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054835623	description	DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1a-c show a volume delimitation tank 1 according to the invention immersed into a fuel pool or a reactor pool 2. The shown tank 1 is intended to be used for scrapping control rods 3. In FIGS. 1a-c, the numeral 4 designates the protective concrete around the fuel or reactor pools 2 in the reactor building. The tank 1 is arranged suspended in the pool 2 and is attached to the edge 5 of the pool in a beam structure 6. The tank 1 substantially comprises vertical walls 1a-d shaped to form a channel and a box-shaped bottom part 9 for capturing debris. The tank 1 may, for example, have a height of 10 meters and the bottom part 9 may, for example, have an area of 5.times.3 meters. Inside the tank 1 there is a frame structure 10 for suspension of tools, such as a first spark machining device 11 and a gas hood 12. The frame structure 10 is also provided with two platforms 13 for the arrangement of tools such as a second spark machining device 14, a plugging device 15 and with machining positions for the objects which are to be machined. At the bottom of the tank 1, a cleaning device 16 is arranged, with an inlet conduit 17 and an outlet conduit 18 for continuously cleaning the contained volume. When scrapping control rods 3, the volume delimitation tank 1 is used, for example, in a work cycle as follows: 1. Divisible support rods 19 intended to support at least the vertical walls 1a-d of the tank 1 are mounted. The walls 1a-d formed of a channel are arranged at the bottom part 9, whereafter the support rods 19 are arranged at the walls 1a-d. The size of the tank 1 is chosen according to the size of the object to be machined or according to other needs, such as the size of the machining equipment. As clearly shown in FIGS. 2a and 3a, the tank has an open top through which, as seen in FIGS. 1a and 1b, control rods 3 can be inserted and can be clearly viewed from above, when carrying out the invention. 2. The volume delimitation tank 1 with the support rods 19 and the bottom part 9 are lowered into the pool 2, whereby the tank 1 is filled with water from the pool. The vertical walls 1a-d of the tank 1 unfold or form folds. The tank 1 is arranged at the beam structure 6 with substantially horizontal beams 7 projecting over the pool 2. 3. The divisible frame structure 10 is mounted and provided with two platforms 13 for tools. The frame structure 10 is lowered into the tank 1 and arranged at the beams 6 on the pool edge 5. The tank 1 may be attached to the frame structure 10 instead of being attached to the beams 6, or both to the beams 6 and to the frame structure 10. 4. The remotely operated tools which are used for the machining are lowered down into the tank 1 and arranged at a suitable location at the frame structure 10. A scrap stand 20 for scrapped control rods 3 is arranged at the frame structure 10. 5. The control rod/rods to be scrapped is/are moved into the tank and arranged in a machining position or in a waiting position 21. 6. The scrapping operation is started whereby control rods 3 are transferred one at a time, by means of a remotely operated gripping tool (not shown), to a first machining position, a cutting position 22 where the shafts 23 of the control rods are cut off by means of the second spark machining device 14. Gases which may then leak out from the control rod 3, such as tritium and/or deuterium, are evacuated continuously via the openable gas hood 12. The shaft 23 is brought to the scrap stand 20, whereafter the hole left in the control rod 3 by the shaft 23, by means of the plugging device 15 in a second machining position 24, is plugged up to prevent further gas leakage. After the plugging, the control rod 3 is brought to a third machining position 25 where two opposed control rod blades of the cruciform control rod 3 are dismantled by means of the first spark machining device 11, whereafter they are arranged together with the non-dismantled control rod blades in the scrap stand 20. The work in the separate positions 22, 24, 25 can take place in parallel. The water is cleaned continuously during the entire work cycle by means of the cleaning device 16, which admits water via the inlet conduit 17 from the lower part of the tank, as well as at the spark gaps, that is, at the first and the second spark machining device 11, 14 (not shown), and cleans this water whereafter the water is returned to the tank 1 by way of the outlet conduit 18. The advantage of continuous cleaning is that the activity level in the water is kept low while at the same time the time for cleaning the total volume after completed work is considerably reduced. 7. After completed work, the entire contained volume is cleaned. In those cases where cutting methods have been used, the bottom part 9 is possibly slurry-exhausted to capture chips. Then the tank 1 is opened wholly or partially to insert new control rods 3 or other objects. When the scrap stand 20 is full, it is lifted, possibly after flushing, out of the tank 1 and is arranged in a transport flask (not shown) for transport to a storage for ultimate radiactive waste disposal. 8. When no more objects are to be machined, all loose parts, such as tools, are flushed clean and are then lifted out of the tank 1, and then the tank 1 is dismantled. The frame structure 10 is flushed clean and is dismantled as it is being lifted up, the walls 1a-d are also flushed clean as they are being lifted up. The bottom part 9 is slurry-exhausted if necessary. Any final cleaning is carried out in the reactor hall 26 associated with the fuel or reactor pool 2, and the parts are packed for storage or transport. The FIGS. 2-8 of the drawings described in the following show examples of different embodiments of the tank 1 and how this is open or openable for moving objects into/out of the surrounding pool 2. FIG. 2a shows a volume delimitation tank 1 of a woven material which, in order to obtain a well-defined folding of at least the vertical walls 1a-d of the tank, is provided at the manufacturing stage with fold notches 27 at specified intervals. The fold notches 27 can be achieved by weaving in a coarser thread at the notches 27 during manufacture. The tank 1 is formed as a sack with an integrated, possibly stiff square bottom part 9 and with four wall sections 1a-d. Each wall section 1a-d is cut and joined together to the next one such that the walls 1a-d, when being lowered, are folded in a well-defined and predetermined way. From FIG. 2b it is clear that the folding takes place such that every other folded section in a horizontal cross section A--A in one fold increased in the longitudinal direction 1 whereas every other folded section in a horizontal cross section B--B in an adjacent fold increases in the transverse direction t. To control the raising and lowering of the walls 1a-d, loops 29 are provided which run around the support rods 19 which distend the tank 1 at its corner portions. Ropes 30 are connected to at least the uppermost loops 29a to raise the lower the walls 1a-d. The ropes 30 run along the support rods 19 to the beam structure 6 and then along this beam structure to a pulley 30a. The tank in the figure is not entirely distended. The tank 1 is suspended from the beam structure 6 which rests on the edge 5 of the pool. Loops 29 and ropes 30 are preferably made of the same fibres as the walls 1a-d of the tank 1. FIG. 3a shows a tank 1 with walls 1a-d which, as in FIG. 2, are provided with woven-in fold notches 27. In the same way as the tank 1 shown in FIG. 2, this tank 1 is provided with support rods 19 and loops 29 at the corner portions to control the raising and lowering of the walls 1a-d. In the same way as in FIG. 2, ropes 30 are arranged at at least the upper loop 29a in each corner portion for raising and lowering. From FIG. 3b it is clear that when the walls 1a-d are to be lowered, the folding takes place such that every other folded section in a horizontal cross section C--C in one fold is given a larger cross-section area than a horizontal cross section D--D in an adjacent fold. The tank 1 is suspended from the beam structure 6, which rests on the pools' edge 5. FIGS. 4a and 4b show a volume delimitation tank 1 in which at least one wall section 1b is separately raisable and lowerable. This is advantageous for repeated use, whereby not all walls 1a-d need be lowered to move objects in and out, respectively. Depending on the nature of the contamination, point exhaustion can be used during the machining; alternatively, chips can be sucked up from the bottom part 9 after completed work, and it is then not necessary that the whole volume of water be cleaned before lowering the wall portion and moving objects in/out. The non-separately raisable and lowerable walls 1a, 1c and 1d may be made of cloth, fabric or plate, by plate being meant two or more layers of laminate of cloth or fabric, of a suitable fibre. When the walls 1a, 1c, 1d are made of cloth or fabric, support rods 19 are arranged at at least the corners of the tank 1, and preferably also at the upper part thereof. When such a tank 1 is dismantled, the walls 1a, 1c, 1d are allowed to buckle arbitrarily. When the walls 1a, 1c, 1d are made of a stiff plate, they may be provided with fold notches 27, as is clear from FIG. 5, such that the walls can be folded into a suitable size. The separately raisable and lowerable section 1b can either be made of fabric with woven-in fold notches 27, as shown in FIG. 4a, or of fabric or cloth which is rolled off and onto a shaft 28 which may be arranged horizontally or vertically (not shown in the figure). The ropes 30 are adapted to raise and lower the wall section 1b. The ropes 30 run via pulleys 30b to the pulley 30a. One end of the shaft 28 may be provided with a motor (not shown) for rolling on and off. The section 1b runs along the vertical support rods 19a. When the section 1b is arranged in raised position, the tank 1 is sufficiently tight to the surrounding medium. If additional tightness to the surrounding medium is desired, sub-atmospheric pressure of sufficient magnitude is arranged in the tank for the separately raisable and lowerable wall section 1b to fit tightly against the support rod 19a, any leakage being directed inwards towards the contaminated volume. FIGS. 6a and 6b show an embodiment with a sluice 31. The use of a sluice 31 is especially advantageous with repeated use of the tank 1 since the sluice 31 only requires cleaning of a small volume of water when moving objects in and out. The walls 1a-d and the sluice 31 are made of cloth, of fabric, or of a plate. In FIG. 6a, an object is sluiced out by opening the inner sluice-gate 32a, towards the sluice 31, the sluice-gate 32a being preferably made of a stiff plate where the opening takes place by remote operation from the work platform 7. Objects are introduced into the sluice 31 and the inner gate 32a is shut. The water in the slucie 31 is cleaned by means of the cleaning equipment 16 arranged in the tank 1 and the object is possibly flushed before the outer sluice gate 32b is opened towards the pool 2 to pass out the object thereto. If additional tightness to the surrounding medium is desired, sub-atmospheric pressure of sufficient magnitude is arranged in the sluice 31 for the sluice-gates 32a-b to fit tightly. FIG. 6b shows sluice-gates 32a-b made of cloth or fabric, expanded by means of an upper and a lower support rod 19b which, in turned-up position, are substantially horizontal and parallel and which are interconnected, at least at the openable long side, via a substantially vertical support rod 19c. When opening the sluice-gate 32a-b, the support rods 19b are turned down (or up) in the vertical direction by means of a turning device 33 which is remote-controlled from the work platform 7, the cloth surface or fabric surface of the sluice-gate thus being allowed to buckle arbitrarily. As with the sluice design shown in FIG. 6a, sub-atmospheric pressure can be arranged in the tank 1, if additional tightness against the surrounding medium is desired. A suitable way is to ensure that the water level in the tank 1 is lower than in the sluice 31 and that the water level in the pool 2 is higher than in the sluice 31. An additional cleaning device 16 can possibly be arranged in the sluice 31 for continuous cleaning of this volume. The advantage of the design in FIG. 6b is that the sluice takes up little space since the sluice-gates 32a-b are turned downwards (upwards) instead of outwards/inwards. The sluice 31 can be detachably arranged at the tank 1 such that exchange of sluices 31 of different sizes can be made in a simple manner. FIG. 7 shows a tank 1 with five wall sections 1a-e, two of the wall sections 1b and 1e being arranged at least partially to overlap, thus forming a flow passage where a small exchange of water between the water in the tank 1 and the water in the pool 2 is allowed. In those cases where cleaned water is continuously pumped out of the tank 1, such that sub-atmospheric pressure prevails, water will only flow into the tank via the passage, that is, contaminated water does not flow out into the pool 2 via the passage. This tank 1, as the one described in FIGS. 2-6, can be made of cloth, of fabric, or as a plate. In the cloth or fabric design, the walls 1a-e are allowed to buckle arbitrarily when the tank is dismantled. In those cases where the tank 1 is made as a plate, it is provided with fold notches 27, according to FIG. 5, such that the plate can be folded in suitably large sections. The tank 1 according to this embodiment can also be provided with hinges 34, allowing the inner wall section 1e to be turned out and fit tightly against the outer wall section 1b. FIG. 8 shows a tank 1 made with an oval cross section. The tank 1 can also be made with a circular cross section. In both cases it can be designed with or without fold notch 27. The tank 1 is provided with support rods 19, around the vertical support rods 19 there being arranged loops 29, 29a for control of the raising and lowering of the wall 1a. The concept fabric according to the above comprises the traditional way of manufacturing textile fabrics, where a two-thread system with crossing threads, warp and weft is used, but also manufacture by means of, for example, tricot technique or knitting with a single-thread system where a thread forms meshes with itself or with parallel-running threads, or manufacture by means of so-called nonwoven technique where the material is neither woven nor knitted but where loose fibres are bound together in the form of a pile with the aid of glue or chemicals.
	description	The present invention relates to a device and method for cleaning surfaces within the nuclear industry and in particular surfaces that are placed in liquid in a nuclear power plant or repository for spent nuclear fuel. In a nuclear plant, the reactor and fuel storage pools contain pure water and the overall environment in the pools are to be kept as clean as possible. However, when for example the reactor is in use, a certain amount of radioactive debris and particles, such as crud from the fuel rods or metal chips from wear on reactor components, circulate in the pool and water system and will deposit on surfaces such as floor surfaces and wall surfaces of pools and pipes. These surfaces need to be cleaned at certain predetermined intervals in order to maintain a high level of cleanliness. The normal procedure is to empty the water from the pools and to clean the surfaces manually with mechanical cleaning devices such as brushes or sponges as well as with high pressure water. Certain objections have been raised regarding these cleaning methods because they are time consuming and expose workers to radiation. It is also important to clean these surfaces as much as possible since aerosols are liberated when lowering the water level. This may adversely affect persons in this environment and demands have been made to reduce the exposure due to contaminants introduced into in the environment by aerosol. A number of devices have been developed that may perform cleaning of surfaces with reduced labour and also without the need to empty the pools. However, these types of devices are specifically designed to move around on the floor and cannot be used on vertical surfaces. Other types of cleaning devices are designed for cleaning vertical walls, but do require additional equipment in order to be able to move around, such as lifting devices. In general the devices developed are not suited for nuclear environments, i.e. chemical, mechanical and electrical requirements on equipment and material to be used in the nuclear environment. Thus there are still improvements to be made in this area. The aim of the present invention is to remedy the drawbacks of the state of the art and to provide a cleaning device that is adapted to the specific environment where it is to be used and is versatile enough to handle both horizontal and vertical surfaces to be cleaned. There is disclosed herein a device for submersible cleaning of surfaces inside a nuclear power plant. The device includes a pump, a nozzle connected to the pump and arranged to face surfaces to be cleaned. The device includes cleaning means capable of removing debris on surfaces to be cleaned. The device includes one or more adjustable flotation means, capable of adjusting the flotation capability of the device depending on cleaning application. The flotation means provides for the altering of the behaviour of the device depending on if it is to be cleaning a horizontal surface or a vertical surface. On a horizontal surface, same weight is preferable, but not too much as it otherwise will make the device difficult or heavy to control and to propel. On the other hand, if generally vertical surfaces are to be cleaned, it is preferable that the device is weight balanced to float or to be weight neutral in water, in order to facilitate the operation along the walls and for safe recovery in case contact is lost with the device during operation. According to one solution, the flotation means comprises exchangeable flotation bodies having different flotation capabilities. One body having one flotation capability is replaceable with another body displaying a different flotation capability. In one embodiment, the flotation means includes a fillable volume capable of containing different volumes of flotation gas. The flotation capabilities are alterable by adding or removing gas from the volume. According to one preferable solution according to the present invention, the cleaning mechanism includes cleaning members capable of directing the removed debris towards the nozzle. This facilitates collection of the debris and dirt removed by the cleaning mechanism, thereby also reducing the risk that removed debris is spread in the water of the pool or other volume where the device is being operated. In one embodiment, the cleaning mechanisms include rotatable members in contact with the surface to be cleaned. The rotating movement is advantageous in that it is accomplished by drive motors, and also that the rotation causes the removed debris in a certain direction. Preferably, one cleaning mechanism is applied on each of two opposite sides of the device, which collect debris and particles from two directions. Alternatively, a front mechanism collect and move debris towards the nozzle while the rear mechanism prevents debris from leaving the device even though the nozzle may miss a fraction of the collected debris. In one embodiment, the rotatable members include several different materials and designs such as comprise brushes, sponges, rakes or the like depending on the application and its the requirements and on the type of surface. As an alternative, or in addition, the cleaning mechanisms comprise nozzles capable of ejecting liquid or gas under high pressure, which nozzles are arranged on rotatable carriers. Furthermore, indirect mechanical techniques can be applied such as ultrasonic cleaning or pulsed laser cleaning, where cavitations or compressed air bubbles are generated to remove debris. Preferably the device includes further a remote control system for controlling the driving of the device, thereby improving the working conditions for the operator. With the present invention, it is feasible to further arrange it with a positioning system capable of tracking and storing the actual position of the device during the cleaning operation. Also additional sensors and devices capable of collecting data and information during the cleaning operation may be added to the device of the present invention. There may for example be graphical presentations displaying areas that have been cleaned and areas that are yet to be handled. These and other aspects of, and advantages with, the present invention will become apparent from the following detailed description of the invention and from the accompanying drawings. A non-limiting example of the present invention will be described below in conjunction with the accompanying drawings. Referring to FIG. 1, a device 100 for submersibly cleaning surfaces in a liquid in a nuclear power plant or repository for spent nuclear fuel includes a frame or the like central support 10. A plate 12 is attached to the central support 10. The plate 12 is arranged with at least one opening (not shown), preferably centrally, and the plate is formed such around that at least one opening that a nozzle is formed, facing downwards in FIG. 1, or functions as a suction nozzle as will be described below. A pump 14 is connected to the opening preferably via tube or hose. The pump 14 is capable of creating a high suction action at the nozzle. The pump is arranged with an outlet passage 16, which is connectable to a flexible conduit or hose 18, FIGS. 4 and 5. The hose 18 is then preferably connected to a purpose built filter, a collecting vessel or the like. The device 100 is further arranged with propelling means. The propelling means comprises in the embodiment shown an electric motor 20 attached to the frame and/or the pump 14. Preferably the electric motor 20 is drivably connected to a gear box 22. The gear box 22 is in turn arranged with two output shafts 24, which extend to the each side of the gear box. To each end of the shaft 24, a drive wheel 26 is arranged. The drive wheels 26 are arranged with profiles on their outer circumferences, like ledges. These ledges cooperate with corresponding ribs arranged on inner surfaces of drive caterpillar tracks 28. These tracks 28 also run along support wheels 30 arranged on shafts on the opposite side of the nozzle 12. At the both shafts of the propelling means, cleaning mechanisms 32 are arranged. Still referring to FIG. 1, one cleaning mechanism 32 is arranged on a first end 60 of the device 100 and a second cleaning mechanism 32 is arranged on an opposing second end 62 of the device. As shown in FIG. 1, each cleaning mechanism 32 spans a width W of the device 100. As shown in FIG. 3, each cleaning mechanism 32 comprises an elongated hollow shaft 34. Each elongated hollow shaft 34 is rotatably journalled on fixtures 36 arranged to the device 100. The fixtures 36 are preferably turnably arranged as will be described below. On the shaft 34, cleaning members 38 are arranged, which, in one embodiment, are rotatable and could be tubularly shaped brushes, sponges, scrapes or the like capable of removing dirt, debris and the like on the surfaces to be cleaned. Some examples of different types of cleaning members 38 are shown in FIG. 2. The shaft 34 carrying the cleaning members 38 is rotatably attached to at least one cog wheel 40, which cog wheel 40 in turn is meshed with a drive cog wheel 42, FIG. 2. This drive cog wheel 42 is attached to a drive shaft of an electric motor 44 in turn attached to one of the fixtures 36 of the cleaning mechanisms. Each electric motor 44 is arranged to rotate such that the cleaning members 38 rotate to push the dirt and debris towards the center of the device 100 and thus the nozzle. The overall design of the cleaning mechanisms 32 is to provide a self-supported unit and to minimize the risk of small components entering the reactor pool or similar environments in case of a breakage. This may be seen in the cross-sectional view of FIG. 3. It will be appreciated that since each cleaning mechanism 32 includes a cleaning member 38, the cleaning members 38 also span a width W of the device 100. As shown in FIGS. 4 and 5, the device 100 according to the invention is further arranged with flotation means 50. The flotation means 50 are adapted to alter the flotation capabilities of the device 100 depending on the cleaning application. In the embodiment shown the flotation means 50 is a volume of material that is capable of altering the flotation capability when submerged in water. In one embodiment, the flotation means 50 is foamed plastic that can hold an amount of air. In one embodiment, the flotation means 50 is a balloon or enclosure that can be filled with air. Depending on the type of application, different flotation capabilities are desired. FIG. 4 discloses a device according to the present invention when used on a generally horizontal surface. Here it is advantageous that the device 100 just about sinks. When the pump is started, the suction action from the nozzle will steady the device on the horizontal surface and will allow the propelling means to make the device 100 go forward or backward on the surface. Thus there is a certain balance between the suction action and the overall sinking weight of the device. Further, in this application when the device 100 is used on horizontal surfaces, the cleaning mechanisms 32 will be moved in contact with the surface due to turnable attachment and due to the gravitation. If the device 100 according to the invention is to be used on generally vertical surfaces, it is advantageous that it just about floats. Then the flotation means 50 is altered to obtain these features, FIG. 5. In one embodiment the volume of foamed plastic is exchanged to another volume having better flotation capabilities. In another embodiment, containing a volume to be filled with air, a larger volume of air may be introduced. Again, in use, the pump 14 is activated, causing a suction action which draws the device against the vertical surfaces to be cleaned. The propelling means are then activated to drive the device up and down along the surfaces. In this application, a positioning mechanism (not shown) is used in order ascertain a good contact of the cleaning members 38 against the surface to be cleaned since the gravity cannot be used. The positioning means may for example be spiral springs, elastic elements or the like capable of turning the cleaning members 38 against the surface. For both horizontal and vertical applications, it is preferable to have safety line 52 so that the device 100 may be brought back up after use. The application for vertical surfaces may further be arranged with a support or stand 56, FIG. 5, such that the device 100 may rest in the vertical position when it has reached a horizontal surface. For both horizontal and vertical applications, a remote control unit is preferably utilized, with which an operator may drive the device 100 during the cleaning action. In this context it is of course feasible to use a monitoring means such as a camera mounted on the device, which will provide the user with visual information. Also, even if mechanical cleaning members 38 have been described above, it is of course feasible to use other types of cleaning members 38 such as pressurized water jets, pressurized air jets, ultra-sonic waves, pulsed laser to mention a few. Then a number of nozzles may be arranged to cover the width of the device, where the nozzles may be positioned inclined on a rotating carrier so that the jets sweep over the surface. Preferably the jets are also directed such that any removed debris or dirt is directed towards the suction nozzle. Further possibilities are to equip the device 100 with position monitoring means, whereby the actual position of the device may be obtained. This can be used to monitor the surfaces that have been cleaned and the surfaces that remain to be cleaned. It is further possible to provide the device 100 with additional devices such as sensors and the like for obtaining additional information. The information could for example be radioactive activity at certain locations, the status of welds in the reactor tank, taking samples from the reactor tank, just to mention a few. It is to be understood that the embodiment described above and shown in the drawings is to be regarded only as a non-limiting example of the invention and that it may be modified in many ways within the scope of the patent claims.
	abstract	Exemplary pellets can be used for magnetic fusion devices for mitigating plasma disruption. In some embodiments, the pellets may be cryogenically cooled that may cause a rise in the electrical conductivity of the pellets. A high conductivity of the pellet can screen out the plasma's magnetic field from the interior of the pellet. The screening out of the plasma's magnetic field can slow the ablation rate of the pellet which may allow for deeper pellet penetration and a better suited spatial profile of deposited material for proper mitigation of the plasma disruption. In some other embodiments, the pellets may not be cryogenically cooled.
	abstract	A particle-beam projection processing apparatus for irradiating a target, with an illumination system for forming a wide-area illuminating beam of energetic electrically charged particles; a pattern definition means for positioning an aperture pattern in the path of the illuminating beam; and a projection system for projecting the beam thus patterned onto a target to be positioned after the projection system. A foil located across the path of the patterned beam is positioned between the pattern definition means and the position of the target at a location close to an image of the aperture pattern formed by the projection system.
048511854	claims	1. In a system having a pool of liquid in which a radiation emitting component is immersed for shielding said component with respect to radiation emitted by said component, the method of shielding a portion of such component extending above the upper surface of the liquid of said pool which comprises: surrounding the portion of the upper end of said component which extends above the upper surface of said pool of liquid with a vessel having a top end wall and a side wall, said top end wall being disposed above and spaced from the extending upper end of said component and said side wall extending around and being disposed with said side wall spaced from the sides of said component and with the lower end of said side wall extending into said pool of liquid; and evacuating gas in said vessel to draw liquid from said pool into said vessel until the upper level of the surface of said liquid in said vessel is above said extending upper end of said component. 2. The method as set forth in claim 1 wherein said vessel has an open lower end and after said component is immersed in said pool, said vessel is lowered over said component with said lower end lowermost and said gas is pumped from the upper portion of said vessel by pumping means connected for fluid flow with the interior of said vessel and to said end wall. 3. The method as set forth in claim 1 wherein after said upper level of the surface of said liquid is above said upper end of said component, the last-mentioned said level is maintained until it is desired to expose said component at which time gas is admitted into said vessel to cause the level of the upper surface of the liquid in said vessel to lower. 4. The method as set forth in claim 1 wherein the interior dimensions of said vessel are selected in relation to the interior dimensions of said upper portion of said component so as to provide an amount of said liquid between said top end wall and said side wall sufficient to reduce the amount of radiation from said component and outside said vessel to no more than one-twentieth the amount of radiation in the absence of said amount of liquid between said top end wall and said side wall and said upper portion of said component. 5. The method as set forth in claim 4 wherein said interior dimensions of said vessel are selected to provide at least two feet of said liquid between the interior of said vessel and the exterior of said upper portion of said component.
	abstract	A TEM sample holder is formed by cutting the TEM sample holder form from a coupon in a press. The cutting at the same time joins the tip point of a nano-manipulator probe tip with the formed TEM sample holder. The tip point of the probe has a sample attached for inspection in a TEM. The cutting process also creates a gap in the sample holder to allow for FIB milling of the specimen.
	summary
048633119	claims	1. A lining for boreholes in salt domes for the storage of radioactive materials comprising superimposed tubular sections; each tubular section being made of a metallic material and including an outer ring and an inner ring joined together by an intermediate ring, said intermediate ring being of an electrochemically nobler material than the inner and the outer ring, the said tubular sections being welded together by welds between adjacent intermediate rings, said inner rings having a smaller axial dimension than the outer and intermediate rings so as to define a set of axially spaced recesses along the inside of the lining, the outer rings having an inner surface engaging directly on the intermediate ring at a location spaced inwardly of the upper and lower edges of said intermediate ring so as to define upper and lower recesses, a support ring disposed in each said recess and being made of the same material as the intermediate ring and being welded to the intermediate ring. 2. A lining according to claim 1 wherein handling recesses are formed in the inner rings. 3. A lining according to claim 1 wherein the inner rings and outer rings are made of spherical cast graphite. 4. A lining according to claim 2 wherein the inner rings and outer rings are made of spherical cast graphite.
062467417	description	DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail in conjunction with what are presently considered preferred or typical embodiments thereof with reference to the accompanying drawings. In the following description, like reference characters designate like or corresponding parts throughout the several views. Now, description will be made of the fuel assembly according to a first embodiment of the present invention with reference to FIGS. 1 to 3. The fuel assembly according to the embodiment of the invention is comprised of a lower nozzle 2 disposed on a lower core plate 1, an upper nozzle 4 having hold-down springs 3 for pressing and holding down the lower nozzle 2 against the lower core plate 1, a plurality of control rod guide thimbles 5 for guiding control rods extending through the upper nozzle 4 toward the lower core plate 1, a plurality of support grids 6 mounted onto the control rod guide thimbles 5, and a number of fuel rods 7 held in parallel with the control rod guide thimbles 5 by the support grids 6. The lower nozzle 2 is constituted by a plate portion 2a formed in a square shape, and having four leg portions 2b formed on the bottom surface at four corners thereof respectively. A number of coolant flow holes are opened in the plate portion 2a of the lower nozzle 2. Additionally, a number of thimble mounting holes normally corresponding to the number of the control rod guide thimbles 5 are opened in the plate portion 2a. In each of the thimble mounting holes, a thimble mounting bolt 8 (see FIG. 2) is inserted from the bottom side of the lower nozzle 2. Lower end portions of the control rod guide thimbles 5 are secured onto the top surface of the lower nozzle 2 by means of these thimble mounting bolts 8. The upper nozzle 4 is formed as a box-like structure having a central recess formed in a top cover portion thereof, wherein a plurality of control rod receiving through-holes 9 are formed in the upper nozzle 4 (see FIG. 3). These control rod receiving through-holes 9 are provided in correspondence to the control rod guide thimbles 5, respectively, wherein a connecting pipe 10 is welded to each of the control rod receiving through-holes 9 for connecting the top end portion of the control rod guide thimble 5 to the upper nozzle 4. The connecting pipe 10 has an inner diameter slightly greater than the outer diameter of the control rod guide thimble 5. The control rod guide thimble 5 and the connecting pipe 10 are joined together by a bulging process. Each of the supporting grids 6 comprises a frame with a square shape, and a number of metal plates assembled together inside of the square frame, wherein a plurality of sleeves 11 are secured to the metal plates by welding. The sleeves 11 are provided for mounting each of the supporting grids 6 to the control rod guide thimbles 5, wherein the associated control rod guide thimble 5 and sleeve 11 are joined together by a bulging process. The control rod guide thimbles 5 are formed in the shape of a straight tube, wherein a lower end portion of each control rod guide thimble 5 is provided with a dashpot 12. The dashpot 12 is designed to dampen an impact force applied to the upper nozzle 4 by reducing the falling speed of the control rod upon detachment thereof from the control rod driving unit. With "L" representing the length of the control rod guide thimble 5, the dashpot 12 has a length ranging from 0.16 L to 0.18 L. Further, a large diameter section 13a is formed at a lower portion of each dashpot 12, while the upper portion of each dashpot 12 is formed as a small diameter section 13b. The outer diameter of the large diameter section 13a is dimensioned to be approximately equal to that of the control rod guide thimble 5. The length of the dashpot 12, exclusive of the large diameter section 13a, i.e., the effective length S of the small diameter section 13b, is so selected as to fall within a range of from 0.03 L to 0.1 L, preferably within a range of from 0.04 L to 0.06 L, wherein "L" represents the entire length of the control rod guide thimble 5. Consequently, the length S' of the large diameter section 13a is dimensioned to be within a range of from 0.06 L to 0.15 L and preferably within a range of from 0.10 L to 0.14 L. FIG. 4 is a graph illustrating the results of analysis concerning the relationship between the impact force F applied to the upper nozzle 4 when the control rods are detached from the associated control rod driving unit and the length of the dashpot 12, exclusive of the large diameter section 13a; i.e., the effective length S of the small diameter section 13b. As can be seen from this figure, the effective length S of the small diameter section 13b of the dashpot 12 should preferably be greater than 0.03 L in order to make the impact force F applied to the upper nozzle 4 smaller than the permissible limit value F.sub.0. Next, FIG. 5 is a graph illustrating the results of analysis concerning the relationship between the flexural rigidity of the dashpot 12 and the effective length S of the small diameter section 13b of the dashpot. As can be seen from this figure, when the effective length S of the small diameter section 13b of the dashpot is selected to be equal to 0.1 L, the flexural rigidity of the dashpot 12 increases by about 15% compared to the conventional dashpot employed in the fuel assembly known heretofore. Further, when the effective length S of the small diameter section 13b of the dashpot is selected to be S=0.05 L, the flexural rigidity of the dashpot 12 increases by about 30% compared to the conventional dashpot. Thus, it can be understood from the foregoing description that when the effective length S of the small diameter section 13b of the dashpot 12, exclusive of the large diameter section 13a, is selected so as to fall within the range of 0.03 L to 0.1 L and preferably within a range of 0.04 L to 0.06 L, the impact force F applied to the upper nozzle 4 upon detachment of the control rods can be suppressed to be smaller than the permissible limit value F.sub.0, and the flexural rigidity of the dashpot 12 can be increased as well. Thus, the dashpot 12 can be protected against flexural deformation under a compression load acting in the axial direction of the control rod guide thimble 5. Furthermore, the present invention is not intended to be limited to the embodiment described above, and numerous modifications maybe conceived. By way of example, in the case of the fuel assembly described above, the outer diameter of the lower end portions of the dashpots 12 is formed so as to be approximately equal to that of the control rod guide thimble 5. However, the outer diameter of the lower end portions of the dashpots 12 may be formed smaller than that of the control rod guide thimbles 5 as shown in FIG. 6, which shows the fuel assembly according to a second embodiment of the present invention. As is apparent from the foregoing description, with the arrangement of the present invention, since large diameter sections having approximately the same diameter as that of the control rod guide thimbles are formed in lower portions of the dashpots and the length of the dashpot, exclusive of the large diameter section, i.e., the length of the small diameter section, is selected so as to lie within a range of 0.03 L to 0.1 L (where L represents the entire length of the control rod guide thimble), a fuel assembly can be realized in which the dashpots of the control rod guide thimbles are protected against flexural deformation which may otherwise occur under the compression loads acting in the axial or longitudinal direction of the control rod guide thimbles. Many modifications and variations of the present invention are possible in the light of the above techniques. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced other than as specifically described.
054421861	claims	1. An encapsulated radioactive isotope source which permits re-encapsulation and reuse of the radioactive isotope and which comprises: an outer protective jacket in the form of a can having a side wall, an integrally formed bottom wall and an open upper end; a source capsule containing a radioactive isotope, said source capsule being received within said outer protective jacket; a jacket cap received within said outer protective jacket so as to close the open end of said jacket, with said source capsule located therewithin, said jacket cap having its outer peripheral edge positioned in close-fitting relation to the inner peripheral surface of said jacket side wall to form a narrow gap between the jacket cap and said jacket side wall; a score line formed on the exterior of said outer protective jacket; and a seal extending along said narrow gap to join said jacket cap to said jacket and to seal said source capsule within the protective jacket. an outer cylindrical protective metallic jacket in the form of a can having a cylindrical side wall, an integrally formed bottom wall and an open upper end; a source capsule containing a radioactive isotope, said source capsule being received within said outer protective jacket with one end thereof facing said bottom wall of the jacket and with an opposite end thereof facing said open upper end thereof; a spacer plug received within said outer protective jacket overlying said opposite end of said source capsule; a score line formed on the exterior of said outer protective jacket at a location opposite the underlying spacer plug; a cylindrical jacket cap received within said outer protective jacket overlying said spacer plug, said jacket cap having its outer peripheral edge surface positioned in close-fitting relation to the inner peripheral surface of said jacket side wall to thereby close the open end of said jacket and to form a narrow annular gap between the jacket cap and the axially endmost surface of the side wall of said protective jacket; and a weld extending along and filling said narrow annular gap to join said cylindrical jacket cap to said outer protective jacket and to thereby seal the protective jacket. positioning a source capsule containing a radioactive isotope within an outer protective jacket in the form of a can having a side wall, an integrally formed bottom wall, a score line formed on the exterior of said outer protective jacket, and an open upper end; positioning a jacket cap within said outer protective jacket so as to close the open end of said jacket with said source capsule located therewithin, said jacket cap having its outer peripheral edge positioned in close-fitting relation to the inner peripheral surface of said jacket side wall to form a narrow gap between the jacket cap and said jacket side wall; and forming a seal extending along said narrow gap to join said jacket cap to said jacket and to seal said source capsule within the protective jacket. positioning said source capsule containing a radioactive isotope within another outer protective jacket in the form of a can having a side wall, an integrally formed bottom wall, a score line formed on the exterior of said outer protective jacket, and an open upper end; positioning another jacket cap within said another outer protective jacket so as to close the open end of said jacket with said source capsule located therewithin, said another jacket cap having its outer peripheral edge positioned in close-fitting relation to the inner peripheral surface of said jacket side wall to form a narrow gap between the jacket cap and said jacket side wall; and forming a seal extending along said narrow gap to join said jacket cap to said jacket and to seal said source capsule within the protective jacket. positioning a source capsule containing a radioactive isotope within an outer cylindrical protective metallic jacket in the form of a can having a cylindrical side wall, an integrally formed bottom wall, a score line formed on the exterior of said outer protective jacket, and an open upper end, with one end of the source capsule facing said bottom wall of the jacket and with an opposite end thereof facing said open upper end thereof; positioning a spacer plug within said outer protective jacket overlying said opposite end of said source capsule; positioning a cylindrical jacket cap within said outer protective jacket overlying said spacer plug, said jacket cap having its outer peripheral edge surface positioned in close-fitting relation to the inner peripheral surface of said jacket side wall to thereby close the open end of said jacket and to form a narrow annular gap between the jacket cap and the axially endmost surface of the side wall of said protective jacket; and forming a weld extending along said narrow annular gap to join said jacket cap to said jacket and to seal said source capsule within the protective jacket. positioning a source capsule containing a radioactive isotope within another outer cylindrical protective metallic jacket in the form of a can having a cylindrical side wall, an integrally formed bottom wall, a score line formed on the exterior of said outer protective jacket, and an open upper end, with one end of the source capsule facing said bottom wall of the jacket and with an opposite end thereof facing said open upper end thereof; positioning a spacer plug within said another outer protective jacket overlying said opposite end of said source capsule; positioning another cylindrical jacket cap within said outer protective jacket overlying said spacer plug, said jacket cap having its outer peripheral edge surface positioned in close-fitting relation to the inner peripheral surface of said jacket side wall to thereby close the open end of said jacket and to form a narrow annular gap between the jacket cap and the axially endmost surface of the side wall of said protective jacket; and forming a weld extending along said narrow annular gap to join said jacket cap to said jacket and to seal said source capsule within the protective jacket. 2. A source according to claim 1 additionally including a spacer plug located within said jacket between said source capsule and said jacket cap. 3. A source according to claim 2 wherein said spacer plug has a cross-sectional area substantially corresponding to the inside dimensions of said jacket and has its outer periphery positioned in close-fitting relation to the inner peripheral surface of said jacket side wall. 4. A source according to claim 2 wherein said score line is formed on the exterior of said outer protective jacket at a location opposite the underlying spacer plug. 5. A source according to claim 1 wherein the juncture between the exposed outward facing surface of said jacket cap and the adjoining outer peripheral edge surface of said jacket cap forms a V-shaped recess along said narrow gap, and wherein said seal comprises a weld located within said V-shaped recess. 6. A source according to claim 1 wherein the exposed outward facing surface of said jacket cap includes an outward facing raised perimeter portion where said weld contacts the jacket cap and a recessed outward facing central portion surrounded by said perimeter portion. 7. An encapsulated radioactive isotope source which permits re-encapsulation and reuse of the radioactive isotope and which comprises: 8. A source according to claim 7 wherein said spacer plug is of a cylindrical configuration and has its outer circumferential surface positioned in close-fitting relation to the inner peripheral surface of said side wall. 9. A source according to claim 7 wherein the juncture between the exposed outward facing surface of said jacket cap and the adjoining outer peripheral edge surface of said jacket cap forms a chamfered corner defining one side of said gap, and the juncture between the exposed end surface of said jacket side wall and the adjoining inner peripheral surface of said jacket side wall forms a chamfered corner defining the other side of said gap, said chamfered corners being in substantial alignment with one another along said gap and forming a V-shaped recess, and said weld is located within said V-shaped recess. 10. A method of re-encapsulating and reusing a radioactive isotope source which comprises: 11. A method according to claim 10 additionally including positioning a spacer plug within said jacket between said source capsule and said jacket cap. 12. A method according to claim 10 including the steps of separating the jacket cap from said jacket to reopen the protective jacket, removing the source capsule from said jacket, and carrying out the following steps with a new protective jacket and a new jacket cap to re-encapsulate said source capsule: 13. A method of re-encapsulating and reusing a radioactive isotope source which comprises: 14. A method according to claim 13 including the steps of separating the jacket cap from said jacket, removing the source capsule from said jacket, and carrying out the following steps with a new protective jacket and a new jacket cap to re-encapsulate said source capsule:
	abstract	A head assembly of a reactor pressure vessel in an ice condenser plant is retrofitted to permit the assembly to be removed during a later refueling operation in reduced time and with reduced exposure to radiation by operating personnel. The portions of the ductwork ventilation system that originally provided cooling air to CRDMs are removed below the seismic support platform. The original CRDM cooling shroud that surrounds the lower portion of the CRDM assemblies is extended to the seismic support platform. A plenum is mounted on the seismic support platform and in air flow communication with interior portion of the extended CRDM cooling shroud. The plenum fits under the missile shield. Spool pieces are connected between the plenum and the portion of the ductwork adjacent to the seismic support platform. Later, during refueling operations, the RPV head assembly can be disconnected from and reconnected to the ductwork of the ventilation system without the need for scaffolding around the RPV head assembly and with reduced exposure to radiation by operating personnel.
	description	This application is a divisional of U.S. application Ser. No. 10/692,646, filed Oct. 24, 2003, herein incorporated by reference. The present invention relates to fuel for nuclear reactors. More specifically, the present invention provides a nuclear reactor fuel and a process for making a nuclear reactor fuel which exhibits enhanced thermal conductivity as compared to conventionally used uranium dioxide nuclear reactor fuel. Present-day nuclear power reactor fuels in use for commercial power generation are based on uranium dioxide. The uranium dioxide fuel is commonly a product of several manufacturing steps including pressing a uranium dioxide powder into a pellet shape and subsequently firing the pellet to remove any formed voids. The wide-spread use of uranium dioxide fuel is due primarily to the many desirable characteristics of the uranium dioxide material, including a high density of uranium atoms necessary for producing a nuclear reaction, inertness and insolubility of the uranium dioxide in high temperature water, a high melting point and an absence of neutron poisons which could affect reactor performance. Although uranium dioxide is satisfactory for use in light water reactors, uranium dioxide also has several significant drawbacks which limit its overall effectiveness. Chief among the drawbacks is a relatively low thermal conductivity of uranium dioxide which imposes significant limitations on reactor operations. The inability of uranium dioxide to remove large quantities of heat effectively limits overall reactor operation and also compromises reactor operations during transient events such as loss of coolant accidents (LOCA). The nuclear industry has made attempts to increase thermal conductivity of uranium dioxide fuel, but none of the attempts have been successful. Despite the drawbacks, uranium dioxide, in unmodified form, remains the dominant fuel for nuclear power reactors. In general, heat produced in nuclear fuel must be conducted through the body of the fuel, normally in the pelletized form, and an external cladding, normally a zirconium alloy, to a surrounding coolant layer in order to properly cool the fuel and prevent pellet degradation. The surrounding coolant layer is moved past the external cladding to provide a consistent temperature for removal of heat from the fuel. During transient reactor conditions, such as when the coolant flows past the external cladding unevenly, the steady removal of heat from the pellet is disrupted. During loss-of-coolant accidents, operational safety is compromised due to accumulating heat in the fuel and the inability of the uranium dioxide matrix to withstand the increased temperatures. This thermal conductivity characteristic of conventional uranium dioxide fuel necessitates operating the reactor at reduced power in order to achieve acceptable overall plant safety margins. Operating the reactor at the reduced power levels consequently affects overall plant operating costs. Current nuclear fuels using uranium dioxide also have a limited burn-up capacity. The limited burn-up capacity reduces the overall cost effectiveness of the fuel. The limited burn-up capacity results from greater fission gas release inside the fuel cladding over time. The greater fission gas release thereby results in higher fuel rod internal pressure, potentially leading to cladding deterioration due to the higher stress. The elevated temperatures of the existing fuel also stresses the fuel cladding thereby limiting overall service life. There is a need to provide a nuclear fuel which will provide enhanced thermal conductivity compared to conventional uranium dioxide fuel currently used in nuclear power reactors. There is a further need to provide a nuclear fuel which will result in greater safety of the nuclear reactor under accident conditions, such as loss of coolant accidents. There is a still further need to provide a nuclear fuel which will possess superior burn-up capabilities compared with conventional uranium dioxide nuclear fuels, thereby allowing greater fuel utilization, improved economy, and limited fission gas release. It is an object of the present invention to provide a nuclear fuel which provides enhanced thermal conductivity compared to conventional uranium dioxide nuclear fuel currently used in nuclear power reactors. It is also an object to provide a nuclear fuel which will result in greater safety of the nuclear reactor under accident conditions, such as loss of coolant accidents. It is furthermore an object of the present invention to provide a nuclear fuel which will possess burn-up capabilities superior to that of conventional uranium dioxide fuels, thereby allowing greater fuel utilization and limiting fission gas release. These and other objects of the present invention are achieved as illustrated and described. The invention provides a method to produce uranium dioxide fuel which has increased thermal conductivity compared to conventional nuclear fuel. The method recites providing a porous uranium dioxide arrangement, infiltrating the porous uranium dioxide arrangement with a precursor liquid, and thermally treating the porous uranium dioxide arrangement with the infiltrated precursor liquid such that the precursor liquid is converted to a second phase. The invention also provides a nuclear fuel. The present invention recites an arrangement having a matrix of uranium dioxide and silicon carbide interspersed in the matrix of uranium dioxide. The present invention provides a nuclear fuel and a method to make the nuclear fuel. Referring to FIG. 1, a uranium dioxide arrangement 10 is provided for processing. The uranium dioxide arrangement 10 may be in any shape, such as a pellet, ball or rod for example. The uranium dioxide arrangement 10 should have a porous matrix to allow infiltration of material into the arrangement 10 when contacted by a precursor liquid 12. The porous matrix of the uranium dioxide arrangement 10 can be formed, for example, by pressing uranium dioxide powder into a “green” or unfired shape. The porous matrix may also be formed by a bisque firing that does not fully densify the uranium dioxide arrangement 10. A liquid precursor 12 is added to the uranium dioxide arrangement 10 to infiltrate the uranium dioxide matrix. The precursor liquid 12 may be, for example, allylhydridopolycarbosilane (AHPCS). The precursor liquid 12 can be configured to penetrate the porous matrix of the uranium dioxide arrangement 10 without damaging the overall uranium dioxide matrix configuration. The uranium dioxide arrangement 10 may be sprayed or, as illustrated, immersed in the liquid precursor 12, to cause contact between the arrangement 10 and the liquid precursor 12. The composition of the precursor liquid 12 allows incorporation of the precursor liquid 12 into the pores of the porous matrix of the uranium dioxide arrangement 10. The time of contact of the precursor liquid 12 to the uranium dioxide arrangement 10 may be chosen such that incorporation of the precursor liquid 12 into all of the pores in the uranium dioxide matrix occurs in a single contact cycle, for example. To promote infiltration of the precursor 12 into the arrangement 10, the arrangement may be evacuated before infiltration, or the precursor may be applied under pressure, or both. Alternatively, the precursor liquid 12 may contact the uranium dioxide arrangement 10 for a time such that a single contact cycle does not result in incorporation of the precursor liquid 12 into all of the pores of the porous matrix. After the precursor liquid 12 has contacted the uranium dioxide arrangement 10 and been incorporated into the matrix of the arrangement 10, at least partially, the arrangement 10 may then be cured. Curing 14 may be through placement of the uranium dioxide arrangement 10 into a furnace 16 between, for example, 180 degrees centigrade and 400 degrees centigrade. Curing time may be, for example, between 2 hours and 8 hours. Other curing times and temperatures may be used. The curing 14 process converts the precursor liquid 12 into a solid polymer, wherein the solid polymer is positioned in the matrix of the uranium dioxide arrangement 10. Next, the arrangement 10 is then thermally treated 18 such that the polymer positioned in the uranium dioxide arrangement 10 is converted to a second phase. In the current exemplary embodiment of the invention, the allylhydridopolycarbosilane, which has turned into a polymer in the uranium dioxide arrangement 10 from the curing operation, is converted into silicon carbide through firing the arrangement 10 in a furnace 20. The furnace temperatures may be chosen, for example, from between 800 degrees centigrade to 1700 degrees centigrade. The residence time for the uranium dioxide matrix in the furnace 20 may be, for example, 2 hours to 8 hours. Other residence times may be used such that the polymer is converted into silicon carbide. Residence times may be varied to minimize ultimate volume change of the pellet. The resulting product is a nuclear fuel which has silicon carbide incorporated into the matrix of the uranium dioxide. The method steps of infiltrating the porous uranium dioxide arrangement 10 with a precursor liquid 12 and thermally treating the porous uranium dioxide arrangement 10 with the infiltrated precursor liquid 12, which can include both the curing and the firing of the arrangement, may then be repeated, if desired, to allow more incorporation of precursor liquid 12 into the matrix of the uranium dioxide if total incorporation has not occurred. The present invention provides an increase in the thermal conductivity of nuclear fuel thereby resulting in increased fuel performance during loss of coolant accidents. The present invention also provides for reduced fuel temperatures and internal fuel pellet heat. Due to the possibility of creating overall geometric sizes similar to the geometries used in conventional reactors, existing nuclear power reactors may utilize fuel described in the present invention. Furthermore, through the use of the nuclear fuel with increased thermal conductivity, existing reactors may be operated at higher power levels to provide superior economic performance. Maximum fuel burn-up is also increased as lower overall fuel temperatures limit fission gas release, thereby limiting fuel rod internal pressure. Superior fuel burn-up also allows less waste to be produced for ultimate disposal. The reduced fuel temperatures also reduce the stresses imposed on the cladding, reduce fuel cracking and relocation and reduce life-limiting fuel swelling. Use of silicon carbide is compatible with existing light-water reactors, thermally, chemically and neutronically. New reactor systems, therefore, do not have to be created in order to utilize a fuel containing silicon carbide. The thermal conductivity of silicon carbide is high so that substantial increases in overall fuel thermal conductivity can be achieved with only a small decrease in the density of uranium atoms. As an example, a thermal conductivity of 50 percent is expected for a 10 percent volume loading of silicon carbide. Advantages for a process of producing a nuclear fuel using silicon carbide incorporated into the matrix of the arrangement include the limited addition of an infiltration station and an inert-gas curing/firing furnace with provision for combustion of hydrogen offgassed from the precursor to existing facilities used for production of nuclear fuel. The process of the current application also allows the precursor liquid to penetrate the entire body of the fuel arrangement so that the resulting second phase, after thermal firing, penetrates to the center of the pellet, thereby producing a uniform overall fuel product. The second phase of the invention may form as a continuous network rather than as discontinuous particles, so the overall fuel pellet is effective in conducting heat from the core of the fuel pellet to the exterior surface. Additionally, the liquid infiltrant produces a high yield of the second phase, so the infiltration and conversion process need only be repeated a few times. The current invention provides an advantage over processes mixing powders of uranium dioxide and silicon carbide in that for small volume fractions, the second phase forms discrete particles which are thermally insulated by the uranium dioxide. For large volume fractions, an excessive amount of uranium is displaced affecting overall fuel composition. The current invention also provides an advantage over chemical vapor infiltration for placement of silicon carbide on uranium dioxide. Such chemical vapor infiltration methods produce uneven placement of silicon carbide on an exterior of a fuel element with higher concentrations of silicon carbide on the exterior of the fuel. Costly equipment is needed for deposition of the chemical vapor on the uranium dioxide. Placement of the chemical vapor is also uneven, resulting in a final product widely varying composition. Additionally, methyltrichlorosilane, used in the deposition of silicon carbide, results in hydrogen chloride gas production as a waste product, thereby complicating waste disposal issues and increasing overall cost. The current invention additionally provides advantages over mixing uranium dioxide with whiskers of silicon carbide. The whiskers, discrete arrangements of silicon carbide, prevent effective sintering of the arrangement. Moreover, silicon carbide whiskers mixed with a uranium dioxide powder would result in uneven silicon carbide distribution. In the foregoing specification, the invention has been described with reference to specific exemplary embodiments, thereof. It will, however, be evident that various modifications and changes may be made thereunto without departing from the broader spirit and scope of the invention as set forth in the claims. The specification and drawings are accordingly to be regarded in an illustrative rather than a restrictive sense.
048044989	claims	1. A process for treating radioactive waste liquid comprising: a first step of converting a soluble component comprising sodium sulfate or sodium borate contained in the radioactive waste liquid into an insoluble substance by adding a soluble barium compound when the soluble component comprises sodium sulfate or a soluble calcium compound when the soluble component comprises sodium borate and precipitating the insoluble substance; a second step of adding an adsorbent for absorbing radioactive substances, said adsorbent being selected from the group consisting of a titanium compound, a zirconium compound and a metal ferrocyanide; a third step of separating caustic soda formed in the precipitate; a fourth step of solidifying a slurry containing the precipitate with a hydraulic solidifying material; and a fifth step of removing said separate caustic soda for reuse of said separated caustic soda. a first step of adding an additive to the radioactive waste liquid for converting a soluble component comprising sodium sulfate or sodium borate contained in the radioactive waste liquid into an insoluble substance and for precipitating the insoluble substance and adding an adsorbent for adsorbing radioactive substances, said additive being a soluble barium compound when the soluble component comprises sodium sulfate or a soluble calcium compound when the soluble compound comprises sodium borate, and said adsorbent being selected from the group consisting of a titanium compound, a zirconium compound and a metal ferrocyanide; a second step of separating caustic soda formed in conversion of the radioactive waste liquid into the insoluble substance; a third step of solidifying a slurry of the radioactive waste liquid separated from said caustic soda with a hydraulic solidifying material; and a fourth step of removing said separated caustic soda for reuse of said separated soda. a first step of converting a soluble component comprising sodium sulfate or sodium borate contained in the radioactive waste liquid into an insoluble substance by adding a soluble barium compound when the soluble component comprises sodium sulfate or a soluble calcium compound when the soluble component comprises sodium borate and precipitating the insoluble substance; a second step of adding an adsorbent for adsorbing radioactive substances, said adsorbent being selected from the group consisting of a titanium compound, a zirconium compound and a metal ferrocyanide; a third step of separating caustic soda formed in the precipitate; a fourth step of powdering the precipitate by drying; a fifth step of solidifying the dried powder by adding water and a hydraulic solidifying material; and a sixth step of removing said separated caustic soda for reuse of said separated caustic soda. a first step of adding an additive to the radioactive waste liquid for converting a soluble component comprising sulfate or sodium borate contained in the radioactive waste liquid into an insoluble substance and for precipitating the insoluble substance and adding an adsorbent for adsorbing radioactive substances, said additive being a soluble barium compound when the soluble component comprises sodium sulfate or a soluble calcium compound when the soluble component comprises sodium borate, and said adsorbent being selected from the group consisting of a titanium compound, a zirconium compound and a metal ferrocyanide; a second step of separating caustic soda formed in conversion of the radioactive waste liquid into the insoluble substance; a third step of powdering by drying a slurry of the radioactive waste liquid from which caustic soda is separated; a fourth step of solidifying the dried powder by adding water and a hydraulic solidifying material; and a fifth step for removing said separated caustic soda for reuse of said separated caustic soda. 2. A process for treating radioactive waste liquid according to claim 1, wherein said adsorbent is copper ferrocyanide. 3. A process for treating ratioactive waste liquid according to claim 1, wherein said slurry is powdered by drying, and said fourth step is performed by adding a hydraulic solidifying material. 4. A process for treating radioactive waste liquid according to claim 1, wherein said slurry is concentrated by evaporation, and said fourth step is performed by adding a hydraulic solidifying material. 5. A process for treating radioactive waste liquid according to claim 1, wherein the separated caustic soda is passed through a filter member filled with an adsorbent for absorbing of radioactive substances. 6. A process for treating radioactive waste liquid according to claim 1, wherein before the third step, the precipitate is concentrated by evaporating a moisture component of the precipitate. 7. A process for treating radioactive waste liquid comprising: 8. A process for treating radioactive waste liquid according to claim 7, wherein adding the adsorbent for adsorption of the radioactive substances is performed in advance of adding the additive for converting the soluble component contained in the radioactive waste liquid into the insoluble substance and for precipitating the insoluble substance. 9. A process for treating radioactive waste liquid according to claim 7, wherein the slurry is concentrated by evaporation of a moisture component of the slurry in advance of the third step of solidifying the slurry with the hydraulic solidifying material. 10. A process for treating radioactive waste liquid comprising: 11. A process for treating radioactive waste liquid comprising: 12. A process for treating radioactive waste liquid according to claim 1, wherein the second step of adding an adsorbent is performed simultaneously with the first step of converting and precipitating.
	abstract	A disposal device comprises a raw material conveyor, a raw material mixer, a liquid waste conveying pipeline, an additive tank, a powder waste conveyor, an output pump, a liquid supply pump, a liquid supply manifold, an output manifold, a mixed liquid conveying pipeline, a high-pressure injection pump, a high-pressure pipeline, and a wellhead sealing device. A method of employing the device includes: drilling a well; forming a fracture in the granite stratum; preparing a raw material; and injecting, by using the disposal device, a sand-carrying feed liquid from a high-pressure injection pump into the fracture of the underground granite stratum, so as to perform solidification.
	description	The present application claims priority from Japanese applications JP 2008-122657 filed on May 8, 2008, the content of which is hereby incorporated by reference into this application. The present invention relates to a recipe parameter management system and a recipe parameter management method for use with the same for managing recipe parameters of a review system to observe a surface of a planar substrate such as a semiconductor wafer. Foreign matters and defects taking place in a circuit pattern formed on a wafer surface in semiconductor manufacturing processes cause defects in the semiconductor products such as integrated circuits manufactured through the semiconductor manufacturing processes. To cope with the difficulty, whether or not a problem takes place in the manufacturing processes is continuously monitored by quantifying the state of occurrence of foreign matter and circuit pattern defects (to be referred to as wafer pattern defects hereinbelow) in a semiconductor manufacturing line. Also, by precisely observing the contour of a wafer pattern defect, whether or not the defect fatally affects the semiconductor product is also confirmed. Conventionally, such defects have been visually observed by a human. Recently, by using apparatuses such as Automatic Defect Review (ADR) and Automatic Defect Classification (ADC) based on the image processing techniques employing a computer, it is possible to automatically determine the size, the contour, and the kind of the defects (reference is to be made to, for example, JP-A-2007-40910 and JP-A-2007-184565). Since a large amount of defect data items can be obtained in a short period of time due to such automatizing functions, it is possible to efficiently narrow a range of, for example, the cause of defects. However, if the defect under consideration is a defect which fatally affects yield of the products, it is inevitable to rely on the visual inspection by a human in the final stage of confirmation of the defect. Hence, there still remain chances in which an engineer or operator observes defects by a review system and chances in which an engineer or operator checks images of defects automatically created by the review system. On the other hand, in the review system, sensors are improved in their performance such as sensitivity thereof and various functions become increasingly complicated. As a result, load imposed on the engineer or the operator who operates the review system is not mitigated, but rather increased. To reduce the load, for example, JP-A-2006-173589 describes an example in which by effectively employing the Graphical User Interface (GUI), operability is improved in the operations ranging from the defect observation to the image collation which are repeatedly carried out in the defect analysis. With recent development of functions and performance of the review system, the operation to determine an optimal review condition to review defects by the review system imposes heavy load on the engineer and the operator. However, in JP-A-2007-40910, JP-A-2007-184565, and JP-A-2006-173589, description has not been given of a method of efficiently determining the optimal review condition. The operation to determine the optimal review condition is an operation to be first conducted when the review system is used. Ordinarily, the optimal review condition is obtained by conducting a trial review several times. The obtained condition is recorded as a so-called recipe parameter for each review target or each purpose. However, in the present stage of art, a technique to systematically utilize recipe parameters gathered in the past has not been established. Therefore, the operation efficiency in the obtaining the optimal review condition of the review system relies on skills and experiences of the engineer or the operator who operates the review system. As the review system, a Scanning Electron Microscope (SEM) is used in many cases. In operation of the SEM, each time an observed image created by the SEM is obtained, surfaces of a semiconductor integrated circuit or the like as the review target are charged, and hence there remain SEM contamination marks. Hence, the number of trial reviews increases, and it becomes difficult to view the image of a defect to be inherently reviewed or the image cannot be viewed depending on cases. Therefore, it is desired to reduce the number of trial reviews in the operation to determine the optimal review condition. It is therefore an object of the present invention, which has been devised in consideration of the above problem, to provide a recipe parameter management system and a recipe parameter management method in which in the operation to determine the optimal review condition, the number of trial reviews is reduced and the operation efficiency is improved. In order to achieve the object according to the present invention, there is provided a recipe parameter management system which collects and manages data including setting values of recipe parameters during the defect review from the review system. The recipe parameter management system collects, as recipe parameter setting history data for the defect review conducted by the review system, data items including the setting values of recipe parameters set in the defect review, the number of trial reviews carried out to set the recipe parameters, and defect images of defects gathered in the defect review, and then stores the history data in a predetermined storage. On the basis of the recipe parameter setting history data stored in the storage, the recipe parameter management system generates a histogram for the recipe parameter setting values and displays the generated histogram and the number of trial reviews for each recipe parameter. In short, when a defect review is carried out in the review system, the recipe parameter management system stores the recipe parameter setting values and the number of trial reviews in the storage such that when a defect review is next conducted, the management system displays the histogram of the setting values and the number of trial reviews for each recipe parameter. Hence, the engineer or operator conducting the defect review easily obtains the recipe parameter values set in the past defect reviews and can recognize a trend of difficulty of parameter setting for a recipe parameter under consideration on the basis of the histogram of setting values and the number of trial reviews for the pertinent recipe parameter. According to the present invention, in the operation to determine an optimal review condition in the review system, the number of trial reviews can be reduced and hence efficiency of the operation is improved. 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. Referring now to the drawings, description will be given in detail of an embodiment of the present invention. FIG. 1 shows an example of structure of an overall system to which an embodiment of a recipe parameter management system is applied according to the present invention. As FIG. 1 shows, a recipe parameter management system 3 is employed, for example, to manage recipe parameters in a review system 10 arranged in a wafer manufacturing line 1. The wafer manufacturing line 1 includes a plurality of process steps 11 disposed in a so-called clean room. In the process steps 11, patterns of devices and metal interconnections are sequentially formed on a silicon wafer to manufacture an integrated circuit or the like. There is disposed, after the last process step 11, a probe inspection system or prober 15 in which integrated circuits or the like formed on the wafer are electrically inspected to obtain quality control information such as production yield. Each process step 11 includes, according to necessity, a wafer pattern inspection system 12, an optical review system 13, and an electron beam review system 14 (the systems 12 to 14 will be collectively referred to as a review system 10 hereinbelow). In the wafer pattern inspection system 12, foreign matter and defects appearing in each process step 11 are inspected and the number and size of the foreign matter pieces and those of the defects are obtained as quality control information of the process step 11. For example, if the obtained quality control information indicates an unacceptable condition for the process step 11, detailed states of foreign matter pieces and defects are observed by the review system 10 according to necessity. In FIG. 1, a line management system 2 is connected via a network 4 including a Local Area Network (LAN) or the like to the wafer pattern inspection system 12, the review system 10, and the prober 15. The line management system 2 collects defect information of defects of wafers flowing through the process steps 11 from, for example, the wafer pattern inspection system 12, and manages the collected defect information. Specifically, from the wafer pattern inspection system 12, the line management system 2 collects defect information pieces such as a defect IDentifier (ID) of a defect detected by the wafer pattern inspection system 12, coordinates of a position of the defect, Realtime Defect Classification (RDC) information, an ADR image and the like, and then relates the defect information pieces to a lot number of a wafer under consideration, a wafer ID of the wafer, a die layout position, and the like. Further, the line management system 2 adds a process name and information of day and time of the associated inspection to the defect information pieces and stores the resultant information pieces in a database (DB), not shown, for management thereof. The recipe parameter management system 3 is connected, like the line management system 2, via the network 4 to the wafer pattern inspection system 12, the review system 10, and the prober 15. Primarily, the recipe parameter management system 3 collects recipe parameter setting history data of the defect review conducted by the review system 10 and manages the collected data. Also, the management system 3 assists the operation which is conducted by the engineer or operator (to be simply referred to as an operator hereinbelow) to set optimal values of recipe parameters by using the review system 10. When the defect review is conducted in the review system 10, the line management system 2 transmits defect information, which includes coordinates of a position of a defect and which is obtained from the wafer pattern inspection system 12, to the review system 10. However, since it is required to transmit quite a large amount of defect information pieces in ordinary cases, the defects are appropriately filtered according to, for example, a defect size and a coordinate position of the defect, and then defect information pieces obtained by filtering the defects are transmitted to the review system 10. The review system 10 obtains detailed ADR images and detailed ADC information pieces for the defect associated with the received defect information. Further, according to indications from the operator, the review system 10 obtains images of defects and defect classification information to send the obtained defect images and the obtained defect classification information (including the ADR image and the ADC information in some cases) to the line management system 2. when the defect images and the defect classification information are received, the line management system 2 stores the defect images and the defect classification information in the database, not shown, with a relationship established to the defect information beforehand sent to the review system 10, for the management thereof. Description will now be given in detail of a configuration and a function of the recipe parameter management system 3 in the embodiment according to the present invention. FIG. 2 shows an example of a functional block configuration of the recipe parameter management system 3. As FIG. 2 shows, the recipe parameter management system 3 includes a center processing apparatus 30 including a personal computer, a workstation, or the like, and terminal(s) 40 connected directly to or via a LAN, not shown, to the center processing apparatus 30. Moreover, the recipe parameter management system 3 is coupled via the network 4 with the review system 10 (FIG. 1). The terminal 40 may be a terminal of any kind only if it includes a communication function to communicate with the center processing apparatus 30, a display, and an input unit including a mouse, keyboard, and the like. For example, the computer employed for operations and display in the review system 10 may be adopted as the terminal 40. As FIG. 2 shows, the center processing apparatus 30 includes functional blocks, i.e., a recipe parameter setting history data collector 31, a recipe parameter setting history DB 32, a histogram generator 33, a filtering processing section 34, a histogram display section 35, a filtering condition setting section 36, an image comparing and displaying section 37, a recipe parameter setting section 38, and a recipe parameter output section 39. Each function of these functional blocks is implemented when a Central Processing Unit (CPU), not shown, of the center processing apparatus 30 executes a predetermined program stored in a storage (a Random Access Memory (RAM), a hard disk, or the like), not shown. In FIG. 2, the recipe parameter setting history data collector 31 receives recipe parameter setting history data sent from the review system 10 to store the received data in the recipe parameter setting history DB 32. The other functional blocks of the center processing apparatus 30 will be described in conjunction with FIG. 4 and subsequent drawings. FIG. 3 shows an example of a layout of the recipe parameter setting history data sent from the review system 10. When a defect review is conducted in a review system 10, the recipe parameter setting history data is obtained as history data of recipe parameters finally set to the review system 10. The recipe parameter setting history data also includes image data of defects obtained in the defect review. That is, the recipe parameter setting history data is created each time a defect review is carried out. Specifically, as FIG. 3 shows, the recipe parameter setting history data includes data items such as a process step name, a recipe name, day and time, a parameter type, a parameter name, a parameter value, an edit frequency, and image data. The process step name and the recipe name are used as information pieces to identify the purpose of the defect review and the review system 10 in which the defect review is conducted. The parameter type, the parameter name, and the parameter value are a set of data items corresponding to each recipe parameter. Hence, the number of these sets of data items is equal to that of the recipe parameters to be set to the review system 10 in which the defect review is carried out. Among the set of data items, the parameter type and the parameter name are information pieces to identify a recipe parameter. Hence, these data items may be concatenated by a hyphen with each other to be treated as one information piece. The edit frequency indicates the number of trial reviews which are repeatedly conducted in the review system 10 by changing the parameter value of the pertinent recipe parameter until the parameter value is finally determined for the recipe parameter. Hence, the edit frequency may be regarded as a value indicating the trial-and-error operations or difficulty imposed on the operator to determine the value for the recipe parameter. The image data is data of defect images actually obtained by the review system 10 when the parameter values of the recipe parameter setting history data are set as recipe parameters in the review system 10. The recipe parameter setting history data described above is text data excepting the field of image data. The field of image data includes data in the format of, for example, Joint Photographic Experts Group (JPEG). FIG. 4 shows an example of a histogram display screen of recipe parameter setting values. As FIG. 4 shows, for each recipe parameter designated by the parameter type 104 and the parameter name 105, the histogram display screen 100 displays a histogram 106 of setting values of the recipe parameter and a bar graph 111 of the edit frequency thereof. The center processing apparatus 30 displays the histogram display screen 100 for the processing of the histogram generator 33. That is, when a histogram display request is received via the terminal 40, the center processing apparatus 30 first displays the process step name 101 and the recipe name 102 in the form of, for example, a pulldown menu. When a process step name and a recipe name are selected using the pulldown menu, the apparatus 30 extracts, from the recipe parameter setting history DB 32, recipe parameter setting history data having the selected process step name and the selected recipe name and then sorts the selected data using the parameter type 104 and the parameter name 105 as sorting keys. Next, the center processing apparatus 30 generates, for the processing of the histogram generator 33, a histogram 106 using the recipe parameter setting values, i.e., parameter values of the recipe parameter setting history data sorted as above. Further, based on the edit frequency of the sorted recipe parameter setting history data, the apparatus 30 generates a bar graph 111 representing the edit frequency of the associated recipe parameters. Subsequently, the center processing apparatus 30 displays, for the processing of the histogram display section 35, the histogram 106 of the recipe parameter setting values and the bar graph 111 of the edit frequency, which are generated as described above, on the terminal 40. In the histogram display screen 100, the minimum, central, and maximum values displayed over the histogram 106 respectively indicate the minimum, central, and maximum values of the parameter value available in the review system 10. Incidentally, for convenience of display, these values are normalized as, for example, “central value=0”, “maximum value=1”, and “minimum value=−1”. It is assumed in the histogram display screen 100 that the histogram 106 and the bar graph 111 of the edit frequency are displayed for all recipe parameters specified by the parameter type 104 and the parameter name 105. However, if the histograms 106 and the bar graphs 111 overflow one screen image, the concealed section of the histograms 106 and that of the bar graphs 111 are displayed by the scroll display function through operation of a scroll bar 109. The histogram 106 of recipe parameter setting values generated and displayed as above represents the distribution of frequency of parameter values set by many operators in the defect reviews conducted in the past. Hence, if a recipe parameter has a frequency distribution having a large variance (dispersion), it is implied that various values have been set to the recipe parameter and there exists difficulty in the setting of the parameter value. That is, in an operation to set the parameter value of a recipe parameter for which the frequency distribution of the parameter values has a large variance (dispersion), the operator is required to be carefully set the parameter value. On the other hand, if a recipe parameter has a frequency distribution having a small variance (dispersion), the recipe parameter has the approximate same value in many past defect reviews. It is implied that the parameter value can be relatively easily set. It is predictable that no serious problem occurs even if an average value (or a value substantially equal to the average value) of the parameter values set in the past is employed in a defect review to be conducted. Similarly, the bar graph 111 of the edit frequency created as above represents an average number of trial reviews carried out until the parameter value is determined for the associated recipe parameter in the past defect reviews. That is, if a recipe parameter has a large edit frequency, it is indicated that the trial review is conducted many times until the final parameter value is determined by the defect review and it is implied that the recipe parameter cannot be easily determined. Hence, the operator is required to carefully set the parameter value of the recipe parameter. Contrarily, if a recipe parameter has a small edit frequency, it can be considered that the parameter value is relatively easily set. Furthermore, in FIG. 4, a parameter value setting cursor 110 is indicated by a vertical line in the histogram 106 of recipe parameter setting values. By moving the cursor 110 to the left or the right, the operator can appropriately designate a parameter value to be set. That is, the center processing apparatus 30 reads, for the processing of the recipe parameter setting section 38, the position of the parameter value setting cursor 110 from the histogram 106 to determine the current recipe parameter value based on the position. In the histogram display screen 100, check boxes 103 are displayed in front of the parameter type 104 and the parameter name 105 and a parameter selection button 112 is displayed for image comparison on the right-hand side of the bar graph 111 of the edit frequency. Also, to implement more precise functions, there are displayed a filtering button 107, an edit frequency button 108, a selection display button 117, an image comparison button 116, a recipe input button 115, a recipe output button 114, an end button 113 and the like. The image comparison button 116 is used to select recipe parameters such that images are compared with each other according to values of the selected recipe parameters to be displayed on the screen. The selection display button 117 is employed to display only the histograms of the selected recipe parameters. The edit frequency button 108 is used to display the histograms 106 of the recipe parameters by sorting the histograms 106 in an order of the edit frequency. The filtering button 107 is used to display a histogram 106 for each recipe parameter selected according to a predetermined filtering condition. The recipe input button 115 is employed to obtain, from the review system 10, a parameter value of each recipe parameter set when a defect review is conducted in the review system 10. The recipe output button 114 is used to output, to the review system 10, recipe parameters set in the center processing apparatus 30. The end button 113 is used to close the histogram display screen 100. Description will now be given of examples of functions to be executed and examples of screens to be displayed when these buttons are clicked. First, the image comparison and display function will be described by referring to FIGS. 5 and 6. FIG. 5 shows an example of the display screen indicating that one of the parameter selection buttons 112 is selected in the histogram display screen 100 of FIG. 4. FIG. 6 shows an example of the image comparison screen. If one of the parameter selection buttons (radio buttons) 112 indicated by small white circles is selected and is then clicked in the screen 100 of FIG. 4, the selected white circle is changed to a black circle to resultantly display a histogram display screen 100a as shown in FIG. 5. In the screen 100a, the black circle of the parameter selection button 200 indicates that a recipe parameter for which the parameter type is “parameter A” and the parameter name is “parameter A-1” has been selected as shown in FIG. 6. If the image comparison button 116 is clicked while the histogram display screen 100a is being displayed, the center processing apparatus 30 displays an image comparison screen 300 for the processing of the image comparison and displaying section 37. That is, the center processing apparatus 30 opens a new image comparison screen 300 and displays a histogram 306 with respect to a recipe parameter for which the parameter type is “parameter A” and the parameter name is “parameter A-1”. For each of the minimum, central, and maximum values of parameter values obtained from the histogram 306 (other than the minimum, central, and maximum values which can be set to the review system 10), the apparatus 30 displays in the screen 300 defect images 303, 304, and 305 which are obtained and stored in the recipe parameter setting history DB 32 in the past. In the histogram 306, a parameter value setting cursor 307 indicated by a vertical line is also displayed. By moving the cursor 307 to the right or the left, the operator can appropriately set the parameter value of the associated recipe parameter. When the operator clicks an execute button 308 displayed in a bottom section of the screen 300, the center processing apparatus 30 extracts from the history DB 32 a defect image which is obtained using a parameter value most similar to the current parameter value of the recipe parameter and displays the extracted defect image as a defect image 302 of the current setting value in the image comparison screen 300. Therefore, by setting various parameter values of the recipe parameter by use of the cursor 307 in the image comparison screen 300, the operator can easily confirm defect images which are obtained in the past and which correspond to the parameter values of the recipe parameter. Based on the defect images, the operator can easily determine an optimal value of the recipe parameter obtained in the past. That is, the optimal value of the recipe parameter can be determined without conducting trial reviews in the review system 10 or the trial-and-error procedure is not required to determine the optimal value of the recipe parameter. Therefore, the number of trial reviews can be reduced. According to the present embodiment, the condition to obtain the optimal recipe parameter can be more efficiently determined in the review system 10. If the review system 10 is an electron beam review system 14, it is possible that no contamination mark is or a reduced number of contamination marks are observed by the electro beam review system on a wafer as the review target. In the image comparison screen 300 of FIG. 6, if a shut button 309 or a close button 301 is clicked, the screen 300 is closed. Referring now to FIGS. 7 and 8, description will be given of the selection and display function of the histogram display. FIG. 7 shows an example of a display screen indicating that a check mark is removed from part of the check boxes in the histogram display screen 100 of FIG. 4. FIG. 8 shows an example of the histogram display screen after the check mark is removed. In the example of the histogram display screen 100b of FIG. 7, no check mark is displayed in the check box 103 for which the parameter type 104 is “parameter A”. In this situation, it is assumed that the check mark is removed from the check boxes 103 of all parameter names 105 belonging to the parameter type 104. In FIG. 7, when a check mark is inputted to the check boxes 103 on the left side of a parameter type 104 and an associated parameter name 105, a histogram 106 and a bar graph 111 of the edit frequency are displayed for a recipe parameter designated by the parameter type 104 and the parameter name 105. Hence, if the check mark is removed from one of the check boxes 103, the histogram 106 and the bar graph 111 are not displayed for the recipe parameter. In the histogram display screen 100b (FIG. 7) obtained by removing the check mark from the check box 103 for which the parameter type 104 is “parameter A”, if the selection and display button 117 is clicked, the center processing apparatus 30 displays a histogram display screen 100c as shown in FIG. 8. In the screen 100c, the system does not display the histogram 106 and the bar graph 111 for each recipe parameter belonging to “parameter A” for which the check mark is removed from the histogram display screen 100b of FIG. 7. In the examples of FIGS. 7 and 8, when the check mark for “parameter A” is removed, the histogram 106 and the bar graph 111 are not displayed for each recipe parameter belonging to “parameter A”. However, by removing the check mark on the left of the parameter name 105 without removing the check mark on the left of the parameter type 104, it is possible that the histogram 106 and the bar graph 111 are not displayed for each associated recipe parameter. If an all display button 117a for reverse display, which is difference from the display button 117, is clicked in the histogram display screen 100c of FIG. 8, the screen display returns to the original histogram display screen 100 of FIG. 4. Referring next to FIG. 9, description will be given of the sorting and display function using the edit frequency. FIG. 9 shows an example of a sorting and display screen generated according to the edit frequency. As FIG. 9 shows, the sorting and display screen 100d is produced by sorting data items displayed on the histogram display screen 100 of FIG. 4 in a descending order of the edit frequency. Specifically, if the edit frequency button 108 is clicked in the histogram display screen 100 of FIG. 4, the histogram 106 and the bar graph 111 of the edit frequency of each recipe parameter displayed in the screen 100 are sorted in a descending order of the edit frequency and are displayed again. As above, for a recipe parameter having a large edit frequency, an optimal value cannot be easily set and the operator is hence required to carefully set the value. In the sorting and display screen 100d, the histogram 106 and the bar graph 111 are displayed for each recipe parameter in the descending order of the edit frequency. Hence, only by viewing the screen 100d, the operator can easily recognize parameters to be carefully set. If the edit frequency button 108 is clicked in the sorting and display screen 100d, the sorted display screen is released and the display returns to the original histogram display screen 100. Referring now to FIGS. 10 and 11, description will be given of the filtering and display function. FIG. 10 shows an example of a filtering condition setting screen and FIG. 11 shows an example of a filtering and display screen. In the histogram display screen 100 of FIG. 4, if the filtering button 107 (“Filtering” in a frame 107 in FIG. 4 and in similar display screen examples) is clicked, the center processing apparatus 30 displays a filtering condition setting screen 500 of FIG. 10 for the processing of the filtering condition setting section 36. FIG. 10 shows two filtering conditions, i.e., a filtering condition based on the edit frequency and a filtering condition based on the parameter setting value. Specifically, in the setting screen 500, to set a filtering condition based on the edit frequency, input boxes 501 and 502 to input condition values of the edit frequency and check boxes 504 to select associated filtering conditions 505 are displayed. Four filtering conditions 505 shown in FIG. 10 are (1) edit frequency is more than condition value A and less than condition value B, (2) edit frequency is equal to or less than condition A, (3) edit frequency is equal to or more than condition value B, and (4) edit frequency is equal to or less than condition A or is equal to or more than condition value B, in this order. Also, in the filtering condition setting screen 500, to set a filter condition on the basis of a parameter setting value, filtering conditions 507 of associated parameter setting values and check boxes 506 to select the associated filtering conditions 507 are displayed. In this connection, the parameter setting value is a value set by the parameter setting value cursor 110 in the histogram 106 displayed in the histogram display screen 100. In the filtering condition 507, “sigma” indicates the standard deviation obtained from the histogram of recipe parameter setting values, and a value indicating a multiple of the standard deviation is inputted to the input box 507a. Each filtering condition 507 in this example is a condition to extract a filtering condition for which an associated parameter setting value is remarkably apart from the parameter setting values set in the past. In the filtering condition setting screen 500, if the execute button 508 is clicked after a check mark is inputted to one of the check boxes 504 to 506 and values are appropriately inputted to the input boxes 501, 502, and 507a for associated filtering condition values, the center processing apparatus 30 executes the processing of the filtering processing section 34 to display a filtering and display screen 100e as shown in FIG. 11. FIG. 11 shows an example of a display screen of histograms of recipe parameters after the filtering operation. Specifically, the center processing apparatus 30 extracts from the histogram display screen 100 of FIG. 4 recipe parameters (each recipe parameter including a pair of a parameter type 104 and a parameter name 105) conforming to the filtering condition specified in the filtering condition setting screen 500 and displays a filtering display screen 100e including histograms 106 and bar graphs 111 of the edit frequency corresponding to the extracted recipe parameters (FIG. 11). In the filtering condition setting screen 500, if a shut button 509 or a close button 503 is clicked, the screen 500 is closed. If the filtering button 107 is clicked while the filtering display screen 100e of FIG. 11 is displayed, the filtering is released and the display returns to the original histogram display screen 100. Due to the filtering and display function, it is possible that recipe parameters which are to be carefully set can be effectively extracted to be displayed for the operator. This hence helps the operator easily obtain histograms 106 of setting values of recipe parameters. In the histogram display screen 100 of FIG. 1 and the like, if the recipe output button 114 is clicked, the center processing apparatus 30 assumes, for the processing of the recipe parameter output section 39, that the values being currently set to recipe parameters are the optimal values of the recipe parameters and transmits the values to the review system 10. The operator of the review system 10 regards the recipe parameter values received from the center processing apparatus 30 as the optimal recipe parameter values for which the conditions have been determined. The operator hence can start the defect review for an actual wafer and the like. Alternatively, the operator of the review system 10 may use the recipe parameter values from the apparatus 30 as initial values to resultantly obtain the optimal parameter conditions in the review system 10. In either cases, it is possible to reduce the number of trial reviews in the review system 10. According to the present embodiment, in the recipe parameter management system 3, the operator can beforehand determine optimal recipe parameter conditions in an online fashion by use of the recipe parameters obtained in the past and associated defect images. Therefore, the number of trial reviews to be conducted in the review system 10 can be reduced. Resultantly, the operation to determine optimal recipe parameter conditions can be more efficiently carried out in the review system 10. The operator can easily obtain the histogram of the recipe parameter setting history and the information of the number of setting changes of each recipe parameter in the past. Hence, it is possible for the operator to easily determine recipe parameters for which the optimal parameters are required to be carefully determined. As a result, even an unexperienced operator can conduct the operation to determine optimal recipe parameter conditions. Also, the optimal values determined by the respective operators for each recipe parameter less deviate from each other between the operators. Therefore, the quality control and the defect analysis for wafers flowing through the wafer manufacturing line 1 can be efficiently carried out with high precision. This resultantly leads to improvement in yield of integrated circuits formed in wafers. Description will now be supplementarily given of a variation of the embodiment. In this embodiment, the recipe parameter management system 3 conducts the operation to obtain the recipe parameter optimal values in an offline manner on the basis of defect images obtained in the past. However, the operation may be carried out in an online manner. In such case, it is assumed that the terminal 40 is integrally disposed in the review system 10 or is arranged quite near the review system 10. Also, for example, the defect image 302 of the current setting values in the image comparison screen 300 (FIG. 6) is not extracted from the recipe parameter setting history DB 32, but an image actually obtained by the review system 10 is displayed as the defect image 302. Hence, the recipe parameter optimal values can be determined at a higher speed. As shown in FIG. 12, the recipe parameter management system 3 may be linked via the network 4 with the review systems 10 respectively set in a plurality of wafer manufacturing lines 1. In such situation, a larger amount of recipe parameter setting history information pieces are gathered in the recipe parameter setting history DB 32 of the management system 3. It is hence possible to determine optimal recipe parameter values with higher precision. In the embodiment, the defect review is conducted for silicon wafers in intermediate process steps to form integrated circuits and the like. However, the defect review may also be carried out for a liquid-crystal display substrate, an organic Electro-Luminescence display substrate, a magnetic disk substrate, and the like in intermediate process steps of production thereof. 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.
	abstract	A pressurized water nuclear reactor (PWR) has an internal pressurizer volume containing a steam bubble and is surrounded by a containment structure. A condenser is disposed inside the containment structure and is operatively connected with an external heat sink disposed outside of the containment structure. A valve assembly operatively connects the PWR with the condenser responsive to an abnormal operation signal such that the condenser condenses steam from the steam bubble while rejecting heat to the external heat sink and returns the condensed water to the PWR. A quench tank contains water with dissolved neutron poison. A valved tank pressurizing path selectively connects the steam bubble to the quench tank to pressurize the quench tank, and a valved soluble poison delivery path selectively connects the quench tank to the PWR such that the quench tank under pressure from the steam bubble discharges water with dissolved neutron poison into the PWR.
