe2x88x92t)/p where xe2x80x9cpxe2x80x9d is the period of the grid. For a two-dimensional grid, the geometric efficiency of the grid is ((pxe2x88x92t)/p)2. It is also clear that the effectiveness of the grid 10 in removing scattered radiation increases as the ratio h/p increases, where xe2x80x9chxe2x80x9d is the height of the grid 10 in the direction of the x-ray beam. Exemplary embodiments of the present invention provide techniques for making the focused anti-scatter grid 10 of FIGS. 3 through 5 efficiently and with high precision in those attributes which are important. The resulting grid structure is a sturdy and highly useful implement in the X-ray patient diagnostic imaging field, and provides the desired absorption of scattered secondary radiation. In addition, techniques conducted in accordance with the present invention can go to smaller characteristic dimensions, are relatively easier, less time-consuming and less expensive than existing techniques for making focused anti-scatter grids. One exemplary embodiment of a method (the exemplary embodiment of the method is illustrated as a flow chart labeled as reference numeral xe2x80x9c20xe2x80x9d in FIG. 6) according to the present invention for manufacturing the anti-scatter grid 10 having a desired height h (with reference to FIG. 3) and includes positioning a bottom surface of a mask of dielectric material, with a depth at least equal to the desired height of the anti-scatter grid, on a sheet of metal, as shown at 22 of FIG. 6. First and second series of intrinsically focused slots are then cut through a top surface of the mask to the sheet of metal, as shown at 24 of FIG. 6, and the sheet of metal is plated at the bottom of each of the slots of the mask with a radiopaque material to form partition walls of the anti-scatter grid, as shown at 26 of FIG. 6. Plating the radiopaque material into the slots of the mask is continued, as shown at 28 of FIG. 6, until the desired height h of the anti-scatter grid 10 (with reference to FIG. 3) is achieved. FIG. 7 a schematic illustration showing an exemplary embodiment of a method of plating the anti-scatter grid 10 of FIGS. 3 through 5 using the mask in accordance with the method of FIG. 6. The metal plate 1, on which the dielectric plating mask 2 is bonded, is immersed in an electrolyte 3 containing ions of the desired radiopaque material. An anode 4 of the same radiopaque material is placed in the electrolyte. The anode is connected to the positive terminal of a power supply 5 and the metal plate 1 (cathode), with the plating mask, is connected to the negative terminal. Positive ions are driven to the negatively charged cathode. By this technique, radiopaque material will build up in the slots resulting in a grid 10 of radiopaque material being formed. FIG. 8 is a flow chart illustrating an exemplary embodiment of a method 30 of cutting the mask 2 of FIG. 7 in accordance with the present invention. As the flow chart illustrates, the mask is cut by attaching the top surface of the mask to a steel xe2x80x9ccombxe2x80x9d having teeth forming a plurality of parallel slots, as shown at 32, mounting a conductor, such as a stranded copper wire, at the focal spot of the grid, as shown at 34, positioning the bottom surface of the mask on the detector plane, as shown at 36, connecting a high-resistance wire to the conductor and insulating the wire from the comb, as shown at 38, and pulling the high-resistance wire taunt, applying a charge through the high-resistance wire, and cutting the first series of intrinsically focused slots in the mask by passing the taunt, charged high-resistance wire along each tooth of the comb, as shown at 40. FIG. 8A illustrates an exemplary embodiment of an apparatus 100 that can be utilized in performing the electric machining of the method 30 of FIG. 8. The apparatus 100 includes an electrically insulated xe2x80x9ccombxe2x80x9d 102 having teeth 104 forming a plurality of parallel slots, which can attached to a top surface of the mask 2. The mask 2 is positioned on an imaginary detector plane DP and the apparatus 100 includes a first electrical connector 110 positioned at an imaginary focal spot FP, with reference to the imaginary detector plane DP. The first electrical connector 110 is fixed in position. The apparatus 100 also includes a second electrical connector 120, which is movable with respect to the first electrical connector 110, and an elongated high-resistance electrical conductor 130, such as a stranded copper wire, connected and pulled taunt between the first and the second electrical connectors 110, 120. As described previously, during a procedure wherein intrinsically focused slots are cut in the mask 2 with the apparatus 100, a charge is applied through the high-resistance wire 130 so that the wire is heated. Then the second electrical connector 120 is moved so that the taunt, electrified, high-resistance wire 130 is passed along each tooth 104 of the comb 102. The method 30 further includes attaching the metal sheet to the bottom surface of the mask, as shown at 42, detaching the comb from the top surface of the mask, as shown at 44, rotating the comb 90xc2x0 from its original orientation on the mask, as shown at 46, and reattaching the comb to the top surface of the mask, as shown at 48. Then the metal sheet is removed from the bottom surface of the mask, as shown at 50, and the second series of intrinsically focused slots is cut in the mask by passing the high-resistance wire along each tooth of the comb, as shown at 52. The metal sheet is then reattached to the bottom surface of the mask, as shown at 54, and the comb is detached from the top surface of the mask, as shown at 56. FIG. 9 is a flow chart illustrating another exemplary embodiment of a method 60 of cutting the mask 2 of FIG. 7 in accordance with the present invention. The mask comprises dielectric material which can be cut with a laser and dissolved with a solvent, as shown at 62, and is attached to the metal sheet, as shown at 64. The mask is cut by positioning the bottom surface of the mask on a xe2x80x9cdetectorxe2x80x9d plane, as shown at 62, positioning a mirror mounted on a two-axis gimbals at a xe2x80x9cfocalxe2x80x9d spot, as shown at 68, directing a laser beam off the mirror and onto the top surface of the mask, as shown at 70, and operating the mirror so that the first and the second series of focused slots are cut by the laser beam in the mask, as shown at 72. This laser should have enough power to cut through the mask. The laser and optics should be suitable to cut slots which are 100 microns or smaller. It may be useful to use a beam which is wide in the direction of the cut and very narrow perpendicular to the cut. This would allow much greater power to be applied to the mask; however, it would add complexity to the optics. The computer-controlled gimbals can be moved using standard motion control techniques either with servomotors, stepper motors, or other techniques such as piezoelectric actuators. Both coordinates must be controlled at the same time. Alternatively, the laser can remain fixed and the mask can be moved relative to the laser beam. A second option is to place a photomask in the laser beam, which will cast a shadow on the mask. This shadow is precisely in the form of the desired final plating mask. Using this technique, a much larger laser beam can be used which will cut many slots simultaneously. This beam will also be scanned from a single spot so that the slots, which are cut in the mask, converge on that spot. FIG. 9A illustrates an exemplary embodiment of an apparatus 200 that can be utilized in performing the laser cutting of the method 60 of FIG. 9. The apparatus 200 includes a laser source 202 and a mirror 210 mounted on a two-axis gimbal positioner 220. A two-axis gimbal positioner 220 provides titling movement with respect to two perpendicular axes, such as the x and y axes, as shown (two-axis gimbal positioners with motorized actuators are available, for example, from Microwave Instrumentation Technologies, LLC of Duluth Ga., http://www.mi-technologies.com, and Newport Corporation of Irvine Calif., http://www.newport.com). The mask 2 is cut by positioning the bottom surface of the mask on a detector plane DP, positioning the mirror 210 at the focal spot FP, directing a laser beam 204 from the laser source 202 off the mirror 210 and onto the top surface of the mask 2, and operating the two-axis gimbal positioner 220 so that first and second series of slots are cut in the mask 2 by the laser beam 204. A stainless steel (or other suitable metal) frame is attached to the aluminum sheet to provide a mounting means for the anti-scatter grid. The frame is connected electrically to the aluminum sheet so that during plating the anti-scatter grid is attached to the frame. The surface of the frame, which should not be plated, must be masked with a thick coat of wax. According to one exemplary embodiment, the metal sheet comprises aluminum and the mask comprises a fine grain styrene foam. The mask is secured to the metal sheet using hot wax, and the wax is scraped from the metal sheet at the bottom of each slot of the mask prior to plating. A lower surface of the metal sheet is coated with wax prior to plating. The mask is secured to the comb using hot wax, and the comb is heated to remove the comb from the top surface of the mask The surface of the aluminum sheet and the frame should be clean and free of contaminants so that a good bond can be achieved between the plated structure and the frame. If the surface of the metal to be plated is not perfectly clean, it may be necessary to etch it or clean it chemically or electrochemically in some way. When the aluminum plate with the plating mask and the frame are completed, they are placed in a plating bath. At this point, a radiopaque material is plated through the slots in the plating mask on to the aluminum of the backing plate and the stainless steel (or other suitable metal) of the frame. The plating continues until the grid is thick enough. At this point, the radiopaque material of the grid may be smooth and uniform, in which case the aluminum backing electrode may be dissolved in sodium hydroxide, or other agent for dissolving the metal sheet without dissolving the grid, the plating mask dissolved in an organic solvent, and the grid carefully cleaned. Alternatively, the metal sheet, can be provided as a very thin layer secured onto a thicker layer of radiolucent material, such as carbon fiber. In this manner, the combination of the thin layer of the metal sheet and the thicker layer of the radioluscent material can remain attached to the grid without substantially interfering the passage of x-rays through the grid. The metal sheet can also be provided as a very thin layer of a metal grid secured to a thicker support layer of radiolucent material. If the radiopaque material of the grid is uneven, the grid should be machined in some fashion to make it uniform. This is probably best done while the plating mask is still supporting the grid. After this, the aluminum electrode and plating mask are removed as explained above. When the grid is completely clean, a very thin layer of carbon fiber laminate or other suitable material may be glued to each face of the grid and the frame to protect and stabilize the grid. Alternately, the surface of the radiopaque material may be left rough so long as it is entirely within the slots of the plating mask. Furthermore, under some circumstances, the plating mask may be left in place since its absorption of x-rays is very small compared to that of the radiopaque material. It will thus be seen that the objects set forth above, and those made apparent from the preceding description, are efficiently attained and, since certain changes may be made in carrying out the above method and in the construction set forth without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. It is also to be understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.
	summary
	abstract	A mammographic imaging system is optimized for use with a single fixed size flat panel digital image receptor. It accommodates compression devices (paddles) of varying sizes, and positions them properly in the field of view of the image receptor. When a compression paddle with size smaller than the field of view of the image receptor is used, the compression paddle can be shifted laterally in the direction parallel to the chest wall, so as to facilitate different views of different size breasts, and permit the image receptor to image as much of the desired tissue as possible. An automatic x-ray collimator restricts the x-ray illumination of the breast in accordance with compression paddle size and location in the field of view. An anti-scatter grid, mounted inside the image receptor enclosure, just below the top cover of the enclosure, can be retracted out of the field of view of the image receptor for use in magnification imaging.
	description	This application represents the national stage entry of PCT International Application No. PCT/IB2012/001932 filed Aug. 28, 2012, which claims priority to Great Britain Patent Application 1115492.9 filed Sep. 7, 2011, the disclosures of which are hereby incorporated by reference in their entirety for all purposes. The invention relates to heat power engineering, in particular to methods that use a working medium for producing useful work from heat of an external source. A method for converting thermal energy of an external source into mechanical work is known (RU, 2078253, F03G7/06, 20.04.97) that increases the efficiency of a thermal generating set up to a value close to unity, i.e. up to complete conversion of heat into mechanical work. A method is known (RU, 2162161, F03G7/06, 20.01.2001) that provides the highest efficiency of a thermal generating set through complete conversion of the working medium heat generated by an external source into mechanical work. This method comprises interaction of the working medium with the thermal energy source, in particular, imparting thermal energy from the external source to the working medium flow, expansion of the flow by mechanical work, and performing energy exchange with an additional low-temperature thermal energy source, for the purpose of which a part of the general flow of the working medium having an increased density is used. This method actually implements the process of energy transmission inside the system “working medium—additional low-temperature energy source”. The method allows achieving the efficiency of thermo-mechanical transformations close to unity and using low-temperature thermal energy sources. However, this is possible only due to the application of a special, rather complex system of recovering thermal energy of the working medium expanded after the mechanical work is performed. A method is known according to international application WO 2004/046546 (Patent RU, 2213256, F 03G 7/06, 21.11.2002) that is most similar to the one being claimed and that comprises interaction of a working medium with an additional low-temperature thermal energy source in the form of the positron state of the Dirac's matter, said interaction performed by bringing the working medium into quantum-mechanical resonance with said state of matter. The energy transmission according to said method is carried out inside the system “working medium—positron state of the Dirac's matter”. The method is based on the comprehension of the positron state of the Dirac's matter disclosed in details in the study “The Principles of Quantum Mechanics by P.A.M”, Dirac, Second Edition, Oxford, 1935 [1]. The study asserts that the temperature of the said state of matter is close to −273° C., which allows considering said state as being close to the ideal low-temperature energy source, the so-called “physical vacuum”. Exposures of the working medium needed to create quantum-mechanical resonance cause polarization processes in the positron state of the Dirac's matter and generate two material particles, an electron and a positron, thereby confirming that “the physical vacuum is the fifth state of matter”. Further positron and working medium interaction releases energy, including that in the form of heat, which can be converted into useful work. The mechanism of phase transition of the working medium to the fifth state of matter during the quantum-mechanical resonance process with absorption or emission of a substantial amount of energy is disclosed in the studies “Mechanisms of First-Type Phase Changes in Metals and Semiconductors under the Influence of High Pressure and Electrostatic Field”, G. R. Umarov et al., High Pressure Physics and Engineering, 1990, No. 33 [2] and “Theory of Phase Transitions and Structure of Solid Solutions”, A. G. Khachaturyan, Moscow, Nauka, 1974 [3]. The above studies point out that in first-type phase transitions there are phase stability fields, in which fluctuations of the positron state of the working medium per se cannot lead to spontaneous creation of positrons and quantum-mechanical resonance with energy generation. The quantum-mechanical resonance occurs in the working medium that is on the verge of stable state and precedes phase transition, the development of which is conditioned by overcoming the state of absolute instability. However, the process of energy release in phase transition of the working medium overcoming the state of absolute phase instability develops like an avalanche. A short-term energy outbreak occurs, which does not always serve the task of the creators of the heat engine according to this method. In some cases a heat engine is required that performs work in a stable manner during a given period of time including a rather long one. The claimed method may be implemented, for example, in a heat engine in which the working medium (hereinafter called the substrate) may be, for example, InSb—TlSb alloy in the state of interaction with a thermal energy source. The functional diagram of a heat engine simulating set is given in FIG. 2. It comprises a target object—substrate 1 positioned in a thermostat 2 with a temperature and pressure controller, an apparatus 3 monitoring the state of the substrate (temperature, pressure, chemical and spectral composition, external fields, thermal capacity, thermal and electrical conductivities) with high accuracy, and an automatic control system 4 for controlling the variable parameter, which includes sensors of the value of the parameter being measured or of its change rate, and a data-processing device 5. The target object is a substrate in the form of the above-mentioned InSb—TlSb alloy in a state close to phase transition. Near the dielectric-metal phase transition, the state of the substrate is determined by proportions of its constituent elements selected according to a technique described in the study “Structural Stability and Trends in Band Structures of Covalent-Ionic Compounds”, Altshuler A. M., Vekilov Y. K., Umarov G. R., Pfys. Stat., sol (B)—1975—69, No. 2—pp. 661-670 [6]. A phase diagram of states in the vicinities of the triple point is constructed for the selected substrate composition. The value of fluctuations in the vicinity of the line of absolute instability is determined by calculations or experimentally. The temperature of the substrate, as one of the thermodynamic parameters, is set to be close to the point of the expected phase transition in compliance with the state diagram. Fluctuations of the basic thermodynamic parameters of the substrate as a system can be calculated by formulae derived and justified in publication: L. D. Landau, E. M. Lifshitz “Course of Theoretical Physics, Statistical Physics”, Vol. 5 (3rd ed), Butterworth-Heinemann, ISBN: 978-0-750-63372-7 [7]. Δ ⁢ ⁢ V 2 _ = - kT ⁡ ( ∂ V ∂ p ) T , ⁢ Δ ⁢ ⁢ T 2 _ = - kT 2 C v Δ ⁢ ⁢ p 2 _ = kT ( ∂ V ∂ p ) s Δ ⁢ ⁢ S 2 _ = kC p The parameters are designated in the formulae as follows: V—volume of the substrate, p—pressure, T—temperature, Cv—thermal capacity at a constant volume, Cp—thermal capacity at a constant pressure, S—entropy, k—Boltzmann constant. The values of fluctuations can be determined experimentally with the help of the method of photometric diagnostics of phase transition based on changes in the optical properties of the substrate. The method comprises sensing the brightness spectra of external source light reflected from the substrate surface and subjecting the spectra to comparative computer analysis. A database is formed according to the analysis results, which includes the dependence of the spectral brightness density on the values of one of the thermodynamic parameters (temperature in the given example), and boundary values of the parameter are determined at the beginning of phase transition. Measurements are taken at different points of time, and the mean squared deviation of the thermodynamic parameter value from the nominal value is used as a variable characterizing the fluctuation level. The quantum-mechanical resonance with heat release can also be detected experimentally from abrupt changes in thermal or electric conductivities of the substrate. These phenomena accompany the occurrence of the quantum-mechanical resonance as of a state preceding phase transition in the substrate. At fixed atmospheric pressure and temperature values within instrumental tolerances, the phase state of the substrate correspondents to point F in the phase diagram (FIG. 1). When an estimated value of the variable parameter (temperature in this case) is achieved at a step not exceeding a predetermined value of fluctuations, phase transition is initiated in a small volume of the substrate. Further changes in the fluctuating volume of the substrate, which increases as the phase (point F) approximates the state of absolute instability (BD line), may be used as well as temperature fluctuations to perform feedback for the adjustable parameter, which in this case is temperature. The equation of state known from statistical physics (for an ideal gas):PV=RT, where: P, V, T—parameters of the working medium R—gas constant,demonstrates that when the value of one parameter fluctuates, fluctuations of the other parameters occur inevitably, and thus the feedback may be formed as well by using pressure changes of the substrate that accompany phase transformation, or generated quanta of external fields. The above-mentioned regulation of the variable parameter change step provides smooth approaching of the phase transition state by the substrate with initiation of quantum-mechanical resonance and avoiding its avalanche-type development. The phase transition process can be initiated by changing another thermodynamic parameter—pressure. In this case, the above-mentioned target object may be positioned under a press, while the pressure change step required for smooth overcoming of the line of absolute instability is also determined by the method described above. Precise adjustment of the thermodynamic parameter (temperature in this case) in the vicinity of the line of absolute phase instability can be provided by introducing feedback for the adjustable parameter with the help of a control signal proportional to the predetermined root-mean-square value of fluctuations of the variable parameter itself and of accompanying fluctuations of the other thermodynamic parameters of the working medium. For any thermodynamic parameter, fluctuations of this order converted into electrical fluctuations can be measured both by the oscillographic method and by gauges of electromagnetic and electrodynamics systems. Thus, the claimed method converts thermal energy into useful work with the efficiency close to the theoretical one, using in-depth processes in the working medium without application of highly technical energy recovery systems, stabilizes operation of a heat engine in time, and expands the range of useful work obtained through its implementation. Implementation of the claimed method may produce the following effects as collateral ones: nuclear transmutation of substance possible energy transmission to specified distances creation of gravitational propulsion, which confirms the connection between electromagnetic and gravitational interactions. The claimed method can be used in the industry that requires significant power consumptions during long periods of time, for example, in non-ferrous metal industry, where 80% of the product cost is the cost of the power consumption with simultaneous cooling of hot shops in hazardous production facilities. The method can also be used to create a highly efficient energy source in the transport sector, and in a number of other industries mentioned above.
051704250	abstract	An x-ray diagnostics installation has a primary radiation diaphragm disposed in the beam path of an x-ray tube, with the x-rays attenuated by an examination subject being processed through an image intensifier video chain, which includes an image memory. The primary radiation diaphragm is provided with sensors which generate an electrical signal corresponding to the position of the individual diaphragm components of the primary radiation diaphragm, these signals being supplied to a processing stage in the image intensifier video chain. The processing stage acts on the data stored in the image memory so that the effect of the diaphragm can be simulated, and included in the displayed image. The processing stage includes a control computer connected to the sensors, and a simulation circuit for simulating the effect of the primary radiation diaphragm.
	description	The subject application is a continuation of U.S. patent application Ser. No. 15/600,536, filed May 19, 2017, 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, both of which are incorporated by reference herein in their entirety 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 keVdeuterium 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,ω02<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 , Δ ⁢ ⁢ β ⪡ 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 i ⁢ ⁢ n ≈ 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 Ø300μ 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 ηi 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.
	claims	1. A neutron absorber apparatus for a nuclear fuel storage system, the apparatus comprising:a fuel rack comprising a vertical longitudinal axis and plurality of longitudinally-extending storage cells, each cell comprising a plurality of cell sidewalls defining a cell cavity configured for storing nuclear fuel therein;a sheath integrally attached to a first cell sidewall of a first cell and defining a sheathing cavity configured for holding a neutron absorber material;an absorber insert comprising plural longitudinally-extending neutron absorber plates each comprising a neutron absorber material, the insert disposed in the first cell; andan elastically deformable locking protrusion disposed on one of the absorber plates, the locking protrusion resiliently movable between an outward extended position and an inward retracted position;the locking protrusion lockingly engaging the sheath to axially restrain the insert and prevent removal of the insert from the first cell. 2. The neutron absorber apparatus according to claim 1, wherein the locking protrusion engages a bottom edge of the sheath. 3. The neutron absorber apparatus according to claim 2, wherein:the locking protrusion is movable from the outward extended position to the inward retracted position by engagement between the locking protrusion and a top edge of the sheath when the insert is initially inserted into the first cell; andwherein the locking protrusion is movable from the inward retracted position back to the outward extended position to lockingly engage the bottom edge of the sheath when the locking protrusion is positioned at an elevation below the sheath when the insert is fully inserted into the first cell. 4. The neutron absorber apparatus according to claim 1, wherein the locking protrusion is a metal spring clip having a lower fixed end portion attached to the absorber insert and an upper cantilevered free end portion that is engaged with the sheath. 5. The neutron absorber apparatus according to claim 1, wherein the locking protrusion is disposed proximate to a lower end of the insert. 6. The neutron absorber apparatus according to claim 1, wherein the absorber insert has a four-sided tubular configuration formed by an assembly of a longitudinally-extending first absorber plate and second absorber plate. 7. The neutron absorber apparatus according to claim 6, wherein the first and second absorber plates are coupled together at their upper and lower extremities by respective upper and lower stiffening bands attached to the plates. 8. The neutron absorber apparatus according to claim 6, wherein the absorber insert defines a longitudinally-extending central cavity holding a fuel assembly therein. 9. The neutron absorber according to claim 7, wherein each of the first and second absorber plates has a chevron cross-sectional shape. 10. The neutron absorber apparatus according to claim 7, wherein each of the first and second absorber plates has a channel cross-sectional shape. 11. The neutron absorber apparatus according to claim 6, wherein longitudinal edges between the first and second absorber plates are separated by longitudinally-extending slots that extend for a full length of the absorber insert. 12. The neutron absorber apparatus according to claim 2, wherein the locking protrusion is disposed proximate to a corner of the insert to engage a lateral end portion of the bottom edge of the sheath. 13. A neutron absorber apparatus for a nuclear fuel storage system, the apparatus comprising:a fuel rack comprising a vertical longitudinal axis and plurality of longitudinally-extending storage tubes each defining a cell, each storage tube comprising a plurality of tube sidewalls defining a primary cavity;an absorber insert insertably disposed in the primary cavity of a first storage tube, the absorber insert comprising a plurality of absorber plates arranged to form a longitudinally-extending neutron absorber tube having an exterior and an interior defining a secondary cavity configured for storing a nuclear fuel assembly therein, each absorber plate formed of a neutron absorber material;an upper stiffening band extending perimetrically around an upper end of the absorber tube, the upper stiffening band attached to the exterior of the absorber tube and protruding laterally outwards beyond the absorber plates to engage the tube sidewalls of the first storage tube;a lower stiffening band extending perimetrically around a lower end of the absorber tube and disposed at least partially inside the secondary cavity, the lower stiffening band attached to the interior of the absorber tube;wherein the absorber plates of the insert assembly are spaced laterally apart from the tube sidewalls of the first storage tube by the upper stiffening band forming a clearance gap therebetween. 14. The neutron absorber apparatus according to claim 13, further comprising a sheath integrally attached to one tube sidewall of the first storage tube and defining a sheath cavity configured for holding a neutron absorber sheet, the sheath disposed in the clearance gap between the absorber tube and the one tube sidewall of the first storage tube. 15. A neutron absorber apparatus for a nuclear fuel storage system, the apparatus comprising:a fuel rack comprising a plurality of longitudinally-extending storage cells, each cell comprising a plurality of cell walls defining a cell cavity for storing nuclear fuel;a longitudinally-extending absorber tube insertably disposed in a first cell of the fuel rack and having an exterior and an interior, the absorber tube comprising:an elongated chevron-shaped first absorber plate comprising a first section and a second section angularly bent to the first section along a bend line of the first absorber plate;an elongated chevron-shaped second absorber plate comprising a third section and a fourth section angularly bent to the third section along a bend line of the second absorber plate;an upper stiffening band extending perimetrically around upper ends of the first and second absorber plates and coupling the first and second absorber plates together; anda lower stiffening band extending perimetrically around lower ends of the first and second absorber plates and coupling the first and second absorber plates together,wherein the upper stiffening band is attached to the exterior of the absorber tube and the lower stiffening band is attached to the interior of the absorber tube. 16. The neutron absorber apparatus according to claim 15, wherein the upper stiffening band laterally protrudes beyond the absorber tube and engages the cell walls of the first cell, the absorber tube spaced apart from the cell walls thereby forming a clearance gap therebetween. 17. The neutron absorber apparatus according to claim 16, further comprising a sheath integrally attached to a first cell wall of the first cell and defining a sheath cavity configured for holding a neutron absorber sheet, the sheath disposed in the clearance gap between the absorber tube and the first cell wall. 18. The neutron absorber apparatus according to claim 17, further comprising a laterally protruding cantilevered spring clip attached to one of the first and second absorber plates, the spring clip disposed proximate the lower stiffening band and lockingly engaging the sheath which prevents axial removal of the absorber tube from the first cell.
	summary
043127088	summary	FIELD OF THE INVENTION This invention relates to closure members for nuclear reactors and, more particularly, to stud hole plug units or other plug units for reactors requiring temporary or semi-permanent seals. DESCRIPTION OF THE PRIOR ART During the refueling operation in a nuclear reactor, the closure head assembly or reactor head, which is connected to the reactor vessel, is removed and the reactor vessel is flooded with a liquid such as a boric acid solution to prevent radiation from escaping while the fuel cells are being replaced. The closure head assembly is secured to the reactor vessel by a large number of studs extending around and through the closure head assembly for threaded engagement into the wall of the reactor vessel. When these studs are removed, it is necessary to plug the stud holes in the reactor wall during refueling so that corrosion does not occur within the stud holes. Presently, plugs are used which are generally complex in construction and include O-ring seals. However, these O-ring seals are not always reliable and leakage into the stud holes has occurred. Other standard closure members cannot be employed if they include metal expansion grips since the metal grips can damage the side of the opening into which the studs are reinstalled after the fueling operation has been completed. The down time on a nuclear reactor is extremely expensive and it often takes as long as two weeks to complete refueling. Therefore, since the stud hole plugs must perform for periods of time up to two weeks or longer, and unnecessary delays merely add to the already expensive down time, it is necessary that a dependable and reproducible seal be formed. Other applications for nuclear reactors in which the stud hole plug or the like can be used may involve a pressurized cavity such as with an inert gas to protect threads or the like and, therefore, reproducible and predictable sealing results are mandatory. SUMMARY OF THE INVENTION My stud hole plug provides a positive seal and a predictable and reproducible seal from unit to unit. In addition, my stud hole plug resists etching and corrosion and can be used to close off a pressurized cavity. My invention is a reactor stud hole plug unit comprising a compression plate, a mandrel, an elastomeric ring and a tightening means such as a nut. The compression plate includes an inner and outer surface, a peripheral edge, a central opening therethrough and an annular rim extending outward from the inner surface and spaced inward of the peripheral edge. The compression plate is dimensioned so that the peripheral edge rests on the reactor surface and the rim extends into the opening to be plugged. The mandrel has a centrally threaded stud extending outward through the compression plate. The mandrel has a cylindrical upper section and cylindrical lower section joined by a frustoconical connecting section. An elastomeric seal ring having a rectangular cross section snugly fits about the cylindrical upper section of the mandrel plate and engages the compression plate rim in aligned relationship. As the nut is tightened, the mandrel moves linearly toward the compression plate causing the seal ring to be forced along the conical section. When the compression plate bottoms on the mandrel, the seal ring has been forced to a position substantially planar with the bottom surface of the lower cylindrical section.
	description	The present application is a 35 U.S.C. §§371 national phase conversion of PCT/EP2008/063414, filed Oct. 7, 2008, which claims priority of French Application No. 0758144, filed Oct. 8, 2007, incorporated by reference herein. The PCT International Application was published in the French language. The present invention relates to a device for inspecting a fuel assembly in a pool of a nuclear plant equipped with a grapnel for displacing and suspending the assembly in the pool. It also relates to an inspection method applying the device. FIG. 1 schematically illustrates one of the racks 30 for storing assemblies 3 of fuel rods arranged in a storage pool 1 of a nuclear plant of the PWR (pressurized water reactor) type. Each assembly 3 forms an elementary fuel unit and should be placed in a nuclear reactor in order to be able to produce energy. Each assembly 3 is formed with a series of supporting and separating grids, in which cylindrical rods containing pellets of enriched uranium oxide are positioned vertically. Each assembly generally has a square cross-section (with a side of about 200 mm) grouping, for PWR operated by EDF, 264 rods (geometry 17×17) and a height of the order of 4-5 m. End pieces 31 and 32 respectively form the top and the base of the assembly. The racks 30, located at the bottom of the pool 1, include cells 34 with separating walls 33, so that no nuclear reaction occurs in the pool 1 when the assemblies 3 are placed in the racks 30. The so-called storage pool 1 forms a temporary storage lock for new assemblies 3 awaiting to be loaded into the nuclear reactor, and for spent assemblies awaiting removal (reprocessing, long period storage, etc.). The pool 1 is moreover filled with borated water 2, in order to avoid any nuclear reaction and any radiation towards the outside of the pool. In order to displace the assemblies in the pool, for example for loading them into the reactor, or for unloading them from the reactor, or for examining them, a mobile grapnel 4, connected to a bridge 8 located above the pool, allows the assemblies 3 to be grasped by their top and to be taken out of the cells 34. A lowerator 6 allows new assemblies to be put into the water. The lowerator 6 notably includes a basket 63, the length of which is generally at least equal to the length of an assembly 3, and in which an assembly is placed; this basket is mounted on a vertical rail 61 and actuated by a winch which allows it to be displaced along an axis Z parallel to a longitudinal axis of the assembly. A transfer machine as for it allows transportation of the fuel assemblies from the reactor towards the pool 1 (and vice versa). A discharge ditch then allows transportation of the assemblies towards reprocessing plants. In order to study or confirm the behavior under irradiation of the fuel assemblies, the possibility of inspecting the assemblies notably by metrology is desired. FIG. 1 very schematically shows a known inspection device 10. The device 10 is laid at the bottom of the pool or secured to the wall of the pool. It mainly includes a vertical enclosure 101 a little larger than the assembly, an enclosure open on one side in order to allow inspections. The fuel assembly is placed in this enclosure 101 by means of the bridge and of the grapnel 4. A video camera 102 mounted on the enclosure 101, may be displaced along the three axes (vertical 103, front/rear 105, left/right 104), in order to allow viewing of one face of the assembly. The camera is displaced by means of stepping motors 113, 114 and 115, the movement of which is indexed. A device placed at the bottom of the enclosure allows rotation of the assembly in order to allow successive examination of the four faces. In order to carry out the inspection of an assembly, the assembly 3 is removed from a cell of the rack 30 by means of the bridge 8, and then the assembly 3 is placed in the enclosure 101. Measurements are carried out by displacing the camera 102 in the space in order to successively aim at both of the ends of each length to be measured; the indexation of the stepping motors has been calibrated beforehand on a standard with a reference length; the covered distance may therefore be inferred from the information given by the motors 113, 114 and 115. EP 0 123 597 discloses an exemplary device, the operation principle of which is close to the known device described above. The device of EP 0 123 597 includes means for supporting the assembly to be examined, means for examining the assembly, including a camera, and means for displacing the examination means. Like for the device of FIG. 1, the fuel assembly should be mounted in the supporting means, prior to the measurements, for example by means of the grapnel already described. The means for displacing the examination means include a mobile carriage, a column integral with the carriage, and a bracket vertically displaceable along the column. These specific displacement means are mounted in proximity to the supporting means. Displacement counters are associated with the carriage and with the bracket in order to quantify the displacements of the camera. Measurements require a preliminary step for calibrating the displacement counters. Calibration is carried out by observing with the camera a reference graduation attached on the supporting means in proximity to the assembly. Once the displacement counters are calibrated, the measurement is conducted by successively aiming the camera at two ends of the length to be measured on the assembly: the displacement of the displacement means then provides the length to be measured. Known devices of the state of the art however have drawbacks. The known devices require the supply of specific additional pieces of equipment with respect to normal operation of the nuclear plant. These specific pieces of equipment are notably the enclosure 101 or the supporting means of EP 0 123 597, as well as the means for displacing the examination means. Such means may also be installed permanently, then requiring investment for each reactor. Known devices are thus relatively bulky. Their presence in the pool may interfere with certain handling operations, such as removal of the used fuel for example. The enclosure or the supporting means are moreover heavy. They have to be transported on the nuclear plant and installed in the pool for storing spent fuel. The transport and installation are costly operations which require significant time (one to two weeks). Measurements take a long time, since the camera has to move in order to explore each of the components, the length of which is intended to be measured. The phase for calibrating the displacement counters also takes a long time. The device includes a lot of elements and is not easy to decontaminate. The cost of the device is further relatively high. As the inspections are generally carried out during the renewal of the fuel, with a stopped reactor, the duration of the inspection may have a significant financial impact on the operating cost of the reactor. The invention proposes to overcome at least two of these drawbacks, i.e. the application cost and duration, without degrading the measurement accuracy. For this purpose, according to the invention, an inspection device according to claim 1 is proposed. The invention is advantageously completed by the features of claims 2-11. The invention also relates to a method for applying a device according to the invention. For this purpose, an inspection method according to claim 12 is proposed according to the invention. The present invention has many advantages. The invention only requires little specific hardware. No provision is made for heavy and bulky supporting means or for means for displacing the image sensor. Indeed, the function of supporting the fuel assembly (on which an inspection device is removably fastened according to the invention) during the taking of snapshots is performed by the bridge, which is a piece of equipment already present in a nuclear plant. Further, the means for displacing the image sensor are formed by the lowerator, which is a piece of equipment already present in a nuclear plant. The boom bearing the reference graduation of the device is, as for it, lightweight and not very bulky. The device is assembled and disassembled rapidly (about 4 hrs). The device may be installed in less than one hour, since its handling is easy: the boom is lightweight and mobile, and removable fastening of the boom on the assembly is carried out within a few minutes. This removable fastening is facilitated by the use of a float, which facilitates placement of the boom on the assembly, but which also makes the boom free of any tie since it floats when it is not fastened to the assembly. With the fastening accuracy of the boom on the assembly (1-2 mm), good accuracy of the measurements may be obtained. It is easily decontaminated. It is inexpensive. The snapshots are taken rapidly, so that the assemblies are only immobilized for a short time. Indeed, in order to take a snapshot, it is sufficient to lift the assembly out of its cell by means of the grapnel and to place it in front of the shooting device (at a distance of the order of 2 m). During the shooting, the assembly is always immersed in the pool, but is suspended from the bridge. Each assembly is thus immobilized for less than four hours for a total number of shooting points of about 850 (on the four faces of the assembly). The measurements are conducted off-line, and directly on the snapshots of the assembly and of the reference graduation, which increases the accuracy of the measurements. Indeed, because the means for displacing the image sensor are formed by the lowerator of the pool, the measurement based on displacement counters is no longer possible. On the other hand, the preliminary calibration phase is suppressed, which means additional gain in the time for taking snapshots. Further, as the measurements are conducted off-line on the snapshots, and no longer directly by displacing the camera, the immobilization time of the assembly in the pool is strongly reduced: it in fact boils down to the time for taking sequences of snapshots. The device allows complete inspection of the assembly. With it, it is notably possible to determine easily and directly: the distance between the end pieces, the distance between the peripheral rods and each end piece, the length of the peripheral rods, the height of the springs of the upper end piece, the offset distance between the end pieces, the altitude of each grid, the deflection of each grid, the width of each grid, and the space between the rods. The measurements accuracies are of the order of plus or minus 1 mm for large distances (from 4-5 m) and of plus or minus 0.25 mm for small distances (less than 100 mm). This is made possible by the use of a high precision image sensor (a digital camera instead of a camera with lower resolution associated with displacement counters as in the prior art). Taking of snapshots on the irradiated assemblies is ensured in the pool at combustion rates which may exceed 60 GWd/tU: protection against irradiation is ensured by a thickness of borated water of more than 2 meters between the device and the fuel assembly suspended from the bridge. The snapshots may be taken down to a depth of 12 meters, in borated water, at temperatures comprised between 15° C. and 50° C. In all the figures, similar elements bear identical numerical references. FIG. 2 schematically illustrates a possible example of a device for inspecting a fuel assembly 3 in a pool 1 of a nuclear plant. The device mainly includes an image sensor 5 and a boom 81. The sensor 5 includes a field of observation 53. The boom 81 includes at least one removable fastener to the assembly 3, and a reference graduation 84 extending along an axis Z parallel to a longitudinal axis Z′ of the assembly 3. The graduation for example consists of located divisions with a gap of the order of 1 mm for example. Other gap values may of course be provided. Preliminary metrology enables the position of certain reference divisions to be known with high accuracy (±0.2 mm). The boom 81 is removably fastened by fastening means 85 and 86, on the assembly 3, so that the image sensor 5 may observe in its field 53, both the boom 81 and the assembly 3. As shown by FIG. 2, the boom 81 is removably fastened onto the assembly 3, while the assembly 3 is borne by a grapnel 4 of a bridge and suspended from the bridge at an intermediate depth in the pool 1. Thus, with the invention, it is possible to do without heavy and bulky supporting means: the support of the assembly is ensured by the grapnel 4, already present in the installation. Fastening of the boom 81 onto the assembly is carried out with an accuracy from 1-2 mm. The measurement principle consists of determining, for each end of the large distances to be measured (for example the distance between the end pieces, the offset between the end pieces, the altitude of a grid of the assembly, etc.), the distance between this end of the assembly and a division of the graduation 84, parallel to the distance to be measured. For small distances to be measured (for example the distance between a rod and each end piece, the height of a holding spring, the deflection of the grid, the width of the grid or the space between two rods for example), the measurement is directly conducted on a single snapshot, the magnification of the image being determined by a portion of the graduation located in the snapshot taking field 53. To do this, the image sensor 5 acquires a snapshot with high magnification and high definition, with the end of the distance to be measured on the one hand, and the closest division of the graduation 84 on the other hand, in its field of observation 53. The measuring technique is then carried out off-line on the snapshot, by means of processing and control means 7 described in more detail in the following of the present description. Preferably, the image sensor 5 is a digital still camera 52 with automatic focussing, provided with a motorized telephoto lens 521 with variable focal length. Very preferentially, the camera 52 is comprised in a sealed cylinder 54 (up to 10 bars) equipped on the front face with an optical glass 55. The cylinder 54 also includes a digital still camera 56 mounted on the viewfinder of the camera 52, a pressure sensor 57 for locating the altitude of the sensor 5, a lighting projector 58 and a spirit level 59 for adjusting the horizontality of the sensor 5. The image sensor 5 is mounted on a table 630. The table 630 is mounted on a basket 63, itself mounted on a generally vertical rail 61 parallel to the longitudinal axis Z′ of the assembly 3. The rail 61 and the basket 63 are part of a standard piece of equipment of the pool called a lowerator 6. The basket 63 may thus move on the rail 61 by the displacement means 65. The inspection device is therefore considerably simplified and made lightweight relatively to the device of the prior art. Provision is not made for specific means for displacing the sensor. The table 630 is capable of displacing the sensor 5 along several axes. Thus, the table 630 may displace the sensor 5 in a plane XY perpendicular to the axis Z (in other words along a horizontal axis parallel to the face of the assembly) on the one hand, and around an axis Y perpendicular to the Z axis (in order to be able to adjust the horizontality of its optical axis) on the other hand. Generally, the grapnel 4 places the assembly 3 and therefore the boom 81, at a distance of about 2 meters from the lowerator 6 bearing the sensor 5. The boom 81 for example consists of a set of sections of booms, assembled with accuracy, being used as a framework. It includes two ends, an upper end 811 and lower end 812 respectively. The lower end 812 is connected to a removable fastener 85 to the assembly. The fastener 85 includes a receptacle 851 of the base 32 of the assembly 3. The receptacle 851 substantially has a complementary shape of the base 32, with edges 852, so that once it is in place, the fastener 85 is relatively stable, but always removable. Because of the shape of the receptacle 851, placement and removal of the fastener 85 are easy. At a suitable intermediate altitude, the boom 81 is equipped with a fork 86 capable of being removably fastened to a top 31 of the assembly. Similarly to the receptacle 851, the fork 86 substantially has a complementary shape of the top 31. The fork 86 is placed and removed easily, while being relatively stable once it is placed. The position of the fork 86 relatively to the boom 81 is adjustable and consequently the device may be adapted to different lengths of assemblies such as for example 4 m (900 MW) of 5 m (1,300 MW). The upper end 811 is further preferentially connected to a float 82 which balances the weight of the boom 81, which facilitates handling of the boom, while exerting a slight vertical thrust ensuring its hold on the assembly. The float 82 also allows floating of the boom 81 in the pool 1 when it is no longer fastened to the assembly 3 once the measurements have been conducted. Preferably, the graduation 84 includes a tape measure 841 ballasted with a weight 842. The boom 81 also preferentially includes a plumb line 87. It is recalled that the device includes processing and control means 7. The means 7 allows processing of the snapshot acquired by the image sensor 5. They also include a digital transmission chain 51 between the camera 52 and the processing and control means 7. The chain 51 is for example a USB type wire connection. The processing and control means 7 are for example a microcomputer. The means 7 are preferentially equipped: with software for controlling the camera 52 (generally provided with the camera 52), with a control interface for the table 630 and the projector 58, with snapshot software allowing import, viewing, naming and memory storage of all the snapshots required for the complete metrology of the assembly 3, with measurement software allowing all the measurements to be conducted from metrologies obtained on the snapshots acquired earlier, with software for formatting the measurement results (measurement report) and for technically controlling the measurements. All the measurements are conducted by metrology on an image, by measuring in pixels the distance between the target on the assembly and the graduation. The calibration of the magnification of the photograph is carried out directly by proportionality, from the graduation which is in the field. Therefore, there is no preliminary calibration.
056339011	summary	FIELD OF THE INVENTION The present invention relates to a permanent pool cavity seal for a nuclear reactor. BACKGROUND OF THE INVENTION A pressurized light water reactor operation is an established operation which is normally carried out with a high degree of reliability. In such reactors, a reactor vessel is positioned in a refueling pool cavity formed by a wall of the concrete shielding structure in a containment device. The refueling pool cavity has instruments positioned therein for monitoring reactivity. The refueling pool and the refueling pool cavity accomodate thermal expansion of the reactor during operation and provide a path for air flow from the bottom of the reactor vessel. Prior to refueling the reactor, the refueling pool is flooded with berated water to provide neutron shielding while the reactor vessel head is removed. To protect instrumentation in the refueling pool cavity, it is necessary to install a seal plate over the cavity before the water is added. During normal reactor operations the reactor vessel is subjected to radial and axial thermal expansion. Consequently, the seal plate currently in use for refueling operation can not be left installed around the reactor vessel and the refueling pool floor in the concrete shielding structure after refueling because it is unable to accomodate the thermal expansion of the reactor vessel. Attempts made at developing a permanent pool cavity seal, that does not require removal after refueling, have, as yet, not been completely successful. SUMMARY OF THE INVENTION The present invention provides a nuclear reactor containment arrangement wherein a permanent pool cavity seal extends across an annular gap between a reactor vessel having a peripheral wall and a horizontally extending flange, and a refueling pool wall which is a concrete shielding structure in the containment organization. The seal plate has a J-shaped flexible ring having an inner downwardly and then horizontally extending section welded at its inner periphery to an inner seal ring which is bolted and sealingly to the reactor vessel flange, and a support ring having an outer downwardly extending cylindrical section welded to an outer seal ring which is bolted and sealingly welded to a ring embedded in a refueling pool floor. The J-shaped flexible ring allows movement of the reactor vessel during thermal expansion and contraction. The permanent pool cavity seal which it provides, is strong and flexible. The permanent pool cavity seal, as it must be, is structurally strong enough to withstand the weight of the water and the impact of the heaviest object which might be dropped inadvertently thereon, without an ensuing a complete or sudden loss of shielding water, and, preferably, with the sealing integrity being substantially maintained. An inner portion of the seal plate overhangs the J-shaped flexible ring to protect it against an object being dropping thereon. The permanent pool cavity seal is also structurally flexible enough to accomodate the redial and the axial thermal expansion and contraction of the the reactor vessel relative to the concrete shielding structure during reactor operation, while substantially maintaining its sealing integrity. A cooperating access hole and access hole cover in the seal plate provide access to the refueling pool cavity. A plurality of support arms underneath the seal plate are provided. Each support arm may have at least a leveling screw to adjust the level of seal plate. This provides a permanent pool cavity seal which allows flooding of the refueling pool for refueling with it only being necessary to remove the access bole covers for normal reactor operations.
056617682	description	DETAILED DESCRIPTION A dry fuel transfer system generally comprises three main elements: the loading stand assembly which is placed partially under water in the spent nuclear fuel (SNF) storage pool and into which SNF rods or fuel assemblies are transferred; the transfer container which is landed on the loading stand and into which fuel assemblies are transferred from the loading stand assembly; and the discharge stack-up which includes a discharge stand onto which the transfer container is landed, and a transportation cask into which fuel assemblies are transferred from the transfer container. The transfer container 10 is shown in FIG. 1. It includes an integral hoist 12 attached to closure head 14, a main container body 16 and a shielded gate 18. FIG. 2 shows the container body 16 and closure head 14 in greater cross-sectional detail. The transfer container body 16 is preferably a cylindrical shell that is rabbeted at each end to fit with and fasten to closure head 14 and shielded gate 18 (FIG. 3). The fastening means (not shown for clarity) may be any conventional means such as a bolted flange joint. The container body 16 includes neutron shielding 21 (FIG. 2), a steel, exterior strength shell 20, shielding material 22 and a light steel, interior shell 24 that contains the radiation shielding material 22. Selection of the type of material 22 and thickness as defined by interior shell 24 will depend on the amount of radiation expected to be emitted by the particular fuel assemblies that will be carried in the transfer container. The interior of body 16 is provided with guide rails 26 that are attached at their upper end to closure head 14 and supported along their length by body supports 28. Guide rails 26 provide a locating sliding fit for a sliding sleeve 32 (see FIG. 11--omitted from FIG. 2 for clarity) that translates vertically within body 16. The exterior of transfer container body 16 has mounted thereon at least two lifting structures 44, well known in the art, located 180 degrees apart for hoisting and erecting the transfer container. As illustrated in FIG. 3, transfer container body 16 can be adapted to extend its length with the addition of one or more container body extensions 17, that also include extensions 27 for guide rails 26. This feature allows the transfer container to be easily adapted to accommodate varying lengths of fuel assemblies in a variety of applications. Closure head 14 (FIG. 2) forms the top of transfer container 10, provides mounting support for integral hoist 12 (FIG. 4) and holes with tight clearance fittings for the hoist cable 34 and grapple control cable 36 (FIG. 7). The closure head 14 is constructed the same as body 16 with neutron shielding 37, a steel, exterior strength shell 38, radiation shielding material 22 and a light steel interior shell 40 that contains material 22. The lower surface 42 of closure head 14 is cup-shaped with a rabbeted surface for mating with and extending over the upper end of body 16. The rabbeted fit ensures that radiation must pass through a sufficient amount of shielding to protect personnel. Two holes, or vertical channels, 46 and 48 pass through closure head 14 to provide tight clearance passage of hoist cable 34 and grapple control cable 36, respectively. These holes receive cables 34 and 36 through a seal assembly 52. The integral hoist 12 is shown generally in FIG. 1, but a preferred embodiment is shown in the several views of FIGS. 4 through 6. Hoist 12 is an electrically driven cable and drum hoist that is mounted on the top of closure head 14 via mounting plates 54. Hoist 12 includes two drums 55 and 57 that store the hoist lift cable 34 and the grapple control cable 36, respectively. Preferably, hoist 12 utilizes current art single-failure proof technology to ensure that the load lifted by the hoist is not dropped due to hoist failure. Cables 34 and 36 are delivered from the stowage drums 55 and 57 via pulleys 50, 53, and 51 and pass through seal assembly 52 and tight clearance passages or holes 46 and 48 of closure head 14 (FIG. 2). Hoist 12 includes motor 56 which, through gear box 58, drives the cable drum 55 directly and drum 57 indirectly through hoist cable 34 wound thereupon. Each of the drums 55, 57 are supported by drum mounting blocks 60. Motor 56 includes an integral rotary position encoder 64, shown only generally in phantom in FIG. 6, to provide data indicating the length of hoist cable 34 and/or grapple control cable 36 paid out from the cable drums. Position encoder 64 is connected electrically by cable to remote controller 66 to provide the length data to the controller and enable remote monitoring. Remote controller 66 is preferably a conventional computer with standard programming and input/output (I/O) capabilities. Note that for purposes of illustration, individual cables are shown connected between hoist 12 and remote controller 66 but in actual practice all cables would be routed so that only a single, multi-wire cable 67 (FIG. 1) would connect between the remote controller 66 and transfer container 10. Motor 56 is also connected to controller 66 via the same cable 67 to enable remote actuation of hoist 12. As an additional monitoring feature, the connecting shaft 68 to the cable drum 55 includes a strain gauge bridge 70, shown generally in FIG. 6, for detecting the size of the load attached to the hoist cable. Bridge 70 is connected electrically by the same multi-wire cable 67 to remote controller 66, which is programmed by conventional techniques to determine from the load detected whether one or more fuel assemblies have been latched or released by grapple assemblies attached to the hoist cable. Remote controller 66 is preferably provided with a control panel and/or display 72 that indicates to an operator the length of the cables paid out from the drums, the load carried by the hoist cable (e.g. in pounds), and other indicators to be discussed further hereinafter. Control panel 72 will preferably also provide control switches or dials for activating the hoist motor 56 to raise and lower the hoist cable and attached grapple assembly. As shown in FIG. 7, the hoist cable 34 is attached, within container body 16, to common grapple bracket 74 of grapple assembly 75 via connector 76. FIGS. 28-31 give a perspective view of the grapple assembly within body 16. Common grapple bracket 74 has attached thereto a number of grapples 78 for latching and releasing spent nuclear fuel (SNF) assemblies or rods 80 (see, for example, FIG. 30). FIG. 8 shows an embodiment of the present invention with four grapples 78 connected to four arms 82 of the bracket 74. Grapple control cable 36 (FIG. 7) is routed along or through arms 82 to each of grapples 78. Central post 84 of bracket 74 is provided with a locking ring 86 that is received in an opening 88 in closure head 14 (FIG. 2). Ring 86 automatically trips grapple locking mechanism 89 (FIG. 2) within head 14 via a pin, lug, key or other suitable tripping device. Mechanism 89, which may be pneumatically, electrically, hydraulically or mechanically activated and released, latches ring 86 in position in opening 88. Ring 86 can be locked in position in opening 88 to lock the grapple assembly 75 in its fully retracted position with (FIG. 31) or without (FIG. 28) fuel assemblies attached. Thus, the grapple assembly can be held in its fully retracted position independent of the hoist 12. Again with reference to FIGS. 7 and 8, a number of grapples 78 are connected to a respective number of arms 82 of common grapple bracket 74. Each grapple 78 functions to securely latch a fuel assembly 80, while it is hoisted into transfer container 10 and retained therein, while container 10 is moved, or while the fuel assemblies are lowered out of the transfer container and into a cask for storage or transport. Preferably, grapples 78 are actuated by electrical solenoids that are powered through grapple control and data cable 36. Pneumatic or mechanical actuation may also be employed. The control and data cable 36 is connected electrically to remote controller 66. This connection is shown for illustration purposes only in FIG. 6 with the control and data cable connector shown at 90. Preferably, however, all electrical cables will be routed within a single multi-wire cable with only a single multi-pin or multi-wire external connector for connecting with a single multi-wire cable 67 to controller 66. Each grapple 78 is individually actuated by remote controller 66 through operator action using control dials or switches on control panel 72. Panel 72 will preferably display indications of which grapples are actuated. Individual actuation of the grapples allow selective latching and hoisting in one embodiment, of only one, two, three or four fuel assemblies. This feature is useful in situations where, for example, one or two fuel assemblies are already contained in a storage or transportation cask and others are to be added from/to the transfer container. Grapples 78 are attached to the arms 82 of the common grapple bracket 74 by current art, commercially available, quick release fittings 79 and to the grapple control cable 36 by quick release connectors 81 so that the grapples 78 can be interchanged with another type of grapple suitable for different fuel assemblies. Thus, transfer container 10 can be readily reconfigured to suit various applications. FIGS. 9 and 10 illustrate an alternative or auxiliary common grapple bracket embodiment 74A with eight grapples 78 for holding up to eight fuel assemblies. Selection of a particular maximum number of fuel assemblies to be simultaneously maneuvered and held by transfer container 10 will depend on the particular application to which the present invention is applied. The fuel assemblies are lifted into and out of container body 16 while positioned in a sliding sleeve 32, which is best shown in FIGS. 11 and 12. Sleeve 32 is a box shaped structure that translates (slides) on guide rails 26 vertically within body 16. In its uppermost position (FIG. 28), the top of sleeve 32 is raised up to closure head 14, and in its lowermost position (FIG. 30) the bottom of sleeve 32 is lowered outside of transfer container 10. Sleeve 32 contains a number of runners 92 that slide on guide rails 26 (FIG. 2) of body 16. As best shown in FIG. 12, sleeve 32 is internally divided along its length by walls 94 to provide a number of compartments 96 configured to receive a corresponding number of fuel assemblies. Sleeve 32 is preferably constructed in a geometrical configuration that effects a spatial relationship between fuel assemblies appropriate to ensure subcriticality of the fuel assemblies while in the transfer container. Such configuration must be determined for each application (i.e. type, shape, etc. of fuel assemblies to be handled) of the present invention using techniques well known in the art. Alternatively, or additionally, sleeve 32 (including walls 94) is constructed of a material which may contain boron (neutron poisons) as a component. Sliding sleeve 32 includes an opening 98 at the intersection of walls 94 that serves as passage for the common grapple bracket 74, hoist cable 34 and grapple control cable 36. FIG. 13 illustrates an alternate or auxiliary sliding sleeve embodiment 32A configured to accommodate up to eight fuel assemblies. In FIG. 13, lifting plates 100 are removed to better illustrate the relationship of walls 94 and configuration of the eight compartments 96. Sleeve 32 is moved up and down by and in conjunction with grapple assembly 75. Sleeve 32 includes lifting plates 100 that engage, with their lower surfaces, the upper surfaces of common grapple bracket arms 82. When grapple bracket 74 is raised by hoist 12, it engages lifting plates 100 thereby raising sleeve 32. When the grapple assembly 75 is locked in its uppermost raised position within body 16, sleeve 32 is securely retained by the locked bracket 74. When the common grapple bracket 74 is unlocked and lowered by integral hoist 12, sliding sleeve 32 descends by gravity as it is lowered by the common grapple bracket. When the lower end of sliding sleeve 32 mates with the upper end of the loading stand fuel basket 102 (see FIG. 30), it aligns with the fuel basket. As best seen in FIG. 14, sliding sleeve 32 aligns with fuel basket 102 through cooperation of flange 33 that seats inside of flanged lip 103 of fuel basket 102. When aligned with the fuel basket, the sliding sleeve 32 guides the common grapple bracket 74 as it is further lowered by the integral hoist 12 until the grapples 78 contact the standard latching features of the fuel assemblies contained in the loading stand fuel basket 104 and are actuated to latch the fuel assemblies. As the integral hoist 12 raises the common grapple bracket 74 and the latched fuel assemblies, the sliding sleeve 32 remains mated and aligned to the fuel basket 104 providing locational control of the fuel assemblies as they are lifted. The fuel assemblies are lifted fully into the sliding sleeve 32 whereupon the common grapple bracket 74 engages the top of the sliding sleeve 32 and causes the integral hoist 12 to retract the sliding sleeve 32 with the latched fuel assemblies into the transfer container 10. FIG. 15 illustrates the interchangeability of auxiliary sliding sleeve 32A with standard sliding sleeve 32, and the interchangeability of auxiliary common grapple bracket 74A of grapple assembly 75 with standard common grapple bracket 74. The arrows show the removal of the standard sliding sleeve 32 and the installation of the auxiliary sliding sleeve 32A. The sliding sleeve and grapple assembly are lowered through and out of the transfer container body 16. At that position the sliding sleeve is not held by the guide rails. The common grapple bracket 74 is disconnected from the lifting cable 34 and the grapple control cable 36 is disconnected from its end fitting. The auxiliary common grapple bracket 74A and grapple control cable are connected to the lifting cable and grapple control cable end fitting, respectively. The auxiliary sliding sleeve 32A and common grapple bracket 74A are then raised into the transfer container body by the integral lifting hoist 12 while aligning the auxiliary sliding sleeve 74A onto the guide rails 26. Sliding sleeve 32 passes into and out of container body 16 through shielded gate 18. Gate 18, as shown in detail in FIGS. 16, 17 and 18, mounts to the lower end of container body 16 via a rabbeted fit (see FIG. 3, for example) and is connected to body 16 by a bolted flange or and other suitable fasteners. As best shown in FIGS. 16 and 17, gate 18 is constructed with a steel shell 104 that encloses shielding material 22. Gate 18 includes an opening 106 in its center that may be circular (as shown) or rectangular, but appropriately sized and shaped to allow passage of sliding sleeve 32 vertically through it. Mounted within shell 104 of gate 18 are two doors 108, 110, preferably semicircular (as shown in phantom in FIG. 18). Doors 108, 110 translate horizontally within gate 18 toward and away from one another to close and open, respectively, gate opening 106. Doors 108 and 110 each include a double stepped mating interface 112 and 114, respectively for creating a double seal when the doors are closed together. Seals 116 and 117 are provided for the mating and sealing faces of the doors so that the interior of the transfer container can be sealed and pressurized or purged with inert gas. Doors 108, 110 are actuated by an external power source such as gear motor 118 that drives a linked pair of opposed thread Acme type screws 120, 122. Gear motor 118 is preferably electrically connected to and controlled by remote controller 66, and remote control panel 72, preferably, provides an indication of the status (i.e. closed, open) of doors 108, 110. Shell 104 has connected thereto lips 124 (FIG. 18) each with an alignment hole 126 that mates with a corresponding pin that extends up from an adapter plate 128 (FIG. 22) on a loading stand assembly 132 (FIG. 19), as will be discussed in detail hereinafter. Holes 126 and the pins of the adapter plate ensure that transfer container 10 is properly aligned with the fuel basket in the loading stand when the transfer container is landed on the loading stand. Fuel assemblies, e.g. spent nuclear fuel (SNF) rods, are transferred into transfer container 10 from a spent nuclear fuel (SNF) storage pool 134 utilizing the loading stand assembly 132, as best shown in FIG. 19. The SNF storage pool 134 is typically located near a nuclear reactor to store spent fuel assemblies under water. As shown in FIG. 19, water W is maintained at a level L within the walls 136 of the pool. In order to transfer the spent fuel assemblies out of pool 134, loading stand assembly 132 is placed in the pool so that it is underwater except at its uppermost region. The loading stand includes a number of support columns 138 that provide the primary structural support for the assembly. Columns 138 are preferably adjustable in length by adding sections, e.g. lower sections 140 in FIG. 19, so that the loading stand assembly 132 extends from the floor F of the pool to the top of the pool. Columns 138 are tied together by bracing 146 and 174. As best shown in FIGS. 20 and 21, each support column 138 includes a pin 144 for engaging a corresponding hole 148 in loading stand adapter plate 128. Shims 142 (FIG. 21) are placed over pins 144 on top of columns 138 as necessary to level the loading stand adapter plate 128 when it is placed on top of the columns 138. Shims 142, which are thin disks or washers, permit the level of each of the four corners of the adapter plate to be adjusted to compensate for any unevenness in the floor F of the storage pool 134. Loading stand adapter plate 128 (FIG. 22) is mounted on top of the loading stand support columns 138 (see FIG. 19, for example) and may be shimmed at the mounting interface to level the adapter plate, as described above with reference to FIG. 21. Plate 128 includes a slot 150 to allow the pool fuel handling crane (not shown) to move fuel from storage racks (not shown) in the pool to the fuel basket 102 in the loading stand assembly. The center of plate 128 includes opening 152 that is dimensioned to accept the transition shield 154 and includes a lip 156 that supports transition shield 154, which is also slotted to permit movement of the fuel handling tool. Loading stand adapter plate 128 includes alignment pins 158 that are received in holes 126 of shielded gate 18 (FIG. 18) to properly align the transfer container 10 when it is loaded onto the loading stand assembly. Loading stand assembly 132 can be secured to withstand earth vibrations, such as seismic events, by deck anchored hold-down supports 178 attached on one end to the loading stand adapter plate 128 and appropriately anchored on their opposite end to the ground or a deck (not shown). The transition shield 154 is a shielded structure as best seen in FIGS. 19 and 22) that is open on the top and bottom and mounted within the loading stand support columns 138. A serpentine slot 151 is provided in the front of the shield to provide access for a fuel handling tool (not shown) to pass when transferring fuel assemblies into the fuel basket 102. The inner dimensions are sized to allow passage of the sliding sleeve 32 of the transfer container and entry from below of the fuel basket 102 as it elevates the fuel assemblies above the surface of the water for removal from the pool. The transition shield 154 is located such that its top is even with the top of the loading stand adapter plate 128. Part of the shield is below the pool water and part of the shield is above the water. In cross section its construction is generally similar to that of the transfer container body 16 and functions to provide radiation shielding for fuel assemblies as they are removed from the pool and drawn up through the shielded gate 18 into the transfer container. The fuel basket 102 as best shown in FIGS. 23 and 24 provides a number of compartments 160 for receiving fuel assemblies from the fuel storage pool fuel movement crane (not shown) as the fuel is moved from the fuel storage racks (not shown) in the storage pool. When the basket is loaded, the loading stand elevator 162 lifts the SNF basket vertically into the transition shield 154 and partially out of the water. The upper limit of travel is defined by the outer flange 164 of the basket 102 which mates with the bottom surface of the transition shield 154. As shown in FIG. 26, flange 164 of basket 102 includes alignment pins or bars 165 that are received in corresponding holes or channels 167 of transition shield 154 as basket 102 is raised in the direction of the arrows by the loading stand elevator. The upper surface of the basket provides a locating feature (i.e. flanged lip 103) which mates with and aligns the sliding sleeve 32 as it is lowered from the transfer container, as previously described with reference to FIG. 14. This aligns the grapples of the transfer container with the standard grapple points on top of the fuel assemblies within the basket. Basket 102 is preferably constructed in a geometrical configuration that effects a spatial relationship between fuel assemblies to ensure subcriticality of the fuel assemblies while in the basket and matches that of the sliding sleeve 32. Such configuration must be determined for each application (i.e. type, shape, etc. of fuel assemblies to be handled) of the present invention using techniques well known in the art. Alternately, or additionally, basket 102, (including walls 166) is constructed of a neutron absorbing material (neutron poisons), e.g. boron or material containing boron as a component. FIG. 25 shows an alternate or auxiliary embodiment 102A of the fuel basket that is capable of accepting up to eight fuel assemblies and matches the sliding sleeve 32A. The loading stand elevator 162 (FIG. 27) raises and lowers fuel basket 102 from a point above the floor F of the SNF storage pool up to the basket unloading position which is partially above the pool water and partially within the transition shield 154. Elevator 162, as best seen in FIG. 27, is preferably a cable drive system powered by an electrical hoist motor 168 which drives stowage drums 170 and linking mechanical drives 169 which are mounted to the underside of adapter plate 128. Motor 168 drives four hoist drums 170 that provide a balanced lift of fuel basket 102 as it is raised and lowered. Lift cables are channeled within the elevator guide slotted tubes 176 (FIG. 19). Basket 102 rides on and is guided by elevator guide tubes 176 that are passed through holes 180 in basket flange 164 (FIG. 24). The operation of the present invention will now be described in the environment of a nuclear site. Standard equipment and procedures are mentioned but not described in detail herein as such equipment and procedures are well known in the art. Prior to the commencement of spent nuclear fuel (SNF) transfer operations, the appropriate equipment is assembled both in the wet cask loading area of the site's SNF storage pool and in an appropriate dry cask loading area. The loading stand 132 is assembled and lowered into the site's SNF storage pool. A discharge stack-up is assembled in the designated dry cask loading area. An exemplary discharge stack-up is disclosed in U.S. Pat. No. 5,319,686, having the same assignee as the present patent application, and incorporated in its entirety herein by reference. To commence SNF transfer operations, the fuel assemblies 80 will be transferred from locations in fuel storage racks to positions in the fuel basket 102 of the loading stand. This transfer is accomplished by the use of the storage pool's standard fuel handling crane. An appropriate number of pressurized water reactor (PWR) or boiling water reactor (BWR) fuel assemblies 80, or other fuels or high level waste may be transferred into the fuel basket 102 each transfer cycle. The appropriate access hatches or doors to the storage pool building are opened and the transfer container 10 is brought into the storage pool area. The transfer container 10 is landed on the loading stand 132 (FIG. 28) while being properly located by the alignment pins 158 on the loading stand adapter plate 128. The movement of the transfer container may be accomplished by the use of an approved on-site crane. Once the transfer container 10 is seated on the loading stand 132, power, the remote controller 66 and the remote control panel 72 are connected to the transfer container and the electronic equipment is allowed to warm up. The remote control panel 72 and remote controller 66 are located in a low radiation area away from the transfer container to minimize personnel radiation exposure. The shielded gate 18 is then opened, via the remote control panel 72, providing an opening for the grapple assembly 75 and the sliding sleeve 32 to pass through. Prior to lowering the grapple assembly and sliding sleeve, the loading stand elevator 162 is activated and the fuel basket 102, with the fuel assemblies to be transferred, is raised to a height which ensures that the top of the fuel basket is above the surface of the storage pool water and within the transition shield 154 (FIG. 29). This reduces contamination of the grapple assembly and sliding sleeve while grappling fuel assemblies. With the fuel basket in the raised position, the transfer container grapple assembly 75 and sliding sleeve 32 are lowered, via the remote control panel 72, to rest atop the fuel basket and over the fuel assemblies (FIG. 30). The grapples are actuated remotely and latched to the fuel assemblies. Latching is confirmed by a series of electric sensors and the measurement of the proper weight is confirmed as displayed on the remote control panel. The grapple is designed to prevent the latching mechanism from releasing while the grapple is holding the weight of the fuel assembly. This ensures that inadvertent operation of a release button on the remote control panel, while raising or lowering the fuel assembly does not cause the grapple to release. Once latched, the grapple assembly, sliding sleeve, and all the fuel assemblies are raised into the transfer container. The sliding sleeve, which travels with the grapple assembly, ensures by proper fuel spacing that the fuel assemblies remain in a subcritical arrangement. In addition, the sliding sleeve is designed to protect the integrity of each fuel assembly and minimize any possible interference by continuously guiding each fuel assembly as it is removed from the fuel basket. Once the grapple assembly, sliding sleeve, and fuel assemblies are completely raised into the transfer container, the grapple assembly, with the fuel assemblies attached, is automatically secured in the transfer container. The loading stand elevator is activated to lower the fuel basket. The transfer container shielded gate is activated, via the remote control panel, to close and seal the bottom of the transfer container (FIG. 31). Then, the power and remote control panel are disconnected from the transfer container. Once the SNF basket is in its lower position, the transfer container is lifted off of the loading stand and moved to an SNF cask loading area by the on-site crane. The above process is then reversed to unload the fuel assemblies from the transfer container and into an SNF cask. The emptied transfer container is then moved back again onto the loading stand in the storage pool and additional fuel assemblies are loaded therein.
