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039309401	claims	1. A nuclear fuel sub-assembly comprising a shroud of substantially polygonal cross-section containing at least one cluster of elongated parallel fuel pins disposed on a uniform lattice, said shroud having an inlet and an outlet for receiving and discharging a coolant which circulates in the shroud along a direction generally parallel to the pins, each fuel pin being provided over at least the greater part of its length with radially projecting helical spacer means providing a minimum spacing between each fuel pin and the adjacent pins or the shroud, the length of the radial projection of the spacer means on each outer fuel pin of the cluster where said spacer means engage the shroud being smaller than the length of the radial projection of the spacer means on each inner fuel pins of the cluster, the spacer means being a wire, the wires of the inner fuel pins and mounted in tube sections having an external diameter the same as that of the wires carried by the inner fuel pins, said tube sections being placed in the zones in which the outer fuel pins confront inner fuel pins and adjacent outer pins and internal longitudinal ribs on said shroud projecting between the outer fuel pins. 2. A fuel sub-assembly according to claim 1, wherein the cross-section of said longitudinal ribs is such that the flow within each sub-channel limited by outer fuel pins and a flat portion of the shroud is substantially equal to the flow within each sub-channel limited by inner fuel pins only. 3. A fuel sub-assembly according to claim 1, wherein said longitudinal ribs consist of strips secured to the internal face of the shroud. 4. A fuel sub-assembly according to claim 1, wherein said ribs consist of longitudinal deformations of the shroud. 5. A fuel sub-assembly according to claim 1, wherein said ribs are formed on plates which are slidably engaged between the shroud and the fuel cluster.
	claims	1. A collimator assembly comprising:a collimator having a top surface and a bottom surface;a plurality of concentric conical slits formed in the collimator, each conical slit extending from the top surface of the collimator to the bottom surface of the collimator and having a different slit angle oriented such that radiation impinging on the top surface of the collimator is redirected along the conical slit towards a common target isocenter positioned a distance away from the bottom surface of the collimator. 2. The collimator assembly as recited in claim 1, wherein the plurality of concentric conical slits are each spaced apart at the bottom surface of the collimator by a same slit spacing. 3. The collimator assembly as recited in claim 1, wherein some of the plurality of concentric conical slits are spaced apart at the bottom surface of the collimator by different slit spacings than others of the plurality of concentric conical slits. 4. The collimator assembly as recited in claim 1, wherein each of the plurality of concentric conical slits has a same slit width measured at the bottom surface of the collimator. 5. The collimator assembly as recited in claim 4, wherein the slit width for a conical slit is different at the top surface of the collimator than at the bottom surface of the collimator. 6. The collimator assembly as recited in claim 1, wherein some of the plurality of concentric conical slits have different slit widths measured at the bottom surface of the collimator than others of the plurality of concentric conical slits. 7. The collimator assembly as recited in claim 1, further comprising a central bore extending along a central axis of the collimator from the top surface to the bottom surface of the collimator. 8. The collimator assembly as recited in claim 1, further comprising an interaction plate coupled to the top surface of the collimator, the interaction plate being composed of a material that scatters radiation impinging on the interaction plate towards the top surface of the collimator. 9. The collimator assembly as recited in claim 8, wherein the interaction plate includes regions that are positioned and configured to preferentially scatter radiation towards the plurality of concentric conical slits. 10. The collimator assembly as recited in claim 9, wherein the regions in the interaction plate are composed of a different material from the rest of the interaction plate. 11. The collimator assembly as recited in claim 9, wherein the regions in the interaction plate comprise channels formed in the interaction plate, the channels being shaped such that radiation impinging on the channels is preferentially scattered towards the plurality of concentric conical slits. 12. The collimator assembly as recited in claim 8, wherein the interaction plate is composed of at least one of a metal or a metal alloy. 13. The collimator assembly as recited in claim 12, wherein the interaction plate is composed of cerrobend. 14. The collimator assembly as recited in claim 1, wherein the collimator is composed of at least one of a metal or a metal alloy. 15. The collimator assembly as recited in claim 14, wherein the collimator is composed of cerrobend. 16. The collimator assembly as recited in claim 1, wherein the collimator is cylindrical. 17. The collimator assembly as recited in claim 16, wherein the collimator has a circular cross section. 18. The collimator assembly as recited in claim 17, wherein the plurality of concentric conical slits have circular cross sections. 19. The collimator assembly as recited in claim 1, wherein the collimator and the plurality of concentric conical slits are configured to redirect radiation impinging on the top surface of the collimator towards the common target isocenter for radiation energies in a range of 0.5 MeV to 10 MeV.
	summary
040175677	claims	1. In a process for the production of molded block fuel elements having an isotropic structure and useful in gas cooled high temperature power reactors, said fuel elements comprising fuel-containing and fuel-free zones and a graphite matrix in both the fuel-containing and fuel-free zones including the steps of making a fuel-free block-shaped graphite matrix zone by first molding a graphite and binder containing molding composition, making fuel channels and cooling channels in the graphite matrix, encasing coated fuel particles with a binder containing graphite powder and making prepressed fuel rods by molding said encased coated fuel particles, placing said fuel rods into said fuel channels finally, molding the composite body thus formed and carbonizing said composite body the improvement comprising first producing isotropic graphite granulates of density 1.5 to 1.9 g/cm.sup.3 with a porosity of 7.5 to 25 percent by volume and wherein said granulates have an average particle diameter of about 1 mm and each granulate particle contains several hundred thousand isotropically arranged graphite particles by molding in a first molding step from a molding powder having an average grain diameter of about 20 microns and then preliminarily hot molding these isotropic granulates to form said block-shaped fuel-free matrix zone, and afterwards in the final molding step hot molding the composite bodies each consisting of a fuel-free matrix zone with inserted fuel rods at a pressure lower than that applied in said first molding step to form said isotropic fuel elements, the molding powder consisting essentially of a mixture of (A) a binder resin with (B) a member of the group consisting of (1) natural graphite grains, and (2) synthetic graphite grains, and (3) a mixture of both natural and synthetic graphite grains. 2. A process according to claim 1 wherein the granulate is produced at a pressure of about 3 metric tons/cm.sup.2 at room temperature the fuel-free matrix is preliminarily hot molded at a pressure of about 30kg/cm.sup.2 and 70.degree. C., the fuel rods are preliminarily hot molded at a pressure of about 30kg/cm.sup.2 and 70.degree. C. and the composite bodies are finally molded at a pressure of about 60kg/cm.sup.2 and 150.degree. C. 3. A process according to claim 2 wherein the binder resin is a phenol-formaldehyde resin. 4. A process according to claim 1, wherein the resin is a phenol-formaldehyde resin. 5. A process according to claim 1, wherein the granulates are molded at room temperature. 6. A process according to claim 1, wherein particles smaller than the granulate particles of about 1 mm. are again mixed with a molding powder consisting essentially of a mixture of (A) a binder resin with (B) a member of the group consisting of (1) natural graphite, (2) synthetic graphite and (3) both natural and synthetic graphite and used to make new spheres. 7. A process according to claim 1, wherein the isotropic granulates are formed in the shape of spheres at room temperature from the molding powder and then are reduced to granulates of the stated particle size. 8. A process according to claim 1 wherein the isotropic graphite granulates first produced had a density of 1.5 to 1.85 g/cm.sup.3. 9. A process according to claim 1 wherein the isotropic graphite granulates first produced had a density of 1.9 g/cm.sup.3. 10. A process according to claim 1 wherein the degree of condensation of the binder in the fuel-containing zones compared to that in the fuel-free zones is increased so that in the carbonizing of the molded product different shrinking and expansion in both zones is avoided. 11. A process according to claim 10 comprising, providing the block fuel element with cooling channels prior to the heat treatment.
047918012	claims	1. A remotely operable grid tab repair tool for bending an elongated nuclear fuel assembly grid tab, comprising: (a) a frame having an anvil surface; (b) bending means connected to said frame for bending the grid tab against the anvil surface when said bending means is urged against the grid tab; (c) positioning means connected to said frame for positioning said bending means opposite the grid tab; (d) a lever member pivotally connected to said frame and attached to said bending means for urging said bending means against the grid tab when said lever member is pivoted, said bending means capable of exerting a bending moment on the grid tab when said bending means is urged against the grid tab, whereby the grid tab bends when said bending means is urged against the grid tab by the pivoting action of said lever member; and (e) biasing means interposed between said frame and said bending means for biasing said bending means away from the anvil surface. (a) a frame having an anvil surface thereon and having a bore therein; (b) an elongated member having one end slidably extending into the bore; (c) tab bending means connected to another end of said elongated member for bending the grid tab when said tab bending means is biased against the grid tab; (d) positioning means connected to said frame, said positioning means capable of positioning said tab bending means opposite the grid tab; (e) a lever member pivotally connected to said frame and attached to said elongated member for slidably urging said elongated member into the bore, said lever member capable of urging said tab bending means against the grid tab when said lever member is pivoted, said tab bending means capable of exerting a bending moment on the grid tab when said tab bending means is urged against the grid tab, whereby the grid tab bends when said elongated member is urged against the grid tab by the pivoting action of said lever member; and (f) biasing means interposed between said frame and said tab bending means for biasing said tab bending means away from the grid tab. (a) a frame having a bore therein, said frame having an anvil surface thereon and having a first end and a second end; (b) an elongated member having one end slidably extending through the bore; (c) a hook-shaped tab bending member connected to another end of said elongated member for bending the grid tab against the anvil surface; (d) positioning means connected to said frame, said positioning means capable of contacting a fuel assembly for positioning said tab bending member opposite the grid tab; (e) a lever member pivotally connected to said elongated member for slidably urging said elongated member into the bore, said lever member capable of urging said tab bending member against the grid tab when said lever member is pivoted, said tab bending member capable of exerting a bending moment on the grid tab when said tab bending member is urged against the grid tab, whereby the grid tab bends when said elongated member is urged against the grid tab by the urging action of said lever member; and (f) biasing means interposed between said frame and said tab bending means for biasing said tab bending means away from the anvil surface. (a) first coupling means attached to the first end of said frame for connecting said frame to a movable crane, the crane capable of positioning said frame near the fuel assembly; and (b) second coupling means attached to the second end of said frame for connecting said frame to the crane, whereby either the first coupling means or the second coupling means is connected to said frame. (a) a generally L-shaped frame having a first leg having a first end and a second end and having a second leg perpendicular to the first leg, the first leg having a first bore and a second bore therethrough parallel with the second leg, the second leg having a third bore therethrough aligned with the longitudinal axis of the second bore, the second leg having an anvil surface on the terminal end thereof; (b) an elongated member having one end slidably extending through the second bore and the third bore; (c) a hook-shaped, grid tab bending member connected to another end of said elongated member for bending the grid tab against the anvil surface; (d) positioning means connected to said frame, said positioning means capable of matingly abutting an edge of the grid strap for positioning said tab bending member opposite the grid tab; (e) a lever member pivotally connected to said frame and attached to said elongated member for slidably urging said elongated member into the second bore and into the third bore, said lever member capable of urging said tab bending member against the grid tab when a force is applied against said lever member and when said tab bending member is positioned opposite the grid tab, said tab bending member exerting a bending moment on the grid tab when said tab bending member is urged against the grid tab, whereby the grid tab bends when said elongated member is urged against the grid tab by the pivoting action of said lever member; and (f) biasing means interposed between said frame and said tab bending member for biasing said tab bending member away from the anvil surface. (a) first coupling means attached to the first end of said first leg for connecting said frame to a movable crane, the crane capable of positioning said frame near the fuel assembly; and (b) second coupling means attached to the second end of said first leg or connecting said frame to the crane. (a) cable means having one end connected to said lever member for pivoting said lever member toward said frame thereby urging said tab bending member against the grid tab for bending the grid tab; and (b) stop means mounted on said lever member for stopping the pivoting motion of said lever member when the other end of said lever member is pivoted toward said frame. 2. A remotely operable fuel assembly grid tab repair tool for bending a grid tab attached to a grid strap connected to a nuclear fuel assembly grid, comprising: 3. The fuel assembly grid tab repair tool according to claim 2, further comprising a coupling means attached to said frame for connecting said frame to a movable crane, the crane capable of positioning said frame near the fuel assembly. 4. A remotely operable fuel assembly grid tab repair tool for bending a grid tab attached to a grid strap connected to a nuclear fuel assembly grid, comprising: 5. The fuel assembly grid tab repair tool according to claim 4, further comprising: 6. A fuel assembly grid tab repair tool for bending a grid tab attached to a grid strap surrounding a bundle of fuel rods, the grid strap connected to a fuel assembly grid, comprising: 7. The fuel assembly grid tab repair tool according to claim 6 further comprising: 8. The fuel assembly grid tab repair tool according to claim 6 wherein said biasing means is a compressible spring surrounding said elongated member for biasing said tab bending member away from the anvil surface, said spring interposed between said frame and said elongated member. 9. The fuel assembly grid tab repair tool according to claim 6, wherein said positioning means is at least two pins attached to said anvil surface, said pins extending outwardly from the anvil surface and matingly abutting the edge of the grid strap for fine alignment of said tab bending member proximate the grid tab. 10. The fuel assembly grid tab repair tool according to claim 9, wherein said pins are cylinders. 11. The fuel assembly grid tab repair tool according to claim 9, wherein said pins are elongated rectangles having a generally rectangular cross section. 12. The fuel assembly grid tab repair tool according to claim 9, wherein said pins are elongated triangles having a generally triangular cross section. 13. The fuel assembly grid tab repair tool according to claim 6, wherein said tab bending member is 17-4-PH tool stainless steel. 14. The fuel assembly grid tab repair tool according to claim 6, further comprising an alignment blade outwardly extending from the anvil surface, said alignment blade capable of being matingly inserted between two of the fuel rods near the grid tab for fine alignment of said tab bending member proximate the grid tab. 15. The fuel assembly grid tab repair tool according to claim 13, wherein said alignment blade is an elongated rectangle. 16. The fuel assembly grid tab repair tool according to claim 6, wherein the lever member is forked having at least two tines formed at one end thereof, each of the tines pivotally attached each to opposite sides of said second leg, and said lever member having each of the tines thereof attached each to opposite sides of said elongated member. 17. The fuel assembly grid tab repair tool according to claim 16, further comprising:
043371183	abstract	A nuclear reactor power monitoring system for monitoring the power level of a reactor and preventing an excessive rise thereof attributable to a transient increase in the core coolant flow rate before the reactor is scrammed. The system include an operating region monitor (ORM) for blocking the increase in the core coolant flow rate or running-back the flow rate when the power level exceeds a predetermined coolant block threshold power level which is a function of the core coolant flow rate.
	description	This is a continuation of PCT/JP06/302761 filed Feb. 16, 2006 and published in Japaneses. 1. Technical Field The present invention relates generally to an X-ray shielding device and, more particularly to an X-ray shielding device for preventing a patient from being exposed to a portion of X-ray radiation in an X-ray fluoroscopic apparatus. 2. Background Art In medical applications, diagnosis based on an X-ray fluoroscopic apparatus has been traditionally carried out. More recently, the X-ray fluoroscopic apparatus has been also used for treatment procedures in addition diagnosis procedures. It has been common to treat a patient, for example, suffering from cranial aneurysm by open brain surgery under general anesthesia, but, recently, not a few intravascular surgeries may be conducted. The intravascular surgery may be conducted based on a microcatheter which is delivered through a blood vessel, which may involve use of an X-ray fluoroscopic apparatus (an angiographic system). Such an intravascular surgery may conveniently require no large incisions in the human body and be less invasive. When the X-ray fluoroscopic apparatus is adapted to be used for treatment, however, it can be forced to irradiate the human body with X-ray radiation for relatively longer irradiation time, as compared to diagnosis. Also, X-rays may be emitted to not only a site of the human body requiring the fluoroscopy, but also an adjacent site of the human body requiring no fluoroscopy. It will be understood that such an undesirable medical exposure of the patient, in particular certain sites of the human body should be reduced or even eliminated as far as possible. Such reduction in the X-ray exposure is very important for some human body site less resistive to radiation, i.e. requiring less exposure dose. For example, in the case of intravascular surgery on the human cranial region or head, the reduction in the exposure of human eyeballs, in particular lenses thereof is absolutely important from the standpoint of prevention of cataract. Japanese Laid-Open Patent Application No. 2004-49849 discloses an X-ray shielding device used in conjunction with an X-ray fluoroscopic apparatus and intended to reduce the undesirable medical X-ray radiation exposure as mentioned above. The disclosed X-ray shielding device includes a radiation shielding disk made of lead disposed the head of the patient and an X-ray tube of the X-ray fluoroscopic apparatus situated below the patient head. The shielding disk can be translated in an X-Y plane and also tilted at a desired angle about an X axis, which shielding disk may be in turn adapted to be rotated about a Z axis. While the X-ray tube radiates X-rays in the Z axis direction, the X-rays is caused to be continuously shielded by a circular area defined the shielding disk being rotated. Such conventional X-ray shielding device may require a complex operating mechanism which allows the pivotal and continuous rotating movements of the shielding disk about the X and Z axes, respectively in addition to the translational movement in the X-Y plane thereof. Typically, the X-ray shielding lead disk may be situated in an upright position or in the Z axis direction. This is not feasible in terms of design considerations because of a limited space between the head of the patient and the X-ray tube of the X-ray fluoroscopic apparatus. In addition, displacement of an X-ray source of the X-ray fluoroscopic apparatus may require a temporal interruption of the operation and then a manual repositioning of the shielding disk in place. It is an object of the present invention to solve the problems as described above, and to provide an X-ray shielding device for use with an X-ray fluoroscopic apparatus that is adapted to provide a better space-saving configuration and make effective use of a limited space available in a medical environment and also that can be arranged in such a manner to automatically move an X-ray shielding disk in synchronization with movement of the X-ray source to shield a particular site or area of a subject from the X-ray radiation. In order to the above object, the present invention provides an X-ray shield device for use with an X-ray fluoroscopic apparatus for fluoroscopically visualizing a certain site of a subject, comprising an X-ray generator containing an X-ray source, an X-ray detector associated with the X-ray generator and including a projection plane disposed opposed to the X-ray source, and a support member disposed between the X-ray source and the projection plane independently of the X-ray detector for supporting the subject, the X-ray shield device being adapted to prevent a specified site of the subject from exposure to the X-ray from the X-ray source, said X-ray shield device comprising at least one X-ray shielding plate positioned between the X-ray source and the support member; a shielding plate driving mechanism including a supporting portion for supporting said X-ray shielding plate, said shielding plate driving mechanism being operable to move the shield plate supported by the supporting portion in a direction transverse to a path of X-ray irradiation; and a control unit for controlling operation of said shielding plate driving mechanism to cause it to move said shielding plate in a manner so as to shield said specified site of the subject from the X-ray from the X-ray source of the X-ray generator upon movement of the X-ray generator and the X-ray detector relative to the support member. In the X-ray shield device according to the present invention, preferably, said supporting portion of the shielding plate driving mechanism is operable to support selected one of said X-ray shielding plates of different sizes for exchange. In accordance with one aspect of the present invention, preferably, said control unit is operable to move said X-ray shielding plate to a shielding position on which said X-ray shielding plate is to be centered and at which a line extending centrally through the X-ray source and the specified site of the subject to be shielded from the X-ray irradiation from the X-ray source, intersects a plane in which said shielding plate is moved. In accordance with another aspect of the present invention, preferably, the X-ray shield device also comprises a shielding position determining means for determining said shielding position, said control unit being operable to move said X-ray shielding plate to said shielding position determined by said shielding position determining means. In accordance with another aspect of the present invention, preferably, said shielding position determining means comprises; a position of X-ray source measuring device for measuring the position of the X-ray source S relative to a common reference point; a position of shielding plate driving mechanism measuring device for measuring the position of the shielding plate driving mechanism relative to said common reference point; a position of non-irradiation site measuring device for measuring the position of said specified site relative to said common reference point; and a computing unit for computing said shielding position based on data from said X-ray source position measuring device, data from said shielding plate driving mechanism position measuring device and data from said non-irradiation position measuring device. In accordance with still another aspect of the present invention, preferably, said control unit is operable to move said X-ray shielding plate to a shielding position on which said X-ray shielding plate is to be centered and at which a line extending centrally through the X-ray source and a position of an image of the specified site of the subject on a projection plane where the specified site of the subject is projected, intersects a plane in which said shielding plate is moved. In accordance with still another aspect of the present invention, preferably, the X-ray shield device further comprises a shielding position determining means for determining said shielding position, said control unit being operable to move said X-ray shielding plate to said shielding position determined by said shielding position determining means. In accordance with another aspect of the present invention, preferably, said shielding position determining means comprises; a position of X-ray source measuring device for measuring the position of the X-ray source relative to a common reference point; a position of shielding plate driving mechanism measuring device for measuring the position of the shielding plate driving mechanism relative to said common reference point; a position of non-irradiation site projection image measuring device for measuring the position of the image of said specified site of the subject that is projected on the projection plane relative to said common reference point; and a computing unit for computing said shielding position based on data from said X-ray source position measuring device, data from said shielding plate driving mechanism position measuring device and data from said non-irradiation site's projection image position measuring device. In accordance with still another aspect of the present invention, preferably, the X-ray shield device further comprises a shielding plate size determining means for determining a size of said X-ray shielding plate to be placed at said shielding position that is suitable for said specified site of the subject to be shielded from the X-ray irradiation from the X-ray source. In accordance with another aspect of the present invention, preferably, said shielding plate size determining means comprises; said shielding position determining means, a size of non-irradiation site storing device for storing data relating to the size of a non-irradiation site of the subject projected onto a plane perpendicular to the center line which passes through the X-ray source and the center of the non-irradiation site, and a computing unit for computing the size of the X-ray shielding plate suitable for the non-irradiation site of the subject based on data provided from said shielding position determining means and data provided from said non-irradiation site's size storing device. In accordance with still further aspect of the present invention, preferably, the X-ray shield device further comprises an X-ray shielding plate exchanging means for exchanging said X-ray shielding plate supported by said supporting portion of the X-ray shielding plate driving mechanism for another X-ray shielding plate of different size. In accordance with another aspect of the present invention, preferably, said shielding plate exchanging means comprises a shielding plate rack for releasably holding more than one X-ray shielding plates of different sizes; said supporting portion of the X-ray shielding plate driving mechanism is configured to releasably support said X-ray shielding plate; and said X-ray shielding plate driving mechanism is constructed to move the supporting portion thereof in such a manner that the supporting portion is caused to pass the X-ray shielding plate supported thereby onto said shielding plate rack which can hold that X-ray shielding plate and to receive thereon selected one of X-ray shielding plates held by the shielding plate rack. In accordance with still another aspect of the present invention, preferably, said control unit is operable to control said X-ray shielding plate exchanging means in such a manner that said supporting portion of the X-ray shielding plate driving mechanism is caused to pass the X-ray shielding plate supported thereby onto said shielding plate rack which can hold that X-ray shielding plate and to receive thereon an X-ray shielding plate of X-ray shielding plates held by the shielding plate rack whose size is determined by said shielding plate size determining means. In accordance with another aspect of the present invention, preferably, said shielding plate driving mechanism is adapted to move the X-ray shielding plate along said path of X-ray irradiation. In accordance with still another aspect of the present invention, preferably, the X-ray shield device further comprises a command input unit operatively connected to said control unit. In accordance with another aspect of the present invention, preferably, said X-ray shield device comprising at least two X-ray shielding plates positioned between the X-ray source and the support member in order to prevent a plurality of specified sites of the subject from exposing to the X-ray from the X-ray source, and at least two shielding plate driving mechanism each operable to move the respective X-ray shielding plate, each of said shielding plate driving mechanisms being adapted to move the respective X-ray shielding plate in a direction transverse to a respective path of X-ray irradiation at a different position on said X-ray irradiation path. As can be appreciated by those skilled in the art, the present invention provides an X-ray shield device having a better space-saving configuration and capable of being arranged in such a manner to automatically move an X-ray shield plate in synchronization with movement of the X-ray source to shield a particular site or area of a subject from the X-ray radiation. Several embodiments of the present invention will now be described with reference to the accompanying drawings. These embodiments will be discussed in connection with an X-ray fluoroscopic apparatus which may be used with an angiographic system. Referring to FIGS. 1 and 2, there is schematically shown a known angiographic system generally designated by a reference numeral 1. This angiographic system 1 has a C-shaped fixed arm 2 which is provided at its bottom end with an X-ray generator 3 which contains an X-ray source S. An X-ray detector 4 is mounted on the top of the arm 2. The X-ray detector 4 comprises a projection plane P disposed opposed to the X-ray source S. As shown in FIG. 3, an upper support surface (ceiling) located above the fixed arm 2 includes arm rails 5 mounted thereon. A slider 6 is slidably mounted and driven on the arm rails 5 by a motor 6A. Below the slider 6 is disposed a reverse L-shaped support arm 7. The support arm 7 includes a horizontal portion 7A which is mounted on the underside of the slider 6 so that the support arm 7 can be rotated about a vertical axis in direction θ1 by a motor 7C. The support arm 7 also includes a vertical portion 7B on the inner side of which a connector member 8 is mounted so that it can be rotated about a horizontal axis in direction θ2 by a motor 8A. The C-shaped fixed arm 2 movably extends through the connecting member 8 in the vertical direction along direction θ3 and can be driven by a motor 8B through the connecting member 8. The X-ray detector 4 can be moved away from and toward the X-ray generator 3 by a motor 4A. As shown in FIGS. 1 and 2, the angiographic system 1 also has a bed 9 or support which is disposed between the X-ray source S and a projection plane P. A subject, e.g., a patient PA or a mimic object (phantom) is to be placed on the bed 9. The bed 9 may be of a structure that can be moved in the vertical and/or horizontal directions by a known drive mechanism, for example, by a combination of motor and gear train. Furthermore, the bed 9 may be operated independently of the X-ray detector. The angiographic system 1 further has an image display means, for example, a monitor (not shown) for displaying the image of the patient PA projected onto the projection plane P. The angiographic system 1 further has an X-ray shield device. X-ray shielding disk 20: The X-ray shield device includes X-ray shielding disks or plates 20 to be positioned between the X-ray source S of angiographic system 1 and the bed 9. Each of the X-ray shielding disks 20 is made of an X-ray shieldable material, such as lead or tungsten. The shielding disks 20 are circular in this embodiment, but they may take any suitable shape. Alternatively, each of the X-ray shielding disks 20 may be formed by laminating a plate-shaped member made of a material harder than the aforementioned X-ray shieldable material (e.g., lead) on a plate-shaped member made of said X-ray shieldable material. Shielding disk drive mechanism 30: The X-ray shield device also includes a shielding disk driving mechanism 30 for moving the shielding disks 20 in a plane parallel to the projection plane P, namely, a plane SMP (a plane in which the shielding disk is moved) perpendicular to a path of X-ray irradiation which extends from the X-ray source S to the projection plane P. FIGS. 1-4 show the shielding disk drive mechanism 30 which is secured to the fixed arm 2 in a manner to provide a fixed distance between the shielding disk drive mechanism 30 and the X-ray generator 3. However, the shielding disk drive mechanism 30 is not particularly limited to such an arrangement. For example, the shielding disk drive mechanism 30 may be arranged so that it can be supported by any support means independent of the fixed arm 2 and moved between the bed 9 and the X-ray source S in said path of X-ray irradiation. Alternatively, the shielding disk drive mechanism 30 may be stationary if both the X-ray generator 3 and X-ray detector 4 opposed to the X-ray generator 3 are stationary. In such a case, the shielding disk drive mechanism 30 may be fixedly mounted on the underside of the bed, for example. In any case, when the X-ray shield device of the present invention is to be used, the shielding disk drive mechanism 30 should be positioned such that the shielding disk movement plane SMP will be parallel to the projection plane P of the X-ray detector 4. As shown in FIG. 5A, the shielding disk drive mechanism 30 has a flat base frame 31 on which a pair of X-axis guides 32A and 32B are fixedly mounted to extend parallel to each other. A first sliding member 33 is slidably mounted on one of the X-axis guides 32A. The first sliding member 33 is driven by a first stepping motor 33A through a linear ball-and-screw shaft (not shown). A Y-axis guide 34 extends from the first sliding member 33 perpendicular to the X-axis guides 32A and 32B. The Y-axis guide 34 includes a free end portion which is slidably supported by the X-axis guide 32B through a guide roller (not shown) which is mounted on the underside of the Y-axis guide 34. A second sliding member 35 is slidably mounted on the Y-axis guide 34. The second sliding member 35 is driven by a second stepping motor 35A mounted on the Y-axis guide 34 through a linear ball-and-screw shaft. The motors 33A and 35A may be servomotors and preferably provided with brakes. A mechanism for driving each of the sliding members 33 and 35 may be any known mechanism such as a combination of a motor with a rack and pinion mechanism or a timing belt mechanism. A radioparent or X-ray transmission arm 36 extends from the second sliding member 35 parallel to the base frame 31. The arm 36 includes a supporting portion for supporting the X-ray shielding disk 20. The supporting portion of the arm 36 may be of any shape and structure if it can support the X-ray shielding disk 20. As can be seen from FIG. 5B, the supporting portion of the arm 36 in this embodiment is formed into a dish-shaped tray 36A including an upwardly extending periphery so that the dish-shaped tray 36A can detachably support X-ray shielding disks 20 having different sizes. The central portion of the tray 36A includes a guide/retention aperture 36a formed therethrough. On the other hand, a protruding pin 20a extends downwardly from the underside of the X-ray shielding disk 20 at the central part thereof. The protruding pin 20a can be inserted into and held by the guide/retention aperture 36a in the supporting portion of the arm 36. Thus, the X-ray shielding disk 20 can be detachably supported by the supporting portion of the arm 36. The X-ray shielding disk 20 also includes a protruding pin 20b extending upwardly from the top of the X-ray shielding disk 20 at the central part thereof. Each of the first and second stepping motors 33A and 35A includes an encoder which can output the information about the position of the corresponding one of the first and second sliding members 33, 35. Therefore, the position of the X-ray shielding disk 20 in the shielding disk drive mechanism 30 can be always specified. The base frame 31 further includes a through-hole 37 through which X-rays are allowed to pass through. The aforementioned structure of the shielding disk drive mechanism 30 for moving the X-ray shielding disks 20 in the shielding disk movement plane SMP is per se realized by any one of various known techniques, but not limited to such a structure as described in connection with FIG. 5. For example, the shielding disk drive mechanism 1 may be configured as shown in FIG. 17. This alternative shielding disk drive mechanism generally denoted by a reference numeral 200 includes a base frame 231 having a through-hole 237 through which X-rays pass. The base frame 231 includes an X-axis guide 232A anchored thereto. The X-axis guide 232A rotatably supports a pair of rollers 240A and 240B spaced apart from each other along the length thereof. One of the rollers 240A is driven by a motor 240a. An endless drive belt 241 is passed around and spanned between the rollers 240A and 240B. The endless drive belt 241 is partially fastened to the respective rollers 240A and 240B. A Y-axis guide 234 is slidably guided in a guide slot 232a of the X-axis guide 232A along the length thereof and extends perpendicular to the X-axis guide 232A. The Y-axis guide 234 is fastened at one end to the endless drive belt 241. Therefore, when the endless drive belt 241 is driven, the Y-axis guide 234 is slidably driven along the length of the X-axis guide 232A. The Y-axis guide 232A rotatably supports a pair of rollers 250A and 250B spaced apart from each other along the length thereof. One of the rollers 250A is driven by a motor 250a. An endless drive belt 251 is passed around and spanned between the rollers 250A and 250B. The endless drive belt 241 is partially fastened to the respective rollers 240A and 240B. The Y-axis guide 234 also has a slide guide 234A which extends therefrom in the longitudinal direction. A shielding disk support member 260 is slidably mounted on the slide guide 234A. The shielding disk support member 260 is anchored to the endless drive belt 251. Therefore, when the endless drive belt 251 is driven, the shielding disk support member 260 is slidably driven along the slide guide 234A. Any one of various X-ray shielding disks 220 having different sizes can be detachably mounted on the shielding disk support member 260 through screws. The endless drive belt 251, slide guide 234A and shielding disk support member 260 are formed of any material of low X-ray shielding property such as plastic. In this manner, such a shielding disk drive mechanism 200 can also move each of the X-ray shielding disks 20 (220) in the aforementioned shielding disk movement plane SMP. Control Unit 100: As shown in FIG. 6, the X-ray shield device further includes a control unit 100 for controlling the shielding disk drive mechanism 30. That is to say, various stepping motors used for the shielding disk drive mechanism 30 are controlled by the control unit 100 (in both the embodiments). The control unit 100 is connected to a command input unit 110 such that all or part of the control executed by the control unit 100 can be manually performed through the command input unit 110. Means for exchanging one X-ray shielding disk for another: The X-ray shield device further includes a shielding disk exchanging means for exchanging one X-ray shielding disk 20 supported by the supporting portion of the arm 36 for another X-ray shielding disk 20 of different size. The shielding disk exchanging means has a shielding disk rack 40 mounted on the base frame 31, as shown in FIG. 5A. As shown in FIG. 5B, the shielding disk rack 40 comprises a plurality of electromagnet members 40X which, in this embodiment, releasably holds six X-ray shielding disks 20 having different diameters. Each of the electromagnet members 40X can hold the corresponding one of the X-ray shielding disks 20 when that electromagnet member 40X is energized. When the electromagnet member 40X is de-energized, it can release that X-ray shielding disk 20. Each of the electromagnet members 40X includes a guide/retention aperture 40x formed in the underside thereof. The guide/retention aperture 40x is adapted to guide and retain the protruding pin 20b of the corresponding X-ray shielding disk 20. Each of the electromagnet members 40X in the shielding disk rack 40 is energized or de-energized according to a command from the control unit 100. Therefore, when the tray 36A (which does not hold any shielding disk 20 now) of the arm 36 in the shielding disk drive mechanism 30 has been moved below one of the electromagnet members 40X holding an X-ray shielding disk 20 of the desired size and if that electromagnet member 40X is de-energized, the shielding disk 20 is released from the electromagnet member 40X and then received by the tray 36A. Thus, the protruding pin 20a of that shielding disk 20 is guided and held by the guide/retention aperture 36a of the tray 36A. On the other hand, when the tray 36A of the arm 36 holding a shielding disk 20 has been moved below the empty electromagnet member 40X and if the latter is energized, the shielding disk 20 of the tray 36A is electromagnetically attracted by that electromagnet member 40X. The protruding pin 20b of that shielding disk 20 is then guided and held by the guide/retention aperture 40x of the electromagnet member 40X. The mechanism for holding and releasing the X-ray shielding disks 20 in the shielding disk rack 40 is not limited to the aforementioned arrangement, but may be realized by any suitable known technique. Alternative form of shielding disk drive mechanism 30 plus shielding disk exchanging means: FIG. 7 shows an alternative form of such shielding disk drive mechanism 30 plus shielding disk exchanging means as shown in the FIG. 5. Only parts of this alternative form different from those of the shielding disk drive mechanism 30 plus shielding disk exchanging means shown in the FIG. 5 will now be described. Components similar to those of the shielding disk drive mechanism 30 plus shielding disk exchanging means shown in the FIG. 5 will be denoted by similar reference numerals. Referring to FIG. 7, there is shown a shielding disk drive mechanism 30A which includes a first spindle 201 rotatably mounted on a base frame 31 and a first arm 202 mounted on the first spindle 201. The first spindle 201 can be moved upwardly and downwardly in a direction perpendicular to the base frame 31. In a further alternative form, the first arm 202 may be moved (up and down) along the first spindle 201. Alternatively, a third spindle 205 which will be described later may be moved vertically relative to the base frame 31. Alternatively, a first support housing 206 which will be described later may be moved (up and down) along the third spindle 205. In brief, it is preferred that arms 206A and 208A which will be described later can be moved up and down relative to the base frame 31. Referring again to FIG. 7, there is shown a second spindle 203 which is rotatably mounted on the free end portion of the first arm 202 and which extends parallel to the first spindle 201. A second arm 204 is mounted on the second spindle 203. A third spindle 205 is rotatably mounted on the free end portion of the second arm 202 and extends parallel to the first spindle 201. A first support housing 206 is rotatably mounted on the third spindle 205. A radioparent arm 206A extends from the first support housing 206 parallel to the base frame 31. The free end portion of this arm 206A includes a first supporting portion for supporting the X-ray shielding disk 20. The first support housing 206 also includes a guide bore (not shown) formed therein and which extends in a direction perpendicular to the arm 206A and parallel to the base frame 31. A linearly slidable arm 207 is slidably disposed within this guide bore. The linearly slidable arm 207 is driven by a stepping motor (not shown) which is received in the first support housing 206. A second support housing 208 is mounted on the linearly slidable arm 207 at one end. A radioparent arm 208A extends from the second support housing 208 parallel to the arm 206A. The free end portion of the arm 208A includes a second supporting portion for supporting the X-ray shielding disk 20. In this regard, the first spindle 201, second spindle 203 and third spindle 205 can be rotatably driven by stepping motors (not shown) or similar means. The first spindle 201 is further moved up and down by a combination of a stepping motor (not shown) with a linear ball-and-screw shaft mechanism. Each of these stepping motors comprise an encoder which can output the information about the position (angular position) of the corresponding one of the spindles 201, 203 and 205 and also output the information about the vertical position of the first spindle 201 relative to the base frame 31. In this regard, each of the aforementioned drive motors may be in the form of servomotor and is preferably provided with a brake. In addition, the position information of said slidable arm 207 can also be provided from a stepping motor (not shown) which is housed within the first support housing 206. Therefore, the shielding disk drive mechanism 30 according to this alternative embodiment can always determine the position of the X-ray shielding disk 20 supported by each of the arms 206A and 208A. The two arms 206A and 208A is to protect both the eyes of a patient. The distance between the two X-ray shielding disks can be regulated by the slidable arm 207 depending on the distance between the eyeballs. On the other hand, if only a single X-ray shielding disk 20 is used as in the shielding disk drive mechanism 30 shown in FIG. 5A, the X-ray emitted from the X-ray source S may be restricted into a reduced area of radiation so that an eyeball not shielded by the X-ray shielding disk 20 will not be irradiated by X-rays. According to this alternative embodiment, the shielding disk exchanging means also has a shielding disk rack 40A mounted on the base frame 31. As seen best from FIGS. 7-9, the shielding disk rack 40A releasably holds two sets of X-ray shielding disks 20 (three in each set according to this embodiment) having different sizes. The shielding disk rack 40A comprises holding bars 40a for releasably holding several X-ray shielding disks 20. Each of the holding bars 40a includes three holding recesses 41 formed therein and extending perpendicular to the base frame 31. According to this alternative embodiment, each of the X-ray shielding disks 20 comprises a first reduced diameter portion 21 extending downwardly from the underside thereof at the center and a second reduced diameter portion 22 extending downwardly from the bottom end of the first reduced diameter portion 21 at the center, the second reduced diameter portion 22 having its diameter smaller than that of the first reduced diameter portion 21. The diameter of the second reduced diameter portion 22 is slightly smaller than that of the holding recess 41 in the shielding disk rack 40A while the diameter of the first reduced diameter portion 21 is larger than that of the holding recess 41 in the shielding disk rack 40A. The first reduced diameter portion 21 is formed of magnetic material. Thus, the first reduced diameter portion 21 is magnetically attracted by the corresponding holding bar 40a when the second reduced diameter portion 22 is inserted into the corresponding holding recess 41 of the holding bar 40a so that the bottom face of the first reduced diameter portion 21 is engaged by the holding bar 40a. Thus, when the fixed arm 2 is rotated from such a position as shown in FIGS. 1-3 so that the shielding disk drive mechanism 30 and thus the shielding disk rack 40A is inverted, the X-ray shielding disk 20 can be prevented from falling out of the shielding disk rack 40A. The second reduced diameter portion 22 may be formed of magnetic material rather than the first reduced diameter portion 21. As can be seen best from FIG. 8, the free end (i.e., the first or second supporting portion) of each of the arms 206A and 208A in the shielding disk drive mechanism 30A includes a U-shaped or semi-oval cutout portion 210 and a magnet 211 located adjacent to the cutout portion 210. The width of the U-shaped cutout portion 210 is slightly larger than the first reduced diameter portion 21 of the X-ray shielding disk 20. In conjunction with the magnet 211, the underside of each of the X-ray shielding disks 20 to be used is formed of any suitable material that can be magnetically attracted by the magnet 211. If both the arms 206A and 208A of the shielding disk drive mechanism 30A hold no X-ray shielding disk 20, each of the arms 206A and 208A can receive an X-ray shielding disk 20 of the desired size from the corresponding holding bar 40a by first regulating the spacing between the two arms 206A and 208A into the spacing between the corresponding set of X-ray shielding disks 20 in the shielding disk rack 40A, thereafter moving the free ends of the arms 206A and 208A to approach the respective X-ray shielding disks 20 held by the shielding disk rack 40A as shown in FIG. 9(A), and finally positioning the first reduced diameter portions 21 of the X-ray shielding disks 20 in the respective U-shaped cutout portions 210 as shown in FIG. 9(B). Then, the first spindle 201 is moved upwardly from the standard plane in the base frame 31 so that the arms 206A and 208A are caused to be engaged by the undersides of the corresponding X-ray shielding disks 20 as shown in FIG. 9(C). Thus, the magnets 211 of the arms 206A and 208A magnetically attract the undersides of the X-ray shielding disks 20 into engagement therewith. Subsequently, the first spindle 201 is further moved upwardly from the base frame 31 against the magnetic force acting between the holding bars 40a and the first reduced diameter portions 21. Thus, the second reduced diameter portions 22 of the X-ray shielding disks 20 are pulled out from the holding recesses 41 of the shielding disk rack 40A as shown in FIG. 9(D). The arms 206A and 208A that have received the X-ray shielding disks 20 are then moved away from the shielding disk rack 40A. Thereafter, the first spindle 201 is moved downwardly to the standard plane so that the X-ray shielding disks 20 are positioned in a shielding disk movement plane SMP as will be described. In order to cause the X-ray shielding disks 20 on the arms 206A and 208A to be held by the shielding disk rack 40A, the aforementioned operation may be reversed. FIGS. 9-1 to 9-3 show an alternative embodiment of the shielding disk exchanging means shown in FIGS. 8 and 9. According to this alternative embodiment, the free end portion of each of the arms 206A and 208A in the shielding disk drive mechanism 30A includes a guide/hold aperture 212 formed therethrough, in place of the cutout portions 210 shown in FIGS. 8 and 9. On the other hand, each of the X-ray shielding disks 20 to be used includes a protruding pin 21a extending downwardly from the underside thereof at the center. The protruding pin 21a is so dimensioned and shaped so that it can be guided and held by the corresponding one of guide/hold apertures 212. Each of the X-ray shielding disks 20 also includes a protruding pin 21b extending upwardly from the top thereof at the center. The protruding pin 21b includes a circumferential groove 21c formed therein. According to this alternative embodiment, the shielding disk rack 40A of FIGS. 8 and 9 is replaced by a shielding disk rack 40B. The shielding disk rack 40B comprises a horizontal fixed plate 42, a protruding wall 43 extending upwardly from one end of the horizontal fixed plate 42 and a pivot plate 44 pivotably mounted in a bifurcated portion (not shown) which is cut out at the other end of the horizontal fixed plate 42. A spring 45 is operatively mounted between the protruding wall 43 and the top end of the pivot plate 44. The spring 45 acts such that the pivot plate 44 is rotated counter-clockwise as viewed in FIG. 9-1. A shielding disk moving/holding member 46 is mounted on the lower part of the pivot plate 44 which is located below the horizontal fixed plate 42. The shielding disk moving/holding member 46 extends downwardly from the pivot plate 44, the bottom free end portion 46a thereof being bent to extend into the circumferential groove 21 of the protruding pin 21b in the X-ray shielding disk 20. A shielding disk fixing/holding member 47 is located opposed to the shielding disk moving/holding member 46. A shielding disk 20 is held in the shielding disk rack 40B when the bottom free end 46a of the shielding disk moving/holding member 46 extending into the circumferential groove 21c of the protruding pin 21b of the shielding disk 20 presses the protruding pin 21b against the shielding disk fixing/holding member 47. The shielding disk fixing/holding member 47 includes a threaded hole 47B formed therein. A screw stopper 48 threadedly engages in the threaded hole 47B. The screw stopper 48 functions to prevent the pivot plate 44 from being rotated beyond a predetermined position. An electromagnet 49 is located below the horizontal fixed plate 42 and adjacent to the lower part of the pivot plate 44. When this electromagnet 49 is energized, it can magnetically attract the lower part of the pivot plate 44 into engagement therewith against the biasing force of the spring 45. According to this alternative embodiment, each of the arms 206A and 208A receives an X-ray shielding disk 20 of the desired size from the shielding disk rack 40B by moving the free ends of the arm 206A or 208A by the shielding disk drive mechanism 30A so that the guide/hold aperture 212 thereof is positioned below the lower part of the corresponding protruding pins 21a in that X-ray shielding disk 20 held by the shielding disk rack 40B, as shown in FIG. 9-1. Subsequently, the electromagnet 49 is energized. Then, the corresponding pivot plate 44 is rotated clockwise against the biasing force of the spring 45, as shown in FIG. 9-2. As a result, the free and bottom end 46a of the corresponding shielding disk moving/holding member 46 is separated from the circumferential groove 21c of the protruding pin 21b in the X-ray shielding disk 20. Then, the X-ray shielding disk 20 falls freely. The protruding pin 21a of the X-ray shielding disk 20 is guided and held by the guide/hold aperture 212 of each of the arms 206A and 208A while at the same time the X-ray shielding disk 20 is magnetically attracted by each of the arms 206A and 208A. When the first spindle 201 is subsequently moved downwardly from the standard plane, each of the arms 206A and 208A is moved downwardly away from the shielding disk rack 40B, as shown in FIG. 9-3. Thereafter, the first spindle 201 is moved upwardly to the standard plane so that the X-ray shielding disk 20 is located in a shielding disk movement plane SMP described below. Before or after this time, the electromagnet 49 is de-energized. Thus, the free and bottom end portion 46a of the corresponding shielding disk moving/holding member 46 is returned back to the same position as is shown in FIG. 9-1. In order to cause the shielding disk rack 40B to hold the X-ray shielding disks 20 held by the arms 206A and 208A, the aforementioned operation may be reversed. Shielding position determining means: The X-ray shield device also has a shielding position determining means for computing or determining a “shielding position SH” which is a position at which each shielding disk 20 should be centered and at which a line C extending through the X-ray source S and the center of a particular location on a patient PA at which the irradiation of the X-ray from the X-ray source S should be blocked, intersects a plane in which the shielding disk is moved by means of the shielding disk drive mechanism 30. For convenience sake, the following description will be made assuming that a particular location on the patient PA at which the irradiation of the X-ray from the X-ray source S should be blocked is an eyeball EB. The shielding position determining means comprises an X-ray source position measuring device for measuring the position of the X-ray source S relative to a common reference point CSP shown in FIG. 10, a shielding disk driver position measuring device for measuring the position of the shielding disk drive mechanism 30 relative to the common reference point CSP, an eyeball position measuring device for measuring the position of an eyeball EB relative to the common reference point CSP, and a computing unit 60 for computing or determining the shielding position SH based on data from the X-ray source position measuring device, data from the shielding disk drive mechanism position measuring device and data from the eyeball position measuring device. The term “common reference point CSP” used herein may refer to any suitable point (position) such as a point on a floor on which the angiographic system 1 and X-ray shield device are placed. In this regard, arrows A, B and C in FIG. 10 indicate position vectors determined based on the common reference point CSP. X-ray source position measuring device: The X-ray source position measuring device may be configured by such means as exemplified below: (1) Position output means of the angiographic system 1: If each of the aforementioned motors 6A, 7C, 8A and 8B in the angiographic system 1 is provided with a position output means such as an encoder which can output the positional data of the corresponding movable part moved by the corresponding one of these motors in the angiographic system 1, the X-ray source position measuring device can be configured by such position output means and a computing unit 60 for computing or determining the position of the X-ray source S relative to the common reference point CSP based on position output data from that position output means. (2) Position measuring device to be retrofitted: If each of the motors 6A, 7C, 8A and 8B of the angiographic system 1 is not provided with position output means such as an encoder which can output the position data of the corresponding movable part moved by that motor in the angiographic system 1, the X-ray source position measuring device may be configured by a retrofit position measuring device for measuring the position of the movable part in the angiographic system 1 such as a linear encoder or inclination sensor retrofitted to that movable part and a computing unit 60 for computing or determining the position of the X-ray source S relative to the common reference point based on the position data from the retrofitted position determining device. In any case, the computing unit 60 may be provided in the control unit 100 as shown in FIG. 6 or externally connected to the control unit 100. Shielding disk driver position measuring device: The shielding disk driver position measuring device may be configured by the components as exemplified in the following: (1) Storage unit: If the shielding disk drive mechanism 30 is positioned at a certain position, the shielding disk driver position measuring device may comprise a storage unit 50 for storing position data provided by having previously measured any position of the shielding disk drive mechanism 30 relative to the common reference point CSP, in this embodiment, any particular standard position MSP in the shielding disk movement plane SMP, which position will be referred to “in-movement-plane standard position MSP”. (2) X-ray source position data: If the shielding disk drive mechanism 30 is mounted on the X-ray generator 3 at a predetermined relative position (or a previously measured positional relationship) relative to the X-ray source S the position of which can be measured as described above, the shielding disk driver position measuring device may also comprise the X-ray source S, a storage unit 50 for storing any relative position data between any position of the shielding disk drive mechanism 30 and the in-movement-plane standard position MSP (as in this embodiment), and the aforementioned X-ray source position measuring device. (3) Bed position data: If the shielding disk drive mechanism 30 is mounted on a bed 9 at a predetermined relative position (or a previously measured positional relationship) relative to the bed 9 the position of which can be measured as described above, the shielding disk driver position measuring device may further comprise the bed 9, a storage unit 50 for storing relative position data between any position of the shielding disk drive mechanism 30 and the in-movement-plane standard position MSP (as in this embodiment), and means for measuring the position of the bed 9. (4) Three-dimensional image measuring device based on video cameras: The shielding disk driver position measuring device may still further comprise reflective measurement markers (not shown) mounted on the shielding disk drive mechanism 30 and used for measuring previously the standard position (posture) of the shielding disk drive mechanism 30, a lighting apparatus (not shown) for illuminating the markers, a camera system having two video cameras 300A and 300B (FIG. 18) for imaging the markers, and a computing unit 60 for computing or determining the position/posture of the shielding disk drive mechanism 30 based on the image data of the imaged markers. Such a three-dimensional image measuring arrangement based on video cameras may be in the form of any known position measuring system incorporated into a general motion capturing device, and the detailed structure and operation thereof will not be described further in detail herein. In either of the aforementioned four cases, the storage unit 50 and computing unit 60 may be provided in the control unit 100 as shown in FIG. 6 or externally connected to the control unit 100. Eyeball position measuring device: The eyeball position measuring device may be configured by the components as exemplified in the following: (1) Laser pointer: The eyeball position measuring device may comprise a laser pointer for positioning an eyeball EB at the previously measured or predetermined position relative to the common reference point CSP, and a storage unit 50 for storing the position data of this predetermined position. The storage unit 50 may be provided in the control unit 100 as shown in FIG. 6 or externally connected to the control unit 100. Such a laser pointer may be in the form of a well-known imaging/positioning laser pointer which has been used for diagnosis by means of an X-ray computed tomography system, and the structure and operation thereof will not be described herein. Alternatively, the eyeball position measuring device may be configured by a well-known imaging/positioning laser pointer with measuring function which has been used for diagnosis in an X-ray computed tomography system. Such a laser pointer is also a well-known device which has been used for diagnosis in an X-ray computed tomography system. By using such a device, the position of an eyeball EB relative to the common reference point CSP can be measured. (2) Bed position data: If the bed 9 is of power driven type comprising an encoder or the like which can output the position data of the bed 9, the eyeball position measuring device may also comprise the encoder or the like, and a computing unit 60 for computing or determining the position of an eyeball relative to the common reference point CSP based on the position data of the bed from said encoder or the like and also the previously measured distance between the back of the head of a patient PA supported on the bed 9 and the eyeball. If an even movable bed 9 does not comprise means for outputting the position data of the bad 9, the eyeball position measuring device can comprise a retrofitted bed position measuring device comprising a linear encoder, an inclination sensor or the like which is retrofitted on the bed 9 for measuring the position of the bed 9, and a computing unit 60 for computing or determining the position of an eyeball relative to the common reference point CSP based on the bed position data from the retrofitted bed position measuring device and also the previously measured distance between the back of the head of a patient PA supported on the bed 9 and the eyeball. In any case, the computing unit 60 may be provided in the control unit 100 as shown in FIG. 6 or externally connected to the control unit 100. (3) Angiographic system: The eyeball position measuring device may further comprise an X-ray fluoroscopic apparatus used as the angiographic system 1, and a computing unit 60 for computing the position of the eyeball relative to the common reference point CSP based on data provided by using the X-ray fluoroscopic apparatus to image the head of a patient PA in two different directions while changing the rotation angle of the arm 2 on which the X-ray generator 3 and X-ray detector 4 are mounted, as shown in FIG. 11 so as to determine the positions of pixels at a location at which an eyeball EB is imaged on each of the visualized images, and to determine coordinates of points B and D on the X-ray detector 4 on which the eyeball EB is imaged, from the actual size of each pixel and the coordinates of the center of the X-ray detector 4. This computing unit 60 may also be provided in the control unit 100 or externally connected to the control unit 100. As shown in FIG. 11, the computing unit 60 computes the coordinates (X, Y, Z) of an intersection E at which the eyeball is positioned, by use of the following equations (1) and (2) as to the straight lines AB and CD, respectively, based on the coordinates of the points B and D determined by the angiographic system 1.X=x1+s(x3−x1), Y=y1+s(y3−y1), Z=z1+s(z3−z1) (1)X=x2+t(x4−x2), Y=y2+1t(y4−y2), Z=z2+t(z4−z2) (2) That is to say, the coordinates of the intersection E are determined by substituting constants for x, y and z in the equations to solve them for “s” and “t”. If the aforementioned operation is performed to each of the eyeballs, the coordinates (X, Y, Z) of the intersection E at which each eyeball is located can be determined. (4) Three-dimensional image measuring device based on a video camera: The eyeball position measuring device may further comprise reflective measurement markers (not shown) located near each of the eyeballs, a lighting apparatus (not shown) for illuminating the markers, a camera system having two video cameras 300A and 300B (FIG. 18) for imaging the markers, and a computing unit 60 for computing or determining the position of each eyeball based on the image data of the imaged markers. Such a three-dimensional image measuring arrangement based on video cameras may be in the form of any known position measuring system incorporated into any general motion capturing device, and the structure and operation thereof will not be described further in detail herein. Computing unit: According to this embodiment, the computing unit 60 is adapted to compute or determine an intersection point between the shielding disk movement plane in which the shielding disk 20 is moved and a central line C extending through the X-ray source S and the center EBC of an eyeball EB, namely, a shielding position SH, based on the data from the X-ray source position measuring device, the data from the eyeball position measuring device and the data from the shielding disk driver position measuring device. According to this embodiment, the computing unit 60 determines the central line extending through the X-ray source S and the center EBC of an eyeball EB by use of the following equation (3) where the position of the X-ray source S is in a point (x1, y1, z1) and the position EBC of an eyeball is in a point (x2, y2, z2).x=x1+s(x2−x1), y=y1+s(y2−y1), z=z1+s(z2−z1) (3) On the other hand, the computing unit 60 determines the shielding disk movement plane by use of the following equation (4):a(x−x3)+b(y−y3)+c(z−z3)=0 (4)where the position of the shielding disk drive mechanism (or the in-movement-plane standard position as in this embodiment) is in a point (x3, y3, z3), since the normal vector (a, b, c) of the shielding disk movement plane can be calculated by the shielding disk movement plane being parallel to the projection plane P. By substituting the equation (3) for the equation (4) to solve for “s,” the coordinates of the intersection point (i.e., the shielding position SH) can be determined. The control unit 100 controls the shielding disk drive mechanism 30 so that a shielding disk 20 (or the center thereof) will be moved to be centered on the shielding position SH determined by the computing unit 60. As described, the position of the shielding disk 20 (or the center thereof) in the shielding disk drive mechanism 30 is determined by the computing unit 60 based on the positional information of the first and second sliding members 33, 35 provided by the first and second stepping motors 33A, 35A. The control unit 100 controls the shielding disk drive mechanism 30 according to the position data of this shielding disk 20 (or the center thereof). Shielding disk size determining means: The X-ray shield device also comprises a shielding disk size determining means for computing or determining the size (e.g., diameter) of a circular shielding disk 20 suitable for a particular part of a patient PA at which the irradiation of X-ray from the X-ray source S should be blocked, that is, an eyeball in case of the intravascular procedure to be performed against the head of the patient PA. In the present application, the size of the circular shielding disk 20 suitable for the particular part of the patient PA at which the X-ray irradiation from the X-ray source S should be blocked is understood to refer to one that can block the X-ray from the X-ray generator to any desired part of a human body at which the X-ray irradiation should be avoided while permitting the X-ray irradiation to be irradiated to another part of the human body which needs the X-ray irradiation from the X-ray generator. For convenience sake, the following description will similarly be made assuming that the particular part of the patient PA at which the X-ray irradiation from the X-ray source S should be blocked is one of eyeballs EB of the patient. The shielding disk size determining means comprises the above described shielding position determining means, an eyeball size storing device for storing data relating to the size of an eyeball projected onto a plane EBP perpendicular to the center line C which passes through the X-ray source S and the center of the eyeball EB, and a computing unit 60 for computing or determining the diameter of a shielding disk 20 suitable for the eyeball EB based on data provided from the shielding position determining means and eyeball size storing device. Eyeball size storing device: The eyeball size storing device may be configured by a storage unit for storing any numerical data (e.g., 24 mm for adult) such as numerical data commonly indicative of an anatomically ocular diameter or numerical data that is an average ocular diameter as the size of an eyeball EB projected onto the plane EBP perpendicular to the center line C which extends through the X-ray source S and the center of the eye ball EB. Computing unit: The computing unit 60 computes or determines the diameter (d) of a shielding disk 20 suitable for each eyeball to be shielded, based on the data from the aforementioned shielding position determining means and eyeball size storing device. For better understanding of the present invention, FIG. 12 schematically illustrates the relationship between the X-ray source position S, the eyeball position EBC and the shielding position SH. In accordance with this embodiment, the computing unit 60 uses the following equation (5) to determine the diameter (d) of a shielding disk 20.d=(Distance between the X-ray source position S and the shielding position SH)/(Distance between the X-ray source place S and each eyeball position EBC)×the diameter of an eyeball (5)In other words, the diameter (d) of the corresponding shielding disk 20 can be determined according to the following equation 6):d=√{(x2−x1)2+(y2−y1)2+(z2−z1)2}/√{(x3−x1)2+(y3−y1)2+(z3−z1)2×the diameter of an eyeball (6)where the X-ray source position S is at (x1, y1, z1), the shielding position SH is at (x2, y2, z2) and the eyeball position EBC is at (x3, y3, z3). Operation of X-ray shield device: Operation of the aforementioned X-ray shield device will be described below. When the X-ray shield device is to be used, the following steps will be performed: measuring the position of the X-ray source S by the X-ray source position measuring device; measuring the position of the shielding disk drive mechanism by the shielding disk driver position measuring device; and measuring the position of each eyeball by the eyeball position measuring device or positioning each eyeball at a predetermined position. The sequence of these steps may be arbitrarily selected. The computing unit 60 calculates the shielding position SH at which each of the shielding disks 20 should be positioned, based on these results of measurement (data). Subsequently the computing unit 60 processes and determines the diameter of a shielding disk 20 suitable for each of the eyeballs EB, based on data relating to the size of that eyeball from the eyeball size storing device, data from the X-ray source position measuring device, data from the shielding disk driver position measuring device and data from the eyeball position measuring device. Based on this determination, a selected circular shielding disk 20 having its proper diameter is set on the supporting portion of the arm 36, 206A or 208A in the shielding disk drive mechanism 30 or 30A by the control unit 100 controlling the shielding disk drive mechanism 30 or 30A. This may be performed in a manual manner. Subsequently, the computing unit 60 computes or determines the current position of each of the shielding disks 20 in the shielding disk drive mechanism 30 based on the position information about the first and second sliding members 33, from the first and second stepping motors 33A, 35A. The control unit 100 controls the shielding disk drive mechanism 130 to move each of the shielding disks 20 (or the center thereof) from the current position to the corresponding shielding position SH. In this regard, the X-ray generator 3 may be moved while the X-rays are being emitted from the X-ray source S during use of the X-ray fluoroscopic apparatus 1. Even in such a case, however, the control unit 100 can control, according to the present invention, the shielding disk drive mechanism 30 such that the shielding disk 20 will be moved from the original shielding position SH to a new shielding position SH without discontinuation, in response to movement of the X-ray generator 3. The second embodiment of the X-ray shield device of the present invention is different from the first embodiment only in the structures of the shielding position determining means and shielding disk size determining means. Only the different structures will be described, and the structures and operations of the second embodiment similar to those of the first embodiment will be omitted. Only the components of the second embodiment different from those of the X-ray shield device according to the first embodiment will be described. Shielding position determining means: A shielding position determining means according to the second embodiment determines a shielding position SH on which an X-ray shielding disk 20 should be centered and at which a line extending centrally through the X-ray source S and a position PP of a projection image of an eyeball EB on the projection plane P, intersects the shielding plate movement plane SMP. The shielding position determining means comprises a shielding disk driver position measuring device, an X-ray source position measuring device, an eyeball image position measuring device for measuring the position of the image of an eyeball EB formed on the projection plane P of the X-ray detector 4 relative to the common reference point CSP, and a computing unit 60 for computing or determining the shielding position SH based on data from the shielding disk drive mechanism position measuring device, data from the X-ray source position measuring device and data from the imaged eyeball position measuring device. The shielding disk driver position measuring device and X-ray source position measuring device in the shielding position determining means of the X-ray shield device according to the second embodiment are identical with those of the first embodiment. On the other hand, the X-ray shield device of the second embodiment is different from that of the first embodiment in that it has the eyeball image position measuring device and that the computing unit 60 computes the shielding position SH of each shielding disk 20. Projected eyeball image position measuring device: The projected eyeball image position measuring device comprises a projection plane position measuring device for measuring any point (“projection reference point PSP”) in the projection plane P relative to the common reference point CSP, a lateral projected eyeball image position measuring device for measuring the position of an eyeball in the X-Y axis relative to the projection reference point PSP in the projection plane P, and a computing unit 60 for computing the position of the projected eyeball image (or the center thereof) (“projected eyeball image position PP”) based on data from the projection plane position measuring device and lateral projected eyeball image position measuring device. FIG. 13 schematically illustrates the relationship between the common reference point CSP, the projection reference point PSP and the projected eyeball image position PP. In this figure, arrows A and C indicate position vectors on the basis of the common reference point CSP while an arrow B indicates a position vector on the basis of the projection reference point PSP. Projection plane position measuring device: The projection plane position measuring device may be configured by the components as exemplified in the following: (1) Position output means of the angiographic system 1: If each of the aforementioned motors 6A, 7C, 8A and 8B in the angiographic system 1 is provided with a position output means such as an encoder which can output the positional data of the corresponding movable part moved by the corresponding one of these motors in the angiographic system 1, the projection plane position measuring device may comprise such a position output means, and a computing unit 60 for computing or determining the position of the projection plane P based on the positional data outputted from said position output means. (2) Position measuring device to be retrofitted: If each of the motors 6A, 7C, 8A and 8B of the angiographic system 1 is not provided with position output means such as an encoder which can output the position data of the corresponding movable part moved by that motor in the angiographic system 1, the projection plane position measuring device may comprise a retrofit position measuring device for measuring the position of the movable part in the angiographic system 1 such as a linear encoder or inclination sensor retrofitted to that movable part and a computing unit 60 for computing or determining the position of the projection plane P based on the positional data from the retrofit position determining device. In either of the above two cases, the computing unit 60 may be provided in the control unit 100 as shown in FIG. 6 or externally connected to the control unit 100. Lateral projected eyeball image position measuring device: The lateral projected eyeball image position measuring device may be configured by the components as exemplified in the following: (1) Contact lens markers: As shown in FIG. 14, the lateral projected eyeball image position measuring device may comprise contact lenses CL each of which is mounted on an eyeball EB and which includes a marker M embedded therein and made of an X-ray shieldable material such as lead or tungsten, means for computing or determining the position M1 of each pixel in the projected image of each of the markers M on the projection plane P of the detector 4 in the angiographic system 1 through the pattern matching technique for image processing when the angiographic system 1 x-rays or visualizes fluoroscopically a patient PA which includes a contact lens CL mounted thereon at each eyeball, and a computing unit 60 for computing the lateral position M2 of the projected image of each marker (i.e., each eyeball EB) in the projection plane P based on the actual size per pixel of the fluoroscopic projected image. In place of the contact lenses CL, each of the markers M may be mounted on an eye patch (which preferably includes any adhesive material), such an eye patch being then mounted on the eyelid of a patient. The markers may be of any geometric shape, e.g., a star-like shape. (2) Markers: As shown in FIG. 15, the lateral projected eyeball image position measuring device may comprise markers M (preferably including any adhesive material) which are mounted on any distinctive part of the human body such as nose, ear, parietal region or chin other than the eyes (or eyeballs EG) and which are made of any suitable X-ray shielding material, means for computing or determining the pixel positions M1 of the images of the markers M projected onto the X-ray fluoroscope plane P through the pattern matching technique for image processing, and a computing unit 60 for computing or determining an estimated position M3 of each eyeball EB from data relating to the matched position M2 of each of these nose, ear, parietal region and chin and data relating to the relative position between each eyeball EB and any one of the nose, ear, parietal region and chin, the last-mentioned data having been previously stored or accumulated in the storage unit 50 and also for computing the lateral position M4 of the projected image of each eyeball EB in the projection plane P based on the actual size per pixel in the fluoroscopic projected image. Computing unit: According to the second embodiment, the computing unit 60 is adapted to compute or determine an intersection point (shielding position SH) between the shielding disk movement plane SMP in which the shielding disk 20 is moved and the center line C extending through the X-ray source S and the center PP of the position onto which each eyeball is projected, based on data from the shielding disk driver position measuring device, data from the X-ray source position measuring device and data from the projected eyeball image position measuring device. According to the second embodiment, the computing unit 60 first determines a center line C extending through the X-ray source S and the center PP of the projected eyeball image by use of the following equation (7):x=x1+s(x2−x1), y=y1+s(y2−y1), z=z1+s(z2−z1) (7)where the X-ray source S is at (x1, y1, z1), the position PP of the projected image of each eyeball is at (x2, y2, z2), as schematically illustrated in FIG. 16. In FIG. 16, arrows A, B and C indicate position vectors on the basis of the common reference point CSP. According to the second embodiment, the computing unit 60 can then compute a shielding disk movement plane SMP using the following equation (8):a(x−x3)+b(y−y3)+c(z−z3)=0 (8)where the position MSP of the shielding disk drive mechanism (or an origin in the shielding disk movement plane SMP) is at (x3, y3, z3), since the normal vectors (a, b, c) of the shielding disk movement plane SMP can be computed from the fact that the shielding disk movement plane is parallel to the projection plane P. By substituting the equation (7) for the equation (8) to solve for “s”, the coordinates (position) of the intersection point (i.e., the shielding position SH) can be determined. Shielding disk size determining means: The shielding disk size determining means according to the second embodiment comprises the shielding position determining means as described above in connection with the second embodiment, a projected eyeball image size measuring device for measuring the size of the projected image of each eyeball EB in the projection plane P of the X-ray detector 4, and a computing unit 60 for computing or determining the size of a shielding disk 20 suitable for that eyeball EB based on data from the shielding position determining means and projected eyeball image size measuring device. Projected eyeball image size measuring device: The projected eyeball image size measuring device may be configured by the components as exemplified in the following: (1) Image measuring means in the angiographic system 1: The projected eyeball image size measuring device may be comprise means for measuring the pixel size of the projected image of each eyeball of a patient on the projection plane P of the detector 4 of the angiographic system 1 by use of an image measuring/processing technique utilized by the angiographic system and for measuring the size of the projected eyeball image by multiplying the actual size per pixel of the fluoroscopic projected image and the pixel size of the projected eyeball image together. (2) Image processing unit to be retrofitted: If the angiographic system 1 does not include an image processing means which can measure the pixel size of the projected image, the projected eyeball image size measuring device may comprise a retrofitted image processing unit for measuring the size of the projected eyeball image by use of an image processing/measuring technique and means for measuring the size of the projected eyeball image by distributing and inputting monitored image signals from the X-ray fluoroscopic apparatus into the image processing unit, measuring the pixel size in the projected eyeball image by use of the image processing/measuring technique and multiplying the actual size per pixel of the fluoroscopic projected image and the pixel size of the projected eyeball image together. (3) Contact lens markers or Image processing unit using the contact lens markers: The projected eyeball image size measuring device may comprise means for computing or determining the size of a projected eyeball image by comparing the pixel size in the projected image of each eyeball of a patient in the projection plane P of the detector 4 of the angiographic system with the pixel size of the projected image of a contact lens marker mounted directly on each eyeball and having its known size or a contact lens marker mounted near each eyeball and having its known size in the projection plane P. Computing unit: According to the second embodiment, the computing unit 60 determines the size (diameter) (d) of a shielding disk 20 suitable for each eyeball EB based on the aforementioned data by use of the following equation (9):d=(Distance between the X-ray source position S and the shielding position SH)/(Distance between the X-ray source place S and the position PP of each of the projected eyeball images)×the diameter of a projected eyeball image (9) In other words, the diameter (d) of the corresponding shielding disk 20 can be determined according to the following equation (10):d=√{(x2−x1)2+(y2−y1)2+(z2−z1)2}/√{(x3−x1)2+(y3−y1)2+(z3−z1)2}×the diameter of a projected eyeball image (10)where the X-ray source position S is at (x1, y1, z1), the shielding position SH is at (x2, y2, z2) and the position of projected eyeball image PP is at (x3, y3, z3). The position of projected eyeball image PP relative to the common reference point CSP can be determined based on the projection reference point PSP in the projection plane P provided by the projection plane position measuring device and on the lateral position data of each eyeball EB in the projection plane P provided by the lateral projected image position measuring device. Shielding performance test was performed using an angiographic system available from Toshiba (Trade Name, Circulatory Organ Imager, model/KXO-100G), in which shielding disks 20 each having its diameter of 1.0 cm were respectively mounted on the arm 36 of the shielding disk drive mechanism 30 in the X-ray shield device constructed according to the present invention. The shielding disks 20 were of two types, one comprising a layered product consisted of an iron sheet having its thickness of 0.5 mm and a lead sheet having its thickness of 3.0 mm (Example 1) and another comprising a layered product consisted of an iron sheet having its thickness of 0.5 mm and a lead sheet having its thickness of 6.0 mm (Example 2). For comparison with these shielding disks 20, the shielding performance test was also performed without shielding disk. The angiographic system was used with a voltage of 80 kV and a current of 125 mA in an X-ray tube used. Three thermo-luminescence dosimeters (170A) were arranged on the right crystalline lens of RANDO™ phantom which was made of a material radiologically equivalent to the human body tissue. X-rays were irradiated for one minute so that they arrived at the right eye through the back of the head. In Examples 1 and 2, each of the shielding disks 20 had its center that was on a center line passing through the centers of the tubular lamp and right crystalline lens and that was spaced apart from the tubular lamp by a distance of 45 cm. The center of the right crystalline lens was disposed to be on said center line and to be spaced apart from the tubular lamp by a distance of 92 cm. Furthermore, the distance between the tubular lamp and an image [picture] multiplier was 122 cm. Test results are shown in Table 1. TABLE 1No shieldingExample 1Example 2diskRight Crystalline Lens8.838.1913.56 It could be observed from the results of the aforementioned experiments that the shielding effect relating to the right crystalline lenses each of which was covered with the shielding disk 20 to shield the X-rays was increased by about 35% more than without shielding disk in Example 1 and as much as about 39% more than without shielding disk in Example 2. The present invention is not limited to the aforementioned embodiments, and various modifications thereto can be made as will be described below. For example, two or more radioparent arms 36 may be used although the embodiment described in connection with FIG. 5 includes only one radioparent arm 36. In this case, it is preferred that the arms are controlled independently. Alternatively, a single radioparent arm 36 may be of bifurcated type, for example, so that it can hold two X-ray shielding disks 20. If such a bifurcated arm 36 is to be used for shielding the eyeballs, it is preferable to set the distance between two shielding disks 20, for example, at the average distance between eyeballs. Furthermore, the shielding disk drive mechanism 30A shown in FIG. 7 can cause two X-ray shielding disks 20 independently to move such that both the eyes of a patient can be shielded against X-rays. Typically, X-rays may be irradiated to one temporal region of a patient PA if the X-ray generator 3 and X-ray detector 4 are located horizontally. In such a case, a single X-ray shielding disk 20 is sufficient to shield one eyeball of the patient against X-rays. If another X-ray shielding disk 20 is used, it may block the irradiation of X-rays to any necessary part. In order to overcome such a problem, two shielding disk drive mechanisms 30A may be provided such that two X-ray shielding disks 20 can be moved in the respective distinct movement planes. In such a case, the two X-ray shielding disks 20 may be positioned on the same path of X-radiation (the same X-rays axis) at the same time. Alternatively, a plurality of shielding disk drive mechanisms 30A may be provided to move three or more X-ray shielding disks 20 in the respective different movement planes. Although the embodiments of the present invention have been described in connection with the angiographic systems with which the X-ray shield devices according to the present invention may be used, any one of the X-ray shield devices according to the present invention may find application in any radiographic equipments other than the angiographic systems. Furthermore, the X-ray shield devices according to the present invention may be used to shield any radiation other than X-ray. LIST OF REFERENCE NUMERALS 1fluoroscopic apparatus 2X-ray source 3X-ray generator 4X-ray detector 9bed (support member) 20X-ray shielding disk 30shielding disk driving mechanism 32Ax-axis guide 33first slider 33Afirst stepping motor (first motor means) 34y-axis guide 35second slider 35Asecond stepping motor (second motor means) 36radioparent arm100control unit
	claims	1. A topical composition to protect skin against contact with metal irritants and allergens that comprises, at least one metal capturing agent bearing carboxyl moieties, and further comprising from 10% to 25% of the total weight of the composition of an agent chosen among zeolite, hydroxyapatite, calcium carbonate, calcium phosphate, ammonium calcium silicate, microporous aluminosilicate, sodium aluminosilicate, calcium silicate, sodium calcium aluminosilicate, and magnesium carbonates, tricalcium silicate, magnesium phosphate, manganese carbonate;wherein the carboxyl bearing agent is a carbomer, present in an amount ranging from 0.1 to 10% of the total weight of the composition, andwherein the topical composition has a pH of from 4 to 8. 2. A topical composition according to claim 1, wherein the metal irritant or allergens is a metal cation. 3. A topical composition according to claim 1, wherein the metal irritant or allergen is nickel, cobalt, chromium, zinc or lead. 4. A topical composition according to claim 1, as a medicament. 5. A topical composition according to claim 1 for its use to reduce or prevent contact dermatitis. 6. A topical composition according to claim 1 for its use to prevent allergies to metals. 7. A topical composition according to claim 1 for its use to reduce undesired effects on skin following to contact with irritating metals. 8. A topical composition according to claim 1 for its use to limit risks induced by exposure to radioactive material. 9. A topical composition according to claim 8, wherein the radioactive material is uranium. 10. A topical composition according to claim 1, wherein the composition has a physiological pH. 11. A topical composition according to claim 1, wherein the composition has a pH of from 5.5 to 6.9.
059230401	claims	1. A wafer sample retainer for an electron microscope comprising: a rail; a base adjustably positionable along said rail; a sample holder removably connectable to said base, said holder having an upstanding post; an L-shaped spring biased member mounted for pivotal rotation on said holder, said member having first and second elements, said first element having a free end, said free end pivotal towards and away from said post against said spring biased member, said second element having a manually displaceable free end such that when said free end of said second element is manually displaced, said free end of said first element is displaced away from said post; and a sample retainer opening (slot) arranged between said post and said member to receive a wafer such that said wafer is spring biased against said post by said member when said member is not manually displaced and when said member is manually displaced, the spring bias of said member against said wafer is removed, allowing said wafer to be removed from said slot. 2. The retainer of claim 1 wherein said free end includes a rounded portion arranged to engage said sample. 3. The retainer of claim 1 wherein said spring biased member is adapted to secure a plurality of wafer samples to said post at one time. 4. The retainer of claim 1 wherein said spring biased member is L-shaped, having a pair of portions connected at a corner, said member being mounted for rotation about said corner, one of said portions being depressible to rotate the other of said portions towards and away from said post. 5. The retainer of claim 4 including pair of spring biased members each arranged to pivot towards and away from said post. 6. The retainer of claim 5 wherein each of said spring biased members is arranged to pivot towards and away from an opposite side of said post.
	abstract	An extreme ultraviolet light generation device is to generate extreme ultraviolet light by irradiating a target with a pulse laser beam and thereby turning the target into plasma. The device may include a chamber, a magnet configured to form a magnetic field in the chamber, and an ion catcher including a collision unit disposed so that ions guided by the magnetic field collide with the collision unit.
	claims	1. An intensifying screen for exposing X-ray film, the intensifying screen comprising:a screen support backing;a luminescent layer including a luminescent material that emits light in the presence of X-rays;a reflective layer disposed between the luminescent layer and the screen support backing, the reflective layer including a plurality of micro-prisms that reflect light emitted by the luminescent material,wherein micro-prism surfaces of the plurality of micro-prisms do not reflect light that impinges on the respective micro-prism surfaces at an angle exceeding a critical angle as measured from the respective micro-prism surfaces. 2. The intensifying screen according to claim 1, wherein the reflective layer is configured to reflect light emitted by the luminescent material toward an X-ray film disposed adjacent to the luminescent layer. 3. The intensifying screen according to claim 1, wherein the reflective layer reflects light in a direction generally perpendicular to a surface of the screen support backing facing the reflective layer. 4. The intensifying screen according to claim 1, wherein the reflective layer reflects light in a direction generally perpendicular to a surface of the luminescent layer facing the reflective layer. 5. The intensifying screen according to claim 1, wherein the luminescent layer emits visible light in response to excitation by X-rays. 6. The intensifying screen according to claim 1, wherein the luminescent material comprises a phosphor material. 7. The intensifying screen according to claim 1, wherein the reflective layer comprises a polymer material. 8. The intensifying screen according to claim 1, wherein the reflective layer comprises a crystalline material. 9. The intensifying screen according to claim 1, wherein the reflective layer comprises a glass material. 10. The intensifying screen according to claim 1, further comprising a light-absorbing layer on a side of the plurality of micro-prisms opposite the luminescent layer. 11. The intensifying screen according to claim 1, wherein the screen support backing comprises a light-absorbing layer. 12. An X-ray film cassette comprising:at least one intensifying screen according to claim 1;a housing surrounding the at least one intensifying screen. 13. The X-ray film cassette according to claim 12, wherein the X-ray film cassette includes two intensifying screens disposed on opposing inner surfaces of the housing. 14. An X-ray film assembly comprising:at least one intensifying screen according to claim 1;an X-ray film. 15. The X-ray film assembly according to claim 14, wherein the X-ray film is disposed between two intensifying screens. 16. The X-ray film assembly according to claim 14, wherein the X-ray film has an emulsion layer. 17. The intensifying screen according to claim 1, wherein the micro-prism surfaces reflect light that impinges on the respective micro-prism surfaces at an angle that is less than the critical angle as measured from the respective micro-prism surfaces. 18. The intensifying screen according to claim 1, wherein the micro-prism surfaces reflect light that impinges on the respective micro-prism surfaces at an angle that is less than the critical angle as measured from the respective micro-prism surfaces. 19. The intensifying screen according to claim 1, wherein light impinging on the micro-prism surfaces that is not reflected is refracted and passes through at least a portion of the reflective layer.
049960202	claims	1. A system for restraining diffusion of tritium, comprising a heat reserving means which is mounted to a device of a fast breeder reactor and which includes a hydrogen-absorbing metal. 2. A system for restraining diffusion of tritium as recited in claim 1, wherein said heat reserving means comprises an inner wall surrounding the device, a heat reserving material surrounding the exterior of the inner wall, and an outer wall surrounding the exterior of the heat reserving material, at least one of the inner and outer walls being made of the hydrogen-absorbing metal. 3. A system for restraining diffusion of tritium as recited in claim 1, wherein said heat reserving means comprises an inner wall surrounding the device, a heat reserving material surrounding the exterior of the inner wall, and an outer wall surrounding the exterior of the heat reserving material, at least one of the inner and outer walls being provided with the hydrogen-absorbing metal mounted thereto. 4. A system for restraining diffusion of tritium as recited in claim 1, wherein said heat reserving means comprises an inner wall surrounding the device, a heat reserving material surrounding the exterior of the inner wall, and an outer wall surrounding the exterior of the heat reserving material, said heat reserving material being made of the hydrogen-absorbing metal. 5. A system for restraining diffusion of tritium as recited in claim 1, wherein said heat reserving means comprises an inner wall surrounding the device, a heat reserving material surrounding the exterior of the inner wall, and an outer wall surrounding the exterior of the heat reserving material, said heat reserving material being provided with the hydrogen-absorbing metal mixed therewith. 6. A system for restraining diffusion of tritium as recited in claim 1, wherein said heat reserving means comprises an inner wall surrounding the device, a heat reserving material surrounding the exterior of the inner wall, and an outer wall surrounding the exterior of the heat reserving material, said heat reserving material being provided with the hydrogen-absorbing metal mixed therewith in the form of fiber, chip or powder. 7. A system for restraining diffusion of tritium as recited in claim 1, wherein said hydrogen absorbing metal is an alloy selected from the group consisting of Ti-Mn, Mg-Ni, Mg.sub.2 Ni, Mg.sub.2 Ni.sub.0.9 Cr.sub.0.1, LaNi.sub.5, MmNi.sub.5, MmCo.sub.5, MmNi.sub.4.5 Mn.sub.0.5, MmNi.sub.4.5, MmNi.sub.4.5, TiFe, TiCr, TiCr.sub.2, TiFe.sub.0.9 Nb.sub.0.1, Ti-Zr-Mn-Mo, Ti-Mn-Fe-V, Ti-Zr-Mn-Fe and CaNi.sub.5 in which Mm represents a misch metal consisting of a mixture of La, Ce, Pr, Nd and Sm. 8. A system for restraining diffusion of tritium as recited in claim 1, wherein said hydrogen-absorbing metal strains diffusion of the tritium by absorbing tritium occurring in the fast breeder reactor.
	description	The present disclosure relates to an ion beam irradiating apparatus, which irradiates a target with an ion beam (in the specification, a positive ion beam) extracted from an ion source, thereby performing ion implantation or another process, and also to a method of producing a semiconductor device with using the apparatus. In the case where ion implantation is performed, the ion beam irradiating apparatus is also called an ion implanter. In an ion beam irradiating apparatus which irradiates a target with an ion beam extracted from an ion source, thereby performing ion implantation or another process, it is desired to efficiently transport a low-energy and large-current ion beam from viewpoints such as that the throughput of the apparatus is improved, and that the ion implantation depth is reduced to cope with miniaturization of a semiconductor device to be formed on the target. As the energy of an ion beam is lower and the current of the beam is larger, however, dispersion of the ion beam due to space charge is further increased, and hence it is difficult to efficiently transport the ion beam. As one technique for solving the problem, a technique is known in which electrons are supplied from the outside to a transported ion beam and space charge of the ion beam is neutralized by the electrons. In this case, it is preferable to use an electron source which can generate a large amount of low-energy electrons because of reasons such as that negative charging of the surface of a target by the supplied electrons is suppressed. As an electron source which can generate a large amount of low-energy electrons, Japanese Patent Unexamined Publication No. 2005-26189 (Paragraphs 0007 to 0009, FIG. 1) (hereinafter referred as Patent Reference 1) discloses a field emission electron source. Namely, the publication discloses a technique in which a field emission electron source that can generate a large amount of low-energy electrons is placed in the vicinity of a target, electrons emitted from the field emission electron source are caused to be incident substantially perpendicularly on an ion beam from the lateral side of the ion beam, and charging (charge-up) of the surface of the target at ion-beam irradiation is suppressed. Although the charging suppression of a target surfaces disclosed in Patent Reference 1, and the neutralization of space charge of an ion beam are techniques for different objects, the inventors conceived that a field emission electron source such as disclosed in Patent Reference 1 is used in the neutralization of space charge of an ion beam, and researched the use. However, it was noted that, even when, in the same manner as the technique disclosed in Patent Reference 1, electrons emitted from a field emission electron source are incident substantially perpendicularly on an ion beam from the lateral side of the ion beam, the effect of the neutralization of space charge of the ion beam, and hence suppression of dispersion of the ion beam is small. This is caused because of the following reason. Even when electrons are incident as described above, most of the electrons are moved so as to pass through the ion beam or stride over the ion beam, by the kinetic energy of the electrons, and acceleration due to the positive beam potential of the ion beam. Therefore, the existence probability of the electrons in the ion beam is low. Accordingly, it is difficult to efficiently neutralize space charge of the ion beam. Therefore, it is an object of the invention to provide an apparatus which uses a field emission electron source, and which can efficiently neutralize space charge of an ion beam and effectively suppress dispersion of the ion beam due to the space charge. The ion beam irradiating apparatus of a first aspect of the invention comprises a field emission electron source which is disposed in a vicinity of a path of the ion beam, which emits electrons, and which has many minute emitters that are formed on a conductive cathode substrate, and that have a pointed shape, and extraction electrodes that surround respectively vicinities of tip ends of the emitters with forming a minute gap, and the field emission electron source is placed in a direction along which an incident angle formed by electrons emitted from the electron source 10 and a direction parallel to a traveling direction of the ion beam is in a range from −15 deg. to +45 deg. (an inward direction of the ion beam is +, and an outward direction is −). When the field emission electron source is placed in the above-mentioned direction, and the incident angle of electrons emitted from the field emission electron source with respect to the ion beam is set to the above-mentioned range, the existence probability of the electrons in the ion beam is increased. As a result, space charge of the ion beam can be efficiently neutralized and dispersion of the ion beam due to the space charge can be effectively suppressed. In a second aspect of the invention, the incident angle is preferably in a range from −15 deg. to +30 deg. More preferably, in a third aspect of the invention, the incident angle is in a range from substantially 0 deg. to +15 deg. Most preferably, in a fourth aspect of the invention, the incident angle is substantially 0 deg. In a fifth aspect of the invention, the field emission electron source may be placed in a direction along which electrons are emitted toward a downstream side of the traveling direction of the ion beam. Alternatively, in the sixth aspect of the invention, the field emission electron source may be placed in a direction along which electrons are emitted toward an upstream side of the traveling direction of the ion beam. The field emission electron source may be placed on one side of the path of the ion beam. Alternatively, in a seventh aspect of the invention, the field emission electron source may be placed on both sides of the path of the ion beam. In an eighth aspect of the invention, in the case where, at the position of the field emission electron source, the ion beam has a shape in which a dimension of a Y direction in a plane intersecting with the traveling direction X is larger than a dimension of a Z direction perpendicular to the Y direction, preferably, the field emission electron source has a shape which extends in the Y direction. In a ninth aspect of the invention, while the target is a semiconductor substrate, and the semiconductor substrate is irradiated with the ion beam by using the ion beam irradiating apparatus to perform ion implantation, plural semiconductor devices may be produced on the semiconductor substrate. According to the first aspect of the invention, when the field emission electron source is placed in the above-mentioned direction, and the incident angle of electrons emitted from the field emission electron source with respect to the ion beam is set in the above-mentioned range, the existence probability of the electrons in the ion beam is increased. Therefore, space charge of the ion beam can be efficiently neutralized and dispersion of the ion beam due to the space charge can be effectively suppressed. As a result, the transport efficiency of the ion beam can be improved. According to the second aspect of the invention, when the incident angle is set in the above-mentioned range, space charge of the ion beam is more efficiently neutralized by electrons emitted from the field emission electron source, and dispersion of the ion beam due to the space charge can be more effectively suppressed. As a result, the transport efficiency of the ion beam can be more improved. According to the third aspect of the invention, when the incident angle is set in the above-mentioned range, space charge of the ion beam is further efficiently neutralized by electrons emitted from the field emission electron source, and dispersion of the ion beam due to the space charge can be further effectively suppressed. As a result, the transport efficiency of the ion beam can be further improved. According to the fourth aspect of the invention, when the incident angle is substantially 0 deg., space charge of the ion beam is further efficiently neutralized by electrons emitted from the field emission electron source, and dispersion of the ion beam due to the space charge can be further effectively suppressed. As a result, the transport efficiency of the ion beam can be further improved. According to the fifth aspect of the invention, when the field emission electron source is placed with being directed toward the downstream side, the field emission electron source can be placed with being separated upstream from the target, so that dispersion of the ion beam can be effectively suppressed over a long distance to the target. According to the sixth aspect of the invention, when the field emission electron source is placed with being directed toward the upstream side, space charge of the ion beam can be efficiently neutralized by electrons emitted from the field emission electron source, and dispersion of the ion beam due to the space charge can be effectively suppressed. In addition, electrons emitted from the field emission electron source are hardly incident on the target. Therefore, a further effect that negative charging of the surface of the target by the electrons is suppressed is attained. This is particularly effective in the case where the energy of electrons emitted from the field emission electron source is not very low. According to the seventh aspect of the invention, the field emission electron source is placed on both sides of the path of the ion beam, so that electrons can be supplied to the ion beam from the both sides of the ion beam. Therefore, space charge of the ion beam is further efficiently neutralized, and dispersion of the ion beam due to the space charge can be further effectively suppressed. According to the eighth aspect of the invention, the field emission electron source has a shape which extends in the Y direction. Even when the ion beam has a shape extending in the Y direction through or not through scanning in the Y direction, therefore, space charge of the ion beam can be neutralized more efficiently over a wider range of the ion beam. According to the ninth aspect of the invention, plural semiconductor devices can be produced on a semiconductor substrate by using an ion beam in which space charge is neutralized, and which is less dispersed. Therefore, plural semiconductor devices having uniform characteristics can be produced on the same semiconductor substrate. As a result, the yield is improved, and the production efficiency of a semiconductor device is enhanced. 1 ion source 2 ion beam 4 target 6 holder 10 field emission electron source 12 electron 16 cathode substrate 18 emitter θ incident angle FIG. 1 is a schematic side view showing an embodiment of the ion beam irradiating apparatus of the invention. The ion beam irradiating apparatus is configured so that a target 4 held by a holder 6 is irradiated with an ion beam 2 extracted from an ion source 1 to perform a process such as ion implantation on the target 4. The holder 6 is at, for example, the ground potential. The transporting path of the ion beam 2, and the holder 6 are placed in a vacuum chamber which is not shown, to be in a vacuum atmosphere. For example, the target 4 is a semiconductor substrate, a glass substrate, or the like. In the transporting path of the ion beam 2 extending from the ion source 1 to the holder 6, as required, a mass separator which separates the mass of the ion beam 2, a scanner which performs a scanning operation on the ion beam 2, and the like are disposed. Field emission electron sources 10 which emit electrons 12 are disposed in the vicinity of the path of the ion beam 2. In the embodiment, the field emission electron sources 10 are placed in a direction along which the electrons 12 are emitted toward the downstream side of the traveling direction X of the ion beam 2. The field emission electron sources 10 are on the both sides (both sides in the Z direction) of the path of the ion beam 2. At the positions of the field emission electron sources 10, the ion beam 2 may have a spot-like section shape, or a so-called ribbon like (this is called also a sheet-like or a strip-like) shape in which, as in an example shown in FIG. 2, the dimension of the Y direction in a plane intersecting with the traveling direction X of the ion beam 2 is larger (specifically, sufficiently larger) than that of the Z direction intersecting with the Y direction. The ribbon-like shape does not mean a shape which is paper-thin. The ribbon-like ion beam 2 may be caused to have a ribbon-like shape by reciprocally scanning a spot-like ion beam 2a such as shown in FIG. 2 in the Y direction, or may have a ribbon-like shape in a state where the ion beam is extracted from the ion source 1 without performing scanning. In the embodiment, the target 4 is reciprocally driven together with the holder 6 in a mechanical manner by a target driving apparatus 8 in a direction intersecting with the Y direction (i.e., a direction along the Z direction, or that inclined therefrom). The width in the Y direction of the ion beam 2 is slightly larger than that in the same direction of the target 4. This and the above-described reciprocal driving enable the whole face of the target 4 to be irradiated with the ion beam 2. The Y direction may be the horizontal direction, the vertical direction, or a direction inclined therefrom. As shown in FIG. 3 which enlargedly shows a part of the field emission electron source 10, the electron source 10 comprises: a conductive cathode substrate 16; many minute emitters 18 which are formed in the surface of the cathode substrate 16, and which have a pointed shape; an extraction electrode (also called a gate electrode) 22 which surrounds vicinities of the tip ends of the emitters 18 with forming minute gaps 26 therebetween, and which is common to the emitters 18; and an insulating layer 20 which is disposed between the extraction electrode 22 and the cathode substrate 16 to insulate them from each other. The cathode substrate 16 and the emitters 18 are electrically conductive with one another. Each of the emitters 18 has a sharp pointed-shape. In other words, the emitter has a shape which is more pointed as further advancing toward the tip end. In the example shown in FIG. 3, the emitters have a conical shape, or alternatively may have a pyramidal shape or the like. The extraction electrode 22 has minute holes 24 at positions corresponding to the emitters 18. Each of the minute holes 24 has, for example, a circular shape. At a center portion of the minute hole 24, a vicinity of the tip end of the corresponding emitter 18 is positioned with forming the minute gap 26 between the emitter 18 and the inner wall of the minute hole 24. The height of each of the emitters 18, the diameter D3 of a basal portion, the diameter of each of the minute holes 24, and the diameter of each of the gaps 26 have a minute size in unit of μm. The thus configured emitters 18 are formed in a large number on the cathode substrate 16. The large number is not a number of several tens to several hundreds, but simply speaking is at least about ten thousand or more. Specifically, as shown in FIG. 2, each of the field emission electron sources 10 in the embodiment has plural electron source arrays 14, and each of the electron source 10 arrays 14 has about ten to twenty thousand emitters 18. The number of the electron source 10 arrays 14 constituting each field emission electron source 10 is not restricted to three shown in FIG. 2. Referring again to FIG. 3, a DC extraction power source 32 which applies an extraction voltage V1 for extracting the electrons 12 from the emitters 18 by means of field emission is connected between the cathode substrate 16 of the field emission electron source 10 and the extraction electrode 22, while setting the extraction electrode 22 to the positive side. For example, the extraction voltage V1 is about 50 to 100 V. As required, as shown in the example of FIG. 3, an energy adjusting power source 36 which adjusts the energy of the electrons 12 to be emitted from the field emission electron source 10 may be connected between the cathode substrate 16 and the ground potential. For example, the output voltage V3 of the power source is about 0 to 50 V. The field emission electron source 10 can emit the electrons 12 at the extraction voltage V1 which is low as described above, and hence can emit the electrons 12 of a low energy. Moreover, the electron source 10 has the many emitters 18, and therefore can generate a large amount of electrons 12. For example, one electron source array 14 can generate electrons 12 of about 100 μA to 1 mA. When the electron source 10 is provided with plural electron source arrays 14, the electron source 10 can generate electrons 12 of an integer multiple of the number of the arrays. The field emission electron source 10 has a structure similar to that of a semiconductor device, and hence can be extremely miniaturized. Moreover, the electron source 10 can be operated while being placed in a vacuum chamber which maintains the path of the ion beam 2 to a vacuum atmosphere. Therefore, the field emission electron source 10 can be placed very close to the path of the ion beam 2. As in an example shown in FIG. 4, the field emission electron source 10 may further comprise a second extraction electrode 28 which is on the side of the emission side of the electrons 12 with respect to the extraction electrode 22, which extends along the extraction electrode 22, and which has many minute holes 30. The extraction electrodes 22, 28 are electrically insulated from each other via a space or an insulating layer or the like which is not shown. A DC second extraction power source 34 which applies a second extraction voltage V2 for adjusting the energy of the electrons 12 to be emitted from the field emission electron source 10 is connected between the cathode substrate 16 and the second extraction electrode 28. When V2>V1, the electron source 10 is operated in an acceleration mode in which the energy of the emitted electrons 12 is further increased, and, when V2<V1, the electron source 10 is operated in a deceleration mode in which the energy of the emitted electrons 12 is further decreased. As shown in FIG. 5, an angle θ of the electrons 12 emitted from the field emission electron source 10 with respect to a direction 40 which is parallel to the traveling direction X of the ion beam 2 is called an incident angle. The incident angle θ is set while the inward direction of the ion beam 2 is + (positive), and the outward direction is − (negative). The field emission electron source disclosed in Patent Reference 1 is placed in a direction along which the incident angle θ is about 90 deg. By contrast, in the embodiment, the field emission electron sources 10 are placed in a direction along which the incident angle θ is, for example, in a range from about −15 deg. to +45 deg. The field emission electron sources 10 can be placed in a direction of the incident angle θ which is sufficiently smaller than 90 deg. as described above because of the following reason. As described above, the field emission electron sources 10 can be extremely miniaturized, and operated in a vacuum atmosphere. Therefore, the field emission electron sources 10 can be placed very close to the path of the ion beam 2. Even when the electrons 12 are emitted from the field emission electron sources 10 at the above-described small incident angle θ, a positive beam potential Vp produced by the ion beam 2 exists in the ion beam 2 and in the periphery thereof. Accordingly, the electrons 12 are pulled into the ion beam 2 by the beam potential Vp to contribute to the neutralization of space charge of the ion beam 2. Furthermore, when the incident angle θ of the electrons 12 at the emission from the field emission electron sources 10 is set within the above-described range, the possibility that the electrons 12 are moved so as to pass through the ion beam 2 or stride over the ion beam 2 is lowered, and therefore the existence probability of the electrons 12 in the ion beam 2 is increased. As a result, space charge of the ion beam 2 can be efficiently neutralized and dispersion of the ion beam 2 due to the space charge can be effectively suppressed. Therefore, the transport efficiency of the ion beam 2 can be improved. Results of simulations of the relationship between the incident angle θ of the electrons 12, and the neutralization of the ion beam 2, i.e., suppression of dispersion will be described. FIG. 7 shows an example of dispersion of the ion beam 2 due to space charge in the case where the electrons 12 were not supplied. In the following simulations, ion species of the ion beam 2 were 31P+, the energy was 500 eV, the current was 25 μA, and the diameter D1 at the position of X=0 mm was 50 mm. When the electrons 12 were not supplied, the diameter D2 of the ion beam 2 at the position of X=350 mm is 193 mm, and it is seen that the ion beam is largely dispersed. FIG. 8 shows initial conditions of simulations of neutralizing the ion beam 2 while supplying the electrons 12. At the position of X=0 mm, ions 2b constituting the ion beam 2 were dispersedly placed in the YZ plane, and the electrons 12 were circularly placed in the periphery. The electrons 12 were emitted at various incident angles θ. At this time, the energy of the electrons 12 was 10 eV, and a ratio Ie/Ii of an electron current Ie to an ion beam current Ii was 34. FIG. 9 shows an example of the case where the incident angle θ is 89 deg. This example is similar to the arrangement of the field emission electron source disclosed in Patent Reference 1. It is seen that the electrons 12 pass through the ion beam 2 many times to reciprocally vibrate. The diameter D2 of the ion beam 2 at the position of X=350 mm is 186 mm, and it is seen that the ion beam 2 is largely dispersed and the electrons 12 hardly contribute to the neutralization of space charge of the ion beam 2. FIG. 10 shows an example of the case where the incident angle θ is 30 deg. It is seen that most of the electrons 12 are captured into orbits of the ion beam 2. The diameter D2 of the ion beam 2 at the position of X=350 mm is 116 mm, and it is seen that the electrons 12 efficiently contribute to the neutralization of space charge of the ion beam 2, and dispersion of the ion beam 2 is effectively suppressed. FIG. 11 shows an example of the case where the incident angle θ is 15 deg. It is seen that most of the electrons 12 are captured into orbits of the ion beam 2. The diameter D2 of the ion beam 2 at the position of X=350 mm is 113 mm, and it is seen that the electrons 12 more efficiently contribute to the neutralization of space charge of the ion beam 2, and dispersion of the ion beam 2 is more effectively suppressed. FIG. 12 shows an example of the case where the incident angle θ is 0 deg. The diameter D2 of the ion beam 2 at the position of X=350 mm is 111 mm, and it is seen that the electrons 12 further efficiently contribute to the neutralization of space charge of the ion beam 2, and dispersion of the ion beam 2 is further effectively suppressed. FIG. 13 shows an example of the case where the incident angle θ is −15 deg. It is seen that, even in the case where the incident angle θ is negative, when the absolute value of the angle is small as in this example, most of the electrons 12 are captured into orbits of the ion beam 2 by the positive beam potential of the ion beam 2. The diameter D2 of the ion beam 2 at the position of X=350 mm is 120 mm, and it is seen that the electrons 12 efficiently contribute to the neutralization of space charge of the ion beam 2, and dispersion of the ion beam 2 is effectively suppressed. Simulations at the incident angle θ other than the above values were performed. FIG. 14 collectively shows the diameter D2 of the ion beam 2 at the position of X=350 mm in the simulations with respect to the incident angle θ of the electrons 12. It is believed that, when the incident angle θ is made large in the negative side, dispersion of the ion beam 2 is increased because of the following reason. The electrons 12 are emitted in a direction separating from the ion beam 2, and hardly captured by the positive beam potential of the ion beam 2. As seen from the figure, preferably, the incident angle θ is in the range from −15 deg. to +45 deg., more preferably, in the range from −15 deg. to +30 deg., further preferably, in the range from substantially 0 deg. to +15 deg., and, most preferably, at substantially 0 deg. In the above simulations, the electrons 12 are emitted from the periphery of the ion beam 2. By contrast, in the embodiment of FIG. 1, the electrons 12 are emitted from the both sides of the ion beam 2, i.e., from the field emission electron sources 10 placed on the both sides of the ion beam 2. Although the conditions are slightly different as described above, the simulations and the embodiment are common in that the electrons 12 are emitted from the vicinity of the ion beam 2. From the results of the simulations, therefore, it is deduced that, also in the embodiment, results having the same tendency as the simulations are obtained by setting the incident angle θ of the electrons 12 emitted from the field emission electron sources 10 to the above-mentioned range. Namely, the field emission electron sources 10 are preferably placed in a direction along which the incident angle θ of the electrons 12 emitted therefrom is in the range from −15 deg. to +45 deg., more preferably, in the range from −15 deg. to +30 deg., further preferably, in the range from substantially 0 deg. to +15 deg., and, most preferably, at substantially 0 deg. As the incident angle θ is made smaller, dispersion of the ion beam due 2 to the space charge can be more effectively suppressed, and the transport efficiency of the ion beam 2 can be more improved. Referring again to FIG. 1, the field emission electron sources 10 may be placed in any portion of the path of the ion beam 2 extending from the ion source 1 to the holder 6. When an apparatus for applying an electric or magnetic field to the ion beam 2 exists in the ion beam 2, the electrons 12 hardly pass through the apparatus. Therefore, the electron sources 10 are preferably placed between such an apparatus and a place where dispersion of the ion beam 2 is to be suppressed, for example, on the downstream side of such an apparatus. The field emission electron source 10 may be disposed in plural places of the path of the ion beam 2 extending from the ion source 1 to the holder 6. As in the embodiment shown in FIG. 1, the field emission electron sources 10 are placed with being directed toward the downstream side, whereby the field emission electron sources 10 are placed so as to be separated from the target 4 toward the upstream side, and dispersion of the ion beam 2 can be effectively suppressed over a long distance to the target 4. The field emission electron source 10 may be placed on one side of the path of the ion beam 2. As in the embodiment shown in FIGS. 1 and 2, for example, the field emission electron source 10 may be preferably placed on the both sides of the path of the ion beam 2. According to the configuration, the electrons 12 can be supplied to the ion beam 2 from the both sides. Therefore, space charge of the ion beam 2 can be more efficiently neutralized and dispersion of the ion beam 2 due to the space charge can be more effectively suppressed. As required, the field emission electron source 10 may be placed in four places surrounding the path of the ion beam 2. This configuration is more similar to the above-described simulations. In the case where the ion beam 2 has a ribbon-like shape as in the example shown in FIG. 2, the field emission electron sources 10 preferably have an elongated shape which extends in the Y direction, i.e., the width direction of the ribbon-like shape ion beam 2. According to the configuration, even when the ion beam 2 has a shape which extends in the Y direction, space charge of the ion beam 2 can be neutralized more uniformly over a wider range of the ion beam 2. As in an embodiment shown in FIG. 6, the field emission electron sources 10 may be placed in a direction along which the electrons 12 are emitted toward the upstream side of the ion beam 2. In this case, preferably, the field emission electron sources 10 may be placed in the vicinity of the upstream side of the holder 6. The other configuration is identical with that of the above-described embodiment, and therefore duplicated description is omitted. Even when the field emission electron sources 10 are placed with being directed toward the upstream side, the electrons 12 emitted therefrom are captured by the positive beam potential Vp of the ion beam 2 while moving toward the upstream side. By the same function as that of the above-described embodiment in which the field emission electron sources 10 are placed with being directed toward the downstream side, therefore, space charge of the ion beam 2 can be efficiently neutralized and dispersion of the ion beam 2 due to the space charge can be effectively suppressed. When the field emission electron sources 10 are placed with being directed toward the upstream side, the electrons 12 emitted from the field emission electron sources 10 are hardly incident on the target 4. Therefore, it is possible to suppress negative charging of the surface of the target 4 which is produced by incidence of the electrons 12 on the target 4. This is particularly effective in the case where the energy of the electrons 12 emitted from the field emission electron sources 10 is not very low. Plural semiconductor devices may be produced on a semiconductor substrate (for example, a silicon substrate) by using the semiconductor substrate as the target 4, using the ion beam irradiating apparatus of one of the embodiments, and irradiating the semiconductor substrate with the ion beam 2. For example, the ion beam irradiating apparatus of one of the embodiments may be used in a step of implanting desired ions (for example, ions serving as impurities) into a desired region of the surface or surface layer portion of the semiconductor substrate, thereby producing plural integrated circuits (for example, system LSIs, or the like) serving as semiconductor devices on the semiconductor substrate. Recently, miniaturization of semiconductor devices formed on a semiconductor substrate is being extremely advanced (in other words, very highly integrated). When ion implantation is performed on such semiconductor devices, there is a problem of preventing formation of a portion into which ions are not implanted, or a shadowed portion, in a groove or convex portion formed in the surface of the semiconductor substrate. When the prevention is not performed, characteristics of semiconductor devices to be formed are dispersed, and a defect device may be produced. In order to solve the problem, the semiconductor substrate must be irradiated with an ion beam of high parallelism. When dispersion of the ion beam due to space charge is large, it is difficult to irradiate the semiconductor substrate with an ion beam of high parallelism. By contrast, when the ion beam irradiating apparatus of one of the embodiments is employed, plural semiconductor devices can be produced on a semiconductor substrate by using the ion beam 2 in which space charge is neutralized, and which is less dispersed. Therefore, plural semiconductor devices having uniform characteristics can be produced on the same semiconductor substrate. As a result, the yield is improved, and the production efficiency of a semiconductor device is enhanced. While the invention has been described in detail with reference to the specific embodiment, it will be obvious to those skilled in the art that various changes and modifications can be made without departing from the spirit and the scope of the invention. This application is based on Japanese Patent Application (No. 2006-162394) filed on Jun. 12, 2006, which is incorporated herein by reference.
