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06069937&	summary	FIELD OF THE INVENTION The present invention relates to illumination apparatus and exposure apparatus, and in particular to illumination apparatus for use with soft X-ray projection exposure apparatus BACKGROUND OF THE INVENTION An exposure apparatus for semiconductor manufacturing is one that projects and transfers a circuit pattern formed on the surface of an object, such as a photomask (hereinafter, simply "mask"), onto a substrate, such as a wafer, through an image-forming apparatus, such as a projection lens. The substrate is coated with a light-sensitive material, such as photoresist. Upon exposure of the mask, a photoresist pattern is obtained on the substrate. To obtain a photoresist pattern over a desired area (i.e., exposure field), the mask must be illuminated by light having a uniform intensity and a uniform divergence angle. Accordingly, the illumination apparatus of such exposure apparatus have employed Kohler illumination to satisfy these conditions. If the exposure light is X-rays, then the image-forming apparatus comprises a reflector. An off-axis circular arc-shaped (i.e., arcuate) exposure field is used, so that only an arcuate area on the mask is projected and transferred onto the wafer in a static exposure. Accordingly, the transfer of the circuit pattern on the entire mask onto the wafer is performed by simultaneously scanning the mask and wafer in fixed directions. In a scanning-type exposure, it is desirable that the illumination optical system uniformly illuminate the entire arcuate area on the mask at a fixed numerical aperture. An illumination optical system that can accomplish this is disclosed in Japanese Patent Application Kokai No. Hei 7-235471, applied for by the present applicant. The optical system disclosed in the above-mentioned Japanese Patent Application is shown herein in FIG. 6 and FIG. 7. X-rays 120, comprising beams 121 and 122, are emitted from light source (or light source image) 110 and are reflected by a special reflector 130, thereby forming convergent beams 124 and 125, respectively, which irradiate an arcuate area 140 on the mask (not shown). Arcuate area 140 is centered about a point 144 (see FIG. 6), and an X-Y-Z coordinate system is shown for reference. As an example of a method of forming a light source for an illumination optical apparatus, an illumination apparatus of high illumination intensity is disclosed in Japanese Patent Application Kokai No. Hei 8-148414, applied for by the present applicant. With reference now to FIG. 8, illumination optical system 100 comprises an excitation energy light generation unit 101, a target member 103, and an illumination optical system 104 as the principle components. Excitation energy light rays 102 emitted from unit 101 irradiate a plurality of locations 110 on target member 103. X-rays 120 are respectively generated from locations 110, thereby forming a plurality of X-ray sources 110 (i.e., locations 110 become X-ray sources 110). With reference now to FIGS. 9, 10a and 10b, parallel x-ray beams 121 and 122 are emitted from sources 110 in the sagittal direction (i.e., in the plane of the paper). When the emission angle .theta. is 0 degrees, beam 121 has a diameter p(.theta.)=q. When the emission angle is .theta., beam 122 has a diameter p(.theta.)=q.multidot.cos .theta.. Light beam diameter p(.theta.) (in the plane of the paper) decreases as emission angle .theta. increases. Accordingly, with reference now to FIGS. 10a and 10b, the cross section of beam 121 when the emission angle is 0 degrees is nearly circular (see FIG. 10a). This is in contrast to the cross section of beam 122, which cross section is elliptical when the emission angle is .theta. (see FIG. 10b). Beam 122 cross section (FIG. 10b) has a major axis p(0) in the meridional direction (i.e., perpendicular to the plane of the paper in FIG. 9) and a minor axis p(.theta.) in the sagittal direction. With reference now to FIG. 11, when parallel beam 121, having an emission angle of 0 degrees (see FIG. 9), is subject to the converging action of reflector 130 (see FIG. 7), convergent beam 124 is formed. Beam 124 is conical and constantly extends an equal angle with respect to convergence point P1 in an arcuate illumination area (field) BF formed on the object (not shown) to be irradiated. In contrast, when parallel light beam 122, having an emission angle of .theta. (see FIG. 9) is subject to the converging action of reflector 130 (see FIG. 7), convergent light beam 125 is formed. Beam 125 converges in an elliptical spindle-shape at convergence point P2 in arcuate illumination area (field) BF on the object (not shown) to be irradiated. Consequently, in the radial direction R at convergence point P2, the angle that convergent beam 125 extends with respect to convergence point P2 is equal to that of parallel beam 121 mentioned above. However, in the tangential direction T at convergence point P2, the angle that convergent light beam 125 extends with respect to convergence point P2 is smaller than that in the radial direction R at convergence point P2 (a multiple of cos .theta.). In addition, this effect is pronounced for parallel light beams with a large emission angle .theta. with respect to the sagittal direction. Thus, if an object is illuminated by an illumination apparatus which forms convergent light beams of a different cross-sectional shape, and an image of the object is formed by an image-forming apparatus, then the resolution of the image thus formed is generally not uniform over the image plane (exposure field). This is because a portion of the object is illuminated under conditions that do not satisfy the numerical aperture required by the image-forming apparatus. Japanese Patent Application Kokai No. Hei 6-267894 discloses a method to solve the above-described problem by using a new image-forming optical system. However, since this optical system comprises a plurality of lenses, it is not useful in the X-ray region wherein lenses cannot be used. In addition, even the optical system disclosed therein comprised reflectors, the amount of X-rays obtained after reflection would be extremely small, since a plurality of reflectors would be necessary. SUMMARY OF THE INVENTION The present invention relates to illumination apparatus and exposure apparatus, and in particular to illumination apparatus for use with soft X-ray projection exposure apparatus. An objective of the present invention is to provide a high-performance illumination apparatus, wherein the illumination efficiency is markedly higher than in conventional apparatus, and the numerical aperture of the X-rays at the illumination area formed in a circular arc (i.e., an arcuate area) is nearly uniform, independent of the illumination position. A first aspect of the invention is an illumination apparatus for illuminating an object. The apparatus comprises an excitation energy light generation unit for generating excitation energy light rays, and a target member having a curved surface and plurality of X-ray sources provided thereon. The plurality of X-ray sources emit X-rays when irradiated by the light rays. The target member is positioned relative to the light generation unit so that at least some of the light rays intercept the curved surface. The illumination apparatus further includes an illumination optical system that images the X-rays from the plurality of X-ray sources onto the object to be illuminated. Since the plurality of X-ray sources is arranged on a curved surface, the numerical aperture at the illumination area formed in a circular arc is nearly uniform and independent of the illumination position. Consequently, the required numerical aperture of an image-forming optical system, used in combination with the illumination apparatus of the present invention, is met over the entire object. As a result, the imaging resolution is uniform over the entire image plane of the imaging-forming optical system. A second aspect of the invention is the illumination apparatus as described above, wherein the curved surface of the target member is a cylindrical surface. The cylindrical surface can be easily manufactured and, in addition, the numerical aperture of the X-rays at the illumination area formed in a circular arc can easily be made nearly uniform, independent of the illumination position. A third aspect of the invention is an illumination apparatus as described above, wherein the target member is tape-shaped and is provided along the curved surface. In so doing, the numerical aperture at the illumination area formed in a circular arc is nearly uniform, independent of the illumination position. In addition, the tape-shaped target member can be moved in accordance with the level of wear of the target member, and a new part can receive the excitation energy light rays. Thus, the illumination apparatus can be used over a long period of time. A fourth aspect of the invention is an illumination apparatus as described above, wherein a particulate target member is used in the first means or second means, and is constituted so that a plurality of target members is formed on a curved surface. In so doing, the numerical aperture at the illumination area formed in a circular arc is nearly uniform, independent of the illumination position. In addition, the target member can be supplied continuously and, moreover, the amount of dispersed matter from the target member can be reduced. A fifth aspect of the invention is an illumination apparatus as described above, wherein the target member is a liquid or a gas. As used herein, the phrase "liquid or a gas" means that it is a liquid or a gas at room temperature and room pressure. When used as a target member, it is possible that they may also be a solid or a liquid, respectively. A sixth aspect of the invention is a method of illuminating an object. The method comprises the steps of first, providing a target member having a curved surface, then irradiating the curved surface at a plurality of locations with excitation energy light rays. The next step is emitting X-rays from the plurality of locations. Then, the final step is imaging X-rays from the X-ray sources onto the object. In a preferred embodiment, the latter step involves providing an illumination optical system adjacent the target member, and then imaging the X-rays through the illumination optical system.
045368821	claims	1. A method of making an X-ray mask for X-ray lithography comprising the steps of: providing a substrate for supporting the mask membrane of the X-ray mask during fabrication thereof; depositing a thin layer of material which is opaque to X-ray or charged particle radiation on said substrate, said thin layer having a thickness less than that of said substrate; patterning said thin layer to form a mask pattern; applying a mask membrane layer of a high X-ray transmissive material over said patterned thin layer; and removing at least a portion of the substrate to form an X-ray mask. 2. A method as defined in claim 1, further comprising the step of depositing an etch stop layer or a parting layer between said substrate and said thin layer to facilitate the removal of said substrate. 3. A method as defined in claim 2, further comprising the step of depositing a capping layer between said substrate and said etch stop layer or parting layer. 4. A method as defined in claim 1, further comprising the step of depositing an adhesion layer above and below said thin layer to promote adhesion of said thin layer to the adjacent layers. 5. A method as defined in claim 1, wherein said step of removing a portion of said substrate results in the retention of a portion of said substrate on peripheral sides of the X-ray mask. 6. A method as defined in claim 1, wherein said step of removing at least a portion of said substrate results in the removal of the entire substrate. 7. A method as defined in claim 6, further comprising the step of bonding a rigid support to said membrane layer, and wherein said step of removing a portion of said substrate is performed subsequently to the step of bonding of said rigid support. 8. A method as defined in claim 1, wherein said deposition of said thin layer is performed by vacuum deposition. 9. A method as defined in claim 1, wherein said step of applying a mask membrane layer comprises spinning a polimide film on said patterned layer.
	abstract	Systems and methods for storing spent nuclear fuel below grade that afford adequate ventilation of the spent fuel storage cavity. In one aspect, the invention is a system comprising: a shell forming a cavity for receiving a canister of spent nuclear fuel, at least a portion of the shell positioned below grade; and at least one inlet ventilation duct extending from an above grade inlet to a below grade outlet at or near a bottom of the cavity; the inlet ventilation duct connected to the shell so that the cavity is hermetically sealed to ingress of below grade fluids. In another aspect, the invention is a method comprising: providing a below grade hole; providing a system comprising a shell forming a cavity for receiving a canister of spent nuclear fuel, at least a portion of the shell positioned below grade, and at least one inlet ventilation duct extending from an inlet to an outlet at or near a bottom of the cavity, the inlet ventilation duct connected to the shell; positioning the apparatus in the hole so that the inlet of the inlet ventilation duct is above grade and the outlet of the inlet ventilation duct into the cavity is below grade; filling the hole with engineered fill; and lowering a spent fuel canister into the cavity.
	abstract	A method and an apparatus for deionizing water are disclosed. A condensate in the secondary cooling water system in a PWR nuclear power plant is passed through a mixture of an anion exchange resin and a cation exchange resin having a crosslinking degree of about 12 to 16%. The cation exchange resin has an improved, ion exchange capacity. thereby decreasing the frequency of changing the condensate.
	claims	1. A floor cleaner, comprising:an outer casing which forms a suction bell,an upper suction mouth on said casing,a pulling arrangement set on opposite sides of the casing, the pulling arrangement fitted with independent drive motors and corresponding transmission mechanisms on each side, andcleaning rollers, the cleaning rollers including:an assembly of interior cleaning rollers placed close to a center of the casing, and having a width substantially equal to a distance between lateral side elements of said casing, andan assembly of outer cleaning rollers placed in a zone close to front and rear edges of the casing of the cleaner, and having a total width greater than a width of said casing. 2. The floor cleaner, according to claim 1, wherein the suction mouth is provided with a rotary element joined to the casing. 3. The floor cleaner, according to claim 1, wherein the suction mouth is connected to an external source of suction. 4. The floor cleaner, according to claim 3, further comprising a body rotating at 45° with a lower element connected to the suction mouth and an upper element, and the upper element is fitted with a rotating mouth. 5. The floor cleaner, according to claim 1, wherein the casing also comprises an internal suction turbine. 6. The floor cleaner, according to claim 1, wherein the casing comprises a filter directly connected to the suction mouth. 7. The floor cleaner, according to claim 1, wherein movement of the outer cleaning rollers is independent from that of the interior cleaning rollers as well as of the drive motors and relevant transmission mechanisms. 8. The floor cleaner, according to claim 1, wherein movement of the outer cleaning rollers is synchronised with that of the interior cleaning rollers, all being moved by a single drive motor and corresponding transmission mechanisms. 9. The floor cleaner, according to claim 1, wherein the interior rollers are continuous, with a core made up of a single rigid body, and the drive mechanism is placed on at least one edge of the rigid body. 10. The floor cleaner, according to claim 1, wherein the exterior rollers are divided into two portions with a central drive mechanism, constituting a sole support for each of said portions. 11. The floor cleaner, according to claim 10, wherein the interior rollers are provided with one or more support wheels, moving along with the roller on which these are located. 12. The floor cleaner, according to claim 11, wherein the support wheels of the interior rollers are not aligned with the mechanism for driving the exterior rollers. 13. The floor cleaner, according to claim 10, wherein the interior rollers are provided with one or more support wheels, moving freely in respect of the roller on which these are located. 14. The floor cleaner, according to claim 1, wherein the rollers are made up of a core covered with a strip made of an elastic material constituting a cleaning brush, which comprises at least one set of lamellae set in a radial position on an outer surface thereof. 15. The floor cleaner, according to claim 1, wherein at least one of front ones of the exterior rollers and rear ones of the exterior rollers are fitted on an arm which is articulated in respect of the casing, and a hinge is provided with an elastic device returning them to a working position when this working position has been altered by the presence of an obstacle. 16. The floor cleaner, according to claim 1, further comprising a turbine for adherence to a support surface, which takes water from outside the bell and expels this water outside perpendicularly to the support surface. 17. The floor cleaner, according to claim 1, further comprising at least one light fixture. 18. The floor cleaner, according to claim 1, further comprising a camera for taking pictures. 19. The floor cleaner, according to claim 1, further comprising an electronic control system for control and governance with sealed connections. 20. The floor cleaner according to claim 19, wherein the electronic system for control and governance is made up of at least two elements, including a first element provided in the cleaner itself fitted with a connection system and another external element, which comprises the control system. 21. The floor cleaner, according to claim 20, wherein at least one of the elements is a computer. 22. The floor cleaner according to claim 19, wherein the electronic control system is duplicated, and includes one unit placed outside the cleaner, and connected by cables directly to the cleaner.
060752505	summary	FIELD OF THE INVENTION The present invention relates to a radiation image storage panel employable in a radiation image recording and reproducing method utilizing a stimulable phosphor. BACKGROUND THE INVENTION As a method replacing conventional radiography, a radiation image recording and reproducing method utilizing a stimulable phosphor was proposed and has been practically employed. In the method, a radiation image storage panel comprising a stimulable phosphor (i.e., stimulable phosphor sheet) is employed, and the method comprises the steps of causing the stimulable phosphor of the panel to absorb radiation energy having passed through an object or having radiated from an object; sequentially exciting the stimulable phosphor with an electromagnetic wave such as visible light or infrared rays (hereinafter referred to as "stimulating rays") to release the radiation energy stored in the phosphor as light emission (stimulated emission); photoelectrically detecting the light emission to obtain electric signals; and reproducing the radiation image of the object as a visible image from the electric signals. The radiation image storage panel thus treated is subjected to a step for erasing a radiation image remaining therein, and then is stored for the next radiation image recording and reproducing procedure. Thus, the radiation image storage panel can be repeatedly employed. In the radiation image recording and reproducing method, a radiation image is obtainable with a sufficient amount of information by applying radiation to an object at a considerably smaller dose, as compared with the conventional radiography using a combination of a radiographic film and a radiographic intensifying screen. The radiation image recording and reproducing method using a stimulable phosphor is of great value especially when the method is employed for medical diagnosis. The radiation image storage panel employed in the above-described method has a basic structure comprising a support and a stimulable phosphor layer provided on one surface of the support. The stimulable phosphor layer generally comprises stimulable phosphor particles and a binder polymer. Further, a transparent film of polymer material is generally provided on the free surface (i.e., surface not facing the support) of the phosphor layer to keep the phosphor layer from chemical deterioration or physical shock. As well as a phosphor layer comprising a binder and a stimulable phosphor dispersed therein, a phosphor layer formed by deposition process or firing process can be employed. The radiation image recording and reproducing method can be performed by means of an apparatus comprising: recording means (by which a radiation image is recorded on the panel), reading means (by which the radiation image recorded in the panel is read through the steps of exciting the stimulable phosphor with a stimulating ray to release stimulated emission and photoelectrically detecting the emission to read the recorded image), erasing means (by which the radiation image remaining on the panel is erased with erasing light), and conveying system connecting each means for conveying the panel. In such all-in-one type apparatus, the panel is repeatedly conveyed and repeatedly used. The above means may be separated into a recording apparatus comprising the recording means and a reading apparatus which has the reading means and the erasing means. In such case, the method is performed by a combination of the recording apparatus and the reading apparatus. The radiation image storage panel is repeatedly used in either case. In the radiation image recording and reproducing method, the radiation image recorded in the storage panel is generally read by applying the stimulating rays onto one surface side of the storage panel and collecting light emitted by the phosphor particles by means of a light-collecting means from the same side. However the light emitted by the phosphor particles may be collected on both sides of the radiation image storage panel. For instance, it may be the case that the emitted light is desired to be collected as much as possible. There also is a case that the radiation image recorded in the phosphor layer varies along the depth of the layer and such variation is desired to be detected. A typical radiation image reading system reading from both sides (hereinafter, referred to as "double-side reading system") is illustrated in the attached FIG. 1. In the FIG.1, the radiation image storage panel 11 is transferred (or moved) by a combination of two sets of nip rolls 12a, 12b. The stimulating rays such as laser beam 13 is applied onto the storage panel 11 on one side, and the light emitted by the phosphor particles in the storage panel advances upward and downward (in other words, to both the upper and lower surface sides). The downward advancing light 14a is collected by a light collector 15a (arranged on the lower side), converted into an electric signal in a photoelectric conversion device (e.g., photomultiplier) 16a, multiplied in multiplier 17a, and then sent to a signal processor 18. On the other hand, the upwardly advancing light 14b is directly, or after reflection on a mirror 19, collected by a light collector 15b (arranged on the upper side), converted into an electric signal in a photoelectric conversion device (e.g., photomultiplier) 16b, multiplied in multiplier 17b, and then sent to a signal processor 18. In the signal processor 18, the electric signals sent from the photoelectric conversion devices 17a, 17b are processed in a predetermined manner such as addition or reduction of the signals depending on the nature of the desired radiation image. The radiation image storage panel 11 is further moved by means of two sets of nip rolls 12a, 12b in the direction indicated by the arrow. The surface area of the panel on which the stimulating rays 13 have been applied is then set under a light source 20 such as a sodium lamp 20 for erasing an radiation image remaining in the storage panel 11. As is described above, the radiation image storage panel is repeatedly used in the cyclic procedure comprising the steps of exposing to a radiation (for recording of a radiation image), irradiating with stimulating rays (for reading of the recorded image) and exposing to an erasing light (for erasing the remaining image). The storage panel is transferred from one step to another step by means of conveying means such as belt and rolls, and after a cycle of steps is conducted, the panel is piled up on other panels and stored for next cycle. The radiation image storage panel used in the double-side reading system generally has a phosphor layer whose faces are covered with a transparent support (on the bottom side) and a transparent protective film (provided on the top side). However, the present inventors have found that such panel has a disadvantageous property: that is, the panel having been repeatedly used many times often gives relatively poor radiation images. For example, a ghost image is superimposed on the desired image, or noises have occurred which make the image quality poor. The inventors have studied the cause of production of poor radiation image and found the mechanism of the deterioration of the radiation image: that is, as the panel is repeatedly used, stains gradually deposit and abrasions are produced on the protective film and the back surface (surface not facing the phosphor layer) of the support, and therefore such stains and abrasions disturbs passages of the emitted light and make the image quality lower. With respect to the radiation image storage panel used in the single-side reading system, such deterioration is known and several improvements are proposed. In U.S. patent application Ser. No. 08/469,761 for example, the use of a protective film of a resin containing a fluororesin soluble in an organic solvent is proposed. Also proposed is a protective film made of a resin containing a film-forming resin and oligomer having a polysiloxane structure and/or having a perfluoroalkyl group in U.S. Pat. No. 5,227,253. U.S. patent application Ser. No. 08/834,772, now issued as U.S. Pat. No. 5,866,266, describes that a protective composite of a plastic film and a coated film of a fluororesin composition are placed on the phosphor layer. There is no knowledge, however, about the mechanism of deterioration of the radiation image given by the storage panel having been repeatedly used in the double-side reading system. SUMMARY OF THE INVENTION The present invention resides in a radiation image storage panel having a composite comprising a transparent support and a phosphor layer provided thereon containing stimulable phosphor particles, wherein the composite is covered on its both side surfaces (i.e., on the phosphor layer side surface and on the support side surface) with a protective film whose scratch resistance is higher than that of the surface of the support and whose contact angle is larger than that of the surface of the support. The "contact angle" and "scratch resistance", in the specification are determined by the following measurements: contact angle: methylene iodide is dropped onto a sample surface, and after 60 seconds the contact angle is measured; PA1 scratch resistance: a sample surface is scratched with a pencil and the scratch value is determined in accordance with JIS (i.e., Japanese industrial Standard). In the radiation image storage panel of the invention, the thickness of the protective film on the phosphor layer side surface is preferably smaller than that of the protective film on the back surface of the support.
	abstract	An illumination system for an extreme ultraviolet (EUV) lithography system may include multiple sources of EUV light. The system may combine the light from the multiple sources when illuminating a mask.
	description	This application is a continuation application of U.S. patent application Ser. No. 12/280,286, filed Jul. 7, 2010, which is a § 371 national stage entry of International Application No. PCT/US2007/062582, filed Feb. 22, 2007, which claims priority to U.S. Provisional Patent Application No. 60/775,736, filed Feb. 22, 2006, all of which are hereby incorporated by reference in their entirety. The invention relates to Pressurized Water Nuclear Reactors (PWNR) utilizing heat transfer fluids having nanoparticles dispersed therein for enhanced thermal transfer. A pressurized water Nuclear reactor (PWNR) has a core immersed in water in a large steel tank. The fuel rods and control rods make up a vertical array. The control rods are movable, and are pulled up above the fuel rods when the plant is in full operation. The purpose of the control rods is to absorb neutrons which trigger the splitting of atomic nuclei in the fissionable material in the fuel rods. With all the control rods inserted, there is negligible fission (and heating) in the fuel rods. When the control rods are pulled out the fuel rods heat the water, which is circulated by pumps in the primary or, inner loop, to a heat exchanger. A feature of this design is that only the water in the inner loop is in contact with the radioactive fuel rods. Thus, only the inner loop has contamination from the inevitable small amount of rust and corrosion. There are filters in this inner loop to capture the small particles which are radioactively contaminated. There are additional pumps to circulate cooling water through the core, which form the Emergency Core Cooling System (ECCS). It is essential that circulation be maintained to carry heat away from the fuel rods to prevent them from melting in the event that the main primary circulation pumps should fail. The water in the tank and the primary circulation loop is never supposed to boil, and thus always remain as water because steam is a much poorer conductor of heat as compared to water. The fuel rods are supposed to always stay under water. To prevent boiling, the tank and primary loop are maintained at very high pressure. The secondary loop water is heated through a heat exchanger with the primary loop. Water in the secondary loop is allowed to boil in a steam generator tank. The steam is used to drive a turbine which turns an electrical generator. The residual steam is condensed back to water, which is pumped back through the heat exchanger again to make more steam. Also, circulation usually through a large cooling tower which is used to remove the waste heat. One problem with conventional thermal transfer fluids used in PWNRs is the onset of a heat transfer condition that can lead to a departure from nuclei boiling (DNBR) that occurs at a condition call the critical heat flux. (CHF) which results in a blanketing of the fuel rod with bubbles that interferes with heat transfer and leads to a condition called dryout that can result in a critical failure of the fuel rods. What is needed is nanofluid having enhanced thermal transfer and stability for PWNRs to raise the heat flux level at which dryout condition will occur. This heat flux level is called the critical heat flux (CHF). A pressurized water nuclear reactor comprises a core comprising a containment shield surrounding a reactor vessel having fuel assemblies that contain fuel rods filled with fuel pellets and control rods, and a steam generator thermally coupled to the reactor vessel. A flow loop comprises the steam generator, a turbine, and a condenser, and a pump for circulating a water-based heat transfer fluid in the loop. The heat transfer fluid comprises a plurality of nanoparticles comprising at least one carbon allotrope or related carbon material dispersed therein. As used herein, the phrase “carbon allotrope or related carbon material” includes the carbon allotropes, such as diamond, graphite, lonsdaleite, fullerenes including C60, C540 and C70, amorphous carbon and carbon nanotube, and related materials including pyrolytic carbon, carbon black and diamond-like carbon. In some cases the allotrope or related material is functionalized, such as hydroxyl-functionalized fullerenes to promote dispersion in solution. The diamond particles are typically primarily colloidal and have a mean size of 0.5 nm to 200 nanometers. In other embodiments of the invention the mean particle size is 1 nm to 100 nm, such as 40 nm to 100 nm. A concentration of nanoparticles can range from 0.0001 to 10 volume percent of the heat transfer fluid, such as from 0.1 to 3 volume percent of the heat transfer fluid. A method of transferring heat using a heat transfer fluid comprises the steps of providing a water based heat transfer fluid comprising a plurality of carbon allotrope or related carbon material dispersed therein, placing the heat transfer fluid in a system comprising a coolant loop including a heat source and a heat sink, and circulating the heat transfer fluid in the coolant loop during operation of the system. The system can comprise a pressurized water nuclear reactor. A pressurized water nuclear reactor (PWNR) 100 comprises a core including a containment shield 105 surrounding a reactor vessel 110 having fuel assemblies that contain fuel rods filled with fuel pellets 115, and control rods 118, and a steam generator 120 thermally coupled to the reactor vessel 110. A flow loop includes the steam generator 120, a turbine 130, a condenser 135, and a pump 140 for circulating a water-based heat transfer fluid 145 in the loop. The heat transfer fluid 145 comprises a plurality of carbon allotrope or related carbon nanoparticles, such as diamond nanoparticles, dispersed therein. The turbine 130 is shown coupled to an electrical generator 150. Carbon allotropes are the different molecular configurations (allotropes) that pure carbon can take. The eight known allotropes of carbon include diamond, graphite, lonsdaleite, C60, C540, C70, amorphous carbon and carbon nanotube. Related essentially pure carbon related materials include pyrolytic carbon, carbon black, diamondoids (adamantanes) and diamond-like carbon. The present Inventors have found carbon allotrope and related carbon materials provide low neutron cross sections, stability under typical pressures and temperatures present in core of PWNR reactors, chemical stability in the chemical environment of a PWNR, and ability to remain dispersed in the heat transfer solution under typical pressure and temperature conditions. The carbon allotrope or related carbon material are preferably colloidal nanoparticles having a mean size of 0.5 nm to 200 nm, and are generally referred to herein as nanoparticles for convenient reference. The concentration of nanoparticles generally ranges from 0.0001 to 10 volume percent, such as 0.001, 0.01, 0.1, or 1%, of the total heat transfer fluid. The nanoparticles can be natural or synthetic, such as synthetic diamonds in the case of diamonds. Although the Examples provided herein relate only to stability of heat transfer fluids according to the invention, tests carried out indicate that inventive heat transfer fluids can defer the critical heat flux by up to about 50%. Thermal conductivity for heat transfer fluids according to the invention are also expected to be about 150% over conventional PWNR water. Other notable features regarding allotropic carbon or related carbon comprising nanoparticle comprising thermal transfer fluids according to the invention include: a.) Toleration of extreme environments: i. Temperatures ranging from the solidification point of the base fluid to the supercritical point of the base fluid; ii. Pressures ranging from 1-10,000 psi; iii. Flow rates ranging from 0-10 m/s; and iv. Radioactive environment such as the core of a Pressurized Water Nuclear Reactor. b.) Both nanoparticle size and concentration can be low enough to render the heat transfer fluid non-abrasive to the components of the application, including but not limited to PWNR components such as pumps, Zircaloys (a group of high-zirconium alloys), stainless steel piping, etc. Non-abrasive, as used herein, refers to no detection of erosion debris after 6 months (or more) under simulated reactor conditions. c.) The low neutron capture capability provided allows application in the core of a PWNR which decreases the critical heat flux (CHF) in a PWNR. It should be understood that the examples described below are provided for illustrative purposes only and do not in any way define the scope of the invention. For example, although the Examples all utilize diamond nanoparticles, as noted above the dispersed nanoparticles can be any of the carbon allotropes or related carbon materials. The present Inventors determined that the extent to which nanoparticles retain their size following exposure to PWNR autoclave conditions can provide a measure of particle stability in a nuclear reactor environment. The effect of 24 hours under simulated PWNR conditions on particle size was evaluated. Particle size distributions were first collected for all samples prior to the autoclave runs. The samples were then taken to the autoclave, and were run at approximately 630° F. and 2500 psi for 24 hours. The composition of the low boron samples for all experiments described below was 1.6 ppm LiOH and 42.7 ppm boric acid. The composition of the high boron samples for all experiments described below was 1.6 ppm LiOH and 1400 ppm boric acid. A. Beckman-Coulter LS13320: A Beckman-Coulter LS13320 laser diffraction size analyzer was used to investigate the effect of PWNR conditions on particle size distribution. The laser diffraction size analyzer utilizes a laser diffraction method for analyzing particle size distribution and measures particle sizes from 40 nm to 2,000 μm. Advantages of laser diffraction include simplicity of operation, a built in mixer to keep particles dispersed and a broad dynamic size range encompassing the nano region from 40 nm up through 2 millimeters. Thus both primary particles and agglomerates can be observed simultaneously giving an indication of the relative state of agglomeration. FIG. 2 shows the volume distribution of the as received diamond particle samples dispersed in the simulated water chemistry of beginning of cycle reactor fluid. Conditions were low boron conditions comprising 1.6 ppm LiOH and 42.7 ppm boric acid and a pH of 6.9. The volume plot shown in FIG. 2 indicates that only 20% of the diamond nanoparticles were well dispersed before autoclaving and this proportion appeared to increase slightly after PWNR conditions. There was also some growth in size of agglomerates in all runs. In both cases, the dispersed diamond fraction maintained a consistent size (number basis) in the vicinity of 75 nanometers (0.075 μm). The results were similar for the high boron (beginning of cycle shown in FIG. 3) water chemistry and for the 500 hour low boron diamond run shown in FIG. 4. B. Microtrac UPA 150 A Microtrac UPA 150 was used to better characterize particle size distributions in the nanometer range. The UPA 150 (Ultra-fine Particle Analyzer) is a dynamic light scattering method, and provides particle size and the size distribution from approximately 0.003 μm to 6.54 μm. The Microtrac is designed to quantify nanoparticle dispersions only up to a few microns and therefore cannot detect the fraction of large agglomerated material, which settles rapidly out of the detection volume in the unstirred 20 ml sample cell. Thus it provides a good representation of the dispersed fraction of material. FIGS. 5 and 6 represent UPA 150 volume distributions for 1 wt % diamond (high boron content) in water after 24 hour autoclave at 275 C/2500 psi on the diamond powder at low boron (EOC) and high boron (BOC) concentrations, respectively. The results are consistent with the laser diffraction data and show a low tendency towards agglomeration. FIG. 7 shows UPA 150 volume distributions for 1 wt % diamond (high boron content) in water before and after a 500 hour run at EOC conditions which suggests that there may be some tendency to agglomerate at longer exposure periods. However, the reactor used for the tests was a static reactor with no stirring or circulation to promote dispersion agglomeration. Accordingly, agglomeration can likely be significantly reduced by including the reactor with a means for stirring or circulation to promote dispersion. C. BET Surface Area: A Brunauer-Emmett-Teller (BET) surface area analyzer estimates the specific external surface of a solid by determining the volume of a specific gas that is absorbed under controlled conditions. BET surface area was measured using a Quantachrome NOVA 1200 Surface Area Analyzer to analyze any changes in specific surface area in diamond due to 24 hours at PWNR conditions. This instrument performs rapid and accurate sorption measurements of nitrogen gas on particle surfaces to directly measure surface area. Prior to gas adsorption, the powder sample was degassed and dried in a vacuum at a temperature of 180° C. Measurements made by this instrument include multipoint BET method surface area, single point BET surface area, 25 point adsorption isotherms, 25 point desorption isotherms, total pore volume, average pore radius, and BJH pore size distribution based on the adsorption or desorption isotherm. FIG. 8 shows a typical BET straight line plot for as-received diamond powder. Table 1 (below) shows BET data for the 24 hour autoclave runs and the single 500 hour autoclave run on the diamond sample. BET surface area measurements are normally reproducible to within 5%. The data in table one indicates some degradation of surface area after autoclaving with the largest decrease (.about.15%) observed for the 500 hour run. The formula for calculating the geometric diameter of a sphere from the specific surface area is: d microns = 6 ρ ⁡ ( g / cm 3 ) × S . S . A . ( m 2 / g ) where d is the diameter in microns, ρ is the density in g/cm3 and S.S.A. For the diamond, the as-received surface area of 97.7 m2/g, equates to a spherical equivalent diameter of 17.8 nanometers (ρ=3.45) which is far smaller than the measured mean particle size. This discrepancy is consistent with the large relatively hard agglomerates which are made up of the primary nanoparticles. These provide microporous interparticle spacing in which the nitrogen can condensed during analysis. In addition, the manufacturer has indicated that the particles are engineered with surface features (microcracks) that may enhance nitrogen adsorption. The bulk of the decrease in surface area for the 500 hour runs is likely to occur inside these diamond agglomerates. TABLE 1BET surface area for diamond runs.BETSample IDSurface areaCorrelationAs Received Diamond105.5.9980As Received Diamond90.1.999844 (high boron) Before autoclaving (as105.8.9998received)38 (low boron) After autoclaving 24 hrs98.28.999039 (low boron) After autoclaving 24 hrs103.0.995340 (low boron) After autoclaving 24 hrs87.5.999941 (low boron) After autoclaving 500 hrs85.8.999144 (high boron) After autoclaving 24 hrs104.4.9998D. Zeta Potential Brookhaven Instruments The zeta potential of the nanoparticulates was measured by the electrophoretic mobility method using photon correlation spectroscopy. For most ensemble size measurements techniques what is really measured is the agglomerate size distribution. Thus, the size distribution is highly dependent on the state of dispersion of the system. Any ensemble particle size measurement must be interpreted in this context. Due to attractive forces (Van der Waals, and other), particles will tend to agglomerate in suspension unless stabilized by surface charge or steric effects. Most aqueous suspensions of hydrophilic powders will specifically adsorb or desorb hydrogen ions to generate a surface charge. Homogeneous powders that develop a surface charge high enough to overcome interparticle attraction will form more stable dispersions. The point of zero charge is approximated by measuring the isoelectric point—that is, the pH at which the zeta potential is zero. The pH at which this occurs is material dependent. For a native diamond oxide surface the isoelectric point tends to be low. The charge is more positive as the pH (acidic solutions) decrease below the isoelectric point and more negative as the pH rises above the IEP. The closer the pH is to the isoelectric point the greater the tendency for the material to agglomerate. Table 2 shows the zeta potential for the diamond both before and after autoclave treatment. In general the diamond displays a relatively high negative zeta potential under all conditions tested. The zeta potential was significantly lower in the high boron containing sample (BOC) to the higher ionic strength of the solution (10 times greater than EOC samples). This is expected, as high ionic strength tends to suppress the double layer and reduce the zeta potential. The zeta potential was the highest for the 500 hour autoclave (EOC conditions) run. This bodes well for the stability of diamond nanopowder dispersions under these conditions. TABLE 2Zeta potential measurements for diamond runs before andafter autoclaving.Zeta PotentialStandardSample(mV)ErrorpH24 hour Low Boron (before)−34.110.826.7-6.824 hour Low Boron (after)−28.9 0.876.7524 hour High Boron #44 (before)−16.16/−24.91.05/6.8224 hour High Boron #44 (after)−20.8 1.756.82500 hour Low Boron #41 (before)−28.850.926.73500 hour Low Boron #41 (after)−26.250.836.76500 hour Low Boron #41 (after)−39.5 1.096.8 E. JEOL 3035 Field Emission SEM and JEOL-2010F Scanning TEM: Diamond surface morphology was examined using both SEM and TEM. Scanning electron microscopy revealed very large particles appearing to be fractured bulk material. Further testing, discussions with the manufacturer and TEM indicated that these particles actually were hard porous agglomerates of the about 75 nm average primary particles. The fracture surfaces most likely are the results of the manufacturer grinding the pan dried nanomaterial for packaging. These agglomerates were impossible to redisperse in their entirety. High energy sonication produced an average of 20% dispersion (by mass) into the desired nano particle size. The remaining 80% stayed agglomerated even through simulated PWNR conditions. TEM analysis was performed on the nanodispersed phase. Scanned images taken with TEM for a sample of diamond not exposed and after exposure to PWNR conditions. The diamond morphology did not appear to be significantly affected by exposure to PWNR conditions. F. X-Ray Diffraction (XRD): X-ray diffraction measurements were conducted on powders before and after autoclaving at PWNR conditions to determine if any changes could be observed in crystal structure. For the diamond, no changes were noted between the as received and post treatment samples. FIGS. 9-11 show the as-received powder (dried but not rinsed), and the 500 hour low boron autoclaved diamond, respectively. The powders were dried and analyzed directly from the reactor water without rinsing to avoid loss of potential nanoparticulate phases. Consequently, crystallized soluble (lithium borate hydrates) species are apparent in spectra, particularly the high boron (BOC) samples. No graphitic peaks (2.theta.=26.53/100, 44.63/50, 54.70/80) or other carbon phases were observed. G. FTIR and RAMAN Spectroscopy: In addition, the three diamond samples were analyzed with FTIR and with RAMAN spectroscopy. These instruments can be used to identify differences in the functional groups present on the surface and in the bulk for many materials including gases, liquids, solids, fibers, and thin films. RAMAN was used to observe changes in the surface chemistry of the material during the autoclave run. Micro-RAMAN spectra obtained evidenced how little the Raman spectra changes during the low boron autoclave run. The RAMAN intensities are quite low, and the peaks are not sharp. However, there appears to be little change after exposure to PWNR conditions. These are typical results for the low boron runs. RAMAN was not performed on the high boron or 500 hour runs. The FTIR spectra of these powders gives a better indication of the surface composition of the nano diamond powders. A diffuse reflectance sampling apparatus (Gemini, Spectra Tech) was used to maximize the amount of surface information. The spectra of the initial powder and that of the three low boron replicates prior to autoclaving were obtained. (Thus the powder was suspended, then dried at about 100 degrees Celsius for about 1 h. It was diluted with dry potassium bromide at about 1 weight percent prior to analysis.) These powders all exhibited peaks in the 3700-2700 cm−1 range typically associated with hydroxyl bonds. There is a strong peak at about 1720 cm−1 which (along with others) indicates the presence of carboxylic acid groups. The peak at about 1615 cm−1 is probably due to aromatic carbon-carbon double bonds. In short, the features shown are typical of a partially oxidized carbon surface. The FTIR spectra for the nanodiamond powder do show some minor differences after exposure to PWNR conditions. The IR spectra of the nanodiamond powder (EOC) dried from solution both before and after exposure in the autoclave revealed several differences. The hydroxyl peak (about 3000-3700 cm−1) is slightly reduced in intensity and the CH stretching peaks around 2800-3000 cm−1 increase in intensity. Small peaks at about 1520 and 760 cm−1 also form. The results disclosed above indicate that the diamond comprising thermal transfer system provides a high level of dispersion stability. Chemical stability of the diamond appears excellent, although higher quality diamond nanopowders may provide even better results. All nanopowders are preferably obtained in an aqueous dispersed state when possible. The dispersion stability of diamond also appears quite good. It is to be understood that while the invention has been described in conjunction with the preferred specific embodiments thereof, that the foregoing description as well as the examples which follow are intended to illustrate and not limit the scope of the invention. Other aspects, advantages and modifications within the scope of the invention will be apparent to those skilled in the art to which the invention pertains.
050680803	abstract	The present invention is a computer based system supporting plant operators in caring out nearly routine operations. The computer based system monitors available plant instrumentation signals and processes the gathered information to detect satisfaction of initial conditions to the state change. Once the state change is started, the system then compares the sequence of observed changes in the plant with a preprogrammed sequence and alerts the operators to any undesirable deviations from the preplanned sequence by providing appropriate attention grabbing displays on a system monitor. The system also continuously monitors constraining conditions and alerts the operator when the system moves toward an undesired state. The system requires no input from the operator when the operation underway is following the prescribed sequence and minimal input from the operator when a deviation is detected. The system internally and automatically tracks the evolution of plant states during the nearly routine operations.
056129831	summary	FIELD OF THE INVENTION This invention relates to a device for filtering water to at least one emergency cooling system in a nuclear power plant of the type comprising a reactor arranged in a containment which substantially consists of an upright, suitably cylindrical container whose bottom part forms a pool for collecting water formed by condensation of steam present in the containment, the condensation pool including a number of back-flushable strainers serving to filter water which is taken from the pool and, if required, is supplied to nozzles in the emergency cooling system in order to cool the reactor core in the event of an inadmissible temperature rise therein, each strainer having the shape of a housing with at least one, suitably cylindrical, apertured strainer wall through which the water can flow from the outside and into the housing, and being connected, by a first conduit passing through the container wall, to a suction pump disposed outside the container wall, as well as connected to a second conduit for supplying wash water to the interior of the housing in order, if required, to flush the strainer wall by flowing the wash water through it from the inside and out, thereby removing filtrate deposited on the outside of the strainer wall. BACKGROUND OF THE INVENTION In actual practice, the above-mentioned emergency cooling system consists of a first sprinkler system comprising a plurality of nozzles or sprinklers mounted in the upper part of the reactor and adapted to spray large amounts of water on the fuel rods in order to cool these when there is an emergency. The plant further includes a second sprinkler system comprising a plurality of nozzles or sprinklers which, like those of the first system, take their water from the condensation pool in the containment, but which are mounted outside the reactor proper and are adapted to sprinkle the gas phase in the containment in order to reduce any remaining excess pressure therein as well as to cool conduits or other components found inside the containment but outside the reactor itself. In both instances, it is of great importance that the water supplied to the nozzles is free from all sorts of impurities, such as fibres, grains and particles, that might clog the nozzles. Naturally, this is especially important in the emergency cooling system, which has to be absolutely reliable. Many of the components mounted inside the containment, such as the conduits, are wholly or partly heat insulated. In most of today's nuclear power plants, this insulation is made up of fibres of mineral wool, which constitute an element of risk with regard to the two sprinkler systems, in that unintentionally released fibres may clog the nozzles if reaching the sprinkler systems. For this reason, nuclear power plants have been equipped with strainers of the type stated by way of introduction. Existing back-flushable strainers are mounted on the inside of the cylindrical container wall of the containment. This wall is made up of a thick, resistant concrete wall and a lining in the form of non-corrosive sheet-metal applied on the inside of the wall, ensuring absolute liquid proofness between the inside and the outside of the containment. The strainers are mounted by means of a number of attachments anchored in the concrete by bolts or dowels carefully sealed where they pass through the sheet-metal lining. In actual practice, it takes about 5-10 min to back-flush a strainer which is contaminated with a fibre mat tending to clog the strainer holes. It was previously held that the strainers could operate for at least 10 h without any need of back-flushing. However, real-life incidents have shown that this estimated minimum operating time is too long. In functional tests, it has happened that discharged steam has entrained mineral-wool insulation, which has dropped into the condensation pool and clogged the strainers even after about 30 min. Back-flushing, which takes 5-10 min, is not a critical operation 10 h after a possible reactor trip, since the decay power of the reactor core then has been considerably reduced, as has the need for cooling. However, if back-flushing is required after less than 1 h, the need for cooling of the core is still considerable, and an interruption of the water supply to the emergency cooling system therefore is unacceptable for reasons of safety. An obvious solution would of course be to increase the area of the strainers. In theory, this could be done by replacing the existing back-flushable strainers with larger ones, i.e. having enlarged apertured strainer walls. However, such replacement strainers of enlarged diameter would be disadvantageous not only by being difficult to introduce into the containment through extremely narrow passages, but also by running the risk of being exposed to excessive mechanical forces when the water in the condensation pool is heaving when steam is blown into the containment. SUMMARY OF THE INVENTION This invention aims at providing a solution to this problem which can be implemented in expedient and reliable fashion. Thus, a basic object of the invention is to enable the installation, in existing plants, of additional strainers that can be introduced into the containment through narrow passages without difficulty. Another object of the invention is to enable expedient mounting of the additional strainers, so that these can be mounted in an existing plant in extremely short time, thus minimising the stoppage required. A further object of the invention is to provide an improved back-flushable strainer. At least the basic object of the invention is achieved by a device having the features recited in the characterising clause of appended claim 1.
	claims	1. A method of removing detector cables from a nuclear reactor using an instrument removal system comprising a removal cart and a disposal cask, the removal cart comprising a base, a plurality of wheels coupled to the base, a motor mounted on the base, a drive shaft operatively coupled to the motor, a disposal spool removably mounted on the drive shaft, a notch in the disposal spool sized to receive the detector cable, a housing mounted on the base that encloses the disposal spool, an entrance port in the housing sized to permit the detector cable to enter the housing, the reactor comprising a pressure vessel, an under vessel platform, and a plurality of transfer rails, said method comprising:positioning the removal cart and the disposal cask under the reactor pressure vessel;attaching the detector cable to the disposal spool;winding the detector cable onto the disposal spool;transferring the disposal spool to the disposal cask; andmoving the disposal cask from under the reactor pressure vessel. 2. A method in accordance with claim 1 wherein attaching the detector cable comprises inserting the detector cable into the notch in the disposal spool. 3. A method in accordance with claim 1 wherein winding the detector cable onto the disposal spool comprises activating the motor to turn the drive shaft and the disposal spool. 4. A method in accordance with claim 1 wherein the disposal cask comprises a main body having a cavity therein sized to receive at least one disposal spool, an access door in the main body that permits access to the cavity when the access door is in an open position, and a plurality of wheels operatively coupled to the main body, the removal cart further comprising a housing door and at least one air piston mounted in a bearing block attached to the base; andtransferring the disposal spool to the disposal cask comprises activating the at least one air piston to extend and push the disposal spool off the drive shaft and out the housing door into the disposal cask. 5. A method in accordance with claim 4 wherein moving the disposal cask from under the reactor pressure vessel comprises rolling the disposal cask along the transfer rails on the disposal cask wheels. 6. A method of removing detector cables from a nuclear reactor, the reactor comprising a pressure vessel, an under vessel platform, and a plurality of transfer rails, said method comprising:providing an instrument removal system, the instrument removal system comprising:a removal cart and a disposal cask, the removal cart comprising a base, a plurality of wheels coupled to the base, a motor mounted on the base, a drive shaft operatively coupled to the motor, a disposal spool removably mounted on the drive shaft, a notch in the disposal spool sized to receive the detector cable, a housing mounted on the base that encloses the disposal spool, an entrance port in the housing sized to permit the detector cable to enter the housing;positioning the removal cart and the disposal cask under the reactor pressure vessel with the removal cart wheels riding on the transfer rails;attaching the detector cable to the disposal spool;winding the detector cable onto the disposal spool;transferring the disposal spool to the disposal cask; andmoving the disposal cask from under the reactor pressure vessel. 7. A method in accordance with claim 6 wherein attaching the detector cable comprises inserting the detector cable into the notch in the disposal spool. 8. A method in accordance with claim 6 wherein winding the detector cable onto the disposal spool comprises activating the motor to turn the drive shaft and the disposal spool. 9. A method in accordance with claim 6 wherein the disposal cask comprises a main body having a cavity therein sized to receive at least one disposal spool, an access door in the main body that permits access to the cavity when the access door is in an open position, and a plurality of wheels operatively coupled to the main body, the removal cart further comprising a housing and at least one air piston mounted in a bearing block attached to the base; andtransferring the disposal spool to the disposal cask comprises activating the at least one air piston to extend and push the disposal spool off the drive shaft and out the housing door into the disposal cask. 10. A method in accordance with claim 9 wherein moving the disposal cask from under the reactor pressure vessel comprises rolling the disposal cask along the transfer rails on the disposal cask wheels. 11. A method of removing detector cables from a nuclear reactor, the reactor comprising a pressure vessel, an under vessel platform, and a plurality of transfer rails, said method comprising:providing an instrument removal system, the instrument removal system comprising:a removal cart and a disposal cask, the removal cart comprising:a base, a plurality of wheels coupled to the base, a motor mounted on the base, a drive shaft operatively coupled to the motor, a disposal spool removably mounted on the drive shaft, a notch in the disposal spool sized to receive the detector cable, a housing mounted on the base that encloses the disposal spool, an entrance port in the housing sized to permit the detector cable to enter the housing, the disposal cask comprising:a main body having a cavity therein sized to receive at least one disposal spool, an access door in the main body that permits access to the cavity when the access door is in an open position, and a plurality of wheels operatively coupled to the main body;positioning the removal cart and the disposal cask under the reactor pressure vessel with the removal cart wheels and the disposal cask wheels riding on the transfer rails;attaching the detector cable to the disposal spool;winding the detector cable onto the disposal spool;transferring the disposal spool to the disposal cask; andmoving the disposal cask from under the reactor pressure vessel. 12. A method in accordance with claim 11 wherein attaching the detector cable comprises inserting the detector cable into the notch in the disposal spool. 13. A method in accordance with claim 11 wherein winding the detector cable onto the disposal spool comprises activating the motor to turn the drive shaft and the disposal spool. 14. A method in accordance with claim 11 wherein the removal cart further comprises a housing and at least one air piston mounted in a bearing block attached to the base; andtransferring the disposal spool to the disposal cask comprises activating the at least one air piston to extend and push the disposal spool off the drive shaft and out the housing door into the disposal cask. 15. A method in accordance with claim 11 wherein moving the disposal cask from under the reactor pressure vessel comprises rolling the disposal cask along the transfer rails on the disposal cask wheels.
	description	The present invention relates to an improved sensor for use with an ion implanter that reduces production rate of material from the Faraday, thus lowering the deposition rate in the process chamber and thereby lowering the frequency of required maintenance. Ion implanters can be used to treat silicon wafers by bombardment of the wafers with an ion beam. One use of such beam treatment is to selectively dope the wafers with impurities of a controlled concentration to yield a semiconductor material during fabrication of a integrated circuits. A typical ion implanter includes an ion source, an ion extraction device, a mass analysis device, a beam transport device and a wafer processing device. The ion source generates ions of desired atomic or molecular dopant species. These ions are extracted from the source by an extraction system, typically a set of electrodes that energize and direct the flow of ions from the source. The desired ions are separated from byproducts of the ion source in a mass analysis device, typically a magnetic dipole performing mass dispersion of the extracted ion beam. The beam transport device, typically a vacuum system containing an optical train of focusing devices transports the ion beam to the wafer processing device while maintaining desired optical properties of the ion beam. Finally, semiconductor wafers are implanted in the wafer processing device. Batch processing ion implanters include a spinning disk support for moving multiple silicon wafers through the ion beam. The ion beam impacts the wafer surface as the support rotates the wafers through the ion beam. Serial implanters treat one wafer at a time. The wafers are supported in a cassette and are withdrawn one at time and placed on a support. The wafer is then oriented in an implantation orientation so that the ion beam strikes the single wafer. These serial implanters use beam shaping electronics to deflect the beam from its initial trajectory and often are used in conjunction with co-ordinated wafer support movements to selectively dope or treat the entire wafer surface. Faraday cups are used to measure beam current. These cups are periodically inserted into an ion beam either upstream of the implantation chamber or at a region behind a workpiece support to monitor beam current. U.S. Pat. No. 6,992,309 to Petry et al. illustrates a dosimetry system having a Faraday cup that is mounted for movement along a controlled path. The disclosure of the '309 patent is incorporated herein by reference. A semiconductor processing tool has an evacuated region for treating a workpiece by directing an ion beam to strike a workpiece. One such tool includes an ion source and beam transfer structure for transferring ions in a beam from the ion source to a workpiece support. The workpiece support is located in an implantation chamber. The path of travel from the source to the implantation chamber is at a low pressure as is the implantation chamber. A sensor includes an electrically conductive base and a mask electrically coupled to the conductive base that divides ion that make up an ion beam into regions or segments. The mask has walls extending from a front region of the sensor to the base. These walls impedes ions that reach the sensor from reentering the evacuated region of the processing tool. Further features of the disclosure will become apparent to those skilled in the art to which the present invention relates from reading the following specification with reference to the accompanying drawings. Turning to the drawings, FIG. 1 is a schematic depiction of an ion beam implanter 10. The implanter includes an ion source 12 for creating ions that form an ion beam 14 which is shaped and selectively deflected to traverse a beam path to an end or implantation station 20. The implantation station includes a vacuum or implantation chamber 22 defining an interior region in which a workpiece such as a semiconductor wafer is positioned for implantation by ions that make up the ion beam 14. Control electronics (FIG. 8) are provided for monitoring and controlling the ion dose received by the workpiece in the implantation chamber. Operator input to the control electronics are performed via a user control console (not shown) located near the implantation station 20. The ions in the ion beam 14 tend to diverge as the beam traverses a region between the source and the implantation chamber. To reduce this divergence, the region is maintained at low pressure by one or more vacuum pumps 27 in fluid communication with the ion beam path. The ion source 12 includes a plasma chamber defining an interior region into which source materials are injected. The source materials may include an ionizable gas or vaporized source material. Ions generated within the plasma chamber are extracted from the chamber by ion beam extraction assembly 28, which includes a number of metallic electrodes for creating an ion accelerating electric field. Positioned along the beam path 14 is an analyzing magnet 30 which bends the ion beam 14 and directs the ions through a beam neutralizer 32. The beam neutralizer injects electrons into the beam and impedes beam blow up thereby enhancing the ion transfer efficiency of the system. Downstream form the neutralizer 32, the beam 14 passes through a resolving aperture 36 which is an aperture plate which defines a minimum beam waist. The ion beam 14 that exits the resolving aperture is of an appropriate size and shape for the application. A workpiece support 40 known as wafer clamp is seen position in relation to a port 42 in fluid communication with a pump (not shown). A wafer is electrostatically attracted to the support and rotates the wafer up into the beam and then moves the workpiece up and down and from side to side with respect to the ion beam 14. The sequence of movements is such that an entire implantation surface of the workpiece 24 is uniformly implanted with ions. A typical application treats a wafer to dope the wafer with controlled concentrations of dopant. Since the implantation chamber interior region is evacuated, workpieces must enter and exit the chamber through a load lock 50. In accordance with one embodiment, a robot that is positioned within the implantation chamber 22 moves wafer workpieces to and from the load lock. The robot moves the wafer from the load lock to the workpiece support by means of an arm which reaches into the load lock to capture a workpiece for movement within the evacuated region of the implantation chamber. Prior to implantation, the workpiece support structure rotates the workpiece to a vertical or near vertical position for implantation. If the workpiece 24 is vertical, that is, normal with respect to the ion beam 14, the implantation angle or angle of incidence between the ion beam and the normal to the workpiece surface is 0 degrees. In a typical implantation operation, undoped workpieces (typically semiconductor wafers) are retrieved from one of a number of cassettes by a robot outside the chamber which move a workpiece which has been oriented to a proper orientation into the load lock. The load lock closes and is pumped down to a desired vacuum, and then opens into the implantation chamber 22. The robotic arm of the chamber robot grasps the workpiece 24, brings it within the implantation chamber 22 and places it on an electrostatic clamp or chuck of the workpiece support structure. The electrostatic clamp is energized to hold the workpiece 24 in place during implantation. Suitable electrostatic clamps are disclosed in U.S. Pat. No. 5,436,790, issued to Blake et al. on Jul. 25, 1995 and U.S. Pat. No. 5,444,597, issued to Blake et al. on Aug. 22, 1995, both of which are assigned to the assignee of the present invention. Both the '790 and '597 patents are incorporated herein in their respective entireties by reference. After ion beam processing of the workpiece 24, the workpiece support structure returns the workpiece 24 to a horizontal orientation and the electrostatic clamp releases the workpiece. The chamber robot grasps the workpiece after such ion beam treatment and moves it from the support back into the load lock. From the load lock, a robotic arm of a robot outside the chamber 22 moves the implanted workpiece 24 back to one of a storage cassette and most typically to the cassette from which it was initially withdrawn. Faraday Cup A Faraday cup sensor 110 is mounted to an interior wall of the ion implantation chamber 22 at a region 112 behind the workpiece support 40. The sensor 110 is shown in the exploded perspective view shown in FIG. 2 to include an electrically conductive base 120 and a mask structure 122 in electrical engagement with the conductive base 120. The mask 122 divides the incident ion beam, sending it into multiple pathways 130a, 130b, 130c etc (FIG. 5) leading to the base 120 that are bounded by intermediate walls 132, essentially making many very deep Faraday cups in close proximity. The walls extend from a front edge or entrance 134 of the mask to the base 120. The walls 132 impede ions in the beam from bouncing off the base and reentering the evacuated region of the processing tool. The walls 132 also serve to impede material dislodged from the base from being ejected from the Faraday cup sensor 110 into the ion implantation chamber 22. The Faraday cup sensor 110 includes a front or entrance plate 140 that provides an interior border 142 surrounding the beam which allows ions passing through the implantation region of the chamber to impact the mask/base combination. A number of magnets 150 are mounted between the mask 122 and the entrance plate 140. These magnets 150 are mounted to a rectangular shaped magnet support 152. The magnets prevent electrons created as ions impact the base or mask from backstreaming into the implantation chamber 22. The magnetic field that is created by the magnets is generally uniform in a gap 154 between the magnets and deflects electrons to the side. An electron in this region is deflected to the side walls of the Faraday cup 156. The base 120 supports the mask 122 in position relative the ion beam and includes side walls 156 and a rear wall 157 that define a cup that bounds the mask and fit inside the magnet support 152 and a housing 160 for the sensor 110. The housing defines bosses 162 at its corners that have threaded openings to accommodate corresponding threaded connectors which pass through openings in the entrance plate 140 on a surface facing away from the walls of the chamber 22. Similar threaded openings in these bosses 162 facing toward the walls of the chamber mate with connectors passing through a mounting plate 164 that attaches the sensor to the inner walls of the chamber. Water is routed into the region of the sensor 110 by inlet and outlet conduits 166, 167 which direct coolant (typically water) into and out of a heat sink 170 that defines passageways for routing the coolant through a heat absorbing portion 172 of the heat sink 170 that abuts a back wall 174 of the base 120. As seen most clearly in FIG. 5, fluid connectors 176 attach to the heat sink 170 and extends through an opening 180 in the mounting plate 164. Quick disconnect couplings are easily connected and disconnected at a point outside the chamber at atmospheric pressure. Some ion implant recipes call for angled implants. To meet these requirements the process chamber 22 rotates about a vertical axis, changing the angle of the workpiece relative to the ion beam. To maintain the advantages of the mask, even at high implant angles, a second region of the Faraday structure has been made at an angle. As seen most clearly in FIG. 5, the mask has two side by side portions P1, P2. These are shown to depict two alternate mask configurations. In an alternate arrangement all passageways are of the same configuration. There is nothing in the operation of the sensor, however, that would preclude use of the alternate designs in a single mask. On the left (as seen in FIG. 5) the mask defines passageways 130a, 130b etc that provide an unimpeded path for ions to the base. On the right, the passageways 190a, 190b etc are bounded by walls 192 that are angled with respect to the front surface 134 (approx 30-35 degrees) of the mask. This angle was chosen as it provides the best results for the given geometry over the widest range of high implant angles. Turning to FIG. 1, the entire implant chamber 22 rotates, along with the support 40 about a y axis approximately co-incident with the position of the workpiece. This allows the angle of incidence between the beam 14 and the wafer workpiece to be adjusted. As this rotation occurs the sensor 110 revolves to a different position. As seen in FIG. 5, when the incident angle between beam 14 and workpiece is at right angles, the beam (with the support 40 out of the way) strikes the sensor 110 at a position on the left of the sensor portion P1. When the chamber is rotated to its extreme counterclockwise position, the beam strikes the portion P2 along the right of that portion. Although two different portions are depicted it is appreciated that more than two different angles could be used and that for example a continuum of angles across a width of the mask could be used. In the exemplary embodiment both the mask and the base are fabricated from graphite. The two are held in electrical contact and the current due to ion bombardment is routed to ground through a conductor 210 attached to the sensor 110. A variable gain current sensor having two amplifiers 212, 214 monitors current through this conductor 210 and converts the current to a voltage. An output from the current sensor is coupled to an A/D converter 216 and indicates to the controller 220 the magnitude of the current which is used in adjusting ion beam parameters to control a dose of ion implantation when the support positions a wafer workpiece in the beam for implantation treatment. An optimization between minimizing frontal surface area and maximizing the depth to diameter aspect ratio of the passageways yields the most efficient structure. Constraints such as physical room in the tool, manufacturability, material choice and material properties, play a crucial roll in this optimization. Circular passageways that have generally cylindrical walls are preferred due to the ease of manufacturing. Hexagonal configurations may be more efficient in gathering ions but are harder to construct. Square configurations may be easier to construct but less efficient. A goal is to maximize ion capture as well as limiting backscattering without undue encroachment in the region of the chamber 22. The specific geometry, material choice and application will determine the optimal dimensions of the mask structure. It is understood that although an exemplary embodiment of the invention has been described with a degree of particularity, alterations and modifications from that embodiment are included which fall within the spirit or scope of the appended claims.