	description	1. Field of the Invention This invention relates in general to pressurized water nuclear reactors and, in particular, to systems for injecting additional coolant into the reactor coolant circuit in the event of a postulated accident. The invention is applicable to reactor systems having passive safety features with automatic depressurization of the reactor coolant circuit to facilitate the injection of additional coolant water. 2. Related Art A nuclear reactor, such as a pressurized water reactor, circulates coolant at high pressure through a coolant circuit traversing a reactor pressure vessel containing nuclear fuel for heating the coolant and a steam generator operable to extract energy from the coolant for useful work. A residual heat removal system is typically provided to remove decay heat from the pressure vessel during shutdown. In the event of a loss of coolant, means are provided for adding additional coolant. A coolant loss may involve only a small quantity, whereby additional coolant can be injected from a relative small high pressure make-up water supply, without depressurizing the reactor coolant circuit. If a major loss of coolant occurs, it is necessary to add coolant from a low pressure supply containing a large quantity of water. Since it is difficult using pumps to overcome the substantial pressure of the reactor coolant circuit, e.g., 2,250 psi or 150 bar, the reactor coolant circuit is depressurized in the event of a major loss of coolant so that coolant water can be added from an in-containment refueling water storage tank at the ambient pressure within the nuclear reactor system containment shell. The primary circuit of an AP1000 nuclear reactor system, offered by the Westinghouse Electric Company LLC, of which the present invention is a part, uses a staged pressure reduction system for depressurizing the primary coolant circuit, which is illustrated in FIGS. 1 and 2. A series of valves 72 couple the reactor outlet 56 (also known as the “hot leg” of the primary coolant circuit) to the inside of the containment shell 54. When initially commencing the pressurization, the coolant circuit 46 and the containment structure 54 are coupled by the depressurization valve 72 through one or more small conduits 76 along a flow path with not insubstantial back pressure. As the pressure in the coolant circuit drops, additional conduits are opened by further depressurization valves 72 in stages, each stage opening a larger and/or more direct flow path between the coolant circuit 46 and the containment shell 54. The initial depressurization stages couple a pressurizer tank 80 which is connected by conduits to the coolant circuit hot leg 56, to spargers 74 in an in-containment refueling water supply tank 50. The spargers 74 comprise conduits leading to small jet orifices submerged in the tank, thus providing back pressure and allowing water to condense from steam emitted by the spargers into the tank 50. The successive depressurization stages have progressively larger conduit inner diameters. A final stage has a large conduit 84 that couples the hot leg directly into the containment shell 54, for example, at a main coolant loop compartment 40 through which the hot leg 56 of the reactor circuit 46 passes. This arrangement reduces the pressure in the coolant circuit expeditiously, substantially to atmospheric pressure, without sudden hydraulic loading of the respective reactor conduits. When the pressure is sufficiently low, water is added to the coolant circuit by gravity flow from the in-containment refueling water supply tank 50. Automatic depressurization in the AP1000 reactor system is a passive safeguard which ensures that the reactor core is cooled even in the case of a major loss of coolant accident such as a large breach in the reactor coolant circuit. Inasmuch as the in-containment refueling water storage tank drains by gravity, no pumps are required. Draining the water into the bottom of the containment building where the reactor vessel is located, develops a fluid pressure head of water in the containment sufficient to force water into the depressurized coolant circuit without relying on active elements such as pumps. Once the coolant circuit is at atmospheric pressure and the containment is flooded, water continues to be forced into the reactor vessel, where the boiling of the water cools the nuclear fuel. Water in the form of steam escaping from the reactor coolant circuit is condensed on the inside walls of the containment shell, and drained back to be injected again into the reactor coolant circuit. The foregoing arrangement has been shown to be effective in the scenario of a severe loss of coolant accident. However, there is a potential that if the automatic depressurization system is activated in less dire circumstances, the containment may be flooded needlessly. Depressurization followed by flooding of the reactor containment requires shut down of the reactor and a significant cleanup effort. This concern has been partially addressed in U.S. Pat. No. 5,268,943, assigned to the Assignee of this invention. It has been postulated that a spurious actuation of the AP1000 automatic depressurization system under normal conditions could lead to an accident that is more severe than has been analyzed for the plant. Accordingly, a further improvement in the automatic depressurization is desired to guard against such an occurrence. Therefore, it is an object of this invention to provide a device that blocks actuation of the automatic depressurization system valves under normal plant conditions. It is further object of this invention to provide such a device that will maintain a blocking signal on the inputs of the depressurization system when the core makeup tanks are full, to reduce the initiating event frequency of spurious automatic depressurization system actuation. In true accident scenarios, the core makeup tanks are drained in the early stages of the mitigation. Therefore, low level in either of these tanks will provide an indication that the blocking signal needs to be removed to allow the safety system to actuate the automatic depressurization system valves as designed. Further, it is an object of this invention to provide such a system that is substantially fail safe to assure that it does not impede the actuation of the automatic depressurization system when it is needed. To achieve the foregoing objectives, this invention provides a nuclear reactor system having a pressurized coolant circuit including a pressure vessel, heat exchanger, core makeup tank and connecting piping, with the connecting piping including a main coolant loop piping connecting the heat exchanger to the pressure vessel in a closed loop configuration and a makeup water connection connecting the core makeup tank to the pressure vessel. The nuclear reactor system is housed within a containment shell that also has an in-containment water reservoir that is maintained vented to an atmosphere of the containment shell. The nuclear reactor system further includes a depressurization system for automatically depressurizing the pressurized coolant circuit in the event of a design basis accident and connecting the water reservoir to the pressure vessel. A blocking device is connected to the depressurization system for preventing the depressurization system from activating when coolant within the core makeup tank is above a preselected level. Preferably, the blocking device fails in a failsafe condition wherein the failure of substantially any component within the blocking device will stop the blocking device from preventing the depressurization system from activating. Desirably, the preselected level is a level at which the core makeup tank is considered substantially full. In one embodiment, the core makeup tank includes more than one water tank connected to the pressure vessel and wherein the blocking device prevents the depressurization system from activating when coolant in each of the water tanks is above the preselected level. Preferably, the blocking device does not prevent the depressurization system from activating when coolant within any of the water tanks is below the preselected level. From FIG. 2, it can be appreciated that there are two sources of coolant to make up for loss of the coolant in the AP1000 nuclear reactor system 22. An inlet 32 of the high pressure core makeup tank 33 is coupled by valves 35 to the reactor coolant inlet or “cold leg” 36. The high pressure core makeup tank 33 is also coupled by motorized valves 38 and check valves 42 to a reactor vessel injection inlet 44. The high pressure core makeup tank 33 is operable to supply additional coolant to the reactor coolant circuit 46, at the operational pressure of the reactor, to make up for relatively small losses. However, the high pressure core makeup tank 33 contains only a limited supply of coolant, though, as can be appreciated from FIG. 1, there are two core makeup tanks in the system. A much larger quantity of coolant water is available from the in-containment refueling water storage tank 50, at atmospheric pressure due to vent 52, which opens from the tank 50 into the interior of the containment building 54. When the reactor system 22 is operating, the coolant circuit operational pressure is on the order 2,250 psi (150 bar). Therefore, in order to add coolant to the reactor vessel 60 and the coolant circuit 46 coupled thereto, the system must be depressurized, i.e., brought down to atmospheric or nearly atmospheric pressure in the containment. The automatic depressurization system depressurizes the coolant circuit 46 in stages, to limit the thermal and hydraulic loading on the main coolant pipes 36, 56 and the reactor vessel, due to depressurization, by venting into the containment 54. The nuclear reactor system 22 in the example shown in FIGS. 1 and 2, is depressurized by venting the cooling circuit 46 into the containment 54 in four stages of decreasing pressure, the last stage characterized by direct coupling of the cooling circuit 46 to the interior of the environment of the containment 54. In the last stage, coolant from the refueling water storage tank 50 can be fed by gravity through motorized valve 62 and check valve 64 into the reactor vessel injection inlet 44. Additionally, in the last stage, the containment building 54 can be flooded with water from the refueling water storage tank 50. Water in the containment 54 thus drains by gravity into the coolant circuit 46 and is boiled by the nuclear fuel. Steam thereby generated is vented into the containment 54, where the steam condenses on the relatively cooler containment walls as explained in co-pending application Ser. No. 13,444,932, filed Apr. 12, 2012. The condensed water drains back into the bottom of the containment 54, and is recycled; the system thus described providing a passive cooling means independent of pumps and other actively powered circulation components. During the staged depressurization represented by the schematic shown in FIG. 2, three initial stages are achieved successively by opening the initial stage depressurization valves 72 coupled via spargers 74 between the cooling circuit 46 and the containment shell 54. The respective valves 72 in each depressurization leg 76 are opened at successively lower pressures and preferably are coupled between the coolant system pressurizer 80 and the spargers 74 submerged in the refueling water supply tank 50 in parallel legs along conduits 76. The successively opened conduits 76 are progressively larger for the successive stages, thus venting the coolant circuit 46 more and more completely to the containment 54. The final stage of depressurization, achieved by opening valve means 82, uses the largest conduit 84 and directly couples the coolant circuit 46 to the containment shell 54 (rather than through the spargers 74 in the refueling water supply tank 50), for example, opening into a loop compartment 40 in the containment 54, containing the reactor outlet conduit 56 which leads to a steam generator 30 shown in FIG. 1. The coolant circuit 46 of the reactor having such a passive safeguard system, including a staged depressurization system, is generally coupled to a residual heat removal system 90, whereby makeup water can be supplied to the coolant circuit 46 before depressurization reaches the final stage. The residual heat removal system 90 normally is activated only during shutdown, for removing normal decay heat from the reactor core. Whereas the residual heat removal system is manually activated, it is not intended as a safety grade apparatus for cooling in the event of an accident. However, by arranging a coupling between the residual heat removal system 90 and the reactor coolant circuit 46, it is possible to use the residual heat removal pumps for moving coolant from the refueling water supply 50 into the cooling circuit 46 before depressurization reaches the last stage or for cooling the water in the refueling water supply 50. Referring to FIG. 2, a nuclear reactor having a reactor vessel 60 disposed in a containment shell 54, has a normally pressurized cooling circuit 46 including the reactor vessel 60. A refueling water storage tank 50 at atmospheric pressure is coupled to a coolant addition system 92 operable to depressurize the coolant circuit 46 for adding coolant from the refueling water storage tank 50 to the coolant circuit 46 at reduced pressure. A residual heat removal loop 94 having at least one pump 96 and at least one heat exchanger 98, with the residual heat removal loop 94 having an inlet 102 and an outlet 104, is coupled to the cooling circuit 46 by manually operable valves 106, 108 shown in FIGS. 2 and 3. Suitable check valves 109 are provided in series at the outlet 104 of the residual heat removal loop 94. One proposed system for the residual heat removal system is shown in FIG. 3 and includes two residual heat removal legs 94 having respective pumps 96 and heat exchangers 98. When the residual heat removal pumps 96 are coupled by the valves 106, 108 between the refueling water supply 50 and the coolant circuit 46, i.e., during depressurization of the coolant circuit prior to reaching the final stage of depressurization, the pumps 96 inject water from the refueling water supply 50 into the direct vessel injection line 112 so that injection can occur when the reactor coolant circuit pressurization drops to below the shutoff head of the pumps 96. Inlet isolation valve 110, and outlet stop-check isolation valves 111 separate the two parallel coupled residual heat removal legs 94. The pump 96 can be protected from overpressure problems by including bypass paths 113, having restricted orifices 114 for bleeding off pressure in the event the pumps are activated when the outlet valve 108 is closed or when the pumps 96 cannot exceed the pressure head of the line leading to the reactor injection inlet 44. Referring to FIG. 2, the stages of depressurization can be triggered based on the level of coolant in the coolant makeup tank 33. For example, the level of coolant can be determined using sensors 122 disposed at different levels on tank 33, coupled to the reactor control system (not shown) for opening the staged depression valves 92 upon reaching a corresponding coolant level. The pumps 96 discharge into the coolant circuit 46 at a point downstream of the coolant makeup tank 33. Therefore, operation of the pumps 96 can effectively shut off flow from the coolant makeup tank 33. The fluid pressure head loss HF due to friction between the direct vessel injection port 132 and the connection 134 of the residual heat removal system discharge line 104 is set, by appropriate adjustment of the dimensions of the orifice 133, to be equal to the elevation head difference (HELEV) from connection 134 to the water level 136 in the core makeup tank 33. Therefore, if the head loss HF from point 132 to point 134 corresponds to the fluid pressure head due to a coolant elevation in the core makeup tank 33 above the coolant elevation at which the final stage depressurization valve 84 opens, then the final stage depressurization valves 82 will not be open during injection of coolant from the residual water supply 50 by the residual heat removal pumps 96. Activation of the residual heat removal system 90 during depressurization thus prevents the automatic depressurization system from advancing to the stage at which the containment is flooded by way of the conduit 84. Inasmuch as the coolant circuit 46 is pressurized during operation of the reactor, the stages of depressurization involve a loss of coolant from the reactor coolant circuit 46 at varying rates. The venting of steam and water removes coolant from the circuit 46 and moves the coolant into the refueling water supply tank 50 through the spargers 74, or into the containment structure 54 directly via final stage conduit 84. Accordingly, the level of coolant in the core makeup tank 33 falls during operation of the depressurization system. The falling level of the makeup supply triggers the next stage of depressurization, proceeding through each of the stages following initiation of automatic depressurization. The residual heat removal system 90 precludes unnecessary flooding of the containment 54, for example, when the automatic depressurization system is activated inadvertently, or when loss of coolant triggering the initial stage of depressurization is not of a critical nature. If a critical loss of coolant accident occurs, the residual heat removal system 90 still can be activated manually, without adverse effects. Whether or not the operators activate the residual heat removal pumps 96, if the level in the core makeup tank 33 drops to the level at which final stage depressurization is triggered (e.g., at 25% of the volume of the core makeup tank), the coolant circuit 46 is vented to the containment 54, and coolant flows by gravity from the refueling water supply 50 to the coolant circuit 46 and/or to the bottom of the containment 54, effecting passive cooling. The preferred valving arrangement as shown in FIG. 3 includes at least one inlet valve 142 coupled to an inlet 102 of the residual heat removal system 90, selectively coupling the residual heat removal system to one of the coolant circuit 46 and the refueling water storage tank 50 and at least one outlet valve 144 coupled to an outlet 104 of the residual heat removal system 90, selectively coupling the residual heat removal system 90 to either the coolant circuit 46 or the refueling water storage tank 50. This provides the further capability of using the residual heat removal system 90 to cool the refueling water storage tank 50. For this purpose, the inlet 102 and the outlet 104 of the residual heat removal system 90 both are coupled to the refueling water supply tank 50, in a coolant loop apart from the reactor coolant circuit 46. Cooling of the refueling water supply 50 is useful in the event a supplemental heat exchanger 152 is arranged in the refueling water supply tank 50, or if the refueling water supply 50 has become heated by operation of the depressurization system to vent steam and hot water into the refueling water supply. The foregoing discussion in regards to FIGS. 2 and 3 includes only a single core makeup tank and a single direct reactor vessel injection line. In the event the passive cooling system employs more than one high pressure makeup tank and/or direct reactor vessel injection port, as shown in FIG. 1, then it is necessary to couple one or more legs of the residual heat removal system to each of the high pressure tanks and/or direct injection ports, substantially as shown in FIG. 2. For example, in FIG. 3, two direct reactor vessel injection ports 44 are shown coupled to the residual heat removal system. From the foregoing, it should be appreciated that activation of the automatic depressurization system is a major reactor event that, while necessary to deal safely with a postulated accident, can be extremely costly if set off inadvertently. A concern has been raised over the potential for spurious actuation of the automatic depressurization system due to CCF (Common Cause Failure, i.e., multiple failures due to a single cause or event) of the safety system software. The device of this invention blocks spurious actuation of the automatic depressurization system valves. The device of this invention is designed to be highly reliable and failsafe so that the impact on plant safety due to the increased probability of failure on demand of the automatic depressurization system is minimized. Avoiding a spurious actuation of the automatic depressurization system under normal plant operating conditions will avoid the concern that such an unlikely event could lead to an accident that is more severe than has been analyzed for the plant. The device of this invention blocks actuation of the automatic depressurization system valve under normal plant conditions, when the core makeup tanks are full, to reduce the initiating event frequency of spurious automatic depressurization system actuation. In true accident scenarios, the core makeup tanks are drained in the early stages of the mitigation. Low level in either of these tanks is used by this invention to remove the block signal and allow the safety system to actuate the automatic depressurization system valves as designed. The application of the automatic depressurization system blocking device of this invention is shown in FIG. 4. One blocking device is located in each of the safety system divisions (with four divisions provided for redundancy) to block the actuation of the automatic depressurization system valves in that division. The device accepts two voltage inputs representing the level measurements in the core makeup tanks (CMT1Lvl and CMT2Lvl). These voltages are derived from dropping a 4-20 mA current loop 202 signal, which is shared with the analog inputs of the safety system computer, across a precision 50 ohm resistor 200. This resistor is external to the device, located on the terminal blocks, so that the device may be removed without disrupting the current loop 202. The device of this invention provides four photo-transistor outputs (MOSFETs) 204 that are connected to the appropriate Z-Port CLOSE input 206 of the Component Interface Module (“CIM”—described in U.S. Pat. No. 6,842,669) that prioritizes commands going to the valves of the automatic depressurization system. The Z-Port has a higher priority than the normal safety system command, so that commanding a valve to CLOSE through the Z-Port will block any OPEN command from the safety system. The photo-transistors 204 provide galvanic isolation between the blocking device 210 and the CIMs, which may be located in different cabinets. The photo-transistors are described and shown as MOSFETs, though it should be appreciated that other alternatives such as bipolar photo-transistors may also be used. The key requirement of the blocking device 210 is that to the maximum extent practical it should be “failsafe.” This means that the component failures should cause the output photo-transistors 204 to turn OFF, thus removing the block of the automatic depressurization system valves. Also, a manual override 208 is provided to allow the operator to remove the block so that the operator can manually operate the automatic depressurization system valves to mitigate an accident or to perform surveillance testing of the valves. A preferred embodiment of the circuit of the blocking device of this invention is shown in FIG. 5. The circuit operates as an oscillator that runs as long as the voltage of both inputs 212 and 214 is above a threshold value. The gates U1 and U2 are cross connected to form an R-S flip-flop. The output of one of these gates will be high while the other will be low. Starting from an initial assumption that U1 is low and U2 is high, photo-transistors Q1, Q4 and Q6 will be OFF while photo-transistors Q2, Q3 and Q5 will be ON. Q2 being ON will short the feedback capacitor C2 keeping the output of amplifier A2 at zero. Since the output of A2 is less than the zener diode D1 voltage, the output of comparator A4 will be at the maximum value. Q1 is OFF which allows A1 to integrate the input 212. This operational amplifier circuit is a lag function with a time constant of R1×C1 and a gain of R1/R3. The other resistors of this circuit R2 and R4 are of equal values to R3 and R1, respectively, to provide a balanced impedance for the input. When the output voltage of A1 increases to a value greater than the zener diode D1 voltage, the comparator A3 output will go to zero thus turning the output of gate U1 high. This high signal combined with a high output of A4 causes the output of gate U2 to go low. The output of gate U2 is connected as an input to U1 which keeps the output of U1 high. With the states of the two gates now reversed, photo-transistors Q1, Q4 and Q6 will be ON while Q2, Q3 and Q5 will be OFF. Q1 being ON will short the feedback capacitor C1 causing the output of amplifier of A1 to return to zero. Q2 is now OFF which allows amplifier A2 to integrate its input voltage 214. The polarity across the primary winding of transformer T1 is reversed. This process alternates between the two inputs, providing an alternating current wave form at the transformer primary, thus causing power conversion to occur to the secondary of the transformer T1. It should also be appreciated that transistors Q1-Q6 need not be photo-coupled, but could alternatively be direct base connected devices. In the event that either input is less than the threshold set for the zener diode D1 voltage and the R1/R3 (R5/R7) gain, the associated comparator will not switch, the oscillation stops as does the power conversion through the transformer T1. The frequency of the oscillation at normal core makeup tank full conditions is determined by the R1×C1 (R5×C2) time constance. The switching threshold is fixed rather than being adjustable to reduce the chance of drift or the need for a calibration procedure. The set-point to remove the block does not need to be precise as long as it is well away from the full core makeup tank signal and the actuation point where the safety system will legitimately want to open the automatic depressurization system valves. Resistors R10 and R11 limit the emitter currents through the two chains of photo-transistors Q1, Q4, Q6 and Q2, Q3, Q5. By connecting these emitter LEDs in series, the output drive power from the logic gates U1 and U2 is minimized. During the polarity switching of the transformer primary, there will be a brief period of a direct short of the power source to ground, for instance, through Q3 and Q6 when they are simultaneously ON. The current through this short is limited by R12 to prevent damage to the transistors. The energy for this short current will temporarily be supplied from the power supply through the capacitor C5. Resistors R13 and R14, and capacitor C3 provide a low pass filter across the transformer primary winding to make the input waveform more sinusoidal to improve the power conversion. Diodes D2, D3, D4 and D5 form a full wave rectifier on the transformer secondary circuit to convert the AC back to a DC voltage. The power requirement through the transformer is not high. It only needs to drive the emitter LEDs of the output photo-transistors 204. R16 and C4 form a ripple filter to remove the remaining AC component of the transformer output following the full wave rectification. The time response requirement of the blocking device is not particularly fast, so this filter can have a relatively long time constant. Another alternative is to feedback the transformer T1 secondary voltage, through an appropriately sized resistor and after rectification and filtering (i.e. the voltage on capacitor C4), to the summing junction of comparators A3 and A4. This feedback will cause a small shift to occur in the comparator switching threshold when the oscillation stops, thereby adding hysteresis to the preselected level action point of the blocking device. This hysteresis prevents “chattering” that could occur if the process input (CMT level) hovers near the threshold value. The current in the emitter LEDs of the output photo-transistor chain 204, i.e., Q7 through Q10 is limited by R15. In addition, a zener diode D6 is included in the emitter circuit so that the output voltage of the transformer must exceed a predetermined value to turn the output transistor ON. The value of the zener diode is selected so that under normal operating conditions, with both inputs 212 and 214 above the threshold and full voltage being sent through the transformer, the outputs will be ON. However, in the event that a failure of one of the transformer primary transistor switches cause the primary voltage to drop to half the normal value, the secondary voltage will drop below the zener diode voltage and the outputs will turn OFF. LED D7 provides a local indication of the blocker state. This can be used in a manual operability check. Each of the inputs is provided with disconnect/test injection links 216. A quick check can be performed simply by opening a link and observing that the outputs turn OFF. A more protracted test would inject a voltage input into the terminals to determine the threshold at which the oscillation stops. Power is provided to the blocking device from dual 24 volt DC supplies 218 through auctioneering diodes D8 and D9. This power source is fused, F1, so that a fault in the device, such as a short of the transformer primary transistors, will blow the fuse to prevent propagation to other cabinet devices. This power source is switched by an external, normally closed, contact. This power switch implements the requirement for manual override. The switch may actually be a series connection of switches in the main control room (×2) and at the remote control transfer station (×2), to provide single failure tolerance and multiple control point for the operator override of the block. The voltage level from the dual 24 volt supply 218 is not critical. Alternatively, 48 volt DC supplies may be used to improve the switching characteristics of the series string of manual override switches. In addition to the manual override, other interlocking signals may be included in the series connection of switches. For example, the contact of an under-voltage relay connected to the AC power supply of the safety system can be used to remove the block when the system power is being provided from the back-up batteries following a loss of off-site power sources. A 15 volt DC voltage regulator 220 provides the Vcc to the device gates and amplifiers. Local power indication is provided by LED D8 with its current being limited by R17. Surge protection is provided on the two sensor inputs and on the manual override switch by MOVs RV1-RV9. Surge protection is not needed on the outputs since these will be connected to the CIMs in the same cabinet or in a nearby cabinet. As previously mentioned, high reliability is a key requirement of the automatic depressurization system blocking device because it has the potential to defeat valid actuation of the automatic depressurization system valves. The means used to achieve this high reliability is the “failsafe” design principle. Under this principle, the majority of component failures should either cause the block to be removed, or to not prevent the removal of the block under the condition where one of the two inputs is less than the threshold value. Table 1 is an FMECA (“Failure Mode, Effects, and Criticality Analysis”) of the schematic shown in FIG. 5. For each component in the circuit, the possible failure modes are identified, and the effects (consequences) of those failure modes are stated. The effects are assigned to one of four categories defined as follows: S1-failsafe; the failure effect removes the ADS block by deenergizing the output transistors; S2-failure safe; the failure effect does not prevent the deenergizing of the output transistors by one of the inputs being below the threshold; S3-failsafe; the failure effect prevents output turnoff by one input but does not prevent the other input from being effective; and D-dangerous failure; one or more of the output transistors will not turn off when the input is below the threshold value. In addition to categorizing the failure effects, the “detectability” of the failure is identified with a D or U (for Detectable or Undetectable, respectively). This device does not have a continuous diagnostic capability. Instead, a simple check can be made by manually opening each of the inputs in turn and verifying that the automatic depressurization signal block signals at the CIM Z-Ports are removed. The CIM Z-Ports are monitored by the plant computer system. If any of the blocks are removed under normal operating conditions without the check being done, this would also indicate a block device failure. The check would also include a test of the manual override by operating the switch in the control room. Any failures not reviewed by this simple check are identified as Undetectable. Such failures would be revealed by a comprehensive bench test of the device that measures waveforms and specific component failures done during plant shutdown. Failure rates for each component are included in Table 1 based on the component failure rate models found in the reliability information and analysis (RIAC) tool 217Plus. These are expressed in the units Failures In Time (FIT) which are failures per 109 hours of calendar time. The relative likelihood of the various failure modes is shown in the Alpha column, and is taken from the RIAC publication, CRTA-FMECA. The product of the FIT and Alpha columns produces the failure rate of the specific failure mode. Table 2 is a summary of the failsafe modes of the device. 87.7 percent of all failures result in one of the three safe conditions identified. The dangerous failure modes are: 1) short or low off resistance of one of the output FETs; 2) short of the surge suppressor across the manual override switch; and 3) change in the zener voltage of threshold reference D1. The first two of these would be detected by the simple check described previously. If this check is performed quarterly, then the probability of dangerous failure on demand of the blocking device is extremely low when coupled with the low frequency of spurious actuation due to safety system software failure, and should be sufficient to put this accident scenario outside of design basis consideration. TABLE 1ADS Blocking Device FMECAFAILUREREFMODEEFFECTSAFEDETALPHAFITPRODA1OutputU1 stays high; Q4 and Q6 stayS1D0.453.91.755Stuck HighON; power supply is shortedthrough R12 when Q3 and Q5turn ON; fuse blowsA1OutputU1 stays low; oscillationS1D0.453.91.755Stuck Lowstops; T1 voltage drops; outputFETs turn OFFA1UnstableOscillation frequency aboveS1D0.103.9.039OscillationT1 primary filter; T1 voltagedrops; output FETs turn OFFA2OutputU2 stays high; Q3 and Q5 stayS1D0.453.91.755Stuck highON; power supply is shortedthrough R12 when Q4 and Q6turn ON; fuse blowsA2OutputU2 stays low; oscillationS1D0.453.91.755Stuck Lowstops; T1 voltage drops; outputFETs turn OFFA2UnstableOscillation frequency aboveS1D0.103.9.039OscillationT1 primary filter; T1 voltagedrops; output FETs turn OFFA3OutputU1 stays low; oscillationS1D0.503.91.95Stuck Highstops; T1 voltage drops; outputFETs turn OFFA3OutputU1 stays high; Q4 and Q6 stayS1D0.503.91.95Stuck LowON; power supply is shortedthrough R12 when Q3 and Q5turn ON; fuse blowsA4OutputU2 stays low; oscillationS1D0.503.91.95Stuck Highstops; T1 voltage drops; outputFETs turn OFFA4OutputU2 stays high; Q3 and Q5 stayS1D0.503.91.95Stuck LowON; power supply is shortedthrough R12 when Q4 and Q6turn ON; fuse blowsC1ShortA1 stays low; oscillationS1D0.494.82.352stops; T1 voltage drops; outputFETs turn OFFC1Change inShift in oscillation frequency;S2U0.294.81.392Valuesmall change does not affectoperationC1OpenA1 goes high as soon as Q1 isS1D0.224.81.056OFF; duty cycle has largechange; T1 voltage drops;output FETs turn OFFC2ShortA2 stays low; oscillation stops;S1D0.494.82.352T1 voltage drops; output FETsturn OFFC2Change inShift in oscillation frequency;S2U0.294.81.392Valuesmall change does not affectoperationC2OpenA2 goes high as soon as Q1 isS1D0.224.81.056OFF; duty cycle has largechange; T1 voltage drops;output FETs turn OFFC3ShortT1 primary shorted; T1 outputS1D0.494.82.352voltage drops; output FETs turnOFFC3Change inMore harmonics in T1 voltage;S2U0.294.81.392Valuesmall change does not affectoperationC3OpenT1 input is square wave;S1D0.224.81.056secondary voltage is highlypeaked wave form; RMSvoltage drops; output FETs turnOFFC4ShortOutput drive voltage shorted;S1D0.690.830.5727output FETs turn OFFC4OpenHigh ripple on FET driveS2D0.170.830.1411voltage; intermittent turningOFF of blocks noticed by CIMmonitorC4Change inIncrease in voltage ripple; smallS2U0.140.830.1162Valuechange does not affectoperationC5ShortPower supply to device dropsS1D0.690.830.5727to zero; fuse blowsC5OpenSwitching transients mayS2U0.170.830.1411disrupt oscillation; does notprevent turn-off when inputsare lowC5Change inIncrease in voltage ripple; smallS2U0.140.830.1162Valuechange does not affectoperationD1ParameterInput amps cannot achieveS1D0.353.41.19Changethreshold; oscillation stops;voltageoutput FETs are turned OFFincreaseD1ParameterChange in switching thresholdDU0.353.41.19Changemay cause block to not bevoltageremoved in timedecreaseD1OpenInput amps cannot achieveS1D0.173.40.578threshold; oscillation stops;output FETs are turned OFFD1ShortThreshold exceeded early inS1D0.133.40.442each cycle; oscillationfrequency increasessignificantly above T1 filter;T1 voltage drops; output FETsturn OFFD2ShortT1 secondary shorted for halfS1D0.511.30.663cycle; RMS voltage drops;output FETs turn OFFD2OpenIncreased ripple; decreasedS1D0.291.30.377RMS voltage; D6 blocks outputFETs from turning OND2ParameterDesign not sensitive toS2U0.201.30.26Changecomponent parametersD3ShortT1 secondary shorted for halfS1D0.511.30.663cycle; RMS voltage drops;output FETs turn OFFD3OpenIncreased ripple; decreasedS1D0.291.30.377RMS voltage; D6 blocks outputFETs from turning OND3ParameterDesign not sensitive toS2U0.201.30.26Changecomponent parametersD4ShortT1 secondary shorted for halfS1D0.511.30.663cycle; RMS voltage drops;output FETs turn OFFD4OpenIncreased ripple; decreasedS1D0.291.30.377RMS voltage; D6 blocks outputFETs from turning OND4ParameterDesign not sensitive toS2U0.201.30.26Changecomponent parametersD5ShortT1 secondary shorted for halfS1D0.511.30.663cycle; RMS voltage drops;output FETs turn OFFD5OpenIncreased ripple; decreasedS1D0.291.30.377RMS voltage; D6 blocks outputFETs from turning OND5ParameterDesign not sensitive toS2U0.201.30.26Changecomponent parametersD6ParameterFault tolerance to voltageS2U0.693.42.346Changereducing failures is reduced bynormal operation is not affectedD6OpenEmitter circuit of output FETsS1D0.183.40.612is open; output FETs are turnedOFFD6ShortHigh current through FETS1D0.133.40.442emitters causes consequentialfailures; one or more FETs turnOFFD7OpenEmitter circuit of outputS1D0.700.130.019FETs is open; output FETsare turned OFFD7ShortLocal indication of blockS2D0.300.130.039inoperative; does not affectoperationD8OpenLocal indication of power isS2D0.700.130.091inoperative; does not affectoperationD8ShortPower supply is shorted; fuseS1D0.300.130.039blowsD9ShortFault tolerance for powerS2U0.511.30.663supplies reduced; does notaffect device operationD9OpenFault tolerance for powerS2U0.291.30.377supplies reduced; does notaffect device operationD9ParameterDesign not sensitive toS2U0.201.30.26Changecomponent parametersD10ShortFault tolerance for powerS2U0.511.30.663supplies reduced; does notaffect device operationD10OpenFault tolerance for powerS2U0.291.30.377supplies reduced; does notaffect device operationD10ParameterDesign not sensitive toS2U0.201.30.26Changecomponent parametersF1Fails to OpenFault on device couldS2U0.494924.01propagate to protectiondevices of power supplies;may not clearF1Slow to OpenFault on device couldS2U0.434921.07propagate to protectiondevices of power supplies;may not clearF1PrematurePower to device is removed;S1D0.08493.92Openoutput FETs turn OFFQ1ShortA1 stays low; oscillationS1D0.51157.65stops; T1 voltage drops;output FETs turn OFFQ1Output LowA1 gain is reduced; full inputS1D0.22153.3Res whendoes not reach switchingOFFthreshold; oscillation stopsQ1ParameterDesign not sensitive toS2U0.17152.55Changecomponent parametersQ1OpenC1 does not discharge; A1S1D0.05150.75remains high; power supplyis shorted through R12 whenQ3 and Q5 turn on; fuseblowsQ1OutputC1 does not fully discharge;S1D0.05150.75High Resoscillation frequency willwhen ONincrease and duty cycle shift;T1 voltage drops; D6 preventsoutput FET turn-onQ2ShortA2 stays low; oscillation stops;S1D0.51157.65T1 voltage drops; output FETsturn OFFQ2OutputA2 gain is reduced; full inputS1D0.22153.3Low Resdoes not reach switchingwhen OFFthreshold; oscillation stopsQ2ParameterDesign not sensitive toS2U0.17152.55Changecomponent parametersQ2OpenC2 does not discharge; A2S1D0.05150.75remains high; power supply isshorted through R12 when Q4and Q6 turn on; fuse blowsQ2OutputC2 does not fully discharge;S1D0.05150.75High Resoscillation frequency willwhen ONincrease and duty cycle shift;T1 voltage drops; D6 preventsoutput FET turn-onQ3ShortPower supply is shortedS1D0.51157.65through R12 when Q6 turnsON; fuse blowsQ3OutputT1 voltage drops; D6 blocksS1D0.22153.3Low Resoutput FETs from turning onwhen OFFQ3ParameterDesign not sensitive toS2U0.17152.55Changecomponent parametersQ3OpenT1 voltage drops; D6 blocksS1D0.05150.75output FETs from turning onQ3OutputT1 voltage drops; D6 blocksS1D0.05150.75High Resoutput FETs from turning onwhen ONQ4ShortPower supply is shortedS1D0.51157.65through R12 when Q5 turnsON; fuse blowsQ4OutputT1 voltage drops; D6 blocksS1D0.22153.3Low Resoutput FETs from turning onwhen OFFQ4ParameterDesign not sensitive toS2U0.17152.55Changecomponent parametersQ4OpenT1 voltage drops; D6 blocksS1D0.05150.75output FETs from turning onD8OpenLocal indication of power isS2D0.700.130.091inoperative; does not affectoperationD8ShortPower supply is shorted; fuseS1D0.300.130.039blowsD9ShortFault tolerance for powerS2U0.511.30.663supplies reduced; does notaffect device operationD9OpenFault tolerance for powerS2U0.291.30.377supplies reduced; does notaffect device operationQ4OutputT1 voltage drops; D6 blocksS1D0.05150.75High Resoutput FETs from turning onwhen ONQ5ShortPower supply is shortedS1D0.51157.65through R12 when Q4 turnsON; fuse blowsQ5OutputT1 voltage drops; D6 blocksS1D0.22153.3Low Resoutput FETs from turning onwhen OFFQ5ParameterDesign not sensitive toS2U0.17152.55Changecomponent parametersQ5OpenT1 voltage drops; D6 blocksS1D0.05150.75output FETs from turning onQ5OutputT1 voltage drops; D6 blocksS1D0.05150.75High Resoutput FETs from turning onwhen ONQ6ShortPower supply is shortedS1D0.51157.65through R12 when Q3 turnsON; fuse blowsQ6OutputT1 voltage drops; D6 blocksS1D0.22153.3Low Resoutput FETs from turning onwhen OFFQ6ParameterDesign not sensitive toS2U0.17152.55Changecomponent parametersQ6OpenT1 voltage drops; D6 blocksS1D0.05150.75output FETs from turning onQ6OutputT1 voltage drops; D6 blocksS1D0.05150.75High Resoutput FETs from turning onwhen ONQ7ShortCIM Z-Port stuck ONDD0.51157.65Q7OutputCIM Z-Port may be ON whenDD0.22153.3Low Resblock is removedwhen OFFQ7ParameterDesign not sensitive toS2U0.17152.55Changecomponent parametersQ7OpenCIM Z-port stuck OFF; blockS1D0.05150.75removed for affectedcomponentQ7OutputCIM Z-port may be OFF; blockS1D0.05150.75High Resmay be removed for affectedwhen ONcomponentQ8ShortCIM Z-Port stuck ONDD0.51157.65Q8OutputCIM Z-Port may be ON whenDD0.22153.3Low Resblock is removedwhen OFFQ8ParameterDesign not sensitive toS2U0.17152.55Changecomponent parametersQ8OpenCIM Z-port stuck OFF; blockS1D0.05150.75removed for affectedcomponentQ8OutputCIM Z-port may be OFF; blockS1D0.05150.75High Resmay be removed for affectedwhen ONcomponentQ9ShortCIM Z-Port stuck ONDD0.51157.65Q9OutputCIM Z-Port may be ON whenDD0.22153.3Low Resblock is removedwhen OFFQ9ParameterDesign not sensitive toS2U0.17152.55Changecomponent parametersQ9OpenCIM Z-port stuck OFF; blockS1D0.05150.75removed for affectedcomponentQ9OutputCIM Z-port may be OFF; blockS1D0.05150.75High Resmay be removed for affectedwhen ONcomponentQ10ShortCIM Z-Port stuck ONDD0.51157.65Q10OutputCIM Z-Port may be ON whenDD0.22153.3Low Resblock is removedwhen OFFQ10ParameterDesign not sensitive toS2U0.17152.55Changecomponent parametersQ10OpenCIM Z-port stuck OFF; blockS1D0.05150.75removed for affectedcomponentQ10OutputCIM Z-port may be OFF; blockS1D0.05150.75High Resmay be removed for affectedwhen ONcomponentR1OpenA1 integrates to Vcc; exceedsS3U0.591.60.944threshold even at low inputR1ParameterA1 gain is changed; may notS3U0.361.60.576Changeswitch at thresholdR1ShortA1 stays low; oscillationS1D0.051.60.08stops; T1 voltage drops;output FETs turn OFFR2OpenA1 stays low; oscillationS1D0.591.60.944stops; T1 voltage drops;output FETs turn OFFR2ParameterA1 gain is changed; may notS3U0.361.60.576Changeswitch at thresholdR2ShortA1 gain is changed; may notS3U0.051.60.08switch at thresholdR3OpenA1 stays low; oscillationS1D0.591.60.944stops; T1 voltage drops;output FETs turn OFFR3ParameterA1 gain is changed; may notS3U0.361.60.576Changeswitch at thresholdR3ShortA1 gain is changed; may notS3U0.051.60.08switch at thresholdR4OpenCommon mode noise rejectionS2U0.591.60.944capability is reduced but doesnot affect operationR4ParameterA1 gain is changed; may notS3U0.361.60.576Changeswitch at thresholdR4ShortA1 gain is changed; may notS3U0.051.60.08switch at thresholdR5OpenA2 integrates to Vcc; exceedsS3U0.591.60.944threshold even at low inputR5ParameterA2 gain is changed; may notS3U0.361.60.576Changeswitch at thresholdR5ShortA2 stays low; oscillationS1D0.051.60.08stops; T1 voltage drops;output FETs turn OFFR6OpenA2 stays low; oscillationS1D0.591.60.944stops; T1 voltage drops;output FETs turn OFFR6ParameterA2 gain is changed; may notS3U0.361.60.576Changeswitch at thresholdR6ShortA2 gain is changed; may notS3U0.051.60.08switch at thresholdR7OpenA2 stays low; oscillationS1D0.591.60.944stops; T1 voltage drops;output FETs turn OFFR7ParameterA2 gain is changed; may notS3U0.361.60.576Changeswitch at thresholdR8OpenCommon mode noise rejectionS2U0.591.60.944capability is reduced but doesnot affect operationR8ParameterA2 gain is changed; may notS3U0.361.60.576Changeswitch at thresholdR8ShortA2 gain is changed; may notS3U0.051.60.08switch at thresholdR9OpenReference voltage for thresholdS1D0.591.60.944drops to zero; switching occursrapidly; T1 primary filterreduces voltage to transformer;D6 blocks output FETs fromturning ONR9ParameterDesign not sensitive toS2U0.361.60.576Changecomponent parametersR9ShortExcessive current through D1S1D0.051.60.08causes failure of this diode;threshold increases to Vcc;switching stopsR10OpenQ1, Q4 and Q6 do not turn ON;S1D0.591.60.944oscillation stopsR10ParameterDesign not sensitive toS2U0.361.60.576Changecomponent parametersR10ShortExcessive current through Q1,S1D0.051.60.08Q3 and Q5 emitters causesfailure of one or more of thesedevicesR11OpenQ2, Q3 and Q5 do not turn ON;S1D0.591.60.944oscillation stopsR11ParameterDesign not sensitive toS2U0.361.60.576Changecomponent parametersR11ShortExcessive current through Q2,S1D0.051.60.08Q4 and Q6 emitters causesfailure of one or more of thesedevicesR12OpenLoss of primary voltage to T1;S1D0.591.60.944output FETs turn OFFR12ParameterDesign not sensitive toS2U0.361.60.576Changecomponent parametersR12ShortSwitching transients mayS2U0.051.60.08disrupt oscillation; does notprevent turn-off when inputsare lowR12OpenLoss of primary voltage to T1;S1D0.591.60.944output FETs turn OFFR12ParameterDesign not sensitive toS2U0.361.60.576Changecomponent parametersR12ShortChange in filter cutoffS2U0.051.60.08frequency; may reducetolerance of other faults butdoes not prevent normaloperationR14OpenLoss of primary voltage to T1;S1D0.591.60.944output FETs turn OFFR14ParameterDesign not sensitive toS2U0.361.60.576Changecomponent parametersR14ShortChange in filter cutoffS2U0.051.60.08frequency; may reducetolerance of other faults butdoes not prevent normaloperationR15OpenEmitter circuit of output FETsS1D0.591.60.944is open; output FETs are turnedOFFR15ParameterDesign not sensitive toS2U0.361.60.576Changecomponent parametersR15ShortHigh current through FETS1D0.051.60.08emitters causes consequentialfailures; one or more FETs turnOFFR16OpenEmitter circuit of output FETsS1D0.591.60.944is open; output FETs are turnedOFFR16ParameterDesign not sensitive toS2U0.361.60.576Changecomponent parametersR16ShortHigh ripple on FET driveS2D0.051.60.08voltage; intermittent turningOFF of blocks noticed by CIMmonitorR17OpenLocal indication of power isS2D0.591.60.944inoperative; does not affectoperationR17ParameterDesign not sensitive toS2U0.361.60.576Changecomponent parametersR17ShortPower supply is shorted; fuseS1D0.051.60.08blowsRV1OpenSurge withstand capabilityS2U0.453.41.53reduced but normal operation isnot affectedRV1ParameterDesign not sensitive toS2U0.353.41.19Changecomponent parametersRV1ShortA1 stays low; oscillation stops;S1D0.203.40.68T1 voltage drops; output FETsturn OFFRV2OpenSurge withstand capabilityS2U0.453.41.53reduced but normal operation isnot affectedRV2ParameterDesign not sensitive toS2U0.353.41.19Changecomponent parametersRV2ShortSurge withstand capabilityS2U0.203.40.68reduced but normal operation isnot affectedRV3OpenSurge withstand capabilityS2U0.453.41.53reduced but normal operation isnot affectedRV3ParameterDesign not sensitive toS2U0.353.41.19Changecomponent parametersRV3ShortSurge withstand capabilityS2U0.203.40.68reduced but normal operation isnot affectedRV4OpenSurge withstand capabilityS2U0.453.41.53reduced but normal operation isnot affectedRV4ParameterDesign not sensitive toS2U0.353.41.19Changecomponent parametersRV4ShortA2 stays low; oscillation stops;S1D0.203.40.68T1 voltage drops; output FETsturn OFFRV5OpenSurge withstand capabilityS2U0.453.41.53reduced but normal operation isnot affectedRV5ParameterDesign not sensitive toS2U0.353.41.19Changecomponent parametersRV5ShortSurge withstand capabilityS2U0.203.40.68reduced but normal operation isnot affectedRV6OpenOpen Surge withstandS2U0.453.41.53capability reduced but normaloperation is not affectedRV6ParameterDesign not sensitive toS2U0.353.41.19Changecomponent parametersRV6ShortSurge withstand capabilityS2U0.203.40.68reduced but normal operation isnot affectedRV7OpenSurge withstand capabilityS2U0.453.41.53reduced but normal operation isnot affectedRV7ParameterDesign not sensitive toS2U0.353.41.19Changecomponent parametersRV7ShortManual override of block isDD0.203.40.68inoperativeRV8OpenSurge withstand capabilityS2U0.453.41.53reduced but normal operation isnot affectedRV8ParameterDesign not sensitive toS2U0.353.41.19Changecomponent parametersRV8ShortSurge withstand capabilityS2U0.203.40.68reduced but normal operation isnot affectedRV9OpenSurge withstand capabilityS2U0.453.41.53reduced but normal operation isnot affectedRV9ParameterDesign not sensitive toS2U0.353.41.19Changecomponent parametersRV9ShortSurge withstand capabilityS2U0.203.40.68reduced but normal operation isnot affectedT1OpenSecondary voltage becomeS1D0.426326.46zero; output FETs turn OFFT1ShortSecondary voltage becomeS1D0.426326.46zero; output FETs turn OFFT1ParameterDesign not sensitive toS2U0.166310.08Changecomponent parametersU1InputU1 stays low; oscillation stops;S1D0.181.10.198Open fromT1 voltage drops; output FETsA3turn OFFU1InputU1 goes OFF immediately afterS1D0.181.10.198Open fromturning ON; duty cycle hasU2large change; T1 voltage drops;output FETs turn OFFU1OutputNo drive current for Q1, Q4S1D0.361.10.396Openand Q6; T1 voltage drops;oscillation stopsU1SupplyNo drive current for Q1, Q4S1D0.121.10.132Openand Q6; T1 voltage drops;oscillation stopsU1OutputOscillation stops; T1 voltageS1D0.081.10.088Stuck Lowdrops; output FETs turn OFFU1OutputQ4 and Q6 stay ON; powerS1D0.081.10.088Stucksupply is shorted through R12Highand Q3 and Q5 turn ON; fuseblowsU2InputU2 stays low; oscillation stops;S1D0.181.10.198Open fromT1 voltage drops; output FETsA4turn OFFU2InputU2 goes OFF immediately afterS1D0.181.10.198Open fromturning ON; duty cycle hasU1large change; T1 voltage drops;output FETs turn OFFU2OutputNo drive current for Q2, Q3S1D0.361.10.396Openand Q5; T1 voltage drops;oscillation stopsU2SupplyNo drive current for Q2, Q3S1D0.121.10.132Openand Q5; T1 voltage drops;oscillation stopsU2OutputOscillation stops; T1 voltageS1D0.081.10.088Stuck Lowdrops; output FETs turn OFFU2OutputQ3 and Q5 stay ON; powerS1D0.081.10.088Stucksupply is shorted through R12Highwhen Q4 and Q6 turn ON; fuseblowsVR1No outputLoss of power to device; outputS1D0.523.92.028FETs turn OFFVR1IncorrectNot sensitive to lower voltageS2U0.483.91.872Outputto a point; eventually T1 outputvoltage drops below D6 cutofffor outputs TABLE 2Summary of Fail Safe ModesSAFEDETFITPCTTotal failure rate:372.42Conditional failure rates:= S1189.5350.9%= S2130.2335.0%= S36.9761.9%= D45.6712.3%= D235.3163.2%= U137.1036.8%= D= D44.4811.9% 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 embodiments 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 appended claims and any and all equivalents thereof.
	claims	1. An alignment apparatus for a fuel element in a pressurized-water reactor, comprising:an alignment body having a given overall length in a longitudinal direction, said alignment body having side surfaces formed of side plates and a cross-sectional dimension defined by said side surfaces of said alignment body, said cross-sectional dimension of said alignment body, in a rest position, being smaller by a predetermined nominal value than a corresponding cross-sectional dimension of a reference fuel element, said side surfaces having an overall length in the longitudinal direction being substantially the same as said given overall length of said alignment body in the longitudinal direction, and said side surfaces being constructed for being moveable from the rest position perpendicularly to the longitudinal direction thereby enlarging said cross-sectional dimension of said alignment body for correctively altering the fuel element over its entire length. 2. The alignment apparatus according to claim 1, wherein said predetermined nominal value is 16 mm. 3. The alignment apparatusaccording to claim 1, wherein said moveable side plates have one or a plurality of associated slotted-link guides attaching said side plates via associated displacement bolts to a supporting structure, and wherein said slotted-link guides are shaped to convert a movement of said displacement bolts in the longitudinal direction to a movement of said side plates in a direction perpendicular to the longitudinal direction. 4. The alignment apparatus according to claim 3, wherein said displacement bolts associated with one of said slotted-link guides for said side plates are connected to one another via an attachment apparatus, and said attachment apparatus is disposed to be moved hydraulically or mechanically from the rest position with respect to said side plates in the longitudinal direction of said alignment body. 5. The alignment apparatus according to claim 4, wherein said attachment apparatus is connected to a longitudinally movable head of the alignment apparatus. 6. The alignment apparatusaccording to claim 5, wherein said head is dimensioned in accordance with a fuel element head of the reference fuel element. 7. The alignment apparatus according to claim 1, wherein each of said movable side plates has a fitting and said fitting has a plurality of guide grooves formed therein, said guide grooves extend at right angles to the longitudinal direction of said alignment body, and an associated holding bolt engages into each of said guide grooves and is attached to a supporting frame. 8. The alignment apparatus according to claim 7, wherein said side plates are connected to one another via an attachment apparatus, and said attachment apparatus is mounted to be moved hydraulically or mechanically from the rest position with respect to said side plates in the longitudinal direction of said alignment body. 9. The alignment apparatus according to claim 8, wherein said attachment apparatus is connected to a longitudinally movable head of the alignment apparatus. 10. The alignment apparatus according to claim 9, wherein said head is dimensioned in accordance with a fuel element head of the reference fuel element.
	summary
	summary
	abstract	Radiography backscatter shields and X-ray imaging systems including backscatter shields are disclosed. An example X-ray backscatter shield includes: a conforming backscatter shield configured to provide shielding from Compton scatter radiation when placed in contact with an object to be scanned; and a shield frame configured to couple the backscatter shield to an X-ray source.