062597582	description	DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS It has been found that, by coating an alloy from the group consisting of carbon steel, alloy steel, stainless steel, nickel-based alloys, zirconium and cobalt-based alloys with a catalytically active material, or otherwise providing catalytic activity at such metal alloy surfaces, the decomposition of the hydrogen peroxide in aqueous process systems of nuclear reactors is catalysed by the catalytically active material. Such catalytic action at the surface of the alloy reduces the ECP of the alloy, thereby mitigating SCC of such alloy. Suitable coatings of catalytically active material can be deposited by methods well known in the art for depositing continuous or substantially continuous coatings on metal substrates, such as plasma spraying, chemical vapour deposition, physical vapour deposition processes such as sputtering, welding such as metal inert gas welding, electroless plating, and electrolytic plating. The catalytically active material can be a metal selected from the group consisting of manganese, molybdenum, zinc, copper, cadmium and mixtures thereof. Other suitable materials include oxides of these metals. Even further suitable materials can include chemical compounds containing these metals, where the metal in such compounds is able to dissociate and make itself available for reacting with oxygen to form an oxide. Manganese dioxide catalyzes the decomposition of hydrogen peroxide according to the following reaction mechanism: EQU H.sub.2 O.sub.2 +MnO.sub.2 +2H.sup.+.fwdarw.O.sub.2 +Mn.sup.2+ +2H.sub.2 O EQU Mn.sup.2+ +2H.sub.2 O.sub.2.fwdarw.Mn(OH).sub.2 +2H.sup.+ EQU Mn(OH).sub.2 +H.sub.2 O.sub.2.fwdarw.MnO.sub.2 +2H.sub.2 O EQU 2H.sub.2 O.sub.2.fwdarw.O.sub.2 +2H.sub.2 O It is believed that, by coating the surface of a metal alloy cooling tube of a water-cooled nuclear reactor with manganese, such component is able to maintain a lower ECP. This is because the manganese is believed to be oxidized to catalytically active manganese oxide (MnO.sub.2), which catalyses hydrogen perixode decomposition. Because very small surface concentrations are adequate to provide the necessary catalytic activity and reduce the corrosion potential of the metal, the processing as well as the physical, metallurgical or mechanical properties of the alloys and components formed therefrom are not significantly altered. Further, lower amounts of reducing species, such as hydrogen, are necessary to reduce the ECP of the metal components below the critical potential, because of the catalysed decomposition of hydrogen peroxide. As an alternative to coating the subject alloy with the catalytically active material, the catalytically active material may be injected in-situ in the process liquid for effecting decomposition of hydrogen peroxide, thereby reducing the ECP of the alloy. FIG. 4 shows the benefits of in-situ injection of manganese as Mn(NO.sub.3).sub.2.multidot.6H.sub.2 O for effecting decomposition of hydrogen peroxide. With each injection, there was a corresponding reduction in ECP of the alloy believed attributable to the decomposition of hydrogen peroxide. It is believed that the injected manganese oxidizes and precipitates out as MnO.sub.2 on the alloy surface. Once deposited on the surface, MnO.sub.2 effects the catalytic decomposition of hydrogen peroxide according to the above-described reaction mechanism. The present invention will be described in further detail with reference to the following non-limitative examples. EXAMPLE 1 A 304 SS electrode was placed in an autoclave recirculating loop, containing water at 288.degree. C. having 300 ppb hydrogen peroxide. Various concentration of dissolved Mn solution were injected directly into the autoclave where the 304 SS electrode was immersed and argon gas was continuously purged through this injection solution during the test. The ECP of the 304 SS electrode was measured over the course of 30 days using a Cu/Cu.sub.2 O/ZrO.sub.2 electrode. The measured ECP was converted to a standard hydrogen electrode (SHE) scale. FIG. 4 shows the ECP response of 304 SS electrode before, during, and after three different manganese solution injections to 288.degree. C. water containing 300 ppb hydrogen peroxide. It is evident that the addition of Mn to 300 ppb hydrogen peroxide water decreased the ECP of the 304 SS electrode. Once injections were ceased, the ECP of the 304 SS electrode remained lower than the corrosion potential observed before the injections were commenced. This indicates the possible deposition of manganese oxide on 304 SS oxide, with the concomitant catalytic decomposition of hydrogen peroxide by the deposited manganese. The presence of manganese was, in fact, confirmed by Auger electron spectroscopy, which confirmed a thin oxide layer of 2.about.4% by weight on the 304 SS surface, to a depth of 100.about.150 A. From the above test, the presence of manganese oxide on the metal surfaces enhances the decomposition of hydrogen peroxide, with a consequent decrease in ECP of the metal alloy. EXAMPLE 2 A 304 SS electrode was placed in an autoclave recirculating loop, containing water at 288.degree. C. having 100 ppb hydrogen peroxide. Zinc, as zinc oxide, was injected directly into the autoclave where the 304 SS electrode was immersed. The ECP of the 304 SS electrose was measured over the course of 25 days using a Cu/Cu.sub.2 O/ZnO.sub.2 electrode. The measured ECP was converted to a standard hydrogen electrode (SHE) scale. FIG. 5 shows the ECP response of 304 SS electrode before, during and after aqueous zinc oxide injection to 288.degree. C. water containing 100 ppb hydrogen peroxide. Clearly, once injection of the aqueous Zinc oxide began, ECP of the 304 SS became reduced. Once injection was stopped, the ECP of the 304 SS electrode remained lower than the corrosion potential observed before the injections were commenced. This indicates the possible deposition of zinc oxide on 304 SS, with the concomitant decomposition of hydrogen peroxide by the deposited zinc oxide. The present invention provides a number of important advantages. In particular, the present invention provides a metal alloy surface coated with a catalytically active material for the decomposition of hydrogen peroxide. By doing so, the ECP of such metal alloys is lowered, thereby reducing corrosion and, notably, mitigating the effects of stress corrosion cracking. This is particularly beneficially for components of water-cooled nuclear reactors, whose high temperature aqueous environment is conducive to such corrosion phenomena, and where the occurrences of such phenomena could lead to loss of coolant and consequent loss of reactor control. It will be understood, of course, that modifications can be made in the embodiments of the invention described herein without departing from the scope and purview of the invention. For a complete definition as to the scope of the invention, reference is to be made to the appended claims.
	description	This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2009-224505 filed on Sep. 29, 2009, of which the contents are incorporated herein by reference. 1. Field of the Invention The present invention relates to a radiographic image capturing apparatus and a radiographic image capturing method for irradiating an object to be examined of a subject with radiation emitted from a radiation source while an irradiated field of the radiation on a radiation detector is being delimited by a collimator, and converting the radiation that has passed through the object to be examined into a radiographic image with the radiation detector. 2. Description of the Related Art There have heretofore been developed biopsy apparatus for sampling a tissue of a biopsy region (e.g., a lesion region in a subject's breast) in an object to be examined of a subject and thoroughly examining the sampled tissue for a disease diagnosis. In order to sample the tissue reliably, the biopsy region needs to have its three-dimensional position specified in advance. It has been customary to carry out a stereographic image capturing process on a radiographic image capturing apparatus by irradiating the object to be examined with radiation from a radiation source disposed at two different angular positions and detecting the radiation that has passed through the object to be examined with a radiation detector to acquire two radiographic images of the object to be examined, and calculate a three-dimensional position of the biopsy region based on the acquired two radiographic images. The irradiated field of the radiation on the radiation detector is delimited in advance by a collimator which is disposed between the radiation source and the radiation detector, or more specifically the object to be examined that is positioned on the side of the radiation detector which faces the radiation source (see Japanese Utility Model Publication No. 54-032458 and Japanese Laid-Open Patent Publication No. 08-107891). As described above, the three-dimensional position of the biopsy region needs to be specified in advance in order to sample the tissue of the biopsy region reliably. Therefore, if the radiation is applied to at least the biopsy region in the stereographic image capturing process, then it is possible to calculate the three-dimensional position of the biopsy region based on the two radiographic images which include the biopsy region. However, the radiographic image capturing apparatus according to the related art has the irradiated field of the radiation fixed in all stereographic image capturing processes. In other words, the collimator does not adjust the irradiated field before and after each of the stereographic image capturing processes. During the stereographic image capturing processes, therefore, the radiation is also applied to body regions of the subject which have nothing to do with the calculation of the three-dimensional position of the biopsy region, and hence the subject is unduly exposed to the radiation. In the stereographic image capturing process, the biopsy region may not be included in the two radiographic images or either one of the two radiographic images due to a movement or positional or angular change of the object to be examined between stereographic image capturing processes or due to angular errors of the radiation source at the two angular positions. If the biopsy region is included in only one or neither of the two radiographic images, then the three-dimensional position of the biopsy region cannot be calculated accurately. As a result, the tissue of the biopsy region cannot properly be sampled by the biopsy apparatus. It is an object of the present invention to provide a radiographic image capturing apparatus and a radiographic image capturing method which prevent a subject from being unduly exposed to radiation and accurately calculate the three-dimensional position of a biopsy region in an object to be examined by reliably performing a stereographic image capturing process on the biopsy region. To achieve the above object, there is provided in accordance with the present invention a radiographic image capturing apparatus comprising a radiation source for applying radiation to an object to be examined of a subject, a radiation detector for detecting the radiation that has passed through the object and converting the detected radiation into a radiographic image, a collimator for delimiting an irradiated field of the radiation with respect to the radiation detector, the collimator being disposed between the radiation source and the object, a biopsy region positional information calculating unit for calculating a three-dimensional position of a biopsy region in the object based on two radiographic images which are acquired by the radiation detector in a stereographic image capturing process in which the radiation source disposed at least at two angles applies the radiation to the object, an irradiated field calculating unit for calculating a new irradiated field covering the biopsy region based on the calculated three-dimensional position of the biopsy region and the two angles, and a collimator control unit for controlling the collimator to change the irradiated field of the radiation in a next stereographic image capturing process to the new irradiated field. According to the present invention, there is also provided a radiographic image capturing method comprising the steps of performing a stereographic image capturing process by applying radiation from a radiation source disposed at least at two angles to an object to be examined of a subject while an irradiated field of the radiation with respect to the radiation detector is being delimited by a collimator, detecting, with the radiation detector, the radiation applied from the radiation source disposed at the two angles to acquire two radiographic images, calculating, with a biopsy region positional information calculating unit, a three-dimensional position of a biopsy region in the object based on the two radiographic images, calculating, with an irradiated field calculating unit, a new irradiated field covering the biopsy region based on the calculated three-dimensional position of the biopsy region and the two angles, and controlling the collimator with a collimator control unit to change the irradiated field of the radiation in a next stereographic image capturing process to the new irradiated field. With the radiographic image capturing apparatus and the radiographic image capturing method described above, based on the three-dimensional position of the biopsy region which is obtained in a present stereographic image capturing process, an irradiated field (new irradiated field) of the radiation in a next stereographic image capturing process is calculated, and the next stereographic image capturing process is performed with the calculated new irradiated field. Since the radiation is applied in the new irradiated field around the biopsy region in the next stereographic image capturing process, the radiation is prevented from being applied to body regions of the subject which have nothing to do with the calculation of the three-dimensional position of the biopsy region, and hence the subject is prevented from being unduly exposed to the radiation. Even if the object is moved or positionally or angularly changed between stereographic image capturing processes or the radiation source disposed at the two angles suffers angular errors, since the new irradiated field around the biopsy region is irradiated with the radiation in the next stereographic image capturing process, two radiographic images acquired in the next stereographic image capturing process reliably cover the biopsy region. Consequently, it is possible to perform a stereographic image capturing process on the biopsy region and to accurately calculate the three-dimensional position of the biopsy region regardless of a movement or positional or angular change of the object or angular errors of the radiation source. According to the present invention, therefore, the subject is prevented from being unduly exposed to the radiation, and a stereographic image capturing process is reliably performed on the biopsy region in the object to be examined to accurately calculate the three-dimensional position of the biopsy region. The application of the radiation to the object from the radiation source at the two angles, the calculation of the three-dimensional position of the biopsy region by the biopsy region positional information calculating unit, the calculation of the new irradiated field by the irradiated field calculating unit, and the changing of the irradiated field of the radiation to the new irradiated field by the collimator control unit may successively be carried out repeatedly. Accordingly, the present stereographic image capturing process can be performed while reflecting the result (the three-dimensional position of the biopsy region) of the previous stereographic image capturing process, and the next stereographic image capturing process is performed while reflecting the result of the present stereographic image capturing process. As a result, even if the object is moved or positionally or angularly changed between stereographic image capturing processes or the radiation source disposed at the two angles suffers angular errors, the radiation source can apply the radiation to the object to be examined within a new irradiated field around the biopsy region. In other words, the radiation source applies the radiation to the object while at the same time tracking the biopsy region. The radiographic image capturing apparatus may further comprise irradiated field calculation control unit for selectively enabling the irradiated field calculating unit to calculate the new irradiate field or disabling the irradiated field calculating unit from calculating the new irradiate field. If any movement or positional or angular change of the object between stereographic image capturing processes is small, then the irradiated field calculation control unit enables the irradiated field calculating unit to calculate the new irradiated field for thereby preventing the subject from being unduly exposed to the radiation. On the other hand, if the object is greatly moved or positionally or angularly changed between stereographic image capturing processes, then the irradiated field calculation control unit disables the irradiated field calculating unit from calculating the new irradiated field, and the radiation is applied to the object to be examined in a wider irradiated field, for thereby allowing the biopsy region to be reliably covered by a radiographic image. The radiographic image capturing apparatus may further comprise a light source for spotlighting the radiation detector to indicate the irradiated field thereon, before the radiation source applies the radiation to the object. It is thus easy to confirm whether there exists any obstacle to a stereographic image capturing process between the radiation source and the object to be examined, before the stereographic image capturing process is carried out. The above and other objects, features, and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of illustrative example. A radiographic image capturing apparatus and a radiographic image capturing method according to a preferred embodiment of the present invention will be described below with reference to FIGS. 1 through 10 of the accompanying drawings. The basic structure of a mammographic apparatus 12 serving as the radiographic image capturing apparatus according to an embodiment of the present invention which incorporates a biopsy apparatus 10 will be described below with reference to FIGS. 1 and 2. The mammographic apparatus 12 basically includes an upstanding base 14, a vertical arm 18 fixed to the distal end of a swing shaft 16 disposed substantially centrally on the base 14, a radiation source housing unit 28 fixed to an upper end of the arm 18 and housing therein a radiation source 26 for applying radiation 24 to a breast 22 as an object to be examined of an examinee (subject) 20, an image capturing base 32 mounted on a lower end of the arm 18 and housing therein a solid-state detector (radiation detector) 30 for detecting the radiation 24 which has passed through the breast 22, a compression plate 34 for compressing and holding the breast 22 against the image capturing base 32, and a biopsy hand assembly 38 for removing a tissue sample from a biopsy region 36 of the breast 22, the biopsy hand assembly 38 being mounted on the compression plate 34. In FIGS. 1 and 2, the mammographic apparatus 12 applies the radiation 24 to the breast 22 of the examinee 20 and a sample tissue is removed from the biopsy region 36, while the breast 22 of the examinee 20 who is in a sitting position is being compressed and secured by the compression plate 34 and the image capturing base 32. To the base 14, there is connected a display control panel 40 for displaying image capturing conditions representing an image capturing region, etc. of the examinee 20, the ID information of the examinee 20, etc., and setting these items of information, if necessary. As shown in FIG. 1, when the arm 18, to which the radiation source housing unit 28 and the image capturing base 32 are secured, is angularly moved about the swing shaft 16, the direction of the radiation source housing unit 28 and the image capturing base 32 with respect to the breast 22 of the examinee 20 is adjusted. The radiation source housing unit 28 is operatively coupled to the arm 18 by a hinge 42 and can be turned about the hinge 42 in the directions indicated by the arrow θ independently of the image capturing base 32. The arm 18 has a groove 44 defined vertically in a side (front side) thereof which faces the examinee 20 in the direction indicated by the arrow X. The groove 44 extends along the direction indicated by the arrow Z. Handles 43 are mounted on the respective sides of the arm 18 which face away from each other along the direction indicated by the arrow Y. The handles 43 are gripped by the examinee 20. As shown in FIGS. 1 and 2, the compression plate 34 has a proximal end inserted in the groove 44 and held in interfitting engagement with a mount, not shown, disposed in the arm 18. The compression plate 34 that is thus coupled to the arm 18 is disposed between the radiation source housing unit 28 and the image capturing base 32. The compression plate 34 is displaceable in unison with the mount along the arm 18 in the directions indicated by the arrow Z when the mount is displaced along the groove 44 in the directions indicated by the arrow Z. The compression plate 34 has an opening 48 defined therein near a chest wall 46 (see FIG. 2) of the examinee 20, for allowing the biopsy hand assembly 38 to remove a tissue sample from the biopsy region 36 of the breast 22. The biopsy hand assembly 38 serves as part of the biopsy apparatus 10 which is incorporated in the mammographic apparatus 12. The biopsy hand assembly 38 comprises a post 50 fixedly mounted on the compression plate 34, a first arm 52 having an end pivotally supported on the post 50 and angularly movable about the post 50 along the surface of the compression plate 34, and a second arm 54 having an end pivotally supported on the other end of the first arm 52 and angularly movable about the other end of the first arm 52 along the surface of the compression plate 34. A biopsy needle 56 is mounted on the other end of the second arm 54 for movement in the directions indicated by the arrow Z. As shown in FIG. 2, the biopsy needle 56 has a sampler 58 for sampling under suction a tissue (e.g., a calcified tissue) from the biopsy region 36, which is a lesion area (e.g., a calcified area) of the breast 22. The sampler 58 of the biopsy needle 56 can be moved to a position in the vicinity of the biopsy region 36 when the first arm 52 and the second arm 54 of the biopsy hand assembly 38 are moved in an X-Y plane parallel to the surface of the compression plate 34 and the biopsy needle 56 is moved in the directions indicated by the arrow Z. The radiation source housing unit 28 also houses therein, in addition to the radiation source 26, a collimator 60 for delimiting an irradiated field of the radiation 24 emitted from the radiation source 26, a light source 62 and a mirror 64 for spotlighting the breast 22 to indicate the irradiated field of the radiation 24 thereon before the radiation 24 is actually emitted from the radiation source 26. The mirror 64 is disposed between the radiation source 26 and the collimator 60 and is made of a material permeable to the radiation 24. As shown in FIG. 3, the collimator 60 comprises a base 68 having a rectangular opening 66 defined therein, and four elongate rectangular shield plates 70a, 70b, 70c, 70d mounted on the base 68 for independent movement in the directions indicated by the arrows X, Y. The shield plates 70a, 70b have ends movably engaging a guide rail 72 on the base 68 and opposite ends including racks 74a, 74b which are held in mesh with respective pinions 78a, 78b rotatable by respective motors 76a, 76b mounted on the base 68. Similarly, the shield plates 70c, 70d have ends movably engaging a guide rail 80 on the base 68 and opposite ends including racks 74c, 74d which are held in mesh with respective pinions 78c, 78d rotatable by respective motors 76c, 76d mounted on the base 68. The shield plates 70a, 70b, 70c, 70d delimit the position and area of an opening 82 for the radiation 24 to pass therethrough. Before the radiation 24 is actually emitted from the radiation source 26, the light source 62 emits illuminating light, not shown. The illuminating light emitted from the light source 62 is reflected by the mirror 64 toward the collimator 60 through the opening 82 of the collimator 60 to the outside (near the breast 22). FIG. 4 shows in block diagram the mammographic apparatus 12 including the biopsy apparatus 10. As shown in FIG. 4, the mammographic apparatus 12 includes an image capturing selector 90, an image capturing condition setting section 92, a radiation source controller 94, a light source controller 96, a collimator controller (collimator control unit) 98, a detector controller 100, an image information storage unit 102, a CAD (Computer Aided Diagnosis) processor 104, a display unit 106, a biopsy region selector 108, a biopsy region positional information calculator (biopsy region positional information calculating unit) 110, a biopsy needle controller 112, a biopsy needle positional information calculator 114, a compression plate controller 116, a compression plate positional information calculator 118, a traveled distance calculator 120, an angle setting unit 122, an irradiated field calculation controller (irradiated field calculation control unit) 124, and an irradiated field calculator (irradiated field calculating unit) 126. The biopsy hand assembly 38, the biopsy needle 56, the opening 48, the biopsy region selector 108, the biopsy needle controller 112, the biopsy needle positional information calculator 114, and the traveled distance calculator 120 jointly make up the biopsy apparatus 10. The biopsy apparatus 10 which is incorporated in the mammographic apparatus 12 is capable of sampling part of a tissue of the biopsy region 36. The image capturing condition setting section 92 sets image capturing conditions including a tube current and a tube voltage of the radiation source 26, an irradiation dose and an irradiation time of the radiation 24, an image capturing method such as a scout image capturing process or a stereographic image capturing process (see FIGS. 5 through 7), and an imaging sequence. The stereographic image capturing process includes details about stereographic image capturing angles (two of 0°, +θ1, and −θ1 in FIGS. 5 through 7), three-dimensional positions of the radiation source 26 at the imaging capturing angles, radiation angles (θB1, θB2, θC1, θC2) which delimit an irradiated field of the radiation 24 when the radiation 24 is applied at the image capturing angles, and positional information of the shield plates 70a through 70d in a stereographic image capturing process. The three-dimensional position of the radiation source 26 specifies an image capturing angle, and the positional information of the shield plates 70a through 70d specifies a radiating angle. Therefore, the three-dimensional position of the radiation source 26 or the image capturing angle, and the positional information of the shield plates 70a through 70d or the radiating angle may be set at least in the image capturing condition setting section 92 as image capturing conditions for the image capturing method representative of the stereographic image capturing process. The radiation source controller 94 energizes the radiation source 26 according to the image capturing conditions. The light source controller 96 energizes the light source 62 according to the image capturing conditions before the radiation source 26 is energized. The collimator controller 98 energizes the motors 76a through 76d (see FIG. 3) of the collimator 60 according to the image capturing conditions to displace the shield plates 70a through 70d for thereby delimiting the position and area of the opening 82 for the radiation 24 to pass therethrough. The biopsy needle controller 112 controls the biopsy hand assembly 38 (see FIGS. 1 and 2) to move the biopsy needle 56 to a desired position. The compression plate controller 116 moves the compression plate 34 in the directions indicated by the arrow Z. The detector controller 100 controls the solid-state detector 30 to store a radiographic image converted thereby from the radiation 24 into the image information storage unit 102. Basic image capturing methods (a scout image capturing process and a stereographic image capturing process) for capturing a radiographic image to be stored in the image information storage unit 102 will be described below with reference to FIGS. 5 and 6. The mammographic apparatus 12 performs a scout image capturing process (see FIG. 5) in which the radiation source 26 disposed on the vertical axis (central axis 130a of the radiation source 26) of the solid-state detector 30 applies radiation 24a to the breast 22 or a stereographic image capturing process (see FIG. 6) in which the radiation source 26 disposed obliquely to the central axis 130a applies radiation 24b, 24c to the breast 22 along respective central axes 130b, 130c of the obliquely disposed radiation source 26. The solid-state detector 30 detects the radiation 24a, 24b, 24c that has passed through the breast 22 in the scout image capturing process or the stereographic image capturing process and converts the detected radiation 24a, 24b, 24c into respective radiographic images. In the mammographic apparatus 12, the radiation source 26 applies the radiation 24a, 24b, 24c to the breast 22 when the biopsy region 36 is located on the respective central axes 130a, 130b, 130c. FIG. 5 illustrates the scout image capturing process which captures a single radiographic image. In the scout image capturing process, the radiation source 26 is located at an image capturing angle of θ=0° with respect to the solid-state detector 30. The position of the radiation source 26 at the image capturing angle of θ=0° in the scout image capturing process is referred to as “position A”. FIG. 6 illustrates the stereographic image capturing process which captures two radiographic images. In the stereographic image capturing process, the radiation source 26 is located at two image capturing angles of +θ1, −θ1 with respect to the solid-state detector 30. The positions of the radiation source 26 at the image capturing angles of +θ1, −θ1 in the stereographic image capturing process are referred to as “position B” and “position C”, respectively. In FIG. 6, the irradiated range and irradiated field of the radiation 24b which is emitted from the radiation source 26 that is located in the position B at the image capturing angle of +θ1 are defined by an angle (radiating angle) θB1, and the irradiated range and irradiated field of the radiation 24c which is emitted from the radiation source 26 that is located in the position C at the image capturing angle of −θ1 are defined by an angle (radiating angle) θC1. The mammographic apparatus 12 may perform scout image capturing processes and stereographic image capturing processes according to any desired imaging sequence. The radiation source 26 is moved between the position A, the position B, the position C when the radiation source housing unit 28 is turned about the hinge 42. In the above stereographic image capturing process, the radiation source 26 applies the radiation 24b, 24c when it is located in the respective positions B, C. However, the mammographic apparatus 12 may perform a stereographic image capturing process in which the radiation source 26 applies the radiation 24a, 24b when it is located in the respective positions A, B, and/or a stereographic image capturing process in which the radiation source 26 applies the radiation 24a, 24c when it is located in the respective positions A, C. When the mammographic apparatus 12 performs a scout image capturing process, the image information storage unit 102 stores a single radiographic image captured at a single image capturing angle. When the mammographic apparatus 12 performs a stereographic image capturing process, the image information storage unit 102 stores two radiographic images captured at two respective image capturing angles (stereographic angles). In FIG. 4, the CAD processor 104 processes a radiographic image stored in the image information storage unit 102 and displays the processed radiographic image on the display unit 106 and the display control panel 40. The biopsy region selector 108 comprises a pointing device such as a mouse or the like. The doctor or radiological technician in charge who has seen the displayed contents, e.g., two radiographic images produced by a stereographic image capturing process, on the display unit 106 and/or the display control panel 40 can select one, from which a tissue is to be removed, of a plurality of biopsy regions 36 in the displayed two radiographic images, using the pointing device as the biopsy region selector 108. Specifically, the doctor or radiological technician selects a biopsy region 36 in one of the two radiographic images and also selects a corresponding biopsy region 36 in the other of the two radiographic images. The biopsy region positional information calculator 110 calculates the three-dimensional position of the selected biopsy region 36 based on the positions of the selected biopsy region 36 in the two radiographic images that are selected by the biopsy region selector 108. The three-dimensional position of the selected biopsy region 36 can be calculated according to a known three-dimensional position calculating scheme for the stereographic image capturing process. The biopsy needle positional information calculator 114 calculates the positional information of the tip end of the biopsy needle 56 which has been moved by the biopsy needle controller 112. When a tissue is to be sampled from the biopsy region 36, the biopsy needle positional information calculator 114 calculates the position of the tip end of the biopsy needle 56 before it samples the tissue from the biopsy region 36, i.e., the position of the tip end of the biopsy needle 56 before it pierces the breast 22. The compression plate positional information calculator 118 calculates the positional information of the compression plate 34 which has been moved with respect to the image capturing base 32 by the compression plate controller 116. Since the compression plate 34 presses the breast 22 with respect to the image capturing base 32 and holds the breast 22 in the pressed state, the positional information of the compression plate 34 represents the thickness information of the breast 22 as it is pressed. The traveled distance calculator 120 calculates the distance by which the biopsy needle 56 is to move with respect to the biopsy region 36, based on the three-dimensional position of the biopsy region 36 which has been calculated by the biopsy region positional information calculator 110, the position of the tip end of the biopsy needle 56 which has been calculated by the biopsy needle positional information calculator 114, and the position of the compression plate 34 which has been calculated by the compression plate positional information calculator 118 (the thickness of the breast 22). Based on the calculated distance by which the biopsy needle 56 is to move with respect to the biopsy region 36, the biopsy needle controller 112 moves the biopsy needle 56 for removing a tissue sample from the selected biopsy region 36. The image capturing selector 90 comprises a pointing device such as a mouse or the like or a keyboard. The doctor or radiological technician changes an image capturing method preset in the image capturing condition setting section 92 to another image capturing method, using the pointing device or the keyboard. Even after radiographic images have been captured, the doctor or radiological technician can select a radiographic image to be used by the biopsy region positional information calculator 110 to calculate the three-dimensional position, using the pointing device or the keyboard. The angle setting unit 122 comprises a pointing device such as a mouse or the like or a keyboard. The doctor or radiological technician sets image capturing angles and/or radiating angles for a stereographic image capturing process in the image capturing condition setting section 92, or changes the image capturing angles and/or radiating angles already set in the image capturing condition setting section 92, using the pointing device or the keyboard. The irradiated field calculator 126 reads the image capturing conditions for a stereographic image capturing process that have been set in the image capturing condition setting section 92, and calculates an irradiated field of the radiation 24 for a next stereographic image capturing process based on the read image capturing conditions and the three-dimensional position of the biopsy region 36 calculated by the biopsy region positional information calculator 110. In this case, the biopsy region positional information calculator 110 calculates the three-dimensional position of the biopsy region 36 in the previous stereographic image capturing process based on the two radiographic images captured in the previous stereographic image capturing process and stored in the image information storage unit 102, and outputs the calculated three-dimensional position to the irradiated field calculator 126. Therefore, the irradiated field calculator 126 reads the image capturing conditions for the previous stereographic image capturing process that have been set in the image capturing condition setting section 92. Specifically, the irradiated field calculator 126 calculates the irradiated range and irradiated field of the radiation 24 in a next stereographic image capturing process, i.e., the positions of the shield plates 70a through 70d (the position and area of the opening 82 through which the radiation 24 passes), such that the biopsy region 36 will be located on the central axes 130b, 130c and be included in the irradiated range of the radiation 24, using the three-dimensional positions of the radiation source 26 at the two image capturing angles, the positional information of the shield plates 70a through 70d in the previous stereographic image capturing process, and the three-dimensional position of the biopsy region 36 in the previous stereographic image capturing process, among the image capturing conditions of the previous stereographic image capturing process. Since the positional information of the shield plates 70a through 70d corresponds to the radiating angle, the irradiated field calculator 126 indirectly calculates the radiating angle which defines the irradiated field of the radiation 24 by calculating the positions of the shield plates 70a through 70d. The irradiated field calculator 126 sets the calculated positional information of the shield plates 70a through 70d as new image capturing conditions for a next stereographic image capturing process in the image capturing condition setting section 92, thus updating the setting contents of image capturing condition setting section 92. FIG. 7 shows, by way of example, irradiated ranges (broken lines) of the radiation 24b, 24c in a previous stereographic image capturing process and irradiated ranges (one-dot-and-dash lines) of the radiation 24b, 24c in a next stereographic image capturing process. In a stereographic image capturing process carried out by the mammographic apparatus 12, insofar as the biopsy region 36 is positioned within the irradiated ranges of the radiation 24b, 24c, the three-dimensional position of the biopsy region 36 can reliably be calculated based on the two radiographic images. According to the present embodiment, in order to avoid undue exposure of the examinee 20, i.e., the breast 22, to the radiation, the irradiated ranges of the radiation 24b, 24c for the next stereographic image capturing process (see FIG. 7) are made smaller than the irradiated ranges of the radiation 24b, 24c for the previous stereographic image capturing process, based on the results of the previous stereographic image capturing process (see FIG. 6), and then the next stereographic image capturing process is carried out. In other words, the radiating angles which define the irradiated ranges of the radiation 24b, 24c are changed from θB1, θC1 (the previous stereographic image capturing process) to θB2, θC2 (the next stereographic image capturing process) (θB1>θ2, θC1>θC2). As a result, the irradiated ranges of the radiation 24b, 24c are restricted from a range 132 (the previous stereographic image capturing process) to a range 134 (the next stereographic image capturing process) (see FIG. 8). In FIG. 4, the irradiated field calculation controller 124 comprises a pointing device such as a mouse or the like or a keyboard. The doctor or radiological technician can enable the irradiated field calculator 126 to carry out a calculating process for calculating an irradiated field of the radiation 24, i.e., can perform the calculating process, or can disable the irradiated field calculator 126, i.e., can stop the calculating process, using the pointing device of the keyboard. The mammographic apparatus 12 according to the present embodiment is basically constructed as described above. Operation of the mammographic apparatus 12 to perform a radiographic image capturing method according to the embodiment will be described below with reference to flowcharts shown in FIGS. 9 and 10. Before radiographic images are captured, image capturing conditions including a tube current and a tube voltage depending on the breast 22, an irradiation dose and an irradiation time of the radiation 24, an image capturing method, and an imaging sequence are set in the image capturing condition setting section 92. Image capturing angles and radiating angles are set by the angle setting unit 122, and the image capturing method is set by the image capturing selector 90. The doctor or radiological technician operates the irradiated field calculation controller 124 to disable the irradiated field calculator 126 to stop its processing function. In step S1, the doctor or radiological technician positions the breast 22 of the examinee 20. Specifically, the doctor or radiological technician places the breast 22 in a predetermined position on the image capturing base 32, i.e., a position facing the opening 48, and operates the compression plate controller 116 to move the compression plate 34 toward the image capturing base 32 in the direction indicated by the arrow Z, compressing and positioning the breast 22. The breast 22 is now compressed and secured by the image capturing base 32 and the compression plate 34. The compression plate positional information calculator 118 calculates the positional information of the compression plate 34 with respect to the image capturing base 32, and outputs the calculated positional information to the traveled distance calculator 120. After the above preparatory process is completed, the mammographic apparatus 12 energizes the radiation source 26 to perform a scout image capturing process on the breast 22 in step S2. Specifically, the radiation source housing unit 28 is turned about the hinge 42 (see FIG. 1) to move the radiation source 26 to the position A (see FIG. 5). Thereafter, the collimator controller 98 energizes the motors 76a through 76d (see FIG. 3) of the collimator 60 according to the image capturing conditions of the scout image capturing process from the image capturing condition setting section 92. The shield plates 70a through 70d are displaced to set the opening 82 to the position and area according to the image capturing conditions. Then, the light source controller 96 energizes the light source 62 to emit illuminating light. The emitted illuminating light is reflected by the mirror 64 toward the collimator 60 and passes through the opening 82 toward the breast 22. As a result, the illuminating light is applied to the compression plate 34 and so on, spotlighting the compression plate 34 to indicate the irradiated field of the radiation 24 (a light irradiated field) thereon. After having confirmed the light irradiated field, the doctor or radiological technician turns on an exposure switch, not shown. The radiation source controller 94 now energizes the radiation source 26 placed in the position A) (0°) according to the image capturing conditions from the image capturing condition getting section 92. The radiation 24 emitted from the radiation source 26 in the position A passes through the opening 82 out of the collimator 60, and is applied to the breast 22. The radiation 24 then passes through the breast 22, and is detected by the solid-state detector 30 as radiation representing a single radiographic image of the breast 22. The detector controller 100 controls the solid-state detector 30 to acquire a single radiographic image from the detected radiation and to store the acquired radiographic image in the image information storage unit 102. The CAD processor 104 processes the radiographic image stored in the image information storage unit 102, and displays the processed radiographic image on the display unit 106 and the display control panel 40. The doctor or radiological technician can now confirm that the breast 22 including the biopsy region 36 is positioned within a radiographic image capturing range. In step S3, the mammographic apparatus 12 energizes the radiation source 26 to perform a stereographic image capturing process on the breast 22. The mammographic apparatus 12 turns the radiation source housing unit 28 about the hinge 42 (see FIG. 1) to place the radiation source 26 in the position B (see FIG. 6), for example. Then, the collimator controller 98 energizes the motors 76a through 76d of the collimator 60 according to the image capturing conditions of the stereographic image capturing process from the image capturing condition setting section 92. The shield plates 70a through 70d are displaced to set the opening 82 to the position and area according to the image capturing conditions. Then, the light source controller 96 energizes the light source 62 to emit illuminating light. The emitted illuminating light is reflected by the mirror 64 toward the collimator 60 and passes through the opening 82 toward the breast 22. The illuminating light is applied to the compression plate 34 and the like, indicating a light irradiated field. After having confirmed the light irradiated field, the doctor or radiological technician turns on the exposure switch. The radiation source controller 94 now energizes the radiation source 26 placed in the position B (+θ1) according to the stereographic image capturing conditions from the image capturing condition setting section 92. The radiation 24b emitted from the radiation source 26 in the position B passes through the opening 82 out of the collimator 60, and is applied to the breast 22. The radiation 24b then passes through the breast 22, and is detected by the solid-state detector 30 as radiation representing a first radiographic image of the breast 22. The detector controller 100 controls the solid-state detector 30 to acquire a single radiographic image from the detected radiation and to store the acquired radiographic image as the first radiographic image in the image information storage unit 102 temporarily. After the single radiographic image has been captured based on the radiation emitted from the radiation source 26 in the position B, the mammographic apparatus 12 moves the radiation source 26 to the position C in FIG. 6, and captures a second radiographic image of the breast 22 based on the radiation from the radiation source 26 in the position C, in a similar manner to the image capturing process in the position B described above. The second radiographic image is acquired in the position C and stored in the image information storage unit 102. Thereafter, the CAD processor 104 processes the two radiographic images stored in the image information storage unit 102, and displays the processed radiographic images on the display unit 106 and the display control panel 40. In step S4, the doctor or radiological technician sees the two radiographic images displayed on the display unit 106 and/or the display control panel 40, and selects a biopsy region 36 from which a tissue is to be sampled, from the biopsy regions 36 in the displayed two radiographic images by using the biopsy region selector 108 which is a pointing device such as a mouse. Then, the biopsy region positional information calculator 110 calculates the three-dimensional position of the selected biopsy region 36, and displays the calculated three-dimensional position on the display unit 106 and the display control panel 40. In step S5, the doctor or radiological technician sterilizes and gives a local anesthesia to the breast 22 before the biopsy needle 56 pierces the breast 22. In step S6, the mammographic apparatus 12 performs a second stereographic image capturing process again on the breast 22 because the biopsy region 36 may be positionally displaced by the local anesthesia in step S5. FIG. 10 is a flowchart of an operation sequence of second and subsequent stereographic image capturing processes. In the second stereographic image capturing process in step S6, the doctor or radiological technician determines whether the irradiated field 132 of the radiation 24b, 24c is to be restricted to the irradiated field 134 or not in step S20 shown in FIG. 10. If in step S20 the biopsy region 36 is not largely positionally displaced by the local anesthesia and the doctor or radiological technician judges that the biopsy region 36 will be included in two radiographic images to be acquired even if the irradiated field 132 is restricted to the irradiated field 134 (step S20: YES), then the doctor or radiological technician operates the irradiated field calculation controller 124 to enable the irradiated field calculator 126 to perform its processing function. In step S21, the irradiated field calculator 126 reads the image capturing conditions for the previous stereographic image capturing process (the first stereographic image capturing process in step S3) which have been set in the image capturing condition setting section 92. In step S22, the irradiated field calculator 126 calculates the positions of the shield plates 70a through 70d corresponding to the restricted irradiated field 134 such that the biopsy region 36 will be located on the central axes 130b, 130c and be included in the irradiated range of the radiation 24, using the three-dimensional positions of the radiation source 26 at the two image capturing angles +θ1, −θ1, the positional information of the shield plates 70a through 70d in the previous stereographic image capturing process, and the three-dimensional position of the biopsy region 36 based on the radiographic image in the previous stereographic image capturing process, calculated in step S3, among the image capturing conditions of the previous stereographic image capturing process. The irradiated field calculator 126 sets the calculated positions of the shield plates 70a through 70d as new image capturing conditions of the second stereographic image capturing process in step S6 in the image capturing condition setting section 92, thereby updating the setting contents of image capturing condition setting section 92. In step S23, the mammographic apparatus 12 turns the radiation source housing unit 28 about the hinge 42 (see FIG. 1) to place the radiation source 26 in the position B (see FIG. 6). Then, the collimator controller 98 energizes the motors 76a through 76d of the collimator 60 according to the updated image capturing conditions from the image capturing condition setting section 92. The shield plates 70a through 70d are moved to the position represented by the new image capturing conditions, thus restricting the position and area of the opening 82 to a position and area corresponding to the restricted irradiated field 134. In step S24, the light source controller 96 energizes the light source 62 to emit illuminating light. The emitted illuminating light is reflected by the mirror 64 and passes through the opening 82 toward the breast 22. The illuminating light is applied to the compression plate 34 and the like, indicating a light irradiated field. At this time, the light irradiated field is limited to the size representing the irradiated field 134. In step S25, after having confirmed the light irradiated field, the doctor or radiological technician turns on the exposure switch. The radiation source controller 94 now energizes the radiation source 26 placed in the position B (+θ1) according to the new image capturing conditions from the image capturing condition setting section 92. The radiation 24b emitted from the radiation source 26 in the position B passes through the opening 82, and is applied to the breast 22. The radiation 24b then passes through the breast 22, and is detected by the solid-state detector 30 as radiation representing a first radiographic image of the breast 22. As the position and area of the opening 82 have been restricted according the new image capturing conditions, the irradiated range of the radiation 24b is restricted from the range indicated by the broken lines to the range indicated by the one-dot-and-dash lines, and hence the irradiated field is restricted from the irradiated field 132 to the irradiated field 134 which covers the biopsy region 36. The detector controller 100 controls the solid-state detector 30 to acquire a single radiographic image from the detected radiation and to store the acquired radiographic image as the first radiographic image in the image information storage unit 102 temporarily. Then, the mammographic apparatus 12 determines whether the second stereographic image capturing process has been completed or not in step S26. Since a second radiographic image based on the radiation from the radiation source 26 in the position C in FIG. 7 has not been captured though the radiographic image based on the radiation from the radiation source 26 in the position B has been captured (step S26: NO), the mammographic apparatus 12 moves the radiation source 26 to the position C and captures a second radiographic image based on the radiation 24c from the radiation source 26 in the position C by carrying out steps S23 through S25 again in a similar manner to the image capturing process in the position B. The second radiographic image is acquired and stored in the image information storage unit 102 (step S26: YES) in the position C temporarily. Thereafter, the CAD processor 104 processes the two radiographic images stored in the image information storage unit 102, and displays the processed radiographic images on the display unit 106 and the display control panel 40. The doctor or radiological technician sees the two radiographic images displayed on the display unit 106 and/or the display control panel 40, and operates the biopsy region selector 108 to selects once again the biopsy region 36 from which a tissue is to be sampled, from the biopsy regions 36 in the displayed two radiographic images. Then, the biopsy region positional information calculator 110 calculates the three-dimensional position of the selected biopsy region 36, and displays the calculated three-dimensional position on the display unit 106 and the display control panel 40. In step S20 in FIG. 10, if the biopsy region 36 is largely positionally displaced by the local anesthesia and the doctor or radiological technician judges that that the biopsy region 36 will possibly be not included in two radiographic images to be acquired if the irradiated field 132 is restricted to the irradiated field 134 (step S20: NO), then the doctor or radiological technician keeps the irradiated field calculator 126 disabled to its processing function. In and after step S23, the mammographic apparatus 12 performs a stereographic image capturing process under the same image capturing conditions (including the irradiated field 132) as with the stereographic image capturing process in step S3. In step S7, the doctor or radiological technician makes an incision in the surface of the breast 22 with a surgical knife at a position where the biopsy needle 56 is to be inserted, and then inserts the biopsy needle 56 through the incision into the breast 22. At this time, the doctor or radiological technician pushes the biopsy needle 56 until the tip end of the biopsy needle 56 reaches a position immediately short of the biopsy region 36 in the breast 22. In step S8, the mammographic apparatus 12 performs a stereographic image capturing process again in the same manner as the stereographic image capturing process in step S6, in order to confirm whether the biopsy needle 56 is inserted along a direction aligned with the biopsy region 36 or not. If the irradiated field is to be restricted (step S20: YES) in step S8, then positional information of the shield plates 70a through 70d in the stereographic image capturing process in step S8 is calculated using the image capturing conditions of the stereographic image capturing process in step S6 and the three-dimensional position of the biopsy region 36 based on the two radiographic images acquired in the stereographic image capturing process in step S6, in steps S21, S22. In step S23 and subsequent steps, the stereographic image capturing process is carried out according to the image capturing conditions including the calculated positional information. When the two radiographic images captured in the stereographic image capturing process in step S8 are displayed on the display unit 106 and the display control panel 40, the doctor or radiological technician operates the biopsy region selector 108 to selects once again the biopsy region 36 from which a tissue is to be sampled, from the biopsy regions 36 in the displayed two radiographic images in a similar manner to step S4. Then, the biopsy region positional information calculator 110 calculates the three-dimensional position of the selected biopsy region 36, and displays the calculated three-dimensional position on the display unit 106 and the display control panel 40 and outputs the calculated three-dimensional position to the traveled distance calculator 120. In step S9, the traveled distance calculator 120 calculates the distance by which the biopsy needle 56 is to move with respect to the biopsy region 36, based on the three-dimensional position of the biopsy region 36, the position of the tip end of the biopsy needle 56 which has been calculated by the biopsy needle positional information calculator 114, and the positional information of the compression plate 34 which has been calculated by the compression plate positional information calculator 118, and outputs the calculated distance to the biopsy needle controller 112. The biopsy needle controller 112 can now move the sampler 58 of the biopsy needle 56 to the biopsy region 36. In step S10, the mammographic apparatus 12 performs a stereographic image capturing process again in the same manner as the stereographic image capturing process in steps S6, S8 in order to confirm whether the position of the biopsy region 36 and the position and direction of the sampler 58 are in agreement with each other or not. If the irradiated field is to be restricted (step S20: YES), then positional information of the shield plates 70a through 70d in the stereographic image capturing process in step S10 is calculated using the image capturing conditions of the stereographic image capturing process in step S8 and the three-dimensional position of the biopsy region 36 based on the two radiographic images acquired in the stereographic image capturing process in step S8, in steps S21, S22. In step S23 and subsequent steps, the stereographic image capturing process is carried out according to the image capturing conditions including the calculated positional information. When the two radiographic images captured in the stereographic image capturing process in step S10 are displayed on the display unit 106 and the display control panel 40, the doctor or radiological technician can easily confirm from the displayed radiographic images whether the position of the biopsy region 36 and the position and direction of the sampler 58 are in agreement with each other or not. In step S11, the biopsy needle 56 starts to sample a tissue from the biopsy region 36 under suction. Thereafter, the sampled tissue is inspected by an inspecting apparatus, not shown, to check, for example, if the tissue is calcified or not in step S12. In step S13, the mammographic apparatus 12 performs a stereographic image capturing process again in the same manner as the stereographic image capturing process in steps S6, S8, S10 in order to confirm that the tissue has been sampled from the biopsy region 36. If the irradiated field is to be restricted (step S20: YES), then positional information of the shield plates 70a through 70d in the stereographic image capturing process in step S13 is calculated using the image capturing conditions of the stereographic image capturing process in step S10 and the three-dimensional position of the biopsy region 36 based on the two radiographic images acquired in the stereographic image capturing process in step S10, in steps S21, S22. In step S23 and subsequent steps, the stereographic image capturing process is carried out according to the image capturing conditions including the calculated positional information. When the two radiographic images captured in the stereographic image capturing process in step S13 are displayed on the display unit 106 and the display control panel 40, the doctor or radiological technician can easily confirm from the displayed radiographic images whether the tissue has been sampled from the biopsy region 36 or not. Thereafter, the biopsy needle 56 is moved in the direction indicated by the arrow Z to remove the biopsy needle 56 from the breast 22 in step S14. The operation sequence shown in FIG. 9 is now ended. After all the tissue has been sampled from the biopsy region 36, the position of the biopsy region 36 may not subsequently be confirmed. To provide against such a situation, a marker is inserted into the biopsy region 36 prior to step S14. Specifically, a marker made of stainless steel is inserted into the biopsy region 36 by the sampler 58 of the biopsy needle 56 in step S15. Thereafter, the mammographic apparatus 12 performs a scout image capturing process again in the same manner as the scout image capturing process in step S2 in order to confirm the inserted marker in step S16. The display unit 106 and the display control panel 40 display a single radiographic image acquired by the scout image capturing process, based on which the doctor or radiological technician can easily confirm the marker inserted in the biopsy region 36. After the marker has been confirmed, the biopsy needle 56 is removed from the breast 22 in step S14. As described above, the mammographic apparatus 12 according to the present embodiment calculates an irradiated field (new irradiated field) in a next (or present) stereographic image capturing process based on the three-dimensional position of the biopsy region 36 which is obtained in a present (or previous) stereographic image capturing process, and performs the next stereographic image capturing process with the new irradiated field. Since the new irradiated field around the biopsy region 36 is irradiated with the radiation 24 in the next stereographic image capturing process, the radiation 24 is prevented from being applied to body regions of the examinee 20 which have nothing to do with the calculation of the three-dimensional position of the biopsy region 36, and hence the examinee 20 is prevented from being unduly exposed to the radiation 24. Even if the breast 22 is moved or positionally or angularly changed between stereographic image capturing processes or the radiation source 26 disposed at two image capturing angles suffers angular errors, since a new irradiated field around the biopsy region 36 is irradiated with the radiation 24 in a next stereographic image capturing process, two radiographic images acquired in the next stereographic image capturing process reliably cover the biopsy region 36. Consequently, it is possible to perform a stereographic image capturing process on the biopsy region 36 and to accurately calculate the three-dimensional position of the biopsy region 36 regardless of a movement or positional or angular change of the breast 22 or angular errors of the radiation source 26. According to the present embodiment, therefore, the examinee 20 is prevented from being unduly exposed to the radiation 24, and a stereographic image capturing process is reliably performed on the biopsy region 36 in the breast 22 to accurately calculate the three-dimensional position of the biopsy region 36. If steps S20 through S26 are carried out in each of the stereographic image capturing processes in steps S6, S8, S10, S13, then the application of the radiation 24 to the breast 22 from the radiation source 26 at the two image capturing angles, the calculation of the three-dimensional position of the biopsy region 36 by the biopsy region positional information calculator 110, the calculation of a new irradiated field by the irradiated field calculator 126, and the changing of the present irradiated field to the new irradiated field by the collimator controller 98 are successively carried out repeatedly. Accordingly, the present stereographic image capturing process is performed while reflecting the result (the three-dimensional position of the biopsy region 36) of the previous stereographic image capturing process, and the next stereographic image capturing process is performed while reflecting the result of the present stereographic image capturing process. As a result, even if the breast 22 is moved or positionally or angularly changed between stereographic image capturing processes or the radiation source 26 disposed at two image capturing angles suffers angular errors, the radiation source 26 can apply the radiation 24 to the breast 22 within a new irradiated field around the biopsy region 36. In other words, the radiation source 26 applies the radiation 24 to the breast 22 while at the same time tracking the biopsy region 36. The irradiated field calculation controller 124 can selectively enables the irradiated field calculator 126 to calculate the new irradiated field or disables the irradiated field calculator 126 to stop calculating the new irradiated field. If any movement or positional or angular change of the breast 22 between stereographic image capturing processes is small (step S20: YES), then the irradiated field calculation controller 124 enables the irradiated field calculator 126 to calculate the new irradiated for thereby preventing the examinee 20 from being unduly exposed to the radiation. On the other hand, if the breast 22 is greatly moved or positionally or angularly changed between stereographic image capturing processes (step S20: NO), then the irradiated field calculation controller 124 disables the irradiated field calculator 126 to stop calculating the new irradiated field, and the radiation 24 is applied to the breast 22 in a wider irradiated field, for thereby allowing the biopsy region 36 to be reliably covered by a radiographic image. Before the radiation source 26 applies the radiation 24 to the breast 22, the light source 62 applies illuminating light to spotlight the breast 22 to indicate an irradiated field thereon. It is thus easy to confirm whether there exists any obstacle to a stereographic image capturing process between the radiation source 26 and the breast 22, before the stereographic image capturing process is carried out. As shown in FIGS. 6 and 7, the sizes of the irradiated fields 132, 134 remain the same at the positions B, C in the stereographic image capturing process. However, the sizes of the irradiated fields 132, 134 may be different at the positions B, C (in the left and right) in the stereographic image capturing process insofar as the biopsy region 36 is covered in the acquired radiographic images. The doctor or radiological technician may operate the angle setting unit 122 to set a radiating angle in the image capturing condition setting section 92, and the irradiated field calculator 126 may calculate the positional information of the shield plates 70a through 70d based on the radiating angle thus set. The radiating angle set by the doctor or radiological technician should preferably be an angle selected in view of angular errors of the radiation source 26. Although a certain preferred embodiment of the present invention has been shown and described in detail, it should be understood that various changes and modifications may be made therein without departing from the scope of the appended claims.
041994051	summary	This invention relates to a graphite side reflector in block form for gas-cooled high-temperature nuclear reactors. In all known gas-cooled high-temperature nuclear reactors, the side reflector surrounding the core is built of graphite blocks, which may be surrounded externally by carbon blocks and for which the most varied dimensions and shapes have already been proposed. A feature common to all proposals which may be considered for the building of side reflectors is that they consist of two mutually concentric shells of graphite and possibly carbon, each of which is assembled from graphite blocks, the size and form of those blocks which constitute the inner shell being different from, preferably smaller than, those of the blocks constituting the outer shell. In the AVR reactor, Julich, both cylindrical shells consist of superimposed rings built of blocks, the rings of the inner graphite cylinder being not only shallower but also formed of a larger number of smaller blocks than the rings of the outer carbon cylinder. The same is true for the THTR-300, Schmehausen, also to be operated with spherical fuel elements, the block form as such in this case being different from that of the blocks used in the AVR reactor and both shells being of graphite, the graphite being of better quality for the inner shell. In the other known nuclear reactors of the type of interest here, the side reflector also consists of two shells, adapted in their shape to one another, concentrically one inside the other and assembled of graphite blocks, these shells therefore possessing, in a radial directon at every point, one coaxially extending joint. The same applies to the Dragon reactor, Dorset, GB, to the still shut down nuclear reactor at Peach Bottom, USA, and to the nuclear reactor at Fort Saint Vrain, Colo., USA, described in its construction in "Nuclear Engineering International," December 1969, Vol. 14, Number 163, page 1074. From this literature source it is known that this reactor possesses a honeycomb construction in cross-section, the shape of the graphite blocks provided for the innermost of the two concentric side reflector shells being hexagonal to fit the fuel elements. In this way the result is attained that the inner part of the side reflector, so-called "side-reflector-hexagonal-elements," can be replaced together with the fuel elements, which is also true for the so-called "life-reflector" of the Dragon reactor. By contrast, the inner graphite cylinder of the reflectors of the first two named reactors--AVR and THTR-300--is designed for the life of the nuclear reactor, it being assumed that no replacement or repair will be necessary. This certainly results in simpler block shapes, but all known structures of graphite blocks suffer from the disadvantage, consequent upon the different shape and larger number of blocks of the inner shell as compared with the outer shell, that considerable manufacturing costs are associated with these differences and also the difficulty and expense of constructing the inner shell is considerably greater than that for constructing the outer side reflector shell, which also has a supporting and stability function. A further quite considerable disadvantage, hitherto accepted as unavoidable, of the known side reflector construction consists in the fact that the vertical joint extending around between the two side reflector shells leads to thermodynamic conditions which imply especially high temperature excursions for the blocks of the inner shell, which consequently must be adapted in size and shape to avoid stress cracks or similar destructive phenomena arising from the superimposed radiation influences. This is especially true also for the AVR and THTR-300, since a replacement of the inner shell of the side reflector in a pebble-bed reactor would render a special apparatus necessary for this purpose alone, quite apart from the fact that replacement would be scarcely acceptable economically, since for this purpose the core would need to be emptied. The problem underlying the present invention is to create a side reflector of the type initially referred to, which is appreciably more simply constituted in its construction than previous known proposals but nevertheless does not render necessary an exchange or replacement of the blocks during the entire life of the reactor. In accordance with the invention, in a graphite side reflector for a gas-cooled high-temperature nuclear reactor, the reflector comprises a wall built up from blocks which extend radially continuously through the entire reflector wall thickness and recesses are provided in the inner end faces of at least those blocks which are arranged to be disposed in the upper region of the reactor core. This form of blocks produces considerable advantage in many respects. Thus, an appreciable saving in time and expense both in the manufacture of the blocks and also in assembling them to form a side reflector is associated with the integral construction of blocks extending through the entire reflector wall thickness. The omission of the aforementioned separating layer extending between the outer and inner shells of the side reflector results in thermodynamically more favourable conditions, which in a surprising manner afford the possibility of utilising the entire graphite material of the side reflector effectively for operation and incorporating it into shutdown processes, in that, in the case of a reactor shutdown, an undisturbed heat transfer can now spread the so-called shutdown heat, which is the concern of our German patent application P 25 16 123 and British patent application No. 13286/76, through the entire reflector volume, so that if the forced cooling of the reactor core should fail the heat flow into the side reflector can take place undisturbed in the radial direction. This results in a surprisingly simple and inherent utilisation of the properties of the graphite, which has the consequence, amongst other things, that for example the time available from the commencement of a fault situation until the intervention of the necessary emergency measures is increased. By the recesses provided in the inner end faces of the blocks, a completely novel concept for the construction of the side reflectors is offered, in that the initially mentioned differing sizes for the two types of blocks (for the inner and outer shells of the reflector) are no longer required, since in shaping the blocks, especially in regard to the size of the blocks, it is no longer necessary to take into account thermal influences leading to damage and destruction of the blocks. It is well known that the moderating of the fast neutrons leads to damage of the graphite structure, which is associated with a volumetric change of the graphite, which manifests itself, amongst other things depending upon the neutron influence, in a greater or lesser shrinkage or growth of the graphite. The resultant stresses have superimposed upon the the stresses which fluctuate with the particular operating condition, originating from thermal strains due to operational temperature changes, and lead in particular in the inner region of the reflector to overall loading or stressing of the graphite which is very difficult to monitor and detect, and which acts predominantly tangentially and axially to the reactor core, because there is little to impede contraction or expansion of the graphite in the radial direction. As a result of the recesses formed on the inner faces, the aforementioned geometrical changes are not prevented, so that the stress cracks which would otherwise occur and which hitherto could only be counteracted by the double-shell construction comprising blocks with substantially smaller inner end faces for the inner shell, are reliably avoided for the entire working life of the nuclear reactor. The stresses are thereby reduced to such an extent that the side reflector blocks possess a service life which reliably exceeds the working life of the reactor. The through construction of the comparatively large-volume graphite blocks finally has the additional advantage that the relative movements, caused in the known constructions by thermal effects, of the smaller blocks intended for the inner shell, are substantially reduced relatively to one another and relatively to the large, outer blocks are avoided. The thermal movements can indeed result in the smaller blocks in the inner shell becoming skewed, since the relatively large number of vertical rows of spacings, when summated, can lead to orders of magnitude which permit such a change of position and in particular, in those for the types of reactor which are charged with spherical fuel elements, render a falling out of the wedge-shaped blocks at least in the upper part, that is to say just above the surface of the pebble-bed forming part of the highest loaded region, at least to appear conceivable. In an advantageous construction, the recesses consist of sets of slits, preferably of a pattern of vertically and horizontally extending, sets of rectilinear slits. This form of the recesses is preferred in that the slits can be made extraordinarily simply, for example can be sawn in the blocks. Although the spacing between slits is not critical, the higher the neutron flux, the smaller this spacing is made, in order thereby to counteract the higher stresses associated with higher neutron flux levels. The invention is therefore, based upon the concept of simulating comparatively small block dimensions in that region of the blocks which is subjected to especially high stresses by neutron irradiation and thermal influence, as a result of which, as already mentioned, the provision of a substantially larger number of smaller blocks, which are more expensive to make and more time consuming and difficult to install, is dispensed with. In order still further to facilitate manufacture, the slits of each set are preferably at equal distances one from another. For the two mutually crossing sets of slits, the distances between slits in each can moreover be chosen to be identical, that is to say not only are the spacings between all horizontal slits equal, but also this dimension is the same as the spacing between the vertical slits. One especially advantageous construction is obtained, if the width and/or depth of the vertical slits is greater than that of the horizontal slits. The result of this is that, in that reflector region which is especially intensively heated by the gamma flux and neutron scatter, a by-pass flow of coolant gas to the reactor core is produced, which will completely cool this region in operation. It is sufficient to provide this differing width and depth construction only in the upper region of the core, that is over a length of about 40 to 50% of the total core height. This then constrains the by-pass flow to turn back into the reactor core and to become mixed with the hotter gas. The arrangement of slits in the end faces of the blocks disposed in the lower, remaining region of the core may be superfluous in certain reactor designs, for example when in a once-through charging method, the neutron flux is considerably reduced in this region. The aforementioned by-pass cooling during operation is also of importance because as a result, the temperature difference between the hot central zone of the reactor core and the inner face of the reflector is increased and, if the forced cooling should fail but full pressure of the coolant to be retained, a more powerful natural convection inside the reactor core will take place. The gas in the hot central zone then ascends and enters the free space between the surface of the pebble-bed and the top reflector. Here, it will flow radially towards the inner face of the side reflector and, giving up its heat to the reflector, will flow vertically downwards and then radially inwards and finally, becoming again heated up, will ascend into the hot central zone. In this connection it should be mentioned that, if the side reflector should be heated up only by thermal radiation, that is if the cooling should fail with loss of coolant gas, the influence of the temperature manifests itself in the difference of the fourth powers of the temperatures, and here therefore the proposals according to the present invention have an especially advantageous effect. As already mentioned, the slit width is not a critical parameter, but in nuclear reactors operating with spherical fuel elements, it should be smaller than the diameter of the fuel elements, so that these elements cannot jam in the slits. It is well known that, for various reasons, in nuclear reactors operating with spherical elements, the objective is not to allow the heap of spheres to reach its maximum packing density. A geometrically uniform packing of spheres is accompanied by disadvantages, which do not need to be discussed in detail here, and has hitherto been prevented by various measures, including for example the choice of differing diameters for the spherical fuel elements or even additional structures to produce an irregular reflector inner face. Within the scope of this invention, there is an especially simple possible way of achieving this end, namely by superimposing a discontinuity pattern upon the sets of slits, this discontinuity pattern being preferably produced by forming one discontinuity on the inner face of each block in the form of a truncated conical depression having a depth less than that of the slits. If the width of slit is suitably chosen, discontinuities are unnecessary. It has been found in investigations for determining the temperature distribution in the shielding layers of a high temperature nuclear reactor, carried out on the AVR experimental nuclear power plant, that the specific volumetric thermal power from the absorption of gamma radiation falls to 35% in the first 50 mm, and the thermal power from neutron radiation falls by one order of magnitude in the first 200 mm. The last-mentioned depth of penetration therefore in a certain sense constitutes the upper limit of the necessary extent of the slits in the radial direction. In the interests of simplifying production and reducing costs, a slit depth of 20 mm can, however, be regarded as sufficient, since if the permissible stress in the tangential and/or axial direction is exceeded at the base of a slit, both the plane of cracking and also the direction of cracking are predetermined. The invention leads in a surprising manner to ensuring the service life of the reflector without any replacement beyond the expected working life of the nuclear reactor, so that the blocks can be anchored securely and permanently in their relative positions, because they are of larger volume and there is no longer any need to allow for the possibility of replacement. Moreover, the cost of manufacture and erection of the side reflector is reduced, and the heat absorption of the reflector in hypothetical fault cases is increased and consequently the operating of the reactor in these cases is simplified, since in the reactor core the time needed for reaching the maximum final temperature is prolonged and the maximum end temperature itself is lowered.
	description	Hereinbelow, an embodiment of a boiling water type nuclear reactor use control rod according to the present invention will be explained with reference to the drawings. The present control rod is what is inserted into a reactor core in a boiling water type nuclear reactor and controls an output of the nuclear reactor. FIG. 1 is a schematic structural diagram of the present control rod of which center portion in its axial direction is omitted. FIG. 2 is a view taken along an arrowed line axe2x80x94a in FIG. 1, which shows a condition in which the present control rod inserted between fuel channel boxes. As shown in FIG. 1, a control rod 1 is configured in a substantially cross shape in its cross section (cross section perpendicular to the axial direction) and includes four blades 6 extending in four directions from the axial center (center axis). A handle 5 made of stainless steel is disposed at the upper ends of the blades 6 and a dropping speed limiter 2 is disposed at the lower ends of the blades 6. Each of the blades 6 is constituted by a substantially U shaped sheath 6a of which both ends are attached to a tie rod 4 made of stainless steel disposed at the axial center of the control rod 1 and neutron absorption rods (neutron absorbers) 3 arranged inside the sheath 6a. Each of the blades 6 is provided with many number of openings 6b on the side face thereof, and through these openings 6b it is designed that cooling water flows within the blades 6. The tie rod 4 is also configured to have a substantially cross shape in its cross section. A handle 5 is attached to the upper portion of the tie rod 4 by welding and a lower supporting plate 2 is also attached to the lower portion of the tie rod 4 by welding. The upper end portions of the sheathes 6a are fitted to the lower portion of the handle 5 and are attached thereto by welding. The lower end portions of the sheathes 6a are also fitted to the upper portion of the lower portion supporting plate 2 and are attached thereto by welding. The neutron absorption rods 3 are arranged in one line in a region between the handle 5 and the lower portion supporting plate 2 as well as in a region inside respective sheathes 6a and are held therein. As a material for the sheathes 6a such as stainless steel (SUS 304, SUS 316L) is used. The neutron absorption rods 3 are primarily for absorbing thermal neutrons in the reactor core and a material therefor such as B4C and Hf is used. As shown in FIG. 2, the control rod 1 is inserted into fuel channel boxes 7 and the amount of insertion thereof is required to be adjusted depending on respective conditions of starting, operating and stopping of the nuclear reactor. Namely, the control rod 1 is required to be moved in its axial direction. In order to assist the movement of the control rod 1 in its axial direction, each of four wing portions constituting the handle 5 is provided with a guide use roller (a sliding structural body) and the dropping speed limiter 2 is also provided with the guide use rollers at four positions around the circumference thereof. Rollers 8 as shown in FIG. 2 are a part of the constitutional elements of the guide use roller. FIG. 2 shows a state where the rollers 8 at the handle 5 contact on the outer surfaces of square cylindrical fuel channel boxes 7. Through the provision of such rollers 8, the control rod 1 can be easily moved without damaging the control rod 1 and the fuel channel boxes 7. For the sake of simplicity, fuel rods in the fuel channel boxes 7 and a part of the neutron absorption rods 3 in the sheathes 6a are omitted from FIG. 2. Now, a detailed structure of and near the guide use roller for the handle 5 in the first embodiment according to the present invention will be explained with reference to FIGS. 3A through 3D. FIG. 3A is a view seen along an arrow X in FIG. 1, FIG. 3B is a view seen along an arrow Y in FIG. 1, FIG. 3C is a cross sectional view taken along lines bxe2x80x94b in FIG. 3B and FIG. 3D is a cross sectional view taken along lines cxe2x80x94c in FIG. 3A. As shown in FIG. 3B, a circular hole 8a is provided at the side face of the handle 5 and a roller 8 is disposed in the circular hole 8a so as to permit rotation around a pin 9. The pin 9 is disposed in a direction perpendicular to the axial direction of the control rod 1 so that the rotating direction (vertical direction in FIG. 3B) of the roller 8 coincides with the movement direction (axial direction) of the control rod 1. As shown in FIG. 3D, the left end portion of the pin 9 is secured to the handle 5 by welding, numeral 15 in FIG. 3D shows the welding portion of the pin 9. As shown in FIG. 3C, at the upper portion and the lower portion of a pin hole 12 where the pin 9 is inserted grooves 10 are provided. Namely, the two grooves 10 are disposed at the upstream side and the downstream side in the axial direction of the control rod 1 as well as adjacent to a clearance between the pin 9 and the pin hole 12. In other words, two grooves 10 are communicated to the clearance at the upstream side and the downstream side of the clearance. As shown in FIG. 3D the grooves 10 are formed from the circular hole 8a near to the end of the pin 9. The guide use roller (sliding structural body) is constituted by the pin 9, the pin hole 12 and the roller 8. As methods of forming the grooves 10 at the handle 5, such as electric discharge machining, drilling and end milling can be used. When performing electric discharge machining, a finishing is required to suppress generation of microcracks. When performing drilling, if size of the grooves 10 is small, the processing of the pin hole can be performed after processing the pin, however, if the size of the groove is large and the groove is processed first, it becomes difficult to ensure a positional accuracy of the pin hole. Further, if the pin hole is processed first, it becomes difficult to ensure a size accuracy of the groove, because the drill escapes toward the pin hole. Accordingly, when the groove is large, it is preferable to process the pin hole first and then to process the groove little by little with an end mill. When the control rod 1 is set in the nuclear reactor, the cooling water flows in the axial direction (in vertical direction in. FIGS. 3C and 3D) of the control rod 1. Accordingly, through the provision of the two grooves 10 as shown in FIGS. 3C and 3D, a water flow 16 as shown in FIG. 3D is positively induced. Namely, the grooves 10 include a function of causing water flow in the clearance between the pin 9 and the pin hole 12 (a function of promoting water flow in the clearance). In this instance, water entering into the clearance from the lower portion of the space between the roller 8 and the circular hole 8a flows out via the grooves 10 to the upper portion of the space between the roller 8 and the circular hole 8a. Through the provision of the grooves 10 which form cooling water passages as has been explained at the upper portion and the lower portion of the pin hole 12, water in the clearance between the pin 9 and the pin hole 12 can be effectively exchanged. Accordingly, even if the stay interval of the control rod 1 in the nuclear reactor is prolonged, the corrosive environment at the clearance portion around the pin 9 can be surely improved. Thereby, the soundness of the control rod is enhanced and reliability thereof can be enhanced. Further, with the portions in the clearance portion where no grooves 10 are provided, since the pin 9 is positioned by the pin holes 12 at a predetermined position, the sliding function of the control rod 1 by the guide use roller can be maintained. Now, a preferable size of the groove 10 will be explained. FIG. 4 shows an example of corrosion test results performed by varying cooling water flow rate under a condition where the pin 9 is disposed in the handle 5 of the control rod 1. The abscissa represents cooling water flow rate x around the control rod 1, and the ordinate represents mass increase amount y of the pin 9 in the corrosion test. A positive mass increase amount y implies that the mass of the pin 9 has increased due to corrosion product. Namely, mass increase amount y represents corrosion amount of the pin 9. The test conditions are as follows; the diameter of the pin 9 is 3.18 mm, the diameter of the pin hole 12 is 3.2 mm, the depth of the pin hole 12 L2=11 mm (see FIG. 3D), the temperature of the cooling water 288xc2x0 C., the desolved oxygen concentration in the cooling water is 3.2 ppm. The cross sectional configuration of the grooves 10 provided at the upper portion and at the lower portion of the pin hole 12 is width of 2 mmxc3x97depth of 1 mm. L1 in FIG. 3D is about 7.9 mm and for the cooling water temperature and the desolved oxygen concentration typical values in an actual nuclear reactor are used. Under the above conditions the corrosion test was performed for about 200 hours. In FIG. 4, symbol xcex94 shows data in the case of no grooves and symbol ∘ shows data in the case with grooves. In the case of no grooves, the clearance between the pin 9 and the pin hole 12 was 0.01 mm at one side thereof and the cross sectional area of the clearance was 0.1 mm2, of which clearance cross sectional area is comparable with the actual nuclear reactor. In the case with grooves the total cross sectional area of the clearance and of the grooves was 4.3 mm2. As shown in FIG. 4, in the case of no grooves, even when the cooling water flow rate x are varied, the mass increase amount y varies little and stays at 0.07 mg. On the other hand, in the case with grooves the mass increase amount y decreases depending on the increase of the cooling water flow rate x. In this instance, the relationship between the flow rate x and the mass increase amount y can be approximated by xcex2 (y=xe2x88x920.769x+0.07) as shown by a dotted line in FIG. 4. Namely, FIG. 4 shows that in the case of no grooves substantially no water flow exists in the clearance between the pin 9 and the pin holes 12, and in the case with grooves water flow exists in the clearance between the pin 9 and the pin hole 12. In the actual nuclear reactor, there exists water flow (flow rate: about more than 0.2 m/s.) directing from the bottom to the top between the control rod 1 and the fuel channel boxes 7. In order to keep the mass increase amount at 0 mg under the flow rate of 0.2 m/s, it is necessary to determine the negative variation rate of the mass increase amount y with respect to flow rate x (hereinafter referred to as corrosion decrease rate) at the negative value larger than xe2x88x920.35 mg/(m/s). Such border line xcex1(Y=xe2x88x920.350x+0.07) is shown by a solid line in FIG. 4. FIG. 5 is a determined result of a relationship between the above referred to corrosion decrease rate Z and clearance cross sectional area S. Herein, the clearance cross sectional area S represents a total sum of the cross sectional area of the clearance between the pin 9 and the pin hole 12 and the cross sectional area of the grooves 10. The relationship between corrosion decrease rate Z and clearance cross sectional area S can be approximated as Z=xe2x88x920.179S. In order to obtain a corrosion decrease rate more than xe2x88x920.35 mg/(m/s), it is understood from FIG. 5 that the clearance cross sectional area S has to be determined more than 1.96 mm2. In view of the clearance between the pin 9 and the pin hole 12 in an actual nuclear reactor is 0.01 mm (the clearance cross sectional area of 0.1 mm2), it is preferable to determine the cross sectional area of the grooves 10 to be more than 1.86 mm2. Now, another advantage achieved by the provision of the grooves 10 at the pin hole 12 will be explained. In case when reactor water can not circulate, because of, for example, failure of a pump which causes to circulate water (reactor water) in a nuclear reactor, a corrosion possibly advances rapidly even with the structure including the grooves 10. In such instance, a possible corrosive product grows in the clearance between the pin 9 and the pin hole 12 and a force 13 which expands the handle 5 will be caused as shown in FIG. 6. Herein, FIG. 6 shows the same cross section as in FIG. 3C but the roller 8 is omitted. In this instance, a position in the handle 5 where a cracking is generated is at portions 5a of which plate thickness is most thin and if a stress 14 acting on the portions 5a exceeds the tensile stress of the constitutional material of the handle 5, it is believed that a cracking will be generated. However, through the provision of the grooves 10 at the pin hole 12 according to the present embodiment, the handle 5 can be easily deformable by the force 13 when subjected to the above referred to phenomenon. Therefore, the stress 14 acting on the portions 5a is reduced small in comparison with when no grooves 10 are provided. Namely, even if a corrosion is caused in the clearance between the pin 9 and the pin hole 12, the stress 14 acting on the portions 5a can be reduced, thereby, a possible generation of a stress corrosion cracking at the handle 5 can be suppressed. The total cross sectional area of 4.3 mm2 as explained in connection with FIG. 4 is a preferable value determined in view of a possible stress 14 generated by a corrosion caused by a pump failure circulating the reactor water as well as a possible loading applied at the time of earthquake. A preferable size of the grooves 10 corresponding to the above total cross sectional area is width of 2 mmxc3x97depth of 1 mm. Herein, the above discussion result depends on the fact that the pin hole depth L2 is 11 mm as in the actual nuclear reactor. If the pin hole depth L2 is shallower, the total cross sectional area (namely, cross sectional area of the grooves 10) can be reduced small corresponding to the shallowing ratio. Now, a detailed structure of and near the guide use roller for the handle 5 in the second embodiment according to the present invention will be explained with, reference to FIGS. 7A through 7D. FIG. 7A is a view seen along an arrow X in FIG. 1, FIG. 7B is a view seen along an arrow Y in FIG. 1, FIG. 7C is a cross sectional view taken along lines bxe2x80x94b in FIG. 7B and FIG. 7D is a cross sectional view taken along lines cxe2x80x94c in FIG. 7A. The present embodiment adds two elliptical holes 11 to the handle 5 of the control rod 1 according to the first embodiment. As shown in FIG. 7B, the elliptical holes 11 are provided at both end portions of the pin 9. Namely, one of the elliptical holes 11 is provided at the top end portion of the pin 9 (at the right end portion in FIG. 7B) and is communicated with the grooves 10 and the pin hole 12. The other elliptical hole 11 is provided adjacent the welded portion (at left end portion in FIG. 7B) 15 of the pin 9 and is also communicated with the grooves 10 and the pin hole 12. In the present embodiment too, the water flow 16 as shown by arrows in FIG. 7D can be positively induced, therefore, the same advantage as in the first embodiment can be obtained. Namely, even if a stay interval of the control rod 1 in the nuclear reactor is prolonged, the corrosive environment at the clearance portion around the pin 9 can be surely improved while maintaining the sliding function of the control rod by the guide use roller. Thereby, the soundness of the control rod is enhanced as well as the reliability thereof is also enhanced. In the present embodiment, since the elliptical holes 11 communicate with the grooves 10 and the pin hole 12, the water flow 16 can be effected more easily than in the first embodiment, which further enhances the advantage. Namely, the elliptical holes 11 possesses a function of promoting water flow in the grooves 10 and the pin hole 12. Further, as shown in FIG. 7D, other than the water flow 16 coming from the circular hole 8a another water flow 16a directly flowing in through the elliptical holes 11 exists. The water flow 16a through the elliptical holes 11 further promotes the water flow 16. By this action, the corrosive environment at the clearance portion around the pin 9 can be further improved. Further, in the first embodiment, since pin hole 12 is closed at the both ends of the pin 9, if a corrosion is induced due to failure of the pump circulating the reactor water, the stress 14 as explained in connection with FIG. 6 increases at the both end portions of the pin 9. However, in the present embodiment, since the elliptical holes 11 are provided at the both end portions of the pin 9, there are no portion 5a to which the stress 14 acts at the both end portions of the pin 9. Accordingly, even if a corrosion is caused at the clearance between the pin 9 and the pin hole 12 due to a failure of the pump, the stress 14 acting at portions near the clearance can be reduced, which also contributes to suppress a possible generation of stress corrosion cracking. Now, a detailed structure of and near the guide use roller for the handle 5 in the third embodiment according to the present invention will be explained with reference to FIGS. 8A through 8D. FIG. 8A is a view seen along an arrow X in FIG. 1, FIG. 8B is a view seen along an arrow Y in FIG. 1, FIG. 8C is a cross sectional view taken along lines bxe2x80x94b in FIG. 8B and FIG. 8D is a cross sectional view taken along lines cxe2x80x94c in FIG. 8A. In the present embodiment, grooves 10a are provided at the pin 9 instead of providing the grooves 10 at the handle 5 in the first embodiment. As shown in FIG. 8C, the grooves 10a are provided at the upper end portion and at the lower end portion of the pin 9. Namely, the two grooves 10a are disposed at the upstream side and at the downstream side in the axial direction of the control rod 1 as well as adjacent to the clearance between the pin 9 and the pin hole 12. As shown in FIG. 8D, the grooves 10a are formed from the circular hole 8a near to the portions of the pin 9. In the present embodiment too, the water flow 16 as shown by arrows in FIG. 8D can be positively induced, therefore, the same advantage as in the first embodiment can be obtained. Namely, even if a stay interval of the control rod 1 in the nuclear reactor is prolonged, the corrosive environment at the clearance portion around the pin 9 can be surely improved. Thereby, the soundness of the control rod is enhanced as well as the reliability thereof is also enhanced. Further, in the present embodiment, through the provision of the grooves 10a on the pin 9, the processing of the grooves 10a is facilitated in comparison with the first embodiment, thereby, the processing time of the control rod as well as the processing cost thereof are further reduced. Further, in the above embodiments, examples have been explained in which the grooves are provided around the pin in a guide use roller for the handle 5, however, when a like groove is provided around a pin in a guide use roller for a dropping speed limiter 2, the same advantages as explained above will be obtained. Further, as in the example shown in FIG. 9 when a like groove is provided around a pin in a guide use roller for a lower portion supporting plate 2a, the same advantages as explained above will be obtained. According to the present invention, even if the stay interval of the control rod in the nuclear reactor is prolonged, a corrosive environment at the clearance portion in the guide use, roller can be surely improved while maintaining the sliding function of the control rod by the guide use roller.
	abstract	According to one embodiment, a slit mechanism apparatus includes, two slit plates configured to adjust a thickness of X-rays, two slit link bars which are pivotally supported on two ends of each of the two slit plates to interlock the two slit plates, two shafts on which the two slit link bars are respectively mounted to rotate the two slit link bars, two shutter plates configured to block/pass the X-rays, and two shutter link bars which are pivotally supported on two ends of each of the two shutter plates to interlock the two shutter plates and are mounted on the two shafts together with the two slit link bars.
