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	abstract	A radiation monitor includes an AC control section and a DC control section. The AC control section outputs an AC power source instantaneous power failure detection signal to the DC control section when a decrease in AC voltage is detected. The DC control section measures a duration time of an AC power source instantaneous power failure detection signal when the AC power source instantaneous power failure detection signal is received from the AC control section and outputs an instantaneous power failure restart signal to the AC control section if the AC voltage is restored within a time shorter than a set value. The AC control section performs switching control from close to open of the sampling solenoid valve, the purge solenoid valve, and the exhaust solenoid valve, and restarts the pump after a constant time when the instantaneous power failure restart signal is received from the DC control section.
	description	The disclosure relates to the technical field of medical devices, in particular to an adjustable collimator, a collimation system, a therapy head and a radiotherapy device. Existing radiotherapy devices usually adopt multi-source focusing to carry out radiotherapy on diseased parts, but due to the differences of the positions, sizes and therapy precision requirements of different diseased parts, different specifications of collimators need to be changed frequently for adjusting the diameter size and shape of a ray beam, and focusing target spots with different focusing sizes are formed so as to meet the shape, size and ray dosage required when a ray passes through the focusing target spots. However, due to the structural constraint of existing radiotherapy devices and collimators, the types of the existing collimators are few, the beam formed by the ray is single in shape and relatively large in irradiation field, but the precision requirement of small irradiation field therapy cannot be reached to cause that the precision of radiotherapy is relatively low to influence the therapy effect. In view of this, the present invention provides an adjustable collimator, a collimation system, a therapy head and a radiotherapy device, and solves the technical problem that existing collimators cannot achieve precise therapy in a small irradiation field so as to influence the therapeutic effect. According to an embodiment of the present invention, the provided adjustable collimator comprises a controller and two blade sets arranged opposite to each other, the blade sets comprise a plurality of blades, the controller drives the blades to move so as to form a first irradiation field through which a ray can pass, at least one blade in the blade set is a small irradiation field blade, at least one irradiation field hole is provided on the small irradiation field blade, and the controller is further used to drive the small irradiation field blade to move such that the irradiation field hole becomes a second irradiation field through which the ray can pass. For example, the small radiation field blade is provided at the central position of the blade set. For example, the irradiation field holes on the small irradiation field blade are provided on the small irradiation field blade in an equally-spaced manner. For example, the irradiation field holes on the small radiation field blade are different in hole diameters. For example, the irradiation field holes on the small irradiation field blade are provided on the small irradiation field blade in size order. For example, the irradiation field holes are provided from the center of the small irradiation field blade to two sides of the small irradiation field blade in size order sequentially. For example, the controller comprises a first control module for controlling and driving the blades to move along the plane of a cutting ray so as to form the first irradiation field when an expected irradiation field is larger than or equal to the minimum value of the first irradiation field and a second control module for controlling and driving a second irradiation field hole with expected size in the small irradiation field blade so as to form the second irradiation field when the expected irradiation field is smaller than the minimum value of the first irradiation field. For example, the widths of the small irradiation field blades are greater than those of other blades. According to another embodiment of the present invention, a collimation system is provided, and the collimation system comprises a radioactive source and the adjustable collimator. According to another embodiment of the present invention, a therapy head is provided, and the therapy head comprises at least two radioactive sources and any of the adjustable collimators provided in the embodiment of the present invention, and radioactive rays emitted by the radioactive sources are focused in the same area through the corresponding adjustable collimators. According to another embodiment of the present invention, a radiotherapy device is provided, and the radiotherapy device comprises the adjustable collimator, the collimation system or the therapy head. In the adjustable collimator, the collimation system, the therapy head and the radiotherapy device provided by the present invention, the adjustable collimator comprises a controller and two blade sets arranged opposite to each other, the blade sets comprise a plurality of blades, the controller drives the blades to move so as to form a first irradiation field through which a ray can pass, at least one blade in the blade set is a small irradiation field blade, at least one irradiation field hole is provided on the small irradiation field blade, and the controller is further used to drive the small irradiation field blade to move such that the irradiation field hole becomes a second irradiation field through which the ray can pass, so that the collimator provided in the embodiment of the present invention can quickly and flexibly form the first irradiation field or the second irradiation field according to the position, size and dosage requirements of an actual therapeutic ray so as to reach a conformal irradiation focus point with expected size and ray dosage, precise therapy on diseased parts is achieved, and the therapeutic effect of radiotherapy is improved. The technical solutions of the present invention are further described in detail in conjunction with the following drawings and embodiments. Apparently, the embodiments in the following description are merely a part rather than all of the embodiments of the present invention. Based on the embodiment in the present invention, all other embodiments obtained by the ordinary technical staff in the art under the premise of without contributing creative labor belong to the scope protected by the present invention. In the description of the present invention, it needs to be illustrated that the terms such as “first” and “second” are just used for description purpose, but cannot be understood to indicate or hint relative importance. In the description of the present invention, it further needs to be illustrated that, except as otherwise noted, the terms such as “link” and “connect” should be generally understood, for example, the components can be fixedly connected, and also can be detachably connected or integrally connected; the components can be mechanically connected, and also can be electrically connected; the components can be directly connected, also can be indirectly connected through an intermediate. For any person skilled in the art, the specific meanings of the terms in the present invention can be understood according to specific conditions. Moreover, in the description of the present invention, except as otherwise noted, the meaning of “a plurality of” indicates two or more than two. Any process, method or block in the flowchart or described in other manners herein may be understood as being indicative of including one or more modules, segments or parts for realizing the codes of executable instructions of the steps in specific logic functions or processes, and that the scope of the preferred embodiments of the present invention include other implementations, wherein the functions may be executed in manners different from those shown or discussed (e.g., according to the related functions in a substantially simultaneous manner or in a reverse order), which shall be understood by a person skilled in the art. FIG. 1 is a structure diagram of an adjustable collimator 100 in one embodiment of the present invention. As shown in FIG. 1, the adjustable collimator 100 comprises two blade sets 20 arranged opposite to each other, a plurality of lead screws 30, a plurality of drive motors 40 and a controller (not shown). The blade sets 20 comprise a plurality of blades. The blades are correspondingly connected with the lead screws 30 and are oppositely arranged inside the inner accommodating space of the adjustable collimator 100. The drive motors 40 are connected with the lead screws 30, the controller is used for controlling the drive motors 40 to drive the lead screws 30 to drive the corresponding blades to move along the plane of the cutting ray so as to form a first irradiation field through which the ray can pass. Wherein, the adjustable collimator 100 is of a regular cuboid structure internally provided with an accommodating space, and two sets of lead screws 30 are oppositely arranged at opposite positions inside the inner accommodating space of the inner side of the adjustable collimator 100. The lead screws 30 are cylinders arranged in parallel, the ends, close to the side wall of the adjustable collimator 100, of the lead screws 30 are connected with the drive motors 40 through connecting pieces, the ends, close to the center of the adjustable collimator 100, of the lead screws 30 are correspondingly connected with the end faces of the blades of the blade sets 20 in an adhesive bonding or buckle manner, and two sets of a plurality of oppositely arranged parallel line connecting bodies are formed inside the accommodating space of the adjustable collimator 100. The two sets of drive motors 40 are arranged on the outer surface of the side wall of the adjustable collimator 100 in an equally-spaced manner. Each drive motor 40 is independently connected to one lead screw 30 through a connecting piece. Each of the drive motors 40 can be independently controlled by the controller arranged outside the side wall of the adjustable collimator 100 to drive the lead screws 30 to move along the plane of the cutting ray. The blades in the two blade sets 20 can be controlled to move according to a preset control command of the controller, and different sizes or shapes of first irradiation field holes 70 are formed together so as to adjust the position, size and ray dosage of the first irradiation fields, of the first irradiation field holes 70 in the middle of the two blade sets 20 inside the adjustable collimator 100, through which the ray can pass. In this embodiment, for facilitating the position, size and ray dosage requirements of different rays during radiotherapy, the drive motors 40 can be controlled by the controller to drive the lead screws 30 and the blade sets 20 to move and adjust along the plane of the cutting ray. In this way, the first irradiation field hole 70 meeting the actual therapeutic ray can be formed, a conformal irradiation focus point with expected size and ray dosage can be formed when the ray passes through the first irradiation field holes 70, precise therapy on diseased parts is achieved, and the therapeutic effect of radiotherapy is improved. As shown in FIG. 1-FIG. 3, in this embodiment, in order to quickly adapt and adjust the size and ray dosage requirements of different rays, the two sets of opposite blades 50 at the central positions of the blade sets 20 are arranged to be small irradiation field blades. As an optimized embodiment, the widths of the small irradiation field blades 50 are greater than those of other blades. Further, the end faces, close to the center of the adjustable collimator 100, of the blades 50 are arranged in the shapes of circular arcs or polygons. For example, the irradiation field holes on the small radiation field blade may have different hole diameters. For example, as shown, at least one second irradiation field hole 60 with different sizes can be provided on the small irradiation field blade 50. The at least one second irradiation hole 60 can be arranged on the small irradiation field blade 50 in a size order or in an equally-spaced manner as shown. The second irradiation field holes 60 further can be arranged from the central position of the small irradiation field blade 50 to the two sides of the small irradiation field blade 50 in size order sequentially as also shown. The controller is further used for controlling the drive motors 40 to drive the second irradiation field hole 60 with expected size in the small irradiation field blade 50 to move below the ray so as to form the second irradiation field through which the ray can pass. The ray can pass through the second irradiation field hole 60 with expected size to form the conformal irradiation focus point with expected size and ray dosage, and precise therapy on diseased parts is achieved. The required second irradiation field holes 60 with different sizes can be flexibly arranged and selected in advance according to the requirements of actual radiotherapy, the size and ray dosage of the irradiation field target spot of the adjustable collimator 100 through which the ray can pass are quickly adjusted, precise therapy is achieved, and the work efficiency and therapeutic effect of radiotherapy are improved. In this embodiment, the controller comprises a first control module and a second control module. Wherein, the first control module is used for controlling the blade sets 20 to move along the plane of the cutting ray so as to form the first irradiation field through which the ray can pass when the expected irradiation field is relatively large. The second control module for controlling the second irradiation field hole 60 with expected size in the small irradiation field blade 50 to move below the ray so as to form the second irradiation field when the expected irradiation field is relatively small. For facilitating the position, size and ray dosage requirements of different rays during radiotherapy, the blade sets 20 can be controlled by the first control module to move according to actual requirement so as to form the conformal irradiation focus point with expected size and ray dosage in the first irradiation field. When therapy needs a small irradiation field with specific or small size, the small irradiation hole 50 also can be controlled by the second control module to form the smaller irradiation field of the second irradiation field. In this way, the therapy irradiation focus point with expected ray dosage, high precision therapy is quickly realized, and the work efficiency and therapeutic effect of radiotherapy are improved. It needs to be illustrated that, the first irradiation field is formed through the blades, particularly when the small irradiation field is formed, the half shadow of the ray is larger, through holes in the blades are in the second irradiation field, and the half shadow of the second irradiation field relative to the first irradiation field is smaller, so that when the small irradiation field is formed, therapy can be carried out by using the second irradiation field formed by the small irradiation field blades preferably, and the therapeutic effect is improved. Shown in FIG. 3, is another embodiment of the present invention that provides a collimation system that includes a collimator illustrated in FIG. 2. It will be described with reference to FIG. 2. In some embodiments, the collimation system comprises a shielding body 110 (shown in FIG. 2), a radioactive source 90, a pre-collimator 80 and the adjustable collimator 100 in the embodiment. The radioactive source 90 is used for generating therapeutic rays such as gamma rays. The shielding body 110 (shown in FIG. 2) can be arranged on the outer side of the source body of the radioactive source 90, and can be used for sealing and shielding harmful ray radiation of the radioactive source 90. The pre-collimator 80 is arranged below a ray outlet of the radioactive source 90, and is used for preliminarily guiding the ray of the radioactive source 90 into the adjustable collimator 100. The adjustable collimator 100 is arranged below a ray outlet of the pre-collimator 80, the blade sets 20 are driven by the drive motors 40 to move along the plane of the cutting ray, and the position, size and ray dosage of the adjustable collimator 100 through which the ray passes can be quickly adjusted, so that precision therapy is quickly realized. For example, the collimation system provided by the present invention comprises the radioactive source, the radioactive source also can be used for generating X rays, the collimation system can realize conformal irradiation radiotherapy through the adjustable collimator, and due to the fact that the adjustable collimator also comprises the small irradiation field blades, the second irradiation field also can be formed by using the small irradiation field blades, and more precision therapy is realized. For example, the collimation system provided by the present invention comprises the radioactive source, the radioactive source can be used for generating X rays, the X rays can be divided into multiple beams through deflection, each beam is emitted through the corresponding adjustable collimator and focused in the same area, so that the collimation can be used for focusing therapy. Shown in FIG. 4, based on the embodiment(s) described above, is another embodiment of the present invention that provides a therapy head, the therapy head comprises a shielding body 110, a source body 120, a plurality of pre-collimators 80 and a plurality of adjustable collimators 100 which are installed from outside to inside in sequence, the source body 120 is internally uniformly provided with a plurality of radioactive sources 90, the radioactive sources 90 are arranged above the ray inlets of the pre-collimators 80, the adjustable collimators 100 are arranged below the ray outlets of the pre-collimators 80, each radioactive source 90 is provided with the corresponding pre-collimator and the corresponding adjustable collimator 100 respectively, the radioactive rays emitted by the radioactive sources 90 can pass through the pre-collimators 80 and the adjustable collimators 100 to be focused in the same area 130, the therapy head can be used for quickly adjusting the position, size and ray dosage of the adjustable collimators 100 through which the ray can pass, and precision therapy is quickly realized. It needs to be illustrated that FIG. 4 is the therapy head as an example, it is understandable that the therapy head in the embodiment may comprise a plurality of radioactive sources and a plurality of adjustable collimators, and the pre-collimators can be arranged and also cannot be arranged between the radioactive sources and the adjustable collimators. The therapy head can be a therapy head for emitting gamma rays, also can be a linear accelerator therapy head for emitting X rays, or other types of therapy heads. Certainly, according to the difference of therapeutic purposes, the area 130 can be similar to tumor size and shape and also can be focus point, and the shape and size of the area 130 in the embodiment are not restricted specifically. An embodiment of the present invention provides a radiotherapy device, the radiotherapy device comprises the adjustable collimator in the embodiment, the collimation system or the therapy head, and the position, size and ray dosage of the ray can be quickly adjusted by the radiotherapy device, so that precision therapy is quickly realized. Above all, according to the adjustable collimator, the collimation system, the therapy head and the radiotherapy device provided by the present invention, the blade sets are controlled by the controller to move so as to form the first irradiation field, the second irradiation field is formed by controlling the movement of the second irradiation field hole in the small irradiation field blade, and the first irradiation field or the second irradiation field can be quickly and flexibly formed according to the position, size and ray dosage of the actual therapeutic ray so as to achieve the conformal irradiation focus point with expected size and ray dosage, so that precise therapy on diseased parts is achieved, and the therapeutic effect of radiotherapy is improved. It should be understood that each component of the present invention can be realized by using hardware, software, firmware or the combination. In the embodiment, a plurality of steps or methods can be realized by using software or firmware which is stored in a storage device and is executed by an appropriate command executing system. For example, if the steps or methods are realized by using hardware, the steps or methods are the same in the another embodiment, and can be realized by using any one of the following technologies known in the field or the combination: a discrete logic circuit with a logic gate circuit for realizing a logic function for a data signal, a special integrated circuit with an appropriate combined logic gate circuit, a programmable gate array (PGA), a field-programmable gate array (FPGA) and the like. In the description of the specification, the description of the reference terms such as “one embodiment”, “some embodiments”, “example”, “specific example” or “some examples” indicates to be contained in at least one embodiment or example of the present invention in combination with specific characteristics, structures, materials or characteristics described by the embodiment or example. In the specification, the schematic expression for the above terms possibly indicates same embodiment or example. Moreover, the described specific features, structures, materials or characteristics can be combined in any of one or more embodiments or examples appropriately. Although the embodiments of the present invention have already been illustrated and described, various changes, modifications, replacements and transformations can be made by any person skilled in the art under the condition of without departing from the spirit and the scope of the present invention, and thus the scope of the disclosure should be restricted by claims and equivalent scopes thereof.
	abstract	In accordance with the present invention, there is provided an increased efficiency strainer system which is particularly suited for use in the emergency core cooling system of a nuclear power plant. In certain embodiments of the present invention, the strainer system includes one or more strainer cassettes or cartridges, with each such cassette or cartridge including a plurality of strainer pockets disposed in side-by-side relation to each other. In these embodiments, multiple cassettes or cartridges may be assembled together to form a strainer module of the strainer system. The strainer pockets of the cartridge each define an inflow end. Within the cartridge, or the module including multiple cartridges, the inflow ends of one or more of the strainer pockets may be enclosed by an elastic metal membrane. When in a closed position, the membrane prevents liquid flow into the corresponding strainer pocket via the inflow end thereof. The membrane remains closed when only a low pressure load is exerted thereon, but is deflected or deformed into an open position when a high pressure load is exerted thereon. The movement of the membrane to its open position effectively opens the corresponding strainer pocket, thus allowing for the flow of liquid into the interior of the strainer pocket via the inflow end thereof.
	claims	1. A scanning charged-particle microscope havinga charged-particle source,a lens for focusing a charged-particle beam emitted from said charged-particle source, anda scanning deflector for scanning said charged-particle beam in two-dimensional form on a sample,wherein said scanning charged-particle microscope includes a passage aperture for limiting the passage of the charged-particle beam is located between the charged-particle source and said scanning deflector, and a member for limiting the passage of the charged-particle beam is provided at least in the center of said passage aperture,said lens focusing the charged particle beam such that a plurality of differential parts of the charged particle beam passing through the passage aperture converges one point on the sample simultaneously,said scanning deflector scanning the converged charged particle beam, andan image of said sample is obtained by scanning said charged-particle beam having passed through said passage aperture on said sample using said scanning deflector. 2. A scanning charged-particle microscope as set forth in claim 1 above, wherein the scanning charged-particle microscope has the half-opening angle of said aperture for said charged-particle beam focused on a sample by said focusing lens has a band with respect to specific values of αa and αb. 3. A scanning charged-particle microscope as set forth in claim 1 above, wherein the scanning charged-particle has said passage aperture is formed in a plate-like body, and in that said plate-like body is formed movably with respect to said charged-particle beam. 4. A scanning charged-particle microscope as set forth in claim 3 above, wherein the scanning charged-particle microscope has said plate-like body is provided with a circular aperture in addition to said passage aperture. 5. A scanning charged-particle microscope having a charged-particle source,a lens for focusing a charged-particle beam emitted from said charged-particle source on a sample with a half-opening angle which defines an irradiation angle of the charged particle beam against an optical axis of the charged particle beam,a scanning deflector for scanning said charged-particle beam in two-dimensional form on a sample,wherein said scanning charged-particle microscope includes a member located between the charged-particle source and said scanning deflector, the member having a limiting part which limits the charged particle beam having the half-opening angle being from zero degrees to αb degrees and allows the charged-particle beam having the half opening angle being from αb to αa degrees (αa>αb) to pass the membersaid lens focusing the charged particle beam such that a plurality of differential parts of the charged particle beam having the half opening angle being from αb degrees to αa degrees converges one point on the sample, simultaneously,said scanning deflector scanning the converged charged particle beam, andan image of said sample is obtained by scanning said charged-particle beam which is cut off, the half opening angle being from αb degrees to αa degrees. 6. A scanning charged-particle microscope as set forth in claim 5 above, wherein the scanning charged-particle microscope has a plate-like aperture body in which an annular aperture is formed is provided between said charged-particle source and said scanning deflector. 7. A scanning charged-particle microscope as set forth in claim 6 above, wherein the scanning charged-particle microscope has in addition to said annular aperture, a circular aperture is provided in said plate-like aperture body, and in that there is provided a movement feature for positioning said annular aperture and said circular aperture on the orbit of said charged-particle beam.
	abstract	A control rod drive contains a drive housing, in which a control rod carrying element is moveable between a basic position and an end position. The control rod carrying element is guided over a portion in a throttle bush. Formed across the throttle bush is a free flow cross section for a pressure fluid which varies in dependence on a position of the control rod carrying element. During an emergency shutdown, in which the control rod carrying element is moved hydraulically via a pressure fluid, the flow resistance for the pressure fluid is reduced, when the control rod carrying element reaches the end position. Therefore, a braking of the control rod carrying element takes place before it reaches the end position, thus reducing mechanical loads during braking. A flow resistance change takes place via a variable outside diameter of the control rod carrying element and/or by a bypass orifice.
	description	This invention relates to an apparatus for evaluating EUV (extreme ultraviolet) light source and an evaluation method using the same. More particularly, the invention concerns an EUV light intensity distribution measuring apparatus and an EUV light intensity distribution measuring method to be used in such apparatus, for performing evaluation of an EUV light source used in a projection exposure apparatus, for example. Conventionally, production of fine semiconductor devices such as semiconductor memories or logic circuits uses a printing (lithographic) process which is based on reduction projection exposure using ultraviolet rays. The smallest size that can be transferred by the reduction projection exposure is proportional to the wavelength of light used and it is inversely proportional to the numerical aperture of the projection optical system. Hence, in order to enable transfer of very fine circuit patterns, the wavelength of light to be used has been shortened more and more, such as from Hg lamp i-line (wavelength 365 nm) to KrF excimer laser (wavelength 248 nm) and then to ArF excimer laser (wavelength 193 nm), for example. However, semiconductor devices are being extremely decreased in size, and there is a limit in the lithography using ultraviolet light described above. In order to enable efficient printing of an extraordinarily fine circuit pattern less than 0.1 μm, reduction projection exposure apparatuses using extreme ultraviolet (EUV) light of a wavelength of about 10-15 nm, much shorter than the ultraviolet rays, are being developed. FIG. 11 illustrates such EUV exposure apparatus. As shown in FIG. 11, the exposure apparatus comprises an exciting pulse laser 101, a condensing lens 102 and a target supplying device 103. Denoted at 104 is plasma, and denoted at VC is a vacuum container. The container VC accommodates therein the following components: that is, illumination system first mirror 105, optical integrator 106, illumination system second mirror 107, view angle controlling aperture 108, illumination system third mirror 109, alignment detecting optical system 110, autofocus detecting optical system 111, reticle stage RS, reticle chuck RC, reticle R, projection system first mirror 112, projection system second mirror 113, projection system third mirror 114, opening controlling aperture 115, projection system fourth mirror 116, alignment detecting optical system 117, focus detecting optical system 118, wafer stage WS, wafer chuck WC, wafer W, and so on. In parallel to the development of this type of reduction projection exposure apparatuses, EUV light sources to be used with such apparatuses have been developed. An example is a laser plasma light source such as disclosed in Japanese Laid-Open Patent Application, Publication No. 2002-174700, corresponding to U.S. Pat. No. 6,324,256. This light source is arranged so that pulse laser of high intensity is projected on a target material placed inside a vacuum container to produce high-temperature plasma. The plasma functions as a light emission point from which EUV light of a wavelength of about 13 nm, for example, is emitted. As regards the target material, metal thin film, inactive gas or liquid drops are usable. The target material is supplied into the vacuum container by means of gas jet, for example. In order to assure that the EUV light emitted from the target has higher average intensity, the repetition frequency of the pulse laser should be made higher and, usually, the laser is operated at a repetition frequency of a few kHz. Optical elements are used to ensure efficient utilization of EUV light produced from the target. As regards the optical elements that constitute an exposure apparatus using EUV light, mainly they are oblique-incidence total reflection mirrors and also multilayered film mirrors made of silicon and molybdenum, as mirrors having an incidence angle close to normal incidence. Such normal incidence multilayered film mirror has high reflectance with respect to EUV light of 13.5 nm wavelength. Thus, among the light rays emitted from the EUV light source, EUV light in a range from 13.365 nm to 13.635 nm about the wavelength 13.5 nm can be used as a consequence, during the projection exposure process. The EUV light from the light emission point is collected by a collecting mirror at a light convergent point and, after subsequently diverging from the light convergent point, it is introduced into the projection exposure apparatus. Then, through an illumination optical system of the projection exposure apparatus, it illuminates a mask uniformly. Uniformly illuminating the mask is very important for the performance of the projection exposure apparatus such as resolving power, for example. To assure this, the light convergent point (spot) should desirably be formed at a predetermined position and with a certain extension not larger than a predetermined size, and also the EUV light should desirably be diverged from the light convergent point with good symmetry. However, due to various factors such as the shape of the plasma, the gas density distribution inside the vacuum container, and the shape of collecting mirror used, for example, the EUV light diverging from the light convergent point is not always idealistic. Therefore, it is desirable to detect the position, size, shape and the like of the light convergent point of a used EUV light source and to correct it by use of an illumination optical system. In order to measure the position, size, shape and the like of a light convergent point, it is necessary to measure the intensity distribution inside an image that is formed by imaging the EUV light from a light convergent point through an optical system. An example of such an imaging optical system for imaging the EUV light having short wavelength is a Schwarzschild optics which is constituted by use of multilayered-film mirrors. However, the following inconveniences are present in relation to measurement of the intensity distribution of an image as imaged by use of an imaging optical system having multilayered-film mirrors. The intensity of EUV light generally required as EUV light source is only about 100 W. However, since the EUV light source contains light rays of wavelength regions such as visible light or infrared rays which are basically unnecessary for the exposure process, the quantity of light that actually passes the light convergent point and enters the imaging optical system becomes more than 1 kW. On the other hand, the multilayered film mirror of the imaging optical system is designed so as to reflect only the wavelength region that is necessary for the EUV light exposure. Therefore, much of energies incident on the mirror is absorbed by the mirror and it heats the mirror. The optical system for EUV light is placed in a vacuum and, furthermore, direct water cooling is very difficult because of vibration. Thus, it is practically difficult to cool the mirror efficiently. As a result, the temperature of the multilayered film mirror rises, and resultant thermal deformation causes an error in shape. Furthermore, the structure of the multilayered film may be destroyed, causing decrease of reflectance. On the other hand, there is another problem. While CCD or the like may be used as a detector for measuring the intensity distribution of an image, being imaged through an imaging optical system, if the intensity of light impinging on the detector is too large, the output of the detector will be saturated. Accurate measurement is unattainable in such occasion. Such a problem may be solved by using a filter for attenuating the light quantity. However, in order that a metal thin film can be used as a filter, for example, it should be made with a thickness of about a few microns. With such thickness, the film may be easily fused by heat or the filter may have non-uniform transmittance. For these reasons, it is very difficult to use such filter practically in the measurement. It is accordingly an object of the present invention to provide a measuring apparatus by which the position, size and/or shape of a light convergent point of an EUV light source can be measured precisely. It is another object of the present invention to provide a measuring method that uses the measuring apparatus described above. In accordance with an aspect of the present invention, there is provided a measuring apparatus, comprising: light receiving means for receiving EUV light diverging from a light convergent point; an optical system for directing the EUV light toward said light receiving means; a light blocking member disposed in a portion of light path for the EUV light and having a plurality of openings; and means for detecting a spatial distribution of the EUV light at the light convergent point, on the basis of reception of EUV light by said light receiving means. In accordance with another aspect of the present invention, there is provided a measuring apparatus, comprising: light receiving means for receiving EUV light diverging from a light convergent point; a gas filter disposed in a portion of a light path of the EUV light and being filled with a predetermined gas; and means for detecting a spatial distribution of the EUV light at the light convergent point, on the basis of the reception of EUV light by said light receiving means. These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings. Preferred embodiments of the present invention will now be described with reference to the attached drawings. FIG. 1 shows a measuring apparatus 14 according to a first embodiment of the present invention, for measuring a spatial distribution, such as position, size, shape and the like, of a light convergent point of an EUV light source. FIG. 1 illustrates the measuring apparatus 14 in the state in which it is mounted to an EUV light source 17 to be measured. The EUV light source 17 projects pulse laser light upon a target material by which, or by exciting gas molecules through electric discharging, plasma that emits light rays 1 including EUV light is produced at a light emission point 20. A light collecting mirror 16 comprising a rotational ellipsoid mirror is disposed with its one foal point placed at or adjacent the position of the light emission point 20, and it functions to collect the light rays 1, emitted from the light emission point 20, to and at the position of another focal point thereof. In FIG. 1, the position of a light convergent point 2 corresponds to one focal point position of the light collecting mirror 16. The light rays 1 collected at the light convergent point 2 diverge therefrom while taking the light convergent point as a secondary light source. Where the light rays are to be used for exposure, the light rays are directed to an illumination optical system of an exposure machine. Where the EUV light source is used as an exposure light source, it is desirable that the light convergent point 2 is exactly defined at a predetermined position and it has symmetrical intensity distribution, such that a symmetrical intensity distribution is produced within a divergent angle from the light convergent point 2. Furthermore, in order to suppress various aberrations at the illumination optical system of the exposure machine, it is desirable that the size of the light convergent point should be kept at not greater than a predetermined level. However, since the light convergent point 20 is defined by plasma which can be produced in various ways as described above, the position, size, and distribution and so on of the light convergent point can not always be idealistic. Furthermore, since the light convergent point 2 is defined by imaging the light emission point 20 by means of the light collecting mirror 16, any errors in shape of the light collecting mirror 16 or a distribution of reflectance thereof may cause variation in spatial distribution such as position, size or distribution. Taking theses factors into consideration, it would be readily understood that, for satisfactory exposure, it is very important to measure the position, size or distribution of an actual light convergent point by use of the measuring apparatus 14 of the present invention, to assure a predetermined condition. The measuring apparatus 14 of the present invention which is a spatial distribution evaluation apparatus for the light convergent point 2, comprises a Schwarzschild optics including a first mirror (concave mirror) 3 and a second mirror (convex mirror) 4 that functions to image, with enlargement, the light rays 1 diverging from the light convergent point 2, upon a screen 8. Here, the first and second mirrors 3 and 4 comprise a multilayered film mirror having been formed by providing a multilayered film by vapor deposition upon the surface of a substrate being formed into concave shape or convex shape. An example of multilayered film mirror to be used with EUV light of a wavelength of about 13.5 nm is one having alternate layers of Mo and Si and being designed to reflect EUV light of wavelengths in a range of ±0.5 nm about a peak wavelength 13.5 nm. Where the interface between Mo and Si is rough, a buffering material effective to reduce the surface roughness may be provided between Mo and Si. An example of such buffering material may be B4C. The EUV light which is the object of measurement can be attenuated largely by gas molecules. It is therefore desirable to keep a vacuum ambience inside a chamber 15 in which the light path of EUV light is defined. In this embodiment, the screen 8 comprises a glass substrate 10 having a fluorescent substance 9 formed thereon. The EUV light absorbed by the fluorescent substance 9 is converted into fluorescent light which is visible light having a wavelength peculiar to the fluorescent substance. By imaging it upon a CCD 13 placed in an atmosphere, through the glass substrate and a view port 11 which is a vacuum window, an image of the light convergent point can be measured. Alternatively, a CCD may be directly disposed as a screen 8 to observe the EUV light. In this embodiment, a light attenuating plate 5 is inserted between the light convergent point 2 and the first mirror 3, while a gas filter 7 is interposed between the second mirror 4 and the screen 8. FIGS. 2 and 3 illustrate the shapes of openings that can be formed in the light attenuating plate 5. The light attenuating plate 5 may desirably be provided by forming pinhole-like openings (FIG. 2) or slit-like openings (FIG. 3) in a light-blocking plate effective to intercept light. Particularly, where the light rays diverging from the light convergent point 2 have an intensity distribution of circular shape at the position of the light attenuating plate 5, use of pinhole-like openings shown in FIG. 2 will be appropriate. If the intensity distribution has a ring-like shape, use of slit-like openings shown in FIG. 3 will be appropriate. The light attenuating plate should desirably be disposed at a position that can not be image upon the screen 8. Particularly, in order to assure that the intensity distribution within the light convergent point does not change regardless of use of the light attenuating plate and that the light rays emitted from each positions are attenuated uniformly, the light attenuating plate should desirably be disposed on a pupil plane of the optical system inside of the measuring apparatus 14. As regards the width or diameter d of the openings of the light attenuating plate 5, when the distance between the light convergent point and the openings of the light attenuating plate 5 is denoted by L, the wavelength is denoted by λ, and a desired resolving power is denoted by R, from the Rayleigh limit there is a relation R=0.61λ/(0.5 d/L) and, hence, any decreases of the resolving power due to the openings of the light attenuating plate 5 can be avoided if relation (1) below is satisfied.d>1.22·λ·L/R (1) Particularly, where any changes of the centroid position of the light convergent point 2 should be measured, it will be enough that the resolving power R is about ⅕ of the diameter D of the light convergent point. Hence, a width d satisfying relation (2) below will be sufficient.d>6.1·λ·L/D (2) For example, when the light attenuating plate 5 is placed at a position of 150 mm from the light convergent point, if the EUV light to be measured has a wavelength 13.5 nm and the resolving power required is 0.1 mm, a diameter of the openings not less than 25 μm will be enough. In this embodiment, openings of a diameter 100 μm are formed with a pitch 2 mm, and thus an attenuation rate of 0.002× is accomplished without a decrease of resolving power. By using a light attenuating plate 5 having a predetermined opening as light attenuating means as described above, a desired attenuation rate can be accomplished. Furthermore, as compared with a case where a thin film filter is used, a thick plate having better heat conductivity can be used, yet the attenuation rate distribution along the surface can be made more uniform. FIG. 4 illustrates the structure of the gas filter 7. The light entrance side of the gas filter 7 is defined by a thin film being transmissive to EUV light. The opposite side of the gas filter is defined by the screen 8. The inside space may be filled with Xe gas, for example, and EUV light can be attenuated thereby. The inside pressure of the gas filter 7 is controlled by pressure controlling means (not shown) connected to the gas filter 7 through a gas supplying tube. In this embodiment, the gas filter 7 and the screen 8 are made integral. However, they may be provided separately. In that occasion, in place of the screen 8, a window being transmissive to EUV light may be provided at the light exit side to gas-tightly keep the gas inside the filter. FIG. 5 illustrates the relationship (line 30) between the Xe gas pressure and the transmittance of light of 13.5 nm under a condition that the temperature is 300K and the optical path length in the gas is 50 mm. It is seen from FIG. 5 that, under a constant temperature, by controlling the gas pressure, the intensity of light transmitted can be attenuated from one-digit level to six-digit level. Since the transmittance is a function of number density, if the temperature is variable, the control may be carried out to the pressure P and the temperature T to maintain P/T at a predetermined value. The gas filter 7 should have a window for gas-tightly keeping a gas in the filter. Since such window should have a function for transmitting EUV light at a predetermined transmittance, it would be necessary to provide such window by use of a thin film. If the gas filter pressure increases, therefore, the window will be flexed by the gas pressure. This means that the transmittance becomes different depending on the position where the light ray passes. In order to avoid this, a thin film being supported by a mesh structure provided by a matrix-like frame may be used as the gas filter window. In that occasion, in order to avoid that the shadow of the supporting mesh causes non-uniformness of the intensity upon the screen, the supporting mesh should desirably be placed at a predetermined distance or more away from the screen. The distance L2 with which the shadow of the mesh when projected on the screen 8 would not cause any inconveniences can be determined as follows. The condition for the distance L2 ensuring that the distance D through which the light ray slices on the mesh is 10 times larger or more of the pitch P of the mesh can be expressed by relation (3) below, if the numerical aperture of the optical system is NA and the magnification is M.L2>5·p·M/NA (3) With the provision of a gas filter window 6 with mesh as described above, a sufficient number of mesh frames can be present both in the path of a light ray emitted from a point A and in the path of a light ray emitted from another point B. It is assured therefore that the supporting mesh does not cause non-uniform intensity on the screen 8. As an example of combination of a window 6 and a supporting mesh, a window 6 may be provided by using a Zr thin film of 0.2 μm thickness, effective to transmit 13.5 nm light by 50%, and it may be supported by a supporting mesh consisting of a grid-like Ni frame having 30 μm thickness. The mesh may have a pitch 0.3 mm. When an optical system having a NA=0.1 and a magnification 2.5× is used, it is seen from the relation (3) above that the shadow of the mesh is not observed upon the screen 8 if the distance L2 from the window 6 to the screen 8 is made not shorter than 37.5 mm. Furthermore, by controlling the gas (Xe) pressure inside the gas filter 7 in a range from 0 Pa to 1500 Pa, the transmittance can be controlled within a range from 0.5 to 0.0001. Here, it should be noted that the Zr film serves to completely block visible light. Thus, it functions also as a visible light removing filter. Where a thin film filter is used, non-uniformness of its thickness may cause a difference in the transmittance of EUV light. In the case of Zr filter, for example, a thickness non-uniformness of ±0.1 μm may cause ±30% non-uniformness of transmittance. Like the case of the mesh support, if much film thickness irregularity is present at the position where the light rays to be incident on a single point on the screen cross the thin film filter, the intensity non-uniformness due to the film thickness non-uniformness is not observed upon the screen. The positional relationship between the thin film filter and the screen corresponds to the product of equation (3) multiplied by the non-uniformness of transmittance. If the pitch of non-uniformness is p, the numerical aperture of the optical system is NA, the magnification is M, the distance from the filter to the screen is L3, the average period of the transmittance non-uniformness is PV, the thin film filter may be disposed at a position that satisfies relation (4) below and, in that occasion, non-uniformness of intensity due to the film thickness non-uniformness is never observed upon the screen.L3>5·p·PV*M/NA (4) As an alternative, the thin film filter may be disposed between the mirror and the light convergent point. In that occasion, M=1 may be chosen and the filter may be disposed at a position that satisfies relation (5) below.L3>5·p·PV/NA (5) If the temperature rise of the thin film filter is a problem to be considered, a thin film being supported by a grid-like supporting mesh having a thickness of tens microns and a pitch of hundreds microns may be used. In that occasion, the heats can be released through the supporting mesh to the frame member of the supporting mesh. Thus, temperature rise of the thin film can be prevented. In that occasion, in order to assure that the shadow of the supporting mesh from is not projected on the screen, the thin film filter may be disposed at a position that satisfies the relation (3) mentioned above. Furthermore, by circulating a gas through the gas filter 7, the heat of the window can be removed efficiently. As regards the light attenuating plate 5, the gas filter 7, the window 6 of the gas filter 7, and the mesh support for it, the structures described above are not the sole example. They may be modified appropriately to provide different transmittance. Furthermore, the position for the light attenuating plate 5 and the gas filter 7 is not limited to those described above. The position may be determined appropriately while taking into account the light intensity at various positions along the light path, for example. By us of the light attenuating plate 5, the intensity of light rays impinging on the first and second mirrors 3 and 4 can be made sufficiently small, and thus unwanted damage of the mirrors can be avoided effectively. Furthermore, by use of the gas filter 7, a transmittance to be harmonized with the intensity sensor, provided on the screen 8, can be realized. While this embodiment has been described with reference to an example wherein Schwarzschild optics is used as an imaging optical system, the imaging optical system may be an eccentric or decentered optical system having a reflection mirror. A second embodiment of the present invention will be described with reference to an example wherein a mixture gas of Xe and SF6 is used as a gas of the gas filter 7. FIG. 6 illustrates the transmittance of xenon Xe, sulfur hexafluoride SF6 and a mixed gas of them (mixing ratio of SF6:Xe is 0.55:0.45), with respect to light of wavelengths 12-14 nm. For all cases, the optical path length is 40 mm, and the pressure is 400 Pa. The wavelength is taken on the axis of abscissa, while the transmittance is taken on the axis of ordinate. It is seen from FIG. 6 that, for a single gas of Xe or SF6, the transmittance varies in dependence upon the wavelength; whereas if a mixed gas of Xe and SF6 is used, a gas filter having a transmittance being small in wavelength dependency can be provided. Although FIG. 6 shows the wavelength dependency of the transmittance in regard to a gas having a mixture ratio of 55% SF6 vs. 45% Xe, a gas filter having approximately uniform transmittance within a range of 13 to 14 nm can be provided if a mixed gas that contains 40% to 60% Xe is used. The gases usable as the mixed gas of the gas filter are not limited to Xe and SF6. By using gases having positive and negative differential coefficients, respectively, to the wavelength, of the absorption coefficient in the wavelength region concerned at an appropriate density ratio, a gas filter with transmittance having small dependency upon the wavelength can be accomplished. A third embodiment of the present invention will be described with reference to an example wherein a mixed gas of Xe and Kr is used as a gas for the gas filter 7. FIG. 7 shows the spectral intensity in a case where a gas which contains krypton Kr is used for the gas filter 7, in relation to EUV light being reflected by a Schwarzschild optics having multilayered film mirrors. Where a Schwarzschild optics such as shown in FIG. 1 is used to image the EUV light, a multilayered film mirror is used as the reflection mirror. Since a multilayered film mirror has a characteristic for diffracting and reflecting light of a particular wavelength being incident with a particular incidence angle, into a particular direction, the light rays being reflected thereby have an intensity distribution having a peak at a predetermined design wavelength. However, regarding the EUV light having been reflected by the Schwarzschild optics wherein the number of layers of the multilayered film is made small to ensure uniform reflectance to the EUV light at any positions on the mirror as in the measuring apparatus of the present invention, as shown by spectral intensity curve 31 in FIG. 6 it has an intensity with relatively wide wavelength, with respect to a range from 13.365 nm to 13.635 nm practically usable in the exposure process. Because of this, there is a possibility that the result of measurement of the spatial distribution of the EUV light does not match the spatial distribution of EUV light actually used in the exposure process. On the other hand, as depicted by an absorption curve 33, Kr has strong absorptions at opposite sides of 13.5 nm. Therefore, if Kr is used in the gas filter 7 in relation to EUV light having a spectral intensity 31, a spectral intensity shown at 32 having an enhanced portion around 13.5 nm is obtainable. Hence, information more pertinent to actual exposure wavelength can be provided. Furthermore, as shown in FIG. 6, Xe has a relatively flat absorption characteristic in the neighborhood of 13.5 nm. Therefore, if a gas filter 7 having Kr and Xe, being effective to produce selective absorption such as described above, at respective partial pressures predetermined, is used, both the attenuation rate adjustment and the wavelength selection can be done at once. Particularly, a spatial distribution of the intensity of the wavelength about 13.5 nm actually to be in the exposure process can be produced. Although this embodiment uses a mixed gas of Kr and Xe, a mixture gas in which Kr is added to the mixture of Xe and SF6 as used in the second embodiment, may be used. A fourth embodiment of the present invention will be described with reference to a method of improving the measurement precision in the measurement of a spatial distribution of the light convergent point 2 using a measuring apparatus 14 such as described hereinbefore. FIG. 8 shows a measuring apparatus according to this embodiment of the present invention, in which a tiltable chart plate 18 for calibration of measurement is provided at the position of the light convergent point 2. This chart plate 18 comprises a light blocking plate having openings, and it is demountably mountable on the light path. For calibration of measurement, it is mounted on the light path. FIG. 9 illustrates grid-like openings (pinholes) 19 which are formed in the chart plate 18. A method of measuring the spatial distribution of the light convergent point 2 with good precision, by use of the chart plate 18, will now be described. First, the light source is actuated to emit light, while the chart plate 18 is held placed on the optical axis to enable the light beam 1 to pass through the pinhole 19 and is imaged on the screen 8. Then, the position of the image of the pinhole 19 is detected. Here, from the relationship between the actual position of the pinhole 19 and the position of the image of the pinhole 19 formed on the screen 8, overall image distortion throughout the imaging optical system and the CCD optical system can be detected. Subsequently, the chart plate 18 is demounted out of the optical axis, and an image of the light convergent point 2 is imaged on the screen in the manner as has been described with reference to the first embodiment, and the spatial distribution of the light convergent point is measured. Here, by taking into account the optical distortion from the light convergent point to the screen 8 having been detected as described above, the image of the light convergent point can be detected very accurately. Hence, any distortion of the image caused in the measurement procedure can be corrected in the manner described above. Thus, even if thermal deformation, for example, of the imaging optical system occurs during the measurement, the image of the light convergent point can be detected accurately and correctly. The chart plate 18 may preferably be provided at the light convergence (collection) position of the light collecting mirror 16. If the chart plate 18 has a thickness to certain extent, the surface thereof at the light entrance side may preferably be set at the light convergence position, while the sectional structure of the pinholes 19 may preferably be made such as shown in FIG. 10, wherein it has a shape extending with a predetermined angle or more along the optical axis direction. Here, the extending angle θ of the pinhole 19 can be given by relation (6) below, if the angle of the light source which is the object of measurement is NA.θ>2·arcsin(NA) (6) It is to be noted here that the openings to be formed in the chart plate 18 are not limited to pinholes. Slits or the like may be used. While the invention has been described with reference to the structures disclosed herein, it is not confined to the details set forth and this application is intended to cover such modifications or changes as may come within the purposes of the improvements or the scope of the following claims. This application claims priority from Japanese Patent Application No. 2004-078588 filed Mar. 18, 2004, for which is hereby incorporated by reference.
052280691	abstract	A CT scanner using a rotate-rotate mode wherein the detector is designed to simultaneously detect X-rays that have traversed multiple-planar sections in a patient being scanned.
	summary
039716996	abstract	1. The method of operating a water-cooled neutronic reactor having a graphite moderator which comprises flowing a gaseous mixture of carbon dioxide and helium, in which the helium comprises 40-60 volume percent of the mixture, in contact with the graphite moderator.
043437621	description	DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, the invention comprises a tungsten reinforced, refractory ceramic bottle 10. A fuel core assembly 12 is suspended in the top of neck 14 of bottle 10. A vertical array of baffle sets 16 extends from under the fuel core assembly to the base 17 of said bottle 10. Beginning with a first baffle set 26, the next with 2 or 3 baffles 19 and each baffle set therebelow has double the number of baffles as the one immediately above it (see FIGS. 2 or 3). The number of baffle sets 16 is determined by the amount of nuclear fuel in the core assembly 12 so as to divide it into the relatively safe fuel pellet masses in which nuclear fuel is shipped. Bottle 10 comprises a body 20 having a cylindrical lower part 22 and frustoconical upper part 24 fixed to the neck 14. Baffle sets 16 are supported and arranged in bottle 10 as shown in FIG. 1, with three baffle sets 26-28 supported in bottle neck 14, and three baffle sets 29-31 supported in the bottle body 20 on base 17, and which support neck baffle sets 26-28. All of the baffle sets 16 are cylindrical except for baffle set 31 which is annular in shape to define a center space 32 in which a heat exchanger (not shown) may be mounted. An impact plate 34 covers space 32 which is greater in diameter than the remainder of the baffle sets, and thus slopes upwardly to a center cone 36 that extends from the impact plate upwardly into baffle sets 30 and 29 which are adapted to engage therearound. Space 38, defined in the conical upper part 24 of bottle 10 by bottle baffle sets 29-30, center cone 36, and impact plate 34, provides for gas expansion and containment of radioactive gas products of the melt-down. Referring to FIGS. 2 and 3, the second baffle set 27 can be comprised of two or three baffles, depending on the available space and the mass of nuclear fuel in the core assembly. By doubling the number of baffles 19 begining with one baffle in the baffle set 29, there will be 32 baffles in set 31. If upper set 27 begins with three baffles, then lower set 31 will have 48 baffles in the same number of sets below. In use, the invention functions to divide a melt-down mass of nuclear fuel into twice the number of masses for each set of baffles, at least, thru which it passes, thereby rapidly reducing the separate masses to below criticality and fissioning, and at the same time to absorb neutrons necessary for chain reaction fissioning. Expansion for radioactive gaseous products is provide in space 38, and cooling is provided in space 32. Thus all radioactive products of a melt-down are contained in bottle 10 and prevented from contaminating the environment, and fission of nuclear fuel is halted by division into less than critical masses halted prior to a nuclear explosion. It should be noted that center cone 36 and impact plate 34 direct the melt outwardly and downwardly into the most multitudinous baffles of the bottom annular baffle set 31.
	abstract	There are disclosed a collimator, a radiation emitting assembly and an inspection apparatus. The collimator is configured to collimate radiation from a radiation emitter. One of the collimator and the radiation emitter is provided with a protrusion portion and the other is provided with a recess portion such that the protrusion portion is capable of being placed within the recess portion and the radiation emitter and the collimator are allowed to be arranged close to and connected with each other, and that the radiation passes through passages in the protrusion portion and the recess portion from the radiation emitter to the collimator.
	abstract	An extreme ultraviolet (EUV) light generator includes a generation region where a target generates EUV light, a mirror that focuses the EUV light, an illumination light source, and a light receiver to receive reflected light from the target. A reflection surface of the mirror defines first and second focuses at the generation region and a mirror focal point, respectively. A line segment that links a reflection surface outer peripheral edge and the first focus is rotated about an axis through the first and second focuses to form a first limit surface. The line segment and an extended line on the outer peripheral side rotated about the axis forms a second limit surface. At least one of an illumination light optical path and a reflected light optical path from the light source and the light receiver, respectively, passes through the first focus and extends between the first and second limit surfaces.
	abstract	For the redistribution of a coolant flow from a first region into a second region, in particular in boiling-water-reactor fuel elements having an eccentrically disposed water passage, a fuel-rod bundle is constructed in a mirror symmetry manner relative to a diagonal. A distance between adjacent fuel rods increases monotonically in particular along a diagonal. In addition, a fuel-rod bundle as an entity may be offset eccentrically along the diagonal. To compensate for asymmetry in the reactor core, a redistribution of coolant is provided which is advantageous in pressurized-water-reactor fuel elements.
	claims	1. An apparatus for creating a pattern on a workpiece sensitive to light radiation, the apparatus comprising:a source for emitting electromagnetic radiation in a wavelength range from EUV to to IR;a spatial light modulator (SLM) having a plurality of modulating elements operable for being illuminated by said radiation;a projection system for creating an image of the modulator on the workpiece;an electronic data processing and delivery system for receiving a digital description of the pattern, converting said pattern to modulator signals, and sending said signals to the modulator;a precision mechanical system for positioning at least one of said workpiece and said projection system relative to each other; andan electronic control system controlling the position of the workpiece, such that said pattern is printed on the workpiece; whereinthe input pattern description is converted to modulator voltages for particular modulating elements to correct for variation among modulating elements using a lookup memory. 2. The apparatus according to claim 1, wherein the lookup memory is updated to compensate for changes in responses of the particular modulating elements. 3. The apparatus according to claim 2, wherein the lookup memory is updated iteratively. 4. The apparatus according to claim 2, wherein the changes are time dependent. 5. A method for creating a pattern on a workpiece sensitive to light radiation, the method comprisingemitting electromagnetic radiation on a spatial light modulator (SLM) having a plurality of modulating elements, the electromagnetic radiation being in a wavelength range from EUV to IR;creating an image of the SLM on the workpiece using a projection system;converting a received digital description of the pattern into modulator signals, the received digital description of the pattern being converted to modulator voltages for particular modulating elements to correct for variation among modulating elements using a lookup memory;sending said signals to the modulator;positioning at least one of said workpiece and said projection system relative to each other; andcontrolling the position of the workpiece, such that said pattern is printed on the workpiece. 6. The method according to claim 5, wherein the lookup memory is updated to compensate for changes in responses of the particular modulating elements. 7. The method according to claim 6, wherein the lookup memory is updated iteratively. 8. The apparatus according to claim 7, wherein the changes are time dependent.
	abstract	The use of carbamides as extractants for fully or partially separating uranium(VI) from plutonium(IV) in an aqueous solution obtained by dissolving a spent nuclear fuel in nitric acid, by method of liquid-liquid extraction, without carrying out any reduction of the plutonium(IV) to plutonium(III). The invention also relates to new carbamides. Uses are the processing of spent nuclear fuels based on uranium (especially uranium oxides—UOX) or uranium and plutonium (especially mixed uranium and plutonium oxides—MOX).
	summary
	claims	1. A method for a nuclear reactor safety related application, said method comprising:performing a first test of an application using application-specific logic implemented as hardware logic;performing a second test of the application using application-specific logic implemented as software for execution by microprocessor-based controlling software, each test executed with a same set of inputs;comparing a first test result produced from the execution of the hardware-implemented form of application-specific logic to a second test result produced from the execution of the software-implemented form of application-specific logic;when the compared results concur, performing actions associated with the concurring results by executing microprocessor-based software, such actions comprising:actuating external equipment that operate valves when the nuclear reactor is online or offline; andperforming subsequent equipment and software tests; andwhen the compared results fail to concur, reporting the failure of the compared results to concur to an operator by executing microprocessor-based software, and thereafter placing the microprocessor-based software into an inoperative (INOP) mode. 2. A method in accordance with claim 1 wherein the same application-specific logic is a nuclear reactor standby liquid control (SLC) application, said method further comprising controlling injection of a liquid into the reactor by the SLC application. 3. A method in accordance with claim 1 wherein the hardware-implemented form of application-specific logic is the control logic of at least one programmable logic device (PLD), and the result produced from the execution of the hardware-implemented form of application-specific logic is obtained by microprocessor-based software from reading status registers of the at least one PLD. 4. A method in accordance with claim 1 wherein the software-implemented form of application-specific logic is stored in EPROM memory located on a microprocessor card, the microprocessor card also including at least one microprocessor, RAM memory, non-volatile RAM (NVRAM) memory, and at least one programmable logic device (PLD) wherein the hardware-implemented form of application-specific logic is stored. 5. A method in accordance with claim 1 wherein the same set of inputs includes input signals from sensors and equipment external to operational hardware and software that provide for the execution of the application-specific logic. 6. A method in accordance with claim 5 wherein the input signals from sensors and equipment include nuclear reactor related signals in the form of anticipated transient without SCRAM (ATWS) input signals, analog trip module (ATM) input signals, tank level input signals, bypass unit input signals, and operational status signals from low voltage switch gear (LSWG) equipment. 7. A method in accordance with claim 1 wherein the performing actions associated with the concurring results include performing injection of a liquid into a nuclear reactor by operating relays associated with injection pumps, injection valves, overload bypass, and storage tank valves. 8. A method in accordance with claim 1 wherein the performing actions associated with the concurring results include halting of injection of a liquid into a nuclear reactor by operating relays associated with injection pumps, injection valves, overload bypass, and storage tank valves. 9. A method in accordance with claim 1 wherein, when in the INOP mode, software self tests are executed to test hardware and software associated with the execution of the application-specific logic to detect hardware and software faults, and results of the execution of the self tests are made available to an operator. 10. A method in accordance with claim 9 wherein contacts and relays are isolated during the execution of the software self tests to prevent operation of equipment external to the hardware and software associated with the operation of the application-specific logic. 11. A method in accordance with claim 1 wherein when hardware and software associated with operation of the application-specific logic is in standby operating (STANDBY) mode, as indicated by non-existence of critical faults and concurrence of the compared results, software self tests are executed to test the hardware and software associated with operation of the application-specific logic in order to detect hardware and software faults, and results of the execution of the self tests are made available to an operator. 12. A method in accordance with claim 11 wherein contacts and relays are isolated during the execution of the software self tests to prevent operation of equipment external to the hardware and software associated with operation of the application-specific logic. 13. A method in accordance with claim 11 wherein when critical faults are detected via the execution of the software self tests, the software-implemented form of application-specific logic and the microprocessor-based software are placed into the inoperative (INOP) mode by executing the microprocessor-based software. 14. A method in accordance with claim 1 wherein systems and equipment external to hardware and software associated with the execution of the application-specific logic are automatically actuated and tested for correct operation by the hardware and software associated with the operation of the application-specific logic, with results of the testing being made available to an operator. 15. A digital microprocessor-based system for a nuclear reactor safety related application, said system comprising:a microprocessor with memory, hardware, circuitry, and software programming that provides for execution of two forms of a same application-specific logic, and provides for performing a first test of an application using application-specific logic implemented as hardware logic and performing a second test of the application using application-specific logic implemented as software, the two tests executed with a same set of inputs;the same application-specific logic implemented in one of the two forms as hardware logic, and in another of the two forms as software instructions for execution by the microprocessor;the software programming further providing for comparison of a first test result produced from execution of the one of the two forms as hardware logic to a second test result produced from execution of the another of the two forms as software instructions;the software programming further providing, when the compared results concur, for the execution of actions associated with the concurring results, such actions comprising:actuating external equipment that operate valves when the nuclear reactor is online or offline; andperforming subsequent equipment and software tests; andwhen the compared results fail to concur, the software programming further providing for the reporting to an operator of the failure of the compared results to concur, thereafter the software programming further executing to place the microprocessor-based system into an inoperative (INOP) mode. 16. A system in accordance with claim 15 wherein the same application-specific logic is a nuclear reactor standby liquid control (SLC) application, said SLC application providing for control of injection of a liquid into the reactor. 17. A system in accordance with claim 15 wherein the hardware logic is the control logic of at least one programmable logic device (PLD), and the result produced from the execution of the hardware logic is obtained by microprocessor-based software from reading the status registers of the at least one PLD. 18. A system in accordance with claim 15 further comprising a microprocessor card with EPROM memory for storing the software instructions, at least one microprocessor, RAM memory, non-volatile RAM (NVRAM) memory, and with at least one programmable logic device (PLD) wherein the one of the two forms as hardware logic is implemented. 19. A system in accordance with claim 15 wherein the same set of inputs includes input signals from sensors and equipment external to the system, and wherein the software programming further provides software for receiving the external input signals. 20. A system in accordance with claim 15 wherein the execution of actions associated with the concurring results includes operating relays associated with equipment external to the system via software further provided by the software programming. 21. A system in accordance with claim 15 wherein the software programming further includes self tests for detecting faults in the hardware and software of the system and the software programming further provides, in conjunction with the system hardware, ability to isolate contacts and relays associated with equipment external to the system so as to prevent operation of the equipment during execution of the self tests.
	summary
	summary
	claims	1. A method of adjusting the pH of a stream of water in a water system of a power plant comprising:providing a pressurized stream of water in a water system of a power plant; andadding anhydrous ammonia into the pressurized stream of water via a vacuum eductor, wherein the pressurized stream of water in the water system of the power plant provides vacuum assistance for the introduction of the anhydrous ammonia. 2. The method according to claim 1, further including controlling the addition of anhydrous ammonia. 3. The method according to claim 2, wherein controlling the addition of anhydrous ammonia comprises controlling the rate of addition of anhydrous ammonia based on conductivity of the pressurized stream of water in the water system of the power plant. 4. The method according to claim 2, further including metering an amount of anhydrous ammonia added into the pressurized stream of water in the water system of the power plant. 5. The method according to claim 4, further including controlling hydraulic conditions of the pressurized stream of water in the water system of the power plant to create the vacuum. 6. The method according to claim 5, further including storing anhydrous ammonia in a storage assembly for addition into the pressurized stream of water in the water system of the power plant, wherein the storage assembly is positioned distant from the addition point. 7. The method according to claim 6, wherein the vacuum created by the flow of the pressurized stream of water through the vacuum eductor is the only assistance for the addition of the anhydrous ammonia from the storage assembly to the point of introduction into the pressurized stream of water in the water system of the power plant. 8. The method according to claim 6, wherein controlling the addition of anhydrous ammonia comprises a control system for use by an operator positioned distant the storage assembly.
	claims	1. A small nuclear fission reactor designed to operate for a decade or longer without refueling, which reactor comprises:a reactor vessel,a central core within said vessel for creating heat via fission reactions in said core, which core includes a plurality of initial fissile sections located in a plurality of vertically spaced apart horizontal regions, and flanking conversion sections, said a plurality of initial fissile sections remaining an active, integral part of a critical core region throughout the lifetime of the central core,a helium circulation system for extracting heat from said core by the circulation of helium into and out of said vessel to maintain the core temperature between about 700° C. and 1000° C. and to generate power from said heated helium exterior of said vessel,said a plurality of initial fissile sections of said core comprising fuel elements in the form of silicon carbide containers which contain sintered fuel bodies comprising carbide fissile and fertile nuclides, the silicon carbide containers having a thickness of at least about 1 mm, anda system for continuously withdrawing volatile fission products from said fuel elements during normal operation, the fission products being removed in a flow path separate from the helium circulation system. 2. The reactor of claim 1 wherein said a plurality of initial fissile sections comprise two spaced apart horizontal regions with each comprising a generally annular area of said fissile fuel bodies and wherein said flanking conversion sections comprise horizontal regions of fertile fuel bodies located above, between and below said two horizontal regions containing said fissile fuel bodies. 3. The reactor of claim 2 wherein said core further comprises fertile fuel bodies located in the center of and about the periphery of both of said generally annular areas of said fissile fuel bodies in their respective horizontal regions that comprise said a plurality of initial fissile sections. 4. The reactor of claim 3 wherein said horizontal regions which comprise said a plurality of initial fissile sections and said flanking conversion sections each comprise a plurality of fuel element assemblies, each assembly comprising a holder with multiple fuel elements arranged therewithin, which fuel elements contain said sintered fuel bodies and are aligned within said core to facilitate helium coolant flow vertically through said assemblies in passageways adjacent each said fuel element. 5. The reactor of claim 4 wherein said assemblies of vertically aligned fuel elements in said conversion sections and in said initial fissile section are arranged to create a plurality of juxtaposed vertical columns extending through said central core. 6. The reactor of claim 4 wherein a plurality of said fuel elements within each said holder are manifolded to a common connector to facilitate the withdrawal of volatile fission products as a composite stream from said fuel elements therewithin. 7. The reactor of claim 6 wherein said assemblies each comprise at least one of a plurality of fissile and fertile fuel elements in the form of containers formed of silicon carbide cladding that each enclose an interior fuel region in the form of a flat plate comprising at least one of sintered carbide fissile and fertile nuclides. 8. The reactor of claim 7 wherein said central core is surrounded by a plurality of blocks of BeO or Be2C reflector material to provide a surrounding reflector region that has a right circular cylindrical exterior surface. 9. The reactor of claim 8 wherein core reactivity control mechanisms in the form of vertically aligned, right circular cylindrical control drums are disposed in recesses in said reflector region to control the neutron population within said core. 10. The reactor of claim 8 wherein said reflector region is surrounded by an annular graphite outer reflector, which is in turn surrounded by an annular neutron shield containing a neutron capture material that is located in juxtaposition with a tubular core barrel that is spaced from an interior surface of said reactor vessel to provide coolant flow passageways therebetween. 11. The reactor of claim 1 wherein said sintered carbide fuel in said fuel elements occupies the interior of each said container to a packing density of about 50 to 80 volume percent in order to provide space for the accumulation of nonvolatile fission products therewithin and assure sufficient interconnected porosity for volatile fission product migration and exit therefrom. 12. The reactor of claim 11 wherein said fuel elements contain sintered near-monocarbides which comprise at least about 5% excess carbon in the immediate fuel body region to provide carbon for potential chemical reaction with fission products. 13. The reactor of claim 12 wherein said initial fissile section fuel bodies comprises UC1.05-UC1.3 with an enrichment of between about 4% and 18%. 14. A small nuclear fission waste conversion reactor designed to operate for a decade or longer without refueling, which reactor comprises:a reactor vessel,a central core within said vessel for creating heat via fission reactions in said core, which core includes one or more initial fissile sections and flanking conversion sections, which one or more initial fissile sections remain a part of the critical central core throughout reactor lifetime,a helium circulation system for extracting heat from said core by the circulation of helium into and out of said vessel to maintain the core temperature between about 700° C. and 1000° C. and to generate power from said heated helium at a location exterior of said vessel,said core including a plurality of fuel elements in the form of silicon carbide containers that enclose sintered bodies of at least one of carbide fissile and fertile nuclides, the silicon carbide containers having a thickness of at least about 1 mm, the sintered bodies each include a central hole, anda system for withdrawing volatile fission products from said plurality of fuel elements during normal operation the fission products being removed in a flow path separate from the helium circulation system via the central hole in the sintered bodies. 15. The reactor of claim 14 wherein said core further comprises additional sintered fertile fuel bodies in two initial fissile horizontal regions, which additional fertile bodies are located centrally within and about the periphery of an annular area of each fissile fuel element. 16. The reactor of claim 14 wherein the materials present within the core are selected so that a majority of the fission reactions within the core occur using neutrons that have not yet slowed to thermal energy levels. 17. The reactor of claim 14 wherein the amounts of fertile and fissile fuel in said sintered bodies within said initial core are such that, after 10 years of essentially continuous operation, the major portion of the energy being produced in the reactor results from fissioning of nuclides that were present in the initial reactor core as fertile nuclides and were subsequently converted into fissile nuclides. 18. The reactor of claim 14 wherein silicon carbide fuel element containers enclose the fissile and fertile fuel in said central core, which containers have the ability to anneal radiation-induced displacements within the temperature range of 700°-1000° C. so as to allow the central core to operate at high total fluence levels. 19. The reactor of claim 18 wherein said fuel element containers comprise woven silicon carbide material impregnated with vapor-deposited n-SiC.
	abstract	Characterizing dielectric surfaces by detecting electron tunneling. An apparatus includes an atomic force probe. A mechanical actuator is connected to the atomic force probe. A mechanical modulator is connected to the mechanical actuator. The mechanical modulator modulates the mechanical actuator and the atomic force probe at the resonant frequency of the atomic force probe. An electrical modulator is connected to the atomic force probe. A feedback sensing circuit is connected to the mechanical modulator to detect movement of the atomic force probe and provide information about the movement of the atomic force probe to the mechanical modulator allowing the mechanical modulator to modulate the atomic force probe at the resonant frequency of the atomic force probe as the resonant frequency of the atomic force probe changes. An FM detector is connected to the feedback circuit detects changes in the resonant frequency of the atomic force probe.
	summary
	abstract	A laser inertial-confinement fusion-fission energy power plant is described. The fusion-fission hybrid system uses inertial confinement fusion to produce neutrons from a fusion reaction of deuterium and tritium. The fusion neutrons drive a sub-critical blanket of fissile or fertile fuel. A coolant circulated through the fuel extracts heat from the fuel that is used to generate electricity. The inertial confinement fusion reaction can be implemented using central hot spot or fast ignition fusion, and direct or indirect drive. The fusion neutrons result in ultra-deep burn-up of the fuel in the fission blanket, thus enabling the burning of nuclear waste. Fuels include depleted uranium, natural uranium, enriched uranium, spent nuclear fuel, thorium, and weapons grade plutonium. LIFE engines can meet worldwide electricity needs in a safe and sustainable manner, while drastically shrinking the highly undesirable stockpiles of depleted uranium, spent nuclear fuel and excess weapons materials.
	claims	1. Apparatus for translation along an axis of fluid flow, the apparatus comprising:a duct configured to conduct a fluid in a first direction;a plug fixed to the duct;a loading assembly disposed within the duct and configured to move a member in the first direction into a loaded position when pressure of the fluid in the duct satisfies a loading condition;a first piston coupled to the member, the first piston within and slidably coupled to the duct, wherein the plug and the first piston define a pair of cooperating apertures that forms at least a portion of a converging-diverging passage; anda firing assembly operably coupled to the loading assembly and disposed within the duct, the firing assembly and the loading assembly being configured to store energy when the member is in the loaded position and to release stored energy and move the member out of the loaded position in a second direction opposite the first direction when the pressure of the fluid in the duct satisfies a firing condition. 2. The apparatus of claim 1, wherein the member is disposed within the duct and having an end that is configured to engage a neutron modifying material. 3. The apparatus of claim 1, wherein the converging-diverging passage is disposed along a fluid flow path such that pressure variations within the converging-diverging passage secure the first piston and the member when the pressure of the fluid in the duct satisfies the loading condition. 4. The apparatus of claim 3, wherein the pair of cooperating apertures includes a first aperture defined at least partially by the first piston and a second aperture defined at least partially by the plug, the first aperture and the second aperture defining at least a portion of a converging opening and at least a portion of a diverging opening. 5. The apparatus of claim 4, further comprising:wherein the converging opening extends between an inlet end and an inlet throat;wherein the diverging opening extends between an outlet throat and an outlet end; andwherein the inlet throat of the converging opening has an inlet throat cross-sectional area that is equalized with an outlet throat cross-sectional area of the outlet throat of the diverging opening. 6. The apparatus of claim 4, wherein the first piston includes a first body that defines the first aperture and the plug includes a second body that defines the second aperture such that the pair of cooperating apertures is spaced from peripheries of the plug and the first piston. 7. The apparatus of claim 4, further comprising:wherein the firing assembly includes a cup and a second piston, wherein the cup has a sidewall that defines an interior space; andwherein the second piston is disposed within the interior space of the cup. 8. The apparatus of claim 7, further comprising:wherein the member has an opposing second end, wherein the second piston is coupled to the opposing second end of the member, wherein the second piston includes a piston body that separates the interior space of the cup into a first region and a second region;wherein the member is positioned along the fluid flow path; andwherein the cup has an open end such that the first region is exposed to the fluid flow path. 9. The apparatus of claim 8, further comprising:wherein the cup is configured to contain a compressible fluid within the second region;wherein the cup defines an opening configured to fluidly couple the first region and a liquid coolant associated with the fluid flow path; andwherein a pressure of the compressible fluid varies with the pressure of the liquid coolant. 10. The apparatus of claim 8, further comprising:wherein the second piston is slidably coupled to the sidewall of the cup;wherein the second piston defines an orifice that places the first region in fluid communication with the second region, and wherein the orifice is configured to restrict a flow of the fluid therethrough such that release of stored energy applied by the firing assembly overcomes a suction force associated with the pressure variations within the converging-diverging passage when the pressure of the fluid in the duct satisfies a firing condition. 11. The apparatus of claim 1 further comprising a hysteresis device positioned to apply a driving force independent of release of stored energy by the firing assembly. 12. The apparatus of claim 11, further comprising:wherein the hysteresis device is configured to receive a hysteresis control signal; andwherein the hysteresis device initiates the driving force in response to receiving the hysteresis control signal. 13. The apparatus of claim 11, wherein the hysteresis device is a spring mechanism. 14. The apparatus of claim 1 further comprising an expansion device, the expansion device having a contracted state and an expanded state, and positioned to provide a resisting force in the expanded state. 15. The apparatus of claim 14, wherein the expansion device further comprises an engaging member, the engaging member maintaining the expansion device in the expanded state. 16. The apparatus of claim 15, wherein the expansion device is configured to receive an engagement control signal, wherein the engaging member maintains the expansion device in the expanded state in response to receiving the engagement control signal. 17. The apparatus of claim 15, wherein the expansion device is configured to receive a disengagement control signal, wherein the engaging member disengages and allows the expansion device to return to the contracted state in response to the disengagement control signal. 18. The apparatus of claim 14, wherein the expansion device comprises a thermal expansive material. 19. The apparatus of claim 14, wherein the expansion device further comprises a bellows. 20. The apparatus of claim 1, further comprising a locking mechanism, wherein the locking mechanism has a locked state and an unlocked state, wherein the locking mechanism in the locked state engages the loading assembly. 21. The apparatus of claim 20, wherein the locking mechanism in the locked state engaging the member inhibits movement of the member relative to the duct. 22. The apparatus of claim 20, wherein the locking mechanism is configured to receive a locking control signal, wherein the locking mechanism enters and maintains the locked state in response to receiving the locking control signal. 23. The apparatus of claim 20, wherein the locking mechanism is configured to receive an unlocking control signal, wherein the locking mechanism enters and maintains the unlocked state in response to the unlocking control signal. 24. The apparatus of claim 20, wherein the locking mechanism comprises a ferromagnetic material. 25. The apparatus of claim 1, further comprising a flow restricting device, wherein the firing assembly releases the stored energy in response to movement of the flow restricting device. 26. The apparatus of claim 25, wherein the flow restricting device moves in response to a change in temperature. 27. A nuclear reactor, comprising:a fuel assembly including a fuel assembly duct containing nuclear fuel;a pump in fluid communication with the fuel assembly duct of the fuel assembly, wherein the pump is configured to provide a coolant flow along a coolant flow path; anda control assembly including:a control assembly duct configured to conduct coolant along at least a portion of the coolant flow path;a plug fixed to the control assembly duct;a neutron modifying material coupled to a member;a first piston disposed within and slidably coupled to the control assembly duct, and coupled to the member; anda firing assembly disposed within the control assembly duct and coupled to the first piston and the member, and configured to release stored energy when the pressure of the coolant in the coolant flow path satisfies a firing condition; andwherein the release of the stored energy inserts the neutron modifying material into the nuclear fuel when the pressure of the coolant in the coolant flow path satisfiesthe firing condition; wherein the plug and the first piston define a pair of cooperating apertures that forms at least a portion of a converging-diverging passage. 28. The nuclear reactor of claim 27, wherein the converging-diverging passage is disposed along the coolant flow path such that pressure variations within the converging-diverging passage secure the neutron modifying material in a withdrawn position until the pressure of the coolant in the coolant flow path satisfies the firing condition. 29. The nuclear reactor of claim 28, wherein the pair of cooperating apertures includes a first aperture defined at least partially by the first piston and a second aperture defined at least partially by the plug, the first aperture and the second aperture defining at least a portion of a converging opening and at least a portion of a diverging opening. 30. The nuclear reactor of claim 29, wherein the converging opening extends between an inlet end and an inlet throat, wherein the diverging opening extends between an outlet throat and an outlet end, and wherein the inlet throat of the converging opening has an inlet throat cross-sectional area that is equalized with an outlet throat cross-sectional area of the outlet throat of the diverging opening. 31. The nuclear reactor of claim 29, wherein the first piston includes a first body that defines the first aperture and the plug includes a second body that defines the second aperture such that the pair of cooperating apertures is spaced from peripheries of the plug and the first piston. 32. The nuclear reactor of claim 28, wherein the firing assembly includes a cup and a second piston, wherein the cup has a sidewall that defines an interior space, and wherein the second piston is disposed within the interior space of the cup. 33. The nuclear reactor of claim 32, wherein the member has a first end and an opposing second end, wherein the neutron modifying material is coupled to the first end of the member, and wherein the second piston is coupled to the opposing second end of the member, wherein the second piston includes a piston body that separates the interior space of the cup into a first region and a second region, and wherein the cup has an open end such that the first region is exposed to the coolant flow path. 34. The nuclear reactor of claim 33, wherein the coolant is configured to store the stored energy that inserts the neutron modifying material into the nuclear fuel of the fuel assembly when the pressure of the coolant in the coolant flow path satisfies the firing condition. 35. The nuclear reactor of claim 34, wherein the second piston is slidably coupled to the sidewall of the cup, wherein the second piston defines an orifice that places the first region in fluid communication with the second region, and wherein the orifice is configured to restrict a flow of the coolant therethrough such that release of stored energy applied by the coolant overcomes a suction force associated with the pressure variations within the converging-diverging passage when the pressure of the coolant in the coolant flow path satisfies the firing condition. 36. The nuclear reactor of claim 27, wherein the control assembly further comprises a hysteresis device positioned to apply a driving force. 37. The nuclear reactor of claim 36, wherein the hysteresis device is configured to receive a hysteresis control signal, wherein the hysteresis device initiates the driving force in response to receiving the hysteresis control signal. 38. The nuclear reactor of claim 36, wherein the hysteresis device is a spring mechanism. 39. The nuclear reactor of claim 27, wherein the control assembly further comprises an expansion device, the expansion device having a contracted state and an expanded state, wherein the expansion device is positioned to provide a resisting force in the expanded state. 40. The nuclear reactor of claim 39, wherein the expansion device further comprises an engaging member, wherein the engaging member maintains the expansion device in the expanded state. 41. The nuclear reactor of claim 40, wherein the expansion device is configured to receive an engagement control signal, wherein the engaging member maintains the expansion device in the expanded state in response to receiving the engagement control signal. 42. The nuclear reactor of claim 40, wherein the expansion device is configured to receive a disengagement control signal, wherein the engaging member disengages and allows the expansion device to return to the contracted state in response to the disengagement control signal. 43. The nuclear reactor of claim 39, wherein the expansion device comprises a thermal expansive material. 44. The nuclear reactor of claim 39, wherein the expansion device further comprises a bellows. 45. The nuclear reactor of claim 27, further comprising a locking mechanism, wherein the locking mechanism has a locked state and an unlocked state, wherein the locking mechanism in the locked state engages the control assembly. 46. The nuclear reactor of claim 45, wherein the locking mechanism in the locked state engaging the control assembly inhibits movement of the firing assembly relative to the control assembly duct. 47. The nuclear reactor of claim 45, wherein the locking mechanism is configured to receive a locking control signal, wherein the locking mechanism enters and maintains the locked state in response to receiving the locking control signal. 48. The nuclear reactor of claim 45, the locking mechanism is configured to receive an unlocking control signal, wherein the locking mechanism enters and maintains the unlocked state in response to the unlocking control signal. 49. The nuclear reactor of claim 45, wherein the locking mechanism comprises a ferromagnetic material. 50. The nuclear reactor of claim 27, wherein the control assembly further comprises a flow restricting device, wherein the firing assembly releases stored energy in response to movement of the flow restricting device. 51. The nuclear reactor of claim 50, wherein the flow restricting device moves in response to a change in temperature. 52. A method of manufacturing a control assembly for a nuclear reactor, the method comprising:defining a coolant flow path within an inner volume of a duct;fixing a plug to the duct;disposing a loading assembly within the duct;slidably coupling a first piston to the duct, wherein the plug and the first piston define a pair of cooperating apertures that forms at least a portion of a converging-diverging passage;coupling a neutron modifying material to the first piston with a member;positioning the converging-diverging passage along the coolant flow path such that pressure variations within the converging-diverging passage secure the first piston, the member, and the neutron modifying material during normal operation of the nuclear reactor; andpositioning a biasing member to apply a biasing force to the member and the first piston, the biasing force releasing the first piston, the member, and the neutron modifying material when the pressure of the coolant in the duct satisfies a firing condition. 53. The method of claim 52, further comprising associating a first aperture of the pair of cooperating apertures with the first piston and a second aperture of the pair of cooperating apertures with the plug, the first aperture and the second aperture defining at least a portion of a converging opening and at least a portion of a diverging opening.