051223309	claims	1. An apparatus for monitoring the corrosion of zirconium alloy members in a nuclear reactor core comprising: a sensor means formed from the zirconium alloy and having a first cylindrical section and a reference section, the first cylindrical section having a first sidewall means extending from a base to form an inner first channel, and the reference section being positioned within the channel and attached to the base so that an electric current can be passed throughout the sensor means; sleeve means formed from a stainless steel alloy having a second cylindrical section, to second cylindrical section having a second sidewall means extending from a second base to form a second inner channel; A transition means having coaxial metallurgically bonded third and fourth cylindrical sections so that the third cylindrical section extends from one end and the fourth cylindrical section extends from the other end of the transition means, the third section is formed from the zirconium alloy to mate with the first sidewall means and attached thereto be welding to form a moisture proof seal, the fourth section is formed from the stainless steel alloy to mate with the second sidewall means and attached thereto by welding to form a moisture proof seal; lead means in electrical contact with the sensor means for passing an electric current through out sensor means, the lead means extending through the first and second channels and through a moistureproof seal in the second base; and probe means in electrical contact with the sensor means for measuring potential in the first cylindrical section and the reference section, the probe means extending through the first and second channels and through a moistureproof seal in the second base. a generally cylindrical sensor member formed from the zirconium alloy and comprises of sidewall means extending from a first end to a second end, the sidewall means extending to a first access opening at the first end and to a second access opening at the second end and, the sidewall means having an outer surface, and an interior, and a first annular channel extending in the interior from the first end to the second end, and, the outer surface having at least one scored region; a first generally circular end cap means of the zirconium alloy sealably attached to the first access opening in relationship therewith so that the first cap retains the first annular channel substantially moisture-free, an elongated rod of the zirconium alloy located inside the first annular channel and attached to the first end cap, a generally cylindrical sleeve means formed from stainless steel and comprised of sleeve sidewall means extending from a first sleeve end to a second sleeve end, the sleeve sidewall means extending to a first sleeve access opening at the first sleeve end, to a second sleeve access opening at the second sleeve end, and, the sleeve sidewall means having an interior and a second annular channel extending in the interior from the first sleeve end to the second sleeve end, a transition member having coaxial metallurgically bonded first and second cylindrical sections defining a third annular channel therein, the first cylindrical section extends from one end of the transition member, and the second cylindrical section extends from the other end of the transition member, the first cylindrical section formed from the zirconium alloy to mate with the second end of the sensor member, and the second cylindrical section formed from the stainless steel to mate with the first sleeve end so that the first, second and third annular channels are contiguous and aligned along the same axis, the first cylindrical section being welded to the sensor member and the second cylindrical section being welded to the first sleeve end to form a moistureproof seal for the channels; a first lead in electrical contact with the interior of the sensor member, and a second lead in electrical contact with the rod, the first and second leads insulatively extending from the interior of the sensor member and the rod through the first, second, and third channels, at least two probes in electrical contact with the interior of the sensor member and the rod for detecting electrical potential, the probes insulatively extending from the interior of the sensor member and the rod through the first, second, and third channels, and, a second end cap sealably attached to the second sleeve end of the sleeve so that the first, second and third channels are retained substantially moisture-free, the second end cap means further comprising means defining at least one opening through which the probes and the first and second leads pass in a moisture-proof seal. 2. The apparatus of claim 1 wherein the sensor means has the same crystalline texture as the zirconium alloy member. 3. The apparatus of claim 1 wherein the first cylindrical section has an inner surface facing the inner channel and an oppositely facing outer surface, and the outer surface has a scored section and a smooth section. 4. The apparatus of claim 1 wherein the cylindrical section has an inner surface facing the annular channel and an oppositely facing outer surface, and the cross-section of the cylindrical section is reduced by a circumferential channel on the inner surface. 5. The apparatus of claim 3 wherein the probe means are pairs of first probes in electrical contact with the inner surface and at least one pair of second probes in electrical contact with the reference section, and the pairs of first probes bound the scored section and smooth section. 6. The apparatus of claim 4 wherein the probe means are at least one pair of first probes in electrical contact with the inner surface and at least one pair of second probes in electrical contact with the reference section, and the first probes bound the channel. 7. An apparatus for monitoring the corrosion of zirconium alloy members in a nuclear reactor core comprising: 8. The sensor of claim 7 in which the sensor member and rod has the same crystalline texture as the zirconium alloy member. 9. The sensor of claim 7 wherein the probes and the first and second leads are comprised of platinum wire insulated with an outer sheath comprised of ceramic material. 10. The apparatus of claim 7 wherein the outer surface of the sidewall means has a scored section and a smooth section.
041683943	claims	1. In combination: a concrete wall capable of shielding radiation; a penetration nozzle piercing said wall from side to side; an annular flange fixed on one end of said nozzle; a header plate removably mounted to said flange; an annular gasket disposed between said flange and said plate; said gasket having a pair of opposing surfaces and each surface having an annular groove formed therein; said gasket having at least one aperture communicating with both of said grooves; said header plate having at least one transverse bore wherein said bore has two cylindrical bore sections of different diameters connected by a tapered bore section with the larger of the cylindrical bore sections disposed removed from said nozzle; said header plate having a first passageway communicating with said tapered section and having one end extending to an exterior surface of said plate, and said plate having a second passageway communicating with said first passageway and having one end extending to the surface of said plate adjacent to said flange and communicating with said grooves; an electric penetration assembly disposed within said transverse bore of said plate; sealing means disposed between said plate and said assembly and within said tapered section; a retaining ring removably clamped to said plate and securing said assembly to said plate. an electrical conductor; an insulator disposed around said conductor with both ends of said conductor exposed; said insulator having two cylindrical surfaces disposed on each side of a conical surface and said conical surface being disposed substantially at the middle thereof; a gas permeable pervious means disposed in said insulator and between the ends thereof; an annular flexible end cap permanently bonded to each end of said insulator and to said conductor. an annular disc made of a porous ceramic; and said disc is disposed within said conical section. an annular thin metal member and shaped so that the outer periphery is bonded to said insulator and the inner periphery is bonded to said conductor. said insulator having a T-shaped duct formed therein and having one duct disposed parallel to said conductor and having the other duct communicating with said first duct and opening at the exterior surface of said tapered section. an annular thin metal member and shaped so that the outer periphery is bonded to said insulator and the inner periphery is bonded to said conductor. said insulator having a zigzag duct terminating against said conductor and opening at the exterior surface of said tapered section. an annular thin metal member and shaped so that the outer periphery is bonded to said insulator and the inner periphery is bonded to said conductor. a plurality of parallelly spaced conductors; an insulator disposed around said conductors with both ends of said conductors exposed; said insulator having a conical surface and two cylindrical surfaces disposed on each side of said conical surface; said insulator comprised of a solventless silicone resin with a filler material of between 60 to 75 percent by weight of said resin; said filler material selected from the group consisting of alumina, barium titanate, silica and magnesia, all in a powdered form; said insulator also comprised of a porous ceramic disc disposed between said silicone resin and within said conical surface. 2. An electrical penetration assembly comprising: 3. The assembly of claim 2 wherein said gas permeable means comprises: 4. The assembly of claim 3 wherein each of said end caps comprises: 5. The assembly of claim 2 wherein said gas permeable means comprises: 6. The assembly of claim 5 wherein each of said end caps comprises: 7. The assembly of claim 2 wherein said gas permeable means comprises: 8. The assembly of claim 7 wherein each of said end caps comprises: 9. An electrical penetration assembly comprising:
053032764	claims	1. A fuel assembly, comprising: (a) a lattice member defining a plurality of rhombic-shaped rod cells and a plurality of generally rhombic-shaped thimble cells therethrough; (b) a plurality of fuel rods, each of said fuel rods extending through respective ones of the rod cells; (c) a plurality of thimble tubes, each of said thimble tubes extending through respective ones of the thimble cells; and (d) deflector means associated with each of the rod cells and attached to said lattice member and protruding over its associated rod cell for deflecting a liquid component of a fluid stream about said fuel rod extending through the rod cell. (a) a lattice member having a hexagonally-shaped transverse contour, said lattice member defining a plurality of rhombic-shaped rod cells and a plurality of generally rhombic-shaped thimble cells therethrough; (b) a plurality of elongate fuel rods disposed in spaced parallel array, each of said fuel rods extending through respective ones of the rod cells; (c) a plurality of elongate thimble tubes disposed in spaced parallel array, each of said thimble tubes extending through respective ones of the thimble cells; and (d) a deflector vane associated with each of the rod cells and integrally attached to said lattice member and curvilinearly protruding over its associated rod cell obliquely to the fluid stream for deflecting a component of the fluid stream about each of said fuel rods. (a) a lattice member, including: (b) a plurality of elongate fuel rods disposed in spaced parallel array in the fluid stream and extending through respective ones of the rod cells, each of said fuel rods having a longitudinal axis parallel to the flow axis of the fluid stream; (c) a plurality of elongate thimble tubes disposed in spaced parallel array in the fluid stream and extending through respective ones of the thimble cells, each of said thimble tubes having a longitudinal axis parallel to the flow axis of the fluid stream; and (d) a plurality of deflector vanes associated with each of the rod cells, each of said deflector vanes integrally attached to said lattice member and curvilinearly protruding over its associated rod cell obliquely to the flow axis of the fluid stream for deflecting a component of the fluid stream about the longitudinal axis of said fuel rod extending through the associated rod cell. (a) a first tie plate; (b) a second tie plate spaced-apart from and coaxially aligned with said first tie plate; (c) a plurality of spaced-apart and coaxially aligned lattice members interposed between said first tie plate and said second tie plate, each of said lattice members including: (b) a plurality of elongate generally cylindrical fuel rods disposed in spaced parallel array in the fluid stream and capable of generating heat, each of said fuel rods interposed between said first tie plate and said second tie plate and having a longitudinal axis parallel to the flow axis of the fluid stream, each of said fuel rods extending through respective ones of the rod cells; (c) a plurality of elongate generally cylindrical thimble tubes disposed in spaced parallel array in the fluid stream, each of said thimble tubes interposed between said first tie plate and said second tie plate and having a first end portion connected to said first tie plate and a second end portion connected to said second tie plate for interconnecting said first tie plate and said second tie plate, each of said thimble tubes having a longitudinal axis parallel to the flow axis of the fluid stream, each of said thimble tubes extending through respective ones of the thimble cells; and (d) a plurality of deflector vanes associated with each of the rod cells, each of said deflector vanes attached to said lattice member and curvilinearly protruding over its associated rod cell obliquely to the flow axis of the fluid stream for deflecting a component of the fluid stream about the longitudinal axis of said fuel rod extending through the associated rod cell, whereby the rhombic shape of each rod cell and the curvature of each protruding deflector vane coact to obtain liquid substantially single-phase fluid flow over said fuel rod to transfer the heat from said fuel rod to the fluid stream as said deflector vane deflects the component of the fluid stream about the longitudinal axis of said fuel rod. 2. The fuel assembly according to claim 1, wherein said deflector means curvilinearly protrudes over its associated rod cell. 3. The fuel assembly according to claim 2, wherein said deflector means is a pair of deflector vanes. 4. A fuel assembly capable of deflecting a component of a liquid fluid stream flowing past the fuel assembly, comprising: 5. The fuel assembly according to claim 4, further comprising a second deflector vane associated with each of the rod cells and integrally attached to said lattice member and curvilinearly protruding over its associated rod cell obliquely to the fluid stream for deflecting a component of the fluid stream about each of said fuel rods. 6. A fuel assembly capable of deflecting a component of a liquid fluid stream flowing past the fuel assembly, the fluid stream having a flow axis, the fuel assembly comprising: 7. The fuel assembly according to claim 6, wherein each of said plurality of deflector vanes helically curvilinearly protrudes over its associated rod cell for causing a vortex so that the component of the fluid stream deflected about the fuel rod swirls about the longitudinal axis of said fuel rod. 8. The fuel assembly according to claim 7, wherein said plurality of deflector vanes is a pair of oppositely oriented deflector vanes offset one from the other for causing two vortices, so that the component of the fluid stream deflected about the longitudinal axis of said fuel rod obtains greater swirling action. 9. In a nuclear reactor core having a liquid fluid stream flowing therethrough, the fluid stream having a unidirectional flow axis, a fuel assembly capable of deflecting a component of the fluid stream flowing past the fuel assembly, the fuel assembly comprising: 10. The fuel assembly according to claim 9, wherein each deflector vane helically curvilinearly protrudes over its associated rod cell for swirling the component of the fluid stream about the longitudinal axis of said fuel rod to transfer the heat from said fuel rod to the fluid stream. 11. The fuel assembly according to claim 10, further comprising two oppositely oriented deflector vanes offset one from the other for causing two vortices, so that the component of the fluid stream deflected about the longitudinal axis of the fuel rod obtains greater swirling action to transfer more of the heat from said fuel rod to the fluid stream.
	summary
	description	The present invention may be implemented, for example, via FORTRAN computer program code executed using Digital Equipment Corp. Alpha computers running the Open VMS operating system. As embodied in a computer program for execution on a computer, the present invention determines actual power histories of each fuel rod in the reactor core using empirical data acquired from past operation of the reactor and evaluates the internal pressure for each fuel rod for an upcoming fuel cycle. Preferably, this rod evaluation process is performed during the fuel cycle design and licensing process for each operating cycle of a particular nuclear reactor. The evaluation process includes a rod-by-rod internal pressure analysis based on empirical data of actual operational power output levels of each fuel rod in the reactor core. A computer program constructs individual fuel rod power histories for each nuclear fuel rod in the reactor core based on information acquired during previous fuel cycles and a projected operation of the reactor in an upcoming fuel cycle. Using the constructed power histories for each fuel rod, the program then computes thermal and mechanical overpower limits and the maximum internal pressure for each rod in the upcoming fuel cycle. Licensing compliance is demonstrated by confirming that the computed maximum internal pressure for the upcoming fuel cycle is less than the critical pressure with a statistical confidence mandated by the regulatory agency and that the maximum thermal and mechanical overpower stresses of the fuel rods are below regulatory maximums. FIG. 1 shows a graph illustrating an example thermal-mechanical limit envelope 10 for evaluating fuel rods. The envelope represents the operating limit maximum linear heat generation rate (MLHGR) for a fuel rod as function of fuel pellet exposure. FIG. 2 shows a simplified block diagram of an example data processing system, 100, contemplated for performing the evaluation of fuel rod thermal-mechanical limits for each rod in a reactor core in accordance with the method of the present invention. Essentially, system 100 includes CPU 101, storage memory 102, and user interfacing I/O devices 103 and optionally one or more displays 104. Storage memory 102 includes a database or files (not shown) containing, for example, reactor plant initial state information, fuel lattice physics analysis results, 3D simulation results, fuel rod type/characteristics data and a program for evaluating fuel rods in accordance with the method of the present invention. FIG. 3 shows a mathematical relationship useful for computing an internal pressure ratio of a fuel rodxe2x80x94for producing pressure ratio values believed reliable to a 95% degree of confidence. The Pressure Ratio value obtained using this equation is based on the ratio between a maximum nominal internal pressure, Pmax,nom, and a nominal critical internal pressure, Pcrit,nom, for a fuel rod. Pmax,nom may be determined by performing a conventional T-M type analysis on a fuel rod, for example, as produced by GE""s GESTR performance software. FIG. 4 shows a functional program flow diagram of an example embodiment of the fuel rod evaluation program of the present invention. Each block of the diagram contains a concise explanation of a functional step performed, for example, by a computer program operating on a single or multi-processor computer system for the purpose of evaluating the thermal-mechanical limits for all fuel rods in a reactor core. One of ordinary skill will appreciate that the illustrated functional steps of FIG. 4, although explained in greater detail below, are essentially self explanatory and may be implemented on a conventional computer by utilizing conventional programming techniques and programming tools well known in the art. As illustrated by the functional flow diagram of FIG. 4, the method of the present invention essentially involves examining all fuel rods within each fuel bundle in a reactor core on a rod-by-rod basis to determine internal pressure data for each fuel rod and then using that information to set appropriate limiting operational criteria for the reactor. First, fuel rod power xe2x80x9chistoriesxe2x80x9d are constructed based on operating data from reactor process computers and data provided from pre-assembled data files (e.g., reactor 3D simulation files 304, reactor fuel lattice physics analysis files 306, and T-M analysis files 312). The reactor specific information provided by these data files may be pre-acquired and digitally stored by conventional means using standard procedures and processes well known in the nuclear industry. The fuel rod power histories are then used to perform T-M analysis for each rod individually. Referring to program flow diagram 300 of FIG. 4, fuel bundle xe2x80x9chistoriesxe2x80x9d, block 302, are first constructed using xe2x80x9chistoricalxe2x80x9d fuel-cycle data stored in a set of stored input files 304 (e.g., GE""s PANAEA CEDAR files). This historical fuel-cycle data is produced as a result of running 3D simulations of the reactor for operating conditions covering previous fuel cycles (e.g., cycle nxe2x88x923 through cycle nxe2x88x921) and the projected operating conditions for the upcoming cycle (cycle n). At this time, other reactor specific operational parameters relevant to constructing fuel bundle histories may be input as user data 301. The bundle histories so constructed may comprise, for example, fuel rod axial power rating (P), fuel rod exposure data (Exp), water density history (UH) and control fraction data (CF). Next, at block 308, individual fuel rod power histories are developed using the constructed fuel bundle history data and data obtained from a second set of input files 306 (containing reactor fuel lattice analysis data (e.g., GE""s TGBLA files). Next, at block 310, T-M analysis input files are constructed for running T-M analysis cases using a third set of input files 312 containing fuel rod specific data (e.g., GE""s GSTRM files). Next, at block 314, the T-M analysis cases for each rod are run and output files are produced. Finally, at block 316, the T-M output files are processed to provide output results, block 318, for each fuel rod for printing or display and then a next fuel bundle is examined. Output results 318 include at least peak pressure and exposure data for such rod and may further include other relevant information such as: end-of-life pressure/exposure, maximum exp./mode, maximum enrichment/GAD. This process continues until all bundles in the core are evaluated. FIG. 5 shows an example listing of rod-by-rod output results provided in the preferred implementation of the present invention.
	abstract	Articles, such as tubing or strips, which have excellent corrosion resistance to water or steam at elevated temperatures, are produced from alloys having 0.2 to 1.5 weight percent niobium, 0.01 to 0.6 weight percent iron, and optionally additional alloy elements selected from the group consisting of tin, chromium, copper, vanadium, and nickel with the balance at least 97 weight percent zirconium, including impurities, where a necessary final heat treatment includes one of i) a SRA or PRXA (15-20% RXA) final heat treatment, or ii) a PRXA (80-95% RXA) or RXA final heat treatment.
	claims	1. A boiling water reactor vessel having a feedwater sparger with a constrained feedwater sparger end bracket assembly, comprising:a boiling water reactor vessel having a vessel wall;a feedwater sparger within said boiling water reactor vessel and including a conduit spaced inwardly from said vessel wall and having a conduit end;a feedwater sparger end bracket assembly connected to said conduit end at a sparger/bracket junction; anda clamp disposed on said feedwater sparger end bracket assembly and consisting of a one-piece first clamp member having a first compartment receiving a first portion of said sparger/bracket junction, a one-piece second clamp member, in opposition to said first clamp member, having a second compartment receiving a second portion of said sparger/bracket junction, and a connector securing said first clamp member and said second clamp member on said feedwater sparger end bracket assembly with said first compartment and said second compartment constraining said sparger/bracket junction against separation. 2. The boiling water reactor vessel having a feedwater sparger with a constrained feedwater sparger end bracket assembly as recited in claim 1 wherein:said first clamp member includes a pair of spaced shoulders;said second clamp member includes a pair of spaced shoulders; andsaid feedwater sparger end bracket assembly is disposed and constrained between said shoulders of said first clamp member and between said shoulders of said second clamp member. 3. The boiling water reactor vessel having a feedwater sparger with a constrained feedwater sparger end bracket assembly as recited in claim 1 wherein:said first clamp member includes a first shoulder disposed between said feedwater sparger end bracket assembly and said vessel wall, a tab spaced from said shoulder and disposed between said conduit and said vessel wall, and a second shoulder spaced inwardly from said first shoulder and from said tab, said second shoulder being disposed between said first shoulder and said tab;said second clamp member includes a first shoulder disposed between said feedwater sparger end bracket assembly and said vessel wall, a tab spaced from said first shoulder of said second clamp member and disposed between said conduit and said vessel wall, and a second shoulder spaced inwardly from said first shoulder of said second clamp member and from said tab of said second clamp member, said second shoulder of said second clamp member being disposed between said first shoulder of said second clamp member and said tab of said second clamp member;said feedwater sparger end bracket assembly is disposed and constrained between said first shoulders and said second shoulders; andsaid conduit is disposed and constrained between said second shoulders and said tabs. 4. The boiling water reactor vessel having a feedwater sparger with a constrained feedwater sparger end bracket assembly as recited in claim 1 wherein:said sparger/bracket junction comprises an end plate at said conduit end, and an attachment plate of said feedwater sparger end bracket assembly secured to said end plate;said first portion of said sparger/bracket junction comprises first portions of said end plate and said attachment plate received together in said first compartment; andsaid second portion of said sparger/bracket junction comprises second portions of said end plate and said attachment plate received together in said second compartment. 5. The boiling water reactor vessel having a feedwater sparger with a constrained feedwater sparger end bracket assembly as recited in claim 4 wherein said sparger/bracket junction further comprises a shim plate disposed between said end plate and said attachment plate. 6. A boiling water reactor vessel having a feedwater sparger with a constrained feedwater sparger end bracket assembly comprising:a boiling water reactor vessel having a vessel wall;a feedwater sparger within said boiling water reactor vessel and including a conduit spaced inwardly from said vessel wall and having a conduit end;a feedwater sparger end bracket assembly connected to said conduit end at a sparger/bracket junction having an upper portion and a lower portion; anda clamp secured on said sparger/bracket junction and consisting of a one-piece upper clamp member, a one-piece lower clamp member, and a connector securing said clamp members on said sparger/bracket junction;said upper clamp member having an upper clamp member compartment receiving said upper portion of said sparger/bracket junction between opposed internal walls of said compartment to constrain said feedwater sparger end bracket assembly in a first direction, having an internal top wall of said compartment disposed over said upper portion to constrain said feedwater sparger end bracket assembly in a second direction, and having inner and outer shoulders receiving said feedwater sparger end bracket assembly therebetween to constrain said feedwater sparger end bracket assembly in a third direction; andsaid lower clamp member having a lower clamp member compartment receiving said lower portion of said sparger/bracket junction between opposed internal walls of said lower clamp member compartment to constrain said feedwater sparger end bracket assembly in said first direction, having an internal bottom wall of said lower clamp member compartment disposed beneath said lower portion to constrain said feedwater sparger end bracket assembly in said second direction, and having inner and outer shoulders receiving said feedwater sparger end bracket assembly therebetween to constrain said feedwater sparger end bracket assembly in said third direction. 7. The boiling water reactor vessel having a feedwater sparger with a constrained feedwater sparger end bracket assembly as recited in claim 6 wherein:said first direction is horizontal to said vessel;said second direction is vertical to said vessel; andsaid third direction is radial to said vessel. 8. The boiling water reactor vessel having a feedwater sparger with a constrained feedwater sparger end bracket assembly as recited in claim 6 wherein said sparger/bracket junction comprises:an end plate at said conduit end; andan attachment plate of said feedwater sparger end bracket assembly secured to said end plate. 9. The boiling water reactor vessel having a feedwater sparger with a constrained feedwater sparger end bracket assembly as recited in claim 8 wherein said sparger/bracket junction further comprises a shim plate between said end plate and said attachment plate. 10. The boiling water reactor vessel having a feedwater sparger with a constrained feedwater sparger end bracket assembly as recited in claim 6 wherein:said upper clamp member further comprises a shear tab disposed between said conduit and said vessel wall; andsaid lower clamp member further comprises a shear tab disposed between said conduit and said vessel wall. 11. The boiling water reactor vessel having a feedwater sparger with a constrained feedwater sparger end bracket assembly as recited in claim 10 wherein:said shoulders are located on one side of said sparger/bracket junction; andsaid shear tabs are located on an opposite side of said sparger/bracket junction. 12. The boiling water reactor vessel having a feedwater sparger with a constrained feedwater sparger end bracket assembly as recited in claim 6 wherein said connector draws said clamp members toward one another in said second direction. 13. A boiling water reactor vessel having a feedwater sparger with a constrained feedwater sparger end bracket assembly comprisinga boiling water reactor vessel including a vertically extending vessel wall of cylindrical curvature;a feedwater sparger within said vessel and including a circumferentially extending conduit spaced inwardly from said vessel wall and having a conduit end;a feedwater sparger end bracket assembly connected to said vessel wall and to said conduit end, said feedwater sparger end bracket assembly being connected to said conduit end at a sparger/bracket junction, said sparger/bracket junction comprising a planar end plate at said conduit end, and a planar attachment plate of said feedwater sparger end bracket assembly connected to said end plate in parallel relation with said end plate, said end plate and said attachment plate extending vertically within said vessel; anda clamp secured on said sparger/bracket junction and consisting of a one-piece upper clamp member, a one-piece lower clamp member and a connector securing said clamp members on said sparger/bracket junction;said upper clamp member having an upper clamp member compartment receiving upper portions of said end plate and said attachment plate together between opposed internal walls of said compartment to constrain said feedwater sparger end bracket assembly in a direction horizontal to said vessel, having an internal top wall of said compartment disposed over said upper portions of said end plate and said attachment plate to constrain said feedwater sparger end bracket assembly in a direction vertical to said vessel and having inner and outer shoulders receiving said feedwater sparger end bracket assembly therebetween to constrain said feedwater sparger end bracket assembly in a direction radial to said vessel;said lower clamp member having a lower clamp member compartment receiving lower portions of said end plate and said attachment plate together between opposed internal walls of said lower clamp member compartment to constrain said feedwater sparger end bracket assembly in said direction horizontal to said vessel, having an internal bottom wall of said lower clamp member compartment disposed beneath said lower portions of said end plate and said attachment plate to constrain said feedwater sparger end bracket assembly in said direction vertical to said vessel, and having inner and outer shoulders receiving said feedwater sparger end bracket assembly therebetween to constrain said feedwater sparger end bracket assembly in said direction radial to said vessel; andsaid connector drawing said clamp members toward one another in said direction vertical to said vessel. 14. The boiling water reactor vessel having a feedwater sparger with a constrained feedwater sparger end bracket assembly as recited in claim 13 wherein said end plate is welded to said attachment plate. 15. The boiling water reactor vessel having a feedwater sparger with a constrained feedwater sparger end bracket assembly as recited in claim 13 wherein said sparger/bracket junction further comprises a shim plate disposed between and welded to said end plate and said attachment plate. 16. The boiling water reactor vessel having a feedwater sparger with a constrained feedwater sparger end bracket assembly as recited in claim 13 wherein:said attachment plate has a rearward face connected to said end plate and has a forward face opposite said rearward face;said reactor vessel further comprises an attachment fitting extending inwardly from said vessel wall; andsaid feedwater sparger end bracket assembly further comprises an upper bracket member extending from said forward face, a lower bracket member extending from said forward face in the same direction as said upper bracket member with said fitting disposed between said bracket members, and a pin extending through said bracket members and said fitting;said outer shoulder of said upper clamp member being disposed between said upper bracket member and said vessel wall; andsaid outer shoulder of said lower clamp member being disposed between said lower bracket member and said vessel wall. 17. The boiling water reactor vessel having a feedwater sparger with a constrained feedwater sparger end bracket assembly as recited in claim 16 wherein:said upper clamp member further comprises a shear tab disposed between said conduit and said vessel wall; andsaid lower clamp member further comprises a shear tab disposed between said conduit and said vessel wall. 18. The boiling water reactor vessel having a feedwater sparger with a constrained feedwater sparger end bracket assembly as recited in claim 16 wherein:said inner shoulders are adjacent said attachment plate; said upper clamp member further comprises a shim pad disposed between said conduit and said inner shoulder of said upper clamp member; andsaid lower clamp member further comprises a shim pad disposed between said conduit and said inner shoulder of said lower clamp member. 19. The boiling water reactor vessel having a feedwater sparger with a constrained feedwater sparger end bracket assembly as recited in claim 18 wherein:said upper clamp member further comprises a spacer disposed between said end plate and said inner shoulder of said upper clamp member; andsaid lower clamp member further comprises a spacer disposed between said end plate and said inner shoulder of said lower clamp member. 20. The boiling water reactor vessel having feedwater sparger with a constrained feedwater sparger end bracket assembly as recited in claim 16 wherein;said upper clamp member further comprises an impingement shield extending downwardly toward said lower clamp member;said lower clamp member further comprises an impingement shield extending upwardly toward said upper clamp member; andsaid impingement shields are in overlapping engagement and are disposed between said sparger/bracket junction and said vessel wall.
052689433	abstract	A pressurized water nuclear reactor uses its residual heat removal system to make up water in the reactor coolant circuit from an in-containment refueling water supply during staged depressurization leading up to passive emergency cooling by gravity feed from the refueling water storage tank, and flooding of the containment building. When depressurization commences due to inadvertence or a manageable leak, the residual heat removal system is activated manually and prevents flooding of the containment when such action is not necessary. Operation of the passive cooling system is not impaired. A high pressure makeup water storage tank is coupled to the reactor coolant circuit, holding makeup coolant at the operational pressure of the reactor. The staged depressurization system vents the coolant circuit to the containment, thus reducing the supply of makeup coolant. The level of makeup coolant can be sensed to trigger opening of successive depressurization conduits. The residual heat removal pumps move water from the refueling water storage tank into the coolant circuit as the coolant circuit is depressurized, preventing reaching the final depressurization stage unless the makeup coolant level continues to drop. The residual heat removal system can also be coupled in a loop with the refueling water supply tank, for an auxiliary heat removal path.
	abstract	The invention provides at least two electrochemical sensors positioned in a nuclear reactor or in a system adjacent to the nuclear reactor, wherein at least one of the at least two electrochemical sensors has a heated zirconium electrode, and the at least two electrochemical sensors produce voltages proportional to an electrochemical corrosion potential for a surface that each of the at least two electrochemical sensors are installed upon. The invention also provides an arrangement configured to accept the voltages produced by the at least two electrochemical sensors, wherein the arrangement is configured to determine an electrochemical corrosion potential of a zirconium fuel rod in the nuclear reactor based upon the voltages of the at least two electrochemical sensors.
	description	This application claims benefits and priority of provisional application Ser. No. 61/277,659 filed Sep. 28, 2009, the disclosure of which is incorporated herein by reference. This invention was made with government support under Grant No. CBET-0730976 awarded by the National Science Foundation. The Government has certain rights in the invention. The present invention relates to a UV (ultraviolet) light disinfectant apparatus useful with a biofilm flow cell or other bioreactor for in-line, non-invasive disinfecting of influent medium to the biofilm flow cell. Bioflim flow cells (biofilm culturing devices) have been used to grow surface-attached microbial communities (biofilms) under pre-specified, complex flow conditions including both spatial and temporal variability in influent flows, nutrient levels, substrates, etc. as a result of workers recognizing that microbial communities on interfaces, termed biofilms, are extremely important in a wide variety of environmental, engineered, and biomedical uses. Biofilms are responsible for more than half of microbial infections, and these infections are highly problematic because cells in bioflims are typically more than 500 times resistant to antimicrobial therapy than planktonic cells. Moreover, bioflims play a significant role in global biogeochemical cycling and in bioreactor systems by changing properties of interfaces, consuming nutrients, degrading hazardous organic compounds, and immobilizing metals. Normally, in-line filters or flow breaks are used to prevent growth of bacteria upstream of laboratory culturing devices, such as flow cells. However, these sorts of in-line devices are prone to clogging because of either microbial colonization or deposition of material from the influent growth medium. This normally restricts the duration of laboratory experiments involving biofilms to a few days, or a week at most. Such filters or in-line controls have been found to adversely affected flow conditions, especially when used in connection with planar (two-dimensional) flow cells. The present invention provides an in-line, non-invasive UV light disinfectant apparatus and method useful with a biofilm flow cell or other bioreactor for in-line, non-invasive disinfecting of influent medium to the biofilm flow cell. In an illustrative embodiment of the invention, the UV light disinfectant apparatus comprises a UV chamber having a UV (ultraviolet) light source therein and one or more UV light-transmissive tubes, such as capillary tubes, that extend through the UV chamber and through which the influent medium flows through the UV chamber for exposure to UV light. The apparatus includes light reflecting walls that define the UV chamber to expose the influent medium in the capillary tubes to direct and reflected UV light. A plurality of capillary tube assemblies can be employed above and below the UV light source with each capillary tube assembly being configured to provide multiple passes of the influent medium through the UV chamber. For example, each capillary tube assembly can include multiple glass capillary tubes and one or more U-bend connector tubing sections that redirect the influent medium to flow back through the UV chamber in the opposite direction from the direction in which the fluid medium entered the UV chamber. The present invention envisions a disinfection system including a combination of a biofilm reactor, such as a biofilm flow cell, placed in-line with the inflow tubing and optionally outflow tubing that goes to/from the flow cell. The flow cell receives the influent medium from the UV disinfectant apparatus described above that is effective in preventing growth of bacteria (non-invasively kill bacteria) without inducing any disruption of the influent (inflow) or effluent (outflow). The UV disinfection system is effective to non-invasively kill bacteria in the inflow and outflow tubing. The in-line UV disinfection system is advantageous to enable continuous operation of small-scale, flow-through microbial culture systems. No filters or similar devices are required such that precise flow control can be maintained to the flow cell. Other advantages of the present invention will become more readily apparent from the following drawings taken with the following detailed description. Referring to FIGS. 1A and 1B, the present invention provides an in-line, non-invasive UV light disinfectant apparatus and method useful with a biofilm flow cell or other bioreactor for in-line, non-invasive disinfecting of influent medium supplied to the biofilm flow cell. For example, FIG. 1A schematically illustrates a disinfection system including a source of an influent fluid medium (e.g. a bottle containing fluid growth medium) 10, an influent medium pump 12, a bubble trap 14, a UV disinfection apparatus 16 pursuant to the invention, a bioreactor 18 such as planar biofilm flow cell, and a bio-waste (effluent) bottle 20. FIG. 1B is a similar system but includes multiple bubble traps 14 upstream of respective UV disinfection apparatus 16 pursuant to the invention, and multiple planar flow cells 18 supplied with the influent medium via a respective UV disinfection unit 16. In an illustrative embodiment of the invention shown in FIGS. 2A-2C; 3A, 3B; and 4A, 4B, the UV disinfectant apparatus 18 comprises a UV chamber 30 having a UV light source 32 therein and one or more UV light-transmissive tubes 34t that extend through the UV chamber 30 and through which the influent medium flows through the UV chamber for exposure to UV light. The UV chamber 30 is formed in a housing 40 having a pair of upstanding sidewalls 40a, an apertured top wall 40b, a solid bottom wall 40c an apertured end wall 40d, and solid end wall 40e. An apertured divider or support frame 43 is provided on opposite ends of the UV chamber. End wall 40d includes a cylindrical pen light support hub 42 that receives the elongated UV light source 32 in the form an elongated UV pen light 32 and air inlet apertures 44. The pen light extends through a passage 45p of a pen light support block 44 attached in the UV chamber and then into the UV chamber 30, FIGS. 2A, 2B, 2C. UV light can have a wavelength in the range of about 10 nm to about 400 nm for purposes of illustration and not limitation. The block 44 has cut-outs that define air inlet paths that communicate with inlet apertures 44 of the end wall 40d. End wall 40e is solid. One or more covers 50 (two shown) is/are disposed on top of the sections of the housing 40 to close off the UV chamber 30 as shown. For purposes of illustration and not limitation, the UV pen light can comprise a Pen-Ray® Mercury lamp (254 nm wavelength) from McMaster Carr (part no. 90-0012-01). The walls and covers 50 of the housing 40 can be made of 0.25 inch thick acrylic plates with the walls glued or otherwise fastened together. The walls and cover(s) of the housing are painted with flat, black acrylic paint to make them non-transmissive to light. Also, the walls and covers can be made of 0.25 inch thick black, opaque acrylic, which does not have to be painted, as it already blocks UV light (McMaster Carr part no. 8650K321). The inside surfaces of the UV chamber 30 are lined with light reflective material 51, such as Mylar film or laser-cut mirrored acrylic material (McMaster Carr part no. 1518T52), in order to reflect the UV light so as to expose the influent medium in the capillary tubes 34t to direct and reflected UV light for increased efficiency in killing bacteria. The inner surfaces of the bottom wall, sidewalls, and end walls of the housing 40 can be lined to this end. The inner surface of the covers 50 can be lined to this same end. The reflective material is laser-cut (using a computer-controlled laser cutting machine) to match the dimension of the internal surfaces and to provide additional reflection of scattered light. Also, the inner surfaces of the reducer plates 41 described below are lined to this end as well. The reflective material is laser-cut to match the dimensions of the reducer plates. The objective is to make any internal surface, except holes and cut-outs, exposed to UV light capable of reflecting light. An air outlet chamber 60 is formed in the end region of the housing closed off by end wall 40e. An exhaust fan 70 is mounted on the top wall 40b of the housing 40 above the chamber 60 using four fan mounting screw holes 40s to draw air through end wall air inlets 44, through the UV chamber 30 and out of the chamber 60 as directed by a fixed diagonal air deflector 72 to control temperature within the UV chamber 30 in a desired range. The top housing wall 40b includes an aperture 40g to provide an air flow opening out of the chamber 60. The other two apertures shown in the housing top wall 40a are access openings, which are closed off by the covers 50. The covers correspond to the dimensions of the respective apertures. when they are attached on top of the housing. The sidewalls 40a of the housing include holes 40p that receive the larger outer diameter inflow tubing from a respective bubble trap 14 and outflow tubing to the respective flow cell 18. Reducer plates 41 are disposed on and fastened by adhesive or other means to the inner side of each sidewall 40a and include holes 41p of smaller outer diameter than hole 40p to receive tubing reducer fittings 74 that have a smaller inner diameter to receive the ends of the tube assemblies as shown best in FIGS. 2A, 2B, and 2C where a pair of capillary tube assemblies 34 are shown mounted in the upper holes 41 p and another pair of capillary tube assemblies 34 are mounted in the lower holes 41p so as to reside above and below the UV pen light 32 in the UV chamber 30 and extending generally perpendicular thereto. The ends of the capillary tubes 34t can be inserted into a respective tubing reducer fitting 74, which has an inner diameter that matches the outer diameter of the capillary tube 34t and an outer diameter matching the inner diameter of the respective inflow or outflow tubing as appropriate. The reducer fittings 74 aid in preventing the escape of scattered UV light as well as provide mechanical support for the capillary tube assemblies. Each capillary tube assembly 34 comprises three transparent glass capillary tubes 34t connected at ends by two flexible U-bend connector tubing 34c as shown in FIGS. 2A, 2B, 2C. For purposes of illustration and not limitation, the glass capillary tubes 34t can comprise 0.4 mm ID/75 mm long glass capillary tubes available from Drummond Scientific (part no. 1-000-800). The flexible connector tubing 34c can comprise 0.094 inch/0.156 inch OD C-Flex tubing available from Cole-Parmer (part no. 06422-03). The capillary tubes 34 have their ends received in the reducer fittings 74, FIGS. 2A, 2B, 2C which are disposed in the holes 40p so as to mount the capillary tubes 34t to extend across the UV chamber 30. The reducer fittings are available from Cole-Parmer (part no. 6365-50). The two U-bend connector tubing sections 34c of each capillary tube assembly 34 redirect the influent fluid medium to flow back through the UV chamber 30 in the opposite direction from the direction in which the fluid medium entered the UV chamber. Referring to FIGS. 2A, 2B, and 2C, it is apparent that each capillary tube assembly 34 provides three passes of the influent medium through the UV chamber 30, although the capillary tube assemblies can have other configurations to provide fewer or more passes through the UV chamber. After the capillary tubes 34 are assembled on the housing, the covers 50 are attached by screws or other releasable fastening devices with its middle light reflective section overlying the UV chamber 30. A protective rubber sheet can be cut with appropriate apertures and fitted between the covers 50 and the top wall 40a of the housing. FIG. 5 illustrates disinfection efficiency of the in-line UV disinfection system. in continuous experiments ran in parallel, one with a UV disinfection apparatus as described above, and the other one without, as a negative control. Results of FIG. 5 are presented for four different initial concentrations of inoculated cells. Killing was very efficient in all cases using UV, with 100% killing found for influent concentrations on the order of 103-104 CFU/ml. After five days, bacterial growth was detected in the control, visible biofilm growth inside the upstream tubing and associated clogging. No bacterial growth was detected upstream of the UV apparatus after eleven days of continuous operation. The UV disinfection apparatus was shown to be effective at preventing microbial upstream growth inside the connective tubing. The non-invasive disinfection apparatus provides a means of supporting continuous system operation without the need for disruption of the flow path (i.e., no filters or similar devices are required, so precise flow control can be maintained). In addition to the research uses, the invention can find use in biofilm control in industrial settings and also in treating biofilm-based infections. As a result, there is a broad applicability for testing devices capable of simulating various environments where biofilms are found in order to evaluate the effectiveness of new biocides and other control measures. In addition, bioreactors are used to achieve desirable chemical transformations in a wide variety of applications, including wastewater treatment, bioremediation, chemical processing, pharmaceuticals, and others. Although the present invention has been described in connection with certain illustrative embodiments thereof, those skilled in the art will appreciate that changes and modifications can be made thereto within the scope of the invention as set forth in the appended claims.
	claims	1. A lithography system in which an electronic image pattern is delivered to an exposure tool for projecting an image to a target surface, said exposure tool comprising:a control unit (60) and a modulator (24) for controlling exposure projections, said modulator at least partly being included in the projection space of said exposure tool and comprising a light sensitive part, wherein the control unit is adapted to provide the modulator with control data by means of modulated light beams emitted by an emitter part to the light sensitive part of said modulator,a free space optical interconnect arranged for coupling the modulated light beams into the light-sensitive part of the modulator,characterized in that the free space optical interconnect comprises a holed mirror having a reflective surface arranged for reflecting said modulated light beams towards the light sensitive part of the modulator for on-axis incidence on said light sensitive part, said hole or holes in the mirror being provided for passage of said exposure projections. 2. A system according to claim 1, in which the emitter part is incorporated in the system to emit said modulated light beams at least virtually perpendicular relative to a direction of said exposure projection. 3. A system according to claim 1, in which said free space interconnect is included at a downstream side of the control unit. 4. A system according to claim 1, in which said free space interconnect, including said emitter part and said holey mirror is included in a housing that is mechanically connected to the modulator. 5. A system according to claim 4, wherein said free space interconnect is connected to the modulator via a holder therefore. 6. A system according to claim 1, in which a focusing lens is incorporated in said free space optical interconnect in near proximity to said holey mirror. 7. A system according to claim 6, wherein the focusing lens is arranged significantly nearer to said mirror than to said emitter part. 8. A system according to claim 7, said focusing lens being common to all of the modulated light beams emitted by said emitter part. 9. A system according to claim 1, in which said holey mirror comprises a focusing reflecting surface. 10. A system according to claim 9, said reflecting surface being a concave surface. 11. A system according to claim 10 said mirror being common to all of the modulated light beams emitted by said emitter part. 12. A system according to claim 1, in which a micro lens is incorporated in said free space optical interconnect, in close proximity to a light carrier end. 13. A system according to claim 12, the micro lens forming said emitter part. 14. A system according to claim 12 wherein the micro lens is incorporated in said free space optical interconnect significantly closer to said carrier end than to said holey mirror. 15. A system according to claim 14, wherein each light carrier composing part is provided with a micro lens. 16. A system according to claim 1, wherein the free space optical interconnect comprises a micro lens and a focusing lens common to a possible plurality of micro-lens completed fibers, the micro lens therein magnifying a fiber transmitted light signal, and the focusing lens de-magnifying the entirety of light signals transmitted by said possible plurality of fibers. 17. A system according to claim 1, wherein said free space optical interconnect is included in between a modulator unit formed by a blanker array for blanking writing beams, and a stopping plate for stopping writing beams deflected by said blanker array. 18. A system according to claim 1, wherein one or more light signal carriers are fed through a vacuum wall for the exposure tool using vacuum compatible sealing material, and are with end parts thereof subsequently mechanically coupled to a free space optical connect housing located in a vacuum space for a charged particle beam column of the lithography system. 19. A lithography system in which an electronic image pattern is delivered by means of light projection to an exposure tool formed by a writing tool utilizing an multi-beam exposure projection system for mask-less projection of a pattern on to an exposure surface, said lithography system comprising:a vacuum housing within which said writing tool is incorporated,a multi-beam projection source adapted for creating a plurality of writing beams for writing said pattern, which writing beams are directed to a blanker array comprising a modulator unit with individual deflectors for individually deflecting a writing beam in accordance with received pattern information defining whether a beam should be deflected to a beam stopping part or not,a light optical system comprising light transmitting parts adapted for transmitting pattern information signals to said modulator unit,wherein said modulator unit comprises light sensitive elements for receiving modulated light beams, said light sensitive elements being accommodated within near vicinity of the deflectors,wherein said light optical system comprises a free space optical interconnect, forming a light optical data carrier system, adapted for transmitting pattern-data carrying, modulated light beams towards said modulator unit,wherein said free space optical interconnect comprises an emitter part adapted for emitting free space interconnect pattern-data carrying, modulated light beams to said light sensitive elements,wherein said free space optical interconnect comprises a holey mirror, incorporated in the projection trajectory of said plurality of writing beams,said mirror being arranged relative to said emitter part and said light sensitive elements to reflect the modulated light beams from the emitter part in on-axis incidence onto said light sensitive elements, andsaid mirror being provided with at least one hole allowing passage of one or more of said writing beams. 20. A lithography system in which an electronic image pattern is delivered to a writing tool of the system, by projection of modulated, data-carrying light beams (8) to said writing tool, and comprising a free space optical interconnect for finally delivering said image pattern to said writing tool, wherein said free space optical interconnect comprises a holed mirror with one or more holes, said mirror being included in said writing tool and arranged for reflecting said data-carrying, modulated light beams along the direction of projection of said writing tool and allowing passage of a writing tool projection through said hole or holes. 21. A system according to claim 20, comprising a vacuum housing incorporating the lithography system, said system further comprising a multi beam system for mask-less projection of a pattern on to an exposure surface. 22. Method of projecting light beams into a lithography system part, said method comprising a step ofreflecting pattern-data carrying, modulated light beams in a reflective surface of a holed mirror towards a light sensitive part of a modulator for modulating writing projections of said lithography system part, andprojecting writing projections of said lithography system part through the one or more holes in the holed mirror onto a target.
	abstract	A sample fabricating method of irradiating a sample with a focused ion beam at an incident angle less than 90 degrees with respect to the surface of the sample, eliminating the peripheral area of a micro sample as a target, turning a specimen stage around a line segment perpendicular to the sample surface as a turn axis, irradiating the sample with the focused ion beam while the incident angle on the sample surface is fixed, and separating the micro sample or preparing the micro sample to be separated. A sample fabricating apparatus for forming a sample section in a sample held on a specimen stage by scanning and deflecting an ion beam, wherein an angle between an optical axis of the ion beam and the surface of the specimen stage is fixed and formation of a sample section is controlled by turning the specimen stage.
	claims	1. A honeycomb storage device for at least one of storing and transporting containers of sensitive or volatile materials, comprising:a plurality of six-corner surface tubes arranged in parallel to each other to form a predetermined shape such that the plurality of six-corner surface tubes are longitudinally attached to each other and positioned in a honeycomb structure when viewed in cross-section, whereineach of the plurality of six-corner surface tubes includes a hollow internal tank, and is formed from pre-impregnated fibre-reinforced plastic (FRP prepreg) molded into the six-corner surface with a hexagonal shape in cross-section surrounding the hollow internal tank, the hollow internal tank being fixedly positioned inside of a corresponding six-corner surface tube and along a longitudinal axis of the corresponding six-corner surface tube, and the hollow internal tank being formed to contain at least one of sensitive and volatile materials, the FRP prepreg completely filling an internal space of each six-corner surface tube outside of the hollow internal tank. 2. A honeycomb storage device according to claim 1, further comprising:a plurality of elongated filler elements, whereineach of the plurality of elongated filler elements includes FRP prepreg molded with a four-corner surface longitudinally along each filler element with a trapezoidal shape in cross-section, the FRP prepreg completely filling an internal space of each elongated filler element,said plurality of six-corner surface tubes and said plurality of elongated filler elements are arranged into the predetermined shape such that the tubes and filler elements are adjacently attached parallel to each other, andsaid plurality of elongated filler elements are positioned to form at least an outer surface of said predetermined shape such that the plurality of six-corner surface tubes and the plurality of elongated filler elements fixedly contain at least one of sensitive and volatile materials. 3. A honeycomb storage device according to claim 1, wherein both ends of each hollow internal tank in each of the plurality of six-corner surface tubes are sealed. 4. A honeycomb storage device according to claim 1, wherein each hollow internal tank in each of the plurality of six-corner surface tubes is formed from at least one of heatproof plastic and heatproof rubber. 5. A honeycomb storage device according to claim 1, further comprising:a plurality of molded five-corner surface tubes, each of the plurality of five-corner surface tubes including a hollow internal tank, and is formed from pre-impregnated fibre-reinforced plastic (FRP prepreg) molded into the five-corner surface with a pentagonal shape in cross-section, surrounding the hollow internal tank, the hollow internal tank being fixedly positioned inside of a corresponding six-corner surface tube and along a longitudinal axis of the corresponding six-corner surface tube, and, the hollow internal tank being formed to contain at least one of sensitive and volatile materials, the FRP prepreg completely filling an internal space of each six-corner surface tube outside of the hollow internal tank, whereinsaid plurality of molded six-corner surface tubes with said plurality of molded five-corner surface tubes are arranged into the predetermined shape such that the tubes are adjacently attached parallel to each other, said plurality of molded five-corner surface tubes being positioned to form at least one of corner portions and end portions of said predetermined shape. 6. A honeycomb storage system for at least one of storing and transporting sensitive or volatile materials, said system comprising:a plurality of honeycomb storage devices, each of the honeycomb storage devices including a plurality of six-corner surface tubes arranged in parallel to each other to form a predetermined shape such that the tubes are longitudinally attached to each other and positioned in a honeycomb structure wherein viewed in cross-section, whereineach of the plurality of six-corner surface tubes includes a hollow internal tank, and is formed from pre-impregnated fibre-reinforced plastic (FRP prepreg) molded into the six-corner surface with a hexagonal shape in cross-section surrounding the hollow internal tank, the hollow internal tank being fixedly positioned inside of a corresponding six-corner surface tube and along a longitudinal axis of the corresponding six-corner surface tube, and the hollow internal tank being formed to contain at least one of sensitive and volatile materials, the FRP prepreg completely filling an internal space of each six-corner surface tube outside of the hollow internal tank,a plurality of elongated filler elements, wherein each of the plurality of elongated filler elements including FRP prepreg molded with a four-corner surface longitudinally along each filler element with a trapezoidal shape in cross-section, the FRP prepreg completely filling an internal space of each elongated filler element,said plurality of molded six-corner surface tubes and said plurality of elongated filler elements are arranged into the predetermined shape such that the plurality of molded six-corner surface tubes and filler elements are adjacently attached parallel to each other,said plurality of elongated filler elements are positioned to form at least an outer surface of said predetermined shape,the plurality of molded six-corner surface tubes and the plurality of elongated filler elements being formed to fixedly contain at least one of sensitive or volatile materials in each of the hollow internal tanks of the plurality of molded six-corner surface tubes, andsaid plurality of honeycomb storage devices are adjacently attached parallel to each other and positioned in a honeycomb structure when viewed in cross-section. 7. A honeycomb storage system according to claim 6, wherein each of said plurality of honeycomb storage devices further include a plurality of molded five-corner surface tubes, each of the plurality of five-corner surface tubes including a hollow internal tank, and is formed from pre-impregnated fibre-reinforced plastic (FRP prepreg) molded into the five-corner surface with a pentagonal shape in cross-section, surrounding the hollow internal tank, the hollow internal tank being fixedly positioned inside of a corresponding six-corner surface tube and along a longitudinal axis of the corresponding six-corner surface tube, and the hollow internal tank being formed to contain at least one of sensitive and volatile materials, the FRP prepreg completely filling an internal space of each six-corner surface tube outside of the hollow internal tank, whereinsaid plurality of molded six-corner surface tubes with said plurality of molded five-corner surface tubes are arranged into the predetermined shape such that the plurality of molded six-corner surface tubes are adjacently attached parallel to each other, said plurality of molded five-corner surface tubes being positioned to form at least one of corner portions and end portions in said plurality of honeycomb storage devices. 8. A honeycomb storage system according to claim 6, wherein said plurality of honeycomb storage devices are adjacently attached parallel to each other in groups of five honeycomb storage devices formed together in an outer rectangular box shape. 9. A honeycomb storage system according to claim 6, wherein said plurality of honeycomb storage devices are adjacently attached parallel to each other and formed together in an outer rectangular shipping container shape to be mounted on a lorry. 10. A honeycomb storage system according to claim 6, wherein said plurality of honeycomb storage devices are adjacently attached parallel to each other and formed together in an outer rectangular shipping container shape to be placed in one of a storage facility and distribution facility.