	abstract	A human phantom apparatus is provided with a body section, a head section connected with the body section, at least one shoulder section connected with the body section, and an arm section including a hand section, the arm section connected with the shoulder section. Each of the body section, the head section, the at least one shoulder section, and the arm section is filled with a human body equivalent material. The human phantom apparatus has a so-called PDA (Portable Digital Assistance) attitude of holding a radio communication apparatus by the hand section of the arm section, so that the human phantom apparatus looks at a display unit of the radio communication apparatus in front of the body section.
	description	The invention relates to the field of irradiation processing using an electron beam, and more particularly, to a device and a method for optimizing a diffusion section of an electron beam. As nuclear radiation is applied to materials, the materials are ionized or excited and emit orbital electrons forming free radicals, which change the materials into new materials by varying physical or chemical composition thereof, or cause loss or failure of organisms (microorganisms and so on), and thus facilitating irradiation sterilization. An irradiation-based method for processing products and improving performance thereof is referred to as irradiation processing. Different from conventional mechanical processing or hot processing, high energy electrons or γ rays in irradiation processing feature strong penetration capability, and can go deep into materials and conduct processing at a molecular level (which is essentially a nano processing technology). Processed objects are high energy rays and intermediates with high activity that are generated thereby. The irradiation processing features low power consumption, no residue, and small amount of pollution since it is thermal motion of molecules generating no heat effect, and thus is widely used in the fields of industry, agriculture, medical science, biology, as well as environmental protection. There are two types of radiation source for irradiation processing: radioisotopes such as cobalt source, and charged particle accelerators such as electron accelerators. Advantages of the electron accelerators are that energy thereof is controllable, electron beams are directly applied to a radiated product and thus utilization efficiency of the accelerators is high, there is no need for treating spent radiation source, they do not consume power as being shut down, and they almost bring about no pollution to the environment since only very small amount of ozone during production. Therefore, the electron accelerators tend to be used by more and more users in irradiation processing. A diameter of a spot of an electron beam bunch accelerated by the electron accelerator is normally around 1 cm, a power of electron beam current is approximately 10-50 KW (in some cases may be up to 100 KW), energy of the electron beam is concentrated in a range that is not big enough, which makes it impossible to be used for irradiation processing products since centralized energy may cause damage thereof or un-uniformity of irradiation dose. Therefore, a device for diffusing the electron beam must be used after the electron beam leaves the electron accelerator and before the electron beam reaches an object. At present, a scanning magnet is used. The magnet is powered by a saw tooth wave power source, and transversely scans the electron beam (similar to row scanning of TVs). A device under the electron beam forces a radiated object to longitudinally pass through the electron beam with a uniform speed (similar to frame scanning of TVs), so that the object is processed with uniform irradiation dose, which basically solves the above-mentioned problem. FIG. 1(a) is a schematic view of a scanning magnet with energy of 0.5 MeV and a current intensity of 50 mA, and FIG. 1(b) illustrates principle of the scanning magnet. However, there are several problems with the electron beam scanning method: it consumes electric power, and large heterogeneous products cannot be uniformly irradiated thereby. Moreover, flyback generated during scanning, and improper cooperation between a travel speed and a scanning frequency may cause un-uniformity of irradiation dose. The inventor's Chinese patent No. ZL 201010532758.1 named ‘DEVICE FOR DIFFUSING ELECTRON BEAM IN IRRADIATION PROCESSING’ theoretically raises a solution for solving the above-mentioned problems with the conventional electron beam scanning method, in which electron beams are uniformly diffused and then irradiated on a product without electric driving. Specifically, a first group of permanent magnets uniformly diffuse the electron beams, and a second group of permanent magnets reshape periphery of the electron beam. However, this solution has the following two disadvantages in application: (1) the inventor finds that an electron-beam bunch formed in the above-mentioned patent is uniformly distributed within a range of 1000 mm (length)400 mm (width). But in practice, if all electron beams use this scanning method, a longitudinal size of the electron beam after scanning will be approximately 10 mm. To broaden the electron beam and improve irradiation quality, longitudinal scanning is used, but the longitudinal size can only be increased to 30 mm, and a longitudinal size of a titanium window being used is normally within 100 mm. In contrast, a longitudinal size of a titanium window in the above-mentioned patent is greater than 400 mm, which means that if the solution in the patent is used, a device under the electron beam is to be largely modified, which hampers wide application thereof in irradiation processing and production. (2) electron-beam bunches need to be uniformly distributed so as to prevent damage of products or un-uniformity of irradiation dose caused by centralized energy. As for the electron-beam bunches in the above-mentioned patent, they are distributed by transversely defocusing a magnetic field formed by magnetic poles and longitudinally focusing the magnetic field, and only if uniformity of the magnetic field is maintained can that of the electron-beam bunch be ensured. However, the patent does not teach clearly how to maintain the uniformity of the magnetic field. In view of the above-described problems with a conventional device for diffusing an electron beam in irradiation processing, it is one objective of the invention to provide a device for optimizing a diffusion section of an electron beam that is capable of reasonably compressing a longitudinal size of an electron-beam bunch after diffusion to approximately 80 mm, which ensures optimum irradiation uniformity and efficiency, and enables the longitudinal size to be within the range of a conventional titanium window, To achieve the above objective, in accordance with one embodiment of the invention, there is provided a device for optimizing a diffusion section of an electron beam, comprising two groups of permanent magnets, a first group of permanent magnets comprising four magnetic poles fixed on an upper magnetic yoke and a lower magnetic yoke in pairs, a polarity of a magnetic pole being different from that of another magnetic pole adjacent or opposite thereto, a magnetic field formed by the four magnetic poles extending the electron beam in a longitudinal direction, and compressing the electron beam in a transverse direction, so that the electron beam becomes an approximate ellipse; a second group of permanent magnets comprising eight magnetic poles fixed on an upper magnetic yoke, a lower magnetic yoke, a left magnetic yoke, and a right magnetic yoke in pairs, a polarity of a magnetic pole being different from that of another magnetic pole adjacent or opposite thereto, a magnetic field formed by the eight magnetic poles optimizing an edge of a dispersed electron-beam bunch into an approximate rectangle; the device further comprises four longitudinal connection mechanisms, both ends of each of the upper magnetic yoke and the lower magnetic yoke of the first group of permanent magnets are respectively disposed on the left magnetic yoke and the right magnetic yoke via a longitudinal connection mechanism, both ends of each of the upper magnetic yoke and the lower magnetic yoke of the second group of permanent magnets are respectively disposed on the left magnetic yoke and the right magnetic yoke via another longitudinal connection mechanism; by controlling the four longitudinal connection mechanisms so that the upper magnetic yoke and the lower magnetic yoke of the first group of permanent magnets move synchronously towards the center thereof thereby longitudinally compressing the electron beam in the shape of an approximate ellipse, and the upper magnetic yoke and the lower magnetic yoke of the second group of permanent magnets move synchronously towards the center thereof thereby longitudinally compressing the electron beam in the shape of an approximate rectangle, and the process of longitudinal compression is repeated until a longitudinal size of the electron-beam bunch is reduced to 80 mm. In a class of this embodiment, the device further comprises a supporting block disposed between adjacent magnetic poles on one side of the magnetic yoke, and operating to prevent the magnetic poles from deviation due to attractive force thereof. In a class of this embodiment, the device further comprises four slide bars operating to correspondingly connect four corner points formed by the four magnetic yokes of the first group of permanent magnets with four corner points formed by the four magnetic yokes of the second group of permanent magnets, the first group of permanent magnets being fixed with respect to the slide bar, and the second group of permanent magnets being movable along the slide bar, thereby adjusting a distance between the first group of permanent magnets and the second group of permanent magnets; and a locking mechanism operating to fix the distance between the first group of permanent magnets and the second group of permanent magnets. In a class of this embodiment, a groove is disposed at the surface of the magnetic yoke, and interference fit with one end of the magnetic pole for receiving the magnetic pole, the groove being fixed by attractive force between the magnetic pole and the magnetic yoke, and via a fixed mount made of aluminum alloy. In a class of this embodiment, the device further comprises a pad disposed between the groove and the magnetic pole In a class of this embodiment, the longitudinal connection mechanism is facilitated by: an upper strip-form through hole and a lower strip-form through hole are disposed on the left magnetic yoke or the right magnetic yoke, and operate to respectively receive one end of each of the upper magnetic yoke and the lower magnetic yoke via screws, and calibration is labeled on the wall of the through holes, and allows determination of positions of the upper magnetic yoke and the lower magnetic yoke via a vernier caliper. The other objective of the invention is to provide a method for optimizing a diffusion section of an electron beam using a device for optimizing a diffusion section of an electron beam that is capable of reasonably compressing a longitudinal size of an electron-beam bunch after diffusion to approximately 80 mm, which ensures optimum irradiation uniformity and efficiency, and enables the longitudinal size to be within the range of a conventional titanium window In accordance with another embodiment of the invention, there is provided a method for optimizing a diffusion section of an electron beam using a device for optimizing a diffusion section of an electron beam, the device comprising two groups of permanent magnets, a first group of permanent magnets comprising four magnetic poles fixed on an upper magnetic yoke and a lower magnetic yoke in pairs, a polarity of a magnetic pole being different from that of another magnetic pole adjacent or opposite thereto, a magnetic field formed by the four magnetic poles extending the electron beam in a longitudinal direction, and compressing the electron beam in a transverse direction, so that the electron beam becomes an approximate ellipse; a second group of permanent magnets comprising eight magnetic poles fixed on an upper magnetic yoke, a lower magnetic yoke, a left magnetic yoke, and a right magnetic yoke in pairs, a polarity of a magnetic pole being different from that of another magnetic pole adjacent or opposite thereto, a magnetic field formed by the eight magnetic poles optimizing an edge of a dispersed electron-beam bunch into an approximate rectangle, wherein the method comprises: forcing the upper magnetic yoke and the lower magnetic yoke of the first group of permanent magnets to move synchronously towards the center thereof thereby longitudinally compressing the electron beam in the shape of an approximate ellipse, and the upper magnetic yoke and the lower magnetic yoke of the second group of permanent magnets to move synchronously towards the center thereof thereby longitudinally compressing the electron beam in the shape of an approximate rectangle, and repeating the process of longitudinal compression until a longitudinal size of the electron-beam bunch is reduced to 80 mm. Advantages of the invention comprise: The invention employs two groups of permanent magnets to uniformly diffuse, reshape and longitudinally compress the electron beam, so that the longitudinal size thereof is close to 80 mm, which on the one hand ensures uniformity and optimum efficiency of irradiation, and on the other hand, enables the longitudinal size to be within the range of a conventional titanium window, thereby making it possible to update and upgrade a processing equipment of the electron beam by replacing general-purpose electron beam scanning devices without changing structure of the device under the electron beam. In addition, the device consumes no electric power, and features simple structure, low cost, convenient installation, and good practicability. The device of the invention can replace the electron beam scanning device that is widely used nowadays, in that it does not need a scanning power supply, which saves electric power, and overcomes a problem of additional cost and low operation efficiency caused by failure thereof, reduces possibility of a titanium film's damage, eliminates flyback of the electron beam, and ensures quality of products during electron beam production. For clear understanding of the objectives, features and advantages of the invention, detailed description of the invention will be given below in conjunction with accompanying drawings and specific embodiments. It should be noted that the embodiments are only meant to explain the invention, and not to limit the scope of the invention. The invention aims to improve a conventional device for diffusing an electron beam in irradiation processing. The conventional device for diffusing an electron beam in irradiation processing comprises two groups of permanent magnets, the first group of permanent magnets I comprises four magnetic poles 15, 16, 17 and 18 fixed on an upper magnetic yoke 12 and a lower magnetic yoke 14 in pairs, a polarity of a magnetic pole being different from that of another magnetic pole adjacent or opposite thereto. The first group of permanent magnets extend the electron beam in a longitudinal direction, and compress the electron beam in a transverse direction, so that the electron beam becomes an approximate ellipse. The second group of permanent magnets II comprises eight magnetic poles 25-32 fixed on an upper magnetic yoke, a lower magnetic yoke, a left magnetic yoke, and a right magnetic yoke in pairs, a polarity of a magnetic pole being different from that of another magnetic pole adjacent or opposite thereto. A magnetic field formed by the eight magnetic poles optimizes an edge of a dispersed electron-beam bunch into an approximate rectangle. As described in the description of the related art, a longitudinal width of an electron-beam bunch obtained by the conventional device for diffusing an electron beam is greater than 400 mm, which exceeds a longitudinal size of a conventional titanium window (within 100 mm) Therefore, it is required to compress the longitudinal size of the electron-beam bunch. On the other hand, since the scanning magnet is limited by a scanning power supply, the longitudinal size can only be up to 35 mm, and a larger size may significantly affect scanning uniformity. Hence, a final irradiation width should be as large as possible in practice. The invention facilitates maximization of the titanium window's area, and optimum irradiation uniformity and efficiency without modifying an original electron accelerator by compressing the longitudinal size of the electron-beam bunch to 80 mm, taking a size of a scanning box and structure of a titanium film into account. To compress the longitudinal size of the electron-beam bunch, the invention uniformly diffuses the electron beam via the first group of permanent magnets, and longitudinally compresses the electron beam bunch for the first time; and reshapes periphery of the diffused electron beam via the second group of permanent magnets, and longitudinally compresses the electron beam bunch to 80 mm for the second time, as shown in FIGS. 2 and 3, in details: both ends of each of the upper magnetic yoke 12 and the lower magnetic yoke 14 of the first group of permanent magnets I are respectively disposed on the left magnetic yoke 11 and the right magnetic yoke 13 via a longitudinal connection mechanism, the left magnetic yoke 11, the upper magnetic yoke 12, the right magnetic yoke 13 and the lower magnetic yoke 14 form a rectangle. Firstly the first group of permanent magnets is used for uniformly diffusing the electron beam, and then the longitudinal connection mechanism is controlled to force the upper magnetic yoke and the lower magnetic yoke to approach the center of the rectangle at the same step thereby reducing a distance between the upper magnetic pole and the lower magnetic pole, as well as the magnitude of the magnetic field, and thus longitudinally compressing the electron-beam bunch for the first time. Both ends of each of the upper magnetic yoke 22 and the lower magnetic yoke 24 of the second group of permanent magnets II are respectively disposed on the left magnetic yoke 21 and the right magnetic yoke 23 via another longitudinal connection mechanism. The left magnetic yoke 21, the upper magnetic yoke 22, the right magnetic yoke 23 and the lower magnetic yoke 24 form a rectangle. Firstly a magnetic field formed by the second group of permanent magnets is used for reshaping periphery of the ellipse thereby forming an approximate rectangle. Then the longitudinal connection mechanism is controlled to force the upper magnetic yoke and the lower magnetic yoke to approach the center of the rectangle at the same step thereby reducing a distance between the upper magnetic pole and the lower magnetic pole, and thus longitudinally compressing the electron-beam bunch for the second time. The first group of permanent magnets and the second group of permanent magnets cooperate with each other, and repeat the process of longitudinal compression until a longitudinal size of the electron-beam bunch is close to 80 mm. The invention uses the first group of permanent magnets as a main part, and the second group of permanent magnets as an auxiliary part, and facilitates longitudinal compression by cooperation therebetween. The principle of this is, as the electron-beam bunch is longitudinally compressed upon passing through the first group of permanent magnets, similar to convex lens, as the electron-beam bunch is diffused to the second group of permanent magnets, a movement direction and a movement speed thereof make it impossible to affect the bunch by the second group of permanent magnets. It should be noted that as the upper magnetic yoke and the lower magnetic yoke approach the center of the rectangle, they should move at the same step, so as to ensure the electron-beam bunch is always located at the center of the compressing device, and is uniformly diffused. Installation and adjustment of the magnetic pole of the invention are shown in FIG. 4. Since machining magnetizing errors (comprising errors caused by processing technology and installation of the magnetic yoke) exist, an end of each of the magnetic poles on the same side in the vicinity of the center is not on the same horizontal plane, causing a magnetic field generated by the permanent magnet is not uniformly distributed at the center thereof, the electron-beam bunch is not uniformly diffused, and finally a diffusion section thereof cannot meet design requirement. A groove is disposed at the surface of the magnetic yoke, and interference fit with one end of the magnetic pole for receiving the magnetic pole, the groove being fixed by attractive force between the magnetic pole and the magnetic yoke, and via a fixed mount 35 made of aluminum alloy. The fixed mount 35 is fixed on the magnetic yoke via a screw 37. A supporting block made of steel is disposed between adjacent magnetic poles on one side of the magnetic yoke, and operates to prevent the magnetic poles from deviation due to attractive force thereof. Since magnetic force between magnets is very large, the supporting block 36 is also disposed at the center of the fixed mount made of aluminum alloy outside the magnetic pole, and operates to prevent the magnetic pole from deviation due to attractive force thereof. To adjust a position of the magnet in a direction vertical to the magnetic yoke, multiple pads 38 with different thickness (such as 1 mm, 2 mm, 5 mm and so on) are disposed in the groove, and materials forming the pad are the same as those of the magnetic yoke. Since attractive force between the magnet and the magnetic yoke is very large, a through hole is disposed at the bottom of the groove for making it easy to take the magnetic out. FIG. 5 illustrates the longitudinal connection mechanisms of the two groups of permanent magnets: the upper magnetic yoke and the lower magnetic yoke operate as adjusting magnetic yokes, and the left magnetic yoke and the right magnetic yoke operate as fixed magnetic yoke. A strip-form through hole is disposed on the fixed magnetic yoke, and operates to receive the magnetic yoke by adjusting both sides thereof. A position of one magnetic yoke with respect to the other magnetic yoke can be fixed by using screws. In adjustment, the screws are released, and the magnetic yokes move to a predetermined position, a position of one magnetic yoke with respect to the other is determined by a vernier caliper. Precision of this kind of adjustment can be 0.1 mm, and an adjustment range is 30 mm. As shown in FIG. 6, four slide bars 39 correspondingly connect four corner points of the first group of permanent magnets with four corner points of the second group of permanent magnets. Specifically, a base 41 is fixed on the second group of permanent magnets, and connected to the first group of permanent magnets via the slide bar 39. A bearing 40 operates to fix a position of the first group of permanent magnets after movement. In use, the second group of permanent magnets is fixed, and the first group of permanent magnets moves in parallel therewith via four slide bars 39, the four slide bars 39 are fixed on the second group of permanent magnets via four bases 41, four bearings 40 are disposed on four corners of the second group of permanent magnets, and fit on the slide bars, and can slide up and down thereon. Two threaded rods 42 are disposed on both sides of the second group of permanent magnets, and operate to connect the first group of permanent magnets to the second group of permanent magnets. The threaded rod is fixed via a locking mechanism 43, so as to fix said distance between the first group of permanent magnets and the second group of permanent magnets. Precision of this kind of adjustment can be up to 0.1 mm, and an adjustment range is 50 mm, which enable the invention to feature good adjustment precision, and thus facilitating uniform diffusion of the electron-beam bunch. FIG. 7 illustrates installation of the device of the invention on an irradiation accelerator. The invention can be directly disposed at a scanning chamber of the accelerator for replacing a scanning magnet. A group of supporting frames 44 is disposed below a longitudinal compression device for positioning. The bottom of the supporting frame is fixedly connected to a screw of a scanning box 45, and an upper surface thereof is fixedly connected to a magnet so that the center of the magnet coincides with the screw of the scanning box, thereby facilitating good adjustment precision and stability. Next advantages of the invention will be described using an example of applying the invention to 0.3 MeV and 0.5 MeV irradiation accelerators. A diameter of a spot of an electron beam bunch from the 0.5 MeV accelerator is 15 mm, and transverse scanning and longitudinal scanning are conducted on the electron beam after it passes through a traditional magnet, and a size of the electron-beam bunch after scanning at the titanium film is: 650 mm (length)35 mm (width).After the electron beam passes through the device for diffusing the electron beam with a longitudinal section-compression function, a size of a diffused electron beam at the titanium window can reach 780 mm (length)80 mm (width), which indicates the invention can greatly increase a width and a length of irradiation over a conventional scanning method. FIGS. 8 and 9 respectively illustrates distribution of electrons on an irradiated object after the electrons are diffused by the permanent magnet as the invention is applied to 0.5 MeV and 0.3 MeV accelerators. It can be seen that if the device of the invention is fine adjusted, the invention can be applicable for accelerators with different energy, and diffuse a size of the electron-beam bunch to be within 800 mm (length)80 mm (width). While particular embodiments of the invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects, and therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit and scope of the invention.
051125676	claims	1. In a nuclear reactor system having a pressure vessel and a guide conduit for a measurement probe of elongate and generally cylindrical shape extending into said reactor vessel, a device for shutting off said conduit, said device comprising (a) a housing inserted between a lower section of the conduit in communication with the pressure vessel and an upper section of the conduit and having two means for leakproof connection to the lower section and the upper section of the conduit, respectively, and a wall bounding an inner chamber of said housing; (b) a passage channel for the measurement probe comprising an upper part passing through the means of connection of the housing to the upper section of the conduit and a lower part passing through the means of connection of the housing to the lower section of the conduit, emerging in an inner chamber of the housing; (c) a shutter arranged in said inner chamber and oscillating about a horizontal axis between a closed and an open position of an inner end of the upper part of the passage channel emerging in the inner chamber and comprising a closing member which cooperates with said inner end in a closed position to close the passage channel and a counterweight for returning the closing member in the closed position; and (d) means for measuring the pressure into the inner chamber of the housing. 2. Shutoff device according to claim 1, wherein said wall of said housing comprises a body and a cover attached in a leakproof manner by virtue of a seal onto said body and clamped by a plurality of bolts. 3. Shutoff device according to claim 1, wherein said upper connection means of the housing consists of a nozzle comprising a bore with a vertical axis emerging into said inner chamber of said housing, in which bore there is fastened a seat comprising a support bearing for said closing member of said shutter. 4. Shutoff device according to claim 3, wherein said seat is fastened in said bore of said nozzle by a bolt engaged and fastened in a leakproof manner in aid bore of said nozzle and bearing on said seat, said seat and said bolt being pierced axially to form the passage channel for said measurement probe. 5. Shutoff device according to claim 3, wherein said seat is made of graphite. 6. Shutoff device according to claim 1, wherein said shutter comprises a balance arm fixed to a shaft rotatably mounted inside said housing, said shaft having a first end part to which said closing member is fastened and a second end part remote from said first end part relative to the axis of rotation of said shutter and carrying said counterweight. 7. Shutoff device according to claim 6, wherein said shaft comprises conically shaped end pivots engaged in bearings of corresponding shape, said bearings being placed in cavities arranged in the inner surface of said wall of said housing. 8. Shutoff device according to claim 7, wherein resilient return elements are inserted between said bearings and corresponding parts of said cavities in said wall of said housing. 9. Shutoff device according to claim 7, wherein said cavities receiving said bearings are machined into two components which are attached to each other to form said housing. 10. Shutoff device according to claim 1, wherein said guide conduit closed at one of its ends through which it is introduced into said pressure vessel comprises an end part remote from its closed end, said end part being open and emerging outside a vertical guide tube, by means of a leakproof passage device situated at a height above the upper level of the reactor vessel, and said housing is inserted in a vertical end part of said guide conduit above said leakproof passage device. 11. Shutoff device according to claim 10, wherein said device for measuring pressure is connected to an alarm means situated in a measuring room receiving the upper part of said guide conduit. 12. Shutoff device according to claim 11, wherein the upper end part of said guide conduit is connected to a leakproof manual closing valve.
	claims	1. A submersible machine structured to carry a tool to a limited access location within a nuclear containment, to become mounted to and to be driven along a structural portion of a reactor apparatus within the nuclear containment, and to insert at least a portion of the tool into the limited access location, the submersible machine comprising:a transport portion comprising a frame, at least a first flotation device disposed on the frame, and a number of thrusters mounted to the frame and structured to be actuated to move the frame through a fluid environment within the nuclear containment;an adjustment table comprising a first platform apparatus having a first translation mechanism and a second platform apparatus having a second translation mechanism, the first and second platform apparatuses being connected together, the first platform apparatus being connected with the frame, at least one of the first platform apparatus and the second platform apparatus being movable in a plane with respect to the other of the first platform apparatus and the second platform apparatus;a mount apparatus connected with the second platform apparatus and comprising a drive apparatus and a number of brace elements, the drive apparatus comprising a motor and a wheel, the wheel and at least a first brace element of the number of brace elements being cooperable to engage therebetween the structural portion of the reactor apparatus within the nuclear containment and to thereby mount the mount apparatus to the reactor apparatus, the motor being actuatable to transfer motile force to the wheel to drive the submersible machine along the reactor apparatus;the second translation mechanism being operable independently of the motor to move the first platform apparatus along a direction in the plane with respect to the mount apparatus when the mount apparatus is mounted to the structural portion of the reactor apparatus, the direction being one of a radial direction and a tangential direction with respect to the reactor apparatus;the first translation mechanism being operable independently of the second translation mechanism to move the frame with respect to the second platform apparatus along another direction in the plane that is transverse to the direction and that is the other of a radial direction and a tangential direction with respect to the reactor apparatus; anda mast apparatus mounted to the frame and comprising a mast that is structured to carry the tool, the mast apparatus being operable independently of the first translation mechanism to move the mast with respect to the frame. 2. The submersible machine of claim 1 wherein the mast is an elongated telescoping member. 3. The submersible machine of claim 2 wherein the mast is additionally pivotable with respect to the frame. 4. The submersible machine of claim 3 wherein the mast is additionally rotatable about its axis of elongation. 5. The submersible machine of claim 1 wherein the mount apparatus further comprises an engagement apparatus structured to move the wheel independently of operation of the motor into engagement with the structural portion of the reactor apparatus. 6. The submersible machine of claim 1 wherein the first platform apparatus and the second platform apparatus are movable independently of one another in directions orthogonal to one another. 7. The submersible machine of claim 5 wherein the number of brace elements comprise a pair of rollers, the wheel being structured to compressively engage the structural portion of the reactor apparatus between the wheel and the pair of rollers. 8. A submersible machine structured to carry a tool to a limited access location within a nuclear containment, to become mounted to and to be driven along a structural portion of a reactor apparatus within the nuclear containment, and to insert at least a portion of the tool into the limited access location, the submersible machine comprising:a transport portion comprising a frame, at least a first flotation device disposed on the frame, and a number of thrusters mounted to the frame and structured to be actuated to move the frame through a fluid environment within the nuclear containment;an adjustment table comprising a first platform apparatus having a first translation mechanism and a second platform apparatus having a second translation mechanism, the first and second platform apparatuses being connected together, the first platform apparatus being connected with the frame, at least one of the first platform apparatus and the second platform apparatus being movable in a plane with respect to the other of the first platform apparatus and the second platform apparatus;a mount apparatus connected with the second platform apparatus and comprising a drive apparatus and a number of brace elements, the drive apparatus comprising a motor and a wheel, the wheel and at least a first brace element of the number of brace elements being cooperable to engage therebetween the structural portion of the reactor apparatus within the nuclear containment and to thereby mount the mount apparatus to the reactor apparatus, the motor being actuatable to transfer motile force to the wheel to drive the submersible machine along the reactor apparatus;the second translation mechanism being operable independently of the motor to move the first platform apparatus along a direction in the plane with respect to the mount apparatus when the mount apparatus is mounted to the structural portion of the reactor apparatus;the first translation mechanism being operable independently of the second translation mechanism to move the frame with respect to the second platform apparatus along another direction in the plane that is transverse to the direction;a mast apparatus mounted to the frame and comprising a mast that is structured to carry the tool, the mast apparatus being operable independently of the first translation mechanism to move the mast with respect to the frame; andwherein the mast is an elongated member that telescopes along its axis of elongation, that is rotatable about its axis of elongation, and that is pivotable with respect to the frame independently of the first translation mechanism.
054689708	description	DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 2 diagrammatically shows a section of a collimation device conforming to the invention and able to collimate an incident beam of radiation 4 and obtain at the outlet of this collimation device a collimated beam 6, the maximum divergence of this outgoing beam 6 being equal to 2.phi.. The collimation device or collimator shown in FIG. 2 includes a plurality of parallel plys 8 of wires 10 which are made of or coated with a material able to absorb the radiation. In the example shown in FIG. 2, the plys 8 are equidistant from one another and in each ply 8 the wires 10 are round wires parallel to one another and the wires of a given row, that is with the same order number in the plys, are in planes P parallel to one another and perpendicular to the planes of the plys 8. FIG. 3 shows a perspective view of a collimator conforming to the invention. As can be seen in FIG. 3, the wires 10 are individually stretched between two parallel plates 12 which are rendered strictly integral with each another, for example by means of braces 14 (placed outside the beam to be collimated 4). In order to collimate a beam of neutrons, boron wires which are able to be stretched between the plates 12 are preferably used. As a variant, it is possible to use tungsten wires coated with boron. In the case where one wishes to collimate a beam of X rays, use is made of wires which are made of or coated with a material able to absorb the X rays, preferably tungsten wires. FIG. 4 diagrammatically shows the way on how the wires are placed in relation to one another in a collimator conforming to the invention so as to use a minimum number of wires. The collimator diagrammatically and partly shown in FIG. 4 includes a plurality of parallel plys of round wires, such as the adjacent plys A and B. Having selected the maximum divergence 2.phi. it is desired to obtain with the collimator of FIG. 4, the distance D12 is selected between the first two wires A1 and A2 of the ply A (which is equal to the distance between the first two wires B1 and B2 of ply B). Then the position of the third wire A3 of the ply A is determined and the position of the third wire B3 of the ply B is determined as indicated hereafter. The wire A3 is tangent to the plane B1 A2 which passes between the wires B1 and A2 and which is tangent to these wires B1 and A2. Similarly, the wire B3 is tangent to the plane A1 B2 which passes between the wires A1 and B2 and which is tangent to these wires A1 and B2. Then the position of the wires A4 and B4 is determined as follows. The wire A4 is tangent to the plane B1 A3 which passes between the wires B1 and A3 and which is tangent to these wires B1 and A3. Similarly, the wire B4 is tangent to the plane A1 B3 which passes between the wires A1 and B3 and which is tangent to these wires A1 and B3. Thus, FIG. 4 shows how the collimator is gradually formed. The construction of this collimator is completed with the wires of row n, such as the wires An and Bn, making it possible to obtain the initially fixed maximum angle of divergence 2.phi.. The distance Li between the wires Ai and Ai+1 (equal to the distance between the wires Bi and Bi+1) depends on the distance d of the wires and the local angular divergence 2.times..phi.i of the beam of radiation at the level of the wires of row i (FIG. 4 shows the parameters L4 and 2.times..phi.4 which relate to the wires of row i=4). The distance Li (maximum distance between the wires Ai and Ai+1) is such that: EQU Li=d/tg.phi.i. As .phi.i reduces when i increases, that is gradually when the radiation extends into the collimator (in other words when going away from the inlet E of this collimator), the spacing Li of the wires is an increasing function of i. The construction explained above thus makes it possible to embody a collimator conforming to the invention with a minimum number of wires. By way of non-restrictive illustration, in order to embody a collimator conforming to the invention for collimating a beam of neutrons and obtain at the outlet of this collimator a maximum angular divergence beam equal to 0.5.degree., the following parameters are used: boron wire, diameter 0.1 mm PA1 length of collimator: 250 mm PA1 distance between two adjacent plys: 2.2 mm. The present invention is able to significantly reduce and, in certain preferred embodiments, completely eliminate the total reflection of the radiation. Furthermore, the fact of stretching the wires individually makes it possible to clearly define the ply constituted by these wires, contrary to the case with stretched strips which are used in known types of Soller collimators, these strips from a mechanical point of view having a poorly determined position, especially at the inlet and outlet of this Soller collimator (it never being possible to ensure that a strip is not warped). In addition, the wires are less sensitive than these strips to thermic variations and degradation by the radiation.
	description	Throughout the following detailed description, similar reference characters refer to similar elements in all figures of the drawings. Tiling, in the present context, means the assembly of a plurality of prototiles by arraying the prototiles contiguously side by side to form a large area comprising a plurality of prototiles. As explained in xe2x80x9cA series of books in the mathematical sciencesxe2x80x9d edited by Victor Klee, Copyright 1987, page 20, basic notions, paragraph 1.2 xe2x80x9cTilings with tiles of a few shapesxe2x80x9d, monohedral tiling is the process of assembling a plurality of same size and shape tiles. Each of these tiles is called a prototile. In the present description, when we refer to tiling we imply monohedral tiling, and when we refer to xe2x80x9cprototilexe2x80x9d, consistent with accepted terminology, we refer to an individual tile of a group of same size and shape tiles. Such prototiles may be virtual, that is exist only as a mathematical expression or may take physical form such as a displayed soft or hard image. When the prototiles contain a design within the prototile, referred to herein as a xe2x80x9cmotifxe2x80x9d the combined motifs of all the tiled prototiles forms a pattern. Referring now to FIG. 1, there is shown a radiation detection panel 10 useful for radiographic imaging applications. The panel 10 comprises a plurality of sensors 12 arrayed in a regular pattern. Each sensor comprises a switching transistor 14 and a radiation detection electrode 16 which defines the sensor radiation detection area. Each radiation detection area has a width xe2x80x9cWSxe2x80x9d and a length xe2x80x9cLSxe2x80x9d, and is separated from an adjacent radiation detection area by an interstitial space xe2x80x9cSxe2x80x9d. The interstitial spaces are substantially incapable of detecting incident radiation. Associated with the sensors there is also a sensor pitch along the sensor length, xe2x80x9cPLxe2x80x9d and a sensor pitch along the sensor width, xe2x80x9cPWxe2x80x9d. FIG. 2 shows a schematic section elevation of a portion of the panel 10 viewed along arrows 2xe2x80x942 in FIG. 1. The sensor used for illustrating this invention is of the type described in U.S. Pat. No. 5,319,206 issued to Lee et al. and assigned to the assignee of this application, and in pending application Ser. No. 08/987,485, Lee et al., filed Dec. 9, 1997, also assigned to the assignee of this application. Briefly a sensor of this type comprises a dielectric supporting base 20. On this base 20 there is constructed a switching transistor 22, usually an FET built using thin film technology. The FET includes a semiconductor material 25, a gate 24, a source 26 and a drain 28. Adjacent the FET there is built a first electrode 30. A dielectric layer 32 is placed over the FET and the first electrode 30. A collector electrode 34 is next placed over the first electrode 30 and the FET 22. Over the collector electrode there is placed an barrier or insulating layer 36 and over the insulating layer 36 a radiation detection layer 38 which is preferably a layer of amorphous Selenium. A second dielectric layer 40 is deposited over the radiation detection layer, and a top electrode 42 is deposited over the top dielectric layer. The barrier or insulating layer 36, the radiation detection layer 38, the second dielectric layer 40 and the top electrode layers are continuous layers extending over all the FETs and collector electrodes. In operation, a static field is applied to the sensors by the application of a DC voltage between the top electrode and the first electrodes. Upon exposure to X-ray radiation, electrons and holes are created in the radiation detection layer which travel under the influence of the static field toward the top electrode and the collector electrodes. Each collector electrode collects charges from area directly above it, as well as some fringe charges outside the direct electrode area. There is thus an effective radiation sensitive area xe2x80x9cWxe2x80x9d associated with this type of sensor which is somewhat larger that the physical area of the collector electrode. The sensitive areas are separated by a dead space D. In the case where the effective sensitive area is equal to the electrode area, D becomes the interstitial S space. In an embodiment where the radiation detection layer is columnized, that is where the radiation detection layer extends upward from the collector electrode in an isolated column, the radiation sensitive area will be the same as the physical area of the collector electrode. This is particularly true in the type of sensor which employs a photodiode together with a radiation conversion phosphor layer. In such cases the phosphor layer is usually structured as discreet columns rising above the photodiode. In describing this invention we will use the term xe2x80x9cradiation sensitive areaxe2x80x9d to designate the actual area which is radiation sensitive, whether it is the same as the physical area of the sensor or not. We will use the term xe2x80x9copaquexe2x80x9d to designate radiation absorption material. In addition, because in practical use an anti-scatter grid is (a) three dimensional and (b) is occasionally placed spaced from the surface of the radiation detection layer, the terms prototile width and prototile length refer to the width and length of a prototile such that its projected image on the sensitive surface satisfies the required relationships between prototile dimensions and sensitive surface dimensions, when the prototile is in the grid plane. For design purposes, this can be any plane through the grid, parallel to the width and length of the grid. Preferably, this plane is the plane closest to the sensitive surface. Finally, while the grid is usually described as having a height perpendicular to its width and length, it is to be understood that this height can also be inclined with respect to the perpendicular to produce a grid having opaque elements aligned with the incident radiation path which may be a path that diverges radially from the radiation source. This type of grid element orientation is also well known in the art and grids having such inclined wall are described in the aforementioned U.S. Pat. No. 4,951,305 Moore et al. (See particularly Moore, FIG. 8.) Grids having such oriented elements are still to considered as being included when there is reference to a grid height. In practice, particularly where the grid is placed in contact with, or close to the sensitive surface, the projected and actual dimensions will be substantially the same, in which case the actual dimensions will be convenient to use. FIG. 3 shows a radiation detection panel of the type described above with a scattered radiation shielding grid 44 placed over the panel. As shown in the figure, the grid comprises a pattern of a plurality of opaque strips 46 and 48 aligned along the width and length of the panel. This type of anti-scatter grid, is a common type of anti-scatter grid available, and may be manufactured easily. See for instance U.S. Pat. No. 5,606,589 issued to Pellegrino et al. which discloses such a cross grid and a method for its manufacture and use in medical radiography. However, use of this type of grid with a radiation detection panel of the type disclosed above is prone to the production of Moirxc3xa9 patterns, unless, as taught by Tsukamoto et al., U.S. Pat. No. 5,666,395 the grid is fixed in relationship to the underlying array of radiation sensors, the grid pitch is the same as the array pitch, and the grid bars are aligned with the centerlines of the interstitial spaces. The present invention employs a grid having a pattern of absorbing material that does not produce Moirxc3xa9 patterns without requiring the exact placement of the grids of the prior art. As clearly shown in FIG. 3, the absorbing material pattern of grid 44 is not aligned with the interstitial or dead spaces of the underlying array of sensitive areas 11. Unlike the Tsukamoto grid, grid 44 may be placed anywhere and still function effectively. Further more the grid may be moved during the radiation exposure. Grid 44 has been designed in accordance with this invention by tiling a plurality of prototiles 50 shown in dotted lines in FIG. 3 to generate the pattern for the absorbing material. As better shown in FIG. 3A, the prototile 50 has a width Wp and a length Lp. The width of the prototile Wp equals the width Ws of the radiation sensitive area 11 of the sensor of the panel divided by an integer A. Thus Wp=Ws/A. In most instances A=1. The same is applicable to the length Lp of the prototile relative to the length Ls of the sensitive area; again Lp=Ls/B, where B is an integer, and again, preferably B=1. Each of the prototiles includes a motif 52 which will be used to design the opaque portion of the grid. In FIG. 3A this motif is a cross. The motif is selected such that when the prototiles are tiled, the motifs of the plurality of the tiled prototiles combined form the pattern shown in FIG. 3. This is the pattern for the opaque material in the grid. The grid pattern need not be a plurality of strips intersecting at 90xc2x0 angles. A number of different grid designs can be produced using the technology disclosed in U.S. Pat. No. 5,259,016 issued to Dickerson et al. The use photographic techniques to produce radiation absorption grids having shapes other than straight lines is shown in that reference and can be used to produce grids designed using the present invention wherein the opaque grid strips are other than straight lines. The aforementioned U.S. Pat. No. 4,951,305 issued to Moore et al. also teaches methods for producing complex grid shapes. FIG. 4 shows a grid 44 generated from a prototile 50 having a width Wp and a length Lp and motif 54 shown as a single bar. The radiation sensitive area 11 has a width Ws, a length Ls. The interstitial space S separates the sensitive areas. The resultant anti-scatter grid 44 is in many respects like the common linear anti-scatter grid in common use today, except the distance between the opaque regions is equal to the sensitive area width of the sensor. For a sensitive area having a width of 135 microns the grid 44 would preferably have 188.1 bars per inch (7.407 per mm). Although the above discussion has been limited to the grid design in the x-y plane, it is understood that the grid has a third dimension along the z axis, or in other words the grid walls have a height. The wall height ranges from about 2 to 16 times the thickness of the wall. A preferred height ratio is about 6 to 12. The ratio of wall thickness to the prototype width ranges from about {fraction (1/10)} to xc2xd with a preferred ratio of about ⅙. Because the radiation impinges on the panel at different angles rather than perpendicular, i.e. along the z axis, the projection of the grid on the panel will be both magnified and distorted depending on the distance of the grid from the radiation sensitive surface, and to some extent depending on the distance and nature of the radiation source. A collimated radiation source, for instance, will produce no magnification or distortion effect, while a point source will produce both. These effects are well understood in the art and proper compensation to the grid design will be made, by designing a grid such that the projected prototile on the panel will satisfy the above developed criteria. These effects are minimized by placing the grid in close proximity and preferably intimate contact with the sensitive area, and by minimizing the grid wall height. In the example given above, if the grid 44 is spaced 1 cm away from the sensitive area of the detection panel and the X-ray generator is 1 meter away, the preferred grid 44 would have 190.0 pairs per inch (7.480 per mm) to correct for the geometric magnification, instead of 188.1 bars per inch (7.407 per mm). Inspection of FIG. 4 shows that exactly one bar 54 of opaque material is projected onto each radiation sensitive area 11. This is obvious for most translations of the bar. It is also true when two bars partially project onto the sensitive area 11, the part of one bar not projecting onto the sensitive area is exactly equal to that projected by the other bar. Because the amount of X-rays passing to any sensitive area is constant no Moirxc3xa9 pattern interference will be introduced, either static or in translation along any line. This anti-scatter grid can be oriented horizontally in which case the tiling pitch will be made equal to the effective sensitive area length rather than the effective sensitive area width. It is a remarkable feature of the present invention that the radiation sensitive areas 11 of the radiation detection panel need not be in a regular array. As shown in FIG. 5, they may be unevenly arrayed and still enjoy the benefits of this invention. However, the radiation sensitive areas must be identical in shape, size and orientation. FIG. 5 and its associated prototile shown in FIG. 5A also illustrate a grid design and prototile motif 56 for the case where the radiation sensitive area width is different from the sensitive area length. As shown the resulting prototile width and length are also different. While there is great latitude in selecting the motif for the opaque regions in a prototile, a preferred X-ray transparent region will have no edges collinear with either edge of the sensitive area as shown in the grid of FIG. 5. Preferred X-ray opaque motifs may include circles, ovals, rectangles, and other shapes. The intention is to minimize the amount of the opaque motif of the prototile projected on the sensitive area boundary as the motif shifts its relative position with respect to the sensitive area along the panel surface. Because the resulting opaque pattern following tiling has a pitch that is less than the sensor pitch, invariably the opaque pattern will fall on the line that divides the sensitive area from the interstitial area (See FIG. 4). Again, because of the grid pitch, as the opaque area exits at one end of the sensitive area, another opaque area enters from the opposite end. If the thickness of the opaque areas were reproduced with absolute accuracy so that it is always the same, the opaque area covering the sensitive area would always be constant. However, because in practice it is difficult to create opaque areas with absolutely the same thickness, it is preferred to select a motif which creates a pattern without opaque areas parallel to the boundary between the interstitial spaces and the sensitive area. FIGS. 6A and 7A show alternate motifs M resulting in grid 44 structures shown in FIGS. 6 and 7 which do not include opaque areas parallel to the aforementioned boundary. FIGS. 8, 9, and 10 all show different grids 44 designed according to the present invention. The prototiles 50 and motifs M used in these cases are shown in FIGS. 8A, 9A, and 10A respectively. In all cases the prototile 50 has a width Wp and a length Lp as defined hereinabove. In all instances, the resulting grid of radiation absorbing pattern is such that the radiation opaque area of the grid always covers the same amount of radiation sensitive area in each sensor, regardless of the position of the grid. In summary, a grid will be constructed as follows. First, the effective radiation detection area of the panel sensors is determined to identify the radiation sensitive area and the prototile size is then determined according to the relationships given above. Next, a desired motif is created in the prototile. The prototile is then duplicated and a plurality of prototiles assembled to create the pattern of the grid which results from the combined motifs of the prototiles. Mirror images of the prototile may be used with the original prototile to create a pattern. This pattern is then used for the radiation absorption material which forms the anti-scatter grid. This material may be lead. The grid may be constructed according to the teachings of the aforementioned U.S. patents to Dickerson et al., Pellegrino et al. or Moore et al. If the grid is not to be in contact with the sensors and the radiation source is a point source, the prototile design takes into account the projection of the grid onto the sensitive area. As may be surmised by the above discussion, it is very difficult to obtain grids with the exact requisite absorbing material spacing and thickness completely free from manufacturing imperfections. Further more, thermal expansion may alter somewhat the grid element spacing, and a shift during installation may change the originally calculated distance between the grid elements and the detection panel so that the relationship W(p)=W/I no longer holds absolutely true. Surprisingly, it has been observed that some deviation of the theoretically optimum grid pattern for a particular detection panel and grid positioning is acceptable when the detection panel includes, as is almost always the case, an associated gain control circuit. Gain control circuits are used to compensate for different output levels of different individual sensors in an array of such sensors by correcting the individual output of each sensor such that when a detection panel is illuminated by uniform intensity radiation, the output of each sensor becomes the same. In a typical digital gain correction system, this involves a calibration step whereby prior to using a detection panel in an image detection system, the panel is exposed to uniform radiation at a predetermined level of intensity. Each of the individual sensors output is recorded and for each individual sensor there is generated and stored a correction factor usually in a Look-Up-Table (LUT). When an image is obtained the raw output of each sensor is corrected by the corresponding correction factor from the LUT. According to this invention, if the calibration step is undertaken with the grid in place, whereby instead of a substantially uniform illumination level the grid image is projected on the panel, variations in the grid absorbing material pattern of as much as + or xe2x88x925% from the calculated dimensions are compensated for by the gain correction system. Thus a manufactured grid whose pattern corresponds to a prototile width W(p)=W/(Ixc2x10.05I) and W(p) different (xe2x89xa0) from W+D still results in a grid that presents no objectionable Moirxc3xa9 patterns. FIG. 11 illustrates the use of this grid in a system to obtain a radiogram. The system includes a radiation source 60 which is typically an X-ray source emitting a beam of radiation 62. A target or patient 64 is placed in the beam path. On the other side of the patient there is placed a combination of a grid 66 and detection panel 68. The grid is a grid created in accordance with the present invention and has a pattern of absorbing material, such as, for instance, shown in FIG. 3 discussed earlier. Behind the grid 66 at a fixed distance therefrom is positioned a radiation detection panel 68 such as the panel described earlier in conjunction with FIGS. 1 and 2. The panel is connected over wire 70 to a control console 72 which may include a display screen 74 and/or a hard copy output device (not shown) for producing a hard copy of the radiogram. Typically the control console will also include a plurality of image processing circuits, all of which are well known in the art. Preferably, a gain control circuit is included, either as a part of the detection panel itself or as part of the control console. Preferably, the grid was originally designed such that W(p)=W/I. However even if due to manufacturing imperfections, thermal change, actual spacing between the installed grid and detection panel or whatever other reason such relationship is not satisfied exactly, as long as the actual grid pattern satisfies the relationship W(p)=W/(Ixc2x10.05I) discussed above, such grid is acceptable. In obtaining the radiogram, first the system is calibrated by obtaining a blank exposure of the detection panel, that is one without the target present, and using the gain control circuit to generate a flat field output image, i.e. one that has a uniform density throughout the image area. The target is then placed in position and exposed to radiation. The radiation becomes imagewise modulated as it traverses the target and impinges on the detection panel after transiting the grid. The resulting image has been found substantially free of Moirxc3xa9 interference patterns. The same result was obtained whether the grid was stationary during exposure or whether the grid is mounted on a moving support that moves the grid during exposure in a plane substantially parallel to the plane of the detection panel. Those having the benefit of the above disclosure which teaches a grid for limiting scattered radiation from impinging on a radiation detection panel having an array of sensitive areas separated by non radiation sensitive interstitial spaces by designing a grid of radiation opaque areas such that regardless of the placement of the grid relative to the sensitive area array the opaque areas always cover the same amount of area of the sensitive area, may modify this invention in numerous ways to achieve this result. These modifications are to be construed as being encompassed within the scope of the present invention as set forth in the appended claims.
	summary
	claims	1. A specimen observing method based on an electron microscope, comprising:a step of picking up enlarged specimen images by changing focal position of an electron beam in relation to a specimen; a step of image-calculating image sharpness coefficients of the enlarged specimen images; and a step of deciding the number of peaks on a curve indicative of the relation between focal position of the electron beam and image sharpness coefficient, wherein when two peaks are determined to exist in said decision, an astigmatism correction process proceeds, said astigmatism correction process including: a step of picking up enlarged specimen images by changing astigmatism correction current of a stigmator in X direction; a step of image-calculating image sharpness coefficients of the enlarged specimen images; a step of determining a minimum position sandwiched by two peaks on a curve indicative of the relation between the astigmatism correction current of said stigmator in X direction and the image sharpness coefficient; a step of setting the astigmatism correction current of said stigmator in X direction to a current value corresponding to said minimum position; a step of picking up enlarged specimen images by changing astigmatism correction current of a stigmator in Y direction; a step of image-calculating image sharpness coefficients of the enlarged specimen images; a step of determining a minimum position sandwiched by two peaks on a curve indicative of the relation between astigmatism correction current of said stigmator in Y direction and image sharpness coefficient; and a step of setting the astigmatism correction current of said stigmator in Y direction to a current value corresponding to said minimum position. 2. A specimen observing method based on an electron microscope according to claim 1, wherein when two peaks are determined to exist in said decision, said minimum position sandwiched by the two peaks is determined before said astigmatism correction process proceeds and the focal position of the electron beam is set to a position corresponding to said minimum position. 3. A specimen observing method based on an electron microscope, comprising:a step of picking up enlarged specimen images by changing focal position of an electron beam in relation to a specimen; a step of image-calculating an angular direction component of image sharpness coefficient of the enlarged specimen image; a step of deciding an astigmatism correction direction from a result of the calculation of the angular direction component of image sharpness coefficient of said enlarged specimen image; a step of picking up enlarged specimen images by changing the astigmatism correction current of stigmator in said determined direction; a step of calculating image sharpness coefficients of said enlarged specimen images; a step of determining a minimum position sandwiched by two peaks on a curve indicative of the relation between astigmatism correction current of said stigmator and image sharpness coefficient; and a step of setting the astigmatism correction current of said stigmator to a current value corresponding to said minimum position. 4. A specimen observing method based on an electron microscope according to claim 1, wherein a focus correction process proceeds after the astigmatism correction has been completed, said focus correction process including:a step of picking up enlarged specimen images by changing focal position of an electron beam in relation to a specimen; a step of calculating image sharpness coefficients of said enlarged specimen images; a step of determining a peak position on a curve indicative of the relation between focal position of the electron beam and image sharpness coefficient; and a step of setting the focal position of the electron beam to a position corresponding to said peak position. 5. A specimen observing method based on an electron microscope according to claim 1, wherein the image sharpness coefficient is image-calculated in respect of an edge enhanced image of the enlarged specimen image. 6. A specimen observing method based on an electron microscope for performing a process of making the focus of the electron beam coincident with a specimen after a process of correcting astigmatism of the electron beam, wherein a process of making focal position of the electron beam substantially coincident with the specimen before the process of correcting astigmatism of the electron beam, said process of making focal position of the electron beam substantially coincident with the specimen including:a step of picking up enlarged specimen images by changing the focal position of the electron beam in relation to the specimen; a step of calculating pixel mean values of said enlarged specimen images; a step of determining a minimum position on a curve indicative of the relation between the focal position of said electron beam and the pixel mean value; and a step of setting the focal position of said electron beam to a position corresponding to said minimum position, and said process of correcting astigmatism of the electron beam including the individual steps as recited in any one of claims 1 to 3. 7. A specimen observing method based on an electron microscope for performing a process of focusing an electron beam on a specimen after a process of correcting astigmatism of the electron beam, wherein a process of making focal position of the electron beam substantially coincident with the specimen is carried out before the process of correcting astigmatism of the electron beam, said process of making focal position of the electron beam substantially coincident with the specimen including:a step of picking up enlarged specimen images by changing focal position of the electron beam in relation to the specimen; a step of calculating image sharpness coefficients of said enlarged specimen images; a step of calculating pixel mean values of said enlarged specimen images; a step of determining a ratio between the image sharpness coefficient and the pixel mean value at each focal position; a step of determining a maximum position on a curve indicative of the relation between the focal position of the electron beam and the ratio; and a step of setting the focal position of the electron beam to a position corresponding to said maximum position, and said process of correcting astigmatism of the electron beam including the individual steps as recited in any one of claims 1 to 3. 8. A specimen observing method based on an electron microscope according to claim 6, wherein said process of making focal position of the electron beam substantially coincident with said specimen is performed at a lower magnification than a specimen observation magnification. 9. A specimen observing method based on an electron microscope according to claim 1, wherein when setting the astigmatism correction current to a current value corresponding to said minimum position, hysteresis of astigmatism correction current of said stigmator and astigmatism correction amount is taken into account. 10. A specimen observing method based on an electron microscope according to claim 1, wherein the focal position of the electron beam in relation to said specimen is changed by changing excitation current of the objective lens and when setting the focal position of said electron beam to a position corresponding to said minimum position, hysteresis of the excitation current of objective lens and the focal position is taken into consideration. 11. A specimen observing method based on an electron microscope according to claim 1 further comprising a step of, when the number of peaks is determined to be two in said decision, determining an astigmatic difference amount from said two peaks. 12. A specimen observing microscope based on an electron microscope according to claim 11, wherein a range within which said astigmatism correction current is changed is determined on the basis of said astigmatic difference amount. 13. A specimen observing method based on an electron microscope according to claim 11, wherein when the astigmatic difference amount is larger than a predetermined threshold value, said astigmatism correction process proceeds. 14. A specimen observing method based on an electron microscope according to claim 13, wherein measurement of said astigmatic difference amount and said astigmatism correction process are executed repetitively until said astigmatic difference amount becomes smaller than said threshold value. 15. An electron beam apparatus for observing a specimen, the apparatus comprising:an electron microscope for irradiating the specimen with an electron beam and generating enlarged images of the specimen from the electron beam irradiation of the specimen, the electron microscope including a stigmator; and a controller for controlling operation of the electron microscope, configured to cause the electron microscope to implement steps comprising: picking up enlarged specimen images by changing focal position of the electron beam in relation to a specimen; image-calculating image sharpness coefficients of the enlarged specimen images; and deciding the number of peaks on a curve indicative of the relation between focal position of the electron beam and image sharpness coefficient, wherein when two peaks are determined to exist in said decision, an astigmatism correction process proceeds, said astigmatism correction process including: picking up enlarged specimen images by changing astigmatism correction current of the stigmator in X direction; image-calculating image sharpness coefficients of the enlarged specimen images; determining a minimum position sandwiched by two peaks on a curve indicative of the relation between the astigmatism correction current of the stiginator in the X direction and the image sharpness coefficient; setting the astigmatism correction current of the stigmator in the X direction to a current value corresponding to said minimum position; picking up enlarged specimen images by changing astigmatism correction current of the stigmator in Y direction; image-calculating image sharpness coefficients of the enlarged specimen images; determining a minimum position sandwiched by two peaks on a curve indicative of the relation between astigmatism correction current of the stigmator in the Y direction and image sharpness coefficient; and setting the astigmatism correction current of the stigmator in the Y direction to a current value corresponding to said minimum position. 16. An electron beam apparatus for observing a specimen, the apparatus comprising:an electron microscope for irradiating the specimen with an electron beam and generating enlarged images of the specimen from the electron beam irradiation of the specimen, the electron microscope including a stigmator; and a controller for controlling operation of the electron microscope, configured to cause the electron microscope to implement steps comprising: picking up enlarged specimen images by changing focal position of the electron beam in relation to a specimen; image-calculating an angular direction component of image sharpness coefficient of the enlarged specimen images; deciding an astigmatism correction direction from a result of the calculation of the angular direction component of image sharpness coefficient of said enlarged specimen images; picking up enlarged specimen images by changing the astigmatism correction current of the stigmator in said determined direction; calculating image sharpness coefficients of said enlarged specimen images; determining a minimum position sandwiched by two peaks on a curve indicative of the relation between astigmatism correction current of the stigmator and image sharpness coefficient; and setting the astigmatism correction current of the stigmator to a current value corresponding to said minimum position.