047217383	summary	BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to polymer compositions which include additives to increase the dielectric heating efficiency of said composition. In particular, the compositions of this invention include a polymer, e.g. a polymer substantially comprised of non-polar monomers, and an additive comprising a particulate, layered compound of a tetravalent atom and a pentavalent atom, selected from Group V of the Periodic Table of the Elements, and having an atomic weight of at least 30. The particulate, layered compounds may include organo radicals, to thereby enhance the compatibility of the particulate, layered compound and the polymer. In one aspect of this invention, the polymer compositions are thermoplastic molding compositions. In another aspect of this invention a method for molding thermoplastic molding compositions using microwave energy, in the radio frequency (RF) range of the microwave spectrum, is disclosed and claimed. In still another aspect of the invention thermoplastic molding compositions are sensitized so that energy of the microwave RF frequency can be used in the molding process. In yet another aspect the invention relates to objects molded of thermoplastic molding compositions. 2. Description of the Art It is known that microwave RF energy may be used to increase the temperature of polymer compositions comprising polar comonomers so that the temperature is raised above the softening point and molding and other thermoplastic shaping processes are possible. However, when the polymer is not comprised of polar comonomers, i.e. copolymers comprising nonpolar comonomers, polar additives must be incorporated therein to provide sensitivity to microwave RF energy. In general, polar compounds are substantially incompatible with the nonpolar hydrocarbon polymers such as polyethylene, polystyrene, polypropylene, etc. Providing microwave sensitivity e.g. RF sensitivity, to nonpolar polymers, in view of the incompatibility of nonpolar polymers, especially hydrocarbon polymers and polar additives, is thus a problem that has been sought to be solved. One solution to this problem has been the incorporation of asbestos in certain nonpolar polymers. Asbestos, however, is difficult to finely divide to the extent that it is uniformly dispersed throughout the polymer composition. In addition, asbestos is a material which has been associated with known health problems and thus it is not used in any application where it can be conveniently replaced. A clay-based product, sold under the Frequon.RTM. trademark, has been suggested as a substitute for asbestos. (Frequon.RTM. is marketed by Phillips Petroleum Company.) This material, while not having the health-related problems of asbestos does not have sufficient heat stability at temperatures greater than 350.degree. F. Thus, it would be desirable to have an additive which is compatible with nonpolar polymers and able to provide microwave, e.g. RF, sensitization to polymeric composites of the nonpolar polymer and the additive. It would also be desirable to have an additive which increases the dielectric heating efficiency across a relatively wide band of microwave radiation. SUMMARY OF THE INVENTION This invention provides polymer compositions which are sensitive to microwave radiation and comprise, in combination, a polymer, e.g. a nonpolar thermoplastic polymer, and an additive comprising a particulate layered compound Said additive comprises a tetravalent atom and a pentavalent atom, selected from Group V of the Periodic Table of the Elements, and having an atomic weight of at least 30. Preferably the tetravalent atom is bonded to an organo-radical, either directly, or through an oxygen atom. The organoradical(s) may be selected to enhance the compatibility of the particulate layered compound and enhance the absorption of microwave, e.g. radio frequency, or other radiation when blended with the polymer, e.g. a non-polar polymer. (The term microwave, for the purpose of the present invention, shall refer to that portion of the electro-magnetic spectrum having a frequency lower than the lowest wave length of the visible spectrum, i.e. a frequency lower than about 10.sup.14 Hz.) DETAILED DESCRIPTION OF THE INVENTION 1. The Additive The additive useful in preparing the microwave energy sensitive products of the instant invention will be selected from the group consisting of compounds represented by the formula M(O.sub.3 ZO.sub.x R).sub.n. In this formula n may equal 1 or 2, except that n is 1 when R is terminated by a tri- or tetra-oxy pentavalent atom. M represents a tetravalent atom selected from the group consisting of: ______________________________________ Zr Te Pr Mn V W Sn Pb Ir U Si Os Hf Ti Ru Nb Ge Th Pu Mo Ce ______________________________________ Z is an pentavalent atom selected from the group consisting of the members of Group V of the Periodic Table of the Elements having an atomic weight of at least 30; R is selected from the group consisting of hydrogen and organic radicals and x varies from 0 to 1. More preferably, said compound will be selected from the group consisting of the compounds represented by the general formula M(O.sub.3 PR).sub.2, or M(O.sub.3 POR).sub.2. The above compounds may be prepared by a process which comprises reacting, in a liquid medium, at least one acid compound, i.e. an organo-substituted, pentavalent atom containing acid, having the formula ((HO.sub.2 OZO.sub.x).sub.k R, wherein k is 1 when n is 2 and k is 2 when n is 1, with at least one of the above tetravalent metal ions to precipitate a solid in which the molar ratio of pentavalent atom to tetravalent atom is 2 to 1, the pentavalent atom is convalently bonded to R and when x equals 1, R is linked to the pentavalent element Z through oxygen. It should be noted that x will be 0 when the starting material for preparing the compound is represented by the general formula ##STR1## wherein n is 1 or 2, e.g., ##STR2## i.e., phosphorus acid or organophosphonic acids. When the starting material is represented by the general formula EQU ((HO).sub.2 Z--O).sub.n R; e.g., ((HO).sub.2 P--O).sub.n R, i.e., organophosphoric acids or phosphoric acid, x will be 1. If a mixture of such starting materials are used, x will vary from 0 to 1 in accordance with the ratio of the starting materials. The tetravalent atom M and the pentavalent atom Z, may be selected in accordance with the desired properties for the active moiety by those skilled in the art. However, M is preferably Zr or Ti and Z is preferably P. R is selected from the group consisting of hydrogen radicals, organo acyclic, alicyclic, heteroacyclic, heterocyclic, aromatic groups, and mixtures thereof. In one embodiment of this invention at least a portion of the R groups, are selected to enhance the compatibility of the layered compound in the nonpolar polymer. This selection may be conveniently be done by tailoring the layered compound, through the R groups, to obtain a solubility parameter substantially equal to the nonpolar polymer. This tailoring is similar to selecting a compatible plasticizer for the nonpolar polymer, and is within the skill of the art and should increase the dispersibility of the additive in the nonpolar polymer. At least some of the R groups are selected to provide polarity to the layered compound. The polar bonds in these R groups interact with the microwave energy to provide the heating thereof. Suitable polar bonds for such R groups include ##STR3## Thus, preferred R groups will include hydroxyl radicals, sulfhydryl radicals, nitrile, keto, halo, amino, etc. R is preferably chosen to enable the compound to achieve a layered structure. Thus, the size of the R may be important, since very bulky R groups may disrupt such layering. In general, with phosphorus as the pentavalent atom, the organo group will preferably occupy no more than about 24 .ANG..sup.2 for proper spacing. This preferable limitation is imposed by the basic crystal structure of zirconium phosphate. A spacing of 5.3 .ANG..sup.2 is known for the space bounded by zirconium atoms. It follows that any group anchored on each available site cannot have an area much larger than the site area and maintain a layered structure. This limitation can be avoided, however, through the use of a combination of larger and smaller groups, i.e., mixed components. If some of the sites are occupied by groups which have an area much less than about 24 .ANG..sup.2 adjacent groups can be larger than 24 .ANG..sup.2 and still maintain the layered structure of the compound. The cross-sectional area which will be occupied by a given organo group can be estimated in advance of actual compound preparation by the use of CPK space filling molecular models (Ealing Company) as follows: A model for the alkyl or aryl chain and terminal group is constructed, and it is situated on a scaled pattern of a hexagonal array with 5.3 .ANG. site distances. The area of the group is the projection area on this plane. Some areas which have been determined by this procedure are listed in Table 1. TABLE 1 ______________________________________ Minimum Area Minimum Area Moiety (.ANG..sup.2) Moiety (.ANG..sup.2) ______________________________________ Alkyl chain 15 Isopropyl 22.5 Phenyl 18 t-Butyl 25 Carboxyl 15 Chloromethyl 14 Sulfonate 24 Bromoethyl 17 Nitrile 9 Diphenyl- 50(approx) phosphino Morpholinomethyl 21 Mercaptoethyl 13.5 Trimethylamino 25 ______________________________________ Note that the bulk of the above described moieties must also be included when calculating the correct R group size for attaining the preferred layered structure for the additive. Note also the wide chemical variation of suitable R groups thus enabling ease of tailoring for the purpose of obtaining microwave (e.g. RF.) sensitivity as well as compatability with nonpolar thermoplastics. The most polar groups such as hydroxyl or mercapto are the most sensitive to microwave energy. Multiple polar groups in the sensitizer should increase sensitivity although intramolecular hydrogen bonding could decrease the overall response. Spectra of energy absorption can be taken to determine the optimum functional group for any microwave frequency of interest or for completely self contained systems, one can use a generator operating at the optimum frequency for energy absorption. However, maximum absorption response is not the main purpose of the sensitizer. The sensitizer must provide a controlled response which in an ideal situation decreases and levels off with increasing temperature. Examples of suitable layered compounds include: Zr(O.sub.3 PCH.sub.2 CH.sub.2 SH).sub.2 PA0 Zr(O.sub.3 PCH.sub.2 CH.sub.2 OH).sub.2 PA0 Zr(O.sub.3 PCH.sub.2 CH.sub.2 Cl).sub.2 PA0 Zr(O.sub.3 PCH2OH).sub.2 PA0 Zr(O.sub.3 POH).sub.2 PA0 Zr(O.sub.3 POCH.sub.2 CH.sub.2 OH).sub.2 PA0 Zr(O.sub.3 PCH.sub.2 CH.sub.2 CN).sub.2 PA0 Zr(O.sub.3 PC.sub.6 H.sub.4 OH).sub.2 PA0 Zr(O.sub.3 PCH.sub.2 CN).sub.2 PA0 Zr(O.sub.3 PC.sub.2 H.sub.4 NH.sub.2).sub.2 2. The Polymer The polymer may be a thermoplastic or a thermosetting polymer, comprised of polar or nonpolar monomers, or mixtures thereof. In one aspect of this invention the nonpolar polymer may be a nonpolar thermoplastic polymer, substantially comprised of nonpolar monomers, e.g. copolymerizable hydrocarbons, although copolymers having less than about 10 mole percent of polar monomers, e.g. vinylchloride, acrylonitrile, vinylidene chloride, vinylalcohol, etc., and the remainder nonpolar monomers, are for the purposes of this invention sufficiently nonpolar to be included as a nonpolar polymer. In another aspect of this invention polar polymers not containing the most microwave sensitive functional groups may be provided with increased useful sensitivity by incorporating one or more of the above-described additives. The preferred nonpolar polymers are comprised of copolymerized monomers selected from the group -olefins, polyenes (especially conjugated polyenes , and mixtures thereof. Examples of suitable - olefins include: ethylene, propylene, 1-butylene, styrene, -methylstyrene, etc. Suitable polyenes include: butadiene, 1, 3 hexadiene, cyclopentadiene, cyclohexadiene, etc. Thus the preferred nonpolar polymers are polyethylene, polystyrene, polypropylene, ethylene-propylene copolymer, terpolymers of ethylene, propylene and a polyene, styrene-butadiene copolymer, etc. The non-polar polymer useful in practicing this invention may be normally solid linear and radial teleblock thermoplastic elastomeric copolymers which characteristically exhibit high tensile strength and elongation in their natural condition, e.g., nonvulcanized state. Particularly suitable teleblock copolymers are copolymer elastomers derived from butadiene and styrene in which the butadiene to styrene ratio can vary from about 85:15 to about 45:55 parts by weight and which contain from about 10 to about 55 weight percent of the styrene incorporated as terminal polystyrene blocks. The amount of the thermoplastic polymer employed in blends preferably constitutes from about 30 to 100 weight percent of the total polymers utilized in preparing the compositions of this invention. Other thermoplastic polymers that may be employed in forming the compositions, that this invention comprises are generally solid resinous polymers of a vinyl-substituted aromatic compound, e.g., styrene, alpha-methyl styrene, etc., alone or copolymerized with a monomer such as a conjugated diene, e.g. butadiene. In general, the thermoplastic elastomers and other polymers described above are the non-polar thermoplastics for which the combination of components named below provide sensitizing for dielectric heating. Particularly preferred nonpolar polymers are polyethylene, including both high density and low density polyethylene, polypropylene, poly (butene-1) and copolymers including two or more of the monomers comprising said preferred nonpolar polymers. Other preferred polymers are polysulfones and polyesters. All of the above non-polar polymers may be used alone or in blends with other copolymers, including non-thermoplastic copolymers, such as elastomers, i.e. natural rubber, polybutadiene, styrene-butadiene rubber, Neoprene.RTM. rubber, etc. 3. The Polymer Composition The polymeric compositions of this invention may comprise a major portion of the polymer, e.g. a nonpolar polymer, and a minor portion of the additive. The specific amount of the additive is determined by the sensitivity of the selected additive to microwave radiation, the ease of heating of the selected polymer, and the desired temperature and rate of heating thereof that is required. Preferably the total amount of additive utilized in the polymer compositions of the present invention ranges from 0.5 to about 20 parts by weight per 100 parts by weight of the polymer composition and more preferably from about 1 to about 10 parts by weight for reasons of economy coupled with adequate response to microwave radiation. When it is desired to provide polymer compositions that are to be preheated by microwave radiation, e.g. RF radiation, prior to shaping, heating times employed are selected to achieve rapid softening of the compositions to moldable consistency without deleterious effects caused by local overheating. Generally, the heating times used can range from about 2 seconds to about 4 minutes. From a commercial standpoint, however, heating times ranging from about 4 to about 55 seconds are employed to obtain favorable production rates and this is a preferred range. On the other hand, the polymer compositions of this invention may be used to provide containers which enable heating of food or other materials contained therein by the heat generated by the interaction of microwave radiation and the container. (Containers useful for the microwave heating of food will include additives that are sensitive to microwave radiation greater than about 890 Mc/sec, e.g. 915 or 2450 Mc/sec, as opposed to polymer compositions which include the above additives for sensitization to microwave RF heating. Additives for RF heating will be selected for sensitivity to radiation in the range of 1 to 200 Mc/sec preferably 20 to 110 Mc/sec. For example, since high-frequency generators are commercially available having outputs of 100 KW at 30-40 Mc/sec and 25 KW at 100 Mc/sec additives that are sensitive to radiation at 30-40 Mc/sec and 100 Mc/sec are preferred if said additives are to be used in polymer composites that are to be preheated for compression or transfer molding processes.) Containers for microwave heating of food may be in the form of envelopes or pouches or cooking ware such as bowls, dishes etc. In this application, the amount of the additive would be selected to provide sufficient microwave sensitization to enable heating to an elevated temperature, e.g. a cooking temperature, but not to a temperature at which the integrity of the container is lost. Such application may require a lower amount of additive for example from 0.5 to about 5 parts by weight per 100 parts by weight of the polymer composition. In any event, one skilled in the art may select the proper amount of additive without undue experimentation, based on his needs. The polymer compositions of the instant invention may be prepared by techniques known in the art for preparing polymer compositions wherein a solid material is dispersed in a polymer. For example, rubber mills, sigma blade and Banbury mixers may be used to combine the particulate layered compound with the nonpolar polymer. The additive, in particulate form, may be preblended with particulized polymer, prior to processing for improved homogeneity of the resulting polymer composite. As noted above, the additive may be tailored to enhance the compatability thereof with the nonpolar polymer, therefore facile mixing is often found. Other components may be used as additives to the polymer compositions of the present invention and in preparation thereof including odorants, colorants and fillers, e.g., silica, clay, silicates, e.g., Wollastonite, calcium carbonate, glass beads and fibers, and the like. Plasticizing agents compatible with the nonpolar polymer can be employed if desired. Examples of these include naphthenic petroleum oils, e.g., ASTM type 104A, esters of adipic acid, phthalic acid, etc. Processing aids include the metal stearates, e.g., calcium stearate, zinc stearate, silicones, natural and synthetic waxes, and the like. Antioxidants and UV stabilizers can be added as desired from suitable commercially available materials. Exemplary of these include thiodipropionic esters, e.g., dilaurylthiodipropionate, hindered phenolic antioxidants, e.g. 2,6-di-t-butyl-4-methylphenol, octadecyl [3-(3,5-di-t-butyl-4-hydroxyphenyl)]propionate, thiodiethylene bis(3,5-di-t-butyl-4-hydroxy) hydrocinnamate, etc., and UV stabilizers such as 2(2"-hydroxy-5'-methylphenyl) benzotriazole, 2-hydroxy-4-n-octoxybenzophenone, [2,2'-thiobis(4-t-octyl-phenolato)]-n-butylamine-nickel(II), etc. Finally, resin filler coupling agents, blowing agents and curing agents for thermo setting materials may be included in the polymer composites of this invention. Generally the amounts of the various components in parts by weight per 100 parts by weight (php) thermoplastic elastomer will be as follows: filler, 10 to 600 php, plasticizing agent 0.1 to 90 php; antioxidant, 0.1 to 2 php, UV stabilizer, 0.1 to 3 php, coupling and blowing agents 0.01 to 10 php and thermoset curing agents 1 to 150 php. When the instant polymer compositions are to be shaped by microwave energy, e.g. RF energy, the molds employed are generally constructed from low cost, relatively low strength materials including silicone rubber, polysulfide rubber, polyurethane, plaster, cast aluminum, and the like. The nature of the mold is dependent upon the molding process used. If the invention composition is placed within the mold and the entire assembly is preheated by microwave energy, it is preferred that the mold used be made of a material such as silicone rubber that has a lower dielectric loss factor than the composition of the invention. It is within the scope of this invention to preheat the composition in a low dielectric loss container such as glass or ceramic and transfer it to a mold constructed from metals and the like for the actual shaping step. Generally, the composition is placed within a silicone rubber mold, the mold top is covered with a silicone sheet or a release paper, e.g., paper or the like covered with a release agent such as a silicone, and the assembly is placed between the plates of a high frequency electrical field which form a part of commercially available molding machines. The top plate is lowered to contact the release paper covering the mold and the composition is preheated by application of microwave energy for a desired length of time. After the preheating, sufficient pressure is employed to compression mold the composition e.g., about 10 to about 200 psig (68.9-1380 kPa), for a period of time generally ranging from about 0.1 to about 10 times the preheating time. The pressure is released, the assembly is preferably placed in a separate zone for cooling the mold and contents, after which the molded article is removed. A rotary table or the like containing a plurality of molds can be employed to provide molded parts at commercially attractive rates. Separation of the heating and cooling zones speeds production and reduces consumption of power. The following are specific examples of the instant invention. There is no intention that the scope of the instant invention be limited to the examples, since there are many variations thereon which are within the ordinary skill of the art.
053234316	abstract	A device for removably securing a reactor vessel washer to a reactor vessel stud for use in combination with a reactor vessel including a dome having a first flange positioned abutting a second flange of a reactor body, a plurality of reactor studs are disposed in both the first and second flanges and a nut and washer arrangement secured to the stud for rigidly attaching the dome to the body. The device comprises a retainer removably disposed on the stud and operable to mate the washer to the stud to maintain the positional relationship of the stud and washer as the stud is removed from the dome and the body.
	claims	1. A nuclear fission fuel structure for propagating a nuclear fission deflagration wave, the nuclear fission fuel structure comprising:a plurality of non-contiguous segments of previously-burned nuclear fission fuel material inserted into a core of a nuclear fission deflagration wave reactor; anda nuclear fission igniter module disposed in the core of the nuclear fission deflagration wave reactor to initiate a propagating nuclear fission deflagration wave in the previously-burned nuclear fission fuel material, the nuclear fission igniter module including a source of protons and an intermediate material configured to receive the protons from the source of protons and further configured to provide fast-fission neutrons to the previously-burned nuclear fission fuel material. 2. The nuclear fission fuel structure of claim 1, wherein the intermediate material provides the fast-fission neutrons by a process chosen from electro-fission of elements and photo-fission of elements. 3. The nuclear fission fuel structure of claim 1, wherein the source of protons includes a linear particle accelerator.
	abstract	A method of assisting recovery of an injury site of brain or spinal cord injury includes providing a therapeutic dose of X-ray radiation to the injury site through an array of parallel microplanar beams. The dose at least temporarily removes regeneration inhibitors from the irradiated regions. Substantially unirradiated cells surviving between the microplanar beams migrate to the in-beam irradiated portion and assist in recovery. The dose may be administered in dose fractions over several sessions, separated in time, using angle-variable intersecting microbeam arrays (AVIMA). Additional doses may be administered by varying the orientation of the microplanar beams. The method may be enhanced by injecting stem cells into the injury site.
051620944	abstract	An approach (10) is provided as a way of obtaining useful power from a fusion reaction utilizing light weight isotopes of hydrogen and helium. A potential well is created between two accelerating electrodes (26) that, in a vacuum, allows ions from sources (24) to be captured by the potential well. An axial magnetic field as created by solenoid (20) causes the captured ions to pass through an ion focusing region (22) and thus allowing fusion reactions to take place within the region. The magnetic field also confines the trajectory of the fusion products (18) to a series of helixes preventing them from reaching the solenoid walls, but instead forces them to exit the two ends of the solenoid. Useful power is obtained by allowing two heat exchangers to intercept the fusion ions and thereby allowing a coolant liquid to be heated as would be required to operate a steam turbogenerator. In a second embodiment the solenoid is shaped in a U configuration allowing the fusion products to exit the solenoid in essentially the same direction and thus derive useful thrust as would be required for spacecraft propulsion.
	claims	1. A power module assembly comprising:a reactor vessel that comprises a substantially sealed enclosure;a primary fluid coolant enclosed in the sealed enclosure of the reactor vessel;a reactor core located in a lower portion of the reactor vessel, the reactor core comprising a primary fluid coolant outlet near an upper end of the reactor core and a primary fluid coolant inlet near a lower end of the reactor core;a riser conduit that extends from near the top of the reactor core to an upper portion of the reactor vessel;a heat exchanger located about a portion of the riser conduit in the upper portion of the reactor vessel;a fluid bypass path defined between a lower end portion of the riser conduit and the upper end of the reactor core and substantially enclosed within the sealed enclosure of the reactor vessel between the primary fluid coolant outlet of the reactor core and the heat exchanger, the fluid bypass path hydraulically coupling a fluid coolant path that extends between the primary fluid coolant inlet of the reactor core and the primary fluid coolant outlet of the reactor core with an annulus between the riser conduit and the reactor vessel; anda flow restriction positioned within the fluid bypass path and between the lower end portion of the rise conduit and the upper end portion of the reactor core. 2. The power module assembly according to claim 1, wherein during a loss of coolant accident, the flow of primary coolant out of the upper portion of the riser conduit comprises steam, and wherein a flow of primary coolant through the fluid bypass path comprises a mixture of two-phase coolant. 3. The power module assembly according to claim 1, wherein the fluid bypass path is closed or reduced during a full power operation of the power module assembly. 4. The power module assembly according to claim 3, wherein the fluid bypass path is configured to open during a shut-down operation. 5. The power module assembly according to claim 4, wherein the shutdown operation comprises a loss of coolant accident or an over pressurization event. 6. The power module assembly according to claim 1, wherein a level of the primary coolant is above an outlet of the upper portion of the reactor vessel during full power operation, and wherein the level of primary coolant is below the outlet during a shut-down operation. 7. The power module assembly according to claim 6, wherein the level of the primary coolant remains above the fluid bypass path during the shut-down operation. 8. The power module assembly according to claim 1, wherein the flow restriction comprises a unidirectional valve that defines a flow path only from the fluid coolant path that extends between the primary fluid coolant inlet of the reactor core and the primary fluid coolant outlet of the reactor core to the annulus. 9. The power module assembly according to claim 1, wherein the flow restriction comprises one of:an always-open valve; ora modulating valve that comprises an actuator configured to adjust the modulating valve between an open position and a closed position. 10. A nuclear reactor module comprising:a reactor vessel that comprises a substantially sealed enclosure;a reactor housing mounted inside the reactor vessel, the reactor housing comprising a shroud and a riser located above the shroud within the sealed enclosure of the reactor vessel;a heat exchanger proximately located about the riser;a reactor core located in the shroud;a fluid bypass path defined between a lower end portion of the riser and an upper end portion of the shroud and substantially enclosed within the sealed enclosure of the reactor vessel between a fluid outlet of the shroud and the heat exchanger, the fluid bypass path hydraulically coupling a fluid coolant path that extends between a fluid inlet of the reactor core and the fluid outlet of the shroud with an annulus between the riser and the reactor vessel; anda flow restriction positioned within the fluid bypass path and between the lower end portion of the riser and the upper end portion of the shroud. 11. The nuclear reactor module according to claim 10, wherein an auxiliary flow of primary coolant exits the reactor housing due to a difference in hydrostatic forces in the fluid bypass path between the fluid coolant path that extends between the fluid inlet of the reactor core and the fluid outlet of the shroud and the annulus. 12. The nuclear reactor module according to claim 11, wherein the primary coolant exits the reactor housing as a result of a decrease in rate of the primary flow path of the primary coolant out of the riser. 13. The nuclear reactor module according to claim 10, wherein the fluid bypass path forms a passageway for coolant to exit the reactor housing during a loss of coolant accident or a depressurization event. 14. The nuclear reactor module according to claim 10, wherein the shroud comprises a nozzle-shaped member, the fluid outlet of the shroud being smaller than a fluid inlet of the shroud. 15. The nuclear reactor module according to claim 14, wherein the fluid inlet of the shroud is substantially the same size as a fluid outlet of the reactor core. 16. The nuclear reactor module according to claim 10, wherein the flow restriction comprises a unidirectional valve that defines a flow path only from the fluid coolant path that extends between the fluid inlet of the reactor core and the fluid outlet of the shroud to the annulus. 17. The nuclear reactor module according to claim 10, wherein the flow restriction comprises one of:an always-open valve; ora modulating valve that comprises an actuator configured to adjust the modulating valve between an open position and a closed position. 18. A nuclear reactor module comprising:a reactor vessel that comprises a substantially sealed enclosure;a reactor housing mounted inside the reactor vessel, the reactor housing comprising a shroud and a riser located above the shroud within the sealed enclosure of the reactor vessel;a heat exchanger proximately located about the riser;a reactor core located in the shroud; anda fluid bypass path defined between a lower end portion of the riser and an upper end portion of the shroud and substantially enclosed within the sealed enclosure of the reactor vessel between a fluid outlet of the shroud and the heat exchanger, the fluid bypass path hydraulically coupling a fluid coolant path that extends between a fluid inlet of the reactor core and the fluid outlet of the shroud with an annulus between the riser and the reactor vessel,wherein an auxiliary flow of primary coolant exits the reactor housing due to a difference in hydrostatic forces in the fluid bypass path between the fluid coolant path that extends between the fluid inlet of the reactor core and the fluid outlet of the shroud and the annulus. 19. The nuclear reactor module according to claim 18, wherein the shroud comprises a nozzle-shaped member, the fluid outlet of the shroud being smaller than a fluid inlet of the shroud, and the fluid inlet of the shroud is substantially the same size as a fluid outlet of the reactor core. 20. The nuclear reactor module according to claim 18, further comprising a flow restriction positioned within the fluid bypass path and between the lower end portion of the riser and the upper end portion of the shroud, the flow restriction comprising at least one of:a unidirectional valve that defines a flow path only from the fluid coolant path that extends between the fluid inlet of the reactor core and the fluid outlet of the shroud to the annulus;an always-open valve; ora modulating valve that comprises an actuator configured to adjust the modulating valve between an open position and a closed position. 21. A power module assembly comprising:a reactor vessel that comprises a substantially sealed enclosure;a primary fluid coolant enclosed in the sealed enclosure of the reactor vessel;a reactor core located in a lower portion of the reactor vessel, the reactor core comprising a primary fluid coolant outlet near an upper end of the reactor core and a primary fluid coolant inlet near a lower end of the reactor core;a riser conduit that extends from near the top of the reactor core to an upper portion of the reactor vessel;a heat exchanger located about a portion of the riser conduit in the upper portion of the reactor vessel; anda fluid bypass path defined between a lower end portion of the riser conduit and the upper end of the reactor core and substantially enclosed within the sealed enclosure of the reactor vessel between the primary fluid coolant outlet of the reactor core and the heat exchanger, the fluid bypass path hydraulically coupling a fluid coolant path that extends between the primary fluid coolant inlet of the reactor core and the primary fluid coolant outlet of the reactor core with an annulus between the riser conduit and the reactor vessel,wherein during a loss of coolant accident, the flow of primary coolant out of the upper portion of the riser conduit comprises steam, and wherein a flow of primary coolant through the fluid bypass path comprises a mixture of two-phase coolant. 22. A power module assembly comprising:a reactor vessel that comprises a substantially sealed enclosure;a primary fluid coolant enclosed in the sealed enclosure of the reactor vessel;a reactor core located in a lower portion of the reactor vessel, the reactor core comprising a primary fluid coolant outlet near an upper end of the reactor core and a primary fluid coolant inlet near a lower end of the reactor core;a riser conduit that extends from near the top of the reactor core to an upper portion of the reactor vessel;a heat exchanger located about a portion of the riser conduit in the upper portion of the reactor vessel; anda fluid bypass path defined between a lower end portion of the riser conduit and the upper end of the reactor core and substantially enclosed within the sealed enclosure of the reactor vessel between the primary fluid coolant outlet of the reactor core and the heat exchanger, the fluid bypass path hydraulically coupling a fluid coolant path that extends between the primary fluid coolant inlet of the reactor core and the primary fluid coolant outlet of the reactor core with an annulus between the riser conduit and the reactor vessel,wherein the fluid bypass path is closed or reduced during a full power operation of the power module assembly. 23. The power module assembly according to claim 22, wherein the fluid bypass path is configured to open during a shut-down operation, and the shutdown operation comprises a loss of coolant accident or an over pressurization event. 24. A power module assembly comprising:a reactor vessel that comprises a substantially sealed enclosure;a primary fluid coolant enclosed in the sealed enclosure of the reactor vessel;a reactor core located in a lower portion of the reactor vessel, the reactor core comprising a primary fluid coolant outlet near an upper end of the reactor core and a primary fluid coolant inlet near a lower end of the reactor core;a riser conduit that extends from near the top of the reactor core to an upper portion of the reactor vessel;a heat exchanger located about a portion of the riser conduit in the upper portion of the reactor vessel; anda fluid bypass path defined between a lower end portion of the riser conduit and the upper end of the reactor core and substantially enclosed within the sealed enclosure of the reactor vessel between the primary fluid coolant outlet of the reactor core and the heat exchanger, the fluid bypass path hydraulically coupling a fluid coolant path that extends between the primary fluid coolant inlet of the reactor core and the primary fluid coolant outlet of the reactor core with an annulus between the riser conduit and the reactor vessel,wherein a level of the primary coolant is above an outlet of the upper portion of the reactor vessel during full power operation, and wherein the level of primary coolant is below the outlet during a shut-down operation. 25. The power module assembly according to claim 24, wherein the level of the primary coolant remains above the fluid bypass path during the shut-down operation.
	description	This application is a 35 U.S.C. § 371 national phase application of PCT/GB2015/051872 (WO 2015/198069), filed on Jun. 26, 2015, entitled “Particle Beam Treatment” which application claims priority to United Kingdom Application No. 1411407.8, filed Jun. 26, 2014, which is incorporated herein by reference in its entirety. Field of the Invention The present invention relates to a method of treating a particle beam and to an apparatus for treating a particle beam. The invention has particular applicability for changing the charge state of particles in the particle beam. The invention has applications in various fields such as in accelerator mass spectrometry (AMS). The present invention also relates to a method of performing mass spectrometry and to a system for performing mass spectrometry. Ultrasensitive mass spectrometry (analysis techniques for determining sample constituents) can require the suppression of relatively large interferences to the intended measurement. Radiocarbon-dating is important to archaeology and earth-sciences, and radiocarbon-tracer measurement is important to earth- and life-sciences (especially pharmacology). Carbon is 98.9% stable 12C, 1.1% stable 13C and 10−12 (Modern) or less radioactive 14C; radiocarbon is anthropogenic and cosmogenic. Ubiquitous isobaric species such as 14N, 13CH and 12CH2 must typically be suppressed by many orders of magnitude to resolve 14C by mass spectrometry. This is achieved in conventional accelerator mass spectrometry (AMS) by separately suppressing 14N and the molecular species, as now explained. Firstly, atoms from the sample undergoing analysis are made negatively charged. As N− is only very short-lived, it is therefore removed. Subsequently the remaining ions, accelerated in a particle beam, with atomic/molecular mass 14 are collided with a ‘stripper’ that removes electrons and sufficiently breaks apart molecules prior to ion detection. AMS is an ultrasensitive method of mass spectrometry which utilizes techniques well-known in nuclear physics, typically for the quantification of naturally extremely rare long-lived radionuclides in samples undergoing element isotope ratio analysis. The applications of AMS are manifold and at the time of writing it is performed at approximately 100 centres worldwide which possess the expertise to operate the particle accelerators required. Sample production and preparation for these instruments is carried out at many more institutions. Synal (2013) (Hans-Arno Synal, Developments in accelerator mass spectrometry, International Journal of Mass Spectrometry 349-350 (2013) 192-202) and Kutschera (2013) (Walter Kutschera, Applications of accelerator mass spectrometry, International Journal of Mass Spectrometry 349-350 (2013) 203-218) are recent reviews of AMS. As explained in detail in Synal (2013) known AMS typically involves converting the prepared-sample atoms into negative ions and passing these through two mass spectrometers separated by a target that fully transmits only atoms with high kinetic energy, and registering the resulting ions in a final particle detector. For 14C AMS, for example, two stages of analysis are required: the first is to separate the ions of 14C from 14N atomic isobar interference, and the second is to prevent interference from molecular isobars, e.g. 13CH or 12CH2. Conventionally, negative ions are produced and analysed with the first mass spectrometer to remove the 14N interference, since N− ions produced unstable and therefore very short-lived. Molecular interference is overcome by subsequently colliding the negative ions with an inert gas or thin foil target and analysing the results with the second mass spectrometer and detector. There are variations on this theme but in all cases the negative ions must be sufficiently energized to be pass through the solid or gas ‘stripper’ target. In some known systems, the ion-stripper interaction aims to remove sufficient electrons to result in a charge state of 3+ or more. This large positive charge cannot be sustained by interfering molecular species, so molecular interference to radiocarbon ion detection is reduced by selecting for such a charge state with the subsequent mass spectrometer. In this case the ion-stripper interaction stimulates molecules to spontaneously dissociate. In more recent times, a method has been developed which is applicable at lower ion energies, involving the destruction of molecules directly by their interaction with the gas via repeated ion-gas molecule collision. This requires more stripper gas than then first case and this physics is called the ‘thick’-stripper technique. It is usual, but not essential for modest performance, to mount the stripper in the high-voltage terminal of an electrostatic particle accelerator as in U.S. Pat. No. 4,037,100, U.S. Pat. No. 5,661,299, and US2013/112869. Optionally the second mass spectrometer and particle detector can be accommodated in the terminal too, as described in U.S. Pat. No. 6,815,666. The present inventors have realised that the instruments and methods discussed above suffer from the significant limitations, difficulties and costs of operating the negative-ion sources employed to convert the sample into an ion beam. Typically, most of a sample measurement cost is in making the material to be analysed compatible with the ion source technology. Sputter ion sources produce negative ions from an evolving condensed-matter sample surface resulting in varying beam emittance and relatively small C− ion beams from carbon samples introduced as CO2 but larger beams when the CO2 is first additionally converted to graphite with greater carbon atom density. Also, sample repeat measurements are typically interleaved with measurements of other samples and standards materials to compensate for the emittance changes, meaning that after a sample measurement the remaining sample material must be recovered from the ion source and stored pending re-measurement. Such negative ion sources typically operate on difficult-to-control Cs metallic vapour in order to achieve their best, but still low, sample ionisation efficiency. In 1978, it was disclosed and appreciated that the usual AMS negative-to-positive atom charging arrangement might be reversed. This was disclosed in Middleton (1978) (see list of non-patent document references below for full details). The 3+ positive-to-negative alternative proposed by Middleton (1978) greatly reduced the need for a particle accelerator (beyond initial energization in the ion source to produce the ion beam) but the scheme first required ion source development. CA-A-2131942 specifies the use of an inductively coupled plasma ion source. In Hotchkis and Wei (2007) and Meyer et al (2009) (see also U.S. Pat. No. 6,455,844) measurement of radiocarbon-enriched materials is described using an electron cyclotron resonance (ECR) ion source combined, respectively, with negative ionisation in metallic vapour or by grazing incidence surface collision. The use of an ECR ion source in Roberts et al. (2007) whereby positive ions are immediately charge-exchanged negative and then subsequently stripped positive again is actually an example of the conventional AMS scheme, but indicates the elaboration pursued to compensate for the problems of the more normal negative sputter-ion sources employed. In Wilcken et al. (2010) and Wilcken et al. (2013) the previously-best but still insufficient measurement background for natural carbon analysis was achieved by using a thin solid membrane for negative ionisation. The present inventors have realised that thick-stripper physics also produces a useful amount of negative ions so that known metal vapour charge exchange cells can be improved upon whilst addressing several practical disadvantages of known metal vapour charge exchange cells, identified by the inventors. It has surprisingly been found that the adoption of thick-stripper physics and benign gases makes charge exchange cells additionally effective molecule suppressors without compromising negative ionisation efficiency at the level of suppression achieved. Furthermore, the creation, containment and metering of metal vapours is cumbersome, imprecise and difficult, typically requiring specialist equipment. Still further, metal vapours are electrically conducting if condensed and so pose a challenge when used in systems involving high electric fields such as mass spectrometers. The present invention has been devised in order to address at least one of the above problems. Preferably, the present invention reduces, ameliorates, avoids or overcomes at least one of the above problems. Accordingly, in a first preferred aspect, the present invention provides a method of treating a particle beam, the particle beam including positive ions, including the step of passing the particle beam through a charge exchange cell, the charge exchange cell containing a gaseous target material, the target material being a material that is electrically insulating at room temperature and pressure, at least some of the positive ions of the particle beam being converted to negative ions by interaction with the gaseous target material, the particle beam incident at the charge exchange cell further including molecules and/or molecular ions which interact with the gaseous target material to reduce the concentration of molecules as a result of repeated collisions with particles of the gaseous target material thereby to provide a treated particle beam. In a second preferred aspect, the present invention provides a method for performing mass spectrometry on an analyte sample including the steps of: generating a particle beam using the analyte sample, the particle beam including positive ions; passing the particle beam through a charge exchange cell according to the first aspect thereby to provide a treated particle beam containing negative ions; and passing the treated particle beam to a particle detector configured to detect at least some of said negative ions. In a third preferred aspect, the present invention provides a mass spectrometry system suitable for performing mass spectrometry on an analyte sample, the system including: a particle beam generator for generating a particle beam using the analyte sample, the particle beam including positive ions; a charge exchange cell, the charge exchange cell configurable to contain a gaseous target material, the target material being a material that is electrically insulating at room temperature and pressure, the charge exchange cell being operable so that at least some of the positive ions of the particle beam are converted to negative ions by interaction with the gaseous target material thereby to provide a treated particle beam; and a particle detector configured to detect at least some of said negative ions in said treated particle beam. The use in the charge exchange cell of a gas that is gaseous at about room temperature and atmospheric pressure is convenient because it allows the metering and manipulation of the gas using conventional gas handling equipment. In turn, this allows for precise control of the concentration and pressure of gas in the charge exchange cell. This also allows the use of precisely controlled mixtures of gases. The expression “gaseous target material” is used interchangeably in this disclosure with “target gas”. The gas employed in the charge exchange cell is of material that is electrically insulating at room temperature and pressure. The target material may not necessary be a gas at room temperature and pressure, but should be electrically insulating at room temperature and pressure irrespective of state. This is in contrast to known charge exchange cell gases which are typically metal vapours, which must be maintained at high temperature to remain in the gaseous state and so cannot be considered to be of materials that are electrically insulating at room temperature and pressure, under which conditions they would be condensed and electrically conductive. As indicated above, the generation and control of metal vapours is cumbersome and difficult. Furthermore, the use of high electric fields in mass spectrometry means that metal vapours must be carefully contained in order to avoid compromising the operation of the mass spectrometry system. The first, second and/or third aspect of the invention may be combined with each other in any combination. Furthermore, they may have any one or, to the extent that they are compatible, any combination of the following optional features. The gas used in the charge exchange cell preferably includes at least one of hydrogen, helium, nitrogen, argon, methane, ethane, propane, butane, isobutane, other hydrocarbons, or a mixture of two or more of these components. The inventors consider that these gases provide a suitable combination of ability to donate electrons to the positive ions in the ion beam and ability to destroy molecular interference. This relates particularly (but not exclusively) to the operation of the invention in the detection of 14C. It is also preferable that the target gas is energetically-pumped. This may be achieved using electromagnetic energy. It can be particularly suitable to pump the target gas using an RF or microwave signal. By energetically pumping the gas, the number of free electrons is increased (i.e. a full or partial plasma can be generated). As a result, the electron donation ability of the gas increases, and so it may be more effective as a negative-ion generator. The particle beam incident at the charge exchange cell includes molecules and/or molecular ions which interact with the target gas to reduce the concentration of molecules within the treated particle beam. The reduction in concentration occurs as a result of repeated collisions with gas atoms/molecules in the charge exchange cell. In order to effect efficient molecular suppression, the target gas should be sufficiently thick. In order to traverse the target gas, the incident ions in the particle beam should preferably have energies of at least 10 keV, more preferably at least 20 keV, more preferably at least 30 keV, more preferably at least 40 keV, more preferably at least 50 keV, more preferably at least 60 keV, more preferably at least 70 keV, more preferably at least 80 keV, more preferably at least 90 keV, and more preferably at least 100 keV. At these energies, the present inventors consider that non-metallic, electrically insulating gases are similarly efficient to metallic vapours but Hotchkis and Wei (2007), for example, failed to show that metallic vapours can act as both a good source of electrons and a good suppressor of molecules. Due to the benefits discussed above, insulating gases are therefore highly advantageous. Preferably, the target gas includes a mixture of gases. The amounts of each component in the target gas are preferably selected to favour the transmission of a particular particle species in the incident particle beam, while suppressing the transmission of others. For example, when it is desirable to transmit atomic carbon ions without prohibitively scattering them, but it is also desirable to eliminate hydrocarbon molecules from the treated beam, then size-matched nitrogen gas can be used or size-matched carbon atoms in gases of more complex molecules. Isobutane or propane can also be used, since these are highly electropositive, to promote the formation of negative carbon ions. Thus, preferably, the target gas preferably includes a component that is matched in terms of atomic weight to the species in the particle beam which it is intended to detect. A suitable or best match is established empirically but not being restricted to metals provides many more options for optimisation. Using the present invention, it is possible to adjust the components and/or concentration of the target gas in the charge exchange cell. This can be done readily and precisely using known mass flow gas controllers, for example. The required target gas formulation can be adjusted based on the detected negative ions and associated measurements. For example, in the case of 14C measurement, the formulation of the target gas can be adjusted while monitoring the measured 14C, stable carbon isotopes and their ratio. The optimum target gas thickness is the one which maximizes both the molecule suppression and charge exchange. Preferably, the composition and/or amount of gas in the charge exchange cell can be adjusted automatically using a feedback loop. Preferably, the incident particle beam is at least partially filtered before reaching the charge exchange cell. Unwanted constituents in the incident particle beam can thereby be removed. This facilitates the subsequent utilisation of the remaining species including their identification and/or quantification. For example, when used in radiocarbon detection, it is preferable that the incident beam constituents include at least one of 14C+, 14C2+, 14C3+. This is controlled by the ion source. Certain ion sources, as set out later, are advantageous in that they can play a role in suppressing interfering species. However, usually interfering species will be present in the particle beam generated from the ion source. Filtration of the particle beam before arrival at the charge exchange call can remove at least some species. Preferably, the incident particle beam is filtered so that it consists primarily of 14C2+. This is considered to provide technical advantages over selection of 14C1+ or 14C3+. Selection of the 1+ charge-state is considered to produce super-natural measurement background, and selection of 3+ charge-state ions is more challenging, since they are more difficult to produce, require higher energy ion sources and in any event are less abundantly produced and so provide a low signal. This filtering is preferably carried out using a first mass spectrometer between the ion source and the charge exchange cell. However it should be noted that this filtering step is not considered essential. Further filtering of the particle beam, for example to filter out undesirable negative ion species (for example, leaving substantially only 14C−), is preferably carried out after the beam leaves the charge exchange cell, and before the beam reaches the detector. The positive ions in the particle beam are preferably generated using an electron cyclotron resonance (ECR) ion source. Plasma ion sources such as ECR ion sources can produce intense positive ion beams from gas samples as the ions are extracted from the sample volume, in contrast with AMS sputter ion source sample surface ionisation. ECR ion sources can readily achieve reliable operating conditions, and are more compatible with common analytical chemistry automated sample specification and preparation techniques. The plasma in the ECR ion source is preferably manipulated, for example by the addition of a carrier gas or by addition of excess sample material, in order that the ECR ion source operates to discriminate against the production of ions of some constituents. For example, a helium carrier gas can suppress the production of hydrocarbon molecules which are potential interferences to carbon atomic ions in the case of a CO2 sample. Thus, it is preferred that following generation of the particle beam, a portion of the particle beam is selected using a first mass spectrometer, prior to reaching the charge exchange cell. In the charge exchange cell, preferably the target gas suppresses at least one interfering species by repeated collision with the target gas. Following the charge exchange cell, preferably the treated particle beam is further subjected to selection using a second mass spectrometer. Following this, preferably the selected part of the treated particle beam reaches the particle detector configured to detect at least some of said negative ions. The present invention is considered to be particularly applicable to 14C analysis, and therefore the following disclosure relates to this. Preferably the particle beam is generated using the analyte sample inside an electron cyclotron resonance ion source operated to at least partially suppress the formation of molecules. Using such an ion source, the generated particle beam is preferably filtered to select the 14C2+ portion, and remaining interferences using a first mass spectrometer. The particle beam is then passed through a charge exchange cell. The charge exchange cell preferably contains sufficiently thick isobutane or similarly effective other gas to both convert positive incident 14C ions to negative ions and to suppress 13CH and 12CH2 interferences, thereby providing the treated particle beam. The treated particle beam is then preferably passed through a second mass spectrometer to select 14C−. The selected portion of the treated particle beam is received at the particle detector to detect 14C−. Further optional features of the invention are set out below. FIG. 1 shows a schematic of radiocarbon measurement according to an embodiment of the invention. Beginning in the electron cyclotron resonance (ECR) ion source, interferences to 14C detection are increasingly suppressed until reliable radiocarbon detection is possible. In FIG. 1, the two mass spectrometers each comprise an electrostatic spherical analyser (ESA) and dipole magnet. Component electrical-biasing is not shown but by manipulating the beam energy the carbon stable isotopes can be quantified with Faraday cup detectors. The mass spectrometer components shown in FIG. 1 are given by way of example only. They may be differently ordered, added to or subtracted from, and other components such as ion velocity Wien-filters may be substituted. As is the case of conventional AMS, the 14C is measured in ratio to stable 12C and/or 13C in the common beam from the ion source. The first spectrometer separates the radiocarbon from stable carbon ions which can then be measured as an electric current in a dedicated Faraday cup detector. The stable ions can be made to also pass through the charge-exchange cell and so also be measured free of hydrocarbon interference in dedicated Faraday cups after the second mass spectrometer by temporarily adjusting the ion energy of beam from the ion source so that the stable nuclides achieve the same rigidity as the radiocarbon ions and transmit the first mass spectrometer. The whole system is calibrated by separate measurements of the isotope ratios produced with standard sample materials of known carbon isotope ratios. Accordingly the production of ions in the ion source or in the charge-exchange cell need not be quantitative, but should preferably be consistent. Nevertheless high efficiency in these processes is desirable for expeditious sample measurement or low minimum sample size. FIG. 2 demonstrates ion source molecule suppression using stable isotopes. Positive carbon ion beams are extracted from a Pantechnik S. A. Nangon 10 GHz ECR plasma ion source newly mounted (at the time of writing) on an ion source deck of the Scottish Universities Environmental Research Centre (SUERC) bi-polar single-stage accelerator mass spectrometer (SSAMS) (Freeman et al (2008) and Freeman et al (2010)). The SUERC SSAMS is intended for routine conventional radiocarbon AMS but can also undertake positive-ion experimentation (Wilcken at al (2008)). This requires the reversal of some electrical and magnetic polarities but otherwise the spectrometer, including ion optical elements, ion detectors, data system and supporting vacuum and cooling systems, is operated similarly in either polarity. Existing sputter ion source control signals are co-opted to run the plasma ion source and the sample gas is delivered by an existing gas-handling system (Xu et al (2007)). The graph of FIG. 2 is of the 13C+/12C+ ratio obtained from the first mass spectrometer (see FIG. 1) where 12CH interferes with 13C. It is evident that the measured 13C/12C ratio can be reduced by increasing CO2 sample gas in the ion source or else by adding He carrier to increasingly remove 12CH from the ion beam until the expected 13C/12C ratio is reached. The same effect is employed for 14C measurement in the preferred embodiment of the present invention. The preferred embodiment of the invention for sample radiocarbon measurement suppresses interference to 14C detection in steps: Step 1: Partial hydrocarbon molecule suppression in an ECR ion source producing positive carbon ions in a variety of charge states from CO2 sample, optionally in the presence of He carrier gas. Step 2: Partial hydrocarbon molecule suppression by the selection of the 14C2+ with a first mass spectrometer. Step 3: Suitable additional hydrocarbon molecule suppression and 14N atomic isobar suppression with a thick non-metallic gas charge-exchange cell. Step 4: Resulting 14C− separation from molecular-fragments and remaining positive ions in the treated particle beam (exiting the charge-exchange cell) using a second mass spectrometer. Step 5: 14C− ion detection and counting with a final particle detector. The inventors observe that selecting the 2+ charge state partially suppresses molecular interference. It is considered that using this charge state for measuring natural-abundance 14C has not been disclosed previously. 1+ selection produces super-natural 14C measurement background at SUERC, whereas the selection of less-copious 3+ or even more highly charged positive ions is unnecessary. FIG. 3 shows why thick non-metal charge-exchange gas is employed to both remove remaining molecules and suppress 14N by ion charge inversion. FIG. 3 shows the ratio of C− to C+ ions exiting the SUERC SSAMS charge-exchange cell with various non-metallic gases measured with the instrument second mass spectrometer, using incident C2+ ions of the stable isotope noted. The SiN [7] data is from Wilcken et al. (2013) and the other dashed curves [1]-[6] from the references cited therein for comparison. Tenuous metal vapours are known as efficient means of charge-exchanging positive ions negative at low ion energy. However, molecule suppression requires sufficiently thick gas and therefore incident ion energies of 10 s keV or more to traverse the gas and be quantifiable with a mass spectrometer. At these energies non-metallic gases are considered to be similarly efficient. Also, such gases can be readily manipulated with conventional gas-handling equipment (mass-flow controllers, etc.), whereas metal-vapour control is more cumbersome and imprecise, and electrically-insulating gas cannot compromise the electric fields employed in mass spectrometry in a way that leaking metal vapour can. Moreover, a gas or gas blend can be chosen to provide the optimal combination of molecule suppression without excessive beam scattering and negative-ionisation. The gas requirements for good molecule suppression are the same as conventional AMS utilising thick stripper. Accordingly we can employ the same N2 gas metered into the same differentially-pumped open-ended tube between the mass spectrometers of the SSAMS as when the instrument is functioning conventionally. In that case this serves as the ‘stripper’-canal, whereas in the positive-ion method this serves as an electron-‘adder’. Gases other than pure N2 are conjectured to be the optimum, for example propane or isobutane. More electropositive gases such as isobutane are more efficient at donating electrons as shown in FIG. 3. The amount of gas employed is found empirically by adjusting gas flow whilst monitoring the measured 14C and stable carbon isotopes and their ratio. Gas thickness is an acceptable compromise of that best for molecule-removing and for charge-exchanging, and in a further improved embodiment can be adjusted automatically in feedback depending on the abundance of individual sample 14C and interferences. The beam energy is determined by the electrical biasing of the ion source and the charge-exchange cell deck. By the method of the present invention, and with radiocarbon-‘dead’ CO2 sample, radiocarbon measurement background of about 2% Modern (after correction for PIPS detector dark count) with 280 keV 14C ions has been achieved, chosen to match the ion energy employed when the SSAMS is operating conventionally, and good results also achieved at 140 keV, half this ion energy. This indicates that accelerator-free analysis is also possible in some embodiments in which ion source bias alone is sufficient. FIG. 4 shows the variation in C−/C+ ratio for multiple gas flow rates. It shows that negative ionisation efficiency is constant once there is gas flow sufficient for charge state equilibrium. The level of ionisation efficiency is dependent on the charge exchange gas used, as well as the ion energy. Radiocarbon background measurements with isobutane gas are also shown in FIG. 4. The background measurements were observed to be lowest where the gas flow was sufficient to destroy molecules without significantly scattering ions into the detector. Accordingly the described embodiment of the present invention is capable of reproducing the 14C abundance measurement range of the conventional AMS technique. This is done with an ion source superior to the sputter negative-ion sources normally used. By virtue of leveraged higher initial ion charge in the ion source biasing electric field, the new method is also a better route to accelerator-less 14C mass spectrometry than conventional AMS with potential considerable equipment cost savings. Additional details and explanations of the preferred embodiment and modifications of the preferred embodiment will now be set out. Particle Beam Source The positively charged particle beam is generated in an ion source such as electron cyclotron resonance (ECR), inductively couple plasma (ICP) or a capacitively coupled plasmas (CCP) ion source. An ECR ion source is the presently preferred ion source. It has the advantage over ICP and CCP in that it can readily make higher charge states than the 1+ and so is better at eliminating molecular interferences. Different charge states of the particle beam can be utilised from the ion source. Higher charge states, such as 3+ and above, have the advantage of being molecular free however they are more difficult to produce and therefore result in smaller beams (i.e. beams with fewer particles) and make less efficient use of the sample being measured. Going down in charge state to the 2+ and then 1+, the molecular interfering content increases but bigger and more efficiently produced beams are possible. In any charge state it is also possible to optimise the source conditions to reduce molecules, such as using an additional carrier gas such as He in the source (see FIG. 2). As explained above, the preferred embodiment uses the partial molecular suppression provided by the 2+ charge state which provides sufficient beam for accurate measurements. Sample Input Samples can be inputted into the ion source in solid, liquid or gas form. Sample loading can be automated. Samples can be pre-treated and prepared separately from the system or they can be taken directly from another system, such as in the example of carbon, CO2 can be combusted automatically from an organic source or generated in an elemental analyser and feed directly into the ion source. This has the advantage over conventional Cs sputter ion sources that typically only use samples prepared separately from the machine increasing labour and costs. In the case of carbon, the sample can comprise CO2 prepared separately. Ion Beam Analysis The system of the preferred embodiment is a high-resolution mass spectrometer. It utilises the different bending radius for charged particles with different momentum to identify the mass of the particles. An electrostatic analyser (ESA) and magnet work together to select mass, the magnet selects a momentum (i.e. species with the same mass*velocity combination) and the ESA selects the same energy regardless of mass. These steps are standard in mass spectroscopy. Interferences in this system are from particles with the same mass such as molecules or isobars. There is already at least partial molecular suppression in the ion source. The positive particle beam is then passed through the target gas in the charge exchange cell where the particles collide with the particles in the gas breaking apart the molecules. Ideally the target gas particles have a similar mass to the particle beam, i.e. heavy enough to create a strong collision and break the molecules apart without scattering the beam and destroying beam quality. The mass of the target gas is preferable to be similar to that of the ion beam for best performance, but it will work with other gases, but at potentially reduced performance. This removes the remaining molecular interferences. As the particle beam passes through and collides with the gas, it exchanges electrons with the gas, such that some of the particles in the beam will pick up additional electrons and become negatively charged. The charge exchange process works more efficiently when the target gas has low electronegativity. Metal vapours have low electronegativity, but are disadvantageous for the reasons already discussed. Of greater importance in the present invention is that the target gas is (or components of the target gas are) simple to flow in to the system. A metal vapour gas is difficult to maintain and it must be kept at a high temperature at all times to stop it condensing back into a liquid or solid. If metal gas vapour moves or migrates out of the charge exchange cell it can condense on insulators in the apparatus causing them to conduct and leading to potential electrical discharges. Using a gas which will not condense in use keeps the system cleaner and makes the system considerably simpler and cheaper to build. It is preferable that the gas has as low an electronegativity as possible but a high electronegativity may be acceptable provided that the loss in efficiency is acceptable. In some cases, the isobar of the particle of interest cannot create a negative beam. Some such cases are: 14N will not produce a negative beam to interfere with 14C, to measure its content in bulk carbon. Magnesium will not produce a negative beam to interfere with 26Al, to measure its content in bulk aluminium. Xenon will not produce a negative beam to interfere with 129I, to measure its content in bulk iodine. Manganese will not produce a negative beam to interfere with 55Fe, to measure its content in bulk iron. The target gas can be excited or pumped to improve performance. In the simplest case a DC bias can be applied longitudinally to the gas, this will act to accelerate electron which are liberated in a collision between the particle beam and the gas, the accelerated electrons will then interact further with the gas and, if the energy is sufficient, liberate more electrons and/or velocity match with particle beam and promote recombination and negative ion formation. Where the DC voltage and gas pressure is sufficiently high then a cascade effect of the secondary ions will produce a plasma DC discharge. Additional methods of creating a full plasma is to pump the gas with an alternating electro-magnetic field such as RF in a CCP or ICP or microwaves in other plasmas such as the ECR ion source. In this case the low mass electrons are accelerated quickly in the alternating field whereas the ion is too heavy to respond and will remain relatively stationary (this is the typical description of an AC plasma). As the particle beam passes through the plasma these fast moving oscillating electrons energetically collide multiple times with the particle beam causing improved ionisation and molecular dissociation and, in the case of plasma, donate electrons to the ion beam producing the negative ions where the plasma cools or de-excites again. System Description FIG. 1 is now described in more detail. This refers to carbon measurement, but the system can be adapted to apply to the other isotopes discussed above. CO2 gas 1 is added to the ECR ion source 3 where it is ionised, molecules are at least in part broken up and a particle beam 5 is accelerated out of the ion source. A dipole magnet 7 is used to select, for example, the 2+ carbon atoms for further analysis. The abundant isotopes, 12C and 13C, are measured in off-axis Faraday cups 10 (the axis of the rare isotope being on-axis), whereas the rare isotope, 14C, is selected for further processing to remove the interferences of molecules such as 13CH2+, and its isobar 14N2+. A fast switching DC bias can be applied to the first magnet vacuum manifold to alter the energy and therefore momentum of the abundant isotope to allow it to be switched on-axis, in this instance the off-axis cups to measure the abundant isotope is situated after the second magnet. A gas cell 12, consisting of a tube 14 where a small amount of gas is flowed in through a mass flow controller 16 or other needle valve, flows down the tube and removed by differential pumping at either end. The on-axis isotope beam 18 passes through the tube where it interacts with the gas, significantly destroying the remaining molecules and charge exchanging so that the beam exiting the gas cell 20 has negligible molecules and a range of charge states for example, 20% in 1−, 50% neutral and 30% in 1+. All nitrogen is neutral or positively charged. An ESA and dipole magnet 22 (in any order) are then used to select the 14C1− particles, which are now free from any molecules or isobars, and send them to a single particle detector 24. Another variation on the system is to remove the first selection magnet and pass everything through the clean-up stage in the gas cell, in which case the 12C, 13C and 14C are all measured in the 1− charge state after the magnet. While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the invention. All references referred to above and in the lists below are hereby incorporated by reference. The reference numbers in square brackets below are references for the data points used in FIG. 3 and are distinct from other reference numbers not in square brackets used elsewhere in the application. [1] J. H. Ormrod, W. L. Michel, Can. J. Phys. 49 (1971) 606-620 [2] J. Heinemeier, P. Hvelplund, Nucl. Instr. Meth. 148 (1978) 425-429 [3] J. Heinemeier, P. Hvelplund, Nucl. Instr. Meth. 148 (1978) 65-75 [4] B. Christensen et al, Phys. Rev. A 18 (1978) 2042-2046 [5] W. N. Lennard et al, Nucl. Instr. Meth. 179 (1981) 413-419 [6] W. N. Lennard et al, Rhys. Rev. A 24 (1981) 2809-2813 [7] K. M. Wilcken et al, Nucl. Instr. Meth. B 294 (2013) 353-355 [8] S. P. H. T. Freeman et al, Nucl. Instr. Meth. B (2015) http://dx.doi.org/10.1016/j.nimb.2015.04.034 Hans-Arno Synal, Developments in accelerator mass spectrometry, International Journal of Mass Spectrometry 349-350 (2013) 192-202 Walter Kutschera, Applications of accelerator mass spectrometry, International Journal of Mass Spectrometry 349-350 (2013) 203-218 Stewart P. H. T. Freeman, Andrew Dougans, Lanny McHargue, Klaus M. Wilcken, Sheng Xu, Performance of the new single stage accelerator mass spectrometer at the SUERC, Nuclear Instruments and Methods in Physics Research B 266 (2008) 2225-2228 Stewart P. H. T. Freeman, Gordon T. Cook, Andrew B. Dougans, Philip Naysmith, Klaus M. Wilcken, Sheng Xu, Improved SSAMS performance, Nuclear Instruments and Methods in Physics Research B 268 (2010) 715-717 K. M. Wilcken, S. P. H. T. Freeman, S. Xu, A. Dougans, Positive ion AMS with a single-stage accelerator and an RF-plasma ion source at SUERC, Nuclear Instruments and Methods in Physics Research B 266 (2008) 2229-2232 Sheng Xu, Andrew Dougan, Stewart P. H. T. Freeman, Colin Maden, Roger Loger, A gas ion source for radiocarbon measurement at SUERC, Nuclear Instruments and Methods in Physics Research B 259 (2007) 76-82 Roy Middleton, On the possibility of counting 14C− ions without an accelerator, Proceedings of the First Conference on Radiocarbon Dating with Accelerators held at The University of Rochester Apr. 20 and 21, 1978 Edited by H. E. Gove, 157-164 Ronald Schubank, A low-energy table-top approach to AMS, Nuclear Instruments and Methods in Physics Research B 172 (2000) 288-292 Michael Hotchkis, Tao Wei, Radiocarbon detection by ion charge exchange mass spectrometry, Nuclear Instruments and Methods in Physics Research B 259 (2007) 158-164 F. W. Meyer, E. Galutschek, M. Hotchkis, Low-energy grazing ion-scattering from Alkali-Halide surfaces: a novel approach to C-14 detection, AIP Conf. Proc. 1099 (2009) 308-313 M. L. Robert, R. J. Schneider, K. F. von Reden, J. S. C. Wills, B. X. Han, J. M. Hayes, B. E. Rosenheim, W. J. Jenkins, Progress on a gas-accepting ion source for continuous-flow accelerator mass spectrometry, Nuclear Instruments and Methods in Physics Research B 259 (2007) 83-87 K. M. Wilcken, S. P. H. T. Freeman, S. Xu, A. Dougans, Attempted positive ion radiocarbon AMS, Nuclear Instruments and Methods in Physics Research B 268 (2010) 712-714 K. M. Wilcken, S. P. H. T. Freeman, S. Xu, A. Dougans, Single-stage accelerator mass spectrometer radiocarbon-interference identification and positive-ionisation characterisation, Nuclear Instruments and Methods in Physics Research B 294 (2013) 353-355
	summary
053902203	summary	In a boiling water nuclear reactor fuel bundle, a debris catching arrangement is disclosed for incorporation within the flow volume between the inlet nozzle and the rod supporting grid of the lower tie plate assembly. The particular debris catcher arrangement includes a matrix of coil springs loaded preferably within the lower tie plate flow plenum of the lower tie plate between the inlet nozzle and the bottom of the rod supporting grid. BACKGROUND OF THE INVENTION Boiling water nuclear reactors operate for many years. Commencing with their initial construction and through their service lives, these reactors may accumulate debris in their closed circulation moderator systems. This debris can become an operating hazard if the debris is allowed to enter into the fuel bundle containing core region having the heat generating fuel rods. In order to understand this problem, a summary of reactor construction as it relates to the accumulation of debris in the core needs first to be given. Thereafter, fuel bundle construction will be set forth. Emphasis will be given to the need to preserve substantially unchanged the regions of pressure drop within the fuel bundles. Thereafter, the effects caused by debris entering into the fuel rod region of the fuel bundles will be summarized. Boiling water nuclear reactor construction can be simply summarized for purposes of understanding the debris entrainment problem. Such nuclear reactors are provided with a large, central core. Liquid water coolant/moderator flow enters the core from the bottom and exits the core as a water steam mixture from the top. The core includes many side-by-side fuel bundles. Water is introduced into each fuel bundle through a fuel bundle support casting from a high pressure plenum which is situated below the core. Water passes in a distributed flow through the individual fuel bundles, is heated to generate steam, and exits the upper portion of the core as a two phase water steam mixture from which the steam is extracted for the generation of energy. The core support castings and fuel bundles are a source of pressure loss in the circulation of water through the core. This pressure loss assures the substantially even distribution of flow across the individual fuel bundles of the reactor core. When it is remembered that there are as many as 750 individual fuel bundles in a reactor core, it can be appreciated that assurance of the uniformity of flow distribution is important. To interfere with the pressure drop within the fuel bundles could affect the overall distribution of coolant/moderator within the fuel bundles of the reactor core. Having set forth the construction of the boiling water nuclear reactor in so far as is appropriate, attention can now be directed to the construction of the fuel bundles themselves. The fuel bundles for a boiling water nuclear reactor include a fuel rod supporting lower tie plate assembly, which lower tie plate assembly is a cast structure. The lower tie plate assembly includes at its lowest point a downward protruding bail covering an inlet nozzle. This inlet nozzle includes entry to an enlarged flow volume within the lower tie plate. At the upper end of the flow volume, there is located a rod supporting grid. Between the supporting grid and the nozzle there is defined a flow volume. The rod supporting grid has two purposes. First, the rod supporting grid provides the mechanical support connection for the weight of the individual fuel rods to be transmitted through the entire lower tie plate to the fuel support casting. Secondly, the rod supporting grid provides a flow path for liquid water moderator into the fuel bundle for passage between the side-by-side supported fuel rods. Above the lower tie plate, each fuel bundle includes a matrix of upstanding fuel rods--sealed tubes each containing fissionable material which when undergoing nuclear reaction produce the power generating steam. The matrix of upstanding fuel rods includes at the upper end a so-called upper tie plate. This upper tie plate holds at least some of the fuel rods in vertical side-by-side alignment. Some of the fuel rods are attached to both the upper and lower tie plates. Usually, there are included between the upper and lower tie plates water rods for improvement of the water moderator to fuel ratio, particularly in the upper, highest void fraction region of the fuel bundle. Fuel bundles also include about seven fuel rod spacers at varying elevations along the length of the fuel bundle. These spacers are required because the fuel rods are long (about 160 inches) and slender (about 0.4 to 0.5 inches in diameter), and would come into abrading contact under the dynamics of fluid flow and nuclear power generation within the fuel bundles. The spacers provide appropriate restraints for each fuel rod at their respective elevations and thus prevent abrading contact between the fuel rods and maintain the fuel rods at uniform spacing relative to one another along the length of the fuel bundle for optimum performance. As will hereafter be developed, these spacers are sites where debris can be trapped and damage the fuel rods. Each fuel bundle is surrounded by a channel. This channel causes water flowing between the tie plates to be restricted to only one bundle in an isolated flow path between the tie plates. The channel also serves to separate the steam generating flow path through the fuel bundles from the surrounding core bypass region, this region being utilized for the penetration of the control rods. The water in the bypass region also provides neutron moderation. In the operation of a boiling water nuclear reactor, it is important to understand that the maintenance of the originally designed flow distribution is important. Specifically, from the lower (high pressure) plenum inlet to the core to the outlet from the core of the steam and water mixture through the upper tie plates of the fuel bundles, about 20 pounds per square inch (psi) of pressure drop is encountered at typical 100% power/100% flow operating conditions. About 7 to 8 psi of this pressure drop occurs through the fuel support casting. This pressure drop is mainly to assure the uniform distribution of coolant/moderator flow through the many fuel bundles making up the core of the reactor and is related to the prevention of operating instabilities within the reactor at certain power rates of the reactor. At the lower tie plate of each fuel bundle, from the inlet nozzle into the flow volume and through the fuel rod supporting grid, about 1 to 11/2 psi pressure drop occurs which contributes to establishing flow distribution between the individual fuel rods of each fuel bundle. Finally, through the fuel bundle itself--from the lower supporting grid to the exit at the upper tie plate--about 11 psi of pressure drop usually occurs. When new fuel bundles are introduced into a reactor core, these pressure drops must be preserved. Otherwise, the coolant/moderator flow distribution could be compromised. Having summarized the construction and operation of a boiling water nuclear reactor, the problem of debris resident within the closed circulation moderator system of the reactor can now be understood. Typically debris within boiling water nuclear reactors can include extraneous materials left over from reactor construction. Further, corrosion during the reactor lifetime also liberates debris. Finally, and during the numerous outages and repairs, further debris accumulates. It will therefore be understood that nuclear reactors constitute closed circulation systems that essentially accumulate debris with increasing age. It has been discovered that a particularly vexing and usual place for the accumulation of debris is in the fuel bundles between the fuel rods particularly in the vicinity of the fuel rod spacers. It will be remembered that each fuel rod is surrounded by the spacer at the particular elevation of the spacer. Debris particles tend to lodge between the spacer structure and the fuel rods and often dynamically vibrate with the coolant/moderator flow in abrading contact to the sealed cladding of the fuel rods. Such flow induced vibration within the reactor, can and has both damaged--as by fretting--as well as ruptured the cladding of the fuel rods. If a sufficient number of cladding ruptures occurs, plant shutdown could be necessary. It is to be understood that modern nuclear plants have both redundancy and many safety systems designed to counter act anticipated operating casualties, such as fuel rods becoming punctured by debris. Such failures are not catastrophic. However, in almost all cases they result in the plant operating at less than optimum efficiency. Thus, it is highly desirable to reduce the incidence of debris damage to fuel rods. It will be further understood that to a certain extent the rod supporting grid of the fuel bundle acts as a strainer. Debris exceeding the dimension of the grid cannot pass to the fuel bundles. However, it has been found that debris--especially debris with "sail areas"--such as metal shavings, wire and the like--work past the rod supporting grid and can become lodged between the fuel rods and spacers. SUMMARY OF THE PRIOR ART Prior art attempts at the placement of devices for preventing debris from entering into the regions of the fuel rods have included alteration of the grid support structure of the lower tie plate assembly. In Nylund U.S. Pat. No. 5,100,611 issued Mar. 31, 1992, an alteration to the grid structure is disclosed. This alteration includes replacing the required through holes of the grid structure with flow channel parts that have center lines that are non-collinear. Because these flow channels are part of the fuel rod supporting grid, the size of the through holes is necessarily large to preserve the rod supporting grid strength and the area over which the holes are distributed is only co-extensive to the lower tie plate assembly at the supporting grid. Attempts to screen debris have been made in pressurized water reactors. In Bryan U.S. Pat. No. 4,664,880 issued May 12, 1987 a wire mesh debris trap is utilized at the bottom of a pressurized water reactor fuel bundle. In Rylatt U.S. Pat. No. 4,678,627 issued Jul. 7, 1987, this structure is modified to include a debris retaining trap. These pressurized water reactor fuel bundles constitute open structures and lack the channel confined flow path between the upper and lower tie plates common to boiling water nuclear reactors. The channel structure, required in boiling water nuclear reactor construction, is wholly absent in pressurized water reactor construction. Since flow can occur between adjacent fuel bundles in a pressurized water reactor along the entire length of the fuel bundles, the placement of the disclosed screens and traps does not occur within a confined flow path. Further, such fuel bundles lack the disclosed lower tie plate assembly utilized with boiling water reactors including the inlet nozzle, and the defined flow volume to rod supporting grid at the bottom of the fuel bundles. In one prior art debris catching device, the lower tie plate is modified with serpentine path--almost in the form of a chevron. Overlying this construction there are placed rod supporting bars so that the weight of the rods does not crush the underlying serpentine path. SUMMARY OF THE INVENTION In a boiling water nuclear reactor fuel bundle, a debris catching arrangement is disclosed for incorporation within the flow plenum upstream or below the rod supporting grid of the lower tie plate assembly. The device is preferably placed within the lower tie plate flow plenum between the fuel bundle inlet orifice and the rod supporting grid structure supporting the fuel rods; alternate placement can include any inlet channel upstream of the fuel rods including the fuel support casting. The disclosed debris catching designs include successive side-by-side coil springs placed in layers across the tie plate plenum. Preferably, the respective layers are placed in alternating directions with a first layer of springs oriented at 90.degree. to an alternate and underlying layer of springs. Multiple layers of such springs are used with four layers being preferred. At their respective crossing points, the springs of adjacent layers are joined--as by welding--with the result that the filter is a solid unitary mass.
048658022	claims	1. An accumulator whose principal purpose is to allow for thermal expansion of a liquid where said accumulator is adapted to operate in a zero gravity environment comprising: a single closed vessel containing a plurality of elongated tubes, each tube having a fluid passageway therethrough for capillary containment of said liquid; a grid member having openings therein for receiving one end of each of said tubes in sealing engagement such that the passageways in said tubes provide the sole means for fluid communication through said grid plate; a housing having wall members surrounding the periphery of and in sealing engagement with said grid plate and a base member, said wall member, base member and grid member forming a liquid zone; a body of said liquid in said liquid zone and extending partially into each of said tubes; a body of gas contained in an opposite end of said tubes; and a conduit means located adjacent said base member of said vessel for the introduction of said liquid into and withdrawal of said liquid from said liquid zone to accommodate thermal expansion and contraction respectively of said liquid. 2. The accumulator of claim 1 wherein said liquid is a liquid metal and said gas is an inert gas. 3. The accumulator of claim 1 wherein each of said tubes has an internal diameter within the range of from about 0.5 to 10 millimeters. 4. The accumulator of claim 1 wherein said tubes and grid member are totally enclosed within said housing. 5. The accumulator of claim 1 wherein each of said tubes are closed at an end opposite said grid member for containing said body of gas. 6. The accumulator of claim 1 wherein said conduit means is in fluid communication with the primary coolant of a liquid metal-cooled nuclear reactor required to operate in a space environment. 7. The accumulator of claim 2 wherein each of said tubes has an internal diameter within the range of from about 0.5 to 100 millimeters. 8. The accumulator of claim 7 wherein said tubes and grid member are totally enclosed within said housing. 9. The accumulator of claim 7 wherein each of said tubes are closed at an end opposite said grid member for containing said body of gas. 10. The accumulator of claim 8 or 9 wherein said conduit means is in fluid communication with the primary coolant of a liquid metal-cooled nuclear reactor required to operate in a space environment.
	description	This application claims the benefit of Chinese Patent Application No. 201811384620.4, entitled “Flat panel detector and method of manufacturing the same,” filed with the State Intellectual Property Office of China on Nov. 20, 2018, the whole disclosure of which is incorporated herein by reference. Embodiments of the present disclosure relate to the field of flat panel detectors, and particularly to a flat panel detector and a method of manufacturing the same. Flat-panel detectors have a wide range of applications in medical imaging and industrial inspection. Since functions of light absorption, conversion and signal reading are necessarily achieved by means of thin film transistors and PIN photodiodes, while these types of detectors have a disadvantage of a low filling rate due to an inherent size of thin film transistors, a PIN photo sensor has a reduced light absorption area and thus a reduced detection sensitivity. Embodiments of the present disclosure provide a flat-panel detector and a method of manufacturing the same, which at least increase a filling rate, a light absorbing area and a detecting sensitivity of an amorphous silicon flat-panel detector. Embodiments of the present disclosure provide a flat-panel detector, including: a-ray conversion layer configured to convert a ray into a light having a first wavelength; and a plurality of imaging units, at least one of the imaging units comprising: a photo sensor configured for receiving the light and converting the light to an electrical signal; and a light guider located a side of the photo sensor adjacent to the ray-conversion layer, the light guider having a light entry surface adjacent to the ray-conversion layer and a light exit surface adjacent to the photo sensor, the light entry surface being configured to receive the light from the ray-conversion layer and having an area greater than an area of the light exit surface, and an orthogonal projection of the light exit surface in a direction perpendicular to the ray-conversion layer at least partially overlapping that of the photo sensor. In an embodiment, at least one of the imaging units further comprises: a read circuit electrically connected to the photo sensor and configured to read a signal provided by the photo sensor. In an embodiment, the light guider comprises a fiber optic taper comprising a first end and a second end that are opposite to each other, the first end is the light entry portion, the second end is the light exit portion, and the fiber optic taper is disposed in one-to-one correspondence with the photo sensor so that the light having the first wavelength is transmitted, via the light exit surface of the second end of the fiber optic taper, to the photo sensor. In an embodiment, a reflective layer is disposed on a tapered wall of the fiber optic taper. In an embodiment, the photo sensor comprises a photodiode, and an orthogonal projection of the second end of the fiber optic taper in a direction perpendicular to the ray-conversion layer coincides with that of the photodiode. In an embodiment, the read circuit comprises at least one of the group of an amorphous silicon thin film transistor, an oxide thin film transistor and an polysilicon thin film transistor. In an embodiment, the flat-panel detector further includes a light-shielding layer disposed between the read circuit and the ray-conversion layer. In an embodiment, the flat-panel detector further includes a passivation layer disposed on a side of the light-shielding layer facing away from the read circuit. In an embodiment, the photodiode is connected to a drain electrode of the read circuit through a conductive element formed from a metal layer. In an embodiment, the ray-conversion layer comprises an array of cesium iodide scintillation crystals or Gd2O2S:Tb particles. In an embodiment, the light having the first wavelength ranged from 400 nm to 800 nm. Embodiments of the present disclosure further provide a method of manufacturing the above mentioned flat-panel detector, the method including steps of: forming sequentially a photoelectric conversion layer comprising the photo sensor, a light transmission layer comprising the light guider, and the ray-conversion layer. In an embodiment, the fiber optic taper is provided with a reflective layer that is made of metal on a tapered wall thereof, and the reflective layer is formed by depositing a metal material on the tapered wall of each of the fiber optic tapers by a magnetron sputtering method or a electroplating method. In an embodiment, the forming sequentially the photoelectric conversion layer, the light transmission layer, and the ray-conversion layer comprises: forming an amorphous silicon thin film transistor on the substrate; forming a first metal layer on the substrate on which the previous step is performed and bridging the first metal layer with a drain electrode of the amorphous silicon thin film transistor via a through hole as an extension of the drain electrode; forming a photodiode as a photo sensor on the substrate on which the previous steps are completed; coupling a light exit surface of the fiber optic taper right above the photodiode; and vapor depositing or bonding scintillators of a material onto the light entry surfaces of the fiber optic taper, and arranging them in array as the ray-conversion layer. In an embodiment, the method further includes: after forming the photodiode, forming a second metal layer over the photodiode, and then, simultaneously forming a signal line and a light-shield layer covering the amorphous silicon thin film transistor by a single patterning process. In an embodiment, the method further includes: after forming the light-shielding layer, coating a resin material or depositing a transparent passivation film layer to form a passivation layer. The present disclosure will be further described in detail below in conjunction with the drawings and specific embodiments. Embodiments of the present disclosure provide a flat-panel detector, as shown in FIG. 1, including a ray-conversion layer 1, a photoelectric conversion layer 2, and a light transmission layer 3. In the embodiment, the light transmission layer 3 is provided between the ray-conversion layer 1 and the photoelectric conversion layer 2. The ray-conversion layer 1 is provided to convert a ray into a light having a first wavelength. The first wavelength is greater than a wavelength of the ray. In the embodiment, the first wavelength may be in a range from 800 nm to 100000 nm (i.e., the light is an infrared wave light), or in a range from 400 nm to 800 nm (i.e., the light is visible light), or in a range from 100 nm to 400 nm (i.e., the light is ultraviolet light). In an embodiment, the first wavelength is ranged from 400 nm to 800 nm. The light transmission layer 3 is capable of transmitting the light having the first wavelength converted by the ray-conversion layer 1 to the photoelectric conversion layer 2. In an embodiment, the light transmission layer 3 includes a light entry portion and a light exit portion, and the light transmission layer 3 is disposed such that an area of a light entry surface of the light entry portion is greater than an area of a light exit surface of the light exit portion, and the light entry portion is adjacent to the ray-conversion layer 1 such that the light having the first wavelength converted by the ray-conversion layer 1 enters the light transmission layer 3 through the light entry portion and is converged in the light transmission layer 3 and then is passed through the light exit portion to the photoelectric conversion layer 2. The photoelectric conversion layer 2 is configured to convert the light having the first wavelength received into an electrical signal for being read. In an embodiment, the ray-conversion layer 1 may be an X-rays conversion layer; in an embodiment, the ray-conversion layer 1 may be a Gamma ray-conversion layer; in another embodiment, the ray-conversion layer 1 may be a conversion layer for converting another type of ray. In an embodiment, the photoelectric conversion layer 2 may include a plurality of conversion units 20, each including a photo sensor 21 and a read circuit 22 connected to the photo sensor 21. The photo sensor 21 is provided for receiving the light having the first wavelength from the light exit portion of the light transmission layer 3 and converting the light having the first wavelength into the electrical signal. The read circuit 22 is provided for reading the electrical signal of the photo sensor 21. The flat-panel detector according to the embodiment collects the light having the first wavelength converted by the ray-conversion layer 1 by using the light entry surface of the light transmission layer 3 having a greater area and after convergence, transmits it, by the light exit surface having a smaller area, to the photo sensor 21, which is equivalent to an improvement of a rate of absorption of the light having the first wavelength of the ray-conversion layer 1 by the photo sensor 21 and an improvement of a detection sensitivity. The flat-panel detector may be used in medical applications to reduce a ray radiation dose absorbed by a patient while protecting medical personnel. In an embodiment, there is provided a flat-panel detector including: a ray-conversion layer 1 configured to convert a ray into a light having a first wavelength, the first wavelength being greater than a wavelength of the ray; and a plurality of imaging units 20. In the embodiment, each of the plurality of imaging units 20 includes: a photo sensor 21 configured for receiving the light and converting the light to an electrical signal; and a light guider 3 located a side of the photo sensor 21 adjacent to the ray-conversion layer 1, the light guider 3 having a light entry surface adjacent to the ray-conversion layer 1 and a light exit surface adjacent to the photo sensor 21. The light entry surface is configured to receive the light from the ray-conversion layer 1 and has an area greater than an area of the light exit surface, and an orthogonal projection of the light exit surface in a direction perpendicular to the ray-conversion layer 1 at least partially overlaps that of the photo sensor 21. In an embodiment, the flat-panel detector may include a base substrate and the ray-conversion layer 1 is located on the based substrate and the plurality of imaging units 20 are located between the base substrate and the ray-conversion layer 1. However, it is noted that a base substrate is not necessary for the present disclosure. In an embodiment, each of the plurality of imaging units 20 further includes a read circuit 22 electrically connected to the photo sensor 21 and configured to read a signal provided by the photo sensor 21. The read circuit 22 comprises at least one of the group of an amorphous silicon thin film transistor, an oxide thin film transistor and an polysilicon thin film transistor. In an embodiment, the first wavelength may be ranged from 400 nm to 800 nm. It is noted that in the above embodiments a term of imaging unit 20 is used and it in fact is a name of a combination of the photo sensor 21 and the light guider 3 or a combination of the photo sensor 21, the light guider 3 and the read circuit 22. Another different name may be used by those skilled in the art for the above combination and the different used name does not mean a new component being added. In another embodiment, components of the flat-panel detector according to the present disclosure are described by reference to layer(s). Embodiments of the present disclosure provide a flat-panel detector, as shown in FIGS. 2-8, including a ray-conversion layer 1, a photoelectric conversion layer 2, and a light transmission layer 3, wherein the light transmission layer 3 is disposed between the ray-conversion layer 1 and the photoelectric conversion layer 2. The photoelectric conversion layer 2 may include a plurality of conversion units 20, each including a photo sensor 21 and a read circuit 22 connected to the photo sensor 21. The light transmission layer 3 includes a plurality of fiber optic tapers 30 arranged in one-to-one correspondence with the photo sensor 21 of the plurality of conversion units 20. In an embodiment, as shown in FIG. 4, the fiber optic taper 30 has a first end 31 and a second end 32 opposite to each other. The first end 31 is the light entry portion, and the second end 32 is the light exit portion. The area of the light entry surface of the first end 31 is greater than the area of the light exit surface of the second end 32. The fiber optic tapers 30 are arranged in one-to-one correspondence with the photo sensor 21 of the plurality of conversion units 20 so that the light having the first wavelength is transmitted from the light exit surfaces of the second end 32 of each of the fiber optic tapers 30 to one of the photo sensors 21. The light having the first wavelength entering the fiber optic taper 30 from the ray-conversion layer 1 can be converged and then transmitted by the fiber optic taper 30 to the photo sensor 21. In an embodiment, the ray-conversion layer 1 converts entered rays into a light having the first wavelength, which is of about 550 nm, then the fiber optic tapers 30 converge the light having the first wavelength and transmits it, via the second end 32, to the photo sensor 21, and the photo sensor 21 receives the light having the first wavelength from the light exit portion of the light transmission layer 3 and converts it into an electrical signal. The read circuit 22 is used to read the electrical signal of the photo sensor 21. It should be understood that in another embodiment, the ray-conversion layer 1 can convert the entered rays into a light having other wavelengths, such as in a range from 400 nm to 800 nm, i.e., visible light. In the embodiment, the fiber optic tapers 30 may be an image transmission device including a plurality of optical fibers with a diameter in a range from 5 μm to 6 μm. The optical fibers are regularly arranged in a certain shape, such as a circular shape, an elliptic shape, a rectangular shape, etc., which may be designed depending on actual conditions. Further, each fiber is formed in a tapered shape by uniformly stretching at one end. It should be understood that the fiber optic taper 30 may be in a regular pyramidal or conical shape as a whole, however, the fiber optic taper 30 may be partially in a pyramidal or conical shape, but as a whole is not in a strictly pyramidal or conical shape, provided it could converge light. In a general ray detection, the presence of the light having the first wavelength in the detector indicates that a ray is detected, achieving a simple ray detection function. In an embodiment, the fiber optic taper 30 has a function of enlarging or reducing an image, which requires that the fiber optic taper 30 should have not only a function of converging light, but also a regular shape so that the convergence of light is uniform. Specifically, the fiber optic taper 30 may be an image transmission device that can provide a distortion-free image transmission with an image enlarged or reduced, and a magnification or a reduction ratio is equal to a ratio between diameters of two end faces of the fiber optic taper. The fiber optic taper 30 used herein may be an image transmission device that transmits an image with reducing the image without distortion. Similar to other fiber optic components, each of the fiber optic tapers 30 has optical insulation property and can independently transmit light without being affected by adjacent optical fibers. When an image is inputted to ends of the fiber optic tapers 30, the image is decomposed by tens of millions of fibers included by the fiber optic tapers 30 into image elements each corresponding to one fiber. The fibers that are regularly arranged will transmit the image element information carried by them to the other ends of the fiber optic tapers. The image elements are enlarged or reduced with changing of the diameter of each of the optical fibers (each having a circular light entry surface and a circular light exit surface) or a side length of each of the optical fibers (each having a rectangular light entry surface and a rectangular light exit surface) during transmission of the image, and are combined into an image on the light exit surfaces in their original arrangement. The specific shape of the fiber optic taper 30 is not limited herein. For example, the fiber optic taper 30 may have a circular or a rectangular shape. In an embodiment, as shown in FIGS. 3 and 4, a reflective layer 33 may be disposed on a tapered wall of each of the fiber optic tapers 30. In the embodiment, the reflective layer 33 is configured to prevent lateral diffusion of a light having the first wavelength between adjacent ones of the fiber optic tapers 30, and thus to prevent light crosstalk between adjacent ones of the fiber optic tapers 30. In an embodiment, the reflective layer 33 is made of a metallic material. For example, the reflective layer 33 may be made of an aluminum (Al) material, as Al has a high reflectance and is easy to be coated. In an embodiment, as shown in FIGS. 5 and 6, the ray-conversion layer 1 is composed of an array of cesium iodide scintillation crystals 10 or GOS (Gd2O2S:Tb) particles. Specifically, the array of cesium iodide scintillation crystals 10 include a plurality of cesium iodide scintillation crystals that are in an acicular shape and independent of each other. Herein, an acicular shape may be specifically a cylindrical shape or a shape close to a cylinder. Generally, a thickness of the ray-conversion layer 1 formed by the array of cesium iodide scintillation crystals 10 may be in a range from 100 μm to 1000 μm, however, the specific thickness of the ray-conversion layer 1 is not limited thereto. In an embodiment, the photo sensor 21 includes a photodiode. As shown in FIGS. 7 and 8, an orthogonal projection of the second end 32 of the fiber optic taper 30 in a direction perpendicular to the ray-conversion layer 1 is coincident with that of the photodiode in the direction perpendicular to the ray-conversion layer 1. In the embodiment, the photodiode converts the light having the first wavelength into a positive electric charge signal and a negative electric charge signal under the action of the light having the first wavelength irradiation. In an embodiment, the read circuit 22 includes an amorphous silicon thin film transistor. In an embodiment, the read circuit 22 performs control by the amorphous silicon thin film transistor, and reads the electrical signal converted by the photodiode and sends it to a signal storage unit (not shown), so as to obtain an image information upon a further amplification and A/D conversion. In an embodiment, the orthogonal projection of the amorphous silicon thin film transistor in the direction perpendicular to the ray-conversion layer 1 does not overlap that of the photodiode. In an embodiment, during manufacturing the flat-panel detector, the amorphous silicon thin film transistor is formed firstly, and then the photodiode is formed. If the orthogonal projection of the crystalline silicon thin film transistor in the direction perpendicular to the ray-conversion layer 1 overlaps with that of the photodiode, that is, the photodiode is formed on the amorphous silicon thin film transistor, the subsequent formation of the photodiode may adversely affect the amorphous silicon thin film transistor. According to an embodiment of the present disclosure, the amorphous silicon thin film transistor and the photodiode are configured such that their orthogonal projections in the direction perpendicular to the ray-conversion layer 1 do not overlap and damage to the amorphous silicon thin film transistor can be avoided. In an embodiment, the photodiode is connected to a drain electrode of the amorphous silicon thin film transistor by a wire formed by a metal layer. In this configuration, it is equivalent to extend the drain electrode of the amorphous silicon thin film transistor, thereby facilitating connection with the photodiode, and a surface of the extending metal layer is smooth with less etching damage, which is favorable to obtaining photodiode with a high quality and further avoiding peel-off phenomenon of the photodiode. In an embodiment, a light-shielding layer 23 is disposed between the amorphous silicon thin film transistor and the ray-conversion layer 1. As shown in FIG. 3, a light-shielding layer 23 is disposed over and covers the amorphous silicon thin film transistor to obtain a further protection of the amorphous silicon thin film transistor from light radiation. In an embodiment, the photoelectric conversion layer 2 may further include a signal line connected to the photodiode, the signal line being disposed between the photodiode and the light transmission layer 3, and being usually made of metal. In the embodiment, the light-shielding layer 23 is also made of metal, and the light-shielding layer 23 may be in the same layer as the signal line, that is, the signal line may be formed with the light-shielding layer 23 by a single patterning process. In an embodiment, a passivation layer 24 is provided on a side of the light-shielding layer 23 that faces away from the amorphous silicon thin film transistor. According to the present embodiment, the passivation layer 24 is provided between the light transmission layer 3 and the photoelectric conversion layer 2 including the amorphous silicon thin film transistor and the photodiode to obtain a planarization and a protection of the photoelectric conversion layer 2. In the drawings corresponding to the present embodiments, sizes, thicknesses, and the like of the structural layers shown in the drawings are shown for illustration. In the process implementation, projected areas of the structural layers on the substrate may be the same or different. Embodiments of the present disclosure provide a method for manufacturing the above flat-panel detector, as shown in FIG. 3, including the following steps. In step S01, an amorphous silicon thin film transistor is formed on a substrate. Specifically, a top gate type or a bottom gate type amorphous silicon thin film transistor can be formed on the substrate to fabricate a read circuit 22. In step S02, a first metal layer is deposited on the substrate on which the above step is completed, and the first metal layer is bridged with a drain electrode of the above thin film transistor via a through hole as an extension of the drain electrode. This configuration may ensure a film layer above it to have a good deposition quality and prevent the film layer from peeling off. In step S03, a photodiode is formed as a photo sensor 21 on the substrate on which the above steps are completed, a passivation layer is deposited by a single process or a resin is coated, and a signal line which is connected to the photodiode via a through hole is prepared. In an embodiment, the amorphous silicon thin film transistor and the photodiode may be arranged such that their orthogonal projections in a direction perpendicular to the ray-conversion layer 1 have no overlapping. It should be noted that, in the embodiment, a second metal layer may be formed over the photodiode, and may be formed simultaneously by a single patterning process into the signal line and the light-shielding layer 23 of the amorphous silicon thin film transistor. In step S04, a passivation layer 24 is formed by coating a layer of resin material or depositing another transparent passivation film layer. In step S05, a second end 32 of each of the fiber optic tapers 30 is coupled to right above the photodiode, wherein the second end 32 of each of the fiber optic tapers matches a size of the photodiode, i.e., the faces of them opposing to each other have the same area. As an example of the embodiment, the step further includes a step of forming a reflective layer 33 that is made of metal on the tapered wall of each of the fiber optic tapers 30. Specifically, the reflective layer 33 that is made of metal may be formed by depositing a metal material on the tapered wall of each of the fiber optic tapers 30 by a magnetron sputtering method or an electroplating method. In step S06, scintillators of a material such as CsI or GOS are vapor-deposited or bonded on the first ends 31 of the fiber optic tapers 30, respectively, and arrayed in order to form an array as the ray-conversion layer 1. It is understood that the above embodiments are merely exemplary embodiments employed to explain the principles of the present disclosure, but the present disclosure is not limited thereto. Various modifications and improvements can be made by those skilled in the art without departing from the spirit and scope of the disclosure, and such modifications and improvements are also considered as falling within the scope of the present disclosure.