	abstract	A factor estimating device estimates a factor from a defective result generated in a target system for diagnosis. A factor estimating process is carried out based on causality network recorded in an estimate knowledge recording part, and data on input items corresponding to conditions included in the causality network are obtained. Based on the obtained data, fitness factors are calculated, and certainty factor is obtained for each factor as representing the group of fitness factors corresponding to conditions included in the factor estimating paths. Influence factors showing the degree of influence of obtained data on input items are calculated, and data on input items with high influence factor are obtained.
	description	This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2004-92318, filed on Mar. 26, 2004; the entire contents of which are incorporated herein by reference. 1. Field of the Invention The present invention relates to an apparatus and a method for pressure suppression and decontamination for a reactor container, and more particularly to an apparatus and a method for pressure suppression and decontamination for a reactor container which cools the inside of reactor container and suppresses the pressure rise and the density increase of radioactive substances, at an emergency case such as troubles with the coolant system for the reactor. 2. Description of the Background When a severe trouble such as a trouble with a coolant system takes place in a nuclear reactor, it is possible that the reactor core melts, breaks through the bottom panel board of the reactor pressure vessel and falls into a bottom dry well. At that time, it is possible that a great amount of radioactive substances are generated and non-condensable gas such as hydrogen that is generated through reactions of metal and water fills up in the reactor container and causes a pressure rise in the reactor container. In the worst case, it is possible to exhaust a great amount of radioactive substances into outside air. In order to take a countermeasure for such an event, it is investigated to install a cooling device for dry well either in a bottom dry well or in a top dry well and to cool the gas in the dry well or the cooling pool water for damaged reactor core. (Reference Patents 1 and 2 described below) [Reference Patent 1] Japanese Patent Disclosure (Kokai) 2001-83275 [Reference Patent 2] Japanese Patent Disclosure (Kokai) 2001-215291 It is investigated to cool the dry well or the cooling pool water for the damaged reactor core at an emergency case such as troubles with the coolant system for the reactor, as described in the above. But the technology to suppress effectively the pressure rise in the reactor container and the density increase of the radioactive substances has not yet been developed. Accordingly, an object of this invention is to provide an apparatus and a method for pressure suppression and decontamination for a reactor container which can suppress the pressure rise in the reactor container and can suppress the density increase of radioactive substances, at an emergency case such as troubles with the coolant system for the reactor. According to an aspect of the present invention, there is provided a pressure suppression and decontamination apparatus for a reactor container which is provided with a reactor pressure vessel containing nuclear core fuel and forms a dry well space including, a dry well cooling unit for cooling a gas in the dry well space and for producing a condensate of the gas, a circulation device for leading the gas in the dry well space to the dry well cooling unit, and a sprinkling device for sprinkling the condensate in the dry well space. According to another aspect of this invention, there is provided a pressure suppression and decontamination method for a reactor container which is provided with a reactor pressure vessel containing nuclear core fuel and forms a dry well space, at an emergency case such as troubles with a coolant system of a nuclear reactor including, cooling a gas in the dry well space, producing a condensate of the gas, and sprinkling the condensate in the dry well space. According to the present invention, it is possible to provide an apparatus and a method for pressure suppression and decontamination for a reactor container which can suppress the pressure rise in the reactor container and can suppress the density increase of radioactive substances, at an emergency case such as troubles with the coolant system for the reactor. Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, the embodiments of this invention will be described below. Hereinafter the first and the second embodiments of the present inventions are described by referring to the drawings. FIG. 1 is a cross section drawing showing a reactor container provided with a pressure suppression and decontamination apparatus for a reactor container according to a first embodiment of this invention. In a reactor container 1, a reactor pressure vessel 3 containing a reactor core 2 for holding nuclear fuel is supported by means of pedestals 4. Also, a bottom dry well 5 surrounded by the pedestals 4, a top dry well 6 surrounding the reactor pressure vessel 3 and a pressure suppressing room 9, which is partitioned by a diaphragm floor 7 below the top dry well 6 and contains a pressure suppressing pool water 8 inside are provided in the reactor container 1. The top dry well 6 and the bottom dry well 5 are communicated hydraulically by means of a communicating canal 10. The both dry wells 5 and 6 and a pressure suppressing room 9 are connected each other by a vent tube 11 which extends into the pressure suppressing pool water 8. It is so constructed that the pressure suppressing pool water 8 is lead by a residual heat removing pump 20 in a residual heat removing line 19, and after the heat removal at a residual heat removing heat exchanger 21, the pressure suppressing pool water 8 is sprinkled from a spray header 22 in the top dry well 5, to form a spray cooling system. This cooling system is used for cooling the reactor container 1 at a high temperature and at a high pressure. Also, in the reactor container 1, a plurality of dry well cooling units 15 are installed. A fan 16 is connected to each of the dry well cooling units 15. The fan 16 is a device for circulating the gas inside the dry wells 5 and 6 into dry well cooling unit 15. The dry well cooling unit 15 is composed of a casing 14 and a cooling coil 13 involved therein. In the piping of the cooling coil 13, cooling water is flown, and a gas 40 in the bottom and top dry wells 5 and 6 is lead into the casing 14. In details, the inner pressure of the casing 14 is lowered using a fan 16, and thus a flow of the gas is induced by the pressure difference between inside and outside of the casing 14. The gas 40 induced into the casing 14 passes through the outside of the piping of the cooling coil 13 and is cooled. The cooled gas 40 is transferred to everywhere in the bottom and top dry well 5 and 6 through a duct 17 and a damper 18. Also, the vapor involved in the gas 40 introduced into the casing 14 containing the cooling coil 13 is condensed by flowing water in the cooling coil 13 of the dry well cooling unit 15. And then, in order to compensate the pressure drop due to the condensation, the gas 40 in the reactor container 1 is induced into the casing 14 to reduce the pressure in the reactor container 1. As described in the above, the vapor of which heat is removed at the dry well cooling unit 15 is condensed, and a condensate 41 is lead to a drain sump at the bottom of the bottom dry well 5 through a drain pipe 23. A power source 36 which supplies the power to the fan 16 connected to the dry well cooling unit 15 is connected to an electrical system, which is operative only at the normal operation of the nuclear reactor and stops automatically at an emergency case. Furthermore, according to the present embodiment, a changeover device 24 and a sprinkling device 25 are provided to the drain pipe 23 which discharges the condensate 41 produced at the dry well cooling unit 15. The condensate 41 produced by the condensation of the vapor involved in the gas 40 in the bottom and top dry wells 5 and 6 is sprinkled in the top dry well 6. FIG. 2 is a cross section showing a main portion of the pressure suppression and decontamination apparatus for the reactor container according to this embodiment. As shown in the drawing, the drain pipe 23, which discharges the condensate 41 from the dry well cooling unit 15 installed as one of the cooling installations in the reactor container 1, is provided with the changeover device 24, which is connected to the cooling unit 15 via abutting connection 42, and the sprinkling device 25. In this connection, the changeover device 24 has a function that it flows the condensate 14 from the dry well cooling unit 15 to the drain pipe 23 normally and flows to the sprinkling device 25 at an emergency case. The sprinkling device 25 scatters the condensate 41 switched by the changeover device 24 as liquid drops in the dry well space. By this, the surface area of the sprinkled condensate 41 becomes large and the removing efficiency of the radioactive substances is increased. FIG. 3 is a detailed cross section of the changeover device 24. The changeover device 24 is provided with a changeover panel 26 which rotates almost 90 degrees and a high temperature melting and adhesive metal 27, which sticks the changeover panel 26 to the change over mechanism and melts at a high temperature. By means of this construction, the high temperature melting and adhesive metal 27 melts when the temperature becomes high at an emergency case, and the changeover panel 26 closes the drain pipe 23, and thereby the flow of the condensate 41 is changed over to the sprinkling device 25. FIG. 4 is a cross section of another example of the changeover device 24. The changeover device 24 is operated by the driving force at the opening and closing of the damper 18 mounted in the duct 17 shown in FIG. 1. In detail, the changeover panel 26 is connected with the outlet of the damper 18 mechanically by means of a spring or the like, and opens by utilizing the driving force of the closing damper 18. At an emergency case, the changeover panel 26 closes the drain pipe 23 and changes over the flow of the condensate 41 to the sprinkling device 25. FIG. 5 is a drawing showing the details of the sprinkling device 25. Here, FIG. 5(a) shows a construction that a plurality of the sprinkling holes 28 are provided at the end of the outlet of the condensate 41, FIG. 5(b) shows a construction that a collision plate 29 is provided to which the condensate collides at the end of the outlet of the condensate 41, and FIG. 5(c) shows a construction that a sprinkling blade 30, which scatters the condensate 41, is provided at the end of the outlet of the condensate 41. By means of these constructions, the condensate 41 can be scattered as liquid drops into the dry well atmosphere. FIG. 6 is a drawing showing a modification of the embodiment of the present invention. In FIG. 6, a mechanism for exhausting in the casing 14 of the dry well cooling unit 15 and the sprinkling device 25 are linked. In this modification, a rotating mechanism 35 for rotating by means of the flow of the condensate 41 in the sprinkling device 25 is provided. A shut-off plate 32 and an exhaust fan 33 are provided at the casing 14 of the dry well cooling unit 15. Further, the rotating mechanism 35 and the exhaust fan 33 are connected by means of a connecting shaft 34. According to this modification, the non-condensed gas accumulated in the casing 14 can be exhausted to the outside, and thereby the condensation of the vapor can be promoted. The shut-off plate 32 closes during an operation of the circulation device and opens during a stoppage of the circulation device. In other words, shut-off plate is configured to be in a closed position during operation of said circulation device and configured to be in an open position during stoppage of said circulation device. If a case of the loss of coolant accident (LOCA) that the coolant flows out of the inside of the reactor pressure vessel 3 by any reason might occur, a great amount of the mixture of a vapor and a water of high temperature is exhausted into the bottom and top dry wells 5 and 6. This mixture is lead to the pressure suppressing pool water 8 in the pressure suppressing room 9 through the vent pipe 11. When the accident becomes to a severe accident, it is possible that the reactor core 2 in the reactor pressure vessel 3 melts, penetrates the bottom panel board of the reactor pressure vessel 3 and falls into the bottom dry well 5. And then, it is possible that non-condensable gas such as hydrogen produced by the reaction of the large amount of radioactive substances, metal and water is generated in the reactor container 1, and a pressure rise in the reactor container 1 is caused. Also, at this moment the power source 36 is shut off automatically by the safety reason. Thus, many devices including the fan 16 are stopped. On the other hand, the vapor contained in the gas 40 in the casing 14 is condensed by the cooling coil 13 of the dry well cooling unit 15, and the condensate is produced. In this connection, according to the embodiment of the present invention, the condensate 41 from the dry well cooling unit 15 is sprinkled into the dry well atmosphere by the changeover device 24 and the sprinkling device 25. Therefore, the radioactive substances in the dry well atmosphere are removed by the liquid drops. Thus the density of the radioactive substances in the dry well atmosphere is reduced. As described in the above, according to the embodiment of the present invention, the fan 16 as the circulation device that leads the gas 40 from the dry well space into the dry well cooling unit 15 and the sprinkling device 25 which sprinkles the condensate 41 produced by the condensation of the vapor involved in the gas 40 are provided. Thus, the radioactive substances in the reactor container 1 can be removed. Furthermore, it is possible to keep the performance of removing the heat in the dry well cooling unit 15. Therefore, even at an emergency case, it is possible to suppress the pressure in the reactor container 1 and to suppress the density of the radioactive substances. FIG. 7 is a cross section drawing showing a reactor container provided with a pressure suppression and decontamination apparatus for a reactor container according to a second embodiment of this invention. As shown in FIG. 7, this embodiment provides the construction that the change over device 24 and the sprinkling device 25 are provided in the bottom dry well 5. The respective constructions of the dry well cooling unit 15, the changeover device 24 and the sprinkling device 25 are the same as shown in the first embodiment. According to this embodiment, the radioactive substances can be removed efficiently at a range where the density of the radioactive substances is high. Meantime, it should be understood that the present invention is not limited to the embodiments described in the above. For example, when the embodiment of the present invention is described, a boiling water reactor (BWR) is taken as an example as shown in FIG. 1 and FIG. 7. But this invention can be applied also to pressurized water reactors (PWR). Also, the dry well cooling unit 15 may be provided outside of the reactor container 1 and the intake port and the discharge port may be provided in the reactor container 1. Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.
051986787	description	The polymerization device for treating plastic dental elements has an irradiation chamber 1 with a light conductor 2, a hand-held polymerization unit 3 serving as a radiation source unit, and a support frame 4, with the aid of which the other components of the polymerization device are fixed in their positions relative to one another. The support frame 4 has a support plate 5, a first support 6 and a second support 7, both of which stand approximately vertically on the support plate 5 of the support frame 4. The hand-held polymerization unit 3 has a housing, with the light source disposed in the front and the fan accommodated in the back. The back portion of the housing is bent somewhat at an angle, so as not to direct the air flow produced by the fan onto the arm of the doctor manipulating the hand-held polymerization unit. A socket 8 that serves to receive the light conductor 2 and its external sheathing is mounted on the front of the housing. A screw 10 for screwing the housing together and a trumpet-shaped cable guide 11 to protect against bending are mounted laterally on the front of the housing. An activation switch 12 is located on the socket 8 of the hand-held polymerization unit 3 in a position such that it can be actuated with the thumb if the socket 8 is held with the index finger. The hand-held polymerization unit 3 is thrust with its socket part through an opening 13 of the first support 6 onto the external sheathing of the light conductor 2. The opening 13 corresponds to the cross section of the front part of the housing. The first support 6 also has a slit 14 extending through to the outside of the first support 6. The protrusion 9 located on the housing protrudes into this slit 14, so that the hand-held polymerization unit 3 is supported in a torsionally fixed manner, that is, in a manner fixed against relative rotation. The slit 14 is mounted at an angle of approximately 45.degree. to the support plate 5, such that the air outlet opening 15 of the hand-held polymerization unit 3 points away from the body of the doctor using the polymerization device, and the activation switch 12 is located on a side remote from the support plate 5. The light conductor 2, located in the socket 8 along with its external sheathing, protrudes through an opening in the second support 7. The irradiation chamber 1, which has an opening on one side for receiving the light conductor 2 and its external sheathing, is pressed by this opening onto the end of the light conductor 2 and its external sheathing; the external sheathing has an encompassing bead on one end, which locks into place in the opening of the irradiation chamber 1. A fixed housing part 16 of the irradiation chamber 1 then rests on the second support 7. The base of the irradiation chamber 1 has two lateral ribs on the bottom that partly enclose the outer contour of the support plate 5. To make it possible to equip the irradiation chamber 1 appropriately, the upper housing portion 18 of the irradiation chamber 1 is supported on a pivot shaft 19. The pivot shaft 19 is located near the part of the fixed housing portion 16 that rests on the second support 7. A window 20 by which the polymerization process can be observed is let into the top of the upper housing portion 18. The openings in the first support 6 and second support 7 are mounted such that the axis of the light conductor 2 extends parallel to the support plate 5. The entire support frame 4 is made from acrylic glass. Holes 21 by which the polymerization device can be secured to a table or a wall are located in the support plate 5. Various changes and modifications may be made, and features described in connection with the embodiment may be used in any combination, within the scope of the inventive concept.
	summary
048266485	summary	BACKGROUND OF THE INVENTION 1. Field of the Art The invention relates to neutron absorbing bars for liquid cooled nuclear reactors of the type having a cluster of vertical parallel neutron absorbing rods fixed to arms of a spider having a central pommel connectable to a vertical moving mechanism and a damping device in the pommel. It is particularly suitable for use in pressurized water cooled and moderated reactors. 2. Prior Art Neutron absorbing bars for nuclear reactors include rods which contain a neutron poison for controlling the reactivity in the core of the reactor. They are inserted into the core to a variable degree. To cause an emergency shutdown of the reactor, all control bars are simultaneously lowered into the core by dropping them so that they enter the core under the action of their own weight. To damp the shock when the pommel abuts against the upper core plate of the reactor or against the upper end piece of a respective fuel assembly, the provision of a shock damper has already been proposed. A control bar described in European Patent No. 159 509 has a damping device consisting of a cylinder formed in the pommel and slidably receiving a piston urged downwardly by resilient means contained in the cylinder. From the moment when the piston abuts the upper core plate, continued downward movement is opposed by the compression of the resilient means and by the pressure loss undergone by the liquid which flows out of the cylinder between the wall thereof and the piston. Such a damping device has, however, only a limited effect: the damping effect due to the pressure loss does not change substantially during movement of the piston and only the increasing stiffness of the spring provides progresivity. Furthermore, the device in the pommel interferes with the flow of cooling liquid. Such shortcomings could be accepted for bars whose rods contain a neutron poison in coherent form and which do not require substantial cooling. It is no longer acceptable when the bars contain other compounds of limited resistance, and particularly when the rods of the bar contain a material used for varying the energy spectrum of the neutrons in the core. This material often consists of fertile material pellets (depleted uranium oxide, and/or thorium oxide for example) which do not withstand shocks. SUMMARY OF THE INVENTION It is an object of the invention to provide a neutron absorbing bar having a damping device reducing the shock impressed to the bar when it engages the core plate and allowing satisfactory cooling, particularly of the rods, under all operating conditions. It is to be kept in mind that, contrary to the rods containing a poison having parasitic absorption, the rods containing fertile material must be cooled by a flow of cooling liquid. To this end, there is provided a bar of the above defined type wherein the cylinder and piston are formed so that the leak cross-sectional area offered to the liquid driven out of the cylinder by the piston decreases gradually during penetration of the latter from its position of maximum extension, and the piston has a hydromechanical damper for damping the impact when the bar initially contacts the upper core plate or fuel assembly for reducing the speed of the piston.
044143397	summary	BACKGROUND OF THE INVENTION This invention relates to a composition for suppressing electromagnetic radiation and, particularly, for reducing the reflection of microwave energy. The use of materials for absorbing electromagnetic radiation is wide spread in the coating of (1) military devices which are required to avoid or minimize detection by radar, (2) appliances that employ microwave radiation, and (3) reflectors of ships, airplanes, building and bridges to reduce reflection that often causes navigational errors. Many materials including natural ones and synthetic ones are known for their ability to surpress electromagnetic radiation in the microwave frequency range. This ability to suppress electromagnetic radiation enables the absorbing material to dissipate electromagnetic energy within the material, thereby reducing the reflection of microwaves. Of the various absorbing materials, the artificial dielectrics are the most commonly employed. Artificial dielectrics are generally formed by dispersing a magnetic powder or other natural absorber in a dielectric material, such as plastics including thermoplastics and thermosets, ceramics, waxes and the like. The artificial dielectrics which have been formed by loading the aforementioned dielectric binders with magnetic metals, semi-conductors, ferromagnetic oxides or ferrites have very desirable magnetic and dielectric properties. The use of solid ferrites, i.e., ferromagnetic ferrites formed of ferric oxide and other bivalent metal oxides, as sheet materials for reflecting surfaces and objects to suppress or substantially reduce the reflection of electromagnetic energy offers many advantages. It has been found that mixed ferrites often provide good absorptive materials over a wide range of microwave frequencies. In addition, ferrites in the form of solid coatings display the higher permeabilities which are required for broad band operation. Such solid ferrite coatings are capable of higher permeabilities than those exhibited by the ferrite powders since the magnetic properties of ferrite decline appreciably by grinding it into powder form. Thus, it is found that ferrites that are both non-conductive and ferromagnetic provide within a single composition the potentially optimum dielectric and magnetic properties. Unfortunately, it is found that, in the conventional absorptive coatings that contain ferrites, substantial quantities of the heavy ferrites is required in order to achieve the desired absorptive capability. The resulting dense coatings of such conventional absorbers are generally undesirable because they are heavy and difficult to fabricate. In view of the aforementioned deficiencies of the prior art materials for absorbing electromagnetic radiation, it is highly desirable to provide a lightweight absorptive material that can be readily fabricated into any shape or applied as a coating to any of a variety of substrates which coatings contain relatively low concentrations of the heavy magnetic particles needed for absorption. SUMMARY OF THE INVENTION The present invention is such a low density ELM absorption composition which exhibits high efficiency in the absorption of electromagnetic radiation, particularly at microwave frequencies. Such composition (hereinafter called ELM compositions) comprises (1) a dielectric material (hereinafter called dielectric matrix) having dispersed therein (2) a colloidal-size particulate of a material capable of absorbing electromagnetic radiation (hereinafter called ELM absorber) and (3) a particulate of a metal-containing material capable of providing increased attenuation of electromagnetic radiation (hereinafter called ELM attenuator). The concentration of ELM absorber in the ELM composition is advantageously sufficient to provide a magnetic loss tangent greater than 0.05 at a frequency of 2 gegahertz (gHz) and a composition thickness of 2 centimeters (cm). The concentration of ELM attenuator is sufficient to provide the ELM composition with an attenuation of greater than 0.5 decibels per centimeter (dB/cm) under the aforementioned conditions. For the purposes of this invention, a low density ELM composition has a density less than 6 grams per cubic centimeter (g/cm.sup.3). Surprisingly, the low density ELM composition of the present invention exhibits dissipative properties higher than would be expected at the concentrations of ELM absorber being employed. In another aspect, this invention is a stable fluid dispersion of the aforementioned ELM attenuator and colloidal-sized particles of the dielectric matrix containing colloidal or sub-colloidal particles of the ELM absorber. Surprisingly, such a dispersion can be applied as a coating and dried to form a continuous film wherein the particles of the ELM absorber are maintained in an essentially discrete spaced apart relationship by the dielectric matrix. Preferably, particles of the ELM attenuator are also substantially maintained in an essentially discrete spaced apart relation by the dielectric matrix. The ELM composition of this invention is particularly effective as an electromagnetic radiation absorber in such applications as paints and coatings to be used for reflection for metal structures such as towers, bridges, ships, etc.; microwave camouflage and radar camouflage; coatings for appliances wherein microwave radiation absorption is desired, such as in microwave ovens and microwave browning devices; applications related to the transport of solar energy from space satellites; and the like. This ELM composition is also well suited for molding shaped articles and for fabrication into foams and fibers. DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS The low density ELM composition of the present invention has a density, an attenuation and a magnetic loss tangent as defined hereinbefore. Preferred compositions have (1) densities in the range from about 1.2 to about 5, most preferably from about 1.5 to about 3, g/cm.sup.3 ; (2) magnetic loss tangent greater than 0.1, most preferably greater than 0.2 under the conditions specified hereinbefore; and (3) attenuation greater than 1 dB/cm, most preferably greater than about 2 dB/cm. The ELM compositions comprises three essential components: (1) a dielectric solid matrix acting as the continuous phase for the composition, (2) a particulate ELM absorber that is maintained in an essentially discrete, spaced apart relationship by the matrix and (3) a particulate ELM attenuator. In preferred ELM compositions, the ELM attentuator is also essentially totally dispersed in the dielectric matrix. The dielectric matrix is suitably any normally solid material capable of serving as an insulating matrix (binder) for the ELM absorber. Preferably, it has an electrical resistivity greater than 10.sup.6 ohms per centimeter (ohms/cm), more preferably greater than about 10.sup.10 ohms/cm, most preferably from about 10.sup.15 to 10.sup.20 ohms/cm. Examples of such suitable dielectrics include glass, ceramics, waxes, plastics, including thermoplastics and thermosets, rubber polymers and the like, with the synthetic plastics being preferred. Of the synthetic plastics, preferred are polymers that are water-insoluble and are prepared from hydrophobic monomers that are essentially water-immiscible, i.e., the monomer forms a separate phase when 5 grams of the monomer is mixed with 100 grams of water. Such water immiscible will polymerize under emulsion polymerization conditions to form a water-insoluble polymer which will exist in the form of a stable aqueous colloidal dispersion, usually with the aid of suitable surface active agents. The ELM absorber is a material (1) which absorbs electromagnetic radiation having frequencies in the range from about 0.3 to about 20 gHz and (2) which is in the form of a colloidal or sub-colloidal size particulate. Preferred ELM absorbers can be further characterized as paramagnetic or superparamagnetic due to their small size. Examples of such materials are compounds of magnetic metals such as ferromagnetic oxides or ferrites, e.g., Fe.sub.3 O.sub.4, as well as ferromagnetic ferrites formed of ferric oxide and various bivalent metal oxides such as metal oxides of nickel, zinc and manganese; magnetic metals such as iron, cobalt and nickel and their alloys; and other known ELM absorbing materials such as carbon black, graphite and the like. The ELM absorber generally contains particles having a maximum dimension less than about 1 micrometer (.mu.m), preferably in the range from about 0.01 to about 0.7 .mu.m. Of these materials, the magnetic metallic compounds are preferred, with Fe.sub.3 O.sub.4 being most preferred. The ELM attenuator is preferably a ferromagnetic material which is capable of providing microwave attenuation as described hereinbefore. The ELM attenuator is in the form of particles having a dimension greater than 1 .mu.m, preferably in the range from about 1.5 to about 100 .mu.m, most preferably from about 2 to about 75 .mu.m. Examples of such attenuating materials are iron, cobalt, nickel and other ferromagnetic metals as well as alloys of such metals. Of these materials, metallic iron is preferred, with carbonyl iron being most preferred. It is understood, however, that in addition to carbonyl iron, metallic iron made by other procedures such as electrolytic iron, reduced iron and atomized iron are preferred. In the preparation of the low density, ELM absorbing compositions of this invention, it is advantageous to disperse the ELM absorber into the dielectric matrix such that dielectric matrix forms a continuous phase that maintains the particles of ELM absorber in an essentially discrete, spaced apart relationship. Any of a variety of conventional blending procedures for incorporating a colloidal or sub-colloidal particulate into dielectric binders are suitably employed for this purpose. Preferably, however, the dielectric matrix having the ELM absorber dispersed therein (hereinafter called dielectric/absorber), is prepared by initially forming an aqueous dispersion of the ELM absorber by contacting colloidal or sub-colloidal particles of said absorber with an aqueous solution of a water-soluble surfactant or emulsifier, thereby forming the dispersion which contains from about 5 to about 70 weight percent of the absorber particles. Examples of preferred aqueous dispersions of ELM absorbers are the so-called ferrofluids such as disclosed in the U.S. Pat. No. 3,981,844, preferably those having an average particle diameter in the range from about 0.05 to about 0.1 micrometer. Preferably, such fluids are aqueous dispersions of the magnetic metals which are stabilized by the presence of surfactants, emulsifiers and/or chemical dispersants as described hereinafter. Typically, suitable surface active agents, dispersants or emulsifiers include salts of fatty acids such as potassium oleate, metal alkyl sulfates such as sodium lauryl sulfate, salts of alkyl aryl sulfonic acids such as sodium dodecylbenzene sulfonate, polysoaps such as sodium polyacrylate and alkali metal salts of methyl methacrylate/2-sulfoethyl methacrylate copolymers and other sulfoalkyl acrylate copolymers, and other anionic surfactants such as the dihexyl ester of sodium sulfosuccinic acid; nonionic surfactants such as the nonionic condensates of ethylene oxide with propylene oxide, ethylene glycol and/or propylene glycol; and cationic surfactants such as alkylamine-guanidine polyoxyethanols, as well as a wide variety of micelle generating substances described by D. C. Blackley in Emulsion Polymerization, Wiley and Sons, Chapter 7 (1975) and other surfactants listed in McCutcheon's Detergents and Emulsifiers, 1980 Annual North Americal Edition, McCutcheon, Inc., Morristown, N.J. Also included among the suitable surfactants are the surface active polymers (often called polysoaps), e.g., those described in U.S. Pat. No. 3,965,032. Of the suitable surfactants, the anionic varieties such as the potassium salts of functionalized oligomers, e.g., Polywet varieties sold by Uniroyal Chemical, are preferred. Such surface active agents or emulsifiers are employed in amounts sufficient to provide a stable dispersion of the ELM absorber in water. Preferably, such surface active agents are employed in concentrations in the range from about 0.2 to about 10, most preferably from about 1 to about 6, weight percent based on the aqueous phase. Particularly desirable processes for forming such aqueous colloidal dispersions of the ELM absorber are described in U.S. Pat. Nos. 3,826,667; 3,981,844; 3,843,540 and Industrial Engineering Production and Research Development, Vol. 19, 147-151 (1980). The aqueous dispersion of the ELM absorber is then combined with the water-immiscible monomer as described herein to form the desired emulsion by normal mixing procedures, for example, by passing both the dispersion and monomer through a high shear mixing device such as a Waring blender, homogenizer or ultrasonic mixer. Alternatively and preferably, the monomer is added continuously to the aqueous dispersion of the ELM absorber during the polymerization. Advantageously, the monomer is in the form of an aqueous emulsion of the monomer which emulsion is maintained by a water-soluble monomer and/or a water-soluble emulsifier such as described hereinbefore. As another alternative, the aqueous emulsion of the ELM absorber and water-immiscible monomer can be prepared by adding colloidal or subcolloidal particles of the ELM absorber to an existing aqueous emulsion of monomer. In such instances, it is often desirable to add additional emulsifier or surfactant to the emulsion prior to or simultaneous with the addition of the particles of the ELM absorber. In the emulsion of the ELM absorber and water-immiscible monomer in water, the aqueous phase is present in a proportion sufficient to be the continuous phase of the emulsion. The ELM absorber is present in proportions sufficient to provide the dielectric/absorber particulate with the desired dissipative properties. The water-immiscible monomer is present in proportion sufficient to enclose or encapsulate the ELM absorber when polymerized. The emulsifier and/or surface active agent is present to provide an aqueous colloidal emulsion which is sufficiently stable to be subjected to emulsion polymerization conditions. Preferably, the emulsion contains from about 0.1 to about 25 weight percent of ELM absorber, from about 1 to about 30 weight percent of monomer and a remaining amount of the aqueous phase including emulsifier (surfactant), catalyst and the like. Examples of suitable water-immiscible monomers that can be employed to prepare the aforementioned dielectric/absorber include monovinylidene aromatic monomers such as styrene, vinyl toluene, t-butyl styrene, chlorostyrene, vinylbenzyl chloride and vinyl pyridene; alkyl esters of .alpha.,.beta.-ethylenically unsaturated acids such as ethyl acrylate, methyl methacrylate, butyl acrylate and 2-ethylhexyl acrylate; unsaturated esters of saturated carboxylic acids such as vinyl acetate, unsaturated halides such as vinyl chloride and vinylidene chloride; unsaturated nitriles such as acrylonitrile; dienes such as butadiene and isoprene; and the like. Of these monomers, the monovinylidene aromatics such as styrene and the alkyl acrylates such as butyl acrylate are preferred. In addition to the aforementioned water-immiscible monomer, relatively minor portions, e.g., less than 10, preferably less than 5, weight percent based on total monomer component, of a water-soluble monomer such as an ethylenically unsaturated carboxylic acid or its salt such as acrylic acid or sodium acrylate; methacrylic acid, itaconic acid and maleic acid; an ethylenically unsaturated carboxamide such as acrylamide; vinyl pyrrolidone; hydroxyalkyl acrylates and methacrylates such as hydroxyethyl acrylate, hydroxypropyl acrylate and hydroxyethyl methacrylate; aminoalkyl esters of unsaturated acids such as 2-aminoethyl methacrylate; epoxy functional monomers such as glycidyl methacrylate; sulfoalkyl esters of unsaturated acids such as 2-sulfoethyl methacrylate; ethylenically unsaturated quaternary ammonium compounds such as vinylbenzyl trimethyl ammonium chloride may be employed. It is critical in the practice of this preferred embodiment, that such water-soluble monomers not be employed in amounts sufficient to render the resulting polymer soluble in water. Particularly effective monomer recipes for the practice of this invention are those containing from about 20 to about 90 weight percent of styrene, from about 10 to about 80 weight percent of alkyl acrylate such as butyl acrylate and from about 0.01 to about 2 weight percent of the unsaturated carboxylic acids such as acrylic acid, with said weight percentages being based on the weight of total monomers. The emulsion polymerization conditions employed in the practice of this preferred embodiment of the invention are generally those of conventional free-radical type polymerization carried out in the presence of a radical initiator such as a peroxygen compound, an azo catalyst, ultraviolet light and the like. Preferably, such polymerization is carried out in the presence of a water-soluble peroxygen compound at temperatures in the range from about 50.degree. to about 90.degree. C. The emulsion is generally agitated during the polymerization period in order to maintain adequate feed transfer. The concentration of catalyst is normally in the range from about 0.005 to about 8, preferably from about 0.01 to about 5, weight percent based on total momomer. Examples of suitable catalysts include inorganic persulfate compounds such as sodium persulfate, potassium persulfate, ammonium persulfate; peroxides such as hydrogen peroxide, t-butyl hydroperoxide, dibenzol peroxide and dilauroyl peroxide; azo catalysts such as azobisisobutyronitrile, and other common free-radical generating compounds. Also suitable are various forms of free-radical generating radiation means such as ultraviolet radiation, electron beam radiation and gamma radiation. Alternatively, a redox catalyst composition can be employed wherein the polymerization temperature ranges from about 25.degree. to about 80.degree. C. Exemplary redox catalyst compositions include a peroxygen compound as described hereinbefore, preferably potassium persulfate or t-butyl hydroperoxide and a reducing component such as sodium metabisulfite and sodium formaldehyde hydrosulfite. It is also suitable to employ various chain transfer agents such as mercaptans, e.g., dodecyl mercaptan; dialkyl xanthogen disulfides; diaryl disulfides and others listed in Blackley, supra, Chapter 8 in concentrations as described therein. Following emulsion polymerization, the resulting aqueous dispersion of the particles of dielectric/ELM absorber can be withdrawn from the polymerization vessel and (1) the dispersion is employed as is or (2) the unreacted monomer and other volatiles are removed to form a concentrated dispersion and then used as a paint base for the ELM composition or (3) the dielectric/ELM absorber particulate can be separated from the aqueous continuous phase of the dispersion by conventional means such as spray drying or drying under vacuum. If dried, the dielectric/ELM absorber particulate preferably contains from about 10 to about 80, most preferably from about 15 to about 70, weight percent of the ELM absorber and from about 90 to about 20, most preferably from about 85 to about 30, weight percent of dielectric matrix polymer. In this preferred embodiment, the dielectric/ELM absorber in the form of an aqueous dispersion or a dry colloidal-size particulate is then combined with the ELM attenuator to provide the desired low density, ELM absorbing composition. Preferably, the ELM attenuator (particulate) is dispersed as an aqueous dispersion of the dielectric/ELM absorber, thereby forming a coating compositions which can be applied to any substrate as desired and dried to a continuous coating capable of absorbing ELM radiation. Alternatively, the ELM attenuator may be encapsulated in a suitably dielectric material as defined hereinbefore prior to combination with the dielectric/ELM absorber. In this alternative embodiment, the ELM attenuator and dielectric/ELM absorber may be in the form of aqueous dispersions and/or in the form of dry powders when combined. In dry form, the resulting low density, ELM compositions can be fabricated into an article of desired shape by conventional fabrication techniques such as injection or compression molding, extrusion and the like. Alternatively, the ELM composition in the form of a dry powder is dispersed in a nonaqueous liquid and employed as desired, e.g., as a paint base or base for other coating formulations. Preferred low density, ELM absorbing compositions that employ colloidal-size Fe.sub.3 O.sub.4 as the ELM absorber and carbonyl iron as the ELM attenuator have an ELM absorber:ELM attenuator weight ratio from about 90:10 to about 40:60, most preferably from about 80:20 to about 55:45. In the preferred ELM compositions, the weight ratio of the sum of ELM absorber and ELM attenuator to the dielectric matrix is from about 85:15 to about 10:90, most preferably from about 70:30 to about 55:45. In addition to the foregoing critical components, these compositions optionally contain other ingredients such as stabilizers, pigments, fillers, blowing agents, corrosion inhibitors and other additives commonly employed in ELM absorbing compositions.
051397331	description	DESCRIPTION OF PREFERRED EMBODIMENT FIG. 1 illustrates a transfer cupboard for a fuel assembly of a nuclear reactor 1. The cupboard 1 is constituted by a cylindrical body 2 comprising, in its central part and along its axis, a bore 3 passing through the body over its entire length. The cupboard body consists of a solid steel piece of great thickness in the radial direction and of great length. As regards a fuel assembly for a fast-neutron reactor, greater than 4 m in length and with a hexagonal cross-section, the side of which has a length of 125 mm, the body 2 of the cupboard possesses an outside diameter of 1.30 m, a central bore 0.30 m in diameter an a length of the order of 6 m. The cupboard body therefore has a wall thickness of 0.50 m; its total mass is about 55 tons. In FIG. 1, the fuel assembly 4 is shown in its transport position within a central receptacle 3 of the cupboard body. The assembly 4 occupies only some of the length of the receptacle 3; in the upper part of the receptacle 3 is arranged the grab 7 of the lifting device 6 for the assembly. The lower part of the body 2 is connected to the support 8 of a motorized cupboard valve 9 making it possible to effect the opening or sealing closure of the end of the bore 3 in its lower part opening out at the end of the body 2. The support 8 of the cupboard valve 9 is adapted to be connected to the support 10 of a well valve 11 making it possible to effect the opening or sealing closure of a passage well, for example a passage leading through a slab covering the reactor vessel filled with liquid sodium and containing the reactor core. When the valves 9 and 11 are superposed and open, the fuel assembly 4 can be changed from a position submerged in the liquid sodium to its transfer position within the cupboard 1 by the use of the lifting device 6. The lifting device 6 comprises four winches 12 arranged at 90.degree. relative to one another about the body 2 of the cupboard. Wound on each of the winches 12 is one end of a cable 13 which, by means of return and lifting pulleys accommodated in the upper part of the body of the cupboard 1, makes it possible to obtain the displacement of the grab 7 which has fingers for catching the assembly 4 on the inside of the bore 3 and in its axial extension. Order to ensure its introduction into or order to ensure its introduction into the cupboard or, on its extraction from the cupboard. The grab 7 comprises a hollow part of cylindrical shape carrying the fingers for catching the assembly, which is fixed in its upper part to a lifting and guiding assembly 14 carrying the lifting pulleys and pierced radially with channels communicating with the central bore of the grab 7. When the fuel assembly 4 is in its transfer position within the cupboard 1, as shown in FIG. 1, the assembly 14 is located in the upper part of the bore 3 of the cupboard body, in a specific position in relation to the solid body 2 of the cupboard. Referring to FIGS. 1 and 2, a circuit 15 for the circulation and purification of the cooling gas for the assembly 4 arranged in the receptacle 3 of the body 2 of the cupboard will now be described. The cooling circuit 15 comprises a main channel 16 machined in the body 2 of the cupboard, a device 18 for circulating the gas in the circuit, a device 17 for purifying the circulating gas, and two channels 20 and 21 connecting the main channel 16 and the receptacle 3 for the assembly 4, by means of which the circuit 15 is closed again. The cooling apparatus for the assembly comprises four circuits identical to the circuit 15 and arranged in positions located at 90.degree. relative to one another about the axis of the body 2 and of the receptacle 3 of the cupboard. The main channel 16 of each of the cooling circuits extends in a substantially axial direction parallel to the axis of the receptacle 3 and of the solid cylindrical body 2 of the cupboard 1, over a substantial part of the axial length of the body 2. The channel 16 has a substantially smaller diameter than receptacle 3. For example, in the present case, the diameter of the main channel 16 is 50 mm. The upper part of main channel 16 opens into a receptacle 22 which is machined in the body 2 of the cupboard and the diameter of which is substantially larger than the diameter of the channel 16. The gas purification device 17 consisting of a separator of the cyclone type is arranged in the receptacle 22 in such a way that the upper end of the main channel 16 opening into the receptacle 22 is in communication with the inlet of the separator. The end of the receptacle 22 opposite the inlet end of the separator 17 is in communication with a blower 18 constituting the means for circulating the cooling gas in the circuit formed within the body of the cupboard. The blower 18 is in communication via its suction port with the outlet of the cyclone separator 17 and ensures that an inert cooling gas is delivered and blown to the periphery of the receptacle 22 communicating, by way of the upper connecting channel 20, with the upper part of the receptacle 3 for the assembly 4. As represented schematically by the arrows 24 in FIG. 2, the cooling gas, which may be an inert gas, such as argon, is delivered by the blower 18 into the channel 20 and then, by means of the part 14, into the central bore of the grab 7. The blowing of cooling gas into contact with the assembly 4 and in the longitudinal direction of this assembly is carried out by way of the central bore of the grab 7. The inert gas, which has circulated in contact with the assembly and over its entire length and which ensures the cooling of the assembly, is returned to the lower part of the main channel 16 by way of the connecting channel 21. The cooling gas, which has circulated in contact with the assembly which it cools, has heated up, its outlet temperature depending on the energy emitted by the fuel assembly 4 and on the gas flow circulating in the cooling circuit. Furthermore, the cooling gas circulating in contact with the assembly carries with it sodium aerosols and residual sodium droplets which are retained by the prism-shaped envelope and fuel elements or needles of the assembly at the moment when this assembly is extracted from the liquid sodium, when it is being introduced into the cupboard 1. The cooling gas arriving at the lower part of the main channel 16 is therefore hot and laden with sodium droplets and sodium gas. The relatively high circulation rate of the gas determined by the blower 18 and the small diameter of the channel 16 generates a turbulent flow of the cooling gas within the channel 16, this circulation occurring in the vertical direction and from the bottom upwards. As a result of its turbulent flow in the channel 16 over a substantial part of the height of the body 2 of the cupboard, the gas cools very quickly, giving off its heat to the metal mass of the body 2. The body 2 of the cupboard is surrounded by a tubular screen or thermal shield 26 which ensures the cooling of the cupboard body 2 by thermosiphon, cooling air circulating between the body 2 and shield 26 as a result of the convection currents. The heat transmitted to the solid body 2 of the cupboard by the cooling gas and by the fuel assembly is therefore eliminated by natural circulation. The cooled gas carrying sodium aerosols and droplets in suspension arrives at the upper part of the main channel 16 in the receptacle 22 and enters the cyclone separator 17. The cooling gas circulates in the separator 17 in a swirling manner, as indicated schematically by the arrow 25, in such a way that the sodium droplets are separated from the cooling gas and collect in the lower part of the separator, before flowing by gravity into a vertical channel 28 machined inside the body 2 of the cupboard. The upper part of channel 28 opens into the receptacle 22 and the lower part into a sodium collection tank 30 arranged in the support 8 of the valve 9 for closing the receptacle 3 of the cupboard. The gas sucked up by the blower 18 at the outlet of the separator 17 is therefore a cooled and purified gas which is returned into the receptacle 3 by way of the connecting channel 20, in order to ensure the cooling of the assembly 4. The device integrated in the body of the cupboard therefore functions in the closed-circuit mode, although a top-up of cooling gas can be ensured by means of an auxiliary argon tank (not shown). As can be seen in FIG. 1, each of the four cooling circuits of the cupboard comprises a blower, such as 18a, 18b and 18c, fastened to the upper part of the body 2 of the cupboard in the extension of a receptacle 22 and of a channel 16 connected to the central receptacle 3 of the cupboard by way of connecting channels 20 and 21. Arranged in each of the receptacles 22 is a separator of the cyclone type, such as the separator 17. The cooled and purified cooling gas delivered into a connecting channel 20 by means of the blower enters a radial channel of the guide piece 14 communicating with the central bore of the hollow grab 7. The guide piece 14 therefore comprises four radial channels arranged at 90.degree. relative to one another in the extension of the four connecting channels 20. The transfer cupboard according to the invention therefore has the advantage of making it possible to cool a fuel assembly, without the need to use auxiliary means located outside the body of the cupboard. The assembly is cooled by circulation of gas which is capable of carrying with it impurities, for example sodium aerosols and droplets of liquid metal, such as sodium, retained by the fuel assembly. The purification of the gas is carried out by means integrated in the body of the cupboard, and therefore the cooling device can function in a completely closed circuit. No part of the cooling circuit or cooling circuits is located outside the cupboard body, in which these circuits are completely integrated. This avoids the risk that oxygen will be introduced into the inert-gas cooling circuit or that a radioactive product will leak outside the cupboard. The cupboard according to the invention therefore has greater operating safety and a much smaller bulk than the assembly transfer devices according to the prior art. The cupboard according to the invention can comprise a single cooling circuit or any number of circuits less or more than four. The purification device associated with each of the cooling circuits can consist of a device other than a cyclone separator. The means for circulating the gas in the cooling circuit can likewise consist of devices other than blowers. It is also possible to add to each of the cooling circuits devices for cooling the gas circulating inside the main channel, for example devices assisting the heat exchanges between the gas and the cupboard body, such as blades, baffles or other devices for deflecting the circulation of the gas stream. These devices can also perform the function of separating the impurities carried along by the cooling gas. The means for recovering the liquid metal separated from the cooling gas can be produced in a different manner and be arranged in a part of the cupboard other than one described hereinabove. Finally, the cupboard according to the invention can be used for the transfer and storage of fuel assemblies, other than assemblies of fast-neutron nuclear reactors cooled by liquid metal.
	abstract	The present disclosure relates to a source wire assembly for radiographic applications, particularly for guiding a gamma ray source through a tubular path, such as with a radiographic projector. The source wire assembly includes a core of flexible metal cable, such as, but not limited to, aircraft cable, which may include wires and/or strands which are woven, twisted, helix wound or braided. A distal end of the source wire assembly is securely engaged to a Radioactive source capsule assembly while a proximal end of the source wire assembly is securely engaged to a connector housing for connection to driving equipment, such as, but not limited to, a push-pull operation associated with a radiographic projector, which may include source wire locking and safety mechanisms.
	abstract	A modular portable cask transfer (MPCT) facility is capable of transferring a canister containing spent nuclear fuel materials from or to a transportation cask respectively to or from a storage overpack. A transfer cask is utilized for the transfer. Telescoping legs enable movement of the transfer cask independent of the canister, which is moved using a hoist. Due to its modular configuration, the MPCT facility can be assembled, disassembled, and moved from one nuclear power plant to another.
	abstract	A particle therapy gantry for delivering a particle beam to a patient includes a beam tube having a curvature defining a particle beam path and a plurality of fixed field magnets sequentially arranged along the beam tube for guiding the particle beam along the particle path. In a method for delivering a particle beam to a patient through a gantry, a particle beam is guided by a plurality of fixed field magnets sequentially arranged along a beam tube of the gantry and the beam is alternately focused and defocused with alternately arranged combined function focusing and defocusing fixed field magnets.
044477295	abstract	A cylindrical container for the transportation of radioactive reactor elements includes a top end, a bottom end and a pair of removable outwardly curved shock absorbers, each including a double-shelled construction having an internal shell with a convex intrados configuration and an external shell with a convex extrados configuration, the shock absorbers being filled with a low density energy-absorbing material and mounted at the top end and the bottom end of the container, respectively, and each of the shock absorbers having a toroidal configuration, and deformable tubes disposed within the shock absorbers and extending in the axial direction of the container.
047864613	summary	BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to hold-down springs for holding nuclear reactor internals firmly in place and more particularly to Belleville type spring assemblies for clamping upper and lower reactor internals inside of a reactor vessel while providing a coolant flow path to the reactor vessel head region. 2. Description of the Prior Art Nuclear reactor cores are usually supported within a cylindrical core barrel arranged within a reactor vessel as a liner and hung from a flange formed where the reactor vessel and reactor vessel head are joined. The core and core barrel are commonly referred to as the lower internals. Coolant flows into the reactor vessel into an inlet annulus and is directed towards the bottom of the core barrel and then up through the core. During operation, the coolant is heated by the core. The heated coolant is then discharged from the reactor vessel as working fluid. Generally, a large pressure differential exists across the core which results in a very large "sailing" or lifting force against the core. This force actually tends to displace the core and its supporting structure. Positioned above the core in the pressure vessel are components known as the upper internals through which the heated coolant may pass before exiting from the pressure vessel. The upper internals are usually contained in a second cylindrical barrel axially aligned above the core barrel. The heated coolant, when passing through the upper internals, exerts a very considerable force against those components as well. In most pressurized water reactor (PWR) constructions, the upper internals barrel is also supported from the flange formed where the reactor vessel and reactor vessel head are joined. Because of the large size of the structures involved and the significant thermal gradients which exist in the reactor vessel, axial and radial differential expansions occur at the assembly of the vessel and core components. Because of these differential expansions and in large mechanical and hydraulic forces discussed above which act on these structures, the assembly must provide a large enough force to resist displacement. In addition, it is desirable to maintain the reactor vessel head region at inlet temperatures for safety reasons and to cool the upper internals drive components. Such cooling could only be achieved with a complex system of flow passages with prior designs which utilized a single large Belleville spring to provide a spring load and deflection capability for holding core barrel and upper internals barrel against deflection. With a large Belleville spring, a clamping load is developed when the reactor vessel head is lowered onto the Belleville spring and drawn down by head studs onto the reactor vessel flange. The spring is typically deflected on the order of only about 0.150 inch resulting in about 460,000 pounds of force to clamp the upper and lower internals against a machined ledge on the inside of the reactor vessel flange. Such loading is sufficient to prevent significant upward motion of the internals during normal operation and during seismic or LOCA events. However, with large (in the range of 14 to 16 foot diameter) Belleville springs, the loading force is developed over a very short deflection and therefore requires considerable precision. Moreover, large precision machined springs are expensive, difficult to heat treat and, because of their size and shape, difficult to handle, ship and replace. Moreover, with large springs a high stress is developed in the spring over a relatively small deflection which renders its performance vulnerable to stress relaxation after which replacement may be required to maintain adequate loading forces. Replacement is difficult not only because the spring is large but also because it is typically coated with a radioactive crud. Moreover, the size of a single spring is such that the replacement spring must come through a large hatch in the reactor containment resulting in long down times for the reactor. Moreover, many of the prior large spring designs comprised a 360.degree. structure which required a complex system of flow passages in order to pass inlet coolant to the upper head region. It should be understood that flow rates of up to 16,000 GPM (or on the order of 4% of the inlet flow) have to be accommodated. Disclosed in U.S. Pat. No. 4,096,034 is a structure for clamping a core barrel and upper internals band against hydraulic displacement by using a few, large Belleville spings mounted in vertical alignment with the wall of the upper internals barrel. No provision is made in the disclosed hold down structure for a Belleville spring assembly which permits an adjustable coolant flow to the upper reactor vessel head region. SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a reactor vessel having an inexpensive, testable, and easily replaceable spring assembly for holding reactor internals. It is a further object of the invention to provide a reactor vessel assembly including hold down springs having a flow passage for introducing coolant to the upper reactor vessel region. It is a further object of the present invention to provide a hold down spring assembly design for reactor vessels which is inexpensive, easily tested and easily replaced and which conservatively meets all application requirements. According to the invention, a nuclear reactor is provided which comprises a reactor pressure vessel and a lower internals assembly positioned within the reactor pressure vessel. The lower internals assembly has a core barrel with a flange having a plurality of annularly spaced coolant passages extending therethrough. An upper internals assembly is positioned within the reactor pressure vessel. The upper internals assembly includes an upper internals barrel having a flange which is axially disposed above the core barrel flange. The upper internals barrel flange has a plurality of annularly spaced core passages which, when the upper internals and core barrels are assembled, align with the coolant passages in the core barrel flange. A plurality of reactor internals hold down spring assemblies are annularly spaced about the core barrel flange between the core barrel and upper internals barrel flanges. In accordance with the invention, the hold down spring assemblies comprise a retainer having a central bore therein. The retainer carries a resilient biasing means, preferably a stack of Belleville springs. A passage means is disposed in the central bore for defining a flow passage between the coolant passages in the core barrel and upper internals barrel. Preferably, the core barrel and pressure vessel form an inlet coolant flow annulus in fluid communication with the coolant passages in the core barrel. The upper internals barrel and pressure vessel form an upper head region in fluid communication with the coolant passages in the upper internals barrel. In this manner, coolant from the inlet annulus flows through the core barrel coolant passages, the connecting flow passages, the upper internals barrel coolant passages, and to the upper head region of the reactor. Advantageously, the means defining a connecting coolant passage may comprise a bellows flange having an opening and fixed at one end of the central bore. A spring bellows is carried by the bellows flange and is disposed within the central bore. A movable plunger having a central opening is carried by the spring bellows, the plunger being adapted to be biased against one of the core barrel coolant passages by the spring bellows. Preferably, the retainer has an upper flange, adapted to seat against the upper internals flange, the upper flange being dimensioned to retain the stack of Belleville springs on the retainer when the stack is seated against the core barrel flange to resiliently support the upper internals barrel. Preferably, the plunger has a generally spherical end portion and the core barrel coolant passages have cone shaped seating surfaces. The spherical ends are biased against the seating surfaces by the bellows spring in order to effect a generally fluid tight seal therebetween. Advantageously, the upper bellows flange carries a central tube disposed within the spring bellows which extends toward but does not contact the plunger. Advantageously, the hold down spring assemblies include a locking nut adapted to cooperate with the retainer to preload the stack of Belleville springs. In another embodiment, the means defining a connecting coolant passage preferably comprises a first movable plunger which has a central opening and is movably retained within one end of the central bore and a second movable plunger having a central opening and which is movable within another end of the central bore. A spring bellows is disposed between the first and second plungers and within the central bore in order to bias the first and second plungers against the upper internals barrel and core barrel coolant passages respectively. In another advantageous embodiment of the invention, the core barrel flange is preferably formed of increased thickness and the spring assemblies are inserted in a cylindrical counter bore formed in the core barrel flange about the first plurality of coolant passages. This embodiment eliminates the need for shims or travel limiters in the pressure vessel assembly. Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention.
050911201	claims	1. Process for obtaining nuclear fuel pellets based on UO.sub.2 from metallic uranium, which does not lead to liquid effluents and gives intermediate, dense, pourable uranium oxide powders without any particular conditioning operation, such as granulation, comprising the steps of: oxidizing metallic uranium in an oxidizing gas at high temperature to obtain an oxide U.sub.3 O.sub.8 ; crushing or milling the U.sub.3 O.sub.8 to obtain a powder with an average grain size of approximately 10 to 30 .mu.m; chemically reducing the U.sub.3 O.sub.8 to UO.sub.2 ; activating the UO.sub.2 with the aid of at least one fine milling operation; and shaping by pressing and fritting. 2. Process according to claim 1, wherein the metallic uranium is oxidized by air or oxygen in the pure state or diluted by a neutral gas at a temperature not exceeding 600.degree. C. 3. Process according to claim 1, wherein the metallic uranium is oxidized in the presence of steam at a temperature not exceeding 800.degree. C. 4. Process according to any one of the claims 1 to 2, wherein the fine milling is a fluidized bed gas jet milling. 5. Process according to any one of the claims 1 to 3, wherein the oxidation phase of an oxidation-reduction cycle is performed with the aid of air or oxygen in the pure state or diluted by a neutral gas at a temperature not exceeding 600.degree. C. 6. Process according to any one of the claims 1 to 3, wherein the activated uranium oxide powder has a specific surface between 1.7 and 3.5 m.sup.2 /g. 7. Process according to any one of the claims 1 to 3, wherein prior to shaping, the activated UO.sub.2 powder is mixed with a metallic oxide in order to obtain mixed oxide fuel pellets. 8. Process according to claim 2, wherein the metallic uranium is oxidized by air or oxygen in the pure state or diluted by a neutral gas at a temperature between 400.degree. and 550.degree. C. 9. Process according to claim 3, wherein the metallic uranium is oxidized in the presence of steam at a temperature between 600.degree. and 750.degree. C. 10. Process according to claim 1, wherein activation of the UO.sub.2 is completed by at least one redox cycle. 11. Process for obtaining nuclear fuel pellets based on UO.sub.2 from metallic uranium, which does not lead to liquid effluents and gives intermediate, dense, pourable uranium oxide powders without any particular conditioning operation, such as granulation, comprising the steps of: oxidizing metallic uranium in an oxidizing gas at high temperature to obtain an oxide U.sub.3 O.sub.8 ; crushing or milling the U.sub.3 O.sub.8 to obtain a powder with an average grain size of approximately 10 to 30 .mu.m; activating the powder with the aid of at least one fine milling operation; chemically reducing the U.sub.3 O.sub.8 to UO.sub.2 ; and shaping by pressing and fritting. 12. Process according to claim 11, wherein the metallic uranium is oxidized by air or oxygen in the pure state or diluted by a neutral gas at a temperature not exceeding 600.degree. C. 13. Process according to claim 11, wherein the metallic uranium is oxidized in the presence of steam at a temperature not exceeding 800.degree. C. 14. Process according to any one of the claims 11 to 13, wherein the fine milling is a fluidized bed gas jet milling. 15. Process according to any one of the claims 11 to 13, wherein the oxidation phase of an oxidation-reduction is performed with the aid of air or oxygen in the pure state or diluted by a neutral gas at a temperature not exceeding 600.degree. C. 16. Process according to any one of the claims 11 to 13, wherein the activated uranium oxide powder has a specific surface between 1.7 and 3.5 m.sup.2 /g. 17. Process according to any one of the claims 11 to 13, wherein prior to shaping, the activated UO.sub.2 powder is mixed with a metallic oxide in order to obtain mixed oxide fuel pellets. 18. Process according to claim 12, wherein the metallic uranium is oxidized by air or oxygen in the pure state or diluted by a neutral gas at a temperature between 400.degree. and 550.degree. C. 19. Process according to claim 11, wherein the metallic uranium is oxidized in the presence of steam at a temperature between 600.degree. and 750.degree. C. 20. Process according to claim 11, wherein the oxidation phase of an oxidation-reduction is performed with the aid of air or oxygen in the pure state or diluted by a neutral gas at a temperature between 400.degree. and 500.degree. C. 21. Process according to claim 11, wherein activation of the UO.sub.2 is completed by at least one oxidation-reduction cycle. 22. Process for obtaining nuclear fuel pellets based on UO.sub.2 from metallic uranium, which does not lead to liquid effluents and gives intermediate, dense, pourable uranium oxide powders without any particular conditioning operation, such as granulation, comprising the steps of: oxidizing metallic uranium in an oxidizing gas at high temperature to obtain an oxide U.sub.3 O.sub.8 ; crushing or milling the U.sub.3 O.sub.8 to obtain a powder with an average grain size of approximately 10 to 30 .mu.m; chemically reducing the U.sub.3 O.sub.8 to UO.sub.2 ; activating the UO.sub.2 with the aid of at least one oxidation-reduction cycle; and shaping by pressing and fritting. 23. Process according to claim 22, wherein the metallic uranium is oxidized by air or oxygen in the pure state or diluted by a neutral gas at a temperature not exceeding 600.degree. C. 24. Process according to claim 22, wherein the metallic uranium is oxidized in the presence of steam at a temperature between 600.degree. and 750.degree. C. 25. Process according to claim 22, wherein the metallic uranium is oxidized in the presence of steam at a temperature not exceeding 800.degree. C. 26. Process according to any one of the claims 22 to 25, wherein the fine milling is a fluidized bed gas jet milling. 27. Process according to any one of the claims 22 to 25 wherein the oxidation phase of an oxidation-reduction cycle is performed with the aid of air or oxygen in the pure state or diluted by a neutral gas at a temperature not exceeding 600.degree. C. 28. Process according to any one of the claims 22 to 25, wherein the activated uranium oxide powder has a specific surface between 1.7 and 3.5 m.sup.2 /g. 29. Process according to any one of the claims 22 to 25, wherein prior to shaping, the activated UO.sub.2 powder is mixed with a metallic oxide in order to obtain mixed oxide fuel pellets. 30. Process according to claim 23, wherein the metallic uranium is oxidized by air or oxygen in the pure state or diluted by a neutral gas at a temperature between 400.degree. and 500.degree. C. 31. Process according to claim 22, wherein the metallic uranium is oxidized in the presence of steam at a temperature between 600.degree. and 750.degree. C. 32. Process according to claim 22, wherein the oxidation phase of an oxidation-reduction cycle is performed with the aid of air or oxygen in the pure state or diluted by a neutral gas at a temperature between 400.degree. and 500.degree. C.