053002580	description	DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The need for the present invention was premised on the belief that certain contaminants, particularly those adherent to resins which are or tend to be in contact with soil, present a difficult problem for removal through typical soil-washing processes. The method of the present invention for separation of contaminated resin from soil utilizes the fact that the resins generally have a specific gravity (approximately 1.1 for organic ion exchange resins, e.g.) much lower than that of soil (typically about 2.8). By passing a fluid upflow through a bed of soil and resin, the lower density resin can be readily separated from the soil particles of the same size. Using Stoke's Law, the fluid velocity (i.e., terminal velocity) required to entrain a particle of a particular size can be calculated. During fluid upflow in a solid particle bed, such as in a mineral jig, there occurs fluidization of the solid particles given sufficient fluid velocity. If the fluid velocity exceeds the terminal velocity of the particle, the particle is entrained in the fluid and removed from the bed. The terminal velocity, defined as the velocity eventually attained by a solid particle as it is allowed to fall through a sufficiently high column of a fluid, can be estimated using Stoke's Law: EQU U.sub.t =(p.sub.s -p.sub.f)gd.sup.2 /(18u) where U.sub.t =terminal velocity, cm/sec PA1 p.sub.s =solid density, g/cm.sup.3 PA1 p.sub.f =fluid density, g/cm.sup.3 PA1 g=gravitational acceleration, cm.sup.2 /sec PA1 d=particle diameter, cm PA1 u=fluid viscosity, g-cm/sec for Re.sub.t =U.sub.t dp.sub.f /u<0.3 where Re.sub.t is the particle Reynold's number evaluated at the terminal velocity. For Re.sub.t greater than 0.3 and less than 1000, the following modified expression of Stokes's Law can be used: EQU U.sub.t =0.153d.sup.1.14 g.sup.1.71 (p.sub.s -p.sub.f).sup.0.71 /(u.sup.0.43 p.sub.f.sup.0.29) These equations, while only strictly applicable to spherical particles, are used herein to estimate the terminal velocity for soil and resin particles. The estimated terminal velocity as a function of particle size and particle density are given in Table 1 hereinafter. A comparison of the fluid velocities required for entrainment or fluidization of resin and soil in water as a function of particle size is shown in FIG. 1. It is readily apparent that the resin can be separated from the same size soil particles. However, while removing a particular size resin bead, smaller size soil particles will also be removed. For example, while removing 250 micron resin beads, soil particles 44 micron and smaller will also be removed. Based on the significant size difference between the entrained soil and resin, the overflow stream can be screened to collect the resin beads while allowing the smaller size soil particles to pass through. The method of the present invention thus involves the combination of fluidization of contaminated resin particles and at least a portion of the soil particles at a controlled fluid velocity, and the selective screening of the fluidized effluent. A unique way of achieving this selective separation is with a mining apparatus called a mineral jig (see FIG. 2). The mineral jig as used in the present invention, is operated in a manner which is contrary to its standard use. In a typical ore processing operation, for which the mineral jig is designed, only a relatively minor amount of the highest density fraction of the feed, which is the mineral of interest, is collected in the bottom, or hutch, of the jig. In this normal use, the jig is fed with a slurry through the top, and the jig is pulsed, which induces a pulse on the slurry. Water flows upward through the jig, normally when the pulse is on the down stroke. This pulsing action causes the densest particles to settle more quickly, allowing the lighter, less dense particles to be carried away by the water upflow. TABLE 1 __________________________________________________________________________ Terminal Velocity Estimation for Resin and Soil Particles as a Function of Particle Size Terminal Velocity Solid Particle Screen Rev. No. U.sub.t at Re < 0.3 U.sub.t for 0.3 < Re < 1000 Density Diameter Size Re U.sub.t, U.sub.t, (ps) g/ml (d) (cm) Mesh (IUdp.sub.f /u) cm/sec GPM/ft.sup.2 cm/sec GPM/ft.sup.2 __________________________________________________________________________ SOIL 2.8 0.118 16 226.4 19.2 282.5 132.7 1953.8 2.8 0.071 25 76.3 10.8 158.3 18.0 707.3 2.8 0.060 30 53.2 8.9 130.7 34.3 505.1 2.8 0.025 60 8.2 3.3 48.2 6.0 87.1 2.8 0.015 100 2.7 1.8 26.9 2.1 31.6 2.8 0.009 170 0.9 1.0 15.0 0.8 11.4 2.8 0.005 325 0.2 0.5 6.8 0.2 2.8 RESIN 1.1 0.118 16 29.7 2.5 37.0 7.6 111.6 1.1 0.071 25 10.0 1.4 20.7 2.7 40.4 1.1 0.060 30 7.0 1.2 17.1 2.0 28.9 1.1 0.025 60 1.1 0.4 6.3 0.3 5.0 1.1 0.015 100 0.4 0.2 3.5 0.1 1.8 1.1 0.009 170 0.1 0.1 2.0 0.0 0.6 1.1 0.005 325 0.0 0.1 0.9 0.0 0.2 __________________________________________________________________________ NOTES: a) To calculate U.sub.t at Re < 0.3, U.sub.t = 0.153d.sup.(1.14) g.sup.(0.71) p(p - p.sub.f.sup.(0.71) /u.sup.(0.43) p.sub.f.sup.(0.29) b) To calculate U.sub.t for 0.3 < Re < 1000, U.sub.t = (p.sub.s - p.sub.f)gd; < (18u). c) It is assumed that only half of the jig area is available to flow (i.e., 50% screen area). d) pf = fluid density = 1 g/ml; g = gravitational acceleration = 980 u = fluid viscosity = 0.01 gcm/sec The operation of the jig for the resin segregation application of the present invention, however, is modified so that a majority of the soil passes downflow through the jig, and only the resin and soil fines are carried over. This is accomplished by setting a relatively long stroke in the jig, giving the particles more time to settle before the next pulse and by minimizing the bed depth in the jig, preferably using oversized particles in the bed, and using a continuous upflow. In this way, it is actually possible to entrain the resin particles at a fluid velocity lower than the theoretical entrainment velocity. The overflow containing resin and fines is then screened to separate the resin from the fines. Referring to FIG. 2, a preferred method of practicing the invention is illustrated. A mixture of contaminated soil, which contains resin, generally 10, is slurried in any known manner, for example, by blending the mixture with water in a slurry tank 11. This resin/soil mixture may be the product of an accidental resin spill or may be the product of resin which has been intentionally introduced to the soil to remove contaminants from the soil. Fluids other than water could of course be used to form the slurry, such as other liquids (oil, e.g.). Also, gases (such as air, e.g.), can be used to fluidize the resin. The slurry is fluidized such that the slurry achieves a velocity required to entrain substantially all of the resin particles and a portion of the soil particles, generally the fines. However, the fluid velocity should not be so great as to entrain the entire mixture of soil and resin, or the advantages of separation according to the present invention will be compromised. Over-entrainment would further result in wasted energy. The slurried mixture may be entrained in any known way, provided the desired terminal or entrainment velocity is reached. Entrainment methods may include the use of pumps, gravity (by developing sufficient head to provide the desired terminal velocity downstream), stirrers, blowers, etc. The entrained resin and soil are separated from those soil particles which have not been entrained in the fluid. The simplest way of doing this is to allow the soil particles which have not been entrained to settle out by gravity and be collected. This is illustrated schematically in FIG. 2, by the slurried mixture, 12, entering the jig, 13, which is fed with jig water 14. The soil particles which have not been entrained by the jig 13, settle out 15, and are collected as clean soil in a product carboy 16. Meanwhile, the overflow 17, which passes upflow from the jig 13, has achieved terminal or entrainment velocity and has entrained the resin and at least a portion of the soil, typically fines, is passed through particle size separation means sized to recover the resin, such as a 60 mesh screen 18. The contaminated resin 19 is removed for disposal, thermal destruction, oxidation of contaminants, recovery of heavy metals and the like. The soil-containing stream 20 passes through the particle size separation means resin free and is collected in a hopper 21 for return to the site or further processing. The ability to accomplish the desired resin segregation using this approach is demonstrated in the following example. EXAMPLE Remediation studies on a soil from a uranium solution mining site in Bruni, Tex. had shown that resin contamination was present in certain soil samples. Extractants that were successful at removing the uranium contamination from just soils, were no longer effective on the soils that contained the resin. This was due to the fact the resin (DOWEX 21K, Rohm and Haas, Philadelphia, Pa.) has a high affinity for the uranium, which could not be mobilized by extractants. Chemical analysis of the soil and resin mixture showed the uranium content to be approximately 90 ppm, which is above the required remediation level of 42 ppm. Further analysis showed that a majority of the contamination was associated with the resin. The resin, which represented about 1 weight percent of the soil mixture, contained 7000 ppm uranium. The soil itself contained less than 30 ppm uranium. As shown in FIG. 3, to achieve the desired uranium level in the soil it was thus necessary to segregate at least 70% of the resin from the soil. A particle size analysis of the resin showed that a majority of the resin was greater than 250 microns. Tests were thus run to determine if the resin could be segregated from the soil using a mineral jig to fluidize the resin and a 250 micron screen to collect the resin from the overflow. The results of the tests, summarized in Table 2, show that under conditions which are run to maximize solid downflow through the jig (Test A), only about 40% of the resin was removed from the soil. Subsequent testing showed that by adding a bed of oversized soil particles the segregation could be greatly improved. The oversized bedding soil was sized (0.19 to 0.25 inch diameter) to prevent its discharge from the bed by entrainment in the overflow stream, but to still allow adequate pulsing of the bed and thus allow the soil being processed to pass through the interstices in the bed. The bedding provides a more tortuous path for the resin to travel to the bottom of the jig, and thus provides much greater opportunity for the resin to be fluidized from the soil by the upflow stream. The bedding also results in better distribution of the solution flow up through the jig, thus minimizing channelling. The results of Table 2 show that with .the use of oversized bedding material, resin segregation of 80% and greater was achieved. The mineral jig may have a stroke length of up to 0.75 inch with a frequency of 800 rpm. The fluidizing zone of the jig may have dimensions of about 4".times.6" to 4 feet.times.6 feet in surface area with a height of up to about a foot. The important variable for fluidization is flow rate per unit surface area of the zone. The results of Table 2 also show that the resin segregation can be increased from 80% (Test B) to greater than 90% (Test C) by increasing the upflow rate from 1.6 to 3.2 GPM/ft.sup.2. Increasing the flow further to 4.8 GPM/ft.sup.2 (Test D) did not significantly increase the resin removal. According to Stoke's Law, fluid velocities of at least 5 GPM/ft.sup.2 should have been required to entrain this resin. The pulsing action of the jig and the short fluidization zone in the jig is believed to result in the lower fluid flow rates being required for resin entrainment. Other separation devices (e.g., fluidized beds) will require greater flow rates to achieve the same degree of resin segregation. Analysis of the soil products, which are the jig bottoms and the jig overflow which passed through the screen (<250 microns), contained less than 30 ppm uranium. These streams represented .about.99% of the feed; thus the contamination was effectively concentrated in 1% of the feed which was collected in the overflow 250 micron screen. TABLE 2 ______________________________________ Resin Segregation Particle % Resin Test # upflow Rate Bed* Removed ______________________________________ A 4.8 GPM/ft.sup.2 No 43% B 1.6 GPM/ft.sup.2 Yes 80% C 3.2 GPM/ft.sup.2 Yes +90% D 4.8 GPM/ft.sup.2 Yes +90% ______________________________________ *Layer of solids in particle bed comprise 0.19-0.25 inch diameter solids. It will, of course, be appreciated by those skilled in the art that variations to the method of the invention disclosed herein may be practiced without departing from the spirit of the invention as set forth in the following claims. For example, the method of the invention may be used to remove any type of resin containing contaminants from soil, including those resins containing anions. Such anions may include, for example, complexes of uraninium, arsenic and/or chromium, which tend to carry an anionic charge. Of course, cationic exchange resins may also be removed from the soil according to the present invention.
059011939	summary	TECHNICAL FIELD The invention relates to the field of nuclear fuel for pressurized-water reactors, wherein the nuclear fuel comprises cladding tubes built up of two layers, an inner supporting layer of a conventional zirconium alloy and an outer layer of a zirconium alloy with improved corrosion properties. BACKGROUND OF THE INVENTION It is known that a nuclear fuel for pressurized-water reactors may comprise cladding tubes built up of two layers. EP 301 295 describes nuclear fuel elements with cladding tubes with an inner supporting part of zirconium with 1.2 to 2% Sn, 0.07 to 0.2% Fe, 0.05 to 0.15% Cr, 0.03 to 0.08% Ni and 0.07 to 0.15% O or zirconium with 1.2 to 2.0% Sn, 0.18 to 0.24% Fe, 0.07 to 0.13% Cr and 0.10 to 0.16% O. The outer layer shall be of a zirconium alloy with better corrosion resistance than the inner part of the tube and is described to comprise either one or more of the alloying additives Sn, Fe, Cr, or Ni in a total amount being less than 1%, or one or more of the alloying additives Sn, Fe, Cr or Ni in a total amount less than 1% and 0.2 to 3% Nb. The described examples of outer layers with the above composition and improved corrosion properties are zirconium with 2.5 Nb and zirconium with 0.25% Sn, 0.5% Fe and 0.05% Cr. A problem which arises with a cladding according to EP 301 295 is due to the great difference in Sn content which exists between the inner part, which has 1.2 to 2% Sn, and the outer layer with 0.25% Sn. Since the Sn content influences the recrystallization temperature of the zirconium alloy, the cladding will after the final heat treatment, which for pressurized-water fuel usually is a stress-relieve anneal, have an inner part which is stress-relieve-annealed and an outer part which is recrystallization-annealed. Such a difference in state between the inner part and the outer layer leads to different hydride orientation in these parts and to accumulation of hydrides at the boundary layer between the parts. Hydrides in the cladding material occur due to hydrogen developed during the corrosion of zirconium during reactor operation being taken up to a certain part by the cladding material, and since zirconium has low solubility of hydrogen, the absorbed hydrogen will be precipitated in the form of zirconium hydrides. These are elongated in shape and very brittle. During the manufacture of cladding tubes for nuclear fuel elements, it is therefore important to see to it that hydrides which are precipitated in the cladding material are evenly spread in the material and tangentially distributed in the cross section. The hydrides are very brittle and may act as indications of fracture. It is therefore important that the hydrides are precipitated tangentially in the cross section of the tube and that there are very few radially directed hydrides which may act as indications of a crack through the cladding wall. Nuclear fuel with a cladding consisting of two layers is also known from WO 93/18520. This describes a two-layer cladding, where both layers contain the same alloying elements to facilitate the handling of material returned from the manufacturing process, and whereof these are at least Sn, Fe and Cr. The supporting inner layer comprises 1-2% Sn, 0.05-0.25% Fe, 0.05-0.2% Cr to the outer layer 0.5-1.3% Sn, 0.15-0.5% Fe and 0.05-0.4% Cr and to obtain improved workability and bonding between the layers during the manufacturing of the cladding, the ratio between the contents of Sn in the outer layer and the inner layer shall be within the interval 0.35 to 0.7 and the content of Sn in the inner layer shall be two to five times the content of Fe and Cr in the outer layer. The problem with this kind of nuclear fuel is that also for these layers, there may be great differences in the Sn content between the outer and inner layers. The outer layer in WO 93/18520 is stated to contain, besides Sn, Fe and Cr and then preferably 0.28.+-.0.04% Fe and 0.17.+-.0.03% Cr in order not to obtain an alloy which is difficult to work. An example given is zirconium with 1.1% Sn, 0.4% Fe and 0.25% Cr. Other known fuel elements with a two-layer cladding are described in EP 212 351 which shows an outer layer consisting of zirconium with additives of Fe, V, Pt or Cu. EP 380 381 describes outer layers of zirconium with 0.35 to 0.65% Sn, 0.2 to 0.65% Fe, 0.24 to 0.35% Nb.
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	description	The present invention relates generally to the welds between that connect some components of a nuclear reactor pressure vessel; and more particularly to an apparatus and system for replacing the welds between components. A non-limiting example of a nuclear reactor, a conventional boiling water reactor (BWR) is shown in FIGS. 1-3. A typical BWR includes: a reactor pressure vessel (RPV) 10, a core shroud 30 disposed within the RPV 10, and a nuclear fuel core 35. The core shroud 30 is a cylinder that surrounds the nuclear fuel core 35, which includes a plurality of fuel bundle assemblies 40 disposed within the core shroud 30. A top guide 45 and a core plate 50 supports each of the fuel bundle assemblies 40. An annular region between the core shroud 30 and the RPV 10 is considered the downcorner annulus 25. Coolant water flows through the downcorner annulus 25 and into the core lower plenum 55. Feedwater enters the RPV 10 via a feedwater inlet 15 and is distributed circumferentially within the RPV 10 by a feedwater sparger 20, which is adjacent a core spray line 105. Then, the water in the core lower plenum 55 flows upward through the nuclear fuel core 35. In particular, water enters the fuel bundle assemblies 40, wherein a boiling boundary layer is established. A mixture of water and steam exits the nuclear fuel core 35 and enters the core upper plenum 60 under the shroud head 65. The steam-water mixture then flows through standpipes 70 on top of the shroud head 65 and enters the steam separators 75, which separate water from steam. The separated water is recirculated to the downcorner annulus 25 and the steam exits the RPV 10 via a nozzle 110 for use in generating electricity and/or in another process. As illustrated in FIG. 1, a conventional jet pump assembly 85 comprises a pair of inlet mixers 95. Each inlet mixer 95 has an elbow welded thereto, which receives pressurized driving water from a recirculation pump (not illustrated) via an inlet riser 100. Some inlet mixers 95 comprise a set of five nozzles circumferentially distributed at equal angles about an axis of the inlet mixer 95. Here, each nozzle is tapered radially and inwardly at the nozzle outlet. This convergent nozzle energizes the jet pump assembly 85. A secondary inlet opening (not illustrated) is located radially outside of the nozzle exit. Therefore, as jets of water exit the nozzles, water from the downcorner annulus 25 is drawn into the inlet mixer 95 via the secondary inlet opening, where mixing with water from the recirculation pump occurs. The BWR also includes a coolant recirculation system, which provides the forced convection flow through the nuclear fuel core 35 necessary to attain the required power density. A portion of the water is drawn from the lower end of the downcorner annulus 25 via a recirculation water outlet 80 and forced by the recirculation pump into a plurality of jet pump assemblies 85 via recirculation water inlets 90. The jet pump assemblies 85 are typically circumferentially distributed around the core shroud 30 and provide the required reactor core flow. A typical BWR has between sixteen to twenty-four inlet mixers 95. Typically, each jet pump assembly 85 includes at least the following. A transition piece 120, a riser pipe 130 extending downwardly from the transition piece 120 to an riser elbow 135. The riser elbow 135 connects the riser pipe 130 to a recirculation inlet 90 along a wall of the RPV 10. A pair of inlet mixers 95 extends downwardly from the transition piece 120 to a pair of diffusers 115 mounted over holes in a pump deck 125. The pump deck 125 connects a bottom portion of the core shroud 30 with the RPV 10. The riser pipe 130 is typically tubular and is oriented vertically within the downcorner annulus 25, in parallel relation to the wall of the core shroud 30. The riser elbow 135 is typically tubular and bends outwardly toward the recirculation inlet 90. The transition piece 120 extends in opposite lateral directions at the top of the riser pipe 130 to connect with the inlet mixers 95 on opposite sides of the riser pipe 130. The inlet mixers 95 are oriented vertically in the downcorner annulus 25 in parallel relation to the riser pipe 130. Restrainer brackets 140, located between the inlet mixers 95 and the riser pipe 130, provide lateral support for the inlet mixers 95. Typically, the riser pipe 130 is supported and stabilized within the RPV 10 by a riser brace 145 (illustrated, for example, in FIG. 2) attached to the riser pipe 130 and to an attachment wall 149, which is typically a wall of the RPV 10. Commonly, the riser brace 145 is attached to the riser pipe 130 and to the attachment wall 149 by welding. The riser brace 145 ordinarily comprises a yoke 143 (FIG. 3) and side members 147 extending respectively from opposite ends of the yoke 143 in a spaced parallel relation. Typically, the yoke 143 has an inwardly curved surface between the side members 147, which is complementary to the outer curvature of the exterior surface of the riser pipe 130. The riser brace 145 is disposed in the downcomer annulus 25 with the riser pipe 130 disposed between the side members 147. The riser brace 145 is normally attached to the riser pipe 130 via a weld between the inwardly curved surface and the exterior surface of the riser pipe 130. Here, the side members 147 generally transverse to the riser pipe 130 and extend from the yoke 143 and respective ends of the side members 147 attach to the attachment wall 149. The ends of the side members 147 are normally welded to the attachment wall 149. Alternatively, the ends of the side members 147 may be welded to an intermediary structure, such as, but not limiting of, braces, blocks or pads, with the intermediary structure being in turn welded to the attachment wall 149. Typically, each side member 147 comprises an upper leg and a lower leg disposed beneath the upper leg in spaced parallel relation therewith. The riser brace 145 generally provides lateral and radial support to the riser pipe 130. In addition, the riser brace 145 is designed to accommodate the differential thermal expansion resulting from RPV 10 operation, and to accommodate for flow-induced vibrations associated with the reactor water circulation system. Intergranular stress corrosion cracking (IGSCC) resulting from corrosion, radiation and/or stress may occur in the welds between the riser braces 145 and the riser pipes 130 of jet pump assemblies 85 of an RPV 10. Cracks initiated by IGSCC or other causes in the welds between the riser braces 145 and the riser pipes 130 may grow to critical sizes for mechanical fatigue resulting from the vane passing frequencies of the recirculation pumps exceeding the excitation frequency of the riser braces 145. To avoid resonance, the natural frequency of the riser brace 145 should not be nearly equal to the vane passing frequency of the recirculation pumps (at any pump speed). If the vane passing frequency of the recirculation pumps equals or exceeds the natural frequency of the riser brace 145, then the riser brace 145 may potentially enter resonance; possibly to the detriment of the jet pump assembly 85. A clamp apparatus for mechanically reinforcing the weld between a riser pipe and a riser brace is disclosed in U.S. Pat. No. 7,185,798 B2 to Butler. Here, the clamp apparatus augments the welded connection between the riser brace and the riser pipe. A clamp apparatus for stiffening a riser brace of a jet pump assembly 85 is disclosed in U.S. Pat. No. 6,647,083 B1 to Jensen. Here, the clamp apparatus is applied to the side members of the riser brace to shorten portions of the side members subject to vibration. The clamp apparatus does not attach to the riser pipe and does not augment the welded connection between the riser brace and the riser pipe. Various clamps used in jet pump assemblies of boiling water reactors are represented by U.S. Pat. No. 6,463,114 B1 to Wivagg, U.S. Pat. No. 6,490,331 B2 to Erbes, U.S. Pat. No. 6,450,774 B1 to Erbes et al, U.S. Pat. Nos. 6,086,120 and 6,053,652 to Deaver et al, and U.S. Pat. No. 6,108,391 to Deaver. The Wivagg patent discloses a clamp used in conjunction with a jacking device to restrain the existing jack screws that are welded about the peripheries of the inlet mixers to provide lateral restraint for the inlet mixers within the restrainer brackets. The Erbes ('331) patent relates to a spring clamp for providing a tight fit between an inlet mixer 95 and a restrainer bracket. The Erbes et al ('120) patent discloses a clamp for being installed on a slip joint coupling an inlet mixer to a diffuser. The clamp is used to squeeze the diffuser to impart an oval deformation to the diffuser. The Deaver et al patents ('120 and '652) disclose a clamp apparatus for supporting the lower portion of a riser of a jet pump assembly. The clamp apparatus comprises an elbow clamp, a riser clamp and a bridge coupling the elbow and riser clamps. The riser clamp includes a pair of legs for being disposed on opposite sides of the riser pipe and a back portion rigidly connecting the legs in fixed relation. The Deaver ('391) patent relates to a clamp having upper and lower clamp elements receiving the outer end of a riser elbow between the upper and lower clamp. There are a few possible problems with the currently known apparatuses, methods, and systems for dampening the vibration experience by the riser pipe 130. Currently known solutions require re-welding or integrate with existing welds, which may lead to a repeat failure. These apparatuses, methods, and systems also generally require longer installation time and expose operators to longer period of radioactivity. These apparatuses, methods, and systems may comprise many parts, which increase the assembly and installation time. Based on the above discussion, operators of nuclear power plants may desire an apparatus and system for reinforcing the connection between a riser pipe 130 and a riser brace 145 of a jet pump assembly 85. The apparatus and system should not require welds between the riser pipe 130 and the riser brace 145. The apparatus and system should reduce a level of vibration experienced by the riser pip 130. The apparatus and system should require few parts allowing for a relatively quick assembly and installation. In accordance with an embodiment of the present invention, an apparatus for integrating a riser brace with an inlet riser of a jet pump assembly, wherein the inlet riser comprises a central longitudinal axis and the riser brace comprises first and second side members extending from a yoke which engages a portion of the inlet riser, and wherein the first and second side members extend transversely to the central longitudinal axis on opposite sides of the inlet riser, the apparatus comprising: a) a saddle for securing a position an inlet riser of a pressure vessel within a yoke of a riser brace, wherein the saddle comprises: an engagement surface for radially supporting a portion of the inlet riser, wherein the engagement surface allows for mating with the portion of the inlet riser; and a connection structure for maintaining a position of the engagement surface, wherein the connection structure is integrated with a portion of the engagement surface; and h) a securing structure for connecting the saddle to the riser brace, wherein the securing structure anchors the saddle to the inlet riser. In accordance with another embodiment of the present invention, a system for dampening a level of vibration experienced by an object integrated within a nuclear power plant; the system comprising: a reactor pressure vessel (RPV); an inlet riser of a jet pump assembly within the RPV, wherein the inlet riser comprises a central longitudinal axis and the riser brace comprises first and second side members extending from a yoke which engages a portion of the inlet riser, and wherein the first and second side members extend transversely to the central longitudinal axis on opposite sides of the inlet riser; a saddle for securing a position the inlet riser within the yoke of the riser brace, wherein the saddle comprises: an engagement surface for radially supporting a portion of the inlet riser, wherein the engagement surface allows for mating with the portion of the inlet riser; and a connection structure for maintaining a position of the engagement surface, wherein the connection structure is integrated with a portion of the engagement surface; and a securing structure for connecting the saddle to the riser brace, wherein the securing structure anchors the saddle to the inlet riser. Certain terminology may be used herein for convenience only and is not to be taken as a limitation on the invention. For example, words such as “upper”, “lower”, “left”, “front”, “right”, “horizontal”, “vertical”, “upstream”, “downstream”, “fore”, and “aft” merely describe the configuration shown in the FIGS. Indeed, the components may be oriented in any direction and the terminology, therefore, should be understood as encompassing such variations unless specified otherwise. As used herein, an element or step recited in the singular and preceded with “a” or “an” should be understood as not excluding plural elements or steps, unless such exclusion is explicitly recited. Furthermore, references to “an embodiment” of the present invention are not intended to exclude additional embodiments incorporating the recited features. The following discussion focuses on an embodiment of the present invention integrated with the jet pump assemblies 85 of the RPV 10. Other embodiments of the present invention may be integrated with other systems that require a dampening of and/or frequency change in vibration. The present invention takes the form of an apparatus or system that may reduce the level of vibration experienced by an inlet riser 100 or other similar object within a RPV 10. An embodiment of the present invention may eliminate the need for welding the riser brace 145 to the inlet riser 100. An embodiment of the present invention provides at least one riser brace clamp 150 that generally clamps the riser brace 145 to the inlet riser 100. After installation, the riser brace clamp 150 may lower the amplitude of, and/or change the frequency of, the vibration experienced by the inlet riser 100. Referring again to the FIGS., where the various numbers represent like parts throughout the several views. FIGS. 2 and 3 are schematics illustrating isometric and side views of a typically jet pump assembly 85 of a RPV 10. FIG. 2 is a schematic, illustrating the jet pump assembly 85 portion of the boiler water reactor of FIG. 1. FIG. 3 is a schematic, illustrating a side view of the jet pump assembly 85 of FIG. 2, partially in cross-section. As discussed, the jet pump assembly 85 of the RPV 10 is generally disposed in the downcorner annulus 25 located between the RPV 10 and the core shroud 30. Generally, the jet pump assembly 85 comprises: a transition piece 120; an inlet riser 100 extending downwardly from the transition piece 120 to a recirculation inlet 90 along the exterior of a wall of the RPV 10; and a pair of inlet mixers 95 extending downwardly from the transition piece 120 to a pair of diffusers 115 mounted over holes in a pump deck 125, which connects a bottom portion of the core shroud 30 with the RPV 10. The inlet riser 100 generally includes: a tubular riser pipe 130 extending vertically and downwardly within the downcorner annulus 25 in parallel relation to the wall of the core shroud 30; and a tubular riser elbow 135 extending downwardly from the bottom of the inlet riser 100 and bending outwardly toward the recirculation inlet 90. The inlet riser 100 is ordinarily cylindrical and tubular with a longitudinally straight configuration between transition piece 120 and elbow 135. The outer end of the elbow 135 may be connected with a thermal sleeve in the recirculation inlet 90. The transition piece 120 may extend in opposite lateral directions at a top of the inlet riser 100 to connect with the inlet mixers 95 on opposite sides of the inlet riser 100. The inlet mixers 95 are typically oriented vertically in the downcorner annulus 25, in parallel relation to the inlet riser 100. Restrainer brackets 140 may be attached between the inlet mixers 95 and the inlet riser 100; and may provide lateral support for the inlet mixers 95. A riser brace 145 may support and stabilize the inlet riser 100 in the region of the downcomer annulus 25. The riser brace 145 may also integrate the inlet riser 100 with an attachment wall 149 of the RPV 10. An embodiment of the riser brace 145 may generally have a U-shaped configuration. Here, the riser brace 145 may comprise a yoke 143 and first and second side members 147; which may extend in the same direction from opposite ends of the yoke 143 in a spaced parallel relation to terminate at respective side member ends 147. The periphery or footprint of the riser brace 145 may comprise an outer peripheral portion of generally U-shaped configuration, an inner peripheral portion of generally U-shaped configuration within the outer peripheral portion, and end peripheral portions connecting the outer and inner peripheral portions. An embodiment of the present invention provides a riser brace clamp 150, which serves to connect the inlet riser 100 and the riser brace 145. As illustrated, for example in FIG. 5, an embodiment of the riser brace clamp 150 may fit around and clamp the riser brace 145 to the inlet riser 100. Essentially, an embodiment of the riser brace clamp 150 comprises a saddle 155 and a securing structure 165, such as, but not limiting of, a riser clamp bracket 165. The securing structure 165 may connect the saddle 155 to the riser brace 145. Furthermore, in use, the securing structure 165 may anchor the saddle 155 to the inlet riser 100. FIG. 4 is a schematic illustrating an exploded isometric view of an embodiment of a riser brace clamp 150 in accordance with an embodiment of the present invention. As illustrated in FIG. 4, an embodiment of the present invention may comprise the following components. A saddle 155, two (2) fasteners 160, and two (2) riser clamp brackets 165, which collectively function as the aforementioned securing structure 165. In an embodiment of the present invention, the saddle 155 may comprise an engagement surface(s) 157 and a connection structure (s) 159. The engagement surface 157 may serve to radially support a portion of the inlet riser 100 that may be engaging the yoke 143 of the riser brace 145. The engagement surface 157 may face an outer diameter of the inlet riser 100. The engagement surface 157 may be formed in a shape that allows for direct or indirect mating with the outer diameter of the inlet riser 100. For example, but not limiting of, if the inlet riser 100 is of a cylindrical shape, then the engagement surface 157 may have an arc or semi-circular shape having a similar radius as the outer diameter of the inlet riser 100, as illustrated in FIGS. 4-6. The connection structure 159 may serve as the area(s) that allow the saddle 155 to be connected to the securing structure 165 of the repair brace clamp 150. The connection structure 159 may comprise a plurality of forms, such as, but not limiting of, a land, a boss, or any other surface integrated with the engagement surface 157 that allows for the position of the saddle 155 to be secured. In an embodiment of the present invention, the connection structure 159 may comprise the form of a first and a second connection surface 159. The first connection surface 159 may be located adjacent to an end of the engagement surface 157 and substantially parallel to the second connection surface 159, which may also be located adjacent to another end of the engagement surface 157. Here, each connection surface 159 may comprise at least one hole, as illustrated in FIG. 4, which allows for the saddle 155 to integrate with each riser clamp bracket 165. In an embodiment of the present invention, the first and the second riser clamp brackets 165 may integrate with the riser brace 145 and allow for the saddle 155 to integrate with the same. Each riser clamp bracket 165 may comprise a mating shaft. The mating shaft generally allows for the few components of the repair brace clamp 150 to assemble. The mating shaft maybe positioned at a mounting position for mating with each hole on the connection surface 159 of the saddle 155. In an embodiment of the present invention each riser clamp bracket 165 may comprise a one-piece structure, as illustrated in FIGS. 4 and 5. In an alternate embodiment of the present invention each riser clamp bracket 165 may comprise a multi-piece structure. Here, and as illustrated in FIG. 6, the riser clamp bracket 165 may comprise a base 175 and an arm 180. The base 175 may be slidably connected to a portion of the riser brace 145. The arm 180 may comprise the mounting shaft and may connect to the base 175 as illustrated. The fasteners 160 generally serve to connect the saddle 155 to the riser brace 145. In use, the fasteners 160 may anchor the inlet riser 100 to the yoke 143 of the riser brace 145. An embodiment of the fastener 160 make comprise a nut have a crimp collar portion. This may prevent the fastener 160 from loosening after the saddle 155 is in a desired position. FIG. 5 is a schematic illustrating a plan view of a riser brace clamp 150 installed on an inlet riser 100, in accordance with an embodiment of the present invention. Specifically, FIG. 5 illustrates a front isometric view of the riser brace 145. As illustrated, an embodiment of the present invention provides a relatively simple apparatus that may be quickly assembled and installed. First, the riser clamp brackets 165 may be connected to a rear portion of the riser brace 145. Next, the saddle 155 may be installed wherein the engagement surface 157 mates with the outer diameter of the inlet riser 100. Lastly, the fasteners 160 may secure the position on the repair brace clamp 150 to the repair clamp 200. FIG. 6 is a schematic illustrating a plan view of a riser brace clamp 150 installed on an inlet riser 100, in accordance with an alternate embodiment of the present invention. Here, the base 175 may slide over a portion of the riser brace 145 and the arm 180 may then integrate with the base 175. This embodiment may allow for a rapid installation of the repair brace clamp 150, which may not require the removal of the riser brace 145 or the inlet mixer 95. The components of an embodiment present invention may be formed of any material capable of withstanding the operating environment to which the riser brace clamp 150 may be exposed. In use, the riser brace clamp 150 may clamp around the inlet riser 100 and the riser brace 145 at a location of the previous welds. When fully engaged, the riser brace clamp 150 may provide for generous clearance around the inlet riser 100. The riser brace clamp 150 may also reduce the vibration experience by the inlet riser 100. Although the present invention has been shown and described in considerable detail with respect to only a few exemplary embodiments thereof, it should be understood by those skilled in the art that we do not intend to limit the invention to the embodiments since various modifications, omissions and additions may be made to the disclosed embodiments without materially departing from the novel teachings and advantages of the invention, particularly in light of the foregoing teachings. Accordingly, we intend to cover all such modifications, omissions, additions and equivalents as may be included within the spirit and scope of the invention as defined by the following claims. For example, but not limiting of, an embodiment of the present invention may be used to: a) introduce a different vibration mode; b) to secure a pipe, cable, wire, or other similar object, at a fixed distance away from a separate structure or other object; or c) to apply a compressive load to at least one of the aforementioned objects.
	abstract	The invention is directed to improved containers for pharmaceuticals and any tubing and tubing connectors associated therewith, particularly containers for pharmaceuticals which are irradiated, heated or otherwise subjected to increased pressure. In a preferred embodiment, the invention is directed to an improved container for use in a radioisotope generator, such as a rubidium-82 generator.
054209021	claims	1. A fuel assembly, comprising: a cluster of mutually parallel fuel rods; a fuel assembly channel laterally surrounding said cluster of fuel rods and having a substantially rectangular cross section and flat channel walls; grid-like spacers having meshes formed therein each receiving a respective one of said fuel rods for guiding said fuel rods in a plurality of axial positions; at least one support spring laterally supporting each respective one of said fuel rods in said mesh guiding said fuel rod; each of said spacers having inner ribs being aligned parallel to said fuel rods and outer peripheral ribs opposite said channel walls, at least some of said inner ribs being fastened to said peripheral ribs, and said outer peripheral ribs being joined together substantially exclusively by said inner ribs. an approximately central coolant pipe; a cluster of mutually parallel fuel rods surrounding said coolant pipe and defining interstices therebetween; a channel laterally surrounding said cluster of fuel rods and having walls; a grid-like spacer having meshes for guiding said fuel rods, outer peripheral ribs opposite said walls of said channel, inner peripheral ribs substantially resting on said coolant pipe, and inner ribs joining said outer ribs to said inner peripheral ribs, said outer peripheral ribs and said inner peripheral ribs having upper edges; support springs laterally supporting said fuel rods in said meshes; rings of tabs disposed on said respective upper edges of said outer peripheral ribs and said inner peripheral ribs and bent into said interstices between the fuel rods adjacent said peripheral ribs, all of said tabs having upper edges disposed in an upper plane, all of said ribs having lower edges disposed in a lower plane, and said upper edges of said outer peripheral ribs being lower than said upper edges of said inner peripheral ribs between said tabs. a) upper and lower bearing surfaces resting on a front side of the inner rib; b) two flat legs each adjoining a respective one of said bearing surfaces; c) a singly bent, resilient middle part facing toward said one fuel rod and joining said two flat legs together; and d) spring ends each merging with a respective one of said two bearing surfaces, said spring ends being fastened to one another for completely encompassing the inner rib with said support spring; wherein the front side of the inner rib has a protrusion facing toward said resilient middle part. a) upper and lower bearing surfaces resting on a front side of the inner rib; b) two flat legs each adjoining a respective one of said bearing surfaces; c) a singly bent, resilient middle part facing toward said one fuel rod and joining said two flat legs together; and d) spring ends each merging with a respective one of said two bearing surfaces, said spring ends being fastened to one another for completely encompasses the inner rib with said support spring; e) wherein the front side of the inner rib has a protrusion facing toward said resilient middle part. 2. The fuel assembly according to claim 1, wherein each of said inner ribs is a can forming one of said meshes surrounding and guiding one said fuel rods, and said cans for said fuel rods adjacent to said outer peripheral ribs are welded to said outer peripheral ribs. 3. The fuel assembly according to claim 1, for a boiling water nuclear reactor, including knobs supporting said outer peripheral ribs against said channel walls, said knobs having halves being mirror images of one another, said ribs having ends, each of said ribs resting on said channel wall, through one of said halves of said knob on one of said ends of said rib and through the other of said halves of said knob on the other of said ends of said rib. PG,24 4. A fuel assembly for a boiling water reactor, comprising: 5. The fuel assembly according to claim 4, wherein said coolant pipe has stops engaging between said tabs of said inner peripheral ribs and coming to a stop against the upper edges of said inner peripheral ribs, substantially without touching said inner ribs. 6. The fuel assembly according to claim 5, wherein said stops are disposed only at two diametrically opposed locations on said coolant pipe. 7. The fuel assembly according to claim 4, wherein at least two of said tabs abut at locations at which they are laterally welded together. 8. The fuel assembly according to claim 4, wherein said coolant pipe has a wall, each of said inner peripheral ribs has an upper and a lower peripheral part being constructed as a contact part pointing away from the coolant pipe wall and springing back toward one of said fuel rods, and a can-like inner rib forming a mesh and being fastened on said peripheral parts. 9. The fuel assembly according to claim 4, wherein said coolant pipe has a wall, each of said inner peripheral ribs has upper and lower peripheral parts, a middle part between said upper and the lower peripheral parts, and a spacer element resting on said middle part and supporting said peripheral rib against the coolant pipe wall. 10. The fuel assembly according to claim 9, wherein said spacer element is a spacer spring resting on said middle part and being supported against the coolant pipe wall. 11. The fuel assembly according to claim 1, wherein said support springs are each held by an inner rib having a front side facing toward one of said fuel rods and include: 12. The fuel assembly according to claim 4, wherein said support springs are each held by an inner rib having a front side facing toward one of said fuel rods;
062122525	claims	1. An X-ray mask comprising: a substrate; a membrane formed on said substrate and allowing passage of X-rays; and an X-ray absorber formed on said membrane and intercepting transmission of X-rays, wherein a protective film arranged between said substrate and said X-ray absorber. forming a membrane allowing passage of X-rays on a substrate; forming an X-ray absorber intercepting transmission of X-rays on said membrane; forming a window exposing said membrane in said substrate; forming a first mask layer on said X-ray absorber; writing a first mask pattern on said first mask layer; effecting development on said first mask layer to form a first mask pattern layer; removing said X-ray absorber using said first mask pattern layer as a mask, and thereby forming an opening functioning as an alignment mark in a region not overlapping with said opening in a plan view. removing said first mask pattern layer; forming a second mask layer on said X-ray absorber; writing a second mask pattern on said second mask layer while performing position detection of said second mask layer using said opening as the alignment mark; effecting development on said second mask layer to form a second mask pattern layer; and removing said X-ray absorber to form a transfer circuit pattern, using said second mask pattern layer as a mask. said step of writing said first mask pattern includes an exposure step using light, and said step of writing said second mask pattern includes a writing step using an electron beam. said step of forming said second mask layer includes a step of forming a second mask layer exposing said opening on said X-ray absorber. said step of forming said opening include a first etching step of removing said X-ray absorber, said step of forming said transfer circuit pattern includes a second etching step of removing said X-ray absorber, and said first and second etching steps are performed under different conditions, respectively. writing a second mask pattern on said first mask layer while performing position detection of said first mask layer using said opening as an alignment mark; forming a second mask pattern layer by effecting development on said first mask layer; and forming a transfer circuit pattern by removing said X-ray absorber, using said second mask pattern layer as a mask. said step of writing said first mask pattern includes an exposure step using light, and said step of writing said second mask pattern includes a writing step using an electron beam. said step of forming said opening includes a first etching step of removing said X-ray absorber, said step of forming said transfer circuit pattern includes a second etching step of removing said X-ray absorber, and said first and second etching steps are performed under different conditions, respectively. 2. The X-ray mask according to claim 1, wherein said alignment mark is an opening formed in said X-ray absorber. 3. The X-ray mask according to claim 1, further comprising: 4. A method of manufacturing an X-ray mask, comprising the steps of: 5. The method of manufacturing the X-ray mask according to claim 4, further comprising the steps of: 6. The method of manufacturing the X-ray mask according to claim 5, wherein 7. The method of manufacturing the X-ray mask according to claim 5, wherein 8. The method of manufacturing the X-ray mask according to claim 5, wherein 9. The method of manufacturing the X-ray mask according to claim 4, further comprising: 10. The method of manufacturing the X-ray mask according to claim 9, wherein 11. The method of manufacturing the X-ray mask according to claim 9, wherein
053012119	claims	1. A method for coating the inside surface of a nuclear fuel assembly tubular component with a wear resistant metallic, ceramic or glass material, comprising: supporting the component tube in a fixture; supporting a source tube of said material coaxially within the component tube, thereby defining a cylindrical annular space between the tubes; evacuating the annular space and backfilling the annular space with an inert working gas to a pressure sufficient to sustain a plasma discharge; connecting a power supply to the component tube with a positive bias as an anode and to the source tube with a negative bias as a cathode, such that a plasma of the working gas is established in the annular space; establishing a circumferential magnetic field around the source tube to confine and shape the plasma; whereby the source tube is bombarded with ions from the plasma and said material is thereby sputtered from the source tube onto the inside surface of the component tube to form a coating thereon. the component tube has a length of at least about 12 ft and the source tube spans the length of the cladding tube; and said material is sputtered along at least about 10 ft of the component tube simultaneously. the source tube has a prescribed non-homogenous distribution of said material along its length, and said material is sputtered onto the component tube in a prescribed, non-homogeneous distribution along the length of the component tube. supporting the guide tube in a fixture; supporting a source tube of metallic material coaxially within the cladding tube, thereby defining a cylindrical annular space between the tubes; evacuating the annular space and backfilling the annular space with an inert working gas and a reactant gas to a pressure sufficient to sustain a plasma discharge; connecting a power supply to the guide tube with a positive bias as an anode and to the source tube with a negative bias as a cathode, such that a plasma of the working gas is established in the annular space; establishing a circumferential magnetic field around the source tube to confine and shape the plasma; whereby the source tube is bombarded with ions from the plasma and metallic material is thereby sputtered from the source tube so as to react with the reactant gas to form said metallic compound which is deposited as a coating on the inside surface of the guide tube. the guide tube has a length of at least about 12 ft and the source tube spans the length of the cladding tube; and the metallic material is sputtered along at least about 10 ft of the cladding tube simultaneously. the source tube has a prescribed non-homogenous distribution of metallic material along its length, and the metallic compound is sputtered simultaneously onto the cladding tube in a prescribed, non-homogeneous distribution along the length of the guide tube. the metallic compound is sputtered along less than one half the length of the guide tube. supporting the guide tube in a fixture; supporting a source tube of metallic material coaxially within the cladding tube, thereby defining a cylindrical annular space between the tubes; evacuating the annular space and backfilling the annular space with an inert working gas and a reactant gas to a pressure sufficient to sustain a plasma discharge; connecting a power supply to the guide tube with a positive bias as an anode and to the source tube with a negative bias as a cathode, such that a plasma of the working gas is established in the annular space; establishing a circumferential magnetic field around the source tube to confine and shape the plasma; whereby the source tube is bombarded with ions from the plasma and metallic material is thereby sputtered from the source tube so as to react with the reactant gas to form said ceramic compound which is deposited as a coating on the inside surface of the guide tube. the guide tube has a length of at least about 12 ft and the source tube spans the length of the cladding tube; and the metallic material is sputtered along at least about 10 ft of the cladding tube simultaneously. the source tube has a prescribed non-homogenous distribution of metallic material along its length, and the metallic is sputtered simultaneously onto the cladding tube in a prescribed, non-homogeneous distribution along the length of the guide tube. the metallic compound is sputtered along less than one half the length of the guide tube. 2. The method of claim 1, wherein 3. The method of claim 2, wherein 4. The method of claim 1, wherein the source tube material is selected from the group consisting of ceramics and glasses. 5. The method of 1, wherein the step of backfilling includes backfilling with a reactant gas which in the presence of the plasma and the sputtered material, chemically reacts with the sputtered material to form a compound material coating on the component tube. 6. The method of claim 5, wherein the compound material is an oxide, nitride or carbide. 7. The method of claim 5, wherein the reactant gas is nitrogen. 8. The method of claim 7, wherein the compound material is selected from the group consisting of ZrN, TiN, CrN, HfN, TiAlVN, and TaN. 9. The method of claim 5, wherein the reactant gas includes oxygen. 10. The method of claim 9, wherein the compound material is selected from the group consisting of Zr.sub.2 O.sub.3 and Al.sub.2 O.sub.3. 11. The method of claim 5, wherein the reactant gas includes carbon. 12. The method of claim 11, wherein the compound material is selected from the group consisting of TiCN, TiC, CrC, ZrC, and WC. 13. A method for coating the inside surface of a zircaloy control rod guide tube with a wear-resistant metallic compound material, comprising: 14. The method of claim 13, wherein 15. The method of claim 13, wherein 16. The method of claim 13, wherein 17. A method for coating the inside surface of a zircaloy control rod guide tube with a wear resistant ceramic compound, comprising: 18. The method of claim 17, wherein 19. The method of claim 17, wherein 20. The method of claim 17, wherein
	claims	1. A lithographic system, comprising:a support structure configured to support a patterning device, the patterning device configured to impart a beam of radiation with a pattern in its cross-section;a substrate holder configured to hold a substrate, the substrate comprising a plurality of target fields;a projection system configured to expose the patterned beam onto at least one of the target fields of the substrate, the at least one exposed target field being exposed in accordance with pre-specified exposure information; anda measurement station configured to measure an attribute of the at least one exposed target field, the at least one exposed target field being measured by the measurement station to assess deformation of the at least one exposed field induced by thermal effects of the exposure; anda controller configured to determine corrective information based on the measured field deformation and to adjust the pre-specified exposure information, based on the corrective information, to compensate for the thermally-induced field deformation,wherein the exposure information includes exposure energy information, or exposure time information, or both. 2. A lithographic system, comprising:a support structure configured to support a patterning device, the patterning device configured to impart a beam of radiation with a pattern in its cross-section;a substrate holder configured to hold a substrate, the substrate comprising a plurality of target fields;a projection system configured to expose the patterned beam onto at least one of the target fields of the substrate, the at least one exposed target field being exposed in accordance with pre-specified exposure information; anda measurement station configured to measure an attribute of the at least one exposed target field, the at least one exposed target field being measured by the measurement station to assess deformation of the at least one exposed field induced by thermal effects of the exposure; anda controller configured to determine corrective information based on the measured field deformation and to adjust the pre-specified exposure information, based on the corrective information, to compensate for the thermally-induced field deformation,wherein the controller comprises a global expansion model to predict thermally-induced field deformation, and is configured to modify the pre-specified exposure information, prior to exposure, based on the predicted thermally-induced field deformation information, andwherein the predicted thermally-induced field deformation information includes predicted deformation effects of selected points within each of the fields based on the global expansion model. 3. The lithographic system of claim 1, wherein the pre-specified exposure information adjustment includes adjustment of the pre-specified exposure field position information based on position offset information determined by the corrective information. 4. The lithographic system of claim 1, further comprising a model to predict thermally-induced field deformation information, and configured to modify the pre-specified exposure information, prior to exposure, based on the predicted thermally-induced field deformation information. 5. The lithographic system of claim 2, wherein the exposure information includes (i) exposure energy information, or (ii) exposure time information, or (iii) exposure field position information, or (iv) exposure field sequencing information, or (v) exposure field deformation information, or (vi) any combination from (i) to (v). 6. The lithographic system of claim 2, wherein the predictive model is based on: [ dx ] p = [ x r w · N i N tot · dx max ] ; and ⁢ [ dy ] p = [ y r w · N i N tot · dy max ] ; wheredxp: represents the predicted deformation along the x axis;dxmax: represents the predicted total deformation of the substrate in the x direction after the last target field has been exposed;x: represents the x coordinate of a point on the substrate;rw: represents the radius of the substrate;Ni: represents the current target field index number;Ntot: represents the total number of target fields;dymax: represents the predicted deformation along the y axis;dymax: represents the predicted total deformation of the substrate in the y direction after the last target field has been exposed; andy: represents the y coordinate of a point on the substrate. 7. The lithographic system of claim 6, wherein the pre-specified exposure information adjustment includes adjustment of the exposure field sequencing information based on the predicted thermally-induced field deformation information. 8. A lithographic system, comprising:a support structure configured to support a patterning device, the patterning device configured to impart a beam of radiation with a pattern in its cross-section;a substrate holder configured to hold a substrate, the substrate comprising a plurality of target fields;a projection system configured to expose the patterned beam onto at least one of the target fields of the substrate, the at least one exposed target field being exposed in accordance with pre-specified exposure information; anda measurement station configured to measure an attribute of the at least one exposed target field, the at least one exposed target field being measured by the measurement station to assess deformation of the at least one exposed field induced by thermal effects of the exposure; anda controller configured to determine corrective information based on the measured field deformation and to adjust the pre-specified exposure information, based on the corrective information, to compensate for the thermally-induced field deformation,wherein the controller comprises a model to predict thermally-induced field deformation, and is configured to modify the pre-specified exposure information, prior to exposure, based on the predicted thermally-induced field deformation information, andwherein the thermally-induced field deformation information includes predicted deformation effects of selected points within each of the fields of the substrate based on a time-decaying characteristic as energy is transported across the substrate. 9. The lithographic system of claim 8, wherein the predictive model is based on:dxp=ΣiTixDix; anddyp=ΣiTiyDiy; wheredxp: represents predicted deformation along the x axis;dyp: represents predicted deformation along the y axis; T i = ⅇ t - t i τ ⁢ : represents thermal effects of exposing one of the target fields Ci which will decay in time t as energy is transported across the substrate in either the x or y direction;τ: represents the time sensitivity constant which depends on the thermal properties of the lithographic exposure components;Di=ke−\| ri− r\|/χ: represents effects induced by a distance ri between the exposed target field Ci and a target field to be currently exposed in either the x or y direction;χ: represents the spatial thermal properties of the lithographic exposure components; andk: represents a proportionality constant which depends on thermal properties of the lithographic exposure components. 10. The lithographic system of claim 9, wherein the pre-specified exposure information adjustment includes adjustment of the exposure field sequencing information based on the predicted thermally-induced field deformation information. 11. A lithographic system, comprising:a support structure configured to support a patterning device, the patterning device configured to impart a beam of radiation with a pattern in its cross-section;a substrate holder configured to hold a substrate, the substrate comprising a plurality of target fields;a projection system configured to expose the patterned beam onto at least one of the target fields of the substrate, the at least one exposed target field being exposed in accordance with pre-specified exposure information; anda measurement station configured to measure an attribute of the at least one exposed target field, the at least one exposed target field being measured by the measurement station to assess deformation of the at least one exposed field induced by thermal effects of the exposure; anda controller configured to determine corrective information based on the measured field deformation and to adjust the pre-specified exposure information, based on the corrective information, to compensate for the thermally-induced field deformation,wherein the measurement station is configured to measure temperature variations on a surface of the substrate prior to exposure, and configured to generate a deformation map based on the measured substrate temperature variations. 12. The lithographic system of claim 11, wherein the controller is further configured to modify the pre-specified exposure information, prior to exposure, based on the deformation map. 13. The lithographic system of claim 11, wherein the temperature variation measurement includes thermographic imaging. 14. The lithographic system of claim 11, wherein the deformation map is characterized by: [ dx ] p = [ c ⁢ ⁢ x i r w ⁢ 1 N i ⁢ ∑ k ⁢ ( T k - T nom ) ] ; ⁢ [ dy ] p = [ c ⁢ ⁢ y i r w ⁢ 1 N i ⁢ ∑ k ⁢ ( T k - T nom ) ] ; ⁢ where ⁢ dxp: represents the predicted deformation along the x axis;xi: represents the x coordinate of field i;rw: represents the radius of the substrate;c: represents a proportionality constant (thermal expansion coefficient);Ni: represents the number of fields taken into account in the summation;k: sums over the relevant fields, along the connection line between the substrate center and field i;Tk: represents the measured temperature of field k;Tnom: represents the nominal temperature for which the lithographic system is set up;yi: represents the y coordinate of field i; anddyp: represents the predicted deformation along the y axis. 15. The lithographic system of claim 12, wherein the pre-specified exposure information adjustment includes adjustment of the modified pre-specified exposure information, after the exposure, based on deformation offset information determined by the corrective information.
	summary
	claims	1. A radiation-shielding container for storing a syringe, the radiation-shielding container comprising:a base assembly for housing a portion of the syringe, the base assembly including a body portion defining a chamber portion for receiving the syringe and including a base portion coupled to the body portion, the base portion including a radiation shield and a shell positioned proximate an outer surface of the radiation shield;a sleeve configured for receiving a portion of the syringe, the sleeve housed within the chamber portion and releasably securable to the base assembly; anda cap assembly for housing a portion of the syringe, the cap assembly defining a second chamber portion for receiving the syringe and including a radiation shield and a shell positioned proximate an outer surface of the radiation shield, wherein the cap assembly is securable to the base assembly. 2. The radiation-shielding container of claim 1 wherein the chamber portion of the body portion includes a first portion for receiving the sleeve and a second portion. 3. The radiation-shielding container of claim 2 wherein the second portion includes a reduced diameter relative to the first portion. 4. The radiation-shielding container of claim 2 wherein the body portion includes a first section defining the first portion and a second section defining the second portion, the second section received within the cavity of the base portion of the base assembly. 5. The radiation-shielding container of claim 4 wherein the base portion is coupled to the first section of the body portion. 6. The radiation-shielding container of claim 2, and further comprising a removable liner disposed in the second portion of the body portion, the removable liner attachable to a portion of the syringe. 7. The radiation-shielding container of claim 1, and further comprising:a cap-securing structure including at least one radially outwardly and circumferentially extending rib defined by the body portion; anda base-securing structure including at least one radially inwardly extending projection defined by the cap assembly for engagement with the cap-securing structure. 8. The radiation-shielding container of claim 1, and further comprising:a plurality of radially inwardly extending threads defined by the body portion; anda plurality of radially outwardly extending threads defined by the sleeve for engagement with the threads of the body portion. 9. The radiation-shielding container of claim 1 wherein the sleeve includes a generally cylindrical radiation shield defining a channel for receiving the syringe, and an outer sleeve positioned adjacent an outer surface of the radiation shield for securing the sleeve to the base assembly. 10. The radiation-shielding container of claim 9 wherein the outer sleeve is axially movable relative to the radiation shield of the sleeve between a first position and a second position, in which the outer sleeve substantially surrounds a portion of the syringe. 11. The radiation-shielding container of claim 10 wherein the sleeve includes a latching member for retaining the outer sleeve in the first position and the second position, the latching member actuatable to release the outer sleeve from the first position and the second position. 12. The radiation-shielding container of claim 1 wherein the cap assembly includes an inner layer positioned proximate an inner surface of the radiation shield. 13. The radiation-shielding container of claim 12 wherein the inner layer of the cap assembly defines a base-securing structure for securing the cap assembly to the base assembly. 14. A radiation-shielding container comprising:a syringe including a body, a plunger depending from one end of the body and axially movable relative to the body, and a needle extending from an opposite end of the body;a base assembly for housing a portion of the syringe, the base assembly including a body portion defining a chamber portion for receiving at least the body and the needle of syringe and including a base portion coupled to the body portion and defining a cavity for receiving a portion of the body portion, the base portion including a radiation shield and a shell positioned proximate an outer surface of the radiation shield;a sleeve configured for receiving at least the body of the syringe, the sleeve housed within the chamber portion and securable to the base assembly; anda cap assembly for housing a portion of the syringe, the cap assembly defining a second chamber portion for receiving at least the plunger of the syringe and including a radiation shield and a shell positioned proximate an outer surface of the radiation shield, wherein the cap assembly is securable to the base assembly. 15. The radiation-shielding container of claim 14 wherein the body portion includes a first section defining a first portion of the chamber portion and a second section defining a second portion of the chamber portion, the second section received within the cavity of the base portion of the base assembly. 16. The radiation-shielding container of claim 15, and further comprising a removable liner disposed in the second portion, the removable liner attachable to a portion of the syringe adjacent the needle. 17. The radiation-shielding container of claim 15 wherein the second portion includes a reduced diameter relative to the first portion. 18. The radiation-shielding container of claim 14 wherein the sleeve includes a retaining member for holding the syringe within the sleeve. 19. The radiation-shielding container of claim 14 wherein the sleeve includes a generally cylindrical radiation shield defining a channel for receiving the syringe, and an outer sleeve positioned adjacent an outer surface of the radiation shield for securing the sleeve to the base assembly. 20. The radiation-shielding container of claim 19 wherein the outer sleeve is axially movable relative to the radiation shield of the sleeve between a first position and a second position, in which the outer sleeve substantially surrounds the needle of the syringe. 21. The radiation-shielding container of claim 20 wherein the sleeve includes a latching member for retaining the outer sleeve in the first position and the second position, the latching member actuatable to release the outer sleeve from the first position and the second position. 22. A radiation-shielding container for storing a syringe, the radiation-shielding container comprising:a base assembly defining a cavity, the base assembly including a radiation shield and a shell positioned proximate an outer surface of the radiation shield;a body assembly including a first section defining a first chamber portion and a second section defining a second chamber portion for receiving a portion of the syringe, wherein the first section is coupled to the base assembly and the second section is received within the cavity;a sleeve being generally cylindrical and adapted and configured for receiving a portion of the syringe, the sleeve housed within the first chamber portion of the body assembly and releasably securable to the first section, the sleeve including a radiation shield; anda cap assembly defining a chamber portion for receiving a portion of the syringe and including a radiation shield and a shell positioned proximate an outside surface of the radiation shield, wherein the cap assembly is securable to the body assembly. 23. The radiation-shielding container of claim 22 wherein the second chamber portion has a reduced diameter relative to the first chamber portion. 24. The radiation-shielding container of claim 22 wherein the sleeve includes an outer sleeve positioned adjacent an outer surface of the radiation shield for securing the sleeve to the base assembly, the outer sleeve axially movable relative to the radiation shield between a first position and a second position, in which the outer sleeve substantially surrounds a portion of the syringe. 25. The radiation-shielding container of claim 24 wherein the sleeve includes a latching member for retaining the outer sleeve in the first position and the second position, the latching member actuatable to release the outer sleeve from the first position to the second position. 26. The radiation-shielding container of claim 22, and further comprising a removable liner disposed in the second chamber portion of the body assembly, the removable liner attachable to a portion of the syringe. 27. The radiation-shielding container of claim 22, and further comprising:a cap-securing structure including at least one radially outwardly and circumferentially extending rib defined by the body assembly; anda base-securing structure including at least one radially inwardly extending projection defined by the cap assembly for engagement with the cap-securing structure of the body assembly. 28. The radiation-shielding container of claim 22, and further comprising:a plurality of radially inwardly extending threads defined by the body assembly; anda plurality of radially outwardly extending threads defined by the sleeve for engagement with the threads of the body assembly.
	summary
	claims	1. An optical fiber penetration to be disposed in a sleeve provided through a partition wall that separates a first space and a second space, the optical fiber penetration comprising:a first optical fiber cable and a second optical fiber cable each having a thin tube formed of metal and an optical fiber strand inserted in the thin tube;a cylindrical body that is formed of metal and is disposed in an axial direction of the sleeve, an interior of which includes the first optical fiber cable on a side of the first space and the second optical fiber cable on a side of the second space;an internal connector configured to connect the first optical fiber cable with the second optical fiber cable in the interior of the cylindrical body; anda first lid and a second lid configured to close one end and the other end of the cylindrical body respectively,wherein the internal connector separates an interior of the thin tube of the first optical fiber cable and an interior of the thin tube of the second optical fiber cable, and electrically connects the optical fiber strand of the first optical fiber cable with the optical fiber strand of the second optical fiber cable. 2. The optical fiber penetration according to claim 1,wherein the internal connector includes:a socket to which an end of the thin tube of the first optical fiber cable is fixed, and which includes either a female contact or a male contact at a tip end of the optical fiber strand of the first optical fiber cable; anda plug to which an end of the thin tube of the second optical fiber cable is fixed, and which includes either a male contact or a female contact engaged with the contact in the socket, at a tip end of the optical fiber strand of the second optical fiber cable,wherein a periphery of the optical fiber strand of the second optical fiber cable is sealed with a resin to an interior of the plug, andwherein the plug is configured to be attached to the socket in such a manner that the female contact and the male contact are engaged with each other. 3. The optical fiber penetration according to claim 1,wherein the interior of the cylindrical body is filled with a resin. 4. The optical fiber penetration according to claim 3, further comprising:a partition plate that is provided in the interior of the cylindrical body to support the first optical fiber cable and the second optical fiber cable and also divide the interior of the cylindrical body into a plurality of spaces,wherein the resin fills at least one space including the internal connector among the spaces divided by the partition plate. 5. The optical fiber penetration according to claim 3,wherein the resin is a mixed resin in which a cyanate ester resin and an epoxy resin are mixed with each other. 6. The optical fiber penetration according to claim 2,wherein the interior of the cylindrical body is filled with a resin. 7. The optical fiber penetration according to claim 6, further comprising:a partition plate that is provided in the interior of the cylindrical body to support the first optical fiber cable and the second optical fiber cable and also divide the interior of the cylindrical body into a plurality of spaces,wherein the resin fills at least one space including the internal connector among the spaces divided by the partition plate. 8. The optical fiber penetration according to claim 6,wherein the resin is a mixed resin in which a cyanate ester resin and an epoxy resin are mixed with each other. 9. The optical fiber penetration according to claim 4,wherein the resin is a mixed resin in which a cyanate ester resin and an epoxy resin are mixed with each other. 10. The optical fiber penetration according to claim 7,wherein the resin is a mixed resin in which a cyanate ester resin and an epoxy resin are mixed with each other.