043127070	claims	1. A nuclear fuel rod, which comprises: a cladding tube filled with an insert gas or liquid metal and sealed at both ends in airtightness; and a plurality of nuclear fuel pellets piled one atop another in the cladding tube, wherein an adsorbent carrying a tag gas for monitoring a nuclear fuel rod failure is received in the inner space of the cladding tube defined at least above or below the nuclear fuel pellet pile whereby said gas or liquid metal is released from said adsorbent when the temperature thereof increases. 2. The nuclear fuel rod according to claim 1, wherein the adsorbent is one selected from the group consisting of active carbon, Molecular Sieves, silica gel and active alumina. 3. The nuclear fuel rod according to claim 1, wherein the adsorbent is active carbon. 4. The nuclear fuel rod according to claim 1, wherein the adsorbent is received in a container. 5. The nuclear fuel rod according to claim 3, wherein the container is formed of one selected from the group consisting of stainless steel, copper and alumina and perforated at the top. 6. The nuclear fuel rod according to claim 4, wherein a disc for supporting the adsorbent container which is perforated at the center is set in the inner space of the cladding tube defined above the nuclear fuel pellet pile; and the adsorbent container is placed in a chamber provided above the support disc. 7. The nuclear fuel rod according to claim 1, wherein the tag gas is at least one of noble gas selected from the group consisting of neon, xenon, and krypton. 8. The nuclear fuel rod according to claim 3, wherein the container is formed of one selected from the group consisting of stainless steel, copper and alumina and open at the top.
045308144	claims	1. In a nuclear power plant including a steam turbine and a nuclear steam generator from which steam is discharged for driving the turbine, heat exchange apparatus having a generally cylindrical elongate shell extending horizontally between a pair of ends, inlet means for receiving the steam, outlet means for discharging the steam to the turbine, and means including at least one bundle of inclined tubes positioned in the flow path of the steam through the heat exchange apparatus and each of which has a length which is less than the shell diameter for providing a flow of vapor for transferring heat to the steam and for condensing the vapor in said tubes without sub-cooling it, each of said tubes opens into and extends in an upwardly direction from a header and lies in a vertical plane which is perpendicular to the vertical longitudinal centerplane of the shell, said header lies in said centerplane, said tube bundle comprises two banks of said tubes, and the angle at which each of the tubes of one of said banks extends relative to said centerplane is opposed to the angle at which each of the tubes of the other of said banks extends relative to said centerplane; and a fossil fuel-fired vapor generator for receiving condensate from said heat exchange apparatus, heating the condensate to generate vapor, and discharging the vapor to said tubes. 2. In a nuclear power plant according to claim 1 wherein each of said tubes has a closed upper end and has a lower end which opens into said header, and said header is connected to a source of vapor and a condensate drain. 3. A nuclear power plant according to claim 1 wherein said header is an outlet header which is connected to a condensate drain, the tubes of one of said banks terminate at and open into an inlet header, the tubes of the other of said banks terminate at and open into another inlet header, said inlet headers are connected to a source of vapor, and said inlet headers are disposed at the opposite ends of said respective tubes from said outlet header. 4. A nuclear power plant according to any one of claims 1 or 3 wherein said heat exchange apparatus is a reheater connected in the flow path of steam between a higher pressure turbine and a lower pressure turbine, and said heat exchange apparatus is positioned adjacent said turbines. 5. Apparatus according to claim 3 wherein said outlet header is suspended from said inlet headers, and the apparatus further comprises a member attached to said shell which slideably supports a member attached to each said inlet header. 6. In a power plant including a steam turbine and a steam generator from which steam is discharged for driving the turbine, apparatus for superheating the steam, the apparatus comprises a shell, inlet means in said shell for receiving the steam, outlet means in said shell for discharging the steam. a bundle of inclined tubes positioned in the flow path of the steam to provide a flow of vapor for transferring heat to the steam, each of said tubes has a closed upper end and has a lower end which opens into a header, and said header is connected to a source of vapor and a condensate drain, and the apparatus further comprises a support plate having a plurality of apertures into which at least some of said tube closed ends are inserted, and means including a plug member in at least one of said tubes and extending over a distance from said support plate in a direction toward said header of at least two inches beyond the edge of said support plate for preventing uneven heating of the support plate. 7. Apparatus according to claim 6 wherein said header includes tube sheets for insertion of end portions of said tubes, said tubes comprise fins which extend longitudinally of said tubes to said tube end portions, and said end portions are free of fins. 8. Apparatus according to claim 6 wherein the shell is generally elongate and extends horizontally between a pair of ends, said tube bundle comprises two banks of said tubes, each of said tubes lies in a vertical plane which is perpendicular to the vertical longitudinal centerplane of the shell, said header extends in a longitudinal direction of the shell and lies in said centerplane, and the angle at which each of the tubes of one of said banks extends relative to said centerplane is opposed to the angle at which each of the tubes of the other of said banks extends relative to said centerplane. 9. Apparatus according to claim 6 wherein at least one of said tube closed ends is free of anchoring to said support plate to thereby allow for expansions and contractions. 10. Apparatus according to any one of claims 1 or 6 further comprising a diffuser separator at said steam inlet means. 11. Apparatus according to claim 10 further comprising secondary separators disposed in the flow path of the steam between said diffuser separator and said bundle of tubes. 12. Apparatus according to claims 1, 6, or 7 wherein said two banks of tubes extend from said header in generally the configuration of a "V" as viewed in a cross-section of the apparatus taken in a plane perpendicular to the longitudinal axis of the apparatus, and the angle which each of said tubes forms with the vertical longitudinal centerplane of said shell is between about 30 and 60 degrees. 13. Apparatus according to any one of claims 6, 7, or 8 wherein each of said tubes has a length which is less than the diameter of said shell.
048329029	description	DETAILED DESCRIPTION OF THE EMBODIMENT The apparatus 50 (FIGS. 1,2) for refueling a nuclear reactor shown in the drawings serves to engage selected component assemblies of a nuclear reactor 51 (FIG. 3), raise these components, transport them and lower them into a selected position. The general operation of this apparatus 50 and the purposes which it serves is disclosed in Swidwa. The reactor 51 is disposed in a pit under water 53, (FIG. 2) 20 or 30 feet in depth in a containment defined by massive walls 55. The apparatus 50 includes a bridge 57, a trolley 59 and a mast assembly 61 (FIGS. 1, 2, 3, 3C, 3D, 16, 27A). The bridge is moveable on rails or tracks 62 and 63 (FIGS. 1, 7, 8, 9, 12). These tracks are similar except that track 63 has a position verification cam 64 (FIGS. 7, 8,9). The tracks 62 and 63 are supported on base plates 74 in slots on the tops of opposite walls 55 (FIG. 8). Normally the slots are filled with grout (not shown). As shown for track 63 in FIGS. 7 and 8, each track is held down by rail clips 66 which engages a flange 72 along one side. Lateral movement is suppressed by a keeper 68 (FIG. 8) along the opposite side. Indicator strip 70 extend along one side of track 63. The indications from the strips 70 are picked up by a television camera (not shown) on the bridge. The bridge 57 includes trucks 65 and 67 (FIGS. 2, 3A, 9). Each truck has a driven wheel 69 and an idler wheel 71 on shafts extending between back-to-back channels 73 and 75. I-beams 77 and 79 interconnect the trucks 65 and 67. I-beam 77 is adjacent the driven wheels 69. The channels 73 and 75 extend through cut-outs 102 in each beam 77 and 79. Plates 104 welded to the webs of the I-beam are bolted to the upper flanges of the channel. FIG. 3A shows this structure for I-beam 77 which is adjacent the driven wheels 69. The wheels 69 are driven by motor 100 through speed reducer 106 (FIG. 3B). The motor 100 and speed reducer 106 are mounted on a bracket 108 welded to the web of I-beam 77 and supported on small I-beams 110 welded to I-beam 77. The motor 100 drives shaft 81 (FIGS. 1, 3B) whose sections are connected through couplings 83 and 85 to pinions 110A. Each pinion engages a gear 112 (FIG. 1) on driven wheel 69. Wheels 69 are rotatable on sleeve bearings (not shown) on their shafts. Wheels 71 are secured to their shafts 98. The shafts 98 are rotatable on bearing cartridges 80 (FIGS. 4, 12) which are journaled in the channels 73 and 75. One idler wheel 71 drives a pulse generator or pulser 76 (FIG. 4) which produces pulses that measure the movement of the bridge 57 from a reference position. A pulley wheel 78 is keyed to the shaft 98 with which one of the wheels 71 is rotatable on bearing 80. Pulley wheel 78 drives a second pulley wheel 82 of very much smaller diameter than pulley 78 through a timing belt 84. The pulser 76 produces pulses at a far higher rate than the rate of rotation of the wheel 71. The position of mast assembly 61 along tracks 63 and 65 is measured by the number of pulses produced by the pulser 76 as the mast assembly moves from the reference position to the position in question. A verification limit switch 86 is supported on a bracket 88 suspended from channel 75 (FIGS. 8, 9). The limit switch 86 is actuable by the position verification cam 64 when the bridge 57 passes over the cam. Initially the apparatus is calibrated so that the position of the cam 64 corresponds to the number of pulses produced by pulser 76 as the bridge moves from the reference position to the position of the cam. A control console 90 (FIG. 2) is mounted on the trolley deck 92. The console includes a computer 94 (FIG. 17) with a memory. The pulser 76 is connected to the computer through conductor 96 (FIGS. 4, 17). The count of the train of pulses from the reference position to any position of the bridge 57 is entered in the computer. Through line 150 from motor 100 (FIG. 17), the computer receives intelligence of the direction of movement of the bridge and it is programmed to add to the number of pulses if the direction is forward from the reference position and to subtract from the number of pulses if the direction is backward. The intelligence of actuation of limit switch 86 is also entered in the computer 94 through conductor 102A (FIGS. 9, 17). The calibrated count corresponding to the actuation of switch 86 is also entered in the computer. The computer is programmed to correct the calibration if the actual count deviates from the calibrated count. A frame-like super structure 87 (FIG. 2) is bolted to the trucks 65 and 67 of the bridge spanning the trucks. The super structure 87 has an overhang 89 (FIG. 2) at the top which carries a hoist 91 for tools. The hoist 91 may be moved between the opposite walls 55 of the pit by a chain 93 (FIG. 3). The hoist be operated by a pushbutton switch 95 suspended from the hoist. Power is supplied to the hoist 91 by power track 95A (FIG. 1). Some of the tools which are used with hoist 91 are operated by compressed air. The bridge 57 is provided with a walkway 97 (FIG. 1) on one side. A safety fence 99 to protect personnel from the trolley wheels extends along the walkway on the side of the pit. Handrails 101 extending frome the trolley permit personnel to step safely from the trolley 59 to the walkway. While the fluid for driving the fluid operable means may be of any type, the fluid typically used in the practice of this invention is compressed air. An assembly including a compressor 103 and a tank 112A and associated switch means and relief valves (FIG. 2, see also (FIG. 17)) is mounted on truck 65 of the bridge 57 to supply the compressed air. Air may be selectively supplied to the tools on hoist 91 through air hose 107 and by air hose 109 (FIG. 5A) to the trolley 59 for the air-operated devices on the mast 61. The apparatus 50 is supplied with power from a power outlet (not shown) on the containment through a conductor 111 (FIG. 4). Between the outlet and the bridge 57 the power line includes a plurality of festoon loops (not shown). The trolley 59 is moveable on tracks or rails 121 and 123 (FIG. 3D) on I-beams 77 and 79. Like the bridge 57 the trolley 59 is moveable along tracks 121 and 123 on trucks 125 and 127 (FIG. 3D). Each truck has a driving wheel 129 (FIG. 3D) and an idling wheel 131 (FIGS. 10, 11). Each pair of wheels is suspended from back-to-back channels 133 and 135. Each driven wheels 129 is rotatable on sleeve bushings on a shaft supported between a pair of channels 133 or 135, 133 on the outside and 135 on the inside. The channel units 133-135 are strengthened by gussets 162 (FIG. 2). The supporting structures of the trolley 59 is a frame 114 formed of additional channels 116, I-beams 118 and plates 120 (FIG. 3C) welded to the channels 133 or 135 of the trucks 125 and 127. A long plate or platform 122 (FIG. 3D) is welded to the lower ends of the channels 133, 135, and 116 along the side 162A of the trolley 59 where the driving wheels 129 are suspended. This plate 122 carries the drive for the wheels 129 including a transformer 124, a motor 126 and speed reducer 128. The drive shaft 130 formed of sections connected by couplers 134 extends from the speed reducer 128. At its ends the drive shaft 130 is connected to pinions 136 which drive gears 138 connected to the wheels 129. The motor 126 is controlled from the computer 94 (FIG. 17) and feeds back its direction of rotation to the computer through line 164. At the top the frame 114 is covered by doors 142 (FIGS. 3C, 3D) and plates 144 which form the deck 92. The deck is provided with a grating 146 through which the pit under the trolley 59 may be viewed. The deck also has pads 148 (FIG. 3C) for supporting the mast assembly 61. Doors 170 are interposed between the pads 148. There are also supports 152 for the control console 90. There is an electrical junction box 154 (FIG. 24) under the trolley which is accessible through a hole in the deck 92 by removing grating 146. Each idling wheel 131 is rotatable with a shaft 137 on bearing cartridges 139 supported by a channel 133 or 135. A toothed pulley wheel 141 (FIG. 5) is keyed to the shaft 137 of one of the idling wheels 131. This pulley wheel 141 drives a pulse generator or pulser 143 through a pulley wheel 145 of much smaller diameter through a timing belt 147. The pulser 143 is connected to computer 94 through conductor 151 (FIG. 17). A verification cam 153 (FIG. 10) is mounted at a predetermined position along track 123. A verification limit switch 155 is mounted on a bracket 157 suspended from the channel section 133. The limit switch 155 is positioned to be actuable by the cam 153 when the trolley passes over the position of the cam. The actuation of the limit switch 155 is entered in computer 94 (FIG. 17) through line 159. The cooperation of the pulser 143, the limit switch 155 and the computer 94 is similar to the cooperation in the case of the like components of the bridge 57. The number of pulses in a pulse train produced by pulser 143 as the trolley moves from a reference position to a given position along the tracks 121 and 123 measures the displacement of the given position from the reference position. The counts of pulses by the computer 94 is positive when the trolley 59 moves forward, away from the reference position, and negative when the trolley moves backward, towards the reference position. There is a one-to-one relationship between the count of positive pulses and each position of the trolley 59. The apparatus is calibrated so that the position of cam 153 on track 123 corresponds to a predetermined number of pulses which are entered in computer 94. If the calibration is impaired, there is a deviation between the number of pulses counted by the computer between the reference position and actuation of switch 155 and the entered calibration count. The computer is programmed to make a correction. A handrail 171 (FIGS. 1 and 2) extends around the trolley deck 92. Adjacent the track 121 along the I-beam 77 there is an indicator strip 173 (FIG. 1, 13). This strip carries indications of positions along the pit in the direction of track 121. The indications on strip 173 are picked up by a television camera 175 (FIG. 13) suspended from a bracket 177A secured to the trolley 59. By viewing the screen of the viewer tube (not shown) on the control console 90, which is connected to camera 175, the operator can determine at first hand the approximate position of the trolley along the pit. A cable tray 177 (FIGS. 5A) is connected at one end to a plate 179 suspended from I-beam 77 and at the other end to the underside of trolley 59 (deck 92). The slot of the cable tray 177, which carries the cables is horizontal. The cable tray carries the compressed-air hose 109, the power conductor 111, (FIG. 4), the conductor 102A from the verification switch 86 (FIG. 9) on the bridge 57, the conductor 96 from the pulser 76 (FIG. 4) on the non-driven wheel 71, and the conductor 175A from the 175 television camera. The cable tray 177 permits the bridge 57 and trolley 59 to travel relative to each other without disturbing the cables on the trolley side. Except for the compressed-air hose 109, the conductors on cable tray 177 are connected to the junction box 154 (FIG. 24) under the trolley and thence are connected to the console 90. The hose 109 is connected to the hose 181 on the mast assembly 61 through pressure regulator 183 (FIGS. 21). Conductors powered by line 111 also are connected from the junction box 154 to facilities on the mast assembly. The mast assembly 61 is described in Swidwa. For any information in addition to that presented here that may be of interest, reference is made to Swidwa. The mast assembly 61 includes a supporting mast 201 (FIGS. 2, 3, 16, 22) of circular, transverse cross-section. The supporting mast 201 has windows 203 (FIGS. 2, 3, 16) through which the operation of the parts within the mast 201 may be observed. The supporting mast 201 is secured to ring 205 (FIG. 16) from which a long guiding mast 207 of circular transverse extends. The apparatus also includes an auxiliary mast or bearing mast 20 (FIGS. 2, 3, 16, 22). Brackets 211 extend from the auxiliary mast 209 near its lower end. These brackets engage the bracket pads 148 (FIG. 3C) on the deck 92 of the trolley 59. The auxiliary mast 209 has a flange 213 (FIGS. 14, 15, 16) at the top which carries a thrust-bearing ring 215. The ring 205 has a seat for the bearings 215, supporting mast 201 and the ring 205 and guiding mast 207 and other parts supported from the supporting mast are rotatable on the bearings 215. The supporting mast 201 has a rectangular flange 217 at the top. There are supported directly on this flange 217 a platform 218 (FIGS. 2, 16), on which a winch 219 (FIGS. 2, 16) is mounted, and an electric conductor reel 221 (FIG. 23) and an air-hose reel 222 (FIGS. 16, 21). An additional reel 223 for electric conductors and an additional air-hose reel 225 is supported from a platform 227 mounted on legs 229 on flange 217 (FIGS. 16, 23). An elongated member 231 (FIG. 35) having at its lower end, grapples (not shown) for engaging a control-rod cluster (not shown) or a thimble-plug cluster (not shown) of the reactor 51 to be refueled, are moveable upwardly or downwardly by the winch 219. The elongated member 231 includes a tube 233 (FIG. 16) to the upper end of which a plate 237 is secured. The plate 237 is formed into a rigid mechanical unit with an upper-plate assembly 239 by four support rods 241. The rods 241 engage plate 237, and are secured by nuts to the plate 243 of the upper-plate assembly. The flange 245 (FIG. 16) of a yoke 247 engages the plate 243 and carries a cylinder 249, typically an air cylinder. The flange 245, plate 243 and cylinder 249 are connected together as a rigid unit. The piston rod 251 of cylinder 249 actuates a rod 253 to move upwardly or downwardly in the tube 233. When actuated to its utmost down position, the rod 253 causes the grapple (not shown) to engage the control rod assembly or thimble-plug assembly which is to be raised. In the up position of the rod 253, the grapple may be disengaged from the component assembly. Limit switches 254 and 256 (FIG. 18) are provided for signaling that the piston rod 251 is at its extreme positions. The yoke 247 is pivotally connected to the lower junctions of swivels 255. The upper junction of each swivel 255 is pivotally connected to a clevis 257. Each clevis 257 is suspended from a threaded member 259 at the end of a cable 261 from the winch 219. The winch 219 is provided with a pulse generator 263 (FIG. 6) which is actuable by a toothed member (not shown) driven by the winch motor 265 (FIGS. 1, 2) synchronously with the winch. The pulser 263 operates analogously to the pulsers 76 (FIG. 4) and 143 (FIG. 5) to produce trains of pulses whose number measures the height of the elongated member 231 (FIG. 16). The numbers of pulses are entered in the computer 94 through line 267 (FIGS. 6, 17). The winch motor 265 is controlled from the computer 94 and enters its direction of rotation in the computer through line 269. The numbers of pulses are entered in a positive sense when the elongated member 231 moves downwardly and in a negative sense when the mast moves upwardly so that there is a one-to-one relationship between the position of the member 231 and the net number of pulses entered in the computer 94. The apparatus may be calibrated so that the position of the elongated member for each number of pulses is known. A calibrated verification limit switch 271 is suspended from a bracket 272 of the supporting mast 201, (FIGS. 16, 16A). The switch 271 is actuable by a bar 273 on the switch which is in turn actuated by the plate 243 of the upper plate assembly 239 when the bar 273 is at the level of switch 271. The actuation of switch 271 is entered in the computer 94 through line 275 (FIG. 17). The computer is programmed to check if the indicated position of the limit switch 271 corresponds to the calibration of the elongated member position and to correct the calibration if there is a deviation. The mast assembly also includes an inner mast or gripper mast 281 (FIG. 16). This mast 281 is of generally rectangular cross section composed of oppositely disposed channels formed into a rigid unit by cross snow-flake plates (FIG. 34), as shown in detail in Swidwa. The inner mast carries a gripper 285 (FIG. 3) for engaging a fuel assembly (not shown). The supporting mast 201 may be locked in an initial position by a locking screw 311 (FIGS. 14, 15) operated by knob 313. The screw 311 and knob 313 are suspended from bracket 315 secured to the mast 201. When the knob 313 is turned the screw tip 317 penetrates into a hole in the flange 213 of the auxiliary mast 209. In the initial position of the supporting mast 201, the plunger 318 of a limit switch 319, supported from a bracket 321 in mast 201, is held in a predetermined setting by a cam 323 in the flange 213. When the mast 201 is rotated, this switch 319 is actuated. The disposition of electrical conductors on the mast assembly 61 in the practice of this invention will now be discussed with reference to FIG. 19. The heavy black lines in FIG. 19 each represents a cable or harness including a number of wires. The following cables are connected to parts which are moveable up or down with the elongated member 231 or the inner mast 281: The cable 331 from the television camera 286 which serves for observation of the gripper assembly; PA1 The cable 333 from the light source 288 associated with camera 288; PA1 The cable 335 from the limit switch 301 which signals one setting gripper cylinder 299; PA1 The cable 337 from the limit switch 303 which signals the opposite setting of cylinder 299; PA1 The cable 339 from the limit switch 293 which signals one setting of cylinder 291 for the yoke; PA1 The winch motor 265 (FIGS. 1, 2); PA1 The pressure switches 375 (FIG. 18) on the compressed air line 109; PA1 Limit switch 319 (FIGS. 14, 15) signalling displacement of supporting mast 201 from its initial position. The cable 341 from the limit switch 295, which signals the opposite setting of cylinder 291. These cables 331 through 341 are connected to the input terminals of junction box 343 (FIGS. 19) which is mounted on the plate 287 of the inner mast 281. The output cable or harness 345 from box 343, which includes conductors carrying the current of all input conductors is wound on cable reel 223 (FIGS. 1, 2, 3, 16, 21, 22). The conductors are connected through a slip ring system 344 (FIG. 1) to cable section 346 (FIG. 19). Cable section 346 passes through an additional cable tray 347 (FIGS. 1, 21, 22, 23) to junction box 349. Cable section 351 from the junction box 349 passes through wire way 353 to the junction box 154 (FIG. 32) under the deck 92 of the trolley 59. Cable section 355 from this junction box 154 is connected to a rack 357 (FIG. 19) in the control console 90. Television cameras 359 and 361 are mounted on guiding mast 209. Since this mast is not moveable, cables 363 and 365 for these cameras are connected directly, and not through a reel, to a rack 367 of console 90 through cable tray 347, junction box 349, wire way 353 and intermediate cable sections. The cable from limit switches 254 and 256 (FIG. 18) for the cylinder 249 which controls the movement of the elongated mast 231 is wound on reel 221 (FIG. 23). The cable from the slip ring (not shown) of this reel 221 and the conductors from the following components are passed through a Y wireway 371, (FIG. 27B) whence they pass through cable tray 347 in conduits 377 (FIGS. 22, 23). The solenoids (not shown) for the valves which control the flow of compressed air to the cylinders 249, 291, 299 (FIG. 18). The pulser 263 (FIG. 6) measuring the height of the elongated member 231. The limit switch 271 (FIGS. 16, 16A) which verifies the calibration of the height of the elongated member: These conductors are combined in conduits 377 (FIGS. 22, 23) connected to the Y wire way 371. The conduits pass through the cable tray 347 (FIG. 22) to the junction box (FIG. 22) where they are connected to conductors which pass through wire way 353 and to junction box (not shown) under deck 92. At this junction box 154 the conductors are appropriately connected to the console 90. The conductors from the pulsers 76 (FIG. 4) on the bridge 57 and 143 (FIG. 5) on the trolley 59 are connected directly to the junction box 154 and thence to the control console 90. The verification limit switches 86 (FIG. 9) operated by the bridge and 155 (FIG. 10) operated by the trolley are likewise connected to the control console through junction box 154. The compressed air is distributed to the cylinders 249, 291, 299 through a manifold 381 (FIGS. 18, 25, 31). The hose 181 is connected to the input 383 of the manifold. The outputs of the manifold are delivered through valves 385 (FIGS. 18, 31), each of which is actuable by a solenoid 373. The valves 385 remain in the last position to which they are actuated. If solenoid A (FIG. 18) is last actuated, the flow is as shown in FIG. 18 into the upper terminal of a cylinder and out at the lower terminal as represented by arrows 387 and 389. If solenoid B is last actuated, the flow is into the lower terminal and out of the upper terminal as represented by the arrows 391 and 393. Four of the output hoses 395 (FIG. 31) are connected to inputs 397 of the upper hose reel 225. Two of the output hoses 398 are connected to the inputs 399 (FIG. 23) of the lower reel 222. The hoses 401 extending from the peripheral output of reel 225 supply compressed air selectively to the cylinder 299 for operating the grippers and to the cylinder 291 for operating the yoke 289 on the inner mast 281 (FIGS. 16, 18). The two peripheral hoses 403 from reel 222 supply compressed air selectively to operate the cylinder 249 for moving the rod 253 in tube 233 (FIGS. 16, 23). While a preferred embodiment of this invention has been disclosed herein, many modifications thereof are feasible. This invention is not to be limited except insofar as is necessitiated by the spirit of the prior art.
	claims	1. A hybrid reactor operable to produce a medical isotope, the reactor comprising:an ion source operable to produce an ion beam from a gas;a target chamber including a target that interacts with the ion beam to produce neutrons via a fusion reaction, wherein the target comprises deuterium, tritium, or helium, or a combination thereof; andan annular activation cell positioned proximate the target chamber and including a parent material that interacts with the neutrons to produce the medical isotope via a fission reaction, wherein the parent material is in an aqueous solution, wherein the water of the aqueous solution acts as a moderator, and wherein the fission reaction is maintained at a subcritical level with neutron multiplication. 2. The hybrid reactor of claim 1, wherein RF resonance is used to produce the ion beam. 3. The hybrid reactor of claim 1, further comprising an accelerator positioned between the ion source and the target chamber and operable to accelerate the ions of the ion beam. 4. The hybrid reactor of claim 1, wherein the gas includes one of deuterium and tritium and the target includes the other of deuterium and tritium. 5. The hybrid reactor of claim 1, wherein the target chamber defines a long target path that is substantially linear. 6. The hybrid reactor of claim 5, further comprising at least one magnet positioned to define a magnetic field that collimates the ion beam within at least a portion of the long target path. 7. The hybrid reactor of claim 1, wherein the target chamber defines a long target path that is substantially helical. 8. The hybrid reactor of claim 7, further comprising at least one magnet positioned to define a magnetic field that directs the ion beam along the helical path. 9. The hybrid reactor of claim 1, wherein the ion source and the target chamber together at least partially define one of a plurality of fusion reactors. 10. The hybrid reactor of claim 9, wherein the target chamber of each of the plurality of fusion reactors cooperate to substantially surround a cylindrical space. 11. The hybrid reactor of claim 10, wherein the activation cell is substantially annular and is positioned within the cylindrical space. 12. The hybrid reactor of claim 1, further comprising a reflector positioned proximate the target chamber and selected to reflect neutrons toward the activation cell. 13. The hybrid reactor of claim 1, wherein the parent material comprises uranium enriched to 20% or less of 235U and the medical isotope is 99Mo. 14. The hybrid reactor of claim 1, further comprising an attenuator positioned proximate the activation cell and selected to maintain the fission reaction at a subcritical level. 15. The hybrid reactor of claim 12, wherein the attenuator is positioned inside of the annular activation cell and the reflector substantially surrounds the plurality of target chambers. 16. A hybrid reactor operable to produce a medical isotope, the reactor comprising:an ion source operable to produce an ion beam from a gas;a target chamber including a target that interacts with the ion beam to produce neutrons via a fusion reaction, wherein the target comprises deuterium, tritium, or helium, or a combination thereof; andan annular activation cell positioned proximate the target chamber and including an aqueous solution comprising a parent material that interacts with the neutrons to produce the medical isotope via a fission reaction, wherein the water of the aqueous solution acts as a moderator, and wherein the fission reaction is maintained at a subcritical level with neutron multiplication. 17. The hybrid reactor of claim 1, further comprising an additional moderator substantially surrounding the activation cell.
	description	The present invention will be described in detail in conjunction with what is presently considered as preferred or typical embodiments thereof by reference to the drawings. In the following description, like reference characters designate like or corresponding parts throughout the several views. Further, as is apparent from the description described below, the present invention is not limited to those embodiments but various modifications and equivalents can be resorted to. FIG. 1 shows a control rod according to a first embodiment of the present invention. At this juncture, it should be mentioned that the structure of the control rod cluster itself which is constituted by the control rods according to the invention as well as that of the fuel assembly into or from which the control rod cluster is inserted/withdrawn may be same as those known heretofore. Accordingly, for the detail of these structures, reference may have to be made to FIGS. 3 to 5 as occasion requires. Referring to FIG. 1, the control rod according to the first embodiment of the invention includes a cladding tube 11 formed of stainless steel and hermetically closed at both sides thereof by a top end plug 12 and a bottom end plug 13. Accommodated within the cladding tube 11 is a rod-like neutron absorber 14 according to the instant embodiment of the invention. The neutron absorber 14 is formed of a neutron absorbing material such as an Agxe2x80x94Inxe2x80x94Cd (silver-indium-cadmium) alloy or boron carbide or the like and pushed or pressed downwardly onto the bottom plug 13 at a bottom end surface by means of a hold-down spring 15 which is disposed on atop end face within the cladding tube 11. Further, the neutron absorber 14 includes a reduced-diameter portion 14a located on the side to the bottom end plug and an ordinary diameter portion 14b located above the reduced-diameter portion, wherein a sleeve 16 is disposed within an annular space defined between an outer peripheral surface of the reduced-diameter portion 14a and an inner peripheral surface of the cladding tube 11. The sleeve 16 may be formed of a same material as that of the cladding tube 11 or a material with a thermal expansion coefficient (or rate of thermal expansion) smaller than that of the cladding tube 11 and which has strength that is high enough to withstand a force which may be applied to the sleeve 16 due to expansion of the reduced-diameter portion 14a in the radial direction. Dimensional relations among the sleeve 16, the neutron absorber 14 and the reduced-diameter portion 14a are selectively determined to satisfy the conditions that LA greater than LB and that dA less than dB, where LA represents the axial length (length in the axial direction) of the sleeve 16, LB represents the axial length of the reduced-diameter portion 14a, dA represents the outer diameter of the reduced-diameter portion 14a, and dB represents the outer diameter of the other ordinary portion 14b of the neutron absorber 14. Parenthetically, the axial length LB of the reduced-diameter portion 14a may be selected to be equal to the axial length L of the reduced-diameter portion 54a of the conventional neutron absorber heretofore so long as the control rod according to the instant embodiment of the invention is of same type as the conventional one. As mentioned above, the sleeve 16 may be formed of a same material as that of the cladding tube 11 or a material having a smaller thermal expansion coefficient than the cladding tube 11. In this conjunction, it is preferred to select the material for forming the cladding tube 11 from of austenite type stainless steel (e.g. SUS 304, SUS 316, SUS 347, SUS 348 and so forth which are employed for forming the cladding tube) and anti-corrosion/heat-resistant nickel-based alloys such as Inconel 718 (registered trade name) and the like. Unless the sleeve 16 is formed of the same material as that of the cladding tube 11, material for the sleeve 16 should be so selected that the conditions mentioned below can be satisfied. 1) In respect to the thermal expansion, the sleeve 16 should not be brought into contact with the inner peripheral surface of the cladding tube 11 nor exert internal pressure load to the cladding tube 11 due to excessively large thermal expansion of the sleeve 16 in the high temperature operating state. 2) With regard to the yield strength, the sleeve should have a strength equivalent to or greater than that of the cladding tube 11 so as to be capable of withstanding a load of radial direction (internal pressure) as applied. Additionally, in respect to the load applied in the axial direction, the sleeve should exhibit a buckling strength which can withstand the load applied upon stepwise driving of the control rod cluster. 3) Concerning the thermal conduction, the material for the sleeve should have a thermal conductivity which allows the temperature of a center portion of the neutron absorber to remain lower than the melting point of the neutron absorber even with the temperature rise due to xcex3-induced heat generation in the reduced-diameter portion 14a of the absorber upon irradiation. Parenthetically, in the case of a low melting point Agxe2x80x94Inxe2x80x94Cd (silver-indium-cadmium) alloy, the temperature of the center portion of the neutron absorber should not exceed ca. 800xc2x0 C.). 4) Concerning the crack yield strength, the cracking strain of the sleeve after the irradiation should be equivalent to or more than the cladding tube 11. With the phrase xe2x80x9ccrack strainxe2x80x9d, it is intended to mean such a strain at which initiation of fracture can be observed in a cylindrical vessel subjected to an internal pressure. In practice, crack strain is conventionally used on the basis of experimentally obtained knowledges for indicating a strain of magnitude smaller than the fracture strain (elongation) and the uniform strain in conventional tensile tests. Concerning the dimensions of the sleeve 16, the diameter (thickness) thereof is determined in combination with the selection of the material for satisfying the condition imposed in respect to the strength as mentioned in paragraph 2 above. In this conjunction, the sleeve is so designed as to meet the conditions mentioned below. 1) In respect to the temperature at a center portion of the neutron absorber 14, the sleeve is so designed that this temperature can remain lower than the melting point of the absorber through thermal conduction even with the heat generation in the reduced-diameter portion 14a, the sleeve 16 and the cladding tube 11 due to the xcex3-radiation. By way of example, in the case of the Agxe2x80x94Inxe2x80x94Cd alloy which has a relatively low melting point, the temperature at the center portion of the absorber must not exceed ca. 8OOxe2x80x2C. 2) In view of realization of an extended service life of the cladding tube in the wholesome state, the time taken for the internal pressure applied to the cladding tube 11 to make appearance after the start of the irradiation is at least longer than the corresponding time in the conventional control rods. More specifically, so long as the sum of clearance between the outer diameter of the reduced-diameter portion 14a and the inner diameter of the sleeve 16 and clearance between the outer diameter of the sleeve 16 and the inner diameter of the cladding tube 11 is same as the clearance between the outer diameter of the reduced-diameter portion 54a and the inner diameter of the cladding tube 51 in the conventional cladding tube shown in FIG. 6, it is expected that the service life of the control rod can be extended for a time period which corresponds to the time taken for the reduced-diameter portion 54a to expand in the axial direction under the irradiation. Thus, in the control rod according to the instant embodiment of the invention, the outer diameter dA of the reduced-diameter portion 14a of the neutron absorber is further reduced when compared with the diameter d, of the reduced-diameter portion 54a of the neutron absorber 54 in the conventional control rod on the condition that the neutron absorbing capability can be sustained within a tolerance range, while the thickness of the sleeve 16 is increased by an amount corresponding to the difference between the diameters dA and (d1 mentioned above (i.e., d1xe2x88x92dA). 3) The clearance between the outer diameter of the reduced-diameter portion 14a and the inner diameter of the sleeve 16 as well as the clearance between the outer diameter of the sleeve 16 and the inner diameter of the cladding tube 11 can be set to appropriate values, respectively, which may be determined by taking into consideration the assemblability and manufacturability of the control rod. In that case, these clearances should be so determined that smooth insertion can be ensured without incurring interference even when tolerances imposed on the above-mentioned outer diameters and inner diameters in combination are most severe. In practical applications, the clearances may be set to values obtained by adding ca. 0.05 mm to the differences between the aforementioned outer diameters and the inner diameters, respectively, for the most severe tolerances while taking into account bend of the sleeve 16. Accordingly, when the control rod according to the present invention and a conventional one are of the same size, at least the condition that dB=d0 (see FIGS. 1 and 6) holds true. However, because the diameter of the reduced-diameter portion 14a of the neutron absorber in the control rod according to the invention is further reduced down to the limit at which the neutron absorbing capability can be sustained, the relation between the diameter dA of the reduced-diameter portion 14a of the neutron absorber in the control rod according to the invention and the corresponding diameter d1 of the reduced-diameter portion in the conventional control rod can naturally be represented by dA less than d1 (see FIGS. 1 and 6). Thus, the diameter reduction of the neutron absorber in the control rod according to the invention should preferably exceed the diameter reduction of the neutron absorber in the conventional control rod by a value falling within a range of about 0 to 0.7 mm. Furthermore, the axial length LA of the sleeve 16 should preferably be so selected as to be substantially equal to the axial height of the reduced-diameter portion 54a of the conventional control rod, while the axial length LB of the reduced-diameter portion 14a of the neutron absorber may be selected to a value obtained by subtracting height of a tapered portion (ca. 20 mm) from the axial length LA of the sleeve 16. Further, in the control rod according to the instant embodiment of the invention, the axial length of the bottom end plug 13 is lengthened by xcex94L when compared with that of the conventional control rod having the same overall length as the control rod according to the instant embodiment of the invention. However, because the axial length of the top end plug is shortened by xcex94L in the control rod according to the instant embodiment of the invention, the axial lengths of the cladding tube 11 and the neutron absorber 14, respectively, of the control rod according to the invention are substantially the same as those of the conventional control rod. When the axial length of the bottom end plug is increased by xcex94L, as described above, the relative positional relation between the neutron absorber and the fuel will naturally deviate in the state where the control rod is fully inserted into the guide tube of the fuel assembly, as a result of which in the region where neutrons are emitted from the fuel, the region where the neutrons cannot be covered by the neutron absorber (a region in the vicinity of the bottom end of the fuel rod) will increase. In this conjunction, increase of the region incapable of neutrons up to ca. 15 mm at maximum is considered to be permissible from the nuclear standpoint. Accordingly, the upper limit of the increase xcex94L in the axial length of the bottom end plug 13 should be ca. 15 mm. As is apparent from the foregoing, in the control rod according to the first embodiment of the invention, the sleeve 16 disposed within the annular space defined between the outer peripheral surface of the reduced-diameter portion 14a and the inner peripheral surface of the cladding tube 11 has a sufficient strength against the expansion of the reduced-diameter portion 14a in the radial direction. Thus, the tendency of the reduced-diameter portion 14a to expand in the radial direction can be suppressed by the sleeve 16. In this way, not only the expansion of the neutron absorber 14 in the radial direction under irradiation with neutrons but also radial expansion thereof due to shock applied upon stepwise driving of the control rod cluster can be effectively suppressed, whereby the integrity of the cladding tube 11 can be maintained over an extended period. Furthermore, because the sleeve 16 is formed of the same material as the cladding tube 11 or a metal material having a lower thermal expansion coefficient than the cladding tube 11, the integrity of the cladding tube 11 can be protected against damage due to thermal expansion of the sleeve 16. In addition, because the lower peripheral edge of the ordinary diameter portion 14b, exclusive of the reduced-diameter portion 14a of the neutron absorber 14, is chamfered with the top end portion of the sleeve 16 being also chamfered complementarily, the axial length LA of the sleeve 16 is slightly increased beyond the axial length LB of the reduced-diameter portion 14a, so the ordinary diameter portion 14b of the neutron absorber 14 above the reduced-diameter portion 14a thereof can be placed in a state supported from the underside. Thus, it is difficult for the shock applied upon stepwise driving of the control rod cluster to be transmitted to the reduced-diameter portion 14a, whereby the tendency of the reduced-diameter portion 14a to expand radially can be more positively suppressed. Besides, by increasing the length of the bottom end plug 13 by xcex94L, possible interference of the control rod with the control rod guide tube 34 is limited to the bottom end plug 13 of the control rod. Thus, the cladding tube 11 can be protected against abrasion due to such interference. The control rod according to a second embodiment of the present invention will be described by reference to FIG. 2. As can be seen in the figure, the control rods according to the second embodiment are implemented in such a structure that a cladding tube 11 formed of a stainless steel is hermetically closed at both ends by a top plug 12 and a bottom plug 13, respectively, wherein a rod-like neutron absorber is accommodated within the cladding tube 11. The neutron absorber 14 is formed of a neutron absorbing material such as an Agxe2x80x94Inxe2x80x94Cd (silver-indium-cadmium) alloy or boron carbide or the like and pressed downwardly against a bottom plug 13 by means of a hold-down spring 15 disposed within the cladding tube 11 at a top end portion thereof. Further, the neutron absorber 14 includes a reduced-diameter portion 14a which is located at the side of the bottom end plug and which has a smaller diameter than the other portion of the neutron absorber 14 having an ordinary diameter, wherein a sleeve 16 is disposed within an annular space defined between the outer peripheral surface of the reduced-diameter portion 14a and the inner peripheral surface of the cladding tube 11. The sleeve 16 is formed of the same material as that of the cladding tube 11 or a material of a smaller thermal expansion coefficient (or rate of thermal expansion) than the cladding tube 11 and has a sufficient strength for withstanding expansion of the reduced-diameter portion 14a in the radial direction. Further, the sleeve 16 has a cover head 17 at a top end thereof, and the neutron absorber 14 is divided into the reduced diameter portion 14a and the other portion 14b of the ordinary diameter by the cover head 17. In the control rod according to the second embodiment of the invention, the sleeve 16 disposed within the annular space defined between the outer peripheral surface of the reduced-diameter portion 14a of the neutron absorber 14 and the inner peripheral surface of the cladding tube 11 has sufficient strength to withstand the expansion of the reduced-diameter portion 14a of the neutron absorber 14 in the radial direction. Thus, there can be obtained advantageous effects similar to those of the control rod according to the first embodiment of the invention described hereinbefore. Besides, owing to the structure in which the neutron absorber 14 is separated into the reduced-diameter portion 14a and the portion 14b of the ordinary diameter by the cover head 17 of the sleeve 16, it is difficult for shock generated when the control rod cluster is driven stepwisely to be transmitted to the reduced-diameter portion 14a of the neutron absorber 14. As a result, expansion of the reduced-diameter portion 14a of the neutron absorber 14 in the radial direction can be suppressed more positively. As will now be understood from the foregoing description, according to the teachings of the present invention, expansion of the reduced-diameter portion of the neutron absorber in the radial direction can be suppressed notwithstanding the shocks applied during each stepwise driving of the control rod cluster, whereby the integrity of the cladding tube can be sustained over a remarkably extended period. Many modifications and variations of the present invention are possible in light of the above techniques. It is therefore to be understood that the invention may be practiced otherwise than as specifically described, within the scope of the appended claims.
046727914	summary	BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to the manufacture of nuclear fuel rods to be incorporated into fuel assemblies for nuclear reactors and, more particularly, is concerned with an improved apparatus for applying an end plug to a fuel rod tube end such that the end plug is guided in a secured manner into the tube end regardless of where the end plug falls in its diametral tolerance range. 2. Description of the Prior Art Fuel elements or rods for nuclear reactors commonly encase the fissible material in thin walled cladding or tubes which serve to support the nuclear fuel during the operation of the reactor. The nuclear fuel, which is usually in the form of cylindrical pellets of enriched uranium dioxide, must be isolated from the environment surrounding the tubes to prevent contact and chemical reactions between the fuel and other materials such as water in a pressurized water reactor. Thus, the nuclear fuel is ordinarily hermetically sealed in each thin walled tube by the use of a pair of opposite end closures or plugs. It is critical that the end plugs themselves be impermeable and mechanically strong to contain the fissible products. It is equally critical that the mechanical connection of each end plug with an end of each tube be free of defects such as discontinuities, cracks and tube distortions which could eventually produce leaks. Present methods of applying the end plugs use close fitting guides to align the plugs with the tube, such as illustrated in FIG. 2. Due to manufacturing tolerances, the necessary clearance between the plug and guide sometimes permits the plug to cock, or tip, as shown in solid line form in FIG. 2, which causes a shaving action on the plug exterior as the plug is rammed home. Thereafter, when the connection is completed such as by welding the plug to the tube, faulty welds commonly result which produce leaking because of discontinuities in the weld joint or connection caused by this shaving action. Also, frequently the plug does not seat properly which increases the likelihood of leakage. Additionally, pieces of the plug are broken off occasionally as it is forced into the tube. The broken pieces not only damage the end plug but also cause foreign objects to be deposited in the fuel rod. Consequently, a need exists for an improved technique for applying an end plug to the tubular end of a fuel rod which will accommodate slight variations in the dimensions of interfitting parts due to unavoidable manufacturing tolerances and thereby increase the resistance of fuel rods to leakage and failure. SUMMARY OF THE INVENTION The present invention provides several embodiments of an improved apparatus for applying an end plug to the end of a fuel rod tube in a manner designed to satisfy the aforementioned needs. In each embodiment, intimate contact is maintained with the end plug by a conformable plug guide means which results in the end plug being securely guided until it enters the hollow tube end. The maintenance of continuous contact between the guide means and the end plug prevents the end plug from being propelled forward out of contact with a ram member being used to move the end plug through the guide means and into the tube end. As a result, the end plug is prevented from cocking, tipping or tumbling within the guide means so that it would not meet the tube end squarely. Accordingly, the present invention sets forth an improved apparatus for applying an end plug to a hollow tube end of a nuclear fuel rod such that a close frictional interfitting engagement will be established between the end plug and the tube end facilitating the formation of a connection therebetween which hermetically seals the fuel rod, the improved apparatus comprising: (a) a housing having spaced inlet and outlet ends, the inlet end adapted to receive the end plug and the outlet end adapted to receive the tube end to which the plug is to be applied; (b) guide means disposed in the housing and having internal surface portions which define an internal guide channel aligned in tandem with the inlet and outlet ends of the housing along a common axis and being of a cross-sectional size smaller than that of an outer external surface of the end plug, the guide means being yieldably expandable radially with respect to the common axis; and (c) means disposed adjacent the inlet end of the housing and movable along the common axis for engaging and moving the end plug from the inlet end through the guide channel to the outlet end, the movement of the plug through the guide channel causing yieldable expansion of the cross-sectional size of the guide means such that the surface portions of the guide means conform to the external surface of the end plug and maintain guiding contact therewith as the end plug is moved through the guide channel. In a first alternative embodiment of the apparatus, the guide means is a bushing disposed in the housing which is composed of resiliently deformable material adapted to expand and conform to the outer external surface of the end plug upon contact therewith and thereby establish and maintain guiding contact with the end plug as it is moved through a central bore of the bushing which defines the guide channel. In a second alternative embodiment of the apparatus, a plurality of elongated runners are mounted for radial movement along a series of passageways which are defined in the housing in spaced relationship to one another and extending generally parallel to and radially from the common axis. A plurality of resiliently expandable members circumscribing the housing and the runners bias them inwardly toward one another. However, the members are yieldable to allow movement of the runners away from one another upon contact with the outer external surface of the end plug for establishing and maintaining guiding contact with the end plug as it is moved through the guide channel defined by inner end surfaces of the runners. In a third alternative embodiment of the apparatus, a plurality of elongated generally cylindrical rolls are mounted for movement radially in a series of recesses which are defined in the housing in spaced relationship to one another about the common axis and aligned generally parallel to one another and with the common axis. A plurality of resiliently expandable elements encircling the housing within respective circumferential slots therein which intersect with the elongated recesses and stretched about the rolls bias them toward inner ends of the recesses. However, the elements are yieldable to allow the rolls to move away from the inner ends of the recesses upon contact with the outer external surface of the end plug for establishing and maintaining guiding contact with the end plug as it is moved through the guide channel defined by inner facing surface portions of the rolls. These and other advantages and attainments of the present invention will become apparent to those skilled in the art upon a reading of the following detailed description when taken in conjunction with the drawings wherein there is shown and described an illustrative embodiment of the invention.
058621954	summary	BACKGROUND OF THE INVENTION 108 nuclear power plants operate in the U.S. without any servicing off-site facility for storage of their spent nuclear fuel rods. When fuel rods can no longer efficiently produce steam, they are taken out of commission and are immediately put into under water storage at a power plant pool where the water absorbs the inherently generated heat. In time the fuel rods decay and the heat generation diminishes. After five years the fissile material is sufficiently spent (decayed/transformed) such that the fuel rods can be stored unconfined in an open air arena. A permanent spent fuel storage facility is planed in the Yucca Mountain region of Nevada. Until then, a "Monitored Retrievable Storage" (MRS) facility is being sought for the intermediate storage of the spent fuel. The author of this patent has worked on many varieties of nuclear material transport equipment and facilities for nuclear fuel since 1958. U.S. Pat. No. 5,448,604 describes an "MRS" facility serviced with railroad equipment. STATEMENT OF THE ART Spent fuel from power plant operation is put into water pools for dissipation of heat as it decays in storage. After about five years or more of radioactive decay, the spent fuel may be stored in the open air using ambient air convection cooling. Eight schemes for intermediate storage have culminated into the "MRS" concept where bundles of spent fuel rods are sealed in a thick steel walled cylinder called a multi-purpose-canister "MPC". In the traditional "MRS" scheme, the "MPC"s are encapsulated in two feet thick concrete and placed in open, outside storage. The concrete casks have provisions for convection air over the exterior surface of the "MPC"s for cooling. The dry-pool invention is an intermediate scheme having a pool having an air manifold system for providing external surface air cooling when the traditional pool water is removed. The facility's roof, walls and access openings are configured to confine the radiation emitting from the "MPC"s being stored. This radiation would otherwise be being absorbed in the conventional pool water. The facility is un-manned and is operated remotely as is the inventors previous storage facility described in U.S. Pat. No. 5,448,604, Sep. 5, 1995. An elevation chase sets and controls the fall height of an "MPC" to a stopping media as it is lowered (placed) or removed from the dry-pool. Before fuel rods are taken from a utility plant water-pond they grouped and put into an "MPC". The fuel rod laden "MPC" is transported from its water storage pool via an appropriate compilation of bridge crane and transporters. Transporters may included a railroad haul in a RR-car having radiation shielding and securement to prevent the "MPC" from tipping. BRIEF SUMMARY OF THE INVENTION Spent nuclear fuel is confined in welded sealed fuel rods. After fuel deterioration, these spent fuel rods are housed in welded, sealed closed multi-purpose canisters "MPC". An "MPC" is typically five (5') feet in diameter and stands 16 feet tall. The invention is an integrated transport, placement, and monitored storage and retrievable facility for the "MPC"s containing the nuclear spent fuel. "MPC"s from a water storage pool are transported from the plant water pool to a dry-pool for storage. Throughout the transfer, the "MPC" is appropriately surrounded with radiation shielding to prevent inappropriate exposure both into and out of the system. Typically an "MPC" is taken from the water storage pool, placed in a shielded transport device (shielded RR-car). Shielded in the transporter, the "MPC" is moved from the plant pool location to the dry-pool location. With the transporter adjacent to the dry-pool, the "MPC" is lifted with a bridge crane and moved sideways out through doors, moved through a shielded corridor adjacent to the dry-pool, then the "MPC" enters the dry-pool, and is then moved in the dry-pool to a storage place on the floor of the dry-pool. When putting an "MPC" into the dry-pool, where there is a significant elevation change, an elevation chase follows the "MPC" such that it may never be subject to a free fall elevation drop of more than 18 inches. One form of the elevation chase of this invention is a column of water where the column of water is lowered below the "MPC" as the "MPC" is lowered to the dry-pool floor. When the MPC approaches the dry-pond floor, the water is then out of the elevation chase and water lock gates are opened to allow the bridge crane to move the lowered to the floor "MPC" to move it about the dry-pool floor to a selected storage location. Each storage location has an in-floor inlet air manifold from an outside air source so that a natural convection of cooling air moves up the sides of the fuel heated "MPC". The natural temperature rise of "MPC" surface heated air continuously pulls in outside air which cools the "MPC". The cooling air rises above the dry-pool and exits out from under the dry-pool building roof, flowing out an end of the building. Under the roof, two ends of the dry-pool are open to the atmosphere to encourage a flow of air across and above the dry-pool. The inlet air manifold is constructed such that should the dry-pool be filled with water, the air manifold also fills with water but water does not leak out of the manifold. The casks are stored secure from tipping with a seismic brace which swings out from a wall and secures the top of the cask to wall to prevent it from tipping in a seismic occurrence. The casks are stored in a designed matrix. The matrix has specific individual storage location addresses for the placement of each casks according to an X-Y Cartesian measured location. The exact address location for each cask is recorded at a control center data base when the cask is placed. Each cask is systematically and routinely monitored for its condition in storage and the tested results are automatically transmitted to and recorded in an off site data base. The data is automatically reviewed and analyzed for a problem condition. When a problem situation is determined, appropriate personnel are automatically notified so that corrections may be implemented.
	abstract	An improved beam forming system for ions used in radiation treatment employs a magnet system of successive quadrupole magnets to convert an ion pencil beam to a fan beam with reduced neutrons production compared with conventional beam spreading techniques using scattering foils.
045284547	description	SPECIFIC DESCRIPTION The transport and storage container for radioactive wastes in accordance with the present invention is composed of cast iron and especially spherulitic or nodular cast iron and is adapted to receive irradiated nuclear elements and similar radioactive materials. Basically it comprises a radiation-shielding vessel 1, the upper end of the wall of which has been made in FIGS. 1 through 3 and which can be of the construction described in the aforementioned copending applications, especially application Ser. No. 966,951, (U.S. Pat. No. 4,278,892) apart from the orientation of the wall bore thereof. The vessel has a closed bottom, not shown, which can be of greater wall thickness, i.e. provided with a thickened portion similar to the thickened portion 6 surrounding the mouth of vessel 1. The mouth of the vessel 1 receives a radiation-shielding or plug-type cover 2 which is of sufficient thickness that escape of radiation through the cover is precluded just as the wall thickness of the vessel and the material from which it is composed or the material which is included therein are selected with respect to the energy of the radioactive emissions from the stored material as to preclude release of radiation. The cover 2 is formed with a plug-type fitting portion 3 and with a flange 4 which are received in a complimentarily-shaped seat 5. At least one additional cover is provided as will be developed below. The wall 1 is formed in the region of the seat 5 and thus the region of the reinforcement bead 6 and within the outline of the shielding cover 2 with the outlet end of a wall bore 7 which can extend to the bottom of the vessel to communicate with the interior thereof (see Ser. No. 966,951--U.S. Pat. No. 4,278,882). While only one such wall bore 7 has been illustrated, it will be understood that a number of such bores can be provided for introducing the radioactive material into the vessel 1, for discharging radioactive material from the vessel, for introducing a control gas, or for monitoring the vessel contents as may be required by law or for safety in the storage or transportion of radioactive material in the vessel. The seat 5 is shown to comprise a wall portion 8 which is complimentary to and sealingly cooperates with the periphery of the cylindrical and/or frustoconical plug portion 3 and is adapted to receive the latter. The bore 7 terminates inwardly of this surface 8 at a shoulder extending perpendicular to the axis of the vessel. A further shoulder 9 receives the flange 4 of the shielding cover 2. The shielding cover 2 is provided with a respective bore 10 for each wall bore 7, the bores 10 serving as connecting bores in which valves or plugs 11 (obturating elements) can be inserted and which can be covered by an additional cover 12. The shielding cover 2 is additionally provided in the region of the seat 5 with control, monitoring or test bores 13 which can receive valves, pressure-monitoring devices, gas analyzers or sample units of any conventional type as represented at 14. These control bores 13 are also covered by the outer cover 12 and lie within the outline thereof. The outer cover 12 itself is received in a recess 15 formed in the open end of the vessel 4 against a shoulder 16. In the embodiment of FIG. 1 the additional cover 12 is formed as a control cover which allows the shielding function of the cover 2 to be monitored. To this end, the cover 12 can define a control compartment 17 with the cover 2 and can be provided with a bore 18 to which a monitoring unit can be attached to communicate with the compartment 17 and determine the leakage of control gas into the latter or the accumulation of radioactive species therein. It is in this form generally that the container, after being loaded, is temporarily stored in or is transported from a nuclear power plant in which the stored radioactive materials were produced. For longer-term storage and more rigorous protection during transportation a further cover 19 can be applied as is shown in FIG. 2. The cover 19 has a plug portion 20 which fits snugly in a recess 21 and a flange 22 which rests upon the upper edge 23 of the vessel 1. While bolts 40, 41, 42 are shown to fix the covers in place in FIGS. 1 through 3, welded lip seals can also be used alone or in combination with bolts (see application Ser. No. 966,951--U.S. Pat. No. 4,278,892 or Ser. No. 243,562, now U.S. Pat. No. 4,450,042. The cover 2 can be provided with seals as described in the last mentioned application and thus forms a first barrier which, by monitoring of compartment 17 through the cover 12, can be controlled to determine the security of the first level of sealing action. Since the cover 19 forms a gap with the cover 12, this gap can constitute a second compartment which is sealed by the cover 19 but which can be monitored. In still another embodiment of the invention shown in FIG. 3, the outer cover can be doubled so that two sealed barriers are provided. In this case, a barrier cover 24 is provided directly above the cover 12 and is welded to the upper end of the vessel 1 in the recess 21 while the outer cover 19a, which can be bolted or welded in place as well with appropriate seals, defines a control cover forming a compartment 25 which can be monitored, e.g. by a sampler 50, in the manner described. As a comparison of FIGS. 2 and 3 will show, the cover arrangements of these two FIGS. can be used interchangeably. The bores 10 can serve to force (pump) radioactive material into the vessels or to evacuate fluid from the vessel after material has been introduced therein, or to receive a sampling lance. The bore 10 of the confronting portion of bore 7 can be provided with O-ring seals 10a which can be omitted when an immersion-type lance is based through the aligned bores 7 and 10. The cover 12 can be formed with a radiation-attenuating material 12a akin to that which may be provided in channels in the wall 1 (see the aforementioned applications) and metal and/or elastomeric O-rings 2a and 2b may be provided as additional seals.
	claims	1. An X-ray diagnostic apparatus, comprising:a tabletop configured to support a subject;an X-ray tube configured to irradiate X-rays and disposed on one side of the tabletop;an X-ray detector configured to detect X-rays that penetrate the subject and disposed on the other side of the tabletop;four diaphragm blade units located between the X-ray tube and the tabletop, a first pair of diaphragm blade units configured to move antithetically in a longer direction of the tabletop, and a second pair of diaphragm blade units configured to move antithetically in a shorter direction of the tabletop, each of the four diaphragm blade units configured to form an exposure field on the X-ray detector;a beam-limiting drive unit configured to drive each of the four diaphragm blade units individually;a center transfer control unit configured to indicate a moving destination at a center of the exposure field;a beam-limiting control unit configured to receive information about a moving amount and a moving direction when the center of the exposure field moves, to control the beam-limiting drive unit to move each of the four diaphragm blade units individually, and to form the exposure field of the moving center that is concentric therewith; andan operating information processing unit configured to calculate the moving amount and the moving direction of the center of the exposure field when receiving an indication from the center transfer operation unit and to output the calculated moving amount and moving direction of the center of the exposure field to the beam-limiting control unit. 2. The apparatus according to claim 1, further comprising:a display control unit configured to display the exposure field on the display and the center position of the exposure field of the X-ray detector is made to correspond to a standard position in the display. 3. The apparatus according to claim 1, further comprising:a display control unit configured to display the exposure field on the display and the center position of the exposure field of the X-ray detector is made to correspond to a predetermined standard position in the display. 4. The apparatus according to claim 1, wherein each of the four diaphragm blade units narrows a detection range where X-rays of the X-ray detector are detected from the longer direction and the shorter direction of the tabletop, respectively, and forms the exposure field on the X-ray detector. 5. An X-ray diagnostic apparatus, comprising:a tabletop configured to support a subject;an X-ray tube configured to irradiate X-rays and disposed on one side of the tabletop;an X-ray detector configured to detect X-rays that penetrate the subject and disposed on the other side of the tabletop;four diaphragm blade units located between the X-ray tube and the tabletop, a first pair of diaphragm blade units configured to move antithetically in a longer direction of the tabletop, and a second pair of diaphragm blade units configured to move antithetically in a shorter direction of the tabletop, each of the four diaphragm blade units configured to form an exposure field on the X-ray detector;a beam-limiting drive unit configured to drive each of the four diaphragm blade units individually;an imaging system drive unit configured to drive the tabletop, the X-ray tube, and the X-ray detector, respectively, so that a detection range of X-ray detector is relative to movement in the longer direction and the shorter direction of the tabletop;an aperture information holding unit configured to hold aperture information about the longer direction of the tabletop and aperture information about the shorter direction of the tabletop;a center transfer operation unit configured to indicate the moving direction of a center of the exposure field; anda judgment unit configured to judge whether part or all of the exposure field exceeds the detection range of the X-ray detector or part or all of the exposure field enters an operation switching area formed at an edge of the detection range based on a moving amount and a moving direction information about the center of the exposure field and the aperture information held in the aperture information holding unit. 6. The apparatus according to claim 5, further comprising:an imaging system control unit configured to control the imaging system drive unit, to move the tabletop, the X-ray tube, and the X-ray detector, and to form an exposure field that is centered on a position of a moving destination when the judgment unit judges that part or all of the exposure field exceeds the detection range; anda beam-limiting control unit configured to control the beam-limiting drive unit to move the each of the four diaphragm blade units individually, and to form the exposure field that is centered on the position of the moving destination when the judgment unit judges that all of exposure field enters the detection range. 7. The apparatus according to claim 5, wherein the beam-limiting controls the imaging system drive unit to move the each of the four diaphragm blade units individually until the exposure field exceed the detection range of the X-ray detector, and the imaging system control unit controls the imaging system drive unit to move the tabletop, the X-ray tube, and the X-ray detector from the exposure field exceed the detection range of the X-ray detector. 8. The apparatus according to claim 5, wherein,the beam-limiting control unit controls the beam-limiting drive unit to move the each of the four diaphragm blade units individually until part or all of the exposure field enters the operation switching area and the imaging system control unit controls the imaging system drive unit to begin moving of the tabletop, the X-ray tube and the X-ray detector, andthe beam-limiting control unit controls the beam-limiting drive unit to decelerate the speed at which each the of the four diaphragm blade units is individually moved from part of the exposure field that enters the operation switching area and to form the exposure field that is centered on a position of a moving destination. 9. The apparatus according to claim 5, further comprising:a display control unit configured to display the exposure field on the display and the center position of the exposure field of the X-ray detector is made to correspond to a standard position in the display. 10. The apparatus according to claim 5, wherein the four diaphragm blade units narrow the detection range where X-rays of the X-ray detector are detected from the longer direction and the shorter direction of the tabletop, respectively, and forms the exposure field on the X-ray detector.
H00002097	description	DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows a longitudinal sectional view of a preferred pin discharge assembly according to this invention. The pin discharge assembly 11 is connected to a source containment vessel 12 which defines a source area, part of which is indicated by the reference numeral 13. Source area 13 is maintained at a source pressure which is typically less than the ambient or terminal pressure existing in terminal areas 16 surrounding the outlet 17 of the pin discharge assembly. The lower pressure in the source area 13 as compared to the terminal pressure in the terminal area 16 tends to create a backflow of gases from terminal area 16 into the source area 13 unless somehow restricted. The pin discharge assembly shown in FIG. 1 preferably includes a containment vessel fitting 20 which is bolted to wall 14 of the containment vessel using bolts 15. Containment vessel fitting 20 has an interior bore 21. An antifriction insert 19 is preferably fitted within the bore 21 to reduce friction between the fitting and elongate pins (shown in FIGS. 8 and 9) which pass through a pin passageway 18 which extends through insert 19 and beyond the containment vessel fitting 20. A commercially available ball valve 90 is advantageously connected at the downstream end 20a of containment vessel fitting 20. Ball valve 90 continues pin passageway 18 therethrough so as to allow elongate pins 50 (see FIGS. 8 and 9) to be passed therethrough. Ball valve 90 includes a ball valve body 91, handle 92, ball 93, and nylon or other antifriction insert 94. Although not necessary, it is desirable to include a quick connect assembly 22 between ball valve 90, if included, or containment vessel fitting 20 and duck valve 30. Quick connect assembly 22 is preferably a commercially available quick connect assembly having a plug portion 23 and socket portion 24. Socket portion 24 includes a detachment sleeve 24a, retaining balls 24b, and socket body 24c. Hansen brand quick connect socket Model No. LL6-S30 and quick connect plug Model No. LL6-T30 are preferred models for this quick connect assembly 22, although many others are alternatively operable. The quick connect assembly 22 is preferably lined by an antifriction insert 19 which extends through plug 23 and defines pin passageway 18. A second antifriction insert 28 advantageously extends within quick connect socket 24 and also further defines pin passageway 18 therethrough. Duck valve 30 is a key component of the pin discharge assembly 11. It is used to prevent backflow and reduce forward flow of gases through the discharge assembly. Duck valve 30 includes a duck valve body 31 which acts as the main structural component of the valve. Duck valve body 31 preferably includes a threaded aperture 32 which can advantageously be used to receive threaded portion 27 of quick connect socket body 24c. A duck valve passageway 98 extends through duck valve body 31 and is shaped with a shoulder 33 toward the upstream end 34 of the duck valve. Shoulder 33 is provided to restrain duck valve lip piece 40 against possible longitudinal motion within pin passageway 18. Shoulder 33 prevents lip piece 40 from moving toward the downstream end 35 of duck valve body 31. Antifriction insert 28 extends inside of lip piece 40 to help guide fuel pins therethrough and prevents the lip piece from moving toward the upstream end 34 of the duck valve body. Duck valve passageway 98 is preferably cylindrical immediately downstream from shoulder 33 in order to better conform to the barrel section 42 of lip piece 40. Thereafter the duck valve passageway 98 diverges toward the downstream end 35, surrounding the tapered section 45 and sealing lip section 46 of lip piece 40. Duck valve passageway 98 preferably is sized to approximate the size of inlet 61 of aspirator means 60 adjacent thereto near the downstream end. Pin passageway 18 also extends through duck valve 30 and communicates in a linear fashion with the related pin passageways 18 in other parts of the pin discharge assembly 11. Pin passageway 18 is defined within duck valve 30 by antifriction insert 28, lip piece 40, and duck valve passageway 98. FIGS. 4 through 9 further illustrate the shape and operation of lip piece 40. FIG. 4 shows lip piece 40 viewed from the top. Lip piece 40 preferably includes a flange 41 which bears against shoulder 33 of duck valve passageway 98. Pin passageway 18 extends through the interior of lip 40. A barrel section 42 is approximately cylindrical and extends from flange 41 at upstream end 43 toward the downstream end 44. A tapered section 45 extends downstream from barrel section 42 to the sealing lip section 46. Sealing lip section 46 has flexible sealing lip means 46a which define and close about a lip opening 47 extending approximately across the downstream end 44 of the lip piece 40. Sealing lip means 46a separate as shown in FIGS. 8 and 9 thereby forming a higher lip opening 47 which allows passage of elongate pin 50 therethrough. The downstream end 35 of duck valve 30 includes an aspirator receiving hole 36 for receiving an aspirator means 60 therein. A threaded aspirator gas supply port 37 is preferably machined into the top of duck valve 30 to allow pressurized gas to be supplied to aspirator means 60. Aspirator 60 continues pin passageway 18 therethrough to allow elongate pins 50 to be discharged therethrough. Aspirator 60 can advantageously be a commercially made aspirator such as Beck brand Ring Jet Air Mover Model R-0200. Aspirator means 60 preferably includes a converging inlet 62 which extends downstream from inlet opening 61. An adjustable venturi sleeve 63 is adjustably mounted within an aspirator body 64, preferably using a threaded connection 65 therebetween. Jam ring 66 is used to secure the relative positions of venturi sleeve 63 and aspirator body 64. Aspirator 60 can advantageously be provided with a threaded downstream end 67 which mates into an evacuator means 70. Other types of end fittings can alternatively be used. Evacuation means 70 preferably includes an evacuation means body 71 which has a pin passageway 18 extending therethrough to linearly communicate with pin passageway 18 extending through fitting 20, ball valve 30, quick connect assembly 22, duck valve 30 and aspirator means 60. Evacuation means 70 preferably includes a plurality of evacuation ports 72 which are preferably positioned about pin passageway 18 at approximately equal angular intervals. FIG. 10 shows preferred form of orientation for the evacuation ports 72 wherein the ports are mounted every 60 degrees. Evacuation means 70 is provided to withdraw gases which are present therein during discharge of elongate pins 50. The evacuation means includes not only the body 71 but also an evacuation means connection ring 73. Radial connection lines 74 extend between connection ring 73 and the evacuation ports 72. Connection ring 73 is also connected to a vacuum system through a vacumm supply line 75. The downstream end 76 of evacuation means 70 is preferably connected into a mechanical seal assembly 100. Mechanical seal assembly 100 includes a mounting piece 101 and a contact piece 102 slidably mounted thereon. A biasing spring 103 is positioned between the contact piece 102 and adjustable backstop 104 in order to bias the contact piece 105 against a control valve disk 81. A control valve 80 is positioned at the downstream end of mechanical seal assembly 100. FIG. 3 shows an end and cross-sectional view taken along 3--3 of FIG. 1. Control valve 80 is preferably a circular valve disk 81 having a pin passage port 82 formed therein. The circular valve disk 81 is rotatably mounted in bearing pillow block 110. Disk 81 rotates as a result of torque applied through shaft 83. The pillow block 110 is mounted on support frame 112 which also supports mounting piece 101 of mechanical seal assembly 100. There are two modes of operation for control valve 80. The first mode of operation is when the pin passage port 82 is aligned with pin passageway 18 near the exit of mechanical seal assembly 100. In this first or open mode of operation the circular valve disk is positioned so that an elongate pin 50 can pass through the entire discharge assembly including the pin passage port 82. In the first mode of operation the pin passage port 82 also allows gas flowing through the aspirator 60 to flow from the pin passageway 18 into the terminal area 16 as will be more fully described below. The second or closed mode of operation of the control valve 80 is when the pin passage port 82 is rotated away from passageway 18 thereby closing the outlet 108 of mechanical seal assembly 100. The pin discharge assembly of this invention is used by connecting it into any appropriate system wherein elongate pins are to be discharged from a source area into a terminal area and where the pressure existing within the source area is lower than that existing in the terminal area. Operation of the pin discharge assembly is commenced by first arranging the various components preferably as shown in FIG. 1 or some equivalent thereto. Pressurized gas such as air or helium is supplied to aspirator 60 through supply line 69 and aspirator supply port 37. Control valve 80 is positioned in the closed mode when elongate pins 50 are not exiting through the discharge assembly. Pin passageway 18 is thus sealed against passage of elongate pins 50 and also against leakage of the pressurized aspirator gas supplied through supply line 69. The aspirator gas in line 69 is preferably in the range of approximately 15 lbs. per square inch gauge pressure. This must be compared against the assumed ambient or terminal area pressure of zero pounds per square inch gauge and the source area pressure of approximately one inch of water column vacuum. The incoming pressurized aspirator gas blocked by control valve 80 pressurizes the pin passageway downstream of lip piece 40 to a blocked aspirator pressure. The soft flexible material from which lip piece 40 is contructed allows the sealing lip section 46 to seal against leakage of gases. The relatively high pressure supplied by line 69 forces the outsides of lip piece 40 inwardly thereby causing the sealing lip section 46 to collapse and seal tightly thereby preventing backflow of aspirator gas or terminal area atmosphere into source area 13. When an elongate pin 50 is to be discharged through assembly 11, then the pin is positioned adjacent to entrance 18a of pin passageway 18 and moved longitudinally thereinto. Control valve 80 is opened before the downstream end 51 (see FIG. 8) of pin 50 reached lip piece 40. Opening of control valve 80 causes compressed aspirator gas to rush through aspirator means 60 thereby reducing the pressure downstream of the lip piece due to the venturi effect. The resulting aspirator venturi pressure existing in the downstream end of duck valve 30 drops below the one inch water column vacuum existing within source area 13. An approximate range of vacuum pressures produced by aspirator 60 in the discharge end of duck valve 30 is two to four inches water column vacuum. The slightly greater vacuum existing in the downstream end of duck valve 30 causes the soft flexible sealing lips 46a of lip piece 40 to slightly separate at lip opening 47 such as shown in FIGS. 8 and 9. The elongate pin 50 can then very easily slide through the duck valve without substantial friction developing between lip piece 40 and pin 50. Lip opening 47 approximately conforms to the shape of the transiting pin 50 as it progresses therethrough to reduce the amount of leakage occurring from source area 13 to the downstream side of lip piece 40. Once the elongate pin has traversed completely through pin passageway 18, the control valve 80 is rotated into the closed positions thereby blocking the exit end 108 of pin passageway 18. Again the static pressure of the incoming aspirator gas supply returns to close the duck valve 30 by compressing sealing lips 46 together. This cycle is repeated for each elongate member which passes from the source area 13 to terminal area 16. The pin discharge assembly 11 has the substantial advantage of allowing control valve 80 to automatically operate the duck valve without further control means being necessary. Opening of control valve 80 also automatically activates aspirator means 60. Evacuation means 70 is advantageously provided to remove leakage which may flow from source area 13 during discharge of an elongate pin. Evacuation means 70 is connected to a source of vacuum which is greater in vacuum then pressure existing within pin passageway 18 at the point where the evacuation ports 72 are provided. Varying the degree of vacuum provided by evacuation means 70 allow either small or relatively large amounts of the gas flowing through pin passageway 18 to be drawn off for treatment and subsequent disposal in case there are any contaminants flowing from source area 13. The pin discharge assembly 11 is constructed according to well known manufacturing techniques in accordance with the description given herein. Most parts can be constructed from a variety of possible metals. Sealing parts can be made from a variety of elastomeric materials. The inserts lining pin passageway 18 are preferably made from nylon or some other material having low friction when the elongate pins are forced therealong. The sealing lip piece 40 is preferably constructed from a relatively thin latex material such as commonly used in the manufacture of household rubber gloves. This description of a preferred embodiment of the invention has been presented for purposes of illustration and example. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. It is intended that the scope of the invention be defined by the following claims.
	description	The present invention relates to nuclear power reactors, and more particularly to an on-line injection system that provides the ability to inject a chemical solution into nuclear power reactors after startup to treat the reactor internals to thereby mitigate intergranular stress corrosion cracking (IGSCC). It is known to use noble metal chemicals in conjunction with hydrogen gas injection to mitigate intergranular stress corrosion cracking (IGSCC) in nuclear power reactors. As a catalyst, noble metal solution is injected into a reactor to assist in the recombination of oxygen and hydrogen. Delivery of noble metals for power reactors is typically done during hot standby, mode 3. No power is generated during this mode when the noble metal is being injected, resulting in a substantial loss of expensive critical path time. In addition, during the startup period of a power reactor, hydrogen cannot be injected with the current system configuration. Under the normal water chemistry conditions, an insufficient concentration of hydrogen is available to recombine with radiolytic oxygen. As a consequence, any existing crack will propagate, leading to a portion of the crack that is not treated with noble metal, and hence not mitigated against IGSCC. The on-line injection system of the present invention solves this problem by providing the ability to inject a chemical solution after reactor startup to treat the reactor internals. Several attempts were made in the chemical delivery process to a power reactor during normal operation. Although each attempt was relatively successful in its outcome, there were major setbacks and improvements with each attempt. Since main steam line radiation increase is a concern with injecting chemical solutions into the reactor, the injection amount used was very closely monitored with the process controller. The initial injection solution needed to be very dilute to minimize its effect on main steam. With a diluted solution, the storage tank was frequently depleted, requiring multiple labor intensive mixing processes to refill the storage tank. The dilution process was also required every time a concentration change is needed. To avoid performing the cumbersome solution mixing process, a higher solution concentration was used. However, a higher concentration equates to an increase in the solution's aggressive characteristic, which may have adverse effects on the wetted components of the pump interior. Along with the harsh ambient temperature of 100+° F. in the reactor turbine building, the conventional off-the-shelf injection pumps (several manufacturer tested) failed within hours of operation. Another concern with the delivery process is loss of chemical due to deposition in the transit line. A shorter residence time in the line would result in less chemical loss. With limited control over volume, boosting the volumetric discharge flowrate with a DI water stream decreased solution residence time in the transit line. This approach also allowed auto-dilution of the chemical, a new feature added to the injection skid. The on-line injection system of the present invention overcomes the adversities described above to provide uninterrupted delivery of chemical solution into an operating power reactor. The injection system of the present invention is designed to deliver a chemical solution into a power reactor through various primary or auxiliary system (Feedwater, Recirculation, RWCU, etc.) tap(s) during a normal operating condition of the power reactor. The process of delivery is via positive displacement pumps. The injection of chemicals is in a concentrated solution form, which is internally diluted by the system prior to discharging from the skid. This method of chemical delivery using the injection system achieves several important accomplishments. First, it minimizes chemical loss due to deposition on the transit line. Second, it enables a higher concentrated solution to be used as the injectant. Third, it eliminates the time consuming laborious process of chemical dilution. Fourth, it raises the chemical solution to the pressure required for injection. Fifth, it prevents solid precipitations out of solution at the injection pump head through the use of a specially prepared unique flush solution. And, finally, on-line injection deposits fresh chemical on new crack surfaces that may develop during a power reactor start-up, shutdown and operation. FIG. 1 is a schematic flow diagram of an on-line injection system 10 used to inject a chemical solution into an operating reactor (not shown) to mitigate intergranular stress corrosion cracking. The system 10 includes two injection pumps, 12 and 14, operating in unison. One pump 14 pumps a concentrated chemical solution from alternative ones of two makeup tanks 16 or 18, while the other pump 12 assists in shortening the chemical solution delivery time by diluting the solution with DI water from a plant source 20. The discharges of both pumps 12 and 14 are combined and mixed at line junction 19 prior to exiting the skid and being injected into the reactor, i.e., via the feedwater line 17. This dilution of the chemical solution accomplishes the task of reducing the residence time of the chemical within the transit tubing 15, while facilitating the dilution of the solution. The system 10 injects the chemical solution into either a primary or auxiliary system through tap 22. Pumps 12 and 14 are positive displacement pumps that are used to regulate the injection capacity, thus providing control over the rate of injecting the chemical solution into the reactor. The amount of chemical solution injected into the reactor from one of the solution tanks 16 or 18 is tracked by gravimetric method using a load cell 24 or 26, respectively. An analog or digital signals 27 or 29 of the chemical solution weight loss is used by a data acquisition system 25 to calculate the rate at which the chemical is being pumped from the solution tanks 16 and 18. Thus, system 10 achieves injection control of the chemical solution into the reactor 17 through the use of electronic balances interfaced with load cells 24 and 26 and the transmission of chemical solution weight loss data through signals 27 or 29 to data acquisition system 25. As shown in FIG. 2, the injection pumps 12 and 14 and isolation valves 28 and 30 are interlocked through the use of a logic controller 40 to turn off chemical injection upon a shutdown condition. Logic controller 40 communicates with pumps 12 and 14 through signal lines 21 and 23, respectively, and controls isolation valves 28 and 30 through AC power lines 31 and 33, respectively. Alarm signals are used to notify the operators, locally or remotely, through Ethernet port 42, that the system 10 is in an undesirable condition and has the potential of being automatically isolated. Normally-closed automatic isolation valves 28 and 30 are located downstream of the injection pumps 12 and 14. There, valves 28 and 30 close upon a trip signal, loss of signal, or a loss of power. There is the capability of viewing the system conditions through a connection at remote locations with an Ethernet line connected to Ethernet port 42. All alarms are displayable via this remote connection. The logic controller 40 provides the following alarm signals: a. High pressure—warning of pressure approaching shutdown condition; b. Low solution—notifies operator that chemical solution in tank is low; c. High flow rate—condition where chemical injection rate differs from set rate; d. Low flow rate—condition where chemical injection rate differs from set rate. The logic controller 40 also provides the following Shutdown signals: a. High pressure—protection of equipment and personnel; b. Low pressure—indicator of a line break; system isolates; c. Pump fault—system isolates upon a pump failure; d. Low-Low solution—chemical solution tank empty, pumps stop, valves isolate. The novel feature of system 10 is its ability to inject a chemical solution with a wide range of pH, while a reactor is operating at full power and temperature. The on-line injection process provides the capability to monitor and control the chemical injection for an optimal application. The selected injection rate is dependent on main steam line radiation (“MSLR”) increases, concentration of the chemical solution in the reactor water and deposited on the internal surfaces of the reactor, and corrosion potential as read by electrochemical corrosion potential (“ECP”) probes within the reactor. The chemical injection rate of injection system 10 can be expressed as follows:Injection Rate=f(MSLRM, Cw, Cs, ECP)Where MSLRM=Main Steam Line Radiation Monitor; Cw=Chemical concentration dissolved in reactor water; Cs=Chemical concentration deposited on surfaces; and ECP=Electrochemical Corrosion Potential. The injection of the chemical solution into the power reactor is maintained at low, but steady concentration. A direct injection of the targeted concentration would require multiple laborious mixing steps or an extremely large solution storage container. The internal dilution capability of the injection system 10 performed using pumps 12 and 14 allows the use of a concentrated solution to be metered into a higher flowing DI water stream. The diluted discharge stream has a shortened residence time, resulting in minor line loss of the injected chemical, while sufficiently delivering the required amount to the reactor. To maintain continuous injection of the chemical solution, as required by the on-line injection process of system 10, it is essential to prevent solid deposition and precipitation on components of the injection pump 14. For this purpose, a novel buffer solution 50 is provided to flush the wetted moving parts of injection pump 14. A recirculation and storage system 54 for storing and circulating the buffer solution 50 through pump 14 is shown in FIG. 3. System 54 includes a canister 53 for storing the buffer solution 50 and lines 51 and 55, respectively, for delivering the solution 50 to a flush housing 56 surrounding piston 52 of pump 14 and returning solution 50 to canister 53. Flush housing 56 contains a portion of solution 50 and a flush seal 58 to prevent the solution 50 from leaking out of housing 56. The flush solution 50 consists of sodium carbonate and sodium bicarbonate powder in a 1:1 ratio (0.025 equal molar of each), resulting in a solution of pH˜10. Without the buffer flush solution 50, solids precipitate out of the chemical solution to crud the injection pump 14 piston and seals. This causes an increased friction on the moving parts that leads to sticking of the reciprocating piston 52, which deteriorate the seal and eventually result in total failure of the pump 14. It is critical that the specific tested buffer flush solution 50 be used to avoid system failure shutdown. The use of conventional flush solutions, such as water, methanol, ethanol, isopropanol, glycerin or sodium hydroxide, has resulted in pump failures due to deposition from the chemical injectant on the piston and the seals of pump 14. Therefore, the specially formulated flush solution, as described above, is used for successful injection of noble metals into a reactor without interruption. The Injection system 10 will deliver a chemical solution, e.g., alcohol, hydrazine, titanium, zirconium, tungsten, tantalum, vanadium and, in particular, a platinum compound [Na2Pt(OH)6], into the reactor vessel during power operation of the reactor. The higher temperature and higher fluid velocities during power operation enhance the penetration of the catalyst into the reactor cracks and crevices. Thus, the Pt transport conditions, which enhance the diffusion of the Pt compound into reactor cracks and crevices, preferably match the oxidant penetration conditions of the reactor. A typical time period for an on-line injection of a chemical solution into an operating reactor is preferably about 1 to 3 weeks. This longer time period is also better suited to enhance the convection, eddy and diffusion transport of the chemical injectant into the cracks and crevices of a reactor. The chemical injection rates are preferably low, so that the reactor water chemical concentration during the application is kept at parts per trillion (ppt) to low parts per billion (“ppb”) levels and the conductivity increase is marginal. Because there may be MSLRM increases associated with the on-line process; preferably, a few preliminary short term (approximately 4 hours duration) chemical injection step tests at incremental addition rates are performed prior to any long term steady-state injection periods. The preliminary injection rates allow the selection of the continuous injection rate that is within the plant operating dose rate (N16) guidelines. The requirements for the chemical injection system and chemical delivery process/method of injecting into an operating power reactor according to the present invention are set forth below. Plant Operating Requirements The required operating conditions for the on-line application are as follows: Reactor operating mode is preferably >70% power. Core flow is preferably >85%. Application Duration Duration of platinum chemical injection is preferably 7 to 21 days.Reactor Water Conductivity Reactor water conductivity during the injection period is preferably <0.3 μS/cm, with an upper limit of <1.0 μS/cm.Process ControlProcess control is by mass of the chemical species injected for each application over 7 to 21 days. The injection rate is dependent on the N16 response of a specific plant as determined by the initial N16 step tests. The rate may, in part, be additionally controlled by reactor water injectant concentration (i.e., 100 ppt platinum in reactor water desired), and conductivity increase limitations.Chemical Input for Subsequent Re-ApplicationsPeriodic re-applications are preferably conducted at six- to twelve-month intervals. If a plant experiences an extended off-hydrogen period, the on-line process should be re-applied as soon as practical following such an event. The mass injected at that time should be the same as the initial application. While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, 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.