052395685	abstract	A collimator assembly for removing selected radiation output from a specimen. The assembly includes collimator elements with each element having walls comprised of a first material covered by an inner layer of a second material which preferentially absorbs inelastic scattered radiation created in the first material.
	summary
	claims	1. A method of removing a jet pump disposed in a reactor pressure vessel of a boiling water reactor and configured to circulate a circulation cooling water, comprising the steps of: annularly cutting a peripheral portion of a retainer-mounting bolt, except a welded portion between the bolt and a retainer, in which the retainer connects a pump beam of the jet pump to an elbow portion and the bolt fastens the retainer to the elbow portion; rotating and loosening the bolt; removing the bolt, thereafter inserting a bolt retainer for preventing the retainer from falling down between the retainer and the elbow; rotating a head bolt mounted on the pump beam to thereby insert the retainer between a lower portion of the head bolt and a lower surface of the pump beam to thereby closely fasten the retainer to the pump beam and holding the retainer; taking out the pump beam together with the retainer to the outside of the reactor pressure vessel; and removing the retainer from the pump beam through an underwater remote control.
	description	This invention pertains to imaging equipment, and more particularly to a system and method for imaging fluctuations in the attenuation of penetrating radiation in an object or living creature. Several types of radiation have the ability to penetrate through objects or the body of living creatures. Properly used, these radiations offer non invasive techniques to create an image of the internal structure of different objects of interest, like non-living articles or living bodies. Any penetrating radiation can be used for attenuation-based imaging, if technical solutions to generate, collimate, guide and detect the radiation are available. Probably the most widely used penetrating radiation is x-ray. Other imaging methods may use the attenuation of gamma radiation, visible light, infrared radiation, terahertz radiation, ultrasound, electron beams or ion beams, and further development in this area can be expected. A few of the techniques utilizing these radiations are already well established, while a few are still being developed. Attenuation-based imaging techniques work by projecting beams of a penetrating radiation through an object of interest. The radiation is generated by a radiation source, and beams of the radiation are usually focused or collimated before passing through the region of the object to be imaged. The radiation is attenuated by the object of interest, and a shadow image (projection) of the region of interest is formed. To record the image, intensity of the emerging attenuated radiation can be detected by a detector, or set of detector elements. These detectors convert the intensity reading into a signal, which can be electronically processed. The image representing the distribution of absorption inside the object of interest can be reconstructed from the recorded intensities. FIG. 1 (prior art) shows the basic idea of the above image formation process in a flowchart. Step 102 includes the determination of the attenuation of a penetrating radiation in an object of interest along at least one projection line. Step 106 includes the reconstruction of the spatial distribution of the attenuation of the object in a viewable image. Such a simple data acquisition procedure, however, does not allow for the accurate determination of the error of the measured image nor the estimation of the variability of the attenuation inside the body. One interesting imaging method which uses electron beam as the penetrating radiation is electron microscopy. The transmission electron microscope uses electromagnetic “lenses” to control the electron beam. The electron beam is passed through a specimen and projected on an electron detector to record the shadow image of the specimen. Electron microscopes are used in the study of a broad range of organic specimens including biological specimens such as microorganisms, cells, large molecules, biopsy samples, and of inorganic specimens, including metals and crystals. Environmental electron microscopy is an electron microscopy technique that offers the advantage of visualizing biological samples in their native hydrated state. Projection images obtained using x-rays (radiographs) have been used in various fields since the discovery of x-rays. For many industrial, medical or research applications recording an x-ray shadow along one projection direction may be enough. In many uses, however, a more detailed three dimensional image of the object of interest may be desirable. Computed tomography (CT) combines several projections recorded from different directions (angles of view) to produce cross section images of the object of interest. The cross section images can be used to reconstruct a 3D image of the object of study. The created 3D or cross section images are typically visualized on a computer screen, printed, or reproduced on a film. Computed tomography is widely used in industry, research and also in medical imaging. In medical applications, the difference of the absorbance of different tissues gives enough contrast for the adequate diagnosis in many cases. If the contrast between different tissues is not enough, contrast agents are used to facilitate the examination. To describe the absorption and detection of different radiations it may be useful to think about radiation as particles. The particles of the electromagnetic waves are called photons. In the case of electron or ion beams the particle nature of the radiation is more obvious. The radiation intensity falling on a detector is proportional to the number of particles reaching the detector in unit time. The particle count reading of a detector, however, may vary even if the intensity falling on the detector is constant. The actual number of counted particles fluctuates around an average according to Poisson distribution resulting in the so called shot noise. This effect introduces a theoretically unavoidable inaccuracy in the intensity measurements of several penetrating radiations. Further error of the measured values can be caused by other factors, such as instrument noise. Depending on radiation type, and the contribution of different noise sources, the resulting measurements can have different distribution around a mean value. Poisson and Gaussian (normal) distributions were shown to occur in many cases. Several prior art patent documents try to identify motions in acquired projections. The aim of these works is to find projections which are recorded in a specific phase of the motion (U.S. Pat. No. 7,085,342 to Younis et al.), to remove motion artifacts from the images (U.S. Pat. No. 6,535,570 to Stergiopuolos et al., U.S. Pat. No. 6,879,656 to Cesmeli et al.), or to calculate physiologically interesting characteristics of the heart (U.S. Pat. No. 6,421,552 to Hsieh). All the techniques taught in these prior art documents are limited to extracting a few characteristics of a periodically moving organ and produce motion artifact corrected series of still images. Other prior art patent documents aim at minimizing the effect of the measurement error on the reconstructed image. One advantage of better image quality is the possibility of reducing the radiation dose used in imaging. Often, the published methods of the prior art allow an estimation of the error of the image as well. The disadvantage of these prior art methods, however, is that they are based on theoretical estimations of the variability of the measured data, rather than on a direct measurement. In U.S. Pat. No. 7,356,174, Leue and coworkers describe a method to estimate the effect of the inaccuracy of the x-ray detection on a reconstructed image. The method described in this patent suffers from several shortcomings. The method is designed only for situations in which the imaged x-ray densities are time independent, and assumes that measured photon counts follow Poisson distribution. The method of Leue and coworkers is not able to reconstruct the image of any attenuation fluctuations of the object. In fact, such attenuation changes may lead to less accurate image reconstruction by the above method, and/or less accurate estimation of the error of the image. In U.S. Pat. No. 7,187,794, Liang and coworkers describe a method for treating noise in low-dose computed tomography applications. After analyzing repeatedly recorded phantom scan datasets, Liang et al. conclude that in their case the noise is close to a normal distribution. Using the information acquired in the absence of a patient, this group proposes a means to lower the effect of noise on the reconstructed image of the patient. The method of Liang and coworkers is designed to image static structures, thus it can not visualize motions or fluctuations in the x-ray attenuation. Moreover, image reconstruction may become less reliable in the presence of such changes of attenuation. The method published by Fessler (U.S. Pat. No. 6,754,298) reconstructs an image from a plurality of projection data recorded at different x-ray photon energy distributions. Similarly to the two patents described above, this technique also assumes a static object of study, and the gained image may deteriorate if this assumption is violated. In U.S. Pat. No. 7,103,204, Celler and coworkers publish a method to track changes in the photon emission of an object. Their main purpose, however, is to represent movements as a series of image frames, rather than to determine the extent of movements in the pixels. Also, the method works on emission-based imaging techniques, and not transmission measurements. In U.S. Pat. Appl. No. 2005/0,226,484, Basu and coworkers publish a method to estimate the variance of generated 3D CT images. Their method starts from the assumption that the variance originates only in the noise of the measurement which is dominated by the photon shot noise. As a consequence of this assumption, the method described in U.S. Pat. Appl. No. 2005/0,226,484 is incapable of generating images representing the attenuation fluctuation of the object of interest. Many image processing methods (e.g. U.S. Pat. No. 6,256,403 to Florent and coworkers) calculate the pixel variance of images from the neighborhood of the given pixel. The result of such calculations reflects the variance of the image along the space coordinates in a certain region, and can not represent time dependent fluctuations. In U.S. Pat. No. 6,169,817, Parker and coworkers describe a method of 4D (space and time) visualization of image data. Spatial (regional) variance is calculated for individual image frames to determine connectivity of pixels in the image. Temporal changes are represented as a series of consecutive still images. This method is also incapable to represent attenuation fluctuations. Patent No. EP 1,959,397 to O'Halloran and coworkers focuses on the removal of motion artifacts from images. The method uses HYPR reconstruction to represent the imaged object as a snapshot taken at different times during the motion. This method focuses on removal of motion artifacts to generate still images, and it is not designed to represent local fluctuations. The principle objective of the invention is to provide a new imaging modality which may represent internal motions or fluctuations of at least one imaged object of interest. The object of interest may be a non-living article, or living creature, or part of an article or part of living creature. Internal motions may be imaged by the analysis of the associated fluctuations in the attenuation of a penetrating radiation. A further objective of the invention is to allow a more accurate reconstruction of the mean attenuation image and give a better estimation of the error of the reconstructed images. In one embodiment the present invention provides for a method for imaging an object of interest using penetrating radiation, characterized in that said method comprises: (a) providing a plurality of measurements of the penetrating radiation passing through the object of interest along at least one direction of detection; (b) processing the plurality of measurements to obtain at least one statistical parameter capable of describing a width of a temporal distribution of the plurality of measurements for each direction of detection; (c) and reconstructing the image of the object of interest based on the at least one parameter describing the distribution of the plurality of measurements, thereby obtaining images of the object of interest. In another embodiment the present invention provides for an image processing method for determining relative movement of structures within an object of interest, characterized in that said method comprises: (a) providing a plurality of measurements of a penetrating radiation through the object of interest along at least one direction of detection; (b) processing the plurality of measurements to obtain at least one parameter which describes a fluctuation of the plurality of measurements for each of the at least one direction of detection; (c) and reconstructing an image of the object of interest based on the at least one parameter, wherein said reconstructed image based on the fluctuation of the plurality of measurements provides information on the relative movement of structures within the object of interest. In another embodiment the present invention provides for a system for reconstructing an image of an object of interest characterized in that said system comprises: (a) a source capable of substantially emitting penetrating radiation; (b) a detector sensitive to said penetrating radiation, said detector capable of producing a plurality of measurements related to the penetrating radiation passing through the object of interest; (c) a processor means having at least one algorithm for calculating at least one statistical parameter capable of describing a width of a temporal distribution of the plurality of measurements for each direction of detection; and (d) an image reconstruction processor means for reconstructing the image of the object of interest based on the at least one parameter describing the distribution of the plurality of measurements. Overview Disclosed herein, in one embodiment, is a new imaging modality capable of representing relative internal motions of imaged objects of study through the associated fluctuations in the attenuation of penetrating radiation. FIG. 2 is a flowchart of data acquisition, data processing and image reconstruction according to one embodiment of the present invention. A comparison between the flowchart represented in FIG. 2 to the one show in FIG. 1 (prior art) illustrates changes in data acquisition and analysis as well. In the embodiment of FIG. 2, a plurality of measurements using a penetrating radiation in an object of study may be collected along at least one projection line. Temporal distribution of the collected plurality of measurements may be characterized by the calculation of any suitable statistical parameters. The statistical parameter may then be used for the reconstruction of images describing the calculated temporal distribution of the penetrating radiation in the object of study. In one embodiment of the present invention, the statistical parameter may describe the width of the temporal distribution of the measurements. In another embodiment of the present invention, the statistical parameter may describe the center of the temporal distribution of the plurality of measurements. In another embodiment, the statistical parameter may describe the error of a statistical parameter describing the temporal distribution of the plurality of measurements. For example, the statistical parameter which may describe the width of the temporal distribution of the measurements may include, without limitation, a variance, a standard deviation, expected deviation, average absolute deviation or a moment of the distribution of the measurements obtained using the penetrating radiation. The statistical parameter which may describe the center of the temporal distribution of measurements may include, without limitations, an average, a mode, a mean or an expected value of the plurality of measurements. An error of all the parameters mentioned in this paragraph may also be used for the reconstruction of images. In embodiments of the present invention, the plurality of measurements may be related to the intensity of the penetrating radiation passing through the object of study. For example, the plurality of measurements may include, without limitation, attenuation measurements of the penetrating radiation through the object of study or the electric field strength of the penetrating radiation through the object of study. Example of penetrating radiation that may be used with the present invention, include, without limitation, electron beams, gamma radiation, infrared radiation, infrasound, ion beams, microwaves, radio waves, shock waves, sound, terahertz radiation, ultrasound, ultraviolet radiation, visible light or x-rays. Various changes may be made in the embodiments and operating methods presented below without departing from the spirit or scope of the invention. All matter contained in the descriptions or shown in the accompanying drawings should be interpreted as illustrative and not in a limiting sense. Applications The invention disclosed herein may have several applications, a few of which may be described below. The descriptions provided herein below are for illustrative purposes only, and should not be taken as limiting the scope of the invention. Fluctuation imaging of deformations of the object of interest may be of particular importance. The object of interest may be agitated by sound, ultrasound, shock waves, pressure, etc, and the resulting internal fluctuations recorded. Fluctuation imaging of the deformations may provide information about weaknesses of manufactured or built structures. In such way the weaknesses may be discovered before any cracks of measurable size weaken the structure. The imaging methods provided herein may be particularly useful if failure of the structure risks the life or health of humans, or may cause costly damages. Fluctuation imaging may also be used to map the deformability of the object of interest. This may be important in many fields, including engineering and medical imaging. In these techniques, the object of interest may be exposed to mechanical stress, pressure waves, shock waves, vibrations, infra-sound, sound, or ultrasound while recording a fluctuation image. The method may give a new type of image contrast based on the elasticity of the different parts of the object of interest. This method may yield useful diagnostic images even if the inherent fluctuation or motion of different tissues and/or deposits can not be directly visualized in a fluctuation image. Benefits The invention disclosed herein may have many economical, technical and health care benefits. Described herein are a few uses and benefits of the invention for illustrative purposes only. These descriptions should not be taken as limiting the scope of the invention. Imaging by penetrating radiations produces several tens of billions of dollars sale per year, and is constantly increasing. Penetrating radiations which may be used in medical imaging systems, including, without limitation, computed tomography, X-ray microanalysis, microtomography, electron microtomography, ion microscopy, testing electronics parts, etc. One important field of imaging is medical imaging. Image quality may be important while radiation dosage in many applications has to be kept low. Often, contrast agents have to be used to improve image quality. The sale and use of contrast agents constitutes a several billion dollar market itself. In addition to this, the use of contrast agents may trigger unwanted reactions (for example allergic response), which may cause additional risks for the patient. Existing imaging modalities have a very wide use in industry, medical diagnosis, healing and research. Resolution of imaging equipments is constantly improving. The smallest resolvable distance of modern environmental electron microscopes may be less than 1 nm, which is in the range of the size of molecules. Fluctuation images recorded in an electron microscope in accordance to one embodiment of the present invention thus may yield information about the relative molecular scale movement of the object of interest. The smallest resolvable distance for medical x-ray computed tomography may be as small as 0.2 mm, whereas the resolution of small animal computed tomography may be 0.05 mm. This is roughly the size range of single cells. X-ray computed tomography fluctuation images obtained in accordance to the present invention may thus reflect the relative cellular movements of tissues. Due to the high spatial resolution of medical x-ray computed tomography, relative movements at the cellular level may become visible, which may have an impact in the diagnosis of many diseases as well as planning, monitoring and controlling treatment. At present, x-ray computed tomography is too slow for direct tracking of many movements. Also, repeated imaging of the human body could result in higher radiation doses and higher associated health risks. One aim of the invention disclosed herein may be to introduce a new imaging modality. This new modality may be able to record and analyze fluctuations of the attenuation of penetrating radiation in an object of interest. Another aim of the present invention may be to provide a new and better estimation of the average attenuation image and of the inaccuracy of the average attenuation image. The disclosed new methods of the present invention may not require the use of higher doses of radiation. The amount of radiation which may be used in present versions of imaging instruments (or even less) may be split in a plurality of measurements, to record a plurality of readings. Readings may than be used to determine both the width of the readings or the expected value of the readings (or average, or sum, or any equivalent statistical parameter) as before. The disclosed invention may prove useful in several ways. The new imaging modality of the present invention may give access to new type of information not available up to now. The new imaging modality of the present invention may also show new material contrast schemes allowing better visualization of structures. The invention may allow for a better estimation of the average attenuation image, and it may also make possible a better estimation of the error of the average attenuation image. These advantages may be useful where penetrating radiations may be used for imaging. In many fields of use, no new market for the present invention may need to be created. Customers interested in attenuation based imaging may find the more accurate estimation of the mean attenuation image, and the better estimation of the variance of the images obtained in accordance with the present invention useful. Also, earlier users of existing imaging modalities may not need extra training to be able to use the new imaging modality of the present invention. The new imaging modality of the present invention may introduce new contrast schemes, which may allow new applications and may open new markets as well. The new imaging modality of the present invention may require only minor modification of existing data acquisition modules and data processing procedures. This may have several advantages: i) the costs of the development necessary to integrate the new modality into presently manufactured equipment may be small; ii) manufacturing instruments in which the new modality has been integrated may not be more expensive than the present instruments lacking the new modality; iii) switching to manufacture instruments with the new modality incorporated may not need large changes in the production procedures; iv) modifications required for the new modality and new methods may inexpensively be added to imaging devices installed earlier. The new methods of the present invention thus may be installed for established customers as well. A better estimation of the error of the image may also be used for better denoising of the average images. In medical imaging, a better estimation of the average image may yield better image quality, which may allow reduction of the exposure of patients to the radiation used for imaging. A better estimation of the error of the image may also help to optimize radiation intensity and measurement time necessary to get the diagnostic information. This, in turn, may help to avoid unnecessary patient doses. New material contrast schemes may also allow the reduction of the patient doses in cases where imaging is traditionally difficult due to low contrast between tissues. New contrast schemes may also allow the use of double modality contrast materials. MRI contrast agents (such as Gd, or FenOm compounds) may also serve as contrast agents for the x-ray fluctuation detections. The use of such dual contrast agents may reduce the need of contrast agents in dual modality MRI and X-ray CT measurements, or improve the X-ray image quality without the use of extra contrast materials. Fluctuation images may find several important applications in the field of medical computed tomography. Different tissues may show a different extent of movement and fluctuation. These movements may also have a different time-course. Faster dividing tissues may show more fluctuations, while non-living deposits may be virtually still. An image showing the extent or the speed of fluctuations may thus be used effectively to diagnose several diseases. For example, fluctuation attenuation images obtained in accordance with the present invention may have several advantages over recording only the mean attenuation image. Fluctuation images may be less sensitive to the presence of relatively high background attenuations. In images representing only the mean attenuation, features giving a small modulation of the mean attenuation may not be discernible if a high background attenuation is present. Fluctuation images may remove the mean background and may allow visualizing parts, which may give a small fluctuating contribution. The proposed new imaging modality of the present invention thus introduces a new, fluctuation-based contrast. Better contrast may result in better image quality and a possibility to lower the patient dose. Introducing the new modality thus may decrease the risks of the examination. Cancer is one major cause of human death. It caused about 13% of the deaths in 2007, which means that 7.6 million people dyed of cancer in that year. Early diagnosis of cancer is vital to the successful treatment. Although methods for diagnosing cancer exist, a better and/or independent method could give higher diagnostic sensitivity, and thus higher treatment success. Cancer tissues divide faster, and contain more blood vessels than healthy ones. With appropriate timing of the data acquisition this may also mean larger fluctuations. These differences between cancer and healthy tissues may be used as a diagnostic signature of tumors in fluctuation images. Inflammation is the response of the vascular and the immune system to infections. In autoimmune diseases inflammation attacks the patients own tissues. Both in healthy and in pathologic inflammations it is important to identify and localize the inflammation. Inflammations have a higher metabolic rate, with more blood flow and the presence of more immune cells. All these may cause that inflammations have a distinct signature in the fluctuation images. Approximately two dozen human diseases have been linked to the formation of ordered insoluble protein aggregates called amyloid. Amongst the diseases linked to the formation of such amyloid plaques are Creutzfeldt-Jacob disease (the human variant of mad cow disease), Alzheimer disease, Parkinson disease, and type II diabetes. At present there is no method for visualizing or tracking the deposition of amyloid plaques. Diagnosis of the amyloid related diseases happens in a later phase, when the symptoms already become visible. Amyloid plaques are inert non-living inclusions. In a fluctuation image these plaques may show up as motionless bodies, thus giving a marker for their identification. Even though the plaques and the surrounding tissue look the same in the images representing the mean of the attenuation, they may clearly separate in the fluctuation images. Above we explained in more detail the possibility of diagnosing amyloid related diseases, but the benefits described in the above paragraph may be used for the diagnosis of any non-living material inside the body. These include, but are not limited to the visualization of any stent, stone, plaque, deposit or inclusion, in any part of the body. Obtaining an image of blood vessels with suitable contrast traditionally requires the injection of contrast agents into the bloodstream. Blood is a fluid tissue with a variety of cells with different sizes flowing in the blood vessels. As the cells move with the bloodstream, they cause a fluctuating density in the recorded projections. In a fluctuation image the blood flow may thus be directly visualized without the use of contrast agents. The periodic pumping of the heart may also periodically move the wall of the blood vessels, which may give a sharper contrast of the walls of the vessels in the fluctuation image. Fluctuation imaging of the heart, lungs, or other moving organs may also be possible, as illustrated in FIGS. 9 and 10. The method of the present invention would not represent the movement as a series of sharp still images. The method of the present invention may be able to determine the fluctuation of the attenuation in every point. The methods of the present invention may yield useful diagnostic information, and it may also need less radiation exposure. As shown in the above examples, the new imaging modality of the present invention may advance diagnosing several types of diseases, like cancer, conditions of the vascular system, autoimmune diseases, amyloidoses, and so forth. For many of these there is a high and increasing demand due to the aging population of the western societies. For some of these conditions there is no diagnostic method at present, so the new modality may not have competing alternatives. Fluctuation images may also be used in imaging of several physical phenomena or engineering processes including but not limited to the ones listed below. Fluctuation images may be used in identifying regions which have different x-ray density than their environment while the object of study may be moved on a production line. Imaging of fluctuations may prove useful in characterizing the movement or explosion of fuel in engines. Fluctuation images may give better insight in the movement of fluids in or around objects such as fans, turbines, wings, and so forth. Visualization of the flow may help a better optimization of the work conditions of engines, power plants, airplanes and so forth. Imaging of fluctuations may also help visualize fluctuations of electric discharges which may also contribute to optimization of spark gaps, motors, lamps, and so forth. Several published methods aim to minimize the effect of the inaccuracy of the measurement on the reconstructed image. Here we provide a new method to estimate the inaccuracy of the average attenuation image as well. By handling better the variability of the measurements, our new method may yield better image quality. This may allow reduction of patient dose in medical applications. Other Embodiments Variations or modifications to the design and construction of this invention, may occur to those skilled in the art upon reviewing this disclosure. Such variations or modifications, if within the spirit of this invention, are intended to be encompassed within this provisional patent application, as well as within the patent applications intended to be filed based on it, and the resulting patent protection issuing upon this invention. Conclusions, Ramifications, and Scope The description previously provided contains many specifications. These should not be construed as limiting the scope of the embodiments, but as merely providing illustrations of some of the presently preferred embodiments. In all aspects of the present disclosure, penetrating radiation means any radiation or wave that is capable of penetrating through the studied object of interest. These may include, but are not limited to: x-ray, gamma radiation, visible light, infrared radiation, terahertz radiation, ultrasound, electron beams, ion beams, or shock waves. In one embodiment, a plurality of detector readings may be use to get measurement information about the variation of the strength of the penetrating radiation. The plurality of measurements may be done in many ways. In a simplest case detection may be performed in a plurality of identical acquisition time intervals which may or may not be separated by inactive time periods in which the detector is not collecting data. Any other data acquisition pattern may also be successfully used if it produces a plurality of data for the subsequent calculation of the required statistical parameters. Such acquisition patterns may include, but are not limited to methods using detection and inactive periods of varying length, methods which record the impact time of individual particles, or methods which record the time between the impact of individual particles. It should be understood that the term “measurement” would be not only the detector reading itself, but also any number or parameter calculated from the detector reading. In the examples presented in this document the detector recorded the intensity of the penetrating radiation. Instead of intensity, other embodiments may use any other physical quantity indicating the strength of the radiation, including, without limitation photon number, electron number, ion number, pressure, pressure change, oscillation speed, electric field strength, or magnetic field strength, or any mathematical function of these quantities. In the presented embodiments the detector unit records the strength of the penetrating radiation. Many other embodiments of the detector can be built which allow quantification of the intensity fluctuations. Such detection methods include, but are not limited to the use of electronic cards directly evaluating the variation of the signal, detectors that are sensitive to derivatives of the radiation intensity, modulation of detector sensitivity, or modulation of the intensity of the penetrating radiation. Detector readings used for the evaluation of the intensity variations could be made with the same detector element, but this is not a necessary condition. Embodiments may be created which use different detectors or detector elements to gather information about the variation of the intensity of the radiation. Presented embodiments used intensities measured along the same line to determine fluctuations of the object of study. It is contemplated that intensity readings along different lines may also be used for the reconstruction of the mean attenuation and fluctuation images. Images representing fluctuations in time may also be produced by the reconstruction of a plurality of simple image scans and calculating the parameter describing time variance of the signal from the reconstructed images. Presented embodiments determine at least one quantity describing the fluctuation of the attenuated intensity of the penetrating radiation. It should be understood that any quantity which relates to the attenuation of the radiation (transmission, absorption, extinction, extinction coefficient, attenuation coefficient, mass attenuation coefficient, half value thickness, transmitted intensity, any mathematical combination of these, and so forth) may also be used instead of the attenuation. Also, any parameter that may be used to describe the time course and/or size of the fluctuations is also suitable. Such parameters include, but are not limited to the variance, standard deviation, expected deviation, average absolute deviation, any moment or central moment of the distribution, characteristic time of the fluctuations, relaxation time of the fluctuations, Fourier components, and so forth. One embodiment of the present invention takes into account the Poisson distribution of the photon counting instrument noise. This should not be understood as limiting the scope of the embodiments. This distribution is merely one example for the inherent variation of the detector readings, which may be observed in the absence of fluctuations inside the object of interest. We contemplate that other embodiments may take in account any other distribution of the inherent variation of the detector readings. The inherent random variation of the detector readings may be empirically determined, theoretically derived, or the result of a combination of the two. We also contemplate that in the case of larger intensities and more substantial attenuation fluctuations this correction may be altogether negligible. The above disclosure generally describes the present invention. A more complete understanding can be obtained by reference to the following specific Examples. These Examples are described solely for purposes of illustration and are not intended to limit the scope of the invention. Changes in form and substitution of equivalents are contemplated as circumstances may suggest or render expedient. Although specific terms have been employed herein, such terms are intended in a descriptive sense and not for purposes of limitation. The examples are described for the purposes of illustration and are not intended to limit the scope of the invention. FIG. 3 illustrates a diagram of an environmental transmission electron microscope (ETEM) which may be capable of collecting measurements and reconstruct at least one image of at least one object of interest in accordance with one embodiment of the present invention. The ETEM uses electron beams as penetrating radiation to visualize the object(s) of interest. Other embodiments may use any other penetrating radiation including, but not limited to gamma radiation, infrared radiation, infrasound, ion beams, microwaves, radio waves, shock waves, sound, terahertz radiation, ultrasound, ultraviolet radiation, visible light. If other penetrating radiation is used, shaping of the radiation beam may require different elements (for example: collimator, lenses, electron optics, ion optics and so forth). The embodiment presented in FIG. 3 may reconstruct at least one image of the object of interest based on any or several of the following: the average attenuation, the error of the average attenuation, the fluctuation of attenuation, and the error of fluctuation of attenuation of the penetrating radiation absorbance of the object of interest, or any other statistical parameter which may describe the temporal distribution of the collected measurements. Instead of intensity, further embodiments may use any other physical quantity which may be related in any way to the intensity of the radiation, including, without limitation, electric field strength, magnetic field strength, photon number, electron number, ion number, pressure, pressure change, or oscillation speed. Other quantities which may be related to the intensity may also be used instead of intensity, such as transmission, absorbance different functions of intensity, and so forth. The illustrated system of FIG. 3 includes an electron gun 302 emitting a beam of electrons 304. The electron gun 302 may be connected to an electron gun controller 352. The electron gun controller 352 may control the timing, intensity, and kinetic energy of the electrons used in imaging the object of interest. The electron beam 304 may be passed through a condenser electron optics 306 before entering an environmental cell 308. The condenser electron optics 306 may be controlled by a condenser electron optics control system 356. The environmental cell 308 may be coupled to an environmental cell control system 358. An electron beam 310 will reach a specimen (object of interest) 312. The object of interest 312 may be placed on a specimen stage 314 coupled to a specimen stage control system 364. The environmental cell 308 may provide a possibility to regulate the pressure and composition of the gas atmosphere around the object of interest 312 placed inside the environmental cell 308. A portion of the electrons of the beam 310 may pass through and around the object of interest 312. The portion of the electrons which may pass through the object of interest may form an electron beam 316, which may fall on a detector 320. The electron beam which may pass through and around the specimen 312 may be focused on the electron detector 320 by a projection electron optics 318 which may be controlled by a projection electron optics control system 368. The detector 320 may include at least one element, which may be able to detect electrons. The detector 320 in this exemplary embodiment may be a CCD camera attached to a scintillating crystal. Other embodiments may use different image sensors instead of the CCD (for example photon-multiplier tube array, or CMOS sensors, and so forth). In this embodiment, the detector 320 may be any detector which may be capable of detecting the impact of electrons. In this embodiment, the electron detector 320 may be controlled by an electron detector controller and data acquisition system 370. In embodiments which may use other forms of penetrating radiation, the radiation may be detected with different detectors sensitive to the actual radiation used in the embodiment (for example photon multiplier, CCD camera, piezoelectric detector and so forth). In the exemplary embodiment of FIG. 3, the electron detector 320 may produce electrical signals which may represent the attenuated intensity of the incident electron beams. In this embodiment, the electron detector controller 370 may receive analogue electrical signals from the detector 320 and may convert the analogue data to digital signals for subsequent processing by a computer means 350. An analogue to digital converter may also be incorporated in the detector, to obtain digital data from the detector. The intensity measurements detected by the detector 320 may be needed to reconstruct any image of the object of interest. The electron gun control system 352, the condenser electron optics control system 356, the environmental cell control system 358, the specimen stage control system 364, the projection electron optics control system 368, as well as the electron detector control and data acquisition system 370 may be coupled to a computer 350. In the described embodiment of FIG. 3 several control units may command the subunits of the ETEM to perform tasks connected to the data collection and processing. In one embodiment, a few or all of the controllers may be built of several units, performing some part of the tasks. In another embodiment several of the controllers may be grouped or integrated in larger units which may perform the control tasks of several or all of the mentioned control units. In one embodiment, instead of the computer 350, a combination of a plurality of general purpose and/or application specific digital computers may be utilized. In the described embodiment of FIG. 3, different parts of the imaging equipment may communicate by electric signals, but connections may be done by several other methods. Any method suitable of transferring the necessary information may be used. For example, data may also be transferred by the means of optical cable, or wireless connection, and so forth. The collected data may be transferred to the computer 350, and stored in the digital memory of the computer 350, or any storage device which may be part of, or coupled to the computer 350. Any type of memory capable of storing the collected data may be utilized. The memory may be local to the data acquisition system, or may include remote components. The computer may be local to the imaging device, or may be remote from it, coupled to the imaging device through a network, or other remote connection. The network may also be connected to a remote client or database. Acquired data, imaging parameters, reconstructed images may be visualized by many methods. These methods include, but are not limited to visualizing on screen, printing on paper, slide, or film. The computer 350 may receive commands, settings and scanning parameters from an operator who controls the imaging system via input devices of the computer. The operator may observe the data or the reconstructed images, set input parameters, initiate imaging, and so forth. The operator may be local to the computer 350, or may be remote from it, coupled to the computer 350 through a network, or other remote connection. Some or all of the data processing described here may be performed remotely. In this exemplary embodiment, the reconstructed image may visualize the internal structure of objects of interest which can be penetrated by electron beams. FIG. 4 is a flowchart including exemplary steps for generating images reconstructed from statistical parameters describing the temporal distribution of the attenuated electron beam radiation passing through the object of study and captured by the detector, including, without limitation, the width of the temporal distribution of the attenuated electron beam, the center of the temporal distribution of the attenuated electron beam, and their respective estimated errors using the system described in FIG. 3. In step 402 an electron beam 304 may be generated by the electron gun 302; the beam 304 may be shaped by the condenser electron optics 306 in step 404, and may be passed through the object of interest 312 in step 406. In step 408 the portion of the electron beam 316 which passed through the object of interest 312 may be projected on the detector 320 by the projection electron optics 318. In step 410 measurements representing intensity data along at least one direction may be collected. In step 412 at least one statistical parameter describing the temporal distribution of the collected measurements may be calculated. Examples of statistical parameters may include the average density, deviation of the density and their respective errors. In step 414 images representing the at least one statistical parameter describing the temporal distribution of the density of the electron beam in the object of interest 312 may be reconstructed. As will be appreciated by those skilled in the art, intensity readings of the detector 320 may be subject to fluctuations. These fluctuations may be due to random noise of the measurement or to real changes in the attenuation of the penetrating radiation inside the object of interest 312. Random noise may come from the Poisson shot noise of the detection, from electronic noise of the detector, or attached electronics parts, etc. Random noise may have no information content about the object of interest 312. Fluctuations arising from real attenuation changes of the object of interest 312 may carry important information about the movements of the object of interest. The described exemplary embodiment of FIGS. 3 and 4 is an ETEM which may create an image representing, for example, the average intensity of the electron beam and/or another image representing the fluctuation of the intensity. In one embodiment, to determine the image of the object of interest 312, the presented embodiment may record the intensity I of the electron beam 316 passing through the object of interest 312 for every pixel of the image. Making a plurality of intensity detections for every pixel may reveal that the measured I intensity fluctuates. If I0 denotes the intensity of the electron beam before the absorber, I the intensity after the absorber, and D denotes the attenuation of the electron beam due to the absorber, then:I=I0·Exp[−D] (1) Here Exp[. . . ] denotes the e-based exponential function. The intensity I of the electron beam can be estimated by a detector that counts the electrons that fall on a given surface area in a given time interval. In this embodiment it will be assumed that the attenuation D for the electron beam follows normal distribution due to movements. In such case the intensity I will follow lognormal distribution. In this embodiment it will also be assumed that the intensity measurement has a Poisson shot noise. Taking into account both sources of fluctuations the following expressions may be obtained for the expected value and variance of the detected electron numbers k:E(k)=I0·Exp[Var(D)/2−E(D)], (2)Var(k)=I0·Exp[Var(D)/2−2·E(D)]·(Exp[D]−I0·Exp[0.5·Var(D)]+I0·Exp[1.5·Var(D)]) (3) If the expected value E(k) and variance Var(k) of the electron counts k are determined experimentally, the expected value E(D) and the variance Var(D) of the attenuation D may be calculated by solving the above equations:E(D)=Log[I0·Sqrt[Var(k)−E(k)+E(k)2]/E(k)2], (4)Var(D)=2·Log[Sqrt[Var(k)−E(k)+E(k)2]/E(k)] (5)where Log[ . . . ] denotes the natural (e-based) logarithm, Sqrt[ . . . ] denotes the square root function. The expected value E(k) and variance Var(k) of the electron counts are parameters that describe the theoretical distribution of the counts k. These parameters can not be determined directly, but they can be estimated from measurements. The presented embodiment may make a plurality (n) of electron count readings and may calculate an estimation for both the expected value E(k) and variance Var(k). To estimate the error of the estimation of E(k) and Var(k) any statistical method (such as jackknifing, bootstrapping, and so forth) may be used which allows a reasonably accurate guess of the errors. After estimation of the errors Err(E(k)) and Err(Var(k)), the expressions for the errors of the expected value E(D) and the variance Var(D) may be derived from the expressions for E(D) and Var(D). After simplifying the expressions, Err(E(D)) and Err(Var(D)) may be calculated the following way:Err(E(D))=(E(k)^2−1.855·E(k)+2·Var(k))·Var(k)/(Sqrt[n]·E(k)·(E(k)^2−E(k)+Var(k))), (6)Err(Var(D))=(1.71·E(k)−2·Var(k))·Var(k)/(Sqrt[n]·E(k)·(E(k)^2−E(k)+Var(k))). (7) As described above, the presented embodiment may use a plurality of detector readings k to calculate an estimation for (1) the expected value E(D), (2) the variance Var(D), (3) the error of the expected value Err(E(D)), and (4) the error of the variance Err(Var(D)) of the density D. These four quantities may be represented as four different images. The image of the expected value may represent information similar to conventional electron microscopy images. The variance image may reflect the fluctuations of the object of interest. This new modality may be used to image relative movement of structures inside the object of study. The new modality may bring new contrast schemes, which may allow the visualization of structures which were not previously resolvable. The error images hold information important for optimization of data acquisition, for efficient image analysis, denoising, automatic shape recognition, and so forth. Other embodiments may be envisioned which may use different statistical parameters to describe the “typical” reading and/or width of the distribution of the measured data or of the attenuation D. FIG. 5 illustrates a diagram of another embodiment of the present invention: an x-ray computed tomography system which may be used to collect measurements and to reconstruct at least one image of at least one object of interest. The presented embodiment may reconstruct at least one image of any or several of the following: the average attenuation, the error of the average attenuation, the fluctuation of attenuation, and the error of fluctuation of attenuation of the x-ray absorbance of the object of interest, or any other statistical parameter which may describe the temporal distribution of the collected measurements. This embodiment uses x-rays to obtain images of at least one object of interest. Other embodiments may use any other penetrating radiation including, but not limited to electron beams, gamma radiation, infrared radiation, infrasound, ion beams, microwaves, radio waves, shock waves, sound, terahertz radiation, ultrasound, ultraviolet radiation, visible light. If other penetrating radiation is used, shaping of the radiation beam may require different elements, including, without limitation, collimator, lenses, electron optics, ion optics and so forth. If other penetrating radiation is used, the radiation may be detected with different detectors sensitive for the actual radiation used in the embodiment, including, without limitation, photon multiplier, CCD camera, piezoelectric detector and so forth. The system illustrated in FIG. 5 may include a source 502 emitting x-radiation 504. Any suitable source of high energy photons may be used. These alternative sources may include one or more gamma emitting isotopes, or less traditional x-ray emitters (such as x-ray sources using nanotubes as cathode, and so forth). In the exemplary embodiment of FIG. 5 the x-ray source 502 may typically be an x-ray tube connected to an x-ray source controller 552. The x-ray source controller 552 may control the timing and intensity of the emission of the x-ray source. Adjacent to the x-ray source 502 a collimator 506 may be positioned, through which an x-ray beam 508 may reach the object of interest 514. The collimator 506 may be controlled by a collimator controller 556. The object of interest 514 may be the body or part of the body of a patient or an object or part of an object. As it will be described later, other embodiments may include x-ray sources with different geometry, which may or may not use a collimator. The portion of the x-ray beam 508 which may pass through or around the object of interest is the x-ray beam 516, which may hit an x-ray detector 518. The detector 518 may contain at least one detector element, which may be sensitive to x-radiation. The detector 518 may include a scintillation element, or a direct conversion material. The x-ray detector 518 in this exemplary embodiment may be a detector array, which may be coupled to an x-ray detector controller 568. In this exemplary embodiment, detector elements of the array may produce electrical signals that represent the intensity of the incident x-ray beams. In this exemplary embodiment, the x-ray detector controller electronics 568 may typically receive analogue electrical signals from the detector 518 and may convert analogue data to digital signals for subsequent processing by a computing means 550. In one embodiment an analogue to digital converter may also be incorporated in the detector, to obtain digital data directly from the detector. The intensity measurements done by the detector 518 may undergo pre-processing and calibration to condition the data to represent the line integrals of the attenuation coefficients of the scanned object of interest. The obtained projection data may then be filtered and may be used to reconstruct at least one image of the scanned area or part of the scanned area. The exemplary embodiment presented in FIG. 5 may also involve a rotational subsystem 510 connected to a rotational subsystem controller 560 and a translational subsystem 512 connected to a translational subsystem controller 562. The rotational subsystem 510 and the translational subsystem 512 may allow collection of projections of the object of interest along different directions. The x-ray source controller 552, the rotational subsystem controller 560, the translational subsystem controller 562, and the x-ray detector controller 568 may all be integrated in a system controller 570, which may be coupled to the computer 550. In this exemplary embodiment, the system controller 570 may command operation of the imaging, data acquisition and preliminary data processing. It is contemplated that an embodiment in which the x-ray source controller 552, the rotational subsystem controller 560, the translational subsystem controller 562, and the x-ray detector controller 568 units are built of several sub-controllers performing parts of the tasks, or are integrated or grouped differently, may also be suitable. The system controller 570 may perform several tasks connected to the data collection and processing. The system controller 570 may control the x-ray power emitted by the x-ray source 502. It may also command the data acquisition done with the x-ray detector 518. System controller 570 may synchronize the movement generated by the rotational subsystem 510 and the translational subsystem 512 with data collection. It may also carry out various data processing and filtering tasks, it may adjust the dynamic ranges, or perform interleaving the digital image data. In this embodiment, the system controller 570 may include a general purpose or an application specific digital computer, with memory units for storing executable routines, settings, configuration parameters, collected data, and so forth. As described above, the system controller 570 may command the rotational subsystem 510 and the translational subsystem 512. The rotational subsystem 512 can rotate the x-ray source 502, the collimator 506 and the detector 518 around the object of interest. The translational subsystem 512 enables the linear movement of the x-ray source 502, the collimator 506 and the detector 518. Positioning of the x-ray source 502, collimator 506 and detector 518 might include a gantry, in which case the system controller 570 operates the movement of the gantry. While the system depicted in FIG. 5 illustrates a system that scans in a circular geometry, other geometries, such as for example linear geometry, may also be used. As will be appreciated by those skilled in the art, instead of utilizing moving components, the imaging system may use stationary source and/or detector. For illustrative purposes only, the imaging equipment may include “third generation” computed tomography scanners, “fourth generation” computed tomography scanners, “fifth generation” computed tomography scanners, or scanners with stationary detector. Other embodiments may include an extended x-ray source and a plurality of detectors, usually located on a ring. The detector ring in such case may include a plurality of distributed detector modules which may be in linear, multi-slice, or other detector arrangements. In the described embodiment different parts of the imaging equipment may communicate with each other by electric signals, but connections may be done by several other methods. Any method suitable of transferring the necessary information may be used (for example data could also be transferred by the means of optical cable, or wireless connection, and so forth). The computer 550 may typically be coupled to the system controller. The collected data may be transferred to computer 550, and stored in the digital memory of the computer 550, or any storage device which is part of, or coupled to the computer 550. Any type of memory capable of storing the collected data may be utilized. Moreover, the memory may be located local to the acquisition system, or may include remote components. The computer may be local to the imaging device, or may be remote from it, coupled to the imaging device through a network, or other remote connection. The network may also be connected to a remote client or database. Acquired data, imaging parameters, reconstructed images may be visualized by many methods. These methods may include, but are not limited to, visualizing on screen, printing on paper, slide, or film. The computer 550 may receive commands, settings and scanning parameters from an operator who controls the imaging system via input devices of the computer. The operator may observe the data or the reconstructed images, set input parameters, initiate imaging, and so forth. The operator may be local to the computer 550, or may be remote from it, coupled to the computer 550 through a network, or other remote connection. Some or all of the data processing described here may be performed remotely. In the exemplary embodiment of FIG. 5, the reconstructed image may reveal diagnostically important anatomic details about a patient, or visualize the internal structure of any object of interest penetrated by x-rays. The technique may be applied to three-dimensional and to two-dimensional acquisitions as well. FIG. 6 is a flowchart including exemplary steps for generating images reconstructed from statistical parameters describing the temporal distribution of the attenuated x-ray radiation collected by the detector using the system described in FIG. 5. In step 602 x-rays 504 may be generated by the x-ray source 502, shaped by collimator 506 in step 604, and passed through the object of interest 514 in step 606. In step 608 the portion of x-ray 516 which may pass through the object of interest 514 may be detected by the detector 518. In step 610 a plurality of measurements along at least one direction of detection may be collected. In step 612 at least one statistical parameter describing the temporal distribution of the collected plurality of measurements may be calculated. In step 614 the images representing the temporal distribution of x-ray measurements in the object of interest may be reconstructed. In step 614 images of the error of the statistical parameters may also be calculated. As will be appreciated by those skilled in the art, intensity readings (or other readings related to intensity) by the detector 518 may be subject to fluctuations. These fluctuations may come from two sources: random noise of the measurement, and real changes in the attenuation of the x-rays 508 inside the object of interest 514. Random noise may come from the Poisson shot noise of the detection, from electronic noise of the detector, or attached electronics parts, etc. Random noise contains no information about the object of interest 518. Fluctuations arising from real attenuation changes of the object of interest 514 may carry important information about the movements of the object of interest. FIG. 7 illustrates how the distribution of the random noise and distribution of the fluctuations of the object of interest may determine the distribution of the detector readings. Fluctuations originating in the object of interest may be separated from random noise, and a new type of image representing the fluctuations of the object may thus be created. The described exemplary embodiment of FIG. 5 may separate random noise which may be dominated by Poisson shot noise from attenuation fluctuations which may follow normal distribution. Other embodiments may represent the fluctuations of the measured intensities without separating the random noise from fluctuations reflecting attenuation changes. These images may also contain the information about the attenuation fluctuations. In many cases such images may be just as usable as those images which were obtained after the separation of the random fluctuations and those originating in the object of interest. It is contemplated, however, that those images which are obtained after extraction of the random noise from the fluctuations may be of a substantially higher quality. The above distributions may be considered in this exemplary embodiment for the following reasons. The sum of several random variables with finite means and variances approaches normal distribution as the number of variables increases. Because of this, normal distribution may be commonly encountered in biological and physical systems. Poisson noise is typical for particle counting measurements. Less frequently than the distributions taken in account in this embodiment, other distributions may also be of interest. The actual distributions of the random noise and attenuation fluctuations may depend on details of the embodiment, type of penetrating radiation, object of interest, and so forth. Based on the present disclosure, embodiments in which the separated random noise and/or attenuation fluctuations follow other distributions may also be constructed by the person skilled in the art. The attenuation of x-rays in an absorber may be described by exponential formula (1):I=I0·Exp[−D] (8)where I denotes the expected value of the number of x-ray photons after the absorber, I0 denotes the expected value of the number of x-ray photons before the absorber, D denotes the x-ray density of the absorber. Exp[ . . . ] denotes the e-based exponential function. If the x-ray beam crosses several absorbers with x-ray densities Di each, the combined density D of the series of absorbers may be calculated as the sum of the density of the individual parts:D=ΣiDi (9)where i may be 1, 2, 3, . . . indexing the absorbers, and μi represents summation for all i-s. The densities Di may represent the x-ray densities of volume elements (voxels) of an object of interest. If the densities Di vary following normal distributions with expected values E(Di) and variances Var(Di), then D will also follow a normal distribution with an expected value E(D) and variance Var(D). E(D) and variance Var(D) determined by the sum of the expected values and the sum of the variances of the Di densities, respectively:E(D)=ΣiE(Di), (10)Var(D)=Σi Var(Di). (11) To determine experimentally the x-ray density D of an object of interest, the x-ray intensities I may be measured. The result of the intensity measurement may typically be a photon number reading: k. Making a plurality of photon number detections may reveal that the photon numbers k fluctuate. These fluctuations may come from two sources: random noise of the measurement and real changes in the x-ray density D. If the x-ray density D follows normal distribution, the intensity I will follow lognormal distribution. In this embodiment it will be assumed that the random noise of the detection is determined by the Poisson shot noise of photon counting. Taking into account both sources of fluctuations the following expressions may be obtained for the expected value and variance of the detected photon numbers k:E(k)=I0·Exp[Var(D)/2−E(D)], (12)Var(k)=I0·Exp[Var(D)/2−2·E(D)]·(Exp[D]−I0·Exp[0.5·Var(D)]+I0·Exp[1.5·Var(D)]) (13) If the expected value E(k) and variance Var(k) of the photon counts k are determined experimentally, the expected value E(D) and the variance Var(D) of the density D may be calculated by solving the above equations:E(D)=Log[I0·Sqrt[Var(k)−E(k)+E(k)2]/E(k)2], (14)Var(D)=2·Log[Sqrt[Var(k)−E(k)+E(k)2]/E(k)] (15)where Log[ . . . ] denotes the natural (e-based) logarithm, Sqrt[ . . . ] denotes the square root function. An estimation of the expected value E(k) of the photon number k alone may be used to determine the density D, only if the variance of D is zero. If the x-ray density D varies, both the expected value E(D) and the variance Var(D) of the density D may be calculated from the expected value E(k) and variance Var(k) of the photon counts k. Depending on the fluctuations, an x-ray density determined from the expected value E(k) of the photon numbers may differ significantly from the expected value E(D) of the density. The presented embodiment thus may yield a more accurate image of the object of interest than methods of the prior art which determine an estimation only for the expected value of the photon counts. The expected value E(k) and variance Var(k) of the photon counts are parameters that describe the theoretical distribution of the photon counts k. These parameters can not be determined directly, but they can be estimated from measurements. The presented embodiment may make a plurality (n) of photon count readings and may calculate an estimation for both the expected value E(k) and variance Var(k) of the photon counts k. The estimations for the expected value E(k) and for the variance Var(k) may be used to calculate an estimation of the expected value E(D) and the variance Var(D) of the density D. Estimating the expected value E(D) and the variance Var(D) for a plurality of projection directions may be used to reconstruct three dimensional images of the expected value E(Di) and variance Var(Di) of the x-ray density of the object of interest. FIG. 8 includes projection images of moving cogged wheels of a clock. These images were recorded along a fixed projection angle using the system described in FIG. 5. FIG. 8A illustrates the average density image E(D). FIG. 8B shows the variance image Var(D). At first sight, in FIG. 8B the fastest wheel 802 moving the whole mechanics of the clock may be seen. FIG. 8C magnifies a smaller part of the variance image Var(D) to illustrate the dynamic range and the quality of the image. Since the mechanics moving the second 804, minute 806, and hour 808 fingers move at different speed, the dynamic range of these movements is broad. FIG. 9 includes projection images of the chest of a living frog. These images were recorded along a fixed projection angle using the system described in FIG. 5. FIG. 9A illustrates the average density image E(D) of the frog. FIG. 9B shows the variance image Var(D) of the same part of the frog. Frogs have very weak soft tissue contrast, and the average density image practically only shows the bones. In the variance image the lung (902), the heart (904) and the aorta (906) are highlighted. The two valves (908) of the frog's heart appear as two bright short lines. The back of the tongue or the throat (910) of the frog also moves as it is breathing. FIG. 10 includes projection images of that part of a snake that contains the heart. These images were recorded along a fixed projection angle using the system described in FIG. 5. FIG. 10A illustrates the average density image E(D) of part of the snake. FIG. 10B shows the variance image Var(D) of the same part of the animal. While the average image mainly shows the bones, the elongated heart (1010) of the snake is visualised in the variance image. In many applications it may be useful to determine the error of the reconstructed images of the expected value E(Di) and variance Var(Di) of the voxel x-ray densities. Error images may hold important information, including, without limitation, for optimization of data acquisition, for efficient image analysis, denoising, or automatic shape recognition. The images representing E(Di) and Var(Di) were reconstructed from the expected value E(k) and the variance Var(k) which were estimated from the photon numbers. To estimate the error of the images E(Di) and Var(Di), first it may be needed to give an estimation for the error of the expected value E(k) and the error of the variance Var(k) of the detected photon numbers. To estimate the error of E(k) and Var(k) any statistical method (such as jackknifing, bootstrapping, and so forth) may be used which allows a reasonably accurate guess of the errors. For normal distributions the error of the estimation of the expected value and of the variance can be easily calculated:Err(E(k))=Var(k)/Sqrt[n], (16)Err(Var(k))=0.71·Var(k)/Sqrt[n], (17)where Err(E(k)) represents the error of the estimation of the expected value E(k), Err(Var(k)) represents the error of the estimation of the variance Var(k), n denotes the number of the photon count measurements. Although the above error estimations were derived for normal distributions, the estimation method is robust, and the error estimations calculated based on the above formula may give an adequate estimation of the error of E(k) and Var(k) for other distributions as well. The presented exemplary embodiment, may use the above formula for the estimation of the errors Err(E(k)) and Err(Var(k)). The expressions for the errors of the expected value E(D) and the variance Var(D) of the density D may be derived from the expressions for E(D) and Var(D). After simplifying the expressions, Err(E(D)) and Err(Var(D)) may be calculated from the errors of the expected value E(k) and variance Var(k) of the photon counts k in the following way:Err(E(D))=(E(k)^2−1.855·E(k)+2·Var(k))·Var(k)/(Sqrt[n]·E(k)·(E(k)^2−E(k)+Var(k))), (18)Err(Var(D))=(1.71·E(k)−2·Var(k))·Var(k)/(Sqrt[n]·E(k)·(E(k)^2−E(k)+Var(k))). (19) Other embodiments may use other statistical methods such as jackknifing or bootstrapping which may give a better estimation of the errors, but may also be more computation-intensive. As described above, the presented embodiment may use a plurality of detector photon count readings k to calculate an estimation for (1) the expected value E(D), (2) the variance Var(D), (3) the error of the expected value Err(E(D)), and (4) the error of the variance Err(Var(D)) of the density D. These four quantities may be determined for a plurality of projection angles, which may allow reconstructing four different three dimensional images of the object of interest: the mean x-ray density image, the x-ray density variance (fluctuation) image, the image representing the error of the x-ray density variance (fluctuation), and image representing the error of the mean x-ray density. The exemplary embodiment described herein may use weighted filtered back projection to determine the above images. Several other method exist that may be used to reconstruct three dimensional images from their projections. Other embodiments may use other reconstruction methods. In accordance with the presented exemplary embodiment, the expected value E(D), the variance Var(D), the square of the error of the expected value Err(E(D)), and the square of the error of the variance Err(Var(D)) may be processed by a three dimensional reconstruction algorithm. The contemplated algorithm may include a series of weighting, filtering and back projection steps for each projection measurement over the reconstruction volume. Weighting of the projection data may be performed by an element-by-element multiplication with an array containing the weighting factors. The filtering step may use a series of convolutions to decorrelate image data points. In the back projection step the projection measurements may be added to all voxels along the projection line. Different x-ray beam geometries may be taken into account through the use of weighting factors in the back projection. The exemplary embodiment may process the square of the errors Err(E(D)) and Err(Var(D)) obtained from the projections, thus an image that represents the square of the errors in the voxels may be obtained. To represent the errors, a square root may be calculated voxel by voxel. The exemplary embodiment described here, thus may calculate the expected value E(Di), the variance Var(Di), the error of the expected value Err(E(Di)), and the error of the variance Err(Var(Di)) for the Di densities of the volume elements of the object of interest. The expected value image reconstructed using the presented embodiment may be more accurate than images obtained by previous techniques. This, in many cases may be an important advancement itself. The variance image may reflect the fluctuations in the x-ray absorbance, a new modality that may be used for the visualization of movements inside the object of study. The new modality may bring new contrast schemes as well, which may allow the visualization of structures which were not previously resolvable. The more accurate measurement-based reconstruction of the error of the expected value and variance images may be very useful in many cases. These error images may be used in the optimization of image acquisition parameters, decision making about the reacquisition of images of insufficient quality, diagnostic decision making, computer aided detection, identification of regions of interest, digital image processing, image noise reduction, averaging of images, and so forth. As will be appreciated by those skilled in the art, the exemplary embodiments of the measuring devices and methods described above may involve extensive computer calculations. These calculations may include a listing of computer code containing executable instructions. This listing (program) may be embodied in any computer-readable information storage device, for use by or in connection with a system which can execute the instructions. The processing may be done local to the acquisition or local to the storage of the acquired data. Alternatively, some or all the calculations may be performed remotely. The computer-readable information storage device may be any means that can contain, store, communicate, propagate, transmit or transport information. The usable devices may use electronic, magnetic, optical, electromagnetic, mechanic, nanotechnology-based media, but are not limited to these. The presented embodiments are described here as exemplary systems only. It should be noted that the presented systems and methods are in no way limited to the actual arrangements described, or the use of x-radiation or electron beams. Other embodiments can be envisioned for acquiring and processing the attenuation of penetrating radiation to obtain at least one of the following images: the mean attenuation image, its error, the image of the deviation of the attenuation, and its error. Glossary of Technical Terms Bootstrapping—Bootstrapping is a general purpose re-sampling method for statistical inference. Expected value—The expected value (also called mean) of a random variable is the integral of the random variable with respect to its probability measure. For discrete variables this is the probability-weighted sum of the possible values. Fifth generation CT scanner—A fifth generation computed tomography scanner is a CT scanner which uses a stationary detector ring and an X-ray tube moving on a circular path outside the detector ring. Fourth generation CT scanner—A fourth generation computed tomography scanner is a CT scanner which uses a stationary detector ring and an X-ray tube moving on a circular path inside the detector ring. Jackknifing—Jackknifing is a statistical method that calculates standard error of a statistic estimate by systematically recomputing multiple times the statistic estimate leaving out one observation from the sample set. Projection—A projection may be defined as a shadow image of the attenuation of the object of interest recorded under one single angle of view. Scan—A scan comprises of a set of projections recorded under different angles of view which allow the reconstruction of the internal structure of at least a part of the object of interest. Shock wave—A shock wave is an abrupt propagating disturbance. Shot noise—Shot noise refers to the statistical fluctuations of counting a finite number of particles that carry energy (photons, electrons, etc.). Third generation CT scanner—A third generation computed tomography scanner is a CT scanner in which a fan-beam projection allows the simultaneous measurement of the entire patient cross-section. Variance—The variance of a random variable is the expected value of the square of the deviation of that variable from its expected value. Variance measures the amount of variation within the values of the variable. x-ray density—The x-ray density (also called x-ray absorbance) of an absorber is defined as D=Log[I0/I], where I is the x-ray intensity that has passed through the absorber, I0 is the intensity of the x-ray before it enters the absorber, Log[ . . . ] denotes the natural (e-base) logarithm. Alternatively, density can also be defined as D=Log10[I0/I], where Log10[ . . . ], denotes the 10-base logarithm function.