	description	The present invention relates to a scintillator panel and a radiation detector. Patent Literature 1 to Patent Literature 3 are known as technologies in this field. Patent Literature 1 discloses a scintillator panel. The scintillator panel has a metal film provided between a resin substrate and a fluorescent body layer. Patent Literature 2 discloses a radiation detection apparatus including a scintillator panel. The scintillator panel has a scintillator layer having cesium iodide as a main component. Thallium is doped into the scintillator layer. The thallium is highly concentrated near an interface of the scintillator layer with respect to a substrate. According to a concentration distribution of the thallium, an optical output is improved. Patent Literature 3 discloses a radiation detector including a fluorescent body layer. The radiation detector has a scintillator layer having cesium iodide as a main component. Thallium is doped into the scintillator layer. The thallium is highly concentrated on a substrate side in the scintillator layer. According to a concentration distribution of the thallium, adhesion between a sensor substrate and the fluorescent body layer is improved. Patent Literature 1: PCT International Publication No. WO2011/065302 Patent Literature 2: Japanese Unexamined Patent Publication No. 2008-51793 Patent Literature 3: Japanese Unexamined Patent Publication No. 2012-98110 Growth substrates for growing a scintillator layer sometimes have moisture permeability of allowing moisture to permeate thereinto. Moisture which has permeated into a growth substrate arrives at a base portion of the scintillator layer. It is known that a scintillator layer formed of cesium iodide is deliquescent. Due to moisture supplied through the growth substrate, deliquescence occurs in the base portion of the scintillator layer. As a result, characteristics of a scintillator panel deteriorate. Accordingly, in this field, it is desired that the moisture resistance of a scintillator panel having a scintillator layer formed of cesium iodide be improved. For example, a scintillator panel of Patent Literature 1 has a metal film provided between a substrate and a fluorescent body layer. The metal film hinders movement of moisture from the resin substrate to the fluorescent body layer. An object of the present invention is to provide a scintillator panel and a radiation detector, in which the moisture resistance can be improved. According to an aspect of the present invention, there is provided a scintillator panel including a substrate made of an organic material, a barrier layer formed on the substrate and including thallium iodide as a main component, and a scintillator layer formed on the barrier layer and constituted of a plurality of columnar crystals including cesium iodide with thallium added thereto as a main component. In the scintillator panel, the barrier layer is provided between the substrate and the scintillator layer. The barrier layer includes thallium iodide as a main component. The barrier layer including thallium iodide as a main component has properties of allowing scarcely any moisture to permeate thereinto. As a result, moisture which tends to move from the substrate to the scintillator layer can be blocked by the barrier layer. Since deliquescence in a base portion of the scintillator layer is curbed, deterioration in characteristics of the scintillator panel can be curbed. Accordingly, it is possible improve the moisture resistance of the scintillator panel. In the scintillator panel, the organic material may be polyethylene terephthalate. According to this constitution, it is possible to easily prepare a substrate suitable for the scintillator panel. In the scintillator panel, the organic material may be polyethylene naphthalate. According to this constitution as well, it is possible to easily prepare a substrate suitable for the scintillator panel. According to another aspect of the present invention, there is provided a radiation detector including a scintillator panel having a substrate made of an organic material, a barrier layer formed on the substrate and including thallium iodide as a main component, and a scintillator layer formed on the barrier layer and constituted of a plurality of columnar crystals including cesium iodide with thallium added thereto as a main component; and a sensor substrate including a photo-detection surface provided with a photoelectric conversion element receiving light generated in the scintillator panel. The photo-detection surface of the sensor substrate faces the scintillator layer. According to still another aspect of the present invention, there is provided a radiation detector including a substrate made of an organic material, a barrier layer formed on the substrate and including thallium iodide as a main component, and a scintillator layer formed on the barrier layer and constituted of a plurality of columnar crystals including cesium iodide with thallium added thereto as a main component. The substrate has a photo-detection surface provided with a photoelectric conversion element receiving light generated in the scintillator layer. In the radiation detector, light is generated due to radiation incident on the scintillator panel. Light is detected by the photoelectric conversion element provided on the photo-detection surface. The scintillator panel has the barrier layer including thallium iodide as a main component between the substrate and the scintillator layer. According to the barrier layer, movement of moisture from the substrate to the scintillator layer can be blocked. Accordingly, since deliquescence in the base portion of the scintillator layer is curbed, deterioration in characteristics of the scintillator panel can be curbed. As a result, in the radiation detector, deterioration in characteristics of detecting radiation is curbed. Accordingly, it is possible for the radiation detector to have improved moisture resistance. According to the present invention, there are provided a scintillator panel and a radiation detector, in which the moisture resistance can be improved. Hereinafter, with reference to the accompanying drawings, embodiments of the present invention will be described in detail. In description of the drawings, the same reference signs will be applied to the same elements, and duplicate description will be omitted. As illustrated in FIG. 1, a scintillator panel 1 according to a first embodiment has a substrate 2, a barrier layer 3, a scintillator layer 4, and a protective film 6. The scintillator panel 1 is combined with a photoelectric conversion element (not illustrated) and is used as a radiation image sensor. The substrate 2, the barrier layer 3, and the scintillator layer 4 are laminated in this order in a thickness direction thereof and constitute a laminated body 7. Specifically, the barrier layer 3 is formed on the substrate 2. The scintillator layer 4 is formed on the barrier layer 3. The substrate 2 and the scintillator layer 4 do not directly come into contact with each other. The laminated body 7 has a laminated body front surface 7a, a laminated body rear surface 7b, and a laminated body side surface 7c. The laminated body 7 is covered with the protective film 6. Specifically, each of the laminated body front surface 7a, the laminated body rear surface 7b, and the laminated body side surface 7c is covered with the protective film 6. That is, each of the laminated body front surface 7a, the laminated body rear surface 7b, and the laminated body side surface 7c is not directly exposed to the atmosphere. The substrate 2 constitutes a base body of the scintillator panel 1. The substrate 2 exhibits a rectangular shape, a polygonal shape, or a circular shape in a plan view. The thickness of the substrate 2 is within a range of 10 micrometers to 5,000 micrometers. As an example, the thickness of the substrate 2 is 100 micrometers. The substrate 2 has a substrate front surface 2a, a substrate rear surface 2b, and a substrate side surface 2c. The substrate rear surface 2b constitutes the laminated body rear surface 7b. The substrate side surface 2c constitutes a portion of the laminated body side surface 7c. The substrate 2 is made of an organic material. Examples of the organic material include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), and polyimide (PI). The barrier layer 3 hinders movement of moisture from the substrate 2 to the scintillator layer 4. The barrier layer 3 is formed on the substrate front surface 2a. The thickness of the barrier layer 3 is within a range of 0.001 micrometers to 1.0 micrometer. As an example, the thickness of the barrier layer 3 is 0.06 micrometers (600 angstroms). The barrier layer 3 has a barrier layer front surface 3a, a barrier layer rear surface 3b, and a barrier layer side surface 3c. The barrier layer side surface 3c constitutes a portion of the laminated body side surface 7c. The barrier layer 3 includes thallium iodide (TlI) as a main component. For example, the TlI content of the barrier layer 3 may be within a range of 90% to 100%. When the TlI content in the barrier layer 3 is 90% or more, it may be stated that the barrier layer 3 has TlI as a main component. For example, the barrier layer 3 may be formed by a two-source vapor deposition method. Specifically, a first vapor deposition source containing cesium iodide (CsI) and a second vapor deposition source containing thallium iodide (TlI) are utilized. The barrier layer 3 is formed by performing vapor deposition of TlI on a substrate prior to CsI. As an example, the thickness of the barrier layer 3 is approximately 600 angstroms. The thickness of the barrier layer 3 can be measured by causing a scintillator layer and a substrate to peel off using a strong adhesive tape or the like and analyzing a substrate interface using an X-ray fluorescence analysis (XRF) apparatus. Examples of X-ray fluorescence analysis apparatuses can include ZSX Primus of RIGAKU Corporation. The scintillator layer 4 receives radiation and generates light corresponding to the radiation. The scintillator layer 4 includes cesium iodide (fluorescent body material) as a main component. Moreover, the scintillator layer 4 includes thallium as a dopant (CsI:Tl). For example, the CsI content of the scintillator layer 4 may be within a range of 90% to 100%. When the CsI content of the scintillator layer 4 is 90% or more, it may be stated that the scintillator layer 4 has CsI as a main component. The scintillator layer 4 is constituted of a plurality of columnar crystals. Each of the columnar crystals exhibits a light guiding effect. Accordingly, the scintillator layer 4 is suitable for high-resolution imaging. For example, the scintillator layer 4 may be formed by a vapor deposition method. The thickness of the scintillator layer 4 is within a range of 10 micrometers to 3,000 micrometers. As an example, the thickness of the scintillator layer 4 is 600 micrometers. The scintillator layer 4 has a scintillator layer front surface 4a, a scintillator layer rear surface 4b, and a scintillator layer side surface 4c. The scintillator layer front surface 4a constitutes the laminated body front surface 7a. The scintillator layer side surface 4c constitutes a portion of the laminated body side surface 7c described above. The scintillator layer 4 includes a plurality of columnar crystals extending in the thickness direction of the scintillator layer 4. Base portions of the plurality of columnar crystals constitute the scintillator layer rear surface 4b. The base portions come into contact with the barrier layer front surface 3a of the barrier layer 3. Tip portions of the plurality of columnar crystals constitute the scintillator layer front surface 4a. The columnar crystals formed in an outer circumferential portion of the scintillator layer 4 constitute the scintillator layer side surface 4c. The laminated body side surface 7c includes the substrate side surface 2c, the barrier layer side surface 3c, and the scintillator layer side surface 4c. The substrate side surface 2c, the barrier layer side surface 3c, and the scintillator layer side surface 4c are flush with each other. The expression “flush with each other” denotes that when the substrate side surface 2c, the barrier layer side surface 3c, and the scintillator layer side surface 4c are viewed in a macroscopic manner, each of the surfaces is included in the same virtual plane. There may be cases where the substrate side surface 2c and the scintillator layer side surface 4c have minute uneven structures such as an undercut, a coarse surface, or burrs when viewed in a microscopic manner. However, when they are defined to be “flush with each other”, the uneven structures are disregarded. The protective film 6 covers the laminated body 7. As a result, the protective film 6 protects the laminated body 7 from moisture. The protective film 6 covers the substrate rear surface 2b, the substrate side surface 2c, the barrier layer side surface 3c, and the scintillator layer side surface 4c, and the scintillator layer front surface 4a. The thickness of the protective film 6 may be substantially the same at all places where it is formed. In addition, the thickness of the protective film 6 may vary at every place. In the protective film 6, for example, a film portion formed on the scintillator layer front surface 4a is thicker than film portions formed on the substrate rear surface 2b, the substrate side surface 2c, the barrier layer side surface 3c, and the scintillator layer side surface 4c. The protective film 6 may include polyparaxylylene as a main component. The protective film 6 may be formed by a chemical vapor deposition (CVD) method, for example. In the scintillator panel 1, the barrier layer 3 is provided between the substrate 2 and the scintillator layer 4. The barrier layer 3 includes thallium iodide as a main component. The barrier layer 3 has properties of allowing scarcely any moisture to permeate thereinto. Accordingly, moisture which tends to move from the substrate 2 to the scintillator layer 4 can be blocked by the barrier layer 3. As a result, deliquescence in the base portion of the scintillator layer 4 is curbed. Accordingly, deterioration in characteristics of the scintillator panel 1 can be curbed. In the scintillator panel 1, the organic material is polyethylene terephthalate. According to this constitution, the substrate 2 suitable for the scintillator panel 1 can be easily prepared. A substrate suitable for the scintillator panel 1 is a substrate which can be evaluated as being favorable when evaluated based on heat resistance at the time of forming a scintillator layer, handleability at the time of forming a scintillator panel, optical characteristics (reflectivity or absorptivity) with respect to scintillation light, radiation transmission properties, availability, price, and the like. In the scintillator panel 1, the organic material is polyethylene naphthalate, polyimide, or polyetheretherketone. According to this constitution as well, the substrate 2 suitable for the scintillator panel 1 can be easily prepared. A radiation detector according to a second embodiment will be described. Actually, a region (side) for achieving electrical conduction is provided on a sensor panel 11. However, it is not illustrated in each of the drawings for the sake of convenience. As illustrated in FIG. 2, a radiation detector 10 has the sensor panel 11 (sensor substrate), a barrier layer 3A, a scintillator layer 4A, and a sealing portion 12. Radiation received from a sealing plate 14 is incident on the scintillator layer 4A. The scintillator layer 4A generates light corresponding to the radiation. The light passes through the barrier layer 3A and is incident on the sensor panel 11. The sensor panel 11 generates an electrical signal in response to the incident light. The electrical signal is output through a predetermined electric circuit. According to the electrical signal, a radiation image is obtained. The sensor panel 11 has a panel front surface 11a, a panel rear surface 11b, and a panel side surface 11c. The sensor panel 11 is a CCD sensor, a CMOS sensor, or a TFT panel having a photoelectric conversion element 16. The sensor panel 11 includes a substrate made of an organic material. A plurality of photoelectric conversion elements 16 are disposed on the panel front surface 11a in a two-dimensional manner. A region on the panel front surface 11a on which a plurality of photoelectric conversion elements 16 are disposed is a photo-detection region S1 (photo-detection surface). In addition to the photo-detection region S1, the panel front surface 11a includes a surrounding region S2 surrounding the photo-detection region S1. The barrier layer 3A is formed on the panel front surface 11a. The barrier layer 3A has the barrier layer front surface 3a, the barrier layer rear surface 3b, and the barrier layer side surface 3c. More specifically, the barrier layer 3A is formed on the panel front surface 11a such that the photo-detection region S1 is covered. The barrier layer front surface 3a faces the panel front surface 11a. When the barrier layer 3A is viewed in a plan view, the barrier layer 3A is smaller than the sensor panel 11. Accordingly, the barrier layer side surface 3c is not flush with the panel side surface 11c. In the barrier layer 3A, excluding the foregoing constitution, the constitution is otherwise similar to that of the barrier layer 3 in the first embodiment. For example, a material and the like constituting the barrier layer 3A are the same as those of the barrier layer 3 according to the first embodiment. The scintillator layer 4A is formed on the barrier layer 3A. More specifically, the scintillator layer 4A is formed on the barrier layer rear surface 3b. That is, similar to the barrier layer 3A, the scintillator layer 4A is also formed such that the photo-detection region S1 is covered with the barrier layer 3A therebetween. According to this constitution, light from the scintillator layer 4A can be reliably captured by the photoelectric conversion elements 16. In addition, the scintillator layer side surface 4c is not flush with the panel side surface 11c. The scintillator layer 4A exhibits a truncated pyramid shape. The scintillator layer side surface 4c is tilted with respect to the thickness direction of the scintillator layer 4A. In other words, the scintillator layer side surface 4c is a slope (inclination). Specifically, when the scintillator layer 4A is viewed in a cross-sectional view in a direction orthogonal to the thickness direction, a cross section exhibits a trapezoidal shape. One side on the scintillator layer front surface 4a side is longer than one side on the scintillator layer rear surface 4b side. The sealing portion 12 covers a portion of the panel front surface 11a of the sensor panel 11, the barrier layer 3A, and the scintillator layer 4A. The sealing portion 12 is fixed to the surrounding region S2 on the panel front surface 11a. The sealing portion 12 air-tightly maintains an internal space formed by the sealing portion 12 and the sensor panel 11. Due to this constitution, the scintillator layer 4A is protected from moisture. The sealing portion 12 has a sealing frame 13 and the sealing plate 14. The sealing frame 13 has a frame front surface 13a, a frame rear surface 13b, and a frame wall portion 13c. The frame wall portion 13c joins the frame front surface 13a and the frame rear surface 13b to each other. The height of the frame wall portion 13c (that is, the length from the frame front surface 13a to the frame rear surface 13b) is higher than the height from the panel front surface 11a to the scintillator layer rear surface 4b. A gap is formed between the scintillator layer rear surface 4b and the sealing plate 14. The sealing frame 13 may be constituted of a resin material, a metal material, or a ceramic material, for example. The sealing frame 13 may be solid or hollow. The frame front surface 13a and a plate rear surface 14b, and the frame rear surface 13b and the panel front surface 11a may be joined to each other using an adhesive. The sealing plate 14 is a plate material having a rectangular shape in a plan view. The sealing plate 14 has a plate front surface 14a, the plate rear surface 14b, and a plate side surface 14c. The plate rear surface 14b is fixed to the frame front surface 13a. The plate side surface 14c may be flush with an outer surface of the frame wall portion 13c. The sealing plate 14 may be constituted of a glass material, a metal material, a carbon material, or a barrier film, for example. Examples of a metal material include aluminum. Examples of a carbon material include carbon fiber reinforced plastic (CFRP). Examples of a barrier film include a laminated body of an organic material layer (PET and/or PEN) and an inorganic material layer (SiN). In the radiation detector 10, light is generated due to radiation incident on the scintillator layer 4A, and the light is detected by the photoelectric conversion elements 16 provided in the photo-detection region S1. The radiation detector 10 has the barrier layer 3A including thallium iodide as a main component between the sensor panel 11 and the scintillator layer 4A. The barrier layer 3A blocks movement of moisture from the sensor panel 11 to the scintillator layer 4A. Accordingly, deliquescence in the base portion of the scintillator layer 4A is curbed. As a result, deterioration in characteristics of the radiation detector 10 can be curbed. Hereinabove, embodiments of the present invention have been described. However, the present invention is not limited to the foregoing embodiments and can be performed in various forms. Modification examples 1 to 14 are modification examples of the first embodiment. In addition, Modification examples 15 to 20 are modification examples of the second embodiment. FIG. 3A illustrates a scintillator panel 1A according to Modification Example 1. The scintillator panel 1A may further have another layer, in addition to the substrate 2, the barrier layer 3, and the scintillator layer 4. The scintillator panel 1A has a functional layer 8 as another layer thereof. In the functional layer 8, a functional layer front surface 8a faces the substrate rear surface 2b. The functional layer 8 includes an inorganic material as a main component. The functional layer 8 may be a coating layer formed of a metal foil, a metal sheet, or an inorganic material, for example. A laminated body 7A including the functional layer 8 is covered with the protective film 6. That is, the protective film 6 covers a functional layer rear surface 8b and a functional layer side surface 8c of the functional layer 8, the substrate side surface 2c, the barrier layer side surface 3c, the scintillator layer side surface 4c, and the scintillator layer front surface 4a. According to the scintillator panel 1A, the scintillator layer 4 can be protected from moisture infiltrating into the substrate 2 by the barrier layer 3 and the functional layer 8. FIG. 3B illustrates a scintillator panel 1B according to Modification Example 2. The scintillator panel 1B may have a functional layer 8A having a constitution different from that in Modification example 1. The functional layer 8A is also formed on the substrate side surface 2c, in addition to the substrate rear surface 2b. That is, the functional layer 8A has a first part formed on the substrate rear surface 2b, and a second part formed on the substrate side surface 2c. The first part has the functional layer front surface 8a and the functional layer rear surface 8b. The functional layer front surface 8a faces the substrate rear surface 2b. That is, the entire front surface of the substrate 2 is covered with the barrier layer 3 and the functional layer 8A. The functional layer 8A includes an inorganic material as a main component. The functional layer 8A may be a coating layer formed of an inorganic material, for example. A laminated body 7B including the functional layer 8A is covered with the protective film 6. That is, the protective film 6 covers the first part of the functional layer 8A, the second part of the functional layer 8A, the barrier layer side surface 3c, the scintillator layer side surface 4c, and the scintillator layer front surface 4a. According to the scintillator panel 1B, the scintillator layer 4 can be protected from moisture infiltrating into the substrate 2 by the barrier layer 3 and the functional layer 8A. FIG. 4A illustrates a scintillator panel 1C according to Modification Example 3. The scintillator panel 1C may have a functional layer 8B which differs from that in Modification example 1. The functional layer 8B is formed on the protective film 6. Specifically, the laminated body 7 including the substrate 2, the barrier layer 3, and the scintillator layer 4 is covered with the protective film 6. That is, the protective film 6 covers the substrate rear surface 2b. The functional layer 8B is formed on a part covering the substrate rear surface 2b. Accordingly, the scintillator panel 1C has a laminated structure in which the functional layer 8B, the protective film 6, the substrate 2, the barrier layer 3, and the scintillator layer 4 are laminated in this order in the thickness direction. The functional layer 8B includes an inorganic material as a main component. The functional layer 8B may be a coating layer formed of a metal foil, a metal sheet, or an inorganic material, for example. According to the scintillator panel 1C, the scintillator layer 4 can be protected from moisture infiltrating into the substrate 2 by the barrier layer 3 and the functional layer 8B. FIG. 4B illustrates a scintillator panel 1D according to Modification Example 4. The scintillator panel 1D according to Modification Example 4 may have a functional layer 8C which differs from that in Modification example 1. The functional layer 8C is formed on the protective film 6. The functional layer 8C covers at least a portion of the laminated body 7. Specifically, the laminated body 7 including the substrate 2, the barrier layer 3, and the scintillator layer 4 is covered with the protective film 6. The protective film 6 has a part covering the substrate rear surface 2b and a part covering the substrate side surface 2c. The functional layer 8C is formed on each of a part covering the substrate rear surface 2b and a part covering the substrate side surface 2c. Accordingly, the scintillator panel 1D has a laminated structure in which the functional layer 8C, the protective film 6, the substrate 2, the barrier layer 3, and the scintillator layer 4 are laminated in this order in the thickness direction. The scintillator panel 1D has a laminated structure in which the functional layer 8C, the protective film 6, the substrate 2, the barrier layer 3, and the scintillator layer 4 are laminated in this order in a direction intersecting the thickness direction. The functional layer 8C includes an inorganic material as a main component. The functional layer 8C may be a coating layer formed of a metal foil, a metal sheet, or an inorganic material, for example. According to the scintillator panel 1D, the scintillator layer 4 can be protected from moisture infiltrating into the substrate 2 by the barrier layer 3 and the functional layer 8C. The scintillator panel 1 according to the first embodiment can be obtained by forming a panel base body having the barrier layer 3 and the scintillator layer 4 formed therein on one large substrate 2 and by cutting the panel base body. Accordingly, machining marks corresponding to a form of cutting are generated in the panel side surface 11c of the scintillator panel 1 sometimes. For example, a laser beam may be utilized in cutting of the panel base body. FIG. 5A illustrates a scintillator panel 1E according to Modification Example 5. The scintillator panel 1E may have a melted region 5 formed on the laminated body side surface 7c. The melted region 5 is a part realized by portions of the substrate 2, the barrier layer 3, and the scintillator layer 4 which have been melted and resolidified due to a laser beam. That is, the melted region 5 is formed on the entire surface of each of the substrate side surface 2c, the barrier layer side surface 3c, and the scintillator layer side surface 4c. According to the scintillator panel 1E, cutting using a laser beam can be performed. Such machining marks are formed through steps as described below. First, the laminated body 7 is formed. Next, the laminated body 7 is irradiated with a laser beam from the scintillator layer 4 side. A laser beam performs cutting in the order of the scintillator layer 4, the barrier layer 3, and the substrate 2. Cleavability of the substrate 2 is lower than cleavability of the scintillator layer 4 and the barrier layer 3 made of a plurality of columnar crystals. Accordingly, irradiation of a laser beam continues until the laser beam arrives at the substrate rear surface 2b. In other words, irradiation of a laser beam continues from the scintillator layer front surface 4a to the substrate rear surface 2b. As a result, the melted region 5 is formed over the entire surface of the laminated body side surface 7c which is a cut surface. FIG. 5B illustrates a scintillator panel 1F according to Modification Example 6. The scintillator panel 1F may have a melted region 5A formed in a portion of the laminated body side surface 7c. The melted region 5A is formed on the entire surface of the substrate side surface 2c, on the entire surface of the barrier layer side surface 3c, and in a portion on the scintillator layer side surface 4c. Specifically, the melted region 5A is formed in a part on the scintillator layer side surface 4c connected to the barrier layer side surface 3c. Such machining marks are formed through steps as described below. First, the laminated body 7 is formed. Next, the laminated body 7 is irradiated with a laser beam from the substrate 2 side. A laser beam performs cutting in the order of the substrate 2, the barrier layer 3, and the scintillator layer 4. The scintillator layer 4 is aggregation of columnar crystals. Accordingly, the scintillator layer 4 has high cleavability. When a groove or a crack is generated in the base portion of the scintillator layer 4, the scintillator layer 4 is cleaved with the crack as a starting point. Accordingly, there is no need to continue irradiation of a laser beam from the substrate rear surface 2b to the scintillator layer front surface 4a. When a laser beam slightly arrives at the scintillator layer side surface 4c from the substrate rear surface 2b, irradiation is stopped. Then, the scintillator layer 4 is cleaved with a groove or a crack formed in the scintillator layer 4 as a starting point. According to this cutting method, irradiation of a laser beam with respect to the scintillator layer 4 can be kept at the minimum. Accordingly, compared to the cutting method in Modification example 5, damage to the scintillator layer 4 can be reduced. FIG. 5C illustrates a scintillator panel 1G according to Modification Example 7. The scintillator panel 1G may have a melted region 5B formed in a portion of the laminated body side surface 7c. The melted region 5B has a melted portion 5a formed on the substrate side surface 2c, and a melted portion 5b formed in a portion on the scintillator layer side surface 4c. Specifically, the melted portion 5b is formed in a part on the scintillator layer side surface 4c on the scintillator layer front surface 4a side. In other words, the melted region 5B is not formed in the base portion of the scintillator layer 4. A melted region connected to the melted portion 5a may be formed on the barrier layer side surface 3c. Such machining marks are formed through steps as described below. First, the laminated body 7 is formed. Next, the laminated body 7 is irradiated with a laser beam from the substrate 2 side. Then, when a laser beam arrives at the substrate front surface 2a, irradiation is stopped. Through this step, the melted portion 5a on the substrate side surface 2c is formed. Next, irradiation of a laser beam is performed from the scintillator layer 4 side. Then, when the laser beam arrives at a predetermined depth from the scintillator layer front surface 4a, irradiation is stopped. That is, irradiation of a laser beam is not continuously performed from the scintillator layer front surface 4a to the scintillator layer rear surface 4b. In this stage, integrity of the laminated body 7 is maintained by the base portion of the scintillator layer 4 and the barrier layer 3. Next, the scintillator layer 4 is cleaved with a groove and/or a crack provided in the scintillator layer 4 as a starting point. According to this cutting method, irradiation of a laser beam with respect to the scintillator layer 4 can be kept at the minimum. Accordingly, compared to the cutting method in Modification example 5, damage to the scintillator layer 4 can be reduced. FIG. 6A illustrates a scintillator panel 1H according to Modification Example 8. The scintillator panel 1H has a protective sheet 6A, in place of the protective film 6. That is, the scintillator panel 1H has the laminated body 7 and the protective sheet 6A. The protective sheet 6A is constituted by bonding two sheet members 6a and 6b to each other. Specifically, the sheet member 6a is disposed such that it faces the scintillator layer front surface 4a, and the sheet member 6b is disposed such that it faces the substrate rear surface 2b. A gap may be provided between the sheet member 6a and the scintillator layer front surface 4a, and between the sheet member 6b and the substrate rear surface 2b. The sheet member 6a and the scintillator layer front surface 4a may come into contact with each other. The sheet member 6b and the substrate rear surface 2b may come into contact with each other. A surrounding portion of the sheet member 6a overlaps the surrounding portion of the sheet member 6b such that they adhere to each other. According to this constitution, an internal region containing the laminated body 7 can be air-tightly maintained. Accordingly, the scintillator layer 4 can be protected from moisture. FIG. 6B illustrates a scintillator panel 1K according to Modification Example 9. The scintillator panel 1K may have a bag-shaped protective sheet 6B, in place of the protective film 6. That is, the scintillator panel 1K has the laminated body 7 and the protective sheet 6B. The protective sheet 6B has an opening. The protective sheet 6B receives the laminated body 7 through the opening. After the laminated body 7 is received, the opening is closed and is fixed using an adhesive or the like. According to this constitution as well, an internal region containing the laminated body 7 can be air-tightly maintained. Accordingly, the scintillator layer 4 can be protected from moisture. FIG. 7A illustrates a radiation detector 10A according to Modification Example 10. The radiation detector 10A has the laminated body 7 of the scintillator panel 1 according to the first embodiment, the sensor panel 11, and the sealing portion 12. The sensor panel 11 has a constitution substantially similar to that of the sensor panel 11 of the radiation detector 10 according to the second embodiment. The sealing portion 12 has a constitution substantially similar to that of the sealing portion 12 of the radiation detector 10 according to the second embodiment. In the radiation detector 10A according to Modification Example 10, the height of the frame wall portion 13c of the sealing frame 13 is higher than the height from the panel front surface 11a to the substrate rear surface 2b. The sealing frame 13 may be constituted of a resin material, a metal material, or a ceramic material, for example. When the sealing frame 13 is constituted of a metal material or a ceramic material, an adhesion layer (not illustrated) is formed between the frame front surface 13a and the sealing plate 14. In addition, an adhesion layer (not illustrated) is formed between the frame rear surface 13b and the panel front surface 11a. The sealing plate 14 may be constituted of a glass material, a metal material, a carbon material, or a barrier film, for example. Examples of a metal material include aluminum. Examples of a carbon material include CFRP. Examples of a barrier film include a laminated body of an organic material layer (PET or PEN) and an inorganic material layer (SiN). In the radiation detector 10A, the scintillator layer 4 can be protected from moisture by the sensor panel 11 and the sealing portion 12. FIG. 7B illustrates a radiation detector 10B according to Modification Example 11. The radiation detector 10B has a sealing portion 12A which differs from the radiation detector 10A of Modification example 10. The constitutions of the laminated body 7 and the sensor panel 11 are otherwise similar to those in Modification example 10. The sealing portion 12A has the sealing plate 14 and a sealing frame 13A. The sealing frame 13A further has an inner sealing frame 17 and an outer sealing frame 18. The sealing frame 13 has a dual structure. The inner sealing frame 17 may be constituted of a resin material, for example. The outer sealing frame 18 may be constituted of an inorganic solid material such as a coating layer formed of an inorganic material or a glass rod, for example. In the radiation detector 10B, the scintillator layer 4 can be preferably protected from moisture by the sensor panel 11 and the sealing portion 12A. FIG. 8A illustrates a radiation detector 10C according to Modification Example 12. The radiation detector 10C according to Modification Example 12 has a laminated body 7C having a constitution different from that of the laminated body 7 of the sensor panel 11 according to the first embodiment. The laminated body 7C has a substrate 2A, the barrier layer 3A, and the scintillator layer 4A. The single body constitution of the barrier layer 3A according to Modification Example 12 is similar to that of the barrier layer 3A according to the second embodiment. The single body constitution of the scintillator layer 4A according to Modification Example 12 is similar to that of the scintillator layer 4A according to the second embodiment. Accordingly, the scintillator layer side surface 4c is tilted with respect to the thickness direction. The laminated body 7C differs from the laminated body 7 according to the first embodiment in that the substrate side surface 2c and the barrier layer side surface 3c are not flush with each other and the substrate side surface 2c and the scintillator layer side surface 4c are not flush with each other. When the laminated body 7C is viewed in the thickness direction in a plan view, the substrate 2A is larger than the barrier layer 3A and the scintillator layer 4A. Accordingly, the substrate front surface 2a has an exposed region S3 exposed from the barrier layer 3A and the scintillator layer 4A. The laminated body 7C is attached to the sensor panel 11 such that the scintillator layer front surface 4a faces the panel front surface 11a. According to this constitution, the exposed region S3 in the substrate front surface 2a faces the surrounding region S2 of the panel front surface 11a. The substrate front surface 2a is separated from the panel front surface 11a as much as the heights of the scintillator layer 4A and the barrier layer 3A. Here, the sealing frame 13 is sandwiched between the substrate front surface 2a and the panel front surface 11a. The sealing frame 13 and the substrate 2A are fixed to each other through adhesion. Similarly, the sealing frame 13 and the sensor panel 11 are fixed to each other through adhesion. According to this constitution, the substrate 2A can exhibit a function as a growth substrate for the barrier layer 3A and the scintillator layer 4A, and a function as a sealing plate in the radiation detector 10C. Accordingly, the number of components constituting the radiation detector 10C can be reduced. FIG. 8B illustrates a radiation detector 10D according to Modification Example 13. The radiation detector 10D has the sealing frame 13A which differs from the radiation detector 10C of Modification example 12. The constitutions of the laminated body 7C and the sensor panel 11 are similar to those in Modification example 12. The sealing frame 13A has a constitution similar to that of the sealing frame 13A according to Modification Example 11. Accordingly, the sealing frame 13A has the inner sealing frame 17 and the outer sealing frame 18. In the radiation detector 10D, the scintillator layer 4A can be protected from moisture by the substrate 2A, the sensor panel 11, and the sealing frame 13A. FIG. 9A illustrates a radiation detector 10E according to Modification Example 14. The radiation detector 10E has the laminated body 7, a protective film 6C, and the sensor panel 11. The radiation detector 10E further has a fiber optical plate (which will hereinafter be referred to as “an FOP 9”). The FOP 9 is disposed between the laminated body 7 and the sensor panel 11. The laminated body 7 is joined to the sensor panel 11 with the FOP 9 therebetween. Specifically, the FOP 9 is disposed between the scintillator layer 4 and the sensor panel 11. The FOP 9 has an FOP front surface 9a, an FOP rear surface 9b, and an FOP side surface 9c. The FOP rear surface 9b comes into contact with the scintillator layer front surface 4a. The FOP front surface 9a comes into contact with the panel front surface 11a. The FOP side surface 9c is flush with the laminated body side surface 7c. The protective film 6C covers the substrate rear surface 2b, the substrate side surface 2c, the barrier layer side surface 3c, the scintillator layer side surface 4c, and the FOP side surface 9c. Accordingly, the protective film 6C is not formed between the scintillator layer 4 and the FOP 9, and between the FOP 9 and the sensor panel 11. In the radiation detector 10E, the scintillator layer 4 is protected from moisture. In addition, in the radiation detector 10E, the scintillator layer 4 can be preferably optically connected to the sensor panel 11 using the FOP 9. Then, in the radiation detector 10E, there is no protective film 6C between the scintillator layer 4 and the FOP 9, and between the FOP 9 and the sensor panel 11. As a result, in the radiation detector 10E, deterioration in resolution can be curbed. As a radiation detector 10S illustrated in FIG. 9B, the protective film 6C may cover an outer circumferential surface of the laminated body 7. The protective film 6C may be formed between the laminated body 7 and the FOP 9. FIG. 10A illustrates a radiation detector 10F according to Modification Example 15. The radiation detector 10F has the sealing portion 12A which differs from that in the radiation detector 10 according to the second embodiment. The constitutions of the barrier layer 3A, the scintillator layer 4A, and the sensor panel 11 are similar to those in the radiation detector 10 according to the second embodiment. The sealing portion 12A has a constitution similar to that of the sealing portion 12A according to Modification Example 11. The sealing portion 12A has the sealing plate 14 and the sealing frame 13A. The sealing frame 13A further has the inner sealing frame 17 and the outer sealing frame 18. In the radiation detector 10F, the scintillator layer 4A can be preferably protected from moisture. FIG. 10B illustrates a radiation detector 10G according to Modification Example 16. The radiation detector 10G differs from the radiation detector 10 according to the second embodiment in having no sealing portion 12 and having a protective film 6D in place of the sealing portion 12. The constitutions of the barrier layer 3A, the scintillator layer 4A, and the sensor panel 11 are similar to those in the radiation detector 10 according to the second embodiment. The protective film 6D covers the panel front surface 11a, the barrier layer side surface 3c, the scintillator layer side surface 4c, and the scintillator layer rear surface 4b. In the radiation detector 10G, the scintillator layer 4A can be protected from moisture. The protective film 6D is made of a material similar to that of the protective film 6. FIG. 10C illustrates a radiation detector 10H according to Modification Example 17. The radiation detector 10H is realized by adding a sealing frame 13B to the radiation detector 10G according to Modification Example 16. Accordingly, the scintillator layer 4A, the barrier layer 3A, the sensor panel 11, and the protective film 6D are similar to those in the radiation detector 10G according to Modification Example 16. The sealing frame 13B blocks a joining portion between the sensor panel 11 and the protective film 6D. Accordingly, when viewed in the thickness direction in a plan view, the sealing frame 13B is formed along an outer edge of the protective film 6D. The sealing frame 13B may be constituted of a UV curable resin, for example. According to this constitution, invasion of moisture through the joining portion between the sensor panel 11 and the protective film 6D is curbed. Accordingly, the moisture resistance of the radiation detector 10H can be further enhanced. FIG. 11A illustrates a radiation detector 10K according to Modification Example 18. The radiation detector 10K has no sealing portion 12 of the radiation detector 10 according to the second embodiment. The radiation detector 10K has a sealing sheet 12B, in place of the sealing portion 12. The constitutions of the barrier layer 3A, the scintillator layer 4A, and the sensor panel 11 are similar to those in the radiation detector 10 according to the second embodiment. The sealing sheet 12B exhibits a rectangular shape, a polygonal shape, or a circular shape in a plan view in the thickness direction. The sealing sheet 12B may be constituted of a metal foil, a metal sheet such as an aluminum sheet, or a barrier film, for example. The sealing sheet 12B covers the scintillator layer 4A and the barrier layer 3A. Specifically, it covers the scintillator layer rear surface 4b, the scintillator layer side surface 4c, the barrier layer side surface 3c, and a portion of the panel front surface 11a. In a plan view, the sealing sheet 12B is larger than the scintillator layer 4A and the barrier layer 3A. An outer circumferential edge 12a of the sealing sheet 12B adheres to the panel front surface 11a using an adhesive 15. Accordingly, the sealing sheet 12B and the sensor panel 11 form an air-tight region containing the scintillator layer 4A and the barrier layer 3A. Accordingly, in the radiation detector 10K, the scintillator layer 4A can be protected from moisture. The adhesive 15 may include filler materials. The particle sizes of the filler materials are smaller than the thickness of the adhesion layer. In the radiation detector 10K, the scintillator layer 4A can be preferably protected from moisture. FIG. 11B illustrates a radiation detector 10L according to Modification Example 19. The radiation detector 10L has a sealing frame 12C having a constitution different from that of the sealing sheet 12B according to Modification Example 18. The sealing frame 12C exhibits a box shape. The sealing frame 12C has an opening on a bottom surface. The sealing sheet 12B according to Modification Example 18 has flexibility. On the other hand, the sealing frame 12C according to Modification Example 19 maintains a predetermined shape and is hard. Accordingly, the sealing frame 12C may be constituted of a glass material, a metal material, or a carbon material, for example. The bottom surface of the sealing frame 12C adheres to the panel front surface 11a using the adhesive 15. According to this constitution, the scintillator layer 4A is disposed in an air-tight region formed by the sealing frame 12C and the sensor panel 11. As a result, the scintillator layer 4A can be protected from moisture. In addition, since the sealing frame 12C is hard, the scintillator layer 4A can be protected mechanically. FIG. 12 illustrates a radiation detector 10M according to Modification Example 20. The radiation detector 10M has a barrier layer 3B and a scintillator layer 4B which differ from those in the radiation detector 10 according to the second embodiment. The barrier layer 3B has the barrier layer front surface 3a, the barrier layer rear surface 3b, and the barrier layer side surface 3c. The scintillator layer 4B has the scintillator layer front surface 4a, the scintillator layer rear surface 4b, and the scintillator layer side surface 4c. The single body constitution of the sensor panel 11 is similar to that in the radiation detector 10 according to the second embodiment. The scintillator layer 4B is formed on one side surface of the sensor panel 11 such that it protrudes from the photo-detection region S1. Specifically, first, the barrier layer 3B is formed on the photo-detection region S1, the panel side surface 11c on one side, and a peripheral region S2a between the photo-detection region S1 and the panel side surface 11c on one side. Then, the scintillator layer 4B is formed on the entire surface of the barrier layer 3B such that the barrier layer 3B is covered. The radiation detector 10M having this constitution can be preferably used as a radiation detector for mammography. In such application of the radiation detector 10M, the scintillator layer 4B is disposed such that a side formed to protrude from the photo-detection region S1 is positioned on the breast-wall side of an examinee. In the experimental example, effects of improvement in moisture resistance exhibited by the barrier layer, have been confirmed. The moisture resistance stated in the present experimental example denotes a relationship between a time being exposed to an environment having predetermined humidity and a degree of change in resolution (CTF) indicated by the scintillator panel. That is, high moisture resistance denotes that the degree of deterioration in resolution indicated by the scintillator panel is low even when it is exposed to a humidity environment for a long time. On the contrary, low moisture resistance denotes that the degree of deterioration in resolution indicated by the scintillator panel is high when it is exposed to a humidity environment for a long time. In the experimental example, first, three test bodies (scintillator panels) were prepared. Each of the test bodies had a scintillator layer and a substrate. Each of the scintillator layers included CsI as a main component, and the thickness thereof was 600 micrometers. Then, first and second test bodies had a barrier layer including TlI as a main component between the substrate and the scintillator layer. On the other hand, a third test body had no barrier layer. The third test body was a comparative example in which a scintillator layer was formed directly on a substrate. The substrate of the first test body was an organic substrate including an organic material as a main component. The first test body corresponds to the scintillator panel 1 according to the first embodiment. The substrate of the second test body was a substrate in which a protective film including an organic material as a main component was formed on an aluminum base body. The second test body corresponds to a scintillator panel according to a reference example. The substrate of the third test body was the same as the substrate of the second test body. The constitutions of the first to third test bodies are as follows. First test body: a substrate made of an organic material, a barrier layer, and a scintillator layer. Second test body: a substrate having an organic layer, a barrier layer, and a scintillator layer. Third test body: a substrate having an organic layer, (no barrier layer), and a scintillator layer. The resolution of each of the first to third test bodies was obtained. The resolutions were adopted as reference values. Next, the first to third test bodies were installed in an environment testing machine in which the temperature was 40° C. and the humidity was set to 90%. Next, the resolution of each of the test bodies was obtained every predetermined time elapsed from the installation time. Then, the degrees of the ratios of the resolutions obtained with lapse of every predetermined time to the resolutions (reference values) were calculated. That is, relative values with respect to the resolutions before the test bodies were installed in the environment testing machine were obtained. For example, when the relative value was 100 percent, it indicated that the resolution obtained after the predetermined time elapsed did not change with respect to the resolution before the test bodies were installed in the environment testing machine and the performance did not deteriorate. Accordingly, it indicated that as the relative value becomes smaller, characteristics of the scintillator panel deteriorate. A graph shown in FIG. 13 shows a relationship between the time being exposed to the foregoing environment (horizontal axis) and the relative value (vertical axis). The resolution of the first test body was measured after an hour, after 72 hours, and after 405 hours from the installation time. Measurement results were indicated as plots P1a, P1b, and P1c. The resolution of the second test body was measured after an hour, after 20.5 hours, after 84 hours, and after 253 hours from the installation time. Measurement results were indicated as plots P2a, P2b, P2c, and P2d. The resolution of the third test body was measured after an hour, after 24 hours, after 71 hours, and after 311 hours from the installation time. Measurement results were indicated as plots P3a, P3b, P3c, and P3d. The measurement results thereof were confirmed that performance of the third test body (plots P3a, P3b, P3c, and P3d) having no barrier layer deteriorated the most among the first to third test bodies. It was assumed that deterioration in performance occurred in the third test body because moisture percolated from the organic layer to the scintillator layer and deliquescence of the scintillator layer progressed with lapse of time due to the percolated moisture. On the other hand, regarding the first and second test bodies (plots P1a, P1b, and P1c; and plots P2a, P2b, P2c, and P2d) as well, it could be confirmed that the relative values tended to drop with the lapse of time. However, it was obvious that the degrees of drop in relative value indicated by the first and second test bodies were further curbed than the degree of drop in relative value indicated by the third test body. Accordingly, it has been found that deterioration in characteristics of a scintillator panel can be curbed by providing a barrier layer including TlI as a main component. It has been found that a barrier layer including TlI as a main component can contribute to improvement in moisture resistance of a scintillator panel. 1, 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1K Scintillator panel 2, 2A Substrate 2a Substrate front surface 2b Substrate rear surface 2c Substrate side surface 3, 3A, 3B Barrier layer 3a Barrier layer front surface 3b Barrier layer rear surface 3c Barrier layer side surface 4, 4A, 4B Scintillator layer 4a Scintillator layer front surface 4b Scintillator layer rear surface 4c Scintillator layer side surface 5, 5A, 5B Melted region 5a, 5b Melted portion 6, 6C, 6D Protective film 6A, 6B Protective sheet 6a, 6b Sheet member 7, 7A, 7B Laminated body 7a Laminated body front surface 7b Laminated body rear surface 7c Laminated body side surface 8, 8A, 8B, 8C Functional layer 8a Functional layer front surface 8b Functional layer rear surface 8c Functional layer side surface 9 FOP 9a FOP front surface 9b FOP rear surface 9c FOP side surface 10, 10A, 10B, 10C, 10D, 10E, 10F, 10G, 10H, 10L, 10K, 10M Radiation detector 11 Sensor panel 11a Panel front surface 11b Panel rear surface 11c Panel side surface 12, 12A Sealing portion 12B Sealing sheet 12a Outer circumferential edge 12C Sealing frame 13, 13A, 13B Sealing frame 13a Frame front surface 13b Frame rear surface 13c Frame wall portion 14 Sealing plate 14a Plate front surface 14b Plate rear surface 14c Plate side surface 16 Photoelectric conversion element 17 Inner sealing frame 18 Outer sealing frame 15 Adhesive S1 Photo-detection region S2 Surrounding region S3 Exposed region S2a Peripheral region
041486862	description	DETAILED DESCRIPTION The heat exchanger module, which can be grouped in parallel with other modules, includes a jacket or outer casing 1 having a generally cylindrical shape, inside which is disposed a coaxial inner casing 2 surrounding a nest of tubes 3, comprising a large number of parallel tubes, not shown. The nest of tubes 3 is connected to a lower tubular plate 4 and to an upper tubular plate 5, the tubes forming at their top part an expansion-bend 6. The nest of tubes is intended to convey the flow of water which is to be heated to superheated steam. The water is admitted at the bottom part of the module through tubing 7 and is discharged in the state of superheated steam at the upper part through tubing 8. An annular space 9 disposed in the upper part of the module between the casings 1 and 2 is connected to inlet tubing 10 for liquid sodium heated in a rapid neutron nuclear reactor. During normal operation, the liquid sodium rises between the casings 1 and 2, then flows into the casing 2 around the tubes of the nest 3, in opposition to the flow of the water which is to be vaporized and superheated. An annular space 11 disposed in the lower part of the module between the casings 1 and 2 is connected to tubing 12 for discharging the liquid sodium cooled in the exchanger. The casing 1 of the module is surrounded over its entire height between the annular inlet space 9 and the outlet space 10 with a coaxial outer casing or jacket 13 defining an annular space 14 with casing 2. This space 14 is connected to an ambient air inlet tube 15 and an ambient air outlet tube 16. A blower 17 ensures the circulation of air in the annular space 14. Horizontal spikes 18 are provided over the entire height of the outer surface of the casing 1 that is under the jacket 13. The spikes 18 serve to improve the heat exchange coefficient between the liquid sodium and the air blown through the space 14 when the nuclear reactor is shut down. When a rapid neutron nuclear reactor is shut down, the power which it supplies does not die away immediately, but decreases gradually. As the flow of water must be stopped on shut down, the residual power must be dissipated elsewhere until its supply has died away. This dissipation is effected by heat exchange between the sodium and the air flowing in the annular space 14 in the direction shown by arrows 19, 20. However, as the heat exchange coefficient of air is relatively low, it is improved by the use of the spikes 18 so as to ensure the dissipation of the residual heat with a moderate air flow. The spikes 18 are immersed in the air flow and may have a height which is of the order of half the width of the annular space 14. These spikes 18 could be replaced by other auxiliary heat exchange means, such as vertical fins. When the residual power generated by the nuclear reactor has greatly decreased, it is possible to stop the air blower as the natural air flow by convection becomes sufficient to dissipate the remaining fraction of residual power. If the water/sodium heat exchanger is composed of several modules grouped together in parallel, it is preferable to provide only one blower feeding air to the coverings of the various modules through appropriate tubes. Although the structure of the heat exchange module which has just been described appears to be preferable, it will be understood that various modifications can be made thereto without going beyond the scope of the invention, it being possible to replace particular elements described by others which fulfill the same technical function.
	summary
	claims	1. A system for attenuating scatter radiation during a radiological procedure using a radiation machine including an emitter, a receiver, a base, and a table for a patient, the base being supported by a floor, the system comprising:a barrier formed of radiation attenuation material, the barrier having a durometer of less than 100 shore “00” and being configured to fit below the table, be disposed over an area on the floor, and extend from the table at an operator position. 2. The system of claim 1, wherein the barrier is provided between a support for the table and the base of the radiation machine. 3. The system of claim 2, wherein the barrier extends past a lateral side of the table. 4. The system of claim 3, wherein the barrier extends past the lateral side by a distance of at least one foot. 5. The system of claim 1, wherein the barrier is L-shaped. 6. The system of claim 5, wherein the barrier is comprised of an elastomeric matrix. 7. The system of claim 6, wherein an operator stands on at least a portion of the barrier during the procedure. 8. The system of claim 1, wherein the barrier is placed partially over the base of the radiation machine. 9. The system of claim 8, wherein the base of the radiation machine is C-shaped. 10. The system of claim 9, wherein the barrier is between 0.03 and 1.0 inches thick. 11. The system of claim 1, wherein the barrier has an area of at least 8 square feet. 12. The system of claim 1, wherein the table includes a radiation attenuation skirt. 13. The system of claim 1, wherein the barrier is provided under the emitter and above the base of the radiation machine at a location of the emitter. 14. A system for use with a radiation machine comprising an emitter disposed beneath a table for performing a radiation procedure, the system comprising:a floor mat configured to be disposed beneath the table and over an area on a floor, the floor mat being comprised of radiation attenuation material, the floor mat being between ⅛ and ¼ of an inch thick. 15. The system of claim 14, wherein the radiation machine is a fluoroscope. 16. The system of claim 15, wherein the floor mat is configured to fit between the emitter and a bottom portion of a C-shaped support base of the radiation machine. 17. The system of claim 16, wherein the floor mat extends past a lateral side of the table by at least one foot. 18. A method of performing a radiological procedure on a patient, the method comprising:placing a radiation attenuation mat on a floor beneath a table, wherein the patient is disposed on the table for the radiological procedure; andproviding radiation to the patient, wherein the radiation attenuation mat reduces 53% to 95% of radiation level tested at a position 60 inches from the floor. 19. The method of claim 18, wherein the radiation attenuation mat reduces scatter radiation at a location off a head of the patient by more than 25 percent. 20. The method of claim 18, wherein the radiation attenuation mat reduces scatter radiation at a location off the left side of the patient by more than 25 percent.
	abstract	A collimator capable of being reduced in its external size without sacrificing an aperture is to be provided. To this end, the collimator comprises a pair of first plate members which defines a radiation passing aperture by a spacing between respective opposed end faces, a pair of second plate members which respectively overlap the first plate members at least partially so as to block any other radiation than the radiation passing through the aperture, a pair of third plate members which respectively overlap the second plate members at least partially so as to block any other radiation than the radiation passing through the aperture, an adjusting mechanism which adjusts the aperture by moving the pair of first plate members, and a follow-up mechanism which causes the pair of second plate members to move following the pair of first plate members with movement of the first plate members.
	abstract	A fluoroscopic system is disclosed with capability of differential exposure of different input areas of an image intensifier. The x-ray beam solid angle is limited by a collimator that is relatively near to the focal point of the x-ray tube, to occupy an area smaller then the input area of the image intensifier. Means to deflect the electron beam of the x-ray tube in two dimensions are constructed with the x-ray tube to provide scanning capability of the complete input area with full control on the motion function. The collimator may also be moved to control beam size and/or position at the image intensifier.
	summary
051568039	description	DETAILED DESCRIPTION In the following description, the terms "axial", "radial" and "tangential" are used to refer to directions relative to the reactor vessel. "Axial direction" relates to a direction parallel to the axis of the reactor vessel, "radial direction" relates to a direction from the center of the reactor vessel towards the wall thereof perpendicular to the axial direction, and "tangential direction" relates to a direction perpendicular to the axial as well as the radial direction. The terms "upper", "lower", "upwards" and "downwards" also relate to the reactor vessel, assuming that the reactor vessel has its axis oriented vertically to the opening at the upper part of the reactor vessel. FIGS. 1 and 2 show a prior art device of the kind disclosed in the background of the invention mounted on a reactor vessel having its cover removed. Typically, the upper part of a wall of a substantially cylindrical reactor vessel 1 is immersed into a water-filled pool (not shown). A flange 3 surrounds the opening 2 of the reactor vessel forming a circular running surface along which an upper trolley 4 can be moved by means of a drive device. The trolley 4 is connected to a distance beam 5 which supports a support mast 6 built of a number of sections and extending substantially parallel to the reactor vessel wall. A support tube 8 affixed to the support mast rests against pin bolts 7 which fasten the reactor vessel cover. Two support wheels 9A, 9B are also mounted on the support tube 8. When the support mast 6 has been moved into the reactor vessel, the support wheels 9A, 9B are moved against the wall of the reactor vessel activation of compressed-air cylinders associated with the support wheels. The support wheels thus fix the radial distance between the upper part of the support mast and the wall of the reactor vessel. A support arm 100 with two guide wheels 10A, 10B, is located at the lower part of the support mast. With the support arm in extended position, the guide wheels contact the reactor vessel wall. The length of the support arm may be adjusted by means of a compressed-air cylinder to vary the radial distance between the lower part of the support mast and the rector vessel wall. Since the reactor vessel contains non-dismantled feed water spargers 11 and core spray spargers 12, the distance between the guide wheels and support arm is adjusted so that the support mast, which in the rector vessel reaches down to a level just below the feed water spargers 11, may pass radially inside the feed water spargers 11 when inserted into the reactor vessel. At the lower part of the support mast, a lower trolley 13 is arranged which is movable in relation to the support mast both in the radial and the axial direction. The trolley 13 supports an extension mast 14, which has an end effector 15 comprising an inspection member with probes of ultrasonic type located at its lower portion. The lower trolley is initially in its radially inner position and axially upper position (shown in FIG. 1) when the support mast is inserted into the reactor vessel so that the extension mast clears the feed water spargers 11. When the lower part of the support mast 6 has cleared the feed water spargers 11, the lower trolley 13, as indicated in dashed lines in FIG. 1, may be moved outwards in the radial direction under the feed water spargers to a position where the inspection member makes contact with the reactor vessel wall. It is then possible to move the lower trolley in the downward axial direction in the reactor vessel to further increase the interior portion of the reactor vessel which is available for inspection. However, since the length of the extension mast is limited by the axial distance between the feed water spargers 11 and the cover 16 of a core shroud 17 positioned in the reactor vessel, the lower trolley can only be moved downwards a distance corresponding to the length of the extension mast. Therefore, this apparatus generally does not allow inspection of weld joints located in the lower part of a reactor vessel. FIGS. 3 and 4 show an apparatus for inspection of a reactor vessel according to the present invention. The apparatus includes a trolley 4 and drive means, as well as a support mast 6 mountable to the reactor vessel wall in the same manner as the prior art. However, the apparatus contains many additional features. A tilting device 18, which is connected to the support arm 100, includes an arm 182 having a support wheel 183. The angle of the support mast 6 relative to the reactor wall is adjusted by a compressed-air cylinder 181 connected to the support mast 6 and support arm 100. A vertical trolley 141 is affixed to the upper part of an extension mast 14. This trolley 141 is movable along the support mast 6 via a chain, as suggested in the FIGS. 3 and 4. A mast guide 19 is arranged at the lower part of the support mast to guide the extension mast during its axial movement. A surveillance camera 21, shown in FIG. 3, is mounted at the lower part of the support mast to visually check that there are no obstacles present when lowering the extension mast down into the reactor vessel. The lower part of the extension mast 14 supports an end effector 15 inspection member with ultrasonic type probes. At the lower part of the support mast a maneuverable arm comprising a locking device 20, shown in FIG. 4, is connected thereto. The core shroud cover 16 of the reactor vessel contains a number of lugs 161A, 161B arranged in pairs and radially projecting from cover 16. The locking device can be moved down between a pair of the lugs 161A, 161B, by means of a compressed-air cylinder to lock the support mast in a tangential direction to the reactor vessel, as shown in FIG. 5. Referring again to FIG. 3, when the apparatus is moved into the reactor vessel, the tilting device is in its extended position and the extension mast in its upper position. The support wheel 183 makes contact with the wall of the reactor vessel, and the length of the arm 181 is set to allow the support mast 6 create a sufficiently large enough angle with the reactor vessel wall 1 to allow the end effector 15 to pass by the feed water spargers 11. When the end effector 15 has passed the feed water spargers 11, the tilting device is adjusted to its retracted position to move the end effector radially towards the vessel wall 1. Referring to FIG. 4, the tilting device 18 is in its retracted position such that the support mast and the extension mast are positioned substantially parallel to the reactor vessel wall and the extension mast has been moved axially downwards along the support mast. The distance beam 5, the support mast 6, the vertical trolley 141 and the extension mast 14 are dimensioned to allow the extension mast to pass through the annular shaped area below the feed water spargers and between the vessel wall 1 and the core shroud cover 16. In this position the inspection member may contact the vessel wall. Therefore, the length of the extension mast and the region available for inspection in the axial direction below the feed water spargers 11 is not dependent on the axial distance between the feed water spargers 11 and the core shroud cover 16. The space available for the insertion of the extension mast 14 into the gap between the reactor vessel wall 1 and the core shroud 16, (projected on a plane perpendicular to the axis of the vessel, as shown in FIG. 5), is greatly restricted. In the radial direction, the outer boundary line of the available space consists of the projection of the feed water spargers 11 in the plane while the inner boundary lines consist of either the core shroud 16 or the core spray spargers (not shown). In the tangential direction, the boundary lines, consist of the projections of the lugs 161A, 161B on the core shroud cover. The available space may typically consist of part of a circular ring with a radial extension of about 70 mm and a length in the tangential direction of 330 mm. Also, in certain reactors, jet pumps 22, as shown in FIG. 6, are positioned in the gap between the reactor vessel wall 1 and the core shroud. The upper part of these jet pumps 22 are usually located at a level below the core shroud cover and are normally secured to the reactor vessel wall by brackets 221. Therefore, a device with an end effector 15 fixed to the extension mast 14 cannot reach all parts of a tangentially extending weld joint. FIGS. 7-9 show the lower part of the extension mast 14 with an end effector 15 affixed thereto by means of a flexible support arm 231. Referring to these Figures, a main frame 232 is affixed to the lower part of the support arm 231. Associated with the main frame is an upper drive device 24, a lower drive device 25 and a compressed-air cylinder 26. The upper drive device 24 includes an electric motor 419, an incremental position transducer 421 and a gear box 423 (shown in detail in FIG. 17). Referring to FIG. 9, the upper drive 24 drives a chain 241 connected to two gear wheels 27A, 27B within the main frame 232, to displace a rack 28 which is movable in the tangential direction relative to the main frame 232. A horizontal trolley 29, affixed to rack, may be translated from a central position, where its central line is located opposite to the central line of the extension mast (shown in FIG. 8), to outer positions on either side of the central line of the extension mast (shown in FIG. 9) by activating the upper drive device 24. As shown in FIG. 8, circular holes have been provided in the horizontal trolley and the probe position trolley to reduce their weight. Referring to FIGS. 8 and 9, a probe position trolley 30 functions to move the probe holder tangentially relative to the horizontal trolley. The probe position trolley 30 is initially locked in position to the horizontal trolley 29 and supports a probe holder 31 to which four ultrasonic type probes 311, 312, 313, 314 are resiliently clamped. The probe position trolley 30 and the probe holder 31 are fixed to each other by means of a shaft 315 which is controlled by the lower drive device 25. A compressed-air cylinder 233, operatively connected the support arm 231, allows the support arm to be rotated around the bearing 234 inwards towards the extension mast. The lower drive device 25, shown in detail in FIG. 17, includes an electric motor 425 which is adapted to activate a compressed-air cylinder 26 and rotate the probe position trolley around the shaft 315 to temporarily unlock the shaft from the horizontal trolley 29. Referring again to FIG. 7, the main frame 232 can be adjusted in a radial direction where the probe holder 31 does not make contact with the reactor vessel wall. The bearing 234 is spring-prestressed to apply a constant counterclockwise torque to the support arm. Therefore, when the compressed-air cylinder 233 is deactivated, the support arm 231 pivots away from the extension mast 14 to a position where the probe holder 31 makes contact with the reactor vessel wall 1. Referring to FIG. 3, when the apparatus is lowered down into the reactor vessel, the tilting device 18 of the support mast 6 is in an extended position, the probe holder 31 is in the retracted position and the extension mast 14 is in the upward position along the support mast 6. Furthermore, the horizontal trolley is in its central position. The end effector is then allowed to pass in a radial direction inside the feed water spargers 11 whereupon the tilting device 18 is retracted. The extension mast 14 may now be lowered further, for example, to a level below the upper brackets of the jet pumps, allowing the main frame 232 to pass between the brackets (as shown in FIG. 6). When the desired level has been reached, the compressed-air cylinder 233, shown in FIG. 7, is deactivated, causing the support arm 231 to be moved by the spring loaded bearing 234 against the vessel wall 1 so that the probe holder will make contact with the vessel wall with a predetermined contact pressure suitable for proper functioning of the probes. The horizontal trolley 29 can now be moved, as indicated in FIG. 9, for example, from its central position in a counterclockwise direction. The probe position trolley 30 and the probe holder 31 will move with the horizontal trolley 29 for inspection of, for example, a horizontally extending weld joint in the vessel. The weld joint can then be scanned for inspection in a clockwise direction. To provide the probe holder 31 with maximum reach in either tangential direction relative to the extension mast 14, the probe position trolley 30 may also be moved tangentially relative to the horizontal trolley 29. FIGS. 10A-C show various positions of the horizontal trolley 29 relative to the main frame 232 and multiple positions of the probe position trolley relative to the horizontal trolley 29. The wall 1 of the reactor vessel is marked in each of the three situations by the circular arcs A--A, B--B and C--C, respectively. Description of the scanning procedure will be described assuming that scanning of the reactor vessel wall is first performed when the horizontal trolley is situated to the left of the central position, as shown in FIG. 10A, and the probe position trolley 30 is located at the lefthand edge of the horizontal trolley. First, when the horizontal trolley has reached its outer lefthand end position (shown arc A--A), it is moved back to central position as shown in FIG. 10B (arc B--B), while scanning is performed. The probe position trolley 30 is then moved from the lefthand edge of the horizontal trolley to the righthand edge of the horizontal trolley. While scanning, the horizontal trolley is then moved from the central position to the position shown in FIG. 10C (arc C--C). The movement of the probe position trolley 30 relative to the horizontal trolley 29 is carried out in three steps. Initially, the probe position trolley 30 is locked to the left hand edge of the horizontal trolley 29. From the position shown in FIG. 10A , the horizontal trolley 29 is moved clockwise so that the center of the probe position trolley 30 is aligned with the center line of the extension mast 14. Thereafter, a push pin 32, as shown in FIG. 8, is activated with the aid of a compressed-air cylinder (not shown). The push pin passes through the hole 33 in the front plate of the probe position trolley 30 thus locking the probe position trolley 30 to the main frame. In the next step, the horizontal trolley 29 is unlocked from the probe position trolley 30 by activation of the compressed-air cylinder 26 (FIG. 7) which displaces a spring-loaded locking pin 427 (FIG. 17) arranged in the shaft 315. The probe position trolley 30 is then rotated 45.degree. around the shaft 315 by the lower drive device 25. The compressed-air cylinder 26 is now deactivated, the spring-loaded locking pin partially returns to its original position and the probe position trolley 30 remains disengaged from the horizontal trolley 29. The horizontal trolley 29 is then moved counterclockwise, by means of the upper drive device 24, until the probe position trolley 30 is positioned at the righthand edge of the horizontal trolley 29. At this time, the compressed-air cylinder 26 is activated to displace the spring-loaded locking pin 427 and the lower drive device 25 rotates the probe position trolley 45.degree. back to its original position. The compressed-air cylinder 26 is deactivated and the spring loaded locking pin 427 completely returns to its original position locking the probe position 30 trolley to the horizontal trolley 29. Finally, the push pin 32 is deactivated so that the probe position trolley 30 is disengaged from the main frame 232. The effector 15 may be moved to inspect the righthand part of the vessel wall with maximum reach. Although the probe position trolley may be moved relative to the horizontal trolley, the area of the vessel wall which is directly in front of the main frame may be inspected with the probe position trolley in either lefthand or righthand positions. The present invention allows inspection with ultrasonic probes even when the probe holder is to be rotated about its axis in steps of 90.degree. in accordance with certain inspection patterns. This rotation is performed by the following steps. The horizontal trolley 29 is moved so that the center of the probe position trolley 30 is opposite center of the extension mast. In the next step, the horizontal trolley is unlocked from the probe position trolley 30 by the compressed-air cylinder 26 displacing the spring-loaded locking pin 427, as mentioned supra. The probe position trolley is rotated 90.degree. by lower drive device 25, the compressed-air cylinder 26 is deactivated and the spring-loaded locking pin 427 completely returns to its original position locking the probe position trolley to the horizontal trolley. The angular position of the probe position trolley 30 relative to the horizontal trolley 29 is locked by four guide pins 429 (shown in FIG. 17) passing into slots provided in the hub of the probe position trolley. The guide pins 429 may be inserted in the slots when the spring-loaded locking pin 427 returns to the lock position. If jet pumps 22 are positioned between the core shroud 16 and the reactor vessel wall 1, the apparatus allows the region below and between the upper brackets of the jet pumps to be available for inspection. As is shown in FIG. 6, the brackets 221 of the jet pumps 22 prevent the end effector 15 from being raised out of the reactor vessel when the horizontal trolley 29 is in extended position below these brackets 221. However, when the horizontal trolley 29 is not extended, the end effector 15 may be raised between the brackets 221. The horizontal trolley 29 includes a completely mechanical system for manually returning the horizontal trolley to its central position in case of a fault in the upper drive device 24. A rope 401 shown in FIG. 17, affixed to the horizontal trolley 29 passes through a turntable at the edge of the main frame 232 and then passes through a hole bored through the gear box output shaft end 415 in the upper drive device 24 in a plane perpendicular to the shaft end. The rope also passes over other turntables (not shown) along the extension mast. The end of the rope is affixed an eye accessible from the opening of the reactor vessel. If a fault is determined in the upper drive device 24. A tool mounted on a rod may be lowered down to engage the eye. Initially, the tension in the rope may not be able to overcome the friction of the gear box and drive device. When the rod is raised, the tension will, however, displace the shaft end in an axial direction, via the hole bored in the output shaft end of the gear box, disengaging the gear box and the chain transmission 421 with the gear wheels 27A, 27B. Continued pulling of the rope will now result in the horizontal trolley 29 being pulled in towards its central position. The position transducer of the drive device 24 remains mechanically connected to the chain transmission 24 and the movement of the horizontal trolley 29 by means of the rope may continue until the position transducer indicates that the horizontal trolley is in its central position. When the pulling of the rope ceases, the shaft end is returned to its original position by a spring device (not shown). Since the apparatus may be required to extend 70 mm in the radial direction and 330 mm in the tangential direction of the support mast length may typically be about 5 m, the apparatus includes a radial direction fine positioning system and a tangential direction fine position system. Particularly in case of in-situ constructed reactor vessels which may exhibit irregularities on their inner walls, it may be necessary to additionally fine position the extension mast 14 to facilitate optimum contact of the probe holder 31 or to prevent the mast 14 from interfering with parts of the reactor vessel wall 1. FIG. 11 shows a side view of the tangential direction fine position system and FIG. 12 shows the system from viewed above. A positioning arm 34, arranged at the lower part of the support mast, may be rotated about a bearing 342 by activation of a compressed-air cylinder 341 in an axial plane. An inductive type distance measuring device 343 is fixed to the positioning arm. The tangential positioning is performed by rough positioning the support mast 6, with the extension mast 14 in its upper position and the position arm 34 in an upper position, as shown by the broken line in FIG. 11. The position transducer system connected to the trolley 4 enables the positioning of the arm 34 to be safely within the available area in the tangential direction. In the next step, the compressed-air cylinder 341 is activated causing the arm 34 to be moved to a position, as shown by the unbroken line in FIG. 11, where the distance measuring device 343 is able to measure the distance to a lug 161B on the core shroud. The trolley 4 then moves the support mast 6 to a position where the distance measuring device 343 indicates a predetermined distance. In this position, the support mast is locked mechanically in the tangential direction by means of the locking device 20 described su in FIG. 5. FIG. 13 shows a sectional view of the radial direction fine positioning system and FIG. 14 shows a section along the line 14--14 in FIG. 13. The system comprises a part 35 which is fixed to the trolley 4 and rotatable by means of a drive device. A nozzle 351 provided in the part 35 is able to radially displace the beam 5 to which the support mast 6 is affixed. To make radial movement possible, the connection 361 between the distance beam and the nozzle permits radial play. The distance from the extension mast 14 to the vessel wall 1 is measured with an ultrasonic distance transducer (not shown). Inspection of all the accessible weld joints of a reactor vessel may typically take about 10 days. Test regulations require that the signal level of the probes be regularly verified. Typically verification must be done at 12 hour intervals and is usually carried out by transferring the probes to a simulation block 37, shown in FIG. 5. In order to shorten the time expenditure for moving the probes from their inspection position to the verification position, the simulation block is placed at the lower edge of the support mast, as shown in FIGS. 5, 15 and 16. The simulation block is connected to an arm 38, shown in FIG. 15, in which a holder 381 holds the simulation block 37. By means of a compressed-air cylinder 382, the arm 38 is movable between two positions, a retracted position (indicated in broken lines FIG. 15) and an extended verification position (shown in unbroken lines in FIG. 15). To perform verification, the extension mast 14 is pulled up to its upper position along the support mast 6, and the tilting device 18 is then activated. In the next step, the compressed-air cylinder 382 is activated and the simulation block is brought to the verification position. Thereafter, the horizontal trolley 29 is moved to its end position where the end effector passes by the simulation block. After verification has been performed, the horizontal trolley 29 is returned to its central position, the simulation block 37 is returned to its retracted position and the tilting device 18 is deactivated. The trolley 4, vertical trolley 141, horizontal trolley 29, and probe position trolley 30 may all be controlled remotely by activation of individual drive devices electronically interfaced to a control location outside the reactor vessel. Therefore, operation of the apparatus and control of its functions may be accomplished independently without the need for a physical presence within the reactor. Although the invention has been described in connection with the embodiments depicted herein. It will be apparent to one skilled in the art that various modifications, substitutions and equivalents may be used in connection with these embodiments. Any such variations are intended to be within the scope of the invention as defined by the following claims.
054597676	description	DETAILED DESCRIPTION OF THE INVENTION The present invention involves a unique and highly efficient method for testing the strength and structural integrity of nuclear fuel particles which are substantially spherical in shape and are typically characterized as "microspheres". As previously indicated, recent developments in nuclear energy have resulted in the production of high temperature gas reactor systems hereinafter designated as "HTGR" reactors. These reactors typically use nuclear fuel particles or microspheres of the type described above. To ensure that a supply of particles destined for use in an HTGR system will remain physically intact and viable during nuclear fission, it is desirable to test selected particle samples for strength and structural integrity. Adequate structural integrity and particle strength are likewise important to ensure that fission products are retained within the fuel particles during use. The leakage of fission products from the particles is undesirable because they are radioactive and could be detrimental to the health and safety of workers if released from the HTGR system. The specific fission products which are generated during the production of nuclear energy will vary, depending on the type of fissionable nuclear material being used in the particles. For example, fissionable nuclear material consisting of .sup.235 UCO (e.g. uranium-235 carbonate) will generate fission products consisting of .sup.133 Xe, .sup.134 Cs, .sup.85m Kr, .sup.105 Pd, .sup.134 Ba, .sup.144 Ce, and others. Regarding strength and structural integrity levels, it is generally preferred that nuclear fuel particles selected for use in HTGR reactors be capable of withstanding applied forces (both internally and externally generated) that result in tensile stresses within the barrier (e.g. silicon carbide) layer of about 100-500 MPa. Stress concentrations due to irradiation-induced structural changes in the various carbon layers may, in fact, lead to stresses of up to about 2500 MPa. However, these values will necessarily vary in view of the particular nuclear fuel materials being used. A. Nuclear Fuel Particles to be Tested As noted above, the present invention shall not be limited to any particular nuclear materials, barrier layers, or protective layers in the nuclear fuel particles to be tested. In this regard, nuclear fuel particles/microspheres of many different types and compositions may be tested for strength and structural integrity. While the invention described below shall not be limited to any particular nuclear fuel particles, an exemplary nuclear fuel particle 10 is illustrated in FIGS. 1-2. With reference to FIGS. 1-2, a particle 10 substantially spherical in configuration is schematically shown which includes a hemispherical upper portion 12 and a hemispherical lower portion 14, with the upper portion 12 being equal in size to the lower portion 14. As illustrated in FIG. 1, the juncture where the upper portion 12 meets the lower portion 14 is shown at dashed dividing line 15. The particle 10 further includes a spherical center region 16 (FIG. 2) consisting of a selected fissionable radioactive (nuclear) composition. A preferred radioactive composition suitable for use in the center region 16 is a spherical portion of .sup.235 UCO (uranium-235 carbonate) having a diameter of about 200 .mu.m. Other compositions suitable for use in the center region 16 include but are not limited to .sup.235 UC.sub.2, .sup.232 ThC.sub.2, and .sup.239 PuC.sub.2, with a preferred diameter range for the center region 16 being about 200-600 .mu.m. In tritium production systems, the center region 16 may consist of .sup.6 Li compounds (e.g. LiAl.sub.5 O.sub.8 and LiAlO.sub.2). Surrounding the center region 16 in the particle 10 of FIG. 2 is a buffer layer 18 which is primarily designed to provide volume in order to retain fission or reaction gases (e.g. .sup.133 Xe, .sup.85m Kr, and CO) within the particle 10. A preferred composition suitable for use as the buffer layer 18 consists of pyrolytic carbon applied by conventional fluidized bed chemical vapor deposition techniques at a uniform thickness of about 100 .mu.m. Also included within typical fuel particles suitable for use in HTGR reactors are one or more protective layers In the particle 10 of FIGS. 1-2, an inner protective layer 20 is provided which entirely surrounds the buffer layer 18. A preferred composition suitable for use as the inner protective layer 20 consists of pyrolytic carbon applied by conventional fluidized bed chemical vapor deposition techniques at a uniform thickness of about 40.mu.m. The inner protective layer 20 is likewise designed to retain fission gases and other fission/reaction products within the particle 10, and also provides added strength. Entirely surrounding the inner protective layer 20 within the particle 10 is least one barrier layer 22 which, in the embodiment of FIGS. 1-2, is manufactured from SiC (silicon carbide) at a uniform thickness of about 35 .mu.m. The barrier layer 22 generally provides the nuclear fuel particle 10 with a significant and dominant part of its structural integrity, and serves to function as the primary barrier regarding the escape of fission/reaction products from the particle 10 during use in a reactor. In a preferred embodiment involving the use of SiC as the barrier layer 22, the SiC is typically applied in a conventional manner by the thermal decomposition of methyltrichlorosilane. Other compositions suitable for use as the barrier layer 22 include but are not limited to ZrC, HfC, TaC, NbC, Si.sub.3 N.sub.r, SiAlON, and AlN applied conventionally at a uniform thickness of about 30-60 .mu.m. Entirely surrounding the barrier layer 22 is an outer protective layer 30. A preferred composition suitable for use as the outer protective layer 30 again consists of pyrolytic carbon applied by conventional fluidized bed chemical vapor deposition techniques at a uniform thickness of about 40 .mu.m. The outer protective layer 30 is again designed to retain fission gases and other fission/reaction products within the particle 10, and also provides some additional strength. Finally, the particle 10 shown in FIGS. 1-2 includes an optional external coating 32 which preferably consists of a still further layer of pyrolytic carbon applied by fluidized bed chemical vapor deposition techniques at a uniform thickness of about 45 .mu.m. The external coating 32 is designed to minimize damage to the particle 10 during handling and the like. The particle 10 illustrated in FIGS. 1-2 has a diameter D (FIG. 1) of about 360 .mu.m. In accordance with FIGS. 1-2, the diameter D.sub.1 of the particle 10 shall be equivalent to the maximum width of the particle 10 as taken at the juncture between the hemispherical upper portion 12 and hemispherical lower portion 14 shown at dashed line 15 in FIG. 1. However, the present invention shall not be limited to particles having any particular dimensional characteristics, with most nuclear fuel particles of interest having diameter values ranging from about 300-900 .mu.m. The particle 10 shown in FIGS. 1-2 and described above which involves a center region 16 manufactured from .sup.235 UCO and a barrier layer 22 comprised of SiC is conventionally known as a "TRISO" particle. This type of particle will normally have the following characteristics as indicated below in TABLE I: TABLE I ______________________________________ Property Mean Value ______________________________________ Total uranium (wt. %) >87.0 .sup.235 U enrichment (wt. %) 93.15 (+0.15, -1.00) Carbon/uranium atomic ratio >0.5 Oxygen/uranium atomic ratio 1.4-1.7 Density (Mg/m.sup.3) >10.3 ______________________________________ However, as noted above, the present invention shall not be limited to nuclear fuel particles having the foregoing components and numerical parameters. Other fuel particles involving different characteristics and components may also be tested in accordance with the invention. Exemplary fuel particles of the type described herein which can be tested using the methods described below are available from the following commercial sources: General Atomics, Inc. of San Diego, Calif. (U.S.A.); British Nuclear Fuels, Plc of Salwick Preston, UK; CEGA, Inc. of San Diego, Calif. (U.S.A.); Babcock & Wilcox, Inc. of Lynchburg, Va. (U.S.A.); Kernforschungsanlage, Julich GmbH of Julich, Germany; and NFS of Erwin, Tenn. (U.S.A.). As previously noted, further information regarding HTGR systems and nuclear fuel particles used in HTGR systems is described in the following articles which are incorporated herein by reference: Tennery, V. J., et al., "Structural Characterization of HTGR Pyrocarbon Fuel Particle Coatings", J. Am. Ceram. Soc., 60(5-6):268-274(1977); Stinton, D. P., et al., "Effect of Deposition Conditions on the Properties of Pyrolytic SiC Coatings for HTGR Fuel Particles", Ceramic Bulletin, 57(6):568-573(1978); Krautwasser, P., et al., "Raman Spectral Characterization of Silicon Carbide Nuclear Fuel Coatings", J. Am. Ceram. Soc., 66(6):424-433(1983); Smith, C. L., "SiC-Fission Product Reactions in HTGR TRISO UC.sub.2 and UC.sub.x O.sub.y Fissile Fuel: I., Kinetics of Reactions in a Thermal Gradient", J. Am. Ceram. Soc., 62(11-12):600-606(1979); and Allen, P. L., et al., "Nuclear Fuel Coated Particle Development in the Reactor Fuel Element Laboratories of the U.K. Atomic Energy Authority", Nucl. Technol., 35:246-253(1977). B. Testing Methods A main goal of the present invention is to provide a highly efficient testing method which avoids the need to perform physical dissection of the test particles while enabling the distribution of compressive forces over a broad area on each particle. As a result, more comprehensive and sensitive testing of individual particles for widely-distributed internal flaws is provided. Further information regarding benefits of the present invention compared with prior test methods is provided below. With reference to FIGS. 3-5, a testing apparatus 50 is provided which may involve may different forms as discussed herein. However, key elements of the testing apparatus 50 include an upper compression member 52 which preferably comprises a planar disk-type structure 54 which is circular in cross-section. Regardless of form, the compression member 52 is manufactured from a material having a hardness level greater than that of the particle 10 described above (or any other nuclear fuel particles being tested by the apparatus 50). In a preferred embodiment, the upper compression member 52 is comprised of Type 304 stainless steel (especially if a "TRISO"-type particle of the composition described above is to be tested). Other materials suitable for use in connection with the upper compression member 52 include but are not limited to (1) other chromium-nickel stainless steels such as Type 316, Type 201, Type 310, and Type 347; (2) plain carbon steels such as Type 1010 through Type 1095; (3) alloy steels such as Type 1330, Type 2330, Type 3130, Type 4130, and Type 4140; and (4) hard ceramic materials such as alumina, zirconia, silicon carbide, and silicon nitride. In this regard, production of the upper compression member 52 shall not be limited to any particular construction material, provided that the selected material has a hardness level which exceeds that of the fuel particle (e.g. particle 10) being tested or consists of a stiff metal that can be indented, with the area surrounding the indent being strain hardenable during indentation. While the upper compression member 52 shown in FIGS. 3-4 is illustrated in the form of disk-type structure 54, the compression member 52 may be configured in a wide variety of different forms including but not limited to planar, elongate structures which are square or rectangular in shape. Accordingly, the present invention shall not be limited to any specific shape or configuration regarding the upper compression member 52. The selected upper compression member 52 will optimally have a thickness T (FIG. 5) which exceeds the diameter of the particle being tested in the apparatus 50 (e.g. diameter D.sub.1 of particle 10 shown in FIG. 1). In addition, as specifically illustrated in FIG. 4, the upper compression member 52 includes an external first pressure-exerting surface 60 (preferably planar in configuration) which faces downwardly in the testing apparatus 50 as shown in FIGS. 3-5. Positioned at a selected location on the first pressure-exerting surface 60 (preferably at the center line C of the upper compression member 52 shown in FIG. 5) is at least one first dimple or depression 62. The first depression 62 (which is optimally hemispherical in configuration as illustrated) begins at the first pressure-exerting surface 60 and extends inwardly into the upper compression member 52 (FIG. 5). Within the upper compression member 52, the first depression 62 includes an internal cavity 64 which is surrounded by a continuous interior side wall 66 of annular design (e.g. circular in cross-section). With reference to FIG. 5, the presence of first depression 62 within the upper compression member 52 results in the formation of a circular rim portion 69 at a position where the first pressure-exerting surface 60 meets the interior side wall 66 of the depression 62. The first depression 62 is circular in cross-section along its entire length. In addition, the maximum diameter D.sub.2 of the first depression 62 (which consists of the diameter of the depression 62 at the first pressure-exerting surface 60 as shown in FIG. 5) will be less than the diameter of the selected fuel particle being tested (e.g. diameter D.sub.1 of particle 10). In a preferred embodiment, the diameter D.sub.2 of the first depression 62 will be about 30-60% of the diameter of the fuel particle of interest (e.g. diameter D.sub.1 of particle 10), with an exemplary diameter D.sub.1 range being about 60-600 .mu.m. As a result, the first depression 62 is sized to allow only part of the hemispherical upper portion 12 of fuel particle 10 therein (e.g. within the internal cavity 64) while preventing entry of all of the portion 12 into the first depression 62 as described in further detail below. Furthermore, it is preferred that the length (e.g. depth) L.sub.1 of the first depression 62 be less than the diameter of the selected fuel particle (e.g. diameter D.sub.1 of particle 10). These design features are of substantial importance in the present invention as described below. Also provided within the testing apparatus 50 as particularly illustrated in FIGS. 3 and 5 is a lower compression member 70 which is substantially identical to the upper compression member 52 in function, form, construction materials, dimensions, and purpose. In a preferred embodiment, the lower compression member 70 preferably comprises a planar disk-type structure 73 which is circular in cross-section. Regardless of form, the lower compression member 70 is optimally manufactured from a material having a hardness level equivalent to that of the upper compression member 52 and greater than the hardness of the particle 10 described above (or any other nuclear fuel particles being tested by the apparatus 50). In a preferred embodiment, the upper compression member 70 is again comprised of Type 304 stainless steel (especially if a "TRISO"-type particle of the composition described above is being tested). Other materials suitable for use in manufacturing the lower compression member 70 include but are not limited to (1) other chromium-nickel stainless steels such as Type 316, Type 201, Type 310, and Type 347; (2) plain carbon steels such as Type 1010 through Type 1095; (3) alloy steels such as Type 1330, Type 2330, Type 3130, Type 4130, and Type 4140; and (4) hard ceramic materials such as alumina, zirconia, silicon carbide, and silicon nitride. In this regard, production of the lower compression member 70 shall not be limited to any particular construction material, provided that the selected material has a hardness level which exceeds that of the fuel particle being tested (e.g. particle 10) or consists of a stiff metal that can be indented, with the area surrounding the indent being strain hardenable during indentation. While the lower compression member 70 shown in FIGS. 3-4 is illustrated in the form of disk-type structure 73, the lower compression member 70 may be configured in a wide variety of different forms including but not limited to planar structures which are square or rectangular in shape. The configuration of the lower compression member 70 should preferably correspond with the selected shape of the upper compression member 52. Nonetheless, the present invention shall not be limited to any specific shape or configuration regarding the upper and lower compression members 52, 70. The selected lower compression member 70 will optimally have a thickness T.sub.2 (FIG. 5) which exceeds the diameter of the particle being tested in the apparatus 50 (e.g. diameter D.sub.1 of particle 10 shown in FIG. 1). In addition, the lower compression member 70 includes an external second pressure-exerting surface 74 (preferably planar in configuration) which faces upwardly in the testing apparatus 50 as illustrated in FIGS. 3 and 5. Positioned at a selected location on the second pressure-exerting surface 74 (preferably at the center line C.sub.2 of the lower compression member 70 shown in FIG. 5) is at least one second dimple or depression 76. The second depression 76 (which is optimally hemispherical in configuration) begins at the second pressure-exerting surface 74 and extends inwardly into the lower compression member 70 as illustrated in FIG. 5. Within the lower compression member 70, the second depression 76 includes an internal cavity 80 which is surrounded by a continuous interior side wall 82 of annular design (e.g. circular in cross-section). In a preferred embodiment, the second depression 76 will be equal in size, shape, internal volume, depth, and overall configuration to the first depression 62. As illustrated in FIG. 5, the presence of the second depression 76 in the lower compression member 70 results in the formation of a circular rim portion 84 at a position where the second pressure-exerting surface 74 meets the interior side wall 82 of the second depression 76. The second depression 76 is also circular in cross-section along its entire length. In addition, the maximum diameter D.sub.3 of the second depression 76 (which involves the diameter of the second depression 76 at the second pressure-exerting surface 74 as illustrated in FIG. 5) will be less than the diameter of the selected fuel particle being tested (e.g. diameter D.sub.1 of particle 10). Likewise, the diameter D.sub.3 of the second depression 76 will be optimally be equal to the diameter D.sub.2 of the first depression 62. In a preferred embodiment, the diameter D.sub.3 of the second depression 76 will be about 30-60% of the diameter of the fuel particle of interest (e.g. diameter D.sub.1 of particle 10), with an exemplary diameter D.sub.3 range being about 60-600 .mu.m. As a result, the second depression 76 is sized to allow only part of the hemispherical lower portion 14 of fuel particle 10 therein (e.g. within the internal cavity 80) while preventing entry of all of the lower portion 14 into the second depression 76. Furthermore, it is preferred that the length (e.g. depth) L.sub.2 of the second depression 76 (FIG. 5) be less than the diameter of the selected fuel particle (e.g. diameter D.sub.1 of particle 10) and equal to the length (depth) L.sub.1 of the first depression 62. These design features are of substantial importance in the present invention as discussed below. With reference to FIG. 5, the upper and lower compression members 52, 70 are positioned within the testing apparatus 50 so that they are precisely parallel to and spaced apart from each other. In this manner, the first pressure-exerting surface 60 associated with the upper compression member 52 and the second pressure-exerting surface 74 associated with the lower compression member 70 are parallel to and spaced apart from each other, with the first pressure-exerting surface 52 directly facing the second pressure-exerting surface 74. It is also important that the first depression 62 is directly above and in axial alignment with the second depression 76. The term "axial alignment" as used herein shall involve a geometric relationship in which the longitudinal axis At of the first depression 62 (FIG. 5) is in precise axial alignment with the longitudinal axis A.sub.2 of the second depression 76. In this manner as discussed below, the fuel particle 10 (or any other selected fuel particle) may be precisely aligned within the testing apparatus 50 so that compressive force can be applied to the particle in a uniformly-distributed manner. To apply compressive force to the selected particle (e.g. particle 10), the upper and lower compression members 52, 70 within the testing apparatus 50 are operatively connected to a force delivery system which is schematically illustrated in FIGS. 3-5 at reference number 100. The selected force delivery system 100 is designed to move at least one of the upper compression member 52 and lower compression member 70 toward a test particle (e.g. particle 10) placed between the compression members 52, 70 during a test procedure. For example, when fuel particle 10 (or any other test particle) is positioned between the upper and lower compression members 52, 70 as described below, the selected force delivery system 100 could apply compressive force to the particle 10 in the following ways: (1) movement of the upper compression member 52 downward against the particle 10 with the lower compression member 70 remaining stationary; (2) movement of the lower compression member 70 upward against the particle 10 with the upper compression member 52 remaining stationary; or (3) simultaneous movement of the upper compression member 52 downward and the lower compression member 70 upward with the particle 10 compressed therebetween. In this regard, the present invention shall not be limited to any particular compression mode regarding the testing apparatus 50 and compression members 52, 70. Regarding the type of force delivery system 100 which is suitable for use in the testing apparatus 50, many different commercially-available systems may be employed for this purpose which include mechanical actuator mechanisms for moving at least one of the upper and lower compression members 52, 70 as described above. Likewise, the selected system 100 will include an integral measurement monitoring system for determining the amount of force being applied to the selected particle between the compression members 52, 70 during a test procedure. A representative commercial apparatus having all of these features which may be used as the force delivery system 100 is manufactured by Applied Test Systems, Inc. of Butler Pa. (U.S.A.) under the designation "Series 1101". This system is designed to incorporate the upper and lower compression members 52, 70 therein so that the selected particle (e.g. particle 10) can be compressed in a manner which allows the amount of applied force to be precisely monitored. As a result, force levels necessary to cause fracturing of a test particle can be determined. The commercial system described above (e.g. Series 1101 unit produced by Applied Test Systems, Inc.-[hereinafter "ATS"]) consists of a screw-driven universal-type compression testing apparatus. It is designed to move the upper compression member 52 in a downward direction using a screw-drive system, with the lower compression member 70 remaining in a fixed position. The system has a 1000 lb. capacity with a twin screw drive assembly, manually-adjustable limit switches, automatic overload protection, and an automatic break detector regarding the object being tested. The system is designed to operate so that the upper compression member 52 therein can be moved within a speed range of 0.002-20.0 inches per minute, with a speed accuracy of about .+-.1.0%. The system further includes a universal-type load cell having an accuracy rating of .+-.0.1% of range, or .+-.0.5% of indicated load. The load cell in the system is associated with a microprocessor-based load module having four load ranges, digital display, 0-10 VDC output, peak load recall, and overload protection. Also included in the system is a crosshead displacement display unit which includes an incremental encoder in connection with a resolution of 0.0001 in. over the full range of travel. Ranges within the system include 0.2, 2.0, 10.0, and 20.0 in. full scale. In accordance with these features, the foregoing system is capable of applying a controlled compressive load to test fuel particles and thereafter indicating measuring the amount of compressive force needed to fracture a given particle between the compression members 52, 70. As further described below, the upper compression member 52, the lower compression member 70, and the structural features thereof (e.g. axially-aligned depressions 62, 76) are unique and provide highly accurate test results which are not achieved by prior test methods. Regarding the type of apparatus which may be used as the force delivery system 100, many different commercially-available stress-testing systems can be employed for this purpose other than the specific system listed above. In this regard, the present invention shall not be exclusively limited to any particular system for this purpose. Devices which are suitable for use as the force delivery system 100 (e.g. for controlled movement of the upper compression member 52 and/or lower compression member 70) are conventional in nature and commercially available from many other sources including but not limited to Instron Corporation of Canton, Mass. (U.S.A.); Tinius Olsen Testing Machine Co., Inc. of Willow Grove, Pa. (U.S.A.); United Calibration Corp. of Garden Grove, Calif. (U.S.A.); MTS Systems Corp. of Minneapolis, Minn. (U.S.A.); and W. C. Dillon Corp. of Van Nuys, Calif. (U.S.A.). Accordingly, the force delivery system 100 shall not be limited to the ATS Series 1101 system which is provided for example purposes. Other conventional systems may be used in an equally-effective manner provided that they are capable of moving the upper compression member 52 and/or lower compression member 70 in a controlled manner with the ability to generate and display quantitative force data. Regarding preparation of the first depression 62 and the second depression 76, many different production methods may be employed. In this regard, the present invention shall not be exclusively limited to any particular process for producing the depressions 62, 76 within the upper and lower compression members 52, 70. For example, the depressions 62, 76 may be manually produced using conventional processing techniques including but not limited to drilling and machining using standard industrial equipment. Thereafter, the upper and lower compression members 52, 70 are manually aligned to ensure that the first depression 62 is directly above and in axial alignment with the second depression 76 (e.g. axis A.sub.1 of the first depression 62 is aligned with axis A.sub.2 of the second depression 76 as shown in FIG. 5). In a preferred embodiment as described above, the first depression 62 is optimally placed at the center line C.sub.1 of the upper compression member 52, with the second depression 76 being positioned at the center line C.sub.2 of the lower compression member 70. However, the present invention shall not be limited to this particular configuration. The first and second depressions 62, 76 can be located at any respective position on the upper and lower compression members 52, 70 provided that the depressions 62, 76 are axially aligned when used to test a selected fuel particle (e.g. particle 10). It should also be noted that the present invention shall not be limited to a testing apparatus 50 which includes only a single pair of first and second depressions 62, 76 within the upper compression member 52 and the lower compression member 70. Other systems may be used in which multiple pairs of depressions are employed, provided that each pair includes one depression in the upper compression member 52 which is axially aligned with a corresponding depression in the lower compression member 70. In an alternative embodiment, a highly efficient method is disclosed herein for producing the first and second depressions 62, 76 which avoids manual production processes while enabling precise axial alignment between the first depression 62 and the second depression 76. With reference to FIG. 6, a depression-forming spherical member 104 is provided which comprises a hemispherical upper section 106 and a hemispherical lower section 108, with the lower section 108 being equal in size to the upper section 106. The upper section 106 meets the lower section 108 at the juncture represented in FIG. 6 by dashed line 109. The spherical member 104 has a diameter D.sub.4 as illustrated in FIG. 6 which is optimally less than the diameter of the selected fuel particle or particles to be tested in accordance with the invention (e.g. less than the diameter D.sub.1 of the particle 10). In a preferred embodiment, the diameter D.sub.4 of the spherical member 104 will be about 30-60% less than the diameter of the particle or particles to be tested. Exemplary D.sub.4 diameter values for the spherical member 104 will be about 60-600 .mu.m, although the present invention shall not be limited to this range which is provided for example purposes. A method for producing the first and second depressions 62, 76 within the upper and lower compression members 52, 70 using the spherical member 104 is illustrated in FIGS. 7A-7D. To implement the method of FIGS. 7A-7D, the material used to produce the spherical member 104 should have a hardness level which exceeds the hardness of the upper and lower compression members 52, 70. A higher level of hardness associated with the spherical member 104 is necessary to prevent substantial deformation and/or fracturing of the spherical member 104 when compressed between compression members 52, 70 to produce the depressions 62, 76 as discussed below. In this regard, the composition used to manufacture the spherical member 104 may vary, depending on the materials used to construct the upper and lower compression members 52, 70. In a preferred embodiment wherein the upper and lower compression members 52, 70 are made of Type 304 stainless steel, the spherical member 104 is optimally manufactured from zirconia of a type consisting of 96% zirconia partially stabilized with about 4% yttrium oxide. Other compositions which may be used to produce the spherical member 104 include but are not limited to zirconia partially stabilized with calcia or magnesia, iron carbide, alumina, silicon carbide, or silicon nitride. These materials are suitable for use in connection with the list of compositions described above for producing the upper and lower compression members 52, 70. However, the precise construction materials to be used in producing the spherical member 104 may be determined in accordance with preliminary pilot tests on the particular compositions selected for use in manufacturing the upper and lower compression members 52, 70. To form the first and second depressions 62, 76 in a highly efficient manner, the spherical member 104 is positioned in the testing apparatus 50 and placed between the upper compression member 52 and the lower compression member 70 (FIG. 7A). In a preferred embodiment, the upper section 106 of the spherical member 104 will be directly adjacent to, below, and in substantial alignment with the center line C of the upper compression member 52. Likewise, the lower section 108 of the spherical member 104 will be directly adjacent to, above, and in substantial alignment with the center line C.sub.2 of the lower compression member 70. At all times during production of the first and second depressions 62, 76 (regardless of which method is used), the first pressure-exerting surface 60 of the upper compression member 52 should be maintained in a parallel relationship with the second pressure-exerting surface 74 of the lower compression member 70 to ensure proper formation of the depressions 62, 76. Once the spherical member 104 is properly positioned in the testing apparatus 50 as described above, the force delivery system 100 (FIGS. 3-5) associated with the apparatus 50 is activated. As a result, the spherical member 104 is compressed between the upper and lower compression members 52, 70 as illustrated in FIG. 7B. Compression of the spherical member 104 using the force delivery system 100 to move the compression members 52, 70 may be undertaken by (1) movement of the upper compression member 52 against the spherical member 104 while the lower compression member 70 remains stationary; (2) movement of the lower compression member 70 against the spherical member 104 while the upper compression member 52 remains stationary; or (3) movement of the upper and lower compression members 52, 70 simultaneously against the spherical member 104. The type of compression mode to be selected will depend on the particular force delivery system 100 chosen for use in the present invention. Compression of the spherical member 104 between the upper and lower compression members 52, 70 in the foregoing manner is allowed to continue until the spherical member 104 is pressed inwardly into the compression members 52, 70 as shown in FIG. 7C. As a result, the upper section 106 of the spherical member 104 is pressed into the first pressure-exerting surface 60 and upper compression member 52 to produce the first depression 62. Likewise, the lower section 108 of the spherical member 104 is pressed into the second pressure-exerting surface 74 and lower compression member 70 to produce the second depression 76. Formation of the first and second depressions 62, 76 in this manner is accomplished by the greater hardness level of the spherical member 104 compared with the upper and lower compression members 52, 70. Furthermore, this method may be used to produce first and second depressions 62, 76 of a different size (e.g. depth) as may be desired for particular applications in connection with specific fuel particles of interest. To produce first and second depressions 62, 76 of a particular depth (e.g. L and L.sub.2 as shown in FIG. 5), compression of the spherical member 104 illustrated in FIGS. 7B-7C is allowed to continue until depressions of the desired configuration (depth) are achieved. In the embodiment of FIG. 7 (and in most embodiments of concern) the compression process can be allowed to continue until the upper compression member 52 meets (e.g. substantially contacts) the lower compression member 70 (FIG. 7C). However, variable degrees of compression and displacement of the upper and lower compression members 52, 70 can be used to produce depressions 62, 76 of different size and depth as desired. In a preferred embodiment involving the materials recited herein (e.g. a zirconia spherical member 104, stainless steel upper and lower compression members 52, 70, as well as the other compositions/components described above), production of the depressions 62, 76 will involve the application of about 448-1779N of force to the spherical member 104. However, exact production parameters will depend on the particular materials being used within the testing apparatus 50 (e.g. the type of spherical member 104) and the size of the fuel particle to be tested. In this regard, the present invention shall not be limited regarding the exemplary embodiment shown in FIGS. 7A-7D. The final step associated with the depression-forming process involves separation of the upper and lower compression members 52, 70 from each other within the testing apparatus 50 and removal of the spherical member 104 therefrom (FIG. 7D). As a result, the first and second depressions 62, 76 may be formed in a highly efficient manner with a precise degree of axial alignment. These results are rapidly achieved using a minimal amount of equipment while avoiding manual alignment procedures. It should likewise be noted that, if desired, multiple pairs of depressions may be formed in the foregoing manner by using more than one spherical member 104 during the compression process (e.g. one spherical member 104 for each pair of depressions in the upper and lower compression members 52, 70). Having formed the first depression 62 and second depression 76 within the upper and lower compression members 52, 70, testing of the selected fuel particle (e.g. particle 10) may now be undertaken. While the present invention is applicable in connection with a wide variety of different fuel particles and compositions, the process described below shall be presented relative to particle 10 for example purposes. With reference to FIGS. 8A-8C, the testing method of the present invention is schematically illustrated. As shown in FIG. 8A, the particle 10 is initially placed within the testing apparatus 50 between the upper and lower compression members 52, 70. At this point during the testing process, the upper and lower compression members 52, 70 are spaced apart from each other in a amount sufficient to permit placement of the particle 10 therebetween (e.g. an amount in excess of the diameter D associated with the particle 10). To avoid the introduction of any extraneous structural defects in the particle 10 prior to testing, it is handled carefully with a minimal amount of physical manipulation. In certain cases as determined by preliminary pilot studies on the fuel particles of interest, layers of material surrounding the barrier layer in the test particle may be removed thermally (e.g. by burning) or through the use of chemical etchants. For example, regarding particle 10, the outer protective layer 30 and external coating 32 which are both comprised of carbon could be removed by burning in a conventional furnace at a temperature of about 900.degree. C. to expose the underlying barrier layer 22 (made of SIC). Thereafter, any oxidized materials which remain on the barrier layer 22 could be removed using a chemical etchant (e.g. hydrofluoric acid). However, the present invention shall not be limited to any particle configuration, and shall not be dependent on the presence or absence of material layers which cover the barrier layer in a test particle. The barrier layer in the selected test particle (e.g. layer 22 in particle 10) is responsible for a predominant portion of the strength and structural integrity associated with the particle. In many cases, the removal of layers covering the barrier layer 22 will provide a more direct placement of the designated load on the barrier layer 22, thereby facilitating a more direct calculation of stress values. However, a determination regarding the removal of layers covering the barrier layer 22 will depend on a variety of factors as indicated by preliminary pilot testing. As illustrated in FIG. 8A, the particle 10 is placed within the testing apparatus 50 so that the upper portion 12 thereof is aligned with and directly below the first depression 62 in the upper compression member 52, with the lower portion 14 of particle 10 being aligned with and directly above the second depression 76 in the lower compression member 70. Thereafter, at least one of the upper compression member 52 and the lower compression member 70 is moved toward and against the particle 10 by the force delivery system 100 so that the compression members 52, 70 are positioned as illustrated in FIG. 8B. As previously indicated, placement of the particle 10 in the position shown in FIG. 8B and subsequent compression of the particle 10 is accomplished by (1) movement of the upper compression member 52 toward and against the particle 10 in a downwardly direction with the lower compression member 70 remaining in a stationary position; (2) movement of the lower compression member 70 toward and against the particle 10 in an upward direction with the upper compression member 52 remaining in a stationary position; or (3) movement of the upper compression member 52 and lower compression member 70 simultaneously toward and against the particle 10. The exact mode of compression to be employed will depend on the type of force delivery system 100 selected for use in any given case, with the present invention not being limited to any particular force delivery system 100 or compression mode. As illustrated in FIG. 8B, the particle 10 is firmly maintained in position between the upper compression member 52 and the lower compression member 70. Specifically, part of the upper portion 12 of the particle 10 (e.g. section 120 in FIG. 8B above dashed line 122) is positioned within the upper depression 62. Accordingly, section 120 of the particle 10 is located within the internal cavity 64 of the first depression 62 and beneath the first pressure-exerting surface 60. The remainder of the upper portion 12 of particle 10 is located outside of the depression 62 and within gap 130 between the upper compression member 52 and lower compression member 70 (FIG. 8B). As a result, entry of the entire upper portion 12 into the first depression 62 is prevented, with the upper portion 12 being only partially positioned within the first depression 62. Likewise, part of the lower portion 14 of the particle 10 (e.g. section 132 in FIG. 8B below dashed line 140) is positioned within the lower depression 76. In this manner, section 132 of the particle 10 is located within the internal cavity 80 of the second depression 76 and beneath the second pressure-exerting surface 74. The remainder of the lower portion 14 of particle 10 is located outside of the depression 76 and within gap 130 between the upper and lower compression members 52, 70. Once again, entry of the entire lower portion 14 into the second depression 76 is prevented as illustrated in FIG. 8B, with the lower portion 14 being only partially positioned within the second depression 76. This configuration provides numerous benefits compared with other stress application systems (e.g. those which do not use the dual depressions of the present invention and instead involve planar structures which apply force at discrete (single) points on the particle of interest). In particular, the method of the present invention enables a broader distribution of compressive forces and a resultant broad distribution of maximum tensile stresses within the barrier layer of each particle being tested, thereby providing more accurate results and greater detection of widely-dispersed defects. The depression-based system described herein also prevents axial, lateral, and rotational slippage of the particle being tested compared with point-type compression systems. This factor likewise contributes to improved accuracy and testing efficiency. Next, as illustrated in FIG. 8C, compressive force is applied to the particle 10 by movement of at least one of the upper compression member 52 and lower compression member 70 against the particle 10 as described above. This process in undertaken by the force delivery system 100 in a conventional manner as previously indicated. During compression of the particle 10, the circular rim portion 69 associated with the upper compression member 52 (which is formed at the juncture between the first pressure-exerting surface 60 and side wall 66 of depression 62) forcibly engages the upper portion 12 of the particle 10. As a result, compressive force is broadly applied to the upper portion 12 of the particle 10 in a circular pattern which circumferentially surrounds the particle 10 as illustrated in FIG. 1 at curved dashed line 146. In certain cases which depend on the character of the particle 10 being tested (as well as the type of upper compression member 52 being used), the particle 10 and/or rim portion 69 may actually deform in a slight manner prior to fracturing of the particle 10 as force is applied thereto. Accordingly, the circular force pattern applied to the upper portion 12 of the particle 10 may be somewhat broader and more spread out (widely distributed) than the discrete application of force schematically illustrated at single dashed line 146 in FIG. 1. Regardless of whether this phenomenon occurs, the force pattern applied to the upper portion 12 of the particle 10 in accordance with the invention will provide all of the unique benefits previously described and further discussed below. During compression of the particle 10, the circular rim portion 84 associated with the lower compression member 70 (which is formed at the juncture between the second pressure-exerting surface 74 and side wall 82 of depression 76) forcibly engages the lower portion 14 of the particle 10. Accordingly, compressive force is broadly applied to the lower portion 14 of the particle 10 in a circular pattern which circumferentially surrounds the particle 10 as illustrated in FIG. 1 at curved dashed line 150. In certain cases which again depend on the character of the particle 10 being tested (as well as the type of lower compression member 70 being used), the particle 10 and/or rim portion 84 may actually deform in a slight manner prior to fracturing of the particle 10 as force is applied thereto. As a result, the circular force pattern applied to the lower portion 14 of the particle 10 may be somewhat broader and more spread out (widely distributed) than the discrete application of force schematically illustrated at single dashed line 150 in FIG. 1. Regardless of whether this phenomenon occurs, the force pattern applied to the lower portion 14 of the particle 10 will provide all of the unique benefits previously described and further discussed below. Compression of the particle 10 in the foregoing manner continues at a gradual rate until fracturing takes place. Regardless whether the upper compression member 52, the lower compression member 70, or both move against the particle 10, movement of these components is undertaken at a preferred rate of about 0.002-0.004 inches minute. As soon as the particle 10 reaches its maximum stress capacity, it fractures into multiple fragments 152 illustrated schematically in FIG. 8C. Immediately upon fracturing in this manner, the application of compressive force (e.g. movement of the upper compression member 52 and/or lower compression member 70) within the testing apparatus 50 is stopped either manually or automatically, depending on the type of commercial force delivery system 100 being used. When fracturing occurs, the force value necessary to fracture the particle 10 (typically in Newtons) is obtained measured from the force delivery system 100 which integrally includes a monitoring sub-system 160 designed to display the force value of concern. Such a monitoring sub-system 160 is a standard component of commercially available force delivery systems which are suitable for use in the present invention as discussed above (including the ATS Series 1101 system previously described). At this point, the testing process is completed. The fragments 152 can thereafter be viewed using scanning electron microscopy for detailed observation of fracture patterns and identification of metallic inclusions therein. Chemical analysis of the fragments 152 can also be undertaken using many techniques including but not limited to electron dispersive spectroscopy (EDS) to provide additional information regarding the test particles and defects associated with the particles. The resulting force data can then be interpreted, manipulated, plotted, statistically configured, and otherwise used in many different conventional ways as desired. In this regard, the present invention shall not be limited to any particular use or treatment of data received using the foregoing process. Further information regarding data interpretation will be discussed below. C. Benefits and Advantages--Data Manipulation The present invention which involves placement of the selected fuel particle within first and second depressions 62, 76 in the upper and lower compression members 52, 70 provides numerous benefits compared with "point-type" compression systems and "ring-type" systems described above. The method disclosed herein enables the testing of whole fuel particles without dissecting and removing portions of the particles to be tested. As a result, the possibility of introducing additional defects into the particles prior to testing is avoided. Also, the present invention may test particles in a highly rapid manner without undesired axial, rotational, or lateral movement of the particles between the compression members within the testing apparatus. Furthermore, engagement of the selected particles within the testing apparatus is undertaken without the need for adhesives or other chemical fixatives. Because the method of the present invention enables testing in a rapid and efficient manner without the need for extensive manual alignment procedures, strength statistics can be rapidly gathered on hundreds of particles so that failure probabilities at low stresses may be measured with a minimum amount of extrapolation. Finally, and of considerable importance compared with point-type testing systems, the method described herein provides a wide distribution of the contact load through the surface and interior volume of the barrier (e.g. SiC) layer in each test particle so that strength statistics reflect a combination of both surface and volume flaws. Compared with point-type tests, the present invention is characterized by a much higher probability of flaw detection due to broader exposure of the particles (and barrier layers therein) to high stress levels. For these reasons, the method of the present invention represents a significant advance in the art of nuclear fuel particle testing, especially in connection with multi-layer particles of the type described above. The data obtained using the foregoing process may be manipulated and interpreted in many different ways. For example, the compressive force needed to fracture the test particle can be mathematically converted to a tensile strength (stress) value. This is accomplished through the use of commercial finite element computer software packages (e.g. products sold under the name "ABAQUS" (version 4.9) by Hibbett, Karlsson, & Sorenson of Providence, R.I. (U.S.A.) and "PATRAN" (version 2.4) by PDA Engineering of Costa Mesa, Calif. (U.S.A.). Furthermore, the probability that a given fuel particle out of a group of particles will fracture can be calculated by the proper application of "weakest link statistics" as discussed in Quinn, G. D., "Strength and Proof Testing", Engineering Materials Handbook, Vol. 4, p. 585-598, ASM International (1991) which is incorporated herein by reference. One specific functional form (mathematical expression of probability of failure as a function of strength) that can be used to represent these statistics involves a process conventionally known as "Weibull Statistical Analysis". Weibull techniques and expressions suitable for interpreting force data in accordance with the invention, as well as other information involving stress analysis in ceramic materials, are discussed and outlined in Trustrum, A. G., et al., "Applicability of Weibull Analysis for Brittle Materials", J. Mater. Sci., 18:2765-2770 (1983); Richerson, D. W., Modern Ceramic Engineering, Marcel Dekker, Inc., New York, Ch. 15, pp. 662-679 (1982); and Evans, A. G., Fracture in Ceramic Materials, Noyes Publications, Park Ridge, N.J., Ch. 15, pp. 364-402 (1984), all of which are incorporated herein by reference. Regardless of which mathematical expression is used during curve fitting procedures, a large number of samples (fuel particles) should be tested to achieve accurate estimates of failure probabilities at low stress levels. The testing of about 500-1000 particles in any given situation will provide adequate results. The use of substantial numbers of test particles produces data for very weak particles in the test group and therefore minimizes extrapolation of the data curves to low probabilities. Testing a large number of particles will also indicate whether there is a small population of particular flaws which are more harmful to overall strength and structural integrity levels compared with the majority of more common flaws. Evidence of different flaw populations can be demonstrated by a group of data points with a different slope on a Weibull plot involving the following expression: In ln[1/1-probability of failure]v. ln of strength. Particular evidence of different flaw populations often becomes obvious as a "dog leg" configuration to the left within the foregoing plot at low strength levels or to the right at high strength levels. If an insufficient number of tests are made, mean strength values can be extrapolated by using a straight line into the low-strength region of the plot. There are numerous methods, approaches, and techniques for interpreting data generated from the compression testing process of the present invention. In this regard, the invention shall not be limited to any statistical methods in connection with data generated as described above. The present invention represents an advance in the art of nuclear fuel testing, and solves numerous problems uniquely associated with the testing of fuel particles. Having herein described preferred embodiments of the invention, it is anticipated that suitable modifications may be made thereto by individuals skilled in the relevant art which nonetheless remain within the scope of the invention. The present invention shall therefore only be construed in accordance with the following claims:
	claims	1. A method of aligning an alignment layer for a liquid crystal display device, comprising:forming an alignment layer on a substrate such that the alignment layer has side chains protruding from a surface of the alignment layer;positioning the substrate with alignment layer on a stage of an ion beam irradiating apparatus;forming a non-altered area in the alignment layer by switching OFF an ion generator while one of the stage and ion generator is moving; andforming an ion-altered area in the alignment layer by switching ON the ion generator while the one of the stage and ion generator is stopped. 2. The method of aligning an alignment layer for a liquid crystal display device according to claim 1, further comprising:forming another ion-altered area in the alignment layer by switching ON the ion generator while the one of the stage and the ion generator is stopped again such that the non-altered area is disposed between two adjacent ion-altered areas. 3. The method of aligning an alignment layer for a liquid crystal display device according to claim 1, wherein the substrate is one of the array substrate and the color filter substrate. 4. The method of aligning an alignment layer for a liquid crystal display device according to claim 1, wherein the forming the ion-altered area in the alignment layer alters the side chains. 5. A method of aligning an alignment layer for a liquid crystal display device, comprising:forming an alignment layer on a substrate such that the alignment layer has side chains protruding from a surface of the alignment layer;positioning the substrate with alignment layer on a stage of an ion beam irradiating apparatus;forming an ion-altered area in the alignment layer by stopping one of the stage and ion generator while an ion generator is turned ON in a first interval; andforming a non-altered area in the alignment layer by moving one of the stage and ion generator while the ion generator is turned ON in a second interval shorter than the first interval. 6. The method of aligning an alignment layer for a liquid crystal display device according to claim 5, further comprising:forming another ion-altered area in the alignment layer by switching ON the ion generator while the one of the stage and ion generator is stopped again such that the non-altered area is disposed between two adjacent ion-altered areas. 7. The method of aligning an alignment layer for a liquid crystal display device according to claim 5, wherein the substrate is one of the array substrate and the color filter substrate. 8. The method of aligning an alignment layer for a liquid crystal display device according to claim 5, wherein the forming an ion-altered area in the alignment layer alters the side chains. 9. A liquid crystal display device, comprising:a first substrate having a black matrix, a color filter layer and a common electrode;a second substrate having gate lines, data lines and thin film transistors connected to pixel electrodes;a first alignment layer on the first substrate;a second alignment layer on the second substrate; anda liquid crystal layer having a plurality of liquid crystal molecules and positioned between the first and second alignment layers,wherein each of the first and second alignment layers has a first area with ion-altered side chains and a second area with non-altered side chains,wherein the liquid crystal molecules include first liquid crystal molecules having a first pre-tilt angle with respect to one of the first and second alignment layers in a clockwise direction, second liquid crystal molecules having a second pre-tilt angle with respect to the one of the first and second alignment layers in the clockwise direction, and third liquid crystal molecules having a third pre-tilt angle, which is smaller than the first pre-tilt angle and greater than the second pre-tilt angle, with respect to the one of the first and second alignment layers in the clockwise direction,wherein the first and second liquid crystal molecules are adjacent to the one of the first and second alignment layers, and the third liquid crystal molecules are adjacent to the first and second liquid crystal molecules,wherein the first liquid crystal molecules and the second liquid crystal molecules are alternately and horizontally arranged with each other in each pixel region,wherein the liquid crystal molecules further include fourth liquid crystal molecules having a fourth pre-tilt angle with respect to the other one of the first and second alignment layers in the clockwise direction, fifth liquid crystal molecules having a fifth pre-tilt angle with respect to the other one of the first and second alignment layers in the clockwise direction, and sixth liquid crystal molecules having a sixth pre-tilt angle, which is smaller than the fourth pre-tilt angle and greater than the fifth pre-tilt angle, with respect to the other one of the first and second alignment layers in the clockwise direction, andwherein the fourth and fifth liquid crystal molecules are adjacent to the other one of the first and second alignment layers, and the sixth liquid crystal molecules are adjacent to the fourth and fifth liquid crystal molecules. 10. The liquid crystal display device according to claim 9, wherein the first and second alignment layers are a vertical type. 11. The liquid crystal display device according to claim 9, wherein the first and second alignment layers have a plurality of first and second areas, and the first and second areas are alternately disposed with each other. 12. The liquid crystal display device according to claim 9, wherein the first and second alignment layers have a plurality of first and second areas, and the first areas have a different width than the second areas. 13. The liquid crystal display device according to claim 9, wherein the liquid crystal layer contains more third liquid crystal molecules than either second liquid crystal molecules or first liquid crystal molecules. 14. A liquid crystal display device, comprising:a first substrate having a black matrix, a color filter layer and a common electrode;a second substrate having gate lines, data lines and thin film transistors connected to pixel electrodes;a first alignment layer on the first substrate;a second alignment layer on the second substrate; anda liquid crystal layer of liquid crystal molecules positioned between the first and second alignment layers,wherein the liquid crystal molecules include first liquid crystal molecules having a first pre-tilt angle with respect to one of the first and second alignment layers in a clockwise direction, second liquid crystal molecules having a second pre-tilt angle with respect to the one of the first and second alignment layers in the clockwise direction, and third liquid crystal molecules having a third pre-tilt angle, which is smaller than the first pre-tilt angle and greater than the second pre-tilt angle, with respect to the one of the first and second alignment layers in the clockwise direction,wherein the first and second liquid crystal molecules are adjacent to the one of the first and second alignment layers, and the third liquid crystal molecules are adjacent to the first and second liquid crystal molecules,wherein the first liquid crystal molecules and the second liquid crystal molecules are alternately and horizontally arranged with each other in each pixel region,wherein the liquid crystal molecules further include fourth liquid crystal molecules having a fourth pre-tilt angle with respect to the other one of the first and second alignment layers in the clockwise direction, fifth liquid crystal molecules having a fifth pre-tilt angle with respect to the other one of the first and second alignment layers in the clockwise direction, and sixth liquid crystal molecules having a sixth pre-tilt angle, which is smaller than the fourth pre-tilt angle and greater than the fifth pre-tilt angle, with respect to the other one of the first and second alignment layers in the clockwise direction, andwherein the fourth and fifth liquid crystal molecules are adjacent to the other one of the first and second alignment layers, and the sixth liquid crystal molecules are adjacent to the fourth and fifth liquid crystal molecules. 15. The liquid crystal display device according to claim 14, wherein the first liquid crystal molecules correspond to first areas of the first and second alignment layers and the second liquid crystal molecules correspond to second areas of the first and second alignment layers. 16. The liquid crystal display device according to claim 15, wherein the first areas have a different width than the second areas. 17. The liquid crystal display device according to claim 15, wherein the first and second areas are alternately disposed with each other. 18. The liquid crystal display device according to claim 14, wherein the first pre-tilt angle is about 0 degree, the second pre-tilt angle is about 90 degrees, and the third pre-tilt angle is in a range of about 20 to 70 degrees such that the liquid crystal molecules in the liquid crystal layer are arranged into a bend-I state of an optically compensated bend mode for the liquid crystal display device. 19. The liquid crystal display device according to claim 14, wherein the liquid crystal layer has an average pre-tilt angle of about 20 to 70 degrees.
	abstract	A method of forming a fuel rod for a nuclear reactor comprises disposing a powder comprising particles of a fuel material on a substrate, exposing the powder to energy from an energy source to form a first layer of a nuclear fuel, the first layer comprising inter-granular bonds between the particles of the fuel material, disposing additional powder comprising particles of the fuel material over the first layer of the nuclear fuel, and exposing the additional powder to energy from the energy source to form a second layer of the nuclear fuel and to form the nuclear fuel to have a void fraction greater than about 0.20, the second layer comprising inter-granular bonds between the additional powder and the first layer of the nuclear fuel. Related nuclear fuels comprising a porous structure, fuel rods, nuclear reactors, and methods are disclosed.