043137946	abstract	A self-actuating, self-locking flow cutoff valve particularly suited for use in a nuclear reactor of the type which utilizes a plurality of fluid support neutron absorber elements to provide for the safe shutdown of the reactor. The valve comprises a substantially vertical elongated housing and an aperture plate located in the housing for the flow of fluid therethrough, a substantially vertical elongated nozzle member located in the housing and affixed to the housing with an opening in the bottom for receiving fluid and apertures adjacent a top end for discharging fluid. The nozzle further includes two sealing means, one located above and the other below the apertures. Also located in the housing and having walls surrounding the nozzle is a flow cutoff sleeve having a fluid opening adjacent an upper end of the sleeve, the sleeve being moveable between an upper open position wherein the nozzle apertures are substantially unobstructed and a closed position wherein the sleeve and nozzle sealing surfaces are mated such that the flow of fluid through the apertures is obstructed. It is a particular feature of the present invention that the valve further includes a means for utilizing any increase in fluid pressure to maintain the cutoff sleeve in a closed position. It is another feature of the invention that there is provided a means for automatically closing the valve whenever the flow of fluid drops below a predetermined level.
	claims	1. A detector module for a radiation detector in a radiation imaging apparatus, the detector module comprising:a detecting element array comprising a plurality of detecting elements arranged in a matrix form in first and second directions orthogonal to each other, the detecting element array configured to allow radiation to penetrate through spaces defined between the detecting elements;an electronic circuit arranged on a radiation emission side of the detecting element array; anda radiation shielding body arranged on a radiation incident side of the detecting element array, the radiation shielding body comprising:a base material having radiation permeability and formed with a plurality of grooves extending in the first direction at respective positions corresponding to spaces between the detecting elements in the second direction; anda plurality of radiation shielding materials each inserted in a respective groove of the plurality of grooves. 2. The detector module according to claim 1, wherein the base material includes a carbon resin. 3. The detector module according to claim 1, wherein the base material is formed in a plate-like fashion. 4. The detector module according to claim 3, wherein the base material has a plate thickness greater than or equal to 0.2 mm and less than or equal to 1 mm. 5. The detector module according to claim 1, wherein the radiation shielding materials each contain one of tungsten and molybdenum. 6. The detector module according to claim 1, wherein the radiation shielding materials are each molded in a wire form, in a bar form, or by hardening powder. 7. The detector module according to claim 1, wherein the radiation shielding materials each have a width in the second direction that is equivalent to a length that is from one to three times a width of each of the spaces. 8. The detector module according to claim 1, wherein the detecting elements each comprise a scintillator and a photoelectric conversion element. 9. The detector module according to claim 1, wherein the detecting element array comprises a light-reflecting member positioned in the spaces. 10. The detector module according to claim 1, wherein the electronic circuit comprises a circuit configured to process signals outputted from the detecting elements. 11. The detector module according to claim 1, wherein the electronic circuit comprises an integrated circuit. 12. A radiation detecting device comprising:a radiation detector in which a plurality of detector modules according to claim 1 are arranged in the first direction; anda plurality of collimator plates arranged on a radiation incident side of the radiation detector and each extending in the second direction at respective positions corresponding to the spaces defined between the detecting elements in the first direction. 13. A radiation detecting device comprising:a radiation detector in which a plurality of detector modules according to claim 2 are arranged in the first direction; anda plurality of collimator plates arranged on a radiation incident side of the radiation detector and each extending in the second direction at respective positions corresponding to the spaces defined between the detecting elements in the first direction. 14. A radiation detecting device comprising:a radiation detector in which a plurality of detector modules according to claim 11 are arranged in the first direction; anda plurality of collimator plates arranged on a radiation incident side of the radiation detector and each extending in the second direction at respective positions corresponding to the spaces defined between the detecting elements in the first direction. 15. A radiation imaging apparatus comprising a radiation detecting device according to claim 12. 16. A radiation imaging apparatus comprising a radiation detecting device according to claim 13. 17. A radiation imaging apparatus comprising a radiation detecting device according to claim 14. 18. The radiation imaging apparatus according to claim 15, wherein the radiation imaging apparatus is configured to perform radiation tomographic imaging. 19. The radiation imaging apparatus according to claim 16, wherein the radiation imaging apparatus is configured to perform radiation tomographic imaging. 20. The radiation imaging apparatus according to claim 17, wherein the radiation imaging apparatus is configured to perform radiation tomographic imaging.
	claims	1. A radiation image detecting device for carrying out imaging by using a scattered radiation removing grid having radiation absorbing portions for absorbing radiation and radiation transmitting portions for transmitting said radiation alternately and periodically arranged in a first direction, said radiation image detecting device comprising:a detection panel having an imaging surface provided with a plurality of pixels for converting said radiation into an electric signal, for detecting a radiographic image of an object;a plurality of dose detection sensors provided for performing exposure control of said radiographic image, said plurality of dose detection sensors being disposed in said imaging surface periodically with leaving space in said first direction, for detecting a dose of said radiation passed through said object and outputting a signal in accordance with said dose; andan arrangement period of said radiation absorbing portions being different from an arrangement period of said plurality of dose detection sensors in said first direction in said imaging surface,wherein an arrangement period of said dose detection sensors in a second direction orthogonal to said first direction is also different from said arrangement period of said radiation absorbing portions. 2. The radiation image detecting device according to claim 1, wherein said arrangement period of said dose detection sensors is not an integral multiple of said arrangement period of said radiation absorbing portions. 3. The radiation image detecting device according to claim 1, wherein each of said arrangement period of said dose detection sensors and said arrangement period of said radiation absorbing portions has a length in unit of the number of said pixels, and said arrangement periods are co-prime numbers. 4. The radiation image detecting device according to claim 1, wherein said arrangement period of said dose detection sensors in said second direction is the same as said arrangement period of said dose detection sensors in said first direction. 5. The radiation image detecting device according to claim 1, wherein a minimum size of said dose detection sensor is the same as the size of said pixel in said imaging surface. 6. The radiation image detecting device according to claim 1, wherein said dose detection sensors are detection pixels of which some of said pixels are utilized. 7. The radiation image detecting device according to claim 1, whereinsaid radiation detection sensors are detection pixels as which some of said pixels are utilized; andin a case where a plurality of said detection pixels are disposed with being shifted by one or more rows and one or more columns in each of a row direction corresponding to said first direction and a column direction corresponding to said second direction, an arrangement period in said first direction is a length in said row direction, and an arrangement period in said second direction is a length in said column direction. 8. The radiation image detecting device according to claim 6, wherein said dose detection sensor is a detection pixel group composed of a plurality of said detection pixels adjoining each other. 9. The radiation image detecting device according to claim 8, wherein said arrangement period of said dose detection sensors corresponds to an arrangement period of a plurality of said detection pixel groups arranged periodically with leaving space. 10. The radiation image detecting device according to claim 1, whereinsaid dose detection sensor outputs said signal in accordance with said dose per unit of time; andsaid radiation image detecting device further includes an automatic exposure control section for integrating an output value of said dose detection sensor, and comparing an integral value with an emission stop threshold value set in advance, and stopping emission of said radiation from a radiation source upon said integral value reaching said emission stop threshold value. 11. The radiation image detecting device according to claim 10, wherein said automatic exposure control section calculates an average of said output values of a plurality of said dose detection sensors, and obtains said integral value by integrating said calculated average. 12. The radiation image detecting device according to claim 1, wherein said scatter radiation removing grid is detachably attached. 13. A radiation imaging system for carrying out imaging by using a scattered radiation removing grid having radiation absorbing portions for absorbing radiation and radiation transmitting portions for transmitting said radiation alternately and periodically arranged in a first direction, said radiation imaging system comprising:(A) a radiation generating device including a radiation source for emitting radiation; and(B) a radiation image detecting device for detecting a radiographic image, including:a detection panel having an imaging surface provided with a plurality of pixels for converting said radiation emitted from said radiation source into an electric signal, for detecting said radiographic image of an object;a plurality of dose detection sensors provided for performing exposure control of said radiographic image, said plurality of dose detection sensors being disposed in said imaging surface periodically with leaving space in said first direction, for detecting a dose of said radiation passed through said object and outputting a signal in accordance with said dose; andan arrangement period of said radiation absorbing portions being different from an arrangement period of said plurality of dose detection sensors in said first direction in said imaging surface,wherein an arrangement period of said dose detection sensors in a second direction orthogonal to said first direction is also different from said arrangement period of said radiation absorbing portions.
	summary
	claims	1. A sensor assembly for measuring the relative position of a control rod connected to a lead screw within a nuclear reactor from within a metallic probe tube housing the sensor assembly, the sensor assembly including:a primary electromagnetic coil arranged to generate a time varying magnetic field; anda secondary electromagnetic coil coaxial with the primary electromagnetic coil, the primary and secondary electromagnetic coils being wound around a core body coaxially, the secondary electromagnetic coil being arrangedto detect the time varying magnetic field as affected, directly or indirectly, by the lead screw, andto output, on the basis of the detected time varying magnetic field, a signal indicative of the relative location of the lead screw;whereinthe core body being formed of a material having the same conductivity and/or magnetic permeability as the lead screw to which the control rod is connected in the nuclear reactor. 2. A sensor assembly according to claim 1 including a plurality of primary electromagnetic coils. 3. A sensor assembly according to claim 1 including a plurality of primary and secondary coils, wherein the primary coils are mutually arranged in electrical series; and/or wherein the secondary coils are separately mutually arranged in electrical series. 4. A sensor assembly according to claim 1 wherein the primary and/or secondary coils are formed of an alloy comprising 86% copper, 12% Manganese and 2% Nickel. 5. A sensor assembly according to claim 1 wherein the core body is formed of the same material as the lead screw. 6. A sensor assembly according to claim 1 including a plurality of secondary electromagnetic coils. 7. A sensor assembly according to claim 6 wherein the plurality of primary and secondary coils are arranged in a mutually alternating sequence of primary and secondary coils. 8. A method of optimising the output of a sensor assembly for measuring the relative position of a control rod connected to a lead screw within a nuclear reactor from within a metallic probe tube housing the sensor assembly, the sensor assembly including a primary electromagnetic coil arranged to generate a time varying magnetic field and a secondary electromagnetic coil coaxial with the primary electromagnetic coil, the primary and secondary electromagnetic coils being wound around a core body coaxially, the secondary electromagnetic coil being arranged to detect the time varying magnetic field as affected, directly or indirectly, by the lead screw, and to output, on the basis of the detected time varying magnetic field, a signal indicative of the relative location of the lead screw, the core body being formed of a material having the same conductivity and/or magnetic permeability as the lead screw to which the control rod is connected in the nuclear reactor, the method including the steps of:supplying the primary coil with an alternating current to result in the generated time varying magnetic field;locating the lead screw in a first position and recording the signal output by the secondary electromagnetic coil for a range of respective frequencies of the supplied alternating current;locating the lead screw in a second position and recording the signal output by the secondary electromagnetic coil for the range of respective frequencies of the supplied alternating current;calculating, for each of the respective frequencies, a value for the span-to-offset ratio of the measured signals on the basis of the respective signals measured for the lead screw in the first and second positions; anddetermining the frequency of the supplied alternating current which provides the maximum span-to-offset ratio on the basis of the calculations. 9. A method according to claim 8, whereinwhen the lead screw is in the first position, the output from the secondary coil is a maximum; and/orwhen the lead screw is in the second position, the output from the secondary coil is a minimum. 10. A method according to claim 8, whereinthe calculation step includes, for each respective frequency:calculating the difference between the amplitudes of the signals measured for the lead screw in the first and second positions; anddividing the difference by the amplitude of the signal measured for the lead screw in the second position. 11. A combination of a lead screw connected to a control rod within a nuclear reactor and a sensor assembly for measuring the relative position of the control rod connected to the lead screw within the nuclear reactor from within a metallic probe tube housing the sensor assembly, the combination including:a lead screw connected to a control rod within a nuclear reactor; anda sensor assembly including:a primary electromagnetic coil arranged to generate a time varying magnetic field; anda secondary electromagnetic coil coaxial with the primary electromagnetic coil, the primary and secondary electromagnetic coils being wound around a core body coaxially, the secondary electromagnetic coil being arrangedto detect the time varying magnetic field as affected, directly or indirectly, by the lead screw, andto output, on the basis of the detected time varying magnetic field, a signal indicative of the relative location of the lead screw;whereinthe core body being formed of a material having the same conductivity and/or magnetic permeability as the lead screw to which the control rod is connected in the nuclear reactor.
	abstract	A pump liner is used to direct a laminar flow of purge gas across a workpiece to remove contaminants or species outgassed or otherwise produced by the workpiece during processing. The pump liner can take the form of a ring having a plurality of injection ports, such as slits of a variety of shapes and/or sizes, opposite a plurality of receiving ports in order to provide the laminar flow. The flow of purge gas is sufficient to carry a contaminant or outgassed species from the processing chamber in order to prevent the collection of the contaminants on components of the chamber. The pump liner can be heated, via conduction and irradiation from a radiation source, for example, in order to prevent the condensation of species on the liner. The pump liner also can be anodized or otherwise processed in order to increase the emissivity of the liner.
	abstract	A nuclear fuel pellet with a porous substrate, such as a carbon or tungsten aerogel, on which at least one layer of a fuel containing material is deposited via atomic layer deposition, and wherein the layer deposition is controlled to prevent agglomeration of defects. Further, a method of fabricating a nuclear fuel pellet, wherein the method features the steps of selecting a porous substrate, depositing at least one layer of a fuel containing material, and terminating the deposition when the desired porosity is achieved. Also provided is a nuclear reactor fuel cladding made of a porous substrate, such as silicon carbide aerogel or silicon carbide cloth, upon which layers of silicon carbide are deposited.
	description	The invention is described below in the context of representative embodiments. However, it will be understood that the invention is not limited to those embodiments. Also, the invention is described in the context of using an electron beam as an exemplary charged particle beam. However, it will be understood that the general principles set forth herein are applicable with equal facility to other types of charged particle beams, such as an ion beam. Reference is made first to FIG. 3, depicting certain general aspects of an electron-beam microlithography apparatus used for step-and-repeat projection-transfer of a pattern from a reticle to a suitable substrate (e.g., semiconductor wafer). FIG. 3 especially shows certain details of the xe2x80x9celectron-optical systemxe2x80x9d of the apparatus, including the focusing system and a system for controlling operation of the electron-optical system. An electron gun 1 is situated at the extreme upstream end of the electron-optical system. The electron gun 1 emits an electron beam that propagates downstream of the electron gun generally in the direction of an xe2x80x9coptical axisxe2x80x9d AX (i.e., Z-direction). The electron beam propagating from the electron gun 1 to a reticle 10 is termed an xe2x80x9cillumination beam,xe2x80x9d and the portion of the electron-optical system arranged along the axis AX between the electron gun 1 and the reticle 10 is termed the xe2x80x9cillumination-optical system.xe2x80x9d The illumination-optical system comprises two condenser lenses 2, 3 that converge the illumination beam at a crossover C.O.1 situated at a blanking aperture 7. A xe2x80x9cbeam-shapingxe2x80x9d aperture 4 (generally rectangular in profile) is situated downstream of the second condenser lens 3. The beam-shaping aperture 4 transmits only a portion of the illumination beam sufficient to illuminate a single subfield (exposure unit) of the pattern defined on the reticle 10. For example, in this embodiment, the beam-shaping aperture 4 trims the illumination beam to a square transverse profile with dimensions slightly greater than 1 mm per side to illuminate a (1 mm)-square subfield on the reticle 10. An image of the beam-shaping aperture 4 is formed by an illumination lens 9 on the surface of the reticle 10. A blanking deflector 5 is situated either downstream or upstream of the beam-shaping aperture 4. The blanking deflector 5 deflects the illumination beam as required to be incident on a non-transmissive portion of the blanking aperture 7. Whenever the illumination beam is xe2x80x9cblankedxe2x80x9d in this manner, it does not pass through the blanking aperture 7 and thus is not incident on the reticle 10. A subfield-selection deflector 8 is situated downstream of the blanking aperture 7. The subfield-selection deflector 8 mainly scans the illumination beam left and right in FIG. 3 (i.e., the X-direction) so as to illuminate the subfields on the reticle 10 in a sequential manner. The magnitude of lateral beam deflection imparted by the subfield-selection deflector 8 is within the optical field of the illumination-optical system. Another component of the illumination-optical system is the illumination lens 9 situated downstream of the deflector 8. The illumination lens 9 collimates the illumination beam before the beam is incident on the reticle 10. The illumination lens 9 also forms the image of the beam-shaping aperture 4 on the reticle 10. It will be understood from the foregoing that the optical components of the illumination-optical system guide and shape the illumination beam as the beam propagates from the electron gun 1 to the reticle 10. The reticle 10 is depicted in FIG. 3 as a single subfield located on the optical axis AX. However, it will be understood that an actual reticle contains a plurality (typically many thousands) of subfields extending in the X-Y plane perpendicular to the optical axis AX. The reticle 10 typically defines the entire pattern for a layer of a chip (die) to be formed on a substrate (xe2x80x9cwaferxe2x80x9d) 15. As noted above, the subfield-selection deflector 8 deflects the illumination beam laterally within the optical field of the illumination-optical system. To allow exposure of subfields located outside the optical field, the reticle 10 is mounted to a reticle stage 11 that is movable in the X- and Y-directions. This movement is imparted by respective linear motors denoted generally by the reference numeral 11b. Situated below the reticle 10 (between the reticle 10 and the substrate 15) are various components of an xe2x80x9cimaging-optical system,xe2x80x9d described below. As particles of the illumination beam are transmitted through an illuminated subfield on the reticle 10, they become a xe2x80x9cpatterned beamxe2x80x9d (also termed an xe2x80x9cimaging beamxe2x80x9d) that passes through the imaging-optical system to the wafer 15. The patterned beam carries an image of the illuminated subfield. The imaging-optical system includes a first (or reticle-side) electromagnetic projection lens 12 and a second (or wafer-side) electromagnetic projection lens 14. As the patterned beam passes through the projection lenses 12, 14, the image carried by the beam is xe2x80x9cdemagnified,xe2x80x9d projected onto, and formed at a predetermined location on the wafer 15. To be imprintable with the image, the upstream-facing surface of the wafer 15 is coated with a suitable resist. As the patterned beam is incident on region of the wafer surface, corresponding to the particular subfield being illuminated, a demagnified latent image of the subfield is formed at the region, thereby completing xe2x80x9ctransferxe2x80x9d of the image of the subfield. By xe2x80x9cdemagnifiedxe2x80x9d is meant that the image as formed on the wafer 15 is smaller (typically by a xe2x80x9cdemagnification ratioxe2x80x9d factor 1/X, wherein X usually is 2 to 10) than the corresponding subfield on the reticle 10. As the patterned beam propagates through the imaging-optical system, a crossover C.O.2 is formed at a point on the axis AX at which the axial distance between the reticle 10 and the wafer 15 is divided according to the demagnification ratio. A xe2x80x9ccontrast aperturexe2x80x9d 18 normally is provided at the crossover C.O.2. The contrast aperture 18 blocks scattered particles of the patterned beam, thereby preventing the scattered particles from propagating to the wafer 15 on which the particles otherwise would expose the resist and cause blur of the images formed on the wafer. The wafer 15 is mounted on an electrostatic wafer chuck 16 situated on a wafer stage 17 that is movable in the X- and Y-direction. This movement is imparted by respective linear motors denoted generally by the reference numeral 17b. During exposure, the reticle stage 11 and wafer stage 17 are scanned synchronously in mutually opposite directions to allow a plurality of aligned subfields in a chip pattern to be exposed sequentially. Furthermore, both stages 11, 17 are provided with respective position-measuring systems comprising laser interferometers for measuring the respective stage positions with extremely high accuracy. Hence, the position of the patterned beam as incident on the wafer 15 can be controlled with high accuracy. Energization of each of the lenses 2, 3, 9, 12, 14 and of each of the deflectors 5, 8 is controlled by a controller 21 via individual coil power supplies 2a, 3a, 9a, 12a, 14a, and 5a, 8a, respectively. Similarly, the linear motors 11b, 17b of the reticle stage 11 and wafer stage 17, respectively, are controlled by the controller 21 via respective stage drivers 11a, 17a. Further similarly, the wafer chuck 16 is operated in a controllable manner by the controller 21 via a chuck driver 16a. Hence, by accurate stage positioning and operation of the illumination- and imaging-optical systems, the demagnified images of the reticle subfields are formed and xe2x80x9cstitched togetherxe2x80x9d accurately on the wafer 15, thereby achieving transfer of the entire chip pattern onto the wafer 15. As well understood in the art, the electron gun 1, illumination-optical system, imaging-optical system, the reticle stage 11 and the wafer stage 17 are situated inside a vacuum chamber (not shown) that is evacuated by a vacuum pump (not shown). The vacuum chamber and electron-optical components enclosed therein is referred to as the xe2x80x9ccolumn.xe2x80x9d Details of the wafer-side electromagnetic projection lens 14 and the reticle-side electromagnetic projection lens 12 are shown in FIGS. 1 and 2, respectively. FIG. 1 is an enlarged elevational section of the lower right portion of the wafer-side projection lens 14 and its vicinity. The wafer-side projection lens 14 comprises a magnetic pole 19 that is rotationally symmetrical about the axis 27 and has a xe2x80x9cCxe2x80x9d radial section opening toward the axis 27. Conductive windings 20 are configured as a coil situated inside the magnetic pole 19. The magnetic pole 19 is made of a ferromagnetic material such as Permalloy or soft iron. The coil windings 20 are energized with an electrical current to cause the magnetic pole 19 to produce a magnetic field. The magnetic pole 19 also serves as a shield that blocks inward incursion of external magnetic fields. Along the inside diameter of the magnetic pole 19 is a ferrite stack 22 comprising alternating rings of an insulator material 22a and a ferrite material 22b stacked vertically in the figure (i.e., in the direction of the optical axis 27). The ferrite stack 22 is a magnetic shield that blocks outward escape of the deflection magnetic fields produced by deflection coils 23-25 (described later). Situated radially inward of the ferrite stack 22 are the deflection coils 23-25, which function to correct aberrations and the like of the wafer-side projection lens 14. The deflection coils 23-25 are stacked in the vertical (axial) direction in the figure. The respective downstream-facing surfaces of the wafer-side projection lens 14, of the ferrite stack 22, and of the deflection coil 25 are all xe2x80x9ccoveredxe2x80x9d by a rotationally symmetrical xe2x80x9clowerxe2x80x9d first vacuum wall 26. The lower first vacuum wall 26 desirably is made of an insulator material such as ceramic or plastic. A rotationally symmetrical xe2x80x9clowerxe2x80x9d second vacuum wall 28 extends in an upstream direction from and is attached to the xe2x80x9cupperxe2x80x9d surface of the peripheral edge of the lower first vacuum wall 26. The outside of the wafer-side projection lens 14 substantially is xe2x80x9ccoveredxe2x80x9d by the lower second vacuum wall 28, which desirably is made of soft iron or a material such as Permalloy or Permendur. The downstream end of the lower second vacuum wall 28 extends radially toward the axis 27 and defines a gland (groove) 28aconfigured to hold an elastomeric O-ring 29 or analogous sealing member. The O-ring 29 forms a circumferential seal where the lower first vacuum wall 26 contacts the lower second vacuum wall 28. A liner tube 30 extends in the optical-axis direction (vertical direction in the figure) and is attached circumferentially to the lower first vacuum wall 26 at an inside edge 26b of the lower first vacuum wall 26. The inside edge 26b defines a ring-shaped gland (groove) 26a configured to hold an elastomeric O-ring 31 or analogous sealing member. Thus, the O-ring 31 forms a circumferential seal between the inside edge 26b of the lower first vacuum wall 26 and the downstream end of the liner tube 30. A wafer Z-position sensor (not shown, but known in the art) is disposed to direct a light beam (and receive a reflected light beam) at a shallow angle (grazing-incidence angle) upward from the surface of the wafer 15. The incident and reflected light beams propagate within defined respective zones 32. The reflected beam is detected and processed in a manner yielding information concerning the axial height position of the wafer 15. As a result of the configuration described above, the space located radially inward from the wafer-side projection lens 14 is shielded magnetically by the magnetic pole 19 from magnetic fields generated by electrical current flowing in conductors located outside the column, by movements of conductive bodies within or outside the column, and by movements of the linear motor 17b actuating the wafer stage 17. These various magnetic fields are termed simply herein xe2x80x9cstray magnetic fields.xe2x80x9d The area situated in a gap between the downstream-facing surface of the wafer-side projection lens 14 and the wafer 15 is affected easily by stray magnetic fields (generated by, e.g., the linear motor 17b) because this area is outside the effective electromagnetic lens-effect range of the wafer-side projection lens 14. If the patterned beam propagating through this area were to be affected adversely by a stray magnetic field, then the irradiation position of the patterned beam on the upstream-facing (sensitive) surface of the wafer 15 would be affected correspondingly, leading to undesired variations in exposure position on the wafer surface. The effects of stray magnetic fields can be suppressed by narrowing this gap, but some gap must be present to provide the zone 32 in which the Z-sensor light beam can propagate without obstruction. The magnitude of variation in position of the patterned beam on the sensitive surface of the wafer 15 can be expressed as a product of the magnitude of the stray magnetic field and the axial distance from the sensitive surface of the wafer 15 to the location of the stray magnetic field. I.e., the magnitude of variation in beam position is proportional to this axial distance. Hence, if a strong stray magnetic field were present directly on the sensitive surface of the wafer 15, then the axial distance would be zero and no beam-position variation would be exhibited. But, the effect of a stray magnetic field is significant upstream from the sensitive surface. Therefore, it is important to shield against stray magnetic fields in the region from the xe2x80x9clowerxe2x80x9d (downstream-facing) surface of the wafer-side projection lens 14 to near the sensitive surface of the wafer 15. In view of the above, and according to this embodiment, a first magnetic shield 33 is attached to the xe2x80x9clowerxe2x80x9d (downstream-facing) surface of the lower first vacuum wall 26. As discussed above, the magnitude of variation of beam position caused by a stray magnetic field is proportional to the axial distance from the sensitive surface of the wafer 15 to the location where the stray magnetic field is generated. Therefore, a shield against the stray magnetic field must function effectively from the location of the shield upstream wafer 15 to a location adjacent the sensitive surface of the wafer 15, without obstructing the zone 32 for the light beam for the Z-position sensor. Hence, in this embodiment, the first magnetic shield 33 is disposed so that a xe2x80x9clowerxe2x80x9d surface 33e of the first magnetic shield 33 is adjacent as close as possible to the zone 32 without obstructing the zone 32. For example, the first magnetic shield 33 is close to the zone 32 at two places in a radial direction, while maintaining a slight clearance between the first magnetic shield 33 and the zone 32. In this embodiment, the first magnetic shield 33 is a three-layer clad structure in which a copper layer 33h is sandwiched between two ferromagnetic (e.g., Supermalloy) layers 33f, 33g that are each 0.5 xcexcm thick. Structuring the first magnetic shield 33 in this way as a multilayer structure that includes at least two ferromagnetic body layers 33f, 33g having a nonmagnetic body layer 33h therebetween is equivalent to using a thick ferromagnetic body, and provides a strong shielding effect. In this embodiment, the first magnetic shield 33 is rotationally symmetrical about the optical axis 27. In this regard, by way of example, the first magnetic shield 33 in this embodiment includes an upturned-lip portion 33a (having an L-shaped elevational section) and a shallow xe2x80x9cconicalxe2x80x9d part 33b connected to the L-shaped part 33a. The shallow conical part 33b actually has a 3-dimensional profile of a truncated cone, and has an xe2x80x9cinnerxe2x80x9d (or xe2x80x9cfirst axis-facingxe2x80x9d as referred to in the claims) surface 33c that is conical. By adjusting the magnetic-field parameters of the wafer-side projection lens 14 to integrate the magnetic field produced by the lens with the magnetic field produced by the first magnetic shield 33, aberrations are canceled that otherwise would occur if the first magnetic shield 33 were not axially symmetrical about the optical axis 27. Furthermore, third-order and fifth-order aberrations, for example, that ordinarily would not be cancelled even with the inner surface 33c of the first magnetic shield 33 being conical nevertheless can be cancelled by suitably adjusting the energization parameters of the wafer-side projection lens 14. Energization parameters include respective electrical energizations of the deflection coils 23-25. A xe2x80x9cshielding ratioxe2x80x9d S (a measure of shield xe2x80x9cstrengthxe2x80x9d) of a cylindrical magnetic shield, made of a ferromagnetic material, against a stray magnetic field is defined by the following Equation (1): S=xcexct/2Rxe2x80x83xe2x80x83(1) wherein t is the thickness of the magnetic shield, R is the inside diameter of the magnetic shield, and xcexc is the permeability of the magnetic shield. Equation (1) indicates that, for a cylindrical magnetic shield, the shielding ratio S can be increased by decreasing the inside diameter R of the magnetic shield or by increasing either the thickness t or the permeability xcexc of the shield. But, as the inside diameter of the magnetic shield is reduced, increased eddy currents are created in the magnetic shield in response to the magnetic fields generated by deflector(s) (e.g., deflector coils 23-25) used to correct electromagnetic lens aberrations, etc. The eddy currents produce corresponding delays in the time constant of the deflector(s). Therefore, in this embodiment, the inside diameter (measured at the edge 33d) of the first magnetic shield 33 is slightly greater than the inside diameter of the ferrite stack 22. With such a configuration, the first magnetic shield 33 efficiently shields against stray magnetic fields without causing a delay in the time constant of the deflection coils 23-25. The configuration of the first magnetic shield 33 described above also allows stray magnetic fields created between the wafer-side projection lens 14 and the wafer 15 to flow smoothly from the first magnetic shield 33 to the lower second vacuum wall 28. This effect provides further shielding against stray magnetic fields. As shown in FIG. 3, the reticle-side projection lens 12 is disposed upstream of the wafer-side projection lens 14. FIG. 2 is an enlarged elevational section of the xe2x80x9cupperxe2x80x9d right portion of the reticle-side electromagnetic projection lens 12 and its vicinity. The reticle-side projection lens 12 comprises a magnetic pole 6 that is rotationally symmetrical about the axis 27 and has a xe2x80x9cCxe2x80x9d radial section opening toward the axis 27. The magnetic pole 6 is made of a ferromagnetic material such as Permalloy or soft iron. Conductive windings 13 are configured as a coil situated inside the magnetic pole 6. The magnetic pole 6 also serves as a magnetic shield that blocks inward incursion of external magnetic fields toward the axis. Inward of the reticle-side projection lens 12 is situated a first ferrite stack 34 made of alternating rings of an insulator material 34a and of a ferrite material 34b. The rings are stacked in the xe2x80x9cverticalxe2x80x9d (axial) direction. The first ferrite stack 34 functions as a shield that blocks the deflection magnetic field produced by a first deflector coil 35 (described later) from leaking outward. The first deflector coil 35 is situated radially inwardly of the first ferrite stack 34 and serves to correct aberrations, etc., in the reticle-side projection lens 12. A second ferrite stack 36 is disposed upstream of the reticle-side projection lens 12, and comprises alternating rings made of an insulator material 36a and rings made of a ferrite material 36b stacked in the xe2x80x9cverticalxe2x80x9d (axial) direction. Inward of the second ferrite stack 36 is a second deflector coil 37 that also serves to correct aberrations, etc., in the reticle-side projection lens 12. The upstream-facing surface of the second ferrite stack 36 and of the second deflection coil 37 are xe2x80x9ccoveredxe2x80x9d by an xe2x80x9cupperxe2x80x9d first vacuum wall 38 made of a material that is non-magnetic and non-metallic. A rotationally symmetrical xe2x80x9cupperxe2x80x9d second vacuum wall 39, extending xe2x80x9cdownwardxe2x80x9d in the figure (i.e., in the axial direction), is attached at the peripheral lower edge 38c of the upper first vacuum wall 38. Thus, the upper second vacuum wall 39 effectively extends over and xe2x80x9ccoversxe2x80x9d the outside diameter of the reticle-side projection lens 12. The upper second vacuum wall 39 is made of a ferromagnetic material. The upstream-facing edge of the upper second vacuum wall 39 defines a ring-shaped gland (groove) 39a extending downward in the figure. The gland 39a is configured to receive an elastomeric O-ring 40 or analogous sealing member. The O-ring 40 forms a seal at the area of contact of the peripheral lower edge 38c of the upper first vacuum wall 38 with the upper second vacuum wall 39. An upstream end of the tube-shaped liner tube 30 (that extends cylindrically in the optical-axis direction, or vertical direction in the figure) is attached circumferentially to the upper first vacuum wall 38 at an inner edge 38b of the upper first vacuum wall 38. Thus, the upstream end of the liner tube 30 is attached to the upper first vacuum wall 38 of the reticle-side projection lens 12, and the downstream end of the liner tube 30 is attached to the lower first vacuum wall 26 of the wafer-side projection lens 14. On the upstream end of the liner tube 30, the inner edge 38b of the upper first vacuum wall 38 defines a ring-shaped gland (groove) 38a in which is placed an elastomeric O-ring 41 or analogous sealing member. The O-ring 41 forms a seal between the inner edge 38b of the upper first vacuum wall 38 and the outer diameter of the upstream end of the liner tube 30. The liner tube 30 desirably is configured as a cylinder having an axis that is coincident with the optical axis 27. Midway in an axial direction from the projection lens 12 to the projection lens 14, the liner tube defines a circular ledge 30a where the inside diameter of the liner tube 30 abruptly narrows. The ledge 30a supports the contrast aperture 18. A reticle Z-position sensor (not shown, but known in the art) is disposed to direct a light beam (and receive a reflected light beam) at a shallow angle (grazing-incidence angle) downward (in the figure) from the surface of the reticle 10. The incident and reflected light beams propagate within a defined zone 42. The reflected beam is detected and processed in a manner yielding information concerning the axial height position of the reticle 10. Hence, the reticle-side Z-position sensor is a so-called xe2x80x9cgrazing-incidencexe2x80x9d-type sensor. The space situated radially inwardly from the reticle-side projection lens 12 is blocked magnetically by the magnetic pole 6 against external stray magnetic fields. Notwithstanding this blocking, the area between the reticle 10 and the upstream-facing surface of the reticle-side projection lens 12 is affected easily by stray magnetic fields (such as from the linear motors 11b of the reticle stage 11) because this area is outside the effective electromagnetic lens-effect range of the reticle-side projection lens 12. If the patterned beam were to be affected by a stray magnetic field, then the beam position on the sensitive surface of the wafer 15 would exhibit unwanted variation. Effects of stray magnetic fields can be suppressed by narrowing the gap between the reticle and the projection lens 12. (However, this approach has limitations because the gap still must allow for the zone 42 used by the light beam of the Z-position sensor.) The magnitude of variation of the beam position is a function of the product of the field strength of the stray magnetic field and the axial distance from the downstream-facing surface of the reticle 10 to the location where the stray magnetic field is created. That is, the magnitude of the variation in beam position is proportional to that distance. Similar to the wafer-side projection lens 14, it is desirable to block incursion of stray magnetic fields from a region extending from the downstream-facing surface of the reticle 10 to the upstream-facing surface of the reticle-side projection lens 12. To such end, the FIG. 2 embodiment includes a second magnetic shield 43 fastened to the upper second vacuum wall 39. The variation of beam position also is proportional to the axial distance from the downstream-facing surface of the reticle 10 to the location where a stray magnetic field is created. Hence, shielding against stray magnetic fields is desirable in this region without interfering with the zone 42 in which the beam of the Z-position sensor propagates. To such end, in this embodiment, the second magnetic shield 43 is disposed so that its upstream-facing surface is adjacent the zone 42 without actually being in the zone. I.e., the upstream-facing surface of the second magnetic shield 43 and the zone 42 are immediately adjacent to each other with a slight clearance therebetween. Similar to the first magnetic shield 33, the second magnetic shield 43 desirably has a multilayer structure (not shown) that includes at least two layers of a ferromagnetic material with a layer of a non magnetic material sandwiched between them. Such a shield 43 works at least as well as using a thicker shield made only of a ferromagnetic shield material. In this embodiment, the second magnetic shield 43 is rotationally symmetrical about the optical axis 27. More specifically, the second magnetic shield 43 comprises a cylindrical portion 43a and a conical portion 43b connected to the cylindrical portion 43a. The conical portion 43b actually is configured as a truncated cone. Hence, the xe2x80x9cinnerxe2x80x9d (or xe2x80x9csecond axis-facingxe2x80x9d as referred to in the claims) surface 43c of the second magnetic shield 43 (i.e., the surface inclined toward the optical axis 27) has a conical shape. By adjusting the parameters of the magnetic field generated by the projection lens 12 to integrate the lens field with the magnetic shield, it is possible to cancel aberrations that otherwise would occur if the magnetic shield were not axially symmetrical at least about the optical axis 27. Third-order and fifth-order aberrations that cannot be cancelled even with the inner surface 43c of the second magnetic shield 43 having a conical shape can be cancelled by adjusting the energization parameters of the reticle-side projection lens 12 (e.g., the energization parameters of the second deflection coil 37), including the second magnetic shield 43. Also, as discussed above regarding the first magnetic shield 33, in this embodiment the inside diameter (at the inner edge 43e of the second magnetic shield 43) is slightly greater than the inside diameter of the second ferrite stack 36. With such a configuration, the second magnetic shield 43 efficiently shields against stray magnetic fields (e.g., from the linear motors 11b of the reticle stage 11) without causing any delay in the time constant of the second deflection coil 37. By configuring and placing the second magnetic shield 43 as described above, stray magnetic fields created between the reticle 10 and the reticle-side projection lens 12 flow smoothly from the second magnetic shield 43 to the upper first vacuum wall 38, thereby preventing inward incursion of such fields. FIG. 4 is a flowchart of steps in a process for manufacturing a microelectronic device such as a semiconductor chip (e.g., an integrated circuit or LSI device), a display panel (e.g., liquid-crystal panel), a charge-coupled device (CCD), a thin-film magnetic head, or a micro-machine, for example. In step S1, the circuit for the device is designed. In step S2, a reticle for a layer of the circuit is fabricated. During this step, local resizing of pattern elements can be performed to correct for, e.g., proximity effects and space-charge effects. In step S3, a wafer (or other suitable substrate) is fabricated from a material such as silicon. Steps S4-S13 are directed to wafer-processing steps, also termed xe2x80x9cpre-processxe2x80x9d steps. In the pre-process steps, the circuit pattern defined on the reticle is transferred onto the wafer by microlithography. More specifically, step S4 is an oxidation step for oxidizing the surface of the wafer. Step S5 involves chemical vapor deposition (CVD) for forming an insulating layer on the wafer surface. Step S6 is an electrode-forming step for forming electrodes on the wafer (typically by vapor deposition). Step S7 is an ion-implantation step for implanting ions (e.g., dopant ions) into the wafer. Step S8 involves application of a resist (exposure-sensitive material) to the wafer. After the wafer is coated with the resist, the wafer is mounted to the surface of an electrostatic wafer chuck according to the invention, as described above. Step S9 involves exposing the resist-coated wafer using CPB microlithography so as to imprint the resist with the reticle pattern, as described elsewhere herein. Step S10 involves exposing the resist as required to a reticle pattern using optical microlithography. Either before or after the CPB microlithography step S9, an auxiliary exposure can be performed to correct for proximity effects from backscattered charged particles. Step S11 involves developing the exposed resist on the wafer. Step S12 involves etching the wafer to remove material from areas where developed resist is absent. Step S13 involves resist stripping, in which remaining resist on the wafer is removed after the etching step. By repeating steps S4-S13 as required, circuit patterns as defined by successive reticles are formed superposedly on the wafer. Step S14 is an assembly step (also termed a xe2x80x9cpost-processxe2x80x9d step) in which the wafer that has been passed through steps S4-S13 is formed into semiconductor chips. This step can include, e.g., assembling the devices (dicing and bonding) and packaging (encapsulation of individual chips). Step S15 is a testing and inspection step in which various operability and qualification tests of the device produced in step S14 are conducted. Afterward, in step S16, devices that successfully pass step S15 are finished, packaged, and shipped. Whereas the invention has been described in connection with a representative embodiment, it will be understood that the invention is not limited to that embodiment. On the contrary, the invention is intended to encompass all modifications, alternatives, and equivalents as may be included within the spirit and scope of the invention, as defined in the appended claims.
	claims	1. A facility for reducing radioactive material, the facility comprising:a cooling water storage unit installed inside a containment building and formed to store cooling water, the cooling water storage unit formed by a structure distinguished from a structure forming the containment building;an opening portion formed at an upper wall of the cooling water storage unit to allow an evaporation of the cooling water therethrough;a boundary unit configured to surround a reactor coolant system installed inside the containment building to form a boundary of radioactive material, the boundary unit configured to suppress spreading of the radioactive material released from the reactor coolant system or a pipe connected with the reactor coolant system to an outside of the boundary;a connecting pipe connected with an inner space of the boundary unit and the cooling water storage unit to guide a flow of a fluid caused by a pressure difference between the boundary unit and the cooling water storage unit from the boundary unit to the cooling water storage unit;a sparging unit disposed to be submerged in the cooling water stored in the cooling water storage unit and connected with the connecting pipe to sparge the fluid that has passed through the connecting pipe and the radioactive material contained in the fluid to the cooling water storage unit;wherein an inside of the containment building comprises:a first area corresponding to the inside of the boundary unit; anda second area formed between (1) an inner wall of the containment building and (2) outer walls of the cooling water storage unit and the boundary unit for accommodating fluid that evaporates through the opening portion, and maintaining a pressure balance with the inside of the cooling water storage unit by the opening portion;a cooling water recollecting portion formed at the upper wall of the cooling water storage unit to recollect fluid condensed in the second area to the cooling water storage unit,wherein the first area is isolated from other spaces inside the containment building excluding an inlet of the connecting pipe,wherein the boundary unit, the connecting pipe and the sparging unit collect the radioactive material in the cooling water storage unit before the radioactive material contacts the inner wall of the containment building, andwherein at least a part of the second area is formed above a top of the first area and a top of the cooling water storage unit, the size of the at least a part of the second area is larger than that of the first area so that the flow of the fluid from the first area to the cooling water storage unit is continued by maintaining a pressure difference between the first area and the second area when a loss-of-coolant accident occurs. 2. The facility of claim 1, wherein the cooling water storage unit includes an inlet through which the connecting pipe passes, and wherein the highest part of the connecting pipe is formed at a predetermined height from a bottom of the cooling water storage unit to prevent the cooling water stored in the cooling water storage unit from flowing back to an inside of the boundary unit. 3. The facility of claim 1, further comprising a check valve formed to allow for a flow only in one direction and installed at the connecting pipe to prevent the cooling water in the cooling water storage unit from flowing back to the boundary unit through the connecting pipe. 4. The facility of claim 1, further comprising:a discharging unit installed at the boundary of the radioactive material to form a fluid path that runs from the boundary unit to the containment building and configured to guide a flow of a fluid caused by a pressure difference between the containment building and the boundary unit from the containment building to the boundary unit through the fluid path; anda filter facility installed in the fluid path of the discharging unit to capture the radioactive material contained in the fluid passing through the discharging unit in the boundary unit. 5. The facility of claim 1, wherein at least a portion of the boundary unit is expanded to a region adjacent to the containment building while surrounding a penetration pipe penetrating the containment building to prevent the loss-of-coolant accident from occurring due to breakage of the penetration pipe in a region between the containment building and the boundary unit. 6. The facility of claim 1, wherein the boundary unit forms a sealing structure around the reactor coolant system to prevent release of the radioactive material. 7. The facility of claim 1, wherein at least a portion of the boundary unit is formed by a concrete structure inside the containment building or a coating member installed on the concrete structure. 8. The facility of claim 1, wherein the boundary unit comprises:a barrier formed to surround the reactor coolant system; anda cover formed to cover an upper part of the reactor coolant system and coupled with the barrier. 9. The facility of claim 4, wherein the filter facility comprises at least one of:a filter configured to form iodic silver by reacting silver nitrate with iodine contained in the fluid and formed to remove the iodic silver from the fluid; andan absorbent configured to remove the iodine contained in the fluid through chemisorption that is performed by charcoal. 10. The facility of claim 4, further comprising a cooling water storage unit installed inside the containment building, the cooling water storage unit formed to store cooling water for dissolving the radioactive material. 11. The facility of claim 10, wherein the discharging unit is extended from the boundary unit to an inside of the cooling water storage unit to discharge the fluid into the cooling water storage unit. 12. The facility of claim 1, wherein the cooling water storage unit is connected with a pipe forming a fluid path that runs to a safety injection line of a safety injection system to inject the cooling water stored in the cooling water storage unit to the inside of the reactor coolant system. 13. The facility of claim 1, further comprising an additive injection unit supplying an additive for maintaining a pH of cooling water to a predetermined value or more to prevent volatilization of the radioactive material dissolved in the cooling water storage unit. 14. The facility of claim 13, wherein the additive injection unit is installed at a predetermined height inside the cooling water storage unit to be submerged in the cooling water as a water level of the cooling water storage unit increases, and wherein as the additive injection unit is submerged in the cooling water, the additive is dissolved in the cooling water. 15. The facility of claim 13, wherein the additive injection unit is installed on a fluid path of the cooling water recollecting portion to dissolve the additive in the cooling water recollected to the cooling water recollecting portion. 16. The facility of claim 1, further comprising a sparging unit installed at an end of a discharging unit to be submerged in the cooling water of the cooling water storage unit and configured to sparge a fluid that has passed through the discharging unit, to condense steam and to dissolve soluble radioactive materials in the discharged air contained in the fluid. 17. The facility of claim 1, wherein the sparging unit comprises:a plurality of sparging holes formed to sparge fluid that has passed through the connecting pipe and the radioactive material contained in the fluid; anda plurality of sub fluid paths that run the plurality of sparging holes from the connecting pipe,wherein the sparging unit has a flow resistance therein to induce an even distribution of the fluid into a plurality of sub fluid paths. 18. The facility of claim 1, further comprising a pressure balance line passing through at least a portion of the boundary unit and extended to an inside of the containment building to form a fluid path of atmosphere passing through the boundary of the radioactive material, wherein the pressure balance line, when a pressure inside the containment building is higher than a pressure inside the boundary unit, introduces atmosphere inside the containment building to the inside of the boundary unit to prevent the cooling water in the cooling water storage unit from flowing back to the inside of the boundary unit. 19. The facility of claim 18, further comprising a check valve formed to allow for a flow only in one direction and installed at the pressure balance line to prevent the atmosphere inside the boundary unit from being discharged to the inside of the containment building through the pressure balance line. 20. The facility of claim 1, wherein the cooling water storage unit is connected with a pipe forming a fluid path that runs to a safety injection line of a safety injection system to inject the cooling water stored in the cooling water storage unit to the inside of the reactor coolant system. 21. The facility of claim 4, wherein at least a portion of the boundary unit is expanded to a region adjacent to the containment building while surrounding a penetration pipe penetrating the containment building to prevent the loss-of-coolant accident from occurring due to breakage of the penetration pipe in a region between the containment building and the boundary unit. 22. The facility of claim 4, wherein the boundary unit forms a sealing structure around the reactor coolant system to prevent release of the radioactive material. 23. The facility of claim 4, wherein at least a portion of the boundary unit is formed by a concrete structure inside the containment building or a coating member installed on the concrete structure. 24. The facility of claim 4, wherein the boundary unit comprises:a barrier formed to surround the reactor coolant system; anda cover formed to cover an upper part of the reactor coolant system and coupled with the barrier. 25. The facility of claim 16, wherein the sparging unit has a flow resistance therein to induce an even distribution of the fluid into a plurality of sub fluid paths. 26. The facility of claim 10, further comprising a pressure balance line passing through at least a portion of the boundary unit and extended to an inside of the containment building to form a fluid path of atmosphere passing through the boundary of the radioactive material, wherein the pressure balance line, when a pressure inside the containment building is higher than a pressure inside the boundary unit, introduces atmosphere inside the containment building to the inside of the boundary unit to prevent the cooling water in the cooling water storage unit from flowing back to the inside of the boundary unit.
	claims	1. A method for using a molten salt reactor, the method comprising:obtaining a molten salt reactor comprising:a tubular reactor core comprising graphite and defining an internal space; anda fuel wedge that comprises graphite and defines multiple fuel channels, wherein the fuel wedge is received within the internal space, wherein an outer surface of the fuel wedge comprises a first contoured shape, wherein an internal surface of the internal space comprises a second contoured shape, wherein the first contoured shape of the fuel wedge substantially corresponds in shape and contacts the second contoured shape of the internal surface of the tubular reactor core as the molten salt reactor operates, and wherein the fuel channels allow a molten fissionable fuel to flow from a first end of the fuel wedge to a second end of the fuel wedge, andflowing the molten fissionable fuel through the fuel channels. 2. The method of claim 1, wherein the tubular reactor core is disposed within, and is in contact with, a reflector comprising graphite. 3. The method of claim 1, wherein the fuel wedge comprises:a first section comprising a first portion of the fuel channels; anda second section comprising a second portion of the fuel channels,wherein the first section and the second section are disposed end to end within the internal space such that the first and second portions of the fuel channels are aligned so that the fissionable fuel flows from the first portion to the second portion of the fuel channels during reactor operation,wherein an alignment pin extends between the first section and the second section of the fuel wedge to keep the first and second portions of the fuel channels aligned end to end, andwherein a seal comprising graphite is disposed between the first section and the second section of the fuel wedge. 4. The method of claim 2, wherein the reflector is disposed within, and in contact with a metal housing. 5. A method for providing a molten salt reactor, the method comprising:forming a reactor core that comprises graphite and multiple fuel channels that are configured to allow a molten salt comprising a fissionable fuel to flow from a first end to a second end of the reactor core;forming a reflector that comprises graphite and defines an internal surface that substantially conforms to, and is in contact with, an external shape and external surface of a portion of the reactor core as the molten salt reactor operates; andplacing the reactor core within, and in contact with, the reflector,wherein the reactor core comprises a tubular reactor core that defines an internal space, wherein the method further comprises forming a fuel wedge that comprises graphite and defines at least some of the fuel channels, and wherein the method further comprises placing the fuel wedge within the internal space such that an outermost surface of the fuel wedge contacts and tracks an interior surface of the internal space of the tubular reactor core. 6. The method of claim 5, further comprising placing the reflector and the reactor core in a metal housing such that the metal housing substantially envelopes the reflector. 7. The method of claim 5, further comprising joining a first wedge section and a second wedge section together, end to end, to form the fuel wedge such that the fissionable fuel flows from the first wedge section to the second wedge section as the molten salt reactor operates. 8. The method of claim 7, further comprising placing an alignment pin between the first wedge section and the second wedge section to align portions of the fuel channels in the first wedge section with portions of the fuel channels in the second wedge section such that the fissionable fuel flows from the first wedge section to the second wedge section as the molten salt reactor operates. 9. The method of claim 5, wherein the fuel wedge comprises a substantially sector-shaped prism configuration with an external arc shaped surface of the sector-shaped prism being in contact with and substantially following the interior surface of the internal space of the tubular reactor core. 10. The method of claim 5, further comprising forming the reflector by coupling multiple reflector components together around, and in contact with, the reactor core. 11. A method for providing a molten salt reactor, the method comprising:forming a reactor core tube comprising graphite and defining an internal space;disposing in the reactor core tube an internal moderator that comprises graphite and defines a fuel channel that is configured to allow a molten salt comprising a fissionable fuel to flow from a first end to a second end of the reactor core tube;forming a reflector that comprises graphite and defines an internal surface that substantially conforms to an external shape and external surface of a portion of the reactor core tube;placing the reactor core tube within the reflector such that the internal surface of the reflector is in contact with the external shape and surface of the portion of the reactor core tube:,coupling a first end cap at a first end of the reactor core tube such that the first end cap is configured to direct the molten salt from a fuel inlet in the first end cap to the fuel channel; andcoupling a second end cap at a second end of the reactor core tube such that the second end cap is configured to direct the molten salt from the fuel channel to a fuel outlet in the second end cap. 12. The method of claim 11, further comprising placing the reflector, which houses and is in contact with the reactor core tube, and the internal moderator, which is disposed in, and in contact with, the reactor core tube, within a housing comprising a nickel alloy such that the housing substantially envelopes the reflector. 13. The method of claim 11, further comprising obtaining a diffuser plate defining a plurality of holes, wherein the diffuser plate is configured to at least one of (i) diffuse and (ii) direct the fissionable fuel from the fuel inlet of the first end cap towards the fuel channel, and disposing the diffuser plate between a portion of the first end cap and a portion of the internal moderator. 14. The method of claim 11, wherein the internal moderator comprises a first, second, and third fuel wedge that each have a sector-shaped prism configuration, that each define multiple fuel channels, and that each have an external arc shaped surface of the sector-shaped prism that is in contact with and that substantially follows an interior surface of the internal space of the reactor core tube. 15. The method of claim 14, further comprising joining a first fuel wedge section and a second fuel wedge section together, end to end, to form the first fuel wedge such that the fissionable fuel is able to flow from the first fuel wedge section through the second fuel wedge section. 16. The method of claim 15, further comprising placing an alignment pin between the first fuel wedge section and the second fuel wedge section to keep the fuel channels of the first fuel wedge in fluid communication between the first fuel wedge section and the second fuel wedge section of the first fuel wedge. 17. The method of claim 15, further comprising forming a seal comprising graphite between the first and second fuel wedge sections, wherein the seal is configured to retain the fissionable fuel within the first fuel wedge between the first fuel wedge section and the second fuel wedge section. 18. The method of claim 14, wherein the method further comprises forming a seal between the first and second fuel wedges, along a length of the first and second fuel wedges.