046541926	description	DETAILED DESCRIPTION OF THE INVENTION The instant invention is an apparatus for releasably supporting a safety rod, said apparatus being actuated automatically by a pre-determined increase in temperature. The device includes a bimetallic component which comprises two intimately bonded metals having different thermal coefficients of expansion. An increase in the temperature of the component will cause a deflection toward the side of the component having the lower expansion coefficient. If one end of the component is held fast, the free end will deflect from its original configuration. When the temperature of the component returns to normal, the component will resume its original configuration. The instant invention is readily understood by reference to FIGS. 1-3 which show safety rod upper adapter 10 housed within safety rod drive shaft 12. Coolant flows upwardly from the safety rod (not shown) through the hollow interior 14 of upper adapter 10 and out into the reactor vessel through ports 16 in upper adapter 10 and ports 18 in drive shaft 12. Upper adapter 10 is provided with protruding retention shoulder 19. In the embodiment shown in FIGS. 1-3 bimetallic member 20 is substantially cylindrical. Inner layer 22 has a higher thermal coefficient of expansion than outer layer 24. As shown in FIGS. 2 and 3, member 20 is provided with split 25 in substantially the axial direction. Inner layer 22 is provided with ledge 27 which engages retention shoulder 19 of upper adapter 10, thereby supporting the safety rod. The inner edge 28 of ledge 27 defines a circle that is eccentric with the circle defined by the circumference of member 20. Thus ledge 27 is widest at split 25 and narrowest at the point diammetrically opposed thereto. This is most easily seen in FIG. 3. Outer layer 24 is provided with collar 29 which rests on shelf 13 of drive shaft 12 to provide support for member 20. Coolant flowing through ports 16 in upper adapter 10 comes in intimate contact with bimetallic member 20, so that the temperature of member 20 tends to be at or near the temperature of the flowing coolant. In the event of a thermal excursion in the nuclear reactor, the temperature of the coolant may rise about 200.degree. F.; for example, a normal coolant outlet temperature of about 950.degree.-1000.degree. F. may rise to about 1150.degree.-1200.degree. F. The gain in temperature of the flowing coolant will be experienced by bimetallic member 20. Because the thermal coefficient of expansion of inner layer 22 is greater than that of outer layer 24, inner layer 22 will expand more than outer layer 24. This will cause bimetallic member 20 to deform by "opening" at split 25. The term "opening" as used here means that the two halves of bimetallic member 20 defined by split 25 are deflected from one another in a jaw-like manner such that split 25 widens. The extent of the opening will be much greater than that which would occur with simple mono-metallic thermal expansion. It may be seen that the greatest amount of deformation occurs at split 25 where ledge 27 is widest and almost no deformation occurs at the point diametrically opposed thereto where ledge 27 is narrowest. When the temperature is increased by at least a pre-determined amount, the deformation is sufficient such that the opening movement of bimetallic member 20 disengages ledge 27 from retention shoulder 19, thereby releasing the safety rod into the reactor core in automatic response to the thermal excursion. Bimetallic member 20 is provided with spine 30 opposite split 25. Spine 30 is secured to drive shaft 12 by known fastening means such as screws 32. Spine 30 provides a pivot point for the jaw-like opening action of member 20. After the reactor has cooled from its thermal excursion and bimetallic member 20 has resumed its normal configuration it may be easily reengaged with upper adapter 10. This is accomplished while the safety rod with upper adapter 10 is still in its lowered position. Drive shaft 12 supporting member 20 therein is forced downwardly over upper adapter 10. Upper conical portion 15 of upper adapter 10 forces bimetallic member 20 into a slightly open position. As drive shaft 12 moves downward, it brings bimetallic member 20 down along portion 11 of upper adapter 10, with ledge 27 following the contour of said portion until it is driven around and under retention shoulder 19. When member 20 reaches its normal position along upper adapter 10, the opening force is relieved and ledge 27 of member 20 simply snaps into place beneath retention shoulder 19. Thus the instant invention is uniquely simple to reengage. An alternative embodiment of the invention is illustrated in FIGS. 4 and 5. In this embodiment, bimetallic means 120 comprises a plurality of bimetallic strips 121, each strip 121 having an inner layer 122 and an outer layer 124, each inner layer 122 having a larger thermal coefficient of expansion than the corresponding outer layer 124. In the particular embodiment shown, four such strips are provided. The strips 121 are parallel to upper adapter 110, and are suspended from drive shaft 112 by fastening means such as screws 132. The inner layer 122 of each strip 121 is provided with a supporting ledge 127 which engages upper adapter retention shoulder 119, so that the plurality of strips 121 together support upper adapter 110. Coolant flowing upwardly past the safety rod (not shown), through interior 114 of upper adapter 110 and out of the ports 116 comes in intimate contact with bimetallic strips 121. In the event of a thermal excursion in the reactor, the temperature gain of the coolant will be experienced by bimetallic strips 121. The greater expansion of inner layers 122 relative to outer layers 124 causes bimetallic strips 121 to deform by deflecting away from upper adapter 110 near the region of engagement. At a predetermined increase in temperature, the deflection is sufficient such that support ledges 127 become disengaged from retention shoulder 119, thereby releasing the safety rod into the reactor core in automatic response to the thermal excursion. It may be seen that this embodiment of the invention can reengage the upper adapter in a manner analogous to that of the substantially cylindrical embodiment, that is, by pushing the drive shaft down over the upper adapter until ledges 127 snap into position under retention shoulder 119. The instant invention is particularly well suited for use in liquid metal fast breeder reactors (LMFBR). In these reactors the normal coolant outlet temperature is about 950.degree.-1000.degree. F., so the pre-determined automatic release temperature for a thermal excursion should be about 1150.degree.-1200.degree. F. A typical rod assembly is about 18' long and about 6" across the flats of a hexagonal cross-section; the diameter of the upper adapter is typically somewhat narrower. For these dimensions, the overall size of the substantially cylindrical embodiment may be about 12" long and about 5.5" in diameter. The inner layer may be an austenitic stainless steel which has a relatively high thermal coefficient of expansion, and the outer layer may be a high chrome steel having a lower thermal expansion coefficient. For these materials, satisfactory results will be obtained if each layer is about 0.050"-0.100" thick and if the device has a free length of about 4.0"-8.0". The bimetallic components can be manufactured by known methods such as the explosive bonding process. It would be desirable for the non-stressed state of the bimetallic components to be about 1000.degree. F. The invention may be modified within the scope of the above teachings. For example, instead of using a retention shoulder and a supporting ledge, the upper adapter and the bimetallic components may be provided with corresponding ratchet grooves. The invention may also be adapted to different temperatures, may be enlarged or reduced in size, and may be made of different materials, all within the intended scope of the invention. The foregoing description is not intended to limit the invention to the precise forms disclosed. The embodiment was chosen and described in order to best explain the principles of the invention and its practical application.
050230441	abstract	An assembly for controlling the release of neutrons in a nuclear reactor having the core split into two halves. A disk assembly formed from at least two circular disks is positioned substantially at the center of and coaxially with the core halves. Each disk is machined with an identical surface hole pattern such that rotation of one disk relative to the other causes the hole pattern to open or close. The disks may be formed from neutron absorbing material or moderator material. The holes may be provided with fissile material inserts to enhance reactivity when in the open position. A drive motor mounted adjacent the reactor and drive shaft operatively engaged between the drive motor and disks is used to rotate the disks.
	abstract	A system and method for utilizing a radiation source for irradiating a product, the system including an radiation reflector comprised of a low Z, high density material. The reflector is positioned to receive radiation penetrating and exiting the product, and the reflector reflects the radiation back to the product to provide additional irradiation energy to the product.
	claims	1. A system comprising:an injection boring; anda gravity fracture located below an exit point of the injection boring and filled with a fluid being denser than a rock formation into which the fluid is to be disposed so as to cause the rock formation to gravity fracture, the fluid propagating downward in the gravity fracture as the gravity fracture propagates downward. 2. A system according to claim 1 wherein the fluid has a density of at least 3.0 g/cm3. 3. A system according to claim 1 wherein the fluid is a slurry. 4. A system according to claim 3 further comprising the slurry including a solid material which is blended with at least one waste. 5. A system according to claim 4 wherein the solid material is a metal. 6. A system according to claim 5 wherein the metal is selected from the group consisting of bismuth, iron, lead, and copper. 7. A system according to claim 5 wherein the solid material contains one or more radionuclides. 8. A system according to claim 3 wherein a liquid component of the slurry is a metal having a melting temperature less than a temperature at a bottom end of an injection boring from which the fluid exits into the rock formation. 9. A system according to claim 8 wherein the metal is selected from the group consisting of mercury, woods metal, indalloy 15, and gallium. 10. A system according to claim 1 further comprising the fluid including a liquid. 11. A system according to claim 10 wherein the liquid includes at least a portion thereof selected from the group consisting of a cross-linked polymer gel and a hydrated clay slurry. 12. A system according to claim 10 wherein the liquid is a metal having a melting temperature less than a temperature at a bottom end of an injection boring from which the fluid exits into the rock formation. 13. A system according to claim 10 wherein the liquid is a metal selected from the group consisting of mercury, woods metal, indalloy 15, and gallium. 14. A system according to claim 1 further comprising the fluid including a solid material. 15. A system according to claim 14 wherein the solid material is a metal. 16. A system according to claim 15 wherein the metal is selected from the group consisting of bismuth, iron, lead, and copper. 17. A system according to claim 14 wherein the solid material contains one or more radionuclides. 18. A system according to claim 1 further comprising the fluid including a waste material to be disposed of. 19. A system according to claim 18 wherein the waste material is a hazardous waste. 20. A system according to claim 19 wherein the waste material is a radioactive waste. 21. A system comprising:an injection boring arranged to receive a fluid containing a waste material, the fluid being denser than a rock formation into which the fluid is to be disposed; anda gravity fracture located below an exit point of the injection boring, the fluid propagating downward in the gravity fracture as the gravity fracture propagates downward. 22. A system according to claim 21 wherein the fluid is a slurry including a solid material blended with the waste material.
	description	This application claims priority, under Section 371 and/or as a continuation under Section 120, to PCT Application No. PCT/IB2011/003330, filed on Jun. 2, 2011. The present invention generally relates to systems, methods and containers for storing hazardous waste material and, more particularly, to systems, methods and containers for storing nuclear waste material. Despite a proliferation of systems for handling and storing hazardous waste materials, prior art systems are still unable to effectively confine and control the unnecessary spread of hazardous waste contamination to areas remotely located from the hazardous waste material filling stations. Therefore, an urgent need exists for hazardous waste processing/storing systems that effectively minimize and/or eliminate unnecessary hazardous material contamination. A modularized process flow facility plan in accordance with the present invention may be implemented in numerous ways, including as a process, an apparatus, a system, and a composition of matter. In an exemplary system implementation of in accordance with the present invention, a modularized system for processing, storing and/or disposing of a hazardous waste material, is provided. Said modularized system comprising a plurality of cells for processing and/or storing said hazardous waste material, each cell including at least one respective area for manipulating a hazardous waste container, each cell being isolated from all of the other cells, and each cell being held at a predetermined negative pressure or range of pressures relative to all of the other cells. The modularized system may be configured in numerous ways depending on the spatial arrangement of the plurality of cells. The plurality of cells may be arranged in numerous ways, including as a single row of contiguous cells or as a plurality of rows of contiguous cells. Accordingly, in one embodiment, the modularized system for storing hazardous waste material comprises (a) a container configured to scalingly contain hazardous waste material; (b) a first cell, the first cell comprising a first area for manipulating the container; and (c) a second cell, the second cell comprising a second area for manipulating the container, the second cell being isolated from the first cell, the first cell held at a first pressure P1 and the second cell held at a second pressure P2, the first pressure P1 being less than the second pressure P2. In one embodiment of the system for processing and/or storing said hazardous waste material, the first cell comprises a filling station. In a further embodiment, the filling station includes (i) a blender configured to mix the hazardous waste material with additives; (ii) a hopper coupled to the blender; and (iii) a fill nozzle coupled to the hopper and configured to transfer the hazardous waste material and additive mixture into the container. In one embodiment of an exemplary system for processing and/or storing said hazardous waste material in accordance with the present invention, the first cell does not exchange air with the second cell while at least the container is being filled by the filling station. In another embodiment, the filling station includes an off-gas sub-system having a vacuum nozzle configured to couple to the container. In yet another embodiment, the second cell comprises a baking and sealing station. In a further embodiment, the baking and sealing station is configured to seal a filling port of the container. In another embodiment, the baking and sealing station includes an orbital welder. In a further embodiment, the baking and sealing station includes a welding station, a bake-out furnace and an off-gas system having a vacuum nozzle configured to couple to the container. In another exemplary implementation, the modularized system for processing, storing and/or disposing, of a hazardous waste material comprises (a) a first cell, the first cell comprising a first area for manipulating the container; (b) a second cell, the second cell comprising a second area for manipulating the container, the second cell being isolated from the first cell, the first cell held at a first pressure P1 and the second cell held at a second pressure P2, the first pressure P1 being less than the second pressure P2; and (c) a third cell, the third cell being isolated from the first cell and the second cell, the second cell and third cell configured to allow the container to be transferred from the second cell to the third cell. In one embodiment, the first cell is held at a first negative pressure P1, the second cell is held at a second negative pressure P2 and the third cell is held at a third negative pressure P3, the first negative pressure P1 being greater than the second negative pressure P2 and the third negative pressure 23 and the second negative pressure 22 being greater than the third negative pressure P3. In another embodiment, the third cell comprises a hot isostatic pressing station. In another exemplary implementation of the modularized system for processing, storing and/or disposing of a hazardous waste material, the modularized system comprises (a) a first cell, the first cell comprising a first area for manipulating the container; (h) a second cell, the second cell comprising a second area for manipulating the container, the second cell being isolated from the first cell, the first cell held at a first pressure P1 and the second cell held at a second pressure 22, the first pressure P1 being less than the second pressure P2; (c) a third cell, the third cell being isolated from the first cell and the second cell the second cell and third cell configured to allow the container to be transferred from the second cell to the third cell; and (d) a fourth cell, the fourth cell being isolated from the first cell, the second cell and the third cell, the third cell and fourth cell configured to allow the container to be transferred from the third cell to the fourth cell. In one embodiment, the first cell is held at a first negative pressure P1, the second cell is held at a second negative pressure P2, the third cell is held at a third negative pressure P3, and the fourth cell is held at a fourth negative pressure P4, the first negative pressure P1 being greater than the second negative pressure P2, the third negative pressure P3 and the fourth pressure P4, the second negative pressure P2 being greater than the third negative pressure P3 and the fourth negative pressure P4, and the third negative pressure P3 being greater than the fourth negative pressure P4. In another embodiment, the fourth cell comprises a cooling and packing station. In another exemplary modularized system for processing, storing and/or disposing of a hazardous waste material in accordance with the present invention, the modularized system further comprises an interlock, the interlock coupling the first cell to the second cell and configured to allow the container to be transferred from the first cell to the second cell while maintaining at least one seal between the first cell and the second cell. In one embodiment, the interlock includes decontamination equipment. In yet another exemplary modularized system, the modularized system further comprises a recycle line configured to add secondary hazardous waste into the container. In another embodiment, the secondary hazardous waste includes mercury evacuated from previous containers. In yet another embodiment, the secondary hazardous waste includes an evacuation filter used during evacuation of previous containers. In an embodiment, the modularized system for processing, storing and/or disposing of a hazardous waste material in accordance with the present invention, the plurality of cells may have any suitable spatial arrangement, including a lateral arrangement of cells, a vertical arrangement of cells or a combination of laterally arranged cells and vertical arranged cells. In one embodiment, the modularized system comprises a plurality of cells spatially arranged in a single row of contiguous cells, wherein each cell is isolated from an adjacent cell. In another embodiment, the plurality of cells may be spatially arranged in a single row of contiguous cells, wherein each cell may be isolated from an adjacent cell by at least one common side wall. In another embodiment, the plurality of cells may be arranged vertically in space in single column of contiguous cells, wherein each cell is isolated from an adjacent cell by at least one common wall. In yet another embodiment, the plurality of cells may be spatially arranged in a plurality of rows of contiguous cells. In one embodiment, the modularized system for processing, storing and/or disposing of a hazardous waste material in accordance with the present invention comprises a first cell and a second cell, and a third cell, the first cell being adjacent the second cell and contiguous therewith, and the third cell being adjacent the third cell and being contiguous therewith, wherein said first cell, the second cell and the third cell are spatially arranged in a single row of cells. The modular system in accordance with the present invention may be used to process liquid or solid hazardous waste material. The hazardous waste material may be a radioactive waste material. A radioactive liquid waste may include aqueous wastes resulting from the operation of a first cycle solvent extraction system, and/or the concentrated wastes from subsequent extraction cycles in a facility for reprocessing irradiated nuclear reactor fuels. These wastes may contain virtually all of the nonvolatile fission products, and/or detectable concentrations of uranium and plutonium originating from spent fuels, and/or all actinides formed by transmutation of the uranium and plutonium as normally produced in a nuclear reactor. In one embodiment, the hazardous waste material includes calcined material. There is disclosed herein a system for storing hazardous waste material, the system comprising: a container configured to sealingly contain hazardous waste material; a first cell, the first cell comprising a first area for manipulating the container; and a second cell, the second cell comprising a second area for manipulating the container, the second cell being isolated from the first cell, the first cell held at a first pressure and the second cell held at a second pressure, the first pressure being less than the second pressure. Preferably, the first cell comprises a filling station. Preferably, the filling station includes: a blender configured to mix the hazardous waste material with additives; a hopper coupled to the blender; and a fill nozzle coupled to the hopper and configured to transfer the hazardous waste material and additive mixture into the container. Preferably, the hazardous waste material includes calcined material. Preferably, the first cell does not exchange air with the second cell while at least the container is being filled by the filling station. Preferably, the filling station includes: an off-gas sub-system having a vacuum nozzle configured to couple to the container. Preferably, the second cell comprises a baking and sealing station. Preferably, the baking and sealing station is configured to seal a filling port of the container. Preferably, the baking and sealing station includes an orbital welder. Preferably, the baking and sealing station includes a welding station, a bake-out furnace and an off-gas system having a vacuum nozzle configured to couple to the container. The system of any of the preceding claims further comprising: a third cell, the third cell being isolated from the first cell and the second cell, the second cell and third cell configured to allow the container to be transferred from the second cell to the third cell. Preferably, the third cell comprises a hot isostatic pressing station. Preferably, the third cell is held at a third pressure, the third pressure being greater than the second pressure. The system of any of the preceding claims further comprising: a fourth cell, the fourth cell being isolated from the first cell, the second cell and the third cell, the third cell and fourth cell configured to allow the container to be transferred from the third cell to the fourth cell. Preferably, the fourth cell comprises a cooling and packing station. Preferably, the fourth cell is held at a fourth pressure, the fourth pressure being greater than the third pressure. The system of any of the preceding claims further comprising: an interlock, the interlock coupling the first cell to the second cell and configured to allow the container to be transferred from the first cell to the second cell while maintaining at least one seal between the first cell and the second cell. Preferably, the interlock includes decontamination equipment. The system of any of the preceding claims further comprising: a recycle line configured to add secondary hazardous waste into the container. Preferably, the secondary hazardous waste includes mercury evacuated from previous containers. Preferably, the secondary hazardous waste includes an evacuation filter used during evacuation of previous containers. Reference will now be made in detail to the various embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings FIGS. 2-17. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. Nuclear waste, such as radioactive calcined material, can be immobilized in a container that allows the waste to be safely transported in a process known as hot isostatic pressing (HIP). In general, this process involves combining the waste material in particulate or powdered form with certain minerals and subjecting the mixture to high temperature and high pressure to cause compaction of the material. In some instances, the HIP process produces a glass-ceramic waste form that contains several natural minerals that together incorporate into their crystal structures nearly all of the elements present in HLW calcined material. The main minerals in the glass-ceramic can include, for example, hollandite (BaAl2Ti6O16), zirconolite (CaZrTi2O7), and perovskite (CaTiO3). Zirconolite and perovskite are the major hosts for long-lived actinides, such as plutonium, though perovskite principally immobilizes strontium and barium. Hollandite principally immobilizes cesium, along with potassiume, rubidium, and barium. Treating radioactive calcined material with the HIP process involves, for example, filling a container with the calcined material and minerals. The filled container is evacuated and sealed, then placed into a HIP furnace, such as an insulated resistance-heated furnace, which is surrounded by a pressure vessel. The vessel is then closed, heated, and pressurized. The pressure is applied isostatically, for example, via argon gas, which, at pressure, also is an efficient conductor of heat. The combined effect of heat and pressure consolidates and immobilizes the waste into a dense monolithic glass-ceramic sealed within the container. FIGS. 1A and 1B respectively show an example container, generally designated 100, before and after HIP processing. Container 100 has a body 110 defining an interior volume for containing waste material. Body 110 includes sections 112 each having a first diameter and a section 114 having a second diameter that may be less than the first diameter. Container 100 further has a lid 120 positioned at a top end of body 110 and a tube 140 extending from lid 120 which communicates with the interior volume of body 110. The interior volume of body 110 is filled with waste material is tube 140. Following hot isostatic pressing, as shown in FIG. 1B, the volume of body 110 is substantially reduced and container 100 is then sealed. Typically, tube 140 is crimped, cut, and welded by linear seam welding. One drawback in such a process is that cutting of tube 140 can create secondary waste as the removed portion of tube 140 may contain amounts of residual waste material which must then be disposed of in a proper manner. Moreover, the tools used for cutting tube 140 may be exposed to the residual waste material and/or require regular maintenance or replacement due to wear. Also, this system requires complex mechanical or hydraulic systems to be in the hot cell (radioactive environment) near the can to be sealed reducing the life of seals on hydraulic rams and the equipment is bulky taking up additional space in the hot cell. It is therefore desirable to have systems, methods, filling equipment and containers for storing hazardous waste material that can avoid one or more of these drawbacks. FIG. 2 schematically represents an exemplary process flow 200 used to dispose of nuclear waste, such as calcined material, in accordance with the present invention. Process 200 may be performed using a modular system 400, exemplary embodiments of which are illustrated in subsequent figures, wherein the hazardous waste is processed or moved in a series of isolated cells. Modular system 400 may be referred to as including the “hot cell” or “hot cells”, in some embodiments, each cell is isolated from the outside environment and other cells such that any spillage of hazardous waste may be contained within the cell in which the spill occurred. Modular system 400 in accordance with the present invention may be used to process liquid or solid hazardous waste material. The hazardous waste material may be a radioactive waste material. A radioactive liquid waste may include aqueous wastes resulting from the operation of as first cycle solvent extraction system, and/or the concentrated wastes from subsequent extraction cycles in a facility for reprocessing irradiated nuclear reactor fuels. These waste materials may contain virtually all of the nonvolatile fission products, and/or detectable concentrations of uranium and plutonium originating from spent fuels, and/or all actinides formed by transmutation of the uranium and plutonium as normally produced in a nuclear reactor. In one embodiment, the hazardous waste material includes calcined material. Modular system 400 may be divided into two or more cells. In one embodiment, modular system 400 includes at least four separate cells. In one embodiment, modular system 400 includes four separate cells. In one such embodiment, the series of cells include a first cell 217, which may be a filling cell, a second cell 218, which may be a bake-out and vacuum sealing cell, a third cell 232 which may be a process cell, and a fourth cell 230 which may be a cooling and packaging cell, each of which will be discussed in more detail below. In one embodiment, first cell 217 includes a feed blender 212 configured to mix a hazardous waste material with one or more additives. In one embodiment, a container feed hopper 214 is coupled to feed blender 212. In one embodiment, container feed hopper 214 is coupled with a fill system to transfer the hazardous waste material and additive mixture into container 216. In some embodiments, calcined material is transferred from a surge tank 205 to a calcined material receipt hopper 207 configured to supply feed blender 212. In some embodiments, additives are supplied to feed blender 212 from hopper 210. In some embodiments, the additives are transferred to hopper 210 from tank 201. After being filled, container 216 is removed from first cell 217 and transferred to second cell 218 where bake-out and vacuum sealing steps take place. In some embodiments, the bake-out process includes heating container 216 in a furnace 290 to remove excess water, for example, at a temperature of about 400° C. to about 500° C. In some embodiments, off-gas is removed from container 216 during the bake-out process and routed through line 206, which may include one or more filters 204 or traps 219 to remove particulates or other materials. In further embodiments, a vacuum is established in container 216 during the bake-out process and container 216 is sealed to maintain the vacuum. After the bake-out and sealing steps, according to some embodiments, container 216 is transferred to third cell 232 where the container 216 is subjected to hot isostatic pressing or RIP, for example, at elevated temperature of 1000° C. 1250° C. and elevated argon pressure supplied from a compressor 234 and argon source 236. In some embodiments, hot isostatic pressing results in compaction of container 216 and the waste material contained therein. After the hot isostatic pressing, according to some embodiments, container 216 is transferred to fourth cell 230 for cooling and/or packaging for subsequent loading 203 for transport and storage. Modular system 400 may be configured in numerous ways depending on the spatial arrangement of the plurality of cells. In an embodiment, the plurality of cells may have any suitable spatial arrangement, including a lateral arrangement of cells, a vertical arrangement of cells or a combination of laterally arranged cells and vertical arranged cells. In one embodiment, modular system 400 comprises a plurality of cells spatially arranged in a single row of contiguous cells, wherein each cell is isolated from an adjacent cell. In another embodiment, the plurality of cells may be spatially arranged in a single row of contiguous cells, wherein each cell may be isolated from an adjacent cell by at least one common side wall. In another embodiment, the plurality of cells may be arranged vertically in space in single column of contiguous cells, wherein each cell is isolated from an adjacent cell by at least one common wall. In yet another embodiment, the plurality of cells may be spatially arranged in a plurality of rows of contiguous cells. In one embodiment, modular system 400 includes a first cell 217, a second cell 218, and a third cell 232, first cell 217 being adjacent second cell 218 and contiguous therewith, and third cell 232 being adjacent to second cell 218 and being contiguous therewith, wherein first cell 217, second cell 218 and third cell 232 are spatially arranged in a single row of cells. Modular system 400 may contain one or more assembly lines that move containers 216 sequentially through modular system 400. As illustrated in FIGS. 2-4, an exemplary modular system 400 for processing and/or storing and/or disposing of a hazardous waste material includes parallel assembly lines of a plurality of cells for manipulating container 216. In some embodiments, as described above, the plurality of cells for manipulating container 216 includes at least first cell 217, second cell 218, third cell 232 and fourth cell 230. In other embodiments, any number of cells may be provided. In some embodiments, the cells may be held at different pressures relative to adjacent cells to control contamination from spreading between cells. For example, each subsequent cell may have a higher pressure than the previous cell such that any air flow between cells flows toward the beginning of the process, in some embodiments, first cell 217 is held at a first pressure P1 and second cell 218 is held at a second pressure P2, in one embodiment, first pressure P1 is less than second pressure P2. In such embodiments, first cell 217 does not exchange air with second cell 218 at least during the time when container 216 is being manipulated in first cell 217. In another such embodiment, an air interlock 241 (see FIG. 12), as described in further detail below, couples first cell 217 to second cell 218 and is configured to allow transfer of container 216 from first cell 217 to second cell 218 while maintaining at least one seal between first cell 217 and second cell 218. In another embodiment, first cell 217 is held at first pressure P1, second cell is held at second pressure P2 and third cell 232 is held at a third pressure P3, where third pressure P3 is greater than second pressure P2 which is greater than first pressure P1. In such embodiments, third cell 232 is isolated from first cell 217 and second cell 218, wherein second cell 218 and third cell 232 are configured to allow transfer of container 216 from second cell 218 to third cell 232. In yet another embodiment, first cell 217 is held at first pressure P1, second cell 218 is held at second pressure P2, third cell 232 is held at third pressure P3 and fourth cell 230 is held at a fourth pressure P4, wherein fourth pressure P4 is greater than third pressure P3, third pressure P3 is greater than second pressure P2 which is greater than first pressure P1. In such embodiments, fourth cell 230 is isolated from first cell 217, second cell 218 and third cell 232, wherein third cell 232 and fourth cell 230 are configured to allow transfer of container 216 from third cell 232 to the fourth cell 230. In one embodiment, each pressure P1, P2, P3 and/or P4 is negative relative to normal atmospheric pressure. In some embodiments, the pressure difference between first cell 217 and second cell 218 is about 10 KPa to about 20 KPa. In some embodiments, the pressure difference between second cell 218 and third cell 232 is about 10 KPa to about 20 KPa. In some embodiments, the pressure difference between third cell 232 and fourth cell 230 is about 10 KPa to about 20 KPa. I. First Cell Exemplary embodiments of first cell 217 are illustrated in FIGS. 3, 4 and 7, in one embodiment, first cell 217 is a filling cell which allows for filling a container 216 with hazardous waste with minimal contamination of the exterior of container 216. In one embodiment, empty containers 216 are first introduced into the modular system 400. In one embodiment, empty containers 216 are placed in first cell 217 and first cell 217 is sealed before transferring any hazardous waste material within first cell 217. In one embodiment, once first cell 217 is sealed and contains one or more empty containers 216, first cell 217 is brought to pressure P1. Container and Method of Filling a Container Containers of various designs may be used in accordance with the various embodiments of the present disclosure. A schematic container 216, which may be a HIP can, is shown throughout in FIGS. 2, 3, 4, 7, 13, 15, 16 and 17. Container 216 may have any suitable configuration known in the art for HIP processing. In some embodiments, container 216 is provided with a single port. In other embodiments, container 216 is provided with a plurality of ports. Some particular configurations for containers 216 that may be used in accordance with the various embodiments of the present invention are shown in FIGS. 5A, 5B, 6A and 6B, which illustrate exemplary containers configured to scalingly contain hazardous waste material in accordance with the present disclosure. FIGS. 5A and 6A show one embodiment of a container, generally designated 500, for containment and storage of nuclear waste materials or other desired contents in accordance with an exemplary embodiment of the present invention. Container 500, in some embodiments, is particularly useful in HIP processing of waste materials. It should however be understood that container 500 can be used to contain and store other materials including nonnuclear and other waste materials. According to some embodiments, container 500 generally includes body 510, lid 520, filling port 540, and evacuation port 560. In some embodiments, container 500 also includes filling plug 550 configured to engage with filling port 540. In further embodiments, container 500 also includes evacuation plug 570 configured to engage with evacuation port 560. In yet further embodiments, container 500 includes lifting member 530. Body 510 has a central longitudinal axis 511 and defines interior volume 516 for containing nuclear waste materials or other materials according to certain embodiments of the invention, in some embodiments, a vacuum can be applied to interior volume 516. In some embodiments, body 510 has a cylindrical or a generally cylindrical configuration having closed bottom end 515. In some embodiments, body 510 is substantially radially symmetric about central longitudinal axis 511. In some embodiments, body 510 may be configured to have the shape of any of the containers described in U.S. Pat. No. 5,248,453, which is incorporated herein by reference in its entirety. In some embodiments, body 510 is configured similarly to body 110 of container 100 shown in FIG. 1. Referring to FIG. 5A, in some embodiments body 510 has one or more sections 512 having a first diameter alternating along central longitudinal axis 511 with one or more sections 514 having a smaller second diameter. Body 510 may have any suitable size. In some embodiments, body 510 has a diameter in a range of about 60 mm to about 600 mm. In some embodiments, body 510 has a height in a range of about 120 mm to about 1200 mm. In some embodiments, body 510 has a wall thickness of about 1 mm to about 5 mm. Body 510 may be constructed from any suitable material known in the art useful in hot isostatic pressing of nuclear waste materials. In some embodiments, body 510 is constructed of material capable of maintaining a vacuum within body 500. In some embodiments, body 510 is constructed from a material that is resistant to corrosion. In some embodiments, body 510 is made from a metal or metal alloy, for example, stainless steel, copper, aluminum, nickel, titanium, and alloys thereof. In some embodiments, container 500 includes a lid 520 opposite closed bottom end 515. Lid 520, in some embodiments, is integrally formed with body 510. In other embodiments, lid 520 is formed separately from body 510 and secured thereto, for example, via welding, soldering, brazing, fusing or other known techniques in the art to form a hermetic seal circumferentially around lid 520. In some embodiments, lid 520 is permanently secured to body 510. Referring to FIG. 6A, lid 520 includes interior surface 524 facing interior volume 516 and exterior surface 526 opposite interior surface 524. In some embodiments, central longitudinal axis 511 is substantially perpendicular to interior surface 524 and exterior surface 526. In some embodiments, central longitudinal axis 511 extends through a center point of interior surface 524 and exterior surface 526. In some embodiments, container 500 further includes a flange 522 surrounding exterior surface 526. In some embodiments, container 500 further includes a filling port 540 having an outer surface 547, an inner surface 548 defining a passageway in communication with interior volume 516, and configured to couple with a filling nozzle. In some embodiments, the nuclear waste material to be contained by container 500 is transferred into interior volume 516 through filling port 540 via the filling nozzle. In some embodiments, filling port 540 is configured to at least partially receive the filling nozzle therein. In some embodiments, inner surface 548 of filling port 540 is configured to form a tight seal with a filling nozzle so as to prevent nuclear waste material from exiting interior volume 516 between inner surface 548 of filling port 540 and the filling nozzle during filling of container 500. Filling port 540 may extend from lid 520 as shown in the exemplary embodiment of FIGS. 5A and 6A. In some embodiments, filling port 540 may be integrally formed with lid 520. In other embodiments, filling port 540 is formed separately from lid 520 and secured thereto, for example, by welding. In some embodiments, filling port 540 is constructed from metal or metal alloy, and may be made from the same material as body 510 and/or lid 520. Referring particularly to FIG. 6A, filling port 540 has a generally tubular configuration with inner surface 548 extending from first end 542 towards second end 543. According to some embodiments, filling port 540 extends from lid 520 along an axis 541 substantially parallel to central longitudinal axis 511. In some embodiments, inner surface 548 is radially disposed about axis 541, in some embodiments, first end 542 of filling port 540 defines an opening in lid 520 and has an internal diameter Df1. In some embodiments, second end 543 of filling port 540 has an internal diameter Df2 which may be different than diameter Df1. In some embodiments, Df2 is larger than Df1. In one embodiment, for example, Df1 is about 33 mm and Df2 is about 38 mm. In some embodiments, a stepped portion 549 is provided on the exterior of filling port 540. In some embodiments, stepped portion can be used for positioning an orbital welder e.g., orbital welder 242 described herein below). Container 500, in some embodiments, further includes a filling plug 550 configured to couple with filling port 540, in some embodiments, filling plug 550 is configured and dimensioned to be at least partially received in filling port 540 as generally shown in FIG. 6A. In some embodiments, filling plug 550 is radially disposed about axis 541 when coupled with filling port 540. In some embodiments, filling plug 550 is configured to close and seal filling port 540 to prevent, material from exiting interior volume 516 via filling port 540. Filling plug 550, in some embodiments, is configured to abut inner surface 548 when coupled to filling port 540. In some embodiments, filling plug 550 includes a portion having a diameter substantially equal to an internal diameter of filling port 540. In some embodiments, filling plug 550 includes a first portion 552 having a diameter substantially equal to Df1. In some embodiments, filling plug 550 alternatively or additionally includes a second portion 553 having a diameter substantially equal to Df2. In some embodiments, second portion 553 is configured to abut surface 544 when filling plug 550 is coupled with filling port 540. In some embodiments, filling plug 550 further abuts end surface 545 when filling plug 550 is coupled with filling port 540. In some embodiments, filling plug 550 when coupled with filling port 540 creates a seam 546. In some embodiments, seam 546 is formed at an interface between filling plug 550 and end surface 545 of second end 543 of filling port 540. In some embodiments, seam 546 is located between external surface 551 of filling plug 550 and external surface 547 of filling port 540. In some embodiments, external surface 551 of filling plug 550 is substantially flush with external surface 547 of filling port 540 proximate seam 546. Seam 546 extends circumferentially around a portion of filling plug 550 according to some embodiments. Filling port 540 and filling plug 550 may be secured together according to some embodiments by any suitable method known in the art. In some embodiments, filling plug 550 is threadably coupled with filling port 540. According to some of these embodiments, at least a portion of inner surface 548 is provided with internal threads that are configured to engage with external threads provided on at least a portion of filling plug 550 such that, for example, filling plug 550 may be screwed into filling port 540. In some embodiments, one or more of portions 552 and 553 may be provided with external threads that engage with internal threads provided on inner surface 548 of filling port 540. In other embodiments, filling port 540 and filling plug may be coupled via an interference or friction fit. In some embodiments, container 500 includes a gasket (not shown) positioned within filling port 540 to aid in sealing filling port 540 with filling plug 550. In some embodiments, a gasket is positioned between filling plug 550 and surface 544 In some embodiments, filling port 540 and filling plug 550 may be permanently secured together after filling of container 500 with the nuclear waste material or other desired contents, in some embodiments, filling port 540 and filling plug 550 may be mechanically secured together. In some embodiments, filling port 540 may be fused with filling plug 550. In some embodiments, filling port 540 and filling plug 550 may be soldered or brazed together. In some embodiments, filling port 540 and filling plug 550 may be welded together along seam 546, for example, by orbital welding. In other embodiments, an adhesive or cement may be introduced into seam 546 to seal filling port 540 and filling plug 550 together. In some embodiments, container 500 includes an evacuation port 560 having an outer surface 567 and an inner surface 568 defining a passageway in communication with interior volume 516. In some embodiments, evacuation port 560 is configured to allow venting of air or other gas from interior volume 516. In some embodiments, evacuation port 560 is configured to couple with an evacuation nozzle, as described further below, for evacuating air or other gas from interior volume 516 in some embodiments, the evacuation nozzle is connected with a ventilation or vacuum system capable of drawing air or other gas from interior volume 516 through evacuation port 560. Evacuation port 560 may extend from lid 520 as shown in the exemplary embodiment of FIGS. 5A and 6A. In some embodiments, evacuation port 560 may be integrally formed with lid 520. In other embodiments, evacuation port 560 is formed separately from lid 520 and secured thereto, for example, by welding, soldering, brazing, or the like. In some embodiments, evacuation port 560 is constructed from metal or metal alloy, and may be made from the same material as body 510 and/or lid 520. Referring particularly to FIG. 6A, evacuation port 560 has a generally tubular configuration with inner surface 568 extending from first end 562 towards second end 563. According to some embodiments, evacuation port 560 extends from lid 520 along an axis 561 substantially parallel to central longitudinal axis 511. In some embodiments, axis 561 is coplanar with central longitudinal axis 511 and axis 541 of filling port 540. In some embodiments, inner surface 568 is radially disposed about axis 561. In some embodiments, first end 562 of evacuation port 560 defines an opening in lid 520 and has an internal diameter De1. In some embodiments, second end 563 of evacuation port 560 has an internal diameter De2 which may be different than diameter De1. In some embodiments, D is larger than De1. In some embodiments, evacuation port 560 may further include one or more intermediate sections positioned between first end 562 and second end 563 defining internal diameters different than De1 and De2. In the exemplary embodiment shown in FIG. 6A, evacuation port 562 includes intermediate sections 564 and 565 respectively have internal diameters De3 and De4 and configured such that De1<De3<De4<De2. In some embodiments, evacuation port 560 has the same external diameter as filling port 540. In some embodiments, a stepped portion 569 is provided on the exterior of evacuation port 560. In some embodiments, stepped portion 569 can be used for positioning an orbital welder (e.g. orbital welder 242 described therein below). In some embodiments, stepped portion 569 can be used for positioning the evacuation nozzle. According to some embodiments of the invention, evacuation port 560 is provided with a filter 590. In some embodiments, filter 590 is sized to span across the passageway defined by evacuation port 560. In some embodiments, filter 590 is positioned within evacuation port 560 at or proximate to first end 562 and has a diameter substantially equal to De1. In some embodiments, the filter 590 is sealingly engaged to inner surface 568 of evacuation port 560. In some embodiments, the filter 590 is secured to inner surface 568 of evacuation port 560, for example, via welding, soldering, brazing, or the like, in one embodiment, filter 590 is a high efficiency particulate air (HEPA) filter. In some embodiments, filter 590 is a single layer of material. In some embodiments, filter 590 is multi-layer material. In some embodiments, filter 590 is made from sintered material. In some embodiments, filter 590 is made from metal or metal alloy, for example, stainless steel, copper, aluminum, iron, titanium, tantalum, nickel, and alloys thereof, in some embodiments, filter 590 is made from a ceramic, for example, aluminum oxide (Al2O3) and zirconium oxide (ZrO2). In some embodiments, filter 590 includes carbon or a carbon compound, for example, graphite. In some embodiments, the material of filter 590 is chosen so that upon heating the filter densities into a solid and non-porous material. In some embodiments, the material of filter 590 is chosen wherein at a first temperature filter 590 is porous to air and/or gas but prevents passage of particles and at a second temperature filter 590 densities into a non-porous material, wherein the second temperature is greater than the first temperature. In some embodiments, filter 590 is configured to prevent passage of particles having a predetermined dimension through evacuation port 560 while allowing passage of air or other gas. In some embodiments, filter 590 is configured to prevent passage of particles having a dimension greater than 100 μm through evacuation port 560. In some embodiments, filter 590 is configured to prevent passage of particles having a dimension greater than 75 μm through evacuation port 560. In some embodiments, filter 590 is configured to prevent passage of particles having a dimension greater than 50 μm through evacuation port 560. In some embodiments, filter 590 is configured to prevent passage of particles having a dimension greater than 25 μm through evacuation port 560. In some embodiments, filter 590 is configured to prevent passage of particles having a dimension greater than 20 μm through evacuation port 560. In some embodiments, filter 590 is configured to prevent passage of particles having a dimension greater than 15 μm through evacuation port 560. In some embodiments, filter 590 is configured to prevent passage of particles having a dimension greater than 12 μm through evacuation port 560. In some embodiments, filter 590 is configured to prevent passage of particles having a dimension greater than 10 μm through evacuation port 560. In some embodiments, filter 590 is configured to prevent passage of particles having a dimension greater than 8 μm through evacuation port 560, in some embodiments, filter 590 is configured to prevent passage of particles having a dimension greater than 5 μm through evacuation port 560. In some embodiments, filter 590 is configured to prevent passage of particles having a dimension greater than 1 μm through evacuation port 560. In some embodiments, filter 590 is configured to prevent passage of particles having a dimension greater than 0.5 μm through evacuation port 560. In some embodiments, filter 590 is configured to prevent passage of particles having a dimension greater than 0.3 μm through evacuation port 560. Container 500, in some embodiments, further includes an evacuation plug 570 configured to couple with evacuation port 560. In some embodiments, evacuation plug 570 is configured and dimensioned to be at least partially received in evacuation port 560 as generally shown in FIG. 6A. In some embodiments, evacuation plug 570 is radially disposed about axis 561 when coupled with filling port 560. In some embodiments, evacuation plug 570 is configured to allow air and/or other gas to pass through evacuation port 560 in a filling configuration and to close filling evacuation port 560 in a closed configuration to prevent air and/or other gas from passing through evacuation port 560. In some embodiments, evacuation plug 570 includes a portion having a diameter substantially equal to or slightly less than an internal diameter of evacuation port 560. In some embodiments, evacuation plug 570 includes a first portion 572 having a diameter substantially equal to or slightly less than De1. In some embodiments, evacuation plug 570 alternatively or additionally includes a second portion 573 having a diameter substantially equal to De2. In some embodiments, evacuation plug 570 alternatively or additionally includes intermediate portions 574 and 575 having respective diameters substantially equal to or slightly less than De3 and De4. In some embodiments, evacuation plug 570 when coupled with evacuation port 550 creates a seam 566. In some embodiments, seam 566 is formed at an interface between evacuation plug 570 and second end 563 of evacuation port 560. In some embodiments, seam 566 is located between external surface 571 of evacuation plug 570 and external surface 567 of evacuation port 560. In some embodiments, external surface 571 of evacuation plug 570 is substantially flush with external surface 567 of evacuation port 560 proximate seam 566. Seam 566 extends circumferentially around a portion of evacuation plug 570 according to some embodiments. According to some embodiments of the invention, evacuation plug 570 is configured to be at least partially received within evacuation port 560 in a filling configuration such that air and/or other gas is allowed to exit from interior volume 516 of container 500 through filter 590 and through evacuation port 560 between inner surface 568 of evacuation port 560 and evacuation plug 570. In some embodiments, evacuation plug 570 and evacuation port 560 are coupled in the filling configuration such that a gap 582 of sufficient dimension to allow for air and/or other gas to pass there through is maintained between evacuation plug 570 and evacuation port 560 to provide a pathway for air and/or other gas to evacuated from interior volume 516. In some embodiments, gap 582 extends circumferentially around at least a portion of evacuation plug 570. In some embodiments, air and/or other gas is allowed to pass through gap 582 and through seam 566 in the filling configuration. In some embodiments, evacuation plug 570 and evacuation port 560 are coupled in the filling configuration such that a space 581 is maintained between evacuation plug 570 and filter 590. When present, space 581 should be of sufficient distance along the axial direction (e.g., along axis 561) to allow for air and/or other gas to pass through filter 590. In some embodiments, container 500 is further configured to transition from the filling configuration to a closed configuration wherein the evacuation plug 570 is coupled with evacuation port 560 such that air and/or other gas is not allowed to pass through evacuation port 560. In some embodiments, evacuation port 560 is hermetically sealed by the evacuation plug 570 in the dosed configuration. In some embodiments, the closed configuration allows a vacuum to be maintained in interior volume 516. In some embodiments, in the closed configuration, evacuation plug 570 is at least partially received within evacuation port 560 to close and seal the passageway defined by evacuation port 560 to prevent material from passing therethrough. In some embodiments, a gasket 580 is provided between evacuation port 560 and evacuation plug 570. In some embodiments, gasket 580 aids in sealing the evacuation port 560 with the evacuation plug 570 in the closed configuration. Gasket 580, in some embodiments, surrounds at least a portion of evacuation plug 570. In the embodiment of FIG. 6A, gasket 580 is shown surrounding portion 575 of evacuation plug 570 and is positioned between and configured to abut second portion 573 of evacuation plug 570 and intermediate section 565 of evacuation port 560. In some embodiments, gasket 580 can be made from a metal or metal alloy, for example stainless steel, copper, aluminum, iron, titanium, tantalum, nickel, and alloys thereof. In some embodiments, gasket 580 is made from a ceramic, for example, aluminum oxide (Al2O3) and zirconium oxide (ZrO2). In some embodiments, gasket 580 includes carbon or a carbon compound, for example, graphite. In some embodiments, evacuation plug 570 is threadably coupled with evacuation port 560. According to some of these embodiments, at least a portion of inner surface 568 is provided with internal threads that are configured to engage with external threads provided on at least a portion of evacuation plug 570 such that, for example, evacuation plug 570 may be screwed into evacuation port 560. In some embodiments, one or more of portions 572, 573, 574, and 575 may be provided with external threads that engage with internal threads provided on inner surface 568 of evacuation port 560. In some embodiments, the filling configuration includes partially engaging the external threads of evacuation plug 570 with the internal threads of evacuation port 560 (e.g., partially screwing evacuation plug 570 into evacuation, port 560) and the closed configuration includes fully engaging the external threads of evacuation plug 570 with the internal threads of evacuation port 560 (e.g., fully screwing evacuation plug 570 into evacuation port 560). In some embodiments, evacuation port 560 and evacuation plug 570 may be permanently secured together. In some embodiments, evacuation port 560 and evacuation plug 570 may be mechanically secured together. In some embodiments, evacuation port 560 may be fused with evacuation plug 570. In some embodiments, evacuation port 560 and evacuation plug 570 may be soldered or brazed together. In some embodiments, evacuation port 560 and evacuation plug 570 may be welded together along seam 566, for example, by orbital welding. In such embodiments, the weld is placed between the evacuation port 560 and evacuation plug 570 away from the gasket 580 so not to disrupt the hermetic seal maintaining the atmosphere in the container 500. In other embodiments, an adhesive or cement may be introduced into seam 566 to seal evacuation port 560 and evacuation plug 550 together. Referring to FIGS. 5A and 6A, container 500, in some embodiments, includes lifting member 530 which is configured to engage with a carrier for lifting and/or transporting container 500. Lifting member 530, according to some embodiments, is securely attached to and extends from exterior surface 526 of lid 520. In some embodiments, lifting member 530 is positioned centrally on exterior surface 526 of lid 520. In some embodiments, lifting member 530 is integrally formed with lid 520. In other embodiments, lifting member is formed separately from lid 520 and secured thereto, for example, by welding, soldering, brazing, or the like. In some embodiments, lifting member 530 is constructed from metal or metal alloy, and may be made from the same material as body 510 and/or lid 520. In the exemplary embodiment shown, lifting member 530 includes a generally cylindrical projection 532 extending from lid 520 substantially co-axial with central longitudinal axis 511. In some embodiments, lifting member 530 is radially symmetric about central longitudinal axis 511. In some embodiments, lifting member 530 is positioned on lid 520 between filling port 540 and evacuation port 560. In some embodiments, lifting member 530 includes a groove 533 that extends at least partially around the circumference of projection 532. In further embodiments, lifting member 530 includes a flange 534 that partially defines groove 533. FIGS. 5B and 6B show another embodiment of a container, generally designated 600, for containment and storage of nuclear waste materials or other desired contents in accordance with an exemplary embodiment of the present invention. Container 600, in some embodiments, is particularly useful in hot isostatic pressing of waste materials, in some embodiments, body 610 is constructed of material capable of maintaining a vacuum within body 600. According to some embodiments, container 600 generally includes body 610, lid 620, and filling port 640. In some embodiments, container 600 also includes filling plug 650 configured to engage with filling port 640. Body 610 has a central longitudinal axis 611 and defines interior volume 616 for containing nuclear waste materials or other materials according to certain embodiments of the invention. In some embodiments, a vacuum can be applied to interior volume 616. In some embodiments, body 610 has a cylindrical or a generally cylindrical configuration having closed bottom end 615, in some embodiments, body 610 is substantially radially symmetric about central longitudinal axis 611. In some embodiments, body 610 may be configured to have the shape of any of the containers described in U.S. Pat. No. 5,248,453, which is incorporated herein by reference in its entirety. In some embodiments, body 610 is configured similarly to body 110 of container 100 shown in FIG. 1. Referring to FIG. 5B, in some embodiments body 610 has one or more sections 612 having a first diameter alternating along central longitudinal axis 611 with one or more sections 614 having a smaller second diameter. Body 610 may have the same configuration and dimensions described herein for body 510. Body 610 may be constructed from any suitable material known in the art useful in hot isostatic pressing of nuclear waste materials. In some embodiments, body 610 is constructed from a material that is resistant to corrosion. In some embodiments, body 610 is made from a metal or metal alloy, for example, stainless steel, copper, aluminum, nickel, titanium, and alloys thereof. In some embodiments, container 600 includes a lid 620 opposite closed bottom end 615. Lid 620, in some embodiments, is integrally formed with body 610. In other embodiments, lid 620 is formed separately from body 610 and secured thereto, for example, via welding, soldering, brazing, fusing or other known techniques in the art to form a hermetic seal circumferentially around lid 620. In some embodiments, lid 620 is permanently secured to body 610. Referring to FIG. 6B, lid 620 includes interior surface 624 facing interior volume 616 and exterior surface 626 opposite interior surface 624. In some embodiments, central longitudinal axis 611 is substantially perpendicular to interior surface 624 and exterior surface 626. In some embodiments, central longitudinal axis 611 extends through a center point of interior surface 624 and exterior surface 626. In some embodiments, container 600 further includes a flange 622 surrounding exterior surface 626. In some embodiments, container 600 further includes a filling port 640 having an outer surface, a stepwise inner surface 647 and a lower inner surface 648 defining a passageway in communication with interior volume 616, and configured to couple with a filling nozzle. In some embodiments, the nuclear waste material to be contained by container 600 is transferred into interior volume 616 through filling port 640 via the filling nozzle, in some embodiments, filling port 640 is configured to at least partially receive the filling nozzle therein. In some embodiments, stepwise inner surface 647 and/or lower inner surface 648 of filling port 640 is configured to form a tight seal with a filling nozzle so as to prevent nuclear waste material from exiting interior volume 616 between stepwise inner surface 647 and lower inner surface 648 of filling port 640 and the filling nozzle during filling of container 600. Filling port 640 may extend from lid 620 as shown in the exemplary embodiment of FIGS. 5B and 6B. In some embodiments, filling port 640 may be integrally formed with lid 620. In other embodiments, filling port 640 is formed separately from lid 620 and secured thereto, for example, by welding. In some embodiments, filling port 640 is constructed from metal or metal alloy, and may be made from the same material as body 610 and/or lid 620. Referring particularly to FIG. 6B, filling port 640 has a generally step wise tubular configuration with stepwise inner surface 647 and lower inner surface 648 extending from first end 642 towards second end 643. According to some embodiments, filling port 640 extends from lid 620 along an axis 641 substantially coaxial to central longitudinal axis 611. In some embodiments, stepwise inner surface 647 is radially disposed about axis 641, in some embodiments, lower inner surface 648 is radially disposed about axis 641. In some embodiments, first end 642 of filling port 640 defines an opening in lid 620 and has an internal diameter Dg1. In some embodiments, second end 643 of filling port 640 has an internal diameter Dg2 which may be different than diameter Dg1. In some embodiments, Dg2 is larger than Dg1. In some embodiments, filling port 640 is provided with a flange 634 at least partially defining a groove 633. In some embodiments, flange 634 and groove 633 extend circumferentially around filling port 640. In some embodiments, flange 634 and groove 633 are radially symmetric about axis 641. In some embodiments, flange 634 and/or groove 633 are configured to engage with a carrier for lifting or transporting container 600. Container 600, in some embodiments, further includes a filling plug 650 configured to couple with filling port 640. In some embodiments, filling plug 650 is configured and dimensioned to be at least partially received in filling port 640 as generally shown in FIG. 6B. In some embodiments, filling plug 650 is radially disposed about axis 641 when coupled with filling port 640. In some embodiments, filling plug 650 is configured to close and seal filling port 640 to prevent material from exiting interior volume 616 via filling port 640. In some embodiments, filling plug 650 is configured for hermetically scaling filling port 640. Filling plug 650, in some embodiments, is configured to abut stepwise inner surface 647 when coupled to filling port 640. In some embodiments, filling plug 650 includes a first portion 673 having a diameter substantially equal to Dg2. In some embodiments, filling plug 650 alternatively or additionally includes a second portion 675 having a diameter substantially equal to Dg3. In some embodiments, filling plug 650 alternatively or additionally includes a third portion 674 having a diameter substantially equal to Dg4. In some embodiments, first portion 673 is configured to abut surface 649 when filling plug 650 is coupled with filling port 640. In some embodiments, filling plug 650 when coupled with filling port 640 creates a seam 646. In some embodiments, seam 646 is formed at an interface between filling plug 650 and end surface 645 of second end 643 of filling port 640. In some embodiments, seam 646 is located between an external surface of filling plug 650 and an external surface of filling port 640. In some embodiments, the external surface of filling plug 650 is substantially flush with the external surface of filling port 640 proximate seam 646. Seam 646 extends circumferentially around a portion of filling plug 650 according to some embodiments. Filling port 640 and filling plug 650 may be secured together according to some embodiments by any suitable method known in the art. In some embodiments, filling plug 650 is threadably coupled with filling port 640. According to some of these embodiments, at least a portion of inner surface 648 is provided with internal threads that are configured to engage with external threads provided on at least a portion of filling plug 650 such that, for example, filling plug 650 may be screwed into filling port 640. In some embodiments, one or more of portions 652 and 653 may be provided with external threads that engage with internal threads provided on inner surface 648 of filling port 640. In other embodiments, filling port 640 and filling plug may be coupled via an interference or friction fit. In some embodiments, a gasket 680 is provided between filling port 640 and filling plug 