	description	This disclosure relates generally to manufacturing equipment and more particularly to a system for monitoring manufacturing plant machinery. Various diagnostic devices are known which monitor or determine a fault in general purpose machinery. Examples of this can be found in the following U.S. Pat. No. 7,010,445 entitled “Automated Fault Diagnosis Device and Method” which issued to Battenberg et al. on Mar. 7, 2006; U.S. Pat. No. 6,549,869 entitled “Expert Analysis Modules for Machine Testing” which issued to Piety et al. on Apr. 15, 2003; U.S. Pat. No. 6,839,660 entitled “On-Line Rotating Equipment Monitoring Device” which issued to Eryurek on Jan. 4, 2005; and U.S. Pat. No. 7,539,549 entitled “Motorized System Integrated Control and Diagnostics Using Vibration, Pressure, Temperature, Speed, and/or Current Analysis” which issued to Discenzo et al. on May 26, 2009. All of these patents are incorporated by reference herein. These conventional devices also typically employ a rigid set of programmed rules to determine health of the machine. In cement manufacturing plants, machine performance is typically monitored by one or more technicians physically walking or driving from machine to machine and either visually observing operating performance at various points for each machine or collecting sensor data through a hand-held data collector at each machine during the walk by inspection. Some of these machines may be at least one mile away from each other. The collected data is subsequently downloaded to an off-line database for later analysis by an operator. This physical walk by monitoring is very time consuming and costly, and does not allow for easily managed and timely analysis of the sensed machine data. Various alarm and temperature fault detection systems have been proposed for use in kiln bearing condition and electric motor monitoring. For example, reference should be made to A. Henningsen et al., “Intelligent Alarm Handling In Cement Plants—Lessons Learned From The Nuclear Industry,” IEEE, 0-7803-0960-x/93, p. 165 (1993), and J. Blaney, “Communication, Protection And Diagnostics For Cement Power Systems,” IEEE, 0-7803-0960-x/93, p. 85 (1993). These proposed systems, however are very crude and do very little, if any, automatic calculation and analysis of the monitored information. Instead, they rely on the operator to manually analyze the information to determine problem causation which will quickly overload the operator with too much data and prevent real-time monitoring, especially if many machines are involved. In accordance with the present invention, a system for monitoring plant equipment is provided. Another aspect provides an automated analysis system wherein software instructions operably analyze sensor data and extract specific spectrum related values to determine mechanical problems in multiple machines. In another aspect, a cement manufacturing system includes sensors for sensing vibration conditions of cement making machines. A further aspect provides a central computer connected to vibration sensors associated with cement making machines, where software instructions perform real-time comparisons and machine performance determinations, and/or evolutionary learning calculations, based at least in part on sensed signals. A method of using machines to manufacture cement, including detecting characteristics associated with a machine and then determining if an undesirable machine condition exists, is also provided. The present invention is advantageous over traditional devices since the present invention allows for essentially instantaneous, real-time data analysis by a centralized computer of the sensed machine operating conditions. This will save significant labor time and expense while also greatly improving the accuracy and timeliness of machine monitoring and maintenance. Certain aspects of the present system also advantageously employ evolutionary learning calculations to improve sensed data analysis and more accurate identification of machine problems. Furthermore, certain aspects of the present system allow for significantly reduced hardware costs by employing a switch matrix and multiplexer computer-to-sensor connection, which inexpensively proves at least 50, and more preferably 64, communication channels. Various aspects of the present system advantageously interface with a hand-held data collector, on-line databases and/or off-line databases, using hard-wired or wireless communications. The present system is ideally suited for use in cement manufacturing machinery, such as cement making kilns, crushers, conveyors, fans and the like. Additional advantages and features of the present invention will become apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. The preferred embodiment of a system for monitoring plant equipment, more preferably cement manufacturing equipment and machinery, may be used to monitor the operating condition of many machines used to make cement, such as Portland cement. In general, the cement manufacturing process begins with extracting raw materials, such as limestone and clay, from a quarry, transporting the materials to crushing machines which reduce the size of the extracted rock, and conveying the crushed rock to grinders. Corrective materials such as iron, minerals and sand are mixed to the crushed material before it enters the raw mills for grinding, drying and pulverizing. The pulverized material is then transported to kiln machines where it is heated until the material forms clinker, which is subsequently cooled by fans. Next, the clinker is transported to storage silos and later sent to clinker grinding mills where it is mixed with gypsum and other materials, whereafter it is transported to storage silos in its final cement form. The present system employs a computer controller, software and sensor configuration to automate and improve the reporting and analysis of the operation of the many cement manufacturing machines for problem and fault identification, maintenance planning and for historical trend tracking. The present system advantageously minimizes machinery and manufacturing downtime, provides real-time data, improves the quality of data collection and analysis, and significantly reduces the labor, time and cost to collect and analyze the equipment data. More specifically, referring to FIGS. 1 through 5, the present system 51 includes a first computer controller terminal 53 connected to an ethernet communications network 55, and a second computer controller terminal 57 connected to a wireless communications modem 59 via wireless communications 61; the modem is also connected to the ethernet communications network 55. A personal digital assistant (“FDA”) controller 63, such as a cellular telephone with e-mail access, is also connected to modem 59 or a cellular telephone tower via wireless communications. A computer server 65 is additionally connected to the ethernet communications network via an ethernet cable. FIG. 3 illustrates data flow in an FPGA-based data acquisition device. The device receives analog data continuously from accelerometers and then carries out a 24-bit high resolution analog-to-digital conversion. Thereafter, data is sent to the server through either ethernet communication ports or through wireless communications. FPGA-based data acquisition boards 67 are connected to the ethernet communications network via ethernet cables and these boards are connected to associated dynamic signal inputs 69, for example, accelerometers. FIG. 2 shows data flow from a management box 71 which receives the digital signals from the central computer through any of the computer terminals and then converts the signals back into their original analog form received from the accelerometers. Management box 71 then generates a series of analog data through its BNC output connections, based on a predefined, timed sequence that scans through all measured points in order to simulate the manual data collection process where regular data collectors can connect and acquire data in a point-by-point manner. BNC management box 71 is connected to computer terminal 53 via a USB interface 73. The BNC management box further includes an FPGA-based controller having a sample buffer, data flow code, sample clock and interface code. Multiple 24-bit digital-to-analog converters 77 convert controller 75 outputs to analog form and transmit the signals to BNC connectors 79. There is two way communication between interface 73 and controller 75. Each FPGA-based data acquisition board 67 includes an ethernet and wireless communications interface 81, an FPGA-based controller 83, multiple 24-bit analog-to-digital converters 85, and a terminal block 89. A multiplexer switch matrix 87 is only utilized where channel count exceeds four monitored locations per machine. Controller 83 further includes a sample buffer, data flow code, sample clock and interface code. Terminal block 89 is connected to a data acquisition device 91 which is mounted within an enclosure attached to the corresponding machine to be monitored. An accelerometer sensor is mounted adjacent a moving component of interest within a corresponding monitored machine 93. For a proximity sensor, there is preferably a 2.5 millimeter gap between the component of the machine being monitored and a tip of sensor 95. A cable 97 connects sensor 95 to a proximitor circuit 92 (see FIG. 4), which powers the sensor and sends the signal to data acquisition device 91. Furthermore, a power supply 99 is connected to and powers the proximity sensor circuitry. An exemplary real-time and continuously monitored machine includes a pair of kiln drive systems 119 and 119′. These are illustrated in FIGS. 6-10. The kiln 101 includes a rotatable hollow tube 103 through which the raw materials are heated and moved to form clinker, a south side drive system 119 and a north side drive system 119′. Each kiln arrangement further includes piers 105, 107 and 109 upon which are mounted pillow blocks 111, 113, 115 and 117, and the two main drive assemblies 119 and 119′. Supporting slip rings 121, 123 and 125 concentrically surround and move with kiln tube 103 and are engaged by rollers journaled by shafts. Approximately 36 sensors 131-153 are employed to continuously monitor vibration of the kiln arrangement in a real-time manner. Exemplary pillow block 113 includes a cast and machined iron housing 171 having lateral flanges 173 bolted to pier 105 and a central opening 175 through which extends a shaft 177. A ball bearing assembly 179 is provided within opening 175 of pillow block 113 and rotatably engages the outside diameter surface of shaft 177. Additional ring seals 181, O-rings 183, and stabilizer rings 185 are provided. Oil is provided within pillow block 113. Shaft 177 rotatably drives a small pinion gear 187 which, in turn, drives the much larger girth gear 189 affixed around an outer surface of tube 103. Of particular note, sensor 135H designates a substantially horizontally oriented and enlongated accelerometer, 135A designates a substantially axially oriented and elongated accelerometer and 135V designates a substantially vertically oriented and elongated accelerometer, which all sense and detect vibrations from the bearing 179, shaft 177 and associated gears 187 and 189. A gear box 201 of each main drive assembly 119 and 119′ is best shown in FIGS. 11 and 12. Gear box 201 includes an input shaft 203 connecting to and rotatably driven by an armature of an electric motor 205 (see FIG. 6). Input shaft 203 rotatably drives and rotates an output shaft 205 through a set of interengaging gears 207, 209, 211 and 213 of different ratios. Each shaft associated with gears 207-213 have at least a pair of associated bearing assemblies 215. Accordingly, sensor 141H is a substantially horizontally oriented accelerometer, sensor 141V is a substantially vertically oriented accelerometer, sensor 139H is a substantially horizontally aligned accelerometer, sensor 139V is a substantially vertically aligned accelerometer, and sensor 143 is a substantially horizontally aligned accelerometer, which all sense and detect vibrational characteristics of the adjacent shaft, bearings and gears, when the components of the gear box are rotated. Most of the other sensors for kilns 101 and 103 are also rotational vibration accelerometer sensors, however, it is alternately envisioned that temperature sensors and electric motor voltage and/or current sensors may optionally be employed. Each of the accelerometer sensors associated with the pillow blocks provide high sampling rates with a qualitative signal. For example, at least 1,000 analog samples are sensed per second from each sensor, and more preferably, the samples are sensed and sent approximately 16,000 per second. As will be discussed in more detail hereinafter, the central processing unit and software therein use a signal sent by the sensors to determine defects or potential maintenance problems in the corresponding bearings, gears, shaft and other rotating machinery. This information also allows the computer software to determine if there is undesired looseness in the moving parts or if there is too much friction caused by insufficient lubricant. Moreover, a torque sensor and/or strain gauge is disposed between each coupling disc 217 (see FIG. 6) and the corresponding accelerometer vibration sensor 137. The disc torque sensor measures the torque of the connecting shaft, and torsional vibration can be automatically determined by the software. Thus, the relative difference between kilns drives 119 and 119′ can be determined by comparing their respective torsional vibration since the same torque is desired. FIGS. 13 and 18 illustrate a crusher machine 231 employed prior to the kiln. An electric motor 233 operably rotates a set of shafts 235 through various couplings and gears 237, which in turn rotate a crusher input shaft 239. A crushing roller or other such member is rotated by input shaft 239 in order to reduce the size of the raw limestone and other such raw material. A raw material hopper 241 is located above input shaft 239 and the associated crushing shaft. Furthermore, sets of bearing assemblies 243 are associated for journaling input shaft 239 as well as other associated transmission shafts therein. A substantially axially oriented accelerometer sensor 245A and a substantially vertically oriented accelerometer sensor 245V perform vibration sensing at crusher input shaft 239 and the adjacent components such as bearings and gears. Additionally, substantially horizontally oriented accelerometer sensors 247 and 249 are attached adjacent the driving end and non-driving end, respectively, for sensing rotational vibration associated with electric motor 233 and the associated transmission component and bearings rotated therewith. One out of eight similar milling machines 271 is shown in FIG. 14. Two of the milling machines reduce the size of the raw material before the kiln, four of the milling machines reduce the size of the clinker after the kiln and two of the milling machines are employed for the core fuel. A pair of electric motors 273 and 275 drive their respective gear boxes 277 and 279 via rotating shaft 281, gears and couplings. These transmission components operably rotate rollers or the like to reduce material size. A substantially horizontally oriented accelerometer sensor 283 is positioned adjacent the non-driving end of motor 273 while a substantially horizontally oriented accelerometer sensor 285 is positioned adjacent the driving end of motor 273 for vibration sensing associated with the motor and driven transmission components. Furthermore, substantially axially oriented and vertically oriented accelerometer sensors 287A and 287V are located adjacent an input shaft of gear box 277 for sensing the rotational vibration characteristics associated with the shafts, bearings and gears in gear box 277. Similar sensors are employed for motor 275 and gear box 279 as is shown in greater detail in FIG. 15. Electric motor 275 drives the transmission components within gear box 279, which in turn, rotate a separator machine 291. An output shaft 293 and coupling 295 more particularly couple the transmission to a fan or cage 297 of separator machine 291. Multiple sets of bearings are also disposed within the separator machine, gear box and motor. A non-contact, proximity sensor 299 is mounted to separator machine 291 adjacent input shaft 293 and its associated bearings. Sensor 299 measures the relative displacement and provides an output DC signal. Sensor 299 further measures dynamic vibration by providing an output AC signal, which generates a spectrum for later analysis by the central processing unit and software. The use of a proximity sensor for the vertical separator shaft measures the relative clearance measurement in a non-contact manner and is advantageous for slower speeds such as with the separator shaft. Additional accelerometer-type vibration sensors may be optionally provided in the gear box and motor. Referring to FIG. 16, a secondary crusher machine 301 is provided between the primary crusher and the kiln. Secondary crusher machine 301 includes an electric motor 303, an output pulley 305, a belts 307, an input pulley 309 and an input shaft 311. Input shaft 311 is rotated in response to energization of a raw material crushing shaft 313 or the like. A substantially horizontal accelerometer vibrational sensor 315 is mounted adjacent to a non-driving end of motor 303 and a substantially horizontally oriented accelerometer vibrational sensor 317 is mounted adjacent a driving end of motor 303. Furthermore, a substantially axially oriented accelerometer vibrational sensor 319A is disposed adjacent to input shaft 311 and its substantially vertically oriented accelerometer vibrational sensor 319V is located adjacent input shaft 311. The sensors measure vibrations associated with movement of associated shafts, gears and bearings. FIG. 17 shows a fan machine 331 which is employed in many different locations throughout the cement manufacturing plant. Approximately 15 or more fans are monitored in a real-time and continuous manner as further discussed hereinafter. An electric motor 333 operably rotates an output shaft 335 which is coupled to an input shaft 337 by a transmission coupling 339. A set of fan blades 341 are operably rotated with input shaft 337. A pair of pillow blocks 343 and 345, each having sets of bearing assemblies therein, support input shaft 337. A substantially horizontally oriented vibrational accelerometer sensor 351 is provided at the outboard bearing location for pillow block 343 and a substantially horizontally oriented vibrational accelerometer sensor is provided for the inboard fan bearing at pillow block 353. A substantially horizontal vibrational accelerometer sensor 355 is located adjacent a drive end of motor 333 and a substantially horizontally oriented vibrational accelerometer sensor 357 is mounted adjacent a non-drive end of motor 333. Referring now to FIGS. 1-4 and 19, analog vibration signals are collected by accelerometer sensor 95 permanently mounted on rotating components within the equipment 93 being monitored. These analog signals are converted into digital form in data acquisition devices 91 and then transmitted to a server 65 acting as a central processing unit or computer controller. This analog-to-digital conversion occurs in the data acquisition boards which communicate with the network by either ether net protocols and network switches, or wireless protocols and access points 59. Server 65 houses essentially all of the data processing and analysis algorithms and software, manages data flow from all acquisition boards and performs a set of parallel tasks for data analysis. The server then directs the results to the display terminals 53, 57, 63 and a control room display monitor 401. Server 65 and its programmable software instructions monitor all of the measured sensor points and optionally, continuously analyze the data with a self-learning multi-layered, neural network algorithm that performs pattern recognition and identifies machine defects or potential maintenance concerns. The software then posts or outputs the results and alerts for specific actions. The terminal computers 53 and 57 post a set of analysis features that receive live data from server 65 and perform octave analysis, power spectra, zoom FFT, FRF analysis, torsional analysis, order analysis, order tracking, tachometer processing, and Orbit, Bode, Waterfall, and Cascade plots. A fiber optic converter 403 is located within the same enclosure housing of each data acquisition device 91 and transmits the sensor output signal through optical fibers 405 to server 65. Monitor 401 is located in the main, centralized control room for the entire manufacturing plant. Monitor 401 displays the sent information and any alarms in a simplistic fashion. This control room display may take the form of a virtual illustration of the entire manufacturing plant, or portions thereof, such as those displayed in FIGS. 20-22, with various colored lights or other illustrated warning indicia being visually seen if a problem or other undesired situation occurs at any sensor point. Computer terminal 57 is for an operator, who is a data analyst or maintenance supervisor, to review the detailed data calculations, trends and other output from the monitoring software. This computer terminal 57 is in a centralized and remote location spaced away from the equipment being monitored and has the capability to analyze and manipulate the real-time and continuously monitored sensor information as well as information from off-line databases. Computer terminal 53 is also remotely located away from the monitored machines and is used by computer personnel to make programming changes to the software instructions employed in server 65, if necessary. A TIS web host 407 is connected to the network via ethernet, and provides executive and routine maintenance reports for the entire manufacturing plant operations. Moreover, PDA devices 63 are connected to the network for receiving warning alarms and other information of undesirable situations occurring through e-mail communications and the like, thereby notifying plant engineers and technicians who may not be present at the control room or analyst computer terminals. The present system currently monitors approximately 800 of the cement manufacturing equipment in an off-line manner, where a handheld unit is employed to collect data from running equipment and download the collected data in an off-line database for manual analysis. However, in the presently preferred embodiment, about 80 equipment are monitored on a real-time and continuous basis due to the manufacturing importance or cost of the associated equipment. Furthermore and optionally, the continuously monitored equipment signals can be routed to the hand held unit through the data interface devices 411 (see FIG. 19) as an alternative remove collection method for the off-line database. The software allows for adaptive monitoring of the equipment through the sensors, for the on-line and continuously monitored equipment. Based on the severity of the potential problem and the criticality of the specific equipment, the software can selectively take snap shots of data and trend information, the frequency of which can be automatically increased if a problem is detected. This allows for more aggressive monitoring if the software automatically determines that alarm or fault levels of a monitored location are increasing. The software is intelligent and self-adjusting where it automatically adjusts its fault detection criteria based on the equipment running conditions. For example, equipment running speeds are continuously changed and optimized for the manufacturing process by the control room operators. Furthermore, a switch matrix and a multiplexer are employed to most optimally connect the sensors to the server while providing at least 50 channel data acquisition and more preferably, 64 channel data acquisition, but at a significantly reduced hardware cost compared to if multiplexing was not employed. Optionally, the software can further perform generally real-time, evolutionary learning calculations based at least in part on signals from the sensors to determine if operating problems occur, identify the actual mechanical problem based on the data, and report the results based on historical data on associated maintenance. This allows the software to automatically identify the actual problem occurring based on various characteristics of the qualitative analog sensor signals while also accounting for prior maintenance trends, and field observations relative to prior sensor signal data. FIGS. 20 through 23 show various software application interface displays for the monitor of analyst computer terminal 57 (see FIG. 19). FIG. 20 shows the main interface of the software for alarm and notification. In particular, this is the display associated with a “plant overview” tab 421 (versus a hidden “control” tab 423). An alarm list 425 is displayed in a chart at the bottom of the screen display. This main interface visually shows a simulated representation of the manufacturing plant machinery with various sensor indication boxes 427, 429, 431, 433, 435, 437, 439, 441, 443, 445, 447, 449, 451, 453, and 455. These indication boxes are associated with the real-time, continuously monitored sensors and are shown in red if there is a problem, green if a sensed data is satisfactory and a blinking yellow if maintenance is recommended but not yet a problem. This screen display shows virtual finish mills 481, fans 483, kilns 485, coal-fuel mills 487, rolling mills 489, primary crusher 491, secondary crusher 493, smokestacks 495 (which are monitored in a non-continuous, off-line manner) and various storage bins 499 which are not monitored. The term “crusher” may be generally used throughout this disclosure to include mills, crushers and grinders. FIG. 21 illustrates a route acquisition interface where the associated “controls” tab is shown and the “plant overview” tab is hidden. This screen display also provides virtual illustrations of equipment throughout the manufacturing plant depending on which section of the plant is selected for display. An indication box 501 for a first roll mill 505, an indication box 507 for a second roll mill 509, an indication box 511 for a first fan 513, and an indication box 515 for a second fan 517 can be shown in red, green or yellow. The indication boxes are green if the sensored data has not yet been transferred to the data interface devices 411 (see FIG. 19) within a predetermined period of time. A red box designation indicates that the sensored data has already been acquired within the predetermined time period and a linking yellow colored box indicates that the signal is being acquired. The predetermined time can be set for once per week, once per day or in a manual manner by the analyst. It should be appreciated that alternate color designations or graphic designs for any of the interfaces can be employed. FIG. 22 illustrates a virtual plant equipment layout for a different area of the manufacturing plant. This display shows signal acquisition color indication boxes like that for the prior figure. In this plant area, indication boxes 521 and 523 are associated with sensors for crushing machines 525 and 527. Color display circle 529 is associated with the sensors for electric motor 531. Furthermore, an indication circle 533 is for electric motor 535 associated with crusher machine 537 while indication boxes 539 and 541 are associated with sensors for different portions of crushing machine 537. Additional conveyors 543 and storage bins 545 are illustrated but not monitored in this exemplary embodiment. FIG. 23 shows another application interface screen display for the present system. This computer screen display shows the “control” tab 423 view with the “power spectral peaks” sub-tab 571 activated. Alternately, “weighted data” tab 573, “octave spectrum” tab 575 or “RMS” (“route/mean/squared”) level tab 577 can be activated to display different forms of the wave form data. A channel control category 579 can be selected by the analyst in order to select which real-time sensor data is to be displayed. The frequency range values can be entered at input area 581, the number of lines value can be entered at 583, the peak search settings, such as single or multiple peaks, can be input at 585, and the scaler or dynamic limits can be entered at 587. This interface shows a vibrational spectrum, or alternately wave form, from the selected sensor. It is noteworthy that in one software module, the software employed in the present system automatically compares the sensed vibrational peak values to predefined values associated with the machine component properties. The software then automatically calculates differences and automatically determines if there is a problem, and the severity of the problem, for different frequencies. These predetermined values are essentially the nominal harmonic vibration characteristics for a rotating bearing, gear or shaft as determined from the supplier's specifications, a textbook or prior field use during optimal conditions. This desirable target data is stored in memory of the central processing unit for quick access by the microprocessor of the central processing unit. The present software allows for very quick and efficient real-time and continuous comparisons of the monitored sensor values as compared to the target values for all of the continuously monitored sensors. The software and central processing unit controller automatically provide historical trends, alarms for problems, less urgent maintenance or inspection notifications, and the, like for thousands of sensed values every second. The programmed instructions for the computer software of the present system are stored in random access memory of the central processing unit, or alternately read-only memory, a removable disc, tape or other storage device. Referring to FIGS. 24A and 24B, software flow diagrams show a main interface software logic for the alarm and notification interface and for automatically determining if an e-mail or other error reporting message needs to be sent at box 611 (see FIG. 27) to a remote communications device 63 (see FIG. 1) carried by the plant engineer or technician. This corresponds to the interface screen display of FIG. 20. Trapezoidal boxes such as “tab selection” indicate analyst manual entries, diamond-shaped boxes such as “value changed in buttons cluster” indicate logical computer operations, rectangular boxes such as “vibration analysis” indicate computer processes, while generally ovallular-shaped boxes such as “display main interface tab” indicate final computer processes. If the alarm limit is exceeded, then the software updates the alarm list by displaying the newly determined problem. If it does change, then the update alarm limits the updated and reevaluated against newly sensed data values. If the list is not changed, then no update is needed. The software often updates the main interface, such as by providing a different color to the displayed indication boxes in FIG. 20, and it refreshes the main display. More specifically, the data box 601 indicates stored data on the CPU server that is sensed from the data acquisition devices, then evaluates data against the alarm limits calculation in comparison box 603 if performed in the CPU server, and the tab selection box 605 requires manual selection between the plant overview and controls tabs from FIG. 20. FIGS. 25 and 26 are software flowcharts that correspond to the screen display and analysis of FIG. 23. This software routine allows for the manual analysis operations module of the sensed data. As previously mentioned, the data can be automatically compared and analyzed, or it can be manually compared and analyzed by the operator, thereby providing different operations possibilities depending upon the equipment needs. FIG. 27 shows the software flowchart for the continuous acquisition process from data acquisition devices 91. This routine is automatically conducted by the software and controller for all of the real-time and continuously monitored sensors which are associated with the most critical or expensive machinery components. Referring now to FIG. 28, a vibration analyst application software flow diagram is shown. Incoming sensor data is received in box 631 and the physical/mechanical perimeter values for a specific machinery component are received in box 633. Fast Fourier transform procedures are used to match the physical/mechanical properties to the real-time sensor data and the software routine 635. Predefined rules with regard to comparing sent data to target values are indicated by boxes 637 and 639, while boxes indicated by 641 store and track historical trends for prior years for routine maintenance reports and to analyze long-term machine component vibrational trends. This software routine triggers alarm limits if unbalanced conditions, for example, are determined by the software and controller, and then alarm or fault severity levels are calculated, and subsequently, the appropriate visual, audio and/or written alarm indications are activated in an automatic manner. For example, a high alarm requires immediate attention and a high/high alarm requests the control room operator to manually turn off power to that specific machine in a severe situation. A route acquisition interface software flow diagram is shown in FIG. 29, which corresponds to FIG. 21. This is used by the analyst to route the automatically collected data to the hand-held data acquisition units 411 (see FIG. 19) which are used by the plant technicians for intermittent monitoring on a non-real time basis, and for manual analysis. The actual software coding algorithms are shown in FIGS. 30A through 32M. These software charts are shown in the Labview® coding language from National Instruments Corp. While the preferred embodiment of the present system for monitoring plant equipment has been disclosed, it should be appreciated that other variations may be employed. For example, additional machinery components may be monitored on a real-time and continuous basis and other types of sensors, detectors and monitoring devices may be provided, although various advantages in the present system may not be realized. Furthermore, additional, less or different computer and communications hardware items may be used although certain functions and advantages of the present system may not be achieved. Alternate software logic and instructions may be used although certain benefits of the present system may not be fully achieved. Furthermore, certain aspects of the present system may be employed for machinery and equipment not associated with cement manufacturing, although various advantages may not be gained. For example, specific comparative, analysis and reporting features of the present software can be alternately utilized for movement sensing of other manufacturing plant machinery outside of the cement industry, however, the preferred embodiment disclosed hereinabove utilizes this software in an advantageous manner that may not otherwise be obtained. Similarly, the analog-to-digital-to-analog sensor signal conversion and transmission to the CPU through multiplexed channels may be employed for various other machine sensing and other industries, however, the cement manufacturing plant advantages may not be fully obtained. It should be appreciated that other modifications and variations may be made to the preferred system without departing from the spirit and scope of the present invention.
043615058	description	DESCRIPTION OF THE PREFERRED EMBODIMENTS Pelletization of radioactive liquid waste proceeds in a process sequence of drying-making powder-pelletization of a liquid waste. The present invention has been established on the basis of a finding that some binder dissolves in a radioactive liquid waste in a solution state or a slurry state and attain an excellent binding effect in the drying step and the pelletizing step in the process. A preferable embodiment of the present invention are applied to a boiling water-type nuclear power plant will be described in detail, referring to FIG. 1. A conduit 2 for introducing a radioactive regeneration liquid waste (main component being sodium sulfate) produced by regenerating granular ion exchange resin in a desalter (not shown in the drawing) is connected to a tank 1. A conduit 3 having one end connected to the tank 1 is connected to a concentrator 6 at another end through a valve 4 and a pump 5. A tank 7 is connected to the concentrator 6. A conduit 8 connects the tank 7 to a mixing tank 12 through a valve 9, a pump 10 and a flow rate meter 11. An agitator 13 is provided in the mixing tank 12. A conduit 15 with a valve 16 connects the mixing tank 12 to a tank 14. A concentration meter 17, for example, an electro-conductivity meter, for measuring a concentration of sodium sulfate is provided at the tank 7. Numeral 18 shows a controller. A conduit 19 connects the mixing tank 12 to a thin film drier 22. A valve 20 and a pump 21 are provided on the conduit 19. Detailed structure of the thin film drier 22 will be described below, referring to FIGS. 2 and 3. The thin film drier 22 is provided with a rotating shaft 324 with pivotally movable blades 325 within a shell 323. The rotating shaft 324 is supported by an upper bearing 329 and a lower bearing 330. A motor 331 is connected to the upper end of the rotating shaft 324. A vapor outlet 333 and a liquid inlet 332 are provided at the upper part of the shell 323. The conduit 19 is connected to the liquid inlet 332. A bottom cone 334 with a powder outlet 335 is provided at the lower part of the shell 323. A mist separator 337 and a distributor 336 are arranged at the upper part of the shell 323 to form a vapor chamber 338. The distributor 336 and the mist separator 337 are fixed to the shell 323. A jacket 339 is provided around the shell 323 to surround the shell 323, and is provided with a heating medium inlet 340 and a heating medium outlet 341. The pivotally movable blades 325 are pivotally movably fixed by pins 328 to support rings 327 fixed to the rotating shaft 324 by support arms 326. A conduit 43 connected to the powder outlet 335 of the thin film drier 22 is connected to a powder hopper 45 through a valve 44. A moisture meter 46 is provided at the powder hopper 45. Numeral 47 shows a controller. A conduit 48 having one end fixed to the bottom of the powder hopper 45 is connected to a pelletizer 53 at another end through a three-way valve 49. A conduit 50 connects the three-way valve 49 to a tank 51. A conduit 52 is connected to the tank 51. Detailed structure of the pelletizer 53 will be described below, referring to FIG. 5. The pelletizer 53 has a pair of rolls 555 and 557 within a casing 554. A large number of recesses 556 and 558 exist on the peripheral surfaces of the rolls 555 and 557, and the rolls 555 and 557 are arranged so that their peripheral surfaces can be counterposed to each other. The rolls 555 and 557 are fixed to rotating shafts 559 and 560, respectively. The rotating shafts 559 and 560 are connected to motors (not shown in the drawing), respectively. A rotating shaft-moving device, which can move the rotating shaft 560 in a direction of arrow 565, is provided at the shaft 560, though not shown in the drawing. A hopper 561 is provided at the upper part of the casing 554. A screw feeder 562 is arranged within the hopper 561. A motor (not shown in the drawing) is connected to the upper end of a screw feeder shaft 563. The conduit 48 is inserted into the hopper 561 so as not to interrupt the rotation of the screw feeder 562. A conduit 54 is provided at the bottom of the casing 554 of the pelletizer 53. The conduit 54 is connected to a pellet hopper 55. A conduit 56 provided at the bottom of the pellet hopper 55 is open over a belt conveyor 57, which is a pellet transfer machine. The belt conveyor 57 extends to a position right above a pellet chute 59 of a storage tank 58 disclosed in U.S. patent application Ser. No. 55,151. A pellet suction conduit 60 with a blower 61 is inserted into the storage tank 58. The radioactive regeneration liquid waste produced at the regeneration of granular ion exchange resin is introduced into the tank 1 through the conduit 2. The regeneration liquid waste is substantially an aqueous solution of sodium sulfate. The regeneration liquid waste is fed into the concentrator 6 through the conduit 3 by driving the pump 5. The regeneration liquid waste is concentrated in the concentrator 6, and a concentration of sodium sulfate is increased thereby. The regeneration liquid waste whose sodium sulfate concentration has been concentrated to about 20% by weight is led to the tank 7. The concentration of sodium sulfate in the regeneration liquid waste is measured by the concentration meter 17. A concentration signal thus obtained is transmitted to the controller 18. The regeneration liquid waste in the tank 7 is fed into the mixing tank 12 through the conduit 8 by driving the pump 10. A flow rate of the regeneration liquid waste is measured by the flow rate meter 11. A flow rate signal thus obtained is transmitted to the controller 18. The controller 18 determines an absolute amount of sodium sulfate supplied to the mixing tank 12 from a product of the concentration signal and the flow rate signal. An aqueous 20 wt.% solution of N-.beta.-(aminoethyl)-.gamma.-aminopropyltrimethoxysilane [NH.sub.2 (CH.sub.2).sub.2 NH(CH.sub.2).sub.3 Si(OCH.sub.3).sub.3 ], which is a kind of the silane coupling agent, is in the tank 14. OCH.sub.3 of NH.sub.2 (CH.sub.2).sub.2 NH(CH.sub.2).sub.3 Si(OCH.sub.3).sub.3 is converted to OH by hydrolysis. The aqueous solution of NH.sub.2 (CH.sub.2).sub.2 NH(CH.sub.2).sub.3 Si(OCH.sub.3).sub.3 is supplied to the mixing tank 12 through the conduit 15 by opening the valve 16. The degree of opening of the valve 16 is controlled in accordance with the absolute amount of sodium sulfate by the controller 18. That is, if the absolute amount of sodium sulfate is increased, the degree of opening of the valve 16 is increased. Relations between the content of NH.sub.2 (CH.sub.2).sub.2 NH(CH.sub.2).sub.3 Si(OCH.sub.3).sub.3 in pellets formed by adding NH.sub.2 (CH.sub.2).sub.2 NH(CH.sub.2).sub.3 Si(OCH.sub.3).sub.3 and percent pellet fall breakage are shown in FIG. 6, where the percent pellet fall breakage shows a percentage of pellets broken when the pellets containing NH.sub.2 (CH.sub.2).sub.2 NH(CH.sub.2).sub.3 Si(OCH.sub.3).sub.3 is made to fall from the height of 3 m. When the content of NH.sub.2 (CH.sub.2).sub.2 NH(CH.sub.2).sub.3 Si(OCH.sub.3).sub.3 in the pellets exceeds 2% by weight, the pellets are hardly broken. However, an increase in the amount of the silane coupling agent in the pellets means a corresponding increase in the amount of the radioactive waste, or the number of drums, and thus it is desirable that the amount of the silane coupling agent to be added is smaller. Preferably the amount of the silane coupling agent is 2% by weight. The controller 18 opens the valve 16 in accordance with the concentration of sodium sulfate and the absolute amount of sodium sulfate supplied to the mixing tank 12 and supplies the aqueous solution of NH.sub.2 (CH.sub.2).sub.2 NH(CH.sub.2).sub.3 Si(OCH.sub.3).sub.3 to the mixing tank 12 so that 2% by weight of NH.sub.2 (CH.sub.2).sub.2 NH(CH.sub.2).sub.3 Si(OCH.sub.3).sub.3 as the silane coupling agent can be contained in the pellets. The regeneration liquid waste and the aqueous solution of NH.sub.2 (CH.sub.2).sub.2 NH(CH.sub.2).sub.3 Si(OCH.sub.3).sub.3 are stirred and mixed in the mixing tank 12 by the stirrer 13. The regeneration liquid waste containing NH.sub.2 (CH.sub.2).sub.2 NH(CH.sub.2).sub.3 Si(OCH.sub.3).sub.3 is supplied into the thin film drier 22 from the liquid inlet 332 through the conduit 19 by driving the pump 21. The regeneration liquid waste is supplied into the inside of the shell 323 from the liquid inlet 332, uniformly distributed in a circumferential direction by the distributor 336, and made to flow down along the inside surface of the shell 323 by gravity. The rotating shaft 324 is revolved in the direction of arrow 364. The pivotally rotatable blades 325 are also moved in the direction of arrow 364 with the revolution of the rotating shaft 324. At that time, the pivotally rotatable blades 325 can be rotated around the pins 328 as centers, and thus can be extended outwardly by the action of centrifugal force. Thus, the tip ends of the pivotally rotatable blades 325 move in contact with the inside surface of the shells 323. The regeneration liquid waste flowing down along the inside surface of the shell 323 is pressed onto the inside surface of the shell 323 by the centrifugal force caused by the movement of the pivotally rotatable blades 325 in the direction of arrow 363. On the other hand, steam under 7 atmospheres is supplied into an annular space formed by the shell 323 and the jacket 339 from the heating medium inlet 340. The steam flows from the heating medium outlet 341. The wall surface of the shell 323 surrounded by the jacket 339 is heated by the steam. The wall surface is a heat transfer surface 342. While the regeneration liquid waste flows down along the heat transfer surface 342, water is evaporated from the regeneration liquid waste. The resulting water vapor flows from the vapor outlet 333 through the vapor chamber 338. Sodium sulfate in the regeneration liquid waste is deposited while the water is evaporated from the regeneration liquid waste, and made into powder by the action of rotating pivotally rotatable blades 325. Sodium sulfate and NH.sub.2 (CH.sub.2).sub.2 NH(CH.sub.2).sub.3 Si(OCH.sub.3).sub.3 undergo a condensation reaction in the thin film drier 12, particularly at its lower part, and chemical bond each other. The powder of sodium sulfate bonded to NH.sub.2 (CH.sub.2).sub.2 NH(CH.sub.2).sub.3 Si(OCH.sub.3).sub.3 is taken out of the thin film drier 22 from the powder outlet 335. The powder is led to the powder hopper 45 through the conduit 43. Water content of the powder in the powder hopper 45 is measured by the moisture meter 46. If the moisture content of the powder is below the set value, the three-way valve 49 is operated by the function of the controller 47, whereby the powder hopper 45 is connected to the pelletizer 53. The powder in the powder hopper 45 is supplied into the hopper 561 of the pelletizer 53 through the conduit 48. The screw feeder 562 in the hopper 561 is rotated to feed the powder in the hopper 561 into between a pair of the rolls 555 and 557, which are rotated individually by the driving of motors. The rolls 555 and 557 rotate so that the recesses 556 and 558 on the peripheral surfaces of the individual rolls can face each other. The powders supplied by the screw feeder 562 is supplied to the recesses 556 and 558. When the recesses 556 and 558 come to each other most closely by the rotation of the individual rolls, that is, when the recesses 556 and 558 face each other, the powder is compressed most compactly. Almond-shaped pellets 566 are shaped by said pelletizing action. Sodium sulfate in the pellets 566 forms a cross-linked structure, as shown by C of FIG. 1. The amount of NH.sub.2 (CH.sub.2).sub.2 NH(CH.sub.2).sub.3 Si(OCH.sub.3).sub.3 in the pellets 566 is 2% by weight. The pellets 566 fall into the pellet hopper 55 through the conduit 54. When the water content of the powder in the powder hopper 45 is higher than the set value, the three-way valve 49 is operated by the controller 47, whereby the conduit 48 is connected to the conduit 50. Naturally, the operation of the thin film drier 22 is discontinued. The powder having a higher water content than the set value is dissolved in washing water supplied into the powder hopper 45, and discharged into the tank 51 through the conduit 50 without being fed to the pelletizer 53. The solution of sodium sulfate in the tank 51 is returned to the tank 1 through the conduit 52, and retreated. After the powder has been discharged from the powder hopper 45, the inside of the powder hopper 45, etc. is dried, and then the thin film drier 22 is restarted. The pellets 566 in the pellet hopper 55 are supplied onto the belt conveyor 57 through the conduit 56, and the belt conveyor 57 transports the pellets 566 to the pellet chute 59 of the storage tank 58. The pellets 566 are placed into the storage tank 58 from the pellet chute 59, and stored in the storage tank 58 for a definite period until the ratioactivity is decayed. The pellets 566 whose radioactivity has been decayed to a desired value is discharged from the storage tank 58 by suction through the pellet suction conduit 60 by driving the blower 61, and filled into the drum 62. Asphalt is poured into the drum 62 filled with the pellets 566, and the drum 62 is tightly sealed after the solidification of asphalt. Characteristics of the pellets 566 shaped according to the present invention are shown in FIGS. 6, 7 and 8, where a curve L shows the characteristics of conventional pellets containing no binder, a curve M shows the characteristics of pellets obtained by adding NH.sub.2 (CH.sub.2).sub.2 NH(CH.sub.2).sub.3 Si(OCH.sub.3).sub.3, silane coupling agent, as a binder according to the present invention, and a curve N shows the characteristics of pellets obtained by adding NH.sub.2 (CH.sub.2).sub.2 NH(CH.sub.2).sub.3 Si(OCH.sub.3).sub.3 and SiO.sub.(2-x) (ONa).sub.x/2 (OH).sub.x/2, colloidal silica, as binders according to the present invention, as will be described later. The content of the binder in the pellets is 2% by weight. Description will be made from FIG. 7. FIG. 6 shows changes in the water content of the individual pellets when the pellets are maintained in the atmospheres of the individual relative humidities for 400 hours. As is obvious from the comparison of the curve L with the curve M, the water content of the pellets obtained by adding the silane coupling agent according to the present invention is considerably lower even in the atmosphere of 100% relative humidity than that of the conventional pellets containing no binder. The hygroscopicity of the pellets according to the present invention is considerably low, and the deliquescence can be prevented. Furthermore, when the pellets prepared according to the present invention are stored in a storage tank as described in U.S. patent application Ser. No. 55,151 for a long period of time, conditions for controlling the pellets can be made milder. FIG. 7 shows relations between the fall distance and the percent fall breakage of pellets. The percent fall breakage of the pellets obtained by adding the silane coupling agent according to the present invention is considerably lower than that of the conventional pellets containing no binder. For example, at a fall distance of 15 m, the latter is 100% broken, whereas the former is only about 25% broken. FIG. 8 shows relations between the Fe.sub.2 O.sub.3 content of pellets and percent pellet breakage at a fall distance of 10 m. Curves L and M show an increasing tendency of percent pellet breakage with increasing Fe.sub.2 O.sub.3 content, but the increasing tendency of the percent breakage of the pellets according to the present invention with increasing Fe.sub.2 O.sub.3 content is considerably lower than that of the conventional pellets containing no binder, and the percent breakage itself of pellets according to the present invention is considerably low. The addition of a binder means an increase of pellet volume, and is not preferable from the viewpoint of reducing the volume of radioactive waste, as described above. However, in the case of adding 2% by weight of a binder as in the foregoing example of the present invention, a density is increased, but a volume is hardly increased, as shown in the following Table 1, and thus the addition of a binder gives no adverse effect upon the volume reduction ratio. TABLE 1 ______________________________________ Pellets contain- Pellets contain- ing binder ing no binder ______________________________________ Amount of binder 2 0 added (% by weight) Density (g/cm.sup.3) 2.40 2.35 Weight (g/pellet) 9.0 8.8 ______________________________________ In the case of using a silane coupling agent having reactive groups that will be converted to hydroxyl group by hydrolysis when dissolved in water as described above, the hydroxyl groups attached to the surface of sodium sulfate and the hydroxyl groups formed by the hydrolysis of said reactive groups undergo dehydrating condensation reaction in the drying step and evaporate as water, and thus the amount of the silane coupling agent in the pellets is decreased correspondingly. Thus, in the case of using the silane coupling agent having the reactive groups that will be converted to the hydroxyl groups by hydrolysis, the effect upon the volume reduction ratio is much less than the cases of using other silane coupling agents. In the foregoing example of the present invention, N-.beta.-(aminoethyl)-.gamma.-aminopropyltrimethoxysilane [NH.sub.2 (CH.sub.2).sub.2 NH(CH.sub.2).sub.3 Si(OCH.sub.3).sub.3 ], a silane coupling agent having an amino group, is used as the binder, but other silane coupling agents such as vinyltrichlorosilane [CH.sub.2 .dbd.CHSiCl.sub.3 ], vinyl-tris-(.beta.-methoxyethoxy)-silane [CH.sub.2 .dbd.CHSi(OCH.sub.2 H.sub.4 OCH.sub.3).sub.3 ], .gamma.-mercaptopropyltrimethoxysilane [HSC.sub.3 H.sub.6 Si(OCH.sub.3).sub.3 ], etc. are applicable with similar effects to that when NH.sub.2 (CH.sub.2).sub.2 NH(CH.sub.2).sub.3 Si(OCH.sub.3).sub.3 is used. However, in the case of water-insoluble silane coupling agents such as .gamma.-methacryloxypropyltrimethoxysilane ##STR1## etc., they must be dispersed into water by means of a surfactant. The addition of surfactant decreases the volume reduction of the radioactive liquid waste correspondingly. Among the silane coupling agents, the binding force (to sodium sulfate) of silane coupling agents having an amino group is strongest. As other binders than the silane coupling agent, inorganic binders such as aluminum phosphate, colloidal silica, etc., cellulose binders, emulsified teflon, etc. as shown in the following Table 2 are available, but have advantages and disadvantages at the same time. In the case of adding an emulsion to the regeneration liquid waste, a surfactant must be added. TABLE 2 ______________________________________ Comparison of binders Applica- Percent* Percent** tion breakage water ab- Binder Example Property (%) sorption ______________________________________ None -- -- 21 5 Aluminum Brick Water- 1 10 phosphate soluble cellulose Fertilizer Emulsion 15 3 teflon water-proof " 20 0.1 fabric silane coupl- Reinforced Water- 3 2 ing agent plastic soluble ______________________________________ Percent breakage at a fall distance of 6 m when 2% by weight of the respective binder was added. *Humidty: 90%, time for being left standing: 400 hours In the foregoing example of the present invention, the regeneration liquid waste containing sodium sulfate is treated, but radioactive liquid wastes in a slurry state such as granular ion exchange, powdery resin, cellulose powder, etc. can be also treated with the similar effect. Particularly, the functional group of the silane coupling agent is generally very reactive with the resins such as plastics, etc., and thus has a considerable effect. As one example of the effect, the influence of ion exchange resin is shown in FIG. 10, where a case of mixing the regeneration liquid waste containing sodium sulfate as a main component with used granular ion exchange resin is exemplified. The granular ion exchange resin can be also made into powder by the thin film drier. Curve M shows the characteristic of pellets containing 2% by weight of NH.sub.2 (CH.sub.2).sub.2 NH(CH.sub.2).sub.3 Si(OCH.sub.3).sub.3 as a silane coupling agent. It is obvious from FIG. 10, the percent breakage of the pellets according to the present invention is considerably lower in the case of treating the granular ion exchange resin according to the present invention than that of the conventional pellets containing no binder, as shown by curve L. The hygroscopicity of the pellets according to the present invention is also considerably low. However, when the ratio of the powder of granular ion exchange resin is increased, there is an increasing tendency of the percent breakage of the formed pellets. In the foregoing example, 2% by weight of the binder is selected as an optimum amount to be added, as shown in FIG. 5, but the optimum amount generally depends upon the physical properties of solid matters. The larger the amount of inorganic substances contained, the larger the amount of a binder to be added. It is natural to add a larger amount of the binder to form stronger pellets, but as a result the amount of the waste is disadvantageously increased. An example according to FIG. 11 will be described below. A mixture of a silane coupling agent NH.sub.2 (CH.sub.2).sub.2 NH(CH.sub.2).sub.3 Si(OCH.sub.3).sub.3 and colloidal silica SiO.sub.(2-x) (ONa).sub.x/2 (OH).sub.x/2 at a mixing ratio of the colloidal silica to the silicone coupling agent of 0.1-1 by weight is used as a binder. The binder is supplied in a state of aqueous solution from the tank 14 in FIG. 1 into the mixing tank 12 to be mixed with the regeneration liquid waste 2 containing sodium sulfate as a main component in the same manner as in the foregoing example. Successive treatment is carried out in the same manner as shown in FIG. 1. The characteristics of the pellets obtained according to the present example are shown by the curve N in FIGS. 6 and 7. As is evident from FIGS. 6 and 7, the hygroscopicity of the pellets is further lowered and the strength is considerably increased in the case of using the mixture of the silane coupling agent and the colloidal silica as the binder, as compared with the case of using the silane coupling agent only as the binder. According to another embodiment of the present invention, a silane coupling agent, colloidal silica, and methyl siliconate [CH.sub.3 Si(ONa).sub.3 ] of organosilicon group, which is alkyl silanol, as a third component are used as the binder. Methyl siliconate is mixed into the mixture of the silane coupling agent and the colloidal silica at a mixing ratio of the methyl siliconate to the mixture of 0.1-1. The binder is supplied into the mixing tank 10 of FIG. 12 to be mixed with the regeneration liquid waste containing sodium sulfate as a main component. Successive treatment is carried out in the same manner as in FIG. 2. Characteristics of the pellets obtained according to the present example are shown in FIG. 10, where the pellets are maintained in the atmosphere of 100% relative humidity for 400 hours. It is obvious from FIG. 12 that the hygroscopicity of the pellets is considerably lowered. The present invention is also applicable to the treatment of a liquid waste containing sodium borate (Na.sub.2 B.sub.4 O.sub.7) produced from other type of nuclear power plants such as a pressurized water type nuclear power plant, etc., or to the treatment of a liquid waste containing sodium nitrate (NaNO.sub.3) as a main component, produced from a nuclear fuel reprocessing plant. When these liquid wastes containing the silane coupling agent are made into powder, and when the resulting powder is pelletized, the pellets have almost same characteristics as those of the pellets obtained when the liquid waste containing sodium sulfate as a main component is treated. According to the present invention, the hygroscopicity of the pellets is considerably lowered.
	abstract	A core of a light water reactor has a plurality of fuel assemblies. The fuel assemblies include a plurality of fuel rods in which a lower end is supported by a lower tie-plate and an upper end is supported by an upper tie-plate. The fuel rods form plenums above a nuclear fuel material zone and have a neutron absorbing material filling zone under the nuclear fuel material zone. Neutron absorbing members attached to the upper tie-plate are disposed between mutual plenums of the neighboring fuel rods above the nuclear fuel material zone. The neutron absorbing members have a length of 500 mm and are positioned at a distance of 300 mm from the nuclear fuel material zone. Even if the overall core is assumed to become a state of 100% void, no positive reactivity is inserted to the core.
	description	Embodiments of the present invention are described in detail hereinafter with reference to the accompanying drawings. (Embodiment 1) A fuel assembly according to the first embodiment of the present invention is described with reference to FIGS. 1 and 2. The fuel assembly of this embodiment is loaded into a reactor core wherein a water gap width on a control rod side (control rod-side water gap width) and that on a side opposite to the control rod side (opposite-side water gap width) are almost equal to each other. FIG. 1 is a cross sectional view of the fuel assembly and FIG. 2 is a schematic longitudinal sectional view thereof. As shown in FIG. 2, the fuel assembly has a fuel bundle (without a symbol), an upper tie plate 14, a lower tie plate 15 and a channel box 13. The fuel bundle has a plurality of fuel rods 10, one water rod 21 (not shown in FIG. 1) and a plurality of spacers 16. The channel box 13 has a square pipe shape and covers the fuel bundle from the outside. The upper tie plate 14 and the lower tie plate 15 hold upper end portions and lower end portions of the fuel rods 10, respectively. The spacers 16 are disposed axially at predetermined certain intervals for holding spaces between the fuel rods 10. As shown in FIG. 1, ninety-one fuel rods 10 are arranged in a square lattice of 10 rows by 10 columns (10xc3x9710) and one water rod 21 of a square pipe shape is disposed in a central region of 3 rows by 3 columns (3xc3x973). Nine fuel rods 10 can be disposed in this central region. Each fuel rod 10 has a zircalloy clad tube packed with nuclear fuel pellets formed by a dioxide of enriched uranium. As shown in FIG. 1, if the fuel assembly is divided into a control rod side and a side (anti-control rod side) opposite to the control rod side by a diagonal line 13a, the water rod 21 is shifted toward the control rod side. In other words, a center of the water rod 21 is shifted toward the one where the control rod 24 is inserted, away from a cross sectional center of the fuel assembly. As shown in FIG. 2, the channel box 13 is fixed to the fuel bundle by fixing a channel fastener 17 to a corner post 18 that is attached to the upper tie plate 14 at the one corner where the control rod 24 is inserted. Thus, the aforementioned control rod side corresponds to the channel fastener side or the corner post side. In this embodiment, since the water rod 21 is shifted toward the control rod side (channel fastener side, corner post side), thermal neutron flux near the control rod 24 increases and hence it is possible to enhance the control rod worth. Therefore, in comparison with a case where the water rod is disposed at the center of the fuel assembly or shifted toward a side opposite the control rod side, the reactor shutdown margin can be increased while attaining higher burnup of the fuel assembly. As a result, it is possible to improve the fuel economy and decrease the amount of spent fuel. (Embodiment 2) A fuel assembly according to the second embodiment of the present invention is described with reference to FIG. 3. FIG. 3 is a cross sectional view of the fuel assembly. This second embodiment is different from the first embodiment in that two types of fuel rods are used that have different active fuel lengths. The active fuel length is the length of the portion of the fuel rod packed with nuclear fuel pellets. More specifically, one type of fuel rod is a long-length (full-length) fuel rod 11 having a relatively large active fuel length and the other type of fuel rod is a short-length (part-length) fuel rod 12 having an active fuel length about 15/24 that of the long-length fuel rod 11. As shown in FIG. 3, eight short-length fuel rods 12 are disposed in the second layer from the outside of the fuel assembly. One of them is disposed on the control rod side and five are disposed on the side opposite to the anti-control rod side. In this embodiment, it is possible to increase the reactor shut-down margin as in the first embodiment. In addition, this embodiment attains the following effect. The short-length fuel rods generally contribute to a flattening of the moderator (water) distribution in an axial direction of the fuel assembly. In this embodiment, since the short-length fuel rods 12 are disposed in a larger number on the side opposite to the control rod side than on the control rod side, it is also possible to flatten the moderator distribution in a cross section of the fuel assembly. These effects contribute to flattening of the local power distribution and to a decrease in the rise of reactivity when the reactor is in a cold shut-down condition. As a result, the thermal margin can be increased. (Embodiment 3) A fuel assembly according to the third embodiment of the present invention is described with reference to FIG. 4. FIG. 4 is a cross sectional view of the fuel assembly. In this embodiment, short-length fuel rods 12, arranged separately in the second embodiment, are concentrated around a water rod 21 of a square pipe shape. More specifically, seven short-length fuel rods 12 are disposed at positions adjacent to the water rod 21 on the side opposite to the control rod side. Five of the short-length fuel rods 12 are disposed in a half area on the side opposite to the control rod side with respect to the diagonal line 13a. In this embodiment, an increase in the reactor shut-down margin and an increase in the thermal margin by flattening the local power distribution can also be attained as in the second embodiment. In addition, in this embodiment, a satisfactory moderation of neutrons is attained independently of the void fraction of the water (moderator) in the channel box 13 like a case that a cross sectional area of the water rod 21 increases effectively. Therefore, it is also possible to decrease an absolute value of the void coefficient. (Embodiment 4) A fuel assembly according to the fourth embodiment of the present invention is described with reference to FIG. 5. FIG. 5 is a cross sectional view of the fuel assembly. In this embodiment, which is a modification of the second embodiment, a certain improvement is made with respect to distribution of an average uranium enrichment (hereinafter referred to simply as xe2x80x9cenrichmentxe2x80x9d) of the fuel rods. More specifically, four types of long-length fuel rods with different enrichment are used, which include a fuel rod 1 of about 5 wt % (highest) enrichment, a fuel rod 2 of about 4 wt % enrichment, a fuel rod 3 of about 3 wt % enrichment, and a fuel rod 4 of about 2 wt % (lowest) enrichment. A fuel rod 1a can be the same short-length fuel rod as in the second embodiment and its enrichment is about 5 wt % (highest). Other constructional points are the same as in the second embodiment and therefore explanations thereof are omitted here. As shown in FIG. 5, the fuel rods 4 of the lowest enrichment are disposed at four corners of the outermost layer and the fuel rods 3 of the second lowest enrichment are disposed at positions close to the corners in the outermost layer. Fuel rods 2 of the second highest enrichment are disposed at positions adjacent to the water rod 21 in the row or column direction (vertical or transverse direction in FIG. 5). Further, fuel rods 1 of the highest enrichment are disposed at positions adjacent obliquely to the water rod 21. In a cross section perpendicular to an axis of the fuel assembly, the average enrichment of the fuel rods in one half area (hereinafter referred to as xe2x80x9copposite the control rod side areaxe2x80x9d) on the opposite the control rod side that is divided by the diagonal line 13a is higher than that of the fuel rods in the other half area (hereinafter referred to as the xe2x80x9ccontrol rod side areaxe2x80x9d) on the control rod side. In this embodiment, the same effect as in the second embodiment can be obtained. In addition, in this embodiment, since the average enrichment in the opposite to the control rod side area, where thermal neutron flux is relatively low, is set higher than that in said the control rod side area, the local power distribution can be flattened more effectively. (Embodiment 5) A fuel assembly according to the fifth embodiment of the present invention is described with reference to FIG. 6. FIG. 6 is a cross sectional view of the fuel assembly. In this embodiment, which is a modification of the fourth embodiment, a certain improvement is made with respect to an arrangement of gadolinia-filled fuel rods (hereinafter called xe2x80x9cGd fuel rodsxe2x80x9d). Gadolinia is one of burnable absorber. The Gd fuel rod 9 has an average uranium enrichment of about 4 wt % and an average gadolinia concentration of about 5 wt %. Sixteen Gd fuel rods 9 are arranged in the fuel assembly. Ten of them are disposed in the anti-control rod side area and six are disposed in the control rod side area. In the second layer from the outside of the fuel assembly, the Gd fuel rods 9 are disposed at eight positions adjacent to the fuel rods 1a (the short-length fuel rods of the highest enrichment) located at corner positions. Other constructional points are the same as in the second embodiment and therefore explanations thereof are omitted here. This embodiment also brings about the same effect as in the fourth embodiment. In addition, in this embodiment, since the Gd fuel rods are disposed in a larger number in the opposite the control rod side area, a larger number of neutrons are absorbed in the opposite the control rod side area than in the control rod side area. As a result, the thermal neutron flux in the control rod side area can be increased relatively and hence it is possible to enhance the control rod worth and increase the reactor shut-down margin in comparison with the fourth embodiment. (Embodiment 6) A fuel assembly according to the sixth embodiment of the present invention is described with reference to FIG. 7. FIG. 7 is a cross sectional view of the fuel assembly. In this embodiment, one cylindrical water rod 22 is disposed in the 33 central region instead of the water rod 21 in the third embodiment shown in FIG. 4. A cross sectional area of the water rod 22 is smaller than that of the water rod 21. Other constructional points are the same as in the third embodiment and therefore explanations thereof are omitted here. This embodiment also brings about the same effect as in the third embodiment. In addition, in this embodiment, since the cross sectional area of the water rod is set smaller than that in the third embodiment, wasteful absorption of neutrons by the water rod when the reactor is in a hot operating condition can be reduced. Therefore, it is possible to improve the neutron economy more than in the third embodiment. (Embodiment 7) A fuel assembly according to the seventh embodiment of the present invention is described with reference to FIG. 8. FIG. 8 is a cross sectional view of the fuel assembly. In this embodiment, which is a modification of the first embodiment shown in FIG. 1, the number of fuel rods is increased for the purpose of attaining higher burnup than in the first embodiment. That is, one hundred and five fuel rods 11 are arranged in a square lattice of 11 rows by 11 columns (11xc3x9711) and one water rod 23 of a square pipe shape is disposed in a central region of 4 rows by 4 columns (4xc3x974). Sixteen fuel rods can be disposed in this central region. As shown in FIG. 8, if the fuel assembly is divided into the control rod side and the opposite the control rod, the water rod 23 is shifted toward the control rod side. Therefore, this embodiment also brings about the same effect as in the first embodiment. Although one water rod is used in the above embodiments, there also may be used a plurality of water rods. In this case, if the water rods are shifted toward one corner where a control rod is inserted from a cross sectional center of the fuel assembly, the same effects as in the above embodiments can be obtained. Further, although enriched uranium is used as the nuclear fuel in the above embodiments, there also may be used a nuclear fuel obtained by replacing a portion or the whole of enriched uranium with plutonium-enriched uranium. In this case, the same effects as in the above embodiments can be obtained.
	description	The present invention concerns a fuel assembly for a nuclear boiling water reactor, wherein the reactor comprises a plurality of such fuel assemblies, and a plurality of control rods, each control rod being insertable in a respective control rod position between the fuel assemblies, wherein the fuel assembly has a longitudinal center axis and includes a plurality of elongated fuel rods, each fuel rod comprising nuclear fuel enclosed by a cladding, the fuel rods being held in predetermined positions relative one another with the help of a number of spacer grids, and an elongated channel box forming an outer casing of the fuel assembly and enclosing the fuel rods, the channel box having inner sides, facing the fuel rods, and outer sides, each inner side and each outer side having a longitudinal center line extending in parallel with the center axis and along the length of the channel box, wherein a number of protrusions are provided on the channel box to protrude from at least two of the outer sides. The above described fuel assemblies and control rods are positioned in the core of the nuclear boiling water reactor (nuclear BWR). The channel boxes of the fuel assemblies in the nuclear BWR usually consist of a corrosion resistant material with a low neutron absorption capacity, such as a zirconium based alloy. The environment in the core of a nuclear BWR is demanding for the components positioned therein. The environment is for example highly oxidative. One of the consequences of this demanding environment inside the core of a nuclear BWR is that the channel box of the fuel assemblies may be distorted. The channel box may for example bulge or bow. Channel box bow is due to elongation of one channel box side relative the opposite channel box side. Channel box bow is known to arise for different reasons, e.g. initial manufacturing, residual stress relaxation under irradiation, differential irradiation growth and shadow corrosion. The problem of shadow corrosion on components comprising zirconium based alloys in the core of a nuclear BWR has been known for a long time. Shadow corrosion is a local corrosion enhancement and can appear on a zirconium based alloy component when the component is in close contact with another metal. Referring to the above, shadow corrosion on the outer side of a channel box can occur when a control rod blade is inserted next to the channel box, i.e. when the channel box consisting of a zirconium based alloy is in close contact with a control rod blade usually having an outer surface of stainless steel. Shadow corrosion early in the life of a fuel assembly, i.e. shadow corrosion on the fuel assembly due to an inserted control rod next to the fuel assembly during the first several months of operation, is generally believed to drive the problem of enhanced channel bow of the channel boxes in a nuclear BWR. The shadow corrosion can result in increased absorbed hydrogen-induced growth of the outer side of the channel box being closest to the control rod. The increased absorbed hydrogen-induced growth can lead to bowing of the channel box towards the control rod late in the life of the fuel assembly. The bow of the channel box towards the control rod may lead to channel box-control rod interference, which may for example cause the fuel assemblies to lift due to friction when the control rods are inserted into the core. Studies have shown that shadow corrosion strongly depends on the distance between the zirconium based alloy component and the component comprising another metal. The occurrence of shadow corrosion is therefore most significant in the case of a large control rod blade and a small distance between the control rod blade and the channel box. JP 05-323069 discloses a channel box for a nuclear BWR, wherein the channel box has axially projecting pads on the outer sides of the channel box. The projecting pads are provided on the two outer sides of the channel box that faces a control rod when the control rod is inserted into the core of the reactor. The object of the projecting pads is to ensure a gap between the fuel assemblies, where the control rod is to be inserted, even if the channel box is deformed by channel box bowing against the control rod. The bowing of the channel box is described to be caused by elongation of the channel box due to exposure to neutrons during operation. Accordingly, even if the channel box would bow towards the control rod, the projecting pads on the outer sides of the channel box will ensure that it is possible to insert a control rod between the fuel assemblies. One object of the present invention is to mitigate shadow corrosion on the channel box of a fuel assembly of a nuclear BWR, thereby reducing the risk of shadow corrosion enhanced channel box bow. The present invention resides in one aspect in a fuel assembly that includes protrusions distributed along the center line of the at least two outer sides, wherein the protrusions are configured to ensure a minimum distance between the outer side and an adjacent control rod, and to enable the control rod to easily slide over and on top of the protrusions. The design of the fuel assembly according to the invention thereby prevents a control rod blade from coming too close to the channel box of the fuel assembly. Moreover, the design of the protrusions ensures a smooth insertion of the control rod between the fuel assemblies, preventing the control rod from being damaged. According to an embodiment, the protrusions are distributed along the full length, or substantially the full length, of the outer sides of the channel box. By distributing the protrusions along substantially the full length of the outer sides, a smoother insertion of the control rod between the fuel assemblies can be achieved. Moreover, the action of mitigating shadow corrosion on the outer sides of the channel box will be more uniform over the outer sides when the protrusions are provided and distributed along substantially the full length of the outer sides. According to an embodiment, the protrusions are distributed along the center line of each of the outer sides of the channel box. By providing protrusions on each of the outer sides of the channel box, the manufacturing of the box is facilitated and possible manufacturing problems are reduced. Furthermore, non-symmetric formation of shadow corrosion on the outer sides of the channel box may be prevented. According to an embodiment, the protrusions protrude 0.5-1.5 mm, preferably 0.8-1.2 mm, from the outer sides of the channel box. Studies have shown that an increase of the distance between the control rod and the channel box from for example 0.4 mm to 1.0 mm can mitigate the shadow corrosion on the channel box by more than a factor of 2. According to an embodiment, the protrusions are distributed at a distance of at least 50 mm from each other. According to an embodiment, the protrusions are distributed at a distance of most 1000 mm from each other. For example, the protrusions may be distributed at a distance of 80-120 mm, such as 100 mm, from each other. According to an embodiment, the protrusions are evenly distributed along the center line of the outer sides of the channel box Preferably, the protrusions are distributed at equal distances from each other along the center line of the outer sides. According to an embodiment, the protrusions have a curved shape, the curved shape facilitating the sliding of a control rod blade of the control rod over and on top of the protrusions. According to an embodiment, the channel box comprises four walls extending in parallel with the center axis, the walls comprising said inner sides and said outer sides, respectively. According to an embodiment, the channel box has a substantially square cross section seen in the direction of the center axis. According to an embodiment, the fuel assembly further comprises an elongated support member extending in the direction of the center axis, the support member having a cruciform cross section seen in the direction of the center axis, wherein the support member is secured to the inner sides of the channel box through a plurality of weld joints along the center lines. The support and/or rigidity given to the fuel assembly by the support member substantially reduce stresses and deformations. The construction of a fuel assembly including a support member thereby permits a significant reduction in the thickness of the channel box walls. According to an embodiment, the support member comprises four wings, each wing being secured to a respective inner side of the channel box. According to an embodiment, the support member divides the fuel rods of the fuel assembly into four equal sub-groups. According to an embodiment, the support member is hollow, forming a vertical channel through which water can flow upwardly through the fuel assembly. An embodiment of a nuclear boiling water reactor which can comprise the fuel assembly according to the invention will first be described with reference to FIG. 1. FIG. 1 shows part of a nuclear plant. The nuclear plant comprises a reactor 1. The reactor 1 comprises a core 2 having a plurality of fuel assemblies 3. Each fuel assembly 3 has a longitudinal center axis z, see FIG. 3. Furthermore, each fuel assembly 3 includes a plurality of elongated fuel rods 7, see FIG. 3. Each fuel rod 7 comprises nuclear fuel 7a and a cladding 7b enclosing the nuclear fuel 7a. The fuel rods 7 are held in predetermined positions relative one another with the help of a number of spacer grids, not shown. The reactor 1 further comprises a plurality of control rods 4 schematically indicated in FIG. 1. The control rods 4 are located between the fuel assemblies 3 and are connected to drive members 5. Each control rod 4 has four control rod blades 4a, see FIG. 3, disposed in a cruciform arrangement. The drive members 5 are able to move the control rods 4 up and down in a vertical direction x into and out from a respective position between the fuel assemblies 3. An embodiment of a fuel assembly according to the invention will now be described with reference to FIG. 2 and FIG. 3. FIG. 2 and FIG. 3 show a fuel assembly 3 comprising an elongated channel box 6. The channel box 6 forms an outer casing of the fuel assembly 3 and has a square, or substantially square, cross section seen in the direction of the center axis z. The channel box 6 encloses a plurality of elongated fuel rods 7. The channel box 6 comprises four walls. The walls extend in parallel with the center axis z. Furthermore, the channel box 6 has four inner sides 8 and four outer sides 9. Each wall of the channel box 6 comprises or forms a respective inner side 8 and a respective outer side 9. The inner sides 8 of the channel box 6 face the fuel rods 7. Each inner side 8 and each outer side 9 has a longitudinal center line y extending in parallel with the center axis z along the length of the channel box 6. The fuel assembly 3 further comprises an elongated support member 10 extending in the direction of the center axis z. The support member 10 has a cruciform cross section seen in the direction of the center axis z. The support member 10 is secured to the inner sides 8 of the channel box 6 via a plurality of weld joints 11 along the center lines y. In the embodiment according to FIG. 3, the support member 10 has four wings 10a. Each wing 10a is secured via the weld joints 11 to a respective inner side 8 of the channel box 6. Furthermore, the support member 10 has a center part 10b. In the present embodiment, the wings 10a and the center part 10b are hollow. However, the wings 10a and the center part 10b may also be solid. The hollow support member 10 of the present embodiment forms a vertical channel through which water can flow upwardly through the fuel assembly 3. Furthermore, the support member 10 divides the fuel rods 7 of the fuel assembly 3 into four equal sub-groups. Each sub-group has an approximately square cross section seen in the direction of the center axis z. A number of protrusions 12 are provided on the channel box 6 to protrude from at least two of the outer sides 9. As shown FIG. 4 the protrusions 12 are present on two of the outer sides 9. In one embodiment, shown in FIGS. 2 and 3 the protrusions are present on four of the outer sides 9. As shown in FIG. 2 there are a plurality of the protrusions 12 distributed along the center line y of the outer sides 9. The protrusions 12 are distributed along substantially the full length, or the full length, of the outer sides 9. Preferably, the protrusions 12 are distributed along the center line y of each of the outer sides 9 of the channel box 6. Moreover, the protrusions 12 are evenly distributed along the center line y. Preferably, the protrusions 12 are evenly distributed between the weld joints 11, as shown in FIG. 2, i.e. there may be a protrusion 12 between each pair of adjacent weld joints 11. The protrusions 12 are distributed at a distance d1 of at least 50 mm from each other and of most 1000 mm, 800 mm, 600 mm, 400 mm, 200 mm or less from each other. For example, the protrusions are distributed at a distance d1 of 100 mm from each other. The protrusions 12 are configured to ensure a minimum distance d2 between the outer side 9 and an adjacent control rod blade 4a. The protrusions 12 protrude a distance d2 of about 0.5-1.5 mm from the outer sides 9 of the channel box 6. Preferably, the protrusions 12 protrude 1.0 mm or slightly less, such as for example 0.8-1.2 mm, from the outer sides 9. Furthermore, the protrusions 12 are configured to enable a control rod 4 to easily slide over and on top of them. Preferably, the protrusions 12 have a curved shape at least when seen in a direction perpendicular to the center axis z of the channel box 6, see FIG. 2. The curved shape facilitates the sliding of the control rod 4 over and on top of the protrusions 12. The minimum distance d2 between the outer sides 9 of the channel box 6 and an inserted control 4 rod mitigates the phenomenon of shadow corrosion on the outer sides 9 of the channel box 6. The mitigation of shadow corrosion on the channel box 6 reduces the risk of channel box bow towards the control rod 4. Shadow corrosion may however occur on the protrusions 12, but then only locally. The present invention is not limited to the shown embodiments but can be varied and modified within the scope of the following claims.
	claims	1. A scintillator panel comprising:a glass substrate with a thickness of not more than 150 μm having radiotransparency;a first organic resin layer formed so as to cover the entire surface of the glass substrate;a scintillator layer formed on a one face side of the glass substrate on which the first organic resin layer is formed;a moisture-resistant protection layer formed so as to cover the scintillator layer along with the glass substrate on which the first organic resin layer is formed,wherein a resin film layer is stuck between an other face side of the glass substrate on which the first organic resin layer is formed, and the protection layer. 2. The scintillator panel according to claim 1, wherein the first organic resin layer is selected from poly-para-xylylen and polyurea. 3. The scintillator panel according to claim 1, wherein the resin film layer is selected from PET, PEN, COP, and PI. 4. A radiation detector comprising:the scintillator panel as set forth in claim 1; anda light receiving element arranged opposite to the scintillator layer on which the protection layer is formed.
	description	This application claims priority to U.S. Provisional Application No. 60/518,369, filed Nov. 7, 2003, which is incorporated herein by reference in its entirety. X-ray imaging is a valuable technology for non-destructive imaging applications in medicine and industrial research and development. All x-ray imaging systems include a source that generates the x-ray beam, which is used to probe the object to be examined, and a detector system for collecting the x-ray beam. The x-ray source is typically an electron-bombardment, a laser-plasma, or a synchrotron radiation source. The detector system is typically based on x-ray film or an electronic, such as charge-coupled device (CCD), detector. In some cases, an intervening scintillator is used to convert the x-ray radiation to a wavelength that is detectable by the detector device. Further, the x-ray beam is often modified by one or more beam-conditioning devices. Sometimes an energy filter, monochromator, or pinholes are place between the object or sample and the source. To focus the beam onto the sample a condenser lens, in the case of a full-field imaging microscope, or an objective lens, in the case of a scanning system, are typically used. The beam passing through the sample is then imaged to the detector by an objective lens, in the case of a full-field imaging microscope, or reaches the detector directly in the case of a scanning system. Most existing x-ray imaging systems, e.g. medical x-ray, airport x-ray scans, use the full spectrum of the x-ray emission, including the characteristic lines of the anode material and the Brehmstralung emissions. The resulting image is therefore an integrated intensity over the entire spectrum. A problem with this approach is that by using the entire spectrum, one looses an important attribute of x-ray imaging: the spectral sensitivity of various materials to x rays of different energies. As a result, the present invention is directed to the notion of using one or more emission lines of electron bombardment x-ray sources to selectively image certain materials with high sensitivity. Specific examples are provided that illustrate the imaging of semiconductor integrated circuit devices. The present invention is directed to using particular emission lines that are optimized for imaging specific metallic structures in a semiconductor integrated circuit structures and optimized for the use with specific optical elements and scintillator materials. Such a system is distinguished from currently-existing x-ray imaging systems that primarily use the integral of all emission lines and the broad Bremstralung radiation. The disclosed system provides favorable imaging characteristics such as the ability to enhance the contrast of certain materials in a sample, to use different contrast mechanisms in a single imaging system, and to increase the throughput of the system. A number of x-ray imaging systems are disclosed that utilize one or more atomic emission lines to image specific materials in a sample, taking advantage of the spectral absorption properties of the sample to produce high image contrast with appropriate imaging mechanisms. It also takes into account the response of optics and detectors at different x-ray energies. It deals, in particular, with materials used in current generation and next generation semiconductor integrated circuit devices. As an example, refer to FIG. 1, which shows the absorption spectrum of materials used most frequently in semiconductor devices: Copper, Aluminum, and Silicon. Typically copper or aluminum circuits are fabricated in a silicon substrate. To image the circuit structure, strong contrast is desirable between the circuit structure and the silicon substrate. The interaction of x-rays with most materials is complex and strongly dependent on the x-ray energy. A good example is illustrated in FIG. 1, where the 1/e attenuation length of silicon, aluminum, and copper is plotted as a function of x-ray energy, and shown along with the emission lines of tungsten and chromium. The absorption properties of these materials vary dramatically as a function of the x-ray energy. Therefore different material properties of the sample can be probed by varying the x-ray energy used to image a sample. For example, if the 1.8 keV x rays from tungsten M line is used to image an integrated circuit chip containing aluminum lines, the silicon substrate has relatively small attenuation while the aluminum lines will absorb strongly. Specifically, the aluminum line has an attenuation length of about 1 micrometer while silicon has an attenuation length of about 10 micrometers. The plot shows that absorption contrast between silicon and aluminum is strong only between their absorption edges: aluminum K-edge at 1560 electron-Volts (eV) and silicon K-edge at 1850 eV. There is little contrast between these materials at other energies above 1 keV. Therefore an imaging system that uses the entire emission spectrum of a target (emission lines plus the Brehmstralung radiation) will exhibit very low contrast between the aluminum structures and the silicon substrate. An imaging system using only the tungsten M line (1800 eV), however, will be able to take advantage of the intrinsic absorption difference between Al and Si to image Al structures with good contrast. The same considerations can be applied to imaging copper features as well. The absorption contrast between the copper lines and the silicon substrate is moderate at most energies but very strong between Cu L-edge at 1 keV and the silicon K-edge at 1.85 keV, and just above the Cu K-edge at 8.9 keV. To image Cu lines with high contrast, one should use x-ray energies within these two intervals. Two tungsten emission lines: Lβ at 9.7 keV and M line at 1.8 keV are well suited for this purpose. For one layer of a typical aluminum chip with 1 micrometer thickness, the aluminum transmits about exp(−1)=34% of the radiation while the silicon substrate transmits about exp(−0.1)=90%. This difference in the absorption properties allows for the imaging of the integrated circuits with strong elemental contrast and therefore clearly imaging the aluminum structures. In addition to imaging aluminum lines, the 1.8 keV emission from tungsten is also well suited for imaging copper lines in a integrated circuit chip since a similar absorption contrast exists between copper with 1/e attenuation length of 0.7 micrometers and silicon. In another example, a tungsten source is used to image copper or aluminum features in an integrated circuit chip. In this case, the 1.8 keV M-line is just below the silicon K absorption edge, but above the absorption edges of copper (Cu) (L line at 1 keV) and aluminum (Al) (K line at 1.5 keV). Therefore a sufficient absorption contrast is available between the Cu or Al structures and a silicon substrate, thereby allowing the imaging of Cu or Al lines in an integrated circuit chip. In other examples, Cu or Al structures are imaged on dielectric substrates. Some examples of dielectrics include: 1st Generation with 2.8≦k≦3.5: fluorinated-oxide film, also referred to as fluorinated silica glass (FSG) used for 0.25-0.5 um technology; 2nd Generation with 2.5≦k≦2.8: poly(alylene) ethers (PAE); and ultralow k dielectrics with k<2.0: nanoporous silica (SiO2) xerogel materials. Currently existing x-ray imaging systems typically use the full spectrum of the x-ray emission, including all the characteristic lines of the anode material and the Brehmstralung emission. These systems are therefore not able to take advantage of the energy-dependent x-ray imaging possibilities. It would be very difficult to image aluminum structures with these systems since the material contrast is only strongly exhibited near the absorption edge while the x-ray emission far from the edge does not produce strong image contrast between the aluminum features and the silicon substrate, therefore diluting the image contrast. In practice the attenuation length of the silicon (10 micrometers) requires the IC sample to be thinned to about similar thickness to obtain sufficient transmission. If the tungsten Lb emission (9.7 keV) line is used instead, the silicon attenuation length becomes 120 micrometers. Consequently, a sample thickness of over 100 micrometers can be tolerated. At this energy the attenuation length of copper becomes about 5 micrometers, and a strong absorption contrast still exists between the copper lines and silicon substrate. In comparison, the 1.8 keV emission is better suited for imaging fine feature since the 0.5 micrometers provides very high sensitivity, while the 9.7 keV x ray is better suited for imaging complex circuit structures in intact integrated circuit (IC) dies because the larger 5 micrometers attenuation length allows the penetration of a thick stack of copper line structures while maintaining high contrast against the silicon substrate. The long attenuation length in silicon also eliminates the need to thin the IC sample and thus simplifies the sample preparation process. For chips with very complex copper structures, the integrated copper thickness may exceed 10 micrometers. This thickness may be too opaque for the 9.7 keV x-ray. In this case the tungsten Lα line (8.4 keV) may be used. Since it is just below the copper absorption edge, it has relatively large attenuation length of about 15 micrometers. At this energy, however, the absorption contrast between copper and silicon substrate is reduced. A suitable phase contrast imaging method, such as a Zernike configuration (FIG. 2) or differential phase contrast methods can be used to boost the contrast of the copper features, especially the features with small lateral and thickness dimensions. Specifically, in FIG. 2, a condenser 210 is used to concentrate X-ray radiation on a sample or object 10. An objective lens 214 is used to collect the radiation after interaction with the sample 10. A phase ring 216 is used to create a relative phase shift between the diffracted and undiffracted radiation to create the phase contrast image 218. Depending on the implementation, the condenser lens 210 may include refractive optics, reflective optics, diffractive optics. The objective lens 214 includes Fresnel zone plates, reflective mirrors lens, refractive lens, or achromatic Fresnel optics. Both tungsten L and M are well suited to image IC chips with copper structures, but with different properties. An imaging system using a tungsten x-ray source that is able to utilize all L and M lines is able to satisfy a wide range of applications for imaging IC circuits. These may include failure analysis, process development and reverse engineering. Another consideration in imaging is that the materials must be sufficiently transmissive to allow sufficient light or radiation to penetrate the sample to be detected. In the previous example with Cu lines, the attenuation length for Cu is 0.5 micrometers at 1.8 keV and 6 micrometers at 9.7 keV. These dimensions are good for detecting small features, but a modern integrated circuit chip may contain up to 7 or 8 layers of copper structures with integrated thickness exceeding 10 micrometers. Such structures may not permit sufficient transmission for detection at these two energies, but the W Lα line at 8.4 keV is just below the Cu K-edge and has an attenuation length of about 30 micrometers. This allows the imaging of Cu structures of large integrated thickness, but with reduced imaging contrast. The contrast can be improved by using phase contrast techniques. The phase contrast depends on the relative mass density of materials in the sample. It is therefore relatively uniform through the energy spectrum, except for some abrupt changes near absorption edges. The Zernike phase contrast imaging method shown in FIG. 2 is commonly used in light microscopy and can be applied in x-ray imaging. Here, a ring condenser, instead of a full condenser used in bright-field imaging, projects radiation to the object. A phase ring is placed in the back focal plane. The shape of this phase ring is the image of the condenser formed by the objective lens. In this scheme, the direct radiation imaged by the objective is phase shifted by the phase ring while the radiation scattered by the object is unaffected by the phase ring (except for a small portion that passes the phase ring). These two beams interfere at the image plane to produce a phase-contrast image. With this method, ten-fold increase in contrast can be gained for Cu features at 8.4 keV compared with absorption contrast. One disadvantage of phase contrast imaging, however, is that the resulting imaging is not a linear map of some material properties of the sample, while using absorption contrast imaging, the resulting image is the integrated absorption map of the attenuation through the sample. Having a linear map makes the image easy to interpret and allows the use of a simple tomography algorithm to reconstruct the 3 D structure of the sample. The three dimensional tomography algorithm using phase contrast images is difficult. Phase contrast mechanism can be applied to image aluminum features in silicon substrates as well, as little absorption contrast exists between aluminum and silicon, except for a very narrow spectral band. Aluminum structures can be imaged with contrast gain of up to 20, at most energies, with Zernike phase contrast scheme. The spectral response of the optical components in an imaging system must also be considered. The optical train must be designed in an integrated approach. Note that, in comparison, no appreciable absorption contrast exists between Al and Si at energies above the silicon K-absorption edge. In addition to optimizing the x-ray energy for the best intrinsic contrast from the sample, one must also consider the effect on the optical train of the imaging system, most importantly the objective lens and the detector system. The highest resolution objective lens used in current x-ray imaging system are Fresnel zone plates. As shown in FIGS. 3a and 3b, the lenses are essentially circular diffraction gratings having concentric opaque or phase shifting rings arranged such that the radiation passing through them will arrive at the focal point in phase. Lens with opaque rings are called amplitude zone plates and the lenses with phase shifting rings are called phase zone plates. The resolution of a zone plate is approximately the outer zone width. It is clear from the geometric pictures in FIGS. 3a and 3b that the zone width becomes finer as the radius is increased. The challenge to producing high-resolution zone plate lenses is therefore the ability to make zone plates with finest outer zones. The other aspect of an objective lens is its efficiency. To obtain the highest efficiency, the opaque rings of an amplitude zone plate should completely absorb the radiation, while the rings in an ideal phase zone plate should shift the phase by n. With x rays, as the energy increases, both the attenuation length and the π phase shift length generally increases. Therefore, the zone plate must be made with increasing thickness. This increases the thickness to zone width ratio, or the aspect-ratio of a zone plate. Therefore, it is generally more challenging to fabricate zone plates for high energy x rays for the same outer zone width because of the higher aspect ratio that is required. Current fabrication techniques can provide objective lenses with about 25-30 nanometer resolution at Tungsten Mα line (1.8 keV) and about 70 nanometer resolution at Tungsten Lβ line (9.7 keV). An imaging system using the 1.8 keV x rays therefore provides better resolution in addition to the ten fold sensitivity for small features discussed above. Therefore having an imaging system that can utilize both emissions is more versatile than one using a single emission line, since a large sample can be imaged with the 9.7 keV emission while the 1.8 keV line can be used to image specific areas at high resolution. Material selection clearly plays an important role in obtaining high resolution and high efficiency zone plates. For x rays with a few keV energy, a phase shifting zone plate is preferred, and ideal materials for the zone plate should provide low absorption and large phase shifts and also should have desirable electrochemical properties, e.g. it should be easily electroplated into nano-structures that are free from grains. Currently, the preferred materials for zone plates for 1-3 keV x rays include rhodium (Rh), palladium (Pd), and silver (Ag), while the preferred material for 3-20 keV is gold (Au). As an example, FIGS. 4a and 4b show the efficiency as a function of energy for zone plates made from 500 nanometer thick Pd and 1 micrometer thick Au, respectively. In each case, efficiency of up to 25% to 30% can be achieved. The other important component of the optical train is the detector system. High-resolution full-field imaging systems typically employ scintillated charge-coupled device (CCD) camera systems. These types of detectors typically have a scintilator, some type of optical coupling, and a CCD camera. The highest resolution variants of this type of detectors use a grainless single crystal scintillator and high resolution visible-light microscope objective lens to image the light emitted from the scintillator to the CCD camera. The achievable resolution of the objective lens is related to the numerical aperture (NA) as: resolution=0.61λ/NA, where λ is the wavelength. The depth of field (DOF) from this objective can then be calculated as DOF=1.22λ/NA2. To achieve high resolution, a microscope objective lens with a large numerical aperture is required. For example, in order to achieve better than 1 micrometer resolution with a scintillator with 600 nanometer emission wavelength, an objective with a NA of about 0.4 is needed. The depth of field from this objective lens is roughly 4.5 micrometers. It is therefore desirable that the most of the x rays impinging on the scintillator are absorbed within this depth because light generated outside this depth range will not be collected effectively by the objective lens, but rather will contribute the background. The scintillator material must therefore be matched to the x-ray energy used. We list two specific examples. Two types of scintillators known with high efficiency are Cesium Iodine with Thallium doping and Lu2(1−x)Ce2x(SiO4)O or LSO. Their attenuation length is shown in FIG. 5. A very short attenuation length can be achieve by the following source and scintillator combinations: 1.8 keV W M-lineCsI or LSO5.4 keV Cr K-lineCsI or LSO8.4 keV W Lα lineCsI or LSO9.7 keV W Lβ lineLSO9.4 keV and 11.1 keV Pt L linesLSO9.7 keV and 11.4 keV Au L linesLSO At the 8.4 keV W Lα line, neither of the scintillators provides sufficient attenuation, but from above 9.5 keV, LSO provides very effective attenuation for the 9.7 keV W Lα line, as well as L lines from Pt or Au sources. CsI has about 25% to 50% higher efficiency per unit absorbed energy, so in cases where CsI and LSO have similar attenuation length, CsI is generally preferred because of the higher level of light output. On the other hand, CsI has a number undesirable material properties: it is highly hydroscopic and very soft. Consequently, its fabrication and maintenance is difficult. In contrast, LSO is a very robust material that can be easily fabricated and polished, with good long term stability. In addition to the systems described above that use a single atomic emission line for imaging specific materials, an x-ray imaging system can also utilize two or more emission lines to increase its versatility. For an example, a microscope for an imaging system could use all three emission lines of tungsten shown in FIG. 6 to image copper structures in a silicon substrate. Such a system uses the 8.4 keV line to image large scale structures, the 9.7 keV structure to obtain a linear absorption map of the sample or obtain its three dimensional structure, and the 1.8 keV line to study the fine features with extremely high sensitivity. An embodiment of such a system is shown in FIG. 7. An x-ray source 310 generates polychromatic radiation 312 with characteristic emission lines and the Brehmstralung radiation. In more detail, an x-ray beam 312 from a small spot size x-ray source 310 illuminates a sample 10. An electron bombardment laboratory X-ray source 30 is preferably used. These systems comprise an electron gun that generates an electron beam that is directed at a target. Typically, the target is selected from chromium, tungsten, platinum, silver molybdenum, rhodium and/or gold. Multiple imaging systems 314, possibly one for each energy, are used. Preferably each of the imaging systems 314 comprises a condenser lens 316a, 316b and an objective lens 318a, 318b, with associated positioning systems 320, 322. Specifically, condenser positioning system 320 is used to position the condenser of either the first imaging system 316a or the condenser of the second imaging system 316b into the optical train. Likewise, objective positioning system 322 is used to position the objective of the first imaging system 318a or the objective of the second imaging system 318b into the optical train. Near the detector plane 324, an energy-selection device 326, such as for example a multilayer or crystal monochromator, reflects the radiation with desired energy to the detector 328. Depending on the energy selection, the imaging paths can share a single detector which will rotate with the monochromator using a pivot actuator 330 or a series of detectors 328, 328′ each detector being optimized for a different energy. Presently, the positioning of the energy selection device 326 in the back focal plane, i.e., between objective 318 and the detector 328 is preferred. Generally, the energy selection device is required because zone plates lenses need the monochromator or energy selector 326 to avoid chromatic aberration. The placement near the detector is helpful because these monochromators 326 tend to have small angles of acceptance. However, because of the microscopes geometry, that is the distance between the sample 10 and objective 318 is small compared with the distance between the objective 318 and detector 328, the angular divergence of the beam is lower between the objective 318 and the detector 328. An alternative embodiment is shown in FIG. 8, in which a monochromator 326 is placed just downstream of the x-ray source 310 and reflects the radiation with different energies into a number of prepositioned imaging systems 314, one designed for each energy. In this case the sample 10 will be translated by a sample translator 340 to positions 10′ between systems to be imaged at different energies. Specifically, a first condenser 316a and first objective 318a are used to form an image on a first detector 328a; a second condenser 316b and second objective 318b are used to form an image on a second detector 328b; and a third condenser 316c and third objective 318c are used to form an image on a third detector 328c. The disadvantage of this design, in comparison with one illustrated in FIG. 7, is that the bandwidth of the monochromator must be large enough to cover the angular acceptance of the condenser lenses 316a, b, c. Therefore it is suited for cases where the numerical aperture of the imaging system is relatively low. In special cases where one or more characteristic emission lines can be selected by an in-line filter, a design shown in FIG. 9 provides a simple implementation. In this embodiment, the in-line filters 350 are inserted into the beam 312 to select beam energy while the corresponding imaging systems 314, each comprising condensers 316a, b and objective lenses 318a, b are selectively inserted into the beam path 312 to perform the imaging. In some implementations, metal film energy filters are used to select the 1.8 keV energy. Further, selectivity is achieved by further pairing the filter 350 with thin scintillators to select the 1.8 keV energy. Where three emission lines of tungsten are used to image copper features in silicon substrate, the imaging system for one or more energies may employ different contrast mechanisms. A design for such a system is shown in FIG. 10. This system is similar to that shown in FIG. 8, except that imaging system for energy #3 uses a Zernike phase contrast scheme, including a phase plate 360, while others “b” and “c” use the bright-field mode. In other examples, wherein the different contrast mechanisms include absorption contrast, phase contrast, and/or Nomarski interference contrast. Beside imaging systems that employ lenses to magnify the image, the energy optimization and imaging schemes discussed above also apply to simpler imaging systems such as direct projection configurations as shown in FIG. 11, where a monochromator 326 is placed just downstream of the x-ray source 310 and directs the radiation 312 of different energies to corresponding imaging systems. The radiation 312 is generally collimated since condenser and possibly no objective are used. In each imaging system, detector 328a, 328b, 328c are place directly behind the samples 10, 10′, 10″ to record the spatial radiation pattern transmitted through it. A variation of this system is shown in FIG. 12, where the monochromator is replaced by a in-line energy filter 350 in the projection system. While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.