050911406	summary	BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is generally related to nuclear system pressurizers and in particular to the heater sleeves in the pressurizers. 2. General Background The pressurizer in a nuclear reactor coolant system establishes and maintains the reactor coolant system pressure within the prescribed limits of the system. It provides a steam surge chamber and a water reserve to accommodate reactor coolant density changes during operation. A typical pressurizer is a vertical, cylindrical vessel with replaceable electric heaters in its lower section. The electric heaters are positioned below the normal water line and are actuated to restore normal operating pressure when the pressure in the reactor coolant system has decreased. The electric heaters are comprised of a plurality of heating elements that extend through nozzles or sleeves through the wall of the pressurizer. Support plates inside the pressurizer are provided with holes in coaxial alignment with the holes in the pressurizer wall and the nozzles for receiving and supporting the heating elements. The nozzles extend outward from the pressurizer to provide exterior support to the heating elements. Due to the operating environment, it is a common requirement that heating elements and the nozzles through which they extend the replaced. Because alignment between the support plate holes and the nozzle is critical, it has previously been required that the replacement nozzle be fabricated to original design dimensional specifications and installed into the original bore in the pressurizer wall to insure proper alignment of the nozzle inner diameter with the corresponding support plate hole after welding. This process required that the removal of the original nozzle weld and installation of the repair weld be performed from inside the pressurizer because the bore through the pressurizer could not be enlarged for tooling access without potentially altering the alignment of the heater penetration with respect to the holes in the support plates. Since pressurizer components in nuclear power plants become radioactive after they have been in operation, performing such work inside the pressurizer is difficult and hazardous to personnel and thus impractical. What is needed is a means of replacing the heating element and nozzle without the need for personnel to enter a radioactive pressurizer. SUMMARY OF THE INVENTION The present invention solves the above problem in a straightforward manner. What is provided is a two piece pressurizer heater sleeve. After the original nozzle is removed the bore in the pressurizer wall is enlarged in diameter to remove degraded material. An outer sleeve machined for a shrink fit is installed in the enlarged bore. The outer sleeve is structurally welded to the pressurizer outer diameter and seal welded to the pressurizer inner diameter cladding. The inner diameter of the outer sleeve is machined to match that of the original bore to maintain the proper alignment. An inner sleeve sized to fit within the outer sleeve is installed therein and extended into the pressurizer beyond the end of the outer sleeve. The inner sleeve is structurally welded to the outer sleeve on the outside of the pressurizer. The inner diameter of the inner sleeve matches that of the original nozzle once installed so that the heating element may be readily installed and is aligned with holes in the support plate.
	summary
	description	According to the present invention, there are provided a novel class of debond coated non-oxide ceramic reinforcing fibers comprising a non-oxide continuous ceramic fiber, preferably carbon fiber or silicon carbide fiber, preferably, but not necessarily, first surface coated with a layer of pyrolytic carbon and then overcoated with one or more layers of a non-hygroscopic, oxidation resistant, protective material. According to various preferred embodiments of the instant invention, the non-hygroscopic oxidation resistant, protective layer(s) may comprise a monolithic layer of Ti3SiC2, Ti5Si3, TiSi2, or TiSi, one or more layers of SiC/TiC or the oxidation product thereof, or one or more layers of SiO2/TiO2. Referring now to FIG. 1 that depicts a cross-sectional view, according a first preferred embodiment of the present invention, the enhanced continuous reinforcing fiber of the present invention 10 comprises a continuous, non-oxide fiber core 12 having a thin, from about 0.1 xcexcm to about 0.2 xcexcm, layer 14 of pyrolytic carbon annularly applied about the surface thereof and a layer 16 of a non-hygroscopic, oxidation resistant material annularly applied thereover. In the embodiment depicted in FIG. 1, layer 16 is preferably Ti3SiC2 that is applied as described hereinafter. FIG. 2 depicts an alternative preferred embodiment wherein non-hygroscopic, oxidation resistant layer 16 is applied annularly directly over the surface of continuous, non-oxide core 12 with no pyrolytic carbon layer 14 therebetween. In the description and examples that follow, reference will be made to and description will be provided primarily of embodiments of the present invention that include pyrolytic carbon layer 14 as part of the structure or as a step in the fabrication process. It should be specifically noted that all such structures and the processes for preparing them can be identically prepared and performed without the presence of the pyrolytic carbon layer and both such structures and methods for their preparation are clearly intended and contemplated as within the scope of the appended claims and the herein described invention. An alternate preferred embodiment of the present invention is depicted in FIG. 2. According to this embodiment, the debond coated reinforcing fiber 10 comprises a non-oxide continuous fiber core 12 having a similarly thin layer 14 of pyrolytic carbon about the surface thereof and a pair of non-hygroscopic, oxidation resistant layers 18 and 20 applied sequentially thereover as described hereinafter. According to a specifically preferred embodiment of the present invention, layers 18 and 20 are SiC and TiC, respectively. In an alternate preferred embodiment, the sequentially applied SiC and TiC layers are oxidized to SiO2 and TiO2. Oxidation resistant layers 18 and 20 can, of course, be coated directly over the surface of fiber core 12. In the third alternative preferred embodiment of the present invention depicted in cross section in FIG. 3, the debond coated reinforcing fiber 10 of the present invention comprises a continuous fiber core 12 having a similarly thin layer of pyrolytic carbon 14 applied annularly thereabout that is subsequently coated as described hereinafter with alternating layers 22, 24, 26 and 28 that are respectively either SiC and TiC, or SiO2 and TiO2. This structure may be expanded to include a further plurality of such alternating layers. Again, alternating layers 22, 24, 26, and 28 can be coated directly onto the surface of fiber core 12 in the absence of pyrolytic carbon layer 14. In each of the foregoing structures, the thickness of the pyrolytic carbon layer, when present, is preferably between about 0.1 xcexcm and about 0.2 xcexcm. Each of the other non-hygroscopic, oxidation resistant layers 16 through 28 and any additional protective layers are preferably between about 0.2 xcexcm and about 0.5 xcexcm thick in total, although thicker layers may of course be used in those applications where layer thickness does not affect the functionality of the coatings in the final composite structure. For example, the entire matrix could consist of a multi-layer structure. While not wishing to be bound in any way by any specific mechanism that describes the effectiveness or functional operation of the improved reinforcing fibers described and claimed herein, it is postulated from the TiO2xe2x80x94SiO2 phase diagram that on oxidation of fibers with or without an inner carbon layer at the surface and one of the protective layers described herein coated thereover separate SiO2 and TiO2 layers are formed. TiO2 is known to be a lubricious, low shear strength oxide that is ideal for an interface coating and that SiO2 will provide oxidation resistance for both carbon and silicon carbide fibers. The effect of adsorbed water in these coatings appears to be negligible at temperatures of 700xc2x0 C. and above. The immiscibility of these two materials even at temperatures up to about 1550xc2x0 C. provides that they will each retain their inherent lubricious and antioxidant characteristics even at these temperatures. Hence, since TiO2 and SiO2 are the oxidation products of titanium suicides (TixSiy), Ti3SiC2 and SiC/TiC layers of these materials, upon oxidative attack they will provide SiO2 and TiO2 that will impart their respective needed properties to the reinforcing fiber at temperatures well in excess of 1200xc2x0 C. The preferred methods for the application of the non-hygroscopic, oxidation resistant coatings of the present invention to continuous non-oxide reinforcing fibers to yield the improved fibers of the present invention are presented schematically in FIGS. 4 and 5. Referring now to FIG. 5, the continuous non-oxide reinforcing fiber is first, preferably, coated with a thin layer of pyrolytic carbon preferably applied by chemical vapor deposition (CVD) or chemical vapor infiltration (CVI) depending upon whether the fiber to be coated is in the form of a single fiber, fiber cloth or a preform shape. Deposition is accomplished by placement of the fiber, fiber cloth or preform into an appropriate reaction chamber of the type well known in the art and decomposing, for example, CH4 or C3H8 at temperatures between about 1000 and 1300xc2x0 C. and pressures of 10 Torr or less. This procedure is common to all of the fabrication processes described herein that apply pyrolytic carbon layer 14 regardless of the nature of the coatings(s) applied over pyrolytic carbon layer 14. Selection of the pyrolytic coating process as with all of the other coating processes described hereinafter will depend largely upon the form of the fiber being coated, i.e. whether it is in the form of a single continuous fiber, a fiber cloth (tow) or a preform. CVD coating is preferred for single fiber or fiber tow coating while CVI is preferred for coating of fibers as a preform. In the case of the formation of the single phase Ti3SiC2 coatings described hereinabove, coating is accomplished through the introduction of: 1) the continuous fiber, cloth or preform along with; 2) SiCl4, TiCl4, and CCl4 in relative concentrations according to the following reaction: 3TiCl+SiCl4+3CCl4, (as specified further below) and 3) hydrogen and or hydrogen and argon as a carrier gas, into a suitable reaction chamber. Reaction is accomplished within the temperature range of from about 1000xc2x0 C. and about 1600xc2x0 C., preferably between about 1100xc2x0 and about 1400xc2x0 C. and most preferably between about 1100xc2x0 C. and about 1200xc2x0 C., at a pressure preferably below about 760 Torr, more preferably below about 400 Torr and most preferably below about 250 Torr and preferably for a period of from about 3 to about 240 minutes, more preferably from about 6 to about 60 minutes and most preferably from about 9 to about 30 minutes or until a thickness of from about 0.2 to about 0.5 xcexcm of Ti3SiC2 has been deposited on the fibers. The carrier gas preferably comprises from about 32% to about 99% by weight hydrogen and from about 0% to about 69% by weight of argon, more preferably from about 48 to about 98% by weight of hydrogen and from about 0 to about 50% by weight of argon and most preferably from about 58 to about 98% by weight of hydrogen and from about 10 to about 40% by weight of argon. TiCl4 is introduced preferably at a concentration of between about 0.06% and about 18% by weight, more preferably between about 0.2% and about 3% by weight and most preferably between about 0.4% by weight and about 2.2% by weight. SiCl4 is preferably introduced at a concentration of between about 0.04% by weight and about 16% by weight, more preferably between about 0.15% and about 1.4% by weight and most preferably between about 0.2% and about 1.2% by weight. The concentration of CCl4 introduced preferably ranges from about 0.02% to about 8% by weight, more preferably between about 0.15% and about 1.4% by weight and most preferably between about 0.2% and about 1.2% by weight. The deposited Ti3SiC2 coating may then optionally be converted to produce in situ a dual phase coating of SiO2/TiO2 by heating the coated fiber structure at a temperature of from about 1000xc2x0 C. to about 1600xc2x0 C. for a period of from about 1 minute to about 120 minutes. Most preferably, oxidation is accomplished by heating in air at a temperature of between about 1300xc2x0 C. and about 1400xc2x0 C. for a period of from about 10 minutes to about 20 minutes. As noted hereinabove, a similar process can be performed to provide the debond coatings of the present invention directly on the surface of fiber core 12 in the absence of any pyrolytic carbon layer 14 by the omission of the carbon application step. The titanium silicide (TixSi5 wherein x=1 or 5 and y=1,2, or 3) layers(s) that can be subsequently oxidized according to the procedures described hereinabove are formed by the reaction between TiCl4 and SiCl4 described immediately hereinabove, but in the absence of the carbon contributing CCl4. Referring now to FIG. 6, the two layered coatings of SiC/TiC are formed by first forming the pyrolytic coating on the fibers either as individual fibers, fiber cloth or a preform as described above, and then sequentially forming layers of SiC and TiC thereover through CVD) or CVI (depending upon the form of the fiber i.e. continuous single fiber, fiber cloth or preform) by: A) decomposing trichloromethyl silane (CH3SiCl3) with hydrogen or hydrogen and argon as a carrier gas at a temperature of from about 800xc2x0 C. to about 1600xc2x0 C. and a pressure of from about 0 Torr to about 760 Torr for a period of from about 3 minutes to about 240 minutes and then B) reacting TiCl4 with C3H8 in a concentration of from about 0.08% to about 1.5% TiCl4 in C3H8 at a temperature of from about 1000xc2x0 C. to about 1600xc2x0 C. and a pressure of from about 0 Torr to about 760 Torr for a period of from about 15 seconds to about 30 minutes. The layered coating will consist of alternating 0.3 xcexcm layers of SiC and TiC for a total coating thickness of 0.4 xcexcm. Optionally, the coated ceramic fibers, cloth or preform may then be oxidized in air at a temperature as described hereinabove to produce a single layered SiO2/TiO2 structure prior to further processing. The identical process may, of course be performed in the absence of the pyrolytic carbon application step to obtain an equally useful product. Referring now to FIG. 7, multi-layered SiO2/TiO2 structures may be produced by first applying the pyrolytic coating as described hereinabove to the ceramic reinforcing fiber, and then repeating the process described in connection with FIG. 6 several times, each time building alternating SiC/TiC layers only 0.05 xcexcm thick to a total coating thickness of 0.5 xcexcm. Oxidation of the coated ceramic fibers, cloth or preform by heating in air as described hereinabove yields a multi-layered SiO2/TiO2 structure prior to further processing. Again, the application of the pyrolytic carbon layer may be omitted to obtain a similarly useful product. Coatings of TiC and SiC may also be applied according the procedures and under the reaction conditions described immediately hereinafter for the production of SiO2/TiO2 coatings, except that the carrier gas contains no water or CO2. Two layered and multi-layer oxide coatings can also be produced by sequential application of SiO2 and TiO2 over pyrolytic carbon layer 14 or directly to fiber core 12 as described hereinabove but in a hydrogen or hydrogen and argon plus CO2 and water atmosphere comprised of from about 32% to about 99% by weight hydrogen, from about 0 to about 60% by weight argon, from about 0% to about 32% by weight of water and from about 0 to about 16% by weight of CO2 at a temperature of from about 1000xc2x0 C. to about 1600xc2x0 C. and a pressure below about 760 Torr for a period of from about 15 minutes up to about 120 minutes. It is preferred that the reaction be performed at a temperature of between about 1100xc2x0 C. and about 1400xc2x0 C. for a period of from about 15 seconds up to about 30 minutes and at a pressure below about 400 Torr. Most preferably the reaction conditions are at a temperature of between about 1200xc2x0 C. and about 1300xc2x0 C. for a period of from about 1 to about 15 minutes and at a pressure below about 250 Torr. The concentrations of TiO2 and SiO2 preferably range from about 0.08% and about 16% by weight, more preferably these concentrations range from about 0.12% and about 2.7% by weight and most preferably between about 0.18% and about 1.5% by weight. The layered coatings consists of alternating 0.2 xcexcm layers of SiO2 and TiO2 and 0.05 xcexcm layers of SiO2 and TiO2 to a total coating thickness of 0.4 xcexcm. As will be apparent to the skilled artisan, although CVD and CVI processes are preferred as the means to produce the coated ceramic reinforcing materials of the present invention, any number or alternative processes can be envisioned for obtaining similar results. For example, physical vapor deposition (PVD) processes, sputtering, laser ablation, cathodic arc and even electrophoretic deposition processes among others can be used to produce the novel coated, non-oxide, fibrous ceramic structures of the present invention. Colloidal sol suspensions of, for example, mixed sols of TiO2 and SiO2 can also be used to coat individual fibers or to infiltrate fiber cloths or preforms. In such instances, the impregnated cloth commonly referred to as tow or preform, is heated to a temperature of about 1400xc2x0 C. in an inert gas such as nitrogen or argon for about 2 hours to achieve phase separation and consolidation and subsequently fired at from about 1100xc2x0 C. to about 1600xc2x0 C. for from about one minute up to about 120 minutes prior to incorporation into a ceramic matrix composite structure. All of the structures produced as just described demonstrate significant oxidation resistance at temperatures above 1200xc2x0 C. for extended lifetimes. Incorporation of the coated reinforcing fibers described herein into ceramic matrix composite structures or parts is accomplished by further processing according to well known conventional procedures that involve impregnation of a fiber cloth xe2x80x9clay upxe2x80x9d or preform with an appropriate ceramic matrix and firing of the structure thus produced to yield a ceramic matrix composite part of a desired configuration. There have thus been described a novel class of coated, non-oxide, ceramic reinforcing fibers comprising a core of continuous non-oxide ceramic fiber coated sequentially with, optionally, a pyrolytic carbon layer and a variety of non-hygroscopic, oxidation resistant layer(s). Non-hygroscopic and oxidation resistant compounds of silicon and titanium form the preferred basis of these improved structures. Incorporation of the coated reinforcing fibers of the present invention into ceramic matrix composite structures and parts provides more oxidation resistant and therefore longer lived such parts that are used in or exposed to oxidizing atmospheres especially at high temperatures in excess of 1200xc2x0 C. As the invention has been described, it will be apparent to those skilled in the art that the same may be varied in many ways without departing from the spirit and scope of the invention. Any and all such modifications are intended to be included within the scope of the appended claims.
	abstract	Disclosed embodiments include nuclear fission reactor cores, nuclear fission reactors, methods of operating a nuclear fission reactor, and methods of managing excess reactivity in a nuclear fission reactor.
	claims	1. A method for applying therapeutic radiation to living tissue using a balloon catheter, comprising:inserting into a cavity of the living tissue, through an entry point on a patient, a catheter including an inflatable balloon having a balloon skin doped with a low concentration of contrast medium that will partially block radiation from an external imaging device, and including a guide in the balloon,inflating the balloon in the cavity,performing an external imaging of the balloon to verify the location of the balloon within the cavity such that the imaging passes radiation tangentially through edges of the balloon and thus reveals essentially only an outline of the balloon as a thin peripheral curving line via the contrast medium in the balloon skin, the verifying of balloon placement being performed by detecting the thin peripheral curving outline of the balloon,adjusting the position of the balloon by reference to the external image if necessary,positioning a brachytherapy device at a desired position within the balloon, via the guide of the catheter, andadministering a desired radiation dose from the brachytherapy device in accordance with a dose prescription. 2. The method of claim 1, further including moving the brachytherapy device through multiple locations along a central access of the balloon to obtain an isodose profile as desired per the prescription, then removing the brachytherapy device and the balloon catheter from the cavity. 3. The method of claim 2, further including repeating the step of administering radiation therapy in multiple therapy fractions in accordance with the prescription. 4. The method of claim 1, wherein the brachytherapy device includes a radioactive isotope. 5. The method of claim 1, wherein the brachytherapy device comprises a switchable x-ray tube. 6. The method of claim 5, including inserting the brachytherapy device into the balloon prior to insertion of the balloon into the resection cavity. 7. The method of claim 1, further including draining liquids from the cavity of the living tissue while the inflated balloon is within the cavity, using drain lumens formed in the catheter and extending to exterior of the tissue. 8. The method of claim 7, wherein the balloon wall has an exterior surface with texture to define drain channels to provide a path for flow of liquids toward the exterior of the cavity. 9. The method of claim 8, wherein the balloon catheter has a generally central flexible shaft having drain holes in a distal end of the shaft, distal of the balloon, connected to the drain lumens which pass through the shaft, and further including drain holes in the exterior of the shaft proximal of the balloon for collecting liquids traveling over the surface of the balloon. 10. The method of claim 1, including administering x-ray does from the brachytherapy device at about 5-50 Gy per hour. 11. A method for applying therapeutic radiation to living tissue using a balloon catheter, comprising:inserting into a cavity of the living tissue through an entry point on a patient, a catheter including an inflatable balloon and including a guide in the balloon,inflating the balloon in the cavity,positioning a brachytherapy device at a desired position within the balloon, via the guide of the catheter,administering a desired radiation dose from the brachytherapy device in accordance with a dose prescription, anddraining liquids from the cavity of the living tissue while the inflated balloon is within the cavity, using drain lumens formed in the catheter and extending to exterior of the tissue. 12. The method of claim 11, wherein the balloon wall has an exterior surface with texture to define drain channels to provide a path for flow of liquids toward the exterior of the cavity. 13. The method of claim 12, wherein the balloon catheter has a generally central flexible shaft having drain holes in a distal end of the shaft, distal of the balloon, connected to the drain lumens which pass through the shaft, and further including drain holes in the exterior of the shaft proximal of the balloon for collecting liquids traveling over the surface of the balloon. 14. The method of claim 12, including administering x-ray does from the brachytherapy device at about 5-50 Gy per hour.
052009866	description	DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows an x-ray examination apparatus comprising a C-shaped frame 2 to which are connected an x-ray source 3 and an x-ray image intensifier tube 5. The x-ray source 3 emits a beam of x-rays 7 which after passing through a patient body 8 is detected on the entrance screen of the image intensifier tube 5. In the entrance screen, that comprises for instance CsI, a light image is formed which impinges on a photocathode and liberates electrons therefrom. The electrons are accelerated through a potential difference of for instance 20 kV and impinge on an output screen containing phosphorus to form a light image with increased intensity. The light image on the output screen of the image intensifier tube 5 is detected with a television camera 9 that forms a video signal which is displayed on a television monitor. The C-shaped frame 2 can move in a circumferential direction within a supporting member 11, the supporting member 11 being rotatable around an axis 13. By rotation of the frame 2 in the circumferential direction or by rotation of the supporting member 11 around the axis 13, a central ray 15 connecting the x-ray source 3 and the x-ray image intensifier tube 5 rotates around an isocenter 17. In an x-ray image the isocenter 11 always occupies the same position irrespective of the position of the frame 2. A table height of a patient table 19 is usually chosen such as to place an area of interest within a patient 8 in the isocenter 17. Close to the x-ray source 3 a collimating unit 21 is placed which contains lead shutters 23, FIG. 2, delimiting the x-ray beam 5. FIG. 2 schematically shows the collimating unit 21 which contains lead shutters 23 that can be moved away from and towards the central ray 15. In total there are four lead shutters 23 enclosing a rectangle. In order to get a visual indication of the collimating effect of the shutters 23 on the x-ray beam 7 an x-ray transparent mirror 25 is present in the collimating unit 21. A light source 27, that is in fact contained within the housing 22 of the collimating unit 21, is placed in a position corresponding to a focus 29 of the x-ray source 3. The projection of the lead shutters 23 onto the patient body 8 by the light source 27 corresponds to the field of view of the x-ray image. A filter 31, that comprises a wedge-shaped filter body 33 of for example copper or aluminum, is fixed in the housing 22 and can by means of a motor 34 be translated toward and away from the central ray 15 and be rotated around the central ray. The motor 34 can be activated by a user of the x-ray examination apparatus from a control panel 35, FIG. 2, connected to a side of the patient table 19. The filter 31 can also be placed below the lead shutters 23, or can be used in an x-ray examination apparatus in which no collimating unit 21 is present. FIG. 3 shows a top view of the filter 31 in which the filter body 33 is held between two overlying disk-shaped holding members 37 and 37' (only one of which is shown in FIG. 3) and is movable within a central opening 39 through which the central ray 15 passes, the central ray being perpendicular to the plane of drawing. In the embodiment shown in this figure, two filters 31 are placed on top of one another such that two filter bodies 33 and 33' and four holding member 37, 37', 38 and 38' are present as shown in FIG. 6. The four holding members 37, 37', 38 and 38' can be rotated around the central ray 15 by two motors 34 and 34', FIG. 3. Connected to the motors 34 and 34' are four potentiometers 41 and 41' to determine the angular position of each holding member 37, 37', 38 and 38'. The signal of the potentiometers 41, 41' is for example supplied to a control unit for automatic positioning of the filter bodies 33 and 33' in the x-ray beam. FIG. 4 shows the pair of holding members 37, 37' in a disassembled state. To the holding member 37 the filter body 33 is attached in a pivot-point 43 such as to be rotatable around an axis which runs through the pivot-point and which is perpendicular to the plane of drawing. The filter body 33 is provided with a pawl 45 that extends perpendicular to the plane of drawing and that fits in a curved radial groove 47 in the holding member 37'. The holding member 37' is to be placed on top of the holding member 37 such that the pawl 45 engages the groove 47. When, in the assembled state, the holding members are rotated with respect to one another, the groove 47 forces the filter body 33 to rotate around the pivot-point 43, whereby the filter body 33 covers or uncovers a part of the central opening 39. When both holding members rotate together, the straight edge 48 of the filter body 33 is rotated around the central ray 15 which extends perpendicular to the plane of drawing. FIG. 5 shows a schematic representation of the coupling means, comprising a magnetically energizable brake 42 and two spur gears 53 and 55 that are mutually coupled by means of a layer of friction material 54 such as "Ferodo 3701 F" is supplied by the company Ferodo Limited (GB). When the brake 42 is not energized, the rotation of the spur gear 53, that is driven by the motor 34 and spur gear 50, is transmitted to the spur gear 55 by means of the layer of friction material 54. The layer of friction material 55 is fixedly connected to one of the spur gears 53 or 54. In this way the holding members 37 and 37' are jointly rotated around the central ray 15 with equal angular velocity such that the filter body 33 is rotated around the central ray 15. Energizing the brake 42, results in the spur gear being blocked. Since the coefficient of friction of the layer of friction material 54 is not large enough to prevent rotation of the spur gear 53, only the holding member 37' is rotated around the central ray 15 resulting in translation of the filter body 33. FIG. 6 shows a sectional view of the filter 31. The spur gear 49 is via the spur gear 50 driven by the motor 34. Via the layer of friction material 54, the spur gear 51 is coupled to the spur gear 49. Via a transmission gear, not shown in this figure, the spur gears 49 and 51 cause the holding member 37 and 37' to rotate either jointly or relative to one another depending on whether the electromagnetic brake 42 has been energized or not. Rotation of the spur gear 51 is transmitted to a spindle 40 that is connected to a potentiometer 41 (not shown in this figure) for recording the angular position of the holding member 37. Likewise the spur gears 49, 53 and 55 are each connected to respective potentiometers 41 and 41'.
059784300	claims	1. In a nuclear fuel bundle having a water rod connected to a lower tie plate, apparatus for measuring the length of the water rod comprising a standards rod engageable at one end with the lower tie plate; an indicator location block; said block defining a first reference surface for bearing against a seat on said water rod; a gauge having a movable measuring element mounted on said block with said movable element engageable with an opposite end of said standards rod, said element defining a second reference surface a predetermined distance from said first reference surface at a predetermined gauge indication; whereby, said gauge indicates any deviation of the length of the water rod from a designed length corresponding to the length of the standards rod and said predetermined distance. disposing a standards rod in generally parallel side-by-side relation with the water rod; engaging one end of the standards rod against the lower tie plate; aligning a first reference surface on a location block and a reference surface on said water rod; providing a gauge on said block carrying a movable measuring element defining a second reference surface a predetermined distance from said first reference surface at a predetermined gauge indication; and engaging said element with said standards rod at an opposite end of said standards rod whereby said gauge indicates any deviation of the length of the water rod from a designed length corresponding to the length of the standards rod and said predetermined distance. 2. Apparatus according to claim 1, including a second water rod connected to the lower tie plate, said block having a pair of machined arcuate recesses on and opening outwardly thereof for receiving end portions of the water rods respectively. 3. An apparatus according to claim 2, including a boss on said block for mounting said gauge. 4. Apparatus according to claim 1, including a gauge set block having first and second datum surfaces for calibrating said gauge when said location block is applied to said set block. 5. A method of measuring the length of a water rod in situ in a nuclear fuel bundle, the water rod being connected to a lower tie plate of the bundle comprising the steps of: 6. A method according to claim 5, including applying a gauge set block having first and second datum surfaces to said location block and element of said gauge to calibrate said gauge. 7. A method according to claim 6, wherein said gauge has a digital indicator and including zeroing out the digital indicator when said first datum surface engages a third reference surface on said location block and said element engages said second datum surface. 8. A method according to claim 5, including removing said standards rod, said gauge and said location block from said bundle and, subsequent thereto, applying spacers to said water rod at spaced locations therealong, inserting said standards rod through said spacers, and re-engaging said one end of said standards rod with said lower type plate. 9. A method according to claim 8, including, prior to inserting the standards rod through said spacers, applying a shaped end to the one end of the standards rod to facilitate passage of the standards rod through the spacers and removing the shaped end from the one end of the standards rod prior to re-engaging said one end thereof with said lower tie plate. 10. A method according to claim 8, including inserting fuel rods through said spacers with said standards rod in said fuel bundle and determining any deviation in length of the water rod from the designed length thereof subsequent to insertion of said fuel rods. 11. A method according to claim 10, including after the step of determining, removing the standards rod by withdrawing the standards rod through the spacers in a direction away from said lower tie plate and inserting at least a partial length fuel rod in the fuel bundle in place of the standards rod.
059303140	claims	1. An apparatus for analyzing radiation emitted by an object in response to neutron bombardment, the apparatus comprising a radiation detector array for detecting the energy of gamma rays emitted by the object in response to neutron bombardment and for producing detection signals responsive to the energy of the detected gamma rays, a coded aperture, having a predetermined configuration, disposed between the detector array and the object such that emitted radiation is detected by the detector array after passage through the coded aperture; and a data processor for characterizing the object by substantially determining the elemental composition of the object, disposing a coded aperture, having a predetermined configuration, in selected proximity to the object; interrogating the nuclei of the object with an energy source, the interrogation resulting in emitted radiation, said interrogating step including bombarding said object with fast neutrons, detecting, with a detector, at least a portion of the radiation emitted in response to the nuclear interrogation, the detector producing detection signals responsive to the radiation incident upon the detector after passage through the coded aperture; and processing the detection signals to characterize the object based upon the emitted radiation detected by the detector, and based upon the predetermined configuration of the coded aperture. disposing a coded aperture, having a predetermined configuration, in selected proximity to the object; interrogating the nuclei of the object with an energy source, the interrogation resulting in emitted radiation, said interrogating step including bombarding said object with fast neutrons, detecting, with a detector, at least a portion of the radiation emitted in response to the nuclear interrogation, the detector producing detection signals responsive to the radiation incident upon the detector after passage through the coded aperture; and processing the detection signals to characterize the object based upon the emitted radiation detected by the detector, and based upon the predetermined configuration of the coded aperture, wherein said processing step comprises disposing a coded aperture having a predetermined configuration in selected proximity to the object; generating a beam of fast neutrons; irradiating the object with the beam of fast neutrons, the fast neutrons interacting with atomic nuclei of the elements contained within the object to produce gamma-rays characteristic of the elements contained within the object; measuring the characteristic spectral lines of the gamma-rays using a radiation detector array and a data processor, the gamma-rays having passed through the coded aperture disposed between the object and the radiation detector array; determining density distributions of the elements contained within the object based upon the measured characteristic spectral lines and the predetermined configuration of the coded aperture; comparing the density distributions with known density distributions of the elements of interest. 2. A method of analyzing radiation emitted by an object in response to nuclear interrogation, comprising the steps of: 3. The method of claim 2, wherein the step of interrogating nuclei of the object further comprises bombarding the object with neutrons having energies from about 1 to about 15 MeV. 4. A method of analyzing radiation emitted by an object in response to nuclear interrogation, comprising the steps of: 5. A method of analyzing the elemental composition of an object in response to neutron bombardment, comprising the steps of 6. The method of claim 5, wherein said irradiating step further comprises irradiating the object with a pulsed beam of neutrons. 7. The method of claim 5, wherein said elements of interest are selected from the group consisting of at least oxygen, carbon, nitrogen, hydrogen, and chlorine. 8. The method of claim 5, wherein the method of analyzing the elemental composition includes determining the proportion of any one or more metals in a compound, ore, or alloy. 9. The method of claim 8, wherein the metals include precious metals.
	claims	1. A stencil mask for limiting an irradiation area of charged particles on a surface of a substrate to a predetermined closed loop shape, the stencil mask comprising:a first layer disposed at a side of the stencil mask which faces toward the substrate; anda second layer disposed at a side of the stencil mask to which the charged particles are irradiated, wherein:at least one first penetrating hole having the predetermined closed loop shape is formed in the first layer;a plurality of second penetrating holes is formed in the second layer within a distributing area encompassing the predetermined closed loop shape, the plurality of the second penetrating holes being distributed within the distributing area; anda portion of the second layer separating at least one pair of adjacent second penetrating holes crosses a limited portion of the first penetrating hole when viewed along the traveling path of the charged particles. 2. The stencil mask according to claim 1,wherein the distributing area of the second penetrating holes is larger than the shape of the first penetrating hole when viewed along the traveling path of the charged particles. 3. The stencil mask according to claim 1,wherein the first layer and the second layer are made of semiconductor material, and the first layer and the second layer are in contact with each other. 4. The stencil mask according to claim 1,wherein the portion of the second layer separating at least one pair of adjacent second penetrating holes connects portions of the first layer separated by the first penetrating hole. 5. The stencil mask according to claim 1,wherein each of the second penetrating holes has a convex polygonal shape. 6. The stencil mask according to claim 1,wherein a distance between at least one pair of adjacent second penetrating holes is longer at the side of the second layer to which the charged particles are irradiated than at the side of the second layer facing toward the first layer. 7. A device for irradiating charged particles, comprising:a charged particle generator;a mass analyzer for selecting predetermined charged particles from the charged particles generated by the generator;an accelerator for accelerating the selected charged particles;an irradiating chamber for accepting a substrate, andthe stencil mask according to claim 1 disposed between the accelerator and the substrate being accepted within the irradiating chamber. 8. A method of using a stencil mask, comprising:disposing the stencil mask of claim 1 above a substrate; andirradiating charged particles through the stencil mask to the surface of the substrate. 9. A method of manufacturing a semiconductor device, comprising:disposing the stencil mask of claim 1 above a semiconductor wafer; andirradiating charged particles through the stencil mask to the surface of the semiconductor wafer. 10. A stencil mask for limiting an irradiation area of charged particles on a surface of a substrate to a predetermined closed loop shape with an island portion located within the closed loop, the stencil mask comprising:a first layer disposed at a side of the stencil mask which faces toward the substrate; anda second layer disposed at a side of the stencil mask to which the charged particles are irradiated, wherein:at least one first penetrating hole having the predetermined closed loop shape with the island portion located within the closed loop is formed in the first layer; andat least a portion of the second layer crosses a limited portion of the first penetrating hole and connects the island portion and a portion of the first layer surrounding the first penetrating hole when viewed along the traveling path of the charged particles.
046577238	description	DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to the present preferred embodiment of the invention, an example of which is illustrated in the accompanying drawings. In FIG. 1, there is depicted a tokamak reactor 100 having a TF coil assembly 10 surrounding a toroidal plasma region 20 having a toroidal axis 25. For purposes of illustration, the ohmic heating transformer coil 30 is shown disposed about a central axis 45 and located coaxially interior to the TF coil assembly 10. The tokamak core is located within a vacuum chamber 40 and as will be appreciated by one of skill in the art, has several poloidal field coils 50 in addition to the ohmic heating coil 30 which perform various necessary functions to confine, heat, locate and stabilize the plasma in the plasma region 20. The TF coil means 10 are energized by a power source (not shown) which forms no part of the instant invention, but which when operating causes very large current densitites to flow through the toroidal field coil turns. These high current densities cause Joule heating to occur in the toroidal field coil assembly. In addition, during operation, the plasma in the plasma region 20 radiates both thermal heat and energetic neutrons; the energetic neutrons being an additional source of heat. Because of the above-referenced heating effects, it is necessary to cool the TF coil turns. However, the coils must be cooled in such a manner as to take into account the problem of pressure drop and flow distribution. In addition, the cooling arrangement must not create an excessive void fraction in the TF coil or create excessive material stresses or hot spots associated with getting coolant into and out of each turn of the toroidal field coil. Turning to FIGS. 2, 3 and 4, it can be seen that the TF coil turns are composed of generally flat washer-like disks 11 and 12 joined at a joint 31. The disks have a relatively narrow thickness along the edge 37 as compared to the flat faces 34 and 36. Each coil has a leading end and a trailing end as indicated by numerals 33 and 32, respectively, for coils 12 and 11, respectively. The trailing end 32 of coil 11 is joined at joint 31 with the leading end 33 of coil 12. It is in this manner that the toroidal field coil assembly 10 as shown in FIG. 1 is formed. It will be appreciated by the artisan that in the compact TF coil assembly of the present invention, to provide coolant supply and return headers inside the body of the coil material which were wide enough to allow for coolant flow without unduly high pressure drop and high velocity, would create a void in the TF coil material of such magnitude as to cause electric current bunching in the region of the header (thus creating unduly large I.sup.2 R losses) in addition to very high material stresses. Therefore, in accordance with the present invention, the coolant supply header 19 and coolant return header 17 are positioned along the flat sides 36 and 34 of the TF coil turns 12 and 11, respectively. These headers are positioned just above and below the joint 31. The coolant channels 13 bend outward in the vicinity of the headers 19 and 17 to form inlet openings 21 and outlet openings 16 which, as seen in FIG. 4, are arranged radially to the axis of the tokamak. The general area of the bends is indicated in FIG. 3 by numerals 15 and 22. While the inlet and outlet openings are indicated in FIG. 4 to be rectangular, it will be appreciated by the artisan that they can be circular, elliptical, square or other convenient geometric shapes. The distribution of coolant flowing through the individual coolant channels within each coil turn is affected by the relative pressure drops in the channels and by the pressure drop characteristics of the supply and return headers. Therefore, as shown in FIG. 4, it may be necessary to taper the headers, especially the supply header, so that the flow area decreases, with decreasing radial location from the axis of the tokamak. Tapering the headers also may be desirable in order to maintain clearance between the header and the adjacent TF coil turn. Because the coolant channels 13 bend outward to meet the header structures above and below the joint 31, the present invention avoids the creation of a large void in the region of the joint 31 and the attendant current bunching and high-stress situations. The headers may preferably be cut from round tubes, sections of which are then cut out to conform to the TF coil turns and attached by welding or brazing to the TF coils in such a manner as to enclose the coolant channel inlet and outlet openings. Since the header structure can be welded or brazed to the coil turn after each turn is machined, the fabrication of the coil turn is simplified. In addition, it should be appreciated that while the inlet and outlet header structure depicted is circular, it can alternatively be made of any convenient geometric shape such as elliptical, square or rectangular or can be conformed to accommodate space limitations between turns. Another embodiment of this invention is shown in FIG. 5. TF coil turns 101, 102 and 103 having coolant channels 104 are served by common supply and return headers 105 and 106, respectively, that overlap the joint 107. For this configuration, the coolant flow direction within the coolant channels may preferably alternate from one TF coil turn to the next. This embodiment has the advantages of a uniform temperature within the region of the joint and it halves the required number of headers from, for example, the embodiment of FIG. 3. In the embodiments shown in FIGS. 2, 3, 4, and 5, the coolant flows into the coil turn at one location, flows all the way around the coil turn picking up heat and then flows out at another location. While the embodiments described above have many useful advantages, it will be understood by the artisan that there will exist a substantial variation in the bulk temperature of the coil turn in the direction of coolant flow, i.e., the turn will be at a higher temperature near its coolant outlet than at its coolant inlet. As explained hereinabove, this gives rise to several undesirable characteristics such as high maximum coil temperatures, lower coil strength, deflections and stresses. Turning to FIGS. 6 and 7, side supply headers 49 are positioned on both sides of a joint 50 between adjacent coil turns 56 and 57. As best seen in FIG. 7, each supply header 49 supplies every other coolant channel 55 and each return header 59, services every other coolant channel 52. The result is a cooling arrangement where within each turn of the coil the cooling channels alternate with respect to the direction of coolant flow. Therefore, at any circumferential location around a coil turn, a cut across the coil would yield approximately the same average coil material temperature for the material surrounding two adjacent cooling channels. An additional embodiment requiring only half the number of headers and connections is depicted in FIGS. 8 and 9 wherein a single header is used which overlaps the joint between two coil turns, thus serving both turns simultaneously. Turning now to FIGS. 8 and 9, there is depicted a single supply header, 35 which covers the coolant inlet openings 21 in two adjacent coils 60 and 61. Of course, it should be understood in this embodiment that in alternate coolant channels, coolant flows in the same direction but in adjacent coolant channels, coolant flows in opposite directions. Likewise, return header 36 is positioned to cover joint 31 and outlet openings 16. In this manner, fewer components can be used to construct the cooling arrangement thereby simplifying even further the fabrication of the TF coil. In operation, coolant is flowed from an external source and through a manifold into the supply header. It travels along the supply header which is of a controlled shape so as to achieve proper coolant distribution, pressure drop and flow velocity and into coolant inlet openings 21. The coolant then flows through the bend portion 22 of the coolant channel, through the coolant channel 13. As illustrated in the adjacent coil 61, coolant then flows through the bend portion 15 of the coolant channel and to the outlet of the coolant channel 16 located on the flat face of the TF coil turn. The coolant then flows along the flat face of the TF coil turn, through the return header 36 back to the coolant source through a manifold (not shown) which forms no part of the instant invention. TF coil assemblies built in accordance with this invention are of simplified design and manufacture, and produce good thermal and hydraulic properties with regard to coolant flow. The foregoing description of a preferred embodiment of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto.
047818603	claims	1. A method of disposing of radioactive or hazardous liquid wastes comprising a water soluble or miscible organic liquid, an aqueous solution having a dissolved solids content of about 5,000 parts per million or more, and mixtures thereof comprising adding thereto between about 2.2 and about 5.0 pounds of a clay selected from the group consisting of attapulgite, sepiolite, and mixtures thereof per gallon of said liquid and stirring the mixture under high mechanical shear until it is substantially solidified. 2. The method of claim 1 wherein said composition is subjected to high shear stirring of at lease about 500 rpm. 3. The method of claim 1 wherein said composition is subjected to high shear stirring of at least about 1,000 rpm. 4. A method of disposing of radioactive or hazardous water soluble or miscible organic liquids and having between about 5% and about 95% liquid hydrocarbon by volume, comprising mixing said liquid with a mixture of clay selected from the group attapulgite, sepiolite, and mixtures thereof and an organic ammonium montmorillonite having at least 10 carbon atoms at a ratio of clay:organic ammonium montmorillonite about directly proportional to the ratio of said organic liquid:liquid hydrocarbon, by volume, respectively, and wherein the amount of said clay and organic ammonium montmorillonite mixture is between about 2.5 and about 5.5 pounds per gallon of total bulk liquid, and stirring the mixture under high mechanical shear until it is substantially solidified. 5. The method of claim 4 including adding between about 1 and about 10% by volume of a polar organic compound based on the hydrocarbon. 6. The method of claim 4 including adding between about 1 and about 10% of an alcohol having between 1 and 3 carbon atoms based on the hydrocarbon. 7. A method of disposing of an aqueous radioactive or hazardous liquid having a dissolved solids content of between about 5,000 and about 30,000 parts per million comprising adding thereto a mixture of between about 55% and about 95% of a clay selected from the group consisting of attapulgite, sepiolite, and mixtures thereof and between about 5% and about 45%, by weight, sodium montmorillonite having sodium as the major exchangeable cation, said mixture added in an amount of between about 1.5 and about 4.0 pounds per gallon of said liquid, and stirring the mixture under high mechanical shear until it is substantially solidified. 8. A substantially solidified hazardous or radioactive composition consisting essentially of water soluble or miscible organic liquid, an aqueous solution having a dissolved solids content of at least about 20,000 parts per million, and mixtures thereof, and between about 2.2 and about 5.0 pounds of a clay selected from the group consisting of attaqulgite, sepiolite, and mixtures thereof per gallon of liquid. 9. The composition of claim 8 wherein said water soluble or miscible organic liquid is selected from the group consisting of polyhydric alcohols, glycyerols, and plyalkylene glycols. 10. A substantially solidified hazardous or radioactive composition consisting essentially of an aqueous solution having between about 5,000 and about 30,000 parts per million dissolved solids and a mixture of between about 55% and about 95% by weight of a clay selected from the group consisting of attapulgite, sepiolite, and mixtures thereof, and between about 5% and about 45%, by weight sodium montmorillonite having sodium as the major cation said mixture of said clay and sodium montmorillonite being present in an amount of between about 1.5 and about 4.0 pounds per gallon of said liquid. 11. The composition of claim 10 including between about 5 and about 95% by volume based on said aqueous solution of a water soluble or miscible organic waste liquid selected from the group consisting of aldehydes, ketones, acids, ethers, esters, alcohols, polyols and polyglycols. 12. A substantially solidified hazardous or radioactive composition consisting essentially of a water soluble or miscibel organic liquid and a liquid hydrocarbon and a mixture of a clay selected from the group consisting of attapulgite, sepiolite, and mixtres thereof and an organic ammonium montmorillonite having at least 10 carbon atoms wherein said amount of said clay and said organic ammonium montmorillonite is between about 2.5 and about 5.5 pounds per gallon of said liquid. 13. The composition of claim 12 wherein the liquids comprise between about 5% and about 95% organic liquid and between about 5% and about 95% liquid hydrocarbon, by volume, and wherein the ratio of said clay:organic ammonium montrmorillonite is about directly proportional to the ratio of said organic liquid:liquid hydrocarbon, respectively. 14. The method of claim 1 including substituting between about 5 and about 45% of said clay with sodium montmorillonite.
	claims	1. A power module comprising:a reactor core having horizontal and vertical surfaces; anda reflector partially surrounding the vertical surfaces of the reactor core to improve a neutron efficiency of the power module, wherein the reflector comprises one or more inlets located in the vertical surfaces adjacent the reactor core, and wherein the one or more inlets are configured to receive coolant that has passed through at least a portion of the reactor core prior to entering the one or more inlets, and whereinthe reflector comprises a plurality of horizontal plates, and wherein the horizontal plates adjacent a bottom portion of the reflector are thinner than the horizontal plates adjacent a top portion of the reflector. 2. The power module according to claim 1, wherein the one or more inlets comprises a plurality of inlets, and the reflector further comprises a plurality of outlets located at an upper end of the reflector, and wherein each inlet of the plurality of inlets is connected to a corresponding outlet of the plurality of outlets, the inlet and the corresponding outlet being coupled by a channel that passes through the reflector. 3. The power module according to claim 2, wherein a portion of the channel coupled to the inlet is oriented in an approximately horizontal direction. 4. The power module according to claim 3, wherein a portion of the channel connected to the corresponding outlet is oriented in an approximately vertical direction. 5. The power module according to claim 1, further comprising a reactor housing that surrounds the reactor core about its sides to direct the coolant through the reactor core, wherein the reflector is located between the reactor housing and the reactor core. 6. The power module according to claim 1, wherein the one or more inlets comprise a plurality of inlets located at different elevations. 7. The power module according to claim 6, wherein a first inlet located at a lower elevation is configured to receive coolant that passes through a lower portion of the reactor core, and wherein a second inlet located at a higher elevation is configured to receive coolant that passes through an upper portion of the reactor core. 8. A nuclear reactor module comprising:a reactor core;a reactor housing that surrounds the reactor core about the sides of the reactor core, wherein the reactor housing is configured to direct coolant through the reactor core; anda neutron reflector located between the reactor core and the reactor housing, wherein the neutron reflector includes a plurality of inlet ports facing the reactor core, and wherein the neutron reflector further includes a plurality of outlet ports fluidly connected to the inlet ports to direct a portion of the coolant through the neutron reflector, whereinthe neutron reflector comprises a plurality of plates layered together, wherein a channel is formed between adjacent plates of the neutron reflector, and wherein the channel fluidly connects an inlet port to an outlet port, andwherein at least some of the plurality of plates have different thicknesses, and wherein distance between inlet ports increases adjacent a top portion of the reflector and decreases adjacent a bottom portion of the reflector. 9. The nuclear reactor module according to claim 8, wherein the channel comprises an approximately horizontal channel that passes between the adjacent plates. 10. The nuclear reactor module according to claim 9, wherein the channel comprises an upper portion that is recessed into a lower surface of a first plate, wherein the channel comprises a lower portion that is bounded by an upper surface of a second plate, and wherein the lower surface of the first plate is located adjacent to the upper surface of the second plate. 11. The nuclear reactor module according to claim 9, wherein the approximately horizontal channel is connected to an approximately vertical channel that passes through two or more of the plurality of plates. 12. The nuclear reactor module according to claim 11, wherein the horizontal channel is connected to one of the inlet ports, and wherein the vertical channel is connected to one of the outlet ports. 13. The nuclear reactor module according to claim 8, wherein the number of channels comprises one or more sloped channels. 14. The nuclear reactor module according to claim 8, wherein at least some of the plurality of plates have different thicknesses, and wherein a distance between inlet ports varies according to the different thicknesses of the plurality of plates. 15. A power module comprising:a reactor core comprising a lateral surface, a first end surface, a second end surface, and a flow path defined between and through the first and second end surfaces; anda reflector at least partially surrounding the lateral surface of the reactor core and comprising at least two fluid circuits defined through the reflector, at least one of the fluid circuits comprising a portion that is transverse to the flow path, the at least two fluid circuits fluidly coupled between a portion of the flow path between the first and second end surfaces of the reactor core and a portion of the flow path that exits the reactor core at the second end surface of the reactor core. 16. The power module of claim 15, wherein the portion of the at least one fluid circuit comprises a first portion substantially perpendicular to the flow path, and the at least one fluid circuit further comprises a second portion substantially parallel to the flow path and fluidly coupled to the first portion of the fluid circuit. 17. The power module of claim 16, wherein the first portion is fluidly coupled to the portion of the flow path between the first and second end surfaces of the reactor core, and the second portion is fluid coupled to the portion of the flow path exiting the reactor core at the second end surface of the reactor core. 18. The power module of claim 16, wherein the reflector comprises a plurality of plates layered together, and substantially all of the first portion of the fluid circuit is defined through only one of the plurality of plates, and substantially all of the second portion of the fluid circuit is defined transversely through two or more of the plurality of plates. 19. The power module of claim 18, wherein one or more plates of the plurality of plates adjacent a bottom portion of the reflector is thinner than one or more plates of the plurality of plates adjacent a top portion of the reflector. 20. The power module according to claim 15, wherein the reflector further comprises a substantially vertical channel extending between a lower end surface of the reflector that is substantially coplanar with the first end surface of the reactor core and an upper end surface of the reflector that is substantially coplanar with the second end surface of the reactor core. 21. The power module according to claim 20, wherein the two or more fluid circuits defined through the reflector are fluidly decoupled from the substantially vertical channel. 22. The power module according to claim 15, further comprising a reactor housing that surrounds the reflector.
	description	This application claims the benefit of U.S. Provisional Application No. 61/764,404 filed Feb. 13, 2013 and titled “Shipping Container for Unirradiated Nuclear Fuel Assemblies”. U.S. Provisional Application No. 61/764,404 filed Feb. 13, 2013 is hereby incorporated by reference in its entirety into the specification of this application The following relates to the nuclear reactor fuel assembly packaging and transportation arts, to shipping containers for unirradiated nuclear fuel assemblies, to apparatus for manipulating such shipping containers, to shipping and handling methods utilizing same, and to related arts. Unirradiated nuclear fuel assemblies for light water nuclear reactors typically comprise 235U enriched fuel pellets, and in a typical configuration comprise an array of parallel fuel rods each comprising a hollow cladding inside of which are disposed 235U enriched fuel pellets. The 235U enrichment of the fuel pellets is typically less than 5% for commercial nuclear power reactor fuel. Transportation of unirradiated nuclear fuel assemblies is accomplished using shipping containers that meet appropriate nuclear regulatory rules, e.g. Nuclear Regulatory Commission (NRC) rules in the United States. Under NRC rules, the shipping containers are designed to preclude the release of radioactive material to the environment and to prevent nuclear criticality from occurring in the event of postulated accidents. Furthermore, the shipping containers are designed to protect the unirradiated fuel from damage during shipment. Existing nuclear fuel shipping containers are typically “clamshell” designs that are rectangular or cylindrical in shape and consist of a lower shell, one or more internal “strongbacks” that support the fuel assemblies, and a removable top shell that encloses the fuel assemblies. A flanged joint between the top and bottom shells allow the container to be opened and closed by bolted or pinned connections along the periphery of the container. A fuel assembly is generally loaded into the shipping container by removing the top shell from the container and lifting the empty lower shell to a vertical position. The fuel assembly is positioned vertically when not supported by a strongback. The vertical fuel assembly is lifted with a crane and then moved laterally (i.e. sideways while remaining suspended upright by the crane) into the upright lower shell of the clamshell container until it is positioned against the strongback of the container. In some designs, several clamps along the length of the fuel assembly may be incorporated to secure the fuel assembly to the strongback. Some designs utilize hinged doors that cover the fuel and are clamped in place to secure the fuel assembly. After the fuel assembly is secured, the shipping container is placed in a horizontal position and the top shell is installed. The shipping container is shipped in the horizontal position. At the nuclear reactor site, the process is reversed, i.e. the top shell is removed, the lower shell with the fuel assembly still loaded on the strongback is up-ended from the horizontal position to the vertical position, and the fuel assembly is unclamped from the strongback and lifted out using a crane and loaded into the nuclear reactor. See, e.g. Sappey, U.S. Pat. No. 5,263,064; Sappey, U.S. Pat. No. 5,263,063. The clamps and doors used in clamshell type shipping containers have certain disadvantages. For example, the hinged connections and clamping mechanisms can generate metal shavings that can become trapped inside the fuel assemblies and lead to fretting failure of the fuel rods. The mechanical parts such as bolts, nuts, and washers, can become detached and may lead to fuel rod failure if the loose parts become trapped inside the fuel assembly. The securing mechanisms entail certain adjustments to avoid applying excessive forces on the fuel assemblies, and have the potential to become loose during transport. These securing mechanisms also adds time to the processes of loading and unloading the fuel assemblies from the containers. Moreover, the clamshell container can hold only one or two fuel assemblies, such that the complete set of loading and unloading operations may need repeated for each fuel assembly that is transported from the factory to the nuclear reactor site. The operation of moving the shipping container (or lower shell) with loaded fuel between the horizontal and vertical positions is typically performed using a dedicated piece of equipment, which is referred to in the art as an “up-ender” (even when used to move the loaded shipping container from the vertical position to the horizontal position). Existing up-enders are typically complex dedicated pieces of equipment that have numerous components and that occupy substantial storage space when not in use. See, e.g. Ales et al., U.S. Pub. No. 2007/0241001 A1. In one disclosed aspect, a shipping container comprises: a tubular or cylindrical shell having a closed end and an open end; a top end-cap removably secured to the open end of the tubular or cylindrical shell; and at least one fuel assembly compartment defined inside the tubular or cylindrical shell, each fuel assembly compartment including elastomeric sidewalls and sized and shaped to receive an unirradiated nuclear fuel assembly through the open end of the tubular or cylindrical shell. In some embodiments each fuel assembly compartment has a square cross-section sized to receive an unirradiated nuclear fuel assembly having a square cross-section, and the tubular or cylindrical shell includes support features protruding outward from the tubular or cylindrical shell, the support features being configured to support the shipping container horizontally on a level floor with the sides of the square cross-section of each fuel assembly compartment oriented at 45 degree angles to the level floor. In some embodiments each fuel assembly compartment has a square cross-section sized to receive an unirradiated nuclear fuel assembly having a square cross-section, and the shipping container further includes a divider component having a cross-shaped cross-section with ends of the cross secured to inner walls of the tubular or cylindrical shell, the divider component and the inner walls of the tubular or cylindrical shell defining four said fuel assembly compartments. In another disclosed aspect, an apparatus comprises a shipping container as set forth in the immediately preceding paragraph, and an unirradiated nuclear fuel assembly comprising 235U enriched fuel disposed in each fuel assembly compartment of the shipping container and compressing the elastomeric sidewalls of the fuel assembly compartment. In some such apparatus, each unirradiated nuclear fuel assembly comprises an array of parallel fuel rods each comprising a hollow cladding inside of which are disposed 235U enriched fuel pellets. In another disclosed aspect, a method comprises: arranging a shipping container comprising a tubular or cylindrical shell having a closed end and an open end into a vertical orientation in which the tube or cylinder axis of the cylindrical shell is oriented vertically with the closed end oriented down and the open end oriented up; loading an unirradiated nuclear fuel assembly comprising 235U enriched fuel through the open end of the tubular or cylindrical shell into a fuel assembly compartment defined inside the tubular or cylindrical shell; and after the loading, closing off the open end of the tubular or cylindrical shell by securing a top end-cap to the open end of the tubular or cylindrical shell. In some such methods, the shipping container includes N fuel assembly compartments defined inside the tubular or cylindrical shell where N is greater than or equal to two, and the loading is repeated N times to load N unirradiated nuclear fuel assemblies into the N respective fuel assembly compartments. A more complete understanding of the processes and apparatuses disclosed herein can be obtained by reference to the accompanying drawings. These figures are merely schematic representations and are not intended to indicate relative size and dimensions of the assemblies or components thereof. Although specific terms are used in the following description for the sake of clarity, these terms are intended to refer only to the particular structure of the embodiments selected for illustration in the drawings, and are not intended to define or limit the scope of the disclosure. In some illustrative embodiments, a shipping container comprises a plurality of fuel compartments, each fuel compartment comprising a first side and a second side; a chamber wall enclosing a portion of the fuel compartment; a shock absorbing material peripherally surrounding the chamber wall, and an outer shell peripherally surrounding shock absorbing material. In some illustrative embodiments, a method for loading a fuel assembly in a shipping container comprises: positioning a shipping container vertically in a loading stand; disassembling a container top removably assembled to a outer shell at a first end of the shipping container; loading a fuel assembly vertically at a first end of the shipping container into the a fuel assembly chamber; and reassembling the container top to the outer shell at a first end of the shipping container. With reference to FIGS. 1-5, an illustrative shipping container 10 comprises an outer shell 12 surrounding and containing one or more (four, in the illustrative example) fuel assembly compartments or chambers 14 as shown in the perspective and top-end views of respective FIGS. 3 and 4. The shell 12 is cylindrical or tubular in shape. The terms “tubular” and “cylindrical” are used interchangeably herein to indicate that the shell 12 is an elongate hollow element. The tubular or cylindrical shell 12 is not limited to any particular cross-sectional shape, e.g. the tubular or cylindrical shell 12 can have various cross-sectional shapes including but not limited to a circular cross-section, a hexagonal cross-section, a square cross-section, or so forth. The tubular or cylindrical shell 12 can also be constructed to have different cross-sectional shapes for the outside of the shell 12 versus the inner volume of the shell 12. Each fuel assembly compartment or chamber 14 is sized and shaped to receive a fuel assembly. The top-end views of FIGS. 3 and 4 show one chamber containing a loaded fuel assembly FA, while the remaining three chambers are empty. While the illustrative shipping container 10 includes four fuel assembly chambers 14, more generally the number of fuel assembly chambers can be one, two, three, four, five, six, or more. The illustrative fuel assembly chambers 14 have square cross-sections coinciding with or slightly larger than the square cross-section of the illustrative fuel assembly FA; more generally, each chamber has a cross-section comporting with the cross-section of the fuel assembly, e.g. if the fuel assemblies have hexagonal cross-sections then the chambers preferably have hexagonal cross-sections. In one contemplated embodiment, the fuel assembly compartments or chambers 14 are sized to receive fuel assemblies with square cross-sections in the range of about 8 inches×8 inches to about 9 inches×9 inches. As seen in FIGS. 1 and 5, the shipping container 10 further includes a lower or bottom end-cap 16 and an upper or top end-cap 18. The shipping container is designed for top-loading, and FIG. 1 shows the shipping container 10 oriented vertically (that is, with the tube or cylinder axis of the tubular or cylindrical shell 12 oriented parallel with the direction of gravity and transverse to a level floor) for loading with the top end-cap 18 located at the highest point and the bottom end-cap 16 located at the lowest point. FIG. 2 shows the shipping container 10 in its vertical position for loading with the upper end-cap 18 removed to allow access to the fuel assembly chambers 14 from above, as seen in the top end views of FIGS. 3 and 4 in which the top end-cap has been removed. After four fuel assemblies are loaded into the four chambers 14 (note however it is contemplated to leave one or more of the chambers 14 empty, that is, it is not necessary to load all four chambers for safe transport), the top end-cap 18 is replaced, and the shipping container 10 is moved to a horizontal position (that is, with the tube or cylinder axis of the tubular or cylindrical shell 12 oriented transverse to the direction of gravity and parallel with a level floor) as shown in FIG. 5 for transport. In the horizontal position of FIG. 5, the two end-caps 16, 18 are at (approximately) the same level or height. The illustrative shell 12 includes forklift engagement features 20 via which a forklift or other machinery can engage, lift, and manipulate the shipping container 10 while in its horizontal position. The illustrative shell 12 also includes lower and upper support features or flanges 22, 24 on which the shipping container 10 rests when on a flat floor or other flat surface. Optionally, the support features or flanges 22, 24 may also constitute securing flanges via which the respective end-caps 16, 18 are secured. (The forklift engagement features 20 may provide additional or alternative support, or alternatively the forklift engagement features 20 may protrude outward less than the support features or flanges 22, 24 such that the shipping container 10 in its horizontal position is supported only by the flanges 22, 24). In FIGS. 1, 2, and 5, the two end-caps 16, 18 are visually the same. In some embodiments, the two end-caps 16, 18 are actually structurally identical, and either end can be chosen as the “top” for loading. In other embodiments, the bottom end-cap 16 is structurally distinct from the top end-cap 18, for example by including support foam and/or other support element(s) to support the weight of the loaded fuel assembly FA when the shipping container 10 is in the upright or vertical position shown in FIGS. 1 and 2. Regardless of whether the bottom end is structurally distinct or structurally the same as the top end, it is generally appropriate to have some designation of the upper end, e.g. a “THIS END UP” marking to denote the upper end of the shell 12, since the fuel assemblies typically have defined distinct upper and lower ends. Since the lower end-cap 16 is not removed for the top-loading of the fuel assemblies, it is contemplated for the lower end-cap 16 to be permanently secured to the lower end of the shell 12, for example by welding, or for the lower end-cap 16 to be an integral part of the outer-shell 12, e.g. the shell 12 and the lower end-cap 16 may be a continuous single-piece element. On the other hand, the upper end-cap 18 is removed for the top-loading. In some embodiments the upper end-cap 18 is secured to the upper end of the shell 12 by bolts or other removable fasteners engaging the upper end of the shell 12 and/or the upper support feature or flange 24. The upper end-cap 18 may also be welded to the upper end of the shell 12, but in this case the welds should be breakable by a suitable mechanism, e.g., by using a pry bar. Conversely, while the lower end-cap 16 is not removed for loading or unloading fuel, it is contemplated for the lower end-cap 16 to be secured by bolts or other removable fasteners. The ability to remove the lower end-cap 16 can be advantageous for performing inspection and cleaning of the fuel assembly chambers 14. Because the shipping container 10 is top-loaded, there is no need for the shell 12 to be constructed as a clam-shell. In some embodiments, the shell 12 is a single-piece tubular or cylindrical element (where the terms “tubular” and “cylindrical” do not require a circular cross-section), e.g. formed by extrusion, casting, forging, or so forth. A continuous single-piece tubular or cylindrical outer-shell has advantages in terms of providing a high level of mechanical strength. However, it is also contemplated to construct the shell 12 as two or more pieces that are welded together or otherwise joined, optionally with a strap banding the pieces together. In such embodiments, the welding, strapping or other joinder can be a permanent joinder (as opposed to being separable to open the shipping container as is the case in conventional clamshell shipping containers), although a separable joiner could also be used, e.g. to facilitate inspection and cleaning of the fuel assembly chambers 14. With particular reference to FIGS. 3 and 4, each fuel assembly chamber 14 is square in cross section (or otherwise conforms with the cross-sectional shape of the fuel assembly, e.g. may be hexagonal in order to support fuel assemblies with hexagonal cross-sections) and is commensurate with or slightly larger than the space envelope of the fuel assembly FA, so that the fuel assembly FA can be inserted into the fuel assembly chamber 14 without excessive drag. In the illustrative embodiment, the horizontal support elements 20, 22, 24 are oriented respective to the illustrative square fuel assembly chambers 14 such that each fuel assembly FA is oriented with its sides at 45° angles to the supporting floor (or, equivalently, at 45° angles to the direction of gravity). This provides distributed support for each fuel assembly FA along two of the four sides of the illustrative square fuel assembly FA. In addition to providing extended support, this diagonal orientation suppresses lateral movement of the fuel assembly FA in the fuel assembly chamber 14. With particular reference to FIGS. 3 and 4, the fuel assembly compartments or chambers 14 are defined inside the shell 12 by a divider component 30 that extends most or all of the length of the interior space of the shell 12 and has a cross-sectional shape that, together with the shell 12, defines the cross-sections of the fuel assembly chambers 14. For the illustrative shipping container 10 having four fuel assembly chambers 14, the divider component 30 suitably has a cross-shaped cross-section with the ends of the cross secured to the inner walls of the shell 12, as seen in FIGS. 3 and 4. The divider component 30, along with the inner walls of the shell 12, defines the structural walls of the fuel assembly chambers 14. It will be appreciated that for embodiments in which the shipping container is designed or configured to contain only a single fuel assembly, the divider component may be omitted entirely such that there is a single fuel assembly compartment or chamber defined inside the shell 12. The divider component 30 may be manufactured as a single-piece, e.g. a single-piece cast element, or may be manufactured as two or more planar pieces that are welded together and to the inner walls of the shell 12. In the illustrative embodiment, the inner wall of the shell 12 includes axially oriented grooves 32 (that is, grooves that run parallel with the tube or cylinder axis of the tubular or cylindrical shell 12). These axially oriented grooves 32 receive the cross ends of the cross-shaped (in the sense of having a cross-shaped cross-section) divider component 30. The optional grooves 32 provide convenient alignment for the divider component 30. In a suitable assembly approach, the divider component 30 is top-loaded into the shell 12 by fitting the cross ends into the grooves 32 and sliding the divider component 30 into the shell 12. If the grooves 32 are provided then it is contemplated to rely entirely on the fitting between the grooves 32 and the cross ends of the divider component 30 (along with the end-caps 16, 18) to secure the divider component 30 in place inside the shell 12. Alternatively, tack welding, bolts or other fasteners, or other additional securing mechanism(s) may be employed. An advantage of the shipping container 10 is that the fuel assembly chambers 14 are designed to provide support for the loaded fuel assemblies FA without the use of straps or a dedicated strongback. Toward this end, the shell 12 and the divider component 30 defining the structural walls of each fuel assembly chamber 14 suitably comprise stainless steel, an aluminum alloy, or another suitably strong material, and the inside of the shell 12 is suitably lined with compressible elastomeric material to protect the fuel assembly FA from damage during installation and shipping. In the illustrative embodiment of FIGS. 3 and 4, the elastomeric material includes a relatively harder and relatively thicker structural shock absorbing foam 34 lined on the inside with a relatively softer and relatively thinner shock absorbing foam 36. It is also contemplated to employ only a single layer of elastomeric material, or to employ three or more layers with different thicknesses, elastomeric and/or structural characteristics. The foam or other elastomeric material 34, 36 is preferably sized such that it is compressed slightly as the fuel assembly is loaded into the chamber, thus preventing excessive movement of the fuel during transport. The thickness(es) and elastomeric characteristics of the elastomeric material 34, 36 are readily optimized to provide sufficient cushioning and to suppress movement of the fuel during transport while also not producing excessive drag when loading and unloading fuel assemblies. In some embodiments the elastomeric material 34, 36 is a consumable element that is replaced each time the shipping container 10 is used for a fuel shipment. Optionally, a protective sheet of thin plastic material (not shown) covers each side of the fuel assembly chamber 14 to prevent foam particulates from contacting the loaded fuel assembly. In one embodiment, the protective sheet of plastic is lined with a thin foam backing and the thin foam backing compresses slightly when the shipping container 10 is loaded with fuel. The fuel assembly chambers 14 are also designed to prevent nuclear criticality from occurring in the event of postulated accidents. Toward this end, the divider component 30 and the shell 12 comprise a neutron moderator material (e.g. nylon-6) and/or a neutron absorbing material (e.g. borated aluminum). The neutron moderator and/or neutron absorber materials may be bulk materials making up the structural elements 12, 30, or may be formed as continuous layers or coatings on these elements 12, 30 of thickness effective to prevent or suppress transfer of neutrons generated by radioactive decay events in one fuel assembly from reaching another fuel assembly. Various combinations of bulk and layered neutron moderators or absorbers are also contemplated. A given bulk material or layer may also provide both neutron moderator and neutron absorbing functionality. In one suitable configuration, a boron-impregnated neutron absorber material is interposed between neutron moderator layers of successive fuel assembly chambers 14 for criticality control. By use of suitably designed neutron moderator and/or absorber layers or elements, different fuel assembly types and varying fuel enrichments can be accommodated, including 235U enrichment levels above 5% (the current upper limit for similar containers). Although not illustrated, it will be appreciated that the end-caps 16, 18 can also be constructed with elastomeric material and/or neutron moderating and/or absorbing material. As previously mentioned, the lower end-cap 16 may include additional cushioning elastomeric material so as to support the fuel assembly 14 when the shipping container 10 is loaded and in the upright (vertical) position. With particular reference to FIG. 5, after end-loading of the shipping container 10 the top end-cap 18 is replaced and secured onto the upper end of the shell 12 and the shipping container 10 is placed into its horizontal position (shown in FIG. 5) for shipping. The shell 12 and end-caps 16, 18 of the shipping container 10 are constructed to comply with mechanical stress tests in conformance with applicable nuclear regulatory rules. For example, in the United States the NRC requires that the shipping container 10 withstand specified “drop tests” in various orientations. In the illustrative shipping container 10, the illustrative end-caps 16, 18 have impact energy-absorbing conical shapes that are designed to crumple to absorb an impact in order to protect the shipping container contents. Other shapes for the end-caps can be employed (cf. FIGS. 7 and 8 which employ flat end-caps, of which only the flat top end-cap 18′ is visible in FIGS. 7 and 8). With reference to FIG. 6, a side view is shown of the shipping container 10 secured in a loading stand 40 with an illustrative fuel assembly FA being loaded into (or unloaded from) one of the fuel assembly chambers. The upper end-cap 18 is shown off to the side on the loading stand 40. The weight of the shipping container 10 in its vertical or upright position is suitably supported in the loading stand 40 by a collar or other fastening to the loading stand 40, or by the lower end-cap 16, or by a combination of such mechanisms. The loading stand 40 provides lateral support to ensure the shipping container 10 does not move laterally during loading or unloading. Although not shown in FIG. 6, it is to be appreciated that the fuel assembly FA is loaded or unloaded using a crane or other suitable lifting apparatus engaging and lifting the fuel assembly FA. For example, Walton et al., U.S. Pub. No. 2013/0044850 A1 published Feb. 21, 2013 and incorporated herein by reference in its entirety discloses a lifting tool for a crane designed to engage mating features 42 at the top end of the fuel assembly FA to enable the crane to lift the fuel assembly for vertical loading into (and unloading from) a nuclear reactor, and such a tool is readily employed for top-loading or unloading the fuel assembly FA into or out of the shipping container 10. This is merely an illustrative example, and other fuel handling apparatus designed for top-loading and unloading fuel into and out of a nuclear reactor can readily be applied in loading or unloading the shipping container 10. As seen in FIG. 6, the fuel assembly FA comprises an array of parallel fuel rods, and during the loading these fuel rods are aligned parallel with the tube or cylinder axis of the tubular or cylindrical shell 12 so that the fuel assembly FA can be top loaded into the fuel assembly chamber. In a typical configuration, each fuel rod comprises a hollow cladding inside of which are disposed 235U enriched fuel pellets (details not shown). The 235U enrichment of the fuel pellets is typically less than 5% for commercial nuclear power reactor fuel. In some contemplated embodiments, two or more different divider components may be provided which fit into the shell 12, and the shipping container 10 may be reconfigured to ship different fuel assemblies of numbers, sizes, or cross-sectional shapes by inserting the appropriate divider component into the shell 12 (or, for shipping a single large fuel assembly, not inserting any of the available divider components). Typically, the axial length of the tubular or cylindrical shell 12 (that is, its length along the tube or cylinder axis) is chosen to provide the fuel assembly chambers 14 sufficient length to accommodate the fuel assemblies FA, and optionally tensioners can be employed in one or both end-caps 16, 18 to suppress axial load shifting. It is also contemplated to provide removable spacers and/or tensioners at the top and/or bottom of a fuel assembly chamber 14 in order to accommodate fuel assemblies of different lengths (i.e. different vertical heights). Advantageously, no clamping devices are required to restrain the fuel assembly laterally in the disclosed shipping container designs. The lack of fuel assembly clamping devices or doors to restrain the fuel assemblies provides a number of possible advantages, including, but not limited to, eliminating the possibility of loose parts such as bolts, screws, nuts, washers, and metal shavings from the movement of the clamps during removal and installation, that can become trapped in the fuel assembly and cause fuel rod failure due to fretting. Furthermore, the lack of moving parts such as clamps and doors reduces the time required to load and unload the fuel assemblies into and from the shipping container. The disclosed shipping containers are also top-loaded, which allows the shipping container to be positioned vertically without the use of a mechanical up-ender and the container top may be removed in the vertical position, thus saving time and floor space. The disclosed shipping containers are also easily sealed. If the shell 12 is a single-piece tubular or cylindrical element, then the only sealing surfaces are at lower and upper end-caps 16, 18; and of these, only the upper end-cap 18 is removed for loading and unloading fuel assemblies. This limited length of sealing surface reduces the likelihood of inadequate sealing. The disclosed shipping containers are top-loaded and top-unloaded, which has advantages including allowing the loading and unloading to be performed using a crane to manipulate the fuel assemblies using crane lift and transfer operations similar to those used in loading and unloading fuel from the nuclear reactor core. However, the fuel transport process includes the operations at the fuel source location of moving the loaded shipping container from the vertical position to the horizontal position for transport; and then at the nuclear reactor site “up-ending” the loaded shipping container from the horizontal position to the vertical position for unloading. Conventionally, these operations employ dedicated equipment, referred to in the art as an “up-ender”. Existing up-enders are typically complex dedicated pieces of equipment that have numerous components and that occupy substantial storage space when not in use. An up-ender must be provided at both the fuel source location and at the nuclear reactor site (or, alternatively, a single up-ender can be transported between these two sites, for example integrated into the bed of the transport truck). With reference to FIGS. 7 and 8, an improved up-ender 50 is disclosed, which is constructed as a tool for a crane or hoist. The tool includes a lifting anchor element, e.g. an illustrative lifting beam 52, and an auxiliary winch 54. Rigging lines 56 have upper ends secured to the lifting anchor element 52 and extend generally downward from the lifting anchor element 52. Winch cabling 58 extends generally downward from the auxiliary winch 54. A hook 60 or other connection to a crane or hoist (not shown) connects with the lifting anchor element 52 so that the crane or hoist can raise or lower the lifting anchor element 52. The lifting anchor element 52 can take other shapes and forms besides the illustrative beam configuration. The winch 54 may be separate from the lifting anchor element 52, as illustrated, or may be integrated with (e.g. housed inside) the lifting anchor element. If the winch 54 is separate from the lifting anchor element 52 (as shown), then the winch 54 is connected with the lifting anchor element 52 such that operating the crane or hoist to raise (lower) the lifting anchor element 52 also raises (lowers) the winch 54 together with the lifting anchor element 52. The winch 54 has a motorized spool assembly or other mechanism (not shown) by which the length of the winch cabling 58 extending downward from the winch 54 can be lengthened or shortened. In such embodiments, control of the winch 54 can be via a wireless communication link, or via a signal cable extending from the winch 54. Alternatively, a motorized spool assembly or other mechanism may be integrated with the crane or hoist and the winch cabling 58 passed through the auxiliary winch 54 to the mechanism in the crane or hoist in order to lengthen or shorten the winch cabling. In contrast to the winch cabling 58, the illustrative rigging lines 56 are of fixed length (although some motorized mechanism for length adjustment of the rigging lines is also contemplated). The up-ender 50 is shown engaging a shipping container 10′ oriented in the horizontal position in FIG. 7, and engaging the same shipping container 10′ oriented in the vertical position in FIG. 8. The illustrative shipping container 10′ is similar to the shipping container 10 described with reference to FIGS. 1-6, but the conical end-caps 16, 18 of the shipping container 10 are replaced by flat end-caps, of which only the flat top end-cap 18′ is visible in FIGS. 7 and 8. The shipping container 10′ of FIGS. 7 and 8 also differs from the shipping container 10 of FIGS. 1-6 in that the shipping container 10′ includes: at least one lifting connection 70 connected at some point along the shipping container 10′ (in the illustrative embodiment, two lateral lifting features 70 at opposite sides of the shipping container 10′ near the center of the shipping container 10′) and to which the lower ends of the rigging lines 56 connect; and at least one top connection 72 at the top of the shipping container 10′ to which the winch cabling 58 connects. In the illustrative example, the winch cabling 58 connects with two top connections 72 via a fixture 74; however, a direct connection is also contemplated. The top connection can be made either to the top of the shell 12 (as shown) or, if the top end-cap is sufficiently well-secured to the shell 12, can be made to the top end-cap. Operation of the illustrative up-ender 50 is as follows. The up-ending process (that is, transition from the horizontal position shown in FIG. 7 to the vertical position shown in FIG. 8) starts with connecting the lower ends of the rigging lines 56 to the lateral lifting features 70 of the shipping container 10′, and connecting the lower end of the winch cabling 58 to the top connection 72 (optionally via the fixture 74) of the shipping container 10′. The crane or hoist is operated to raise the lifting anchor element 52 to a height at which the rigging lines 56 are drawn taut without actually lifting the shipping container 10′. The winch 54 is then operated to draw the winch cabling 58 taut, again without actually lifting the shipping container 10′. Thereafter, the crane or hoist operates to continue raising the lifting anchor element 52 and the integral or connected winch 54. Since the rigging lines 56 and winch cabling 58 are both taut at the start of this lifting operation, the result is to lift the shipping container 10′ upward while keeping the shipping container 10′ in its horizontal position. This lifting is continued until the raised shipping container 10′ has sufficient ground clearance to be rotated about the lateral lifting features 70 into the vertical position about the without hitting the ground. At this point, the lifting operation is terminated and the winch 54 is operated to draw in (i.e. shorten) the winch cabling 58. This operates to rotate the shipping container 10′ about the lateral lifting features 70 by raising the upper end of the shipping container 10′. The winch is thus operated until the vertical position shown in FIG. 8 is achieved. Transitioning from the vertical position (FIG. 8) to the horizontal position (FIG. 7) is as follows. The process again starts with connecting the lower ends of the rigging lines 56 to the lateral lifting features 70 of the shipping container 10′, and connecting the lower end of the winch cabling 58 to the top connection 72 (optionally via the fixture 74) of the shipping container 10′. The crane or hoist is operated to raise the lifting anchor element 52 to a height at which the rigging lines 56 are drawn taut without actually lifting the shipping container 10′. The winch 54 is then operated to draw the winch cabling 58 taut, again without actually lifting the shipping container 10′. Thereafter, the crane or hoist operates to continue raising the lifting anchor element 52 and the integral or connected winch 54. Since the rigging lines 56 and winch cabling 58 are both taut at the start of this lifting operation, the result is to lift the shipping container 10′ upward while keeping the shipping container 10′ in its vertical position. In this case, because the shipping container 10′ has its lowest extent when it is in the vertical position, the lifting can be brief, i.e. just enough to lift the vertically oriented shipping container 10′ off the ground. At this point, the lifting operation is terminated and the winch 54 is operated to let out (i.e. lengthen) the winch cabling 58. This operates to rotate the shipping container 10′ about the lateral lifting features 70 by lowering the upper end of the shipping container 10′. The winch is thus operated until the horizontal position shown in FIG. 7 is achieved. In the illustrative embodiment of FIGS. 7 and 8, it will be noted that the lateral lifting features 70 are not at the center of the length of the shipping container 10′, but rather are slightly closer to the lower end versus the upper end. As seen in FIG. 7, this has the effect that the rigging lines 56, when drawn taut, are not precisely vertical but rather are angled toward the lower end of the shipping container 10′ at a small angle off vertical. This has the advantage of reducing the winch force needed to initiate the rotation of the horizontal shipping container 10′ toward the vertical position. While this provides some mechanical benefit, the up-ender would also work with the lateral lifting features at the center of the length of the shipping container, or even with the lateral lifting features shifted slightly toward the upper end of the shipping container. In an alternative embodiment for reducing the force needed to rotate the shipping container, the lifting anchor element 52 can be replaced by a second winch so that the rigging lines 56 become secondary winch cabling whose length can be adjusted. In this variant embodiment, going from the horizontal to the vertical position can be achieved by first letting out some line on the secondary winch cabling so as to lower the bottom end of the shipping container, and then drawing in the (primary) winch cabling 58 to raise the top end of the shipping container. In this approach, however, care must be taken to ensure the crane or hoist is lifted high enough prior to the rotation operation to provide sufficient ground clearance to accommodate the lowering of the bottom end of the shipping container during the rotation. The lateral lifting features 70 can have the form of an eyehole, as shown, or can have a more complex configuration that promotes easy rotation of the shipping container about the lateral lifting features, for example by including a swivel element. The illustrative embodiments include two lateral lifting features 70 connected at opposite sides of the shipping container 10′. This arrangement advantageously provides a balanced pivot axis for rotating the shipping container 10′ between vertical and horizontal. More generally, however, at least one lifting connection 70 is connected at some point along the shipping container 10′. For example, a single rigging line 56′ (indicated by a dashed line only in FIG. 7) could pivotally connect with an upper surface of the (horizontally oriented) shipping container. In this case, it would not be possible to rotate the shipping container into a precisely vertical position since the single rigging line 56′ would impinge on the shipping container; however, it would be possible to achieve a nearly vertical orientation which might, for example, be sufficient to then lower the shipping container into the loading stand 40 of FIG. 6. The winch 54 can be located anywhere along the winch cabling 58, and in some embodiments it is contemplated to integrate the winch into the fixture 74 proximate to the upper end of the shipping container. Note that in this case, the winch is connected with the lifting anchor element when the winch cabling is taut such that operating the crane or hoist to raise (lower) the lifting anchor element also raises (lowers) the winch together with the lifting anchor element. An advantage of the lift-based up-ender 50 is that the shipping container (in either its horizontal or vertical position) can be moved laterally using the crane or hoist. This can reduce operations. For example, to place a newly shipped container into the loading stand 40 of FIG. 6, a conventional process would employ a dedicated up-ender apparatus to up-end the shipping container into the vertical position, followed by connection of a separate crane to the vertically oriented shipping container to lift and laterally move the vertical shipping container. By contrast, the lift-based up-ender 50 can lift the horizontal shipping container, rotate it to vertical, and then move it laterally without placing it back onto the ground. Alternatively, the shipping container could be moved laterally into a desired position and then rotated to the vertical if advantageous to do so (e.g., based on available space clearances for the lateral transport). While illustrated operating on the shipping container 10′, more generally the disclosed up-ender 50 can be used with substantially any type of unirradiated fuel shipping container that is to be rotated between horizontal and vertical positions, so long as the lifting connections 70 and top connection 72 can be made to the shipping container. Thus, the lift-based up-ender 50 can also be used with a clamshell-type shipping container or other type of unirradiated fuel shipping container. The present disclosure has been described with reference to exemplary embodiments. Obviously, modifications and alterations will occur to others upon reading and understanding the preceding detailed description. It is intended that the present disclosure be construed as including all such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.