043550010	abstract	A reactor unit and a nuclear installation which uses said reactor unit and method of fitting up such an installation. Said installation includes mainly a reactor unit (2) which constitutes a shiftable module formed by a casing (7) and a stand (8), by a container unit (1) designed to accommodate the reactor unit (2) and by a module (3) for closing the container unit (1) and forming, for example, a swimming bath type storing unit for the used nuclear fuel. The installation of the invention may constitute a nuclear boiler which can be transported to the operation site in the form of an integral assembly or in separate components.
051805472	claims	1. A reactor system comprising: conversion means for converting kinetic energy of vapor flow into another form of energy; and a natural-convection boiling-water reactor employing free-surface steam separation, said reactor including: 2. The system of claim 1 wherein said structural section means defines a third group of substantially equal sections arranged annularly about said second group so that each of said sections in said third group is in contact with two other sections of said third group, the sections of said third group having a third average height, said third average height being less than said second average height.
	claims	1. A source-collector device constructed and arranged to generate a radiation beam, the device comprising:a target unit constructed and arranged to present a target surface of plasma-forming material;a laser unit constructed and arranged to generate a beam of radiation directed onto the target surface so as to form a plasma from said plasma-forming material;a contaminant trap constructed and arranged to reduce propagation of particulate contaminants generated by the plasma;a radiation collector comprising a plurality of grazing-incidence reflectors arranged to collect radiation emitted by the plasma and form a beam therefrom; anda filter constructed and arranged to attenuate at least one wavelength range of the beam,wherein the target unit is located within a resonant cavity of the laser unit. 2. A source-collector device constructed and arranged to generate a radiation beam, the device comprising:a target unit constructed and arranged to present a target surface of plasma-forming material;a laser unit constructed and arranged to generate a beam of radiation directed onto the target surface so as to form a plasma from said plasma-forming material;a contaminant trap constructed and arranged to reduce propagation of particulate contaminants generated by the plasma;a radiation collector comprising a plurality of grazing-incidence reflectors arranged to collect radiation emitted by the plasma and form a beam therefrom; anda filter constructed and arranged to attenuate at least one wavelength range of the beam wherein the filter comprises a grazing-incidence reflector having a diffraction grating formed thereon. 3. A source-collector device constructed and arranged to generate a radiation beam, the device comprising:a target unit constructed and arranged to present a target surface of plasma-forming material;a laser unit constructed and arranged to generate a beam of radiation directed onto the target surface so as to form a plasma from said plasma-forming material;a contaminant trap constructed and arranged to reduce propagation of particulate contaminants generated by the plasma;a radiation collector comprising a plurality of grazing-incidence reflectors arranged to collect radiation emitted by the plasma and form a beam therefrom; anda filter constructed and arranged to attenuate at least one wavelength range of the beam wherein the filter comprises a diffraction grating formed on the grazing incidence reflectors of the radiation collector. 4. A device manufacturing method, comprising:directing a laser beam onto a target surface having a plasma-forming material thereon to form a plasma;trapping particulate contaminants emitted by the plasma;collecting radiation emitted by the plasma and forming the radiation into a beam;filtering the beam to attenuate at least one range of wavelengths;patterning the beam of radiation with a pattern in its cross-section; andprojecting the patterned beam of radiation onto a target portion of a substrate. 5. A lithographic apparatus, comprising:a source-collector device constructed and arranged to generate a radiation beam, the device comprisinga target unit constructed and arranged to present a target surface on which a plasma-forming material is present;a laser unit constructed and arranged to generate a beam of radiation directed onto the target surface so as to form a plasma from said plasma-forming material;a contaminant trap constructed and arranged to reduce propagation of particulate contaminants generated by the plasma;a radiation collector comprising a plurality of grazing-incidence reflectors arranged to collect radiation emitted by the plasma and form a beam therefrom; anda filter constructed and arranged to attenuate at least one wavelength range of the beam;a support configured to support a patterning device, the patterning device being configured to impart the beam of radiation with a pattern in its cross-section;a substrate table configured to hold a substrate; anda projection system configured to project the patterned beam onto a target portion of the substrate. 6. A radiation collector comprising a plurality of grazing-incidence reflectors arranged to collect radiation emitted by a plasma and form a beam therefrom; anda filter constructed and arranged to attenuate at least one wavelength range of the beam, the filter comprising a diffraction grating formed on the grazing incidence reflectors of the collector with grooves oriented parallel to an optical axis of the radiation collector. 7. A radiation source comprising:a bath constructed and arranged to contain a fuel for use as a plasma-forming material; anda wheel constructed an arranged to be at least partially immersed in, and rotatable within, said fuel, such that a rim of the wheel may be immersed, in use, in the fuel, the wheel being constructed and arranged to present a surface of the rim as a target for a radiation beam;wherein a surface of the rim is curved across a width of the rim. 8. A source-collector device constructed and arranged to generate a radiation beam, comprising:a first chamber and a second chamber, wherein gas, in use, is allowed to pass from one of the first chamber and second chamber to the other of the first chamber and second chamber;the first chamber housing a plasma formation location and having a gas inlet for introducing gas into the first chamber and a gas outlet for removing gas from the first chamber and configured and arranged to produce a flow rate of gas through the first chamber between 15 slm and 200 slm;the second chamber housing a grazing incidence radiation collector arranged to collect radiation generated, in use, at the plasma formation location, and to form a beam therefrom;the source-collector device further comprising a contaminant trap constructed and arranged to reduce propagation of particulate contaminants generated at the plasma formation location to the grazing incidence radiation collector, the contaminant trap being located in-between the plasma formation location and the grazing incidence radiation collector;the first chamber being arranged, in use, to contain gas at a first pressure, and the second chamber being arranged, in use, to contain gas at a second pressure, lower than the first pressure.
	description	This application claims the benefit of the priority date of Japanese Patent Application No. 2015-188850 filed on Sep. 25, 2015. All of the contents of Japanese Patent Application No. 2015-188850 filed on Sep. 25, 2015 are incorporated by reference herein. The present invention relates to an X-ray microscope, and particularly relates to an X-ray microscope using a Kirkpatrick-Baez mirror. An X-ray microscope is an imaging optical system using electromagnetic wave having an extremely short wavelength, and has, in principle, a sub-nm high resolution significantly higher than that of an optical microscope. The high transmission power of an X-ray allows observation of a three-dimensional tomographic image of a thick sample, which is difficult with a transmissive electron microscope. In addition, basically, the X-ray microscope does not need vacuum formation, and thus, is suitable for observation in an environment (for example, an atmosphere of water solution and gas) in which in-situ measurement is required. In addition, not only electron density distribution but also a local coupling state and element distribution can be acquired by combining X-ray analysis technologies such as fluorescence X-ray analysis and X-ray absorption spectroscopy. The X-ray microscope, which has such various advantages, is expected to be used in various scientific fields. Examples of promised candidates for an imaging element in the X-ray microscope include a Fresnel zone plate, an X-ray refraction lens, a Kirkpatrick-Baez (KB) mirror, and a Wolter mirror. The Fresnel zone plate and the X-ray refraction lens can be sufficiently accurately manufactured to achieve a sub-50-nm resolution. However, the Fresnel zone plate and the refraction lens are not suitable for multicolor imaging because of chromatic aberration occurring due to diffraction. The KB mirror employs total reflection and thus does not suffer chromatic aberration. However, it is difficult to satisfy the Abbe sine condition with single reflection in an grazing-incidence optical system such as the KB mirror, and accordingly, coma occurs, which leads to decrease of the resolution and the field of view (FOV). The Wolter mirror, which solves chromatic aberration and coma, is an excellent X-ray imaging system. However, even when the state-of-the-art ultraprecise fabrication technology is used, it is difficult to fabricate the Wolter mirror at a shaping accuracy (order of 1 nm) necessary for achieving a resolution at diffraction limit because the Wolter mirror has a mirror surface formed of an ellipsoid surface and a hyperboloid surface disposed on a tubular inner surface. Thus, wavefront aberration in the Wolter mirror due to shaping error is a serious problem that currently cannot be avoided, and there has been no report so far that the mirror is produced at a shaping accuracy sufficient to achieve high resolution performance (100 nm or less). Examples of an X-ray optical system using the KB mirror include an optical system (Advanced KB mirror) using four grazing-incidence total reflection X-ray mirrors of a horizontal elliptical mirror, a vertical elliptical mirror, a horizontal hyperbolic mirror, and a vertical hyperbolic mirror as disclosed in JP-A-2013-221874. In this optical system, a horizontal stage and a vertical stage are disposed along the optical axis direction of an X-ray, the horizontal elliptical mirror and the horizontal hyperbolic mirror are provided on the horizontal stage in a finely adjustable manner, and the vertical elliptical mirror and the vertical hyperbolic mirror are provided on the vertical stage in a finely adjustable manner. The optical system includes a mirror manipulator that sets a front-rear positional relation between the horizontal elliptical mirror and the horizontal hyperbolic mirror and a front-rear positional relation between the vertical elliptical mirror and the vertical hyperbolic mirror to be the same in the optical axis direction, and an off-line alignment monitoring means that provides a reference for fine adjustment so that the horizontal postures of the horizontal elliptical mirror and the horizontal hyperbolic mirror and the vertical postures of the vertical elliptical mirror and the vertical hyperbolic mirror are ideal within the margin of error. The X-ray optical system disclosed in JP-A-2013-221874 achieves scaling up and down of an X-ray of 2 keV or higher at a high resolution of 200 nm or less without aberration. However, a Kirkpatrick-Baez (KB) mirror type X-ray microscope allows various kinds of improvement. Unless a problem that cannot be ignored when it is assumed that the X-ray microscope is widely spread and used in various scientific fields is solved, in other words, unless the length of an X-ray microscope device is within two to three meters, it is needed to prepare a facility, for example, a corridor width and an entrance width of which are specially designed to be large to convey the X-ray microscope. When the X-ray microscope is larger than this size, wide use in existing research facilities or the like is hampered for the X-ray microscope even with excellent performance such as a resolution. The present invention is intended to provide an X-ray microscope that has a size small enough to be brought into a room and can be widely used. An X-ray microscope according to the present invention which solves the above problem comprises an X-ray source, a sample holding part, a Kirkpatrick-Baez mirror having a reflection concave surface (that is hereinafter referred to as a “concave KB mirror”), a Kirkpatrick-Baez mirror having a reflection convex surface (that is hereinafter referred to as a “convex KB mirror”), and a light receiving part located at a position in an imaging relation to a position of the sample holding part in this order. Although described later in detail, in the X-ray microscope according to the present invention, the concave KB mirror is disposed on a side closer to the sample holding part, and the convex KB mirror is disposed on a side closer to the light receiving part. Thus, the distance (front-side focal distance) between the position of the principal plane of a lens system and the sample holding part can be reduced as compared to conventional cases. Accordingly, it is possible to achieve an X-ray microscope in which the rear-side focal distance as the distance between the position of the principal plane of the lens system and the light receiving part can be significantly shortened when it is assumed that the magnification is approximately same as that of a conventional optical system, and that has a length of two to three meters or less. In the X-ray microscope, it is preferred that the reflection concave surface of the concave KB mirror includes an elliptical curve, and the sample holding part is located at a focal position of the ellipse. In the X-ray microscope, it is preferred that the reflection convex surface of the convex KB mirror includes one curved line of a hyperbolic curve that is composed of the one curved line and the other curved line, and the light receiving part is located at a focal position of the other curved line side of focal positions of the hyperbolic curve. In the X-ray microscope, it is preferred that a distance between the concave KB mirror and the light receiving part is longer than a distance between the convex KB mirror and the light receiving part. In the X-ray microscope, it is preferred that a principal plane of an imaging system including the convex KB mirror and the concave KB mirror is located between the sample holding part and the concave KB mirror. In the X-ray microscope, it is preferred that a distance between the position of the sample holding part and the position of the light receiving part is 2.5 m or less. In the X-ray microscope, it is preferred that at least the two convex KB mirrors and at least the two concave KB mirrors are provided, a normal of one of the convex KB mirrors and a normal of the other of the convex KB mirrors are non-parallel to each other, and a normal of one of the concave KB mirrors and a normal of the other of the concave KB mirrors are non-parallel to each other. In the X-ray microscope, it is preferred that a shortest distance between the sample holding part and the concave KB mirror is 6 mm or more. In the X-ray microscope, it is preferred that at least one of the convex KB mirror and the concave KB mirror is installed so as to be movable in an optical axis direction. In the X-ray microscope, it is preferred that a first concave KB mirror and a second concave KB mirror are provided between the sample holding part and the concave KB mirror, a normal of the concave KB mirror and a normal of the first concave KB mirror are non-parallel to each other, and a normal of the convex KB mirror and a normal of the second concave KB mirror are non-parallel to each other. In the X-ray microscope, it is preferred that the first concave KB mirror is located closer to the sample holding part than the second concave KB mirror, a reflection concave surface of the first concave KB mirror includes a hyperbolic curve, and a reflection concave surface of the second concave KB mirror includes an elliptical curve. An X-ray microscope according to the present invention includes an X-ray source, a sample holding part, a concave KB mirror, a convex KB mirror, and a light receiving part located at a position in an imaging relation to the position of the sample holding part in this order along an optical axis, and thus can have a reduced rear-side focal distance of an optical system while the magnification is maintained. Accordingly, a conventional X-ray microscope can be made to have a size that can be brought into a room, in other words, a widely usable size, thereby achieving high industrial applicability due to increased use of X-ray microscopes in various scientific fields. An X-ray microscope in an embodiment of the present invention will be described below. An X-ray microscope according to the present invention includes at least one of each of an X-ray source, a sample holding part, a concave KB mirror, a convex KB mirror, and a light receiving part located at a position in an imaging relation to the position of the sample holding part in this order along an optical axis. With this configuration, the rear-side focal distance of an optical system can be reduced while the magnification of the X-ray microscope is held. The following sequentially describes the X-ray source, the sample holding part, the concave KB mirror, the convex KB mirror, and the light receiving part, which are basic requirements of the present Invention. 1. X-Ray Source Any device having a function to emit an X-ray is applicable, but a small X-ray tube for laboratory usage is preferably used, and alternatively, a synchrotron radiation facility (such as SPring-8) can be used. Similarly to a normal optical microscope using a visible light ray, the X-ray microscope preferably uses Kohler illumination or critical illumination, and it is desirable to use a light source capable of achieving these illuminations. It is difficult to perform complicated Kohler illumination in an X-ray region, and thus, typically, critical illumination is performed, or an X-ray approximately having the range of the field of view is emitted as appropriate. Accordingly, a sample as an observation target can be irradiated with an X-ray having uniform intensity, and clear imaging with little blurring can be obtained. The energy of an X-ray is not particularly limited, and a soft X-ray, an X-ray, and a hard X-ray can be used, but it is desirable to use an X-ray or a hard X-ray having energy of 2 keV or higher to obtain a high resolution of 200 nm or less. 2. Sample Holding Part The sample holding part may be any instrument having a function to hold a sample as an observation target on the optical path of an X-ray. The sample holding part may be, for example, a table on which a sample is simply placed, two dielectric flat plates for sandwiching a sample therebetween, a dielectric single-plate for fixing a sample, a frame for hanging a sample, or a container for holding a liquid sample. An instrument having any configuration having a function to hold a sample on the optical path of an X-ray may be used as the sample holding part. The material of the sample holding part is not particularly limited, but it is desirable to use a material that transmits an X-ray when the X-ray is directly incident on the sample holding part. It is also desirable to select a material to which accumulation of electric charge due to X-ray irradiation is unlikely to occur. 3. KB Mirror The reflection surface of the above-described Wolter mirror is formed by a rotational locus of a curved line, but, a KB mirror used in the present invention is a one-dimensional condensing mirror having curvature only in one direction. The KB mirror has a shape close to a flat plate, and thus it is easier to fabricate a surface thereof as compared to the Wolter mirror. The incident angle (angle between the surface of the KB mirror and the optical axis) of an X-ray by the KB mirror is typically several milliradian approximately, and 80 to 90% approximately of an incident X-ray is reflected. When the incident angle is large, a larger fraction of the X-ray transmits the KB mirror. It is sufficient that a part of the entire of one KB mirror where the reflection surface is formed in a curved surface extends across a range irradiated with an X-ray. However, it is preferable to form a mirror shape continuously for a long interval in the other direction orthogonal to the one direction in which the KB mirror has the curvature so that a surface not irradiated with an X-ray can be used by sliding the KB mirror when the irradiated part degrades while the KB mirror is used. For example, the length of the mirror formation interval in the other direction is preferably two to five times, more preferably two to ten times, further preferably two to fifteen times larger than the length of a mirror formation interval in the one direction. The accuracy of the shape (JIS B0182 Basics 306) of the reflection surface of the KB mirror is preferably 5 nm or less, more preferably 3 nm or less, further preferably 1 nm or less. The surface roughness (JIS B0091: Rms) of the reflection surface is preferably 0.5 nm or less, more preferably 0.3 nm or less, further preferably 0.1 nm or less. Typically, the term “KB mirror” indicates a pair of mirrors, the directions (for example, X and Y directions) of the normals of which are orthogonal to each other. However, a “KB mirror” used herein indicates a single (one) X-ray mirror. Thus, the X-ray microscope according to the present invention includes a case in which a single mirror is used, and also includes a case in which a plurality of mirrors, the directions of the normals of which are different from one another are included. In the case in which a plurality of mirrors, the directions of the normals of which are different from each other are included, the normals are desirably angled from each other at a value by dividing 360° by “the number of mirrors”×2. For example, when imaging is achieved by using two KB mirrors, the normals of the mirrors are preferably angled at 360°/(2×2)=90° from each other. The X-ray microscope according to the present invention is applicable to a case in which only one pair of one convex KB mirror and one concave KB mirror is included, and also applicable to a case in which a plurality of pairs of a convex KB mirror and a concave KB mirror are used. The X-ray microscope according to the present invention only needs to include at least one pair of one convex KB mirror and one concave KB mirror, and may additionally include one or a plurality of pairs of a first concave KB mirror and a second concave KB mirror. 3.1. Concave KB Mirror As described above, the X-ray microscope according to the present invention includes at least the concave KB mirror and the convex KB mirror. Among these KB mirrors, the concave KB mirror is disposed on a side closer to the sample holding part. The curvature of a reflection concave surface of the concave KB mirror and the curvature distribution thereof are not particularly limited, but the reflection concave surface may have, for example, an arc shape, an elliptical shape, a hyperbolic shape, or a parabolic shape. Among these shapes, it is preferable to have the elliptical shape to obtain a favorable imaging characteristic. The sample holding part is preferably disposed at the focal position of an elliptical mirror, in particular, the position of a focal position close to the sample holding part. 3.2. Convex KB Mirror As described above, the X-ray microscope according to the present invention includes at least the concave KB mirror and the convex KB mirror, and the convex KB mirror is disposed on the side closer to the light receiving part. A sectional shape of a reflection convex surface is not particularly limited, but may be, for example, an arc shape, an elliptical shape, a hyperbolic shape, or a parabolic shape. Among these shapes, it is desirable to have the hyperbolic shape to obtain a favorable imaging characteristic. The reflection convex surface includes one curved line of a hyperbolic curve that is composed of the one curved line and the other curved line, and the light receiving part is preferably located at one of the focal positions of the hyperbolic curve, which is closer to the other curved line. 4. Light Receiving Part The light receiving part in the present invention is a member configured to receive an imaged X-ray image through the convex KB mirror and the concave KB mirror of the X-ray microscope according to the present invention. The receiving member is typically an array sensor, and preferably a two-dimensional array sensor. Examples of the two-dimensional array sensor include a CCD element and a CMOS element. The pixel pitch of the array sensor is preferably 20 μm or less, more preferably 9 μm or less, further preferably 3 μm or less to clearly receive the imaged X-ray image. The light receiving part may be a diffusion plate configured to convert a received X-ray into light having a wavelength longer than that of the X-ray, typically an ultraviolet ray or a visible light ray. Examples of the diffusion plate include a substrate containing a fluorescence material. X-ray imaging at the light receiving part can be acquired by imaging, through a visible light ray lens, light diffused through the diffusion plate and performing image capturing through an array sensor, preferably a two-dimensional array sensor such as a CCD element or a CMOS element. The following describes an X-ray microscope in Embodiment 1 of the present invention. FIG. 1 is a perspective view of an optical system of an X-ray microscope in Embodiment 1. In FIG. 1, an X-ray 2 emitted from an X-ray source 1 as the origin of the X-ray optical system is incident on a sample holding part 3 holding a sample as a microscopic observation target. The X-ray 2 (including light emission and scattering light) having transmitted through the sample holding part 3 is reflected at, in the following order, the reflection concave surface of a concave KB mirror 4, the reflection convex surface of a convex KB mirror 5, the reflection concave surface of a concave KB mirror 6 having a normal orthogonal to the normal of the concave KB mirror 4, and the reflection convex surface of a convex KB mirror 7 having a normal orthogonal to the normal of the convex KB mirror 5. The X-ray 2 then arrives at a light receiving part 8 located at a position in an imaging relation to the position of the sample holding part 3. In the example illustrated in FIG. 1, an elliptical focal position and a hyperbolic focal position coincide with each other. Thus, light emitted from the reflection concave surface of the concave KB mirror 4 all arrives at the hyperbolic focal position through a total of two times of reflection at the reflection concave surface and the reflection convex surface of the convex KB mirror 5. Accordingly, all optical paths have equal lengths, and thus the X-ray condenses without aberration. The condensing is also possible when the elliptical focal position and the hyperbolic focal position do not coincide with each other. The concave KB mirror 4 and the convex KB mirror 5 may be each any other concave or convex surface mirror such as a cylindrical surface mirror, but it is desirable that an elliptical concave surface mirror is used as the concave KB mirror 4 and a hyperbolic concave surface mirror is used as the convex KB mirror 5 as illustrated in FIG. 1 to reduce spherical aberration. A “condensing” condition and a “coma suppression” condition are needed for imaging of the X-ray 2 at the light receiving part 8, and the X-ray needs to be reflected an even number of times as illustrated in FIG. 1 to achieve coma suppression. The concave KB mirror 4 has elliptical curvature in an X axis direction but no curvature in a Y axis direction, and accordingly has a function to condense an X-ray in the X axis direction. The convex KB mirror 5 has hyperbolic curvature in the X axis direction but no curvature in the Y axis direction, and accordingly has a function to change the progressing direction of an X-ray only in the X axis direction. The concave KB mirror 6 has elliptical curvature in the Y axis direction but no curvature in the X axis direction, and accordingly has a function to condense an X-ray in the Y axis direction. The convex KB mirror 7 has hyperbolic curvature in the Y axis direction but no curvature in the X axis direction, and accordingly has a function to change the progressing direction of an X-ray only in the Y axis direction. When a magnification in the X axis direction by the concave KB mirror 4 and the convex KB mirror 5 is equal to a magnification in the Y axis direction by the concave KB mirror 6 and the convex KB mirror 7, a sample image without distortion can be obtained on the light receiving part 8. When the magnification in the X axis direction is not equal to the magnification in the Y axis direction, a sample image without distortion can be obtained by performing correction through expansion and contraction of a sample image obtained on the light receiving part 8 by an optical system of, for example, visible light or on electronic information, so that the magnification in the X axis direction is equal to the magnification in the Y axis direction. FIG. 2 illustrates a geometric pattern diagram (upper part) of the X-ray optical system illustrated in FIG. 1, and illustrates, for reference, a visible light ray optical system (lower part) having a geometric optical function equivalent to an optical element used in the X-ray optical system. In the upper part of FIG. 2, to facilitate understanding, the concave KB mirror 6 and the convex KB mirror 7 for condensing in the Y axis direction are not illustrated. In the upper part of FIG. 2, the X-ray 2 emitted from the X-ray source 1 as the origin of the X-ray optical system is incident on the sample holding part 3 holding a sample as a microscopic observation target. The X-ray 2 having transmitted the sample holding part 3 is reflected at the reflection concave surface of the concave KB mirror 4 and the reflection convex surface of the convex KB mirror 5 in this order, and arrives at the light receiving part 8 located at a position in an imaging relation to the position of the sample holding part 3. An image of the sample can be determined by specifying the intensity distribution of the X-ray detected at the light receiving part 8. The principal plane of a condenser optical system composed of the concave KB mirror 4 and the convex KB mirror 5 is located at a position illustrated with a dotted line in FIG. 2. There is a relation indicated by Expression (1) below among a distance (front-side focal distance) f between the sample holding part 3 and the principal plane, a distance (rear-side focal distance) L between the principal plane and the light receiving part 8, and a magnification Mag of the condenser optical system.Mag=L/f (1) Expression (1) is used in description of an optical system reduction mechanism of the X-ray microscope according to the present invention in Embodiments 3 to 5 to be described later. The distance (L+f) between the position of the sample holding part 3 and the position of the light receiving part 8 is preferably 2.5 m or less. This distance is more preferably 2.0 m or less, and further preferably 1.8 m or less. To achieve this, the distance f desirably has a smaller value and is preferably 6 mm or more, more preferably 8 mm or more, further preferably 10 mm or more to have an appropriate working distance between the sample holding part 3 and the concave KB mirror 4. The value of f has an upper limit of, for example, 40 mm or less, more preferably 20 mm or less, and further preferably 16 mm or less. FIG. 3 is a perspective view of the optical system of the X-ray microscope in Embodiment 2. The X-ray microscope in Embodiment 2 is different from the X-ray microscope in Embodiment 1 in that neither concave KB mirror 4 nor convex KB mirror 5 is provided in Embodiment 2. The other configuration is same as that of the X-ray microscope in Embodiment 1. To evaluate an imaging characteristic of the X-ray microscope in Embodiment 2, a point spread function (PSF) that is distribution of an X-ray intensity at the light receiving part 8 is calculated under a condition that the X-ray source is an ideal point light source. FIG. 4 illustrates this point spread function. In FIG. 4, the horizontal axis represents a scale (centered at 500 nm) on the Y axis, and the vertical axis represents the X-ray intensity at the light receiving part 8. As illustrated in FIG. 4, a central peak has a half width (FWHM) of 38 nm, which indicates that a high space resolution is provided. Detailed conditions used in the calculation are as follows. Mag: 181 times L: 0.7 m f: 4.0 mm NA of a lens system of the concave KB mirror 6 and the convex KB mirror 7: 1.3×10−3 X-ray optical path simulation was performed, assuming an X-ray microscope in which the concave KB mirror 4 and the convex KB mirror 5 are not provided as in Embodiment 2. FIG. 5 illustrates an X-ray optical path up to a place separated by 120 mm from the sample holding part (zero point on the horizontal axis). The concave KB mirror 6 and the convex KB mirror 7 are disposed in this order halfway through the X-ray optical path. FIG. 6 illustrates an X-ray optical path of an optical system in which two concave KB mirrors (a concave KB mirror 19 and a concave KB mirror 20) as in a conventional case are disposed, in place of the concave KB mirror 6 and the convex KB mirror 7, at positions same as the positions of the concave KB mirror 6 and the convex KB mirror 7 described in Embodiment 3 in the direction of the optical axis. X-ray optical path simulation was performed, assuming an X-ray microscope in which the concave KB mirror 4 and the convex KB mirror 5 are not provided as in Embodiment 2. FIG. 7 illustrates an X-ray optical path up to a place separated by 120 mm from the sample holding part (zero point on the horizontal axis). The concave KB mirror 6 and the convex KB mirror 7 are disposed in this order at a position different from the example of Embodiment 3 and halfway through the X-ray optical path. FIG. 8 illustrates an X-ray optical path of an optical system in which two concave KB mirrors (the concave KB mirror 19 and the concave KB mirror 20) as in a conventional case are disposed, in place of the concave KB mirror 6 and the convex KB mirror 7, at positions same as the positions of the concave KB mirror 6 and the convex KB mirror 7 described in Embodiment 4 in the direction of the optical axis. X-ray optical path simulation was performed, assuming an X-ray microscope in which the concave KB mirror 4 and the convex KB mirror 5 are not provided as in Embodiment 2. FIG. 9 illustrates an X-ray optical path up to a place separated by 120 mm from the sample holding part (zero point on the horizontal axis). The concave KB mirror 6 and the convex KB mirror 7 are disposed in this order at a position different from the examples of Embodiments 3 and 4 and halfway through the X-ray optical path. FIG. 10 illustrates an X-ray optical path of an optical system in which two concave KB mirrors (the concave KB mirror 19 and the concave KB mirror 20) as in a conventional case are disposed, in place of the concave KB mirror 6 and the convex KB mirror 7, at positions same as the positions of the concave KB mirror 6 and the convex KB mirror 7 described in Embodiment 5 in the direction of the optical axis. FIG. 11 is a perspective view of an optical system of an X-ray microscope in Embodiment 6 of the present invention. The X-ray microscope in Embodiment 6 is different from the X-ray microscope in Embodiment 1 in that a first concave KB mirror 21 and a second concave KB mirror 22 are used for condensing in the X axis direction in Embodiment 6, whereas the concave KB mirror 4 and the convex KB mirror 5 are used for condensing in the X axis direction in Embodiment 1. The other configuration is same as that of the X-ray microscope in Embodiment 1. The first concave KB mirror 21 and the second concave KB mirror 22 each have curvature in the X axis direction but no curvature in the Y axis direction, and accordingly has a function to condense an X-ray in the X axis direction. The concave KB mirror 6 has curvature in the Y axis direction but no curvature in the X axis direction, and accordingly has a function to condense an X-ray in the Y axis direction. The convex KB mirror 7 has curvature in the Y axis direction but no curvature in the X axis direction, and accordingly has a function to change the progressing direction of an X-ray only in the Y axis direction. The X-ray microscope described above in Embodiment 1 has a high effect of increasing the magnification for a sample, but the magnification is too high when a mirror has a large NA. In particular, a mirror (in Embodiment 1, the concave KB mirror 4 and the convex KB mirror 5 as a pair of mirrors for condensing in the X axis direction) close to a sample has a large NA, and thus the magnification is too high. In practical use, longitudinal and transverse (in the X axis direction and the Y axis direction) magnifications are desirably equal to each other. In the X-ray microscope in Embodiment 6, when a pair of mirrors (the first concave KB mirror 21 and the second concave KB mirror 22) on a side closer to a sample are both concave mirrors, an appropriate magnification can be obtained in the X axis direction so that the longitudinal and transverse magnifications of the X-ray microscope are adjusted to be equal to each other. More preferably, it is desirable that the reflection concave surface of the first concave KB mirror 21 located at a place closer to the sample holding part than the second concave KB mirror 22 includes a hyperbolic curve, and the reflection concave surface of the second concave KB mirror 22 includes an ellipse. In the example illustrated in FIG. 11, the elliptical focal position of the second concave KB mirror 22 and the hyperbolic focal position of the first concave KB mirror 21 coincide with each other, and thus, similarly to Embodiment 1, X-rays emitted from a single point on a sample condense to a single point on an image plane. Thus, all optical paths from the sample to the image plane have equal lengths, and accordingly, a sharp image can be obtained. FIG. 12 illustrates an X-ray optical path (X-axis projection) near the first concave KB mirror 21 and the second concave KB mirror 22 of the X-ray microscope in Embodiment 6. FIG. 13 illustrates an X-ray optical path (Y-axis projection) near the concave KB mirror 6 and the convex KB mirror 7 of the X-ray microscope in Embodiment 6. The X-ray microscope has condensing performance as listed in Table 1 below. TABLE 1First concave KB mirror 21Second concave KB mirror 21Concave KB mirror 6Convex KB mirror 7CurveTypehyperbolicellipticalellipticalhyperbolicEquationx2/a2 − y2/b2 = 1x2/a2 + y2/b2 = 1x2/a2 + y2/b2 = 1x2/a2 − y2/b2 = 1a0.095 m1.573 m0.0845 m1.479 mb4.075 × 10−4 m5.619 × 10−3 m1.254 × 10−3 m1.853 × 10−3 mProspective angle16.86 mrad14.50 mrad15.68 mrad5.22 mradNA5.057 × 10−35.043 × 10−3Focal distance f21.47 mm22.12 mmMagnification144.6 times140.4 timesL + f3127 mm(Discussion) In FIGS. 5 to 10, each position of the principal plane of the lens system is illustrated with a dotted line. Comparison of FIG. 5 (Embodiment 3) and FIG. 6 (Comparative Embodiment 1) indicates that the position of the principal plane of a lens is separated from the sample holding part by 70 mm (refer to the value of f in FIG. 6) in Comparative Embodiment 1, but the position of the principal plane of a lens is separated from the sample holding part by 12 mm (refer to the value of fin FIG. 5) in Embodiment 3, which is an extremely reduced value. When the value of f is small, designing with a reduced value of L is possible on an assumption that the magnification Mag of the microscope is approximately maintained, as indicated by the above-described Expression (1). The value of L is 12.6 m in the example illustrated in FIG. 6, but the value of L is 2.0 m in the example illustrated in FIG. 5, which is an extremely reduced value. Thus, the X-ray microscope can be designed to be small enough to be brought into a laboratory. Similarly, comparison of FIG. 7 (Embodiment 4) and FIG. 8 (Comparative Embodiment 2) indicates that the value of f is reduced from 22 mm to 4.0 mm and the position of the principal plane is located closer to the position of the sample holding part 3. Accordingly, the value of L is 3.8 m in the example illustrated in FIG. 8, but the value of L is 0.7 m in the example illustrated in FIG. 7, which is an extremely reduced value. Thus, the X-ray microscope can be designed to be small enough to be brought into a laboratory. Similarly, comparison of FIG. 9 (Embodiment 5) and FIG. 10 (Comparative Embodiment 3) indicates that the value of f is reduced from 43 mm to 11 mm and the position of the principal plane is located closer to the position of the sample holding part 3. Accordingly, the value of L is 7.7 m in the example illustrated in FIG. 10, but the value of L is 2.0 m in the example illustrated in FIG. 9, which is an extremely reduced value. Thus, the X-ray microscope can be designed to be small enough to be brought into a laboratory. The Embodiments 3 to 5 describe above effects of the present invention in an example with a one-dimensional condensing optical system. As described in Embodiment 1, a pair of a concave KB mirror and a convex KB mirror is used in each of the X axis direction and the Y axis direction to achieve two-dimensional condensing. For example, when both of the mirror system in Embodiment 3 (FIG. 5) and a mirror system obtained by rotating the mirror system in Embodiment 4 (FIG. 7) about the optical axis by 90° are used, a two-dimensional condenser optical system can be formed without interference between the mirrors. The rear-side focal distance (the value of L) of the mirror system in FIG. 5 is 2.0 m, and the rear-side focal distance (the value of L) of the mirror system in FIG. 7 is 0.7 m. These rear-side focal distances can be made equal to each other by adjusting, for example, the NA value and magnification of the mirror system in FIG. 7. In this adjustment, the magnification in the X direction and the magnification in the Y direction are different from each other in some cases, but distortion of the image plane can be optically or electrically corrected as described in the above-described embodiment. In any case, an extremely small X-ray microscope including a two-dimensional condenser optical system, the rear-side focal distance of which is 2.0 m, can be achieved. The above-described Embodiment 6 is an X-ray microscope in which the concave KB mirror 6 and the convex KB mirror 7 are used for condensing in the Y axis direction, and the first concave KB mirror 21 and the second concave KB mirror 22 are used for condensing in the X axis direction. As understood from the above-described Table 1, since the first concave KB mirror 21 and the second concave KB mirror 22, which are located close to the position of the sample holding part 3, each has a concave reflection surface in the X-ray microscope according to the present embodiment, the position of the principal plane can be separated from a sample, and the magnification in the X axis direction can be reduced. Accordingly, a microscopic image, the magnification in the X axis direction and the magnification in the Y axis direction of which are close to each other, in other words, an aspect ratio of which is close to one can be obtained. The distance (L+f) between the position of the sample holding part 3 and the position of the light receiving part 8 is 3127 mm, which indicates downsizing of the entire device. As described above, the principal plane needs to be separated from the position of the sample holding part 3 to obtain a certain magnification in a conventional X-ray microscope, but in the X-ray microscope according to the present invention, the position of the principal plane is located largely closer to the position of the sample holding part 3, and accordingly, an X-ray microscope with the value of L reduced enough to be brought into a laboratory can be provided. The X-ray microscope according to the present invention can have a reduced rear-side focal distance of the optical system while the magnification is maintained. The present invention allows a conventional X-ray microscope not having a widely usable size, in other words, a size of which cannot be brought into a room, to have a widely usable small size, and has high industrial applicability by the use of an X-ray microscope in various scientific fields. 1: an X-ray source 2: an X-ray 3: a sample holding part 4: a concave KB mirror 5: a convex KB mirror 6: a concave KB mirror 7: a convex KB mirror 8: a light receiving part 11: a visible light source 12: a visible light ray 13: a sample holding part 14: a visible light convex lens 15: a visible light concave lens 18: a light receiving part 19: a concave KB mirror 20: a concave KB mirror 21: a first concave KB mirror 22: a second concave KB mirror
	claims	1. A device for generating extreme ultraviolet radiation and soft x-ray radiation with a gas discharge operated on the left branch of the Paschen curve, the device comprising:a discharge chamber (10) of a predetermined gas pressure;two electrodes (11, 12) arranged in the discharge chamber (10), wherein the two electrodes have an opening (14, 15), respectively, wherein the openings have coinciding symmetry axes (13);wherein the two electrodes, in the course of a voltage increase (16) upon reaching a predetermined ignition voltage (Uz), generate a plasma (17) located in the area between the openings (14, 15);a triggering electrode (19) arranged in a space (23) adjoining a first one of the electrodes (11), wherein the triggering electrode triggers an ignition of the plasma (17) for producing the radiation (17′) by gas discharge;an energy storage device for supplying stored energy into the plasma (17) with the two electrodes (11, 12);wherein the triggering electrode (19) is arranged outside of a particle beam being formed on the symmetry axes (13) or is provided with a shielding (35) preventing the particle beam from impinging on the triggering electrode (19). 2. The device according to claim 1, wherein the triggering electrode (19) is arranged on the symmetry axes of the openings (14, 15) of the electrodes (11, 12), wherein the shielding is an insulator provided on an end face (34) of the triggering electrode facing the openings (14, 15) of the electrodes. 3. The device according to claim 2, wherein the insulator is a layer applied onto the end face (34) of the triggering electrode (19). 4. The device according to claim 2, wherein the insulator is a member that is sunk into the end face (34) of the triggering electrode (19). 5. The device according to claim 4, wherein the insulator has a recess (36) with a cross-section matched to the particle beam. 6. The device according to claim 5, wherein the recess (36) of the insulator tapers conically. 7. The device according to claim 1, wherein the triggering electrode (19) is completely insulated at least relative to the space (23) adjoining the first electrode (11). 8. The device according to claim 7, wherein the shielding (35) of the triggering electrode (19) has a residual conductivity that dissipates surface charges but prevents a discharge-affecting current flow between a second one of the two electrodes (12) and the triggering electrode (19). 9. The device according to claim 8, wherein the triggering electrode (19) is formed as a hollow cylinder surrounding the symmetry axes. 10. The device according to claim 9, wherein the triggering electrode (19) has a bottom that is facing away from the two electrodes (11, 12), wherein the bottom is embodied as an insulator or is embodied as a metal bottom connected to the potential of one of the electrodes (11, 12) and insulated relative to a remaining part of the triggering electrode (19). 11. The device according to claim 1, wherein the triggering electrode (19) is an annular plate mounted transversely to the symmetry axis (13) of the electrodes (11, 12) in the first electrode (11) or the triggering electrode is at least one electrode pin mounted transversely to the symmetry axis (13) of the electrodes (11, 12) in the first electrode (11). 12. The device according to claim 1, wherein the triggering electrode (19) is mounted in a first one of the electrodes (11) and is insulated relative to the first electrode. 13. The device according to claim 1, wherein the shielding (35) is comprised of a temperature-resistant insulation material. 14. The device according to claim 1, wherein the shielding (35) is connected to the triggering electrode (19) so as to provide excellent thermal conducting. 15. The device according to claim 1, wherein the shielding (35) has a diameter matching at least a diameter of the openings (14, 15) of the two electrodes.
	description	This application is a National Stage of International Application No. PCT/US2013/059445 filed Sep. 12, 2013, and which claims benefit of U.S. Provisional Application No. 61/699,864 filed Sep. 12, 2012, both of which are herein incorporated by reference in their entirety. The present invention relates generally to electric power and process heat generation using of a modular, compact, transportable, hardened nuclear generator rapidly deployable and retrievable, comprising power conversion and electric generation equipment fully integrated within a single pressure vessel housing a nuclear core. Nuclear generators naturally involve nuclear cores that produce decay thermal energy after shut down. Generally, among several factors, the amount of decay thermal energy produced after shutdown is proportional to the fuel power generation history and power density characterizing the nuclear core. To avoid overheating of the nuclear fuel in any location of the core, decay heat energy must be transferred from the core using redundant heat transfer mechanisms generally supported by systems external to the vessel and structures designed to contain the core. These redundant cooling systems comprise complex networks of piping thermal-hydraulically coupling the core to heat exchangers located outside of the vessel containing the core and dedicated to transfer thermal energy from the core to the environment (i.e. an ultimate heat sink). Coolant through these heat exchangers may actively circulate using electrically driven re-circulators (i.e. pumps, blowers) and redundancies are represented using multiple heat exchangers regulated by valves dedicated to route or re-route coolant through relatively complex piping networks. Alternatively, coolant may passively circulate through similarly complex piping networks, thermal-hydraulically coupling the core to extra-core heat exchangers, by gravity-driven natural circulation mechanisms based on the fact that coolant density changes when heated or cooled. Modern nuclear reactors rely on redundant core decay heat removal systems that may be operated passively, actively or a combination of both. To remove decay thermal energy, reactor designs adopting “active” safety features extensively rely on electric power for the core to be maintained at safe temperatures after shutdown. To ensure safe operation and decay thermal energy removal at all times, these designs require electric power provided by connection to a minimum of two off-site power grids, and emergency electric power produced by dedicated redundant on-site emergency diesel generators (EDGs). Some types of passive safety features, on the other hand, solely rely on gravity and large inventory of water generally stored in tanks or water structures positioned at relatively high elevations with respect to the core. Elevation differential between the core and the coolant storage structures is required for the coolant to undergo natural circulation siphoning, and effectively remove decay thermal energy from the core. For passive safety features based on stored coolant, the ability to adequately provide long-term decay heat removal is highly dependent on the coolant inventory and the effectiveness of the gravity-driven core-cooling mechanism under various environmental temperature and humidity conditions. Generally, as environmental temperature increases, the ability to passively generate convective core-cooling becomes gradually impaired. As a result passive decay heat removal based on stored coolant inventories is best suitable for nuclear generators operating in mild climates. As passive and active safety systems generally develop externally to the vessel housing the core, the result is a complex system of redundant piping, valves, heat exchangers, as well as pumps/blowers and ancillary power and control cabling networks (i.e. required to provide motive-electric power and control for active systems). The complex system of piping and thermal-hydraulic (i.e. heat exchangers) and electric equipment (i.e. pumps) dedicated to remove thermal energy from the core is generally defined as balance of plant. The balance of plant of most nuclear generators, large and small, induces substantially large plant foot-prints, imposes limitations on the sites at which the nuclear generators can be deployed, and significantly increases the capital cost characterizing nuclear generator installations. Nuclear cores of commercially operating reactors are generally cooled by water and loaded with nuclear fuel elements cladded with materials that oxidize in the presence of high temperature water/steam. As a core may experience overheating due, for example, to loss of coolant, or failure of the active or passive core decay heat removal systems, chemical reactions between cladding materials and water/steam result in the production of hydrogen. Hydrogen then accumulates and eventually self-ignites, thereby posing severe safety challenges. As a result, nuclear power plants are equipped with redundant hydrogen management equipment to, for example, execute controlled ignitions and prevent accumulation of large hydrogen amounts. However, this additional safety feature further adds complexity, increases operating cost and may not be as manageable as demonstrated by several nuclear accidents as, for example, the accident that occurred at the Fukushima Daiichi nuclear station in Japan. The level of redundancies employed to ensure active, passive, or a combination of both safety systems, execute they safety functions are generally the result of probabilistic risk assessments based on postulated design basis accident scenarios. Not all possible accident scenarios are contemplated as the probability for the occurrence of beyond design basis accident scenarios is very low. Unfortunately, despite redundancies and multiple engineered barriers to the escape of radioactivity from the core to the environment, core meltdown, hydrogen explosions, containment breach and large radioactive fall out have occurred even for nuclear generating stations compliant with the most up to date regulatory guidance for safe operation (i.e. Fukushima Daiichi power station), thus demonstrating that catastrophic accidents, as those triggered by beyond design basis accident scenarios, have an unacceptable safety and economic impact even though their probability of occurrence is very low. Beyond design basis accident scenarios may be represented by extreme seismic, tsunami, weather related, terrorist/hostile events. Small modular reactor designs are characterized by smaller, modular and more easily transportable components when compared to large modern reactor designs. However, these components, or modules, cannot operate without first being thermal-hydraulically (and electrically) coupled at the site of deployment. Coupling of these modular components occurs by interconnection with complex networks of piping, valves, passive and/or active core cooling systems (balance of plant), configured outside of the vessel comprising the core. As a result deployment, and installation of an electric station based on small modular reactor designs, requires several months for site preparation, installation of balance of plant equipment, and coupling of all auxiliaries regardless of the size of the small modular reactor. In fact, once small modular reactor systems are coupled, the total small modular reactor-based electric station footprint and emergency evacuation zone remain still substantial, even for small modular reactor designs producing modest or very low power ratings. Once assembled, small modular reactor designs cannot be transported or retrieved and therefore cannot be readily deployed nor they can be retrieved from a site without undergoing disassembly of modular components and several months dedicated to dismantling the balance of plant, with generally lengthy decommissioning procedures for the removal of several separate and potentially radioactive small modular reactor components. In view of the foregoing, there is an ongoing need for a truly transportable, fully operational, compact modular nuclear generator system and method for safely producing electric energy, with the option to provide process heat, capable of safely operating in any climatic conditions, at any site with the ability of safely cope with extreme environmental stressor (including severe seismic and flooding events), and in a manner that inherently reduces the consequences of postulated design basis as well as beyond design basis accident scenarios. In view of the above, a transportable hardened compact modular nuclear generator is disclosed. The disclosed generator is formed by a nuclear core housed in a vessel comprising the integral power conversion and power generation equipment with no need for extra-vessel balance of plant and comprising features that passively ensure core cooling under all accident scenarios, including beyond design basis accident scenarios and design basis attack scenarios. Depending on site-specific electric demand (and process heat requirements), the transportable, hardened, compact modular nuclear generator, for simplicity hereinafter referred to as transportable nuclear generator, may be configured to operate with various core configurations, materials, coolants and moderators, so as to convert thermal energy generated by the core into electricity and process heat using integral power conversion equipment configured to operate with various thermodynamic power cycles (i.e. Brayton, Rankine) and power generation equipment configured to condition voltage and frequency to match site-specific electric requirements. In some configurations, the transportable nuclear generator may provide power ratings from 10 MWt-to-40 MWt (Mega-Watt-thermal), with an efficiency of approximately 45%, when operated with a power conversion module configured to convert thermal energy via gas-Brayton cycle. Under this exemplary configuration, a single transportable nuclear generator represents a power generation unit capable of producing 4.5 MWe-to-18 MWe (Mega-Watt-electric). As the transportable nuclear generator may operate with passive cooling via natural air-circulation across its heat transfer surfaces, it can be clustered with multiple transportable nuclear generator units so as to match site-specific electric and/or process heat demands. As the transportable nuclear generator is easily transportable and retrievable, it is suitable for a variety of applications, for example, it can be utilized for electric power generation and process heat applications in remote areas or grid-unattached locations. Additional applications may include power generation for various land-based or artificial island industrial-processes (mining, oil-gas extraction, military installations), ship propulsion and as rapid grid back-up system at critical bulk power grid interconnections. In one exemplary configuration, the transportable nuclear generator is formed by three main modules: (1) the swappable reactor power module, housing the core, control systems and coolant flow reversing structure, (2) the power conversion module, comprising turbo-machinery equipment, and heat exchangers, and (3) the power generation module, comprising a fast generator-motor, electronic controllers and Uninterruptable Power Sources (i.e. batteries) to be utilized during start-up operations. Once thermal-hydraulically coupled through sealing flanges the three modules form a single hardened vessel passively exchanging thermal energy with the surrounding environment. The rotary equipment forming the turbo-machinery systems of the power conversion module are mechanically coupled to a single shaft also mechanically coupled to the shaft of the rotary components integrated in the generator-motor of the power generation module, thus all of the rotary equipment is matched to rotate at the same speed frictionless using magnetic bearings. Each module may be transported independently, or all three fully assembled into a single vessel that allows the transportable nuclear generator to be readily operational. Fully assembled or in separate modules transport of transportable nuclear generator may be executed in compliance with transportation standards (i.e. utilizing standard transportation equipment). When transported fully assembled, the transportable nuclear generator represents a rapidly deployable and retrievable fully operational electric power generator. In one exemplary configuration, the transportable nuclear generator modules may be coupled using sealing and locking flanges so as to form a single hardened pressure vessel operating horizontally. In another configuration with re-oriented external and internal transportable nuclear generator heat transfer fins, the transportable nuclear generator may operate vertically. All three modules comprise highly integrated heat exchangers formed by internal and external fins configured to provide support to internal components while substantially reinforcing the overall structure by forming multiple internal and external structural ribs. The integral heat exchangers, combined with integral turbo-machinery and generator-motor equipment, allow for operation without need for external balance of plant, thereby substantially decreasing overall footprint, vulnerabilities, and the probability for loss of coolant scenarios. The transportable nuclear generator may employ several types of cores, including melt-proof conductive ceramic cores. The transportable nuclear generator coolant flow paths are configured to ensure high efficiency conversion of thermal energy into electric energy. These coolant pathways are obtained by positioning internal fins with low fluid-dynamic drag that provide core structural support while ensuring transfer of decay thermal energy from the core to the transportable nuclear generator external fins by conduction heat transfer mechanisms. In this configuration, the transportable nuclear generator core can safely and passively transfer decay thermal energy to the environment surrounding the transportable nuclear generator even in the total absence of coolant. The three modules forming the single vessel transportable nuclear generator are now described in more detail. In one configuration, the reactor power module integrates the reactor core fueled with enriched fissile material (i.e. uranium or plutonium), neutron reflectors, multiple reactivity control systems, flow channels for the coolant to efficiently circulate through the reactor power module and thermal-hydraulic systems coupling the reactor power module to the power conversion module. The reactor power module vessel may be preferentially made of C-C composite material or suitable metallic material. The core may be any suitable core with material composition and heat transfer characteristics satisfying power-rating requirements. A preferential core configuration comprises a conductive ceramic core with ceramic micro-encapsulated fuel embedded into silicon carbide (SiC) to form fuel elements. In one exemplary configuration, the transportable nuclear generator is equipped with a “melt-down proof” core comprising monolithic tri-structural isotropic fueled (MTF) elements. In this configuration, the core is made of fuel elements, manufactured with TRISO fuel in SiC pellets, hereinafter referred to as fully ceramic micro-encapsulated (FCM) fuel, sealed into the SiC or SiC-composite elements, or with tri-structural isotropic (TRISO) particles distributed in MTF elements. Any sintering, compacting or other SiC fabrication process may be used that produces SiC of adequate structural strength and resistance to irradiation in the pellet and/or the blocks. In one preferred configuration the nano-infiltration and transient eutectic phase (NITE) SiC sintering process may be used. The pellet may have a layer of unfueled SiC to surround the fueled region. The fissile fuel employed in the TRISO particles may be an oxide, carbide, oxycarbide or a nitride of uranium, plutonium, thorium or other fissile isotope. A burnable poison rare earth oxide such as Erbia or Gadolinia may be incorporated in the SiC ceramic compact. The burnable poison may also be contained in special coated particles mixed in with the fuel particles forming the pellets. The high-density non-porous SiC coating of the TRISO particles, the dense SiC matrix of the FCM fuel pellet and the SiC in the fuel element provide multiple barriers to fission product migration and dispersion, in a form that is at the same time radiation tolerant, heat conductive and compatible with high temperature operations. In another example, the transportable nuclear generator may be loaded with a thermally conductive ceramic core, wherein the conductive ceramic core is composed of the MTF elements or blocks and similarly configured reflector elements or blocks (made, for example, of carbon or SiC-composite material). In this configuration, the MTF is designed and dimensioned to avoid excessive thermal stresses during operation. One example is the quarter-circle 10-cm thick plates indicated in FIGS. 24 and 24A. Other examples are hexagonal or rectangular fuel blocks. In all configurations, fuel and reflector blocks or elements contain holes for a coolant to flow. In all configurations, pressure plates with matching coolant holes may be included at the inlet and outlet of the core to keep the core under compression at all times. The thermal conductivity of the conductive ceramic core matrix is also enhanced by the elimination of gaps between fuel compacts and blocks and the reduction of gaps between blocks, thereby reducing fuel temperature and supporting the transportable nuclear generator core passive heat transfer capability under all accident scenarios. Core reactivity may be controlled by absorbing neutrons in the reflector and preventing them from re-entering the core and by absorbing core neutrons. In the transportable nuclear generator core reactivity is controlled by operating: (1) control rods or rotary control drums in the reflector, containing neutron absorbing and reflecting materials arranged in a way to be passively engaged in absorbing mode for safety; (2) an array of in-core control rods; (3) an emergency shutdown system that injects neutron poison in the core through a passive system if the other systems fail. Control drums may feature absorbing and reflecting materials geometrically arranged so as to allow more or less neutrons to escape or be reflected back into the core depending on the rotational position. The neutron absorbing material may be a SiC-based or C-based ceramic with boron or a rare earth neutron capturing material, while the neutron reflector portions may utilize beryllium or other materials in a suitable high-temperature compatible form, with favorable neutron reflecting properties. These reactivity control features may operate independently and each may be capable of full or partial control of the core reactivity to regulate power and accomplish reactor shutdown. Other reactor core configurations may be utilized, such as fuel rods containing nuclear fissile material in the form of oxide, nitride, metal or other, with metallic or ceramic cladding and arranged in bundles as appropriate to the coolant medium. Loose fuel elements of suitable geometric shape, such as spherical pebbles may also be used. In one configuration, the transportable nuclear generator core uses an inert gas as coolant and working fluid for the power conversion module. In this configuration, the coolant could be CO2, helium, or other preferably inert gases (e.g., argon). In this example, the transportable nuclear generator core produces thermal energy while the turbo-machinery combined with various integral heat exchangers, contributes to perform a regenerative Brayton cycle, achieving high power conversion efficiency. In another configuration, the transportable nuclear generator core uses water as coolant and partially as a moderator circulating in a primary loop fully enclosed in the reactor power module. Pressure in the primary loop is regulated using an integral pressurizer. One or multiple integral separation heat exchangers provide the thermal coupling between the primary loop in the reactor power module and a secondary loop in the power conversion module. Water circulating in the secondary loop receives thermal energy from the primary loop side of the separation heat exchanger (i.e. steam generator) so as to change thermodynamic state from sub-cooled liquid to superheated steam. Water in the secondary loop does not mix with the water circulating in the primary loop. In this configuration the transportable nuclear generator core thermal energy is transferred to the turbo-machinery in the power conversion module in the form of super-heated steam. After expanding in the turbo-machinery, steam is vented to an integral condenser which passively transfers thermal energy to the internal and externally extended cooling fins of the power conversion module. As steam condenses, it is re-pressurized by a set of pumps and the secondary loop is reset by pumping sub-cooled water at the inlet of the secondary side of the separation heat exchanger. In another configuration, the transportable nuclear generator primary loop may comprise liquid metal actively circulated using recirculation pumps or passively, for thermal energy transfer to the secondary side of one or multiple separation heat exchangers. In this transportable nuclear generator core configuration, the secondary side may be coupled to a power conversion module utilizing turbo-machinery designed to satisfy the requirements of a regenerative Brayton power cycle with gas as a working fluid, or a power conversion module utilizing turbo-machinery and condenser designed to satisfy Rankine power cycle requirements, with water as working fluid. Independently of the power conversion module configurations, utilizing components designed to support Brayton or Rankine power cycle requirements, the power conversion module is directly coupled to the power generation module as rotary components forming the turbo-machinery in the power conversion module and the rotary components forming the generator-motor of the power generation module are directly mechanically coupled to the rotary shaft so as to rotate at the same velocity. The rotational speed of the shaft is determined by the thermo-hydraulics of the power conversion system, loading conditions and settings of the electronic control system regulating the electric generator-motor machine. The frequency and other electric parameters of the generator power may be controlled by integral electronic conditioning circuits. In one configuration, the power generator in the power generation module may be switched to operate as an electric motor to drive the turbo-machinery of the power conversion module during startup and after shutdown. In this configuration, startup power may be provided through a set of batteries (i.e. uninterruptable power sources), or an external source of electric power (e.g., small diesel-electric set). In most configurations, the shaft coupling all rotary components integrated in the power conversion module and power generation module may be coupled to the stationary structures of the corresponding modules using magnetic bearings. To ensure complete separation and independence of all modules, the power conversion module and power generation module modules, when coupled, utilize a flexible coupling to mechanically couple the shaft. In other configuration, a clutch may be envisioned should the rotary components of the power generation module be required to disengage from the power conversion module rotary components, or should a particular application require a differential rotary speed between the rotary components of these two modules. The following discussion emphasizes key and general transportable nuclear generator features. In all configurations (i.e. utilizing gas or liquids as coolant and/or working fluids), the transportable nuclear generator presents high component-level modularity and integration to provide a very compact transportable power-generating unit rapidly deployable and retrievable. The transportable nuclear generator features three pre-configured modules forming a single vessel when coupled. Each module can be mass-produced, easily transported independently or fully assembled and operational. The reactor power module can be hot swapped at the end of the refueling cycle or should an emergency (i.e. military operations) require rapid retrieval of the core, for example, via air lift (i.e. C17 air-transport or heavy lift helicopter transport). The transportable nuclear generator components forming the three modules rely on existing technologies (turbo-machinery from various commercial applications, and generator-motor from fast alternator-motor technologies with magnetic bearings), or mature technologies developed and tested at various national laboratory and internationally (e.g., FCM fuel). The reactor power module contains, supports, protects and cools the nuclear core, a power conversion module, comprising turbo-machinery (turbines and compressor equipment for a gas cooled transportable nuclear generator configuration), integral heat exchangers (i.e. recuperator, pre-cooler and inter-cooler) as suited to the selected coolant and thermodynamic power cycle (i.e. regenerative, or partial Brayton or Rankine), and the power generator module, containing a starter/generator unit. The fully assembled transportable nuclear generator may be configured to operate horizontally with minimum site preparation or vertically for underground installations. In all configurations, the transportable nuclear generator allows rapid fielding and startup, as well as fast retrieval of the full reactor or the individual modules. Refueling may be executed by swapping the “used” reactor power module, containing the spent core, with a new module containing a fresh core. Should malfunctions develop in the power conversion module or power generation module their replacement will be executed by simply swapping the malfunctioning module with a new or factory-refurbished one. Depending on the selected working fluid, the transportable nuclear generator does not require the complex network of piping and equipment normally forming the balance of plant of all small modular reactor designs. The transportable nuclear generator is fully integrated and ready to produce power immediately after deployment. If the transportable nuclear generator is configured for horizontal operations, the resulting power generator allows easy deployment at sites characterized by seismic activities, on-board ships and several other applications requiring critical power. The reactor power module, power conversion module, and power generation module may be designed to be individually and independently secured onto standardized transport, operational, and storage platforms, with a variety of transportation options in compliance with civilian and military transportation standards. The transportable nuclear generator does not require large bodies of water for its passive cooling, and may utilize local water or dry, non-evaporative, or simply environmental air as its ultimate heat sink. In off-normal situations, the transportable nuclear generator will be capable of relying solely on passive decay thermal energy removal from the core through conduction heat transfer (in the total absence of core coolant) to the walls of the finned modules, and passive convective heat transfer to the ambient air surrounding the transportable nuclear generator. The reactor power module, when separated from the rest of the transportable nuclear generator for refueling, is capable of passive decay heat removal solely based on radiative and ambient air convective mechanisms. When the transportable nuclear generator is configured to operate with a power conversion module based on Brayton cycle conversion, it provides the option of utilizing high temperature reject heat that can be used to support various process heat applications. In this configuration, the transportable nuclear generator may be equipped with heat exchangers for the production of low- and/or high-grade process heat to be distributed to equipment dedicated to desalination, bio-fuel processing, district heating, or other industrial uses. The power generation module may be configured to start the turbo-machinery while heating and pressurizing the transportable nuclear generator primary loop with the support of uninterruptable power sources represented by integral battery pack (i.e. comprised with the power generation module), or a small external diesel-electric generator. A fully assembled transportable nuclear generator unit represents a power plant capable of startup, shutdown, normal operation, while passively maintaining safe fuel temperature margins during transients and emergency conditions. Other devices, apparatus, systems, methods, features and advantages of the invention will be or will become apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the invention, and be protected by the accompanying claims. The transportable nuclear generator exemplary configurations disclosed herein are described in the context of providing a safe, rapidly transportable and operational nuclear generator system for various applications requiring electric energy and process heat. Those of ordinary skill in the art will understand that the transportable nuclear generator integral modules may be configured for any power demanding application having a need for reliable and continuous electric power, possibly at location with no other alternative of employing diesel-electric generators with high operating cost and pollutant emissions. The transportable nuclear generator may be configured with different fin shapes to enhance passive heat transfer mechanisms from the transportable nuclear generator internals to the environment (ultimate heat sink). FIG. 1 is a top perspective cross-sectional view of an example transportable nuclear generator 100 block diagram, indicating the boundaries of the reactor power module 200, the power conversion model 300, and the power generation module 400 of an exemplary implementation. FIG. 2 is a top perspective cross-sectional view of an example transportable nuclear generator block diagram showing the single vessel transportable nuclear generator 100 formed by coupling the three modules (reactor power module, power conversion module, and power generation module) and comprising all the integral equipment for horizontal or vertical operation. FIG. 3 is a side view of the example implementation shown in FIG. 1 illustrating each module comprising external fins 208 on the reactor power module, 208 and 208A on the power conversion module, and 208 on the power generation module. Fins 208 and 208A are developed in a manner to provide enhanced heat transfer area for passive cooling, structural hardening and shielding features of the transportable nuclear generator 100. Referring to FIGS. 1 and 2, the transportable nuclear generator 100 is formed by three main modules: The swappable reactor power module 200, housing the core 203, control and core shutdown systems 204, core control and reflector system 205, coolant flow reversing structures 206 (shown in detail in FIG. 7), and passive core heat transfer structures 207. The reactor power module is coupled to the power conversion module 300, by a sealing and supporting flange 201. The power conversion module 300, is sealed to the reactor power module using sealing flange 301, and comprises turbo-machinery equipment 304, low backpressure heat exchangers “recuperator” 305, “pre-cooler” 306, and “intercooler” 307, flow reversing structures 309 (similar to 206) and a shaft 310 mechanically coupled to all rotary components of the power conversion module 300 and the power generator module 400. The power conversion module 300 is sealed and coupled to the power generation module 400 using flange 301. The power generation module 400 is sealed to the power conversion module 300 using sealing flange 401 and comprises a fast generator-motor 402 with embedded electronic controllers, Uninterruptable Power Sources 403 (i.e. batteries) to be utilized during start-up operations, generator integral cooling system/heat exchanger 404, sealing magnetic bearings 405 with interfacing and flexible coupling structures to mechanically couple with rotary shaft of turbo-machinery 304. Once thermal-hydraulically coupled through sealing flanges 201-301, 301-401, the three modules form a single hardened vessel 100 passively exchanging thermal energy with the surrounding environment using fins 208 and 208A. In addition to providing heat transfer features to ensure thermal energy transfer from the modules internals to the transportable nuclear generator 100 external environment, fins 208 and extended fins 208A have also structural hardening and shielding features. The pressure boundary formed by partition 209 in the reactor power module 200 allows for different coolants and separation of the environments represented by the primary pressure boundary 311 with a second pressure boundary represented by chamber 210 housing control systems 204 and 205. Similarly, partition 406 in the power generation module 400 allows sealing and separation of the generator-motor environment 407 from the environment 311 represented internally power conversion module 300. The rotary equipment forming the turbo-machinery systems 304 of the power conversion module 300, are mechanically coupled to a single shaft 310 also mechanically coupled to the shaft of the rotary components integrated in the generator-motor 402 of the power generation module 400, thus all of the rotary equipment is matched to rotate at the same speed using frictionless magnetic bearings 405 (only shown at one side of turbo-machinery system 301 and generator motor 402). Each module may be transported independently, or all three fully assembled and forming a fully operational transportable nuclear generator vessel 100. All modules are interfaced through pressure and cabling fittings ports 211. These ports allow for coolant charging or discharging operations, monitoring and control of various electrical functions (i.e. control rod drive or rotary control and reflector mechanisms). Additionally, fitting ports 211 allows for electric bus connections from the generator-motor 402 to the electric grid at the site of deployment. Fully assembled or in separate modules transport of the transportable nuclear generator 100 may be executed in compliance with transportation standards (i.e. utilizing standard transportation equipment). When transported fully assembled, the transportable nuclear generator 100 represents a rapidly deployable and retrievable fully operational electric power generator. In one configuration, the materials forming the pressure vessels representing each module may utilize composite structures of Carbon and Silicon carbide as reflector and also as pressure boundary (pressure vessel). The use of a light weight low-neutron absorption vessel will allow the option of using external mechanisms of neutron reflection to improve the neutron economy of small size core 203 (FIG. 1). In one exemplary configuration shown in FIG. 1, the transportable nuclear generator modules may be coupled using sealing and locking flanges 201-301 and 301-401 so as to form a single hardened pressure transportable nuclear generator vessel 100 operating horizontally. In another configuration, shown for example in FIG. 2, by re-orienting external transportable nuclear generator 100 heat transfer fins 208B, 208C and 208D, the transportable nuclear generator may be configured to operate vertically. All modules comprise highly integrated heat exchangers formed by internal fins 212, 207, 305, 306, 307 and 404, for example, shown in FIGS. 1 and 2. These integral heat exchangers are thermally coupled to external fins 208 and 208A in FIG. 1, and to fins 208B, 208C, and 208D (FIG. 2), when re-oriented for transportable nuclear generator 100 vertical operation or operation within underground installations. All internal fins in each module may be configured to provide support to internal components while substantially reinforcing the overall transportable nuclear generator structure as they form multiple structural ribs, thus hardening the whole transportable nuclear generator vessel 100, and as coolant flow channels. In one configuration, the transportable nuclear generator 100 reactor control mechanisms may comprise control drive mechanisms 205 shown, for example, in FIG. 4, configured to control neutron absorbing materials 215 by inserting/withdrawing said materials 215 within regions of neutron reflectors 214, in addition to control drive mechanisms 204 configured to insert/withdraw neutron absorbing materials 216 into regions of core 203, and in addition to a central control rod drive mechanism 219 configured to insert neutron absorbing material within regions substantially central to core 203. In another configuration, the transportable nuclear generator 100 reactor control mechanisms may comprise control drive mechanisms 221 (FIG. 6), configured to control neutron absorbing materials 215 by inserting/withdrawing said materials 215 within regions of neutron reflectors 214, in addition to control drive mechanisms 204 configured to insert/withdraw neutron absorbing materials 216 into regions of core 203, in addition to a central control drive mechanism 219, configured to insert/withdraw neutron absorbing materials 220 into/out of a substantially central location of core 203. In another configuration, shown in FIG. 7, the transportable nuclear generator 100 reactor may be configured to utilize a reactor power module 200 comprising reactor control mechanisms including rotary drums 213 containing neutron absorbing materials on one side and neutron scattering materials (reflector) on the opposite side of each rotary drum. The rotary drums 213 comprise a magnetic coupling that passively always orientates the drums by rotating them in a manner that the neutron absorbing materials face core 203, thus forcing a sub-critical condition of core 203. When the rotary control drums 213 are rotated using electromagnetic control (i.e. solenoid, electromagnetic, motor-assisted or pneumatic actuation, not shown in this FIG. 7), the rotary drum exposes the neutron reflective site to core 203, thereby increasing its criticality. In case of loss of electric power, the rotary control drum always passively orientate themselves in a manner that the neutron absorbing side faces core 203, thereby forcing shutdown conditions. This configuration remains effective even if transportable nuclear generator vessel 100 is dislodged from its supporting platform and rotated, for example, as a result of explosions induced by hostile events. As shown in FIGS. 5, 6, 8, 9 and 21, the inlet and outlet sections of core 203, with respect to coolant flow direction, are faced by neutron reflectors 217, and 218 respectively. Additionally, the reactor power module comprises an emergency shutdown system that injects neutron poison in the core through a passive system if all other control systems fail. To summarize aspects addressing reactor control, reactivity control for core 203 may be performed in one configuration by control rods 215 in the reflector 214, containing absorbing and reflecting material arranged in a way to be passively engaged in absorbing mode for safety, and by driving multiple in-core control rods 216. In a further configuration reactivity control for core 203 may be performed by driving in-core control rods 216, a central control rod 220 and rotary control drums 213, or a combination of these configurations in addition to emergency neutron poison injection to provide an additional independent core 203 shutdown mechanism. Control rod material is likely to be a SiC-based or C-based ceramic with boron or a rare earth absorbing material, and beryllium as reflector material. With reference to FIG. 1, the integral heat exchanger 212, within the reactor power module 200, may be configured to provide passive cooling to control rod drive mechanisms 204 and 205. With reference to FIGS. 1, 2 and 5, integral heat exchangers 207 may be configured to passively remove decay heat from core 203 via conduction heat transfer between the inner core 203, and the reactor power module 200 external fins 208 (FIG. 1 and 3), or 208B (FIG. 2). Integral heat exchanger 207 may be configured to transfer decay thermal energy from core 203 even under total loss of coolant scenarios. In some configurations, core 203 may be formed by fuel elements thermally coupled to materials that form highly thermally conductive pathways 207 as shown, for example, in FIG. 7. With reference to FIGS. 4 and 5, the power conversion module 300 comprises a series of integral heat exchangers. These may be configured to function as recuperator 305, pre-cooler 306, and inter-cooler 307, in agreement with Brayton power cycle thermodynamic configuration. Additional, integral heat exchangers fully integrated into dedicated modules are represented by the generator-motor integral heat exchanger 404, integrated into the power generation module 400. In one preferential configuration of the transportable nuclear generator integrated in the single vessel 100 of FIGS. 1, 2, 3, 4 and 5, the power conversion module 300 houses the turbo-machinery system 304 and integral heat exchanger hardware to convert the heat generated in the reactor power module 200 into mechanical power coupled into the rotating shaft 310. In order to couple rotary turbo-machinery on the same shaft 310, and in the enclosure represented by the power conversion module 300, and assuming gas 312 (FIG. 5) as a working fluid with proper thermo-physical characteristics, high temperature gas 312 produced by flowing through core 203 in the reactor power module, inlets gas turbines 304A. With reference to FIGS. 5 and 6, after expansion in the various stages of turbines 304A, the gas enters the integral heat exchangers defined as recuperator 305, and pre-cooler 306 prior to entering low pressure side of compressor 304B and high pressure side of compressor 304C with the gas flowing through an integral intercooler heat exchanger 307, before reversing flow direction using a low-drag flow reversing structure 206 (FIG. 1), flow on the hot side of the recuperator 305, and finally resetting the Brayton gas cycle by inletting the cold side of core 203 in the reactor power module 200. The pre-cooler 306 and the inter-cooler 305 may be configured as gas to air or gas-to-liquid heat exchangers that transfer the residual waste heat to the ultimate heat sink passively via fins 208 and extended fins 208A (FIG. 3). In this configuration, the reactor cooling gas 312 and Brayton working gas 312 may be the same. Gas 312 may be CO2, Helium, Argon or another fluid with thermal-physical properties that satisfy thermodynamic and core requirements. Under the regenerative Brayton cycle configuration, the transportable nuclear generator power conversion efficiency may be approximately 45%. Bypass valve 313 allows execution of load following according to electric demand by essentially short-circuiting gas 312 exiting the core. As shaft 310 is mechanically coupled to the power generation module 400 and the turbo-compressor in the power conversion module 300, the generator-motor 402 may be configured for start-up operations so as to use batteries integrated in uninterruptable power supply units 403 to convert the generator into a motor and use motor 402 as a drive for the turbo-machinery to act as a gas circulator system at startup and shutdown. In one configuration, shaft 310 may be coupled to stationary elements of the power conversion module and power generation module using magnetic bearings 405 with catcher bearings engaging in case of sudden loss of electric power within the transportable nuclear generator control systems, electronic controllers or electro-magnetic bearing coils malfunction. To allow for the power conversion module to be separated (i.e. during individual module transport) from the power generation module, shaft 310 may be formed by two separate shafts coupled by a flexible high-speed coupler at the location of module coupling flanges 301-401. The integral turbo-machinery and generator-motor equipment, allow for operation without need for external balance of plant, thereby substantially decreasing overall footprint, vulnerabilities, and the probability for loss of coolant scenarios. With reference to FIGS. 7, 8 and 9, the reactor power module 200 may employ several types of cores 203, including melt-proof conductive ceramic cores. In one exemplary configuration shown in FIG. 7, core 203 is formed by fuel elements 221 with various geometries. Fuel elements 221 may be configured to comprise coolant flow paths 222 so as to ensure high efficiency conversion of thermal energy transferred to the coolant while circulating within the flow path. Coolant flow pathways 222 are configured to allow a fluid to flow through fuel elements 221 and/or to allow control mechanisms to be inserted or withdrawn from core 203. In one configuration of core 203, to enhance conduction heat transfer mechanisms, cooling pathways 207 may be obtained by thermally coupling fuel elements 221 with fins that form the conductive cooling pathways 207 as they provide a heat transfer conduit from core 203 inner locations all the way to external fins 208 through internal fins 207A. Fins 207A may be configured to direct gas flow exiting the recuperator 305 into the flow reversing structures 206, while providing structural support for core 203 internals and heat transfer pathways to passively transfer thermal energy (i.e. decay heat) from the core to fins 208. Flow reversing structures 206 may be configured so as to offer low fluid-dynamic drag, and provide core structural support while ensuring transfer of decay thermal energy from the core to the transportable nuclear generator external fins 208 by conduction heat transfer mechanisms. Therefore, core 203 can safely and passively transfer decay thermal energy to the environment surrounding the transportable nuclear generator even in the total absence of coolant. FIGS. 10, 10A and 10B are perspective views of an example implementation of a low backpressure recuperator integral heat exchanger integrated into the power conversion module 300. As shown in these FIGS. 10, 10A and 10B, the working fluid, gas 312, inlets the recuperator 305 on one side, executes a full 360°, loop and exits the recuperator (symmetrical in one exemplary configuration). In this manner gas 312 exchanges thermal energy with the inner surfaces of recuperator 305 without mixing with the fluids in thermal contact with the outer surfaces of recuperator 305. FIG. 11 is a perspective view of a fully assembled exemplary configuration of the low backpressure integral recuperator 305 heat exchanger integrated in the power conversion module 300. This configuration provides separation between the working fluid 312A (hot gas) exiting the turbo-machinery, and the fluid 312B (cold gas) returning from the compressor 304C described in FIGS. 5 and 6. FIG. 12 is a perspective view of an example implementation of the fully assembled low back-pressure integral recuperator 305 heat exchanger in FIG. 11 illustrating the heat transfer induced by separate flow patterns between the fluid 312A inletting the inlets of the heat exchanger 305, shown in FIG. 10, and the fluid 312 B returning from the intercooler sections 307 of the power conversion module, thereby executing the function of recuperating thermal energy otherwise wasted at the discharge of the turbo-machinery with minimum backpressure due to the unique geometry of heat exchanger 305. FIG. 13 is a perspective view of an example implementation of a device configured to swap “hot” reactor power module and specialized to execute sealing of the reactor power module in preparation for transport or storage. As shown in this FIG., an example implementation of a module swapping device 500 utilizes a flange 505 to be coupled with flange 503 to execute sealing of the reactor power module 200 and de-coupling of power conversion module 300. As flanges 503 and 505 are coupled they seal against the flanges 201 and 301 shown in FIG. 1. Hydraulically activated fasteners 501 de-couple flanges 201 and 301 while mechanism 502 inserts a closing section 501 which seals reactor power module 200. FIGS. 14 and 15 are perspective view illustrating an exemplary sequence utilized by swapping device 500 to de-couple the reactor power module 200 from the fully assembled transportable nuclear generator single vessel 100 and seal reactor power module 200 with a sealing flange 501. FIG. 16 is a perspective view illustrating an exemplary modular transport platform 600 compliant with transportation standards and equipped with guides 601 to allow securing the modules 200, 300 and 400 during transport and operation. In this configuration, the modules can slide for rapid coupling or decoupling without needing heavy lifting cranes at the site of deployment. FIG. 17 is a perspective view illustrating an exemplary transportable nuclear generator transport platform 600 shown in FIG. 16, with added shielding 700 and passive cooling structures 701 to allow rapid reactor power module 200 “hot” retrieval (core retrieval short time after shutdown). In this embodiment, the entire transportable nuclear generator single vessel 100, or only the reactor power module 200 may be flooded so as to increase heat transfer should the reactor power module 200 be transported a relatively short time after shutdown. In this configuration, the core continues to passively cool down while inflatable shields 700 may be filled with water so as to form a thick water wall to attenuate a radiation field during rapid core retrieval. FIG. 18 is a side cross-sectional view of a modified version of the exemplary transportable nuclear generator block diagram showed in FIG. 1, wherein the single vessel comprising all the equipment for horizontal (or vertical) operation of the transportable nuclear generator is configured for operation with water 804 as core 203 coolant circulating in a primary loop as for typical Pressurized Water Reactor (PWR). The working fluid 805 in the secondary loop forming a Rankine power cycle is also water. In this configuration the transportable nuclear generator comprises a primary and secondary loops separated by a separation heat exchanger whose primary side 802 receives thermal energy from core 203 through water 804 circulating by forced convection via reactor coolant pumps 801. With reference to FIGS. 18, 19, 20, and 21, in an exemplary configuration of the transportable nuclear generator operating with water as coolant and working fluid the reactor coolant pumps 801 may be configured as canned pumps positioned either on the dry head or chamber 210, as shown in FIG. 18, or on the annular jacket shown in FIG. 21. Pressure in the primary loop is regulated using a pressurizer 800 comprising heaters 800B and sprayer 800A (FIG. 21). Control and passive decay heat removal systems in this configuration are similar to those described in FIGS. 1-7. The secondary loop represented by flow path 805 receives thermal energy from the primary loop using the separation heat exchanger 802 and 803. Water is circulated through the secondary side of heat exchanger 803 using feed-water pumps 808. As steam outlets the secondary side of separation heat exchanger 803, it expands in the turbo-machinery 806 wherein steam energy is converted into mechanical energy transferred to the power generation module 400 and the generator 402. Turbo-machinery 806 and fast generator 402 are mechanically coupled using shaft 310 and separation mechanisms between the power conversion module 300 and power generation module 400 as those described in FIGS. 1-7. As steam is vented at the discharge of turbo-machinery 806 it inlets an integral heat exchanger re-heater 809 (FIGS. 19 and 20) prior to condensing in the condenser 807, thus re-setting the Rankine power cycle. Condenser 807 transfers thermal energy to the environment using fins 208 with gravity driven heat transfer mechanisms as those described in FIGS. 1-7. Short-term decay heat removal from core 203 may be executed in the absence of electric power by utilization of the UPS 403. For configurations wherein core 203 may be formed by melt proof ceramic materials, passive cooling by conduction mechanisms, even in the total loss of coolant scenario, ensure core temperatures below safety margins. The transportable nuclear generator configuration comprising a primary and a secondary loop operating at different pressure boundaries may also utilize a liquid metal-cooled reactor power module separated from the power conversion module by the separation heat exchanger and allowing utilization of a Brayton or Rankine power cycle in the secondary loop. FIG. 22 is a perspective representation to provide a scale indication of an exemplary fully assembled transportable nuclear generator secured on a standard transport platform 900 for rapid deployment and ready to generate power at any deployment site, including sites with arid and extreme environmental conditions. FIGS. 23 and 23A are perspective representations of an exemplary reactor power module of the transportable nuclear generator, secured on a standard transport platform 900 for rapid “hot” reactor power module transport (i.e. emergency site extraction), are shown with add-on passive cooling features 701 and inflatable shields 700 to ensure radioactive shielding under hot core removal scenarios. FIGS. 24 and 24A are perspective views of preferential conductive ceramic core sections 221 and Fully Ceramic Micro-encapsulated (FCM) fuel elements 901 forming a melt-proof core that can be passively cooled even in total absence of coolant. FCM fuel utilizes low-neutron absorption ceramic composite materials as, for example, Silicon-Carbide (SiC). SiC composites have many advantages with respect to graphite for use in reactors as they have very low reaction kinetics with water and air at high temperature, do not produce carbon dust, have no Wigner effect from fast energy release at low temperature after irradiation, have good tolerance to radiation, it manifests very small dimensional change under irradiation, and offers non-porous impermeable barrier to fission product dispersion even at very high temperature. In one configuration, core 203 may be formed by fuel elements 901 and 221 made of a composite structure of unidirectional fiber-reinforced NITE-sintered SiC with SIC fibers to insure toughness. Core 203 restraints and hot ducts and all flow paths 220A and control rod channels 222 are also made of fiber-reinforced composites. For example, the integral recuperator heat exchanger 305 shown in FIG. 6 may be formed with SiC PC (printed circuit) gas-gas heat exchanger, designed to fit in the annular space available around the turbomachinery so as to offer compactness, effectiveness and low back-pressure. Other SiC structures in core 203 include control rods, made of a sintered mix of SIC-Gd203 and Er203 and control rod sleeves. Finally the pressure vessel may be made of pre-stressed SiC composite. In some configurations, fuel elements 221 may provide partial cuts 906 and 905 to allow for controlled fractioning of fuel elements 221 without cracks propagating through compacts 902 or fuel elements 901 should these be subjected to severe kinetic stresses as those caused by explosion, for example, induced by hostile events (missile hit). In this manner, and as a result of catastrophic attack, fuel blocks or elements 221 may be fractured along controlled partial cuts 906 or 905, thereby leaving fuel elements 901 intact even under the most severe beyond design basis accident or attack scenario. This feature allows the core or its fractured fuel blocks 221 to contain all volatiles and significantly mitigate the consequences of a severe core breach scenario. As all radioactive volatiles remain trapped within fuel elements 901 under severe design basis and beyond design basis accident or attack scenarios, the transportable nuclear generator does not require evacuation planning zones as required by all SMR and large reactors. Those of ordinary skilled in the art will understand how combinations of the features described may be formed to arrive at example implementations that may not be specifically shown in the figures. It will be understood that various aspects or details of the invention may be changed without departing from the scope of the invention. Furthermore, the foregoing description is for the purpose of illustration only, and not for the purpose of limitation—the invention being defined by the claims.