650. In some embodiments, gasket 680 aids in sealing the filling port 640 with the filling plug 650 in a closed configuration. Gasket 680, in some embodiments, surrounds at least a portion of filling plug 650. In the embodiment of FIG. 6B, gasket 680 is shown surrounding portion 675 of filling plug 650 and is positioned between and configured to abut portion 673 of filling plug 650 and filling port 640. In some embodiments, gasket 680 can be made from a metal or metal alloy, for example stainless steel, copper, aluminum, iron, titanium, tantalum, nickel, and alloys thereof. In some embodiments, gasket 680 is made from a ceramic, for example, aluminum oxide (Al2O3) and zirconium oxide (ZrO2). In some embodiments, gasket 680 includes carbon or a carbon compound, for example, graphite. In some embodiments, filling port 640 and filling plug 650 may be permanently secured together after filling of container 600 with the nuclear waste material or other desired contents. In some embodiments, filling port 640 and filling plug 650 may be mechanically secured together. In some embodiments, filling port 640 may be fused with filling plug 650. In some embodiments, filling port 640 and filling plug 650 may be soldered or brazed together. In some embodiments, filling port 640 and filling plug 650 are configured to provide a hermetic seal. In some embodiments, filling port 640 and filling plug 650 may be welded together along seam 646, for example, by orbital welding. In such embodiments, the weld is placed between the filling plug 650 and filling port 640 away from the gasket 680 so as not to disrupt the hermetic seal maintaining the atmosphere in the container 600. In other embodiments, an adhesive or cement may be introduced into seam 646 to seal filling port 640 and filling plug 650 together. According to some embodiments of the invention, filling plug 650 is provided with a filter 690. In some embodiments, filter 690 is sized to span the circular end section 670 of filling port 650. In some embodiments, the filter 690 is sealingly engaged to circular end section 670 of filling plug 650. In some embodiments, the filter 690 is secured to circular end section 670 of filling plug 650, for example, via welding, soldering, brazing, or the like. In some embodiments, filter 690 is secured to filling plug 650 with a mechanical fastener 695, such as a screw, nail, bolt, staple, or the like, in one embodiment, filter 690 is a high efficiency particulate air (HEPA) filter. In some embodiments, filter 690 is a single layer of material. In some embodiments, filter 690 is multi-layer material. In some embodiments, filter 690 is made from sintered material. In some embodiments, filter 690 is made from metal or metal alloy, for example, stainless steel, copper, aluminum, iron, titanium, tantalum, nickel, and alloys thereof in some embodiments, filter 690 is made from a ceramic, for example, aluminum oxide (Al2O3), aluminosilicates (eg. Al2SiO5) and zirconium oxide (ZrO2). In some embodiments, filter 690 includes carbon or a carbon compound, for example, graphite. In some embodiments, the material of filter 690 is chosen so that upon heating the filter densifies into a solid and non-porous material. In some embodiments, the material of filter 690 is chosen wherein at a first temperature filter 690 is porous to air and/or gas but prevents passage of particles and at a second temperature filter 690 densifies into a nonporous material, wherein the second temperature is greater than the first temperature. In some embodiments, filter 690 is configured to prevent passage of particles having a predetermined dimension through filling port 640 while allowing passage of air or other gas when filling plug 560 is coupled with filling port 640. In some embodiments, filter 690 is configured to prevent passage of particles having a dimension greater than 100 μm through filling port 640. In some embodiments, filter 690 is configured to prevent passage of particles having a dimension greater than 75 μm through filling port 640. In some embodiments, filter 690 is configured to prevent passage of particles having a dimension greater than 50 μm through filling port 640. In some embodiments, filter 690 is configured to prevent passage of particles having a dimension greater than 25 μm through filling port 640. In some embodiments, filter 690 is configured to prevent passage of particles having a dimension greater than 20 μm through filling port 640. In some embodiments, filter 690 is configured to prevent passage of particles having a dimension greater than 15 μm through filling port 640. In some embodiments, filter 690 is configured to prevent passage of particles having a dimension greater than 12 μm through filling port 640. In some embodiments, filter 690 is configured to prevent passage of particles having a dimension greater than 10 μm through filling port 640. In some embodiments, filter 690 is configured to prevent passage of particles having a dimension greater than 8 μm through filling port 640. In some embodiments, filter 690 is configured to prevent passage of particles having a dimension greater than 5 μm though filling port 640. In some embodiments, filter 690 is configured to prevent passage of particles having a dimension greater than 1 μm through filling port 640. In some embodiments, filter 690 is configured to prevent passage of particles having a dimension greater than 0.5 μm through filling port 640. In some embodiments, filter 690 is configured to prevent passage of particles having a dimension greater than 0.3 μm through filling port 640. According to some embodiments of the invention, filling plug 650 is configured to be at least partially received within filling port 640 in a filling configuration such that air and/or other gas is allowed to exit from interior volume 616 of container 600 through filter 690 and between stepwise inner surface 647 of filling port 640 and filling plug 650. In some embodiments, filling plug 650 and filling port 640 are coupled in the filling configuration such that a gap (not shown) of sufficient dimension to provide a pathway for air and/or other gas to evacuated from interior volume 616. In some embodiments, the gap extends circumferentially around at least a portion of filling plug 650. In some embodiments, air and/or other gas is allowed to pass through the gap and through scam 646 in the filling configuration. In operation, the interior volume of a container 216 is filled with material by coupling a filling port 540 to a filling nozzle 260 wherein container 216 is place under a negative pressure prior to filling or container 216 is simultaneously evacuated during the filling process according to some embodiments. In some embodiments, the filling port 540 is configured to tightly fit around the filling nozzle 260 to prevent material from exiting container 216 between the filling port 540 and the filling nozzle 260. In some embodiments, the filling of container 216 continues until the desired amount of material has been added to container 216. In some embodiments, a predetermined volume of material is added to container 216. In some embodiments, a predetermined weight of material is added to container 216. With reference to FIG. 6A, material to be stored (e.g., nuclear waste or calcined material) is added to interior volume 516 of container 500 via a filling nozzle 260 coupled to filling port 540 according to some embodiments. In some embodiments, the filling port 540 is configured to tightly fit around filling nozzle 260 to prevent material from exiting container 500 between the filling port 540 and filling nozzle 260. In some embodiments, as container 516 is being filled, air and/or other gas contained in interior volume 516 is evacuated from container 500 via evacuation port 560 provided with filter 590. In some embodiments, filter 590 prevents all or at least most non-gaseous materials from exiting container 500 through evacuation port 560 while the air and/or other gas is being evacuated from interior volume 516. In some embodiments, filter 590 is configured to prevent particles having a diameter of at least 10 μm from exiting interior volume 516 through evacuation port 560 during filling of waste material and air/gas evacuation. Evacuation of the air and/or other gas, in some embodiments, can be facilitated by coupling evacuation port 560 with an evacuation nozzle 300. Evacuation nozzle 300 may be coupled with an evacuation line or system (e.g., a vacuum source). In some embodiments, the evacuation line is operated at vacuum levels of about 25 to about 500 millitorr. After filling container 500 with the desired amount of material, filling nozzle 260 is replaced with filling plug 550 to close and seal filling port 540. In some embodiments, filling port 540 is hermetically sealed with filling plug 550. In some embodiments, filling plug 550 is welded to filling port 540. In some embodiments, an orbital welder 242 is used to weld filling plug 550 to filling port 540. In some embodiments, evacuation port 560 may be provided with evacuation plug 570. As previously described, evacuation plug 570 may be threadably coupled with evacuation port 560 in a first open configuration to allow air and/or other gas to pass through filter 590 and between evacuation plug 570 and evacuation port 560 and in a second closed configuration to hermetically seal and close evacuation port 560, in some embodiments, after filling is complete, evacuation port 560 is closed by evacuation plug 570. In some embodiments, evacuation port 560 is closed while evacuation nozzle 300 is coupled to evacuation port 560. With reference to FIG. 6B, container 600 is evacuated by coupling filling port 640 with an evacuation line or system (e.g., a vacuum source). Material is then added to interior volume 616 of container 600 via a filling nozzle 260 coupled to filling port 640. In some embodiments, the filling port 640 is configured to tightly fit around filling nozzle 260 to prevent material from exiting container 600 between the filling port 640 and filling nozzle 260. In some embodiments, container 600 is evacuated to a pressure of about 750 millitorr to about 1000 millitorr prior to filling. After filling container 600 with the desired amount of material, filling nozzle 260 is replaced with filling plug 650 to close and seal filling port 640 according to some embodiments. In some embodiments, container 600 is returned to the atmospheric pressure (e.g. the pressure of first cell 217) after filling. FIGS. 8-11 illustrate an exemplary filling system 299 for transferring hazardous waste material into a container 216 in accordance with various embodiments of the present invention. Filling system 299, in accordance with some embodiments of the present invention, is designed to prevent contamination of equipment and container exterior and elimination of secondary waste. The design features include, but are not limited to: container structure to allow container filling under vacuum; weight verification system and/or volume verification system and filling nozzle structure. As illustrated, in FIGS. 8-10, in some embodiments, system 299 for transferring hazardous waste material into a sealable container 216 includes a filling nozzle 260, at least one hopper 214, a pneumatic cylinder 285, a seal 284, a vibrator 281, a lift mechanism 282, a damper 283, a first scale 277, a second scale 278 and a processor 280. The system of FIGS. 8-11 may be used with a container having a single port, such as container 600, or a container having two ports, such as container 500, as described above herein. FIG. 8 illustrates a filling nozzle 260 relative to an exemplary container 216 having a single port 291. FIG. 9 illustrates a filling nozzle 260 relative to an exemplary container 216 having two ports, a filling port 292 and an evacuation port 293, in some embodiments, filling port 292 and evacuation port 293 may have the configuration of filling port 540 and evacuation port 560 of container 500 illustrated in FIGS. 5A and 6A. In one embodiment, the evacuation port 293 includes a filter 350. In some embodiments, filter 350 prevents the escape of hazardous waste particles from the container. Exemplary filter materials are discussed above herein. In some embodiments, filter 350 has the configuration of filter 590 as described above herein. In some embodiments, the transfer of hazardous waste is performed to prevent overpressure of container 216. In some embodiments, container 216 is at least initially under negative pressure before transfer of hazardous waste begins. In other embodiments, container 216 is under negative pressure simultaneously with the transfer of hazardous waste. In yet other embodiments, container 216 is initially under negative pressure before the filling process begins and is intermittently placed under negative pressure with the transfer of hazardous waste. In another embodiment, filling port 292 of container 216 is configured to be sealed closed after decoupling valve body 261 from filling port 292. In some embodiments, container 216 is filled at about 25° C. to about 35° C. In other embodiments, container 216 is filled at a temperature up to 100° C. Referring to FIGS. 2 and 11, in one embodiment, additive from the additive feed hopper 210 is added to the feed blender 212. In one such embodiment, the amount of additive is metered using an additive feed screw (not shown). Feed blender 212 is actuated to mix the calcined material with the additive. In one embodiment, feed blender 212 is a mechanical paddle-type mixer with the motor drives external to the cell. Referring to FIG. 8, in one embodiment a rotary airlock or ball valve 298, located between the feed blender 212 and hopper 214, transfers the mixed calcined material to feed hopper 214. In another embodiment, a rotary air lock or ball valve 298 is positioned between feed hopper 214 and container 216 to control transfer of material therebetween Referring to FIG. 7, in some embodiments, a fixed volume of the mixed calcined material is transferred from feed hopper 214 to container 216 which is located in first cell 217. In one embodiment, container 216 has two ports, a fill and an evacuation port, as described herein. In another embodiment, container 216 has a single port as described herein. Fill port 540, 640, attached to the top of container 216, is mated to a fill nozzle, discussed below herein, that is designed to eliminate spilling any of the hazardous material on the exterior of container 216. In one embodiment, fill nozzle 260 and fill port 540, 640 are configured to prevent contamination with waste material of the seal between a filling plug 550 and the interior of fill port 540, 640. In one embodiment, the amount of hazardous material transferred to a container is carefully controlled to ensure that container 216 is substantially full without overfilling container 216, in some embodiments, a weight verification system connected to hopper 214 and container 216 ensures that the proper amount of material is transferred. In some embodiments, equal volumes between hopper and container in combination with weight verification system connected to hopper 214 and container 216 ensure that the proper amount of material is transferred. In some embodiments, the weight verification system includes a processor 280 and a plurality of weigh scales 277. In some embodiments, a first scale 277 is coupled to the hopper 214 and configured to determine an initial hopper weight; a second scale 278 is coupled to the container 216 and configured to determine a container fill weight; and a processor 280 is coupled to the first scale 277 and the second scale 278 and configured to compare the initial hopper weight to the container fill weight. In some embodiments, initial hopper weight is the weight between flange 294 and flange 295 including hopper 214. In some embodiments, initial hopper weight means the weight of hazardous material within the hopper prior to filling container 216. In some embodiments, container fill weight means the weight of hazardous material in container 216 during the filling process and/or at the end of the filling process. In one embodiment, hopper 214 includes a volume substantially equal to a volume of container 216. In some embodiments, one or more vibrators 281 are provided to one or more components of filling system 299 to help ensure that all of the material is transferred from hopper 214 to container 216. In some embodiments, one or more vibrators 281 are configured to apply a vibrating force to one or more components of system 299 in order to assist in transferring the material to container 216. In some embodiments, vibrators 281 are configured to provide at least a force in a vertical direction. In some embodiments, vibrators 281 are configured to provide at least a force in a lateral direction. In one embodiment, at least one vibrator 281 is coupled to hopper 214, for example, to shake material from hopper 214 to container 216. In one embodiment, at least one vibrator 281 is coupled to a bottom of container 216. In one such embodiment, vibrator 281 coupled to bottom of container 216 is configured to provide vibration to container 216 in at least a vertical direction. In one embodiment, at least one vibrator 281 is coupled to a sidewall of the container 216. In one such embodiment, vibrator 281 coupled to the sidewall of container 216 is configured to provide vibration to container 216 in at least a lateral direction. The one or more vibrators 281, in some embodiments, are coupled a processor configured to control activation and/or operation (e.g., frequency) of vibrators 281. In some embodiments, processor 280 is coupled to the one or more vibrators 281. In some embodiments, one or more vibrators 281 are activated if container 216 is determined to be under-filled, for example, where the material to be transferred has been held up inside the system. In one embodiment, one or more vibrators 281 are activated if the container fill weight is less than the initial hopper weight. Referring to FIGS. 8 and 10, in one embodiment, filling nozzle 260 includes a valve body 261, a valve head 265 and a valve stem 267. Valve body 261 includes a distal end 262 and an outer surface 263, valve body 261 including a valve seat 264 proximate distal end 262, outer surface 263 proximate distal end 262 configured to scalingly and removeably couple valve body 261 to a filling port 272 of a container 216. In certain, embodiments, valve body 261 includes a first branch section 270 configured to couple to hopper 214. In one embodiment, a second branch section 269 includes the distal end 262 of the filling nozzle 260 and has a proximal end 288. In one embodiment, the proximal end 288 is coupled to a drive mechanism 289 configured to move the valve stem 267. In one embodiment, valve head 265 includes a valve face 266 configured to form a seal with the valve seat 264 in a closed configuration. In one embodiment, valve head 265 is configured to allow valve body 261 and container 216 to be fluidly coupled with one another in an open configuration. In certain embodiments, valve head 265 extends distally from valve body 261 and into container 216 in the open configuration. Valve stem 267 extends co-axially with axis 276 from valve head 265 through at least a portion of valve body 261. In a further embodiment, valve stem 267 extends through proximal end 288 of second branch section 269, proximal end 288 including a seal 284 coupled to a portion of valve stem 267. In some embodiments, filling nozzle 260 is sealed with filling port 272 of container 216 to prevent spilling of the hazardous waste material from container 216. In one embodiment, filling nozzle 260 extends into filling port 272 to prevent waste material from interfering with the seal between a filling plug (e.g. filling plug 650) and filling port 272 after removing filling nozzle 260. In some embodiments, outer surface 263 of distal end 262 includes at least one seal 273 to form a seal with filling port 272. In another embodiment, at least one seal 273 includes at least one o-ring. In one embodiment, at least one seal 273 includes two o-ring seals. In some embodiments, outer surface 263 includes a second seal 275 to form a seal with filling port 272. In some embodiments, filling port 272 has the configuration of filling port 640 of container 600, and at least one of seals 273 and 275 engages with lower inner surface 648 to form a seal therewith. In some embodiments, at least one of seals 273 and 275 engages with lower inner surface 648 at a position between first end 642 and where filter 690 engages filling port 640 as shown in FIG. 6B. In some embodiments, at least one of seals 273 and 275 engages with stepwise inner surface 647 at a position between first end 642 and gasket 680. In one embodiment, filling nozzle 260 further includes a sensor 274 disposed in valve head 265. In one embodiment, sensor 274 is configured to determine a level of hazardous material in container 216. In one embodiment, sensor 274 extends distally from valve body 264. In another embodiment, sensor 274 is coupled to a wire 268 that extends through valve stem 267. In one embodiment, sensor 274 is coupled to a wire 268 that extends through valve stem 267. Suitable sensors may include contact type sensors including displacement transducer or force transducer. In such embodiments, a displacement transducer senses filling powder height. In such embodiments, a force transducer includes a stain gauge on thin membrane that is deflected by the filling powder front. Suitable sensors may also include non contact type sensors including sonar, ultrasonic, and microwave. In one embodiment, a drive mechanism operates valve stem 267. In one embodiment, drive mechanism 289 includes a pneumatic cylinder 285. In some embodiments, a lift mechanism 282 is configured to lift container 216 toward filling nozzle 262. In one embodiment, lift mechanism 282 includes at least one damper 283. In one embodiment, the system for transferring hazardous waste material into the sealable container further comprises a vacuum nozzle 271 configured to be in fluid communication with container 216. In one embodiment, vacuum nozzle 271 extends through distal end 288 of valve body 261. In another embodiment, vacuum nozzle 271 includes a filter 279 proximate the distal end 262 of valve body 261. In certain embodiments, the system in accordance with the present invention further comprises a vacuum nozzle 271 scalingly and removeably couplable with the exhaust port 292, vacuum nozzle 271 being in sealed fluid communication with the valve body 261 in a filling configuration. In one embodiment, first cell 217 does not exchange air with subsequent cells while at least container 216 is being filled by the filling system 299. Referring to FIG. 7, in one embodiment, first cell 217 includes an off-gas sub-system 206 coupled to filling system 299 wherein off-gas sub-system 206 has a vacuum nozzle configured to couple to container 216. Referring to FIG. 12, in a further embodiment, first cell 217 is coupled to the second, subsequent cell 218 with one or more sealable doors 240, in one embodiment, the second, subsequent cell 218 is a bake-out and vacuum sealing cell. In one embodiment, first cell 217 is coupled to second cell 218 via an air interlock 241. In one embodiment, air interlock 241 is configured to allow container 216 to be transferred from first cell 217 to second cell 218. II. Second Cell Exemplary embodiments of second cell 218 and certain components thereof are illustrated in FIGS. 2, 3, 4, 12, 13, 14 and 16. In one embodiment, second cell 218 is a bake-out and vacuum sealing cell which allows for heating and evacuating container 216 followed by sealing of container 216. In one embodiment, first cell 217 is held at a first pressure P1 and second cell 218 is held at a second pressure P1, where the first pressure P1 is less than the second pressure P2. First cell 217 and second cell 218 are interconnected via the sealable door 240 according to some embodiments. In one embodiment, second cell 218 includes a baking and sealing station 243. In certain embodiments, second cell 218 further includes a welding station. Referring to FIG. 2, in one embodiment, second cell 218 includes a bake-out furnace 290, an off-gas system 206 having, a vacuum nozzle configured to couple to the container 216. In some embodiments, as shown in FIG. 16, second cell 218 further includes an orbital welder 242 configured to apply a weld to container 216. In one embodiment, referring to FIGS. 3 and 12, second cell 218 includes an interlock 241, interlock 241 coupling first cell 217 to second cell 218 and configured to allow container 216 to be transferred from first cell 217 to second cell 218 while maintaining at least one seal between the first cell 217 and second cell 218. In one embodiment, interlock 241 includes decontamination equipment. In another embodiment, first cell 217 and interlock 241 may be communicatively interconnected, via sealable door 240, allowing container 216 to be transferred from first cell 217 to interlock 241. In a further embodiment, first cell 217 and second cell 218 include a roller conveyer 246 configured to allow containers 216 to be loaded thereon and transported within and/or between each cell. Referring again to FIG. 2, in some embodiments, second cell 218 includes a furnace 290 configured for heating container 216 in a bake-out process. In some embodiments, the bake-out process includes heating container 216 in furnace 290 to remove excess water and/or other materials, for example, at a temperature of about 400° C. to about 500° C. for several hours. In some embodiments, a vacuum is established on container 216 and any off-gas is removed from container 216 during the bake-out process. The off-gas may include air from container 216 and/or other gas released from the waste material during the bake-out process. In some embodiments, the off-gas removed from container 216 is routed through line 206, which may lead out of second cell 218 and may be connected to a further ventilation system. Line 206, in some embodiments, includes one or more filters 204 to capture particulates entrained in the off-gas. Filters 204 may include HEPA filters according to some embodiments. In further embodiments, line 206 includes one or more traps 219 for removing materials such as mercury that may not be desirable to vent. For example, trap 219 in one embodiment may include a sulfur impregnated carbon bed trap configured to trap mercury contained in the off-gas from container 216. In further embodiments, a vacuum is established in container 216 during the bake-out process and container 216 may then be sealed to maintain the vacuum. Evacuation of the air and/or other gas from container 216, in some embodiments, is achieved by coupling container 216 with an evacuation system. FIG. 13 illustrates an exemplary evacuation system that can be used in accordance with embodiments of the invention shown coupled to filling plug 640 of container 600 as described above herein. It should be understood that the evacuation system depicted in FIG. 13, in other embodiments, may be coupled to containers having other configurations. For example, the evacuation system may be coupled to evacuation port 560 of container 500 shown in FIGS. 5A and 6A. Referring again to FIG. 13, the evacuation system shown includes an evacuation nozzle 300, which may be coupled with an evacuation line or other a vacuum source. In some embodiments, evacuation nozzle 300 is further coupled to a vacuum transducer 301 configured to measure the vacuum level in container 600. In some embodiments, evacuation nozzle 300 is coupled to a valve 302. In some embodiments, valve 302 is configured to isolate container 600 from the vacuum source, which in turn allows for the detection of leaks in container 600 or detection of gas being evolved from interior volume 616. The detection can be accomplished, for example, by measuring pressure change (e.g. using vacuum transducer 301) as a function of time. An increase in pressure (or loss of vacuum) in container 600 over time may indicate, for example, a possible leak or gas generation from interior volume 616. In some embodiments, evacuation nozzle 300 further includes a filter configured to prevent passage of particulate matter there through. As illustrated, evacuation nozzle 300 in some embodiments is coupled to filling plug 650 and/or filling port 640 of container 600. In some embodiments, evacuation nozzle 300 its around filling plug 650 and filling port 640, in some embodiments, evacuation nozzle 300 is configured to at least partially surround filling plug 650 and filling port 640 when filling plug 650 is coupled with filling port 640. In some embodiments, evacuation nozzle 300 forms a circumferential seal with filling port 640 when coupled thereto. In some embodiments, evacuation nozzle 300 seats against flange 634. In some embodiments, evacuation nozzle 300 includes a gasket that engages with an external surface of filling port 640 to form a hermitic seal therewith when evacuation nozzle is coupled with filling port 640. In some embodiments, filling plug 650 may be threadably coupled with filling port 640 in a first open configuration to allow air and/or other gas to pass through filter 690 and between filling plug 650 and filling port 640 and in a second closed configuration to hermetically seal and close filling port 640. In some embodiments, air and/or other gas is allowed to pass between filling plug 650 and filling port 640 and through seam 646. In some embodiments, evacuation nozzle 300 is configured to withdraw air and/or other gas from interior volume 616 of container 600 when filling plug 650 and filling port 640 are in the first open configuration. In some embodiments, after air and/or other gas is withdrawn from interior volume 616, a vacuum is created within interior volume 616 and filling plug 650 is used to hermetically seal filling port 640 in the closed configuration so as to maintain the vacuum. In some embodiments evacuation nozzle 300 is fitted with a torque 304 having a stem 303. In some embodiments, stem 303 has a proximal end and a distal end, said distal end being configure to mate with a recess in filling plug 650, and the proximal end being coupled to a handle. In some embodiments, the handle of torque 304 is manipulated to threadably tighten filling plug 650 to filling port 640, thereby forming a tight seal between the filing plug 650 and filling port 640. In some embodiments, torque 304 is manipulated with a drive shaft. In some embodiments, when the bake-out process is completed, the vacuum is maintained, on container 600 through the evacuation system. In some embodiments, when the vacuum reaches a set point, the vacuum is verified, for example using vacuum transducer 301 as described above herein, and filling port 640 is dosed (e.g., hermetically sealed) by fling plug 650 and the evacuation system is removed. In some embodiments, filing plug 650 is then welded to filling port 640. In some embodiments, filling plug 650 is welded to filling port 640 by an orbital welder 242, which may be positioned in a welding station in second cell 218. An embodiment of an orbital welding station is illustrated, in FIG. 14, which shows orbital welder 242 configured to weld filling plug 650 onto filling port 640 of container 600 at seam 646. In some embodiments, orbital welder 242 is remotely operated. In some embodiments, welds applied by orbital welder 242 are visually inspected. While the foregoing description of the evacuation system and orbital welder 242 makes reference to container 600, it should be understood that these elements may be similarly used on other configurations for container 216. For example, in other embodiments, these elements may be similarly used to evacuate, seal, and weld container 500 at evacuation port 560. In these embodiments, where container 500 also includes a separate filling port 540, filling port 540 may be similarly closed (e.g., by filling plug 550) and welded scaled by orbital welder 242 prior to the bake-out process. With reference again to FIG. 2, following the bake-out process, container 216, in some embodiments, is placed in containment 231 after being removed from furnace 290. In some embodiments, containment 231 provides for further contamination control in case of leakage or rupture of container 216. In some embodiments, containment 231 may be pie-staged on roller conveyor 246 for subsequent transport to third cell 232. III. Third Cell Exemplary embodiments of third cell 232 are illustrated in FIGS. 3, 4 and 15, in one embodiment, third cell 232 is a HIP process cell which allows for hot isostatic pressing of container 216. In one embodiment, third cell 232 includes a hot isostatic pressing station. In one embodiment, first cell 217 is held at a first pressure P1, second cell 218 is held at a second pressure P2 and third cell 232 is held at a third pressure P3. In one embodiment, first pressure P1 is less than second pressure P2 which is less than third pressure P3. Referring to FIGS. 3, 4 and 16, in one embodiment, modular system 400 in accordance with the present invention includes third cell 232, wherein third cell 232 is isolated from first cell 217 and second cell 218, and wherein second cell 218 and third cell 232 are configured to allow container 216 to be transferred from second cell 218 to third cell 232. In some embodiments, container 216 is transferred from second cell 218 to third cell 232 in containment 231. In some embodiments, container 216 is subjected to hot isostatic pressing in third cell 232. In some embodiments, container 216 is subjected to hot isostatic pressing while in containment 231. In some embodiments, third cell 232 includes a hot isostatic pressing station 249. In one embodiment, hot isostatic pressing station 249 includes a HIP support frame 245, a hot isostatic pressing vessel 251 secured to support frame 245, and a pedestal mounted pick and place machine (robotic arm) 252 secured to the HIP support frame 245, robotic arm 252 configured to manipulate within hot isostatic pressing station 249. In one embodiment, robotic arm 252 is configured to lift and transfer container 216 from roller conveyer 246 into isostatic process vessel 251. In a further embodiment, third cell 232. Includes a sealable door 240. In one embodiment, scalable door 240 couples third cell 232 and second cell 218 and is configured to allow container 216 to be transferred from second cell 218 to third cell 232. In a further embodiment, second cell 218 and third cell 232 each include a roller conveyer 246 configured to allow container 216 to be loaded thereon and transported within and/or between second 218 and third cell 232. Hot isostatic pressing, according to some embodiments, includes positioning containment 231 holding container 216 in a hot isostatic pressing vessel 251. In some embodiments, container 231 is positioned by robotic arms 252. In some embodiments, the hot isostatic pressing vessel 251 is provided with an argon atmosphere (e.g., from argon source 236 via argon line 202) which can be heated and pressurized. In some embodiments, for example, the hot isostatic pressing process is performed by heating containment 231 holding container 216 to about 1000° C. to about 1250° C. in the hot isostatic pressing vessel 251 for about 2 hours to about 6 hours. In some embodiments, the pressure inside the hot isostatic pressing vessel 251 is controlled to be about 4300 psi to about 15000 psi during the hot isostatic pressing process. In some embodiments, compressors (e.g., 234) protected by in-line filtration are used to control the argon atmosphere of the hot isostatic pressing vessel 251. In some embodiments, the argon used during the hot isostatic pressing process is filtered and stored in a manner that conserves both argon and pressure. Referring to FIG. 2, in some embodiments, the argon is recycled to argon source 236 via pump 238. The recycled argon, in some embodiments, passes through filter 233. With reference to container embodiments illustrated in FIGS. 5A, 5B, 6A and 6B, the material of filter 590 and/or filter 690 is chosen so that upon heating during hot isostatic pressing the filter densities into a solid and non-porous material forming a weld with container, container evacuation port and/or container filling port. In some embodiments, the material of filter 590 and/or 690 is chosen wherein at a filling temperature filter 590 and/or 690 is porous to air and/or gas but densities into a non-porous material during hot isostatic pressing. In some embodiments, after hot isostatic pressing is complete, containment 231 and container 216 is allowed to cool within the hot isostatic pressing vessel 251 to a temperature sufficient for removal (e.g., about 600 EC). In some embodiments, hot isostatic pressing vessel 251 includes a cooling jacket having cooling fluid (e.g., water) flowing therethrough. In some embodiments, the cooling jacket is supplied with cooling water at a rate of about 80 gpm to about 100 gpm. In some embodiments, containment 231 holding container 216 is removed from hot isostatic pressing vessel 251 and transferred to a cooling cabinet for cooling. In some embodiments, the cooling cabinet is supplied with a cooling fluid (e.g., water). In some embodiments, the cooling cabinet is supplied with cooling water at a rate of about 10 gpm, in some embodiments, containment 231 and container 216 are allowed to cool in the cooling cabinet for about 12 hours. Following cooling in the cooling cabinet, containment 231 holding container 216 is placed on a roller conveyor 246 for transport to fourth cell 230. IV. Fourth Cell Exemplary embodiments of fourth cell 230 are illustrated in FIGS. 3, 4 and 17. In one embodiment, fourth cell 230 is a cooling cell which allows for further cooling of container 216 after the hot isostatic pressing (HIP) process. In some embodiments, container 216 is packaged in fourth cell 230 for subsequent storage. In a further embodiment, referring to FIGS. 3, 4 and 17, modular system 400 in accordance with the present invention includes fourth cell 230, which may be a cooling cell. In one embodiment, fourth cell 230 is isolated from first 217, second cell 218 and third cell 220. In one embodiment, third 232 and fourth cell 230 are configured to allow container 216 to be transferred from third cell 232 to fourth cell 230. In one embodiment, first cell 217 is held at a first pressure P1, bake-out and second cell 218 is held at a second pressure P2, third cell 232 is held at a third pressure P3 and fourth cell 230 is held at a fourth pressure P4. In one embodiment, first pressure P1 is less than second pressure P2 which is less than third pressure P3 which is less than fourth pressure P4. In a further embodiment, fourth cell 230 includes a moveable shielded isolation door 240. In one embodiment, sealable door 240 is coupled to fourth cell 230 and third cell 232 and is configured to allow container 216 to be transferred from third cell 232 to fourth cell 230. In a further embodiment, each of third cell 232 and fourth cell 230 includes a roller conveyer 246 configured to allow container 216 to be loaded thereon and transported within and/or between third cell 232 and fourth cell 230. In yet another embodiment, fourth cell 230 includes an orbital welder 255. In some embodiments, after transport to fourth cell 230, containment 231 is opened and container 216 checked for evidence of container failure deformation, expansion, breakage, etc.). In the event of failure of container 216, according to some embodiments, container 216 and containment 231 are moved to a decontamination chamber within fourth cell 230, decontaminated and returned to second cell 218 for possible recovery. If there is no evidence of failure of container 216, container 216 is removed from containment 231 and transferred to a cooling and packing station 250 in fourth cell 230 according to some embodiments. In a further embodiment, cooling and packing station 250 includes a set of at least one or more cooling stations. In one embodiment, at least one or more cooling stations 253 configured to receive and hold processed container 216 for final cooling. In some embodiments, container 216 is passively cooled in cooling station 253. In some embodiments, container 216 is actively cooled in cooling station 253. In some embodiments, after final cooling, container 216 is packaged in fourth cell 230 for transport and storage. In some embodiments, one or more cooled containers 216 are placed in a canister. In some embodiments, the canister containing one or more containers 216 is then welded shut, for example, using an orbital welder 255. In some embodiments, the canister can then be transported for storage. Referring to FIG. 2, any one of the cells of the modular system 400 may include any suitable number of vacuum lines, including no vacuum line at all. As illustrated in FIG. 2, first cell 217, second cell 218, third cell 232 and fourth cell 230 may each include a set of one or more vacuum lines. Moreover as illustrated in FIGS. 2, 3, 4, 5 and 10, first cell 217, second cell 218, third cell 232 and fourth cell 230 may each be equipped with a set of at least one or more remotely operated overhead bridge cranes 239. In one embodiment, in addition to their material handling roles, each of these remotely operated overhead bridge cranes 239 are designed to be available for use in accomplishing either remote or manned maintenance of the equipment within the various cells. In another embodiment, each of the in-cell cranes may be configured to be capable of being remotely removed from the cell via a larger crane provided for maintenance purposes. In some embodiments, secondary waste produced by modular system 400 of the present invention may be collected and transferred to containers 216 for processing in accordance with steps of process flow 200. In some embodiments, for example, secondary waste is added to feed blender 212, mixed with calcined materials and/or additives, and transferred to a container 216 via a filling nozzle for subsequent hot isostatic pressing. Secondary waste, as used herein according to certain embodiments, refers to hazardous waste materials which are removed from container 216 and/or materials which are contaminated with hazardous waste materials during steps of the present invention. In some embodiments, the secondary waste is converted to a form suitable for transferring via the filling nozzle before introducing the secondary waste into a container 216. In some embodiments, secondary waste includes materials filtered or trapped from the off gases evacuated from container 216. In one such embodiment, secondary waste includes mercury captured from off gas evacuated from a container 216 during processing, for example, by one or more traps 219 as described above herein. The mercury may be transformed into an amalgam by mixing the mercury with one or more other metals and transferred to another container 216 for further processing according to one example of this embodiment. In some embodiments, secondary waste further includes system components which may have been contaminated by or in direct contact with hazardous waste material. The contaminated components may be combusted, crushed, pulverized, and/or treated in another manner prior to feeding to a container 216. In one such example, secondary waste includes a used cell or exhaust line filter (e.g., filter 204), which may contain hazardous waste materials, in some embodiments, the used filter may be combusted and the resulting ashes are fed to a container 216 for further processing. In some embodiments, at least 50% by weight of the secondary waste produced by modular system 400 is collected for processing. In some embodiments, at least 60% by weight of the secondary waste produced by modular system 400 is collected for processing. In some embodiments, at least 70% by weight of the secondary waste produced by modular system 400 is collected for processing, in some embodiments, at least 80% by weight of the secondary waste produced by modular system 400 is collected for processing. In some embodiments, at least 90% by weight of the secondary waste produced by modular system 400 is collected for processing, in some embodiments, at least 95% by weight of the secondary waste produced by modular system 400 is collected for processing. In some embodiments, at least 99% by weight of the secondary waste produced by modular system 400 is collected for processing. Method of Processing Hazardous Waste Using a Modular System In some embodiments, the systems, method and components described herein provide for a method of storing hazardous waste material comprising a plurality of steps and performed in a modular system. In some embodiments, one or more of the steps described herein can be performed in an automated manner. In a first cell, hazardous waste material is added to a container via a filling nozzle coupled to a filling port of the container. Various embodiments of such filling nozzle are described herein. The container is configured to scalingly contain the hazardous waste material. In one embodiment, the container further includes an evacuation port. In one embodiment, the container is evacuated prior to adding the hazardous waste material by connecting a filling nozzle having a connector coupled to a vacuum system to thereby place the container under a negative pressure. In another embodiment, the container is evacuated during adding of the hazardous waste material via an evacuation nozzle coupled to an evacuation port of the container to thereby maintain the container under a negative pressure during the adding step. In some embodiments, the amount of hazardous waste material added to the container is verified by measuring the weight of the container after filling. Various embodiments of weight verification systems are described herein. In some embodiments, the amount of hazardous waste material added to the container is verified by comparing the weight (or change in weight) of the container after filling to the weight of hazardous waste material prior to filling. In one embodiment, a filling plug is inserted into the filling port to form a plugged container after the hazardous waste material is added to the container to close the filling port. In another embodiment, a filling plug is inserted into the filling port and an evacuation plug is inserted into the evacuation port prior to sealing the filling port to form a plugged container. The plugged container is then transferred from the first cell to the second cell via the moveable shielded isolation door. In one embodiment, the plugged cell is transferred from the first cell to the second cell via the moveable shielded isolation door and then into an interlock area containing contamination equipment. In the second cell, the plugged container is connected to an evacuation nozzle coupled to an evacuation system and the container is heated. In some embodiments, the container is heated in a bake-out furnace to remove excess water and/or other materials. In some embodiments, off-gas including air and/or other gas is removed from container during heating, for example, through the use of the evacuation nozzle, in one embodiment, the evacuation nozzle is coupled to the evacuation port of the container. In such an embodiment, the evacuation plug is closed while the evacuation nozzle is couple to the evacuation nozzle. In one such embodiment, the evacuation port includes an evacuation plug which is threadably coupled to the evacuation port. The evacuation plug allows air and/or gas to pass through a filter, located in the evacuation port, and between the evacuation plug and the evacuation port in a heating configuration. Prior to heating the container, the evacuation port is at least partially opened. The container is then heated. Following the heating step, the evacuation port is placed in a closed configuration and is sealed in one embodiment. In one such embodiment, the vacuum on the container is maintained for a period of time following the heating step prior to sealing. Optionally, the maintenance of the vacuum in the container is verified. In one such embodiment, the sealing step is performed by welding an evacuation plug to the evacuation port to seal the evacuation port. In such an embodiment, the welding is performed using an orbital welder. In another embodiment, the evacuation nozzle is coupled to the filling port of the container, in such an embodiment, the filling plug is closed while the evacuation nozzle is couple to the evacuation nozzle. In one such embodiment, the filling port includes a filling plug which is threadably coupled to the filling port. The filling plug allows air and/or gas to pass through a filter, located in the filling plug, and between the filling plug and the filling port in a heating configuration. Prior to heating the container, the filling port is at least partially opened. The evacuated container is then heated. Following the heating step, the filling port is closed in a closed configuration and is sealed. In one such embodiment, the vacuum on the container is maintained for a period of time following the heating step prior to sealing. Optionally, the maintenance of the vacuum in the container is verified, in one such embodiment, the sealing step is performed by welding the filling plug to the filling port to seal the filling port. In such an embodiment, the welding is performed using an orbital welder. Following the sealing step, the sealed container is transferred from the second cell to the third cell via a second moveable shielded isolation door. In some embodiments, the sealed container is transferred from the second cell to the third cell inside a containment. The sealed container is then subjected to hot isostatic pressing. In some embodiments, the sealed container is subjected to hot isostatic pressing while inside the containment. In some embodiments, hot isostatic pressing includes subjecting the sealed container to a high temperature, high pressure argon atmosphere. In some embodiments, the sealed container is initially cooled in a cooling cabinet after hot isostatic pressing. Following the hot isostatic pressing, the container is transferred from the third cell to the fourth cell via a third moveable shielded isolation door. In the fourth cell, according to seine embodiments, the container undergoes final cooling. In further embodiments, the container is packaged in a canister for transport and storage. It will be appreciated by those skilled in the art that changes could be made to the exemplary embodiments shown and described above without departing from the broad inventive concept thereof. It is understood, therefore, that this invention is not limited to the exemplary embodiments shown and described, but it is intended to cover modifications within the spirit and scope of the present invention as defined by the claims. For example, specific features of the exemplary embodiments may or may not be part of the claimed invention and features of the disclosed embodiments may be combined. Unless specifically set forth herein, the terms “a”, “an” and “the” are not limited to one element but instead should be read as meaning “at least one”. It is to be understood that at least some of the figures and descriptions of the invention have been simplified to focus on elements that are relevant for a clear understanding of the invention, while eliminating, for purposes of clarity, other elements that those of ordinary skill in the art will appreciate may also comprise a portion of the invention. However, because such elements are well known in the art, and because they do not necessarily facilitate a better understanding of the invention, a description of such elements is not provided herein. Further, to the extent that the method does not rely on the particular order of steps set forth herein, the particular order of the steps should not be construed as limitation on the claims. The claims directed to the method of the present invention should not be limited to the performance of their steps in the order written, and one skilled in the art can readily appreciate that the steps may be varied and still remain within the spirit and scope of the present invention.
042232295	claims	1. An oral radiation protector appliance for protecting human anatomy against harmful side effects of radiation therapy comprising an intraoral portion and an extraoral portion, said portions being formed of material substantially impervious to penetration therethrough of radiation rays, said intraoral portion substantially covering and protecting the frontal, upper and rear surfaces of the teeth, the gingiva and periodontal bone, the extraoral portion covering extraoral areas of the face and protecting the parotid and sublingual and salivary glands. 2. An oral radiation protector as claimed in claim 1, said intraoral portion being substantially U-shaped to encompass the teeth and adjacent anatomy areas of a patient. 3. An oral radiation protector as claimed in claim 1, said intraoral portion including substantially U-shaped upper and lower sections joined in back to back relationship to encompass the upper and lower teeth and adjacent anatomy areas of a patient. 4. An oral radiation protector as claimed in claim 1, said material in said intraoral portion including a layer of radiation shielding material and a covering of a plastic material. 5. An oral radiation protector as claimed in claim 1, said material in said intraoral portion including a lead sheet and a coating of a plastic material thereover. 6. An oral radiation protector as claimed in claims 1 or 5, said material of said extraoral portion including a lead sheet. 7. An oral radiation protector as claimed in claims 1, 2 or 3, wherein said intraoral portion includes a projection thereon extending forwardly and external of the mouth of a patient, said extraoral portion having an opening therethrough for detachable mounting attachment of said extraoral portion on said projection. 8. An oral radiation protector appliance for protecting teeth, gingiva, periodontal or alveola bone, salivary glands, and adjacent body areas, of a patient against harmful radiation therapy side effects comprising an intraoral member and an extraoral member, said extraoral member being selectively attachable to and detachable from said intraoral member for selected combined appliance usage, or for separate use of said intraoral member, said intraoral member substantially covering the teeth, gingiva, periodontal or alveolar bone, and said extraoral member substantially covering extraoral anatomy of the face to protect the parotid and sublingual and salivary glands. 9. An appliance as claimed in claim 8, said intraoral and said extraoral members respectively having coacting means for joining said members externally of a patients mouth. 10. An appliance as claimed in claim 9, said coacting means comprising a projection on said intraoral member adapted for extension externally of a patient's mouth and an opening through said extraoral member into which said projection is insertable to thereby mount and attach said extraoral member on said intraoral member. 11. A radiation protective shield for preventing direct impingement of radiation rays on teeth, dentine, alveolar bone, and adjacent body tissues of a person being subjected to radiation therapy, comprising an intraoral shield portion and an extraoral shield portion, said intraoral portion including at least in part a radiation shielding material, having a shape conforming to the curvilinear configuration of a human dentition and adapted for disposition within the mouth of the person, and with at least a front portion thereof interposed between the inner sides of the mouth lip portions and forward sides of the teeth and associated gingiva and alveolar bone, the intraoral shield having a depth serving to substantially cover the upper and lower sets of dentitions and tissues and bone associated with the teeth, said extraoral shield, consisting of a curvilinear shaped sheet of radiation shielding material and being selectively attachable to and supportable by said intraoral shield and disposed thereby externally of the mouth of the person, said extraoral portion being of shape and size to cover a substantial area of the extraoral anatomy of the face of the person to thereby intercept rays and prevent direct and/or stray impingement thereon. 12. A radiation protective shield as claimed in claim 11, said intraoral shield including upper and lower channel shaped members adapted to substantially contain within the physical dimensions thereof the upper and lower gingival, teeth, aleveolar bone and adjacent areas of a user person, the channel shaped members being medially connected and opening respectively upwardly and downwardly, and thereby engageable over and encompassing the upper and lower teeth sets. 13. A radiation protective shield as claimed in claim 12, said intraoral shield having a frontal projection thereon adapted for external projection from the persons mouth, said extraoral shield having an opening therein engageable with said projection and constituting a support for said extraoral shield. 14. A radiation protective shield as claimed in claim 13, said material including a lead sheet, said intraoral shield being coated with a plastic material to prevent tooth and internal mouth contact with the lead material. 15. A radiation protective shield as claimed in claim 14, the plastic material coating on said intraoral shield being of soft and resilient texture but of a strength to normally prevent penetration by the teeth of the person.
	abstract	An ECP sensor includes a tubular ceramic probe having a closed tip at one end packed with a metal and metal oxide powder. A metal support tube receives an opposite end of the probe, and is joined thereto by a braze joint therewith. An electrical conductor extends through the support tube and probe, and has an end buried in the powder for electrical contact therewith. A ceramic band bridges the probe and tube at the joint for sealing thereof.
	claims	1. An apparatus for spatially modulating an x-ray beam propagating in a beam direction and exhibiting a 2D radiation field, comprising:a carrier;a plurality of planar attenuation elements for x-ray radiation disposed in a 2D grid on said carrier substantially perpendicular to the beam direction and within said 2D radiation field each of said attenuation elements being a piezoelectric flex transducer having one end thereof fastened in said carrier;at least one piezoelectric actuator in mechanical engagement with each attenuation element for piezoelectrically displacing that attenuation element independently of all others of said attenuation elements to attenuate a portion of said x-ray beam in said 2D radiation field, the mechanically engaged attenuation element and piezoelectric actuator forming an element/actuator combination, and each of said attenuation elements and each of said actuators having a piezoelectrically influenced region exhibiting a piezoelectrically-caused change selected from the group consisting of a length change, a width change and a position change; andat each element/actuator combination, a sensor in mechanical contact with one of the piezoelectrically influenced regions of that element/actuator combination for detecting said piezoelectrically caused change and generating an electrical signal corresponding thereto. 2. An apparatus as claimed in claim 1 wherein said carrier is a substrate composed of material that is transparent to x-ray radiation. 3. An apparatus as claimed in claim 1 wherein said carrier comprises a substrate penetrated by a plurality of non-intersecting passage channels, with one element/actuator combination being disposed in each of said passage channels. 4. An apparatus as claimed in claim 3 wherein said passage channels are disposed parallel to each other in said carrier. 5. An apparatus as claimed in claim 3 wherein said x-ray radiation emanates from a focus, and wherein said passage channels are aligned in said carrier to said focus. 6. An apparatus as claimed in claim 3 wherein said attenuation elements are mounted in the respective passage channels so that a maximum of said piezoelectrically-caused position change causes the actuation element to completely close the passage channel in which it is disposed. 7. An apparatus as claimed in claim 3 wherein each of said passage channels has an inner wall, and wherein each of said attenuation elements has first and second oppositely disposed, substantially parallel primary surfaces, and wherein each element/actuator combination comprises one attenuation element and two piezoelectric actuators respectively disposed between said first and second primary surfaces and the inner wall of the passage channel in which the actuator/element combination is disposed, said two piezoelectric actuators being offset from each other for tilting the attenuation element around a central axis. 8. An apparatus as claimed in claim 7 wherein each of said piezoelectric actuators is a piezo-stack actuator. 9. An apparatus as claimed in claim 1 wherein each sensor is a tensiometer strip. 10. An apparatus as claimed in claim 1 wherein each of said attenuation elements is plate-shaped. 11. An apparatus as claimed in claim 1 wherein each attenuation element is comprised of a metallic material that strongly absorbs x-ray radiation. 12. An apparatus as claimed in claim 1 wherein each attenuation element comprises an element body coated with a metallic material that strongly absorbs x-ray radiation. 13. An apparatus for spatially modulating an x-ray beam propagating in a beam direction and exhibiting a 2D radiation field, comprising:a carrier;a plurality of planar attenuation elements for x-ray radiation disposed in a 2D grid on said carrier substantially perpendicular to the beam direction and within said 2D radiation field;at least one piezoelectric actuator in mechanical engagement with each attenuation element for piezoelectrically displacing that attenuation element independently of all others of said attenuation elements to attenuate a portion of said x-ray beam in said 2D radiation field, the mechanically engaged attenuation element and piezoelectric actuator forming an element/actuator combination, and each of said attenuation elements and each of said actuators having a piezoelectrically influenced region exhibiting a piezoelectrically-mused change selected from the group consisting of a length change, a width change and a position change;each of said attenuation elements being a self-supporting element and each of said piezoelectric actuators being a piezoelectric flex transducer, fastened at a first end thereof on said carrier and having an opposite second free end to which the attenuation element in the element/actuator combination is attached substantially parallel to the flex transducer; andat each element/actuator combination, a sensor in mechanical contact with one of the piezoelectrically influenced regions of that element/actuator combination for detecting said piezoelectrically caused change and generating an electrical signal corresponding thereto. 14. An apparatus as claimed in claim 13 wherein said carrier is a substrate composed of material that is transparent to x-ray radiation. 15. An apparatus for spatially modulating an x-ray beam propagating in a beam direction and exhibiting a 2D radiation field, comprising:a carrier;a plurality of planar attenuation elements for x-ray radiation disposed in a 2D grid on said carrier substantially perpendicular to the beam direction and within said 2D radiation field;at least one piezoelectric actuator in mechanical encasement with each attenuation element for piezoelectrically displacing that attenuation element independently of all others of said attenuation elements to attenuate a portion of said x-ray beam in said 2D radiation field, the mechanically engaged attenuation element and piezoelectric actuator forming an element/actuator combination, and each of said attenuation elements and each of said actuators having a piezoelectrically influenced region exhibiting a piezoelectrically-caused change selected from the group consisting of a length change, a width change and a position change;at each element/actuator combination, a sensor in mechanical contact with one of the piezoelectrically influenced regions of that element/actuator combination for detecting said piezoelectrically caused chance and generating an electrical signal corresponding thereto; andeach element/actuator combination being formed as a flex transducer and each sensor comprising a piezoelectric layer integrated into the flex transducer. 16. An x-ray imaging system comprising:an x-ray source that emits an x-ray beam propagating in a beam direction and exhibiting a 2D radiation field;a laminar x-ray detector disposed in a path of said x-ray beam, said x-ray source and said x-ray detector defining an examination volume therebetween, said laminar x-ray detector emitting electrical signals dependent on said 2D radiation field incident thereon, collectively representing an x-ray image;a spatial modulator disposed in said x-ray beam at an x-ray source-proximate side of said examination volume, said spatial modulator comprising a carrier, a plurality of planar attenuation elements for x-ray radiation disposed in a 2D grid on said carrier substantially perpendicular to the beam direction and within said 2D radiation field, at least one piezoelectric actuator in mechanical engagement with each attenuation element for piezoelectrically displacing that attenuation element independently of all others of said attenuation elements to attenuate a portion of said x-ray beam in said 2D radiation field, the mechanically engaged attenuation element and piezoelectric actuator forming an element/actuator combination, and each of said attenuation elements and each of said actuators having a piezoelectrically influenced region exhibiting a piezoelectrically-caused change selected from the group consisting of a length change, a width change and a position change, and at each element/actuator combination, a sensor in mechanical contact with one of the piezoelectrically influenced regions of that element/actuator combination for detecting said piezoelectrically-caused change and generating an electrical signal corresponding thereto;a controller connected to each of said actuators for selectively displacing said attenuation elements independently of each other; andan image processing device supplied with the electrical signals from said laminar x-ray detector and the electrical signals from said sensors, said image processing device normalizing said x-ray image dependent on said signals from said sensors. 17. An x-ray imaging system as claimed in claim 16 comprising a control loop in which said controller is connected with the respective sensors and the respective actuators of each element/actuator combination, said controller using the electrical signal from the sensor for that element/actuator combination as a representation of an actual position of the attenuation element thereof, and controlling the piezoelectric actuator of that element/actuator combination to set the attenuation element thereof at a selected position. 18. An x-ray imaging system as claimed in claim 16 wherein said laminar x-ray detector emits electrical signals dependent on the x-ray radiation incident thereon, and wherein said controller is connected to said x-ray detector and receives the electrical signals therefrom, and controls actuation of the respective actuation elements dependent on the electrical signals from said laminar x-ray detector. 19. An x-ray imaging system as claimed in claim 18 wherein the electrical signals from said laminar x-ray detector collectively represent an x-ray image, and wherein said controller controls said actuators dependent on said electrical signals from said laminar x-ray detector to produce a maximum number of distinguishable grey scale values in said x-ray image. 20. An apparatus for spatially modulating an x-ray beam, comprising:a carrier comprising a substrate penetrated by a plurality of non-intersecting passage channels, each of said passage channels having an inner wall;a plurality of planar attenuation elements for x-ray radiation disposed in a 2D grid on said carrier, each of said attenuation elements having first and second oppositely disposed, substantially parallel primary surfaces;two piezoelectric actuators in mechanical engagement with each attenuation element for piezoelectrically displacing that attenuation element independently of all others of said attenuation elements, the mechanically engaged attenuation element and piezoelectric actuators forming an element/actuator combination, with one element/actuator combination being disposed in each of said passage channels of said carrier with the two piezoelectric actuators engaged therewith being respectively disposed between said first and second primary surfaces and the inner wall of the passage channel in which the actuator/element combination is disposed, said two piezoelectric actuators being offset from each other for tilting the attenuation element around a central axis; andat each element/actuator combination, a sensor in mechanical contact with one of the piezoelectrically influenced regions of that element/actuator combination for detecting said piezoelectrically caused change and generating an electrical signal corresponding thereto. 21. An apparatus as claimed in claim 20 wherein each of said piezoelectric actuators is a piezo-stack actuator. 22. An x-ray imaging system comprising:an x-ray source that emits x-ray radiation;a laminar x-ray detector disposed in a path of said x-ray radiation and emitting electrical signals dependent on said x-ray radiation incident thereon, said x-ray source and said x-ray detector defining an examination volume therebetween;a spatial modulator disposed in said x-ray radiation at an x-ray source-proximate side of said examination volume, said spatial modulator comprising a carrier, a plurality of planar attenuation elements for x-ray radiation disposed in a grid on said carrier, at least one piezoelectric actuator in mechanical engagement with each attenuation element for piezoelectrically displacing that attenuation element independently of all others of said attenuation elements, the mechanically engaged attenuation element and piezoelectric actuator forming an element/actuator combination, and each of said attenuation elements and each of said actuators having a piezoelectrically influenced region exhibiting a piezoelectrically-caused change selected from the group consisting of a length change, a width change and a position change, and at each element/actuator combination, a sensor in mechanical contact with one of the piezoelectrically influenced regions of that element/actuator combination for detecting said piezoelectrically-caused change and generating an electrical signal corresponding thereto;a controller connected to each of said actuators for selectively displacing said attenuation elements independently of each other; andan image processing device supplied with the electrical signals from said laminar x-ray detector and the electrical signals from said sensors, said image processing device normalizing said x-ray image dependent on said signals from said sensors.