050930753	claims	1. In a nuclear reactor comprising a pressure vessel closed by a removable cover and including at least one coolant input nozzle and at least one coolant output nozzle situated in the vicinity of the cover, a core formed of fuel assemblies and in which the coolant flows upwardly and a plurality of vertically movable control clusters actuated by drive shafts projecting through the cover of the reactor, upper internals positioned above said core, said upper internals including: wherein each of said cluster guides of the flow fractionating device comprises an outer casing devoid of openings, having a substantially coolant-tight connection with said lower plate and upper plate and having a substantially coolant-tight connection with a respective one of said guide tubes, each of said guide tubes having a lateral wall devoid of openings in said collection assembly and opening into a volume formed under said cover; said upper internals further comprising a cylindrical barrel located within the vessel and cooperating with an inner surface of said vessel for defining a passage for coolant circulation from the input nozzle downwardly to a space from which said coolant flows upwardly into the fuel assemblies, said barrel being connected to the vessel by a flange formed with means for delivery of a controlled flow of cold coolant, at a pressure higher than that of the coolant flowing out of the core, from the input nozzle to said volume under the cover, from the cover to the upper end of each of said guide tubes, and from the lower end of each of said guide tubes to a respective one of said cluster guides. a collection assembly for collecting the coolant and directing it toward the output nozzle, having a plurality of guide tubes, each aligned with a respective one of said fuel assemblies, each for receiving one of said drive shafts, each having a lateral wall devoid of openings and each opening upwardly into a volume formed under said cover and fed with coolant from the input nozzle, a radial clearance being reserved between the drive shaft and the lateral wall for defining a downward coolant flow from said volume; and a device located between the core and the collection assembly for fractionating the coolant flow exiting from the core, including: said lower plate being formed with second passage means located between said cluster guides, cooperating with said first passage means for providing a coolant path from said core to said collection assembly around said cluster guides, said upper internals further comprising a cylindrical barrel located within the vessel and cooperating with an inner surface of said vessel for defining a passage for coolant circulation from the input nozzle downwardly to a space from which said coolant flows upwardly into the fuel assemblies, said barrel being connected to the vessel by a flange formed with means for delivery of a controlled flow of cold coolant, at a pressure higher than that of the coolant flowing out of the core, from the input nozzle to said volume under the cover, from the cover to the upper end of each of said guide tubes, and from the lower end of each of said guide tubes to a respective one of said cluster guides. 2. Upper internals according to claim 1, wherein the casings of at least some of the cluster guides are secured to one of the upper and lower plates and are slidably received in the other one of said upper and lower plates for free expansion and retraction therein. 3. Upper internals according to claim 1, wherein each of said cluster guides in the separation device has a plurality of vertically distributed horizontal plates, some at least of the plates being secured to the respective casing. 4. In a nuclear reactor comprising a pressure vessel closed by a removable cover and including at least one coolant input nozzle and at least one coolant output nozzle situated in the vicinity of the cover, a core formed of fuel assemblies and in which the coolant flows upwardly and a plurality of clusters of control rods vertically movable into and out of respective ones of said fuel assemblies by respective drive shafts projecting through the cover of the reactor, upper internals positioned above the core, said upper internals including: 5. Upper internals according to claim 4, wherein said radial clearance is greater in some of said guide tubes than in the other ones of said guide tubes for causing a greater downward coolant flow to occur from said volume to said core.
046845011	summary	BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates generally to fuel assemblies for a nuclear reactor and, more particularly, is concerned with compliant inserts mounted within holes in the upper tie plate of a BWR fuel assembly for supporting the upper end plug extensions of assembly fuel rods so as to prevent binding and axial loading of the fuel rods. 2. Description of the Prior Art Typically, large amounts of energy are released through nuclear fission in a nuclear reactor with the energy being dissipated as heat in the elongated fuel elements or rods of the reactor. The heat is commonly removed by passing a coolant in heat exchange relation to the fuel rods so that the heat can be extracted from the coolant to perform useful work. In nuclear reactors generally, a plurality of the fuel rods are grouped together to form a fuel assembly. A number of such fuel assemblies are typically arranged in a matrix to form a nuclear reactor core capable of a self-sustained, nuclear fission reaction. The core is submersed in a flowing liquid, such as light water, that serves as the coolant for removing heat from the fuel rods and as a neutron moderator. Specifically, in a boiling water reactor (BWR) the fuel assemblies are typically grouped in clusters of four with one control rod associated with each four assemblies. The control rod is insertable within the fuel assemblies for controlling the reactivity of the core. Each such cluster of four fuel assemblies surrounding a control rod is commonly referred to as a fuel cell of the reactor core. A typical BWR fuel assembly in the cluster is ordinarily formed by a N by N array of the elongated fuel rods. The bundle of fuel rods are supported in laterally spaced-apart relation and encircled by an outer tubular channel having a generally rectangular cross-section. The outer flow channel extends along substantially the entire length of the fuel assembly and interconnects a top nozzle with a bottom nozzle. A hollow water cross extends axially through the outer channel so as to provide an open inner channel for subcooled moderator flow through the fuel assembly and to divide the fuel assembly into four, separate, elongated compartments, each containing an identical mini-bundle of the fuel rods. The bottom nozzle fits into the reactor core support plate and serves as an inlet for coolant flow into the outer channel of the fuel assembly. Coolant enters through the bottom nozzle and thereafter flows through the water cross and along the fuel rods removing energy from their heated surfaces. The fuel rods of each mini-bundle extend in laterally spaced apart relationship between an upper tie plate and a lower tie plate and connected together with the tie plates comprises a separate fuel rod subassembly within each of the compartments of the channel. A plurality of grids axially spaced along the fuel rods of each fuel rod subassembly maintain the fuel rods in their laterally spaced relationships. The water cross has approximately the same axial length as the fuel rod subassemblies, extending between the upper and lower tie plates thereof. In each fuel rod subassembly of the BWR fuel assembly, the mini-bundle of fuel rods is composed of standard fuel rods and tie rods. Such use of standard and tie fuel rods is conventional, as can be seen in BWR fuel bundles illustrated in U.S. patents to Qurnell et al (U.S. Pat. No. 3,741,868) and Smith et al (U.S. Pat. No. 4,022,661). Ordinarily, the tie rods have extensions with nuts on the ends thereof which limit movement within holes in the upper tie plate, whereas the standard fuel rods have upper end plug extensions which are slidably received within holes in the plate. The upper tie plate is positioned axially by the tie rods, whereas the top ends of all the fuel rods, including the tie rods, are positioned and supported laterally by the upper tie plate via the pattern of holes defined therein. Since thermal and irradiation growth rates may be different between the tie rod and the standard fuel rod, especially in fuel assembly designs where the fuel cladding is made of cold-worked Ziracaloy, the end plug extension on the standard fuel rod must slide freely in its receiving hole in the upper tie plate to accommodate relative growth in length between the tie and standard fuel rods. Otherwise, binding and an axial load in the fuel rod would result, which leads to bowing of the fuel rod. Consequently, a need exists for a way to prevent binding of the upper end plug extension within the upper tie plate hole in order to avoid axial loading and resultant bowing of the fuel rod. SUMMARY OF THE INVENTION The present invention provides a compliant insert for supporting the end plug extension in the tie plate hole in a manner which is designed to satisfy the aforementioned needs. The compliant insert of the present invention provides a solution to the binding problem in the upper tie plate holes by interposing resiliently flexible spring support members within the respective hole (after being slightly enlarged in diameter) between the end plug extension and the hole sidewall which will accommodate relative angular movement between the end plug extension and tie plate, such as due to tilting of the tie plate relative to the plug extension, while still allowing axial movement of one relative to the other. Although, spring-type members have been incorporated heretofore in fuel assembly grids or spacers for engaging fuel rods to support them in a desired array, such as disclosed in U.S. patents to Ashcroft et al (U.S. Pat. No. 3,361,639), Milburn (U.S. Pat. No. 3,801,452) and Amaral et al (U.S. Pat. No. 4,089,742), the art has failed to either perceive the above-described binding problem existing heretofore between the fuel rod end plug extension and upper tie plate or the possibility of using a compliant insert as the solution thereof. Accordingly, the present invention is set forth in a fuel assembly having a plurality of fuel rods, a plurality of grid structures axially spaced from one another along the fuel rods and supporting the fuel rods in a side-by-side spaced array, and tie plates disposed at opposite ends of the fuel rods. At least one of the tie plates has a plurality of holes defined by endless sidewalls formed therethrough between opposite sides of the tie plate and in an array which matches that of the fuel rods. Each of the fuel rods has a pair of end plugs sealing opposite ends thereof with at least one of the end plugs having an extension member thereon which extends axially outward therefrom. The present invention relates to a compliant insert disposed in each of the holes of the one tie plate and including a plurality of spring members engaged with the tie plate and the end plug extension member so as to support the extension member within the hole in spaced relationship from the hole sidewall. In one embodiment, the spring members are separate from one another, whereas in another embodiment, they are integrally connected to one another. More particularly, each of the spring members has opposite end portions disposed along opposite sides of the tie plate adjacent to the tie plate hole. In one embodiment, the opposite end portions are tabs being bendable between axially-extending releasing and radially-extending securing positions. In addition, means are provided for securing the opposite end portions of each spring member to the respective sides of the tie plate. In one embodiment, the securing means are indentations formed in the respective sides of the tie plate into which the opposite end portions of the spring members extend. In another embodiment, the securing means are welds which interconnect the opposite end portions of the spring members to the respective sides of the tie plate. Still further, each of the spring members has an elongated middle portion extending through the plate hole between the hole sidewall and the extension member, and resilient means defined on each spring member middle portion engaging and positioning the extension member in spaced relationship from the hole sidewall. In one embodiment, the resilient means is a single inwardly-protruding dimple formed on the middle portion of the spring member. In another embodiment, the resilient means is a pair of tandemly-arranged inwardly-protruding dimples formed on the middle portion of the spring member. Also, the present invention relates to the combination in a fuel assembly, comprising: (a) a plurality of elongated fuel rods, each of the fuel rods having a pair of end plugs sealing opposite ends thereof, at least the end plug at one of the opposite ends of each fuel rod having an extension member thereon which extends axially outward from the end plug and is of a diameter less than that of the fuel rod; (b) a plurality of grid structures axially spaced from one another along the fuel rods between the opposite ends thereof and supporting the fuel rods in a side-by-side spaced array; (c) a pair of tie plates disposed at the respective opposite ends of the fuel rods, at least one of the tie plates having a plurality of holes defined by endless sidewalls formed therethrough between opposite sides of the tie plate and in an array which matches that of the fuel rods; and (d) a compliant insert disposed in each of the holes of the one tie plate and engaged with the tie plate and the end plug extension member so as to yieldably support the extension member within the hole in spaced relationship from the hole sidewall. 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.
039309401	abstract	A nuclear fuel sub-assembly comprises a bundle of fuel pins provided with helical spacers and located within a shroud for the coolant. The sub-channels at the periphery of the bundle are restricted in order that the rate of flow matches the heat transfer surfaces in all sub-channels. For this purpose the spacers of the outer pins project radially by an extent smaller than the spacers of the inner pins. In addition longitudinal ribs may be provided in the outer sub-channels.
048333352	abstract	A neutron shielded door has a hollow interior portion for containing a neutron retarding fluid. This neutron retarding fluid may consist of hydrogen rich compound, such as water, with a dissolved boron compound. This door contains internal baffles for preventing surging of the neutron retarding fluid when the door is opened and closed. The neutron shielded door is contemplated for use with radiation therapy rooms housing medical accelerators and other equipment which generate low levels of neutrons. Ports are provided for the input and drainage of neutron retarding fluid from the door and fluid indicators are provided for permitting determination of the amount of fluid contained in the door.
047754940	claims	1. An improved method of solidifying a radioactive or hazardous liquid comprising placing said liquid in a container and adding only sodium montmorillonite to said liquid in a ratio of sodium montmorillonite:liquid of between about 3:1 and 1:7, respectively, until the composition comprises an unpourable, free standing solid. 2. A method of solidifying a radioactive or hazardous liquid comprising at least about 95% water by adding only sodium montmorillonite having a major portion of particles between about 3/8 inch and 20 mesh thereto in a sodium montmorillonite:liquid ratio of between about 1:2 and about 1:7, respectively, in fractions with at least a few minutes interval between fractions, until the composition comprises an unpourable, free standing solid. 3. The method of claim 2 wherein each of said fractions is between about 10 and 50% of the total amount added. 4. The method of claim 2 wherein each of said fractions is between about 1/3 and 1/4 of the total amount added and wherein the intervals between fraction additions is at least about 10 minutes. 5. The method of claim 2 comprising placing between about 40 and 50 gallons of said liquid in a 55 gallon drum, and adding between about 150 and about 175 pounds of sodium montmorillonite to said liquid in fractions of between about 40 and about 55 pounds with at least about 10 minute intervals between fractions. 6. A method of solidifying a radioactive or hazardous liquid comprising at least about 5% hydrocarbon by adding only sodium montmorillonite having a major portion of particles of about 200 mesh or smaller thereto in a sodium montmorillonite:liquid ratio of between about 1:2 and 3:1, respectively, with stirring, until the composition comprises an unpourable, free standing solid.
053176120	description	DETAILED DESCRIPTION OF THE INVENTION The present invention provides fuel pellet holddown springs which are able to maintain adequate holddown force on the fuel pellet stack after one or more heatup cycles. The fuel pellet holddown springs of the present invention can also provide substantial holddown force at both high (operational) and low (ambient) temperatures. According to an embodiment of the present invention, a fuel pellet holddown spring is provided which comprises a shape-memory alloy. Shape-memory alloys are well known in the art. See, for example, C. M. Wayman, Journal of Metals, pp. 129-137, June 1980; Encyclopedia of Materials Science and Engineering, MIT Press, Cambridge, Mass., Vol. 6, pp. 4635-4674 (1986); and Kirk-Othmer Encyclopedia of Chemical Technology, John Wiley & Sons, New York, Vol. 20, pp. 726-736 (1982), the disclosures of which are incorporated herein by reference. When an ordinary metal is strained beyond its elastic limit, permanent deformation of the material is produced. For most metals, this yield point corresponds to a fraction of a percent strain. Any strain beyond this point is defined as plastic deformation and is expected to remain. For example, it would be very surprising if an extensively kinked metal wire were to straighten out spontaneously when heated. However, this is exactly what certain shape-memory alloys are able to do. If one of these alloys is deformed below a critical temperature, it may recover its original unbent shape when it is reheated. The reheating "reminds" the alloy that it prefers a different crystal structure and associated shape at higher temperature. This unusual behavior has been termed the "shape-memory effect." Without being held to any particular theory, it is currently believed that the shape-memory effect is based on the continuous appearance and disappearance of the martensite phase with falling and rising temperatures. This thermoelastic behavior is the result of the transformation from a parent phase stable at elevated temperature to the martensite phase. A specimen in the martensite phase may be deformed in what appears to be a plastic manner but is actually deforming as a result of the growth and shrinkage of self-accommodating martensite plates. When the specimen is heated to the temperature of the parent phase, a complete recovery of the deformation takes place. Complete recovery in this process is limited by the fact that strain must not exceed a critical value which ranges, for example, from 3-4% for copper shape-memory alloys to 6-8% for nickel-titanium shape-memory alloys. According to FIG. 1, the temperature T at which the martensite phase starts to form from the parent phase on cooling is referred to as M.sub.s and the temperature at which the parent phase has been completely transformed to the martensite phase is M.sub.f. On heating a martensitic specimen, the temperature at which the transformation begins to reverse to the parent phase is designated P.sub.s. The reverse transformation to the parent phase is completed at a higher temperature designated P.sub.f. Although a single parent phase typically forms on heating, the martensite phase usually displays a number of variants on cooling. Note that there is typically a slight hystersis between the forward and reverse transformation ranges, so that the transformation from parent phase to the martensite phase on cooling occurs over a slightly lower range (M.sub.s to M.sub.f) than the reverse transformation on heating (P.sub.s to P.sub.f). The range M.sub.s to M.sub.f is herein referred to as the "martensite transformation temperature range"; the range P.sub.s to P.sub.f is herein referred to as the "parent transformation range". The temperature range encompassing M.sub.s, M.sub.f, P.sub.s and P.sub.f is defined herein as the "overall transformation temperature range." It is possible to condition or "train" a shape-memory effect alloy to have a two-way shape-memory effect. The two-way shape-memory effect is a spontaneous, reproducible, reversible shape change associated with heating and cooling throughout the overall transformation temperature range. The reversible shape change could be, for example, bending and unbending or twisting and untwisting as the trained shape-memory effect alloy sample is cycled between the M.sub.f and P.sub.f temperatures (i.e., through the overall transformation temperature range). Alloys for which two-way shape-memory effect has been observed include Cu-A, Cu-Zn-A, In-T and Ti-Ni. This two-way shape-memory conditioning is apparently brought about by limiting the number of martensite variants that form upon cooling through the application of an external stress during the transformation. It is believed that the limit imposed upon the number of variants formed reduces the self-accommodating feature of the usual transformation and increases the residual stress. By repeating the process a number of times, the restricted variant group and its associated internal stress spontaneously revert to the parent phase on heating and then to a singular martensite group on cooling. The two-way shape-memory training procedure can be illustrated by the following examples: (a) A straight wire is cooled below M.sub.f and bent to a desired shape. The bending stress is accommodated by the formation of a reduced number of preferred variants of martensite plates. The specimen is then heated to a temperature above P.sub.f and becomes straight again. This procedure is repeated 20-30 times. This completes the training, and the sample now bends to its programmed shape when cooled below M.sub.f and becomes straight when heated above P.sub.f. After the initial training, the reversible shape change associated with cooling and heating may be repeated indefinitely. (b) The wire is deformed or bent above M.sub.s to produce preferred variants of stress-induced martensite and is then cooled below M.sub.f. Upon subsequent heating above P.sub.f the wire becomes straight again. This procedure is repeated about 20-30 times to complete the memory training. Thus, once the two-way shape-memory effect has been achieved, a specimen can, for example, assume a stable high temperature configuration when the metal is raised above P.sub.f and assume a stable low temperature configuration when the metal is cooled below M.sub.f. Cloue U.S. Pat. No. 4,699,757 describes the use of shape memory alloys in fuel pellet holddown devices. It is directed, however, to a radially expandable element having a cross-sectional area such that it frictionally engages an internal surface of the fuel rod cladding. When the fuel rod is brought up to reactor operating temperature, the radially expandable element if contracted clear of frictional contract by means of a shape-memory alloy. U.S. Pat. No. 4,699,757 is concerned with holding down the fuel on the pellet stack only during transport and handling of the rods. In contrast, the holddown spring of the present invention does not concern radial expansion, and it is used to maintain force on the pellet stack during both thermal expansion and contraction of the pellet stack. Fuel pellet holddown springs formed from a shape-memory alloy can be designed such that the holddown spring expands to a high temperature configuration (parent phase) when heated to a temperature above the overall transition temperature range and contracts to a low temperature configuration (martensite phase) when cooled to a temperature below the overall transition temperature range. Of course, the shape-memory holddown spring will exert a greater force at high temperatures than at low temperatures. The transition temperature range, as well as the relative forces exerted by holddown springs constructed from shape-memory alloys, can be adjusted by varying the specific alloy compositions. The relative force exerted will also be determined by the degree of preliminary spring compression and by the treatment during the "programming" of the shape-memory alloy holddown spring. Essentially any shape-memory alloy can be used in the present invention so long as it demonstrates adequate two-way shape-memory effect and possesses an overall transition temperature range substantially above room temperature and substantially below the temperature of the environment to which the shape-memory alloy is subjected during reactor operation. Shape-memory alloys also preferably exhibit good corrosion resistance under reactor operating conditions and ideally exhibit low neutron capture cross-section. Presently preferred shape-memory alloys for the practice of the present invention include nickel-titanium alloys (also known as Tinel alloys) such as Raychem's K or BH alloys. Nickel-titanium alloys exhibit a narrow hystersis curve, with their strength varying dramatically from one phase to the other. This results in low reset forces and excellent fatigue life. The overall configuration of the holddown spring is preferably a coil configuration, but other configurations such as that of a simple compressed arch will readily become apparent to those of skill in the art. A presently preferred embodiment is shown in FIGS. 2 and 3. A fuel rod 10 is depicted wherein a fuel pellet stack 11 within a fuel rod cladding 12 is compressed by means of a composite holddown spring 14 interposed between the fuel pellet stack 11 and a fuel rod end cap 13. The composite holddown spring 14 comprises a conventional spring portion 15, such as that of stainless steel, and a shape-memory alloy spring portion 16, such as that of a nickel-titanium alloy. The composite holddown spring 14 is used to exert a continuous force on the fuel pellet stack 11 during all phases of operation, including shipping and operation. As discussed above, the shape-memory alloy spring portion 16 of the composite holddown spring 14 can be constructed such that it expands to a high temperature configuration at temperatures above the overall transition temperature range of the alloy and contracts to a low temperature configuration at temperatures below the overall transition temperature range. Somewhat conversely, the conventional spring portion 15 of the composite holddown spring 14 weakens, and is thus compressed, at high temperatures and strengthens, and thus expands, at low temperatures. FIG. 2 shows the configuration of the composite spring 14 at low (ambient) temperatures. FIG. 3 shows the configuration of the composite spring 14 at high (operating) temperatures. As shown in FIG. 3, when reactor coolant temperatures increase, the shape memory alloy spring portion 16 expands while the conventional spring portion 15 contracts. As shown in FIG. 2, when coolant temperatures decrease, the shape memory alloy spring portion 16 contracts while the conventional spring portion 15 expands. Since a self-locking stainless steel spring is currently being sold by Combustion Engineering, Inc., the conventional spring portion 15 is preferably inserted last. Nevertheless, if it is found to be advantageous to place the conventional spring portion 15 against the fuel pellet stack 11 and insert the shape memory alloy spring portion 16 last (e.g., due to temperature or neutron flux considerations), this change could be easily made. It is believed that significant hydrogen concentration may cause failures in shape-memory alloys due to hydrogen embrittlement. However, in fuel rods, hydrogen levels are very low with limits of 0.6 ppm set for the fuel pellets. It is, therefore, believed that hydrogen embrittlement will not be a problem in present invention. Although there are many additional specific designs which can be developed from the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention, and without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions.
	abstract	Apparatus and methods for controlling a radiotherapy electron beam. Exemplary embodiments provide for focusing the electron beam at different depths by altering parameters of a plurality of magnets. Exemplary embodiments can also provide for focusing the electron beam at different depths while maintaining the energy level of the electron beam at a consistent level.
048809896	description	DETAILED DESCRIPTION OF THE INVENTION The shielding apparatus and container 20 is illustrated generally in FIG. 1. Container 20 has an outer shell 24 upon which is located a closure lid 22. Lid 22 is hingedly connected to outer shell 24 and can be secured to outer shell 24 by handle members 26 (one of which is illustrated) which are also hingedly connected to the outer shell 24. The members 26 function both as handles and as a closure means for the container. As can best be seen in FIGS. 2 and 4, container 20 is provided with an inner shell 27 which is supported on and in outer shell 24. Inner shell 27 is formed with a top portion 28 which is adapted to be bonded to outer shell 24 around the periphery thereof. Inner shell 27 additionally has a lower portion 29 formed by outer wall 32 and inner wall 34 . A cover shield 30, which will be described more fully hereinafter, is adapted to fit within the surfaces defined by inner wall 34 of the lower portion 29. Outer wall 32 and inner wall 34 define a channel 36 therebetween which can be filled with a suitable radiation shielding material (not shown) such as lead shot or the like. Inner wall 34 defines a nebulizer well 38 which generally conforms to the contours of the nebulizer 82 when it is located within well 38. A support pad 40 is provided at the bottom of well 38 and secured thereto by means of screws 46 which can be seen most clearly in FIG. 4. A radial slot 48 is formed in the support pad 40 to accommodate the bottom portion 85 of nebulizer 82. Also provided in nebulizer well 38 are retaining spring elements 42 which are suitably formed from spring steel or the like and are adapted to contact the wall of nebulizer 82 to maintain it in a stable and upright position during use. Attached to the bottom of outer wall 32 is a plate 44 which is utilized to cover the opening through which lead shot or other suitable shielding material can be loaded into channel 36. Alternatively, the shielding material can be placed within channel 36 during the molding process. Inner wall 34 is contoured and includes a ramp sidewall 50 which defines a ramp 52 extending about the periphery of inner wall 34 from the bottom of well 38 to the top of well 38 and eventually to groove 58 in the hemicylindrical surface 54 formed at one end of the inner shell 27. A hemicylindrical surface 56, similar to the hemicylindrical surface 54, is formed at the other end of the inner shell 25. Ramp 52 is utilized to support a fluid delivery tube which extends from inlet port 84 on nebulizer 82 upwardly upon ramp 52 through groove 58 where it can be attached to a source of air or oxygen to drive nebulizer 82 in a conventional manner. Ramp 52 provides a convenient mechanism for ensuring that the fluid delivery tube 86 does not kink or become unduly twisted and thus prevent fluid delivery and operation of the nebulizer 82. Handles 26 are hingedly connected at pivot points 31 to outer shell 24 and are adapted to engage lid 22 in the closed position. Only one hinge mechanism has been illustrated but it is understood that handle 26 on the other side of container 20 is connected in the same fashion. Handle 26 is additionally provided with radiation shielding material 45 in the form of a lead plate or the like. Inner wall 34 also defines a support surface 33 about the periphery of inner shell 27 dimensioned to mate with cover shield 30, which is formed with the same design about its periphery. Cover shield 30 is formed with a contoured top plate 60 on which is mounted a handle 62. Attached to the bottom of top plate 60 is a contoured shield plate 64 which is made from radiation shielding material. Both top plate 60 and shield plate 64 are formed with a hole 66 extending therethrough to accommodate a movable latch 70 which is utilized to engage the manifold 88. Movable latch 70 is pivotably attached to a latch support 68 at pivot point 71. Latch 70 is formed with a surface 72 and latch support 68 is formed with a surface 74 which are adapted to engage a portion of the manifold 88. Latch surface 72 is movable, whereas latch surface 74 remains fixed. A spring-loaded latch rod 76 is provided between latch 70 and latch support 68 in order to bias latch 70 to its engaged position. Latch rod 76 is conveniently located within a bore formed in latch support 68. Latch support 68 is conveniently attached to cover shield 30 by means of screws 77. Means to retain cover shield 30 are provided by means of pivotable arms 78 which are connected to the top portion 28 of inner shell 27 and adapted to be moved over the cover shield 30 when it is in position. The contours of cover shield 30 define a filter well 80 which is adapted to accommodate filter 90 when it is in place as part of the transport means for the radioaerosol, as illustrated most clearly in FIG. 3. FIG. 3 illustrates generally the relative positions of the various components of the apparatus when the radioaerosol system is in use. As can be seen therein the nebulizer 82 is positioned on support pad 40 in well 38 and retained by spring members 42 in a stable and upright position. The lower end of the nebulizer 82 is provided with a connector 84 which is adapted to receive the end of a fluid supply tube 86 which is supported on ramp 52 and directed through the groove 58 formed in inner shell 27. Fluid supply tube 86 is connected to a source of air or oxygen to drive the nebulizer in a conventional manner. The top of nebulizer 82 is formed with a molded, inner ring 83 which is adapted to locate within a groove 118 on a connector 116 at the bottom of the manifold 88, as can be seen most clearly in FIG. 11. The nebulizer 82 is connected to the manifold via connector 116 and the manifold 88 is engaged by movable latch 70 and thus is secured to cover shield 30. End 104 of manifold 88 is connected to a biological filter 90 and the other end 106 of manifold 88 is connected to a patient breathing tube 94 which, extends to the mouthpiece of the patient. An extension 92 is placed on the end of filter 90 to assist in the support of the transport means within the shielding container. When cover shield 30 is attached to manifold 88, as can best be seen in FIG. 12, cover shield 30 and the transport means (including manifold 88, filter 90, filter extension 92 and nebulizer 82) and the radioaerosol generating source, i.e., the nebulizer 82, can be removed from the shielding container as a unit. Thus, in removing that system as a unit from the shielding container, the operator still is protected cover shield 30 in handling the manifold 88, filter 90, filter extension 92 and nebulizer 82 and associated tubing which may be contaminated with radioactive material. The entire unit can then be placed over a suitable disposal container and when latch 70 is pivoted to release manifold 88, nebulizer 82, filter 90 and associated tubing also are released so that all of the contaminated components will be disposed of without unduly endangering an operator. As can be seen most clearly in FIG. 11, the manifold 88 is formed with an upper section 96 and a lower section 98 which when joined together form an inlet conduit 100 and an outlet conduit 102 which join at one end to form a connector 104 which is adapted to connect to the filter 90 and at the other end form a connector 106 which is adapted to connect to the patient breathing tube 94. Inlet conduit 100 and outlet conduit 102 define an opening 120 which is provided with a lip extending outwardly from conduit 100 and 102 into the opening. The function of lip 122 is to be engaged by surfaces 72 and 74 on the latching mechanism. A one-way check valve 112 is situated in a groove 108 formed in inlet conduit 100 between connector 104 and connector 116. Valve 112 is conventional and can be of the diaphragm type. Valve 112 permits flow from the atmosphere through the filter from connector 104 in a direction toward connector 106 though inlet conduit 100. However, the one-way nature of valve 112 will prevent fluid flow in the reverse direction, for example when the patient exhales. In a similar manner, a one-way valve 114 is provided in a groove 110 in outlet conduit 102. One-way valve 114 can again be of the diaphragm type and will permit flow in a direction from connector 106 though outlet conduit 102 to connector 104. Valve 114 will, however, prevent flow in the opposite direction. As described above, latch support 68 and latch 70 are adapted to fit within opening 120 such that surfaces 72 and 74 can engage the lower portion of lip 122 formed on inlet conduit 100 and outlet conduit 102. While lip 122 extends entirely around the periphery of opening 120, it is understood that only portions thereof would have to be provided in order to attach manifold 88 to cover shield 30. In the event it is not appropriate to dispose of the transport means and the nebulizer 82 immediately after use, the patient tube 94 can be disconnected and the fluid delivery tube 86 can be disconnected from the source of air on oxygen and handles 26 can be moved upwardly and latched to lid 22 to position radiation shielding material 45 over the ends of the openings in the outer shell at each side of the container. Thus the container 20 effectively isolates the radioactive material from the surrounding atmosphere and the radioactive material can be left within container 20 until such time as the level of radioactivity has been reduced to a point that the disposal is appropriate. During operator use, lid 22 is elevated and an aerosol generator, such as nebulizer 82 is connected to the fluid delivery tube 86 and positioned within the bottom of well 38 upon support pad 40. Tube 86 is supported on ramp 52 and directed through groove 58. A radiolabeled solution such as .sup.99m technetium diethylenetriaminepentaacetate or sulphur colloid in a shielded syringe in a conventional manner is dispensed into nebulizer 82. Then the manifold 88 connected to cover shield 30 and the filter 90 and associated tubing are positioned above nebulizer 82 and inserted in the contour formed by inner wall 34 onto support surface 33. By pushing downwardly on cover shield 30, which is connected to manifold 88, connector 116 of manifold 88 is forced into the upper end of nebulizer 82 and groove 118 and ring 83 engage to secure the nebulizer 82 to manifold 88. The patient tubing 94 can than be attached to end 106 of manifold 88, unless it was attached beforehand. After connection of fluid delivery tube 86 to a source of driving fluid for nebulizer 82, the inhalation process can proceed in a conventional manner. As the patient inhales, the patient breathes radiolabeled aerosol generated from nebulizer 82. In the event the fluid flow volume is insufficient to satisfy the inhalation volume requirement of the patient, additional air will be brought in from the atmosphere through filter extension 92, filter 90, valve 112 and through inlet conduit 100. In that manner the patient does not feel uncomfortable if the aerosol flow volume is too low to satisfy his demands. When the patient exhales, the expired gases pass through valve 114 and outlet conduit 102 where any radioactive substance is collected by filter 90. At the end of the procedure, the flow of drive fluid to the nebulizer is ended and the patient is removed from the unit . At that time the filter, manifold 88 and nebulizer 82 can be removed from the container 20 as a unit for immediate disposal or, as has been described previously, handles 26 can be pivoted upwardly to latch to lid 22 and close the end openings through which the fluid transport system communicated with the atmosphere and the patient. While the invention has been described with reference to the specific embodiments thereof, it should be understood by those skilled in the art that various changes can be made and equivalents may be substituted therefore without departing from the true spirit and scope of the invention. All such modifications are intended to be within the scope of the claims appended hereto.
	abstract	A portable apparatus for borating a continuous flow of water includes metering assemblies provided with corresponding grinders and feeders; a feeder for supplying water to the circuit; a meter and/or flow regulator for adapting the concentration of the products supplied to the water; a pumping arrangement for conveying the mixture to a mixing reactor; a reactor with a mechanical mixer; a recirculation line of the mixer; and a supply pumping arrangement, preferably forming two units in independent cages or containers, including a crane arrangement for supplying the boration products in big bags.
	summary
044366779	description	In FIG. 1, a nitrate solution containing uranium and/or plutonium and an ammonia generating liquid are admitted into precipitation vessel 1 which contains a hot non-solvent such as trichloroethylene or silicone oil, which results in the precipitation of ammonium uranyl tricarbonate (AUT). The AUT is filtered and dried in drier 2 and is sent to calciner 3 where steam, hydrogen and nitrogen are added to calcine the AUT to uranium dioxide or plutonium dioxide. In a parallel procedure, UF.sub.6 or uranyl nitrate is admitted to second precipitation vessel 4 where ammonia, carbon dioxide, and water are added to precipitate AUT. The AUT is filtered and dried in drier 5 and is sent to calciner 6 where water, hydrogen, and nitrogen are added to effect the calcination. The resulting fertile uranium dioxide is mixed with the fissile uranium plutonium dioxide in mixer 7. As the powders are mixed they are fed into containers 8. Referring now to FIG. 2, containers 8 consist of a body portion 9 and a neck portion 10 and are filled by means of a tube 11. Once the tube has been filled, a plug 12 is inserted in the neck and the container is heat-shrunk around the plug by means of laser 13. Referring again to FIG. 1, the filled containers pass on conveyor 14 to a rotating isostatic press 15 where they are heated and isostatically pressed. The containers then pass on conveyor 16 to furnace 17 which decomposes the container and sinters the pellets. Conveyor 16 then takes the pellets to grinder 18 which polishes the pellets to the correct tolerance. A fissile powder is a powder which contains a preponderance (i.e. greater than 1%) of fissionable isotopes, and a fertile powder is a powder which contains a preponderance of isotope which can become fissionable in the presence of fast neutrons. Fissile material, for example, includes .sup.235 UO.sub.2 and PuO.sub.2 and fertile material includes .sup.238 UO.sub.2 and ThO.sub.2. In the plutonium cycle the fissile material is a mixture of .sup.235 UO.sub.2 and PuO.sub.2 and the fertile material is .sup.238 UO.sub.2. In the thorium cycle the fissile material is .sup.233 UO.sub.2 or .sup.235 UO.sub.2 and the fertile material is ThO.sub.2. The materials may or may not be the result of reprocessing. The fertile and fissile powders are preferably "free-flowing," which means having an angle of repose of less than about 45.degree.. Free-flowing powders can be prepared in a variety of ways known to the art. For example, the precipitation of ammonium uranyl tricarbonate (AUT) by the addition of ammonia and carbon dioxide-generating compounds to a nitrate solution of the fissile or fertile material, followed by collection of the precipitate, washing, drying, and calcining at about 500.degree. to about 900.degree. C. for about 1 to 5 hours in a hydrogen/steam mixture, generally results in the production of a free-flowing powder. Roll blending, a process where a binder is added to the powders and the mixture is spun in a low speed centrifuge, also may be used to produce a free-flowing powder. The preferred technique for producing free-flowing powders, however, is the sol gel technique because that technique produces a more spherical particle which is more free-flowing. In the sol gel technique an ammonia-containing compound, such as urea or hexamethylene tetramine is added to the nitrate solution and the mixture is added drop-wise into a hot non-solvent such as trichloroethylene or silicone oil, which results in the precipitation of ADU. The precipitate is collected, washed, dried, and calcined to produce the free-flowing powder. In the second step of the process of this invention the free-flowing fertile and fissile powders are mixed together. The proportion of fertile powder to fissile powder depends upon the degree of enrichment of the particular two powders being mixed and the degree of enrichment in the desired product. Generally speaking, for making pellets for use in fast breeder reactors, the mixture should contain about 20 to about 25% by weight fissile powder, and for making pellets for use in light water reactors, the mixture should contain about 1 to about 5% by weight fissile powder. To avoid separation of the powders after mixing, only so much powder as is necessary to maintain a flow of mixed powder into the containers should be mixed at any one time. In the third step of the process of this invention, the mixed powder is placed in containers from which the pellets are to be formed. The containers are small bottles made of a heat-shrinkable material such as highly cross-linked polyethylene. The dimensions of the bottle are selected according to the desired size of the resulting pellet, allowing for the shrinkage during pressing and sintering. For a typical 1/4-inch pellet for use in a fast breeder reactor, for example, the container might have an inside diameter of about 3/8-inch and be about 3/4-inch long. For making a 3/8-inch pellet for use in light water reactors, for example, the container might require an inside diameter of about 9/16-inch and be several inches long. Because the process of this invention produces a more homogeneously pressed pellet which is less subject to fracture, it is expected that pellets produced according to the process of this invention can be made considerably longer than pellets produced from previous processes. The container must also be sufficiently thick to be self-supporting. Each container may have an identifying mark embossed on its inner surface which will leave a corresponding mark on the resulting pellet for identification. If it is desired to produce cored pellets, that is, pellets with fissile material surrounding a core of fertile material, (or vice versa), a previously prepared core of fertile material is inserted into the container prior to filling the remainder of the container with the fissile powder. If cored pellets are prepared it may be necessary to alter the configuration of the container so as to support the core while the container is being filled with fissile powder. Cored pellets are believed to be more efficient in operation and offer the additional advantage that the fertile core, which is not highly radioactive, can be prepared outside the canyon using fewer safety precautions. In the fourth step of the process of this invention, the containers are sealed. Sealing can be accomplished in a variety of ways including crimping the neck of the container or inserting a plug into the neck of the container. The preferred method of sealing the container is to insert a plug of un-crosslinked polyethylene into its neck. The neck is then heated which results in the neck shrinking against the plug, forming a seal. In the fifth step of the process of this invention it is necessary to simultaneously heat the filled, sealed container and isostatically press it so as to cause the container to shrink at about the same rate that the powder contained within it is compressed. The temperature required will depend upon the particular material of which the container is made. Highly cross-linked polyethylene will shrink at a temperature of about 100.degree. to 150.degree. C. Isostatic pressing is done in a hot fluid. A liquid metal is preferred for this purpose, as metals have lower vapor pressures than do non-metallic liquids, but non-metallic liquids such as silicone oil, could also be used. Woods metal is particularly preferred due to its low melting point and low vapor pressure. Typically, about 30,000 to about 60,000 pounds per square inch will be necessary to reduce the volume of the powder by about 40 to about 60%. Heating and isostatic pressing may be done with individual containers or with a large batch of many containers at once. Pressing is preferably "wet-bag" (i.e. no permanent extra container in the press) as opposed to "dry-bag" as it is more efficient. In the sixth step of the process of this invention the containers are decomposed and the pressed powder within them is sintered to form the pellets. Decomposition of the container and sintering of the powder can be performed as two separate steps, or decomposition can be part of the sintering process. The temperature required for decomposition will depend upon the particular material from which the container is made. Cross-linked polyethylene requires a temperature of about 300.degree. C. for decomposition. During sintering, the bulk volume occupied by the compressed powder typically decreases by another 40 to 60%. The density is increased to about 95% of theoretical for light water reactors and to about 88 to about 92% of theoretical for breeder reactors. The final density obtained can be controlled by adding pore formers to the powders and by the amount of pressure used in the isostatic pressing step. While sintering is normally performed at about 1700.degree. to about 1800.degree. C., the sintering temperature can be reduced to about 1100.degree. to about 1400.degree. C., which saves energy, by performing the sintering at a higher partial pressure of oxygen than is normally used during hydrogen sintering of fuel pellets. This is a preferred procedure as it reduces the energy requirement of the process. If oxygen is used it is necessary to reduce the oxidized UO.sub.2 produced (i.e. UO.sub.2+x) with hydrogen at about the same temperature in order to reform UO.sub.2. Typically about 2 to about 5 hours are required for sintering and about 1 hour is required for reduction. While it is expected that pellets produced according to the process of this invention will be dimensionally more precise than pellets produced according to prior processes, it may nevertheless be necessary to perform a light grinding step if the pellets exceed required tolerances. The following example further illustrates the process of this invention. EXAMPLE A 1/4-inch diameter rubber balloon 6 inches long was filled with alumina powder until the diameter of the balloon was about 5/8-inch. The filled balloon was pressed isostatically in water at 30,000 psi which reduced its diameter to about 3/8-inch. The surface of the alumina was smooth and wrinkle free. The balloon adhered to the surface of the alumina and there were no holes in the balloon. This experiment demonstrates the feasibility of the process of this invention.
043226221	summary	BACKGROUND OF THE INVENTION The present invention relates to an achromatic magnetic deflection device for deflecting by an angle .phi. a beam of charged accelerated particles (electrons for example), these particles being able to present a large range of moments of quantities of movement. The deflection device of the invention enables in particular a beam of electrons accelerated between 10 and 20 Mev for example to be deflected by an angle .phi.>.pi., without having to modify the values of the magnetic fields created in the air gaps of the pole pieces forming part of the deflection device. SUMMARY OF THE INVENTION It is an object of the invention to provide a device for the achromatic magnetic deflection of a beam of accelerated charged particles comprising at least one electromagnet having pole pieces delimiting air gaps in which are created magnetic fields having the same direction and specific values so that the paths of the particles have the form of loops whose lengths depend on the momentum of the particles, these pole pieces delimiting a first, a second and a third magnetic sector disposed one after the other and joined together, the whole of these magnetic sectors having a plane of symmetry perpendicular to the plane of the mean path of the beam of particles and intersecting this plane along an axis XX, the magnetic deflection device presenting successively to the beam of particles a flat input face, a first curved face, a second curved face and a flat output face, the input and output flat faces forming therebetween an angle 2.alpha., the first and second curved faces, as well as the axis of symmetry XX, being substantially orthogonal to the different paths of the particles, the values of the magnetic inductions created in the first and third magnetic sectors being respectively equal to KB.sub.o, B.sub.o being the value of the magnetic induction in the second magnetic sector and K a numeric coefficient less than 1. The above and other objects, features and advantages of the present invention will become apparent from the following description, given solely by way of non-limiting illustration, when taken in conjunction with the accompanying drawings.
047675942	description	SUMMARY OF THE PRIOR ART Referring to FIG. 1A, a liquid sodium reactor is shown enclosed within a containment vessel C and a reactor vessel V. As is common in the art, containment vessel C is closely spaced to reactor vessel V and is capable of containing liquid sodium S in case of a rupture of the reactor vessel V. The components of the reactor can best be understood by tracing the sodium coolant flow path and at the same time describing the component parts. Continuing with FIG. 1A and remembering that the reactor is undergoing normal power operation, core 12 heats passing sodium S and discharges the sodium S into a hot pool 14. Hot pool 14 is confined interior of the reactor by a vessel liner L. It is important to note that vessel liner L only extends partially the full height of the reactor vessel V terminating short of the top of the reactor vessel V at 16. Sodium from hot pool 14 enters into intermediate heat exchanger H and dissipates heat. Heat is dissipated through a secondary sodium circuit schematically labeled 18 which passes typically to a steam generating heat exchanger and then to conventional power generation (both these elements not being shown). After heat exchange and flow induced pressure drop across heat exchanger H, the liquid sodium passes to cold pool 20. Cold pool 20 is at a lower hydrostatic pressure than hot pool 14 because of the pressure drop through the heat exchanger H. Cold pool 20 outflows through fixed shield cylinders 22 to the inlet 24 of main reactor pumps P. Typically main reactor pumps P are of the electromagnetic variety and have low pressure inlet 24 and high pressure outlet 26. Sodium outlet through high pressure outlet 26 passes through pump discharge pipe 28 to the inlet of core 12. This completes the sodium circuit. The reactor cold pool 20 is maintained at a slightly lower pressure (about 4 psi) from the reactor hot pool during normal operation. The necessary reactor control rods enter and are withdrawn to and from a control rod plenum 30. Since the control rods do not constitute a part of this invention, they will not further be discussed. The reader will realize that FIG. lA and its description is an oversimplification of the sodium cooled roactor. In actual practice, the reactor includes two kidney sectioned heat exchangers H and four pumps P. Disposition of the pumps P and heat exchangers H can be understood with respect to FIG. 1B. It will further be understood that the section of FIG. 1A is for purposes of understanding. Observing 1A--1A. Not section lines shown on FIG. 1B. I have indicated where they might be section lines 1A--1A on FIG. 1B, it will be seen that the section is not conventional. Referring to FIG. 1C, the prior art reactor vessel auxiliary cooling system sodium flow loop can be understood. First, and upon occurrence of a casualty involving loss of all normal heat removed paths via the IHX H and the secondary sodium circuit 18 it is assumed that all electrical pump power is lost. Since all electrical power is lost, pumps P will become inoperative. When loss of pump coolant pressure has occurred, control rods from plenum 30 will be fully inserted within core 12. Initially, and for a period of several hours, residual heat within core 12 will cause a primary sodium flow circuit identical to that illustrated in FIG. 1A. However, the natural circulation primary sodium flow rate, with the loss of pressure of pumps P will be 2% or 3% of the normal flow rate. In about two or three hours, a reactor will undergo a thermal transient. It will heat from a normal hot pool temperature of around 875.degree. F. to approximately 1000.degree. F. in both the hot pool and the cold pool. This heating occurs because even with the control rods fully inserted as residual heat from the atomic reaction needs to be dissipated from core 12. The fluid circuit of FIG. 1A without the pumps operational is marginal for the required dissipation of the reactor residual heat in the long term. As the sodium temperature increases, the sodium expands. It expands from the relatively low level illustrated in FIG. 1A to the relatively high level illustrated in FIG. 1C. In fact, the sodium level expands upwardly and over top wall 16 of reactor vessel liner L. It is at this point that a new (but prior art) flow circuit providing the necessary dissipation of heat is provided. Referring to FIG. 1C, flow occurs from reactor cold pool 20 through pump inlet manifold 24 through pump P to outlet manifold 26 and pump discharge pipe 28. The sodium passes through core 12 into hot pool 14. At hot pool 14, some sodium will flow through intermediate heat exchanger H. The large measure of sodium flow will occur over the top of vessel liner L at 16 and into the vessel liner flow gap G. Remembering that vessel flow liner gap G extends entirely around the periphery of the reactor vessel V, it can be seen that hot sodium is provided with an improved heat discharge path. As the exterior of the containment vessel C is continually cooled with passing air, it will be understood that the prior art flow circuit of FIG. 1C provides the necessary improved dissipation of residual heat from the shutdown reactor. In the nuclear industry, there remains a constant search for improved safety margins. It is necessary in the understanding of my invention to review the safety considerations of the prior art reactor circuit just set forth. It will be realized that the flow circuit illustrated in FIG. 1C is volume dependent on the amount of sodium contained within the reactor vessel V. If the volume is less than that illustrated in FIG. 1A, the reactor will be required to undergo a greater heatup transient to provide for the necessary expansion of the sodium S to achieve the required liner overflow. The interior of the reactor vessel V is an extremely hostile environment. Sodium level gauges have been and are now always suspect in their operation. In an volume dependent sodium system, the malfunction of a level gauge could well lead to the reactor undergoing higher temperature transients than those transients originally intended to cause the flow circuit of FIG. 1C. Further, and assuming that there is a rupture in the vessel V to the containment vessel C, the level of the sodium would drop and the flow circuit of FIG. 1C would not be established without a greater temperature transient, if establishment occurred at all. Simply stated, the flow circuit of FIG. 1C has demonstrable disadvantages known to those skilled in the art. DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 2A, the improvement of my invention is illustrated. Simply stated, I installed across reactor vessel liner L, a jet pump 40. Jet pump 40 has an inlet 42 at the reactor vessel liner flow gap G, a venturi 44 and an outlet 46. Outlet 46 is typically within, parallel to, and well below the surface of the sodium pool to provide surging of the liquid sodium at the top of the pool during normal reactor operation. Jet pump 40 is powered during normal reactor operation through a high pressure sodium line 48. Sodium line 48 has an inlet 49 at the high pressure plenum 26 of pump P and a high velocity outlet 50 into the venturi 44. With a flow of pumping fluid from the high pressure plenum 26 into the venturi 44, jet pump 40 will entrain a flow of fluid. This flow of fluid will be from the cold pool through the reactor vessel liner flow gap G into the hot pool 14. As illustrated in FIG. 2A, together with the flow across the intermediate heat exchanger H, the jet pump 40 of FIG. 2A will assist in establishing the required pressure differential between the cold pool in reactor vessel liner flow gap G and the hot pool 14. It will be understood that in FIG. 2A, I only illustrate one jet pump 40. In actual practice I currently contemplate eight such jet pumps 40 with two such pumps being communicated to each pump P. It will be understood that the number of pumps 40 and their placement will constitute an optimization process which will be dependent upon the flow thermodynamics of any particular sodium reactor. Referring to FIG. 2B, the operation of my pump 40 upon loss of high pressure within pump P high pressure plenum 26 can be readily understood. As indicated earlier loss of high pressure within pump P would occur following loss of the normal heat removal paths and rapid activation of the overflow path is required. First, jet pump 40 will no longer function. Second, liquid sodium from reactor hot pool 14 will immediately backflow through jet pump outlet 46 into the reactor vessel liner flow gap G at jet pump inlet 42 In short, jet pump 40 will operate as a nonmechanical check valve allowing the immediate establishment of a flow circuit from the reactor vessel hot pool 14 into the reactor vessel liner flow gap G. ADVANTAGES The reader will understand that by the establishment of an immediate flow circuit from the reactor hot pool to the reactor vessel liner flow gap G that an a headup transient of the reactor for the required sodium expansion is no longer necessary. Instead, and upon pump P shutdown, the supplementary cooling circuit is immediately established. Thus, my invention constitutes an improved reactor design. This improved design includes not having to depend on the heatup transient necessary for activating the cooling circuit of the prior art illustrated in FIG. 1C. Additionally, my cooling circuit is no longer as volume dependent upon the level of liquid sodium S required in a reactor. So long as the sodium level is above the outlet 46 of jet pump 40, my system is functional. The advantage of this can be understood especially where rupture of the reactor vessel occurs and overflow to the containment vessel is present. Where such overflow occurs, there will be a drop in the level of sodium S. This drop in the level of sodium S will not affect the operation of my cooling circuit nor its immediate establishment. Further, the cooling circuit of my invention is less dependent upon the accuracy of sodium level gauges in the internal of reactor vessel V. There is a price for the safety feature of my system. It will be understood that I dilute reactor hot pool 14 by small direct flow from the reactor vessel cold pool through the vessel liner flow gap G. Additionally, I use energy of pump P for my jet pumps 40. Accordingly, the pumps and heat exchangers must be expanded in size to accommodate an approximate 15% increase in overall system flow rate. Further, the hot pool temperature will decline. However, the overall output of the reactor will remain substantially unchanged. By way of example, in a 400 megawatt reactor approximately 4 megawatts will be utilized in pumping. According to the prior art embodiment of FIG. 1C, the safety circuit of my invention will require 4.6 megawatts for the required pumping. It is submitted that these required changes in heat exchanger and pump capacity are more than compensated by the improved safety set forth.