	summary
	abstract	Techniques for forming a target and for producing extreme ultraviolet light include releasing an initial target material toward a target location, the target material including a material that emits extreme ultraviolet (EUV) light when converted to plasma; directing a first amplified light beam toward the initial target material, the first amplified light beam having an energy sufficient to form a collection of pieces of target material from the initial target material, each of the pieces being smaller than the initial target material and being spatially distributed throughout a hemisphere shaped volume; and directing a second amplified light beam toward the collection of pieces to convert the pieces of target material to plasma that emits EUV light.
	description	The present invention relates to a debris filter for a nuclear reactor installation, of the type comprising a plurality of plates arranged side-by-side in a spaced relationship and delimiting between them flow passages extending through the debris filter from a lower inlet face to an upper outlet face of the debris filter, each passage having an intermediate section offset with respect to an inlet section and an outlet section. A nuclear fuel assembly for light water reactor conventionally comprises a bundle of elongated fuel rods extending parallel to each other. In use, the fuel assembly is oriented vertically in a nuclear reactor core and a coolant fluid is caused to flow upwardly between the fuel rods. Debris might be present in the coolant fluid and damage the fuel rods thus requiring removing or replacing the fuel assembly or damaged fuel rods. In a known manner, a debris trap or filter is placed upstream the bundle of fuel rods to trap debris. EP 0 455 010 discloses a debris filter having a plurality of plates having a wave shape delimiting between them flow passages. The curvature of the passages allows trapping debris whilst limiting flow resistance of the debris filter. Nevertheless, thin and short debris oriented perpendicular to the flow direction may pass through the filter and flexible longer elongated debris may also pass through the filter. An object of the invention is to provide a debris filter allowing improved debris trapping, namely thin debris for instance in the form of short or flexible wires. To this end, a debris filter of the above-mentioned type is provided, wherein at least one plate is formed with debris catching features distributed along the plate and protruding into at least one passage delimited by the plate. In other embodiments, the debris filter comprises one or several of the following features, taken in isolation or in any technically feasible combination: the debris catching features define debris catching spaces tapering upwardly; each pair of adjacent debris catching features of the plate define a debris catching space tapering upwardly; the plate is formed with debris catching features provided as vanes, each vane being cut in the plate and bent or twisted; the vanes are cut in a lower edge of the plate; the plate is formed with adjacent vanes twisted in the same direction; the plate is formed with vanes bent in one direction or twisted in one direction alternating with vanes bent in the opposite direction, respectively twisted in the opposite direction; the plate is formed with debris catching features provided as teeth cut in the plate, each tooth protruding obliquely inside a passage delimited by the plate and downwardly; the debris filter comprises teeth protruding one face of the plate alternating with teeth protruding the opposite face of the plate; the debris filter as described above, comprises connection strips intersecting the plates for maintaining the spacing between the plates; each plate comprises connection slots extending from the upper edge of the plate, each slot receiving a connection strip intersecting the plate; each connection strip is formed with spacing means for maintaining spacing between the upper portions of said plates; each connection strip is formed with spacing tabs cut in the upper edge of the connection strip, each spacing tab being twisted; and the lower edge of each connection strip is formed with interlocking slits, each for engaging the lower closed end of a slot of the plate in which the connection strip is received. A nuclear fuel assembly comprising a bundle of fuel rods and a debris filter as defined above is also provided. A nuclear fuel assembly as those illustrated in FIGS. 1 and 2 extends along a longitudinal axis L. Axis L extends vertically when the fuel assembly is disposed inside a nuclear reactor. In the following, the terms “upper” and “lower” refer to the position of the fuel assembly in a nuclear reactor. The nuclear fuel assembly 2 illustrated in FIG. 1 is adapted for a Pressurized Water Reactor (PWR). It comprises a bundle of nuclear fuel rods 4 and a structure 6 for supporting the fuel rods 4. Each fuel rod 4 comprises a tubular cladding, pellets of nuclear fuel stacked in the cladding, and caps closing the upper and lower ends of the cladding. The structure 6 comprises a lower nozzle 8, an upper nozzle 10, a plurality of guide-tubes 12 and supporting grids 14 distributed along the guide-tubes 12. The lower nozzle 8 and the upper nozzle 10 are spaced one from the other along the longitudinal axis L. The guide-tubes 12 extend longitudinally between the lower nozzle 8 and the upper nozzle 10 and connect the nozzles 8, 10. The guide-tubes 12 maintain a predetermined longitudinal spacing between the nozzles 8, 10. Each guide-tube 12 opens upwardly for allowing insertion of a control rod downwardly inside the guide-tube 12. The grids 14 are distributed along the guide-tubes 12 and connected to them. The fuel rods 4 extend longitudinally between the nozzles 8, 10 through the grids 14. The grids 14 support the fuel rods 4 transversely and longitudinally. The lower nozzle 8 comprises a lower tie plate 16, a skirt 19 extending downwardly from the lower tie plate 16, a debris filter 20 placed below the lower tie plate 16 and inside the skirt 19 for filtering coolant entering the fuel assembly 2, and feet 18 extending the skirt 19 downwardly for positioning the fuel assembly on the lower plate of the nuclear reactor core. The nozzles 8, 10 are arranged for allowing a vertical coolant flow through the fuel assembly 2 from lower end toward upper end thereof as indicated by arrow F in FIG. 1. The nuclear fuel assembly 2 illustrated in FIG. 2, where same numeral reference as in FIG. 1 designate similar elements, is for a boiling water reactor (BWR). It comprises a bundle of nuclear fuel rods 4 and a tubular water channel 13 encased in a tubular fuel channel 15. The fuel rods 4, the water channel 13 and the fuel channel 15 extend longitudinally parallel to axis L. Each fuel rod 4 comprises a tubular cladding, pellets of nuclear fuel stacked in the cladding, and caps closing the upper and lower ends of the cladding. The fuel rods 4 are arranged in a lattice and the water channel 13 replaces at least one of the fuel rods 4 in the lattice. The fuel channel 15 is partially cutaway to show the inside of the fuel assembly 2 and some fuel rods are cut away to show the water channel 13. The BWR fuel assembly 2 comprises a lower nozzle 8, an upper nozzle 10 and supporting grids 14 distributed along the water channel 13 and connected to it. Only two spacer grids 14 are visible on FIG. 2. The function of the spacer grids 14 is to maintain the fuel rods axially and transversely with a transverse spacing between the fuel rods 4. The fuel rods 4, the water channel 13 and the fuel channel 15 extend from the lower nozzle to the upper nozzle, with the water channel 13 and the fuel channel 15 connecting the lower nozzle 8 and the upper nozzle 10. The lower nozzle 8 comprises a lower tie plate 16, a skirt 19 extending downwardly from the lower tie plate 16, a debris filter 20 placed below the lower tie plate 16 and inside the skirt 19 for filtering coolant entering the fuel assembly 2, and a tubular transition piece 21 extending the skirt 19 downwardly for connection to a coolant feeding duct. The nozzles 8, 10 are arranged for allowing a vertical coolant flow through the fuel assembly 2 from lower end toward upper end thereof as indicated by arrow F in FIG. 2. A debris filter 20 suitable for a PWR fuel assembly and a BWR fuel assembly will be described in greater details with reference to FIGS. 3-8. As illustrated on FIG. 3, the debris filter 20 is in the shape of a screen and has a lower inlet face 22 and an upper outlet face 24. The debris filter 20 comprises a plurality of plates 26 arranged side-by-side in a spaced relationship defining between them flow passages 28 extending through the debris filter 20 from inlet face 22 to outlet face 24. The plates 26 are distributed in a first transverse direction T1 perpendicular to the fuel assembly axis L. The plates 26 are elongated and extend parallel to each other in a second transverse direction T2 (FIG. 4) perpendicular to the first transverse direction T1 and to the fuel assembly axis L. Each pair of adjacent plates 26 defines a passage 28. Each plate 26 extends between the inlet face 22 and the outlet face 24. Each plate 26 has a lower portion 30 extending from the inlet face 22, an upper portion 32 extending from the outlet face 24 and an intermediate portion 34 extending between the lower portion 30 and the upper portion 32. Each plate 26 has opposed plate faces 36. Each passage 28 allows coolant to flow through the debris filter 20. Each passage 28 is provided such that there is not straight flow path through the passage 28 in the flow direction F through the debris filter 20. The outlet of each passage 28 can not be seen in straight line from the inlet of said passage 28. Each passage 28 comprises an inlet section 40 extending from the inlet face 22, an outlet section 42 extending from the outlet face 24 and an intermediate section 44 offset laterally with respect to the inlet section 40 and the outlet section 42. Each plate 26 is curved. The intermediate portion 34 is waved from lower portion 30 to upper portion 32. Lower portion 30 and upper portion 32 are substantially coplanar and the intermediate portion 34 protrudes laterally. The intermediate portion 34 delimits an intermediate section 44 with the intermediate portion 34 of each adjacent plate 26. As illustrated on FIG. 1, the debris filter 20 comprises two sets of plates 26 disposed in reversed direction to provide symmetry with respect to a median plan of the debris filter 20. As illustrated on FIG. 2, the debris filter 20 comprises one set of plates 26 disposed in same direction to avoid bigger intermediate section 44 in the median plan of the debris filter 20. Back to FIG. 3, the lower portion 30 of each plate 26 is formed with debris catching features distributed along the plate 26 and protruding into at least one passage 28 delimited by the plate 26. The debris catching features protrude in the inlet section 40 of each passage 28. As illustrated on FIG. 4, the lower portion 30 of each plate 26 is formed with a plurality of debris catching vanes 46 distributed along the plate 26. The vanes 46 are formed by cutting notches 48 in a lower edge of the plate 26 and twisting the portion of the plate 26 defined between two adjacent notches 48. Each vane 46 is twisted by rotating the lower free end of the vane 46 with respect to the upper fixed end of the vane 46 connected to the rest of the plate 26 about a median longitudinal axis of the vane 46 extending between said lower free end and upper fixed end. Each plate 26 comprises vanes 46 twisted in one direction alternating with vanes 46 twisted in the other direction. As illustrated on FIG. 5, as a result of the twisting, each vane 46 protrudes from each plate face 36. Each vane 46 comprises one side portion protruding obliquely from a face 36 of the corresponding plate 26 into the passage 28 delimited by said face and downwardly, and a second side portion protruding obliquely from the other face 36 of the plate 26 into the passage 28 delimited by said other face and downwardly. Each notch 48 separating a pair of adjacent vanes 46 exhibits a V-shape converging upwardly, that is in coolant flow direction F. The adjacent side edges of each pair of adjacent vanes 46 protrude the same plate face 36 such that the inlet of the notch 48 delimited between said adjacent edges extends obliquely into a passage 28 and downwardly. Each notch 48 has a wide lower end offset inside a passage 28 delimited by said plate face 36. Each notch 48 defines an upwardly tapering debris catching space. As illustrated on FIGS. 3 and 4, the debris filter 20 comprises a plurality of connection strips 50 intersecting the plates 26 and maintaining the plates 26 in spaced relationship in the first transverse direction T1. The strips 50 are elongated and extend parallel to each other perpendicularly to the plates 26 and to the assembly axis L. The strips 50 extend in the first transverse direction T12 and are distributed in spaced relationship in the second transverse direction T21. The strips 50 divide each passage 28 into a plurality of channels 51 (FIG. 4) in the second transverse direction T2. Each strip 50 is located in register with a vane 46. Each channel 51 extends in register with a notch 48. As illustrated on FIG. 7, each plate 26 comprises connection slots 52 distributed along the plate 26. Each slot 52 extends downwardly from the upper edge of the plate 26 through the upper portion 32 and the intermediate portion 34. Each slot 52 is for receiving a respective strip 50 intersecting the plate 26. Each slot 52 is located along the plate 26 in register with a vane 46. As illustrated on FIG. 6, each strip 50 is provided with interlocking slits 54 cut in a lower edge of the strip 50. Each interlocking slit 54 is arranged for interlocking with the lower closed end of a slot 52 of a plate 26 intersected by the strip 50 for locking the lower edge of the strip 50 with the plate 26 and maintaining the spacing between the lower portions 30 of the plates 26. Each strip 50 is formed with a plurality of spacing tabs 56 cut in the upper edge of the strip 50 and distributed along said upper edge. Each spacing tab 56 is for maintaining the spacing between a pair of adjacent plates 26 intersected by the strip 50. Spacing tabs 56 are formed in each strip 50 by cutting slits in the strip upper edge and twisting the portion of the strip 50 defined between two adjacent slits. As illustrated on FIG. 8, as a result of the twisting, each spacing tab 56 of a strip 50 extending between two adjacent plates 26 intersected by the strip 50 is offset with respect to the slots 52 of the two adjacent plates 26 receiving the strip 50. Each spacing tab 56 thus prevents facing faces 36 of the two adjacent plates 26 from getting closer by abutting on the sides of the slots 52. Each spacing tab 56 allows maintaining the spacing between the upper portions 32 of two adjacent plates 26 in a simple and reliable manner. This allows fixing the connection strips 50 to the plates 26 for instance by brazing at the upper edges thereof in a geometrically controlled manner. In alternative or in addition, each strip 50 is formed with a plurality of guiding dimples 58 stamped close to upper edge of the strip 50 and distributed along said upper edge. Each dimple 58 is for maintaining the spacing between a pair of adjacent plates 26 intersected by the strip 50. Each dimple 58 thus prevents facing faces 36 of the two adjacent plates 26 from getting closer by abutting on the dimples 58. Each dimple 58 allows maintaining the spacing between the upper portions 32 of two adjacent plates 26 in an even simpler and more reliable manner. In the embodiment of FIGS. 6-8, each strip 50 comprises dimples 58 protruding one face alternating with dimples 58 protruding the other face along the strip 50. In an alternative embodiment, dimples 58 protrude for instance one of the two faces of the strip 50. In operation, coolant flows through the debris filter 20 from the inlet face 22 to the outlet face 24. Coolant flows successively through the inlet section 40, intermediate section 44 and outlet section 42 of the passages 28. In the inlet section 40, thin debris present in the coolant flow are wedged in the notches 48 between the vanes 46. Each notch 48 is appropriate for catching debris by a wedging effect, specifically flexible wires. A flexible wire entering the wide lower end of a notch 48 will be wedged in the narrow upper end of the notch 48. The elongated debris are further trapped in the intermediate section 44 due to the non-rectilinear shape of each passage 28. Twisted vanes 46 tend to align the elongated debris passing the vanes 46 with the flow direction F, thus improving trapping of these elongated debris in the intermediate section 44. Besides, the strips 50 dividing each passage 28 into a plurality of channels 51 prevent debris oriented in the second transverse direction T2 to pass through the passages 28. The alternative embodiment illustrated on FIG. 9 differs from that of the embodiment of FIGS. 3-8 in that each plate 26 comprises adjacent vanes 46 twisted in the same direction. The notches 48 have thus a wider lower end. The alternative embodiment illustrated on FIG. 10 differs from that of the embodiments of FIGS. 3-8 in that each plate 26 comprises vanes 46 each bend along its upper end connected to the rest of the plate 26 in a direction such as to project obliquely from a plate face 36 and downwardly. Each plate 26 has adjacent vanes 46 bent in opposite directions: each plate 26 has vanes 46 projecting from a plate face 36 alternating with vanes 46 projecting from the opposite plate face 36. The notches 48 have thus a wider lower end. The alternative embodiment of FIGS. 11 and 12 differs from that of FIGS. 3-10 in that the vanes are replaced by debris catching teeth 60 distributed along each plate 26. The teeth 60 are cut in the lower portion 30 of each plate 26. Each tooth 60 protrudes from one plate face 36, obliquely away from the plate face 36 and downwardly. Each tooth 60 is located in register with a channel 51 delimited between two connection strips 50. Each set of teeth 60 protruding one face 36 of a plate 26 defines a filtering comb in the passage 28 delimited by said face. Each tooth 60 delimits with the lower portion 30 an upwardly tapering space 62 (FIG. 11) for wedging debris between the tooth 60 and the lower portion 30 of the plate 26. As illustrated on FIGS. 11 and 12, the plates 26 comprise teeth 60 protruding one plate face 36 alternating with teeth 60 protruding the opposite plate face 36. In an alternative embodiment, each plate 26 comprises adjacent teeth 60 protruding the same plate face 36. The debris filter of the invention is adapted for Pressurized Water Reactor (PWR) fuel assemblies or Boiling Water Reactor (BWR) fuel assemblies. More generally, it may also be used in any Water Cooled Reactor fuel assembly, for instance for a VVER (Water-Water Energetic Reactor) fuel assembly.
050080709	summary	BACKGROUND OF THE INVENTION The present invention relates to a fuel assembly, and more particularly to a fuel assembly suitable for enhancing fuel utilization, which is to be installed in a boiling water reactor (BWR). Under the condition that a fuel assembly to be used in the BWR is installed in a reactor core, non-saturated cooling water or coolant is flowed between fuel rods through holes of a lower tie plate of the fuel assembly. As the coolant is flowed between the fuel rods from a lower portion thereof to an upper portion thereof, the coolant is heated and boiled to form a two-phase flow to be discharged from holes of an upper tie plate. Therefore, a light water that is neutron moderator is generally distributed so that the amount thereof is decreased from the lower portion to the upper portion within the fuel assembly. Also, it should be noted that the actual distribution of the coolant in the axial direction depends upon the mutual effect with the power distribution. Namely, an average void fraction of the reactor core determined by such distribution controls the neutron moderation effect of the overall reactor core and the power distribution. Recently, in order to realize the effective use of uranium resource and the power cost reduction thereof, it has been proposed to enhance an average enrichment of the fuel assembly to provide a fuel assembly with a high burnup. The high burnup of the fuel assembly causes a burnup reactivity to increase, which is needed for continuing the operation among the reactor during one operational cycle. In the BWR, it has been proposed to control the reactivity mainly by adjusting the amount of burnable poison, i.e., gadolinia and the reactor core average void fraction. This adjustment of the reactor core average void fraction is performed by operating the reactor with a high void fraction during the operational cycle from the initial stage to the nearly end thereof, at which the neutron moderating effect is small, whereby the controlled amount of reactivity is increased by an absorption of neutron into uranium 238. The adjustment is performed, inversely, by using a low void fraction at the operational cycle end. A method for adjusting the reactor core void fraction is called "spectral shift operation". In that method, since plutonium 239 converted from uranium 238 is effectively used as a fuel in the final stage of the operational cycle, such effective use of plutonium 239 as well as the reactivity control effect to enhance the fuel economical property. The spectral shift operation method is divided into a method for changing the flowrate of the coolant during the operational cycle and a method for changing the axial power distribution during the operational cycle. The latter method is disclosed in U.S. Pat. No. 4,587,090. According to this method, a difference in reactivity between the upper region and the lower region of the fuel assembly due to the difference of the enrichment and a difference in reactivity between the upper region and lower region due to the difference of the burnable poison amount are effectively utilized so that the power distribution of the fuel assembly during first half of the reactor operation cycle is deformed downwardly and the power distribution of the fuel assembly during second half of the reactor operation cycle is deformed upwardly. SUMMARY OF THE INVENTION An object of the invention is to provide fuel assembly which is capable of increasing a spectral shift effect without increasing a maximum linear heat generation rate. To this end, according to the present invention, a burnable poison concentration in a lower region of the fuel assembly is lower than that in an upper region thereof. When each of the fuel rods containing the burnable poison is divided into an upper region and lower region, one of the divided regions of the fuel rods containing a maximum burnable poison concentration Gmax and one of the divided regions of the fuel rods containing a minimum burnable poison concentration are located in the lower region of the fuel assembly.
	description	1. Technical Field The present invention relates to a control rod drive mechanism of a nuclear reactor, and more particularly to a method for recognizing the step movement sequence of a control rod drive mechanism of a nuclear reactor which is capable of accurately recognizing the step movement sequence of the control rod drive mechanism, which draws and inserts a control rod of a nuclear reactor, by estimating and calculating a distance between a stator and a rotor. 2. Related Art A control rod drive mechanism of a nuclear reactor serves to adjust an electric output of a nuclear power plant by drawing and inserting a control rod with the use of an electromagnetic force so as to control the nuclear reaction of the nuclear reactor. The control rod is drawn out and inserted in by a step unit (commonly ⅝ inch), and a series of sequence movements, generally up to 6 or 7 movements, should be accomplished for one step movement. If there is a mechanical or electric problem in any of the sequence movements, the control rod is apt to be stopped or slowed down. This is a very important problem because it relates to the safe operation of the nuclear power plant and to the efficient management of nuclear fuel. Thus, the sequence movements are the most essential factor in the design and implementation of the control rod controlling equipment. Recently, a method for signal-processing a waveform of an electric current flowing through a coil is used in order to determine the movements, but this method is disadvantageously sensitive to noise since it uses a differential operation. The present invention is designed while considering such drawbacks of the prior art, and it is an object of the present invention to provide a method for recognizing the step movement sequence of a control rod drive mechanism of a nuclear rod, which method determines whether a rotor is moved by estimating an inductance of an electromagnetic coil from current and voltage flowing through the electromagnetic coil used in the control rod drive mechanism and then calculating the distance between a rotor and a stator, thereby ensuring high reliability while being hardly affected by external factors such as noise. In order to accomplish the above object, the present invention provides a method for recognizing the step movement sequence of a control rod drive mechanism of a nuclear reactor, which method includes the steps of: measuring current and voltage flowing through an electromagnetic coil used in the control rod drive mechanism of the nuclear reactor; calculating the inductance of the coil by use of the measured current and voltage; and calculating a distance between a rotor and a stator of the control rod drive mechanism on the basis of the calculated inductance, and then recognizing the step movement sequence of the control rod drive mechanism on the basis of the calculated distance. Hereinafter, the present invention will be described in more detail referring to the drawings. FIG. 1 is a reproduction of FIG. 11 from U.S. Pat. No. 5,076,996 and shows a control rod drive mechanism to which the method of the present invention is applied. Referring to FIG. 1, the control rod drive mechanism flows an electric current through three coils—a lifting coil 1, a movable gripper coil 3 and a stationary gripper coil 5—according to a predetermined order so that a control rod 7 may be drawn out or inserted in. A lifting magnetic pole 17 and a lifting armature 15 are closely adhered (or collided) and spaced apart so as to change a gap 16 between them. When the lifting magnetic pole 17 and the lifting armature 15 are closely adhered, the gap 16 is almost zero, so that the lifting movement of the lifting armature 15 is certainly conducted. Gaps 14 and 18 of the movable gripper coil 3 and the stationary gripper coil 5, respectively, are also estimated in the same way, and the movement may also be determined according to the estimation. In FIG. 1, the reference numeral 2 designates a lifting armature return spring, reference numeral 4 designates a movable armature return spring, reference numeral 6 designates a latch return spring, reference numeral 8 designates a stationary gripper, reference numeral 9 designates a stationary gripper armature, reference numeral 10 designates a stationary armature return spring, reference numeral 11 designates a stationary gripper magnetic pole, reference numeral 12 designates a movable gripper armature, reference numeral 13 designates a movable gripper, reference numeral 14 designates a gap between the movable gripper armature 12 and the lifting armature 15, reference numeral 16 designates a gap between the lifting magnetic pole 17 and the lifting armature 15, and reference numeral 18 designates a gap between the stationary gripper magnetic pole 11 and the stationary gripper armature 9, respectively. Related to the operation of the control rod drive mechanism, a method for recognizing the step movement sequence of the control rod drive mechanism of the nuclear reactor according to the present invention will be described with reference to FIG. 2, which is a block diagram of a digital signal processing board used to implement the method of recognizing the step of movement sequence of a control rod drive mechanism of a nuclear reactor according to the present invention. First, current and voltage flowing through the electromagnetic coil 35 (FIG. 2) used in the control rod drive mechanism of the nuclear reactor are measured by current measurement unit 36 and voltage measurement unit 37, respectively. After that, the inductance of the coil is calculated by using the measured current and voltage. In the latter regard, a method for calculating the inductance of the coil is now described in detail. FIG. 3 schematically shows the principle of the present invention. In FIG. 3, if a current (i) is applied to the coil 51 (or a rotor), the armature 53 becomes a magnet, and a distance Z decreases due to the attraction force with respect to a magnetic pole (or a stator) positioned above. This may be expressed in a mathematical equation form as follows. Equation ⁢ ⁢ 1 v = ⅆ ( L · i ) ⅆ t + R · i ⁢ ⁢ Equation ⁢ ⁢ 2 ( 1 ) L ⁡ ( z ) = k z ⁡ ( t ) ( 2 ) Equation 1 is a voltage equation according to Kirchhoff's Law, and Equation 2 shows that the inductance of the coil is inversely proportional to the distance between the rotor and the stator, where v is an applied voltage, i is a current flowing through the coil, R is a resistance of the coil, and k is a proportionally constant related to the number of coil turns and the shape of the magnetic pole 52 and armature 53. Equation 1 may be arranged with regard to the inductance L as follows: Equation ⁢ ⁢ 3 L = 1 i ⁢ ∫ t o t ⁢ ( v - Ri ) ⁢ ⁢ ⅆ t ( 3 ) Equation 3 shows that the inductance of the coil may be calculated on the basis of the voltage applied to the coil and the current flowing through the coil. FIG. 2 is a block diagram of a digital signal processing board which is used for gap estimation. As schematically shown in FIG. 2, when the control rod drive mechanism is operated by using a three-phase half-wave rectifier 19 to which alternating current (AC) sources A, B and C are connected, a control signal is provided from digital control equipment 40 for the control rod drive mechanism to a thyristor gate drive 34 via a timer counter 33. The control equipment 40 adopts the step movement sequence recognizing method of the control rod drive mechanism of the nuclear reactor according to the present invention. Control equipment 40 includes an analog-to-digital (A/D) converter 25 for converting analog signals, input by the current measurement unit 36 and the voltage measurement unit 37, into digital signals, a digital signal processor (DSP) 26, a digital logic implementation device (FPGA) 27, a storage device or memory 28, a digital-to-analog (D/A) converter 29 having an output connected to measuring equipment 39 (an oscilloscope or recorder), a serial communication interface or universal asynchronous receiver transmitter (UART) 30, and a timer counter 33. In FIG. 2, reference numeral 31 designates a realtime monitoring device or personal computer (PC) which is capable of storing operational history on a hard disk 32. In FIG. 2, reference numeral 35 designates the electromagnetic coil. In the digital control equipment 40 for a control rod drive mechanism, data received from the current measurement unit 36 and the voltage measurement unit 37 is converted into a digital signal by the A/D converter 25, and the digital signal processor 26 calculates an inductance L by using the digital values of voltage and current converted by the A/D converter 25 in accordance with Equation 3. Then, a distance Z between the rotor and the stator may be estimated with the use of the calculated inductance L and Equation 2, and the distance Z makes it possible to recognize the step movement sequence of the control rod drive mechanism. Substantially, the gaps 14, 16 and 18 between three rotors and three stators are respectively closely adhered and spaced apart according to the existence of an applied current when the control rod 7 is driven (see FIG. 1). Thus, by using the aforementioned method of the present invention, by measuring the distance between the rotor and the stator in real time, it can be determined whether the gaps 14, 16 and 18 are relatively small or large, respectively. As a result, it is also possible to easily recognize whether the step movement of the control rod drive mechanism is actually generated. Equation 3 is numerically very stable since it uses integral calculus. In addition, if a simple filter is applied to an integral term, it is possible to reduce the influence of external noise and residual deflection in a simple way. This method may be very easily implemented using an A/D converter and a microprocessor. FIGS. 4 to 6 show a simulated result for the gap 16 between the lifting magnetic pole 17 and the lifting armature 15 in the control rod drive mechanism of FIG. 1, which uses various constants as shown in Table 1. TABLE 1Applied voltage100 VInductanceMaximum gap (16 mm)45 mHMinimum gap (0.1 mm)60 mHResistance1.3 ΩWeight of electromagnet130 kg FIG. 4 shows a current flowing through the coil when 100V of voltage is applied to the electromagnetic coil, and FIG. 5 shows a distance (or a gap) between the electromagnet and the magnetic pole, which is reduced due to the attraction force created by the current in the coil. In addition, FIG. 6 shows the inductance L calculated on the basis of the voltage and current at that time. FIGS. 7 and 8 are graphs of waveforms which result from the gap estimation test at the lifting coil of a simulated control rod drive mechanism by using the digital signal processor of FIG. 2. FIGS. 7 and 8 show estimated results of the gap 16 between the lifting magnetic pole 17 and the lifting armature 15 of FIG. 1. In FIGS. 7 and 8, the upper waveform denotes a coil current, and the lower waveform denotes an estimated gap (16 mm, 0 mm, 16 mm), respectively. In addition, FIG. 7 relates to the case wherein the control rod is drawn out, and FIG. 8 relates to the case wherein the control rod is inserted. As described above, the method for recognizing the step movement sequence of a control rod drive mechanism of a nuclear reactor according to the present invention determines whether a rotor is moved by estimating an inductance of the coil from the current and voltage of the electromagnetic coil, and then calculating a distance between the rotor and the stator on the basis of the estimated inductance. Thus, the present invention ensures good reliability for determination, allows easy implementation using a digital signal processor, and is hardly affected by external factors such as noise. Although preferred embodiments of the present invention have been described, it will be understood by those skilled in the art that the present invention should not be limited to the described preferred embodiments. Rather, various changes and modifications can be made within the spirit and scope of the present invention, as defined by the following claims.
044143397	claims	1. An ELM absorption composition comprising (1) a solid dielectric material having dispersed therein (2) a colloidal-size particulate having a maximum dimension less than about 1 micrometer of an absorber for electromagnetic radiation and (3) a particulate of an attenuator for electromagnetic radiation, said composition further characterized by having a density less than 6 grams per cubic centimeter (g/cm.sup.3) and substantially all of the particles of the absorber being maintained in a spaced apart relationship by the solid dielectric. 2. The composition of claim 1 wherein the composition exhibits a magnetic loss tangent greater than 0.05 and an ELM attenuation of greater than 0.5 decibels per centimeter (dB/cm) when the composition having a thickness of 2 centimeters is exposed to electromagnetic radiation having a frequency of 2 gegahertz. 3. The composition of claim 2 which has a density in the range from about 1.5 to about 3 g/cm.sup.3 and exhibits a magnetic loss tangent greater than 0.2 and an attenuation greater than 2 dB/cm. 4. The composition of claim 2 wherein the absorber is an oxide of a magnetic metal and the attenuator is a magnetic metal or an alloy containing at least one magnetic metal. 5. The composition of claim 4 wherein the magnetic metal is iron. 6. The composition of claim 5 wherein the absorber is Fe.sub.3 O.sub.4 having a maximum particle dimension less than 1 micrometer and the attenuator is carbonyl iron having an average particle size greater than 1 micrometer. 7. The composition of claim 6 wherein Fe.sub.3 O.sub.4 has a maximum particle dimension in the range from 0.01 to about 0.7 micrometer and the carbonyl iron has an average particle size in the range from about 2 to about 40 micrometers. 8. The composition of claim 7 comprising from about 90 to about 15 weight parts of a dielectric synthetic thermoplastic and from about 10 to about 85 weight parts of combined absorber and attenuator wherein the weight ratio of absorber to attenuator is from about 90:10 to about 60:40. 9. The composition of claim 8 wherein the synthetic thermoplastic is a styrene/butyl acrylate copolymer. 10. The composition of claim 8 wherein substantially all of the particles of the absorber and attenuator are maintained in a discrete spaced apart relationship by the thermoplastic. 11. The composition of claim 1 in the form of an aqueous dispersion of (A) the solid dielectric material having the absorber particulate dispersed therein and (B) the attenuator particulate. 12. The composition of claim 1 wherein the absorber particulate has an average particle diameter within the range of from about 0.05 to about 0.1 micrometer.
	summary
	abstract	One embodiment relates to a dynamic pattern generator for controllably reflecting charged particles. The generator includes at least a controllable light emitter array, an optical lens, and an array of light-sensitive devices. The controllable light emitter array is configured to emit a pattern of light. The optical lens is configured to demagnify the pattern of light. The array of light-sensitive devices is configured to receive the demagnified pattern of light and to produce a corresponding pattern of surface voltages. Other embodiments and features are also disclosed.
	summary
050646060	description	DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, and particularly to FIG. 5, there is illustrated a front elevational view of a channel box removing apparatus of the present invention generally designated by the numeral 70. As shown, the channel box removing apparatus 70 comprises a frame structure 72 including four elongated, upright, angular support members 74 defining four corners thereof; and a lifting rod 76 mounted to and extending upwardly from the top of the frame structure 72. The lifting rod 76 is normally connected to the lower end of a suspension wire 78 by means of a spring-loaded shock absorber 80 and a cable terminal fitting 82. The suspension wire 78 is connected to an auxiliary hoist, crane or the like (not shown). As seen in FIGS. 5, 6 and 8, the channel box removing apparatus 70 includes a pair of releasable hooks 84 adapted to engage the undersurfaces of clips 86 provided adjacent a pair of diagonally opposed top corners of the channel box 12. Each of the releasable hooks 84 has an upper end pivotally mounted by a pin 88 on the lower portion of the frame structure 72 and a lower end extending downwardly from the bottom of the frame structure. The removal apparatus also includes a bifurcated bracket 90 which is pivotally connected to the releasable hooks 84 by pins 92 in a manner to straddle the hook pair, as best seen in FIGS. 8A and 8B. Vertical movement of the bracket 90 results in the movement of the pair of releasable hooks 84 between an unlatched position (FIG. 8A) and a latched position (FIG. 8B). The channel box removing apparatus 70 also includes a pneumatic control mechanism 94 for controlling the movement of the releasable hooks 84, which comprises a double-acting pneumatic cylinder 96 mounted substantially in the center of the removal apparatus, a piston rod 98 having its lower end operatively connected to the bracket 90, and resilient air hoses 100 leading from two chambers of the pneumatic cylinder 96. The resilient air hoses 100 are in turn connected at their respective upper ends to connector plugs 102. A hand lever 104 having a ring end is provided which permits forced disengagement of the releasable hooks 84 from the channel box. The hand lever 104 is rotatably mounted at the other end to the frame structure 72 by means of a pin 106 (FIG. 9) and also is pivotably connected adjacent the other end to the upper end of a piston rod 108 by a pin 110 (FIG. 9). The channel box removing apparatus 70 includes a bail cap 112 which is adapted for placement on a bail 114 provided on an upper tie plate of the nuclear fuel assembly. The bail cap 112 comprises a pair of spaced support members 116 provided in opposed relationship to each other and having a vertically extending guide slot 118 defined therebetween to slidably receive the bail 114, a connector member 120 securely connecting the pair of support members 116 in their middle portions and adapted for abutting engagement with the top of the bail 114, and a pair of bail guides 122 extending downwardly and outwardly from the bottom ends of the respective support members 116 and having their open lower edges adapted to abut the upper ends of the channel box 12 adjacent a pair of diagonally opposed corners thereof which are different from the pair of corners having the clips 86 provided thereon. The bail cap 112 is provided on the removing apparatus for vertical movement along a guide groove 124 defined in the lower portion thereof. Referring to FIGS. 6 and 8, there is provided a locking mechanism 126 for locking the releasable hooks 84 in the latched position, i.e., in engagement with the undersurfaces of the associated clips 86 of the channel box 12. The locking mechanism 126 includes a pair of swing plates 128 which can selectively double the range of pivotal movement of the releasable hooks 84 and which are pivotally mounted adjacent their upper ends to the frame structure 72 by pins 130. A pin 132 projecting from each releasable hook 84 is loosely received in a slit 134 formed in the swing plate 128 to permit a swinging movement of the lower end of the swing plate 128 beyond the pivotal range of the releasable hook 84. Each swing plate 128 has a stopper pin 136 provided at its lower end. The bail cap 112 has a pair of stopper members 138 integrally formed on the side surfaces thereof. Each stopper member 138 has a groove indicated by phantom lines which can be engaged by the associated stopper pin 136 when the associated releasable hook 84 is in its unlatched position as shown in FIG. 8(A). When the associated releasable hook 84 is in its latched position with the bail cap 112 slightly lowered relative to the removal apparatus, the stopper pin 136 abuts the stopper member 138. Referring to FIG. 9, there is provided a first indicator mechanism 140 which comprises a red indicator plate 142 in the shape of a right-angled equilateral triangle, the indicator plate 142 being pivotally mounted adjacent its bottom end to the top of the frame structure 72 for swinging movement between an upright and a horizontal position, an actuator link 144 pivotally mounted at its middle portion to the frame structure, the actuator link 144 being engagable with the bail cap 112 in the guide groove 116 provided in the lower portion of the removal apparatus, and a control rod 146 having opposite ends pivotally connected to the rear face of the red indicator plate 142 and one end of the actuator link 144, respectively. The control rod 146 comprises a lower portion 146a, and an upper portion 146b adapted to be vertically moved relative to the lower portion 146a. The upper portion 146b is biased downwardly by a spring 148 and includes a pin 150 provided in the middle portion thereof which causes vertical movement of the upper portion 146b in response to the movement of the hand lever 104 because of its engagement with the pin 150. The lower portion 146a is biased upwardly by a spring 152, the upper end of the lower portion 146a being in engagement with a stopper 154 on the upper portion 146b normally, i.e., when the bail cap 112 is out of engagement with the actuator link 144. Accordingly, with the bail guides 122 of the removal apparatus 70 resting in place on the diagonally opposed corners of the channel box 12, further lowering of the removal apparatus relative to the bail cap 112 until the unlatched hooks 84 are inserted into the channel box 12 will bring the bail cap 112 into engagement with the lower end of the actuator link 144. This will rotate the actuator link 144 in a counter-clockwise direction as viewed in FIG. 9 and accordingly move the lower portion 146a downwardly against the action of the spring 152. In this condition, the piston rod 108 can be lowered by actuation of the pneumatic cylinder 96 to move the releasable hooks 84 to the latched position where they engage the undersurfaces of the associated clips 86 of the channel box 12. This will cause a downward movement of the upper portion 146b by the action of the spring 148, rotating the hand lever 104 in a counter-clockwise direction as viewed in FIG. 9 because of its engagement with the pin 150. As a result, the red indicator plate 142 is moved to its horizontal position indicating that the pair of releasable hooks 84 are in the latched position. Referring to FIG. 10, there is provided a second indicator mechanism 160 comprising a yellow indicator plate 162 in the shape of a right-angled equilateral triangle also, the plate 162 being pivotally mounted adjacent its bottom end to the top of the removal apparatus 70 on the opposite side to the red indicator plate 142 so that the yellow indicator plate 162 can swing between its upright and horizontal positions. The second indicator mechanism 160 also includes an actuator link 164 having its upper end pivotally connected to the yellow indicator plate 162, the lower end of the control rod 164 slidably extending through the guide groove 124 in the lower portion of the removal apparatus and an aligned groove of the bail cap 112 into the vertically extending guide slot 118. The yellow indicator plate 162 normally assumes the horizontal position under the action of the weight of the actuator link 164. However, in lowering the removal apparatus 70, when the lower edges of the bail guide 122 first comes into abutting engagement with the associated corners of the channel box 12, followed by the bail 114 of the channel box 12 being received in the bail cap 112, the bail cap 112 will move upwardly relative to the removal apparatus, causing the bail 114 to come into abutting engagement with the lower end of the control rod 164. As a result, the control rod 164 is moved upward to rotate the yellow indicator plate 162 in a counter-clockwise direction as viewed in FIG. 10 to the upright position. When the releasable hooks 84 are moved to the latched position to engage the undersurfaces of the associated clips 86 of the channel box 12, lifting of the removal apparatus will move the channel box 12 upwardly relative to the fuel assembly proper 14 and, at the same time, cause lowering of the bail cap 112 relative to the removal apparatus. As a result, the bail 114 is disengaged from the actuator link 164, causing the yellow indicator plate 162 to swing to the horizontal position under the action of the weight of the actuator link 164. It should thus be noted that when the yellow indicator plate 162 is in the upright position, it provides a visual indication that the bail cap 112 is in the position to fully receive the bail 114. When the yellow indicator plate 162 is in the horizontal position, it indicates that the channel box 12 can be pulled up separately from the fuel assembly. Referring to FIGS. 11(A) and 11(B), there is shown a guide unit 170 removably mounted to the bail cap 112 to facilitate guidance of the removal apparatus into its operative position with the fuel assembly from which the channel box is to be removed. The guide unit 170 comprises a pair of conical guide rollers 172 rotatable about a common horizontal axis, and a pair of support members 174 having their lower ends rotatably supporting the guide rollers 172. The pair of support members 174 of the guide unit 170 are removably and rotatably mounted to the lower end of the bail cap 112 by connector pins or ball lock pins 176. As best seen in FIG. 11(B), the pair of guide rollers 172 can slidably and rotatably engage a pair of diagonally opposed corners of the channel box 12 having no clips attached thereto. It will be appreciated by those skilled in the art that this guide unit can conveniently be used in hoisting and transfering channel boxes separated from their associated fuel assemblies. Removal of the channel box from the associated fuel assembly using the removal apparatus of the present invention is accomplished during refuelling, as follows: (1) About 200 spent fuel assemblies previously transferred from a reactor core (not shown) onto the fuel rack 40 within the spent fuel storage pool 41 are lifted by the main hoist 42 on the refuelling platform car 44 for transfer to the preparation machine 46. (2) At the preparation machine 46, the fastener bolts 16 threaded into the associated clips 86 to secure the channel box to the fuel assembly proper are removed by a conventional bolt wrench (not shown) which is about four meters long. (3) After removal of the fastener bolts, the nuclear fuel assembly is transferred by the main hoist 42 from the preparation machine 46 back to the fuel rack 40. (4) The channel box removing apparatus 70 is suspended from the cable terminal end of the auxiliary hoist 56 and is lowered onto the nuclear fuel assembly placed in the fuel rack 40. Then the channel box 12 is pulled up from the nuclear fuel assembly to be separated therefrom by the auxiliary hoist 56 and is transferred to an unoccupied location in the fuel rack. It will be appreciated that the above steps (1) to (4) of channel box removal are much simpler and less time consuming than the conventional steps (1) to (5) as described above. If a long bolt wrench, e.g., 10 meters long, such as one disclosed in, applicant's copending U.S. application, Ser. No. 07/501,107, entitled: "Bolt Wrench" is used, the step (1) of transferring the nuclear fuel assembly from the fuel rack to the preparation machine as well as the step (3) of transferring the nuclear fuel assembly with the fastener bolts removed from the preparation machine back to the fuel rack can be dispensed with. Now, the manner in which the channel box is separated from the fuel assembly in step (4) will be described in more detail: The removal apparatus of the invention is gradually lowered onto the fuel assembly 10 on the fuel rack 40. During lowering of the removal apparatus, the bail 114 of the upper tie plate of the unclear fuel assembly 10 serves to guide the bail guide 122 of the removal apparatus 70 into a position where the bail cap 112 completely covers the bail 114 while simultaneously the lower edges of the bail guides 122 rest on the top of the channel box 12. Further lowering of the removal apparatus 70 will move the bail cap 112 upwardly relative to the apparatus and cause the pair of releasable hooks 84 to be inserted into the channel box 12. This will cause the bail 114 to move the control rod 164 upwardly, resulting in a swinging movement of the yellow indicator plate 162 to the upright position. In the upright position, the red indicator plate 142 is not visible from just above. Now, the pneumatic cylinder 96 may be activated to move the piston rod 108 downwardly so as to move the pair of releasable hooks 84 into the latched position where the hooks are in lifting engagement with the associated clips 86 of the channel box 12. When the piston rod 108 moves downwardly, the upper portion 146b of the actuator link 146 also is moved downwardly by the action of the spring 148, because the upper portion 146b is operatively connected with the piston rod 108 via the pin 110, the hand lever 104 and the pin 150. Accordingly, the red indicator plate 142 swings to the horizontal position so that the red indicator plate is visible from just above. Next, the removal apparatus 70 is lifted by the auxiliary hoist 56 relative to the bail cap 112 which rests on the channel box 12. This will cause the stopper pins 136 on the pair of releasable hooks 84 to engage the associated stopper members 138 as shown in FIG. 8(B) so that the releasable hooks 84 are effectively locked to prevent their disengagement from the associated clips 86 on the channel box 12 even in the event of a malfunction of the pneumatic cylinder 96, for example. As the removal apparatus 70 is further lifted, the channel box 12 is moved upwardly separately from the nuclear fuel assembly proper 14. This will disengage the lower end of the control rod 164 from engagement with the bail 114 and accordingly cause the yellow indicator plate 162 to swing to the horizontal position under the action of the weight of the control rod 164. In the horizontal position, the yellow indicator plate 162 is visible from just above. It should be noted that the second indicator mechanism 160 provides a visual indication that the channel box 12 has been removed from the nuclear fuel assembly 14. The removal apparatus 70 carrying the channel box 12 is then moved to a position above an intended location in the spent fuel storage pool 41, normally the fuel rack 40, where it is lowered until the channel box reaches the bottom of the fuel rack. When the removal apparatus 70 is further lowered relative to the channel box 12, the stopper pins 136 disengage from the associated stopper members 138. In this condition, the pneumatic cylinder 96 is activated to move the piston rod 108 upwardly so as to move the pair of releasable hooks 84 into the unlatched position as shown in FIG. 8(A). As shown, the pair of releasable hooks 84 are out of engagement with the associated clips 86, so that the removal apparatus 70 can be lifted separately from the channel box 12. It will be appreciated that the hand lever 104 provides an emergency disconnect mechanism for moving the pair of releasable hooks 84 into the unlatched position in the event of a malfunction of the air supply system including a faulty air source or air hoses. That is, if difficulties are experienced in releasing or disengaging the pair of hooks 84 from the clips 86 of the channel box 12, the hand lever 104 may be moved upwardly by hooking the ring portion by suitable means and lifting it to move the piston rod 108 upwardly to thereby unlatch the pair of releasable hooks 84. It will be appreciated that in accordance with the teachings of the present invention there has been provided an improved apparatus for removing a channel box from a nuclear fuel assembly in an efficient and reliable manner. To recapitulate the important features of the invention: (1) The invention can simplify the channel box removal operation by eliminating certain transfer steps which were necessary if the removal apparatus of the conventional type is used. This provides additional advantages of a reduced operation time, a decreased operator's exposure to radioactivities, and a reduced possibility of damage to fuel assemblies during transfer. (2) The provision of the lock mechanism prevents accidental release of the pair of releasable hooks 84 with the consequential fall of the channel box 12, as the releasable hooks cannot be disengaged from the associated clips 86 so long as the stopper pins 136 are in engagement with the stopper members 138 as shown in FIG. 8(B). (3) The use of the first and second indicator mechanisms 140 and 160 provides visual indications that the removal apparatus 70 is in lifting engagement, or out of engagement with the channel box 12, respectively. When the red indicator plate 142 is in the horizontal position, it indicates that the removal apparatus 70 can be lifted to separate the channel box from the fuel assembly proper 14 as the pair of releasable hooks 84 are in positive engagement with the clips 86 of the channel box. On the other hand, when the yellow indicator plate 162 is in the horizontal position, it indicates that the pair of releasable hooks 84 are out of engagement with the associated clips 86 so that the removal apparatus can be lifted separately from the channel box. This enables various underwater operations within the spent fuel storge pool to be performed efficiently and reliably by remote control. Although the present invention has been described in terms of what are at present believed to be its preferred embodiments, it will be apparent to those skilled in the art that various changes may be made without departing from the scope of the invention. It is therefore intended that the appended claims cover such changes.
	abstract	Provided is a apparatus for sensing a liquid level reliably based solely on an analog process even if a liquid held in a container boils, causing the liquid level to fall. A liquid level sensing apparatus includes: a probe selection unit configured to select a probe whose heater is to be activated from among the plurality of probes; an input unit configured to receive an output of the temperature sensor of the probe selected by the probe selection unit, the output being received as a temperature signal directly in the form of an analog quantity; a signal processing unit configured to output a processing signal of the temperature signal in synchronization with activation of the heater; a calculation unit configured to arithmetically process the temperature signal and the processing signal and output a result; a gas/liquid discrimination unit configured to discriminate whether the detecting point exists in a gas phase or a liquid phase based on the output result of the arithmetic processing; and a display unit configured to indicate a discrimination result produced by the gas/liquid discrimination unit.
039719502	description	DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows an x-ray cassette and subject in position for a craniocaudad view of the subject's breast, the breast being properly positioned and compressed by the independent compression device 10 of the present invention. The compression device 10 is attached to a flat surface 12 which may be independent of the x-ray system or on the x-ray table itself. Compression device 10, in essence, comprises a compression paddle 14 made of transparent, radio-translucent, material, such as "Lexan," a polycarbonate organic resin from General Electric Company, which allows the user, or technologist, to visually confirm the position of the breast prior to x-ray exposure, insure maximum compression and eliminate skin folds to provide images of improved quality while reducing the necessity for reimaging. A vacuum base 16 having a vacuum base lock and release lever 18 is secured to the supporting surface 12, square shaped post member 20 being rotatably supported in base 16 via a bushing 22. The compression paddle 14 is supported in slide assembly 24 via paddle support arm 26. Knob 28 is provided to allow the device (except the vacuum base 16) to rotate in a horizontal plane. Vertical pressure release member 30 allows control of the vertical position of the compression paddle 14 along post member 20. Knob 32 allows the paddle 14 to rotate around support arm 26 thereby providing adjustment of the paddle position for the exaggerated medial and lateral craniocaudad views and accommodating subjects with stomach protrusions and prominent rib cages in the lateral views and allowing an in and out motion for proper location of the paddle 14 directly against the chest wall. Lever 32 provides a tilting type movement for the compression paddle which allows for maximum compression in the thick part of the breast. Compression paddle 14 comprises an upwardly curved lip portion 35 and side members 36 and 38. To allow the compression paddle 14 to apply maximum compression (pressure) in the area of the breast near the chest wall (retromammary area) with minimum compression in the nipple area (subareolar area), the lower surface 40 of the compression paddle 14 has a uniquely designed curved shape as shown. Although the subject to be examined is shown positioned for the craniocaudad and contact medio-lateral views in FIGS. 1 and 2, respectively, the positioning flexibility of the independent compression device of the present invention due to the degrees of freedom associated with the positioning of the compression paddle 14 allows additional supplementary views to be imaged. As shown in FIGS. 1 and 2, the breast of the subject is positioned between the lower surface 40 of the compression paddle 14 and an imaging member holder or cassette 42. The cassette 42 is of the type described in U.S. Pat. No. 3,827,072 which has a charged xerographic plate contained therein. Alternately, the cassette 42 may comprise a standard x-ray film in a paper pack or cassette. The independent compression device, it should be noted, may be utilized with xeroradiographic and film mammographic systems. In operation, a xerographic plate is first charged and then inserted in the cassette 42, the cassette thereafter being positioned as shown in FIGS. 1 and 2. After the user or technologist adjusts independent compression device 10 to properly position and compress the breast, the x-ray source (not shown) is energized and an image of the breast is formed on the xerographic plate. The cassette is then removed and the image is developed. Apparatus for automatically charging the xerographic plate and developing the image formed therein is set forth in U.S. Pat. No. 3,640,246. In the contact medio-lateral view shown in FIG. 2, the cassette 42 rests on the arm of the subject at an angle to surface 12 with compression plate 14 positioned as shown. FIG. 3 is a perspective view of the independent compression device of the present invention and illustrates the adjustable positions of the compression paddle 14. The same reference numerals, it should be noted, are utilized to identify the identical elements in each figure. By appropriate adjustment of knob 28, the entire independent compression device 10, except for vacuum base 16, is rotatable around the horizontal (in direction of arrow 50). This rotation allows for proper compression for exaggerated medial and lateral craniocaudad view and for different thicknesses of the breast in the lateral view. Adjustment of lever 34 allows the compression paddle 14 (and support arm 26, paddle clamp 33, knob 32 and lever 34) to tilt in the direction of arrow 56 whereby maximum compression can be applied to the thick part of the breast. By pressing vertical pressure release member 30, slide assembly 24 is movable in the direction of arrow 58 which allows for compression of the breast and adjustment for different breast sizes. FIG. 4 is a side view of the independent compression device of the present invention and FIG. 5 is a sectional view of FIG. 4 along line 5--5. As set forth hereinabove, the square post member 20 is rotatably mounted to base 16 via bushing 22. The base member 16 and the vacuum base lock and release lever 17 operate to provide a suction connection to a flat surface. A flat head screw 60 joins the compression paddle 14 to support arm 26. The compression paddle 14 is made of a transparent, x-ray transmissive material, such as Lexan, and comprises two edge members 36 and 38 (FIGS. 1 and 2) and a lower surface of a predetermined curvature. As set forth hereinabove, the curved design for the compression paddle allows slightly greater pressure to be exerted on the chest wall than on the area closer to the nipple therefore providing an object of essentially constant thickness variation which provides higher quality images. The paddle curvature also allows the breast to be positioned away from the chest wall, aiding in the separation of structures within the breast and minimizes subject discomfort during the examination. Although the particular curvature and other paddle dimensions may be varied, the following are typical of those which may be utilized to provide the advantages set forth hereinabove: a = 0.035 inches PA1 b = 0.750 inches PA1 c = 2.72 inches PA1 d = 1.60 inches PA1 e = 6.76 inches PA1 f = 2.64 inches PA1 g = 6.77 inches PA1 R.sub.a = 2.77 inches PA1 R.sub.b = 2.87 inches PA1 R.sub.c = 15.50 inches PA1 .theta. = 26.degree. Referring now to the sectional view shown in FIG. 5, a tensioning rod 62 having internal threads therein is mounted inside hollow post member 20. A screw 64 is threadedly coupled to tension rod 62 through the upper surface of base member 16. A washer 66 is interposed between the screw head 68 and the surface of base 16. A female knob 28 is threadedly affixed to the other end of tension rod 62. The slide assembly 24 is formed around post member 20 and is movable in a vertical direction. FIG. 4 shows the vertical pressure release member 30 in a position wherein the slide assembly 24 is maintained in a selected position. Depression of the lever will allow the slide assembly 24 to move freely in the vertical direction to the selected position at which point the lever is released, locking the assembly to the selected position. A paddle clamp mounting 70 is provided adjacent one side of the slide assembly 24, paddle support arm 34 being inserted in the aperture formed therein. The paddle support arm 34 is separated from the slider assembly 24 by washer 72. The lever assembly 34 includes an internal threaded post 74 which extends through an aperture in paddle clamp mounting 70 and extends through an aperture in the slide assembly 24. A washer 26 is interposed between the lever head and one surface of paddle clamp mounting 70. Internal threaded post, or screw set, 78 is affixed at one end to knob 32, the other end engaging the surface of slide assembly 24 as shown. The manner of adjusting the independent compression device 10, and the compression paddle 14, in particular, has been set forth hereinabove with reference to FIG. 3. The independent compression device set forth hereinabove is independent of the x-ray system being utilized, is lightweight and portable and includes a compression paddle made of transparent plastic which allows the user to visualize breast position and eliminate skin folds prior to x-ray exposure, reducing the number of reimages which normally may be necessary. The compression paddle is adjustable in a number of directions providing positioning flexibility which allows improved images to be produced because of the control on paddle position. The unique curved design of the lower surface of the compression paddle in addition gently holds the opposite breast out of the image area, the paddle being comfortable and smooth against the breast to be imaged. While the invention has been described with reference to its preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the true spirit and scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teaching of the invention without departing from its essential teachings.
054188237	claims	1. A system for determining the thickness of a metallic liner or coating provided at an inner surface of a metal tube, comprising: an electromagnetic eddy-current inducing impedance measurement subsystem, having a non-invasive eddy-current inducing probe, for externally determining an inside diameter of said tube; an ultrasonic dimensional measurement subsystem for determining an inside diameter of said tube; a memory for storing measurement data provided by said electromagnetic and ultrasonic subsystems; and an arithmetic processing unit, connected to said ultrasonic and electromagnetic subsystems and to said memory, for calculating the thickness of said liner, said calculations based on said measurement data of said tube inside diameter acquired from both of said measurement subsystems. a) measuring, using an electromagnetic eddy-current-inducing impedance measuring arrangement, and storing as a set of calibration reference values in said memory, a plurality of impedances corresponding to lined tubes of predetermined combinations of known inside diameters, outside diameters and lining thicknesses, including a first subset of reference values consisting of impedances measured from lined tubes having the same lining thickness but different inside and outside diameter dimensions, and further including a second subset of reference values consisting of impedances measured from lined tubes having the same inside and outside diameters but different lining thicknesses; b) storing in said memory a predetermined reference value for the thickness of a lining corresponding to said first subset of reference values; c) measuring an impedance of a tube specimen under test, using said electromagnetic measuring arrangement, and storing said value in said memory; d) determining a first inside diameter value of said specimen tube using conventional eddy-current analysis computational techniques and storing said first inside diameter value in said memory; e) analyzing said specimen tube and determining a second inside diameter value of said specimen tube by conventional ultrasonic diagnostic techniques and storing said second inside diameter value in said memory; and f) calculating a value for a thickness of said specimen tube lining based on said stored calibration reference values for impedances, said reference value for lining thickness, said measured impedance of said specimen tube and the difference between said first and second inside diameter values. correlating differences in tube inside diameters for tubes with identical lining thicknesses to changes in impedance from said calibration reference values; and correlating differences in tube lining thickness for tubes with identical inner and outer diameter dimensions to changes in impedance, as measured by said electromagnetic measuring arrangement, from said calibration reference values. passing said specimen tube through the center of an eddy-current-inducing impedance measurement coil to a point along the length of said tube where said liner thickness is to be determined and obtaining an external impedance measurement thereat. a) measuring an impedance of a tube specimen under test using an electromagnetic eddy-current-inducing measuring arrangement; b) determining a first inside diameter value of said specimen tube using conventional eddy-current analysis computational techniques; c) analyzing said specimen tube by conventional ultrasonic diagnostic techniques and determining a second inside diameter value of said specimen tube; and d) calculating a value for a thickness of said specimen tube lining based on said calibration reference values, said reference value for lining thickness, said measured impedance of said specimen tube, and the difference between said first and second inside diameter values. T.sub.b =calculated value of lining thickness; T.sub.std =reference value for lining thickness; E.sub.1 =a calibration reference value that correlates differences in tube inside diameter to changes in impedance as measured by the electromagnetic measuring arrangement; E.sub.2 =a calibration reference value that correlates differences in tube lining thickness to changes in impedance as measured by the electromagnetic measuring arrangement; ID.sub.ut =Inside diameter determined ultrasonically; and ID.sub.ec =Inside diameter determined by electromagnetically. correlating differences in tube inside diameters for tubes with identical lining thicknesses to changes in impedance from said calibration reference values; and correlating differences in tube lining thickness for tubes with identical inner and outer diameter dimensions to changes in impedance, as measured by said electromagnetic measuring arrangement, from said calibration reference values. passing said specimen tube through the center of an eddy-current-inducing impedance measurement coil to a point along the length of said tube where said liner thickness is to be determined and obtaining an impedance measurement thereat. a non-invasive eddy-current-inducing diagnostic means for determining an inside diameter of said tube, said eddy-current-inducing means operative to determine said inside diameter from outside of said tube; a non-eddy-current-inducing diagnostic means for determining an inside diameter of said tube; and an electronic digital computer, connected to said eddy-current-inducing diagnostic means and to said non-eddy-current-inducing diagnostic means, for calculating a thickness of said liner based on reference data stored in said computer and measurement data of said tube inside diameter acquired by said computer from both of said diagnostic means. T.sub.b =calculated value of liner thickness; T.sub.std =a calibration reference data value for a standard liner thickness; E.sub.1 =a calibration reference data value that correlates differences in tube inside diameter to changes in impedance as measured by said eddy-current-inducing diagnostic means; E.sub.2 =a calibration reference data value that correlates differences in tube lining thickness to changes in impedance as measured by said eddy-current-inducing diagnostic means; ID.sub.nec =Inside diameter determined by non-eddy-current-inducing diagnostic means; and ID.sub.ec =Inside diameter determined by eddy-current-inducing diagnostic means. 2. A system as set forth in claim 1 wherein said electromagnetic impedance measurement subsystem includes a differential coil eddy-current probe arrangement comprising an eddy-current-inducing impedance measurement coil for measuring an impedance from outside of a specimen metal tube by passing said specimen tube through the center of an eddy-current-inducing impedance measurement coil to a point along the length of said tube where said liner thickness is to be determined. 3. A system as set forth in claim 1 wherein said arithmetic processing unit is connected to a printer. 4. A system as set forth in claim 1 wherein said arithmetic processing unit is integral to said electromagnetic impedance measurement subsystem. 5. In a combined ultrasonic and eddy-current nondestructive testing arrangement having a memory for storing measurement and reference data and an arithmetic processor for performing calculations on said data, a method for determining thickness of metallic linings and metallic coatings provided at an inside surface of a metal tube, comprising the steps of: 6. The method as set forth in claim 5, wherein said step of calculating a value for a thickness of said specimen tube lining further includes steps of: 7. A method as set forth claim 5, wherein said electromagnetic impedance measuring arrangement includes a differential coil eddy-current probe arrangement comprising a non-invasive eddy-current-inducing impedance measurement coil for measuring an impedance from outside of said metal tube, and said step of measuring an impedance of a tube specimen under test, includes: 8. A method for determining thickness of metallic linings or coatings provided at an inside surface of a metal tube, using a set of calibration reference values comprising a plurality of impedance values corresponding to impedances, measured via an electromagnetic eddy-current-inducing measuring arrangement, of lined tubes of predetermined combinations of known inside diameters, outside diameters and lining thicknesses, including a first subset of reference values consisting of calibration impedances measured from lined tubes having the same lining thickness but different inside and outside diameter dimensions, and including a second subset of reference values consisting of calibration impedances measured from lined tubes having the same inside and outside diameters but different lining thicknesses, and further including a predetermined reference value for the thickness of a lining corresponding to said first subset of reference values, comprising the steps of: 9. The method as set forth in claim 8, wherein said value for lining thickness is calculated according to the following formula: EQU T.sub.b =T.sub.std +E.sub.1 /E.sub.2 .times.(ID.sub.ut -ID.sub.ec) 10. The method as set forth in claim 8, wherein said step of calculating a value for a thickness of said specimen tube lining further includes steps of: 11. A method as set forth claim 8, wherein said electromagnetic impedance measuring arrangement includes a differential coil eddy-current probe arrangement comprising a non-invasive eddy-current-inducing impedance measurement coil for measuring an impedance from outside of said metal tube, and said step of measuring an impedance of a tube specimen under test, includes: 12. An apparatus for determining the thickness of a metallic liner provided at an inner surface of a metal alloy tube, comprising: 13. A apparatus as set forth in claim 12, wherein said eddy-current-inducing diagnostic means includes a differential coil eddy-current probe arrangement comprising an eddy-current-inducing impedance measurement coil for measuring an impedance from outside of said tube by passing a specimen tube through the center of an eddy-current-inducing impedance measurement coil to a point along the length of said tube where said liner thickness is to be determined. 14. An apparatus as set forth in claim 12, wherein a liner thickness, T.sub.b, is calculated by said digital computer according to the following formula: EQU T.sub.b =T.sub.std +E.sub.1 /E.sub.2 .times.(ID.sub.nec -ID.sub.ec) 15. A system as set forth in claim 2 wherein said differential coil eddy-current probe arrangement further comprises a load balancing reference coil. 16. An apparatus as set forth in claim 13, wherein said differential coil eddy-current probe arrangement further comprises a load balancing reference coil, said reference coil surrounding a reference metal tube section.
	abstract	A composite nuclear reactor component comprises a support and a protective layer (2). The support contains a substrate (1) based on a metal. The substrate is coated with an interposed layer (3) positioned between the substrate (1) and the protective layer (2). The protective layer (2) is composed of a material which comprises amorphous chromium carbide. The nuclear reactor component provides for improved resistance to oxidation, hydriding, and/or migration of undesired material.
046997504	summary	BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to fuel assemblies for nuclear reactors and, more particularly, is concerned with an apparatus for storage, retrieval and deployment of vertically suspended drag gages used in a semi-automated system for inspecting a fuel assembly for potential control rod guide thimble misalignment. 2. Description of the Prior Art In a typical nuclear reactor, the reactor core includes a large number of fuel assemblies each of which is composed of top and bottom nozzles with a plurality of elongated transversely spaced guide thimbles extending longitudinally between the nozzles and a plurality of transverse support grids axially spaced along and attached to the guide thimbles. Also, each fuel assembly is composed of a plurality of elongated fuel elements or rods transversely spaced apart from one another and from the guide thimbles and supported by the transverse grids between the top and bottom nozzles. The fuel rods each contain fissile material and are grouped together in an array which is organized so as to provide a neutron flux in the core sufficient to support a high rate of nuclear fission and thus the release of a large amount of energy in the form of heat. A liquid coolant is pumped upwardly through the core in order to extract some of the heat generated in the core for the production of useful work. Since the rate of heat generation in the reactor core is proportional to the nuclear fission rate, and this, in turn, is determined by the neutron flux in the core, control of heat generation at reactor start-up, during its operation and at shutdown is achieved by varying the neutron flux. Generally, this is done by absorbing excess neutrons using control rods which contain neutron absorbing material. The guide thimbles, in addition to being structural elements of the fuel assembly, also provide channels or guides for insertion of the neutron absorber control rods within the reactor core. The level of neutron flux and thus the heat output of the core is normally regulated by the movement of the control rods into and from the guide thimbles. In addition to accommodating normal stepped insertion of the control rods, the guide thimbles must allow their rapid insertion should a reactor trip arise. Therefore, one procedure typically carried out to determine the quality of a fuel assembly is an inspection for potential control rod hang up or malfunction by performance of a drag check utilizing tooling rods. The slender tooling rods, referred to collectively as a drag gage, are lowered into the hollow control rod guide thimbles in a vertical attitude. The descending gage must not encounter a drag which results in a weight reduction of fifteen pounds or more to qualify the fuel assembly as acceptable. Heretofore, this inspection task has required use of the main bridge crane and three persons to carry it out. Particularly, in addition to a person to operate the inspection equipment, the inspection procedure has utilized the main bridge crane with the assistance of a crane operator and a hook-up man stationed on an elevating lift platform. Thus, the current inspection task is labor intensive and occupies the crane for prolonged periods of time. Consequently, a need has emerged to improve and automate the manner in which the inspection is carried out. SUMMARY OF THE INVENTION The present invention provides an apparatus designed to satisfy the aforementioned needs by facilitating automated storage, retrieval and deployment of the vertically suspended drag gages used in inspection of the fuel assembly guide thimbles. The general virtues of the apparatus include the modernization of the current drag check facility to achieve productivity and quality gains by the mechanization and automation of most test procedures. Specifically, the employment of a dedicated system eliminates the necessity to use the main bridge crane and thus the requirement for the services of a craneman and hook-up man. Other benefits derived are reduced cycle time, improved safety of personnel and product, and automated sensing of a specified drag effect. The apparatus employs a gripper mechanism on overhead handling and lifting equipment which has associated with it a cylindrical safety device which prevents inadvertent release of the gripper mechanism. The safety device being, passive and automatic in function, does not complicate the normal operation of the gripper mechanism. The apparatus also incorporates an indexable dispenser for the drag gages of the system. Uniquely, the dispenser is mounted in an unorthodox place, such being about the vertical support column of the overhead handling and lifting equipment. Orthodox practice would dictate that a more complicated and costly stand-alone mounting structure be provided to store the drag gages. Thus, the apparatus of the present invention advantageously utilizes space efficiently by incorporating the dispenser about the support column, such as the column of a Jib crane, is less costly than a stand-alone structure, simplifies operation of the apparatus by limiting the distance that must be traveled to retrieve and return the gage, and enhances safety by reducing the area vulnerable to handling/transport problems. Accordingly, the present invention is set forth in a system for inspecting fuel assembly guide thimbles and is directed to an apparatus for handling at least one drag gage being insertable within the guide thimbles. The apparatus comprises: (a) storing means for holding at least one drag gage in a storage position; (b) indexing means for moving the drag gage along a path to dispose the gage at a retrieval-and-return station; (c) loading means operable for respectively gripping and releasing the gage at the retrieval-and-return station; (d) transporting means movable between a work station and a storage station; and (e) hoisting means supporting the loading means and being supported by the transporting means. The hoisting means is operable for respectively raising ad lowering the loading means and the drag gage therewith away from and toward the retrieval-and-return station when the transporting means is at the storage station and operable for respectively raising and lowering the loading means and the gage therewith away from and toward the fuel assembly guide thimbles when the transporting means is at the work station. More particularly, the storing means holds a plurality of drag gages in a series of positions being angularly displaced for one another about a common axis. The indexing means is operable to move the drag gages about an endless path to dispose a selected one of the gages at the retrieval-and-return station. Also, the present invention provides safety means for restraining the loading means in gripping relation with the drag gage. In addition, means is provided for releasing the safety means from restraining the loading means in gripping relation with the drag gage only when disposed at the retrieval-and-return station.
	abstract	A radiation detector, a method of manufacturing a radiation detector, and a lithographic apparatus comprising a radiation detector. The radiation detector has a radiation sensitive surface. The radiation sensitive surface is sensitive to radiation wavelengths between 10-200 nm and charged particles. The radiation detector has a silicon substrate, a dopant layer, a first electrode, and a second electrode. The silicon substrate is provided in a surface area at a first surface side with doping profile of a certain conduction type. The dopant layer is provided on the first surface side of the silicon substrate. The dopant layer has a first layer of dopant material and a second layer. The second layer is a diffusion layer in contact with the surface area at the first surface side of the silicon substrate. The first electrode is connected to dopant layer. The second electrode is connected to the silicon substrate.
	claims	1. A closure apparatus for an overflow opening disposed in a wall of a nuclear engineering plant, the nuclear engineering plant containing a containment including an interior and the wall dividing the interior into a plant space having a reactor pressure vessel and a primary cooling circuit and into an operating space being walkable during normal operation, the closure apparatus comprising:a closure element containing a bursting element, said closure element spring-loaded in a closed state; andan actuating apparatus acting, in a case of a temperature-dependent triggering, directly on said bursting element and resulting in a tearing of said bursting element, and automatically releases a flow cross section when a predetermined trigger temperature on a side of a surrounding area is reached, and said bursting element is configured such that said bursting element tears if said actuating apparatus has not yet been triggered, if a predetermined pressure difference between the plant space and the operating space is present. 2. The closure apparatus according to claim 1, wherein said actuating apparatus is a spring-driven actuating apparatus. 3. The closure apparatus according to claim 1, further comprising a locking apparatus which blocks said actuating apparatus before the predetermined trigger temperature is reached or compensates for it in terms of its effect. 4. The closure apparatus according to claim 1, wherein said bursting element is selected from the group consisting of a bursting film and a bursting screen. 5. The closure apparatus according to claim 1, wherein said closure element is configured and mounted on the wall such that a process of opening is driven or assisted by an inherent weight of said closure element. 6. A closure apparatus for an overflow opening disposed in a wall of a nuclear engineering plant, the nuclear engineering plant containing a containment including an interior and the wall dividing the interior into a plant space having a reactor pressure vessel and a primary cooling circuit and into an operating space being walkable during normal operation, the closure apparatus comprising:a closure element containing a bursting element, said closure element actively held in a closed state by an electromotor force; andan actuating apparatus acting, in a case of a temperature-dependent triggering, directly on said bursting element and resulting in a tearing of said bursting element, and automatically releases a flow cross section when a predetermined trigger temperature on a side of a surrounding area is reached, and said bursting element is configured such that said bursting element tears if said actuating apparatus has not yet been triggered, if a predetermined pressure difference between the plant space and the operating space is present. 7. The closure apparatus according to claim 6, further comprising one of a louver flap and a rotary pendulum flap with a spring return actuator for use in lower ones of the overflow openings of the nuclear engineering plant. 8. A closure apparatus for an overflow opening disposed in a wall of a nuclear engineering plant, the nuclear engineering plant containing a containment containing an interior and the wall dividing the interior into a plant space having a reactor pressure vessel and a primary cooling circuit and into an operating space being walkable during normal operation, the closure apparatus comprising:a locking element;a temperature-dependent trigger apparatus; anda closure element including:a frame element mounted for one of rotating and pivoting on the wall in front of the overflow opening; anda bursting element one of mounted on and clamped in said frame element, said frame element being fixed in a closed position over the overflow opening by said locking element and said locking element being coupled to said temperature-dependent trigger apparatus, such that said locking element is unlocked when a trigger temperature is reached. 9. The closure apparatus according to claim 8, further comprising a remote-controlled apparatus selected from the group consisting of a mechanical remote-controlled apparatus and a pneumatic remote-controlled apparatus; andwherein said temperature-dependent trigger apparatus is disposed remote from said closure element and acts in a trigger event via said remote-controlled apparatus on one of said closure element and said locking element. 10. The closure apparatus according to claim 8, wherein one of said locking element and said temperature-dependent trigger apparatus contains one of a fusible solder and a fusible bead. 11. The closure apparatus according to claim 8, wherein said closure element is configured and mounted on the wall such that a process of opening is driven or assisted by an inherent weight of said closure element. 12. The closure apparatus according to claim 8, wherein said closure element is spring-loaded in a closed state. 13. The closure apparatus according to claim 8, wherein said closure element is actively held in a closed state by an electromotor force. 14. The closure apparatus according to claim 13, further comprising one of a louver flap and a rotary pendulum flap with a spring return actuator for use in a lower one of the overflow openings of the nuclear engineering plant. 15. The closure apparatus according to claim 8, wherein said bursting element is selected from the group consisting of a bursting film and a bursting screen. 16. The closure apparatus according to claim 9, wherein said temperature-dependent trigger apparatus is selected from the group consisting of a temperature-sensitive trigger apparatus and a concentration-sensitive trigger apparatus.
	abstract	The present invention relates to X-ray differential phase-contrast imaging, in particular to a deflection device for X-ray differential phase-contrast imaging. In order to provide differential phase-contrast imaging with improved dose efficiency, a deflection device (28) for X-ray differential phase-contrast imaging is provided, comprising a deflection structure (41) with a first plurality (44) of first areas (46), and a second plurality (48) of second areas (50). The first areas are provided to change the phase and/or amplitude of an X-ray radiation; and wherein the second areas are X-ray transparent. The first and second areas are arranged periodically such that, in the cross section, the deflection structure is provided with a profile arranged such that the second areas are provided in form of groove-like recesses (54) formed between first areas provided as projections (56). The adjacent projections form respective side surfaces (58) partly enclosing the respective recess arranged in between. The side surfaces of each recess have a varying distance (60) across the depth (62) of the recess.
	claims	1. A nuclear fission reactor comprising:a burning wavefront heat generating region of a nuclear fission reactor, the burning wavefront heat generating region including a nuclear fission igniter centrally located within a nuclear fission reactor core and configured to initiate a propagating nuclear fission deflagration wave;a condensed phase density fluid flowable in thermal contact with the burning wavefront heat generating region and with a heat extraction region substantially out of thermal contact with the burning wavefront heat generating region;one or more operating condition detectors positioned to detect an operating condition in the burning wavefront heat generating region of the nuclear fission reactor core and to generate a control signal indicating the detected operating condition;a plurality of neutron modifying structures configured to direct the propagating nuclear fission deflagration wave within the burning wavefront heat generating region of the nuclear fission reactor core according to a selected propagation parameter, the control signal selectively controlling placement of the neutron modifying structures within the burning wavefront heat generating region of the nuclear fission reactor core when the detected operating condition satisfies a predetermined criterion,wherein the selected propagation parameter is a selected propagation rate and the plurality of neutron modifying structures are configured to speed up a propagation rate by being inserted behind a burnfront of the propagating nuclear fission deflagration wave. 2. The nuclear fission reactor of claim 1, wherein the condensed phase density fluid includes at least one condensed phase density fluid chosen from liquid metals, terphenyls, polyphenyls, fluorocarbons, and FLIBE. 3. The nuclear fission reactor of claim 1, wherein the condensed phase density fluid includes a nuclear inert material. 4. The nuclear fission reactor of claim 3, wherein the nuclear inert material includes He4. 5. The nuclear fission reactor of claim 1, wherein the neutron modifying structures include at least one of neutron absorbing material and neutron moderating material. 6. The nuclear fission reactor of claim 1, wherein the plurality of neutron modifying structures are further configured to direct the propagating nuclear fission deflagration wave within the burning wavefront heat generating region of the nuclear fission reactor core by selected ones of the neutron modifying structures being inserted into and removed from the burning wavefront heat generating region. 7. The nuclear fission reactor of claim 1, wherein the detected operating condition includes at least one local temperature in the nuclear fission reactor core, wherein the one or more operating condition detectors include a plurality of temperature detectors positioned to detect local temperature in the nuclear fission reactor core, and wherein the control signal includes a temperature profile of the nuclear fission reactor core. 8. The nuclear fission reactor of claim 1, wherein the detected operating condition includes at least one local temperature in the nuclear fission reactor core, wherein the one or more operating condition detectors include a plurality of temperature detectors positioned to detect local temperature in the nuclear fission reactor core, wherein the control signal includes a temperature profile of the nuclear fission reactor core, and wherein the plurality of neutron modifying structures are selectively removed from the nuclear fission reactor core when the at least one local temperature is below a predetermined temperature threshold. 9. The nuclear fission reactor of claim 1, wherein the control signal indicates at least one member of a group comprising: a power level, neutron level, neutron spectrum, neutron absorption, and fuel burnup level. 10. A nuclear fission reactor comprising:a burning wavefront heat generating region of a nuclear fission reactor, the burning wavefront heat generating region including a nuclear fission igniter centrally located within a nuclear fission reactor core and configured to initiate a propagating nuclear fission deflagration wave;a condensed phase density fluid flowable in thermal contact with the burning wavefront heat generating region and with a heat extraction region substantially out of thermal contact with the burning wavefront heat generating region;one or more operating condition detectors positioned to detect an operating condition in the burning wavefront heat generating region of the nuclear fission reactor core and to generate a control signal indicating the detected operating condition;a plurality of neutron modifying structures configured to direct the propagating nuclear fission deflagration wave within the burning wavefront heat generating region of the nuclear fission reactor core according to a selected propagation parameter, the control signal selectively controlling placement of the neutron modifying structures within the burning wavefront heat generating region of the nuclear fission reactor core when the detected operating condition satisfies a predetermined criterion,wherein the selected propagation parameter is a selected propagation rate and the plurality of neutron modifying structures are configured to slow down a propagation rate by being inserted ahead of a burnfront of the propagating nuclear fission deflagration wave. 11. The nuclear fission reactor of claim 10, wherein the condensed phase density fluid includes at least one condensed phase density fluid chosen from liquid metals, terphenyls, polyphenyls, fluorocarbons, and FLIBE. 12. The nuclear fission reactor of claim 10, wherein the condensed phase density fluid includes a nuclear inert material. 13. The nuclear fission reactor of claim 12, wherein the nuclear inert material includes He4. 14. The nuclear fission reactor of claim 10, wherein the neutron modifying structures include at least one of neutron absorbing material and neutron moderating material. 15. The nuclear fission reactor of claim 10, wherein the plurality of neutron modifying structures are further configured to direct the propagating nuclear fission deflagration wave within the burning wavefront heat generating region of the nuclear fission reactor core by inserting and removing selected ones of the neutron modifying structures into the burning wavefront heat generating region. 16. The nuclear fission reactor of claim 10, wherein the detected operating condition includes at least one local temperature in the nuclear fission reactor core, wherein the one or more operating condition detectors include a plurality of temperature detectors positioned to detect local temperature in the nuclear fission reactor core, and wherein the control signal includes a temperature profile of the nuclear fission reactor core. 17. The nuclear fission reactor of claim 10, wherein the detected operating condition includes at least one local temperature in the nuclear fission reactor core, wherein the one or more operating condition detectors include a plurality of temperature detectors positioned to detect local temperature in the nuclear fission reactor core, wherein the control signal includes a temperature profile of the nuclear fission reactor core, and wherein the plurality of neutron modifying structures are selectively removed from the nuclear fission reactor core when the at least one local temperature is below a predetermined temperature threshold. 18. The nuclear fission reactor of claim 10, wherein the control signal indicates at least one member of a group comprising: a power level, neutron level, neutron spectrum, neutron absorption, and fuel burnup level.
	abstract	The present invention relates to a sintered nuclear fuel pellet wherein one or more consolidated bodies of a burnable absorber are inserted inside, wherein the one or more consolidated bodies of the burnable absorber do not include nuclear fuel which includes UO2, and the one or more consolidated bodies of the burnable absorber are inserted into a radially central region of the sintered nuclear fuel pellet, such that the one or more consolidated bodies are surrounded by the nuclear fuel pellet without being exposed to an outside of the sintered nuclear fuel pellet. The present invention can optimize the regulation of excess reactivity by optimizing the self-shielding and the burning speed of the burnable absorber using one or more consolidated bodies the burnable absorber.