054208971	description	DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a structure of a fast reactor according to one embodiment of the present invention. The fast reactor 60, shown in FIG. 1, is provided with a core 61 composed of fuel assemblies packed with nuclear fuels and the core 61 has a substantially columnar shape in an entire structure. The outer periphery of the core 61 is surrounded by a core barrel 62 for protecting the same and an annular reflector 63 is disposed outside the core barrel 62 so as to surround the same. A partition wall structure 65 is disposed outside the reflector 63 so as to surround the reflector 63 and to define an inner wall of a coolant passage 64 for a primary coolant. An outer wall of the coolant passage 64 is defined by a reactor vessel 66 outside the partition wall structure 65. A neutron shield 67 is disposed in the coolant passage 64 so as to surround the core 61. The outside of the reactor vessel 66 is guarded by a guard vessel 68. The reflector 63 is suspended by a plurality of driving shafts 70 penetrating an upper plug 69 to be vertically movable by means of a reflector driving mechanism 71. The partition wall structure 65 extends upwards, as viewed, from a base plate 72 on which the core 61 is mounted and forms the annular coolant passage 64 between it and the reactor vessel 66. The neutron shield 67 is disposed below this coolant passage 64 as mentioned above. An annular electromagnetic pump 73 is arranged in the coolant passage 64 above the neutron shield 67 and an intermediate heat exchanger 74 is arranged further above the electromagnetic pump 73. A decay heat removal coil means 75 is disposed further above the intermediate heat exchanger 74. The electromagnetic pump 73 and the intermediate heat exchanger 74 are composed integrally with each other and the integral structure is further integrally and continuously formed with the upper structure of the reactor. As shown in FIG. 1, the intermediate heat exchanger 74 has a tube side through which the primary coolant passes and a shell side through which the secondary coolant passes. A seal bellows 76 is disposed between the lower end of the integral structure of the electromagnetic pump 73 and the intermediate heat exchanger 74 and the upper end of the partition wall structure 65 for absorbing expansion or contraction of a small sized fast reactor due to the heat and defining the coolant passage 64. The reactor of FIG. 1 uses a nuclear fuel containing plutonium for the core 61. In the actual operation of the reactor, the plutonium is fissioned and generates heat, and simultaneously, excessed fast neutrons are absorbed by a depleted uranium, thus producing plutonium of an amount more than that to be burned up. The reflector 63 reflects the neutrons irradiated from the core 61 to thereby facilitate burn-up and breeding of the nuclear fuel in the core 61. The reflector 63 is gradually moved vertically in accordance with the progress of the burn-up of the fuel with the criticality of the fuel maintained, and accordingly, a new portion of the fuel in the core 61 is then gradually burned up, thus keeping the burn-up for a long time. In the actual operation, liquid sodium as the primary coolant is filled up in the reactor vessel 66, and the heat generated in the core 61 is taken out externally while cooling the core 61 by the primary coolant. The primary coolant flows in the following fashion. Solid line arrows in FIG. 1 represent the flow direction of the primary coolant, and as shown by these arrows, the primary coolant moves downward by the actuation of the electromagnetic pump 73 to the bottom of the reactor vessel 66 through the inside of the neutron shield 67. Next, the primary coolant passes the inside of the core 61 upward and enters into the tube side of the intermediate heat exchanger 74 at the upper portion of the reactor vessel 66. The primary coolant performs the heat exchanging operation with the secondary coolant in the intermediate heat exchanger 74, then flows outward and is further moved downward by the operation of the electromagnetic pump 73. The secondary coolant flows into the shell side of the intermediate heat exchanger 74 through an inlet nozzle 77 and is heated by the primary coolant through the heat exchanging operation. Thereafter, the secondary coolant is flown out from the intermediate heat exchanger 74 through an outlet nozzle 78 and the heat of the secondary coolant is then converted to a dynamic power for other use. Referring to FIG. 2, it will be found that six driving shafts 70, in this embodiment, are arranged with equal distances from the central portion of the driving shaft arrangement. Inner and outer shells 79 and 80 of the intermediate heat exchanger 74 are positioned outside the driving shafts 70, and heat transfer tubes 81 are disposed between these inner and outer shells 79 and 80. The intermediate heat exchanger 74 and the electromagnetic pump 73 are both integrally suspended by an outer shroud 82. As can be seen from FIGS. 1 and 2, in this embodiment, the intermediate heat exchanger 74 has an annular configuration and the reflector 63 and the driving shafts 70 are arranged inside the intermediate heat exchanger 74 in which the driving shafts 70 are arranged at portions apart from the central portion so as not to be interferred with the core 61. Namely, the upper portion of the core 61 in the reactor vessel 66 is a vacant space, and accordingly, the core 61 can be exchanged for an inspection or other purpose without removing the electromagnetic pump 73 and the intermediate heat exchanger 74. FIG. 3 shows the cross sectional view of the fast reactor of FIG. 1 taken along the line III--III, and referring to FIG. 3, the core 61 has an entirely circular cross section and the core barrel 62 is disposed outside the core 61. The annular reflector 63 is further disposed outside the core barrel 62 and suspended by the driving shafts 70. The partition wall structure 65 is arranged outside the reflector 63 and a plurality of ribs 83 are provided to the inside portion of the partition wall structure 65 so as to project radially inward of the fast reactor 60. These ribs 83 penetrate the reflector 63 and support the outer peripheral portion of the core barrel 63 at their distal end portions. The reflector 63 is divided into six sections as shown which are suspended by the driving shafts 70, respectively, to be vertically movable without being interferred with the ribs 83. As shown in FIG. 3, the neutron shield 67 having an entirely annular structure is arranged to an outer periphery of the partition wall structure 65 so that a plurality of columns 84 are arranged with spaces from each other. According to such arrangement, the primary coolant passes inside the neutron shield 67 to effectively cool the neutron shielding member 67. This embodiment of the structure and arrangement described above will operate as follows. Since the reflector 63 of this embodiment is arranged closely to the outer periphery of the core 61, the neutrons can be effectively reflected, whereby the burn-up and breeding of the fuel can be effectively carried out, and in accordance with the progress of the burn-up of the fuel, the reflector 63 can be gradually moved vertically with the criticarity maintained, so that the new fuel portion of the core 61 is burned up gradually continuously, thus keeping the burn-up for a long time. The neutron shield 67 shields the neutrons passing or going round the reflector 63 to thereby reduce an amount of neutrons emitted in the space in the reactor vessel 66 and the shielding structure. According to this fact, stainless steel can be used as the constructional material for the reactor vessel 66, thus achieving an economical advantage. Furthermore, since the heat and gas such as argon and nitrogen to be activated in the shielding structure can be reduced in amounts, the cooling equipment of the shielding structure can be made compact in small size, thus alleviating a sealing requirement with respect to the activated argon and nitrogen. Furthermore, since the reflector 63 and the neutron shield 67 are dipped in the primary coolant, the heat generated by the reflector can be effectively utilized as power of the fast reactor 60, thus realizing a more effective fast reactor. Still furthermore, in this embodiment, since the electromagnetic pump 73 is disposed downstream side of the intermediate heat exchanger 74, the primary coolant driven by the electromagentic pump 73 has the lowest temperature in the primary coolant circulation cycle. Accordingly, thermal strain to be applied to the electromagnetic pump 73 is very small and the electromagnetic pump 73 has an excellent durability for a long time use, resulting in the elongation of the life time of the fast reactor itself. Still furthermore, since the electromagnetic pump 73 and associated members are disposed above the core 61 without being interferred with the core, at a core exchanging time, the used core 61 can be taken out from the reactor vessel 66 by removing the upper plug 69 and directly drawing vertically upward the core 61 externally. This eliminates the removing working of the intermediate heat exchanger 74 and the electromagnetic pump 73, which working is not neglected in the conventional structure of the fast reactor, for the fuel exchanging operation, thus obviating damage or breakage of the electromagnetic pump 73 or other members during the fuel exchanging operation. It is to be noted that, in this embodiment, the core 61, the core barrel 62, the reflector 63, the partition wall structure 65, the neutron shield, the reactor vessel 66 and the guard vessel 68 are arranged respectively outside apart from the central portion of the fast reactor 60, and the coolant passage 64 is formed between the partition wall structure 65 and the reactor vessel 66, but as can be understood from the above description, the following structures are within the scope or range of the present invention; that is, the structure in which the reflector 63 are radially divided into a plurality of reflector sections and the divided reflector sections are axially movably supported; the structure in which the neutron shield 67 is composed of a plurality of columns or multi-structured annular wall member having gaps through which the primary coolant passes; the structure in which the annular electromagnetic pump 73 and the intermediate heat exchanger 74 are disposed in the upper portion of the coolant passage 64 and the reflector 63 is suspended inside the electromagnetic pump 73 and the intermediate heat exchanger 74; and the structure in which the electromagnetic pump 73 and the intermediate heat exchanger 74 are integrally formed with the upper structure of the reactor and the seal bellows 76 is disposed between the lower end of the integral structure and the upper end of the partition wall structure 65 standing on the lower structure of the reactor. FIG. 4 is a second embodiment of the present invention which is applied to an incore reflector type sodium cooling small-sized fast reactor having a core equivalent diameter of about 83 cm and an effective length of about 400 cm, and there is utilized a neutron reflector made of stainless steel having a length of about 170 cm and a thickness of about 15 cm. A core 91 is disposed at the central portion inside the reactor vessel 90 and a neutron shield 92 is disposed so as to surround the periphery of the core 91. The inside of the reactor vessel 90 is filled up with a coolant 93 such as liquid sodium. The core 91 is composed of eighteen fuel assemblies of, for example, hexagonal shape and a channel, not shown, for a neutron absorbing rod to be withdrawn upward in an operation period for reactivity control of the core 91 is arranged at the central portion of the hexagonal arrangement and surrounded by a core barrel, not shown. Outside this core barrel, a partition wall structure, not shown, for sectioning the passage of the coolant 93 is arranged apart from the core barrel with a predetermined distance and an area 95 for moving the neutron reflector 94 utilized for the operation of the core 91 is defined by the space between the core barrel and the partition wall structure. A neutron absorber 85 formed of such as natural boron degraded in neutron reflecting ability in comparison with the coolant 93 and having substantially the same cross section as that of the neutron reflector 94 is disposed above the neutron reflector 94 so as to provide a continuous structure thereof. The neutron absorber 85 has an upper end portion to which a lower end portion of a driving rod 96 is connected. According to such structure, the driving rod 96 is vertically moved by the operation of a driving mechanism 98 and, hence, the neutron reflector 94 and the neutron absorber 85 are integrally moved vertically in the moving area 95 between the core barrel and the partition wall structure. This second embodiment will operate as follows. First, there will be described the changing of the reactivity in a case where the neutron reflector 94 and the neutron absorber 85 are moved upward from the positional relationship shown in FIG. 5A to that shown in FIG. 5B. At this time, it is of course natural that the reactivity is increased by the changing of the relative positional relationship between the neutron reflector 94 and the core 91, but the changing of the reactivity is caused by the fact that an area surrounded by the coolant in the core and an area surrounded by the neutron absorber 85 are different from each other. Namely, referring to FIG. 5A, the outer periphery of the core 91 is surrounded by the coolant 93 at the area having a length L1 and by the neutron absorber 85 at the area having a length L2. On the other hand, referring to FIG. 5B, the outer periphery of the core 91 is surrounded by the coolant 93 at the area having a length L3 and by the neutron absorber 85 at the area having a length L4. Accordingly, in the positional relationship in FIG. 5B, the area surrounded by the coolant 93 is increased by an area corresponding to the length a (L3-L1=L2-L4=a) and the area surrounded by the neutron absorber 84 is decreased by an area corresponding to the length a in comparison with the positional relationship of FIG. 5A. Accordingly, the difference in the neutron reflecting ability between the neutron absorber 84 and the coolant 93 of this area having the length a is added to the reactivity on the side surface of the core 91. FIG. 6 shows a state of the beginning of life (BOL) at which the neutron reflector 94 is positioned at the lower portion of the core 91. In this state, the periphery of the core 91 is surrounded by the neutron absorber 85, rather than the coolant 93, which is degraded in the neutron reflecting ability in comparison with the coolant 93, so that the reactivity can be suppressed to a low value in comparison with a prior art structure in which the core is surrounded by the coolant. Thus, the enrichment of the fuel can be enhanced by an extent corresponding to the suppressed reactivity to thereby distribute the elongation of the reactivity life time of the core 91. In this case, it is preferred to surround the entire periphery of the core 91 by the neutron absorber 85. FIG. 7 represents a third embodiment of the fast reactor according to the present invention. Referring to FIG. 7, in this embodiment, vacuum condition or air filling condition having a neutron reflecting ability less than that of the coolant 93 is utilized in place of the neutron absorber 85 in the former embodiment. Namely, as shown in FIG. 7, a sealed space 87 is defined by a box-like member 86 above the neutron reflector 94 and this space 87 is made vacuum or filled up with gas. For the comparison of the effects attained by the structures of the above two embodiments with those attained by the conventional structure, the resulted reactivity lives of burn-up calculations of the cores of these structures are shown in the following table. ______________________________________ Effects to Reactivity Life Reactivity Life Relative Value ______________________________________ Reflector Upper Portion about 6 years 1 Coolant (Prior Art) Natural Boron about 10 years 1.7 (Second Embodiment) Vacuum or Gas about 10 years 1.7 (Third Embodiment) ______________________________________ It will be seen from this table that the reactivity life of the core can be expanded about 1.5 time according to the embodiments of the present invention in comparison with the conventional example. In the respective embodiments, since the neutron reflector 94 and a substance having a neutron reflecting ability less than that of the coolant 93 disposed above the reflector 94 are vertically moved integrally, it is necessary to provide a space for accommodating the substance above the core 91. However, it is difficult to provide such space in a narrow interior of the reactor vessel in the point of the core structure. FIG. 8 represent a fourth embodiment which substantially eliminates the above defect. In this fourth embodiment, a guide box 88 having approximately U-shape in section with a downward opening and extending along substantially an entire axial length of the core 91 is fixedly arranged in a moving area 95 on the side of the core 91. The upper end portion of the guide box 88 is communicated with a cover gas space 99 above the level of the coolant 93 through a communication tube 89 and a sealing bellows 59 is disposed between the upper end portion of the neutron reflector 94 and an upper portion of the inner peripheral surface of the guide box 88. According to such structure, the neutron reflector 94 moves vertically inside the guide box 88 and a cover gas is introduced into the cover gas space 99 above the guide box 88. A boundary between the introduced cover gas and the coolant can be sealed by the sealing bellows 59. A driving rod 96 is connected to the upper end portion of the neutron reflector 94 so as to extend in the communication tube 89. For example, other sealing means such as metal ring may be utilized in place of the sealing bellows 59. In this fourth embodiment, the guide box 88 is fixed with respect to the core 91, and when an inner volume of the guide box 88 is reduced in accordance with the lift-up of the neutron reflector 94, the coolant 93 of the amount corresponding to the reduced volume in the guide box 88 is supplied to a portion below the neutron reflector 94. FIG. 9 represents a fifth embodiment of the fast reactor according to the present invention, which differs from the fourth embodiment in a structure such that the communication tube 89 extends further upwards externally of the reactor vessel 90 through a shielding plug 97 so that the gas is introduced into the inner space of the guide box 88 from the upper end opening of the extended communication tube 89 and that the bellows 59 is removed in this fifth embodiment. According to the fifth embodiment, a pressure inside the guide box 88 can be controlled from the outside of the reactor vessel 90, and hence, the surface level of the coolant 93 below the neutron reflector 94 can be optimumly adjusted. FIG. 10 shows a sixth embodiment of the fast reactor according to the present invention, which is provided commonly with the characteristic features of the fourth and fifth embodiments mentioned above. Namely, in the structure of the sixth embodiment, the communication tube 88 extends upwards externally of the reactor vessel 90 through the shielding plug 97 to thereby introduce the gas from the outside of the reactor vessel 90 into the guide box 88 and the sealing bellows 59 is disposed between the upper end portion of the neutron reflector 94 and the upper portion of the inner peripheral surface of the guide box 88 to thereby seal the boundary between the gas externally introduced into the guide box 88 and the bellows 59. FIG. 11 shows a structure of the fast reactor according to a seventh embodiment of the present invention, in which a fast reactor 100 is provided with a reactor vessel 101 in which a core is accommodated. A reactor containment vessel 102 is substantially entirely formed of concrete to define an inner space which defines a reactor vessel chamber 103 in which the body of the reactor vessel 101 is accommodated and a reactor upper chamber 105 in which a containment dome 104 covering the upper portion of the reactor vessel 101 is accommodated. A stepped portion is formed at a boundary portion between the reactor upper chamber 105 and the reactor vessel chamber 103, the stepped portion constituting a core support portion for supporting the reactor vessel 101. The reactor vessel 101 is fixed on a reactor support ring 107 fixed on the reactor support portion or structure 106 to be vertically, as viewed in an installed condition, thermally expandable and contractable with the reactor support ring 107 being its center. Inside the concrete wall structure of the reactor containment vessel 102, there are disposed an air supply duct 108 communicated with the upper portion of the core upper chamber 105 and an exhaust duct 109 communicated with the upper portion of the reactor vessel chamber 103. A reactor vessel air cooling cylinder 110 is arranged so as to surround the outer peripheral wall of the reactor vessel 101 with a space therefrom. The air cooling cylinder 110 has an upper end portion connected to the upper portion of the reactor vessel 101 and a lower end portion opened to the lower space of the reactor vessel chamber 103. As clealy shown in FIG. 12, to an upper portion of the reactor vessel air cooling cylinder 110, there is disposed an exhaust bellows 111 having one end connected to the exhaust duct 109 and other end communicated with the inside space of the reactor vessel cooling cylinder 110. Further, as shown in FIG. 12, the reactor support ring 107 is formed with a cylindrical portion 107a having a predetermined height and the cylindrical portion 107a is punched with a plurality of through holes 112 through which air flows. The seventh embodiment of the structure described above and shown in FIGS. 11 and 12 will operate in the following manner. The fast reactor 100 of this embodiment contains a core, not shown, composed of a plurality of fuel assemblies. Heat is generated by fission of the fuel in the core and the heat is taken out externally through the heat exchanging operation between the primary coolant and the secondary coolant to thereby convert the heat into dynamic power. Accordingly, during the operation or running of the core, the reactor vessel 101 is heated highly and it is hence necessary to continuously cool the reactor vessel 101. The arrows in FIGS. 11 and 12 show the flow direction of the cooling air. As shown in FIG. 11, the cooling air flows into the reactor upper chamber 105 from the air supply duct 108 through a filter 113, then flows into the reactor vessel chamber 103 through the through holes 112 of the reactor support ring 107, then rises in an air passage between the reactor vessel cooling cylinder 110 and the reactor vessel 101 and is exhausted into an external space through the exhaust bellows 111 and the exhaust duct 109. Such air flowing can be made in combination of forcible air flowing and natural air flowing. In such operation, the space defined between the outside of the reactor vessel air cooling cylinder 110 and the inner wall of the reactor vessel chamber 103 constitutes a low temperature air passage L and the space defined by the inside of the reactor vessel air cooling cylinder 110 and the outside of the reactor vessel 101 constitutes a high temperature air passage H. The cooling air flows into the low temperature air passage L of the reactor vessel chamber 103 while cooling the reactor support portion 106 after passing the reactor upper chamber 105. In the low temperature air passage L, the air flows while shutting down the heat transfer between the wall surface of the reactor vessel chamber 103 and the high temperature air passage H. Subsequently, the air flows into the high temperature air passage H through the lower end portion of the reactor vessel air cooling cylinder 110 and rises in the high temperature air passage H while cooling the reactor vessel 101. The high temperature air reaching an air exhaust portion Ha at the upper end portion of the high temperature air passage H is discharged to the exhaust duct 109 through the exhaust bellows 111 without applying thermal affect on the reactor support ring 107 and the reactor support portion 106. According to the air flow route described above, the reactor support portion 106 and the reactor support ring 107 are positioned to an air introducing portion La of the low temperature air passage L to thereby always be cooled by the low temperature air and the high temperature air after finishing the cooling is exhausted without heating the reactor support portion 106 and the reactor support ring 107, so that the reactor support portion 106 can be surely maintained with a low temperature, thus improving the safeness and reliability of the reactor. Furthermore, since it is not necessary to locate specific equipment or heat insulating material such as local cooler for locally cooling the reactor support portion 106, the fast reactor 100 having a simple structure can be realized. Further, it is to be noted that the basic conception of the present invention resides in that the high temperature and low temperature air passages are formed inside and outside of the reactor vessel air cooling cylinder, the reactor support portion is disposed in the air flow-in portion of the low temperature air passage and the air exhaust means for exhausting the high temperature air is disposed at the end portion of the high temperature air passage, and accordingly, the locations or positions of the air supply duct and the exhaust duct and the concrete structure of the air exhaust means are not limited to the embodiments described above. An eighth embodiment of the present invention in which the air supply duct is connected to the through hole of the reactor support ring will be described hereunder with reference to FIG. 13. Referring to FIG. 13, the air supply duct is directly connected to the through hole of the reactor support ring and like reference numerals are added to elements or members corresponding to those shown in FIG. 11 and the detailed description thereof are omitted herein. In the embodiment of FIG. 13, the reactor support ring 114 is embedded in a concrete of the reactor containment vessel 102 at a portion above the reactor vessel chamber 103 and an air introducing hole 115 is formed to a predetermined portion of a cylindrical portion 114a of the reactor support ring 114. An air supply duct 116 is formed in the wall structure of the concrete in a manner such that an outlet of the air supply duct 116 alines with the through hole 115. According to this embodiment, since the cooling air first cools, without being heated, the reactor support ring 114, the reactor support portion 106 can be effectively maintained with its low temperature due to good heat radiation property of metal material of the reactor support ring 114. FIGS. 14 to 16 represent a neutron absorbing rod driving mechanism having high safety structure in which a neutron absorbing rod is not attracted to a neutron absorbing rod holding rod by means of an electromagnet till a time when the temperature of the coolant reaches a predetermined temperature such as 350.degree. C. and, accordingly, it is prevented to erroneously draw out the neutron absorbing rod from the core in a temperature area having a large temperature compensation reactivity. The neutron absorbing rod 120 has an upper end portion connected to the neutron absorbing rod holding rod 121 through the electromagnet 124 and extends axially perpendicularly so as to be inserted into the central portion of the core 61. The neutron absorbing rod 120 is inserted into the core 61 at the reactor shut-down time, but it is to be withdrawn therefrom at the reactor operation time. However, because the temperature compensation reactivity is large till the time when the coolant is preheated to the temperature of 350.degree. C., it is necessary to construct the neutron absorbing rod 120 not to be withdrawn from the core 61. Namely, till the time of the temperature rising of 350.degree. C., the neutron absorbing rod 120 has to be constructed not to be attracted to the neutron absorbing rod holding rod 121 by the electromagnet 124. As shown in FIG. 14, the neutron absorbing rod holding rod 121 is arranged above the neutron absorbing rod 120, and the electromagnet composed of a coil 122 and an iron core 123 is secured to the lower end portion of the neutron absorbing rod holding rod 121. A guide 125 is formed to these members so as to axially penetrate the neutron absorbing rod holding rod 121 and the electromagnet 124 for positioning these elements. The lower end portion of the guide 125 is formed sharply in section so as to abut against a recess formed to the upper end surface of the neutron absorbing rod 120. In the described embodiment, a thermal expansioncoeffcient of the neutron absorbing rod holding rod 121 is made larger than that of the guide 125 so that the distance between the lower end of the electromagnet 124 and the lower end of the guide 125 is made small, in comparison with the time of low temperature shut-down time (200.degree. C.), when the temperature of the coolant reaches 350.degree. C. at thereactor operation starting time. The difference in the thermal expansion coefficients will be achieved by changing a substance of the neutron absorbing rod holding rod 121 from that of the guide 125. In one example, the neutron absorbing rod holding rod 121 will be made of stainless steel and the guide 125 will be made of Md.9Cr-1Mo. According to such structure, the neutron absorbing rod 120 is not attracted to the electromagnet 124 till the time when the coolant temperature reaches 350.degree. C. from 200.degree. C., shut-down time, and upon reaching 350.degree. C., the neutron absorbing rod 120 is attracted to the electromagnet 124. This fact will be explained hereunder in accordance with the actual operation. Namely, supposing the absorbing limit width of the electromagnet 124 being .alpha.(mm), the distance from the lower end of the electromagnet 124 to the lower end of the guide 125 at a certain temperature being X(mm) and the height of the recess of the upper surface of the neutron absorbing rod 120 being h(mm), in a case where condition of the following equation (1) is satisfied, the neutron absorbing rod 120 never be attracted by the electromagnet 124. EQU X-h>.alpha. (1) When the coolant temperature reaches 350.degree. C., the neutron absorbing rod 120 is attracted by the electromagnet 124, so that the distance X1 from the lower end of the electromagnet 124 to the lower end of the guide 125 satisfies the following equation (2) as shown in FIG. 16. EQU X1=h+.alpha. (2) Supposing the distance from the lower end of the electromagnet 124 to the lower end of the guide 125 at the temperature of 200.degree. C. being X0(mm) and supposing that the distance X0(mm) changes to the distance X1(mm) till the time when the temperature of the coolant increases from 200.degree. C. to 350.degree. C., the difference d(mm) in the thermal expansion amounts between the neutron absorbing rod holding rod 121 and the guide 125 is expressed as the following equation (3). EQU d=X0-X1 (3) Accordingly, as shown in FIG. 14, the distance X0 from the lower end of the electromagnet 124 to the lower end of the guide 125 at the low temperature shut-down time (200.degree. C.) is expressed as the following equation (4). EQU X0=X1+d=h+.alpha.+d (4) According to the structure having the positional relationship described above, the neutron absorbing rod 120 never be attracted by the electromagnet 124 till the time of reaching the temperature of 350.degree. C. from 200.degree. C. (low temperature shut-down time) as shown in FIG. 14. Upon reaching 350.degree. C., as shown in FIG. 16, the distance between the lower end of the electromagnet 124 and the upper surface of the neutron absorbing rod 120 becomes .alpha.(mm) being the absorption limit width, and when the temperature of the coolant becomes more than 350.degree. C., as shown in FIG. 15, the electromagnet 124 attracts the neutron absorbing rod 120. The above structural feature will be explained in detail by way of concrete numerals. The neutron absorbing rod holding rod 121 made of stainless steel has a thermal expansion coefficient of 18.times.10.sup.-6 mm/mm .degree.C. (350.degree. C.) and the guide 125 made of Md.9Cr-1Mo has a thermal expansion coefficient of 12.times.10.sup.-6 mm/mm .degree.C. (350.degree. C.). The neutron absorbing rod holding rod 121 used for a vertically elongated type reactor vessel has about 10 m length. Accordingly, when the coolant temperature increases from 200.degree. C. to 350.degree. C., the difference d(mm) due to the thermal expansion is expressed as follows. EQU d=(18-12).times.10.sup.-6 (mm/mm .degree.C.).times.(350-200) (.degree.C.).times.10000(mm)=9(mm). (5). Accordingly, in the case of 200.degree. C. of the coolant temperature (low temperature shut-down time), the distance X0 from the lower end of the electromagnet 124 to the lower end of the guide 125 is expressed as the following equation (6). EQU X0=h+.alpha.+d=h+.alpha.+9(mm) (6) Accordingly, in the present embodiment, the distance between the lower end of the electromagnet 124 and the upper end of the neutron absorbing rod 120, at the low temperature shut-down time, is set to a distance obtained by adding the absorbing limit width .alpha.(mm) of the electromagnet 124 to the difference due to the thermal expansion between the neutron absorbing rod holding rod 121 and the guide 125. Because of this reason, at the low temperature shut-down time, the electromagnet 124 does not attract the neutron absorbing rod 120, and accordingly, even if the neutron absorbing rod holding rod 121 be erroneously moved upward, the neutron absorbing rod 120 is never withdrawn from the core. Therefore, the neutron absorbing rod is not also withdrawn erroneously from the core in the temperature range having large temperature compensation reactivity, thus improving the safeness of the reactor. Furthermore, this safeness compensation operation is performed by utilizing the nature characteristic, i.e. thermal expansion, of the structure without depending on any mechanical operation, thus achieving higher reliability. Further, it is to be noted that the present invention is not limited to the described embodiments and many other changes or modifications may be made. Particularly, the substances of the neutron absorbing rod holding rod and the guide are not limited to ones described hereinbefore. For example, the substance of the guide 125 may be substituted with ferite steel, which has thermal expansion coefficient of 11.times.10.sup.-6 mm/mm .degree.C. (350.degree. C.) almost equal to that of the Md.9Cr-Mo, thus substantially the same effects being expected. FIG. 17 shows an arrangement of a nuclear power plant having a steam generator and being capable of roughly regulating power control of a fast reactor by displacing a neutron reflector arranged so as to surround the outer periphery of the core and capable of finely regulating the power of the fast reactor by regulating feed water flow rate to the steam generator. Referring to FIG. 17, the power plant 130 is provided with a fast reactor 131 in which a core 132 is accommodated. A reflector 133 for maintaining a fission chain reaction of the core 132 by reflecting neutron fluxes radiated from the core 132 is disposed so as to surround the outer periphery of the core 132. The reflector 133 is driven vertically movably by a reflector driving mechanism 134. The reflector driving mechanism 134 is operated by a generator 135 of the power plant 130 so as to move upward the reflector 133 with a predetermined moving speed during the plant running period, thus performing the rough regulation of the power of the power plant 130. During the running period of the power plant, liquid sodium constituting a primary coolant fills inside the fast reactor 131 as well as the core 132 and the primary coolant is heated by the fission chain reaction of the core 132 and fed to an intermediate heat exchanger 137 through a primary coolant high temperature side line 136. In the intermediate heat exchanger 137, the primary coolant carries out a heat exchanging operation with a secondary coolant such as liquid sodium passing the intermediate heat exchanger 137, thus the second coolant being heated through the heat exchanging operation. The primary coolant of low temperature after the heat exchanging operation circulates again to the fast reactor 131 through the primary coolant low temperature side line 138. This circulation of the primary coolant is carried out by the actuation of a primary coolant circulation pump 139. The secondary coolant heated by the primary coolant in the intermediate heat exchanger 137 is fed to a steam generator 141 as a load heat exchanger through a secondary coolant high temperature side line 140 to thereby heat water fed in the steam generator 141. The secondary coolant of low temperature after the heat exchanging operation in the steam generator 141 circulates again to the intermediate heat exchanger 137 through a secondary coolant low temperature side line 142. This circulation of the secondary coolant is carried out by the actuation of a secondary coolant circulation pump 143. The water of high temperature after the heat exchanging operation in the steam generator 141 changes into steam, which is then fed to a turbine 145 through a steam line 144 and utilized to drive the turbine 145. The water feed to the steam generator 141 is performed by a water feed pump 146 through a water feed line 146a and a feed water flow rate is adjusted by a flow rate regulating valve 147. The nuclear power plant of FIG. 17 has a control system or unit of the structure described hereunder and a controlling method thereof is also described hereunder. An approximate power of the power plant 130 of this embodiment is decided by the lift-up speed of the reflector 133 by means of the generator 135, and the fine regulation of the set power value in the power plant 130 is performed by a plant control system or unit 148. The plant control unit 148 is inputted with a steam temperature Ts at an outlet portion of the steam generator detected by a temperature detector 149, a steam flow rate Gs at the outlet portion of the steam generator detected by a flow rate detector 150, a steam pressure Ps at the outlet portion of the steam generator detected by a pressure detector 151, a feed water flow rate Gw detected by a feed water rate detector 152 and a set power value Wd set by a power setter 153, calculates adjustment value with respect to the feed water flow rate Gw, and then transmits a signal of an opening degree of a feed water flow rate regulating valve to the feed water flow rate regulating valve 147. The fine adjustment of the power of the fast reactor 131 can be performed, by adjusting the feed water flow rate to the steam generator 141, through the secondary coolant, the intermediate heat exchanger 137 and the primary coolant. FIG. 18 shows arrangement of the plant control unit 148, which is composed of a thermal power calculation section 148a, a thermal power control section 148b and a flow rate control section 148c. The thermal power calculation section 148a calculates the thermal power Ws of the steam generator 141 in response to inputted signals representing the steam temperature Ts, the steam pressure Ps and the steam flow rate Gs. The thermal power control section 148b carries out a linear calculation with respect to a deviation (Wd-Ws) between the set power value Wd from the power setter 153 as a thermal power control target value of the steam generator 141 and the thermal power Ws of the steam generator from the thermal calculation section 148a, and then sets a feed water flow rate signal Gd to the steam generator 141. The flow rate control section 148c is inputted with a feed water flow rate Gw and carries out a linear calculation with respect to a deviation (Gd-Gw) between the feed water flow rate Gw and the feed water flow rate signal Gd, whereby a signal Zd representing the opening degree of the feed water flow rate regulating valve and the signal Zd is then transmitted to the feed water flow rate regulating valve 147. The processings in the respective control and calculation sections of the plant control unit 148 are performed as follows. FIG. 19 is a flowchart showing the processing in the thermal power calculation section 148a. In Step 161, the steam temperature Ts, the steam pressure Ps and the steam flow rate Gs are inputted into the thermal power calculation section 148a. In the next Step 162, a steam enthalpy Hs at the outlet portion of the steam generator is calculated from the steam temperature Ts and the steam pressure Ps. In Step 163, an enthalpy rising Hi in the steam generator 141 is calculated by subtracting a predetermined feed water enthalpy Hw at the power operation period. In Step 164, the thermal power Ws of the steam generator 141 is calculated by the product of the enthalpy rising Hi and the steam flow rate Gs. FIG. 20 is a flowchart showing the processing in the thermal control section 148b. In Step 171, the set power value Wd of the power setter 153 as the contol target value of the steam generator 141 and the thermal power Ws calculated by the thermal power calculation section 148a are inputted into the thermal power control section 148b. In the next Step 172, a deviation (Wd-Ws) between the set power value Wd and the thermal power Ws of the steam generator 141 are calculated. With respect to this deviation, a linear calculation such as proportional, integral or differential calculation and the feed water flow rate signal Gd is accordingly set. FIG. 21 is a flowchart showing the processing in the flow rate control section 148c. In Step 181, the feed water flow rate Gw detected by the feed water flow rate detector 152 and the feed water flow rate signal Gw set by the thermal power control section 148b are inputted into the flow rate control section 148c. In the next Step 182, the deviation (Gd-Gw) between the feed water flow rate Gw and the feed water flow rate signal Gd is calculated, and with respect to this deviation, a linear calculation such as proportional, integral or differential calculation is performed, thus obtaining the feed water flow rate regulating valve opening degree signal Zd. This signal Zd is transmitted to the feed water flow rate regulating valve 147. This embodiment operates in the following manner. According to this embodiment, the power of the fast reactor 131 is almost controlled by the lift-up speed of the reflector 133 directly driven by the power of the generator 135, and according to this fact, such accident as excessive lift-up of the reflector 133 by a failure or erroneous operation of the control mechanism for driving the reflector 133 and application of the excessive reaction can be prevented. Further, structure of the driving mechanism and control circuit for driving the reflector 133 can be simplified, resulting in the realization of the compcat structure of the nuclear power plant itself. Furthermore, according to this embodiment, the fine adjustment of the power of the fast reactor 131 can be performed by controlling the feed water flow rate Gw for the steam generator 141. The controlling of the feed water flow rate Gw affects the temperature of the secondary coolant at the outlet side of the steam generator 141 through the heat exchanging operation of the steam generator 141 and further affects the temperature of the primary coolant at the inlet side of the fast reactor 131 through the secondary coolant and the intermediate heat exchanger 137. The temperature of the primary coolant at the inlet side of the fast reactor 131 affects the chain reaction of the core 132 of the fast reactor 131. According to this result, the power of the fast reactor 131 is automatically set to a value corresponding to the power of the steam generator 141. For example, when the set value of the thermal power of the steam generator 141 is raised by 10% of the rated power value, the feed water flow rate Gw is controlled to be increased. Accordingly, the temperature of the secondary coolant at the outlet side of the steam generator 141 descends, and hence, the temperature of the primary coolant at the inlet side of the fast reactor 131 also descends through the secondary coolant, the intermediate heat exchanger and the primary coolant. According to this result, a positive reactivity is applied to the core 132 due to the temperature feedback effect, the thermal power of the fast reactor 131 increases and the set value of the thermal power is adjusted to a value increased by 10% of the rated value corresponding to the thermal power of the steam generator 141. As described above, according to this embodiment of the present invention, since the power of the fast reactor 131 can be adjusted to a value corresponding to the set value of the thermal power of the steam generator 131 by controlling only the feed water flow rate Gw without operating the control rod, even in the failure of the plant control unit 148, the control rod is prevented from erroneously drawing out to apply the reactivity to the core, whereby the nuclear power plant can be safely and stably operated. Another embodiment of the nuclear power plant according to the present invention will be further described hereunder with reference to FIG. 22, in which like reference numerals are added to elements or units corresponding to those of the former embodiment of FIG. 17. Referring to FIG. 22, a fast reactor 154 contains a core 155 disposed at the inside lower portion of the fast reactor 154. A reflector 156 is arranged so as to surround the outer periphery of the core 155 and an intermediate heat exchanger 157 is disposed to an inside upper portion of the fast reactor 154. The reflector 156 is driven vertically as viewed by a driving mechanism, not shown. A primary coolant fills the inside of the fast reactor 154 and is driven by a primary coolant circulation pump 139a so as to pass the intermediate heat exchanger 157 through which a secondary coolant also passes to carry out the heat exchanging operation therein with the primary coolant. The secondary coolant is driven by a secondary coolant circulation pump 143 and circulates between the intermediate heat exchanger 157 and the steam generator 141. The feed water heated through the heat exchanging operation in the steam generator 141 changes into steam, which is then fed to the turbine 145 through the steam line 144 to thereby drive the turbine 145. In this embodiment, the revolution number of the turbine 145 is regulated to a predetermined number by a main steam governor 158 and the main steam pressure is controlled to a predetermined pressure by a turbine bypass valve 159. The steam driving the turbine 145 and the bypassed steam are condensed to water by a condenser 160, which is then recirculated by the operation of the feed water pump 146, and the feed water flow rate Gw is regulated by the feed water flow rate regulating valve 147. The power control of the fast reactor 154 at the running start time of the power plant will be explained hereunder with reference to the flowchart of FIG. 23. Referring to FIG. 23, in Step 191, the thermal power Ws of the steam generator 141 is calculated by the thermal power calculation section 148a. In the next Step 192, the power value Wd set by the thermal power control section 148b is inputted to obtain the deviation from the thermal power Ws. At the operation starting time, since the set power value Wd inputted into the thermal control section 148b rises at a constant rate of change, a deviation (Wd-Ws) is always caused between the set power value Wd and the thermal power calculated by the thermal power calculation section 148a. In Step 193, a linear calculation is effected to this deviation (Wd-Ws) and the feed water flow rate signal Gd is set so as to increase the thermal power of the steam generator 141. In Step 194, the feed water flow rate signal Gd and the feed water flow rate Gw are inputted into the flow rate control section 148c. In Step 195, the deviation (Gd-Gw) between the feed water flow rate signal Gd and the feed water flow rate Gw is obtained by the flow rate control section 148c, and with respect to this deviation, a linear calculation such as proportional, integral or differential calculation is effected, whereby the signal Zd of the opening degree of the feed water flow rate regulating valve so as to increase the fed water flow rate Gw. In Step 196, the set power value Wd after the control and the thermal power Ws are compared with each other, and in the case of NO (not equal), the above processes are repeated till the time when the set power value Wd becomes equal to the thermal power Ws. As described above, the affect of the increasing of the feed water flow rate Gw due to the feed water flow rate controlling operation performed so as to increase the thermal power Ws of the steam generator 141 in accordance with the increasing of the set power value Wd is realized as the lowering of the temperature of the secondary coolant at the outlet portion of the steam generator 141 and further realized as the lowering of the temperature of the primary coolant through the secondary coolant and the intermediate heat exchanger. According to the lowering of the temperature of the primary coolant, the reaction of the core 155 is activated and the power of the fast reactor 154 then increases. Such controlling operation is continued till the time when the set power value Wd becomes the rated set power value and the thermal power of the fast reactor 154 is adjusted to the rated value. Accordingly, without operating the control rod and by controlling only the feed water flow rate Gw, the power of the power plant can be increased to the rated value safely and stably. In the following, reactor burn-up compensation control and generator load follow-up control will be explained with reference to the above embodiment of the present invention. The reactor burn-up compensation control is explained by way of the flowchart of FIG. 24. Referring to FIG. 24, rough adjustment of the compensation of the burn-up degree of the core 155 is performed by drawing out the reflector with a predetermined speed, but due to the characteristics of the reflector 156, the power of the fast reactor 154 is not maintained completely constant and the power is somewhat increased or decreased. In Step 201, the thermal power Ws of the steam generator 141 is calculated, and in Step 202, when the thermal power Ws changes, the deviation (Wd-Ws) is caused between the set power value Wd and the thermal power Ws of the steam generator. In Step 203, the deviation (Wd-Wd) is calculated in the thermal power control section 148b and the feed water flow rate signal Gd is set. In the next Step 204, the feed water flow rate signal Gd and the feed water flow rate Gw are inputted and stored into the flow rate control section 148c by the flow rate control section 148c. In Step 205, the deviation (Gd-Gw) between the feed water flow rate signal Gd and the feed water flow rate Gw is obtained in the flow rate control section 148c and the flow rate regulating valve opening degree signal Zd is set through a linear calculation, and the feed water flow rate regulating valve is controlled. In Step 206, it is discriminated whether the set power value Wd as the result of the control coincides with the thermal power Ws or not, and in the case of NO, the above processes are repeated till the power value Wd coincides with the thermal power Ws. As described above, according to this embodiment, in the reactor burn-up compensation, since the thermal power Ws of the steam generator 141 can be controlled to a value corresponding to the set power value only by operating the feed water flow rate Gw, even if the failure of the power plant control unit 148 be caused, the possibility of erroneous draw-out of the control rod from the core 155 can be substantially prevented, thus performing the operation of the power plant stably. Next, the generator load follow-up control will be described by way of the flowchart of FIG. 25. When the load of the generator 135 is lowered, the main steam governor 158 is closed. The main steam pressure is thereby increased and the turbine bypass valve 159 is opened to bypass the excess steam to the condenser 160. In order to lower the power of the fast reactor 154 in conformity with the load of the generator 135, the set power value Wd is gradually lowered by the power setter 153. In Step 211, the thermal power Ws is calculated by the thermal power calculation section 148a. In the next Step 212, a deviation (Wd-Ws) is caused between the lowered set power value Wd and the calculated thermal power Ws. In Step 213, the deviation (Wd-Ws) is obtained in the thermal power control section 148b and the feed water flow rate signal Gd is set through a linear calculation. In Step 214, the feed water flow rate Gw and the feed water flow rate signal Gd are inputted and stored by the flow rate control section 148c, and in Step 215, the deviation (Gd-Gw) between the feed water flow rate Gw and the feed water flow rate signal Gd is obtained and the flow rate regulating valve opening degree signal Zd is set to thereby control the feed water flow rate regulating valve 147. In Step 216, it is discriminated whether the set power value Wd as the result of the control coincides with the thermal power Ws or not, and in the case of NO, the above processes are repeated till the power value Wd coincides with the thermal power Ws. FIG. 26 shows a reactor provided with a reactor vessel in which a plurality of core vessels each accommodating a module core are accommodated. A conventional liquid metal cooling type reactor accommodates single core in its reactor vessel, and according to large power requirement of the reactor, the reactor is enlarged in size with single core, resulting in complicated control of the core and, in case of an accident of a portion of the core, the accident affects entirely the large core operation, which in turn results in the shut-down of the reactor operation. Furthermore, in the conventional reactor, since it is aimed to make large the core with maintaining single core, the core structure including, for example, a core support structure, is made large in size, and accordingly, hard labour, much time and troublesome working are required for workers or operators of the reactor at the time of removing or assembling the core structure for the purpose of periodical inspection, maintenance and the like. In the removing working and the assembling working of the core support structure, it is necessary to carefully handle the core structure itself, retire the entire core structure externally of the reactor vessel and additionally locate a device for storing or discharging liquid metal as the primary coolant. Furthermore, in the conventional reactor, the reactor is enlarged in size with maintaining single core, so that the power shut-down of the core also results in the stopping of the operation of the power plant itself, thus giving an economical damage. Still furthermore, since only the single core is disposed in the reactor, it is necessary to carry out the core designing or nuclear critical experiment every time in accordance with the power of the nuclear power plant, thus being inconvenient in evidencing the core characteristics. The present invention was conceived in consideration of the above facts, and according to the present invention, the power of the nuclear power plant can be increased in combined arrangement of a plurality of core vessels and the easiness of the core control can be ensured even if the power of the power plant is increased. FIG. 26 represents an embodiment of the present invention applied to a liquid metal cooling type tank type reactor. In this embodiment, a reactor chamber 221 is formed in a reactor building 220. The reactor chamber 221 is installed on a base mat 224 and enclosed by a biological shilding wall 222 made of concrete and a biological shilding ceiling wall 223 also made of concrete, and a reactor vessel 225 as a tank type primary coolant vessel is accommodated in the reactor chamber 220. Liquid metal such as liquid metal sodium fills in the reactor vessel 225 as primary coolant 226, and the interior of the reactor pressure vessel 225 is divided into an upper plenum 228 and a lower high pressure plenum 229 by means of a pressure partition wall 227. The reactor vessel 225 has a top opening which is covered by an upper cover 230 as a shielding plug, and the upper cover 230 is formed with through holes through which core vessels 231 and intermediate cooling machines 232 are perpendicularly arranged so as to be suspended into the reactor vessel through an upper mirror plate. The upper cover 230 further constitutes a portion of the biological shielding ceiling 223. A plurality of, for example, nine, as shown in FIG. 27, core vessels 231 are arranged circularly along the inner peripheral wall of the reactor vessel 225, and one or a plurality of, for example, three, intermediate cooling machines 232 are arranged inside the circularly arranged core vessels 231. In each of the core vessels 231, a core, i.e. module core, 235 composed of fuel rods and control rods is accommodated, and each of the core vessels 231 is provided with a shell having a lower portion to which a flow-in nozzle 236 is formed and an upper portion to which a flow-out port 237 is also formed. The flow-in nozzle 236 is fitted to an opening formed at an attaching protion of the pressure partition wall 227 and opened to the lower plenum 229, and the flow-out port 237 is opened to the upper plenum 228. A core shielding plug 240 is attached to an upper opening of the core vessel 231 and a control rod driving mechanism 241 is disposed above the core shielding plug 240. The insertion or charging of the control rods 242 into the core 235 can be controlled by the control rod driving mechanism 241. Each of the intermediate cooling machines 232 is provided with a cylindrical intermediate cooling vessel 244 in which an intermediate heat exchanger 245 for performing heat exchanging operation between the primary coolant and the secondary coolant and a circulation pump 246 for forcibly circulating the primary coolant are accommodated. The circulation pump 246 is composed of an electromagnetic pump which is disposed below the intermediate heat exchanger 245. A flow-out nozzle 247 is formed to the lower portion of the circulation pump 246 and the flow-out nozzle 247 is fitted with and supported by the attachment opening of the pressure partition wall 227 so as to be opened to the inside of the lower high pressure plenum 229. The intermediate cooling machine 244 forms, at its upper portion, a flow-in port 248 which is opened to the inside of the upper plenum 228. An intermediate cooling machine shielding plug 250 is fitted to the upper opening of the intermediate cooling vessel 244, and a secondary coolant flow-in and -out tube 252 connected to a steam generator 251 is disposed above the shielding plug 250. The flow-in and-out tube 252 connects the steam generator 252 and the intermediate heat exchanger 245 to thereby constitute a closed circulation loop for circulating the secondary coolant. The steam generator generates steam utilized for driving a steam turbine, not shown. When the ractor of this embodiment is operated, the primary coolant flows from the lower high pressure plenum 229 of the reactor vessel 225 into the core vessel 231 through the flow-in nozzle 236. The thus fed primary coolant 226 is heated through nuclear reaction heat during the passing through the core 235 in each of the core vessels 231 and then discharged into the upper plenum 228 through the flow-out port 237. The primary coolant of high temperature guided to the upper plenum 228 is then guided to the intermediate heat exchanger 245 through the flow-in port 248 of the intermediate cooling machine 232 and passes tubes of the intermediate heat exchanger 245. At this time, the heat exchanging operation is carried out between the primary coolant and the secondary coolant, thus the primary coolant being cooled. The primary coolant transferring the heat to the secondary coolant and reduced in its temperature is reduced in its pressure by the electromagnetic pump and then returns into the high pressure plenum, i.e. lower plenum, 229 through the flow-out nozzle 247. On the other hand, the secondary coolant heated by the intermediate heat exchanger 245 in the intermediate cooling machine 232 fed to the steam generator 251 through the flow-in and -out tube 252 and heats therein the water, thus generating the steam for driving the steam turbine. The secondary coolant cooled by heating the water in the steam generator returns to the intermediate heat exchanger 245 of the intermediate cooling machine 232 through the flow-in and out tube 252. In the reactor of this embodiment, in a case where a plurality of core vessels 231 as the primary coolant vessels are accommodated in the reactor vessel 225 and it is assumed that the thermal power per one module core 235 disposed in the core vessel 231 is 100000 KW as a small core, the total thermal power of the reactor having the reactor vessel in which nine core vessels 231 are accommodated is 9.times.100000=900000 KW, which is large power as a single reactor power, will be obtained. Accordingly, different from a conventional reactor of liquid metal cooling type having a reactor in which single large core is accommodated, the reactor of the present embodiment is composed of a plurality of combined small cores, each of which is relatively easily handled or managed, and a large power as one reactor can be obtained with maintaining the characteristic feature of a small sized core 235, which can be easily operated and controlled. For example, in the case of a small sized core having the thermal power of 100000 KW per one core 235, the outer diameter of the core vessel 231 can be made within 1.5 m. For the reason described above, even in a case where a plurality of core vessels 231 are disposed in the reactor vessel 225 to thereby increase the reactor power as single reactor, the enlargement in size of the core structure such as core support structure can be avoided and a small sized core structure can be provided, and accordingly, the removal or exchanging thereof can be easily made. Furthermore, according to the arrangement of the core vessels 231 along the inner peripheral wall of the reactor vessel 225, the accessibility to the core vessels 231 can be improved. Particularly, at the upper surface of the biological shielding ceiling wall 223, the accessibility of the fuel exchanging device to the respective module cores 235 and the accessibility for the removal or exchanging of the respective core vessels 231 including the core support structure can be also improved, thus being advantageous. Furthermore, since the intermediate cooling machine 232 is constructed in combination of the intermediate heat exchanger 245 and the circulation pump 246, a space for arranging machineries or equipments in the inside area of the array of the core vessels 231 can be sufficiently ensured. FIGS. 28 and 29 represent a reactor of another embodiment according to the present invention. This embodiment differs from that of FIG. 26 in a point that the installed numbers and the structures of the core vessels 260 and the intermediate cooling machines 261 disposed in the reactor vessel are different, and other arrangements or structures are substantially the same as those of the embodiment of FIG. 26, and the like reference numerals are added to equipments or units corresponding to those of FIG. 26. In this embodiment of FIGS. 28 and 29, a plurality of, for example, ten core vessels 260 are arranged circumferentially along the inner peripheral wall surface of the reactor vessel 225 and, in each of the core vessels 260, a core 262 is disposed to an upper portion thereof and an electromagnetic pump as circulation pump 263. The core vessel 260 is provided with a flow-in nozzle 236 disposed below the circulation pump 263 and the flow-in nozzle 236 is fitted to and supported by an opening formed to an attaching portion of the pressure partition wall 227 to thereby establish the communication of the core vessel 260 with the lower plenum 229 through the flow-in nozzle 236. The core vessel 260 is also provided with a flow-out port 237 above the core 262, and the primary coolant increased in its pressure by the circulation pump 263 and heated by the core 262 is guided to the upper plenum 228 through the flow-out port 237. In the meantime, one or plurality of intermediate cooling machines 261 are arranged inside the core vessels 260 circumferentially along the inner peripheral wall of the reactor vessel. The intermediate cooling machine 261 is constructed as an intermediate heat exchanger 266 accommodated in a intermediate cooling vessel 265, and a flow-out nozzle 247 is formed below this intermediate heat exchanger 266 and a flow-out port 248 is disposed thereabove. According to the structure of the reactor of this embodiment described above, the primary coolant of high temperature guided to the upper plenum 228 is then guided to the intermediate heat exchanger 266 through the flow-in port 248 of the intermediate cooling machine 261, and in the intermediate heat exchanger 266, the heat exchanging operation is performed between the primary coolant 226 and the secondary coolant. The primary coolant 226 cooled through the heat exchanging operation is guided into the lower plenum 229 through the flow-out nozzle of the intermediate cooling machine 261 and then returns into the core vessel 260 through the flow-in nozzle 236. Then, the secondary coolant having a temperature increased through the heat exchanging operation in the intermediate heat exchanger 266 is fed to the steam generator 251 through the flow-in and -out tube 252 and heats the water therein to thereby generate the steam which in turn drives the steam turbine, not shown. The secondary coolant reduced in its temperature after the heating of the water again returns to the intermediate heat exchanger 266 through the flow-in and -out tube 252, thus constituting a closed circulation loop of the secondary coolant. According to the reactor of this embodiment, in addition to the functions and effects of the embodiment of FIGS. 26 and 27, there can attain further function such that, in a case where an abnomality is caused to the circulation pump 263 provided for each of the core vessels 260, the operation of only the core 260 related to that circulation pump 263 is stopped by the control rod driving mechanism 241 and other cores can be operated continuously as they are. FIGS. 30A and 30B are plan views of an upper portion of reactors according to further embodiments of the present invention and show examples of reactor power modifications. In the modification of FIG. 30A, nine core vessels 231 having the same design are accommodated in the reactor vessel 225 and in the modification of FIG. 30B, six core vessels 231 are accommodated. In these embodiments, the respective core vessels 231 are constructed with the same design, and for example, assuming that the thermal power of one core reactor is 100000 KW, the single reactor power of 900000 KW can be obtained by the reactor of FIG. 30A and the single reactor power of 600000 KW can be obtained by the reactor of FIG. 30B. Accordingly, in the assumption of the same core design, various reactor power can be selected by the combination of the numbers of the evidenced module cores. Further, it is to be noted that in the above explanation, the embodiments of evidenced small sized module cores having the same design were explained, it may be possible to preliminarily prepare evidenced small sized cores having various thermal powers. FIG. 31 shows a reactor of reflector control type capable of controlling reactivity of a core by vertically moving a neutron reflector and capable of operating the reactor without changing fuel for a long time, maintaining void reactivity negative during the reactor operation period and obtaining a large power. Referring to FIG. 31, a primary coolant vessel 321 is installed in a reactor chamber 325 surrounded by a biological shielding wall 322, a buidling base mat 323 and a biological shielding ceiling 324. Within the primary coolant vessel 321, a high pressure plenum 327 formed by a pressure partition wall structure 326 is disposed at the bottom portion thereof and a plurality of core vessels 328 are perpendicularly arranged circumferentially along the side wall. Each of these core vessels 328 is provided at its lower portion with a core vessel flow-in nozzle 329 and a core vessel flow-out port 330 is also formed above a shell portion thereof. The core vessel 328 has an upper opening to which a core shielding plug 331 is mounted. A core 332 composed of fuel rods and a reflector 333 is accommodated inside the core vessel 328 and a reflector driving mechanism 334 is disposed above the core shielding plug 331. One or plurality of intermediate cooling machines 335 are perpendicularly arranged in an inside area of the circularlly arranged core vessels 328. As shown in FIG. 31, each of these intermediate cooling machines 335 is provided with flow-out nozzle 336 at its lower portion and a flow-in port 337 at an upper portion of a shell thereof, and a shielding plug 338 is also mounted to an upper opening portion of the intermediate cooling machine 335. The interior of the intermediate cooling machine 335 is composed of an intermediate heat exchanger 340 disposed to an upper portion therein for carrying out the heat exchanging operation between the primary coolant and the secondary coolant and a primary electromagnetic pump 341 disposed to a lower portion therein for circulating the primary coolant 339. A secondary coolant flow-in and -out tube 342 for heating a steam generator, not shown, is arranged above the intermediate cooling machine shielding plug 338. The biological shielding ceiling 324 is formed with through holes for inserting the core vessels 328 and the intermediate cooling machines 335 into the primary coolant vessel 321 through the upper mirror plate of the primary coolant vessel 321 so that the core vessels 328 and the intermediate cooling machines 335 can be inserted or removed through these through holes. The high pressure plenum 327 composed of the pressure partition wall structure 326 is provided with an opening into which the flow-out nozzle 336 of the intermediate cooling machine is fitted, thereby guiding the primary coolant 339 to an annular core distribution plenum 327a from the high pressure plenum 327. The annular core distribution plenum 327a is formed with an opening into which the core vessel flow-in nozzle 329 is fitted. The primary coolant 339 is fed to the flow-in nozzle 329 from the core distribution plenum 327a and discharged through the flow-out port 330 of the core vessel after being heated during the passing through the core 332. Thereafter, the primary coolant 339 is fed into the intermediate cooling machine through its flow-in port 337 and passes the tube bundles in the intermediate heat exchanger 340 and, during this passing, the heat exchanging operation is carried out between the primary coolant and the secondary coolant to transfer the heat to the secondary coolant. After the pressure increasing by the primary electromagnetic pump 341, the primary coolant 339 returns to the high pressure plenum 327 through the flow-out nozzle 336 of the intermediate cooling machine 335. Neutron shields 343 are disposed to the outer peripheral portion of the cores 332 of the respective core vessels 328 to prevent them from nuclearly interferring with each other. As described above, for example, assuming the location of single small sized core 332 having a thermal power of 100000 KW, for the reactor of this embodiment provided with six cores 332, a large thermal power of 6.times.100000 KW=600000 KW can be obtained. Furthermore, each core 332 is small sized, so that a reactor capable of keeping negative the void reactivity without exchanging the fuel for a long time. FIGS. 33 and 34 represent anther embodiment of a reactor in relation to the embodiment of FIGS. 31 and 32. Referring to FIGS. 33 and 34, a plurality of, for example, seven, core vessels 328 is perpendicularly arranged at the central portion in the primary coolant vessel 321, and for example, three intermediate cooling machines 351 and three primary mechanical pumps 352 are also perpendicularly arranged in an annular area outside the arrangement of the core vessels 328 with circemferentially equal space with each other. Each of the intermediate cooling machines 351 has a structure similar to that of the former embodiment but excluding the primary electromagnetic pump 341. The primary mechanical pump 352 is directly connected to the pressure partition wall structure 326 so as to guide the primary coolant 339 to the core distribution plenum 327a after rectifying the same by a coolant introducing header 353. The core distribution plenum 327a is formed with an opening into which the flow-in nozzle 329 of the core vessel is fitted, and the core distribution plenum 327a and the low pressure plenum 354 are mutually communicated with each other through a pressure reducing coupling tube 355. The lower mirror plate of the primary coolant vessel 321 and the pressure partition wall support plate 356 constitutes a pump suction plenum 357 which is formed with an opening into which the flow-out nozzle 336 of the intermediate cooling machine. Stand pipes 358a and 358b constituting a suction port of the primary mechanical pump 352 are also connected to the pump suction plenum 357. The other structure of the reactor of this embodiment of FIGS. 33 and 34 are substantially the same as those of the former embodiment of FIGS. 31 and 32. According to the structure described above, the primary coolant 339 is fed to the flow-in nozzle 329 of the core vessel from the high pressure plenum 327, heated during the passing through the core 332 and then discharged through the flow-out port 330 of the core vessel. Thereafter, the primary coolant 339 is sucked through the flow-in port 337 of the intermediate cooling machine and transfers its heat to the secondary coolant during the passing through the tube bundles in the intermediate heat exchanger 340 through the heat exchanging operation therebetween. The primary coolant after cooled through the heat exchanging operation is discharged to the pump suction plenum through the flow-out nozzle 336 of the intermediate cooling machine and then returns to the core distribution plenum 327a by the actuation of the primary mechanical pump 352. According to this embodiment, too, a large power can be obtained as in the former embodiment and the void reactivity can be maintained negative without exchanging the fuel for a long time. In this embodiment, even in an alternation of the primary mechanical pump 352 to the electromagnetic pump, substantially the same effects will be attained. Although in the former embodiments, six core vessels 328 are arranged in the primary coolant vessel 321 along the inner circumferential periphery thereof or seven core vessels 328 are arranged therein at the central portion thereof, further modifications or changes may be made for attaining substantially the same functions and effects. Such modifications are explained hereunder with reference to the illustration of plan views of FIGS. 35 to 42. First, in a reactor of FIG. 35, one intermediate cooling machine 351 is arranged at the central portion of the primary coolant vessel 321, three primary mechanical pumps 352 are disposed at an outer peripheral side thereof, and respectively two, totally six, core vessels 328 are arranged between adjacent two primary mechanical pumps 352. In a reactor of FIG. 36, one intermediate cooling machine 351 is arranged at the central portion of the primary coolant vessel 321, six core vessels are disposed at an outer peripheral side thereof, and further three core vessels 328 are arranged outside the former six core vessels 328. Six intermediate cooling machines 351 and the primary mechanical pumps 352 are further disposed at the outer peripheral portion thereof. In a reactor of FIG. 37, thirteen core vessels 328 are disposed at the central portion of the primary coolant vessel 321 and three intermediate cooling machines 351 and three primary mechanical pumps 352 are arranged to the outer peripheral portion thereof. In a reactor of FIG. 38, seven core vessels 328 are arranged at the central portion of the primary coolant vessel 321, further three core vessels 328 are disposed outside thereof, and three intermediate cooling machines 351 and three primary mechanical pumps 352 are arranged further outside thereof. In a reactor of FIG. 39, one core vessel 328 is disposed at the central portion of the primary coolant vessel 321, three primary mechanical pumps 352 are arranged outside the core vessel 328, and three intermediate cooling machines 351 are disposed at the outer peripheral portion thereof. Further six core vessels 328 are arranged outside the arrangement of the intermediate cooling machines 351. In a reactor of FIG. 40, seven core vessels 328 are arranged at the central portion of the primary coolant vessel 321 and three core vessels are further disposed to the outer periphery thereof. Three primary mechanical pumps 352 are arranged further outside the core vessels 328 and six core tubes 361 are arranged further outside the primary mechanical pumps 352. In a reactor of FIG. 41, six core vessels 328 are arranged at the central portion of the primary coolant vessel 321, three intermediate cooling machines 351 are disposed outside the core vessels 328, and three primary mechanical pumps 352 are further disposed to the outer periphery thereof. In a reactor of FIG. 42, three core vessels 328 are arranged at the central portion of the primary coolant vessel 321, further three core vessels are disposed to the outer periphery thereof, and six core tubes 361 are arranged further outside thereof. FIG. 43 shows a further embodiment of a reactor according to the present invention, in which a porous rectifying cylinder 371 for the core and a porous rectifying cylinder 372 for the intermediate heat exchanger are further disposed in addition to the embodiments described above. Namely, referring to FIG. 43, the porous rectifying cylinder 371 for the core is concentrically arranged with the primary coolant vessel 321 so as to cover all the core vessels 328 in the primary coolant 339. This porous rectifying cylinder 371 is provided with a penetrating portion for the respective core vessels 328 and a seal mechanism 373 is provided for this penetrating portion to seal the communication between the outside and the inside of the rectifying cylinder 371 for the core. The primary coolant 339 of high temperature flown out from the flow-out port 330 of the core vessel 328 is dispersed through a plurality of holes formed to the peripheral surface of the rectifying cylinder 371. On the other hand, the porous rectifying cylinder 372 for the intermediate heat exchanger is mounted to the outer peripheral portion of each of the respective intermediate cooling machines 351, and a plurality of holes are formed to the outer peripheral surface thereof at portions immersed in the primary coolant 339. The lower end of the rectifying cylinder 372 is opened to the primary coolant 339. The primary coolant 339 flown out from the porous rectifying cylinder 371 for the core is guided to the flow-in port 337 of the intermediate cooling machine 351 through the holes and lower end opening of the porous rectifying cylinder 372 for the intermediate heat exchanger, thereby suppressing the flow velocity of the primary coolant 339. The other structures or arrangements of the reactor of this embodiment is substantially the same as those of the former embodiments, and the functions and effects are also the same as those of thereof. As described above, since the flow velocity of the primary coolant 339 can be suppressed by the location of both the porous rectifying cylinders 371 and 372, the gas involving at the free liquid surface of the primary coolant can be prevented and, accordingly, the vibration of the liquid surface thereof can be reduced, thus realizing a stable coolant flow condition. The reactor of this embodiment can be applied to reactors other than those of the embodiments described above with like functions and effects. FIGS. 44 to 46 further represent another embodiment of the present invention adapted for, for example, easily performing the fuel exchanging operation per core one unit batch in comparison with the former embodiments. Namely, referring to FIGS. 44 to 46, a fuel exchanging confinement 381 is arranged to an upper portion of a reactor chamber 325 and a rotary table 382 is disposed above the reactor chamber 325 and on the floor surface of the fuel exchanging confinement 381. The rotary table 382 is formed with a fuel exchanging hole 382a and a hole 382b, having a diameter larger than that of the hole 382a, for withdrawing the reflector driving mechanism, and these holes are positioned to positions corresponding to the locations of the core vessels 382 for the purpose of easy fuel exchanging operation. The fuel exchanging per core one unit batch is performed as follows. First, the reflector driving mechanism 334 for the core objective to the fuel exchanging and the core shielding plug 331 are removed from the reactor. This removal is carried out through the reflector driving mechanism drawing-out hole 382b of the rotary table 382. In the next step, the used fuels are drawn out one by one and the new fuels are charged also one by one in a ractor cover gas boundary defined by a guide cylinder 383, a fixed door valve 384, a fuel carrying cask 385 and a cask door valve 386. The exchanged fuels are transferred to a fuel conveying cask 388 at which the used fuels are exchanged with the new fuels. The conveying-in or conveying-out working of the fuel conveying cask 388 from the reactor building is performed by transferring the fuel conveying cask 388 by a gantry crane 391 with respect to a truck trailer 390 of a truck yard 389. This guntry crane 391 can be also used for conveying the fuel conveying cask 385. In the case of conveying in or conveying out the fuel conveying cask 388, a consideration is paid not for simultaneously opening a ceiling shutter 392 and a shutter 393 of the truck yard 389 to prevent the breakage of the fuel exchanging confinement 381. As described above, according to this embodiment, the rotary table 382 is utilized, the fuel can be easily and safely exchanged per core one unit batch in the case where a plurality of core vessels 328 are arranged in single primary coolant vessel 321. The above the description was made to the example for performing the fuel exchanging operation in the reactor, and substantially the same will be applied to the other reactors having different structures.
	claims	1. A method of reticle field-wide hierarchy management, comprising:providing placement information of a hierarchical chip layout across a reticle field;generating templates and building a litho hierarchy tree for an entire reticle field in accordance with the placement information, the templates accounting for variation due to one or more of: positional environment within the reticle field, proximity environment, and structural functionality requirements;determining an exterior environment for each instance of a template candidate cell definition;generating a set of distinct environments for the exterior environments resulting from instances of the template candidate cell definition; andpartitioning instances of the template candidate cell definition to a corresponding one of the distinct environments to create one or more templates, in accordance with the respective exterior environments of the template candidate cells. 2. The method as claimed in claim 1, wherein the step of providing placement information comprises providing locations for instances of the chip layout as array references across the reticle field. 3. The method as claimed in claim 1, wherein the step of providing placement information comprises providing coordinates for instances of the chip layout across the reticle field to thereby enable arbitrary placement of the instances in the reticle field. 4. The method as claimed in claim 1, further comprising defining a reticle field-level cell encompassing at least one chip-level cell corresponding to the chip layout. 5. The method as claimed in claim 1, further comprising the step of defining primitive unit cells in the chip layout. 6. The method as claimed in claim 1, wherein the step of generating the templates in accordance with the placement information comprises generating the templates by assigning instances to distinct environments, wherein the environments are distinguished by cells in regions adjacent to each of the instances. 7. The method as claimed in claim 1, wherein the step of generating the templates in accordance with the placement information comprises generating the templates by assigning instances to different functional requirements pertaining to each of the instances. 8. The method as claimed in claim 1, wherein the step of generating the templates in accordance with the placement information comprises generating the templates by assigning instances to distinct environments, wherein the environments are distinguished by positional environment pertaining to each of the instances. 9. The method as claimed in claim 8, wherein the positional environment arises from at least one of lens aberration, optical flare, and/or pupil illumination non-uniformity. 10. The method as claimed in claim 1, wherein the, step of generating the templates in accordance with the placement information comprises:first grouping instances subject to common proximity perturbation effects; andthen further grouping the instances to address positional perturbation effects. 11. The method as claimed in claim 10, wherein the positional perturbation effects include at least one of lens aberration, optical flare, and/or pupil illumination non-uniformity. 12. The method as claimed in claim 1, further comprising distributing a computational task for an integrated circuit layout design on a reticle field wide basis among a collection of networked computation nodes, by carrying out the steps of:assigning the computation tasks for the templates to the networked computation nodes for concurrent execution; andassembling outputs from the computation nodes. 13. An integrated circuit manufactured according to the method of claim 12. 14. The method as claimed in claim 12, wherein the step of assembling outputs comprises creating a final processed circuit layout for the entire reticle field. 15. The method as claimed in claim 12, wherein the computational tasks are independent subtasks. 16. An integrated circuit manufactured according to the method of claim 1. 17. A method of reticle field-wide hierarchy management in an integrated circuit chip layout design, the method comprising the steps of:receiving a chip layout in hierarchical form;receiving placement information for the chip layout across a reticle field; and generating templates and building a litho hierarchy tree for an entire reticle field in accordance with the placement information; wherein the step of generating the templates and building the litho hierarchy tree comprises:for each instance of a template candidate cell definition, determining an exterior environment;for the exterior environments resulting from instances of the template candidate cell definition, generating a set of distinct environments; andpartitioning instances of the template candidate cell definition to a corresponding one of the distinct environments to create one or more templates, in accordance with the respective exterior enviromnents of the template candidate cells. 18. The method as claimed in claim 17, wherein the step of generating templates and building the litho hierarchy tree further comprises preprocessing steps of:identifying primary geometries of template candidate cells;generating primitive unit cells (PUC's) from the primary geometries of the template candidate cells; andassigning a unique identifier to each of the primitive unit cells. 19. The method as claimed in claim 17, wherein the step of determining the exterior environment for an instance comprises determining the said instance's proximity environment. 20. The method as claimed in claim 17, wherein the step of determining the exterior environment for an instance comprises determining the said instance's functional environment. 21. The method as claimed in claim 17, wherein the step of determining the exterior environment for an instance comprises determining the said instance's positional environment. 22. An integrated circuit manufactured according to the method of claim 17. 23. A method of partitioning a plurality of instances of a template candidate cell in a hierarchical chip layout design, the method comprising:identifying adjacent regions for each of the instances of the template candidate cell;generating an exterior environment for each of the instances of the template candidate cell, said exterior environment comprising one or more primitive unit cells (PUC's) overlapping or in contact with the adjacent regions of each of the instances;generating a set of unique environments for the exterior environments resulting from instances of template candidate cell definition; andassigning the instances of the template candidate cell to corresponding ones of the unique environments based on the PUC's. 24. The method as claimed in claim 23, wherein the adjacent regions correspond to regions within a range of influence for the instances. 25. The method as claimed in claim 24, wherein the range of influence is about 0.61.1 m. 26. The method as claimed in claim 23, wherein PUC identifiers are used to represent the primitive unit cells. 27. The method as claimed in claim 23, wherein the step of determining the set of unique environments comprises comparing identities and transforms for the PUC's. 28. The method as claimed in claim 23, further comprising defining templates for the instances based on the unique environments. 29. The method as claimed in claim 28, further comprising applying corrections for geometrical features within the templates. 30. The method as claimed in claim 29, wherein the corrections for geometrical features within the templates are computed by distributing respective templates for computation to respective ones of a collection of networked computation nodes. 31. The method as claimed in claim 30, wherein the computation nodes perform the intended computations for the templates concurrently. 32. The method as claimed in claim 30, wherein the computation nodes perform the intended computations for the templates on a reticle-wide basis. 33. The method as claimed in claim 28, further comprising determining optical proximity corrections for the templates. 34. The method as claimed in claim 28, further comprising determining corrections for the templates to address positional perturbations. 35. The method as claimed in claim 28, further comprising determining corrections for the templates to address functional requirements. 36. An integrated circuit manufactured according to the method of claim 23. 37. A computer program product comprising a computer useable medium having a computer readable program code functions embedded in the medium for causing a computer to manage for reticle field-wide hierarchy management in an integrated circuit chip layout design, the product comprising a computer-readable medium in which program instructions are stored, which instructions, when read by a computer, cause the computer to:receive the chip layout in hierarchical form;receive the placement information for the chip layout across the reticle field; and generating templates and building a litho hierarchy tree for an entire reticle filed in accordance with placement information, wherein said generating comprises:for each instance of a template candidate cell definition of the chip layout, determine an exterior environment;for the exterior environments resulting from instances of the template candidate cell definition, generate a set of unique distinct environments;partition the collection of instances of the template candidate cell definition to create one or more templates in accordance with their respective exterior environments; andgenerate the templates. 38. The product as claimed in claim 37, further comprising a third computer readable program code that causes the computer to determine if particular cell definitions are suitable candidates as templates. 39. The product as claimed in claim 37, further comprising fourth third computer readable program code that causes the computer to determine a proximity environment for each instance. 40. The product as claimed in claim 37, further comprising a fourth computer readable program code that causes the computer to determine a functional environment for each instance. 41. The product as claimed in claim 37 further comprising a fourth computer readable program code that causes the computer to determine a positional environment for each instance. 42. An integrated circuit manufactured with the computer program product of claim 37. 43. A computer program product for partitioning a plurality of instances of a template candidate cell in a hierarchical chip layout design the computer program product having a computer readable program instructions embedded in the medium for causing a computer to:identify adjacent regions for each of the instances of the template candidate cell;generate an exterior environment for each of the instances of the template candidate cell, said exterior environment comprising one or more primitive unit cells (PUC's) overlapping or in contact with the adjacent regions of each of the instances;generating a set of unique environments for the exterior environments resulting from instances of the template candidate cell definition; andassign the instances of the template candidate cell to corresponding ones of the unique environments based on the primitive unit cells. 44. The product as claimed in claim 43, wherein the adjacent regions correspond to regions within a range of influence for the instances. 45. The product as claimed in claim 43, wherein the instructions further cause the computer to compare identities and transforms for the PUC's. 46. The product as claimed in claim 43, wherein the instructions further cause the computer to define templates for the instances from unique environments. 47. The product as claimed in claim 46, wherein the instructions further cause the computer to distribute the templates among a collection of networked computation nodes. 48. The product as claimed in claim 47, wherein nodes are separate workstations. 49. The product as claimed in claim 47, wherein the instructions further cause the computer to perform intended computations for the templates. 50. The product as claimed in claim 47, wherein the instructions further cause the computer to perform the intended computations for the templates concurrently. 51. The product as claimed in claim 46, wherein the instructions further cause the computer to perform intended computations for the templates. 52. The product as claimed in claim 46, wherein the instructions further cause the computer to perform optical proximity corrections for the templates. 53. The product as claimed in claim 46, wherein the instructions further cause the computer to perform corrections for the templates to address positional perturbations. 54. The product as claimed in claim 46, wherein the instructions further cause the computer to perform corrections for the templates to address functional requirements. 55. An integrated circuit manufactured with the computer program product of claim 43. 56. A computer program product for distributing computational tasks for an integrated circuit layout design on a reticle field wide basis among a collection of networked computation nodes, the computer program product having a computer readable program instructions embedded in the medium for causing a computer to:generate a plurality of templates and building a litho hierarchy tree for an entire reticle field in accordance with a placement information of the integrated circuit layout across the reticle field;assign the computation tasks for the templates to the networked computation nodes for concurrent execution; andassemble outputs from the computation nodes, wherein generating the templates and building the litho hierarchy tree comprises:for each instance of a template candidate cell definition, determining an exterior environment;for the exterior environments resulting from instances of the template candidate cell definition, generating a set of distinct environments; andpartitioning instances of the template candidate cell definition to a corresponding one of the distinct enviromnents to create one or more templates, in accordance with the respective exterior environments of the template candidate cells. 57. The product as claimed in claim 56, wherein the computational tasks are independent subtasks. 58. The product as claimed in claim 56, wherein the instructions further cause the computer to create a final processed circuit layout for the entire reticle field.
	summary
	summary
	claims	1. A nuclear reactor power regulator that adjusts a power output of a reactor, comprising:an input to receive a reactor output target value and a reactor output change rate that are input by a central load dispatching center or an operator;a reactor output calculating device configured to perform computations based on a thermal equilibrium from power signals of plant parameters obtained from the reactor and to calculate a reactor output signal, the reactor output signal being a signal calculated intermittently;a correcting device configured to receive the reactor output signal from the reactor output calculating device and a reactor output equivalent signal which is continuously obtained and correlated with the reactor output signal at a calculation interval in the reactor output calculating device, and that corrects the reactor output equivalent signal so that a reactor output level of the reactor output equivalent signal coincides with a reactor output level of the reactor output signal calculated by the reactor output calculating device based on the reactor output signal and thereby obtains a continuous corrected reactor output equivalent signal;a reactor output controlling device configured to receive the continuous corrected reactor output equivalent signal and that calculates at least one reactor output control signal for controlling the output of the reactor, using the continuous corrected reactor output equivalent signal, the reactor output target value, and the reactor output change rate; anda reactor output controller configured to be operated based on the at least one reactor output control signal to control reactor power. 2. The reactor power regulator according to claim 1, wherein the correcting device is configured to calculate the continuous corrected reactor output equivalent signal, by multiplying the reactor output equivalent signal by gain that is corrected for each calculation interval in the reactor output calculating device. 3. The reactor power regulator according to claim 1, wherein the correcting device is configured to calculate the continuous corrected reactor output equivalent signal, by multiplying a difference between the reactor output equivalent signal and the reactor output signal calculated by the reactor output calculating device, by gain that is set in advance so that the reactor output level of the reactor output equivalent signal coincides with the reactor output level of the reactor output signal, by adding the obtained product to the reactor output signal, and by thus updating the reactor output signal at the calculation interval in the reactor output calculating device. 4. The reactor power regulator according to claim 1, wherein the correcting device calculates the continuous corrected reactor output equivalent signal, by multiplying a function that is set in advance so that the reactor output level of the reactor output equivalent signal coincides with the reactor output level of the reactor output signal calculated by the reactor output calculating device, by gain that is corrected for each calculation interval in the reactor output calculating device so that reactor output level of the reactor output equivalent signal coincides with the reactor output level of the reactor output signal during a plant operation. 5. The reactor power regulator according to claim 1, wherein the correcting device calculates the continuous corrected reactor output equivalent signal, by adding bias that is corrected for each calculation interval in the reactor output calculating device so that the reactor output level of the reactor output equivalent signal coincides with a reactor output signal during a plant operation, to a function that is set in advance so that reactor output level of the reactor output equivalent signal coincides with the reactor output level of the reactor output signal calculated by the reactor output calculating device. 6. The reactor power regulator according to claim 1, further comprising a reactor output control signal switching device that switches the at least one reactor output control signal used to control the reactor output signal between a first reactor output control signal calculated using the continuous corrected reactor output equivalent signal, the reactor output target value, and the reactor output change rate, and a second reactor output control signal calculated using a power generator output target value, a power generator output change rate, and a power generator output,wherein the at least one reactor output control signal includes the first and second reactor output control signals. 7. The reactor power regulator according to claim 6, further comprising a signal switching controller that requests, in accordance with the reactor output signal, a device to select any of the first reactor output control signal and the second reactor output control signal as the at least one reactor output control signal used to control the reactor. 8. The reactor power regulator according to claim 7, wherein the signal switching controller requests the reactor output control signal switching device to select the second reactor output control signal as the at least one reactor output control signal used to control the reactor in a case where the reactor output signal is less than a given value. 9. The reactor power regulator according to claim 7, wherein the signal switching controller requests the reactor output control signal switching device to select the first reactor output control signal as the at least one reactor output control signal used to control the reactor in a case where the reactor output signal is equal to or more than a given value. 10. The reactor power regulator according to claim 1, further comprising a change rate suppressing device that has a function of suppressing the reactor output change rate in a case of performing control using the reactor output equivalent signal corrected by the correcting device. 11. The reactor power regulator according to claim 10, wherein the change rate suppressing device has a function of switching an on/off state of the function of suppressing the reactor output change rate between an on state and an off state. 12. The reactor power regulator according to claim 10, wherein the change rate suppressing device is configured to generate a reactor output change rate suppression signal based on the continuous corrected reactor output equivalent signal, and output the generated reactor output change rate suppression signal to the reactor output controller. 13. The reactor power regulator according to claim 11, wherein the change rate suppressing device further has a function of automatically switching off the function of suppressing the reactor output change rate in any one of a case where the reactor output signal is less than a first given value and a case where a deviation between values before and after the correction of the continuous corrected reactor output equivalent signal is less than a second given value. 14. The reactor power regulator according to claim 11, wherein the change rate suppressing device further has a function of automatically switching on the function of suppressing the reactor output change rate in any one of a case where the reactor output signal is equal to or more than a first given value and a case where a deviation between values before and after the correction of the continuous corrected reactor output equivalent signal is equal to or more than a second given value. 15. The reactor power regulator according to claim 1, further comprising at least one of: a reactor output equivalent signal switching device that switchingly outputs one reactor output equivalent signal from among a plurality of the received reactor output equivalent signals as the reactor output equivalent signal; and a corrected reactor output equivalent signal switching device that switchingly outputs one continuous corrected reactor output equivalent signal from among a plurality of the corrected reactor output equivalent signals as the continuous corrected reactor output equivalent signal that are calculated by the correcting device according to respective different correction methods and are received from the correcting device. 16. The reactor power regulator according to claim 15, further comprising:a first signal switching controller that, if the reactor power regulator comprises the reactor output equivalent signal switching device, controls the reactor output equivalent signal switching device to switchingly output a reactor output equivalent signal that makes a deviation smaller, from among the plurality of received reactor output equivalent signals; anda second signal switching controller that, if the reactor power regulator comprises the corrected reactor output equivalent signal switching device, controls the corrected reactor output equivalent signal switching device to switchingly output a continuous corrected reactor output equivalent signal that makes the deviation smaller, from among the plurality of received continuous corrected reactor output equivalent signals,wherein the first and second signal switching controllers are automatically actuated in a case where the reactor output signal is equal to or more than a first given value or is less than the first given value or where a deviation between values before and after the correction of the continuous corrected reactor output equivalent signal is equal to or more than a second given value. 17. The reactor power regulator according to claim 1, further comprising:an automation on/off switching device that switches an on/off state of an automatic mode in which reactor power regulation is automatically performed; andan automation cancellation signal generating device that generates an automation cancellation signal for switching to a manual mode in which the on/off state of the automatic mode is switched from on to off and the reactor power regulation is manually performed, in a case where the reactor output signal calculated by the reactor output calculating device or the continuous corrected reactor output equivalent signal exceeds a rated reactor power by a given value or more or where the reactor output controller breaks down,wherein the automation on/off switching device automatically switches the on/off state of the automatic mode in accordance with whether or not the automation cancellation signal is received from the automation cancellation signal generating device.
	abstract	A nanotube based device for guiding a beam of x-rays, photons, or neutrons, includes a beam source and at least one nanotube. Each nanotube has an optical entrance positioned in a manner that a projection of the direction of the central axis at the optical entrance intersects with the beam source. Each nanotube may have an interior diameter that varies along the length of the nanotube. to point the entrances of a bundle of nanotubes toward a point-shaped beam source, the bundle can be grown as an array of multilayer nanotubes from a spherical growth plate. The clear aperture of the bundle is enhanced by providing a smaller number of wall layers of each nanotube near the growth plate than at a distance from the growth plate.
	abstract	A process for minimizing waste and maximizing utilization of uranium involves recovering uranium from an irradiated solid target after separating the medical isotope product, molybdenum-99, produced from the irradiated target. The process includes irradiating a solid target comprising uranium to produce fission products comprising molybdenum-99, and thereafter dissolving the target and conditioning the solution to prepare an aqueous nitric acid solution containing irradiated uranium. The acidic solution is then contacted with a solid sorbent whereby molybdenum-99 remains adsorbed to the sorbent for subsequent recovery. The uranium passes through the sorbent. The concentrations of acid and uranium are then adjusted to concentrations suitable for crystallization of uranyl nitrate hydrates. After inducing the crystallization, the uranyl nitrate hydrates are separated from a supernatant. The process results in the purification of uranyl nitrate hydrates from fission products and other contaminants. The uranium is therefore available for reuse, storage, or disposal.
	description	The present invention relates to packaging systems for radioactive materials, in particular radioactive solutions. In one special embodiment, the present invention relates to packaging systems for injectable diagnostics or drugs. Packaging systems for drugs and diagnostics are controlled by strict requirements under drugs legislation, both in terms of material compatibility and with regard to ability to sterilize. This applies in particular to injectable preparations and diagnostics. For example, no elements of the packaging used must be soluble in the solution to be packaged. Furthermore, the container must be such that it can be adequately sterilized before the contents are removed. Consequently, it is standard practice to package injectable drug preparations either in solid glass vials closed by fused ends or glass vials which can be closed by means of a stopper and optionally a flanged cap. In the latter case, the contents are usually removed by piercing a septum or the actual stopper with the syringe and drawing the solution into the syringe with the stopper closed. In order to prevent any form of contamination, the cover region must therefore be sterilized beforehand. This is done by spraying and/or wiping with ethanol solutions. In addition to these requirements intended to regulate the drug aspect, containers for radioactive materials, including radioactive solution, are subject to additional requirements with regard to containment of the emitted radiation. For transport purposes, therefore, radioactive materials are usually placed in a first packaging which is sealed. For containment purposes, this packaging is in turn placed in a lead container which acts as the actual shield. In the past, however, this type of packaging has proved to be impractical, specifically in the case of injectable drug preparations. Vials of the type that are closed by fusion are totally unsuitable for packaging radioactive materials due to the risk of the syringe becoming contaminated when the vial end is broken off in order to open them. If glass vials sealed by stoppers are used, they usually have to be completely removed from the lead container, which means that the doctor handling them is exposed to what is usually a considerable amount of radiation, depending on the radiation emitted. The same risk of exposure exists, at least in the region of the tips of the fingers by which the vials are held, even in the case of (β-radiation, which is usually shielded by a few centimeters of air. This is also not acceptable for those who constantly handle radio-chemicals and radioactive drugs. With the packaging systems used to date, therefore, it is not possible to provide shielding and permit removal of the contents with a visual control simultaneously. The sealed container has to be removed form the lead container so that the doctor can completely remove the entire solution from the vessel and visually check the removal process. In order to get round this problem, a container has been used for radioactive solutions in the past, in which a vial or another container such as an Eppendorf container is placed in a casing of Plexiglass. The container is closed with a screw cap so that a rubber seal placed on the glass vial is pressed onto the glass vial by the screw cap and is sealed by it as a result. However, this system does not meet the requirements of current drug legislation. For one thing, impurities are able to get into the solution from the screw thread, simply by turning it. Secondly, there is no guarantee that the rubber seal will remain on the opening of the glass vial when the cap is unscrewed, thereby removing the contact pressure. More specifically, this type of packaging does not allow the container serving as the shield and the actual seal of the radioactive solution to be opened separately. In addition, the seal can not be adequately sterilized if left in place. The same applies to sterilization of the screw thread. Finally, radioactive contamination of the ambient environment can not be ruled out if the seal falls out. The present invention is intended as a means of overcoming the problems of the prior art outlined above. The present invention relates to a packaging system for radioactive materials comprising, starting from the inside working outwards: (i) a vial with a closure for receiving the radioactive material, (ii) a first casing to be opened, which encloses the vial and is essentially made from a transparent material and has an appropriate capture cross-section for shielding at least a part of the emitted radiation, and (iii) a second casing to be opened, made from a material with a high capture cross section (Z) for essentially shielding the remaining radiation, the second casing enclosing the first casing. Other preferred embodiments are defined in the dependent claims. The packaging system proposed by the invention comprises (i) a vial, (ii) a first casing and (iii) a second casing, each of which is opened separately and independently of the others. In the packaging system proposed by the invention, the second casing (1, 2) assumes the shielding function as such. However, a part of this shielding function is assumed by the first casing (3, 4). The two casings can be opened separately and independently of one another. Once the second casing has been opened, however, its shielding function ceases. However, a part of it is still contained by the first casing. Due to the fact that the vial proposed by the invention has its own separate closure, the radioactive material is still sealed in the vial, even after the two casings have been opened. The vial closure, which might be a stopper (6) and flanged cap (5) for example, can now be sterilized in the same way as a conventional drug vial and pierced by a syringe in order to remove the solution after sterilization. Since the first casing proposed by the invention is made from a transparent material, it does not have to be removed in order to check that it has been completely emptied. An at least partial shield against the emitted radiation is therefore provided, even whilst the contents are being removed. The problems known from the prior art can therefore be resolved and overcome by using a vial with a closure and two casings, the first of which his made from a transparent material and has a large enough capture cross-section to shield at least some of the emitted radiation, and the second of which is made from a material with a high capture cross-section (Z) which essentially shields the remaining radiation. In principle, the first casing (3, 4) may be of any appropriate shape suitable for accommodating the vial with closure (5, 6, 7). Possible cross-sections and/or longitudinal sections are square, rectangular, polyhedral, oval or circular, for example, and the sections through the casing in planes extending perpendicular to one another need not be identical. For example, cylindrical, cube or cuboid shapes are possible, although cylindrical shapes are preferred. Likewise, the external shape of the first casing and the shape of the interior accommodating the vial and closure need not be identical, although this is preferred. A preferred embodiment is one in which the first casing is provided in the form of a cylinder, which is preferably closed at one or both ends by thicker glass plates. Although not strictly necessary, it is preferable if the glass plate(s) is or are made from the same material as the respective cylinder wall. The first casing is essentially made from a transparent material. This material has a capture cross-section (Z) suitable for shielding at least a part of the emitted radiation (e.g. β-radiation). This part might be a specific type of radiation. In the case of β-emitters such as Y-90, for example, the first casing may shield the originally emitted β-radiation completely, whereas the bremsstrahlung (usually γ-radiation) into which some of the β-radiation is already converted on passing through the vial wall, is not shielded by the first casing. Suitable materials for shielding β-radiation usually have a low atomic weight (for example carbon) and are known to the skilled person. Alternatively, the part to be shielded might be a desired part-quantity of the total radiation emitted. An example of this would be J-125 and the soft γ-radiation emitted by it. It can be shielded to a desired percentage in the first casing already, for example by selecting lead glass, in which case the rest of the radiation is shielded by the second casing. The skilled person will be able to calculate or conduct routine tests to determine the thickness of the first casing needed to obtain the desired shielding depending on the selected material, emitted radiation and dose, as well as the tolerable residual radiation. The material used for the first casing is preferably a transparent plastic. In an even more preferred embodiment, the thickness is sufficient to provide a complete shield against the β-radiation emitted by the radioactive material. The material thickness or wall thickness of the casing need not be identical over the entire casing, but may vary. Basically, any material that is sufficiently transparent with an appropriate capture cross-section and has the required resistance to the emitted radiation may be used. A transparent plastic is preferred, although other materials such as quartz or glass (for example lead glass) may also be used. The plastic is preferably selected from the group consisting of polyethylene, polypropylene, polycarbonate, polystyrene, polyethylene terephthalate, polyacrylate, polymethacrylate, in particular Plexiglass or lead Plexiglass, and copolymers containing them and mixtures thereof. The materials listed above are given by way of illustration only. In the embodiment most particularly preferred, the first casing (3, 4) encases the vial (7), and optionally an insert (8) placed underneath the base of the vial, in a tight fit. First of all, a tight-fitting enclosure will prevent the vial from sliding around in the container, which might result in damage. Furthermore, this enables the best possible use to be made of the material. An insert may be provided underneath the vial. One reason for providing this is that it can absorb any solution which might escape from the vial. It may also be provided as a means of cushioning cavities in the interior of the first casing, thereby enabling vials of different sizes to be accommodated in a standard casing, i.e. vials of different heights. As with the first casing, the second casing (1, 2) enclosing the first casing may basically be of any appropriate shape. Suitable cross-sections are square, rectangular, polyhedral, oval or round and round cross-sections are preferred. Other cross-sections would also be possible, however. Also, longitudinal sections through the casing need not necessarily be identical in planes perpendicular to the cross-sectional plane. Accordingly, cube, cuboid, polygonal or cylindrical shapes are possible and the preferred shape is cylindrical. The external shape of the second casing and the shape of the interior needed to accommodate the first casing and the vial contained in it need not be identical. The second casing is preferably also a cylinder, which is closed at both ends, preferably by cover plates. The cover plate(s) of the second cylinder is or are preferably made from the same material as the cylinder wall. However, this is not compulsory. The second casing is made from a material with a high capture cross-section (Z) for essentially shielding the remaining radiation and encases the first casing. Most preferably, the second casing encloses the first casing in a tight fit. This means that the interior of the second casing matches the shape of the first casing. If using a cylindrical design for both the first and the second casing, the internal diameter of the second casing is bigger than the external diameter of the first casing by no more than is needed to enable the first casing to slide easily in and out of the second cylinder and to enable the cap to be easily removed from the second cylinder, see below. The height of the interior of the second casing therefore corresponds to the height of the first casing. The second casing is preferably made from a metal or a metal alloy with a high Z. By a high Z is meant a high capture cross-section for the type of radiation in question. The thickness of the second casing is selected so that it is essentially sufficient to shield the remaining radiation completely. The material thickness or wall thickness of the casing need not be identical over the entire casing, but may vary. The skilled person will be in a position to select the most appropriate thickness for both casings, which may be calculated or determined by simple routine experiments. Most preferred is a metal or metal alloy from the group consisting of Al, Ag, Au, Pb, Cd, Ce, Cr, Co, Cu, Fe, Hg, Hf, Bi, In, Mg, Mn, Mo, Nb, Ni, Pd, Pt, Pr, Re, Rh, Sn, Si, Ta, Ti, Tb, Th, V, W, Y, Yb, Zn, Zr, Al/Mg, Al/Cu, Al/Cu/Mg, Al/Mg/Si, Al/Cr, Tinal alloy BB, copper alloys such as brass and bronzes, iron alloys such as Fe/Cr, Fc/Ni, Fe/Cr/Ni, Fe/Cr/Al, nickel alloys Ni/Ti, Ni/Cr, and Nitinol, platinum alloys, titanium alloys such as Ti/Al, Ti/Al/V and Ti/Mo, Woods alloys, Inconel, tungsten alloys such as Densimed and mercury alloys such as amalgams. Most especially preferred are lead or the tungsten alloy, Densimed. The first casing (3, 4) may be opened by removing a cover (3) so that a top part of the vial (7) is exposed when the casing is opened. Preferably the proportion of vial exposed is such that, although sterilization or some other manipulation such as removing the vial using tweezers or a gripper arm is possible, the vial body remains largely covered in order to guarantee continued shielding. If a commercially available primary packaging system for injection solutions is used as the vial (a glass vial of hydrolytic class I as specified in the drugs compendium), the top edge, including stopper (6) and flanged cap (5) and the groove (9) underneath it, is exposed to permit manipulation of the vial. In one particularly preferred embodiment, the first casing is provided in the form of a cylinder closed by at least a top cover plate. The cover (3) which is removed to open the first casing (3, 4) then comprises the top cover plate and a part of the cylindrical wall. The distance of the opening from the top cover plate is shorter than the distance of this opening from the bottom cover plate when the cap is removed. The distance of the opening from the top cover plate is preferably selected so that the opening is disposed directly underneath the groove (9), by reference to the vial contained in the casing, to permit manipulation. Conversely, when the cover has been removed, the entire vial body preferably remains essentially covered by the first casing. This will guarantee continued shielding. The second casing (1, 2) may also be opened by removing a cover (1). The second casing is preferably opened in such a way that once it has been opened, essentially the entire vial is visible through the transparent first casing. If the second casing is provided in the form of a cylinder closed by cover plates, the cover (1) preferably comprises the top cover plate and a (predominant) part of the cylindrical wall. By contrast with the first casing, the distance of the opening from the cover plate which results when the cover is removed is bigger than the distance of this opening from the bottom cover plate. Consequently, when the cover of the second casing is removed, a predominant or major part of the first casing, and through it the vial, is visible. In one very particularly preferred embodiment, once the second casing (1, 2) has been opened by removing the cover (1), only the bottom cover plate and optionally a smaller part of the second casing remains behind on the packaging system. This design differs significantly from conventional packaging systems in which the cover removed is usually only small. To facilitate the opening processes, the first and/or the second casing may have mating shoulders (10) or a thread. For technical reasons pertaining to the material used, it is preferable for the second casing to have a mating shoulder, especially if it is made from lead. It is also preferable to provide a mating shoulder for the first casing in order to keep the possibility of contamination as low as possible. Other types of opening designs are possible and should not be ruled out. If necessary, both casings may be sealed by means of an adhesive tape at their openings, for example. The first and the second casing may be fixedly joined to one another, at least in the region of the bottom cover plate. Adhesive, welding, etc., may be used for this purpose. However, the join must not be such that it prevents the first and second casing from being opened independently. Other designs are possible in which the second cover has a bottom cover plate and the cylindrical wall of the first casing is secured to the internal face of the bottom cover plate of the second casing. In this case, because the first casing does not have a bottom cover plate, shielding in the lower region of the container is therefore provided by the second casing only. Alternatively, the first casing may have a bottom cover plate, also made from metal, in order to provide a more intensive shield in this region. In one very particularly preferred embodiment, the first casing may be provided in the form of a cylinder closed by at least a top cover plate and the cover plate has a cut-out or orifice above the stopper of the vial, which is centrally disposed in most cases. This being the case, the radioactive material, in particular a solution, may be removed by introducing a cannula into the orifice in the first casing and piercing the stopper. With this embodiment, the doctor or person handling the system is guaranteed maximum shielding by means of the first casing, whilst simultaneously allowing removal of the contents to be visually observed. Preferably, the orifice in the cover plate of the first case is dimensioned so that the syringe body can be seated on it in a tight fit. If desirable, the vial closure of this embodiment can be sterilized before the contents are removed. To this end, the cover of the first casing may be briefly lifted, sprayed with an ethanol solution and wiped and the cover of the first casing put back in place. Only then are the contents removed. The vial used for the purposes of the invention can be closed separately. This separate closure enables the first and second casing to be opened without rendering the radioactive material contained in the vial directly accessible. On the contrary, once both casings have been opened, the contents of the vial can be drawn off without any risk of the radioactive material escaping and thus contaminating the ambient environment. In principle, the vial may be made from any appropriate material. It is preferably a transparent material. For example, all the materials specified above for the first casing are suitable in principle. More preferably, the vial is made from glass or quartz. The choice is made depending on the material to be packaged and the radiation to be shielded. The vial may be a vial with a pointed base or a vial with a flat base and the choice will depend on the material to be packaged and its volume. The dimensions of the vial are usually adapted to the volume to be packaged, which is between 1 and 25 ml, preferably 1 and 5 ml, depending on the intended purpose of the packaging system. However, smaller or larger capacities are not ruled out. The vial with closure is most preferably a so-called primary packaging system for drugs. Commercially available glass vials such as those of hydrolytic category I as specified in the drugs compendium may be used. Their use is preferred. Specifically, this is a glass vial closed by a stopper of plastic, preferably a rubber material, and optionally a flanged cap. However, other closures (stopper only), screw-on cap, etc., would also be conceivable. Basically, the radioactive materials to be packaged in the inventive packaging system may be any type of radioactive material. These materials are preferably selected from the group consisting of solutions, powder, particles, granulate, lyophilisate, liposomes, nano-particles, emulsions or suspensions of radioactive nuclides or compounds containing them, salts or alloys. They are preferably salts, oxides, fluorides, organic compounds, complexes or bio-molecules marked with nuclides such as nucleic acids, proteins, antibodies, sugars, lipids, etc. The radioactive materials are preferably solutions, emulsions or suspensions. Alternatively, a dry substance may be contained in the packaging system, such as powder, liposomes or lyophilisates, which is converted into such a solution, emulsion or suspension prior to use. The radioactive materials used for the purposes of the invention are preferably selected from β-emitters, γ-emitters and/or X-radiation emitting materials, which preferably contain a maximum particle quantity of at least 500 keV in the case of β-emission (Eβmax) and/or a photon energy in the range of from 20 to 100 keV in the case of γ-radiation and/or X-radiation. More especially preferred are the nuclides Sr-90, Y-90, Y-86, Sr-89, Tm-170, P-32, Ca-45, Cl-36, Ce-144, Tb-160, Tb-182, Tl-204, W-188, Re-188, Ir-192, Pd-103, Se-75, J-125, S-35, Lu-177, Ho-166, Re-186, Te-125m, Te-99m or mixtures thereof. Yttrium-90 is most especially preferred. The packaging system proposed by the invention may be used for transporting and/or storing radioactive materials for the short-term and medium-term. The respective activity will depend on the selected materials and wall thickness. In the case of a wall thickness of 4 mm of lead or 1 cm of Plexiglass, for example, up to 100 GBq of Y-90 (in a solution of up to 10 ml) can be packaged. The packaging system proposed by the invention will be explained on the basis of examples illustrated in FIGS. 1 to 4 of the appended drawings. FIG. 1 illustrates a preferred embodiment of the packaging system proposed by the invention in the assembled form. FIG. 2a shows a standard conventional packaging means for drugs, comprising a glass vial with a 20 mm external diameter, 12.6 mm internal diameter and a height of 47.5 mm. This glass vial has a groove approximately 1 mm below the top edge, which enables a flanged cap to be located or permits manipulation with tweezers, for example. The vial may be closed by the stopper illustrated in FIG. 2b, which is usually made from a rubber material. The stopper has a cover diameter which extends beyond the internal diameter of the glass vial and has a circular raised area on the bottom face directed towards the interior of the vial, which lies against the internal wall of the vial in the closed state, thereby providing the closure. If desired, the stopper may be additionally secured by means of a flanged cap (5) which locates in the groove (9) on the vial. As illustrated in FIGS. 1 and 3a/b, the first casing has a base (4) and a cover (3), comprising a cylinder provided with cover plates. The cylinder has a cylindrical interior, in which the glass vial can be placed in a tight fit, optionally with the aid of an underlying insert (8). The first casing (3, 4) is made from Plexiglass and has a wall thickness of approximately 9 mm. To accommodate the glass vial, the cylinder has an internal diameter of 21 mm and accordingly an external diameter of 39 mm. The total height of the cylindrical casing is approximately 83 mm and it has a mating shoulder (10) with an outwardly lying overdub of approximately 7 mm at a height of approximately 30 mm from the top cover edge. As may be seen from FIG. 1, the mating shoulder is designed so that the casing base (4) incorporates the inwardly lying web abutting with the vial, which remains in place when the casing is opened by removing the cover (3) and thereby continues to provide a shielding effect. When the cover is removed, the vial is exposed to a point just below the bottom edge of the groove (9). This enables the vial to be manipulated and optionally opened and/or removed from the packaging system with the aid of gripper arms, fingers or tweezers, for example. As may be seen from FIGS. 1 and 4a/b, the second casing in this example is also cylindrical in shape. This casing is made from lead. The cylindrical wall in this example is approximately 4 mm thick and the base and cover plates are of approximately the same thickness, although they may also be thicker. The internal diameter of the second cylindrical casing is 40 mm, as a result of which it is able to accommodate the first casing in the tightest possible fit. The height of the cylinder outside is approximately 95 mm and the height of the interior is slightly in excess of the height of the first casing. The second casing may also be opened by removing the cover (1) from the base (2). In this case, mating shoulders (10) are also provided for opening purposes, but at a distance of approximately 71 mm from the top edge of the cover plate. Consequently, when the cover is removed, the entire first casing is essentially removed and only its base (2) is left behind in the packaging system. The mating shoulders, as with the first casing, are designed so that when the mating shoulder is open, a web is left behind abutting with the first casing. However, when the cover (1) is removed, the entire vial (7) is essentially exposed so that the removal of the radioactive material from its interior can be visually observed. The base (4) of the first casing is adhered to the base (2) of the second casing. This prevents the first casing base from sliding or falling out of the second casing base. However, this fixing is not compulsory. With the selected wall thickness of 9 mm for the Plexiglass, the entire β-radiation emitted from the yttrium-90 solution can be shielded. The remaining γ-radiation is totally shielded by the second casing (1, 2) in the closed state.
	abstract	A nuclear reactor adapted for generating energy and/or decontaminating nuclear fuel using a plurality of energy beam generating accelerator devices configured for inducing a photo-fission reaction in the nuclear fuel.
	abstract	A cementitious container that has a low-frequency radio tag containing the container's pedigree and history. The container is used for storage of hazardous waste are disclosed having an inner layer of substantially unhydrated cement in contact with the hazardous waste and an outer layer of hydrated cement. Cementitious hazardous waste containers may be prepared by compressing powdered hydraulic cement around solid hazardous waste materials as well as the encapsulated radio tag that uses low frequency communication. This makes it possible to read and write information though the wall of the container as during transportation to a storage site. Once placed at the storage site, the pedigree, (history contents, Chain of Possession, Proof of delivery, weight), may be checked and verified by reading the tag on a regular basis, (once an hour), to confirm the vessel is intact and has not been moved. Sensors may also be placed on the radio tag to monitor critical parameters like temperature, light levels, movement detectors, and radioactive levels. These may be reported back via the data-link on a regular basis and may also be used as alarms if one moves outside of a specified range.