050846256	summary	BACKGROUND OF THE INVENTION The present invention relates to the field of transporting hazardous materials, especially radioactive materials, to an apparatus for measuring and testing, especially an apparatus for differential thermal analysis. Radioactive materials are often handled in a containment area such as a glovebox. However, apparatus for analyzing radioactive materials is often located outside of the containment area. For example, a sample of radioactive material may be taken in a glovebox for analysis in a differential thermal analyzer located outside the glovebox. More specifically, a standard commercial differential thermal analysis (DTA) apparatus would be extremely difficult, if not impossible, to operate inside a glovebox due to the fact that the DTA apparatus components are extremely fragile. Moreover, milligram quantities of the sample material must be handled with a precision that is extremely difficult and time consuming to perform within the confines of a containment device such as a glovebox. Furthermore, proper maintenance of a DTA apparatus would be difficult inside a glovebox. In addition, a furnace for DTA may routinely operate at 1,000 degrees Centigrade, thereby making it economically unfeasible to adequately cool the glovebox to within current specifications for proper fire prevention. In analyzing a radioactive sample in an apparatus outside a glovebox, it is desirable that the radioactive sample does not come into contact with either personnel or the environment outside the analytical apparatus. More specifically it is desirable that a radioactive sample remain untouched by personnel and isolated from the environment as the sample is taken, as the sample is loaded into a sample transporter in a glovebox, as the sample is transported to an analytical apparatus, as the sample is analyzed and as the analyzed sample is returned to the glovebox. SUMMARY OF THE INVENTION Accordingly it is an object of the present invention to provide a transporting apparatus for a radioactive sample whereby the sample remains untouched after the sample is taken and loaded into the sample transporter in a glovebox, as the sample is transported to an analytical apparatus, as the sample is analyzed, and as the analyzed sample is returned to the glovebox. Another object of the invention is to provide an apparatus that effectively contains radioactive samples that are accidentally dropped when being transported from a glovebox to a measuring or testing apparatus. Another object is to provide a sample transporter for crucibles used in a DTA apparatus wherein the transporter accommodates different crucible sizes that are utilized by various DTA equipment. Additional objects, advantages, and novel features of the invention will be set forth in part in the description that follows and in part will become apparent to those skilled in the art upon examination of the following or may be learned with the practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims. To achieve the foregoing and other objects, and in accordance with the purposes of the present invention as described herein, an improved apparatus and method are provided for selectively receiving, transporting, and releasing a hazardous sample for analysis on an analytical apparatus. The subject apparatus includes a portable storage member for storing and transporting the sample. The storage member includes a top side and a bottom side. An adjustable top door is located on the top side of the storage member, and the top door permits the sample to enter the storage member through the top side when the top door is in an open position. The top door isolates the sample within the storage member when the top door is in a closed position. An adjustable bottom door is located on the bottom side of the storage member. The bottom door isolates the sample in the storage member when the bottom door is in the closed position and the bottom door permits the sample to leave the storage member through the bottom side when the bottom door is in the open position. More specifically, the storage member includes a plurality of storage chambers arrayed circumferentially with respect to a central axis. An adjustable top door is located on the top side of the storage member, and the top door includes a channel capable of being selectively placed in registration with the respective storage chambers thereby permitting the samples to selectively enter the respective storage chambers through the top side when the top door is in an open position. The top door isolates the respective samples within the storage chambers by placing the top door channel out of registration with the respective storage chambers when the top door is in a closed position. In addition, a plurality of adjustable bottom doors are located on the bottom sides of the respective storage chambers. The bottom doors isolate the samples in the respective storage chambers when the bottom doors are respectively in the closed position. The bottom doors permit the samples to leave the respective storage chambers from the bottom side when the respective bottom doors are in respective open positions. The bottom doors are supported by a base member that is located below and supports the storage member. Preferably, the bottom doors include springs for biasing the doors in the closed position. The bottom doors also include actuator means for engaging a hand-held implement for opening the doors. The apparatus of the invention can be especially adapted for use with a DTA apparatus. In this respect, the apparatus further includes a channel for receiving a sparge tube of the DTA apparatus. For use with a DTA apparatus, the apparatus of the invention further includes a support for supporting the sample transporter so that the sample transporter is properly positioned with respect to the sample receiving portion of the DTA apparatus. To facilitate alignment of the sample transporter with the DTA apparatus, a lock is provided to lock the two elements together. In accordance with another aspect of the invention, a method of handling hazardous analytical samples is provided. In the method, a plurality of sample containers are first loaded into a plurality of storage chambers of a portable transporter in a containment area. The transporter serves to isolate the sample containers from the environment. The transporter containing the sample containers are then transported to an analytical apparatus, such as a DTA apparatus. The transporter is placed in close proximity to a sample receiving portion of the analytical apparatus, such that a sample container is permitted to move directly from a storage chamber in the transporter to the receiving portion of the analytical apparatus. The transporter is then moved away from the analytical apparatus. After an analysis is performed, the transporter is once again placed in close proximity to the sample receiving portion of the analytical apparatus. The sample container is then moved from the analytical apparatus directly into a storage chamber in the transporter, and the sample container is isolated from the environment by being in the storage chamber.
	claims	1. A linear accelerator head comprising:an electron generator configured to emit electrons along a beam path;a microwave generation assembly comprising:a microwave generator configured to emit microwaves in a first direction along a primary wave path; andan isolator configured to prevent microwaves from propagating in a second direction opposite the first direction along the primary wave path;a waveguide configured to contain a standing or travelling microwave and accelerate electrons to between about 3 MeV and about 9 MeV, the waveguide comprising a plurality of cells each defining an aperture configured to receive electrons therethrough; anda converter disposed within the electron beam path and configured to receive incident electrons and convert the incident electrons into photons, the converter including a disc comprising:a first layer of a first material; anda second layer of a second material. 2. The linear accelerator head of claim 1, wherein the first material comprises a chemical element having an atomic number greater than about 57. 3. The linear accelerator head of claim 1, wherein the second material comprises a chemical element having an atomic number greater than about 57. 4. The linear accelerator head of claim 1, wherein the first material comprises tungsten. 5. The linear accelerator head of claim 1, wherein the second material comprises aluminum. 6. The linear accelerator head of claim 1, wherein the second material comprises copper. 7. The linear accelerator head of claim 1, wherein the disc has a thickness of between about 1 mm and 8 mm. 8. The linear accelerator head of claim 1, wherein the first layer has a thickness of between about 0.5 mm and 4 mm. 9. The linear accelerator head of claim 1, wherein the second layer has a thickness of between about 0.5 mm and 4 mm. 10. A linear accelerator head comprising:an electron generator configured to emit electrons along a beam path;a microwave generation assembly comprising:a microwave generator configured to emit microwaves in a first direction along a primary wave path; andan isolator configured to prevent microwaves from propagating in a second direction opposite the first direction along the primary wave path;a waveguide configured to contain a standing or travelling microwave and accelerate electrons to between about 3 MeV and about 9 MeV, the waveguide comprising a plurality of cells, each of the plurality of cells defining an aperture having a diameter and configured to receive electrons therethrough, the apertures of the cells defining a beam axis of the waveguide along the beam path;a cooling system in thermal communication with the waveguide, the cooling system comprising a block having a channel configured to guide fluid therethrough; anda converter disposed within the electron beam path, the converter configured to receive incident electrons and convert the incident electrons into photons. 11. The linear accelerator head of claim 10, wherein the waveguide comprises a first exterior surface parallel to the beam axis. 12. The linear accelerator head of claim 11, wherein the waveguide comprises a second exterior surface parallel to the first exterior surface. 13. The linear accelerator head of claim 12, wherein the block defines a surface coplanar with the first exterior surface of the waveguide. 14. The linear accelerator head of claim 10, wherein the block comprises an opening configured to allow a user access to at least one of the tuners of the plurality of cells. 15. A linear accelerator head comprising:an electron generator configured to emit electrons along a beam path;a microwave generation assembly comprising:a magnetron configured to emit microwaves in a first direction along a primary wave path; andan isolator configured to prevent microwaves from propagating in a second direction opposite the first direction along the primary wave path;a waveguide configured to contain a standing or travelling microwave and accelerate electrons to between about 3 MeV and about 9 MeV, the waveguide comprising a plurality of cells each defining an aperture configured to receive electrons therethrough; anda converter disposed within the electron beam path, the converter configured to receive incident electrons and convert the incident electrons into photons. 16. The linear accelerator head of claim 15, wherein the magnetron is configured to emit microwaves at a frequency in a range of between about 7.0 GHz and 11.2 GHz. 17. The linear accelerator head of claim 15, wherein the magnetron is configured to emit microwaves at a power greater than 1 MW. 18. The linear accelerator head of claim 15, configured to deliver between about 300 cGy/min and 1800 cGy/min. 19. The linear accelerator head of claim 15, wherein the waveguide further comprises a coupler cell configured to couple microwaves from the isolator into the waveguide and to provide fluid communication between a vacuum pump and an interior of the waveguide. 20. The linear accelerator head of claim 15, wherein the plurality of cells comprises fewer than 24 cells.
	summary
050777742	claims	1. An apparatus for generating high-intensity X rays for lithography using a mask to define against areas on a wafer for the production of integrated circuits comprising: electron-beam-source means for generating an electron beam; X-ray means comprising a foil stack for integrating electrons from said electron-beam-source means for generating a beam of soft X rays from transition radiation, said X-rays having a conical power density, hereinafter called the conical X-ray annulus; radiation uniformity means for achieving X-ray power uniformity across the mask and wafer target areas with an intensity variation of .+-.5% or less; magnetic means for separating the electron beam from the X-ray beam; housing means for providing an optical medium for the apparatus, and a controlled environment for said X-ray means and said radiation uniformity means. electron beam source means for generating and electron beam; a plurality of X-ray means for generating soft X rays from transition radiation, at least one of said X-ray means comprising a foil stack; said X-rays having a conical power density, hereinafter called the conical X-ray annulus; a plurality of radiation uniformity means for achieving X-ray uniformity across the mask and wafer target areas with an intensity variation of .+-.5% or less; a plurality of magnetic means for separating the electron beam from the X-ray beam; a housing means for providing an optical medium for the apparatus, and a controlled environment for said X-ray means, and said radiation uniformity means. such that the outer radius, r, of the area of said conical X-ray annulus at the mask/wafer is given approximately by: ##EQU37## where Z.sub.0 is the distance between the foil stack and the mask/wafer target, where E is the electron beam energy, E.sub.0 is the electron beam rest energy (E.sub.0 .perspectiveto.0.511 MeV), such that the conical X-ray annulus area matches or is smaller than the desired exposure area of said mask/wafer target, and such that there is adequate distance Z.sub.0, between said foil stack and mask/wafer target (Z.sub.0 is approximately 1 to 3 meters) for radiation shielding and electron-beam transport. such that said electron-beam diameter, D is bounded by: ##EQU38## where g is the distance between the mask and wafer, Z.sub.0 is the distance between foil stack and the mask/wafer target, and .DELTA.x is the blurring or shadowing of the minimum circuit feature size, x; such that said electron beam divergence is bounded by; ##EQU39## where .DELTA.g is the maximum variation in mask-to-wafer distance and is bonded by: EQU .DELTA.g.ltoreq.5 .mu.m where .DELTA.R is the error introduced to the minimum circuit feature size, x, by the source divergence, and E.sub.0 is the electron rest energy (E.sub.0 =0.511 MeV); where .DELTA.x and .DELTA.R are bounded by: EQU (.DELTA.x.sup.2 +.DELTA.R.sup.2).sup.1/2 .ltoreq.0.3x X-ray optic means for the efficient collection of X rays and the transporation of the X rays to the mask/wafer target area. number of foils, M, arranged as a succession of parallel elements to form said stack, the foils having a minimum thickness l.sub.2 ; holding means for holding the foils in said stack and for maintaining a spacing l.sub.1 between adjacent foils in said stack; a plurality of foil stacks spaced such that the conical X-ray annulus generated from each foil stack misses the succeeding foil stacks such that said annuli wall add in concentric rings at the mask target areas; holding means for the foil stack such that said holding means does not interfere with the transmission of the X rays to mask target areas, wherein the radius, r.sub.0, of the foil stack and its holding means should not be less than: ##EQU44## where L is the distance between the foil stacks, E is the electron beam E, E.sub.0 is the rest energy of an electron (E.sub.0 .perspectiveto.0.511 MeV). a series of foil stacks; magnetic means for changing the electron-beam direction at each foil stack, where such magnetic means is composed of dipole magnets, where two pairs of said dipole magnets are located between each succeeding foil stack, where the magnetic fields of said two pairs of dipoles are of opposite polarity, where each magnetic field of said pair of dipole magnets are adjusted such the angle of the electron beam is directed such that the conical X-ray annulus generated from each foil stack miss succeeding foil stacks and add concentrically at the mask/wafer target areas, where the angle of electrons leaving the n'th foil stack (and hence the direction of the conical X-ray annulus) is determined approximately by: ##EQU45## and ##EQU46## where E is the electron beam energy, E.sub.0 is the electron beam rest energy (E.sub.0 .perspectiveto.0.511 MeV), L.sub.n is the distance between the n and n+1 foil stacks, and Z.sub.0 is the distance between the last foil stack and the mask/wafer target, Y is the distance from the axis of the foil stack and the center of the mask/wafer target, d.sub.n+1 is the diameter of the n+1 foil stack and foil stack holding means. where said electron-beam direction means is composed of plurality of dipole magnets, where said dipole magnets are located between the electron-beam means and the foil stack, where said dipole magnets magnetic field is adjusted so that the electron-beam direction through the foil stack is changed, where said electron beam is held fixed at a particular location on said foil stack, such that the direction of the X rays changes but not the point of emanation, such that the time average X-ray power uniform across the mask and wafer is .+-.5% or less. where said electron optics means is composed of either a torroidal magnet or a plurality of quadrapole magnets, where said electron optic is located between said electron-beam source and said foil stack where said electron optic is adjusted such that said conical X-ray annulus is filled and such that the resulting X-rays power is uniform within .+-.5% or less across the target area of the mask. where said X-ray optics means is located between said X-ray means and said mask and wafer target, where said electron optics means is composed of either a torroidal magnet or a plurality of quadrapole magnets, where said electron optic is located between said electron-beam source and said foil stack, where said electron optic is adjusted such that said conical X-ray annulus is filled, such that the resulting X-rays power is uniform within .+-.5% or less across the mask/wafer target area. said conical X-ray annulus intersects the inner surface of said surface-of-revolution at angles less than or equal to .omega..sub.p /.omega., where .omega..sub.p is the plasma frequency of the optical medium and .omega. is the frequency of the X rays, said surface-of-revolution lens lies between said foil stack and said mask/wafer target, and said X rays are collected on to a desired area on the mask/wafer area. a longitudinal surface in the direction of the axis of revolution that is curved to make the resulting radiation pattern uniform for the uniform exposure of photoresist; a baffle to block direct X-ray paths from the foil stack to mask/wafer target area so that only reflected X-rays each the mask/wafer target area; wherein said longitudinal surface is defined by the following variables: the minimum angle in the portion distribution, .theta..sub.min (photons produced with smaller angles will be blocked by the baffle and those with larger angles will be reflected to the mask), the maximum angle in the photon distribution .theta..sub.max (Photons produced with larger angles are ignored), the diameter of the mask to be uniformly illuminated, d.sub.s, the exit diameter of the lens to be designed, d.sub.e ; where said longitudinal surface is computer using a simple computer program that computes the following, from simple geometrical considerations: distance from the source to the mask, L: ##EQU49## distance from the exit end of the lens to the mask, L.sub.1 ; ##EQU50## distance from the source to the exit end of the lens, L.sub.2 ; ##EQU51## lens radius at exit; ##EQU52## said computer program begins by assigning the starting coordinate pair (z,r) to the lens cross-section, where z=L.sub.2, and r=r.sub.e. The program further assigns the slope of the lens shape to an angle slightly larger than .theta..sub.min : ##EQU53## where .DELTA. is 1.2 of the bin width of the photon distribution, where the lowest angle photons will just graze the exit portion of the lens and continue on to the mask; said computer program next steps through positions on the mask, starting with the largest radius and computes the number of photons necessary to fill the photon deficiency where the photons must come from the flux distribution just above .theta..sub.min ; said computer program then depletes this distribution just the right amount and computes the mean angle of these photons where an X ray from the source, with this mean angle, then intercepts the lens element having a straight line pinned at (r,z) and fixed slope dr/dz, where this intercept defines the next locus of the lens cross-section where the angle formed from this new value of (r,z) to the mask, together with the source angle, define the lens angle dr/dz at this new point, where the computation then iterates until the source angle is equal to or greater than .theta..sub.max ; said computer program computes the cross-section of the lens is drawn on the display terminal, and a table is written as input for a numerically controlled lathe for the machining of the surface-of-revolution lens. where said grazing-angle reflector reflects the X-rays to the mask/wafer target, where said grazing-angle reflector separates the desired soft X-rays from the neutron flux, the hard X-ray bremmstrahlung and other ionizing radiation such that neutron flux, hard X-ray bremsstrahlung and other ionizing radiation does not strike the mask/wafer target, where said grazing-angle reflector lies between said foil stack and said mask/wafer target, where said grazing-angle reflector is composed of either a flat or slightly curved X-ray mirror whose dimensions are determined by the grazing angle, .theta., by the distance from the radiator to grazing-angle reflector, L.sub.g, and by the angular divergence of the conical X-ray annulus (.theta..perspectiveto..+-.3/.gamma.). The minimum length, l.sub.min, of optic is then given by: ##EQU54## and the minimum width, w.sub.min, of the mirror is given by: ##EQU55## where the grazing angle of said grazing angle reflector is .theta..sub.g .gtoreq..omega..sub.p /.omega..sub.c where .omega..sub.p is the plasma frequency of the surface material of said grazing angle reflector and .omega..sub.c is the desired cutoff X-ray photon energy. such that the number of X-rays whose X-ray photon energies .omega.>.omega..sub.c are attenuated, where said X-ray photon energies above .omega..sub.c penetrate both the mask substrate and the mask circuit pattern causing blurring of the circuit image, where said cutoff frequency .omega..sub.c is approximately 3 keV. means of rotating the foil stack around its central axis; motor means for supplying circular motion to the foil stack; housing means for providing an optical medium for the apparatus, and a controlled environment for said foil stack; coupling means between the motor and the foil stack, where said coupling means transfers motion of the motor to the foil stack from the environment of the motor to the environment of the foil stack. a low density gas (such as helium) in contact with the foil stack for the conduction of the heat from the foil stack; housing means for providing an optical medium for the apparatus, and a controlled environment for said foil stack, where said housing means contains the low density gas; means for the removal and/or cooling of the low density gas. a foil-stack holding means of high-heat-conductivity material such as aluminum or copper for the transfer of thermal heat in the foil stack to the foil-stack holder; housing means for providing an optical medium for the apparatus, and a controlled environment for said foil stack, where said housing means is mechanically and thermally connected to the foil-stack holding means such that the heat is transferred to the external environment outside said housing means. said conical X-ray annulus intersects the inner surface of said surface-of-revolution at angles less than or equal to .omega..sub.p /.omega., where .omega..sub.p is the plasma frequency of the optical medium and .omega. is the frequency of the X rays, said surface-of-revolution lens lies between said foil stack and said mask/wafer target, and said X rays are collected on to a desired area on the mask/wafer area. a longitudinal surface in the direction of the axis of revolution that is curved to make the resulting radiation pattern uniform for the uniform exposure of photoresist; a baffle to block direct X-ray paths from the foil stack to mask/wafer target area so that only reflected X-rays reach the mask/wafer target area; where said longitudinal surface is defined by the following variables: the minimum angle in the photon distribution, .theta..sub.min (photons produced with smaller angles will be blocked by the baffle and those with larger angles will be reflected to the mask), the maximum angle in the photon distribution, .theta..sub.max (Photons produced with larger angles are ignored), the diameter of the mask to be uniformly illuminated, d.sub.s, the exit diameter of the lens to be designed, d.sub.e ; where said longitudinal surface is computer using a simple computer program that computes the following, from simple geometrical considerations: distance from the source to the mask, L: ##EQU56## distance from the exit end of the lens to the mask, L.sub.1 : ##EQU57## distance from the source to the exit end of the lens, L.sub.2 : ##EQU58## lens radius at exit: ##EQU59## said computer program begins by assigning he starting coordinate pair (z,r) to the lens cross-section, where z=L.sub.2, and r=r.sub.3. The program further assigns the slope of the lens shape to an angle slightly larger than .theta..sub.min : ##EQU60## where .DELTA. is 1.2 of the bin width of the photon distribution, where the lowest angle photons will just graze the exit portion of the lens and continue on to the mask: said computer program next steps through positions on the mask, starting with the largest radius and computes the number of photons necessary to fill the photon deficiency where these photons must come from the flux distribution just above .theta..sub.min ; said computer program then depletes this distribution just the right amount and computes the mean angle of these photons where an X ray from the source, with this mean angle, then intercepts the lens element having a straight line pinned at (r,z) and fixed slope dr/dz, where this intercept defines the next locus of the lens cross-section where the angle formed from this new value of (r,z) to the mask, together with the source angle, define the lens angle dr/dz at this new point, where the computation then iterates until the source angle is equal to or greater than .theta..sub.max ; said computer program computes the cross-section of the lens is drawn on the display terminal, and a table is written as input for a numerically controlled lathe for the machining of the surface-to-revolution lens. 2. An apparatus for generating multiple high-intensity X-ray beams for lithography in the production of integrated circuits comprising: 3. Apparatus as in claim 1 or 2 wherein the electron-beam source has an energy, E, selected, 4. Apparatus as in claim 1 or 2 wherein the electron-beam source has an electron-beam diameter, D, at the foil stack and half-angle divergence, .theta.d, at the foil stack selected 5. An apparatus as in claim 1 or 2 further comprising: 6. An apparatus as in claim 1 or 2 wherein said X-ray means produces X-rays at an energy less than 4 keV, said X-ray means comprising: 7. Apparatus as in claim 6 wherein said foils comprise beryllium. 8. Apparatus as in claim 6 wherein said foils and said mask substrate comprises silicon. 9. Apparatus as in claim 1 or 2 wherein said X-ray means compises: 10. Apparatus as in claim 1 or 2 wherein said X-ray source means comprises: 11. Apparatus as in claim 1 or 2 wherein said radiation uniformity means comprises electron-beam directional means 12. Apparatus as in claim 1 or 2 wherein said radiation uniformity means comprises electron optic means 13. Apparatus as in claim 12 wherein said electron optic means for adjusting the electron-beam diameter, D, and electron beam divergence angle, .theta..sub.d, at the foil stack to be: ##EQU47## where g is the mask-to-wafer gap, where Z.sub.0 is the distance from the foil stack to the mask/wafer, where .DELTA.x is the maximum tolerable blurring of the minimum sized circuit feature, x, where nominally .DELTA.x<0.3 x, ##EQU48## where E is the electron beam energy, E.sub.0 is the electron beam rest energy (E.sub.0 .perspectiveto.0.511 MeV), such that the X-ray power uniformity across the mask and wafer is less than .+-.5%. 14. Apparatus as in claim 1 or 2 wherein said radiation uniformity means comprises an X-ray optics means and electron optic means, 15. Apparatus as in claim 5 wherein said X-ray optic means comprises a surface-of-revolution lens whose axis of revolution lies along the directed axis of the conical X-ray annulus, 16. Apparatus as in claim 15 wherein said surface-of-revolution lens comprises a smooth-bore tube comprising a material selected from the groups; metal, glass, or quartz. 17. Apparatus as in claim 15 wherein surface-of-revolution lens comprises: 18. Apparatus as in claim 15 wherein said surface-of-revolution lens are coated on their reflecting surfaces with thin layers of materials that increase the reflectivity of the X-rays from said surfaces. 19. Apparatus as in claim 5 wherein said X-ray optics means comprises a Fresnel Zone plate located between the transition radiator and the mask and wafer. 20. Apparatus as in claim 1 or 2 further comprising a grazing-angle reflector means, 21. Apparatus as in claim 20 further comprising scanning means for scanning or wobbling the grazing angle reflector is scanned or wobbled such that the time average X-ray power uniformity across the mask and wafer is less than .+-.5%. 22. Apparatus as in claim 1 or 2 further comprising a translating means for moving the mask/wafer target in a rapid fashion such that the time average X-ray power across the mask/wafer target area is less than .+-.5%. 23. Apparatus as in claim 1 or 2 further comprising a cooling means for maintaining the temperature of said foils at values below foil material melting temperature. 24. Apparatus as in claim 23 wherein said cooling means comprises: 25. Apparatus as in claim 23 wherein said cooling means comprises: 26. Apparatus as in claim 23 wherein said cooling means comprises: 27. Apparatus as in claim 14 wherein said X-ray optic means comprises a surface-of-revolution lens whose axis of revolution lies along the directed axis of the conical X-ray annulus, 28. Apparatus as in claim 27 wherein said surface-to-revolution lens comprises a smooth-bore tube comprising a material selected from the groups; metal, glass, or quartz. 29. Apparatus as in claim 27 wherein surface-of-revolution lens comprises: 30. Apparatus as in claim 27 wherein said surface-of revolution lens are coated on their reflecting surfaces with thin layers of materials that increase the reflectivity of the X-rays from said surfaces. 31. Apparatus as in claim 14 wherein said X-ray optics means comprises a Fresnel Zone plate located between the transition radiator and the mask and wafer.
040615359	abstract	An illustrative embodiment of the invention provides pressure relief valve means for the core support cylinder of a nuclear reactor vessel during a failure or accident of the nuclear reactor system. The valve means is responsive to differential pressure across the valve which in one direction sealably seats the valve plate against the valve body, and which, in the other direction opens the valve for pressure relief of the cylinder. Moreover, the valve means is provided with energy absorbing means which limit the impact load of an "explosively" opening valve on the reactor vessel wall.
	description	The present invention relates to the field of radioactive material transport and storage. It relates more particularly to the transport/storage in a horizontal position of a package intended to contain radioactive materials. A radioactive material transporting/storing package has usually a side body, a bottom and a lid. These package parts define a cavity for housing radioactive materials, for example fresh or spent nuclear fuel assemblies, or waste cases. Moreover, a basket can be arranged within the housing cavity to define compartments in which the different cases/assemblies are placed. For storing the package on different sites and/or transporting it between these sites, the package is placed on a supporting device, on which it rests in a horizontal position. The supporting device forms an entity on its own, or is integrated to a road or railway transport system. In any case, this supporting device is designed to fulfil the mechanical support function for the package in a horizontal position, whereas the cooling function is ensured by the outer surface of the package that forms an exchange surface. In the case of a strong power, this exchange surface can besides be increased using fins arranged at the periphery of the side body of this package. With or without fins, a strong spatial heterogeneity in the temperatures can be found, both due to an enhancement in the thermal load downwardly because of the contact of the basket on the inner surface of the cavity, but also to a lesser efficiency of the natural convection in the bottom part of the package, where the air is yet insufficiently accelerated. Thus, even in the presence of the cooling fins, the bottom part of the package makes up a particularly hot zone when the same rests horizontally on the supporting device, the temperature distribution being not homogeneous all around the side body of the package. Heat dissipation may not be sufficiently efficient in this hot zone, because the ambient air has difficulties in coming as closely as possible to this zone. This problem is also found when the side body is not covered with cooling fins. To limit the extent of this hot zone of the package as well as its temperature, it can be contemplated to add cooling fins or to improve the efficiency thereof. However, that requires high development and set-up costs. Another solution consists in decreasing the thermal power which is allowed within the package, such that the hot zone generated meets the qualification criteria for sensitive materials making up the package, as the neutron absorbing resin. However, the decrease in the thermal power which is allowed inevitably results in decreasing the amount of radioactive materials transportable by the package, which negatively impacts the operation requirements. Thus, the purpose of the invention is to overcome at least partially the abovementioned drawbacks, relating to embodiments of prior art. To that end, one object of the invention is a supporting device for supporting a radioactive material transporting/storing package in a horizontal position, the supporting device comprising a structural base as well as supporting means for supporting the package which are carried by said structural base from which they upwardly project. According to the invention, the supporting device further comprises, being located at least partly above the structural base, a cooling air guide shroud of the package by natural convection, said shroud defining an upwardly open cavity in which a part of the package is intended to be housed when this package is supported in a horizontal position on the device, said shroud comprising, in a bottom part thereof, at least one aperture for taking in cooling air in said cavity. Advantageously, the shroud specific to the invention enables the storage cooling in a horizontal position, at its bottom part, to be improved, by virtue of a natural convection effect. The invention thus is a solution enabling the hot zone at the bottom part of the package to be reduced or even removed, at a lesser cost without lowering the thermal power which is allowed. Moreover, the fact that the shroud is integrated to the device for supporting device the transport/storage package, and not to the package itself, provides the following advantages: dispensing with the operation problems, in particular when the package is immersed in a pool for loading spent fuel assemblies. Indeed, if the package had to be provided with such an envelope as is for example suggested in document FR 2 467 468, the contaminated water of the pool could thereby penetrate the envelope through the air intake aperture, thus making the decontamination of the package particularly complex before transport; the shroud according to the invention, which forms a kind of envelope about the external surface of the package, is intended to improve package cooling in a horizontal configuration. In the solution of document FR 2 467 468, providing such an envelope on the package as well as structural elements to attach the envelope to the package, can strongly compromise the efficiency of cooling the same when in a vertical position, as assumed in particular in a storage configuration. This drawback does not occur in the invention, since the shroud is integrated to the support; generally, transferring the “cooling of the bottom part of the package” function to the support enables it to be decorrelated from other safety conventional functions of the package. Thus, it is not necessary to justify the envelope impact, which is a further structural characteristic, towards regulatory requirements; still in the case where the package is equipped with such an envelope, its overall dimension can thereby become incompatible with facilities. Conversely, if a same overall diameter is desired to be preserved, that results in reducing the package capabilities. The integration of the shroud within the supporting device also makes it possible to: reduce the number of envelopes/shrouds to be made, and thus decrease the coasts since a same supporting device is intended to a fleet of several packages; reduce the technical problem related to thermal aspects, without modifying existing packages: it is sufficient to place them on the support in accordance with the present invention; optimise the shroud to reduce the hot zone at the bottom part of the package. Indeed, with the suggested invention, it is not necessary to fully wrap the package. In particular, a shroud is not required in the top part when the package is considered in a horizontal position, whereas prior art suggests a shroud fully wrapping the package. On the contrary, the invention is a simpler and less bulky solution which makes it possible to address satisfactorily/in an optimised way the technical problem of cooling a localised zone (bottom point of the package). The invention preferably has at least one any of the following optional characteristics, taken alone or in combination. Said supporting means comprise first supporting means intended to receive a package head part, as well as second supporting means intended to receive a package bottom part, said first and second supporting means being axially spaced apart by an axial spacing distance (Dea), and the air guide shroud has preferably an axial length (La) substantially identical to the axial spacing distance (Dea). Said shroud includes a first axial end attached to said first supporting means, as well as a second axial end attached to said second supporting means. Alternatively, or simultaneously with the solution of attachment on the supporting means just being mentioned, said shroud is attached to said structural base of the supporting device. The axial spacing distance (Dea) is between 1.5 and 4 m. Said shroud is generally of a semi-cylindrical shape, pierced by said at least one cooling air intake aperture. For example, the transverse cross-section of said shroud is generally of a semi-circular shape. According to another example, the transverse cross-section of said shroud is generally of a semi-octagonal shape, the side closest to the structural base of which is arranged in parallel with the horizontal direction. Preferably, the median axial vertical plane of the supporting device, which is orthogonal to the plane of the transverse cross-section of the shroud, makes up a plane of symmetry for the shroud. Advantageously, by virtue of the tilted side of the semi-octagonal cross-section, the shroud can suck a greater air amount and facilitate the gradual downward descent of cold air. In addition, the semi-octagonal shaped structure has the advantage to resemble a cylindrical shape and thus enables a cooling air channel with a thickness more or less constant to be achieved, while at a lesser cost. In the case of the semi-octagonal cross-section, said side closest to the structural base is pierced by said at least one cooling air intake aperture. In this regard, said at least one cooling air intake aperture is preferably such that it is arranged at a bottom point of the shroud. That advantageously contributes to improving cooling, because the air stream can circulate on or in close proximity with the hot bottom point of the package. Alternatively, the cooling air intake aperture can be arranged in the proximity of a bottom point of the shroud, and not precisely on the same bottom point. Said at least one cooling air intake aperture extends on the entire axial length (La) of the shroud, and, more generally, preferably on at least 90% of this axial length of the shroud. Said at least one cooling air intake aperture has a transverse width between 100 and 500 mm, and is preferentially in the order of 300 mm. A free space is provided under said shroud, said free space having, at a bottom point of the shroud, an under-shroud height between 50 and 400 mm, and preferentially in the order of 200 mm. In this regard, it is noted that in some cases, the structural base includes stringers connecting the supporting means, as in the case of a conventional chassis. In this case, the bottom point of the shroud can be located below a top point of the stringers, that is the shroud is partly arranged in the space defined between the stringers, but always with a minimal under-shroud height as defined above. Preferably, said under-shroud height is higher than or equal to half the transverse width of the cooling air intake aperture. By way of indicating purposes, said shroud has a thickness between 1 and 5 mm, preferably made using a bent plate, in particular in the case of the generally semi-octagonal shaped cross-section. According to a first application, the supporting device forms a package transporting/storing chassis, possibly intended to be manipulated with the package when the same is supported by the device. In this case, the chassis can for example be placed on the platform of a radioactive material transporting system, for example the platform of a railroad car belonging to a railway transport system, or even the platform of a trailer belonging to a road transport system. According to a second application, the structural base forms all or part of a platform of a railroad car belonging to a railway transport system, or forms all or part of a platform of a trailer belonging to a road transport system. In this application, the supporting device according to the invention is directly integrated to the structure of the transport system, such that it is not designed to be manipulated, but intended to remain fixedly on the vehicle of which it is an integral part. The invention has also the object to provide an assembly comprising a radioactive material transporting/storing package, as well as a supporting device as described above, said package being supported in a horizontal position on said device, with a part of a side body of the package housed in said cavity defined by the cooling air guide shroud. Preferably, said package includes manipulation trunnions, and said means for supporting the device include housings each receiving one of said trunnions. According to another possibility, said means for supporting the device include at least two cradles on which the side body of the package rests. Regardless of the design retained, the side body of the package includes preferably an external diameter between 1 and 2.5 m. To improve draught, the cooling air guide shroud has preferably two opposite transverse ends, each located on or in the proximity of a median axial horizontal plane of the package. Preferentially, the internal surface of the shroud and the external surface of the side body of the package define therebetween a cooling air circulation channel, with an average thickness between 50 and 200 mm. In this regard, it is noted that the shroud fulfils two functions. The first function, being essential, consists in entering fresh air down the package. The second function consists in circulating at best air about the package, once the same has entered the shroud. By nature of the natural convection, the air which circulates is stuck to the side wall of the package. However, draught is actually more efficient with a shroud substantially parallel to the side surface of the side body of the package. Thus, preferentially, it is contemplated that the internal surface of the shroud and the external surface of the side body of the package define there between a cooling air circulation channel with a substantially constant thickness. In other words, both these surfaces are substantially parallel, so as to maximise the sucking flow rate, and improve thereby draught. Finally, one object of the invention is to provide a road or railway radioactive material transporting system, comprising a supporting device as described above, said structural base of the supporting device being fastened to a platform of the transport system, or forming all or part of this platform. Further advantages and characteristics of the invention will appear in the non-limiting detailed description below. In reference first to FIGS. 1 to 3, an assembly 100 according to a first preferred embodiment of the invention is represented, this assembly 100 comprising a package 1 for transporting/storing radioactive materials, as well as a supporting device 3 supporting the package. In this embodiment, the device 3 takes the form of a transporting/storing chassis resting for example on the surface of the ground 5. The package 1 is independent of the supporting device 3, on which it can be temporarily attached removably, for example using straps, reinforcements, trunnions, etc. Conventionally, the package 1 is provided with a side body 2, a bottom and a lid sealing a package aperture opposite to the bottom. The bottom and the lid can be respectively covered with two shock absorbing caps 6 mounted at the ends of the package body, as is visible in FIGS. 2 and 3. The package 1 has a longitudinal axis 8 centred relative to the side body 2, and passing through the lid as well as the bottom of the same package. The axis 8 is arranged substantially in parallel with the chassis 3. Thus, when the package 1 rests in a horizontal position on the chassis 3, its longitudinal axis 8 is also horizontally oriented. Also conventionally, the package forms an external envelope of a pack and defines a cavity 7 acting as a radioactive material housing, and possibly a storage basket 9. The radioactive materials can for example be waste cases, or even nuclear fuel assemblies 11. The feature of the invention resides in the design of the transporting/storing chassis 3, which will be now detailed still in reference to FIGS. 1 to 3. Overall, the chassis 3 includes a structural base 10, as well as means 12 for supporting the package which are carried by the base 10. In this first preferred embodiment, the structural base is made from main stringers 14 extending horizontally along the longitudinal direction of the assembly, as well as from connecting stringers 16 connecting the main stringers 14 and extending horizontally along the transverse direction of the assembly 100. All the stringers 14, 16 are situated preferably in a same plane, corresponding to the plane of the structural base 10. The supporting means 12 are in turn distributed into first supporting means associated with a package head part 2a, and second supporting means associated with a package bottom part 2b. More precisely, the first supporting means comprise two posts 18a vertically upwardly projecting from the structural base, whereas the second supporting means comprise two posts 18b analogously projectingly arranged. The first and second posts 18a, 18b each include, at an upper end, a housing 20 receiving a manipulation trunnion 22 equipping the package side body 2. Each trunnion 22 is conventionally projectingly arranged transverse from this side body 2, the external diameter of which is between 1 and 2.5 m. When this side body is equipped with cooling fins at the periphery thereof, this diameter value integrates the presence of these fins. The axial spacing distance Dea between the first and second posts 18a, 18b is between 1.5 and 4 m, whereas the total length Lt of the side body 2 is between 2 and 6 m, these values being considered along the direction of the axis 8, corresponding to the axial/longitudinal direction of the assembly 100. In this embodiment, the space between the first and second posts 18a, 18b is functionalised, since it integrates a cooling air guide shroud 30 for the package by natural convection. This shroud 30 is located at least partly above the structural base 10, and defines an upwardly open cavity 32 in which a part of the package is intended to be housed when the same is supported in a horizontal position on the first and second posts 18a, 18b. To allow draught, the shroud 30 comprises, in a bottom part thereof, at least one cooling air intake aperture 34 in the cavity 32. This aperture 34 is arranged at a bottom point of the shroud, and preferably extends on an axial length identical to the axial length La of the shroud, substantially identical to the axial spacing distance Dea between the first and second posts 18a, 18b. Indeed, a first axial end 36a of the shroud is attached to the first posts 18a, whereas a second axial end 36b opposite to the first one is attached to the second posts 18b. In this preferred embodiment, the shroud 30 is generally of a semi-cylindrical shape, with a generally semi-circular shaped transverse cross-section, the centre of which is located on or in close proximity of the axis 8. In the preferred case where the aperture 34 extends on the entire axial length La of the shroud 30, the latter thereby takes the form of two cylinder quarters separated by the aperture 34, the transverse width Ltr of which is between 100 and 500 mm, and preferably about 300 mm. Furthermore, a free space 38 is provided under the shroud, the bottom limit of this free space consisting of the ground surface 5 between the main stringers 14. At the bottom point of the shroud 30, the under-shroud height Hsc of this free space 38 is between 50 and 400 mm, and preferentially in the order of 200 mm. More generally, for an increased efficiency, the under-shroud height Hsc is such that it is higher than or equal to half the transverse width Ltr of the cooling air intake aperture 34. The median axial vertical plane 40 of the assembly 100 passes longitudinally and symmetrically through the aperture 34. On either side of this plane 40, the shroud 30 has two opposite transverse ends 42a, 42b, each located on or in the proximity of a median horizontal axial plane 44 of the package 1. The trunnions 22 equipping the side body 2 have also this median plane 44 passing symmetrically therethrough. In reference more specifically to FIG. 3, it is noted that the internal surface of the shroud and the external surface of the side body of the package define therebetween a cooling air circulation channel 50, with an average thickness between 50 and 200 mm. By having this thickness substantially constant and relatively low, that is by applying a parallelism between both abovementioned surfaces defining the channel 50, the cooling air can indeed circulate at best about the assembly, by natural convection. More precisely, the shroud 30 specific to the invention enables the package cooling to be improved in a horizontal position, at its bottom part, by virtue of a natural convection effect of the air which first penetrates the aperture 34, before circulating in the channel 50, and then upwardly escaping at the transverse ends 42a, 42b of this shroud. The conventionally hot zone at the bottom part of the assembly is thus advantageously reduced in terms of extent and maximum temperature, at a lesser cost without lowering the thermal power allowed within the package. According to another embodiment represented in FIG. 3a, the shroud 30 has a generally semi-octagonal shaped transverse cross-section, the side 54 closest to the structural base 10 of which is arranged in parallel to the horizontal direction, that is parallel to the axis 8. In this embodiment, the median axial vertical plane 40 of the supporting device makes up a plane of symmetry for the shroud 30, whereas the other median plane 44 delimits upwardly the octagonal half cross-section. Both tilted lateral sides 56 enable a greater amount of air to be sucked and facilitate the gradual downward cold air descent. In this embodiment, the thickness of the channel 50 between the shroud 30 and the external surface of the lateral body 2 is slightly variable because of the geometry difference between both facing elements. Its average thickness remains however in the abovementioned value range. The horizontal side 54 closest to the structural base 10 is pierced with the cooling air intake aperture 34, centred on the same side 54. The shroud 30 is for example made using a plate with a thickness of 1 to 5 mm, folded at the angles of the octagonal half cross-section. According to yet another embodiment shown in FIG. 3b, the shroud 30 has a first part 30a analogous to the shroud 30 of FIG. 3, in that it has a generally semi-circular shape transverse cross-section. However, this first part 30a integral with the posts 18, 18b has a thickness increasing from top to bottom, to form two longitudinal lower rims 60, each facing another rim 62 formed by a second part 30a of the shroud, attached to the structural base 10 at an upper part thereof. By way of example, the second part 30b is in the form of a longitudinal structure parallel to the axis 8, and with a triangular transverse cross-section such that two of its sides respectively form both rims 62. Each couple of rims 60, 62 forms a cooling air intake aperture 34, the orientation of which can be controlled. Preferably, the aperture 34 located vertically close to the bottom point of the package 1, but on the left side of the median plane 40, is oriented to deliver air to the right in the channel 50, whereas the aperture 34 located on the right side of the median plane 40 is oriented to deliver air to the left in the channel 50. That enables the cooling air to be moved closest to the critical bottom point of the package 1, for a better cooling. According to a second preferred embodiment of the invention represented in FIG. 4, the first and second supporting means have here the form of two cradles 18a′, 18b′, on which the side body 2 of the package 1 rests. The cradles can be closed on top by reinforcements 64 enabling the side body of the package to be fully surrounded, in order to improve holding thereof. In this second embodiment, the structural base 10 can be identical or analogous to that of the previous embodiment, or be in a more solid shape, as has been depicted in FIG. 4. The shroud 30 extends along the same axial length La, also corresponding to the axial spacing distance Dea between both cradles 18a′, 18b′. Regardless of the contemplated design, it is noted that according to a first application discussed above, the supporting device 3 forms a package transporting/storing chassis, possibly intended to be manipulated with the package when the same is supported by the device. In this case, the chassis can for example be placed on the platform of a radioactive material transporting system, for example the platform of a railway car belonging to a railway transport system, or even the platform 70 of a trailer 72 belonging to a road transport system 74, as has been depicted in FIG. 5. Alternatively, as has been depicted in FIG. 6, it is provided that the structural base 10 forms all or part of a platform of a railway car 80 belonging to a railway transport system 82, or forms all or part of a platform of a trailer belonging to a road transport system. In this application, the supporting device according to the invention is directly integrated to the structure of the transport system, such that it is not designed to be manipulated, but intended to fixedly remain on the vehicle of which it is an integral part. In FIG. 6, the railway car 80 is conventionally equipped with a so-called “canopy” element 80, mounted to the platform 10 of this railroad car and intended to cover the assembly 100. This element 86 can be provided in several parts sliding on the platform, and equipped with grids 88 enabling introduction and discharge of air, in particular for circulating the cooling air intended to pass through the shroud 30 specific to the invention. Of course, various modifications can be provided by those skilled in the art to the invention just described, only by way of non-limiting examples.
	summary
	abstract	An electron gun is composed of a hemispherical cathode (1) and a second bias electrode (8) having apertures (9, 7, 11) along an optical axis of an electron beam fired from the electron gun, a first bias electrode (6) and an anode (10), arranged in that order, as well as a controller for variably controlling an electric potential applied to the first and second bias electrodes. The controller, for example, holds the sum of the electric potentials of the first and second bias electrodes relative to the cathode (1) substantially constant. Further, by adding one or more third bias electrode(s) (20) between the first and second bias electrodes (6, 8) as necessary, the intensity of the electron beam discharged from the high-intensity, high-emittance electron gun can be adjusted without affecting the current density angular distribution.
044774117	description	Conveniently the helium gas pressure alternates between a relatively high value and a relatively low value so that in a square lattice arrangement of rods, for example, a rod with a helium gas pressure at one of the values has as its closest neighbours up to four rods with a helium gas pressure at the other of the values. Such an arrangement of a 4.times.4 array of fuel rods is shown diagrammatically in the accompanying FIG. 1. The rods 1 are filled with helium at a relatively high pressure and the rods 2 which alternate with the rods 1 are filled with helium at a relatively low pressure. By arranging for the differing helium gas pressures in a fuel element, in accordance with the invention, the result of a transient at a temperature below that at which the high pressure rods would be unstable (and therefore liable to rupture) can be swelling of the high pressure rods without interference from their low pressure neighbours (which should neither swell significantly nor rupture). On the other hand in a transient at higher temperatures the high pressure rods would be expected to rupture during the rise in temperature following loss of coolant so that they would not provide any restraint to significant deformation of their low pressure neighbours if the temperature subsequently rose high enough for this to occur. Blockage of coolant channels should therefore not be significant because, owing to the lack of restraint in either case, the blockage will not reach the maximum otherwise attainable. The actual pressures selected will, of course, depend on the design of the fuel element and, in particular, on the ductility of the fuel rod sheath material which, with the pressure, will be a determining factor in the temperature and dilation at which the high pressure rods fail. It will be appreciated that, as well as taking into account the factors which are significant to the present invention, the optimising of a fuel element design has to consider the effect of such matters as the cost of materials, their absorption of neutrons and the physics of reactor control e.g., the spacing of the fuel rods. Thus there are practical limits to the specification of the sheath which is currently of a zirconium/niobium alloy containing 1/2-21/2% niobium or one of the zirconium/tin alloys known as Zircaloy 2 and Zircaloy 4. With these alloys and a sheath thickness such that the sheath has the capacity to strain to touch the sheaths of neighbouring fuel rods--to obtain maximum advantage from the invention--a typical high helium pressure on filling is 2-3 MPa, leading to failure of high pressure rods above about 750.degree. C. A corresponding typical low helium pressure on filling is 0.5-1.5 MPa but the low pressure value may be as high as 1.75 MPa. Variations of this order in internal pressure do not unduly affect the performance of a fuel element during normal reactor operation. The invention may therefore be introduced in existing fuel element designs without difficulty. In general the wider apart the high and low pressure values are the greater the benefit for the purpose of the invention but the values to be chosen for a particular fuel rating are a matter of technical and economic judgement in each case; they have to be commensurate with both safe and economic operation of the reactor in which the fuel is to be used. They may be determined in conjunction with computer models of fuel performance in normal situations. Thus the high pressure value should not be greater than the reactor coolant pressure and there should be a safety margin allowed for this. Allowance should also be made for increase in pressure with operating temperature and for fission product gas release, for example, and the eventual high pressure value will be calculated accordingly. Similarly in calculating the low pressure value consideration has to be given to the effect of a lower pressure on such parameters as creep of the sheath material on to the fuel and fission product gas release, both of which will be modified further by the rise in fuel temperature which is another consequence of lowering the helium gas pressure. Thus, from experiments performed on fuel rods of a particular design at a range of initial internal filling pressures to predict the accident conditions under which the fuel rods will be dilated to the point of rupture a curve such as curve A in FIG. 2 may be constructed. A second curve B may be constructed from calculations of the lower limits to the conditions under which the rods would strain to produce axially extending deformations (swelling) leading eventually to rupture. The high and low level pressures are then so selected that whatever the temperature the high and low pressure rods would not both be swelling, irrespective of the changes in pressure occurring during the lifetime of the rods in a reactor, these changes being calculated using a computer modelling code. A typical fuel element to which the invention may be applied is shown diagrammatically in FIG. 3 and an example of the fuel rods 1, 2 is shown in FIG. 4. In FIG. 3 there is a cluster of fuel rods 1, 2 arranged in a square array between a base plate 3 and a top member 4. The fuel rods are supported intermediately by grids 5 fitted with springs (not shown). In each individual fuel rod 1, 2 (as shown in FIG. 4) there is a column of uranium dioxide fuel pellets 6. The pellets are contained in a sheath 7 closed by end plugs 8, 9. At each end of the column of pellets 6 is an insulating pellet 10, 11. A spring 12 extends through the gas plenum 13 between the upper insulating pellet 10 and the top end plug 8.
052231810	summary	FIELD OF THE INVENTION The present invention concerns a process for removing radioactive thorium and its radioactive daughters from magnesium slag and for reducing the volume of the radioactive waste that requires disposal. BACKGROUND OF THE INVENTION Radioactive waste sites exist in the United States that contain large volumes of material, several sites are in excess of 100,000 cubic yards. The number of such sites and concern for their management has significantly increased over recent years because of renewed concern over environmental issues, including the disposal of radioactive waste. The best method for the removal of radioactivity from such sites and their long term disposal requirements concerns many governmental agencies and private industry. The number of these sites that can treat and handle the huge amounts of radioactive waste are limited, due in part to the difficulty in identifying and siting new treatment and disposal facilities. Usual processing of these radioactive sites requires the treatment of large quantities of material, only a portion of which is in fact usually radioactive. Because of tremendous difficulties in economically treating such massive quantities of material to remove the radioactive portion and also meet the radioactivity level requirements for disposal set by government agencies, the best disposal method employed to date has been burial of the radioactive material. The burial method requires hauling large quantities of material, that are regulated as radioactive waste material, frequently many miles to an approved burial site. Therefore, economical methods for the reduction of the volume of the radioactivity for disposal at these sites have been actively sought. Several methods for a volume reduction of radioactive waste have been explored in the literature. Examples of review articles that describe the issues are: Energy Digest 15(4), 10-16 (1986), "World Status of Radioactive Waste Management"; PA1 Karl Heinz et al., Nuclear Engin. and Design 118, 115-122 (1990), "Volume Reduction, Treatment and Recycling of Radioactive Waste"; PA1 "Low-Level Radioactive Waste Reduction and Stabilization Technologies Resource Manual" (December 1988) by Ebasco Services Inc., Bellevue, Wash. for EG&G Idaho, Inc. under subcontract C85-131069 and for the U.S. Department of Energy, Idaho Operations Office under contract DE-AC07-76IDO1570; PA1 A. H. Kibbey and H. W. Godbee, "A State-of-the-Art Report on Low-Level Radioactive Waste Treatment", Oak Ridge National Laboratory, Oak Ridge, Tenn. under the Nuclear Waste Programs ORNL/TM-7427 (1980); and PA1 "Technological Approaches to the Cleanup of Radiologically Contaminated Superfund Sites" by the U. S. Environmental Protection Agency, No. EPA/540/2-88/002 (August 1988). PA1 a) extracting magnesium from a magnesium slag, which slag contains radioactive thorium and its daughters: PA1 b) forming an aqueous magnesium slurry from the magnesium slag and water; PA1 c) reacting the magnesium slurry with carbon dioxide; PA1 d) selectively concentrating the radioactive thorium and its daughters such that the radioactivity is separated from the magnesium; and PA1 e) reducing the volume and/or weight of radioactive solids for disposal as radioactive waste. When the radioactive component is a solid, then various physical separation techniques have been investigated based on methods involving: screening; classification; gravity concentration: and/or physical separation using flotation. The screening technique separates components on the basis of size and can be used either on dry material or water can be added, the material is separated by passing it through certain size screens. The classification technique is used to separate particles of material based on their settling rate in a liquid. The gravity concentration technique utilizes density differences to separate materials into layers. The flotation technique is based on physical and chemical phenomena as well as particle size differences. One technique based on gravity and particle size differences is taught in U.S. Pat. No. 4,783,253. In general, however, physical separation techniques will not be useful if the radioactive material is distributed uniformly within each particle size throughout all of the components comprising the mixture. When the radioactive component is in solution, then filtration, carbon treatment, ion exchange, and/or precipitation techniques are often used. Care must be exercised if a person is considering using any one of these techniques since a high degree of selectivity is required. For example, a precipitation technique may concentrate the majority of the radionuclides in a solid matrix, but if the precipitation was not quantitative then the solution from which the precipitation was preformed may still have sufficient radioactivity to be of concern for disposal. Thus if the process is not selective, the total volume of material for disposal after such processing can increase. These concerns have been raised by Raghaven et al. ["Technologies Applicable for the Remediation of Contaminated Soil at Superfund Radiation Sites", U. S. Environ. Prot. Agency Res. Dev., [Rep.] EPA (1989), EPA/600/9-89/072, Int. Conf. New Front. Hazard. Waste Management, 3rd. ed., 59-66 (1989)] where they indicate that of the 25 contaminated Superfund sites discussed that no chemical extraction or physical separation techniques have actually been used in a remediation situation and that their use must be approached with extreme caution. Some volume reduction techniques involve the use of incinerators and compactors. If incineration is used, then the off-gases and particulates that are produced must be constantly monitored and treated to ensure that radioactivity is not being released to the environment. Supercompactors, which are compactors that can exert forces in excess of 1,000 tons, have been used to achieve even greater reductions in volume. However, these supercompactors represent a very large capital investment. Volume reductions based on chemical extraction techniques using mineral acids have been reported. For example, U.S. Pat. No. 4,689,178 discloses the use of sulfuric acid in the recovery of magnesium sulfate from a slag containing magnesium and uranium metal and the oxides, fluorides and mixed oxides and fluorides of the metals. The desired outcome is that the radioactivity will occupy less volume than it did in the original slag. A similar process is described in U.S. Pat. No. 2,733,126. A process for the treatment of Magnox fuel element debris is described by D. Bradbury in "Development of Chemical Methods of Radioactive Waste Management for U. K. Power Reactor Sites", ANS/DOE Treatment & Handling of Radioactive Wastes (Batelle/Springer-Verlag) Conf., Richland, Wash., pp. 377-380 (April 19-22, 1982). Magnox alloy consists essentially of magnesium metal where about 1% of other alloying elements have been added. After irradiation, the levels of long-lived radioisotopes is reported to be low. Minor constituents in the waste debris, for example the approximately 5 G springs that are used with the spent Magnox fuel elements are produced from a nickel alloy that contains small amounts of cobalt. During irradiation the cobalt becomes activated to give cobalt-60 and the resulting radioactivity of the springs is far greater than from the irradiated Magnox. The process to isolate the radioactive debris from the Magnox alloy involves corroding away the magnesium in an aqueous medium. The process is conducted in a batch wise manner with large quantities of rapid flowing fresh water with carbon dioxide sparging. Care must be taken to maintain the magnesium concentration below the solubility limit, hence the large quantities of water. Since the dissolution also produces hydrogen gas with an exothermic reaction, proper handling techniques are required. A typical Magnox batch dissolution would take 20 days. The degree of dissolution of some of the radionuclides associated with the Magnox process is given by Bradbury et al. in "Magnox Dissolution in Carbonated Water. A Method of the Separation and Disposal of Magnox from Fuel Element Debris Waste", Water Chem. 3, 345-352 (1983) BNES, London. For cobalt-60, 29% was dissolved in the effluent. The above issues have resulted in large increases in cost associated with the disposal of waste [see, for example, "Low-Level Radioactive Waste Regulation", ed. Michael E. Burns, pub. Lewis Publishers, inc. (1988)]. The need therefore to minimize the amount of radioactive waste that has to be placed in an approved landfill or treated in other ways has become of critical importance. To date no technique exists which is cost effective, safe to the environment and technicians, and attains the selectivity needed for the radioisotopes. SUMMARY OF THE INVENTION The present process provides a highly selective, non-toxic and economical process for selectively concentrating the radioactive thorium and its daughters found in magnesium slag using recyclable reagents to concentrate radioactive thorium and its daughters from the magnesium slag, to provide magnesium reclamation, and to reduce the amount of radioactive waste for disposal. Specifically, it has now been found that in a process for separating magnesium from a magnesium slag using water and carbon dioxide, the improvement comprises:
	abstract	The present disclosure relates to a gas field ion source comprising a housing, an electrically conductive tip arranged within the housing, a gas supply for supplying one or more gases to the housing, wherein the one or more gases comprise neon or a noble gas with atoms having a mass larger than neon, and an extractor electrode having a hole to permit ions generated in the neighborhood of the tip to pass through the hole. A surface of the extractor electrode facing the tip can be made of a material having a negative secondary ion sputter rate of less than 10−5 per incident neon ion.
042726824	abstract	An ion milling machine specimen elevator comprising a vertically oriented piston which supports a specimen holder at its top and is movable between a lowered operating position and a raised viewing position. When the piston is in the lowered operating position, it is slowly rotated about its vertical axis by a suitable drive. The elongated piston passes through an O-ring seal into an evacuated ion milling or work chamber. At the bottom of the work chamber is disposed a pneumatic control cylinder into which the piston extends. The piston can be moved up or down by altering the pressure in the pneumatic cylinder. During ion milling the piston is at its lowest position in the evacuated work chamber and is held there by pressurized gas in the pneumatic control cylinder. A second small chamber is provided above the work chamber for specimen viewing and specimen exchange. The disclosed specimen elevator can move the specimen into the second chamber and at the same time provide a seal so the work chamber does not lose vacuum during specimen viewing or exchange. If it is desired to remove the specimen from the work chamber without disturbing its vacuum, the pressure in the pneumatic control cylinder is released and the elongated piston is automatically forced to its highest position by the exerted atmospheric pressure. As the elongated piston rises to its upper position the top of the piston passes through a second O-ring seal, at the top of the work chamber, then into the small second chamber. As the piston moves into the small second chamber, it seals the work chamber from the small second chamber so air admitted to the second chamber does not enter the work chamber. The small chamber can be lifted from the larger work chamber after the internal pressure of the small chamber is raised to atmospheric. Removing the small chamber exposes the specimen holder, allowing the specimen to be removed or closely examined to study the progress of the ion milling operation. The specimen is reinserted into the work chamber by replacing and then evacuating the small chamber and then by repressurizing the pneumatic control cylinder. This forces the piston to move through the seal between the work chamber and the small chamber to its lowest position. The piston has a beveled gear attached thereto which engages a driven bevel gear when the piston is in the lowered operating position to slowly rotate the specimen in the work chamber.
	claims	1. A method for coupling a control rod drive mechanism to a rod cluster control assembly in a nuclear reactor vessel, the method comprising:providing: a reactor vessel having a top head and an interior cavity; a nuclear fuel core supported in the interior cavity; a rod cluster control assembly positioned at a top of the fuel core and comprising a plurality of control rods configured for removable insertion the fuel core; a control rod drive mechanism mounted externally above the reactor vessel; a drive rod assembly including a drive rod mechanically coupled to the control rod drive mechanism and extending into the interior cavity of the reactor vessel, and a grapple assembly disposed on an end of the drive rod and including an electromagnet;lowering the drive rod assembly;contacting the drive rod assembly with a top end of a drive rod extension extending vertically between the rod cluster control assembly and the top head of the reactor vessel, a bottom end of the drive rod extension contacting the rod cluster control assembly in a non-locking manner;engergizing the electromagnet to magnetically couple the drive rod assembly with the drive rod extension;raising the drive rod assembly by a first vertical distance;locking the bottom end of the drive rod extension with the rod cluster control assembly, wherein raising and lowering the drive rod assembly with the control rod drive mechanism raises and lowers the rod cluster control assembly for controlling the reactivity within the fuel core. 2. The method of claim 1, wherein the lowering step includes:engaging a plurality of radially biased lifting pins movably disposed in the grapple assembly with a lifting head disposed on the drive rod extension;retracting the lifting pins at least partially outwards into the grapple assembly;moving the grapple assembly downwards over the lifting head; andprojecting the lifting pins back inwards from a grapple body. 3. The method of claim 2, further comprising:engaging the lifting pins with a bottom of the lifting head;raising the drive rod assembly by a second vertical distance; anduncoupling a lifting head sleeve on the drive rod extension from a retaining collar in the reactor vessel. 4. The method of claim 1, further comprising:de-energizing the electromagnet;dropping the drive rod extension wherein the drive rod assembly remains stationary; anduncoupling the bottom end of the drive rod extension from the rod cluster control assembly. 5. The method of claim 2, further comprising:lowering the drive rod assembly while contacting the top end of the drive rod extension with the drive rod assembly;compressing a spring against the lifting head with the drive rod assembly;engaging the lifting pins with a vertically movable annular bobbin on the drive rod extension;lifting the bobbin into engagement with the lifting head;retracting the lifting pins at least partially outwards into the grapple assembly;moving the grapple assembly upwards over the lifting head; andprojecting the lifting pins back inwards from the grapple body, wherein the drive rod assembly is uncoupled from the drive rod extension. 6. The method of claim 1, wherein the locking step includes driving a plurality of locking elements radially outwards from the drive rod extension to engage a groove formed in the rod cluster control assembly, thereby locking the rod cluster control assembly to the drive rod extension. 7. The method of claim 6, wherein the locking elements are movably disposed in an adapter sleeve mounted on the bottom end of the drive rod extension, the adapter sleeve being partially inserted into an upward standing tubular mounting extension disposed on the rod cluster control assembly. 8. The method of claim 1, wherein the drive rod extension is slidably disposed in a guide tube of a drive rod extension support structure mounted between the fuel core and the top head of the reactor vessel. 9. The method of claim 8, further comprising raising and lowering the rod cluster control assembly inside the guide tube with the control rod drive mechanism.