055286593	abstract	The invention provides a polarizing device and a method for producing and utilizing the device. The device produces a modification in radiation flux and provides a bias toward photons approaching a target's face at more or less right angles. Accordingly, the radiation flux polarizing device reduces the number of photons that are not traveling at near right angle to the face of a "target" being irradiated, without significantly reducing photons approaching, or reaching the minimum base point in the target. In a sense, the invention converts a normal isotropic radiation source to one that is anisotropic.
	summary
	summary
	abstract	An external reactor vessel cooling and electric power generation system according to the present invention includes an external reactor vessel cooling section formed to enclose at least part of a reactor vessel with small-scale facilities so as to cool heat discharged from the reactor vessel, a power production section including a small turbine and a small generator to generate electric energy using a fluid that receives heat from the external reactor vessel cooling section, a condensation heat exchange section 140 to perform a heat exchange of the fluid discharged after operating the small turbine, and condense the fluid to generate condensed water, and a condensed water storage section to collect therein the condensed water generated in the condensation heat exchange section, wherein the fluid is phase-changed into gas by the heat received from the reactor vessel. The external reactor vessel cooling and electric power generation system according to the present invention can continuously operate even during an accident as well as during a normal operation to cool the reactor vessel and produce emergency power, thereby enhancing system reliability. The external reactor vessel cooling and electric power generation system according to the present invention can easily apply safety class or seismic design using small-scale facilities, and its reliability can be improved owing to applying the safety class or seismic design.
	abstract	Scanning probe apparatus, including a tip-electrode which is coupled to be held at a substantially ground potential, a counter-electrode which is positioned in proximity to the tip-electrode, a voltage source, coupled to maintain the counter-electrode at a non-ground potential, and positioning-instrumentation, which is adapted to maintain the tip-electrode at a suitable position relative to a surface of a ferroelectric sample located in a space between the tip-electrode and the counter-electrode. The apparatus generates an electric field in the ferroelectric sample greater than a coercive field of the sample.
	summary
	abstract	A method and apparatus for aligning a laser beam coincident with a charged particle beam. The invention described provides a method for aligning the laser beam through the center of an objective lens and ultimately targeting the eucentric point of a multi-beam system. The apparatus takes advantage of components of the laser beam alignment system being positioned within and outside of the vacuum chamber of the charged particle system.
	abstract	Disclosed is a system for separating and coupling a top nozzle of a nuclear fuel assembly. There is provided a lock insert configured to support the top nozzle of the nuclear fuel assembly by being coupled to a guide hole provided in a flow channel plate of the top nozzle, the lock insert including: a body in a hollow shape; and an insertion part provided on a top portion of the body and inserted into the guide hole, wherein a circumference of the insertion part is variable in size, thereby being capable of being inserted into the guide hole. Accordingly, disassembly and reassembly of the top nozzle of the nuclear fuel assembly and the lock insert are simplified, thereby simplifying and reducing the number of processes involved therein. Accordingly, the system is effective for maintenance and repair of the nuclear fuel assembly.
	summary
	summary
	description	This application claims priority to the following provisional patent application, the entirety of which is expressly incorporated herein by reference: U.S. Ser. No. 60/891,277 filed on Feb. 23, 2007, entitled “Methods And Systems For The Focusing, Directing and Energy Filtering of X-Rays For Non-Intrusive Inspection”. 1. Field of the Invention This patent application relates to systems and methods for the directing and energy filtering of X-ray beams via diffraction and reflection using crystals (including Laue and Bragg diffraction). Embodiments in the field of non-intrusive inspection technology are presented. The capability to direct and energy filter X-ray beams greatly expands existing and potential applications of X-ray based inspection technologies. The term X-ray is used to denote penetrating electromagnetic radiation and it is interchangeable with other traditional characterizations that use terms such as photons, gamma-rays, etc. when referring to electromagnetic radiation in the X-ray energy range. 2. Background Information There are a variety of inspection regimes where the use of a directed or energy filtered X-ray beam may be highly advantageous. A common method for producing a high intensity X-ray source in the photon energy range greater than 100 keV is electron bremsstrahlung. However, the bremsstrahlung process produces a continuous energy distribution of photons that are only weakly forward peaked for electron beam energies under consideration in non-intrusive inspection. The ability to direct this beam to a distant point may increase the distance over which inspections are practical by overcoming the divergence of the X-ray beam between the location of its production and the target, and the ability to energy filter may be advantageous in reducing the energy distribution of the incident photons. Similarly, X-rays scattered from a target will fall off in intensity as the distance between the target and a detector is increased. A method of capturing these X-rays and imaging them onto a small detector may be very advantageous, in particular when the detectors require high photon energy-resolution and are very expensive. The result may be an increase in the distance over which such a system can operate, an increase in detection signal, reduced noise, and reduced cost. There are coherent, nearly mono-energetic sources of X-rays in which the divergence and size of the beam is very small. These coherent sources of X-rays may be very useful for remote inspection since their size even at tens of meters may only be a few centimeters in diameter. However, the ability to inspect large objects (of order a meter or greater) may require some method to scan the beam over the target. An efficient mechanism for directing such a coherent nearly mono-energetic X-ray beam would be desirable. Techniques for implementing inspection regimes are discussed in U.S. Pat. No. 5,115,459, Explosives Detection Using Resonance Fluorescence of Bremsstrahlung Radiation, U.S. Pat. No. 5,420,905, Detection of Explosives and Other Materials Using Resonance Fluorescence, Resonance Absorption, and Other Electromagnetic Processes with Bremsstrahlung Radiation, U.S. Pat. No. 7,120,226, Adaptive Scanning Of Materials Using Nuclear Resonance Fluorescence Imaging, U.S. Patent Publication No. 2006/0188060A1, Use of Nearly Monochromatic and Tunable Photon Sources with Nuclear Resonance Fluorescence in Non-intrusive Inspection of Containers for Material Detection and Imaging, U.S. Patent Publication No. 2007/0145973A1, Methods And Systems For Active Non-Intrusive Inspection And Verification Of Cargo And Goods, and U.S. Pat. No. 7,286,638, Methods and Systems for Determining the Average Atomic Number and Mass of Materials, the contents of each of which are incorporated herein by reference. We have developed systems and methods using crystal diffraction and reflection (including Laue and Bragg diffraction) for the directing and energy filtering of X-ray beams used in inspection systems. This may have the effect of increasing the efficiency and performance of inspection systems. Examples of how the use of diffraction from crystals can direct or energy filter X-ray sources are summarized below. The redirection of an X-ray beam can achieve an approximate focal point. This reduces the 1/r2 dependence of the intensity of the X-rays on distance from a source or scatterer and increases the sensitivity of measurements particularly for remote target inspection. The beam may be directed in a desired direction. For example, this can be used as a method for scanning the X-ray beam across a volume of interest. Crystal diffraction and reflection can also be used to energy filter an X-ray beam with a wider energy distribution than desirable. This can be used to select a particular energy or energy range for inspection or to remove unwanted regions of the energy spectrum. This filtering may aid in reducing both the dose delivered to the inspection volume and the background from incident photons that do not contribute to the signal associated with the inspection method. Unless otherwise specified, the illustrated embodiments can be understood as providing exemplary features of varying detail of certain embodiments, and therefore, unless otherwise specified, features, components, modules, and/or aspects of the illustrations can be otherwise combined, specified, interchanged, and/or rearranged without departing from the disclosed devices or methods. Additionally, the shapes and sizes of components are also exemplary, and unless otherwise specified, can be altered without affecting the disclosed devices or methods. As shown in FIG. 1A, a crystal deflects photons of a specific energy incident on its surface at a particular angle via Bragg diffraction. The incident angle at which Bragg diffraction will occur, and the resulting angle of reflection, depend upon the crystal spacing and the incident photon energy according to principles that will be well understood by a person of skill in the art. In particular,2d Sin θ=nλ,whered is the crystal spacing,θ is the angle of incidence and reflection,λ is the photon wavelength andn is the order of the diffraction maximum. Thus, for any given energy and crystal a specific angle of incidence determined by the above formula will lead to a reflected beam at an angle equal to the angle of incidence. (In FIG. 1A, A denotes the width of the incident or exiting beam.) As shown in FIG. 1B, a crystal also deflects photons of specific energy that enter it through its surface at a particular angle via Laue diffraction. Again, the incident angle and the angle of outgoing deflection θ depend upon the crystal spacing and the incident photon energy according to principles that will be well understood by a person of skill in the art. As with Bragg diffraction, for each energy there will be maxima at certain transmitted angles, depending on the crystal spacing and orientation. Because crystals may have different spacings in different planes, the possible angles may vary with the crystal orientation. (In FIG. 1B, A again denotes the width of the incident or exiting beam.) Directing of X-Ray Beams An efficient mechanism for directing a coherent mono-energetic X-ray beam is to “steer” it using crystal diffraction, which may be either Laue or Bragg diffraction. The diffraction could be used to scan a beam across a target, or to increase detection sensitivity. A system of crystals could be used to irradiate a target or collect radiation from a target onto a detector. Embodiments of these principles are described hereinbelow, but we will first present an embodiment that takes advantage of Laue diffraction to enhance the available photon beam in a desired energy range by selectively directing photons in that energy range. In FIG. 2, Laue diffraction is used to select X-rays in a particular energy range to be directed onto a target. A divergent beam of X-rays 201 with multiple energy components is incident on a crystal lens 202 composed of a plurality of crystal surfaces arranged in concentric circles. For clarity the lens is shown rotated from its actual orientation in FIG. 2. (For example, as deployed the beam 201 is incident on the plane containing the crystal surfaces arranged in concentric circles, such that the central axis of the beam is substantially perpendicular to the plane containing the crystal lens.) Through the appropriate choice of the crystal structures and their arrangement, according to principles known to those of skill in the art, this lens will select and direct a specific X-ray energy range with high efficiency. In particular, depending on the desired energy, and the crystal chosen, each crystal surface in a given concentric circle may be oriented at an appropriate angle such that photons of the desired energy range are incident on each crystal surface at a desired angle and are deflected in the desired direction. This energy-filtered beam can be used to interrogate a small region of a target 203. This technique increases the signal to noise ratio by focusing the beam on a smaller cross section while simultaneously reducing the background from other photons that do not contribute to the production of signal. Crystals to be used for this application (and the other applications described herein) may be made from a variety of materials that will be known to a person of skill in the art, including in particular copper, carbon, silicon and germanium. In typical applications, the crystals will be on the order of 1 cm. thick and may be several cm. across. In general, crystals with small atomic spacing are effective in providing useful deflections at the energies of interest for target inspection using the approaches laid out in the patents and patent applications incorporated herein. In addition, materials with high electron density also are desirable, especially for higher energies. Gold and silver are excellent candidates as crystal materials. A nearly monochromatic photon beam is often produced with a high degree of directionality due to the intrinsic processes used to produce the beam. Practical sources of nearly monochromatic photon beams are made possible by techniques such as laser backscattering from energetic electrons (among others). Such beams are well suited for example, for scanning of containers using Nuclear Resonance Fluorescence, in part because of the lower X-ray dose that is possible during an inspection of a container since the photon beam is concentrated in narrow regions of the energy spectrum. This is in contrast to a bremsstrahlung beam, which has photons at all energies below the end-point energy of the electron beam that produces it. One characteristic of the photon beams that result from laser backscattering is a photon beam that may be only a few centimeters in diameter at a distance of 30 meters (for one example) from the photon source. The direction of the photons is also a fixed parameter for each electron beam energy and laser photon energy. While these characteristics are very desirable in many situations, they represent a problem for scanning a container that may be many meters long and wide. Scanning the beam over the surface of a container generally is impractical if the directions of both the laser beam and electron beam are to be changed to accommodate each photon direction. Crystal diffraction presents a method for such inspection because of its efficient deflection of a photon beam through an angle. For example, a crystal of a material such as copper (as one example) can deflect the photon beam through an angle such that a deflection of a meter is possible at a practical distance of tens of meters. By moving the crystal so as to change the angle of the crystalline planes relative to the beam axis, the photon deflection angle may be changed and thus the position of the beam on the target (container under inspection) may be moved. In addition, by suitably rotating the crystal so as to maintain the same incident angle, the direction of beam deflection may be changed. Thus, the photon beam may be scanned over the surface of a target that is many times the size of the beam spot. Crystals may have uniform structures and may be curved by thermal or mechanical means to provide focusing or defocusing as desired by the specific application. A suitable crystal can be used to scan the photon beam across a region of interest by Bragg diffraction. In FIG. 3A, the specific direction of the scattered beam 303 is determined by the crystal spacing and the angle of crystal lens 301 that deflects the incident beam 302. (The incident angle should be chosen to represent a maximum of Bragg diffraction for the chosen crystal spacing and orientation and the desired photon energy.) Mechanical motion of the lens 301 may be provided and controlled for positioning the lens 301 in continuous or step-wise motion. The motion may be rotary motion about an axis 306 to produce a range of possible lens positions shown for example as lens 301 and lens 301a. The lens may be rotated by a lens rotator 308. In particular, if the rotation is about an axis 306 that is along the incident beam direction 302, then as the crystal is rotated the incident angle will be constant, and Bragg scattering will continue at the maximum. Thus, depending on the controlled angular position of the lens 301 the scattered beam may follow the path indicated by scattered beam 303a or the path indicated by scattered beam 303, and/or may be scanned along a path between that of scattered beam 303 and scattered beam 303a and may be incident on target 305 at target region 304a or target region 304 (or at regions of the target 305 between target region 304 and target region 304a). (FIG. 3A only shows the beam deflection as a projection in the plane of the diagram, but there is also a component of deflection out of the diagram plane as the crystal lens 301, 301a rotates. See also the discussion hereinbelow of FIG. 4.) A series of lenses may be used, as illustrated in FIG. 3C. Although a scan along an arc was illustrated in FIG. 3A, it will be understood by those skilled in the arts that by using two scanning lenses 301, 310 in series, suitably oriented at an angle with respect to one another, and suitably positioned with respect to the incident beam 302, as shown in FIG. 3C, a two-dimensional scan pattern can optionally be produced by the scattered beam 303 at the target 305. As illustrated, scattered beam 303 is incident upon target region 304, but other target regions can be illuminated by suitably rotating the lens 310 with the lens rotator 308, and/or moving the target 305 with the target mover 309. Alternatively, it will be understood by those skilled in the arts, that by using multiple lenses oriented at specific angles with respect to the beam, and suitably moving one or another into the beam, different incident angles and therefore different energies may be selected for the system. The motion of the crystal may be achieved by a variety of mechanical methods, or alternatively by other methods, for examples, piezoelectric, thermal, or sonic methods. In order to scan a target with a cross-sectional area, the target 305 may be moved as the crystal is rotated, for example by using target mover 309, so that the arc of the circle over which the beam is deflected is swept over the surface of the target. In addition, other arcs may be scanned across the target by suitable choice of other order reflection maxima (different values of n). Motion of the target can be stopped and the lens positioned so as to pay further attention to an area where scanning results indicate further investigation is appropriate. Rather than using Bragg refraction from a crystal surface, as illustrated in FIG. 3A, a Laue lens may be used for the same purpose, as shown in FIG. 3B. In this configuration the specific direction of the scattered beam 313 is determined by the crystal spacing and the angle of lens 311 that deflects the incident beam 312. (The incident angle should be chosen to represent a maximum of Laue diffraction for the chosen crystal spacing and orientation and the desired photon energy.) Mechanical motion of the lens 311 may be provided and controlled for positioning the lens 311 in continuous or step-wise motion. The motion may be rotary motion about an axis 316 to produce a range of possible lens positions shown for example as lens 311 and lens 311a. The lens may be rotated by a lens rotator 318. In particular, if the rotation is about an axis 316 that is along the incident beam direction 312, then as the crystal is rotated the incident angle will be constant, and Bragg scattering will continue at the maximum. Thus, depending on the controlled angular position of the lens 311 the scattered beam may follow the path indicated by scattered beam 313a or the path indicated by scattered beam 313, and/or may be scanned along a path between that of scattered beam 313 and scattered beam 313a and may be incident on target 315 at target region 314a or target region 314 (or at regions of the target 315 between target region 314 and target region 314a). (FIG. 3A only shows the beam deflection as a projection in the plane of the diagram, but there is also a component of deflection out of the diagram plane as the crystal lens 311, 311a rotates. See also the discussion hereinbelow of FIG. 4.) A series of lenses may be used. Although a scan along an arc is illustrated in FIG. 3B, it will be understood by those skilled in the arts that by using two scanning lenses in series, suitably oriented at an angle with respect to one another, and suitably positioned, a two-dimensional scan pattern can optionally be produced at the target 315. Alternatively, it will be understood by those skilled in the arts, that by using multiple lenses oriented at specific angles with respect to the beam, and suitably moving one or another into the beam, different incident angles and therefore different energies may be selected for the system. The motion of the crystal may be achieved by a variety of mechanical methods, or alternatively by other methods, for examples, piezoelectric, thermal, or sonic methods. In order to scan a target with a cross-sectional area, the target 315 may be moved as the crystal is rotated, for example by using target mover 319, so that the arc of the circle over which the beam is deflected is swept over the surface of the target. In addition, other arcs may be scanned across the target by suitable choice of other order reflection maxima (different values of n). Motion of the target can be stopped and the lens positioned so as to pay further attention to an area where scanning results indicate further investigation is appropriate. Another illustration of a similar embodiment for scanning a photon beam is shown in FIG. 4. The diffracting crystal 402 is rotated about an axis 403 that is coincident with the photon beam 401, maintaining the orientation of the beam and its crystalline planes at the same angle. The scattered beam 404 follows a conical scanning pattern around the beam axis and traces out a cone that projects on the container target being scanned as a circle 405 (or an arc thereof, depending on the container size) in the case of a container whose face is perpendicular to the incident beam axis. The dimensions of the scanned line on the target face depend on the angle of the deflected beam and the distance to the object scanned. This dependence is given by standard geometrical considerations. For clarity, the path 405 of the scattered beam 404 is shown rotated from its actual configuration in FIG. 4. For example, it will be understood that if the crystal 402 is rotated about an axis parallel to and coincident with the incident beam 401, the path 405 will (if the target has a face perpendicular to the incident beam 401) trace out a circle in a plane perpendicular to the incident beam. Although Laue diffraction is illustrated in FIG. 4, it will be understood that Bragg diffraction also may be used in suitable geometries. X-Ray Energy Filtering An application of crystal diffraction using a Laue lens is the energy filtering of an X-ray beam. For example, a Laue crystal can be used to select and focus an energy region (or multiple energy regions) from a continuous X-ray beam produced by electron bremsstrahlung or other methods that produce a beam with a broad energy spectrum. This can both reduce the background from interactions of photons in the beam that do not contribute to the “signal” and reduce the dose delivered to the inspection volume. In this case, the Laue lens acts as a narrow-band energy filter. This principle can also be used to create high or low pass filters, which filter photons above or below an energy threshold. The use of a bremstrahlung photon beam, or other photon beam produced by a method that provides a broad energy spectrum, for interrogation of cargo has the possible disadvantage of having photons in an energy range that are not of interest. These photons do not contribute to the signal that is being measured, and may deposit unnecessary dose to the container that is being scanned. Similarly, radiation scattered from a target may have energy regions that are not utilized in the inspection technique. A Laue lens, which scatters photons of different energies through different angles, can be used as a filter for the broad spectrum of photons. The process can also be used to make a set of diverging photons more collimated. In FIGS. 5A, 5B and 5C a multi energy photon beam 501, 506, 520 is incident on a Laue lens 502, 507, 522. For clarity the lens is shown rotated from its actual orientation in FIGS. 5A, 5B and 5C. (For example, as deployed the beams 501 and 520 in FIGS. 5A and 5C are incident on the plane containing the crystal surfaces arranged in concentric circles, such that the central axis of the beam is substantially perpendicular to the plane containing the crystal lens. In FIG. 5B, the beam 506 is incident on the plane containing the crystal surfaces arranged in rows, such that the plane of the beam is substantially perpendicular to the plane containing the lens.) Depending on the desired energy range, and the crystal chosen, each crystal surface in a given concentric circle (or, for FIG. 5B, in a given row) may be oriented at an appropriate angle such that photons of the desired energy range are incident on each crystal surface at a desired angle and are deflected in the desired direction. The lens deflects lower energy photons 503, 508, 524 more strongly than higher energy photons 504, 510, 526. In FIG. 5A, cylindrical symmetry is shown and the low energy photons 503 are focused to the center of the beam where they are absorbed (for example, by a high-Z material such as lead) in absorber 505. In FIG. 5B, a planar or fan beam 506 is passed through a Laue lens 507, which deflects the low energy photons 508 so that they are absorbed by absorber 509 while higher energy photons 510 are passed. In FIG. 5C, a cylindrical symmetry is shown again. The lower energy photons 524 are focused to the center of the beam where they are absorbed by absorber 530. The higher energy photons 526 are least focused and are absorbed by high energy absorber 532. The intermediate energy photons 528 are focused an intermediate amount by the lens 522 and are passed, forming a band pass filter for selecting photons having a selected range of energies. In the system of FIG. 5C, by optionally omitting the absorber 530, a low pass filter is formed for selecting photons having an energy lower than a selected energy. Although the configuration in FIG. 5C shows cylindrical symmetry, it will be apparent to those skilled in the art that corresponding band pass and low pass filters can be formed for the planar or fan beam configuration of FIG. 5B by suitable placement of absorbers. The configurations shown in FIGS. 5A and 5C, in addition to performing energy filtering, also are capable of forming a filtered and collimated beam of high energy photons 504 (FIG. 5A) or selected intermediate energy photons 528 (FIG. 5C) as shown. In all of the configurations shown in FIGS. 5A, 5B and 5C, only photons in the desired energy range are passed through the lens/absorber system.
	claims	1. A method for employing patterning process statistics for ground rules waivers and optimization, comprising:applying Optical Proximity Correction (OPC) to alter a ground rules layout using plan of record process methods to improve mask pattern images;simulating images produced by a mask;mapping patterning process variation distributions into an intersect area distribution by creating a histogram based upon a plurality of processes for the intersect area wherein mapping includes accumulating intersect area data for random process points and sorting the intersect area data into different bins, wherein given g and h as probability distribution functions, a ratio of a Monte Carlo sample count over a total sample size is given by g(x)h(y)dxdy, and if an intersect area function is a(x,y), then a distribution function f(z) for the intersect area is: f(z)dz=∫g(x)h(y)dxdy, for z≦a(x,y)≦z+d where, g, h and f are normalized probability distribution functions such that ∫g(x)dx=1 for all x, and ∫h(y)dy=1 for all y, and ∫f(z)dz=1 for all z; andanalyzing the intersect area using the histogram to provide ground rule waivers and optimization. 2. The method as recited in claim 1, wherein simulating images produced by a mask includes simulating images on computer through process lithography models. 3. The method as recited in claim 1, wherein applying OPC to alter a mask pattern using plan of record process methods includes applying lithographic exposure focus and dose distributions. 4. The method as recited in claim 1, wherein mapping patterning process variation distributions into an intersect area distribution includes analyzing the histogram to grant acceptable ground rules waivers and acceptable geometrical changes for a given a set of ground rules. 5. The method as recited in claim 1, further comprising, modifying a ground rules layout based upon the analyzing step. 6. The method as recited in claim 5, further comprising, fabricating a semiconductor chip in accordance with modified ground rules. 7. A computer program product employing patterning process statistics for ground rules waivers and optimization, comprising a computer useable medium including a computer readable program, wherein the computer readable program when executed on a computer causes the computer to:applying Optical Proximity Correction (OPC) to alter a ground rules layout using plan of record process methods to improve mask pattern images;simulating images produced by a mask;mapping patterning process variation distributions into an intersect area distribution by creating a histogram based upon a plurality of processes for the intersect area wherein mapping includes accumulating intersect area data for random process points and sorting the intersect area data into different bins, wherein given g and h as probability distribution functions, a ratio of a Monte Carlo sample count over a total sample size is given by g(x)h(y)dxdy, and if an intersect area function is a(x,y), then a distribution function f(z) for the intersect area is: f(z)dz=∫g(x)h(y)dxdy, for z≦a(x,y)≦z+d where, g, h and f are normalized probability distribution functions such that ∫g(x)dx=1 for all x, and ∫h(y)dy=1 for all y, and ∫f(z)dz=1 for all z; andanalyzing the intersect area using the histogram to provide ground rule waivers and optimization. 8. The computer program product as recited in claim 7, wherein simulating images produced by a mask includes simulating images on computer through process lithography models. 9. The computer program product as recited in claim 7, wherein applying OPC includes applying lithographic exposure focus and dose distributions. 10. The computer program product as recited in claim 7, wherein mapping the patterning process variation distributions into an intersect area distribution by creating a histogram includes analyzing the histogram to grant acceptable ground rules waivers and acceptable geometrical changes for a given a set of ground rules. 11. The computer program product as recited in claim 7, wherein the program further causes the computer to modify a ground rules layout based upon the analyzing step. 12. The computer program product as recited in claim 11, wherein the program further causes the computer to fabricate a semiconductor chip in accordance with modified wound rules. 13. A system employing patterning process statistics for ground rules waivers and optimization, comprising:a processing device configured to apply Optical Proximity Correction (OPC) to alter a ground rules layout to create a mask pattern to which patterning process variation distributions are applied to create, waive and optimize ground rules for semiconductor chip layouts; andan analysis module configured to map the patterning process variation distributions into an intersect area distribution by creating a histogram based upon a plurality of processes for an intersect area and to analyze the intersect area using the histogram to provide ground rule waivers and layout optimization wherein the map includes accumulated intersect area data for random process points and sorts the intersect area data into different bins, wherein given g and h as probability distribution functions, a ratio of a Monte Carlo sample count over a total sample size is given by g(x)h(y)dxdy, and if an intersect area function is a(x,y), then a distribution function f(z) for the intersect area is: f(z)dz=∫g(x)h(y)dxdy, for z≦a(x,y)≦z+d where, g, h and f are normalized probability distribution functions such that ∫g(x)dx=1 for all x, and ∫h(y)dy=1 for all y, and ∫f(z)dz=1 for all z. 14. The system as recited in claim 13, wherein the analysis module includes a software program run on the processing device. 15. The system as recited in claim 13, wherein processing device includes through process lithography models to simulate images produced by a mask. 16. The system as recited in claim 13, wherein the patterning process variation distributions include lithographic exposure focus and dose distributions. 17. The system as recited in claim 13, wherein the analysis module determines ground rules waivers and acceptable geometrical changes for a given a set of ground rules based upon the histogram. 18. The system as recited in claim 13, wherein the analysis module outputs a modified layout according to waived and optimized ground rules. 19. The system as recited in claim 18, wherein the modified layout is employed to fabricate a semiconductor chip. 20. The system as recited in claim 18, wherein an intersect area includes an area of overlap between a pair of layers in a layout.
	description	This application hereby claims priority under 35 U.S.C. §119 to U.S. Provisional Patent Application No. 60/504,116 filed on 18 Sep. 2003, entitled “Motion Artifact Detection and Analysis Tool,” by inventors Eric Boucher and Joseph V. Miseli, and to U.S. Provisional Patent Application No. 60/514,870 filed on 27 Oct. 2003, entitled “Motion Artifact Detection and Analysis Tool,” by inventors Eric Boucher and Joseph V. Miseli. 1. Field of the Invention The present invention relates to video displays. More specifically, the present invention relates to a method and an apparatus for detecting motion-induced artifacts on electronic display systems. 2. Related Art Liquid Crystal Displays (LCDs) have considerably more difficulty than traditional Cathode Ray Tube (CRT) displays in accurately reproducing moving video images. In recent years, LCDs have advanced beyond CRTs in size and resolution, and are becoming comparable to CRTs in visual performance. During this time, visual performance issues, in which the LCDs lag the CRTs, have been addressed and have been improved significantly. However, until recently, the motion performance of LCDs has been considered, but only basic performance with regard to pixel response time and simple motion artifacts has been addressed. In determining the performance of LCD displays, many manufacturers qualify the product to assure that motion on the displays is within good engineering bounds. They may do simple image movement testing or response time testing to quantify it. To date, their assessment techniques and options are quite limited. Until other performance issues were addressed, motion performance issues for LCDs have generally been on the back burner. Now that these other performance issues have been controlled, it is time to deal with motion performance issues in LCDs. Hence, what is needed is a method and an apparatus for testing motion performance in LCDs and other electronic display systems without the limitations listed above. One embodiment of the present invention provides a system that tests the motion performance of an electronic display system, wherein the electronic display system is comprised of a display, graphics processing software, graphics processing circuitry, and an interface coupling the display and the graphics processing circuitry. The system starts by receiving a request to measure an amount of distortion of an object in motion. In response to the request, the system measures the amount of distortion of the object in motion. In a variation on this embodiment, the system displays a second object and measures the distortion that occurs when the two objects interact. In a variation on this embodiment, the system receives a request to change a visual attribute of the object. In response to this request, the system changes the visual attribute of the object. In a further variation, the visual attribute can include color, size, shape, shading, fill pattern, speed, direction of movement, and type of movement. In a variation on this embodiment, measuring the amount of distortion of the object in motion involves placing a ruler on a boundary of the object where the distortion occurs, increasing the width of the ruler until it covers the distortion, and then measuring the width to determine the size of the distortion. In a further variation, the ruler is displayed every nth display cycle to minimize distortion of the ruler. In a further variation, the width of the ruler is used to determine the response time of pixels in the display for any color or gray scale level. In a variation on this embodiment, the distortion can include flickering, flashing, smearing, bluring, line spreading, geometric distortion, color-induced artifacts, and inaccurate color reproduction. In a variation on this embodiment, the system stores the set of test parameters to a storage medium to facilitate producing an identical set of test parameters during a subsequent test. In a variation on this embodiment, the system records the measured distortion on a storage medium. Note that this facilitates in creating a benchmark and a report for a display system under test and provides information for characterizing the display performance over multiple test conditions. The following description is presented to enable any person skilled in the art to make and use the invention, and is provided in the context of a particular application and its requirements. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present invention. Thus, the present invention is not intended to be limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed herein. The data structures and code described in this detailed description are typically stored on a computer readable storage medium, which may be any device or medium that can store code and/or data for use by a computer system. This includes, but is not limited to, magnetic and optical storage devices such as disk drives, magnetic tape, CDs (compact discs) and DVDs (digital versatile discs or digital video discs), and computer instruction signals embodied in a transmission medium (with or without a carrier wave upon which the signals are modulated). For example, the transmission medium may include a communications network, such as the Internet. Display-Testing for Motion Artifacts FIG. 1 illustrates a system for testing displays for motion artifacts in accordance with an embodiment of the present invention. The system illustrated in FIG. 1 comprises server 104 and client 108 which are coupled to network 100. Note that server 104 can generally include any computational node including a mechanism for servicing requests from a client for computational and/or data storage resources. Also, note that client 108 can generally include any node on a network including computational capability and including a mechanism for communicating across the network. Network 100 can generally include any type of wire or wireless communication channel capable of coupling together computing nodes. This includes, but is not limited to, a local area network, a wide area network, or a combination of networks. In one embodiment of the present invention, network 100 includes the Internet. Display 102 is the display that is being tested for motion artifacts. Note that the motion artifacts can be caused by any part of the display system, including graphics processing circuitry, the interface coupling the graphics processing circuitry to the display, and the display itself. Display 102 is coupled to server 104. Also coupled to server 104 is keyboard 105 and mouse 106. During the testing process, observer 112 may use GUI 110 on client 108 to manipulate objects on display 102 to test for motion induced artifacts. Additionally, observer 112 may use keyboard 105 and/or mouse 106 to manipulate objects on display 102. Display-Testing Software FIG. 2 illustrates the structure of display-testing software in accordance with an embodiment of the present invention. In one embodiment of the present invention, this software is known as the Motion Artifact Detection and Analysis Tool (MADAT). In this embodiment, MADAT is installed on server 104, and is comprised of engine 200, as well as various support modules. These modules can include, network interface module 201, timer control module 202, object control module 204, color control module 206, analysis module 208, overlay engine module 210, file manipulation module 212, miscellaneous module 214, and display module 216. Network interface module 201 allows engine 200 to communicate with GUI 110. Note that GUI 110 can exist on any machine coupled to network 100, or even on server 104 itself. Overlay engine module 210 allows two objects to be controlled simultaneously in order to test the interaction of two moving objects. Overlay engine module 210 is comprised of an almost identical set of components as the MADAT software itself. For instance, within overlay engine module 210, you will find a timer control, an object control, and a color control. Display module 216 takes input from timer control module 202, object control module 204, color control module 206 and overlay engine module 210, and uses these inputs to determine a set of graphical images to output to display 102, which is the display under test. GUI—Geometry Configuration FIG. 3 illustrates the geometry configuration portion of GUI 110 in accordance with an embodiment of the present invention. GUI 110 allows observer 112 to set various attributes related to the geometry of the object being used to test display 102. These attributes can include oscillation, angle, line attributes, location, dimensions, and shape. Note that in addition to GUI 110, observer 112 may use the command-line interface with keyboard 105 to implement all of the functionality accessible via GUI 110. The command-line interface offers additional speed, compactness, and flexibility. GUI 110 allows observer 112 to take control of virtually every aspect of the visual environment of display 102. Observer 112 may select from a set of pre-define objects, as well as importing a custom object. In addition, observer 112 may select two objects to additionally test for artifacts caused by the interaction of the two objects. In one embodiment of the present invention, observer 112 may set the motion type of the object to linear, linear oscillation, or sinusoidal oscillation. During sinusoidal oscillation, the object moves the fastest through the center of oscillation, and the slowest at the end points. In the instances where oscillation is chosen, observer 112 can choose the width and the frequency of oscillation. Additionally, observer 112 can change the direction of motion as well as the speed. In one embodiment of the present invention, speed is referred to as pixels per refresh, or simply the number of pixels the object moves on the display for each refresh cycle of the display. Since the display size and refresh rate is known to the program, speed can also be expressed in various other terms, such as inches per second. In one embodiment of the present invention, observer 112 may use GUI 110, as well as clicking and dragging portions of the object itself to alter the object's geometry. GUI—Color Configuration FIG. 4 illustrates the color configuration portion of GUI 110 in accordance with an embodiment of the present invention. GUI 110 allows observer 112 to set various attributes related to the color of the object being used to test display 102. These attributes can include line colors, foreground colors, background colors, and gradient shading. Note that it is important to consider color when testing a display for motion-produced artifacts. Since pixels on a display may exhibit different response times to turn on or off for different colors, distortions may not be noticeable for one set of colors, but may be extremely noticeable with another set of colors. GUI—Measurement Configuration FIG. 5 illustrates the measurements configuration portion of GUI 110 in accordance with an embodiment of the present invention. GUI 110 allows observer 112 to set various attributes related to the measuring of the artifacts produced on display 102. These attributes can include the types of measurement rulers, the colors of the rulers, and the deltas of the rulers. When observer 112 notices an artifact or distortion, observer 112 may choose to measure the distortion by displaying rulers along with the object that is being distorted. In one embodiment of the present invention, one ruler is placed along the leading edge of the moving object, and another ruler is placed on the trailing edge. The rules may be widened, represented by the delta value, to cover the area of the distortion. Once the ruler covers the distortion completely, the delta value indicates the amount of distortion caused by the moving object with a specific set of visual attributes. The delta value can then be used to compute the response times for the pixels under the given visual attributes. Note that the ruler on the leading edge measures the response time for the pixels to turn on, while the trailing edge ruler measures the response time for the pixels to turn off. Note that rulers can be any shape or size including, but not limited to, lines, shapes, background images, and multiple lines. Also note that the rulers may be oriented in any direction and attached to any portion of the artifact. In one embodiment of the present invention, the rulers may be displayed at every n refresh cycles of display 102. This allows for greater accuracy in measuring the distortion by minimizing motion artifacts caused by the rulers moving. Testing Displays for Motion Artifacts FIG. 6 presents a flow chart illustrating the process of testing a display for motion artifacts in accordance with an embodiment of the present invention. A video image is generated which shows an object moving across display 102 in time. An ideal display will produce the object precisely, with no temporal degradation. Display 102 may have latency, response time limitations, real time processing (timing) difficulties, real-time color rendering delays, and a host of other temporal processing inaccuracies which may contribute to reproducing the content with distortions, or artifacts. The moving object may be visible on display 102 producing artifacts of various types, including flickering, flashing, smearing, distorting, producing inaccurate colors, etc. These are all undesired temporal distortions. Ideally, the object should look exactly the same to observer 112 while the object is in motion and while the object is still. In addition, the object should look the same over time and be free from temporal distortions that are not motion-induced. The distortion in such a case can be easily observed. However, the characteristics of the human visual system can contribute to some perceptions of distortion that may not actually be generated on display 102. It is a major part of this program to provide enough tools and control to help definitively assess the motion distortion using other than the eye of observer 112. The system starts by producing an image (step 602) and displaying the image on display 102 (step 604). Note that the image can include a pre-defined image such as a line, a hollow box, a filled box, a hollow ellipse, a filled ellipse, a hollow triangle, a filled triangle, random line patterns, or a custom image that observer 112 imports. Note that different images can produce different types of motion-induced artifacts. Observer 112 views the image (step 606) and manipulates the controls that produce the image via GUI 110, and or keyboard 105 and mouse 106, (step 608). As the image controls are manipulated, the system repeats steps 602 through 608. Upon discovering a noticeable artifact, the system may analyze the image (step 610), or provide adequate control for subjective determination of the artifact by observer 112. Note that the motion artifacts can be caused by any part or on any part of the display system. For example, in one embodiment of the present invention, artifacts may be observed that are the result of poor response time for pixels within an LCD display. Artifacts may also result from a flaw in the graphics processing circuitry or the software that generates the images for the display. Furthermore, artifacts may be observed that are the result of characteristics on the transmission lines between the graphics processor and the display such as cross-talk, amplitude dependencies, and skew. Measuring a Motion-Induced Artifact FIG. 7 illustrates measuring a motion-induced artifact in accordance with an embodiment of the present invention. Analysis of the image is a combination of the subjective, which requires the input of observer 112, and numerical analysis which is done by the system itself. Due to the dynamic nature of the system, observer 112 is able to constantly manipulate the attributes of the display system to detect and quantify any number of visual artifacts. In some instances, artifacts might be easily detectable but difficult to quantify, such as flickering of the object. In these cases, the system facilitates in producing artifacts so that subjective analysis and reporting can begin. One type of numerical analysis is performed by creating guides or rules along portions of the object being displayed. In one embodiment, one ruler (ruler 702) is created on the leading edge of moving object 700, and another ruler (ruler 704) is created on the trailing edge. By altering a delta value for each ruler, the width of the rulers can be changed to completely cover the area of distortion on each of the edges of the object. For instance, the delta value can be changed for ruler 702 until it completely covers artifact 706, and the delta value for ruler 704 can be changed until it completely covers artifact 708. Theoretically, the delta should remain at zero, even while object 700 is in motion. However, as motion is introduced and the various attributes of object 700 are modified, it is possible to measure the differences as the distortion occurs. This aids in quantifying the distortion in addition to describing the distortion. The delta of leading edge ruler 702 can be used to quantify the response time for the pixels to turn on for the given set of visual attributes. Likewise, the delta of trailing edge ruler 704 can be used to quantify the response time for the pixels to turn off for the given set of visual attributes. Note that it may be important for the rulers 702 and 704 to be displayed every nth refresh cycle so that distortion of the rulers in motion does not come into play. The foregoing descriptions of embodiments of the present invention have been presented for purposes of illustration and description only. They are not intended to be exhaustive or to limit the present invention to the forms disclosed. Accordingly, many modifications and variations will be apparent to practitioners skilled in the art. Additionally, the above disclosure is not intended to limit the present invention. The scope of the present invention is defined by the appended claims.
	abstract	A target shell monitoring device 4 that monitors an attitude and a position of the target shell Tg1, a compression laser output device 5a that irradiates the target shell Tg1 with a compression laser light LS1, and a heating laser output device 6 that irradiates the target shell Tg1 with a heating laser light LS3 following the compression laser light LS1 are provided. The target shell Tg1 has a hollow spherical shell shape, includes an approximately spherical space Sp on an inner side thereof, includes at least one through hole H1 connecting an outer side thereof and the space Sp, and includes, on an outer surface Sf1 thereof, irradiation areas Ar1 and Ar2 to be irradiated with compression laser lights.
	abstract	An investigative X-ray apparatus comprises a source of X-rays emitting a cone beam centred on a beam axis, a collimator to limit the extent of the beam, and a two-dimensional detector, the apparatus being mounted on a support which is rotatable about a rotation axis, the collimator having a first state in which the collimated beam is directed towards the rotation axis and the second state in which the collimated beam is offset from the rotation axis, the two-dimensional detector being movable accordingly, the beam axis being offset from the rotation axis by a lesser amount than the collimated beam in the second state. The X-ray source is no longer directed towards the isocentre as would normally be the case; the X-ray source is not orthogonal to the collimators. This is advantageous in that the entire field of the X-ray tube can be utilised. As a result, a lesser field is required of the X-ray tube and the choice of tube designs and capacities can be widened so as to optimise the performance of the X-ray tube in other aspects.
046559965	description	DETAILED DESCRIPTION OF THE INVENTION FIG. 1 is a sectional view of a fast neutron nuclear reactor 1 having a storage structure in accordance with the present invention. The nuclear reactor 1 comprises a vertically axed vessel 2, suspended on a horizontal slab 4 and filled with a liquid cooling metal 5, generally sodium. The level of the liquid sodium is surmounted by a layer of inert gas, normally argon. The horizontal slab 4 rests on a thick-walled concrete enclosure 6. The reactor core 8 placed inside a supplementary vessel or internal vessel 9, which defines two separate regions in main vessel 2, is immersed in the liquid sodium 5. It is essentially constituted by fuel assemblies and fertile assemblies. The right-hand half-view shows a special construction of the nuclear reactor vessel. This is characterized by the fact that it has a cylindrical ferrule or baffle 11 leaving a first annular space between it and vessel 2. Within baffle 11, there is a second ferrule 13, which is also called a counterbaffle, leaving between it and baffle 11 a second annular space. The annular space between vessel 2 and baffle 11 is used for supplying cold liquid metal. The annular space between baffles 11 and 13 is used for the removal thereof. A nuclear reactor of this type is described in French Pat. No. 7,536,226, filed on Nov. 26, 1975 in the name of the Commissariat a l'Energie Atomique and entitled "Nuclear reactor". No matter what the reactor vessel construction, i.e. no matter whether it does or does not have a baffle and a counter-baffle, the assemblies 10 are fixed into a structure 21 integral with a flooring 27, which rests on the bottom of vessel 2. The nuclear reactor has means making it possible to ensure the circulation of liquid cooling metal. These means are constituted by circulating pumps 24 (FIGS. 1 and 2) and exchangers 25 arranged on the periphery of vessel 2. At the outlet of pump 23, the sodium is introduced under high pressure at the base of the assemblies and traverses the latter from bottom to top in order to leave it in the upper part of the core. Thus, the internal vessel 9 defines a cold collector 14 located in the lower part of the vessel and a hot collector 15 in the upper part thereof. At the core inlet, the sodium has a temperature of approximately 400.degree. C. and a temperature of approximately 550.degree. C. at its outlet. The heat accumulated during the passage in the core is transferred into heat exchangers 25. Sodium passes through these exchangers from top to bottom and leaves them in the lower part, passing into the cold collector, where it is again drawn in by the circulating pumps for reintroduction into the structure. Nuclear reactor 1 has a storage structure 31 for the assemblies independent of the core structure 31. Structure 31 rests directly on flooring 27, by which it is hydraulically supplied with cold liquid metal. Therefore, it constitutes an autonomous structure independent of structure 21. It is arranged concentrically within the latter. As can be seen in FIG. 2, the cold liquid metal is drawn into collector 14, i.e. beneath the separating partition 9, in the manner shown by arrow 33 and is then delivered in accordance with arrow 35 into the core structure for introduction into the feet or bases of the fuel assemblies 10, in the manner indicated by arrow 37. Between assemblies 10 of the core and those of the storage structure 31, there are the assemblies constituting the lateral neutron protection resting on the core structure 21 via a false structure 22. Pipes 39, which connect pumps 24 to structure 21, traverse the flooring 27. In order that these pipes can be housed in the height remaining available in the storage structure 31, their cross-section can be flattened so as to have an elliptical shape, as is shown in detail a, which shows a pipe 39 and its cross-section in mixed line form, as well as the passage 40 made in flooring 27 for said pipe. The core structure can also be supplied through the storage structure by splitting the supply pipe into smaller diameter pipes (FIG. 5). Another variant consists of supplying the core structure from below through the flooring (FIG. 6). FIG. 3 is a diagrammatic cross-sectional view along line IV--IV of FIG. 1 of the nuclear reactor equipped with a storage structure 31 according to the invention. As can be seen, the storage structure is in two parts, each of them being shaped like a half-ring. One of the spaces, in this case 33, located between these two half-rings is left sufficiently wide to permit the installation of the reactor loading and unloading station. Thus, during the unloading operation, assemblies are extracted from core 8 and transferred by means of a handling arm, as indicated by arrows 43 (FIGS. 1 and 3) into a handling container 41 of the loading and unloading stations arranged at the periphery of core 8. Container 41 can move on an oblique ramp 46 passing into the interior of vessel 2 and traversing the upper slab 4. The space 33 left free by the two half-rings forming storage structure 31, makes it possible to move the loading and unloading station 41 close to the core periphery and consequently reduce the dimensions, particularly the external diameter, of vessel 2. This makes it possible to considerably reduce the cost of the reactor. FIG. 3 also shows the arrangement of the pumps and exchangers concentrically to the core. Only one pump 24 and one exchanger 25 are shown, in order not to overburden the drawing. The broken lines indicates the circulation of the liquid cooling metal. Arrow 45 (FIGS. 1 and 3) indicates the drawing in or suction of the hot liquid metal from the core into the heat exchanger 25. Arrow 33 (FIGS. 2 and 3) indicates the delivery under pressure of the cooled liquid metal, after its passage in the exchangers, into the core structure 21. FIG. 3 also shows a pipe 39 connecting pump 24 to core structure 21. In order to illustrate the way in which the cold liquid metal leaks are produced in the direction of the flooring, FIG. 4 shows the way in which the fuel assemblies are maintained in a core structure. Naturally, this is only an example and other modes of fixing these assemblies could be envisaged. Structure 21 comprises two perforated plates 21a, 21b, into which are fitted stays 19. The foot 10a of assembly 10 is introduced into each stay, which ensures the supporting of assembly 10, as well as the cold liquid sodium supply to the foot of the assembly through oblong holes 16, 17 made at the same level in the stay and the foot of the assembly. In order to ensure the hydraulic locking of assembly 10, on the outerface of its foot and on either side of the oblong supply holes 16, 17 are provided labyrinths 10b, 10c. However, the sealing at these labyrinths is only relative, so that there is a leakage flow to the flooring, as described hereinbefore. Moreover, it should be noted that the liquid sodium which passes through labyrinth 10b undergoes a pressure drop, in such a way that the pressure in flooring 27 and storage structure 31 is much lower than that in core structure 21. This low pressure cold liquid metal supplies the bases or feet 49 of the stored assemblies. In addition, the pressure within the storage structure is slightly higher than that in the hot collector. Thus, there is a forced circulation of cold liquid metal from bottom to top in the stored assemblies, as indicated by arrow 51 in FIG. 2. An effective cooling of the stored assemblies consequently ensures a good evacuation of the residual power. In the case of the constructional variant of the reactor shown in the right-hand half-view of FIG. 1, i.e. the variant having a baffle 11 and a counter-baffle 13, the leaks of the assembly feet are also used for supplying cold liquid metal to the annular space between main vessel 2 and baffle 11. This is obtained by producing two independent leak recovery areas beneath the core structure 21, one supplying the annular space of baffle 11 and the other the storage structure 31, as indicated by the arrows in FIG. 1. As the manufacturing tolerances are greater and as the clearances between the stored assemblies and the lateral neutron protection assemblies can be greater in order to accept large bending or cambering effects, the precision of the construction of the storage structure 31 can be reduced, which reduces manufacturing costs. Another advantage of the storage structure according to the invention is that as the latter is at low pressure, it is possible to use larger diameter flow rate control openings and thus to eliminate risks of blockages, unlike in the case of the high pressure storage structure according to the prior art which, to obtain low liquid cooling metal flow rates in the stored assemblies, required small diameter flow rate control openings. With regards to the reduction of the diameter of the core structure 21 within which a high pressure prevails, it should be noted that the invention makes it possible to reduce it to the indispensable minimum. For example, for a reactor of 1500 MWe, the diameter of this high pressure structure passes from 8.25 to 6.50 m which, as indicated hereinbefore, makes it possible to pass this structure through a small diameter opening of the rotary plug. The location of the loading and unloading station on a radius equal to that of the storage structure 31 makes it possible to reduce the diameter of the main vessel and access vertically of the loading and unloading container with a large rotary plug with a diameter of 10 m, whereas hitherto it was 11.2 m for a reactor of 1500 MWe. Finally, this makes it possible to reduce the length of the handling arms of the assemblies and the angular travel of said arm. It must be possible to introduce the structure through the hole provided in slab 4 for receiving the large rotary plug. The reduction in the diameter of structure 21 from 8.25 to 6.50 m reduces to the same extent the limit of the minimum diameter of the large rotary plug resulting from this constraint. Thus, the minimum diameter of the large rotary plug decreases from 9 to 7.25 m. Unlike in the prior art, where the loading and unloading station of the core was in the lateral neutron protection, the invention has the advantage of positioning this station outside said protection and consequently ensures the continuity of the protection over the entire core periphery.
	summary
044329423	claims	1. An apparatus, for filling a container with radioactive waste, comprising: (i) a furnace body having a top wall with an opening therein and a side wall with an opening therein at an upper part thereof, said body being open at its lower part, (ii) a lower cover adapted, when in a raised position, to close said open lower part of the body, (iii) a container on said lower cover which becomes positioned in said body when said cover is in its raised position, (iv) means for raising and lowering said lower cover, (v) a bucket movable through said side wall opening between a first position in which it is outside said side wall of the furnace body, and a second position in which it is located above said container in said body, (iv) plasma torch means movable up and down through said top wall opening between a raised position in which said torch means are raised in said furnace body so that a lower end thereof becomes positioned above the level of said bucket, and a lowered position in which said lower end extends into said container when said container is positioned in said body. 2. An apparatus, as claimed in claim 1, comprising door means positioned for closing and opening said side wall opening. 3. An apparatus, as claimed in claim 1, comprising means in said furnace body for directing cooling gas onto said container in said furnace body. 4. An apparatus, as claimed in claim 1, wherein said container is lined with graphite. 5. An apparatus, as claimed in claim 1, wherein said container comprises an iron canister, a layer of concrete lining said canister, and a layer of graphite within said concrete forming a crucible.
	abstract	The present invention is directed to a method and apparatus for CT data acquisition using a rotatable pre-subject filter having more than one filtering profile to control radiation exposure to a subject. The filter is caused to rotate by a motor and bearing assembly and has one profile used to filter radiation when the radiation source is positioned above a subject and another profile that is used to filter radiation when the radiation source is positioned at a side of the subject.
	summary
	summary
	abstract	An apparatus that acts as a shield for radiopharmaceuticals and protects individuals from radioactivity includes a first body with a first hollow core, a second body with a second hollow core and a third body with a third hollow core. The first hollow core, second hollow core and third hollow core collectively house a hypodermic syringe. A first connection means releasably communicates the first body with the second body. A second connection means releasably communicates the first body with the third body. The third body comprises means for lowering the hypodermic syringe into a well counter to measure radioactivity of the radiopharmaceutical it contains.
	description	This disclosure generally relates to the technical field of control rod position measurement for nuclear power plants, and more particularly, to full-digital control rod position measurement devices and methods thereof. Rapid regulation of reactor power is achieved primarily through controlling the lifting and lowering of the control rod cluster, wherein the lifting and lowering of the rod cluster are controlled by a rod control system. However, conventional rod control system does not comprise a feedback mechanism capable of verifying whether the rod cluster control command has been executed correctly. As a result, a rod position measurement system is typically used to obtain the actual position of the rod cluster, monitor the operation of the rod control system, and complete the precise positioning of the control rod cluster. As shown in FIGS. 2-5, taking the Qinshan phase II nuclear power plant as an example, the conventional rod position measurement system comprises thirty-three rod position detectors, two measurement cabinets, a distribution cabinet, a processing cabinet, and a rod position display (including thirty-three rod position display modules). The rod position detectors are located above a control rod driving mechanism, which is located on top of a reactor in a containment. The measurement cabinets and distribution cabinet are located in room L609/649 at a height of 15.5 meters (m) in an electrical power plant, the processing cabinet is located in room W228/268 at a height of 0 m in a connection building, and the rod position display is located in main control room. The measurement cabinets are used to provide an excitation to a primary coil of a detector, and shape the induced voltage signal of a measurement coil of the detector, thereby a Gray code signal indicating a rod position may be obtained. On one hand, the Gray code may be sent to the processing cabinet for comparison and processing. On the other hand, the Gray code may be converted into a binary code, which may be sent to the main control room for display after photoelectric isolation. The conventional rod cluster control assembly and its driving shaft are located in an environment with high temperature and high pressure created by the nuclear reactor. The position measurement typically utilizes the electromagnetic induction principle and is performed using conventional rod position detectors. A conventional rod position detector typically comprises a primary coil, a measurement coil, an auxiliary coil, a coil frame, a sealing shell, and an outer sleeve. Taking the Qinshan phase II nuclear power plant as an example, the rod position detector has a total length of 4006 millimeters (mm), an inner diameter of 154 mm and an outer diameter of 300 mm. The primary coil is a long solenoid coil, which has about 2000 turns, a wire diameter of 1.97 mm, and is wound along the entire stroke. The measurement coil and the auxiliary coil are both secondary coils, and each of which has 1700 turns, a width of 2 centimeters (cm), a wire diameter of 0.23 mm, and is coaxial with the primary coil. The primary coil is used to generate an alternating magnetic field, the measurement coil is used to form the rod position code, and the auxiliary coil is used to adjust the current of the primary coil. The driving shaft is made of a magnetic material, while the sealing shell, the coil frame, and the outer sleeve of the detector, as well as other components in the detector, have a relatively low magnetic conductivity. Under such circumstances, whether the driving shaft passes through the measurement coil can greatly affect the induced voltage, and whether the top end of the driving shaft is above or below the measurement coil can be known through monitoring the induced voltage of the measurement coil at a particular position. As long as a sufficient number of measurement coils are arranged to monitor the induced voltage of each coil, the position of the control rod driving shaft can be roughly determined. To roughly determine the position of the control rod, a sufficient number of measurement coils may be arranged. The number and the spacing of measurement coils are determined according to the stroke length of the driving shaft and the desired resolution. Moreover, to reduce the number of wiring between detectors and signal processing channels, and to reduce the number of signal processing devices, the measurement coils may be grouped. Taking the Qinshan phase II nuclear power plant as an example, the length of each mechanical step of the control rod driving shaft is 15.875 mm. The full stroke is 228 mechanical steps. The resolution of the detector is 8 mechanical steps, which corresponds to 127 mm. There are 31 measurement coils, which are divided into five groups including A, B, C, D and E. The whole measurement stroke is 256 mechanical steps. The measurement coils are grouped as follows: First, when a measurement coil C1 is wound at the ½ height of the detector's measurement stroke, through monitoring its induced voltage (effective value, the same as below) V1, it can be known whether the rod position is in the section [0, 128) or [0, 256). Further, when coils C21 and C22 are respectively wound at ¼ and ¾ height of the detector's whole measurement stroke, through monitoring the induced voltage V21 of C21, it can be known whether the rod position is in the section [0, 64) or [64, 128), and through monitoring the induced voltage V22 of C22, it can be known whether the rod position is in the section [128, 192) or [192, 256). Actually, these three coils have divided the whole measurement stroke into 4 sections with equal length. By monitoring the induced voltages of these three coils, it can be known which section the rod position is in, wherein the induced voltage level and the corresponding rod position are shown in the following table: Induced Voltage“Position ofV21V1V22Section of Rod PositionRod Cluster”LowLowLow [0, 64)0HighLowLow [64, 128)1HighHighLow[128, 192)2HighHighHigh[192, 256)3 When coils C21 and C22 are series-opposing connected into a group (referred to as C2), for V21 and V22 are always in the same phase, the output voltage of C2 is V2=\|V21−V22\|, wherein the induced voltage level and the corresponding rod position are shown in the following table: InducedVoltageAfter ShapingSection of Rod“Position ofV1V2Low→0,High→1PositionRod Cluster”LowLow00 [0, 64)0LowHigh01 [64, 128)1HighHigh11[128, 192)2HighLow10[192, 256)3 Similarly, when coils C31, C32, C33 and C34 are respectively wound at ⅛, ⅜, ⅝ and ⅞ height of the detector's whole measurement stroke, and are connected in series to form a group C3, the whole measurement stroke can be divided into 8 sections with equal length. Through monitoring the three voltages V1, V2 and V3 (=\|V31−V32+V33−V34\|), it can be known which section the rod position is in, and the measurement resolution can reach 32 steps. Further, when eight coils C41, C42 . . . and C48 are respectively wound at 1/16, 3/16, 5/16, 7/16, 9/16, 11/16, 13/16 and 15/16 height of the detector's whole measurement stroke, and are connected in series to form a group C4, the whole measurement stroke can be divided into 16 sections with equal length. Through monitoring the four voltages V1, V2, V3 and V4 (=\|V41−V42+V43 . . . −V48\|), it can be known which section the rod position is in, and the measurement resolution can reach 16 steps. Further, when 16 coils C51, C52 . . . and C516 are respectively wound at 1/32, 3/32, 5/32 . . . and 31/32 height of the detector's whole measurement stroke, and are connected in series to form a group C5, the whole measurement stroke can be divided into 32 sections with equal length. Through monitoring the five voltages V1, V2, V3, V4 and V5 (=\|V51−V52+V53 . . . −V516\|), it can be known which section the rod position is in, and the measurement resolution can reach 8 steps. Generally, groups C1, C2, C3, C4 and C5 are respectively called group E, D, C, B and A. If the coils are numbered from low to high according to their positions, the respective coils in each group are: Coil in Group E:16Coils in Group D:824Coils in Group C:4122028Coils in Group B:26101418222630Coils in Group A:135791113151719212325272931 The structure of the detector and the coil numbers are shown in FIG. 2. If the excitation voltage of the primary coil of the detector is constant, the impedance in the circuit increases and the current of the primary coil decreases as the control rod driving shaft moves upward. The actual measurement shows that if the current of the primary coil remains unchanged, the induced voltage of the measurement coil when the rod position is at 100 steps is about 10% lower than that when the rod position is at 0 step. In addition, when the reactor is in cold and thermal working conditions, the impedance of the rod position detector varies greatly due to the variation of the ambient temperature. If the magnetic field is not kept constant, the measurement accuracy can be affected. FIG. 3 is a diagram showing the offset of the measurement boundary point caused by the variation of magnetic field strength. FIG. 4 is a block diagram showing an excitation control circuit of the primary coil, which is a high-power audio amplifier circuit. The amplitude of 50 Hz sine wave is regulated by a digital potentiometer, which is controlled by the frequency signal formed by the difference between the given value and the measured value of the auxiliary coil voltage. The other way is to connect a large resistor in series in the primary excitation circuit instead of arranging an automatic control circuit, thereby making the impedance change caused by the change of the driving shaft position and the change of the detector's ambient temperature small enough to be ignored in the total impedance. The circuit of the former is complex and inevitably has a large number of components. Moreover, the temperature of the measurement clamping piece is high, and the reliability is low. Although the primary circuit of the latter is simple, the power consumption is high, and the measurement precision is low. The signal processing process of the secondary measurement coil may adopt a filter circuit, a shaping circuit, and a threshold comparison circuit. The processing process is shown in FIG. 5 (taking the coils in group D as an example). One concern about the processing process is that there are many components, which causes long delay time of filter shaping. Additionally, the threshold voltage needs to be adjusted by repeatedly lifting and lowering the control rod when the reactor is initiated, which occupies the critical path of the refueling outage for a long time. The present disclosure provides a digital rod position measurement device, which can effectively reduce the complexity of the detector's primary excitation circuit and secondary measurement signal processing circuit, simplify the threshold setting mode of rod position processing, and improve the reliability and measurement accuracy of rod position processing equipment. The purpose of the present disclosure is to provide a full-digital control rod position measurement device and a method thereof, which can effectively reduce the complexity of the primary excitation circuit and the secondary measurement signal processing circuit of the detectors, and improve the operation reliability and measurement accuracy of the rod position processing equipment. To achieve the above purpose, the present disclosure adopts the following technical solution: A full-digital rod position measurement device, comprising: an excitation power supply, and a universal signal processor, wherein the excitation power supply provides a working power supply to primary coils of rod position detectors located within a containment, wherein the universal signal processor collects signals output from the rod position detectors, and the signals output from the rod position detectors comprise voltage signals of the primary coils, current signals of the primary coils, voltage signals of measurement coils of each group of a plurality of group, and voltage signals of auxiliary coils of each group of the plurality of group, wherein the universal signal processor processes the output signals from the rod position detectors according to a preset algorithm to compensate a variation of magnetic field strength of the rod position detectors, and simultaneously outputs control rod position signals. In another preferred embodiment, the universal signal processor collects the universal signal processor collects voltage signals of the auxiliary coils of the rod position detectors, collects current signals of the primary coils of the rod position detectors, calculates voltage amplitudes of the auxiliary coils according to the voltage signals of the auxiliary coils, calculates voltage amplitudes of the primary coils according to the current signals of the primary coils, calculates, for each group of a plurality of groups, a voltage amplitude of measurement coils of the respective group according to voltage signals of measurement coils of the respective group, and processes, for each group of the plurality of groups, the voltage signals of measurement coils of the respective group using the voltage amplitude of the auxiliary coils of the respective group or the current amplitude of the primary coils of the respective group to compensate a measurement signal fluctuation, wherein the universal signal processor compares the processed voltage of measurement coils of the respective group with a preset threshold voltage to form a control rod position signal. In another preferred embodiment, the excitation power supply adopts an AC transformer. In another preferred embodiment, a full-digital rod position measurement method, comprises: collecting output signals of rod position detectors using a universal signal processor, wherein the output signals comprise voltages of primary coils, currents of the primary coils, voltages of measurement coils, and voltages of auxiliary coils; determining a calculation interval, wherein determining the calculation interval comprises searching, by the universal signal processor, a starting point and a ending point of an avoidance interval that need to be avoided due to interference of control rod motion in determining the avoidance interval according to the voltages of auxiliary coils, assigning the ending point of the avoidance interval to be a starting point of the calculation interval, and assigning a point located 400 milliseconds behind the ending point of the avoidance interval to be an ending point of the calculation interval, and recording the avoidance interval between the starting point of the avoidance interval and the ending point of the avoidance interval, and recording the calculation interval between the ending point of the avoidance interval and the ending point of the calculation interval; for each group of a plurality of groups, calculating, by the universal signal processor, an average voltage of the auxiliary coils in the respective group in the calculation interval or an average current of the primary coils in the respective group in the calculation interval; for each group of the plurality of groups, calculating, by the universal signal processor, an average voltage of the measurement coils in the respective group in the calculation interval; for each group of the plurality of groups, calculating, by the universal signal processor, an voltage correction value of the measurement coils in the respective group, wherein the voltage correction value is calculated by dividing the average voltage of the measurement coils in the respective group by the average voltage of the auxiliary coils in the respective group, or dividing the average voltage of the measurement coils in the respective group by the average current of the primary coils in the respective group; and for each group of the plurality of groups, comparing, by the universal signal processor, the voltage correction value of the measurement coils in the respective group with a preset threshold voltage to form a control rod position signal. In another preferred embodiment, determining the calculation interval further comprises assigning the calculation interval to be 400 milliseconds when the avoidance interval cannot be searched by the universal signal processor. In another preferred embodiment, calculating the respective average voltage of the auxiliary coils in the respective group in the calculation interval or the respective average current of the primary coils in the respective group in the calculation interval comprises using fast Fourier transform or average peak-to-peak value calculation. Marking instructions of the figures: 10-Excitation Power Supply, 11-AC Transformer, 20-Integrated Interface Board, 30-Universal Signal Processor, 40-Rod Position Detector, 41-1-The First Primary Coil Terminal, 41-2-The Second Primary Coil Terminal, 42-The First Auxiliary Coil Terminal, 43-The Second Auxiliary Coil Terminal, 44-Group A Measurement Coil Signal Terminal, 45-Group B Measurement Coil Signal Terminal, 46-Group C Measurement Coil Signal Terminal, 47-Group D Measurement Coil Signal Terminal, 48-Group E Measurement Coil Signal Terminal, 49-Measurement Coil Common Terminal, 50-Rod Position Processing Cabinet, 60-Main Control Room Analog Indicator Board, 71-Sampling Resistor, 72-Short-circuit-proof Fuse, 73-Rod Drop Test Switch The present disclosure describes a full-digital control rod position measurement device and a method thereof. Preferred embodiments are combined hereinafter to further elaborate the implementation of the techniques of this disclosure. FIG. 1 shows the module structure of a full-digital control rod position measurement device 100. Preferably, the full-digital control rod position measurement device comprises an excitation power supply 10 and a universal signal processor 30, wherein the excitation power supply 10 provides a working power supply to the primary coils of the rod position detectors located within the containment, wherein the universal signal processor 30 collects the signals output by the rod position detectors. The signals output by the rod position detectors comprise the voltage signals of the primary coils, the voltage signals of measurement coils of each group of a plurality of groups, and the voltage signals of the auxiliary coils of each group of the plurality of groups. The universal signal processor 30 processes the output signals of the detectors according to a preset algorithm, thereby compensating for the variation of magnetic field strength of the rod position detectors, and simultaneously outputs the control rod position signals. According to the aforesaid technical solution, the universal signal processor 30 collects the voltage signals of the auxiliary coils of the detectors, calculates the voltage amplitudes of the auxiliary coils according to the voltage signals of the auxiliary coils, calculates the voltage amplitudes of the measurement coils of each group according to the voltage signals of the measurement coils of each group. For each group, the universal signal processor 30 processes the voltage signal of the measurement coils of the respective group using the voltage amplitude of the auxiliary coils of the respective group, thereby compensating for the measurement signal fluctuation caused by the variation of measurement conditions. For each group, the universal signal processor 30 respectively compares the processed voltages of measurement coils of the respective group with the preset threshold voltage, thus forming a respective control rod position signal. According to the aforesaid technical solution, the excitation power supply 10 adopts an AC transformer 11. According to the aforesaid technical solution, the universal signal processor 30 adopts the Compact RIO platform developed by National Instruments Corporation, USA. FIG. 7 shows the connection mode of the full-digital control rod position measurement device 100. Preferably, the excitation power supply 10 adopts an AC transformer 11 (excitation power transformer). The full-digital rod position measurement device 100 is provided with a rod drop test point, and further comprises a sampling resistor 71, a short-circuit-proof fuse 72 and a rod drop test switch 73. The output end of the AC transformer 11 is electrically connected with the input side of the rod drop test switch 73, and the short-circuit-proof fuse 72 and the sampling resistor 71 are sequentially connected in series between the output end of the rod drop test switch 73 and the rod drop test point. As shown in FIG. 7, preferably, the rod position detector 40 is provided with a first primary coil terminal 41-1, a second primary coil terminal 41-2, a first auxiliary coil terminal 42, a second auxiliary coil terminal 43, signal terminals 44-48 of measurement coils of groups A to E, and a measurement coil common terminal 49. Preferably, the preset numerical processing algorithm is to compensate for the position deviation of the control rod and the variation of the ambient temperature according to the measurement voltage signals of the auxiliary coils. In other words, the universal signal processor 30 forms control rod position signals in the form of Gray code (hereinafter referred to as Gray code rod position signals) through threshold comparison according to the collected voltages of the auxiliary coils and the collected voltages of measurement coils of each group. Specifically, the output signals of the rod position detectors comprise, but are not limited to, the voltage signals of the primary coils, the current signals of the primary coils, the voltage signals of the measurement coils of each group of a plurality of groups, and the voltage signals of the auxiliary coils of each group of the plurality of groups. For each group, the universal signal processor 30 calculates an average voltage amplitude of the auxiliary coils of the respective group according to the voltage signals of the auxiliary coils of the respective group. The universal signal processor 30 also calculates an average voltage amplitude of the measurement coils of the respective group according to the voltage signals of the measurement coils of the respective group, and performs a homogenization processing according to the average voltage amplitude of the auxiliary coils of the respective group. The universal signal processor 30 then compares the homogenized average value of voltage amplitude of the of measurement coils of the respective group with the preset threshold voltage, thereby forming a Gray code rod position signal. Preferably, the integrated interface board 20 is provided with a bus latch (not shown). The rod position processing cabinet 50 may provide nine strobe signals, and the universal signal processor 30 may output the Gray code rod position signals to the rod position processing cabinet 50 through the bus latch according to the strobe signals. Alternatively, the universal signal processor 30 may also output signals reflecting the operational failure of the rod position measurement device to the rod position processing cabinet 50, and the outputted signals may show “the measurement channel being under test” of each rod cluster, etc. Preferably, the full-digital rod position measurement device 100 also transmits the Gray code rod position signals to a main control room analog indicator board 60 through the integrated interface board 20 for analog indication. According to the aforesaid embodiment of the present disclosure, the full-digital rod position measurement device 100 switches among an automatic correction state, an operation state, and a test state. When the full-digital rod position measurement device 100 is in the automatic correction state, the measurement channel may be automatically corrected under the thermal working condition after the reactor overhaul, thereby obtaining the setting threshold of each group of measurement coils. The obtained threshold may be stored in a setting results file (to be used after the equipment failure maintenance). When the full-digital rod position measurement device 100 is in the operation state (e.g., a state it switches into after the correction is completed), the measurement position of the control rod may be determined according to the measurement signals and the setting threshold. During the normal operation of the reactor, when performing the regular test of the rod position measurement channel, the full-digital rod position measurement device 100 may switch to the test state and perform the channel correction 0, correction 1, and the continuous change test of the output rod position. As shown in FIG. 7, the signals required to be processed by the full-digital rod position measurement device are as follows: 1. 75 analog input signals 1) Each rod position detector 40 has 8 analog input signals (9 rod position detectors and 72 analog input signals in total), which respectively are: a) Primary coil voltage Up; b) Primary coil current Ip; c) Auxiliary coil voltage Uaux; d) Group A coil voltage Ua; e) Group B coil voltage Ub; f) Group C coil voltage Uc; g) Group D coil voltage Ud; h) Group E coil voltage Ue; 2) The analog input signals for monitoring the internal working power of the case are preferably 3 analog input signals. 2. 9 switch input signals 9 strobe signals (switch input signals) are provided by the rod position processing cabinet 50. 3. 61 switch output signals 1) 9 “rod cluster being under test” signals output to the rod position processing cabinet 50; 2) 5-bit Gray code signal and 1 bus switch signal output to the rod position processing cabinet 50; 3) “Equipment failure” signal output to the rod position processing cabinet 50; 4) 9 5-bit Gray code rod position signals output to the main control room. Preferably, according to the requirements of input and output channel numbers and system performance, the universal signal processor 30 adopts the Compact RIO platform developed by National Instruments Corporation, USA. As shown in FIG. 9, curve P10 in FIG. 9 is the auxiliary voltage waveform, curve P20 is the group A measurement voltage waveform, P11 is the auxiliary voltage mean line, and P21 is the group A measurement voltage mean line (the group A measurement voltage waveform is taken as an example herein, and the rest groups of measurement voltage waveforms are handled in the same manner). The present disclosure also describes a full-digital rod position measurement method, wherein through searching an avoidance interval AB interfered by the control rod motion, the avoidance interval AB is avoided when calculating the voltages of measurement coils of each group of a plurality of groups, thereby obtaining voltage signals of measurement coils in each group that represent the actual position of the control rod, wherein the above groups of measurement coil voltage signals are used as the basis for judging the actual position of the control rod, comprising the steps of: Step S1: collecting the signals of detectors: the universal signal processor collects the output signals of the rod position detectors, wherein the output signals of the rod position detectors comprise the voltage signals of the primary coils, the voltage signals of measurement coils of each group, and the voltage signals of the auxiliary coils of each group; Step S2: determining the calculation interval: according to the auxiliary coil voltage signals, the universal signal processor searches for the starting point A and the ending point B of the avoidance interval that need to be avoided due to the interference of the control rod motion in the searching interval; the ending point B of the avoidance interval is regarded as the starting point of the calculation interval, and the point located 400 ms behind the ending point of the avoidance interval is regarded as the ending point C of the calculation interval; the interval between the starting point A of the avoidance interval and the ending point B of the avoidance interval is recorded as the avoidance interval AB, and the interval between the ending point B of the avoidance interval and the ending point C of the calculation interval is recorded as the calculation interval BC; Step S3: calculating the voltages of auxiliary coils: the universal signal processor calculates the average value of voltage amplitudes of the auxiliary coils in the calculation interval BC; Step S4: calculating the voltages of measurement coils of each group: the universal signal processor calculates the voltage amplitude average value of measurement coils of each group in the calculation interval BC; Step S5: calculating the voltage correction value of the measurement coil of each group: for each group of the plurality of groups, the universal signal processor divides the average voltage of the measurement coils of the respective group by the average voltage of the auxiliary coils of the respective group, thereby obtaining a voltage correction value of measurement coils of the respective group; Step S6: comparing the thresholds: the universal signal processor compares the voltage correction value of the above groups of measurement coils with the preset threshold voltage, thereby forming the control rod position signals. In step S2, when the avoidance interval AB cannot be searched by the universal signal processor, the last 400 ms of the searching interval is taken as the calculation interval BC. According to the aforesaid embodiment, one full-digital rod position measurement device 100 can realize the parallel data collection and control processing of 72 analog signals of 9 rod position detectors at the same time, capable of storing and displaying the failures, abnormalities and waveforms containing abnormal variations. Thus, the relevant requirements of rod position measurement processing can be satisfied. It is worth mentioning that, through adopting the full-digital rod position measurement device according to the present disclosure, the threshold setting of the measurement channel and the appraisal of the measurement performance can be completed when the control rod is lifted and lowered for one stroke, and the occupation time of the critical path of refueling outage can be shortened to be within one third of the original time occupied by the performance appraisal of the rod position system. The present disclosure also discloses another preferred embodiment. In this embodiment, the full-digital rod position measurement device comprises an excitation power supply and a universal signal processor, wherein the excitation power supply provides a working power supply to the primary coils of the rod position detectors located within a containment, wherein the universal signal processor collects the signals output from the rod position detectors, and the signals output from the rod position detectors comprise the voltage signals of the primary coils, the current signals of the primary coils, the voltage signals of measurement coils of each group of a plurality of groups, and the voltage signals of the auxiliary coils of each group of the plurality of groups, wherein the universal signal processor processes the output signals of the detectors according to a preset algorithm, thereby compensating for the variations of magnetic field strength of the rod position detectors, and simultaneously outputs the control rod position signals. According to the aforesaid technical solution, the universal signal processor collects the voltage signals of the auxiliary coils of the detectors, collects the current signals of the primary coils of the detectors, calculates the voltage amplitudes of the auxiliary coils according to the voltage signals of the auxiliary coils, calculates the voltage amplitudes of the primary coils according to the current signals of the primary coils. For each group of the plurality of groups, the universal signal processor calculates an voltage amplitude of the measurement coils of the respective group according to the voltage signals of the measurement coils of the respective group, and processes the voltage signals of measurement coils of the respective group by using the voltage amplitude of the auxiliary coils of the respective group or the current amplitude of the primary coils of the respective group, thereby compensating for the measurement signal fluctuation caused by the variation of measurement conditions. The universal signal processor respectively compares the processed voltage of the measurement coils of the respective group to the preset threshold voltage, thus forming a control rod position signal. According to the aforesaid technical solution, the excitation power supply adopts an AC transformer. As shown in FIG. 8, the present disclosure also discloses a full-digital rod position measurement method, wherein through searching the avoidance interval AB interfered by the control rod motion, the avoidance interval AB is avoided when calculating the voltages of measurement coils of each group, thereby obtaining each group of measurement coil voltage signals representing the actual position of the control rod, wherein the above groups of measurement coil voltage signals are used as the basis for judging the actual position of the control rod, comprising the steps of: Step S1: collecting the signals of detectors: the universal signal processor collects the output signals of the rod position detectors, wherein the output signals of the rod position detectors comprise the voltage signals of the primary coils, the current signals of the primary coils, the voltage signals of the measurement coils of each group of a plurality of groups and the voltage signals of the auxiliary coils of each groups of the plurality of groups; Step S2: determining the calculation interval: according to the auxiliary coil voltage signals, the universal signal processor searches for the starting point A and the ending point B of the avoidance interval that need to be avoided due to the interference of the control rod motion in the searching interval; the ending point B of the avoidance interval is regarded as the starting point of the calculation interval, and the point located 400 ms behind the ending point of the avoidance interval is regarded as the ending point C of the calculation interval; the interval between the starting point A of the avoidance interval and the ending point B of the avoidance interval is recorded as the avoidance interval AB, and the interval between the ending point B of the avoidance interval and the ending point C of the calculation interval is recorded as the calculation interval BC; Step S3: calculating the average voltage of the auxiliary coils of each group or average currents of the primary coils of each group: for each group of the plurality of groups, the universal signal processor calculates an average voltage of the auxiliary coils of the respective group in the calculation interval BC or an average current of the primary coils of the respective group in the calculation interval BC; Step S4: calculating the voltages of measurement coils of each group: for each group of the plurality of groups, the universal signal processor calculates an average voltage of measurement coils of the respective group in the calculation interval BC; Step S5: calculating the voltage correction value of measurement coils of each group: for each group of the plurality of groups, the universal signal processor divides the obtained average voltage of measurement coils of the respective group by the average voltage of the auxiliary coils of the respective group, thereby obtaining the voltage correction value of the measurement coils of the respective group, or divides the average voltage of the measurement coils of the respective group by the average current value of the primary coils of the respective group, thereby obtaining the voltage correction value of the measurement coils of the respective group; Step S6: comparing threshold: the universal signal processor compares the voltage correction value of measurement coils of the respective group with the preset threshold voltage, thereby forming a control rod position signal. According to the aforesaid full-digital rod position measurement method, in step S2, when the avoidance interval AB cannot be searched by the universal signal processor, the waveform of 400 ms in the searching interval is taken as the calculation interval BC. According to the aforesaid full-digital rod position measurement method, in step S3, the universal signal processor calculates the average voltage of the auxiliary coils of the respective group in calculation interval BC or the average current of the primary coils of the respective group in calculation interval BC by using fast Fourier transform or average peak-to-peak value calculation. Those skilled in the art may modify the technical solutions recorded in the aforesaid embodiments, or equally replace some of the technical features according to the specification of the present disclosure. Therefore, modifications, equivalent replacements and improvements made within the spirit and principles of the disclosure shall fall into the scope of the present disclosure.
	abstract	A nuclear reactor system that, in one embodiment, utilizes natural circulation to circulate a primary coolant in a single-phase through a reactor core and a heat exchange sub-system. The heat exchange subsystem is located outside of the nuclear reactor pressure vessels and, in some embodiments, is designed so as to not cause any substantial pressure drop in the flow of the primary coolant within the heat exchange sub-system that is used to vaporize a secondary coolant. In another embodiment, a nuclear reactor system is disclosed in which the reactor core is located below ground and all penetrations into the reactor pressure vessel are located above ground.