	summary
	description	This Application is the U.S. National Stage of PCT/JP2018/027989, filed Jul. 25, 2018, which claims priority to Japanese Patent Application No. 2017-153612, filed Aug. 8, 2017, the contents of each of which are incorporated herein by reference in entirety. The present invention relates to a cask and a method of producing neutron shields. Spent fuel assemblies removed from nuclear reactors (hereinafter, simply referred to as “fuel assemblies”) are conventionally stored in storage pools in buildings and cooled over several to a dozen or so years. The fuel assemblies are then put into dry storage over several tens of years in intermediate storage facilities or other facilities. Since the fuel assemblies continue to emit radiation such as neutrons and gamma rays, they are housed in a cask serving as a special container during transport and dry storage. The cask includes a cask body that houses fuel assemblies, an outer cylinder surrounding the cask body, and a plurality of fins aligned in a circumferential direction between the cask body and the outer cylinder. Spaces sectioned by the cask body, the outer cylinder, and the fins are filled with a neutron shielding material containing a resin. The neutron shielding material attenuates the radiation of neutrons emitted from the fuel assemblies to the outside of the cask. Japanese Patent Application Laid-Open Nos. 2004-125763 (Document 1) and 2001-318187 (Document 2) disclose casks capable of efficiently conducting decay heat emanating from fuel assemblies to outer cylinders. In these casks, neutron shields molded in another place are inserted into spaces sectioned by a cask body, the outer cylinder, and heat conduction fins. The neutron shields are formed by filling internal spaces of a copper or aluminum honeycomb member with a resin (neutron shielding material). Incidentally, in a cask, the neutron shielding material has a higher thermal expansion coefficient than materials (e.g., carbon steel) used for the cask body and the outer cylinder, and therefore great stress may be exerted on the outer cylinder or other components by thermal expansion of the neutron shielding material when the fuel assemblies are housed in the cask. In design of a cask, such stress is desirably as small as possible. The present invention is intended for a cask, and it is an object of the present invention to reduce stress that may be exerted on an outer cylinder or other components due to thermal expansion of a neutron shielding material. The cask according to the present invention includes a cask body having a tubular shape with a central axis as a center and capable of housing a fuel assembly, a tubular outer cylinder surrounding the cask body, a plurality of fins aligned in a circumferential direction in a tubular space formed between the cask body and the outer cylinder, and connecting an outer peripheral surface of the cask body and an inner peripheral surface of the outer cylinder to divide the tubular space into a plurality of divided spaces, and a plurality of neutron shields containing a neutron shielding material with which the plurality of divided spaces is filled. Each neutron shield includes a void portion that extends in an axial direction along the central axis. The present invention can reduce stress that may be exerted on the outer cylinder or other components by thermal expansion of the neutron shielding material. In a preferable embodiment of the present invention, each neutron shield further includes a molded pipe portion including a hollow portion that is the void portion, and a filled portion serving as the neutron shielding material with which a space between the molded pipe portion and an outer edge of a divided space is filled. In this case, preferably, the molded pipe portion is formed of a molded member of a neutron shielding material. The molded pipe portion may include a first precast member disposed on one side of the void portion in a section perpendicular to the axial direction, and a second precast member disposed on the other side of the void portion in the section and joined to the first precast member to surround the void portion with the first precast member. Preferably, a joint between the first precast member and the second precast member has a labyrinth structure. In another preferable embodiment of the present invention, the void portion has a shape extending in the circumferential direction in a section perpendicular to the axial direction. The present invention is also intended for a method of producing a neutron shield in a cask. In the method of producing a neutron shield, the cask includes a cask body having a tubular shape with a central axis as a center and capable of housing a fuel assembly, a tubular outer cylinder surrounding the cask body, and a plurality of fins aligned in a circumferential direction in a tubular space formed between the cask body and the outer cylinder, and connecting an outer peripheral surface of the cask body and an inner peripheral surface of the outer cylinder to divide the tubular space into a plurality of divided spaces. The method of producing the neutron shield includes disposing a molded pipe portion in a divided space, the molded pipe portion including a hollow portion extending in an axial direction along the central axis, and forming a filled portion by filling a space between the molded pipe portion and an outer edge of the divided space with a neutron shielding material with fluidity and hardening the neutron shielding material. These and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. FIG. 1 illustrates an outer appearance of a cask 1 according to an embodiment of the present invention. The cask 1 is a container capable of housing fuel assemblies 9 (i.e., spent fuel assemblies). For example, the cask 1 has a substantially circular columnar shape around a central axis J1 pointing in an up-down direction in FIG. 1. In the following description, the up-down direction along the central axis J1 in FIG. 1 is also referred to as an “axial direction.” FIGS. 2 and 3 illustrate part of a section of the cask 1 (in the vicinity of a later-described outer cylinder 3). FIG. 2 illustrates a section of the cask 1 that is perpendicular to the central axis J1, and FIG. 3 illustrates a section of the cask 1 that includes the central axis J1. The cask 1 includes a cask body 2, the outer cylinder 3, a plurality of fins (heat conduction fins) 4, and a plurality of neutron shields 5. The cask body 2 is a tubular container with the central axis J1 as its center. The cask body 2 is formed of a metal such as carbon steel. The cask body 2 includes a body side wall 21 and two body ends 22a and 22b. For example, the body side wall 21 has a substantially circular cylindrical shape extending in the axial direction. Each of the body ends 22a and 22b has a substantially circular columnar shape or substantially disk-like shape. The two body ends 22a and 22b respectively block openings at the opposite ends of the body side wall 21 in the axial direction. In the example in FIG. 3, both of the body ends 22a and 22b serve as removable lids. For example, the body ends 22a and 22b are fixed with bolts to the body side wall 21. Depending on the design of the cask body 2, one of the body ends may be integrally formed with the body side wall 21. By removing the body ends serving as lids, the cask 1 is capable of housing a plurality of fuel assemblies 9 (see FIG. 1) in the cask body 2. In actuality, the internal space of the cask body 2 is partitioned by baskets so as to prevent the fuel assemblies 9 from coming in contact with one another. The outer cylinder 3 has a tubular shape with the central axis J1 as its center and surrounds the body side wall 21 of the cask body 2. The outer cylinder 3 is formed of a metal such as carbon steel. The outer cylinder 3 includes an outer-cylinder side wall 31 and two outer-cylinder ends 32a and 32b (see FIG. 3). For example, the outer-cylinder side wall 31 has a substantially circular cylindrical shape extending in the axial direction. The diameter of the outer-cylinder side wall 31 is larger than the diameter of the body side wall 21. A tubular space 41 with the central axis J1 as its center is formed between the body side wall 21 and the outer-cylinder side wall 31, i.e., between an outer peripheral surface 211 of the cask body 2 and an inner peripheral surface 311 of the outer cylinder 3. The tubular space 41 has a substantially circular ring shape in a section perpendicular to the central axis J1. The tubular space 41 extends along the entire length of the outer-cylinder side wall 31 in the axial direction. The two outer-cylinder ends 32a and 32b have substantially circular ring shapes and respectively block (almost seal) the opposite ends of the tubular space 41 in the axial direction. For example, the outer-cylinder ends 32a and 32b are bonded to the outer-cylinder side wall 31 and the body side wall 21 by welding or other methods. The fins 4 are aligned in a circumferential direction around the central axis J1 in the tubular space 41. The fins 4 are formed of a metal such as copper. Each fin 4 is a heat conduction member that connects the outer peripheral surface 211 of the cask body 2 and the inner peripheral surface 311 of the outer cylinder 3. For example, each fin 4 is welded to the body side wall 21 and the outer-cylinder side wall 31. The locations of connection of the fins 4 to the outer peripheral surface 211 of the cask body 2 are arranged at almost regular intervals in the circumferential direction. The locations of connection of the fins 4 to the inner peripheral surface 311 of the outer cylinder 3 are also arranged at almost regular intervals in the circumferential direction. In the cask 1, the tubular space 41 is divided into a plurality of divided spaces 42 (see FIG. 2) by the fins 4. Each divided space 42 is a space filled with a later-described neutron shielding material. The fins 4 have a smaller length in the axial direction than the outer cylinder 3. In the example in FIG. 3, the fins 4 are not provided in opposite end portions of the outer cylinder 3 in the axial direction, and the fins 4 are provided only in a central portion of the outer cylinder 3. As illustrated in FIG. 2, the neutron shields 5 are provided respectively in the divided spaces 42. In actuality, every divided space 42 is provided with a neutron shield 5. Each neutron shield 5 includes a molded pipe portion 50 and a filled portion 55. The molded pipe portion 50 is formed of a neutron shielding material. The neutron shielding material is, for example, a polymeric material containing large amounts of hydrogen, and is also called a “resin.” The neutron shielding material can serve as a shield against neutrons. One example of the neutron shielding material is an epoxy resin obtained by mixing boron carbide (B4C) and aluminum hydroxide. The neutron shielding material is thermoplastic. The molded pipe portion 50 extends in the axial direction and has approximately the same length as the outer cylinder 3. The molded pipe portion 50 has a hollow portion 59 extending along the entire length thereof in the axial direction. As will be described later, the molded pipe portion 50 is an assembly of a plurality of precast members 51 and 52. The filled portion 55 is formed of a neutron shielding material that fills the spaces between the molded pipe portion 50, the body side wall 21, the outer-cylinder side wall 31, and the fins 4, i.e., the space between the molded pipe portion 50 and the outer edge of the divided space 42. The filled portion 55 is in the form of a hardened body of the neutron shielding material at atmospheric temperatures. The neutron shielding material forming the filled portion 55 is preferably of the same type as the neutron shielding material forming the molded pipe portion 50. In this case, the molded pipe portion 50 and the filled portion 55 can be regarded as being almost integral. The molded pipe portion 50 and the filled portion 55 do not necessarily have to have a definite boundary. The neutron shields 5 are hollow structures formed of the neutron shielding materials. Since, as described previously, the fins 4 are not provided in the opposite end portions of the outer cylinder 3 in the axial direction, the filled portions 55 of the neutron shields 5 in these opposite end portions are continuous in the circumferential direction. In the following description, the neutron shielding material for the filled portions 55 and the neutron shielding material for the molded pipe portion 50 are assumed to be of the same type, but they may be of different types. FIGS. 4 and 5 illustrate one molded pipe portion 50. FIG. 4 illustrates a section of the molded pipe portion 50 that is perpendicular to the axial direction, and FIG. 5 illustrates the molded pipe portion 50 as viewed in the circumferential direction. The molded pipe portion 50 includes a plurality of precast members 51 and 52. Each of the precast members 51 and 52 is an elongated molded member that is obtained in advance through molding (casting) of a neutron shielding material in an external device, and is a hardened body of the neutron shielding material. In the section of the molded pipe portion 50 that is perpendicular to the axial direction, the hollow portion 59 is surrounded (formed) by two precast members 51 and 52 as illustrated in FIG. 4. That is, the molded pipe portion 50 includes a first precast member 51 disposed on one side of the hollow portion 59, and a second precast member 52 disposed on the other side of the hollow portion 59 and joined to the first precast member 51 so as to surround the hollow portion 59 with the first precast member 51. An outer surface 511 of the first precast member 51 on the side opposite the hollow portion 59 has an arc-shaped outside shape. In the divided space 42, the outer surface 511 of the first precast member 51 is arranged so as to extend along the inner peripheral surface 311 of the outer cylinder 3 (see FIG. 2). An outer surface 521 of the second precast member 52 on the side opposite the hollow portion 59 has a linear outside shape. In the section of the molded pipe portion 50 illustrated in FIG. 4, an inner surface 512 of the first precast member 51 on the side opposite the outer surface 511 has a substantially arc-shaped recess 513. The recess 513 is depressed on the side opposite the second precast member 52. The inner surface 512 has stepped portions 514 on opposite outer sides of the recess 513. Parts of the stepped portions 514 that are away from the recess 513 protrude on the side opposite the outer surface 511. The edges of the stepped portions 514 have a Z-shape (dovetail shape). An inner surface 522 of the second precast member 52 on the side opposite the outer surface 521 has a substantially arc-shaped recess 523. The recess 523 is depressed on the side opposite the first precast member 51. The inner surface 522 has stepped portions 524 on opposite outer sides of the recess 523. Parts of the stepped portions 524 that are away from the recess 523 are depressed toward the outer surface 521. The edges of the stepped portions 524 have a Z shape. For example, sectional shapes of the first precast member 51 and the second precast member 52 remain constant in the axial direction. The molded pipe portion 50 has joints 53 formed by engagement between the stepped portions 514 of the first precast member 51 and the stepped portions 524 of the second precast member 52. In the section of the molded pipe portion 50, boundary lines between the stepped portions 514 and the stepped portions 524 turn back at acute angles multiple times into a Z shape, so that each joint 53 has a labyrinth structure. With the first precast member 51 and the second precast member 52 joined together, the recess 513 of the first precast member 51 and the recess 523 of the second precast member 52 oppose each other and form the previously described hollow portion 59. In the section of the molded pipe portion 50 that is perpendicular to the axial direction, the hollow portion 59 has a shape extending in the circumferential direction (in a substantially lateral direction in FIG. 4). The width of the hollow portion 59 in a radial direction (in a substantially longitudinal direction in FIG. 4) perpendicular to the circumferential direction becomes a maximum in the central portion in the circumferential direction and gradually decreases as the hollow portion 59 approaches each joint 53. In principle, each divided space 42, except the hollow portion 59 and a later-described auxiliary void portion 58, is filled with the neutron shielding material. In the following description, the hollow portion 59 is referred to as a “void portion 59.” As illustrated in FIG. 5, the molded pipe portion 50 includes a plurality of first precast members 51 coupled to one another in the axial direction, and a plurality of second precast members 52 coupled to one another in the axial direction. The first precast members 51 have the same structure. Each two first precast members 51 adjacent in the axial direction are coupled to each other, with their ends bonded together with an adhesive. The adhesive preferably contains a neutron shielding material, and more preferably contains a neutron shielding material that is of the same type as the neutron shielding material of the precast members 51 and 52 and the filled portion 55. The second precast members 52 have the same structure. Each two second precast members 52 adjacent in the axial direction are coupled to each other, with their ends bonded together with an adhesive. Each location of coupling between the first precast members 51 differs in the axial direction from any location of coupling between the second precast members 52. As illustrated in FIG. 3, spaces around the molded pipe portions 50 in the divided spaces 42, except the vicinity of the one outer-cylinder end 32a, are filled with the neutron shielding material serving as the filled portions 55. In portions of the divided spaces 42 between the outer-cylinder end 32a and end faces of the filled portions 55, the auxiliary void portions 58 are provided as spaces where the neutron shielding material does not exist. In each divided space 42, the void portion 59 and the auxiliary void portion 58 are filled with air. In the cask 1, the body ends 22a and 22b are also provided with a member (e.g., circular disk-like member) of a neutron shielding material, which is not shown. The neutron shielding materials of the neutron shields 5 and the body ends 22a and 22b serve as shields against the radiation of neutrons emitted from the fuel assemblies 9 to the outside when the fuel assemblies 9 are housed in the cask body 2. In actuality, the neutron shielding materials are not disposed in all directions around the fuel assemblies 9 housed in the cask body 2, and for example, the auxiliary void portions 58 may be shieldless portions that do not serve as shields against neutrons. In the cask 1 housing the fuel assemblies 9, the temperature of the cask body 2 increases due to, for example, decay heat emanating from the fuel assemblies 9, and following this, the temperatures of the neutron shields 5, the fins 4, and the outer cylinder 3 increase as well. For example, the temperatures of the neutron shields 5 rise up to temperatures (120 to 130° C.) higher than the glass transition point of the neutron shielding material. At this time, the neutron shielding material has a higher thermal expansion coefficient than the metal materials for the cask body 2, the fins 4, and the outer cylinder 3, and the neutron shielding material expands to a greater degree in volume than the metal materials. The neutron shielding material has the property of turning into rubber-like form as its temperature becomes higher than the glass transition point. In the actual cask 1, thermal expansion of the neutron shielding material causes the neutron shields 5 (molded pipe portions 50 and filled portions 55) to become deformed so as to reduce the cross-sectional areas of the void portions 59 that are perpendicular to the axial direction, as indicated by chain double-dashed lines in FIG. 4. To be more specific, the amount of change in the width of each void portion 59 in the radial direction becomes a maximum in the central portion in the circumferential direction and gradually decreases as the void portion 59 approaches the joints 53. Accordingly, the deformed void portion 59 has almost a constant width in the circumferential direction, i.e., the void portion 59 has a substantially linear shape in the circumferential direction. As described above, in the neutron shields 5, the neutron shielding material expands so as to compress the void portions 59, and this relatively reduces stress that may be exerted on the outer-cylinder side walls 31 and the body side walls 21 by thermal expansion of the neutron shielding material. In other words, thermal stress on the outer-cylinder side walls 31 and the body side walls 21 are absorbed by the contraction of the void portions 59. In actuality, the neutron shielding material also expands in the axial direction. At this time, the neutron shielding material extends in the axial direction so as to reduce the sizes of the auxiliary void portions 58, so that excessively great stress is not exerted on the outer-cylinder ends 32a and 32b. After several to several tens of years have passed since housing of the fuel assemblies 9 in the cask 1, decay heat or the like emanating from the fuel assemblies 9 decreases, and the temperature of the cask 1 as a whole decreases as well. Accordingly, the neutron shielding material in the neutron shields 5 contracts. At this time, in the presence of air in the void portions 59, the neutron shielding material in rubber form contracts so as to increase the cross-sectional areas of the void portions 59 that are perpendicular to the axial direction. That is, the void portions 59 are regenerated. The contraction of the neutron shielding material also expands the auxiliary void portions 58 in a similar manner. Then, the neutron shielding material is hardened when the temperature of the neutron shields 5 becomes lower than the glass transition point of the neutron shielding material. With the neutron shielding material hardened, the neutron shields 5 have approximately the same shape as their shape before housing of the fuel assemblies 9, and unexpected large shieldless portions are not generated. Next, the production of the neutron shields 5 in the cask 1 will be described with reference to FIG. 6. In the production of the neutron shields 5, the cask 1 in the middle of production is prepared by attaching the fins 4 to the outer peripheral surface 211 of the cask body 2 and attaching the outer cylinder 3 to the fins 4 (step S11). In the cask 1 in the middle of production, one ends (lower ends in FIG. 3) of the outer-cylinder side wall 31 and the body side wall 21 are bonded to the outer-cylinder end 32b, and the other ends thereof (upper ends in FIG. 3) have not yet been bonded to the outer-cylinder end 32a. The cask 1 in the middle of production is held, with the outer-cylinder end 32b disposed on the underside of the outer-cylinder side wall 31 in the vertical direction. When the cask 1 is viewed downward from above, the divided spaces 42 are upwardly open as illustrated in FIG. 7. In actuality, as illustrated in FIG. 3, the upper portion of the body side wall 21 has a flange 212 that protrudes radially outward, and the body end 22a has a portion that overlaps the flange 212 in the axial direction. FIG. 7 and FIG. 8, which is later described, do not illustrate the flange 212 and the aforementioned portion of the body ends 22a, which overlap the divided spaces 42 in the axial direction. Then, the molded pipe portions 50 are prepared (step S12). As described previously, the molded pipe portions 50 are assemblies of a plurality of first precast members 51 and a plurality of second precast members 52. In assembly of the molded pipe portions 50, either one of the first precast member 51 and the second precast member 52 are moved in the axial direction (longitudinal direction) relative to the other member, so that the stepped portions of the one member are fitted into the stepped portions of the other member. Accordingly, the first precast member 51 and the second precast member 52 are joined together. The above operation is repeated for the plurality of first precast members 51 and the plurality of second precast members 52, so that the first precast members 51 are coupled to one another in the axial direction and the second precast members 52 are coupled to one another in the axial direction. As a result, the molded pipe portions 50 with the void portions 59 extending in the axial direction are assembled. In the assembly of the molded pipe portions 50, an adhesive is used to couple the first precast members 51 together and to couple the second precast members 52 together. This prevents or reduces the possibility that, in the case of forming the filled portions 55, which will be described later, the neutron shielding material enters the void portions 59 from the locations of coupling between the first precast members 51 and the locations of coupling between the second precast members 52. In the preferable molded pipe portions 50, the locations of coupling between the first precast members 51 differ in the axial direction from the locations of coupling between the second precast members 52. Therefore, in the case of coupling each two of the first precast members 51 together, the alignment of these two first precast members 51 is completed by fitting the stepped portions 514 of the two first precast members 51 into the stepped portion 524 of one second precast member 52. The same applies to the case of coupling each two of the second precast members 52 together. Note that this adhesive is not used at the joints 53 of the first precast members 51 and the second precast members 52. The adhesive may be used at the joints 53. After the molded pipe portions 50 have been prepared, the molded pipe portions 50 are respectively disposed in the divided spaces 42 of the cask 1 in the middle of production as illustrated in FIG. 8 (step S13). As described previously, each divided space 42 is upwardly open, so that each molded pipe portion 50 can be inserted into the divided space 42 from above the divided space 42 (through a clearance between the outer edge of the flange 212 and the inner peripheral surface 311 of the outer-cylinder side wall 31 in FIG. 3). In the divided spaces 42, the outer surfaces 511 of the first precast members 51 oppose the inner peripheral surface 311 of the outer cylinder 3. In the preferable cask 1, the outer surfaces 511 of the first precast members 51 have almost the same curvatures as the inner peripheral surface 311 of the outer cylinder 3, and the outer surfaces 511 of the first precast members 51 and the inner peripheral surface 311 of the outer cylinder 3 are in contact with each other with almost no clearance therebetween. Note that there may be a clearance between the first precast members 51 and the inner peripheral surface 311 of the outer cylinder 3. Then, a liquid (or paste-like) neutron shielding material is poured into the tubular space 41. At this time, the lower part of the tubular space 41 is covered with the outer-cylinder end 32b, so that the neutron shielding material does not leak out. The neutron shielding material spreads out in the circumferential direction, i.e., into all the divided spaces 42, from above and below the fins 4. At this time, the outer surfaces 521 of the second precast members 52 are pushed toward the first precast members 51 by the poured neutron shielding material, and the stepped portions 514 of the first precast members 51 and the stepped portions 524 of the second precast members 52 are brought into intimate contact (see FIG. 4). This consequently prevents or reduces the possibility that the neutron shielding material (to be more specific, a liquid component contained in the neutron shielding material and also called a “clear resin”) may enter the void portions 59 through clearances between the stepped portions 514 and 524. As described previously, the locations of coupling between the first precast members 51 and the locations of coupling between the second precast members 52 are filled with the adhesive, and therefore the neutron shielding material does not enter the void portions 59 from these coupling locations. Note that the neutron shielding material may penetrate into the spaces between the outer surfaces 511 of the first precast members 51 and the inner peripheral surface 311 of the outer cylinder 3. The neutron shielding material is poured into the divided spaces 42 until forming a surface of the liquid (or paste-like) neutron shielding material at a position located by a predetermined distance below the upper end face of the outer-cylinder side wall 31 (see FIG. 3). Thereafter, the inpouring of the neutron shielding material is stopped. The liquid neutron shielding material contains a hardener added thereto, so that the neutron shielding material is hardened after the elapse of a predetermined period of time. As described above, the filled portions 55 are formed by filling the spaces between the outer edges of the divided spaces 42 and the molded pipe portions 50 with the neutron shielding material with fluidity and hardening the neutron shielding material (step S14). This completes the production of the neutron shields 5. In actuality, the filled portions 55 of the neutron shields 5 in a range where the fins 4 are not provided in the axial direction are contiguous in the circumferential direction. The neutron shields 5 each include the neutron shielding material with which the divided spaces 42 are filled. After the production of the neutron shields 5, the outer-cylinder end 32a is bonded to the upper ends of the outer-cylinder side wall 31 and the body side wall 21 so as to block the tops of the divided spaces 42. Next, an experiment using a test specimen that simulates the neutron shields 5 will be described. The test specimen was configured such that the molded pipe portion was disposed in a predetermined metallic container, and the neutron shielding material was charged therearound to form the filled portion. This experiment used the molded pipe portion 50 illustrated in FIG. 9. FIG. 9 illustrates one molded pipe portion 50 as viewed in the axial direction. The molded pipe portion 50 had a thin rectangular void portion 59 and did not have the stepped portions 514 and 524 illustrated in FIG. 4. To be more specific, the inner surface 522 of the second precast member 52 had a recess 523 of a given depth, whereas the inner surface 512 of the first precast member 51 had no recess. The inner surface 522 of the second precast member 52 also had notches 525 on the opposite outer sides of the recess 523, and the first precast member 51 and the second precast member 52 were joined together by applying an adhesive to the notches 525. The container housing the test specimen included a window that enabled the user to observe the void portion 59 of the molded pipe portion 50. This experiment re-created a temperature change similar to that occurring in the cask 1 housing the fuel assemblies 9, in the test specimen. Specifically, the test specimen was first heated from 20° C. to 150° C. in a constant temperature bath and then held at 150° C. for a predetermined period of time. At this time, it was confirmed through the window of the container that the void portion 59 of the molded pipe portion 50 had become smaller. In actuality, the width of the void portion 59 in the longitudinal direction in FIG. 9 became smaller in the central portion in the lateral direction in FIG. 9 than the widths thereof in the end portions. The pressure calculated from distortion of the container (pressure exerted on the container by the thermally expanding neutron shielding material) was less than 1 MPa. Then, the temperature in the constant temperature bath was reduced from 150° C. to 20° C. At this time, it was confirmed that the size of the void portion 59 had returned to the original size (returned to the size before the experiment). On the other hand, in a similar experiment conducted when the container was filled with the neutron shielding material, i.e., when the neutron shields 5 did not include the void portions 59, the pressure exerted on the container by the thermally expanding neutron shielding material was higher than or equal to 8 MPa. Accordingly, it can be said that the test specimen provided with the void portion 59 could reduce stress that may be exerted on the container by thermal expansion of the neutron shielding material. Here, a cask with no molded pipe portions 50 according to a comparative example is assumed. In the cask according to the comparative example, neutron shields are configured by filling the divided spaces 42 as a whole, except the auxiliary void portions 58, with a neutron shielding material without clearance. The neutron shields have solid sections perpendicular to the axial direction. Thus, when the fuel assemblies 9 are housed in the cask body 2, great stress is exerted on the outer-cylinder side wall 31 and the body side wall 21 by thermal expansion of the neutron shielding material of the neutron shields. Besides, the extension of the neutron shielding material in the axial direction also increases, so that it becomes necessary to design large auxiliary void portions 58 in advance. In other words, large shieldless portions (auxiliary void portions 58) need to be provided in a state in which thermal expansion of the neutron shields has not yet occurred, and this deteriorates neutron shielding performance of the cask according to the comparative example. Moreover, in the case where decay heat or the like emanating from the fuel assemblies 9 decreases and the temperatures of the neutron shields drop, the neutron shielding material contracts so as to reduce the cross-sectional areas (areas of the solid section) of the neutron shields that are perpendicular to the axial direction. At this time, clearances may be created between the fins 4 and the neutron shields, which may result in the generation of unexpected shieldless portions. In the cask 1 illustrated in FIG. 2, on the other hand, each neutron shield 5 extends in the axial direction and includes the void portion 59 surrounded directly by the neutron shielding material. Accordingly, thermal expansion of the neutron shielding material is absorbed by the void portions 59, and it is possible to reduce stress that may be exerted on the outer cylinder 3 or other components by thermal expansion of the neutron shielding material. Besides, the sizes (volumes) of the auxiliary void portions 58 serving as shieldless portions can be reduced. Moreover, in the case where the temperature of the cask 1 has risen and then dropped, the void portions 59 are re-generated and the neutron shields 5 return to their shape before expansion. This suppresses the generation of unexpected shieldless portions. In a section of the cask 1 that is perpendicular to the axial direction, the void portions 59 have a shape extending in the circumferential direction. This reduces the possibility that a total radial thickness of the neutron shielding material of the neutron shields 5, which relates to the rate of neutron shielding, may greatly vary in the circumferential direction. Moreover, the void portion 59 in FIG. 4 whose width in the central portion in the circumferential direction is greater than the width in the end portions in the circumferential direction has a substantially linear shape extending in the circumferential direction as a result of the thermal expansion of the neutron shielding material. This suppresses the generation of unnecessarily large void portions 59 and suppresses an increase in the size of the cask 1. Each neutron shield 5 includes the molded pipe portion 50 and the filled portion 55, the molded pipe portion 50 being formed of a molded member of the neutron shielding material and having a hollow portion serving as the void portion 59, and the filled portion 55 being formed of the neutron shielding material that fills the space between the molded pipe portion 50 and the outer edge of the divided space 42. Accordingly, the neutron shields 5 including the void portions 59 can be easily produced. The neutron shielding material for the molded pipe portion 50 and the neutron shielding material for the filled portion 55 are of the same type, which improves compatibility of the molded pipe portion 50 and the filled portion 55 and prevents or suppresses the generation of unexpected clearances (shieldless portions) or the like between the molded pipe portion 50 and the filled portion 55. Incidentally, for example, it is also conceivable to use neutron shields obtained by filling the internal space of an aluminum or copper honeycomb material with a neutron shielding material in the divided spaces of a cask, as in Japanese Patent Application Laid-Open Nos. 2004-125763 and 2001-318187 (Documents 1 and 2 described above). In such neutron shields, however, the honeycomb material may become deformed due to thermal expansion of the neutron shielding material, and unexpected clearances (shieldless portions) may be generated between the honeycomb material and the neutron shielding material when the neutron shielding material contracts due to a temperature drop in the neutron shields. Besides, the total thickness of the neutron shielding material in the divided spaces is reduced by an amount corresponding to the honeycomb material. In contrast, in the cask 1, the molded pipe portions 50 themselves are formed of a neutron shielding material. Thus, it is possible to prevent the total thickness of the neutron shielding material (rate of neutron shielding) from being reduced due to the presence of members formed of other types of materials. Also, since, as described previously, the void portions 59 are re-generated when the neutron shielding material contracts, it is possible to suppress the generation of unexpected shieldless portions. In the production of the neutron shields 5, the molded pipe portions 50 are formed of divided precast portions (a plurality of precast members 51 and 52). Thus, the molded pipe portions 50 can be handled more easily than in the case where the molded pipe portions 50 are integrally formed. Besides, the first precast members 51 and the second precast members 52 are joined together by fitting the stepped portions 514 and the stepped portions 524 together. This facilitates the alignment of the first and second precast members. The labyrinth structure of the joints 53 between the first precast members 51 and the second precast members 52 prevents or suppresses penetration of the liquid (or paste-like) neutron shielding material into the void portions 59 during formation of the filled portions 55. Moreover, since no adhesive is used at the joints 53, it is possible to reduce the amount of adhesive to be used and to reduce the cost necessary for the production of the neutron shields 5. It is also possible to shorten the time required for processing such as the application and hardening of the adhesive and thereby to shorten the time required for the assembly of the molded pipe portions 50. Note that in the molded pipe portion 50 in FIG. 9, the application of the adhesive to the notches 525 without clearance prevents or suppresses penetration of the neutron shielding material into the void portion 59 from clearances between the first precast member 51 and the second precast member 52. The cask 1 and the method of producing the neutron shields 5 described above may be modified in various ways. The molded pipe portions 50 may adopt any other shape in which the width of the void portions 59 becomes a maximum in the central portion in the circumferential direction and gradually degreases as the void portions 59 approach the ends in the circumferential direction. FIG. 10 illustrates one example of such molded pipe portions 50, and the molded pipe portions 50 include the void portions 59 having a rhombic shape extending in the circumferential direction. In this way, the shape of the void portions 59 may be appropriately changed. With the molded pipe portions 50 in FIGS. 4, 9, and 10 in which the void portions 59 have shapes extending in the circumferential direction (and molded pipe portions 50 in FIGS. 11 and 12, which will be described later), it is possible to reduce the possibility that the total radial thickness of the neutron shielding material may vary greatly in the circumferential direction. Each molded pipe portion 50 may include a plurality of void portions 59. In the example illustrated in FIG. 11, two void portions 59 each extending in the axial direction are aligned in the circumferential direction. Also, as illustrated in FIG. 12, each divided space 42 may include a plurality of (in FIG. 12, two) molded pipe portions 50 aligned in the circumferential direction. Depending on the design of the molded pipe portions 50, the cross-sectional shapes and sizes of the void portions 59 may be changed according to the positions of the void portions 59 in the axial direction. In the divided spaces 42, the void portions 59 do not necessarily have to be located in the vicinity of the outer cylinder 3, and for example, may be located in the vicinity of the cask body 2. Such neutron shields 5 can be easily produced by simply changing the positions of the molded pipe portions 50 in the divided spaces 42 in step S13 in FIG. 6. The molded member of the molded pipe portions 50 may be formed through machining such as cutting. The molded pipe portions 50 each may be configured of a single molded member. Alternatively, the molded pipe portions 50 each may be configured of three or more molded members at each position in the axial direction. The molded pipe portions 50 may be formed of a material other than a neutron shielding material. This material is usually a material that is not used as a neutron shielding material and is, for example, a resin or the like that contains neither boron nor cadmium. Like the neutron shielding material, this material also preferably has the property of turning into rubber form with a temperature rise. In this case, when the temperature of the cask 1 has risen and then dropped, it is possible to re-generate the void portions 59 and suppress the generation of shieldless portions. In the above-described cask 1, the filled portions 55 of the neutron shields 5 in the opposite end portions of the outer cylinder 3 in the axial direction are contiguous in the circumferential direction. However, in cases such as where each fin 4 extends from one end of the outer cylinder 3 to the other end thereof, the neutron shields 5 may exist in discontinuous form. For example, in a section of the cask 1 that is perpendicular to the axial direction, the inclinations of the fins 4 relative to the outer peripheral surface 211 of the cask body 2 may be gradually changed in the circumferential direction, and the divided spaces 42 may have different shapes. Even in this case, the neutron shields 5 can be produced appropriately by the above-described method of producing the neutron shields 5, in which the molded pipe portions 50 are produced by an external device, and the filled portions 55 are formed by filling the spaces between the molded pipe portions 50 and the outer edges of the divided spaces 42 with the neutron shielding material with fluidity. Depending on the design of the cask 1, the molded pipe portions 50 whose outside shapes are formed in accordance with the divided spaces 42 may be inserted into the divided spaces 42 to produce the neutron shields 5. The configurations of the above-described preferred embodiments and variations may be appropriately combined as long as there are no mutual inconsistencies. While the invention has been shown and described in detail, the foregoing description is in all aspects illustrative and not restrictive. It is therefore to be understood that numerous modifications and variations can be devised without departing from the scope of the invention. 1 Cask 2 Cask body 3 Outer cylinder 4 Fin 5 Neutron shield 9 Fuel assembly 41 Tubular space 42 Divided space 50 Molded pipe portion 51 and 52 Precast member 53 Joint 55 Filled portion 59 Void portion (hollow portion) 211 Outer peripheral surface (of cask body) 311 Inner peripheral surface (of outer cylinder) J1 Central axis S11 to S14 Step
	abstract	A method and associated apparatus for detecting concealed fissile, fissionable or special nuclear material in an article, such as a shipping container, is provided. The article is irradiated with a source of fast neutrons, and fast neutrons released by the fissile or fissionable material, if present, are detected between source neutron pulses. The method uses a neutron detector that can detect and discriminate fast neutrons in the presence of thermal neutrons and gamma radiation. The detector is able to process high count rates and is resistant to radiation damage, and is preferably a solid state neutron detector comprised of silicon carbide.
051494906	description	DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 illustrates a typical pressurizer 10 used in a nuclear reactor coolant system. Pressurizer 10 is a vertical, cylindrical vessel with replaceable electric heaters 12 in its lower section. Heaters 12 extend through heater sleeves 14 in the vessel wall 16 into the lower portion of pressurizer 10. Heaters 12 are supported by support plate 34 inside pressurizer 10. Heater sleeves 14 extend through the vessel wall 16 which is approximately six inches thick and made of carbon steel or low alloy steel. A plurality of nozzles such as that indicated by the numeral 15 may also extend through a bore in the vessel wall at a variety of locations on the pressurizer. Only one is shown for ease of illustration. As seen in FIG. 2, a cladding 18 normally made from stainless steel is used on the interior surface of the wall 16 for corrosion protection. For ease of illustration, heater 12 is not shown in FIG. 2. For purposes of simplicity, the following description is directed to the replacement of a heater sleeve. As seen in FIG. 2, the invention is generally indicated by the numeral 20. Replacement heater sleeve 20 is formed from a tubular main body portion 22 having first or upper and second or lower ends 24, 26. The lower central section of main body portion 22 is provided with enlarged wall portion 28 having a larger outer diameter than main body portion 22. The outer circumference of enlarged wall portion 28 is provided with threads 30. Flange 32 extends radially outward from main body portion 22 immediately below and to a larger outer diameter than enlarged wall portion 28. Relief groove 36 is provided at the intersection of enlarged wall portion 28 and flange 32. Weld prep 38 is provided at lower end 26 for attaching the replacement heater or any necessary piping. Replacement of a damaged original heater sleeve 14 is carried out as follows. The electric heater 12 is removed. The damaged heater sleeve 14 is removed. Heater sleeve bore 40 is partially tapped to provide threads 42 at its lower end. Replacement heater sleeve 20 is threaded into heater sleeve bore 40 such that upper end 24 is substantially flush with the interior of pressurizer 10 and the upper face of flange 32 is against the exterior of pressurizer 10. Seal weld 44, a partial penetration weld, is then provided between upper end 24 and the interior of pressurizer 10. FIG. 3 provides a plan view of replacement heater sleeve 20 in its installed position. It should be understood that references to upper and lower ends of elements are a matter of convenience and should not be construed in a limiting fashion. Relief groove 36 serves the purpose of preventing interference between the intersection of enlarged wall portion 28 and flange 32 with threads 30 and 42 as flange 32 is caused to bear against the exterior of pressurizer 10. A replacement heater is then installed through replacement heater sleeve 20. The replacement heater is welded in place utilizing weld prep 38. The use of a replacement heater sleeve that has the same inner diameter as the original heater sleeve and can be installed in the original heater sleeve bore maintains the original heater alignment and precludes the need for special alignment procedures. The surface of flange 32 that contacts the exterior of pressurizer 10 is shaped to closely match the contour of that portion of pressurizer 10 where the work is being performed. A washer may also be used between flange 32 and the exterior of pressurizer 10 to aid in providing a sealing contact. It should be understood that the method and apparatus described and illustrated are applicable to the replacement of a heater sleeve or a nozzle. The terms heater sleeve and nozzle should be considered as interchangeable for the purposes of this description since it is common in the industry to refer to a heater sleeve as a heater nozzle. Therefore, reference to the replacement of a nozzle in the claims should be understood as being applicable to a nozzle or a heater sleeve. Because many varying and differing embodiments may be made within the scope of the inventive concept herein taught and because many modifications may be made in the embodiment herein detailed in accordance with the descriptive requirement of the law, it is to be understood that the details herein are to be interpreted as illustrative and not in a limiting sense.
	claims	1. A method for the separation of rare-earth fission product poisons from spent nuclear fuel comprising:a) providing a spent nuclear fuel comprising UO2 and rare-earth oxides;b) said step of providing said nuclear fuel comprises providing a nuclear fuel and performing one or more oxidation-reduction cycles each cycle comprising:i. oxidizing said nuclear fuel; andii. reducing said nuclear fuel;c) providing a compound comprising Th or Zr;d) mixing said provided nuclear fuel and said Th or Zr into a mixture;e) heating said mixture to a temperature sufficient to reduce said UO2 of said provided nuclear fuel; andf) extracting rare-earth metals or oxides from said heated mixture thereby producing a treated nuclear fuel, whereby said treated nuclear fuel comprises said nuclear fuel with a significant reduction in rare-earths. 2. The method for the separation of rare-earth fission product poisons from spent nuclear fuel of claim 1 whereby said step of extracting rare-earth metals or oxides comprises extracting rare-earth metals or oxides from the group consisting of Sm, Gd, Nd, Eu, and combinations thereof metals or oxides thereof. 3. The method for the separation of rare-earth fission product poisons from spent nuclear fuel of claim 1 whereby:a) said step of mixing said provided nuclear fuel comprises mixing said provided nuclear fuel and Th into a mixture; andb) said step of heating said mixture comprises heating said mixture to a temperature sufficient to reduce both UO2 and any rare-earth oxides. 4. The method for the separation of rare-earth fission product poisons from spent nuclear fuel of claim 1 further comprising:a) said step of mixing said provided nuclear fuel comprises mixing said provided nuclear fuel and Zr into a mixture; andb) said step of heating said mixture comprises heating said mixture to a temperature sufficient to reduce UO2. 5. The method for the separation of rare-earth fission product poisons from spent nuclear fuel of claim 1 whereby said step of providing said nuclear fuel comprises:a) providing nuclear fuel;b) crushing said nuclear fuel into a powder; andc) oxidizing said nuclear fuel to a temperature between 200-800° C. 6. The method for the separation of rare-earth fission product poisons from spent nuclear fuel of claim 1 whereby said step of oxidizing said nuclear fuel comprises:a) oxidizing said nuclear fuel to a temperature of 400-600° C. 7. The method for the separation of rare-earth fission product poisons from spent nuclear fuel of claim 1 whereby said step of heating said mixture comprises:a) heating said mixture in a vacuum, heating said mixture in an inert gas, heating said mixture in a reducing fluid, or a combination thereof. 8. The method for the separation of rare-earth fission product poisons from spent nuclear fuel of claim 1 whereby said step for extracting rare-earth metals comprises vaporization, selective chlorination, air classification, or a combination thereof. 9. The method for the separation of rare-earth fission product poisons from spent nuclear fuel of claim 1 whereby said step of extracting rare-earth metals or oxides comprises:a) exposing said heated mixture to a chlorine gas at a temperature and pressure capable of converting said uranium to uranium chloride, rare-earth metals and oxides to rare-earth chlorides and rhodium metal to rhodium chloride;b) heating said rare-earth chlorides and rhodium chloride to a temperature capable of creating a significant vapor pressure of the rare-earth chlorides and rhodium chloride; andc) extracting said heated rare-earth chlorides and rhodium chloride using a carrier gas or in vacuum and fractional vaporization, whereby rare-earth chlorides and rhodium chloride are segregated from uranium chloride. 10. The method for the separation of rare-earth fission product poisons from spent nuclear fuel of claim 1 whereby said step of extracting rare-earth metals or oxides comprises:a) oxidizing said heated mixture, whereby oxides of uranium and thorium are formed; andb) exposing said oxidized heated mixture to temperature up to 750° C. and a pressure whereas the rare-earth oxides and rhodium form chlorides. 11. The method for the separation of the rare-earth fission product poisons from spent nuclear fuel of claim 1 further comprising:a) enriching said treated nuclear fuel comprising the steps of adding U-235, said treated nuclear fuel not exceeding 17 weight percent of U-235; andb) subjecting said enriched treated nuclear fuel to nuclear fission. 12. The method for the separation of the rare-earth fission product poisons from spent nuclear fuel of claim 1 further comprising:a) enriching said treated nuclear fuel comprising the steps of adding U-235, said treated nuclear fuel not exceeding 8 weight percent of U-235; andb) subjecting said enriched treated nuclear fuel to nuclear fission. 13. The method for the separation of the rare-earth fission product poisons from spent nuclear fuel of claim 1 whereby said step of mixing and heating further comprises:a) adding a dissolving agent to said heated mixture; andb) extracting said rare-earth metals with a dissolving agent. 14. The method for the separation of the rare-earth fission product poisons from spent nuclear fuel of claim 13 whereby said dissolving agent comprises nitric acid. 15. The method for the separation of the rare-earth fission product poisons from spent nuclear fuel of claim 1 whereby said step for extracting rare-earth metals comprises:a) vaporizing rare-earth metals during said step of heating said mixture; andb) collecting said vaporized rare-earth metals on a cooled surface, whereby said cooled surface has a temperature less than said mixture. 16. The method for the separation of the rare-earth fission product poisons from spent nuclear fuel of claim 2 whereby:a) said step of mixing said provided nuclear fuel comprises mixing said provided nuclear fuel and Th into a mixture;b) said step of heating said mixture comprises heating said mixture to a temperature above 850° C. and sufficient to reduce both UO2 and any rare-earth oxides; andc) said step for extracting rare-earth metals comprises:i. vaporizing rare-earth metals during said step of heating said mixture; andd) collecting said vaporized rare-earth metals on a cooled surface, whereby said cooled surface has a temperature less than said heated mixture. 17. The method for the separation of the rare-earth fission product poisons from spent nuclear fuel of claim 16 whereby:a) said step of heating said mixture comprises heating said mixture in a vacuum, heating said mixture in an inert gas, heating said mixture in a reducing fluid, or a combination thereof;b) said step for extracting rare-earth metals comprises vaporization, selective chlorination, air classification, or a combination thereof;c) enriching said treated nuclear fuel comprising the steps of adding U-235, said treated nuclear fuel not exceeding 8 weight percent of U-235; andd) subjecting said enriched treated nuclear fuel to nuclear fission. 18. The method for the separation of the rare-earth fission product poisons from spent nuclear fuel of claim 2 further comprising:a) said step of mixing said provided nuclear fuel comprises mixing said provided nuclear fuel and Zr into a mixture;b) said step of heating said mixture comprises heating said mixture to a temperature less than 600° C. and sufficient to reduce UO2; andc) whereby said step of extracting rare-earth metals or oxides comprises:i. exposing said heated mixture to a chlorine gas at a temperature and pressure capable of converting said uranium and rare-earth metals of said heated mixture to uranium chloride and rare-earth chlorides;ii. heating said rare-earth chlorides to a temperature capable of creating a significant vapor pressure of the rare-earth chlorides; andiii. extracting said heated rare-earth chlorides using a carrier gas or in vacuum and fractional vaporization to segregate the rare-earth chlorides and rhodium chloride from uranium chloride. 19. The method for the separation of the rare-earth fission product poisons from spent nuclear fuel of claim 18 whereby:a) said step of heating said mixture comprises heating said mixture in a vacuum, heating said mixture in an inert gas, heating said mixture in a reducing fluid, or a combination thereof;b) said step for extracting rare-earth metals comprises vaporization, selective chlorination, air classification, or a combination thereof;c) enriching said treated nuclear fuel comprising the steps of adding U-235, said treated nuclear fuel not exceeding 8 weight percent of U-235; andd) subjecting said enriched treated nuclear fuel to nuclear fission.
042591520	summary	BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to welds and methods and apparatus for detecting development of a failure within a weld, particularly useful in nuclear reactor systems. 2. Description of the Prior Art In order to ensure reliability of any structural system including fastened components, such as those joined by welds, it is common practice for the welded area to be periodically inspected for evidence of crack initiation, metal separation or other failure. While many devices are available for such inspections, some provide indications not consistent with the degree of accuracy required, and some are not readily adaptable to remote use. An application where accurate and rapid indications of weld failure are particularly desirable is in nuclear reactors, particularly in relation to main structural components within the reactor vessel which support the nuclear core. For example, while the core of fuel assemblies is typically bottom supported by a lower support structure, control rods which are reciprocatingly insertable to control core reactivity are top mounted. In the unlikely event of failure of the lower support structure attachment welds, undesirable separation of, or interference between, the control rods and fuel assemblies could result. In-service inspection programs have been instituted by the nuclear industry for inspection of such welds, including remote visual indicators useful, for example, in water-cooled reactors. With liquid metal cooled reactors, however, such visual indicators are not readily adaptable as a result of the opaque nature of the coolant. And, typical inspection systems require costly items such as multiple access ports and equipment and time consuming inspections carried out closely adjacent to the welded area. In order to detect flaws in other reactor components, such as fuel rods, liquid metal reactors have been proposed which include the incorporation of tag gases within the fuel rods. The reactors include flow paths for directing tag gases released upon failure of a fuel rod to a monitoring and detection system which alerts the plant operator to such failure. Such reactors additionally are designed to prevent the accumulation of gas bubbles which could be swept through the core region. Accordingly, reactor internals are typically configured to vent any gas which enters the reactor system to a cover gas region above the core. The venting system thus permits gases released outside of the core to flow upwardly and eventually mix with any tag and fission product gases released from fuel assemblies within the core. It is desirable to provide arrangements which allow rapid and accurate weld failure indication. It is particularly desirable to provide such arrangements in nuclear reactors, and to take advantage of existing system designs and configurations. SUMMARY OF THE INVENTION This invention provides method and apparatus for detecting cracks or other failures in welds joining plural components, particularly beneficial to remote detection in liquid metal cooled nuclear reactor systems. In one embodiment a hole or chamber is drilled from a surface of one component, through the weld deposit and into, but not entirely through, the second component. A preselected tag gas is placed within the chamber, and the chamber is sealed at its outer end, such as by a threaded and/or welded plug. Any well-known manner is provided to direct the environment immediately about the welded area, which can be liquid or gaseous, to other well-known apparatus which detects the presence of the tag gas. A trigger gas can also be incorporated with the tag gas to actuate a detection or analyzer system which otherwise is maintained in a non-detecting condition. Detection of the tag gas indicates that a failure has developed which provides a release path between the chamber and the surface of the weld deposit or the joined components. In an alternate embodiment a plurality of chambers through a given weld area are each provided with different tag gases. Detection of plural tag gases ensures that an indication is not merely spurious, passed as leakage passed the sealing plug, and that a true failure has occurred. In another embodiment a plurality of chambers are incorporated in a single weld or in different welds, each with a different tag gas. Detection of a given tag gas thus evidences not only the existence of a weld failure, but also the location of the weld or the failed position within a specific weld. In addition to plural chambers, the volume through which a chamber passes can be varied, extending, for example, over only one weld deposit boundary and terminating within, or at a surface of, the weld deposit. A chamber can also extend from a surface of one of the joined components, through the weld deposit and to the surface of another component, requiring two sealing plugs, among other configurations. The weld failure detection arrangement is particularly beneficial in the primary structural component welds of a liquid metal cooled nuclear reactor, such as the weld joining the reactor vessel to the core support structures. Leakage from a tag gas filled chamber is readily directed, by the upward flowing coolant and the configurations of the reactor and internals components, to the cover gas at the top of the reactor vessel. The cover gas can be continuously or intermittently monitored, or monitored by a detection system actuated by a trigger gas, for evidence of the tag gas as in proposed systems for monitoring fuel rod failures.
	abstract	The invention relates to a composite structure of a sample carrier 20 and a sample holder 30 for use in a TEM, for example. The sample carrier is hereby separately embodied from the sample holder. Although such compositions are already known, the known compositions are very fragile constructions. The sample carrier according to the invention can be formed from a strip of metal, and is a simple and cheap element. Using resilient force, it clamps onto or into the sample holder. The portion of the sample holder to which the sample carrier couples also has a simple form. The sample carrier can couple to the sample holder in vacuum using a coupling tool.
	summary
	summary
	abstract	The core of a pressurized water reactor is assembled in such a way that if the fuel elements on the edge of the core are bent, these fuel elements are oriented such that the bending of the fuel elements points outwards in a convex manner. When the reactor is in operation, forces arise which increase the size of small gaps between the fuel elements at the expense of greater gaps and counteract the bending effect of the fuel elements.
	summary
046474242	description	DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings, and firstly to FIG. 1 thereof, there is shown a fuel assembly, as generally indicated by the reference character 10, which is adapted to be mechanically connected to the lower core support plate, not shown, the nuclear reactor core internals. The fuel assembly 10 is seen to include a top nozzle 12 and a bottom nozzle 14 interconnected together by means of a plurality of vertically disposed thimble or guide tubes 16 within which the reactor control or moderator rods, not shown, may be periodically disposed. The fuel rods are shown at 18 and are conventionally retained within the fuel assembly 10 by means of grid straps 20, only one of which is shown in the figure. In lieu of the centralmost guide or thimble tube 16 which is conventionally co-axially disposed within the fuel assembly 10, there is provided a latching/unlatching screw 22 which is vertically movable within the fuel assembly 10, although as shown in FIG. 1, screw 22 is disclosed as being in its lowermost vertical movement mode as determined by means of the engagement of an annular shoulder portion 24 with the upper surface 26 of fuel assembly bottom nozzle 14. The lower end of latching/unlatching screw 22 is provided with an external Acme thread portion 28 for engagement with a suitable internally threaded fixture or adapter, not shown, fixedly secured within the lower core support plate, also not shown, of the reactor internals. In this manner, when the latching/unlatching screw 22 is disposed within its lowermost mode as illustrated within FIG. 1, the fuel assembly 10 is securely mechanically latched to the lower core support plate of the reactor internals. It is seen that the lowermost region of latching/unlatching screw 22 substantially comprises a solid rod, except that an axial bore 30 is defined therein for the passage of reactor coolant therethrough. The upper regions of the latching/unlatching screw 22, however, are fabricated in the form of an integral tubular member 32 which extends from the vicinity of the bottom fuel assembly nozzle 14 upwardly to within the vicinity of the top fuel assembly nozzle 12. The lower end of tubular member 32 is provided with a hexagonally configured female socket 34 which, as will be better appreciated hereinafter, serves to receive a similarly configured head portion of an extension or latching/unlatching rod which is vertically guided downwardly within tubular member 32 for mated engagement with socket 34. In this manner, torque applied to the latching/unlatching rod is transmitted to the latching/unlatching screw socket 34 by means of their respective hexagonally configured engaged portions, whereby latching/unlatching screw 22 may be threadedly mechanically connected or disconnected from the lower core support plate adapter or fixture, not shown, depending upon the direction in which the aforenoted torque is applied and transmitted. The top nozzle 12 of the fuel assembly 10 is seen to include an annular adapter plate 36 fixedly secured in the lower end thereof and in a co-axial manner, and a coil spring 38 is seated atop adapter plate 36 and is disposed within a annular housing 40 fixedly secured to adapter plate 36. Plate 36, coil spring 38, and housing 40 all surround the upper end of guide tube 32, the latter of which is also provided a pair of diametrically opposed, vertically extending slots or grooves 42, only one of which is shown. A locking sleeve 44 is annularly disposed about the upper end of guide tube 32 so as to be interposed between tube 32 and the assemblage comprising adapter plate 36, coil spring 38, and housing 40. The lower end of locking sleeve 44 is provided with a pair of diametrically opposed, radially inwardly projecting lugs 46, only one of which is shown, for slideable disposition within guide tube slot 42. A first set of annular ratchet teeth 48 are integrally provided upon the outer peripheral surface of locking sleeve 44 so as to extend vertically upwardly, and a second set of annular ratchet teeth 50 are integrally formed upon a radially inwardly projecting flange portion of housing 40 at the upper end thereof, teeth 50 extending vertically downwardly so as to be capable of mating with ratchet teeth 48. Ratchet teeth 48 are formed upon a radially outwardly extending flanged portion of locking sleeve 44, and the coil spring 38 is therefore axially interposed between this flange and adapter 36 in order to normally bias the locking sleeve 44 in the vertically upward direction. Consequently, in the absence of vertically downwardly directed pressure upon the upper end of locking sleeve 44, the ratchet teeth 48 and 50 will be engaged whereby relative rotation between the guide tube 32 and fuel assembly top nozzle 12 will be prevented. This in turn prevents relative rotation to be achieved between latching/unlatching screw 22, which is integrally formed with guide tube 32, and fuel assembly bottom nozzle 14 as well as the lower core support plate. Therefore, once latching/unlatching screw 22 has been fully threadedly engaged within the lower core support plate, retrograde threaded unlatching cannot inadvertently occur. Threaded unlatching of latching/unlatching screw 22 can of course be readily achieved by vertically downward pressure in fact being firstly applied to the upper end of locking sleeve 44 so as to disengage locking sleeve ratchet teeth 48 from housing teeth 50, such linear movement of sleeve 44 relative to housing 40 being permitted by means of the sleeve lugs 46 riding downwardly within guide tube slots 42 against the bias of spring 38. Rotational movement of the tube 32 and screw 22, relative to the fuel assembly 10, may then be performed in order to unlatch the screw 22 from the lower core support plate, not shown, so as to facilitate removal of the fuel assembly 10 from the reactor core. Turning then to FIGS. 2-4, the new and improved refueling machine apparatus of the present invention, which will enable the aforenoted latching/unlatching mechanical connections between the fuel assembly 10 and the lower core support plate, not shown, to be achieved, will now be described. The refueling machine apparatus is generally indicated by the reference character 100 and is seen to include a conventional type stationary or outer mast 102 which is vertically suspended upon a conventional refueling machine support trolley 104 by means of a vertically disposed support tube 106. Support tube 106 and stationary mast 102 are of course co-axially disposed and, in turn, the refueling machine further includes a inner movable mast or gripper tube 108 which is co-axially disposed in a telescopic manner within outer mast 102. The lower end of gripper tube 108 is provided with suitable gripper mechanisms 110 for latching or gripping the top nozzle of of the fuel assembly 10, and the movement of gripper tube 108 is controlled by means of a suitable winch drive system 112. The drive system 112 is disposed atop suitable winch support column structure 114 which, in turn, is mounted atop the suptube 106. In accordance with the particular remote-controlled latching/unlatching mechanical connection actuating system of the present invention, the refueling machine 10 is seen to further comprise a fuel assembly latching/unlatching rod 116 co-axially disposed within the gripper tube 108, and as best seen in FIGS. 3 and 4, the upper end of latching/unlatching rod 116 is fixedly secured within a cylindrical housing 118. The upper end of housing 118 is provided with an integral, vertically extending shaft portion 120 to which is fixedly connected a winch cable assembly 122. Vertical movement of housing 118 and latching/unlatching rod 116 is therefore controlled by means of a suitable latching/unlatching winch drive system 124 which is operatively connected to cable assembly 122. The latching/unlatching winch drive system 124 is disposed atop winch support column structure 114, and may be disposed along with the gripper tube winch drive system 112 in a suitably arranged dual-winch drive system, as may be desired, and as seen in FIG. 2. As best seen in FIG. 3, the upper end of gripper tube 108 is closed by means of an end plate 126, and an idler gear 128 is rotatably supported upon end plate 126 at an eccentric location relative thereto. A spur gear 130 is rotatably mounted upon end plate 126 in a co-axial manner through means of thrust bearings 132. Spur gear 130 is seen to be enmeshed with idler gear 128, and suitable bolt fastening means 134 serve to axially retain spur gear 130 upon end plate 126 through means of flanged fixtures 136. Spur gear 130 annularly surrounds the upstanding shaft portion 120 of housing 118, and the axially extending, lower central portion of spur gear 130 projects downwardly through a central aperture 138 defined within end plate 126. In this manner, a substantially square-shaped torque tube 140 may be suspendingly fixedly supported from the lowermost end of spur gear 130 so as to extend downwardly within gripper tube 108 in a co-axial manner. Lateral stabilization of the lower end of torque tube 140 is provided by means of a plurality of equiangularly spaced, circumferentially arranged, roller mechanisms 142 fixedly secured within the sidewall portions of gripper tube 108, it being noted that only one such roller mechanism 142 is shown. It is further noted that while housing 118 has a substantially cylindrical configuration, the upper and lower ends thereof are provided with substantially square-shaped flanged portions 144 and 146, respectively, which project radially outwardly so as to engage the interior wall surfaces of torque tube 140, as also seen in FIG. 4. In this manner, relative rotation between housing 118 and its latching/unlatching rod 116, and torque tube 140, is prevented, while relative axial movement of housing 118 and rod 116 with respect to torque tube 140 is nevertheless permitted, the flanged portions 144 and 146 of housing 118 providing lateral stabilization for the upper and lower ends of housing 118 during its rectilinear translational movement within the torque tube 140. In order to impart rotational drive to the idler gear 128 and spur gear 130, such that rotational torque is in turn transmitted to torque tube 140, housing 118, and latching/unlatching rod 116, another spur gear 148 is rotatably mounted upon a sidewall portion of stationary mast 102 by means of a motor drive shaft 149 which is mounted within suitable vertically spaced brackets 150 and 152. The upper end of drive shaft 149 is connected to a reversible motor drive system, not shown. The sidewall portion of stationary mast 102 is provided with an aperture 154 through which a peripheral portion of spur gear 148 projects so as to be capable of meshing with idler gear 128 when the gripper tube assembly 108 is lowered by means of winch drive system 112 so as to perform a remote-controlled latching or unlatching operation upon the fuel assembly 10 relative to the lower core support plate of the reactor internals, not shown. A coil spring 156 is co-axially disposed about drive shaft 149 so as to be interposed between the lower bracket 152 and spur gear 148 in order to bias spur gear 148 upwardly. The spring-biasing effect upon spur gear 148 also serves to facilitate the meshing of spur gear 148 and idler gear 128 when the gripper tube assembly 108 is moved downwardly in view of the fact that should the gears not properly mesh when idler gear 128 is moved downwardly with gripper tube 108, spur gear 148 will be forced downwardly against the biasing force of spring 156 whereupon a slight rotation of drive shaft 149 will cause spur gear 148 to be properly aligned with idler gear 128 for meshing therewith, coil spring 156 then biasing the spur gear 148 upwardly to its normal position as illustrated in the figure. The drive motor for shaft 149 may be mounted upon the stationary mast at an elevational level above the water within the core cavity, or alternatively, upon the refueling machine trolley. In operation, when it is desired to remotely latch a fuel assembly 10 to the lower core support plate, the refueling machine 100 will of course be moved into its appropriate position relative to the core such that the fuel assembly 10 will be disposed above the space of the core into which the fuel assembly 10 is to be deposited or inserted. The fuel assembly 10 is of course at this time gripped by means of the gripper mechanisms 110 of the refueling machine 100, and the gripper tube winch drive 112 is actuated so as to lower the gripper tube 108, the gripper mechanisms 110, and the fuel assembly 10. When the fuel assembly 10 has been lowered such that the same is resting upon the lower core support plate, the gripper tube 108 is disposed in its position relative to stationary mast 102 as illustrated in FIG. 3. It is to be noted that at the same time, the winch drive 124 for the latching/unlatching rod 116 has also been accordingly actuated so as to maintain its relative position within gripper tube 108 as also illustrated in FIG. 3. Once the fuel assembly 10 is resting upon the lower core support plate, the winch drive 124 for the latching/unlatching rod 116 may be actuated further such that the lower end of rod 116 will be engaged within the hexagonally configured socket 34 of latching/unlatching screw 22, it being remembered that the lower end of latching/unlatching rod 116 is provided with a similarly hexagonally configured head portion, not shown. Further lowering of the winch drive 124 and the latching/unlatching rod-latching/unlatching screw assembly causes translational movement of the rod 116 and its housing 118 relative to torque tube 140, as well as similar linear translational movement of screw 22 relative to the fuel assembly 10, and particularly, bottom nozzle portion 14 thereof. Upon initial engagement of the screw 22 with the female adapter, not shown, of the lower core support plate, rotary drive is imparted to the spur gear 148 through means of its rotary drive shaft 149 and its reversible drive motor, not shown. Such rotational drive torque is of course transmitted to idler gear 128 and spur gear 130 whereby rotation is imparted to torque tube 140. As a result of the square-shaped configurations of tube 140 and latching/unlatching rod housing 118, housing 118 and rod 116 are caused to rotate whereby latching/unlatching screw 22 is caused to threadedly engage the female adapter, not shown, of the lower core support plate. Screw 22 at this time also translates relative to fuel assembly 14 until such time that the latching/unlatching screw 22 is fully threadedly engaged within the lower core support plate adapter. At such time, the screw 22 will be disposed relative to fuel assembly 10 as shown in FIG. 1, with the shoulder portion 24 of screw 22 engaged with the upper surface 26 of fuel assembly bottom nozzle 14. During this threading engagement period, rod 116 and housing 118 also translate relative to torque tube 140. It is lastly noted that in conjunction with the latching procedure, rotational movement of the latching screw 22 and its guide tube 32 will not be prevented by means of the locking sleeve 44 and the ratchet teeth 48 and 50 due to the fact that the ratchet teeth 48 will in fact ratchet over teeth 50, and when the threaded latching procedure is complete, the ratchet teeth 48 and 50 are engaged under the influence of biasing spring 38 so as to prevent retrograde rotation of guide tube 32 and latching screw 22 relative to the fuel assembly top nozzle 12 whereby inadvertent unlatching of the screw 22 and the fuel assembly 10 from the lower core support plate is positively prevented. Upon completion of the threaded latching procedure, the latching/unlatching rod 116 and its housing 118 may be raised by means of winch drive 124 to their position illustrated within FIG. 3, the gripper mechanisms 110 may be disengaged from the fuel assembly top nozzle 12, and the gripper tube assembly 108 raised by means of its winch drive 112. In performance of an unlatching operation, the precise reverse procedures are accomplished with the exception that the ratchet teeth 48 and 50 must be initially disengaged so as to in fact permit torque application to the guide tube 32 and unlatching screw 22 in the direction opposite that of the latching operation. Such disengagement of the ratchet teeth 48 and 50 can be accomplished by suitable means, not shown, disposed upon the gripper tube assembly 108 and incorporated, for example, within the gripper mechanisms 110. Once the fuel assembly 10 has been gripped by the mechanisms 110, and the ratchet teeth 48 and 50 disengaged, unlatching rod 116 may be lowered into guide tube 32 for engagement with unlatching screw socket 34. Torque is then applied to unlatching rod 116 in the direction reverse of that of the latching operation whereby unlatching screw 22 is threadedly disengaged or disconnected from the lower core support plate. Screw 22 therefore also moves axially upwardly relative to bottom fuel assembly nozzle 14, and rod 116 and housing 118 similarly move axially upwardly relative to torque tube 140. Once threaded unlatching is completed, rod 116 is of course entirely withdrawn from guide tube 32, and the rod 116 and housing 118 are raised to their positions shown in FIG. 3. The unlatched fuel assembly 10 may then be lifted out from the reactor core by means of vertical upward movement of gripper tube 108. Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the present invention may be practiced otherwise than as specifically described herein.
	claims	1. An apparatus for removing thermal energy from a nuclear reactor, comprising: a heat pipe configured to absorb the thermal energy produced by the nuclear reactor; a first compartment thermally coupled to said heat pipe; first gas inlet and gas outlet ducts coupled to said first compartment; a second compartment thermally coupled to said heat pipe; and second gas inlet and gas outlet ducts coupled to said second compartment, wherein said first compartment, said first gas inlet, and said first gas outlet are pneumatically isolated from said second compartment, said second gas inlet, and said second gas outlet. 2. The apparatus according to claim 1 , further comprising: claim 1 a third compartment thermally coupled to said heat pipe; and third gas inlet and gas outlet ducts coupled to said third compartment. 3. The apparatus according to claim 2 , wherein said third compartment, said third gas inlet duct, and said third gas outlet duct are pneumatically isolated from said first compartment, said first gas inlet, and said first gas outlet. claim 2 4. The apparatus according to claim 2 , wherein said third compartment, said third gas inlet duct, and said third gas outlet duct are pneumatically isolated from said first and second gas compartments, said first and second gas inlet ducts, and said first and second gas outlet ducts. claim 2 5. The apparatus according to claim 2 , further comprising. claim 2 a fourth compartment thermally coupled to said heat pipe; and fourth gas inlet and gas outlet ducts coupled to said fourth compartment. 6. The apparatus according to claim 5 , wherein said fourth compartment, said fourth gas inlet duct, and said fourth gas outlet duct are pneumatically isolated from said first compartment, said first gas inlet, and said first gas outlet. claim 5 7. The apparatus according to claim 5 , wherein said fourth compartment, said fourth gas inlet duct, and said fourth gas outlet duct are pneumatically isolated from said first, second, and third gas compartments, said first, second, and third gas inlet ducts, and said first, second, and third gas outlet ducts. claim 5 8. The apparatus according to claim 5 , further comprising: claim 5 a fifth compartment thermally coupled to said heat pipe; and fifth gas inlet and gas outlet ducts coupled to said fifth compartment. 9. The apparatus for removing thermal energy from the nuclear reactor of claim 8 , wherein said first compartment, said fifth gas inlet duct, and said fifth gas outlet duct are pneumatically isolated from said first compartment, said first gas inlet, and said first gas outlet. claim 8 10. The apparatus for removing thermal energy from the nuclear reactor of claim 5 , wherein said fifth compartment, said fifth gas inlet duct, and said fifth gas outlet duct are pneumatically isolated from said first, second, third, and fourth gas compartments, said first, second, third, and fourth gas inlet ducts, and said first, second, third, and fourth gas outlet ducts. claim 5 11. The apparatus for removing thermal energy from the nuclear reactor of claim 1 , further comprising a plurality of heat pipes in addition to said heat pipe that are the coupled to said first compartment and said second compartment. claim 1 12. The apparatus for removing thermal energy from the nuclear reactor of claim 8 , further comprising a plurality of heat pipes in addition to said heat pipe that are thermal coupled to said first compartment, said second compartment, said third compartment, said fourth compartment and said fifth compartment. claim 8 13. The apparatus for removing thermal energy from the nuclear reactor of claim 1 , said heat pipe comprising: claim 1 an inner pipe enclosing nuclear fuel of the nuclear reactor; an outer pipe enclosing the inner pipe; and a space interposed between said inner pipe and said outer pipe. 14. The apparatus for removing thermal energy from the nuclear reactor of claim 13 , wherein said space is a vapor space that is configured to contain a fluid. claim 13 15. The apparatus for removing thermal energy from the nuclear reactor of claim 13 , wherein said outer pipe has first protusion extending into said first compartment. claim 13 16. The apparatus for removing thermal energy from the nuclear reactor of claim 15 , further comprising a second protrusion extending into said second compartment. claim 15 17. A vehicle, comprising: a nuclear reactor; an apparatus for removing thermal energy from said nuclear reactor, said apparatus comprising: a heat pipe configured to absorb thermal energy produced by the nuclear reactor; a first compartment thermally coupled to said heat pipe; first gas inlet and gas outlet ducts coupled to said first compartment; a second compartment thermally coupled to said heat pipe; and second gas inlet and gas outlet ducts coupled to said second compartment, wherein said first compartment, said first gas inlet, and said first gas outlet are pneumatically isolated from said second compartment, said second gas inlet, and said second gas outlet; and an energy conversion system configured to convert at least a portion of said thermal energy removed from said nuclear reactor by said apparus into power for the vehicle. 18. The vehicle of claim 17 , wherein said vehicle is a spacecraft. claim 17 19. The vehicle of claim 17 , wherein said energy conversion system is configured to implement a Brayton energy conversion cycle for conversion of said portion of said thermal energy removed from said nuclear reactor by said apparatus into power for the vehicle. claim 17
	abstract	The invention is related to nuclear technologies, in particular, to the technology of producing nuclear oxide fuel for fuel elements, this oxide fuel can be used for manufacturing palletized nuclear fuel from uranium dioxide to be consumed by NPPs. The essence of the invention: this method of producing palletized nuclear fuel from uranium dioxide involves preparation of uranium dioxide moulding powder with/without uranium oxide, at this point powdered uranium dioxide is used as a raw material for preparation of moulding powder. Powdered uranium dioxide should be in the following proportion: O/U=2.37±0.04, it is obtained using a renowned method—by air heating of powdered uranium dioxide (ceramic grade) with the following proportion O/U=2.01−2.15. The technical result of the invention is increased mechanical strength of sintered pellets and a larger grain size of sintered pellets.
	description	This application claims the benefit of priority from U.S. Provisional Patent Application Ser. No. 62/435,884, filed on Dec. 19, 2016, and entitled “SCANDIUM NANO RADIO PHARMACEUTICAL FOR SOLID TUMOR TREATMENT,” which is incorporated herein by reference in its entirety. This application has been sponsored by Iran Patent Center, which does not have any rights in this application. The present disclosure generally relates to radiopharmaceuticals, and more particularly to scandium nano-radiopharmaceuticals. Furthermore, the present disclosure relates to a method for preparing scandium nano-radiopharmaceutical. Radiopharmaceuticals are radioactive compounds which may be utilized for diagnosis and therapeutic purposes by administering them to a patient and then monitoring via specific imaging devices. Radiopharmaceuticals which emit radiation with short path length, for example beta radiation, are used for therapy due to their characteristic of being able to lose all their energy over a very short distance; therefore, they can cause destruction of tumor cells without harming adjacent normal cells. Therapeutic radiopharmaceuticals have higher energy and stay longer in the body than other radiopharmaceuticals for increasing treatment efficiency. Several platforms have been developed for delivery of beta radiation by encapsulating radiopharmaceuticals in different nanocarriers, for example, dendrimers to form nano-radiopharmaceuticals. Dendrimers are distinct nanostructures with different surface groups which can be used for engineering interactions between the radiopharmaceuticals and the dendrimers. Dendrimers are appropriate candidates for encapsulating metal particles, for example radioisotopes because they are structurally and chemically well-defined templates and robust stabilizers. However, high cost of preparation, low stability, low purity, and high side effects are some of the biggest challenges in preparing nano-radiopharmaceuticals; therefore, there is a need in the art for a simple and efficient method for preparing nano-radiopharmaceuticals with high purity and high stability. Furthermore, there is a need in the art to prepare radiopharmaceuticals with minimum leakage to other organs and side effects. This summary is intended to provide an overview of the subject matter of the present disclosure, and is not intended to identify essential elements or key elements of the subject matter, nor is it intended to be used to determine the scope of the claimed implementations. The proper scope of the present disclosure may be ascertained from the claims set forth below in view of the detailed description below and the drawings. In one general aspect, the present disclosure describes a method for preparing scandium nano-radiopharmaceuticals. The method may include forming a plurality of scandium-encapsulated dendrimers by encapsulating scandium in polyamidoamine (PAMAM) dendrimers, and forming the scandium nano-radiopharmaceuticals by bombarding neutrons toward the plurality of scandium-encapsulated dendrimers. The above general aspect may include one or more of the following features. In one exemplary embodiment, the PAMAM dendrimers may include PAMAM dendrimers with amine surface groups. In an exemplary embodiment, bombarding neutrons toward the plurality of scandium-encapsulated dendrimers may include bombarding neutrons toward the scandium-encapsulated dendrimers with a neutron flux between about 3×1011 and about 5×1011 n·cm−2 s−1 (neutrons per cm2 per second) for a period of time less than about 3 hours. According to some implementations, forming a plurality of scandium-encapsulated dendrimers may include forming a Sc3+-PAMAM solution by mixing a Sc(NO3)3 solution with a PAMAM solution, and forming a solution of the plurality of scandium-encapsulated dendrimers by reducing the Sc3+-PAMAM solution. In an exemplary embodiment, forming a plurality of scandium-encapsulated dendrimers may further include drying the solution of the plurality of scandium-encapsulated dendrimers to form the plurality of scandium-encapsulated dendrimers. According to some implementations, the Sc(NO3)3 solution may include Sc(NO3)3 with a concentration of about 20 mM. The PAMAM solution may include PAMAM dendrimers with a concentration of about 0.01 mM. In some exemplary embodiments, the PAMAM solution may include PAMAM dendrimers with a generation of at least 4. According to some implementations, the PAMAM solution may include PAMAM dendrimers with amine surface groups. The Sc3+ may be present in the Sc3+-PAMAM solution with an amount between about 50 and about 60 Sc3+ ions per PAMAM dendrimer. According to some implementations, the scandium nano-radiopharmaceutical may include one of scandium-47 (47Sc), or scandium-46 (46Sc), or combinations thereof. According to some implementations, forming a solution of the plurality of scandium-encapsulated dendrimers by reducing the Sc3+-PAMAM solution may include adjusting pH of the Sc3+-PAMAM solution to a pH between about 6 and about 8, forming a solution of the plurality of scandium-encapsulated dendrimer by adding a reducing agent to the Sc3+-PAMAM solution, and adjusting pH of the solution of the plurality of scandium-encapsulated dendrimer to a pH between about 2 and about 4. In another general aspect, the present disclosure describes a scandium nano-radiopharmaceutical for treating solid tumors. The scandium nano-radiopharmaceutical may include scandium (Sc) particles which may be encapsulated within polyamidoamine (PAMAM) dendrimers. The Sc particles may be present in the scandium nano-radiopharmaceutical with an amount of between 50 Sc particles per PAMAM dendrimer and 60 Sc particles per PAMAM dendrimer. The above general aspect may include one or more of the following features. In one exemplary embodiment, the Sc particles may include radioactive Sc particles. The PAMAM solution may include PAMAM dendrimers with a generation of at least 4. The PAMAM solution may include PAMAM dendrimers with amine surface groups. The scandium nano-radiopharmaceutical may include one of scandium-47 (47Sc) particles, scandium-46 (46Sc) particles, or combinations thereof. In the following detailed description, numerous specific details are set forth by way of examples to provide a thorough understanding of the relevant teachings related to the exemplary embodiments. However, it should be apparent that the present teachings may be practiced without such details. In other instances, well known methods, procedures, components, and/or circuitry have been described at a relatively high-level, without detail, in order to avoid unnecessarily obscuring aspects of the present teachings. The following detailed description is presented to enable a person skilled in the art to make and use the methods and devices disclosed in exemplary embodiments of the present disclosure. For purposes of explanation, specific nomenclature is set forth to provide a thorough understanding of the present disclosure. However, it will be apparent to one skilled in the art that these specific details are not required to practice the disclosed exemplary embodiments. Descriptions of specific exemplary embodiments are provided only as representative examples. Various modifications to the exemplary implementations will be plain to one skilled in the art, and the general principles defined herein may be applied to other implementations and applications without departing from the scope of the present disclosure. The present disclosure is not intended to be limited to the implementations shown, but is to be accorded the widest possible scope consistent with the principles and features disclosed herein. Disclosed herein is a scandium nano-radiopharmaceutical and the preparation method thereof. Scandium may be utilized for conjugating to a dendrimer as a nanocarriers to form scandium nano-radiopharmaceutical. The scandium nano-radiopharmaceutical may include scandium particles which may be encapsulated within polyamidoamine (PAMAM) dendrimers. The scandium nano-radiopharmaceutical with encapsulated scandium particles may be used for treating solid tumors, such as breast tumors and prostate tumors, through emitting beta radiation towards tumor cells, and then destroying the tumor cells. FIG. 1A shows method 100 for preparing scandium nano-radiopharmaceuticals, consistent with an exemplary embodiment of the present disclosure. Method 100 may include forming a plurality of scandium-encapsulated dendrimers by encapsulating scandium within polyamidoamine (PAMAM) dendrimers with amine surface groups (step 102), and forming a scandium nano-radiopharmaceutical by bombarding neutrons toward the plurality of scandium-encapsulated dendrimers (step 104). Step 102 may include forming a plurality of scandium-encapsulated dendrimers by encapsulating scandium within polyamidoamine (PAMAM) dendrimers with amine surface groups. FIG. 1B shows an exemplary implementation of step 102 for forming a plurality of scandium-encapsulated dendrimers by encapsulating scandium in polyamidoamine (PAMAM) dendrimers, consistent with an exemplary embodiment of the present disclosure. Forming the plurality of scandium-encapsulated dendrimers may include forming a Sc3+-PAMAM solution by mixing a Sc(NO3)3 solution with a PAMAM solution (step 112), and forming a solution of the plurality of scandium-encapsulated dendrimers by reducing the Sc3+-PAMAM solution (step 114). FIG. 2A shows a schematic an exemplary implementation of step 112 of forming a Sc3+-PAMAM solution by mixing a Sc(NO3)3 solution with a PAMAM solution. Step 112 may include forming a Sc3+-PAMAM solution including Sc3+-PAMAM dendrimers 204 through mixing a Sc(NO3)3 solution including scandium ions (Sc3+) 200 with a PAMAM solution including PAMAM dendrimers 202. In step 112, mixing the Sc(NO3)3 solution with the PAMAM solution may include stirring the Sc(NO3)3 solution including scandium ions (Sc3+) 200 and the PAMAM solution including PAMAM dendrimers 202. In an exemplary embodiment, mixing the Sc(NO3)3 solution including scandium ions (Sc3+) 200 with the PAMAM solution may be done using a magnet stirrer for a period of time between about 15 minutes and about 25 minutes under nitrogen atmosphere. In an exemplary implementation, the Sc(NO3)3 solution may include Sc(NO3)3 with a concentration of about 20 mM. The PAMAM solution may include PAMAM dendrimers with a concentration of about 0.01 mM. Moreover, the PAMAM solution may include PAMAM dendrimers 202 with a generation of at least 4 and the PAMAM dendrimers 202 may include amine surface groups. In an exemplary implementation, the Sc3+ ions 200 may be present in the Sc3+-PAMAM solution with an amount of between about 50 Sc3+ ions per PAMAM dendrimer and about 60 Sc3+ ions per PAMAM dendrimer. Step 114 may include forming a solution of the plurality of scandium-encapsulated dendrimers through reducing the Sc3+-PAMAM solution including Sc3+-PAMAM dendrimers. FIGS. 1C and 2B in combination illustrate exemplary aspects of step 114. FIG. 2B shows a schematic an exemplary implementation of step 114 of forming a solution of the plurality of scandium-encapsulated dendrimers through reducing the Sc3+-PAMAM solution. FIG. 1C shows an exemplary process of step 114 for forming the solution of the plurality of scandium-encapsulated dendrimers 206 through reducing the Sc3+-PAMAM solution including Sc3+-PAMAM dendrimers 204, consistent with an exemplary embodiment of the present disclosure. Referring to FIG. 1C, forming the solution of the plurality of scandium-encapsulated dendrimers may include adjusting pH of the Sc3+-PAMAM solution to a pH between about 6 and about 8 (step 122), forming a solution of the plurality of scandium-encapsulated dendrimers by adding a reducing agent to the Sc3+-PAMAM solution with adjusted pH (step 124), and adjusting pH of the solution of the plurality of scandium-encapsulated dendrimer to a pH between about 2 and about 4 (step 126). Step 122 may include adjusting pH of the Sc3+-PAMAM solution including Sc3+-PAMAM dendrimers 204 to a pH between about 6 and about 8. In this step, pH of the Sc3+-PAMAM solution including Sc3+-PAMAM dendrimers 204 may be adjusted to a pH between 6 and 8 by addition of a base compound to the Sc3+-PAMAM solution, for example, NaOH. Step 124 may include forming a solution of the plurality of scandium-encapsulated dendrimers 206 by adding a reducing agent to the Sc3+-PAMAM solution including Sc3+-PAMAM dendrimers 204 with an adjusted pH. In step 124, a solution of the plurality of scandium-encapsulated dendrimers 206 may be formed by adding a reducing agent, for example, NaBH4, to the Sc3+-PAMAM solution. The reducing agent may be used to reduce the Sc3+ ions in the Sc3+-PAMAM solution to zero-valent Sc particles which may be encapsulated within the PAMAM dendrimers. Step 126 may include adjusting pH of the solution of the plurality of scandium-encapsulated dendrimer 206 to a pH between about 2 and about 4. In this step, extra amount of the reducing agent may be decomposed through adjusting pH of the solution of the plurality of scandium-encapsulated dendrimer 206 to a pH between about 2 and about 4. In an exemplary embodiment, adjusting pH of the solution of the plurality of scandium-encapsulated dendrimer 206 may be done by adding an acid compound, for example, HClO4 to the solution of the plurality of scandium-encapsulated dendrimer 206. After adjusting pH of the solution of the plurality of scandium-encapsulated dendrimer, in order to complete encapsulation of scandium in PAMAM dendrimers, the reduced Sc3+-PAMAM solution may be stirred under the nitrogen atmosphere using a magnet stirrer for at least about 2 hours. In an exemplary embodiment, forming the plurality of scandium-encapsulated dendrimers may include drying the solution of the plurality of scandium-encapsulated dendrimers to form the plurality of scandium-encapsulated dendrimers. The solution of the plurality of scandium-encapsulated dendrimers may be dried using an oven for a period of time about 24 hours. Referring back to FIG. 1A, step 104 may include forming a scandium nano-radiopharmaceutical by bombarding neutrons toward the plurality of scandium-encapsulated dendrimers. Bombarding neutrons toward the plurality of scandium-encapsulated dendrimers may include bombarding neutrons toward the scandium-encapsulated dendrimers over a time period of less than 3 hours. In an exemplary embodiment, bombarding neutrons toward the scandium-encapsulated dendrimers may include bombarding neutrons toward the scandium-encapsulated dendrimers with a neutron flux between about 3×1011 and about 5×1011 n·cm−2 s−1 (neutrons per cm2 per second). In step 104, due to bombarding neutrons toward the plurality of scandium-encapsulated dendrimers, scandium particles may be activated and converted to one of scandium-47 (47Sc) radioactive isotope, scandium-46 (46Sc) radioactive isotopes or combinations thereof. Moreover, placing the scandium-encapsulated dendrimers in the heart of the reactor may cause the scandium-encapsulated dendrimers to be burnt; therefore, they may be placed in a position away from heart of the reactor, where the intensity of the radiation may be lower than the heart of the reactor, for example at a pile position. In some exemplary implementations, after preparing the scandium nano-radiopharmaceuticals, the scandium nano-radiopharmaceuticals may be used for treating solid tumors through administering a solution of the scandium nano-radiopharmaceutical to solid tumor cells. Administering the scandium nano-radiopharmaceuticals to solid tumor cells may include injecting the nano-radiopharmaceutical to a solid tumor site, emitting beta radiation from the nano-radiopharmaceutical toward the solid tumor cells, and, therefore, killing tumor cells responsive to the emitted beta radiation through absorbing the beta radiation by the tumor cells. In an exemplary embodiment, injecting the scandium nano-radiopharmaceutical to a solid tumor site may include direct injection of the scandium nano-radiopharmaceutical to the solid tumor site. Presence of the PAMAM dendrimers may enhance adhesion of the scandium nano-radiopharmaceuticals to the solid tumor site; therefore, it may prevent the leakage of the scandium nano-radiopharmaceuticals to other parts of body and their side effects. In some exemplary implementations, after injecting the scandium nano-radiopharmaceuticals to the solid tumor site, the scandium nano-radiopharmaceuticals may emit beta radiation with short path length toward the solid tumor cells. For example, energy of the beta radiation of scandium-46 (46Sc) in scandium nano-radiopharmaceutical may be about 357 keV with 100% abundance. As a result, the tumor cells may absorb the energy of the beta radiation and they may be killed responsive to the absorbing high energy of beta radiation. In this example, a scandium nano-radiopharmaceutical was prepared as follows. At first, a plurality of scandium-encapsulated dendrimers was formed by encapsulating scandium in generation 5 of polyamidoamine dendrimers with NH2 surface groups (PAMAMG5-NH2 dendrimer). In order to form a plurality of scandium-encapsulated dendrimers, scandium ions (Sc3+) were encapsulated within polyamidoamine (PAMAM) dendrimers with amine surface groups. At first, Sc3+-PAMAM solution with a concentration of about 0.01 mM was prepared through mixing a Sc(NO3)3 solution with a PAMAM solution. The Sc(NO3)3 solution was prepared through dissolving a plurality of Sc2O3 in a 1M HNO3 solution to form the Sc(NO3)3 solution with a concentration of about 20 mM. The PAMAM solution contained PAMAMG5-NH2 dendrimers which were dissolved in methanol 5% (volume/volume). The PAMAM solution had a concentration of about 0.05 mM. Mixing the Sc(NO3)3 solution with the PAMAM solution was done though stirring using a magnet stirrer for about 20 minutes under nitrogen atmosphere. After mixing the Sc (NO3)3 solution with the PAMAM solution, the Sc3+ ions were present in the Sc3+-PAMAM solution with an amount of about 55 Sc3+ ions per PAMAM dendrimer. Then, a solution of the plurality of scandium-encapsulated dendrimers was formed through reducing the Sc3+-PAMAM solution. In the reducing step, a reducing agent was used to reduce the Sc3+ ions in the Sc3+-PAMAM solution to zero-valent Sc particles which were encapsulated within the PAMAM dendrimers. In order to reduce the Sc3+-PAMAM solution, at first pH of the Sc3+-PAMAM solution was adjusted to a pH of about 7.5 using a NaOH solution with a concentration of 2 M. Then, a solution of the plurality of scandium-encapsulated dendrimers was formed through adding NaBH4 with a molar ratio of about 3:1 (NaBH4:Sc3+ particles) as a reducing agent to the Sc3+-PAMAM solution. The reducing step of the Sc3+-PAMAM solution was done under nitrogen atmosphere. After that, decomposing the excess amount of BH4− was done by adjusting pH of the solution of the plurality of scandium-encapsulated dendrimer to a pH about 3 using HClO4 with a concentration of about 70.0% (volume/volume). Then, in order to complete encapsulation of scandium in PAMAM dendrimers, the reduced Sc3+-PAMAM solution was stirred under the nitrogen atmosphere using a magnet stirrer for about 2 hours. Finally, scandium nano-radiopharmaceuticals were formed by irradiating the plurality of scandium-encapsulated dendrimers. The plurality of scandium-encapsulated dendrimers was flame sealed into a quartz ampoule, and then sealed in a cold-welding aluminium can. Irradiating the plurality of scandium-encapsulated dendrimers was done by bombarding neutrons toward the quartz ampule containing scandium-encapsulated dendrimers for about 2 hours in Tehran Research Reactor (TRR) by a neutron flux of about 3×1011 n·cm−2 s−1 (neutrons per cm2 per second). Placing the quartz ampule containing scandium-encapsulated dendrimers in the heart of the reactor causes the scandium-encapsulated dendrimers to be burnt; therefore, the quartz ampule containing scandium-encapsulated dendrimers was placed in a pile position of the reactor away from heart of the reactor. Due to irradiating the plurality of scandium-encapsulated dendrimers, scandium particles were activated and converted to radioactive scandium-46 (46Sc) particles. After irradiating the plurality of scandium-encapsulated dendrimers, the quartz ampule containing the scandium nano-radiopharmaceuticals was cooled for at least 6 hours under nitrogen atmosphere to reduce short-lived activity of some impurities, such as sodium from the reducing agent NaBH4, in the aluminium can. The half-life of sodium (Na) is short and about 15 hours; therefore, this sodium impurity was decayed after 24 hours, and the scandium nano-radiopharmaceuticals with high purity were obtained. In this example, the scandium nano-radiopharmaceuticals and the scandium-encapsulated dendrimers were characterized through different techniques, such as a scanning electron microscopy (SEM), a high resolution transmission electron microscopy (HRTEM), and a dynamic light scattering (DLS). Moreover, purity of the scandium nano-radiopharmaceuticals was tested by quality control tests such as an instant thin layer chromatography (ITLC), and a high-pressure liquid chromatography (HPLC). FIG. 3A illustrates a scanning electron microscopy (SEM) image of scandium-encapsulated dendrimers, consistent with an exemplary embodiment of the present disclosure. The SEM image was taken with a digital scanning electron microscope with a resolution of about 6.00 nm. Referring to FIG. 3A, the scandium-encapsulated dendrimers are homogenous spherical particles with a diameter between about 3 nm and about 5 nm. In these scandium-encapsulated dendrimers, the scandium particles are encapsulated within PAMAM dendrimers with a generation of 5. FIG. 3B illustrates a scanning electron microscopy (SEM) image of scandium nano-radiopharmaceuticals, consistent with an exemplary embodiment of the present disclosure. Referring to FIG. 3B, the scandium nano-radiopharmaceuticals have a larger particle size than scandium-encapsulated dendrimers of FIG. 3A. The larger particle size of the scandium nano-radiopharmaceuticals may be a result of irradiating scandium-encapsulated dendrimers to form scandium nano-radiopharmaceuticals. FIG. 4A illustrates a high-resolution transmission electron microscopy (HRTEM) image of scandium-encapsulated dendrimers with a resolution of about 5 nm in a scale of 80 nm, consistent with an exemplary embodiment of the present disclosure. FIG. 4B illustrates a high-resolution transmission electron microscopy (HRTEM) image of scandium-encapsulated dendrimers with a resolution of about 5 nm in a scale of 40 nm, consistent with an exemplary embodiment of the present disclosure. HRTEM images were obtained with a transmission electron microscope which has a point-to-point resolution of about 0.23 nm. Referring to FIGS. 4A and 4B, the HRTEM images show no agglomeration in the scandium-encapsulated dendrimers. Also, HRTEM images illustrate that the scandium-encapsulated dendrimers are monodisperse spherical particles and have a particles size between about 3 nm and about 5 nm. FIG. 5 illustrates a dynamic light scattering (DLS) graph of scandium-encapsulated dendrimers, consistent with an exemplary embodiment of the present disclosure. Referring to FIG. 5, the scandium-encapsulated dendrimers have a uniform size distribution and they have a particle size between 3 nm and 5 nm. Radiochemical purity of the scandium nano-radiopharmaceuticals was evaluated by performing an instant thin-layer chromatography (ITLC). FIG. 6A illustrates an instant thin layer chromatography (ITLC) graph of ScCl3, consistent with an exemplary embodiment of the present disclosure. Referring to FIG. 6A, radiochemical purity of the scandium particles was ascertained by using ITLC. FIG. 6B illustrates an instant thin layer chromatography (ITLC) graph of the scandium nano-radiopharmaceuticals, consistent with an exemplary embodiment of the present disclosure. Referring to FIG. 6B, the scandium nano-radiopharmaceuticals have a high radiochemical purity which is more than 99%. Referring to FIGS. 6A and 6B, the ITLC graph of ScCl3 has a peak at a position of about 37 mm, and the ITLC graph of the scandium nano-radiopharmaceuticals has a peak at a position of about 65 mm. Therefore, this shift toward higher positions confirms encapsulation of the scandium particles within PAMAM dendrimers. Further confirmation of the chemical purity of the scandium-encapsulated dendrimers was provided with a high-pressure liquid chromatography (HPLC). FIG. 7 illustrates a HPLC graph of the scandium-encapsulated dendrimers, consistent with an exemplary embodiment of the present disclosure. Referring to FIG. 7 the peak of the HPLC graph shows that scandium-encapsulated dendrimers have a high chemical purity which is more than 97%. In order to evaluate radionuclide purity of the scandium nano-radiopharmaceuticals, gamma spectroscopy was done. FIG. 8 illustrates gamma spectrometry of scandium nano-radiopharmaceutical, consistent with an exemplary embodiment of the present disclosure. Referring to FIG. 8, the gamma spectroscopy shows the exact gamma energies of the scandium nano-radiopharmaceutical which are about 889 and about 1120 keV; therefore, the scandium nano-radiopharmaceutical has a high radionuclide purity. In this example, in-vivo studies of the scandium nano-radiopharmaceutical. The in-vivo studies were a biodistribution analysis and an evaluation of the efficiency of the scandium nano-radiopharmaceuticals in treating solid tumors. The animal experiments were performed in accordance with the Principles of Laboratory Animal Care. These in-vivo studies were done on 20 female BALB/c mice with a body weight of about 18 grams. The mice were between 6- and 8-week-old, and they were housed in stainless steel cages in a ventilated animal room. Room temperature was maintained at about 20±2° C., and the relative humidity was about 60±10%. Moreover, 4T1 cells were purchased from Pasteur Institute of Iran. After cell culture, the 4T1 cells were injected under a part of skin in the breast site of mice for creating solid breast tumors. These in-vivo studies were done by administering a solution of the scandium nano-radiopharmaceutical with a pH of about 7. The solution of the scandium nano-radiopharmaceutical was prepared by dissolving a plurality of the scandium nano-radiopharmaceutical in a phosphate-buffered saline (PBS) solution. The biodistribution of the scandium nano-radiopharmaceuticals was evaluated as follows. The study was performed on 12 solid tumor-bearing mice between 7 and 10 days after injecting the 4T1 cells, when the diameter of solid tumor mass was about 1 cm. At first, 0.1 mL of scandium nano-radiopharmaceutical solution with a radioactivity of about 7.4 MBq/mL (megabecquerel per ml) was intravenously injected into the tail vein of each mouse. Then, the animals were sacrificed under CO2 atmosphere at specified time intervals of 4, 24 and 48 hours. After that, the specific activity of different organs, such as blood, heart, lung adrenal, stomach, intestine, liver, spleen, kidney, muscle, brain, tumor, and bone was calculated as the percentage of injected dose of the scandium nano-radiopharmaceutical solution per gram of each organ (% ID/g) using a gamma counter detector. FIG. 9 illustrates biodistribution of injected scandium nano-radiopharmaceutical in different mouse organs, consistent with an exemplary embodiment of the present disclosure. Referring to FIG. 9, comparison between ID/g percentages of different organs illustrates that the livers of mice have the highest accumulation of injected scandium nano-radiopharmaceutical solution per gram of liver organ (% ID/g). In order to evaluate the efficiency of the scandium nano-radiopharmaceuticals in treating solid-tumors, 0.1 ml of scandium nano-radiopharmaceutical solution with a radioactivity of about 3.7 MBq/ml (megabecquerel per ml) was administered to the 6 tumor-bearing mice though intra-tumor injection. Moreover, two tumor-bearing mice, C1 and C2, were specified as control groups without any administrations. Then, 2 weeks after the injection, the tumor-bearing mice were sacrificed, and the volume of solid tumor of each mouse was measured every day in two dimensions using a sliding caliper. The tumor volume was calculated with a formula of V=(ab2)/2, where “a” stands for the long axis and “b” stands for the short axis. FIG. 10 illustrates volume of solid tumors before and after administration of the scandium nano-radiopharmaceutical, consistent with an exemplary embodiment of the present disclosure. Referring to FIG. 10, volumes of tumors in all the tumor-bearing mice with the intra-tumor injection of scandium nano-radiopharmaceutical solution are decreased after the injection. However, the volumes of tumors were increased in the two control mice of C1 and C2 without any injections. Therefore, the scandium nano-radiopharmaceutical can be considered as an effective radiopharmaceutical for treating solid tumors. In order to further investigate the leakage of the scandium nano-radiopharmaceutical from the tumor to other organs, the tumor-bearing mice with the intra-tumor injection of scandium nano-radiopharmaceutical solution were analysed through a single-photon emission computed tomography (SPECT) two weeks after the injection. FIG. 11A illustrates a SPECT image of an anterior view of a tumor-bearing mouse after injection of the scandium nano-radiopharmaceutical 1000 to the tumor site 1002, consistent with an exemplary embodiment of the present disclosure. FIG. 11B illustrates SPECT image of a posterior view of a tumor-bearing mice after injection of the scandium nano-radiopharmaceutical 1000 to the tumor site 1002, consistent with an exemplary embodiment of the present disclosure. Referring to FIGS. 11A and 11B, the SPECT images illustrate that the scandium nano-radiopharmaceuticals 1000 significantly stick to the tumor cells in the tumor site 1002, and they don't leak to other parts of the mouse body. Therefore, the scandium nano-radiopharmaceuticals 1000 can't reach the healthy tissues; so, they can't kill the normal cells duo to the lower level of leakage, and the scandium nano-radiopharmaceutical 1000 only can kill tumor cells in the tumor site 1002. While the foregoing has described what are considered to be the best mode and/or other examples, it is understood that various modifications may be made therein and that the subject matter disclosed herein may be implemented in various forms and examples, and that the teachings may be applied in numerous applications, only some of which have been described herein. It is intended by the following claims to claim any and all applications, modifications and variations that fall within the true scope of the present teachings. Unless otherwise stated, all measurements, values, ratings, positions, magnitudes, sizes, and other specifications that are set forth in this specification, including in the claims that follow, are approximate, not exact. They are intended to have a reasonable range that is consistent with the functions to which they relate and with what is customary in the art to which they pertain. The scope of protection is limited solely by the claims that now follow. That scope is intended and should be interpreted to be as broad as is consistent with the ordinary meaning of the language that is used in the claims when interpreted in light of this specification and the prosecution history that follows and to encompass all structural and functional equivalents. Notwithstanding, none of the claims are intended to embrace subject matter that fails to satisfy the requirement of Sections 101, 102, or 103 of the Patent Act, nor should they be interpreted in such a way. Any unintended embracement of such subject matter is hereby disclaimed. Except as stated immediately above, nothing that has been stated or illustrated is intended or should be interpreted to cause a dedication of any component, step, feature, object, benefit, advantage, or equivalent to the public, regardless of whether it is or is not recited in the claims. It will be understood that the terms and expressions used herein have the ordinary meaning as is accorded to such terms and expressions with respect to their corresponding respective areas of inquiry and study except where specific meanings have otherwise been set forth herein. Relational terms such as first and second and the like may be used solely to distinguish one entity or action from another without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element proceeded by “a” or “an” does not, without further constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element. The Abstract of the Disclosure is provided to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. In addition, in the foregoing Detailed Description, it can be seen that various features are grouped together in various implementations. This is for purposes of streamlining the disclosure, and is not to be interpreted as reflecting an intention that the claimed implementations require more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive subject matter lies in less than all features of a single disclosed implementation. Thus, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as a separately claimed subject matter. While various implementations have been described, the description is intended to be exemplary, rather than limiting and it will be apparent to those of ordinary skill in the art that many more implementations and implementations are possible that are within the scope of the implementations. Although many possible combinations of features are shown in the accompanying figures and discussed in this detailed description, many other combinations of the disclosed features are possible. Any feature of any implementation may be used in combination with or substituted for any other feature or element in any other implementation unless specifically restricted. Therefore, it will be understood that any of the features shown and/or discussed in the present disclosure may be implemented together in any suitable combination. Accordingly, the implementations are not to be restricted except in light of the attached claims and their equivalents. Also, various modifications and changes may be made within the scope of the attached claims.
	claims	1. A writing apparatus comprising:a selector unit responsive to receipt of input data of a pattern to be written by shots of irradiation of an electron beam, configured to select a current density of the electron beam being shot and a maximal shot size thereof based on the input data of the pattern to be written; and a writing unit configured to create an electron beam with the current density selected by said selector unit, shape the created electron beam into a shot size less than or equal to said maximal shot size in units of the shots, and shoot the shaped electron beam onto a workpiece to thereby write said pattern, wherein said selector unit is configured to select the current density and the maximal shot size in such a way that, even upon input of different pattern data, a beam current value for shooting onto the workpiece the electron beam as shaped to have its size being less than or equal to the maximal shot size is less than or equal to a preset value. 2. A writing apparatus, comprising:a selector unit responsive to receipt of input data of a pattern to be written by shots of irradiation of an electron beam, configured to select a current density of the electron beam being shot and a maximal shot size thereof based on the input data of the pattern to be written; anda writing unit configured to create an electron beam with the current density selected by said selector unit, shape the created electron beam into a shot size less than or equal to said maximal shot size in units of the shots, and shoot the shaped electron beam onto a workpiece to thereby write said pattern,wherein said selector unit is configured to select the current density and the maximal shot size so that a beam current value for writing become less than or equal to a beam current value to be set in accordance with the input data of the pattern to be written. 3. The apparatus according to claim 1, wherein said workpiece has a surface as virtually divided into a plurality of pattern-writing regions and wherein said selector unit is configured to select the current density and the maximal shot size in units of the regions. 4. The apparatus according to claim 3, wherein said selector units is configured to select the current density and the maximal shot size so that a beam current value for writing become less than or equal to a beam current value to be set in units of said regions. 5. The apparatus according to claim 1, wherein when a plurality of patterns are written on the workpiece, said selector unit is configured to select the current density and the maximal shot size on a per-pattern basis. 6. The apparatus according to claim 5, wherein said selector unit is configured to select the current density and the maximal shot size so that a beam current value for writing is less than or equal to a beam current value to be set per pattern. 7. A writing method comprising:analyzing a value of a writing time pursuant to a pattern data while using as variables a current density and a maximal shot size being in a relationship that a beam current value is less than or equal to a preset value;selecting, based on a result of said analyzing, a current density and a maximal shot size so as to be in a vicinity of a point of inflexion at which the writing time value changes in concavity; andshooting an electron beam onto a workpiece with the selected current density and a shot size less than or equal to said maximal shot size to thereby write thereon a pattern pursuant to said pattern data. 8. The method according to claim 7, wherein said beam current value is set based on the pattern data. 9. The method according to claim 7, wherein said beam current value is set based on an accuracy level as required for a pattern to be written. 10. The method according to claim 7, wherein said workpiece has a surface virtually divided into a plurality of pattern-writing regions and wherein said beam current value is determined in units of the regions. 11. The method according to claim 7, wherein when a plurality of patterns are written, said beam current value is set in units of the patterns. 12. A writing apparatus comprising:a selector unit responsive to receipt of input data of a pattern to be written through more than two electron beam shots, configured to select a current density of an electron beam being shot and a maximal shot area thereof based on the inputted data of the pattern to be written; and a writing unit configured to form the electron beam with the current density as selected by said selector unit, shape the formed electron beam to have a shot area less than or equal to said maximal shot area, and shoot the shaped electron beam onto a workpiece to thereby write said pattern,wherein said selector unit is configured to select the current density and the maximal shot area in a way such that, even when inputting different pattern data, a beam current value for shooting onto a workpiece the electron beam as shaped to have its area less than or equal to the maximal shot area is less than or equal to a preset value. 13. A writing apparatus, comprising:a selector unit responsive to receipt of input data of a pattern to be written through more than two electron beam shots, configured to select a current density of an electron beam being shot and a maximal shot area thereof based on the inputted data of the pattern to be written; and a writing unit configured to form the electron beam with the current density as selected by said selector unit, shape the formed electron beam to have a shot area less than or equal to said maximal shot area, and shoot the shared electron beam onto a workpiece to thereby write said pattern,wherein said selector unit is configured to select the current density and the maximal shot area so that a beam current value for writing is not greater than a beam current value to be set pursuant to the inputted data of the pattern to be written. 14. The apparatus according to claim 12, wherein said workpiece has a surface as virtually divided into a plurality of regions and wherein said selector unit is configured to select the current density and the maximal shot area in units of said regions. 15. The apparatus according to claim 14, wherein said selector unit is configured to select the current density and the maximal shot area so that a beam current value for writing is not greater than a beam current value as set in units of said regions. 16. The apparatus according to claim 12, wherein when more than two patterns are written onto said workpiece, said selector unit is configured to select the current density and the maximal shot area on a per-pattern basis. 17. The apparatus according to claim 16, wherein said selector unit is configured to select the current density and the maximal shot area so that a beam current value for writing is less than or equal to a beam current value to be set per pattern. 18. An apparatus for writing a prespecified pattern on a workpiece through more than two shots of an electron beam, comprising:means for variably shaping shot size of a shot; andmeans for varying a current density in accordance with each shot size so that a current value of a beam being shot onto the workpiece is less than or equal to a value as preset in each shot. 19. The apparatus according to claim 2, wherein said workpiece has a surface as virtually divided into a plurality of pattern-writing regions and wherein said selector unit is configured to select the current density and the maximal shot size in units of the regions. 20. The apparatus according to claim 19, wherein said selector units is configured to select the current density and the maximal shot size so that a beam current value for writing become less than or equal to a beam current value to be set in units of said regions. 21. The apparatus according to claim 2, wherein when a plurality of patterns are written on the workpiece, said selector unit is configured to select the current density and the maximal shot size on a per-pattern basis. 22. The apparatus according to claim 21, wherein said selector unit is configured to select the current density and the maximal shot size so that a beam current value for writing is less than or equal to a beam current value to be set per pattern. 23. The apparatus according to claim 13, wherein said workpiece has a surface as virtually divided into a plurality of regions and wherein said selector unit is configured to select the current density and the maximal shot area in units of said regions. 24. The apparatus according to claim 23, wherein said selector unit is configured to select the current density and the maximal shot area so that a beam current value for writing is not greater than a beam current value as set in units of said regions. 25. The apparatus according to claim 13, wherein when more than two patterns are written onto said workpiece, said selector unit is configured to select the current density and the maximal shot area on a per-pattern basis. 26. The apparatus according to claim 25, wherein said selector unit is configured to select the current density and the maximal shot area so that a beam current value for writing is less than or equal to a beam current value to be set per pattern.
	summary
	abstract	Sealing means comprising a seal carrier and a seal connected thereto, wherein the seal carrier is removably fixable between two areas insulated from each other, and a transfer device between two chambers, which are separated by a wall, wherein said transfer device comprises a transfer mechanism and at least one sealing means according to the invention which is positioned between the wall and the transfer mechanism.