042785014	claims	1. Spring element for holding down and bracing a fuel assembly against a hold-down plate upwardly limiting the reactor core of a nuclear reactor, comprising a spring-loaded rod-shaped member formed independently of the fuel assembly and being slidable axially into the fuel assembly, said rod-shaped member having a plurality of parts telescopically slidable together, and including a compression spring engaging two of said parts and, in neutral position of the rod-shaped member, urging said parts away from one another and forming said rod-shaped member into the greatest possible assumed length thereof, said rod-shaped member, in installed condition thereof, being mounted, at one end thereof, in at least one bore formed in a head of the fuel assembly and engaging the hold-down plate, at the other end thereof. 2. Spring element according to claim 1 wherein said compression spring is disposed around and extends along the length of the rod-shaped member. 3. Spring element for holding down and bracing a fuel assembly against a hold-down plate upwardly limiting the reactor core of a nuclear reactor, comprising a spring-loaded rod-shaped member formed independently of the fuel assembly and being slidable axially into the fuel assembly, said rod-shaped member being a plurality of parts telescopically slidable together, and including a compression spring urging said rod-shaped member, in neutral position thereof, into the greatest possible assumed length thereof, said rod-shaped member, in installed condition thereof, being mounted, at one end thereof, in at least one bore formed in a head of the fuel assembly and engaging the hold-down plate, at the other end thereof, the rod-shaped member being formed of three parts including a threaded bolt formed with a shaft and a head, an upper sleeve telescopically guidable on the shaft of said threaded bolt and engageable with said head of said threaded bolt, and an internally threaded lower sleeve wherein said threaded bolt is threadedly received for adjusting the combined length thereof, said lower sleeve and said threaded bolt being securable against relative rotation, said one end of the rod-shaped member being an end of said threaded bolt projecting beyond said lower sleeve and engageable in the fuel-element head. 4. Spring element according to claim 3 wherein said compression spring surrounds said rod-shaped member and both said upper and lower sleeves are formed with a respective collar at ends thereof forming opposite ends of said rod-shaped member, said collars serving as stops for said compression spring.
	claims	1. A detector system for a scanning electron microscope defining an optical axis along which an electron beam travels, the detector system comprising:four electron detectors arranged in a first plane and being offset one with respect to the other so as to define an aperture between said electron detectors for a free passage therethrough of said electron beam;an additional detector arranged in a second plane spaced at a distance from said first plane; and,said additional detector being disposed in said second plane so as to be centered with respect to said aperture. 2. The detector system of claim 1, wherein said four detectors have respective identical surfaces sensitive to electrons. 3. The detector system of claim 1, wherein said four electron detectors have respective rectangular or quadratic surfaces sensitive to electrons. 4. The detector system of claim 1, wherein said aperture is quadratic. 5. The detector system of claim 1, wherein said distance lies in a range between 0.1 mm and 5 mm. 6. The detector system of claim 1, wherein said aperture has a diameter or edge length between 0.05 mm and 1 mm. 7. The detector system of claim 1, wherein said electron detectors are diodes. 8. The detector system of claim 1, further comprising a signal evaluation unit for selectively applying one of the following for generating an image:(a) the individual detector signals of selected ones of said four detectors in said first plane;(b) the sum of the detector signals of said four detectors in said first plane; and,(c) the detector signal of said additional detector. 9. A scanning electron microscope defining an optical axis and comprising:an electron source for emitting a beam of electrons in a direction of propagation along said optical axis toward a specimen having a side facing away from said electron source;an electron optic focusing said beam of electrons to irradiate said specimen with a focused electron beam causing a first group of said electrons to scatter at said specimen with no change or only a slight change in the direction of propagation and a second group of said electrons to scatter at said specimen with a change in propagation;a specimen chamber for holding said specimen;a detector system mounted in said specimen chamber downstream of said side of said specimen;said detector system having electron detector means in a first plane and said electron detector means defining an aperture to permit a free passage of said first group of said electrons;said detector system including an additional detector in a second plane spaced at a distance from said first plane;said additional detector being disposed downstream of said aperture viewed in said direction of propagation;said electron detector means being disposed at a distance from said specimen; and,said aperture having dimensions and said dimensions and said distance being so selected that said first group of electrons passes through said aperture and impinges upon said additional detector and said second group of electrons impinges upon said electron detector means. 10. The scanning electron microscope of claim 9, further comprising a manipulator accommodated in said specimen chamber; and, said manipulator being adjustable in two mutually perpendicular directions in a plane perpendicular to said optical axis. 11. The scanning electron microscope of claim 10, further comprising a specimen table disposed in said specimen chamber and said specimen table being movable in a region within said specimen chamber; and, said manipulator being movable out of said region and being repositionable with high precision to a previous preset position. 12. The scanning electron microscope of claim 9, wherein said electron detector means comprises four electron detectors arranged in said first plane and conjointly defining said aperture. 13. The scanning electron microscope of claim 12, said electron detectors having respective identical surfaces sensitive to electrons. 14. The scanning electron microscope of claim 13, wherein said electron detectors are diodes. 15. The scanning electron microscope of claim 12, wherein said aperture has a diameter or edge length of less than 1 mm. 16. The scanning electron microscope of claim 12, wherein said four electron detectors have surfaces sensitive to electrons; said surfaces border directly on each other outside of said aperture so that regions insensitive to electrons arise between said electron detectors and have dimensions of less than 200 μm perpendicular to the edges of the detectors. 17. The scanning electron microscope of claim 12, further comprising a signal evaluation unit for providing an image generation in at least five modes; namely:(a) in a first mode, by applying only the signal of said additional detector for said image generation;(b) in a second mode, by applying the sum of the signals of said electron detectors for said image generation;(c) in a third mode, by applying selectable signals of individual ones of said electron detectors for said image generation;(d) in a fourth mode, by applying the sum of the signals of two of said electron detectors for said image generation; or,(e) in a fifth mode, by applying the sum of the signals of said electron detectors and of the signal of said additional detector for said image generation. 18. A detector system for a scanning electron microscope defining an optical axis along which an electron beam travels, the detector system comprising:four electron detectors arranged in a first plane and being offset one with respect to the other so as to define a quadratic aperture between said electron detectors for a free passage therethrough of said electron beam;said four electron detectors having respective rectangular or quadratic surfaces sensitive to electrons;an additional detector arranged in a second plane spaced at a distance from said first plane; and,said additional detector being disposed in said second plane so as to be centered with respect to said aperture. 19. The detector system of claim 18, wherein said four detectors have respective identical surfaces sensitive to electrons. 20. The detector system of claim 18, wherein said distance lies in a range between 0.1 mm and 5 mm. 21. The detector system of claim 18, wherein said aperture has a diameter or edge length between 0.05 mm and 1 mm. 22. The detector system of claim 18, wherein said electron detectors are diodes. 23. The detector system of claim 18, further comprising a signal evaluation unit for selectively applying one of the following for generating an image:(a) the individual detector signals of selected ones of said four detectors in said first plane;(b) the sum of the detector signals of said four detectors in said first plane; and,(c) the detector signal of said additional detector. 24. A scanning electron microscope defining an optical axis and comprising:an electron source for emitting a beam of electrons in a direction of propagation along said optical axis toward a specimen having a side facing away from said electron source;an electron optic focusing said beam of electrons to irradiate said specimen with a focused electron beam causing a first group of said electrons to scatter at said specimen with no change or only a slight change in the direction of propagation and a second group of said electrons to scatter at said specimen with a change in propagation;a specimen chamber for holding said specimen;a detector system mounted in said specimen chamber downstream of said side of said specimen;said detector system including four electron detectors in a first plane;said four electron detectors having respective rectangular or quadratic surfaces sensitive to electrons and conjointly defining a quadratic aperture to permit a free passage of said first group of said electrons;said detector system including an additional detector in a second plane spaced at a distance from said first plane;said additional detector being disposed downstream of said aperture viewed in said direction of propagation;said electron detector means being disposed at a distance from said specimen; and,said aperture having dimensions and said dimensions and said distance being so selected that said first group of electrons passes through said aperture and impinges upon said additional detector and said second group of electrons impinges upon said electron detector means. 25. The scanning electron microscope of claim 24, further comprising a manipulator accommodated in said specimen chamber; and, said manipulator being adjustable in two mutually perpendicular directions in a plane perpendicular to said optical axis. 26. The scanning electron microscope of claim 25, further comprising a specimen table disposed in said specimen chamber and said specimen table being movable in a region within said specimen chamber; and, said manipulator being movable out of said region and being repositionable with high precision to a previous preset position. 27. The scanning electron microscope of claim 24, wherein said electron detector means comprises four electron detectors arranged in said first plane and conjointly defining said aperture. 28. The scanning electron microscope of claim 27, said electron detectors having respective identical surfaces sensitive to electrons. 29. The scanning electron microscope of claim 28, wherein said electron detectors are diodes. 30. The scanning electron microscope of claim 27, wherein said aperture has a diameter or edge length of less than 1 mm. 31. The scanning electron microscope of claim 27, wherein said four electron detectors have surfaces sensitive to electrons; said surfaces border directly on each other outside of said aperture so that regions insensitive to electrons arise between said electron detectors and have dimensions of less than 200 μm perpendicular to the edges of the detectors.
	abstract	A nuclear power plant with an improved cooling system using nanoparticles in solid or fluid form is provided. The nanoparticles are delivered in locations such as the cold leg accumulator and high and low pressure pumps of an emergency core cooling system. Motor driven valves and pressurization can aid in the delivery. Methods for providing the nanoparticles are also provided.
055330789	claims	1. A nuclear fuel assembly having a predetermined overall length for a pressurized water reactor, comprising: (a) a lower tie plate having at least one aperture; (b) a guide tube having an upper end and a lower end, the lower end connected to the lower tie plate; (c) spacer grids spaced along the guide tube; (d) an upper tie plate which is attached to the upper end of the guide tube; (e) an instrumentation tube attached at one end to the lower tie plate and attached at an opposite end to the upper tie plate; (f) extended fuel rods which extend to the lower tie plate and which are spaced radially and supported along the guide tube by the spacer grids, at least one of the extended fuel rods having at a lower end a fuel rod lower end cap, the lower end cap being secured by a first spring which exerts a lateral force against the lower end cap within the aperture in the lower tie plate, the first spring being disposed within the aperture in the lower tie plate. 2. The nuclear fuel assembly for a pressurized water reactor as in claim 1 wherein the at least one of the extended fuel rods has an upper end, and the upper tie plate further includes a fuel rod support housing which extends down over the upper end of the at least one of the extended fuel rods. 3. The nuclear fuel assembly for a pressurized water reactor as in claim 2 wherein the fuel rod support housing is adapted to have at least one bore, the assembly further including a second spring positioned within the at least one bore in the fuel rod support housing of the upper tie plate, the second spring exerting a lateral force on the upper end of he at least one of the extended fuel rods positioned within the at least one bore in the fuel rod support housing of the upper tie plate.
	description	In a typical nuclear reactor heat is generated within the core of the reactor vessel as a result of nuclear fission. The heat is employed to generate steam, which in turn drives turbine-generators to produce electricity. In a pressurized water nuclear reactor the heat in the core is transferred to a coolant moderator, commonly borated water, which is transported under pressure to a steam generator that places the coolant in heat transfer relationship with a secondary fluid. The secondary fluid is vaporized into steam which is used to drive the turbine-generators. The nuclear fuel within the core is typically encapsulated in cylindrical, elongated rods often referred to as fuel elements. The fuel elements are maintained in a polygonal array and, in one preferred embodiment, extend in a longitudinal direction to a length of approximately fourteen feet. The array is generally referred to as a fuel assembly and is bounded by an upper and lower nozzle and maintained in position and appropriately spaced by fuel element support grids that are secured at spaced locations along the longitudinal length of the assembly. Interspersed among the fuel elements within the assembly are control rod guide tubes and instrumentation thimbles that are symmetrically arranged in place of fuel element locations and are used to guide the control rods and act as conduits for in-core instrumentation. The control rods are used to control the fission process by absorbing neutrons in the core that would otherwise react with the nuclear fuel. The control rods are movable into and out of the core through the guide tubes to control the level of reactivity. The coolant within the core that flows from a region below the fuel, up through each fuel assembly and out its nozzle, includes a moderator such as Boron that slows the speed of the neutrons to increase the efficiency of the fission process. When the control rods are removed from the core the corresponding thimble tubes are filled with the coolant moderator which increases the fission reactions in the fuel in the cells surrounding those guide tubes. A more detailed understanding of the operation of a pressured water nuclear reactor can be had by referring to U.S. Pat. No. 5,303,276 issued Apr. 12, 1994, entitled xe2x80x9cFUEL ASSEMBLY INCLUDING DEFLECTIVE VANES FOR DEFLECTING A COMPONENT OF THE FLUID STREAM FLOWING PAST SUCH A FUEL ASSEMBLY.xe2x80x9d FIG. 1 is a top plan view of a fuel assembly support grid 10 incorporating features of this invention and having a perimeter 12 formed in the shape of an equilateral, quadrilateral, polygon, or square. It should be appreciated, however, that the concepts of this invention can be applied to fuel element support grids employing different shaped perimeters, such as the hexagonal fuel assembly illustrated in the previously referenced U.S. Pat. No. 5,303,276. The grid assembly illustrated in FIG. 1 is constructed from an evenly spaced, parallel array of lattice grid straps 14, which intersect with a similar, orthogonally positioned, evenly spaced, parallel array of lattice grid straps 16. The lattice array is welded to a peripheral strap 20 which forms the perimeter of the grid. The walls of the straps, intermediate the intersections with the corresponding orthogonal straps, define cells through which the fuel elements, guide tubes and instrumentation thimbles pass. FIG. 1 illustrates a 17 by 17 array of cells, though it should be appreciated that the application of the principles of this invention are not affected by the number of fuel elements in an assembly. The lattice straps which form the orthogonal members 14 and 16 shown in FIG. 1, are substantially identical in design and are better illustrated in FIGS. 3 and 6 by reference character 18. While the lattice straps 14 and 16 are substantially identical, it should be appreciated that the design of some lattice straps 16 will vary from other lattice straps 16, as well as some straps 14 vary from other straps 14, to accommodate guide tube and instrument thimble locations. Reference character 42 in FIG. 1 identifies those cells which support fuel elements and reference character 34 shows the cells that are attached to the guide tubes and instrumentation thimbles. FIG. 3 provides the best view of the orthogonal intersections between lattice straps 14 and 16. Most walls of the cells that accommodate fuel elements are provided with a number of stamped, protruding segments that are tooled by appropriate dies as is known and used in the industry. The upper and lower stamped segments 26 bulge out in one direction and form dimples for supporting the fuel elements against juxtaposed diagonal springs which protrude from the opposite cell wall. The remaining centrally located, stamped section 28 in the same wall as the previously described dimples, bulges in the opposite direction into the adjacent cell and forms a diagonal spring for pressuring the fuel element against dimples 26 which protrude into the that adjacent cell from its opposite wall. The preferred design of the diagonal spring can better be appreciated by reference to U.S. Pat. No. 6,144,716 issued Nov. 7, 2000, which was filed contemporaneous herewith. Mixing vanes 32 extend from the upper edges of the lattice straps at some of the segments which form the walls of the cells 42 through which the fuel assemblies pass. In accordance with this invention, the mixing vanes are arranged in a predetermined pattern that can be better appreciated by referring to FIG. 1 and will be described more fully hereafter. The cells 34 support the guide tubes and instrumentation thimbles through which the control rods and the in-core instrumentation pass. The cells 34 differ from the fuel element support cells 42 in that they have none of the support members 26 or 28 protruding into their interior or mixing vanes 32 extending from their walls. The cells 34 further differ in that they have a concave, embossed section 36 at the center of the cell walls extending from the bottom to the top of the lattice strap. The curvature of the concave section is substantially matched to the circumferential curvature of the corresponding guide tubes or instrumentation thimbles that it mates with. The embossed grid locations accommodate guide tubes and instrumentation thimbles of a larger diameter than the fuel elements which provides greater clearance for control rod and instrumentation movement. This feature is particularly important in today""s competitive markets where demands for greater fuel economy has necessitated longer fuel burn-up cycles, which can induce some minor distortions within the fuel assemblies. In one preferred embodiment, the tubes and thimbles are welded to at least some of the embossed areas in each cell 34. The guide tubes and thimble cells 34 also differ from the fuel locations in that they have a rectangular notched section 40 cut-out of their lower side over the embossed area, which provides the welding surface for the attachment of a sleeve which supports the thimble tube. Weld tabs 30 are stamped at each intersection of the cell walls intermediate of the height of the cell and are folded out and welded to improve the crush resistant strength of the grid assembly. Each strap 18 terminates at the perimeter strap 20 to which it is also welded. FIG. 6 illustrates a portion of the lattice strap 18 that forms the wall to a single cell and extends just over the position where it would intersect with the corresponding, adjacent, orthogonal lattice straps to which it would be attached. The straps 18 are provided with slits 44 which in some cases extend from the bottom of the strap to half way up its height, at the intersection locations where it meets with the straps running in the orthogonal direction. The orthogonally positioned straps are provided with similar slits 44 that extends from their top surface to half way down the strap. The straps are then fitted together at their slits with one slit sliding over the other at each intersection to form an egg-crate pattern that locks the intersections and defines the cells. FIG. 6 does not show the weld tabs 30 that were previously described with reference to FIG. 3. FIGS. 4 and 5 illustrate the design of the perimeter straps 20. FIG. 4 shows one side of the perimeter strap 20, which includes protective tabs 46 of differing geometries, that extend from the upper and lower edges of the strap and are bent inwardly. The protective tabs function to avoid hang-up of the fuel assemblies against adjacent assemblies as they are inserted or withdrawn from the reactor core. The straps are tapered at their corners 48 and bent around the corners as shown in FIG. 5. Broadly, this invention overcomes the flow-induced fuel assembly vibrations experienced by some prior art mixing vane designs by providing a hydraulically balanced mixing vane pattern over a plane orthogonal to the longitudinal dimension of the fuel assembly, that produces a force, moment, and torque equilibrium due to uniformly distributed lift and drag forces. In addition, within each individual grid cell at the fuel element support locations, the inclined grid springs on adjacent cell walls, shown in FIG. 3 by reference character 28, age inclined in opposite directions in order to minimize any unbalanced torques due to the hydraulic lift forces acting along the edge of the springs. This arrangement further reduces the potential for producing a rotational twist bias on the fuel assembly. One embodiment for achieving the hydraulically balanced vane pattern of this invention is illustrated in FIG. 1, as applied to a square 17 by 17 fuel assembly array. For the purpose of defining the vane pattern, the grid is divided into four quadrants 50, 52, 54 and 56. Each quadrant is defined by the perimeter and lines drawn between the mid point of each perimeter segment and the center of the grid. In each quadrant the vanes are positioned at the cell corners over the fuel element locations and extend along lines parallel to a line extending from the center of the grid to the corresponding corner of the quadrant. Each quadrant contains the same number of vanes. The overall pattern in this embodiment forms an xe2x80x9cXxe2x80x9d about the central axis of the fuel assembly. In the embodiment illustrated in FIG. 1, the pattern in each quadrant can be replicated by rotating the entire grid in 90-degree increments about its center. Accordingly, the pattern is 90-degrees rotatable. The combination of rotatable and symmetrical features of this pattern produces a balance of the hydraulic forces acting against the vanes, thus enhancing the grid""s anti-vibration properties. In this preferred embodiment, the invention is shown as being applied to a quadrilateral fuel assembly design. It should also be appreciated that the invention can work equally as well in fuel assembly grid designs having a equilateral polygon perimeter shape with a different number of sides than is shown in this preferred embodiment; for example, the hexagonal design illustrated in U.S. Pat. No. 5,303,276 referenced above. In that case, the vane design regions would be defined by the perimeter and lines extending from the mid-point of the perimeter segments through the center of the grid. The vanes would still be positioned at the fuel element support locations and follow lines parallel to a line extending between the corresponding intersection of perimeter segments and the center of the grid. In this case, the design would be rotatable xe2x80x9cNxe2x80x9d degrees, wherein xe2x80x9cNxe2x80x9d equals 360 divided by the number of perimeter segments. Thus, the hydraulically balanced vane configuration of this invention can be applied to other grid configurations. Similarly, while in this embodiment the vane pattern has been shown supported from the upper edge of the grid, at the fuel element support cells, it should be appreciated that a similar result could be achieved by vanes supported at other locations along the assembly over a plane orthogonal to the longitudinal dimension of the fuel assembly. Accordingly, this invention provides an improved fuel assembly incorporating a support grid design and deflector vane pattern that optimize reactor coolant flow during operation in a manner that improves DNB performance with a minimum of vibration, reduces pressure drop and improves grid crush resistance strength. The grid of this invention also accommodates guide tubes and instrumentation thimbles of a larger diameter than the fuel elements, which increase the design clearance between the control rods and the guide tubes and lessons the likelihood of a control rod or instrumentation hang up.
048572608	abstract	In an automated first weld apparatus, a transporter conveys nuclear fuel cladding tubes successively to a welding station where a separate end plug is welded to an open end of each tube. Thereafter, the transporter indexes the tubes successsively through a cooldown station where the weld is cooled, to a reader station where a unique end plug serial number is read, and then to a succession of inspection stations where the internal and external weld characteristics are automatically examined. The resulting inspection data is correlated with the associated serial number for record purposes and tested against quality assurance standards pursuant to sorting the tubes into accepted and rejected lots.
	summary
	claims	1. A computed tomography (CT) imaging system comprising:a selectable pre-object filter module interposed between an X-ray source and an object to be imaged, the selectable pre-object filter module configured to absorb radiation from the X-ray source to control distribution of X-rays passed to the object to be imaged, the selectable pre-object filter module comprising plural pre-object filter configurations providing corresponding X-ray distributions, wherein the selectable pre-object filter module is selectable between the plural configurations to provide a selected pre-object filter configuration of the plural pre-object filter configurations to perform a desired imaging scan of the object to be imaged;a detector configured to receive X-rays that have passed through the object to be imaged; anda processing unit operably coupled to the selectable pre-object filter module and the detector, the processing unit configured to:identify an anatomy to be imaged;determine a corresponding image quality metric and radiation dose metric separately for each of the plural pre-object filter configurations based on particular operational parameters to be used to perform the desired imaging scan, wherein the operational parameters include tube voltage and tube current; andselect the selected pre-object filter configuration from among the pre-object filter configurations based upon the separately determined corresponding image quality metrics and radiation dose metrics. 2. The imaging system of claim 1, wherein the processing unit is further configured to implement the selected pre-object filter configuration for use in performing the desired imaging scan of the object to be imaged. 3. The imaging system of claim 1, wherein the selectable pre-object filter module comprises a plurality of discrete bowtie filters, wherein the processing unit is configured to select one of the discrete bowtie filters for use in performing the desired imaging scan of the object to be imaged. 4. The imaging system of claim 1, wherein the selectable pre-object filter module comprises a dynamically adjustable bowtie filter, wherein the processing unit is configured to adjust the dynamically adjustable bowtie filter to provide the selected bowtie configuration. 5. The imaging system of claim 1, wherein the processing unit is further configured to obtain a pre-scan, and determine a position of the object relative to a centered position using the pre-scan. 6. The imaging system of claim 5, wherein the processing unit is further configured to alert a user if the position of the object differs from the centered position by more than a threshold. 7. The imaging system of claim 5, wherein the processing unit is further configured to adjust a cradle position of a cradle upon which the object to be imaged is supported if the position of the object differs from the centered position by more than a threshold. 8. The imaging system of claim 5, wherein the processing unit is configured to determine a cradle position and channel occupancy for the object to be imaged, the channel occupancy corresponding to channels of the detector having a signal metric above a threshold, and to determine the position based on the cradle position and channel occupancy. 9. The imaging system of claim 1, wherein the processing unit is configured to determine a cradle position and channel occupancy for the object to be imaged, the channel occupancy corresponding to channels of the detector having a signal metric above a threshold, and to determine an attenuation for the object to be imaged based on the cradle position and channel occupancy. 10. A method comprising:identifying, with at least one processing unit, an anatomy to be scanned for a desired imaging scan by a computed tomography (CT) imaging system including a selectable pre-object filter module having plural pre-object filter configurations providing corresponding X-ray distributions;determining, with the at least one processing unit, a corresponding image quality metric separately for each of the plural pre-object filter configurations based on particular operational parameters to be used to perform the desired imaging scan, wherein the operational parameters include tube voltage and tube current;determining, with the at least one processing unit, a corresponding radiation dosage metric separately for each of the plural pre-object filter configurations based on operational parameters; andselecting, with the at least one processing unit, a selected pre-object filter configuration for performing the desired imaging scan of the anatomy to be scanned from among the plural pre-object filter configurations based upon the separately determined corresponding image quality metrics and radiation dosage metrics. 11. The method of claim 10, further comprising automatically implementing the selected pre-object filter configuration and performing the desired imaging scan using the selected pre-object filter configuration. 12. The method of claim 10, wherein the plural pre-object filter configurations correspond to a corresponding plurality of discrete bowtie filters, and wherein the selecting comprises selecting one of the discrete bowtie filters for performing the desired imaging scan. 13. The method of claim 10, further comprising obtaining a pre-scan, and determining, with the at least one processing unit, a position of an object to be imaged relative to a centered position using the pre-scan. 14. The method of claim 13, further comprising alerting a user if the position of the object differs from the centered position by more than a threshold. 15. The method of claim 13, further comprising adjusting a cradle dimension of a cradle upon which the object to be imaged is supported if the position of the object differs from the centered position by more than a threshold. 16. The method of claim 13, further comprising:determining, with the at least one processing unit, a cradle position and channel occupancy for the object to be imaged, the channel occupancy corresponding to channels of a detector having a signal metric above a threshold; anddetermining, with the at least one processing unit, the position based on the cradle position and channel occupancy. 17. The method of claim 10, further comprising:determining a cradle position and channel occupancy for the object to be imaged, the channel occupancy corresponding to channels of a detector having a signal metric above a threshold; anddetermining an attenuation for the object to be imaged based on the cradle position and channel occupancy. 18. A tangible and non-transitory computer readable medium configured to select a pre-object filter configuration for an object to be imaged, the tangible and non-transitory computer readable medium comprising one or more computer software modules configured to direct one or more processors to:identify an anatomy to be scanned for a desired imaging scan by a computed tomography (CT) imaging system including a selectable pre-object filter module having plural pre-object filter configurations providing corresponding X-ray distributions;determine a corresponding image quality metric separately for each of the plural pre-object filter configurations based on particular operational parameters to be used to perform the desired imaging scan, wherein the operational parameters include tube voltage and tube current;determine a corresponding radiation dosage metric separately for each of the plural pre-object filter configurations based on the operational parameters; andselect a selected pre-object filter configuration from among the plural pre-object filter configurations for performing the desired imaging scan of the anatomy to be scanned based upon the separately determined corresponding image quality metrics and radiation dosage metrics. 19. The tangible and non-transitory computer readable medium of claim 18, wherein the computer readable medium is further configured to direct the one or more processors to obtain a pre-scan, and determine a position of an object to be imaged relative to a centered position using the pre-scan. 20. The tangible and non-transitory computer readable medium of claim 18, wherein the computer readable medium is further configured to direct the one or more processors todetermine a cradle position and channel occupancy for the object to be imaged, the channel occupancy corresponding to channels of a detector having a signal metric above a threshold; anddetermine an attenuation for the object to be imaged based on the cradle position and channel occupancy. 21. The imaging system of claim 1, wherein the processing unit is further configured to select the selected pre-object filter configuration based on an impact of at least one of the pre-object filter configurations on acquisition parameters. 22. The imaging system of claim 1, wherein the processing unit is further configured to remove an inappropriate pre-object filter configuration when use of the inappropriate pre-object filter configuration requires adjustment of at least one of a tube current or voltage outside of a predetermined acceptable range.
	summary
	summary
	summary
	claims	1. A set material for neutron shielding and for maintaining sub-criticality, comprising:a matrix based on a vinylester resin selected from the group consisting of bisphenol A-type epoxy(meth)acrylate resins, novolac-type epoxy(meth)acrylate resins, epoxy(meth)acrylate resins based on halogenated bisphenol A, and resins obtained from an isophthalic polyester and a urethane, at least one polyamide, and an inorganic filler capable of slowing and absorbing neutrons, the inorganic filler comprising at least one hydrogenated inorganic compound and at least one inorganic boron compound. 2. Material according to claim 1, in which the polyamide is an aliphatic polyamide. 3. Material according to claim 2, in which the polyamide is chosen from among 11 polyamides, 12 polyamides 6–12 polyamides and mixes of them. 4. Material according to claim 1, in which the vinylester resin is a novolac-type epoxy(meth)acrylate resin. 5. Material according to claim 1, in which the hydrogenated inorganic compound is chosen from the group consisting of alumina hydrates and magnesium hydroxide. 6. Material according to claim 1, in which the inorganic boron compound is chosen from the group consisting of boric acid, colemanite, zinc borates, boron carbide, boron nitride and boron oxide. 7. Material according to claim 1, in which the hydrogenated inorganic compound is alumina hydrate with formula Al(OH)3. 8. Material according to claim 1, in which the inorganic boron compound is zinc borate with formula Zn2O14.5H7B6 or boron carbide. 9. Material according to claim 1, with an atomic concentration of hydrogen between about 4.5×1022 and 6.5×1022 at/cm3. 10. Material according to claim 1, with an atomic concentration of boron between about 8×1020 and 3×1021 at/cm3. 11. Material according to claim 1, in which the vinylester resin accounts for between 30 and 45% of the total mass of this resin, the polyamide and inorganic filler being capable of slowing and absorbing neutrons. 12. Material according to claim 11, in which the polyamide accounts for between 10 to 30% of the total mass of the vinylester resin, the polyamide and inorganic filler being capable of slowing and absorbing neutrons. 13. Material according to claim 1, with a density of between 1.3 and 1.6. 14. Process for preparation of a set material for neutron shielding and for maintaining sub-criticality comprising a matrix based on a vinylester resin selected from the group consisting of bisphenol A-type epoxy(meth)acrylate resins, novolac-type epoxy(meth)acrylate resins, epoxy(meth)acrylate resins based on halogenated bisphenol A, and resins obtained from an isophthalic polyester and a urethane, at least one polyamide and an inorganic filler capable of slowing and absorbing neutrons, the inorganic filler comprising at least one hydrogenated inorganic compound and at least one inorganic boron compound, comprising:(a) mix the vinylester resin, the polyamide, and the inorganic filler comprising at least one hydrogenated inorganic compound and at least one inorganic boron compound capable of slowing and absorbing neutrons, with at least one resin polymerization accelerator,(b) add at least one resin polymerization catalyst to this mix,(c) degas the mix tinder a vacuum,(d) pour the mix obtained into a mould, and(e) allow the mix to set in the mould. 15. Process according to claim 14, in which the mould is composed of a compartment of a packaging for transport, interim storage and/or ultimate storage of radioactive products. 16. Packaging for transport, interim storage and/or ultimate storage of radioactive materials, comprising at least one shield formed from the material as defined in any one of claims 1-3, 4, and 5-13.
052415724	claims	1. Apparatus for locating a floatable platform relative to an article submerged in a liquid, the improvement comprising support members arranged to be adjacent to the article, extendible members depending from the platform, the extendible members being locatable on the support members such that appropriate extension of the extendible members raises the platform from a buoyant to a partially-buoyant state, means for determining the position of the platform relative to the article, inspection means for inspecting the article, and a leg on which the inspection means is mounted, the leg being supported from the platform and being capable of extending below the platform. 2. Apparatus as claimed in claim 1, including a carriage from which the extendible leg is supported, first guide means, the carriage being located on and movable on the first guide means, and second guide means, the first guide means being located on and movable on the second guide means, the second guide means being disposed on the platform and aligned in a direction normal to the first guide means, thereby to provide x-y scanning of the inspection means relative to the article. 3. Apparatus as claimed in claim 1, wherein the support members are incorporated in a rack in which the article is locatable. 4. Apparatus as claimed in claim 3, wherein the extendible members have outwardly divergent conical lower ends and the support members have relieved upper ends. 5. Apparatus as claimed in claim 3, including radio means for linking the platform to a remote control station. 6. Apparatus as claimed in claim 1, including propulsion means on the platform, the propulsion means comprising a plurality of jets for ejecting the liquid therefrom below the surface of the liquid, and movable deflector means for deflecting the ejected liquid in a required direction so as to provide manoeuvrability of the platform. 7. Apparatus for locating a floatable platform relative to an article submerged in a liquid, the improvement comprising support members arranged to be adjacent to the article, extendible members depending from the platform, the extendible members being locatable on the support members such that appropriate extension of the extendible members raises the platform from a buoyant to a partially-buoyant state, means for determining the position of the platform relative to the article, the position determining means comprising laser means on the platform arranged to scan stationary coded targets remote from the platform, and a rack in which the support members are incorporated and in which rack the article is locatable. 8. Apparatus for locating a floatable platform relative to an article submerged in a liquid, the improvement comprising support members arranged to be adjacent to the article, extendible members depending from the platform, the extendible members being locatable on the support members such that appropriate extension of the extendible members raises the platform from a buoyant to a partially-buoyant state, means for determining the position of the platform relative to the article, a rack in which the support members are incorporated and in which rack the article is locatable, the article comprising a container for irradiated nuclear fuel.
059303190	summary	BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to a nuclear reactor with a propagation space for core melt, the propagation space being provided with a coolant conduit which leads to a coolant reservoir and which has a valve opening in a temperature-dependent manner. In a nuclear reactor of the above-mentioned type, which is known from German Published, Non-Prosecuted Patent Application DE 40 41 295 A1, a steel crucible disposed in a reactor pit receiving a reactor pressure vessel has a plurality of inner protective layers, in order to withstand the high temperature of the core melt. A coolant pipe leads in an upper half through a wall of the crucible and a melting plug is located at an end of the coolant pipe which is inside the crucible. Another end of the coolant pipe leads to a coolant reservoir. If core melt escapes from the reactor pressure vessel, it is intercepted directly below the reactor pressure vessel within the reactor pit. If the core melt rises level with an outlet orifice of the cooling conduit, the melting plug is melted open as a result of direct contact or as a consequence of heat radiation. Cooling water is thereby guided in a large quantity onto the surface of the core melt for the direct cooling of the latter. Indirect cooling of the core melt takes place through a cooling system disposed outside the crucible. Direct cooling does not commence until clearly after indirect cooling and leads to a rapid flooding of the crucible, in which case large quantities of cooling water can come into contact with the core melt. SUMMARY OF THE INVENTION It is accordingly an object of the invention to provide a nuclear reactor with a core melt propagation space provided with a coolant conduit leading to a coolant reservoir, which overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type and which allows early direct cooling of a core melt, flowing into a propagation space, over a region of large area. With the foregoing and other objects in view there is provided, in accordance with the invention, a nuclear reactor, comprising a coolant reservoir; a propagation space for core melt, the propagation space having a given cross-section; a spray conduit disposed in the propagation space, fed by the coolant reservoir and having a spraying area covering a large area of the given cross-section; and a device associated with the spray conduit and controlled for temperature-dependent opening when the core melt enters the propagation space. The cross-section of the propagation space can be spheroidal or polygonal (rectangular, hexagonal). The rapid, large-area spraying which takes effect from the outset gives rise to a crust on the core melt that appreciably reduces heat radiation. At the same time, an intercepting space above the crust fills with a steam atmosphere which drastically lowers the thermal load on the building structures, so that special protective layers (for example on the ceiling) can be avoided. As a result of the spraying of the core-melt surface, the water is distributed uniformly on the latter, thereby preventing water from infiltrating into the core melt and causing steam explosions. The crust, which becomes constantly thicker as a result of the spraying, acts in the same way, because it limits interactions between the core melt and water, that is to say, above all, it prevents steam explosions. In accordance with another feature of the invention, the spray conduit is disposed on the walls of the propagation or intercepting space, in such a way that it encloses the cross-section of the propagation or intercepting space. It can be fastened there in a simple way and, without further action, produces a large-area spray mist. In accordance with a further feature of the invention, the spray conduit is alternatively or additionally run at a distance from the bottom, over the cross-section of the propagation space. Such a configuration is provided, for example, in sprinkler systems in agriculture with pipelines running parallel to one another in order to cover a large area. For this purpose, it is possible to provide a multiplicity of spray conduits, which run parallel to one another or which intersect. In accordance with an added feature of the invention, in order to increase operating reliability, the spray conduit is a ring conduit having a plurality of feeds. It is advantageous for spraying to commence rapidly. In accordance with an additional feature of the invention, the device is a passively opening fitting which causes an opening of the coolant conduit, particularly in a temperature-dependent manner. In accordance with a concomitant feature of the invention, the device opening in a temperature-dependent manner is consequently disposed below the spray conduit, in such a way that a melting body keeping a sealing disc closed counter to the pressure of the coolant is located at the bottom of the propagation space. Other features which are considered as characteristic for the invention are set forth in the appended claims. Although the invention is illustrated and described herein as embodied in a nuclear reactor with a core melt propagation space provided with a coolant conduit leading to a coolant reservoir, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
	claims	1. A microfabricated mounting arrangement supporting at least one cylindrical electrode having a lengthwise axis, the arrangement comprising a substrate having a first and a second support member configured to support and connect electrically to the at least one electrode at a first and a second end thereof, the electrode being attached to the support member, and wherein at least a portion of one of the first and second support member is adapted to flex so as to allow movement of the attached electrode parallel to its lengthwise axis to compensate for thermal coefficient differences between the electrode and the substrate. 2. The arrangement of claim 1 wherein the movement of the at least partially moveable member is effected by suspending at least a portion of the moveable member relative to the substrate. 3. The arrangement of claim 1 wherein one of the first and second support members is at least partially moveable relative to the substrate and the other of the first and second support members is not moveable. 4. The arrangement of claim 1 wherein each of the first and second support members include an electrically conducting surface which, in use, is in electrical contact with the supported at least one electrode. 5. The arrangement of claim 1 wherein the substrate is an electrically insulating substrate. 6. The arrangement of claim 1 wherein each of the first and second support members are physically isolated from one another. 7. The arrangement of claim 1 wherein each of the first and second support members are electrically isolated from one another. 8. The arrangement of claim 1 wherein the substrate is an insulating substrate. 9. The arrangement of claim 8 wherein the insulator for the insulating substrate is formed from a glass or ceramic material. 10. The arrangement of claim 1 wherein each of the support members are formed from metal-coated silicon. 11. The arrangement of claim 1 wherein the at least partially moveable support member provides for relief in axial strain in the inserted cylindrical electrodes. 12. The arrangement of claim 1 wherein each of the support members are fabricated using at least one of the following processes:a) a lithographic process,b) an etching process,c) a deep reactive ion etching of silicon. 13. A microfabricated mount for a miniature electrostatic quadrupole, the mount including first, second, third and fourth mounting arrangements each as claimed in claim 1 and each configured to support a separately inserted electrode, and wherein the mounting arrangements are provided in two pairs, each pair sharing a common substrate, the quadrupole being formed by sandwiching the two substrates. 14. The mount of claim 13 wherein each of the two pairs of mounting arrangements are positioned relative to one another on their shared substrates such that when supported two similar inserted cylindrical electrodes mounted side by side on each of the two pairs have parallel axes. 15. The mount of claim 13 wherein the at least partially moveable support members are arranged in the geometry of a portal frame. 16. The mount of claim 13 including corresponding mating members provided on each of the two substrates, the mating members having mating surfaces which are brought into contact with one another on forming the sandwich structure, the height of the mating members defining the distance of each of the two substrates from one another. 17. The mount of claim 16 wherein the mating members are dimensioned such that when the sandwich structure is formed that inserted electrodes are encapsulated or shielded within the mating members. 18. The mount of claim 13, in which the two-substrate assembly is configured to hold four cylindrical electrodes in the geometry of one of:a) a quadrupole electrostatic lens,b) a mass filter,c) a linear quadrupole ion trap,d) a quadrupole ion guide. 19. A microfabricated mount for a miniature electrostatic quadrupole compnsing:a first and second insulating substrate, each substrate carrying at least four physically separated support members with electrically conducting surfaces arranged in two pairs, at least one element of each pair being partially suspended and flexible relative to the substrate; and wherein each pair of support members are configured to support and connect electrically to either end of a separate inserted cylindrical electrode having a lengthwise axis and which is attached to at least one end to the respective element, a flexing of the at least one element allowing a movement of the electrode attached thereto parallel to its lengthwise axis and relative to the substrate to compensate for thermal coefficient differences between the electrode and the substrate. 20. A microfabricated mount for a miniature electrostatic quadrupole as in claim 19, in which the partially suspended flexible elements are arranged in the geometry of a portal frame. 21. A microfabricated mount for a miniature electrostatic quadrupole as in claim 20, in which the portal frame consists of at least two suspended parallel beams, rigidly attached to the substrate at one end and linked together at the other by a rigid suspended element. 22. A microfabricated mount for a miniature electrostatic quadrupole as in claim 21, in which the rigid suspended element of the portal frame is used to support one end of a suspended cylindrical electrode. 23. A microfabricated mount for a miniature electrostatic quadrupole as in claim 19 configured to hold and support two similar inserted cylindrical electrodes with their axis parallel to and located in a trench formed in a further feature provided on the substrate. 24. A microfabricated mount for a miniature electrostatic quadrupole as in claims 23, in which the two substrates are assembled together and held parallel at a defined separation by contacting together the surfaces of the features containing the trenches. 25. A microfabricated mount for a miniature electrostatic quadrupole as in claim 23, in which the two features containing trenches combine to form a continuous conducting shield around the cylindrical electrodes. 26. A microfabricated mount for a miniature electrostatic quadrupole as in claim 19, in which the cylindrical electrodes are formed in a metal. 27. A microfabricated mount for a miniature electrostatic quadrupole as claim 26 in which the metal used for the cylindrical electrodes is stainless steel.
059075880	summary	BACKGROUND OF THE INVENTION Field of the Invention The invention relates to a device for collecting and cooling core melt from a reactor pressure vessel (RPV). It is, in particular, usable in the case of an EPR pressurized water reactor. German Published, Non-Prosecuted Patent Application DE 43 19 094 A1, corresponding to International Publication WO 94/29876 and U.S. application Ser. No. 08/569,676, filed Dec. 8, 1995, now U.S. Pat. No. 5,867,548, discloses a device for collecting and cooling core melt from an RPV, in which a prechamber that is connected through a channel to a spreading chamber, is disposed below the RPV. On the reactor side, the channel has a barrier wall or separating wall which is destroyed by the core melt within a predetermined time after the core melt has arrived. The prechamber is constructed approximately frustoconically and is bounded at the bottom by a refractory concrete base which serves somewhat as a crucible. The concrete base should be made of a refractory ceramic or special bricks. In that case, when the material alloys with the core melt the effect of the material is preferably to reduce the melting point, with the result that it makes the core melt less viscous. The bottom of the spreading chamber is lined with a heat-resistant material. German Patent DE 43 06 864 C2 discloses a safety configuration for a nuclear reactor, in which a collection device for the core melt is disposed below the reactor pressure vessel. In that case the collection vessel is a structure made of cast elements of cast iron and/or cast steel, which forms an outflow system for the core melt. The collection device in that case corresponds, in comparison to the above-mentioned prior art, to the spreading chamber located therein, which is disposed laterally next to the RPV in that device. In that configuration, no prechamber is provided. The purpose of the collection device is clearly to cool the collected core melt in an accumulation chamber. In the case of a core melt gradually flowing downwards, plugging of the supply channels can possibly occur as a result of excessive cooling. Additional cooling is prevented in that way, as a result of which further damage can possibly occur. German Published, Prosecuted Patent Application DE-AS 22 34 782 discloses a reactor core vessel, in which a receptacle for collecting the core in the event of a core meltdown is disposed below fuel elements. In order to provide cooling, the receptacle is constructed in such a way as to be ribbed in the manner of a heat sink on the side remote from the core and is in contact with the water of a coolant circuit. The core melt can be cooled in this way. The receptacle is disposed inside the RPV in this case. SUMMARY OF THE INVENTION It is accordingly an object of the invention to provide a device for collecting and cooling core melt from a reactor pressure vessel, which overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices of this general type and which achieves improved flow of the core melt into its spreading chamber. With the foregoing and other objects in view there is provided, in accordance with the invention, a device for collecting core melt from a reactor pressure vessel, comprising a prechamber disposed below the reactor pressure vessel; a spreading chamber disposed laterally next to the reactor pressure vessel for receiving the core melt; a channel connecting the spreading chamber to the prechamber; and a base unit forming a bottom region at least of the prechamber, the base unit made of a material having such a high thermal conductivity that a crust forms after arrival of the core melt on the base unit. In this way, the core melt first of all forms a crust on the base unit which acts as an autogenous crucible. The base unit is thereby initially protected from damage. This is achieved by virtue of the good heat dissipation of the base unit. The autogenous crucible has an insulating effect on the remaining core melt, so that the latter at first maintains its consistency (liquid). After a barrier wall has been opened, the core melt then flows continuously or constantly into the spreading chamber. The intention in this case is for all of the core, as far as possible, to flow at once out of the prechamber into the spreading chamber. In accordance with another feature of the invention, the base unit is made of metal. The desired thermal conductivity is thereby produced, which leads to good crust formation. In accordance with a further feature of the invention, the base unit is composed of subunits. The device is thereby easy to transport and simple to install. In accordance with an added feature of the invention, the base unit is constructed on the prechamber side in the manner of a crucible. A container structure is thereby obtained which allows favorable thermic handling of the core melt. In accordance with an additional feature of the invention, the base unit has a cooling device. Melting of or damage to the base unit is thereby prevented. Long-term thermal overloading is additionally prevented. In accordance with yet another feature of the invention, at least the prechamber, and optionally the channel, is filled with packing units. Additional stress on the prechamber due to a steam explosion is thereby likewise avoided. In accordance with yet a further feature of the invention, the bottom surfaces of the channel and/or the spreading space are formed by cooled bottom elements. Good dissipation of the residual heat is possible in this way. Such bottom elements can be laid easily and additionally provide equalization in the event of temperature fluctuations. In accordance with yet an added feature of the invention, in order to provide good sealing with regard to the coolant, the bottom elements have tongue and groove connections or a stepped connection at their connection points or locations. In accordance with a concomitant feature of the invention, there is provided a flexible seal interposed between the bottom elements. This provides a good mechanical connection and liquid leak-tightness. Other features which are considered as characteristic for the invention are set forth in the appended claims. Although the invention is illustrated and described herein as embodied in a device for collecting core melt from a reactor pressure vessel, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims. The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
	description	This application claims the benefit of U.S. Provisional Application No. 61/623,332, filed Apr. 12, 2012. U.S. Provisional Application No. 61/623,332, filed Apr. 12, 2012 is hereby incorporated by reference in its entirety into the specification of this application. The following relates to the nuclear power reactor arts, neutron reflector arts, and related arts. In a nuclear reactor, fissile material is arranged in the reactor such that the neutron flux density resulting from fission reactions is sufficient to maintain a sustained fission process. In a commercial reactor, fissile material is typically provided in the form of fuel rods mounted in modular, elongated fuel assemblies which are generally square or hexagonal in cross section. A plurality of such fuel assemblies are arranged together to form a reactor core which is contained inside a cylindrical stainless steel core basket. This entire assembly, in turn, is mounted inside a pressure vessel. In a typical configuration, reactor coolant flows downward in an annular space between the core basket and the pressure vessel, reverses direction in a lower plenum of the vessel, flows upward through openings in a lower end plate at the bottom of the reactor core, and upward through the fuel assemblies where it is heated by the reactor core. The heat extracted by the reactor coolant from the core is utilized to generate electricity thereby lowering the temperature of the reactor coolant which is recirculated through the reactor in a closed loop. In boiling water reactor (BWR) designs, the primary coolant boils inside the pressure vessel and the resulting primary coolant steam is piped through a recirculating loop to drive a turbine. In pressurized water reactor (PWR) designs the primary coolant remains in a subcooled liquid state and heats secondary coolant in an external steam generator, and the secondary coolant drives a turbine. In a variant PWR design, the steam generator is located inside the pressure vessel (i.e., an integral PWR) and a secondary coolant circuit flows into the pressure vessel to feed the steam generator. In the fission process, free neutrons are generated. In a thermal nuclear reactor, these neutrons are slowed, i.e. thermalized, by ambient water which is advantageous as thermalized neutrons are more likely to stimulate additional fission events as compared with faster neutrons. However, neutrons originating near the outer boundary of the reactor core may travel outside the reactor core and be lost. To improve overall efficiency and to increase burn rate for the outer fuel assemblies, it is known to include a core former, or radial reflector, between the reactor core and the core basket. The objective is to reflect neutrons traveling out of the core back toward the core to enhance burn of the fuel assemblies. The welds, bolts, or other fasteners of the radial reflector experience high radiation flux, and can be prone to damage or failure due to the harsh operating environment with the reactor. Repair of any such damage is difficult or impossible due to the extremely radioactive environment. Moreover, the radial reflector can impede natural circulation around the reactor core, which may be problematic for any emergency core cooling system (ECCS) that relies upon natural circulation. In some instances radial reflectors are known to cause jetting of coolant laterally onto the fuel assemblies. Jetting is generally undesirable as excessive wear may result over time. According to one aspect, an apparatus comprises a nuclear reactor core comprising fissile material and a core former surrounding the nuclear reactor core. The core former comprises one or more single-piece annular rings wherein each single-piece annular ring comprises neutron-reflecting material. In some embodiments the core former comprises a stack of two or more single-piece annular rings wherein each single-piece annular ring comprises neutron-reflecting material. In some embodiments the stack of single-piece annular rings is self-supporting. In some embodiments the stack of single-piece annular rings does not include welds or fasteners securing adjacent single-piece annular rings together. According to another aspect, an apparatus comprises a nuclear reactor core comprising fissile material, a core former surrounding the nuclear reactor core and including one or more single-piece annular rings wherein each single-piece annular ring comprises neutron-reflecting material, and a core basket containing the nuclear reactor core and the core former. In some embodiments an annular gap is defined between the core former and the core basket. In some embodiments an annular gap is defined between the core former and the core basket and the core former comprises a self-supporting stack of single-piece annular rings wherein each single-piece annular ring comprises neutron-reflecting material. In some embodiments the outer surface of the core former includes axially extending channels. In some embodiments the core former does not include welds and does not include fasteners. According to another aspect, a method comprises: constructing a core former by stacking a plurality of single piece annular rings wherein each single piece annular ring comprises neutron-reflecting material; and loading a nuclear reactor core inside the core former by disposing fuel assemblies comprising fissile material inside the core former. In some embodiments the method further includes, after the constructing and loading, operating a nuclear reactor comprising primary coolant disposed in a pressure vessel that also contains the constructed core former and loaded nuclear reactor core in order to heat the primary coolant. In some embodiments the method further comprises forging each single-piece annular ring. In some embodiments the method further comprises casting each single-piece annular ring. In some embodiments the method further comprises rolling and welding one or more plates to form each single-piece annular ring With reference to FIGS. 1-3, a core former as disclosed herein is described in the context of an illustrative nuclear reactor of the pressurized water reactor (PWR) type. The nuclear reactor includes a pressure vessel 10, only a lower portion of which is shown diagrammatically in phantom in FIG. 1. The lower portion of the pressure vessel contains a reactor core constructed as an array of fuel assemblies. For illustrative purposes, FIG. 1 shows a single fuel assembly 12 being loaded into the reactor. (The loading is done using a crane or other lifting apparatus, not shown). The fuel assembly 12 is shown diagrammatically, and typically includes a structural skeleton of spacer grids and upper and lower end fittings or nozzles supporting the fuel rods with guide tubes interspersed amongst the fuel rods to provide conduits for control rods, instrumentation, or the like (details not illustrated). FIG. 3 shows an overhead or top view including the complete nuclear reactor core 14 constructed as an array of fuel assemblies 12. The illustrative reactor core of FIG. 3 includes 69 fuel assemblies, but more or fewer fuel assemblies can be included depending upon the size of the core and the sizes of the constituent fuel assemblies. The illustrative fuel assemblies 12 are all of equal size, and the layout of the fuel assemblies in the reactor core can be varied. The reactor core 14 is contained in a core former 16 which in turn is contained in a core basket 18. The reactor core 14 can have substantially any configuration compatible with a light water reactor. In the illustrative configuration shown in FIG. 3, the reactor core includes 69 PWR type fuel assemblies each having a 17×17 array of fuel rods supported by a bottom grid structure that is part of a core former 16. The upper portion of the nuclear reactor is not shown, but typically includes a hollow cylindrical central riser defining an inner cylindrical plenum conducting primary coolant exiting from the top of the reactor core 14 upward. This is sometimes called the “hot leg” of the primary coolant circuit. A downcomer annulus is defined between the central riser and the pressure vessel 10, and provides the downward flowing “cold leg” of the primary coolant circuit which returns primary coolant to the bottom of the nuclear core 14. The reactor optionally includes other components such as internal steam generators, a reactivity control sub-system including control rods coupled with external or internal control rod drive mechanisms (CDRM), an optional internal pressurizer, and so forth. Other vessel configurations and reactor types are also contemplated, including PWR designs with external steam generators, integral PWR designs with steam generators disposed inside the pressure vessel, various BWR designs, and so forth. The core former 16 provides lateral support of the fuel assemblies and is constructed as a stack of single-piece annular rings 24. Each annular ring is a single-piece component, for example a single-piece forged or cast stainless steel ring. A single-piece may also be formed by rolling and welding one or more plates. Each annular ring is suitably a monolithic element without joints or seams. The stack of annular rings 24 is optionally a self-supporting stack, with the upper end of each ring supporting the lower end of the next-higher ring in the stack. On the other hand, if the reactor core is of sufficiently low profile it is contemplated to employ as few as a single annular ring in constructing the core former. In FIG. 1, the illustrative core former 16 is shown concentrically arranged with core basket 18 (e.g., a lower shroud), a portion of the core basket 18 being removed in FIG. 1 to expose the core former 16 for purposes of illustration. FIG. 4 illustrates a top view of a single core former ring 24. The core former ring 24 is an annular element having a cylindrical outer surface 28 and an inner 32 shaped to conform with the outer periphery of the reactor core 14 (see also FIG. 3). More generally, the outer surface 28 should conform with the inner surface of the core basket, which is cylindrical in the case of illustrative core basket 18. With particular reference to FIGS. 1 and 2, in the axial direction, that is, the direction transverse to the plane of the annular ring 24, the number of rings 24 in the stack is sufficient for the core former 16 to be at least coextensive with the axial extent of the reactor core 14. Said another way, the “height” of the core former 16 should be equal to or greater than the “height” of the reactor core 14 that is placed within the core former 16. Advantageously, the core former 16 does not include any welds, bolts, or other fasteners. Rather, the stack of annular rings 24 is self-supporting. For manufacturing convenience, it is advantageous for the rings 24 of the stack to be interchangeable. However, in some embodiments the uppermost ring and/or the lowermost ring may be different. By way of illustrative example, the core former 16 includes five annular rings 24, of which the three middle single-piece annular rings 24 are interchangeable, the lowermost ring 24″ omits any bottom-surface features intended to mate with a “further-below” ring (since it is not aligning with a ring located below it) and the uppermost ring 24U similarly omits any upper-surface features intended to mate with a “further-above” ring. Additionally, the uppermost ring 24U includes pins 36 on the upper surface for lateral and rotational alignments of components, such as upper internals, located above the uppermost ring 24U. Additional pins or other core former retention features may be included to keep the rings from moving vertically. In some embodiments the weight of the annular rings 24, either alone or in combination with the weight of components located above the uppermost ring 24U, may be sufficient to prevent vertical movement, in which case no mounting or retention features are needed. As noted, the radially inner surface 32 of each ring 24 conforms to the shape of the core (e.g., plurality of fuel assemblies 12) and the radially outer surface 28 is cylindrical or otherwise shaped to conform with the inner surface of the core basket 18. In some embodiments there is a relatively small gap (e.g., annular, flow passage) defined between the outer surface 28 of the core former 16 and the inner diameter or surface of the core basket 18 for the circulation of water. This gap serves as a thermal sleeve, and also allows bypass flow outside of the core which can be useful in some emergency core cooling system designs. In one embodiment, gamma heating increases the temperature of the core former rings 24 and bypass flow provides cooling. The thermal sleeve functionality helps accommodate the thermal difference from the hot leg to the cold leg of the nuclear reactor cooling system, and reduces stresses within the core former 16 that can be generated because of such thermal gradient. The flow bypass functionality is useful in the event of a loss of primary coolant flow, as the thermal sleeve also acts as a bypass flow channel, allowing water to travel in a natural circulation loop vertically downwards through the thermal sleeve, exit the core former 16 at the bottom, and turn and enter the core where it exits the top of the core and again turns and enters the thermal sleeve to repeat the loop. During normal operation, the bulk of the primary coolant flow enters the bottom of the core former 16 and flows upward through the reactor core 14, and only a small portion of the total flow travels upward through the thermal sleeve. Optionally, more bypass flow can be provided (or the amount of bypass flow can be designed) by increasing the size of the thermal sleeve or by providing bypass flow slots or channels 40 in the outer surfaces 28 of the rings 24 of the core former 16. In the stack of rings, these channels 40 extend the entire axial length of the core former 16 to allow more bypass flow in addition to the thermal sleeve. The size, shape, and location of these slots can be chosen to provide a desired level of bypass flow. Instead of or in addition to the bypass flow slots 40 on the outside surface 28 of the core former 16, one or more holes could be drilled axially through the stack of core former rings. The core former 16 and the reactor core 14 are disposed in the core basket 18. In the illustrative embodiment, the core basket 18 is suspended from a mid-flange 44 (indicated diagrammatically in FIG. 1) of the pressure vessel 10 by mounting brackets 42. Other arrangements are also contemplated, including support of the core basket from below, e.g. by feet or pedestals resting on a lower surface of the pressure vessel. The core former 16 is intended to act as a neutron reflector. (Said another way, the core former 16 can alternatively be considered to be a neutron reflector 16). Toward this end, the annular rings 24 of the core former 16 are made of stainless steel or another suitable corrosion resistance neutron reflective material in order to provide neutron reflection so as to more efficiently burn the fuel in the periphery fuel assemblies. The lack of welds, bolts or other threaded fasteners, or the like in some embodiments is advantageous as welds or fasteners can suffer failures due to irradiation embrittlement and differential thermal expansion created from the radiation and heat output by the reactor core 14. In addition, the core former 16 has few components, e.g. five rings 24 in the illustrative core former 16 and optional additional components such as the illustrative upper constraint pins 36. While five annular rings 24 are employed in the illustrative core former 16, other numbers of rings (down to as few as a single ring) can be arranged or stacked axially to produce a core former of a desired height. The quantity, size, and geometry of each of the rings can vary to create a wide range of core formers. Adjacent rings can include mating features on for interlocking and/or restricting radial and/or axial movement between the rings. For example, the as seen in FIGS. 2 and 4, adjacent rings can be keyed together by a key/keyway interlocking configuration 50 to prevent relative rotation between adjacent rings. In some embodiments, the stack of single-piece annular rings 24 is self-supporting. However, it is alternatively contemplated to include lateral support, for example via the surrounding core basket, in order to prevent the stack from leaning or to provide load transfer from the core basket into the core former or from the core former to the core basket. With reference to FIG. 4 and with further reference to FIG. 5, mating surfaces of adjacent rings 24 of the stack can include an annular joint 60 that provides a tortuous path for (lateral) fluid flow into or out of the core former 16 via the joints between the rings 24. FIG. 5 shows a side sectional view of a portion of a ring 241 and a ring 242 stacked on top of the ring 241. As seen in FIG. 5, the top surface of the lower ring 241 includes a circumferential groove or recess 62 that mates with a circumferential protrusion 64 on the bottom surface of the upper ring 242. FIG. 5 shows the upper surface of one of the rings 24 including the circumferential groove or recess 62. (The circumferential protrusion 64 is on the bottom surface of the ring 24 and hence is not visible in FIG. 4). This configuration forms the illustrative annular joint 60 in the form of a shiplap joint that provides enhances alignment of the rings in the stack while also reducing leakage through the interface between the rings. The joint configuration further inhibits coolant from flowing between adjacent rings and subsequently spraying or otherwise jetting into the fuel assemblies. The lowermost ring 24L of the stack omits the circumferential protrusion 64 (since there is no further-below ring with which to mate), and similarly the uppermost ring 24U omits the circumferential groove or recess 62. Other suitable annular joints providing the desired tortuous flow path through the joint include mating grooves/protrusions. The illustrative core former 16 surrounds the entire height of the reactor core 14, but is still contained within the core basket 18. The core former 16 in one embodiment is made of stainless steel to reflect neutrons that leave the core region back into the core to continue the nuclear reaction. The rings comprising the core former 16 can be forged or cast, for example. As mentioned, one preferred material is stainless steel. The rings can have a wide range of radial thicknesses. The thickness should be chosen to provide adequate neutron reflection, and should also be sufficient to ensure structural integrity of the stack of annular rings 24. A relatively thicker core former may be used to enhance burn-up of the periphery fuel assemblies, for example in the context of a small modular reactor (SMR) having a relatively small core, and/or in the context of a reactor design intended for operation without performing occasional fuel shuffling. More generally, the disclosed core former designs are suitable for use in nuclear reactors of any size, and are suitable for use in conjunction with fuel shuffling or without fuel shuffling. The term “fuel shuffling” refers to the process of occasionally shutting down the reactor and moving fuel assemblies to different locations within the reactor core so that the fuel in each fuel assembly is more thoroughly consumed than would be the case if each fuel assembly remained in a single location within the reactor core for the entire useful life of the fuel. The exemplary embodiments have been described with reference to the preferred embodiments. Obviously, modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the exemplary embodiment be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
061119288	description	DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT The numeral 10 generally designates a typical prior art annular canopy seal weld configuration between a control rod drive mechanism nozzle 12 of a reactor vessel head (not shown) and a mating part 14. The mating part 14 could be a spare capped CRDM, a core exiting thermocouple nozzle assembly or a CRDM housing. It mates with a nozzle flange 18. A canopy seal 16, called an "omega seal" because of its shape, is described in U.S. Pat. No. 5,631,936 assigned to the same assignee as the instant application. The omega seal of that patent is a flexible graphite seal, although the configuration of the canopy seal of the instant arrangement is different in that it is on the top of the nozzle 12 and requires that the applied seating pressure comes from a compressing top plate of the novel top mount canopy seal mechanical clamp assembly of the invention generally designated 20 rather than from the housing 14 (or cap) itself. The top mount canopy seal mechanical clamp assembly (TM-CSCA) 20, as seen in FIG. 2, is made of stainless steel and is designed to repair leaking in the canopy seal 16 weld. This weld, and thus seal 16, has a tendency to develop cracks as a result of mechanical stress and/or stress corrosion cracking. These cracks propagate through the weld wall until leakage occurs. The TM-CSCA 20 is a non-welded mechanical method of stopping leakage in the canopy seal weld 16. The TM-CSCA 20 seals the leaking weld 16 and introduces a compressive load into the canopy seal, which tends to close and arrest the crack propagation. The TM-CSCA 20 seals the leaking weld by compressing a flexible graphite seal 22 over the entire annular seal weld area 16 as shown in FIG. 2. The flexible graphite seal material is preferably GRAFOIL.RTM. available from the Union Carbide Corporation. The TM-CSCA 20 has an annular housing 24 which is lowered below the flange 18 of nozzle 12. Housing 24 has a radially inwardly directed flange 26 of such dimension as to permit it to telescopically pass the nozzle flange 18 having the canopy seal weld 16. Insert support halves 28 and 30 are lowered and placed in the housing 24 one at a time. The halves 28 and 30 are of semi-annular shape and are seated concentrically with an annular shoulder 32 thereof in face to face engagement with an axially facing inner surface of the annular hollow housing flange 26. An annular top plate 34 of stainless steel is placed in register concentrically with the annular hollow housing 24 and surrounds the annular canopy 10. A seal seat 36 is provided in top plate 34 over and radially outward of canopy seal 16. An annular seal support ring 38 fits in a slot 40 in top plate 34 to confine the flexible graphite seal 22 over the annular seal weld area 16. The slot 40 is deeper than the width of ring 38 to permit movement of top plate 34 relative to insert support halves 28 and 30 by means of cap screws 42 engaging threaded bores 44 in housing 24. In this way cap screws 42 can draw the top plate 34 and housing 24 together to create compressive force on the flexible graphite seal 22 against canopy seal weld 16 to create a flexible graphite leak stopping seal at the weld 16. The cap screws 42 are provided with Belleville washers 46 between their heads and the top plate 34 to provide and maintain the necessary retaining loading force.