046722114	abstract	A blackbody simulator which includes a core having a non-spherical cavity and an aperture to the cavity. A substantial portion of the cavity surface is shaped so that the value of the projected solid angle of the aperture with respect to any point of the cavity surface portion is approximately constant. Simplifications to the cavity surface are achieved by increasing the apex angle. Reductions in the size and weight to the cavity may also be achieved by reducing the ratio of the cavity depth to the aperture diameter.
	summary
	abstract	A method of making a joint between parts is provided, wherein the surface of at least one of the parts comprises aluminum oxide such as alpha aluminum oxide in the form of sapphire. A layer of aluminum nitride is provided between the surfaces of the parts where these contact. The method comprises the steps of bringing the parts into contact whereby the aluminum nitride layer is sandwiched between the parts and is in contact with the aluminum oxide surface, and performing localized heating of the aluminum nitride. The aluminum nitride is heated to at least the melting temperature of the aluminum nitride aluminum oxide eutectic, such that the aluminum nitride and adjacent aluminum oxide mix and melt to form an aluminum oxy-nitride bond. On cooling, the aluminum oxynitride forms a solid joint between the parts.
043274439	claims	1. A nuclear reactor core comprised of a number of moderator components and fuel components wherein said fuel component is comprised of capillary fuel elements created by the method of confining a liquid fuel in a horizontal capillary trough to which said liquid fuel is nonadhesive so that a meniscus of said liquid fuel projects above said capillary trough edge, and said capillary fuel elements are arranged in a geometric and spatial pattern with support to form said fuel components; said fuel components are arranged in a geometric and spatial pattern in relationship to said moderator components with sufficient separation maintained between said components to create channels for a coolant to circulate therein; and the combination of said moderator components, said coolant, and said fuel components comprises a critical mass. 2. A reactor core as claimed in 1, wherein said capillary fuel elements and said support are a single integral unit. 3. A reactor core as claimed in 1, wherein said capillary fuel elements, said support, and said moderator component are single integral unit. 4. A nuclear reactor comprised of a core as claimed in 1, a vessel that encloses said core and a neutron reflector that surrounds said core, an upper fuel reservoir located above said core, means to control and distribute fuel from said upper fuel reservoir to the inlets of the fuel elements in said core, a lower fuel reservoir below said core into which said fuel flows from said fuel elements, means to return fuel from said lower to said upper reservoir, and inlets and outlets for coolant in said vessel enclosing said core.
	description	1. Field of the Invention The present invention generally relates to a nuclear medical diagnostic device (an emission computed tomography (ECT) device), which applies an radioactive agent to a test subject, and simultaneously measures a γ-ray or a pair of γ-rays emitted by single photon radioactive isotopes (RIs) or positron RIs accumulated in a target portion of the test subject, so as to obtain a tomogram of the target portion. 2. Description of Related Art For a nuclear medical diagnostic device, that is, an ECT device, the single photon emission computed tomography (SPECT) device and positron emission tomography (PET) device are well known examples thereof. The SPECT device applies a radioactive agent including the single photon RIs to test subject, and detects the γ-ray emitted from a nuclide by using γ-ray detectors. The energy of the γ-ray emitted from the single photon RIs that are usually used during the inspection of the SPECT device is hundreds of keV. When the SPECT device is used, a single γ-ray is emitted; hence, an incident angle on the γ-ray detector cannot be obtained. Therefore, a collimator is used to detect only the γ-ray incident at a specific angle, so as to obtain the angle information. The detecting method of the SPECT device is as follows. A radioactive agent is applied to a test subject, and the γ-ray generated from the radioactive agent is detected, so as to specify a portion of the test subject where the radioactive agent is consumed relatively more (for example, the portion where cancer cells exist). The radioactive agent contains a material that tends to accumulate on specific tumors or molecules and the single photon RIs, such as Tc-99m, Ga-67, and Tl-201. The obtained data is converted to the data of each voxel through a filtered back projection method and the like. A half life of Tc-99m, Ga-67, and Tl-201 used in the SPECT device is six hours to three days longer than the half life of the RIs used in the PET device. In another aspect, the PET device applies a radioactive agent including positron RIs to the test subject, and detects an annihilation γ-ray generated by the positrons emitted from the nuclide by using the γ-ray detectors. Theoretically, the positrons may be combined with the electrons of adjacent cells and are annihilated, so the energy of the annihilation γ-ray generated by the positrons emitted from the positron RI used during the inspection of the PET device is fixed to be 511 keV. The annihilation γ-ray generated by the positrons may emit a pair of γ-rays. The detecting method of the PET device is as follows. The radioactive agent and a positron RI O-15, N-13, C-11, or F-18 are applied to the test subject, and the γ-rays generated from the radioactive agent are detected, so as to specify the portion of the test subject where the radioactive agent is consumed relatively more (for example, the portion where cancer cells exist). The radioactive agent includes the material that tends to accumulate on specific cells in the test subject. Fluorodeoxyglucose (2-[F-18]fluoro-2-deoxy-D-glucose, FDG) is an example of the radioactive agent. Through glycometabolism, FDG may be highly accumulated in the tumor tissue, so as to specify the tumor portion. The positrons emitted by the positron emitting nuclide contained in the radioactive agent and accumulated in the specific portion are combined with the electrons of adjacent cells, and are annihilated. A pair of γ-rays having the energy of 511 keV is emitted. The γ-rays are emitted to totally opposite directions from each other (180°±0.6°). If the pair of γ-rays is detected by the γ-ray detectors, it can be recognized that the positrons are emitted between which two γ-ray detectors. By detecting most of the pairs of γ-rays, the portion where the radioactive agent is consumed relatively more may be obtained. For example, as described above, the FDG may be accumulated in the cancer cells with the violent glycometabolism, such that cancer lesions may be found by the PET device. In addition, the obtained data is converted to a radioactive ray generation density of each voxel through the filtered back projection method, so as to pattern the generation position of the γ-ray (the position where the radioactive ray nuclide is accumulated, that is, the position of the cancer cells). O-15, N-13, C-11, and F-18 used in the PET device are RIs with the short half life from 2 min to 110 min. During the inspection of the PET device, the γ-ray generated when the positrons are annihilated is attenuated in the test subject, so absorption correction data used for the absorption correction must be obtained and the absorption correction data is used to perform the correction. The absorption correction data is as follows. For example, Cs-137 is used as an external ray source, the γ-rays from the external ray source are irradiated on the test subject and the transmission intensity is measured, so as to obtain the data of the attenuation ratio of the γ-ray in the test subject through calculation. The attenuation ratio of the γ-ray in the test subject is estimated by using the obtained absorption correction data, and the data obtained from the emission of the FDG is corrected to obtain a more accurate PET image. However, the existing nuclear medical diagnostic device has the following problems. That is, in order to improve the diagnostic accuracy, the agent using the nuclide emitting the single photons, an agent using the nuclide emitting the positrons, and other different agents must be simultaneously applied to the test subject. However, the agents cannot be detected and shot simultaneously under the situation. Further, the SPECT device and the PET device are independent from each other, so an expensive device for docking the SPECT device and the PET device docking is required. Accordingly, the present invention is directed to a nuclear medical diagnostic device, which is capable of simultaneously detecting and shooting an agent using a nuclide emitting single photons, an agent using a nuclide emitting positrons, and other different agents when the agents are applied to a test subject at the same time. As embodied and broadly described herein, the present invention has the following characteristic mechanisms. According to one aspect of the present invention, the nuclear medical diagnostic device includes a plurality of γ-ray detectors, a collimator, a collimator position detecting mechanism, a simultaneous measuring mechanism, an energy discriminating mechanism, a first position specifying mechanism, and a second position specifying mechanism. The plurality of γ-ray detectors is circularly disposed, and converts incident γ-rays to electric signals. The collimator is arranged along the front of the plurality of γ-ray detectors in a rotatable manner, and shields a part of single photons. The collimator position detecting mechanism detects a position of the collimator. The simultaneous measuring mechanism outputs the electric signals that are about simultaneously output from the plurality of γ-ray detectors as simultaneous measuring signals. The energy discriminating mechanism discriminates first signals and second signals among the electric signals output from the plurality of γ-ray detectors, in which the first signals are generated by the single photons emitted from a first agent accumulated in a test subject, and the second signals are generated by positrons emitted from a second agent accumulated in the test subject. The first position specifying mechanism specifies a position of the first agent accumulated in the test subject according to the first signals and the position of the collimator. The second position specifying mechanism specifies a position of the second agent accumulated in the test subject according to the simultaneous measuring signals and the second signals. Thus, the positions of the first agent and the second agent are simultaneously specified by using the above mechanisms. According to one aspect of the present invention, the collimator is a two-dimensional collimator. According to one aspect of the present invention, the collimator is a one-dimensional collimator, and includes ceptors arranged in the front of the plurality of γ-ray detectors. According to one aspect of the present invention, the energy discriminating mechanism further includes a scattered ray removing mechanism, which removes the signals that are about simultaneously measured by the two γ-ray detectors from the first signals, so as to reduce the influence due to the scattered ray of an annihilation γ-ray generated by positrons emitted from the second agent accumulated in the test subject. In the nuclear medical diagnostic device according to the present invention, even if the agent using the nuclide emitting single photons, agent using the nuclide emitting positrons, and other different agents are simultaneously applied to the detected body to improve a diagnostic accuracy, the agents can still be detected and shot simultaneously. The detectors having the SPECT function and the PET function are shared, so as to provide the detectors with a reasonable price. Only the collimator is rotated, and the γ-ray detectors are not required to move; hence, noise signals resulting from vibration are prevented. If the ceptors are disposed in the front of the detectors, the collimator is designed to be one dimensional. Therefore, the rotating collimator is light in weight, such that the collimator may be rotated by using a smaller driving mechanism. When the positron annihilation γ-ray is incident on the γ-ray detector as the γ-ray with the same energy as the single photons through Compton scattering, the positron annihilation γ-ray is discriminated as the electric signal caused by the single photons by the energy discriminating mechanism. However, a pair of annihilation γ-rays is emitted after the Compton scattering. Accordingly, by removing the simultaneously measured signals, a high quality image, in which the effect of the scattered ray is reduced, may be obtained. Further, by determining the types of the nuclides contained in the agents, portions of cancer cells where the FDG radioactive agent is accumulated are specified, and the diseased portions, except for the portions where the radioactive agent including the single photon RI is accumulated, are also specified. Reference will now be made in detail to the present embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts. The structure of a nuclear medical diagnostic device according to the first embodiment of the present invention is shown in the drawings and is described in the following. FIG. 1 is a cross-sectional view of a nuclear medical diagnostic device 1 of the present invention. It is assumed that in order to improve a diagnostic accuracy, an agent using a nuclide emitting single photons, an agent using a nuclide emitting positrons, and other different agents are simultaneously applied to a test subject 2 lying on a bed 7. FIG. 1 shows that an accumulation portion 11 of an agent with single photons emitting nuclide is present and shows an accumulation portion 21 of an agent with positrons emitting nuclide is present in the test subject 2. In this embodiment, it is assumed that the first agent includes the nuclide formed by Tc-99m emitting the single photons. The energy of the γ-ray of the nuclide is 141 keV, and the half life is 6 hours. In another aspect, it is assumed that the second agent includes the nuclide formed by FDG emitting the positrons. The nuclide emits the positrons, which are combined with the electrons of adjacent cells and are annihilated, and emits a pair of γ-rays having the energy of 511 keV. Further, the half life is 110 min. The nuclear medical diagnostic device of the present invention simultaneously shoots, patterns, and specifies the positions of the agents accumulated in the test subject. In this embodiment, a γ-ray detector 3 is used to detect both the agent using the nuclide emitting the single photons and the agent using the nuclide emitting the positrons. As described above, in order to detect a single photon γ-ray 12, a two-dimensional collimator 4 is required. Under the situation of the embodiment of FIG. 1, the two-dimensional collimator 4 is combined by a circular supporting means 5 residing on the entire periphery. The supporting means 5 is guided by a bearing 6 arranged on a seat frame 10, and may be rotated by using an external driving mechanism (not shown). Here, the two-dimensional collimator 4 is formed by a shielding material two-dimensionally combined in a lattice shape. The γ-ray detector 3 is formed by a γ-ray detector module 40. The γ-ray detector 3 is circularly disposed opposite to a regulated tomogram surface and is stacked for several layers along a body axis direction of the test subject 2. In another aspect, FIG. 2 is a front sectional view of the nuclear medical diagnostic device 1 of the present invention. The two-dimensional collimator 4 is arranged along the front of the γ-ray detector 3 in a rotatable manner, and the γ-ray detector 3 is circularly disposed opposite to the regulated tomogram surface. Further, the two-dimensional collimator 4 only resides on a part of the entire periphery, and is arranged at opposite positions. In this embodiment, the two-dimensional collimator is arranged at opposite positions, but the two-dimensional collimator is unnecessarily arranged at opposite positions. The two-dimensional collimator 4 is an indispensable part for detecting the single photon γ-ray 12. That is, when the two-dimensional collimator 4 rotates, at the moment the two-dimensional collimator 4 overlaps with the γ-ray detectors 3 which are circularly disposed relative to the regulated tomogram surface, the γ-ray detector 3A located in the overlap region functions together with the two-dimensional collimator 4, so as to detect the single photon γ-ray 12. All the γ-ray detectors 3 detect annihilation γ-rays 22 generated from the positrons. In addition, lead, tungsten, tungsten alloy, molybdenum, tantalum, and other heavy metals are used as the shielding material of the two-dimensional collimator 4. In this aspect of the invention, the γ-ray detector module 40 forming the γ-ray detector 3 is composed of scintillators, a light guide, and photomultipliers, in which the scintillators will emit light after the γ-rays emitted from the radioactive agent in the test subject are incident thereon. The light guide is used to specify the position, and the photomultipliers convert the light emitted by the scintillators to a pulse electric signal. In order to have a detailed description of the γ-ray detector module 40, an example is shown in FIGS. 3 and 4. FIG. 3 is an outside view in an X direction (side view) of the γ-ray detector module 40 observed from a Y direction, and FIG. 4 is an outside view in the Y direction (front view) of the γ-ray detector module 40 observed from the X direction. The γ-ray detector 3 is constructed with a scintillator array 42 (52), a light guide 46 (56), and four photomultipliers 61, 62, 63, and 64. The scintillator array 42 (52) has scintillators 41 (51) that are two-dimensionally and compactly arranged. The scintillators 41 (51) are divided by appropriately sandwiching light reflective materials 43 and 53, and 90 scintillators 41(51) are arranged in a manner of nine scintillators in the X direction and ten scintillators in the Y direction. The light guide 46 (56) is optically combined with the scintillator array 42 (52) and includes embedded lattice frames combined with light reflective materials 47 and 57, and is divided into a plurality of small areas. The four photomultipliers 61, 62, 63, and 64 are optically combined with the light guide 46 (56), respectively. In addition, the photomultipliers 61 and 62 are shown in FIG. 3, and the photomultipliers 63 and 64 are shown in FIG. 4. In this aspect of the invention, the scintillators 41 (51) apply, for example, inorganic crystals such as Gd2SiO5:Ce, Gd2SiO5:Ce doped with Zr, Lu2SiO5:Ce, LuYSiO5:Ce, LaBr3:Ce, LaCl3:Ce, LuI:Ce, Bi4Ge3O12, or Lu0.4Gd1.6SiO5:Ce etc. As shown in FIG. 3, when the γ-ray is incident on the nine scintillators 41 arranged in the X direction (in the X direction, the light reflective material 43 is sandwiched between every two scintillators 41), the γ-ray is converted to a visible light. The light is guided to the photomultipliers 61-64 through the optically combined light guide 46. Here, the position, length, and angle of each light reflective material 47 in the light guide 46 are adjusted, such that an output ratio of the photomultiplier 61 (63) and the photomultiplier 62 (64) arranged in the X direction is changed according to a fixed proportion. In more detail, if the output of the photomultiplier 61 is set to P1, the output of the photomultiplier 62 is set to P2, the output of the photomultiplier 63 is set to P3, and the output of the photomultiplier 64 is set to P4, the position and the length of the light reflective material 47 are set, such that a calculated value {(P1+P3)−(P2+P4)}/(P1+P2+P3+P4) representing a position in the X direction is changed according to the position of each scintillator 41 according to the fixed proportion. In another aspect, as shown in FIG. 4, for the ten scintillators 51 arranged in the Y direction (the light reflective material 53 is not sandwiched between the four scintillators 51 in the center, but is sandwiched between every two scintillators 51 except for the four scintillators 51 in the center), the situation is the same, the light is guided to the photomultipliers 61-64 through the optically combined light guide 56. In other words, the position and the length of each light reflective material 57 in the light guide 56 are set, and the angle is adjusted under an inclined situation, such that the output ratio of the photomultiplier 61 (62) and the photomultiplier 63 (64) arranged in the Y direction is changed according to the fixed proportion. In essence, the position and the length of the light reflective material 57 are set, such that a calculated value {(P1+P2)−(P3+P4)}/(P1+P2+P3+P4) representing a position in the Y direction is changed according to the position of each scintillator 51 based on the fixed proportion. In this aspect of the invention, the light reflective material 43 (53) between the scintillators 41 (51) and the light reflective material 47 (57) of the light guide 46 (56) may use a multi-layer film of silicon oxide and titanium oxide using a polyester film as a base material. A reflection efficiency of the multi-layer film is quite high, so it is used as a light reflective element. However, strictly speaking, a transmission component is generated according to the incident angle of the light, so the transmission component must also be calculated to decide the shapes and the arrangement of the light reflective material 43 (53) and the light reflective material 47(57). In addition, the scintillator array 42 (52) is bound with the light guide 46 (56) by using a coupling binding agent 44 (54), and the light guide 46 (56) is bound with the photomultipliers 61-64 by using a coupling binding agent 45 (55). Except for an optically combined surface with the photomultipliers 61-64, the peripheral surfaces not opposite to each scintillator 41 (51) are covered by the light reflective material. In this aspect of the invention, the light reflective material mainly uses a fluorine resin tape. FIG. 5 is a block diagram of a structure of a position operating circuit of the γ-ray detector. The position operating circuit is formed by adders 71, 72, 73, and 74, and position recognizing circuits 75 and 76. As shown in FIG. 5, in order to detect the incident position of the γ-ray in the X direction, the output P1 of the photomultiplier 61 and the output P3 of the photomultiplier 63 are input to the adder 71, and the output P2 of the photomultiplier 62 and the output P4 of the photomultiplier 64 are input to the adder 72. Each added output (P1+P3) and (P2+P4) of the two adders 71 and 72 is input to the position recognizing circuit 75. According to the two added outputs, the incident position of the γ-ray in the X direction is obtained. Similarly, in order to detect the incident position of the γ-ray in the Y direction, the output P1 of the photomultiplier 61 and the output P2 of the photomultiplier 62 are input to the adder 73, and the output P3 of the photomultiplier 63 and the output P4 of the photomultiplier 64 are input to the adder 74. Each added output (P1+P3) and (P2+P4) of the two adders 73 and 74 is input to the position recognizing circuit 76. According to the two added outputs, the incident position of the γ-ray in the Y direction is obtained. Further, the calculated value (P1+P2+P3+P4) represents the energy relative to the event, and is shown as the energy spectrum in FIG. 6. Then, referring to FIGS. 7-9, the structure for detecting the annihilation γ-ray generated by the positrons and the single photon γ-ray is described in detail. FIG. 7 is a schematic block diagram of the process for detecting the annihilation γ-ray generated by the positrons and the single photon γ-ray. In this aspect of the invention, it is assumed that N γ-ray detectors 3 are installed in the device. The electric signals Sn (n=1, 2, . . . N) output from all the γ-ray detectors 3 are output to an energy discriminating mechanism 81. As shown in FIG. 8, in the energy discriminating mechanism 81, an energy window centered at 141 keV (for example, ±100 keV) is set on the energy spectrum, and the signals entering the energy window are output as first signals S1n. As shown in FIG. 9, an energy window centered at 511 keV (for example, ±100 keV) is set on the energy spectrum, and the signals entering the energy window are output as second signal S2n. The first signals S1n output from the energy discriminating mechanism 81 are input to a first position specifying mechanism 82. The first position specifying mechanism 82 outputs a signal S1 used to specify the position of the first agent. As shown in FIGS. 1 and 2, in order to specify the position of the first agent, the single photon γ-ray 12A passing through the rotating two-dimensional collimator 4 and reaching the γ-ray detector 3A must be used as the single photon γ-ray for detection. In one aspect of the invention, the position of the two-dimensional collimator 4 is detected in sequence by using a collimator position detecting mechanism (not shown). Therefore, a detector selecting mechanism 821 is disposed. The detector selecting mechanism 821 divides the first signals S1n output from the energy discriminating mechanism into signals S1A from the γ-ray detector 3A overlapping the two-dimensional collimator 4 and signals S1B from the γ-ray detector 3B not overlapping the two-dimensional collimator 4, and outputs the signals S1A and S1B. When the collimator 4 is rotated, the signals S1A are counted, so as to correctly specify the accumulation portion 11 of the first agent. However, as shown in FIG. 2, a Compton scattered ray 22D presents in the annihilation γ-ray 22 starting from the accumulation portion 21 of the second agent. The Compton scattered ray 22D also causes Compton scattering in the test subject 2 as the annihilation γ-ray 22C does, changes the traveling path, and reduces the energy, and is then emitted. The Compton scattered ray 22D has, for example, the energy of approximately 141 keV, and reaches the γ-ray detector 3A after passing through the rotating two-dimensional collimator 4. At this time, the accumulation portion 21 of the second agent may be mistaken as the accumulation portion of the first agent. In order to solve the problem, it is preferably for a scattered ray removing mechanism 822 to be disposed in the first position specifying mechanism 82. In the scattered ray removing mechanism 822, the signals S1A and S1B are input, signals S1AB entering the time window (for example, within 6 ns) are detected by a simultaneous measuring mechanism 823, and the signals S1AB are removed from the signals S1A. Through the process, the effect of the annihilation γ-ray with its energy reduced after the Compton scattering may be eliminated. In another aspect, the second signals S2n output from the energy discriminating mechanism 81 are input to a second position specifying mechanism 83. The second position specifying mechanism 83 has a function of specifying the position of the second agent. The second position specifying mechanism 83 extracts the signals S2 measured simultaneously by a simultaneous measuring mechanism 831 at two positions. The simultaneous measuring mechanism 831 extracts the signals entering the time window (for example, within 6 ns) as the annihilation γ-ray signals S2. According to the two positions of the signals where the signals are observed, the position of the second agent is specified. In this manner, the energy discriminating mechanism 81 extracts the signals S1n and S2n with the required energy from the signals S1n output from all the γ-ray detectors, and the simultaneous measuring mechanism 831 of the annihilation γ-ray detecting mechanism 83 extracts the signals related the annihilation γ-rays approximately 180° opposite to each other and emitted in pairs. In one aspect of the invention, it may also be considered that a part of the annihilation γ-rays 22 that should be incident on the γ-ray detector 3A originally is shielded by the two-dimensional collimator 4. However, the energy of the annihilation γ-ray 22 is greater than 511 keV, so the annihilation γ-rays 22 may pass through the two-dimensional collimator 4. According to the material of the collimator 4, a fixed amount of annihilation γ-rays 22B are shielded according to a certain probability. As described above, the nuclear medical diagnostic device of the present invention may simultaneously shoot, pattern, and specify the positions of the agents accumulated in the test subject. In the present invention, the γ-ray detector 3 is used to detect both the agent using the nuclide emitting the single photons and the agent using the nuclide emitting the positrons. The nuclear medical diagnostic device according to the second embodiment of the present invention is described in the following. FIG. 10 is a cross-sectional view of the nuclear medical diagnostic device according to the second embodiment of the present invention. Similar to the first embodiment, it is assumed that an agent using a nuclide emitting single photons, an agent using a nuclide emitting positrons, and other different agents are simultaneously applied to a test subject 2 lying on a bed 7 to improve the diagnostic accuracy. FIG. 10 shows that an accumulation portion 11 having the agent using the nuclide emitting the single photons and an accumulation portion 21 having the agent using the nuclide emitting the positrons exist in the test subject 2. As described above, in order to detect the single photon γ-ray 12, a two-dimensional collimator is required. Under the situation of the second embodiment of FIG. 10, ceptors 23 are arranged on the whole periphery in the front of the γ-ray detector 3, so as to perform the two dimensional collection during the detection of the positrons. In another aspect, a one-dimensional collimator 24 is combined by a circular supporting means 5 configured on the whole periphery. The supporting means 5 is guided by a bearing 6 arranged on a seat frame 10, and may be rotated by an external driving mechanism (not shown). The one-dimensional collimator 4 has a shielding material arranged in a direction. In other words, the part on which the ceptors 23 and the one-dimensional collimator 24 are combined forms the two dimensional collimator. In addition, the γ-ray detector 3 is formed by a γ-ray detector module 40, the γ-ray detector 3 is circularly disposed opposite to a regulated tomogram surface and is stacked for several layers along a body axis direction of the test subject 2. In another aspect, FIG. 11 is a front sectional view of the nuclear medical diagnostic device 1 of the present invention. The one-dimensional collimator 24 of FIG. 11 may be rotated along the front of the γ-ray detector 3, and the γ-ray detector 3 is circularly disposed opposite to the regulated tomogram surface. Further, the one-dimensional collimator 24 only resides on a part of the entire periphery, and is arranged, for example, in opposite positions. The ceptors 23 and the one-dimensional collimator 24 form the two dimensional collimator, so as to detect the single photon γ-ray 12. In other words, when the one-dimensional collimator 24 is rotated, a γ-ray detector 3A located in an instant area where the γ-ray detector 3 is overlapped, the ceptors 23 and the one-dimensional collimator 24 function together, so as to detect the single photon γ-ray 12, in which the γ-ray detector 3 is circularly disposed opposite to the regulated tomogram surface. All the γ-ray detectors 3 detect annihilation γ-rays 22 generated from the positrons. In one aspect of the invention, the γ-ray detector module 40 forming the γ-ray detector 3 is composed of scintillators, a light guide, and photomultipliers, in which the scintillators will emit light after the γ-rays emitted from the radioactive agent in the test subject are incident thereon, the light guide is used to specify the position, and the photomultipliers convert the light emitted by the scintillators to a pulse electric signal. The details of this embodiment are the same as those of the first embodiment. Then, in order to detect the accumulation portions of the agents, the annihilation γ-ray and the single photon γ-ray must be totally discriminated for detection, and the details are the same as those of the first embodiment. The present invention is applicable to the following nuclear medical diagnostic device (ECT device). The nuclear medical diagnostic device is used to simultaneously measure a γ-ray or a pair of γ-rays emitted by the single photon radioactive isotopes (RIs) or the positron RIs accumulated in the test subject, so as to obtain a tomogram of the target portion. It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.
054769892	description	The following examples are provided to further illustrate the present invention. It is to be understood, however, that the examples are presented for purpose of illustration only and are not intended as limiting the invention. Unless otherwise indicated, all parts, percents, ratios and the like are by weight. EXAMPLE 1 A 1 liter capacity beaker was charged with 30 ml of plutonium-bearing liquid waste adjusted to pH 1.6 having a uranium (referred to as "U" hereinafter) concentration of 3.3.times.10.sup.-2 mg/ml and a plutonium (referred to as "Pu" hereinafter) concentration of 3.18.times.10.sup.-3 mg/ml and then with 1.0 g of a fibrous active carbon preparation (manufactured by UNITIKA, LTD. under the trade name of A-20; specific surface area, 2,100 m.sup.2 /g; ignition point, 480.degree. C.; equilibrium moisture regain, 11% at a relative humidity of 45%), and the resulting mixture was subjected to an adsorption treatment at a temperature of 25.degree. C. for 24 hours. This fibrous active carbon adsorbed Pu in an amount of 9.4.times.10.sup.-2 mg/g, with an adsorption percentage of 99%. After the adsorption treatment, the spent fibrous active carbon was dehydrated, dried and then put in a melting pot for incineration for 3 hours of at 600.degree. C. When burned, the fibrous active carbon became red but emitting no flames, and its quantity decreased over time. The residue after incineration was only about 1 mg, and no scattering of radioactive materials was detected. EXAMPLE 2 A 94 g portion of phenol was put in a 5 liter capacity beaker. With stirring, to this was gradually added 170 g of 98% concentrated sulfuric acid while keeping the phenol temperature at 50.degree. C. or below. To the resulting mixture was further added 9 ml of 37% formaldehyde in the same method, followed by 1 hour of reaction at 70.degree. C. The resulting reaction solution was immediately cooled to room temperature (about 20.degree.-30.degree. C.). To a 72 g portion of the reaction solution was added a mixture of 17.4 g phosphorous acid and 6.2 g ion-exchanged water with stirring, followed by the addition of 74 ml of 37% formaldehyde in the same method. The resulting solution was diluted with 300 ml of water and then mixed with 30 g of a fibrous active carbon preparation (manufactured by UNITIKA, LTD. under the trade name of A-20; specific surface area, 2,110 m.sup.2 /g). After allowing the fibrous active carbon to contact the reaction solution thoroughly, 9.9 ml of diethylenetriamine was immediately added to the mixture. After 3 hours of reaction at 80.degree. C., the liquid portion of the reaction mixture was removed, and the remaining reaction product was washed with water and then dried at 100.degree. C. for 1.5 hours to obtain a fibrous active carbon preparation (Sample A) to which aminomethylphosphonic acid functional groups had been added. Sample A had a specific surface area of 1,014 m.sup.2 /g, an ignition point of 480.degree. C. and an equilibrium moisture regain of 43% at a relative humidity of 45%. A 1 g portion of Sample A was placed in a 1 liter capacity beaker containing 80 ml of the same plutonium-bearing liquid waste as described in Example 1, and the adsorption treatment of Example 1 was repeated. Sample A adsorbed Pu in an amount of about 2.3.times.10.sup.-1 mg/g, with an adsorption percentage of 90%. After the adsorption treatment, the spent Sample A was dehydrated, dried and then placed in a melting pot for incineration at 600.degree. C. for 3 hours. When burned, similar to the case of the fibrous active carbon, Sample A became red but with no emission of flames, and its quantity decreased over time. The residue after the incineration was about 1 mg or less, and no scattering of radioactive materials was detected. COMPARATIVE EXAMPLE 1 An adsorption treatment of plutonium-bearing liquid waste was carried out in the same method as described in Example 2, except that 1.0 g of a commercially available coconut shell active carbon preparation (granular; specific surface area, 800 m.sup.2 /g; ignition point, 510.degree. C.) was used. The granular active carbon adsorbed Pu in an amount of about 4.3.times.10.sup.-2 mg/g, with an adsorption percentage of 17%. After the adsorption treatment, the spent granular active carbon was dehydrated, dried and then placed in a melting pot for incineration at 600.degree. C. for 3 hours. The granular active carbon burned with the emission of flames. About 35 mg of material remained after the incineration as the burning residue of the active carbon, and scattering of radioactive materials was detected around the melting pot. COMPARATIVE EXAMPLE 2 An adsorption treatment of plutonium-bearing liquid waste was carried out in the same method as described in Example 2, except for the use of 1.0 g of a commercially available chelate resin with aminomethylphosphonic acid functional groups (Unicelec UR-3100, manufactured by UNITIKA, LTD.). The chelate resin adsorbed Pu in an amount of 2.0.times.10.sup.-1 mg/g, with an adsorption percentage of 78%. After the adsorption treatment, the spent chelate resin was dehydrated and placed in a melting pot for incineration at 900.degree. C. for 5 hours. The chelate burned giving forth smoke and flames. About 90 mg of materials remained after the incineration as a foamed carbonized residue which stuck fast to the wall of the melting pot, thus showing extreme difficulty in carrying out the waste treatment. In addition, a large amount of scattering of radioactive nuclides was detected around the melting pot. EXAMPLE 3 A glass column having an inside diameter of 14.8 mm and a height of 500 mm was packed with 9.0 g of a fibrous active carbon preparation (manufactured by UNITIKA, LTD. under the trade name of A-20; specific surface area, 2,100 m.sup.2 /g; ignition point, 480.degree. C.; equilibrium moisture regain, 11% at a relative humidity of 45%). The resulting packed layer had a height of 400 mm. A 400 ml portion of plutonium-bearing liquid waste having a U concentration of 0.26 mg/ml and a Pu concentration of 3.9.times.10.sup.-5 mg/ml was passed through the thus prepared column at a flow rate of 176 ml/hr. As a result, the packed fibrous active carbon adsorbed 10.0.times.10.sup.-3 mg of Pu with an adsorption percentage of 64%, and 46 mg of U with an adsorption percentage of 44%. After the adsorption treatment, the spent fibrous active carbon was dehydrated, dried and then placed in a melting pot for 3 hours of incineration at 550.degree. C. When burned, the fibrous active carbon became red but emitting no flames, and its quantity decreased over time. The residue after the incineration was about 47 mg, and no scattering of radioactive materials was detected. EXAMPLE 4 The column process of the plutonium-bearing liquid waste of Example 3 was repeated except that Sample A prepared in Example 2 was used as the adsorbent. As a result, the packed Sample A adsorbed 10.0.times.10.sup.-3 mg of Pu with an adsorption percentage of 64%, and 40 mg of U with an adsorption percentage of 39%. After the adsorption treatment, spent Sample A was dehydrated, dried and then placed in a melting pot to for 3 hours of incineration at 600.degree. C. When burned, similar to the case of the fibrous active carbon, Sample A became red but emitting no flames, and its quantity decreased over time. The residue after the incineration was about 41 mg, and no scattering of radioactive materials was detected. EXAMPLE 5 A 3 g portion of a fibrous active carbon preparation (manufactured by UNITIKA, LTD. under the trade name of A-20; specific surface area, 2,116 m.sup.2 /g) was placed in an electric furnace controlled at 600.degree. C. and subjected to 10 minutes of oxidation reaction to obtain an oxidized active carbon adsorbent. The thus obtained adsorbent was found to have a specific surface area of 2,071 m.sup.2 /g, an ignition point of 480.degree. C. and an equilibrium moisture regain of 53% at a relative humidity of 45%. A 0.25 g portion of the adsorbent was soaked in 50 ml of Pu solution having a Pu concentration of 5.0.times.10.sup.-3 mg/ml and an acid concentration of 1.0N, followed by 120 hours of adsorption treatment. As a result, a Pu-adsorption percentage of 96.1% was obtained. After the adsorption treatment, the spent fibrous active carbon was dehydrated, dried and then placed in a melting pot to for 3 hours of incineration at 600.degree. C. When burned, the fibrous active carbon became red but emitting no flames, and its quantity decreased over time. The residue after the incineration was 1 mg or less, and no scattering of radioactive materials was detected. EXAMPLE 6 A 8 g portion of polyethyleneimine having a molecular weight of 600 (Epomin PEI-600, manufactured by Japan Catalytic Chemical Industry Co., Ltd.) was dissolved in 4.5 liters of ion-exchanged water, and 100 g of a fibrous active carbon preparation (manufactured by UNITIKA, LTD. under a trade name of A-20; specific surface area, 2,110 m.sup.2 /g) was soaked in the polyethyleneimine solution. After standing for 4 hours, 3 g of carbon disulfide was added to the resulting mixture and the mixture was gently stirred at room temperature. When emulsion state of the liquid phase disappeared, the temperature of the mixture was increased to 80.degree. C. and the reaction was continued for 4 hours. After removing the liquid portion, the resulting reaction product was washed thoroughly with hot water and then dried at 50.degree. C. for 4 hours to obtain an adsorbent to which polyethyleneimine functional groups have been added. The thus obtained adsorbent was found to have a specific surface area of 1,420 m.sup.2 /g, an ignition point of 480.degree. C. and an equilibrium moisture regain of 48% at a relative humidity of 45%. An adsorption treatment of a Pu solution was carried out in the same method as in Example 5 except that 0.25 g of the thus obtained adsorbent was used. As a result, a Pu-adsorption percentage of 88.3% was obtained. After the adsorption treatment of the functional group-added adsorbent, the spent adsorbent was dehydrated, dried and then placed in a melting pot for 3 hours of incineration at 600.degree. C. When burned, the functional group-added adsorbent became red but emitting no flames, and its quantity decreased over time. The residue after the incineration was 1 mg or less, and no scattering of radioactive materials was detected. EXAMPLE 7 A 94 g portion of phenol was placed in a 5 liter capacity beaker. With stirring, to this was gradually added 170 g of 98% concentrated sulfuric acid while keeping the phenol temperature at 50.degree. C. or below. To the resulting mixture was further added 9 ml of 37% formaldehyde in the same method, followed by 1 hour of reaction at 70.degree. C. The resulting reaction solution was immediately cooled to room temperature. To a 8.7 g portion of the reaction solution was added a mixture of 2.1 g phosphorous acid and 0.75 g ion-exchanged water with stirring, followed by the addition of 9.0 ml of 37% formaldehyde in the same method. The resulting solution was diluted with 1,500 ml of water and then mixed with 30 g of a fibrous active carbon preparation (manufactured by UNITIKA, LTD. under the trade name of A-20; specific surface area, 2,110 m.sup.2 /g). After allowing the fibrous active carbon to contact thoroughly the reaction solution, 1.2 ml of diethylenetriamine was immediately added to the mixture. After 3 hours of reaction at 80.degree. C., the liquid portion of the reaction mixture was removed, and the remaining reaction product was washed with water and then dried at 125.degree. C. for 2 hours to obtain a fibrous active carbon preparation to which aminomethylphosphonic acid functional groups had been added. The thus obtained adsorbent showed a specific surface area of 1,280 m.sup.2 /g, an ignition point of 480.degree. C. and an equilibrium moisture regain of 41% at a relative humidity of 45%. An adsorption treatment of a Pu solution was carried out in the same method as in Example 5 except that 0.25 g of the thus obtained adsorbent was used. As a result, a Pu-adsorption percentage of 86.8% was obtained. After the adsorption treatment of the functional group-added adsorbent, the spent adsorbent was dehydrated, dried and then placed in a melting pot for 3 hours of incineration at 600.degree. C. When burned, the functional group-added adsorbent became red but with no emission of flames, and its quantity decreased over time. The residue after the incineration was about 1 mg or less, and no scattering of radioactive materials was detected. COMPARATIVE EXAMPLE 3 An adsorption treatment of a plutonium-bearing solution was carried out in the same method as described in Example 5, except that a fibrous active carbon preparation (A-10, manufactured by UNITIKA, LTD.) having a specific surface area of 950 m.sup.2 /g, an ignition point of 480.degree. C. and an equilibrium moisture regain of 31% at a relative humidity of 45% was used as the adsorbent. As a result, the adsorption percentage of Pu was found to be only 60%. COMPARATIVE EXAMPLE 4 A 10 g portion of a fibrous active carbon preparation (manufactured by UNITIKA, LTD. under the trade name of A-20; specific surface area, 2,116 m.sup.2 /g) was placed in an electric tube furnace. On passing hydrogen gas through the furnace at a flow rate of 75 ml/min, the temperature of the furnace was increased to 900.degree. C. at a rate of increase of 300.degree. C./hr and the fibrous active carbon was subjected to 15 minutes of a reduction treatment at the same final temperature. The reduction-treated active carbon adsorbent thus obtained had a specific surface area of 2,060 m.sup.2 /g, an ignition point of 480.degree. C. and an equilibrium moisture regain of 0.9% at a relative humidity of 45%. An adsorption treatment of a plutonium-bearing solution was carried out in the same method as described in Example 5, except that the thus obtained adsorbent was used. As a result, the adsorption percentage of Pu was found to be only 50%. Thus, it is apparent that, in accordance with the present invention, an adsorbent useful for the selective adsorption of radioactive nuclides, as well as a process for the volume reduction of radioactive waste that contains radioactive nuclides are provided. Since the adsorbent of the present invention which comprises a fibrous active carbon system having an inorganic framework and a specific surface area of 1,000 m.sup.2 /g or more has a hydrophilic property due to its oxidation treatment, etc. the adsorbent of the present invention possesses excellent durability against radiation and adsorbs transuranium elements selectively. As a consequence, the use of the inventive adsorbent in the treatment process of radioactive liquid waste renders possible the selective and secure separation and removal of trace amounts of plutonium and the like from the radioactive liquid waste. Also, according to the present invention, the volume of radioactive nuclides-adsorbed waste can be reduced significantly and scattering of radioactive nuclides at the time of incineration can be prevented, without a problem of securing extra storage space due to increased amounts of waste occurring. While the invention has been described in detail and with reference to specific embodiments thereof, it will be apparent to one skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope thereof.
053352599	description	DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the present invention which is applied to an X-ray exposure apparatus. Synchrotron radiation light (X-ray) 2 emitted from the emission point 1 of a charged particle accumulation ring is expanded by a fixed mirror 3 having a convex reflection surface, in a direction (y-axis direction) perpendicular to the orbit plane of the accumulation ring. After passing through an X-ray pickup window having a beryllium film (X-ray transmission film) 4, it is introduced into a reduced pressure chamber (not shown) having a reduced pressure ambience of helium gas. Then, it passes an aperture 5a of a shutter and impinges on a mask 6, whereby a mask pattern of the mask 6 is printed on a wafer (substrate) 7. The synchrotron radiation X-rays 2a expanded in the y-axis direction by the mirror 3 have an intensity distribution such as shown in FIG. 2. That is, it is even in a direction (x-axis direction) perpendicular to the y-axis direction, but in the y-axis direction it has a distribution with a peak at its central portion. In order to avoid non-uniform exposure of the wafer 7 resulting from such an intensity distribution, the movement of the shutter 5 is controlled in accordance with displacement curves shown in FIG. 3. FIG. 3 illustrates the y-axis positions of the upper edge (hereinafter "leading shutter") 51 and the lower edge (hereinafter "trailing shutter") 52 of the aperture 5a as the shutter 5 moves in the y-axis direction as depicted by an arrow, in relation to the time period from start to end of the exposure operation. Displacement of the leading shutter 51 is depicted by displacement curve 51a, while displacement of the trailing shutter 52 is depicted by displacement curve 52a. The amount of exposure at a given position within a width L.sub.0, in the y-axis direction, of the exposure region of the wafer 7 is determined by the product of the exposure period .DELTA.t, from the moment when the opening 5a of the shutter is opened with the leading shutter 51 to the moment when the opening is closed with the trailing shutter 52, with the intensity of synchrotron radiation X-rays at that position. Thus, by changing the exposure period .DELTA.t in accordance with the intensity distribution, it is possible to cancel the non-uniformness of exposure. Since, however, as the expanded synchrotron radiation X-rays 2a pass through the beryllium film 4, the intensity distribution changes due to non-uniform X-ray absorption resulting from non-uniform thickness of the film 4, and there is still a possibility of non-uniform exposure. In consideration of this, an appropriate direction of thickness change is selected in the distribution of non-uniformness in thickness of the beryllium film 4, and the film is so disposed that the selected direction is aligned with the y-axis direction. Further, the displacement curve of the shutter is so modified as to compensate for the non-uniformness in thickness concurrently. As an example, when a beryllium film 41 of a thickness of 25 microns having a substantially one-dimensional distribution such as shown in FIG. 4 is used, it may be so placed that the direction (direction of center line A.sub.2 -B.sub.2) in which the thickness substantially is unchanged, is aligned with the x-axis direction and that the area as depicted by solid line 41a is used as the X-ray pickup portion. The synchrotron radiation X-rays passed through such a beryllium film 4 having a thickness distribution as described above, have an intensity distribution as illustrated in FIG. 5 which is substantially even in the x-axis direction and which changes only in the y-axis direction. Thus, by correcting the displacement curves 51a and 52a of the shutter 5 on the basis of the intensity distribution of FIG. 5 and by controlling the movement of the shutter 5 in accordance with corrected displacement curves 51b and 52b (see FIG. 3), it is possible to reduce non-uniform exposure due to non-uniform thickness of the beryllium film 4, considerably. It has been confirmed that the non-uniform exposure of the wafer 7 due to non-uniform thickness of the beryllium film 4 can be reduced to about 0.5%, by controlling the movement of the shutter 5 in accordance with the thus corrected displacement curves 51b and 52b. When as a comparative example the beryllium film 41 as aforementioned is disposed so that the center line A.sub.1 -B.sub.1 is aligned with the x axis and that the area as depicted by a broken line 41b is used as the X-ray pickup portion, the synchrotron radiation X-rays passed through the beryllium film have an intensity distribution as shown in FIG. 6 which is uneven in the x-axis direction. Thus, a non-uniformness of wafer exposure of about 10.4% results from the non-uniform thickness of the beryllium film. It has been confirmed that, even if the displacement curves of the shutter are corrected while taking into account the non-uniformness in thickness of the beryllium film, non-uniformness of exposure of about 8.1% remains. The direction of substantially one-dimensional thickness distribution of the beryllium film 41 may be detected in the manner to be described below. As shown in FIG. 7, an X-ray pickup area may be defined provisionally on the beryllium film 41. Then, the area may be divided regularly by sixteen dividing lines along the center line A.sub.3 -B.sub.3 and by fifteen dividing lines along a direction perpendicular to the center line. At each intersection of such dividing lines, the thickness of the beryllium film 41 may be measured, by which the thickness distribution of the beryllium film 41 may be determined. From the thus obtained thickness distribution, an average of measured values of thickness along each row extending perpendicularly to the center line A.sub.3 -B.sub.3 may be determined by calculation, by which the thickness distribution along the center line A.sub.3 -B.sub.3 is determined. Thereafter, with regard to each of the different straight lines each intersecting the center line A.sub.3 -B.sub.3 at a predetermined angle, an X-ray pickup area may be defined provisionally and an average of measured values of film thickness may be determined by calculation, by which film thickness distributions with respect to different directions intersecting the center line A.sub.3 -B.sub.3 are determined. Among these directions, such a one as having a largest film thickness distribution may be selected. Then, the beryllium film may be disposed in that direction and the displacement curves of the shutter may be corrected in accordance with the average film thickness distribution along the center line. Also, when an X-ray transmission film has a two-dimensional non-uniformness of thickness such as shown in FIG. 8, film thickness distributions may be measured in accordance with the method described above, and such a direction as having a smallest dispersion of non-uniformness of film thickness in rows intersecting the center line may be selected as the direction of disposition of the X-ray transmission film. Further, when an X-ray transmission film is so large as compared with the X-ray pickup portion that the center line C of the X-ray pickup portion can be set off the center of the X-ray transmission film, some arrangements in which the center C is shifted or deviated in different directions, within an admittable range, may be considered provisionally and the film thickness distributions of corresponding X-ray pickup areas 42a, 42b, etc., may be measured. Then, the X-ray transmission film may be disposed so that, among all the measured film thickness distributions, the portion as having the smallest dispersion of film thickness distributions is in the rows which intersect the center line perpendicularly. Furthermore, when an X-ray transmission film comprises a laminated film 43 such as shown in FIG. 9 wherein it has a layered structure of thin film layers 43a and 43b of a beryllium film and a polyimide film, the X-ray transmissivity of the laminated thin film may be measured directly. Subsequently, on the basis of this and in a similar manner as described, the direction and position of maximum non-uniformness of X-ray transmissivity or, alternatively, those of small dispersion of film thickness distributions of the rows intersecting the center line perpendicularly, may be determined. Then, the X-ray transmission film may be so disposed that the determined direction is aligned with the x-axis direction, and it may be used as the X-ray pickup window. The direction of disposition of a beryllium film may be determined by measuring the X-ray transmissivity distribution of the film. On that occasion, in place of measuring the film thickness as described, the X-ray transmissivity of the beryllium film may be measured and such a direction as having a largest distribution of X-ray transmissivity change may be determined. Then, the beryllium film may be disposed along the thus determined direction. If some mark or feature for identification of the direction or position for the disposition of the film is provided on the X-ray transmission film itself or on a holder for supporting the film, then the mounting of the X-ray transmission film is facilitated significantly. Also, when a rotating or moving mechanism is added to the X-ray transmission film or to a holder supporting the film, it is very easy to correctly dispose the same without demounting the film. Particularly, in a case when an X-ray detector is provided on a mask stage or a wafer stage, the intensity distribution of the X-rays passed through the transmission film may be measured by such an X-ray detector and, on the basis of the measurement, the X-ray transmission film may be rotated or moved by the rotating or moving mechanism to an appropriate position. While in the above-described embodiment the moving speed of the shutter is controlled to attain uniform exposure on different portions of the wafer some other structures may be adopted. For example, the mask 6 and the wafer 7 may be moved as a unit so that they may be scanned with the synchrotron radiation X-rays. By controlling the scanning speed, the amount of exposure on different portions of the wafer can be made uniform. Alternatively, the mirror 3 may be made swingable, and the swinging speed may be adjusted to adjust the amount of exposure on different portions of the wafer. While in the foregoing the invention has been described with reference to an X-ray exposure apparatus, the invention is not limited to this but it is applicable also to an apparatus, such as an X-ray CVD apparatus, for example, wherein an X-ray transmission film is used and wherein uniform illumination is required. Now, an embodiment of a semiconductor device manufacturing method according to the present invention which uses an exposure apparatus as having been described in the foregoing, will be explained. FIG. 10 is a flow chart of the sequence of manufacturing a semiconductor device such as a semiconductor chip (e.g. IC or LSI), a liquid crystal panel or a CCD, for example. Step 1 is a design process for designing the circuit of a semiconductor device. Step 2 is a process for manufacturing a mask on the basis of the circuit pattern design. Step 3 is a process for manufacturing a wafer by using a material such as silicon. Step 4 is a wafer process which is called a pre-process wherein, by using the so prepared mask and wafer, circuits are practically formed on the wafer through lithography. Step 5 subsequent to this is an assembling step which is called a post-process wherein the wafer processed by step 4 is formed into semiconductor chips. This step includes assembling (dicing and bonding) and packaging (chip sealing). Step 6 is an inspection step wherein operability check, durability check and so on of the semiconductor devices produced by step 5 are carried out. With these processes, semiconductor devices are finished and they are shipped (step 7). FIG. 11 is a flow chart showing details of the wafer process. Step 11 is an oxidation process for oxidizing the surface of a wafer. Step 12 is a CVD process for forming an insulating film on the wafer surface. Step 13 is an electrode forming process for forming electrodes on the wafer by vapor deposition. Step 14 is an ion implanting process for implanting ions to the wafer. Step 15 is a resist process for applying a resist (photosensitive material) to the wafer. Step 16 is an exposure process for printing, by exposure, the circuit pattern of the mask on the wafer through the exposure apparatus described above. Step 17 is a developing process for developing the exposed wafer. Step 18 is an etching process for removing portions other than the developed resist image. Step 19 is a resist separation process for separating the resist material remaining on the wafer after being subjected to the etching process. By repeating these processes, circuit patterns are superposedly formed on the wafer. While the invention has been described with reference to the structures disclosed herein, it is not confined to the details set forth and this application is intended to cover such modifications or changes as may come within the purposes of the improvements or the scope of the following claims.
	claims	1. An exposure apparatus for a charged particle beam, comprising: a pattern information acquiring section acquiring information on a character projection pattern formed in a character projection aperture mask; a first information storing section storing a plurality of pieces of information on reference patterns; and an identifying section identifying a shape of the character projection pattern as a shape of one of the reference patterns by comparing the information on the character projection pattern with the pieces of information on the reference patterns. 2. The apparatus according to claim 1 , further comprising a pattern information generating section generating information on a shape and a placement of the character projection pattern based on information on the identified shape of the character projection pattern. claim 1 3. The apparatus according to claim 2 , further comprising a second information storing section storing the information on the shape and the placement of the character projection pattern generated by the pattern information generating section. claim 2 4. The apparatus according to claim 1 , further comprising a pattern information correcting section correcting the information on the reference pattern based on information on the identified shape of the character projection pattern. claim 1 5. The apparatus according to claim 4 , further comprising a second information storing section storing information on the reference pattern corrected by the pattern information correcting section. claim 4 6. The apparatus according to claim 1 wherein the information on the character projection pattern is acquired by detecting a reflection electron, a secondary electron, or a transmission electron of the charged beam with which the character projection aperture mask is irradiated. claim 1 7. The apparatus according to claim 1 wherein the information on the character projection pattern is acquired by imaging the character projection pattern formed in the aperture mask. claim 1 8. An exposure method for a charged beam, comprising: acquiring information on a character projection pattern formed in a character projection aperture mask; and identifying a shape of the character projection pattern as a shape of one of a plurality of reference patterns by comparing the information on the character projection pattern with a plurality of pieces of information on the reference patterns. 9. The method according to claim 8 , further comprising generating information on a shape and a placement of the character projection pattern based on information on the identified shape of the character projection pattern. claim 8 10. The method according to claim 9 , further comprising storing the information on the shape and the placement of the character projection pattern. claim 9 11. The method according to claim 8 , further comprising correcting the information on the reference pattern based on information on the identified shape of the character projection pattern. claim 8 12. The method according to claim 11 , further comprising storing the corrected information on the reference pattern. claim 11 13. The method according to claim 8 wherein the information on the character projection pattern is acquired by detecting a reflection electron, a secondary electron, or a transmission electron of the charged beam with which the character projection aperture mask is irradiated. claim 8 14. The method according to claim 8 wherein the information on the character projection pattern is acquired by imaging the character projection pattern formed in the aperture mask. claim 8 15. A manufacturing method of a semiconductor device comprising: acquiring information on a character projection pattern formed in a character projection aperture mask; identifying a shape of the character projection pattern as a shape of one of a plurality of reference patterns by comparing the information on the character projection pattern with a plurality of pieces of information on the reference patterns; preparing writing data based on information on the identified shape of the character projection pattern; generating a charged particle beam based on the writing data; and exposing a resist film formed on a semiconductor substrate by the charged particle beam.
	description	This application claims priority to European Patent Application No. 05022818.8, filed Oct. 19, 2005, which is herein incorporated by reference. 1. Field of the Invention Embodiments of the present invention relate to a charged particle beam apparatus and, more particularly, to an arrangement and a method to compensate for variations in the tip location, especially tip vibrations of an emitter tip. More specifically, embodiments described herein relate to a charged particle beam apparatus as well as to a method of compensating variations in an emitter location of a charged particle beam apparatus. 2. Description of the Related Art Charged particle beam apparatuses are used in a plurality of industrial fields, including, but not limited to, high resolution imaging and processing of samples, inspection of semiconductor devices during manufacturing, exposure systems for lithography, detecting devices and testing systems. There is a high demand for structuring, testing and inspecting specimens within the micrometer and nanometer scale. Micrometer and nanometer scale process control, inspection, or structuring is often done with charged particle beams, (e.g., electron beams). Charged particle beams offer superior spatial resolution compared to, for example, photon beams due to their short wavelengths. Although the prior art and embodiments of the present invention will be described in the following with reference to electrons, electron beams, electron emitters, or electron microscopes, those skilled in the art will understand that the explanations are also true for other charged particles, such as ions, ion beams, ion emitters, etc. The first step in the process of creating images in any electron microscope is the production of an electron beam. The electron beam is generated in a device often called an electron gun. Three major types of electron guns are used in electron microscopes: tungsten-hairpin filament guns, lanthanum-hexaboride (LaB6) guns, and field-emission guns. Field-emission guns offer several advantages over tungsten-hairpin filament guns or LaB6 guns. First, the brightness may be up to a thousand times greater than that of a tungsten gun. Second, the electrons are emitted from a point more narrow than that in the other sources. Thus, superior resolution is achieved by field-emission guns compared to tungsten or LaB6 guns. Furthermore, the energy spread of the emitted electrons is only about one-tenth that of the tungsten-hairpin gun and one-fifth that of the LaB6 gun. Finally, the field-emission gun has a very long life, up to a hundred times that of a tungsten gun. For these reasons, the field-emission gun is a good choice for a number of applications. The typical construction of a conventional electron emitter, such as a thermal field-emission (TFE) gun, a cold field-emission (CFE) gun, or a field-assisted photocathode, is shown in FIGS. 9a to 9c. In FIG. 9a, the emitter assembly is mounted on an insulating ceramic base 1, which is normally a ceramic socket. A hairpin wire (support) 3 is attached to two metal support pins 2. The hairpin wire 3, which is made typically out of tungsten, can also be used as a heater in cases where the emitter requires heat for normal operation, for cleaning, for processing or for other reasons. The emitter 4 is supported by a supporting member formed by the base, the support pins and the hairpin wire (filament). Typically, the bent tungsten wire 3 is attached to support pins 2 by spot welding. The rear end 2b of the support pins are used as connection terminals. A very finely curved sharp tungsten tip serves as the emitter tip (particle beam source) 4 and is attached to the bent tungsten wire 3. Typically, the emitter tip 4a is attached to the heating filament 3 by spot welding. However, the conventional field-emission gun shown in FIGS. 9a to 9c suffers, for example, from mechanical vibration of the emitter. Mechanical vibrations of the emitter tip significantly limit the achievable resolution. This applies to many corpuscular beam systems, but in particular to scanning particle beam systems. The problem of mechanical vibration will be explained with reference to FIGS. 9d and 9e. FIG. 9d shows a first vibrational mode of the conventional field-emission gun shown in FIGS. 9a to 9c. In this first vibrational mode, the emitter tip 4a undergoes a displacement in the x-direction. However, the emitter configuration is stiff in the x-direction so that such a displacement in x-direction corresponds to a higher order vibrational excitation which may even include torsion movements of the heating filament 3. Accordingly, such a high order vibrational mode has a very high eigenfrequency and is strongly damped. Therefore, this first vibrational mode has only a very small amplitude and, therefore, has not yet been observed in experiments. FIG. 9e shows a second vibrational mode of the conventional field-emission gun shown in FIGS. 9a to 9c. In this second vibrational mode, the emitter tip 4a undergoes a displacement in the y-direction. This displacement in the y-direction is caused by bending of the heating filament 3. While being stiff in the x-direction, the emitter configuration is not very stiff in the y-direction so that a bending movement of the heating filament 3 in the y-direction corresponds to a lower order vibrational mode. Typically, this second vibrational mode of the emitter has an eigenfrequency of about 2 kHz. Furthermore, the damping is not very strong so that the second vibrational mode has a considerable amplitude. In fact, this amplitude may be so large, (e.g., within the nanometer range) that it can be observed in an experiment. Consequently, the displacement of the emitter tip 4a in the y-direction limits the resolution of some electron microscopes, especially for hairpin sources with an emitter needle welded on top of the hairpin, which are used in many applications like scanning electron microscopes (SEMs), focused ion beams (FIBs), writing and modification tools. In particular, the second vibrational mode can be introduced by vibrations of the system or acoustic noise. The frequencies of these vibrations are in the kHz regime, and amplitudes of several nanometers can occur. The tip vibrations become resolution-limiting in particle beam system with particle beam sources of small (virtual) size. Examples are cold field emitters (CFEs) in electron-beam technology, which have a virtual sources size of about 3 nm. Ion beam technology sources with small effective diameters are also known. In the past it has been suggested to stabilize the emitter tip by adding an additional filament, that is a third wire, which may then be arranged, for example, in an angle of 90° to the filament shown in FIGS. 9a to 9e. Thereby, particularly the second vibrational mode is intended to be reduced. Such a device can increase the stability or stiffness of the arrangement to a certain degree. Nevertheless, when the tip is heated through the wire, an arrangement having more than two connections to the terminal positioned in one plane may introduce a drift due to deformation of the wires. Further, it is still difficult to guarantee a very high stability. For high resolution applications, with a resolution of 1 nanometer or below, stability of 1 nm or below would need to be guaranteed. One embodiment of the present invention provides a charged particle beam apparatus. The charged particle beam apparatus generally includes a charged particle beam source (composed of an emitter with an emitter tip and a supporting member configured to support the emitter), an emitter location measuring device configured to repeatedly measure the location of the emitter, and a deflector system configured to compensate for variations in the location of the emitter. Another embodiment of the present invention provides for a charged particle beam apparatus. The charged particle beam apparatus generally includes a charged particle beam source (composed of an emitter with an emitter tip and a supporting member configured to support the emitter), an emitter location measuring device configured to repeatedly measure the location of the emitter, and a stage positioning system adapted to compensate for variations in the location of the emitter. Yet another embodiment of the present invention is a method of compensating variations in an emitter location of a charged particle beam apparatus. The method generally includes measuring the emitter location of a charged particle beam emitter of the apparatus and compensating for variations in the emitter location. Embodiments of the present invention provide an emitter configuration with improved resolution due to compensation of variations in the location of the (virtual) emitter source. Further, variations in the relative position of the stage with respect to the charged particle beam column may be compensated for, and emission stability may be provided. Generally, references to vibrations of the emitter and/or the stage should be understood as an explanation of variations of the location of the emitter and/or stage. Nevertheless, vibrations are one kind of variation of the location of the emitter and/or the stage that may be particularly considerable. Other variations of the location can be introduced due to thermal drift, misalignment or insufficient positioning of movable components. Generally, the material for the hairpin wires and for the emitter tips, as described herein, is tungsten. However, independent of specific embodiments, the hairpin wire may also include tantalum or other suitable materials. Further, the emitter tip, which is often described as being a tungsten emitter tip, may also be made of other materials like carbon, diamond, tantalum and the like. The emitter tip may typically be a single crystal or amorphous. FIGS. 1a and 1b show side views of a first embodiment according to the present invention. FIG. 1a is a side view in the z-x-direction. FIG. 1b is a side view in the z-y-direction. An emitter configuration for an electron beam apparatus is shown. Emitter needle 4 with emitter tip and filament 3 may be supported by a ceramic base 1. To form the filament 3, the wire, which may include tungsten, tantalum or other suitable materials, may be bent into the loop, and the free ends of the loop may be attached to the first and second support pins 2 by any suitable means, such as spot welding. The support pins 2 may be made of metal and extend through the ceramic base 1 so that electrical contact can be made to the filament 3 via the support pins 2. An emitter tip 4a made of the tungsten crystal which has been formed into a very sharp tip may be spot welded to the filament. It can be seen that a base 1, which is typically a ceramic socket may hold a support wire 3 via support pins 2. The hairpin wire (support) 3 may be attached to two metal support pins 2. As the hairpin wire 3 may typically be made out of tungsten, tantalum or other suitable materials, it may also be used as a heater in cases where the emitter requires heat for normal operation, for cleaning or for other reasons. The rear ends 2b of the support pins 2 may be used as connection terminals for control of the emission source. A very finely curved sharp tungsten tip may serve as the emitter tip (particle beam source) 4a and may be attached to the bent tungsten wire 3. Typically, the emitter 4 is attached to the heating filament 3 by spot welding. Because of the mechanical design, this device may be sensitive to tip vibrations, in particular to the vibrational mode shown in FIG. 9e. Nevertheless, the design may also have benefits, such as easy and low-cost setup, insensitivity to temperature drift, good thermal isolation from the needle to the base, and the like. For example, a temperature drift may only cause a movement in the z-direction, which can be compensated by adjusting the imaging properties of the lens or the lenses in the column. In view of the above, in the first instance, it is not intended to provide a stable mechanical design, which may also provide the other benefits. In the first instance, it is rather proposed to measure the tip vibrations and compensate for the measured vibrations. Accordingly, the vibrations of the tip may be measured. The movement of the emission source resulting from the vibrations may then be compensated by compensating means arranged in the charged particle beam path. These compensating means may be arranged between the source and the specimen. Such compensating means, which may, for example, be deflectors in single stage, double stage or even higher stage arrangements, may be adapted to change the beam path such that it seems that the emitter location would move, when seen from the specimen side of the charged particle optics. The compensation means, for example, in the form of a deflector system, will be described in more detail below. The embodiment of FIGS. 1a and 1b shows an example of a contact-less measurement of the tip vibrations. Generally, without being limiting to this embodiment, contact-less measurement principles for measuring the tip vibrations are typically used. A light source 105, which may be a laser, may emit a light beam 101. The light beam 101 may be shaped to be a collimated beam. The light beam 101 may hit parts of the emitter needle and/or the emitter tip 4a. Alternatively or additionally, according to other embodiments (not shown), the light beam may also hit parts of the filament 3. Thereby, parts of the light beam may be blocked by the emitter. The rest of the emitted light may be detected with detector 106. The laser and the detector may provide an emitter location measuring device. Detector 106 may be a segmented array with, for example, two segments 106A and 106B. The “shadow” of the emitter which is projected onto the detector may result in a difference of the signals from segment 106A and 106B depending on variation of the tip location. Thus, a vibration of the tip in the y-direction can be determined based on the intensities measured by the segments of the detector. Generally, it may be preferred to use a laser beam as the light beam. The short bandwidth may improve optical imaging of the light beam and therefore, may simplify the measurement of, for example, the signal difference between segments 106A and 106B. Further, some measuring arrangements, which may be applied, require the coherence of the laser to conduct the measurement. One example may be an interferometer that may also be used for measuring the amount and the frequency of the tip vibrations. FIGS. 2a and 2b show a further embodiment, which is fairly similar to the embodiment shown with respect to FIGS. 1a and 1b. FIG. 1a is a side view in the z-x-direction. FIG. 1b is a side view in the z-y-direction. However, within the embodiment of FIGS. 2a and 2b, the light beam 201 is a focused light beam. The focus of the light beam is at the position or close to the position of the emitter. On one hand, depending on the momentary position of the emitter with regard to a vibrational cycle, the light beam may be blocked to a larger extent. On the other hand, more intensity may pass the light beam if the emitter swings away from the focused light beam. Thus, the signal intensity difference between segments 106A and 106B may be increased by focusing the light beam. If the emitter needle is positioned at the position of the focus, the light beam might be blocked for both segments 106A and 106B of detector 106. This may result in reduced sensitivity for emitter positions with entirely blocked light beam. Thus, the focus might be positioned, for example, about 1 to about 5 mm before or behind the location of the needle in the x-direction. By adjusting the distance of the focus from the measuring position (needle or wire), the size of the shadow and the differences in intensity may be adjusted. If the emitter tip were imaged onto a detector array to, thereby, measure the vibration of the tip, the resolution of the measurement may be limited to be within the order of the wavelength of the light beam. Using UV light might thereby increase the resolution. However, a measurement in the nanometer range may not be possible by merely imaging the emitter tip and following the image of the tip. Therefore, signals other than the image on a camera should be used. One example to measure the vibration of the emitter tip within the nanometer range and in a range up to several 100 kHz is the measurement of the intensity on different segments, as described above with respect to segments 106A and 106B. Further, reflected light may be used as will be described with respect to another embodiment below. Generally, the intensity distribution of reflected light or of light passing by an obstacle is highly sensitive to the distance of the obstacle from, for instance, the entrance of a fiber optic. For example, if in one multi-fiber a first half of the fibers are used to provide laser light to an obstacle (e.g., the emitter tip) and the rest of the fibers are used to collect the reflected light, a vibrational detector with a resolution in the nanometer range and a frequency response in the several 100 kHz range may be realized. Alternatively for transmitted light, two multi-fibers may be used to provide a light curtain. Thereby, a plurality of emitting fibers may be provided on one side of the emitter needle, and a plurality of receiving fibers may be provided on the other side of the emitter needle. In between, the emitter and/or the filament as an obstacle may block the light of some fibers. The light of other fibers may not be blocked. Thus, the summed up intensity may be used as a measure of how far the emitter reaches into the light curtain. The above measurements and especially combinations thereof may allow for vibrational detectors with a resolution in the range of Angstroms and a frequency response of up to several 100 kHz. These effects described in detail with regard to multi-fiber optics may also be utilized with other optical systems. Generally, the intensity of the transmitted and/or reflected light may be used as an indicator of the emitter needle/tip location in the light beam path. Other effects, like the Doppler Effect, may also be used or combined with the different kind of measurements described above. For some embodiments (not shown), an emitter location measuring device in the form of an interferometer may be used in order to measure the vibration of the emitter tip. Thereby, a mirror may be positioned along the direction of the vibration to be measured. For some embodiments, the mirror may either be attached to the emitter needle or to the hairpin wire. Alternatively, a flat within the emitter needle that acts as a mirror may be provided. An interferometer using, for example, a He—Ne laser may then be capable of measuring the vibrations of, for example, the second vibrational mode with a resolution of about 0.1 nm at a frequency of about 500 kHz. With respect to the above-described embodiment, which utilizes an interferometer, a second laser beam might be directed to the housing of the gun (i.e., the housing of the emitter) in an effort to provide a reference of the measured emitter location variations relative to the gun housing. Thereby, particular drifts of the emitter tip and/or the emitter configuration including the ceramic base and the filament may be measured. These drifts can, thereby, be determined relative to the gun housing, in which the emitter configuration is positioned. According to another embodiment (not shown), an interferometer system can be provided including two interferometer axes. One axis may be oriented along a first direction (e.g., y-direction) and one axis along a second direction (e.g., x-direction), which is essentially perpendicular to the first direction. An exemplary arrangement describing a measurement with reflected light is shown in FIG. 3. The light beam 301, which may either be focused or collimated and which may be emitted by laser 105, may be guided onto the emitter or the hairpin. Upon vibration of the emitter the light intensity and light direction, which is reflected to detector 106, may change. Detector 106 may be a segmented array with, for example, two segments. If vibrations occur, the light guided onto the detector may result in a difference of the signals from the individual segments. Thus, a vibration of the tip in the x- and/or y-direction may be determined based on the intensities measured by the segments of the detector. The position of the emitter or the vibrational amplitude and frequency, respectively, may be measured. A corresponding signal may then be output to signal output 209. In an effort to improve the reflection properties of the hairpin or the needle or to adapt the reflection (to provide more accurate measurement results), a flat, which acts as a mirror, may be provided. The flat may either be formed in the needle or the hairpin, or it may be attached to the needle or hairpin. In the above-mentioned embodiments, either the hairpin or the source needle may be used as a measurement point. Generally, the movement of the tip end is to be compensated for. More precisely, a variation of the location of the virtual point of emission of the emitter tip should be corrected. This might be better understood with reference to FIG. 11. FIG. 11 shows the tip 4a of an emitter 4. Beams 7 may be emitted from the emitter 4 as indicated by the rays shown. These rays may have a virtual emission source that is located at a distance d from the very tip end of emitter tip 4a. The virtual emission source may be located within the emitter tip 4a. In view of the above, a measurement point close to the emitter tip, at which the vibration is measured, may provide a result that better correlates to the movement of the emitter tip. In cases where the vibration of the hairpin or a bottom part of the needle is measured, the measurement results may be transformed to a movement of the tip end of the emitter needle. According to a further embodiment, other measuring devices may also be used. FIG. 4 shows a capacitive or inductive distance measuring device 406 as an emitter location measuring device. A signal indicative of the amplitude of the vibration and the frequency may be output by signal output 209. A further embodiment will now be described with respect to FIG. 5a. Therein, the measuring system which is shown in FIG. 3, including the laser 105 and the detector 106, may be used. An emitter configuration for an electron beam apparatus is shown. Emitter needle 4 with emitter tip and filament 3 may be supported by a ceramic base 1. To form the filament 3, the tungsten wire may be bent into the loop, and the free ends of the loop may be attached to the first and second support pins 2 by a suitable means, such as spot welding. Instead of tungsten, tantalum (e.g., for ion source) or other suitable materials may also be used. The support pins 2 may be made of metal and may extend through the ceramic base 1 so that electrical contact can be made to the filament 3 via the support pins 2. An emitter 4 made of the tungsten crystal which has been formed into a very sharp tip may be spot welded to the filament. A base 1, which is typically a ceramic socket, may hold a support wire 3 via support pins 2. The hairpin wire (support) 3 may be attached to two metal support pins 2. A third support pin 5 may be provided. Like the first and the second support pins 2, also this third support pin 5 may also be made of metal and may extend through the ceramic base 1. Alternatively, the third support pin may not extend through the base, but may be provided in the form of a stabilization point on the base. A stabilization element 6 may be attached to the third support pin 5 and to the filament 3 adjacent to the emitter tip. Typically, this stabilization element 6 may be formed of tungsten wire like the filament 3 and may be spot welded to the third support pin 5 and the filament 3. However, for some embodiments, stabilization element 6 may merely abut against the filament in a resilient manner. Thereby, vibrations of filament 3 may be reduced due to the spring forces of the stabilization element 6 acting on filament 3. Alternatively, the stabilization element 6 may be formed of other materials, or it may be integrally formed with the emitter tip. The emitter configuration shown in FIG. 5a may reduce vibrations of the emitter tip of emitter needle 4. In FIG. 5a, these reduced vibrations may be measured by the optical measuring system including laser 105 forming focused light beam 301. The reflected light may be detected similarly to the embodiments shown in FIG. 3 by detector 106. Stabilizing the emitter tip as described with respect to FIG. 5a may be applied to all embodiments described above. The stabilization may be used independently of the measurement arrangement for detecting the position of the emitter tip. Referring now to FIG. 5b, a system similar to FIGS. 2a and 2b is shown. Within the embodiment of FIG. 5b, the light beams 201x and 201y may be focused light beams. Two light beam sources 105x and 105y may be provided, and two segmented detectors 106x and 106y may be provided. Thereby, a variation in the location of the emitter tip along the x-direction (e.g., a vibrational mode as shown in FIG. 9d) and a variation of the emitter tip along the y-direction (e.g., a vibrational mode as shown in FIG. 9e) may be measured by two independent units. The variations in the x-direction and the y-direction may both be measured. In the embodiment of FIG. 5b, two measurement results may be output to signal outputs 209x and 209y. Alternatively, a combined x-y measurement may be conducted by an x-y measurement unit, and one signal, indicative of x-displacement and y-displacement, may be provided by a signal output. Independent of specific embodiments, a measurement in x-direction and y-direction to measure variations in the location of the emitter tip in x-direction and in y-direction may be used for all emitter location measuring devices and all charged particle beam apparatuses disclosed herein. Thereby, typically a second measuring assembly is included in the measuring device. Within FIG. 5b, the focus of the light beam is at the position or close to the position of the emitter. On the one hand, depending on the momentary position of the emitter with regard to a vibrational cycle, the light beam may be blocked to a larger extent. On the other hand, more intensity may pass the light beam if the emitter swings away from the focused light beam. Thus, the signal intensity difference between segments 106A and 106B may be increased by focusing the light beam. If the emitter needle is positioned at the position of the focus, the light beam might be blocked for both segments 106A and 106B of detector 106. This may result in reduced sensitivity for emitter positions with an entirely blocked light beam. Thus, the focus might be positioned, for example, about 1 to about 5 mm before or behind the location of the needle in the x-direction. By adjusting the distance of the focus from the measuring position (needle or wire), the size of the shadow and the differences in intensity may be adjusted. The above-described embodiments for measuring the source location, filament location or emitter location may result in an emitter location signal Slocation. A suitable calibration device may generate a correction signal Scorrection from this location signal. The correction signal may drive a deflection arrangement that is a correction deflector of a deflector system. The deflection arrangement may compensate for the movement of the tip/source with nanometer precision or below. The calibration device may take into account, for example, the distance of the emitter tip with respect to the position on which the location signal has been measured. Generally, for measurement principles based on segmented detectors, a detector array with a higher number of segments may be used. For example a 2×2, 4×4, or detectors with up to several thousand (e.g., 4096) segments may be used. Generally, all optical measurements described herein may be conducted by lens optics, whereby lenses are used for focusing, collimating, projecting or imaging a light beam, particularly a laser beam. Alternatively, or in combination, fiber optics may be used to guide the light beam to and from the emitter and/or the support wire. Thereby, it may especially be useful to utilize a multiple fiber to guide the light beams to and from the emitter. This will be explained in more detail below. Without being limited to one of the embodiments, the measuring arrangements described herein may be used for measuring the location of the tip and, as one example, therefore, the vibration of the tip. A general variation in the location may—besides vibrations—also be introduced due to misalignment or a drift of the emitter tip that can be introduced by temperature changes or the like. The deflection arrangements will now be described with respect to FIGS. 6 to 8. FIG. 6 shows a charged particle beam apparatus, which emits, for example, electrons. However, ions may also be emitted. The source arrangement 601 may include the emitter tip and the emitter location measuring device, as described above. The charged particle beam emitted by the source may be focused onto specimen 64 by objective lens 60. Scan system 62, which is exemplarily shown as a magnetic deflection system including deflection coils, may scan the charged particle beam over specimen 64. The emitter location signal or source location signal Slocation may be fed from signal output 209 to the calibration amplifier 603 generating the correction signal Scorrection from the emitter location signal. The correction signal may be provided to the correction deflectors 605. Within FIG. 6 these deflectors of the deflector system are shown as electrostatic deflectors. However, the correction deflectors of the deflector system may also be magnetic or combined magnetic-electrostatic. FIG. 6 shows a single stage correction deflector system, which may typically be capable of deflecting the beam in x-director and y-direction. Alternatively, a two-stage or the three-stage deflector system may be used as a correction deflection system. The correction deflectors in the system may deflect the charged particle beam according to the correction signal, which has been generated in an effort to compensate for the measured variations of the tip/source location. Thus, the vibrations of the emitter tip may be compensated by deflecting the beam with correction deflectors 605 of the deflector system. The deflector system may include electrostatic, magnetic or combined magnetic-electrostatic deflectors. It may be a single-stage, double-stage or even higher order stage system. Further, other compensation means and/or other means for deflecting the charged particle beam with respect to the specimen and, thus, compensating variations in the location of the virtual emission source may be applied. As one example, the sample may be retained on a piezo-table adapted to precisely move the sample in the x-direction and y-direction. Thereby, the variations in the relative position of the charged particle beam and the sample may also be compensated for. As another example, the deflection for compensating variations of the emitter location may also be added to the scan deflector system. Thus, the scan unit may act as a scanning unit and as a deflector system for compensation of variations of the emitter location. FIG. 6 shows the charged particle optics with a single lens. Nevertheless, more than one lens may be used in the charged particle beam column without departing from the scope of the present invention. For example, a condenser lens and an objective lens may be provided. The same applies to the other charged particle optical columns described in the present application. FIG. 7 shows a further embodiment of the charged particle column. As compared to FIG. 6, a two-stage correction deflection system 705 with magnetic deflectors may be provided. The scan deflection system 62 may be positioned to be an in-lens deflection system in order to be able to provide a reduced focal length of the objective lens. A further embodiment is shown in FIG. 8. In a high-resolution system, both the source stability and the sample stability are issues. Therefore, in addition to the above-mentioned embodiments, the sample location or the stage location may be measured by stage location measuring system 801. The stage location measuring system 801 may be, for example, an interferometer. For such an interferometer, a laser beam may be directed onto the stage along the x-direction and along the y-direction. According to a further embodiment, the position of the stage may be optionally measured with respect to the charged particle optical system that is the column. As mentioned above, the stage location measuring system may include an interferometer for each of the x- and y-directions. In order to measure the position of the stage or vibrations of the stage with respect to the charged particle optical system, an interferometer with laser beam impinging on the charged particle beam column may also be applied for the x- and the y-direction. Typically, the reference laser beam for measuring the column position as a reference for the stage position is directed onto the objective lens. Thereby, the stage is measured with respect to the optical element, which usually defines the optical axis of the column. Referring now to FIG. 8, the corresponding sample location signals (x and y), which may be indicative of a misalignment or a vibration of the stage and/or the column, may be fed to a stage calibration amplifier 803 generating a correction signal. The correction signal may be provided to the correction deflectors 605. The correction signal originating from the stage may be applied to the correction deflectors independently from the correction signal originating from the source. Alternatively, the correction signals of the source/tip and the sample/stage may be combined into one correction signal. The combined correction signal may compensate for variations in the tip location and the sample location. The combined correction signal may then be used to control the correction deflectors 605. Other embodiments with further compensation mechanisms are explained with respect to FIG. 12. FIG. 12 shows a charged particle beam apparatus, which emits, for example, electrons. However, ions may also be emitted. The source arrangement 601 may include the emitter tip and the emitter location measuring device, as described above. The emitter location measuring device may either include one emitter location measuring assembly for measuring variations in the location of the emitter along one direction. This may generally be the more relevant vibrational mode. Alternatively, it includes two measuring assemblies for measuring variations in the emitter location along a first direction (e.g., y-direction) and a second direction (e.g., x-direction). Yet, the emitter location measuring device may include a measuring assembly capable of measuring both directions. The charged particle beam emitted by the source may be focused onto specimen 64 by objective lens 60. Scan system 62, which is exemplarily shown as a magnetic deflection system including deflection coils, may scan the charged particle beam over specimen 64. For the embodiments described herein, electrostatic scan deflectors or combined magnetic-electrostatic scan deflectors may also be provided in the scan system. The emitter location signal or source location signal Slocation may be fed from signal output 209 to the calibration amplifier 603 generating the correction signal Scorrection from the emitter location signal. The correction signal may be provided to the correction deflectors 605. Within FIG. 12, these deflectors of the deflector system are shown to be post-lens deflectors. The deflector system may be positioned between the objective lens and the specimen or stage. Thereby, a deflection for compensating variations of the electron beam may not have influence on the focusing properties of the column. The deflection system shown in FIG. 12 is a magnetic single-stage deflection system. The correction deflectors in the system may deflect the charged particle beam according to the correction signal, which has been generated in an effort to compensate for the measured variations of the tip/source location. Thus, the vibrations of the emitter tip may be compensated by deflecting the beam with correction deflectors 605 of a deflector system. According to another embodiment (not shown), an in-lens deflector system for compensation variations in the electron beam position may be provided. Thereby, the deflector system 605, which is shown in FIG. 12 as a post-lens system, may be moved up to be positioned within the lens, particularly within the active region of the lens. According to an even further embodiment (not shown), the correction deflection with the scanning deflection of scan system 62 may be superposed. In the event of a magnetic deflection scan system as shown in FIG. 12, the correction signal may either be added to the scan signal, or the magnetic deflectors of the scan system may be provided with additional windings in the respective coils. Thus, one coil may be provided with scan deflection windings and with correction deflection windings. In the event, the scan system is provided as an electrostatic system, the correction signal may be added to the deflection system. Returning now to FIG. 12, sample locations signals may be measured with the stage location measuring system 801. Stage location measuring system is typically an interferometer measuring the sample position in the x-y-direction and in the y-direction. If a reference for the sample location is used, a reference interferometrical beam may be directed to the objective lens of the column. Sample location signals (x and y), which may be indicative of a misalignment or a vibration of the stage and/or the column, may be fed to a stage calibration amplifier 803 generating a correction signal. The correction signal may be provided to the correction deflectors 605. Within FIG. 12, the emitter location calibration amplifier 603 and the stage location calibration amplifier 803 may be further connected to a stage 82. Stage 82 may include positioning systems 82x and 82y. The movements of position systems 82x and 82y may allow for positioning of specimen 64 in the x-y plane. The correction signals from the calibration amplifiers 603, 803 may be provided to the stage in an effort to compensate for variations of the emitter location and/or for variations of the sample location by movement of the stage. As explained above, a piezo-system in the stage may be included and, thereby, the sample may be moved as required for compensating the variations of the emitter location. Generally, a piezo table, which is capable of moving the specimen in an x-y plane, may compensate the variation of the relative position of the charged particle beam and the specimen with high precision (nanometer-range) and in the kHz regime. According to another embodiment, the compensation signals of the calibration amplifiers 603 and 803 may be divided into a (low frequency/constant) correction component for the stage and into a (higher frequency) correction component for the deflector system 605. If for example large corrections are compensated by the stage and the remaining smaller corrections are compensated by the deflector system, the field strength of the compensation deflectors may be reduced. Generally, low frequency or constant compensation signals, which can, for example, be necessary in view of a drift or the like, may be compensated for by stage movements. The deflector system may compensate with respect to compensation signals of all frequencies due to the higher bandwidth. However, a constant deflection with high field strength in the deflector system may complicate compensation with the deflector system 605. Therefore, this compensation may be swapped for other compensation means like the stage. To realize this divided compensation, a dividing unit for dividing the correction signal into a deflector system correction signal and a stage positioning correction signal may be included. When a divided compensation is utilized, a non-piezo, mechanical positioning system with a resolution in the μm-range may also be used as another alternative. Those skilled in the art will understand that similar embodiments may also be provided, without a sample location calibration amplifier being involved in the compensation of the emitter vibrations. Thus, a stage positioning for compensation of variations in the location of the emitter may also be used for embodiments described with respect to FIGS. 6 and 7. In the following, embodiments of methods will be described with respect to FIG. 10. Thereby, dashed lines indicate optional method steps. Within step 110 the location of the emitter and/or the hairpin support wire may be measured. The location may be measured as a function of time for the x-direction and/or for the y-direction. Typically, the second vibrational mode shown in FIG. 9e is more critical. Thus, measurement of the y-direction may be sufficient. The location x(t) and y(t) may vary as a function of time t due to a drift or due to vibrations of the system. In step 112, the location of the emitter may be transformed into a correction signal. Thereby, the position of the virtual source of emission with respect to the position of measuring the location y(t) (and/or x(t)) may be taken into account. The correction signal YC(t) (and/or XC(t)) may then be used to compensate for movements of the emitter tip within step 114. This may be accomplished by providing the correction signals to correction deflectors. Optionally, within step 115, the location of the sample or the stage, respectively, may be measured. The location x′(t)/y′(t) may also be used to provide a correction signal to a deflector system. As indicated by dashed line 112a, the correction signals may either be generated independently for compensation of vibrations of the emitter and the stage, or a combined correction signal may be generated. If independent correction signals are generated, the signals may then be combined before control of the correction deflectors. As a further option, one of the location signals or both of the location signals may be analyzed in step 117 before calculating the correction signals. Thereby, a drift may be separated from a vibration with a certain frequency. Further, if there is more than one vibrational mode at different frequencies, these vibrational modes may also be separated. Thereby, the correction signal may be calculated more precisely. For example, a drift measured at the hairpin wire may be converted to a correction signal without any magnification if the drift originates from a movement of the entire emitter source. A vibration may need to be converted with a magnification depending on the distance of the virtual emission source from the pivot point of the vibration and depending on the distance of the measurement point from the pivot point of the vibration. The same applies to stage location measurements. There may be movements or misalignment of the stage with respect to the charged particle beam column, which may indicate a magnification factor of 1. This means, if the stage is misaligned by 20 nm, the charged particle beam is also misaligned by 20 nm. However, if, for example, the movement of the stage with respect to the column originates from a vibration of the column, a vibrational amplitude of the column in the range of about 10 nm may result in a movement of the beam on the specimen in the range of about 15 nm. Thus, separating the measured variation of the location into different components may improve the transformation of the location signals to the correction signals. Independent of specific embodiments, the following features may be provided independently or combined. The supporting member for further supporting the emitter may include a base and a support wire. Thereby, typically, the support wire may be a bent tungsten or tantalum hairpin wire. However, also other suitable materials may also be used. Further, the supporting member may include a stabilization element. The emitter location measuring device may be a contact-less measuring device. Typically, it may include a light source, such as a laser, and a detector. Yet, the detector may include at least two segments. For example, an array with 2×2 arrays, a 64×64 array or other segmented detectors may also be used. Additionally or optionally, the emitter location measuring device may include multi-fiber optics. Further, the emitter location measuring device may include an interferometer. As described above, the charged particle beam apparatus may further include a calibration amplifier for generating a correction signal provided to the deflector system, wherein the emitter correction signal is based on an emitter location signal of the emitter location measuring device. According to yet other embodiments, the following features may be provided independently or combined. Methods may include the steps of generating an emitter location signal; transforming the emitter location signal to a first correction signal; and providing the first correction signal to a deflector system. Methods may additionally or alternatively include: generating a stage location signal; transforming the stage location signal to a second correction signal; and providing the second correction signal to a deflector system. According to yet another embodiment, the method may include generating an emitter location signal and a stage location signal; transforming the emitter location signal and the stage location signal to a first correction signal; and providing the first correction signal to a deflector system. Additionally, the transforming step may further include analyzing the emitter location signal and/or the stage location signal with respect to different frequencies included in the variations in locations of the emitter and/or the stage. While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.
	summary
056407017	description	DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to methods for treating various types of particulate materials, and especially soil, which are contaminated with soluble radioactive species. While this process will be described primarily for removal of radioactive material, such as uranium, radium, cesium, cobalt, strontium, americium, thorium, plutonium, cerium, rubidium, and mixtures thereof, and the like, it also encompasses removal of other hazardous species such as copper, lead, or mercury in soluble form. This method can also be used to treat sludge, sediments, scrap yard dust, and the like. As used herein, the term "soil" includes all forms of particulate matter to which contaminates may adhere, such as, for example, gravel, sands, clay, fines, sand, rock, humus, etc. As used herein, the phrase "desirable organic material" includes all forms of organic matter which provides nutrients to the soil to promote plant growth, such as, for example, humus, humic acid, etc. It is common for radioactive contamination to be present in a particular fraction or fractions of the soil in soluble form. For example, soluble cationic contaminants will exchange onto the negatively charged clay fraction of the soils. The soluble contamination is also likely to adsorb onto the humus fraction of the soil, and to be present in fine vegetation. Although the method of the invention may be applied to soil particles of any size and having any composition, the method of the invention ideally is applied to pretreated portions of the contaminated soil, or contaminated process streams (i.e., extraction solutions used in removing contaminants from contaminated soil) containing small to fine soil particles (say less than about 1000 micrometers, preferably less than about 100 micrometers), clay and silt particles, organic matter like humus, and fine vegetation including root hairs and the like. In a first embodiment of the invention, the material to be treated is excavated soil. Initially, the excavated soil is processed to remove large objects such as pieces of wood, vegetation, concrete, rocks and other debris, having diameters larger than about 150 mm (about 6 inches). Large objects may be removed by filtering the excavated soil through a sieve or a screen. These larger objects can be checked for contamination, and if necessary, washed with the contaminant extracting solution, rinsed with water, checked for residual contaminants, and returned to the site as a portion of the recovered soil. Alternatively, the large objects may be crushed and added to the smaller sized, contaminated soil. The soil then may be processed in a mechanical size separator, such as for instance a rotating drum or vibrating screen device, to sort and prewash the feed soil with a contaminant extracting solution. The intermediate to smaller soil particles and contaminated effluent can then be treated/separated in any number of ways. For example, the intermediate particles may be separated from the smaller particles and the fines using a screen, or sieve, or other size separation techniques. The intermediate pieces of soil then may be washed with the contaminant extracting solution, rinsed with water, checked for residual contaminants, and returned to the site as recovered soil. Alternatively, the intermediate to smaller soil particles and effluent can be processed in a countercurrent flow size separator such as a mineral jig, abraded in an attrition scrubber which dislodges mineral slime or fines from them, and then rinsed in a second concurrent flow size separator. Suitable soil pretreatment methods are described in U.S. Pat. Nos. 5,045,240, issued Sep. 3, 1991 in the name of Skriba et al., 5,128,068, issued Jul. 7, 1992 in the name of Lahoda et al., U.S. patent application Ser. No. 648,673, filed Jan. 31, 1991, in the name of Lahoda et al., and U.S. patent application Ser. No. 722,458, filed Jun. 27, 1991, in the name of Grant et al., the disclosures of which are incorporated herein in their entirety. Next, the soil cleansed by the pretreatment process (preferably containing intermediate to small particles) and the contaminated effluent are separated. The cleansed soil undergoes subsequent washing with clean extracting agent and/or water to remove as much of the contaminated extraction fluid as possible, and then may be checked again for contamination. The radioactive contaminants, smaller soil particles (say less than about 100 micrometers) and fines, clay and silt particles, fine vegetation, and the soluble components of the soil are generally carried off with the effluent, and will be treated using the novel methods of the invention. The soil (typically a slurry mixture as described above) is mixed with an aqueous extracting solution which will transfer the radioactive contaminants to the extracting solution, either as particles or as a solute. The solution used to wash the soil will be dependent upon the contamination to be removed. For soluble contaminants, the solution will contain an extracting (i.e., leaching) agent. Many suitable extracting agents are known and common extracting agents suitable for leaching radioactive compounds include, for example, potassium carbonate, potassium bicarbonate, sodium carbonate, sodium bicarbonate, sodium chloride, acetic acid, sodium hypochloride, ammonium carbonate, ammonium bicarbonate, and others. One preferred extracting solution of the invention comprises a mixture of potassium carbonate and sodium carbonate. Another preferred extracting solution comprises ammonium carbonate. Depending upon the pH of the extracting solution, suitable carbonate extracting agents exist in bicarbonate form. Accordingly, as used herein, the term "carbonate" includes bicarbonate forms of the extracting agents. Carbonates of sodium and potassium are preferred over ammonium when the introduction of an unnatural cation (i.e., a cation that is not native to the soil) like ammonium may not be permitted. Aqueous solutions of the preferred compositions effectively remove uranium and surprisingly, even radium, to environmentally acceptable levels. For example, radium levels of between 5 and 15 picocuries per gram of soil may be achieved, depending upon the depth of the soil. The extracting solution should have a pH and be added in an amount sufficient to solubilize, disperse, and/or mobilize at least about 10%, preferably at least about 20%, more preferably at least about 30%, even more preferably at least about 40%, and most preferably at least about 50% by weight, of said contaminate into solution. Accordingly, depending upon the properties and make-up of the soil to be treated, the extracting solution should have a pH greater than or equal to about 7.5, preferably greater than or equal to about 8, more preferably greater than or equal to about 8.5, even more preferably greater than or equal to about 9, and most preferably greater than or equal to about 9.5. The extracting solution also can have a pH greater than or equal to about 10. As indicated in FIG. 1, the pH of the extracting solution can be adjusted to achieve the desired amount of contaminant removal. For solutions of sodium and potassium carbonate, or ammonium carbonate, the concentration of the solution should be about 0.001M or greater, preferably between about 0.01 and 0.02M. Fine vegetation, and especially root hairs, adsorb unacceptable levels of contamination which is not readily solubilized, dispersed and/or mobilized by extracting solution. The methods of the invention require separating this contaminated fraction from the contaminated soil and effluent after treatment with the extracting solution. Separation may be accomplished using any method known in the art. In one preferred embodiment, the fine vegetation is floated and/or fluidized from the soil, and then gathered using any suitable means, such as, for example, a vibrating screen. Once the radioactive species are sufficiently solubilized or dispersed into solution, the pH of the extraction solution then is lowered by the introduction of an acid. The acid is added in an amount sufficient to lower the pH of the extracting solution, and preferably to remove substantially all organic material from the extracting solution. It has been found that by lowering the pH of the extracting solution to less than or equal to about 10, preferably less than or equal to about 9, more preferably less than or equal to about 8, and even more preferably less than or equal to about 7, organic matter in general, and humus in particular, are substantially removed from the extracting solution by precipitation and/or coagulation, without substantially precipitating the contaminant. For reasons explained above, it is essential that the pH of the extracting solution be reduced prior to separation of the extracting solution from the washed soil. It has been found that by using the methods of the invention less than 500 ppm of total organic carbon remains in the extracting solution, preferably less than 350, more preferably less than 250, even more preferably less than 150 ppm, and most preferably less than 100 ppm. Accordingly, the acid can be added in an amount to remove substantially all organic material from the extracting solution. Acceptable acids include one or more mineral acids selected from the group consisting of hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, perchloric acid, carbonic acid, and mixtures thereof. Hydrochloric acid is especially preferred. Suitable acid concentrations can be readily determined by one skilled in the art. Highly concentrated acids are preferred. In the next step of the invention, the soil is separated from the extracting solution using any suitable method known in the art. Preferably, in this step the soil is treated with a flocculent and/or a coagulant to precipitate or coagulate substantially all of the desirable organic material and the soil particles. Suitable flocculents and coagulants include for example, MAGNIFLOC 950N, supplied by American Cyanamid, of Wayne, N.J. Then the soil, including any precipitate and coagulant, are separated from the extracting solution using any appropriate means, such as, for example, filtration. The extracted, washed soil should be rinsed with clean water to remove substantially all residual traces of contaminant. For the soil remediation process to be cost effective, the solubilized, dispersed contaminant must be removed from the severely contaminated extracting solution to allow the extraction solution to be recycled. Accordingly, in the next step the contaminated extracting solution is cleaned, whereupon part or all of it is re-used. Where the contaminants include radioactive compounds or heavy metals, the severely contaminated solution can be passed through an ion exchange bed to remove the soluble metals. This type of procedure is well known. Ion exchange beads or the like, usually synthetic organic polymers or natural zeolite particles, having diameters over about 300 micrometers (30 U.S. Screen No. Sieve Size), well known to attract the contaminants present, would attract and remove most of the solubilized radioactive contaminants. As FIG. 3 shows, the presence of organics generated at a pH of 9.5 reduces the capacity of the ion exchange resin to remove radioactive contaminants from the extraction solution, while at pH 8 the organics are sufficiently insoluble so as to not adversely affect the ion exchange process. Depending upon the extraction solution and the form of contaminant, an anionic or cationic material may be used. Useful ion exchange materials include a strong acid cationic resin containing sulfonic functional groups with a styrene copolymer, and the like, for radium; and a strong base anionic resin containing quaternary ammonium functional groups with a styrene or styrene divinylbenzene copolymer, and the like, for uranium and thorium. In place of an ion exchange column, a precipitator could be used as an ion removal apparatus. For example, the solution could be mixed with ferric hydroxide, barium sulfate, or the like, to precipitate or co-precipitate radium or thorium, or with hydroxide to precipitate thorium or uranium, or with peroxide to precipitate uranium. Other ion exchange or precipitation materials could be used depending on the hazardous or radioactive material involved. For example, other adsorption media such as zeolites or treated clays may also be used to remove the contaminants. The ability to accomplish soil remediation using the methods of the invention is demonstrated in the following example. EXAMPLE Soil containing unacceptable levels of uranium and radium was washed using a 0.2M ammonium bicarbonate solution at a pH between 8.5 and 9.5. The excavated soil, which contained up to 40 weight percent clay, was contacted with the extractant for up to 1 minute. Up to 60 weight percent of the contamination was removed by the extractant. Root hairs, which were found to contain high levels of insoluble contamination (up to 400 ppm uranium and 20 pCi/g radium), were segregated from the soil/extracting solution mixture. The pH of the solution was then lowered to less than pH 8 using concentrated HCl. The clean soil was separated from the contaminated extractant by settling, filtration, and rinsing. The extractant solution was then successfully treated by ion exchange, and reused. The clean soil was capable of supporting plant growth. From the above, it can be seen that the invention provides a simple, yet highly effective method for treating soil contaminated with radioactive species. The method of the invention can be carried out on-site or off-site using any of the soil cleaning methods described herein. The invention having now been fully described, it should be understood that it may be embodied in other specific forms or variations without departing from its spirit or essential characteristics. Accordingly, the embodiments described above are to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.