044366949	abstract	Apparatus is disclosed for decontaminating the wall of a boiling water reactor cavity. A chassis on wheels is rollable on the refueling floor along the cavity curb. A pair of horizontal wheels roll against the curb. A support member extends upwardly and laterally from the chassis to clear the personnel handrail. A mast depends from the support member into the cavity and includes a horizontal reaction wheel bearing against the cavity wall. A vertically positionable carriage is mounted on the mast and carries water spray nozzles directed against the wall.
	claims	1. An apparatus for detecting a condition in a fluid delivery system, said apparatus comprising:a motor control configured to provide electric power to an electric motor;a logic circuit in communication with the motor control; anda memory in communication with the logic circuit, wherein the memory is configured to store a first rate threshold associated with a first system condition and a second rate threshold associated with a second system condition, wherein the second rate threshold is less than the first rate threshold;wherein the logic circuit is configured to (1) determine a motor parameter at a first time within a time period and store, in the memory, a value indicative of the motor parameter at the first time associated with a value indicative of the first time and at a second time in the time period, (2) compute a change in the motor parameter within the time period as the difference between the motor parameter at the first time and the motor parameter at the second time, (3) compute an elapsed time as the difference between the second time and the first time, (4) compute a rate of change in the motor parameter within the time period as the computed change divided by the computed elapsed time, (5) store the computed rate of change in the memory, (6) compare the computed rate of change to the first rate threshold and if the computed rate of change is greater than the first rate threshold, determine that the first system condition has been detected, and (7) compare the computed rate of change to the second rate threshold and if the computed rate of change is greater than the second rate threshold but less than the first rate threshold, determine that the second system condition has been detected;wherein the motor parameter is selected from the group consisting of system current, system power, system efficiency, motor current, motor power, and motor efficiency; andwherein the first system condition corresponds to a register condition, and the second system condition corresponds to a frozen coil condition. 2. An apparatus for detecting a condition in a fluid delivery system, said apparatus comprising:a motor control configured to provide electric power to an electric motor;a logic circuit in communication with the motor control; anda memory in communication with the logic circuit, wherein the memory is configured to store a first rate threshold associated with a first system condition, a second rate threshold associated with a second system condition, wherein the second rate threshold is less than the first rate threshold, and a third rate threshold associated with a third system condition, wherein the third rate threshold is less than the second rate threshold; andwherein the logic circuit is configured to (1) determine a motor parameter at a first time within a time period and store, in the memory, a value indicative of the motor parameter at the first time associated with a value indicative of the first time and at a second time in the time period, (2) compute a change in the motor parameter within the time period as the difference between the motor parameter at the first time and the motor parameter at the second time, (3) compute an elapsed time as the difference between the second time and the first time, (4) compute a rate of change in the motor parameter within the time period as the computed change divided by the computed elapsed time, (5) store the computed rate of change in the memory, (6) compare the computed rate of change to the first rate threshold and if the computed rate of change is greater than the first rate threshold, determine that the first system condition has been detected, (7) compare the computed rate of change to the second rate threshold and if the computed rate of change is greater than the second rate threshold but less than the first rate threshold, determine that the second system condition has been detected, and (8) compare the computed rate of change to the third rate threshold and if the computed rate of change is greater than the third rate threshold but less than the second rate threshold, determine that the third system condition has been detected; andwherein the motor parameter is selected from the group consisting of system current, system power, system efficiency, motor current, motor power, and motor efficiency. 3. The apparatus of claim 2 wherein the first system condition corresponds to a register condition, the second system condition corresponds to a frozen coil condition, and the third system condition corresponds to a filter condition. 4. An apparatus for detecting a condition in a fluid delivery system, said apparatus comprising:a motor control configured to provide electric power to an electric motor;a logic circuit in communication with the motor control; anda memory in communication with the logic circuit, wherein the memory is configured to store a first rate threshold associated with a first system condition and a first scalar threshold in the memory associated with a second system condition; andwherein the logic circuit is configured to (1) determine a motor parameter at a first time within a time period and store, in the memory, a value indicative of the motor parameter at the first time associated with a value indicative of the first time, (2) determine the motor parameter at a second time in the time period, (3) compute a change in the motor parameter within the time period as the difference between the motor parameter at the first time and the motor parameter at the second time, (3) compute an elapsed time as the difference between the second time and the first time, (4) compute a rate of change in the motor parameter within the time period as the computed change divided by the computed elapsed time, (5) store the computed rate of change in the memory, (6) compare the computed rate of change to the first rate threshold and if the computed rate of change is greater than the first rate threshold, determine that the first system condition has been detected, store, in the memory, an indication that the first system condition was detected, and modify the first scalar threshold value in memory in response to a determination that the first system condition has been detected; andwherein the motor parameter is selected from the group consisting of system current, system power, system efficiency, motor current, motor power, and motor efficiency. 5. The apparatus of claim 4 wherein the logic circuit is further configured to:determine the motor parameter at a third time that is later than the first time and the second time;compare the determined motor parameter to the first scalar threshold in the memory; andif the determined motor parameter is greater than the first scalar threshold value, determine that the second system condition has been detected. 6. The apparatus of claim 5 wherein the first system condition corresponds to a register condition and the second system condition corresponds to a filter condition. 7. An apparatus for detecting a condition in a fluid delivery system, said apparatus comprising:a motor control configured to provide electric power to an electric motor;a logic circuit in communication with the motor control; anda memory in communication with the logic circuit, wherein the memory is configured to store a first rate threshold associated with a first system condition, a second rate threshold associated with a second system condition, wherein the second rate threshold is less than the first rate threshold, anda first scalar threshold in the memory associated with a third system condition; andwherein the logic circuit is configured to (1) determine a motor parameter at a first time within a time period and store, in the memory, a value indicative of the motor parameter at the first time associated with a value indicative of the first time, (2) determine the motor parameter at a second time in the time period, (3) compute a change in the motor parameter within the time period as the difference between the motor parameter at the first time and the motor parameter at the second time, (4) compute an elapsed time as the difference between the second time and the first time, (5) compute a rate of change in the motor parameter within the time period as the computed change divided by the computed elapsed time, (6) store the computed rate of change in the memory, (7) compare the computed rate of change to the first rate threshold and if the computed rate of change is greater than the first rate threshold, determine that the first system condition has been detected, store, in the memory, an indication that the first system condition was detected and modify the first scalar threshold value in memory in response to a determination that the first system condition has been detected, and (8) compare the computed rate of change to the second rate threshold and if the computed rate of change is greater than the second rate threshold but less than the first rate threshold, determine that the second system condition has been detected;wherein the motor parameter is selected from the group consisting of system current, system power, system efficiency, motor current, motor power, and motor efficiency. 8. The apparatus of claim 7 wherein the logic circuit is further configured to:determine the motor parameter at a third time that is later than the first time and the second time;compare the determined motor parameter to the first scalar threshold in the memory; andif the determined motor parameter is greater than the first scalar threshold value, determine that the third system condition has been detected. 9. The apparatus of claim 8 wherein the first system condition corresponds to a register condition, the second system condition corresponds to a frozen coil condition, and the third system condition corresponds to a filter condition. 10. The apparatus of claim 9 wherein the stored first scalar threshold corresponds to a nominal motor parameter value, and wherein the logic circuit is further configured to determine a filter life parameter based on the determined motor parameter and the nominal motor parameter value in the memory. 11. The apparatus of claim 9 wherein the logic circuit is configured to:in response to a determination that the first system condition has been detected:if the change in the motor parameter indicates that the motor is working harder to maintain a constant airflow, determine that a register close event has been detected and store, in the memory, an indication that a register has been closed; andif the change in the motor parameter indicates that the motor is working less hard to maintain a constant airflow, determine that a register open event has been detected and store, in the memory, an indication that a register has been opened. 12. The apparatus of claim 7 wherein the logic circuit is further configured to:determine the motor parameter at a third time that is later than the first time and the second time;compare the determined motor parameter to the stored first scalar threshold;if the determined motor parameter is greater than the first scalar threshold value:compute the rate of change in the motor parameter between the third time and the second time;if the computed rate of change is greater than the first rate threshold, determine that the first system condition has been detected;if the computed rate of change is greater than the second rate threshold but less than the first rate threshold, determine that the second system condition has been detected;if the computed rate of change is less than the second rate threshold, determine that the third system condition has been detected. 13. The apparatus of claim 12 wherein the first system condition corresponds to a register condition, the second system condition corresponds to a frozen coil condition, and the third system condition corresponds to a filter condition. 14. An apparatus for detecting a condition in a fluid delivery system, said apparatus comprising:a motor control configured to provide electric power to an electric motor;a logic circuit in communication with the motor control; anda memory in communication with the logic circuit, wherein the memory is configured to store a first rate threshold associated with a register condition, a second rate threshold associated with a frozen coil condition, and a nominal motor parameter;wherein the logic circuit is configured to (1) determine a motor parameter at a plurality of times within a time period, (2) compute a change in the motor parameter within the time period, (3) compute a rate of change in the motor parameter within the time period, (4) compare the computed rate of change to the first rate threshold stored in the memory, (5) if the computed rate of change is greater than the first rate threshold, determine that a register condition has been detected, and modify the nominal motor parameter value in the memory, (6) compare the computed rate of change to the second rate threshold stored in the memory, (7) if the computed rate of change is greater than the second rate threshold but less than the first rate threshold, determine that a frozen coil condition has been detected, and (8) compute a filter life parameter based on the motor parameter at the plurality of times and the nominal motor parameter value in the memory; andwherein the motor parameter is selected from the group consisting of system current, system power, system efficiency, motor current, motor power, and motor efficiency.
	claims	1. An apparatus comprising:a container that contains a parent radionuclide that decays over time into a daughter radionuclide;a container that contains a separation column that separates the daughter radionuclide from the parent radionuclide;a container that contains the separated daughter radionuclide;a plurality of containers for processing fluids;a plurality of valves and at least one pump that operate according to a predetermined process to separate the daughter radionuclide from the parent radionuclide and deliver the daughter radionuclide into the daughter radionuclide container by alternately connecting at least two of the parent radionuclide container, the daughter radionuclide container, the separation column container and the plurality of processing containers;a plurality of RFID tags including an RFID tag of the plurality of RFID tags affixed to each of parent radionuclide container, the daughter radionuclide container and the separation column;a host computer; anda programmed processor that reads an identifier of each of the plurality of RFID tags, an identifier of each of the plurality of valves and reads a position of each of the plurality of valves during one or more steps of the predetermined process and saves the identifiers of the RFID tags and valves, the positions of the valves and a duration of each step of the predetermined process into a tracking file for each batch of daughter radionuclide produced, the tracking file providing a historical archive of the production sequence and time stamps. 2. The apparatus as in claim 1 further comprising a product processor that activates the plurality of valves in sequence. 3. The apparatus as in claim 1 further comprising an RFID reader disposed in a receptacle of the separation column container that reads the identifier of the RFID of the separation column container. 4. The apparatus as in claim 1 further comprising an RFID reader disposed in a receptacle of the daughter radionuclide container that reads the identifier of the RFID of the daughter radionuclide container. 5. The apparatus as in claim 1 further comprising a plurality of processing programs where at least one of the plurality of processing programs defines a set of steps for separating the daughter radionuclide from the parent nuclide. 6. The apparatus as in claim 5 further comprising a display that depicts each of the plurality of processing programs for selection by a user. 7. The apparatus as in claim 6 further comprising a flow diagram depicted on the display showing an instantaneous flow of radionuclides through the system. 8. The apparatus as in claim 7 wherein the flow diagram is a static display and where only paths of a desired flow are highlighted. 9. The apparatus as in claim 1 further comprising a processor that saves a record of each instrument event into the tracking file. 10. An apparatus comprising:a parent radionuclide that decays over time into a daughter radionuclide;a separation column that separates the daughter radionuclide from the parent radionuclide;a plurality of valves and a pump that operate to separate the daughter radionuclide from the parent radionuclide and deliver the daughter radionuclide into a daughter radionuclide container;a plurality of RFID tags including an RFID tag of the plurality of RFID tags affixed to each of parent radionuclide container and the separation column; anda programmed processor that reads an identifier of each of the plurality of RFID tags, an identifier for each of the plurality of valves and positions each of the plurality of valves during one or more steps of the predetermined process and saves the identifiers of the RFID tags and valves, the positions, and a duration of each step of the predetermined process into a tracking file for each batch of daughter radionuclide produced, the tracking file providing a historical archive of the production sequence and time stamps.
	summary
	summary
	claims	1. A method of detecting an over-etched defect in the formation of a semiconductor device using a scanning electron microscope comprising: applying an electrical field to at least one semiconductor device, each of the at least one semicondcutor devices comprising an exposed gate electrode and at least one of source and drain contacts, the source and drain contacts connecting respectively to source and drain diffusions, each of the diffusions forming a pn junction with one of a well or substrate region, wherein the electrical field is selected to forward bias the pn junction; and detecting electrons emitted from the exposed gate electrode surface to determine the presence of a defect between the gate and one of the source and drain contacts. 2. The method as recited in claim 1 , wherein the at least one semiconductor device comprises at least two devices and further comprising determining an intensity difference between the detected electrons emitted from the gate electrode surfaces of the first and the second of the at least two devices. claim 1 3. The method as recited in claim 2 further comprising: claim 2 determining that a defect exists when the intensity difference exceeds a predetermined threshold. 4. The method as recited in claim 2 wherein each of the at least two devices is an MOS device. claim 2 5. The method as recited in claim 4 wherein the MOS device is a PMOS device and the electrical field applied is an extracting field. claim 4 6. The method as recited in claim 5 wherein the pn junction is at least one of an interface between a source region and the N-well of the PMOS device and the interface between the drain region and the N-well of the PMOS device. claim 5 7. The method as recited in claim 4 wherein the MOS device is an NMOS device and the electrical field applied is a retarding field. claim 4 8. The method as recited in claim 7 wherein the pn junction is at least one of an interface between a source region and the P-well of the NMOS device and the interface between the drain region and the P-well of the NMOS device. claim 7 9. The method as recited in claim 4 wherein the applying an electrical field and the determining the intensity difference occurs after contact holes connected to the gate and at least one of the source and drain regions have been filled with a conducting material. claim 4 10. The method as recited in claim 4 wherein the applying an electrical field and the determining the intensity difference occurs after conducting material has been deposited in the contact holes connected to the gate and at least one of the source and drain regions and after chemical mechanical polishing of the deposited conducting materials. claim 4 11. The method as recited in claim 4 wherein the applying an electrical field occurs after the semiconductor process steps of filling contact holes with a conductive material and before further fabrication steps are performed on the semiconductor. claim 4 12. The method as recited in claim 4 wherein the applying an electrical field occurs after the semiconductor process steps of depositing a conductive material in the contact holes and performing a CMP step on the filled contacts and before further fabrication steps are performed on the semiconductor. claim 4 13. The method as recited in claim 1 wherein a scanning electron microscope system applies the electrical field to the wafer. claim 1 14. The method as recited in claim 1 wherein an electrode applies the electrical field to the wafer. claim 1
	abstract	An entrainment-reducing assembly may include a container configured to hold a liquid. A venting arrangement may extend into an upper portion of the container and be configured to direct condensable and non-condensable gases into the container. A suction structure may extend into a lower portion of the container and be configured to carry out an extraction of excess liquid from the container caused by condensed gases. A deflector may be disposed between the suction structure and the venting arrangement within the container. As a result, an entrainment of uncondensed gases during the extraction of the liquid by the suction structure may be reduced or prevented, thereby protecting the pump from cavitation and failure.
059294582	claims	1. A radiation shield comprising: a flexible bag, filled with a radiation shield liquid, for shielding from radiation; rib-shaped portions extending in a vertical direction, said rib-shaped portions being integrally formed on said bag in such a manner as to project from a plurality of positions, spaced at intervals in a horizontal direction, of said bag; and reinforcement members extending in a vertical direction, said reinforcement members being provided in said rib-shaped portions in such a manner as to be integrated with said bag; whereby said bag is able to self-stand in a vertical direction with the aid of said rib-shaped portions reinforced by said reinforcement members, and said bag is able to be folded at respective portions between said rib-shaped portions arranged at the plurality of positions of said bag. 2. A radiation shield according to claim 1, further comprising connectors for releasably connecting, to each other, said rib-shaped portions adjacent to each other of a plurality of said bags which are arranged adjacently to each other. 3. A radiation shield according to claim 1, further comprising connectors for connecting the plurality of said reinforcement members of said bag to each other, said connectors being removably attached to said reinforcement members. 4. A radiation shield according to claim 1, further comprising wheels mounted on said reinforcement members of said bag. 5. A radiation shield according to claim 1, further comprising expandable link mechanism for connecting said reinforcement members of said bag to each other.
	description	The present patent document is a nationalization of PCT Application Serial Number PCT/EP2006/063093, filed Jun. 12, 2006, designating the United States, which is hereby incorporated by reference. This application also claims the benefit of DE 10 2005 028 208.3, filed Jun. 17, 2005, which is hereby incorporated by reference. The present embodiments relate to a radiation diaphragm for an x-ray facility and an x-ray facility with such a radiation diaphragm. Radiation diaphragms are used in x-ray facilities to narrow an x-ray beam produced by an x-ray tube to form a useful beam. Regions outside the useful beam are masked out by the radiation diaphragm, so that the radiation diaphragm's form decides the residual contour of the useful beam. It is expedient to vary the contour as a function of the respective task. When examining patients or bodies, the aim is to achieve a contour of the useful beam that is tailored to the volume to be examined, to avoid exposing the surrounding region to an unnecessary radiation dose. Radiation diaphragms disposed in the immediate proximity of the x-ray tube are also referred to as primary radiation diaphragms. Primary radiation diaphragms frequently have a number of individual diaphragms, disposed at different distances from the x-ray tube. The x-ray beam is initially roughly narrowed by a diaphragm disposed first in the beam path, sometimes referred to as a collimator, which brings about an approximately rectangular definition of the beam by one or two pairs of diaphragm plates. Finer definition of the beam path, the contour of which is not necessarily set as rectangular in form, then takes place by a similarly adjustable diaphragm disposed in the beam path. EP 0 485 742 discloses a further diaphragm that can be embodied as an iris diaphragm. Generally, iris diaphragms produce an approximately circular definition of the x-ray beam. The diameter or typical size of the x-ray beam can be adjusted extremely finely, usually in a continuous manner. Iris diaphragms have a relatively large number of moving parts. Iris diaphragms are complex to construct and expensive to produce. Iris diaphragms have louvers, which are mounted in a displaceable manner and bring about the actual masking of regions of the x-ray beam that are not of interest. The louvers themselves and also their mounting are susceptible to damage due to the louver movement. BE 100 9333 discloses a radiation diaphragm for a portable x-ray facility. The radiation diaphragm is designed as a perforated diaphragm. The radiation diaphragm has a radiation defining device, formed as a cylinder and disposed concentrically in relation to the x-ray tube. The radiation diaphragm has a plurality of diaphragm apertures, each being able to be positioned by rotating the radiation defining means in front of the beam emission window. The cylindrical form of the radiation defining means has to be tailored to the x-ray tube, around which it is disposed. The radiation defining means cannot be disposed freely but requires an arrangement that is concentric to the x-ray tube. This arrangement requires a complex rotational mounting, since the x-ray tube is disposed in the center of the radiation defining means, where a rotation axis should advantageously be disposed. The present embodiments may obviate one or more of the drawbacks or limitations inherent in the related art. A radiation diaphragm allows fine adjustment of the contour of the useful beam, but which is at the same time simple to construct and economical to produce. An x-ray facility may have such a radiation diaphragm. In one embodiment, a radiation diaphragm includes at least one radiation defining device mounted in a displaceable manner. The radiation diaphragm is embodied as a perforated diaphragm, which is mounted in a displaceable manner in a plane perpendicular to a beam to be limited, and which has a plurality of differently formed diaphragm apertures for the respectively differently contoured definition of the beam. The arrangement and mounting of the radiation defining device is independent to the greatest possible extent of the form and position of the x-ray tube producing the beam. The form and mounting can be designed as simply as possible, thereby also keeping production costs low. A perforated diaphragm can also be produced particularly simply, compared with an iris diaphragm. In one embodiment, the radiation defining device is mounted in a rotatable manner in the plane perpendicular to the beam. A rotational mounting can, for example, be realized with little outlay in the form of a simple rotation axis. Rotational movement can be driven and controlled in a simple manner. In one embodiment, the radiation defining device is a perforated disk with a round periphery. The space requirement of a circular disk is small, in particular during rotational movement of the circular disk. In one embodiment, the radiation diaphragm has at least two radiation defining devices. The at least two radiation defining devices are disposed in a mutually overlapping manner in the direction of the beam. The required, differently formed diaphragm apertures can be distributed over more than one radiation defining device. This allows a space-saving arrangement of the diaphragm apertures on the respective radiation defining device, so that a smaller periphery results, in particular in the case of the round radiation defining device, and the overall surface can be utilized in a more optimum manner. To double the number of diaphragm apertures, which have to be disposed on an identical radius of a round perforated disk, it would be necessary approximately to double the perforated disk radius (because circumference=2πr), with the surface content of the perforated disk however being quadrupled (because surface=π*r2). However, if the double number of diaphragm apertures is distributed over two perforated disks, there is only a doubling of the overall surface of the perforated disks. The radiation defining devices are disposed in an overlapping manner, thereby reducing their overall surface extension by the sum of the mutual overlap. In one embodiment, the radiation defining devices disposed in a mutually overlapping manner has at least two diaphragm apertures, each being able to be disposed completely within the periphery of at least one diaphragm aperture of the other radiation defining device. The diaphragm apertures can be positioned so that the beam passes through a diaphragm aperture of each radiation defining device and gives the greatest possible diversity of variation for the contours of the defined beam to be achieved. FIG. 1 shows a schematic diagram of an x-ray facility 1 with a radiation diaphragm 30. A patient to be examined 7 is supported on a patient bed 2. Below the patient bed 2 is an image receiver 5 along with associated scattered radiation grids 16 for recording x-ray images. The patient bed 2 is attached to a gantry 3. An x-ray radiation source 4 is attached to the gantry 3. The x-ray radiation source 4 has an x-ray tube 18 for producing x-ray radiation and a (conventional) primary diaphragm 17 for rough definition of the x-ray beam 6. The primary diaphragm 17 has two diaphragm plates, allowing an essentially right-angled definition. After passing through the primary diaphragm 17, the x-ray beam 6 is defined further to the required contour by the perforated disks 19 and 22, which together form a space-saving and structurally simple second radiation diaphragm. It is possible to achieve contours that are not rectangular and to set a number of dimensions for the contour. The primary diaphragm 17 and the second diaphragm formed by the perforated disks 19 and 22 together form the radiation diaphragm 30. The x-ray radiation source 4 and radiation diaphragm 30 are supplied with the necessary operating voltage and control signals by a supply line 8. The necessary electrical signals are supplied by a switchgear cabinet 9, which has a high voltage generator 10 that generates the x-ray voltage required to operate the x-ray tube 18 in addition to switching means (not shown) for generating the control signals. The switchgear cabinet 9 is connected by way of a data cable 13 to a control facility 12. The switchgear cabinet 9 is controlled by the control facility 12. The control facility 12 has a display device 15, at which current operating data and parameter settings can be displayed. A data processing facility 11 processes operator inputs, supplies preset x-ray programs for predefined recording situations, and generates the control signals for the switchgear cabinet 9. The data processing facility 11 accesses a diaphragm memory 14, which has information for adjusting the second diaphragm formed by the perforated disks 19 and 22. The diaphragm memory 14 has information, based on which, when an operator or x-ray program selects a required contour for the x-ray beam 6, the setting for the respective perforated disk 19, 22 is determined, which allows the selected contour to be best achieved. As shown in FIG. 2, the first perforated disk 19 of the second diaphragm includes a circular periphery and is mounted in a rotatable manner in a centrally disposed axis support 20. The first perforated disk 19 of the second diaphragm can be installed in a simple manner within the radiation diaphragm 30 using the axis support 20. The first perforated disk 19 of the second diaphragm includes a plurality of diaphragm apertures 60, 61, . . . , 66 of differing forms and sizes, allowing diverse contouring of an x-ray beam. The first perforated disk 19 is made from a material that does not allow the passage of x-ray radiation, for example, lead or another element with a high atomic number, so that a passing x-ray beam is blocked by the perforated disk 19 and can only pass through a respective diaphragm aperture 60, . . . , 66. The diaphragm aperture 60, . . . , 66 is simply be positioned in the x-ray beam. The differing forms and sizes of the diaphragm apertures 60, . . . , 66 are only shown schematically. The round apertures can, for example, have a respective diameter of 10 mm, 14 mm, 18 mm, 19 mm, 20 mm and 21 mm. Other individual sizes can similarly be realized. The first perforated disk 19 of the second diaphragm includes a rectangular diaphragm aperture 66. The form and size of the rectangular diaphragm aperture 66 are tailored to an x-ray film cassette in such a manner that this can be fully exposed by the x-ray radiation defined using the rectangular diaphragm aperture 66. To allow precise positioning of a respective diaphragm aperture 60, . . . , 66 as controlled by positioning facilities, positioning marks 21, 21′, 21″, . . . are provided on the periphery of the perforated disk 19. The position of each positioning mark 21, 21′, 21″, . . . correlates to the position of a respective diaphragm aperture 60, . . . , 66. The positioning marks 21, 21′, 21″, . . . enclose the same midpoint angles or arcs as the positions of the diaphragm apertures 60, . . . , 66. A specific position of a respective positioning mark 21, 21′, 21″, . . . corresponds to a specific position of the respectively associated diaphragm aperture 60, . . . , 66. This allows precise machine positioning. As shown in FIG. 3, the second perforated disk 22 is embodied in a similar manner to the first perforated disk 19 described above in FIG. 2 and can also be mounted in a rotatable manner in a central axis support 23. The second perforated disk 22 has a plurality of diaphragm apertures 40, . . . , 51 in differing sizes and positioning marks 24, 24′, 24″, . . . that correlate to the respective position. The individual sizes of the diaphragm apertures 40, . . . , 51 are shown schematically and can have diameters, for example, from 5 mm to 16 mm in 1 mm steps and can have a diameter of 30 mm for the largest diaphragm aperture 51. FIG. 4 shows a schematic top view of the interaction of the perforated disks 19 and 22, which are disposed in a mutually overlapping manner in the direction of the beam path in the radiation diaphragm 30. The perforated disks 19 and 22 should be disposed in the beam so that the midpoint of the mutual overlap of the two disks is disposed in the midpoint of the beam. In the rotation position shown in FIG. 4 the diaphragm aperture 60 of the perforated disk 19 and the diaphragm aperture 40 of the perforated disk 22 are positioned at the midpoint of the mutual overlap of the two disks. Since the diaphragm aperture 40 has the smaller diameter, it predetermines the contour and diameter of the x-ray radiation beam passing through it. The diaphragm aperture 40 is significance to the diaphragm setting actually achieved. In the embodiment of the perforated disks shown, the diaphragm apertures 41, 42, 43 and 44 of the perforated disk 22 have smaller diameters than the diaphragm aperture 60 of the perforated disk 19. With concentric positioning with the diaphragm aperture 60, the diaphragm apertures 41, 42, 43 and 44 of the perforated disk 22 would be respectively determining factors in respect of the effective diaphragm setting. FIG. 5 shows a positioning of the perforated disks 19 and 22. The diaphragm aperture 45 of the perforated disk 22 and the diaphragm aperture 60 of the perforated disk 19 are disposed at the midpoint of the overlap. The diaphragm aperture 60 has a smaller diameter compared with the diaphragm aperture 45 and is a determining factor for the x-ray beam passing through it. The diaphragm aperture 60 represents the effective diaphragm setting. FIG. 6 shows a further positioning of the perforated disks 19 and 22. The diaphragm apertures 51 and 64 are positioned at the midpoint of the x-ray beam. Because of its comparatively small diameter, the diaphragm aperture 64 is a determining factor for the effective diaphragm setting. FIG. 7 shows a further positioning of the perforated disks 19 and 22. The diaphragm apertures 51 and 66 are positioned at the midpoint of the x-ray beam. The rectangular diaphragm aperture 66, the contour and dimensions of which can, for example, be matched to an x-ray film cassette to be exposed, is disposed completely within the periphery of the diaphragm aperture 51 and has smaller dimensions than the diaphragm aperture 51. The rectangular diaphragm aperture 66 is a determining factor for the effective diaphragm setting. As shown in FIGS. 4 to 7 and described above, the selected distribution of the diaphragm sizes over the two perforated disks 19 and 22 and their mutual overlap allows an extremely compact structure of the diaphragm. The diaphragm ensures a wide diversity of variation of the possible effective diaphragm settings. The relatively dense arrangement of the diaphragm apertures 40, . . . , 51, 60, . . . , 66 on the respective perforated disks 19 and 22 in particular is clear, allowing efficient utilization of the respective perforated disk surface. The present embodiments relate to a radiation diaphragm 30 for an x-ray facility 1 with at least one radiation defining element, which is mounted in a displaceable manner and embodied as a perforated disk. The radiation defining element is mounted in a displaceable manner in a plane perpendicular to a beam to be defined 6 and has a plurality of differently formed diaphragm apertures 40, . . . 51, 60, . . . 66 for respectively differently contoured definition of the beam 6. The radiation defining element can, for example, be embodied as an essentially rotationally symmetrical perforated disk. In one embodiment, there are two radiation defining elements, which are disposed in a mutually overlapping manner in the direction of the beam to be defined 6. Various embodiments described herein can be used alone or in combination with one another. The forgoing detailed description has described only a few of the many possible implementations of the present invention. For this reason, this detailed description is intended by way of illustration, and not by way of limitation. It is only the following claims, including all equivalents that are intended to define the scope of this invention.
	description	This application is a continuation of U.S. patent application Ser. No. 12/710,602, filed Feb. 23, 2010, which is a continuation-in-part of U.S. patent application Ser. No. 12/706,690, filed Feb. 16, 2010, both of which are hereby incorporated by reference. The present invention relates to plasma igniters for inductively coupled plasma sources used in ion beam columns. Inductively coupled plasma (ICP) sources have advantages over other types of plasma sources when used with a focusing column to form a focused beam of charged particles, i.e., ions or electrons. The inductively coupled plasma source, such as the one described in U.S. Pat. No. 7,241,361, which is assigned to the assignee of the present invention, is capable of providing charged particles within a narrow energy range, which allows the particles to be focused to a small spot. ICP sources include a radio frequency (RF) antenna typically wrapped around a ceramic plasma chamber. The RF antenna provides energy to maintain the plasma within the chamber. The energy of ions used for ion beam processes is typically between 5 keV and 50 keV, and most typically about 30 keV. The electron energy varies between about 1 keV to 5 keV for a scanning electron microscope system to several hundred thousand electron volts for a transmission electron microscope system. The sample in a charged particle system is typically maintained at ground potential, with the source maintained at a large electrical potential, either positive or negative, depending on the particles used to form the beam. For the safety of operating personnel, it is necessary to electrically isolate the high voltage components. It is usually not possible to ignite a plasma in an ICP source by injection of the normal power level of the RF power used to drive the coil of the ICP source. This is because, in the absence of any initial ionization in the source chamber, the induced electrical field is usually not high enough to break down the gas atoms or molecules to create sufficient initial free charges. To generate this initial ionization, typically a high voltage pulse is required. In the prior art, a high voltage pulse to ignite the plasma in the ICP ion source has been initiated by contacting a Tesla coil to an electrode which is itself in direct electrical contact with the plasma chamber. The high voltage pulse induced by the Tesla coil then initiates a plasma which is subsequently sustained by the RF power from the ICP power supply. This plasma ignition method necessarily requires that there be direct electrical contact between some exterior electrode on the system and the interior of the vacuum system where the plasma is to be ignited. However, when the plasma is biased to high voltage for use as the source in a charged particle beam system, such a direct electrical contact would present serious safety concerns since the external connection would float up to the plasma potential at high voltage. Thus, it is generally not possible to provide such a direct external electrical contact to the plasma in an ICP ion source which is biased to high voltage for use as the source in an ion beam system. This electrical isolation of the high voltage plasma thus creates a problem for igniting the plasma in an ICP source used to generate a charged particle beam. An object of the invention is to provide a method for igniting a plasma in an ion beam system in which the ion source is biased to a high dc voltage. This invention is particularly suitable for use with an inductively coupled plasma source. The igniter preferably provides ignition energy through a source biasing electrode in the plasma source, and the igniter is preferably located near the plasma source to minimize the effects of cable capacitance between the igniter and the column. In a preferred embodiment, the output of the plasma igniter is a repetitive oscillatory voltage pulse which is efficiently coupled into the plasma chamber through an electrode which will be in contact with the plasma once it is ignited. In some embodiments, the plasma igniter is housed in a high voltage safety enclosure and is biased by the same power supply which controls the energy of the ions emitted by the ICP plasma source. The foregoing has outlined rather broadly the features and technical advantages of the present invention in order that the detailed description of the invention that follows may be better understood. Additional features and advantages of the invention will be described hereinafter. It should be appreciated by those skilled in the art that the conception and specific embodiments disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. It should also be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. To generate this initial ionization, typically a high voltage pulse is required. This pulse must be capacitively coupled into the source chamber where the gas is to be excited to generate a plasma. This requires that there be some means of connecting the voltage pulse from outside the vacuum system directly into the source chamber. In systems in which the plasma is biased to kilovolts dc voltage to serve as the source for an ion beam, it is difficult or impossible in the prior art to safely provide such an external contact to the plasma. Embodiments of the present invention provide an igniter for an inductively coupled plasma source for a charged particle beam system. This plasma igniter is preferably located near the inductively-coupled plasma (ICP) source to minimize the effects of cable capacitance between the igniter and the column. The output of the plasma igniter is a high voltage pulse which is efficiently coupled into the plasma chamber through an electrode which will be in contact with the plasma once it is ignited. A plasma sensor controls the plasma igniter, determining when a plasma has been initiated and then ceasing plasma igniter operation. The plasma igniter is housed in a high voltage safety enclosure and is biased by the same biasing power supply which controls the energy of the ions emitted by the ICP plasma source. FIG. 1 shows a prior art method for igniting a plasma comprising bringing a Tesla coil into contact with two alternative locations on the exterior of the charged particle beam system. The source chamber 102 may be an insulating vacuum enclosure fabricated from an insulating material such as ceramic, quartz, or Macor™ machinable ceramic. Requirements for optimum plasma containment in source chamber 102 include a low dielectric loss factor, high resistivity, vacuum compatibility, high thermal conductivity, and non-reactivity with the various feed gases used in plasma generation. Surrounding the source chamber 102 is an RF coil 104 connected to a match box 120 through electrical cables 116 and 118. Power from the RF supply 126 is coupled into the match box 120 by two electrical cables 122 and 124. Once even a small amount of ionization has been induced within the source chamber 102, an ionization cascade may progress, rapidly generating large numbers of free electrons and ions in the source chamber 102. In FIG. 1, a prior art charged particle ICP source 100 is shown. Gas feed line 128 connects through a regulator valve 130 to the feed line 132 which conducts the gas to be ionized into a capillary 134. The capillary reduces the feed gas pressure to the level inside the source chamber 102, and then conducts the feed gas into the source chamber 102. If feed line 128, regulator valve 130 and feed line 132 form a continuous electrically conducting path from outside the vacuum into the interior of the source chamber 102, a Tesla coil 140 may be momentarily connected (arrow 146) to line 128 to ignite a plasma within source chamber 102. The central high voltage wire 142 of the Tesla coil is surrounded by an external shield 144 for safety. Once a plasma has been ignited, Tesla coil 140 would then be removed from contact with feed line 128. The Source Biasing Electrode In order to utilize the plasma generated in the ICP source 100 as a source for ions in a focused ion beam (FIB) system, it is necessary to be able to apply an accelerating voltage to the ions as they emerge from the plasma and enter the FIB column. In both the prior art shown in FIG. 1, and in the present invention, a source biasing electrode 110 may be employed to apply the accelerating voltage to the ions. In FIG. 1, at the bottom of the ICP source, a source biasing electrode 110 is illustrated. A key requirement for the proper operation of the source biasing electrode is that there be direct contact between the plasma in the plasma chamber and one surface of the source biasing electrode, in other words, the source biasing electrode must form part of the enclosure for the plasma in order to be able to apply a voltage to the ions extracted from the plasma. In the examples cited herein, the source biasing electrode forms the lower portion of the plasma enclosure, however, other locations for the source biasing electrode are functionally equivalent within the scope of the present invention. The source biasing electrode 110 is connected through interior cable 112 to an external cable 114 which leads to a biasing power supply (not shown). Below the source biasing electrode 110, an extractor electrode 108 is positioned as part of the ion extraction optics. This biasing supply controls the energies of the charged particles emitted from the ICP source relative to ground potential. If the sample is at ground, this will then determine the final beam energy at the sample. Calculation of the Electrical Properties of the Source FIG. 2A illustrates the effective capacitances of the source chamber 202 and source biasing electrode 208 in an inductively coupled plasma source 200. The exterior of the source chamber 202 is surrounded by a split Faraday shield 214 which is grounded by a cable 216 and which prevents the voltage on the RF coil 104 (see FIG. 1) from capacitively coupling to the plasma. This coupling, if not prevented by the Faraday shield 214, would induce undesirable voltage fluctuations on the plasma potential which would induce chromatic aberrations in the charged particle column, thereby blurring the beam at the sample. Capacitance 218 is between the Faraday shield 214 and the interior wall of the source chamber 202. Capacitance 220 is between the interior wall of the source chamber 202 and the source biasing electrode 208, which is connected to the beam acceleration power supply (not shown) by cable 210. Capacitance 228 is between the cable 210 and ground. The feed gas to be ionized is fed into the source chamber 202 through orifice 204. The ion beam extracted from the plasma in the source chamber 202 emerges through orifice 212. Capacitance 222 is below the source chamber where there is no plasma generation. Any currents flowing in capacitance 222 due to the RF power are not effective in generating a plasma, thus it is desirable to minimize capacitance 222 by the design of the ICP source. Once a plasma has been ignited in the source chamber 202, capacitance 220 is essentially shorted by the plasma. FIG. 2B is a circuit diagram showing how the capacitances from FIG. 2A combine to form an effective source capacitance 250. Capacitances 220 and 218 are in series between the cable 210 and ground 216. Capacitances 222 and 228 appear in parallel with the series combination of capacitances 218 and 220. Thus the effective source capacitance 250 is:C250=C218C220/(C218+C220)+C222+C228,where only capacitance 220 has any effect on igniting a plasma, since capacitances 218, 222, and 228 are outside the plasma region. The same current 240 flows through both capacitances 218 and 220. The total current, I250, flowing through the effective source capacitance 250 is then:I250=I240+I242+I248.Since only the current I240 is effective in triggering a plasma, the efficiency of the plasma igniter depends on the fraction, FCurrent, of the total current, I250, flowing through the capacitance C220:FCurrent=I240/I250=I240/(I240+I242+I248).The total voltage across the effective source capacitance, V250, is then:V250=V218+V220=V222=V228,where voltage V218 is across capacitor C218, voltage V220 is across capacitor C220, voltage V222 is across capacitor C222, and voltage V228 is across capacitor C228. Capacitances 218 and 220 act as a capacitive voltage divider:V218=V250(1/C218)/(1/C218+1/C222).The next consideration is the power, PIgnition, from the plasma igniter which is effective in igniting a plasma in the source region with capacitance 220:PIgnition=V220I240.Obviously, for maximum plasma ignition efficiency, we want to maximize this power, PIgnition, as a fraction of the total power, PTotal, from the plasma igniter:PTotal=V250I250.Thus the plasma igniter power efficiency fraction, FPower, from the igniter that appears in the capacitance 220 where the plasma is to be ignited:FPower=PIgnition/PTotal=V220I240/V250I250. Clearly, then, in order to maximize the plasma igniter power efficiency fraction, FPower, we want to maximize both the voltage, V220, across capacitor 220 and the current, I240, through capacitor 220. In order to maximize the voltage across capacitor 220, we want to minimize the voltage, V218, across capacitor 218 which is in series with capacitor 220. To do this, it is necessary to maximize the value of capacitance 218, since the impendence of capacitor 218 goes as (1/C218). This may be accomplished by making the insulating walls of the plasma chamber 202 as thin as possible, and also by maximizing the dielectric constant of the plasma chamber walls. In order to maximize the current through capacitor 220, it is necessary to minimize the currents, I222 and I228, through capacitors 222 and 228, respectively. This may be accomplished by maximizing the impedances of capacitors 222 and 228. Since the impedances of capacitors 222 and 228 are proportional to 1/C222 and 1/C222, respectively, it is necessary to minimize the values of capacitances 222 and 228. For capacitance 222, capacitance minimization may be accomplished by proper design of the lower portion of the source, below the plasma region (see FIG. 2A). Reducing the areas and increasing spacings will both act to reduce C222. For capacitance 228, capacitance minimization may be accomplished by using an open wiring instead of shielded cables wherever possible, keeping safety considerations in mind and by making the distances between the open wires and neighboring grounded surfaces as large as possible. This analysis of the derivation of the effective source capacitance, C250, thus leads us to a design strategy for maximizing the power efficiency, FPower, of the plasma igniter. FIG. 3 is a simplified electrical schematic diagram 300 of a prior art plasma ignition circuit. The plasma igniter 306 is shown located away from the charged particle beam system employing the ICP source. Capacitance 302 corresponds to the internal capacitance of the source:C302=C222+C218C220/(C218+C220),where capacitances 218, 220 and 222 are from FIG. 2. This equation shows that capacitance 222 is in parallel with the series combination of capacitances 218 and 220. Any current in capacitance 222 thus can be seen to be taken away from the currents in capacitances 218 and 220 which are effective in igniting the plasma in the source chamber 202 in FIG. 2. Capacitance 304 is the cable capacitance between the plasma igniter 306 and the source chamber 202 in FIG. 2. Any currents in capacitance 304 are drawn away from the currents in capacitance 302 which go to the source:I302=(dV1/dt)C302/(C302+C304),where V1 represents the voltage on the secondary winding of the transformer used to couple the output of the plasma igniter into the source chamber—see FIGS. 7 and 8 for representative circuits illustrating this transformer coupling. The prior art circuit is referenced to ground 308. FIG. 3 thus illustrates the problem with prior art plasma ignition methods employing igniters located at a distance from the plasma source—a potentially large amount of the intended plasma ignition current may be siphoned away by the cable capacitance 304 and by any stray capacitances (such as capacitance 222 in FIG. 2) within the source which are outside the plasma region. The plasma ignition voltage must be increased to compensate for these losses, potentially leading to higher costs and inferior plasma ignition capabilities. For a source capacitance 302 of 25 pf and a cable capacitance of 500 pf, an output from the plasma igniter of 10 kV at 125 kHz was required, representing 4 A across the cable capacitance 304. Capacitances 302 and 304 thus appear in parallel across the output of the plasma igniter, with the larger cable capacitance 304 drawing proportionately more current than the smaller source capacitance 302. Since the ratio of capacitance 302 (25 pf) to the total capacitance (525 pf) is (25 pf)/(525 pf), only approximately 5% of the output current of the plasma igniter 306 is effective in plasma ignition. FIG. 4 is a simplified electrical schematic diagram 400 of a plasma igniter 408 located near the charged particle column as in the present invention. Again, capacitance 402 corresponds to the internal capacitance of the source:C402+C222+C218C220/(C218+C220),where capacitances 218, 220 and 222 are again from FIG. 2 and capacitance 222 is in parallel with the series combination of capacitances 218 and 220. Any current in capacitance 222 thus can be seen to be taken away from the currents in capacitances 218 and 220 which are effective in igniting the plasma in the source chamber 202 in FIG. 2. In the present invention, the plasma igniter 408 is located at or very near to the vacuum enclosure of the charged particle beam system employing the ICP source. Thus, the capacitance 404 of the cable connecting to the plasma biasing supply now appears in series with the source capacitance 402, instead of parallel as in the prior art in FIG. 3, thus the great majority of the voltage drop induced by the output, V1, of the plasma igniter 408 will appear across the source capacitance 402 instead of the cable capacitance 404. Impedance 410 corresponds to the internal resistivity (“dumping resistor”) of the biasing voltage supply. Capacitance 406 is the output capacitance of the biasing voltage supply, with a leakage resistance 412. Capacitance 404 is the cable capacitance between the plasma igniter 306 and the source chamber 202 in FIG. 2. V1 represents the voltage on the secondary winding of the transformer used to couple the output of the plasma igniter into the source chamber—see FIGS. 7 and 8 for representative circuits illustrating this transformer coupling. The circuit is referenced to ground 420. For a capacitance 402 of 25 pf and capacitance 404 of 500 pf, as in FIG. 3, then the output voltage V1 of the secondary winding of the transformer will be divided in the inverse ratio of the capacitances, thus more than 95% of V1 will appear across capacitance 402:V402=V1C402/(C402+C404) FIG. 5 is a diagram of a charged particle beam system 500 employing an in-line plasma igniter of the present invention. A vacuum enclosure 502 contains a charged particle column (not shown). At the top of the enclosure is a plasma sensor 552. Multiple methods for detecting the presence of a plasma are possible, including, for example, 1) the light from the plasma, 2) the drop in impedance due to ionization, 3) the change in the optimal tuning parameters in the RF match box, and 4) the temperature in the source chamber. When a plasma has been ignited, the dc bias voltage on cable 522 is equal to the output of biasing power supply 504, referenced to ground 506. The output 508 of bias power supply 504 is connected through shielded cable 510 to the input 512 of the plasma igniter 514, enclosed in safety housing 516. Thus, plasma igniter 514 may be biased to the high voltage output of biasing power supply 504 with no safety concern to the system operator. The output 518 of the plasma igniter 514 is connected through shielded cable 520 to interior cable 522 which connects to the source biasing electrode (not shown—see electrode 110 in FIG. 1). The plasma igniter 514 is preferably permanently physically connected to the cable 522, that is, it is not momentarily contacted and removed as a Tesla coil would be. While the plasma igniter 514 is permanently physically connected to the source biasing electrode, it can be electrically isolated, such as by a switch or software. The physical connection is “permanent” during normal use, but can be disconnected for maintenance. After the plasma has been ignited, the high voltage from supply 504 connects through the plasma igniter 514 to the source biasing electrode. Optionally, during plasma ignition, the high voltage output from supply 504 can be added to the pulsed high voltage from the plasma igniter 514 with the combined voltage going through interior cable 522 to the source biasing electrode (not shown). An extractor electrode (not shown) is connected and biased by power supply 540 through shielded exterior cable 544 to interior cable 542. A condenser electrode (not shown) is biased by power supply 530 through shielded cable 534 to interior cable 532. Both power supplies 530 and 540 are referenced to the high voltage output of power supply 504. The output from the plasma sensor is conducted to the logic circuitry 256 through signal line 554. Based on the signals from plasma detector 552, the logic circuitry 256 controls the plasma igniter 514 through control line 558. In general, the logic circuitry will activate the plasma igniter 514 until either a plasma has been initiated or the logic circuitry concludes that there is a defect which makes plasma initiation impossible. The igniter 514 is preferably part of a module such as those shown in FIGS. 7 and 8. A coupling network (FIG. 8) or high voltage transformer (FIG. 7) in the module selectively applies either the ignition voltage, the biasing voltage from biasing power supply, or both simultaneously. The length of the cable 520 from the igniter to the electrode is preferably less than 100 cm, more preferably less than 30 cm, and most preferably less than 15 cm. As discussed in FIG. 2B, above, the shorter cable 520, the lower its capacitance and the less power is required to deliver sufficient power through the cable to ignite the plasma. Also as discussed in FIG. 2B, it may be preferable that cable 520 is an open wire, not a shielded cable, in order to further reduce capacitance. The length of cable 510 is preferable less than 1000 cm, more preferably less than 500 cm, and most preferably less than 300 cm. Plasma Igniter Pulsed Voltage Waveform FIG. 6 shows the pulsed voltage waveform 600 used by the present invention to ignite a plasma in the ICP source. An oscillatory high voltage waveform 604 has a typical period 612 in the range 500 to 2 μs (2 to 500 kHz), with a preferred period in the range 10 to 3.33 μs (100 to 300 kHz). The oscillatory waveforms have a repetition rate 608 of roughly 100 Hz. To achieve a maximum plasma ignition voltage with reduced total power, a decaying 610 oscillatory waveform is used with an overall oscillatory period 606 in the range of 70 to 100 μs. The oscillatory period 606 is shown exaggerated with respect to the repetition period 608, as indicated by the break 620. In between oscillations, the output of the plasma igniter is 0 V, 602. Typical initial peak to peak voltages for the oscillatory waveforms are generally at least 1 kV, ranging up to 20 kV. A benefit of the decaying oscillatory pulse illustrated in FIG. 6 is that the initial voltage is maximized, while the total power per pulse is minimized by the decrease in voltage with the later cycles of the oscillation. FIG. 7 is a first exemplary electrical circuit for a plasma igniter according to the present invention. An inductively coupled ion source 702 has a capacitance 704, corresponding to capacitance 402 in FIG. 4. A high voltage isolation transformer 706 is mounted at or near to the ion source 702 at the exterior of a vacuum enclosure 768 containing the ion source 702 and having a vacuum feedthrough 762. Transformer 706 comprises a ground-referenced primary winding 710 and an isolated high voltage secondary winding 708. Primary winding 710 has a first connection point 786 and a second connection point 788. Secondary winding 708 has a first connection point 782 and a second connection point 784. Connection point 782 connects to the ion source 702 through vacuum feedthrough 762 in vacuum enclosure 768. The beam energy is set by the dc bias supply 722 with internal resistance 720 and output capacitance 718. The cable 726 between the dc bias supply 722 and the isolation transformer 706 has a capacitance 716 and a shield 712 referenced through electrical connection 714 to ground 724. Cable 726 is connected to connection point 784 of secondary winding 708. Connection point 782 connects the output of the secondary winding 708 to the ion source 702. Since the bias supply 722 has a dc output, the dc bias voltage generated by dc bias supply 722 passes through the secondary winding 708 with only a minor resistive voltage drop between connection points 784 and 782. A two-port oscillator 736 has a power supply 744 connected through wires 740 and 738, and is referenced to ground 742. The output of oscillator 736 is connected to the primary winding 710 of high voltage isolation transformer 706 through wires 732 and 734, which connect to primary winding 710 at connection points 788 and 786, respectively. An RF high voltage waveform, such as that illustrated in FIG. 6, is then inductively-coupled from the primary winding 710 into the secondary winding 708. The induced RF voltage on secondary winding 708 corresponds to voltage V1 in FIG. 4. The induced RF voltage on secondary winding 708 is coupled to the ion source 702 through connection point 782. A grounded safety enclosure 760 surrounds the two port oscillator 736 and transformer 760, as shown. The two port oscillator 736 is controlled by turning the power supply 744 on or off, based on a control signal received on line 764 from logic circuitry (not shown), such as logic circuitry 256 illustrated in FIG. 5. While power supply 744 is on, the two port oscillator 736 will generate a continuous pulsed waveform as shown in FIG. 6. FIG. 8 is a second exemplary electrical circuit for a plasma igniter according to the present invention. An inductively coupled ion source 802 has a capacitance 804, corresponding to capacitance 402 in FIG. 4. A high voltage coupling network 806 is mounted at or near to the ion source 802, at the exterior of a vacuum enclosure 868 containing the ion source 802, and having a vacuum feedthrough 862. The coupling network 806 comprises a high voltage choke 808 and a high voltage capacitor 810. High voltage choke 808 has a first connection point 884 and a second connection point 882. High voltage capacitor 810 has a first connection point 886 and a second connection point 882. Connection point 882 connects to the ion source 802 through vacuum feedthrough 862 in vacuum enclosure 868. The beam energy is set by the dc bias supply 822 with internal resistance 820 and output capacitance 818. The cable 826 between the dc bias supply 822 and the coupling network 806 has a capacitance 816 and a shield 812 referenced through electrical connection 814 to ground 824. Cable 826 is connected to connection point 884 of high voltage choke 808. Connection point 882 connects the output of the high voltage choke 808 to the ion source 802. Since the bias supply 822 has a dc output, the dc bias voltage generated by d bias supply 822 passes through the high voltage choke 808 with only a minor resistive voltage drop between connection points 884 and 882. A two-port oscillator 840 has a power supply 850 connected through wires 842 and 844, and is referenced to ground 846. The output of oscillator 840 is connected to the primary winding 832 of transformer 838 through wires 834 and 836. A high voltage pulse, such as that illustrated in FIG. 6, is then inductively-coupled to the secondary winding 830 of transformer 838. The induced RF voltage on secondary winding 830 is coupled through connection point 886. The RF voltage at connection point 886 is then capacitively-coupled through high voltage capacitor 810 to connection point 882 and then to ion source 802. The induced voltage on secondary winding 830 corresponds to voltage V1 in FIG. 4. A grounded safety enclosure 860 surrounds the two port oscillator 840, transformer 838, and coupling network 806 as shown. The two port oscillator 840 is controlled by turning the power supply 850 on or off, based on a control signal received on line 864 from logic circuitry (not shown), such as logic circuitry 256 illustrated in FIG. 5. While power supply 850 is on, the two port oscillator 840 will generate a continuous pulsed waveform as shown in FIG. 6. Focused Ion Beam System Employing the Plasma Igniter of the Invention FIG. 9 is a schematic diagram of a focused ion beam (FIB) system 900 of the present invention embodying a plasma igniter 950 with a power supply 925. An RF power supply 922 supplies RF power to a match box 920 which is connected to an antenna 904 which surrounds a plasma chamber 954 within which a plasma is generated. A feed gas to be ionized is fed into the plasma chamber 954 through a feed system 902. A biasing power supply 930 is connected through a plasma igniter 950 to a source biasing electrode 906 in the focused ion beam (FIB) column. An extractor electrode 908 in the FIB column is biased by a power supply 934, referenced to the output voltage of the biasing power supply 930. A condenser electrode 910 in the FIB column is biased by a power supply 932, referenced to the output voltage of the biasing power supply 930. Ions are extracted from the plasma contained in the plasma chamber 954 due to the high electric field induced at the lower end of the plasma chamber 954 by the bias voltage on the extractor electrode 908 relative to the voltage on the source biasing electrode 906. The ions extracted from the plasma chamber 954 emerge downwards through the opening in the source biasing electrode 906, forming an ion beam which enters the FIB column. Thus, the plasma at the lower end of the plasma chamber 954 serves as a “virtual source” for the FIB column. In general, a large portion of the ion beam going down the FIB column strikes one or more apertures in the column, such as apertures 906, 956, or 914. Because of the high mass and energy of the ions in the ion beam striking the apertures, erosion of apertures is a significant concern. Thus, the present invention comprises a number of aperture compositions that have low sputtering rates. Examples of materials which are most desirable for apertures include machinable carbon-based compounds, beryllium, vanadium, titanium, scandium, silicon, and niobium. Also included would be materials in which one or more of these elements or compounds comprise a major constituency of the overall material composition. Since the major area of aperture erosion tends to be the bore of the apertures where the incidence angle of the beam is far from normal to the local surface (i.e., the beam strikes the bore of the aperture at a “glancing” angle), aperture materials with low sputtering rates at non-normal incidence angles are of particular value. In the FIB column of FIG. 9, three apertures are shown: 1) an aperture in the source biasing electrode 906, 2) a beam acceptance aperture (BAA) 956, and 3) a beam defining aperture (BDA) 914. All three apertures 906, 956, and 914 are subject to the sputter erosion concerns addressed by the aperture material selection of the present invention. The position of the beam acceptance aperture 956 is controlled by the beam acceptance aperture actuator 936. The position and choice of beam defining aperture 914 is controlled by the beam defining aperture actuator 938. Two lenses 912 and 942 are shown forming a focused ion beam 960 on the surface of a sample 940 supported and moved by a sample stage 944 within a vacuum enclosure 946. The presence or absence of a plasma in the plasma chamber 954 is detected by a plasma detector 921. The signal from the plasma detector 921 is fed to the logic circuitry 924 as discussed in FIG. 5. The logic circuitry 924 controls the plasma igniter power supply 925, which, in turn, controls the plasma igniter 950 as discussed in FIGS. 7 and 8, above. The details of the plasma igniter circuits illustrated in FIGS. 7 and 8 are for exemplary purposes only—many other plasma igniter circuits are possible within the scope of the present invention. The waveform illustrated in FIG. 6 is also for exemplary purposes only—other waveforms are possible within the scope of the present invention. A preferred method or apparatus of the present invention has many novel aspects, and because the invention can be embodied in different methods or apparatuses for different purposes, not every aspect need be present in every embodiment. Moreover, many of the aspects of the described embodiments may be separately patentable or patented. For example, the types of low sputter materials used for the apertures and the dielectric material used for the plasma chamber may be separately patentable. Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made to the embodiments described herein without departing from the spirit and scope of the invention as defined by the appended claims. Moreover, the scope of the present application is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. As one of ordinary skill in the art will readily appreciate from the disclosure of the present invention, processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed that perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein may be utilized according to the present invention. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.
	abstract	A method, apparatus and computer product for modeling and analyzing performance of a Voice-over-IP (VoIP) configuration, composed of a plurality of components, is disclosed. The method comprises the step of representing selected ones of the plurality of components and relationships among the selected components, wherein said component representations are selected from the group of configuration non-specific representations consisting of: VoIP-DHCP Service, VoIP-CallOperation Service, VoIP_Signaling Service, VoIP_MediaGateway Service and VoIP_SIP Service, and wherein the representations of relationships are selected from the group of configuration non-specification representations consisting of: Hostedby/HostsServices and Integrates/IntegratedIn, providing a mapping between a plurality of first events and a plurality of second events occurring in the selected components, the mapping representing the relationships along which the first events propagate among the selected components, and determining at least one first event based on at least one of the plurality of second events by determining a measure between each of a plurality of relationship values associated with the plurality of first events and the plurality of second events.
052710491	abstract	A grid key for interior grid cells. A rectangular main body portion is bent near the middle at approximately a 90 degree angle. Two tabs that are flush with the main body portion extend outward in opposite directions from one end and along a portion of the length of the main body portion. The opposing side of the tabs is tapered at a 45 degree angle back toward the main body portion. The main body portion has a thickened section that coincides with the tabs. The thickened section is wedged between the soft stops of an individual interior grid cell to retract the stops and allow loading of a fuel rod.
	abstract	A method of using an ICF chamber may include causing a target in the ICF chamber to emit x-ray radiation; receiving the x-ray radiation through a plurality of holes in a wall of the ICF chamber; and absorbing the x-ray radiation in a gas contained in a plurality of tubes that are coupled to the plurality of holes.
050935798	description	DESCRIPTION OF THE PREFERRED EMBODIMENTS Before explaining the operation of the present invention, the temperature rise in a mask during exposure will first be described. If in FIG. 1, the back of the wafer chuck 6 is maintained at a certain temperature T.sub.0 by means of constant temperature circulating water, at different sites x.sub.0 -x.sub.3 such as shown in FIG. 2B, the temperatures are such as shown in FIG. 2A wherein the axis of the abscissa denotes the position x while the axis of the ordinate denotes the temperature. As regards the position x, as seen in FIG. 2B, a predetermined position on the constant temperature water side (back face) of the wafer chuck 6 is taken as an origin and, along the direction of irradiation of exposure energy (X-rays 1) to a mask 4 and a wafer 5, the interface between the wafer chuck 6 and the wafer 5 is denoted by x.sub.1, the front face of the wafer 5 is denoted by x.sub.2 and the position of the mask substrate 4 is denoted by x.sub.3. As seen in FIG. 2A, at the interface x.sub.1 between the wafer 5 and the wafer chuck 6, there is an interruption in the temperature. This is because of the presence of the contact thermal resistance between the wafer 5 and the wafer chuck 6. The temperature rise .DELTA.T (=T.sub.3 -T.sub.0) in the mask 4 being exposed with the X-rays 1, for example, is given by the following equation: EQU .DELTA.T=(tc/.lambda.c+R+tw/.lambda.w+g/.lambda.g)Qt . . . (1) where tc is the thickness of the wafer chuck 6 with respect to the direction of irradiation, .lambda.c is the heat conductivity of the wafer chuck, tw is the thickness of the wafer 5 with respect to the direction of irradiation, .lambda.w is the heat conductivity of the wafer, g is the proximity gap between the mask 4 and the wafer 5 with respect to the direction of irradiation, .lambda.g is the heat conductivity of the gas in the proximity gap, and R is the contact thermal resistance between the wafer chuck 6 and the wafer 5. Also, Qt is the strength of the X-rays 1 (FIG. 1) as projected to the mask 4 per unit time and unit area. The thermal distortion .DELTA.1 of the mask 4 resulting from the temperature rise can be expressed by using a linear expansion coefficient .alpha. and the exposure view angle 21 (which corresponds to the range for the pattern of the mask 4 to be transferred to the wafer), in the following manner: EQU .DELTA.1=1.multidot..alpha..DELTA.T . . . (2) Here, using a silicon nitride (Si.sub.3 N.sub.4) mask having a linear expansion coefficient .alpha. (.alpha.=2.7.times.10.sup.-6 [1/deg]) and a view angle 30 mm (1=15 mm in a He gas ambience and under the conditions shown in Table 1, below, the thermal distortion in the exposure will now be considered. TABLE 1 ______________________________________ Proximity Gap g = 10 microns Wafer Chuck (material: SUS) .lambda.c = 0.245 [W/cm .multidot. deg] tc = 0.2 cm Si Wafer .lambda.w = 0.84 [W/cm .multidot. deg] tw = 0.05 cm X-ray Strength Qt = 0.1 [W/cm.sup.2 ] ______________________________________ First, by using FIG. 3, a temperature rise .DELTA.T on an occasion when the interspace between the wafer chuck 6 and the wafer 5 is uncontrollably evacuated as in the FIG. 5 example, will be determined. FIG. 3 illustrates the contact thermal resistance on an occasion when He gas or air is confined within a small interspace between the wafer 5 and the wafer chuck 6 (substrate holding table), wherein the axis of the abscissa denotes the pressure in the small interspace while the axis of the ordinate denotes the contact thermal resistance. In this case, the pressure difference between both sides of the wafer 5 produced by the vacuum supplied to the wafer chuck 6 is set to be equal to 150 Torr. It is seen in FIG. 5 that, when the minute space between the wafer chuck and the wafer is maintained at complete vacuum, the contact thermal resistance R is equal to 10.sup.2 Kcm.sup.2 /W. When this value and the exposure conditions mentioned above are substituted into equation (1), then the following results: EQU .DELTA.T.apprxeq.10 (deg) Accordingly, from equation (2), the thermal distortion .DELTA.1 is 0.81 micron. It is considered that the maximum tolerable thermal distortion is 0.025 micron when the alignment precision is 0.06 micron, and the aforementioned value is extraordinarily greater than this. Next, description will be made of the principle of operation of the present invention. According to the present invention, for exposure of a mask 4 and a wafer 5, as seen in FIG. 1, the gas in a reduced pressure duct 11 is drawn by a drawing pump 17, such that the pressure in the clearance between the wafer 5 and the wafer chuck 6 is reduced. This produces a pressure difference between both sides of the wafer 5, by which the wafer 5 is attracted to and held on the wafer chuck 6. In this instance, the pressure in the reduced pressure duct 11 is controlled on the basis of the measurement through a pressure gauge 13a so as to maintain the contact thermal resistance between the wafer 5 and the wafer chuck 6 at a predetermined value. Such a predetermined value for the contact thermal resistance is set to ensure that the heat in the wafer 5 is discharged to prevent a temperature rise of the wafer 5 thereby avoiding a avoid temperature rise in the mask 4, such that the pattern of the mask 4 can be printed on the wafer 5 correctly. The contact thermal resistance R can be written from the thermal distortion tolerance .DELTA.1.sub.0 and from equations (1) and (2), as follows: EQU R.ltoreq.(.DELTA.10)/(1.multidot..alpha.).multidot.1/Qt-(tc/.lambda.c+tw/.l ambda.w+g/.lambda.g) . . . (3) Substituting the exposure conditions set forth in Table 1 into equation (3), it follows that: EQU R.ltoreq.4.6 [deg.multidot.cm.sup.2 /W) It is seen from FIG. 3 that the pressure in the clearance between the wafer 5 and the wafer chuck 6 which produces contact thermal resistance R of not greater than 4.6 (deg.multidot.cm.sup.2 /W), is approximately not less than 50 Torr. As described, in the present invention, the pressure in the space between the wafer chuck 6 and the bottom surface of the wafer 5 is not uncontrollably evacuated by a pump but, rather, a particular pressure that does not produce a large contact thermal resistance, causing inconveniences, is retained controllably. Such a pressure can vary depending on the exposure conditions. For example, if the proximity gap of the exposure conditions in Table 1 is 50 microns, then R.ltoreq.1.01 [deg.multidot.cm.sup.2 /W] and, thus, the pressure should be not less than 200 Torr. It is to be noted here that the pressure difference between both sides of the wafer 5 has to be sufficient for the holding of the wafer 5 by the wafer chuck 6 and, to this end, the pressure to be applied to the front surface of the wafer is controlled as required, simultaneously with the control of the pressure in the reduced pressure duct 11 of the wafer chuck 6. Approximately, a pressure difference not less than 100-150 Torr is necessary. Referring back to FIG. 1, there is shown an X-ray exposure apparatus to which an embodiment of the present invention is applied. In FIG. 1, denoted at 1 are X-rays as produced by an accumulating ring or the like, not shown; at 3 is a chamber the inside of which is occupied by a gas such as He, for example, transmissive to the X-rays 1, wherein the X-rays 1 pass through a beryllium (Be) window 2 and enter into the chamber 3; at 4 is a mask; at 5 is a wafer onto which a pattern formed on the mask 4 is to be printed through the exposure to the X-rays 1; at 6 is a wafer chuck for holding the wafer 5 by attraction; at 7 is a passageway which is formed in the wafer chuck 6 and through which constant temperature water circulates to maintain the temperature of the wafer chuck 6 constant. The passageway 7 communicates with an outlet port 9 from which the constant temperature water flows into a constant temperature vessel 10 and, after being adjusted to a predetermined temperature, the water flows again into the passageway 7 from an inlet port 8. By this circulation, the wafer chuck 6 can be maintained at a constant temperature. Further, the wafer chuck 6 is provided with a reduced pressure duct 11 the holding the wafer 5. The reduced pressure duct 11 communicates with a pressure gauge 13a through a drawing duct 12 and, also, the reduced pressure duct communicates with a vacuum supplying pump 17 and a He gas supplying tank 16a through gas adjusting valves 15a and 15b, respectively. The quantity of gas supply to the reduced pressure duct 11 can be determined by the degree of opening/closing of each of the adjusting valves 15a and 15b. A signal corresponding to a pressure value measured by the pressure gauge 13a is applied to a central processing unit (CPU) 20. On the basis of the signal from the controller 14a, in response to which the controller 14a controls the opening/closing of the gas adjusting valves 15a and 15b, by which the pressure in the reduced pressure duct 11 can be maintained at a predetermined value (for example, 50 Torr). Namely, the contact thermal resistance between the wafer 5 and the wafer chuck 6 is maintained at a desired value. Similarly, the He gas pressure in the chamber 3 is maintained constant by controlling the opening/closing of the gas adjusting valve 15c through the controller 14b in response to a signal from another pressure gauge 13b, measuring the pressure within the chamber 3, applied to the CPU 20, namely, by controlling the quantity of the He gas supplied to the chamber 3 from the tank 16b. In this embodiment, first the CPU 20 calculates and determines the pressure to be established in the reduced pressure duct 11 on the basis of various data, such as those shown in Table 1 and FIG. 3, as inputted into a memory of the CPU 20 beforehand, and on of the three equations mentioned above. It is to be noted that those data based on the specification of the exposure apparatus and the state of exposure, necessary for these three equations for calculation of the contract thermal resistance R, are inputted into the CPU 20 beforehand. The pressure in the reduced pressure duct 11 is different, depending on the pressure difference between both sides of the wafer 5 and the material of the wafer chuck 6. For example, if the pressure difference is 150 Torr and the wafer chuck 6 is made of an SUS material, from FIG. 3 the pressure to be provided in the reduced pressure duct 11 is determined to be equal to about 50 Torr, and the gas adjusting valves 15a and 15b are opened/closed so as to maintain the determined pressure. The He gas pressure in the chamber 3 is determined to be equal to 200 Torr which corresponds to the sum of the pressure of 50 Torr in the reduced pressure duct 11 and the pressure difference of 150 Torr for the holding of the wafer 5. Similar to the pressure control of the reduced pressure duct 11, the He gas pressure is controlled to be maintained at the determined pressure, by means of the gas adjusting valve 15c. As regards the contact thermal resistance R, there are cases wherein the resistance changes not only with the pressure Pn of the gas in the reduced pressure duct 11 but also with the flatness of the wafer 5 and/or the material of the wafer chuck 6. Further, since the contact thermal resistance R to be set changes with the strength of the X-rays 1 or the like, also in this respect, it is necessary to adjust the pressure Pn of the reduced pressure duct 11. When the pressure Pn of the reduced pressure duct 11 is changed in accordance with the conditions and if the pressure difference Pw for the holding of the wafer 5 by the wafer chuck 6 is to be unchanged, the ambience pressure Pc (=Pn+Pw) in the chamber 3 changes with the change in the pressure Pn. However, if the pressure Pc in the chamber 3 changes, the transmission factor to the X-rays 1 passing therethrough changes. Thus, there is a possibility that a desired exposure amount is not obtained at the time of exposure of the wafer 5 to the mask 4. In order to avoid this, the following two methods may be adopted. (1) The first is that: the exposure time of the mask 4 and the wafer 5 to the X-rays 1 is changed in accordance with the X-ray transmission factor or the pressure Pc in the chamber 3 as measured by the pressure gauge 13b. The exposure time can be changed by means of a shutter (not shown), for example, provided at an upstream side of the mask 4. (2) The second is that: when a maximum of the pressure Pn to be established in the reduced pressure duct 11 in accordance with various exposure conditions is denoted by P.sub.(n-Mx), the pressure Pc in the chamber 3 is set so as to satisfy the following relation: EQU Pc=Pw+P.sub.(n-Mx) or Pc>Pw+P.sub.(h-Mx) If this is done, the pressure Pc in the chamber 3 can be maintained constant even if the pressure Pn of the reduced pressure duct 11 changes with the exposure conditions. As a result, a desired exposure amount is always obtainable. It will be understood from the foregoing that an important feature of the present invention resides in that a gas which serves as a heat conducting medium is present between the wafer 5 and the wafer chuck 6, at a predetermined pressure. Thus, the He tank 16a in FIG. 1 is not always necessary. The structure may be modified such as shown in FIG. 4, for example, wherein the drawing duct 12 is coupled to a switching valve 18, a gas adjusting valve 15a and a pump 17 in this order, such that by increasing the restriction conductance of the gas adjusting valve 15a, the pressure in the reduced pressure duct 11 is maintained at a desired value. In this example, by switching the valve 18, the reduced pressure duct 11 can be communicated with the chamber 3 whereby the reduced pressure duct 11 and the chamber 3 can be maintained at the same pressure. Thus, the wafer 5 can be easily unloaded from the wafer chuck 6. Also, while in the above-described embodiment the pressure gauge 13a for measurement of the pressure (vacuum level) of the reduced pressure duct 11 is coupled to the conduit 12 for the gas supplying system or the gas discharging system, the piping for the pressure gauge 13a may be separated from the conduit 12, such that the pressure in the reduced pressure duct 11 may be measured without intervention of the conduit 12. On that occasion, the pressure gauge 13a can measure the pressure of the reduced pressure duct 11 without being affected by the conductance of the conduit 12, for example, and therefore, a more accurate measurement is possible. Further, it is not necessary that the pressure in the chamber 3 is maintained at a reduced pressure of 200 Torr as mentioned hereinbefore. It is sufficient that the pressure difference between both sides of the wafer 5 is enough to hold the wafer 5. Thus, the pressure may be equal to or higher than the atmospheric pressure. While, in the foregoing, description has been made of an example wherein the invention is applied to an exposure apparatus, the applicability of the invention is not limited to such field. Rather, the invention is widely applicable to various apparatuses wherein a sample is to be maintained at a constant temperature and wherein the sample is to be held by using an attracting force resulting from a pressure difference produced between both sides of the sample. In accordance with the present invention, as described hereinbefore, the pressure in the space between a bottom surface of a substrate and a substrate holding table is not uncontrollably evacuated but, rather, a particular pressure that does not produce a large contact thermal resistance, causing various inconveniences, is positively and controllably retained. As a result, it is possible to suppress a temperature rise of the substrate. While the invention has been described wit reference to the structures disclosed herein, it is not confined to the details set forth and this application is intended to cover such modifications or changes as may come within the purposes of the improvements or the scope of the following claims.
039393534	claims	1. In an electron microscope having a specimen chamber evacuated during use of the microscope, an electron beam operative during use of the microscope to irradiate a portion of a specimen and an electron lens for focusing the beam, an apparatus for adjustability and releasably mounting a specimen to undergo irradiation during use of the microscope and for substantially reducing the effect of vibration on the focusing of the beam, said apparatus comprising: specimen-holding means positionable into an irradiating position wherein a portion of the specimen is exposed to the electron beam and including means for adjustably positioning the specimen when said specimen-holding means is in said irradiating position to variably select the portion of the specimen exposed to the electron beam, means for releasably mounting said specimen-holding means in said irradiating position, and means for rigidly releasably coupling said specimen-holding means to the electron lens when said specimen-holding means is in said irradiating position, said means for releasably mounting said specimen-holding means comprising, a cylindrical support member having a pair of opposed end surfaces and a lateral surface, means mounting said specimen-holding means at one of said end surfaces, means defining a circumferential shoulder on a portion of said lateral surface, and means defining an annular recess in said lateral surface circumferentially of said lateral surface, means defining a throughbore between the interior and the exterior of said specimen chamber for receiving said cylindrical support member, said means defining a throughbore including means defining a second shoulder in a wall of said specimen chamber for engaging with said circumferential shoulder on said lateral surface of said cylindrical support member when said cylindrical support member is disposed within said throughbore, and means disposed within said annular recess hermetically sealing said cylindrical support member in said throughbore, said cylindrical support member having one of said opposed end surfaces exposed to the interior and exterior of said specimen chamber respectively whereby said cylindrical support member is forced toward the interior of said specimen chamber whenever a pressure differential is developed between the interior and the exterior of said specimen chamber to engage said shoulders for rigidly releasably coupling said specimen-holding means by said cylindrical support member to the electron lens to transmit vibratory motion from said specimen-holding means to the lens to substantially prevent the relative movement of one with respect to the other whenever said specimen-holding means is induced to vibrate thereby maintaining the focus of the electron beam on the selected portion of the specimen. 2. In an electron microscope according to claim 1, wherein said specimen-holding means comprises a rotable, elongated cylindrical member having means disposed at one end portion thereof for mounting the specimen and wherein said cylindrical support member includes means defining a throughbore parallel to main axis of said cylindrical support member for receiving said elongated member therein for adjustable rotational movement about the longitudinal axis thereof. 3. In an electron microscope according to claim 2, wherein said throughbore has an axis parallel to said main axis and disposed eccentrically thereof, and wherein said means for adjustably positioning the specimen further comprises means mounting the support member for adjustable rotational movement about said main axis. 4. In an electron microscope according to claim 1, wherein said means for coupling comprises means for forcibly abutting a portion of said specimen-holding means on the electron lens. 5. In an electron microscope according to claim 1, wherein said means for coupling comprises a rigid intermediate member contacting the electron lens, and means for forcibly abutting a portion of said specimen-holding means on said intermediate member. 6. In an electron microscope according to claim 1, wherein said means for releasably mounting said specimen-holding means comprises means defining an evacuatable specimen chamber receptive of a negative pressure applied thereto and having means therein defining a throughbore for fluid tightly receiving said specimen-holding means, whereby said specimen-holding means is forced towards said chamber whenever a pressure differential is developed between said chamber and the atmosphere. 7. In an electron microscope according to claim 1, further comprising indicating means for indicating the relative position of the specimen thereby indicating the portion of the specimen exposed to the electron beam.
	claims	1. An apparatus for imaging a first material of a device, the device comprising said first material and a second material, said apparatus comprising: a source of x-rays; a filter for receiving x-rays from the source of x-rays and allowing transmission of x-rays therethrough to the device; the filter material having an atomic number greater than the atomic number of the first material; and an x-ray detector for receiving x-rays from the device. 2. The apparatus of claim 1 wherein the second material is semiconductor material. claim 1 3. The apparatus of claim 2 wherein the semiconductor material comprises silicon. claim 2 4. The apparatus of claim 3 wherein the silicon contains an active region. claim 3 5. The apparatus of claim 4 wherein the first material comprises copper. claim 4 6. The apparatus of claim 5 wherein the filter material has an atomic number in the range of from 30 to 35 inclusively. claim 5 7. The apparatus of claim 6 wherein the filter material comprises zinc. claim 6 8. An apparatus for imaging a first material of a device, the device comprising copper and a second material, said apparatus comprising: a source of x-rays; a filter for receiving x-rays from the source of x-rays and allowing transmission of x-rays therethrough to the device; the filter material having an atomic number greater than the atomic number of copper; and an x-ray detector for receiving x-rays from the device. 9. The apparatus of claim 8 wherein the second material comprises silicon. claim 8 10. The apparatus of claim 9 wherein the silicon contains an active region. claim 9 11. The apparatus of claim 10 wherein the filter material has an atomic number in the range of from 30 to 35 inclusively. claim 10 12. The apparatus of claim 11 wherein the filter material comprises zinc. claim 11 13. The apparatus of claim 12 wherein the device comprises a third material comprising lead. claim 12 14. The apparatus of claim 12 wherein the device comprises a third material comprising tin. claim 12 15. The apparatus of claim 12 wherein the device comprises a third material comprising a lead/tin mixture. claim 12
	description	This application claims benefit of Japanese Application No. 2006-142315 filed in Japan on May 23, 2006, the contents of which are incorporated by this reference. The present invention relates generally to an optical substance manipulator, and more particularly to an optical substance manipulator harnessing the principles of optical tweezers, which are applied to some fields such as biochemical, molecular mechanics and micro•nanoscale thermofluid engineering fields. Optical substance manipulation techniques represented by an optical tweezers device are capable of manipulating a microscale substance in a non-contact, non-destructive fashion. There is an optical tweezers technique extensively put into practical use, in which light is tightly focused by an objective lens or the like into a medium such as a solution or air, so that a substance (particles) can be picked up near the focus of incident light by virtue of light pressure occurring at the substance interface in the medium (see Non-Patent Publication 1). The optical tweezers technique is capable of picking up a substance in a non-contact way, and manipulating the captured subject three-dimensionally with a micrometric order resolving power. For this reason, there has been much achieved through its use as an experimental tool that applies any desired manipulation to a subject of sub-microscopic size such as a single cell or DNA to go deep into what happens chemically and biologically (Non-Patent Publication 2). As one example, there is the result so far reported of using optical tweezers to take hold of and manipulate microscopic particles added to both terminus of a string form of a single molecule, thereby making a knot across the molecular and measuring a tension change (Non-Patent Publication 3). The optical substance manipulation techniques used so far in the art, for the most part, make use of laser light obtained by entering parallel light in a collective lens such as an objective lens to focus that light onto one point. With this method, strong manipulation force is obtainable because the light is focused with high intensity; however, there is the scope of action narrowing down to a few micrometers for that. Further, the directionality of manipulation force resulting from light pressure is only limited to that of trapping force toward, or repulsive force off, the laser focus. For this reason, a substance of micrometer order is manipulated by a method wherein once that substance has been trapped at the focus, the whole ambient medium or the whole laser irradiation system is moved to transfer the substance. This method works very favorably for moving a single substance to any desired position; however, it renders it difficult to apply extensive manipulation, continuous manipulation, and fast manipulation to a group of massive substances scattered in the medium. In recent years, an idea for making up for the narrowness of the range of action of the optical tweezers technique has been proposed: there are a number of laser irradiation areas formed in a medium as by locating a special diffraction grating or the like in a laser light path to split a laser beam into multiple beams, so that multiple substances can be manipulated simultaneously (Non-Patent Publication 4, and Patent Publications 1 and 2). Also, it has been reported that by locating a cylindrical lens or the like in an optical path, the laser focus is so transformed that multiple substances can be trapped linearly (Non-Patent Publication 5). With these methods, it is true that the amount of concurrently manipulatable substances can be increased; however, they are similar to the prior art in terms of light pressure being used as a substance trapping force, and so are used mainly for substance manipulation after trapping. To enable continuous manipulation without taking hold of a substance, it is necessary to continue to apply continued force of action to a moving substance. For instance, if a subject group of substances is in a constantly flowing state, continuous manipulation is enabled even with trapping force as light pressure. In this regard, there is a continuous manipulation method proposed, using multi-point optical tweezers using a diffraction grating (Non-Patent Publications 6 and 7, and Patent Publication 1). However, the performance of action would vary largely depending on the flowing conditions for substances. In addition, this method is inefficient because the margin of substance manipulation is narrow relative to the range of substantial light irradiation. Patent Publication 1 JP2005-502482A Patent Publication 2 JP2005-515878A Non-Patent Publication 1 Hiroo Ukita, “Micromechanical Photonics—Applications of Optical Information Systems”, pp. 61 (published by Morikita Shuppan Co., Ltd., 2002, 9) Non-Patent Publication 2 Ashkin, A., IEEE Journal of Selected Topics in Quantum Electronics, Vol. 6, pp. 841-856, (2000) Non-Patent Publication 3 Arai, Y., et al., Nature, Vol. 399, pp. 446-448, (1999) Non-Patent Publication 4 Grier, D. G., Nature, Vol. 424, pp. 810-816, (2003) Non-Patent Publication 5 Dasgupta, R., et al., Biotechnology Letters, 25, Pp. 1625-1628, (2003) Non-Patent Publication 6 Korda, P. T., et al., Physical Review Letters, Vol. 89, No. 12, 128301, (2002) Non-Patent Publication 7 MacDonald, M. P., et al., Nature, Vol. 426, pp. 421-424, (2003) The prior art situations being like this, the present invention has for its object the provision of an optical substance manipulator capable of continuing to apply a continued force of action to moving substances without being limited by the flowing conditions for the substances yet with a wide manipulation margin and with efficiency, thereby continuously carrying out various manipulations such as separation, concentration, mixing, and deflection. According to the invention, that object is achieved by the provision of an optical substance manipulator capable of manipulating microscopic particles dispersed in a flowing fluid by means of light pressure, characterized by comprising an optical system that forms multiple linear light-collective areas simultaneously with respect to a fluid that flows on a subject surface, and further comprising, in optical path forming the respective linear light-collective areas, means adapted to adjust the directions of the linear light-collective areas on the subject surface and means adapted to adjust the positions of the linear light-collective areas. Preferably in this case, that means adapted to adjust the directions of the linear light-collective areas is a cylindrical lens or mirror adjustable in terms of rotation. Similarly, it is preferred that the means adapted to adjust the positions of the linear light-collective areas comprises an optical element adjustable in terms of position and angle. It is also preferred that the aforesaid optical system works splitting light coming out of one light source into two or more and synthesizing light after passing through the means adapted to adjust the directions of the linear light-collective areas and the means adapted to adjust the positions of the linear light-collective areas. It is further preferred that there are two linear light-collective areas formed, and the aforesaid optical system comprises a light splitter means adapted to split light coming out of one light source into two, means adapted to adjust the directions of the linear light-collective areas, means adapted to adjust the positions of the linear light-collective areas, and light synthesis means adapted to synthesize the light split into two. The optical substance manipulator of the invention provides a non-contact type substance manipulation system that harnesses laser radiation pressure with an improved degree of flexibility in the ability to manipulate subjects. As compared with the prior optical tweezers art, the invention makes it easier to implement a bulk of manipulations for a group of substances scattered over an extensive range: it is possible to manipulate cells and DNAs in large quantities and in continuous fashions. The invention, because of manipulating substances without fixing them to one site, also allows for continued manipulations of substances flowing in a microscopic flowing topology represented by microchemical chips. With the invention harnessing non-destructive laser light, it is further possible to manipulate biological substances while keeping them intact. Furthermore, the invention allows for localized manipulation limited to the laser irradiation range, making a lot of contributions to the development of technology toward the integration of functions on chips for DNA analysis and chemical synthesis. In addition, the optical substance manipulator of the invention can be additionally attached to an optical microscope, and so has high general versatility with sample vessels. Thus, the inventive optical substance manipulator can implement various substance manipulations on the same system without recourse to any exclusive diffraction gratings, etc., and so would have a lot more applications in a lot more fields, and ever higher versatilities as well. Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification. The invention accordingly comprises the features of construction, combinations of elements, and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims. The optical substance manipulator of the invention is, now explained with references to one preferred embodiment. FIG. 1 is illustrative in schematic (perspective) of the construction of one embodiment of the optical substance manipulator. For a better understanding of explanation, coordinate axes X, Y and Z are determined as shown. Linearly polarized laser light oscillated from a light source laser 1 (e.g., a near infrared Nd:YAG laser of 1,064 nm in wavelength) is expanded in beam diameter at a beam expander made up of a negative lens L1 and a positive lens L2 confocal with each other, incident on a half-wave plate λ/2 at which its direction of polarization is rotated in a given direction. Then, the light enters the first polarization beam splitter BS1 at which it is split into two components: a component polarized in the Z direction (hereinafter called p-polarized light) and a component polarized in the XY direction (similarly s-polarized light). The p-polarized light component travels toward a mirror M1 through the first polarizing beam splitter BS1 while the s-polarized light propagates to ward a mirror M2 upon reflection at the first polarizing beam splitter BS1. The respective beams go from the first polarizing beam splitter BS1 through cylindrical lenses CL1 and CL2 located before the mirrors M1 and M2 in an optical path, and are reflected at the mirrors M1 and M2, arriving at the second polarizing beam splitter BS2. Here, the s-polarized light component alone is reflected while the p-polarized light component passes through; both the beams travel in the Y-axis direction. Two such beams are expanded in beam diameter by positive lenses L3 and L4 confocal with each other, arriving at a mirror M3; however, a quarter-wave plate λ/4 interposed between the positive lenses L3 and L4 turns them into circularly polarized light. The laser light reflected by the mirror M3 in the X-axis direction enters a filter box 2 built in an inverted microscope. The two beams are reflected in the Z-axis direction by the first dichroic mirror DM1 located in the filter box 2 and has the property of transmitting visible light and reflecting light in the near infrared range. The two beams then enter an infinity correction oil immersion objective lens Ob mounted on the microscope where they are collected, entering a subject in a flow passage 5 through a microchannel MC via an oil immersion oil. Note here that there is a mercury lamp 3 located to illuminate the subject in the flow passage 5 through the microchannel MC; that is, illumination light from that mercury lamp 3 is reflected off the second dichroic mirror DM2 located on a viewing side with respect to the first dichroic mirror DM1, and enters the objective lens Ob through the first dichroic mirror DM1 where it is collected to illuminate the subject. A fluorescent image of the subject in the flow passage through the micro-channel MC, magnified by the objective lens Ob, is taken by a photographic camera 4 through the first and second dichroic mirrors DM1 and DM2. That image is displayed, and recorded. The half-wave plate λ/2 here is adjustable in terms of rotation about the optical axis (X-axis) so that the direction of linearly polarized light oscillated from the laser 1 is adjustable. By that adjustment, it is possible to adjust the proportion of the p- and s-polarized light components incident on the first polarizing beam splitter BS1. Why the two beams are turned by the quarter-wave plate λ/4 into circularly polarized light for incidence on the subject is to hold back the generation of unwanted interference fringes. The positions of mirrors M1 and M2 are adjustable in the direction of propagation of the respective beams (the mirror M1 for the X-axis direction, and the mirror M2 for the Y-axis direction), and the angles of mirrors M1 and M2 are adjustable about the Z-axis and the direction of propagation of each beam (the mirror M1 about the X-axis and the mirror M2 about the Y-axis), respectively. Further, the position of mirror M3 is adjustable in the direction of propagation of the beam (the Y-axis direction), and the rotation of cylindrical lenses CL1 and CL2 about the X- and Y-axes, respectively, is adjustable as well. FIG. 2 is a taken-apart view of one optical path from the laser 1 of the optical substance manipulator of FIG. 1 via the first polarizing beam splitter BS1, the cylindrical lens CL1 and the second polarizing beam splitter BS2 as far as a focal plane F (subject surface) in the flow passage through the microchannel MC, and the same applies to another optical path through the cylindrical lens CL2, too. To be more specific, FIG. 2(a) is a taken-apart view of the optical path in a section along the generator of the cylindrical lens CL1, and FIG. 2(b) is a taken-apart view of the optical path in a section orthogonal to that generator. In FIGS. 2(a) and 2(b), the focal length of each lens and inter-lens distances are given in mm. In the section of FIG. 2(a) where the refracting power of the cylindrical lens CL1 (CL2) does not work, parallel light oscillated from the laser 1 is expanded in beam diameter by the beam expander made up of the negative lens L1 and the positive lens L2. The parallel light with an expanded beam diameter goes through the half-wave plate λ/2, the first polarizing beam splitter BS1, the cylindrical lens CL1 (CL2), the mirror M1 (M2) and the second polarizing beam splitter BS2, and is expanded in beam diameter through the positive lenses L3 and L4 confocal with each other with the quarter-wave plate λ/4 interposed between them. The parallel light goes through the mirror M3 and enters as such the objective lens Ob, focusing on the focal plane F. In the section of FIG. 2(b) where the refracting power of the cylindrical lens CL1 (CL2) works, on the other hand, a light beam through the cylindrical lens CL1 (CL2) turns under its positive refracting power into convergent light that converges in front of the positive lens L3. In the rear of the point of convergence, that convergent light turns into divergent light that is then incident on the positive lens L3. That divergent light again turns under the positive refracting powers of the positive lenses L3 and L4 into convergent light that converges in front of (on the viewing side) the objective lens Ob. In the rear of the point of convergence, the light, divergent this time, enters the objective lens Ob, and focuses at a minute distance Δ off the focal plane F under the positive refracting power of the objective lens Ob. For this reason, the laser light is incident on the focal plane (subject surface) F: it is incident on a point in the section where the refracting power of the cylindrical lens CL1 does not work while it is incident on a certain width in the section where the refracting power of the cylindrical lens CL1 works, so that it can focus on the focal plane (subject surface) F in a linear or elliptic form. In other words, the laser light focuses on the focal plane (subject surface) F in two linear areas extending in the direction orthogonal to the generator of the cylindrical lens CL1, CL2. And then, the position of each linear light-collective area is arbitrarily adjustable within the focal plane (subject surface) F by the adjustment of the position and angle of the mirror M1, M2 in the optical path, respectively. Further, the direction of that area is adjustable by the adjustment of the angle of each cylindrical lens CL1, CL2 about the optical axis. In such an arrangement, a shutter was mounted on the s-polarized beam a optical path (running from the first polarizing beam splitter BS1 to the mirror M2 and the second polarizing beam splitter BS2 via the cylindrical lens CL2) while light made its way through only the p-polarized beam path (running from the first polarizing beam splitter BS1 to the mirror M1 and the second polarizing beam splitter BS2 via the cylindrical lens CL1). Then, the photographic camera 4 was used to pick up the behavior of microscopic particles dispersed in a fluid flowing in the flow passage 5 in the case where one linear light-collective area was positioned in the flow passage 5 through the microchannel MC. Consequently, such results as shown in FIG. 3 were obtained. FIG. 3(a) is illustrative in schematic of how microscopie particles 11 dispersed in the fluid behaves in the case where the angle of the cylindrical lens CL1 is adjusted to form a linear light-collective area 10 with its direction lying in the Y-axis direction orthogonal to the direction (X-axis direction) of a flow in the flow passage 5. The laser light oscillated from the laser 1 is Gaussian distribution one with an intensity peak at the center: the linear light-collective area 10 has the highest intensity at the center. Accordingly, the microscopic particles 11 flowing at right angles with the linear light-collective area 10 under the radiation pressure of laser light go in the linear light-collective area 10, and once the microscopic particles 11 enter the linear light-collective area 10, they move from both its sides, gathering together in the central direction. FIG. 3(b) is illustrative, as in FIG. 3(a), of the case where an almost half of the Gaussian distribution beam focusing on the focal plane F is blocked off halfway down in the optical path to bring the position of the linear light-collective area 10 having the highest intensity to near the right end of the drawing. In this case, the microscopic particles 11 flowing at right angles with the linear light-collective area 10 under the radiation pressure of laser light go into the linear light-collective area 10, and once the microscopic particles 11 enter the linear light-collective area 10, they move from the left to the right end of the drawing. The microscopic particles 11 gathering near that right end are saturated, leaving that right end in the flowing direction. FIG. 3(c) is a schematic view illustrative of how microscopic particles 11 dispersed in the fluid behaves in the case where the angle of the cylindrical lens CL1 is adjusted to form a linear light-collective area 10 with its direction lying obliquely at an angle with the direction of a flow in the flow passage 5 (the X-axis direction). In this case, the microscopic particles 11 flowing at an angle with the linear light-collective area 10 under the radiation pressure of laser light go into the linear light-collective area 10, and once the microscopic particles 11 enter the linear light-collective area 10, they move a direction along the flow, or from the upper left to the lower right of the drawing when the linear light-collective area 10 tilts as shown. Then, the microscopic particles gathering together at that lower right end are saturated, leaving the lower right end in the direction of the flow. Reference is then made to a modification to the inventive arrangement of FIG. 1 wherein light of almost equal intensity goes along both the p- and s-polarized beam paths: an account is given of how microscopic particles 11 dispersed in a fluid flowing in the flow passage 5 behaves where two linear light-collective areas 101 and 102 are located in the flow passage 5 through microchannel MC. As shown in FIG. 4(a), the angles of cylindrical lenses CL1 and CL2 are adjusted with their refracting powers acting in the same direction to form two light-collective areas 101 and 102 at the same position in the direction of a flow within the flow passage 5 and with their directions lying orthogonal to that direction; as shown in FIG. 3(b), the left linear light-collective area 101 is positioned such that there is the highest intensity at the right end, and the right linear light-collective area 102 is positioned such that there is the highest intensity at the left end; and between the left 101 and the right linear light-collective area 102, there is a gap formed by the adjustment of the position and angle of the mirror M1 at the p-polarized light beam path and by the adjustment of the position and angle of the mirror M2 at the s-polarized light beam path. Then, the microscopic particles 11 flowing at right angles with the linear light-collective areas 101 and 102 under the radiation pressure of laser light go into the respective linear light-collective areas 101 and 102, and once they enter the linear light-collective areas 101 and 102, they move from the left to the right end of the area 101 and from the right to the left end of the area 102: they pass through the gap between the left 101 and the right linear light-collective area 102 as if focused or concentrated on that gap. As shown in FIG. 4(b), the angles of cylindrical lenses CL1 and CL2 are separately adjusted such that at the same position in a direction of a flow within the flow passage 5, the left linear light-collective area 101 lies in an obliquely lower right direction and the right linear light-collective area 102 lies in an obliquely lower left direction, as shown in FIG. 3(c), and between the lower right end of the left 101 and the lower left end of the right linear light-collective area 102, there is a gap formed by the adjustment of the position and angle of mirrors M1 and M2 in the respective optical paths. Then, microscopic particles 11 flowing at angles with the linear light-collective areas 101 and 102 under the radiation pressure of laser light go into the respective linear light-collective areas 101 and 102, and once they enter the linear light-collective areas 101 and 102, they move from obliquely above to below in the drawing: they pass through the gap between the left 101 and the right linear light-collective area 102 as if focused or concentrated on that gap. As shown in FIG. 4(c), the angles of cylindrical lenses CL1 and CL2 are adjusted with their refracting powers acting in the same direction such that the left and right light-collective areas 101 and 102 at the same position in the direction of a flow within a flow passage 5 are formed parallel at a spacing in an obliquely lower right direction. Then, microscopic particles 11 flowing at angles with the linear light-collective areas 101 and 102 under the radiation pressure of laser light go into the linear light-collective areas 101 and 102, and once they enter the linear light-collective areas 101 and 102, they move from obliquely above to below of the drawing. The microscopic particles 11 gathering together at the lower ends of the respective linear light-collective areas 101 and 102 are saturated, leaving the respective lower ends while separated into two. As shown in FIG. 4(d), the angles of cylindrical lenses CL1 and CL2 are separately adjusted such that at the same position in the direction of a flow within a flow passage 5, the left linear light-collective area 101 lies in an obliquely lower left direction and the right linear light-collective area 102 lies in an obliquely lower right direction, as shown in FIG. 3(c), and the areas 101 and 102 are positioned by the adjustment of the positions and angles of mirrors M1 and M2 in the respective optical paths with the upper right end of the left 101 in contact with the upper left end of the right linear light-collective area 102. Then, microscopic particles 11 flowing at angles with the linear light-collective areas 101 and 102 under the radiation pressure of light laser go into the respective linear light-collective areas 101 and 102, and once they enter the linear light-collective areas 101 and 102, they move from obliquely above to below of the drawing, whereupon the microscopic particles 11 gathering together at the lower ends of the linear light-collective areas 101 and 102 are saturated, leaving the respective lower ends while separated into two. As described above, by the adjustment of the angles and relative positions of two linear light-collective areas 101 and 102 formed within the flow passage 5 with respect to the direction of the flow, for instance, it is possible to pick up, collect, concentrate, separate, deflect, deliver, mix, and sort out suspending microscopic particles, cells, DNAs or the like flowing within the flow passage 5. Fast rotation of the cylindrical lenses CL1 and CL2 is capable of stirring, mixing or otherwise processing them, too. Of course, the provision of three or more linear light-collective areas 10 formed by simultaneous collection of light makes more complicated manipulations possible. In the arrangement of the embodiment of FIG. 1, cylindrical mirrors may just as well be used in place of the cylindrical lenses CL1 and CL2; instead of the mirrors M1 and M2, other optical elements such as prisms may just as well be employed; and in lieu of the beam splitters BS1 and BS2, other light splitting means or optical combinations such as half-silvered mirrors may just as well be used. While the optical substance manipulator of the invention has been described with reference to some embodiments, it is contemplated that the invention is in no sense limited to them, and so many modifications could be possible. For instance, it is understood that the number of linear light-collective areas to be formed within the flow passage is not always limited to two; three or more such areas may just as well be used.