052271269	abstract	The internal structure comprises a bed (5) supporting the core (3) of the reactor and supplying liquid metal to the core, plating (6) resting on the bottom of the main vessel (1) of the reactor and an internal vessel (8) separating the hot collector (12) from the cold collector (13) of the liquid metal. The internal vessel (8) is directly fixed to the upper part of the bed (5) which rests on the plating (6) through the medium of slidable bearing means (21), (22). The bed (5) is connected to means (18) for supplying cooling liquid metal in a zone located at its periphery and outside the internal vessel (8) and the plating (6). Assemblies (31) providing a lateral neutronic protection are fixed to the bed (5) at the periphery of the fuel core (3).
	description	This U.S. nonprovisional application is a divisional under 35 U.S.C. §121 of U.S. application Ser. No. 11/024,952, filed Dec. 30, 2004, now U.S. Pat. No. 8,023,609 the disclosure of which is hereby incorporated herein in its entirety by reference. The present invention relates to an apparatus and methods for eliminating or substantially inhibiting electrostatic deposition of charged particles from the coolant onto the surface of an inlet-mixer of a jet pump forming part of a water recirculation system in a boiling water nuclear reactor, and for inhibiting stress corrosion cracking of the metallic parts. This invention particularly relates to an insulating barrier coating that eliminates or substantially inhibits the interaction between the conductive metal housing of the inlet-mixer of the jet pump assembly and the ionic particles in the fluid. In a boiling water nuclear reactor, an annular space is defined between the core shroud and the reactor pressure vessel wall. Jet pumps are located in the annular space for recirculating coolant through the reactor. The recirculation system circulates the cooling medium around the nuclear reactor core. Jet pumps, which contain no moving parts, provide an internal circulation path for the core coolant flow. Typically, a substantial number of jet pumps, for example, on the order of sixteen to twenty-four, are installed in this annular space. Each jet pump assembly consists of a riser assembly, a riser brace, two inlet-mixer assemblies, and two diffuser assemblies. The inlet-mixer includes a nozzle and a suction inlet. The nozzle may have one orifice or five orifices, depending on the jet pump design. The top of the inlet-mixer is mechanically clamped to the top of the riser transition piece, while the exit end of the inlet-mixer fits into a slip joint with the top of the diffuser. The inlet-mixer is a removable component. A recirculation pump, external to the reactor vessel, pulls suction from the downward flow of coolant in the annular space. The coolant is pumped to a higher pressure, and is distributed through a manifold to the jet pumps, where the coolant flows in an upward direction through the risers. The coolant splits in the transition piece and changes direction. It is then accelerated in a downward direction through the nozzles and into a mixer section of the jet pump. The nozzles cause a high velocity coolant flow that is approximately one third of the core flow and discharges into the inlet-mixers. Momentum causes surrounding water in the downcomer region of the annulus to also enter the mixer section where it mixes with the outflow from the nozzles for flow through the mixer section and diffuser. This combined flow discharges into the lower core plenum. The coolant then flows upward between the control rod drive guide tubes and is distributed for flow along individual fuel rods inside the fuel channels. Over time, contaminants tend to accumulate on the inside surface of the inlet-mixers including the jet pump nozzles, forming a layer of “crud.” There is also potential for stress corrosion cracking along these surfaces. The build-up of “crud” is attributed, at least in part, to charged particles suspended in the coolant which interact with the metallic inner surface of the inlet-mixer inducing a triboelectrostatic charge on the surface. This charge creates an electrostatic potential that attracts the suspended particles in the fluid to the metallic surface where they form a layer of particle contaminants. The greatest deposition of “crud” tends to be observed in areas that experience a high velocity flow rate. The accumulation of the layer of “crud” will tend to degrade the performance of the recirculation system. If the accumulation is excessive, this degradation will affect the efficiency of the plant because the recirculation pumps must be run at a higher speed to maintain core flow. Degradation of jet pump performance can also result in extreme jet pump vibration and damage to jet pump components. Eventually, the inlet-mixer must be mechanically cleaned or replaced during regular maintenance and refueling outages. This process is expensive and time consuming. Consequently, it is important that the accumulation of this layer of “crud” be suppressed or substantially eliminated in order to preserve a clear flow path and maintain the performance of the recirculation system. In the past, cleaning processes have been proposed that remove the “crud” layer from the inside surface of the inlet-mixer. These processes require removal of the inlet-mixer from the reactor for cleaning in the fuel pool. This is typically accomplished at regular scheduled shutdowns of the reactor, at which times the necessary maintenance is performed. A process using an electrical circuit has also been proposed for reducing the electrostatic deposition of charged particles on the inlet-mixer surfaces that are exposed to the free stream electrical potential in U.S. Pat. No. 5,444,747. This process employs a DC circuit with an active element feedback loop that adjusts the surface potential of the inlet-mixer to minimize the net flux to the inner conducting surface of the parts and thereby reduces particulate deposition. Implementation of this process, however, requires significant attention and maintenance and adds to the overall complexity of the recirculation system. Accordingly, there remains a need for apparatus and methods of protecting the inlet-mixers of the jet pumps from contaminant build-up. Furthermore, there remains a need for a solution to the problem of “crud” build-up which gradually degrades their performance and requires the need for periodically cleaning and maintaining the jet pump. An exemplary embodiment of the invention provides a coating on the inlet-mixer surfaces to reduce the electrostatic potential between the ionic fluid flow and such surfaces and thereby suppress or eliminate the build-up of crud. By reducing the electrostatic potential, the coating inhibits or reduces the formation of a particulate layer on the coated surfaces. Furthermore, the insulative coating tends to reduce the susceptibility of the coated inlet-mixer surfaces to stress corrosion cracking by lowering the electrochemical corrosion potential (ECP). To achieve these improvements, the interior surfaces of the inlet-mixers are provided with a coating which reduces or eliminates the build-up of charged particles on those surfaces. Particularly, the interior surfaces of each inlet-mixer are coated with a dielectric material that will tend to insulate the surfaces of these parts electrically from the fluid flow. This insulating layer will tend to suppress the development of an electrostatic potential typically resulting from triboelectrostatic charge induced on the conductive inner surfaces of the inlet-mixer. By suppressing the development of an electrostatic potential, the insulating layer will suppress the potential for interaction between the surface and charged particles suspended in the water. Thus, the coating tends to suppress or eliminate electrochemical interaction between the conductive housing surfaces and the ionic particles in the coolant. Because the charged particles are not attracted to the dielectric-coated surface to the degree that they are attracted to an uncoated conductive surface, the potential crud-forming or contaminating particles tend to pass through the inlet-mixer without being deposited on the interior surfaces of the inlet-mixer. The dielectric coating, therefore, reduces or eliminates the need for costly cleaning and maintenance of the jet pump and maintains the flow path clear of these potential contaminants. The dielectric coating electrochemically isolates the conductive surfaces from the reactor water and tends to retard diffusion of oxygen from the reactor water to the metal surfaces. These effects tend to reduce susceptibility to stress corrosion cracking of the metallic parts. The main purpose of this disclosure is to increase the performance and lifetime of the dielectric coating applied to components used in light water reactors such as Boiling Water Reactors (BWR), Pressurized Water Reactors (PWR), CANDU reactors, etc., such as jet pump nozzles/inlet mixers to reduce the oxide fouling on high flow surfaces. It is proposed to apply a dual coat; for example first to apply a thin layer of Ta2O5, or ZrO2, or other dielectric coating followed by another layer of TiO2 or other dielectric coating. This novel treatment will allow for a more electrically resistant coat in addition to a more adherent coat. For example, it has been shown that a Ta2O5 coating provides an excellent adherence to various substrates. In addition, the TiO2 layer will have a greater adherence to the Ta2O5 layer compared to its adherence to the base material of interest. This dual-coat approach may be applied to replacement components such as core spray piping to improve resistance to stress corrosion cracking and other forms of corrosion, such as erosion corrosion. As used herein, erosion corrosion refers to corrosion of a metal that is caused or accelerated by the relative motion of the environment and the metal surface and is typically characterized by surface features with a directional pattern which are a direct result of the flowing media. Other factors such as turbulence, cavitation, impingement or galvanic effects can add to the severity of the corrosion. Other potential applications are impellers, flow elements, valves, other applications which are exposed to high flow water and are susceptible to fouling from the charged ions in the fluid. The coating is preferably an insulating metal oxide coating, e.g., a coating formed of TiO2 or Ta2O5, although other materials as described below may also be employed as either of the coating layers. The coating is applied by placing the part, such as a nozzle assembly, in a heated vacuum reactor vessel. Once the desired reaction conditions have been achieved, one or more suitable chemical precursors, e.g., Ti(OC2H5)4 or Ta(OC2H5)5, are introduced into the system. These precursor compounds thermally decompose on the surface of the part being processed, producing the dielectric coating and releasing several byproduct gases. The product is then cooled and ready for installation in the nuclear reactor. In an exemplary embodiment according to the present invention, there is provided a multi-layer dielectric coating for reducing or eliminating deposition of charged particulates on the wetted surfaces of the flow passages of a jet pump in a boiling water reactor. In another exemplary embodiment according to the present invention, there is provided a method for forming a multi-layer dielectric coating for reducing or eliminating deposition of charged particulates on the wetted surfaces of the flow passages of a jet pump in a boiling water reactor. These drawings have been provided to assist in the understanding of the exemplary embodiments of the invention as described in more detail below and should not be construed as unduly limiting the invention. In particular, the relative spacing, positioning, sizing and dimensions of the various elements illustrated in the drawings are not drawn to scale and may have been exaggerated, reduced or otherwise modified for the purpose of improved clarity. Those of ordinary skill in the art will also appreciate that a range of alternative configurations have been omitted simply to improve the clarity and reduce the number of drawings. As illustrated in FIG. 1, a conventional reactor will include a reactor pressure vessel 10 that includes a reactor pressure vessel wall 12 and an inner core shroud 14 defining a generally annular space 16 therebetween that contains coolant. As in a typical BWR, a plurality of jet pumps, one being generally designated 18, are disposed at circumferential spaced positions surrounding the pressure vessel in the annular space 16 defined between the pressure vessel wall 12 and the core shroud 14. Each jet pump 18 typically comprises an inlet riser 20, a transition piece 28 adjacent the upper end of the inlet riser 20, a pair of elbows 22, inlet-mixers 23, each including nozzles 24 and mixing sections 25, and diffusers 26. Hold down assemblies adjacent the top of the jet pump 18, together with a number of braces and restraining assemblies maintain each jet pump 18 in a substantially fixed position in the annular space 16 between the core shroud 14 and pressure vessel wall 12. A thermal sleeve 32 penetrates the pressure vessel wall 12 and is welded at its juncture with an inlet elbow with the opposite end of the inlet elbow being secured to the lower end of the inlet riser 20. It will be appreciated that the foregoing-described jet pump 18 is conventional in construction. Thus, coolant enters the thermal sleeve 32 and flows through the elbow, upwardly in the inlet riser 20, through the inlet elbows 22 through nozzles 24 for flow in a downward direction through the mixing sections 25, the diffusers 26 and into a plenum 40 for upward flow through the reactor core. During conventional operation, the jet pump nozzles 24 will induce a suction flow of coolant from the annular space 16 into the mixing section 25 which mixes with the coolant flow through the jet pump nozzles 24. Illustrated more particularly to FIG. 2 is a portion of a jet pump 18 having an inlet elbow 22 adjacent five nozzles 24. The nozzles 24 are supported above the mixing sections 25 and, in combination with the mixing sections define a generally annular suction flow passage 29 between the nozzles 24 and an inlet to the mixing section 25. It will be appreciated that the mixing section 25 is typically a generally cylindrical pipe which terminates at its lower end in an inlet to the diffuser 26. Consequently, the flow of coolant through the nozzles 24 induces a suction flow of coolant through the annular spacer 16 for flow into the mixing section 25. These combined nozzle and suction flows pass through the mixing section 25 and diffuser 26 and into plenum 40. Illustrated in FIG. 3 are two of the nozzles 24. It will be appreciated that the interior passages through nozzles 24 are generally conical or frusto-conical in shape with the diameter decreasing along the path of the fluid flow, thereby increasing the flow velocity into mixing section 25. The increased velocity induces additional fluid to flow into the sleeve through the annular opening 29 between the nozzles 24 and the mixer sleeve inlet as indicated by the arrows in FIG. 2. In accordance with a preferred embodiment of the present invention, the inlet-mixer is provided with a coating that inhibits or eliminates “crud” build-up. To accomplish this, the inlet-mixer 23 is placed in a chemical vapor deposition (“CVD”) reactor. The reactor is a heated vacuum vessel that is sufficiently large to house the part being coated. The vessel is then evacuated and the pressure is dropped to approximately 20 mTorr. Heat is applied to raise the temperature of the vessel and the part being coated to a reaction temperature sufficient to decompose an organometallic source gas, typically within a range of about 400°-500° C. and preferably about 450° C. When the reactor vessel reaches the reaction temperature and pressure, chemical precursors, such as one or more organometallic precursor or source gases are injected into the reactor chamber. The precursor gas(es) impinge on the surface of the heated inlet-mixer part and thermally decompose to form a metal oxide insulator coating corresponding to the metallic portion of the source gas(es) and byproduct gases. For example, source gases such as Ti(OC2H5)4 and Ta(OC2H5)5 are useful for forming the corresponding oxides TiO2 and Ta2O5. Depending on the selection of the precursor gas(es), this method may be used to deposit layers including such metallic oxides as TiO2, Ta2O5, SiO2, Al2O3, ZrO2, Nb2O5, SrBi2, Ta2O3, Y2O3, HfO2, BaO, SrO, SrTiO3, PbTiO3, and PbZrO3, and byproduct gases that are evacuated from the reactor vessel. The deposition process is maintained for a period sufficient to achieve a base metal oxide coating of the desired thickness, typically between about 0.1 and 2 μm, after which the gas flow of the first precursor gas(es) is terminated. The reactor vessel may then be purged with an inert gas or gases to remove the initial precursor gas(es) while generally maintaining the reactor pressure and temperature. After the majority of the initial precursor gas(es) have been removed from the reactor, a different organometallic precursor or source gas or mixture of such gases is introduced into the reactor chamber. The precursor gas(es) impinge on the surface of the first metal oxide insulator layer formed on the heated inlet-mixer part and thermally decompose to form a second metal oxide insulator coating corresponding to the metallic portion of the source gas(es) and byproduct gases. When a sufficiently thick coating is achieved, e.g., within a range of about 0.5 to about 3.0 μm, heating is terminated and the reactor vessel and the coated part are cooled. Once the temperature is sufficiently low, the vacuum is released and the reactor chamber opened to allow removal of the coated part. This technique may be used to form the coating 31 as illustrated in FIGS. 2 and 3 along the interior wall surfaces of the inlet-mixer 23. The multi-layer coating process for the high flow surfaces of the jet pump or other parts exposed to such high flow conditions provides for the application of an initial or base dielectric coating of relatively smaller thickness (e.g., about 0.1 to about 0.5 μm) which exhibits improved adherence to the base material and provides a clean surface for the application of the second or outer dielectric coating. The second or outer dielectric coating may then be selected to provide sufficient adherence to the initial or base dielectric coating while providing improved resistance to the anticipated operating environment. As illustrated in FIGS. 4A-4C, a part fabricated from a conductive base material 100 and having one or more wetted surfaces 100a, 100b, that may be exposed to high velocity fluid flow during operation. Depending on the intended application for the part, one or both (not shown) of the surfaces may be coated with a protective dielectric coating. As illustrated in FIG. 4B, surface 100a is initially coated with a first or base dielectric layer or coating 102, the coating material and application method being selected to provide improved adhesion between the coating and the surface. As illustrated in FIG. 4C, after forming the base dielectric layer 102, a second dielectric layer 104 is applied to the base dielectric layer to form the outer surface of the coated part. The coating material and the application method used for the second dielectric layer are typically selected to provide adequate adhesion to the base layer to prevent delamination while also providing improved corrosion and/or erosion corrosion resistance in the anticipated operating environment relative to that achieved by the base layer material. A suitable initial or base coating material is the tantalum oxide material tantala (Ta2O5) that may be used in combination with a second or outer coating layer of the titanium oxide material titania (TiO2). Although described above as a simple dual-layer coating, those of ordinary skill will appreciate that, depending on the materials and application methods, each of the coatings illustrated in FIGS. 4B-4C may actually comprise a series of thinner sublayers of substantially uniform composition or a series of sublayers that exhibit a predetermined range of compositions in a direction substantially normal to the coated surface 100a. Similarly, one or more additional layers (not shown) may be formed between the base layer 102 and the outer layer 104 to improve the structural integrity of the composite coating or improve other properties of the coating with respect to, for example, chemical resistance. As noted above, a wide range of metal oxide dielectrics may be used to form the base and outer coatings, including, for example, zirconia, silica, alumina, or other metal oxide that exhibits sufficient chemical and mechanical resistance to anticipated operating environment. The CVD process as described above, or another gas phase deposition process such as Atomic Layer Deposition (ALD), are generally suitable for forming a conformal surface coating on a complex three-dimensional surface. Depending on the size and configuration of the surface(s) being coated, physical vapor deposition (PVD), plasma enhanced physical vapor deposition (PEPVD) and radio frequency (RF) sputtering may also be suitable for forming layers including one or more of the oxides noted above. Similarly, depending on the configuration of the part and the accessibility of the surface to be coated, other methods of applying protective material layer could also be utilized to form the base coating and/or the outer coating. These methods may include electric arc spraying (EAS), plasma spray coating processes, also referred to as plasma arc spraying (PAS) processes, which can be conducted at atmospheric pressure (APS), under a vacuum (VPS), or in the presence of a low pressure inert gas (LPPS), high velocity oxy-fuel (HVOF) processes and/or other conventional coating processes that are capable of producing the appropriate dielectric layers of sufficient thickness and uniformity. The initial dielectric coating, such as Ta2O5, allows for increased electrical resistance against fouling and adherence of the outer coating to the part, thereby suppressing delamination. The outer coating, such as TiO2, may then be selected to provide improved resistance to the jet pump environment while exhibiting good adherence to the initial or intermediate coatings and to reduce or eliminate surface fouling. This same dual-coat approach may be applied to replacement components such as core spray piping to improve resistance to stress corrosion cracking. Other parts that could benefit from a dielectric coating include impellers, flow elements, valves, other application which are exposed to high flow water and susceptible to fouling from the charged ions in the fluid. It is anticipated that Ta2O5 will be suitable for forming an initial coating that will provide both sufficient electrical resistance and sufficient adhesion on a range of base metals, such as stainless steel, used in fabricating the parts. It is also anticipated that TiO2 will be suitable for forming an outer layer on a Ta2O5 base coating that will exhibit both sufficient adherence to the underlying Ta2O5 layer while improving the corrosion resistance in a BWR environment over that exhibited by Ta2O5. It is anticipated that the multi-layer Ta2O5/TiO2 dielectric coating will outperform a single dielectric coat of Ta2O5 or TiO2 having the same thickness in BWR applications, including jet pump surfaces. It will be appreciated by those of ordinary skill in the art that the coating process as described above may incorporate additional steps such as a cleaning or etching step to prepare the surface of the part being coated to receive the base dielectric coating and improve the adhesion of the base layer. Similarly, although the process as generally been described as a dual layer process, it will be appreciated that one or more intermediate layers may be provided to allow for more precise control of the characteristics of the coating. In addition, additional surface treatments such as nitridation or other surface modification processes may be utilized to increase the resistance of the outer layer to the anticipated operating environment for the coated part. While the invention has been described in connection with what are presently considered to be practical and representative exemplary embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.
048658014	description	DETAILED DESCRIPTION OF THE INVENTION FIG. 1 depicts the mechanical area immediately above the under-vessel maintenance area, which mechanical area is shown generally as (10), of a power generating nuclear reactor of the boiling water type. Shown in this mechanical area (10) are a number of control rod drives (12) and the assembly of the control rod drive housing support members (14). When maintenance or replacement work is done during a reactor shutdown, the control rod drive housing support members (14), also referred to as the shoot-out steel assembly, is normally disassembled and removed as a first step. The exposure to radiation emanating from the flange assemblies (16) of the control rod drives and from the components above these assemblies, limits the work time available for such maintenance work unless such radiation can be effectively shielded. FIG. 2 shows a control rod drive (12) in the area of the control rod drive flange assembly (16). The control rod drive housing (18) terminates at its lower end in a control rod drive housing flange (20), which mates with a control rod drive flange (22) to form the flange assembly (16). These flanges are secured together by some form of bolting means (24) as illustrated by the eight capscrews in FIG. 2. Below the control rod drive flange (22), the connections for a position indicating probe are located, as shown by the probe housing (26), the probe connector plug (28) and the probe cable (30). After the control rods have been raised and locked in their fully inserted positions within the reactor vessel, these components are normally disconnected in routine maintenance work, and are inspected and periodically replaced as necessary. Many design considerations were applied in the design of the shielding device of the present invention, particularly the design of the preferred embodiment of the present invention. These design considerations include: 1. The primary purpose of the shielding device should be to reduce the radiation doses to under-vessel maintenance personnel to levels as low as reasonably achievable. 2. The shielding device should place the maximum practical amount of shielding material between the radiation emitted and the worker. 3. The shielding device should be reasonably portable. That is, it must be light enough in weight and have a suitable shape to permit it to be carried by under-vessel workers wearing anti-contamination clothing, respirators and heavy gloves while they walk, bend and crouch. 4. Ideally, each portion of the shielding device should not weigh more than 50 to 65 pounds. 5. The shielding device should be mechanically designed so that it is capable of supporting all of its own weight structures and attachments without reliance on external sources of support and without any deformation or loss of function. 6. The shielding device should be installed and removed easily by under-vessel workers wearing anti-contamination clothing, respirators and heavy gloves. 7. The shielding device should feature installation and removal mechanisms that are easily accessible to the under-vessel workers, and that do not require access to the top or the side of the device. In fact, all mechanisms of the device should be accessible from the bottom of the device. 8. The shielding device should be quickly and easily installed. Hence, the installation of the device should be completely indifferent to the orientation of the device around the flange assembly. 9. While the shielding device should minimize the unshielded gamma radiation from the flange assembly, it should also allow the maximum head room to under-vessel workers. The shielding device should, therefore, be positioned close to the flange assembly. 10. The shielding device should not interfere with any other under-vessel components nor the flange assembly of any other control rod drive. Therefore, the outer diameter of the shielding device should be made as close as possible to the outer diameter of the flange assembly, and all exterior surfaces should be smooth. 11. The shielding device, when secured to the flange assembly or while being installed or removed, should not cause any harm to the flange assembly, or its electrical or mechanical components. Therefore, the shielding device should not impose any loads upon, and should preferably not even be in contact with, the hydraulic actuation lines or the position indicating probe components of each control rod drive. 12. The shielding device and any individual members thereof should not impose any safety hazards to under-vessel workers. Therefore, the method of attaching each component of a shielding device to the flange assembly should be independent, secure, stable and positive. The shielding device should remain secured to the flange assembly in the event of any accidental impact it might receive in the course of any under-vessel maintenance. Removal of the shielding device should require a series of deliberate actions that would not be likely to be performed without the intention of removing the device, or any of its components, from its secured position. 13. The shielding device should be able to function and be installed and removed independent of the presence of a position indicating probe cable. In its preferred embodiment, the shielding device should not require disconnection of the position indicating probe cables, but should allow such disconnection and reconnection without complete removal of the shielding device. 14. The shielding device, when installed, should allow ample access to the probe cable and connector plug, as well as other electrical and mechanical components inside the flange assembly. Therefore, the preferred embodiment of the shielding device should feature an access door large enough to permit all electrical, mechanical and maintenance functions up to, but not including, breach of the control rod drive flange. Included, without limitation, within such functions, would be removal of the position indicating probe housing and uncoupling of the control rod drive itself, without substantially compromising the radiation shielding performance or the mechanical integrity of the shielding device. 15. The shielding device should be designed to limit its own potential for radioactive contamination as well as help control its spread. The shielding device should provide passive protection of the flange assembly to which it is attached from any radioactive contaminants which might be released by the breach of an adjacent control rod drive flange. 16. The shielding device should not become a source of radiation itself. Construction of the device and its independent members should be water-tight and should be of materials which resist corrosion and which will not develop cracks or crevices. 17. If lead is employed as the shielding material, because of its superior shielding performance, it should be completely encapsulated within a shell to avoid any potential for exposure of the under-vessel workers to lead. 18. The shielding device should be designed for use while the reactor is in the Shutdown or Refuel state. 19. The shielding device should be serviceable after repeated decontamination procedures and during and after repeated exposure to the following boundary conditions: Temperature: 212.degree. F. (Hot Decontamination) PA1 Humidity: 100% 20. The shielding device should be of durable construction and should withstand such abuse as dropping and throwing without deformation or loss of function. Exposed mechanisms should be protected, as by a bumper. 21. The shielding device should be designed so that any detachable parts or components which are removed are completely interchangeable with those of other shield devices. 22. The shielding device should be designed and fabricated so that, while installed, it resists the accumulation of fluids that could splash onto workers during its removal. 23. The shielding device should not require any permanent modification of existing under-vessel equipment for the purpose of attachment. In the simplest form of the present invention shielding material, in the form of sheets of lead plate, was hung in a form of chain framework suspended from the control rod drive housing support members. The individual sheets were about one-quarter inch in thickness and measured about two feet by four feet. However, in testing this embodiment, when the third sheet of lead was positioned within the framework, the assembled weight became too great for the framework and the hanging means failed. While this embodiment demonstrated the shielding function and while an array of such assemblies was able to provide substantially complete overhead coverage, most of the other design criteria set out above were not met. In particular, the support members could not be removed and access to the control rod drive was limited and difficult. Further, because such an assembly hung below the support members, head room in the under vessel maintenance area was severely, if not critically, limited. Another simplistic embodiment of the present invention, consists of lead disks approximately one to one and one-quarter inch thick and ten to eleven inches in diameter. These crude disks were suspended from the top surface of each flange assembly by a pair of bent carbon steel rods. This crude design, lacking most of the features of the preferred embodiment, was sufficient to allow testing to demonstrate the feasibility and the shielding potential of this type of under-vessel shielding. In such a test, an average dose reduction of roughly 60% was achieved immediately below a 3.times.3 array of flange assemblies fitted with such disks. Since the intensity of radiation diminishes with the square of the distance, the highest level of exposure would be expected to be encountered immediately below the control rod drive flanges. Dosimeter equipment is typically worn on the heads of under-vessel maintenance workers for this reason. A slightly more sophisticated embodiment of the present invention employs a disk which is 95/8 inches in diameter and 11/4 inches in thickness. This disk was first suspended from the top surface of the flange assembly by triangular gusset pieces welded to the tops of a pair of carbon steel bars. The spring action of the steel bars is relied upon to initially locate the triangular pieces on the top of each flange assembly. Once the disk is located in this position, carbon steel rods are inserted through the lead disk, through pipe tracks welded to the inner surface of the suspension bars. The tops of these rods are positioned into the sockets of two opposite capscrews on the undersurface of the flange assembly, and the rods are then locked in that position. The design also features a slot in the lead disk for the probe cable of the control rod drive and this slot can be closed after installation by a lead door mounted to the disk with a hinge. While the design is easy and rapid to install, removal presents a more difficult problem because the steel bars are required to be pulled apart, a difficult maneuver in view of the limited access space between the flange assemblies. Further, although the design is fairly stable it can be dislodged from the flange assembly by a sharp blow. Several other desirable design criteria are not met by the design. Another embodiment is more similar in form to the preferred embodiment of the present invention. Actually three slightly different versions of the same embodiment were prepared and tested. In each case, the shielding device is divided into two half shields and employs shells of stainless steel to enclose the flange assembly and stainless steel jacketing to completely enclose the lead shielding material. Only the method of attachment differs in the three versions. The first version attaches with a first contact point which is an inward-facing lip on the top of the stainless-steel shell, and this lip rests on the top of the flange assembly. A second contact employs a shaft driven arcuate-shaped flat retaining plate which is positioned between the underside of the flange and the heads of one or more of the capscrews. This plate is held in place by a hasp lock on the lower edge of the shell. In addition, the first version employs a pair of latching cross-ties on lower portion of each shell to allow the two half shields to lend stability to each other. This method of mounting is not completely secure and the unit could swing, pivoting on the lower edge of the flange assembly, far enough to remove the first contact point from the top of the flange assembly. While this would not present a problem once both units were positioned and cross-connected, it requires a worker to hold one half-shield in place while positioning another. The same problem re-occurs in removal of the shields. The second version of this embodiment employs a third contact point, an inward facing wall on the interior surface of the stainless-steel shell. This wall acts as a spacer and prevents the unit from swinging. However, the attachment of the unit is still too tight and although serviceable, tended to rattle. The final version of this embodiment was similar in every respect except that the second contact point was changed from the flat plate to a wedge shape. The wedge was not simply positioned between the capscrew heads and the flange, but was tightened into that position with a threaded shaft and a crank. This method of attachment allowed for the variations in dimension from flange to flange of the various control rods and the fabrication differences from shielding member to shielding member and enabled a secure attachment which could not be disengaged. In the following description of the preferred embodiment, it should be remembered that the previously described embodiments all served the primary function, shielding under-vessel workers, more or less as well as the preferred embodiment. The preferred embodiment, however, performs this shielding function and more completely meets the other expressed design criteria set out above. In the preferred embodiment, the shielding device of the present invention is comprised of two half shields or shielding members. One of these shielding members is shown as (32) in FIG. 3. This shielding member (32) is shown in a view which is partly broken away to allow view of the shielding material (34) which is shaded in the figure. In the complete shielding member (32), these shaded areas of shielding material (34) would be completely enclosed. The shielding member consists generally of a cylindrical outer wall (36), a first cylindrical inner wall (38), an outer bottom wall (40), an inner bottom wall (42), and an annular upper interior wall (43). These walls, together with the walls covering the shielding material (34) which are shown, surround and enclose the shielding material (34), in the form of a partial cylindrical chamber (44) and a partial annular chamber (46). In the preferred embodiment, the shielding member is provided with attachment means comprising three points of contact. The first point of contact (60) is comprised by an inward facing rim or lip which is intended to rest on the top surface of the control rod drive housing flange (20). The second point of contact (62) comprises a wedge-shaped arcuate member (64) which can be vertically adjusted by some means such as the threaded drive shaft (66) and a cranking means (68). When properly positioned, said wedge-shaped arcuate member (64) can be held in position by securing the cranking means (68) with locking means (70). As mentioned previously, this adjustable wedge-shaped arcuate member (64) allows each shielding member (32) to be securely and positively attached to any flange assembly (16) of any control rod drive (12) despite small differences in dimension from one flange assembly to another and from one shielding member to another shielding member. The third point of contact (72) consists of an annular interior wall (74) which extends inward to contact the control rod drive flange (22) when the shielding member (32) is properly positioned. In the preferred embodiment, this annular interior wall (74) is actually a continuation of the annular upper interior wall (43). This is primarily a matter of convenience in construction, however, and the annular interior wall (74) could be positioned equally advantageously at any position on the interior of the outer wall (36) or the first cylindrical inner wall (38) so long as it would be in contact with the control rod drive flange assembly (16). Further, there is no requirement that the third point of contact (72) be a continous wall, so long as satisfactory supportive contact is made. Integral to the shielding member (32) of FIG. 3, but detachable and detached from the shielding member (32) shown in FIG. 3, is an access door (48) shown in FIG. 4. This access door (48) engages in intimate contact as part of the shielding member (32) completing the partial annular chamber (46) of the shielding member (32). With continued reference to FIG. 4, the access door comprises a portion of the partial annular chamber (46), surrounding an opening (50) which would be central to the complete annulus. This opening is defined by the second cylindrical inner wall (52) which joins the outer bottom wall (40) and the inner bottom wall (42). Side walls (54) are necessitated by the removable nature of the access door (48) and serve to enclose the shielding material (34) as are similar walls of the mating surfaces which are not shown in the cut away view of FIG. 3. In the preferred embodiment, the access door (48) is additionally provided with a lifting handle (76) which, when the access door (48) is attached, acts as a lifting handle for the entire shielding member. It should be apparent to one skilled in the art that such a handle could be located anywhere on the shielding member (32), but placement on the access door (48), which should have some form of handling means to ease in removal, is a matter of convenience. The present location of the lifting handle (76) also allows it to act as a bumper, to help protect the exposed mechanisms on the bottom of the shielding member (32) from inadvertent impacts. Also, the access door (48) as shown is roughly rectangular and when the access doors of mating shielding members are removed, the opening would be approximately square. One skilled in the art will recognize that such geometries are not necessary to the usefulness of the shielding device. Such doors could easily be triangular, yielding the same approximate square opening when mated, or semi-circular, yielding a circular opening. The geometry of the access door (48) is, therefore, a matter of choice. The shielding member (32) together with its integral access door (48) is shown in position on a control rod drive flange assembly (16) in FIG. 5. The access door (48) is held in position by some mechanism such as the deadbolts (56) shown isolated in FIG. 4 and engaged in FIG. 5, engaging receptacles (58) of the shielding member (32). As is shown clearly in FIG. 5, the shielding member (32) or half-shield, encloses one half of the lower terminus of a control rod drive. A second shielding member in mating contiguous engagement would enclose the other half. It should be obvious to one skilled in the art that the choice of two half shields is a matter of convenience, and the shielding device could be divided into almost any number. As with any shielding device, the more shielding material which can be employed, the higher the amount of shielding which will be obtained. However, the need for the shielding device to be handled limits the amount each member of the shielding device can weigh. At the same time, the time required for installation and removal is a direct function of the number of members into which the shielding device is divided, and the added installation and removal time also represents additional exposure time for the worker. In fact, the installation and removal time, employing the shielding device of the present invention, is a period during which some of the highest exposure rates are incurred. Therefore, an unnecessary number of shielding members per shielding device can compromise the purpose of the device even though increased shielding will result. Two half-shields have been employed in the preferred embodiment in an attempt to position the maximum shielding material in the shortest period of time. The installation procedure of the preferred embodiment of each member of the shielding device consists of only four simple steps. First, the first contact point (60) shown in FIG. 3, is positioned on the top of the control rod drive housing flange (20) shown in FIG. 2. Second, while keeping the first point of contact positioned on top of the housing flange (20), the shielding member is swung in towards the flange assembly (16) until the third point of contact (72) shown in FIG. 3, is in contact with the control rod drive flange (22) shown in FIG. 2. Third, the second point of contact (62) is positioned. This is done by raising the wedge-shaped arcuate member (64) using the cranking means (68) as shown in FIG. 3, or another mechanism, such as a spring, until it is firmly positioned between the bolting means (24) and the control rod drive flange (22) as shown in FIG. 2. Finally, once the wedge-shaped member (64) is firmly positioned, the cranking means (68) of the threaded drive shaft (66) is secured in that position with locking means (70). Installation of the mating shielding member follows the same procedure. Lead has previously been mentioned as the shielding material and is employed in the preferred embodiment because of its cost and high efficiency as a shielding material. Various alternative materials could also be employed and examples of these are: iron or iron-bearing allows, such as stainless steel; depleted uranium; and concrete, especially high density concrete. In fact, any material having a suitable density could be employed. Of course, if stainless steel were employed as the shielding material, there would be no requirement to completely encase it within another non-corrosive shell. In fact, the shell of the preferred embodiment could be manufactured as one or more stainless steel castings. No. 316 Stainless has been used in the preferred embodiment for a number of reasons including but not limited to its non-corrosive nature, structural properties, shielding potential, workability durability, cost and availability. Other grades of stainless steel could easily be employed as well as aluminum, titanium, and high-impact plastics as well as painted or plastic coated corrodible metals. In choosing a material for use as a housing material, one must review the design criteria set out above and choose the material which will best satisfy those criteria which are believed to be the most important. It should also be apparent to one skilled in the art that a collar of shielding material could be placed as a jacket surrounding the control rod drive flange (22) and attached by using longer cap screws. Such a construction would be of a more permanent nature and would interfere with the support members (14) as presently designed. However, such a design would meet most of the design criteria above and is certainly within the contemplation of the present invention. Provision of such collars as permanent attachments in the nature of a retrofit or redesign of the present control rod drive flange itself would require a re-calculation of the allowable weight loads and redesign of the structural members, but would reduce exposure times by not requiring installation and removal. The effectiveness of the shielding devices of the present invention was recently demonstrated in a large boiling water reactor. The tests and measurements taken were intended to investigate the ability of the shielding devices to reduce the effective under-vessel dose rates while subject to conditions normally experienced during a typical refueling outage. Shielding devices were installed on each of the control rod drive flanges, and the under-vessel outage work was performed in an otherwise normal manner. The under-vessel dose rates before and after the installation of the shielding devices, the manpower and additional dose required to install and remove the shielding devices, and the actual doses received by the under-vessel workers were all measured. This information was used together with projections based upon previous experience at the plant to determine the net reduction in under-vessel man-rem expenditure that is attributable to the use of the shielding devices. The following table summarizes the results: ______________________________________ Reduction In Average Maximum Measurement Point Reduction Dose Rate ______________________________________ Head (6 ft. above floor) 72% 71% Waist (3 ft. above floor) 59% 64% Floor 52% 57% Reduction in Median Effective Worker Dose Rate (man-rem/man-hour) = 53% ______________________________________ Other features, advantages and specific embodiments of this invention will become readily apparent to those exercising ordinary skill in the art after reading the foregoing disclosures. These specific embodiments are within the scope of the claimed subject matter unless otherwise expressly indicated to the contrary. Moreover, while specific embodiments of this invention have been described in considerable detail, variations and modifications of these embodiments can be effected without departing from the spirit and scope of this invention as disclosed and claimed.
	summary
043137946	summary	BACKGROUND OF THE INVENTION 1. Field of the Invention Broadly, the present invention relates to a self-actuating and self-locking flow cutoff valve. It particularly relates to use of such a valve in a nuclear reactor of the type which utilizes a plurality of fluid supported absorber elements to provide for the safe shutdown of the reactor. 2. Prior Art There are numerous applications wherein there is a need for a self-actuating, self-locking flow cutoff valve. The need is particularly great in the case of nuclear reactors of the type which utilize a plurality of fluid supported neutron absorber elements to ensure the capability for a safe shutdown of the reactor. More particularly, heretofore nuclear reactors were typically shut down by control rods which were introduced through the top of the core and raised from or lowered into the core by mechanical means such as a motor which operates via clutch gears or the like. In an emergency, the clutch would be disengaged and the control rods allowed to fall into the core to shut down the reactor. Such a system had certain disadvantages. Specifically, there is a possibility that a mechanical device such as the clutch could not be disengaged or that some fault may have occurred which would distort the passage through which the control rods have to pass causing them to bind and preventing full insertion of the rods into the core. In such instance, it would not be possible to shut down the reactor. Accordingly, considerable interest has been generated in the use of a plurality of fluid supported neutron absorbing elements which would fall under the influence of gravity into the core in the event of a loss of fluid flow. Thus the reactor could be shut down by the simple expedient of shutting off the flow and further, in the event of an unforeseen loss of fluid flow, the reactor also would be shut down automatically. U.S. Pat. No. 3,228,847 suggests a reactor control system which includes a control assembly for controlling neutronic flux. The control assembly comprises an inner tube extending from a nonactive region of the reactor into the active region, and an outer tube surrounding the inner tube and spaced therefrom. The outer tube has a closed end and the inner tube has an open end adjacent and spaced from the closed end of the outer tube. Neutron absorbing particles are positioned between the inner and outer tube for movement along the tube under the force of flow. The neutron absorbing particles are moved out of the active region of the reactor by fluid flow and fall back into the active region under the influence of gravity when the flow is shut off. U.S. Pat. No. 3,257,286 suggests a ball-type control for a nuclear reactor. A number of elongated conduits are positioned in the nuclear reactor so that the first section of the conduit is located within the core and an adjoining second section is located exteriorly of the core. Each conduit holds a number of individual bodies, each of which contains a high neutron absorption cross-section material. The movement of the neutron absorber bodies within the conduits is achieved by providing a source of pressurized fluid available to each end of the conduit for selectively positioning the neutron absorber bodies within the first and second sections of the conduit. It is stated that a fission reactor can be started up, shut down, or reactivity controlled during reactor operations by varying the location of the absorber bodies. U.S. Pat. No. 3,347,747 discloses a control organization and method for a nuclear reactor. The reactor is provided with a number of laterally spaced vertical passageways in the region of the core and distributed throughout the area thereof. The passageways include a lower portion which extends generally throughout the height of the core and an upper portion which extends above the core into the reactor vessel. Positioned within and confined in each passageway is a movable means which contains a poison and which is movable from a lower position within the region of the core to an upper position in the passageway, where it is generally above the core. The poison-containing means is moved by gravity to its lower position and is moved from its lower to its upper position by means of a fluid which is directed upward in the passageway. In U.S. Pat. No. 4,076,583 there is disclosed another control method for a nuclear reactor which comprises a plurality of elongated conduits extending through and above the core of a reactor. A plurality of neutron absorber elements are located within the conduit, and during normal operation form a stacked bed in the portion of the conduit extending above the core. That section of the conduit in which the stacked bed is formed is provided with a fluid bypass means, it having been found that such bypass means ensures the capability of reliably maintaining all of the absorber elements in the stacked bed and out of the core during normal operations and further minimizing the pressure drop of fluid flowing through the stacked bed during normal operation. While all of the foregoing suggested techniques appear to offer advantages over reliance solely on a control rod system, there is still room for improvement. More particularly, in all of these systems where gravity is relied upon to cause the absorber elements to move into the core, any residual fluid flow, even though it may be below the minimum for safe operation of the reactor, acts to retard the fall of the absorber elements. For example, in the event of a complete power failure, the inertia of a centrifugal pump would be sufficient to continue providing some flow after the loss of power and after the flow rate of fluid had dropped below the point at which the reactor should be shut down. Thus, clearly it would be advantageous to have a self-actuating flow cutoff valve in the fluid stream such that once the fluid flow dropped below a predetermined point, the valve would automatically close and substantially reduce the time required for the neutron absorbing elements to fall into the reactor core and safely shut it down. Further, in the event that there might be some erratic flow or surge of pressure or flow subsequent to it having declined below the safe level, such valve advantageously would be self-locking to prevent an inadvertent startup of the reactor by a resumption of fluid flow. SUMMARY OF THE INVENTION The present invention provides a flow cutoff valve which is self-actuating and once in a closed position is self-locking. The present invention is particularly applicable to a nuclear reactor of the type which utilizes a plurality of fluid supported absorber elements to provide for the safe shutdown of the reactor. Broadly, the invention comprises a substantially vertical elongated housing having an apertured plate located therein, the apertures providing for fluid flow from one end of the housing to the other. A substantially vertical elongated nozzle member also is located in and affixed to the housing. The nozzle member has an opening in its bottom end for receiving fluid and apertures adjacent the top end for discharging fluid, and two sealing means comnprising radially outwardly and downwardly extending sealing surfaces, one located above and the other below the apertures. The nozzle member is surrounded by the walls of an elongated flow cutoff sleeve having a fluid opening adjacent its upper end. The sleeve also includes two sealing means comprising radially inwardly and upwardly extending sealing surfaces affixed to it, one below the flow opening and one adjacent the lower end of the sleeve. The sleeve is movable from an upper open position wherein the nozzle apertures are substantially unobstructed to the flow of fluid therethrough and a closed position wherein the sleeve and nozzle sealing surfaces are mated and the mated sealing surfaces and the walls of the sleeve obstruct the flow of fluid through the apertures. In addition, the nozzle and sleeve sealing means cooperatively act together to provide for the exposure of a greater area for fluid pressure to exert a force in a downward direction than is exposed to fluid pressure to exert a force in an upward direction whereby once said valve is in a closed position, any increase in fluid pressure will act to maintain the valve in a closed position. The valve further includes a balance member located above and attached to the flow cutoff sleeve. The balance member contacts the apertured plate when the sleeve is in an open position and obstructs the flow of fluid through a predetermined flow area of the apertures in the apertured plate to produce a pressure drop across the apertured plate and balance member; the pressure drop being just sufficient to support the balance member and flow cutoff sleeve at a predetermined minimum fluid flow. Thus, when the fluid flow drops below a predetermined value, the pressure drop across the balance member will be insufficient to maintain the flow cutoff sleeve in an open position and it will move under the influence of gravity to a closed position. In one embodiment of the invention, the cutoff valve further includes a piston member extending upwardly from the top end of the nozzle member and into the flow cutoff sleeve a sufficient distance such that when the sleeve moves from an open to a closed position, the uppermost portion of the piston member moves past the flow opening in the flow cutoff sleeve and the fluid trapped therein provides a dampening force on the closure of the flow cutoff sleeve to prevent or minimize any hydraulic shock. In yet another embodiment of the invention, the valve further includes a mechanical means for moving the flow cutoff sleeve between an open and closed position. The various features of the novelty which characterize the invention are pointed out with particularity in the claims which form part of this specification. For a better understanding of the invention, its operating advantage and specific objects attained by its use, reference should be made to the accompanying drawings and descriptive matter in which are illustrated and described, respectively, certain preferred embodiments of the invention.
	abstract	A riser cone has a lower end sized to engage a cylindrical lower riser section of a nuclear reactor and an upper end sized to engage a cylindrical upper riser section of the nuclear reactor. The riser cone defines a compression sealing ring that is compressed between the lower riser section and the upper riser section in the assembled nuclear reactor. In some embodiments the riser cone comprises: a lower element defining the lower end of the riser cone; an upper element defining the upper end of the riser cone; and a compliance spring compressed between the lower element and the upper element. In some embodiments the riser cone comprises a frustoconical compression sealing ring accommodating a reduced diameter of the upper riser section as compared with the diameter of the lower riser section.
	abstract	A multilayer mirror for reflecting extreme ultraviolet (EUV) radiation, the mirror has a substrate and a stack of layers formed on the substrate. The stack of layers comprises layers including a low index material and a high index material, the low index material having a lower real part of the refractive index than the high index material at a given operating wavelength λ. The mirror provides a first peak of reflectivity of 20% or more at a first wavelength λ1 in a first wavelength band extending from 6 nm to 7 nm and a second peak of reflectivity of 20% or more at a second wavelength λ2 in a second wavelength band extending from 12.5 nm to 15 nm.
056429550	description	DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS During the installation procedure, the tie rod/lower spring assembly (items 54 and 56 in FIG. 2) is lowered into the downcomer annulus 16. This is accomplished using a crane (not shown) on the refueling floor of the reactor. First, the tie rod/lower spring assembly must be raised from horizontal position on the refueling floor to a vertical position suspended from the end of the crane cable. This is accomplished by means of a tie rod adaptor which couples the upper end of the tie rod to the end of the cable. When the cable is wound, the upper end of the tie rod is lifted off the refueling floor into an upright position with all of the weight of the tie rod being supported by the cable. The tie rod/lower spring assembly can then be lowered into the annulus by unwinding the cable. Referring to FIGS. 3A and 3B, when vertical access to the downcomer annulus 16 is limited by internal reactor structures such as the feedwater sparger 14 and core spray header 15, the tie rod adaptor 100 is coupled to the end of the cable 84 via a rigid frame or strongback 90 specially designed, in accordance with the present invention, to bypass the obstruction. Maneuvering of the tie rod/lower spring assembly must be done with extreme care to avoid damaging reactor hardware such as the jet pump sensing lines. Referring to FIGS. 5A and 5B, the tie rod adaptor 100 comprises a frame 102 having a hole 104 for receiving a conventional coupling mechanism, such as a clevis pin, which must be strong enough to bear the entire weight of the tie rod/lower spring assembly. A circular cylindrical shield 106 for protecting the threads of the tie rod is connected to the frame 102 by means of a mounting plate 108. The frame 102 has an axial recess 114 shaped for receiving the upper end of the tie rod, and a pair of circular cylindrical holes 116a and 116b which communicate with axial recess 114. Each hole 116a and 116b has a respective bushing 118a and 118b in which a respective locking pin 120a and 120b is slidably mounted. Each locking pin is slidable from a first position whereat the locking pin does not interfere with axial recess 114 to a second position whereat the locking pin interferes with axial recess 114, as seen in FIG. 5B. Each locking pin 120a, 120b slides from the interfering position to the non-interfering position in response to actuation of a respective pneumatic cylinder 122a, 122b. The piston of pneumatic cylinder 122a is connected to a reduced-diameter end of locking pin 120a; the piston of pneumatic cylinder 122b is connected to a reduced-diameter end of locking pin 120b. As best seen in FIG. 5B, each cylinder is protected against damage by a respective U-shaped cylinder shield 126a, 126b attached to frame 102 via screws. Each locking pin 120a and 120b is disposed radially relative to the axis of the tie rod and is configured to fit with little play inside a respective one of circular cylindrical radial holes 58a and 58b formed in the topmost portion of the tie rod upper end, as shown in FIG. 4, and inside a respective one of the bushings 118a and 118b. The front end of each locking pin is chamfered to facilitate entry of the locking pin into the radial holes 58a and 58b. In the preferred embodiment, the holes 58a and 58b are mutually perpendicular, as are the locking pins 120a and 120b. Each locking pin is capable of supporting the entire weight of the tie rod, which is in excess of 1,000 pounds. Each pneumatic cylinder is connected to a separate source of pressurized fluid via a respective pneumatic line (not shown). Each piston is retracted when pressurized fluid, e.g., air, is supplied to the cylinder and extended when the supply of pressurized fluid is cut off. When the pistons are extended, they interlock the adaptor to the tie rod via locking pins 120a and 120b which extend into tie rod holes 58a and 58b (see FIG. 4) respectively. Each cylinder has a spring return which urges the locking pins to engage tie rod holes 58a and 58b when pneumatic pressure is discontinued. As a safeguard to prevent dropping the tie rod into the annulus, each locking pin is latched in the locking position by a respective latch 128. The exposed end of each latch shaft is integrally joined with a respective eyebolt 124a and 124b. The tie rod cannot be disengaged from the lifting apparatus until each latch 128 has been manually unlatched by an operator using a handling pole to lift the eyebolts. Then pressurized fluid can be supplied to disengage the locking pins 120a and 120b from the holes in the tie rod. When both locking pins are retracted, the tie rod lifting apparatus can be disengaged from the tie rod and removed from the annulus. The hole 104 of tie rod adaptor 100 is coupled by a first clevis pin (not shown) to an apertured clevis 90a (see FIGS. 6A and 6B) which forms the lower end of the strongback 90. The upper end of strongback 90, in turn, has an apertured clevis 90h which is coupled by a second clevis pin (also not shown) to a cable 84 by a cable adaptor 86 (see FIGS. 3A and 3B). The strongback must have a height sufficient to span the distance between a point above the feedwater sparget 14 to a point below the core spray elbow 19, thereby allowing a shorter cable to be used. Because the cable ends at a point above and the strongback circumvents the piping obstructions, the tie rod/lower spring assembly 54/56 can be freely suspended without the supporting hardware or cable bearing against the piping. Thus, the cable stays plumb and the position of the tie rod/lower spring assembly relative to the gusset plate 58 can be freely adjusted by displacing the cable adaptor, e.g., by displacing the crane or by exerting a lateral force on the cable. To circumvent the piping obstructions, the strongback 90 is designed to have a first rigid linear member 90c which is parallel to and offset from the reference axis A (see FIG. 6A). Strongback 90 further comprises a second rigid linear member 90e which is also parallel to and offset from the reference axis A. The rigid linear members 90c and 90e are mutually parallel and define a midsection plane. The bottom end of rigid linear member 90e is connected by a welded joint to the top end of an oblique rigid linear member 90d; the top end of rigid linear member 90c is connected by a welded joint to the bottom end of oblique rigid linear member 90d. Similarly, the bottom end of rigid linear member 90c is connected by a welded joint to the top end of an oblique rigid linear member 90b. The bottom end of rigid linear member 90b is joined to or integrally formed with the lower clevis 90a; the top end of rigid linear member 90e is connected by a welded joint to the bottom end of an oblique rigid linear member 90f. The top end of oblique rigid linear member 90f is in turn connected by a welded joint to the bottom end of a rigid linear member 90g which is coaxial with reference axis A. The top end of rigid linear member 90g is joined to or integrally formed with the upper clevis 90h. Preferably, each rigid linear member is a tube having a square cross section. Each of the welded joints connecting an oblique rigid linear member to a vertical rigid linear member is reinforced by a respective channel welded to both rigid linear members and spanning the welded joint. These reinforcing ribs bear the designations 90i-90m in FIGS. 6A and 6B. Finally, a coupling 90n is attached to oblique tube 90f such that the axis of a hexagonal socket in the head of the coupling is generally vertical and accessible from above by a tool which can be manipulated remotely to cause the strongback 90 to rotate about reference axis A during positioning of the tie rod/lower spring assembly relative to the gusset plate. The preferred embodiment of the strongback in accordance with the present invention has been disclosed for the purpose of illustration. Variations and modifications of the disclosed structure which fall within the concept of this invention will be readily apparent to persons skilled in the art of tooling design. For example, it will be apparent that not all tubes of the welded strongback assembly need to be straight. Nor does the tube cross section need to be square. All such variations and modifications are intended to be encompassed by the claims set forth hereinafter.
	description	This application claims the benefit of Provisional Application Ser. No. 60/412,836, filed Sep. 23, 2002. The present invention relates to a storage phosphor plate having a particular design, suitable for use in a flat scanner apparatus. A well-known use of phosphors is in the production of X-ray images. In a conventional radiographic system an X-ray radiograph is obtained by X-rays transmitted image-wise through an object and converted into light of corresponding intensity in a so-called intensifying screen (X-ray conversion screen) wherein phosphor particles absorb the transmitted X-rays and convert them into visible light and/or ultraviolet radiation to which a photographic film is more sensitive than to the direct impact of X-rays. In said conventional radiography (“X-ray photography”), a film plate is made by forming one or more silver halide emulsion layers on a flexible film base which is supported within a light-tight cassette. The interior of the cassette is coated with one or more X-ray sensitive luminescent layers. The cassette containing an unexposed X-ray film plate is loaded into an X-ray machine, and after exposure the cassette and exposed X-ray film plate are removed for development and fixing of the latent image produced. This is usually done automatically by feeding the cassette into a light-tight apparatus in which the cassette is opened, and the exposed film plate is extracted and passed through a series of troughs containing the various chemical processing solutions as required. The processed plate may also be dried in the apparatus. Meanwhile, a new, unexposed film plate has been loaded into the cassette which is then re-closed, and the reloaded cassette and developed film plate are delivered to respective exit slots of the processing apparatus. According to another method of recording and reproducing an X-ray pattern disclosed e.g., in U.S. Pat. No. 3,859,527, a special type of phosphor is used, known as a photostimulable phosphor, which being incorporated in a panel or screen, is exposed to incident pattern-wise modulated X-ray beam and, as a result thereof, temporarily stores energy contained in the X-ray radiation pattern. At some interval after the exposure, a beam of visible or infra-red light scans the panel or screen in order to stimulate the release of stored energy as light that is detected and converted to sequential electrical signals which can be processed to produce a visible image. For this purpose, the phosphor should store as much as possible of the incident X-ray energy and emit as little as possible of the stored energy until stimulated by the scanning beam. This is called “photostimulated light—PSL—radiography”, “digital radiography” or “Computed Radiography” (CR). Current practice in “photostimulated ligth radiography” has been to pass the exposed PSL plate in its cassette to an automatic processing machine in which the PSL plate is removed from the cassette, scanned, exposed overall to light in order to return the PSL material to its ground state and then reloaded into the same cassette for reuse. For scanning, the exposed PSL plate is transported past a laser, which scans line-wise across the plate in front of a light-guide comprising a bundle of optical fibres whose input ends are arranged in a line across the path of the plate close to the laser scanning line for the reception of light emitted, typically at wavelengths close to 400 nm, when the PSL material is stimulated by the laser. The light-guide is arranged to pass the emitted light to a photo-multiplier tube or other receptor. The result is a storable electronic raster image. The electronic image may be subjected to any desired computer image-enhancement techniques and it may be displayed on a video display unit, fed to a laser printer for the production of a plain paper copy, or used to control a laser arranged to expose correspondingly a photographic film plate to produce an X-ray plate of conventional appearance. In U.S. Pat. No. 5,340,995 there has been provided a scanning apparatus for scanning a cassette of the type used in photo-stimulable luminescence (“PSL”) radiography, which cassette comprises a flat substantially rigid base plate which is releasably securable to the base plate so as light-tightly to cover a layer of PSL material applied to a face of the base plate, characterized in that such apparatus comprises a receiving station for the receipt of a cassette into the apparatus, transport means for conveying the cassette to a separating station which includes means for separating the base plate and its cap from each other, means for transporting the base plate along a path leading through a scanning station where the plate may be scanned and, via an erasing station, to an assembly station where the plate and its cap are re-assembled, the apparatus being arranged in such a way that the cap and the base plate remain in substantially parallel relationship during their separation. The arrangement thus avoids flexure of the layer of PSL material on the plate and offers a compact construction. In U.S. Pat. No. 6,373,074 an advanced device has been described for the line by line read out of information stored in a phosphor carrier with a radiation source that can generate several individual beams, in order to emit a primary radiation providing ability to stimulate the phosphor carrier such that it emits a secondary radiation that contains at least a partial reproduction of the stored information. A receiving device for point by point reception of the secondary radiation emitted by the phosphor carrier includes a multitude of point elements, wherein the secondary radiation that is emitted by the phosphor carrier can be received at the same time by a plurality of these point elements, wherein the radiation source includes an optical device for expanding the several individual beams in the direction of a line on the phosphor carrier. Furtheron the device comprises reproduction means, located between the phosphor carrier and the receiving device, for imaging the secondary radiation emitted by the individual points of the phosphor carrier in a ratio of 1:1 on the individual point elements. An X-ray cassette has moreover been claimed in the same U.S. Pat. No. 6,373,074 for writing to a phosphor carrier contained in the cassette, the improvement wherein the cassette includes a radiation source for emitting a primary radiation that can be used to stimulate the phosphor carrier such that it emits a secondary radiation for line-by-line read out of information stored in the phosphor carrier, wherein said secondary radiation contains at least a partial image of the stored information, and wherein the cassette includes a receiving device for point-by-point reception of the secondary radiation emitted by the phosphor carrier, wherein the receiving device contains a multitude of point elements and where the secondary radiation emitted by the phosphor carrier can be received by several of these point elements at the same time. In EP-A 1 130 417 and US-Application 2001/0017356 a system for reading a radiation image has been described, said system comprising an array of imaging elements arranged to detect said radiation image and to convert it into a charge representation of said image, as well as charge integrating means coupled to said array of imaging elements for integrating an amount of charge detected by an element of said array characterized by means for determining or setting a charge amount which is expected to be detected, means for adjusting the charge storage capacity of said charge integrating means in accordance with the expected charge amount. It is clear that the image quality produced by any radiographic system using a phosphor screen, thus also by a computer radiography (CR) system, depends largely on the construction of the phosphor screen. Generally, the thinner a phosphor screen at a given amount of absorption of X-rays, the better the image quality will be. This means that the lower the ratio of binder to phosphor of a phosphor screen, the better the image quality, attainable with that screen, will be. Optimum sharpness can thus be obtained when screens without any binder are used. Such screens can be produced, e.g., by physical vapor deposition, which may be thermal vapor deposition, sputtering, electron beam deposition or other of phosphor material on a substrate. Good image quality also implies that the sensitivity and the sharpness of the system is constant over the image area. I.e. when a CR screen is scanned in a CR scanner after a flat-field exposure, the signal should be as homogeneous as possible. In order to achieve this goal a screen with a homogeneous sensitivity should be used. It is necessary as well, however, to have a scanning system that is as constant in quality as possible. An important parameter that influences the quality consistency of the system is the distance between the CR screen phosphor layer and the light detector in the CR scanner. The light collection efficiency of the light detector critically depends on the distance between the phosphor layer and the light detector. This is the case when the light detector in the scanner consists of a photomultiplier tube (PMT) and a light guide to guide the emission light to the PMT as is the case in a flying-spot scanner. This is even more so when the light detector in the scanner consists of a CCD array and a lens system (SELFOC or microlens) in order to project the emission light of the phosphor screen onto the CCD elements as in a scanner scanning line-wise or two-dimensional-area wise. In general, the larger the distance between the phosphor layer and the light detector, the lower the sensitivity of the CR system. Since the optical system in the scanner in general has a limited sharpness depth also sharpness will be affected by the distance between the CR screen and the light detector in the CR scanner. Having a variable distance between screen and light detector causes the sharpness of the image to vary over the image area, which is evidently not allowed. The only practical way of making the distance between the phosphor layer and the light detector as constant as possible is by having a light detector that is as flat as possible and a screen that is as flat as possible and by moving the flat surface of the detector over the flat surface of the screen at a constant distance. A good way of having a flat phosphor surface for scanning is by having a plate that is constant in thickness and by pushing or pulling the plate onto a very flat surface. An excellent way to achieve this is by pulling the plate onto a flat-bed in the scanner by vacuum suction. If the edges or corners of the screen are upstanding when the screen is placed onto the vacuum table, air leaks always exist at the upstanding side and the space between the screen back and the vacuum table cannot be evacuated, leading to no vacuum. Likewise, if the curvature of the screen is too large, a spacing will exist between the screen back and the vacuum table leading to air leaking and loss of vacuum. It is clear from the background as set forth above that reading out a stimulable phosphor panel having needle-shaped phosphors requires stringent demands from the point of view of flatness of the flat panel as otherwise light escapes, resulting in loss of speed (sensitivity) and image definition (sharpness). The technology as set forth even tolerates a curvature of not more than 100 μm. A “flat” storage phosphor panel as such does not provide such a reduced curvature, so that a solution therefor is highly requested. It is an object of the present invention to offer a CR system leading to an excellent image quality that is constant over the whole image area. That object has been realized by offering a CR system, making use of a screen having a binderless phosphor layer that provides ability to be flattened in the CR digitizer, wherein said binderless phosphor layer is present on a flexible carrier, the curvature of which is changed by pressure as set out in claim 1. Specific features for preferred embodiments of the invention are set out in the dependent claims. Further advantages and embodiments of the present invention will become apparent from the following description and drawing. It is clear that the disadvantages, when applying a suction table in order to provide a flat storage phosphor sheet or panel in the scanning unit, have inventively been overcome by the device in form of a hollow box carrying the storage phosphor layer on its curved top plane. Features required from the part of the physical characteristics of the storage phosphor panel when a vacuum suction table is applied, may fail, but are redundant in the context of the present invention. According to the present invention as an essential feature an X-ray cassette for computed radiography is provided, wherein said cassette has a form of a hollow box comprising top and bottom, front and rear and lateral sides, said top and bottom sides having width dimensions, between said lateral sides, and depth dimensions, between said front and rear sides, which are substantially greater than the dimensions of said front, rear and lateral sides, between said top and bottom sides, wherein said bottom side and said front, rear and lateral sides have a higher material stiffness than the top side and wherein said top side is a deformable carrier or support material, characterized in that said support material is covered with a storage or stimulable phosphor sheet layer. An X-ray cassette according to the present invention is further provided with an opening in one of the front, rear or lateral sides. Said hollow box is filled, in the inner hollow space surrounded by the front, rear and lateral sides as well as by the top and bottom sides by air, an inert gas (or a mixture of gases) or a liquid. Most preferred—and most simple—is use of air as such, as in that case no special measures have to be taken in order to close the opening (in case of use of inert gas(es) or a liquid, preferably situated in the front, rear or a lateral side when no contact is made with a pump in order to change pressure in the interior hollow space of the hollow box. Moreover use of a liquid as e.g. water, an aqueous solution or oil, although not excluded, may be of less practical use as contact of liquids with stimulable phosphors should be avoided as otherwise corrosion of phosphors by liquids may occur, reason why measures have indeed been taken in order to make the flat panels moisture-repellent or moisture-resistant as has e.g. been s described in EP-A's 1 286 363, 1 286 364, and 1 316 970. Contact with oil may make sensitivity decrease, reason why e.g. packages as described in EP-Application No. 02102069, filed Jul. 30, 2002, are recommended. As a consequence it is recommended to make use of air or another gas or mixture of gases, wherein as an alternative for air inert gases are particularly suitable for use, as e.g. nitrogen, helium or argon. In a preferred embodiment of the present invention said hollow box is thus filled with air, wherein said box is further provided with an opening in one of the front, rear or lateral sides, in order to have the same (atmospheric) pressure in the inner hollow part of the box and on the outer part thereof as long as no further connection is externally made with a source of air pressure (like a pump) in order to cause an underpressure or overpressure in the hollow inner part of the “hollow box” cassette. In a preferred embodiment according to the present invention, in view of image definition, the X-ray cassette is provided with a phosphor layer sheet covering the deformable top side as set forth, wherein said phosphor sheet layer is a binderless storage phosphor layer. The storage phosphor used in the said phosphor sheet layer of the X-ray cassette of the present invention preferably is an alkali metal storage phosphor. Such a phosphor has been disclosed in U.S. Pat. No. 5,736,069 and corresponds to the formula:M1+X.aM2+X′2bM3+X″3:cZ wherein: M1+ is at least one member selected from the group consisting of Li, Na, K, Cs and Rb, M2+ is at least one member selected from the group consisting of Be, Mg, Ca, Sr, Ba, Zn, Cd, Cu, Pb and Ni, M3+ is at least one member selected from the group consisting of Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Al, Bi, In and Ga, Z is at least one member selected from the group Ga1+, Ge2+, Sn2+, Sb3+ and As3+, X, X′ and X″ can be the same or different and each represents a halogen atom selected from the group consisting of F, Br, Cl, I and 0≦a≦1, 0≦b≦1 and 0<c≦0.2. An especially preferred phosphor for use in a panel or screen of the present invention is a CsX:Eu stimulable phosphor, wherein X represents a halide selected from the group consisting of Br and Cl, produced by a method comprising the steps of: mixing said CsX with between 10−3 and 5 mol % of a Europium compound selected from the group consisting of EuOX′, EuX′2 and EuX′3, X′ being a member selected from the group consisting of F, Cl, Br and I; firing said mixture at a temperature above 450° C.; cooling said mixture and recovering the CsX:Eu phosphor. Such a phosphor has been disclosed in EP-A-1 203 394. The phosphor is preferably vacuum deposited on the support under conditions disclosed in EP-A-1 113 458 and EP-A-1 118 540. In the most preferred embodiment the X-ray cassette according to the present invention is provided with a phosphor sheet layer comprising a binderless needle shaped CsX:Eu phosphor, wherein X represents a halide selected from the group consisting of Br and Cl. According to the present invention the X-ray cassette further has a protective layer which is provided at least as as an outermost layer covering said storage phosphor layer and, optionally, as an auxiliary layer between said storage phosphor layer and said support. A protective layer or barrier layer can, in principle, be any moisture barrier layer known in the art, but is preferably a layer of parylene. Most preferred polymers for use in the barrier layer of the present invention are vacuum deposited, preferably chemical vacuum deposited poly-p-xylylene film. A poly-p-xylylene has repeating units in the range from 10 to 10000, wherein each repeating unit has an aromatic nuclear group, whether or not substituted. As a basic agent the commercially available di-p-xylylene composition sold by the Union Carbide Co. under the trademark “PARYLENE” is thus preferred. The preferred compositions for the barrier layer are the unsubstituted “PARYLENE N”, the monochlorine substituted “PARYLENE C”, the dichlorine substituted “PARYLENE D” and the “PARYLENE HT” (a completely fluorine substituted version of PARYLENE N, opposite to the other “parylenes” resistant to heat up to a temperature of 400° C. and also resistant to ultra-violet radiation, moisture resistance being about the same as the moisture resistance of “PARYLENE C”). Most preferred polymers for use in the preparation of the barrier layer in a panel of this invention are poly(p-2-chloroxylylene), i.e. PARYLENE C film, poly(p-2,6-dichloroxylylene), i.e. PARYLENE D film and “PARYLENE HT” (a completely fluorine substituted version of PARYLENE N. According to the present invention said X-ray cassette said protective layer and said optionally present auxiliary layer, are both layers of parylene wherein said parylene is selected from the group consisting of parylene C, parylene D and parylene HT. The advantage of parylene layers as moisture barrier layers in a panel or screen of the present invention layer is the temperature resistance of the layers, the temperature resistance of the parylene layers is such that they can withstand the temperature need for vacuum depositing the storage phosphor. The use of parylene layers in storage phosphor screens has been disclosed in, e.g., EP-A's 1 286 363, 1 286 364, 1 286 362 and 1 286 365. The X-ray cassette according to the present invention further has a deformable carrier or support, wherein said deformable carrier or support material is convex, concave or plan parallel with respect to the bottom side of said cassette. Preferably said X-ray cassette has plan parallel top and bottom sides just before scanning in a scanning apparatus. Therefore as soon as the exposed X-ray cassette according to the present invention has been mounted in the scanner, the cassette is connected to an air (or inert gas) pressure device via the opening, set forth above. According to the present invention the X-ray cassette in form of a hollow box has plan parallel top and bottom sides, provided by the method of changing pressure in the hollow inner area of the cassette through an opening in at least one of the front, the rear or the lateral sides. In a preferred embodiment according to the method of the present invention deforming the carrier or support material of an X-ray cassette as disclosed hereinbefore proceeds by the steps of mounting said cassette in a scanning unit or apparatus; connecting the inlet opening of the cassette with a pump; changing pressure by sucking from or adding to the cassette air, an inert gas or a liquid. According to the method of the present invention changing pressure is applied to such an extent that the stimulable phosphor sheet layer is deformed in that its curvature is minimized, wherein said curvature is continuously measured by a device or apparatus connected with or present nearby the scanning unit or apparatus. In a further preferred embodiment according to the method of the present invention changing pressure is stopped as soon as curvature has been measured to have been minimized, followed by starting scanning of the stimulable phosphor plate, which is provided thereby as a desired plan parallel cassette in form of the hollow box described hereinbefore. According to another embodiment (and expressed in a more quantitative way) changing pressure is stopped by stopping the pump as soon as curvature has been measured to have been minimized up to a tolerance level of not more than 100 μm. It is preferred to perform this action automatically by providing a device measuring curvature of the storage phosphor layer onto the top side of the box, wherein said device is connected with the scanning apparatus as a detector. According to the method of the present invention the same detector gives a signal to the scanning apparatus in order to start the scanning procedure as soon as curvature has been measured to be minimized. Normally pressure in the inner part of the hollow box is held constant during scanning, but means for correcting may additionally be provided in order to further optimize the tolerances of curvature in order to avoid them to exceed a value of 100 μm, which is already a quite severe condition as set forth above. It is clear that according to the method of the present invention pressure changes are provided by suction of air (or an inert gas) from the inner area of the hollow box as long as the storage phosphor panel is convex with respect to the bottom side of the X-ray cassette or blowing of air (or an inert gas) into the inner area of the hollow box as long as the storage phosphor panel is concave with respect to the bottom side thereof. It is an essential feature of the hollow box, that the top plane carrying the stimulable phosphor layer, has a material stiffness that is lower than the material stiffness of the bottom plane and the side walls (called “front”, “rear” and “lateral” sides) respectively. The requisite stiffness or rigidity against bending or flexing should be present along any directions, apart for the top layer direction as the said top layer should be deformable. Differences in material stiffness, if appearing, between bottom plane and side walls should indeed be smaller than between top plane carrying the stimulable phosphor layer and the side walls in order to allow changes in pressure in the hollow space area of the hollow box, without substantially deforming the said bottom plane or side wall surfaces. Preferred materials for the side walls and the bottom side are e.g. aluminum, tungsten, stainless steel, titanium, brass. The deformable top side carrying the stimulable phosphor layer may be composed of the same material as that of the bottom side, provided that e.g. thickness of the bottom side layer is substantially higher than that of the top side layer. In the alternative other materials may be provided such as e.g. a-C (amorphous carbon), Cu, heat resitant resins such as PTFE (polytetrafluorethylene), fluorocarbon resin and acrylic resins. The said changes in pressure are, in one embodiment, provided as an underpressure, decreasing pressure in the hollow box device having a convex upper or top surface plane, wherein the tube perforating the side walls (the front, the rear or one of the lateral walls) performs a suction action upon the air present in the said hollow box device. In the alternative the said changes in pressure are, as expressed in another way, provided as an overpressure, increasing pressure in the hollow box device having a concave upper or top surface plane, wherein the tube perforating the side walls (the front, the rear or one of the lateral walls) performs a blowing action upon the air (or inert gas) present in the said hollow box device. In order to avoid twisting and warping of the side walls it is recommended to have the side walls present as a rigid frame arranged along said, front rear and lateral sides of the device in order to provide sufficient material stiffness able to withstand deformation more than the deformable top or upper surfacer plane carrying the stimulable phosphor layer. It is recommended to provide a rapidly measuring device having sufficiently short reaction time in order to determine curvature of the storage phosphor layer on top of the hollow box and in order to stop changes in pressure applied upon the air inside the hollow box s as soon as flatness of the top surface area is optimized, or, expressed otherwise, as soon as curvature is minimized. The said device measuring curvature of the phosphor layer on top of the hollow box is preferably built in in the scanning device and preferably acts as a controlling device inhibiting starting the scanning action of the storage phosphor plate as long as no minimized curvature has been reached or, in the alternative, provoking starting the said scanning action as soon as a minimized (or optimized) curvature has been measured. Before starting the scanning action the measuring system provides a signal whether pressure should be increased (in case of a negative curvature, still present if the hollow box still has a concave surface) or decreased (in case of a positive curvature, still present if the hollow box still has a convex surface). In a preferred embodiment the measuring device calculates differences (changes) in curvature as a function of changes in pressure and accurately determines when these changes are minimized. As the measuring device searches for the equilibrium point where pressure changes are minimized, pressure changes are stopped at that point and a signal is directed to the scanner in order to start up the scanning procedure. Pressure changes caused by an air pump may be performed continuously or discontinuously and may be constant as a function of time or variable. In praxis the upper or top side of the hollow box is thin (in the range from 0.2 mm up to 1 mm) and is easily deformed by an over- or underpressure. As the bottom side should be more solid (less deformable) in order to keep its shape, it is recommended to provide a thickness for the bottom side which is 2 to 5 times the thickness of the bottom side. As desired the upper surface carrying the phosphor will deform most by a changes in pressure whereas the bottom surface will retain its flat form. Distances between top and bottom layer inside the hollow box may vary in the range from 1 mm up to 10 mm. At the side of the lateral walls of the box an inlet opening is provided in order to change the pressure within the box. The said pressure within the box may be changed from 0.1 bar (underpressure) up to 2 bar (overpressure) by a pumping air or an inert gas. The material can be aluminum (available as a relatively thin, lightweight sheet material), Cu or steel. Using steel will obtain a longer lifetime, because it can be deformed many times before it cracks. Also plastics or resins can be used because these materials are showing a good flexibility. While pressure has been changed upon the upper or top layer, the said upper or top layer becomes flat. In order to detect the flatness (lack for curvature) of the top layer, the detector can be placed in the middle of the box. The said flatness can also been detected indirectly by analysing the image that is scanned. A larger signal in the middle of the image is caused by a smaller distance from the phosphor to the detector when the top surface is convex, and can be corrected by decreasing the pressure. The pressure may be varied until the signal in the middle of the image is equal to the signal at the borders when a flatfield is taken. At that moment the hollow box has plan-parellel top and bottom sides as requested for a scan providing excellent image quality. In an alternative embodiment the hollow box is conceived as a “double” hollow box, in that the box is divided into two hollow spaces, divided by a stiff support inbetween, wherein both spaces are filled with a gas (air, an inert gas, mixtures of different gases) or a liquid and wherein at both sides a flexible support is carrying a storage phosphor layer. Said storage phosphor layers, again are covered with a protective layer each, and, optionally an intermediate layer is present. A preferred composition for said protective and said optional intermediate layers again is parylene as explained hereinbefore. The two flexible sides (on the top and bottom side respectively) preferably have an equal curvature when in the internal stiff support a hole provides entrance in both hollow spaces of gas or liquid, but as such a construction is not self evident it is preferred to have the two hollow spaces completely separated one from another in order to controll curvature of both phosphor sides independently as has been described for the hollow box having only one storage layer on the top side. Two independent inlets for making connection with a pump system are required in this arrangement, and, in order to provide excellent flatness at both the top and bottom storage panel, an apparatus for measuring curvature is also more complicated as two measurements changing curvature as a consequence of changing pressure in the two hollow spaces should be performed. In such a construction of a “double hollow box”, covered at both sides with a storage phosphor sheet or layer, read-out should be performed in reflection, so that the flexible carrier supports should not necessarily be transparent anymore. It is clear that the “double hollow box”, after having been deformed in order to get two plan parallel storage phosphor panels should be as thin as possible in the whole arrangement of a flat panel as envisaged. In order to provide absorption of radiation by the supporting material of the box in an amount as low as possible, it is clear that the material should be selected as a function thereof. Preferred thereof is amorphous carbon (a-C) already mentioned before and described in e.g. in EP-Application No. 02100764, filed Jun. 28, 2002, wherein said supporting material with low absorption of penetrating radiation is known to have a high mechanical strength. In view of the object to guarantee efficient creation and detection of photostimulated light, without leading to reduced resolution, i.e., to offer a CR screen that simultaneously provides high sensitivity and good resolution, the supporting layer preferably has a reflectivity of more than 80% as described e.g. in EP-Application No. 02100763, filed Jun. 28, 2002. So an aluminum layer coated onto an amorphous carbon support forms a highly preferred support arrangement for the storage phosphor sheet or panel. Furtheron care must be taken that no impress or imprint is present on the image obtained as a consequence of pressure changes, applied to the deformable sides of the box, carrying the storage phosphor sheet or layer, as such an impress or imprint lays burden upon the diagnostic value of the image obtained. Procedures for double-side reading of storage phosphor panels as described e.g. in U.S. Pat. Nos. 5,534,710; 5,880,476 and 6,344,657 may be applied wherein a procedure of a combined reading and erasing step in parallel has been described, which is very advantageous from the viewpoint of performing a radiation image recording and reproducing method quickly and efficiently, free from reproducing noisy radiation images. Such a system is further recommended as it is advantageous because the whole apparatus can be constructed in a relatively small size. Just as in U.S. Pat. No. 5,591,982 a radiation image storage panel may be provided wherein storage phosphor layers are colored, e.g. in case of binderless storage phosphor panels as recently disclosed in EP-Application No. 02100296, filed Mar. 26, 2002. Differences in amounts of dyes for both storage panels provide an excellent sharpness and graininess for the radiation image reproduced in the double-side reading system of the present invention as is provided by a “double hollow box”. In double-side reading, by carrying out e.g. an addition process on signals obtained from both sides at pixels corresponding to each other, light collection efficiency improves and noise components are averaged, so that a signal to noise ratio of a radiation image obtained in this manner can be improved. In case of asymmetric arrangements of storage panels, i.a. when storage phosphor sheets having same phosphors but differing amounts of phosphor coated and/or differing amounts of dye present, measures should be taken in order to discriminate top and bottom side of the “double box” from each other, e.g. by providing a shape of the radiation image storage panel being asymmetric with respect to a center axis of the radiation image storage panel, which center axis may extend in an antero-posterior direction of the radiation image storage panel as has e.g. been described in US-Application No. 2001/035502. Identification means may further be present onto the hollow box, and, in order to avoid loss of information due to partial coverage of the flat panel by said identification means, the said identification may be provided onto the front, the rear and/or lateral sides of the hollow box in form of e.g. a bar code or a magnetic strip, without however being limited thereto. So first and second bar codes just as e.g. described in EP-A 1 039 338 may be effective, if applied in the present invention, in order to determine whether one or two stimulable phosphor sheet(s) is(are) housed in the cassette is either a “single-sheet” or a “double-sheet” hollow box and for the user to register ID information. Apart therefrom information dimension data of a storage phosphor contained in the cassette may be provided as has e.g. been described in EP-A 0 903 618. An identification system for matching the X-ray radiation image obtained from a patient and the identification information may further be provided, as is known e.g. from EP-A 0 603 511. Light-weight materials are recommended in order to build up the hollow box of the present invention, especially in favor of manutention. In as far as the materials for use as supporting materials have a high mechanical strength and show enough heat-resistance in order to survive chemical vapor depositions of e.g. parylene layers and binderless storage phosphor layers, such materials are suitable as e.g. amorphous carbon and heat-resistant resins such as PTFE (polytetrafluorethylene) as a preferred fluorocarbon resin. Opposite thereto acrylate resins are only suitable as stiff, non-deformable support material, as being not enough heat-resistant in the conditions as envisaged in the preparation method of the hollow box of the present invention. Another light-weight material as e.g. “hylite” (an aluminum-polypropylene-aluminum combination mentioned in EP-A's 0 905 715 and 0 919 859) may also be used. According to the present invention a method for producing an X-ray cassette in form of a hollow box as disclosed above is given, said method comprising the steps of: providing a hollow box having plan parallel bottom and top sides, vacuum depositing a storage phosphor layer on said top side, vacuum depositing a protective parylene layer onto said storage phosphor layer. Further according to the present invention, in another more complicated embodiment in favor of increased speed, a method is offered for producing an X-ray cassette in form of a hollow box as disclosed before, said method being characterized by the steps of providing (on one hand) a hollow box having plan parallel bottom and top sides, vacuum depositing a protective parylene layer onto said top side, providing (at the other hand) a storage phosphor layer having been coated or deposited onto a support from which it is releasable, laminating said storage phosphor layer onto said parylene layer, which covers the said hollow box, removing said support from which it is releasable, covering said phosphor layer with a protective layer. It is clear that in case of a “double hollow box” the same methods can be applied, provided that the “bottom side” as mentioned above is corresponding with the support separating the two inner hollow spaces and that each large outermost face functions as a top side, consisting of a deformable side, to be covered with a storage phosphor layer, which should further be protected by a protective layer (preferably being composed of parylene as set forth hereinbefore).