063317133	summary	FIELD OF THE INVENTION This invention relates to an ion source assembly, in particular for use in an ion implanter. BACKGROUND OF THE INVENTION Ion implanters have been used for many years in the processing of semiconductor wafers. Typically, a beam of ions of a required species is produced and directed at a wafer or other semiconductor substrate, so that ions become implanted under the surface of the wafer. Implantation is typically used for producing regions in the semiconductor wafer of altered conductivity state, by implanting in the wafer ions of a required dopant. A number of arrangements for generating a source of ions in an ion implanter are known. Hot cathode sources, such as the so-called Freeman or Bernas sources, use a directly heated filament to generate a source of thermionic electrons. The cathode is held at a high negative potential relative to an anti-cathode (usually formed from the walls of an arc chamber) and an arc current flows through an admitted gas supply to generate a plasma. Alternatively, a microwave or rf source can be used. Here, a microwave or rf field excites free electrons which then ionise an admitted gas to again produce a source of ions for implanting. In one common arrangement, known as a triode structure, a suppression or extraction electrode is used to extract the ions from the ion source where they are formed. The extraction electrode is arranged adjacent to an extraction aperture formed in a face plate mounted upon the arc chamber of the ion source. The potential difference between the arc chamber and the extraction electrode defines the energy of the resultant ion beam. The triode structure also includes a ground electrode prevent electrons from being swept away and thus allows ion beam neutrality to be preserved. The face plate, suppression or extraction electrode and ground electrode are henceforth termed an extraction assembly. To permit acceleration of ions out of the ion source, the extraction electrode needs to be at a net negative potential with respect to the ion source itself. Thus, the ion source is typically electrically insulated from the extraction electrode by high voltage bushing formed from, for example, a ceramic based material A second, less common form of ion source assembly employs a tetrode structure. Here, instead of a dual purpose extraction/suppressor electrode such as is used in the triode structure described above, separate suppressor and extraction electrodes are employed. The suppressed electrode is electrically insulated from the suppressor electrode and is held at a net negative potential (for positively charged ions) with respect to it. Examples of tetrode structures are shown in U.S. Pat. No. 5,866,909 and WO99/23685. In both the triode and tetrode structures, the ion source, isolated from the extraction assembly, is mounted coaxially within a first end of an elongate, usually cylindrical vacuum chamber. The other, second end of the vacuum chamber is mounted, often non-removably, around an inlet into a mass analyser. The various parts of the ion source assembly (consisting of the ion source, extraction assembly, insulators and vacuum chamber) require frequent cleaning and servicing to prevent contamination of the resultant ion beam. For this reason, the ion source assembly must be dismantled. Such a process is difficult and time consuming. The trend to larger ion implanters has in turn caused larger ion source assemblies to evolve, which tend to be relatively heavy. To dismantle such assemblies can require two persons or even lifting equipment. Furthermore, the particular shape of some components of typical ion source assemblies can in any event make them difficult to remove without damage. For example, the extraction electrode in the tetrode structure shown in WO99/23685 is mounted upon the base of a `cup` shaped electrode support of relatively small diameter. The elongate ion source then extends into the cup such that a front face of the ion source is generally parallel with, and adjacent to, the base of the cup (and the extraction electrode in particular). Then, even when the ion source is removed, the extraction electrode can only be accessed via the narrow diameter of the cup. SUMMARY OF THE INVENTION It is an object of the present invention to address these and other problems with the prior art. More specifically, it is an object of the invention to provide an ion source assembly permitting easier access to the components thereof. According to the present invention, there is provided an ion source assembly for an ion implanter comprising a source sub assembly including an ion source for generating ions to be implanted; an extraction electrode for extracting ions from the ion source; and a first electrical insulator arranged to support the extraction electrode relative to the ion source and to electrically insulate the said extraction electrode from the ion source; and a chamber having a chamber wall with an inner and outer surface, and being arranged to receive ions extracted from the ion source, the chamber wall defining an exit aperture to permit egress of the said ions to the ion implanter; wherein the source sub assembly is movable relative to the chamber, the ion source assembly further comprising constraining apparatus arranged to connect the chamber wall with the source sub assembly such that the source sub assembly is constrained to move along a fixed locus of points relative to the chamber to allow access to the inner wall thereof, at least some of any loss in the potential energy of the source sub assembly during movement thereof being stored by the said constraining apparatus. The use of a constraining apparatus, such as for example a hinge, mounted between the first sub assembly and the chamber allows ready access to the internal components of the ion source assembly. In particular, to gain access to the inside of the chamber, the first sub assembly may simply be pulled away from the chamber, the constraining means acting to support the one part relative to the other part. This in turn avoids the problem of having to remove and carry away the bulky ion source, and then the extraction electrode, before access to the inside of the chamber could be gained. The risk of damage to the components of the source sub assembly is likewise reduced. Preferably, the source sub assembly is movable in use between a first position in which it is fixedly mounted upon the chamber walls and a second position in which it is movable relative to the chamber along the said fixed locus of points. For example, the constraining means may constrain the source sub assembly to move in a substantially horizontal plane, whereby, in the said first position, the weight of the source sub assembly is borne across the chamber, and in the said second position, the weight of the source sub assembly is substantially all borne by the said hinge means. Alternatively, for example, the constraining apparatus may constrain the sub assembly to move in both a horizontal and vertical plane. Then, it is preferable that the constraining apparatus should also include an energy storage device such as a spring or gas strut to store any loss in potential energy of the source sub assembly as it moves downwards in a vertical plane. This stored energy can be utilised when moving the source sub assembly back upwards in a vertical plane to assist the person moving it. Thus, when the source sub assembly is dismounted from the chamber, the user who wishes to clean the components of the ion source assembly does not need to support the weight of the source sub assembly. The source sub assembly, in the preferred embodiment, acts as a movable "door" hinged upon the chamber which is typically fixedly mounted to the ion implanter. Preferably, the ion source assembly further comprises extraction electrode support means arranged to support the said extract electrode relative to the said first electrical insulator. In that case, the ion source may be generally elongate and have a first end along the axis of elongation, the said first end preferably including an exit aperture permitting egress of ions, wherein the extraction electrode support means may also be elongate with a first end along the axis of elongation. The extraction electrode may in preference be mounted upon the said first end of the said extraction electrode support means, such that the axes of elongation of the extraction electrode support means and the ion source are generally collinear such that the extraction electrode is located generally parallel with and adjacent to the said exit aperture of the said first end of the ion source. The use of constraining means mounted between the source sub assembly and the chamber is particularly advantageous in this arrangement. The elongate nature of the ion source and the extraction electrode support means makes access to the extraction electrode from the ion source side (i.e. the side of the extraction electrode which faces the ion source when the assembly is assembled) difficult if the source sub assembly is simply disassembled. By allowing the whole source sub assembly to be moved relative to the chamber it is instead possible to access the extraction electrode from the chamber side, i.e. that side which faces into the chamber. In preferred embodiments of the present invention, the inner wall of the chamber may be lined with a liner. The use of a liner prevents the build up of ions on the walls of the chamber. As ions instead coat the liner, this can readily be removed and cleaned or replaced. Previously, the time and difficulty of accessing the inside walls of the chamber had prevented wide scale use of such liners. Preferably, the first end of the ion source constitutes a first electrode, and the said extraction electrode constitutes a second electrode, the assembly further comprising third and fourth electrodes mounted within the said chamber such that the second electrode is located between the first electrode and the third electrode, and the third electrode is located between the second electrode and the fourth electrode. The four electrodes constitute a tetrode structure which is particularly advantageous in "tuning" and focusing the resultant ion beam. The invention also extends to an ion implanter comprising: (i) an ion source assembly including a source sub assembly having an ion source for generating ions to be implanted, an extraction electrode for extracting ions from the ion source, and a first electrical insulator arranged to support the extraction electrode relative to the ion source and to electrically insulate the said extraction electrode from the ion source; the ion source assembly further including a chamber having a chamber wall and being arranged to receive ions extracted from the ion source, the chamber wall defining an exit aperture to permit egress of the said ions as an ion beam; and PA1 (ii) a substrate holder downstream of the ion source assembly, the ion beam being directed in use towards the said substrate holder, and the substrate holder being arranged to support at least one substrate to be implanted by the said ion beam; wherein the source sub assembly of the ion source assembly is movable relative to the chamber thereof, the ion source assembly further comprising constraining means arranged to connect the chamber wall with the source sub assembly such that the source sub assembly is constrained to move along a fixed locus of points relative to the chamber to allow access to the inner wall thereof. The ion implanter may further comprise mass analysing means arranged between the said ion source assembly and the said substrate holder, the chamber of the said ion source assembly being fixedly mountable relative to the mass analysing means.
	description	This application is a continuation application of application Ser. No. 14/434,209, filed Apr. 8, 2015, published as US 2015-0265238 A1 on Sep. 24, 2015, which is a national filing of PCT application Serial No. PCT/IB2013/059092, filed Oct. 3, 2013, published as WO 2014/057400 A1 on Apr. 17, 2014, which is incorporated herein by reference, and which claims the benefit of U.S. provisional application Ser. No. 61/712,877 filed Oct. 12, 2012, which is incorporated herein by reference. The present invention relates to a radiographic imaging apparatus comprising an X-ray source for projecting X-ray radiation into an examination region and a photon counting X-ray detector for receiving X-ray radiation after passing through said examination region and converting the received X-ray radiation into detector signals. Further, the present invention relates to a corresponding radiographic imaging method. A computed tomography (CT) scanner generally includes a rotating gantry rotatably mounted to a stationary gantry. The rotating gantry supports an X-ray tube and is configured to rotate around an examination region about a longitudinal axis. A detector array is located opposite the X-ray tube, across the examination region. The X-ray tube is configured to emit poly-energetic ionizing radiation that traverses the examination region (and a portion of an object or subject therein) and illuminates the detector array. The detector array includes a one or two dimensional array of detector pixels that detect the radiation and that generate signals indicative thereof. Each pixel is associated with a readout channel, which is used to convey a corresponding signal for further processing. A reconstructor reconstructs the processed signals, producing volumetric image data indicative of the examination region. For spectral CT, the detector pixels have included direct conversion detector pixels. Generally, a direct conversion pixel includes a direct conversion material (e.g., cadmium telluride (CdTe), cadmium zinc telluride (CZT) etc.) disposed between a cathode and an anode, with a voltage applied across the cathode and the anode. X-ray photons illuminate the cathode, transferring energy to electrons in the direct conversion material, which creates electron/hole pairs, with the electrons drifting towards the anode. The anode, in response, produces the electrical signal output by the detector array. An amplifier amplifies the electrical signal, and a pulse shaper processes the amplified electrical signal and produces a pulse having a peak amplitude or height that is indicative of the energy of the detected radiation. An energy discriminator compares the height of the pulse with one or more energy thresholds. For each threshold, a counter counts the number of times the pulse height crosses the threshold. An energy-binner bins the counts in energy-ranges, thereby energy-resolving the detected radiation. The reconstructor reconstructs the binned signals using a spectral reconstruction algorithm. Direct conversion material such as CdTe and CZT tends to produce a low frequency electrical current when irradiated with X-rays, which results in a baseline shift of the signals output by the detector pixels. Unfortunately, the baseline shift shifts the pulse output by the shaper, which can lead to erroneous binning of the detected radiation into incorrect energy bins as the discriminator thresholds remain static. There are two main components of this low frequency electrical current, namely dark current and persistent current. The dark current is a DC component that depends on the detector material and the bias voltage and usually does not change during an acquisition interval. This component can simply be corrected with a static bias compensation, which injects the same amount of current with the opposite sign to the input of the amplifier. The persistent current (PC) is caused by trapping (in the direct conversion material) of holes of the electron-hole pairs. Because of the positive potential of the trapped charges, electrons are injected into the bulk material and move to the anode instead of recombining with the holes. The resulting slowly varying current can be very strong and can exceed the photo current (the amount of charge directly generated by photons) by two orders of magnitude. This persistent current causes significant signal degradation and may generate unacceptable image artefacts if left uncorrected. Unfortunately, the persistent current dynamically changes and cannot simply be compensated with a static signal of the opposite sign like the dark current. It is an object of the present invention to provide a radiographic imaging apparatus and method that provide a simple and robust way of persistent current compensation. In a first aspect of the present invention a radiographic imaging apparatus is presented comprising an X-ray source for projecting X-ray radiation into an examination region and a photon counting X-ray detector for receiving X-ray radiation after passing through said examination region and converting the received X-ray radiation into detector signals, wherein said X-ray source comprises a cathode for emitting an electron beam, a rotary X-ray anode having a number of radial slits and a target layer provided on a surface of said rotary X-ray anode in between said radial slits for emitting X-ray radiation when hit by said electron beam, and a drive unit for rotating said X-ray anode,andwherein said photon counting X-ray detector comprises a direct conversion X-ray detection unit for receiving the X-ray radiation and outputting an electrical signal, a photon counting unit for generating, from said electrical signal, said detector signal representing the number of photons of the received X-ray radiation, and a persistent current sensing and correction unit for sensing a persistent output current in a blanking interval during which no X-ray radiation is emitted by said X-ray source and for using the sensed persistent output current to correct a detector signal generated by said photon counting unit in a subsequent measurement interval during which X-ray radiation is emitted by said X-ray source. In a further aspect of the present invention a radiographic imaging method is presented comprising projecting X-ray radiation into an examination region by use of an X-ray source comprising a cathode for emitting an electron beam, a rotary X-ray anode having a number of radial slits and a target layer provided on a surface of said rotary X-ray anode in between said radial slits for emitting X-ray radiation when hit by said electron beam, and a drive unit for rotating said X-ray anode, receiving X-ray radiation after passing through said examination region by use of a direct conversion X-ray detection unit, outputting an electrical signal from said direct conversion X-ray detection unit, converting the electrical signal into a detector signal representing the number of photons of the received X-ray radiation, sensing the persistent output current of the photon counting unit in a blanking interval during which no X-ray radiation is emitted by said X-ray source, and using the sensed persistent output current to correct a detector signal generated by said photon counting unit in a subsequent measurement interval during which X-ray radiation is emitted by said X-ray source. Preferred embodiments of the invention are defined in the dependent claims. It shall be understood that the claimed method has similar and/or identical preferred embodiments as the claimed system and as defined in the dependent claims. A very powerful correction scheme for compensation of persistent current is to periodically blank the X-ray beam during the acquisition, sense the device current during these intervals and use the obtained result for a DC correction of the successive measurement interval until the next blanking and PC sensing is performed. For periodically blanking the X-ray beam a slit anode is used. Some ultra high power X-ray tubes for CT imaging have such radial slits in the rotating anode to reduce the thermo mechanical stress of the anode. Whenever such a slit passes the electron beam, the output X-ray flux is temporarily reduced. Such a slit anode is e.g. described in U.S. Pat. No. 4,531,227. According to the present invention the X-ray blanking by use of a slit anode (also called slotted anode) is combined with the PC sensing intervals of a photon counting detector. Further, the persistent output current of the photon counting unit of the photon counting detector is sensed in a blanking interval during which no X-ray radiation is emitted. The sensed persistent output current is then used to correct a detector signal generated by said photon counting unit in a subsequent measurement interval during which X-ray radiation is emitted by said X-ray source. This provides for the desired simple and efficient way of persistent current compensation. The anode of the X-ray tube is optimized for this purpose. In an embodiment the width of the radial slits of the rotary anode is configured such that during a blanking interval the persistent output current can be completely sensed by said persistent current sensing and correction unit. Further, in an embodiment the radial slits of the rotary anode have a minimum slit width of FS+(R×Ω×T), wherein FS is the focal spot size on the anode, R is the radius of the focal track on the rotary anode, Ω is the angular speed of the rotary anode and T is the minimum time required for completely sensing the persistent output current by said persistent current sensing and correction unit. Herein, preferably, R is in the range from 5 cm to 35 cm, Ω is in the range from 2π×50 Hz to 2π×400 Hz, and T is in the range from 0.1 μsec to 100 μsec, and further said the angular width of a slit is in the range from 0.5 mm to 3 mm. In this way a practically useful implementation is provided. In a simply implementable embodiment said persistent current sensing and correction unit comprises an amplifier coupled between the output of said direct conversion X-ray detection unit and the input of said photon counting unit for amplifying said electrical signal, and a sample and hold unit for receiving said amplified electrical signal and generating, during the blanking interval, a compensation signal coupled to the output of said direct conversion X-ray detection unit for dynamically adjusting electrical signal to compensate the persistent output current. The sample and hold unit provides a PC compensation current to the input of the detection unit. During X-ray blanking, the sample and hold unit dynamically adjusts the output current to compensate the PC current. After the blanking interval, the compensation current is frozen and kept constant for the successive measurement interval. Thus, said sample and hold unit preferably comprises a switch for enabling a dynamic adjustment of the electrical signal during a blanking interval by use of the dynamically generated compensation signal and for keeping the compensation signal constant during a subsequent measurement interval. There are different embodiments for controlling said switch. In one embodiment the switch is advantageously controlled by a blanking signal to be synchronously with the blanking interval switched on and off. In another embodiment said switch is controlled by a blanking signal to be asynchronously with the measurement intervals of the photon counting X-ray detector and wherein a reference measurement is used to correct for X-ray flux variation caused by flux blanking. This embodiment does not require synchronization of the rotating tube anode and the measurement intervals, but requires reference measurements to compensate for flux variation caused by the X-ray blanking. In still another embodiment said switch is controlled by a blanking signal to be synchronously with the measurement intervals of the photon counting X-ray detector and between two successive measurement intervals. This embodiment has the advantage to keep the measurement intervals constant. This avoids the need to compensate varying measurement intervals. FIG. 1 shows a first embodiment of a proposed radiographic imaging apparatus 10. It comprises an X-ray source 20 for projecting X-ray radiation into an examination region 30 and a photon counting X-ray detector 40 for receiving X-ray radiation after passing through said examination region 30 and converting the received X-ray radiation into detector signals. In the examination region an object of examination, e.g. a patient, may be placed, e.g. lying on a patient table as generally known in the art. The X-ray source 20 comprises a cathode 21 for emitting an electron beam 22 and a rotary X-ray anode 23 having a number of radial slits 24 and a target layer 25 provided on a surface of said rotary X-ray anode 23 in between said radial slits 24 for emitting X-ray radiation 26 when hit by said electron beam 22. A drive unit 27, e.g. formed as an electric motor comprising a rotor and a stator body, is provided for rotating said X-ray anode 23. A top view on a rotary X-ray anode 23 having—in this exemplary embodiment—four radial slits 24 between the target material 25 is depicted in FIG. 2. A rotary X-ray anode having such slits is generally known in the art, e.g. from U.S. Pat. No. 4,531,227. The photon counting X-ray detector 40 comprises a direct conversion X-ray detection unit 50 for receiving the X-ray radiation and outputting an electrical signal, a photon counting unit 60 for generating, from said electrical signal, said detector signal representing the number of photons of the received X-ray radiation, and a persistent current sensing and correction unit 70 coupled between said X-ray detection unit 50 and said photon counting unit 60. Energy resolving detectors for X-ray and gamma radiation based on direct converter materials, as for example CdTe or CZT, can efficiently measure photon energies. The direct conversion X-ray detection unit 50 comprises a “converter element” 51, i.e. a block of semiconductor material, located between a cathode 52 and an array of anodes 53. A (high) voltage is applied to these electrodes by a readout unit 54. An incident photon X creates a number of electron/hole pairs. Thereafter, the electrons drift to the array of anode pixels 53 at the “bottom” side, while holes drift to the cathode 52. It is important to note, that already during the drift of the charge carriers a current is induced into the pixel anodes due to capacitive coupling. The currents in the pixel anodes are read out by the readout unit 54, which output electrical signals for subsequent evaluation. Such direct conversion X-ray detection unit is generally known in the art, e.g. from WO 2012/077023 A2. The persistent current sensing and correction unit 70 senses the persistent output current of the direct conversion X-ray detection unit 50 in a blanking interval during which no X-ray radiation is emitted by said X-ray source and uses the sensed persistent output current to correct a detector signal generated by said photon counting unit 60 in a subsequent measurement interval during which X-ray radiation is emitted by said X-ray source 20. The anode 23 of the X-ray tube 20 is preferably be optimized for this purpose. In an embodiment the anode 23 has about eight slits and a rotation frequency of about 200 Hz. The resulting blanking period is about 600 μsec which is close to a typical integration interval of a CT scanner. The slit width is preferably specified such that the X-ray flux is entirely blanked for a time period that matches the requirements of the PC sampling electronics, in particular the persistent current sensing and correction unit 70. In an embodiment an X-ray tube controller (not shown) should provide an electrical signal to indicate a blanking interval related to a slit 24 passing the electron beam 22. Preferably, the radial slits 24 of the rotary anode 23 have a minimum slit width of FS+(R×Ω×T), wherein FS is the focal spot size on the anode 23, R is the radius of the focal track on the rotary anode 23, Ω is the angular speed of the rotary anode 23 and T is the minimum time required for completely sensing the persistent output current by said persistent current sensing and correction unit 70. Typically, R is in the range from 5 cm to 35 cm, Ω is in the range from 2π×50 Hz to 2π×400 Hz, and T is in the range from 0.1 μsec to 100 μsec. The angular width of a slit is preferably in the range from 0.5 mm to 3 mm FIG. 3 shows an embodiment of a proposed persistent current sensing and correction unit 70. It comprises an amplifier 71 coupled between the output of said direct conversion X-ray detection unit 50 and the input of said photon counting unit 60 for amplifying said electrical signal, and a sample and hold unit 72 for receiving said amplified electrical signal and generating, during the blanking interval, a compensation signal coupled to the output of said direct conversion X-ray detection unit 50 for dynamically adjusting the electrical signal to compensate the persistent output current. Preferably, an additional pulse shaper 73 is provided at the output of the persistent current sensing and correction unit 70. In the embodiment shown in FIG. 3 the sample and hold unit 72 comprises a switch 74 for enabling a dynamic adjustment of the electrical signal during a blanking interval (e.g. controlled by an X-ray blanking signal S provided from a controller 76) by use of the dynamically generated compensation signal and for keeping the compensation signal constant during a subsequent measurement interval. For this purpose a buffer amplifier 75 is provided at the output of the switch 74. The two amplifiers in the sample-and-hold feedback path are mainly used to decouple the switch and hold-capacitor from the pre amplifier, and further, to avoid a discharge of the hold-capacitor by the compensation current. Thus, the sample and hold unit 72 thus provides a PC compensation current to the input of the photon counting unit 60. During X-ray blanking, the sample and hold unit 72 will dynamically adjust the output current to compensate the PC current (switch 74 is closed). After the blanking interval, the compensation current is frozen and kept constant for the successive measurement interval (switch 74 is open). In a preferred embodiment the blanking intervals are synchronously with the detector acquisition intervals (or with the anode rotation). In another preferred embodiment the blanking intervals may be asynchronously to the detector acquisition intervals. Often, CT scanners have a reference detector to monitor the output flux of the tube for each acquisition period. The acquired data are than used to correct for flux variation. Such a scheme may be used in this embodiment, which then automatically compensates for integral flux changes caused by the blanking intervals. Alternatively the anode rotation may be synchronized to the acquisition frequency or vice versa. FIG. 4 shows a second embodiment of a proposed radiographic imaging apparatus 100 which is implemented as a computed tomography (CT) scanner. The imaging apparatus 100 includes a stationary gantry 102 and a rotating gantry 104, which is rotatably supported by the stationary gantry 102. The rotating gantry 104 rotates around an examination region 106 about a z-axis. A radiation source 108, such as an X-ray tube, is supported by and rotates with the rotating gantry 104 around the examination region 106 about the z-axis. The source 108 emits radiation that traverses the examination region 106. An optional radiation controller 109 transitions a state of radiation emission between a first state in which radiation traverses the examination region 106 and a second state in which radiation does not traverse the examination region 106. This may include turning the source 108 “on”/“off,” inserting/removing a filter from the path of radiation, applying/removing a grid voltage to a switching grid of the source 108 to inhibit/allow electrons to flow from the cathode to the anode of the source 108, etc. A radiation sensitive detector array 110 subtends an angular arc across the examination region 106 opposite the radiation source 108. The detector array 110 detects radiation that traverses the examination region 106 and generates an electrical (e.g., a voltage or current) signal indicative thereof. The illustrated detector array 110 includes one or more rows of photon counting detector pixels 111 such as direct conversion detector pixels including a direct conversion crystal or material. For each of the detector pixels 111, an optional pre-amplifier 112 amplifies the electrical signal, and a pulse shaper 114 receives the electrical signal or amplified signal and generates a pulse (e.g., voltage or current) having a peak height or amplitude that is indicative of the energy level of the corresponding incident detected radiation. A persistent current estimator 116 (that corresponds to the persistent current sensing and correction unit 70) estimates, for each detector pixel 111, a value of the persistent current at the output of the corresponding shaper 114 and generates a persistent current compensation signal for each detector pixel 111. For a detector pixel 111, the persistent current sensing and correction unit 116 feeds or injects the compensation signal back to the input of the corresponding pre-amplifier 112, which substantially cancels the persistent current of that detector pixel 111 at the input of the pre-amplifier 112. This may substantially mitigate the baseline shift at the output of the shaper 114 of a detector pixel 111 due to the persistent current of that detector pixel 111. An energy-discriminator 118 energy-discriminates the pulse output by the shaper 114 for each detector pixel 111. The illustrated energy-discriminator 118 includes a set of comparators 1201, . . . , 120N (collectively referred to herein as comparators 120) and a corresponding set of predetermined energy thresholds (TH) 1221, . . . 122N (collectively referred to herein as energy thresholds 122), where N is an integer equal to or greater than one. Each of the comparators 120 compares the height of an incoming pulse with its respective one of the thresholds 122 and generates an output signal that indicates whether the peak height exceeded that threshold 122. A counter 124 (that corresponds to the photon counting unit 60) counts, for each of the comparators 120, when an individual threshold is exceeded by a peak of a pulse, for each of the plurality of pulses. An energy-binner 126 bins the counts into energy ranges based on a relationship between the threshold levels and the energy of incoming radiation, thereby energy-resolving the detected radiation. A reconstructor 128 reconstructs the energy-binned signals. The reconstructor 128 can employ a spectral and/or a non-spectral reconstruction algorithm to reconstruct the energy-binned signals. A subject support 130, such as a couch, supports an object or subject in the examination region 106. The subject support 130 can be used to vertically and/or horizontally position the subject or object relative to the imaging system 100 before, during, and/or after scanning. A general purpose computing system serves as an operator console 132 and includes an output device such as a display and an input device such as a keyboard, mouse, and/or the like. Software resident on the console 132 allows the operator to interact and/or operate the imaging system 100. Such interaction may include selecting an imaging protocol with or without grid switching, initiating scanning, etc. For further details of the function of the persistent current estimator and the way of compensating persistent current reference is made to the description of the first embodiment which basically holds for the second embodiment as well. FIG. 5 shows a flowchart of an embodiment of the proposed radiographic imaging method. Said method comprises the steps of projecting (S10) X-ray radiation into an examination region by use of an X-ray source comprising a cathode for emitting an electron beam, a rotary X-ray anode having a number of radial slits and a target layer provided on a surface of said rotary X-ray anode in between said radial slits for emitting X-ray radiation when hit by said electron beam, and a drive unit for rotating said X-ray anode, receiving (S12) X-ray radiation after passing through said examination region by use of a direct conversion X-ray detection unit, outputting (S14) an electrical signal from said direct conversion X-ray detection unit, converting (S16) the electrical signal into a detector signal representing the number of photons of the received X-ray radiation, sensing (S18) the persistent output current of the photon counting unit in a blanking interval during which no X-ray radiation is emitted by said X-ray source, and using (S20) the sensed persistent output current to correct a detector signal generated by said photon counting unit in a subsequent measurement interval during which X-ray radiation is emitted by said X-ray source. Further embodiments and variations of the proposed radiographic imaging method are possible corresponding to the embodiments and variations of the radiographic imaging device described above. In summary, the present invention provides a simple device and method for periodically X-ray flux pulsing for CT imaging to enable dynamic calibration of the persistent current in CZT photon counting detectors with ohmic contacts. While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. A single element or other unit may fulfill the functions of several items recited in the claims. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.
052271226	abstract	An advanced control room complex for a nuclear power plant, including a discrete indicator and alarm system (72) which is nuclear qualified for rapid response to changes in plant parameters and a component control system (64) which together provide a discrete monitoring and control capability at a panel (14-22, 26, 28) in the control room (10). A separate data processing system (70), which need not be nuclear qualified, provides integrated and overview information to the control room and to each panel, through CRTs (84) and a large, overhead integrated process status overview board (24). The discrete indicator and alarm system (72) and the data processing system (70) receive inputs from common plant sensors and validate the sensor outputs to arrive at a representative value of the parameter for use by the operator during both normal and accident conditions, thereby avoiding the need for him to assimilate data from each sensor individually. The integrated process status board (24) is at the apex of an information hierarchy that extends through four levels and provides access at each panel to the full display hierarchy. The control room panels are preferably of a modular construction, permitting the definition of inputs and outputs, the man machine interface, and the plant specific algorithms, to proceed in parallel with the fabrication of the panels, the installation of the equipment and the generic testing thereof.
	claims	1. A method for removing spent nuclear fuel from a fuel pool comprising the steps of:moving a cask below a handling mechanism that is at a fixed position below a penetration of the fuel pool using a transporter while a cover of the penetration is closed;raising the cask off of the transporter using the handling mechanism;securing the cask to the penetration while the cask is supported by the handling mechanism;moving the transporter away from the cask and the handling mechanism after the cask is raised off of the transporter by the handling mechanism;while the cask is sealed to the penetration, opening the cover of the penetration;inserting the spent fuel into the cask;after the spent fuel is inserted into the cask, unsealing the cask from the penetration;moving the transporter back below the cask and the handling mechanism and lowering the cask loaded with the spent fuel onto the transporter using the handling mechanism; andmoving the transporter with the cask loaded with the spent fuel away from the penetration and the handling mechanism. 2. The method according to claim 1, wherein the step of raising the cask from the transporter includes the steps of engaging upper trunnions of the cask with pivoting paddles of the handling mechanism. 3. The method according to claim 2, wherein the pivoting paddles have key-holes receiving the upper trunnions. 4. The method according to claim 1, wherein the handling mechanism comprises:a fixed position frame configured to permit the transporter to move thereunder while supporting the cask;a cask engagement tool movable in the vertical direction relative to the frame and configured to selectively move the spent nuclear fuel cask in the vertical direction relative to the frame when the cask is secured to the cask engagement tool to selectively raise and lower the cask onto and off of the transporter;a plurality of hydraulic cylinders extending between the frame and the cask engagement tool and configured to move together for raising and lowering the cask engagement tool relative to the frame; anda pair of paddles carried by the cask engagement tool and pivotably attached to the cask engagement tool for selectively engaging upper trunnions of the cask; andan actuator for selectively pivoting the pair of paddles into and out of engagement with the upper trunnions of the cask. 5. The method according to claim 4, wherein the paddles have keyholes for receiving the upper trunnions. 6. The method according to claim 4, wherein the frame is secured below a penetration of a fuel pool. 7. The method according to claim 4, wherein the frame is secured below the penetration of the fuel pool. 8. The method according to claim 4, wherein the cask engagement tool linearly moves in the vertical direction relative to the frame. 9. The method according to claim 4, wherein the linear actuators linearly raise and lower the cask engagement tool relative to the frame. 10. The method according to claim 4, wherein the handling mechanism is configured to engage only upper trunnions of the cask. 11. The method according to claim 1, wherein the transporter is self-powered vehicle. 12. The method according to claim 11, wherein the transporter is guided by rails near the penetration. 13. The method according to claim 11, wherein the self-powered vehicle comprisesa body;an upender secured to the body for holding the cask and moving the cask between vertical and horizontal orientations;a plurality of independently driven and independently steered duel wheel sets on each lateral side of the body;a plurality of drive motors for driving the plurality of duel wheel sets;a plurality of rotary actuators for steering the plurality of duel wheel sets; anda diesel-engine driven electric generator carried by the body for producing electric power to selectively move the upender structure, to selectively drive each of the duel wheel sets, and to selectively steer each of the duel wheel sets. 14. The vehicle according to claim 13, wherein each of the duel wheel sets includes a pair of coaxial wheels, one of the plurality of drive motors is located between the pair of wheels and coaxial with the pair of wheels, one of the plurality of rotary actuators is located above the drive motor and having a vertical axis of rotation for selectively rotating the pair of wheels, and the drive motor located between the pair of wheels. 15. The method according to claim 13, wherein the plurality of drive motors is a plurality of hydraulic motors. 16. The method according to claim 13, wherein the plurality of rotary actuators is a plurality of rack and pinion actuators. 17. The method according to claim 13, wherein the plurality of duel wheel sets includes four duel wheel sets on each lateral side of the body. 18. The method according to claim 1, further comprising the step of filling the cask with water while the cask is supported by the handling mechanism to equalize pressure with water within the fuel pool prior to the step of opening the penetration cover. 19. The method according to claim 1, after the step of moving the transporter away from the cask and the handling mechanism after the cask is raised off of the transporter by the handling mechanism, further comprising the step of engaging lower trunnions of the cask with a keyed structure of a seismic restraint to prevent swinging motion of the cask in a seismic event.
	summary
049903039	description	DETAILED DESCRIPTION The numeral 10 generally indicates a fuel element constructed according to the principles of the invention for use in a nuclear reactor. The fuel element includes a zirconium-tin alloy cladding tube 20, a boron-containing glass compound coating or sol-gel residue 30 on the inside of the zirconium-tin alloy cladding tube and pellets 40 of fissionable materials such as UO.sub.2. Lithium or sodium methoxide is dissolved in methanol, with a typical weight ratio of 1:20, by stirring in a closed container. Then a mixture of tetraethoxysilane and acidic aqueous solution (nitric acid (HNO.sub.3) in a 5 to 7, typically 6, weight percent concentration) is added to this lithium solution. The mole ratio of lithium or sodium methoxide to tetraethoxysilane is around 6:1. A reflux of the solution will be performed at a temperature range of 50-80.degree. C. (typically 70 .degree. C.) for a few hours, typically four, to achieve a partial hydrolysis of tetraethoxysilane. The mole ratio of water to tetraethoxysilane is 6:1. Now, tri-n-butylborate with is added slowly to the pre-hydrolyzed solution with constant stirring. (B.sup.10 makes up substantially all of the boron in the tri-n-butylborate.) Another reflux of the solution will be carried out at a temperature range of 50-80.degree. C. for a few more hours, typically four. Before the application of coating, the solution may be further diluted with 2 volume parts of methanol to approximately 1 volume part of solution, depending on the coating thickness requirement. The coating may be applied in any convenient manner; a multiple application may be needed for a thick coating. Other factors for controlling the coating thickness are the rates of application, viscosity of solution, and temperature. At the completion of coating, a heat-treatment of coated sample at 100-150.degree. C., (typically 125 .degree.C.) is performed in an oxidizing atmosphere to drive off volatiles. Then the completion of hydrolysis is accomplished at 200-250.degree. C. (typically 225.degree. C.) in a humid atmosphere. A subsequent heat treatment around 300 .degree. C is for burn-off of unreacted organics. After a final heat treatment at 400.degree. C., the preparation of B residue or coating on the Zircaloy tube is completed. The coating process as illustrated in FIG. 2 includes a process by which the liquid sol-gel is pumped upward into the cladding tube 10 while the tube is in the vertical position. The schematic arrangement of FIG. 2 shows that the hollow tube 10 is attached at its lower end by means of a hose and valve connector apparatus 50 having a valve 52 at the lower end of the tube 10 and a valve 54 adjacent its inlet port from a source of the liquid suspension. The connector 50 has a drain 56 between the two valves 52 and 54. A source of the liquid suspension schematically illustrated as a container of liquid 60 has a valve 62 connected by a conduit 64 to the connector 50 through its valve 54. A tube 68 provides a source of high pressure argon or other suitable gas pressurize the container 60 of the liquid suspension. the over-pressure of argon gas is used to pump the liquid up the tube 10 with the valves 62, 54 and 52 open. Air is exhausted from the tube 10 through an upper vent tube 66. The liquid suspension is held in the tube 10 by means of valve 52 approximately 1 minute. The liquid is then drained at a controlled rate manually controlling the valve 52. A rapid drain rate would result in the formation of a very thin coating, whereas the slower drain rate would produce coatings that would be thick and more irregular. The tube 10 is made of a zirconium-tin alloy which is commonly called Zircaloy-2 or Zircaloy-4. The compositions of Zircaloy-2 and Zircaloy-4 are shown in Table I, but it should be realized that each will contain some other impurities within tolerance limits known to those skilled in the art. Table I shows the alloying constituents and it should be remembered that the remainder is zirconium and that all ranges are given in percent by weight. Thus, it will be seen that the invention provides a nuclear fuel element having a burnable poison coating or residue in the form of a thin layer of boron-containing compound particles on the inside of the cladding tube in a manner which provides a matched thermal expansion coefficient between the cladding tube substrate and the coating to prevent spalling and which provides an adhesion promoting sintering phenomenon from the irradiated environment. The use of these improved elements eliminate the requirement of displacing fuel rods within the assembly lattice and therefore minimizes the fuel material that is displaced in the nuclear reactor core. TABLE I __________________________________________________________________________ ZIRCONIUM-TIN ALLOY (% BY WEIGHT) Zircaloy-2 Zircaloy-4 Range Typical Range Typical __________________________________________________________________________ Tin 1.20 to 1.70 1.55 1.20 to 1.70 1.53 Iron 0.07 to 0.20 0.14 0.18 to 0.24 0.22 Chromium 0.05 to 0.15 0.08 0.07 to 0.13 0.10 Nickel 0.03 to 0.08 0.06 -- -- Niobium (columbium) -- -- Oxygen A A A A Iron + chromium + nickel 0.18 to 0.38 0.28 -- 0.32 Iron + chromium -- 0.28 to 0.37 __________________________________________________________________________ The remainder is zirconium and impurities within tolerable amounts.
	description	This application claims priority from and the benefit of Korean Patent Application No. 10-2006-0048219, filed on May 29, 2006, which is hereby incorporated by reference for all purposes as if fully set forth herein. 1. Field of Invention The present invention relates to an irradiation device to test material using gamma rays radiated from a spent nuclear fuel assembly. In particular, in order to research a hardening process of material weakening due to radiation in atomic power facilities from gamma rays radiated from a spent nuclear fuel assembly, the present invention provides an irradiation device to test material, the device being capable of moving upward, downward and horizontally, thereby controlling a position of a spent nuclear fuel and a test material for a radiation test on the test material using gamma rays radiated from the spent nuclear fuel for accomplishing an evaluation of radiation effects. The present invention further provides an irradiation device for a material test using gamma rays radiated from a spent nuclear fuel assembly in which a scale is placed to discern a distance between the spent nuclear fuel assembly and a test material. 2. Discussion of the Background A spent nuclear fuel generally generated at a nuclear power or nuclear fuel laboratory generates various kinds of radiation such as a particles, β rays, γ rays, neutrons, etc. and the materials of facilities for handling and storing the spent nuclear fuel are to be irradiated by such radiation rays in a large amount. Therefore, various kinds of parts and devices constructed in the facilities for handling and storing the spent nuclear fuel are degenerated by being exposed to the radiation circumstance, and this is regarded as a main cause of a malfunction of the parts and devices used for handling the spent nuclear fuel or a decrease in the longevity thereof. Therefore, in order to operate the facilities for handling and storing the spent nuclear fuel safely, it is important to evaluate the effects caused by radiation of various kinds on nuclear power material. In order to do so, the experiments to identify a degeneration phenomenon of the materials exposed to radiation circumstance, need to consider effects caused by neutral particles, alpha particles and beta rays among the radiation generated from the spent nuclear fuel, which except for effects caused by gamma rays are so scarce, since experiments for identifying the degeneration phenomenon of the materials exposed to the radiation circumstance are performed under the gamma ray irradiation until now. To perform such experiments, the existing facilities for an irradiation test using gamma rays have mainly used 60Co sources and the gamma rays evaluation test of gamma rays on materials are partially performed using 137Cs sources. In the existing gamma ray irradiation facility, using 60Co sources and 137CS sources, where the gamma rays energies are at 1.17 MeV, 1.332 MeV and at 0.662 MeV respectively, cannot describe a various energy spectrum of gamma rays generated from a spent nuclear fuel and the effects thereof on material. Since such energy and flux-to-dose-rate of gamma rays generated from a spent nuclear fuel assembly have a various spectrum according to burn-up, cooling time, position and distance of nuclear fuel assembly, it is required to develop and make an irradiation device to describe the various circumstances of gamma ray irradiation radiated from a spent nuclear fuel. The present invention provides an irradiation device to test material capable of moving upward, downward and horizontally to accomplish an evaluation of radiation effects, thereby controlling a position of a spent nuclear fuel and a test material for a radiation test on the test material using gamma rays radiated from the spent nuclear fuel and further provides an irradiation device to test material using gamma rays radiated from a spent nuclear fuel assembly in which a scale is placed to discern a distance between the spent nuclear fuel assembly and the test material. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. The invention is described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure is thorough, and will fully convey the scope of the invention to those skilled in the art. Like reference numerals in the drawings denote like elements. The present invention provides an irradiation device to test material using gamma rays radiated from a spent nuclear fuel assembly which includes a support placed in the vertical direction; a vertical moving table which is capable of moving upward and downward connected with a position of the support; a moving device for moving said vertical moving table upward and downward; a horizontal moving table which is capable of moving horizontally placed on the vertical moving table; a horizontal moving bar which is capable of moving horizontally placed on the vertical moving table; and a driving device for driving the horizontal moving table and the horizontal moving bar horizontally. Desirably, the support comprises shaped steels, each having two wings and both wings separated from each other by a fixed space distance, a bottom plate placed horizontally under the shaped steels, a flat plate having a plate body placed in front of the shaped steels with a longitudinal direction, and a linear guide rail placed on each of the right and left side of the front of the flat plate. In this place, a reinforcement member slopes at a fixed angle on a position of a front-below side of the flat plate and on an end portion of one side of the bottom plate. And a guide having a flat plate body is formed on a front-top of the flat plate, the guide is connected with the flat plate by a plate body and a guide hole is pierced on the top of the guide through the flat plate body. Meanwhile, a support plate having a plate body is constructed on the top of the back side of the flat plate. In this place, the vertical moving table is composed of an upper plate having a plate body, a lower plate spaced apart from the upper plate by a fixed distance, the lower plate substantially the same length and shape as the upper plate and a vertical flat plate placed vertically on one end of the upper plate and a corresponding one end of the lower plate, respectively. And a reinforcement member slopes at a fixed angle on the bottom end of the vertical flat plate and another end of the lower plate. In addition, both sides of one end of the upper plate and the lower plate have L-shaped coupling parts respectively and a plurality of slider blocks are placed in the vertical direction to each of the coupling parts. And a coupling hole having a fixed diameter is pierced on a portion in the middle part of the upper plate and the lower plate respectively. Also, a plurality of taps for combining a locking member therewith are pierced on the upper plate and the lower plate. Meanwhile, a scale having a fixed length is placed on a position of the upper plate. In this place, the moving device consists of a moving handle to apply a turning force, a decelerator for reducing the turning force provided by the moving handle, a bevel gear to apply a torque increased according as the turning force is reduced by the decelerator, a ball screw having a round bar shape connected with the bevel gear and a ball screw nut placed on a position of the ball screw. Desirably, support units are placed respectively on a position of both ends of the ball screw. Meanwhile, the horizontal moving table consists of a moving plate formed to be a plate body, a ball screw having a ball screw nut connected to a lower side of the moving plate, a bevel gear connected to one of the ends of the ball screw and a hinge bracket connected to the bevel gear. In this place, support units are placed respectively on a portion of both ends of the ball screw. And a plurality of slider blocks are placed on both sides of the lower side of the moving plate and a linear guide rail for moving the moving plate is combined with the slide blocks. Desirably, a fixed part of a pointer in a position on the moving plate in the shape of a wedge is exposed to the outside. In addition, a shaft having a square section on the top of the hinge bracket is projected upward. Meanwhile, the horizontal moving bar consists of a moving piece in the shape of a square bar, a ball screw having a ball screw nut connected with one end of the moving piece, a bevel gear connected with one of the ends of the ball screw and a hinge bracket connected with the bevel gear. Desirably, a slider block is formed on the end of the moving piece, a slide bar is connected with the slider block by inserting therein and an end of the slide bar and the ball screw nut are connected by a damping spring. And support units are placed respectively on a portion of both end sides of the ball screw. In addition, brackets having a guide roller for guiding a movement of the moving piece are placed respectively on both sides of the moving piece. In this place, a scale is built on the upper side of the moving piece. And a shaft having a square section on the upper side of the hinge bracket is projected upward. Meanwhile the driving device consists of a long driving bar having a round bar shape and a driving handle placed on the top end of the driving bar. Desirably, a coupling groove having a square section is formed on the lower side end of the driving bar. In this place, a shield and a reservoir for holding an atomic power material is further included. Desirably, the reservoir is in the shape of a hexahedron with an open top which includes a housing having an atomic power material and shielding body therein and a lid placed on the open top of the housing. Alternatively, a gasket is interposed between the housing and the lid. In this place, the gasket is made of metal material. Alternatively, the gasket is made of synthetic resin material. In this place, a plurality of locking holes having a locking member are pierced in the edge of the lid and a plurality of locking holes for installing a locking member are pierced in a flange in the upper and lower edges of the housing. And the shielding body consists of an upper shielding body and a lower shielding body and a setting groove for inserting and installing an atomic power material into a position of one side of the lower shielding body. In addition, an I bolt is placed on a position of both upper sides of the upper shielding body. Examples according to the present invention are explained in detail hereinafter referring to the attached figures. FIG. 1 represents a front view of a support of an irradiation device to test material using gamma rays radiated from a spent nuclear fuel assembly of the present invention, FIG. 2 represents a plan view of the support of an irradiation device of FIG. 1, FIG. 3 represents a front view of a vertical moving table of an irradiation device to test material using gamma rays radiated from a spent nuclear fuel assembly of the present invention, FIG. 4 represents a plan view of the vertical moving table of FIG. 3, FIG. 5 represents a front view of a moving device for moving a vertical moving table of an irradiation device to test material using gamma rays radiated from a spent nuclear fuel assembly of the present invention, FIG. 6 represents a plan view of the moving device for moving a vertical moving table of FIG. 5, FIG. 7 represents a front view of a horizontal moving table of an irradiation device to test material using gamma rays radiated from a spent nuclear fuel assembly of the present invention, FIG. 8 represents a plan view of the horizontal moving table of FIG. 7, FIG. 9 represents a front view of a horizontal moving bar of an irradiation device to test material using gamma rays radiated from a spent nuclear fuel assembly of the present invention, FIG. 10 represents a plan view of the horizontal moving bar of FIG. 9, FIG. 11 represents a front view of a driving handle of an irradiation device to test material using gamma rays radiated from a spent nuclear fuel assembly of the present invention, FIG. 12 represents a plan view of the driving handle of FIG. 11. As shown in the figures, the irradiation device 1 to test material using gamma rays radiated from a spent nuclear fuel assembly of the present invention comprises a support 10, a vertical moving table 20, a moving device 30, a horizontal moving table 40, a horizontal moving bar 50 and a driving device 60. The support 10 (FIG. 1 and FIG. 2) comprises shaped steels 11 each having two wings and both wings separated from each other by a fixed space distance, a bottom plate 12 placed horizontally under each shaped steel 11, a flat plate 13 having a plate body placed in front of each of the shaped steels 11 with a longitudinal direction, a linear guide rail 14 placed on each right and left side of the front of the flat plate 13. In this place, the linear guide rail 14 is placed in the vertical direction to the flat plate 13 and placed on a position of right and left sides of the flat plate 13. Meanwhile, a reinforcement member 15 for supporting the flat plate 13 slopes at a fixed angle on a position of a front-below side of the flat plate 13 and on a position of an end portion of the bottom plate 12. And the front side of each shaped steel 11 is connected with the back side of the flat plate 13 and supports the flat plate 13. That is, the flat plate 13 is placed in the vertical direction and each shaped steel 11 is placed to be in contact with each side of the back side of the flat plate 13 having a long plate body, thereby reinforcing the flat plate 13. Meanwhile, a guide 18 having a flat plate body is formed on a front-top of the flat plate 13 and a lateral side of the guide 18 is connected with the front side of the flat plate 13 by a plate body 19, but the guide 18 and the flat plate 13 are spaced apart from each other by a fixed distance and a guide hole 18a is pierced on the top of the guide 18 through the flat plate body. Also, the guide hole 18a is pierced in the central part of the guide 18 and the guide hole 18a is connected with a bar 62 of the driving device 60 (FIG. 11) described later by inserting therein and has a spin-pair relations with each other (FIG. 23). In this place, it is preferable that guides 18 placed on a front-upper side of the flat plate 13 be placed on each side of the flat plate 13 symmetrically with respect to the center of the flat plate 13. Also, a support plate 17 having a plate body is constructed on a position of the back-upper side of the flat plate 13 in order for the moving device 30 to be placed. The vertical moving table 20 (FIG. 3 and FIG. 4) is composed of an upper plate 21 having a plate body, a lower plate 22 spaced apart from the upper plate 21 by a fixed distance the lower plate 22 substantially the same length and shape as the upper plate 21 corresponding thereto, a vertical flat plate 23 placed vertically on the both sides of one end of the upper plate and the lower plate 21, 22 respectively and a reinforcement member 24 sloped at a fixed angle on the bottom end of the vertical flat plate 23 and the other end of the lower plate 22. In this place, the reinforcement member 24 sloped at a fixed angle between the lower plate 22 and the vertical flat plate 23 not only supports the lower plate 22 but also reinforces the relations of the upper plate and the lower plate 21, 22 and the vertical flat plate 23. Meanwhile, both sides of the one ends of the upper plate and the lower plate 21, 22 have L-shaped coupling parts 25 respectively and slider blocks 26 for moving upward and downward when connected with the linear guide rails 14 which are placed on both right and left sides of the flat plate 13 of the support 10, the slider blocks 26 are placed in the vertical direction to each of the coupling parts 25 and are constructed on the upper and lower ends of each vertical flat plate 23. An example of the present invention teaches that there are four slide blocks 26 constructed on the upper and lower ends of each vertical flat plate 23 but the slide blocks 26 can be more or less than four. And a coupling hole 27 with a fixed diameter corresponding to a ball screw nut 35 of the moving device 30 (FIG. 5 and FIG. 6) as described later is pierced on a position of the one ends of the upper and the lower plates 21, 22 in order to be connected with the ball screw nut 35. In addition, a plurality of taps 28 for combining a locking member therewith are pierced on the upper plate and the lower plate 21, 22. In this place, a scale 49 (see FIG. 8 and FIG. 18) having a fixed length is placed on a position of the upper plate 21 of the vertical moving table 20. The moving device 30 for moving the vertical moving table 20 upward and downward consists of a moving handle 31, a decelerator 32 for reducing the turning force provided by the moving handle 31, a bevel gear 33 for a torque increased according as the turning force is reduced by the decelerator 32 to be applied, a ball screw 34 having a round bar shape connected with the bevel gear 33 and a ball screw nut 35 placed on a position of the ball screw 34. In this place, support units 36 to be locked by a locking member such as a bolt are placed respectively on both end sides of the ball screw 34. In case of spinning the moving handle 31 by the above-said constitution, a turning force of the moving handle 31 is delivered to a ball screw 34 through the decelerator 32 and the bevel gear 33 and the ball screw 34 is spun by the delivered turning force. In the case of spinning the moving handle 31 by such a constitution, a turning force of the moving handle 31 is delivered to the ball screw 34 through the decelerator 32 and the bevel gear 33 and the delivered turning force spins the ball screw 34. And a ball screw nut 35 can be placed on a position of the ball screw 34 and by the spinning of the ball screw 34 the ball screw nut 35 moves upward and downward. At this time, support units 36 placed respectively on both ends of the ball screw 34 are fixed by a locking member (non-illustrated). In this place, it is preferable that a separate handle be further equipped to the moving handle 31 for workers to chuck and spin the moving handle 31. The horizontal moving table 40 (FIG. 7 and FIG. 8) consists of a moving plate 41 formed to be a plate body, a ball screw 42 having a ball screw nut 43 connected to a low part side of the moving plate 41, a bevel gear 45 connected to one of the end sides of the ball screw 42 and a hinge bracket 46 connected to the bevel gear 45. In this place, support units 44 are locked and fixed by a locking member (non-illustrated) respectively on a position of both end sides of the ball screw 42 and the ball screw nut 43 moves horizontally on the ball screw 42 by the spinning of the ball screw 42. Meanwhile, as stated above, in order to move the moving plate 41 connected with the ball screw nut 43 by moving of the ball screw nut 43 caused by the spinning of the ball screw 42, a plurality of slider blocks 47 are placed on a position of each side of the low part side of the moving plate 41 and linear guide rails 48 for moving the moving plate 41 according to the spinning of the ball screw 42 are combined with the slide blocks 47 in order for the slide blocks 47 to slide thereon wherein the linear guide rails 48 are connected by the locking member (non-illustrated) respectively with a position in the longitudinal direction of each side of the upper side of the upper plate 21 of the vertical moving table 20. In this place, a fixed part of a pointer 41a in a position of the moving plate 41 in the shape of a wedge is exposed to the outside, and the scale 49 is placed in a longitudinal direction of a position corresponding to the pointer 41a wherein the scale 49 is placed on a position of the upper plate 21 of the vertical moving table 20. In the case of horizontally moving the moving plate 41 of the horizontal moving table 40 by the constitution as stated above, a pointer 41a placed on a position of the moving plate 41 indicates the graduations of the scale 49 placed on a position of the upper plate 21 of the vertical moving table 20, thereby measuring the horizontal moving distance of the moving plate 41. Meanwhile, a shaft 46a having a square section on the top of the hinge bracket 46 is projected upward wherein the shaft 46a is connected with the driving device 60 (FIG. 11) stated later and the shaft 46a spins. The horizontal moving bar 50 (FIG. 9) consists of a moving piece 51 in the shape of square bar, a ball screw 52 having a ball screw nut 53 connected with one end of the moving piece 51, the ball screw 52 placed in a horizontal direction, a bevel gear 55 connected with one end of the ball screw 52 and a hinge bracket 56 connected with the bevel gear 55. In this place, a damping spring 53a is placed between the end sides of the ball screw nut 53 of the ball screw 52 and the one end of the moving piece 51, thereby connecting the ball screw nut 53 and the moving piece 51. Meanwhile, a slider block 57 is formed on the one end of the moving piece 51, a slide bar 58 is connected with the slider block 57 by inserting therein and an end of the slide bar 58 and the ball screw nut 53 are connected by the damping spring 53a. And support units 54 are fixed by a locking member (non-illustrated) and placed respectively on a portion of both ends of the ball screw 52 wherein the ball screw 52 spins centering around each support unit 54, thereby making the ball screw nut 53 placed on a position of the ball screw 52 able to move horizontally. According to the above-said constitution, the ball screw nut 53 moves horizontally by the spinning of the ball screw 52, the ball screw nut 53 is inserted into the damping spring 53a connected with the end thereof, and the slide bar 58 is combined with the slider block 57 connected with the damping spring 53a, thereby moving a moving piece 51 horizontally. At this time, a bracket 51b having a guide roller 51a for guiding the moving piece 51 is constructed on a position of both sides of the moving piece 51 of the horizontal moving bar 50 and the bracket 51b is connected with an upper side of the lower plate 22 of the vertical moving table by a locking member (non-illustrated). In this place, a scale 59 is built on an upper side of the moving piece 51 wherein it is possible to identify and measure a distance between a spent nuclear fuel assembly and a vertical moving table 20 during gamma ray irradiation by the scale 59. Meanwhile, a shaft 56a having a square section on the upper side of the hinge bracket 56 is projected upward and is connected with a driving bar 64 of the driving device 60 (FIG. 11) as stated later. The driving device 60 (FIG. 11 and FIG. 12) consists of a long driving bar 62 having a round bar shape and a driving handle 61 placed on the top end of the driving bar 62. In this place, a coupling groove 63 having a square section is formed on the lower end of the driving bar 62 and is connected with the shafts 46a, 56a (see FIG. 7 and FIG. 9) having a square section projected upward on the upper side of the hinge brackets 46, 56 which are placed respectively on the horizontal moving table 40 and the horizontal moving bar 50, and in the case of spinning the driving handle 61 of the driving device 60, the hinge brackets 46, 56 of the horizontal moving table 40 and the horizontal moving bar 50 spin accordingly and a moving plate 41 of the horizontal moving table 40 and a moving piece 51 of the horizontal moving bar 50 move. Meanwhile, it is preferable that a separate handle be further equipped to the driving handle 61 for workers to chuck and spin the driving handle 61. An example of the present invention teaches that the coupling groove 63 formed on the lower end of the driving bar 62 of the driving device 60 has a square section but it can have triangle, hexagon or octagon section and it is preferable that the shafts 46a, 56a of each hinge brackets 46, 56 connected with the coupling groove 63 be formed to correspond to a section shape of the coupling groove 63. A combination process of an irradiation device 1 to test material using gamma rays radiated from a spent nuclear fuel assembly of the present invention is explained hereinafter referring to FIGS. 13-24. First of all, a combination process of the support 10 and the vertical moving table 20 of the irradiation device 1 to test material using gamma rays radiated from a spent nuclear fuel assembly of the present invention is explained referring to FIGS. 13-14. The vertical moving table 20 is constructed on the support 10 and the flat plate 13. That is, the slider blocks 26 placed in the vertical direction on the vertical flat plate 23 of the vertical moving table 20 are combined with the linear guide rails 14 placed in the vertical direction on each of the right and left sides of the flat plate 13 of the support 10. As stated above, combining the slide blocks 26 of the vertical moving table 20 with the linear guide rail 14 of the support 10 makes the vertical moving table 20 move on the guide rail 14 of the support 10. In this manner, a vertical moving table 20 is placed on the support 10 and then the support 10 and the moving device 30 for moving the vertical moving table 20 upward and downward are combined together. That is, as illustrated in FIGS. 15 and 16, the vertical moving table 20 is constructed on the support 10 and the decelerator 32 of the moving device 30 is laid on the support plate 17 placed on the upper side of the flat plate 13 of the support 10 (see FIGS. 13 and 14). At this time, the ball screw nut 35 of the ball screw 34 connected with the decelerator 32 by the bevel gear 33 in the vertical direction is fixed by combining with the coupling hole 27 pierced on a position of the end side of the upper plate 21 of the vertical moving table 20 and the support units 36 placed respectively on a position of both ends of the ball screw 34 are connected with a position of the upper and lower portions of the front side of the flat plate 13 of the support 10 by a locking member (non-illustrated). In this place, a decelerator 32 placed on the support plate 17 constructed on the upper side of the flat plate 13 of the support 10 is connected with the support plate 17 and fixed by a locking member. Meanwhile, a ball screw 34 connected with the bevel gear 33 is placed on the upper side of the flat plate 13 of the support 10 and is built between plate bodies 19 (see FIG. 1 and FIG. 2) connecting the guide 18 with the flat plate 13 at a fixed distance from each other. And then, a horizontal moving table 40 is combined with the vertical moving table 20. That is, referring to FIGS. 17 and 18, the linear guide rails 48 are fixed on the plurality of taps 28 (see FIG. 3 and FIG. 4) placed on a position of both the right and left sides of the upper plate 21 in the longitudinal direction by a locking member (non-illustrated). That is, the linear guide rails 48 are placed respectively on the taps 28 pierced on both right and left sides of the upper plate 21 in a longitudinal direction by using a locking member. And the slider blocks 47 placed respectively on the lower side of the moving plate 41 of the horizontal moving table 40 are combined with each linear guide rail 48 locked on the upper plate 21 to be movable. At this time, the end of the ball screw 42 connected with the moving plate 41 by the ball screw nut 43 (see FIG. 8) is connected with the upper side of the vertical moving table 20 by a hinge bracket 46. As stated above, the horizontal moving table 40 is placed on the upper plate 21 of the vertical moving table 20 and the scale 49 is placed on one side of the upper plate 21 of the vertical moving table 20 wherein the scale 49 is placed on a corresponding position to the pointer 41a placed on the moving plate 41. And then, the horizontal moving bar 50 is built between the upper and lower plates 21, 22 of the vertical moving table 20. That is, as illustrated in FIGS. 19 and 20, the horizontal moving bar 50 is built on the center part of the space between the upper plate 21 and the lower plate 22 of the vertical moving plate 20 and then the bracket 51b (see FIG. 9) comprising a guide roller 51a placed respectively on a position of both sides of the moving piece 51 of the horizontal moving bar 50 is fixed on the lower plate 22 by a locking member (non-illustrated). Also, a hinge bracket 56 connected with the end of the moving piece 51 by the ball screw 52 is connected with the lower plate 22 of the vertical moving table 20 and support units 54 placed on the ends of the ball screw 52 of the horizontal moving bar 50 are fixed on the upper side of the lower plate 22 by a locking member (non-illustrated). As stated above, placing the moving bar 50 between the upper plate 21 and the lower plate 22 of the vertical moving table 20 is illustrated in FIGS. 21 and 22. In this manner, the horizontal moving table 40 is placed on the upper plate 21 of the vertical moving table 20 and the horizontal moving bar 50 is placed between the upper plate 21 and the lower plate 22 of the vertical moving table 20, thereby horizontally moving the horizontal moving table 40 and the horizontal moving bar 50 centering around the vertical moving table 20. Meanwhile, the horizontal moving table 40 is placed on the upper plate 21 of the vertical moving table 20, the horizontal moving bar 50 is placed between the upper plate 21 and the lower plate 22 of the vertical moving table 20 and then the driving device 60 for driving the horizontal moving bar 50 is placed thereon, thereby finishing the combination procedure of the irradiation device 1 to test material using gamma rays radiated from a spent nuclear fuel assembly. In this place, as illustrated in FIGS. 23 and 24, the driving device 60 is combined with the guide hole 18a of the guide 18 placed on the upper side of the flat plate 13 of the support 10 by inserting therein and the coupling groove 63 having a square section is connected with the horizontal moving table 40. That is, the driving bar 62 having a fixed length in a round bar shape of the driving device 60 is inserted and fixed in the guide hole 18a of the guide 18 placed on the upper side of the flat plate 13 of the support 10 and the lower side of the driving bar 62 in which the coupling groove 63 having a square section is formed is combined with the square section shaft 46a of the hinge bracket 46 placed on the end side of the horizontal moving table 40. As stated above, the vertical moving table 20 is built on the support 10, the moving device 30 is built on the vertical moving table 20, the horizontal moving table 40 and the horizontal moving bar 50 are built on the vertical moving table 20 and the driving device 60 is built thereon, thereby finishing the combination procedure of an irradiation device 1 to test material using gamma rays radiated from a spent nuclear fuel assembly. Meanwhile, in order to experiment on changes in all kinds of atomic power materials to radioactive rays radiated from a spent nuclear fuel assembly using the irradiation device 1 to test material using gamma rays radiated from a spent nuclear fuel assembly of the present invention, a shield and a storage reservoir for holding an experimental material are needed. In this manner, in the irradiation device 1 to test material using gamma rays radiated from a spent nuclear fuel assembly, the reservoir 70 for holding an experimental material is, as illustrated in FIGS. 25, 26 and 27, in the shape of a hexahedron with an open top which consists of a housing 71 having an atomic power material 74 and a shielding body 75 therein, a lid 72 placed on the open top of the housing 71 and a gasket 73 placed between the housing 71 and the lid 72 for sealing them up. In this place, it is preferable that the gasket 73 be made of metal material and be in the shape of plate body for sealing up the housing 71 and the lid 72. An example of the present invention teaches that the gasket 73 is placed between the lid 72 and the housing 71 for preventing a fluid from inflowing during working under water but an O-ring made of synthetic resin material containing rubber material or a rubber ring can be placed between the lid 72 and the housing 71. In this place, a plurality of locking holes 72a having a locking member (non-illustrated) are pierced in the edge of the lid 72 and flanges 79 are placed respectively in the upper and lower edges of the housing 71 wherein a plurality of locking holes 79a for installing a locking member (non-illustrated) are pierced on a position of the flanges 79. Meanwhile, the shielding body 75 built in the housing 71 consists of an upper shielding body 76 and a lower shielding body 77 and a setting groove 77a for inserting and installing an atomic power material 74 into one side of the lower shielding body 77 is formed. In this place, an I bolt 76a for assembling and disassembling the shielding body is placed on a position of both upper sides of the upper shielding body. As stated above, in the irradiation device 1 to test material using gamma rays radiated from a spent nuclear fuel assembly, the reservoir 70 for holding an experimental material is placed on the moving plate 41 of the horizontal moving table 40 of the irradiation device 1 to test material using gamma rays radiated from a spent nuclear fuel assembly. We explain a driving procedure of the irradiation device 1 to test material using gamma rays radiated from a spent nuclear fuel assembly of the present invention referring to FIGS. 28 and 29 hereinafter. First of all, the irradiation device 1 to test material of the present invention is installed in a near position to a spent nuclear fuel assembly 3. At this time, the reservoir 70 for holding nuclear fuel materials is installed on a horizontal moving table 40 of the irradiation device 1 for material test using a gamma ray radiated from a spent nuclear fuel assembly 3. Also, by controlling the moving device 30 connected with the support 10 of the irradiation device 1 to test material using gamma rays radiated from the spent nuclear fuel assembly 3, the vertical moving table 20 installed on the support 10 to be movable upward and downward moves. That is, by controlling the moving handle 31 of the moving device 30 connected with the support 10, the ball screw 34 connected with the decelerator 32 of the moving handle 31 and the bevel gear 33 spins and the ball screw nut 35 connected with the upper plate 21 of the vertical moving table 20 and placed on a position of the ball screw 34 by the spinning of the ball screw 34 moves upward and downward, thereby moving the vertical moving table 20 upward and downward. At this time, the vertical moving table 20 is moved on the flat plate 13 of the support 10 upward and downward more easily by the slider blocks 26 placed on both sides of the vertical flat plate 23 of the vertical moving table 20 and the linear guide rails 14 combined with the slider blocks 26. As stated above, by moving the vertical moving table 20 upward and downward centering around the support 10 with the moving device 30 to place on a position of the spent nuclear power fuel assembly 3 in a longitudinal direction and by controlling the driving device 60, the horizontal moving table 40 moves horizontally to the spent nuclear fuel assembly 3. That is, the square section shaft 46a projected upward on the upper side of the hinge bracket 46 placed on the end of the horizontal moving table 40 is combined with the square section coupling groove 63 placed on the lower end of the driving bar 62 of the driving device 60 and then by controlling the driving handle 61 of the driving device 60, the ball screw 42 connected with the hinge bracket 46 by the bevel gear 45 spins and the ball screw nut 43 connected with the lower side of the moving plate 41 of the horizontal moving table 40 and placed on a position of the ball screw by the spinning of the ball screw 42 moves to move the horizontal moving table 40 horizontally centering around the vertical moving table 40. At this time, slider blocks 47 placed respectively on both lower sides of the moving plate 41 of the horizontal moving table 40 move along linear guide rails 48 placed respectively on a position of both sides of the vertical moving table 20, thereby moving the moving plate 41 of the horizontal moving table 40 horizontally more easily. In this place, it is possible to measure a moving distance of the horizontal moving table 40 by the pointer 41a placed on a position of the moving plate 41 of the horizontal moving table 40 and the scale 49 placed on a position corresponding to the pointer 41a and placed on the upper plate 21 of the vertical moving table 20. Meanwhile, the driving device 60 is controlled, thereby moving the horizontal moving bar 50 horizontally to the spent nuclear power fuel assembly 3. That is, the square section shaft 56a projected upward on the upper side of the hinge bracket 56 placed on the end side of the horizontal moving bar 50 is combined with the square section coupling groove 63 formed on the lower side of the driving bar 62 of the driving device 60 and then the ball screw 52 connected with the hinge bracket 56 by the bevel gear 55 by controlling the driving handle 61 of the driving device 60, the ball screw nut 53 moves horizontally by the spinning of the ball screw 52, the moving ball screw nut 53 is inserted into the damping spring 53a connected with the end side thereof and the slider bar 58 is combined with the slider block 57 connected with the damping spring 53a, thereby moving the moving piece 51. At this time, it is possible to measure a distance between the spent nuclear fuel assembly 3 and the vertical moving table 20 by the scale 59 placed on the upper side of the moving piece 51 of the horizontal moving bar 50. In this manner, by moving the vertical moving table 20 upward and downward to a position for irradiating gamma rays centering around the support 10 and moving the horizontal moving table 40 and the horizontal moving bar 50 horizontally, a moving distance of the horizontal moving table 40 and a distance between the vertical moving table 20 and the spent nuclear fuel assembly 3 are measured, it is possible to control the distance between the radiation materials and the spent nuclear fuel assembly 3 and make a research on the degeneration phenomenon of materials susceptible to the radiation and evaluate the radiation effects on the materials used at facilities and devices handling spent nuclear fuel under the real situation. We explained the preferable example of the present invention above, but the scope of the present invention is not limited to such a specific example and it is possible for those skilled in the art to properly change the present invention within a scope described in the claims. As stated above, the present invention having such a constitution teaches that an irradiation device 1 to test material to achieve a radiation effect evaluation is manufactured to be movable upward, downward and horizontally in order to study the hardening phenomenon of the materials susceptible to the radiation among the atomic power facilities using gamma rays radiated from a spent nuclear fuel assembly, thereby it is possible to adjust a position of the spent nuclear fuel used to test material using gamma rays radiated from the spent nuclear fuel and a test material, identify a distance between the spent nuclear fuel and the test material easily with a scale and evaluate the radiation effects on the materials used at facilities handling spent nuclear fuel under the same situation as they are really exposed. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.
	description	The present invention relates to a method and apparatus for flattening solid surfaces by gas cluster ion beam irradiation and is applicable, for example, to flattening of surfaces of semiconductors and other electronic device materials as well as to flattening of various device surfaces and pattern surfaces. Various gas phase reaction processes have been developed and put to practical use for surface flattening and the like of electronic devices. For example, a substrate surface flattening method described in patent literature 1 flattens substrate surfaces by irradiating them with monatomic ions of Ar (argon) gas or the like or molecular ions at a low irradiation angle to cause sputtering. Recently, a method for flattening solid surfaces using a gas cluster ion beam has been drawing attention because of reduced surface damage and capability to reduce surface roughness greatly. For example, patent literature 2 discloses a method for reducing surface roughness by irradiating solid surfaces with a gas cluster ion beam. In this method, gas cluster ions directed at a workpiece are broken by collisions with the workpiece, causing multi-body collisions between constituent atoms or molecules of the clusters and constituent atoms or molecules of the workpiece, consequently causing conspicuous motion parallel to a workpiece surface, and thus producing a cut in a direction parallel (hereinafter referred to as a lateral direction) to the workpiece surface. This phenomenon is known as lateral sputtering. The lateral motion of particles with respect to the workpiece surface enables ultra-precision flat grinding corresponding to the size of atoms. A gas cluster ion beam, whose ion energy per atom is lower than in ion etching, enables required ultra-precision grinding without damaging the workpiece surface. This indicates the advantage that solid surface flattening by means of a gas cluster ion beam causes less damage to workpiece surface than ion etching described in patent literature 1. In the flattening by means of a gas cluster ion beam, it is generally recognized that preferably the cluster ion beam is directed approximately perpendicular to the workpiece surface. This is to make full use of the effect of “surface flattening by means of lateral sputtering.” However, although patent literature 2 described above states that the gas cluster ion beam may be directed obliquely depending on surface conditions such as curves, it does not mention any effect of directing the gas cluster ion beam obliquely. Thus, according to patent literature 2, it follows that the most efficient way to flatten a solid surface is to direct the beam approximately perpendicularly to the surface. An example of solid surface flattening by means of a gas cluster ion beam is also disclosed in patent literature 3. Patent literature 3 does not state the effect of an angle between the gas cluster ion beam and solid surface on surface flattening, either. In view of the use of “lateral sputtering” effect, it appears that patent literature 3 shows data on vertical irradiation as in the case of patent literature 2 described earlier. Solid surface flattening by means of gas cluster ion beam irradiation is also reported by non-patent literature 1. Toyoda, et al. irradiated surfaces of materials such as Ge, SiC, and GaN with Ar cluster ions and showed that surface roughness is reduced by the irradiation. Again, the gas cluster ion beam was directed approximately perpendicularly to the surfaces. On the other hand, non-patent literature 2 describes changes in the roughness of a solid surface when the solid surface is irradiated with a gas cluster ion beam at various irradiation angles. Between vertical incidence on the surface at 90° and irradiation parallel to the surface at 0°, it shows that an etching rate, i.e., speed at which the surface is etched, is the largest at the time of vertical incidence and decreases with decreases in the irradiation angle. Regarding relationship between the surface roughness and irradiation angle, by conducting experiments using irradiation angles 90°, 75°, 60°, 45°, and 30°, it shows that the surface roughness increases with decreases in the irradiation angle. Irradiation angles below 30° were not checked experimentally maybe because it was considered meaningless. Integrated circuits and other electronic devices as well as optical devices used for optical communications often contain concavo-convex patterns produced by microfabrication on solid surfaces or surfaces of thin-film materials. However, there has been no report on the use of a gas cluster ion beam for flattening of lateral wall surfaces in concave or convex portions of the concavo-convex patterns. This is because it is considered to be difficult to direct a gas cluster ion beam approximately perpendicularly to lateral wall surfaces in concave or convex portions and impossible to flatten the lateral wall surfaces by the mechanism of lateral sputtering. Recently, it has been found that irradiation angles smaller than 30° reduce surface roughness greatly (non-patent literature 3). This utilizes effect of oblique irradiation different from the conventional flattening mechanism by means of lateral sputtering. Patent literature 1: Japanese Patent Application Laid Open No. H07-058089 Patent literature 2: Japanese Patent Application Laid Open No. H08-120470 Patent literature 3: Japanese Patent Application Laid Open No. H08-293483 Non-patent literature 1: Jpn. J. Appl. Phys. Vol. 41 (2002), pp. 4287-4290 Non-patent literature 2: Materials Science and Engineering R34 (2001), pp. 231-295 Non-patent literature 3: Jpn. J. Appl. Phys. Vol. 43, 10A (2004), pp. L1253-L1255 The flattening method by means of sputtering with Ar gas or the like disclosed in patent literature 1 flattens a substrate surface to some extent by grinding convex portions on the substrate surface preferentially, but it must keep irradiation energy below about 100 eV in order to prevent damage to the substrate surface. This has a problem in that ion current is reduced extremely, making it impossible to obtain a practical sputtering rate. Also, when flattening a composite material which is a combination of different materials, there is a limit to flattening because the etching rate varies with the type of material. Regarding the methods for surface flattening by means of “approximately perpendicular lateral sputtering” through irradiation of solid surfaces with a gas cluster ion beam, such as those described in patent literatures 2 and 3 and non-patent literatures 1 and 2, although they reduce surface roughness to some extent, they cannot meet the demand to further reduce surface roughness because they cannot completely remove crater-like deformation formed on the solid surfaces during collisions of cluster ions. When flattening a composite material which is a combination of different materials, again the problem is that there is a limit to flattening because the etching rate varies with the type of material. The method described in non-patent literature 3 which uses irradiation angles smaller than 30° with respect to solid surfaces does not pay attention to controlling the cluster size of the gas cluster ion beam, and it turned out that there was a limit to flattening when flattening a composite material which is a combination of different materials. An object of the present invention is to solve the above problems and provide a surface flattening method and apparatus which cause less damage to solid surfaces of composite materials or polycrystals which have different etching rates within the same surface and can reduce their surface roughness more than conventional methods can. According to the present invention, a method for flattening a surface of a solid which has different etching rates within the same surface by irradiating the surface of the solid with a gas cluster ion beam includes: a step of irradiating the surface of the solid with the gas cluster ion beam with an average cluster size of 50 or larger at an irradiation angle smaller than 30° between the surface of the solid and the gas cluster ion beam. According to the present invention, a solid surface flattening apparatus which flattens a surface of a solid sample through irradiation with a gas cluster ion beam includes: means for generating the gas cluster ion beam; cluster size sorting means for selecting a cluster size equal to or larger than 50 for the gas cluster ion beam; sample supporting means for supporting the solid sample in such a way as to be able to vary an incident angle of the gas cluster ion beam whose cluster size has been selected; and irradiation angle setting means capable of setting an irradiation angle between the surface of the solid sample and the gas cluster ion beam to less than 30°. The present invention can reduce surface roughness and surface damage more than conventional methods can. An embodiment of the present invention will be described below with reference to examples. To begin with, a basic configuration of a gas cluster ion beam flattening apparatus which implements a solid surface flattening method according to the present invention will be described below with reference to FIG. 1. A source gas is injected into a cluster generating chamber 11 through a nozzle 10 and gas molecules are condensed to generate clusters. The clusters are introduced as a cluster beam into an ionization chamber 13 through a skimmer 12. In the ionization chamber 13, neutral clusters are ionized by electron rays such as thermoelectrons emitted from an ionizer 14. The ionized cluster beam is accelerated by an accelerating electrode 15, focused by a magnetic focusing device 16, and introduced into a strong magnetic deflection type cluster size sorting mechanism 17 which uses a permanent magnet. Since cluster ions vary in a deflection angle depending on their size (number of atoms or molecules), it is possible to select a cluster ion beam of desired size by selecting cluster ions of a desired deflection angle. The cluster ion beam whose cluster size is sorted and controlled enters a sputtering chamber 18. A sample 20 is mounted on a sample support 19 of an irradiation angle setting mechanism 30 installed in the sputtering chamber 18 and the incident cluster ion beam set to a predetermined beam diameter through an aperture 21 is directed at a surface of the sample 20. The irradiation angle setting mechanism 30 is controlled by a controller 40 so that the sample surface will form a desired irradiation angle θp with the cluster ion beam. Incidentally, if the sample 20 to be flattened is an electrical insulator, the cluster ions may be neutralized by electrons in advance. The following experiments were conducted using, for example, Si/SiO2 multilayer laminate films as the composite material whose surface was flattened according to the present invention and using, for example, an Al2O3—TiC sintered bodies and polycrystalline silicon films as materials which have different etching rates within the same surface. An SF6 cluster ion beam was generated using a mixture of SF6 gas and He gas as a source gas, and SF6 cluster ions accelerated to 5 to 70 keV were directed at surfaces of samples 20 at various irradiation angles θp. An irradiation dose was 4×1015 ions/cm2. After the irradiation, the roughness of the sample surfaces was measured under an atomic force microscope (AFM). Measurement results are shown in Table A in FIG. 2A. As the samples 20, the following samples were used: samples A1-1 to A1-8 of an alternately laminated multilayer film (50 layers) consisting of silicon (Si) films (100 nm thick) and silicon dioxide (SiO2) films (100 nm thick) formed on a silicon substrate by sputtering, samples A2-1 to A2-7 of Al2O3—TiC sintered bodies, samples A3-1 to A3-7 of a polycrystalline silicon film (represented by poly-Si) obtained by forming an amorphous silicon film on a silicon substrate by sputtering and crystallizing it by heat annealing. To evaluate flattening of a material layer with different etching rates, a silicon substrate on which an Si/SiO2 multilayer film was formed was cleaved to reveal a cross section of the multilayer film and the cross section of the multilayer film was irradiated with a gas cluster ion beam. The average surface roughness (Ra) of the composite materials before the flattening process was 2.19 nm in the case of the Si/SiO2 multilayer film, and 3.78 nm in the case of the Al2O3—TiC sintered bodies. The average surface roughness (Ra) of the polycrystalline silicon film was 2.95 nm. Regarding the polycrystalline silicon film, to measure the degree of damage on the surfaces after the flattening process, a profile of S which had penetrated into a surface layer of polycrystalline silicon film sample A3-4 at an irradiation angle of 25° was evaluated by secondary ion mass spectrometry (SIMS). It was found that S had penetrated only about 10 nm from the surface. On the other hand, in polycrystalline silicon film samples A3-6 and A3-7 at an irradiation angle of 30° or above, penetration was observed to a depth of 40 to 50 nm from the surface. Samples B1-1 to B1-5 consisting of a Si/SiO2 multilayer film were irradiated with a gas cluster ion beam by varying accelerating voltage with the irradiation angle θp fixed at 10°. The other conditions were the same as experiment A above. Results are shown in Table B in FIG. 2B. Samples C1-1 to C1-12 of a Si/SiO2 multilayer film, samples C2-1 to C2-12 of Al2O3—TiC sintered bodies, and samples C3-1 to C3-12 of a polycrystalline silicon film were irradiated with a gas cluster ion beam by varying the average cluster size with the irradiation angle θp fixed at 10°. The other conditions were the same as experiment A above. Results are shown in Table C in FIG. 3. An Ar cluster ion beam was generated using Ar gas as a source gas. Ar cluster ion beam accelerated to 30 keV were directed at cross sections of samples D1-1 to D1-7 of a Si/SiO2 multilayer film at various irradiation angles θp. Results are shown in Table D in FIG. 4A. The irradiation dose was 1×1016 ions/cm2. After the irradiation, the roughness of the sample surfaces was measured under an atomic force microscope (AFM). The other conditions were the same as experiment A. Cross sections of samples E1-1 to E1-12 of a Si/SiO2 multilayer film were irradiated with an Ar cluster ion beam by varying the cluster size with the irradiation angle θp fixed at 10°. The other conditions were the same as experiment D. Results are shown in Table E in FIG. 4B. Cross sections of samples F1-1 to F1-6 of a Si/SiO2 multilayer films of different thicknesses were irradiated with a gas cluster ion beam by varying the irradiation angle θp. In so doing, the thicknesses of layer films were varied from 10 nm to 5 μm with the film thicknesses of Si and SiO2 kept equal. After the irradiation, the roughness of the sample surfaces was measured under an atomic force microscope (AFM). The other conditions were the same as experiment A. Results are shown FIG. 5. Incidentally, the average surface roughness (Ra) of the cross sections of the Si/SiO2 multilayer samples before the flattening process was in the range of 2 to 3 nm. Resist was applied to a silicon substrate on which a 200-nm thick silicon dioxide film had been formed by thermal oxidation, a line-and-space pattern was drawn using an electron beam exposure system, and a mask pattern was formed by development. Line width was 1 μm and space width was 4 μm. The silicon dioxide film and silicon substrate were etched using an ion milling system. Total etch depth of the silicon dioxide film and silicon substrate was 500 nm. After a concavo-convex pattern was formed in this way, lateral wall surfaces in concave portions of Si/SiO2 material were flattened and evaluated in the same manner as experiments A, B, and C by regarding the Si/SiO2 material, which is a combination of different types of materials, as a composite material. The surface roughness of the lateral walls in concave portions were measured and results were almost the same as examples A, B, and C. Incidentally, the average surface roughness (Ra) of the lateral wall surfaces before the flattening process was in 3.52 nm. Discussion As shown in Tables A, C, D, and E by separating by broken lines, it can be seen that the surface roughness of composite material and polycrystals can be reduced greatly when the irradiation angle θp of a gas cluster ion beam is below 30° and the cluster size is 50 or above. This effect was not anticipated conventionally. That is, the solid surface flattening method according to the present invention is characterized in that the irradiation angle of a gas cluster ion beam is below 30° and that the cluster size is 50 or above. The irradiation conditions for samples A1-1 to A1-5, A2-1 to A2-5, and A3-1 to A3-5 in Table A; samples B1-1 to B1-5 in Table B; samples C1-4 to C1-12, C2-4 to C2-12, and C3-4 to C3-12 in Table C; samples D1-1 to D1-5 in Table D; samples E1-4 to E1-12 in Table E; and the like are all included in the flattening method according to the present invention. Furthermore, it can be seen that more marked flattening effect is produced when the cluster size is 1000 or above. On the other hand, the irradiation conditions for sample A1-8 in Table A are the same as the conventional example in which a gas cluster ion beam is incident perpendicularly on the sample surface. Although conventional study results indicate that surface roughness can be reduced greatly, it can be seen that surfaces of composite materials can hardly be flattened. Principles of the flattening effect can be interpreted as follows. When applied, for example, to a composite material, which varies in the etching rate among different types of material, conventional flattening methods which use normal incidence on material surfaces produce steps. Thus, they cannot flatten the material or have limits. This is because conventional lateral sputtering is effective in a range of only a few nanometers, and etching rate differences among materials become prominent in a wider range (larger than a few nanometers). On the other hand, conventional methods which use irradiation angles smaller than 30° do not take cluster size into consideration. It has been found that at irradiation angles smaller than 30°, interaction with the material surface occurs in such a way as to leave a very long trail in the traveling direction of clusters. The present invention showed for the first time that to take effective use of this phenomenon, it is important to control the cluster size. It demonstrated experimentally that marked effect is produced when the cluster size is 50 or above and that very marked effect is produced when the cluster size is 1000 or above. Qualitatively, it is believed that there is a mechanism whereby increases in the cluster size cause very large interaction in the irradiation direction, resulting in marked increases in the flattening effect around cluster sizes of 50 and 1000. Also, from Table C, it can be seen that the flattening effect on composite material when the cluster size is varied does not depend on the type of composite material. This is because, as described above, the flattening is caused by a phenomenon in which gas clusters recoil from collisions with a material surface, grinding and etching tips of protrusions on any material. It further appears from the experimental results that the flattening effect of the present invention on composite material intrinsically does not have material dependence. That is, the effect of the present invention works similarly regardless of whether particles of different materials are dispersed in a mixture, particles of the same composition which differ in crystal orientation and crystallinity (the degree of amorphousness) are dispersed, or different types of materials are distributed as in the case of a multilayer film structure. Also, from Table B, it can be seen that the effect does not depend on the accelerating voltage of gas cluster ions. In view of the above mechanism, this indicates that the accelerating voltage of gas cluster ions greatly affects flattening speed, but does not depend much on the phenomenon in which gas clusters recoil from collisions with a material surface. That is, it appears that the accelerating voltage greatly affects kinetic energy and velocity of the gas cluster ions, but does not affect angles of recoil from collisions. From tables A, C, D, and E, it can be seen that the solid surface flattening effect of the present invention is similarly achieved by both chemically reactive SF6 gas clusters and chemically nonreactive Ar without depending on the type of gas cluster. From FIG. 5 which shows measurement results of experiment F, it can be seen that the irradiation angle θp at which marked flattening effect is produced changes with changes in a cycle of different materials (film thickness, grain size, etc. of each layer in a multilayer film). The larger the cycle of different materials, the smaller the irradiation angle θp of the gas cluster ion beam tends to be. This is an easy-to-understand phenomenon in view of the flattening mechanism according to the present invention described above. However, as shown in FIG. 5, it was experimentally shown that there is no simple relationship between the cycle of different materials and the irradiation angle θp at which the effect works and that the effect works suddenly at irradiation angles θp of 30°, 25°, and 20°. That is, the surface roughness can be reduced greatly if the irradiation angle θp is decreased to 25° or less when the composite material consists of a combination of different particles and the average grain size of the different particles or average crystal grain size is less than 1 μm, but not less than 100 nm or when the composite material has a multilayer film structure and the average film thickness of the layers is less than 1 μm, but not less than 100 nm. When the average grain size, average crystal grain size, or the average film thickness is 1 μm or above, the surface roughness can be reduced greatly if the irradiation angle θp is decreased to 20° or less. Although details of this mechanism is not clear, it is presumed that high density state which exists when gas clusters collide with the composite material or polycrystal surfaces is involved here. From experiment G, it can be seen that the flattening effect of the present invention on different materials is also applicable to lateral wall surfaces of micropatterns. Also, it can be seen that when there are simply two types of material, the present invention can be applied to them by regarding them as a composite material. This is an essential of the present invention. That is, it appears appropriate to state that the flattening effect of the present invention on composite material works if there are at least two different types of material. In order for the different types of material to coexist, it is sufficient if they simply exist in two locations. Thus, when there are simply two types of material as in the case of experiment G flattening cannot be achieved by conventional methods, and it is only by the present invention that marked flattening can be achieved. When the degree of damage on the material surfaces after the flattening process in experiment A is compared with results obtained by a conventional method, whereas with the conventional method, S penetrates 40 to 50 nm from the surface, causing damage, the present invention causes damage only to a depth of 10 nm or less. Thus, it can be seen that the present invention can flatten solid surfaces with minimal damage. According to the present invention, when using irradiation angles θp smaller than 30°, various modes are conceivable, including not only a mode which involves a fixed value, but also a mode which involves two stages and mode which involves repetition of continuous changes. The solid surface processing apparatus (flattening apparatus) according to the present invention shown in FIG. 1 allows mode and irradiation angle θp settings. The sample support 19 is mounted on a rotating shaft 31 supported by stationary plates 32a and 32b as can be seen, for example, from FIG. 6A which shows a side face of the irradiation angle setting mechanism 30 and FIG. 6B which shows the front face of the irradiation angle setting mechanism 30 and the controller 40. An encoder plate 35a of an angle detecting unit 35 is mounted between the rotating shaft 31 and stationary plate 32a to detect a rotation angle of the sample support 19, i.e., the irradiation angle θp of the gas cluster ion beam with respect to the to-be-flattened surface of the sample 20 mounted on the sample support 19, as a digital value. The controller 40 consists of an electrical circuit unit 35b, display unit 36, setting unit 37, control unit 38, and drive unit 39. A detected angle (irradiation angle) θc from the electrical circuit unit 35b of the angle detecting unit 35 is displayed in a current angle area 36a of the display unit 36. When a user sets a Fixed mode by manipulating a mode setting unit 37a of the setting unit 37 and enters a desired irradiation angle θp by manipulating an angle setting unit 37b, “Fixed” is displayed in a mode area 36b of the display unit 36, the set angle is displayed in a set angle area 36c, and the control unit 38 drives a motor 33 via the drive unit 39 so that the current angle θc will coincide with the set angle θp. When the user sets a Two Stage mode and enters θp1 and θp2 in sequence as irradiation angles, “Two Stage” is displayed in the mode area, the first set angle θp1 is displayed in the set angle area 36c and the second set angle θp2 is displayed in a set angle area 36d, and in a first stage process, the control unit 38 drives and controls the motor 33 so that the current angle θc in the set angle area 36c will coincide with the set angle θp1. In a second stage process, the motor 33 is driven and controlled such that the current angle θc in the set angle area 36d will coincide with the set angle θp2. When a user sets a Continuous Change mode and enters θp1 and θp2 in sequence as angles, “Continuous Change” is displayed in the mode area, the set angles θp1 and θp2 are displayed in the set angle areas 36c and 36d, respectively, and the control unit 38 controls the motor 33 so that the irradiation angle θp will change continuously, reciprocating between the two set angles θp1 and θp2. Incidentally, a size setting unit 37c of the setting unit 37 is used to input and set the cluster size of the gas cluster ion beam. The control unit 38 drives and controls the cluster size sorting mechanism 17 based on the input. The control unit 38 is a CPU (central processing unit) or microprocessor which causes the various types of display and driving of the motor 33 and the like to be performed based on a setting program. The setting unit 37 is an input means such as a keyboard. In the example described above, the strong magnetic deflection type cluster size sorting mechanism 17 based on a permanent magnet is used to control the cluster size. The cluster size is controlled using an angle at which clusters are emitted from the cluster size sorting mechanism 17. It is alternatively possible to clarify a relationship between the cluster size and emission angle in advance and provide a display area for the cluster size. Incidentally, the cluster size may be adjusted by limiting the size of clusters when they are generated in the cluster generating chamber 11 instead of using such a cluster size sorting mechanism 17.