045445206	summary	FIELD OF THE INVENTION The invention relates to laser targets and more particularly laser targets comprising microspheres surrounded by at least one shell. BACKGROUND OF THE INVENTION Laser neutron production depends on the use of intense, short pulse width laser radiation to produce thermonuclear reaction or "burn" in an appropriate fuel. The laser radiation causes the fuel to literally implode upon itself, thereby producing a density in temperature at which the burn can effectively occur. Ideally, the most efficient burn should be created by a perfectly spherical symmetric implosion of the fuel. This requires the fuel to be present in a spherical form and to be irradiated simultaneously and uniformly about its entire outer periphery or the outer periphery of its spherical container. One type of target structure and method of its preparation is taught in U.S. Pat. No. 4,038,125 to Fries et al. The Fries et al. patent teaches a laser target constructed on a thin plastic film on the order of 500 .ANG. in width. Although this type of target structure is highly suitable for use, there are times when plastic is not desirable inside the shell. Furthermore, such a target is not glued together but is fabricated utilizing a thermosetting plastic. The most common type of laser target structure at present comprises a microballoon and at least one surrounding shell affixed to a single stalk. This structure requires micromanipulation within three dimensions to position and hold the shells while the glue sets. Fabrication of a single target is difficult and time consuming requiring two microscopes for assembly. The diameter of the stalk is on the order of 5 to 10.mu.. In fabricating a target on a stalk, a first plastic spherical shell is cut into hemispheres and a 10 .mu.m hole is drilled near the pole of one of the hemispheres. A stalk is selected and its 5 .mu.m tip is ground flat perpendicular to its longitudinal axis. The 5 .mu.m flat tip of the stalk is inserted through the 10 .mu.m hole in the drilled hemisphere and is positioned 50 .mu.m away from and pointed at the center point of the hemisphere. The drilled hemisphere is then glued to the stalk and a microballoon is glued to the tip of the stalk so that it is positioned at what will be the center of the sphere formed when the undrilled hemisphere is glued to the drilled hemisphere to form a sphere about the microballoon. The edges of the undrilled hemisphere are then aligned with the edges of the drilled hemisphere and glued thereto. The target structure which is the subject of the instant invention is useful in producing neutrons. Several references which illustrate the use of and describe such targets are "More Evidence That Fusion Works" by Harlow G. Ahlstrom and John F. Holzrichter, Laser Focus, Sept. 1975, Vol. 11, No. 9, page 39 et seq., "Laser-Driven Compression of Glass Microspheres," P. M. Campbell et al., Physical Review Letters, Vol. 34, No. 2, Jan. 13, 1975, pages 74-77, "Double-Shell Target Designs for the Los Alamos Scientific Laboratory Eight-Beam Laser System," Joseph M. Kindel and Michael A. Stroscio, LA-7167-MS, March 1978, "Spatially Resolved .alpha. Emission from Laser Fusion Targets," N. M. Ceglio and L. W. Coleman, Physical Review Letters, Vol. 39, No. 1, July 4, 1977, "Implosion Experiments With D.sub.2, .sup.3 He Filled Microspheres," V. W. Slivinsky et al., Preprint UCRL-78450 Rev. 1, Mar. 11, 1977, and "Laser-Fusion Ion Temperatures Determined by Neutron Time-Of-Flight Techniques," R. A. Lerche et al., Preprint UCRL-79375, April 1977. One object of the present invention is to simplify the assembly of laser target structures. Another object of the present invention is to provide for relatively easy accurate assembly of multi-shell targets. One advantage of the present invention is that the shells surrounding the microsphere need only be manipulated in two dimensions in order to center the microsphere within the shell during target fabrication. Another advantage of the instant invention is that the target constructed in accordance therewith is relatively free of undesirable constituents within the shell assembly. SUMMARY OF THE INVENTION In accordance with the present invention, there is provided a method of assembling a laser target structure comprising the steps of fixing at least two glass fibers essentially at right angles to one another across an orifice in a plate, gluing to each of the fibers a microsphere essentially at its equator so that it is disposed in one quadrant formed by the crossed fibers and affixed to each, and forming at least one shell about said microsphere in fixed position thereabout by gluing hemispheres of equal size to the crossed fibers to enclose the microsphere essentially at the center of a spherical shell formed by mating the two hemispheres.
	description	This Application claims the benefit of U.S. Patent Application No. 61/070,880, filed Mar. 26, 2008, which is hereby incorporated by reference in its entirety. Aerosol neutralizers are utilized in a variety of aerosol application and test devices, including characterization of aerosols that are sparsely populated (e.g. the monitoring of clean room environments) as well as aerosols that are particle laden (e.g. combustion engine exhaust, coating sprays). The primary task of the aerosol neutralizer is to condition the aerosol to obtain a reproducible, steady-state population of particles having a distribution of charged (positive and negative) particles and neutral particles that is known to within an acceptable uncertainty, and to produce such a characteristic in the aerosol regardless of the charge condition of the aerosol entering the aerosol neutralizer. By conditioning the aerosol to a known steady-state population, the total concentration of particles can be inferred by measuring only a portion of the particle distribution (e.g., particles of a certain size, mobility, and/or charge). For example, some detectors detect only positively charged particles within a given size range. Because the steady state population of particles is reasonably known relative to the positively charged particles within the size range, the total concentration of the particles can be inferred. An unconditioned aerosol stream may not possess the steady state characteristics, thus rendering the inference meaningless. One way to condition an aerosol is to bombard it with x-rays. The x-rays interact with the gas in the aerosol, producing a bi-polar population of ions. These ions then interact with the particles of the aerosol, thereby transferring charge to the particles. Particles having a high charge upon entering the aerosol neutralizer will attract oppositely charge ions generated in the gas, thus tending to neutralize the particle. By this same mechanism, most of the smaller particles will not sustain multiple charges of a given polarity. Larger particles can sustain multiple charges by virtue of their size. See Wiedensohler, “An Approximation of the Bipolar Charge Distribution for Particles in the Submicron Size Range,” J. Aerosol Sci., vol. 19, no. 3, pp. 387-389, 1988. Accordingly, the steady state distribution of the aerosol population comprising a mixture of neutral particles, single-charged particles and multiple-charged particles is rapidly attained under x-ray bombardment. Conventional neutralizing devices utilizing radioactive substances such as americium (241Am), krypton (85Kr), polonium (210Po) and the like are known to produce a bipolar population of charged particles in an aerosol. Such devices carry with them concerns stemming from the hazardous radiation attendant the radioactive substance and from the gradual decrease of effectiveness characterized by the half-life. Americum has a half-life of 432 years and krypton a half-life of 11 years, thus posing safety concerns both in terms of personnel utilizing and storing the device, and in terms of disposal of the unit when its operational life is at an end. Polonium has a substantially shorter half life (138 days), which may mitigate against long term disposal concerns, but presents additional handling concerns as the radioactive substance typically requires replacement during the operational life of the neutralizer. Recently, U.S. Patent Application Publication No. 2006/0108537 disclosed an aerosol particle charging device that utilizes “soft” x-rays, that is, x-rays having a wavelength in the range of approximately 0.13- to 2-nm and having photon energies in the range of approximately 600- to 10,000-electron-volts (eV). Soft x-ray devices eliminate concerns regarding handling of radioactive materials because the soft x-ray emitter does not utilize or produce radioactive materials nor does it emit any radiation when no power is supplied to it. However, both the conventional and the soft x-ray devices are known to generate particles by a process of radiolytic precipitation. Radiolytic precipitation is the result of a cascade of events beginning with ionization of individual molecules which form reactive species from gas constituents and impurities in an aerosol, subsequently interacting with each other to condense into particles. Hence, aerosol neutralizers utilizing x-ray devices typically add particles to an aerosol stream via radiolytically produced particle. The generated particles are generally undesirable, as they typically add particles of unknown size and composition to an aerosol, thereby distorting the aerosol that is being characterized. A neutralizer that provides the radioactivity-free operation of the soft x-ray emitter without significant radiolytic generation of particles would be welcome. Various embodiments of the invention reduce the radiolytic generation of particles to a negligible amount while still fully conditioning an aerosol stream, even at high flow rates. The reduction in the radiolytic generation of particles is accomplished by reducing by several factors the intensity of the soft x-rays that bombard the aerosol flow being conditioned. We have found that the reduction in radiolytically generated particles drops exponentially in relation to the decrease in the intensity of the soft x-rays, while the reduction in the production of the bi-polar population in ions is only modestly reduced. The result is that the radiolytic generation of particles is disproportionately diminished relative to the reduction in the generation the of bi-polar population of ions. Furthermore, we have discovered that in some instances the intensity of a standard soft x-ray emitter can be reduced by as much as a factor of 33 times and still produce a bi-polar population of ions sufficient to neutralize an aerosol. Structurally, a soft x-ray emitter is configured to irradiate an aerosol conditioning chamber through which an aerosol passes. An attenuating window may be positioned between the soft x-ray emitter and the interior passage of the aerosol conditioning chamber so that the soft x-rays passing therebetween pass through the attenuating window. Through proper selection of material and thickness, the intensity of the soft x-rays that irradiate the aerosol flow can strike a balance whereby the radiolytic generation of particles is insignificant for a given application while the conditioning of the aerosol flow is still complete. In one embodiment, an aerosol conditioning device comprises an aerosol conditioning chamber having an inlet and an outlet and defining an interior flow passage. A soft x-ray emitter is operatively coupled with the aerosol conditioning chamber, with an attenuating window disposed between the soft x-ray emitter and the interior flow passage. The attenuating window may be adapted to reduce the intensity of soft x-rays emitted by the soft x-ray emitter so that radiolytically generated particles produced by the soft x-rays within the interior flow passage is insignificant. The attenuating window may be configured to reduce the intensity of soft x-rays emitted by the soft x-ray emitter by a factor of approximately 33. The soft x-rays entering the aerosol conditioning chamber may be tailored to produce an x-ray intensity of approximately 0.045 Sievert/hour or less, depending on the sensitivity of the downstream measurements to radiolytically generated particles. In another embodiment, a method for neutralizing an aerosol while generating an insignificant amount of radiolytically generated particles comprises providing a soft x-ray emitter operatively coupled with an aerosol conditioning chamber defining an interior flow passage, the soft x-ray emitter being configured to produce soft x-rays of a rated intensity. The x-ray emitter is then caused to emit soft x-rays. The intensity of the soft x-rays produced by the soft x-ray emitter is reduced to provide soft x-rays of a reduced intensity relative to the rated intensity. At least a portion of the reduced intensity soft x-rays is caused to enter the aerosol conditioning chamber and to pass through the conditioning chamber. The aerosol is thereby bombarded with the soft x-rays of reduced intensity as the aerosol passes through the conditioning chamber to generate an insignificant number of radiolytically generated particles. Referring to FIG. 1, a dual ordinate graph 20 having a radiolytically generated particle ordinate 22 and a bi-polar population of ions ordinate 24 vs. an x-ray intensity abscissa 26 is presented. A radiolytic production characteristic 28 and a bi-polar population characteristic 30 as generated by soft x-rays are depicted on the dual ordinate graph 20. The radiolytic production characteristic 28 is generally proportional to the x-ray intensity abscissa 26 raised to a power M, i.e.RGP∝XM Eqn. (1)where RGP is the radiolytically generated production rate, X is the x-ray intensity, and M is a value greater than unity and believed to be typically greater than 2. The bi-polar population characteristic 30 may range from approximately a square root function to approximately a linear function with respect to the x-ray intensity abscissa 26:BPP∝XN Eqn. (2)where BPP is the bi-polar population at x-ray intensity X and N is in the range of approximately ½ to 1. A full power x-ray intensity level 34 for a typical soft x-ray emitter is depicted on the x-ray intensity abscissa 26, at which level the radiolytic production characteristic 28 is at a first value RGP1 and the bi-polar population characteristic 30 is at a first value BPP1. Typically, BPP1 is substantially greater than is required to adequately condition an aerosol flow through a neutralizer. Moreover, because the power M of the radiolytic production characteristic 28 typically greater than two and the bi-polar population characteristic 30 is approximately linear or sub-linear, the value of the RGP will decrease in greater proportion than will the value of the BPP as the x-ray intensity X is decreased. Accordingly, an adequate x-ray intensity level 36 may be established that is less than the full power x-ray intensity level 34, where the bi-polar population characteristic 30 is at a second value BPP2. A corresponding value RGP2 of the radiolytic production characteristic 28 is also established at the adequate x-ray intensity level 36. The dual ordinate graph 20 illustrates that the proportionate change between RGP1 and RGP2 is substantially greater than the proportionate change between BPP1 and BPP2. Therefore, while the bi-polar population of ions 24 remains adequate, the radiolytically generated particle production may become insignificant or marginal in terms of the contribution of particles to the aerosol being conditioned. Referring to FIG. 2, a soft x-ray neutralizer (SXRN) 40 is depicted in an embodiment of the invention. The soft x-ray neutralizer 40 includes a soft x-ray emitter 42 operatively coupled with an aerosol conditioning chamber 44 that defines an interior flow passage 45. An unconditioned aerosol 46 may be introduced into the interior flow passage 45 through a first port 48. Soft x-rays 50 are emitted from the soft x-ray emitter 42 and directed into the interior flow passage 45 of the aerosol conditioning chamber 44. A conditioned aerosol 54 emerges from the aerosol conditioning chamber 44 via a second port 56. An obstruction 58 such as a sphere or perforated plate may be placed upstream of the second port 56. An attenuating window 60 may be placed between the soft x-ray emitter 42 and the interior of the aerosol conditioning chamber 44. Alternatively, the flow of aerosol may be reversed. That is, the unconditioned aerosol 46 may enter the second port 56 and the conditioned aerosol 54 exit via port 48. Because the bi-polar population of ions tends to be more concentrated near the soft x-ray emitter, the reversed flow configuration may change the residence time of the bi-polar population of ions within the aerosol conditioning chamber 44. The change in residence time of the ions can be a factor in the radiolytic generation of particles. In operation, the unconditioned aerosol 46 may be bombarded with soft x-rays 50 emitted from the soft x-ray emitter 42 as the aerosol passes through the aerosol conditioning chamber 44. The soft x-rays 50 interact with the carrier gas of the aerosol to generate ions, which in turn can interact with the particles in the aerosol to transfer charges to the particles. The attenuating window 60 may form a fluid flow barrier between the internal components of the soft x-ray emitter 42 and the aerosol conditioning chamber 44. The obstruction 58 blocks the direct line-of-sight between the attenuating window 60 and the second port 56 for enhanced safety of personnel in the area. Alternatively, the blocking function may also be accomplished by imposing a bend or turn or serpentine in the structure that defines the second port 56. The attenuating window 60 may be comprised of a material and thickness that substantially reduces the intensity of the soft x-rays 50 that enter the aerosol conditioning chamber 44. The attenuation may be tailored so that the intensity of the soft x-rays 50 is adequate to condition the unconditioned aerosol 46 as it flows through the aerosol conditioning chamber 44, as described in the discussion of FIG. 1. The reduced intensity of the soft x-rays 50 also provides the attendant and disproportionately larger reduction in the production of radiolytically generated particles. Experiments were devised and executed to determine the feasibility of the foregoing method and apparatus. The experiments and results are described below. Referring to FIG. 3, a particle generation test setup 70 was devised to test whether the soft x-ray neutralizer 40, either attenuated or unattentuated, produced radiolytically generated particles. For the tests under discussion, the “unattenuated” configuration of the soft x-ray neutralizer comprised a window of mylar of 0.004-in. thickness. In the “attenuated” configuration, the window 60 further included multiple layers of aluminum foil totaling 0.005-in. thickness. (The attenuation provided is a function of the total thickness of material, not the number of layers.) The attenuated configuration was found to reduce the intensity of the soft x-rays entering the aerosol neutralizing chamber 44 by a factor of approximately thirty-three (i.e. from approximately 1.5 Sievert/hour to approximately 0.045 Sievert/hour). The intensity of the soft x-rays entering the neutralizing chamber 44 was estimated by interpolating the specifications of the soft x-ray emitter 42. The soft x-ray emitter 42 used in the particle generation test setup 70 was a Hamamatsu L9490, which specifies an x-ray dose at a distance of one meter from the output window of the device of 0.015 Sievert/hour. The midpoint of the neutralizing chamber 44 was approximately 10-cm from the output window. Because radiation intensity varies by the inverse of the distance squared, the dose at 10-cm will be approximately 100 times greater than at 1-m, putting the dose at about 15 Sievert/hour without attenuation. For an attenuation factor of 33, the attenuated x-ray intensity for the particle generation test setup 70 was therefore approximately 0.045 Sievert/hour. The SI unit of radiation dose is the Gray, which is the amount of radiation that deposits 1 Joule in a kilogram of absorbing material. The Sievert is the Gray dosage multiplied by a factor that includes damage to biological tissue. For example, penetrating ionizing radiation (e.g., gamma and beta radiation) have a factor of about 1, so 1 Sievert=approximately 1 Gray. Alpha rays have a factor of 20, so 1 Gray of alpha radiation dosage=20 Sievert. The soft x-ray neutralizer 40 was configured so that an unconditioned atmospheric flow stream 72 was drawn through a pair of high efficiency particulate air (HEPA) filters 74 connected in series in order to remove substantially all particles from the flow stream and produce a clean air flow 75 that enters the soft x-ray neutralizer 40. An exit flow 76 from the soft x-ray neutralizer 40 was directed into a condensation particle counter 78 (TSI model 3025) and processing software 79 (TSI Aerosol Instrument Manager Software for CPC). The soft x-ray neutralizer 40 was operatively coupled to an on/off control 80. It is further noted that the soft x-ray neutralizer 40 was configured for reverse flow in the particle generation test setup 70 (aerosol entering port 56 and exiting first port 48). In operation, the soft x-ray neutralizer 40 could either be in an inactive state (i.e. controller 80 off) or an active state (i.e. controller 80 on). With the soft x-ray neutralizer 40 in the inactive state, the condensation particle counter 78 measures only the particles that pass thorough the pair of HEPA filters 74. With the soft x-ray neutralizer in the active state, the particles detected by the condensation particle counter 78 would be the combination of what passed through the HEPA filters 74 and the particles radiolytically generated by the soft x-ray neutralizer 40 in operation. Because of the extensive filtration, it was expected that the amount of particles detected by the condensation particle counter 78 would be very low with the soft x-ray neutralizer 40 in the inactive state, and that the particles detected by the condensation particle counter 78 would comprise substantially only the particles produced radiolytically by the soft x-ray neutralizer 40 in the active state. Referring to FIGS. 4 through 6, the results of the particle generation test are presented. A high flow rate result 90 is presented in FIG. 4, wherein the particle generation test setup 70 was adjusted to draw 1.5 liters per minute (LPM) of air therethrough. During this test, the soft x-ray neutralizer was active and in an unattenuated configuration (that is, with the mylar window of 0.004-in. thickness between the x-ray emitter 42 and the aerosol conditioning chamber 44). The graph of FIG. 4 plots an elapsed time 92 of the experiment vs. the overall particle concentration 94 indicated by the condensation particle counter 78 on a logarithmic axis. An interval of inactivity 96 is also presented in FIG. 4, wherein the soft x-ray neutralizer 40 was in an inactive state. The high flow rate results 90 indicate overall particle concentrations detectable by the condensation particle counter to be largely in the range of 0.01- to 1.0-particles per cubic centimeters (#/cc). No detectable particles were found during the interval of inactivity 96, implying that the particles detected during the high flow rate experiment are purely radiolytically generated particles. Generally, a radiolytically generated particle contribution of 1.0#/cc or less is considered satisfactory in many applications. A low flow rate result 100 is presented in FIG. 5, wherein the particle generation test setup 70 was adjusted to draw 0.3 liters per minute (LPM) of air therethrough. As with the high flow rate result 90, the low flow rate result 100 was generated using an unattenuated soft x-ray neutralizer 40, and is characterized by a period of inactivity. The low flow rate results 100 indicate overall particle concentrations detectable by the condensation particle counter to be initially in the range of 200 to 2000#/cc, and dropping to approximately 10#/cc after the period of inactivity 96. The detectable level of particles found during the interval of inactivity 96 was on the order of 0.1#/cc, which is two to four orders of magnitude less than the concentration measurements acquired in the active state; hence, the contribution of non-radiolytic particles can be presumed negligible. The substantially higher particle concentrations for the low flow rate results 100 may be problematic in many applications. Second low flow rate results 110 and 120 are presented in FIGS. 6 and 6A, wherein the soft x-ray neutralizer 40 was arranged for the attenuated configuration. The low flow rate of 0.3 LPM was chosen because of the potentially problematic result demonstrated with the low flow rate result 100. The initial second low flow rate result 110 presents data that was acquired over a period of approximately 2 hours. Initially, the production of radiolytically generated particles was approximately 2#/cc, rapidly decreasing to approximately 0.1#/cc, then steadily decreasing into approximately 0.01#/cc. Accordingly, the second low flow rate results 110 may be characterized as demonstrating that the attenuated configuration produces radiolytically generated particle concentrations that are typically less than 1#/cc, which constitutes a decrease in the production of radiolytically generated particles of over three orders of magnitude in some instances over the non-attenuated counterpart of the low flow rate results 100. After the initial second flow rate result, additional results 120 were obtained for approximately one more hour. During this time, no detectable levels of radiolytically generated particles were detected. At approximately the 3400-second mark of this test, the two HEPA filters 74 were removed from the system, which caused an increase 122 in the detected particles. Because the particle production decayed to an undetectable level, it is believed that the particles detected for the second flow rate result 110 were the result of the attenuated soft x-rays reacting with residue and/or contaminants left behind on the exposed surfaces of the aerosol conditioning chamber 44 during previous experiments. After the aerosol conditioning chamber 44 was effectively cleansed of these effects, the attenuated soft x-rays no longer generated a detectable level of particles. Accordingly, the detected particles of the second flow rate result 110 are not believed to have been the result of an interaction between the attenuated soft x-rays and the clean air flow 75. Furthermore, it is noted that the particle increase at the end of the second flow rate result 120 is believed to have nothing to do with radiolytically generated particles. Rather, these are particles that entered the condensation particle counter 78 from ambient by virtue of the attenuated soft x-ray neutralizer 40 being unfiltered. The purpose of the removal of the filters 74 was to verify that the condensation particle counter 78 was still operating. Accordingly, the attenuated configuration reduced the production of radiolytically generated particles associated with the low flow rate condition to an acceptable or insignificant level, whereas the concentration of radiolytically generated particles produced by the unattenuated configuration at the low flow rate was significant and generally unacceptable. The descriptors “high flow rate” and “low flow rate” describes only the flow rates as they relate to each other, and are not intended to indicate or imply a limitation of the invention. Also, the level of radiolytically generated particles deemed “insignificant” or “acceptable” depends on the application. For example, in a Class 1 clean room environment used in semiconductor manufacture, the production of radiolytically generated particles may need to be less than 10−4 particles/cc, whereas in the monitoring of urban atmospheric aerosols a production of radiolytically generated particles of 1 particles/cc may be satisfactory. Having demonstrated that the attenuated configuration substantially reduces the production of radiolytically generated particles over the unattenuated configuration, a remaining question is whether the attenuated SXRN is effective for the task of conditioning the aerosol. A test was devised and executed to determine the effectiveness of the attenuated configuration, described below. Referring to FIG. 7, a conditioning test setup 170 is depicted to test the attenuated configuration of the soft x-ray neutralizer 40 of the invention. The conditioning test setup 170 included a salt aerosol generator 172, a diluter 174, a particle charger 176, the soft x-ray neutralizer 40 in the attenuated configuration, and a scanning mobility particle sizer 177 comprising a differential mobility analyzer (DMA) 178 and the condensation particle counter 78, all in serial fluid communication with each other as depicted in FIG. 7. A vent 180 was located between the particle charger 176 and the soft x-ray neutralizer 40. Also, a flow controller 182 was operatively coupled between the soft x-ray neutralizer 40 and the scanning mobility particle sizer 177. The diluter 174 included a first flow path 184 and a second flow path 186, the flow paths 184 and 186 being in parallel with each other, the second flow path 186 including a high efficiency particulate air (HEPA) filter 192. The diluter 174 further included a pair of valves 194, one for each of the flow paths 184 and 186. The particle charger 176 was a unipolar corona-jet charger obtained from a TSI Model 3070A electrical aerosol detector, and included an on/off control 196. The particle charger 176 was set up to accept a regulated clean air flow 198 for the corona air flow. The clean air flow 198 was passed through the particle charger 176 at a rate of approximately 0.4 LPM for this work. In operation, the salt aerosol generator 172 produced 3.5 liter/minute of aerosol 200 that passed through the diluter 174 and comprising particles of salt. The valves 194 on the diluter could be adjusted to route more or less aerosol through the HEPA filter 192, thus reducing or increasing, respectively, the concentration of the aerosol 200 being passed on for testing. The net flow through the soft x-ray neutralizer 40 was controlled as the sum of the fixed flow through the scanning mobility particle sizer 177 and the adjustable flow through the flow controller 182. The vent 180 provided a path for escape of excess test aerosol flow from the charger 176. The particle charger 176 could either be in an active state (i.e. controller 196 on) or an inactive state (i.e. controller 196 off). When in the active state, the particle charger 176 imposes a charge on the aerosol 200 as it enters the attenuated soft x-ray neutralizer 40. When in the inactive state, the particle charger 176 is a pass-through device that does not substantially alter the charge distribution of the aerosol 200 as it enters the attenuated soft x-ray neutralizer 40. The purpose of the DMA 178 was to provide a variable filter that passes particles of a given mobility determined by the voltage setting of the DMA 178. In operation this voltage is scanned while the CPC 78 measures the concentration of particles passing through the DMA 178. The result is a mobility distribution measurement (often interpreted as a size distribution measurement). Two tests were conducted with the conditioning test setup 170, both with the flow rate through the attenuated soft x-ray neutralizer 40 being set at 3.0 LPM by drawing 1.5 LPM through the scanning mobility particle sizer 177 and an additional 1.5 LPM through the flow controller 182. The higher flow rate was chosen because the shortened residence time in the aerosol conditioning chamber 44 subjects the aerosol to less bombardment of soft x-rays, thus posing a greater challenge to produce a conditioned exit flow. The first test was conducted with the particle charger 176 in an active state. The second test was conducted with the particle charger 176 in an inactive state. Accordingly, the aerosol entering the attenuated soft x-ray analyzer 40 would be highly charged when the particle charger 176 was activated, and would be representative of an ambient or natural charge when the particle charger 176 was in an inactive state. Referring to FIG. 8, a particle distribution 220 is presented including the results from the active state test 222 and the results from the inactive state test 224. The particle distribution 220 presents a normalized number concentration of an aerosol 226 (dN/dlogDp, in units of counts/cc per log diameter range) vs. the mobility diameter 228 of the particles within the aerosol. The dN/dlogDp parameter (hereinafter “normalized number concentration”) comprises the number of particles or droplets contained within a mobility diameter interval normalized against the size or “bin width” of the interval. The normalization enables comparison of distributions having different bin widths. To count the total number of particles within a size range, one adds the normalized number concentrations within the size range and multiplies it by the dlogDp (bin width). Here, “dlogDp” or “bin width” is defined as the difference between the base-10 logarithm of the upper limit of the interval and the base-10 logarithm of the lower limit of the interval (i.e. the “bin width” is the base-10 logarithm of the ratio of the upper limit to the lower limit of the interval). The software 79 of the scanning mobility particle sizer 177 is programmed with certain assumptions in inferring the concentration of particles within a given bin width from a measured particle count. The assumptions include a Fuchs charge distribution for the particles. When the particle charger 176 is in the active state, the actual charge distribution of the particles entering the attenuated soft x-ray neutralizer 40 violates this assumption. Therefore, if the attenuated soft x-ray neutralizer 40 is not conditioning the charged aerosol sufficiently to attain the Fuchs condition, a substantial difference between the two tests 222 and 224 would be observed. Instead, the results from the two tests 222 and 224 are in close agreement with each other. Such a result implies that the attenuated soft x-ray neutralizer 40 is adequately conditioning the aerosol, regardless of its charged state upon entering the neutralizer 40. Another way to reduce the intensity of the x-rays entering the aerosol conditioning chamber 44 is to manipulate the operating conditions of the x-ray tube. The x-ray energy or wavelength spectrum is determined by the cathode-to-target voltage, together with the material of the target. The x-ray intensity is established by the current of electrons bombarding the target. The current of electrons is determined by the cathode emission which may be controlled either by changing the cathode temperature (e.g. changing the voltage applied to the cathode or the cathode heater), or through the use of additional control electrodes or grids within the tube. Such control of the cathode emission may provide an alternative or additional way to reduce the intensity of the x-rays from the soft x-ray emitter 42. It is noted that x-ray tubes have a limited lifetime, and one of the failure mechanisms is growth of crystals resulting in failure of the heated filament in the tube. Operation at full filament temperature tends to inhibit or slow the crystallization process. The acceleration voltage must typically be maintained in order to get the required x-ray spectrum, and with the full acceleration voltage applied and the filament at full temperature, operation at full current and power results. Thus, while it is possible to reduce the x-ray intensity by reducing the filament temperature, this approach is generally not favored because it reduces tube life. The use of control electrodes may be preferable to reducing filament temperature, but it may not be possible without redesign of the x-ray tube itself. Each of the additional figures and methods disclosed herein may be used separately, or in conjunction with other features and methods, to provide improved devices, systems and methods for making and using the same. Therefore, combinations of features and methods disclosed herein may not be necessary to practice the invention in its broadest sense and are instead disclosed merely to particularly describe representative embodiments of the invention. For purposes of interpreting the claims for the present invention, it is expressly intended that the provisions of Section 112, sixth paragraph of 35 U.S.C. are not to be invoked unless the specific terms “means for” or “step for” are recited in the subject claim.
	abstract	An X-ray examination apparatus changes a position of each X-ray sensor by rotating a sensor base, and resets a starting position of X-ray emission that becomes a X-ray focal position so that the X-ray enters each X-ray sensor after the position thereof is changed. A scanning X-ray source deflects an electron beam to easily change the position where the electron beam impinges a target of the X-ray source to an arbitrary location. The irradiating position of the electron beam then can be easily moved according to an accumulated irradiation time on the target. Therefore, maintenance can be performed without interrupting the X-ray examination.
043483526	description	In a tank 1 made of reinforced concrete, lined with stainless steel plate 2 and filled with water 3, there is a rack 4 which consists of several adjacent rows of rack units 5, of which only one row is visible in the drawing. Each rack unit consists of a solid bottom plate 10, with bores 11 in square division. Between the bores 11, on the underside of the bottom plate 10, mutually parallel ribs 12 are welded on, which are connected together in pairs by straps 13 (See FIG. 4). In the straps 13, threaded bores are provided, in which threaded bolts 14 with hexagonal head 15 are fitted. On the end face, the head 15 of these bolts 14 is machined slightly concave. Against this concave surface a disk 16 applies, whose upper face is convex. The bolts 14 take support through these disks 16 on the steel plate 2 of the tank bottom serving as a lining. To each of the four corners of the bottom plate is welded the end face of an angle section 20 extending upward. The four angle sections 20 are connected at their upper ends with a square frame 21 of flat iron standing upright, which is welded to the circumference of a square cover plate 25. This square cover plate has square openings 26, (See FIG. 2) aligned with the bores 11 of bottom plate 10, the sides of the openings extending parallel to the sides of the cover plate 25. In the center between adjacent rows of openings 26, on the underside of the cover plate 25, are crossing thick ribs 28, also welded to the cover plate 25. The corners between the angle sections 20 and bottom plate 10 on the one hand, and the angle sections and frame 21, on the other, are connected together by diagonally arranged traverses 30. In the corner points between four square openings 26, cross-shaped stop and guide pieces 31 for the loading device are screwed on the cover plate 25. At the edge of the cover plate 25 of a unit, similar cross-shaped stop pieces 32 are arranged, which span the adjacent cover plate and thus connect the individual units together. Under each of the square openings 26, on bottom plate 10, a vertical square receiving tube 40 is mounted, which, leaving little vertical clearance, extends up to the cover plate 25 (See FIG. 2). At the base, the receiving tubes 40 terminate in an inwardly directed flange 41 (See FIG. 3) which rests on the bottom plate 10 and defines an upwardly flaring conical bore 42 for centering the fuel element bundle and four passage holes for the bolts of screws 43. The screws 43 are fitted in matchingly arranged threaded bores of the bottom plate 10. In the four sidewalls of the square receiving tubes 40, at small distance from flange 41, rectangular cutouts 45 are provided, which serve as inlet openings for the naturally circulating water. The square openings 26 in cover plate 25 are wider than the inside contour of the receiving tubes 40 by the slight lateral clearance existing between the upper end of the receiving tubes 40 and the frame 21 or respectively the ribs 28. For capturing the neutron radiation, the square receiving tubes 40 have boron inserts not shown. When the installation is assembled, the receiving tubes 40 are screwed on the finished bottom plate 10 and only then the cover plate 25 with the frame 21 is welded onto the angle sections 20. Then the rack units 5 are introduced into the tank and adjusted there by turning the screws 14 and connected together by the stop pieces 32. After exact dimensional check, water is filled into the tank. Then charging of the receiving tubes 40 with fuel element bundles can take place, the charging device being braced against the guide pieces 31, 32 and centered. For this purpose the guide pieces 31, 32 may have guide bores or slots. In its simplest form (not shown) the rack consists merely of a bottom plate 10 with the receiving tubes 40 screwed thereon. The structure 20, 21, 30 and the cover plate 25 are eliminated. At the receiving tubes 40, the vertical straps remaining in the region of the cutouts 45 may be reinforced for example by angle sections welded on internally.
	claims	1. A radiographic detector panel support comprising:a body composed of a composite material sufficient to structurally support components of a radiographic detector;radiation absorbing material interspersed within the body; andwherein the radiation absorbing material has a mass sufficient to prevent detection of radiation reflected off a back cover of the radiographic detector by radiation detecting components of the radiographic detector. 2. The support of claim 1 wherein the radiation absorbing material includes one of a layer of lead and a layer of barium sulfate. 3. The support of claim 1 further comprising a layer of thermal insulating material secured to the body. 4. The support of claim 1 wherein the radiation absorbing material includes tungsten. 5. The support of claim 1 wherein the composite material includes graphite. 6. The support of claim 1 wherein the body is a planar body and is configured to separate scintillation components of a radiographic detector from a control board of electronics of the radiographic detector. 7. An x-ray detector system comprising:a scintillator configured to convert radiographic energy to light;a detector array having a plurality of detector elements to detect light from the scintillator;a control board having a plurality of electronic components to control the detector array during data acquisition and data readout; anda panel support disposed between the detector array and the control board, the panel support at least partially formed of radiation absorbing material. 8. The x-ray detector system of claim 7 wherein the panel support includes at least one layer of radiation absorbing material. 9. The x-ray detector system of claim 8 wherein the at least one layer has a surface area equivalent to that of the detector array. 10. The x-ray detector system of claim 8 wherein the radiation absorption material includes one of tungsten, lead, and barium sulfate. 11. The x-ray detector system of claim 7 wherein each detector element includes a light sensitive area and an electronics area supported by a glass substrate, and wherein the electronics area includes an electronic switch connected to a capacitive element and the control board. 12. The x-ray detector system of claim 11 wherein the electronic switch includes a thin-film-transistor designed to bias the capacitive element in an energy storage mode during data acquisition and connect the capacitive element to readout electronics of the control board during a readout mode. 13. The x-ray detector system of claim 11 wherein the panel support is further configured to support the glass substrate such that the glass substrate can withstand a point-load of 300 lbs. without fragmentation. 14. The x-ray detector system of claim 7 wherein the scintillator is comprised of Cesium iodide. 15. The x-ray detector system of claim 7 further comprising a cover housing the scintillator, the detector array, the control board, and the panel support, and the cover having a handle to facilitate portability thereof. 16. A method of manufacturing a flat panel x-ray detector comprising the steps of:providing a bulk of non-x-ray absorbing material designed to support internal components of an x-ray detector and wherein the non-x-ray absorbing material is capable of supporting the internal components when a deflective force is applied to the x-ray detector;incorporating x-ray absorbing material into the bulk; andforming an x-ray detector panel support having non-x-ray and x-ray absorbing materials. 17. The method of claim 16 further comprising the steps of:fashioning a first layer of non-x-ray absorbing material and a second layer of non-x-ray absorbing material from the bulk of non-x-ray absorbing material; andsecuring an x-ray absorbing layer to the first and the second layers of non-x-ray absorbing material. 18. The method of claim 17 further comprising the step of bonding the layers of non-x-ray absorbing material and the layer of x-ray absorbing material to one another to form a composite layered structure. 19. The method of claim 17 further comprising the step of:disposing a glass substrate and detector array on the first layer of non-x-ray absorbing material;disposing a layer of scintillation material adjacent the detector array;arranging the first layer and the second layer of non-x-ray absorbing material, the x-ray absorbing layer, the glass substrate and detector array, the layer of scintillation material, and a control board in a stacked arrangement; anddisposing the stacked arrangement in a housing having a handle. 20. The method of claim 16 wherein the non-x-ray absorbing material includes graphite. 21. The method of claim 16 wherein the x-ray absorbing material includes one of lead, tungsten, and barium sulfate. 22. The method of claim 16 further comprising the steps of adding an x-ray absorbing material in powder form to the bulk of non-x-ray absorbing material, mixing the powder of x-ray absorbing material with the non-x-ray absorbing material, and curing the mixture.
048572616	abstract	System provides a positive verification of the presence of a reactor coolant leak in the reactor vessel head area, identifies its location, and enables its size to be determined. A series of video cameras 28 strategically placed about the shroud 16 on the vessel head 13 provide complete viewing coverage. Variable intensity halogen lamps 46, 47 provide illumination for the area to be inspected. The equipment is specially adapted for use in a highly irradiated environment. The system 25 allows for inspection of the reactor vessel head area without the need for shutting down the plant.
048062774	claims	1. A method of decontaminating solid surfaces which are contaminated by substances including radioactive materials, comprising the steps of immersing an object to be decontaminated in a liquid, maintaining said liquid at its saturation temperature or less, producing bubbles in said liquid by blowing vapor therein, and causing said bubbles to burst on a solid surface which is brought into contact with said liquid and which constitutes said object to be decontaminated so that substances adhered to said solid surface are separated and removed by means of an impulsive force produced when said bubbles burst. 2. A method of decontaminating solid surfaces according to claim 1, wherein said vapor is the vapor of a substance which is the same as said liquid. 3. A method of decontaminating solid surfaces according to claim 1, wherein said solid surface is a copper tube. 4. A method of decontaminating solid surfaces according to claim 1, wherein said solid surface is an inside surface of piping. 5. A method of decontaminating solid surfaces according to claim 1, wherein said solid surface is an inside surface of a bath. 6. A method of decontaminating solid surfaces according to claim 1, wherein said substances are soft and hard clads. 7. A method of decontaminating solid surfaces accoding to claim 1, wherein said hard clads are oxide films. 8. A method of decontaminating solid surfaces according to claim 1, wherein said solid surface remains in an installed condition during decontamination.
	description	If an Application Data Sheet (ADS) has been filed on the filing date of this application, it is incorporated by reference herein. Any applications claimed on the ADS for priority under 35 U.S.C. §§119, 120, 121, or 365(c), and any and all parent, grandparent, great-grandparent, etc. applications of such applications, are also incorporated by reference, including any priority claims made in those applications and any material incorporated by reference, to the extent such subject matter is not inconsistent herewith. The present application is related to and/or claims the benefit of the earliest available effective filing date(s) from the following listed application(s) (the “Priority Applications”), if any, listed below (e.g., claims earliest available priority dates for other than provisional patent applications or claims benefits under 35 USC §119(e) for provisional patent applications, for any and all parent, grandparent, great-grandparent, etc. applications of the Priority Application(s)). In addition, the present application is related to the “Related Applications,” if any, listed below. None If the listings of applications provided above are inconsistent with the listings provided via an ADS, it is the intent of the Applicant to claim priority to each application that appears in the Priority Applications section of the ADS and to each application that appears in the Priority Applications section of this application. All subject matter of the Priority Applications and the Related Applications and of any and all parent, grandparent, great-grandparent, etc. applications of the Priority Applications and the Related Applications, including any priority claims, is incorporated herein by reference to the extent such subject matter is not inconsistent herewith. In an aspect, the present disclosure is directed to, among other things, an intra-oral x-ray imaging system. In an embodiment, the intra-oral x-ray imaging system includes an intra-oral x-ray sensor configured to acquire intra-oral x-ray image information associated with a patient. In an embodiment, the intra-oral x-ray imaging system includes an x-ray beam limiter assembly including a controllable x-ray collimator module. In an embodiment, the controllable x-ray collimator module includes an x-ray beam collimation adjustment mechanism that is responsive to one or more inputs including information associated with a border position of the intra-oral sensor. In an embodiment, the intra-oral x-ray imaging system includes an x-ray beam limiter assembly configured to adjust an x-ray beam field of view. In an embodiment, the intra-oral x-ray imaging system includes an x-ray collimator module operably coupled to the intra-oral x-ray sensor and the x-ray beam limiter assembly. In an embodiment, the x-ray collimator module is configured to adjust an x-ray beam field of view responsive to one or more inputs including information associated with a border position of the intra-oral sensor. In an embodiment, the intra-oral x-ray imaging system includes an x-ray beam limiter assembly having one or more shutters (e.g., spring-loaded shutters, solenoid activated shutters, relay device activated shutters, electro-mechanical shutters, etc.). In an embodiment, during operation, the x-ray collimator module is configured to vary a shutter aperture associated with at least one of the one or more shutters responsive to the one or more inputs. In an embodiment, the intra-oral x-ray imaging system includes an x-ray beam limiter assembly having one or more aperture diaphragms. In an embodiment, during operation, the x-ray collimator module is configured to vary a diaphragm aperture of the one or more aperture diaphragms responsive to one or more inputs including information associated with a border position of the intra-oral sensor. In an aspect, the present disclosure is directed to, among other things, an intra-oral x-ray imaging device. In an embodiment, the intra-oral x-ray imaging device includes circuitry configured to determine a position (e.g., location, spatial placement, locality, spatial location, physical location, physical position, etc.) or an orientation (e.g., angular position, physical orientation, attitude, etc.) of an intra-oral x-ray sensor. In an embodiment, the intra-oral x-ray imaging device includes circuitry configured to adjust an x-ray beam field of view responsive to one or more inputs from the circuitry configured to determine the position or orientation of the intra-oral x-ray sensor. In an embodiment, the intra-oral x-ray imaging device includes circuitry configured to acquire intra-oral x-ray image information associated with a patient. In an embodiment, the intra-oral x-ray imaging device includes circuitry configured to generate one or more parameters associated with a field of view setting. In an aspect, the present disclosure is directed to, among other things, an intra-oral x-ray imaging method. In an embodiment, the intra-oral x-ray imaging method includes automatically determining an intra-oral x-ray sensor border position and an intra-oral x-ray sensor orientation. In an embodiment, the intra-oral x-ray imaging method includes varying an x-ray beam field of view parameter (e.g., a field of view size, a diameter dimension, a field of view position parameter, an x-ray field collimation parameter, etc.) responsive to one or more inputs including information associated with the intra-oral x-ray sensor border position and the intra-oral x-ray sensor orientation. In an embodiment, the intra-oral x-ray imaging method includes acquiring intra-oral x-ray image information associated with a patient. In an embodiment, the intra-oral x-ray imaging method includes generating at least one parameter associated with an x-ray imaging mode (e.g., adult panoramic mode, child panoramic mode, high-dose-rate mode, low-dose-rate mode, moderate-dose-rate mode, mandible mode, occlusion mode, maxillary mode, panoramic mode, pulsed fluoroscopy mode, temporomandibular joint mode, etc.) responsive to automatically determining the intra-oral x-ray sensor border position and the intra-oral x-ray sensor orientation. In an embodiment, the intra-oral x-ray imaging method includes varying an x-ray beam aim parameter responsive to automatically determining the intra-oral x-ray sensor border position and the intra-oral x-ray sensor orientation. In an aspect, the present disclosure is directed to, among other things, an intra-oral x-ray sensor. In an embodiment, the intra-oral x-ray sensor includes an x-ray image component configured to acquire intra-oral x-ray image information associated with a patient. In an embodiment, the intra-oral x-ray sensor includes an intra-oral radiation shield structure configured to reduce at least one of x-ray scattering, transmission, or re-radiation by at least 50%. For example, in an embodiment, oral x-ray sensor includes an intra-oral radiation shield structure having one or more high-atomic number (high-Z) materials in an amount sufficient to reduce at least one of x-ray scattering, transmission, or re-radiation by at least 50%. In an aspect, the present disclosure is directed to, among other things, an intra-oral x-ray sensor. In an embodiment, the intra-oral x-ray sensor includes circuitry configured to communicate intra-oral x-ray sensor position information to a remote x-ray source. In an embodiment, the circuitry configured to communicate intra-oral x-ray sensor position information to the remote x-ray source includes one or more wired or wireless connections to the remote x-ray source. In an embodiment, the intra-oral x-ray sensor includes circuitry configured to communicate intra-oral x-ray sensor orientation information to the remote x-ray source. In an embodiment, the intra-oral x-ray sensor includes circuitry configured to verify an x-ray beam characteristic associated with the remote x-ray source. In an embodiment, the intra-oral x-ray sensor includes circuitry configured to communicate an x-ray beam field of view parameter to the remote x-ray source responsive to verifying an x-ray beam characteristic. In an embodiment, the intra-oral x-ray sensor includes circuitry configured to determine remote x-ray source and intra-oral x-ray sensor alignment before communicating an activation instruction to the remote x-ray source for imaging. In an embodiment, the intra-oral x-ray sensor includes circuitry configured to acquire a low intensity x-ray pulse to determine remote x-ray source and intra-oral x-ray sensor alignment before communicating an activation instruction to the remote x-ray source for imaging. In an aspect, the present disclosure is directed to, among other things, an intra-oral x-ray sensor operation method. In an embodiment, the intra-oral x-ray sensor operation method includes communicating intra-oral x-ray sensor position information to a remote x-ray source. In an embodiment, the intra-oral x-ray sensor operation method includes communicating intra-oral x-ray sensor orientation information to a remote x-ray source. In an embodiment, the intra-oral x-ray sensor operation method includes verifying an x-ray beam characteristic associated with the remote x-ray source. In an embodiment, the intra-oral x-ray sensor operation method includes communicating an x-ray beam field of view parameter to the remote x-ray source responsive to verifying an x-ray beam characteristic. In the following detailed description, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be utilized, and other changes may be made, without departing from the spirit or scope of the subject matter presented here. Radiographs (e.g., intra-oral radiographs, panoramic radiographs, cephalo radiographs, etc.) are essential and valuable diagnostic tools in dentistry. An objective of dental radiography is to obtain the highest quality images possible, while keeping patients' exposure risk to a minimum. Exposure to radiation may cause cancer, birth defects in the children of exposed parents, and cataracts. A major concern is the delayed health effects arising from chronic cumulative exposure to radiation. One way to reduce a patient's radiation burden is to employ low-dose practices. FIGS. 1A and 1B show an intra-oral x-ray imaging system 100 in which one or more methodologies or technologies can be implemented such as, for example, reducing patient exposure to x-rays, reducing amount of scatter, transmission, or re-radiation during imaging, or improving x-ray image quality. In an embodiment, the intra-oral x-ray imaging system 100 includes one or more intra-oral x-ray sensors 102. In an embodiment, at least one of the one or more intra-oral x-ray sensors 102 is configured to acquire intra-oral x-ray image information 104 associated with a patient. In an embodiment, the intra-oral x-ray imaging system 100 includes an x-ray source 105 operably coupled to one or more intra-oral x-ray sensors 102. In an embodiment, the intra-oral x-ray imaging system 100 includes one or more power sources. In an embodiment, during operation, x rays from the x-ray source 105 pass through the body of the patient striking hard and soft tissue. In an embodiment, a portion of the x-ray beam is deflected, a portion of the x-ray beam is scattered, a portion of the x-ray beam is absorbed, a portion triggers release of characteristic radiation, etc. Intra-oral x-ray image information (e.g., diagnostic dental x rays) is acquired by positioning a part of the body to be examined between a focused x-ray beam and the intra-oral x-ray sensors 102. In an embodiment, the intra-oral x-ray imaging system 100 includes one or more modules. For example, in an embodiment, the intra-oral x-ray imaging system 100 includes x-ray collimator module 106. In an embodiment, the collimator module 106 is operably coupled to an intra-oral x-ray sensor 102 and an x-ray beam limiter assembly 108. For example, in an embodiment, the collimator module 106 is operably coupled to an intra-oral x-ray sensor 102 via a wired or wireless connection 103. In an embodiment, the x-ray beam limiter assembly 108 includes a controllable x-ray collimator module 106. In an embodiment, the controllable x-ray collimator module 106 includes an x-ray beam collimation adjustment mechanism that is responsive to one or more inputs including information associated with a border position of the intra-oral sensor 102. For example, in an embodiment, the x-ray collimator module 106 is configured to vary a shutter aperture 114 associated with at least one of the one or more shutters responsive one or more inputs including information associated with a position of the intra-oral sensor 102, a border position of the intra-oral sensor 102, a position of an intra-oral x-ray sensor centroid, or the like. In an embodiment, a module includes, among other things, one or more computing devices such as a processor (e.g., a microprocessor), a central processing unit (CPU), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), or the like, or any combinations thereof, and can include discrete digital or analog circuit elements or electronics, or combinations thereof. In an embodiment, a module includes one or more ASICs having a plurality of predefined logic components. In an embodiment, a module includes one or more FPGAs, each having a plurality of programmable logic components. In an embodiment, the x-ray collimator module 106 includes a module having one or more components operably coupled (e.g., communicatively, electromagnetically, magnetically, ultrasonically, optically, inductively, electrically, capacitively coupled, or the like) to each other. In an embodiment, a module includes one or more remotely located components. In an embodiment, remotely located components are operably coupled, for example, via wireless communication. In an embodiment, remotely located components are operably coupled, for example, via one or more receivers, transmitters, transceivers, antennas, or the like. In an embodiment, the x-ray collimator module 106 includes a module having one or more routines, components, data structures, interfaces, and the like. In an embodiment, a module includes memory that, for example, stores instructions or information. For example, in an embodiment, the x-ray collimator module 106 includes memory that stores, for example, one or more of intra-oral x-ray sensor border position information, intra-oral x-ray sensor centroid information, intra-oral x-ray sensor dimension information, intra-oral x-ray sensor orientation information, intra-oral x-ray sensor position information, intra-oral x-ray sensor specific collimation information, or the like. For example, in an embodiment, the x-ray collimator module 106 includes memory that, for example, stores reference collimation information (e.g., reference collimation shape information, reference collimation size information, reference collimation separation information, etc.), intra-oral x-ray sensor position or orientation information, x-ray image information associated with a patient, or the like. Non-limiting examples of memory include volatile memory (e.g., Random Access Memory (RAM), Dynamic Random Access Memory (DRAM), or the like), non-volatile memory (e.g., Read-Only Memory (ROM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Compact Disc Read-Only Memory (CD-ROM), or the like), persistent memory, or the like. Further non-limiting examples of memory include Erasable Programmable Read-Only Memory (EPROM), flash memory, or the like. In an embodiment, the memory is coupled to, for example, one or more computing devices by one or more instructions, information, or power buses. For example, in an embodiment, the x-ray collimator module 106 includes memory that, for example, stores reference collimation information (e.g., reference collimation shape information, reference collimation size information, reference collimation separation information, etc.), intra-oral x-ray sensor position or orientation information, x-ray image information associated with a patient, or the like. In an embodiment, a module includes one or more computer-readable media drives, interface sockets, Universal Serial Bus (USB) ports, memory card slots, or the like, and one or more input/output components such as, for example, a graphical user interface, a display, a keyboard, a keypad, a trackball, a joystick, a touch-screen, a mouse, a switch, a dial, or the like, and any other peripheral device. In an embodiment, a module includes one or more user input/output components, user interfaces, or the like, that are operably coupled to at least one computing device configured to control (electrical, electromechanical, software-implemented, firmware-implemented, or other control, or combinations thereof) at least one parameter associated with, for example, controlling activating, operating, or the like, an x-ray beam limiter assembly 108. In an embodiment, a module includes a computer-readable media drive or memory slot that is configured to accept signal-bearing medium (e.g., computer-readable memory media, computer-readable recording media, or the like). In an embodiment, a program for causing a system to execute any of the disclosed methods can be stored on, for example, a computer-readable recording medium (CRMM), a signal-bearing medium, or the like. Non-limiting examples of signal-bearing media include a recordable type medium such as a magnetic tape, floppy disk, a hard disk drive, a Compact Disc (CD), a Digital Video Disk (DVD), Blu-Ray Disc, a digital tape, a computer memory, or the like, as well as transmission type medium such as a digital or an analog communication medium (e.g., a fiber optic cable, a waveguide, a wired communications link, a wireless communication link (e.g., receiver, transmitter, transceiver, transmission logic, reception logic, etc.). Further non-limiting examples of signal-bearing media include, but are not limited to, DVD-ROM, DVD-RAM, DVD+RW, DVD-RW, DVD-R, DVD+R, CD-ROM, Super Audio CD, CD-R, CD+R, CD+RW, CD-RW, Video Compact Discs, Super Video Discs, flash memory, magnetic tape, magneto-optic disk, MINIDISC, non-volatile memory card, EEPROM, optical disk, optical storage, RAM, ROM, system memory, web server, or the like. In an embodiment, the x-ray collimator module 106 is configured to adjust an x-ray beam field of view responsive to one or more inputs including information associated with a border position of the intra-oral sensor 102. For example, in an embodiment, the intra-oral x-ray imaging system 100 includes an x-ray beam limiter assembly 108 having at least one collimator 110. In an embodiment, the collimator 110 includes a barrier 112 with a variable aperture 114 configured to vary the size and shape of an x-ray beam so as to substantially match the size of an intra-oral x-ray sensor detection region 126a (shown in FIG. 2B). In an embodiment, the collimator 110 implements filtration and collimation techniques and methodologies that reduce a patient's radiation burden. For example, in an embodiment, during operation, activation of the collimator 110 results in a reduction of the size and shape of the x-ray beam, resulting in a reduction of the volume of irradiated tissue in the patient. In an embodiment, activation of the collimator 110 also results in the elimination of one or more divergent portion of an x-ray beam. In an embodiment, the x-ray collimator module 106 is operably coupled to the intra-oral x-ray sensor 102 and the x-ray beam limiter assembly 108, and is configured to adjust an x-ray beam field of view responsive to one or more inputs from the intra-oral x-ray sensor 102 indicative of a border position of the intra-oral sensor 102. The variation of the x-ray beam field of view can comprise a change in the beam size, the beam shape, the beam orientation, or the like. In an embodiment, the x-ray beam expands as it propagates from the x-ray beam limiter assembly 108 towards the patient and the intra-oral x-ray sensor 102. For example, the x-ray propagation can be calculated by assuming straight line x-ray trajectories, allowing the propagation and expansion of the beam to be calculated by knowledge of the relative positions of the x-ray source 105 (e.g., internal components such as an x-ray beam emitter and elements of the x-ray beam limiter assembly 108) and the intra-oral x-ray sensor 102. In an embodiment, the x-ray collimator module 106 is configured to adjust the x-ray beam field of view such that a border position of the expanding x-ray substantially corresponds (e.g., matches, minimizes overfilling, minimizes underfilling, substantially fills the sensor area, etc.) to a border position of the intra-oral x-ray sensor 102 as the propagating beam arrives at it. In an embodiment, the intra-oral x-ray imaging system 100 includes an x-ray beam limiter assembly 108 having an automatic aperture control mechanism including one or more mechanical diaphragms, (e.g., spring-loaded diaphragm, solenoid activated diaphragm, relay device activated diaphragm, electro-mechanical diaphragm, electromagnetic diaphragm, etc.) The mechanical diaphragm can include a plurality of aperture blades that interact with each other to create the aperture through which the x-rays are projected. In an embodiment, the x-ray collimator module 106 is configured to vary an aperture 114 associated with at least one of the one or more aperture blades included in a mechanical diaphragm responsive one or more inputs indicative of a position of the intra-oral sensor 102, a border position of the intra-oral sensor 102, a position of an intra-oral x-ray sensor centroid, or the like. In an embodiment, the x-ray collimator module 106 is configured to vary an aperture 114 associated with at least one of the one or more mechanical aperture diaphragms responsive one or more inputs indicative of an orientation of the intra-oral sensor 102. In an embodiment, the intra-oral x-ray imaging system 100 includes an x-ray beam limiter assembly 108 having one or more aperture diaphragms. In an embodiment, the x-ray collimator module 106 is configured to vary a diaphragm aperture of the one or more aperture diaphragms responsive to one or more inputs indicative of an orientation or a border position of the intra-oral sensor 102. The diaphragm adjusts the aperture blades to provide the appropriately sized and shaped aperture. In an embodiment, the intra-oral x-ray imaging system 100 includes an x-ray beam limiter assembly 108 having a collimator 110 including a collimator aperture. In an embodiment, the collimator aperture shape can be a geometrical shape including and regular geometric shapes, such as circular, rectangular, triangular, or the like, as well as irregular geometric shapes. In an embodiment, the intra-oral x-ray imaging system 100 includes an x-ray beam limiter assembly 108 including one or more blades, radiation source shutters, wedges, and the like. In an embodiment, the x-ray collimator module 106 is configured to adjust the x-ray beam field size by actuating a change in a separation distance between a collimator aperture and an x-ray source 105 responsive to one or more inputs including information associated with an orientation or a border position of the intra-oral sensor 102. For example, in an embodiment, the x-ray collimator module 106 is operably coupled to a separation distance adjustment mechanism responsive to one or more inputs including information associated with an orientation or a border position of the intra-oral sensor 102. In an embodiment, the x-ray collimator module 106 is operably coupled to a collimator-and-x-ray source assembly configured to adjust the x-ray beam field size by actuating a change in a separation distance between a collimator aperture and an x-ray source 105 responsive to one or more inputs including information associated with an orientation or a border position of the intra-oral sensor 102. In an embodiment, the x-ray beam limiter assembly 108 includes a primary collimator and a secondary collimator. In an embodiment, the x-ray beam limiter assembly 108 includes a variable aperture collimator. In an embodiment, the intra-oral x-ray imaging system 100 includes an x-ray beam limiter assembly 108 having a plurality of selectively actuatable absorber blades configured to form a focal plane shutter. In an embodiment, the focal plane shutter is positioned immediately or right in front of the intra-oral sensor 102. In an embodiment, the focal plane shutter is positioned immediately or right in front of a film-based analog x-ray sensor, a dental digital x-ray sensor, a charge-coupled device (CCD) sensor, complementary metal-oxide-semiconductor (CMOS) sensor, and the like. In an embodiment, the x-ray collimator module 106 is configured to adjust the x-ray beam field size by actuating one or more of the plurality of selectively actuatable absorber blades responsive one or more inputs including information associated with an orientation or a border position of the intra-oral sensor 102. In an embodiment, the intra-oral x-ray imaging system 100 includes an x-ray beam limiter assembly 108 configured to adjust an x-ray beam field size. In an embodiment, the intra-oral x-ray imaging system 100 includes an x-ray beam limiter assembly 108 configured to reduce the size of the x-ray beam at the point of contact with the intra-oral sensor to the size of the intra-oral sensor 102 detection area so as to reduce a patient exposure to x-rays. In an embodiment, the x-ray beam limiter assembly 108 includes one or more aperture diaphragms. In an embodiment, the x-ray beam limiter assembly 108 includes one or more circular aperture diaphragms having mechanical extensions (e.g., aperture blades, radiation source shutters, wedges, etc.) configured to form part of a focal plane shutter. In an embodiment, the x-ray beam limiter assembly 108 includes a shutter assembly having one or more opposing pair shutters. In an embodiment, the x-ray beam limiter assembly 108 includes at least a first-stage shutter and a second-stage shutter. In an embodiment, the intra-oral sensor 102 is configured to work together with the x-ray source 105 to reduce unnecessary patient exposure to x-rays. For example, in an embodiment, the x-ray beam limiter assembly 108 includes an aperture shaped and sized to direct an x-ray beam that provides a beam area that coincides with the detector area of the intra-oral sensor 102. During operation, the x-ray emitter and the intra-oral sensor 102 placed in the patient's mouth may not align exactly, resulting in an x-ray beam projection that is too big, too small, misoriented, etc. In an embodiment, this is fixed by translating or rotating an aperture or by translating or rotating the x-ray emitter. In an embodiment, the x-ray beam limiter assembly 108 includes at least one x-ray beam-limiting aperture configured to translate (laterally and/or longitudinally) relative to an x-ray emitter. In an embodiment, the x-ray beam limiter assembly 108 includes at least one x-ray beam-limiting aperture configured to rotate relative to an x-ray emitter. In an embodiment, the x-ray beam limiter assembly 108 includes at least one x-ray emitter configured to translate (laterally and/or longitudinally) relative to an x-ray beam-limiting aperture. In an embodiment, the x-ray beam limiter assembly 108 includes one or more diaphragms formed from high atomic number (high-Z) materials. For example, in an embodiment, the x-ray beam limiter assembly 108 includes one or more shutters formed from materials including elements have an atomic number greater than or equal to 37 (Rubidium or higher). In an embodiment, the x-ray beam limiter assembly 108 includes one or more shutters formed from materials including elements have an atomic number greater than or equal to 72 (Hathium or higher). In an embodiment, the x-ray beam limiter assembly 108 includes one or more x-ray filters. For example, in an embodiment, the intra-oral x-ray imaging system 100 includes an x-ray beam limiter assembly 108 including one or more x-ray compensating filters 117 such as a wedge 117a formed from aluminum, ceramic, high-density plastic, etc., that is placed over an oral cavity region during radiography to compensate for differences in radiopacity. In an embodiment, the x-ray compensating filter is configured to limit the x-rays passing through based upon the varying thickness of the filter. In an embodiment, the intra-oral x-ray imaging system 100 includes an x-ray beam limiter assembly 108 including one or more positive beam limitation devices configured to automatically collimate the x-ray beam to the size of the intra-oral x-ray sensor detection region at the point of contact with the intra-oral x-ray sensor 102. In an embodiment, the intra-oral x-ray imaging system 100 includes an x-ray beam limiter assembly 108 including one or more positive beam limitation devices configured to automatically collimate the x-ray beam so as to substantially match the size of an intra-oral x-ray sensor detection region 126a (shown in FIG. 2B). In an embodiment, the x-ray beam limiter assembly 108 includes an extension cone or an extension cylinder. In an embodiment, the x-ray collimator module 106 is configured to interface with one or more components via one or more wired or wireless connections. For example, in an embodiment, the x-ray collimator module 106 is in wireless communication with the x-ray beam limiter assembly 108. In an embodiment, the x-ray collimator module 106 is operably coupled to the x-ray beam limiter assembly 108 via one or more wired connections. In an embodiment, the x-ray collimator module 106 is in wireless communication with the intra-oral x-ray sensor 102. In an embodiment, the x-ray collimator module 106 is in wireless communication with an x-ray source 105. In an embodiment, the intra-oral x-ray sensor 102 is in wireless communication with an x-ray source 105. In an embodiment, the x-ray collimator module 106 is configured to adjust the x-ray beam field size responsive to the one or more inputs, such as one or more inputs including information associated with a location of a corner position of the intra-oral x-ray sensor 102. In an embodiment, the x-ray collimator module 106 is configured to adjust the x-ray beam field size responsive to the one or more inputs including information associated with a location of an edge position of the intra-oral x-ray sensor 102. In an embodiment, the x-ray collimator module 106 is configured to adjust the x-ray beam field size responsive to the one or more inputs including information associated with a location of a reference position on the intra-oral x-ray sensor 102 having a specified offset from a corner of the intra-oral x-ray sensor 102. In an embodiment, the x-ray collimator module 106 is configured to adjust the x-ray beam field size responsive to the one or more inputs including information associated with a location of a reference position on the intra-oral x-ray sensor having a specified offset from an edge of the intra-oral x-ray sensor 102. In an embodiment, the x-ray collimator module 106 is configured to adjust the x-ray beam field size responsive to the one or more inputs including information associated with an edge orientation of the intra-oral x-ray sensor 102. In an embodiment, the x-ray collimator module 106 is configured to adjust the x-ray beam field size responsive to one or more inputs from the x-ray collimator module 106 indicative of an intra-oral x-ray sensor position or orientation. In an embodiment, the position and/or orientation of the intra-oral x-ray sensor is determined relative to the position and/or orientation of at least one of the x-ray source 105, the collimator module 106, the x-ray beam limiter assembly 108, an x-ray beam emitter, and an external reference point. For example, in an embodiment, during operation, the x-ray collimator module 106 is configured to adjust the x-ray beam field size responsive to one or more inputs from the x-ray collimator module 106 indicative of an intra-oral x-ray sensor border position. In an embodiment, during operation, the x-ray collimator module 106 is configured to adjust the x-ray beam field size responsive to one or more inputs from the x-ray collimator module 106 indicative of an intra-oral x-ray sensor centroid 126 position. In an embodiment, during operation, the x-ray collimator module 106 is configured to adjust the x-ray beam field size responsive to one or more inputs from the x-ray collimator module 106 indicative of an intra-oral x-ray sensor angular orientation. In an embodiment, the x-ray collimator module 106 is configured to adjust the x-ray beam field size responsive to one or more inputs from the x-ray collimator module 106 indicative of an intra-oral x-ray sensor dimension. In an embodiment, the x-ray collimator module 106 is configured to generate one or more parameters associated with an x-ray beam limiter assembly 108 configuration responsive to one or more inputs from an intra-oral x-ray sensor 102. In an embodiment, the x-ray collimator module 106 is configured to generate at least one parameter associated with an x-ray imaging mode (e.g., adult panoramic mode, child panoramic mode, high-dose-rate mode, low-dose-rate mode, moderate-dose-rate mode mandible mode, occlusion mode, maxillary mode, panoramic mode, pulsed fluoroscopy mode, temporomandibular joint mode, etc.) responsive to one or more inputs from an intra-oral x-ray sensor 102. In an embodiment, the intra-oral x-ray imaging system 100 includes a field of view module 107 operable to generate one or more parameters associated with a field of view setting (e.g., field of view size, field of view shape, wide field of view, narrow field of view, field of view extension, horizontal field of view, vertical field of view, diagonal field of view, magnification, increase, decrease, etc.) responsive to one or more inputs from the x-ray collimator module 106 indicative of an intra-oral x-ray sensor position, orientation, or the like. In an embodiment, the intra-oral x-ray imaging system 100 includes one or more intra-oral x-ray sensors 102 configured to acquire intra-oral x-ray image information 104 associated with a patient. In an embodiment, the intra-oral x-ray imaging system 100 includes an x-ray image component 116 operably coupled to one or more intra-oral x-ray sensors 102. Non-limiting examples of intra-oral x-ray sensors 102 include film-based analog x-ray sensors, dental digital x-ray sensors, charge-coupled device (CCD) sensors, complementary metal-oxide-semiconductor (CMOS) sensors, and the like. In an embodiment, the intra-oral x-ray imaging system 100 includes one or more intra-oral x-ray sensors 102 having at least one scintillator plate. In an embodiment, the intra-oral x-ray imaging system 100 includes one or more intra-oral x-ray sensors 102 having at least one scintillator layer. In an embodiment, a scintillator layer is vapor-deposited onto an optical fiber coupled to a photo-sensor integrated into a CCD or CMOS chip. Further non-limiting examples of intra-oral x-ray sensors 102 includes scintillators (e.g., inorganic scintillators, thallium doped cesium iodide scintillators, scintillator-photodiode pairs, scintillation detection devices, etc.), dosimeters (e.g., x-ray dosimeters, thermoluminescent dosimeters, etc.), optically stimulated luminescence detectors, photodiode arrays, charge-coupled devices (CCDs), complementary metal-oxide-semiconductor (CMOS) devices, or the like. In an embodiment, the intra-oral x-ray sensor 102 includes one or more transducers that detect and convert x-rays into electronic signals. For example, in an embodiment, the intra-oral x-ray sensor 102 includes one or more x-ray radiation scintillation crystals. In an embodiment, the intra-oral x-ray sensor 102 includes one or more thallium doped cesium iodide crystals (e.g., cesium iodide crystals doped with thallium CsI(Tl)). In an embodiment, during operation the intra-oral x-ray sensor 102 includes a computing device that processes the electronic signals generated by the one or more transducers to determine one or more of intensity, energy, time of exposure, date of exposure, exposure duration, rate of energy deposition, depth of energy deposition, and the like associated with each x-ray detected. In an embodiment, during operation, incident x-ray radiation interacts with one or more detector crystalline materials (e.g., cadmium zinc telluride, etc.) within the intra-oral x-ray sensor 102, which results in the generation of a current indicative of, for example, the energy of the incident x-ray radiation. In an embodiment, the intra-oral x-ray sensor 102 includes an amorphous-carbon substrate coupled to a Cesium Iodide (CsI) scintillator. In an embodiment, the intra-oral x-ray sensor 102 includes a fiber optic plate (FOP) coupled to a CsI scintillator. In an embodiment, the intra-oral x-ray sensor 102 includes an aluminum substrate coupled to a CsI scintillator. In an embodiment, the intra-oral x-ray sensor 102 includes a scintillator configured to reduce scattering. For example, in an embodiment, the intra-oral x-ray sensors 102 includes thallium-doped-Cesium Iodide (CsI:TI) having columnar structure deposited on a substrate operably coupled to a CMOS/CCD sensor. See e.g., Zhao et al. X-ray imaging performance of structured cesium iodide scintillators. Med. Phys. 31, 2594-2605 (2004) which is incorporated herein by reference. The columnar structure of CsI helps to selectively pass a portion of the x-ray bean onto a CMOS/CCD sensor forming part of the intra-oral x-ray sensor 102. In an embodiment, the intra-oral x-ray sensor 102 includes a substrate that acquires at least a portion of penetrating x-ray radiation stimulus and transduces the penetrating x-ray radiation stimulus acquired by the intra-oral x-ray sensor 102 into an image or at least one measurand indicative of an x-ray flux throughput during an integration period of the intra-oral x-ray sensor 102. In an embodiment, an x-ray image component 116 component is operably coupled to an intra-oral x-ray sensor 102 having one or more x-ray radiation fluoroscopic elements. In an embodiment, the intra-oral x-ray sensor 102 includes one or more phosphorus doped elements (e.g., ZnCdS:Ag phosphorus doped elements). In an embodiment, the intra-oral x-ray sensor 102 includes one or more amorphous silicon thin-film transistor arrays. In an embodiment, the intra-oral x-ray sensor 102 includes one or more phosphors. In an embodiment, the x-ray image component 116 is operably coupled to one or more active pixel image sensors. In an embodiment, the x-ray image component 116 is operably coupled to one or more complementary metal-oxide-semiconductor sensors. In an embodiment, the x-ray image component 116 is operably coupled to one or more complementary metal-oxide-semiconductor active pixel sensors. In an embodiment, the intra-oral x-ray imaging system 100 includes at least one intra-oral x-ray sensor 102 wirelessly coupled to the x-ray collimator module 106. In an embodiment, the intra-oral x-ray imaging system 100 includes at least one intra-oral x-ray sensor 102 wired or wirelessly coupled to an x-ray source 105. In an embodiment, the intra-oral x-ray imaging system 100 includes an intra-oral x-ray sensor module 109 operably coupled to the intra-oral x-ray sensor 102 and the x-ray collimator module. In an embodiment, the intra-oral x-ray sensor module 109 is configured to generate one or more of intra-oral x-ray sensor dimension information, intra-oral x-ray sensor orientation information, or intra-oral x-ray sensor position information responsive to one or more inputs from the x-ray image sensor 102 or the x-ray collimator module 106. In an embodiment, the x-ray collimator module 106 is in wireless communication with the intra-oral x-ray sensor module. In an embodiment, during operation, the intra-oral x-ray imaging system 100 is configured to determine the position and orientation of the intra-oral x-ray sensor 102, and to adjust an x-ray beam field of view responsive to determining the position and orientation of the intra-oral x-ray sensor 102. For example, in an embodiment, the intra-oral x-ray imaging system 100 includes a camera, a sensor, a component, etc., configured to acquire image information associated with a position or an orientation of the intra-oral x-ray sensor 102. In an embodiment, the camera acquires an image involving one or more beacons 118, phosphors 120, retroreflectors 122, or the like that are configured to indicate the position or orientation of the intra-oral x-ray sensor 102. In an embodiment, the x-ray collimator module 106 is operably coupled to one or more sensors, components, etc., configured to determine, indicate, communicate, broadcast, etc., a border position of the intra-oral sensor 102. In an embodiment, the x-ray collimator module 106 is operably coupled to one or more beacons 118, phosphors 120, retroreflectors 122, or the like configured to determine, indicate, communicate, broadcast, etc., a border position of the intra-oral sensor 102. For example, during operation, the x-ray collimator module 106 is configured to acquire one or more inputs from one or more beacons 118 indicative of the position or orientation of the intra-oral x-ray sensor 102. In an embodiment, during operation, the x-ray collimator module 106 is configured to acquire one or more electrical, acoustic, or electromagnetic inputs from one or more beacons 118 indicative of the position or orientation of the intra-oral x-ray sensor 102. In an embodiment, during operation, the x-ray collimator module 106 is configured to acquire one or more inputs from a sensor configure to detect a florescence associated with one or more phosphors 120, and to generate information indicative of the position or orientation of the intra-oral x-ray sensor 102 based on the one or more inputs from the sensor. In an embodiment, the x-ray collimator module 106 is operably coupled to one or more sensors configured to generate one or more outputs indicative of the position or orientation of the intra-oral x-ray sensor 102. In an embodiment, the x-ray collimator module 106 is operably coupled to one or retroreflectors configured to indicate the position or orientation of the intra-oral x-ray sensor 102. In an embodiment, the x-ray collimator module 106 is operably coupled to one or more beacons 118 configured to indicate, communicate, convey, etc., position information or orientation information associated with an intra-oral x-ray sensor 102. Non-limiting examples of beacons 118 include infrared emitters, ultraviolet emitters, visible emitters, electromagnetic energy emitters, ultrasound emitters, and the like. Further non-limiting examples of beacons 118 include magnetic field generators, inductors, capacitors, or the like. In an embodiment, during operation, the x-ray collimator module 106 adjusts an x-ray beam field of view responsive to detecting one or more emitted signals from a beacon 118. In an embodiment, the x-ray collimator module 106 is operably coupled to one or more beacons 118 configured to emit an ultrasonic output. In an embodiment, the x-ray collimator module 106 is operably coupled to one or more beacons 118 configured to emit an ultrasonic output that is detectable through tissue. In an embodiment, the x-ray collimator module 106 is operably coupled to one or more phosphors 120 configured to indicate the position or orientation of the intra-oral x-ray sensor 102. Non-limiting examples of phosphors 120 include infrared phosphors, ultraviolet phosphors, visible phosphors, x-ray phosphors, and the like. Further non-limiting examples of phosphors 120 include phosphors having a peak emission wavelength associated with an optical window in biological tissue. See e.g. J. Phys. D: Appl. Phys. 46 (2013) 375401 (5 pp) which is incorporated herein by reference. In an embodiment, the x-ray collimator module 106 is operably coupled to one or more phosphors 120 configured to provide a signal through the patient's skin (i.e. cheek, gum, or teeth). In an embodiment, the x-ray collimator module 106 is operably coupled to one or more phosphors 120 having a peak emission wavelength ranging from about 650 nanometers to about 900 nanometers. In an embodiment, during operation, the border position of the intra-oral sensor 102 is signaled by one or more phosphors 120. In an embodiment, during operation, the x-ray collimator module 106 adjusts an x-ray beam field of view responsive to detecting one or more phosphors 120 and determining a border position of the intra-oral sensor 102 based on determining the location of the one or more phosphors 120. In an embodiment, the intra-oral x-ray sensor comprises a position sensor 124 configured to determine border position data, and a transmitter configured to transmit a signal indicative of the border position data. In an embodiment, the border position data includes X, Y, and Z coordinates. In an embodiment, the border position data includes one or more parameters that define a specific location in a two-dimensional object or three-dimensional object. In an embodiment, the border position data includes one or more position parameters associated with an intra-oral x-ray sensor border. In an embodiment, the border position data includes one or more position parameters associated with an intra-oral x-ray sensor centroid 126. Non-limiting examples of position sensors 124 include local positioning system (e.g., analogous to GPS-type sensors) sensors configured to interact with room-based reference signals. In an embodiment, the position sensor 124 includes a magnetic sensor responding to room-based magnetic fields. In an embodiment, the position sensor 124 includes one or more accelerometer 128. In an embodiment, the position sensor 124 includes a multi-accelerometer or accelerometer-gyro package that keeps track of the motion involved in putting intra-oral x-ray sensor 102 into the patient's mouth. In an embodiment, the x-ray collimator module 106 is configured to adjust the x-ray beam to minimize the portion of the x-ray beam that misses (e.g., overfills) the intra-oral x-ray sensor 102. In an embodiment, the x-ray collimator module 106 is further configured to adjust the x-ray beam to maximize an amount of the x-ray beam that impacts the intra-oral x-ray sensor 102, e.g., to minimize underfilling it. FIG. 2A shows an intra-oral x-ray imaging device 200 in which one or more methodologies or technologies can be implemented such as, for example, reducing patient exposure to x-rays, reducing amount of scatter, transmission, or re-radiation during imaging, or improving x-ray image quality. In an embodiment, the intra-oral x-ray imaging device 200 includes circuitry 202 configured to determine a position and an orientation of an intra-oral x-ray sensor 102. In an embodiment, the circuitry 202 configured to determine the position and the orientation of the intra-oral x-ray sensor 102 includes circuitry configured to determine border position information of the intra-oral x-ray sensor 102. In an embodiment, the circuitry 202 configured to determine the position and the orientation of the intra-oral x-ray sensor 102 includes circuitry configured to determine an intra-oral x-ray sensor centroid position. In an embodiment, the circuitry 202 configured to determine the position and the orientation of the intra-oral x-ray sensor 102 includes an image sensor 203 configured to detect one or more optic devices 204 (e.g., retroreflectors, beacons, emitters, etc.) indicative of an intra-oral x-ray sensor border position, an intra-oral x-ray sensor position, or an intra-oral x-ray sensor orientation. In an embodiment, the circuitry 202 configured to determine the position and the orientation of the intra-oral x-ray sensor 102 is operably coupled to an embedded orientation detection component 206. In an embodiment, the circuitry 202 configured to determine the position and the orientation of the intra-oral x-ray sensor 102 and the one or more acoustic transducers 232 form part of an integrated component. In an embodiment, the circuitry 202 configured to determine the position and the orientation of the intra-oral x-ray sensor 102 is operably coupled to one or more magnetic compass based sensors 208. For example, in an embodiment, the circuitry 202 configured to determine the position and the orientation of the intra-oral x-ray sensor 102 is operably coupled to one or more embedded magnetic compass sensors 210. In an embodiment, the circuitry 202 configured to determine position and the orientation of the intra-oral x-ray sensor 102 and the one or more embedded magnetic compass sensors 210 form part of an integrated component. In an embodiment, the circuitry 202 configured to determine the position and the orientation of the intra-oral x-ray sensor 102 forms part of an integrated image sensor configured to detect one or more optic devices 204 (e.g., retroreflectors, beacons, emitters, etc.) In an embodiment, the circuitry 202 configured to determine the position and the orientation of the intra-oral x-ray sensor 102 is operably coupled to one or more local positioning system based sensors 124. In an embodiment, the circuitry 202 configured to determine the position and the orientation of the intra-oral x-ray sensor 102 is operably coupled to one or more acceleration sensors 214. In an embodiment, the circuitry 202 configured to determine the position and the orientation of the intra-oral x-ray sensor 102 is operably coupled to at least two acceleration sensors 214 in a substantially perpendicularly arrangement. In an embodiment, the circuitry 202 configured to determine the position and the orientation of the intra-oral x-ray sensor 102 is operably coupled to one or more multi-axis accelerometers 216. In an embodiment, the circuitry 202 configured to determine the position and the orientation of the intra-oral x-ray sensor 102 is operably coupled to one or more orientation-aware sensors 218. For example, in an embodiment, the circuitry 202 configured to determine the position and the orientation of the intra-oral x-ray sensor is operably coupled to one or more gyroscopes 220. In an embodiment, the circuitry 202 configured to determine the position and the orientation of the intra-oral x-ray sensor 102 is operably coupled to one or more electrolytic fluid based sensors 222. In an embodiment, the circuitry 202 configured to determine the position and the orientation of the intra-oral x-ray sensor 102 is operably coupled to a two-axis tilt sensor 224 configured to detect an intra-oral x-ray sensor roll or yaw angle. In an embodiment, the circuitry 202 configured to determine the position and the orientation of the intra-oral x-ray sensor 102 is operably coupled to a two-axis tilt sensor 224 configured to detect an intra-oral x-ray sensor pitch angle. In an embodiment, the circuitry 202 configured to determine the position and the orientation of the intra-oral x-ray sensor 102 is operably coupled to one or more inductors 226. In an embodiment, the circuitry 202 configured to determine the position and the orientation of the intra-oral x-ray sensor 102 is operably coupled to one or more active optic devices 228. For example, in an embodiment, the circuitry 202 configured to determine the position and the orientation of the intra-oral x-ray sensor 102 is operably coupled to one or more optical emitter that emit an electromagnetic energy signal that provides information associated with the position and the orientation of the intra-oral x-ray sensor 102. In an embodiment, the circuitry 202 configured to determine the position and the orientation of the intra-oral x-ray sensor 102 is operably coupled to one or more active acoustic emitters. In an embodiment, the circuitry 202 configured to determine the position and the orientation of the intra-oral x-ray sensor 102 is operably coupled to one or more passive optics devices 230 (e.g., retroreflectors, phosphors, etc.). In an embodiment, during operation, the circuitry 202 configured to determine the position and the orientation of the intra-oral x-ray sensor 102 by emitting an interrogation signal that is reflected back by the one or more retroreflectors. The reflected signal is use to generate information associated with the position and the orientation of the intra-oral x-ray sensor 102. In an embodiment, the circuitry 202 configured to determine the position and the orientation of the intra-oral x-ray sensor 102 is operably coupled to one or more acoustic transducers 232 configured to generate an output indicative of an intra-oral x-ray sensor border position and an intra-oral x-ray sensor orientation. In an embodiment, the circuitry 202 configured to determine the position and the orientation of the intra-oral x-ray sensor 102 and the one or more acoustic transducers 232 form part of an integrated component. In an embodiment, the intra-oral x-ray sensor 102 includes an integrated component including one or more optic devices 204, orientation detection component 206, magnetic compass based sensors 208, embedded magnetic compass sensors 210, local positioning system based sensors 124, more acceleration sensors 214, multi-axis accelerometers 216, orientation-aware sensors 218, gyroscopes 220, electrolytic fluid based sensors 222, two-axis tilt sensors 224, inductors 226, optic devices 228, passive optics devices 230, acoustic transducers 232, or the like. In an embodiment, the intra-oral x-ray imaging device 200 includes circuitry 234 configured to adjust an x-ray beam field of view (FOV) responsive to one or more inputs from the circuitry 202 configured to determine the position and the orientation of the intra-oral x-ray sensor 102. For example, in an embodiment, the circuitry 234 configured to adjust the x-ray beam field of view is operably coupled to at least one of the x-ray collimator module 106 or the x-ray beam limiter assembly 108, and is configured to generate one or more control signal that actuates the x-ray collimator module 106 or the x-ray beam limiter assembly 108 to adjust an x-ray beam FOV responsive to one or more inputs from the circuitry 202 configured to determine the position and the orientation of the intra-oral x-ray sensor 102. In an embodiment, the intra-oral x-ray imaging device 200 includes circuitry 236 configured to acquire intra-oral x-ray image information associated with a patient. In an embodiment, the intra-oral x-ray imaging device 200 includes circuitry 238 configured to generate one or more parameters associated with a field of view setting. In an embodiment, the circuitry 238 configured to generate one or more parameters associated with a field of view setting includes circuitry configured to generate the one or more parameters associated with the field of view setting responsive to one or more inputs from the circuitry 202 configured to determine the position and the orientation of the intra-oral x-ray sensor 102. FIG. 3A shows an intra-oral x-ray sensor 102 in which one or more methodologies or technologies can be implemented such as, for example, reducing patient exposure to x-rays, reducing amount of scatter, transmission, or re-radiation during imaging, or improving x-ray image quality. In an embodiment, the intra-oral x-ray sensor 102 includes an x-ray image component 116 configured to acquire intra-oral x-ray image information 104 associated with a patient. In an embodiment, the x-ray image component 116 includes circuitry 236 configured to acquire intra-oral x-ray image information associated with a patient. In an embodiment, the intra-oral x-ray sensor 102 includes an intra-oral radiation shield structure 302 configured to reduce at least one of x-ray scattering, transmission, or re-radiation by at least 50%. In an embodiment, the intra-oral radiation shield structure 302 includes one or more high atomic number (high-Z) materials in an amount sufficient to reduce at least one of x-ray scattering, transmission, or re-radiation by at least 50%. For example, in an embodiment, at least a portion of the intra-oral radiation shield structure 302 is formed from materials including elements have an atomic number greater than or equal to 37 (Rubidium or higher). In an embodiment, at least a portion of the intra-oral radiation shield structure 302 is formed from materials including elements have an atomic number greater than or equal to 72 (Hathium or higher). In an embodiment, the intra-oral radiation shield structure 302 includes one or more materials having a K-edge greater than 15 kiloelectron volts in an amount sufficient to reduce at least one of x-ray scattering, transmission, or re-radiation by at least 50%. Non-limiting examples of materials having a K-edge greater than 15 kiloelectron volts include elements have an atomic number greater than or equal to 37 (Rubidium or higher). In an embodiment, the intra-oral radiation shield structure 302 includes one or more materials having an L-edge greater than 10 kiloelectron volts in an amount sufficient to reduce at least one of x-ray scattering, transmission, or re-radiation by at least 50%. Non-limiting examples of materials having an L-edge greater than 10 kiloelectron volts include elements have an atomic number greater than or equal to 69 (Thulium or higher). In an embodiment, the intra-oral radiation shield structure 302 includes a mixture of materials having a K-edge greater than 15 kiloelectron volts, materials having an L-edge greater than 10 kiloelectron volts, or high atomic number (high-Z) materials in an amount sufficient to reduce at least one of x-ray scattering, transmission, or re-radiation by at least 50%. Referring to FIG. 3B, in an embodiment, the intra-oral x-ray sensor 102 includes a laminate structure having multiple layers. For example, in an embodiment, the intra-oral x-ray sensor 102 includes one or more of radiation shield layers 304, 306, electronic circuit layers 308, sensor layers 310, scintillator layers 312, protection layers 314, etc. In an embodiment, the intra-oral radiation shield structure 302 includes a laminate structure having at least a first layer 304. In an embodiment, the intra-oral radiation shield structure 302 includes a laminate structure having at least a first layer 304 and a second layer 306, the second layer having an x-ray attenuation profile different from the first layer. In an embodiment, the intra-oral radiation shield structure 302 includes a laminate structure having at least a first layer 304 and a second layer 306, the second layer 306 having an attenuation coefficient different from the first layer 304. In an embodiment, at least a portion of the intra-oral radiation shield structure 302 is composed of one or more x-ray shielding materials. In an embodiment, at least a portion of the intra-oral radiation shield structure 302 is composed of one or more x-ray radio-opaque materials (e.g., barium sulfate, silicon carbide, silicon nitride, alumina, zirconia, etc.). In an embodiment, at least a portion of the intra-oral radiation shield structure 302 is composed of one or more x-ray attenuating materials. In an embodiment, at least a portion of the intra-oral radiation shield structure 302 is composed of one or more x-ray attenuating ceramic materials. In an embodiment, at least a portion of the intra-oral radiation shield structure 302 is composed of multiple layers, each layer having an xx-ray attenuation coefficient different from another. In an embodiment, at least a portion of the intra-oral radiation shield structure 302 is composed of one or more ferromagnetic materials. Ferromagnetic materials include those materials having a Curie temperature, above which thermal agitation destroys the magnetic coupling giving rise to the alignment of the elementary magnets (electron spins) of adjacent atoms in a lattice (e.g., a crystal lattice). In an embodiment, one or more of the plurality of x-ray shielding particles include one or more ferromagnets. Non-limiting examples ferromagnetic materials include crystalline ferromagnetic materials, ferromagnetic oxides, materials having a net magnetic moment, materials having a positive susceptibility to an external magnetic field, non-conductive ferromagnetic materials, non-conductive ferromagnetic oxides, ferromagnetic elements (e.g., cobalt, gadolinium, iron, or the like), rare earth elements, ferromagnetic metals, ferromagnetic transition metals, materials that exhibit magnetic hysteresis, and the like, and alloys or mixtures thereof. Further non-limiting examples of ferromagnetic materials include chromium (Cr), cobalt (Co), copper (Cu), dysprosium (Dy), europium (Eu), gadolinium (Gd), iron (Fe), magnesium (Mg), neodymium (Nd), nickel (Ni), yttrium (Y), and the like. Further non-limiting examples of ferromagnetic materials include chromium dioxide (CrO2), copper ferrite (CuOFe2O3), europium oxide (EuO), iron(II, III) oxide (FeOFe2O3), iron(III) oxide (Fe2O3), magnesium ferrite (MgOFe2O3), manganese ferrite (MnOFe2O3), nickel ferrite (NiOFe2O3), yttrium-iron-garnet (Y3Fe5O12), and the like. Further non-limiting examples of ferromagnetic materials include manganese arsenide (MnAs), manganese bismuth (MnBi), manganese (III) antimonide (MnSb), Mn—Zn ferrite, neodymium alloys, neodymium, Ni—Zn ferrite, and samarium-cobalt. In an embodiment, at least a portion of the intra-oral radiation shield structure 302 is composed of iron oxides. Non-limiting examples of iron oxides include copper ferrite (CuOFe2O3), iron(II, III) oxide (FeOFe2O3), iron(III) oxide (Fe2O3), magnesium ferrite (MgOFe2O3), manganese ferrite (MnOFe2O3), nickel ferrite (NiOFe2O3), yttrium-iron-garnet (Y3Fe5O12), ferric oxides, ferrous oxides, and the like. In an embodiment, one or more of the plurality of x-ray shielding particles include at least one iron oxide. In an embodiment, at least a portion of the intra-oral radiation shield structure 302 is composed of one or ferrimagnetic materials. In an embodiment, one or more of the plurality of x-ray shielding particles include one or more ferrimagnets (e.g., soft ferrites, hard ferrites, or the like). Non-limiting examples of ferrimagnetic materials include ferrimagnetic oxides (e.g., ferrites, garnets, or the like). Further non-limiting examples of ferrimagnetic materials include ferrites with a general chemical formula of AB2O4 (e.g., CoFe2O4, MgFe2O4, ZnFe2O4) where A and B represent various metal cations. In an embodiment, A is Mg, Zn, Mn, Ni, Co, or Fe(II); B is Al, Cr(III), Mn(III) or Fe(III), and O is oxygen. In an embodiment, A is a divalent atom of radius ranging from about 80 pm to about 110 pm (e.g., Cu, Fe, Mg, Mn, Zn, or the like), B is a trivalent atom of radius ranging from about 75 pm to about 90 pm, (e.g., Al, Fe, Co, Ti, or the like), and O is oxygen. Non-limiting examples of ferrimagnetic materials include iron ferrites with a general chemical formula MOFe2O3 (e.g., CoFe2O4, Fe3O4, MgFe2O4, or the like) where M is a divalent ion such as Fe, Co, Cu, Li, Mg, Ni, or Zn. In an embodiment, at least a portion of the intra-oral radiation shield structure 302 is composed of at least a first ferrimagnetic material and a second ferromagnetic material, the second ferrimagnetic material having one or more absorption edges different from the first ferrimagnetic material. In an embodiment, the intra-oral radiation shield structure 302 includes a laminate structure having at least a first layer 304 and a second layer 306, the second layer having a different ferrimagnetic material composition from the first layer. Non-limiting examples of ferrimagnetic materials include materials having a magnetization compensation point, materials that are associated with a partial cancellation of antiferromagnetically aligned magnetic sublattices with different values of magnetic moments, or material having different temperature dependencies of magnetization. See e.g., Kageyama et al., Weak Ferrimagnetism, Compensation Point, and Magnetization Reversal in Ni(HCOO)2.2H2O, Physical Rev. B, 224422 (2003). In an embodiment, at least a portion of the intra-oral radiation shield structure 302 comprises one or more paramagnetic materials. In an embodiment, the intra-oral radiation shield structure 302 is removably attachable to the intra-oral x-ray sensor 102. For example, in an embodiment, at least a portion of the intra-oral radiation shield structure 302 is removably attachable to the intra-oral x-ray sensor 102, behind a sensor layer 310. In an embodiment, at least a portion of the intra-oral radiation shield structure 302 includes two or more layers secured to each other to form structure 302. In an embodiment, at least a portion of the intra-oral radiation shield structure 302 is composed of one or more x-ray radio-opaque materials. In an embodiment, at least a portion of the intra-oral radiation shield structure 302 is composed of one or more x-ray attenuating materials. In an embodiment, at least a portion of the intra-oral radiation shield structure 302 is composed of one or more x-ray attenuating ceramic materials. In an embodiment, at least a portion of the intra-oral radiation shield structure 302 is composed of at least a first x-ray radio-opaque material and a second x-ray radio-opaque material, the second x-ray radio-opaque material having a different x-ray opacity profile from the first x-ray radio-opaque material. In an embodiment, the intra-oral radiation shield structure 302 includes a laminate structure having at least a first layer 304 and a second layer 306, the second layer 306 having a different opacity profile from the first layer 304. In an embodiment, at least a portion of the intra-oral radiation shield structure 302 is formed from at least one x-ray attenuating material, x-ray radio-opaque material, or x-ray attenuating ceramic material. In an embodiment, at least a portion of the intra-oral radiation shield structure 302 is formed from at least one ferromagnetic material, ferrimagnetic material, or paramagnetic material. In an embodiment, at least a portion of the intra-oral radiation shield structure 302 is composed of one or more high-Z, high-density, materials. In an embodiment, at least a portion of the intra-oral radiation shield structure 302 is composed of at least a first x-ray attenuating ceramic material and a second x-ray attenuating ceramic material, the second x-ray attenuating ceramic material having a different x-ray attenuation profile from the first x-ray attenuating ceramic material. In an embodiment, the intra-oral radiation shield structure 302 includes a laminate structure having at least a first layer 304 and a second layer 306, the second layer 306 having a different x-ray attenuation profile from the first layer 304. In an embodiment, at least a portion of the intra-oral radiation shield structure 302 is composed of at least a first x-ray shielding material and a second x-ray shielding material, the second x-ray shielding material having one or more absorption edges different from the first x-ray shielding material. In an embodiment, at least one of the first x-ray shielding material or the second x-ray shielding material includes at least one material that absorbs x-rays at one or more frequencies and fluoresce x-rays at one or more lower frequencies. In an embodiment, at least one absorption edge of the second x-ray shielding material is selected to maximize absorption of x-rays fluoresced by the first x-ray shielding material. In an embodiment, at least a portion of the second x-ray shielding material is mounted between an x-ray image detector and a portion of the first x-ray shielding material on the intra-oral x-ray sensor 102. In an embodiment, at least a portion of the second x-ray shielding material is intermixed with at least a portion of the first x-ray shielding material. In an embodiment, at least a portion of the second x-ray shielding material is interlayered with at least a portion of the first x-ray shielding material. In an embodiment, at least a portion of the intra-oral radiation shield structure 302 is composed of at least a first x-ray shielding material and a second x-ray shielding material, the second x-ray shielding material having a different absorption edge profile from the first x-ray shielding material. In an embodiment, the intra-oral radiation shield structure 302 includes a laminate structure having at least a first layer 304 and a second layer 306, the second layer 306 having a different x-ray absorption edge profile from the first layer 304. In an embodiment, the second x-ray shielding material includes one or more K-edges, or one or more L-edges, different from the first x-ray shielding material. In an embodiment, the second x-ray shielding material includes at least one K-edge having an energy level lower than at least one K-edge of the first x-ray shielding material. In an embodiment, at least one of the first x-ray shielding material or the second x-ray shielding material includes at least one of lead (Pb), tantalum (Ta), or tungsten (W). In an embodiment, the second x-ray shielding material comprises an x-ray mass attenuation coefficient different from the first x-ray shielding material. In an embodiment, the intra-oral radiation shield structure 302 includes one or more x-ray shielding agents. For example, in an embodiment, the intra-oral radiation shield structure 302 includes a composition having a carrier fluid and a plurality of x-ray shielding particles each having at least a first x-ray shielding agent and a second x-ray shielding agent, the second x-ray shielding agent having one or more absorption edges different from the first x-ray shielding agent. In an embodiment, the intra-oral radiation shield structure 302 includes at least a first x-ray shielding agent and a second x-ray shielding agent, the second x-ray shielding agent having one or more absorption edges different from the first x-ray shielding agent. In an embodiment, the intra-oral radiation shield structure 302 includes at least a first x-ray shielding agent and a second x-ray shielding agent. In an embodiment, at least one of the first x-ray shielding agent or the second x-ray shielding agent includes at least one of mercury (Hg), lead (Pb), tantalum (Ta), or tungsten (W). In an embodiment, at least one of the first x-ray shielding agent or the second x-ray shielding agent includes at least one of teflon (C2F4), lead (II) oxide (PbO), or silicon nitride (Si3N4). In an embodiment, at least one of the first x-ray shielding agent or the second x-ray shielding agent includes at least one of boron, molybdenum, neodymium, niobium, strontium, tungsten yttrium, or zirconium, or combinations thereof. In an embodiment, at least one of the first x-ray shielding agent or the second x-ray shielding agent includes at least one of barium sulfate (BaSO4), boron nitride (BN), boron carbide (B4C), boron oxide (B2O3), or barium oxide (BaO). In an embodiment, at least one of the first x-ray shielding agent or the second x-ray shielding agent includes at least one of strontium oxide (SrO), zinc oxide (ZnO), or zirconium dioxide (ZrO2). In an embodiment, at least one of the first x-ray shielding agent or the second x-ray shielding agent includes at least one of SiO2—PbO-alkali metal oxide glass, CaO—SrO—B2O3 glass, or boron-lithium glass. In an embodiment, at least one of the first x-ray shielding agent or the second x-ray shielding agent includes borated high density polyethylene. In an embodiment, at least one of the first x-ray shielding agent or the second x-ray shielding agent includes at least one of mylar (C10H8O4), parylene-C (C8H7Cl), parylene-N(C8H8), poly(methyl methacrylate) (PMMA), polycarbonate (C16H4O3), polyethylene, or ultra-high molecular weight polyethylene. In an embodiment, a portion of the intra-oral radiation shield structure 302 is configured to have an x-ray shielding lead equivalence of about 0.25 millimeters to about 0.5 millimeters. For example, in an embodiment, a portion of the intra-oral radiation shield structure 302 includes a sufficient amount of x-ray shielding materials to have an x-ray shielding lead equivalence of about 0.25 millimeters to about 0.5 millimeters. In an embodiment, x-ray shielding lead equivalence is configured based on an anticipated x-ray spectrum. In an embodiment, a portion of the intra-oral radiation shield structure 302 has an x-ray shielding lead equivalence of greater than about 0.25 millimeters. In an embodiment, a portion of the intra-oral radiation shield structure 302 includes a plurality of x-ray shielding particles. In an embodiment, a portion of the intra-oral radiation shield structure 302 extends outwardly beyond a terminal border of an x-ray image detector forming part of the intra-oral x-ray sensor 102. In an embodiment, the intra-oral radiation shield is structured and dimensioned to conform to a portion of an oral cavity. In an embodiment, a portion of the intra-oral radiation shield structure 302 is flexible or jointed so as to conform to a portion of an oral cavity. Referencing FIG. 3A, in an embodiment, the intra-oral x-ray sensor 102 includes an embedded orientation detection component 316 configured to generate information associated with at least one of an intra-oral x-ray sensor orientation, an intra-oral x-ray sensor position, an intra-oral x-ray sensor dimension, or an intra-oral x-ray sensor centroid position. In an embodiment, the embedded orientation detection component 316 is operably coupled to one or more orientation sensors 318. For example, in an embodiment, the embedded orientation detection component 316 is operably coupled to one or more magnetic compass based sensors. In an embodiment, the embedded orientation detection component 316 is operably coupled to one or more embedded magnetic compass sensors. In an embodiment, the embedded orientation detection component 316 is operably coupled to one or more local positioning system based sensors 320. In an embodiment, the embedded orientation detection component 316 is operably coupled to at least two acceleration sensors 322 in a substantially perpendicularly arrangement. In an embodiment, the embedded orientation detection component 316 is operably coupled to at least one gyroscope 324. In an embodiment, the embedded orientation detection component 316 is operably coupled to at least one electrolytic fluid based sensor 326. In an embodiment, the embedded orientation detection component 316 is operably coupled to at least one transmitter (wired or wireless) configured to report position or orientation information to the remote x-ray source 105. In an embodiment, the embedded orientation detection component 316 is operably coupled to a two-axis tilt sensor 328 configured to detect an intra-oral x-ray sensor pitch angle and an intra-oral x-ray sensor roll angle. In an embodiment, the embedded orientation detection component 316 is operably coupled to at least one multi-axis accelerometer 330. In an embodiment, the embedded orientation detection component 316 is operably coupled to one or more orientation-aware sensors 332. In an embodiment, the embedded orientation detection component 316 is operably coupled to one or more inductors 334. In an embodiment, the embedded orientation detection component 316 is operably coupled to one or more acoustic transducers 336. In an embodiment, the x-ray image component 116 is operably coupled to one or more dental digital x-ray sensors. In an embodiment, the x-ray image component 116 is operably coupled to one or more dental digital x-ray sensors. In an embodiment, the x-ray image component 116 is operably coupled to one or more charge-coupled devices 338. In an embodiment, the x-ray image component 116 is operably coupled to one or more active pixel image sensors 340. In an embodiment, the x-ray image component 116 is operably coupled to one or more complementary metal-oxide-semiconductor sensors 342. In an embodiment, the x-ray image component 116 is operably coupled to one or more complementary metal-oxide-semiconductor active pixel sensors 344. In an embodiment, the intra-oral x-ray sensor 102 includes one or more passive optics devices 204 configured to indicate an intra-oral x-ray sensor border position. In an embodiment, the intra-oral x-ray sensor 102 includes one or more active optic devices 228 (e.g., beacons, acoustic emitters, optical emitters, etc.) configured to generate an output indicative of an intra-oral x-ray sensor border position. In an embodiment, the intra-oral x-ray sensor 102 includes a beacon component 346 configured to convey information associated with at least one of a sensor position or a sensor orientation. In an embodiment, the beacon component 346 is operably coupled to a transducer configured to generate an output indicative of an intra-oral x-ray sensor border position. In an embodiment, the beacon component 346 is operably coupled to one or more transducers configured to generate an output indicative of an intra-oral x-ray sensor border position. In an embodiment, the beacon component 346 is operably coupled to one or more active optic devices configured to generate an output indicative of an intra-oral x-ray sensor border position. In an embodiment, the beacon component 346 is operably coupled to one or more inductors configured to generate an output indicative of an intra-oral x-ray sensor border position. In an embodiment, the beacon component 346 is operably coupled to one or more accelerometers configured to generate an output indicative of an intra-oral x-ray sensor orientation. In an embodiment, the beacon component 346 is operably coupled to one or more gyroscopes configured to generate an output indicative of an intra-oral x-ray sensor orientation. In an embodiment, the beacon component 346 is operably coupled to one or more electrolytic fluid based sensors 326 configured to generate an output indicative of an intra-oral x-ray sensor orientation. In an embodiment, the intra-oral x-ray sensor 102 includes an x-ray backscatter component 348 operably coupled to the x-ray image component 116. In an embodiment, the x-ray backscatter component 348 is configured to modify the intra-oral x-ray image information responsive to one or more inputs from the x-ray image component 116 indicative of backscatter, i.e., to computationally remove image noise resulting from backscattered x-rays. In an embodiment, the intra-oral x-ray sensor 102 includes circuitry 352 configured to communicate intra-oral x-ray sensor position information to a remote x-ray source 105. In an embodiment, communication with the remote x-ray source 105 can be wired or wirelessly connected to the intra-oral x-ray sensor 102. In an embodiment, the circuitry 352 configured to communicate the intra-oral sensor 102 position to the remote x-ray source 105 comprises one or more of a receiver, transmitter, or transceiver. In an embodiment, the circuitry 352 configured to communicate the intra-oral sensor 102 position to the remote x-ray source 105 comprises a wireless transmitter. In an embodiment, the circuitry 352 configured to communicate the intra-oral sensor 102 position is operably coupled to one or more radiation reflecting elements (e.g., prisms retro-reflectors, etc.). In an embodiment, the circuitry 352 configured to communicate the intra-oral sensor 102 position is operably coupled to a modulatable reflector. In an embodiment, the intra-oral x-ray sensor 102 includes circuitry 354 configured to verify an x-ray beam characteristic associated with the remote x-ray source 105. In an embodiment, the circuitry 354 configured to verify the x-ray beam characteristic associated with the remote x-ray source 105 includes circuitry configured to determine x-ray beam centroid information associated with the remote x-ray source 105. In an embodiment, the circuitry 354 configured to verify the x-ray beam characteristic associated with the remote x-ray source 105 includes circuitry configured to determine a spatial pattern associated with an x-ray beam received from the remote x-ray source 105. In an embodiment, the circuitry 354 configured to verify the x-ray beam characteristic associated with the remote x-ray source 105 includes circuitry configured to determine a spatial alignment associated with an x-ray beam received from the remote x-ray source 105. In an embodiment, the circuitry 354 configured to verify the x-ray beam characteristic associated with the remote x-ray source 105 includes circuitry configured to determine lateral overlap information associated with an x-ray beam received from the remote x-ray source 105 and an intra-oral x-ray sensor 102. In an embodiment, the intra-oral x-ray sensor 102 includes circuitry 356 configured to communicate an x-ray beam field of view parameter to the remote x-ray source 105 responsive to verifying an x-ray beam characteristic. In an embodiment, the circuitry 356 configured to communicate the x-ray beam field of view parameter to the remote x-ray source 105 comprises one or more of a receiver, transmitter, or transceiver. In an embodiment, the circuitry 356 configured to communicate the x-ray beam field of view parameter to the remote x-ray source 105 comprises a wireless transmitter. In an embodiment, the intra-oral x-ray sensor 102 includes circuitry 358 configured to generate intra-oral x-ray sensor orientation information. In an embodiment, the circuitry 358 configured to generate intra-oral x-ray sensor orientation information is operably coupled to one or more embedded magnetic compasses. In an embodiment, the circuitry 358 configured to generate the intra-oral x-ray sensor orientation information is operably coupled to one or more electrolytic fluid based sensors 222. In an embodiment, the circuitry 358 configured to generate the intra-oral x-ray sensor orientation information is operably coupled to one or more acceleration sensors. In an embodiment, the circuitry 358 configured to generate the intra-oral x-ray sensor orientation information is operably coupled to one or more multi-axis accelerometers 330. In an embodiment, the circuitry 358 configured to generate the intra-oral x-ray sensor orientation information is operably coupled to at least two acceleration sensors in a substantially perpendicularly arrangement. In an embodiment, the circuitry 358 configured to generate the intra-oral x-ray sensor orientation information is operably coupled to one or more orientation-aware sensors 332. In an embodiment, the intra-oral x-ray sensor 102 includes circuitry 360 configured to generate intra-oral x-ray sensor position information. In an embodiment, the circuitry 360 configured to generate the intra-oral x-ray sensor position information is operably coupled to one or more local positioning system based sensors. In an embodiment, the circuitry 360 configured to generate the intra-oral x-ray sensor position information is operably coupled to one or more inductors 334. In an embodiment, the circuitry 360 configured to generate the intra-oral x-ray sensor position information is operably coupled to one or more active optic devices (e.g., photodetectors, imagers, CCD detectors, CMOS detectors, etc.). In an embodiment, the circuitry 360 configured to generate the intra-oral x-ray sensor position information is operably coupled to one or more acoustic transducers 336 configured to generate an output indicative of an intra-oral x-ray sensor border position and an intra-oral x-ray sensor orientation. In an embodiment, the circuitry 360 configured to generate the intra-oral x-ray sensor position information is operably coupled to one or more border indicating beacon devices 118. In an embodiment, the intra-oral x-ray sensor 102 includes circuitry 362 configured to determine remote x-ray source 105 and intra-oral x-ray sensor alignment before communicating an activation instruction to the remote x-ray source 105 for imaging. In an embodiment, the intra-oral x-ray sensor 102 includes circuitry 364 configured to acquire a low intensity x-ray pulse to determine remote x-ray source 105 and intra-oral x-ray sensor alignment before communicating an activation instruction to the remote x-ray source 105 for imaging. In an embodiment, the intra-oral x-ray sensor 102 includes an integrated component including one or more of the circuitry 352 configured to communicate the intra-oral sensor 102 position is operably coupled to a modulatable reflector; the circuitry 354 configured to verify an x-ray beam characteristic associated with the remote x-ray source 105; the circuitry 356 configured to communicate an x-ray beam field of view parameter to the remote x-ray source 105 responsive to verifying an x-ray beam characteristic; the circuitry 358 configured to generate intra-oral x-ray sensor orientation information; the circuitry 360 configured to generate intra-oral x-ray sensor position information; the circuitry 362 configured to determine remote x-ray source 105; the circuitry 364 configured to acquire a low intensity x-ray pulse to determine remote x-ray source 105 and intra-oral x-ray sensor alignment before communicating an activation instruction to the remote x-ray source 105 for imaging; or the like. FIGS. 4A-4C show an intra-oral x-ray imaging method 400. At 410, the intra-oral x-ray imaging method 400 includes automatically determining an intra-oral x-ray sensor border position and an intra-oral x-ray sensor orientation. At 412, automatically determining the intra-oral x-ray sensor border position and the intra-oral x-ray sensor orientation includes wirelessly detecting an intra-oral x-ray sensor beacon output indicative of the intra-oral x-ray sensor border position and the intra-oral x-ray sensor orientation. At 414, automatically determining the intra-oral x-ray sensor border position and the intra-oral x-ray sensor orientation includes detecting at least one passive reflector associated with an intra-oral x-ray sensor and generating intra-oral x-ray sensor border position information and intra-oral x-ray sensor orientation information. At 416, automatically determining the intra-oral x-ray sensor border position and the intra-oral x-ray sensor orientation includes detecting a transducer response associated with an intra-oral x-ray sensor 102 and generating intra-oral x-ray sensor border position information and intra-oral x-ray sensor orientation information. At 418, automatically determining the intra-oral x-ray sensor border position and the intra-oral x-ray sensor orientation includes detecting a reference component associated with an intra-oral x-ray sensor 102 and generating intra-oral x-ray sensor border position information responsive to detecting the reference component. At 420, automatically determining the intra-oral x-ray sensor border position and the intra-oral x-ray sensor orientation includes detecting a reference component associated with an intra-oral x-ray sensor 102 and generating intra-oral x-ray sensor orientation information responsive to detecting the reference component. At 422, automatically determining the intra-oral x-ray sensor border position and the intra-oral x-ray sensor orientation includes acquiring at least one parameter from an accelerometer associated with an intra-oral x-ray sensor 102 and generating the intra-oral x-ray sensor orientation responsive to acquiring the at least one parameter from the accelerometer. At 430, the intra-oral x-ray imaging method 400 includes varying an x-ray beam field of view parameter responsive to one or more inputs including information associated with a location of the intra-oral x-ray sensor border position and the intra-oral x-ray sensor orientation. At 432, varying the x-ray beam field of view parameter responsive to one or more inputs including information associated with an intra-oral x-ray sensor border position and an intra-oral x-ray sensor orientation includes varying the collimation size or the collimation shape of an external x-ray source 105 operably coupled to the intra-oral x-ray sensor 102. At 434, varying the x-ray beam field of view parameter responsive to one or more inputs including information associated with the intra-oral x-ray sensor border position and the intra-oral x-ray sensor orientation includes varying the x-ray beam field of view parameter sufficient to minimize overfilling of the intra-oral x-ray sensor 102. At 436, varying the x-ray beam field of view parameter responsive to one or more inputs including information associated with the intra-oral x-ray sensor border position and the intra-oral x-ray sensor orientation includes varying the x-ray beam field of view parameter sufficient to minimize underfilling of the intra-oral x-ray sensor 102. At 438, varying the x-ray beam field of view parameter responsive to one or more inputs including information associated with the intra-oral x-ray sensor border position and the intra-oral x-ray sensor orientation includes varying one or more parameters associated with a field of view setting responsive to automatically determining the intra-oral x-ray sensor border position and the intra-oral x-ray sensor orientation. At 440, varying the x-ray beam field of view parameter responsive to one or more inputs including information associated with the intra-oral x-ray sensor border position and the intra-oral x-ray sensor orientation includes varying a shutter aperture setting. At 442, varying the x-ray beam field of view parameter responsive to one or more inputs including information associated with the intra-oral x-ray sensor border position and the intra-oral x-ray sensor orientation includes varying a diaphragm aperture setting. At 444, varying the x-ray beam field of view parameter responsive to one or more inputs including information associated with the intra-oral x-ray sensor border position and the intra-oral x-ray sensor orientation includes varying a separation between a collimator aperture and an x-ray beam emitter within x-ray source 105. At 446, varying the x-ray beam field of view parameter responsive to one or more inputs including information associated with the intra-oral x-ray sensor border position and the intra-oral x-ray sensor orientation includes varying an orientation between a collimator aperture and an x-ray beam emitter within x-ray source 105. At 448, varying the x-ray beam field of view parameter responsive to one or more inputs including information associated with the intra-oral x-ray sensor border position and the intra-oral x-ray sensor orientation includes actuating one or more selectively actuatable absorber blades forming part of a focal plane shutter. At 450, varying the x-ray beam field of view parameter responsive to one or more inputs including information associated with the intra-oral x-ray sensor border position and the intra-oral x-ray sensor orientation includes actuating an x-ray beam limiter assembly 108 configured to adjust an x-ray beam field size. At 452, varying the x-ray beam field of view parameter responsive to one or more inputs including information associated with the intra-oral x-ray sensor border position and the intra-oral x-ray sensor orientation includes generating one or more parameters associated with an x-ray beam field size adjustment responsive to automatically determining the intra-oral x-ray sensor border position and the intra-oral x-ray sensor orientation. At 454, varying the x-ray beam field of view parameter responsive to one or more inputs including information associated with the intra-oral x-ray sensor border position and the intra-oral x-ray sensor orientation includes generating one or more x-ray beam limiter assembly 108 setting parameters responsive to automatically determining the intra-oral x-ray sensor border position and the intra-oral x-ray sensor orientation. At 456, varying the x-ray beam field of view parameter responsive to one or more inputs including information associated with the intra-oral x-ray sensor border position and the intra-oral x-ray sensor orientation includes actuating at least one liquid absorber. At 460, the intra-oral x-ray imaging method 400 includes acquiring intra-oral x-ray image information associated with a patient. At 462, acquiring the intra-oral x-ray image information associated with the patient includes acquiring one or more intra-oral radiographic images. At 464, acquiring the intra-oral x-ray image information associated with the patient includes acquiring intra-oral radiographic view information. At 466, acquiring the intra-oral x-ray image information associated with the patient includes acquiring a periapical view image of at least one anterior or posterior tooth. At 468, acquiring the intra-oral x-ray image information associated with the patient includes acquiring a bitewing view image of at least one tooth crown. At 470, acquiring the intra-oral x-ray image information associated with the patient includes acquiring an occlusal view image of a palate. At 472, acquiring the intra-oral x-ray image information associated with the patient includes acquiring a posterior periapical image. At 474, acquiring the intra-oral x-ray image information associated with the patient includes acquiring an anterior periapical image. At 478, the intra-oral x-ray imaging method 400 includes generating at least one parameter associated with an x-ray imaging mode (e.g., adult panoramic mode, child panoramic mode, high-dose-rate mode, low-dose-rate mode, moderate-dose-rate mode mandible mode, occlusion mode, maxillary mode, panoramic mode, pulsed fluoroscopy mode, temporomandibular joint mode, etc.) responsive to automatically determining the intra-oral x-ray sensor border position and the intra-oral x-ray sensor orientation. At 480, the intra-oral x-ray imaging method 400 includes varying an x-ray beam aim parameter responsive to automatically determining the intra-oral x-ray sensor border position and the intra-oral x-ray sensor orientation. At 490, the intra-oral x-ray imaging method 400 includes communicating intra-oral x-ray sensor position information to a remote x-ray source 105. At 492, communicating the intra-oral x-ray sensor position information to the remote x-ray source 105 includes communicating intra-oral x-ray sensor dimension information to the remote x-ray source 105. At 494, communicating the intra-oral x-ray sensor position information to the remote x-ray source 105 includes communicating intra-oral x-ray sensor orientation information to the remote x-ray source 105. At 496, communicating the intra-oral x-ray sensor position information to the remote x-ray source 105 includes communicating one or more outputs indicative of an intra-oral x-ray sensor border position. At 498, the intra-oral x-ray imaging method 400 includes communicating intra-oral x-ray sensor orientation information to a remote x-ray source 105. FIG. 5 shows an intra-oral x-ray sensor operation method 500. At 510, the intra-oral x-ray sensor operation method 500 includes verifying an x-ray beam characteristic associated with the remote x-ray source 105. At 520, the intra-oral x-ray sensor operation method 500 includes communicating an x-ray beam field of view parameter to the remote x-ray source 105 responsive to verifying an x-ray beam characteristic. At 522, communicating the x-ray beam field of view parameter to the remote x-ray source 105 includes communicating a parameter associated with a change in separation between a collimator aperture 114 and the remote x-ray source 105. At 524, communicating the x-ray beam field of view parameter to the remote x-ray source 105 includes communicating a parameter associated with actuating one or more electro-mechanical collimation edges. At 526, communicating the x-ray beam field of view parameter to the remote x-ray source 105 includes communicating a parameter associated with displacing, moving, or rotating one or more collimation edges. At 528 communicating the x-ray beam field of view parameter to the remote x-ray source 105 includes communicating a parameter associated with adjusting a relative position of an x-ray beam emitter within the remote x-ray source 105 and a collimator 110 to improve alignment of the x-ray beam to the sensor. At 530, the intra-oral x-ray sensor operation method 500 includes activating a discovery protocol that allows an intra-oral x-ray sensor 102 and the remote x-ray source 105 to identify each other and to negotiate information. At 540, the intra-oral x-ray sensor operation method 500 includes determining a remote x-ray source 105 and intra-oral x-ray sensor alignment. At 550, the intra-oral x-ray sensor operation method 500 includes communicating an activation instruction to the remote x-ray source 105 for imaging responsive to determining the remote x-ray source 105 and intra-oral x-ray sensor 102 alignment. At 560, the intra-oral x-ray sensor operation method 500 includes detecting a low intensity x-ray pulse to determine remote x-ray source 105 and intra-oral x-ray sensor alignment. At 570, the intra-oral x-ray sensor operation method 500 includes communicating an activation instruction to the remote x-ray source 105 for imaging responsive to detecting the low intensity x-ray pre-pulse to determine remote the x-ray source 105 and intra-oral x-ray sensor 102 alignment. It is noted that FIGS. 4A-4C and 5 denotes “start” and “end” positions. However, nothing herein should be construed to indicate that these are limiting and it is contemplated that other or additional steps or functions can occur before or after those described in FIGS. 4A-4C and 5. The claims, description, and drawings of this application may describe one or more of the instant technologies in operational/functional language, for example as a set of operations to be performed by a computer. Such operational/functional description in most instances can be specifically-configured hardware (e.g., because a general purpose computer in effect becomes a special purpose computer once it is programmed to perform particular functions pursuant to instructions from program software). Importantly, although the operational/functional descriptions described herein are understandable by the human mind, they are not abstract ideas of the operations/functions divorced from computational implementation of those operations/functions. Rather, the operations/functions represent a specification for the massively complex computational machines or other means. As discussed in detail below, the operational/functional language must be read in its proper technological context, i.e., as concrete specifications for physical implementations. The logical operations/functions described herein are a distillation of machine specifications or other physical mechanisms specified by the operations/functions such that the otherwise inscrutable machine specifications may be comprehensible to the human mind. The distillation also allows one of skill in the art to adapt the operational/functional description of the technology across many different specific vendors' hardware configurations or platforms, without being limited to specific vendors' hardware configurations or platforms. Some of the present technical description (e.g., detailed description, drawings, claims, etc.) may be set forth in terms of logical operations/functions. As described in more detail in the following paragraphs, these logical operations/functions are not representations of abstract ideas, but rather representative of static or sequenced specifications of various hardware elements. Differently stated, unless context dictates otherwise, the logical operations/functions are representative of static or sequenced specifications of various hardware elements. This is true because tools available to implement technical disclosures set forth in operational/functional formats—tools in the form of a high-level programming language (e.g., C, java, visual basic), etc.), or tools in the form of Very high speed Hardware Description Language (“VIDAL,” which is a language that uses text to describe logic circuits—)—are generators of static or sequenced specifications of various hardware configurations. This fact is sometimes obscured by the broad term “software,” but, as shown by the following explanation, what is termed “software” is a shorthand for a massively complex interchanging/specification of ordered-matter elements. The term “ordered-matter elements” may refer to physical components of computation, such as assemblies of electronic logic gates, molecular computing logic constituents, quantum computing mechanisms, etc. For example, a high-level programming language is a programming language with strong abstraction, e.g., multiple levels of abstraction, from the details of the sequential organizations, states, inputs, outputs, etc., of the machines that a high-level programming language actually specifies. See, e.g., High-level Programming Language., Wikipedia. Wikimedia Foundation, 18 Jan. 2014. Web. 4 Feb. 2014. In order to facilitate human comprehension, in many instances, high-level programming languages resemble or even share symbols with natural languages. See, e.g., Natural Language., Wikipedia. Wikimedia Foundation, 14 Jan. 2014. Web. 4 Feb. 2014. It has been argued that because high-level programming languages use strong abstraction (e.g., that they may resemble or share symbols with natural languages), they are therefore a “purely mental construct” (e.g., that “software”—a computer program or computer—programming—is somehow an ineffable mental construct, because at a high level of abstraction, it can be conceived and understood in the human mind). This argument has been used to characterize technical description in the form of functions/operations as somehow “abstract ideas.” In fact, in technological arts (e.g., the information and communication technologies) this is not true. The fact that high-level programming languages use strong abstraction to facilitate human understanding should not be taken as an indication that what is expressed is an abstract idea. In an embodiment, if a high-level programming language is the tool used to implement a technical disclosure in the form of functions/operations, it can be understood that, far from being abstract, imprecise, “fuzzy,” or “mental” in any significant semantic sense, such a tool is instead a near incomprehensibly precise sequential specification of specific computational—machines—the parts of which are built up by activating/selecting such parts from typically more general computational machines over time (e.g., clocked time). This fact is sometimes obscured by the superficial similarities between high-level programming languages and natural languages. These superficial similarities also may cause a glossing over of the fact that high-level programming language implementations ultimately perform valuable work by creating/controlling many different computational machines. The many different computational machines that a high-level programming language specifies are almost unimaginably complex. At base, the hardware used in the computational machines typically consists of some type of ordered matter (e.g., traditional electronic devices (e.g., transistors), deoxyribonucleic acid (DNA), quantum devices, mechanical switches, optics, fluidics, pneumatics, optical devices (e.g., optical interference devices), molecules, etc.) that are arranged to form logic gates. Logic gates are typically physical devices that may be electrically, mechanically, chemically, or otherwise driven to change physical state in order to create a physical reality of Boolean logic. Logic gates may be arranged to form logic circuits, which are typically physical devices that may be electrically, mechanically, chemically, or otherwise driven to create a physical reality of certain logical functions. Types of logic circuits include such devices as multiplexers, registers, arithmetic logic units (ALUs), computer memory devices, etc., each type of which may be combined to form yet other types of physical devices, such as a central processing unit (CPU)—the best known of which is the microprocessor. A modern microprocessor will often contain more than one hundred million logic gates in its many logic circuits (and often more than a billion transistors). See, e.g., Logic Gates., Wikipedia. Wikimedia Foundation, 2 Apr. 2014. Web. 4 Feb. 2014. The logic circuits forming the microprocessor are arranged to provide a microarchitecture that will carry out the instructions defined by that microprocessor's defined Instruction Set Architecture. The Instruction Set Architecture is the part of the microprocessor architecture related to programming, including the native data types, instructions, registers, addressing modes, memory architecture, interrupt and exception handling, and external Input/Output. See, e.g., Computer Architecture., Wikipedia. Wikimedia Foundation, 2 Feb. 2014. Web. 4 Feb. 2014. The Instruction Set Architecture includes a specification of the machine language that can be used by programmers to use/control the microprocessor. Since the machine language instructions are such that they may be executed directly by the microprocessor, typically they consist of strings of binary digits, or bits. For example, a typical machine language instruction might be many bits long (e.g., 32, 64, or 128 bit strings are currently common). A typical machine language instruction might take the form “11110000101011110000111100111111” (a 32 bit instruction). It is significant here that, although the machine language instructions are written as sequences of binary digits, in actuality those binary digits specify physical reality. For example, if certain semiconductors are used to make the operations of Boolean logic a physical reality, the apparently mathematical bits “1” and “0” in a machine language instruction actually constitute a shorthand that specifies the application of specific voltages to specific wires. For example, in some semiconductor technologies, the binary number “1” (e.g., logical “1”) in a machine language instruction specifies around +5 volts applied to a specific “wire” (e.g., metallic traces on a printed circuit board) and the binary number “0” (e.g., logical “0”) in a machine language instruction specifies around −5 volts applied to a specific “wire.” In addition to specifying voltages of the machines' configuration, such machine language instructions also select out and activate specific groupings of logic gates from the millions of logic gates of the more general machine. Thus, far from abstract mathematical expressions, machine language instruction programs, even though written as a string of zeros and ones, specify many, many constructed physical machines or physical machine states. Machine language is typically incomprehensible by most humans (e.g., the above example was just ONE instruction, and some personal computers execute more than two billion instructions every second). See, e.g., Instructions per Second., Wikipedia. Wikimedia Foundation, 13 Jan. 2014. Web. 4 Feb. 2014. Thus, programs written in machine language—which may be tens of millions of machine language instructions long—are incomprehensible. In view of this, early assembly languages were developed that used mnemonic codes to refer to machine language instructions, rather than using the machine language instructions' numeric values directly (e.g., for performing a multiplication operation, programmers coded the abbreviation “mult,” which represents the binary number “011000” in MIPS machine code). While assembly languages were initially a great aid to humans controlling the microprocessors to perform work, in time the complexity of the work that needed to be done by the humans outstripped the ability of humans to control the microprocessors using merely assembly languages. At this point, it was noted that the same tasks needed to be done over and over, and the machine language necessary to do those repetitive tasks was the same. In view of this, compilers were created. A compiler is a device that takes a statement that is more comprehensible to a human than either machine or assembly language, such as “add 2+2 and output the result,” and translates that human understandable statement into a complicated, tedious, and immense machine language code (e.g., millions of 32, 64, or 128 bit length strings). Compilers thus translate high-level programming language into machine language. This compiled machine language, as described above, is then used as the technical specification which sequentially constructs and causes the interoperation of many different computational machines such that humanly useful, tangible, and concrete work is done. For example, as indicated above, such machine language—the compiled version of the higher-level language—functions as a technical specification which selects out hardware logic gates, specifies voltage levels, voltage transition timings, etc., such that the humanly useful work is accomplished by the hardware. Thus, a functional/operational technical description, when viewed by one of skill in the art, is far from an abstract idea. Rather, such a functional/operational technical description, when understood through the tools available in the art such as those just described, is instead understood to be a humanly understandable representation of a hardware specification, the complexity and specificity of which far exceeds the comprehension of most any one human. Accordingly, any such operational/functional technical descriptions may be understood as operations made into physical reality by (a) one or more interchained physical machines, (b) interchained logic gates configured to create one or more physical machine(s) representative of sequential/combinatorial logic(s), (c) interchained ordered matter making up logic gates (e.g., interchained electronic devices (e.g., transistors), DNA, quantum devices, mechanical switches, optics, fluidics, pneumatics, molecules, etc.) that create physical reality representative of logic(s), or (d) virtually any combination of the foregoing. Indeed, any physical object which has a stable, measurable, and changeable state may be used to construct a machine based on the above technical description. Charles Babbage, for example, constructed the first computer out of wood and powered by cranking a handle. Thus, far from being understood as an abstract idea, it can be recognizes that a functional/operational technical description as a humanly-understandable representation of one or more almost unimaginably complex and time sequenced hardware instantiations. The fact that functional/operational technical descriptions might lend themselves readily to high-level computing languages (or high-level block diagrams for that matter) that share some words, structures, phrases, etc. with natural language simply cannot be taken as an indication that such functional/operational technical descriptions are abstract ideas, or mere expressions of abstract ideas. In fact, as outlined herein, in the technological arts this is simply not true. When viewed through the tools available to those of skill in the art, such functional/operational technical descriptions are seen as specifying hardware configurations of almost unimaginable complexity. As outlined above, the reason for the use of functional/operational technical descriptions is at least twofold. First, the use of functional/operational technical descriptions allows near-infinitely complex machines and machine operations arising from interchained hardware elements to be described in a manner that the human mind can process (e.g., by mimicking natural language and logical narrative flow). Second, the use of functional/operational technical descriptions assists the person of skill in the art in understanding the described subject matter by providing a description that is more or less independent of any specific vendor's piece(s) of hardware. The use of functional/operational technical descriptions assists the person of skill in the art in understanding the described subject matter since, as is evident from the above discussion, one could easily, although not quickly, transcribe the technical descriptions set forth in this document as trillions of ones and zeroes, billions of single lines of assembly-level machine code, millions of logic gates, thousands of gate arrays, or any number of intermediate levels of abstractions. However, if any such low-level technical descriptions were to replace the present technical description, a person of skill in the art could encounter undue difficulty in implementing the disclosure, because such a low-level technical description would likely add complexity without a corresponding benefit (e.g., by describing the subject matter utilizing the conventions of one or more vendor-specific pieces of hardware). Thus, the use of functional/operational technical descriptions assists those of skill in the art by separating the technical descriptions from the conventions of any vendor-specific piece of hardware. In view of the foregoing, the logical operations/functions set forth in the present technical description are representative of static or sequenced specifications of various ordered-matter elements, in order that such specifications may be comprehensible to the human mind and adaptable to create many various hardware configurations. The logical operations/functions disclosed herein should be treated as such, and should not be disparagingly characterized as abstract ideas merely because the specifications they represent are presented in a manner that one of skill in the art can readily understand and apply in a manner independent of a specific vendor's hardware implementation. At least a portion of the devices or processes described herein can be integrated into an information processing system. An information processing system generally includes one or more of a system unit housing, a video display device, memory, such as volatile or non-volatile memory, processors such as microprocessors or digital signal processors, computational entities such as operating systems, drivers, graphical user interfaces, and applications programs, one or more interaction devices (e.g., a touch pad, a touch screen, an antenna, etc.), or control systems including feedback loops and control motors (e.g., feedback for detecting position or velocity, control motors for moving or adjusting components or quantities). An information processing system can be implemented utilizing suitable commercially available components, such as those typically found in data computing/communication or network computing/communication systems. The state of the art has progressed to the point where there is little distinction left between hardware and software implementations of aspects of systems; the use of hardware or software is generally (but not always, in that in certain contexts the choice between hardware and software can become significant) a design choice representing cost vs. efficiency tradeoffs. Various vehicles by which processes or systems or other technologies described herein can be effected (e.g., hardware, software, firmware, etc., in one or more machines or articles of manufacture), and that the preferred vehicle will vary with the context in which the processes, systems, other technologies, etc., are deployed. For example, if an implementer determines that speed and accuracy are paramount, the implementer may opt for a mainly hardware or firmware vehicle; alternatively, if flexibility is paramount, the implementer may opt for a mainly software implementation that is implemented in one or more machines or articles of manufacture; or, yet again alternatively, the implementer may opt for some combination of hardware, software, firmware, etc. in one or more machines or articles of manufacture. Hence, there are several possible vehicles by which the processes, devices, other technologies, etc., described herein may be effected, none of which is inherently superior to the other in that any vehicle to be utilized is a choice dependent upon the context in which the vehicle will be deployed and the specific concerns (e.g., speed, flexibility, or predictability) of the implementer, any of which may vary. In an embodiment, optical aspects of implementations will typically employ optically-oriented hardware, software, firmware, etc., in one or more machines or articles of manufacture. The herein described subject matter sometimes illustrates different components contained within, or connected with, different other components. It is to be understood that such depicted architectures are merely examples, and that in fact, many other architectures can be implemented that achieve the same functionality. In a conceptual sense, any arrangement of components to achieve the same functionality is effectively “associated” such that the desired functionality is achieved. Hence, any two components herein combined to achieve a particular functionality can be seen as “associated with” each other such that the desired functionality is achieved, irrespective of architectures or intermedial components. Likewise, any two components so associated can also be viewed as being “operably connected”, or “operably coupled,” to each other to achieve the desired functionality, and any two components capable of being so associated can also be viewed as being “operably coupleable,” to each other to achieve the desired functionality. Specific examples of operably coupleable include, but are not limited to, physically mateable, physically interacting components, wirelessly interactable, wirelessly interacting components, logically interacting, logically interactable components, etc. In an embodiment, one or more components may be referred to herein as “configured to,” “configurable to,” “operable/operative to,” “adapted/adaptable,” “able to,” “conformable/conformed to,” etc. Such terms (e.g., “configured to”) can generally encompass active-state components, or inactive-state components, or standby-state components, unless context requires otherwise. The foregoing detailed description has set forth various embodiments of the devices or processes via the use of block diagrams, flowcharts, or examples. Insofar as such block diagrams, flowcharts, or examples contain one or more functions or operations, it will be understood by the reader that each function or operation within such block diagrams, flowcharts, or examples can be implemented, individually or collectively, by a wide range of hardware, software, firmware in one or more machines or articles of manufacture, or virtually any combination thereof. Further, the use of “Start,” “End,” or “Stop” blocks in the block diagrams is not intended to indicate a limitation on the beginning or end of any functions in the diagram. Such flowcharts or diagrams may be incorporated into other flowcharts or diagrams where additional functions are performed before or after the functions shown in the diagrams of this application. In an embodiment, several portions of the subject matter described herein is implemented via Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), digital signal processors (DSPs), or other integrated formats. However, some aspects of the embodiments disclosed herein, in whole or in part, can be equivalently implemented in integrated circuits, as one or more computer programs running on one or more computers (e.g., as one or more programs running on one or more computer systems), as one or more programs running on one or more processors (e.g., as one or more programs running on one or more microprocessors), as firmware, or as virtually any combination thereof, and that designing the circuitry or writing the code for the software and or firmware would be well within the skill of one of skill in the art in light of this disclosure. In addition, the mechanisms of the subject matter described herein are capable of being distributed as a program product in a variety of forms, and that an illustrative embodiment of the subject matter described herein applies regardless of the particular type of signal-bearing medium used to actually carry out the distribution. Non-limiting examples of a signal-bearing medium include the following: a recordable type medium such as a floppy disk, a hard disk drive, a Compact Disc (CD), a Digital Video Disk (DVD), a digital tape, a computer memory, etc.; and a transmission type medium such as a digital or an analog communication medium (e.g., a fiber optic cable, a waveguide, a wired communications link, a wireless communication link (e.g., transmitter, receiver, transmission logic, reception logic, etc.), etc.). While particular aspects of the present subject matter described herein have been shown and described, it will be apparent to the reader that, based upon the teachings herein, changes and modifications can be made without departing from the subject matter described herein and its broader aspects and, therefore, the appended claims are to encompass within their scope all such changes and modifications as are within the true spirit and scope of the subject matter described herein. In general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). Further, if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to claims containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense of the convention (e.g., “a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense of the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). Typically a disjunctive word or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms unless context dictates otherwise. For example, the phrase “A or B” will be typically understood to include the possibilities of “A” or “B” or “A and B.” With respect to the appended claims, the operations recited therein generally may be performed in any order. Also, although various operational flows are presented in a sequence(s), it should be understood that the various operations may be performed in orders other than those that are illustrated, or may be performed concurrently. Examples of such alternate orderings includes overlapping, interleaved, interrupted, reordered, incremental, preparatory, supplemental, simultaneous, reverse, or other variant orderings, unless context dictates otherwise. Furthermore, terms like “responsive to,” “related to,” or other past-tense adjectives are generally not intended to exclude such variants, unless context dictates otherwise. While various aspects and embodiments have been disclosed herein, other aspects and embodiments are contemplated. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.