	summary
	description	This application relates to and claims priority from Japanese Patent Application No. 2004-208340, filed on Jul. 15, 2004, the entire disclosure of which is incorporated herein by reference. 1. Field of the Invention This invention relates to an information processing technology using a computer, and in particular to information processing in cases in which an anomaly occurs due to, for example, a specific fault. 2. Description of the Related Art Computer systems are known which have, for example, a host device (for example, a host computer), and first and second storage device systems (for example, disk array systems such as RAID (Redundant Array of Independent Disks)). Each of the first and second storage device systems comprises at least one logical volume. One logical volume is prepared for one or a plurality of physical storage devices (for example, hard disks) comprised by the storage device system. In such a computer system, for example, remote copy processing may be performed. In remote copying, the data in a logical volume of a first storage device system is copied to a logical volume in a second storage device system, without passing through a host device. The logical volume which is the copying source of the remote copying is called the copy source volume, and the logical volume which is the copying target of the remote copying is called the copy target volume. The copy source volume and copy target volume may, for example, have the same storage capacity and form a one-to-one relationship (in others, form a copy pair). The data in the copy source volume is copied to the copy target volume via a remote copy line (for example, a dedicated circuit, public circuit, or similar) connecting the first and second storage device systems. In remote copying, the copying direction is for example unidirectional, and in the even of write requests from a host device, the copy source volume can accept a request, but the copy target volume cannot accept a request. When data contained in the copy source volume is updated (for example, when a second data item is overwritten by a first data item), the update data (for example, the difference between the first and second data items) is written to the copy target volume from the copy source volume via a remote copy line, and by this means the data in the copy source volume and the data in the copy target volume are made the same. Technology related to such remote copying is disclosed in for example Japanese Patent Laid-open No. 2003-76592 and U.S. Pat. No. 5,742,792. A computer system may comprise a plurality of host devices, such as for example first and second host devices. In such a computer system, the same logical volume may be shared by the first and second host devices (below, such logical volumes are called “shared volumes”). A shared volume is exclusively controlled. Specifically, control is executed such that access requests for a shared volume are permitted only from the first host device, and access requests from the second host device in the same time period are not permitted. More specifically, in a computer system which for example adopts SCSI (Small Computer System Interface) as the interface between host devices and storage device systems, when a first host device sends to a shared volume a reserve-system command defined by the SCSI protocol, and when the shared volume is not being used by any host device, the storage device system, upon receiving the above reserve-system command from the first host device, puts the shared volume into the reserved state with respect to the first host device, and by this means can ensure that access requests from a second host device are not accepted. If, while the shared volume is in the reserved state with respect to the first host device, a request to access the shared volume is received from the second host device, the storage device system returns to the second host device status data (for example, data indicating the reservation conflict status) indicating that the shared volume has been reserved by another host device. A host device comprises, for example, application software (henceforth called an “application”) and driver software for the storage device system (henceforth called “disk control software”). An application can issue I/O requests for writing of data to a logical volume or for reading of data from a logical volume, according to user operations or other conditions. Disk control software can receive an I/O request issued by an application, convert the I/O request into a format which can be processed by the storage device system (for example, a format based on the SCSI protocol), and send the converted I/O request to the storage device system. Also, disk control software may for example receive data indicating an anomaly status (henceforth called “anomaly status data”) from the storage device system as a response to an I/O request. When anomaly status data which has been received indicates a specific anomaly status, the disk control software can execute rewrite processing, such as for example processing to again send to the storage device system a converted I/O request which has been sent in the past, as described above. However, a plurality of host devices can be connected to configure a cluster. In this case, each of the host devices (hereafter, for convenience, called “cluster servers”) comprised by the cluster is equipped with, for example, software (hereafter “cluster software”) to realize the cluster. Below, for convenience, resources managed by a cluster (for example, physical storage devices and other hardware, as well as database management system and other software) are called “cluster resources”. A computer system comprising a cluster is called a “cluster system”. By performing what is called fail-over processing, a cluster system can continue usage of cluster resources. Specifically, when for example use of a certain cluster resource by a certain cluster server cannot be continued due to the occurrence of a fault in the cluster server, the cluster software within the cluster server performs fail-over processing, that is, performs processing to switch use of the above cluster resource to another cluster server which is operating normally, so that use of the cluster resource can be continued. The plurality of cluster servers comprised by the cluster system are connected by a network using the Internet protocol (IP) or similar. The cluster software in each of the cluster servers, by communicating with other cluster servers over this network, monitors the states of the communicating cluster servers. This communication is called “cluster communication” or “heartbeat communication”. A cluster system in which a plurality of cluster servers share a single storage device system is called, for example, a shared disk model cluster system. In a shared disk model cluster system, when for example the heartbeat communication between two cluster servers is cut off, each of the two cluster servers can confirm the operating state of the other cluster server through shared exclusive control using a shared volume, and by this means it is possible to prevent a state (hereafter called a “split-brain” state) in which the two cluster servers operate separately. Below, for convenience, control performed to prevent such a split-brain state (in the above example, shared exclusive control) is called “arbitration”. Cluster software for realization of shared disk model cluster systems comprises software to, for example, perform shared exclusive control (that is, requesting that the disk control software issue reserve-system commands) for storage disks used to perform arbitration (called, for example, arbitration disks, arbitration volumes, or quorum disks) using SCSI commands, by this means avoiding a split-brain state. For example, cluster software can periodically issue I/O requests to a storage device system via disk control software, reference response results received via the disk control software from the storage device system in response, and monitor the state of the storage device system receiving the I/O requests. When a response request is an anomaly status, the cluster software judges whether a fault has occurred, and can execute the above-described fail-over processing. Cluster software has been disclosed in for example U.S. patent application Ser. No. 6,279,032 and U.S. patent application Ser. No. 6,401,120. However, when in the above-described technology of the prior art the disk control software, for example, receives anomaly status data indicating a specific anomaly status (as an example, a timeout), retry processing, such as for example. executing processing to again transmit to the storage device system an I/O request transmitted in the past, may be performed without reporting the anomaly to the higher-level application. When in response to this the specific anomaly status data is again received, the disk control software may again execute retry processing without reporting the anomaly to the higher-level application. The disk control software may repeat the above-described retry processing, without reporting the anomaly to the higher-level application, for the number of retry times set by a user in advance, or until there is recovery from the anomaly and data indicating normal status is received. When an anomaly report is received from the disk control software, cluster software, which is one application, can judge that an anomaly has occurred and initiate the above-described fail-over processing. In other words, until the cluster software receives the anomaly report from the disk control software, the same state is maintained without initiation of the fail-over processing. As a consequence, the initiation of fail-over processing is delayed. Problems of a nature similar to the above-described problem can conceivably exist in various systems other than cluster systems. For example, in a system in which an intermediate information processing portion intervenes between an information issuing portion and a resource portion, when the intermediate information processing portion issues information to the resource portion in response to information from the information issuing portion (for example, a request relating to resource use), and receives an anomaly report from the resource portion in response to this information, if the information is reissued to the resource portion at least once without informing the information issuing portion of the anomaly, and if the information issuing portion is to be notified of the anomaly when an anomaly is again received, then there exists the problem of a delay in notification of the information issuing portion of the anomaly. Hence an object of this invention is to ensure that there is no delay of initiation of processing by the information issuing portion in response to an anomaly, even when the information processing system is configured such that the intermediate information processing portion reissues information without reporting an anomaly to the information issuing portion. Specifically, one object of this invention is to ensure that there is no delay of initiation of fail-over processing by cluster software, even when disk control software is configured to reissue an I/O request upon receiving an anomaly report without reporting the anomaly to the cluster software. Still other objects of the invention will become clear from the following explanations. An information processing system (hereafter called the “first information processing system”) according to a first aspect of this invention can communicate with a storage system, and comprises a program storage area which stores a plurality of computer programs, a fault storage area which stores fault data which is data relating to specific faults, and at least one processor which reads and executes at least one computer program from the above storage area. The above plurality of computer programs comprise an information issuing program which issues information, an intermediate processing program, and an information filter program. The intermediate processing program receives and outputs information issued by the above information issuing program, and when an anomaly report is received in response to the above information output, prior to notifying the above information issuing program of the anomaly, again re-outputs the above output information at least once, and, if an anomaly report is received even after re-outputting the information one or more times, notifies the above information issuing program of the anomaly. The information filter program receives information issued by the above intermediate processing program, judges whether fault data is stored in the above fault storage area, and, if the above fault data is not stored, outputs the above received information to the above storage system, whereas if the above fault data is stored, notifies the above intermediate processing program of the anomaly in response to reception of the above information. The information processing system may comprise a storage system. The storage system may be a storage device (for example, a hard disk drive), or may be a storage device system comprising a plurality of storage devices. When the above fault data is not stored, the information filter program may notify the above intermediate processing program of the anomaly without outputting the received information to the storage system (for example, erasing the information). A “specific fault” may be, for example, a fault related to the storage system, or may be a fault related to the information processing system without being related to the storage system (for example, a fault related to the copy control of the copy control program described below). Further, the intermediate processing program may output exactly the same information received from the information issuing program, or may output information derived from the received information (for example, as the result of conversion into a format which can be interpreted by the storage system). Further, an “anomaly” exchanged within the first information processing system is, for example, data representing an anomaly. According to a first embodiment of the first information processing system, the above storage system processes information issued by the above information processing system, and when the above information is processed normally, processing result data indicating normal processing is returned to the above information processing system, whereas when the above information cannot be processed normally, processing result data indicating an anomaly is returned to the above information processing system. In this case, the above information filter program receives the processing result data returned from the above storage system, and when the above received processing result data indicates normal processing outputs a normal result to the above intermediate processing program, but when the above received processing result data indicates an anomaly, stores the above fault data in the above fault storage area, and also outputs the anomaly to the above intermediate processing program. According to a second embodiment of the first information processing system, in the above first embodiment, the above intermediate processing program issues information having an identifier. When the above received processing result data indicates an anomaly, the above information filter program registers the identifier of the information corresponding to this processing result data in the above fault storage area, and upon receiving information from the above intermediate processing program, if an identifier conforming to the identifier of the above received information is registered in the above fault storage area, notifies the above intermediate processing program of the anomaly. According to a third embodiment of the first information processing system, the above storage system comprises a first logical volume. The first logical volume can form a pair with a second logical volume. The second logical volume is comprised by either the above storage system, or by another storage system connected to the above storage system. In the latter case, the above plurality of computer programs further comprises a copy control program which executes control related to copying of data between the above first logical volume and the above second logical volume, and which, if the above control is not performed normally, outputs control result data indicating an anomaly. The above information filter program issues requests to execute control to the above copy control program, receives the above control result data from the copy control program in response to the above requests, and, if the above received control result data indicates an anomaly, stores the fault data in the above fault storage area, and outputs the anomaly to the above intermediate processing program. According to a fourth embodiment of the first information processing system, the above information processing system further comprises an information storage area to temporarily store information issued by the above intermediate processing program. Prior to storage of the above received information in the above information storage area, or after reading the above information from the above information storage area, the above information filter program judges whether fault data is stored in the above fault storage area. According to a fifth embodiment of the first information processing system, the above plurality of computer programs further comprise a fault recovery detection program which detects whether there has been recovery from the above specific fault, and when recovery has been detected, records the fault recovery in the above fault storage area. According to a sixth embodiment of the first information processing system, in the above fifth embodiment, the above fault recovery detection program, upon detecting that device information has been acquired relating to the above storage system, detects whether there has been recovery from the above specific fault. According to a seventh embodiment of the first information processing system, in the above fifth embodiment, the above fault recovery detection program, upon detecting that a resource (for example, a logical volume) of the above storage system is online, detects whether there has been recovery from the above specific fault. An information processing method according to a second aspect of the invention, in a system comprising an information issuing portion, an intermediate information processing portion, and a resource portion, has a step in which the information issuing portion issues information; a step in which the intermediate information processing portion receives and outputs the above issued information; a step in which the above output information is received, a judgment is made as to whether fault data is stored in a fault storage area, and, if the above fault data is not stored, the above output information is output to the above resource portion; a step in which the above resource portion receives the above output information, and, if the above received information cannot be processed normally, outputs processing result data indicating an anomaly; a step in which the above output processing result data is received, and if the above received processing result data indicates an anomaly, the fault data is stored in the above fault storage area and the anomaly is output to the above intermediate information processing portion; a step in which the above intermediate information processing portion, upon receiving an anomaly in response to the above information output, prior to notifying the above information issuing portion of the anomaly, again re-outputs the above output information; a step in which the above output information is received, a judgment is made as to whether fault data is stored in the above fault storage area, and, if the above fault data is stored, the above intermediate information processing portion is notified of the anomaly in response to the above information reception; a step in which the above intermediate information processing portion, upon receiving an anomaly in response to the above re-output, notifies the above information issuing portion of the anomaly; and, a step in which the above information issuing portion receives the anomaly and executes processing in response to the received anomaly. Recording media according to a third aspect of the invention is computer-readable recording media on which is recorded a computer program to cause a computer to execute a step of receiving information output by an intermediate processing program, which receives and outputs information issued by an information issuing program, which issues information; a step of judging whether fault data is stored in a storage area; a step of outputting the above received information to a destination when the result of the above judgment indicates that the above fault data is not stored; and a step of notifying the above intermediate processing program of an anomaly in response to the above received information when the result of the above judgment indicates that the above fault data is stored. An information processing system according to a fourth aspect of the invention communicates with a resource portion, and comprises a fault storage area which stores fault data, which is data relating to a specific fault; an information issuing portion, which issues information; an intermediate information processing portion; and an information filter portion. The above intermediate information processing portion receives and outputs information issued by the above information issuing portion, and when an anomaly is received in response to the above information output, prior to notifying the above information issuing portion of the anomaly, re-outputs the previously output information at least once, and when an anomaly is received even upon re-output at least once, notifies the above information issuing portion of the anomaly. The above information filter portion receives information issued by the above intermediate information processing portion, judges whether fault data is stored in the above fault storage area, and when the above fault data is not stored, outputs the above received information to the above resource portion, but when the above fault data is stored, notifies the above intermediate information processing portion of the anomaly in response to the above received information. The entirety of or a portion of the above-described portions or steps can be realized in hardware, in a computer program, or in a combination of both. A computer program can be fixed in and distributed by means of, for example, a hard disk, an optical disk, semiconductor memory, or similar. A computer program can also be distributed via the Internet or another communication network. The above-described information processing systems may be constructed within a single computer machine (for example, a personal computer, server, or storage device system), or may be constructed in a plurality of computer machines connected to a communication network. FIG. 17A through FIG. 17C show the concepts of a system of one embodiment of the invention, and an example of the processing flow in the system. A system of this embodiment comprises an information issuing portion (for example, the cluster software described below) 11, an intermediate information processing portion (for example, the disk control software described below) 12, a resource portion (for example, the storage device system described below) 13, and an information filter portion (for example, the arbitration emulation software described below) 14. Exchanges between the information issuing portion 11 and intermediate information processing portion 12, exchanges between the intermediate information processing portion 12 and the information filter portion 14, and exchanges between the information filter portion 14 and the resource portion 13 are performed via prescribed media. Here, various entities, such as for example communication networks, communication interfaces, recording media and similar, can be adopted as “media”. The information issuing portion 11, intermediate information processing portion 12, and information filter portion 14 can be realized as computer programs read by a CPU or other processor and executed by the processor, but are not limited to computer programs, and may also be hardware, or a combination of hardware and computer programs. The resource portion 13 may be the resources (for example, resources relating to computers) themselves, or may be a device comprising resources. Specifically, the resource portion 13 may for example be a physical storage device (for example, a hard disk or a drive comprising same), or may be a system comprising physical storage devices (for example a RAID system or other disk array system). The intermediate information processing portion 12 may be a driver (also called a “device driver”) for the resource portion 13. Below, an example of the flow of processing in this information processing system is explained, divided into a case in which no faults occur in the resource portion 13 (hereafter called the “normal case”), and a case in which a fault occurs in the resource portion 13 (hereafter called the “anomaly case”). (1) Normal Case As shown in FIG. 17A, the information issuing portion 11 issues information (for example, data or commands). The intermediate information processing portion 12 receives information issued by the information issuing portion 11, converts this information into a format which can be interpreted by the resource portion 13 (hereafter called “resource information”), and issues this resource information. The information filter portion 14 receives resource information issued by the intermediate information processing portion 12, and issues this resource information to the resource portion 13. The resource portion 13 processes the received resource information, generates information indicating the result of processing (hereafter “processing result information”), and issues the generated processing result information. Processing result information may be, for example, normal information indicating that processing has ended normally, or anomaly information indicating that an anomaly has occurred. The information filter portion 14 receives the issued processing result information, and upon detecting that the processing result information is normal information, issues the received processing result information to the intermediate information processing portion 12. The intermediate information processing portion 12 receives the processing result information issued by the information filter portion 14, and upon detecting that the processing result information is normal information, issues the processing result information to the information issuing portion 11. By this means, the information issuing portion 11 receives processing result information as the processing result of information issued by itself, and from this processing result information can ascertain that processing has been performed normally. It is assumed that in a normal case, the time required from the time the information issuing portion 11 issues information until the time the processing result is received is T (where, for example, T is a number other than 0) (in the anomaly case described below also, it is assumed that at least time T is required from the time information is issued until reception of the processing result). (2) Anomaly Case Operation from the issuing of information by the information issuing portion 11 until processing by the resource portion 13 is similar to that in the normal case. However, a fault occurs in the resource portion 13, so that the resource portion 13 issues anomaly information as the processing result information. When the information filter portion 14 detects that the received processing result information is anomaly information, error data indicating an error is set in a prescribed storage area 16. The information filter portion 14 then issues anomaly information to the intermediate information processing portion 12. The intermediate information processing portion 12, upon receiving anomaly information, performs retry processing, by for example re-issuing the resource information issued in the past (specifically, the resource information corresponding to the anomaly information) without transmitting the received anomaly information to the information issuing portion 11. The information filter portion 14, upon receiving re-issued resource information, and if error data i sset, transmits the anomaly information to the intermediate information processing portion 12 in response to the resource information, without sending the received resource information to the resource portion 13. This processing is performed each time the intermediate information processing portion 12 performs retry processing. If the intermediate information processing portion 12 executes retry processing a maximum number of times (for example, four times) set in advance, yet still receives anomaly information from the information filter portion 14, then the anomaly information is sent to the information issuing portion 11, without performing retry processing. By this means, the information issuing portion 11 receives processing result information as the processing result of information issued by itself, and from this processing result information can ascertain that an anomaly has occurred; in this case, second processing (for example, if the system is a cluster system, fail-over processing) can be initiated in response. In the anomaly case, the length of time from the time the information issuing portion 11 issues information until the processing result is received appears from FIG. 17B to be longer than T (where for example T is a number other than 0), but in actuality can be set equal to T. At the least, in a system comprising an information filter portion 14 as in this embodiment, the time is shorter than the length of time (for example, five times T) during which retry processing is being performed the same number of times by the intermediate information processing portion 12, as shown in FIG. 17C. According to this embodiment, even if the intermediate information processing portion 12 is configured such that when anomaly information is received retry processing is executed without notifying the information issuing portion 11, the retry processing can be ended quickly, so that the information issuing portion 11 can be made to detect the anomaly quickly, and second processing can be initiated more quickly. The various constituent components of the above system can for example be arranged in a communication network. For example, the information issuing portion 11, intermediate information processing portion 12 and information filter portion 14 can be comprised by a single host device, or can be distributed among a plurality of host devices. Also, the resource portion 13 may be comprised by the same host device, or by a different device, such as for example a storage device system (such as a RAID system). Below, examples of application to a cluster system of a system of an embodiment of this invention are considered, and a number of examples are explained. FIG. 1 is a block diagram which shows in summary the entirety of a cluster system of a first example of an embodiment of this invention. A cluster system comprises, for example, a first site 10A and second site 10B; the sites 10A and 10B are connected by communication networks CN12 and CN13. A cluster system can also comprise three or more sites. The first site 10A and second site 10B can be positioned, for example, in separate cities. Also, the first site 10A and second site 10B can for example be positioned at different locations in the same administrative district. Or, the first site 10A and second site 10B can for example be provided within different buildings within the same location. The first site 10A and second site 10B comprise essentially the same configuration. As one example, the first site 10A is a current site (operating site) which provides information processing services to a client machine, not shown. The second site 10B is a backup site (standby site) which backs up data, in anticipation of the occurrence of a fault in the first site 10A. It is not in fact necessary to use an entire site as an operating site or as a standby site; each application program providing information processing service can be set as either an operating site program or as a standby site program. For example, the operating site of a first application program can be a first site 10A, and the operating site of a second application program can be set as a second site 10B. The first site 10A comprises a or more host devices HA1 through HAn (HAn is not shown), and a storage device system 10A. Each host device HA1 through HAn is configured as, for example, a server machine using a microcomputer. The storage device system 20A can be configured for example as a disk array subsystem. As described below, the storage device system 20A comprises a plurality of logical volumes 212, and these logical volumes 212 are used by the host devices HA1 through HAn. Each of the host devices HA1 through HAn is connected to a storage device system 20A via a communication network CN11 within the site. This communication network CN11 is configured for example as a SAN (Storage Area Network), and performs data communication according to a fiber channel protocol. Each of the above host devices HA1 through HAn is connected to other host devices via a communication network CN12. Each of the host devices HA1 through HAn of the first site 10A is also connected to a or more host devices HB1 through HBn (HBn is not shown) of the second site 10B via the communication network CN12. This communication network CN12 between host devices comprises, for example, the Internet, a LAN (Local Area Network), a WAN (Wide Area Network), a MAN (Metropolitan Area Network), or a similar network, and performs data communication based on TCP/IP (Transmission Control Protocol/Internet Protocol) or another protocol. The second site 10B, like the above-described first site 10A, comprises a plurality of host devices HB1 through HBn and a storage device system 20B. These are configured similarly to that described for the first site 10A, and so an explanation is omitted. Here, the storage device system 20A and storage device system 20B are directly connected by a remote copy line CN13 as a storage device network. The remote copy line CN13 is for example configured from a dedicated line or public line. A network within a site CN11 is not limited to use of a fiber channel protocol, but may for example encapsulate SCSI commands in IP packets, as in iSCSI, to execute block-level data transfers over an IP network. Below, representative examples of a host device HA1 and storage device system 20A are explained. The following explanation of a host device HA1 and storage device system 20A can also be applied to other host devices and other storage device systems. A host device HA1 comprises, for example, a CPU 310, memory 320, disk 330, disk interface (hereafter “I/F”) 340, host network I/F 350, keyboard switch 360, and display 370; these portions are interconnected by a bus 380. The CPU (Central Processing Unit) 310 reads and executes program code stored in memory 320. By executing prescribed program code, the CPU 310 realizes cluster control, remote copying control, and various other processing or functions on the host device HA1. The memory 320 comprises, for example, ROM (Read-Only Memory) and RAM (Random Access Memory) or similar. In the drawing, ROM and RAM are not differentiated, but in actuality, ROM which stores program code and similar, and RAM which is used as a temporary stage area, work area or similar, may be provided. The disk 330 is for example configured as a hard disk drive. The disk 330 stores, for example, programs and data. A portion of the storage area of the disk 330 may be used as a temporary area for storage of temporary files. The disk I/F 340 is an interface circuit which controls data exchanges with the storage device system 20A via the site network CN11. The disk I/F 340 is for example based on SCSI, iSCSI or similar, and controls block-level data transfer. The host network I/F 350 is a circuit which controls data exchange with other host devices (HAn, HB1 through HBn) via the host device network CN12. The host network I/F 350 controls data transfer based for example on the IP (Internet Protocol). The keyboard switch 360 is one example of information input means; a system manager can input necessary instructions and similar via the keyboard switch 360. The display 370 is an example of information output means, and can for example comprise a CRT (Cathode Ray Tube) display, liquid crystal display, plasma display, EL (Electroluminescent) display, or similar. The display 370 can display various information, either in response to an explicit request from a system manager, or spontaneously. The input and output means are not thereto limited, and for example a voice input device, voice output device, pointing device, printer, and similar may be used. The hardware configuration of the storage device system 20A is explained. The storage device system 20A comprises, for example, a RAID group 210, disk control portion 220, host device I/F 230, device I/F 240, cache memory 250, shared memory 260, switching control portion 270, and service processor (SVP) 280. The RAID (Redundant Array of Independent Disks) group 210 comprises a plurality of physical storage devices (hereafter “physical storage devices”) 211, and provides redundant storage based for example on RAID 1, RAID 5, or similar. Each physical storage device 211 can comprise, for example, a hard disk drive, semiconductor memory device, optical disk drive, magneto-optical disk drive, or other storage device. At least one logical volume 212, which is a logical storage area, can be configured on the physical storage areas provided by each physical storage device 211. A logical volume 212 stores a large amount of data used by host devices H. Further, another logical volume 212 can also store control information and similar, and can be used as a system area. A physical storage device 211 need not be positioned entirely within the housing of the storage device system 20A. For example, a logical volume on another storage device system (not shown) positioned within the same site can also be used as a logical volume of the storage device system 20A. In the following explanation, a logical volume may be abbreviated simply to “volume”. The disk control portion 220 controls data exchange with each of the physical storage devices 211. The disk control portion 220 is configured, for example, as a microcomputer system comprising a CPU, ROM, RAM, and similar. A plurality of disk control portions 220 are provided within the storage device system 20A. The disk control portion 220 performs block-level data transfer with physical storage devices, based for example on SCSI, iSCSI, or similar. The host device I/F 230 controls data transfers with host devices H via the site network CN11. The host device I/F 230, similarly to the disk control portion 220, can be configured as a microcomputer system. Host device I/Fs 230 can be prepared according to the type of host device H (server, mainframe, or similar). In this example, an example is explained in which a host device H is configured as a server, but the device may be a mainframe. The device I/F 240 performs data communication with the storage device system 20B of the other site 10B via the remote copy line CN13. The device I/F 240 transfers update data and differential data written to the logical volume 212 to the other storage device system 20B, without passing through the host device H. The cache memory 250 can for example be configured from volatile or nonvolatile semiconductor memory. The cache memory 250 stores write data (data written to a logical volume) from the host device H. The cache memory 250 also stores data read from a logical volume 212 (below called “read data”). Shared memory 260 can for example be configured from nonvolatile or volatile semiconductor memory. Shared memory stores, for example, various commands received from the host device H, control information used in control of the storage device system 20A, and similar. These commands, control information and similar are stored redundantly in a plurality of shared memory units 260. The cache memory 250 and shared memory 260 can be configured as separate memory devices; or, a portion of a memory device can be used as a cache memory area, and the remainder can be used as a shared memory area. The switching control portion 270 connects the disk control portions 220, the host device I/Fs 230, the device I/F 240, cache memory 250, and shared memory 260. The switching control portion 270 can for example be configured from an ultra-high-speed crossbar switch or similar. The SVP 280 collects and monitors the states of various portions within the storage device system 20A, via the host device I/F 230. The SVP 280 outputs information collected on internal states to an external management terminal (not shown), either as unmodified raw data, or as statistically processed data. Information which can be collected by the SVP 280 includes, for example, device configurations, power supply alarms, temperature alarms, input/output speeds (IOPS), and similar. A system manager can set and modify the RAID configuration and perform processing to block various packages (host device I/F, disk control portion, and similar) from a management terminal via the SVP 280. Next, an example of processing performed by the storage device system 20A is explained. The host device I/F 230 receives write commands and write data from a host device H via the site network CN11. A received write command is stored in shared memory 260, and received write data is stored in cache memory 250. The disk control portion 220 references the shared memory 260 as necessary. The disk control portion 220, upon discovering an unprocessed write command stored in the shared memory 260, reads the write data from cache memory 250 according to the write command, and performs address conversion and similar. The disk control portion 220 stores the write data in physical storage devices 211 of the logical volume 212 specified by the write command. A case of processing of a read request from a host device HA1 is explained. The host device I/F 230, upon receiving a read command from the host device HA1, stores the read command in shared memory 260. The disk control portion 220, upon discovering the unprocessed read command in the shared memory 260, reads data from the physical storage devices 211 of the logical volume 212 specified by the read command. The disk control portion 220 stores the read data in cache memory 250. Also, the disk control portion 220 notifies the host device I/F 230, via the shared memory 260, of the fact that reading of the requested data has been completed. The host device I/F 230 reads the data from the cache memory 250, and transmits the data to the host device HA1. The above is an example of the hardware configuration of the cluster system of this example. Of course the site 10A, host device HA1 and storage device system 20A are not limited to the above-described configurations. FIG. 2 shows various computer programs which operate within a host device HA1. Below, the host device HA1 within the first site 10A is explained as a representative example. In order to aid understanding of the explanation, “a” is appended to reference numbers for computer programs in the host device HA1, and “b” is appended to reference numbers for computer programs in the host device HB1 within the second site 10B. In this example, one logical volume 212a comprised by the storage device system 20A forms part of a copy pair for remote copying, and another logical volume 212b comprised by the storage device system 20B forms the other part of the copy pair. Each of the two logical volumes 212a and 212b forming the copy pair is connected to a plurality of host devices, and the copy pair for remote copying is handled as a single shared volume. In FIG. 2, one or more of the physical storage devices comprised by one of the logical volumes 212a of the copy pair is labeled “arbitration disk 211a”, and one or more of the physical storage devices comprised by the other logical volume 212b of the copy pair is labeled “arbitration disk 211b”. All the arbitration disks 211a and 211b are used in the event of “arbitration”, described in detail below. That is, in this example a first small cluster is formed by two or more host devices HA1 through HAn within the first site 10A, and a second small cluster is formed by two or more host devices HB1 through HBn within the second site 10B; a large cluster is formed by the first small cluster and the second small cluster, the logical volume 212a of the arbitration disk 211a and the logical volume 212b of the arbitration disk 211b are taken to be a single shared volume, and through this single large cluster, a single shared volume is used. The plurality of computer programs in the host device HA1 comprises, for example, an operating system (for example, Windows (a registered trademark) or Linux (a registered trademark)), not shown; cluster software 1040a; disk control software 1050a; arbitration emulation software 1060a; and remote copy control software 1070a. At least one of the software programs 1040a, 1050a, 1060a, and 1070a may be configured so as to run as an operating system, or, may be configured so as to run as one application program on the operating system. The above-described plurality of computer programs is stored, for example, on the disk 330 (see FIG. 1), are loaded from the disk 330 into memory 320, and are executed by the CPU 310. By this means, each of the plurality of computer programs executes specific processing. The cluster software 1040a is software to realize a cluster, and can, for example, detect the state of the storage device system 20A, detect the state of the host device HB1 via the host device network CN2, and execute fail-over processing. The cluster software 1040a may for example by Microsoft Cluster Server (a cluster software package provided by Microsoft Corp.). The cluster software 1040a can for example issue various requests to the disk control software 1050a. In the following explanation, a request received by the disk control software 1050a is called an “internal request”. An internal request may for example be a lock type request, or a read/write type request. A lock type request is a request related to exclusive control of use of a logical volume, and more specifically, “reserves” a logical volume used by the cluster software 1040a so as to prevent use by other host devices, and “releases” such a logical volume so as to enable use by other host devices. Read/write type requests are requests indicating data is to be written to a logical volume, or that data is to be read from a logical volume. “Enabling use by” can also be termed “releasing usage rights”. The disk control software 1050a is software which operates as a device driver of the storage device system 20A. The disk control software 1050a may, for example, receive internal requests from cluster software, convert internal requests into commands (for example, SCSI commands) in a format which can be interpreted by the storage device system 20A, and issues requests (hereafter “I/O requests”) comprising these commands. Further, the disk control software 1050a, upon receiving data indicating an anomaly status as the processing result of an issued I/O request, executes retry processing to re-issue the same I/O request as the above previously issued I/O request. This retry processing is performed a number of retry times indicated by the number-of-retries information 2 registered, for example, in memory 320 (or in another storage device). Specifically, for example, the disk control software 1050a reads the number-of-retries information 2, ascertains the number of retries indicated by the number-of-retries information 2, and each time retry processing is performed, counts the number of times retry processing is performed, and when the count result matches the number of retries indicated by the number-of-retries information 2, notifies the cluster software 1040a of the I/O request processing result. When a result relating to an anomaly is received as the processing result of an I/O request, the cluster software 1040a initiates fail-over processing. The arbitration emulation software 1060a is software to execute control (in this example, for convenience, called “arbitration”) to prevent a split-brain state in which the host devices HA1, HB1 forming the cluster operate separately. The arbitration emulation software 1060a uses the arbitration disk 211a within the storage device system 20A to perform arbitration. The storage device system 20A can copy data within the arbitration disk 211a to the arbitration disk 211b in the storage device system 20B, either actively (in other words, using a push method) or in response to a request from the storage device system 20B (in other words, using a pull method). The remote copy control software 1070a is software for controlling remote copying. The remote copy control software 1070a can, for example, creates and deletes copy pairs for remote copying, and swap the copy source and copy target of a copy pair. In more detail, for example, a direct instruction may be performed by the remote copy control software 1070a, and an indirect instruction may be performed by the arbitration emulation software 1060a. In still greater detail, the remote copy control software 1070a can for example become the application program interface (API) of certain software (not shown) installed on the host device HA1 to issue instructions to the storage device system 20A, and the arbitration emulation software 1060a can issue instructions to the storage device system 20A via the remote copy control software 1070a as the API. In this example, two-stage arbitration is performed. To explain this briefly, in the first arbitration, arbitration using an arbitration disk is performed between two or more host devices within each site, so that an arbitration winner is determined within each site. In the second arbitration, arbitration is performed among two or more host devices which have each won arbitration within their sites, using arbitration disks 211a, 211b of copy pairs for remote copying, and the host device which wins this arbitration is the final winner. Below, one specific processing flow of this two-stage arbitration is explained. In this case, the first arbitration is performed by the cluster software 1040a, and the second arbitration is performed by the arbitration emulation software 1060a. In the first arbitration, by for example issuing an I/O request having a SCSI command to the logical volume 212a, two or more host devices HA1 through HAn perform a lock state operation using a lock (Reserve, Release, Reset) command described below, or verify a particular sector using a read/write (Read, Write) command, and as a result the host device which is ultimately able to secure the logical volume 212a becomes the arbitration winner (strictly seeking, bus reset is not a SCSI command, but for convenience is included). Information relating to which host device has succeeded in securing the logical volume 212a (hereafter called “arbitration disk control information” 6) is for example registered in shared memory 260 by the host device I/F 230 of the storage device system 20A. The host device I/F 230, by referencing the arbitration disk control information 6, can refuse requests to access the logical volume 212a from an arbitration loser (host device). This first arbitration is also performed at other sites. However, this operation alone would result in the following problem. Because the state of securing of one of the logical volumes 212a is not reflected in the other logical volume 212b, a logical volume forming a copy pair can be secured at each site, and consequently there is an arbitration winner (host device) at each site, as a result of which a plurality of arbitration winners exist in the cluster system. In order to avoid this, in the present example the final arbitration winner is determined based on the copy pair state. More specifically, suppose that for example a logical volume the copy state of which is “copy source state” is in a state of being secured by a host device which has secured the logical volume; a logical volume the copy state of which is “copy target state” is in a state of being secured by another host device different from the host device which has secured the logical volume; and a logical volume the copy state of which is “copy interrupted” is in a state of not being secured by any host device. As a result, the host device which has secured the logical volume in the copy source state becomes the final arbitration winner, and the host device which had secured the logical volume in the copy target state recognizes that the latter logical volume has been secured by another host device. Information as to the copy state of the volume, what volumes form copy pairs and similar (for example, information indicating contents similar to the remote copy control information 4) is also comprised by the arbitration disk control information 6, and the host device I/F 230 may for example, by referencing this information 6, determine which volume is in what copy state. In this way, two-stage arbitration is performed combining SCSI commands and remote copy control. FIG. 3 shows in detail the software configuration of the host device HA1. The arbitration emulation software 1060a comprises the I/O request reception portion 3000, I/O request processing portion 3010 and fault recovery detection portion 3020. In the memory 320 of the host device HA1 (or in another storage area) are prepared an I/O request queue 3500; fault detection flag 3510; fault information 3520; SCSI command type judgment table 3530; I/O return value judgment table 3540; SCSI command return value judgment table 3550; remote copy control return value judgment table 3560; and I/O-SCSI command return value conversion table 3570. At least one among these is used, as appropriate, as at least one among the I/O request reception portion 3000, I/O request processing portion 3010, and fault recovery detection portion 3020. The I/O request queue 3500 is a mechanism to store I/O requests issued to the logical volume (hereafter the “arbitration volume” 212a) of the arbitration disk 211a, and is for example configured as a list. The fault detection flag 3510 is a flag which records the occurrence of a fault in the arbitration disk 211a (hereafter called a “disk fault”). The fault detection flag 3510 is set to “ON” when a disk fault is detected, and is set to “OFF” when no disk fault is detected. The fault information 3520 is information relating to detected disk faults, and indicates, for example, details of the anomaly status set for I/O return values and SCSI command return values from the arbitration disk 212a. Here an “I/O return value” is received from the storage device system 20A as information indicating the result of processing of the I/O request itself, and is received for all I/O requests issued, regardless of whether the I/O request comprises a SCSI command. A “SCSI command return value” is received from the storage device system 20A as information indicating the result of processing of a SCSI command comprised by an I/O request, and is received only in cases where an I/O request comprising a SCSI command is issued. That is, in this example, when the storage device system 20A (for example, the host device I/F 230) receives a SCSI arbitration I/O request, an I/O return value and SCSI command return value indicating the results of processing of the I/O request and the SCSI command comprised thereby respectively can be transmitted to the host device HA1. The SCSI command type judgment table 3530 is a table in which is registered information relating to criteria for judging SCSI command types. More specifically, the SCSI command type judgment table 3530 is a table which stores, for example, criteria for judging whether a SCSI command comprised by an I/O request belongs to the lock type or to the read/write type. The I/O return value judgment table 3540 is a table in which is registered information relating to criteria for how I/O return value contents should be judged. More specifically, the I/O return value judgment table 3540 is a table which stores, for example, criteria for judging whether an I/O return value is associated with normal status, anomaly status, or conflict. The SCSI command return value judgment table 3550 is a table in which is registered information relating to criteria for how SCSI command return value contents should be judged. More specifically, the SCSI return value judgment table 3550 is a table which stores, for example, criteria for judging whether a SCSI command return value is associated with normal status, anomaly status, or conflict. The remote copy control return value judgment table 3560 is a table in which is registered information relating to criteria for how remote copy control return value contents should be judged. More specifically, the remote copy control return value judgment table 3560 is a table which stores, for example, criteria for judging whether a remote copy control return value is associated with normal status, anomaly status, or conflict. A “remote copy control return value” is information received from the storage device system 20A as the result of remote copy pair control processing, described below. The I/O-SCSI command return value conversion table 3570 is a table which stores criteria for judging which I/O return value and SCSI command return value to output, when a remote copy control return value is received. The I/O request reception portion 3000 receives an I/O request issued to the arbitration volume 212a from the disk control software 1050a, and performs processing to store the I/O request at a prescribed position (for example, at the end) of the I/O request queue 3500. FIG. 10 shows an example of the processing flow of this I/O request reception portion 3000. The I/O request processing portion 3010 extracts one I/O request at a time from the I/O request queue 3500, and performs the two-stage arbitration processing described above. In two-stage arbitration processing, it is necessary to communicate with the remote copy control software 1070a, and a software interface 3030 is used for this communication. As the software interface 3030, for example, a method employing an interface provided by the operating system, not shown, or a method in which data exchange is performed via memory which can be shared among the software modules, can be adopted. FIG. 11 shows an example of the processing flow of the I/O request processing portion 3010. The fault recovery detection portion 3020 executes a separate thread when a disk fault is detected in processing by the I/O request processing portion 3010, and investigates the state of the arbitration disk 1030a with a certain timing (for example, periodically, or irregularly), until disk fault recovery is detected. The remote copy control software 1070 performs remote copy pair control of the arbitration disk 211a of an arbitration volume 212a which is one portion of a copy pair. Details of control of the remote copy pair differ depending on details of communication with the I/O request processing portion 3010 via the software interface 3030. Also, for example the logical volume paired with an arbitration volume 212a, or whether an arbitration volume 212a is a copy source or a copy target, can be registered in the remote copy control information 6 (for example, existing in a prescribed storage area), so that by referencing this remote copy information 6, these details can be determined. FIG. 4 shows an example of the configuration of fault information 3520. The fault information 3520 comprises one or more I/O request identifiers, a fault I/O return value associated with each I/O request identifier, fault SCSI command return values, and fault remote copy control return values. I/O request identifiers are identifiers of I/O requests associated with I/O return values or SCSI return values with anomaly status (in other words, I/O requests which were not processed normally), and may be for example the value of a pointer to the I/O request (for example, 0×1234). When there exist no I/O request identifiers in the fault information 3520, a prescribed initial value (for example, NULL) is set in the fault information 3520 as an I/O request identifier. A fault I/O return value is the value set as the I/O return value itself when an I/O return value is judged to have anomaly status, and may be, for example, “TIMEOUT”, “DISCONNECT”, “BUSY”, or similar. When there exist no fault I/O return values in the fault information 3520, a prescribed initial value (for example, “SUCCESS”) is set as a fault I/O return value. A fault SCSI command return value is the value set as the SCSI return value itself when a SCSI command return value is judged to have anomaly status, and may be, for example, “TIMEOUT”, “DISCONNECT”, “BUSY”, or similar. When there exist no fault SCSI command return values in the fault information 3520, a prescribed initial value (for example, “GOOD”) is set as a fault SCSI command return value. A fault remote copy control return value is the remote copy control return value itself, when a remote copy control return value is judged to have anomaly status, and may be, for example, “TIMEOUT”, “DISCONNECT”, “BUSY”, or similar. When there exist no fault remote copy control return values in the fault information 3520, a prescribed initial value (for example, “GOOD”) is set as a fault remote copy control reutnr value. FIG. 5 shows an example of the configuration of a SCSI command type judgment table 3530. The SCSI command types of each of a plurality of SCSI commands are registered in the SCSI command type judgment table 3530. SCSI commands include, for example, Reserve, Release, Reset, Read, and Write; SCSI command types are lock the type and read/write type. The table 3530 shown in FIG. 5 indicates that the SCSI commands Reserve, Release and Reset belong to the lock SCSI command type. The table 3530 also shows that the SCSI commands Read and Write belong to the read/write SCSI command type. FIG. 6 shows an example of the configuration of an I/O return value judgment table 3540. A plurality of types of I/O return values, and I/O return value judgment results associated with the plurality of types of I/O return values, are registered in the I/O return value judgment table 3540. Below, an example of this association is explained, but associations are not thereto limited. The I/O return value “SUCCESS” signifies that the I/O request issued to the arbitration volume 212a (hereafter abbreviated to “arbitration I/O request”) was processed normally. The I/O return value “TIMEOUT” signifies that processing of the arbitration I/O request was delayed, resulting in a timeout. The I/O return value “DISCONNECT” signifies that the arbitration I/O request could not be passed (for example, the arbitration I/O request could not be stored in the cache memory 250 of the storage device system 20A). The I/O return value “BUSY” signifies that, because the arbitration disk 211a was in a busy state, the arbitration I/O request could not be processed. An I/O return value judgment result is the result of judgment of the status associated with an I/O return value; the status may be, for example, normal status, anomaly status, or conflict. Normal status signifies that processing of the arbitration I/O request ended normally. Anomaly status signifies that an anomaly occurred in processing of the arbitration I/O request. Conflict signifies that because the arbitration volume 212a is reserved by another host device (that is, has been secured), the arbitration I/O request could not be processed. According to the I/O return value judgment table 3540, when an I/O return value is “SUCCESS”, the I/O return value is judged to be associated with normal status. When an I/O return value is “TIMEOUT” or “DISCONNECT”, the I/O return value is judged to be associated with anomaly status. When the I/O return value is “BUSY”, the I/O return value is judged to have status of either anomaly or conflict, and further judgment using the SCSI command return value judgment table 3550 becomes necessary. FIG. 7 shows an example of the configuration of a SCSI command return value judgment table 3550. A plurality of types of SCSI command return values, and SCSI command return value judgment results associated with each of the plurality of types of SCSI command return values, are registered in the SCSI command return value judgment table 3550. An arbitration I/O request may or may not comprise a SCSI command; but when either case is possible, “arbitration I/O request” is used, whereas in the case of an arbitration I/O request comprising a SCSI command, “SCSI arbitration I/O request” is used. The SCSI command return value “GOOD” signifies that the SCSI arbitration I/O request was processed normally. The SCSI command return value “TIMEOUT” signifies that processing of the SCSI arbitration I/O request was delayed, so that a timeout occurred. The SCSI command return value “DISCONNECT” signifies that the SCSI arbitration I/O request could not be passed (for example, the SCSI arbitration I/O request could not be stored in the cache memory 250 of the storage device system 20A). The SCSI command return value “BUSY” signifies that because the arbitration disk 211a was in the busy state, the SCSI arbitration I/O request could not be processed. The SCSI command return value “CONFLICT” signifies that because the arbitration volume 212a was reserved by another host device (that is, was secured), the SCSI arbitration I/O request could not be processed. A SCSI command return value judgment result is a result of judgment the status associated with a SCSI command return value; the status may be, for example, normal status, anomaly status, or conflict. Normal status signifies that processing of the SCSI arbitration I/O request ended normally. Anomaly status signifies that an anomaly occurred in processing of the SCSI arbitration I/O request. Conflict signifies that because the arbitration volume 212a is reserved by another host device (that is, has been secured), the SCSI arbitration I/O request could not be processed. According to the SCSI command return value judgment table 3550, when a SCSI command return value is “GOOD”, the SCSI command return value is judged to be associated with normal status. When a SCSI command return value is “TIMEOUT”, “DISCONNECT” or “BUSY”, the SCSI command return value is judged to have anomaly status. When a SCSI command return value is “CONFLICT”, the SCSI command return value is judged to be conflict. The above is an example of the configuration of a SCSI command return value judgment table 3550; however, the association of SCSI command return values and SCSI command return value judgment results is not limited to the above example. FIG. 8 shows an example of the configuration of a remote copy control return value judgment table 3560. A plurality of types of remote copy control return values, and remote copy control return value judgment results associated with each of the plurality of types of remote copy control return values, are registered in the remote copy control return value judgment table 3560. Below, an example of such associates is explained, but these associations are not limited to the example below. The remote copy control return value “GOOD” signifies that remote copy control processing by the remote copy control software 1070a ended normally. The remote copy control return value “TIMEOUT” signifies that a delay occurred in remote copy control processing, so that a timeout occurred. The remote copy control return value “DISCONNECT” signifies that the arbitration disk 211a (or arbitration volume 212a) of the remote copy control could not be found. The remote copy control return value “BUSY” signifies that the arbitration disk 211a for remote copy control was in the busy state, and processing could not be performed. The remote copy control return value “CONFLICT” signifies that remote copy control processing ended normally, and that the copy state of the arbitration volume 212a was the “copy target state” (that is, that the arbitration volume 212a was the copy target logical volume). A remote copy control return value judgment result is the result of judgement of the status associated with a remote copy control return value; the status may be, for example, normal status, anomaly status, or conflict. Normal status signifies that remote copy control processing ended normally. Anomaly status signifies that an anomaly occurred during remote copy control processing. Conflict signifies that remote copy pair control processing ended normally, and that the arbitration volume 212a is a copy target logical volume. According to the remote copy control return value judgment table 3560, when a remote copy control return value is “GOOD”, the remote copy control return value is judged to have normal status. When the remote copy control return value is “TIMEOUT”, “DISCONNECT” or “BUSY”, the remote copy control return judgment value is judged to have anomaly status. When the remote copy control return value is “CONFLICT”, the remote copy control return value is judged to have conflict status. FIG. 9 shows an example of the configuration of an I/O-SCSI command return value conversion table 3570. The I/O-SCSI command return value conversion table 3570 is a table which stores criteria for the output of I/O return values and SCSI command return values when any remote copy control return value such as described above has been received. Below, an example of these criteria is explained, but the criteria are not limited to the following example. In the table 3570 a remote copy control return value of “GOOD” is associated with the converted I/O return value “SUCCESS” and with the converted SCSI command return value “GOOD”. This signifies that, when “GOOD” is detected as the remote copy control return value, “SUCCESS” is output as the I/O return value of the I/O request comprising a SCSI command, and “GOOD” is output as the SCSI command return value of the I/O request. Also, in the table 3570 a remote copy control return value of “TIMEOUT” is associated with the converted I/O return value “TIMEOUT” and with the converted SCSI command return value “TIMEOUT”. This signifies that, when “TIMEOUT” is detected as the remote copy control return value, “TIMEOUT” is output as the I/O return value of the I/O request comprising a SCSI command, and “TIMEOUT” is output as the SCSI command return value of the I/O request. Also, in the table 3570 a remote copy control return value of “DISCONNECT” is associated with the converted I/O return value “DISCONNECT” and with the converted SCSI command return value “DISCONNECT”. This signifies that, when “DISCONNECT” is detected as the remote copy control return value, “DISCONNECT” is output as the I/O return value of the I/O request comprising a SCSI command, and “DISCONNECT” is output as the SCSI command return value of the I/O request. Also, in the table 3570 a remote copy control return value of “BUSY” is associated with the converted I/O return value “BUSY” and with the converted SCSI command return value “BUSY”. This signifies that, when “BUSY” is detected as the remote copy control return value, “BUSY” is output as the I/O return value of the I/O request comprising a SCSI command, and “BUSY” is output as the SCSI command return value of the I/O request. Also, in the table 3570 a remote copy control return value of “CONFLICT” is associated with the converted I/O return value “BUSY” and with the converted SCSI command return value “CONFLICT”. This signifies that, when “CONFLICT” is detected as the remote copy control return value, “BUSY” is output as the I/O return value of the I/O request comprising a SCSI command, and “CONFLICT” is output as the SCSI command return value of the I/O request. Below, the flow of processing performed using the tables explained in FIG. 5 through FIG. 9 is explained, referring to FIG. 10 through FIG. 13. If FIG. 3 is referenced as appropriate to the following explanation, the overall flow of processing in the cluster system of this example can be better understood. FIG. 10 shows an example of the processing flow of an I/O request reception portion 3000. In the following explanation, steps representing operation are abbreviated to “S”. Suppose that the cluster software 1040a issues to the disk control software 1050a an internal request indicating a request to the arbitration volume 212a. In this case, the disk control software 1050a converts the internal request into a SCSI command, generates an arbitration I/O request comprising this SCSI command (that is, a SCSI arbitration I/O request), and issues this SCSI arbitration I/O request to the arbitration emulation software 1060a. The I/O request reception portion 3000 accepts I/O requests, and receives SCSI arbitration I/O requests from the disk control software 1050a (S10000). The I/O request reception portion 3000 stores received SCSI arbitration I/O requests at the end (or in another position) of the I/O request queue 3500 (S10010). Then, the I/O request reception portion 3000 again accepts I/O requests. FIG. 11 shows an example of the processing flow of the I/O request processing portion 3010. The I/O request processing portion 3010 extracts one I/O request from a prescribed position (for example, the beginning) of the I/O request queue 3500 (hereafter, the extracted I/O request is called the “SCSI arbitration I/O request”) (S11000). However, when there is no I/O request stored in the I/O request queue 3500, the I/O request processing portion 3010 waits until a new I/O request is stored. Next, the I/O request processing portion 3010 references the fault detection flag 3510 and judges the state of the fault detection flag 3510 (S11010). If as a result of the judgment of S11010 the fault detection flag 3510 is detected to be “OFF” (that is, if no disk fault occurrence is detected), the I/O request processing portion 3010 performs the processing of step S11020. That is, the I/O request processing portion 3010 references the SCSI command type judgment table 3530 (see FIG. 5), and judges the type of the SCSI command comprised by the SCSI arbitration I/O request. More specifically, if the I/O request processing portion 3010 detects the SCSI command comprised by the SCSI arbitration I/O request to be “Reserve”, “Release” or “Reset”, the SCSI command type is judged to be a lock type, whereas if the SCSI command is detected to be “Read” or “Write”, the SCSI command type is judged to be the read/write type. The subsequent flow of processing differs greatly depending on the result of this judgment S11020. Below, explanations are given for cases in which the result of the judgment of S11020 is the lock type and the read/write type. (1) Case in which the lock type is judged in S11020 In S11020, when the SCSI command type is judged to be the lock type, the I/O request processing portion 3010 transmits the SCSI arbitration I/O request to the storage device system 20A (S11030). As a result, the I/O request processing portion 3010 receives the SCSI arbitration I/O request processing result from the storage device system 20A (S11040). This received processing result comprises the I/O return value and SCSI return value. The I/O request processing portion 3010 uses the I/O return value received in step S11040 and references the I/O return value judgment table 3540 (see FIG. 6) to perform an I/O return value judgment to determine the status of the I/O return value, and moreover uses the SCSI command return value received in step S11040 and references the SCSI command return value judgment table 3550 (see FIG. 7) to perform a SCSI command return value judgment to determine the status of the SCSI command return value (S11050). If the I/O request processing portion 3010 detects that the I/O return value is “SUCCESS” and the SCSI return value is “GOOD”, then the status is judged to be normal. If the I/O request processing portion 3010 detects that the I/O return value is either “TIMEOUT”, “DISCONNECT” or “BUSY”, and that the SCSI command return value is either “TIMEOUT”, “DISCONNECT” or “BUSY”, then the status is judged to be the anomaly status. If the I/O request processing portion 3010 detects that the I/O return value is “BUSY” and that the SCSI command return value is “CONFLICT”, then the status is judged to be conflict. In S11050, if status is judged to be conflict, the I/O request processing portion 3010 returns the I/O return value and SCSI return value received in S11040 to the disk control software 1050a as the result of processing of the SCSI arbitration I/O request (S11100). If in S11050 the status is judged to be anomaly status, the I/O request processing portion 3010 accesses the fault detection flag 3510, and updates the state of the fault detection flag 3510 from “OFF” to “ON” (S11110). By this means the occurrence of a disk fault is recorded in a storage area of the host device HA1 (for example, in an area of memory 320). Also, the I/O request processing portion 3010 records, in the fault information 3520 (see FIG. 4), the identifier (for example, pointer value) of the SCSI arbitration I/O request the status of which was judged to be anomaly status, the received I/O return value (that is, the fault I/O return value), and the received SCSI return value (that is, the fault SCSI return value) (S11120). Further, the I/O request processing portion 3010 causes the fault recovery detection portion 3020 to start another thread (S11130). By this means, monitoring to determine whether there has been recovery from the disk fault is begun. Finally, the I/O request processing portion 3010 returns, to the disk control software 1050a, the I/O return value and SCSI return value received in S11040, as the SCSI arbitration I/O request processing result (S11100). If in S11050 the status is judged to be normal status, the I/O request processing portion 3010 transmits a remote copy control request to the remote copy control software 1070a via the software interface 3030 (S11060), and by this means effects remote copy pair control. The transmitted remote copy control request comprises a SCSI command, and the remote copy control software 1070a performs remote copy pair control according to the type of this SCSI command. The I/O request processing portion 3010 receives the control result, comprising a remote copy control return value, from the remote copy control software 1070a (S11070). The I/O request processing portion 3010 references the I/O-SCSI command return value conversion table 3570 (see FIG. 9), and extracts the converted I/O return value and converted SCSI return value corresponding to the received remote copy control return value from the I/O-SCSI command return value conversion table 3570 (S11080). The I/O request processing portion 3010 then uses the converted I/O return value and converted SCSI return value thus acquired to perform judgment processing similar to that of S11050 (S11090). If in S11090 the status is judged to be anomaly status, the I/O request processing portion 3010 performs the processing of the above-described S11110 and later. However, the I/O request processing portion 3010 has received the remote copy control return value in S11070, and so in S11120 the received remote copy control return value is also registered in the fault information 3520. Then, in S11100, the I/O request processing portion 3010 returns the I/O return value and SCSI return value acquired in S11080 to the disk control software 1050a. If in S11090 the status is judged to be normal or conflict, the I/O request processing portion 3010 returns, to the disk control software 1050a, the I/O return value and SCSI return value acquired in S11080, as the SCSI arbitration I/O request processing result (S11100). The above is the flow of processing when in S11020 the type is judged to be the lock type. Next, the flow of processing when in S11020 the type is judged to be read/write is explained. (2) Case in which the read/write type is judged in S11020 If in S11020 the SCSI command type is judged to be read/write, the I/O request processing portion 3010 transmits to the remote copy control software 1070a a remote copy control request comprising the SCSI command, similarly to S11060 above (S11150). Then, the I/O request processing portion 3010 receives from the remote copy control software 1070a a control result comprising the remote copy control return value (S11160). The I/O request processing portion 3010 uses the remote copy control return value received in step S11160 and references the remote copy control return value judgment table 3560 (see FIG. 8) to perform remote copy control return value judgment, to determine the status associated with the remote copy control return value (S11170). If in S11170 the status is judged to be anomaly or conflict, the I/O request processing portion 3010 uses the remote copy control return value received in S11160 to perform the processing of the above-described S11080 and later. In S11100, the I/O request processing portion 3010 returns to the disk control software 1050a the I/O return value and SCSI return value acquired in S11080. Also, if in S11090 the status is judged to be anomaly status, in S11120 the I/O request processing portion 3010 registers in the fault information 3520 the remote copy control return value (other than “GOOD”) received in S11160. If in S11170 the status is judged to be normal, the I/O request processing portion 3010 transmits the SCSI arbitration I/O request to the storage device system 20A (S11180), and then receives the processing result for the SCSI arbitration I/O request from the storage device system 20A (S11190). The I/O request processing portion 3010 uses the I/O return value and SCSI return value comprised by the received processing result to perform the processing of the above-described S11090 and later. For example, in S11100 the I/O request processing portion 3010 returns the I/O return value and SCSI return value received in S11190 to the disk control software 1050a. Also, when for example in S11090 the status is judged to be anomaly, in S11120 the I/O request processing portion 3010 registers the remote copy control return value “GOOD” received in S11160 in the fault information 3520. The above is an explanation of the flow of processing when in S11020 the type is judged to be read/write. If in S11010 the fault detection flag 3510 is detected to be “ON” (that is, if the occurrence of a disk fault is detected), the I/O request processing portion 3010 performs the processing of step S11140. That is, the I/O request processing portion 3010 acquires from the fault information 3520 the fault I/O return value and fault SCSI return value corresponding to the identifier comprised by the SCSI arbitration I/O request acquired in S11000, and sets these acquired values in the processing result returned to the disk control software 1050a (S11140). Then the I/O request processing portion 3010 transmits this processing result (that is, data comprising the fault I/O return value and fault SCSI return value acquired in S11140) to the disk control software 1050a (S11100). FIG. 12 shows an example of the processing flow of the fault recovery detection portion 3020. The fault recovery detection portion 3020 is started through, for example, the processing in S11130 of the I/O request processing portion (see FIG. 11), and can initiate the following processing. The fault recovery detection portion 3020 first makes a judgment to determine the fault remote copy control return value in the fault information 3520 (S12000). In S12000, a fault remote copy control return value of “GOOD” indicates that some fault relating to the arbitration disk 211a has occurred. In this case, the fault recovery detection portion 3020 creates a SCSI arbitration I/O request to detect recovery from the fault of the arbitration disk 211a (S12010). As the newly created SCSI arbitration I/O request, for example, an arbitration I/O request comprising a “Reserve” SCSI command can be employed. Also, the newly created SCSI arbitration I/O request (that is, the SCSI arbitration I/O request scheduled to be transmitted) can for example be registered in a storage area (for example, memory 320) of the host device HA1. The fault recovery detection portion 3020 transmits the created SCSI arbitration I/O request to the storage device system 20A (S12020), and then receives the processing result from the storage device system 20A (S12030). The fault recovery detection portion 3020 uses the I/O return value and SCSI return value comprised by the received processing result to perform judgment processing similar, for example, to S11050 (see FIG. 11) (S12040). In S12040, a judgment that the status is normal or conflict indicates that there has been recovery from the disk fault. In this case, the fault recovery detection portion 3020 releases the used SCSI arbitration I/O request (for example, erases the SCSI arbitration I/O request created in S12010 from the prescribed storage area) (S12050), changes the state of the fault detection flag 3510 from “ON” to “OFF” (S12060), erases the contents of the fault information 3520 (for example, by overwriting with an initial value) (S12070), and ends processing. On the other hand, a judgment in S12040 that the status is anomaly indicates that the disk fault continues. In this case, the fault recovery detection portion 3020 releases the used SCSI arbitration I/O request (S12080), and after performing wait processing (S12090) again performs the processing of S12010. Wait processing is processing performed after the release of a used SCSI arbitration I/O request to maintain a standby state for a fixed length of time (for example, three seconds) until a SCSI arbitration I/O request is again created. The standby time may be a fixed value, or may be changed by the user. In S12000, a fault remote copy control return value other than “GOOD” indicates that some fault relating to remote copy control, rather than a disk fault, has occurred (for example, occurrence of a fault in the remote copy control software 1070a). In this case, the fault recovery detection portion 3020 creates a remote copy control request and transmits the request to the remote copy control software 1070a (S12100). The contents of the transmitted remote copy control request may, for example, confirm the copy state of the remote copy pair. The fault recovery detection portion 3020 receives the result from the remote copy control software 1070a (S12110), and using the remote copy control return value comprised by the received result, performs a judgment similar for example to that of S11170 (see FIG. 11) (S12120). In S12120, if the status is judged to be normal, the fault recovery detection portion 3020 performs the processing of S12060 and later, but if the status is judged to be anomaly status, waits for a fixed length of time (for example, three seconds) (S12130) and then again performs the processing of S12100. The contents of the remote copy control request transmitted in S12100 confirm the state of the remote copy pair, and so the remote copy control return value is never set to conflict. FIG. 13 shows an example of the processing flow of the remote copy control software 1070a. The remote copy control software 1070a receives a remote copy control request from the I/O request processing portion 3010 or from the fault recovery detection portion 3020 (S13000). Next, the remote copy control software 1070a executes remote copy control according to the remote copy control request received (S13010). Specifically, the remote copy control software 1070a for example can execute the processing of any of the following (1) through (3): (1) processing to confirm the copy state of the arbitration volume 212a which is one logical volume of a copy pair; (2) when the arbitration volume 212a is a copy source logical volume, remote copying, such as for example causing the storage device system 20A to execute processing to store the entirety or a portion of the data stored in the arbitration volume 212a (for example, the difference between existing data and newly written data) in the copy target volume 212b via the device I/F 240; and, (3) processing to invert the copy states of the arbitration volumes 212a and 212b, and accompanying this to transpose the data in the arbitration volume 212a and the data in the arbitration volume 212b. The remote copy control software 1070a generates a remote copy control return value according to the remote copy control processing result, and transmits processing result data comprising this value to the transmission source of the remote copy control request (the I/O request processing portion 3010 or the fault recovery detection portion 3020) (S13020). One of the above flows of processing may for example be summarized as follows. (1) Case in which a SCSI arbitration I/O request comprising a lock-type SCSI command is output The arbitration emulation software 1060a, while receiving SCSI arbitration I/O requests from the device control software 1050a, outputs the SCSI arbitration I/O requests to the storage device system 20A (for example, attempting to win the first arbitration). When in response an I/O return value or SCSI command return value with normal status is received from the storage device system 20A (when for example a response to the effect that the first arbitration has been won is received), the arbitration emulation software 1060a transmits a remote copy control request to the remote copy control software 1070a (for example, attempting to win the second arbitration also). The remote copy control software 1070a, upon for example failing to put the arbitration volume 212a into the copy source state, outputs a remote copy control return value with anomaly status (for example, outputs a response to the effect that the second arbitration has been lost). The arbitration emulation software 1060a receives the remote copy control return value, acquires the I/O return value and SCSI command return value corresponding to the remote copy control return value, and, if the acquired I/O return value and SCSI command return value have anomaly status, turns the fault detection flag 3510 to “ON” and writes the acquired I/O return value and SCSI command return value to the fault information 3520. (2) Case in which a SCSI arbitration I/O request comprising a read/write-type SCSI command is output The arbitration emulation software 1060a, while receiving SCSI arbitration I/O requests from the device control software 1050a, transmits a remote copy control request to the remote copy control software 1070a. When for example remote copying fails, the remote copy control software 1070a outputs a remote copy control return value with anomaly status. The arbitration emulation software 1060a receives the remote copy control return value, acquires the I/O return value and SCSI command return value corresponding to the remote copy control return value, and, if the acquired I/O return value and SCSI command return value correspond to anomaly status, turns the fault detection flag 3510 to “ON” and writes the acquired I/O return value and SCSI command return value to the fault information 3520. According to the above-described first example, arbitration emulation software 1060a intervenes between the disk control software 1050a and storage device system 20A (the arbitration emulation software 1060a may be incorporated into the disk control software 1050a). The arbitration emulation software 1060a receives SCSI arbitration I/O requests from the disk control software 1050a and transmits these requests to the storage device system 20A, and receives the processing results of the SCSI arbitration I/O requests (data comprising the I/O return value and SCSI command return value) from the storage device system 20A. The arbitration emulation software 1060a judges whether an anomaly has occurred from the I/O return value and SCSI command return value comprised by the received processing result, and if it is judged that an anomaly has occurred, sets the state of the fault detection flag 3510 to “ON”, stores the I/O return value and SCSI command return value at this time (the fault I/O return value and fault SCSI command return value) to a prescribed storage area, and transmits the fault I/O return value and fault SCSI return value to the disk control software 1050a. The disk control software 1050a, upon receiving a fault I/O return value and fault SCSI return value, performs retry processing, that is, retransmits the previously transmitted SCSI arbitration I/O request. The arbitration emulation software 1060a, upon receiving the same SCSI arbitration I/O request as when an anomaly was judged to have occurred during the period in which the fault detection flag 3510 is in the “ON” state, reads the fault I/O return value and fault SCSI command return value from a prescribed storage area immediately, without transmitting the I/O request to the storage device system 20A (for example, discarding the I/O request), and returns these to the disk control software 1050a. From the standpoint of the disk control software 1050a, the fault I/O return value and fault SCSI command return value are received immediately after retransmitting the SCSI arbitration I/O request as retry processing. Hence even if some fault occurs in remote copy control and a remote copy control return value is issued in response, the fault detection flag 3510 is set to the “ON” state, and similar processing is performed. By this means, even if retry processing is performed a plurality of times by the disk control software 1050a, the plurality of retry processing attempts ends more quickly (for example, after a much shorter length of time) than if SCSI arbitration I/O requests were transmitted to the storage device system 20A. Hence the cluster software 1040a can receive an error report from the disk control software 1050a more quickly (for example, even if retry processing is performed a plurality of times, the error report can be received with substantially the same timing, or nearly the same timing, as if retry processing had not been performed even once), and consequently fail-over processing can be initiated more quickly. Below, a second example of an embodiment of the invention is explained. In the following, explanations of portions which are redundant with the first example are omitted or abbreviated, and the explanation focuses primarily on differences with the first example (and similarly for the third and subsequent examples as well as for the second example). FIG. 14 shows an example of the processing flow of the I/O request reception portion 3000 in the second example of an embodiment of the invention. The I/O request reception portion 3000 receives a SCSI arbitration I/O request from the disk control software 1050a (S14000), and prior to storing the I/O request in the I/O request queue 3500, references the fault detection flag 3510 and judges the state of the flag (S14010). If in S14010 the fault detection flag 3510 is judged to be in the “OFF” state, the I/O request reception portion 3000 stores the received SCSI arbitration I/O request in a prescribed position (for example, at the end) of the I/O request queue 3500 (S14020). If on the other hand in S14010 the fault detection flag 3510 is judged to be in the “ON” state, the I/O request reception portion 3000 acquires the fault I/O return value and fault SCSI command return value corresponding to the identifier of the received SCSI arbitration I/O request from the fault information 3520 (S14030), and transmits these to the disk control software 1050a (S14040). As described above, in this second example the I/O request reception portion 3000 judges the state of the fault detection flag 3510, and if the flag state is judged to be “ON”, returns the fault I/O return value and fault SCSI command return value to the disk control software 1050a. Hence the I/O request processing portion 3010 need no longer perform the processing of the above-described S11010 and S11140 (see FIG. 11) (other processing is performed similarly to the first example). In a third example, when a prescribed module (for example, a module of the operating system) detects a change in device information through Plug-and-Play (hereafter “PnP”), processing to acquire the device information is executed automatically by the operating system. Device information is for example information relating to the configuration of a storage device system 20A, and may for example be information such as the capacity of a logical volume on physical storage devices having certain attributes (such as, for example, high or low reliability). Device information is for example stored in the shared memory 260 of the storage device system 20A. A change in this device information can be recognized through, for example, notification by the storage device system 20A. When acquisition of device information is initiated, the fault recovery detection portion 3020 is started, and the following processing is performed by the fault recovery detection portion 3020. FIG. 15 shows an example of the processing flow of the fault recovery detection portion 3020 in the third example. The fault recovery detection portion 3020 first judges the value of the fault remote copy control return value in the fault information 3520 (S16000). In this step S16000, if it is judged that the fault remote copy control return value is “GOOD”, the fault recovery detection portion 3020 generates a device information acquisition I/O request and transmits this to the storage device system 20A (S16010), and then receives the processing report for this I/O request from the storage device system 20A (S16020). As the transmitted device information acquisition I/O request, for example, a “Query Device Relations” PnP I/O request can be used. The fault recovery detection portion 3020 uses the I/O request comprised by the received processing result to perform judgment processing similar for example to that of S11050 (see FIG. 11) (S16030). In S16030, when status is judged to be normal, the fault recovery detection portion 3020 changes the state of the fault detection flag 3510 from “ON” to “OFF” (S16040), erases the contents of the fault information 3520 (by for example overwriting with an initial value) (S16050), and ends processing. In S16030, when the status is judged to be anomaly, the fault recovery detection portion 3020 ends processing. If in S16000 the fault remote copy control return value is judged to be other than “GOOD”, the fault recovery detection portion 3020 performs processing similar to the above-described S12100 through S12120. In S12120, when the status is judged to be anomaly, the fault recovery detection portion 3020 ends processing. In a fourth example, an example is described of a system in which the cluster software 1040a, by performing resource online processing to put the arbitration disk 211a (a cluster resource) into a usable state, detects fault recovery. Here “cluster resource” is a resource managed by the cluster (for example, a physical storage device or other hardware, or a database management system or other program). FIG. 16 shows an example of the processing flow of the fault recovery detection portion 3020 in the fourth example. For example, the fault recovery detection portion 3020 receives a startup command from the cluster software 1040a and performs the following processing. The fault recovery detection portion 3020 performs processing similar to that of the above-described S12000 through S12070 (see FIG. 11) (S17000 through S17070). After the processing of S17070, the fault recovery detection portion 3020 puts the arbitration disk 211a into a state enabling use, that is, performs resource online processing to logically connect the arbitration disk 211a to a network CN12 or CN13 (S17080). When, in S17040, the fault recovery detection portion 3020 judges the status to be anomaly, the I/O request transmitted in S17020 is released (S17090). Further, when in S17000 the fault recovery detection portion 3020 judges the return value to be other than “GOOD”, processing similar to the above-described S16060 through S16080 (see FIG. 15) is performed (S17100 through S17120). In the above, a number of examples of preferred embodiments of the invention have been explained, but these are illustrations used to explain the invention, and the scope of the invention is not limited to these embodiments and examples. This invention can be implemented with various modifications.
044877374	abstract	A control and power supply circuit is illustrated in the preferred and illustrated embodiment for providing power to a pulsed neutron generator tube. The preferred and illustrated embodiment includes power supplies and control circuits for providing operative power to the pulsed neutron generator tube. The system monitors the voltages supplied to a downhole sonde utilizing a shut regulator circuit which, with the remainder of the control circuitry set forth, properly and in controlled sequence empowers the pulsed neutron generator tube. The tube is provided with power to switch on and such power is switched off in timed sequence to avoid damaging the tube in the event of a malfunction or loss of power from the surface located power source for the sonde.
	claims	1. A moving module of a wafer ion-implanting machine, comprising:a wafer carrier, one end of which is pivotally connected to a wafer tray;a moving shaft, one end of which is fixed to the other end of the wafer carrier so that the moving shaft drives the wafer carrier to move lengthwise;a base, which is fixed to the other end of the moving shaft so that the moving shaft drives the base to move lengthwise;a pair of first magnets, which are fixed to the base;a fixture body, which is located between the pair of first magnets; anda plurality of second magnets, which are fixed onto the fixture body and form a compelling magnetic force between themselves and the first magnets. 2. The moving module of claim 1, wherein the first magnets are permanent magnets. 3. The moving module of claim 1, wherein the first magnets are electrically induced magnets. 4. The moving module of claim 1, wherein the second magnets are permanent magnets. 5. The moving module of claim 1, wherein the second magnets are electrically induced magnets. 6. The moving module of claim 1, wherein the amount of the second magnets on each side of the fixture body is equal. 7. The moving module of claim 1, wherein there is a gap between each of the second magnets and each of the first magnets. 8. The moving module of claim 1, wherein the first magnets and the second magnets are in the shape of rectangle with the same size. 9. A moving module of a wafer ion-implanting machine, comprising:a wafer carrier, one end of which is pivotally connected to a wafer tray;a moving shaft, one end of which is fixed to the other end of the wafer carrier so that the moving shaft drives the wafer carrier to move lengthwise;a base, which is fixed to the other end of the moving shaft so that the moving shaft drives the base to move lengthwise;a pair of magnets, which are fixed to the base; anda fixture body, which is located between the pair of magnets, and is magnetic so that the pair of magnets maintain a compelling magnetic force between opposite sides of the fixture body. 10. The moving module of claim 9, wherein the magnets are permanent magnets. 11. The moving module of claim 9, wherein the magnets are electrically induced magnets. 12. The moving module of claim 9, wherein the fixture body is permanent magnets. 13. The moving module of claim 9, wherein the fixture body is electrically induced magnets. 14. The moving module of claim 9, wherein the amount of second magnets on each side of the fixture body is equal. 15. The moving module of claim 9, wherein there is a gap between the fixture body and the magnets. 16. The moving module of claim 9, wherein at least one of the magnets has a length smaller than the fixture body.
	claims	1. A method for detecting grounding strap breakage in a processing chamber, comprising:monitoring real-time RF related data corresponding to plasma generated in the processing chamber;comparing the real-time RF related data with a pre-determined threshold RF related data;determining the real-time RF related data indicates a worn or damaged state for one or more grounding straps prior to breakage based on comparing the real-time RF related data with the pre-determined threshold RF related data; andgenerating an alert in response to determining the real-time RF related data indicates a worn or damaged state for one or more grounding straps. 2. The method of claim 1, wherein the real-time RF related data includes RF frequency, direct current voltage, voltage peak-to-peak, and/or RF reflected power. 3. The method of claim 1, wherein the pre-determined threshold RF related data is based on RF frequency, direct current voltage, voltage peak-to-peak, or RF reflected power reflecting one or more broken grounding straps in a process recipe matching a current process recipe. 4. The method of claim 1, wherein the comparing the real-time RF related data comprises:using historical RF data for a particular recipe for a desired product to establish the pre-determined threshold RF related data. 5. The method of claim 4, wherein the pre-determined threshold RF related data is based on historical RF data reflecting a certain number of broken grounding straps. 6. The method of claim 4, further comprising:determining the trend in RF data indicative of grounding straps approaching end of service life; andgenerating the alert when grounding straps are nearing the end of service life. 7. The method of claim 1, wherein a controller is coupled to the processing chamber for monitoring real-time RF related data, for comparing the real-time RF related data and for generating the alert, wherein the controller is a database with configurable software modules having sensors for monitoring the real-time RF related data. 8. The method of claim 7, wherein comparing the real-time RF related data with a pre-determined threshold RF related data comprises measuring changes in local impedance on a substrate in the processing chamber. 9. The method of claim 1, wherein monitoring real-time RF related data from plasma generated in the processing chamber further comprises:detecting changes in local plasma impedance with a plurality of plasma property sensors in a processing chamber. 10. The method of claim 1, wherein the real-time RF related data includes voltage peak-to-peak. 11. A non-transitory computer-readable storage medium storing a program, which, when executed by a processor performs an operation for detecting grounding strap breakage in a processing chamber, the operation comprising:monitoring real-time RF related data corresponding to plasma generated in the processing chamber;comparing the real-time RF related data with a pre-determined threshold RF related data;determining the real-time RF related data indicates a worn or damaged state for one or more grounding straps prior to breakage based on comparing the real-time RF related data with the pre-determined threshold RF related data; andgenerating an alert in response to determining the real-time RF related data indicates a worn or damaged state for one or more grounding straps. 12. The non-transitory computer-readable storage medium of claim 11, wherein the real-time RF related data includes RF frequency, direct current voltage, voltage peak-to-peak, and/or RF reflected power. 13. The non-transitory computer-readable storage medium of claim 11, wherein the pre-determined threshold RF related data is based on RF frequency, direct current voltage, voltage peak-to-peak, or RF reflected power reflecting one or more broken grounding straps in a process recipe matching a current process recipe. 14. The non-transitory computer-readable storage medium of claim 11, wherein the comparing the real-time RF related data comprises:using historical RF data to establish the pre-determined threshold RF related data for a particular process recipe for a desired product, wherein historical RF data reflects a certain number of broken grounding straps in the particular process recipe matching a current process recipe. 15. The non-transitory computer-readable storage medium of claim 1, wherein comparing the real-time RF related data with a pre-determined threshold RF related data comprises measuring changes in local impedance on a substrate in the processing chamber. 16. A plasma processing system, comprising:a processor;a plasma processing chamber, comprising:a plurality of chamber walls that at least partially define a processing region;a substrate support disposed within the processing region;a plurality of ground straps that each have a strap body that has a first end and a second end, wherein the first end of each of the plurality of ground straps is coupled to the substrate support and the second end of each of the plurality of ground straps is coupled to at least one of the plurality of chamber walls;an RF power source; andan RF match coupled between the RF power source and a diffuser, wherein the diffuser is adapted to generate a plasma in the process volume when RF energy is delivered to the diffuser from the RF power source, and the RF match further comprises one or more sensors that are configured to provide real-time RF related data to the processor when the RF energy is delivered from the RF power source; anda memory, wherein the memory includes an software routine configured to perform an operation for detecting breakage of one or more of the plurality of ground straps in a processing chamber, the operation comprising:monitoring real-time RF related data corresponding to plasma generated in the processing region of the processing chamber;comparing the real-time RF related data with a pre-determined threshold RF related data;determining the real-time RF related data indicates a worn or damaged state for one or more grounding straps prior to breakage based on comparing the real-time RF related data with the pre-determined threshold RF related data; andgenerating an alert in response to determining the real-time RF related data indicates a worn or damaged state for one or more grounding straps. 17. The plasma processing system of claim 16, wherein the pre-determined threshold RF related data is based on RF frequency, direct current voltage, voltage peak-to-peak, or RF reflected power reflecting one or more broken grounding straps in a process recipe matching a current process recipe. 18. The plasma processing system of claim 16, wherein the comparing the real-time RF related data comprises:using historical RF data for a particular recipe for a desired product to establish the pre-determined threshold RF related data, wherein historical RF data reflects a certain number of broken grounding straps in the particular process recipe matching a current process recipe. 19. The plasma processing system of claim 16, wherein comparing the real-time RF related data with a pre-determined threshold RF related data comprises measuring changes in local impedance on a substrate in the processing chamber. 20. The plasma processing system of claim 16, wherein a controller is coupled to the processing chamber for monitoring real-time RF related data, for comparing the real-time RF related data and for generating the alert, and wherein the controller is a database with configurable software modules having sensors for monitoring the real-time RF related data.
	abstract	An assembly of the type having a water channel extending along a longitudinal axis and having an upper section of larger cross-section area than a lower section and at least one fuel rod receiving groove extending longitudinally on the outer surface of the lower section, fuel rods extending longitudinally and disposed around the water channel and fixing members for fixing at least one fuel rod to the water channel in the at least one groove below the upper section.
	claims	1. A method of improving pattern edge resolution during exposure of a photoresist to a particle beam by using a beam exposure correction for deflector voltages, comprising:determining a correction value using a previous deflector voltage value, a current deflector voltage value, and an exposure time of the current deflector voltage value, wherein the correction value is obtained from look-up tables using the current deflector voltage value as a reference; anddetermining a corrected deflector voltage value by adding the correction value to the current deflector voltage value. 2. The method of claim 1, wherein the determining a correction value includes calculating the current deflector voltage value. 3. The method of claim 1, further including calculating a voltage step value by subtracting the previous deflector voltage value from the current deflector voltage value. 4. The method of claim 1, wherein determining a correction value includes determining a plurality of sub-range correction values. 5. The method of claim 1, further including determining a voltage sub-range of the current voltage deflector value. 6. A method of achieving high writing throughput of a particle beam lithography device, while reducing oscillation or ringing of a deflector voltage, by providing correction for deflector voltages, comprising:determining a voltage step value by subtracting a previous deflector voltage value from a current deflector voltage value;determining a plurality of correction values using the voltage step value and an exposure time for the current deflector voltage value;selecting a current voltage correction value from the plurality of correction values using the current deflector voltage value; anddetermining a corrected deflector voltage value by adding the current voltage correction value to the current deflector voltage value. 7. The method of claim 6, wherein determining a voltage step value includes calculating the voltage step value. 8. The method of either one of claims 6 or 7, wherein determining a plurality of correction values includes providing the voltage step value and the exposure time to at least one look-up table. 9. The method of claim 8, wherein the at least one look-up table is a plurality of look-up tables, and wherein each of the look-up tables outputs one of the plurality of correction values. 10. The method of claim 9, wherein each of the look-up tables is associated with a unique sub-range of a plurality of sub-ranges of potential deflector voltage values. 11. The method of claim 10, wherein selecting a current correction value includes determining the unique subrange of the plurality of sub-ranges of potential deflector voltage values in which the current deflector voltage value is included. 12. The method of claim 11, wherein selecting a current correction value includes selecting the output of the look-up table associated with the unique sub range. 13. The method of claim 6, wherein the determining a corrected deflector voltage value includes calculating the corrected deflected voltage value. 14. A software system which supplies instructions to apparatus used to improve pattern edge resolution during exposure of a photoresist to a particle beam, wherein the software system provides correction for deflector voltages, comprising:at least one module for determining a correction value using a previous deflector voltage value, a current deflector voltage value, and an exposure time for the current deflector voltage value; andat least one module for calculating a corrected deflector voltage value by adding the correction value to the current deflector voltage value. 15. The method of claim 14, wherein the at least one module for determining a correction value includes inputting the previous deflector voltage value, the current deflector voltage value, and the exposure time for the current deflector voltage value into at least one look-up table. 16. The method of claim 14, further including at least one module for calculating a voltage step value by subtracting the previous deflector voltage value from the current deflector voltage value. 17. The method of claim 14, wherein the at least one module for determining a correction value includes determining a plurality of sub-range correction values. 18. The method of claim 14, further including at least one module for determining a voltage sub-range of the current voltage deflector value. 19. A software system which supplies instructions to apparatus used to achieve high writing throughput of a particle beam lithography device, while reducing oscillation or ringing of a deflector voltage, wherein the software system provides correction for deflector voltages, comprising:at least one module for calculating a voltage step value by subtracting a previous deflector voltage value from a current deflector voltage value;at least one module for determining a plurality of correction values using the voltage step value and an exposure time for the current deflector voltage value;at least one module for selecting a current voltage correction value from the plurality of correction values using the current deflector voltage value; andat least one module for calculating a corrected deflector voltage value by adding the current voltage correction value to the current deflector voltage value. 20. The method of claim 19, wherein the at least one module for determining a plurality of correction values includes providing the voltage step value and the exposure time to at least one look-up table. 21. The method of claim 20, wherein the at least one look-up table is a plurality of look-up tables, and wherein each of the look-up tables outputs one of the plurality of correction values. 22. The method of claim 21, wherein each of the look-up tables is associated with a unique sub-range of a plurality of sub-ranges of potential deflector voltage values. 23. The method of claim 22, wherein the at least one module for selecting a current correction value includes determining the unique sub-range of the plurality of sub-ranges of potential deflector voltage values in which the current deflector voltage value is included. 24. The method of claim 23, wherein the at least one module for selecting a current correction value includes selecting the output of the look-up table associated with the unique sub-range.
044217161	summary	DESCRIPTION 1. Technical Field The present invention relates to fault detection apparatus for monitoring a process plant, such as a nuclear power plant, in order to make critical information available to its operator during abnormal events. 2. Background Art One of the lessons to be learned from the incident at the Three-Mile Island Nuclear Station on Mar. 28, 1979, is that nuclear power plants should be designed to provide information to the operator in an easily assimilated form in order to cope with abnormal events which have not been previously analyzed or experienced. In a report on the incident at Three-Mile Island entitled "Staff Report on the General Assessment of Feed Water Transients in PWRs Designed by B&W" dated May 1979 (NUREG-0560), the Nuclear Regulatory Commission stated: "There will always be a residium of possible but not postulated and analyzed situations. To address this, and as an attempt to extend the defense-in-depth concept, we should study ways to make the operator a more effective recovery agent for incident/accident mitigator. Such a study should look for ways to (a) prevent (inhibit) inappropriate actions, and (b) promote productive intervention. An element of the study that could serve both purposes would be an investigation of methods that would furnish the operator with correct, current, digestible information regarding prinicipal plant conditions (i.e., processes, systems, and equipment). The means by which the operator would best use this information should also be considered, however, such means should not be so rigid as to preclude expedited and improvised actions for the operators for unanticipated phenomena." A primary object of the present invention is to provide an apparatus for monitoring critical systems of a nuclear (process) plant and to provide information as to the status thereof, in summary form, to a plant operator. DISCLOSURE OF THE INVENTION Briefly, the above object is accomplished in accordance with the invention by providing an apparatus which monitors a subset of control panel inputs, the subset being those indicators or plant status which are of a critical nature during an unusual event; Displaying primary information as to whether the core is covered and likely to remain covered, including information as to the status of systems needed to cool the core and maintain core integrity; and, providing a secondary display which can be viewed selectively for more detailed information when an abnormal condition occurs, the primary display having means for prompting the operator as to which one of a number of pushbuttons to press to bring up the appropriate secondary display. In accordance with an aspect of the present invention an apparatus is provided which will make information available to the operator in the essential area of reactor core water inventory by keeping a continuous tally of all outflow and inflow to the reactor pressure vessel, and converting these flows of water level relative to the top of the reactor core. In accordance with an aspect of this invention information is provided to the operator as to whether the water level is rising or dropping, and how much time remains before the core will become uncovered if the water level continues to drop at its current rate. In accordance with an aspect of the invention, a means is provided by which the operator can obtain information as to the status of crucial systems upon request. In accordance with an aspect of the invention information is provided in a summary form to the operator, as opposed to providing information as to the status of the entire system. In accordance with an aspect of the invention, means are provided to monitor a number of reactor systems to make available critical information as to water inventory, power level status, and containment status, and to display this critical information in summary form. In accordance with an aspect of the invention, a backup system calculates the reactor vessel water level based upon an analytical model of the reactor vessel and core. The model involves inflows and outflows of water to the reactor vessel, reactor power, reactor pressure, and reactor water mass. In order to improve the model accuracy, the data is reset periodically during normal operation while the monitor is in standby mode so that the calculated water level is consistent with the actual level as indicated by the directly measured process instrumentation level meters.
	summary

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