	claims	1. A method for treating a tumor of a patient using positively charged particles in presence of an intervening object, comprising the steps of:positioning the intervening object between the tumor of the patient and an exit surface of an output nozzle system, said output nozzle system connected to a synchrotron using a beam transport system;predetermining an energy reduction of the positively charged particles resultant from the positively charged particles traversing the intervening object along a beam treatment path, the energy reduction determined as a function of relative rotational position of the patient and the beam treatment path; andgenerating a radiation treatment plan adjusting energy of the positively charged particles delivered from said synchrotron to the intervening object to yield a desired beam treatment energy of the positively charged particles entering the tumor after compensating for the energy reduction. 2. The method of claim 1, said step of generating a radiation treatment plan comprising an automated output of a computer implemented algorithm. 3. The method of claim 1, further comprising the step of:using a physical property of the intervening material to calculate the energy reduction of the positively charged particles resultant from the positively charged particles traversing the intervening object along the beam treatment path, said physical property comprising at least one of: (1) a density and (2) a pathlength of the positively charged particles in the intervening object along the beam treatment path. 4. The method of claim 3, said intervening object comprising an implanted device. 5. A method for treating a tumor of a patient using positively charged particles in presence of an intervening object, comprising the steps of:positioning the intervening object between the tumor of the patient and an exit surface of an output nozzle system, said output nozzle system connected to a synchrotron using a beam transport system;predetermining an energy reduction of the positively charged particles resultant from the positively charged particles traversing the intervening object along a beam treatment path, the energy reduction determined as a function of relative rotational position of the intervening object and the beam treatment path; andgenerating a radiation treatment plan adjusting energy of the positively charged particles delivered from said synchrotron to the intervening object to yield a desired beam treatment energy of the positively charged particles entering the tumor after compensating for the energy reduction;pre-generating a set of images of the intervening object using cations delivered from said synchrotron, passed through the intervening object, and detected by a scintillation detector; andcalculating the energy reduction using the set of images. 6. A method for treating a tumor of a patient using positively charged particles in presence of an intervening object, comprising the steps of:positioning the intervening object between the tumor of the patient and an exit surface of an output nozzle system, said output nozzle system connected to a synchrotron using a beam transport system; andpredetermining an energy reduction of the positively charged particles resultant from the positively charged particles traversing the intervening object along a beam treatment path, the energy reduction determined as a function of relative rotational position of the intervening object and the beam treatment path; andgenerating a radiation treatment plan adjusting energy of the positively charged particles delivered from said synchrotron to the intervening object to yield a desired beam treatment energy of the positively charged particles entering the tumor after compensating for the energy reduction,said intervening object comprising at least one of:a mechanical element used to position the patient for treatment; andan implanted device.
	claims	1. A mobile, graphite-moderated fission reactor, comprising:a pressure vessel defining an interior volume,an active core region located within the interior volume of the pressure vessel, the active core region including a fuel assembly and a reflector; andat least one control system including a plurality of control rod drive mechanisms, wherein at least a portion of the at least one control system is located in a control region within the interior volume of the pressure vessel, wherein the fuel assembly includes a plurality of fuel unit cells and a plurality of control unit cells, each unit cell including a longitudinally extending graphite body with a longitudinally extending channel with a cladding,wherein a fuel rod is positioned in the channel of each of the plurality of fuel unit cells and forms a fuel rod flow annulus between an outer surface of the fuel rod and an inner surface of the cladding of the channel of the fuel unit cell,wherein a plurality of fuel rod flow annulus features are attached to the inner surface of the cladding of the channel of the fuel unit cell,wherein the plurality of fuel rod flow annulus features are positioned at longitudinally separated locations in an axial direction of the fuel rod flow annulus,wherein, at each longitudinally separated location, the plurality of fuel rod flow annulus features are circumferentially distributed at radially equal intervals such that an angular separation of the plurality of fuel rod flow annulus features at each longitudinally separated location satisfies the relationship 360/N, where N is the number of fuel rod flow annulus features at the longitudinally separated location and N≥3,wherein the fuel rod flow annulus features at a first longitudinally separated location are rotationally offset relative to the fuel rod flow annulus features at an adjacent longitudinally separated location, andwherein the pressure vessel is sized for mobile transport using a ship, train or truck. 2. The mobile, graphite-moderated fission reactor according to claim 1, wherein an amount of the rotational offset of the fuel rod flow annulus features is half the angular separation of the fuel rod flow annulus features. 3. The mobile, graphite-moderated fission reactor according to claim 1, wherein the longitudinally separated locations are equally spaced in the axial direction of the annulus. 4. The mobile, graphite-moderated fission reactor according to claim 1, further including a shipping container, wherein the pressure vessel is contained within the shipping container. 5. The mobile, graphite-moderated fission reactor according to claim 1, wherein the plurality of fuel rod flow annulus features attached to the inner surface of the cladding of the channel of the fuel unit cell are a first plurality of fuel rod flow annulus features, andwherein a second plurality of fuel rod flow annulus features are attached to the outer surface of the fuel rod. 6. The mobile, graphite-moderated fission reactor according to claim 1, wherein a control rod is positioned in the channel of each of the plurality of control unit cells and forms a control rod flow annulus between an outer surface of the control rod and an inner surface of the cladding of the channel of the control unit cell, andwherein a plurality of control rod flow annulus features are attached to the inner surface of the cladding of the channel of the control unit cell. 7. The mobile, graphite-moderated fission reactor according to claim 6, wherein the plurality of control rod flow annulus features are circumferentially distributed at radially equal intervals. 8. The mobile, graphite-moderated fission reactor according to claim 6, wherein the plurality of control rod flow annulus features are equally spaced at longitudinally separated locations. 9. The mobile, graphite-moderated fission reactor according to claim 6, wherein the plurality of control rod flow annulus features are equally spaced at longitudinally separated locations, and wherein, at each longitudinally separated location, the plurality of control rod flow annulus features are circumferentially distributed at radially equal intervals. 10. The mobile, graphite-moderated fission reactor according to claim 9, wherein the control rod flow annulus features at successive, longitudinally separated locations are rotationally offset relative to each other. 11. The mobile, graphite-moderated fission reactor according to claim 9, wherein, at each longitudinally separated location, there are three or more control rod flow annulus features. 12. The mobile, graphite-moderated fission reactor according to claim 11, wherein the control rod flow annulus features at successive, longitudinally separated locations are rotationally offset relative to each other. 13. The mobile, graphite-moderated fission reactor according to claim 6, further including a shipping container, wherein the pressure vessel is contained within the shipping container. 14. The mobile, graphite-moderated fission reactor according to claim 6, wherein the plurality of control rod flow annulus features are positioned at longitudinally separated locations in an axial direction of the control rod flow annulus, wherein, at each longitudinally separated location, the plurality of control rod flow annulus features are circumferentially distributed at radially equal intervals such that an angular separation of the plurality of control rod flow annulus features at each longitudinally separated location satisfies the relationship 360/N, where N is the number of control rod flow annulus features at the longitudinally separated location and N≥3, andwherein the control rod flow annulus features at a first longitudinally separated location are rotationally offset relative to the control rod flow annulus features at an adjacent longitudinally separated location. 15. The mobile, graphite-moderated fission reactor according to claim 14, further including a shipping container, wherein the pressure vessel is contained within the shipping container. 16. The mobile, graphite-moderated fission reactor according to claim 14, wherein an amount of the rotational offset of the control rod flow annulus features is half the angular separation of the control rod flow annulus features. 17. The mobile, graphite-moderated fission reactor according to claim 6, wherein the plurality of control rod flow annulus features attached to the inner surface of the cladding of the channel of the control unit cell are a first plurality of control rod flow annulus features, andwherein a second plurality of control rod flow annulus features are attached to the outer surface of the control rod. 18. The mobile, graphite-moderated fission reactor according to claim 17, wherein the control rods are translatable relative to a guide structure, and wherein at least three longitudinally separated locations of the second plurality of control rod flow annulus features are present in the guide structure during translation of the control rods.
048266523	claims	1. An underground nuclear reactor comprising: a cylindrical pressure vessel; a stationary pile of splerical fuel elemetns located within a removable metal core vessel, said removable vessel being arranged within a cavity defined by said cylindrical pressure vessel; a solid, outer, side reflector jacket laterally disposed aganist an external surface of said removable core vessel; an inner reflector comprising a plurality of spherical graphite elements within said removable metal core vessel and surrounding said pile; a bottom reflector of spherical graphite elements located within said removable metal core vessel and beneath said pile of fuel elements; a roof reflector of spherical graphite elements resting directly on said pile of fuel elements within said removable metal core vessel; a pluralilty of tubular sleeves arranged in said inner reflector; a plurality of absorber rods displaceably arranged within said sleeves; wherein said removable metal core vessel is an upwardly open cage having a mesh or a plurality fof holes of limited dimensions so as to prevent passage of said fuel elements and spherical graphite elements therethrough, and is of a construction sufficient to support said graphite and fuel elements; and a removable cover mounted in an opening in said cylindrical presusre vessel of sufficient dimensions to enable installation and removal of said core vessel therethrough; a closeable opening for removing burnt-up fuel elements and graphite elements, said opening being located in a bottom portion of said removable metal core vessel. blower means mounted on said cover for forcing cooling gas in a primary loop downwardly through said pile of spherical fuel elements; and a gas conduction jacket associated with said blower means, said jacket being located in a free space above said roof reflector and defining a blower compression area and a blower suction area. cooling system means mounted on an inner surface of said pressure vessel for removing heat generated by said pile of spherical fuel elements. a cooling medium within said cooling system means; and means for maintaining a gas pressure in said primary loop higher than a cooling medium pressure in said cooling system means. cooling system means mounted on an inner surface of said pressure vessel for removing heat generated by said pile of spherical fuel elements under normal operaitng conditions and for removing decay heat under emergency operating conditions. a plurality of first passages aligned with said tubular sleeves and arranged in said cover; a plurality of means for covering said first passages; a plurality of means for driving said plurality of absorber rods arranged in said first passages; a second, centrally-located passage in said cover; means for covering said second passage; a blower means for forcing cooling gas in a primary loop downwardly through said pile of spherical fuel elements; means for driving said blower means arranged in said second passage. foundation means for supporting said cylindrical pressure vessel; means for covering said pressure vessel resting on said foundation means; and as hall enclosing said means for covering and for housing auxiliary and supply systems. 2. A nuclear reactor according to claim 1, 3. A nulcear reactor according to claim 1, further comprising: 4. A nuclear reactor according to claim 1, further comprising: 5. A nuclear reactor according to claim 1, wherein said fuel elements have a heavy metal load for extended retention time in a core of said fuel elements. 6. A nuclear reactor according to claim 4, further comprising; 7. A nuclear reactor according to claim 6, further comprising; 8. A nuclear reactor according to claim 1, further comprising; 9. A nuclear reactor according to claim 1, further comprising; 10. A nuclear reactor according to claim 1, further comprising: 11. A nuclear reactor as in claim 1, wherein spherical elements in said bottom reflector are of a same diameter as said spherical fuel elements. 12. A nuclear reactor as in claim 1, wherein spherical elements in said inner reflector are of a same diameter as said spherical fuel elements. 13. A nuclear reactor as in claim 1, wherein spherical elements in said roof reflector are of a same diameter as said spherical fuel elements. 14. A nuclear reactor as in claim 1, wherein said plurality of sleeves are mounted in a uniform distribution over said removable metal core vessel.
052971740	abstract	A safety system grade dropped rod detection system for a pressurized water reactor (PWR) utilizes core exit thermocouples arranged in multiple trains and hot and cold leg RTDs to generate a safety system grade rod stop signal. The system generates from the temperature signals a relative power deviation (RD) and a curvature index (CI), which is the spatial second derivative of RD for each fuel assembly. The CI signatures not only provide rapid, reliable detection of dropped control rods, but also clearly identify failed and failing thermocouples.
	description	This invention relates to a method of scanning a substrate through an ion beam in an ion implanter to provide uniform dosing of the substrate. The invention also relates to an ion implanter arranged to perform this method of scanning a substrate. Ion implanters are well known and generally conform to a common design as follows. An ion source produces a mixed beam of ions from a precursor gas or the like. Only ions of a particular species are usually required for implantation in a substrate, for example a particular dopant for implantation in a semiconductor wafer. The required ions are selected from the mixed ion beam using a mass-analysing magnet in association with a mass-resolving slit. Hence, an ion beam containing almost exclusively the required ion species emerges from the mass-resolving slit to be transported to a process chamber where the ion beam is incident on a substrate held in place in the ion beam path by a substrate holder. Ion beams of different shapes have been used in the past. Ribbon beams are well known and generally have a major axis that is greater in dimension than the substrate to be implanted and a minor axis much smaller than the substrate. Another common type of ion beam is the spot ion beam where the cross-sectional profile of the ion beam is much smaller in all directions than the substrate to be implanted. With either type of ion beam, the ion beam and substrate are moved relative to one another such that the ion beam scans the entire substrate surface with the aim of achieving a uniform ion implant across the whole of the substrate. For a ribbon beam, only one scan across the substrate is required, whereas multiple scans are required for a spot beam. Scanning may be achieved by (a) deflecting an ion beam to scan across a substrate that is held in a fixed position, (b) mechanically moving a substrate whilst keeping an ion beam path fixed or (c) a combination of deflecting an ion beam and moving a substrate. Our U.S. Pat. No. 6,956,223 describes an ion implanter of the general design described above that uses a spot beam. While some steering of the ion beam is possible, the implanter is operated such that ion beam follows a fixed path during implantation. Instead, a wafer is held in a substrate holder that is moved along two orthogonal directions to cause the ion beam to trace over the wafer following a raster pattern like that illustrated in FIG. 1. First, the wafer is moved continuously in a single direction (the fast-scan direction) to complete a first scan line. The substrate is then stepped down a short distance orthogonally (in the slow-scan direction), and then moved back along the fast-scan direction to form a second scan line across the wafer to overlap with the first scan line. This process is then repeated such that the combination of tracing scan lines punctuated by the stepwise movement results in the whole surface of the wafer seeing the ion beam. The series of scan lines that leads to a complete dosing of the wafer is referred to herein as a “pass”. An implant may comprise multiple passes over the wafer. Further improvements may be made to improve the uniformity of implants made using such raster scans. For example, multiple passes over the substrate may be made and interlacing may be effected (e.g. make a first pass implanting the first, fifth, ninth, etc. scan lines, then make a second pass implanting the second, sixth, tenth, etc. scan lines, then make a third pass, etc.). Also a problem of angular effects (i.e. off-normal incidence of the ion beam or asymmetries in the ion beam) may be addressed by making multiple passes with rotation of the wafer between passes. For example, in a quad implant four (or a multiple of four) passes are made with a 90° twist of the substrate between each pass. Changing the orientation of the wafer clearly helps alleviate such angular effects. Our U.S. patent application Ser. No. 11/527,594 (U.S. Patent Application Publication No. 2007/0105355) provides more details of such scanning techniques. While such techniques offer excellent uniformity in dosing, the need to perform multiple passes has an associated time overhead that reduces the throughput of the ion implanted. U.S. Patent Application Publication No. 2001/0032937 describes a very different method of scanning a substrate that does not rely solely on linear movement of the substrate relative to the ion beam. Instead, as illustrated in FIG. 2, a substrate is spun about its central axis with a constant angular velocity, while also being translated across a fixed position, elongate spot ion beam. Movement of the substrate effectively sees the ion beam travel through the centre of the substrate. The ion beam is unusual in that it is nether a conventional spot beam, nor is it a ribbon beam. Rather, it is elongated such that it has a longer major axis that is smaller than the width of the substrate. As the ion beam first clips the substrate, the rotation of the substrate sees the ion beam implant the periphery of the substrate: as the substrate is translated across the ion beam, the implanted region grows in width and spirals into the centre of the substrate before spiraling out and moving off the periphery of the substrate. However, the linear speed of the edge of the spinning substrate is much faster than the linear speed of the centre of the substrate. To compensate for this effect, the substrate is translated at a variable velocity through the ion beam such that its speed is greatest at the centre of the substrate. In practice, such a technique is difficult to implement. The control law for the translational velocity is complex and achieving accurate control of this varying velocity is problematic. Worse still, to achieve high uniformity of implant across the substrate requires exceptional uniformity in the ion beam. Against this background, and from a first aspect, the present invention resides in a method of scanning a substrate through an ion beam in an ion implanter, comprising: causing relative motion between the substrate and the ion beam such that the ion beam passes over all of the substrate; and rotating the substrate substantially about its centre while causing the relative motion. The relative motion is caused such that the ion beam would pass over all of the substrate even if the substrate were not rotating. Rotating the substrate while causing the relative motion between the substrate and the ion beam has several advantages. Briefly, problems of angular effects are overcome, uniformity is improved, throughput may be increased, and a greater range of ion beam profiles may be tolerated. More specifically, the velocity control law problem inherent in the arrangement of US2001/0032937 may be avoided. Where the ion beam is a ribbon beam, the method may comprise causing a relative motion between the substrate and the ribbon beam such that all of the substrate passes through the ribbon beam. This relative motion may be performed in one pass. Hence, a single scan line is formed. This method has some similarities with US2001/0032937. Instead of a tall spot beam, a ribbon beam is used. However this simple change has a huge benefit, namely that the relative motion between the substrate and the ion beam may be effected with a constant speed while still achieving a uniform implant. Hence, the complex velocity control law of US2001/0032937 is avoided. In addition to maintaining a constant speed of the relative motion, a constant rotational speed is also preferably employed. Where the ion beam is a spot ion beam, the method may comprise causing the relative motion between the substrate and the ion beam such that the ion beam passes over all of the substrate by causing a series of translations of the substrate relative to the ion beam such that the ion beam traces a series of scan lines over the substrate. Compared to US2001/0032937, forming multiple scan lines to cover the substrate as if it were not rotating sees a uniform implant when the relative motion is effected as a constant speed. Hence, the complex velocity control laws are avoided. These scan lines may be formed so as to be parallel or substantially parallel. The scan lines may all be formed in a common direction or may be formed by a reciprocal motion such that the scan lines extend back and forth. The scan lines may be arcuate. Alternatively, the scan lines may be linear such that a raster scan or saw-tooth scan is formed. The raster scan may be formed by performing a reciprocal motion in a fast-scan direction while performing an intermittent step-wise motion in a slow-scan direction. The saw-tooth scan may be formed by performing a reciprocal motion in a fast-scan direction while performing a continuous motion in a slow-scan direction. Preferably, scan lines are arranged so as to overlap. By this, it is meant that if the substrate were not to be spun, a series of overlapping regions of the substrate that are implanted during each movement along a scan line would result. Advantageously, the scan lines may be arranged so as to have minimal overlap. For example, if the scan lines have a pitch P and the ion beam a. dimension D in the pitch direction, the pitch may be just less than that dimension. As an example, the pitch P may be 5% or less than that dimension D. It may be greater than 0.9 times the dimension D. Put another way, the pitch may be approximately equal to the ion beam's dimension in the pitch direction, say 50 mm each. These values work well with disk-like substrates of 300 mm diameter, as are typical in the semiconductor wafer industry. With either type of ion beam, a motion is imparted between substrate and ion beam that sees a translational motion and a rotational motion. The translational motion may be achieved by translating the substrate or by scanning the ion beam (e.g. by electrostatic deflection), or by a combination of the two. The rotation preferably occurs for each scan line. The rotational motion has several advantages. First, the rotation helps overcome the problematic angular effects described above. Whereas quad implants alleviate these problems by using orientations of the substrate at four angles, the present invention provides a continuous range of angles in a single pass. Hence the need for time-consuming multiple passes is avoided. Preferably, the substrate is rotated such that it performs at least a complete revolution as the ion beam scans across a or each scan line. More preferably, the substrate is rotated so as to complete fifteen to twenty revolutions as the ion beam scans across a or each scan line. This means that the ion beam traces a spiral across the substrate that has a reasonable number of revolutions. Where the ion beam is a spot beam, the method may comprise rotating the substrate and/or causing the relative motion between the substrate and the ion beam such that the resulting spirals traced by the ion beam over the substrate overlap on adjacent revolutions. Other advantages are obtained by rotating the substrate while causing the relative motion between the substrate and ion beam. Uniformity of implant benefits greatly from this method, namely the uniformity of the dose received by different parts of the substrate. In addition, excellent uniformity may be achieved even where a large pitch is used between scan lines. To illustrate this, when performing a traditional raster scan where no rotation of the substrate is performed, pitches are chosen so as to provide a large overlap between adjacent scan lines in order to ensure good uniformity. This results in a large number of scan lines that lengthens the implant process. In contrast, only minimal overlap is required for the present invention. As a result, the pitch can be increased such that fewer scan lines are needed. This of course means that substrates may be implanted more quickly, thereby increasing the throughput of the ion implanter. Another advantage that follows from the general improvements in uniformity is that a larger range of beam profiles and imperfections may be tolerated. Optionally, the method may comprise causing relative motion between the substrate and the ion beam to form a scan line such that a point in the ion beam, having an average value of the total ion beam current along a section taken through the ion beam orthogonal to the direction of relative motion, passes over the centre of the substrate. Where multiple scan lines are formed, the positions of the other scan lines may be determined by the position of the scan line that passes through the centre of the substrate. For example, fixing the position of the central scan line and ensuring a desired pitch will dictate the position of the other scan lines. From further aspects, the present invention resides in a controller in an ion implanter arranged to implement the above methods and an ion implanter comprising such a controller. FIG. 3 shows a known ion implanter 10 for implanting ions in substrates 12, and that may be used to implement the present invention. Ions are generated by the ion source 14 to be extracted and follow an ion path 34 that passes, in this embodiment, through a mass analysis stage 30. Ions of a desired mass are selected to pass through a mass-resolving slit 32 and then to strike the semiconductor substrate 12. The ion implanter 10 contains an ion source 14 for generating an ion beam of a desired species that is located within a vacuum chamber 15 evacuated by pump 24. The ion source 14 generally comprises an arc chamber 16 containing a cathode 20 located at one end thereof. The ion source 14 may be operated such that an anode is provided by the walls 18 of the arc chamber 16. The cathode 20 is heated sufficiently to generate thermal electrons. Thermal electrons emitted by the cathode 20 are attracted to the anode, the adjacent chamber walls 18 in this case. The thermal electrons ionise gas molecules as they traverse the arc chamber 16, thereby forming a plasma and generating the desired ions. The path followed by the thermal electrons may be controlled to prevent the electrons merely following the shortest path to the chamber walls 18. A magnet assembly 46 provides a magnetic field extending through the arc chamber 16 such that thermal electrons follow a spiral path along the length of the arc chamber 16 towards a counter-cathode 44 located at the opposite end of the arc chamber 16. A gas feed 22 fills the arc chamber 16 with the species to be implanted or with a precursor gas species. The arc chamber 16 is maintained at a reduced pressure within the vacuum chamber 15. The thermal electrons travelling through the arc chamber 16 ionise the gas molecules present in the arc chamber 16 and may also crack molecules. The ions (that may comprise a mixture of ions) created in the plasma will also contain trace amounts of contaminant ions (e.g. generated from the material of the chamber walls 18). Ions from within the arc chamber 16 are extracted through an exit aperture 28 provided in a front plate of the arc chamber 16 using a negatively-biased (relative to ground) extraction electrode 26. A potential difference is applied between the ion source 14 and the following mass analysis stage 30 by a power supply 21 to accelerate extracted ions, the ion source 14 and mass analysis stage 30 being electrically isolated from each other by an insulator (not shown). The mixture of extracted ions are then passed through the mass analysis stage 30 so that they pass around a curved path under the influence of a magnetic field. The radius of curvature traveled by any ion is determined by its mass, charge state and energy, and the magnetic field is controlled so that, for a set beam energy, only those ions with a desired mass to charge ratio and energy exit along a path coincident with the mass-resolving slit 32. The emergent ion beam is then transported to the process chamber 40 where the target is located, i.e. the substrate 12 to be implanted or a beam stop 38 when there is no substrate 12 in the target position. In other modes, the beam may also be accelerated or decelerated using a lens assembly positioned between the mass analysis stage 30 and the substrate position. The substrate 12 is mounted on a substrate holder 36, substrates 12 being successively transferred to and from the substrate holder 36, for example through a load lock (not shown). The substrate holder 36 may be of any conventional design that provides linear translation of the substrate 12 in both x- and y-axis directions (the ion beam path 34 defining the z axis, and the x axis is taken to be horizontal and the y axis vertical), while also providing rotation of the substrate 12 about its centre. For example the possibilities include: a cantilevered scanning arm that effects linear movements like that described in U.S. Pat. No. 6,956,223 which is incorporated herein in its entirety; a scanning arm provided with rotary joints that are moved to effect scanning like those described in our co-pending U.S. patent application Ser. No. 11/588,432 which is incorporated herein in its entirety; or a reactive mass scanning arrangements like that described in our co-pending U.S. patent application Ser. No. 11/589,312 which is incorporated herein in its entirety. The ion implanter 10 operates under the management of a controller, such as a suitably programmed computer 50. The controller 50 controls scanning of the wafer 12 through the ion beam 34 to effect desired scanning patterns. FIG. 4 shows the motion described by the substrate 12 as it is scanned through the ion beam 34 by the controller 50. The substrate 12, in this embodiment, is a standard 300 mm silicon wafer commonly used in the semiconductor industry. Of course, other sizes and types of wafers may be used. The ion beam 34 is a typical spot beam with a reasonably uniform diameter of 50 mm. The controller 50 may manage operation of the ion implanter 10 to control, to a certain extent, the size and shape of the ion beam 34. For example, the controller 50 may vary operational properties of the ion source 14 or of ion optics that guide the ion beam 34 through the ion implanter 10. Some steering of the ion beam 34 is possible, although generally the ion beam 34 will be fixed as the wafer 12 is mechanically scanned therethrough. The controller 50 directs the substrate holder 36 to scan the wafer 12 through the ion beam 34 to follow the raster scan indicated at 52. The raster scan 52 comprises a series of scan lines 54 formed in alternate directions by reciprocal motion of the wafer 12 in the fast scan direction (left and right along the x-axis direction), separated by steps 56 formed by periodic stepwise motion in the slow scan direction (downwardly in the y-axis direction). Hence, the motion of the wafer 12 in the fast scan direction must be reversed between successive scan lines 54, while its motion in the slow scan direction is in the same direction. Simultaneously, the controller 50 directs the substrate holder 36 to spin the wafer 12 about its centre. The direction of spin is indicated in FIG. 4 and is kept the same for all scan lines 54 (and this can be either clockwise or anti-clockwise, as is desired). The wafer 12 is translated at 360 mm/sec and is rotated at 1200 rpm, leading to approximately twenty revolutions per scan line 54. Other values may be chosen. For example, the spin speed may be varied although a speed sufficient to allow 15 to 20 revolutions of the wafer 12 along each scan line 54 is preferred. An advantage of rotating the wafer 12 while moving the wafer 12 through the ion beam 34 along each scan line 54 is that a larger pitch between adjacent scan lines 54 may be realised without compromising uniformity of implant: in this embodiment a pitch of 50 mm was used. In a conventional raster scan, where no rotation of the wafer 12 is performed, such a pitch would lead to there being only minimal overlap between the stripes of wafer 12 dosed as adjacent scan lines 54 are formed. A further advantage of rotating the wafer 12 while moving the wafer 12 along each scan line 54 is that the problematic angular effects described above are avoided. This is because rotating the wafer 12 ensures that the wafer 12 sees the ion beam 34 over the full range of 360°. It is not so straightforward to envisage how the combined translation and rotation of the wafer 12 provides another advantage, namely uniformity of implant of the wafer 12. However, an understanding becomes readily apparent when the implant process is thought of in the following way. Rather than considering the scan lines 54 of the raster pattern 52 being formed successively, they may be thought of as being formed concurrently, i.e. all scan lines 54 are formed in one pass of a plurality of spot ion beams 34 over the wafer 12. The size of each ion beam 34 and the pitch used means that the plurality of spot ion beams 34 overlap and so may be regarded as a virtual ribbon beam 60, as shown in FIG. 6. FIG. 5 shows how the intensity of this virtual ribbon beam 60 in the slow scan direction is derived from the individual spot beams 34. The ion beam current profiles 62 of the spot ion beams 34 at each scan line 54 is shown, and adding these individual contributions provides the current profile 64 of the virtual ribbon beam 60. The resulting profile 64 of the virtual ribbon beam 60 has a broadly flat top that extends over the height of the wafer 12. However, in practice the individual profiles 62 do not add to form a perfectly flat top, but instead the top exhibits a periodic ripple 66. To demonstrate that spinning the wafer 12 does not have a detrimental effect on dosing uniformity, first consider a hypothetical perfect ribbon beam, i.e. a ribbon beam exhibiting no ripple 66 but instead having a perfect flat top in the region that passes over the wafer 12. Clearly, passing a wafer 12 through this perfect ribbon beam without spinning the wafer 12 will lead to a perfect uniform implant. It is easy to see that spinning the wafer 12 while it passes through the perfect ribbon beam will have no detrimental effect as all points on the wafer 12 will still see exactly the same total amount of ion beam current. To appreciate that spinning the wafer 12 in fact has a beneficial effect on the uniformity of implant, we should return to the rippled virtual ion beam 60 that is equivalent to our multiple passes of a spot ion beam 34 over the wafer 12. Passing the wafer 12 through this virtual ion beam 60 without spinning the wafer 12 results in any particular point on the wafer 12 seeing only one particular part of the ripple 66 on the virtual ion beam 60. For example, a first point may pass through a peak in the ripple 66 and a second point may only pass through a trough in the ripple 66. Hence, the first point will receive a greater dose than the second point. Considering the wafer 12 as a whole, the dose it receives will exhibit stripes extending in the fast-scan direction. Put another way, the wafer 12 will have stripes due to lines of high dose corresponding to peaks in the ripple 66 and lines of low dose corresponding to troughs in the ripple 66: the high doses correspond to points on the wafer 12 that see the centre of the spot ion beam 34 pass overhead and the low doses correspond to points on the wafer 12 that see the outer edges of the spot ion beam pass overhead. Turning now to a combination of translating and spinning the wafer 12, it can be appreciated that any point on the wafer 12 (the centre point aside) will see different parts of the virtual ion beam 60 as it spins with the wafer 12. FIG. 6 shows schematically the equivalent movement of the wafer 12 through the virtual ribbon beam 60, with arrow 68 indicating the translation of wafer 12 and arrow 70 indicating the rotation of wafer 12. FIG. 7 shows the wafer 12 further translated in the fast-scan direction towards virtual ribbon beam 60, at a point where it just contacts the beam 60. Taking a point P1 on the periphery of the wafer 12, it will rotate with the wafer 12 in the direction 72. In FIG. 7, point P1 just clips the central part of virtual ribbon beam 60. The ripple 66 in the virtual ribbon beam 60 is shown to the right in FIG. 7. As the point P1 rotates to clip the centre of the virtual ribbon beam 60, it effectively scans down a central segment 74 of the ripple 66, as indicated in FIG. 7. As will be understood, segment 74 is initially very small as the wafer 12 first clips the virtual ribbon beam 60, and segment 74 then expands as the wafer 12 is driven further into the virtual ribbon beam 60. FIG. 8 shows the wafer 12 further translated in direction 68 such that the leading edge of the wafer 12 is now a little way clear of the far side of virtual ribbon beam 60. Point P1 spinning on the edge of the wafer 12 now passes through the virtual ribbon beam 60 before emerging on the far side of the beam 60, before passing back through the beam 60 once more. As shown to the right in FIG. 8, this results in point P1 scanning down two separate segments 76 and 78 of the ripple 66. Considering the gradual movement of the wafer 12 into the virtual ribbon beam 60 that will occure between the stages shown in FIGS. 7 and 8, the single segment 74 in the ripple 66 of FIG. 7 expands until the leading edge of the wafer 12 breaks clear of the far side of the virtual ribbon beam 60 at which point the single segment 74 divides into the two segments 76 and 78. As the wafer 12 continues its motion, segments 76 and 78 move outwardly along the ripple 66 as the point P1 intercepts the beam 60 further and further towards the beam's edges. FIG. 9 shows the wafer 12 driven into the virtual ribbon beam 60 such that the beam 60 extends across the centre of the wafer 12. In this position, the segments 76 and 78 have moved outwardly along the ripple 66 to be at their extremes. As motion of the wafer 12 through the virtual ribbon beam 60 continues, the segments 76 and 78 move back inwardly across the ripple 66 to join once more as a central segment 74. Thus, the overall movement of the wafer 12 through the virtual ribbon beam 60 is such that point P1 sees virtually all the ripple 66. The effect of point P1 scanning over all the peaks and troughs in the ripple 66 is that point P1 sees what will be close to the average ion beam current rather than just seeing a single value as was the case described above where the wafer 12 is not spun. Clearly, the more peaks and troughs that are sampled, the closer the dose seen by point P1 will be to the average. FIG. 10 shows the wafer 12 and virtual ribbon beam 60 once more, but this time considers a second point P2 that resides inward of the edge of the wafer 12, in this case about a quarter of the way in a long a radius. As wafer 12 spins, point P2 follows the path indicated by the circle 80. As the wafer 12 passes through the virtual ribbon beam 60, point P2 first scans the central segment 74 of the ripple 66 and then the pair of segments 76 and 78. After the pass of the wafer 12 through the virtual ribbon beam 60, point P2 has seen the segment 82 of the ripple 66 indicated in FIG. 10. As point P2 is inset from the edge of the wafer 12, segment 82 extends across only a fraction of ripple 66 with a width corresponding to the diameter of circle 80. As a result, point P2 samples a smaller part of the ripple 66 than point P1 that was on the edge of the wafer 12. Nonetheless, point P2 still sees multiple peaks and troughs in the ripple 66 and so sees an averaged amount of ion beam current. As we take other points that reside closer and closer towards the centre of the wafer 12, the segment 82 of the ripple 66 scanned by the point gets ever and ever smaller such that the number of peaks and troughs seen by the point decreases. As a result, the averaging effect works less and less well. Eventually, points are reached that do not see a full cycle of the ripple 66. FIG. 11 shows such a point P3 that resides just a small distance from the centre of the wafer 12. Point P3 follows circle 80 as the wafer 12 spins, and mapping the diameter of circle 80 to the ripple 66 shown to the right in FIG. 11 shows that only a small segment 82 of the ripple 66 is seen by point P3. The detail from the ripple 66 shown in the far right of FIG. 11 demonstrates that, in this embodiment, the segment 82 seen by point P3 sits in a trough of the ripple 66. As a result, point P3 always receives ion beam current that sits below the average ion beam current value shown at 84 in the detail. Hence, point P3 receives a below average dose during the implant. This potential problem may be overcome by careful selection of which part of the ion beam 34 traces across the centre of the wafer 12. FIG. 12 corresponds to the detail of FIG. 11, but shows that ripple 66 shifted such that the centre of the wafer 12 (indicated by line 86) passes through the ripple 66 where its value is equal to the average current value 84. Hence, the centre point of the wafer 12 will see the average current value (as it effectively traces a line through the virtual ribbon beam 60). Moreover, points further and further away radially from the centre of the wafer 12 will see the segments 82 of the ripple 66 that they sample expand across the ripple 66 symmetrically, as indicated by arrow 88, such that they are symmetric about the average ion beam current. Hence, each point sees an average amount of ion beam current irrespective of its position on the wafer 12. FIG. 13 shows how this notional aligning of the average current 84 of the ripple 66 with the centre 86 of the wafer 12 relates to the actual situation of scanning the wafer 12 relative to the spot beam 34 along the series of scan lines 54. The left hand side of FIG. 13 shows a series of scan lines 54 extending across the wafer 12, each scan line 54 corresponding to the centre of the spot ion beam 34 and hence the peak in its current profile 62. The centre of the wafer 12 is also shown by line 86. The right hand side of FIG. 13 corresponds to FIG. 5 and shows the virtual ribbon beam 60 created by the spot ion beam 34 as it travels along the scan lines 54. The ripple 66 on the virtual ribbon beam 60 is correctly aligned such that it is at its average value 84 at the centre line 86. As can be seen, the peaks in the ripple 66 correspond to the peaks in the individual current profiles 62, and hence the position of scan lines 54 shown across the wafer 12. The troughs in the ripple 66 correspond to the midpoints between scan lines 54. Typically, the average current value 84 occurs half-way between a peak and a trough and so corresponds to a quarter of the way from one scan line 54 to the next 54. Hence, if the scan lines 54 are spaced with a pitch T, the scan line 54 closest to the centre of the wafer 12 should be formed by scanning the wafer 12 such that the centre of the spot ion beam 34 passes along a line offset by T/4 from the centreline 86 of the wafer 12. The remaining scan lines 54 may be arranged according to the pitch spacing T. The present invention may be used with scan patterns other than the raster pattern illustrated in FIG. 4. For example, the controller 50 may direct the substrate holder 36 to effect a constant motion in the slow-scan direction rather than the stepped motion described above. Implementing the same reciprocal motion in the fast scan direction causes the ion beam 34 to trace a saw-tooth scan pattern 90 like that shown in FIG. 14. As before, spinning the substrate 12 while performing this saw-tooth scan also results in uniform dosing of the wafer 12. This can be appreciated by equating the single saw-tooth scan pattern 90 to a pair of scan patterns 90a and 90b that are rotated relative to one another as shown in FIG. 14. Each scan pattern 90a and 90b comprises a series of parallel scan lines akin to the raster pattern 52 already described. Each scan pattern 90a and 90b will see uniform dosing of the wafer 12 in the same way as for the raster patterns 52. Of course, performing these two uniform scan patterns 90a and 90b will result in an overall uniform scan pattern 90. The skilled person will appreciate that changes may be made to the above-described embodiment without departing from the scope of the present invention. For example, the dimensions of the substrate 12 and the ion beam 34 may be changed, as may the pitch spacing, the angular velocity of the spinning substrate 12 and the scanning speed of the substrate 12. For example, the invention may be used with a variety of substrates 12. For example, substrate material and substrate shape and dimensions may be varied without departing from the scope of the present invention. The dimensions of the ion beam 34 may also be varied. Varying the dimensions of the ion beam 34 may require a consideration of at least some of the other parameters affecting the scanning. For example, changing the height of the ion beam 34 (i.e. the dimension in the slow-scan direction) may necessitate a change in the pitch spacing. Remembering how the virtual ribbon beam 60 is formed by the overlapping ion beams 34 corresponding to the ion beam's position at adjacent scan lines 52 shown in FIG. 5, decreasing the height of the ion beam 34 may necessitate a reduction in pitch to ensure overlap between adjacent scan lines 52. Conversely, increasing the ion beam height may allow the pitch spacing to be increased without adversely affecting dose uniformity. Varying the width of the ion beam 34 (i.e. the dimension in the fast-scan direction) may necessitate a change in the spin speed and/or translation speed of the wafer 12. This is illustrated in FIGS. 15a and 15b. FIG. 15a shows a wafer 12 being translated along line 68 through a wide ion beam 34 while the wafer 12 is spun in direction 72. Wide ion beam 34 traces a wide spiral 92 over the wafer 12 during motion (only part of the spiral 92 traced during a single revolution is shown in FIG. 15a). The spin speed of the wafer 12 is selected such that adjacent parts of the spiral 92 overlap, as will be clear from FIG. 15a. FIG. 15b corresponds to FIG. 15a, but shows a narrower ion beam 34. Translating the wafer 12 at the same speed and spinning the wafer 12 at the same speed results in adjacent parts of the spiral 92 no longer overlapping. To ensure that overlap is acquired, either the wafer 12 should be spun more quickly or the wafer 12 should be translated more slowly. Obviously, the reverse of the above situations is true, namely that a change in pitch, translation speed or spin speed may require adjustment of the ion beam dimensions in the fast and slow scan directions. A further parameter that may be varied is the offset of the centre of the ion beam 34 from the centre of the wafer 12, and the consequent arrangement of adjacent scan lines 52. The above arrangement demonstrates how uniform dosing may be achieved by ensuring a point in the ion beam 34 having average current passes through the centre line 86 of the wafer 12. Where this average current resides in the ion beam 34 is of course dependent upon the ion beam profile itself. Determining ion beam profiles is well known in the art, see for example our co-pending U.S. patent application Ser. Nos. 11/589,156 and 11/029,004. Determining the average position from such a profile is straightforward. Variations in how the relative movement between ion beam 34 and wafer 12 is effected are possible. For instance, the ion beam 34 may be made to move relative to the substrate 12 rather than the arrangement described above. Realistically, the substrate 12 will be rotated rather than trying to spin the ion beam 34 around the substrate 12, but the ion beam 34 may be scanned in a raster pattern 52 across a spinning substrate 12. The scan pattern achieved using relative motion between the wafer 12 and ion beam 34 may also be varied. A traditional square raster pattern 52 is shown in FIG. 4, and a saw-tooth pattern 90 is shown in FIG. 14, but others are possible. For example, a series of arcuate scan lines is possible, whether those arcs correspond to a series of concentric, variable radius arcs (like those that may be created using the scanning arm of our co-pending U.S. application Ser. No. 11/588,432) or to a series of non-concentric arcs of fixed radius. The latter pattern results in a series of arcs that are not parallel, but are considered as being substantially parallel. The above embodiments describe using a spot ion beam 34 to form a series of scan lines 52 by translating the substrate 12 while also rotating the substrate 12. This creates a virtual ribbon beam 60. However, the present invention may be implemented with an actual ribbon beam. For example, a substrate 12 may be translated through a ribbon beam in the usual way but, at the same time, the substrate 12 may be rotated. Thus, any non-uniformities in the ribbon beam will be averaged out over the spinning substrate 12 such that improved uniformity is achieved.
	abstract	Two or more-staged masks are prepared for a charged beam generating source. One mask has first aperture sections having rectangular apertures arranged into a lattice form, and electrodes which deflects a beam at respective first aperture sections. The other mask has a second aperture section having basic figure apertures for shaping the beam which passes or passed through the first aperture sections. Layout data of a semiconductor apparatus are divided into sizes of the basic figures which take reduction in exposure into consideration so as to be classified according to the basic figures. The beam which is shaped into a form of an overlapped portion of the divided layouts and the classified basic figure is emitted onto a sample.
061513768	summary	TECHNICAL FIELD The present invention relates to a nuclear fuel assembly with a substantially square cross section for a light water reactor comprising a plurality of fuel rods extending between a top tie plate and a bottom tie plate. BACKGROUND OF THE INVENTION In a nuclear reactor, moderated by means of light water, the fuel exists in the form of fuel rods, each of which contains a stack of pellets of a nuclear fuel arranged in a cladding tube. The cladding tube is normally made of a zirconium-base alloy. A fuel bundle comprises a plurality of fuel rods arranged in parallel with each other in a certain definite, normally symmetrical pattern, a so-called lattice. The fuel rods are retained at the top by a top tie plate and at the bottom by a bottom tie plate. To keep the fuel rods at a distance from each other and to prevent them from bending or vibrating when the reactor is in operation, a plurality of spacers are distributed along the fuel bundle in the longitudinal direction. A fuel assembly comprises one or more fuel bundles, each extending along the main part of the length of the fuel assembly. Together with a plurality of other fuel assemblies, the fuel assembly is arranged in a core. The core is immersed into water which serves both as coolant and as neutron moderator. During operation, the water flows from below and upwards through the fuel assembly, whereby, in a boiling water light-water reactor, part of the water is transformed into steam. The percentage of steam increases towards the top of the fuel assembly. Consequently, the coolant in the lower part of the fuel assembly consists of water whereas the coolant in the upper part of the fuel assembly consists both of steam and of water. This difference between the upper and lower parts gives rise to special problems which must be taken into consideration when designing the fuel assembly. This problem can be solved by providing a flexible fuel assembly which in a simple manner may be given a shape where the upper part of the fuel assembly differs from the lower part so that optimum conditions may be obtained. A fuel assembly for a boiling water reactor with these properties is shown in PCT/SE95/01478 (Int. Publ. No. WO 96/20483). This fuel assembly comprises a plurality of fuel units stacked on top of each other, each comprising a plurality of fuel rods extending between a top tie plate and a bottom tie plate. The fuel units are surrounded by a common fuel channel with a substantially square cross section. A fuel assembly of this type may in a simple manner be given different designs in its upper and lower parts. Also in a light-water reactor of pressurized-water type, it may be desirable to design the fuel assemblies so that each fuel assembly comprises a plurality of fuel units stacked on top of each other. As described above, each of the fuel units then comprises a plurality of fuel rods extending between a top nozzle and a bottom nozzle. A fuel assembly for a pressurized-water reactor, however, comprises no fuel channel. One factor which must be taken into consideration when designing fuel units which are of the order of magnitude of 300-1500 millimeters long is that fission gases are formed during nuclear fission. In addition, the column of fuel pellets expands because of the heat formed in the fuel pellets. To take care of the fission gases and the thermal expansion of the column of fuel pellets, normally a relatively large space, an axial gap, is formed above the uppermost fuel pellet in the cladding tube in known full-length fuel rods, that is, fuel rods of the order of size of 4 metres long. The axial gap is of the order of size of 200-300 millimeters long. To this axial gap, the fission gases may thus diffuse and the column of fuel pellets may expand inwardly here. Thus, the axial gap contains no fissionable material. Another factor which must be taken into consideration when designing axial gaps is that the temperature of the cladding tube in this region is lower than in the rest of the cladding tube because no fuel pellet is arranged in the axial gap. A problem which may arise as a result thereof is that hydrogen, formed, among other things, upon corrosion of the cladding tube, which is of a zirconium based alloy, and is absorbed thereby, will diffuse into this colder region. In the event that the concentration of hydrogen becomes too high in this region, hydrides are formed in the cladding material and cause embrittlement thereof. In a serious case, the cladding tube may burst and fissionable material may enter the cooling water. A tendency to the same type of problems may also appear in regions between the pellets, that is, where a lower end of a fuel pellet makes contact with an upper end of an adjacently located fuel pellet, and in the region between two fuel units stacked on top of each other. The risk of embrittlement because of too high a concentration of hydrogen increases, to a certain limit, with the size of the axial gap. It is known to reduce the release of fission gas in different ways. One such way is to provide one or more of the fuel pellets with through-holes in their axial directions. In this way, the temperature in the fuel pellet is reduced, whereby the release of fission gas is reduced and the axial gap may be reduced. In this case, however, an axial gap of the order of size of a few millimeters is needed in a rod with a length of the order of size of 300 millimeters, up to a few tens of a millimeter for longer rods, to allow the thermal expansion of the column of fuel pellets. The object of the present invention is to provide a fuel assembly for a light-water reactor with a plurality of short fuel units wherein at least one fuel assembly is designed with an axial gap and with means for taking care of hydrogen diffusing into this gap, thus preventing the build-up of impermissibly high concentrations of hydrogen in the material surrounding the axial gap. SUMMARY OF THE INVENTION The present invention relates to a fuel assembly comprising a fuel rod with an axial gap for accumulation of fission gases, formed during operation, and thermal expansion of the nuclear fuel. The fuel rod comprises a cladding tube and a stack of fuel pellets arranged therein, a column with extruded fuel cylinders or an unbroken column of vibration-compacted fuel powder. The cladding tube is sealed by a plug at either end, more particularly with a top plug and a bottom plug, respectively. At the space without fissionable material, the fuel rod is provided with a larger material thickness than the remaining part of the fuel rod. In an advantageous embodiment of the invention, this material thickness is achieved in the top plug. The top plug is then provided with a cavity facing the uppermost fuel pellet arranged in the cladding tube. The top plug is preferably connected to the cladding tube in such a way that its inner diameter corresponds to the inner diameter of the cladding tube and is thickened radially outwardly. In this way, the column of fuel pellets is allowed to expand upwardly and into the top plug because of thermal expansion. By forming the fuel rod around the axial gap with a larger thickness, the hydrogen-absorbing capacity is increased here. By increased hydrogen absorption, the hydrogen concentration is reduced in the space to a corresponding extent and hence also the risk of embrittlement in the upper part of the fuel rod. The advantage of the invention is that the risk of embrittlement due to too high hydrogen concentration in the axial gap for thermal expansion and fission gases is reduced by an increase of the quantity of material and hence the hydrogen-absorbing capacity in this region. The increased quantity of material in the upper part of the fuel rod also entails improved mechanical properties of the upper part in question since it reduces the influence of the stresses in the material which arise because of the fission gases collected in this space. Another advantage of the invention is that the increased quantity of material in the upper part of the fuel rod entails an improved resistance to damage to the cladding tube in this region caused by abrasion and corrosion and/or erosion. In connection with repair and service of a nuclear reactor, foreign matter (or debris), such as metal chips, may enter the coolant. The debris is then transferred with the coolant when this is circulated through the core. Such debris may in certain cases give rise to abrasion damage on the cladding tube. The abrasion damage may in certain cases arise on a level with the top tie plate as a result of the debris adhering thereto and remaining there. When it is brought into vibration by the coolant which flows past, it wears on the cladding tubes which surround the fuel pellets. In the worst case, the abrasion damage may lead to fissionable material entering the cooling water. Still another advantage is that mixing vanes may be arranged in a simple manner at the upper end of the fuel rod.
	claims	1. A composition for transmuting a radioactive substance into a non-radioactive substance, comprising a mixed culture of microorganisms comprising:a radiation-resistant microorganism selected from the group consisting of Deinococcus sp., and Bacillus sp.;a yeast selected from the group consisting of Cryptococcus sp., Saccharomyces sp. and Trichosporon sp.;a fungus selected from the group consisting of Irpex sp. and Phanerochaete sp.;a photosynthetic bacteria species selected from the group consisting of Rhodobacter sp.; Chlorobium sp., Chromatium sp., Rhodospirillum sp., and Rhodopseudomonas sp.; anda green algae selected from the group consisting of Trebouxia sp., Stichococcus sp., Eliptochloris sp. and Coccomyxa sp;wherein each of the microorganisms is present at a concentration of 0.5×102 CFU/ml to 2.5×1010 CFU/ml. 2. The composition according to claim 1, wherein the radiation-resistant microorganism is selected from the group consisting of Deinococcus radiodurans, Bacillus safensis and Bacillus pumilus; the yeast is selected from the group consisting of Saccharomyces boulardii, Saccharomyces servazzii, Saccharomyces cerevisiae, Trichosporon cutaneum and Trichosporon loubieri; the fungus is selected from the group consisting of Irpex lacteus, Irpex hydnoides, Phanerochaete chrysosporium and Phanerochaete sordida; the photosynthetic bacterial species is selected from the group consisting of Rhodobacter sphaeroides and Rhodobacter capsulatus; andthe green algae is selected from the group consisting of Coccomyxa viridis and Stichococcus sp. 3. The composition according to claim 1, wherein the microorganisms are present in a total amount of 0.05% by weight to 60% by weight, based on the weight of the composition. 4. The composition according to claim 1, wherein the radioactive substance is cesium (Cs), uranium, iodine, strontium, iridium, radium or plutonium. 5. The composition according to claim 1, further comprising an environmentally acceptable carrier. 6. The composition according to claim 1, wherein the composition is used to dispose of radioactive waste or to treat soil, groundwater or wastewater, contaminated with radioactive substances. 7. A method for preparing the composition for transmuting a radioactive substance into a non-radioactive substance as set forth in claim 1, the method comprising:culturing the radiation-resistant microorganisms, the yeast, the fungi, the photosynthetic bacteria, and the green algae in culture medium individually or at least partially together; andmixing the cultured microorganisms to form the composition. 8. The method according to claim 7, wherein the microorganisms are cultured at a temperature of 20° C. to 40° C. for 12 hours to 7 days. 9. The method according to claim 7, wherein the cultured microorganisms are mixed with stirring.
039768899	summary	FIELD OF THE INVENTION The present invention relates to an X-ray diagnostic apparatus for X-ray exposures, having preset X-ray tube voltage and current values, and a preset exposure time and, more particularly, to an apparatus of this type which includes a plurality of filters in conformance with an exposure program for the X-radiation adapted to be selectively employed in coordination with a particular exposure object. DISCUSSION OF THE PRIOR ART An X-ray diagnostic apparatus of this type, for example, it utilized in the formation of dental exposures. In order to provide coordination with the particular object which is to be filmed, it is known to employ a timing switch or an mAs-relay. It is also known that operating keys may be used for the control of the mAs-relay, which are associated with the individual teeth. Prior to the completion of an exposure the key associated with a particular tooth which is to be X-rayed, must be depressed for effecting selection of the corresponding mAs-product. The determination of the mAs-product is carried out by means of an electronic switching installation which is influenced by the operating key. The electronic components are located in a panel which is associated with a single housing-like constructed X-ray diagnostic apparatus, and which also supports the exposure triggering mechanism. SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an X-ray diagnostic apparatus of the above-described type having a construction which, in comparison with the state of the technology, is essentially greatly simplified and considerably less expensive. In particular, there is thus obviated the need for a special control panel for the setting of the exposure data. The foregoing object is inventively attained through the provision of an X-ray diagnostic apparatus for X-ray exposures having fixedly set values for the X-ray tube voltage and current, and the exposure time and wherein for a particular exposure program a plurality of filters are provided for the X-radiation in coordination with a particular exposure object and in which a support arrangement is provided for the filters, through the intermediary of which a filter may be selectively interposed into the path of the X-radiation. Thus, pursuant to the inventive object, the coordination of the filter and the particular object which is to be exposed is carried out by interposing the particularly required filter into the path of the X-radiation. The arrangement which supports the filters may be directly positioned on the housing which contains the X-ray tubes. The inventive X-ray diagnostic apparatus is particularly adapted to the completion of dental exposures, in which the X-ray tubes and the high-voltage generator are located in an oil-filled housing, and the support arrangement for the filters is located intermediate an X-ray outlet aperture and a tube which focuses the X-radiation.
056429550	summary	FIELD OF THE INVENTION This invention relates to tooling which is useful in installing hardware in a nuclear reactor. In particular, the invention relates to tooling for installing hardware for stabilizing the core shroud of a nuclear reactor to resist deflection in response to a seismic event and/or loss-of-coolant accident (LOCA). BACKGROUND OF THE INVENTION A conventional boiling water reactor (BWR) is shown in FIG. 1. Feedwater is admitted into a reactor pressure vessel 10 via a feedwater inlet 12 and a feedwater sparger 14, which is a ring-shaped pipe having suitable apertures for circumferentially distributing the feedwater inside the reactor pressure vessel (RPV). The feedwater from sparger 14 flows downwardly through the downcomer annulus 16, which is an annular region between RPV 10 and core shroud 18. In addition, a core spray inlet 11 supplies water to a core spray sparger 13 (located inside the shroud 18) via core spray header 15, core spray downcomer piping 17 and core spray elbow 19 (which penetrates the shroud wall). The core spray header 15 has a circular section that occupies space directly underneath feedwater sparger 14. Core shroud 18 is a stainless steel cylinder surrounding the nuclear fuel core. The core is made up of a plurality of fuel bundle assemblies 22 (only two 2.times.2 arrays of which are shown in FIG. 1). Each array of fuel bundle assemblies is supported at the top by a top guide 20 and at the bottom by a core plate 21. The core top guide 20 provides lateral support for the top of the fuel assemblies and maintains the correct fuel channel spacing to permit control rod insertion. The water flows through downcomer annulus 16 to the core lower plenum 24. The water subsequently enters the fuel assemblies 22, wherein a boiling boundary layer is established. A mixture of water and steam enters core upper plenum 26 under shroud head 28. Vertical standpipes 30 atop shroud head 28 are in fluid communication with core upper plenum 26. The steam-water mixture flows through standpipes 30 and enters steam separators 32, which are of the axial-flow centrifugal type. The separated liquid water then mixes with feedwater in the mixing plenum 33, which mixture then returns to the core via the downcomer annulus. The steam passes through steam dryers 34 and enters steam dome 36. The steam is conducted from the RPV via steam outlet 38. The BWR also includes a coolant recirculation system which provides the forced convection flow through the core necessary to attain the required power density. A portion of the water is pumped from the lower end of the downcomer annulus 16 via recirculation water outlet 42 and forced by a centrifugal recirculation pump (not shown) into jet pump assemblies 44 (only one of which is shown) via recirculation water inlets 46. The BWR has two recirculation pumps, each of which provides the driving flow for a plurality of jet pump assemblies. The jet pump assemblies are circumferentially distributed around the core shroud 18. The core shroud 18 (shown in more detail in FIG. 2) in one type of BWR comprises a shroud head flange 18a for supporting the shroud head 28; a circular cylindrical upper shroud wall 18b having a top end welded to shroud head flange 18a; an annular top guide support ring 18c welded to the bottom end of upper shroud wall 18b; a circular cylindrical middle shroud wall comprising three sections 18d, 18e and 18f welded in series, with a top end of section 18d being welded to top guide support ring 18c; and an annular core plate support ring 18g welded to the bottom end of middle shroud wall section 18f and to the top end of a lower shroud wall 18h. The entire shroud is supported by a shroud support 50, which is welded to the bottom of lower shroud wall 18h, and by annular shroud support plate 52, which is welded at its inner diameter to shroud support 50 and at its outer diameter to RPV 10. In the event of a seismic disturbance, it is conceivable that the ground motion will be translated into lateral deflection relative to the reactor pressure vessel of those portions of the shroud located at elevations above shroud support plate 52. Such deflections would normally be limited by acceptably low stresses on the shroud and its weldments. However, if the shroud weld zones have failed due to stress corrosion cracking, there is the risk of misalignment and damage to the core and the control rod components, which would adversely affect control rod insertion and safe shutdown. Stress corrosion cracking in the heat affected zone of any shroud girth seam welds diminishes the structural integrity of shroud 18, which vertically and horizontally supports the core top guide 20 and the shroud head 28. In particular, a cracked shroud increases the risks posed by a loss-of-coolant accident (LOCA). During a LOCA, the loss of coolant from RPV 10 produces a loss of pressure above the shroud head 28 and an increase in pressure inside the shroud 18, i.e., underneath shroud head 28. The result is an increased lifting force on shroud head 28 and on the upper portions of the shroud to which the shroud head is bolted. If the core shroud has fully cracked girth welds, the lifting forces produced during a LOCA could cause the shroud to separate along the areas of cracking, producing undesirable leaking of reactor coolant. A known repair method for vertically restraining a weakened core shroud utilizes tensioned tie rods 54 coupled to the shroud flange 18a and to the shroud support plate 52, as seen in FIG. 2. The lower end of the tie rod/lower spring assembly hooks underneath a clevis pin 60 inserted in a hole machined into gusset plate 58, which plate is in turn welded to shroud support plate 52 and RPV 10. In addition, the shroud 18 is restrained laterally by installation of wishbone springs 56a/56b and 72, which are components of the shroud repair assembly. Referring to FIG. 2, the shroud restraint tie rod/lower spring assembly comprises a tie rod 54 having a circular cross section. A lower end of tie rod 54 is anchored in a threaded bore formed in the end of a spring arm 56a of a lower spring 56. Tie rod 54 extends from the end of spring arm 56a to a position adjacent the outer circumferential surface of the top guide support ring 18c. The upper end of tie rod 54 has a threaded portion. The lower spring 56 is anchored to a gusset plate 58 attached to the shroud support plate 52. The lower spring 56 has a slotted end which straddles gusset plate 58 and forms a clevis hook 56c. The clevis hooks under opposite ends of a clevis pin 60 inserted through a hole machined in the gusset plate 58. Engagement of the slotted end with the gusset plate 58 maintains alignment of lower spring 56 under the action of seismic motion of the shroud, which may be oblique to the spring's radial orientation. The tie rod 54 is supported at its top end by an upper support assembly 62 which hangs on the shroud flange 18a. A pair of notches or slots are machined in the shroud head ring 28a of shroud head 28. The notches are positioned in alignment with a pair of bolted upper support plate segments 64 of upper support assembly 62 when the shroud head 28 is properly seated on the top surface of shroud flange 18a. These notches facilitate coupling of the tie rod/lower spring assembly to the shroud flange. The pair of notches at each tie rod azimuthal position receive respective hook portions 64a of the upper support plates 64. Each hook 64a conforms to the shape of the top surface of shroud flange 18a and the shape of the steam dam 29. The distal end of hook 64a hooks on the inner circumference of shroud dam 29. The upper support plates 64 are connected in parallel by a top support bracket (not shown) and a support block 66 which forms the anchor point for the top of the tie rod. Support block 66 has an unthreaded bore, tapered at both ends, which receives the upper end of tie rod 54. After the upper end of tie rod 54 is passed through the bore, a threaded tensioning nut 70 is screwed onto the upper threaded portion 54a (see FIG. 4) of tie rod 54. As seen in FIG. 2, the assembly comprised of support plates 64 with hooks 64a, support block 66, tie rod 54, lower spring 56, clevis pin 60 and gusset plate 58 form a vertical load path by which the shroud flange 18a is connected to the shroud support plate 52. In the tensioned state, the upper support plates 64 exert a restraining force on the top surface of shroud flange 18a which opposes separation of the shroud 18 at any assumed failed circumferential weld location. Lateral restraint at the elevation of the top guide support ring 18c is provided by an upper spring 72 having a double cantilever "wishbone" design. The end of the radially outer arm of upper spring 72 has an upper contact spacer 74 rotatably mounted thereon which bears against the inner surface of the wall of RPV 10. A spring arm 56a of lower spring 56 laterally supports the shroud 18 at the core plate support ring 18g, against the vessel 10, via a lower contact spacer 76. The top end of spring arm 56a has a threaded bore to provide the attachment for the threaded bottom end 54b (see FIG. 4) of tie rod 54. The member 56d connecting the upper wishbone spring 56a, 56b to clevis hook 56c is offset from the line of action between the lower end of tie rod 54 and clevis pin 60 to provide a vertical spring compliance in the load path to the tie rod. A middle support 80 is preloaded against the vessel wall at assembly by radial interference which bends the tie rod 54, thereby providing improved resistance to vibratory excitation failure of the tie rod. The middle support also provides a lateral motion limit stop for the shroud central shell, in the event of complete failure of its girth welds. To facilitate mounting of the middle support 80, a mid-support ring 82 is secured to the tie rod 54, as shown in FIG. 4. The middle support 80 has a section of an annular recess counterbored in its bottom which form fits on ring 82, thereby preventing lateral shifting of middle support 80 relative to tie rod 54. The middle support 80 is latched to midsupport ring 82 by a wishbone spring latch (not shown), which blocks upward vertical displacement of middle support 80 relative to tie rod 54. During installation of the shroud repair hardware shown in FIG. 2, the tie rod/lower spring assembly comprising tie rod 54 screwed into lower spring 56 is suspended from a cable and lowered into the annulus to the desired elevation. Only after clevis hook 56c has been hooked under clevis pin 60 and the tie rod/lower spring assembly has been braced in the hooked position will the upper support assembly 62 be installed, followed by upper spring 72. As the cable is lowered, the tie rod/lower spring assembly must be guided into the narrow space between adjacent jet pump assemblies. However, in some BWRs this installation site lies below the feedwater sparger, core spray header and core spray downcomer piping, which lie in the path of a descending tie rod suspended from an overhead crane. To protect the feedwater sparger and core spray header from damage due to impact by the descending tie rod/lower spring assembly, which weighs in excess of 1,000 pounds, a cover is hooked onto the feedwater sparger to deflect the tie rod away from the feedwater sparger and core spray header. However, the cover obstructs the cable so that the tie rod/lower spring assembly does not hang plumb from the crane. This makes it difficult to maneuver a suspended tie rod/lower spring assembly into the correct position in the downcomer annulus. In particular, unless appropriate steps are taken, the cover will obstruct the taut cable from becoming oriented vertical and limit radially outward movement of the cable at the point of contact and tie rod/lower spring assembly suspended therefrom. Also the friction between the taut cable and the cover impedes tangential movement of the suspended tie rod/lower spring assembly. As a result, the azimuthal and radial positions of the tie rod/lower spring assembly cannot be controlled by moving the crane to a corresponding position overhead, preventing placement of the suspended tie rod/lower spring assembly at the precise position required for coupling to the gusset plate. SUMMARY OF THE INVENTION The present invention is a strongback for lowering a tie rod into the downcomer annulus of a boiling water reactor during a shroud repair operation. The tie rod strongback is suspended from a cable via a cable adaptor at its upper end. The lower end of the strongback is coupled to a tie rod adaptor, which in turn couples to the top of the tie rod. The strongback is designed to circumvent the piping obstructions so that the tie rod/lower spring assembly is freely suspended from the end of the cable and the cable remains plumb. In accordance with the preferred embodiment of the invention, the upper coupling of the strongback is an apertured plate which can be attached to an apertured clevis of the cable adaptor by means of a first clevis pin, and the lower coupling of the strongback is an apertured clevis which can be attached to an apertured plate of the tie rod adaptor by means of a second clevis pin. The first and second clevis pins are preferable mutually parallel. In this case, a line perpendicular to the clevis pins and intersecting the axes of both clevis pins defines a reference axis, which will be disposed generally collinear with the cable when the cable is plumb and the strongback is suspended from the end of the cable. In other words, when the strongback is freely suspended from the end of a cable which is plumb, the reference axis will be vertical. In accordance with the preferred embodiment of the invention, the strongback is a welded assembly comprising: a plurality of rigid tubes, each tube having a square cross section; a plurality of channels for reinforcing the joints of welded tubes; and the aforementioned upper and lower couplings. In particular, the strongback in accordance with the preferred embodiment comprises mutually parallel first and second rigid linear members which are disposed parallel to the reference axis. The top of the second rigid linear member is connected to the bottom of the first rigid linear member by a relatively obliquely disposed third rigid linear member. The first, second and third rigid linear members lie in a vertical plane which is offset from the reference axis, to allow the strongback to circumvent the core spray downcomer piping. In addition, the first and second rigid linear members are offset from each other to allow the strongback to circumvent the feedwater sparger and the core spray header. The strongback must have a height sufficient to span the distance between a point above the feedwater sparger to a point below the core spray elbow, thereby allowing a shorter cable to be used. Because the cable ends at a point above the piping obstructions and the strongback circumvents the piping obstructions, the tie rod/lower spring assembly can be freely suspended from the cable without the cable or the intermediate supporting hardware bearing against the piping. Thus, the cable stays plumb and the position of the bottom of the tie rod/lower spring assembly relative to the gusset plate, to which the assembly will be anchored, can be freely adjusted by displacing the cable when the tie rod/lower spring assembly reaches its final elevation in the annulus.
051075300	summary	The present invention relates to the control of the shutter of an x-ray diffractometer and more specifically relates to an x-ray diffractometer with a non-magnetic shutter position sensor and indicator. BACKGROUND OF THE INVENTION X-ray diffractometers are known in the art and are used for applications such as directing an x-ray beam toward a crystal to obtain reflection angles of the beam from the crystal for use in studying the crystal. The analysis of a crystal using an x-ray diffractometer can require a significant amount of time with eight hours to three days not being unusual. During the period of experimentation with a crystal, the shutter of the x-ray diffractometer may be opened and closed 10,000 to 15,000times in a 24-hour period. In a conventional x-ray diffractometer, such as a Model No. AFC6, RU200B Series x-ray diffractometer from Rigaku Corporation of Japan, the shutter comprises a rotary controlled shutter element which is rotated between a first closed position and a second open position. When the shutter is open, a path is provided between a radiation source and a target, such as a crystal. In this apparatus, a solenoid is rotated to rotate a shaft which in turn rotate the shutter. A bar magnet is supported on the shaft and is shifted as the shaft rotates between a first position, corresponding to the closed position of the shutter, and a second position, corresponding to the open position of the shutter. As the shaft rotates between the respective first and second positions, reed switches at these positions are activated to provide a shutter position indicating signal. In operation, a computer controller of the Rigaku device causes the solenoid to shift the shutter to a desired position, such as to the second or open position. The computer then receives a position indicating signal from one of the reed switches and compares this signal with the expected position corresponding to the position to which the shutter has been operated by the solenoid in response to the controller. If the expected position does not correspond to the detected position determined from the signals from the reed switches, a shutter error position signal is generated. In the case of a shutter error, the solenoid is operated to close the shutter and the system shuts down. Because of the large number of shutter operations normally required during the analysis of a crystal or during other uses of the x-ray diffractometer, the reed switches tend to wear, with frequent component replacement being required. Also, proper alignment of the replacement reed switches is difficult to attain. Furthermore, as the parts deteriorate through use, false shutter position indicating signals are generated and result in the erroneous shutdown of the equipment. This results in a substantial loss of many hours of experimentation time, particularly when x-ray diffractometers are set up for the automatic running of an experiment overnight or on a weekend with a researcher returning and learning that the experiment has stopped midstream. In addition, sometimes valuable sample crystals are lost due to the instability of these crystals and the fact that these crystals lack the stability simply to restart an experiment which has erroneously been terminated. The inventor has found that the Rigaku system as described above frequently provided false shutter position errors, with errors occurring at least once every three or four days over many periods of operation of the x-ray diffractometer. This problem with accurately controlling and detecting the presence of a shutter under the adverse operating conditions required by an x-ray diffractometer have been present for a number of years. That is, since the Rigaku x-ray diffractometer mentioned above was introduced, the inventor understands that this problem of generating false shutter position signals has plagued users of this device without being solved. The assignee of the present invention first obtained this model of Rigaku x-ray diffractometer in November of 1987. Therefore, a need exists for an improved shutter control mechanism for an x-ray diffractometer designed to overcome these and other problems of the prior art. SUMMARY OF THE INVENTION An x-ray diffractometer directs an x-ray beam toward a target through a shutter. The x-ray diffractometer has a controller for causing the shifting of the shutter between a first closed position, in which the passage of the x-ray beam through the shutter is blocked, and a second open position, in which the passage of the x-ray beam through the shutter is not blocked by the shutter. The controller has an input for receiving a shutter position indicating signal. The controller compares the shutter position corresponding to the shutter position indicating signal with the expected shutter position corresponding to the shutter position to which shutting of the shutter has been caused by the controller. The shutter is caused to be shifted to a closed position in the event the shutter position corresponding to the shutter position indicating signal does not also correspond to or match the expected shutter position. In accordance with the invention, an optical shutter position sensor or detector is mounted to a support in proximity to the shutter for sensing the position of the shutter and for producing the shutter position indicating signal. Such a shutter position sensor is a non-mechanical sensor in that it does not rely upon a mechanical switch, that is one in which mechanical components included in an electrical circuit path move to mechanically open and close the circuit utilized in sensing the shutter position. This type of shutter position sensor electronically produces the shutter position indicating signal which corresponds to the position of the shutter. Although various optical detectors or sensors may be used, including the reflecting optical beam type sensor, a preferred form of the sensor is an interrupting optical beam type sensors. In this specific form of the invention, a mechanism is provided for interrupting a first optical beam when the shutter is in the first closed position and for interrupting a second optical beam when the shutter is in the second open position. The position indicating signal corresponds to the optical beam which is interrupted and thereby indicates the position of the shutter. This mechanism may comprise first and second optical beam breaking elements coupled to the shutter for respectively interrupting the first and second optical beams depending upon the shutter position. Alternatively, the mechanism may comprise a single element, such as an arm mounted to or otherwise coupled to the shutter and movable with the shutter between first and second positions to interrupt the respective first and second optical beams as the shutter is shifted between the first closed position and second open position. This arm may be L-shaped with a flag portion which is disposed between a transmitter and receiver of an optical detector to break a beam being transmitted between the receiver and detector to thereby indicate the shutter position. More specifically, the first and second optical detectors may comprise respective optical isolators each having an optical beam source and an optical beam receiver. The shutter may be of any convenient form and may comprise a rotary shutter operated in response to control signals from a conventional controller. These control signals may be delivered to a rotary solenoid for shifting the shutter between the first closed position and the second open position. It is accordingly one object of the present invention to provide an x-ray diffractometer with an improved controller and more specifically with an improved shutter position indicating mechanism. Another object of the present invention is to provide an x-ray diffractometer which is capable of operating for substantial periods of time without falsely indicating the shutter position, which can cause the termination of an experiment and significant lost time. Still another object of the present invention is to provide an x-ray diffractometer shutter position sensor which is extremely durable. These and other objects, features and advantages of the present invention will become apparent with reference to the following description and drawings.
059638869	description	DETAILED DESCRIPTION OF THE DRAWINGS Referring to FIG. 1, a monitoring arrangement according to the invention is designated generally by reference numeral 10. The arragement 10 monitors the operation of a system 12 which is an electric utility. The utility comprises a network 38 which is divided into regions 36.1 and 36.2. The region 36.1 has stations 34.1 and 34.2 and the region 36.2 has stations 34.3, 34.4 and 34.5. The station 34.1 has objects 32.1, 32.2, and 32.3; the station 34.2 has objects 32.4, 32.5, 32.6 and 32.7; the station 34.3 has objects 32.8 and 32.9; the station 34.4 has objects 32.10, 32.11 and 32.12; and the station 34.5 has objects 32.13 and 32.14. The object 32.1, in turn, is made up of devices 30.1, 30.2, 30.3 and 30.4; the object 32.2 is made up of devices 30.5, 30.6 and 30.7; the object 32.3 is made up of devices 30.8, 30.9, 30.10 and 30.11; the object 32.4 is made up of devices 30.12 and 30.13; the object 32.5 is made up of devices 30.14 and 30.15; the object 32.6 is made up of devices 30.15, 30.16 and 30.17; the object 32.7 is made up of devices 30.18 and 30.19; the object 32.8 is made up of devices 30.20, 30.21, 30.22, 30.23, 30.24 and 30.25; the object 32.9 is made up of devices 30.26, 30.27, 30.28 and 30.29; the object 32.10 is made up of devices 30.30 and 30.31; the object 32.11 is made up of devices 30.32 and 30.33; the object 32.12 is made up of devices 30.34 and 30.35; the object 32.13 is made up of devices 30.36, 30.37, 30.38 and 30.39; and the object 32.14 is made up of devices 30.40, 30.41 and 30.42. Each device 30.1 to 30.42 is monitored by its own monitor 14, in a known manner. The monitors 14 monitor various parameters of the devices 30 and supply appropriate signals, again in known manner, via a transmission means 16, to a central computer 18. This computer 18 processes the signals that it receives and determines when any signal attains an abnormal value. If any parameter for any device 30 does acquire an abnormal value, the parameter, its value, the device and the time are stored in a memory unit 20 to create a database. Further, the various parameters are divided into different categories, being health, main protection, backup protection and information. The number of parameters in each category for each device that acquire an abnormal value are summed and also stored in the memory unit 20. The various categories are upwardly summed, as explained below, for each category, for each object 32, each station 34, each region 36 and the network 38 as a whole; and stored in the memory unit 20. Still further, as explained below, the computer 18 generates and supplies appropriate signals to a display unit 22 which provides a display 60 such as that shown in FIG. 4. In order to explain the pyramidal structure further, the grouping of an electric utility is explained as follows: At the lowest level are the individual devices 30 that form the system, such as breakers, transformers and isolators. When the devices 30 are grouped together they form the electrical objects 32 such as feeder bays, busbars, reactor bays, capacitor bays, transformer bays, etc. Grouping the objects 32 together creates the substations or power generating stations 34. Grouping the stations 34 together forms the region 36 of the network 38. Grouping the regions 36 together forms the network 38. In regard to the categories, as indicated above, they relate to the health of the devices 30, main protection, backup protection and information. Thus, any parameter which indicates that a condition exists on or associated with the device 30 that could prevent it being reinstated safely is classed in the health category. A parameter which is associated with primary protection and which indicates that primary protection has activated is classed in the main protection category. A parameter associated with secondary protection is classed in the backup protection category. Any other non-operation-critical information is classed in the information category. The number of abnormal conditions may be upwardly summed. Referring now to FIG. 2, the pyramidal structure of the electric utility is shown. The structure denotes the utility in a notional representative form. It will be seen that the structure has five levels. A bottom-most, device level 42 represents the individual devices 30 which make up the electric utility. The second level 44 is representative of the electrical objects 32. The next level 46 represents the stations 34. Grouping the stations 34 together provides the regions 36. Finally, the upper-most level is the network 38. As indicated above, various parameters associated with each device (and which vary from one device type to another) are monitored. Also, as indicated above, the parameters are divided into four categories--Health, Main protection, Backup protection and Information. Various parameters for various devices, and the category in which they are allocated are as follows: ______________________________________ 1. GENERATOR HEALTH CATEGORY General alarm Alarm/normal Emergency shutdown Progress/inactive Generator start Not ready/idle Synchronised start Not ready/idle INFORMATION CATEGORY Emergency trip On/off Remote control Sequence start Auto/remote Shutdown Yes/no Status Start/normal Guide vane mode Auto/manual 2. TRANSFORMER HEALTH SF6 non-urgent Alarm/normal SF6 urgent Alarm/normal Scald supervisory Alarm/normal DC supervision Alarm/normal Fire Alarm/normal Bus Zone DC Fail/normal MAIN Bus strip Operated/normal Bus zone Operated/normal Auto U/F control Failed/normal INFORMATION Maximum generation Selected/off Emergency generation Selected/off Maximum Generation Reset/initiated Emergency generation Reset/initiated 3. A DAM HEALTH Low water level Trip/normal BACKUP Supply dam #1 level Trip/normal Supply dam #2 level Trip/normal INFORMATION High water Trip/normal ______________________________________ The manner in which the parameters are monitored are well known to persons skilled in the control of electric utilities and do not form any part of this invention. The manner in which the parameters are upwardly summed is illustrated in FIG. 3 using "diamond-shaped" icons 52 to indicated each category. Thus, the parameters for all the devices 30 in the system are monitored and when any parameter attains an abnormal value the number for the category in question is increased by one. Similarly, if a particular parameter had an abnormal value which then reverted to a normal value, then the number in the category in question for the device in question is decreased by one. As indicated above, there are a number of objects 32 in the object level. Each object 32 is made up of one or more of the devices 30. The number of abnormal parameters in each category for each device 30 associated with a particular object are summed to provide a number for the category in question for the object 32 in question. Thus, for example, if a particular object 32 is made up of four devices 30.1, 30.2, 30.3 and 30.4 and these devices have the following numbers of abnormal parameters in the four categories: ______________________________________ Number of Number of Number of abnormal abnormal Number of abnormal parameters parameters abnormal parameters in main in backup parameters in health protection protection in information category category category category ______________________________________ Device 5 3 4 6 30.1 Device 2 4 5 2 30.2 Device 1 2 0 3 30.3 Device 3 5 6 1 30.4 Total for 11 14 15 12 object 32 ______________________________________ Thus, at the object level, the object 32 will have icons 52, 54, 56 and 58 for each category with the numbers "11", "14", "15" and "12" respectively, therein. As shown, the icons are diamond-shaped. Similarly, at the station level there are a number of stations 34, each station being formed from one or more of the objects 32 in the object level. Again, the number of abnormal parameters in each category for each object 32 forming a particular station 34 are summed to provide the number of abnormal parameters in each category for that station. This process is repeated further upwardly to provide the number of abnormal parameters in each category for each region 36 at the region level and then for the network 38 itself, at the very top of the pyramidal structure. Referring now to FIG. 4, an example of a display that is provided is designated generally by reference numeral 22. The display 22 has two windows, a main work area 60 and a filtering control panel 62. A graphical representation of a chosen part of the system is displayed in the work area 60. In the figure, a sub-station 64 is shown. The various components, or objects 32 comprising the sub-station are represented in known manner. The statuses of the various objects 32, as determined by the parameters of each object are indicated by icons 52, 54, 56 and 58 which are (as discussed above) diamond-shaped with the different categories being indicated by icons of different colours. Thus, the main protection category is designated by a cyan icon; the back-up protection category by a green icon, the health category by a yellow icon; and the information category by a magenta icon. In the control panel 62, there are three groups of symbols 66, 68 and 70. The symbols 66 are for different types of components, the symbols 68 are for different voltage levels, and the symbols 70 are for the different categories of parameters. Thus, there are symbols 66 for the following types of components: generator 66.1; feeder 66.2; bus 66.3; coupler 66.4; transformer 66.5; load 66.6; reactor 66.7 and capacitor 66.8. Similarly, there are symbols 68 for the various voltage levels as follows. 765 KV--68.1; 400 KV--68.2; 275 KV--68.3; 220 KV--68.4; 132 KV--68.5 and 88 KV--68.6. Similarly, there are four symbols 70 for the categories of parameters, viz; main category 70.1; backup category 70.2; health category 70.3; and information category 70.4. Further, in the control panel 62 there are a clear button 72 and a filter button 74. If the filter button 74 is activated, then symbols 66, 68 and 70 that have been selected are given effect and appropriate portions of the graphical representation 64 in the work area 60 greyed out as is explained below. Activation of the clear button 72 removes the greying out and resets the procedure. As shown in the representation 64, there are generators 76, feeders 78, busses 80, couplers 82 and transformers 84. There are no loads, reactors or capacitors in the sub-station displayed in the work area 60. Thus, the symbols 66.1 to 66.5 are normally displayed, whereas the symbols 66.6, 66.7 and 66.8 are greyed out. Similarly, the sub-station has 400 KV and 88 KV voltage levels. Thus, the symbols 68.2 and 68.6 are normally displayed, with the symbols 68.1, 68.3, 68.4 and 68.5 being greyed out. Data is also displayed, as indicated at 76. As indicated by ticks in the blocks associated with the symbols 66, the symbols 66.1, 66.2, 66.4 and 66.5 have been selected. Thus, the graphical representations for the generators 76, feeders 78, couplers 82 and transformers 84 are shown normally. As the symbol 66.3 has been rejected, as indicated by a cross in the relevant block, the busses 80 are shown in a greyed out way. As both possible voltage levels have been selected, there are ticks in the boxes associated with symbols 68.2 and 68.4. Further, as all four parameter categories have been selected, there are ticks in the four boxes associated with the symbols 70. As all four parameter categories have been selected, icons for all the categories will be indicated for all the objects, except the busses, as there have been rejected. Thus, the icons 52, 54 and 58 are displayed. No icon 56 is displayed as none of the selected objects has an abnormal backup parameter. It will be appreciated that the symbols 66, 68 and 70 are selected by a control operator. In use, the operator will choose which part of the system to display in the work area 60 and give an appropriate instruction. The computer 18 will provide the appropriate signals and the appropriate graphical representation will be displayed. Depending on the part of the system that has been chosen, the relevant symbols 66 and 68 will be greyed out. The operator then selects which symbols 66, 68 and 70 he wants and activates them by means of the pointing device and activates the filter button 74. The computer then greys out the relevant portions of the representation. If the operator wishes to change his selection, he activates the clear button 72 by means of the pointing device. It will accordingly be appreciated that the operator can easily and quickly monitor and understand the condition or state of the utility network or any particular component thereof.