	abstract	A method that purposely relaxes OPC algorithm constraints to allow post OPC mask shapes to elongate along one direction (particularly lowering the 1-dimensional MEEF in this direction with the result of an effectively overall lowered MEEF) to produce a pattern on wafer that is circular to within an acceptable tolerance.
	claims	1. A lithographic projection apparatus, comprising:an illumination system configured to form a beam of radiation from radiation provided by an EUV radiation source;a support configured to hold a patterning device which is to be irradiated by the beam to pattern the beam;a substrate table configured to hold a substrate;a projection system configured to image an irradiated portion of the patterning device onto a target portion of the substrate;a reflector assembly placed in the vicinity of the source or an image of the EUV radiation source, the reflector assembly comprising at least an inner and an outer reflector extending in a direction of an optical axis on which the EUV radiation source or an image of the EUV radiation source is located, the inner reflector being closer to the optical axis than the outer reflector, the inner and outer reflectors each having an inner reflective surface and an outer backing layer, the inner reflective surface of the outer reflector facing the backing layer of the inner reflector;a foil trap configured to collect debris from the EUV radiation source, the foil trap being between the EUV radiation source and the reflector assembly;a housing constructed and arranged to contain the reflector assembly and the foil trap, the reflector assembly being connected to the housing via a first wall, and the foil trap being connected to the housing via a second wall;a chamber between the foil trap and the reflector assembly, the chamber being defined by the housing, the first wall, and the second wall; anda pump configured to create a vacuum in the chamber. 2. A lithographic projection apparatus according to claim 1, the housing constructed and arranged to contain the EUV radiation source. 3. A lithographic projection apparatus according to claim 1, further comprising a second pump configured to evacuate a space in the housing behind the reflector assembly. 4. A lithographic projection apparatus according to claim 1, wherein the outer backing layer of the inner reflectors is covered with a reflective layer having a reflectivity of between 0.7 and 0.99 for wavelengths between 0.1 and 100 μm. 5. A lithographic projection apparatus according to claim 1, wherein the outer backing layer of the outer reflector is covered with a radiative layer having a emissivity of between 0.6 and 0.95 for wavelengths between 0.1 and 100 μm. 6. A lithographic projection apparatus according to claim 5, wherein the radiative layer comprises carbon. 7. A lithographic projection apparatus according to claim 1, wherein the inner reflective layer comprises a noble metal. 8. A lithographic projection apparatus according to claim 7, wherein the noble metal comprises gold or ruthenium. 9. A lithographic projection apparatus according to claim 1, wherein the inner and outer reflectors are substantially coaxial and extend substantially rotationally symmetric around the optical axis. 10. A lithographic projection apparatus according to claim 1 wherein at least the outer reflector comprises radiation fins. 11. An assembly for collecting EUV radiation from an EUV radiation source, the assembly comprising:a reflector assembly placed in the vicinity of the source or an image of the EUV radiation source, the reflector assembly comprising at least an inner and an outer reflector extending in a direction of an optical axis on which the EUV radiation source or an image of the EUV radiation source is located, the inner reflector being closer to the optical axis than the outer reflector, the inner and outer reflectors each having an inner reflective surface and an outer backing layer, the inner reflective surface of the outer reflector facing the backing layer of the inner reflector;a foil trap configured to collect debris from the EUV radiation source, the foil trap being between the EUV radiation source and the reflector assembly;a housing constructed and arranged to contain the reflector assembly and the foil trap, the reflector assembly being connected to the housing via a first wall, and the foil trap being connected to the housing via a second wall;a chamber between the foil trap and the reflector assembly, the chamber being defined by the housing, the first wall, and the second wall; anda pump configured to create a vacuum in the chamber. 12. An assembly according to claim 11, wherein the housing is constructed and arranged to contain the EUV radiation source. 13. An assembly according to claim 11, further comprising a second pump configured to evacuate a space in the housing behind the reflector assembly. 14. An assembly according to claim 11, wherein the outer backing layer of the inner reflectors is covered with a reflective layer having a reflectivity of between 0.7 and 0.99 for wavelengths between 0.1 and 100 μm. 15. An assembly according to claim 11, wherein the outer backing layer of the outer reflector is covered with a radiative layer having a emissivity of between 0.6 and 0.95 for wavelengths between 0.1 and 100 μm. 16. An assembly according to claim 15, wherein the radiative layer comprises carbon. 17. An assembly according to claim 11, wherein the inner reflective layer comprises a noble metal. 18. An assembly according to claim 17, wherein the noble metal comprises gold or ruthenium. 19. An assembly according to claim 11, wherein the inner and outer reflectors are substantially coaxial and extend substantially rotationally symmetric around the optical axis. 20. An assembly according to claim 11, wherein at least the outer reflector comprises radiation fins.
	summary
059178744	claims	1. A target for irradiation of a sample by a particle beam to produce a radioisotope comprising: a body having a depression in a front side for holding said sample, and cooling fins on a backside opposite said depression; a foil sealingly joined to said body front side to cover said depression; a perforate grid fixedly joined to said body atop said foil for supporting said foil, and for transmitting said particle beam therethrough; and means for circulating a coolant over said fins to cool said body during said particle beam irradiation of said sample in said depression. a housing joined to said body around said cone to define a plenum therebetween; and an inlet and outlet disposed in said housing in flow communication with said plenum for circulating said coolant therethrough to remove heat from said body. said depression is shallow in depth for allowing said particle beam to irradiate substantially all said sample therein to produce said radioisotope; and said grid is thin with a thickness of about said depression depth for conducting heat from said foil to said body. 2. A target according to claim 1 wherein said body further includes a cone extending from said backside behind said depression, and said fins are disposed on said cone. 3. A target according to claim 2 wherein said cooling means comprise: 4. A target according to claim 3 wherein said cone includes an apex and an opposite base, and said fins are circumferentially spaced apart around said cone and extend axially between said apex and base. 5. A target according to claim 4 wherein said fins are axially straight. 6. A target according to claim 4 wherein said housing inlet is coaxially aligned with said cone apex, and said outlet is spaced radially outwardly therefrom. 7. A target according to claim 3 wherein said grid comprises a disk having a perforate center core for supporting said foil, and a surrounding rim fixedly joined to said body front side for conducting heat thereto. 8. A target according to claim 7 wherein: 9. A target according to claim 7 further comprising a retaining ring fixedly joined to said body to clamp said grid rim thereagainst, and having a central aperture surrounding said grid core. 10. A target according to claim 3 wherein said foil is aluminum and about six microns thin.
047568534	abstract	A process for the conversion into a usable condition of actinide ions contained in the solid residue of a sulfate reprocessing process for organic actinide-containing radioactive solid waste, which are present in the form of water soluble sulfato complexes. The residue is absorbed with water of 1 to 2 molar nitric acid so that the residue or the largest amount of residue goes in the solution. The resulting solution is separated from the insoluble constituents of the residue in case of any insoluble residue, and heated to a temperature in the range of 40.degree. C. below the boiling point of the solution to form a hot solution. To the hot solution is added an aqueous barium nitrate solution having an amount of barium nitrate which corresponds to a small excess of barium ions over the amount required stoichiometrically for complete precipitation of the sulfate ions. The resulting reaction solution is held at a selected temperature in the same range as above for a period in the range of 0.5 to 2 hours. The reaction solution is subsequently cooled to room temperature and then is separated from the barium sulfate precipitate to form a sulfate free actinide-nitrate solution. The sulfate free actinide-nitrate solution obtained after the separation is fed to an extractive reprocessing process of exposed nuclear fuel-and/or fertile materials, the aqueous phases of which are nitric acidic.
	summary
	abstract	A first antiradiation concrete includes a metallic aggregate having a grain size of up to 7 mm, and at least 5.0% by weight, in particular at least 7.8%, of a boron-containing aggregate having a grain size of up to 1 mm and being finer-grained than the metallic aggregate. A second antiradiation concrete includes a boron-containing aggregate having a grain size of up to 1 mm, and between 80 and 90% by weight, in particular 85 to 89%, of a metallic aggregate having a grain size of up to 7 mm. For the second concrete, the boron-containing aggregate is between 1.0 and 1.5% by weight. To achieve a shielding action that absorbs as much heat and radiation as possible, an antiradiation shell (2) has a wall region (2a to 2z) formed from the first or second antiradiation concrete where each has a boron-containing aggregate with a grain size up to 1 mm and a metallic aggregate grain size up to 7 mm.
	description	1. Field of the Invention The present invention relates to an electron microscope for imaging a specimen by focusing an electron beam (hereinafter may be referred to as the “electron probe” or simply as the “probe”) onto the specimen, scanning the probe over the specimen, detecting the electrons transmitted through the specimen by an electron detector, and visualizing the output signal from the detector in synchronism with the electron beam scanning. More particularly, the invention relates to a method of measuring aberrations by an electron microscope equipped with an illumination system aberration corrector by the use of a Ronchigram and to a method and apparatus for correcting aberrations. 2. Description of Related Art In transmission electron microscopy, a method of imaging a specimen by focusing an electron beam onto the specimen, scanning the beam over the specimen, detecting the electrons transmitted through the specimen by an electron detector, and displaying the output signal from the detector as a visible image in synchronism with the electron beam scanning is known as STEM (scanning transmission electron microscopy) imaging. The spatial resolution of STEM images is affected by various aberrations in the electron beam hitting the specimen. In recent years, apparatus capable of obtaining smaller electron beam diameters than heretofore have been put into practical use by incorporating an aberration corrector into the illumination system, the corrector being capable of correcting spherical aberration. The following two methods are known to measure aberrations in electron beams in such apparatus. 1) Method of correcting aberrations using a probe profile calculated by Fourier analysis. An image of a just focus and an underfocused (or overfocused) image are taken from dark field images of a reference specimen of gold particulates on the order of nanometers. A probe profile is calculated from the image of the just focus and from the underfocused or overfocused image by Fourier analysis, and aberrations are estimated. Parameters of various deflection systems and a stigmator are varied from the estimated aberrations, thus correcting the aberrations. This method uses no Ronchigram. The Ronchigram is an image of a specimen projected to an infinitely distant point as viewed from the specimen (back focal plane) by means of an electron beam focused onto the specimen in the STEM imaging mode. 2) A Ronchigram of a reference specimen (particulates of gold) is created and observed. Aberrations are calculated from variations in magnification caused by positional shift across the Ronchigram (in a quite small angular region). When the variations in the magnification due to shifting are calculated, the electron beam is moved across the specimen. The amount of movement of the Ronchigram made between, before and after the movement of the beam is used. The parameters of the systems of deflection and a stigmator are varied using the calculated aberrations. In this way, the aberrations are corrected. This method uses a Ronchigram. One known apparatus of this kind, for example, as described in U.S. Patent Application Pub. No. 2003/0001102 images an object by means of a beam of particles focused onto the object, recording the image, repeating the process steps carried out until the recording step using underfocused and overfocused beams, Fourier-transforming the images, dividing the Fourier transform of the overfocused image by the Fourier transform of a focused image, inverse transforming the quotient (result of the division), dividing the Fourier transform of the underfocused image by the Fourier transform of the focused image, inverse transforming the result of the division, determining a brightness profile of the probe (i.e., images of the light sources of overfocused and underfocused images), determining the asymmetry of the contour about the center of the image, the width of the contour (especially, the half value width), and/or the curvature of the contour about the center, and using the differences in the probe contour for the different parameters to determine the aberrations in the image. Another known apparatus using a beam of charged particles, for example, as described in U.S. Pat. No. 6,552,340 is designed to minimize the optical aberrations and includes a source of the charged particles, a probe-forming system of charged-particle lenses, a plurality of two-dimensional detectors, a power supply, a computer, and preferred software. This apparatus automatically corrects aberrations. The above-described known methods have the following problems. Any method of the above-described techniques uses a reference specimen. Where an actual specimen is observed using this method, it is necessary to replace the specimen. Furthermore, in order to search for a desired specimen location to be observed, the operating mode may be switched from STEM mode to TEM mode. This induces drifts of varying extents in the systems of deflection and stigmator. When a specimen is observed in practice, various aberrations which should have been corrected vary due to drift (i.e., timewise variations of the magnetic field produced by the lenses). There is the problem that ultrahigh-resolution images cannot be obtained due to the introduced aberrations. The present invention has been made in view of the foregoing problems. It is an object of the present invention to provide a method of measuring aberrations using a Ronchigram of an amorphous portion (which may be on the order of nanometers long at an end of the specimen) actually present in a specimen in such a way that residual aberrations can be adjusted through observation of the Ronchigram. It is another object of the present invention to provide method and apparatus of correcting aberrations using such a Ronchigram. In an aberration corrector for use in an illumination system, the adjustive method for correcting aberrations is important. The shape of a Ronchigram is affected by residual aberrations. A human operator grasps the kinds of the residual aberrations by observing the Ronchigram and corrects the aberrations. Furthermore, a Ronchigram, i.e., shadow image, is captured, and the amounts and magnitudes of the aberrations are automatically calculated. (1) A method of measuring aberrations according to a first embodiment of the present invention uses an electron microscope having a function of displaying an image of a specimen by focusing an electron beam onto the specimen, scanning the beam over the specimen, detecting electrons transmitted through the specimen by an electron detector, and visualizing the output signal from the detector in synchronism with the electron beam scanning. In this method, autocorrelation of local regions on a Ronchigram of an amorphous specimen is taken, and aberrations in the electron beam formed from local angular regions on the aperture plane are detected from the autocorrelation or from the Fourier transform of the autocorrelation. Based on the results of the detection, the aberrations are calculated. (2) A method of measuring aberrations according to a second embodiment of the present invention is based on the first embodiment and further characterized in that a Gaussian function is used as a function representing the autocorrelation. (3) A method of measuring aberrations according to a third embodiment of the present invention is based on the first embodiment and further characterized in that when the autocorrelation is analyzed, the isocontrast portion of the autocorrelation is fitted using an elliptical function. (4) A method of measuring aberrations according to a fourth embodiment of the present invention is based on any one of the first through third embodiments and further characterized in that in order to find the absolute values of aberrations in the electron beam, parameters indicating variations in the aberrations in the electron beam are normalized using the amount of positional deviation from the focus occurring when the Ronchigram was obtained and the distance to a just focus. (5) A method of measuring aberrations according to a fifth embodiment of the present invention is based on any one of the first through third embodiments and further characterized in that in order to find the absolute values of aberrations in the electron beam, two Ronchigrams are taken at different focal positions and that parameters indicating the aberrations in the electron beam are normalized using the differential distance between the focal positions. (6) A method of measuring aberrations according to a sixth embodiment of the present invention is based on any one of the first through fifth embodiments and further characterized in that variations in geometrical aberrations caused when the energy of the electron beam directed at the specimen was varied are detected as variations in local regions of the Ronchigram and that a chromatic aberration coefficient is measured from the variation in the energy of the electron beam and from the amount of focal shift. (7) A method of correcting aberrations according to a seventh embodiment of the present invention uses a method of measuring aberrations as set forth in any one of the first through sixth embodiments. (8) An electron microscope according to an eighth embodiment of the present invention has a function of displaying an image of a specimen by focusing an electron beam onto the specimen, scanning the beam over the specimen, detecting electrons transmitted through the specimen by an electron detector and visualizing the output signal from the detector in synchronism with the electron beam scanning, and an aberration corrector for use in an illumination system. The electron microscope has first calculation device for taking autocorrelation of minute regions on a Ronchigram of the specimen that is amorphous, detection device for detecting aberrations in the electron beam formed from local angular regions on an aperture plane from the autocorrelation or from Fourier analysis of the autocorrelation, second calculation device for calculating aberrations based on results of the detection, and control device for the aberration corrector for correcting the aberrations based on results of calculations performed by the second calculation device. According to the first embodiment, the aberrations can be automatically corrected using the Ronchigram. According to the second embodiment, a Gaussian function can be used as a function representing the autocorrelation. According to the third embodiment, the autocorrelation can be analyzed more precisely by fitting the isocontrast portion of the autocorrelation using an elliptical function. According to the fourth embodiment, the absolute values of the aberrations in the electron beam can be found. According to the fifth embodiment, the absolute values of the aberrations in the electron beam can be found. According to the sixth embodiment, a chromatic aberration coefficient can be measured. According to the seventh embodiment, the aberrations can be corrected. According to the eighth embodiment, the aberrations can be corrected automatically using the Ronchigram. Other objects and features of the invention will appear in the course of the description thereof, which follows. Embodiments of the present invention are hereinafter described in detail with reference to the accompanying drawings. FIG. 1 is a block diagram showing an example of apparatus for implementing an embodiment of the present invention. The apparatus has an electron gun 1 for producing an electron beam, a first condenser lens 2 including a stigmator (i.e., astigmatism-correcting element), and an aberration corrector 3 incorporated in the illumination system and including a stigmator for correcting aberrations in the illumination system of the apparatus. The aberration corrector 3 of the illumination system includes electron beam-deflecting elements and the stigmator. The apparatus further includes a second condenser lens 4 having deflectors, a scan assembly 5 for scanning an electron beam, an objective lens 6, a specimen stage 7, an imaging lens system 8 including intermediate and projector lenses, and an observation chamber 9 for observing a projected image. A projection screen 10 (removable) and a CCD camera 11 are equipped in the observation chamber 9. The apparatus further includes a high-voltage controller 12 for applying a high voltage to the electron gun 1, an aberration correction controller 13 for controlling the aberration corrector 3, an amplifier 14 for driving a power supply to the lenses, scan controller 15 for controlling the scan assembly 5, and an image-processing device 16 for processing the image signals from the CCD camera 11, an interface 17, a computer 18, a display device 19, and an input device 20. A specimen (not shown) is held in the specimen stage 7. The operation of the apparatus constructed in this way is next described briefly. The electron beam emitted from the electron gun 1 is focused by the first condenser lens 2, and astigmatic correction is performed. Then, the beam enters the aberration corrector 3 in the illumination system. In the aberration corrector 3, the beam is deflected in two dimensions, and corrections of aberrations including spherical aberration are made. The electron beam from the front focal point of the objective lens hits the specimen (not shown). At this time, the electron beam transmitted through the specimen is focused at the back focal point of the objective lens 6 and then an image is projected onto the projection screen 10 in the observation chamber 9 via the imaging lens system 8. The operator can view alternatively the projected image on the projection screen 10 or taken image by the CCD camera 11 on the display device 19 and can operate the apparatus using the input device 20. The relation between aberrations in the electron probe and a Ronchigram is next described by referring to FIG. 6, where the angular space plane of the front focal plane (or aperture plane of the first condenser lens 2) of the objective lens 6 is referred to as the aperture plane. The angular space plane is denoted by convergent angle α and azimuthal angle θ. Certain angular regions on the aperture plane such as T1, T2, and T3 are referred to as the local angular regions on the aperture plane. A Ronchigram is observed on the projection screen 10 in the observation chamber 9. Figures at positions infinitely far apart from the specimen (corresponding to different angles of the probe) are projected onto the Ronchigram. There is a 1:1 relationship between each local angular region on the aperture plane and a corresponding local angular region on the Ronchigram. Actual operation for correcting aberrations is next described. FIGS. 2a-2e illustrate processing for correction of aberrations, and shows half-toned images showing examples of the main window displayed on the viewing screen of a display unit in accordance with one embodiment of the present invention. FIGS. 3a-3f and FIG. 4 show similar images. A case in which manual operations are performed is first described. The operating mode of the apparatus is set to scanning transmission electron microscopy (STEM) mode to have a camera length and a scanning magnification permitting easy observation of the Ronchigram. Then, the apparatus is set to spot mode to stop the scanning of the electron beam. The beam is then moved to the amorphous portion at an end of the specimen to observe the Ronchigram. The beam is focused on the specimen by movement (Z motion) along the height of the specimen. The Ronchigram is observed. A pattern of lines is observed in the center indicated by a white circle as shown in FIG. 2a. This pattern is surrounded by patterns of radiating lines. Where the spherical aberration corrector consists of a hexapole element, the Ronchigram is made up of three (P, Q, and R) patterns of radiating lines or six patterns as shown in FIG. 2b. Generally, where there is a spherical aberration corrector, a Ronchigram consisting of multiple patterns of radiating lines is observed. Lines located in the center and directed at a certain direction are eliminated using the stigmator coil. At this time, it is ascertained that the direction of the lines is inverted as shown in FIGS. 2c and 2d while varying the focus. In the final Ronchigram, there is no line having directionality in the center near the just focus as shown in FIG. 2e. Consequently, the two-fold astigmatism can be corrected. Then, the deflection coil is adjusted such that the radiating lines of the patterns observed in peripheral portions become uniform in length as shown in FIGS. 3a-3f. As a result, the radiating lines vary from FIGS. 3a, to 3e or to 3f. Generally, coma can be corrected by adjusting the deflection coil such that all the patterns of radiating lines on the Ronchigram become uniform in geometry. The processing illustrated in FIGS. 2a-2e and FIGS. 3a-3f is repeated a required number of times to obtain a Ronchigram in which the contrast in the central portion as described below is uniform at the just focus. FIG. 4 illustrates processing for correction of aberrations. When the aberrations have been corrected, the central region having no contrast is extended. As described so far, the states of the various aberrations can be seen from variations in the Ronchigram of the amorphous portion of the specimen. In the present invention, the process steps described above are automated. Furthermore, aberrations up to higher orders can be calculated and corrected. From image recognition of the Ronchigram, calculations of aberrations are performed as described below. The aberrations are corrected using the results of the calculations of the aberrations automatically. FIG. 8 is a block diagram showing an example of device and process for correcting the aberrations under computer control. In FIG. 8, the computer 18 includes a first calculation device 30 for taking autocorrelation of minute regions on a Ronchigram of the specimen that is amorphous, a detection device 31 for detecting aberrations in the electron beam formed from local angular regions on an aperture plane from the autocorrelation or from Fourier analysis of the autocorrelation, and a second calculation device 32 for calculating aberrations based on results of the detection. The aberration correction controller 13 controls the aberration corrector 3 in the illumination system for correcting the aberrations based on results of calculations performed by the second calculation device 32. In the method given below, aberration functions are found by finding derivatives of geometrical aberrations from autocorrelation functions of local regions of a Ronchigram. An aberration function χ referred to herein represents the sum of wavefront aberrations. In high-resolution electron microscopy, only on-axis aberrations are treated and so the following aberrations are discussed. Each aberration has an amplitude portion and an angular portion. aberration function χ=focal shift+2-fold astigmatism+3-fold astigmatism+on-axis coma+spherical aberration+4-fold astigmatism+star aberration+5-fold astigmatism+three-lobe aberration+4th-order on-axis coma+5th-order spherical aberration+6-fold astigmatism . . . . A method for taking autocorrelation of minute regions on a Ronchigram performed by the first calculation device 30 is next described. Let ƒ be a function of interest. An autocorrelation function is given by Eq. (1) below.∫ƒ(s) ƒ(s−x)ds (1) An aberration function χ on an aperture plane is represented by a sum of wavefront aberration functions. Let G be a geometrical aberration. Let e1 and e2 be base vectors defining a two-dimensional space. Then, we have G → = ( G ⁢ ⁢ e ⁢ ⁢ 1 , G ⁢ ⁢ e ⁢ ⁢ 2 ) = λ 2 ⁢ ⁢ π ⁢ ( ∂ x ∂ e ⁢ ⁢ 1 , ∂ x ∂ e ⁢ ⁢ 2 ) ( 2 ) For example, (e1, e2) assumes the form (α, θ), (X, Y). Let P be a function indicating positional information about a specimen. A Ronchigram is given by P (Ge1, Ge2). Expanding Ge1 and Ge2 about eI and eII (where eI and eII are unit vectors in (α, θ), (X, Y) directions) in a two-dimensional plane gives rise to:Ge1=GeI+Ade1+Bde2Ge2=GeII+Bde1+Cde2where A = ∂ G ⁢ ⁢ e ⁢ ⁢ 1 ∂ e ⁢ ⁢ 1 \| eIeII B = ∂ G ⁢ ⁢ e ⁢ ⁢ 1 ∂ e ⁢ ⁢ 2 \| eIeII C = ∂ G ⁢ ⁢ e ⁢ ⁢ 2 ∂ e ⁢ ⁢ 2 \| eIeII } ( 3 ) Note that \|eI, eII included in Eq. (3) means that the values of eI, eII are entered into e1 and e2 that are the results of partial derivatives. Functions are still left behind only if partial differentiation is performed and, therefore, the values of eI, eII are substituted into the variables of the function. In consequence, the values of A, B, and C are determined specifically. Then, the variations in the aberrations in the electron beam are indicated by the variations in the unit vectors. With respect to a specimen not dependent on position, such as an amorphous specimen, a Ronchigram is given byP(Ade1+Bde2, Bde1+Cde2)In this way, in local regions of a Ronchigram, geometrical aberrations in an electron probe formed from local angular regions on the aperture plane can be seen. A method for detecting aberrations in the electron beam formed from local angular regions on an aperture plane from the autocorrelation performed by the detection device 31 is next described. The probe profile (i.e., aberrations in the probe) can be found by Fourier analysis of the autocorrelation function. If an autocorrelation function of an image of an amorphous specimen is given by a Gaussian function, i.e., exp ⁡ ( - ( ( del ⁢ ⁢ 1 ) 2 + ( de ⁢ ⁢ 2 ) 2 ) σ 2 ) ( 4 ) an autocorrelation function in each local region on the Ronchigram is given by exp ⁡ ( - ( ( Adel ⁢ ⁢ 1 + Dde ⁢ ⁢ 2 ) 2 + ( Bde ⁢ ⁢ 1 + Cde ⁢ ⁢ 2 ) 2 ) σ 2 ) ( 5 ) Therefore, A, B, and C are measured by fitting (Ade1+Bde2)2+(Bde1+Cde2)2 from an autocorrelation diagram. In the description above, the autocorrelation function of the amorphous specimen image is a Gaussian function. It is not always necessary that the autocorrelation function be a Gaussian function. For example, when an autocorrelation is analyzed, the isocontrast portion of the autocorrelation diagram may be fitted using an elliptical function which results in:(Ade1+Bde2)2+(Bde1+Cde2)2=K (6)where K is a constant. A method for calculating aberrations performed by the second calculation device 32 based on results of the detection is next described. FIGS. 5a and 5b show an actual Ronchigram and an autocorrelation diagram. As shown in FIG. 5a, the whole area of the Ronchigram is divided into local regions. In the illustrated example, the whole area is divided into 3×3 small regions. FIG. 5b shows the autocorrelation function in the local regions shown in FIG. 5a and an example of fitting them. In FIG. 5b, elliptical white lines indicate that the portions are isocontrast portions. A, B, and C are found from the direction and size of the portion surrounded by each white line. To improve the correction accuracy, the whole Ronchigram is divided into about 7×7 small regions as shown in the example of fitting of FIG. 7 in many practical applications. A, B, and C are measured from the autocorrelation functions in the local regions of the Ronchigram. When A, B, and C are measured, the autocorrelation function given in Eq. (1) is used. The absolute values of A, B, and C can be found by performing normalization by the amount of focal shift from the just focus, for example, when a Ronchigram is obtained. The normalization is equivalent to determining σ included in Eq. (5) in a case where a Gaussian function is used as an autocorrelation function. In the method of fitting the isocontrast portion of an autocorrelation diagram using an elliptical function, the normalization is equivalent to determining the constant K included in Eq. (6). Instead of the amount of focal shift from the just focus used for the normalization, the difference between the focal points of two Ronchigrams may be used. An aberration function is calculated using the results of some measurements of A, B, and C and the relationship given in Eq. (3). Based on the calculated aberrations, each corrective element in the aberration corrector 3 is so energized by the aberration correction controller 13 as to cancel the aberrations. In this way, the aberrations are automatically corrected. It is not always necessary that aberrations be automatically corrected under computer control according to the results of calculations. Alternatively, calculated aberrations or amounts of corrections based on the calculations may be displayed on a display device 19 included in the apparatus shown in FIG. 1 and the operator may perform corrective manipulations by using the input device 20 while watching the displayed results. In the above description, a method of correcting geometrical aberrations in an electron probe formed from local angular regions on an aperture plane is described. The method is not always restricted to correction of geometrical aberrations. That is, variations in geometrical aberrations (focal shift) caused by varying the energy of the electron probe (accelerating voltage) directed at the specimen can be detected as variations in the local regions of the Ronchigram. Chromatic aberration coefficient Cc can be measured from the variation in the energy and from the amount of the focal shift, and also chromatic aberration can be corrected. In this way, the present invention can offer a method of measuring aberrations by using observation of a Ronchigram of an amorphous portion (which may be several nanometers long at an end of a specimen) actually present in the specimen, the method being capable of adjusting residual aberrations. Also, method and apparatus of correcting aberrations using such a Ronchigram are offered. Having thus described our invention with the detail and particularity required by the Patent Laws, what is desired protected by Letters Patent is set forth in the following claims.
	claims	1. A tagged excavation element including:an excavation element body; anda tagging device securable to the excavation element body;characterized in that the tagging device includes a radioactive source,wherein the excavation element is a shroud or a tooth of an excavation bucket. 2. The tagged excavation element of claim 1 in which the tagging device is in the form of a sealed radioactive source. 3. The tagged excavation element of claim 2 in which the sealed radioactive source comprises a radioactive material encapsulated in a sealed metal housing. 4. The tagged excavation element of claim 3 in which the sealed metal housing is locatable inside an aperture provided in the excavation element. 5. The tagged excavation element of claim 1 in which the radioactive source has a half-life of between 40 days and 150 days. 6. The tagged excavation element of claim 5 in which the radioactive source has a half-life of between 80 days and 90 days. 7. The tagged excavation element of claim 1 in which the radioactive source is a radioactive metal. 8. The tagged excavation element of claim 1 in which the radioactive source emits gamma radiation at an energy level between 300 keV and 2000 keV. 9. The tagged excavation element of claim 8 in which the radioactive source emits gamma radiation at an energy level between 850 keV and 1500 keV. 10. The tagged excavation element of any one of the preceding claims in which the radioactive source is selected from the group including scandium (Sc), tantalum (Ta), terbium (Tb) and antimony (Sb). 11. The tagged excavation element of any one claims 1 to 9 in which the radioactive source is a radioisotope of the element scandium (Sc), scandium 46 (46Sc). 12. A method of manufacturing a tagged excavation element, the method including the steps of:providing an excavation element body;providing a tagging device including a radioactive source; andsecuring the tagging device to the excavation element body,wherein the excavation element is a shroud or a tooth of an excavation bucket. 13. The method of claim 12 in which the tagging device is in the form of a sealed radioactive source. 14. The method of claim 13 in which the sealed radioactive source comprises a radioactive material encapsulated in a sealed metal housing. 15. The method of claim 14 in which the sealed metal housing is locatable inside an aperture provided in the excavation element. 16. The method of claim 12 in which the radioactive source has a half-life of between 40 days and 150 days. 17. The method of claim 16 in which the radioactive source has a half-life of between 80 days and 90 days. 18. The method of claim 12 in which the radioactive source is a radioactive metal. 19. The method of claim 12 in which the radioactive source emits gamma radiation at an energy level between 300 keV and 2000 keV. 20. The method of claim 19 in which the radioactive source emits gamma radiation at an energy level between 850 keV and 1500 keV. 21. The method of any one of claims 12 to 20 in which the radioactive source is selected from the group including scandium (Sc), tantalum (Ta), terbium (Tb) and antimony (Sb). 22. The method of any one of claims 12 to 20 in which the radioactive source is a radioisotope of the element scandium (Sc), scandium 46 (46Sc). 23. A method of detecting the displacement of an excavation element, the method including the steps of:providing an excavation element tagged with a tagging device including a radioactive source, the excavation element comprising a shroud or a tooth of an excavation bucket;providing a radiation detector; anddetecting a change in radiation when the excavation element is displaced relative to the radiation detector. 24. The method of claim 23 in which the radiation detector is mounted on part of a structure to which the excavation element is secured, and in which the radiation detector detects a reduction in radioactivity when the excavation element is displaced away from the structure. 25. The method of claim 24 in which the structure is the body of an excavation apparatus. 26. The method of claim 25 in which one or multiple radiation detectors are provided on the excavation apparatus. 27. The method of 25 in which the radiation detector is mounted on a structure at one or more locations adjacent a route along which excavated material is displaced, and in which the radiation detector detects an increase in radioactivity when the excavation element is displaced together with the excavated material. 28. The method of claim 27 in which the structure is a gantry past which the excavated material is displaced.
	description	The present invention relates to a method for treating electric arc furnace (EAF) dusts. In particular, the invention relates to a method for removing the 137Cs content from polluted EAF dusts. Furthermore, the present invention relates to a plant for carrying out the method for removing the 137Cs content from polluted EAF dusts. Furthermore, the present invention relates to the use of destabilisation chemical-physical agents, specifically oxidation-reduction or redox agents, for obtaining EAF dusts decontaminated from 137Cs. In the ferrous scrap based steel manufacturing industries, the accidental melting of radioactive sources in the melting furnaces represents an unfortunately recurring event, which has been involving several factories in Italy, Europe and worldwide over the last few years. The continuous improvement in the control systems of ferrous materials entering plants has certainly decreased the number of such events; however, the different control phases, starting from the radiometric examination of incoming materials up to the final visual inspections, can not ensure that the scrap is totally free from foreign materials, in particular from radioactive sources. When such unfortunate and unintentional events involve orphan sources of 137Cs, said radioactive element completely converts into the vapour state during the melting process (temperature of the melting furnace: 1,400° C.-1,700° C.) and then, upon cooling, it mixes with the dusts produced during said melting process; such dusts are not released to the outside environment thanks to suitable and efficient filtration systems. The activity concentration present in such dusts depends on the characteristics of the molten source, whose activity can vary from a few MBq to hundreds GBq, but also on the dispersion and mixing of the polluted dusts with other non-radioactive dusts already present in the plant. Therefore, the amount of polluted dusts can affect a total mass of several hundred tons, with activity concentrations varying from values lower than 380 Bq/kg, which is the threshold generally accepted for freely handling the dusts without radiological prescriptions, up to values exceeding 500,000 Bq/kg. As a consequence, such radioactive dusts must be either isolated or subjected to suitable decontamination treatments so as to declassify them to non-radioactive dusts. In the reference technical field the most common practice consists in segregating inside suitable storage sites; it is clear that this approach is not conclusive in terms of decontamination. Furthermore, in the specific case of 137Cs, the decay half-life is more than 30 years; it follows that the segregation time to lower the radioactivity value below the unconditional release threshold (380 Bq/kg) is about 300 years. The decontamination treatments studied so far are very few; the following are the only two publications found in which 137Cs is explicitly mentioned as a pollutant of EAF dusts: J. M. Arnal et al., “Management of Radioactive Ashes after a 137Cs Source Fusion Incident”, 11th IRPA—International Radiation Protection Association International Congress, Madrid, Spain, May 23-28, 2004 and the U.S. Pat. No. 5,570,469 granted on Oct. 29, 1996 in the name of Soderstrom et al. The treatment described in the aforementioned scientific publication in the name of J. M. Arnal et al. provides for leaching the polluted dusts with distilled water to which a non-radioactive salt of cesium (CsCl) is added to take advantage of the effect of isotopic exchange; the process is carried out in an acid medium (pH approximately 5) and at room temperature; the duration of the complete extraction process is approximately 24 hours; the yield of the treatment, after four stages of extraction, was 90%. The treatment described in the aforementioned U.S. Patent provides a two-stage leaching process, both stages being carried out in an acid medium; in the second stage a non-radioactive salt of cesium is added (as in the previous case); the yield of the treatment is approximately 90%. More precisely, the treatment described in the aforementioned U.S. Patent provides the solubilisation in two stages of the matrix, mainly consisting of Fe and Zn, to allow the recovery of the Cs brought in solution; the recovery of the Cs according to this invention takes place by ion exchange after the first leaching or by ion exchange after having carried out also a second leaching and after that Fe and Zn have been separated by precipitation from the solution. It is highlighted that the process described in the above Soderstrom patent is a simple leaching process, which does not involve reductive and/or oxidative effects; specifically, according to this patent (see column 5, lines 31-50, and column 7, lines 3-6), the solubilisation of the matrix takes place thanks to the use of a strong acid, such as nitric acid, phosphoric acid, sulphuric acid and hydrochloric acid, the last two being the preferred ones. As it is known from the field literature, the nitric acid is an excellent oxidiser while the hydrochloric acid is not deemed to be an oxidiser: nevertheless the latter is preferable to the former, that in fact is never used in the reported examples; on this basis, our opinion is that also the preferred choice of the sulphuric acid for the leaching according to the Soderstrom patent does not depend on its oxidant characteristics that, though being peculiar, are never mentioned in the patent. Moreover the only element present in reduced phase in the EAF dusts is Fe, which is present in part as Fe(II); it is known, however, that the sulphuric acid is not able to oxidise the Fe(II) to Fe(III) and that this operation requires the presence of a suitable oxidant such as, for example, the permanganate ion. The greater ease of use, in industrial terms, of the sulphuric acid appears to be given also by the subsequent neutralisation of the acid solution with CaO (see column 8, lines 33-36) that, by reacting with H2SO4, forms CaSO4 almost insoluble; the formation of CaSO4, besides facilitating the filtration as explained, also causes a strong decrease in the concentration of residual radioactive activity of 137Cs for simple mass increase (such a dilution in the concentration of residual radioactive activity would not be obtained, for example, with the acid hydrochloric owing to high solubility of calcium chloride). The two aforesaid methods, at the moment the only known ones specific for the decontamination of 137Cs present in polluted EAF dusts, are not very convenient both in economic terms, for the complexity of the provided operations, and in terms of decontamination efficiency, that in both cases is expected to be 90%. More promising than the methods described above appears to be the alkaline leaching under well-defined conditions (pH, temperature and contact times), as disclosed in the Italian Patent No. IT 1 358 799. The method according to the aforesaid Italian Patent provides that the dusts contaminated with radioactive materials are subjected to washing with water under conditions of pH=9-13 (EAF dusts, in fact, contain oxides of Ca, K and Na that, in the presence of water, create a definitely basic medium), preferably under stirring and at a temperature of at least 60° C.; the yield of the treatment exceeds 95%. The method according to the aforesaid Italian Patent has been successfully applied for totally decontaminating about 500 tons of dusts with 137Cs activity concentration up to 25,000 Bq/kg, with an average value of about 5,000 Bq/kg. Despite the above positive performance (effective decontamination yield >95%), said existing treatment would not be adequate to achieve decontamination from 137Cs below 380 Bq/kg, 1,000 Bq/kg or 10,000 Bq/kg, with initial contamination average values of 7,600 Bq/kg, 20,000 Bq/kg or 200,000 Bq/kg respectively (assuming a precautionary yield of 95%). We want to point out here that, from the radiological point of view, the value of 380 Bq/kg represents a level generally accepted for the unconditional release; the value of 1,000 Bq/kg is the level below which the material is considered “non-radioactive”; the value of 10,000 Bq/kg is the maximum acceptable level for controlled sites for hazardous wastes; as to levels greater than 10,000 Bq/kg, the materials must be confined in special radioactive storehouses. Therefore, as already mentioned above and particularly in the presence of radioactive materials having a level greater than 10,000 Bq/kg, until the present time, to our knowledge, treatment technologies in alternative to the confinement (with the exception of the abovementioned case) have never been taken into account. Therefore there still exists the need of identifying a method having better effectiveness, i.e. capable of removing the 137Cs content below 380 Bq/kg starting from polluted EAF dusts with high average values (even exceeding 100,000 Bq/kg). Moreover, the Inventors have observed that the method according to the aforesaid Italian Patent allows to decrease the content of 137Cs present in the polluted dusts of about 20-25 times, this representing a substantially insuperable limit because the repetition of the leaching operations does not lead to a further decrease of the radioactive waste in the treated dusts; in other words, at least part of the 137Cs appears to be under a chemical-physical form that can not be subjected to alkaline leaching. One possible explanation for this occurrence could arise from the composition of the EAF dusts, whose chemical and mineralogical characteristics have been reported in several studies in the literature such as, for example, F. M. Martins et al., “Mineral phases of weathered and recent EAF dust”, J. of Hazardous Material 154 (2008) 417-425; J. C. M. Machado et al., “Characterization Study of EAF Dust Phases”, Materials Research 9 (2006) 41-45; C. Z. Rizescu et al., “Characterization of Steel Mill EAF dust”, Advances in Waste Management—ISSN:1790-5095 ISBN:978-960-474-190-8. A typical chemical composition of the EAF dusts comprises (% by weight): Fe 30-40%; Zn 10-15%; Ca 5-10%; Si 3-4%; Mg 1-2%; K 1-2%; Pb 1-2%, Mn 1-2%, Al 0.5-1%, Cu 0.2-0.5%; S 0.2-0.5%. From the mineralogical point of view the presence of several species is known such as, for example, the Franklinite (ZnFe2O4), the Zincite (ZnO), the Magnetite (Fe3O4), the Laurionite (Pb(OH)Cl), thereby justifying the hypothesis that at least part of the 137Cs can be present either as Cs-ferrite or as (K+, Cs+)-β-ferrite [see: Shigero Ito et al., Solid State Ionics 72(1994)300], these forms being stable under alkaline conditions. On the other hand the magnetite, and other ferrites, are well known to be able to capture the cesium [see for example: Tao Yang et al., Surface Science 603(2009)78]; the subsequent elution of cesium absorbed on the magnetite and other ferrites could be done by acidification, but bearing in mind the simultaneous solubilisation of other species present and sensitive to the acid medium. Since the above-mentioned method of the alkaline leaching according to the Italian Patent No. 1 358 799 is limited in terms of removal efficiency in the decontamination treatments, especially for usefully treating dusts polluted with a higher average content of 137Cs, it could be considered to carry out an acid leaching after the alkaline leaching, which could be useful, in principle, to attack the ferrites; however, this would involve a significant dissolution of the iron oxides also present (specifically, Fe2O3) that would take place much more easily than the attack of the same ferrites, creating a situation completely inconvenient for the subsequent separation of the 137Cs. Therefore there still exists the need of identifying a method avoiding the solubilisation of the iron oxides and allowing a more specific attack of the 137Cs present in the polluted EAF dusts. Finally, there exists a felt need of identifying a method also involving a decrease in the consumption of materials used in the decontamination treatment. There exists also a felt need of providing a plant for carrying out the method suitable to remove the 137Cs from polluted EAF dusts and intended to achieve the objects described above. In particular the European Patent application no. EP 0 419 777 A1 filed on Jul. 2, 1990 in the name of Rockwell International Corporation is known, in which a plant for treating nuclear reactors fuel is described; specifically said plant operates at 400° C. when the fuel is oxidised with O2 and at 600° C. when the fuel is reduced with H2: these operations pulverise the fuel that was previously in the form of pellets (see column 2, lines 11-25) in order to prepare it for the subsequent electrolytic reduction, through which the uranium is reduced to metal in a system of molten fluorides (see column 2, lines 46-51). The plant described in the aforementioned application specifically aims to recover UO2 fuel without fission products (among these, the radioactive cesium), because they interfere with the fission reaction, but it does not allow the removal of cesium; in fact, the separation of Cs, during the initial oxidation and reduction stages mentioned above, occurs in an inadequate degree (40-60%) for the purposes of the fuel regeneration and it is mainly obtained during the subsequent electrolytic separation of uranium in molten salts. The reason for such insufficient separation possibly resides in the fact that the plant according to the abovementioned application operates at limited temperatures, while it is still unmet the need of a plant, specifically of a pyro-metallurgical plant, able to operate at temperatures such as to permit the complete separation of cesium. It is therefore an object of the present invention to provide a method for overcoming the drawbacks of the prior technical solutions, both in terms of materials consumption and in terms of decontamination effectiveness. In particular, it is an object of the present invention to provide a method for removing the 137Cs content below 380 Bq/kg starting from polluted EAF dusts with high average values (even exceeding 100,000 Bq/kg). It is also an object of the present invention to provide a method overcoming the limits existing at the moment in terms of removal effectiveness of the 137Cs content present in the polluted dusts. It is also an object of the present invention to provide a method avoiding the solubilisation of the iron oxides during the decontamination treatment of 137Cs polluted EAF dusts. It is, finally, an object of the present invention to provide a method also involving a decrease in the consumption of materials used in the decontamination treatment. Furthermore, the present invention provides a plant for carrying out the method for removing the 137Cs from polluted EAF dusts. Furthermore, the present invention provides the use of destabilisation chemical-physical agents, specifically oxidation-reduction or redox agents, for obtaining EAF dusts decontaminated from 137Cs; these chemical-physical agents essentially cause a variation of the oxidation state of some components of the matrix, which can be realised both in the hydro-metallurgical field and in the pyro-metallurgical field. These and other objects of the present invention are achieved by means of the method comprising the features claimed in the annexed claims, which form integral part of the present description. Starting from the Inventors' observation of the fact that, as previously described in detail, 137Cs is present in the polluted dusts, at least in part, under a chemical-physical form that can not be subjected to alkaline leaching, the method according to the present invention aims to facilitate the cesium release by destabilising the absorption system, for example by carrying out a chemical reduction under the same alkaline conditions. The choice of the alkaline conditions, and more precisely the implementation of a method in a single stage in an alkaline medium, allows to leave substantially unaltered, i.e. to not dissolve, the ferrous matrix in both the provided attack modes, reductive or oxidative; as a consequence of the reductive or oxidative treatment, the stability of the complexes containing the radioactive cesium is destroyed—in other words, a destabilisation is therefore realised—resulting in the release of cesium. It is worthy to explain here that, in particular, the method according to the present invention does not require the use of sulphuric acid that, since is a strong acid, actually dissolves the matrix itself contrary to what is sought with the present invention. The Inventors believe that also the electrochemical reduction of the iron oxides, in an alkaline medium, falls within the wider scope of the reduction reactions. While the invention is susceptible of various modifications and alternative implementations, some embodiments thereof will be described below in detail, in particular by means of illustrative examples. It should be understood, however, that there is no intention to limit the present invention to the disclosed specific embodiments but, on the contrary, the invention intends to cover all the modifications, alternative and equivalent implementations falling within the scope of the invention as defined in the attached claims. In the following description, therefore, the use of “e.g.,” “etc.,” and “or” denotes non-exclusive alternatives without limitation unless otherwise noted. The use of “including” means “including, but not limited to,” unless otherwise noted. In the following description, moreover, the term “polluted EAF dusts” denotes dusts collected downstream the melting furnace, after the cooling step, inside the filtration system or in the dusts storage tank. The method for removing the 137Cs from polluted EAF dusts according to the present invention comprises the following steps: i) providing an amount of EAF dusts polluted with 137Cs, even with an initial average value >10,000 Bq/kg; ii) subjecting the dusts to a chemical-physical destabilisation reaction, specifically to an oxidation-reduction or redox reaction; and iii) following the chemical-physical destabilisation reaction, specifically the oxidation-reduction or redox reaction, obtaining the release of cesium. For clarity's sake, it is emphasised that the method according to the present invention does not provide two different reactions in steps ii) and iii); the release of cesium according to step iii) is the result of the chemical-physical destabilisation reaction by oxidation-reduction according to step ii) and it is not an autonomous step temporally subsequent to said destabilisation reaction. At this point we want to specify that the EAF dusts polluted with 137Cs treatable by the method according to the present invention may have any value of the initial radioactivity concentration, although said method is mainly directed to the treatment of dusts having an initial average value also >10,000 Bq/kg as indicated above; the method according to the present invention works independently of the initial concentration and the value of 10,000 Bq/kg has, at the present time, a reference table value since it represents the limit beyond which the regulations in force require expensive containment systems for the polluted dusts. Optionally, after the step referred to in point i), the polluted EAF dusts can be subjected to a pre-treatment substantially consisting in an alkaline leaching with water. As mentioned above, the main difficulty to be overcome, for which the Inventors have surprisingly found the present technical solution, is represented by the absorption of cesium on magnetite and other ferrites. To this end, i.e. to solve the technical problem of the absorption of cesium on magnetite and other ferrites, the polluted EAF dusts are subjected to a chemical-physical destabilisation reaction. The chemical-physical destabilisation (for example of the magnetite) can occur either by reduction or by oxidation of the polluted EAF dusts; the Inventors believe that also the electrochemical reduction of the iron oxides, in an alkaline medium, falls within the wider field of the reduction reactions. In turn, the chemical-physical destabilisation can occur both in the hydro-metallurgical field and in the pyro-metallurgical field. Finally it is also possible to combine the chemical-physical destabilisation by oxidation with that by reduction, and even suitably to combine the operation fields. To make clear and unambiguous the meaning of the chemical-physical destabilisation reaction of the polluted EAF dusts according to the present invention, we must start from the characterisation of said EAF dusts that, generically, are a mixture comprising simple and complex oxides. As partially anticipated in the discussion of the prior art, an illustrative chemical composition of the EAF dusts comprises (% by weight; components present as traces excluded): Fe: 25-50; CaO: 4-15; MgO: 1-5; Al2O3: 0.3-0.7; SiO2: 1.5-5; P2O5: 0.2-0.6; MnO: 2.5-5.5; Cr2O3: 0.2-1; Na2O: 1.5-1.9; K2O: 1.2-1.5; Zn: 10-35; Pb: 0.8-6; Cl: 1.5-4, S: 0.5-1, the main species present in said EAF dusts, however, are always the same: ZnO.Fe2O3; FeO.Fe2O3; MgO.Fe2O3; FeO.Cr2O3; Mn3O4; MgO; SiO2; Ca0.15Fe2.85O4 and ZnO, as evidenced by field references such as, for example: Materials Research, Vol. 9, No. 1 (2006), 41-45, Janaina Gonçalves da Silva Maria Machado et al.; Tr. J. of Engineering and Environmental Science, Vol. 23 (1999), 199-207, H. Mordogan, T. Cicek, A. Isik; Ironmaking & Steelmaking, Vol. 35, No. 4 (2008), 315-320, da Silva Mr. Conserva et al., Journal of Hazardous Materials, Vol. 179 (2010), 1-7, P. Oustodakis et al. The EAF dusts, since they are a heterogeneous mixture of oxides, when treated with acids are solubilised and form the salts corresponding to the acids employed. To solubilise the EAF dusts many acids can be used, including the sulphuric acid that, as it will be seen below, does not involve oxidation phenomena. If we assume, for simplicity and by way of explicative example only, that the EAF dusts are formed of the sole iron oxides, therein iron (Fe) is present with different degrees of oxidation (+2 and +3); the acid leaching of the iron oxides having oxidation states II or III forms, respectively, ferrous salts or ferric salts according to the reactions:FeO+2H+=>Fe2++H2OFe2O3+6H+=>2Fe3++3H2O Therefore, the leaching acid attack carries out the above solubilisation action, without performing any oxidation reaction. When operating in an acid medium, for example in the presence of sulphuric acid, to obtain the oxidation of Fe(II) is necessary to use a suitable oxidising agent, such as the ion permanganate, according to the following reaction:5Fe2++MnO4−+8H+=>5Fe3++4H2O+Mn2+wherein the permanganate ion oxidises the Fe(II) to Fe(III), while the manganese is reduced and passes from the state (VII) to state (II); the oxidation state of the sulphur in the SO42− ion, however, remains unchanged, as it does not take part in the reaction. Similarly, when operating in an alkaline medium, to obtain the oxidation of Fe(II) is necessary to use a suitable oxidising agent, such as the permanganate ion, according to the following reaction:3Fe2++MnO4−+2H2O=>3Fe3++MnO2+4OH−wherein the manganese is reduced and passes from the state (VII) to state (IV). For completeness, in a strong alkaline medium the following reaction occurs:MnO4−+e−→MnO42−. Some preferred embodiments of the invention will be illustrated in detail hereinafter; in particular, the invention will be now better described with reference to the following examples. As it will become evident from the examples below, the chemical-physical destabilisation reactions by redox occur in an alkaline medium, i.e. in the condition in which, as previously noted, the 137Cs is present in the polluted dusts, at least in part, in a chemical-physical form not susceptible of alkaline leaching. Examples 1 to 6 show the positive effect obtained with a reducing agent in the extraction of recalcitrant 137Cs present in a sample of dusts already treated with the leaching method (according to the Italian Patent No. 1 358 799); these examples show the percentage of the extracted 137Cs (in addition with respect to the sole leaching) as a function of the concentration of the reducing agent that was used. Example 7 shows the positive effect obtained with an oxidising agent in the extraction of recalcitrant 137Cs present in a sample of dusts already treated with the leaching method. Example 8 compares the advantages obtained when directly using the reducing agent with respect to a prior extraction by leaching. Examples 9 and 10 concern two additional and different ways of destabilisation by reduction. Example 11 concerns the chemical-physical destabilisation by oxidation. Method of Reduction or Oxidation in the Hydro-Metallurgical Field The method for removing the 137Cs from polluted EAF dusts according to a first embodiment, in the hydro-metallurgical field, of the present invention comprises the following steps: i) providing an amount of EAF dusts polluted with 137Cs, having an initial average value also >10,000 Bq/kg; ii) subjecting the dusts to a chemical-physical destabilisation reaction by reduction, also electrochemically, or by oxidation; and iii) following the chemical-physical destabilisation reaction by reduction, also electrochemically, or by oxidation, obtaining the release of cesium in a solution. As aforesaid, the EAF dusts polluted with 137Cs treatable with the method according to the present invention can have any value of initial radioactivity concentration, either higher or lower than 10,000 Bq/kg. When the dusts to be treated have already undergone a leaching according to the Italian Patent No. 1 358 799, the pre-treated EAF dusts are added with a basifying agent, so as to maintain the same previous alkaline conditions, as well as with a reducing or oxidizing agent. Preferably, the basifying agent is NaHCO3, but other substances suitable for producing basic solutions can also be used. Preferably the reducing agent is Dithionite, the use of which is known for extracting Fe from soils (under the different forms in which it is present) and for reducing chromates. The Dithionite is a sulphide containing oxyanions that, in an aqueous solution, quickly forms two sulphoxyl radicals according to the following reaction a):S2O42−2SO21− a) These radicals cause a reduction of iron (III), also present in the ferrites, from Fe(III) to Fe(II) according to the following reaction b):(Fe3+)2n+nS2O42−(Fe2+)2n+2nSO2 b)allowing the release in a solution of the Cs ions that were captured at the surface of the ferrites. Preferably the oxidizing agent is Potassium Permanganate, which acts in a weakly alkaline solution according to the reaction c):MnO4−+4H++3e−MnO2+2H2O c)or in a strongly alkaline solution according to the reaction d):MnO4−+e−MnO42− d) Simultaneously, the Fe2+ is oxidised to Fe3+. The oxidation reaction could involves also the oxidation of other chemical species that are present, but this is irrelevant for the release of 137Cs. The operative conditions under which the chemical reduction or oxidation reactions take place are: a temperature ranging from 20° C. to 100° C., preferably of 80° C., and a reaction time ranging from 20 minutes and 1.5 hours, preferably of about 1 hour. The higher the temperature, the faster the chemical destabilisation; the reaction time is then also affected by the possible stirring as well as by the dusts particle size (more limited times correspond to a fine particle size; longer times correspond to a coarse particle size). The present embodiment of the invention will be now better described with reference to the examples 1 to 6 below that show the specific effect caused by the reducing agent with respect to the sole leaching treatment. Said examples illustrate a first series of experimental tests in which the dusts samples used, initially treated according to the alkaline leaching with water, had a residual content of 137Cs of about 500 Bq/kg, such as to be refractory to a further leaching. These examples confirm what was previously stated, namely that the method according to the present invention allows to treat EAF dusts polluted with 137Cs having any value of initial radioactivity concentration, either lower or higher than 10,000 Bq/kg, and even very low concentrations, of 500 Bq/kg, as shown below. The reductive attack tests were performed on this sample to verify the possibility of carrying out the chemical destabilisation of the complex Cs-ferrites in order to implement the extractive yield. NaHCO3 was chosen as basifying agent and Dithionite was chosen as reducing agent. An amount of 75 g of polluted dusts already leached according to the Italian Patent No. 1 358 799, with a residual content of 137Cs of about 500 Bq/kg, was suspended in 150 mL of water; then 0.4 g of NaHCO3 and 0.2 g of Dithionite (0.27% by weight) were added. The solution was maintained at a temperature of about 80° C. for 1 hour and then centrifuged. The amount of 137Cs passed in solution, which was found to be 20.9% of the total present in the polluted dust, was determined by radiometric analysis. The same amount of polluted dusts considered in Example 1 was added with an equal amount of NaHCO3 and with 0.3 g of Dithionite (0.40% by weight). Similarly to Example 1, the solution was maintained at a temperature of about 80° C. for 1 hour, and then centrifuged. By the same technique used in Example 1 was therefore determined the amount of 137Cs passed in solution, which was found to be 25.3%. The same amount of polluted dusts considered in Example 1 was added with an equal amount of NaHCO3 and with 0.5 g of Dithionite (0.67% by weight). Similarly to Example 1, the solution was maintained at a temperature of about 80° C. for 1 hour, and then centrifuged. By the same technique used in Example 1 was therefore determined the amount of 137Cs passed in solution, which was found to be 38.6%. The same amount of polluted dusts considered in Example 1 was added with an equal amount of NaHCO3 and with 1.5 g of Dithionite (2% by weight). Similarly to Example 1, the solution was maintained at a temperature of about 80° C. for 1 hour, and then centrifuged. By the same technique used in Example 1 was therefore determined the amount of 137Cs passed in solution, which was found to be 54.5%. The same amount of polluted dusts considered in Example 1 was added with an equal amount of NaHCO3 and with 3 g of Dithionite (4% by weight). Similarly to Example 1, the solution was maintained at a temperature of about 80° C. for 1 hour, and then centrifuged. By the same technique used in Example 1 was therefore determined the amount of 137Cs passed in solution, which was found to be 58.8%. The same amount of polluted dusts considered in Example 1 was added with an equal amount of NaHCO3 and with 7.5 g of Dithionite (10% by weight). Similarly to Example 1, the solution was maintained at a temperature of about 80° C. for 1 hour, and then centrifuged. By the same technique used in Example 1 was therefore determined the amount of 137Cs passed in solution, which was found to be 66.2%. The results are summarised in the following table and graph: %%ExampleDithionite137Cs extracted10.2720.920.4025.330.6738.642.0054.554.0058.8610.0066.2 As it can be seen from the experimental tests carried out, by increasing the Dithionite concentration, a progressive increase of the extraction is obtained; however, it can be noticed that from a Dithionite content of 2% on, a significant slowdown of the extractive yield occurs. These data have been interpreted in terms of release of the 137Cs present in the most superficial part of the ferrites following the reductive destruction of the crystal lattice (by reduction from Fe(III) to Fe(II), as aforesaid). It is therefore evident that the reduction performed by the Dithionite allowed a further decontamination of the starting material, i.e. of the polluted dusts pre-treated by alkaline leaching. In this example the same amount of polluted dusts considered in Example 1 was used, which was added with an equal amount of NaHCO3 and with 1.8 g of KMnO4 (2.4% by weight) in the form of a concentrated solution. Similarly to Example 1, the solution was maintained at a temperature of about 80° C. for 1 hour, and then centrifuged; the final solution had a light violet colour. By the same technique used in Example 1 was therefore determined the amount of 137Cs passed in solution, which was found to be 41.3%. It is therefore evident that also the oxidation (in this case made with KMnO4) allowed a further decontamination of the starting material, i.e. of the polluted dusts already treated by alkaline leaching. This example compares the extraction yield of 137Cs, obtained by treating the same amount of EAF dusts, thoroughly homogenised, through the leaching with water (according to the Italian Patent No. 1 358 799), with the yield achieved through an extraction directly carried out with a solution containing Dithionite as reducing agent (2% by weight with respect to the mass of dust to be extracted). In both cases the temperature of the solutions was the same (80° C.), the pH equal to 12, while the extraction time was 1 hour for both tests. Two comparing tests of the yield were performed under the same conditions: the operations carried out with the solution containing the reducing agent led to extract an amount of 137Cs significantly higher. In the first test a percentage of 48% more than that obtained with the simple leaching was extracted, while in the second test a percentage of 51% more than that obtained with the simple leaching was extracted. This example shows that it is not necessary to operate on dusts pre-treated by leaching, but decontamination can be done, directly and advantageously, with the solution containing the reducing agent. The Inventors believe that, for achieving best results, more drastic conditions should occur, both in terms of concentration of the reducing agent and in terms of reaction time; this tightening of the operating conditions, however, appears to be of little advantage in terms of the process overall yield. Since the destabilisation of the system Cs-ferrites by reduction or by oxidation gave encouraging results, for verification and control further tests were performed, which were focused on alternative approaches to the reduction or the oxidation of the dusts. Method of Reduction in the Pyro-Metallurgical Field The method for removing the 137Cs from polluted EAF dusts according to a second embodiment, in the pyro-metallurgical field, of the present invention comprises the following steps: i) providing an amount of EAF dusts polluted with 137Cs, having an initial average value also >10,000 Bq/kg; ii) subjecting the dusts to a chemical-physical destabilisation reaction by reduction at high temperature; and iii) following the chemical-physical destabilisation reaction by reduction, obtaining the release of cesium. As aforesaid, the EAF dusts polluted with 137Cs treatable with the method according to the present invention can have any value of initial radioactivity concentration, either higher or lower than 10,000 Bq/kg. Typical reducing agents are C, H2 and CH4; the reaction temperature is higher than 800° C., preferably of about 1,000° C. The present embodiment of the invention will be now better described with reference to the examples 9 and 10 below, in which two “dry” systems were used; in particular in the example 9 carbon is used as reducing agent while in the example 10 H2 is used. Also these examples confirm what was previously stated, namely that the method according to the present invention allows to treat EAF dusts polluted with 137Cs having any value of initial radioactivity concentration, either lower or higher than 10,000 Bq/kg, and even very low concentrations, of 500 Bq/kg, as shown below. An amount of 50 g of polluted EAF dusts (500 Bq/kg) was mixed with coal powder (5% by weight) and reacted according to the following reactions e) and f):C+½O2=CO e)Fe3O4+CO=3FeO+CO2 f) The reaction was carried out at about 1,000° C. and proceeded until the formation of Fe(0). The reaction time was approximately 1 hour. The result, in this case, was even more surprising; as a matter of facts, on the treated sample of EAF dusts, the almost total removal of the 137Cs was observed (137Cs content present in the residue <0.5 Bq abs.), while the residue was consisting of Fe(0) and of Al and Si oxides. The 137Cs was extracted at the vapour state together with other volatile elements (Zn, Cd, etc.). In the case of reduction with coal powder, also a microwave heating system has been successfully used. An amount of 50 g of polluted EAF dusts (500 Bq/kg) was subjected to direct reduction in a H2 atmosphere according to the following reaction g):Fe3O4+H2=3FeO+H2O g) The reaction was carried out at about 1,000° C. The reaction time was approximately 1 hour. Also in this case the result was surprising; as a matter of facts, upon exit from the furnace, the almost total removal of the 137Cs from the EAF dusts was observed (137Cs content present in the residue <0.5 Bq abs.), while the residue was consisting of Fe(0) and of Al and Si oxides. The 137Cs was extracted at the vapour state together with other volatile elements (Zn, Cd, etc.). The use of methane as reducing agent in the present embodiment of the invention is not illustrated here by means of a specific example; however, it is based on the following reaction h):CH4+H2O=3H2+CO h) The tests of chemical-physical destabilisation by reduction gave excellent results, since a decontamination between 98% and 100% from the 137Cs initially present in the dusts was achieved. Since the release of cesium at high temperature has occurred by reductive destabilisation of the system as shown by the examples 9 and 10, the Inventors have deemed that, by analogy, also the oxidative destabilisation could be effective to release the 137Cs. Therefore, as a proof, further tests were performed focused on oxidation systems of the dusts. Method of Oxidation in the Pyro-Metallurgical Field The method for removing the 137Cs from polluted EAF dusts according to a third embodiment, in the pyro-metallurgical field, of the present invention comprises the following steps: i) providing an amount of EAF dusts polluted with 137Cs, having an initial average value also >10,000 Bq/kg; ii) subjecting the dusts to a chemical-physical destabilisation reaction by oxidation at high temperature; and iii) following the chemical-physical destabilisation reaction by oxidation, obtaining the release of cesium. As aforesaid, the EAF dusts polluted with 137Cs treatable with the method according to the present invention can have any value of initial radioactivity concentration, either higher or lower than 10,000 Bq/kg. Typical oxidising agents are O2, air and oxygen-enriched air; the reaction temperature is higher than 800° C., preferably of about 1,000° C. The present embodiment of the invention will be now better described with reference to the example 11 below. Also this example confirms what was previously stated, namely that the method according to the present invention allows to treat EAF dusts polluted with 137Cs having any value of initial radioactivity concentration, either lower or higher than 10,000 Bq/kg, and even very low concentrations, of 500 Bq/kg, as shown below. An amount of 50 g of polluted EAF dusts (500 Bq/kg) was subjected to oxidation using, as oxidising agent, oxygen from the air according to the following reaction k):2Fe3O4+O2=3Fe2O3 k) The reaction was carried out at about 1,000° C. The reaction time was approximately 1 hour. In this case the destabilisation of the system Cs-ferrites at high temperature led to the formation of volatile oxides, among which the cesium oxide, and to the formation of a residue consisting of Fe2O3, oxides of some metals and oxides of Al, Si and Ca, with a 137Cs content present in the residue <0.5 Bq abs. Also the tests of chemical-physical destabilisation by oxidation gave excellent results, since a decontamination between 98% and 100% from the 137Cs initially present in the dusts was achieved. In conclusion, the Inventors believe that the experimental tests described above demonstrate that the chemical-physical destabilisation, both reductive and oxidative, of EAF dusts polluted with 137Cs is the key for releasing and recovering the radioactive contaminant. In the hydro-metallurgical field the reaction carried out under mild reducing conditions primarily affects the most superficial layers of the materials that have captured the cesium and allows a reduction of over 60% of the 137Cs recalcitrant to leaching alkaline. It is to be underlined, however, that a preliminary alkaline leaching is clearly neither useful nor necessary, since it is possible to operate directly on the dusts with a reducing solution as demonstrated by the comparative example 8. Moreover, at present, the oxidative hydro-metallurgical treatment appears to be less favourable than the reductive one. The higher yields in terms of decontamination were obtained with both the pyro-metallurgical methods, where the almost complete separation of said 137Cs from said dusts is obtained. It may be noted here that, although these experimental tests have been carried out on certain amounts of EAF dusts having certain contamination levels, the method according to the present invention can be extrapolated to different amounts with different radioactive contamination levels, either higher or lower than 10,000 Bq/kg, on the basis of the reactions reported in the present description. It is also useful to observe that the choice of the optimal method for removing 137Cs from polluted EAF dusts among the different embodiments described above, with reductive and/or oxidative destabilisation (in the hydro- or pyro-metallurgical field) mostly depends on the initial concentration and contamination characteristics of the EAF dust to be treated as well as on the desired final activity (e.g., <380 Bq/kg or <1,000 Bq/kg or <10,000 Bq/kg). By way of example it is reported that, starting from a sample of EAF dusts having an initial contamination value of 218,500 Bq/kg: with the treatment of alkaline leaching with water, a radioactivity reduction to a value of 18,680 Bq/kg was obtained; directly operating with the reductive destabilisation with Dithionite, a radioactivity reduction to a value of 9,285 Bq/kg was obtained; and with the additional oxidative destabilisation (according to Example 11), a radioactivity reduction to a value <380 Bq/kg with an overall yield close to 100% was obtained. With the above example what was previously stated is intended to be confirmed, namely that the method according to the present invention allows to treat EAF dusts polluted with 137Cs having any value of initial radioactivity concentration, either lower or higher than 10,000 Bq/kg, and even at very high concentrations, even >200,000 Bq/kg as now shown. The reduction and/or oxidation reactions can be carried out in traditional plants; the application of these reactions in the method according to the present invention, however, requires specific adjustments. As a matter of facts, the presence of radioactive material involves a number of precautions in terms of safety (specifically: equipment shielding, containment vessels, filters and control systems), which would make it impossible to use “tout court” the conventional plants. Furthermore the recovery of the “off-gases” has, in this case, all the peculiar problems due to the presence of the radioactive material. More precisely, a plant for carrying out the method according to the embodiment in the hydro-metallurgical field of the present invention comprises: a reactor for carrying out the chemical-physical destabilisation reaction of the EAF dusts polluted with 137Cs; a separation and recovery system of the 137Cs from the extraction solution of the EAF dusts; and a recovery system of the decontaminated EAF dusts. For clarity's sake, it is emphasised that said plant is characterised by implementing the method for removing the 137Cs from polluted EAF dusts through a chemical-physical destabilisation reaction in the hydro-metallurgical field by reduction or oxidation. A plant for carrying out the method according to the embodiment in the pyro-metallurgical field of the present invention comprises: a furnace for carrying out the reductive or oxidative chemical-physical destabilisation reaction of the EAF dusts polluted with 137Cs; a separation and recovery system of the 137Cs extracted from the EAF dusts; and a recovery system of the decontaminated EAF dusts. For clarity's sake, it is emphasised that said plant is characterised by implementing the method for removing the 137Cs from polluted EAF dusts through a chemical-physical destabilisation reaction in the pyro-metallurgical field by reduction or oxidation. In the pyro-metallurgical field, the system can be directly fed with the polluted EAF dusts, as described above, but also, in case, with residual dusts coming from a hydro-metallurgical treatment. A plant for carrying out the method according to the embodiment by reductive destabilisation in the pyro-metallurgical field of the present invention for removing the 137Cs contained in polluted EAF dusts, having an average value also >10,000 Bq/kg (but also, in case, with residual dusts coming from a hydro-metallurgical treatment) comprises: a furnace where the dusts mixed with the coal powder (5% by weight) or in a H2 atmosphere are heated; a gas removal system provided with a collection device for both the Cs and the other volatile elements; and a separation system of the Cs from the gas removal aqueous solution; a collection system of the decontaminated reduced dusts with a removal of the activity concentration of the 137Cs between 98% and 100%. Similarly to what was previously described as to the method according to the present invention, the EAF dusts polluted with 137Cs treatable with the aforesaid plant can have any value of initial radioactivity concentration, either higher or lower than 10,000 Bq/kg. Moreover, a plant for carrying out the method according to the embodiment by oxidative destabilisation in the pyro-metallurgical field of the present invention for removing the 137Cs contained in polluted EAF dusts, having an average value also >10,000 Bq/kg (but also, in case, with residual dusts coming from a hydro-metallurgical treatment) comprises: a reactor where the dusts in an oxygen atmosphere or in air are heated; a gas removal system provided with a collection device for the volatile oxides, Cs included; a separation system of the Cs from the gas removal aqueous solution; a collection system of the decontaminated oxidised dusts with a removal of the activity concentration of the 137Cs between 98% and 100%. As aforesaid, the EAF dusts polluted with 137Cs treatable with the aforesaid plant can have any value of initial radioactivity concentration, either higher or lower than 10,000 Bq/kg. In order to obtain EAF dusts decontaminated from 137Cs, the use of the destabilisation reactions takes place according to specific conditions. In particular, the use of the destabilisation reactions according to the present invention provides conditions such as to allow the reduction below 380 Bq/kg of the 137Cs content from EAF dusts contaminated also with an average value also >10,000 Bq/kg. These conditions affect the reducing or oxidising agents used, as well as the temperatures and the reaction times as resulting from the experimental tests mentioned above. While the invention here presented has been illustrated, described and defined with reference to particular preferred embodiments, these references and embodiments given in the above description do not imply any limitation of the invention. It is, however, evident that various modifications and variations can be made without departing from the broader protective scope of the illustrated technical concept. Thus, for example, the Inventors believe that also the electrochemical reduction of the iron oxides, in an alkaline medium, falls within the wider field of the reduction reactions. The illustrated preferred embodiments are merely exemplary and they are not exhaustive of the protective scope of the technical concept here presented. Therefore, the protective scope is not limited to the preferred embodiments described in the detailed description, but is limited only by the claims that follow.