053533194	abstract	A removable feedwater sparger assembly includes a sparger having an inlet pipe disposed in flow communication with the outlet end of a supply pipe. A tubular coupling includes an annular band fixedly joined to the sparger inlet pipe and a plurality of fingers extending from the band which are removably joined to a retention flange extending from the supply pipe for maintaining the sparger inlet pipe in flow communication with the supply pipe. The fingers are elastically deflectable for allowing engagement of the sparger inlet pipe with the supply pipe and for disengagement therewith.
	claims	1. A label-free method for characterizing an interaction between a first unlabeled biomolecular particle and a second unlabeled biomolecular particle, the method comprising the steps of:providing an optical trap system, the optical trap system comprising a photonic crystal resonator having a light source directed thereto for exciting the photonic crystal resonator and a camera positioned above a trapping site in the photonic crystal resonator;radiating light from the light source in proximity of the trapping site in the photonic crystal resonator;optically trapping the first unlabeled biomolecular particle with a first known refractive index in the photonic crystal resonator using light with a specific minimum power from the light source to induce trapping;wherein the first unlabeled biomolecular particle has a known radius, R0;obtaining a first measurement of Brownian motion while the first unlabeled biomolecular particle is in the photonic crystal resonator based on light scattering captured by the camera from the first unlabeled biomolecular particle;introducing the second unlabeled biomolecular particle with a second known refractive index into the photonic crystal resonator;incubating the first and second unlabeled biomolecular particle under conditions suitable for binding said first and second unlabeled biomolecular particle to form a complex, wherein the second unlabeled biomolecular particle has a potential affinity for the first unlabeled biomolecular particle;wherein the the first unlabeled particle has a second radius, R′ and R′−R0=ΔR;optically trapping the first unlabeled biomolecular particle in the photonic crystal resonator using light with the specific minimum power from the light source to induce trapping after incubation;wherein the first unlabeled biomolecular particle is a virus and the second unlabeled biomolecular particle is an antibody;obtaining a second measurement of Brownian motion of the first unlabeled particle in the photonic crystal resonator after incubation based on light scattering captured by the camera from the first unlabeled biomolecular particle;obtaining a relative Brownian motion measurement, defined as a comparison of the first and second measurements of Brownian motion, of the first unlabeled particle after incubation and based on light scattered by the first unlabeled particle captured by the camera;analyzing a relationship between the relative Brownian motion measurement of the first unlabeled particle after incubation and ΔR; anddetermining, using the relationship of the relative Brownian motion measurement of the first unlabeled particle with respect to ΔR, a Brownian motion measurement of the photonic crystal resonator;wherein said relationship provides indication whether a complex is formed.
	summary
	abstract	A computer-implemented method for evaluating tool performance is described which includes maintaining tool history data in an electronic memory, updating the tool history data with tool servicing data, determining from the tool history and servicing data a predicted tool remaining useful life, and displaying the predicted useful life on a computer output device. Average tool data is compared to tool benchmark data to determine tool efficiency. Tool servicing, performance and efficiency data are maintained in a spreadsheet format. Data entered into one spreadsheet is used to update a plurality of spreadsheets. The spreadsheet format allows manufacturers to keep abreast of tool performance over time and in a plurality of locations and to anticipate tool rebuild and replacement requirements.
	description	Not Applicable Not Applicable 1. Field of Invention This invention relates to radiation shielding for the targeting assembly of a cyclotron or particle accelerator used in a radiopharmaceutical or radioisotope production system. More specifically, the present invention is related to a closure which is mounted on the housing of a particle accelerator or cyclotron, and which serves as radiation shielding for, and provides access to, such targeting assembly. 2. Description of the Related Art Positron Emission Tomography (PET) is a powerful diagnostic tool which allows the imaging of biological functions and physiology. PET utilizes short-lived radioactive isotopes, commonly referred to as tracers, which are injected into a patient's body. These radioisotopes are produced by radioisotope production systems which incorporate particle accelerators or cyclotrons. The particle accelerators produce radioisotopes by accelerating a particle beam and bombarding a target material. The typical particle accelerator used for producing PET radioisotopes includes a targeting assembly which is accessible from outside of the housing of the accelerator, and generally through an access opening in the housing, such that the target material can be replaced and such that maintenance can be performed on the targeting assembly. In order to protect those operating and maintaining the accelerator from the radiation emanating from the accelerator, the entire accelerator is placed in a shielded enclosure. For example, such shielded enclosures often take the form of a shell which surrounds the accelerator or cyclotron, with the shell being provided with movable portions or doors to provide access to the accelerator. The shielded enclosures typically include a high-Z shielding material, such as lead, adjacent the accelerator to moderate neutron energy and shield against gamma radiation, and a low-Z outer shielding, such as concrete, to absorb neutrons and, again, to provide gamma shielding. Commonly, the high-Z shielding defines a greater thickness proximate the targeting system of the accelerator given the neutron energy typically emanating therefrom. Generally, such shielded enclosures provide the only shielding about the targeting assembly of the accelerator such that when the shielded enclosures are removed or opened the targeting assemblies are accessible, but unshielded. Further, typical shielding enclosures for particle accelerators have a gap greater than one, inch (>1″) between the shielding and the accelerator/target assembly. This is due to the manufacturing tolerances of the shielding materials involved, and the methods for shield motion. Neutrons can be transported through these gaps without being moderated, allowing higher radiation doses outside the shield assembly. An example of one approach to providing shielding for an accelerator used in conjunction with a radioisotope production system is disclosed in U.S. Pat. No. 6,392,246 B1. The apparatus disclosed therein provides an outer housing which shields not only the accelerator, but various other components of the radioisotope production system. Further, U.S. Pat. No. 5,037,602 discloses a radioisotope production facility, and discusses the need for thick shielding around the accelerator to confine radiation. See also, U.S. Pat. Nos. 6,433,495 B1; 5,874,811; 5,482,865; and 4,646,659. Radioisotope production systems are commonly located in hospitals and other healthcare facilities such that the radioisotopes are readily available for use in medical imaging. Accordingly, it is imperative that proper radiation shielding be provided to protect not only the operators of the system and the medical staff, but the public. However, the need for thick radiation shielding around the accelerator tends to make radioisotope production systems large, space consuming systems, and the shielding tends to be very heavy. The size and weight of the radioisotope production systems tends to limit the nature of the facilities in which the systems can be placed, and often the construction of special facilities to accommodate the systems is necessary. Thus, it is advantageous to limit the thickness of the shielding surrounding the accelerator to the extent that it can be done without compromising the effectiveness of the shielding. Further, particularly where the radioisotope production system is placed in a healthcare facility, the exposure of the targeting system when the shielded enclosure surrounding the accelerator is removed can be particularly problematic. For example, where access to components of the accelerator other than those associated with the targeting system is required, the removal or the opening of the shielded enclosure leaves the targeting system unshielded, thereby unnecessarily increasing the level of radiation emanating from the accelerator. Additionally, it is advantageous to make shielding that conforms more closely to the accelerator and target envelope, to force the moderation of initially energetic neutrons. The present invention provides a closure for shielding, and selectively providing access to, the targeting assembly of the particle accelerator of a radioisotope production system. The typical radioisotope production system which utilizes the closure of the present invention includes a shielded enclosure which surrounds the particle accelerator and provides selective access to the particle accelerator. The closure of the present invention includes at least one door, and in one embodiment first and second doors, for selectively covering the opening in the housing of the particle accelerator. This closure, by virtue of being mounted directly on the accelerator, has a much smaller gap (<⅛″) between the shielding material of the closure and the accelerator, forcing the moderation of neutrons. This makes the additional shielding more effective, and, therefore, smaller and lighter than would otherwise be possible. The doors are movable from a closed position whereby the targeting assembly is shielded, to an open position whereby access to the targeting assembly is provided. In one embodiment, each first and second door is fabricated of copper. The closure also includes a door mounting assembly for mounting the doors on the housing of the particle accelerator. In one embodiment the door mounting assembly includes a frame for being secured about the opening in the particle accelerator accessing the targeting assembly. The door mounting assembly also including a first hinge assembly for pivotally securing the first door to the frame and a second hinge assembly for pivotally securing the second door to the frame, whereby the first and second doors of the closure selectively cover, and reduce radiation emissions from, the opening in the housing of the particle accelerator and the targeting assembly therein. Thus, the particle accelerator can be accessed by opening or removing the shielded enclosure surrounding the accelerator while maintaining radiation shielding over the targeting assembly. A closure for shielding, and selectively providing access to, the targeting assembly of a particle accelerator in accordance with the present invention is illustrated generally at 10 in FIGS. 1, 3–5 and 7. The closure 10 is used to shield the target assembly of the particle accelerator of a radioisotope production system. An example of a typical radioisotope production system of the type which would utilize the closure 10 is illustrated at 12 in FIGS. 2 and 3. As illustrated in FIG. 3, the radioisotope production system 12 incorporates a particle accelerator 14 enclosed in a housing 16, and includes a shielded enclosure 17 which surrounds the accelerator 14. In this particular system 12 the shielded enclosure 17 includes stationary shield assemblies 18 and 20 which are provided on opposite sides of the accelerator 14, and includes oppositely disposed movable shield assemblies 22 and 24 which can be moved away from the accelerator 14 to provide access to the accelerator. However, the particle accelerators with which the closure 10 can be used may utilize various shield enclosure configurations. Further, the illustrated particle accelerator 14 incorporates two target changers, and, accordingly, two closures 10 are utilized. It will, however, be understood that the closure 10 can be utilized with particle accelerators having single or multiple targeting assemblies. It will also be noted that the movable shield assemblies 22 and 24 include an inner shield 26 of high-Z shielding material, such as, for example, lead epoxy, and an outer shield 28l of low-Z shielding material, such as, for example, concrete. The closure 10 is provided with a door mounting assembly which, as will be discussed in detail below, facilitates the mounting of one or more doors for accessing the targeting assembly of an accelerator. As best illustrated in FIGS. 1 and 4 through 6, in one embodiment the door mounting assembly includes a frame 30 which is defined by a sill member 32, a header member 34, and opposite jamb members 36 and 38. The frame 30 is secured to the housing 16 of the particle accelerator 14 about an opening 40 (see FIG. 6) provided in the housing 16 through which the targeting assembly 42 of the accelerator 16 is accessed. The sill member 32, header member 34, and jamb members 36 and 38, are provided with counter sunk openings 39 which extend through the frame 30 and allow the frame 30 to be bolted to the housing 16 of the accelerator 14 with suitable bolts (not shown). As will be discussed further below, the frame 30 is fabricated from a suitable radiation shielding material. In one embodiment the shielding material used is copper, but other materials could be used. Mounted on the frame 30 is at least one closable door, and in the illustrated embodiment two doors 44 and 46 are mounted on the frame 30 such that the opening defined by the frame 30 can be selectively closed. The door 44 is pivotally secured to the frame 30 at its outboard edge 48 with a hinge assembly 50, and the door 46 is pivotally secured to the frame 30 at its outboard edge 52 with a further hinge assembly 54. The various components of the hinge assemblies 50 and 54 are fabricated of a strong, durable material, such as, for example, steel. As will be discussed further below, the doors 44 and 46 are fabricated from a suitable radiation shielding material, and in one embodiment the shielding material used is copper. However, other radiation shielding materials could be used. Moreover, it is contemplated that alternative door mounting assemblies could be used to mount the doors 44 and 46 on the particle accelerator instead of the frame 30. For example, the doors 44 and 46, or a single door, could be mounted directly on the housing 16 of the particle accelerator 14 using suitable hinge assemblies. In the illustrated embodiment, the sill member 32 defines a rabbet 56 along the upper portion of its front edge. The rabbet 56 receives the lower inner edge portions of the doors 44 and 46 when such doors are in a closed position. Also, the header member 34 defines a rabbet 58 along the lower portion of its front edge which receives the lower inner edge portions of the doors 44 and 46 when such doors are in a closed position. Further, the doors 44 and 46 are mounted such that they close over the front surfaces 60 and 62 of the jamb members 36 and 38, respectively. It will also be noted, as illustrated in FIG. 9, that the door 44 is provided with a rabbet 64 along the outside of its inboard edge, and the door 46 is provided with a rabbet 66 along the inside of its inboard edge, such that when the doors 44 and 46 are in a closed position the doors overlap proximate their inboard edges. Also, it will be noted that the sill member 32, the header member 34, and the jamb members 36 and 38 are matched dimensionally to the accelerator 14 and housing 16, providing substantially no gaps for radiation to emanate from or through. As a consequence of the use of the rabbets 56, 58, 64 and 66, and the positioning of the doors 44 and 46 over the front surfaces 60 and 62 of the jamb members 36 and 38, any radiation emanating from the targeting assembly 42, or the opening 40 in the housing 16, is intercepted by the radiation shielding material from which the doors 44 and 46, and the frame 30, are fabricated, and there are no openings or seams between the frame 30 and the doors 44 and 46 which would offer an unobstructed linear radiation path exiting the closure 10. The closure 10 is also provided with a locking mechanism which selectively secures the doors 44 and 46 in a closed position. It will be recognized by those of ordinary skill in the art that various locking mechanisms could be used, such as, for example, various latch or bolt mechanisms typically used to secure doors. However, in one embodiment the securing mechanism includes a pair of removable securing pins 68 and 70, which are received through holes 72 and 74 in the header member 34. The holes 72 and 74 register with holes in the doors 44 and 46 (only one such hole being shown at 76 in FIG. 8) when such doors are in a closed position. Accordingly, the doors 44 and 46 can being selectively secured in the closed position by inserting the pins 68 and 70 through the holes 72 and 74 in the header member 34, and into the holes 76 in the doors 44 and 46. To facilitate the removal of the pins 68 and 70, such pins are provided with pull rings 71. It is also anticipated that one or both of the doors 44 and 46 of the closure 10 can be provided with contoured inner surfaces which are configured to be closely received over components of the targeting assembly of the particular particle accelerator. For example, as illustrated in FIGS. 5 and 8, the door 46 is provided with an inner surface which defines a recess 78 which closely receives components of the targeting assembly 42. As noted above, in one embodiment the frame 30 and doors 44 and 46 of the closure 10 are made from copper. In this regard, testing has disclosed that the use of copper for such components of the closure 10 permits the thickness of the inner shield 26 of the shielded enclosure 17 to be reduced. For example, in tests to determine the desired relative thickness of the copper shielding material of the closure 10 and the lead epoxy shielding 26 of the shielded enclosure 17 necessary to maintain a 0.25 mrem/hr target radiation dose, the following results were obtained: Copper ThicknessLead Epoxy Thickness(cm)(cm)0402354306268231020Accordingly, whereas 40 cm of lead epoxy was required to maintain the target dose, by adding 10 cm of copper shielding over the target assembly, the thickness of the lead epoxy shielding could be reduced to 20 cm, reducing the combined thickness of the copper and lead epoxy shielding to 30 cm. Thus, whereas the thickness of the various components of the closure 10 can vary, it will be understood that the use of copper as the fabricating material for the closure 10 allows the combined thickness of the shielding for the accelerator to be reduced, allowing a reduction in the size of the radioisotope production system. This notwithstanding, it is contemplated that various other fabricating materials can be used for the components of the closure 10, such as, for example, stainless steel, lead, or aluminum, and it is contemplated that various alloys of copper could be used. Moreover, it is contemplated that the doors 44 and 46 could incorporate, and the frame 30, could incorporate layers of copper, or copper alloy, shielding rather than being fabricated entirely of copper, or a copper alloy. In light of the above, it will be recognized that the closure 10 provides a separate shielding for the targeting assembly 42 of the accelerator 14, while still allowing access to the targeting assembly. When the shielded enclosure 17 is opened, as in when the movable shield assemblies 22 and 24 are moved away from the accelerator 14, the targeting assembly 42 remains shielded by the closure 10. Accordingly, where access to the accelerator 14 is required, but not to the targeting assembly 42, the doors of the closure 10 can remain closed in order to reduce radiation emissions. Moreover, the use of a closure 10 fabricated of copper, or a copper alloy, permits the thickness of shielded enclosure 17 surrounding the accelerator to be reduced, thereby allowing the radioisotope production system 12 to be smaller in size. While the present invention has been illustrated by description of several embodiments and while the illustrative embodiments have been described in considerable detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of applicant's general inventive concept.
	summary
051165678	description	DESCRIPTION OF THE PREFERRED EMBODIMENTS In accordance with the present invention, a natural-circulation boiling-water reactor 100 comprises a vessel 102, a core 104, a chimney 106, a steam separator 108, and a dryer 110. Control rod drive housings 112 extend through the bottom of vessel 102 and support control rod guide tubes 113. Control rod guide tubes 113 extend to the bottom of core 104 so that control blades therein can be inserted into and retracted from core 104 to control its power output. Water flows, as indicated by arrows 114, into core 104 from below. This subcooled water is boiled within core 104 to yield a water/steam mixture which rises through chimney 106. Steam separator 108 helps separate steam from water, and the released steam exits through a steam exit 116 near the top of vessel 102. Before exiting, any remaining water entrained in the steam is removed by dryer 110. Water is returned down peripheral downcomer 118 by the force of the driving steam head provided by chimney 106. Feedwater enters vessel 102 through a feedwater inlet nozzle 120 and feedwater sparger 122 to replenish and to help cool the recirculating water in downcomer 118. Core 104 comprises a lower fuel matrix 124 and an upper fuel matrix 126. Upper fuel matrix 126 is filled with upwardly oriented fuel bundles 130, and lower fuel matrix 124 is filled with downwardly oriented fuel bundles 128. Fuel bundles 128 of lower matrix 124 are arranged in a two-dimensional array, as shown in FIG. 2. Fuel bundles 130 of upper matrix 126 are arranged in a similar array directly above. Spaces are left between groups of four fuel bundles for control rods 232 with cruciform cross sections to move vertically to regulate power output. Upper fuel bundles 130 are stacked on lower fuel bundles 128, as shown in FIG. 3. As schematically indicated in FIG. 3, each fuel bundle contains multiple fuel rods. Lower fuel bundle 128 includes fuel rods 302, and upper fuel bundle 130 includes fuel rods 304. Each lower fuel rod 302 includes a fuel section 306 and a plenum 308 which leaves space for gaseous byproducts of fission reactions to accumulate. Otherwise, pressure buildup within a fuel rod could lead to a breach of the fuel rod cladding. Note that fuel rods 302 are vertically oriented with their plenums 308 below their fuel sections 306. Likewise, upper fuel rods 304 are vertically oriented with their plenums 310 above their fuel sections 312. The inverted relationship of fuel bundles 128 and fuel bundles 130 thus defines a relatively continuous fuel section 314 between lower plenums 308 and upper plenums 310. This physical continuity provides a greater degree of thermal continuity and neutron flux continuity than would be provided if lower fuel bundles 128 were not inverted. Relative to fuel elements in one-level cores, there is less plenum space at a level with a two-phase flow. In particular, core 104 provides half of its plenum space near its entrance where almost all of the adjacent water is in the liquid phase. Thus, the present invention provides that more plenum space is adjacent to a single-phase water flow region, enhancing channel and core stability. The bi-level fuel bundle arrangement of the present invention provides additional flexibility in the redistribution of fuel bundles during refueling operations. In particular, a level as well as an array position can be selected for each fuel bundle. This provides for a refueling scheme in which fresh fuel bundles are installed in upper matrix 126 where a harder neutron spectrum can convert fertile fuel to fissile fuel. Partially spent fuel bundles can be moved from upper matrix 126 to lower matrix 124 where the more thermal neutron flux can more effectively utilize the remaining fissile fuel. Fertile fuel conversion is minimized in the lower matrix so that a relatively complete burnup is possible, minimizing the quantity of high-level radioactive waste products in the fuel bundle. More specifically, a preferred refueling method 400 in accordance with the present invention begins, at step 401, with the two-level arrangement of core 104, as indicated in FIG. 4. Reactor 100 is operated initially with all fresh fuel bundles, at step 402. Reactor 100 is shut down for refueling, as indicated in step 403. Some or all fuel bundles in upper matrix 126 are removed, at step 404, and placed in temporary storage. Fuel bundles in lower matrix 124 are removed, at step 405, from vessel 102 and processed for disposal. The temporarily removed fuel bundles from upper matrix 126 are inverted, at step 406, and installed in lower matrix 124, at step 407. Fresh fuel bundles are then installed, at step 408, plenum side up in upper matrix 126. Reactor 100 is then reactivated, reiterating method 400 beginning with step 402. Method 400 can be applied to one pair of fuel bundles or to many at a time. The invention provides for repositioning a fuel bundle from top upper matrix 126 to the corresponding position in lower matrix 124. Alternatively, the fuel bundle can be positioned within lower matrix 124 at a position other than the one under its original position in upper matrix 126. Method 400 is adapted to the axial spectral shift in neutron flux due to boiling in the core of a boiling-water reactor. In such a reactor, method 400 characterizes a desired net flow of fuel bundles. It does not preclude the movement of bundles within a level, or the movement of fuel bundles from the lower matrix to the upper matrix. In addition, it does not preclude introducing fresh fuel bundles into a lower matrix or retiring fuel bundles from an upper matrix. The same considerations that led to shifting fuel bundles in conventional reactors apply to reactors with bi-level cores. The present invention provides additional flexibility in redistributing fuel. The present invention provides for cores with two or more levels of fuel units, which can be monolithic or contain multiple elements. The bundles on a level can be packed as triangles, rectangles including squares, or hexagons. Other packing shapes are also provided for. Some embodiments employing control rods do not use them at all core levels. Power output regulation can be effected using burnable poisons, adjusting coolant flow and temperature, and/or using other power regulation approaches. Access to a lower core level can be through an upper core level, from the bottom, or through lateral access. The advance provided by the present invention in core design and refueling procedure is best understood in the context of parallel advances in reactor design and operation, as described below. In one embodiment, core or fuel baskets are used to arrange fuel bundles into an upper or lower arrangement (i.e., one basket would contain the top layer of fuel, and a second basket would contain the bottom layer). Each basket has the capability to be covered for transfer of all bundles in a single move, and the cover or lid allows the basket to be inverted in the storage pool in preparation for transfer of fuel. These core baskets also have the capability to contain poison curtains or fuel channels, as necessary, for various fuel arrangements. Baskets can be fully or partially pre-loaded prior to a refuel outage. The current state of the art in BWRs is split into two paths. The first path is that of the large forced-circulation boiling-water reactors (FCBWRs). The second path is represented by natural-circulation boiling-water reactors (NCBWRs). The recent FCBWR represents a major improvement over previously existing plants because of its improved economics, enhanced safety, low maintenance, and low personnel exposure. In addition, its use of advanced control and instrumentation simplify construction and operation. The FCBWR also offers reduced construction cost per kilowatt, as well as reduced radioactive waste. The NCBWR is designed to meet the objective of high simplicity and high inherent safety. It is also designed to meet a demand, by certain segments of the industry, for smaller plants. The present invention provides a third type of BWR, a steam-cooled reactor boiling-water reactor (SCBWR) with a two-stage core. A lower stage is a conventional boiling water reactor core which converts the subcooled inlet water to saturated steam. An upper stage is fed by the steam from the lower stage and converts it to superheated steam. The fuel bundle mechanical design for the two stages is identical, and the upper stage is loaded with fresh fuel while the lower stage is loaded with inverted fuel that has undergone one cycle of exposure in the upper stage. After operation in the lower stage, the fuel is discharged. The movement of fuel from the upper to the lower stage has several advantages. It initially maximizes the conversion ratio of U238 and Pu240 by resonance capture in the hard neutron spectrum, isotopically enhancing the fuel. Subsequently, it maximizes burnout of the Pu and high-level wastes in the thermal spectrum of the boiling stage, limiting conversion of U238 near the end of bundle life. Furthermore, maximum flexibility is provided for achieving power distribution shaping by means of enrichment and burnable poisons. With uranium fuel, a nuclear lifetime of 150,000 megawatt day per metric tonne (MWD/Tonne) is attainable. When plutonium fuel is used an exposure of 200,000 MWD/Tonne can be achieved. In either case, high conversion is achieved and significant reductions in the generation of high-level waste is realized by burning in the boiling stage. This offers some of the advantages of recycling without having to chemically reprocess fuel. Inherent safety is achieved by the incorporation of poison curtains. Poison curtains of boron material prevent an insertion of positive reactivity if the upper stage is flooded. The boron is essentially transparent to fast flux, but when the upper stage is flooded with water, the spectra becomes thermal and the boron becomes a strong poison. On the other hand, as the amount of superheat increases, the power also reduces due to neutron leakage and there is a strong negative power coefficient. Thus, if the operating point shifts too much to either side of the design point, the power is reduced automatically. Because of the inherent characteristics of the upper stage, only the lower stage needs control rods. Furthermore, channels or flow baffles are used only in the lower, boiling stage. This allows higher power density to be achieved without bumping into stability limits. Stability is also improved by the inversion of the fuel, since the fission gas plenum volume is in the subcooled single phase rather than the two-phase region. In the reactor core 500, shown in FIG. 5, fuel bundles 502 are configured hexagonally with Y-shaped upper stage poison curtains 504. The core length is approximately 3 meters (m) with only the lower half needing control rods, so the vessel length can be shortened relative to comparable FCBWR designs. With the use of a 7 m diameter vessel, an output of 1800 megawatts electric (MWe) is contemplated. This design is compatible with other passive safety features, such as a gravity-driven cooling system (GDCS). In one embodiment, each fuel bundle has a control rod or control element as part of the bundle or at least installed and removed with the bundle. This allows the use of large bundles without concern for safety during shipping and handling. The use of large bundles allows shorter refueling time and fewer control rod drives or control devices. Each hexagonal bundle 600 holds four hundred fuel rods 602 arranged on a triangular pitch as indicated in FIG. 6. The refueling interval can be three years. High enrichments on the order of 14% are used to achieve long fuel cycles and high power density. The use of burnable poisons allows the economical use of such enrichment without requiring the use of an excessive number of control elements or rods. Burnable posion will also be used to control power shape both axially and radially. The fuel is configured for efficient generation and burning of recycled plutonium. The bundle and core are designed so that the fuel is placed in a hard neutron spectrum (high steam void fraction) early in its exposure history and a soft neutron spectrum (low steam void fraction) late in its exposure history. This spectrum shift assists actinide burnup and plutonium production early in life and plutonium burnup late in life. One core implements a seed and blanket concept: the outer portion (blanket) of the core is tightly orificed to have a low void fraction and harder neutron spectrum; and the inner high power density portion (seed) where the flow is high and void fraction is low, yielding a softer neutron spectrum than the blanket. Another core uses a bundle designed so that it can be inverted in the middle of its life. One embodiment uses upgraded versions of conventional locking piston, while another embodiment uses upgraded conventional fine motion control rod drive systems. In another alternative embodiment, a fuel bundle 700 having a fixed hollow-walled control element 702 can be used, as shown in FIGS. 7 and 8. As an alternative to the H-shape of element 702, a cruciform shape can be used. In the case of a hexagonal bundle 600, a fixed control element 604 can have a Y shape. Alternatively, a hexagonal fuel bundle can employ a fixed hollow-wall control element with a star shape. Yet another option would be a matrix of tubes similar to a pin-type control element. In some embodiments, sufficient wall thickness is used to withstand full reactor pressure. In other embodiments, control elements comprise a series of tubes. In still further embodiments, control elements have reinforcing ribs. Another control blade configuration uses an array of pins. In the case of hollow-walled control elements, control is achieved by varying the level of a poison solution, such as sodium pentaborate, in the hollow member. Different embodiments provide different means for accomplishing poison solution level control. Preferably, the poison solution is displaced with gas to an external container which is at a pressure equal to the reactor pressure. The pressure in the member therefore is always above the reactor pressure which keeps the solution from boiling. Level in the member (which is analogous to control rod position in the present reactors) is measured either directly in the hollow member or indirectly by measuring the level in the container. Scram is achieved by dumping the differential pressure on loss of signal to the controller, causing all the solution to flow by gravity to the chamber, filling it to the top of active fuel. Alternative embodiments control the level of poison solution using a moveable suction tube hooked to a device similar to a traversing incore probe (TIP) positioner. Another alternative is to use an eductor which produces a variable suction pressure. The liquid system would be configured so that result of loss of the solution due to leakage would be no worse than a stuck rod in today's reactors. By virtue of the closed system with a high gas over-pressure, boiling does not occur even during a severe accident. For refueling, the chamber is filled up to the coupling and plugged so that there is permanent suppression of the reactivity of the bundle. One advantage of this device is that it maintains the bottom up reactivity control of the current plants which is preferred in the BWR but does so without bottom penetrations. A second advantage is that it does not require the motion of a control blade through a clearance which will make it even more immune to anticipated transient without scram (ATWS) than the present plants. In another alternative embodiment, control blades are positioned using a hydraulic control rod drive A900 shown in FIG. 9. In this concept, a movable control blade 902 is used. Control blade 902 is lifted by water flow past a piston 904 that is attached to the upper end of blade 902. The piston travels in a cylinder 906 which has progressively larger cross-section axial notches machined in its walls. Thus it takes increasingly larger flows to raise the blade higher. Alternatively, a piston can be in a constant cross-section tube and be compressing a spring which will also result in the effect of more flow further raising the blade. A third case would have a series of holes along the length of the tube that are progressively uncovered as the piston raises. In any case, stopping the pump will cause the rod to be inserted by gravity, thereby effecting scram. An alternative embodiment uses a turbine-driven control rod drive. Blades are moved by a lead screw, which can be a concentric double screw to reduce vertical height. The lead screw is driven by a water powered turbine which is driven by a source of clean deionized water. The lead screw engages the blade with a hydraulically latched collet that releases the blade, on loss of hydraulic pressure, causing it to drop by gravity for scram purposes. Redundant and diverse reactivity control is preserved using boron injection. Boron can be injected by gas from a high-pressure accumulator. Alternative embodiments inject boron by pressurizing a boron tank. The tank is pressurized by admitting steam from the reactor via an explosive valve. A gas eductor is used to produce the differential pressure to provide the required flow rate. Alternatively, a steam injector can be used to produce the differential pressure. The recirculation system for the preferred embodiment uses internal pumps. The preferred forced circulation system has pumps A02 mounted through a bioshield A04 on a vessel wall A06, and to an impeller case A08, as shown in FIG. 10. Pump A02 are at an elevation above the core A10 and below feedwater headers A12. Each pump discharge is connected to a duct A14 to the lower support. In the suction improvement feature, the feed water, rather than being sparged to the upper plenum, is directed to a low head eductor that raises the suction pressure enough to avoid cavitation. This feature also produces thorough mixing of the feed water and recirculation flow, thereby providing uniform core inlet enthalpy. The net positive suction head (NPSH) is expected to be adequate during periods of low feedwater flow because the pumps will be on low speed during that time. The side-mounted location of the pumps allows them to be of larger diameter than the under-vessel pumps of FCBWR and therefore they can be designed to have adequate inertia to avoid the need for motor-generator (MG) sets. In an alternative embodiment, pumps are driven by a long shaft from motors mounted on the bottle-necked top section of the vessel. This embodiment provides enhanced access for maintenance at the expense of having long shafts inside the RPV. Alternatively, a steam-driven jet pump can be used, requiring an auxiliary steam source but having no moving parts. Another embodiment uses a turbine-driven internal pump. A water-driven turbine is coupled to a centrifugal pump and provides the recirculation flow. The motive fluid for the turbine would be the feedwater. This device is more efficient than the feedwater-driven jet pump. High-pressure injection systems are used in some embodiments. The self-powered reactor core isolation cooling (RCIC) has the functional capability to provide indefinite makeup capability without external power input. In this concept, the RCIC turbine drives not only an injection pump but also a direct current (DC) generator which provide power to the system when in operation and also recharges the battery which provides the power to restart the system when it trips for any reason. Within reason, the generator can be sized to power other systems required during station blackout events. This is a non-safety system. Current containments suffer from the fact that they must be pressure retaining under accident conditions. This increases construction cost and raises public concern. It also leads to time consuming periodic leak rate testing. While any of the concepts can be used with standard containment concepts an advanced concept is proposed. In one embodiment, the containment is continuously vented during both normal and accident conditions through a filtration train that removes any fission products not removed by the suppression pool. The discharge of the filters is directed to the stack which provides a natural draft making it a passive device. The offgas recombiner gas discharge stream is ducted to the same stack. The filter train consists of a gravel bed which removes the particulate and provides a large surface area for plateout of other constituents. Synthetic zeolite can be used in place of the gravel. In another alternative filter design, a stainless-steel demister is maintained wet by a gravity feed of a solution such as sodium thiosulfate. While the normal heat load from the containment produces enough draft under most conditions, a temperature inversion might destroy the draft. Therefore, fans are used for normal operation. On loss of power, a gas torch is lit and maintains draft in the stack. For severe accident hydrogen control, battery powered ignitors are used. The power requirement for the ignitors is reduced by the use of a catalyst. In an embodiment with no bottom-mounted equipment on the RPV, the undervessel area is designed as a "core catcher" cooled by the suppression pool and made of a refractory material. Suppression pool cooling is by contact (i.e., dumping the pool on the corium) or heat transfer by having the pool water flow through the catcher. In either case, a thermally actuated valve initiates cooling. The catcher is designed to segregate the corium to a coolable geometry. The drywell is connected to the suppression pool by vents. The wetwell airspace is vented to the filter system and the path and filter system is designed to maintain the pressure atmospheric or below. All safety-related control and instrumentation (C&I) equipment is located in four bunkered vaults within the reactor building, corresponding to the four essential electrical divisions. These vaults provide an additional degree of protection against sabotage and fire. Each vault contains a remote shutdown panel for local control of the equipment in that division, and video communications equipment for coordinating the activities of operators in the other vaults or the main control room. Core-power monitoring is provided by a set of in-core detector assemblies which cover the full range from shutdown to full-power conditions. A gamma thermometer is employed as are fixed, in-core, calibration sensors. All monitoring and trip functions are based on local power rather than average power, thereby eliminating the need for an average power range monitor system. Core stability is ensured by protective reactor trip functions which are based on a combination of the magnitude and rate of change of local power measurements. In the preferred plant, communications/data acquisition systems process, sensor and transmitter data are provided to the local processing equipment over fiber optic links. Control output signals are similarly transmitted to the actuators. Communication between the local logic and control equipment and the main control room and process computer system uses wireless telemetry. Local multiplexing units (LMU), which contain radio frequency transmission circuitry, collect digitized data from the processing equipment and transmit the data to receiving units in the control building. These receiving units decode and process the data for use by the process computer system and the control room displays. The signals from the LMUs are transmitted at microwave frequencies, using repeater stations (or, in some cases, other LMUs) to route the signals to the control building receiving units. In an alternative embodiment, lower radio frequencies are used with direct broadcast techniques. This wireless communications system employs redundancy and diversity to assure high reliability. Physical and electrical independence and separation are readily maintained for safety-related signals. To prevent inter-divisional interference, different frequencies and various encoding techniques are used to assure independence of divisional signals. Alternatively, other wireless transmission methods, using infrared and laser devices, can be employed. A neural network-based plant safeguard system (PSS) monitors the overall plant safety status and takes action to mitigate disturbances. The PSS monitors all critical process measurements and, based on pattern recognition, sends commands to various plant systems (e.g., depressurization, recirculation flow control, feedwater control, rod control, etc.) to initiate actions to mitigate transient events. In addition, the PSS, coupled with a real-time, three-dimensional core power calculation, continuously monitors the margin between the "instantaneous" core status and the fuel thermal limits, and can initiate actions to prevent a violation of thermal limits. This system allows the operating limit minimum critical power ratio (OLMCPR) to be set very close to the safety limit critical power ratio (SLMCPR). Through the extensive application of plant-wide automation and knowledge-based operator support systems, a single operator can adequately perform all monitoring and control functions during normal and emergency conditions. All controls are voice actuated. The voice decoder receives the voice input and checks it against an audio spectrum corresponding to each qualified operator's voice, thereby limiting the voices to which the system will respond. An expert system based on the emergency operating procedures is provided to give the operator guidance on actions which should be taken, the priority of those actions, and the maximum time available to take each action. The operator can interrogate the system to obtain the bases for the recommended actions. Once the recommended actions are approved by the operator, the system will automatically perform the tasks. The main control room is completely non-Class 1E and is located in a non-safety grade structure. In the event of a loss of the non-Class 1 E control room, control of the plant is shifted to the remote shutdown panels located in the safety-related equipment vaults or to the off-site, emergency control room. The emergency control room and the technical support center are provided at an off-site location. Locating these facilities off-site minimizes the requirements for radiation protection and security measures during an emergency. In addition, the probability of a simultaneous loss of power at the plant and the emergency control room is small. Microwave communications transmit data between these facilities and the plant. Diagnostic and maintenance activities on C&I equipment are performed using portable technician interface units. Operations and maintenance (O&M) procedures and historical records of maintenance activities are stored on compact disks which are located in the local panels and racks. The compact disks also store the calibration data so that the technician interface unit can automatically calibrate each replacement module before placing it in service. Spare parts management is achieved by tracking bar codes on each replaceable module using a scanner on the technician interface unit. Maintenance instructions and equipment tagging are to be performed by a maintenance computer which is linked to the plant communications system. Upon approval from maintenance and operations personnel, the system identifies a piece of equipment as "tagged out" for maintenance by posting a notice on a digital display located on a wall near the equipment. The system also modifies the control room displays and controls associated with that equipment, and tracks the procedure through on-line communications with the technician interface unit. The operating and maintenance staff can also interrogate the maintenance computer before issuing a tagging command to ensure that the action will not violate technical specifications. A neural network is used to predict the time to equipment failures, based on records of equipment maintenance, operating environments, and performance trends. An expert system is provided to allow flexible surveillance periods and reduced surveillance requirements for each plant system based upon a record of actual plant operating conditions (e.g., availability, capacity factor, maintenance history, etc.). As the performance of an individual system or component improves, the surveillance and maintenance schedules are automatically revised. In addition to reducing the burden on the maintenance staff, these systems improve the reliability of plant systems by assuring timely surveillance and replacement of critical components. All surveillance, testing and diagnostics activities are fully automated. The essential, on-site power source is provided by four divisions of high energy-density, nickel-cadmium batteries. The present invention provides for the production of superheat by combining a conventional light water reactor (LWR), such as a BWR, with a liquid metal-cooled reactor (LMR). The two reactors are arranged in a process-system series configuration in which the LWR is used in conventional fashion to convert subcooled water into steam. LMR adds superheat to the steam. Superheated steam is conveyed to a superheat turbine-generator (T-G) for producing electricity. The condensate produced at the end of the thermodynamic process cycle is returned to the LWR as feedwater to be endlessly recycled. This combined cycle BWR/LMR has several advantages over a comparable reactor complex in which a BWR and an LMR are operated independently. A major advantage is an improved heat rate, i.e., a higher net reactor output results from a given level of heat generated at the core. This improved heat rate is mainly due to superheat added by the LMR. Further contributions to the heat rate are provided by significantly reduced auxiliary power loads, improved turbine stage efficiency, improved regenerative cycle thermodynamic efficiency, and incremental improvements gained by virtue of larger T-G machine sizes. Another advantage of the hybrid BWR/LMR is an improved fuel cycle as a result of net breeding which provides about 38% of required fissile input to the BWR and 100% for the LMR. A related advantage is the elimination of long-life waste streams by recycling actinides. Furthermore, the hybrid reactor yields reduced costs per kilowatt electric since the entire turbine island and balance of plant is eliminated from the LMR. Moreover, separator/reheaters can be eliminated in the BWR. The site footprint per megawatt electric generated can be reduced since a separate LMR turbine building is not required. Furthermore, dual use becomes possible for various other balance-of-plant buildings. In a like manner, shared use of nuclear island equipment and support facilities results in reductions in plant size and complexity. Reductions in operation and maintenance, including site security forces, are also achieved. This hybrid reactor presents significant safety improvements. For example, in a conventional LMR, heat must be transferred from the liquid metal coolant, typically, liquid sodium, to a secondary fluid, typically a water-steam mixture. The present hybrid reactor transfers the heat from the liquid metal to a single vapor phase, i.e., to steam only. The single phase destination permits a simpler heat exchanger design. In addition, the consequences of a heat exchanger breach are much less severe since it is steam rather than liquid water that would mix with the liquid sodium. These and other modifications to and variations upon the described embodiments are provided for by the present invention, the scope of which is limited only by the following claims.
050826026	claims	1. A process for regenerating a spent organic solvent containing anions and cations by separating and removing the anions and cations from the organic solvent, the process comprising: forming one or more alkaline aqueous solution phases for capturing anions via a first hydrophobic porous membrane and forming one or more acidic aqueous solution phases for capturing cations via a second hydrophobic porous membrane in the organic solvent containing cations and anions; capturing the cations by the acidic aqueous solution phases and the anions by the alkaline aqueous solution phases simultaneously through the first and second hydrophobic porous membranes; and collecting the acidic aqueous solution phases for removing the cations and collecting the alkaline aqueous solution phases for removing the anions. providing the first and second hydrophobic porous membranes in a regenerating device; passing the alkaline aqueous solution phases through the first hydrophobic porous membrane; passing the acidic aqueous solution phases through the second hydrophobic porous membrane; passing the spent organic solvent through the regenerating device so as to flow outside the first and second hydrophobic porous membranes; and further wherein the steps of passing the alkaline aqueous solution phases, the acidic aqueous solution phases and the spent organic solvent take place simultaneously. 2. A process according to claim 1, wherein the first and second hydrophobic porous membranes are made from a synthetic resin. 3. A process according to claim 2, wherein the first and second hydrophobic porous membranes are hollow fibers made from a synthetic resin. 4. A process according to claim 1, wherein the alkaline aqueous solution is passed through a first part of a bundle of hollow fibers made from a synthetic resin and the acidic aqueous solution is passed through a remainder of the bundle of hollow fibers and the bundle of hollow fibers is placed in a stream of the spent organic solvent. 5. A process according to claim 4, wherein the alkaline aqueous solution is an aqueous solution of sodium hydroxide, potassium hydroxide, hydrazine, hydroxylamine, ethanolamine or a mixture thereof, and the acidic aqueous solution is an aqueous solution of carbonic acid, formic acid, oxalic acid, butyric acid, tartaric acid or a mixture thereof. 6. A process according to claim 4, wherein the bundle of hollow fibers are constructed so as to place a string of hollow fiber passing the alkaline aqueous solution therethrough neighboring to at least one string of hollow fiber passing the acidic aqueous solution therethrough. 7. A process according to claim 1, wherein said first and second hydrophobic porous membranes are arranged in a regeneration column so as to be in close proximity to each other, a stream of the spent organic solvent is introduced into the column and the stream is caused to contact said first and second hydrophobic membranes simultaneously. 8. A process according to claim 1, further comprising regenerating the collected acidic aqueous solution phases for removing the cations and regenerating the collected alkaline aqueous solution phases for removing the anions. 9. A process according to claim 8, wherein the regeneration of the acidic aqueous solution phases for removing the cations takes place by ion exchange. 10. A process according to claim 8, wherein the regeneration of the alkaline aqueous solution phases for removing the anions takes place by distillation. 11. A process according to claim 1, wherein more than 98% of dibutyl phosphate which is present in the spent organic solvent is removed. 12. A process according to claim 1, wherein more than 95% of metal ions which are present in the spent organic solvent are removed. 13. A process according to claim 1, wherein capturing the cations by the acidic aqueous solution phases and the anions by the alkaline aqueous solution phases simultaneously includes: 14. A process according to claim 13, wherein the first hydrophobic membrane is made up of a first plurality of hollow fibers and the second hydrophobic membrane is made up of a second plurality of hollow fibers. 15. A process according to claim 14, wherein the first and second pluralities of hollow fibers are arranged in a bundle such that individual hollow fibers of the first plurality of hollow fibers are dispersed in the second plurality of hollow fibers. 16. A process according to claim 14, wherein the first and second pluralities of hollow fibers are arranged in a bundle such that individual hollow fibers of the first plurality of hollow fibers are alternatively disposed in relation to individual hollow fibers of the second plurality of hollow fibers. 17. A process according to claim 13, wherein said first and second hydrophobic porous membranes are arranged in a regeneration column so as to be in close proximity to each other, a stream of the spent organic solvent is introduced into the column and the stream is caused to contact said first and second hydrophobic membranes simultaneously.
048225525	claims	1. A method for passively scanning the gamma radiation emission count of nuclear fuel contained within a fuel rod to determine enrichment uniformity comprising the steps of: (a) advancing a fuel rod along a linear path of travel; (b) repeatedly detecting the natural gamma radiation emission count of the advancing rod at each of a plurality of regularly spaced apart discrete segments along the length of the advancing rod; and (c) summing the output of each of the detecting steps for each segment to obtain a total gamma radiation emission count for each segment. (a) means for advancing a fuel rod along a linear path of travel; (b) means positioned along the path of travel for repeatedly detecting the natural gamma radiation emission count at each of a plurality of regularly spaced apart discrete segments along the length of said fuel rod as said fuel rod advances along said linear path of travel; and (c) means for summing the gamma radiation count for each segment to obtain a total gamma radiation emission count for each segment. a feed table positioned adjacent said rod advancing means, with said feed table being adapted to a plurality of rods in a side-by-side arrangement; means for individually transferring the rods from said feed table onto said rod advancing means. an unloading table positioned adjacent said rod advancing means, with said detecting means being positioned between said feed table and said unloading table, and means for individually transferring the rods from said rod advancing means onto said unloading table. a plurality of detectors, with each of said detectors comprising (a) a housing including a hole for admitting a nuclear fuel rod therethrough, (b) means mounted in said housing for detecting gamma radiation of a predetermined energy level in a fuel rod extending through said hole, means mounting said detectors in a linear side-by-side arrangement and with said holes being linearly aligned so as to permit a fuel rod to be advanced through the aligned hole, and control means operatively connected to each of said detectors for recording the count of the detectors in shifted time intervals corresponding to the passage of a given segment of a fuel rod being continuously advanced through said holes of said detectors, and for adding the counts for each such segment of said fuel rod. 2. A method as claimed in claim 1 including the step of calculating from the total gamma radiation emission count for each segment the enrichment value for each segment and the average enrichment value for said fuel rod. 3. A method as claimed in claim 2 including the step of monitoring the average enrichment value of the fuel rod for deviations from a specified enrichment value, and/or for deviations in the enrichment values of adjacent segments of said fuel rod greater than a predetermined percentage. 4. An apparatus for passively scanning the gamma radiation emission count of nuclear fuel contained within a nuclear fuel rod to determine enrichment uniformity comprising: 5. The apparatus as claimed in claim 4 including calculating means for determining the enrichment value for each of said segments from the total count for each segment and the average enrichment value for said fuel rod. 6. The apparatus as set forth in claim 4 wherein said means for repeatedly detecting the gamma radiation emission count of the advancing fuel rod includes a plurality of linearly aligned detectors, with each of said detectors including means for detecting gamma radiation of a predetermined energy level. 7. The apparatus as set forth in claim 6 wherein each detector has a hole extending through said detector for receiving and encompassing the periphery of said fuel rod and including tubular sleeve segment means positioned within each detector hole for defining an annular window within each detector hole for collimating the gamma radiation from said fuel rod to each detector. 8. The apparatus as set forth in claim 6 including means enclosing said detectors for shielding said detectors from outside radiation sources. 9. The apparatus as defined in claim 4 further comprising 10. The apparatus as defined in claim 9 further comprising 11. An apparatus for passively scanning the gamma radiation emission count of nuclear fuel contained in a nuclear fuel rod to determine enrichment uniformity, and comprising 12. The apparatus as defined in claim 11 wherein said collimating means of each of said detectors comprises a pair of spaced apart sleeve segments positioned coaxially in the associated hole, and with said sleeve segments being composed of a material adapted to block the passage of gamma radiation, and with said sleeve segments being linearly spaced apart to define a narrow window for the passage of gamma radiation to said detecting means.
059404647	description	FIGS. 1 and 2 indicate that there is no significant enhancement of the resistance to corrosion in lithium containing water beyond about 0.6% Sn and 0.2% Fe. FIGS. 3 and 4 show there is an interest in an iron content higher than 0.2%, for enhancing the resistance to corrosion in water steam at 400.degree. C. and 415.degree. C. and reducing the undesirable effect of a high Sn content. Such Figures also indicate that the favorable results which are found for an alloy according to the invention are lost if there is a low tin content or no tin. Last, FIG. 5 indicates that there is a progressive loss of the resistance to nodular corrosion when the tin content increases, without significant improvement of the characteristics by adding iron. FIG. 5 shows that beyond a tin content of 0.6%, corrosion became faster and it also shows that, for an acceptable tin content, corrosion is faster if the iron content increases beyond about 0.3%. From a general consideration of all results, a composition range which is favorable regarding corrosion is defined by the three curves indicated in FIG. 6. Curve A limits a zone of interest as regards resistance in water at 360.degree. C. with a 70 ppm lithium content i.e. under conditions which are more severe than those which prevail in a reactor, as regards the lithium content. Curve B limits a zone in which there is satisfactory resistance in lithium containing steam at a temperature slightly beyond 400.degree. C. Last, curve C approximately corresponds to a limit of the acceptable contents as regards nodular corrosion resistance, in water steam at 500.degree. C. It is however possible to exceed the above indicated zone when some types of corrosion are not likely to occur.
	claims	1. A beam splitting apparatus for use within a lithographic system, comprising:a plurality of static mirrors each configured to receive a different part of a first radiation beam from a radiation source and reflect a respective portion of radiation along one of a plurality of directions to form a plurality of branch radiation beams for provision to two or more lithographic apparatuses,wherein each lithographic apparatus is configured to receive a respective one of the plurality of branch radiation beams, direct the respective branch radiation beam onto a patterning device, and project a respective patterned beam onto a substrate,wherein each lithographic apparatus is associated with a respective patterning device and a respective substrate such that patterning of plural substrates can be performed by the two or more lithographic apparatuses in parallel,wherein the radiation source comprises a first free electron laser and a second free electron laser, andwherein the first radiation beam is a composite radiation beam comprising radiation from at least one of the first and second free electron lasers. 2. The beam splitting apparatus of claim 1, wherein each of the plurality of directions provides a respective branch optical path, each branch optical path being associated with a respective one of the lithographic apparatuses. 3. The beam splitting apparatus of claim 2, wherein at least one branch optical path is associated with two or more of the plurality of the static mirrors such that at least one of the plurality of branch radiation beams comprises a plurality of said reflected portions of radiation. 4. The beam splitting apparatus of claim 2, wherein each of the branch optical paths is associated with a respective plurality of the static mirrors such that each branch radiation beam comprises a plurality of said reflected portions. 5. The beam splitting apparatus of claim 1, wherein each static mirror is arranged to extend partially across a path of the first radiation beam. 6. The beam splitting apparatus claim 1, wherein at least some of the plurality of static mirrors are configured to reflect a solid area of the first radiation beam. 7. The beam splitting apparatus of claim 2, wherein at least two or more of the plurality of static mirrors comprise a reflective grating, wherein the reflective grating comprises a plurality of faces. 8. The beam splitting apparatus of claim 7, wherein each face of the reflective grating that is associated with a same one of the plurality of directions extends substantially parallel to a single silicon crystal plane of the reflective grating. 9. The beam splitting apparatus of claim 7, wherein the reflective grating is a macro-scale grating. 10. The beam splitting apparatus of claim 9, wherein the faces are arranged such that expansion of each reflected portion causes partial overlap of at least two reflected portions associated with one branch optical path at the one of the lithographic apparatuses associated with that one branch optical path. 11. The beam splitting apparatus of claim 10, wherein the faces are arranged such that the overlapping reflected portions provide a branch radiation beam having an intensity profile substantially the same as an intensity profile of the first radiation beam. 12. The beam splitting apparatus of claim 7, wherein the reflective grating comprises a first plurality of faces associated with a first branch optical path to provide a first branch radiation beam;wherein each one of the first plurality of faces is arranged to reflect a respective part of the first radiation beam to form a respective sub-beam of the first branch radiation beam; andwherein the first plurality of faces is arranged such that if a position of the first radiation beam changes in a plane perpendicular to a propagation direction of the first radiation beam, a power received by at least one of the first plurality of faces increases and a power received by at least one of the first plurality of faces decreases. 13. The beam splitting apparatus of claim 7, wherein the reflective grating is a micro-scale grating. 14. The beam splitting apparatus of claim 13, wherein the faces of the reflective grating are arranged such that portions of radiation reflected from the grating diffract to provide said plurality of branch radiation beams. 15. The beam splitting apparatus of claim 14, wherein the faces of the reflective grating are arranged such that each branch radiation beam has an intensity profile substantially similar to an intensity profile of the first radiation beam. 16. The beam splitting apparatus of claim 7, wherein the faces of the reflective grating have translational symmetry in at least one direction perpendicular to a direction of propagation of the first radiation beam. 17. The beam splitting apparatus of claim 7, wherein the beam splitting apparatus comprises expansion and/or flat-top forming optics, and wherein the reflective grating is disposed upstream of said expansion and/or flat-top forming optics. 18. The beam splitting apparatus of claim 7, wherein the reflective grating is arranged to receive the radiation beam from a flat mirror disposed between the radiation source and the reflective grating. 19. The beam splitting apparatus of claim 7, wherein the reflective grating is formed from etched silicon. 20. The beam splitting apparatus of claim 19, wherein the reflective grating comprises a reflective coating, the reflective coating comprising a material or composition selected for grazing incidence reflectivity of a desired wavelength. 21. The beam splitting apparatus of claim 7, further comprising a second reflective grating arranged to further split at least one of the branch radiation beams provided by the reflective grating. 22. The beam splitting apparatus of claim 1, wherein at least one of the static mirrors is provided with one or more apertures arranged to permit a portion of the first radiation beam not reflected by the at least one static mirror through the aperture towards a further one of the plurality of static mirrors. 23. The beam splitting apparatus of claim 1, wherein at least one of said static mirrors comprises a ring-shaped reflective surface arranged to reflect a portion of radiation along an associated branch optical path and to permit a portion of the first radiation beam through an aperture defined by the ring toward a further one of the plurality of static mirrors. 24. The beam splitting apparatus of claim 23, wherein said ring-shaped reflective surface is arranged such that if a position of the first radiation beam changes in a plane perpendicular to a propagation direction of the first radiation beam, a power received by at least one part of the ring-based reflective surface increases and a power received by at least a further part of the ring-based reflective surface decreases. 25. The beam splitting apparatus of claim 1, wherein at least one of the static mirrors comprises a first reflective surface and a second reflective surface joined along an edge, wherein the edge is arranged for placement within a radiation beam. 26. The beam splitting apparatus of claim 1, wherein at least one of the static mirrors is provided with active cooling. 27. The beam splitting apparatus of claim 1, further comprising: at least one diverging optical element arranged to increase the divergence of a radiation beam. 28. The beam splitting apparatus of claim 27, further comprising: a plurality of diverging optical elements, each arranged to increase the divergence of a respective one of the branch radiation beams. 29. A system comprising:a radiation source configured to produce a main radiation beam, the radiation source comprising:a first free electron laser; anda second free electron laser;a plurality of optical elements configured to:receive at least one of a first radiation beam from the first free electron laser and a second radiation beam from the second free electron laser; andoutput the main radiation beam;a beam splitting apparatus configured to split the main radiation beam into a plurality of branch radiation beams, comprising:a plurality of static mirrors each configured to:receive a different part of the main radiation beam; andreflect a respective portion of radiation along one of a plurality of directions to form the branch radiation beams; andtwo or more lithographic apparatuses, wherein each lithographic apparatus is configured to receive a respective one of the plurality of branch radiation beams, direct the respective branch radiation beam onto a patterning device, and project a respective patterned beam onto a substrate,wherein each lithographic apparatus is associated with a respective patterning device and a respective substrate such that patterning of plural substrates can be performed by the two or more lithographic apparatuses in parallel. 30. The system of claim 29, further comprising: a respective diverging optical element for each of the lithographic apparatuses. 31. The system of claim 30, wherein the beam splitting apparatus is configured such that at least two or more of the plurality of static mirrors comprise a reflective grating comprising a plurality of faces, and wherein each respective diverging optical element is downstream of the reflective grating. 32. The system of claim 30, wherein the diverging optical element comprises a convex, concave, and/or saddle shaped grazing incidence mirror. 33. The system of claim 29, further comprising: optics configured to modify a cross-sectional shape of a branch radiation beam. 34. The system of claim 33, wherein the optics comprise an array of mirrors arranged to split the branch radiation beam into a plurality of sub-beams and to combine the sub-beams together. 35. The system of claim 29, wherein the main radiation beam comprises EUV radiation. 36. The system of claim 29, further comprising: a mask inspection apparatus arranged to receive one of the branch radiation beams from the beam splitting apparatus. 37. A method comprising:producing a main radiation beam using a radiation source wherein the radiation source comprises a first free electron laser and a second free electron laser, wherein the main radiation beam is a composite radiation beam comprising radiation from at least one of the first and second free electron lasers; anddirecting the main radiation beam to a beam splitting apparatus,wherein the beam splitting apparatus comprises a plurality of static mirrors each arranged to receive a different part of the main radiation beam and reflect a respective portion of radiation along one of a plurality of directions to form a plurality of branch radiation beams for provision to a first lithographic apparatus and a second lithographic apparatus,wherein the first and second lithographic apparatuses are each configured to receive a respective one of the plurality of branch radiation beams, direct the respective branch radiation beam onto a patterning device, and project a respective patterned branch onto a substrate, andwherein each lithographic apparatus is associated with a respective patterning device and a respective substrate such that patterning of plural substrates can be performed by the two or more lithographic apparatuses in parallel. 38. The method of claim 37, further comprising: directing each branch radiation beam to a respective lithographic apparatus.

Subsets and Splits

No community queries yet

The top public SQL queries from the community will appear here once available.