041682432	claims	1. The method of solidifying radioactive waste material for transport and long term storage, comprising: A. providing a mixture of radioactive waste material and water with said water being in an amount sufficient to meet a desired low hazard radiation classification when said mixture is solidified with urea-formaldehyde; B. blending said mixture with a syrup, comprising an aqueous suspension of urea-formaldehyde in a partially polymerized state in an amount sufficient to solidify substantially all of the water present; C. adding an acidic curing agent capable of promoting polymerization of said urea-formaldehyde in an amount sufficient to solidify said urea-formaldehyde in said mixture; D. placing the resulting mixture in a storage container substantially as said curing agent is added; and E. allowing said resulting mixture to gel and set in said container whereby a solid mass of the resin is obtained with the water and the radioactive components of said resulting mixture distributed therein. A. transporting a liquid containing a setting agent in the form of a syrup comprising an aqueous suspension of urea-formaldehyde in a partially polymerized state to a reactor site in a supply tank; B. pumping said setting agent at a controlled rate of flow from said tank to a blending chamber; C. pumping waste liquids, containing water and radioactive material from the reactor, to said blending chamber at a controlled rate of flow proportioned to the rate of flow of said setting agent to provide a desired quantity ratio having an amount of urea-formaldehyde sufficient to solidify substantially all of the water present; D. blending said waste liquids with said syrup in said blending chamber; E. delivering the blended liquid mixture from said blending chamber to a receiving tank similar to said supply tank; F. pumping an acidic liquid curing agent capable of promoting polymerization of said urea-formaldehyde in an amount sufficient to solidify said urea-formaldehyde in said mixture to interact with said liquid mixture within said receiving tank so as to cause said liquid mixture to solidify to a desired hardness; G. allowing said resulting mixture to gel and set in said container whereby a solid mass of the resin is obtained with the water and the radioactive components of said resulting mixture distributed therein; H. shielding the filled receiving tank against unwanted radioactive emission; and I. transporting the shielded receiving tank to a disposal site. A. intermixing such waste liquid with a liquid containing a setting agent in the form of a syrup comprising an aqueous suspension of urea-formaldehyde in a partially polymerized state capable of solidifying said waste liquid into a free standing hardened mass upon mixing with a curing agent; B. adding an acidic curing agent capable of promoting polymerization of said urea-formaldehyde in an amount sufficient to solidify substantially all of the water present in said mixture; C. placing the liquid mixture in a storage container substantially as said curing agent is added; D. positioning non-liquid radioactive material having a higher level of radioactivity than said liquid mixture in the central area of said container prior to and during solidification of said liquid mixture; and E. allowing said liquid mixture to gel and set in said container in surrounding relation to said material having a higher level of radioactivity whereby a solid mass of the resin is obtained with the water and the radioactive components of said liquid mixture distributed therein. 2. The method of claim 1 and in which said curing agent is intermixed with said blended syrup and radioactive waste material and water as they enter said container, and the resulting mixture in said container is agitated until it gels so as to distribute the radioactive waste evenly through said solid mass. 3. The method of claim 2 and wherein said container and the solid mass of urea-formaldehyde and radioactive waste material and water contained therein are buried in the earth for disposal. 4. The method of claim 3 and in which said container is shielded to prevent unwanted radioactive emissions to the surrounding environment during filling of said container, and said shielded container is thereafter transported to the burial site. 5. The method of claim 1 and wherein said radioactive waste material initially comprises a slurry of particulate solids in water, and a portion of said water is removed to provide said mixture of radioactive waste material in an amount sufficient to meet a desired low hazard radiation classification when solidified with urea-formaldehyde. 6. The method of claim 1 and wherein said radioactive waste material initially comprises a slurry of radioactive particulate solids in water, said particulate solids are dewatered to a damp state, and water thereafter is added to the dewatered particulate solids to provide said mixture of radioactive waste material in an amount sufficient to meet a desired low hazard radiation classification when solidified with urea-formaldehyde. 7. The method of claim 6 and wherein said radioactive particulate solids comprise spent ion exchange resin beads from the cooling system of a nuclear reactor. 8. The method of claim 6 and wherein said dewatering takes place in said container. 9. The method of claim 6 and wherein dewatered radioactive particulate solids are added to said container before said resulting mixture. 10. The method of claim 9 and wherein said dewatered radioactive particulate solids are confined centrally of said container so as to be surrounded and encapsulated by said resulting mixture as it gels and sets. 11. The method of claim 10 and wherein said radioactive particulate solids comprise spent ion exchange resin beads from the cooling system of a nuclear reactor. 12. The method of claim 10 and wherein said dewatered radioactive particulate solids confined centrally of said container have an average specific level of radioactivity higher than the surrounding solid mass whereby said solid mass provides a radiation shielding effect. 13. The method of claim 1 and wherein additional non-radioactive filler material is added to said mixture prior to introduction thereof into said container so as to reduce the low hazard radiation classification of said solid mass. 14. The method of claim 1 and wherein the proportion of said urea-formaldehyde to said curing agent is controlled to provide a desired curing time and hardening of said solid mass. 15. The method of claim 14 and wherein the curing time and hardening of said solid mass is further controlled by adding an inhibiting agent to said mixture, said inhibiting agent comprising ethylenediamine tetraacetic acid, disodium. 16. The method of claim 14 and wherein the curing time and hardening of said solid mass is further controlled by heating said mixture to speed up further polymerization. 17. The method of claim 1 and wherein additional amounts of said syrup and water and curing agent are mixed together and added to said container after said resulting mixture has been allowed to gel and set so as to fill up unoccupied areas of said container and take up any free water present therein. 18. The method of solidifying radioactive waste material for transport and long term storage, comprising: 19. The method of claim 18 and wherein said pumping of said waste liquids and said syrup and curing agent is accomplished by individual positive displacement pumps whereby the rate of flow of each is determined by the speed at which each corresponding pump is driven, and said pumps are driven at individually variable speeds for controlling the relative proportions of said waste liquids and said setting and curing agents being delivered to said receiving tank. 20. The method of claim 19 and wherein said individual pumps block flow of the material they pump when not being driven so as to prevent cross-contamination and unwanted solidification of said liquid mixture prior to entry into said receiving tank. 21. The method of claim 18 and wherein a water slurry of radioactive spent ion exchange resin beads is first pumped into said receiving tank, said resin beads are dewatered by removing the water component of said water slurry, and said liquid mixture and curing agent is then pumped into said receiving tank to surround and encapsulate said dewatered resin beads. 22. The method of claim 21 and wherein said liquid mixture and curing agent and dewatered resin beads are stirred together in said receiving tank as said liquid mixture solidifies. 23. The method of claim 18 and wherein additional radioactive solid materials are supported centrally of said receiving tank as said liquid mixture solidifies. 24. The method of claim 18 and wherein said radioactive solid materials include filter components. 25. The method of claim 18 and wherein a limited quantity of flush water is pumped through the system as filling of said receiving tank is completed to prevent unwanted solidification of said setting agent in the system. 26. A method for disposing of waste liquid containing water and radioactive material, comprising: 27. The method of claim 26 and wherein said materials having a higher level of radioactivity are retained within an enclosure mounted centrally of said container during filling of the container and gelling and setting of said liquid mixture. 28. The method of claim 27 and wherein said holding enclosure comprises a perforated basket, and said radioactive materials comprise a slurry of water and of particulate solids incapable of passing through the perforations in said basket whereby the liquid phase of said slurry falls from said basket through said perforations leaving said particulate solids in said basket, and said liquid phase is pumped from said container before said resulting mixture of blended syrup and radiation material and curing agent are placed in said container. 29. The method of claim 26 and wherein the proportions of said urea-formaldehyde and curing agent are controlled to delay gelling and setting of said liquid mixture until after said liquid mixture has surrounded said non-liquid radioactive materials positioned in the central area of said container. 30. The method of claim 26 and wherein additional non-radioactive filler material is mixed with said liquid mixture to dilute the hardened solid mass to desired Lowest Activity counts and provide additional shielding for said non-liquid radioactive material positioned in the central area of said container.
048662801	claims	1. An objective lens of an electron beam apparatus in which an electron beam emitted from an electron gun is converged onto a specimen, the reflected electron from the specimen or the secondary electron emitted therefrom is detected, and a fine pattern on the specimen is measured, said lens comprising: a magnetic circuit structure including an upper magnetic pole member having an opening to transmit the electron beam to be converged which was emitted from said electron gun, a lower magnetic pole member disposed so as to face said upper magnetic pole member, and a magnetic path member to connect the outer peripheral edges of the upper and lower magnetic pole members; a coil, arranged in a part of said magnetic circuit structure, for generating magnetic fluxes passing through said upper and lower magnetic pole members, said magnetic path member, and the space between said opening edge and the lower magnetic pole member when said coil is excited; and moving means which is disposed on the surface of the lower magnetic pole member opposite to the upper magnetic pole member and is movable on the plane substantially perpendicular to said electron beam in a space enclosed by said magnetic circuit structure in the state in which the specimen is put on the upper surface of said moving means. 2. An objective lens according to claim 1, further having a projecting portion in the portion of said lower magnetic pole member opposite to the opening of said upper magnetic pole member, said projecting portion projecting toward the side of said opening. 3. An objective lens according to claim 1, wherein a part of the side wall of said magnetic circuit structure has an opening portion and said specimen is disposed onto said moving means through said opening portion. 4. An objective lens according to claim 1, wherein said upper and lower magnetic pole members of said magnetic circuit structure are arranged so as to enable movement of at least one of said upper and lower magnetic pole members in the direction of the electron beam. 5. An objective lens according to claim 1, wherein said moving means has a first moving member which is movable on the upper surface of said lower magnetic pole member in the directions along one axis and a second moving member which is mounted on said first moving member and is movable in the direction along the axis perpendicular to said axis, and said specimen is disposed on said second moving member. 6. An objective lens according to claim 1, wherein said upper magnetic pole member, said lower magnetic pole member and said magnetic path member are disposed so as to delimit a chamber in which the specimen is received and which provides a magnetic shielding effect with respect to the electron beam.
050892207	claims	1. A fuel assembly in the form of an elongated multi-corner channel having a wall, said channel being connected to a coolant intended to traverse the channel in a downstream direction, a bundle of similarly elongated fuel rods arranged in the channel and retained by a plurality of spacers placed along the bundle, each one of said spacers comprising a number of cells surrounded by an outer frame in the form of a band placed on edge, said band arranged to fit closely in the channel, said band being provided with a number of windows, wherein in at least certain of said windows a deflection fin is arranged fixed to an upstream edge of each respective window, each said fin extending in the direction of flow from said edge and including a portion which extends in a direction towards a centre of the channel in order to divert coolant flowing along an inner wall-of the channel in a direction towards the centre of the channel. 2. A fuel assembly according to claim 1, wherein an upstream outer portion of the band up to a middle portion on the band around the band extends towards the center of the spacer in relation to said middle portion to form a pocket between said outer portion and the inner wall of the channel, and wherein openings are provided in the band on the upstream side of each respective window to provide fluid communication between the pocket and an interior of the spacer. 3. A fuel assembly according to claim 1, wherein a downstream end of each fin is joined by means of a supporting band to a downstream edge of each corresponding window. 4. A fuel assembly which comprises a wall that defines an elongated, multi-cornered channel through which coolant can flow from an upstream end to a downstream end, a bundle of elongated fuel rods positioned in said channel, and a plurality of spacer means positioned at separated locations along said bundle of fuel rods, each of said spacer means comprising an elongated outer band located adjacent said wall, means defining a plurality of cells within the outer band and a center line, said elongated outer band including a plurality of window through which coolant passing in said channel adjacent said wall can flow, said window having upstream edges, and fins connected to said upstream edges of at least some of said window, said fins including portions which extend inwardly of said wall and in said downstream direction so as to deflect coolant flowing in said downstream direction inwardly of said wall and towards said center line.
039909417	description	DETAILED DESCRIPTION OF THE INVENTION Having reference to the above drawing, the pressurized-water reactor installation involved may have a power rating in the area of 1,200 MWe. Therefore, the pressure vessel 1 should be provided with very effective rupture protection. Consequently, the pressure vessel 1 is made from thick-walled steel annular sections welded edge-to-edge to form a vertical cylindrical vessel having its top closed by a removable head 2 overlayed by reinforcing cover 4 held down via its periphery by an intercept ring 5 firmly secured when the pressure vessel thermally expands vertically, by self-locking hooks 6 pivoted at 7, the biological shield forming the reactor cavity or pit 10 by its concrete wall 12 and by its steel reinforced concrete wall 12 to the top of which the hook pivots 7 are anchored, vertical steel bars 13 extending through the concrete for vertical reinforcement. The annular space between the concrete wall and the wall of the vessel 1 is shown at 15 while the heat insulating and pressure-resistant concrete wall formed by the large cast blocks is shown at 16, this layer directly contacting the outside of the pressure vessel wall when the latter is thermally expanded radially by operation of the reactor. This concrete layer 16 may occupy about two-thirds of the width or thickness of the annular space 15. The steel beams previously described are shown at 17 as forming via their abutting flange edges what is substantially a cylinder made of steel. In this instance, I-beam shapes are used with their flanges 18 against which the heat insulating layer 16 presses during reactor operation, forming a circumferentially continuous steel wall transmitting compression to the other flanges of the beams which press against the concrete wall of the biological shield to form there also what is, as a practical matter, another continuous steel wall. When the reactor is in operation, the heat-insulating layer and beams are under compression in the radial direction of the vessel 1 with the concrete wall of the biological shield providing the reaction, the pressure vessel thus being provided with zero-travel restraint. The parts are proportioned so that when the reactor is cold and thermally contracted, the blocks forming the heat-insulating layer can be pulled upwardly to form a space for external pressure wall inspection. A sheet steel skin 19 is shown as being fastened to the innermost flanges of the beams so that the air coolant ducts 22 formed between the beam webs are provided with the sealing previously referred to. The coolant may be introduced via a duct 24 to an annular manifold space 25 extending peripherally around and open to the bottom ends of the vertical air coolant ducts 22, the air rising upwardly in the direction of the arrow 26 adjacent to the coolant nozzles 27 which radiate from the upper end of the vessel 1, baffles 28 diverting a portion of the upwardly flowing coolant, as by annular ducts 28, so that some of the air coolant flows circumferentially around the nozzles and outwardly in their axial directions, the balance of the air coolant leaving via the tops of the ducts 22 providing the advantage of cooling the steel hooks 6. To provide for a coolant flow, the steel support ring 14, on which the bottom of the pressure vessel is supported against downward motion, is provided with radial ducts 14a. A hemispherical layer 32 of heat-insulating concrete is positioned against the hemispherical bottom 30 of the pressure vessel 1, and is supported via steel beams 33 by the bottom of the biological shield cavity, these beams extending radially and necessarily being curved, but to some extent in the manner described before, providing coolant ducts which may be supplied with air via a duct 34 extending to the center of the hemispherical nest of steel beams.
	summary
	abstract	A fuel assembly is charged in a reactor core of a nuclear reactor using a liquid metal as a coolant, and includes a wrapper tube storing a plurality of fuel pins and including an entrance nozzle for introducing the coolant and an operation handling head, grids disposed in the wrapper tube to support the fuel pins in the radial direction of the wrapper tube, liner tubes inserted in the wrapper tube to fixedly hold the respective grids in the axial direction of the wrapper tube, and a fixing device for fixing the grids and the liner tubes in the radial direction of the wrapper tube.
	abstract	A device and method for the heating of plasma by resonance using Halbach transformers for magnetic field modulation. Forming the Halbach transformers of heating to the primary magnetic field coils of confinement in a typical ring cusp confinement device configuration may reduce high-voltage breakdown along coil supports. By heating the plasma transverse to the confinement field a greater number of particle species may be retained. The primary confinement field coil support is placed outboard of the plasma cusp region by extending lobed flanges from the plates of Bitter-type primary electromagnetic field coils into the outboard region and placing the holes for the coil supports through these flanges. This arrangement of coil and flange moves plasma bombardment from the cusp region to the outboard region thus moving impurity generation by coil support bombardment from the cusp region to an outer radius where impurity effects are less detrimental.
049967010	description	FIG. 1 shows diagrammatically an example of a device for slit radiography, comprising an X-ray source 1, a slit diaphragm 2 placed in front of the X-ray source, and an X-ray screen 3. The slit diaphragm 2 transmits a fan-shaped X-ray beam 4 having a relatively low thickness. In operation, the X-ray source and/or the slit diaphragm are moved in a manner such that the X-ray beam 4 scans the X-ray detector 3. For this purpose, for example, the X-ray source may be swung together with the slit diaphragm about an axis extending transversely to the plane of the drawing through the X-ray focus f as indicated by an arrow 5. If a body 6 to be irradiated is situated between the X-ray source and the X-ray detector, an X-ray photograph can be taken in this manner of (a part of) the body 6. Attention is drawn to the fact that, instead of a stationary X-ray detector, a strip-like X-ray detector may also be used in the manner described in Dutch patent application No. 8303156. In order to be able to influence the amount of X-ray radiation transmitted through the slit diaphragm per sector of the fan-shaped X-ray beam to take an equalized X-ray photograph, controllable attenuation elements 7 are present which act in conjunction with the slit diaphragm and which act as beam sector modulators. The attenuation elements may be constructed in various manners, such as described, for example, in Dutch patent application No. 8400845. In the example shown in FIG. 1, the attenuation elements are tongue-shaped and the free ends of the tongues can be swung to a greater or lesser extent into the X-ray beam under the influence of suitable control signals. The attenuation elements may, however, also be of the slider type as also described in Dutch patent application No. 8400845. To generate the control signals needed for the attenuation elements, there is a detector present which is situated beyond the body 6 to be irradiated and which detects the radiation transmitted by the body 6 for each sector of the X-ray beam and delivers corresponding electrical signals. The detector may consist of a row of light detectors which are situated behind the X-ray screen at the height of the incident beam and which detect the amount of light generated by the X-ray screen 3 under the influence of the incident X-ray radiation. It is also possible to detect the X-ray radiation transmitted through the X-ray screen 3. The detector may also be situated in front of the X-ray screen and may then consist for example of an oblong dosimeter such as described, for example, in the applicant's earlier Dutch patent applications No. 8503152 and 8503153. Such a dosimeter is diagrammatically indicated in FIG. 1 at 8 and is moved synchronously together with the scanning X-ray beam as is indicated by an arrow 9. The signals originating from the dosimeter are fed via an electrical conductor 10 to a control circuit 11 which forms the control signals for the attenuation elements. In the technique described hitherto, a constant spectrum and a constant intensity of the X-ray beam delivered by the X-ray source is assumed before it is influenced by the attenuation elements. According to the invention, on the other hand, the radiation flux and/or the hardness of the X-ray beam is modulated in a predetermined fixed manner, while a sectorwise controlling of the X-ray beam also takes place in addition by means of the attenuation elements. As will emerge below, it is possible, in this manner, for a simpler control of the attenuation elements to be sufficient, while, in certain embodiments of the invention, the high-voltage supply of the X-ray tube can also be simpler. The predetermined fixed influencing of the X-ray beam can be achieved in various manners. According to a first exemplary embodiment of the invention, the high voltage of the X-ray tube is modulated with a fixed ripple voltage. If a ripple voltage with the mains frequency (50 Hz or 60 Hz) is used, the high-voltage supply for the X-ray tube can be relatively cheap because no measures are then necessary to eliminate the ripple in the supply voltage which is always present and is caused by the mains frequency. FIG. 2 shows an example of a modulated supply voltage V.sub.B for the X-ray tube. Such a voltage can be obtained in a simple manner by full-wave rectification of a normal sinusoidal alternating voltage. The value of the supply voltage of the X-ray tube determines the hardness of the X-ray radiation and, in particular, in such a manner that the hardness of the X-ray radiation increases with a higher value of V.sub.B. An X-ray tube energized with a supply voltage of the type shown, therefore, delivers an X-ray beam whose hardness increases cyclically in synchronism with the supply voltage from a minimum value to a maximum value and then again decreases to the minimum value. In combination with the varying supply voltage, the position of the attenuation elements is controlled in a manner such that each attenuation element is in the open position during the intervals o when the tube voltage is low, while in the intervening intervals d, the attenuation elements are in principle in the closed position so that the X-ray beam is essentially intercepted in said intervals. FIG. 3 illustrates the variation, achieved in this manner, in the position of one of the attenuation elements between the fully closed position and the fully open position. The other attenuation elements are controlled in synchronism in the same manner. The attenuation elements, therefore, transmit in principle only relatively soft radiation. In order to obtain the desired sectorwise influencing of the X-ray beam as a function of the radiation transmitted in the sector concerned through the irradiated body, the intensity of the radiation transmitted by the irradiated body is measured during the intervals o, for example by means of the dosimeter 8, in each sector. For those sectors in which a predetermined minimum intensity is not reached, the closing of the attenuation elements concerned is prevented during the subsequent interval. In this manner, harder radiation is transmitted in those sectors in which parts of the irradiated body which are less transparent to X-ray radiation are situated. In FIG. 3, this is indicated diagrammatically by a broken line for the interval d'. If the predetermined minimum radiation intensity is again reached or exceeded in a certain sector during a subsequent interval o, the associated attenuation element is again closed in the interval d subsequent thereto. Since the scanning X-ray beam has a certain thickness which may be, for example, approximately 4 cm at the position of the X-ray detector, the brightness of each image point of the X-ray photograph is determined by integration of the instantaneous brightness values which occur during the passage of the scanning beam over the image point concerned. As a result thereof, excessively sharp light-dark transitions are avoided in the final X-ray photograph in the scanning direction. A contribution is also made to this by the fact that in practice the opening and closing of the attenuation elements requires some time. This control of the attenuation elements is very simple since the latter only have to be brought to two discrete positions (fully open or fully closed) and since it is only necessary to detect whether the radiation transmitted by the irradiated body exceeds or does not exceed a predetermined value of intensity. The manner described in the foregoing of controlling the attenuation elements may, if desired, be refined by making use of more than two possible discrete positions of the attenuation elements. Thus, for example, a half-closed intermediate position may be defined in which an attenuation element is brought if the value of intensity of the radiation transmitted by the irradiated body in the associated sector lies between two predetermined values. Such an intermediate position is indicated diagrammatically with a broken line at d". It is also possible to use several intermediate positions or even a continuous variation of the position. The manner described in the foregoing of controlling the attenuation elements could be termed an amplitude control because the attenuation elements are brought to one of a number of possible discrete positions during predetermined time intervals. As an alternative it is possible to use a phase control in which each attenuation element alternately opens and closes, but in which the point of time at which this takes place may be displaced with respect to the modulated high voltage of the X-ray tube or the X-ray beam modulated in a fixed way in another manner. FIG. 4 illustrates the principle of the phase control system. FIG. 4 shows, in the same manner as FIG. 2, the fixed modulation of the X-ray beam obtained by modulation of the high voltage of the X-ray tube. In addition, in FIG. 4 intervals are indicated by way of example for a single attenuation element during which the attenuation element is completely opened or completely closed. During the intervals o.sub.1 and o.sub.2, the attenuation element is opened during intervals in which the high-voltage of the X-ray tube is relatively low, just as in the manner of control previously described. If the radiation transmitted by the irradiated body in the sector associated with the attenuation element concerned has an intensity below a predetermined value during the second "open" interval o.sub.2, the beginning of the third "open" interval o.sub.3 is advanced by a predetermined time, as shown in FIG. 4. In the sector of the X-ray beam concerned, the body to be irradiated received harder X-ray radiation as a result of this. In the situation shown in FIG. 4, both the beginning and the end of the interval o.sub.3 have been advanced, and the length of the interval is unchanged. In order to be able to determine whether the subsequent interval should also be advanced, the measurement of the radiation transmitted by the irradiated body in the sector of the X-ray beam concerned should also take place during the advanced "open" interval. To do this, the procedure may be such that, if the intensity of the radiation transmitted by the irradiated body in said sector during the advanced interval does not exceed a predetermined maximum value, the subsequent interval is also advanced in the same manner, as indicated in FIG. 4 for the interval o.sub.4. As an alternative, it is also possible to advance only the starting point of an "open" interval by a predetermined time as soon as the radiation transmitted by the body in the associated sector of the X-ray beam fails to reach the predetermined value of intensity in a preceding "open" interval, but to leave the end point of the interval concerned unchanged. As a result the interval, therefore, becomes longer but still contains the complete original "open" interval as well. All this is shown in FIG. 5. In FIG. 5 the starting point of interval o.sub.13 has been advanced so that an extended open interval o.sub.13 ' is produced, during which harder radiation is transmitted in addition to the relatively soft radiation transmitted by the attenuation element concerned in the prceding intervals. The extended interval contains also the complete unextended interval o.sub.13. The measurement of the intensity of the radiation transmitted through the irradiated body in the sector concerned can still, therefore, take place in the "original" interval o.sub.13. If the measured value of intensity then again fails to reach the predetermined threshold value, the starting point of the subsequent "open" interval is also advanced. The simplest form of the phase control described could be based on only two different positions of the "open" intervals with respect to the curve representing the fixed modulation of the X-ray beam. If, as shown in FIG. 6, a peak of the modulation curve is regarded in each case as a complete cycle which contains a phase trajectory of 360.degree., the control circuit could, for example, be constructed in a manner such that the "open" interval of an attenuation element extends either from -90.degree. (=270.degree.) to +90.degree., or from 180.degree. to 360.degree. (by analogy with FIG. 4), or such that the "open" interval always ends at 90.degree. but the starting point is either at -90.degree. (=270.degree.) or at 180.degree. (with reference to FIG. 5). It is obviously also possible to choose a different position for the advanced "open" interval. A refined phase control system may be obtained by choosing a number of different discrete threshold values of the radiation intensity measured behind the body irradiated and, consequently, corresponding fixed phase trajectories for the "open" intervals of the attenuation elements. The most precise control is obtained if the position of at least the starting point of the open intervals can be varied continuously as a direct function of the instantaneous value of the measured intensity of the radiation transmitted by the irradiated body. Attention is drawn to the fact that, as follows directly from FIGS. 4 to 6 incl., phase control can be achieved with the same effect by delaying the "open" interval, or at least the endpoint thereof. Use is made of this principle in one embodiment of the invention to be described in yet further detail below. In the Dutch patent application No. 8400845 mentioned earlier, attenuation elements acting as beam sector modulators are described which are tongue-shaped or constructed as slides and which can take up any position between a position exposing the slit of the slit diaphragm completely and covering the slit completely under influence of the control signals. Such attenuation elements may also readily be used within the scope of the present invention. However, because the attenuation elements are opened and closed at a constant frequency in the phase control system described above, only the point of time of opening and/or closing being varied, use may be made of a continuously rotating spindle provided with attenuation elements. All this is shown diagrammatically in FIG. 7. FIG. 7 shows the slit S of the slit diaphragm of a slit radiography device. In front of the slit diaphragm there is placed a spindle 20 which can be made to rotate by means not shown. On the spindle 20 there are placed next to each other wheels of a blade type, only one of which, indicated by 21, is shown. The blade wheels together occupy the entire length of the slit S. The blades 22 of the blade wheels consist of material which attenuates or blocks X-ray radiation and extend to a distance from the spindle 20 placed somewhat higher or lower than the slit S, such that during the rotation of the spindle each blade in each case covers the section of the slit S situated opposite the blade wheel for a short time, as can be seen in FIG. 8. The dimensions of the blades, distribution of the blades over the circumference of the blade wheel and the number of blades are chosen in a manner such that on rotating the spindle at a fixed rotary speed matched to the frequency or the fixed modulation of the X-ray beam 4, the slit is cyclically covered or exposed by the blades. In order to be able to implement the required phase control, it must be possible to vary the position of each blade wheel separately with respect to the spindle 20 at least temporarily. For this purpose, the blade wheels are mounted in a slipping or sprung manner on the spindle and each blade wheel is provided with an electrically energizable brake. When the brake of a blade wheel is energized, the angular position of said blade wheel changes with respect to the spindle 20 so that the next blade begins to intercept the X-ray beam later and the phase of the open intervals changes with respect to the fixed modulation of the X-ray beam. An example of a brake for a blade wheel is shown diagrammatically in FIG. 9. The brake comprises a small brake block 23 which is placed at the end of a lever 25 having a pivot point 26 and which is situated near the circumference of the blade wheel 21. The other end of the lever is joined to the mobile core of a coil 27 which can be energized and to which the control signals are fed. The brake is held in the non-blocking position by a spring 28 in the absence of control signals. If the blade wheel is mounted in a slipping manner on the spindle 20 a brief energizing of the brake causes a permanent change in position and, consequently, a permanent phase shift. A phase shift brought about in this manner can be cancelled again by energizing the brake again until the change in position of the blade wheel has become equal to the angular distance between two blades. In the embodiment of FIG. 10, the blade wheel is provided with four springs 30 which each extend between a spoke 31 of the blade wheel and a projection 32 of the spindle 20. In this case the brake has to remain energized as long as the phase change has to be maintained. After termination of the brake energizing, the blade wheel automatically assumes the original position again as a result of the action of the springs 30. A blade wheel with attenuation elements can be manufactured in various manners. A possibility is to construct the blade wheel solidly in a suitable plastic in which the blades forming the attenuation elements are embedded. An important advantage of using rotating attenuation elements is that a high frequency can be chosen for exposing or covering the slit S, with a corresponding high fixed modulation frequency of the X-ray beam, which ensures a better uniformity of the exposure of the X-ray detector. The position of the blade wheels can also be controlled in a manner other than that shown in FIG. 9. FIG. 10 shows, by way of example, an eddy-current brake 35 interacting with a blade wheel. In the foregoing it has already been indicated that the fixed modulation of the X-ray beam delivered by the X-ray source can be brought about by cyclically varying the high voltage of the X-ray tube. This produces a varying hardness of the X-ray beam. It is also possible tomodulate the current flowing through the X-ray tube, as a result of which a varying intensity of the X-ray beam is obtained. As an alternative, the fixed modulation can be brought about by means of mechanical means. Such mechanical means should comprise one or more elements which cyclically cover the slit of the slit diaphragm. A first embodiment of such mechanical modulation means is shown in FIG. 11. In the embodiment of FIG. 11, a plate-type element 40 is placed between the X-ray source, of which only the X-ray focus f is shown, and the slit diaphragm 2. The plate-type element 40 extends over the entire length of the slit 2 and is drawn in the position exposing the slit completely. A position of the element 40 covering the slit is drawn by means of broken lines. The plate-type element can swing or rotate with respect to one longitudinal edge 41 thereof. It is possible to cause the plate-type element to swing backwards and forwards cyclically between the two positions drawn, but it is equally possible to cause the plate-type element to rotate about the edge 41 or a spindle joined thereto which extends transversely to the plane of the drawing. In the first case, the plate-type element may advantageously be manufactured from piezoelectric material, the element swinging backwards and forwards between the two positions drawn with respect to the solidly mounted edge under the influence of a cyclic control voltage. In the second case several plate-type blades extending radially with respect to a rotation spindle may be used so that a similar construction arises to that of the blade wheel described earlier, provided the blades extend over the entire length of the slit and thus influence all the sectors simultaneously and in the same manner. Such a construction could be described as a blade roller. It is also possible to use a plate-type element which slides up and down in front of the slit S, as shown at 42 in FIG. 12. Attention is drawn to the fact that the manner of fixed modulation of the X-ray beam 4 is independent of the chosen embodiment of the attenuation elements operating in each sector. In FIG. 11, the attenuation elements are shown by way of example as blade wheels, while in FIG. 12 the attenuation elements are tongue-shaped. Attention is moreover drawn to the fact that the mechanical modulation means may optionally be situated in front of or behind the slit. This also applies to the attenuation elements, so that the mechanical modulation means and the attenuation elements may be interchanged in position with respect to the embodiment shown in FIGS. 11 and 12, or they may be situated on the same side of the slit. This also applies to the embodiments still to be described below. FIGS. 13 and 14 illustrate an alternative embodiment of mechanical modulation means which can be used in a system according to the invention. FIG. 13 shows a segment wheel 45 constructed from a central hub 46, which can rotate around a spindle 47 as indicated by an arrow 48. The hub is provided with a number of radial arms 49 made of material which attenuates X-ray radiation. In the example shown, four arms 49 are used, but it is also possible to use more or fewer arms. In principle one arm can suffice.. The segment wheel is set up in a manner such that in operation, the arms rotate along the slit S. For this purpose, as shown in FIG. 14, the spindle 47 extends transversely to the plane of the slit diaphragm 2. FIG. 14 shows a device according to the invention provided with such a segment wheel in plan view. The space between the arms which attenuate X-ray radiation may be filled in with material transparent to X-ray radiation in order to give the segment wheel more rigidity, but it may also be open. In order to make the effect of the arms rotating along the slit S the same over the entire length of the slit, the arms may advantageously be constructed in segment form, as indicated by broken lines in FIG. 13. A segment wheel as described above may also be constructed with consecutive segments of two materials which both affect the X-ray beam but in different manners. An example is shown in FIG. 15. The segments 50 may, for example, consist of lead and the intervening sectors 51, for example, of copper. Other material combinations may also be used, such as, for example, aluminium and copper or lead and aluminium. It is possible to use a segment wheel in combination with fixed beam modulation obtained by varying the high voltage of the X-ray tube. If the X-ray beam contains both hard and soft radiation, this offers the possibility of filtering out the soft radiation during the peaks of the varying high voltage (FIG. 2) by using a segment wheel, the arms of which situated at said instants in front of the slit blocking the soft X-ray radiation. If a blade roller is used, a similar effect can be achieved by manufacturing the blades alternately of different materials. Attention is drawn to the fact that in FIG. 14 the attenuation elements 7 are indicated as straight tongues which extend parallel to each other. The tongues may, however, also be placed in a fan-type configuration with a convergence point situated in or near the X-ray focus. In addition, the tongues may be constructed in a conically tapering manner in such a fan-type configuration. In addition, several sets of tongues may be used which are placed, for example, behind each other and/or partially above each other. Finally, attention is drawn to the fact that, apart from the preceding modifications, various modifications are obvious to those skilled in the art. Thus, for example, the X-ray diaphragm could itself have a mobile longitudinal edge which is cyclically moved towards the other longitudinal edge or away therefrom in order to modulate the X-ray beam. It is also possible to carry out the common fixed cyclic modulation in accordance with a characteristic other than shown in FIGS. 2 and 4 to 6 incl. FIG. 16 shows, by way of example, a modulation M obtained by half-wave rectification of the sinusoidal high voltage of the X-ray tube, and FIG. 17 shows a variant thereof. FIG. 16 also shows a variant of the manner of control of the beam sector modulators indicated for a single beam sector modulator. According to this variant, the beam sector modulators are controlled at a higher frequency than the common modulation frequency. The amplitude and/or phase of the beam sector modulators can also then be controlled again in the manner already described. If the effect of the specific control signals operating for each sector are left out of consideration, the open and closed phases are equally long in the embodiments shown hitherto. However, this is not necessary. The closed phase could, for example, also be longer than the open phase or vice versa. FIG. 17 illustrates yet another variant of the basic control of the beam sector modulators which may be used, for example, if the beam sector modulators consist of tongue-shaped attenuation elements. According to FIG. 17, the tongues are made to vibrate rapidly and are then brought already vibrating to the open or closed position. As a result of this, the influence of any hysteresis present in the position of the tongue-shaped attenuation elements can be reduced. In addition, in all the situations described, it is possible to use data on the transmission of the body to be investigated already stored in a (computer) memory as a basis. These data may be obtained in earlier investigations of the same body. The control signals for the beam sector modulators can then be generated directly on the basis of said data without use having to be made of a detector such as the dosimeter 8. Such modifications are considered to fall within the scope of the invention.
	abstract	A Thorium fuel rod assembly is disclosed that includes first and second support elements and a number of Thorium fuel rods positioned between support elements. Each of the Thorium fuel rod includes an outer fuel element containing a solid Thorium an inner core element containing Beryllium that is positioned within an interior cavity defined by the outer fuel element. In an exemplary disclosure, the inner core element also defines an inner cavity such that a beam of high energy particles may be directed into the inner cavity of the inner core element to impinge upon a Beryllium nucleus within the inner core element to produce a (p, n) reaction resulting in the emission of a neutron, where the emitted neutron may interact with a Thorium nucleus in the outer fuel element to cause the Thorium nucleus to fission.
	description	The present invention relates to a square pipe, a basket and a spent fuel container which stores spent fuel aggregates. A nuclear fuel aggregate, which has been burnt and is no longer used in its terminal point of a nuclear fuel cycle, is referred to as a spent fuel aggregate. The spent fuel aggregate, which contains high radioactive substances such as FP, needs to be thermally cooled off so that it is cooled off for a predetermined period (for three to six months) in a cooling pit in a nuclear power plant. Thereafter, this is housed in a cask that is a shielding container, and transported by a truck or a ship to a recycling facility where it is stored. Upon housing the spent fuel aggregates in the cask, a holding frame having a lattice shape in its cross-section, called a basket, is used. The spent fuel aggregates are inserted into cells that are a plurality of housing spaces formed in the basket, one by one, thus, it is possible to ensure an appropriate holding strength against vibration, etc. during the transportation. With respect to conventional examples of such a cask, various types thereof have been proposed in “Atomic eye” (issued on Apr. 1, 1998, Nikkan Kogyo Publishing Production) and Japanese Patent Application Laid-Open No. 62-242725. The following description will discuss a cask that forms a premise upon developing the present invention. However, the cask is shown for convenience of explanation, and is not necessarily related to the conventionally known and used device. FIG. 23 is a perspective view that shows one example of a cask. FIG. 24 is a cross-sectional view in the radial direction of the cask shown in FIG. 23. A cask 500 is constituted by a cylinder-shaped trunk main body 501, a resin portion 502 placed on the outer circumference of the trunk main body 501, an outer cylinder 503, a bottom 504 and a lid section 505. The trunk main body 501 and the bottom 504 are forged products of carbon steel that is a γ ray-shielding substance. Moreover, the lid section 505 is constituted by a primary lid 506 and a secondary lid 507 made of stainless steel. The trunk main body 501 and the bottom 504 are joined to each other through butt welding. The primary lid 506 and the secondary lid 507 are secured to the trunk main body 501 with stainless bolts. A hollow O-ring made of metal to which an aluminum coating, etc. is applied is interpolated between the lid section 505 and the trunk main body 501 so as to maintain the inside thereof in an air-tight state. Trunnions 513 which suspends the cask 500 are placed on both of the sides of a cask main body 512 (one of them is not shown). Moreover, buffer members 514 in which timber, etc. is sealed as a buffer member are attached to both of the ends of the cask main body 512 (one of them is not shown). A plurality of inner fins 508 which allows heat conduction are placed between the trunk main body 501 and the outer cylinder 503. The inner fins 508 are made of copper as their material in order to increase the efficiency of heat conductivity. Resin 502 is injected into a space formed by the inner fins 508 in a fluid state, and solidified and formed through a thermo-curing reaction, etc. A basket 509 has a construction formed by collecting 69 square pipes 510 into a bundle as shown in FIG. 23, and is inserted into a cavity 511 of the trunk main body 501 in a fixed state. The square pipe 510 is made of an aluminum alloy in which neutron-absorbing member (boron, B) is mixed so as to prevent the inserted spent fuel aggregate from reaching the criticality. Moreover, each housing space formed by each square pipe 510 is referred to as a cell 515, and each cell 515 can house one spent fuel aggregate. Trunnions 513 which suspends the cask 500 are placed on both of the sides of the cask main body 512 (one of them is not shown). Moreover, buffer members 514 in which timber, etc. is sealed as a buffer member are attached to both of the ends of the cask main body 512 (one of them is not shown). A basket that has been used for a conventional radioactive substance storing container such as a cask and a canister is constituted by combining side faces of a plurality of square pipes with each other, therefore, in order to ensure a sufficient strength at the time of falling down, it is necessary to increase the plate thickness of the square pipe. For example, when a cask horizontally falls down, the load of the spent fuel aggregate is concentrated on the face end portions of each square pipe, thus, it is necessary to provide a thickness that can withstand this impact force. Moreover, since the basket needs to have a function to prevent the inserted spent fuel aggregate from reaching the criticality, the square pipe used for the basket is made of an aluminum alloy in which boron (B) is mixed as a neutron absorbing material. In order to provide this criticality preventive function, the square pipe for the basket needs to have a certain degree of thickness. For this reason, the outer shape dimension of the entire basket tends to become large, resulting in a greater mass in the entire basket. Moreover, in order to protect the cask main body from an accident such as falling down during transportation of the cask, the buffer members 514 (one of which is omitted from the Figure) are attached to both of the ends of the cask (see FIG. 23). The impact at the time of falling of the cask is buffered with the buffer members 514 being crushed. In this case, the margin of crushing in the radial direction, which is used for buffering the impact at the time of horizontal falling down, is ensured by increasing the diameter of the buffer members 514, however, when land transportation is taken into consideration, the diameter of the buffer member 514 can not be increased unduly. When the outer diameter of the cask main body is reduced, the resulting space can be used as the margin of crushing in the buffer member 514, thereby making it possible to reduce the outer diameter of the buffer member 514. It is an object of this invention to achieve at least one of the following points, to provide a basket which is constituted by pipes having a thickness thinner than conventional pipes and consequently to reduce the diameter of the spent nuclear fuel storing container, to provide a basket and square pipes used for storing spent fuel that are easily assembled with reduced offsets of the square pipes constituting the basket, and to provide square pipes used for storing spent fuel and a basket which can alleviate a stress concentration on a specific portion of the square pipe so as to reduce degradation in performances. The spent fuel housing square pipe according to one aspect of the present invention comprises a plurality of square pipes assembled in a staggered arrangement. A spent fuel aggregate is housed inside the square pipes and in a space defined by walls of the square pipes. The corners of walls of each square pipe is formed into a terrace shape having a plurality of steps. When assembling the square pipes the steps of the terrace shape of adjacent square pipes are butted against each other. These square pipes constitute a basket with a plurality of them being combined with each other in a staggered arrangement, therefore, in comparison with a basket constituted by allowing the side faces of square pipes to contact each other, it is possible to make the thickness of the side face of the square pipe thinner. This is because, if the plate thickness of the square pipe side face is equal to the size corresponding to two sheets of the conventional plate, the rigidity would virtually double the conventional rigidity. Therefore, if the plate thickness is equal to the size corresponding to two sheets of the conventional plate, it becomes possible to withstand a greater impact accordingly. Moreover, the corner portion is formed into a terrace shape, and the pipes are combined with each other by getting the step faces butted against each other, therefore, it is possible to prevent offsets in a direction perpendicular to the axis direction. Also, the spent fuel housing square pipe has its corner portion formed into a terrace shape, therefore, strictly speaking, this is not defined as a square pipe. However, since the cross-sectional shape of this pipe perpendicular to the pipe axial direction has a square shape, and the outer shape has virtually a square shape as a whole, in the present invention, this pipe is included in the concept of square pipes. Moreover, the expression “square pipes are combined with each other in the staggered arrangement” means that “square pipes are diagonally combined with each other”, and, for example, this arrangement is shown in FIG. 1. The same is also true of the following description. The square pipes according to the present invention are used not only as a basket in which they are combined in the staggered arrangement so as to be inserted in a radioactive substance storing container such as a cask and a canister but also as a lack in a spent fuel storing pool which stores spent fuel for a predetermined period of time. In this case, the square pipes according to the present invention as they are can be used as a lack, however, it is more preferable to combine the square pipes of the present invention and use in the form of a basket. With this arrangement, after having been stored for a predetermined period of time, a plurality of spent fuel aggregates, stored in the basket, as they are, are replaced into a cask or a canister, and transported and stored so that it is possible to eliminate time-consuming tasks to replace the spent fuel aggregates into a cask, and so on one by one. The same is also true in the other aspects of the present invention. The spent fuel housing square pipe according to another aspect of the present invention comprises a plurality of square pipes assembled in a staggered arrangement. A spent fuel aggregate is housed inside the square pipes and in a space defined by walls of the square pipes. A connecting section which assembles with a connecting section of a square pipe diagonally adjacent thereto, is formed on each of the four corners of the square pipe, and the connecting sections of diagonally adjacent square pipes is are engaged with each other. These spent fuel housing square pipes are connected to each other in a manner so as to be engaged with a connecting section of a square pipe diagonally adjacent thereto, therefore, even when the square pipes are combined with each other, these are less susceptible to disengagement, and the basket can be easily combined. Moreover, if there should be an accidental fall, it is possible to maintain the shape of the basket more firmly. With respect to the engaging construction, in addition to the construction shown in FIG. 11, a construction using dovetail grooves and dovetail joints may be adopted. The spent fuel housing square pipe according to still another aspect of the present invention comprises a plurality of square pipes assembled in a staggered arrangement. A spent fuel aggregate is housed inside the square pipes and in a space defined by walls of the square pipes. Corners of walls of each square pipe is formed into a terrace shape having a plurality of steps and when assembling the square pipes the steps of the terrace shape of adjacent square pipes are butted against each other. A flux trap structure, which fits to the shape of the terrace portion, is formed inside of the square pipe is at least the wall or the terrace portion of the square pipe. In this spent fuel housing square pipe, the flux trap placed in the inside of the square pipe is allowed to have a cross-sectional shape perpendicular to the axis direction that is formed to fit to the cross-sectional shape of the corner portion having a terrace shape perpendicular to the axis direction. Consequently, the flux trap placed inside of the side face can be widened to the vicinity of the corner portion. Moreover, the flux trap placed inside of the side face makes the thickness to the outer wall virtually equal, thereby making it possible to alleviate the influence of stress concentration. At least one of the cross-sectional shapes perpendicular to the axis direction of the flux traps formed on the side face and the terrace portion of the square pipe may be formed to fit to the cross-sectional shape perpendicular to the axis direction of the corner portion having a terrace shape. The basket according to still another aspect of the present invention comprises a square pipe assembly having plurality of square pipes assembled in a staggered arrangement, a spent fuel housing container, such as a cask or a canister, or a spent fuel storing pool, that houses the square pipe assembly. A spent fuel aggregate is housed inside the square pipes and in a space defined by walls of the square pipes. Since this basket is constituted by combining a plurality of square pipes in a staggered arrangement, it is possible to make the thickness of the side face of the square pipe thinner than the basket that is constituted by making the side faces of the square pipes contact with each other. This is because, if the plate thickness of the square pipe side face is equal to the size corresponding to two sheets of the conventional plate, the rigidity would virtually double the conventional rigidity. Therefore, it is possible to make the outer diameter of the basket smaller, and in the case of the same outer diameter, it is possible to increase the number of spent fuel aggregates to be housed. Moreover, when this arrangement is applied to the housing rack in a spent fuel storing pool, etc., it is possible to house the spent fuel aggregates more closely, and also to lighten the system as compared with the boron-stainless product, thus, it becomes possible to reduce the load to be imposed on the structure supporting the rack at the time of any abnormal state. The basket according to still another aspect of the present invention comprises a square pipe assembly having the square pipes disclosed above and assembled in a staggered arrangement so that spaces inside the square pipes and spaces surrounded by the side faces of the square pipes are formed into lattice-shaped cells with used fuel aggregates being housed in the cells, a spent fuel housing container, such as a cask or a canister, or a spent fuel storing pool, that houses the square pipe assembly. A spent fuel aggregate is housed inside the square pipes and in a space defined by walls of the square pipes. This basket is constituted by combining square pipes each having a corner portion formed into, for example, a terrace shape, therefore, in addition to the functions obtained by the above-mentioned basket, offsets in the direction perpendicular to the axis direction can be regulated. Therefore, the basket is more easily combined, and if there should be an accidental fall, it is possible to maintain the shape of the basket more firmly. The basket according to still another aspect of the present invention comprises a square pipe assembly having a plurality of square pipes assembled in a staggered arrangement, wherein corners of walls of each square pipe is formed into a terrace shape having a plurality of steps, and when assembling the square pipes the steps of the terrace shape of adjacent square pipes are butted against each other, a spent fuel housing container, such as a cask or a canister, or a spent fuel storing pool, that houses the square pipe assembly, wherein a spent fuel aggregate is housed inside the square pipes and in a space defined by walls of the square pipes, and a square pipe receiver placed between adjacent square pipes located on the outermost circumference of the square pipe assembly. In this basket, a square pipe receiver is placed between adjacent square pipes located on the outer most circumference of square pipes constituting the basket. This square pipe receiver allows decay heat from the fuel rod aggregates inserted into cells located on the basket outermost circumference to conduct to the cask outer portion efficiently. Moreover, the impact at the time of horizontal falling of the cask is supported by this square pipe receiver, thereby making it possible to prevent collapse of the basket at the time of falling of the cask. The basket according to still another aspect of the present invention comprises a square pipe assembly having a plurality of square pipes assembled in a staggered arrangement, a spent fuel housing container, such as a cask or a canister, or a spent fuel storing pool, that houses the square pipe assembly, wherein a spent fuel aggregate is housed inside the square pipes and in a space defined by walls of the square pipes, and a fastener which fastens the outermost square pipes of the square pipe assembly and a spacer block formed to fit to the inner shape of the spent fuel housing container or the spent fuel storing pool. In this basket, the square pipes and the spacer block are preliminarily secured by the fastening tool, such as bolts, therefore, since no machining process such machining to mount holes is required in the cavity of the canister or cask, no time-consuming tasks are required in the assembling operation. In the spent fuel housing container according to still another aspect of the present invention, there is provided the wherein a basket, which is formed into a lattice shape as a whole by combining a plurality of square pipes with each other in a staggered arrangement, is inserted to a spent fuel housing container main body with its outer shape being fitted to the cavity inner shape of the spent fuel container main body so that a spent fuel aggregate is housed inside each of the cells in the basket. This spent fuel housing container is provided with a basket that is formed into a lattice shape as a whole by combining a plurality of square pipes with each other in a staggered arrangement in its cavity, therefore, in comparison with the basket formed by allowing the side faces of the square pipes to contact each other, this arrangement makes the thickness of the side face of the square pipe thinner. This is because, if the plate thickness of the square pipe side face is equal to the size corresponding to two sheets of the conventional plate, the rigidity would virtually double the conventional rigidity. Therefore, since it is possible to reduce the outer diameter of the basket, it becomes possible to reduce the outer diameter of the spent fuel housing container as compared with the conventional basket. Consequently, it is possible to make the outer diameter of a buffer member to be attached to the spent fuel housing container smaller. Moreover, in the case of the same outer diameter of the spent fuel housing container, it is possible to increase the number of spent fuel aggregates to be housed. Other objects and features of this invention will become apparent from the following description with reference to the accompanying drawings. Embodiments of the present invention will be explained in detail below while referring to the accompanying drawings. However, the present invention is not intended to be limited by the following embodiments. Further, the constituent elements of the following embodiments may include those elements that can be easily arrived at by one skilled in the art. FIG. 1 is a cross-sectional view in the diameter direction that shows one portion of a basket formed by combining square pipes according to a first embodiment of the present invention. In this Figure, an explanation will be especially given of a portion indicated by slanted lines. These square pipes constitute a basket used for housing spent fuel aggregates of a BWR (Boiling Water Reactor). As shown in FIG. 1, this square pipe 300 features that its corner portion (an area indicated by A in the Figure) is molded into a terrace shape. Further, when a basket 200 is constituted by these square pipes 300, the square pipes 300 are assembled with each other in a staggered arrangement with the terrace portions placed on the corner portions being combined with each other. Thus, the insides of the square pipes 300 and spaces surrounded by side faces 12 of the square pipes 300 in the four directions are allowed to form cells 400 and 401 which house fuel rod aggregates. FIG. 25 is a cross-sectional view in the diameter direction that shows one portion of a basket 201 formed by assembling conventional square pipes. As shown in FIG. 25, conventionally, a plurality of square pipes 301 are used and combined with each other to constitute a basket 201 so that the border between cells 402 has a structure in which two sheets of plates are superposed on each other. In the basket 200 according to the first embodiment, a plurality of square pipes 300 are combined with each other in a staggered arrangement so that the border between a cell 400 and a cell 401 is formed by one sheet of plate. For this reason, if this border has a thickness that corresponds to two sheets of the conventional plate, the rigidity would become greater than the conventional rigidity, therefore, in the case of the same rigidity as the conventional one, it is possible to reduce the plate thickness of the square pipe 300 accordingly. Therefore, when the basket 200 is constituted by the square pipes 300 disclosed in the first embodiment, it is possible to reduce the outer diameter of the entire basket in comparison with the conventional construction in which square pipes 301 are arranged with the side faces being made in contact with each other, and it is possible to reduce the outer diameter of the cask correspondingly. Consequently, since the gross weight of the cask is made lighter than the conventional cask, it is possible to reduce the buffering capability required for the buffer member in comparison with the conventional buffer member. Moreover, the outer diameter thus reduced makes it possible to increase the margin of crushing in the radial direction of the buffering member correspondingly, and consequently to reduce the outer diameter of the buffering member. In the case of the same outer diameter in the cask, it is possible to increase the number of spent fuel aggregates to be housed. Moreover, when this arrangement is applied to the housing rack in a spent fuel storing pool, etc., it is possible to house the spent fuel aggregates more closely, and also to lighten the system as compared with the boron-stainless product, thus, it becomes possible to reduce the load to be imposed on the structure supporting the rack at the time of any abnormal state. FIG. 2A and FIG. 2B are explanatory drawings showing how the stress is transmitted to the corner portion of each square pipe 300 in the first embodiment. As shown in FIG. 2A, when the radius R of an corner portion 13 of the corner portion of the square pipe 300 formed into a terrace shape is great, the face which receives a load F becomes small, resulting in a greater possibility of an excessive facial load. Moreover, the great radius R fails to ensure a sufficient thermal conductive area. Consequently, the square pipe 300 is susceptible to damages and other degradation in performances. Even in the case of a load diagonally applied thereon, this might cause degradation in performances in the square pipe 300 due to the stress concentration. In order to avoid the above-mentioned problems, the corner portion 13 in the corner portion of the square pipe 300 formed into a terrace shape is preferably molded so as to have a sharp edge as shown in FIG. 2B. This arrangement gets the adjacent pipes butted against each other on virtually the entire portions of the step faces, therefore, it is possible to reduce the above-mentioned facial load, and also to obtain a sufficient heat conductive area. These functions make it possible to reduce degradation in the performances of the square pipe 300. An explanation will be given of the results of falling tests. First, since the dimension of the square pipe 300 was determined based upon the dimension of the spent fuel aggregates to be housed, evaluation was made based upon the radius R with respect to the plate thickness t of the square pipe 300. Table 1 shows the results of evaluation. TABLE 1Radius REvaluation on stress concentration1.5tbad1.0tbad0.8tbad0.6tgood0.4tbetter0.2tbest0.1tbest0.05t best As a result, when the radius R=0.8 t to 1.5 t, an unwanted stress concentration was exerted on a specific portion (an area indicated by B in FIG. 2A and FIG. 2B) of the square pipe 300. In the case of the radius. R=0.6 t, although the degree of the stress concentration was alleviated, it was still in an undesirable state. Next, in the case of the radius R=0.4 t, the stress concentration was alleviated in a certain degree, and maintained in a comparatively permissible range. In the case of the radius R=0.05 t to 0.2 t, the stress concentration was alleviated considerably to form a desirable state. In particular, in the case of R=0.1 t and 0.05 t, desirable results were obtained and the stress concentration was minimized to such a degree that no problem was raised. Moreover, the sharp edge formed on the corner portion 13 of the square pipe 300 may have a chamfered shape. FIG. 3 is a cross-sectional view in the diameter direction that shows a modified example of the square pipe 300 according to the first embodiment of the present invention. The dimension of this chamfered portion C is preferably set to not more than 1.0 mm (dimension C=not more than 0.2 t) in the same manner as described above. Even in this case, when a load is applied to the basket in the direction of arrow F in the Figure, this arrangement gets the adjacent square pipes 300 butted against each other on virtually the entire portions of the step faces, therefore, it is possible to reduce the stress concentration on a specific portion of the square pipe 300. Moreover, since this arrangement also ensures a sufficient heat conductive area, it becomes possible to reduce degradation in the performances of the basket. Since it is necessary for the basket to have a function to prevent the inserted spent fuel aggregate from reaching the criticality, the square pipe is made of an aluminum alloy to which boron (B) is mixed as a neutron-absorbing material. Natural boron includes B10 that devotes to absorb neutron and B11 that does not devote to absorb neutron. Therefore, when enriched boron B10 having neutron-absorbing capability is used, it is possible to increase the neutron-absorbing capability to a degree corresponding to increased boron B10, in comparison with the case in which natural boron, as it is, is used, supposing that the amount of addition of boron is the same. Therefore, the application of the enriched boron makes it possible to use a square pipe having a thinner plate thickness in comparison with the case in which natural boron, as it is, is used, supposing that the neutron-absorbing capability is the same. From this point of view, in an attempt to make the thickness of the square pipe of the first embodiment thinner than the size corresponding to two sheets of the plates of the conventional square pipe, it is preferable to use an aluminum material to which enriched boron is added. The same is true for the following embodiments. FIG. 4A to FIG. 4C are cross-sectional views in the diameter direction that shows a first modified example of a pipe according to the first embodiment of the present invention. In the above-mentioned square pipe, the corner portion (an area indicated by A in the FIG. 4A) has been molded into a terrace shape with one step, however, this pipe 302 features that the number of steps of the terrace shape is increased so that the corner portion of the pipe 302 is molded into a terrace shape with multiple steps. As shown in FIG. 4B, in the square pipe molded into a terrace shape with one step, the plate thickness of a portion on which a stress is concentrated (portion indicated by D in FIG. 4B) is reduced to one-half the thickness of the side face plate of the square pipe 300. However, as shown in FIG. 4C, in the case of a terrace shape with multiple steps, the plate thickness of a portion on which a stress is concentrated (portion indicated by D in FIG. 4C) is maintained to not less than one-half the thickness of the side face plate of the square pipe 302. For this reason, in comparison with the square pipe 300 having the corner portion molded into a terrace shape with one step, this construction makes it possible to provide higher rigidity and also to reduce the influence of stress concentration. Moreover, these square pipes are molded through a hot-cast extrusion method, and a molding process for a terrace shape with multiple steps makes the thickness of the entire square pipe more uniform, and provides an easier molding process. FIG. 5 is a cross-sectional view in the diameter direction that shows a second modified example of a pipe according to the first embodiment of the present invention. In the above-mentioned square pipe, the corner portion has been molded into a terrace shape, however, these pipes 303 feature that they are connected to each other by using a dovetail groove 700 and a dovetail joint 720 formed on the corner portions (areas indicated by A in the Figure) of the respective square pipes. Upon constructing a basket 203, the dovetail joint 720 formed on one of the pipes 303 is fitted to the dovetail groove 700 formed in the other square pipe 303 so that the square pipes 303 are combined with each other. In this manner, since the square pipes 303 are coupled to each other through the dovetail groove 700 and the dovetail joint 720 so that it is possible to prevent the joined square pipes 303 from coming off, and also to eliminate a positional offset between the square pipes 303. For this reason, the square pipes 303 according to this modified example can be easily assembled to the basket 203, and these are assembled into a cavity with the cask being placed longitudinally to form the basket 203. The square pipe 303 according to the second modified example is made for use in BWRs, however, for example, as shown in FIG. 12, a space which separates the outer wall and the inner wall may be placed inside the side portion of the pipe so as to form a flux strap, so as to store spent fuel aggregates for use in PWRs, which will be explained below. FIG. 6 is a cross-sectional view in the diameter direction that shows one portion of a basket formed by combining square pipes according to a second embodiment of the present invention. As shown in FIG. 6, this square pipe 304 has a virtually square shape in its inner cross-sectional shape in the diameter direction with each corner portion (an area indicated by A in the Figure) molded into a terrace shape. These square pipes 304 constitute a basket which houses spent fuel aggregates for use in PWRs (Pressurized Water Reactors). In PWRs, since the combustion degree of the nuclear fuel becomes higher, the amount of discharge of neutrons is greater in comparison with the spent nuclear fuel of BWRs. Therefore, as shown in FIG. 6, a space is formed inside the side face of the pipe to form a flux trap 170 so that when spent fuel aggregates are housed in the pool, the flux trap 170 is filled with water to speed-reduce neutrons passing through it to the adjacent cell (in the direction of arrow J in the Figure). Thus, these are more easily absorbed by boron contained in the square pipe 304 as a neutron-absorbing material. When a basket 204 is constructed by these square pipes 304, the square pipes 304 are combined in the staggered arrangement as shown in FIG. 6 so that the terrace portions placed on the corner portions are combined with each other. Thus, the insides of the square pipes 304 and spaces surrounded by side faces 12 of the square pipes 304 in the four directions are allowed to form cells 400 and 401 which house fuel rod aggregates. Since the flux trap 170 is formed inside the side face 12, this square pipe 304 has a thicker plate thickness in the side face 12 in comparison with the square pipe according to the first embodiment. Therefore, the corner portions of the square pipes 304 are mutually combined with each other by using a wider area so that this arrangement is less susceptible to an offset, and more easily assembled. Moreover, since the heat conductive areas of the butt faces 180 are made wider so that heat generated from the spent fuel aggregates is more easily transmitted to the trunk main body of the cask more efficiently. Furthermore, when this arrangement is applied to the housing rack in a spent fuel storing pool, etc., it is possible to house the spent fuel aggregates more closely, and also to lighten the system as compared with the boron-stainless product, thus, it becomes possible to reduce the load to be imposed on the structure supporting the rack at the time of any abnormal state. FIG. 7 is a cross-sectional view in the diameter direction that shows a first modified example of a pipe according to the second embodiment of the present invention. In the above-mentioned square pipe, the corner portion has been molded into a terrace shape with one step, however, this pipe features that the number of steps of the terrace shape is increased so that the corner portion of the pipe 305 (an area indicated by A in the Figure) is molded into a terrace shape with multiple steps. As described earlier, in the square pipe molded into a terrace shape with one step, the plate thickness of the corner portion on which a stress is concentrated is reduced to one-half the thickness of the side face plate of the square pipe (see FIG. 4B). However, in the case of the corner portion having a terrace shape with multiple steps, the plate thickness of the corner portion is maintained to not less than one-half the thickness of the side face plate of the square pipe (see FIG. 4C) For this reason, in comparison with the square pipe having the corner portion molded into a terrace shape with one step, this construction makes it possible to reduce the influence of stress concentration. FIG. 8 is a cross-sectional view in the diameter direction that shows a second modified example of a square pipe according to the second embodiment of the present invention. The square pipe according to this modified example, which is the above-mentioned pipe having a terrace shape in the corner portion (an area indicated by A in the Figure), is provided with a protrusion 721 on one of the butt faces 180 and a groove 701 to which the protrusion 721 is fitted on the other face so as to provide an engaging section. These square pipes 306 are combined with each other to form a basket 206 so that it is less susceptible to an offset since the protrusion 721 is fitted to the groove 701. Therefore, the basket 206 is more easily combined and, if there should be an accidental fall, it is possible to maintain the shape of the basket 206 more firmly. Additionally, grooves may be formed in both of the butt faces 180 of the square pipes 306 to be combined with each other, and, for example, a rod shaped member may be inserted into the space formed by these grooves to form an engaging section, thereby preventing an offset in a direction perpendicular to the axis direction. FIG. 9 is a cross-sectional view in the diameter direction that shows a third modified example of a square pipe according to the second embodiment. The square pipe 307 according to this modified example, which is the above-mentioned square pipe having a terrace shape in the corner portion (an area indicated by A in the Figure), is provided with a flux strap 171 also in the corner portion. For this reason, not only the amount of neutrons perpendicularly passing through the side face of the square pipe 307, but also the amount of neutrons diagonally passing through the corner portion of the square pipe 307, can be reduced to a low level. Moreover, since the addition of this flux trap 171 makes it possible to reduce the mass of the square pipe 307, it is possible to reduce the mass of the entire cask, and the size of the buffer member can be reduced correspondingly. FIG. 10 is a cross-sectional view in the diameter direction that shows a fourth modified example of a square pipe according to the second embodiment. According to this modified example, there is provided the square pipe 308, which is the above-mentioned square pipe having the flux strap 171 also in the corner portion (an area indicated by A in the Figure), wherein the cross-sectional shape perpendicular to the axis direction of the flux trap 172 formed inside the side face 12 is made coincident with the shape of the terrace portion formed in the corner portion. The state “being made coincident with the shape of the terrace portion” includes not only being made coincident with the terrace portion but also being made coincident diagonally with the shape, as shown in FIG. 10. In addition to the effects obtained through the third modified examples, this arrangement makes it possible to expand the flux trap 172 formed inside the side face to the vicinity of the corner portion, thus, it is possible to widen the area to speed-reduce neutrons. Moreover, it becomes possible to ensure a sufficient thickness in the vicinity of the corner portion and consequently to ensure a sufficient rigidity, so as to reduce the stress concentration. FIG. 11 is a cross-sectional view in the diameter direction that shows a fifth modified example of a square pipe according to the second embodiment. According to this modified example, there is provided the square pipe 309 wherein, with respect to the connecting sections formed on the four corner portions of the square pipe (areas indicated by A in the Figure), at least two adjacent connecting sections have directions in which they are engaged with the respective connecting sections of square pipes 309 diagonally adjacent thereto, and the directions are different from each other by virtually 90 degrees. In this arrangement, the corner portions are respectively provided with a protrusion 722 and a groove 702 to which the protrusion is fitted so as to have an engaging structure. Square pipes 309 are coupled to each other through these protrusion 722 and groove 702 so that the square pipes 309 are less susceptible to coming off when combined with each other, and easily combined to form a basket 209. Moreover, these square pipes 309 are less susceptible to rattling, and, if there should be an accidental fall, it is possible to maintain the shape of the basket 209 more firmly. Moreover, since it is possible to widen the heat conductive area, decay heat generated from the spent fuel aggregates can be transmitted efficiently. A flux trap may be placed in the corner portion also in the present modified example. Since the square pipe according to this modified example has an engaging structure in each of the corner portions, this is suitably applied to the case in which a basket for use in PWRs, which has a greater apparent side-face plate thickness, is constructed, or this may be also applied to a basket for use in BWRs. In this case, it is preferable to make the thickness of the side face thicker than that of the square pipe normally used for BWRs. FIG. 12 is a cross-sectional view in the diameter direction that shows a sixth modified example of a square pipe according to the second embodiment. In the above-mentioned square pipe, corner portions (areas indicated by A in the Figure) have connecting sections each having an engaging structure, however, this square pipe 310 is that, with respect to the connecting sections formed on the four corner portions, at least two adjacent connecting sections have directions in which they are engaged with the respective connecting sections of square pipes 310 diagonally adjacent thereto, and the directions are different from each other by virtually 90 degrees. These are combined with each other through a dovetail groove 700 and a dovetail joint 720 formed on the respective corner portions of the square pipes 310. When a basket 210 is constructed, the dovetail joint 720 formed on one of the square pipe 310 is fitted to the dovetail groove 700 formed in the other square pipe 310 so as to combine the square pipes 310 with each other. Square pipes 310 are coupled to each other through these dovetail groove 700 and dovetail joint 720 so that the combined square pipes 310 are less susceptible to coming off from each other and a positional offset between the square pipes 310. The square pipes 310 according to this modified example are easily assembled into a basket 210, and the assembling operation is carried out with the square pipes 310 placed longitudinally so as to construct the basket 210. FIG. 13A and FIG. 13B are cross-sectional views in the diameter direction that shows a structural example of a basket according to the second embodiment. These baskets 211 and 212 feature that the above-mentioned square pipe is divided into a plurality of elements and these elements are combined to form the basket. FIG. 13A shows an example in which a square pipe is formed by combining a divided element 350 having a “ko”-letter shape (Japanese Kana character) in its cross-section and a divided element 351 having a linear shape. Moreover, FIG. 13B shows an example in which a square pipe is formed by combining divided elements 352 and 353, each having an L-letter shape. With this arrangement, it becomes possible to construct a cell having a size greater than the size that is available by an extrusion molding machine, and these cells can be molded through an extrusion molding machine that uses a smaller molding pressure. This basket is suitably applied to a basket for use in PWRs having a greater apparent side-face plate thickness, or this may be also applied to a basket for use in BWRs without a flux trap. Next, the following description will discuss a basket constructed by the above-mentioned pipes 300 together with the entire cask as a third embodiment of the present invention. Not limited by the square pipe 300, the basket can be constructed by using the other square pipes disclosed in the above-mentioned first and second embodiments. FIG. 14 is a perspective view that shows a cask according to a third embodiment of the present invention. FIG. 15 is a cross-sectional view in the axis direction of the cask shown in FIG. 14. FIG. 16 is a cross-sectional view in the diameter direction of the cask shown in FIG. 14. FIG. 16 shows only a ¼ of the entire structure. This cask 100, which virtually has the same structure as the cask 500 shown in FIG. 23, is that the inside of a cavity 102 of the trunk main body 101 is formed into a shape that is coincident with the outer shape of the basket 130. The shape of the inner face of the cavity 102 is formed by fraise machining carried out by using a dedicated machining device, which will be described later. In addition to the fraise machining, this may be formed by shaper machining. Moreover, the machining device, which will be described later, is a so-called lateral machining device in which machining is carried out with the container being placed laterally, however, not limited to this, a longitudinal machining device in which machining is carried out with the container being placed longitudinally may be used. In the cask 100 shown in the same Figure, a trunk main body 101 and a bottom plate 104 are roller forged products made of carbon steel having a γ-ray shielding function. Instead of carbon steel, stainless steel may be used. The trunk main body 101 and the bottom plate 104 are joined to each other by welding, etc. Moreover, in order to ensure a sealing performance as a pressure-resistant container, a metal gasket is interpolated between the lid section 109 and the trunk main body 101. The trunk main body 101 and the bottom plate 104 may be molded as an integral part by using a processing method such as a hot-cast expansion molding method. In this case, since a welding process and a heat treatment process after the welding can be omitted, it is possible to make the manufacturing process easier. A neutron-shielding material 106, such as resin and silicone rubber, that is a high-molecular material with a high hydrogen content, having a neutron-shielding function, is injected between the trunk main body 101 and the outer cylinder 105. Moreover, a plurality of inner fins 107 used for thermal conduction are welded between the trunk main body 101 and the outer cylinder 105 so that the neutron shielding member 106 is injected into gaps formed by the inner fins 107 in a fluid state, and solidified therein through a thermo-setting reaction or the like. With respect to the inner fins 107, a material having a high thermal conductivity such as Cu and Al is preferably used as the inner fins 107, and it is preferable to place them with a higher density in a place having a higher quantity of heat so as to carry out heat radiation uniformly. Moreover, a thermal expansion margin 108 of several millimeters is placed between the neutron shielding member 106 and the outer cylinder 105. This thermal expansion margin 108 is formed as follows, first, a sublimation mold formed by embedding a heater in a hot-melt bonding agent is placed on an inner surface of the outer cylinder 105, and to this is injected the neutron shielding material 106 and solidified therein, and the heater is then heated and the material is melted and discharged (not shown). Moreover, another arrangement may be used in which, a honeycomb material having predetermined strength is placed inside the thermal expansion margin 108 so that the honeycomb material may be compressed as the neutron shielding member is thermally expanded. The lid section 109 is constituted by a primary lid 110 and a secondary lid 111. This primary lid 110 has a disc shape made of a material such as stainless steel and carbon steel which shields y-rays. Moreover, the secondary lid 111 also has a disc shape made of stainless steel, etc., and resin 112 is sealed in the upper face thereof as a neutron shielding member. The primary lid 110 and the secondary lid 111 are attached to the trunk main body 101 by stainless bolts 113. Further, metal gaskets are respectively placed between the primary lid 110 as well as the secondary lid 111 and the trunk main body 101 so as to maintain the sealing property inside thereof. Moreover, an assistant shielding member 115 in which resin 114 is sealed is placed on the periphery of the lid section 109. Trunnions 117 which suspends the cask 100 are placed on both of the sides of the cask main body 116. FIG. 14 shows the structure with the assistant shielding member 115 attached thereto, however, at the time of transportation of the cask 100, the assistant shielding member 115 is detached and a buffering member 118 is attached thereto (see FIG. 15). This buffering member 118 has a structure in which a buffering material 119 such as red wood material is sealed inside the outer cylinder 120 formed by a stainless steel material. Moreover, the shielding function may be enhanced so as to eliminate the necessity of using the assistant shielding member 115. In this case, it is not necessary to attach and detach the assistant shielding member 115 so as to attach and detach the buffering member 118, and consequently to reduce the operation tasks. Although not clearly shown by FIG. 16, the basket 130 is assembled by 21 square pipes 300 that constitute 69 cells 131 which houses spent fuel aggregates. Each of the square pipes 300 is made of an aluminum composite member formed by adding powder of B or B compound having a neutron-absorbing function to Al or Al alloy powder. Moreover, with respect to the neutron-absorbing material, besides boron, cadmium may be used. The number of the square pipes 300 is not limited by this example, and it is properly increased or decreased depending on the design of the basket, cask, etc. FIG. 17 is a flow chart that shows a manufacturing method of the above-mentioned square pipe. First, Al or Al alloy powder is prepared by a quenching solidification method such as an atomizing method (step S401), and power of B or B compound is also prepared (step S402), then, these two particles are mixed with each other by a cross rotary mixer, etc. for 10 to 15 minutes (step S403). With respect to Al or Al alloy, examples thereof include, pure aluminum metal, Al—Cu-based aluminum alloy, Al—Mg-based aluminum alloy, Al—Mg—Si-based aluminum alloy, Al—Zn—Mg-based aluminum alloy and Al—Fe-based aluminum alloy. Moreover, with respect to the above-mentioned B or B compounds, examples thereof include B4C and B2O3. The amount of addition of boron to aluminum is preferably set in the range of not less than 1.5 weight % to not more than 9 weight % based upon the B-amount conversion. More preferably, it is set in the range of not less than 2.0 weight % to not more than 5.0 weight %. The amount of not more than 1.5 weight % fails to provide a sufficient neutron-absorbing function, and the amount exceeding 9 weight % makes it impossible to carry out a molding operation and also causes a reduction in the ductility of the resulting material. In the case of the same amount of addition of boron to aluminum, the application of enriched boron B10 makes it possible to enhance the neutron-absorbing capability in comparison with natural boron. For example, in general, the rate of B10 in natural B4C is approximately 19%, however, when B4C in which B10 is enriched to 98% is used, the same amount of addition of B4C increases the neutron-absorbing capability to approximately 5 times. Therefore, in the case of the application of enriched boron, it is possible to provide the same neutron-absorbing capability by using a thinner plate thickness in comparison with a case in which natural boron is used. Moreover, in the case of the same plate thickness and neutron-absorbing capability, it is possible to reduce the amount of application of boron. Next, the mixed powder is sealed in a rubber case and this is subjected to a powder molding process by uniformly applying a high pressure from all the directions at normal temperature by using CIP (Cold Isostatic Press) (step S404). The molding conditions of CIP are, 200 MPa in molding pressure, 600 mm in the diameter and 1500 mm in length in the molded product. By applying a pressure uniformly from all the directions by using CIP, it is possible to provide a molded product that has a high density and is less susceptible to deviations in the molding density. Successively, the above-mentioned powder molded product is vacuum-sealed into a case, and heated to 300° C. (step S405). This degassing process eliminates gas components and moisture component from the case. In the nest process, the molded product that has been vacuum-degassed is re-molded by HIP (Hot Isostatic Press) (step S406). The molding conditions of HIP are, temperature 400° C. to 450° C., time 30 sec, and pressure 6000 ton, and the diameter of the molded product is set to 400 mm. An outer face grinding process and an end face grinding process are carried out so as to remove the case (step S407), and a hot-case extrusion is carried out on the billet by using a port hall extruder (step S408). In this case, with respect to the extrusion conditions, the heating temperature is set in the range of 500° C. to 520° C. and the extruding speed is set to 5 m/min. The die used in this extruding process is set to have the same cross-sectional shape as the outer shape of a pipe to be molded so that the pipe explained in the above-mentioned embodiment can be molded. Without sealing the molded product in the case by using CIP in step S405, it may be re-molded by HIP after having been vacuum-degassed in the HIP container. This arrangement makes it possible to eliminate the outside grinding process which removes the case, and consequently to reduce the process. Moreover, in place of the HIP process, vacuum sintering and vacuum hot pressing processes may be used. In this case also, since it is possible to eliminate the outside grinding process which removes the case, time-consuming tasks are not required for the manufacturing process. Next, after the extrusion molding process, the resulting product is subjected to a tensile correcting process (step S409), and a non-normal portion and an evaluation portion are cut to form a product (step S410). As shown in FIG. 1, the square pipe 300 thus completed has a square shape having one side of 162 mm and an inner side of 151 mm in its cross-section. Moreover, the corner portion of the square pipe 300 is molded into a sharp edge having a radius R=not more than 1.0 mm through an extruding process. The dimension tolerance is set to 0 with respect to minus tolerance based upon the standard required. Additionally, with respect to the manufacturing method of this square pipe 300, the applicant of the present invention has applied another method for a patent on May 27, 1999 (“basket and cask”), therefore, the manufacturing process may be carried out by reference to this method. The square pipe 300, manufactured through the above-mentioned processes, is successively inserted following the machined shape inside the cavity 102. When there are bending and twisting occurring in the square pipe 300, since the minus tolerance of the dimension is zero, an attempt to insert the square pipe 300 causes a difficulty in insertion due to accumulation of tolerances and influence of bending, and a forceful insertion causes an excessive stress applied on the square pipe 300. For this reason, with respect to all or some square pipes 300 thus manufactured, bending and twisting thereof may be preliminarily measured by a laser measuring device, etc., and an optimal inserting position is found based upon the measured data by using a computer. This arrangement makes it possible to easily insert the square pipe 300 into the cavity 102, and it is also possible to uniformly set the stress imposed on the respective square pipes 300. Moreover, as shown in FIG. 16, among cavities 102, dummy pipes 133 are respectively inserted on both of the sides of the square pipe row having the number of cells of five or seven. The objects of these dummy pipes 133 are, to reduce the weight of the trunk main body 101, to make the thickness of the trunk main body 101 uniform and to firmly secure the square pipe 300. This dummy pipe 133 is also made of aluminum containing boron, and manufactured in the same processes as described above. These dummy pipes 133 may be made of simple aluminum material or may be omitted if there is no necessity of reducing the weight, etc. Next, an explanation will be given of a case in which the machining of the cavity 102 of the trunk main body 101 is carried out by using a lateral machining device. FIG. 18 is a schematic perspective view that shows a machining device of the cavity 102. This machining device 140 is constituted by a fixing table 141 that is allowed to penetrate the inside of the trunk main body 101 and placed and fixed inside the cavity 102, a movable table 142 that is allowed to slide on the fixing table 141, a saddle 143 that is positioned and secured on the movable table 142, a spindle unit 146 constituted by a spindle 144 and a driving motor 145 placed on the saddle 143, and a face mill 147 placed on a spindle axis. Moreover, a repulsive force receiver 148 made by molding the contact portion according to the inner shape of the cavity 102 is placed on the spindle unit 146. This repulsive force receiver 148, which is freely attached and detached, is allowed to slide in the arrow direction in the Figure along a dovetail groove (not shown). Moreover, the repulsive force receiver 148 is provided with a clamping device 149 with respect to the spindle unit 146, and secured to a predetermined position. Moreover, a plurality of clamping devices 150 are attached to the lower groove of the fixing table 141. Each clamping device 150 is constituted by a hydraulic cylinder 151, a shift block 152 having a wedge shape attached to the hydraulic cylinder 151 and a fixing block 153 that is allowed to contact the shift block 152 on its slanted face, and the portion indicated by slanting lines in the Figure is attached to the inner face of the groove in the fixing table 141. When the shaft of the hydraulic cylinder 151 is driven, the shift block 152 is allowed to contact the fixing block 153 so that the shift block 152 is shifted downward slightly by the effect of the wedge (indicated by a dotted line in the Figure). Thus, the lower face of the shift block 152 is pressed onto the inner face of the cavity 102, thereby making it possible to secure the fixing table 141 inside the cavity 102. Moreover, the trunk main body 101 is placed on a rotary supporting base 154 made of a roller such that it is allowed to freely rotate in the diameter direction. The height of a face mill 147 on the fixing table 141 is adjusted by putting a spacer 155 between the spindle unit 146 and the saddle 143. The thickness of the spacer 155 is set to the same as the dimension of one side of the square pipe 300. The saddle 143 is allowed to shift in the diameter direction of the trunk main body 101 by rotating a handle 156 attached to the movable table 142. The movable table 142 is controlled in its shift by a servo-motor 157 and a ball screw 158 that are placed on the end portion of the fixing table 141. As the machining process proceeds, the shape of the inside of the cavity 102 is changed so that it is necessary to change the repulsive force receiver 148 and the shift block 152 of the clamping device 150 to those having appropriate shapes. FIG. 19A to FIG. 14D are schematic explanatory views showing how the cavity is machined. First, a fixing table 141 is secured to a predetermined position inside the cavity 102 by the clamping device 150 and the repulsive force receiver 148. Next, as shown in FIG. 19A, the spindle unit 146 is shifted along the fixing table 141 at a predetermined cutting speed so that a cutting process inside the cavity 102 is carried out by the face mill 147. Upon completion of the cutting process at this position, the clamping device 150 is disengaged to release the fixing table 141. Next, as shown in FIG. 19B, the trunk main body 101 is rotated on the rotary supporting base 154 by 90 degrees so that the fixing table 141 is secured by the clamping device 150. Then, a cutting process is carried out by the face mill 147 in the same manner as described above. Thereafter, the same process as described above is further repeated twice. Next, the spindle unit 146 is rotated by 180 degrees so that, as shown in FIG. 19C, a cutting process inside the cavity 102 is successively carried out. In this case also, in the same manner as described above, the process is repeated while the trunk main body 101 is rotated by 90 degrees. Next, as shown in FIG. 19D, the position of the spindle unit is raised by allowing the spacer 155 to engage the spindle unit 146 as shown in FIG. 19D. Then, at this position, the face mill 147 is transported toward the axis direction so that a cutting process inside the cavity 102 is carried out. This process is repeated while the trunk main body 101 is rotated by 90 degrees so that a shape required for inserting the square pipe 300 is virtually finished. The cutting process for a portion in which the dummy pipe 133 is inserted is carried out in the same manner as shown in FIG. 19D. However, the thickness of the spacer which adjusts the height of the spindle unit 146 is set to the same as one side of the dummy pipe 133. In the above explanation, the cutting process inside the cavity 102 is carried out with the trunk main body 101 being placed laterally, however, by using a longitudinal machining device, the cutting process inside the cavity 102 may be carried out with the trunk main body 101 being placed on the rotary table longitudinally. The spent fuel aggregates to be housed in the cask 100 include fission substances and fission products, etc., and generate radioactive rays and decay heat so that the heat removing function, shielding function and criticality prevention function of the cask 100 need to be positively maintained for a storage period (approximately, 60 years) In the cask 100 according to the first embodiment, the inside of the cavity 102 of the trunk main body 101 is subjected to a machining process so that the basket 130 constituted by the square pipes 300 is inserted therein with the outside of the basket 130 being maintained in a contact state or a nearly contact state (without a space area), therefore, it is possible to widen the heat conductive face between the square pipes 300 and the trunk main body 101. Moreover, the inner fins 107 are placed between the trunk main body 101 and the outer cylinder 105 so that heat released from the fuel rods is allowed to conduct to the trunk main body 101 through the square pipes 300 or helium gas filled therein, and released from the outer cylinder 105 mainly through the inner fins 107. As described above, the heat-removing process of decay heat is carried out efficiently so that, in the case of the same quantity of decay heat, it is possible to keep the temperature inside the cavity 102 lower than the conventional system. Moreover, γ-rays generated by the spent fuel aggregates are shielded by the trunk main body 101, the outer cylinder 105, the lid section 109, etc. made of carbon steel or stainless steel. Furthermore, neutrons are shielded by the neutron-shielding member 106 so that radiation-related workers become less susceptible to the influence of exposure. More specifically, a designing process is carried out to obtain a shielding function such that the surface dose equivalent factor is set to not more than 2 mSv/h with the dose equivalent factor of 1 m from the surface being set to not more than 100 μSv/h. Since the square pipes 300 constituting the cells 131 use an aluminum alloy containing boron, it is possible to absorb neutrons and consequently to prevent the spent fuel aggregates from reaching the criticality. As described above, according to the cask 100 of the third embodiment, since the inside of the cavity 102 of the trunk main body 101 is subjected to a machining process and since the square pipes 300 constituting the periphery of the basket 130 is inserted therein in a contact state, it is possible to improve the heat conductivity in the square pipes 300. Moreover, since the space area inside the cavity 102 is eliminated, it is possible to make the trunk main body 101 more compact and lighter. Even in this case, the number of the square pipes 300 to be housed is not reduced. In contrast, when the outer diameter of the trunk main body 101 is made to be the same as the cask shown in FIG. 23, since cells the number of which is increased correspondingly are prepared, it is possible to increase the number of spent fuel aggregates to be housed. More specifically, in the present cask 100, the number of spent fuel aggregates is increased to 69, and the outer diameter of the cask main body 116 is maintained to, for example, 2560 mm with the weight being reduced to 120 tons. Moreover, since the square pipes 300 are assembled in a staggered arrangement, it is possible to make the thickness of the square pipe 300 thinner in comparison with the conventional structure. Therefore, the outer diameter of the basket can be reduced in comparison with the conventional structure, and the outer shape of the cask can be reduced in comparison with the conventional structure accordingly. Furthermore, when the thickness of the square pipe 300 is made to have a size identical to the two sheets of the conventional pipe, the rigidity becomes higher than the conventional pipe, therefore, it is possible to build the basket 130 more strongly, and consequently to improve the reliability of the cask 100. FIG. 20A and FIG. 20B are cross-sectional views in the circumferential direction that shows an example in which a basket according to the present invention is housed inside the cavity of a cask as a fourth embodiment of the present invention. Since the basket according to the present invention is constructed by combining a plurality of square pipes with each other in a staggered arrangement, there are some portions in which no side faces exist along the outer circumference of the basket. When this basket is inserted into the cavity of a cask with these portions being left as they are, gaps are formed between the inner wall of the cavity and the fuel rod aggregates, resulting in difficulties in releasing decay heat generated from the fuel rod aggregates toward the outside of the cask. Moreover, since there are portions in which no side faces exist, it is not possible to support an impact imposed at the time when the cask falls down horizontally, therefore, the basket might collapse at the time of falling of the cask. In order to solve the above-mentioned problems, a square pipe receiver 30 constituted by side plates is placed in each of the portions where there are no side faces on the outer circumference of the basket 213 as shown in FIG. 20A, and the basket 213 is inserted into the cavity 102. A portion of the square pipe receiver 30 against which the corner portion of the square pipe 300 is butted (an area indicated by A in the Figure) is made coincident with the shape of the corner portion of the square pipe 300. The basket 213 may be inserted into the cavity 102 after the square pipe receiver 30 has been attached to the basket 213, or after the square pipe receiver 30 has been preliminarily attached to the inner wall of the cavity 102 by fastening tools such as bolts, the basket 213 may be inserted into the cavity 102. Moreover, the portion of the square pipe receiver 30 against which the corner portion of the square pipe 300 is butted (the area indicated by A in the Figure) may be fixed through welding to form a basket 213. By using the square pipe receiver 30, decay heat from the fuel rod aggregates inserted into the cells 401 on the periphery of the basket 213 is allowed to conduct to the outer portion of the cask efficiently. Moreover, since this square pipe receiver 30 makes it possible to support an impact imposed at the time of horizontal falling of the cask, it is possible to prevent the basket 213 from collapsing at the time of falling of the cask. As shown in FIG. 20B, the inner wall of the cavity 102 may be molded into a convex shape to form a square pipe receiver 30. With this arrangement, in comparison with the case in which the square pipe receiver 30 is constituted by side plates, it is possible to eliminate the tasks to secure the side plate to the cavity inner wall, etc. FIG. 21 is a cross-sectional view in the circumferential direction that shows an example in which a basket according to the present invention is housed in a canister as a fifth embodiment of the present invention. Since a housing container used for the canister has a thickness thinner than the housing container used for the cask, it is difficult to mold the inner cross-sectional shape in the diameter direction in a manner so as to match the outer shape of the basket. Therefore, when a basket 215 constituted by square pipes 300 is inserted into a canister trunk 900, a spacer block 35 that matches the inner shape of the canister trunk 900 is attached onto the outer circumference of the basket 215 as shown in the Figure so that the outer shape of the basket 215 is allowed to match the inner shape of the cross-section in the radial direction of the canister trunk 900. In the case of casks, this method is efficiently applied to such a cask in which the inner face machining is minimized. The spacer block 35 is secured to the square pipe 300 and the square pipe receiver 30 explained in a fourth embodiment by bolts 36 that are fastening members. Instead of bolts, rivets may be used as the fastening members. After the spacer block 35 has been attached to the entire periphery of the basket 215, the basket 215 is inserted into the canister trunk 900. With this arrangement, the basket according to the present invention can be applied to a canister, and since no mounting holes, etc. are required inside the cavity of the canister, no time-consuming tasks are required for the assembling operation. As explained in the fourth embodiment, a convex portion may be formed on the side of the spacer block 35 contacting the square pipe 300 as a square pipe receiver 30. Moreover, the spacer block 35 and the square pipe 300 are joined to each other through fastening members, however, instead of the fastening members, these devices may be joined to each other through welding, brazing or bonding. FIG. 22A to FIG. 22C are cross-sectional views in the diameter direction that shows an example of a basket according to the present invention. As shown in this Figure, the basket according to the present invention includes, for example, a structure in which the butt face 181 of each square pipe is formed by a curve and these square pipes are combined with each other in a staggered arrangement (FIG. 22A), another structure in which a protrusion 721 and a groove 701 are formed on each butt face 182 so that the protrusion is fitted to the groove (FIG. 22B) and the other structure in which a groove 701 is formed in the butt face 182 so that a rod 725 or the like is inserted to this groove so as to prevent an offset (FIG. 22C). In the example shown in FIG. 22A, since the butt face 181 is formed by a curve, no great stress concentration is exerted on the butt face 181 even when a load F is imposed in the arrow direction. In the examples shown in FIG. 22B and FIG. 22C, the protrusion 721 and the groove 701 or the rod 725 and the groove 701 are allowed to engage each other so that it is possible to prevent an offset in the direction perpendicular to the axis direction. These are merely examples, and the combination of the square pipes is not intended to be limited by these, therefore, any combination that can be easily arrived at by one skilled in the art is included therein. As described above, according to the spent fuel housing square pipe according to one aspect of the present invention, in comparison with a basket constituted by allowing the side faces of square pipes to contact each other, it is possible to provide a higher rigidity, and consequently to make the thickness of the side face of the square pipe thinner. Thus, it becomes possible to reduce the outer diameter dimension of the basket. Moreover, the corner portion is formed into a terrace shape, and the pipes are combined with each other by getting the step faces butted against each other, therefore, it is possible to prevent offsets in a direction perpendicular to the axis direction, and consequently to easily assemble the basket. Moreover, it is possible to set the thickness of the corner portion to not less than one-half the thickness in the side face of the square pipe. Therefore, in comparison with the pipe molded to have a terrace shape with one step, it is possible to make the influence of stress concentration smaller. Furthermore, movements in the direction perpendicular to the axis direction are regulated by the engaging portion formed on the step face so that the square pipes become less susceptible to offsets when they are combined with each other. Therefore, the basket is more easily combined and, if there should be an accidental fall, it is possible to maintain the shape of the basket more firmly. According to the spent fuel housing square pipe of another aspect of the present invention even when the square pipes are combined with each other, these are less susceptible to disengagement, and the basket can be easily combined. Moreover, these square pipes are less susceptible to rattling, and, if there should be an accidental fall, it is possible to maintain the shape of the basket more firmly. Moreover, no offset occurs even when there is a movement in a specific direction, and offsets in the square pipes are regulated with respect to movements in any direction. For this reason, the basket can be easily combined, and if there should be an accidental fall, it is possible to maintain the shape of the basket more firmly. Furthermore, the flux trap makes it possible to the apparent thickness of the square pipe so that these square pipes can be combined with each other with wider areas on the corner portion of the respective pipes. Therefore, these square pipes are less susceptible to offsets, and can be easily combined. Moreover, it is possible to widen the heat conducting area of the joining section, and consequently to properly conduct heat generated from the spent fuel aggregates to the trunk main body of the cask. Furthermore, it is possible to exert a function which speed-reduces and absorbs neutrons that pass through the cells housing spent fuel aggregates in a diagonal direction, in addition to the functions exerted by the above-mentioned square pipes. Moreover, this construction also makes the square pipe further lighter so that it is possible to reduce impact energy at the time of falling down. According to the spent fuel housing square pipe of still another aspect of the present invention, the flux trap placed inside of the side face can be widened to the vicinity of the corner portion. Moreover, the flux trap placed inside of the side face makes the thickness to the outer wall virtually equal, thereby making it possible to prevent any weak portion being locally formed and consequently to alleviate the influence of stress concentration. Therefore, it becomes possible to properly maintain the performances of the square pipe and consequently to reduce degradation in the performances of the basket. Moreover, it is possible to ensure the thickness in the vicinity of the corner portion of the square pipe and consequently to maintain a sufficient rigidity, therefore, it becomes possible to alleviate the stress concentration in the vicinity of the corner portion of the square pipe. Thus, it becomes possible to properly maintain the performances of the square pipe and consequently to reduce degradation in the performances of the basket. Furthermore, it is possible to alleviate the stress concentration on the butt face, and consequently to reduce degradation in the performances of the basket. Moreover, a proper contact area is ensured on the butt face in the corner portion of the square pipe, it is possible to alleviate the stress concentration on the butt face. Therefore, it is possible to reduce degradation in the performances of the basket, and consequently to enhance the reliability of the basket. Furthermore, it is possible to increase the gross amount of B10 that is used as a neutron absorbing member. Therefore, by using the enriched boron, in comparison with the case without using this, it is possible to obtain the same neutron absorbing ability with a thinner plate thickness, therefore, this arrangement is beneficial in reducing the weight of the basket and in minimizing the dimension of the outer diameter thereof. According to the basket of still another aspect of the present invention, since it is possible to make the rigidity of each pipe higher in comparison with the conventional basket that is constituted by making the side faces of the square pipes contact with each other, it is possible to make the thickness of the side face of the square pipe thinner in a corresponding manner. The thickness of the side face of the square pipe is made thinner. Consequently, it is possible to make the outer diameter of the basket smaller, and in the case of the same outer diameter, it is possible to increase the number of spent fuel aggregates to be housed. Moreover, when this arrangement is applied to the housing rack in a spent fuel storing pool, etc., it is possible to house the spent fuel aggregates more closely, and also to make the system lighter as compared with the boron-stainless product, thus, it becomes possible to reduce the load to be imposed on the structure supporting the rack at the time of any abnormal state. According to the basket of still another aspect of the present invention, offsets in the direction perpendicular to the axis direction can be regulated. Therefore, the basket is more easily combined, and if there should be an accidental fall, it is possible to maintain the shape of the basket more firmly. According to the basket of still another aspect of the present invention, the square pipe receiver allows decay heat from the fuel rod aggregates inserted into cells located on the basket outermost circumference to conduct to the cask outer portion efficiently. Moreover, since the impact at the time of horizontal falling of the cask is supported by this square pipe receiver, it is possible to prevent collapse of the basket at the time of falling of the cask, and consequently to maintain the stability of the basket. According to the basket of still another aspect of the present invention, since the fastener such as a bolt(s) is used, no machining process such machining which mounts holes is required in the cavity of the canister or cask, no time-consuming tasks are required in the assembling operation. According to the spent fuel housing container of still another aspect of the present invention, in comparison with the basket formed by allowing the side faces of the square pipes to contact each other, it is possible to provide a higher rigidity, and consequently to make the thickness of the side face of the square pipe thinner. Since it is possible to reduce the outer diameter of the basket, it becomes possible to reduce the outer diameter of the spent fuel housing container as compared with the conventional basket. Consequently, it is possible to make the outer diameter of a buffer member to be attached to the spent fuel housing container smaller. Moreover, in the case of the same outer diameter of the spent fuel housing container, it is possible to increase the number of spent fuel aggregates to be housed. Although the invention has been described with respect to a specific embodiment for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art which fairly fall within the basic teaching herein set forth.

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