	claims	1. A method for ordered fault clearance visualization and resolution in a computer controlled print production device having a graphical user interface, comprising:receiving data indicating a possible fault event, wherein said data is received from the print production device operational sensors;performing fault analysis to determine whether at least one fault has occurred and to identify the location and fault type for each said fault, wherein said fault type is identified from said data and from fault definitions;prioritizing said identified faults when a plurality of faults are identified, wherein each fault is assigned a unique priority;developing a fault order based on the optimal clearance sequence, wherein said fault order comprises the order in which said prioritized faults are to be cleared;presenting a visualization of the print production device on the graphical user interface, wherein said visualization utilizes graphical cues superimposed upon the visualization of the entire print production device to indicate said fault order, and wherein said visualization further includes a single view of all said identified faults in the system and said fault order in which they are recommended to be cleared;updating said visualization as each said fault is cleared, wherein said updated visualization includes a single view of all remaining identified faults in the system and said fault order in which they are recommended to be cleared;identifying the next said fault among said plurality of faults to be cleared, clearing said fault, and updating said visualization until all of said plurality of faults has been cleared; andupdating said visualization to a no fault state. 2. The method for ordered fault clearance visualization and resolution according to claim 1, wherein said visualization further includes at least one text window providing descriptive messages for each fault presented in said visualization. 3. The method for ordered fault clearance visualization and resolution according to claim 1, wherein said graphical cues include at least one member selected from the group consisting of flashing the object that needs attention, prominent flashing arrows pointing at an area of the printing device, icons, numbers, flashing boxes drawn around the problem area or object, a color change mapped onto the areas of the printing device where the fault is located, and a figurine or character pointing at the problem. 4. The method for ordered fault clearance visualization and resolution according to claim 2, wherein said descriptive message for said cleared fault is removed from said text window when said fault is cleared. 5. The method for ordered fault clearance visualization and resolution according to claim 1, further comprising providing a final notice that no faults remain to be cleared. 6. The method for ordered fault clearance visualization and resolution according to claim 2, wherein said text window displays an ordered listing of said faults based on said optimal clearance sequence. 7. The method for ordered fault clearance visualization and resolution according to claim 1, wherein updating said visualization comprises removing or deemphasizing said graphical cues from said visualization. 8. A system for ordered fault clearance visualization and resolution in a computer controlled print production device having a graphical user interface, comprising:means for receiving data indicating a possible fault event, wherein said data is received from the print production device operational sensors;means for performing fault analysis to determine whether at least one fault has occurred and to identify the location and fault type for each said fault, wherein said fault type is identified from said data and from fault definitions;means for prioritizing said identified faults when a plurality of faults are identified, wherein each fault is assigned a unique priority;means for developing a fault order based on the optimal clearance sequence, wherein said fault order comprises the order in which said prioritized faults are to be cleared;means for presenting a visualization of the print production device on the graphical user interface, wherein said visualization utilizes graphical cues superimposed upon the visualization of the entire print production device to indicate said fault order, and wherein said visualization further includes a single view of all said identified faults in the system and said fault order in which they are recommended to be cleared;means for updating said visualization as each said fault is cleared, wherein said updated visualization includes a single view of all remaining identified faults in the system and said fault order in which they are recommended to be cleared;means for identifying the next said fault among said plurality of faults to be cleared, clearing said fault, and updating said visualization until all of said plurality of faults has been cleared; andmeans for updating said visualization to a no fault state. 9. The system for ordered fault clearance visualization and resolution according to claim 8, wherein said visualization further includes at least one text window providing descriptive messages for each fault presented in said visualization. 10. The system for ordered fault clearance visualization and resolution according to claim 8, wherein said graphical cues include at least one member selected from the group consisting of flashing the object that needs attention, prominent flashing arrows pointing at an area of the printing device, icons, numbers, flashing boxes drawn around the problem area or object, a color change mapped onto the areas of the printing device where the fault is located, and a figurine or character pointing at the problem. 11. The system for ordered fault clearance visualization and resolution according to claim 9, wherein said descriptive message for said cleared fault is removed from said text window when said fault is cleared. 12. The system for ordered fault clearance visualization and resolution according to claim 8, further comprising providing a final notice that no faults remain to be cleared. 13. The system for ordered fault clearance visualization and resolution according to claim 9, wherein said text window displays an ordered listing of said faults based on said optimal clearance sequence. 14. The system for ordered fault clearance visualization and resolution according to claim 8, wherein updating said visualization comprises removing or deemphasizing said graphical cues from said visualization. 15. A computer-readable storage medium having computer readable program code embodied in said medium which, when said program code is executed by a computer causes said computer to perform method steps for ordered fault clearance visualization and resolution, the method comprising:receiving data indicating a possible fault event, wherein said data is received from the print production device operational sensors;performing fault analysis to determine whether at least one fault has occurred and to identify the location and fault type for each said fault, wherein said fault type is identified from said data and from fault definitions;prioritizing said identified faults when a plurality of faults are identified, wherein each fault is assigned a unique priority;developing a fault order based on the optimal clearance sequence, wherein said fault order comprises the order in which said prioritized faults are to be cleared;presenting a visualization of the print production device on the graphical user interface, wherein said visualization utilizes graphical cues superimposed upon the visualization of the entire print production device to indicate said fault order, and wherein said visualization further includes a single view of all said identified faults in the system and said fault order in which they are recommended to be cleared;updating said visualization as each said fault is cleared, wherein said updated visualization includes a single view of all remaining identified faults in the system and said fault order in which they are recommended to be cleared;identifying the next said fault among said plurality of faults to be cleared, clearing said fault, and updating said visualization until all of said plurality of faults has been cleared; andupdating said visualization to a no fault state. 16. The computer-readable storage medium according to claim 15, wherein said visualization further includes at least one text window providing descriptive messages for each fault presented in said visualization. 17. The computer-readable storage medium according to claim 15, wherein said graphical cues include at least one member selected from the group consisting of flashing the object that needs attention, prominent flashing arrows pointing at an area of the printing device, icons, numbers, flashing boxes drawn around the problem area or object, a color change mapped onto the areas of the printing device where the fault is located, and a figurine or character pointing at the problem. 18. The computer-readable storage medium according to claim 16, wherein said descriptive message for said cleared fault is removed from said text window when said fault is cleared. 19. The computer-readable storage medium according to claim 15, further comprising providing a final notice that no faults remain to be cleared. 20. The computer-readable storage medium according to claim 16, wherein said text window displays an ordered listing of said faults based on said optimal clearance sequence. 21. The computer-readable storage medium according to claim is, wherein updating said visualization comprises removing or deemphasizing said graphical cues from said visualization.
	claims	1. A nuclear reactor comprising:a pressure vessel;a reactor core enclosed in the pressure vessel and comprising an array of fuel units;a plurality of regulating control rods located inside the pressure vessel;a regulating control rod drive module comprising a plurality of regulating control rod drive mechanisms enclosed in the pressure vessel;each regulating control rod drive mechanism connected to a corresponding one of the plurality of regulating control rods and configured to move the corresponding regulating control rod relative to the array of fuel units along a longitudinal axis of the corresponding regulating control rod for regulating nuclear reaction at the reactor core during a normal operation of the nuclear reactor;a plurality of shutdown control rods located inside the pressure vessel;a shutdown control rod drive module comprising a plurality of shutdown control rod drive mechanisms enclosed in the pressure vessel; andeach shutdown control rod drive mechanism connected to a corresponding one of the plurality of shutdown control rods and configured to move the corresponding shutdown control rod relative to the array of fuel units parallel to the longitudinal axis for shutting down the nuclear reactor;wherein the reactor core, the regulating control rod drive module and the shutdown control rod drive module are enclosed in the pressure vessel and arranged along the longitudinal axis such that the reactor core is interposed between the regulating control rod drive module and the shutdown control rod drive module,wherein, the regulating and shutdown control rod drive mechanisms are alternately arranged such that, when viewed along the longitudinal axis, a first one of the regulating control rod drive mechanisms is generally surrounded by multiple ones of the shutdown control rod drive mechanisms and further such that, when viewed along the longitudinal axis, each of the multiple shutdown control rod drive mechanisms overlaps with the first regulating control rod drive mechanism,wherein the nuclear reactor is an integral type reactor in which steam generators, a pressurizer, and a reactor coolant pump are provided inside the pressure vessel,wherein when viewed along the longitudinal axis, the steam generators do not overlap with the regulating control rod drive module and the shutdown control rod drive module. 2. The nuclear reactor of claim 1, wherein the regulating control rod drive module is provided above the reactor core, andwherein the shutdown control rod drive module is provided below the reactor core. 3. The nuclear reactor of claim 1, wherein at least one of the plurality of shutdown control rods comprises a lower portion of burnable poison rod. 4. The nuclear reactor of claim 1, wherein the regulating control rod drive module is provided below the reactor core, andwherein the shutdown control rod drive module is provided above the reactor core.
	summary
	description	1. Field of the Invention The present invention relates to a method of controlling the criticality of nuclear fuel cycle facilities, a method of producing uranium dioxide powders (UO2 powders) that are reactor fuels (UO2), a reactor fuel rod loaded in a nuclear reactor, and a fuel assembly. The present invention particularly relates to a method of controlling the criticality of a nuclear fuel cycle facility, such as a fuel fabrication facility or a fresh-fuel storage facility, using a reactor fuel rod fabricated using a UO2 powder containing less than 0.1% by weight of gadolinia (Gd2O3), to a method of producing a UO2 powder, to a reactor fuel rod, and to a fuel assembly. Furthermore, the present invention covers a method of controlling the criticality of a spent-fuel transport/storage cask or a fuel storage pool for storing the fuel assembly. 2. Related Art In order to enhance the power uprating and operation period extension of nuclear power plants and in order to increase the economic efficiency thereof by suppressing the number of spent fuel assemblies in the future, the uranium enrichment of fuel is preferably increased. The increase in the uranium enrichment of fuel reduces the number of fresh fuel assemblies and the number of spent fuel assemblies per unit electricity generated and also greatly reduces fuel cycle costs. Plants for fabricating fuel assemblies for commercial light water reactors are usually designed to pass a safety examination for the criticality safety of fuels with a uranium enrichment of up to 5% by weight. The safety examination is performed according to the guideline “KAKOU SHISETSU NO TAMENO ANZEN SHINSA SHISHIN (Safety Review Guideline for Uranium Processing Facility)”, whereby the construction of such plants is approved. Fuel storage pools and spent-fuel transport/storage casks are evaluated for criticality safety on the basis of the above concept. Reactor fuels with a uranium enrichment of greater than 5% by weight (hereinafter referred to as “over -5% reactor fuels”) are strictly regulated under the guideline “TOKUTEI NO URAN KAKOU SHISETSU NO TAMENO ANZEN SHINSA SHISHIN (Safety Review guideline for Specific Uranium Processing Facility”. In order to use the over -5% reactor fuels, design changes and/or equipment modifications are required for a fabricating step in view of criticality control. Design changes and/or equipment modifications are also required for a fresh-fuel transportation step, a fresh-fuel storage step, a spent-fuel transportation step, and a spent-fuel storage step. This may offset the reduction in fuel cycle costs due to the increase in the enrichment of reactor fuels. For the fuel storage pools and the spent-fuel transport/storage casks, the handling of the following assemblies may be restricted because of criticality control, i.e., fuel assemblies including reactor fuel rods with a uranium enrichment of greater than 5% by weight or existing fuel assemblies with a maximum enrichment of 5% by weight or less. This may require equipment modifications. In order to use the reactor fuels with a uranium enrichment of greater than 5% by weight, such design changes and/or equipment modifications required for each step cause an increase in cost, and therefore, may offset the reduction in fuel cycle costs due to the increase in the enrichment of reactor fuels as described above. Measures need to be taken against this problem. For the use of the reactor fuels with a uranium enrichment of greater than 5% by weight, the upper limit of the uranium enrichment of fuels for commercial light-water reactors is about 10% by weight for practical purposes. The results of the investigation of such measures have shown that equipment modifications are required for steps handling uranium fuels, containing no burnable poison, with an enrichment of greater than 5% by weight in fuel fabrication facilities. For the transportation and storage of fresh and spent fuel assemblies, the modification of transportation casks and transportation equipment may be avoided by making use of the reactivity-suppression effect (gadolinia credit) of a high concentration (several weight percent) of gadolinia, which is a burnable poison widely used for burnable poison-containing fuel assemblies. Upon the implementation of the above measures, the type and concentration of a burnable poison added to reactor fuels are important. Gadolinia, which is a burnable poison widely used for fuel rods for light-water reactors, has a large neutron absorption cross-section and high reactivity-suppression effect. Erbium oxide (Er2O3) and boron (B) have a thermal neutron absorption cross-section less than that of gadolinium (Gd) and are effective in ensuring criticality safety in such a manner that a slight amount of erbium oxide is added to UO2 pellets as disclosed in Patent Document 1, or boron is used to coat the surfaces of UO2 pellets or the inner surfaces of fuel cladding tubes as disclosed in Patent Document 2. As shown in FIGS. 1 to 3, which are disclosed in Non-patent Document 1, Er-167, B-10, and Gd-157, which is an isotope of Gd, have a thermal neutron absorption cross-section of about 640, 3,840, and 254,080 barns, respectively, at room temperature (0.025 eV). That is, the thermal neutron absorption cross-sections of Er-167 and B-10 are far less than that of Gd-157. If a burnable poison is added to a reactor fuel, the burnable poison remains in the reactor fuel at the end of an operation cycle depending on the type of the burnable poison and therefore may cause the reactivity loss of a reactor core. Hence, it is difficult to achieve the reduction in fuel cycle costs due to the increase in the enrichment of reactor fuels. (Prior Art Documents Cited Above) Patent Document 1: Japanese Unexamined Patent Application Publication No. 2004-177241 Patent Document 2: Japanese Unexamined Patent Application Publication No. 4-212093 Non-patent Document 1: Nuclear Data Center at Japan Atomic Energy Agency, JENDL-3.3, [online], retrieved from the internet <URL: http://wwwndc.tokai-sc.jaea.go.jp/jendl/j33/J33_J.html> Non-patent Document 2: Nuclear Materials Regulation Division/Nuclear Safety Bureau/Science and Technology Agency, “Nuclear Criticality Safety Handbook”, Nikkan-shobou, 1988 Non-patent Document 3: Thermal and Nuclear Power Engineering Society, “Atomic Fuel Cycle and Disposal Treatment”, 1986 The present invention has been made in consideration of the circumstances encountered in the prior art mentioned above, and an object of the present invention is a method of controlling criticality of a nuclear fuel cycle facility and a method of producing uranium dioxide powder for the purpose of reducing an impact on the criticality control of a nuclear fuel cycle facility by adding a slight amount of gadolinia, which is a burnable poison with a large neutron absorption cross-section, to a reactor fuel with a uranium enrichment of greater than 5% by weight and to increase economic efficiency by making use of the reduction in fuel cycle costs due to the increase in the enrichment of the reactor fuel. In the criticality control of fuel storage pools and spent-fuel transport/storage casks, the handling of the following assemblies may be restricted; that is: fuel assemblies including reactor fuel rods with a uranium enrichment of greater than 5% by weight or fuel assemblies with a uranium enrichment of 5% by weight or less or a uranium enrichment close to 5% by weight among fuel assemblies containing a reactor fuel with a maximum uranium enrichment of 5% by weight or less. It is an object of the present invention to reduce the impact on the criticality control of a fuel storage pool and a spent-fuel transport/storage cask, in consideration that a reactor fuel rod containing a high or slight amount of gadolinia is processed in a fuel fabrication step. The above and other objects can be achieved according to the present invention by providing, in one aspect, a method of controlling the criticality of a nuclear fuel cycle facility, comprising the steps of: producing a reactor fuel by adding less than 0.1% by weight of gadolinia to n uranium dioxide powder with a uranium enrichment of greater than 5% by weight; and controlling the effective neutron multiplication factor of a uranium dioxide system in a step of handling the reactor fuel to be less than or equal to maximum of an effective neutron multiplication factor of the uranium dioxide system with a uranium enrichment of 5% by weight. In the above aspect, the method may further include the step of setting an amount of gadolinia added to the uranium dioxide powder with a uranium enrichment of greater than 5% by weight such that the maximum of the effective neutron multiplication factor of the uranium dioxide powder with a uranium enrichment of greater than 5% by weight is less than or equal to that of the uranium dioxide powder with a uranium enrichment of 5% by weight, in the maximums of effective neutron multiplication factors specified by constraints for ensuring the subcriticality of mass control not handling any fuel having a mass exceeding a predetermined value relating to criticality safety design or geometry control not handling any fuel having a size exceeding a predetermined value relating to criticality safety design over the entire range of uranium concentration under such complete submergence conditions that spaces between particles of the uranium dioxide powder with a uranium enrichment of 5% by weight are filled with water and the particles are surrounded by water for a fuel fabrication facility. It may be further desired that the uranium dioxide powder with a uranium enrichment of greater than 5% by weight has a uranium enrichment of up to 10% by weight and the content of gadolinia in the reactor fuel is within a range from 305 to 915 ppm. In this regard, an amount of gadolinia added to the uranium dioxide powder with a uranium enrichment of greater than 5% by weight is proportional to the uranium enrichment thereof that exceeds 5% and the constant of the proportion is determined by dividing the amount of gadolinia added to a uranium dioxide powder with a uranium enrichment of 10% by weight by five. In another aspect of the present invention, there is also provided a method of producing a uranium dioxide powder comprising the steps of: reconverting uranium hexafluoride; and adding an aqueous solution of gadolinium nitride to a uranium solution treated in a reconverting step so as to produce a uranium dioxide powder which contains less than 0.1% by weight of gadolinia and which has a uranium enrichment of greater than 5% by weight. In a further aspect of the present invention, there is also provided a method of producing a uranium dioxide powder comprising the steps of: preparing a first powder mixture by adding about 1% to 10% by weight of gadolinia to a uranium dioxide powder with a uranium enrichment of greater than 5% by weight; and preparing a powder mixture by adding the uranium dioxide powder with a uranium enrichment of greater than 5% by weight to the first powder mixture in several stages so as to produce a uranium dioxide powder which contains less than 0.1% by weight of gadolinia and which has a uranium enrichment of greater than 5% by weight. In a still further aspect of the present invention, there is also provided a reactor fuel rod comprising: a cylindrical fuel cladding tube including a lower-end plug welded to the lower end thereof; cylindrical fuel pellets packed in the fuel cladding tube; a plenum spring, placed in an upper hollow portion of the fuel cladding tube, for elastically pressing the fuel pellets; and an upper-end plug welded to the lower end of the fuel cladding tube, wherein the fuel pellets are formed from a uranium dioxide powder which contains less than 0.1% by weight of gadolinia and which has a uranium enrichment of greater than 5% by weight. In a still further aspect of the present invention, there is also provided a fuel assembly for a light-water reactor comprising: a first reactor fuel rod, having a gadolinia content of 0.1% by weight or more, for controlling reactivity and power distribution of a reactor core in operation; and a second reactor fuel rod, of the type mentioned above, which contains fuel pellets formed from a uranium dioxide powder, containing less than 0.1% by weight of gadolinia, having a uranium enrichment of greater than 5% by weight and which has same configuration as that of a reactor fuel rod. The fuel assembly may further include a third reactor fuel rod with a uranium enrichment of 5% by weight or less. In a still further aspect of the present invention, there is also provided a method of controlling the criticality of a nuclear fuel cycle facility, comprising: controlling the criticality of a fuel storage pool or a spent-fuel transport/storage cask for storing the fuel assembly mentioned above or a fuel assembly which includes only the third reactor fuel rod mentioned above and which has a gadolinia content of 0.1% by weight or more, wherein the subcriticality of the fuel storage pool or the spent-fuel transport/storage cask is ensured in such a manner that the effective neutron multiplication factor of the fuel assembly is assumed to be the maximum effective neutron multiplication factor of a reactor fuel over the entire period of the burning of the reactor fuel. According to the present invention, a slight amount of gadolinia, which is a burnable poison having a large neutron absorption cross-section, is uniformly added to a reactor fuel with a uranium enrichment of greater than 5% by weight, whereby influences on measures for controlling the criticality of a nuclear fuel cycle facility can be reduced. Furthermore, economic efficiency can be increased by making use of the reduction in fuel cycle costs due to the increase in the enrichment of the reactor fuel. In the case where there are constraints on criticality control when a fuel assembly is handled in a fuel storage pool or a spent-fuel transport/storage cask, influences on measures for criticality control can be reduced in consideration that a reactor fuel rod containing a slight or large amount of gadolinia is treated in a fuel fabrication step. The nature and further characteristic features of the present invention will be made clearer from the following descriptions made with reference to the accompanying drawings. Embodiments of the present invention will be described hereunder with reference to the accompanying drawings. The term “reactor fuel” used herein covers powders containing UO2 particles, fuel pellets made from the powders, reactor fuel rods including the fuel pellets, bundles of the reactor fuel rods, and fuel assemblies including the bundles. The term “uranium oxide system (UO2 system)” used herein means a system in which spaces between powders including partially or entirely UO2 particles, fuel pellets made from a powder containing the UO2 particles, arrangement of such fuel pellets, reactor fuel rods including the fuel pellets, bundles of the reactor fuel rods, and fuel assemblies including the bundles are filled water, and in which the UO2 particles, the fuel pellets, the reactor fuel rods, the bundles, and the fuel assemblies are surrounded by water under given conditions of predetermined size and mass. In descriptions below, 1 ppm is equal to 1×10−4 weight percent. A reactor fuel containing less than 0.1% by weight of gadolinia is hereinafter referred to as a low-gadolinia content fuel. A reactor fuel containing 0.1% by weight or more of gadolinia is hereinafter referred to as a high-gadolinia content fuel. [First Embodiment] A method of controlling the criticality of a nuclear fuel cycle facility according to a first embodiment of the present invention will now be described with reference to FIGS. 4 and 5. Non-patent Document 2 specifies “minimum estimated criticality values” and “minimum estimated criticality lower-limits” that are constraints used in “mass control” not handling any reactor fuel having a mass exceeding a limit on criticality control or “geometry control” not handling any reactor fuel having a size exceeding a limit on criticality control with respect to a uniform UO2-H2O system that is the strictest model on criticality control in consideration of “complete submergence”. Table 1 shows constraints used in a UO2 powder-handling step (hereinafter referred to as a UO2 powder step). The term “estimated criticality value” used herein means such a value that something having a mass or size equal to the value is determined to be critical. The term “estimated criticality lower-limit” used herein means such a value that something having a mass or size less than or equal to the value is determined to be subcritical. Values shown in Table 1 are minimum values over the entire range of the concentration of uranium. TABLE 1Minimum estimatedMinimum estimatedcriticality valuescriticality lower-limitsEnrichment (weight percent)34510203451020Diameter of—38.225.720.317.9—26.924.419.417.2infinitecylinders (cm)Thickness of—13.411.98.426.87—12.711.27.976.20infiniteplates (cm)Volume of45.432.927.415.710.840.129.424.014.19.62spheres (L)Mass (kgU)92.153.936.7——79.645.633.0—— The method of this embodiment is as follows: a slight amount, for example, less than 0.1% by weight of gadolinia is uniformly added to a UO2 powder, handled in fuel fabrication facilities, having a uranium enrichment of greater than 5% by weight, whereby the effective neutron multiplication factor of the mixture is controlled to be less than or equal to the maximum of an effective neutron multiplication factor which is a constraint on mass or geometry control for controlling the criticality safety of a UO2 powder with a uranium enrichment of 5% by weight. That is, a slight amount of gadolinia is added to the UO2 powder with a uranium enrichment of greater than 5% by weight such that an effective neutron multiplication factor for the mass or geometry control of the UO2 powder with a uranium enrichment of greater than 5% by weight is controlled to be less than or equal to the maximum of an effective neutron multiplication factor for the mass or geometry control for a UO2 powder, shown in Table 1, having a uranium enrichment of 5% by weight. Thus, a constraint on the criticality safety of the UO2 powder with a uranium enrichment of greater than 5% by weight is controlled to be equal to a constraint on the criticality safety of the UO2 powder with a uranium enrichment of 5% by weight. The term “a uranium enrichment of 5% by weight” used herein covers a range from 4.5% to 5.0% by weight. A UO2 powder with a uranium enrichment of 3% by weight and a UO2 powder with a uranium enrichment of 4% by weight, which are shown in Table 1, are included in this embodiment in addition to the UO2 powder with a uranium enrichment of 5% by weight which is a reference for comparison. Constraints on the UO2 powders with a uranium enrichment of 3% or 4% by weight are severe, and therefore, the amount of gadolinia added thereto becomes large. Table 1 shows the UO2 powders with a uranium enrichment of 3%, 4%, or 5% and UO2 powders with a uranium enrichment of 10% or 20% by weight. FIG. 4 is a graph showing the content of gadolinia relating to the mass control of 33 kgU of the UO2 powder with a uranium enrichment of 5% by weight. With reference to FIG. 4, Line “A” represents the maximum of the effective neutron multiplication factor of the UO2 powder with a uranium enrichment of 5% by weight, the effective neutron multiplication factor giving a mass of 33 kgU at the minimum estimated critical lower-limit of the UO2 powder with a uranium enrichment of 5% by weight over the entire range of the content of uranium. FIG. 4 gives the relationship between the content of gadolinia and the enrichment of uranium that is determined such that the effective neutron multiplication factors of UO2 powders, containing a slight amount of gadolinia, with a uranium enrichment of greater than 5% by weight are less than or equal to the maximum represented by Line “A”. The relationship between the content of gadolinia and the enrichment of uranium is given by a neutron transport calculation performed for a water-reflected spherical system in which spaces between particles of a UO2 powder are filled with water using the content of gadolinia (or the volume of the spherical system) as a parameter. The following results are then obtained; that is: the amount of gadolinia added to each UO2 powder with a uranium enrichment of 6%, 7%, 8%, or 10% by weight is 53, 110, 170, or 305 ppm, respectively. According to neutron transport calculations performed for an infinite cylinder with a diameter of 24.4 cm, an infinite plate with a thickness of 11.2 cm, and a sphere with a radius of 24.0 cm under the same gadolinia content condition using the content of gadolinia as a parameter, the infinite cylinder, the infinite plate, and the sphere being made of the UO2 powder with a uranium enrichment of 5% by weight, the effective neutron multiplication factors of the UO2 powders, containing a slight amount of gadolinia, with a uranium enrichment of greater than 5% by weight are less than the maximum of the effective neutron multiplication factor of the UO2 powder with a uranium enrichment of 5% by weight and constraint conditions are satisfied. In a fuel fabrication facility, neutron transport calculations are performed for a step of forming fuel pellets, step of fabricating a reactor fuel rod, and step of fabricating a fuel assembly subsequent to a step of producing a UO2 powder under the same gadolinia content condition, and it is thereby confirmed that the effective neutron multiplication factor of the UO2 powder-producing step is minimum. That is, by using a gadolinia content set in the UO2 powder-producing step, the effective neutron multiplication factor of a UO2 system concerning an array of fuel pellets containing a reactor fuel with a uranium enrichment of greater than 5% by weight, a bundle of reactor fuel rods, or a fuel assembly is restricted to be less than or equal to the effective neutron multiplication factor of a fuel pellet, reactor fuel rod, or fuel assembly with a uranium enrichment of 5% by weight. Likely, the constraint conditions are satisfied. FIG. 5 is a graph showing the relationship between the amount of gadolinia added to the UO2 powders with a uranium enrichment of greater than 5% by weight and the uranium enrichment of these UO2 powders. The amount of gadolinia added to the UO2 powder with a uranium enrichment of 5% by weight is 0 ppm. The amount of gadolinia added to the UO2 powder with a uranium enrichment of 10% by weight is 305 ppm. The term “a uranium enrichment of 10% by weight” used herein covers a range from 9.5% to 10.0% by weight. As shown in FIG. 5, the amount of gadolinia added to the UO2 powders with a uranium enrichment of greater than 5% by weight is substantially proportional to the uranium enrichment of these UO2 powders. Supposing that the uranium enrichment and the gadolinia content are limited to 10% by weight or less and 305 ppm or less, respectively, and are in proportion to each other, the gadolinia content can be readily determined by using a proportional constant of, for example, 61, the proportional constant being obtained by dividing the gadolinia content (305 ppm) of the UO2 powder with a uranium enrichment of 10% by weight by 5. In view of criticality control, a control technique using this approximate straight line is more safe than a technique in which the content of gadolinia is calculated from the enrichment of uranium, because the content of gadolinia is determined to be relatively large. In this embodiment, a number by which the gadolinia content (305 ppm) of the UO2 powder with a uranium enrichment of 10% by weight is divided ranges from 4.5 to 5.5 because the lower limit and upper limit of the uranium enrichment range from 4.5% to 5.0% by weight and from 9.5% to 10.0% by weight, respectively. According to this embodiment, as for the criticality control, a reactor fuel with a uranium enrichment of greater than 5% by weight can be treated on equal terms with a UO2 powder with a uranium enrichment of 5% by weight by uniformly adding a slight amount of gadolinia to a UO2 powder for fabricating the reactor fuel. Therefore, in a fuel fabrication facility, fabrication steps such as a step of handling a UO2 powder, a step of forming fuel pellets, a step of fabricating a reactor fuel rod, a step of fabricating a fuel assembly, and a step of storing the fuel assembly can be controlled in the criticality control on equal terms with a step of handling the reactor fuel with a uranium enrichment of 5% by weight. In fuel cycle steps including a fresh-fuel transport step, a fresh-fuel storage step, a spent-fuel storage step, and a spent-fuel transport step in addition to a fuel fabrication step, the effective neutron multiplication factors of a fuel storage pool and a spent-fuel transport/storage cask are held to be less than a constraint for ensuring subcriticality by making use of the reactivity-suppression effect of gadolinia, whereby cost increases due to design changes or equipment modifications can be prevented and fabrication costs can be prevented from being increased. [Second Embodiment] A method of producing a UO2 powder according to a second embodiment of the present invention will be described hereunder with reference to FIGS. 6 to 8. In order to produce a reactor fuel from the UO2 powder, a burnable poison is uniformly added to the UO2 powder. Therefore, the reactivity-suppression effect of the burnable poison can be used in a step of handling the UO2 powder. FIG. 6 is a flowchart showing a conventional method of producing a UO2 powder through the reconversion of uranium hexafluoride (UF6) by a solvent extraction process. As shown in FIG. 6, UF6 is added to an aqueous solution of aluminum nitrate, an aqueous solution of uranyl nitrate is thereby prepared. Ammonia is added to the aqueous uranyl nitrate solution, ammonium diuranate (ADU) is thereby precipitated, and the obtained precipitate is dehydrated, roasted, and then reduced, thus producing the conventional UO2 powder. FIG. 7 is a flowchart showing the method of this embodiment. In the method, a slight amount of an aqueous solution of gadolinium nitrate is used in the process of producing the UO2 powder through the reconversion of UF6 by a solvent extraction process such that a uniform powder mixture of gadolinia and UO2 is obtained. According to the method of this embodiment, as shown in FIG. 7, a slight amount of the aqueous gadolinium nitrate solution is added to an aqueous solution of uranyl nitrate obtained by a solvent extraction process, and a uniform solution is then prepared. A uniform powder mixture containing UO2 and a slight amount of gadolinia is produced from ammonium diuranate (ADU) containing gadolinia. Since the uniform solution is prepared by adding a slight amount of the aqueous gadolinium nitrate solution to the aqueous uranyl nitrate solution, gadolinia and UO2 are uniformly mixed together in the UO2 powder. A wet ADU process and the like are examples of a process of producing another UO2 powder. The wet ADU process may include a step of preparing an aqueous solution of uranyl nitrate and a step of adding an aqueous solution of gadolinium nitrate to this aqueous uranyl nitrate solution. This allows a UO2 powder in which UO2 and a slight amount of gadolinia are uniformly mixed together to be produced. Alternatively, as shown in FIG. 8, after a UO2 powder is received, a first powder mixture is prepared by uniformly mixing the UO2 powder and a gadolinium powder together so as to have a gadolinium content of about 1% to 10% by weight. A second powder mixture is prepared by uniformly mixing the first powder mixture and the received UO2 powder together such that the content of the first powder mixture in the second powder mixture is about 1% to 10% by weight. A third powder mixture is prepared by uniformly mixing the second powder mixture and the UO2 powder together such that the content of the second powder mixture in the third powder mixture is about 1% to 10% by weight. This allows the third powder mixture to have a gadolinia content of about 0.1% by weight or less. That is, a burnable poison-containing powder mixture in which the gadolinia powder and the UO2 powder are uniformly mixed and which has a gadolinia powder content of less than 0.1% by weight can be produced by repeating the step of mixing or diluting the gadolinia powder with an about tenfold amount of the UO2 powder several times. [Third Embodiment] A reactor fuel rod according to a third embodiment of the present invention will be described hereunder with reference to FIG. 9. FIG. 9 is a schematic sectional view of the reactor fuel rod 1. The reactor fuel rod 1 includes a cylindrical fuel cladding tube 2 including: a lower-end plug 3 welded to the lower end thereof; cylindrical fuel pellets 4 which are packed in the fuel cladding tube 2 and which are made from a UO2 powder containing a slight amount of gadolinia; a plenum spring 5, placed in an upper hollow portion of the fuel cladding tube 2, for pressing the fuel pellets 4; and an upper-end plug 6 welded to the lower end of the fuel cladding tube 2. The UO2 powder contains, for example, less than 0.1% by weight of gadolinia. The fuel pellets 4 are produced by sintering the UO2 powder. In particular, the UO2 powder is pressed into blanks with a predetermined shape. The blanks are heat-treated in a reducing atmosphere so as to be sintered, to thereby obtain the fuel pellets 4. The fuel pellets 4 have high density and high mechanical strength and are chemically stable. The fuel pellets 4 are ground so as to have a predetermined size. The fuel pellets 4 can be produced by a known process. According to this embodiment, as for criticality control, fuel pellets and reactor fuel rods with a uranium enrichment of greater than 5% by weight can be treated on equal terms with a reactor fuel with a uranium enrichment of 5% by weight or less. That is, a UO2 powder with a gadolinia content of less than 0.1% by weight can be processed into a reactor fuel by a process similar to a process for fabricating a conventional reactor fuel rod, and hence, a reactor fuel rod with a uranium enrichment of greater than 5% by weight can be fabricated without modifying a fuel-processing facility. [Fourth Embodiment] A fuel assembly, according to a fourth embodiment of the present invention, for light-water reactors will be described hereunder with reference to FIGS. 10 to 13. FIG. 10 is an illustration showing the two-dimensional arrangement pattern of a design example of a conventional replacement fuel assembly (used for two-year operation-cycle, having an average burnup of about 70 GWd/t), having an average uranium enrichment of about 6.2% by weight, for boiling-water reactors and also showing that of a replacement fuel assembly including reactor fuel rods 1 fabricated using UO2 powders which slightly contain, for example, less than 0.1% by weight of gadolinia and which have a uranium enrichment of greater than 5% by weight. The fuel assembly of this embodiment includes reactor fuel rods fabricated using UO2 powders which slightly contain, for example, less than 0.1% by weight of gadolinia and which have a uranium enrichment of greater than 5% by weight. These reactor fuel rods are classified into three types: reactor fuel rods fabricated using a UO2 powder which contains, for example, 53 ppm gadolinia and which has a uranium enrichment of 6% by weight; reactor fuel rods fabricated using a UO2 powder which contains, for example, 110 ppm gadolinia and which has a uranium enrichment of 7% by weight; and reactor fuel rods fabricated using a UO2 powder which contains, for example, 170 ppm gadolinia and which has a uranium enrichment of 8% by weight. FIG. 11 shows the infinite multiplication factor of a design example of a conventional replacement fuel assembly, having an average uranium enrichment of about 6.2% by weight, for boiling-water reactors and also shows that of a replacement fuel assembly including reactor fuel rods fabricated using a UO2 powder which slightly contains, for example, less than 0.1% by weight of gadolinia and which has a uranium enrichment of greater than 5% by weight, the replacement fuel assemblies being under operation (a void fraction of 40%). With reference to FIG. 11, Line “B” represents the relationship between the infinite multiplication factor and burnup of the fuel assembly of this embodiment. Line “C” represents the relationship between the infinite multiplication factor and burnup of a fuel assembly including reactor fuel rods fabricated using UO2 powders which have a uranium enrichment of greater than 5% by weight and a gadolinia content that is about two times greater than that of the UO2 powders used to fabricate the reactor fuel rods included in the fuel assembly of this embodiment. The fuel assembly represented by the Line “C” includes: reactor fuel rods fabricated using a UO2 powder having a gadolinia content of 106 ppm and a uranium enrichment of 6% by weight, reactor fuel rods fabricated using a UO2 powder having a gadolinia content of 220 ppm and a uranium enrichment of 7% by weight; and reactor fuel rods fabricated using a UO2 powder having a gadolinia content of 340 ppm and a uranium enrichment of 8% by weight. Line “D” represents the relationship between the infinite multiplication factor and burnup of a fuel assembly including reactor fuel rods fabricated using UO2 powders which have a uranium enrichment of greater than 5% by weight and a gadolinia content that is about three times greater than that of the UO2 powders used to fabricate the reactor fuel rods included in the fuel assembly of this embodiment. The fuel assembly represented by the Line “D” includes: reactor fuel rods fabricated using a UO2 powder having a gadolinia content of 159 ppm and a uranium enrichment of 6% by weight; reactor fuel rods fabricated using a UO2 powder having a gadolinia content of 330 ppm and a uranium enrichment of 7% by weight; and reactor fuel rods fabricated using a UO2 powder having a gadolinia content of 510 ppm and a uranium enrichment of 8% by weight. As shown in FIG. 11, the difference between the infinite multiplication factor of the conventional fuel assembly and that of each fuel assembly represented by the Line “B”, “C” or “D” is small, that is, about 1% to 3% Δk in an initial stage of burning, and hence, the influence on the reactivity of a reactor core is slight. The fuel assembly of this embodiment has a difference in infinite multiplication factor of about 1% Δk, and hence, a conventional design need not be modified. The fuel assemblies including the reactor fuel rods fabricated using the UO2 powders having a uranium enrichment of greater than 5% by weight and a gadolinia content that is about two or three times greater than that of the UO2 powders used to fabricate the reactor fuel rods included in the fuel assembly of this embodiment have a small difference in infinite multiplication factor of about 2% and 3% Δk, respectively. Accordingly, a conventional design need not be modified or needs to be slightly changed in the number of reactor fuel rods with a high gadolinia content, the gadolinia content thereof, or the arrangement of the reactor fuel rods. The difference between the infinite multiplication factor of the conventional fuel assembly and that of the fuel assembly of this embodiment decreases with the progress of burning and disappears at a cycle burnup of about 5 GWd/t or more (corresponding to half-year operation). Therefore, the reactivity loss caused by gadolinia in a final stage of an operation cycle is negligible. A UO2 powder with a uranium enrichment of 10% by weight may have a gadolinia content of up to 915 ppm, which is three times greater than the gadolinia content (305 ppm) of the UO2 powder, described in the first embodiment, having a uranium enrichment of 10% by weight. UO2 powders with a uranium enrichment of greater than 5% by weight may have a gadolinia content that is up to three times greater than those described in the first embodiment. The content of gadolinia can be determined in a hatched region sandwiched between Lines “E” and “F” in FIG. 12. The content of gadolinia in a reactor fuel with a uranium enrichment of greater than 5% by weight is less than about 0.1% by weight. According to this embodiment, as for the criticality control, a fuel assembly with a uranium enrichment of greater than 5% by weight can be treated on equal terms with a reactor fuel with a uranium enrichment of 5% by weight or less. That is, a reactor fuel rod can be fabricated by a process, similar to a process for fabricating a conventional reactor fuel rod, using a UO2 powder having a gadolinia content of, for example, less than 0.1% by weight and a uranium enrichment of 5% by weight or more. Accordingly, a fuel assembly with a uranium enrichment of greater than 5% by weight can be obtained with no equipment modifications. Gadolinia, which is slightly contained in a fuel assembly, rapidly burns out in an initial stage of burning and therefore causes no reactivity loss in a final stage of an operation cycle. Hence, gadolinia can meet an increase in economic efficiency due to the use of reactor fuels with a uranium enrichment of greater than 5% by weight. The fuel assembly of this embodiment can be used for boiling-water reactors including reactor fuel rods having different uranium enrichments as described above and can be used for pressurized-water reactors including reactor fuel rods having a single uranium enrichment. FIG. 13 is an illustration showing reactor fuel rods arranged in a fuel assembly for pressurized-water reactors. The reactor fuel rods have a uranium enrichment of greater than 5% by weight and contain a slight amount of gadolinia. This fuel assembly is a modification of the fuel assembly of this embodiment. Another modification of the fuel assembly of this embodiment may include reactor fuel rods, having a uranium enrichment of 5% by weight or less, placed in corner and/or peripheral portions thereof so as to provide a uniform power distribution. The fuel assembly of this embodiment may contain borosilicate glass or another material serving as a burnable poison. The fuel assembly of this embodiment has only a slight influence on the initial reactivity of a reactor core and no unburned portion of gadolinia remains in reactor fuel rods arranged in the fuel assembly of this embodiment in a final stage of an operation cycle, thereby preventing reactivity loss. Therefore, the number of fresh fuel rods for replacement and fuel cycle costs can be greatly reduced by increasing the enrichment of reactor fuels, which is the purpose of using reactor fuels with a uranium enrichment of greater than 5%. [Fifth Embodiment] A method, according to a fifth embodiment of the present invention, for controlling the criticality of a nuclear fuel cycle facility will be described hereunder with reference to FIGS. 14 and 15. In the case of handling fuel assemblies including reactor fuel rods with a uranium enrichment of greater than 5% by weight or handling fuel assemblies which have a maximum uranium enrichment of 5% by weight or less and which include reactor fuel rods with an average uranium enrichment of 4.5% to 5% by weight, there may be some constrains on fuel storage pools and spent-fuel transport/storage casks because effective neutron multiplication factors have been used to control criticality without any regard for the reactivity-suppression effect of unburned gadolinia. According to the method of this embodiment, a reactor fuel having the largest effective neutron multiplication factor over the entire period of burning is supposed in consideration that a reactor fuel rod containing a slight amount, for example, less than 0.1% by weight of gadolinia or a large amount of gadolinia is treated in a fuel fabrication step. Accordingly, the subcriticality of the fuel storage pools and spent-fuel transport/storage casks, which are used to store the fuel assemblies, is ensured such that influences on measures on criticality control are reduced. FIG. 14 is a graph showing the relationship between the infinite neutron multiplication factor and burnup of a system including fuel assemblies infinitely arranged at low temperature, the system being an example of a reactor fuel, including reactor fuel rods with high gadolinia content, for boiling-water reactors. The maximum infinite neutron multiplication factor k1 of the reactor fuel containing gadolinia is less than the infinite neutron multiplication factor k0 of a reactor fuel containing no gadolinia. FIG. 15 is a graph showing the relationship between the infinite neutron multiplication factor and burnup of a reactor fuel, having a gadolinia content of 100 ppm, for pressurized-water reactors at low temperature. The maximum infinite neutron multiplication factor k1 of the reactor fuel containing gadolinia is less than the infinite neutron multiplication factor k0 of a reactor fuel containing no gadolinia. That is, the reactivity of a reactor fuel can be reduced by adding a large or slight amount of gadolinia to this reactor fuel. Therefore, the maximum infinite neutron multiplication factor k1 of a fuel assembly containing this reactor fuel over the entire period of burning can be used instead of the infinite neutron multiplication factor k0 of the fuel assembly that has been conventionally determined without any regard for the reactivity-reducing effect of unburned gadolinia. This allows the effective neutron multiplication factor of a fuel storage pool and spent-fuel transport/storage cask for storing the fuel assembly to be reduced, thereby ensuring the subcriticality of the fuel storage pool and the spent-fuel transport/storage cask. In this embodiment, gadolinia, which is a rare-earth oxide, is used as a burnable poison. Samarium oxide, which has a large neutron absorption cross-section, may be used instead of gadolinia. In the case where there are constraints on criticality control when a fuel assembly is handled in a fuel storage pool or a spent-fuel transport/storage cask, the method of this embodiment can be used even if the fuel assembly has a uranium enrichment of 5% by weight or less. That is, in the case where there are constraints on criticality control when the fuel assembly is stored, the use of the method of this embodiment is effective in preventing an increase in cost due to modifications such as design modifications and/or equipment modifications because the method of this embodiment assumes the fuel assembly as a reactor fuel having a maximum effective neutron multiplication factor over the entire period of burning. According to the above embodiments, a slight amount of gadolinia is uniformly added to a UO2 powder for producing a reactor fuel with a uranium enrichment of greater than 5% by weight. Therefore, costs, relating to criticality safety, for modifying fuel fabrication facilities and fabrication costs can be prevented from being increased. Furthermore, no unburned portion of gadolinia remains in a final stage of an operation cycle, and therefore, no reactivity loss is caused. The number of fresh fuel rods for replacement can be reduced because of an increase in the enrichment of a reactor fuel, and hence, economic efficiency can be increased. When there may be constraints on the criticality control of not only reactor fuels with a uranium enrichment of greater than 5% by weight but also current fuel assemblies including fuel rods with a maximum enrichment of 5% by weight or less, influences on measures for ensuring the subcriticality of fuel storage pools and spent-fuel transport/storage casks can be reduced in such a manner that the reactor fuels are assumed as reactor fuels having the maximum reactivity over the entire period of burning in consideration that reactor fuel rods containing a slight or large amount of gadolinia are treated in a fuel fabrication step. It is further to be noted that the present invention is not limited to the described embodiments and many other changes and modifications may be made without departing from the scope of the appended claims.
	description	This application is a continuation-in-part of U.S. patent application Ser. No. 10/128,678 filed on Apr. 23, 2002, which is now abandoned. 1. Field of the Invention The invention generally relates to baseball and, more particularly, to a statistical method for evaluating the performance of a relief pitcher. 2. Description of the Prior Art Baseball thrives, and in large measure survives, by its ability to evaluate, differentiate and classify its product—namely, its players and teams. This is true for hitters, for pitchers, and, to a lesser extent, for position players in the field. Who had the best season at the plate? Generally speaking, the batting average tells us. Who had the most productive season? Perhaps it's the slugging percentage or the Runs Batted In (RBI) that tells us. Or is it the statistic that indicates which player crossed home plate the most times (Runs Scored)? Or perhaps the statistic that states who had the best on-base average, or the most walks, or the most hits. Measuring pitching performance has also been one of the most common subjects of statistics, and can be found in newspapers from the 1800s. Which pitcher won how many games? The won/loss columns tell us. This is the most widely used measure of a pitcher's worth. Which pitcher struck out the most batters? Which pitcher yielded the fewest walks? Which pitcher allowed the fewest hits? Which pitcher allowed the fewest batters to cross home plate due to his mistakes (the Earned Run Average, or “ERA”)? This is the second most widely used measure of a pitcher's worth, after the total amount of “wins.” Which pitcher had the most “saves,” so to speak, out of the bullpen? A “save” is credited to a relief (or “substitute”) pitcher when the pitcher who starts the game is removed from the game while his team is in the lead; the relief pitcher holds the opposite team in check so that his team remains ahead and goes on to win the game. (It has been said that the “blown save” is baseball's most “deflating moment, and its most haunting,” The New York Times, Mar. 31, 2002, Sect. 8a, p. 3.) The following is a more specific definition of a “save” in pitching: A pitcher can earn a save by completing all three of the following terms: (1) Finishes the game won by his team; (2) Does not receive the win; (3) Meets one of the following three items: (a) Enters the game with a lead of no more than three runs and pitches at least one inning; (b) Enters the game with the tying run either on base, at bat or on deck; and/or (c) Pitches effectively for at least three innings. The number of “saves” has been used for years as a measure of the value of a relief pitcher. Baseball is not immune to society's rush into specialization. Just as a general practitioner M.D. recommends a patient to a specialist, and an attorney might specialize in maritime law, baseball is becoming more and more specialized as to how it uses its players. Very few “complete”—nine-(or more)-inning games—are pitched by the starting pitchers. A manager will use a “pitch count” to determine how far his ace (the starting pitcher) can go. There are middle-inning (fifth–seventh inning) relief pitchers, and there are “closers,” who finish pitching the game. Relief pitching has become an art and a specialty. However, the statistics related to relief pitching have not kept pace. Assume the following situation. Several relief pitchers have come into a different number of games and have “inherited” a different number of base runners. However, all of these relief pitchers end the season with similar numbers of saves. Because the actual games each pitcher entered can be widely disparate, a fixed number of saves—say, 15—might not have the same value for each pitcher. It's possible that reliever no. 1 pitched in twice as many games as reliever no. 2. Clearly, in such a case, “15 saves” would not mean that they are of equal value. And what of the situations in which each of these pitchers allowed runs or scores and did not “save” the game (“blown saves”)? Most of the baseball statistics we know are readily computed and reflect simple performance parameters. The common and not-so-common items used to measure pitching performance in the major leagues today include “Adjusted Pitching Runs” (“APR” or “PR/A”). This is an advanced pitching statistic used to measure the number of runs that a pitcher prevents from being scored compared to the League's average pitcher in a neutral park in the same amount of innings. This is similar to the “ERA” (“Earned Run Average”) and acts as a quantitative counterpart. The abovementioned ERA is simply computed by the following formula: ERA = Rx9 I where R=the number of earned runs and I=total no. of innings pitched. The ERA is one of the oldest pitching statistics and is one of the most commonly used and understood statistics in the major leagues. Virtually every fan knows what it means, but many often forget the formula used to compute the pitcher's ERA. The Earned Run Average Plus (“ERA+” or “RA”) is computed by dividing the league ERA by the ERA of a pitcher. This statistic uses a league-normalized ERA in the calculation and is intended to measure how well the pitcher prevented runs from being scoring relative to pitchers in the rest of the league. It is similar to the Hitters' PRO statistic. Another commonly used statistic is the “Walks and Hits per Innings Pitched” (“WHIP”), which is computed as follows: WHIP = H + W I where H=number of hits, W=number of walks, and I=total number of innings pitched. There is a popular statistic that is probably used and frequently discussed in certain leagues. It was developed to measure the approximate number of walks and hits a pitcher allows in each inning he pitches, and then to compare the value received to other pitchers to formulate a pitcher's index. The winning percentage is another common statistic in baseball and is also quite easy to understand and easy to compute. The primary purpose of this statistic is to gauge the percentage of a pitcher's games that are won. In some instances, certain statistics become very sophisticated and more difficult to compute. Thus, for example, “Game Score” is computed as follows: GAMESCORE = 50 + 3 ⁢ I - 2 ⁢ ( H + R + E ) - W + S + 2 I ′ where I=the number of innings pitched; H=number of hits; R=number of runs; E=number of errors; W=number of walks; S=number of strikeouts; and I′=the number of each full inning completed beyond the fourth inning.This advanced pitching statistic is used to measure how dominant a pitcher's performance is in each game he pitches. This statistic rewards dominance (strikes and lack of hits) while penalizing for walks. As it clear from the above, the number of statistics that are followed by baseball enthusiasts is rather large. Some of these statistics are, of course, more important than others to either the fans or the ball clubs. While some of the aforementioned pitching statistics reflect a pitcher's general performance, only some of the statistics reflect the additional pressures and expectations of pitchers during critical phases of the game, when the pitchers are under particular stress. As noted, the “Game Score” is a function of full innings completed beyond the fourth inning and, therefore, reflects the performance of the pitcher toward the second half of the game. Most of the pitching statistics do not, however, reflect other parameters that are inherently stressful to all pitchers and that all good relief pitchers must overcome, including the number of outs, the number of inherited runners and the specific bases where each inherited runner is located when the relief pitcher comes on. As suggested, the number of outs, the number of inherited runners and the specific bases on which they are located, as well as the specific inning in which the pitcher comes in can, separately and in combination, be particularly stressful to a pitcher. The ability of a pitcher to overcome such stressful conditions and provide a win has never been quantified. This problem has been recently discussed in “Top Relievers: Earning Saves by Putting Out Others' Fires” in The New York Times (Jun. 27, 2004) Section 8, page 10. Although this problem has been well defined, to date there has been no practical solution to it. Accordingly, it is an object of the invention to provide a method of evaluating the performance of a relief pitcher in the final innings of a baseball game that provides an accurate measure of a pitcher's performance and value of the pitcher under stressful and/or critical conditions and allows such relief pitchers to be more accurately compared on an objective and/or quantitative basis with other relief pitchers. It is another object of the invention to provide a method, as in the previous object, that factors in parameters such as the number of the inning in which the relief pitcher is called in, the number of inherited runners, and the bases which they occupy, and the number of outs during the inning in which the relief pitcher is called in. It is still another object of the invention to provide a method as in the previous objects which computes a “Relief Quotient” (“RQ”) that is proportional to the total number of runs scored by inherited runners and inversely proportional to the total number of batters faced by the pitcher in the innings in which he pitches. It is yet another object of the invention to provide a method of the type under discussion which is simple to compute and yet provides a sophisticated and more refined method of evaluating and comparing the performances of relief pitchers by considering the number of runs scored by inherited runners and the number of batters faced during the final innings, but which can be refined by also factoring in the specific innings in which the runs by the inherited runners are scored, as well as the number of outs when the relief pitcher is introduced into the game. In order to achieve the above objects, as well as others that will become more apparent hereinafter, a method of evaluating the performance of a relief pitcher in the final innings of a baseball game in which the pitcher inherits at least one player on base comprises the steps of establishing the number of runs Ri scored by such inherited runners and establishing the number of batters B faced by the pitcher in such innings. The Relief Quotient (RQ), in accordance with the present invention, is evaluated by calculating it as follows: RQ = k ⁡ ( Ri + E B ) n where k=a first predetermined constant selected to scale the RQ to a desired range of magnitudes; Ri=the number of runs scored by inherited runners; B=the number of batters faced by the pitcher in these innings; E is a second constant, and may be equal to the pitcher's ERA; and n=a predetermined positive or negative number normally equal to +1 or −1. The attached FIGS. 1A, 1B and 1C and 2A, 2B and 2C are two spreadsheets illustrating examples of computations of Relief Quotients (RQs) in accordance with the present invention for two different relief pitchers. This RQ functions to more clearly define the value and performance of a relief pitcher. As things are now, a relief pitcher who comes into a game with his team ahead will, in circumstances previously described, receive a “save” (provided, of course, that the team stays ahead). But if several relief pitchers each have achieved the same number of saves, will each have the same value as a relief pitcher? The current use of baseball statistics does not provide an accurate tool by which to measure the value of a relief pitcher. Fortunately, using the RQ statistic we can now more clearly define relief pitcher superiority and compare relief pitchers more objectively and/or quantitatively than heretofore. For purposes of this invention, the RQ may either be computed on the basis of the number of outs that exist when the relief pitcher inherits players on base, or may be computed as a composite average for a given relief pitcher that reflects all instances in which players on base(s) are inherited with 0, 1 or 2 outs. Typically, the RQ is proportional to the number of runs Ri scored by players on base inherited by a relief pitcher, and inversely proportional to the total number of batters faced in the final innings of the game. Therefore, in its most fundamental or basic aspect, the RQ can be represented as follows: RQ = k ⁡ ( Ri + E B ) n where k is a predetermined constant selected to scale the RQ to a selected range of magnitudes, and may be equal to “1”. The exponent “n” may be +1 or −1, as to be more fully discussed below. In the initial embodiment discussed, the exponent is +1. However, as suggested, the RQ can be significantly refined to more fully reflect the value or performance of a relief pitcher in the final innings of the game. For purposes of discussing some such refinements, the following definitions will be used: (1) The Inning Factors (Fi)—Preferably, these factors exist for the seventh, eighth, and ninth innings only. Through the sixth inning there is less pressure for a relief pitcher, as the game has a substantial amount of time left. As the game enters the seventh inning, the pressure mounts for the relief pitcher to hold the opposite team back. The “Inning Factor” variable “Fi” is increased as the game progresses through the seventh, eighth, and ninth innings, as the pressure increases and as the amount of time to correct a miscue decreases for a team. In short, the RQ reflects a greater penalty for failure as the game progresses. (2) The Out Factors (F0, F1, F2)—the more outs there are when a relief pitcher enters the game, the more the reliever is penalized for a miscue. For example, if in the eighth inning with a runner on first base the pitcher allows the runner to score with one out he is penalized by a factor of 1.5; if he allows the runner to score with two outs the penalty “out factor” is 2.5. These factors are used because there is more pressure on the relief pitcher when he is pitching to a batter with, for example, two outs in the ninth inning than to a batter with no outs in that same inning. He is penalized more in these circumstances. (3) The Base Factors (R1, R2, R3)—It takes a greater miscue to allow a runner to score from first base than it does to allow one to score from third base. Thus, the pitcher is penalized to a greater extent if the player on first scores under the same conditions as in a situation in which the player on third scores. Turning now to specific examples of computations of RQs in accordance with a more refined formula in accordance with the invention, and first referring to FIGS. 1A, 1B and 1C, it should be noted that the tables or spreadsheets show cumulative data for a pitcher over a number of games and not just one game. The RQ may be calculated over a single game, a season or over a lifetime of games for a relief pitcher. In the initial column, the inning is indicated in which the relief pitcher enters. This can, of course, be in any inning, but, as noted above, the RQ only takes into account the seventh, eighth and ninth-plus innings. Because a game can include extra innings, and should the game go into such extra innings, the same variables, factors and constants as used for the ninth inning may also used for any succeeding inning(s). The second column provides an “Inning Factor.” It will be noted that the Inning Factor increases from Inning 7 to Inning 8 to Inning 9. The Inning Factor is designated as “Fi”. The third column in FIG. 1A lists a factor reflecting “0” or “no outs” during Innings 7, 8 and 9 , when a relief pitcher might be called in. The “Zero Out Factor” is represented by “F0”; this factor increases throughout the three final innings of the game. Thus, if a pitcher enters the seventh inning with no outs, he is not penalized. If he enters the eighth inning with no outs, and allows inherited runners to score, he is penalized. He is penalized even more, then, if he enters the ninth inning with no outs, and allows inherited runners to score. Similar factors F1 and F2 are used where there are 1 or 2 outs at the time the relief pitcher inherits a runner on base. The fifth, seventh and ninth columns list factors k1, k2 and k3. These factors represent parameters that are associated with inherited runners on first base, second base and third base, respectively. It will be noted that the factors k1, k2 and k3 decrease as the position of the inherited runner moves up from first to second to third base. Therefore, if an inherited runner on first base scores, the pitcher will be penalized more severely than if he enters the game with an inherited runner on third base, and that runner scores. The fourth, sixth and eighth columns set forth the inherited runners on respective bases that may be found when the relief pitcher enters the game. With the aforementioned data entered into the respective columns, a first component, “V0,” is computed as follows:V0=Fi×[(k1×R1)+(k2×R2)+(k3×R3)]+F0×[(k1×R1)+(k2×R2)+(k3×R3)]. The value V0 is computed for each inning during which inherited runners are on base when a relief pitcher enters the game. In the example given in FIG. 1A, in the 7th Inning, this relief pitcher has inherited one player on 1st base and one player on 3rd base. This yields a quantity V0=4.00. In the example shown in FIG. 1A, V0=50, on the basis of four inherited runners on first base, three inherited runners on second base and two inherited runners on third base, in the eighth inning, with no outs, and V0=52, on the basis of two inherited runners on first base, two inherited runners on second base and three inherited runners on third base in the ninth inning with no outs. In both cases, the V0 values are added to the V0 value associated with the seventh and ninth innings for a total value of V0=106. Similar computations are performed for FIGS. 1B and 1C, in which the factors k1 k2 and k3 are the same. The only difference from the first set of columns is that in the first column in this set (FIG. 1B), there is “one out” when the pitcher enters the game. For this reason, the first out factor F1 differs from the value F0 of column 3 in FIG. 1A. Thus, it will be noted that F1, for the same inning, will increase when there is one out, as opposed to no outs. Therefore, the pitcher is being more severely penalized if he enters the game with one out and an inherited runner scores than he would be if he had entered the game with no outs and that same runner scored. Again, using the same expression (2) above, values of V1 are computed for each inning as follows:V1=Fi×[(k1×R1)+(k2×R2)+(k3×R3)]+F1×[(k1×R1)+(k2×R2)+(k3×R3)].In this case, the total of the V1 values is 139. Finally, referring to FIG. 1C, similar computations are performed for the last seven columns in which the constants are the same with the exception that the first column for F2 is increased even further than the corresponding factors or values F0 and F1. For the same reasons mentioned previously, this is to penalize the pitcher more severely in the event that an inherited runner scores when there are two outs when the relief pitcher comes into the game. Again, using the same expression (2), the values V2 are computed for each inning as follows:V2=Fi×[(k1×R1)+(k2×R2)+(k3×R3)]+F2×[(k1×R1)+(k2×R2)+(k3×R3)].In the example shown in FIG. 1C, the total of V2 is equal to 172 on the basis of two runs in the seventh and ninth innings with players on first base. It will be noted that each of the quantities V0, V1 and V2 (equations 2, 3 and 4) reflects the number of runs scored, with each run R modified or weighted by the factor multipliers. The RQ can now been computed as follows, using formula (1) and using k=1 and B=270: RQ = 1 ⁢ ( V 0 + V 1 + V 2 ) B In the example illustrated, where the pitcher faced 270 batters,RQ=1(106+139+172)÷270RQ=1.54. The constant “1” is not critical for purposes of the present invention and is merely a scaling factor that can be selected to scale the general resulting computation to a number that is manageable, easy to remember or otherwise convenient. The RQ may also be scaled to a number that is generally consistent with other baseball averages, as both fans and clubs may be more familiar and more comfortable with them. As indicated in FIG. 1A, with a total of 90 batters faced by this relief pitcher, without any outs, the RQ may be computed asRQ=106.00÷90=1.18. Similarly, considering the relief pitcher's performance when he is brought in when there is one out, FIG. 1B shows one player on 1st base and one runner on 2nd base in the 7th Innings. This translates into V1=4.00. In the 8th Innings, this relief pitcher has had four inherited runners on 1st base, three runners on 2nd and two runners on 3rd for a V1=70.00. Likewise, in the 9th Innings, this pitcher has had two runners on 1st, two runners on 2nd and three runners on 3rd base for a V1=65.00. The three values of V1, summed, equal 139.00, which, when divided by B=90 total batters faced with one out, translates to an RQ of 1.54. Finally, in FIG. 1C, this same relief pitcher is shown to have been exposed to one inherited runner on 1st base and one on 3rd base in the 7th Innings, which again translates into a V2=4.00. In the 8th Innings, he has had four inherited runners on 1st, three on 2nd and two on 3rd, for V2=90.00. Two inherited runners on 1st, two on 2nd and three 3rd occurred in the 9th Inning, for a V2=78.00. The total of the V2 quantities is, therefore, 172.00. Considering a total of 90 batters faced in relief, with two outs, the RQ comes out to be 1.91. It should be noted, in this connection, that the number of inherited runners in FIGS. 1A, 1B and 1C are identical in this hypothetical example. Yet the total values for V0, V1 and V2 differ. This is because of the different weighing factors that penalize the pitcher under certain circumstances. Considering all of the games in which the pitcher was called in and had to deal with inherited runners, the overall performance of this relief pitcher can be computed as the sum of all the “V”-quantities, namely, V0, V1 and V2, divided by the total batters faced in relief, which, in the example, turns out to be 270. This provides a “lifetime” RQ for this relief pitcher of 1.54. In FIGS. 2A, 2B and 2C, similar computations are made in which different numbers of inherited runners are found on different bases with different numbers of outs. Here, using similar computations, the overall or “lifetime” RQ for the second pitcher is 1.74, after having faced a total of 215 batters. Similar computations can, of course, be made for all pitchers who are called during the later innings of a game to relieve an existing pitcher and who are faced with inherited runners on base. All these RQ numbers can then saved in a database and compared to each other. It is possible, then, to also compare relief pitchers insofar as their performance is concerned when called into a game with no outs but with inherited runners on base. In the two examples shown, in FIGS. 1A and 2A, the pitcher represented by the figures in 1A is the superior pitcher, as his RQ is 1.18, whereas the second pitcher has an RQ of 1.52. If both of these relief pitchers are on the same team, a manager of a baseball club, may decide in a critical game, to use the first relief pitcher under circumstances in which there are no outs. The same would be true if such relief pitchers were compared at a time when there is one out when a relief pitcher was needed, the first pitcher having an RQ, under those circumstances, of 1.54, while the second pitcher has an RQ of 1.64. Finally, if required to select a relief pitcher in any game in which there are two outs and inherited runners exist, the first relief pitcher has still demonstrated that he performs better under those conditions, have an RQ=1.91, whereas the second pitcher has an RQ of 2.49. Such superior performance is also reflected in the “lifetime” or overall better RQ for the first pitcher of 1.54 as compared to the “lifetime” RQ of the second pitcher, which is equal to 1.74. The distinctions between the RQ and ERA become immediately evident. Thus, for example, in a nine-inning game, with three outs per inning, there are a total of 27 outs. In the ideal game, therefore, there are 27 batters out in one game. T/he ERA, as noted above, is equal to the number of runs divided by the number of batters, itself divided by 27 (the number of outs). Therefore, in the ideal game, the number of runs is equal to zero, and the ERA is equal to zero. However, if the number of runs is equal to 1, the ERA is equal to 1. If the pitcher faces 54 batters, the ERA is equal to 0.5. Stated otherwise, the ERA is a reflection of the number of runners who have scored for every 27 outs. However, this is without regard to the number of inherited runners, the number of innings in which the runs were scored, the bases on which the inherited runners were on, etc. However, the RQ provides more information about the real performance of the relief pitcher. Thus, the greater the number of inherited runners that score, the higher the RQ. The RQ also increases if such runs are scored in later innings, or from lower bases. It will be evident, therefore, that the RQ provides a more accurate and more complete picture of the capabilities or performance of a relief pitcher in the circumstances described. By using the formula for the RQ, in its broader or more refined form, a numerical value can be placed on what the relief pitcher has saved. In other words, “a save is not a save is not a save.” All saves are not equal. The RQ in accordance with the present invention makes the necessary adjustment to reflect this and serves as a valuable tool and criterion for analysis when comparing relief pitchers in the final innings of a baseball game. Although this invention has been described in detail with particular reference to preferred embodiments thereof, it will be understood that variations and modifications may be effected within the spirit and scope of the invention as described herein and as defined in the appended claims. Thus, for example, formulas (2)–(4) can be modified to add, delete or give different weights to any of the factors that serve as multipliers for the runs R1, R2 and/or R3. The “out” factors F0, F1 and F2 may be discounted or made equal to zero. While this simplifies the computation, it eliminates the ability of those working with the data to vary the weight of the statistics to runs scored when there are different numbers of outs at the time that the relief pitcher is called in. It should also be clear that each of the factors (e.g., k1, k2, k3) can be adjusted to penalize a pitcher more or less as conditions vary. The factors can be incrementally increased or decreased, or can be inverted and adjusted as a divisor instead of a multiplier in the equations (e.g., (R1÷k1) instead of (R1×k1) as in equation (3)). Additional factors not currently reflected in the equations for the RQ might also be added—such as, for example, whether the game is a night game, poor weather conditions (e.g., rain)—all of which may make it easier or more difficult for a pitcher to perform well. As suggested previously, the exponent “n” can be any value that provides desired or reasonable values for RQ. Thus, in the above expression (1), “n” can be whole integers, fractions or any other numeric quantity. In accordance with the currently preferred realizations, normally n=1 or n=−1. Thus, in the example suggested by expression (4), RQ has been computed with n=1, so that the quantity (V0+V1+V2) remains in the numerator while the quantity B remains in the denominator, yielding RQ=1.91 when k=1. It is clear that when n=1, the RQ is proportional to the number of runs R scored and inversely proportional to the number of batters faced in the final innings of the game, so that as the ability of the relief increases, the RQ decreases. By scaling the constant k, RQ can be greater or less than one. If an inverse relationship is desired, “n” can be made equal to −1, which thereby places “B” in the numerator and “R” in the denominator. Again, k can be selected to provide any scale factor. However, when n=1, as the ability of the relief pitcher improves, the RQ decreases. Again, the absolute values can be adjusted by selecting a suitable value of k. In the examples given, with k remaining at 1, selecting n=−1 would make RQ=1×(90÷172)=0.523, instead of 1.91. It will be clear that reversing the sign of the exponent “n” simply reverses the trend for the pitchers—either the RQ increases or decreases as the player exhibits more and more (or less and less) skill. The above method may be presented in terms of program procedures executed on a computer or network of computers. These procedural descriptions and representations are the means used by those skilled in the art to most effectively convey the substance of their work to others skilled in the art. Here, generally, a “procedure” is conceived to be a self-consistent sequence of steps leading to a desired result. These steps are those requiring physical manipulations of physical quantities. Usually, though not necessarily, these quantities take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated. It proves convenient at times, principally for reasons of common usage, to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, or the like. It should be noted, however, that all of these and similar terms are to be associated with the appropriate physical quantities and are merely convenient labels applied to those quantities. Further, the manipulations performed are often referred to in terms, such as adding or comparing, which are commonly associated with mental operations performed by a human operator. No such capability of a human operator is necessary, or desirable in most cases, in any of the operations described herein which form part of the present invention; the operations are machine operations. Useful machines for performing the operations of the present invention include general purpose digital computers or similar devices. The present invention also relates to apparatus for performing these operations. This apparatus may be specially constructed for the required purpose or it may comprise a general purpose computer as selectively activated or reconfigured by a computer program stored in the computer. The procedures presented herein are not inherently related to a particular computer or other apparatus. Various general purpose machines may be used with programs written in accordance with the teachings herein, or it may prove convenient to construct more specialized apparatus to perform the required method steps. The required structure for a variety of these machines will appear from the description given. FIG. 3A illustrates a computer of a type suitable for carrying out the invention. Viewed externally in FIG. 3A, a computer system has a central processing unit 100 having disk drives 110A and 110B. Disk drive indications 110A and 110B are merely symbolic of a number of disk drives which might be accommodated by the computer system. Typically, these would include a floppy disk drive such as 110A, a hard disk drive (not shown externally) and a CD ROM or DVD drive indicated by slot 110B. The number and type of drives vary, typically, with different computer configurations. The computer has a display 120 upon which information is displayed. A keyboard 130 and mouse 140 are typically also available as input devices. The computer illustrated in FIG. 1A may be a SPARC workstation from Sun Microsystems, Inc. FIG. 3B illustrates a block diagram of the internal hardware of the computer of FIG. 3A. A bus 150 serves as the main information highway interconnecting the other components of the computer. CPU 155 is the central processing unit of the system, performing calculations and logic operations required to execute programs. Read only memory (160) and random access memory (165) constitute the main memory of the computer. Disk controller 170 interfaces one or more disk drives to the system bus 150. These disk drives may be floppy disk drives, such as 173, internal or external hard drives, such as 172, or CD ROM or DVD (Digital Video Disks) drives such as 171. A display interface 125 interfaces a display 120 and permits information from the bus to be viewed on display. Communications with external devices can occur over communications port 175. A data base of any conventional or suitable format may be provided and stored on any of the storage media 171, 172, 173, etc. Referring to FIG. 4, a block diagram is shown that illustrates the method of computing the runs quotients RQ in accordance with the invention, which is preferably performed by a computer of the type shown in FIGS. 3A and 3B. When performed by a computer, FIG. 4 illustrates the data that is entered into the computer as well as the computations performed by the computer on the basis of certain desired characteristics or properties for the RQ. Initially, a database needs to be created for each relief pitcher or group or universe of pitchers. To do this, the identity of each individual pitcher is inputted into the computer at 200. For that given pitcher, the number of runs “R1,” “R2” and “R3” is then inputted, representing the runs scored by the players that have been inherited by the relief pitcher, at 202. At 204, the total number of batters “B” are entered or inputted that have been faced by the relief pitcher. Once the aforementioned information has been inputted, the computer is instructed to compute a quantity Y=[(k1×R1)+(k2×R2)+(k3×R3)], at 206. Once the quantity Y has been computed, that quantity is multiplied by the Inning Factor Fi, (Fi×Y), at 208, and the base factors F0, F1 and F2 are used to obtain the products (F0×Y), (F1×Y) and (F2×Y), at 210. As aforementioned, the quantities can be scaled up or down depending on the general size or magnitude of the desired RQ quantity. The scale factor “k” is entered at 212, and a parameter E is entered at 214. As will become evident, the parameter E at 214 can be 1 or 0 or any desired quantity. At 216 an intermediate quantity W is then computed by multiplying the intermediate quantity Y in accordance with the following relationship:W=k[(FiY+F0Y)+(FiY+F1Y)+(FiY+F2Y)]. At 218 another intermediate parameter, Z, is computed to be equal to:Z=W+E. An inversion exponent “n” is then inputted at 220, depending what the preference is to have the RQ quantity increase with better relief pitcher performance, or whether the quantity needs to be decreased. It should be clear, therefore, that for positive values of “n”, lower values of the RQ parameter represent pitchers who have performed better, while the quantities increases as the performance decreases. The reverse is true for negative values of the inversion exponent “n”, since a negative exponent will invert the value of the RQ quotient, so that the larger the quantity, the better the performance. The RQ is computed at 222 in accordance with the following relationship: RQ = k ⁡ ( Ri + E B ) n . This quantity can then be stored in a suitable database, at 224. The computation of the RQ can be simplified if “E” is made equal to 0. However, the quantity “E” has been include in the generalized formula to accommodate the situation in which the inversion exponent “n” is negative, and the quantity “W” is equal to 0, as this would lead to very large, and even infinite, quantities for RQ. In this way, even if the quantity “W” is equal to 0, the ratio B/W can still be made to be a finite quantity. However, when the inversion exponent “n” is positive, the quantity W remains in the numerator, and the quantity E may be superfluous, and may be omitted. Under the conditions of the positive values of “n”, the basic equation for the RQ can be reduced to: RQ = ( W B ) n In FIG. 5 a practical application of the invention is illustrated. After the RQ is calculated for all relief pitchers of interest, this information is stored in a database, at 400, 402, 404. Once the “RQ”s—RQ1, RQ2 . . . RQm—have been stored, this information can readily be used to compare the RQ for any given pitcher to those of the others, at 406. This information can then be tabulated or displayed in any desired format, such as ascending or descending order, at 408. Once structured or tabulated, the information can be displayed, at 410, printed, at 412, or transmitted to a remote terminal, at 414. It should be evident that this information presented as suggested would be extremely useful to owners of sports teams, managers, fans, sports publications and the like, both to appreciate the relative performances of relief pitchers and for assessing future decisions on the basis of past performance.
	abstract	A controlled electron beam and heat will decrease the birefringence of a halogenated optical material under tensile stress. The electron beam and heat irradiation will occur in a chamber under near vacuum conditions. After electron beam irradiation and heating, the crystalline structure of the halogenated optical material layer has been randomized and made amorphous. The electron beam irradiation and heating will lower the high index of refraction of the halogenated optical material under stress and raise the low index of refraction of the halogenated optical material under stress. The differences in index of refraction between the high index of refraction area of and the low index of refraction area decrease which decreases the birefringence of the halogenated optical material under stress.
	claims	1. An apparatus comprising:a beam generator to generate a charged particle beam towards a specimen to cause electrons and X-rays to emanate from the specimen;an electron detector disposed adjacent to the specimen to detect electrons and their energies emanating from at least a first layer of the specimen;an X-ray detector disposed adjacent to the specimen to detect X-rays having characteristic energies for elements in at a second layer of the specimen; andlogic to receive a first signal from the electron detector and a second signal from the X-ray detector, wherein the logic:performs a first set of data analysis tasks based on the second signal; andaugments a result of the first set of data analysis tasks based on the first signal. 2. The apparatus of claim 1, wherein the logic determines film stack characteristics of the specimen. 3. The apparatus of claim 1, wherein the first layer comprises one or more bottom layers of the specimen. 4. The apparatus of claim 1, wherein the second layer comprises a layer that lies beneath the first layer of the specimen. 5. The apparatus of claim 1, wherein the first signal corresponds to an element and the second signal corresponds to the element. 6. The apparatus of claim 5, wherein the logic selects one of the first signal or the second signal to perform analysis regarding the element. 7. The apparatus of claim 1, wherein the logic comprises a processor coupled to the beam generator, the X-ray detector, and the electron detector. 8. The apparatus of claim 1, further comprising a plurality of X-ray detectors. 9. The apparatus of claim 1, wherein the characteristic energies are measured simultaneously by the X-ray detector and the electron detector. 10. The apparatus of claim 1, wherein the electron detector is to detect Auger electrons emanating from the specimen. 11. The apparatus of claim 1, wherein the specimen comprises a semiconductor wafer. 12. The apparatus of claim 1, wherein the electron detector comprises a cylindrical mirror analyzer. 13. The apparatus of claim 1, wherein the beam generator comprises a scanning electron microscope. 14. The apparatus of claim 1, wherein the beam is configured to penetrate at least two layers of a film stack disposed on the specimen. 15. The apparatus of claim 1, wherein a spot size of the beam directed at the specimen is less than about 100 microns in diameter. 16. A method comprising:directing a charged particle beam towards a specimen to cause X-rays and electrons to emanate from the specimen;detecting electrons and their energies for a first layer of the specimen;generating a first signal in response to detecting of the electrons;detecting X-rays from elements contained in a second layer of the specimen;generating a second signal in response to detecting the X-rays;performing a first set of data analysis tasks based on the second signal; andaugmenting a result of the first set of data analysis tasks based on the first signal. 17. The method of claim 16, further comprising measuring at least one characteristic of a film stack on the specimen. 18. The method of claim 16, wherein detecting the electrons comprises detecting Auger electrons. 19. The method of claim 16, wherein detecting the X-rays comprises detecting X-rays of a specific energy. 20. The method of claim 16, wherein the X-rays are detected from at least one element in a layer of material underneath the first layer.
	claims	1. A garment for use during procedures that expose a portion of a user to high energy radiation from a radiation source, comprising:a disposable short-use flexible garment member;said disposable short-use flexible garment member having an opening for encircling the user's waist and having two openings for receiving the user's legs;a means for removably securing said disposable short-use flexible garment member on said user prior to receiving said high energy radiation;a first pocket defining member located on an outer surface of said disposable short-use flexible garment member for removably receiving a first flexible shielding member there withinsaid disposable short-use flexible garment member extending beyond a side edge of said first pocket defining member;at least one attachment portion located on the outer surface of said disposable short-use flexible garment member for attaching a second flexible shielding member, wherein the attachment portion is positioned relative to the first pocket defining member such that when the second flexible shielding member is attached via the attachment portion it partially overlaps the first flexible shielding member within the first pocket defining member. 2. A garment, according to claim 1, wherein:the at least one attachment portion for attaching said second flexible shielding member is a second pocket defining member. 3. A garment, according to claim 1, wherein:said means for securing said disposable short-use flexible garment member on said user further comprises, at least one means for releasably securing said disposable short-use flexible garment member on said user selected from the group comprising:an adhesive member, a mechanical securing member, a magnetic member, a string-tie member, a strap member, a mechanical snap member, a hook-and-loop based mechanical fastener member; and an elastic member. 4. A garment, according to claim 1, wherein:the at least one attachment portion includes at least one of a removable pocket defining member, a pocket defining member immovably fixed to said disposable short-use flexible garment member, a hook-and-loop based mechanical fastener system, a mechanical snap member, a string-tie member, a strap member, and an adhesive member. 5. A garment, according to claim 1, wherein:said disposable short-use flexible garment member is constructed from at least one of a woven layer material and a non-woven layer material. 6. A garment, according to claim 5, wherein:said disposable short-use flexible garment member is constructed from said non-woven layer material; andsaid non-woven layer material is one of an inelastic material and an elastic material. 7. A garment, according to claim 1, further comprising:a plurality of additional pocket defining members located on an outer surface of said disposable short-use flexible garment member defining a respective plurality of pocket locations for removably receiving a respective plurality of flexible shielding members there-within during a use thereof. 8. A garment, according to claim 1, wherein:said first pocket defining member extends from the top of the garment down to between the garment's leg openings on the front side of the user's body. 9. A garment according to claim 8, further comprising an additional pocket defining member from the top of the garment down to between the garment's leg openings on the rear side of the user's body. 10. A garment according to claim 1, wherein said means for securing said disposable short-use flexible garment member on said user further comprises an elastic waist member for securing the garment around the user's waist. 11. A garment for use during procedures that expose a portion of a user to high energy radiation from a radiation source, comprising:a disposable short-use flexible garment member;said disposable short-use flexible garment member having a length greater than a width, wherein the width is between about 2 inches to about 5 inches;a means for removably securing the garment around a user's neck wherein the length of the garment member encircles the user's neck;a means for removably securing said disposable short-use flexible garment member around the user's neck prior to receiving said high energy radiationa pocket defining member on said disposable short-use flexible garment member for removably receiving a flexible shielding member therewithin;a means for removably securing a second flexible shielding member to the outer surface of said short-use flexible garment member, wherein said second flexible shielding member is positionable such that it overlaps said first shielding member. 12. A garment for use during procedures that expose a portion of a user to high energy radiation from a radiation source, comprising:a generally rectangular disposable short-use flexible garment member having a front panel and a back panel;said disposable short-use flexible garment member further comprising a means for removably securing said disposable short-use flexible garment member on said user prior to receiving said high energy radiation wherein the front panel lays against the user's front and the back panel lays against the user's back;said means for removably securing the garment on the user includes at least one of an adhesive member, a mechanical securing member, a magnetic member, a string-tie member, a strap member, a mechanical snap member, a hook-and-loop based mechanical fastener member; and an elastic member;a pocket defining member located on an outer surface of the front panel of said disposable short-use flexible garment member for removably receiving a first flexible shielding member there within; anda means for removably securing a second flexible shielding member to an external region of the front panel of said disposable short-use flexible garment member, wherein said second flexible shielding member is positionable such that it overlaps a portion of said first flexible shielding member. 13. A garment, according to claim 12, wherein said means for removably securing a second flexible shielding member includes at least one of a removable pocket defining member, a pocket defining member immovably fixed to said disposable short-use flexible garment member, a hook-and-loop based mechanical fastener system, a mechanical snap member, a string-tie member, a strap member, and an adhesive member. 14. A garment for use during procedures that expose a portion of a user to high energy radiation from a radiation source, comprising:a generally rectangular disposable short-use flexible garment member having a front panel and a back panel;said disposable short-use flexible garment member further comprising a means for removably securing said disposable short-use flexible garment member on said user prior to receiving said high energy radiation, wherein the front panel lays against the user's front and the back panel lays against the user's back;said means for removably securing the garment on the user includes at least one of an adhesive member, a mechanical securing member, a magnetic member, a string-tie member, a strap member, a mechanical snap member, a hook-and-loop based mechanical fastener member; and an elastic member;a first pocket defining member located on an outer surface of the front panel of said disposable short-use flexible garment member for removably receiving a first flexible shielding member there within; anda second pocket defining member for removably receiving a second flexible shielding member, wherein the second pocket defining member is positioned relative to the first pocket defining member such that when the second flexible shielding member is placed in the second pocket defining member it partially overlaps the first flexible shielding member when placed in the first pocket defining member.
	summary
058621962	abstract	A spacer including a plurality of cells to retain and mutually fix parallel, elongated elements, extending through the cells, in a bundle in a fuel assembly for a nuclear reactor where a coolant is adapted to flow from below and upwards. Between the cells, secondary channels are formed. At least one of the spacers includes at least two deflection members being substantially arranged so as to be surrounded by the cells. The deflection members are axially spaced-apart in the direction of flow of the coolant and relative to each other at a pitch angle for stepwise axial and radial deflection and guiding of at least part of the coolant flow towards fuel rods included in the bundle. The fuel rods are arranged close to the secondary channels.
041918886	claims	1. In an ion extraction system utilizing small hole accel grid optics and comprising within a discharge chamber a neutral highly ionized plasma source at a first voltage V.sub.1, V.sub.1 being positive, a plurality of electrodes downstream of said plasma source each having apertures in axial alignment and including in the following order a screen grid at said first voltage V.sub.1 and an accel grid at a second voltage V.sub.2, V.sub.2 being negative, said accel grid having a relatively small aperture in the range of less than 50% to approximately 10% the size of the aperture of said screen grid, the electric field set up by said screen grid and said accel grid serving to extract an ion beam from the plasma source and focus the ion beam through the accel grid aperture, the improvement wherein said accel grid is provided with a relatively large aperture and a metallic foil on at least the downstream face thereof covering said large aperture, said relatively small aperture being etched in the metallic foil by the ion beam. 2. The improved accel grid structure recited in claim 1 further comprising a metallic foil on the upstream face of the accel grid and covering said large aperture, a relatively small aperture also being etched in the metallic foil on the upstream face by the ion beam. 3. The improved accel grid structure recited in claims 1 or 2 wherein the metallic foil is a thin foil of tantalum. 4. The improved accel grid structure recited in claim 1 wherein the accel grid is copper and the metallic foil is nickel.
	summary
054897351	abstract	A decontamination composition comprises 40 to 60 percent of a compound selected from the group consisting of oxalic acid, alkali metal and ammonium salts of oxalic acid and mixtures thereof; 5 to 20 percent of a compound selected from the group consisting of citric acid, alkali metal and ammonium salts of citric acid and mixtures thereof; 20 to 40 percent of a compound selected from the group consisting of polyaminocarboxylic acid, alkali metal and ammonium salts of polyaminocarboxylic acid and the combination of a polyaminocarboxylic acid and a neutralizing compound, and mixtures thereof; 0 to 2 percent of a nonionic surfactant; about 0 to 2 percent of a dispersant; and about 0 to 2 percent of a corrosion inhibitor. The present invention also relates to a method of decontaminating a surface whereby contaminants in the form of NORMs are removed therefrom.
051006103	claims	1. A system for inspecting a tube plug defining a chamber therein and having an open end in communication with the chamber, the chamber having disposed therein an expander element having a bore therethrough, comprising: (a) probe means having a sensor probe connected thereto for inspecting the tube plug, said probe means capable of being connected to the tube plug for extending the sensor probe a predetermined distance into the chamber through the open end of the tube plug; (b) means connected to the probe means for rotating and translating the sensor probe within the chamber to provide an inspection scan interiorly of the tube plug, said rotating and translating means including: (c) drive means engaging said rotating and translating means for driving said rotating and translating means. (a) a probe carrier housing capable of being extended through the open end of the tube plug, into the chamber and through the bore of the expander element, said probe carrier housing having the sensor probe disposed therein for housing the sensor probe and for carrying the sensor probe through the bore of the expander element; and (b) limit means connected to said probe carrier housing for delimiting the extent said probe carrier housing is extended through the bore of the expander element. a cable extending longitudinally through said hose for operating said actuator means, said cable having one end thereof attached to said actuator means. (a) an adaptor assembly connected to said hose for connecting said hose to said drive means, said adaptor assembly attached to the other end of the cable for moving the cable; and (b) means connected to said hose and to the cable for rotating said hose so that said probe carrier housing is rotated and for moving said cable for operating said actuator. (a) a probe assembly abuttable against the open end of the tube plug for extending a sensor probe therefrom through the open end of the tube plug, into the chamber, and through the bore of the expander element, said probe assembly having the sensor probe connected thereto for inspecting the upper interior portion of the tube plug; (b) a hose connected to said probe assembly for transversely rotating and longitudinally translating the sensor probe along the longitudinal axis of the tube plug, said hose capable of translating the sensor probe through the bore defined by the expander element for inspecting the upper interior portion of the tube plug, said hose including: (c) a probe driver assembly connected to said hose for driving said hose. (a) an elongated probe carrier housing connected to said hose and sized to extend through the bore of the expander element, said probe carrier housing having external threads and having the sensor probe disposed therein for housing the sensor probe and for carrying the sensor probe through the bore of the expander element to inspect the upper interior portion of the tube plug, said probe carrier housing having a slot adjacent the sensor probe for passage of the sensor probe therethrough; (b) a spring connected to the sensor probe for biasing the sensor probe radially outwardly through the slot of said probe carrier housing to inspect the tube plug and for biasing the sensor probe radially inwardly through the slot of said probe carrier housing to protect the sensor probe from damage; and (c) an elongated extension member defining a passage therethrough surrounding said probe carrier housing, the passage having internal threads for threadably engaging the external threads of said probe carrier housing. (a) a first collar slidably surrounding said extension member, said first collar having a shoulder thereon for abutting the open end of the tube plug; (b) a second collar spaced apart from said first collar and defining a first opening and a second opening through said second collar, said second collar connected to and surrounding said extension member; (c) a spring member surrounding said extension member and interposed between said first collar and said second collar for biasing the shoulder into abutment against the open end of the tube plug; (d) an elongated first guide having a distal end portion thereof anchored in said first collar and having a proximal end portion thereof slidably received through the first opening defined by said second collar; (e) an elongated second guide having a distal end portion thereof anchored in said first collar and having a proximal end portion thereof slidably received through the second opening defined by said second collar, said second collar having an elongated indicator pin slidably extending therethrough, the indicator pin having a distal end and a proximal end; and (f) a plate surrounding and connected to said probe carrier housing, said plate spaced apart by a predetermined distance from the proximal end of the indicator pin. (a) a frame; (b) a guide rail attached to said frame, said guide rail having a groove therein; (c) a platform having a flange integrally attached thereto for slidably engaging the groove in said guide rail; (d) a shelf attached to said platform; and (e) an adaptor assembly connected to said shelf and to said hose for connecting said hose to said shelf. (a) a slide tube; (b) a pulley rotatably engaging said slide tube for rotating said slide tube; (c) a motor engaging said pulley for rotating said pulley; (d) whereby as said pulley is rotated by said motor, said slide tube and said hose rotate for rotating said probe carrier housing; (e) whereby as said probe carrier housing rotates, said probe carrier housing threadably engages said extension member for rotatably threadably translating said probe carrier housing through the passage defined by said extension member so that said probe carrier housing rotatably translates through the open end of the tube plug, into the chamber and through the bore of the expander element; (f) whereby as said probe carrier housing rotatably translates through the bore of the expander member, the sensor probe rotatably translates for providing a helical inspection scan of the upper interior portion of the tube plug; and (g) whereby as said probe carrier housing translates, said plate translates and abuts the proximal end of the indicator pin for pushing the indicator pin through said second guide for delimiting the extent of insertion of said probe carrier housing into the tube plug. (a) an elongated generally cylindrical probe carrier housing sized to extend through the bore of the expander element, said probe carrier housing having external threads therearound and having a sensor probe disposed therein for housing the sensor probe and for carrying the sensor probe through the bore of the expander element to inspect the upper interior portion of the tube plug, said probe carrier housing having a longitudinal slot therein adjacent the sensor probe for passage of the sensor probe therethrough, said probe carrier housing having a rounded cam attached thereto adjacent the slot; (b) an elongated generally cylindrical extension member defining a passage therethrough surrounding said probe carrier housing, the passage having internal threads for threadably engaging the external threads of said probe carrier housing, said extension member capable of abutting the bottom surface of the expander element; (c) a generally cylindrical first collar slidably surrounding said extension member, said first collar having a depending circular shoulder thereon for abutting the open end of the tube plug; (d) a generally cylindrical second collar spaced apart from said first collar, said second collar connected to and surrounding said extension member and defining a first opening and a second opening through said second collar; (e) a helical spring member surrounding said extension member and interposed between said first collar and said second collar for biasing said first collar into abutment against the open end of the tube plug; (f) an elongated generally cylindrical first guide having a distal end portion thereof anchored in said first collar and having a proximal end portion thereof slidably received through the first opening defined by said second collar; (g) an elongated generally cylindrical second guide having a distal end portion thereof anchored in said first collar and having a proximal end portion thereof slidably received through the second opening defined by said second collar, said second collar having an elongated indicator pin slidably extending therethrough, the indicator pin having a distal end and a proximal end; (h) a plate assembly surrounding and connected to said probe carrier housing, said plate spaced apart by a predetermined distance from the proximal end of the indicator pin; (i) a generally cylindrical rotator connected to said probe carrier housing for rotating said probe carrier housing, said rotator having a step bore therethrough; (j) a generally cylindrical actuator disposed in the bore of said rotator; and (k) an elongated leaf spring extending longitudinally through said probe carrier housing and having a cam surface thereon adjacent the cam and capable of slidably engaging the cam surface for biasing the sensor probe radially outwardly through the slot of said probe carrier housing to inspect the tube plug and for biasing the sensor probe radially inwardly through the slot of said probe carrier housing to protect the sensor probe from damage, said leaf spring having a proximal end thereof attached to the actuator and a bent distal end thereof having the sensor probe connected thereto, the distal end of the leaf spring disposed adjacent the slot of said probe carrier housing for biasing the sensor probe through the slot. (a) a frame having a vertical leg and a horizontal leg attached to said vertical leg, so that said frame defines an L-shape transverse cross section; (b) a first guide rail attached to the vertical leg of said frame, said first guide rail having a vertical groove in a marginal edge thereof; (c) a second guide rail attached to the vertical leg of said frame and spaced apart from said first guide rail, said second guide rail having a vertical groove in a marginal edge thereof; (d) a first platform slidably engaging said first guide rail, said first platform having a flange integrally attached thereto for slidably engaging the groove in said first guide rail; (e) a second platform slidably engaging said second guide rail, said second platform having a flange integrally attached thereto for slidably engaging the groove in said second guide rail; (f) a top shelf attached to said first platform and to said second platform, said top shelf having a step bore therethrough; (g) a bottom shelf attached to said first platform, to said second platform, and to said top shelf said bottom shelf spaced apart from said top shelf; (h) a first pulley and a second pulley interposed between and rotatably connected to said top shelf and said bottom shelf, said first pulley having a motor connected thereto for rotating said first pulley, said second pulley having a bore therethrough, said first pulley and said second pulley interconnected by a continuous pulley belt, so that said first pulley and said second pulley rotate as said first pulley is rotated by the motor; and (i) a pneumatic cylinder connected to said second shelf for raising and lowering said first shelf and said second shelf. (a) a generally cylindrical barrel having a bore longitudinally therethrough and having a flange surrounding a proximal end thereof so that the flange is matingly receivable in the step bore formed through said top shelf; (b) a generally cylindrical tube nozzle having a bore longitudinally therethrough and having and end of the hose connected to the distal end of said tube nozzle, said tube nozzle extending outwardly from the bore of said barrel, said tube nozzle having a flange surrounding the proximal end thereof; (c) a generally cylindrical slide tube extending through the bore of said second pulley, said slide tube connected to said tube nozzle and to said second pulley, for rotating said slide tube as said second pulley rotates and for rotating said tube nozzle as said slide tube rotates so that said hose rotates; (d) a generally cylindrical slide disposed in the bore of said slide tube, said slide having a bore therein and a circumferential slot extending around the proximal end thereof, said slide having the proximal end of the cable attached thereto for operating the cable; (e) a brace having a slide holder having tines capable of engaging the slot in said slide; and (f) a pneumatic cylinder assembly connected to said brace for raising and lowering said brace for operating the cable so that said actuator is actuated; (g) whereby as said actuator is operated, said leaf spring is operated so that the cam surface slidably engages the cam for outwardly extending the sensor probe to inspect the upper interior portion of the tube plug and inwardly retracting the sensor probe to protect the sensor probe from damage. 2. The system according to claim 1, wherein said probe means comprises: 3. The system according to claim 2, wherein said probe means further comprises biasing means connected to the sensor probe for biasing the sensor probe radially outwardly from said probe carrier housing to inspect the tube plug and for biasing the sensor probe radially inwardly into said probe carrier housing to protect the sensor probe from damage. 4. The system according to claim 3, wherein said probe means further comprises actuator means connected to said biasing means for actuating said biasing means. 5. The system according to claim 4, wherein said rotating and translating means comprises 6. The system according to claim 5, wherein said drive means comprises: 7. A system for inspecting a tube plug capable of being received within a tube for sealing the tube, the tube plug defining a longitudinal axis therethrough and a chamber therein having an expander element disposed in the chamber for expanding the tube plug into sealing engagement with the tube, the expander element having a top surface and a bottom surface thereon and a bore therethrough, the tube plug having a closed end and an open end in communication with the chamber, the tube plug having an upper interior portion between the top end of the tube plug and the top surface of the expander element, comprising: 8. The system according to claim 7, wherein said probe assembly comprises: 9. The system according to claim 8, further comprising limit means connected to said probe assembly for delimiting the extent said probe carrier housing extends through the bore of the expander element. 10. The system according to claim 9, wherein said limit means comprises: 11. The system according to claim 10, wherein said hose further comprises a cable extending longitudinally through said hose for operating said spring, said cable having one end thereof connected to said spring. 12. The system according to claim 11, wherein said probe driver assembly comprises: 13. The system according to claim 12, wherein said adaptor assembly comprises: 14. The system according to claim 13, wherein the cable belonging to said hose has one end thereof connected to said adaptor assembly and the other end thereof connected to said spring for actuating said spring. 15. In a nuclear steam generator, a system for inspecting a tubularly-shaped tube plug capable of being received within a steam generator tube for sealing the tube, the tube plug defining a longitudinal axis therethrough and a inwardly tapered chamber therein, the tube plug having an exteriorly tapered and generally cylindrical expander element disposed in the chamber for expanding the tube plug into sealing engagement with the tube, the expander element having a top surface and a bottom surface thereon and a cylindrical bore therethrough, the tube plug having a closed distal end and an open proximal end in communication with the chamber, the tube plug having an upper interior portion defined by the top end of the tube plug and the top surface of the expander element, comprising a probe assembly including: 16. The system according to claim 15, further comprising a flexible hose connected to said rotator for rotating said rotator, said hose having a plurality of adjacent segments, said hose including a generally cylindrical connector interposed between adjacent segments of said hose for maintaining tension in said hose so that said hose is tangle-free, said hose having a flexible cable extending therethrough, the cable having a distal end attached to said actuator for operating said actuator; 17. The system according to claim 16, further comprising a probe driver for driving said hose, said probe driver including: 18. The system according to claim 17, wherein said probe driver comprises an adaptor assembly connected to said hose for connecting said hose to said probe driver. 19. The system according to claim 18, wherein said adaptor assembly comprises:
	abstract	There is provided a particle-beam energy changing apparatus that is capable of changing energy of a particle beam quickly and silently, in which a first energy changing unit and a second energy changing unit for changing energy of a particle beam passing therethrough by varying thicknesses of their attenuators attenuating the particle beam energy are arranged so that the particle beam passes through the first energy changing unit and the second energy changing unit; and the maximum attenuation amount by the first energy changing unit is set smaller than the maximum attenuation amount by the second energy changing unit.

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