	abstract	A control rod assembly for a nuclear reactor having a reactor core and a pressurized fluid source, including a control rod disposed within a control rod sleeve, a lead screw that is selectively secured to the control rod, a trip latch that is secured to a bottom end of the lead screw, the trip latch being selectively securable to a top end of the control rod, a control rod drive motor that is operably connected to the lead screw, and a valve that is in fluid communication with the pressurized fluid source of the nuclear reactor and is movable between a first position and a second position, wherein in the second position of the gas valve the trip latch is in an open position.
	description	1. Field of the Invention The present invention relates to an observation method and equipment that use an ultrasonic reflected wave within a liquid or a solid. 2. Description of the Related Art An ultrasonic observation technique is used for inspection of a structure or the like in water and non-destructive inspection of the inside of a solid (steel material or the like). It is one of techniques for transmitting an ultrasonic wave to an object to be observed and visualizing a change in a physical amount of the object based on a wave reflected from the object to be observed. For example, inspecting objects to be observed in water (such as a river and an ocean) involves attachment of observation equipment for inspection to a ship or a remotely-operated vehicle. In non-destructive testing, an operator may physically hold the observation equipment or attach it to an automated scanner to perform the inspection. In both cases above, means, which could be an operator or an automated device such as a remotely-operated vehicle or an automated scanner, for transporting the observation equipment to an object to be observed is required. If the object to be observed is small but the volume of the observation equipment is large, an observation operation may be limited. That case then needs the observation equipment to be downsized. As one of downsized equipment an ultrasonic inspection device, which is downsized as much as possible and is high-sensitive, is known (refer to, for example, JP-2005-127870-A). As disclosed in JP-2005-127870-A, two methods are available for a case in which a phased array ultrasonic inspection device is used to remotely observe a cramped portion. The first method is to cause only an array transducer to approach a place located near the portion to be observed. In this method, a multicore coaxial cable that connects the array transducer to a transceiver is required to be longer. In order to suppress signal attenuation due to the length of the cable, a large-diameter and heavy multicore coaxial cable needs to be used. This case will increase a load to be applied to the means, the operator or scanner, for transporting observation equipment. On the contrary, taking precedence in a reduction in the weight of the cable will necessitate the cable to be thinner. The thinner cable will make the signal attenuation greater, which will impede the ensuring an excellent signal-to-noise ratio (SN ratio) in receiving wave of an ultrasonic wave. The second method is to cause the array transducer and the transceiver to approach a place near the object to be observed. In order to cause the transceiver to approach the cramped portion to be observed, the transceiver needs to be downsized. In general, the transceiver requires an electric circuit for transmitting and receiving a signal and an electric circuit for executing a complex process such as delay control, and therefore, the downsizing of the transceiver is limited. In addition, a tradeoff, which leads to a reduction in the resolution of an ultrasonic image, could occur instead of the downsizing although the transceiver can be smaller by reducing the number of transducer elements in the array transducer that can be used for the circuit. It has traditionally been difficult to use an ultrasonic wave to visualize an object to be observed located at a cramped portion while maintaining the quality of an ultrasonic image. An object of the invention is to provide ultrasonic observation equipment, an ultrasonic observation system, and an ultrasonic observation method that enable an object that is to be observed located at a cramped portion to be visualized using an ultrasonic wave while maintaining the quality of an ultrasonic image. In order to accomplish the aforementioned object, ultrasonic observation equipment includes a pulsar configured to generate a pulse wave, a single element ultrasonic sensor for transmitting including a single transducer element and configured to transmit an ultrasonic wave on the basis of the pulse wave, an ultrasonic array sensor for receiving including a plurality of transducer elements and configured to receive an ultrasonic reflected wave, a receiver configured to receive electric signals from the transducer elements included in the ultrasonic array sensor, an amplification and conversion unit configured to amplify the electric signals received by the receiver from the transducer elements included in the ultrasonic array sensor, convert the electric signals into digital signals, and arrange the digital signals in a serial order so as to generate a serial digital signal, and an image generator configured to generate an image on the basis of the serial digital signal. According to the invention, an object to be observed located at a cramped portion can be easily visualized with the use of an ultrasonic wave while the quality of an ultrasonic image is maintained. Objects, configurations, and effects other than those described above are clarified through a description of the following embodiments. Hereinafter, a configuration and operations of an ultrasonic observation system 100 that includes ultrasonic observation equipment 10 according to a first embodiment of the invention are described with reference to FIGS. 1 to 7. In the first embodiment, the ultrasonic observation equipment 10 uses an ultrasonic wave to observe a pipe included in a nuclear reactor as an example. For inspection of the inside of the reactor of a nuclear power plant, a structure to be inspected and included in the reactor is under water as an example. First, an overall configuration of the ultrasonic observation system 100 that includes the ultrasonic observation equipment 10 according to the first embodiment of the invention will be described with reference to FIG. 1. FIG. 1 is a diagram illustrating the configuration of the ultrasonic observation system 100 that includes the ultrasonic observation equipment 10 according to the first embodiment of the invention. Hereinafter, the same parts are denoted by the same reference numerals. The ultrasonic observation system 100 is mainly constituted of the ultrasonic observation equipment 10. The ultrasonic observation equipment 10 includes an ultrasonic sensor 101, a small ultrasonic transceiver 102, a processing unit 103, a display unit 104, and a traveling mechanism control device 105 (or a relay unit 105). Details of a configuration of the ultrasonic observation equipment 10 will be described later with reference to FIG. 3. The nuclear reactor includes a reactor pressure vessel 501, a shroud 502, and an incore structure 508 as objects to be observed by the ultrasonic observation equipment 10. Representative examples of the incore structure are a control rod driving housing (CRDH) stub tube extending through a bottom portion of the reactor pressure vessel 501, a stub tube for control rod driving system, an incore monitoring housing (ICMH) tube, and a shroud support. For example, the CRDH and the ICMH are each composed of approximately 100 tubes or more placed close to each other in the reactor pressure vessel with a radius of approximately 7 meters. Thus, the objects to be observed are located in a cramped space (or at a cramped portion). The ultrasonic sensor 101 and the small ultrasonic transceiver 102 are mounted on the underwater traveling mechanism 509. The processing unit 103, the display unit 104, and the traveling mechanism control device 105 are arranged on an operating floor 503 placed in an air environment. An operation carriage 504 is used to suspend the underwater traveling mechanism 509 by use of a composite cable 506A under water in the reactor, the underwater traveling mechanism 509 having the ultrasonic sensor 101 and the small ultrasonic transceiver 102 mounted thereon. The composite cable 506A is configured to include a cable 506 to be used to control the traveling mechanism, a cable 507 for the ultrasonic observation equipment, and a high-strength resin string, for example. The composite cable 506A is configured to include the cable 506 and the cable 507 that have different cable cores, for example. The cables 506 and 507 that are constituent elements of the composite cable 506A may use the same optical fiber through which a signal is transferred in serial form. A configuration of the underwater traveling mechanism 509 included in the ultrasonic observation equipment 10 according to the first embodiment of the invention will now be described with reference to FIG. 2. FIG. 2 is an enlarged view of the underwater traveling mechanism 509 included in the ultrasonic observation equipment 10 according to the first embodiment of the invention. The underwater traveling mechanism 509 includes the ultrasonic sensor 101, the small ultrasonic transceiver 102, an optical camera 509A, and an underwater movement promoting mechanism 509B. As illustrated in FIG. 2, the ultrasonic sensor 101 is provided with the underwater traveling mechanism 509 in such a manner as to observe an object with an ultrasonic wave in a direction D2 (for example, a front side of the underwater traveling mechanism 509) parallel to a direction D1 in which the optical camera 509A of the underwater traveling mechanism 509 observes an object. The ultrasonic sensor 101 and the small ultrasonic transceiver 102 are integrated with each other, for example, in order to downsize the equipment. The small ultrasonic transceiver 102 is connected to the traveling mechanism control device 105. The traveling mechanism control device 105 buffers received digital data in a storage unit of the traveling mechanism control device 105. A communication unit 105A of traveling mechanism control device 105 communicates with the processing unit 103. A personal computer may be used instead of the traveling mechanism control device 105. A configuration of the ultrasonic observation equipment 10 according to the first embodiment of the invention will now be described with reference to FIG. 3. FIG. 3 is a block diagram illustrating the ultrasonic observation equipment 10 according to the first embodiment of the invention. The ultrasonic observation equipment 10 includes the ultrasonic sensor 101, the small ultrasonic transceiver 102, the processing unit 103, the display unit 104, and the traveling mechanism control device 105 serving as the relay unit. The traveling mechanism control device 105 may not be installed, and the small ultrasonic transceiver 102 and the processing unit 103 may communicate directly with each other. The ultrasonic sensor 101 for transmission and reception includes a single element ultrasonic sensor for transmitting 101A and an ultrasonic array sensor for receiving 101B. The single element ultrasonic sensor for transmitting 101A includes a single transducer element. The ultrasonic sensor 101B includes a group of minute transducer elements regularly arranged in an array. The single transducer element of the single element ultrasonic sensor for transmitting 101A generates a single ultrasonic wave in accordance with a voltage applied. The single element ultrasonic sensor for transmitting 101A, however, may have a plurality of transducer elements connected in parallel to each other, and the same voltage may be applied to the single element ultrasonic sensor for transmitting 101A. The single element ultrasonic sensor for transmitting 101A is displaced and generates an ultrasonic wave on the basis of a high-voltage electric signal (a high-voltage pulse wave of 100V, for example) transmitted from a pulsar 102A. In addition, the ultrasonic array sensor for receiving 101B converts displacements caused due to received weak ultrasonic waves into electric signals and transmits the electric signals to a receiver 102B. The small ultrasonic receiver 102 includes the pulsar 102A, the receiver 102B, an amplification and conversion unit 102D, a power source 102C, and a communication unit 102E. The pulsar 102A is connected to the single element ultrasonic sensor for transmitting 101A. The receiver 102B is connected to the ultrasonic array sensor for receiving 101B. The amplification and conversion unit 102D amplifies received electric signals and executes analog-to-digital conversion so as to convert the amplified electric signals into digital signals. The communication unit 102E transfers a trigger signal (such as rectangular pulse wave) to be used to control the timing of the generation of the high-voltage pulse wave to be supplied from the pulsar 102A for the generation of an ultrasonic wave and transfers the digital signals converted from the received wave by the amplification and conversion unit 102. The power source 102C supplies power to these constituent elements 102A, 102B, 102D, and 102E. The processing unit 103 includes an image generator 103A, a storage unit 103B, and a communication unit 103C. The image generator 103A generates an ultrasonic image from the digital signals of the received wave. The image generator 103A causes the generated ultrasonic image to be stored in the storage unit 103B. The communication unit 103C communicates with the communication unit 102E of the small ultrasonic transceiver 102 through the relay unit 105. The communication unit 103C transmits the ultrasonic image generated by the image generator 103A to the external display unit 104. The external display unit 104 includes a display unit 104A, a user interface 104B (input unit), and a communication unit 104C. The external display unit 104 displays image data of the received wave on the display unit 104A. A user uses the user interface 104B (input unit) to operate the ultrasonic observation equipment 10. The communication unit 104C receives the image data transmitted from the communication unit 103C of the processing unit 103. The communication unit 104C transfers a control command (such as an instruction to transmit an ultrasonic wave and an instruction to record the received wave) input through the user interface 104B operated by the user. The control command (control signal) is input from the user interface 104B of the external display unit 104 and transferred through the processing unit 103 and the relay unit 105 to the small ultrasonic transceiver 102. The communication at this time is executed wirelessly or through cables by the communication units (102E, 105A, 103C, and 104C). The processing unit 103 may communicate with the external display unit 104 through the relay unit 105. The relay unit 105 includes a communication unit 105A and a storage unit 105B. The relay unit 105 causes received digital data to be buffered in the storage unit 105B and communicates with the processing unit 103 and other units through the communication unit 105A. A wireless relay unit provided with a function such as a hub or other control devices to be used with the ultrasonic observation equipment may be used as the relay unit 105. Communication between the relay unit 105 and the small ultrasonic transceiver 102, and communication between the relay unit 105 and the processing unit 103 are each wireless or by way of a cable. A configuration of the ultrasonic sensor 101 included in the ultrasonic observation equipment 10 according to the first embodiment of the invention will now be described with reference to FIG. 4. FIG. 4 is a diagram illustrating the configuration of the ultrasonic sensor 101 included in the ultrasonic observation equipment according to the first embodiment of the invention. The ultrasonic sensor 101 for transmission and reception includes the single element ultrasonic sensor for transmitting 101A and a receiving array sensor divided into two sensors 101B1 and 101B2. The receiving array sensors 101B1 and 101B2 each have a transducer element group. In FIG. 4, an X axis represents a direction in which the transducer elements that form the receiving array sensors are arranged, a Y axis represents a direction perpendicular to the X axis in a plane in which the transducer elements are arranged, and a Z axis represents a normal of the elements (for transmission and reception). It is assumed that the directions of the coordinate axes are defined in the same manner in FIG. 4 and later. An acoustic field 702A of an ultrasonic wave transmitted is formed to be spread from the single element ultrasonic sensor for transmitting 101A. In order to spread the acoustic field, there are a method for spreading a beam in a directivity angular range θ (θ∝λ/D, where λ is a wavelength of the ultrasonic wave) from the elements with a dimension D reduced, a method for diffusing an acoustic field with the use of an acoustic lens, and other methods. In the example illustrated in FIG. 4, the dimension D in the X axis direction is reduced, and a spreading angle of the beam is increased. However, a dimension of the elements in the Y axis direction may be reduced, while the spreading angle of the beam is increased. An acoustic field 701C of a wave to be received by the ultrasonic array sensor for receiving 101B (including the receiving array sensors 101B1 and 101B2) is formed so as to spread in the direction (X axis direction) in which the elements of the array are arranged. A range in which the ultrasonic wave can be imaged is a region 704 in which the acoustic field 702A of the ultrasonic wave transmitted overlaps the acoustic field 701C of the ultrasonic wave to be received. Accordingly, the region 704 in which the acoustic fields 702A and 701C intersects with each other only needs to be widened in order to increase the range in which the ultrasonic wave can be imaged. For example, the single element ultrasonic sensor for transmitting 101A and the ultrasonic array sensor for receiving 101B (including the receiving array sensors 101B1 and 101B2) are arranged in such a manner that the position 703 of the center of the single element ultrasonic sensor for transmitting 101A matches the position 703 of the center of the ultrasonic array sensor for receiving 101B (including the receiving array sensors 101B1 and 101B2). A configuration of an ultrasonic sensor 101P according to a first comparative example will now be described with reference to FIGS. 5A and 5B. FIG. 5A is a perspective view of the ultrasonic sensor 101P according to the first comparative example. FIG. 5B is a side view of the ultrasonic sensor 101P according to the first comparative example. As illustrated in FIG. 5A, the ultrasonic sensor 101P for transmission and reception has a transmitting sensor 801 and a receiving sensor 802 that are arranged side by side in the vertical direction (Y axis direction). As illustrated in FIG. 5B, the transmitting sensor 801 is located to be slightly rotated around the X axis with respect to the receiving array sensor 802. An acoustic field formed by an element 801A of the transmitting sensor 801 and an acoustic field formed by a group 802A of elements of the receiving array sensor 802 intersect with each other in an acoustic field intersection region 901 as illustrated in FIG. 5B. The intersected region can be imaged. As illustrated in FIG. 5A, if the positions of the centers of the transmitting and receiving sensors 801 and 802 are shifted from each other, a range in which a wave can be imaged is limited to the intersection region 901 in the Z axis direction, and the shift prevents a wave from being imaged in a large range. Operations of the ultrasonic observation equipment 10 according to the first embodiment of the invention are described with reference to FIG. 6, which is a diagram describing an example of parts included in the constituent elements of the ultrasonic observation equipment 10 according to the first embodiment of the invention and involved in transmission and reception of an ultrasonic wave. FIG. 6 is the schematic diagram illustrating that the single element ultrasonic sensor for transmitting 101A and the ultrasonic array sensor for receiving 101B are separated in order to describe the example. The single element ultrasonic sensor for transmitting 101A and the ultrasonic array sensor for receiving 101B, however, are actually integrated with each other as illustrated in FIG. 4. When an instruction to control ultrasonic transmission is provided through the user interface 104 of the external display unit 104 in accordance with an operation of the user, the communication unit 104C transmits a control signal through the processing unit 103 to the ultrasonic transceiver 102. The control signal that serves as a trigger signal 1401 (or a transmission trigger) is input to a high-voltage generator 1402 included in the pulsar 102A of the small ultrasonic transceiver 102. The high-voltage generator 1402 is synchronized with the trigger signal and generates a high-voltage pulse 1403. The high-voltage pulse 1403 is transmitted to the single element ultrasonic sensor for transmitting 101A. The single element ultrasonic sensor for transmitting 101A is displaced and generates an ultrasonic wave on the basis of the high-voltage pulse 1403 transmitted from the pulsar 102A. The single element ultrasonic sensor for transmitting 101A transmits the ultrasonic wave that spreads toward an object to be observed. The ultrasonic array sensor for receiving 101B converts displacements caused due to an ultrasonic wave reflected on the object to be observed into electric signals 1404. Specifically, the transducer elements (channels) that form the ultrasonic array sensor for receiving 101B generate the electric signals 1404 on the basis of the respective displacements. As a result, one electric signal 1404 corresponds to one channel. The amplification and conversion unit 102D that supports the multiple channels converts the received signals (electric signals) of each channel into digital signals per channel. The amplification and conversion unit 102D arranges the digital signals for the channels in a serial order or in the order of the arrangement of the channels and transmits the digital signals as a serial digital signal 1406 to the processing unit 103. Operations of the ultrasonic observation equipment 10 according to the first embodiment of the invention will now be described with reference to FIG. 7. FIG. 7 is a flowchart of the operations of the ultrasonic observation equipment 10 according to the first embodiment of the invention. The flowchart is mainly constituted of a process of transmitting an ultrasonic wave, a process of receiving an ultrasonic wave, and a process of imaging the ultrasonic wave received. When an instruction to control the ultrasonic transmission is provided through the user interface 104B of the external display unit 104 in accordance with an operation of the user, the communication unit 104C transmits a control signal through the processing unit 103 to the ultrasonic transceiver 102. The control signal that serves as the trigger signal 1401 (or the transmission trigger) is input to the high-voltage generator 1402 included in the pulsar 102A of the ultrasonic transceiver 102. The single element ultrasonic sensor for transmitting 101A is synchronized with the trigger signal and transmits an ultrasonic wave that spreads toward the object to be observed (in step S1501). The ultrasonic array sensor for receiving 101B converts a wave reflected from the object to be observed into electric signals and transmits the electric signals to the receiver 102B. The receiver 102B receives, from the ultrasonic array sensor for receiving 101B, the electric signals of the wave reflected from the object to be observed (in step S1502). The receiver 102B supplies the analog electric signals received from the ultrasonic array sensor for receiving 101B and converted from the reflected wave to the amplification and conversion unit 102D. The amplification and conversion unit 102D amplifies and converts the received analog electric signals into digital signals per transducer element (channel) included in the ultrasonic array sensor for receiving 101B (in step S1503). The amplification and conversion unit 102D arranges the digital signals for each channel in a serial order and transmits the digital signals as a serial digital signal 1406 to the processing unit 103 (in step S1504). A group S1514 of steps S1501 to S1504 is mainly executed at the ultrasonic transceiver 102. The communication unit 103C of the processing unit 103 (image processing unit) receives the serial digital signal 1406 from the amplification and conversion unit 102D (in step S1505). The image generator 103A divides the received serial digital signal into signals for each of the channels (in step S1506). The image generator 103A converts, for a J-th channel (J-th transducer element of the receiving array sensor), the L-th data order (L) of the received signal is converted into a reception time period LΔt corresponding to a round-trip propagation time on the basis of an acoustic velocity V of a medium located near the object to be observed and a sampling interval (Δt) (in step S1507). Thus, a digital data point sequence has strength of I (L) and can be regarded as a digital data point sequence having strength I (LΔt) for the reception time period LΔt due to the conversion. An ultrasonic image is formed as a map of digital data with pixel values of pixels two-dimensionally arranged in general. It is assumed that the number of all the pixels is M×N and a value of a pixel located at two dimensional coordinates (m, m) within the ultrasonic image is represented by p(m, n). For example, in order to generate a certain image, it is necessary to sequentially determine a pixel value for each of the number M×N of the pixels. A method for sequentially calculating the pixel values p(m, n) is described below while m is in a range of 1 to M, and n is in a range of 1 to N. The image generator 103A calculates, for the position (m, n) of a certain pixel, a sum r (m, n; L) of a distance between the center of the transmitting sensor and the pixel (m, n) and a distance between the pixel (m, n) and a receiving element (channel) with respect to data of the L-th channel (in step S1508). The image generator 103A calculates a pixel value p(m, n) of the pixel (m, n) by use of interpolating strength I(KΔt) and I[(K+1)Δt], calculated according to Inequality (1), of K-th digital data into the following Equation (2) (in step S1509). The interpolation is not limited to linear correlation of Equation (2) and may be correlation with the use of a polynomial.Inequality (1)VKΔt≦r(m,n)<V(K+1)Δt (1)Equation (2)p(m,n)=b/(a+b)I[(K)Δt]+a/(a+b)I[(K+1)Δt] (2), where a=r(m, n)−VKΔt, b=V(K+1)Δt−r(m, n), and a+b=VΔt. The image generator 103A repeatedly calculates the positions (m, n) of the pixels and thereby generates a map of values of the number M×N of all the pixels so as to generate an image. The image is for the L-th channel. The image generator 103A causes the image to be stored in the storage unit (in step S1510). Whichever pixel positions the calculation of a pixel value is started from, the calculation of the pixel value of the pixel position (m, n) will not affect pixel values of the other pixel positions in principle. Since an algorithm that enables arithmetic elements of the image generator 103A to easily calculate pixel values in parallel is used, speeding up the imaging processing can be achieved. The image generator 103A can generate images for all the channels included in the ultrasonic array sensor through repeating the process that is executed on the L-th channel. The image generator 103A sums images for the pixel positions (m, n) according to the following Equation (3) and thereby calculates pixel values p(m, n) of a received image. In Equation (3), Σ_L represents an addition of the values to the channel L.p(m,n)=Σ_Lp(m,n;L) (3) Image computation related to a reception channel can be executed independently from image computation related to another channel. Accordingly, image construction of each channel can be easily calculated in parallel, whereby the speeding-up of image processing is achieved. The image generator 103A causes image data obtained as a result of summing the images according to Equation (3) to be stored in the storage unit 103B (in step S1511). An image obtained as a result of summing images from all the channels is an ultrasonic image of the received signal. The image generator 103A transmits the ultrasonic image formed in response to the transmission trigger used in S1501 to the external display unit 104 (in step S1512). The external display unit 104 displays data of the ultrasonic image transmitted from the processing unit 103 on the display unit 104A (in step S1513). If a certain repetition frequency is set up after the display of the ultrasonic image, the image generator 103A generates a transmission trigger for ultrasonic transmission and transmits the transmission trigger to the small ultrasonic receiver 102. As a result, a command to transmit an ultrasonic wave is transmitted to the small ultrasonic receiver 102. A group of steps S1505 to S1512 is executed at the processing unit 103. As described above, in the present embodiment, the small ultrasonic receiver 102 performs neither a complex delay control nor a complex synthesis process. Instead, the small ultrasonic receiver 102 transmits the serial digital signal obtained as a result of conversion of the received wave to the processing unit 103, thereby making it possible to downsize the ultrasonic transceiver. Since it is not necessary to reduce the number of transducer elements, the quality of an ultrasonic image can be maintained. In addition, the single element ultrasonic sensor for transmitting 101A that includes the single transducer element transmits an ultrasonic wave, whereby a circuit for transmission can be simplified and the equipment can be downsized. Downsizing of the transceiver makes visualization of an object to be observed located at a cramped portion easier with the use of an ultrasonic wave. Further, the processing unit 103 processes a digital signal using the algorithm that enables the parallel process to be easily executed. Thus, the processing unit 103 that has high throughput can be placed far from the transceiver 102, as well as execute the image processing at a high speed. In this case, an ultrasonic image is transferred to the external display unit 104 through communication, whereby the user can confirm the image displayed rapidly. A configuration of the ultrasonic sensor 101 according to a first modified example will now be described with reference to FIG. 8. FIG. 8 is a diagram illustrating the configuration of the ultrasonic sensor 101 according to the first modified example. Since the ultrasonic sensor 101 does not need to contact an object to be observed in underwater inspection, a front surface of the ultrasonic sensor 101 may have curvature. The ultrasonic sensor 101 has protruding surface portions extending in the direction (X axis direction) parallel to the direction in which the transducer element groups (101B1 and 101B2) that form the ultrasonic array sensor for receiving 101B are arranged. The ultrasonic sensor 101 has a concaved surface in the longitudinal direction (Y axis direction) of elements of the transducer element groups (101B1 and 101B2) that form the ultrasonic array sensor for receiving 101B, while the longitudinal direction (Y axis direction) is perpendicular to the normal direction (Z axis direction) of the elements and the X axis direction. In the example illustrated in FIG. 8, the single element ultrasonic sensor for transmitting 101A and the ultrasonic array sensor for receiving 101B (101B1 and 101B2) are arranged on the saddle type surface TS. Accordingly, an acoustic field 1302A of an ultrasonic wave transmitted by the single element ultrasonic sensor for transmitting 101A is focused in the Y axis direction and spreads in the X axis direction. An acoustic field 1303C of an ultrasonic wave to be received can be focused in the longitudinal direction (Y axis direction) of the transducer elements, whereas an effect of the focusing in the Y axis direction is not obtained in the image processing. Therefore, a range in which the acoustic field of the ultrasonic wave transmitted intersects with the acoustic field of the ultrasonic wave to be received can be efficiently formed, and an SN ratio of an image can be improved. The protruding surface portions that extend in the X axis direction are formed for the acoustic field of the ultrasonic wave to be received, and the protruding surface normally makes the acoustic field of the ultrasonic wave to be received spread. However, since the ultrasonic sensor 101 has an array structure, the focusing effect can be obtained in the process of processing a signal in order to form an image, and an effect of spreading the acoustic field of the ultrasonic wave to be received can be offset. A configuration of the ultrasonic sensor 101 according to a second modified example will now be described with reference to FIG. 9. FIG. 9 is a diagram illustrating the configuration of the ultrasonic sensor 101 according to the second modified example. The ultrasonic sensor 101 having transmission and reception integrated in FIG. 9 has the single element ultrasonic sensor for transmitting 101A and the ultrasonic array sensor for receiving 101B that intersect with each other in a cross shape (or extend in the directions perpendicular to each other). An acoustic field 1101A of an ultrasonic wave to be received by the ultrasonic array sensor for receiving 101B widely spreads in the X axis direction. An acoustic field 1102A of the single element ultrasonic sensor for transmitting 101A spreads in the X axis direction, and a region that can be imaged is represented by reference numeral 1103. A configuration of the ultrasonic sensor 101 according to a third modified example will now be described with reference to FIG. 10. FIG. 10 is a diagram illustrating the configuration of the ultrasonic sensor 101 according to the third modified example. Although the ultrasonic sensor 101 that has the configuration illustrated in FIG. 9 still can image an object to be observed, a region that is included in a region of the acoustic field 1102A of the ultrasonic wave transmitted and used for the formation of the intersecting region 1103 is narrow, which may lead to fear for a low efficiency and a low SN ratio. As an example of improving the aforementioned case, transducer elements of the ultrasonic sensor 101 are arranged not only in X axis direction but also in Y axis direction as illustrated in FIG. 10, for example. The ultrasonic sensor 101 illustrated in FIG. 10 is configured by the expanded (or transformed) ultrasonic sensor 101 illustrated in FIG. 4. Groups 101B3 and 101B4 of transducer elements of the ultrasonic sensor 101 are arranged in the Y axis direction or the vertical direction as a part of the ultrasonic array sensor for receiving 101B. Even when an acoustic field 1201 formed by the single element ultrasonic sensor for transmitting 101A is wide, an acoustic field of an ultrasonic wave to be received by the ultrasonic array sensor for receiving 101B in an XY plane can be increased, and a range that enables the ultrasonic imaging to be executed can be expanded. A configuration of an ultrasonic sensor 101Q according to a second comparative example will now be described with reference to FIG. 11. FIG. 11 is a diagram illustrating the configuration of the ultrasonic sensor 101Q according to the second comparative example. A receiving array sensor 1001 forms an acoustic field 1001A of an ultrasonic wave to be received. A transmitting array sensor 1002 forms an acoustic field 1002A of an ultrasonic wave transmitted. Since the transmitting and receiving array sensors 1002 and 1001 each have an array of elements, the ultrasonic sensor 101Q needs to transmit an ultrasonic wave in accordance with delay control of a phased array system or execute electronic scanning in a direction in which an ultrasonic wave is received. Thus, a transceiver cannot be downsized. In addition, a region 1003 in which the acoustic field 1002A intersects with the acoustic field 1001A is small. A configuration of the ultrasonic observation system 100 that includes the ultrasonic observation equipment 10 according to a second embodiment of the invention will now be described with reference to FIG. 12. FIG. 12 is a diagram illustrating the configuration of the ultrasonic observation system 100 that includes the ultrasonic observation equipment 10 according to the second embodiment of the invention. Hereinafter, a case in which a plant is inspected will now be described as an example. A cramped portion in which objects 1602 to be inspected that are tubes and the like are arranged close to each other is included in a building 1601. The cramped portion may lower an operability of an operator 1603. According to the second embodiment, the operability can be improved by use of the small ultrasonic observation equipment as described below. As illustrated in FIG. 12, the operator 1603 carries the small ultrasonic transceiver 102 and the ultrasonic sensor 101 which is in contact with an object 1602 to be inspected such as a tube. The communication unit 102E of the small ultrasonic transceiver 102 communicates with a communication relay device 1601A of the plant building 1601 that includes the object to be inspected. The communication relay device 1601A is connected to a communication network N through a cable (communication cable) 1601B, but may be wirelessly connected to the communication network N. The communication relay device 1601A is wirelessly connected to the communication unit 102E, but may be connected to the communication unit 102E through the cable 1601B. The devices connected to the communication relay device 1601A belong to a single communication network. The small ultrasonic transceiver 102 is connected through the relay device 1601A to the processing unit 103 installed in an external office 1604 by way of communication. The processing unit 103 uses the communication unit 103C to communicate with a communication relay device 1604A installed in the external office 1604. The communication relay device 1604A is connected to the communication network N through a cable 1604B, but may be wirelessly connected to the communication network N. In addition, the relay device 1604A is wirelessly connected to the communication unit 103C, but may be connected to the communication unit 103C through the cable 1604B. The devices connected to the communication relay device 1604A belong to another single communication network. The processing unit 103 generates an ultrasonic image on the basis of signals of a received wave transmitted from the small ultrasonic transceiver 102. The processing unit 103 uses the communication unit 103C to transmit the generated ultrasonic image through the relay device 1604A of the external office 1604, the communication network N, and the relay device 1601A installed in the plant building 1601 to the communication unit 104C of the external display unit 104. The external display unit 104 displays the ultrasonic image and the user interface 104B on the display unit 104A. The user interface 104B is used for the operator 1603 to control the ultrasonic observation equipment. The operator 1603 who performs a task of observing the cramped portion included in the plant only needs to take the small ultrasonic transceiver 102 with himself/herself. Since the external display unit 104 is wirelessly connected to the relay device 1601A, the external display unit 104 can be placed at any location as long as the external display unit 104 is connected to the relay device 1601A and does not lower the operability. As described above, according to the present embodiment, an object to be observed located at a cramped portion can be easily visualized with the use of an ultrasonic wave while the quality of an ultrasonic image is maintained. In addition, a cramped portion can be observed in air by the operator while an image can be displayed at a high speed. An example of the effects of the first and second embodiments will now be described below. The small ultrasonic transceiver 102 converts received signals into digital signals and transmits the digital signals to a processing system installed in the external office without performing complex delay control, unlike conventional techniques. After the digital signals are subjected to image processing by the processing system, the image data is transmitted again and displayed by the external display unit 104 installed in an external device. In this manner, the transceiver handles only raw data of digital signals without executing delay synthesis and additive synthesis on a received wave. Thus, the equipment can be downsized, and transportation into a cramped portion and observation of the cramped portion can be achieved. A signal having its received wave going through analog-to-digital conversion (A/D conversion) is subjected to image synthesis by the processing system (processing unit 103) installed in the external office. The processing system is connected to the small transceiver 102 through communication. Thus, the processing system may have a large-capacity memory and a high-accuracy arithmetic element, each of which may be required for high-speed image synthesis. In addition, the processing system is configured as an external device. Even if the volume of the processing system is large, the processing system will not affect the volume of the small ultrasonic transceiver and the volume of the ultrasonic sensor, each of which may be placed near an object to be observed, and the processing system will not reduce operability at the cramped portion. Ultrasonic image data is displayed on the external display unit 104. The external display unit 104 is a system configured as an external device. Thus, even if the display unit 104A is a monitor with a large display area or the like, the external display unit 104 will not reduce the operability at the cramped portion. The invention is not limited to the aforementioned embodiments and includes various modified examples. For example, the embodiments are described in detail in order to clearly describe the invention and are not limited to the system and the equipment that have the configurations described above. A part of a configuration described in the first or second embodiment may be replaced with a part of a configuration described in the other embodiment. A part of a configuration described in the first or second embodiment may be added to a configuration described in the other embodiment. A part of the configurations described in the first and second embodiments may be deleted. For example, in the second embodiment, the communication network to which the devices connected to the communication relay device 1601A belong is directly connected to the communication network to which the devices connected to the communication relay device 1604A belong without the communication network N.
	summary
052606210	summary	FIELD OF THE INVENTION The present invention relates to radio-nuclide, voltaic-junction batteries, and, more particularly, to compact electric batteries that are powered by the combination of a nuclear radiation emitting source and a responsive semiconductor voltaic junction for service in many applications where chemical batteries are unsatisfactory or inferior. THE PRIOR ART Compact long-life energy sources have wide applications in such fields as aerospace systems, cardiac pacemakers, computer memory maintenance, remote instrumentation, etc. Chemical batteries suffer generally from theoretical limits in the energy density, they can accommodate. Radio-nuclide, voltaic-junction cells have much higher theoretical limits in energy density, in some cases more than a factor of 1000 greater, but, in the past, have not achieved desirable high energy density and long life in practice. A major problem in such prior art cells has been the limited ability of semiconductor junctions to withstand high energy alpha or beta emission without damage during operation. Silicon p-n junction cells for directly converting radiation, either visible or ionizing, to electricity were developed in the early 1950's. Specific use of radio-isotopes to power silicon p-n cells, known as betavoltaic cells, were extensively studied in the 1970's for applications where low power but high energy density were important, for example, in cardiac pacemakers. A primary motivation for these studies was that the theoretical energy density is much higher in betavoltaic cells than in the best chemical batteries, 24.3 W-h/cm.sup.3 versus 0.55 W-h/cm.sup.3 for mercury-zinc batteries. Unfortunately, isotopes that could be employed with silicon had to be limited to low energy beta emitters because of radiation damage. For example, threshold energy for electron damage is about 0.180 MeV assuming an atomic displacement damage threshold of 12.9 eV. Alpha particles cause so much damage that they were not seriously considered at any energy. This constraint excluded the most potent nuclide sources, and thus restricted maximum power of such devices because of limits to the specific activity achievable at maximum concentration with reasonable half-lives. BRIEF DESCRIPTION OF THE INVENTION The primary object of the present invention is to provide a novel high energy density electric cell comprising a nuclear source of relatively high energy radiation and concomitant heat, a semiconductor junction incorporating an inorganic crystalline compound of Group III and Group V elements characterized by defect generation in response to the nuclear source, and an enclosure having a sufficiently high thermal impedance to retain therewithin a sufficient quantity of the heat generated by the nuclear source for maintenance of the semiconductor junction above a predeterminedly high annealing temperature during operation. The nuclear radiation includes energetic radiation such as alpha, beta and gamma emissions or combinations thereof. The semiconductor junction, for example, includes compounds of indium and phosphorous differentially treated with n or p dopants. The thermal impedance is composed of a thermal insulator such as a ceramic electrical non-conductor. The arrangement is such that damage to the semiconductor junction resulting from the highly energetic emissions from the nuclear source is repaired by annealing in real time at the predetermined temperature maintained within the insulating enclosure. Other objects of the present invention will in part be obvious and will in part appear hereinafter.
048287601	claims	1. A method of cleaning a fuel assembly including surfaces thereof prior to decladding, each assembly surface contaminated with a radioactive alkali metal and comprising a plurality of pressurized metallic fuel pins containing a spent fissible material, the method comprising the sequential steps of: (a) placing the fuel assembly in a sealed chamber; (b) passing a heated, inert gas through the chamber to heat the fuel assembly to a temperature sufficient to cause volatilization of the alkali metal but insufficient to rupture the pressurized metal pins; (c) evacuating the chamber to a pressure of less than 0.5 mm of Hg to further enhance volatilization and removal of the alkali metal and maintaining the chamber at that pressure until the decay heat of the fissile materials causes the temperature of the fuel assembly to increase to a level which would be detrimental to the integrity of the metal pins; (d) cooling the fuel assembly by passing a cool, inert gas through the chamber to reduce the temperature of the fuel assembly to a desired level; (e) repeating the evacuation and cooling steps as required to insure removal of substantially all of the radioactive alkali metal from the assembly surface; and (f) recovering the cleaned fuel assembly from the chamber. (a) placing the fuel assembly in a sealed chamber, (b) passing a heated inert argon gas through the chamber to heat the fuel assembly to a temperature of about 800.degree. F., (c) evacuating the chamber to a pressure of less than about 0.05 mm of mercury and maintaining the fuel assembly and chamber at that pressure until the temperature of the fuel assembly is about 1000.degree. F., (d) passing a cool inert argon gas through the chamber and the fuel assembles to reduce the temperature of the fuel assembly to about 800.degree. F., (e) repeating steps c and d as required to ensure removal of substantially all of the radioactive alkali metal, and (f) recovering the decontaminated fuel assembly from the chamber. (a) placing the fuel assembly in a sealed chamber; (b) passing a heated inert argon gas through the chamber to heat the fuel assembly to a temperature of about 800.degree. F.; (c) evacuating the chamber to a pressure of less than about 0.05 mm of mercury and maintaining the fuel assembly and chamber at that pressure until the temperature of the fuel assembly is about 1000.degree. F.; (d) passing a cool inert argon gas through the chamber and the interior of the fuel assembly to reduce the temperature of the fuel assembly to about 800.degree. F.; (e) repeating steps c) and d) as required to insure removal of substantially all of the radioactive alkali metal from the assembly surface; and (f) recovering the cleaned fuel assembly from the chamber. 2. A method of claim 1 wherein said alkali metal is sodium. 3. A method of claim 1 wherein said alkali metal is a mixture of sodium and potassium. 4. The method of claim 1 wherein in step c) the chamber is evacuated to a pressure of less than about 0.005 mm of mercury. 5. The method of claim 1 wherein the fuel assembly free of contaminants is processed for the recovery of fissile material therefrom. 6. The method of claim 1 in which gas exiting the sealed chamber from steps c) and d) is passed in indirect heat exchange relationship with a coolant for the condensation and removal of any vaporized alkali metal therefrom. 7. The method of claim 6 wherein the gas from step c) is further conducted through a cryogenic trap to insure substantially complete removal of any remaining radioactive alkali metal from the gas. 8. A method of decontaminating a fuel assembly contaminated with a radioactive alkali metal, each fuel assembly comprising a plurality of metal pins containing a spent fissile material selected from a group consisting of carbides and oxides the method comprises the sequential steps of: 9. A method of cleaning a fuel assembly including surfaces thereof prior to decladding, each assembly surface contaminated with a radioactive alkali metal and comprising a plurality of pressurized metallic fuel pins containing a spent fissible material selected from the group consisting of carbides and oxides, the method comprising the sequential steps of: 10. The method of claim 9 in which gas exiting from the sealed chamber in steps c) and d) is passed in indirect heat exchange relatipnship with a coolant for the condensation and removal of vaporized alkali metal therefrom. 11. The method of claim 10 wherein the gas from step c) is further conducted through a cryogenic trap to insure substantially complete removal of any remaining radioactive alkali metal from the gas. 12. The method of claim 11 wherein said alkali metal is sodium. 13. The method of claim 11 wherein said alkali metal is a mixture of sodium and potassium. 14. The method of claim 11 wherein in step c) the chamber is evacuated to a pressure of less than 0.005 mm of mercury. 15. The method of claim 14 wherein the fuel assembly which is free of contaminants is processed for the recovery of fissile material therefrom.
	claims	1. A specimen fabricating apparatus comprising:a specimen stage, on which a specimen is placed;a charged particle beam optical system to irradiate a charged particle beam on the specimen;an etchant material supplying source to supply an etchant material, which contains fluorine and carbon in molecules thereof, does not contain oxygen in molecules thereof, and is solid or liquid in a standard state; anda vacuum chamber to house therein the specimen stage. 2. The specimen fabricating apparatus according to 1, wherein the etchant material is F(CF2)12F. 3. The specimen fabricating apparatus according to 1, wherein the etchant material is (CF2)15F3N. 4. The specimen fabricating apparatus according to 1, wherein the etchant material is I(CF2)8I. 5. The specimen fabricating apparatus according to 1, wherein the etchant material supplying source has a cartridge type construction which enables exchange of the etchant material. 6. The specimen fabricating apparatus according to 5, further comprising a cartridge holder to fix the cartridge, and wherein the cartridge holder comprises means to heat the cartridge. 7. A specimen fabricating apparatus comprising:a movable specimen stage, on which a specimen is placed;a charged particle beam optical system to irradiate a charged particle beam on the specimen;an etchant material supplying source to supply an etchant material, in molecules of which a ratio of fluorine to carbon in number is 2 or more and which is solid or liquid in a standard state, to the specimen; anda vacuum chamber to house therein the specimen stage. 8. The specimen fabricating apparatus according to 7, wherein the etchant material is F(CF2)12F. 9. The specimen fabricating apparatus according to 7, wherein the etchant material is (CF2)15F3N. 10. The specimen fabricating apparatus according to 7, wherein the etchant material is I(CF2)8I. 11. The specimen fabricating apparatus according to 7, wherein the etchant material supplying source has a cartridge type construction which enables exchange of the etchant material. 12. The specimen fabricating apparatus according to 11, further comprising a cartridge holder to fix the cartridge, and wherein the cartridge holder comprises means to heat the cartridge. 13. A specimen fabricating method comprising the steps of:processing a hole in the vicinity of a requested region of a specimen by means of irradiation of a charged particle beam;exposing the requested region by means of irradiation of the charged particle beam;supplying an etchant material, which contains fluorine and carbon in molecules thereof, does not contain oxygen in molecules thereof, and is solid or liquid in a standard state, to the requested region as exposed; andirradiating the charged particle beam on the requested region as exposed. 14. The specimen fabricating method according to 13, wherein the etchant material is composed of molecules, of which a ratio of fluorine to carbon in number is 2 or more, and is solid or liquid in a standard state. 15. The specimen fabricating method according to 14, wherein the etchant material is F(CF2)12F. 16. The specimen fabricating method according to 14, wherein the etchant material is (CF2)15F3N. 17. The specimen fabricating method according to 14, wherein the etchant material is I(CF2)8I. 18. The specimen fabricating method according to 13, wherein the etchant material is F(CF2)12F. 19. The specimen fabricating method according to 13, wherein the etchant material is (CF2)15F3N. 20. The specimen fabricating method according to 13, wherein the etchant material is I(CF2)8I. 21. A portable charging vessel used for a focused ion beam apparatus provided with an etch-assisting gas supplying source for supplying of an etch-assisting gas into a vacuum chamber, and storing therein the etch-assisting gas,wherein the portable charging vessel comprises an opening, through which a gas is supplied to a pipe, a joint surface vacuum-sealed to the etch-assisting gas supplying source, and a seal member to hermetically seal the opening, andwherein the etchant material contains fluorine and carbon in molecules thereof, does not contain oxygen in molecules thereof, and is solid or liquid in a standard state. 22. The portable charging vessel according to 21, wherein the etchant material is F(CF2)12F, (CF2)15F3N, or I(CF2)8I.
041742931	abstract	A process for disposing of radioactive aqueous waste solutions whereby the waste solution is utilized as the water of hydration to hydrate densified powdered portland cement in a leakproof container; said waste solution being dispersed without mechanical inter-mixing in situ in said bulk cement, thereafter the hydrated cement body is impregnated with a mixture of a monomer and polymerization catalyst to form polymer throughout the cement body. The entire process being carried out while maintaining the temperature of the components during the process at a temperature below 99.degree. C. The container containing the solid polymer-impregnated body is thereafter stored at a radioactive waste storage dump such as an underground storage dump.
	claims	1. A buckstay system for a wall of a steam generator having a first wall section which meets a second wall section at an angle to form a corner, the system comprising:a plurality of horizontal buckstay assemblies each comprisinga horizontal buckstay extending generally horizontally across each wall section such as to form a connected pair with an adjacent horizontal buckstay at the said corner,an elongate tie bar formation extending across each wall section such as to form a fixedly mounted pair with an adjacent tie bar formation at the said corner, andan anchor assembly associated with each horizontal buckstay and providing engagement means by which each horizontal buckstay engages with a respective tie bar; and the system further comprisinga plurality of vertical buckstays connected to support and space said horizontal buckstay assemblies vertically up the steam generator; whereineach said horizontal buckstay is split to comprise at least two rigid elongate horizontal buckstay elements mounted together to be relatively slidable in a buckstay longitudinal direction;vertical buckstays are provided in the vicinity of some or all of the points where horizontal buckstay elements of a horizontal buckstay are slidingly engaged; andat a sliding engagement point between two horizontal buckstay elements a vertical support is provided having a fixed engagement with one said horizontal buckstay element, and having a sliding engagement with the other said horizontal buckstay element whereby the other said horizontal buckstay element may slide horizontally relative to the vertical support and relative to the one said horizontal buckstay element. 2. A buckstay system in accordance with claim 1 wherein the connected pair of horizontal buckstays is connected at the said corner by a mechanical connection that does not provide for any expansion in a longitudinal direction. 3. A buckstay system in accordance with claim 1 wherein the connected pair of horizontal buckstays is connected at the said corner by fixed mechanical engagement between a bracket portion on an end of a first such buckstay and a receiving portion on an end of a second such buckstay. 4. A buckstay system in accordance with claim 1 wherein each anchor assembly comprises a support formation fixedly engaged with a horizontal buckstay element, and a bearing surface located to bear upon and engage in use with a surface of a tie bar. 5. A buckstay system in accordance with claim 4 wherein the support formation is a support plate. 6. A buckstay system in accordance with claim 5 wherein two rectangular support plates, comprising an upper and a lower support plate, are deployed above and below a horizontal buckstay element. 7. A buckstay system in accordance with claim 6 wherein the support plates comprise additional stiffening plates in a direction parallel to and/or perpendicular to a longitudinal direction of the horizontal buckstay. 8. A buckstay system in accordance with claim 1 wherein each anchor assembly is provided on a horizontal buckstay element no more than 600 mm inboard of a corner formed by its associated wall and the adjacent wall. 9. A buckstay system in accordance with claim 1 wherein the adjacent tie bars are fixedly mounted to each other at the corner by means of an end connection corner angle reinforcement tie welded to the pair of tie bars. 10. A buckstay system in accordance with claim 1 wherein each horizontal buckstay element comprises a rigid elongate structural member having a web shaped surface. 11. A buckstay system in accordance with claim 10 wherein a sliding engagement connection is provided between a pair of horizontal buckstay elements which permits sliding movement in a longitudinal direction of the two horizontal buckstay elements by means of relative sliding of the web surfaces. 12. A buckstay system for a wall of a steam generator having plural wall sections which meet adjacent wall sections at an angle comprising:a plurality of horizontal buckstay assemblies each comprisinga horizontal buckstay extending generally horizontally across each wall section such as to form a connected pair with an adjacent horizontal buckstay at each said corner,an elongate tie bar formation extending across each wall section such as to form a fixedly mounted pair with an adjacent tie bar formation at each said corner, andan anchor assembly associated with each horizontal buckstay and providing engagement means by which each horizontal buckstay engages with a respective tie bar; and the system further comprisinga plurality of vertical buckstays connected to support and space said horizontal buckstay assemblies vertically up the steam generator; whereineach said horizontal buckstay is split to comprise at least two rigid elongate horizontal buckstay elements mounted together to be relatively slidable in a buckstay longitudinal direction;vertical buckstays are provided in the vicinity of some or all of the points where horizontal buckstay elements of a horizontal buckstay are slidingly engaged; andat a sliding engagement point between two horizontal buckstay elements a vertical support is provided having a fixed engagement with one said horizontal buckstay element, and having a sliding engagement with the other said horizontal buckstay element whereby the other said horizontal buckstay element may slide horizontally relative to the vertical support and relative to the one said horizontal buckstay element. 13. A buckstay system in accordance with claim 12 wherein each anchor assembly comprises a support formation fixedly engaged with a horizontal buckstay element, and a bearing surface located to bear upon and engage in use with a surface of a tie bar. 14. A buckstay system in accordance with claim 13 wherein the support formation is a support plate. 15. A buckstay system in accordance with claim 14 wherein two rectangular support plates, comprising an upper and a lower support plate, are deployed above and below a horizontal buckstay element. 16. A buckstay system in accordance with claim 15 wherein the support plates comprise additional stiffening plates in a direction parallel to and/or perpendicular to a longitudinal direction of the horizontal buckstay. 17. A buckstay system in accordance with claim 12 wherein each anchor assembly is provided on a horizontal buckstay element no more than 2 m inboard of a corner formed by its associated wall and the adjacent wall. 18. A buckstay system in accordance with claim 17 wherein each anchor assembly is within 600 mm of such a corner. 19. A buckstay system in accordance with claim 12 wherein the adjacent tie bars are fixedly mounted to each other at the corner by means of an end connection corner angle reinforcement tie welded to the pair of tie bars. 20. A buckstay system in accordance with claim 12 wherein each horizontal buckstay element comprises a rigid elongate structural member having a web shaped surface. 21. A buckstay system in accordance with claim 20 wherein a sliding engagement connection is provided between a pair of horizontal buckstay elements which permits sliding movement in a longitudinal direction of the two horizontal buckstay elements by means of relative sliding of the web surfaces.
	summary
	summary
	claims	1. A method for determining tracking control parameters for positioning an x-ray beam of a computed tomography imaging system, the imaging system including a movable collimator positionable in steps and a detector array including a plurality of rows of detector elements, said method comprising: obtaining detector samples at a plurality of collimator step positions while determining a position of a focal spot of the x-ray beam; determining a beam position for each detector element at each collimator step utilizing the determined focal spot positions, a nominal focal spot length, and geometric parameters of the x-ray beam, collimator, and detector array; and determining a detector element differential error according to ratios of successive collimator step positions. 2. A method in accordance with claim 1 wherein the plurality of detector rows are z-axis detector rows, and the detector array has a centerline perpendicular to the z-axis, an outer detector row, and an inner detector row; said method further comprising determining a collimator z-axis position offset from the detector array centerline at a point at which outer detector row signals are reduced to a full width at a half maximum. claim 1 3. A method in accordance with claim 1 further comprising offset-correcting and view-averaging the obtained detector samples at a plurality of collimator step positions to obtain a set of detector samples for each collimator step position used in determining a beam position transfer function and determining a differential error for selection of the target beam position. claim 1 4. A computed tomography imaging system comprising an x-ray source, a detector array including a plurality of rows of detector elements, and a movable collimator positionable in steps and configured to collimate and position an x-ray beam produced by said x-ray source on said detector array, said system configured to: obtain detector samples at a plurality of collimator step positions while determining a position of a focal spot of the x-ray beam; determine a beam position for each detector element at each collimator step utilizing the determined focal spot positions, a nominal focal spot length, and geometric parameters of the x-ray beam, collimator, and detector array; and determine a detector element differential error according to ratios of successive collimator step positions. 5. A system in accordance with claim 4 wherein the plurality of detector rows are z-axis detector rows, and the detector array has a centerline perpendicular to the z-axis, an outer detector row, and an inner detector row; and said system further configured to determine a collimator z-axis position offset from the detector array centerline at a point at which outer detector row signals are reduced to a full width at a half maximum. claim 4 6. A system in accordance with claim 4 further configured to offset-correct and view-average the obtained detector samples at a plurality of collimator step positions to obtain a set of detector samples for each collimator step position used in determining a target beam position transfer function and in determining said differential-error for selection of said target beam position. claim 4

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